Sample records for carrying null mutations
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TBX6 Null Variants and a Common Hypomorphic Allele in Congenital Scoliosis
Wu, N.; Ming, X.; Xiao, J.; Wu, Z.; Chen, X.; Shinawi, M.; Shen, Y.; Yu, G.; Liu, J.; Xie, H.; Gucev, Z.S.; Liu, S.; Yang, N.; Al-Kateb, H.; Chen, J.; Zhang, Jian; Hauser, N.; Zhang, T.; Tasic, V.; Liu, P.; Su, X.; Pan, X.; Liu, C.; Wang, L.; Shen, Joseph; Shen, Jianxiong; Chen, Y.; Zhang, T.; Zhang, Jianguo; Choy, K.W.; Wang, Jun; Wang, Q.; Li, S.; Zhou, W.; Guo, J.; Wang, Y.; Zhang, C.; Zhao, H.; An, Y.; Zhao, Y.; Wang, Jiucun; Liu, Z.; Zuo, Y.; Tian, Y.; Weng, X.; Sutton, V.R.; Wang, H.; Ming, Y.; Kulkarni, S.; Zhong, T.P.; Giampietro, P.F.; Dunwoodie, S.L.; Cheung, S.W.; Zhang, X.; Jin, L.; Lupski, J.R.; Qiu, G.; Zhang, F.
2015-01-01
BACKGROUND Congenital scoliosis is a common type of vertebral malformation. Genetic susceptibility has been implicated in congenital scoliosis. METHODS We evaluated 161 Han Chinese persons with sporadic congenital scoliosis, 166 Han Chinese controls, and 2 pedigrees, family members of which had a 16p11.2 deletion, using comparative genomic hybridization, quantitative polymerase-chain-reaction analysis, and DNA sequencing. We carried out tests of replication using an additional series of 76 Han Chinese persons with congenital scoliosis and a multi-center series of 42 persons with 16p11.2 deletions. RESULTS We identified a total of 17 heterozygous TBX6 null mutations in the 161 persons with sporadic congenital scoliosis (11%); we did not observe any null mutations in TBX6 in 166 controls (P<3.8×10−6). These null alleles include copy-number variants (12 instances of a 16p11.2 deletion affecting TBX6) and single-nucleotide variants (1 nonsense and 4 frame-shift mutations). However, the discordant intrafamilial phenotypes of 16p11.2 deletion carriers suggest that heterozygous TBX6 null mutation is insufficient to cause congenital scoliosis. We went on to identify a common TBX6 haplotype as the second risk allele in all 17 carriers of TBX6 null mutations (P<1.1×10−6). Replication studies involving additional persons with congenital scoliosis who carried a deletion affecting TBX6 confirmed this compound inheritance model. In vitro functional assays suggested that the risk haplotype is a hypomorphic allele. Hemivertebrae are characteristic of TBX6-associated congenital scoliosis. CONCLUSIONS Compound inheritance of a rare null mutation and a hypomorphic allele of TBX6 accounted for up to 11% of congenital scoliosis cases in the series that we analyzed. PMID:25564734
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Identification and characterisation of eight novel SERPINA1 Null mutations.
Ferrarotti, Ilaria; Carroll, Tomás P; Ottaviani, Stefania; Fra, Anna M; O'Brien, Geraldine; Molloy, Kevin; Corda, Luciano; Medicina, Daniela; Curran, David R; McElvaney, Noel G; Luisetti, Maurizio
2014-11-26
Alpha-1 antitrypsin (AAT) is the most abundant circulating antiprotease and is a member of the serine protease inhibitor (SERPIN) superfamily. The gene encoding AAT is the highly polymorphic SERPINA1 gene, found at 14q32.1. Mutations in the SERPINA1 gene can lead to AAT deficiency (AATD) which is associated with a substantially increased risk of lung and liver disease. The most common pathogenic AAT variant is Z (Glu342Lys) which causes AAT to misfold and polymerise within hepatocytes and other AAT-producing cells. A group of rare mutations causing AATD, termed Null or Q0, are characterised by a complete absence of AAT in the plasma. While ultra rare, these mutations confer a particularly high risk of emphysema. We performed the determination of AAT serum levels by a rate immune nephelometric method or by immune turbidimetry. The phenotype was determined by isoelectric focusing analysis on agarose gel with specific immunological detection. DNA was isolated from whole peripheral blood or dried blood spot (DBS) samples using a commercial extraction kit. The new mutations were identified by sequencing all coding exons (II-V) of the SERPINA1 gene. We have found eight previously unidentified SERPINA1 Null mutations, named: Q0cork, Q0perugia, Q0brescia, Q0torino, Q0cosenza, Q0pordenone, Q0lampedusa, and Q0dublin . Analysis of clinical characteristics revealed evidence of the recurrence of lung symptoms (dyspnoea, cough) and lung diseases (emphysema, asthma, chronic bronchitis) in M/Null subjects, over 45 years-old, irrespective of smoking. We have added eight more mutations to the list of SERPINA1 Null alleles. This study underlines that the laboratory diagnosis of AATD is not just a matter of degree, because the precise determination of the deficiency and Null alleles carried by an AATD individual may help to evaluate the risk for the lung disease.
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NASA Technical Reports Server (NTRS)
Smilenov, L. B.; Brenner, D. J.; Hall, E. J.
2001-01-01
Subpopulations that are genetically predisposed to radiation-induced cancer could have significant public health consequences. Individuals homozygous for null mutations at the ataxia telangiectasia gene are indeed highly radiosensitive, but their numbers are very small. Ataxia Telangiectasia heterozygotes (1-2% of the population) have been associated with somewhat increased radiosensitivity for some end points, but none directly related to carcinogenesis. Here, intralitter comparisons between wild-type mouse embryo fibroblasts and mouse embryo fibroblasts carrying ataxia telangiectasia mutated (ATM) null mutation indicate that the heterozygous cells are more sensitive to radiation oncogenesis than their normal, litter-matched, counterparts. From these data we suggest that Ataxia Telangiectasia heterozygotes could indeed represent a societally-significant radiosensitive human subpopulation.
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Kudryashova, Elena; Struyk, Arie; Mokhonova, Ekaterina; Cannon, Stephen C; Spencer, Melissa J
2011-10-15
Mutations in tripartite motif protein 32 (TRIM32) are responsible for several hereditary disorders that include limb girdle muscular dystrophy type 2H (LGMD2H), sarcotubular myopathy (STM) and Bardet Biedl syndrome. Most LGMD2H mutations in TRIM32 are clustered in the NHL β-propeller domain at the C-terminus and are predicted to interfere with homodimerization. To get insight into TRIM32's role in the pathogenesis of LGMD2H and to create an accurate model of disease, we have generated a knock-in mouse (T32KI) carrying the c.1465G > A (p.D489N) mutation in murine Trim32 corresponding to the human LGMD2H/STM pathogenic mutation c.1459G > A (p.D487N). Our data indicate that T32KI mice have both a myopathic and a neurogenic phenotype, very similar to the one described in the Trim32-null mice that we created previously. Analysis of Trim32 gene expression in T32KI mice revealed normal mRNA levels, but a severe reduction in mutant TRIM32 (D489N) at the protein level. Our results suggest that the D489N pathogenic mutation destabilizes the protein, leading to its degradation, and results in the same mild myopathic and neurogenic phenotype as that found in Trim32-null mice. Thus, one potential mechanism of LGMD2H might be destabilization of mutated TRIM32 protein leading to a null phenotype.
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Davis, Hayley; Lewis, Annabelle; Spencer-Dene, Bradley; Tateossian, Hilda; Stamp, Gordon; Behrens, Axel; Tomlinson, Ian
2011-01-01
FBXW7 is the substrate recognition component of a SCF-type E3 ubiquitin ligase. It has multiple targets such as Notch1, c-Jun, and cyclin E that function in critical developmental and signalling pathways. Mutations in FBXW7 are often found in many types of cancer. In most cases, these mutations do not inactivate the protein, but are mono-allelic missense changes at specific arginine resides involved in substrate binding. We have hypothesized that FBXW7 mutations are selected in cancers for reasons other than haploinsufficiency or full loss-of-function. Given that the existing mutant Fbxw7 mice carry null alleles, we created a mouse model carrying one of the commonly occurring point mutations (Fbxw7) in the WD40 substrate recognition domain of Fbxw7. Mice heterozygous for this mutation apparently developed normally in utero, died perinatally due to a defect in lung development, and in some cases showed cleft palate and eyelid fusion defects. By comparison, Fbxw7+/− mice were viable and developed normally. Fbxw7−/− animals died of vascular abnormalities at E10.5. We screened known FBXW7 targets for changes in the lungs of the Fbxw7R482Q/+ mice and found Tgif1 and Klf5 to be up-regulated. Fbxw7 alleles are not functionally equivalent to heterozygous or homozygous null alleles, and we propose that they are selected in tumourigenesis because they cause a selective or partial loss of FBXW7 function. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. PMID:21503901
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Takeda, K; Kou, I; Kawakami, N; Yasuhiko, Y; Ogura, Y; Imagawa, E; Miyake, N; Matsumoto, N; Sudo, H; Kotani, T; Nakamura, M; Matsumoto, M; Watanabe, K; Ikegawa, S
2017-11-01
Congenital scoliosis (CS) is a common vertebral malformation with incidence of up to 1 of 1000 births worldwide. Recently, TBX6 has been reported as the first disease gene for CS: about 10% of CS patients are compound heterozygotes of rare null mutations and a common haplotype composed by 3 SNPs in TBX6. Lefebvre et al in this journal reported that 2 patients with spondylocostal dysostosis (SCD), a rare skeletal dysplasia affecting spine and ribs also have TBX6 mutations: 1 carried the microdeletion and a rare missense variant, and another 2 rare missense variants. We investigated the pathogenicity of the 3 missense variants in SCD by a luciferase assay. The results were negative for the proposal of Lefebvre et al. We consider these 2 SCD patients are more probably compound heterozygotes of null mutations and a common risk haplotype just as CS patients with TBX6 mutations. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
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Lombardi, Laura; Schneider, Kevin; Tsukamoto, Michelle; Brody, Stuart
2007-01-01
In Neurospora, the circadian rhythm is expressed as rhythmic conidiation driven by a feedback loop involving the protein products of frq (frequency), wc-1 (white collar-1), and wc-2, known as the frq/wc (FWC) oscillator. Although strains carrying null mutations such as frq10 or wc-2Δ lack a functional FWC oscillator and do not show a rhythm under most conditions, a rhythm can be observed in them by the addition of geraniol or farnesol to the media. Employing this altered media as an assay, the effect of other clock mutations in a frq10- or wc-2Δ-null background can be measured. It was found that the existing clock mutations fall into three classes: (1) those, such as prd-3 or prd-4 or frq1, that showed no effect in a clock null background; (2) those, such as prd-1 or prd-2 or prd-6, that did have a measurable effect in the frq10 background; and (3) those, such as the new mutation ult, that suppressed the frq10 or wc-2Δ effect, i.e., geraniol/farnesol was not required for a visible rhythm. This classification suggests that some of the known clock mutations are part of a broader multioscillator system. PMID:17237512
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Kaufmann, Dieter; Müller, Ralf; Bartelt, Britta; Wolf, Michael; Kunzi-Rapp, Karin; Hanemann, Clemens Oliver; Fahsold, Raimund; Hein, Christian; Vogel, Walther; Assum, Günter
2001-01-01
Spinal neurofibromatosis (SNF) is considered to be an alternative form of neurofibromatosis, showing multiple spinal tumors and café-au-lait macules. Involvement of the neurofibromatosis type 1 (NF1) locus has been demonstrated, by linkage analysis, for three families with SNF. In one of them, a cosegregating frameshift mutation in exon 46 of the NF1 gene was identified. In the present study, we report four individuals from two families who carry NF1 null mutations that would be expected to cause NF1. Three patients have multiple spinal tumors and no café-au-lait macules, and the fourth has no clinical signs of NF1. In the first family, a missense mutation (Leu2067Pro) in NF1 exon 33 was found, and, in the second, a splice-site mutation (IVS31-5A→G) enlarging exon 32 by 4 bp at the 5′ end was found. The latter mutation has also been observed in an unrelated patient with classical NF1. Both NF1 mutations cause a reduction in neurofibromin of ∼50%, with no truncated protein present in the cells. This demonstrates that typical NF1 null mutations can result in a phenotype that is distinct from classical NF1, showing only a small spectrum of the NF1 symptoms, such as multiple spinal tumors, but not completely fitting the current clinical criteria for SNF. We speculate that this phenotype is caused by an unknown modifying gene that compensates for some, but not all, of the effects caused by neurofibromin deficiency. PMID:11704931
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Ghidoni, Roberta; Flocco, Rosa; Paterlini, Anna; Glionna, Michela; Caruana, Loredana; Tonoli, Elisa; Binetti, Giuliano; Benussi, Luisa
2014-01-01
The discovery that mutations in the gene encoding for progranulin (GRN) cause frontotemporal lobar degeneration (FTLD) and other neurodegenerative diseases leading to dementia has brought renewed interest in progranulin and its functions in the central nervous system. Full length progranulin is preserved from cleavage by secretory leukocyte protease inhibitor (SLPI), one of the smallest serine protease inhibitor circulating in plasma. Herein, we investigated the relationship between circulating SLPI and progranulin in affected and unaffected subjects belonging to 26 Italian pedigrees carrying GRN null mutations. In GRN null mutation carriers, we demonstrated: i) an increase of circulating SLPI levels in affected subjects; ii) an age-related upregulation of the serine-protease inhibitor in response to lifetime progranulin shortage; and iii) a delay in the age of onset in subjects with the highest SLPI protein levels. The study of SLPI and its relation to progranulin suggests the existence of unexpected molecular players in progranulin-associated neurodegeneration.
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The impact of p53 protein core domain structural alteration on ovarian cancer survival.
Rose, Stephen L; Robertson, Andrew D; Goodheart, Michael J; Smith, Brian J; DeYoung, Barry R; Buller, Richard E
2003-09-15
Although survival with a p53 missense mutation is highly variable, p53-null mutation is an independent adverse prognostic factor for advanced stage ovarian cancer. By evaluating ovarian cancer survival based upon a structure function analysis of the p53 protein, we tested the hypothesis that not all missense mutations are equivalent. The p53 gene was sequenced from 267 consecutive ovarian cancers. The effect of individual missense mutations on p53 structure was analyzed using the International Agency for Research on Cancer p53 Mutational Database, which specifies the effects of p53 mutations on p53 core domain structure. Mutations in the p53 core domain were classified as either explained or not explained in structural or functional terms by their predicted effects on protein folding, protein-DNA contacts, or mutation in highly conserved residues. Null mutations were classified by their mechanism of origin. Mutations were sequenced from 125 tumors. Effects of 62 of the 82 missense mutations (76%) could be explained by alterations in the p53 protein. Twenty-three (28%) of the explained mutations occurred in highly conserved regions of the p53 core protein. Twenty-two nonsense point mutations and 21 frameshift null mutations were sequenced. Survival was independent of missense mutation type and mechanism of null mutation. The hypothesis that not all missense mutations are equivalent is, therefore, rejected. Furthermore, p53 core domain structural alteration secondary to missense point mutation is not functionally equivalent to a p53-null mutation. The poor prognosis associated with p53-null mutation is independent of the mutation mechanism.
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Spiegel, S; Chiu, A; James, A S; Jentsch, J D; Karlsgodt, K H
2015-11-01
Numerous studies have implicated DTNBP1, the gene encoding dystrobrevin-binding protein or dysbindin, as a candidate risk gene for schizophrenia, though this relationship remains somewhat controversial. Variation in dysbindin, and its location on chromosome 6p, has been associated with cognitive processes, including those relying on a complex system of glutamatergic and dopaminergic interactions. Dysbindin is one of the seven protein subunits that comprise the biogenesis of lysosome-related organelles complex 1 (BLOC-1). Dysbindin protein levels are lower in mice with null mutations in pallidin, another gene in the BLOC-1, and pallidin levels are lower in mice with null mutations in the dysbindin gene, suggesting that multiple subunit proteins must be present to form a functional oligomeric complex. Furthermore, pallidin and dysbindin have similar distribution patterns in a mouse and human brain. Here, we investigated whether the apparent correspondence of pallid and dysbindin at the level of gene expression is also found at the level of behavior. Hypothesizing a mutation leading to underexpression of either of these proteins should show similar phenotypic effects, we studied recognition memory in both strains using the novel object recognition task (NORT) and social novelty recognition task (SNRT). We found that mice with a null mutation in either gene are impaired on SNRT and NORT when compared with wild-type controls. These results support the conclusion that deficits consistent with recognition memory impairment, a cognitive function that is impaired in schizophrenia, result from either pallidin or dysbindin mutations, possibly through degradation of BLOC-1 expression and/or function. © 2015 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.
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Miyasaka, Yuki; Suzuki, Sari; Ohshiba, Yasuhiro; Watanabe, Kei; Sagara, Yoshihiko; Yasuda, Shumpei P; Matsuoka, Kunie; Shitara, Hiroshi; Yonekawa, Hiromichi; Kominami, Ryo; Kikkawa, Yoshiaki
2013-01-01
The waltzer (v) mouse mutant harbors a mutation in Cadherin 23 (Cdh23) and is a model for Usher syndrome type 1D, which is characterized by congenital deafness, vestibular dysfunction, and prepubertal onset of progressive retinitis pigmentosa. In mice, functionally null Cdh23 mutations affect stereociliary morphogenesis and the polarity of both cochlear and vestibular hair cells. In contrast, the murine Cdh23(ahl) allele, which harbors a hypomorphic mutation, causes an increase in susceptibility to age-related hearing loss in many inbred strains. We produced congenic mice by crossing mice carrying the v niigata (Cdh23(v-ngt)) null allele with mice carrying the hypomorphic Cdh23(ahl) allele on the C57BL/6J background, and we then analyzed the animals' balance and hearing phenotypes. Although the Cdh23(v-ngt/ahl) compound heterozygous mice exhibited normal vestibular function, their hearing ability was abnormal: the mice exhibited higher thresholds of auditory brainstem response (ABR) and rapid age-dependent elevation of ABR thresholds compared with Cdh23(ahl/ahl) homozygous mice. We found that the stereocilia developed normally but were progressively disrupted in Cdh23(v-ngt/ahl) mice. In hair cells, CDH23 localizes to the tip links of stereocilia, which are thought to gate the mechanoelectrical transduction channels in hair cells. We hypothesize that the reduction of Cdh23 gene dosage in Cdh23(v-ngt/ahl) mice leads to the degeneration of stereocilia, which consequently reduces tip link tension. These findings indicate that CDH23 plays an important role in the maintenance of tip links during the aging process.
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New tools for targeted disruption of cholinergic synaptic transmission in Drosophila melanogaster.
Mejia, Monica; Heghinian, Mari D; Marí, Frank; Godenschwege, Tanja A
2013-01-01
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels. The α7 subtype of nAChRs is involved in neurological pathologies such as Parkinson's disease, Alzheimer's disease, addiction, epilepsy and autism spectrum disorders. The Drosophila melanogaster α7 (Dα7) has the closest sequence homology to the vertebrate α7 subunit and it can form homopentameric receptors just as the vertebrate counterpart. The Dα7 subunits are essential for the function of the Giant Fiber circuit, which mediates the escape response of the fly. To further characterize the receptor function, we generated different missense mutations in the Dα7 nAChR's ligand binding domain. We characterized the effects of targeted expression of two UAS-constructs carrying a single mutation, D197A and Y195T, as well as a UAS-construct carrying a triple D77T, L117Q, I196P mutation in a Dα7 null mutant and in a wild type background. Expression of the triple mutation was able to restore the function of the circuit in Dα7 null mutants and had no disruptive effects when expressed in wild type. In contrast, both single mutations severely disrupted the synaptic transmission of Dα7-dependent but not glutamatergic or gap junction dependent synapses in wild type background, and did not or only partially rescued the synaptic defects of the null mutant. These observations are consistent with the formation of hybrid receptors, consisting of D197A or Y195T subunits and wild type Dα7 subunits, in which the binding of acetylcholine or acetylcholine-induced conformational changes of the Dα7 receptor are altered and causes inhibition of cholinergic responses. Thus targeted expression of D197A or Y195T can be used to selectively disrupt synaptic transmission of Dα7-dependent synapses in neuronal circuits. Hence, these constructs can be used as tools to study learning and memory or addiction associated behaviors by allowing the manipulation of neuronal processing in the circuits without affecting other cellular signaling.
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New Tools for Targeted Disruption of Cholinergic Synaptic Transmission in Drosophila melanogaster
Mejia, Monica; Heghinian, Mari D.; Marí, Frank; Godenschwege, Tanja A.
2013-01-01
Nicotinic acetylcholine receptors (nAChRs) are pentameric ligand-gated ion channels. The α7 subtype of nAChRs is involved in neurological pathologies such as Parkinson’s disease, Alzheimer’s disease, addiction, epilepsy and autism spectrum disorders. The Drosophila melanogaster α7 (Dα7) has the closest sequence homology to the vertebrate α7 subunit and it can form homopentameric receptors just as the vertebrate counterpart. The Dα7 subunits are essential for the function of the Giant Fiber circuit, which mediates the escape response of the fly. To further characterize the receptor function, we generated different missense mutations in the Dα7 nAChR’s ligand binding domain. We characterized the effects of targeted expression of two UAS-constructs carrying a single mutation, D197A and Y195T, as well as a UAS-construct carrying a triple D77T, L117Q, I196P mutation in a Dα7 null mutant and in a wild type background. Expression of the triple mutation was able to restore the function of the circuit in Dα7 null mutants and had no disruptive effects when expressed in wild type. In contrast, both single mutations severely disrupted the synaptic transmission of Dα7-dependent but not glutamatergic or gap junction dependent synapses in wild type background, and did not or only partially rescued the synaptic defects of the null mutant. These observations are consistent with the formation of hybrid receptors, consisting of D197A or Y195T subunits and wild type Dα7 subunits, in which the binding of acetylcholine or acetylcholine-induced conformational changes of the Dα7 receptor are altered and causes inhibition of cholinergic responses. Thus targeted expression of D197A or Y195T can be used to selectively disrupt synaptic transmission of Dα7-dependent synapses in neuronal circuits. Hence, these constructs can be used as tools to study learning and memory or addiction associated behaviors by allowing the manipulation of neuronal processing in the circuits without affecting other cellular signaling. PMID:23737994
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Feng, Jian Q; Ward, Leanne M; Liu, Shiguang; Lu, Yongbo; Xie, Yixia; Yuan, Baozhi; Yu, Xijie; Rauch, Frank; Davis, Siobhan I; Zhang, Shubin; Rios, Hector; Drezner, Marc K; Quarles, L Darryl; Bonewald, Lynda F; White, Kenneth E
2007-01-01
The osteocyte, a terminally differentiated cell comprising 90%–95% of all bone cells1,2, may have multiple functions, including acting as a mechanosensor in bone (re)modeling3. Dentin matrix protein 1 (encoded by DMP1) is highly expressed in osteocytes4 and, when deleted in mice, results in a hypomineralized bone phenotype5. We investigated the potential for this gene not only to direct skeletal mineralization but also to regulate phosphate (Pi) homeostasis. Both Dmp1- null mice and individuals with a newly identified disorder, autosomal recessive hypophosphatemic rickets, manifest rickets and osteomalacia with isolated renal phosphate-wasting associated with elevated fibroblast growth factor 23 (FGF23) levels and normocalciuria. Mutational analyses showed that autosomal recessive hypophosphatemic rickets family carried a mutation affecting the DMP1 start codon, and a second family carried a 7-bp deletion disrupting the highly conserved DMP1 C terminus. Mechanistic studies using Dmp1-null mice demonstrated that absence of DMP1 results in defective osteocyte maturation and increased FGF23 expression, leading to pathological changes in bone mineralization. Our findings suggest a bone-renal axis that is central to guiding proper mineral metabolism. PMID:17033621
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Brown, SJ; Relton, CL; Liao, H; Zhao, Y; Sandilands, A; McLean, WHI; Cordell, HJ; Reynolds, NJ
2009-01-01
Background Null mutations within the filaggrin gene (FLG) cause ichthyosis vulgaris and are associated with atopic eczema. However, the dermatological features of filaggrin haploinsufficiency have not been clearly defined. Objectives This study investigated the genotype–phenotype association between detailed skin phenotype and FLG genotype data in a population-based cohort of children. Methods Children (n= 792) aged 7–9 years were examined by a dermatologist. Features of ichthyosis vulgaris, atopic eczema and xerosis were recorded and eczema severity graded using the Three Item Severity score. Each child was genotyped for the six most prevalent FLG null mutations (R501X, 2282del4, R2447X, S3247X, 3702delG, 3673delC). Fisher’s exact test was used to compare genotype frequencies in phenotype groups; logistic regression analysis was used to estimate odds ratios and penetrance of the FLG null genotype and a permutation test performed to investigate eczema severity in different genotype groups. Results Ten children in this cohort had ichthyosis vulgaris, of whom five had mild–moderate eczema. The penetrance of FLG null mutations with respect to flexural eczema was 55·6% in individuals with two mutations, 16·3% in individuals with one mutation and 14·2% in wild-type individuals. Summating skin features known to be associated with FLG null mutations (ichthyosis, keratosis pilaris, palmar hyperlinearity and flexural eczema) showed a penetrance of 100% in children with two FLG mutations, 87·8% in children with one FLG mutation and 46·5% in wild-type individuals (P< 0·0001, Fisher exact test). FLG null mutations were associated with more severe eczema (P= 0·0042) but the mean difference was only 1–2 points in severity score. Three distinct patterns of palmar hyperlinearity were observed and these are reported for the first time. Conclusions Filaggrin haploinsufficiency appears to be highly penetrant when all relevant skin features are included in the analysis. FLG null mutations are associated with more severe eczema, but the effect size is small in a population setting. PMID:19681860
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Prewitt, Allison R.; Ghose, Sampa; Frump, Andrea L.; Datta, Arumima; Austin, Eric D.; Kenworthy, Anne K.; de Caestecker, Mark P.
2015-01-01
Hereditary pulmonary arterial hypertension (HPAH) is a rare, fatal disease of the pulmonary vasculature. The majority of HPAH patients inherit mutations in the bone morphogenetic protein type 2 receptor gene (BMPR2), but how these promote pulmonary vascular disease is unclear. HPAH patients have features of pulmonary endothelial cell (PEC) dysfunction including increased vascular permeability and perivascular inflammation associated with decreased PEC barrier function. Recently, frameshift mutations in the caveolar structural protein gene Caveolin-1 (CAV-1) were identified in two patients with non-BMPR2-associated HPAH. Because caveolae regulate endothelial function and vascular permeability, we hypothesized that defects in caveolar function might be a common mechanism by which BMPR2 mutations promote pulmonary vascular disease. To explore this, we isolated PECs from mice carrying heterozygous null Bmpr2 mutations (Bmpr2+/−) similar to those found in the majority of HPAH patients. We show that Bmpr2+/− PECs have increased numbers and intracellular localization of caveolae and caveolar structural proteins CAV-1 and Cavin-1 and that these defects are reversed after blocking endocytosis with dynasore. SRC kinase is also constitutively activated in Bmpr2+/− PECs, and localization of CAV-1 to the plasma membrane is restored after treating Bmpr2+/− PECs with the SRC kinase inhibitor 3-(4-chlorophenyl)-1-(1,1-dimethylethyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (PP2). Late outgrowth endothelial progenitor cells isolated from HPAH patients show similar increased activation of SRC kinase. Moreover, Bmpr2+/− PECs have impaired endothelial barrier function, and barrier function is restored after treatment with PP2. These data suggest that heterozygous null BMPR2 mutations promote SRC-dependent caveolar trafficking defects in PECs and that this may contribute to pulmonary endothelial barrier dysfunction in HPAH patients. PMID:25411245
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Dębińska, Anna; Danielewicz, Hanna; Drabik-Chamerska, Anna; Kalita, Danuta; Boznański, Andrzej
2017-09-01
Loss-of-function mutations in the filaggrin (FLG) gene were identified as a major risk factor for atopic eczema. The aim of the study was to investigate the importance of 4 common FLG null mutations in the susceptibility to atopic eczema and other allergic phenotypes in Polish children population. The FLG mutations were determined in 158 children younger than 2 years of age. All subjects were selected using a detailed questionnaire and blood samples for total and specific IgE measurements were obtained. Cases of atopic eczema were diagnosed according to the criteria of Hanifin and Rajka and skin examination. All FLG mutations were genotyped by real-time PCR assays with a subsequent melting curve analysis using a SimpleProbe® probes. The combined genotype of all 4 mutations (carriage of ≥ 1 FLG mutation) was significantly associated with atopic eczema (p = 0.016). The odds ratio (OR) for individuals carrying 1 of these 4 null mutations was 5.52 (95% CI; 1.11 ÷ 37.12). The significant association between either the combined FLG genotype or 2282del14 deletion and eczema was seen only in the allergic group. The association with asthma was restricted to asthma occurring in the context of eczema (OR, 6.27; 95% CI, 0.89 ÷ 53.56; p = 0.042). Our study confirms the previous findings that FLG mutations are strongly associated with atopic eczema and confer a significant risk of allergic sensitization and asthma in the context of eczema. These results underline the role of the epidermal barrier and filaggrin insufficiency in the pathogenesis of atopic eczema and eczema-associated asthma.
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Giovannelli, Gaia; Giacomazzi, Giorgia; Grosemans, Hanne; Sampaolesi, Maurilio
2018-02-24
Limb-girdle muscular dystrophy type 2E (LGMD2E) is caused by mutations in the β-sarcoglycan gene, which is expressed in skeletal, cardiac, and smooth muscles. β-Sarcoglycan-deficient (Sgcb-null) mice develop severe muscular dystrophy and cardiomyopathy with focal areas of necrosis. In this study we performed morphological (histological and cellular characterization) and functional (isometric tetanic force and fatigue) analyses in dystrophic mice. Comparison studies were carried out in 1-month-old (clinical onset of the disease) and 7-month-old control mice (C57Bl/6J, Rag2/γc-null) and immunocompetent and immunodeficient dystrophic mice (Sgcb-null and Sgcb/Rag2/γc-null, respectively). We found that the lack of an immunological system resulted in an increase of calcification in striated muscles without impairing extensor digitorum longus muscle performance. Sgcb/Rag2/γc-null muscles showed a significant reduction of alkaline phosphate-positive mesoangioblasts. The immunological system counteracts skeletal muscle degeneration in the murine model of LGMD2E. Muscle Nerve, 2018. © 2018 The Authors. Muscle & Nerve Published by Wiley Periodicals, Inc.
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Ghosh, Soma; Sur, Surojit; Yerram, Sashidhar R.; Rago, Carlo; Bhunia, Anil K.; Hossain, M. Zulfiquer; Paun, Bogdan C.; Ren, Yunzhao R.; Iacobuzio-Donahue, Christine A.; Azad, Nilofer A.; Kern, Scott E.
2014-01-01
Large-magnitude numerical distinctions (>10-fold) among drug responses of genetically contrasting cancers were crucial for guiding the development of some targeted therapies. Similar strategies brought epidemiological clues and prevention goals for genetic diseases. Such numerical guides, however, were incomplete or low magnitude for Fanconi anemia pathway (FANC) gene mutations relevant to cancer in FANC-mutation carriers (heterozygotes). We generated a four-gene FANC-null cancer panel, including the engineering of new PALB2/FANCN-null cancer cells by homologous recombination. A characteristic matching of FANCC-null, FANCG-null, BRCA2/FANCD1-null, and PALB2/FANCN-null phenotypes was confirmed by uniform tumor regression on single-dose cross-linker therapy in mice and by shared chemical hypersensitivities to various inter-strand cross-linking agents and γ-radiation in vitro. Some compounds, however, had contrasting magnitudes of sensitivity; a strikingly high (19- to 22-fold) hypersensitivity was seen among PALB2-null and BRCA2-null cells for the ethanol metabolite, acetaldehyde, associated with widespread chromosomal breakage at a concentration not producing breaks in parental cells. Because FANC-defective cancer cells can share or differ in their chemical sensitivities, patterns of selective hypersensitivity hold implications for the evolutionary understanding of this pathway. Clinical decisions for cancer-relevant prevention and management of FANC-mutation carriers could be modified by expanded studies of high-magnitude sensitivities. PMID:24200853
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Takeda, Kazuki; Kou, Ikuyo; Kawakami, Noriaki; Iida, Aritoshi; Nakajima, Masahiro; Ogura, Yoji; Imagawa, Eri; Miyake, Noriko; Matsumoto, Naomichi; Yasuhiko, Yukuto; Sudo, Hideki; Kotani, Toshiaki; Nakamura, Masaya; Matsumoto, Morio; Watanabe, Kota; Ikegawa, Shiro
2017-03-01
Congenital scoliosis (CS) occurs as a result of vertebral malformations and has an incidence of 0.5-1/1,000 births. Recently, TBX6 on chromosome 16p11.2 was reported as a disease gene for CS; about 10% of Chinese CS patients were compound heterozygotes for rare null mutations and a common haplotype defined by three SNPs in TBX6. All patients had hemivertebrae. We recruited 94 Japanese CS patients, investigated the TBX6 locus for both mutations and the risk haplotype, examined transcriptional activities of mutant TBX6 in vitro, and evaluated clinical and radiographic features. We identified TBX6 null mutations in nine patients, including a missense mutation that had a loss of function in vitro. All had the risk haplotype in the opposite allele. One of the mutations showed dominant negative effect. Although all Chinese patients had one or more hemivertebrae, two Japanese patients did not have hemivertebra. The compound heterozygosity of null mutations and the common risk haplotype in TBX6 also causes CS in Japanese patients with similar incidence. Hemivertebra was not a specific type of spinal malformation in TBX6-associated CS (TACS). A heterozygous TBX6 loss-of-function mutation has been reported in a family with autosomal-dominant spondylocostal dysostosis, but it may represent a spectrum of the same disease with TACS. © 2017 WILEY PERIODICALS, INC.
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Rhnull syndrome: identification of a novel mutation in RHce.
Rosa, K A; Reid, M E; Lomas-Francis, C; Powell, V I; Costa, F F; Stinghen, S T; Watanabe, A M; Carboni, E K; Baldon, J P; Jucksch, M M F; Castilho, L
2005-11-01
The deficiency of Rh proteins on red blood cells (RBCs) from individuals of the Rh(null) amorph type are the result of homozygosity for a silent RHCE in cis with a deleted RHD. A novel mutation in RHce was identified in two Caucasian Brazilian girls with the amorph type of Rh(null) who were born to parents who were first cousins. RBCs from the Rh(null) sisters and from family members were analyzed by serology and flow cytometry with specific antibodies. Genomic DNA and transcripts were tested by polymerase chain reaction and sequence analysis. Rh(null) RBCs were nonreactive with anti-Rh and anti-LW. Molecular analyses showed a deletion of RHD and of one nucleotide (960/963; GGGG-->GGG) in exon 7 of the RHce. This deletion introduced a frameshift after Gly321, a new C-terminal sequence, and a premature stop codon, resulting in a shorter predicted protein with 357 amino acids. The detection of a unique RHce transcript indicated that the two sisters were homozygous, whereas the other family members were heterozygous for the mutation. A novel mutation resulting in the amorph Rh(null) with loss of Rh antigen expression is described.
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Singh, Seram Anil; Ghosh, Sankar Kumar
2017-09-26
Multiple genetic and environmental factors and their interaction are believed to contribute in the pathogenesis of Nasopharyngeal Cancer (NPC). We investigate the role of Metabolic Phase I (CYPs) and Phase II (GSTs) gene polymorphisms, gene-gene and gene-environmental interaction in modulating the susceptibility to NPC in Northeast India. To determine the association of metabolic gene polymorphisms and environmental habits, 123 cases and 189 controls blood/swab samples were used for PCR and confirmed by Sanger sequencing. Analysis for GSTM1 and GSTT1 gene polymorphism was done by multiplex PCR. The T3801C in the 3'- flanking region of CYP1A1 gene was detected by PCR-RFLP method. The Logistic regression analysis was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI). The GSTM1 null genotype alone (OR = 2.76) was significantly associated with NPC risk (P < 0.0001). The combinations of GSTM1 null and GSTT1 null genotypes also higher, 3.77 fold (P < 0.0001), risk of NPC, while GSTM1 null genotype along with CYP1A1 T3801C TC + CC genotype had 3.22 (P = 0.001) fold risk. The most remarkable risk was seen among individual carrying GSTM1 null, GSTT1 null genotypes and CYP1A1 T3801C TC + CC genotypes (OR = 5.71, P = 0.001). Further; analyses demonstrate an enhanced risk of NPC in smoked meat (OR = 5.56, P < 0.0001) and fermented fish consumers (OR = 5.73, P < 0.0001) carrying GSTM1 null genotype. An elevated risk of NPC was noted in smokers (OR = 12.67, P < 0.0001) and chewers (OR = 5.68, P < 0.0001) with GSTM1 null genotype. However, smokers had the highest risk of NPC among individuals carrying GSTT1 null genotype (OR = 4.46, P = 0.001) or CYP1A1 T3801C TC + CC genotype (OR = 7.13, P < 0.0001). The association of null genotypes and mutations of metabolic neutralizing genes along with the environmental habits (tobacco smokers and chewers, smoke meat, fermented fishes) can be used as a possible biomarker for early detection and preventive measure of NPC.
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GATA2 null mutation associated with incomplete penetrance in a family with Emberger syndrome.
Brambila-Tapia, Aniel Jessica Leticia; García-Ortiz, José Elías; Brouillard, Pascal; Nguyen, Ha-Long; Vikkula, Miikka; Ríos-González, Blanca Estela; Sandoval-Muñiz, Roberto de Jesús; Sandoval-Talamantes, Ana Karen; Bobadilla-Morales, Lucina; Corona-Rivera, Jorge Román; Arnaud-Lopez, Lisette
2017-09-01
GATA2 mutations are associated with several conditions, including Emberger syndrome which is the association of primary lymphedema with hematological anomalies and an increased risk for myelodysplasia and leukemia. To describe a family with Emberger syndrome with incomplete penetrance. A DNA sequencing of GATA2 gene was performed in the parents and offspring (five individuals in total). The family consisted of 5 individuals with a GATA2 null mutation (c.130G>T, p.Glu44*); three of them were affected (two of which were deceased) while two remained unaffected at the age of 40 and 13 years old. The three affected siblings (two boys and one girl) presented with lymphedema of the lower limbs, recurrent warts, epistaxis and recurrent infections. Two died due to hematological abnormalities (AML and pancytopenia). In contrast, the two other family members who carry the same mutation (the mother and one brother) have not presented any symptoms and their blood tests remain normal. Incomplete penetrance may indicate that GATA2 haploinsufficiency is not enough to produce the phenotype of Emberger syndrome. It could be useful to perform whole exome or genome sequencing, in cases where incomplete penetrance or high variable expressivity is described, in order to probably identify specific gene interactions that drastically modify the phenotype. In addition, skewed gene expression by an epigenetic mechanism of gene regulation should also be considered.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Sakuma, Hitoshi; Inana, G.; Murakami, Akira
1995-05-20
ROM1 is a 351-amino-acid, 37-kDa outer segment membrane protein of rod photoreceptors. ROM1 is related to peripherin/RDS, another outer segment membrane protein found in both rods and cones. The precise function of ROM1 or peripherin/RDS is not known, but they have been suggested to play important roles in the function and/or structure of the rod photoreceptor outer segment disks. A recent report implicated ROM1 in disease by suggesting that RP can be caused by a heterozygous null mutation in ROM1 but only in combination with another heterozygous mutation in peripherin/RDS. Screening of the ROM1 gene using polymerase chain reaction amplification,more » denaturing gradient gel electrophoresis, and direct DNA sequencing identified the same heterozygous putative null mutation in a family with RP.« less
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Ghosh, Soma; Sur, Surojit; Yerram, Sashidhar R; Rago, Carlo; Bhunia, Anil K; Hossain, M Zulfiquer; Paun, Bogdan C; Ren, Yunzhao R; Iacobuzio-Donahue, Christine A; Azad, Nilofer A; Kern, Scott E
2014-01-01
Large-magnitude numerical distinctions (>10-fold) among drug responses of genetically contrasting cancers were crucial for guiding the development of some targeted therapies. Similar strategies brought epidemiological clues and prevention goals for genetic diseases. Such numerical guides, however, were incomplete or low magnitude for Fanconi anemia pathway (FANC) gene mutations relevant to cancer in FANC-mutation carriers (heterozygotes). We generated a four-gene FANC-null cancer panel, including the engineering of new PALB2/FANCN-null cancer cells by homologous recombination. A characteristic matching of FANCC-null, FANCG-null, BRCA2/FANCD1-null, and PALB2/FANCN-null phenotypes was confirmed by uniform tumor regression on single-dose cross-linker therapy in mice and by shared chemical hypersensitivities to various inter-strand cross-linking agents and γ-radiation in vitro. Some compounds, however, had contrasting magnitudes of sensitivity; a strikingly high (19- to 22-fold) hypersensitivity was seen among PALB2-null and BRCA2-null cells for the ethanol metabolite, acetaldehyde, associated with widespread chromosomal breakage at a concentration not producing breaks in parental cells. Because FANC-defective cancer cells can share or differ in their chemical sensitivities, patterns of selective hypersensitivity hold implications for the evolutionary understanding of this pathway. Clinical decisions for cancer-relevant prevention and management of FANC-mutation carriers could be modified by expanded studies of high-magnitude sensitivities. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
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Loss of ATM kinase activity leads to embryonic lethality in mice.
Daniel, Jeremy A; Pellegrini, Manuela; Lee, Baeck-Seung; Guo, Zhi; Filsuf, Darius; Belkina, Natalya V; You, Zhongsheng; Paull, Tanya T; Sleckman, Barry P; Feigenbaum, Lionel; Nussenzweig, André
2012-08-06
Ataxia telangiectasia (A-T) mutated (ATM) is a key deoxyribonucleic acid (DNA) damage signaling kinase that regulates DNA repair, cell cycle checkpoints, and apoptosis. The majority of patients with A-T, a cancer-prone neurodegenerative disease, present with null mutations in Atm. To determine whether the functions of ATM are mediated solely by its kinase activity, we generated two mouse models containing single, catalytically inactivating point mutations in Atm. In this paper, we show that, in contrast to Atm-null mice, both D2899A and Q2740P mutations cause early embryonic lethality in mice, without displaying dominant-negative interfering activity. Using conditional deletion, we find that the D2899A mutation in adult mice behaves largely similar to Atm-null cells but shows greater deficiency in homologous recombination (HR) as measured by hypersensitivity to poly (adenosine diphosphate-ribose) polymerase inhibition and increased genomic instability. These results may explain why missense mutations with no detectable kinase activity are rarely found in patients with classical A-T. We propose that ATM kinase-inactive missense mutations, unless otherwise compensated for, interfere with HR during embryogenesis.
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Chatterjee, Ranjini; Millard, Cynthia Sanville; Champion, Kathleen; Clark, David P.; Donnelly, Mark I.
2001-01-01
Escherichia coli NZN111 is blocked in the ability to grow fermentatively on glucose but gave rise spontaneously to a mutant that had this ability. The mutant carries out a balanced fermentation of glucose to give approximately 1 mol of succinate, 0.5 mol of acetate, and 0.5 mol of ethanol per mol of glucose. The causative mutation was mapped to the ptsG gene, which encodes the membrane-bound, glucose-specific permease of the phosphotransferase system, protein EIICBglc. Replacement of the chromosomal ptsG gene with an insertionally inactivated form also restored growth on glucose and resulted in the same distribution of fermentation products. The physiological characteristics of the spontaneous and null mutants were consistent with loss of function of the ptsG gene product; the mutants possessed greatly reduced glucose phosphotransferase activity and lacked normal glucose repression. Introduction of the null mutant into strains not blocked in the ability to ferment glucose also increased succinate production in those strains. This phenomenon was widespread, occurring in different lineages of E. coli, including E. coli B. PMID:11133439
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Mutations in Prickle Orthologs Cause Seizures in Flies, Mice, and Humans
Tao, Hirotaka; Manak, J. Robert; Sowers, Levi; Mei, Xue; Kiyonari, Hiroshi; Abe, Takaya; Dahdaleh, Nader S.; Yang, Tian; Wu, Shu; Chen, Shan; Fox, Mark H.; Gurnett, Christina; Montine, Thomas; Bird, Thomas; Shaffer, Lisa G.; Rosenfeld, Jill A.; McConnell, Juliann; Madan-Khetarpal, Suneeta; Berry-Kravis, Elizabeth; Griesbach, Hilary; Saneto, Russell P.; Scott, Matthew P.; Antic, Dragana; Reed, Jordan; Boland, Riley; Ehaideb, Salleh N.; El-Shanti, Hatem; Mahajan, Vinit B.; Ferguson, Polly J.; Axelrod, Jeffrey D.; Lehesjoki, Anna-Elina; Fritzsch, Bernd; Slusarski, Diane C.; Wemmie, John; Ueno, Naoto; Bassuk, Alexander G.
2011-01-01
Epilepsy is heritable, yet few causative gene mutations have been identified, and thus far no human epilepsy gene mutations have been found to produce seizures in invertebrates. Here we show that mutations in prickle genes are associated with seizures in humans, mice, and flies. We identified human epilepsy patients with heterozygous mutations in either PRICKLE1 or PRICKLE2. In overexpression assays in zebrafish, prickle mutations resulted in aberrant prickle function. A seizure phenotype was present in the Prickle1-null mutant mouse, two Prickle1 point mutant (missense and nonsense) mice, and a Prickle2-null mutant mouse. Drosophila with prickle mutations displayed seizures that were responsive to anti-epileptic medication, and homozygous mutant embryos showed neuronal defects. These results suggest that prickle mutations have caused seizures throughout evolution. PMID:21276947
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Bishop, Kathleen A; Harrington, Anne; Kouranova, Evguenia; Weinstein, Edward J; Rosen, Clifford J; Cui, Xiaoxia; Liaw, Lucy
2016-07-07
Targeted gene mutation in the mouse is a primary strategy to understand gene function and relation to phenotype. The Knockout Mouse Project (KOMP) had an initial goal to develop a public resource of mouse embryonic stem (ES) cell clones that carry null mutations in all genes. Indeed, many useful novel mouse models have been generated from publically accessible targeted mouse ES cell lines. However, there are limitations, including incorrect targeting or cassette structure, and difficulties with germline transmission of the allele from chimeric mice. In our experience, using a small sample of targeted ES cell clones, we were successful ∼50% of the time in generating germline transmission of a correctly targeted allele. With the advent of CRISPR/Cas9 as a mouse genome modification tool, we assessed the efficiency of creating a conditional targeted allele in one gene, dedicator of cytokinesis 7 (Dock7), for which we were unsuccessful in generating a null allele using a KOMP targeted ES cell clone. The strategy was to insert loxP sites to flank either exons 3 and 4, or exons 3 through 7. By coinjecting Cas9 mRNA, validated sgRNAs, and oligonucleotide donors into fertilized eggs from C57BL/6J mice, we obtained a variety of alleles, including mice homozygous for the null alleles mediated by nonhomologous end joining, alleles with one of the two desired loxP sites, and correctly targeted alleles with both loxP sites. We also found frequent mutations in the inserted loxP sequence, which is partly attributable to the heterogeneity in the original oligonucleotide preparation. Copyright © 2016 Bishop et al.
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López-Rubio, Salvador; Chacon-Camacho, Oscar F.; Matsui, Rodrigo; Guadarrama-Vallejo, Dalia; Astiazarán, Mirena C.
2018-01-01
Purpose To describe the retinal clinical features of a group of Mexican patients with Stargardt disease carrying the uncommon p.Ala1773Val founder mutation in ABCA4. Methods Ten patients carrying the p.Ala1773Val mutation, nine of them homozygously, were included. Visual function studies included best-corrected visual acuity, electroretinography, Goldmann kinetic visual fields, and full-field electroretinography (ERG). In addition, imaging studies, such as optical coherence tomography (OCT), short-wave autofluorescence imaging, and quantitative analyses of hypofluorescence, were performed in each patient. Results Best-corrected visual acuities ranged from 20/200 to 4/200. The median age of the patients at diagnosis was 23.3 years. The majority of the patients had photophobia and nyctalopia, and were classified as Fishman stage 4 (widespread choriocapillaris atrophy, resorption of flecks, and greatly reduced ERG amplitudes). An atypical retinal pigmentation pattern was observed in the patients, and the majority showed cone-rod dystrophy on full-field ERG. In vivo retinal microstructure assessment with OCT demonstrated central retinal thinning, variable loss of photoreceptors, and three different patterns of structural retinal degeneration. Two dissimilar patterns of abnormal autofluorescence were observed. No apparent age-related differences in the pattern of retinal degeneration were observed. Conclusions The results indicate that this particular mutation in ABCA4 is associated with a severe retinal phenotype and thus, could be classified as null. Careful phenotyping of patients carrying specific mutations in ABCA4 is essential to enhance our understanding of disease expression linked to particular mutations and the resulting genotype–phenotype correlations. PMID:29422768
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Mignot, Cyril; Lambert, Laetitia; Pasquier, Laurent; Bienvenu, Thierry; Delahaye-Duriez, Andrée; Keren, Boris; Lefranc, Jérémie; Saunier, Aline; Allou, Lila; Roth, Virginie; Valduga, Mylène; Moustaïne, Aissa; Auvin, Stéphane; Barrey, Catherine; Chantot-Bastaraud, Sandra; Lebrun, Nicolas; Moutard, Marie-Laure; Nougues, Marie-Christine; Vermersch, Anne-Isabelle; Héron, Bénédicte; Pipiras, Eva; Héron, Delphine; Olivier-Faivre, Laurence; Guéant, Jean-Louis; Jonveaux, Philippe; Philippe, Christophe
2015-01-01
Homozygous mutations in WWOX were reported in eight individuals of two families with autosomal recessive spinocerebellar ataxia type 12 and in two siblings with infantile epileptic encephalopathy (IEE), including one who deceased prior to DNA sampling. By combining array comparative genomic hybridisation, targeted Sanger sequencing and next generation sequencing, we identified five further patients from four families with IEE due to biallelic alterations of WWOX. We identified eight deleterious WWOX alleles consisting in four deletions, a four base-pair frameshifting deletion, one missense and two nonsense mutations. Genotype-phenotype correlation emerges from the seven reported families. The phenotype in four patients carrying two predicted null alleles was characterised by (1) little if any psychomotor acquisitions, poor spontaneous motility and absent eye contact from birth, (2) pharmacoresistant epilepsy starting in the 1st weeks of life, (3) possible retinal degeneration, acquired microcephaly and premature death. This contrasted with the less severe autosomal recessive spinocerebellar ataxia type 12 phenotype due to hypomorphic alleles. In line with this correlation, the phenotype in two siblings carrying a null allele and a missense mutation was intermediate. Our results obtained by a combination of different molecular techniques undoubtedly incriminate WWOX as a gene for recessive IEE and illustrate the usefulness of high throughput data mining for the identification of genes for rare autosomal recessive disorders. The structure of the WWOX locus encompassing the FRA16D fragile site might explain why constitutive deletions are recurrently reported in genetic databases, suggesting that WWOX-related encephalopathies, although likely rare, may not be exceptional. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
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Stevens, Karen E; Choo, Kevin S; Stitzel, Jerry A; Marks, Michael J; Adams, Catherine E
2014-03-13
Perinatal choline supplementation has produced several benefits in rodent models, from improved learning and memory to protection from the behavioral effects of fetal alcohol exposure. We have shown that supplemented choline through gestation and lactation produces long-term improvement in deficient sensory inhibition in DBA/2 mice which models a similar deficit in schizophrenia patients. The present study extends that research by feeding normal or supplemented choline diets to DBA/2 mice carrying the null mutation for the α7 nicotinic receptor gene (Chrna7). DBA/2 mice heterozygotic for Chrna7 were bred together. Dams were placed on supplemented (5 gm/kg diet) or normal (1.1 gm/kg diet) choline at mating and remained on the specific diet until offspring weaning. Thereafter, offspring were fed standard rodent chow. Adult offspring were assessed for sensory inhibition. Brains were obtained to ascertain hippocampal α7 nicotinic receptor levels. Choline-supplemented mice heterozygotic or null-mutant for Chrna7 failed to show improvement in sensory inhibition. Only wildtype choline-supplemented mice showed improvement with the effect solely through a decrease in test amplitude. This supports the hypothesis that gestational-choline supplementation is acting through the α7 nicotinic receptor to improve sensory inhibition. Although there was a significant gene-dose-related change in hippocampal α7 receptor numbers, binding studies did not reveal any choline-dose-related change in binding in any hippocampal region, the interaction being driven by a significant genotype main effect (wildtype>heterozygote>null mutant). These data parallel a human study wherein the offspring of pregnant women receiving choline supplementation during gestation, showed better sensory inhibition than offspring of women on placebo. Published by Elsevier B.V.
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Stevens, Karen E.; Choo, Kevin S.; Stitzel, Jerry A.; Marks, Michael J.; Adams, Catherine E.
2014-01-01
Perinatal choline supplementation has produced several benefits in rodent models, from improved learning and memory to protection from the behavioral effects of fetal alcohol exposure. We have shown that supplemented choline through gestation and lactation produces long-term improvement in deficient sensory inhibition in DBA/2 mice which models a similar deficit in schizophrenia patients. The present study extends that research by feeding normal or supplemented choline diets to DBA/2 mice carrying the null mutation for the α7 nicotinic receptor gene (Chrna7). DBA/2 mice heterozygotic for Chrna7 were bred together. Dams were placed on supplemented (5 gm/kg diet) or normal (1.1 gm/kg diet) choline at mating and remained on the specific diet until offspring weaning. Thereafter, offspring were fed standard rodent chow. Adult offspring were assessed for sensory inhibition. Brains were obtained to ascertain hippocampal α7 nicotinic receptor levels. Choline-supplemented mice heterozygotic or null-mutant for Chrna7 failed to show improvement in sensory inhibition. Only wildtype choline-supplemented mice showed improvement with the effect solely through a decrease in test amplitude. This supports the hypothesis that gestational-choline supplementation is acting through the α7 nicotinic receptor to improve sensory inhibition. Although there was a significant gene-dose-related change in hippocampal α7 receptor numbers, binding studies did not reveal any choline-dose-related change in binding in any hippocampal region, the interaction being driven by a significant genotype main effect (wildtype>heterozygote>null mutant). These data parallel a human study wherein the offspring of pregnant women receiving choline supplementation during gestation, showed better sensory inhibition than offspring of women on placebo. PMID:24462939
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Kiong, Tiong Sieh; Salem, S. Balasem; Paw, Johnny Koh Siaw; Sankar, K. Prajindra
2014-01-01
In smart antenna applications, the adaptive beamforming technique is used to cancel interfering signals (placing nulls) and produce or steer a strong beam toward the target signal according to the calculated weight vectors. Minimum variance distortionless response (MVDR) beamforming is capable of determining the weight vectors for beam steering; however, its nulling level on the interference sources remains unsatisfactory. Beamforming can be considered as an optimization problem, such that optimal weight vector should be obtained through computation. Hence, in this paper, a new dynamic mutated artificial immune system (DM-AIS) is proposed to enhance MVDR beamforming for controlling the null steering of interference and increase the signal to interference noise ratio (SINR) for wanted signals. PMID:25003136
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Kiong, Tiong Sieh; Salem, S Balasem; Paw, Johnny Koh Siaw; Sankar, K Prajindra; Darzi, Soodabeh
2014-01-01
In smart antenna applications, the adaptive beamforming technique is used to cancel interfering signals (placing nulls) and produce or steer a strong beam toward the target signal according to the calculated weight vectors. Minimum variance distortionless response (MVDR) beamforming is capable of determining the weight vectors for beam steering; however, its nulling level on the interference sources remains unsatisfactory. Beamforming can be considered as an optimization problem, such that optimal weight vector should be obtained through computation. Hence, in this paper, a new dynamic mutated artificial immune system (DM-AIS) is proposed to enhance MVDR beamforming for controlling the null steering of interference and increase the signal to interference noise ratio (SINR) for wanted signals.
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Mutations in the PDE6B gene in autosomal recessive retinitis pigmentosa
DOE Office of Scientific and Technical Information (OSTI.GOV)
Danciger, M.; Blaney, J.; Gao, Y.Q.
1995-11-01
We have studied 24 small families with presumed autosomal recessive inheritance of retinitis pigmentosa by a combination of haplotype analysis and exon screening. Initial analysis of the families was made with a dinucleotide repeat polymorphism adjacent to the gene for rod cGMP-phosphodiesterase (PDE6B). This was followed by denaturing gradient gel electrophoresis (DGGE) and single-strand conformation polymorphism electrophoresis (SSCPE) of the 22 exons and a portion of the 5{prime} untranslated region of the PDE6B gene in the probands of each family in which the PDE6B locus could not be ruled out from segregating with disease. Two probands were found with compoundmore » heterozygous mutations: Gly576Asp and His620(1-bp del) mutations were present in one proband, and a Lys706X null mutation and an AG to AT splice acceptor site mutation in intron 2 were present in the other. Only the affecteds of each of the two families carried both corresponding mutations. 29 refs., 3 figs., 1 tab.« less
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Ghidoni, Roberta; Stoppani, Elena; Rossi, Giacomina; Piccoli, Elena; Albertini, Valentina; Paterlini, Anna; Glionna, Michela; Pegoiani, Eleonora; Agnati, Luigi F; Fenoglio, Chiara; Scarpini, Elio; Galimberti, Daniela; Morbin, Michela; Tagliavini, Fabrizio; Binetti, Giuliano; Benussi, Luisa
2012-01-01
Recently, attention was drawn to a role for progranulin in the central nervous system with the identification of mutations in the progranulin gene (GRN) as an important cause of frontotemporal lobar degeneration. GRN mutations are associated with a strong reduction of circulating progranulin and widely variable clinical phenotypes: thus, the dosage of plasma progranulin is a useful tool for a quick and inexpensive large-scale screening of carriers of GRN mutations. To establish the best cutoff threshold for normal versus abnormal levels of plasma progranulin. 309 cognitively healthy controls (25-87 years of age), 72 affected and unaffected GRN+ null mutation carriers (24-86 years of age), 3 affected GRN missense mutation carriers, 342 patients with neurodegenerative diseases and 293 subjects with mild cognitive impairment were enrolled at the Memory Clinic, IRCCS S. Giovanni di Dio-Fatebenefratelli, Brescia, Italy, and at the Alzheimer Unit, Ospedale Maggiore Policlinico and IRCCS Istituto Neurologico C. Besta, Milan, Italy. Plasma progranulin levels were measured using an ELISA kit (AdipoGen Inc., Seoul, Korea). Plasma progranulin did not correlate with age, gender or body mass index. We established a new plasma progranulin protein cutoff level of 61.55 ng/ml that identifies, with a specificity of 99.6% and a sensitivity of 95.8%, null mutation carriers among subjects attending to a memory clinic. Affected and unaffected GRN null mutation carriers did not differ in terms of circulating progranulin protein (p = 0.686). A significant disease anticipation was observed in GRN+ subjects with the lowest progranulin levels. We propose a new plasma progranulin protein cutoff level useful for clinical practice. Copyright © 2011 S. Karger AG, Basel.
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Molecular analysis of mutations in DNA polymerase η in xeroderma pigmentosum-variant patients
Broughton, Bernard C.; Cordonnier, Agnes; Kleijer, Wim J.; Jaspers, Nicolaas G. J.; Fawcett, Heather; Raams, Anja; Garritsen, Victor H.; Stary, Anne; Avril, Marie-Françoise; Boudsocq, François; Masutani, Chikahide; Hanaoka, Fumio; Fuchs, Robert P.; Sarasin, Alain; Lehmann, Alan R.
2002-01-01
Xeroderma pigmentosum variant (XP-V) cells are deficient in their ability to synthesize intact daughter DNA strands after UV irradiation. This deficiency results from mutations in the gene encoding DNA polymerase η, which is required for effecting translesion synthesis (TLS) past UV photoproducts. We have developed a simple cellular procedure to identify XP-V cell strains, and have subsequently analyzed the mutations in 21 patients with XP-V. The 16 mutations that we have identified fall into three categories. Many of them result in severe truncations of the protein and are effectively null alleles. However, we have also identified five missense mutations located in the conserved catalytic domain of the protein. Extracts of cells falling into these two categories are defective in the ability to carry out TLS past sites of DNA damage. Three mutations cause truncations at the C terminus such that the catalytic domains are intact, and extracts from these cells are able to carry out TLS. From our previous work, however, we anticipate that protein in these cells will not be localized in the nucleus nor will it be relocalized into replication foci during DNA replication. The spectrum of both missense and truncating mutations is markedly skewed toward the N-terminal half of the protein. Two of the missense mutations are predicted to affect the interaction with DNA, the others are likely to disrupt the three-dimensional structure of the protein. There is a wide variability in clinical features among patients, which is not obviously related to the site or type of mutation. PMID:11773631
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Tosco, A; De Gregorio, F; Esposito, S; De Stefano, D; Sana, I; Ferrari, E; Sepe, A; Salvadori, L; Buonpensiero, P; Di Pasqua, A; Grassia, R; Leone, C A; Guido, S; De Rosa, G; Lusa, S; Bona, G; Stoll, G; Maiuri, M C; Mehta, A; Kroemer, G; Maiuri, L; Raia, V
2016-08-01
We previously reported that the combination of two safe proteostasis regulators, cysteamine and epigallocatechin gallate (EGCG), can be used to improve deficient expression of the cystic fibrosis transmembrane conductance regulator (CFTR) in patients homozygous for the CFTR Phe508del mutation. Here we provide the proof-of-concept that this combination treatment restored CFTR function and reduced lung inflammation (P<0.001) in Phe508del/Phe508del or Phe508del/null-Cftr (but not in Cftr-null mice), provided that such mice were autophagy-competent. Primary nasal cells from patients bearing different class II CFTR mutations, either in homozygous or compound heterozygous form, responded to the treatment in vitro. We assessed individual responses to cysteamine plus EGCG in a single-centre, open-label phase-2 trial. The combination treatment decreased sweat chloride from baseline, increased both CFTR protein and function in nasal cells, restored autophagy in such cells, decreased CXCL8 and TNF-α in the sputum, and tended to improve respiratory function. These positive effects were particularly strong in patients carrying Phe508del CFTR mutations in homozygosity or heterozygosity. However, a fraction of patients bearing other CFTR mutations failed to respond to therapy. Importantly, the same patients whose primary nasal brushed cells did not respond to cysteamine plus EGCG in vitro also exhibited deficient therapeutic responses in vivo. Altogether, these results suggest that the combination treatment of cysteamine plus EGCG acts 'on-target' because it can only rescue CFTR function when autophagy is functional (in mice) and improves CFTR function when a rescuable protein is expressed (in mice and men). These results should spur the further clinical development of the combination treatment.
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Tosco, A; De Gregorio, F; Esposito, S; De Stefano, D; Sana, I; Ferrari, E; Sepe, A; Salvadori, L; Buonpensiero, P; Di Pasqua, A; Grassia, R; Leone, C A; Guido, S; De Rosa, G; Lusa, S; Bona, G; Stoll, G; Maiuri, M C; Mehta, A; Kroemer, G; Maiuri, L; Raia, V
2016-01-01
We previously reported that the combination of two safe proteostasis regulators, cysteamine and epigallocatechin gallate (EGCG), can be used to improve deficient expression of the cystic fibrosis transmembrane conductance regulator (CFTR) in patients homozygous for the CFTR Phe508del mutation. Here we provide the proof-of-concept that this combination treatment restored CFTR function and reduced lung inflammation (P<0.001) in Phe508del/Phe508del or Phe508del/null-Cftr (but not in Cftr-null mice), provided that such mice were autophagy-competent. Primary nasal cells from patients bearing different class II CFTR mutations, either in homozygous or compound heterozygous form, responded to the treatment in vitro. We assessed individual responses to cysteamine plus EGCG in a single-centre, open-label phase-2 trial. The combination treatment decreased sweat chloride from baseline, increased both CFTR protein and function in nasal cells, restored autophagy in such cells, decreased CXCL8 and TNF-α in the sputum, and tended to improve respiratory function. These positive effects were particularly strong in patients carrying Phe508del CFTR mutations in homozygosity or heterozygosity. However, a fraction of patients bearing other CFTR mutations failed to respond to therapy. Importantly, the same patients whose primary nasal brushed cells did not respond to cysteamine plus EGCG in vitro also exhibited deficient therapeutic responses in vivo. Altogether, these results suggest that the combination treatment of cysteamine plus EGCG acts ‘on-target' because it can only rescue CFTR function when autophagy is functional (in mice) and improves CFTR function when a rescuable protein is expressed (in mice and men). These results should spur the further clinical development of the combination treatment. PMID:27035618
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Yeast Genes Controlling Responses to Topogenic Signals in a Model Transmembrane Protein
Tipper, Donald J.; Harley, Carol A
2002-01-01
Yeast protein insertion orientation (PIO) mutants were isolated by selecting for growth on sucrose in cells in which the only source of invertase is a C-terminal fusion to a transmembrane protein. Only the fraction with an exocellular C terminus can be processed to secreted invertase and this fraction is constrained to 2–3% by a strong charge difference signal. Identified pio mutants increased this to 9–12%. PIO1 is SPF1, encoding a P-type ATPase located in the endoplasmic reticulum (ER) or Golgi. spf1-null mutants are modestly sensitive to EGTA. Sensitivity is considerably greater in an spf1 pmr1 double mutant, although PIO is not further disturbed. Pmr1p is the Golgi Ca2+ ATPase and Spf1p may be the equivalent ER pump. PIO2 is STE24, a metalloprotease anchored in the ER membrane. Like Spf1p, Ste24p is expressed in all yeast cell types and belongs to a highly conserved protein family. The effects of ste24- and spf1-null mutations on invertase secretion are additive, cell generation time is increased 60%, and cells become sensitive to cold and to heat shock. Ste24p and Rce1p cleave the C-AAX bond of farnesylated CAAX box proteins. The closest paralog of SPF1 is YOR291w. Neither rce1-null nor yor291w-null mutations affected PIO or the phenotype of spf1- or ste24-null mutants. Mutations in PIO3 (unidentified) cause a weaker Pio phenotype, enhanced by a null mutation in BMH1, one of two yeast 14-3-3 proteins. PMID:11950929
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Maue, Robert A; Burgess, Robert W; Wang, Bing; Wooley, Christine M; Seburn, Kevin L; Vanier, Marie T; Rogers, Maximillian A; Chang, Catherine C; Chang, Ta-Yuan; Harris, Brent T; Graber, David J; Penatti, Carlos A A; Porter, Donna M; Szwergold, Benjamin S; Henderson, Leslie P; Totenhagen, John W; Trouard, Theodore P; Borbon, Ivan A; Erickson, Robert P
2012-02-15
We have identified a point mutation in Npc1 that creates a novel mouse model (Npc1(nmf164)) of Niemann-Pick type C1 (NPC) disease: a single nucleotide change (A to G at cDNA bp 3163) that results in an aspartate to glycine change at position 1005 (D1005G). This change is in the cysteine-rich luminal loop of the NPC1 protein and is highly similar to commonly occurring human mutations. Genetic and molecular biological analyses, including sequencing the Npc1(spm) allele and identifying a truncating mutation, confirm that the mutation in Npc1(nmf164) mice is distinct from those in other existing mouse models of NPC disease (Npc1(nih), Npc1(spm)). Analyses of lifespan, body and spleen weight, gait and other motor activities, as well as acoustic startle responses all reveal a more slowly developing phenotype in Npc1(nmf164) mutant mice than in mice with the null mutations (Npc1(nih), Npc1(spm)). Although Npc1 mRNA levels appear relatively normal, Npc1(nmf164) brain and liver display dramatic reductions in Npc1 protein, as well as abnormal cholesterol metabolism and altered glycolipid expression. Furthermore, histological analyses of liver, spleen, hippocampus, cortex and cerebellum reveal abnormal cholesterol accumulation, glial activation and Purkinje cell loss at a slower rate than in the Npc1(nih) mouse model. Magnetic resonance imaging studies also reveal significantly less demyelination/dysmyelination than in the null alleles. Thus, although prior mouse models may correspond to the severe infantile onset forms of NPC disease, Npc1(nmf164) mice offer many advantages as a model for the late-onset, more slowly progressing forms of NPC disease that comprise the large majority of human cases.
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Maue, Robert A.; Burgess, Robert W.; Wang, Bing; Wooley, Christine M.; Seburn, Kevin L.; Vanier, Marie T.; Rogers, Maximillian A.; Chang, Catherine C.; Chang, Ta-Yuan; Harris, Brent T.; Graber, David J.; Penatti, Carlos A.A.; Porter, Donna M.; Szwergold, Benjamin S.; Henderson, Leslie P.; Totenhagen, John W.; Trouard, Theodore P.; Borbon, Ivan A.; Erickson, Robert P.
2012-01-01
We have identified a point mutation in Npc1 that creates a novel mouse model (Npc1nmf164) of Niemann–Pick type C1 (NPC) disease: a single nucleotide change (A to G at cDNA bp 3163) that results in an aspartate to glycine change at position 1005 (D1005G). This change is in the cysteine-rich luminal loop of the NPC1 protein and is highly similar to commonly occurring human mutations. Genetic and molecular biological analyses, including sequencing the Npc1spm allele and identifying a truncating mutation, confirm that the mutation in Npc1nmf164 mice is distinct from those in other existing mouse models of NPC disease (Npc1nih, Npc1spm). Analyses of lifespan, body and spleen weight, gait and other motor activities, as well as acoustic startle responses all reveal a more slowly developing phenotype in Npc1nmf164 mutant mice than in mice with the null mutations (Npc1nih, Npc1spm). Although Npc1 mRNA levels appear relatively normal, Npc1nmf164 brain and liver display dramatic reductions in Npc1 protein, as well as abnormal cholesterol metabolism and altered glycolipid expression. Furthermore, histological analyses of liver, spleen, hippocampus, cortex and cerebellum reveal abnormal cholesterol accumulation, glial activation and Purkinje cell loss at a slower rate than in the Npc1nih mouse model. Magnetic resonance imaging studies also reveal significantly less demyelination/dysmyelination than in the null alleles. Thus, although prior mouse models may correspond to the severe infantile onset forms of NPC disease, Npc1nmf164 mice offer many advantages as a model for the late-onset, more slowly progressing forms of NPC disease that comprise the large majority of human cases. PMID:22048958
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Chang, Weizhong; Barnes, Aileen M; Cabral, Wayne A; Bodurtha, Joann N; Marini, Joan C
2010-01-15
Null mutations in cartilage-associated protein (CRTAP) and prolyl 3-hydroxylase 1 (P3H1/LEPRE1) cause types VII and VIII OI, respectively, two novel recessive forms of osteogenesis imperfecta (OI) with severe to lethal bone dysplasia and overmodification of the type I collagen helical region. CRTAP and P3H1 form a complex with cyclophilin B (CyPB) in the endoplasmic reticulum (ER) which 3-hydroxylates the Pro986 residue of alpha1(I) and alpha1(II) collagen chains. We investigated the interaction of complex components in fibroblasts from types VII and VIII OI patients. Both CRTAP and P3H1 are absent or reduced on western blots and by immunofluorescence microscopy in cells containing null mutations in either gene. Levels of LEPRE1 or CRTAP transcripts, however, are normal in CRTAP- or LEPRE1-null cells, respectively. Stable transfection of a CRTAP or LEPRE1 expression construct into cells with null mutations for the transfected cDNA restored both CRTAP and P3H1 protein levels. Normalization of collagen helical modification in transfected CRTAP-null cells demonstrated that the restored proteins functioned effectively as a complex. These data indicate that CRTAP and P3H1 are mutually stabilized in the collagen prolyl 3-hydroxylation complex. CyPB levels were unaffected by mutations in either CRTAP or LEPRE1. Proteasomal inhibitors partially rescue P3H1 protein in CRTAP-null cells. In LEPRE1-null cells, secretion of CRTAP is increased compared with control cells and accounts for 15-20% of the decreased CRTAP detected in cells. Thus, mutual stabilization of P3H1 and CRTAP in the ER collagen modification complex is an underlying mechanism for the overlapping phenotype of types VII and VIII OI.
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Null missense ABCR (ABCA4) mutations in a family with stargardt disease and retinitis pigmentosa.
Shroyer, N F; Lewis, R A; Yatsenko, A N; Lupski, J R
2001-11-01
To determine the type of ABCR mutations that segregate in a family that manifests both Stargardt disease (STGD) and retinitis pigmentosa (RP), and the functional consequences of the underlying mutations. Direct sequencing of all 50 exons and flanking intronic regions of ABCR was performed for the STGD- and RP-affected relatives. RNA hybridization, Western blot analysis, and azido-adenosine triphosphate (ATP) labeling was used to determine the effect of disease-associated ABCR mutations in an in vitro assay system. Compound heterozygous missense mutations were identified in patients with STGD and RP. STGD-affected individual AR682-03 was compound heterozygous for the mutation 2588G-->C and a complex allele, [W1408R; R1640W]. RP-affected individuals AR682-04 and-05 were compound heterozygous for the complex allele [W1408R; R1640W] and the missense mutation V767D. Functional analysis of the mutation V767D by Western blot and ATP binding revealed a severe reduction in protein expression. In vitro analysis of ABCR protein with the mutations W1408R and R1640W showed a moderate effect of these individual mutations on expression and ATP-binding; the complex allele [W1408R; R1640W] caused a severe reduction in protein expression. These data reveal that missense ABCR mutations may be associated with RP. Functional analysis reveals that the RP-associated missense ABCR mutations are likely to be functionally null. These studies of the complex allele W1408R; R1640W suggest a synergistic effect of the individual mutations. These data are congruent with a model in which RP is associated with homozygous null mutations and with the notion that severity of retinal disease is inversely related to residual ABCR activity.
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NASA Technical Reports Server (NTRS)
Fritzsch, Bernd
2003-01-01
The molecular and cellular origin of the primary neurons of the inner ear, the vestibular and spiral neurons, is reviewed including how they connect to the specific sensory epithelia and what the molecular nature of their survival is. Primary neurons of the ear depend on a single basic Helix-Loop-Helix (bHLH) protein for their formation, neurogenin 1 (ngn1). An immediate downstream gene is the bHLH gene neuronal differentiation (NeuroD). Targeted null mutations of ngn1 results in absence of primary neuron formation; targeted null mutation of NeuroD results in loss of almost all spiral and many vestibular neurons. NeuroD and a later expressed gene, Brn3a, play a role in pathfinding to and within sensory epithelia. The molecular nature of this pathfinding property is unknown. Reduction of hair cells in ngn1 null mutations suggests a clonal relationship with primary neurons. This relationship may play some role in specifying the identity of hair cells and the primary neurons that connect with them. Primary neuron neurites growth to sensory epithelia is initially independent of trophic factors released from developing sensory epithelia, but becomes rapidly dependent on those factors. Null mutations of specific neurotrophic factors lose distinct primary neuron populations which undergo rapid embryonic cell death.
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A diffusion model for the fate of tandem gene duplicates in diploids.
O'Hely, Martin
2007-06-01
Suppose one chromosome in one member of a population somehow acquires a duplicate copy of the gene, fully linked to the original gene's locus. Preservation is the event that eventually every chromosome in the population is a descendant of the one which initially carried the duplicate. For a haploid population in which the absence of all copies of the gene is lethal, the probability of preservation has recently been estimated via a diffusion approximation. That approximation is shown to carry over to the case of diploids and arbitrary strong selection against the absence of the gene. The techniques used lead to some new results. In the large population limit, it is shown that the relative probability that descendants of a small number of individuals carrying multiple copies of the gene fix in the population is proportional to the number of copies carried. The probability of preservation is approximated when chromosomes carrying two copies of the gene are subject to additional, fully non-functionalizing mutations, thereby modelling either an additional cost of replicating a longer genome, or a partial duplication of the gene. In the latter case the preservation probability depends only on the mutation rate to null for the duplicated portion of the gene.
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Replaying evolutionary transitions from the dental fossil record
Harjunmaa, Enni; Seidel, Kerstin; Häkkinen, Teemu; Renvoisé, Elodie; Corfe, Ian J.; Kallonen, Aki; Zhang, Zhao-Qun; Evans, Alistair R.; Mikkola, Marja L.; Salazar-Ciudad, Isaac; Klein, Ophir D.; Jernvall, Jukka
2014-01-01
The evolutionary relationships of extinct species are ascertained primarily through the analysis of morphological characters. Character inter-dependencies can have a substantial effect on evolutionary interpretations, but the developmental underpinnings of character inter-dependence remain obscure because experiments frequently do not provide detailed resolution of morphological characters. Here we show experimentally and computationally how gradual modification of development differentially affects characters in the mouse dentition. We found that intermediate phenotypes could be produced by gradually adding ectodysplasin A (EDA) protein in culture to tooth explants carrying a null mutation in the tooth-patterning gene Eda. By identifying development-based character interdependencies, we show how to predict morphological patterns of teeth among mammalian species. Finally, in vivo inhibition of sonic hedgehog signalling in Eda null teeth enabled us to reproduce characters deep in the rodent ancestry. Taken together, evolutionarily informative transitions can be experimentally reproduced, thereby providing development-based expectations for character state transitions used in evolutionary studies. PMID:25079326
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Homozygous null mutations in ZMPSTE24 in restrictive dermopathy: evidence of genetic heterogeneity.
Ahmad, Z; Phadke, S R; Arch, E; Glass, J; Agarwal, A K; Garg, A
2012-02-01
Restrictive dermopathy (RD) results in stillbirth or early neonatal death. RD is characterized by prematurity, intrauterine growth retardation, fixed facial expression, micrognathia, mouth in the 'o' position, rigid and tense skin with erosions and denudations and multiple joint contractures. Nearly all 25 previously reported neonates with RD had homozygous or compound heterozygous null mutations in the ZMPSTE24 gene. Here, we report three new cases of RD; all died within 3 weeks of birth. One of them had a previously reported homozygous c.1085dupT (p.Leu362PhefsX19) mutation, the second case had a novel homozygous c.1020G>A (p.Trp340X) null mutation in ZMPSTE24, but the third case, a stillborn with features of RD except for the presence of tapering rather than rounded, bulbous digits, harbored no disease-causing mutations in LMNA or ZMPSTE24. In the newborn with a novel ZMPSTE24 mutation, unique features included butterfly-shaped thoracic 5 vertebra and the bulbous appearance of the distal clavicles. Skin biopsies from both the stillborn fetus and the newborn with c.1020G>A ZMPSTE24 mutation showed absence of elastic fibers throughout the dermis. This report provides evidence of genetic heterogeneity among RD and concludes that there may be an additional locus for RD which remains to be identified. © 2010 John Wiley & Sons A/S.
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Role of Plasmodium vivax Duffy-binding protein 1 in invasion of Duffy-null Africans
Gunalan, Karthigayan; Lo, Eugenia; Hostetler, Jessica B.; Yewhalaw, Delenasaw; Mu, Jianbing; Neafsey, Daniel E.; Yan, Guiyun; Miller, Louis H.
2016-01-01
The ability of the malaria parasite Plasmodium vivax to invade erythrocytes is dependent on the expression of the Duffy blood group antigen on erythrocytes. Consequently, Africans who are null for the Duffy antigen are not susceptible to P. vivax infections. Recently, P. vivax infections in Duffy-null Africans have been documented, raising the possibility that P. vivax, a virulent pathogen in other parts of the world, may expand malarial disease in Africa. P. vivax binds the Duffy blood group antigen through its Duffy-binding protein 1 (DBP1). To determine if mutations in DBP1 resulted in the ability of P. vivax to bind Duffy-null erythrocytes, we analyzed P. vivax parasites obtained from two Duffy-null individuals living in Ethiopia where Duffy-null and -positive Africans live side-by-side. We determined that, although the DBP1s from these parasites contained unique sequences, they failed to bind Duffy-null erythrocytes, indicating that mutations in DBP1 did not account for the ability of P. vivax to infect Duffy-null Africans. However, an unusual DNA expansion of DBP1 (three and eight copies) in the two Duffy-null P. vivax infections suggests that an expansion of DBP1 may have been selected to allow low-affinity binding to another receptor on Duffy-null erythrocytes. Indeed, we show that Salvador (Sal) I P. vivax infects Squirrel monkeys independently of DBP1 binding to Squirrel monkey erythrocytes. We conclude that P. vivax Sal I and perhaps P. vivax in Duffy-null patients may have adapted to use new ligand–receptor pairs for invasion. PMID:27190089
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Greenbury, Sam F.; Schaper, Steffen; Ahnert, Sebastian E.; Louis, Ard A.
2016-01-01
Mutational neighbourhoods in genotype-phenotype (GP) maps are widely believed to be more likely to share characteristics than expected from random chance. Such genetic correlations should strongly influence evolutionary dynamics. We explore and quantify these intuitions by comparing three GP maps—a model for RNA secondary structure, the HP model for protein tertiary structure, and the Polyomino model for protein quaternary structure—to a simple random null model that maintains the number of genotypes mapping to each phenotype, but assigns genotypes randomly. The mutational neighbourhood of a genotype in these GP maps is much more likely to contain genotypes mapping to the same phenotype than in the random null model. Such neutral correlations can be quantified by the robustness to mutations, which can be many orders of magnitude larger than that of the null model, and crucially, above the critical threshold for the formation of large neutral networks of mutationally connected genotypes which enhance the capacity for the exploration of phenotypic novelty. Thus neutral correlations increase evolvability. We also study non-neutral correlations: Compared to the null model, i) If a particular (non-neutral) phenotype is found once in the 1-mutation neighbourhood of a genotype, then the chance of finding that phenotype multiple times in this neighbourhood is larger than expected; ii) If two genotypes are connected by a single neutral mutation, then their respective non-neutral 1-mutation neighbourhoods are more likely to be similar; iii) If a genotype maps to a folding or self-assembling phenotype, then its non-neutral neighbours are less likely to be a potentially deleterious non-folding or non-assembling phenotype. Non-neutral correlations of type i) and ii) reduce the rate at which new phenotypes can be found by neutral exploration, and so may diminish evolvability, while non-neutral correlations of type iii) may instead facilitate evolutionary exploration and so increase evolvability. PMID:26937652
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Merwe, Celia van der, E-mail: celiavdm@sun.ac.za; Loos, Ben; Swart, Chrisna
Highlights: • Mitochondrial dysfunction observed in patients with parkin-null mutations. • Mitochondrial ATP levels were decreased. • Electron-dense vacuoles were observed in the patients. • Mitochondria from muscle biopsies appeared within normal limits. • One patient did not show these defects possibly due to compensatory mechanisms. - Abstract: Parkinson’s disease (PD), defined as a neurodegenerative disorder, is characterized by the loss of dopaminergic neurons in the substantia nigra in the midbrain. Loss-of-function mutations in the parkin gene are a major cause of autosomal recessive, early-onset PD. Parkin has been implicated in the maintenance of healthy mitochondria, although previous studies showmore » conflicting findings regarding mitochondrial abnormalities in fibroblasts from patients harboring parkin-null mutations. The aim of the present study was to determine whether South African PD patients with parkin mutations exhibit evidence for mitochondrial dysfunction. Fibroblasts were cultured from skin biopsies obtained from three patients with homozygous parkin-null mutations, two heterozygous mutation carriers and two wild-type controls. Muscle biopsies were obtained from two of the patients. The muscle fibers showed subtle abnormalities such as slightly swollen mitochondria in focal areas of the fibers and some folding of the sarcolemma. Although no differences in the degree of mitochondrial network branching were found in the fibroblasts, ultrastructural abnormalities were observed including the presence of electron-dense vacuoles. Moreover, decreased ATP levels which are consistent with mitochondrial dysfunction were observed in the patients’ fibroblasts compared to controls. Remarkably, these defects did not manifest in one patient, which may be due to possible compensatory mechanisms. These results suggest that parkin-null patients exhibit features of mitochondrial dysfunction. Involvement of mitochondria as a key role player in PD pathogenesis will have important implications for the design of new and more effective therapies.« less
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The OmpL porin does not modulate redox potential in the periplasmic space of Escherichia coli.
Sardesai, Abhijit A; Genevaux, Pierre; Schwager, Françoise; Ang, Debbie; Georgopoulos, Costa
2003-04-01
The Escherichia coli DsbA protein is the major oxidative catalyst in the periplasm. Dartigalongue et al. (EMBO J., 19, 5980-5988, 2000) reported that null mutations in the ompL gene of E.coli fully suppress all phenotypes associated with dsbA mutants, i.e. sensitivity to the reducing agent dithiothreitol (DTT) and the antibiotic benzylpenicillin, lack of motility, reduced alkaline phosphatase activity and mucoidy. They showed that OmpL is a porin and hypothesized that ompL null mutations exert their suppressive effect by preventing efflux of a putative oxidizing-reducing compound into the medium. We have repeated these experiments using two different ompL null alleles in at least three different E.coli K-12 genetic backgrounds and have failed to reproduce any of the ompL suppressive effects noted above. Also, we show that, contrary to earlier results, ompL null mutations alone do not result in partial DTT sensitivity or partial motility, nor do they appreciably affect bacterial growth rates or block propagation of the male-specific bacteriophage M13. Thus, our findings clearly demonstrate that ompL plays no perceptible role in modulating redox potential in the periplasm of E.coli.
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A method distinguishing expressed vs. null mutations of the Col1A1 gene in osteogenesis imperfecta
DOE Office of Scientific and Technical Information (OSTI.GOV)
Redford-Badwal, D.A.; Stover, M.L.; McKinstry, M.
Osteogenesis imperfecta (OI) is a heterogeneous group of heritable disorders of bone characterized by increased susceptibility to fracture. Most of the causative mutations were identified in patients with the lethal form of the disease. Attention is now shifting to the milder forms of OI where glycine substitutions and null producing mutations have been found. Single amino acid substitutions can be identified by RT/PCR of total cellular RNA, but this approach does not work well for null mutations since the defective transcript does not accumulate in the cytoplasm. We have altered our RNA extraction method to separate RNA from the nuclearmore » and cytoplasmic compartments of cultured fibroblasts. Standard methods of mutation identification (RT/PCR followed by SSCP) is applied to each RNA fraction. DNA from an abnormal band on the SSCP gel is eluted and amplified by PCR for cloning and sequencing. Using this approach we have identified an Asp to Asn change in exon 50 (type II OI) and a Gly to Arg in exon 11 (type I OI) of the COL1A1 gene. These changes were found in both nuclear and cytoplasmic compartments. These putative mutations are currently being confirmed by protein studies. In contrast, three patients with mild OI associated with reduced {proportional_to}(I)mRNA, had distinguishing SSCP bands present in the nuclear but not the cytoplasmic compartment. In one case a frame shift mutation was observed, while the other two revealed polymorphisms. The compartmentalization of the mutant allele has directed us to look elsewhere in the transcript for the causative mutation. This approach to mutation identification is capable of distinguishing these fundamentally different types of mutations and allows for preferential cloning and sequencing of the abnormal allele.« less
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del Carmen Burón-Barral, Maria; Gosink, Khoosheh K.; Parkinson, John S.
2006-01-01
The Escherichia coli Aer protein contains an N-terminal PAS domain that binds flavin adenine dinucleotide (FAD), senses aerotactic stimuli, and communicates with the output signaling domain. To explore the roles of the intervening F1 and HAMP segments in Aer signaling, we isolated plasmid-borne aerotaxis-defective mutations in a host strain lacking all chemoreceptors of the methyl-accepting chemotaxis protein (MCP) family. Under these conditions, Aer alone established the cell's run/tumble swimming pattern and modulated that behavior in response to oxygen gradients. We found two classes of Aer mutants: null and clockwise (CW) biased. Most mutant proteins exhibited the null phenotype: failure to elicit CW flagellar rotation, no aerosensing behavior in MCP-containing hosts, and no apparent FAD-binding ability. However, null mutants had low Aer expression levels caused by rapid degradation of apparently nonnative subunits. Their functional defects probably reflect the absence of a protein product. In contrast, CW-biased mutant proteins exhibited normal expression levels, wild-type FAD binding, and robust aerosensing behavior in MCP-containing hosts. The CW lesions evidently shift unstimulated Aer output to the CW signaling state but do not block the Aer input-output pathway. The distribution and properties of null and CW-biased mutations suggest that the Aer PAS domain may engage in two different interactions with HAMP and the HAMP-proximal signaling domain: one needed for Aer maturation and another for promoting CW output from the Aer signaling domain. Most aerotaxis-defective null mutations in these regions seemed to affect maturation only, indicating that these two interactions involve structurally distinct determinants. PMID:16672601
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Szabo, R; Samson, A L; Lawrence, D A; Medcalf, R L; Bugge, T H
2016-08-01
Essentials C57BL/6J-tissue plasminogen activator (tPA)-deficient mice are widely used to study tPA function. Congenic C57BL/6J-tPA-deficient mice harbor large 129-derived chromosomal segments. The 129-derived chromosomal segments contain gene mutations that may confound data interpretation. Passenger mutation-free isogenic tPA-deficient mice were generated for study of tPA function. Background The ability to generate defined null mutations in mice revolutionized the analysis of gene function in mammals. However, gene-deficient mice generated by using 129-derived embryonic stem cells may carry large segments of 129 DNA, even when extensively backcrossed to reference strains, such as C57BL/6J, and this may confound interpretation of experiments performed in these mice. Tissue plasminogen activator (tPA), encoded by the PLAT gene, is a fibrinolytic serine protease that is widely expressed in the brain. A number of neurological abnormalities have been reported in tPA-deficient mice. Objectives To study genetic contamination of tPA-deficient mice. Materials and methods Whole genome expression array analysis, RNAseq expression profiling, low- and high-density single nucleotide polymorphism (SNP) analysis, bioinformatics and genome editing were used to analyze gene expression in tPA-deficient mouse brains. Results and conclusions Genes differentially expressed in the brain of Plat(-/-) mice from two independent colonies highly backcrossed onto the C57BL/6J strain clustered near Plat on chromosome 8. SNP analysis attributed this anomaly to about 20 Mbp of DNA flanking Plat being of 129 origin in both strains. Bioinformatic analysis of these 129-derived chromosomal segments identified a significant number of mutations in genes co-segregating with the targeted Plat allele, including several potential null mutations. Using zinc finger nuclease technology, we generated novel 'passenger mutation'-free isogenic C57BL/6J-Plat(-/-) and FVB/NJ-Plat(-/-) mouse strains by introducing an 11 bp deletion into the exon encoding the signal peptide. These novel mouse strains will be a useful community resource for further exploration of tPA function in physiological and pathological processes. © 2016 International Society on Thrombosis and Haemostasis.
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The dev Operon Regulates the Timing of Sporulation during Myxococcus xanthus Development.
Rajagopalan, Ramya; Kroos, Lee
2017-05-15
Myxococcus xanthus undergoes multicellular development when starved. Thousands of rod-shaped cells coordinate their movements and aggregate into mounds in which cells differentiate into spores. Mutations in the dev operon impair development. The dev operon encompasses a clustered regularly interspaced short palindromic repeat-associated (CRISPR-Cas) system. Null mutations in devI , a small gene at the beginning of the dev operon, suppress the developmental defects caused by null mutations in the downstream devR and devS genes but failed to suppress defects caused by a small in-frame deletion in devT We provide evidence that the original mutant has a second-site mutation. We show that devT null mutants exhibit developmental defects indistinguishable from devR and devS null mutants, and a null mutation in devI suppresses the defects of a devT null mutation. The similarity of DevTRS proteins to components of the CRISPR-associated complex for antiviral defense (Cascade), together with our molecular characterization of dev mutants, support a model in which DevTRS form a Cascade-like subcomplex that negatively autoregulates dev transcript accumulation and prevents DevI overproduction that would strongly inhibit sporulation. Our results also suggest that DevI transiently inhibits sporulation when regulated normally. The mechanism of transient inhibition may involve MrpC, a key transcription factor, whose translation appears to be weakly inhibited by DevI. Finally, our characterization of a devI devS mutant indicates that very little exo transcript is required for sporulation, which is surprising since Exo proteins help form the polysaccharide spore coat. IMPORTANCE CRISPR-Cas systems typically function as adaptive immune systems in bacteria. The dev CRISPR-Cas system of M. xanthus has been proposed to prevent bacteriophage infection during development, but how dev controls sporulation has been elusive. Recent evidence supported a model in which DevR and DevS prevent overproduction of DevI, a predicted 40-residue inhibitor of sporulation. We provide genetic evidence that DevT functions together with DevR and DevS to prevent DevI overproduction. We also show that spores form about 6 h earlier in mutants lacking devI than in the wild type. Only a minority of natural isolates appear to have a functional dev promoter and devI , suggesting that a functional dev CRISPR-Cas system evolved recently in niches where delayed sporulation and/or protection from bacteriophage infection proved advantageous. Copyright © 2017 American Society for Microbiology.
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The dev Operon Regulates the Timing of Sporulation during Myxococcus xanthus Development
Rajagopalan, Ramya
2017-01-01
ABSTRACT Myxococcus xanthus undergoes multicellular development when starved. Thousands of rod-shaped cells coordinate their movements and aggregate into mounds in which cells differentiate into spores. Mutations in the dev operon impair development. The dev operon encompasses a clustered regularly interspaced short palindromic repeat-associated (CRISPR-Cas) system. Null mutations in devI, a small gene at the beginning of the dev operon, suppress the developmental defects caused by null mutations in the downstream devR and devS genes but failed to suppress defects caused by a small in-frame deletion in devT. We provide evidence that the original mutant has a second-site mutation. We show that devT null mutants exhibit developmental defects indistinguishable from devR and devS null mutants, and a null mutation in devI suppresses the defects of a devT null mutation. The similarity of DevTRS proteins to components of the CRISPR-associated complex for antiviral defense (Cascade), together with our molecular characterization of dev mutants, support a model in which DevTRS form a Cascade-like subcomplex that negatively autoregulates dev transcript accumulation and prevents DevI overproduction that would strongly inhibit sporulation. Our results also suggest that DevI transiently inhibits sporulation when regulated normally. The mechanism of transient inhibition may involve MrpC, a key transcription factor, whose translation appears to be weakly inhibited by DevI. Finally, our characterization of a devI devS mutant indicates that very little exo transcript is required for sporulation, which is surprising since Exo proteins help form the polysaccharide spore coat. IMPORTANCE CRISPR-Cas systems typically function as adaptive immune systems in bacteria. The dev CRISPR-Cas system of M. xanthus has been proposed to prevent bacteriophage infection during development, but how dev controls sporulation has been elusive. Recent evidence supported a model in which DevR and DevS prevent overproduction of DevI, a predicted 40-residue inhibitor of sporulation. We provide genetic evidence that DevT functions together with DevR and DevS to prevent DevI overproduction. We also show that spores form about 6 h earlier in mutants lacking devI than in the wild type. Only a minority of natural isolates appear to have a functional dev promoter and devI, suggesting that a functional dev CRISPR-Cas system evolved recently in niches where delayed sporulation and/or protection from bacteriophage infection proved advantageous. PMID:28264995
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Lopez, G H; Morrison, J; Condon, J A; Wilson, B; Martin, J R; Liew, Y-W; Flower, R L; Hyland, C A
2015-10-01
Duffy blood group phenotypes can be predicted by genotyping for single nucleotide polymorphisms (SNPs) responsible for the Fy(a) /Fy(b) polymorphism, for weak Fy(b) antigen, and for the red cell null Fy(a-b-) phenotype. This study correlates Duffy phenotype predictions with serotyping to assess the most reliable procedure for typing. Samples, n = 155 (135 donors and 20 patients), were genotyped by high-resolution melt PCR and by microarray. Samples were in three serology groups: 1) Duffy patterns expected n = 79, 2) weak and equivocal Fy(b) patterns n = 29 and 3) Fy(a-b-) n = 47 (one with anti-Fy3 antibody). Discrepancies were observed for five samples. For two, SNP genotyping predicted weak Fy(b) expression discrepant with Fy(b-) (Group 1 and 3). For three, SNP genotyping predicted Fy(a) , discrepant with Fy(a-b-) (Group 3). DNA sequencing identified silencing mutations in these FY*A alleles. One was a novel FY*A 719delG. One, the sample with the anti-Fy3, was homozygous for a 14-bp deletion (FY*01N.02); a true null. Both the high-resolution melting analysis and SNP microarray assays were concordant and showed genotyping, as well as phenotyping, is essential to ensure 100% accuracy for Duffy blood group assignments. Sequencing is important to resolve phenotype/genotype conflicts which here identified alleles, one novel, that carry silencing mutations. The risk of alloimmunisation may be dependent on this zygosity status. © 2015 International Society of Blood Transfusion.
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Bergeret, Evelyne; Pignot-Paintrand, Isabelle; Guichard, Annabel; Raymond, Karine; Fauvarque, Marie-Odile; Cazemajor, Michel; Griffin-Shea, Ruth
2001-01-01
Our analysis of rotund (rn) null mutations in Drosophila melanogaster revealed that deletion of the rn locus affects both spermatid and retinal differentiation. In the male reproductive system, the absence of RnRacGAP induced small testes, empty seminal vesicles, short testicular cysts, reduced amounts of interspermatid membrane, the absence of individualization complexes, and incomplete mitochondrial condensation. Flagellar growth continued within the short rn null cysts to produce large bulbous terminations of intertwined mature flagella. Organization of the retina was also severely perturbed as evidenced by grossly misshapen ommatidia containing reduced numbers of photoreceptor and pigment cells. These morphological phenotypes were rescued by genomic rnRacGAP transgenes, demonstrating that RnRacGAP function is critical to spermatid and retinal differentiation. The testicular phenotypes were suppressed by heterozygous hypomorphic mutations in the Dras1 and drk genes, indicating cross talk between RacGAP-regulated signaling and that of the Ras pathway. The observed genetic interactions are consistent with a model in which Rac signaling is activated by Ras and negatively regulated by RnRacGAP during spermatid differentiation. RnRacGAP and Ras cross talk also operated during retinal differentiation; however, while the heterozygous hypomorphic drk mutation continued to act as a suppressor of the rn null mutation, the heterozygous hypomorphic Dras1 mutation induced novel retinal phenotypes. PMID:11509670
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USDA-ARS?s Scientific Manuscript database
SPS (Sucrose phosphate synthase) isoforms from dicots cluster into families A, B and C. In this study, we investigated the individual effect of null mutations of each of the four SPS genes in Arabidopsis (spsa1, spsa2, spsb and spsc) on photosynthesis and carbon partitioning. Null mutants spsa1 and ...
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A second component of the SltA-dependent cation tolerance pathway in Aspergillus nidulans.
Mellado, Laura; Calcagno-Pizarelli, Ana Maria; Lockington, Robin A; Cortese, Marc S; Kelly, Joan M; Arst, Herbert N; Espeso, Eduardo A
2015-09-01
The transcriptional response to alkali metal cation stress is mediated by the zinc finger transcription factor SltA in Aspergillus nidulans and probably in other fungi of the pezizomycotina subphylum. A second component of this pathway has been identified and characterized. SltB is a 1272 amino acid protein with at least two putative functional domains, a pseudo-kinase and a serine-endoprotease, involved in signaling to the transcription factor SltA. Absence of SltB activity results in nearly identical phenotypes to those observed for a null sltA mutant. Hypersensitivity to a variety of monovalent and divalent cations, and to medium alkalinization are among the phenotypes exhibited by a null sltB mutant. Calcium homeostasis is an exception and this cation improves growth of sltΔ mutants. Moreover, loss of kinase HalA in conjunction with loss-of-function sltA or sltB mutations leads to pronounced calcium auxotrophy. sltA sltB double null mutants display a cation stress sensitive phenotype indistinguishable from that of single slt mutants showing the close functional relationship between these two proteins. This functional relationship is reinforced by the fact that numerous mutations in both slt loci can be isolated as suppressors of poor colonial growth resulting from certain null vps (vacuolar protein sorting) mutations. In addition to allowing identification of sltB, our sltB missense mutations enabled prediction of functional regions in the SltB protein. Although the relationship between the Slt and Vps pathways remains enigmatic, absence of SltB, like that of SltA, leads to vacuolar hypertrophy. Importantly, the phenotypes of selected sltA and sltB mutations demonstrate that suppression of null vps mutations is not dependent on the inability to tolerate cation stress. Thus a specific role for both SltA and SltB in the VPS pathway seems likely. Finally, it is noteworthy that SltA and SltB have a similar, limited phylogenetic distribution, being restricted to the pezizomycotina subphylum. The relevance of the Slt regulatory pathway to cell structure, intracellular trafficking and cation homeostasis and its restricted phylogenetic distribution makes this pathway of general interest for future investigation and as a source of targets for antifungal drugs. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
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Pollin, Toni I; Damcott, Coleen M; Shen, Haiqing; Ott, Sandra H; Shelton, John; Horenstein, Richard B; Post, Wendy; McLenithan, John C; Bielak, Lawrence F; Peyser, Patricia A; Mitchell, Braxton D; Miller, Michael; O'Connell, Jeffrey R; Shuldiner, Alan R
2008-12-12
Apolipoprotein C-III (apoC-III) inhibits triglyceride hydrolysis and has been implicated in coronary artery disease. Through a genome-wide association study, we have found that about 5% of the Lancaster Amish are heterozygous carriers of a null mutation (R19X) in the gene encoding apoC-III (APOC3) and, as a result, express half the amount of apoC-III present in noncarriers. Mutation carriers compared with noncarriers had lower fasting and postprandial serum triglycerides, higher levels of HDL-cholesterol and lower levels of LDL-cholesterol. Subclinical atherosclerosis, as measured by coronary artery calcification, was less common in carriers than noncarriers, which suggests that lifelong deficiency of apoC-III has a cardioprotective effect.
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Mandrile, Giorgia; van Woerden, Christiaan S; Berchialla, Paola; Beck, Bodo B; Acquaviva Bourdain, Cécile; Hulton, Sally-Anne; Rumsby, Gill
2014-12-01
Primary hyperoxaluria type 1 displays a heterogeneous phenotype, likely to be affected by genetic and non-genetic factors, including timeliness of diagnosis and quality of care. As previous genotype-phenotype studies were hampered by limited patient numbers the European OxalEurope Consortium was constituted. This preliminary retrospective report is based on 526 patients of which 410 have the AGXT genotype defined. We grouped mutations by the predicted effect as null, missense leading to mistargeting (G170R), and other missense, and analyzed their phenotypic correlations. Median age of end-stage renal disease increased from 9.9 for 88 homozygous null patients, 11.5 for 42 heterozygous null/missense, 16.9 for 116 homozygous missense patients, 25.1 for 61 G170R/null patients, 31.2 for 32 G170R/missense patients, and 33.9 years for 71 homozygous G170R patients. The outcome of some recurrent missense mutations (p.I244T, p.F152I, p.M195R, p.D201E, p.S81L, p.R36C) and an unprecedented number of G170R homozygotes is described in detail. Diagnosis is still delayed and actions aimed at increasing awareness of primary hyperoxaluria type 1 are recommended. Thus, in addition to G170R, other causative mutations are associated with later onset of end-stage renal disease. The OxalEurope registry will provide necessary tools for characterizing those genetic and non-genetic factors through a combination of genetic, functional, and biostatistical approaches.
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Ler, Lian Dee; Ghosh, Sujoy; Chai, Xiaoran; Thike, Aye Aye; Heng, Hong Lee; Siew, Ee Yan; Dey, Sucharita; Koh, Liang Kai; Lim, Jing Quan; Lim, Weng Khong; Myint, Swe Swe; Loh, Jia Liang; Ong, Pauline; Sam, Xin Xiu; Huang, Dachuan; Lim, Tony; Tan, Puay Hoon; Nagarajan, Sanjanaa; Cheng, Christopher Wai Sam; Ho, Henry; Ng, Lay Guat; Yuen, John; Lin, Po-Hung; Chuang, Cheng-Keng; Chang, Ying-Hsu; Weng, Wen-Hui; Rozen, Steven G; Tan, Patrick; Creasy, Caretha L; Pang, See-Tong; McCabe, Michael T; Poon, Song Ling; Teh, Bin Tean
2017-02-22
Trithorax-like group complex containing KDM6A acts antagonistically to Polycomb-repressive complex 2 (PRC2) containing EZH2 in maintaining the dynamics of the repression and activation of gene expression through H3K27 methylation. In urothelial bladder carcinoma, KDM6A (a H3K27 demethylase) is frequently mutated, but its functional consequences and therapeutic targetability remain unknown. About 70% of KDM6A mutations resulted in a total loss of expression and a consequent loss of demethylase function in this cancer type. Further transcriptome analysis found multiple deregulated pathways, especially PRC2/EZH2, in KDM6A -mutated urothelial bladder carcinoma. Chromatin immunoprecipitation sequencing analysis revealed enrichment of H3K27me3 at specific loci in KDM6A -null cells, including PRC2/EZH2 and their downstream targets. Consequently, we targeted EZH2 (an H3K27 methylase) and demonstrated that KDM6A -null urothelial bladder carcinoma cell lines were sensitive to EZH2 inhibition. Loss- and gain-of-function assays confirmed that cells with loss of KDM6A are vulnerable to EZH2. IGFBP3, a direct KDM6A/EZH2/H3K27me3 target, was up-regulated by EZH2 inhibition and contributed to the observed EZH2-dependent growth suppression in KDM6A -null cell lines. EZH2 inhibition delayed tumor onset in KDM6A -null cells and caused regression of KDM6A -null bladder tumors in both patient-derived and cell line xenograft models. In summary, our study demonstrates that inactivating mutations of KDM6A , which are common in urothelial bladder carcinoma, are potentially targetable by inhibiting EZH2. Copyright © 2017, American Association for the Advancement of Science.
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Phenotypic analysis of separation-of-function alleles of MEI-41, Drosophila ATM/ATR.
Laurençon, Anne; Purdy, Amanda; Sekelsky, Jeff; Hawley, R Scott; Su, Tin Tin
2003-01-01
ATM/ATR kinases act as signal transducers in eukaryotic DNA damage and replication checkpoints. Mutations in ATM/ATR homologs have pleiotropic effects that range from sterility to increased killing by genotoxins in humans, mice, and Drosophila. Here we report the generation of a null allele of mei-41, Drosophila ATM/ATR homolog, and the use of it to document a semidominant effect on a larval mitotic checkpoint and methyl methanesulfonate (MMS) sensitivity. We also tested the role of mei-41 in a recently characterized checkpoint that delays metaphase/anaphase transition after DNA damage in cellular embryos. We then compare five existing mei-41 alleles to the null with respect to known phenotypes (female sterility, cell cycle checkpoints, and MMS resistance). We find that not all phenotypes are affected equally by each allele, i.e., the functions of MEI-41 in ensuring fertility, cell cycle regulation, and resistance to genotoxins are genetically separable. We propose that MEI-41 acts not in a single rigid signal transduction pathway, but in multiple molecular contexts to carry out its many functions. Sequence analysis identified mutations, which, for most alleles, fall in the poorly characterized region outside the kinase domain; this allowed us to tentatively identify additional functional domains of MEI-41 that could be subjected to future structure-function studies of this key molecule. PMID:12807779
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Novel USH2A mutations in Israeli patients with retinitis pigmentosa and Usher syndrome type 2.
Kaiserman, Nadia; Obolensky, Alexey; Banin, Eyal; Sharon, Dror
2007-02-01
To identify USH2A mutations in Israeli patients with autosomal-recessive Usher syndrome type 2 (USH2) and retinitis pigmentosa (RP). Patients from 95 families with RP and 4 with USH2 were clinically evaluated. USH2A exons 2-72 were scanned for mutations using single-strand conformation and sequencing analyses. The frequency of novel missense changes was determined in patients and controls using restriction endonucleases. The analysis revealed 3 USH2A mutations, 2 of which are novel, in 2 families with USH2 and a large family (MOL0051) with both USH2 and RP. Compound heterozygotes for 2 null mutations (Thr80fs and Arg737stop) in MOL0051 suffered from USH2 while compound heterozygotes for 1 of the null mutations and a novel missense mutation (Gly4674Arg) had nonsyndromic RP. Our results support the involvement of USH2A in nonsyndromic RP and we report here of a second, novel, missense mutation in this gene causing autosomal-recessive RP. Possible involvement of USH2A should be considered in the molecular genetic evaluation of patients with autosomal-recessive RP. Understanding the mechanism by which different USH2A mutations cause either USH2 or RP may assist in the development of novel therapeutic approaches.
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Role of a new Rho family member in cell migration and axon guidance in C. elegans.
Zipkin, I D; Kindt, R M; Kenyon, C J
1997-09-05
Rho family GTPases are thought to regulate actin-dependent processes, but their functions in vivo are still poorly understood. We have investigated the function of a new, widely expressed Rho family member in C. elegans by analyzing mutations in the endogenous gene. Activated and null alleles all inhibit cell migration, demonstrating that this protein is required for cell migration in vivo. Only a small subset of the migrations inhibited by activating mutations are inhibited by null mutations, suggesting that considerable functional redundancy exists within this system. Our findings support this conclusion and show that mig-2 functions redundantly with another pathway to regulate nuclear migration. Surprisingly, activated alleles also cause misguided axon growth, suggesting that Rho family GTPases may couple guidance cues to process outgrowth.
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Both XPD alleles contribute to the phenotype of compound heterozygote xeroderma pigmentosum patients
Ueda, Takahiro; Compe, Emmanuel; Catez, Philippe; Kraemer, Kenneth H.
2009-01-01
Mutations in the XPD subunit of the DNA repair/transcription factor TFIIH result in the rare recessive genetic disorder xeroderma pigmentosum (XP). Many XP patients are compound heterozygotes with a “causative” XPD point mutation R683W and different second mutant alleles, considered “null alleles.” However, there is marked clinical heterogeneity (including presence or absence of skin cancers or neurological degeneration) in these XPD/R683W patients, thus suggesting a contribution of the second allele. Here, we report XP patients carrying XPD/R683W and a second XPD allele either XPD/Q452X, /I455del, or /199insPP. We performed a systematic study of the effect of these XPD mutations on several enzymatic functions of TFIIH and found that each mutation exhibited unique biochemical properties. Although all the mutations inhibited the nucleotide excision repair (NER) by disturbing the XPD helicase function, each of them disrupted specific molecular steps during transcription: XPD/Q452X hindered the transactivation process, XPD/I455del disturbed RNA polymerase II phosphorylation, and XPD/199insPP inhibited kinase activity of the cdk7 subunit of TFIIH. The broad range and severity of clinical features in XP patients arise from a broad set of deficiencies in NER and transcription that result from the combination of mutations found on both XPD alleles. PMID:19934020
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Goalpha regulates volatile anesthetic action in Caenorhabditis elegans.
van Swinderen, B; Metz, L B; Shebester, L D; Mendel, J E; Sternberg, P W; Crowder, C M
2001-01-01
To identify genes controlling volatile anesthetic (VA) action, we have screened through existing Caenorhabditis elegans mutants and found that strains with a reduction in Go signaling are VA resistant. Loss-of-function mutants of the gene goa-1, which codes for the alpha-subunit of Go, have EC(50)s for the VA isoflurane of 1.7- to 2.4-fold that of wild type. Strains overexpressing egl-10, which codes for an RGS protein negatively regulating goa-1, are also isoflurane resistant. However, sensitivity to halothane, a structurally distinct VA, is differentially affected by Go pathway mutants. The RGS overexpressing strains, a goa-1 missense mutant found to carry a novel mutation near the GTP-binding domain, and eat-16(rf) mutants, which suppress goa-1(gf) mutations, are all halothane resistant; goa-1(null) mutants have wild-type sensitivities. Double mutant strains carrying mutations in both goa-1 and unc-64, which codes for a neuronal syntaxin previously found to regulate VA sensitivity, show that the syntaxin mutant phenotypes depend in part on goa-1 expression. Pharmacological assays using the cholinesterase inhibitor aldicarb suggest that VAs and GOA-1 similarly downregulate cholinergic neurotransmitter release in C. elegans. Thus, the mechanism of action of VAs in C. elegans is regulated by Goalpha, and presynaptic Goalpha-effectors are candidate VA molecular targets. PMID:11404329
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Tourlakis, Marina E; Zhong, Jian; Gandhi, Rikesh; Zhang, Siyi; Chen, Lingling; Durie, Peter R; Rommens, Johanna M
2012-08-01
Shwachman-Diamond syndrome (SDS) is the second leading cause of hereditary exocrine pancreatic dysfunction. More than 90% of patients with SDS have biallelic loss-of-function mutations in the Shwachman-Bodian Diamond syndrome (SBDS) gene, which encodes a factor involved in ribosome function. We investigated whether mutations in Sbds lead to similar pancreatic defects in mice. Pancreas-specific knock-out mice were generated using a floxed Sbds allele and bred with mice carrying a null or disease-associated missense Sbds allele. Cre recombinase, regulated by the pancreatic transcription factor 1a promoter, was used to disrupt Sbds specifically in the pancreas. Models were assessed for pancreatic dysfunction and growth impairment. Disruption of Sbds in the mouse pancreas was sufficient to recapitulate SDS phenotypes. Pancreata of mice with Sbds mutations had decreased mass, fat infiltration, but general preservation of ductal and endocrine compartments. Pancreatic extracts from mutant mice had defects in formation of the 80S ribosomal complex. The exocrine compartment of mutant mice was hypoplastic and individual acini produced few zymogen granules. The null Sbds allele resulted in an earlier onset of phenotypes as well as endocrine impairment. Mutant mice had reduced serum levels of digestive enzymes and overall growth impairment. We developed a mouse model of SDS with pancreatic phenotypes similar to those of the human disease. This model could be used to investigate organ-specific consequences of Sbds-associated ribosomopathy. Sbds genotypes correlated with phenotypes. Defects developed specifically in the pancreata of mice, reducing growth of mice and production of digestive enzymes. SBDS therefore appears to be required for normal pancreatic development and function. Copyright © 2012 AGA Institute. Published by Elsevier Inc. All rights reserved.
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Minimal Phenotype of Mice Homozygous for a Null Mutation in the Forkhead/Winged Helix Gene, Mf2
Kume, Tsutomu; Deng, Keyu; Hogan, Brigid L. M.
2000-01-01
Mf2 (mesoderm/mesenchyme forkhead 2) encodes a forkhead/winged helix transcription factor expressed in numerous tissues of the mouse embryo, including paraxial mesoderm, somites, branchial arches, vibrissae, developing central nervous system, and developing kidney. We have generated mice homozygous for a null mutation in the Mf2 gene (Mf2lacZ) to examine its role during embryonic development. The lacZ allele also allows monitoring of Mf2 gene expression. Homozygous null mutants are viable and fertile and have no major developmental defects. Some mutants show renal abnormalities, including kidney hypoplasia and hydroureter, but the penetrance of this phenotype is only 40% or lower, depending on the genetic background. These data suggest that Mf2 can play a unique role in kidney development, but there is functional redundancy in this organ and other tissues with other forkhead/winged helix genes. PMID:10648626
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Minimal phenotype of mice homozygous for a null mutation in the forkhead/winged helix gene, Mf2.
Kume, T; Deng, K; Hogan, B L
2000-02-01
Mf2 (mesoderm/mesenchyme forkhead 2) encodes a forkhead/winged helix transcription factor expressed in numerous tissues of the mouse embryo, including paraxial mesoderm, somites, branchial arches, vibrissae, developing central nervous system, and developing kidney. We have generated mice homozygous for a null mutation in the Mf2 gene (Mf2(lacZ)) to examine its role during embryonic development. The lacZ allele also allows monitoring of Mf2 gene expression. Homozygous null mutants are viable and fertile and have no major developmental defects. Some mutants show renal abnormalities, including kidney hypoplasia and hydroureter, but the penetrance of this phenotype is only 40% or lower, depending on the genetic background. These data suggest that Mf2 can play a unique role in kidney development, but there is functional redundancy in this organ and other tissues with other forkhead/winged helix genes.
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Kager, Leo; Bruce, Lesley J; Zeitlhofer, Petra; Flatt, Joanna F; Maia, Tabita M; Ribeiro, M Leticia; Fahrner, Bernhard; Fritsch, Gerhard; Boztug, Kaan; Haas, Oskar A
2017-03-01
We describe the second patient with anionic exchanger 1/band 3 null phenotype (band 3 null VIENNA ), which was caused by a novel nonsense mutation c.1430C>A (p.Ser477X) in exon 12 of SLC4A1. We also update on the previous band 3 null COIMBRA patient, thereby elucidating the physiological implications of total loss of AE1/band 3. Besides transfusion-dependent severe hemolytic anemia and complete distal renal tubular acidosis, dyserythropoiesis was identified in the band 3 null VIENNA patient, suggesting a role for band 3 in erythropoiesis. Moreover, we also, for the first time, report that long-term survival is possible in band 3 null patients. © 2016 Wiley Periodicals, Inc.
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Generation of Esr1-Knockout Rats Using Zinc Finger Nuclease-Mediated Genome Editing
Dhakal, Pramod; Kubota, Kaiyu; Chakraborty, Damayanti; Lei, Tianhua; Larson, Melissa A.; Wolfe, Michael W.; Roby, Katherine F.; Vivian, Jay L.
2014-01-01
Estrogens play pivotal roles in development and function of many organ systems, including the reproductive system. We have generated estrogen receptor 1 (Esr1)-knockout rats using zinc finger nuclease (ZFN) genome targeting. mRNAs encoding ZFNs targeted to exon 3 of Esr1 were microinjected into single-cell rat embryos and transferred to pseudopregnant recipients. Of 17 live births, 5 had biallelic and 1 had monoallelic Esr1 mutations. A founder with monoallelic mutations was backcrossed to a wild-type rat. Offspring possessed only wild-type Esr1 alleles or wild-type alleles and Esr1 alleles containing either 482 bp (Δ482) or 223 bp (Δ223) deletions, indicating mosaicism in the founder. These heterozygous mutants were bred for colony expansion, generation of homozygous mutants, and phenotypic characterization. The Δ482 Esr1 allele yielded altered transcript processing, including the absence of exon 3, aberrant splicing of exon 2 and 4, and a frameshift that generated premature stop codons located immediately after the codon for Thr157. ESR1 protein was not detected in homozygous Δ482 mutant uteri. ESR1 disruption affected sexually dimorphic postnatal growth patterns and serum levels of gonadotropins and sex steroid hormones. Both male and female Esr1-null rats were infertile. Esr1-null males had small testes with distended and dysplastic seminiferous tubules, whereas Esr1-null females possessed large polycystic ovaries, thread-like uteri, and poorly developed mammary glands. In addition, uteri of Esr1-null rats did not effectively respond to 17β-estradiol treatment, further demonstrating that the Δ482 Esr1 mutation created a null allele. This rat model provides a new experimental tool for investigating the pathophysiology of estrogen action. PMID:24506075
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Generation of Esr1-knockout rats using zinc finger nuclease-mediated genome editing.
Rumi, M A Karim; Dhakal, Pramod; Kubota, Kaiyu; Chakraborty, Damayanti; Lei, Tianhua; Larson, Melissa A; Wolfe, Michael W; Roby, Katherine F; Vivian, Jay L; Soares, Michael J
2014-05-01
Estrogens play pivotal roles in development and function of many organ systems, including the reproductive system. We have generated estrogen receptor 1 (Esr1)-knockout rats using zinc finger nuclease (ZFN) genome targeting. mRNAs encoding ZFNs targeted to exon 3 of Esr1 were microinjected into single-cell rat embryos and transferred to pseudopregnant recipients. Of 17 live births, 5 had biallelic and 1 had monoallelic Esr1 mutations. A founder with monoallelic mutations was backcrossed to a wild-type rat. Offspring possessed only wild-type Esr1 alleles or wild-type alleles and Esr1 alleles containing either 482 bp (Δ482) or 223 bp (Δ223) deletions, indicating mosaicism in the founder. These heterozygous mutants were bred for colony expansion, generation of homozygous mutants, and phenotypic characterization. The Δ482 Esr1 allele yielded altered transcript processing, including the absence of exon 3, aberrant splicing of exon 2 and 4, and a frameshift that generated premature stop codons located immediately after the codon for Thr157. ESR1 protein was not detected in homozygous Δ482 mutant uteri. ESR1 disruption affected sexually dimorphic postnatal growth patterns and serum levels of gonadotropins and sex steroid hormones. Both male and female Esr1-null rats were infertile. Esr1-null males had small testes with distended and dysplastic seminiferous tubules, whereas Esr1-null females possessed large polycystic ovaries, thread-like uteri, and poorly developed mammary glands. In addition, uteri of Esr1-null rats did not effectively respond to 17β-estradiol treatment, further demonstrating that the Δ482 Esr1 mutation created a null allele. This rat model provides a new experimental tool for investigating the pathophysiology of estrogen action.
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Identification and Characterization of Genes That Interact with Lin-12 in Caenorhabditis Elegans
Tax, F. E.; Thomas, J. H.; Ferguson, E. L.; Horvitz, H. R.
1997-01-01
We identified and characterized 14 extragenic mutations that suppressed the dominant egg-laying defect of certain lin-12 gain-of-function mutations. These suppressors defined seven genes: sup-17, lag-2, sel-4, sel-5, sel-6, sel-7 and sel-8. Mutations in six of the genes are recessive suppressors, whereas the two mutations that define the seventh gene, lag-2, are semi-dominant suppressors. These suppressor mutations were able to suppress other lin-12 gain-of-function mutations. The suppressor mutations arose at a very low frequency per gene, 10-50 times below the typical loss-of-function mutation frequency. The suppressor mutations in sup-17 and lag-2 were shown to be rare non-null alleles, and we present evidence that null mutations in these two genes cause lethality. Temperature-shift studies for two suppressor genes, sup-17 and lag-2, suggest that both genes act at approximately the same time as lin-12 in specifying a cell fate. Suppressor alleles of six of these genes enhanced a temperature-sensitive loss-of-function allele of glp-1, a gene related to lin-12 in structure and function. Our analysis of these suppressors suggests that the majority of these genes are part of a shared lin-12/glp-1 signal transduction pathway, or act to regulate the expression or stability of lin-12 and glp-1. PMID:9409830
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FGFR2 mutation in 46,XY sex reversal with craniosynostosis
Bagheri-Fam, Stefan; Ono, Makoto; Li, Li; Zhao, Liang; Ryan, Janelle; Lai, Raymond; Katsura, Yukako; Rossello, Fernando J.; Koopman, Peter; Scherer, Gerd; Bartsch, Oliver; Eswarakumar, Jacob V.P.; Harley, Vincent R.
2015-01-01
Patients with 46,XY gonadal dysgenesis (GD) exhibit genital anomalies, which range from hypospadias to complete male-to-female sex reversal. However, a molecular diagnosis is made in only 30% of cases. Heterozygous mutations in the human FGFR2 gene cause various craniosynostosis syndromes including Crouzon and Pfeiffer, but testicular defects were not reported. Here, we describe a patient whose features we would suggest represent a new FGFR2-related syndrome, craniosynostosis with XY male-to-female sex reversal or CSR. The craniosynostosis patient was chromosomally XY, but presented as a phenotypic female due to complete GD. DNA sequencing identified the FGFR2c heterozygous missense mutation, c.1025G>C (p.Cys342Ser). Substitution of Cys342 by Ser or other amino acids (Arg/Phe/Try/Tyr) has been previously reported in Crouzon and Pfeiffer syndrome. We show that the ‘knock-in’ Crouzon mouse model Fgfr2cC342Y/C342Y carrying a Cys342Tyr substitution displays XY gonadal sex reversal with variable expressivity. We also show that despite FGFR2c-Cys342Tyr being widely considered a gain-of-function mutation, Cys342Tyr substitution in the gonad leads to loss of function, as demonstrated by sex reversal in Fgfr2cC342Y/− mice carrying the knock-in allele on a null background. The rarity of our patient suggests the influence of modifier genes which exacerbated the testicular phenotype. Indeed, patient whole exome analysis revealed several potential modifiers expressed in Sertoli cells at the time of testis determination in mice. In summary, this study identifies the first FGFR2 mutation in a 46,XY GD patient. We conclude that, in certain rare genetic contexts, maintaining normal levels of FGFR2 signaling is important for human testis determination. PMID:26362256
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Alizadeh, Nazila; Mosaferi, Elnaz; Farzadi, Laya; Majidi, Jafar; Monfaredan, Amir; Yousefi, Bahman; Baradaran, Behzad
2016-07-01
Human leukocyte antigen-G (HLA-G) is a non-classical class I molecule highly expressed by extravillous cytotrophoblast cells. Due to a single base pair deletion, its function can be compensated by other isoforms. Investigating the frequency of null allele in Recurrent Miscarriage (RM) subjects could be useful in understanding the relationship between frequency of this allele and RM in a given population. This study aimed to determine the frequency of HLA-G*0105N null allele and its potential association with down-regulation of HLA-G in subjects with RM. Western blotting was used to assess the level of HLA-G protein expression. For investigating the frequency of HLA-G*0105N null allele in RM subjects, PCR-RFLP method was used. Exon 3 of HLA-G gene was amplified by polymerase chain reaction (PCR). Subsequently, PpuM-1 enzyme was employed to digest the PCR products and fragments were analyzed using gel electrophoresis. Digestion using restriction enzyme showed the presence of heterozygous HLA-G*0105N null allele in 10% of the test population. Western blotting results confirmed the decrease in expression of HLA-G in the placental tissue of subjects with RM compared to subjects who could give normal birth. The frequency of heterozygous HLA-G*0105N null allele was high to some extent in subjects with RM. The mutation rate in subjects suggested that there is a significant association between RM and frequency of mutations in this allele.
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Gauran, Iris Ivy M; Park, Junyong; Lim, Johan; Park, DoHwan; Zylstra, John; Peterson, Thomas; Kann, Maricel; Spouge, John L
2017-09-22
In recent mutation studies, analyses based on protein domain positions are gaining popularity over gene-centric approaches since the latter have limitations in considering the functional context that the position of the mutation provides. This presents a large-scale simultaneous inference problem, with hundreds of hypothesis tests to consider at the same time. This article aims to select significant mutation counts while controlling a given level of Type I error via False Discovery Rate (FDR) procedures. One main assumption is that the mutation counts follow a zero-inflated model in order to account for the true zeros in the count model and the excess zeros. The class of models considered is the Zero-inflated Generalized Poisson (ZIGP) distribution. Furthermore, we assumed that there exists a cut-off value such that smaller counts than this value are generated from the null distribution. We present several data-dependent methods to determine the cut-off value. We also consider a two-stage procedure based on screening process so that the number of mutations exceeding a certain value should be considered as significant mutations. Simulated and protein domain data sets are used to illustrate this procedure in estimation of the empirical null using a mixture of discrete distributions. Overall, while maintaining control of the FDR, the proposed two-stage testing procedure has superior empirical power. 2017 The Authors. Biometrics published by Wiley Periodicals, Inc. on behalf of International Biometric Society This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Parry, David A.; Poulter, James A.; Logan, Clare V.; Brookes, Steven J.; Jafri, Hussain; Ferguson, Christopher H.; Anwari, Babra M.; Rashid, Yasmin; Zhao, Haiqing; Johnson, Colin A.; Inglehearn, Chris F.; Mighell, Alan J.
2013-01-01
A combination of autozygosity mapping and exome sequencing identified a null mutation in SLC24A4 in a family with hypomineralized amelogenesis imperfect a (AI), a condition in which tooth enamel formation fails. SLC24A4 encodes a calcium transporter upregulated in ameloblasts during the maturation stage of amelogenesis. Screening of further AI families identified a missense mutation in the ion-binding site of SLC24A4 expected to severely diminish or abolish the ion transport function of the protein. Furthermore, examination of previously generated Slc24a4 null mice identified a severe defect in tooth enamel that reflects impaired amelogenesis. These findings support a key role for SLC24A4 in calcium transport during enamel formation. PMID:23375655
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Lack of formylated methionyl-tRNA has pleiotropic effects on Bacillus subtilis.
Cai, Yanfei; Chandrangsu, Pete; Gaballa, Ahmed; Helmann, John D
2017-02-01
Bacteria initiate translation using a modified amino acid, N-formylmethionine (fMet), adapted specifically for this function. Most proteins are processed co-translationally by peptide deformylase (PDF) to remove this modification. Although PDF activity is essential in WT cells and is the target of the antibiotic actinonin, bypass mutations in the fmt gene that eliminate the formylation of Met-tRNAMet render PDF dispensable. The extent to which the emergence of fmt bypass mutations might compromise the therapeutic utility of actinonin is determined, in part, by the effects of these bypass mutations on fitness. Here, we characterize the phenotypic consequences of an fmt null mutation in the model organism Bacillus subtilis. An fmt null mutant is defective for several post-exponential phase adaptive programmes including antibiotic resistance, biofilm formation, swarming and swimming motility and sporulation. In addition, a survey of well-characterized stress responses reveals an increased sensitivity to metal ion excess and oxidative stress. These diverse phenotypes presumably reflect altered synthesis or stability of key proteins involved in these processes.
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Hakobyan, Svetlana; Tortajada, Agustín; Harris, Claire L.; de Córdoba, Santiago Rodríguez; Morgan, B. Paul
2011-01-01
Atypical hemolytic uremic syndrome (aHUS) associates with complement alternative pathway defects in over 50% of cases. Mutations in factor H (fH) are most common, usually point mutations affecting complement surface regulation and sometimes null mutations in heterozygosity. The latter are difficult to identify; although consistently low plasma fH concentration is suggestive, definitive proof has required the demonstration that the mutant sequence does not express in vitro. Here, novel reagents and assays that distinguish and individually quantify the common fH-Y402H polymorphic variants were used to identify alleles of the CFH gene resulting in low or no (‘null’) expression of full-length fH, but normal or increased expression of the alternative splice product FHL-1, also detected in these assays. Their use in an aHUS cohort identified three Y402H heterozygotes with low or absent fH-H402 but normal or increased FHL-1 levels. Novel mutations in heterozygosis explained the null phenotype in two cases, confirmed by family studies in one. In the third case, family studies showed that a known mutation was present on the Y allele; the cause of the reduced expression of H allele was not found, although data suggested altered fH/FHL-1 splicing. In each family, inheritance of “low expression” or “null” alleles for fH strongly associated with aHUS. These assays provide a rapid means to identify fH expression defects in aHUS without resorting to gene sequencing or expression analysis. PMID:20703214
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Laval, Monique; Bel, Christophe; Faivre-Sarrailh, Catherine
2008-07-18
A complex of three cell adhesion molecules (CAMs) Neurexin IV(Nrx IV), Contactin (Cont) and Neuroglian (Nrg) is implicated in the formation of septate junctions between epithelial cells in Drosophila. These CAMs are interdependent for their localization at septate junctions and e.g. null mutation of nrx IV or cont induces the mislocalization of Nrg to the baso-lateral membrane. These mutations also result in ultrastructural alteration of the strands of septate junctions and breakdown of the paracellular barrier. Varicose (Vari) and Coracle (Cora), that both interact with the cytoplasmic tail of Nrx IV, are scaffolding molecules required for the formation of septate junctions. We conducted photobleaching experiments on whole living Drosophila embryos to analyze the membrane mobility of CAMs at septate junctions between epithelial cells. We show that GFP-tagged Nrg and Nrx IV molecules exhibit very stable association with septate junctions in wild-type embryos. Nrg-GFP is mislocalized to the baso-lateral membrane in nrx IV or cont null mutant embryos, and displays increased mobile fraction. Similarly, Nrx IV-GFP becomes distributed to the baso-lateral membrane in null mutants of vari and cora, and its mobile fraction is strongly increased. The loss of Vari, a MAGUK protein that interacts with the cytoplasmic tail of Nrx IV, has a stronger effect than the null mutation of nrx IV on the lateral mobility of Nrg-GFP. The strands of septate junctions display a stable behavior in vivo that may be correlated with their role of paracellular barrier. The membrane mobility of CAMs is strongly limited when they take part to the multimolecular complex forming septate junctions. This restricted lateral diffusion of CAMs depends on both adhesive interactions and clustering by scaffolding molecules. The lateral mobility of CAMs is strongly increased in embryos presenting alteration of septate junctions. The stronger effect of vari by comparison with nrx IV null mutation supports the hypothesis that this scaffolding molecule may cross-link different types of CAMs and play a crucial role in stabilizing the strands of septate junctions.
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Vastano, Valeria; Salzillo, Marzia; Siciliano, Rosa A; Muscariello, Lidia; Sacco, Margherita; Marasco, Rosangela
2014-01-01
Lactobacillus plantarum is among the species with a probiotic activity. Adhesion of probiotic bacteria to host tissues is an important principle for strain selection, because it represents a crucial step in the colonization process of either pathogens or commensals. Most bacterial adhesins are proteins, and a major target for them is fibronectin, an extracellular matrix glycoprotein. In this study we demonstrate that PDHB, a component of the pyruvate dehydrogenase complex, is a factor contributing to fibronectin-binding in L. plantarum LM3. By means of fibronectin overlay immunoblotting assay, we identified a L. plantarum LM3 surface protein with apparent molecular mass of 35 kDa. Mass spectrometric analysis shows that this protein is the pyruvate dehydrogenase E1 beta-subunit (PDHB). The corresponding pdhB gene is located in a 4-gene cluster encoding pyruvate dehydrogenase. In LM3-B1, carrying a null mutation in pdhB, the 35 kDa adhesin was not anymore detectable by immunoblotting assay. Nevertheless, the pdhB null mutation did not abolish pdhA, pdhC, and pdhD transcription in LM3-B1. By adhesion assays, we show that LM3-B1 cells bind to immobilized fibronectin less efficiently than wild type cells. Moreover, we show that pdhB expression is negatively regulated by the CcpA protein and is induced by bile. Copyright © 2013. Published by Elsevier GmbH.
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pKAMA-ITACHI Vectors for Highly Efficient CRISPR/Cas9-Mediated Gene Knockout in Arabidopsis thaliana
2017-01-01
The CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated 9) system is widely used as a tool for genome engineering in various organisms. A complex consisting of Cas9 and single guide RNA (sgRNA) induces a DNA double-strand break in a sequence-specific manner, resulting in knockout. Some binary vectors for CRISPR/Cas9 in plants have been reported, but there is a problem with low efficiency. Here, we present a newly developed, highly efficient CRISPR/Cas9 vector for Arabidopsis thaliana, pKAMA-ITACHI Red (pKIR), harboring the RIBOSOMAL PROTEIN S5 A (RPS5A) promoter to drive Cas9. The RPS5A promoter maintains high constitutive expression at all developmental stages starting from the egg cell and including meristematic cells. Even in the T1 generation, pKIR induced null phenotypes in some genes: PHYTOENE DESATURASE 3 (PDS3), AGAMOUS (AG) and DUO POLLEN 1 (DUO1). Mutations induced by pKIR were carried in the germ cell line of the T1 generation. Surprisingly, in some lines, 100% of the T2 plants had the adh1 (ALCOHOL DEHYDROGENASE 1) null phenotype, indicating that pKIR strongly induced heritable mutations. Cas9-free T2 mutant plants were obtained by removing T2 seeds expressing a fluorescent marker in pKIR. Our results suggest that the pKIR system is a powerful molecular tool for genome engineering in Arabidopsis. PMID:27856772
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Wu, Fenfen; Mi, Wentao; Fu, Yu; Struyk, Arie
2016-01-01
Over 60 mutations of SCN4A encoding the NaV1.4 sodium channel of skeletal muscle have been identified in patients with myotonia, periodic paralysis, myasthenia, or congenital myopathy. Most mutations are missense with gain-of-function defects that cause susceptibility to myotonia or periodic paralysis. Loss-of-function from enhanced inactivation or null alleles is rare and has been associated with myasthenia and congenital myopathy, while a mix of loss and gain of function changes has an uncertain relation to hypokalaemic periodic paralysis. To better define the functional consequences for a loss-of-function, we generated NaV1.4 null mice by deletion of exon 12. Heterozygous null mice have latent myasthenia and a right shift of the force-stimulus relation, without evidence of periodic paralysis. Sodium current density was half that of wild-type muscle and no compensation by retained expression of the foetal NaV1.5 isoform was detected. Mice null for NaV1.4 did not survive beyond the second postnatal day. This mouse model shows remarkable preservation of muscle function and viability for haploinsufficiency of NaV1.4, as has been reported in humans, with a propensity for pseudo-myasthenia caused by a marginal Na+ current density to support sustained high-frequency action potentials in muscle. PMID:27048647
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Redaelli, Veronica; Rossi, Giacomina; Maderna, Emanuela; Kovacs, Gabor G; Piccoli, Elena; Caroppo, Paola; Cacciatore, Francesca; Spinello, Sonia; Grisoli, Marina; Sozzi, Giuliano; Salmaggi, Andrea; Tagliavini, Fabrizio; Giaccone, Giorgio
2018-01-01
Null mutations in progranulin gene (GRN) reduce the progranulin production resulting in haploinsufficiency and are tightly associated with tau-negative frontotemporal lobar degeneration with TAR DNA-binding protein 43-positive inclusions (FTLD-TDP). Missense mutations of GRN were also identified, but their effects are not completely clear, in particular unanswered is the question of what neuropathology they elicit, also considering that their occurrence has been reported in patients with typical clinical features of Alzheimer disease. They describe two fraternal twins carrying the missense GRN Cys139Arg mutation affected by late-onset dementia and we report the neuropathological study of one of them. Both patients were examined by neuroimaging, neuropsychological assessment and genetic analysis of GRN and other genes associated with dementia. The brain of one was obtained at autopsy and examined neuropathologically. One sister presented clinical and MRI features leading to the diagnosis of Alzheimer disease. The other underwent autopsy and the brain showed neuropathological hallmarks of Alzheimer disease with abundant Aβ-amyloid deposition and Braak stage V of neurofibrillary pathology, in the absence of the hallmark lesions of FTLD-TDP. Their findings may contribute to better clarify the role of progranulin in neurodegenerative diseases indicating that some GRN mutations, in particular missense ones, may act as strong risk factor for Alzheimer disease rather than induce FTLD-TDP. © 2016 International Society of Neuropathology.
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Nishiguchi, Koji M; Friedman, James S; Sandberg, Michael A; Swaroop, Anand; Berson, Eliot L; Dryja, Thaddeus P
2004-12-21
Mice lacking the transcription factor Nrl have no rod photoreceptors and an increased number of short-wavelength-sensitive cones. Missense mutations in NRL are associated with autosomal dominant retinitis pigmentosa; however, the phenotype associated with the loss of NRL function in humans has not been reported. We identified two siblings who carried two allelic mutations: a predicted null allele (L75fs) and a missense mutation (L160P) altering a highly conserved residue in the domain involved in DNA-binding-site recognition. In vitro luciferase reporter assays demonstrated that the NRL-L160P mutant had severely reduced transcriptional activity compared with the WT NRL protein, consistent with a severe loss of function. The affected patients had night blindness since early childhood, consistent with a severe reduction in rod function. Color vision was normal, suggesting the presence of all cone color types; nevertheless, a comparison of central visual fields evaluated with white-on-white and blue-on-yellow light stimuli was consistent with a relatively enhanced function of short-wavelength-sensitive cones in the macula. The fundi had signs of retinal degeneration (such as vascular attenuation) and clusters of large, clumped, pigment deposits in the peripheral fundus at the level of the retinal pigment epithelium (clumped pigmentary retinal degeneration). Our report presents an unusual clinical phenotype in humans with loss-of-function mutations in NRL.
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Boutzen, Héléna; Saland, Estelle; Larrue, Clément; de Toni, Fabienne; Gales, Lara; Castelli, Florence A.; Cathebas, Mathilde; Zaghdoudi, Sonia; Stuani, Lucille; Kaoma, Tony; Riscal, Romain; Yang, Guangli; Hirsch, Pierre; David, Marion; De Mas-Mansat, Véronique; Delabesse, Eric; Vallar, Laurent; Delhommeau, François; Jouanin, Isabelle; Ouerfelli, Ouathek; Le Cam, Laurent; Linares, Laetitia K.; Junot, Christophe; Portais, Jean-Charles; Vergez, François; Récher, Christian
2016-01-01
Acute myeloid leukemia (AML) is characterized by the accumulation of malignant blasts with impaired differentiation programs caused by recurrent mutations, such as the isocitrate dehydrogenase (IDH) mutations found in 15% of AML patients. These mutations result in the production of the oncometabolite (R)-2-hydroxyglutarate (2-HG), leading to a hypermethylation phenotype that dysregulates hematopoietic differentiation. In this study, we identified mutant R132H IDH1-specific gene signatures regulated by key transcription factors, particularly CEBPα, involved in myeloid differentiation and retinoid responsiveness. We show that treatment with all-trans retinoic acid (ATRA) at clinically achievable doses markedly enhanced terminal granulocytic differentiation in AML cell lines, primary patient samples, and a xenograft mouse model carrying mutant IDH1. Moreover, treatment with a cell-permeable form of 2-HG sensitized wild-type IDH1 AML cells to ATRA-induced myeloid differentiation, whereas inhibition of 2-HG production significantly reduced ATRA effects in mutant IDH1 cells. ATRA treatment specifically decreased cell viability and induced apoptosis of mutant IDH1 blasts in vitro. ATRA also reduced tumor burden of mutant IDH1 AML cells xenografted in NOD–Scid–IL2rγnull mice and markedly increased overall survival, revealing a potent antileukemic effect of ATRA in the presence of IDH1 mutation. This therapeutic strategy holds promise for this AML patient subgroup in future clinical studies. PMID:26951332
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Yeh, Ying-Chun; Kinoshita, Masato; Ng, Tze Hann; Chang, Yu-Hsuan; Maekawa, Shun; Chiang, Yi-An; Aoki, Takashi; Wang, Han-Ching
2017-09-12
Myostatin (MSTN) suppresses skeletal muscle development and growth in mammals, but its role in fish is less well understood. Here we used CRISPR/Cas9 to mutate the MSTN gene in medaka (Oryzias latipes) and evaluate subsequent growth performance. We produced mutant F0 fish that carried different frameshifts in the OlMSTN coding sequence and confirmed the heritability of the mutant genotypes to the F1 generation. Two F1 fish with the same heterozygous frame-shifted genomic mutations (a 22 bp insertion in one allele; a 32 bp insertion in the other) were then crossbred to produce subsequent generations (F2~F5). Body length and weight of the MSTN -/- F4 medaka were significantly higher than in the wild type fish, and muscle fiber density in the inner and outer compartments of the epaxial muscles was decreased, suggesting that MSTN null mutation induces muscle hypertrophy. From 3~4 weeks post hatching (wph), the expression of three major myogenic related factors (MRFs), MyoD, Myf5 and Myogenin, was also significantly upregulated. Some medaka had a spinal deformity, and we also observed a trade-off between growth and immunity in MSTN -/- F4 medaka. Reproduction was unimpaired in the fast-growth phenotypes.
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Control of Cell Morphology: Signalling by the Receptor Notch.
1996-10-01
missense mutations or small deletions at the extreme C-terminus of NOTCH, and lie within the minimal region that includes the C-terminal binding site for...20 Figure 4. Genetic interaction of null and hypomorphic alleles of Notch with abl mutations ...wide variety of cell types during Drosophila embryogenesis [1, 2]. Mutations in the Notch gene lead to severe defects in cell identity in the nervous
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Willing, M.C.; Deschenes, S.P.; Roberts, E.J.
Nonsense and frameshift mutations, which predict premature termination of translation, often cause a dramatic reduction in the amount of transcript from the mutant allele (nonsense-mediated mRNA decay). In some genes, these mutations also influence RNA splicing and induce skipping of the exon that contains the nonsense codon. To begin to dissect how premature termination alters the metabolism of RNA from the COL1A1 gene, we studied nonsense and frameshift mutations distributed over exons 11-49 of the gene. These mutations were originally identified in 10 unrelated families with osteogenesis imperfecta (OI) type I. We observed marked reduction in steady-state amounts of mRNAmore » from the mutant allele in both total cellular and nuclear RNA extracts of cells from affected individuals, suggesting that nonsense-mediated decay of COL1A1 RNA is a nuclear phenomenon. Position of the mutation within the gene did not influence this observation. None of the mutations induced skipping of either the exon containing the mutation or, for the frameshifts, the downstream exons with the new termination sites. Our data suggest that nonsense and frameshift mutations throughout most of the COL1A1 gene result in a null allele, which is associated with the predictable mild clinical phenotype, OI type I. 42 refs., 6 figs., 1 tab.« less
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Association of PKD2 (polycystin 2) mutations with left-right laterality defects.
Bataille, Stanislas; Demoulin, Nathalie; Devuyst, Olivier; Audrézet, Marie-Pierre; Dahan, Karin; Godin, Michel; Fontès, Michel; Pirson, Yves; Burtey, Stéphane
2011-09-01
Mutations in the PKD1 (polycystin 1) and PKD2 (polycystin 2) genes cause autosomal dominant polycystic kidney disease (ADPKD). Most Pkd2-null mouse embryos present with left-right laterality defects. For the first time, we report the association of ADPKD resulting from a mutation in PKD2 and left-right asymmetry defects. PKD1 and PKD2 were screened for mutations or large genomic rearrangements in 3 unrelated patients with ADPKD presenting with laterality defects: dextrocardia in one and situs inversus totalis in 2 others. A large gene deletion, a single-exon duplication, and an in-frame duplication respectively, were found in the 3 patients. These polymorphisms were found in all tested relatives with ADPKD, but were absent in unaffected related individuals. No left-right anomalies were found in other members of the 3 families. A possible association between heterotaxia and a PKD2 mutation in our 3 patients is suggested by: (1) the existence of laterality defects in Pkd2-null mouse and zebrafish models and (2) detection of a pathogenic PKD2 mutation in the 3 probands, although PKD2 mutations account for only 15% of ADPKD families. The presence of left-right laterality defects should be systematically screened in larger cohorts of patients with ADPKD harboring PKD2 mutations. Copyright © 2011 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.
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Alizadeh, Nazila; Mosaferi, Elnaz; Farzadi, Laya; Majidi, Jafar; Monfaredan, Amir; Yousefi, Bahman; Baradaran, Behzad
2016-01-01
Background: Human leukocyte antigen-G (HLA-G) is a non-classical class I molecule highly expressed by extravillous cytotrophoblast cells. Due to a single base pair deletion, its function can be compensated by other isoforms. Investigating the frequency of null allele in Recurrent Miscarriage (RM) subjects could be useful in understanding the relationship between frequency of this allele and RM in a given population. Objective: This study aimed to determine the frequency of HLA-G*0105N null allele and its potential association with down-regulation of HLA-G in subjects with RM. Materials and Methods: Western blotting was used to assess the level of HLA-G protein expression. For investigating the frequency of HLA-G*0105N null allele in RM subjects, PCR-RFLP method was used. Exon 3 of HLA-G gene was amplified by polymerase chain reaction (PCR). Subsequently, PpuM-1 enzyme was employed to digest the PCR products and fragments were analyzed using gel electrophoresis. Results: Digestion using restriction enzyme showed the presence of heterozygous HLA-G*0105N null allele in 10% of the test population. Western blotting results confirmed the decrease in expression of HLA-G in the placental tissue of subjects with RM compared to subjects who could give normal birth. Conclusion: The frequency of heterozygous HLA-G*0105N null allele was high to some extent in subjects with RM. The mutation rate in subjects suggested that there is a significant association between RM and frequency of mutations in this allele. PMID:27525330
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Mutations associated with base excision repair deficiency and methylation-induced genotoxic stress
Sobol, Robert W.; Watson, David E.; Nakamura, Jun; Yakes, F. Michael; Hou, Esther; Horton, Julie K.; Ladapo, Joseph; Van Houten, Bennett; Swenberg, James A.; Tindall, Kenneth R.; Samson, Leona D.; Wilson, Samuel H.
2002-01-01
The long-term effect of exposure to DNA alkylating agents is entwined with the cell's genetic capacity for DNA repair and appropriate DNA damage responses. A unique combination of environmental exposure and deficiency in these responses can lead to genomic instability; this “gene–environment interaction” paradigm is a theme for research on chronic disease etiology. In the present study, we used mouse embryonic fibroblasts with a gene deletion in the base excision repair (BER) enzymes DNA β-polymerase (β-pol) and alkyladenine DNA glycosylase (AAG), along with exposure to methyl methanesulfonate (MMS) to study mutagenesis as a function of a particular gene–environment interaction. The β-pol null cells, defective in BER, exhibit a modest increase in spontaneous mutagenesis compared with wild-type cells. MMS exposure increases mutant frequency in β-pol null cells, but not in isogenic wild-type cells; UV light exposure or N-methyl-N′-nitro-N-nitrosoguanidine exposure increases mutant frequency similarly in both cell lines. The MMS-induced increase in mutant frequency in β-pol null cells appears to be caused by DNA lesions that are AAG substrates, because overexpression of AAG in β-pol null cells eliminates the effect. In contrast, β-pol/AAG double null cells are slightly more mutable than the β-pol null cells after MMS exposure. These results illustrate that BER plays a role in protecting mouse embryonic fibroblast cells against methylation-induced mutations and characterize the effect of a particular combination of BER gene defect and environmental exposure. PMID:11983862
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Godfrey, Jack D; Morton, Jennifer P; Wilczynska, Ania; Sansom, Owen J; Bushell, Martin D
2018-05-29
Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive disease with poor prognostic implications. This is partly due to a large proportion of PDACs carrying mutations in TP53, which impart gain-of-function characteristics that promote metastasis. There is evidence that microRNAs (miRNAs) may play a role in both gain-of-function TP53 mutations and metastasis, but this has not been fully explored in PDAC. Here we set out to identify miRNAs which are specifically dysregulated in metastatic PDAC. To achieve this, we utilised established mouse models of PDAC to profile miRNA expression in primary tumours expressing the metastasis-inducing mutant p53 R172H and compared these to two control models carrying mutations, which promote tumour progression but do not induce metastasis. We show that a subset of miRNAs are dysregulated in mouse PDAC tumour tissues expressing mutant p53 R172H , primary cell lines derived from mice with the same mutations and in TP53 null cells with ectopic expression of the orthologous human mutation, p53 R175H . Specifically, miR-142-3p is downregulated in all of these experimental models. We found that DNA methyltransferase 1 (Dnmt1) is upregulated in tumour tissue and cell lines, which express p53 R172H . Inhibition or depletion of Dnmt1 restores miR-142-3p expression. Overexpression of miR-142-3p attenuates the invasive capacity of p53 R172H -expressing tumour cells. MiR-142-3p dysregulation is known to be associated with cancer progression, metastasis and the miRNA is downregulated in patients with PDAC. Here we link TP53 gain-of-function mutations to Dnmt1 expression and in turn miR-142-3p expression. Additionally, we show a correlation between expression of these genes and patient survival, suggesting that they may have potential to be therapeutic targets.
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Jackson, Sha-Ron; Lee, Jooeun; Reddy, Raghava; Williams, Genevieve N.; Kikuchi, Alexander; Freiberg, Yael; Warburton, David
2011-01-01
Telomerase mutations and significantly shortened chromosomal telomeres have recently been implicated in human lung pathologies. Natural telomere shortening is an inevitable consequence of aging, which is also a risk factor for development of lung disease. However, the impact of shortened telomeres and telomerase dysfunction on the ability of lung cells to respond to significant challenge is still largely unknown. We have previously shown that lungs of late generation, telomerase null B6.Cg-Terctm1Rdp mice feature alveolar simplification and chronic stress signaling at baseline, a phenocopy of aged lung. To determine the role telomerase plays when the lung is challenged, B6.Cg-Terctm1Rdp mice carrying shortened telomeres and wild-type controls were subjected to partial pneumonectomy. We found that telomerase activity was strongly induced in alveolar epithelial type 2 cells (AEC2) of the remaining lung immediately following surgery. Eighty-six percent of wild-type animals survived the procedure and exhibited a burst of early compensatory growth marked by upregulation of proliferation, stress response, and DNA repair pathways in AEC2. In B6.Cg-Terctm1Rdp mice carrying shortened telomeres, response to pneumonectomy was characterized by decreased survival, diminished compensatory lung growth, attenuated distal lung progenitor cell response, persistent DNA damage, and cell growth arrest. Overall, survival correlated strongly with telomere length. We conclude that functional telomerase and properly maintained telomeres play key roles in both long-term survival and the early phase of compensatory lung growth following partial pneumonectomy. PMID:21460122
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Ward, Stephen L; Scheuner, Donalyn; Poppers, Jeremy; Kaufman, Randal J; Mohr, Ian; Leib, David A
2003-04-01
In animal models of herpes simplex virus type 1 (HSV-1) infection, ICP34.5-null viruses are avirulent and also fail to grow in a variety of cultured cells due to their inability to prevent RNA-dependent protein kinase (PKR)-mediated inhibition of protein synthesis. We show here that the inability of ICP34.5 mutants to grow in vitro is due specifically to the accumulation of phosphorylated eIF2 alpha. Mutations suppressing the in vitro phenotype of ICP34.5-null mutants have been described which map to the unique short region of the HSV-1 genome, resulting in dysregulated expression of the US11 gene. Despite the inability of the suppressor mutation to suppress the avirulent phenotype of the ICP34.5-null parental virus following intracranial inoculation, the suppressor mutation enhanced virus growth in the cornea, trigeminal ganglia, and periocular skin following corneal infection compared to that with the ICP34.5-null virus. The phosphorylation state of eIF2 alpha following in vitro infection with the suppressor virus was examined to determine if in vivo differences could be attributed to differential regulation of eIF2 alpha phosphorylation. The suppressor virus prevented accumulation of phosphorylated eIF2 alpha, while the wild-type virus substantially reduced eIF2 alpha phosphorylation levels. These data suggest that US11 functions as a PKR antagonist in vivo, although its activity may be modulated by tissue-specific differences in translation regulation.
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Ward, Stephen L.; Scheuner, Donalyn; Poppers, Jeremy; Kaufman, Randal J.; Mohr, Ian; Leib, David A.
2003-01-01
In animal models of herpes simplex virus type 1 (HSV-1) infection, ICP34.5-null viruses are avirulent and also fail to grow in a variety of cultured cells due to their inability to prevent RNA-dependent protein kinase (PKR)-mediated inhibition of protein synthesis. We show here that the inability of ICP34.5 mutants to grow in vitro is due specifically to the accumulation of phosphorylated eIF2α. Mutations suppressing the in vitro phenotype of ICP34.5-null mutants have been described which map to the unique short region of the HSV-1 genome, resulting in dysregulated expression of the US11 gene. Despite the inability of the suppressor mutation to suppress the avirulent phenotype of the ICP34.5-null parental virus following intracranial inoculation, the suppressor mutation enhanced virus growth in the cornea, trigeminal ganglia, and periocular skin following corneal infection compared to that with the ICP34.5-null virus. The phosphorylation state of eIF2α following in vitro infection with the suppressor virus was examined to determine if in vivo differences could be attributed to differential regulation of eIF2α phosphorylation. The suppressor virus prevented accumulation of phosphorylated eIF2α, while the wild-type virus substantially reduced eIF2α phosphorylation levels. These data suggest that US11 functions as a PKR antagonist in vivo, although its activity may be modulated by tissue-specific differences in translation regulation. PMID:12663769
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Circulating progranulin as a biomarker for neurodegenerative diseases.
Ghidoni, Roberta; Paterlini, Anna; Benussi, Luisa
2012-01-01
Progranulin is a growth factor involved in the regulation of multiple processes including tumorigenesis, wound repair, development, and inflammation. The recent discovery that mutations in the gene encoding for progranulin (GRN) cause frontotemporal lobar degeneration (FTLD), and other neurodegenerative diseases leading to dementia, has brought renewed interest in progranulin and its functions in the central nervous system. GRN null mutations cause protein haploinsufficiency, leading to a significant decrease in progranulin levels that can be detected in plasma, serum and cerebrospinal fluid (CSF) of mutation carriers. The dosage of circulating progranulin sped up the identification of GRN mutations thus favoring genotype-phenotype correlation studies. Researchers demonstrated that, in GRN null mutation carriers, the shortage of progranulin invariably precedes clinical symptoms and thus mutation carriers are "captured" regardless of their disease status. GRN is a particularly appealing gene for drug targeting, in the way that boosting its expression may be beneficial for mutation carriers, preventing or delaying the onset of GRN-related neurodegenerative diseases. Physiological regulation of progranulin expression level is only partially known. Progranulin expression reflects mutation status and, intriguingly, its levels can be modulated by some additional factor (i.e. genetic background; drugs). Thus, factors increasing the production and secretion of progranulin from the normal gene are promising potential therapeutic avenues. In conclusion, peripheral progranulin is a nonintrusive highly accurate biomarker for early identification of mutation carriers and for monitoring future treatments that might boost the level of this protein.
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Circulating progranulin as a biomarker for neurodegenerative diseases
Ghidoni, Roberta; Paterlini, Anna; Benussi, Luisa
2012-01-01
Progranulin is a growth factor involved in the regulation of multiple processes including tumorigenesis, wound repair, development, and inflammation. The recent discovery that mutations in the gene encoding for progranulin (GRN) cause frontotemporal lobar degeneration (FTLD), and other neurodegenerative diseases leading to dementia, has brought renewed interest in progranulin and its functions in the central nervous system. GRN null mutations cause protein haploinsufficiency, leading to a significant decrease in progranulin levels that can be detected in plasma, serum and cerebrospinal fluid (CSF) of mutation carriers. The dosage of circulating progranulin sped up the identification of GRN mutations thus favoring genotype-phenotype correlation studies. Researchers demonstrated that, in GRN null mutation carriers, the shortage of progranulin invariably precedes clinical symptoms and thus mutation carriers are “captured” regardless of their disease status. GRN is a particularly appealing gene for drug targeting, in the way that boosting its expression may be beneficial for mutation carriers, preventing or delaying the onset of GRN-related neurodegenerative diseases. Physiological regulation of progranulin expression level is only partially known. Progranulin expression reflects mutation status and, intriguingly, its levels can be modulated by some additional factor (i.e. genetic background; drugs). Thus, factors increasing the production and secretion of progranulin from the normal gene are promising potential therapeutic avenues. In conclusion, peripheral progranulin is a nonintrusive highly accurate biomarker for early identification of mutation carriers and for monitoring future treatments that might boost the level of this protein. PMID:23383391
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Starrett, Gabriel J; Luengas, Elizabeth M; McCann, Jennifer L; Ebrahimi, Diako; Temiz, Nuri A; Love, Robin P; Feng, Yuqing; Adolph, Madison B; Chelico, Linda; Law, Emily K; Carpenter, Michael A; Harris, Reuben S
2016-09-21
Cytosine mutations within TCA/T motifs are common in cancer. A likely cause is the DNA cytosine deaminase APOBEC3B (A3B). However, A3B-null breast tumours still have this mutational bias. Here we show that APOBEC3H haplotype I (A3H-I) provides a likely solution to this paradox. A3B-null tumours with this mutational bias have at least one copy of A3H-I despite little genetic linkage between these genes. Although deemed inactive previously, A3H-I has robust activity in biochemical and cellular assays, similar to A3H-II after compensation for lower protein expression levels. Gly105 in A3H-I (versus Arg105 in A3H-II) results in lower protein expression levels and increased nuclear localization, providing a mechanism for accessing genomic DNA. A3H-I also associates with clonal TCA/T-biased mutations in lung adenocarcinoma suggesting this enzyme makes broader contributions to cancer mutagenesis. These studies combine to suggest that A3B and A3H-I, together, explain the bulk of 'APOBEC signature' mutations in cancer.
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Distinct Brca1 Mutations Differentially Reduce Hematopoietic Stem Cell Function.
Mgbemena, Victoria E; Signer, Robert A J; Wijayatunge, Ranjula; Laxson, Travis; Morrison, Sean J; Ross, Theodora S
2017-01-24
BRCA1 is a well-known DNA repair pathway component and a tissue-specific tumor suppressor. However, its role in hematopoiesis is uncertain. Here, we report that a cohort of patients heterozygous for BRCA1 mutations experienced more hematopoietic toxicity from chemotherapy than those with BRCA2 mutations. To test whether this reflects a requirement for BRCA1 in hematopoiesis, we generated mice with Brca1 mutations in hematopoietic cells. Mice homozygous for a null Brca1 mutation in the embryonic hematopoietic system (Vav1-iCre;Brca1 F22-24/F22-24 ) developed hematopoietic defects in early adulthood that included reduced hematopoietic stem cells (HSCs). Although mice homozygous for a huBRCA1 knockin allele (Brca1 BRCA1/BRCA1 ) were normal, mice with a mutant huBRCA1/5382insC allele and a null allele (Mx1-Cre;Brca1 F22-24/5382insC ) had severe hematopoietic defects marked by a complete loss of hematopoietic stem and progenitor cells. Our data show that Brca1 is necessary for HSC maintenance and normal hematopoiesis and that distinct mutations lead to different degrees of hematopoietic dysfunction. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.
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Molecular defects of the CYP21A2 gene in Greek-Cypriot patients with congenital adrenal hyperplasia.
Skordis, Nicos; Kyriakou, Andreas; Tardy, Véronique; Ioannou, Yiannis S; Varvaresou, Athanasia; Dracopoulou-Vabouli, Maria; Patsalis, Philippos C; Shammas, Christos; Neocleous, Vassos; Phylactou, Leonidas A
2011-01-01
To determine the mutations in the CYP21A2 gene in Greek-Cypriots with congenital adrenal hyperplasia (CAH) and attempt a genotype-phenotype correlation. Molecular analysis was performed by multiplex ligation-dependent probe amplification and direct sequencing of PCR products of the CYP21A2 gene in 32 CAH patients. The most frequent genetic defect in the classic salt-wasting and simple virilizing forms was the IVS2-13A/C>G (55%) mutation, followed by Large lesion (20%) and in the non-classical form, the p.V281L (79.5%). Genotypes were categorized in 4 mutation groups (null, A, B and C). All 3 patients in the null group manifested the salt-wasting form and all 6 patients in mutation group A presented with the classical form. One patient in group B had the simple virilizing form and 22 patients in group C exhibited the non-classical form. The spectrum of mutations of the CYP21A2 gene in our population is comparable to the most common reported in similar ethnic groups. The knowledge of the ethnic specificity of the CYP21A2 mutations represents a valuable diagnostic tool for all forms of CAH. Copyright © 2010 S. Karger AG, Basel.
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TET2 mutations predict response to hypomethylating agents in myelodysplastic syndrome patients
Lord, Allegra; Stevenson, Kristen; Bar-Natan, Michal; Pérez-Ladaga, Albert; Zaneveld, Jacques; Wang, Hui; Caughey, Bennett; Stojanov, Petar; Getz, Gad; Garcia-Manero, Guillermo; Kantarjian, Hagop; Chen, Rui; Stone, Richard M.; Neuberg, Donna; Steensma, David P.; Ebert, Benjamin L.
2014-01-01
Only a minority of myelodysplastic syndrome (MDS) patients respond to hypomethylating agents (HMAs), but strong predictors of response are unknown. We sequenced 40 recurrently mutated myeloid malignancy genes in tumor DNA from 213 MDS patients collected before treatment with azacitidine (AZA) or decitabine (DEC). Mutations were examined for association with response and overall survival. The overall response rate of 47% was not different between agents. Clonal TET2 mutations predicted response (odds ratio [OR] 1.99, P = .036) when subclones unlikely to be detected by Sanger sequencing (allele fraction <10%) were treated as wild-type (WT). Response rates were highest in the subset of TET2 mutant patients without clonal ASXL1 mutations (OR 3.65, P = .009). Mutations of TP53 (hazard ratio [HR] 2.01, P = .002) and PTPN11 (HR 3.26, P = .006) were associated with shorter overall survival but not drug response. Murine-competitive bone marrow transplantation followed by treatment with AZA demonstrated that Tet2-null cells have an engraftment advantage over Tet2-WT cells. AZA significantly decreased this advantage for Tet2-null cells (P = .002) but not Tet2-WT cells (P = .212). Overall, Tet2 loss appears to sensitize cells to treatment with AZA in vivo, and TET2 mutations can identify patients more likely to respond to HMAs. PMID:25224413
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TET2 mutations predict response to hypomethylating agents in myelodysplastic syndrome patients.
Bejar, Rafael; Lord, Allegra; Stevenson, Kristen; Bar-Natan, Michal; Pérez-Ladaga, Albert; Zaneveld, Jacques; Wang, Hui; Caughey, Bennett; Stojanov, Petar; Getz, Gad; Garcia-Manero, Guillermo; Kantarjian, Hagop; Chen, Rui; Stone, Richard M; Neuberg, Donna; Steensma, David P; Ebert, Benjamin L
2014-10-23
Only a minority of myelodysplastic syndrome (MDS) patients respond to hypomethylating agents (HMAs), but strong predictors of response are unknown. We sequenced 40 recurrently mutated myeloid malignancy genes in tumor DNA from 213 MDS patients collected before treatment with azacitidine (AZA) or decitabine (DEC). Mutations were examined for association with response and overall survival. The overall response rate of 47% was not different between agents. Clonal TET2 mutations predicted response (odds ratio [OR] 1.99, P = .036) when subclones unlikely to be detected by Sanger sequencing (allele fraction <10%) were treated as wild-type (WT). Response rates were highest in the subset of TET2 mutant patients without clonal ASXL1 mutations (OR 3.65, P = .009). Mutations of TP53 (hazard ratio [HR] 2.01, P = .002) and PTPN11 (HR 3.26, P = .006) were associated with shorter overall survival but not drug response. Murine-competitive bone marrow transplantation followed by treatment with AZA demonstrated that Tet2-null cells have an engraftment advantage over Tet2-WT cells. AZA significantly decreased this advantage for Tet2-null cells (P = .002) but not Tet2-WT cells (P = .212). Overall, Tet2 loss appears to sensitize cells to treatment with AZA in vivo, and TET2 mutations can identify patients more likely to respond to HMAs. © 2014 by The American Society of Hematology.
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Manfroi, Silvia; Scarcello, Antonio; Pagliaro, Pasqualepaolo
2015-10-01
Molecular genetic studies on Duffy blood group antigens have identified mutations underlying rare FY*Null and FY*X alleles. FY*Null has a high frequency in Blacks, especially from sub-Saharan Africa, while its frequency is not defined in Caucasians. FY*X allele, associated with Fy(a-b+w) phenotype, has a frequency of 2-3.5% in Caucasian people while it is absent in Blacks. During the project of extensive blood group genotyping in patients affected by hemoglobinopathies, we identified FY*X/FY*Null and FY*A/FY*Null genotypes in a Caucasian thalassemic family from Sardinia. We speculate on the frequency of FY*X and FY*Null alleles in Caucasian and Black people; further, we focused on the association of FY*X allele with weak Fyb antigen expression on red blood cells and its identification performing high sensitivity serological typing methods or genotyping. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Lack of formylated methionyl-tRNA has pleiotropic effects on Bacillus subtilis
Cai, Yanfei; Chandrangsu, Pete; Gaballa, Ahmed; Helmann, John D
2017-01-01
Bacteria initiate translation using a modified amino acid, N-formylmethionine (fMet), adapted specifically for this function. Most proteins are processed co-translationally by peptide deformylase (PDF) to remove this modification. Although PDF activity is essential in WT cells and is the target of the antibiotic actinonin, bypass mutations in the fmt gene that eliminate the formylation of Met-tRNAMet render PDF dispensable. The extent to which the emergence of fmt bypass mutations might compromise the therapeutic utility of actinonin is determined, in part, by the effects of these bypass mutations on fitness. Here, we characterize the phenotypic consequences of an fmt null mutation in the model organism Bacillus subtilis. An fmt null mutant is defective for several post-exponential phase adaptive programmes including antibiotic resistance, biofilm formation, swarming and swimming motility and sporulation. In addition, a survey of well-characterized stress responses reveals an increased sensitivity to metal ion excess and oxidative stress. These diverse phenotypes presumably reflect altered synthesis or stability of key proteins involved in these processes. PMID:27983482
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Sferruzzi-Perri, Amanda N; Macpherson, Anne M; Roberts, Claire T; Robertson, Sarah A
2009-07-01
Genetic deficiency in granulocyte-macrophage colony-stimulating factor (CSF2, GM-CSF) results in altered placental structure in mice. To investigate the mechanism of action of CSF2 in placental morphogenesis, the placental gene expression and cell composition were examined in Csf2 null mutant and wild-type mice. Microarray and quantitative RT-PCR analyses on Embryonic Day (E) 13 placentae revealed that the Csf2 null mutation caused altered expression of 17 genes not previously known to be associated with placental development, including Mid1, Cd24a, Tnfrsf11b, and Wdfy1. Genes controlling trophoblast differentiation (Ascl2, Tcfeb, Itgav, and Socs3) were also differentially expressed. The CSF2 ligand and the CSF2 receptor alpha subunit were predominantly synthesized in the placental junctional zone. Altered placental structure in Csf2 null mice at E15 was characterized by an expanded junctional zone and by increased Cx31(+) glycogen cells and cyclin-dependent kinase inhibitor 1C (CDKN1C(+), P57(Kip2+)) giant cells, accompanied by elevated junctional zone transcription of genes controlling spongiotrophoblast and giant cell differentiation and secretory function (Ascl2, Hand1, Prl3d1, and Prl2c2). Granzyme genes implicated in tissue remodeling and potentially in trophoblast invasion (Gzmc, Gzme, and Gzmf) were downregulated in the junctional zone of Csf2 null mutant placentae. These data demonstrate aberrant placental gene expression in Csf2 null mutant mice that is associated with altered differentiation and/or functional maturation of junctional zone trophoblast lineages, glycogen cells, and giant cells. We conclude that CSF2 is a regulator of trophoblast differentiation and placental development, which potentially influences the functional capacity of the placenta to support optimal fetal growth in pregnancy.
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McKie, Arthur B; Alsaedi, Atif; Vogt, Julie; Stuurman, Kyra E; Weiss, Marjan M; Shakeel, Hassan; Tee, Louise; Morgan, Neil V; Nikkels, Peter G J; van Haaften, Gijs; Park, Soo-Mi; van der Smagt, Jasper J; Bugiani, Marianna; Maher, Eamonn R
2014-12-05
Foetal akinesia deformation sequence syndrome (FADS) is a genetically heterogeneous disorder characterised by the combination of foetal akinesia and developmental defects which may include pterygia (joint webbing). Traditionally multiple pterygium syndrome (MPS) has been divided into two forms: prenatally lethal (LMPS) and non-lethal Escobar type (EVMPS) types. Interestingly, FADS, LMPS and EVMPS may be allelic e.g. each of these phenotypes may result from mutations in the foetal acetylcholine receptor gamma subunit gene (CHRNG). Many cases of FADS and MPS do not have a mutation in a known FADS/MPS gene and we undertook molecular genetic studies to identify novel causes of these phenotypes. After mapping a novel locus for FADS/LMPS to chromosome 19, we identified a homozygous null mutation in the RYR1 gene in a consanguineous kindred with recurrent LMPS pregnancies. Resequencing of RYR1 in a cohort of 66 unrelated probands with FADS/LMPS/EVMPS (36 with FADS/LMPS and 30 with EVMPS) revealed two additional homozygous mutations (in frame deletions). The overall frequency of RYR1 mutations in probands with FADS/LMPS was 8.3%. Our findings report, for the first time, a homozygous RYR1 null mutation and expand the range of RYR1-related phenotypes to include early lethal FADS/LMPS. We suggest that RYR1 mutation analysis should be performed in cases of severe FADS/LMPS even in the absence of specific histopathological indicators of RYR1-related disease.
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Tsutsui, Hiroki; Higashiyama, Tetsuya
2017-01-01
The CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated 9) system is widely used as a tool for genome engineering in various organisms. A complex consisting of Cas9 and single guide RNA (sgRNA) induces a DNA double-strand break in a sequence-specific manner, resulting in knockout. Some binary vectors for CRISPR/Cas9 in plants have been reported, but there is a problem with low efficiency. Here, we present a newly developed, highly efficient CRISPR/Cas9 vector for Arabidopsis thaliana, pKAMA-ITACHI Red (pKIR), harboring the RIBOSOMAL PROTEIN S5 A (RPS5A) promoter to drive Cas9. The RPS5A promoter maintains high constitutive expression at all developmental stages starting from the egg cell and including meristematic cells. Even in the T1 generation, pKIR induced null phenotypes in some genes: PHYTOENE DESATURASE 3 (PDS3), AGAMOUS (AG) and DUO POLLEN 1 (DUO1). Mutations induced by pKIR were carried in the germ cell line of the T1 generation. Surprisingly, in some lines, 100% of the T2 plants had the adh1 (ALCOHOL DEHYDROGENASE 1) null phenotype, indicating that pKIR strongly induced heritable mutations. Cas9-free T2 mutant plants were obtained by removing T2 seeds expressing a fluorescent marker in pKIR. Our results suggest that the pKIR system is a powerful molecular tool for genome engineering in Arabidopsis. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.
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Loss of virulence in Ustilago maydis by Umchs6 gene disruption.
Garcerá-Teruel, Ana; Xoconostle-Cázares, Beatriz; Rosas-Quijano, Raymundo; Ortiz, Lucila; León-Ramírez, Claudia; Specht, Charles A; Sentandreu, Rafael; Ruiz-Herrera, José
2004-03-01
A gene encoding a sixth chitin synthase (Umchs6, sequence GenBank accession No. ) from the plant pathogenic hemibasidiomycete Ustilago maydis (DC.) Cda. was isolated and characterized. The predicted protein is 1103 amino acids in length with a calculated molecular mass of 123.5 kDa. a2b2 null mutants were obtained by substitution of a central fragment of the Umchs6 gene with the hygromycin resistance cassette, and a1b1 null mutants were obtained by genetic recombination in plants of an a2b2deltach6 and a wild-type a1b1 strain. The mutation had no effect on the dimorphic transition in vitro or on mating, and growth rate of the mutants was only slightly reduced. On the other hand, they displayed important alterations in cell morphology, particularly at the mycelial stage, and in the staining pattern with calcofluor white. Levels of chitin synthase activity in vitro and chitin content were reduced. The most noticeable characteristic of the mutants was their almost complete loss of virulence to maize (Zea mays L.). This was a recessive character. Microscopic observations during the infectious process suggest that chitin synthase 6 activity is very important for growth of the fungus into the plant. Transformation of a2b2deltach6 mutants with an autonomous replicating plasmid carrying the full Umchs6 gene restored their normal morphological phenotype and virulence. These results are evidence that the mutation in the Umchs6 gene was solely responsible for the phenotypic alterations observed.
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Evolution of the human immunodeficiency virus envelope gene is dominated by purifying selection.
Edwards, C T T; Holmes, E C; Pybus, O G; Wilson, D J; Viscidi, R P; Abrams, E J; Phillips, R E; Drummond, A J
2006-11-01
The evolution of the human immunodeficiency virus (HIV-1) during chronic infection involves the rapid, continuous turnover of genetic diversity. However, the role of natural selection, relative to random genetic drift, in governing this process is unclear. We tested a stochastic model of genetic drift using partial envelope sequences sampled longitudinally in 28 infected children. In each case the Bayesian posterior (empirical) distribution of coalescent genealogies was estimated using Markov chain Monte Carlo methods. Posterior predictive simulation was then used to generate a null distribution of genealogies assuming neutrality, with the null and empirical distributions compared using four genealogy-based summary statistics sensitive to nonneutral evolution. Because both null and empirical distributions were generated within a coalescent framework, we were able to explicitly account for the confounding influence of demography. From the distribution of corrected P-values across patients, we conclude that empirical genealogies are more asymmetric than expected if evolution is driven by mutation and genetic drift only, with an excess of low-frequency polymorphisms in the population. This indicates that although drift may still play an important role, natural selection has a strong influence on the evolution of HIV-1 envelope. A negative relationship between effective population size and substitution rate indicates that as the efficacy of selection increases, a smaller proportion of mutations approach fixation in the population. This suggests the presence of deleterious mutations. We therefore conclude that intrahost HIV-1 evolution in envelope is dominated by purifying selection against low-frequency deleterious mutations that do not reach fixation.
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Genetic Rescue of Glycosylation-deficient Fgf23 in the Galnt3 Knockout Mouse
Gray, Amie K.; Padgett, Leah R.; Allen, Matthew R.; Clinkenbeard, Erica L.; Sarpa, Nicole M.; White, Kenneth E.; Econs, Michael J.
2014-01-01
Fibroblast growth factor 23 (FGF23) is a hormone that inhibits renal phosphate reabsorption and 1,25-dihydroxyvitamin D biosynthesis. The FGF23 subtilisin-like proprotein convertase recognition sequence (176RHTR179↓) is protected by O-glycosylation through ppGalNAc-T3 (GALNT3) activity. Thus, inactivating GALNT3 mutations render FGF23 susceptible to proteolysis, thereby reducing circulating intact hormone levels and leading to hyperphosphatemic familial tumoral calcinosis. To further delineate the role of glycosylation in the Fgf23 function, we generated an inducible FGF23 transgenic mouse expressing human mutant FGF23 (R176Q and R179Q) found in patients with autosomal dominant hypophosphatemic rickets (ADHR) and bred this animal to Galnt3 knockout mice, a model of familial tumoral calcinosis. Due to the low intact Fgf23 level, Galnt3 knockout mice with wild-type Fgf23 alleles were hyperphosphatemic. In contrast, carriers of the mutant FGF23 transgene, regardless of Galnt3 mutation status, had significantly higher serum intact FGF23, resulting in severe hypophosphatemia. Importantly, serum phosphorus and FGF23 were comparable between transgenic mice with or without normal Galnt3 alleles. To determine whether the presence of the ADHR mutation could improve biochemical and skeletal abnormalities in Galnt3-null mice, these mice were also mated to Fgf23 knock-in mice, carrying heterozygous or homozygous R176Q ADHR Fgf23 mutations. The knock-in mice with functional Galnt3 had normal Fgf23 but were slightly hypophosphatemic. The stabilized Fgf23 ADHR allele reversed the Galnt3-null phenotype and normalized total Fgf23, serum phosphorus, and bone Fgf23 mRNA. However, the skeletal phenotype was unaffected. In summary, these data demonstrate that O-glycosylation by ppGaINAc-T3 is only necessary for proper secretion of intact Fgf23 and, once secreted, does not affect Fgf23 function. Furthermore, the more stable Fgf23 ADHR mutant protein could normalize serum phosphorus in Galnt3 knockout mice. PMID:25051439
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Genetic rescue of glycosylation-deficient Fgf23 in the Galnt3 knockout mouse.
Ichikawa, Shoji; Gray, Amie K; Padgett, Leah R; Allen, Matthew R; Clinkenbeard, Erica L; Sarpa, Nicole M; White, Kenneth E; Econs, Michael J
2014-10-01
Fibroblast growth factor 23 (FGF23) is a hormone that inhibits renal phosphate reabsorption and 1,25-dihydroxyvitamin D biosynthesis. The FGF23 subtilisin-like proprotein convertase recognition sequence ((176)RHTR(179)↓) is protected by O-glycosylation through ppGalNAc-T3 (GALNT3) activity. Thus, inactivating GALNT3 mutations render FGF23 susceptible to proteolysis, thereby reducing circulating intact hormone levels and leading to hyperphosphatemic familial tumoral calcinosis. To further delineate the role of glycosylation in the Fgf23 function, we generated an inducible FGF23 transgenic mouse expressing human mutant FGF23 (R176Q and R179Q) found in patients with autosomal dominant hypophosphatemic rickets (ADHR) and bred this animal to Galnt3 knockout mice, a model of familial tumoral calcinosis. Due to the low intact Fgf23 level, Galnt3 knockout mice with wild-type Fgf23 alleles were hyperphosphatemic. In contrast, carriers of the mutant FGF23 transgene, regardless of Galnt3 mutation status, had significantly higher serum intact FGF23, resulting in severe hypophosphatemia. Importantly, serum phosphorus and FGF23 were comparable between transgenic mice with or without normal Galnt3 alleles. To determine whether the presence of the ADHR mutation could improve biochemical and skeletal abnormalities in Galnt3-null mice, these mice were also mated to Fgf23 knock-in mice, carrying heterozygous or homozygous R176Q ADHR Fgf23 mutations. The knock-in mice with functional Galnt3 had normal Fgf23 but were slightly hypophosphatemic. The stabilized Fgf23 ADHR allele reversed the Galnt3-null phenotype and normalized total Fgf23, serum phosphorus, and bone Fgf23 mRNA. However, the skeletal phenotype was unaffected. In summary, these data demonstrate that O-glycosylation by ppGaINAc-T3 is only necessary for proper secretion of intact Fgf23 and, once secreted, does not affect Fgf23 function. Furthermore, the more stable Fgf23 ADHR mutant protein could normalize serum phosphorus in Galnt3 knockout mice.
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Scharner, J; Figeac, N; Ellis, J A; Zammit, P S
2015-06-01
Exon skipping, as a therapy to restore a reading frame or switch protein isoforms, is under clinical trial. We hypothesised that removing an in-frame exon containing a mutation could also improve pathogenic phenotypes. Our model is laminopathies: incurable tissue-specific degenerative diseases associated with LMNA mutations. LMNA encodes A-type lamins, that together with B-type lamins, form the nuclear lamina. Lamins contain an alpha-helical central rod domain composed of multiple heptad repeats. Eliminating LMNA exon 3 or 5 removes six heptad repeats, so shortens, but should not otherwise significantly alter, the alpha-helix. Human Lamin A or Lamin C with a deletion corresponding to amino acids encoded by exon 5 (Lamin A/C-Δ5) localised normally in murine lmna-null cells, rescuing both nuclear shape and endogenous Lamin B1/emerin distribution. However, Lamin A carrying pathogenic mutations in exon 3 or 5, or Lamin A/C-Δ3, did not. Furthermore, Lamin A/C-Δ5 was not deleterious to wild-type cells, unlike the other Lamin A mutants including Lamin A/C-Δ3. Thus Lamin A/C-Δ5 function as effectively as wild-type Lamin A/C and better than mutant versions. Antisense oligonucleotides skipped LMNA exon 5 in human cells, demonstrating the possibility of treating certain laminopathies with this approach. This proof-of-concept is the first to report the therapeutic potential of exon skipping for diseases arising from missense mutations.
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Schmid, Martin R.; Anderl, Ines; Vo, Hoa T. M.; Valanne, Susanna; Yang, Hairu; Kronhamn, Jesper; Rämet, Mika; Rusten, Tor Erik
2016-01-01
To understand how Toll signaling controls the activation of a cellular immune response in Drosophila blood cells (hemocytes), we carried out a genetic modifier screen, looking for deletions that suppress or enhance the mobilization of sessile hemocytes by the gain-of-function mutation Toll10b (Tl10b). Here we describe the results from chromosome arm 3R, where five regions strongly suppressed this phenotype. We identified the specific genes immune response deficient 1 (ird1), headcase (hdc) and possibly Rab23 as suppressors, and we studied the role of ird1 in more detail. An ird1 null mutant and a mutant that truncates the N-terminal kinase domain of the encoded Ird1 protein affected the Tl10b phenotype, unlike mutations that affect the C-terminal part of the protein. The ird1 null mutant suppressed mobilization of sessile hemocytes, but enhanced other Tl10b hemocyte phenotypes, like the formation of melanotic nodules and the increased number of circulating hemocytes. ird1 mutants also had blood cell phenotypes on their own. They lacked crystal cells and showed aberrant formation of lamellocytes. ird1 mutant plasmatocytes had a reduced ability to spread on an artificial substrate by forming protrusions, which may explain why they did not go into circulation in response to Toll signaling. The effect of the ird1 mutation depended mainly on ird1 expression in hemocytes, but ird1-dependent effects in other tissues may contribute. Specifically, the Toll receptor was translocated from the cell membrane to intracellular vesicles in the fat body of the ird1 mutant, and Toll signaling was activated in that tissue, partially explaining the Tl10b-like phenotype. As ird1 is otherwise known to control vesicular transport, we conclude that the vesicular transport system may be of particular importance during an immune response. PMID:27467079
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Suzuki, Emiko; Saga, Yumiko
2017-01-01
The segmental pattern of the vertebrate body is established via the periodic formation of somites from the presomitic mesoderm (PSM). This periodical process is controlled by the cyclic and synchronized activation of Notch signaling in the PSM. Protein O-fucosyltransferase1 (Pofut1), which transfers O-fucose to the EGF domains of the Notch1 receptor, is indispensable for Notch signaling activation. The Drosophila homologue Ofut1 was reported to control Notch localization via two different mechanisms, working as a chaperone for Notch or as a regulator of Notch endocytosis. However, these were found to be independent of O-fucosyltransferase activity because the phenotypes were rescued by Ofut1 mutants lacking O-fucosyltransferase activity. Pofut1 may also be involved in the Notch receptor localization in mice. However, the contribution of enzymatic activity of Pofut1 to the Notch receptor dynamics remains to be elucidated. In order to clarify the importance of the O-fucosyltransferase activity of Pofut1 for Notch signaling activation and the protein localization in the PSM, we established mice carrying point mutations at the 245th a.a. or 370-372th a.a., highly conserved amino-acid sequences whose mutations disrupt the O-fucosyltransferase activity of both Drosophila Ofut1 and mammalian Pofut1, with the CRISPR/Cas9 mediated genome-engineering technique. Both mutants displayed the same severely perturbed somite formation and Notch1 subcellular localization defects as the Pofut1 null mutants. In the mutants, Pofut1 protein, but not RNA, became undetectable by E9.5. Furthermore, both wild-type and mutant Pofut1 proteins were degraded through lysosome dependent machinery. Pofut1 protein loss in the point mutant embryos caused the same phenotypes as those observed in Pofut1 null embryos. PMID:29095923
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Sajedi, Ezat; Gaston-Massuet, Carles; Signore, Massimo; Andoniadou, Cynthia L.; Kelberman, Daniel; Castro, Sandra; Etchevers, Heather C.; Gerrelli, Dianne; Dattani, Mehul T.; Martinez-Barbera, Juan Pedro
2008-01-01
SUMMARY A homozygous substitution of the highly conserved isoleucine at position 26 by threonine (I26T) in the transcriptional repressor HESX1 has been associated with anterior pituitary hypoplasia in a human patient, with no forebrain or eye defects. Two individuals carrying a homozygous substitution of the conserved arginine at position 160 by cysteine (R160C) manifest septo-optic dysplasia (SOD), a condition characterised by pituitary abnormalities associated with midline telencephalic structure defects and optic nerve hypoplasia. We have generated two knock-in mouse models containing either the I26T or R160C substitution in the genomic locus. Hesx1I26T/I26T embryos show pituitary defects comparable with Hesx1−/− mouse mutants, with frequent occurrence of ocular abnormalities, although the telencephalon develops normally. Hesx1R160C/R160C mutants display forebrain and pituitary defects that are identical to those observed in Hesx1−/− null mice. We also show that the expression pattern of HESX1 during early human development is very similar to that described in the mouse, suggesting that the function of HESX1 is conserved between the two species. Together, these results suggest that the I26T mutation yields a hypomorphic allele, whereas R160C produces a null allele and, consequently, a more severe phenotype in both mice and humans. PMID:19093031
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Garçon, Loïc; Ge, Jingping; Manjunath, Shwetha H.; Mills, Jason A.; Apicella, Marisa; Parikh, Shefali; Sullivan, Lisa M.; Podsakoff, Gregory M.; Gadue, Paul; French, Deborah L.; Mason, Philip J.; Bessler, Monica
2013-01-01
Diamond Blackfan anemia (DBA) is a congenital disorder with erythroid (Ery) hypoplasia and tissue morphogenic abnormalities. Most DBA cases are caused by heterozygous null mutations in genes encoding ribosomal proteins. Understanding how haploinsufficiency of these ubiquitous proteins causes DBA is hampered by limited availability of tissues from affected patients. We generated induced pluripotent stem cells (iPSCs) from fibroblasts of DBA patients carrying mutations in RPS19 and RPL5. Compared with controls, DBA fibroblasts formed iPSCs inefficiently, although we obtained 1 stable clone from each fibroblast line. RPS19-mutated iPSCs exhibited defects in 40S (small) ribosomal subunit assembly and production of 18S ribosomal RNA (rRNA). Upon induced differentiation, the mutant clone exhibited globally impaired hematopoiesis, with the Ery lineage affected most profoundly. RPL5-mutated iPSCs exhibited defective 60S (large) ribosomal subunit assembly, accumulation of 12S pre-rRNA, and impaired erythropoiesis. In both mutant iPSC lines, genetic correction of ribosomal protein deficiency via complementary DNA transfer into the “safe harbor” AAVS1 locus alleviated abnormalities in ribosome biogenesis and hematopoiesis. Our studies show that pathological features of DBA are recapitulated by iPSCs, provide a renewable source of cells to model various tissue defects, and demonstrate proof of principle for genetic correction strategies in patient stem cells. PMID:23744582
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Garçon, Loïc; Ge, Jingping; Manjunath, Shwetha H; Mills, Jason A; Apicella, Marisa; Parikh, Shefali; Sullivan, Lisa M; Podsakoff, Gregory M; Gadue, Paul; French, Deborah L; Mason, Philip J; Bessler, Monica; Weiss, Mitchell J
2013-08-08
Diamond Blackfan anemia (DBA) is a congenital disorder with erythroid (Ery) hypoplasia and tissue morphogenic abnormalities. Most DBA cases are caused by heterozygous null mutations in genes encoding ribosomal proteins. Understanding how haploinsufficiency of these ubiquitous proteins causes DBA is hampered by limited availability of tissues from affected patients. We generated induced pluripotent stem cells (iPSCs) from fibroblasts of DBA patients carrying mutations in RPS19 and RPL5. Compared with controls, DBA fibroblasts formed iPSCs inefficiently, although we obtained 1 stable clone from each fibroblast line. RPS19-mutated iPSCs exhibited defects in 40S (small) ribosomal subunit assembly and production of 18S ribosomal RNA (rRNA). Upon induced differentiation, the mutant clone exhibited globally impaired hematopoiesis, with the Ery lineage affected most profoundly. RPL5-mutated iPSCs exhibited defective 60S (large) ribosomal subunit assembly, accumulation of 12S pre-rRNA, and impaired erythropoiesis. In both mutant iPSC lines, genetic correction of ribosomal protein deficiency via complementary DNA transfer into the "safe harbor" AAVS1 locus alleviated abnormalities in ribosome biogenesis and hematopoiesis. Our studies show that pathological features of DBA are recapitulated by iPSCs, provide a renewable source of cells to model various tissue defects, and demonstrate proof of principle for genetic correction strategies in patient stem cells.
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Divergence of IL-1, IL-18, and cell death in NLRP3 inflammasomopathies
Brydges, Susannah D.; Broderick, Lori; McGeough, Matthew D.; Pena, Carla A.; Mueller, James L.; Hoffman, Hal M.
2013-01-01
The inflammasome is a cytoplasmic multiprotein complex that promotes proinflammatory cytokine maturation in response to host- and pathogen-derived signals. Missense mutations in cryopyrin (NLRP3) result in a hyperactive inflammasome that drives overproduction of the proinflammatory cytokines IL-1β and IL-18, leading to the cryopyrin-associated periodic syndromes (CAPS) disease spectrum. Mouse lines harboring CAPS-associated mutations in Nlrp3 have elevated levels of IL-1β and IL-18 and closely mimic human disease. To examine the role of inflammasome-driven IL-18 in murine CAPS, we bred Nlrp3 mutations onto an Il18r-null background. Deletion of Il18r resulted in partial phenotypic rescue that abolished skin and visceral disease in young mice and normalized serum cytokines to a greater extent than breeding to Il1r-null mice. Significant systemic inflammation developed in aging Nlrp3 mutant Il18r-null mice, indicating that IL-1 and IL-18 drive pathology at different stages of the disease process. Ongoing inflammation in double-cytokine knockout CAPS mice implicated a role for caspase-1–mediated pyroptosis and confirmed that CAPS is inflammasome dependent. Our results have important implications for patients with CAPS and residual disease, emphasizing the need to explore other NLRP3-mediated pathways and the potential for inflammasome-targeted therapy. PMID:24084736
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Reassessment of murine APOBEC1 as a retrovirus restriction factor in vivo.
Barrett, Bradley S; Guo, Kejun; Harper, Michael S; Li, Sam X; Heilman, Karl J; Davidson, Nicholas O; Santiago, Mario L
2014-11-01
APOBEC1 is a cytidine deaminase involved in cholesterol metabolism that has been linked to retrovirus restriction, analogous to the evolutionarily-related APOBEC3 proteins. In particular, murine APOBEC1 was shown to inhibit Friend retrovirus (FV) in vitro, generating high levels of C-to-T and G-to-A mutations. These observations raised the possibility that FV infection might be altered in APOBEC1-null mice. To examine this question directly, we infected wild-type and APOBEC1-null mice with FV complex and evaluated acute infection levels. Surprisingly, APOBEC1-null mice exhibited similar cellular infection levels and plasma viremia relative to wild-type mice. Moreover, next-generation sequencing analyses revealed that in contrast to APOBEC3, APOBEC1 did not enhance retroviral C-to-T and G-to-A mutational frequencies in genomic DNA. Thus, APOBEC1 neither inhibited nor significantly drove the molecular evolution of FV in vivo. Our findings reinforce that not all retrovirus restriction factors characterized as potent in vitro may be functionally relevant in vivo. Copyright © 2014 Elsevier Inc. All rights reserved.
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Cao, Ou; Hoffman, Brad E; Moghimi, Babak; Nayak, Sushrusha; Cooper, Mario; Zhou, Shangzhen; Ertl, Hildegund C J; High, Katherine A; Herzog, Roland W
2009-10-01
Immune responses to factor IX (F.IX), a major concern in gene therapy for hemophilia, were analyzed for adeno-associated viral (AAV-2) gene transfer to skeletal muscle and liver as a function of the F9 underlying mutation. Vectors identical to those recently used in clinical trials were administered to four lines of hemophilia B mice on a defined genetic background [C3H/HeJ with deletion of endogenous F9 and transgenic for a range of nonfunctional human F.IX (hF.IX) variants]. The strength of the immune response to AAV-encoded F.IX inversely correlated with the degree of conservation of endogenous coding information and levels of endogenous antigen. Null mutation animals developed T- and B-cell responses in both protocols. However, inhibitor titers were considerably higher upon muscle gene transfer (or protein therapy). Transduced muscles of Null mice had strong infiltrates with CD8+ cells, which were much more limited in the liver and not seen for the other mutations. Sustained expression was achieved with liver transduction in mice with crm(-) nonsense and missense mutations, although they still formed antibodies upon muscle gene transfer. Therefore, endogenous expression prevented T-cell responses more effectively than antibody formation, and immune responses varied substantially depending on the protocol and the underlying mutation.
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Osteogenesis imperfecta type I: Molecular heterogeneity for COL1A1 null alleles of type I collagen
DOE Office of Scientific and Technical Information (OSTI.GOV)
Willing, M.C.; Deschenes, S.P.; Pitts, S.H.
Osteogenesis imperfecta (OI) type I is the mildest form of inherited brittle-bone disease. Dermal fibroblasts from most affected individuals produce about half the usual amount of type I procollagen, as a result of a COL1A1 {open_quotes}null{close_quotes} allele. Using PCR amplification of genomic DNA from affected individuals, followed by denaturing gradient gel electrophoresis (DGGE) and SSCP, we identified seven different COL1A1 gene mutations in eight unrelated families with OI type I. Three families have single nucleotide substitutions that alter 5{prime} donor splice sites; two of these unrelated families have the same mutation. One family has a point mutation, in an exon,more » that creates a premature termination codon, and four have small deletions or insertions, within exons, that create translational frameshifts and new termination codons downstream of the mutation sites. Each mutation leads to both marked reduction in steady-state levels of mRNA from the mutant allele and a quantitative decrease in type I procollagen production. Our data demonstrate that different molecular mechanisms that have the same effect on type I collagen production result in the same clinical phenotype. 58 refs., 4 figs., 1 tab.« less
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Falik-Zaccai, Tzipora C; Erel-Segal, Reut; Horev, Liran; Bitterman-Deutsch, Ora; Koka, Sivan; Chaim, Sara; Keren, Zohar; Kalfon, Limor; Gross, Bella; Segal, Zvi; Orgal, Shlomi; Shoval, Yishay; Slor, Hanoch; Spivak, Graciela; Hanawalt, Philip C
2012-08-01
The XPD protein plays a pivotal role in basal transcription and in nucleotide excision repair (NER) as one of the ten known components of the transcription factor TFIIH. Mutations in XPD can result in the DNA repair-deficient diseases xeroderma pigmentosum (XP), trichothiodystrophy (TTD), cerebro-oculo-facial-skeletal syndrome, and in combined phenotypes such as XP/Cockayne syndrome and XP/TTD. We describe here an 18-year-old individual with mild sun sensitivity, no neurological abnormalities and no tumors, who carries a p.R683Q mutation in one allele, and the novel p.R616Q mutation in the other allele of the XPD gene. We also describe four patients from one family, homozygous for the identical p.R683Q mutation in XPD, who exhibit mild skin pigmentation and loss of tendon reflexes. Three homozygous patients presented with late-onset skin tumors, and two with features of premature aging and moderate cognitive decline. Cells from the compound heterozygous individual and from one of the patients homozygous for p.R683Q exhibited similar responses to UV irradiation: reduced viability and defective overall removal of UV-induced cyclobutane pyrimidine dimers, implying deficient global genomic NER. Cells from the compound heterozygous subject also failed to recover RNA synthesis after UV, indicating defective transcription-coupled NER. Mutations affecting codon 616 in XPD generally result in functionally null proteins; we hypothesize that the phenotype of the heterozygous patient results solely from expression of the p.R683Q allele. This study illustrates the importance of detailed follow up with sun sensitive individuals, to ensure appropriate prophylaxis and to understand the mechanistic basis of the implicated hereditary disease. Copyright © 2012 Wiley Periodicals, Inc.
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A site specific model and analysis of the neutral somatic mutation rate in whole-genome cancer data.
Bertl, Johanna; Guo, Qianyun; Juul, Malene; Besenbacher, Søren; Nielsen, Morten Muhlig; Hornshøj, Henrik; Pedersen, Jakob Skou; Hobolth, Asger
2018-04-19
Detailed modelling of the neutral mutational process in cancer cells is crucial for identifying driver mutations and understanding the mutational mechanisms that act during cancer development. The neutral mutational process is very complex: whole-genome analyses have revealed that the mutation rate differs between cancer types, between patients and along the genome depending on the genetic and epigenetic context. Therefore, methods that predict the number of different types of mutations in regions or specific genomic elements must consider local genomic explanatory variables. A major drawback of most methods is the need to average the explanatory variables across the entire region or genomic element. This procedure is particularly problematic if the explanatory variable varies dramatically in the element under consideration. To take into account the fine scale of the explanatory variables, we model the probabilities of different types of mutations for each position in the genome by multinomial logistic regression. We analyse 505 cancer genomes from 14 different cancer types and compare the performance in predicting mutation rate for both regional based models and site-specific models. We show that for 1000 randomly selected genomic positions, the site-specific model predicts the mutation rate much better than regional based models. We use a forward selection procedure to identify the most important explanatory variables. The procedure identifies site-specific conservation (phyloP), replication timing, and expression level as the best predictors for the mutation rate. Finally, our model confirms and quantifies certain well-known mutational signatures. We find that our site-specific multinomial regression model outperforms the regional based models. The possibility of including genomic variables on different scales and patient specific variables makes it a versatile framework for studying different mutational mechanisms. Our model can serve as the neutral null model for the mutational process; regions that deviate from the null model are candidates for elements that drive cancer development.
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Expression and function of FGF10 in mammalian inner ear development
NASA Technical Reports Server (NTRS)
Pauley, Sarah; Wright, Tracy J.; Pirvola, Ulla; Ornitz, David; Beisel, Kirk; Fritzsch, Bernd
2003-01-01
We have investigated the expression of FGF10 during ear development and the effect of an FGF10 null mutation on ear development. Our in situ hybridization data reveal expression of FGF10 in all three canal crista sensory epithelia and the cochlea anlage as well as all sensory neurons at embryonic day 11.5 (E11.5). Older embryos (E18.5) displayed strong graded expression in all sensory epithelia. FGF10 null mutants show complete agenesis of the posterior canal crista and the posterior canal. The posterior canal sensory neurons form initially and project rather normally by E11.5, but they disappear within 2 days. FGF10 null mutants have no posterior canal system at E18.5. In addition, these mutants have deformations of the anterior and horizontal cristae, reduced formation of the anterior and horizontal canals, as well as altered position of the remaining sensory epithelia with respect to the utricle. Hair cells form but some have defects in their cilia formation. No defects were detected in the organ of Corti at the cellular level. Together these data suggest that FGF10 plays a major role in ear morphogenesis. Most of these data are consistent with earlier findings on a null mutation in FGFR2b, one of FGF10's main receptors. Copyright 2003 Wiley-Liss, Inc.
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Exome sequencing identifies rare LDLR and APOA5 alleles conferring risk for myocardial infarction.
Do, Ron; Stitziel, Nathan O; Won, Hong-Hee; Jørgensen, Anders Berg; Duga, Stefano; Angelica Merlini, Pier; Kiezun, Adam; Farrall, Martin; Goel, Anuj; Zuk, Or; Guella, Illaria; Asselta, Rosanna; Lange, Leslie A; Peloso, Gina M; Auer, Paul L; Girelli, Domenico; Martinelli, Nicola; Farlow, Deborah N; DePristo, Mark A; Roberts, Robert; Stewart, Alexander F R; Saleheen, Danish; Danesh, John; Epstein, Stephen E; Sivapalaratnam, Suthesh; Hovingh, G Kees; Kastelein, John J; Samani, Nilesh J; Schunkert, Heribert; Erdmann, Jeanette; Shah, Svati H; Kraus, William E; Davies, Robert; Nikpay, Majid; Johansen, Christopher T; Wang, Jian; Hegele, Robert A; Hechter, Eliana; Marz, Winfried; Kleber, Marcus E; Huang, Jie; Johnson, Andrew D; Li, Mingyao; Burke, Greg L; Gross, Myron; Liu, Yongmei; Assimes, Themistocles L; Heiss, Gerardo; Lange, Ethan M; Folsom, Aaron R; Taylor, Herman A; Olivieri, Oliviero; Hamsten, Anders; Clarke, Robert; Reilly, Dermot F; Yin, Wu; Rivas, Manuel A; Donnelly, Peter; Rossouw, Jacques E; Psaty, Bruce M; Herrington, David M; Wilson, James G; Rich, Stephen S; Bamshad, Michael J; Tracy, Russell P; Cupples, L Adrienne; Rader, Daniel J; Reilly, Muredach P; Spertus, John A; Cresci, Sharon; Hartiala, Jaana; Tang, W H Wilson; Hazen, Stanley L; Allayee, Hooman; Reiner, Alex P; Carlson, Christopher S; Kooperberg, Charles; Jackson, Rebecca D; Boerwinkle, Eric; Lander, Eric S; Schwartz, Stephen M; Siscovick, David S; McPherson, Ruth; Tybjaerg-Hansen, Anne; Abecasis, Goncalo R; Watkins, Hugh; Nickerson, Deborah A; Ardissino, Diego; Sunyaev, Shamil R; O'Donnell, Christopher J; Altshuler, David; Gabriel, Stacey; Kathiresan, Sekar
2015-02-05
Myocardial infarction (MI), a leading cause of death around the world, displays a complex pattern of inheritance. When MI occurs early in life, genetic inheritance is a major component to risk. Previously, rare mutations in low-density lipoprotein (LDL) genes have been shown to contribute to MI risk in individual families, whereas common variants at more than 45 loci have been associated with MI risk in the population. Here we evaluate how rare mutations contribute to early-onset MI risk in the population. We sequenced the protein-coding regions of 9,793 genomes from patients with MI at an early age (≤50 years in males and ≤60 years in females) along with MI-free controls. We identified two genes in which rare coding-sequence mutations were more frequent in MI cases versus controls at exome-wide significance. At low-density lipoprotein receptor (LDLR), carriers of rare non-synonymous mutations were at 4.2-fold increased risk for MI; carriers of null alleles at LDLR were at even higher risk (13-fold difference). Approximately 2% of early MI cases harbour a rare, damaging mutation in LDLR; this estimate is similar to one made more than 40 years ago using an analysis of total cholesterol. Among controls, about 1 in 217 carried an LDLR coding-sequence mutation and had plasma LDL cholesterol > 190 mg dl(-1). At apolipoprotein A-V (APOA5), carriers of rare non-synonymous mutations were at 2.2-fold increased risk for MI. When compared with non-carriers, LDLR mutation carriers had higher plasma LDL cholesterol, whereas APOA5 mutation carriers had higher plasma triglycerides. Recent evidence has connected MI risk with coding-sequence mutations at two genes functionally related to APOA5, namely lipoprotein lipase and apolipoprotein C-III (refs 18, 19). Combined, these observations suggest that, as well as LDL cholesterol, disordered metabolism of triglyceride-rich lipoproteins contributes to MI risk.
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Frequencies of Null Alleles at Enzyme Loci in Natural Populations of Ponderosa and Red Pine
Allendorf, Fred W.; Knudsen, Kathy L.; Blake, George M.
1982-01-01
Pinus ponderosa and P. resinosa population samples have mean frequencies of enzymatically inactive alleles of 0.0031 and 0.0028 at 29 and 27 enzyme loci, respectively. Such alleles are rare and are apparently maintained by selection-mutation balance. Ponderosa pine have much higher amounts of allozymic and polygenic phenotypic variation than red pine, yet both species have similar frequencies of null alleles. Thus, null alleles apparently do not contribute to polygenic variation, as has been suggested. The concordance between allozymic and polygenic variation adds support to the view that allozyme studies may be valuable in predicting the relative amount of polygenic variation in populations. PMID:17246067
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Liu, Fang; Jiao, An-xia; Wu, Xi-rong; Zhao, Wei; Yin, Qing-qin; Qi, Hui; Jiao, Wei-wei; Xiao, Jing; Sun, Lin; Shen, Chen; Tian, Jian-ling; Shen, Dan; Jacqz-Aigrain, Evelyne; Shen, A-dong
2014-01-01
Anti-tuberculosis drug induced hepatotoxicity (ATDH) is a major adverse drug reaction associated for anti-tuberculosis therapy. The glutathione S-transferases (GST) plays a crucial role in the detoxification of hepatotoxic metabolites of anti-tuberculosis drugs.An association between GSTM1/GSTT1 null mutations and increased risk of ATDH has been demonstrated in adults. Given the ethnic differences and developmental changes, our study aims to investigate the potential impacts of GSTM1/GSTT1 genotypes on the development of ATDH in Han Chinese children treated with anti-tuberculosis therapy. Children receiving anti-tuberculosis therapy with or without evidence of ATDH were considered as the cases or controls, respectively. The GSTM1 and GSTT1 genotyping were performed using the polymerase chain reaction. One hundred sixty-three children (20 cases and 143 controls) with a mean age of 4.7 years (range: 2 months-14.1 years) were included. For the GSTM1, 14 (70.0%) cases and 96 (67.1%) controls had homozygous null mutations. For the GSTT1, 13 (65.0%) cases and 97 (67.8%) controls had homozygous null mutations. Neither the GSTM1, nor the GSTT1 polymorphism was significantly correlated with the occurrence of ATHD. Our results did not support the GSTM1 and GSTT1 polymorphisms as the predictors of ADTH in Chinese Han children treated with anti-tuberculosis drugs. An age-related association between pharmacogenetics and ATHD need to be confirmed in the further study.
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Renvoisé, Benoît; Malone, Brianna; Falgairolle, Melanie; Munasinghe, Jeeva; Stadler, Julia; Sibilla, Caroline; Park, Seong H; Blackstone, Craig
2016-12-01
Hereditary spastic paraplegias (HSPs; SPG1-76 plus others) are length-dependent disorders affecting long corticospinal axons, and the most common autosomal dominant forms are caused by mutations in genes that encode the spastin (SPG4), atlastin-1 (SPG3A) and REEP1 (SPG31) proteins. These proteins bind one another and shape the tubular endoplasmic reticulum (ER) network throughout cells. They also are involved in lipid droplet formation, enlargement, or both in cells, though mechanisms remain unclear. Here we have identified evidence of partial lipoatrophy in Reep1 null mice in addition to prominent spastic paraparesis. Furthermore, Reep1-/- embryonic fibroblasts and neurons in the cerebral cortex both show lipid droplet abnormalities. The apparent partial lipodystrophy in Reep1 null mice, although less severe, is reminiscent of the lipoatrophy phenotype observed in the most common form of autosomal recessive lipodystrophy, Berardinelli-Seip congenital lipodystrophy. Berardinelli-Seip lipodystrophy is caused by autosomal recessive mutations in the BSCL2 gene that encodes an ER protein, seipin, that is also mutated in the autosomal dominant HSP SPG17 (Silver syndrome). Furthermore, REEP1 co-immunoprecipitates with seipin in cells. This strengthens the link between alterations in ER morphogenesis and lipid abnormalities, with important pathogenic implications for the most common forms of HSP. Published by Oxford University Press 2016. This work is written by US Government employees and is in the public domain in the US.
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Manuylov, Nikolay L.; Fujiwara, Yuko; Adameyko, Igor I.; Poulat, Francis
2007-01-01
We have previously established an in vivo requirement for GATA4 and FOG2 transcription factors in sexual differentiation. Fog2 null mouse fetuses or fetuses homozygous for a targeted mutation in Gata4 (Gata4ki), which cripples the GATA4-FOG2 interaction, exhibit a profound and early block in testis differentiation in both sexes. Others have shown that XX mice with the Ods transgenic insertion or the Wt1-Sox9 YAC transgene overexpress the testis differentiation gene, Sox9. Thus, these XX animals undergo dominant sex-reversal by developing into phenotypically normal, but sterile, males. Now we have determined that Fog2 haploinsufficiency prevents (suppresses) this dominant sex-reversal and Fog2+/− Wt1-Sox9 or Ods XX animals develop normally - as fertile females. The suppression of sex-reversal in Fog2 heterozygous females results from approximately 50% downregulation of the expression from the transgene-associated allele of Sox9. The GATA4/FOG2-dependent sex reversal observed in the transgenic XX gonads has to rely on gene targets other than the Y chromosome-linked Sry gene. Importantly, Fog2 null or Gata4ki/ki embryos (either XX or XY) fail to express detectable levels of Sox9 despite carrying the Ods mutation or Wt1-Sox9 transgene. Fog2 haploinsufficiency leads to a decreased amount of SOX9-positive cells in XY gonads. We conclude that FOG2 is a limiting factor in the formation of a functional GATA4/FOG2 transcription complex that is required for Sox9 expression during gonadogenesis. PMID:17540364
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Paloma, E; Martínez-Mir, A; Vilageliu, L; Gonzàlez-Duarte, R; Balcells, S
2001-06-01
The ABCA4 gene has been involved in several forms of inherited macular dystrophy. In order to further characterize the complex genotype-phenotype relationships involving this gene, we have performed a mutation analysis of ABCA4 in 14 Spanish patients comprising eight STGD (Stargardt), four FFM (fundus flavimaculatus), and two CRD (Cone-rod dystrophy) patients. SSCP (single-strand conformation polymorphism) analysis and DNA sequencing of the coding and 5' upstream regions of this gene allowed the identification of 16 putatively pathogenic alterations, nine of which are novel. Most of these were missense changes, and no patient was found to carry two null alleles. Overall, the new data agree with a working model relating the different pathogenic phenotypes to the severity of the mutations. When considering the information presented here together with that of previous reports, a picture of the geographic distribution of three particular mutations emerges. The R212C change has been found in French, Italian, Dutch, German, and Spanish but not in British patients. In the Spanish collection, R212C was found in a CRD patient, indicating that it may be a rather severe change. In contrast, c.2588G>C, a very common mild allele in the Dutch population, is rarely found in Southern Europe. Interestingly, the c.2588G>C mutation has been found in a double mutant allele together with the missense R1055W. Finally, the newly described L1940P was found in two unrelated Spanish patients, and may be a moderate to severe allele. Copyright 2001 Wiley-Liss, Inc.
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Serreze, D V; Leiter, E H; Hanson, M S; Christianson, S W; Shultz, L D; Hesselton, R M; Greiner, D L
1995-12-01
When used as hosts in passive transfer experiments, a stock of NOD/Lt mice congenic for the severe combined immunodeficiency (scid) mutation have provided great insight to the contributions of various T-cell populations in the pathogenesis of autoimmune insulin-dependent diabetes mellitus (IDDM). Moreover, NOD-scid mice support higher levels of human lymphohematopoietic cell growth than the C.B-17-scid strain in which the mutation originated. However, the ability to perform long-term lymphohematopoietic repopulation studies in the NOD-scid stock has been limited by the fact that most of these mice develop lethal thymic lymphomas beginning at 20 weeks of age. These thymic lymphomas are characterized by activation and subsequent genomic reintegrations of Emv30, an endogenous murine ecotropic retrovirus unique to the NOD genome. To test the role of this endogenous retrovirus in thymomagenesis, we produced a stock of Emv30null NOD-scid mice by congenic replacement of the proximal end of chromosome 11 with genetic material derived from the closely related NOR/Lt strain. Thymic lymphomas still initiate in Emv30null NOD-scid females, but their rate of progression is significantly retarded since the frequency of tumors weighing between 170 and 910 mg at 25 weeks of age was reduced to 20.8% vs. 76.2% in Emv30% segregants. The thymic lymphomas that did develop in Emv30null NOD-scid mice were not characterized by a compensatory increase in mink cell focus-forming proviral integrations, which initiate thymomagenesis in other susceptible mouse strains. Significantly, the ability of standard NOD T-cells to transfer IDDM to the Emv30null NOD-scid stock was not impaired.(ABSTRACT TRUNCATED AT 250 WORDS)
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Four novel cases of periaxin-related neuropathy and review of the literature.
Marchesi, C; Milani, M; Morbin, M; Cesani, M; Lauria, G; Scaioli, V; Piccolo, G; Fabrizi, G M; Cavallaro, T; Taroni, F; Pareyson, D
2010-11-16
To report 4 cases of autosomal recessive hereditary neuropathy associated with novel mutations in the periaxin gene (PRX) with a review of the literature. Periaxin protein is required for the maintenance of peripheral nerve myelin. Patients with PRX mutations have early-onset autosomal recessive demyelinating Charcot-Marie-Tooth disease (CMT4F) or Déjèrine-Sottas neuropathy (DSN). Only 12 different mutations have been described thus far. Case reports and literature review. Four patients from 3 unrelated families (2 siblings and 2 unrelated patients) were affected by an early-onset, slowly progressive demyelinating neuropathy with relevant sensory involvement. All carried novel frameshift or nonsense mutations in the PRX gene. The 2 siblings were compound heterozygotes for 2 PRX null mutations (p.Q547X and p.K808SfsX2), the third patient harbored a homozygous nonsense mutation (p.E682X), and the last patient had a homozygous 2-nt insertion predicting a premature protein truncation (p.S259PfsX55). Electrophysiologic analysis showed a severe slowing of motor nerve conduction velocities (MNCVs, between 3 and 15.3 m/s) with undetectable sensory nerve action potentials (SNAPs). Sural nerve biopsy, performed in 2 patients, demonstrated a severe demyelinating neuropathy and onion bulb formations. Interestingly, we observed some variability of disease severity within the same family. These cases and review of the literature indicate that PRX-related neuropathies have early onset but overall slow progression. Typical features are prominent sensory involvement, often with sensory ataxia; a moderate-to-dramatic reduction of MNCVs and almost invariable absence of SNAPs; and pathologic demyelination with classic onion bulbs, and less commonly myelin folding and basal lamina onion bulbs.
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OPTN 691_692insAG is a founder mutation causing recessive ALS and increased risk in heterozygotes
Goldstein, Orly; Nayshool, Omri; Nefussy, Beatrice; Traynor, Bryan J.; Renton, Alan E.; Gana-Weisz, Mali; Drory, Vivian E.
2016-01-01
Objective: To detect genetic variants underlying familial and sporadic amyotrophic lateral sclerosis (ALS). Methods: We analyzed 2 founder Jewish populations of Moroccan and Ashkenazi origins and ethnic matched controls. Exome sequencing of 2 sisters with ALS from Morocco was followed by genotyping the identified causative null mutation in 379 unrelated patients with ALS and 1,000 controls. The shared risk haplotype was characterized using whole-genome single nucleotide polymorphism array. Results: We identified 5 unrelated patients with ALS homozygous for the null 691_692insAG mutation in the optineurin gene (OPTN), accounting for 5.8% of ALS of Moroccan origin and 0.3% of Ashkenazi. We also identified a high frequency of heterozygous carriers among patients with ALS, 8.7% and 2.9%, respectively, compared to 0.75% and 1.0% in controls. The risk of carriers for ALS was significantly increased, with odds ratio of 13.46 and 2.97 in Moroccan and Ashkenazi Jews, respectively. We determined that 691_692insAG is a founder mutation in the tested populations with a minimal risk haplotype of 58.5 Kb, encompassing the entire OPTN gene. Conclusions: Our data show that OPTN 691_692insAG mutation is a founder mutation in Moroccan and Ashkenazi Jews. This mutation causes autosomal recessive ALS and significantly increases the risk to develop the disease in heterozygous carriers, suggesting both a recessive mode of inheritance and a dominant with incomplete penetrance. These data emphasize the important role of OPTN in ALS pathogenesis, and demonstrate the complex genetics of ALS, as the same mutation leads to different phenotypes and appears in 2 patterns of inheritance. PMID:26740678
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Faivre, L; Guardiola, P; Lewis, C; Dokal, I; Ebell, W; Zatterale, A; Altay, C; Poole, J; Stones, D; Kwee, M L; van Weel-Sipman, M; Havenga, C; Morgan, N; de Winter, J; Digweed, M; Savoia, A; Pronk, J; de Ravel, T; Jansen, S; Joenje, H; Gluckman, E; Mathew, C G
2000-12-15
Fanconi anemia (FA) is a clinically and genetically heterogeneous disorder. Clinical care is complicated by variable age at onset and severity of hematologic symptoms. Recent advances in the molecular biology of FA have allowed us to investigate the relationship between FA genotype and the nature and severity of the clinical phenotype. Two hundred forty-five patients from all 7 known complementation groups (FA-A to FA-G) were studied. Mutations were detected in one of the cloned FANC genes in 169 patients; in the remainder the complementation group was assigned by cell fusion or Western blotting. A range of qualitative and quantitative clinical parameters was compared for each complementation group and for different classes of mutation. Significant phenotypic differences were found. FA-G patients had more severe cytopenia and a higher incidence of leukemia. Somatic abnormalities were less prevalent in FA-C, but more common in the rare groups FA-D, FA-E, and FA-F. In FA-A, patients homozygous for null mutations had an earlier onset of anemia and a higher incidence of leukemia than those with mutations producing an altered protein. In FA-C, there was a later age of onset of aplastic anemia and fewer somatic abnormalities in patients with the 322delG mutation, but there were more somatic abnormalities in patients with IVS4 + 4A --> T. This study indicates that FA patients with mutations in the FANCG gene and patients homozygous for null mutations in FANCA are high-risk groups with a poor hematologic outcome and should be considered as candidates both for frequent monitoring and early therapeutic intervention. (Blood. 2000;96:4064-4070)
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Hypogonadotropic Hypogonadism due to Novel FGFR1 Mutations.
Akkuş, Gamze; Kotan, Leman Damla; Durmaz, Erdem; Mengen, Eda; Turan, İhsan; Ulubay, Ayça; Gürbüz, Fatih; Yüksel, Bilgin; Tetiker, Tamer; Topaloğlu, A Kemal
2017-06-01
The underlying genetic etiology of hypogonadotropic hypogonadism (HH) is heterogeneous. Fibroblast growth factor signaling is pivotal in the ontogeny of gonadotropin-releasing hormone neurons. Loss-of-function mutations in FGFR1 gene cause variable HH phenotypes encompassing pubertal delay to idiopathic HH (IHH) or Kallmann syndrome (KS). As FGFR1 mutations are common, recognizing mutations and associated phenotypes may enhance clinical management. Using a candidate gene approach, we screened 52 IHH/KS patients. We identified three novel (IVS3-1G>C and p.W2X, p.R209C) FGFR1 gene mutations. Despite predictive null protein function, patients from the novel mutation families had normosmic IHH without non-reproductive phenotype. These findings further emphasize the great variability of FGFR1 mutation phenotypes in IHH/KS.
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Orthotopic transplantation of LH receptor knockout and wild-type ovaries.
Chudgar, Daksha; Lei, Zhenmin; Rao, Ch V
2005-10-07
Luteinizing hormone (LH) receptor knockout animals have an ovarian failure due to an arrest in folliculogenesis at the antral stage. As a result, the animals have an infertility phenotype. The present study was undertaken to determine whether this phenotype could be reversed by orthotopic transplantation of wild-type ovaries. The results revealed that transplanting wild-type ovaries into null animals did not result in resumption of estrus cycles. Although the number of different types of follicles increased, none progressed to ovulation. The serum hormone profiles improved, reflecting the ovarian changes. The wild-type animals with null ovaries also failed to cycle and their ovaries and serum hormone levels were more like null animals with their own ovaries. Although the lack of rescue of null ovaries placed into wild-type animals was predicted, the failure of wild-type ovaries placed in null animals was not, which could be due to chronic exposure of transplanted tissue to high circulating LH levels and also possibly due to altered internal milieu in null animals. These findings may have implications for potential future considerations of grafting normal donor ovaries into women who have an ovarian failure resulting from inactivating LH receptor mutations.
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2007-09-01
mechanisms and genetic pathways involved in the pathogenesis of myeloproliferative disease (MPDs) are not well understood. Telomere maintenance and...24). A large body of evidence demonstrates the importance of tyrosine kinase mutations to the development of myeloproliferative disorders
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Branchini, A; Ferrarese, M; Lombardi, S; Mari, R; Bernardi, F; Pinotti, M
2016-10-01
Essentials Potentially null homozygous Factor(F)7 nonsense mutations are associated to variable bleeding symptoms. Readthrough of p.Ser112X (life-threatening) and p.Cys132X (moderate) stop codons was investigated. Readthrough-mediated insertion of wild-type or tolerated residues produce functional proteins. Functional readthrough over homozygous F7 nonsense mutations contributes to the bleeding phenotype. Background Whereas the rare homozygous nonsense mutations causing factor (F)VII deficiency may predict null conditions that are almost completely incompatible with life, they are associated with appreciable differences in hemorrhagic symptoms. The misrecognition of premature stop codons (readthrough) may account for variable levels of functional full-length proteins. Objectives To experimentally evaluate the basal and drug-induced levels of FVII resulting from the homozygous p.Cys132X and p.Ser112X nonsense mutations that are associated with moderate (132X) or life-threatening (112X) symptoms, and that are predicted to undergo readthrough with (132X) or without (112X) production of wild-type FVII. Methods We transiently expressed recombinant FVII (rFVII) nonsense and missense variants in human embryonic kidney 293 cells, and evaluated secreted FVII protein and functional levels by ELISA, activated FX generation, and coagulation assays. Results The levels of functional FVII produced by p.Cys132X and p.Ser112X mutants (rFVII-132X, 1.1% ± 0.2% of wild-type rFVII; rFVII-112X, 0.5% ± 0.1% of wild-type rFVII) were compatible with the occurrence of spontaneous readthrough, which was magnified by the addition of G418 - up to 12% of the wild-type value for the rFVII-132X nonsense variant. The predicted missense variants arising from readthrough abolished (rFVII-132Trp/Arg) or reduced (rFVII-112Trp/Cys/Arg, 22-45% of wild-type levels) secretion and function. These data suggest that the appreciable rescue of p.Cys132X function was driven by reinsertion of the wild-type residue, whereas the minimal p.Ser112X function was explained by missense changes permitting FVII secretion and function. Conclusions The extent of functional readthrough might explain differences in the bleeding phenotype of patients homozygous for F7 nonsense mutations, and prevent null conditions even for the most readthrough-unfavorable mutations. © 2016 International Society on Thrombosis and Haemostasis.
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Favor, Jack; Bradley, Alan; Conte, Nathalie; Janik, Dirk; Pretsch, Walter; Reitmeir, Peter; Rosemann, Michael; Schmahl, Wolfgang; Wienberg, Johannes; Zaus, Irmgard
2009-08-01
In the mouse Pax6 function is critical in a dose-dependent manner for proper eye development. Pax6 contiguous gene deletions were shown to be homozygous lethal at an early embryonic stage. Heterozygotes express belly spotting and extreme microphthalmia. The eye phenotype is more severe than in heterozygous Pax6 intragenic null mutants, raising the possibility that deletions are functionally different from intragenic null mutations or that a region distinct from Pax6 included in the deletions affects eye phenotype. We recovered and identified the exact regions deleted in three new Pax6 deletions. All are homozygous lethal at an early embryonic stage. None express belly spotting. One expresses extreme microphthalmia and two express the milder eye phenotype similar to Pax6 intragenic null mutants. Analysis of Pax6 expression levels and the major isoforms excluded the hypothesis that the deletions expressing extreme microphthalmia are directly due to the action of Pax6 and functionally different from intragenic null mutations. A region distinct from Pax6 containing eight genes was identified for belly spotting. A second region containing one gene (Rcn1) was identified for the extreme microphthalmia phenotype. Rcn1 is a Ca(+2)-binding protein, resident in the endoplasmic reticulum, participates in the secretory pathway and expressed in the eye. Our results suggest that deletion of Rcn1 directly or indirectly contributes to the eye phenotype in Pax6 contiguous gene deletions.
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Comparison null imaging ellipsometry using polarization rotator
NASA Astrophysics Data System (ADS)
Park, Sungmo; Kim, Eunsung; Kim, Jiwon; An, Ilsin
2018-05-01
In this study, two-reflection imaging ellipsometry is carried out to compare the changes in polarization states between two samples. By using a polarization rotator, the parallel and perpendicular components of polarization are easily switched between the two samples being compared. This leads to an intensity image consisting of null and off-null points depending on the difference in optical characteristics between the two samples. This technique does not require any movement of optical elements for nulling and can be used to detect defects or surface contamination for quality control of samples.
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Hfq variant with altered RNA binding functions
Ziolkowska, Katarzyna; Derreumaux, Philippe; Folichon, Marc; Pellegrini, Olivier; Régnier, Philippe; Boni, Irina V.; Hajnsdorf, Eliane
2006-01-01
The interaction between Hfq and RNA is central to multiple regulatory processes. Using site-directed mutagenesis, we have found a missense mutation in Hfq (V43R) which strongly affects2 the RNA binding capacity of the Hfq protein and its ability to stimulate poly(A) tail elongation by poly(A)-polymerase in vitro. In vivo, overexpression of this Hfq variant fails to stimulate rpoS–lacZ expression and does not restore a normal growth rate in hfq null mutant. Cells in which the wild-type gene has been replaced by the hfqV43R allele exhibit a phenotype intermediate between those of the wild-type and of the hfq minus or null strains. This missense mutation derepresses Hfq synthesis. However, not all Hfq functions are affected by this mutation. For example, HfqV43R represses OppA synthesis as strongly as the wild-type protein. The dominant negative effect of the V43R mutation over the wild-type allele suggests that hexamers containing variant and genuine subunits are presumably not functional. Finally, molecular dynamics studies indicate that the V43R substitution mainly changes the position of the K56 and Y55 side chains involved in the Hfq–RNA interaction but has probably no effect on the folding and the oligomerization of the protein. PMID:16449205
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Garcia, Victor; Feldman, Marcus W.; Regoes, Roland R.
2016-01-01
During early human immunodeficiency virus (HIV) infection multiple CD8+ T cell responses are elicited almost simultaneously. These responses exert strong selective pressures on different parts of HIV’s genome, and select for mutations that escape recognition and are thus beneficial to the virus. Some studies reveal that the later these escape mutations emerge, the more slowly they go to fixation. This pattern of escape rate decrease(ERD) can arise by distinct mechanisms. In particular, in large populations with high beneficial mutation rates interference among different escape strains –an effect that can emerge in evolution with asexual reproduction and results in delayed fixation times of beneficial mutations compared to sexual reproduction– could significantly impact the escape rates of mutations. In this paper, we investigated how interference between these concurrent escape mutations affects their escape rates in systems with multiple epitopes, and whether it could be a source of the ERD pattern. To address these issues, we developed a multilocus Wright-Fisher model of HIV dynamics with selection, mutation and recombination, serving as a null-model for interference. We also derived an interference-free null model assuming initial neutral evolution before immune response elicitation. We found that interference between several equally selectively advantageous mutations can generate the observed ERD pattern. We also found that the number of loci, as well as recombination rates substantially affect ERD. These effects can be explained by the underexponential decline of escape rates over time. Lastly, we found that the observed ERD pattern in HIV infected individuals is consistent with both independent, interference-free mutations as well as interference effects. Our results confirm that interference effects should be considered when analyzing HIV escape mutations. The challenge in estimating escape rates and mutation-associated selective coefficients posed by interference effects cannot simply be overcome by improved sampling frequencies or sizes. This problem is a consequence of the fundamental shortcomings of current estimation techniques under interference regimes. Hence, accounting for the stochastic nature of competition between mutations demands novel estimation methodologies based on the analysis of HIV strains, rather than mutation frequencies. PMID:26829720
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USDA-ARS?s Scientific Manuscript database
Polymorphic DNA markers, e.g. mini- or microsatellite (SSR) loci, are often removed from data analyses if an excess of homozygosity, presumably an indication of null alleles, is observed. However, exclusion of such loci can reduce available information if multiple loci carry null alleles. Because nu...
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Nmf9 Encodes a Highly Conserved Protein Important to Neurological Function in Mice and Flies.
Zhang, Shuxiao; Ross, Kevin D; Seidner, Glen A; Gorman, Michael R; Poon, Tiffany H; Wang, Xiaobo; Keithley, Elizabeth M; Lee, Patricia N; Martindale, Mark Q; Joiner, William J; Hamilton, Bruce A
2015-07-01
Many protein-coding genes identified by genome sequencing remain without functional annotation or biological context. Here we define a novel protein-coding gene, Nmf9, based on a forward genetic screen for neurological function. ENU-induced and genome-edited null mutations in mice produce deficits in vestibular function, fear learning and circadian behavior, which correlated with Nmf9 expression in inner ear, amygdala, and suprachiasmatic nuclei. Homologous genes from unicellular organisms and invertebrate animals predict interactions with small GTPases, but the corresponding domains are absent in mammalian Nmf9. Intriguingly, homozygotes for null mutations in the Drosophila homolog, CG45058, show profound locomotor defects and premature death, while heterozygotes show striking effects on sleep and activity phenotypes. These results link a novel gene orthology group to discrete neurological functions, and show conserved requirement across wide phylogenetic distance and domain level structural changes.
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A role for metabolism in Rett syndrome pathogenesis
Justice, Monica J; Buchovecky, Christie M; Kyle, Stephanie M; Djukic, Aleksandra
2013-01-01
Rett syndrome (RTT), an X-linked neurological disorder caused by mutations in MECP2, may have a metabolic component. We reported a genetic suppressor screen in a Mecp2-null mouse model to identify pathways for therapeutic improvement of RTT symptoms. Of note, one suppressor mutation implied that cholesterol homeostasis was perturbed in Mecp2 null mice; indeed, cholesterol synthesis was elevated in the brain and body system. Remarkably, the genetic effect of downregulating the cholesterol pathway could be mimicked chemically by statin drugs, improving motor symptoms, and increasing longevity in the mouse. Our work linked cholesterol metabolism to RTT pathology for the first time. Both neurological and systemic effects of perturbed cholesterol homeostasis overlap with many RTT symptoms. Here we show in patients that peripheral cholesterol, triglycerides, and/or LDLs may be elevated early in RTT disease onset, providing a biomarker for patients that could be aided by therapeutic interventions that modulate lipid metabolism. PMID:25003017
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Regulation of Embryonic and Postnatal Development by the CSF-1 Receptor
Chitu, Violeta; Stanley, E. Richard
2017-01-01
Macrophages are found in all tissues and regulate tissue morphogenesis during development through trophic and scavenger functions. The colony stimulating factor-1 (CSF-1) receptor (CSF-1R) is the major regulator of tissue macrophage development and maintenance. In combination with receptor activator of nuclear factor κB (RANK), the CSF-1R also regulates the differentiation of the bone-resorbing osteoclast and controls bone remodeling during embryonic and early postnatal development. CSF-1R-regulated macrophages play trophic and remodeling roles in development. Outside the mononuclear phagocytic system, the CSF-1R directly regulates neuronal survival and differentiation, the development of intestinal Paneth cells and of preimplantation embryos, as well as trophoblast innate immune function. Consistent with the pleiotropic roles of the receptor during development, CSF-1R deficiency in most mouse strains causes embryonic or perinatal death and the surviving mice exhibit multiple developmental and functional deficits. The CSF-1R is activated by two dimeric glycoprotein ligands, CSF-1, and interleukin-34 (IL-34). Homozygous Csf1-null mutations phenocopy most of the deficits of Csf1r-null mice. In contrast, Il34-null mice have no gross phenotype, except for decreased numbers of Langerhans cells and microglia, indicating that CSF-1 plays the major developmental role. Homozygous inactivating mutations of the Csf1r or its ligands have not been reported in man. However, heterozygous inactivating mutations in the Csf1r lead to a dominantly inherited adult-onset progressive dementia, highlighting the importance of CSF-1R signaling in the brain. PMID:28236968
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Regulation of Embryonic and Postnatal Development by the CSF-1 Receptor.
Chitu, Violeta; Stanley, E Richard
2017-01-01
Macrophages are found in all tissues and regulate tissue morphogenesis during development through trophic and scavenger functions. The colony stimulating factor-1 (CSF-1) receptor (CSF-1R) is the major regulator of tissue macrophage development and maintenance. In combination with receptor activator of nuclear factor κB (RANK), the CSF-1R also regulates the differentiation of the bone-resorbing osteoclast and controls bone remodeling during embryonic and early postnatal development. CSF-1R-regulated macrophages play trophic and remodeling roles in development. Outside the mononuclear phagocytic system, the CSF-1R directly regulates neuronal survival and differentiation, the development of intestinal Paneth cells and of preimplantation embryos, as well as trophoblast innate immune function. Consistent with the pleiotropic roles of the receptor during development, CSF-1R deficiency in most mouse strains causes embryonic or perinatal death and the surviving mice exhibit multiple developmental and functional deficits. The CSF-1R is activated by two dimeric glycoprotein ligands, CSF-1, and interleukin-34 (IL-34). Homozygous Csf1-null mutations phenocopy most of the deficits of Csf1r-null mice. In contrast, Il34-null mice have no gross phenotype, except for decreased numbers of Langerhans cells and microglia, indicating that CSF-1 plays the major developmental role. Homozygous inactivating mutations of the Csf1r or its ligands have not been reported in man. However, heterozygous inactivating mutations in the Csf1r lead to a dominantly inherited adult-onset progressive dementia, highlighting the importance of CSF-1R signaling in the brain. © 2017 Elsevier Inc. All rights reserved.
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BmpR1A is a major type 1 BMP receptor for BMP-Smad signaling during skull development.
Pan, Haichun; Zhang, Honghao; Abraham, Ponnu; Komatsu, Yoshihiro; Lyons, Karen; Kaartinen, Vesa; Mishina, Yuji
2017-09-01
Craniosynostosis is caused by premature fusion of one or more sutures in an infant skull, resulting in abnormal facial features. The molecular and cellular mechanisms by which genetic mutations cause craniosynostosis are incompletely characterized, and many of the causative genes for diverse types of syndromic craniosynostosis have not yet been identified. We previously demonstrated that augmentation of BMP signaling mediated by a constitutively active BMP type IA receptor (ca-BmpR1A) in neural crest cells (ca1A hereafter) causes craniosynostosis and superimposition of heterozygous null mutation of Bmpr1a rescues premature suture fusion (ca1A;1aH hereafter). In this study, we superimposed heterozygous null mutations of the other two BMP type I receptors, Bmpr1b and Acvr1 (ca1A;1bH and ca1A;AcH respectively hereafter) to further dissect involvement of BMP-Smad signaling. Unlike caA1;1aH, ca1A;1bH and ca1A;AcH did not restore the craniosynostosis phenotypes. In our in vivo study, Smad-dependent BMP signaling was decreased to normal levels in mut;1aH mice. However, BMP receptor-regulated Smads (R-Smads; pSmad1/5/9 hereafter) levels were comparable between ca1A, ca1A;1bH and ca1A;AcH mice, and elevated compared to control mice. Bmpr1a, Bmpr1b and Acvr1 null cells were used to examine potential mechanisms underlying the differences in ability of heterozygosity for Bmpr1a vs. Bmpr1b or Acvr1 to rescue the mut phenotype. pSmad1/5/9 level was undetectable in Bmpr1a homozygous null cells while pSmad1/5/9 levels did not decrease in Bmpr1b or Acvr1 homozygous null cells. Taken together, our study indicates that different levels of expression and subsequent activation of Smad signaling differentially contribute each BMP type I receptor to BMP-Smad signaling and craniofacial development. These results also suggest differential involvement of each type 1 receptor in pathogenesis of syndromic craniosynostoses. Copyright © 2017 Elsevier Inc. All rights reserved.
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Molecular basis of the Duffy blood group system
Höher, Gabriela; Fiegenbaum, Marilu; Almeida, Silvana
2018-01-01
ACKR1, located on chromosome 1q23.2, is the gene that encodes a glycoprotein expressing the Duffy blood group antigens. This gene is transcribed in two mRNA variants yielding two isoforms, encoding proteins with 338 and 336 amino acids. This review provides a general overview of the Duffy blood group to characterise and elucidate the genetic basis of this system. The Fya and Fyb antigens are encoded by co-dominant FY*A (FY*01) and FY*B (FY*02) alleles, which differ by c.125G>A (rs12075), defining the Fy(a+b−), Fy(a−b+) and Fy(a+b+) phenotypes. The Fy(a−b−) phenotype that occurs in Africans provides an explanation for the apparent absence of Plasmodium vivax in this region: this phenotype arises from homozygosity for the FY*B allele carrying a point mutation c.1-67T>C (rs2814778), which prevents Fyb antigen expression only in red blood cells. The same mutation has also been found on the FY*A allele, but it is very rare. The Fy(a−b−) phenotype in Europeans and Asians arises from mutations in the coding region of the FY*A or FY*B allele, preventing Duffy antigen expression on any cell in the body and thus are true Duffy null phenotypes. According to the International Society for Blood Transfusion, ten alleles are associated with the null expression of the Fy antigens. Furthermore, different allelic forms of FY*B modify Fyb antigen expression, which may result in very weak or equivocal serology results. The mostly common found variants, c.265C>T (rs34599082) and c.298G>A (rs13962) -previously defined in combination only with the FY*B allele - have already been observed in the FY*A allele. Thus, six alleles have been recognised and associated with weak expression of the Fy antigens. Considering the importance of the Duffy blood group system in clinical medicine, additional studies via molecular biology approaches must be performed to resolve and clarify the discrepant results that are present in the erythrocyte phenotyping. PMID:28151395
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Molecular basis of the Duffy blood group system.
Höher, Gabriela; Fiegenbaum, Marilu; Almeida, Silvana
2018-01-01
ACKR1, located on chromosome 1q23.2, is the gene that encodes a glycoprotein expressing the Duffy blood group antigens. This gene is transcribed in two mRNA variants yielding two isoforms, encoding proteins with 338 and 336 amino acids. This review provides a general overview of the Duffy blood group to characterise and elucidate the genetic basis of this system. The Fy a and Fy b antigens are encoded by co-dominant FY*A (FY*01) and FY*B (FY*02) alleles, which differ by c.125G>A (rs12075), defining the Fy(a+b-), Fy(a-b+) and Fy(a+b+) phenotypes. The Fy(a-b-) phenotype that occurs in Africans provides an explanation for the apparent absence of Plasmodium vivax in this region: this phenotype arises from homozygosity for the FY*B allele carrying a point mutation c.1-67T>C (rs2814778), which prevents Fy b antigen expression only in red blood cells. The same mutation has also been found on the FY*A allele, but it is very rare. The Fy(a-b-) phenotype in Europeans and Asians arises from mutations in the coding region of the FY*A or FY*B allele, preventing Duffy antigen expression on any cell in the body and thus are true Duffy null phenotypes. According to the International Society for Blood Transfusion, ten alleles are associated with the null expression of the Fy antigens. Furthermore, different allelic forms of FY*B modify Fy b antigen expression, which may result in very weak or equivocal serology results. The mostly common found variants, c.265C>T (rs34599082) and c.298G>A (rs13962) -previously defined in combination only with the FY*B allele - have already been observed in the FY*A allele. Thus, six alleles have been recognised and associated with weak expression of the Fy antigens. Considering the importance of the Duffy blood group system in clinical medicine, additional studies via molecular biology approaches must be performed to resolve and clarify the discrepant results that are present in the erythrocyte phenotyping.
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MMP20 Promotes a Smooth Enamel Surface, a Strong DEJ, and a Decussating Enamel Rod Pattern
Bartlett, John D.; Skobe, Ziedonis; Nanci, Antonio; Smith, Charles E.
2012-01-01
Mutations of the Matrix metalloproteinase-20 (MMP20, enamelysin) gene cause autosomal recessive amelogenesis imperfecta and Mmp20 ablated mice also have malformed dental enamel. Here we show that Mmp20 null mouse secretory stage ameloblasts maintained a columnar shape and were present as a single layer of cells. However, the null maturation stage ameloblasts covered extraneous nodules of ectopic calcified material formed at the enamel surface. Remarkably, nodule formation occurs in null mouse enamel when MMP20 is normally no longer expressed. The malformed enamel in Mmp20 null teeth was loosely attached to the dentin and the entire enamel layer tended to separate from the dentin indicative of a faulty DEJ. The enamel rod pattern was also altered in Mmp20 null mice. Each enamel rod is formed by a single ameloblast and is a mineralized record of the migration path of the ameloblast that formed it. The Mmp20 null mouse enamel rods were grossly malformed or were absent indicating that the ameloblasts do not migrate properly when backing away from the DEJ. Thus, MMP20 is required for ameloblast cell movement necessary to form the decussating enamel rod patterns, for the prevention of ectopic mineral formation, and to maintain a functional DEJ. PMID:22243247
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Huynh, Julie M.; Dang, Hope; Munoz-Tucker, Isabel A.; O’Ketch, Marvin; Liu, Ian T.; Perno, Savannah; Bhuyan, Natasha; Crain, Allison; Borbon, Ivan; Fares, Hanna
2016-01-01
Mutations in MCOLN1, which encodes the cation channel protein TRPML1, result in the neurodegenerative lysosomal storage disorder Mucolipidosis type IV. Mucolipidosis type IV patients show lysosomal dysfunction in many tissues and neuronal cell death. The ortholog of TRPML1 in Caenorhabditis elegans is CUP-5; loss of CUP-5 results in lysosomal dysfunction in many tissues and death of developing intestinal cells that results in embryonic lethality. We previously showed that a null mutation in the ATP-Binding Cassette transporter MRP-4 rescues the lysosomal defect and embryonic lethality of cup-5(null) worms. Here we show that reducing levels of the Endosomal Sorting Complex Required for Transport (ESCRT)-associated proteins DID-2, USP-50, and ALX-1/EGO-2, which mediate the final de-ubiquitination step of integral membrane proteins being sequestered into late endosomes, also almost fully suppresses cup-5(null) mutant lysosomal defects and embryonic lethality. Indeed, we show that MRP-4 protein is hypo-ubiquitinated in the absence of CUP-5 and that reducing levels of ESCRT-associated proteins suppresses this hypo-ubiquitination. Thus, increased ESCRT-associated de-ubiquitinating activity mediates the lysosomal defects and corresponding cell death phenotypes in the absence of CUP-5. PMID:26596346
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Weilbacher, A; Gutekunst, M; Oren, M; Aulitzky, W E; van der Kuip, H
2014-01-01
Significant advances have been made in the development of small molecules blocking the p53/MDM2 interaction. The Mdm2 inhibitor Nutlin-3 is restricted to tumors carrying wtp53. In contrast, RITA, a compound that binds p53, has recently been shown also to restore transcriptional functions of mtp53. As more than 50% of solid tumors carry p53 mutations, RITA promises to be a more effective therapeutic strategy than Nutlin-3. We investigated effects of RITA on apoptosis, cell cycle and induction of 45 p53 target genes in a panel of 14 cell lines from different tumor entities with different p53 status as well as primary lymphocytes and fibroblasts. Nine cell strains expressed wtp53, four harbored mtp53, and three were characterized by the loss of p53 protein. A significant induction of cell death upon RITA was observed in 7 of 16 cell lines. The nonmalignant cells in our panel were substantially less sensitive. We found that in contrast to Nultin-3, RITA is capable to induce cell death not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells. Importantly, whereas p53 has a central role for RITA-mediated effects in wtp53 cells, neither p53 nor p63 or p73 were essential for the RITA response in mtp53 or p53-null cells in our panel demonstrating that besides the known p53-dependent action of RITA in wtp53 cells, RITA can induce cell death also independently of p53 in cells harboring defective p53. We identified an important role of both p38 and JNK/SAPK for sensitivity to RITA in these cells leading to a typical caspase- and BAX/BAK-dependent mitochondrial apoptosis. In conclusion, our data demonstrate that RITA can induce apoptosis through p38 and JNK/SAPK not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells, making RITA an interesting tumor-selective drug. PMID:25010984
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Weilbacher, A; Gutekunst, M; Oren, M; Aulitzky, W E; van der Kuip, H
2014-07-10
Significant advances have been made in the development of small molecules blocking the p53/MDM2 interaction. The Mdm2 inhibitor Nutlin-3 is restricted to tumors carrying wtp53. In contrast, RITA, a compound that binds p53, has recently been shown also to restore transcriptional functions of mtp53. As more than 50% of solid tumors carry p53 mutations, RITA promises to be a more effective therapeutic strategy than Nutlin-3. We investigated effects of RITA on apoptosis, cell cycle and induction of 45 p53 target genes in a panel of 14 cell lines from different tumor entities with different p53 status as well as primary lymphocytes and fibroblasts. Nine cell strains expressed wtp53, four harbored mtp53, and three were characterized by the loss of p53 protein. A significant induction of cell death upon RITA was observed in 7 of 16 cell lines. The nonmalignant cells in our panel were substantially less sensitive. We found that in contrast to Nultin-3, RITA is capable to induce cell death not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells. Importantly, whereas p53 has a central role for RITA-mediated effects in wtp53 cells, neither p53 nor p63 or p73 were essential for the RITA response in mtp53 or p53-null cells in our panel demonstrating that besides the known p53-dependent action of RITA in wtp53 cells, RITA can induce cell death also independently of p53 in cells harboring defective p53. We identified an important role of both p38 and JNK/SAPK for sensitivity to RITA in these cells leading to a typical caspase- and BAX/BAK-dependent mitochondrial apoptosis. In conclusion, our data demonstrate that RITA can induce apoptosis through p38 and JNK/SAPK not only in tumor cells harboring wtp53 and mtp53 but also in p53-null cells, making RITA an interesting tumor-selective drug.
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Bremer, Jeroen; Bornert, Olivier; Nyström, Alexander; Gostynski, Antoni; Jonkman, Marcel F; Aartsma-Rus, Annemieke; van den Akker, Peter C; Pasmooij, Anna Mg
2016-10-18
The "generalized severe" form of recessive dystrophic epidermolysis bullosa (RDEB-gen sev) is caused by bi-allelic null mutations in COL7A1, encoding type VII collagen. The absence of type VII collagen leads to blistering of the skin and mucous membranes upon the slightest trauma. Because most patients carry exonic point mutations or small insertions/deletions, most exons of COL7A1 are in-frame, and low levels of type VII collagen already drastically improve the disease phenotype, this gene seems a perfect candidate for antisense oligonucleotide (AON)-mediated exon skipping. In this study, we examined the feasibility of AON-mediated exon skipping in vitro in primary cultured keratinocytes and fibroblasts, and systemically in vivo using a human skin-graft mouse model. We show that treatment with AONs designed against exon 105 leads to in-frame exon 105 skipping at the RNA level and restores type VII collagen protein production in vitro. Moreover, we demonstrate that systemic delivery in vivo induces de novo expression of type VII collagen in skin grafts generated from patient cells. Our data demonstrate strong proof-of-concept for AON-mediated exon skipping as a systemic therapeutic strategy for RDEB.
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Effects of hypo-O-GlcNAcylation on Drosophila development.
Mariappa, Daniel; Ferenbach, Andrew T; van Aalten, Daan M F
2018-05-11
Post-translational modification of serine/threonine residues in nucleocytoplasmic proteins with GlcNAc ( O -GlcNAcylation) is an essential regulatory mechanism in many cellular processes. In Drosophila , null mutants of the Polycomb gene O -GlcNAc transferase ( OGT ; also known as super sex combs ( sxc )) display homeotic phenotypes. To dissect the requirement for O -GlcNAc signaling in Drosophila development, we used CRISPR/Cas9 gene editing to generate rationally designed sxc catalytically hypomorphic or null point mutants. Of the fertile males derived from embryos injected with the CRISPR/Cas9 reagents, 25% produced progeny carrying precise point mutations with no detectable off-target effects. One of these mutants, the catalytically inactive sxc K872M , was recessive lethal, whereas a second mutant, the hypomorphic sxc H537A , was homozygous viable. We observed that reduced total protein O -GlcNAcylation in the sxc H537A mutant is associated with a wing vein phenotype and temperature-dependent lethality. Genetic interaction between sxc H537A and a null allele of Drosophila host cell factor ( dHcf ), encoding an extensively O -GlcNAcylated transcriptional coactivator, resulted in abnormal scutellar bristle numbers. A similar phenotype was also observed in sxc H537A flies lacking a copy of skuld ( skd ), a Mediator complex gene known to affect scutellar bristle formation. Interestingly, this phenotype was independent of OGT Polycomb function or dHcf downstream targets. In conclusion, the generation of the endogenous OGT hypomorphic mutant sxc H537A enabled us to identify pleiotropic effects of globally reduced protein O -GlcNAc during Drosophila development. The mutants generated and phenotypes observed in this study provide a platform for discovery of OGT substrates that are critical for Drosophila development. © 2018 Mariappa et al.
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Petkau, Terri L; Blanco, Jake; Leavitt, Blair R
2017-10-01
Progranulin deficiency due to heterozygous null mutations in the GRN gene is a common cause of familial frontotemporal lobar degeneration (FTLD), while homozygous loss-of-function GRN mutations cause neuronal ceroid lipofuscinosis (NCL). Aged progranulin-knockout mice display highly exaggerated lipofuscinosis, microgliosis, and astrogliosis, as well as mild cell loss in specific brain regions. Progranulin is a secreted glycoprotein expressed in both neurons and microglia, but not astrocytes, in the brain. We generated conditional progranulin-knockout mice that lack progranulin in nestin-expressing cells (Nes-cKO mice), which include most neurons as well as astrocytes. We confirmed near complete knockout of progranulin in neurons in Nes-cKO mice, while microglial progranulin levels remained similar to that of wild-type animals. Overall brain progranulin levels were reduced by about 50% in Nes-cKO, and no Grn was detected in primary Nes-cKO neurons. Nes-cKO mice aged to 12months did not display any increase in lipofuscin deposition, microgliosis, or astrogliosis in the four brain regions examined, though increases were observed for most of these measures in Grn-null animals. We conclude that neuron-specific loss of progranulin is not sufficient to cause similar neuropathological changes to those seen in constitutive Grn-null animals. Our results suggest that increased lipofuscinosis and gliosis in Grn-null animals are not caused by intrinsic progranulin deficiency in neurons, and that microglia-derived progranulin may be sufficient to maintain neuronal health and homeostasis in the brain. Copyright © 2017 Elsevier Inc. All rights reserved.
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Inokuchi, Shota; Yamashita, Yasuhiro; Nishimura, Kazuma; Nakanishi, Hiroaki; Saito, Kazuyuki
2017-11-01
Phenomena known as null alleles and peak imbalance can occur because of mutations in the primer binding sites used for DNA typing. In these cases, an accurate statistical evaluation of DNA typing is difficult. The estimated likelihood ratio is incorrectly calculated because of the null allele and allele dropout caused by mutation-induced peak imbalance. Although a number of studies have attempted to uncover examples of these phenomena, few reports are available on the human identification kit manufactured by Qiagen. In this study, 196 Japanese individuals who were heterozygous at D2S1360 were genotyped using an Investigator HDplex Kit with optimal amounts of DNA. A peak imbalance was frequently observed at the D2S1360 locus. We performed a sequencing analysis of the area surrounding the D2S1360 repeat motif to identify the cause for peak imbalance. A point mutation (G>A transition) 136 nucleotides upstream from the D2S1360 repeat motif was discovered in a number of samples. The allele frequency of the mutation was 0.0566 in the Japanese population. Therefore, human identification or kinship testing using the Investigator HDplex Kit requires caution because of the higher frequency of single nucleotide polymorphisms at the primer binding site of D2S1360 locus in the Japanese population.
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Galimberti, Daniela; Fumagalli, Giorgio G; Fenoglio, Chiara; Cioffi, Sara M G; Arighi, Andrea; Serpente, Maria; Borroni, Barbara; Padovani, Alessandro; Tagliavini, Fabrizio; Masellis, Mario; Tartaglia, Maria Carmela; van Swieten, John; Meeter, Lieke; Graff, Caroline; de Mendonça, Alexandre; Bocchetta, Martina; Rohrer, Jonathan D; Scarpini, Elio
2018-02-01
We investigated whether progranulin plasma levels are predictors of the presence of progranulin gene (GRN) null mutations or of the development of symptoms in asymptomatic at risk members participating in the Genetic Frontotemporal Dementia Initiative, including 19 patients, 64 asymptomatic carriers, and 77 noncarriers. In addition, we evaluated a possible role of TMEM106B rs1990622 as a genetic modifier and correlated progranulin plasma levels and gray-matter atrophy. Plasma progranulin mean ± SD plasma levels in patients and asymptomatic carriers were significantly decreased compared with noncarriers (30.5 ± 13.0 and 27.7 ± 7.5 versus 99.6 ± 24.8 ng/mL, p < 0.00001). Considering the threshold of >61.55 ng/mL, the test had a sensitivity of 98.8% and a specificity of 97.5% in predicting the presence of a mutation, independent of symptoms. No correlations were found between progranulin plasma levels and age, years from average age at onset in each family, or TMEM106B rs1990622 genotype (p > 0.05). Plasma progranulin levels did not correlate with brain atrophy. Plasma progranulin levels predict the presence of GRN null mutations independent of proximity to symptoms and brain atrophy. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.
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Nielsen, Jytte Bieber; Nielsen, Karin E; Güttler, Flemming
2010-02-01
Phenylketonuria (PKU) is an inherited metabolic disease characterized by phenylalanine (Phe) accumulation due to defects in the enzyme phenylalanine hydroxylase (PAH). Phe accumulation can lead to cognitive impairment. Some individuals with PKU respond to tetrahydrobiopterin (BH4) treatment, the natural cofactor of PAH, by a reduction in blood Phe concentrations.We tested 12 patients with PKU, 8-29 years of age, all carrying the common Y414C mutation in the PAH gene. Three were homozygous and nine were compound heterozygous, with the second mutation being a putative null mutation. During the study period, genuine protein was increased to approximately 1 g/kg. The patients were treated with 20, 10, and 5 mg BH4/kg/day for 1 week on each dose, starting with 20 mg/kg. A positive response was defined as a decline in blood Phe>30%. Blood Phe was measured four times a week. Nonresponding children were excluded from the study. Eleven of 12 patients had a positive response with 20 mg/kg, 5/10 responded on 10 mg/kg, and 1/9 on 5 mg/kg. Two were late responders, with a response on 20 mg/kg after >48 h. We could confirm the previously reported inconsistent responsiveness of Y414C in the nine heterozygous patients, whereas the three homozygous patients had early median Phe declines of 73%, 51%, and 27%, respectively, on the three different doses. The varying responses despite uniform trial conditions and genotypes may be due to individual differences in BH4 absorption or metabolism. No side effects were observed.
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Petkau, Terri L; Kosior, Natalia; de Asis, Kathleen; Connolly, Colúm; Leavitt, Blair R
2017-11-17
Progranulin deficiency due to heterozygous null mutations in the GRN gene are a common cause of familial frontotemporal lobar degeneration (FTLD), while homozygous loss-of-function GRN mutations are thought to be a rare cause of neuronal ceroid lipofuscinosis (NCL). Aged progranulin-knockout (Grn-null) mice display highly exaggerated lipofuscinosis, microgliosis, and astrogliosis, as well as mild cell loss in specific brain regions. In the brain, progranulin is predominantly expressed in neurons and microglia, and previously, we demonstrated that neuronal-specific depletion of progranulin does not recapitulate the neuropathological phenotype of Grn-null mice. In this study, we evaluated whether selective depletion of progranulin expression in myeloid-lineage cells, including microglia, causes NCL-like neuropathology or neuroinflammation in mice. We generated mice with progranulin depleted in myeloid-lineage cells by crossing mice homozygous for a floxed progranulin allele to mice expressing Cre recombinase under control of the LyzM promotor (Lyz-cKO). Progranulin expression was reduced by approximately 50-70% in isolated microglia compared to WT levels. Lyz-cKO mice aged to 12 months did not display any increase in lipofuscin deposition, microgliosis, or astrogliosis in the four brain regions examined, though increases were observed for many of these measures in Grn-null animals. To evaluate the functional effect of reduced progranulin expression in isolated microglia, primary cultures were stimulated with controlled standard endotoxin and cytokine release was measured. While Grn-null microglia display a hyper-inflammatory phenotype, Lyz-cKO and WT microglia secreted similar levels of inflammatory cytokines. We conclude that progranulin expression from either microglia or neurons is sufficient to prevent the development of NCL-like neuropathology in mice. Furthermore, microglia that are deficient for progranulin expression but isolated from a progranulin-rich environment have a normal inflammatory profile. Our results suggest that progranulin acts, at least partly, in a non-cell autonomous manner in the brain.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, X.; Fleischer, D.T.; Whitehead, W.T.
1995-05-15
Hereditary C5 deficiency has been reported in several families of different ethnic backgrounds and from different geographic regions, but the molecular genetic defect causing C5 deficiency has not been delineated in any of them. To examine the molecular basis of C5 deficiency in the African-American population, the exons and intron/exon boundaries of the C5 structural genes from three C5-deficient (C5D) African-American families were sequenced, revealing two nonsense mutations. The nonsense mutations are located in exon 1 (C{sup 84}AG to TAG) in two of the C5D families (Rhode Island and North Carolina) and in exon 36 (C{sup 4521}GA to TGA) inmore » the third C5D family (New York). The exon 1 and 36 mutations are contained in codons that encode the first amino acid of the C5 {beta}-chain (Gln{sup 1} to Stop) and residue 1458 in the {alpha}-chain (Arg{sup 1458} to Stop), respectively. Allele-specific PCR and sequence analyses demonstrated that the exon 1 mutation is present in only one of the C5 null genes in both the Rhode Island and North Carolina families, and the exon 36 mutation is contained in only one C5 null gene in the New York family. Neither of the nonsense mutations was found in the European or Caucasian-American C5D individuals examined. Collectively, these data indicate that: (1) C5 deficiency is caused by several different molecular genetic defects, (2) C5 deficiency in the African-American population can be explained in part by two distinct nonsense mutations in exons 1 and 36, and (3) compound heterozygosity exists in all of the reported African-American C5D families. 44 refs., 5 figs., 1 tab.« less
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Light cone structure near null infinity of the Kerr metric
DOE Office of Scientific and Technical Information (OSTI.GOV)
Bai Shan; Shang Yu; Graduate School of Chinese Academy of Sciences, Beijing, 100080
2007-02-15
Motivated by our attempt to understand the question of angular momentum of a relativistic rotating source carried away by gravitational waves, in the asymptotic regime near future null infinity of the Kerr metric, a family of null hypersurfaces intersecting null infinity in shearfree (good) cuts are constructed by means of asymptotic expansion of the eikonal equation. The geometry of the null hypersurfaces as well as the asymptotic structure of the Kerr metric near null infinity are studied. To the lowest order in angular momentum, the Bondi-Sachs form of the Kerr metric is worked out. The Newman-Unti formalism is then furthermore » developed, with which the Newman-Penrose constants of the Kerr metric are computed and shown to be zero. Possible physical implications of the vanishing of the Newman-Penrose constants of the Kerr metric are also briefly discussed.« less
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Schroeder, B; Hesse, L; Brück, W; Gal, A
1997-06-01
To determine the clinical, histopathological, and immunohistochemical ocular changes associated with a null mutation in the Norrie disease protein (NDP) gene. Tissue from a six-month-old boy with bilateral retrolental membranes and retinal detachment was obtained during vitreoretinal surgery. Histological sections were stained immunohistochemically with specific antibodies. No eye diseases with severe visual impairment or blindness were reported in the parents and their families. The NDP gene was analyzed by standard molecular genetic methods. A severe reduction in the number of retinal ganglion cells and a largely disarranged and hypoplastic inner nuclear layer were visible in the tissue specimen. Areas of the tissue with advanced pathology displayed massive fibrovascular proliferation in the vitreous cavity. Shrinkage and traction resulted in folding and detachment of the outer retina. Immunohistochemical reactivity for MIB(1) antigen demonstrated many proliferating cells in the vitreous, but no proliferative activity in the neuroretina. Retinal neurons showed a high grade of differentiation and expressed uniformly neuron-specific enolase and synaptophysin. A 1-base pair insertion (544/545insA) in the NDP gene was found in the affected boy. This mutation predicts a 'functional null-allele' due to a shift in the reading frame and, thus, a premature termination of mRNA translation after 55 instead of 133 amino acids. Loss of function of the NDP gene causes marked hypoplasia of the inner retinal cell layers and fibrovascular proliferation in the vitreous cavity, leading to retinal folding and detachment. The NDP therefore seems to play a critical role in terminal differentiation of the inner retinal cell layers and establishment and maintaining of anti-proliferative cellular interactions in the vitreous.
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Absence of Wip1 partially rescues Atm deficiency phenotypes in mice
Darlington, Yolanda; Nguyen, Thuy-Ai; Moon, Sung-Hwan; Herron, Alan; Rao, Pulivarthi; Zhu, Chengming; Lu, Xiongbin; Donehower, Lawrence A.
2011-01-01
Wildtype p53-Induced Phosphatase 1 (WIP1) is a serine/threonine phosphatase that dephosphorylates proteins in the ataxia telangiectasia mutated (ATM)-initiated DNA damage response pathway. WIP1 may play a homeostatic role in ATM signaling by returning the cell to a normal pre-stress state following completion of DNA repair. To better understand the effects of WIP1 on ATM signaling, we crossed Atm-deficient mice to Wip1-deficient mice and characterized phenotypes of the double knockout progeny. We hypothesized that the absence of Wip1 might rescue Atm deficiency phenotypes. Atm null mice, like ATM-deficient humans with the inherited syndrome ataxia telangiectasia, exhibit radiation sensitivity, fertility defects, and are T-cell lymphoma prone. Most double knockout mice were largely protected from lymphoma development and had a greatly extended lifespan compared to Atm null mice. Double knockout mice had increased p53 and H2AX phosphorylation and p21 expression compared to their Atm null counterparts, indicating enhanced p53 and DNA damage responses. Additionally, double knockout splenocytes displayed reduced chromosomal instability compared to Atm null mice. Finally, doubly null mice were partially rescued from infertility defects observed in Atm null mice. These results indicate that inhibition of WIP1 may represent a useful strategy for cancer treatment in general and A-T patients in particular. PMID:21765465
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Venkei, Zsolt; Szabad, János
2005-06-01
The dominant-negative female-sterile Kavar(D) mutations and their revertant kavar(r) alleles identify the alphaTubulin67C gene of Drosophila melanogaster, which codes for the maternally provided alpha-tubulin(4) isoform. The mutations result in the formation of monopolar, collapsed spindles (each with two nearby centrosomes, a tassel of microtubules and overcondensed chromosomes), thus revealing a novel function for alpha-tubulin(4) in spindle maintenance and elongation. Molecular features of the two Kavar(D) alleles and a kavar(null) allele are described and models for their actions are discussed.
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Şahin, Aslı; Held, Aaron; Bredvik, Kirsten; Major, Paxton; Achilli, Toni-Marie; Kerson, Abigail G; Wharton, Kristi; Stilwell, Geoff; Reenan, Robert
2017-02-01
Amyotrophic Lateral Sclerosis (ALS) is the most common adult-onset motor neuron disease and familial forms can be caused by numerous dominant mutations of the copper-zinc superoxide dismutase 1 (SOD1) gene. Substantial efforts have been invested in studying SOD1-ALS transgenic animal models; yet, the molecular mechanisms by which ALS-mutant SOD1 protein acquires toxicity are not well understood. ALS-like phenotypes in animal models are highly dependent on transgene dosage. Thus, issues of whether the ALS-like phenotypes of these models stem from overexpression of mutant alleles or from aspects of the SOD1 mutation itself are not easily deconvolved. To address concerns about levels of mutant SOD1 in disease pathogenesis, we have genetically engineered four human ALS-causing SOD1 point mutations (G37R, H48R, H71Y, and G85R) into the endogenous locus of Drosophila SOD1 (dsod) via ends-out homologous recombination and analyzed the resulting molecular, biochemical, and behavioral phenotypes. Contrary to previous transgenic models, we have recapitulated ALS-like phenotypes without overexpression of the mutant protein. Drosophila carrying homozygous mutations rendering SOD1 protein enzymatically inactive (G85R, H48R, and H71Y) exhibited neurodegeneration, locomotor deficits, and shortened life span. The mutation retaining enzymatic activity (G37R) was phenotypically indistinguishable from controls. While the observed mutant dsod phenotypes were recessive, a gain-of-function component was uncovered through dosage studies and comparisons with age-matched dsod null animals, which failed to show severe locomotor defects or nerve degeneration. We conclude that the Drosophila knock-in model captures important aspects of human SOD1-based ALS and provides a powerful and useful tool for further genetic studies. Copyright © 2017 by the Genetics Society of America.
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Yong, Rita Y Y; Gan, Linda S H; Chang, Yuet Meng; Yap, Eric P H
2007-11-01
Amelogenin paralogs on Chromosome X (AMELX) and Y (AMELY) are commonly used sexing markers. Interstitial deletion of Yp involving the AMELY locus has previously been reported. The combined frequency of the AMELY null allele in Singapore and Malaysia populations is 2.7%, 0.6% in Indian and Malay ethnic groups respectively. It is absent among 541 Chinese screened. The null allele in this study belongs to 3 Y haplogroups; J2e1 (85.7%), F* (9.5%) and D* (4.8%). Low and high-resolution STS mapping, followed by sequence analysis of breakpoint junction confirmed a large deletion of 3 to 3.7-Mb located at the Yp11.2 region. Both breakpoints were located in TSPY repeat arrays, suggesting a non-allelic homologous recombination (NAHR) mechanism of deletion. All regional null samples shared identical breakpoint sequences according to their haplogroup affiliation, providing molecular evidence of a common ancestry origin for each haplogroup, and at least 3 independent deletion events recurred in history. The estimated ages based on Y-SNP and STR analysis were approximately 13.5 +/- 3.1 kyears and approximately 0.9 +/- 0.9 kyears for the J2e1 and F* mutations, respectively. A novel polymorphism G > A at Y-GATA-H4 locus in complete linkage disequilibrium with J2e1 null mutations is a more recent event. This work re-emphasizes the need to include other sexing markers for gender determination in certain regional populations. The frequency difference among global populations suggests it constitutes another structural variation locus of human chromosome Y. The breakpoint sequences provide further information to a better understanding of the NAHR mechanism and DNA rearrangements due to higher order genomic architecture.
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Gerlai, R; Adams, B; Fitch, T; Chaney, S; Baez, M
2002-08-01
mGluR8 is a G-protein coupled metabotropic glutamate receptor expressed in the mammalian brain. Members of the mGluR family have been shown to be modulators of neural plasticity and learning and memory. Here we analyze the consequences of a null mutation at the mGluR8 gene locus generated using homologous recombination in embryonic stem cells by comparing the learning performance of the mutants with that of wild type controls in the Morris water maze (MWM) and the context and cue dependent fear conditioning (CFC). Our results revealed robust performance deficits associated with the genetic background, the ICR outbred strain, in both mGluR8 null mutant and the wild type control mice. Mice of this strain origin suffered from impaired vision as compared to CD1 or C57BL/6 mice, a significant impediment in MWM, a visuo-spatial learning task. The CFC task, being less dependent on visual cues, allowed us to reveal subtle performance deficits in the mGluR8 mutants: novelty induced hyperactivity and temporally delayed and blunted responding to shocks and temporally delayed responding to contextual stimuli were detected. The role of mGluR8 as a presynaptic autoreceptor and its contribution to cognitive processes are hypothesized and the utility of gene targeting as compared to pharmacological methods is discussed.
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Dolores, Jazel; Satchell, Karla J. F.
2013-01-01
ABSTRACT Vibrio cholerae genome sequences were analyzed for variation in the rtxA gene that encodes the multifunctional autoprocessing RTX (MARTX) toxin. To accommodate genomic analysis, a discrepancy in the annotated rtxA start site was resolved experimentally. The correct start site is an ATG downstream from rtxC resulting in a gene of 13,638 bp and deduced protein of 4,545 amino acids. Among the El Tor O1 and closely related O139 and O37 genomes, rtxA was highly conserved, with nine alleles differing by only 1 to 6 nucleotides in 100 years. In contrast, 12 alleles from environment-associated isolates are highly variable, at 1 to 3% by nucleotide and 3 to 7% by amino acid. The difference in variation rates did not represent a bias for conservation of the El Tor rtxA compared to that of other strains but rather reflected the lack of gene variation in overall genomes. Three alleles were identified that would affect the function of the MARTX toxin. Two environmental isolates carry novel arrangements of effector domains. These include a variant from RC385 that would suggest an adenylate cyclase toxin and from HE-09 that may have actin ADP-ribosylating activity. Within the recently emerged altered El Tor strains that have a classical ctxB gene, a mutation arose in rtxA that introduces a premature stop codon that disabled toxin function. This null mutant is the genetic background for subsequent emergence of the ctxB7 allele resulting in the strain that spread into Haiti in 2010. Thus, similar to classical strains, the altered El Tor pandemic strains eliminated rtxA after acquiring a classical ctxB. PMID:23592265
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Carter, Michelle Qiu; Louie, Jacqueline W; Huynh, Steven; Parker, Craig T
2014-12-01
We previously reported significantly different acid resistance between curli variants derived from the same Escherichia coli O157:H7 strain, although the curli fimbriae were not associated with this phenotypic divergence. Here we investigated the underlying molecular mechanism by examining the genes encoding the common transcriptional regulators of curli biogenesis and acid resistance. rpoS null mutations were detected in all curli-expressing variants of the 2006 spinach-associated outbreak strains, whereas a wild-type rpoS was present in all curli-deficient variants. Consequently curli-expressing variants were much more sensitive to various stress challenges than curli-deficient variants. This loss of general stress fitness appeared solely to be the result of rpoS mutation since the stress resistances could be restored in curli-expressing variants by a functional rpoS. Comparative transcriptomic analyses between the curli variants revealed a large number of differentially expressed genes, characterized by the enhanced expression of metabolic genes in curli-expressing variants, but a marked decrease in transcription of genes related to stress resistances. Unlike the curli-expressing variants of the 1993 US hamburger-associated outbreak strains (Applied Environmental Microbiology 78: 7706-7719), all curli-expressing variants of the 2006 spinach-associated outbreak strains carry a functional rcsB gene, suggesting an alternative mechanism governing intra-strain phenotypic divergence in E. coli O157:H7. Published by Elsevier Ltd.
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Nanda, A; Salvetti, A P; Martinez-Fernandez de la Camara, C; MacLaren, R E
2018-06-01
Inherited retinal diseases are thought to be the leading cause of sight loss in the working age population. Mutations found in the RPGR and CHM genes cause retinitis pigmentosa (RP) and choroideremia, respectively. In the first instance, an X-linked family history of visual field loss commonly raises the suspicion of one of these two genes. In choroideremia, the classic description of a white fundal reflex secondary to the widespread chorioretinal degeneration was made over a hundred years ago in Caucasians. But, it is not so obvious in heavily pigmented fundi. Hence, the clinical diagnosis of CHM in non-Caucasian patients may be challenging in the first stages of the disease. Here we report a case of a Southeast Asian gentleman who has a family history of X-linked retinal degeneration and was found to have a confirmed in-frame deletion of 12 DNA nucleotides in exon 15 of the RPGR gene. Later in life, however, his fundal appearance showed unusual areas of circular pigment hypertrophy and clumping. He was therefore tested for carrying a disease-causing mutation in the CHM gene and a null mutation was found. Since gene therapy trials are ongoing for both of these conditions, it has now become critically important to establish the correct genetic diagnosis in order to recruit suitable candidates. Moreover, this case demonstrates the necessity to remain vigilant in the interpretation of genetic results which are inconsistent with clinical features.
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Drosophila GPCR Han is a receptor for the circadian clock neuropeptide PDF.
Hyun, Seogang; Lee, Youngseok; Hong, Sung-Tae; Bang, Sunhoe; Paik, Donggi; Kang, Jongkyun; Shin, Jinwhan; Lee, Jaejung; Jeon, Keunhye; Hwang, Seungyoon; Bae, Eunkyung; Kim, Jaeseob
2005-10-20
The pigment-dispersing factor (PDF) is a neuropeptide controlling circadian behavioral rhythms in Drosophila, but its receptor is not yet known. From a large-scale temperature preference behavior screen in Drosophila, we isolated a P insertion mutant that preferred different temperatures during the day and night. This mutation, which we named han, reduced the transcript level of CG13758. We found that Han was expressed specifically in 13 pairs of circadian clock neurons in the adult brain. han null flies showed arrhythmic circadian behavior in constant darkness. The behavioral characteristics of han null mutants were similar to those of pdf null mutants. We also found that PDF binds specifically to S2 cells expressing Han, which results in the elevation of cAMP synthesis. Therefore, we herein propose that Han is a PDF receptor regulating circadian behavioral rhythm through coordination of activities of clock neurons.
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Reduction of aberrant NF-κB signalling ameliorates Rett syndrome phenotypes in Mecp2-null mice
Kishi, Noriyuki; MacDonald, Jessica L.; Ye, Julia; Molyneaux, Bradley J.; Azim, Eiman; Macklis, Jeffrey D.
2016-01-01
Mutations in the transcriptional regulator Mecp2 cause the severe X-linked neurodevelopmental disorder Rett syndrome (RTT). In this study, we investigate genes that function downstream of MeCP2 in cerebral cortex circuitry, and identify upregulation of Irak1, a central component of the NF-κB pathway. We show that overexpression of Irak1 mimics the reduced dendritic complexity of Mecp2-null cortical callosal projection neurons (CPN), and that NF-κB signalling is upregulated in the cortex with Mecp2 loss-of-function. Strikingly, we find that genetically reducing NF-κB signalling in Mecp2-null mice not only ameliorates CPN dendritic complexity but also substantially extends their normally shortened lifespan, indicating broader roles for NF-κB signalling in RTT pathogenesis. These results provide new insight into both the fundamental neurobiology of RTT, and potential therapeutic strategies via NF-κB pathway modulation. PMID:26821816
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Bryan, Anthony C; Rodeheffer, Matthew S; Wearn, Christopher M; Shadel, Gerald S
2002-01-01
Mitochondrial translation is largely membrane-associated in S. cerevisiae. Recently, we discovered that the matrix protein Nam1p binds the amino-terminal domain of yeast mtRNA polymerase to couple translation and/or RNA-processing events to transcription. To gain additional insight into these transcription-coupled processes, we performed a genetic screen for genes that suppress the petite phenotype of a point mutation in mtRNA polymerase (rpo41-R129D) when overexpressed. One suppressor identified in this screen was SLS1, which encodes a mitochondrial membrane protein required for assembly of respiratory-chain enzyme complexes III and IV. The mtRNA-processing defects associated with the rpo41-R129D mutation were corrected in the suppressed strain, linking Sls1p to a pathway that includes mtRNA polymerase and Nam1p. This was supported by the observation that SLS1 overexpression rescued the petite phenotype of a NAM1 null mutation. In contrast, overexpression of Nam1p did not rescue the petite phenotype of a SLS1 null mutation, indicating that Nam1p and Sls1p are not functionally redundant but rather exist in an ordered pathway. On the basis of these data, a model in which Nam1p coordinates the delivery of newly synthesized transcripts to the membrane, where Sls1p directs or regulates their subsequent handling by membrane-bound factors involved in translation, is proposed. PMID:11805046
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Domino, Steven E.; Karnak, David M.; Hurd, Elizabeth A.
2006-01-01
Background/Aims: Neoplasia-related alterations in cell surface α(1,2)fucosylated glycans have been reported in multiple tumors including colon, pancreas, endometrium, cervix, bladder, lung, and choriocarcinoma. Spontaneous colorectal tumors from mice with a germline null mutation of transforming growth factor-β signaling gene Smad3 (Madh3) were tested for α(1,2)fucosylated glycan expression. Methods: Ulex Europaeus Agglutinin-I lectin staining, fucosyltransferase gene northern blot analysis, and a cross of mutant mice with Fut2 and Smad3 germline mutations were performed. Results: Spontaneous colorectal tumors from Smad3 (-/-) homozygous null mice were found to express α(1,2)fucosylated glycans in an abnormal pattern compared to adjacent nonneoplastic colon. Northern blot analysis of α(1,2)fucosyltransferase genes Fut1 and Fut2 revealed that Fut2, but not Fut1, steady-state mRNA levels were significantly increased in tumors relative to adjacent normal colonic mucosa. Mutant mice with a Fut2-inactivating germline mutation were crossed with Smad3 targeted mice. In Smad3 (-/-)/Fut2 (-/-) double knock-out mice, UEA-I lectin staining was eliminated from colon and colon tumors, however, the number and size of tumors present by 24 weeks of age did not vary regardless of the Fut2 genotype. Conclusions: In this model of colorectal cancer, cell surface α(1,2)fucosylation does not affect development of colon tumors. PMID:17264540
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Ishikawa, Yoshihiro; Vranka, Janice A; Boudko, Sergei P; Pokidysheva, Elena; Mizuno, Kazunori; Zientek, Keith; Keene, Douglas R; Rashmir-Raven, Ann M; Nagata, Kazuhiro; Winand, Nena J; Bächinger, Hans Peter
2012-06-22
The rate-limiting step of folding of the collagen triple helix is catalyzed by cyclophilin B (CypB). The G6R mutation in cyclophilin B found in the American Quarter Horse leads to autosomal recessive hyperelastosis cutis, also known as hereditary equine regional dermal asthenia. The mutant protein shows small structural changes in the region of the mutation at the side opposite the catalytic domain of CypB. The peptidylprolyl cis-trans isomerase activity of the mutant CypB is normal when analyzed in vitro. However, the biosynthesis of type I collagen in affected horse fibroblasts shows a delay in folding and secretion and a decrease in hydroxylysine and glucosyl-galactosyl hydroxylysine. This leads to changes in the structure of collagen fibrils in tendon, similar to those observed in P3H1 null mice. In contrast to cyclophilin B null mice, where little 3-hydroxylation was found in type I collagen, 3-hydroxylation of type I collagen in affected horses is normal. The mutation disrupts the interaction of cyclophilin B with the P-domain of calreticulin, with lysyl hydroxylase 1, and probably other proteins, such as the formation of the P3H1·CypB·cartilage-associated protein complex, resulting in less effective catalysis of the rate-limiting step in collagen folding in the rough endoplasmic reticulum.
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Identification of a canine model of pyruvate dehydrogenase phosphatase 1 deficiency.
Cameron, Jessie M; Maj, Mary C; Levandovskiy, Valeriy; MacKay, Neviana; Shelton, G Diane; Robinson, Brian H
2007-01-01
Exercise intolerance syndromes are well known to be associated with inborn errors of metabolism affecting glycolysis (phosphorylase and phosphofructokinase deficiency) and fatty acid oxidation (palmitoyl carnitine transferase deficiency). We have identified a canine model for profound exercise intolerance caused by a deficit in PDP1 (EC 3.1.3.43), the phosphatase enzyme that activates the pyruvate dehydrogenase complex (PDHc). The Clumber spaniel breed was originated in 1760 by the Duc de Noailles, as a hunting dog with a gentle temperament suitable for the 'elderly gentleman'. Here we report that 20% of the current Clumber and Sussex spaniel population are carriers for a null mutation in PDP1, and that homozygosity produces severe exercise intolerance. Human pyruvate dehydrogenase phosphatase deficiency was recently characterized at the molecular level. However, the nature of the human mutation (loss of a single amino acid altering PDP1 activity) made it impossible to discern the role of the second phosphatase isoform, PDP2, in the deficient phenotype. Here we show that the null mutation in dogs provides a valuable animal model with which to study the effects of dysregulation of the PDHc. Knowledge of the molecular defect has allowed for the institution of a rapid restriction enzyme test for the canine mutation that will allow for selective breeding and has led to a suggested dietary therapy for affected dogs that has proven to be beneficial. Pharmacological and genetic therapies for PDP1 deficiency can now be investigated and the role of PDP2 can be fully characterized.
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Ishikawa, Yoshihiro; Vranka, Janice A.; Boudko, Sergei P.; Pokidysheva, Elena; Mizuno, Kazunori; Zientek, Keith; Keene, Douglas R.; Rashmir-Raven, Ann M.; Nagata, Kazuhiro; Winand, Nena J.; Bächinger, Hans Peter
2012-01-01
The rate-limiting step of folding of the collagen triple helix is catalyzed by cyclophilin B (CypB). The G6R mutation in cyclophilin B found in the American Quarter Horse leads to autosomal recessive hyperelastosis cutis, also known as hereditary equine regional dermal asthenia. The mutant protein shows small structural changes in the region of the mutation at the side opposite the catalytic domain of CypB. The peptidylprolyl cis-trans isomerase activity of the mutant CypB is normal when analyzed in vitro. However, the biosynthesis of type I collagen in affected horse fibroblasts shows a delay in folding and secretion and a decrease in hydroxylysine and glucosyl-galactosyl hydroxylysine. This leads to changes in the structure of collagen fibrils in tendon, similar to those observed in P3H1 null mice. In contrast to cyclophilin B null mice, where little 3-hydroxylation was found in type I collagen, 3-hydroxylation of type I collagen in affected horses is normal. The mutation disrupts the interaction of cyclophilin B with the P-domain of calreticulin, with lysyl hydroxylase 1, and probably other proteins, such as the formation of the P3H1·CypB·cartilage-associated protein complex, resulting in less effective catalysis of the rate-limiting step in collagen folding in the rough endoplasmic reticulum. PMID:22556420
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Cunningham, Steven C; Gallmeier, Eike; Hucl, Tomas; Dezentje, David A; Calhoun, Eric S; Falco, Geppino; Abdelmohsen, Kotb; Gorospe, Myriam; Kern, Scott E
2006-06-01
Tumor-suppressors have commanded attention due to the selection for their inactivating mutations in human tumors. However, relatively little is understood about the inverse, namely, that tumors do not select for a large proportion of seemingly favorable mutations in tumor-suppressor genes. This could be explained by a detrimental phenotype accruing in a cell type-specific manner to most cells experiencing a biallelic loss. For example, MKK4, a tumor suppressor gene distinguished by a remarkably consistent mutational rate across diverse tumor types and an unusually high rate of loss of heterozygosity, has the surprisingly low rate of genetic inactivation of only approximately 5%. To explore this incongruity, we engineered a somatic gene knockout of MKK4 in human cancer cells. Although the null cells resembled the wild-type cells regarding in vitro viability and proliferation in plastic dishes, there was a marked difference in a more relevant in vivo model of experimental metastasis and tumorigenesis. MKK4(-/-) clones injected i.v. produced fewer lung metastases than syngeneic MKK4-competent cells (P = 0.0034). These findings show how cell type-specific detrimental phenotypes can offer a paradoxical and yet key counterweight to the selective advantage attained by cells as they experiment with genetic null states during tumorigenesis, the resultant balance then determining the observed biallelic mutation rate for a given tumor-suppressor gene.
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A novel method for objective vision testing in canine models of inherited retinal disease.
Gearhart, Patricia M; Gearhart, Chris C; Petersen-Jones, Simon M
2008-08-01
The use of canine models of retinal disease in the development of therapeutic strategies for inherited retinal disorders is a growing area of research. To evaluate accurately the success of potential vision-enhancing treatments, reliable methods for objectively assessing visual function in canine models is necessary. A simple vision-testing device was constructed that consisted of a junction box with four exit tunnels. Dogs were placed in the junction box and given one vision-based choice for exit. The first-choice tunnel and time to exit were recorded and analyzed. Two canine models of retinal disease with distinct molecular defects, a null mutation in the gene encoding the alpha subunit of rod cyclic GMP phosphodiesterase (PDE6A), and a null mutation in the gene encoding a retinal pigment epithelium-specific protein (RPE65) were tested and compared to those in unaffected dogs. With the use of bright light versus dim red light, the test differentiated between unaffected dogs and dogs affected with either mutation with a high degree of certainty. The white-light intensity series showed a significantly different performance between the unaffected and affected dogs. A significant difference in performance was detected between the dogs with each mutation. The results indicate that this novel canine vision-testing method is an accurate and sensitive means of distinguishing between unaffected dogs and dogs affected with two different forms of inherited retinal disease and should be useful as a means of assessing response to therapy in future studies.
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Pippucci, Tommaso; Maresca, Alessandra; Magini, Pamela; Cenacchi, Giovanna; Donadio, Vincenzo; Palombo, Flavia; Papa, Valentina; Incensi, Alex; Gasparre, Giuseppe; Valentino, Maria Lucia; Preziuso, Carmela; Pisano, Annalinda; Ragno, Michele; Liguori, Rocco; Giordano, Carla; Tonon, Caterina; Lodi, Raffaele; Parmeggiani, Antonia; Carelli, Valerio; Seri, Marco
2015-06-01
Notch signaling is essential for vascular physiology. Neomorphic heterozygous mutations in NOTCH3, one of the four human NOTCH receptors, cause cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Hypomorphic heterozygous alleles have been occasionally described in association with a spectrum of cerebrovascular phenotypes overlapping CADASIL, but their pathogenic potential is unclear. We describe a patient with childhood-onset arteriopathy, cavitating leukoencephalopathy with cerebral white matter abnormalities presented as diffuse cavitations, multiple lacunar infarctions and disseminated microbleeds. We identified a novel homozygous c.C2898A (p.C966*) null mutation in NOTCH3 abolishing NOTCH3 expression and causing NOTCH3 signaling impairment. NOTCH3 targets acting in the regulation of arterial tone (KCNA5) or expressed in the vasculature (CDH6) were downregulated. Patient's vessels were characterized by smooth muscle degeneration as in CADASIL, but without deposition of granular osmiophilic material (GOM), the CADASIL hallmark. The heterozygous parents displayed similar but less dramatic trends in decrease in the expression of NOTCH3 and its targets, as well as in vessel degeneration. This study suggests a functional link between NOTCH3 deficiency and pathogenesis of vascular leukoencephalopathies. © 2015 The Authors. Published under the terms of the CC BY 4.0 license.
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Bit-1 is an essential regulator of myogenic differentiation
Griffiths, Genevieve S.; Doe, Jinger; Jijiwa, Mayumi; Van Ry, Pam; Cruz, Vivian; de la Vega, Michelle; Ramos, Joe W.; Burkin, Dean J.; Matter, Michelle L.
2015-01-01
Muscle differentiation requires a complex signaling cascade that leads to the production of multinucleated myofibers. Genes regulating the intrinsic mitochondrial apoptotic pathway also function in controlling cell differentiation. How such signaling pathways are regulated during differentiation is not fully understood. Bit-1 (also known as PTRH2) mutations in humans cause infantile-onset multisystem disease with muscle weakness. We demonstrate here that Bit-1 controls skeletal myogenesis through a caspase-mediated signaling pathway. Bit-1-null mice exhibit a myopathy with hypotrophic myofibers. Bit-1-null myoblasts prematurely express muscle-specific proteins. Similarly, knockdown of Bit-1 expression in C2C12 myoblasts promotes early differentiation, whereas overexpression delays differentiation. In wild-type mice, Bit-1 levels increase during differentiation. Bit-1-null myoblasts exhibited increased levels of caspase 9 and caspase 3 without increased apoptosis. Bit-1 re-expression partially rescued differentiation. In Bit-1-null muscle, Bcl-2 levels are reduced, suggesting that Bcl-2-mediated inhibition of caspase 9 and caspase 3 is decreased. Bcl-2 re-expression rescued Bit-1-mediated early differentiation in Bit-1-null myoblasts and C2C12 cells with knockdown of Bit-1 expression. These results support an unanticipated yet essential role for Bit-1 in controlling myogenesis through regulation of Bcl-2. PMID:25770104
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Identification of the sequence variations of 15 autosomal STR loci in a Chinese population.
Chen, Wenjing; Cheng, Jianding; Ou, Xueling; Chen, Yong; Tong, Dayue; Sun, Hongyu
2014-01-01
DNA sequence variation including base(s) changes and insertion or deletion in the primer binding region may cause a null allele and, if this changes the length of the amplified fragment out of the allelic ladder, off-ladder (OL) alleles may be detected. In order to provide accurate and reliable DNA evidence for forensic DNA analysis, it is essential to clarify sequence variations in prevalently used STR loci. Suspected null alleles and OL alleles of PlowerPlex16® System from 21,934 unrelated Chinese individuals were verified by alternative systems and sequenced. A total of 17 cases with null alleles were identified, including 12 kinds of point mutations in 16 cases and a 19-base deletion in one case. The total frequency of null alleles was 7.751 × 10(-4). Eight hundred and forty-four OL alleles classified as being of 97 different kinds were observed at 15 STR loci of the PowerPlex®16 system except vWA. All the frequencies of OL alleles were under 0.01. Null alleles should be confirmed by alternative primers and OL alleles should be named appropriately. Particular attention should be paid to sequence variation, since incorrect designation could lead to false conclusions.
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The Essential Gene EMB1611 Maintains Shoot Apical Meristem Function During Arabidopsis Development
USDA-ARS?s Scientific Manuscript database
The Arabidopsis thaliana genome contains hundreds of genes essential for seed development. Because null mutations in these genes cause embryo lethality, their specific molecular and developmental functions are largely unknown. Here, we identify a role for EMB1611/MEE22, an essential gene in Arabidop...
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Disruptions in AUX1-dependent auxin influx alter hypocotyl phototropism in Arabidopsis.
Stone, Bethany B; Stowe-Evans, Emily L; Harper, Reneé M; Celaya, R Brandon; Ljung, Karin; Sandberg, Göran; Liscum, Emmanuel
2008-01-01
Phototropism represents a differential growth response by which plant organs can respond adaptively to changes in the direction of incident light to optimize leaf/stem positioning for photosynthetic light capture and root growth orientation for water/nutrient acquisition. Studies over the past few years have identified a number of components in the signaling pathway(s) leading to development of phototropic curvatures in hypocotyls. These include the phototropin photoreceptors (phot1 and phot2) that perceive directional blue-light (BL) cues and then stimulate signaling, leading to relocalization of the plant hormone auxin, as well as the auxin response factor NPH4/ARF7 that responds to changes in local auxin concentrations to directly mediate expression of genes likely encoding proteins necessary for development of phototropic curvatures. While null mutations in NPH4/ARF7 condition an aphototropic response to unidirectional BL, seedlings carrying the same mutations recover BL-dependent phototropic responsiveness if co-irradiated with red light (RL) or pre-treated with either ethylene. In the present study, we identify second-site enhancer mutations in the nph4 background that abrogate these recovery responses. One of these mutations--map1 (modifier of arf7 phenotypes 1)--was found to represent a missense allele of AUX1--a gene encoding a high-affinity auxin influx carrier previously associated with a number of root responses. Pharmacological studies and analyses of additional aux1 mutants confirmed that AUX1 functions as a modulator of hypocotyl phototropism. Moreover, we have found that the strength of dependence of hypocotyl phototropism on AUX1-mediated auxin influx is directly related to the auxin responsiveness of the seedling in question.
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Haire, Shannon E; Aleman, Tomas S; Cideciyan, Artur V; Sokal, Izabel; Palczewski, Krzysztof; Jacobson, Samuel G; Semple-Rowland, Susan L
2006-01-01
Background Leber congenital amaurosis (LCA) is a genetically heterogeneous group of retinal diseases that cause congenital blindness in infants and children. Mutations in the GUCY2D gene that encodes retinal guanylate cyclase–1 (retGC1) were the first to be linked to this disease group (LCA type 1 [LCA1]) and account for 10%–20% of LCA cases. These mutations disrupt synthesis of cGMP in photoreceptor cells, a key second messenger required for function of these cells. The GUCY1*B chicken, which carries a null mutation in the retGC1 gene, is blind at hatching and serves as an animal model for the study of LCA1 pathology and potential treatments in humans. Methods and Findings A lentivirus-based gene transfer vector carrying the GUCY2D gene was developed and injected into early-stage GUCY1*B embryos to determine if photoreceptor function and sight could be restored to these animals. Like human LCA1, the avian disease shows early-onset blindness, but there is a window of opportunity for intervention. In both diseases there is a period of photoreceptor cell dysfunction that precedes retinal degeneration. Of seven treated animals, six exhibited sight as evidenced by robust optokinetic and volitional visual behaviors. Electroretinographic responses, absent in untreated animals, were partially restored in treated animals. Morphological analyses indicated there was slowing of the retinal degeneration. Conclusions Blindness associated with loss of function of retGC1 in the GUCY1*B avian model of LCA1 can be reversed using viral vector-mediated gene transfer. Furthermore, this reversal can be achieved by restoring function to a relatively low percentage of retinal photoreceptors. These results represent a first step toward development of gene therapies for one of the more common forms of childhood blindness. PMID:16700630
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An Agrobacterium-delivered CRISPR/Cas9 system for high-frequency targeted mutagenesis in maize.
Char, Si Nian; Neelakandan, Anjanasree K; Nahampun, Hartinio; Frame, Bronwyn; Main, Marcy; Spalding, Martin H; Becraft, Philip W; Meyers, Blake C; Walbot, Virginia; Wang, Kan; Yang, Bing
2017-02-01
CRISPR/Cas9 is a powerful genome editing tool in many organisms, including a number of monocots and dicots. Although the design and application of CRISPR/Cas9 is simpler compared to other nuclease-based genome editing tools, optimization requires the consideration of the DNA delivery and tissue regeneration methods for a particular species to achieve accuracy and efficiency. Here, we describe a public sector system, ISU Maize CRISPR, utilizing Agrobacterium-delivered CRISPR/Cas9 for high-frequency targeted mutagenesis in maize. This system consists of an Escherichia coli cloning vector and an Agrobacterium binary vector. It can be used to clone up to four guide RNAs for single or multiplex gene targeting. We evaluated this system for its mutagenesis frequency and heritability using four maize genes in two duplicated pairs: Argonaute 18 (ZmAgo18a and ZmAgo18b) and dihydroflavonol 4-reductase or anthocyaninless genes (a1 and a4). T 0 transgenic events carrying mono- or diallelic mutations of one locus and various combinations of allelic mutations of two loci occurred at rates over 70% mutants per transgenic events in both Hi-II and B104 genotypes. Through genetic segregation, null segregants carrying only the desired mutant alleles without the CRISPR transgene could be generated in T 1 progeny. Inheritance of an active CRISPR/Cas9 transgene leads to additional target-specific mutations in subsequent generations. Duplex infection of immature embryos by mixing two individual Agrobacterium strains harbouring different Cas9/gRNA modules can be performed for improved cost efficiency. Together, the findings demonstrate that the ISU Maize CRISPR platform is an effective and robust tool to targeted mutagenesis in maize. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
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Kohan, Romina; Noelia Carabelos, María; Xin, Winnie; Sims, Katherine; Guelbert, Norberto; Adriana Cismondi, Inés; Pons, Patricia; Alonso, Graciela Irene; Troncoso, Mónica; Witting, Scarlet; Pearce, David A.; de Kremer, Raquel Dodelson; Oller-Ramírez, Ana María; de Halac, Inés Noher
2013-01-01
Tripeptidyl-peptidase 1 (TPP1) null or residual activity occurs in neuronal ceroid lipofuscinosis (NCL) with underlying TPP1/CLN2 mutations. A survey of 25 South American CLN2 affected individuals enabled the differentiation of two phenotypes: classical late-infantile and variant juvenile, each in approximately 50% of patients, with residual TPP1 activity occurring in approximately 32%. Each individual was assigned to one of three subgroups: (I) n=11, null TPP1 activity in leukocytes; (II) n=8, residual TPP1 activity of 0.60–15.85 nmol/h/mg (nr 110–476); (III) n=6, activity not measured in leukocytes. Curvilinear bodies (CB) appeared in almost all studied CLN2 subjects; the only exceptions occurred in cases of subgroup II: two individuals had combined CBs/fingerprints (FPs), and one case had pure FPs. There were 15 mutations (4 first published in this paper, 3 previously observed in South America by our group, and 8 previously observed by others). In subgroup I, mutations were either missense or nonsense; in subgroups II and III, mutations prevailed at the non-conserved intronic site, c.887-10A>G (intron 7), and to a lesser extent at c.89+5G>C (intron 2), in heterozygous combinations. Grouping phenotypically and genetically known individuals on the basis of TPP1 activity supported the concept that residual enzyme activity underlies a protracted disease course. The prevalence of intronic mutations at nonconserved sites in subgroup II individuals indicates that some alternative splicing might allow some residual TPP1 activity. PMID:23266810
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Prolonged Stationary-Phase Incubation Selects for lrp Mutations in Escherichia coli K-12
Zinser, Erik R.; Kolter, Roberto
2000-01-01
Evolution by natural selection occurs in cultures of Escherichia coli maintained under carbon starvation stress. Mutants of increased fitness express a growth advantage in stationary phase (GASP) phenotype, enabling them to grow and displace the parent as the majority population. The first GASP mutation was identified as a loss-of-function allele of rpoS, encoding the stationary-phase global regulator, ςS (M. M. Zambrano, D. A. Siegele, M. A. Almirón, A. Tormo, and R. Kolter, Science 259:1757–1760, 1993). We now report that a second global regulator, Lrp, can also play a role in stationary-phase competition. We found that a mutant that took over an aged culture of an rpoS strain had acquired a GASP mutation in lrp. This GASP allele, lrp-1141, encodes a mutant protein lacking the critical glycine in the turn of the helix-turn-helix DNA-binding domain. The lrp-1141 allele behaves as a null mutation when in single copy and is dominant negative when overexpressed. Hence, the mutant protein appears to retain stability and the ability to dimerize but lacks DNA-binding activity. We also demonstrated that a lrp null allele generated by a transposon insertion has a fitness gain identical to that of the lrp-1141 allele, verifying that cells lacking Lrp activity have a competitive advantage during prolonged starvation. Finally, we tested by genetic analysis the hypothesis that the lrp-1141 GASP mutation confers a fitness gain by enhancing amino acid catabolism during carbon starvation. We found that while amino acid catabolism may play a role, it is not necessary for the lrp GASP phenotype, and hence the lrp GASP phenotype is due to more global physiological changes. PMID:10894750
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[Programmed mouse genome modifications].
Babinet, C
1998-02-01
The availability, in the mouse, of embryonic stem cells (ES cells) which have the ability to colonize the germ line of a developing embryo, has opened entirely new avenues to the genetic approach of embryonic development, physiology and pathology of this animal. Indeed, it is now possible, using homologous recombination in ES cells, to introduce mutations in any gene as long as it has been cloned. Thus, null as well as more subtle mutations can be created. Furthermore, scenarios are currently being derived which will allow one to generate conditional mutations. Taken together, these methods offer a tremendous tool to study gene function in vivo; they also open the way to creating murine models of human genetic diseases.
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Kroken, Abby R.; Chen, Camille K.; Evans, David J.; Yahr, Timothy L.
2018-01-01
ABSTRACT Pseudomonas aeruginosa is internalized into multiple types of epithelial cell in vitro and in vivo and yet is often regarded as an exclusively extracellular pathogen. Paradoxically, ExoS, a type three secretion system (T3SS) effector, has antiphagocytic activities but is required for intracellular survival of P. aeruginosa and its occupation of bleb niches in epithelial cells. Here, we addressed mechanisms for this dichotomy using invasive (ExoS-expressing) P. aeruginosa and corresponding effector-null isogenic T3SS mutants, effector-null mutants of cytotoxic P. aeruginosa with and without ExoS transformation, antibiotic exclusion assays, and imaging using a T3SS-GFP reporter. Except for effector-null PA103, all strains were internalized while encoding ExoS. Intracellular bacteria showed T3SS activation that continued in replicating daughter cells. Correcting the fleQ mutation in effector-null PA103 promoted internalization by >10-fold with or without ExoS. Conversely, mutating fleQ in PAO1 reduced internalization by >10-fold, also with or without ExoS. Effector-null PA103 remained less well internalized than PAO1 matched for fleQ status, but only with ExoS expression, suggesting additional differences between these strains. Quantifying T3SS activation using GFP fluorescence and quantitative reverse transcription-PCR (qRT-PCR) showed that T3SS expression was hyperinducible for strain PA103ΔexoUT versus other isolates and was unrelated to fleQ status. These findings support the principle that P. aeruginosa is not exclusively an extracellular pathogen, with internalization influenced by the relative proportions of T3SS-positive and T3SS-negative bacteria in the population during host cell interaction. These data also challenge current thinking about T3SS effector delivery into host cells and suggest that T3SS bistability is an important consideration in studying P. aeruginosa pathogenesis. PMID:29717012
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NDST1 missense mutations in autosomal recessive intellectual disability.
Reuter, Miriam S; Musante, Luciana; Hu, Hao; Diederich, Stefan; Sticht, Heinrich; Ekici, Arif B; Uebe, Steffen; Wienker, Thomas F; Bartsch, Oliver; Zechner, Ulrich; Oppitz, Cornelia; Keleman, Krystyna; Jamra, Rami Abou; Najmabadi, Hossein; Schweiger, Susann; Reis, André; Kahrizi, Kimia
2014-11-01
NDST1 was recently proposed as a candidate gene for autosomal recessive intellectual disability in two families. It encodes a bifunctional GlcNAc N-deacetylase/N-sulfotransferase with important functions in heparan sulfate biosynthesis. In mice, Ndst1 is crucial for embryonic development and homozygous null mutations are perinatally lethal. We now report on two additional unrelated families with homozygous missense NDST1 mutations. All mutations described to date predict the substitution of conserved amino acids in the sulfotransferase domain, and mutation modeling predicts drastic alterations in the local protein conformation. Comparing the four families, we noticed significant overlap in the clinical features, including both demonstrated and apparent intellectual disability, muscular hypotonia, epilepsy, and postnatal growth deficiency. Furthermore, in Drosophila, knockdown of sulfateless, the NDST ortholog, impairs long-term memory, highlighting its function in cognition. Our data confirm NDST1 mutations as a cause of autosomal recessive intellectual disability with a distinctive phenotype, and support an important function of NDST1 in human development. © 2014 Wiley Periodicals, Inc.
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Kaniak-Golik, Aneta; Kuberska, Renata; Dzierzbicki, Piotr; Sledziewska-Gojska, Ewa
2017-01-01
Rad27/FEN1 nuclease that plays important roles in the maintenance of DNA stability in the nucleus has recently been shown to reside in mitochondria. Accordingly, it has been established that Rad27 deficiency causes increased mutagenesis, but decreased microsatellite instability and homologous recombination in mitochondria. Our current analysis of mutations leading to erythromycin resistance indicates that only some of them arise in mitochondrial DNA and that the GC→AT transition is a hallmark of the mitochondrial mutagenesis in rad27 null background. We also show that the mitochondrial mutator phenotype resulting from Rad27 deficiency entirely depends on the DNA damage checkpoint kinase Dun1. DUN1 inactivation suppresses the mitochondrial mutator phenotype caused by Rad27 deficiency and this suppression is eliminated at least in part by subsequent deletion of SML1 encoding a repressor of ribonucleotide reductase. We conclude that Rad27 deficiency causes a mitochondrial mutator phenotype via activation of DNA damage checkpoint kinase Dun1 and that a Dun1-mediated increase of dNTP pools contributes to this phenomenon. These results point to the nuclear DNA instability as the source of mitochondrial mutagenesis. Consistently, we show that mitochondrial mutations occurring more frequently in yeast devoid of Rrm3, a DNA helicase involved in rDNA replication, are also dependent on Dun1. In addition, we have established that overproduction of Exo1, which suppresses DNA damage sensitivity and replication stress in nuclei of Rad27 deficient cells, but does not enter mitochondria, suppresses the mitochondrial mutagenesis. Exo1 overproduction restores also a great part of allelic recombination and microsatellite instability in mitochondria of Rad27 deficient cells. In contrast, the overproduction of Exo1 does not influence mitochondrial direct-repeat mediated deletions in rad27 null background, pointing to this homologous recombination pathway as the direct target of Rad27 activity in mitochondria.
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Dzierzbicki, Piotr
2017-01-01
Rad27/FEN1 nuclease that plays important roles in the maintenance of DNA stability in the nucleus has recently been shown to reside in mitochondria. Accordingly, it has been established that Rad27 deficiency causes increased mutagenesis, but decreased microsatellite instability and homologous recombination in mitochondria. Our current analysis of mutations leading to erythromycin resistance indicates that only some of them arise in mitochondrial DNA and that the GC→AT transition is a hallmark of the mitochondrial mutagenesis in rad27 null background. We also show that the mitochondrial mutator phenotype resulting from Rad27 deficiency entirely depends on the DNA damage checkpoint kinase Dun1. DUN1 inactivation suppresses the mitochondrial mutator phenotype caused by Rad27 deficiency and this suppression is eliminated at least in part by subsequent deletion of SML1 encoding a repressor of ribonucleotide reductase. We conclude that Rad27 deficiency causes a mitochondrial mutator phenotype via activation of DNA damage checkpoint kinase Dun1 and that a Dun1-mediated increase of dNTP pools contributes to this phenomenon. These results point to the nuclear DNA instability as the source of mitochondrial mutagenesis. Consistently, we show that mitochondrial mutations occurring more frequently in yeast devoid of Rrm3, a DNA helicase involved in rDNA replication, are also dependent on Dun1. In addition, we have established that overproduction of Exo1, which suppresses DNA damage sensitivity and replication stress in nuclei of Rad27 deficient cells, but does not enter mitochondria, suppresses the mitochondrial mutagenesis. Exo1 overproduction restores also a great part of allelic recombination and microsatellite instability in mitochondria of Rad27 deficient cells. In contrast, the overproduction of Exo1 does not influence mitochondrial direct-repeat mediated deletions in rad27 null background, pointing to this homologous recombination pathway as the direct target of Rad27 activity in mitochondria. PMID:28678842
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Altmann, Helene M; Tester, David J; Will, Melissa L; Middha, Sumit; Evans, Jared M; Eckloff, Bruce W; Ackerman, Michael J
2015-06-09
Long-QT syndrome (LQTS) may result in syncope, seizures, or sudden cardiac arrest. Although 16 LQTS-susceptibility genes have been discovered, 20% to 25% of LQTS remains genetically elusive. We performed whole-exome sequencing child-parent trio analysis followed by recessive and sporadic inheritance modeling and disease-network candidate analysis gene ranking to identify a novel underlying genetic mechanism for LQTS. Subsequent mutational analysis of the candidate gene was performed with polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing on a cohort of 33 additional unrelated patients with genetically elusive LQTS. After whole-exome sequencing and variant filtration, a homozygous p.D18fs*13 TRDN-encoded triadin frameshift mutation was discovered in a 10-year-old female patient with LQTS with a QTc of 500 milliseconds who experienced recurrent exertion-induced syncope/cardiac arrest beginning at 1 year of age. Subsequent mutational analysis of TRDN revealed either homozygous or compound heterozygous frameshift mutations in 4 of 33 unrelated cases of LQTS (12%). All 5 TRDN-null patients displayed extensive T-wave inversions in precordial leads V1 through V4, with either persistent or transient QT prolongation and severe disease expression of exercise-induced cardiac arrest in early childhood (≤3 years of age) and required aggressive therapy. The overall yield of TRDN mutations was significantly greater in patients ≤10 years of age (5 of 10, 50%) compared with older patients (0 of 24, 0%; P=0.0009). We identified TRDN as a novel underlying genetic basis for recessively inherited LQTS. All TRDN-null patients had strikingly similar phenotypes. Given the recurrent nature of potential lethal arrhythmias, patients fitting this phenotypic profile should undergo cardiac TRDN genetic testing. © 2015 American Heart Association, Inc.
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Wang, Tao; Stadler, Zsofia K; Zhang, Liying; Weiser, Martin R; Basturk, Olca; Hechtman, Jaclyn F; Vakiani, Efsevia; Saltz, Lenard B; Klimstra, David S; Shia, Jinru
2018-04-01
Microsatellite instability, a well-established driver pathway in colorectal carcinogenesis, can develop in both sporadic and hereditary conditions via different molecular alterations in the DNA mismatch repair (MMR) genes. MMR protein immunohistochemistry (IHC) is currently widely used for the detection of MMR deficiency in solid tumors. The IHC test, however, can show varied staining patterns, posing challenges in the interpretation of the staining results in some cases. Here we report a case of an 80-year-old female with a colonic adenocarcinoma that exhibited an unusual "null" IHC staining pattern with complete loss of all four MMR proteins (MLH1, MSH2, MSH6, and PMS2). This led to subsequent MLH1 methylation testing and next generation sequencing which demonstrated that the loss of all MMR proteins was associated with concurrent promoter hypermethylation of MLH1 and double somatic truncating mutations in MSH2. These molecular findings, in conjunction with the patient's age being 80 years and the fact that the patient had no personal or family cancer history, indicated that the MMR deficiency was highly likely sporadic in nature. Thus, the stringent Lynch syndrome type surveillance programs were not recommended to the patient and her family members. This case illustrates a rare but important scenario where a null IHC phenotype signifies complex underlying molecular alternations that bear clinical management implications, highlighting the need for recognition and awareness of such unusual IHC staining patterns.
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Pederick, Daniel T.; Homan, Claire C.; Jaehne, Emily J.; Piltz, Sandra G.; Haines, Bryan P.; Baune, Bernhard T.; Jolly, Lachlan A.; Hughes, James N.; Gecz, Jozef; Thomas, Paul Q.
2016-01-01
Protocadherin 19 (Pcdh19) is an X-linked gene belonging to the protocadherin superfamily, whose members are predominantly expressed in the central nervous system and have been implicated in cell-cell adhesion, axon guidance and dendrite self-avoidance. Heterozygous loss-of-function mutations in humans result in the childhood epilepsy disorder PCDH19 Girls Clustering Epilepsy (PCDH19 GCE) indicating that PCDH19 is required for brain development. However, understanding PCDH19 function in vivo has proven challenging and has not been studied in mammalian models. Here, we validate a murine Pcdh19 null allele in which a β-Geo reporter cassette is expressed under the control of the endogenous promoter. Analysis of β-Geo reporter activity revealed widespread but restricted expression of PCDH19 in embryonic, postnatal and adult brains. No gross morphological defects were identified in Pcdh19+/β-Geo and Pcdh19Y/β-Geo brains and the location of Pcdh19 null cells was normal. However, in vitro migration assays revealed that the motility of Pcdh19 null neurons was significantly elevated, potentially contributing to pathogenesis in patients with PCDH19 mutations. Overall our initial characterization of Pcdh19+/β-Geo, Pcdh19β-Geo/β-Geo and Pcdh19Y/β-Geomice reveals that despite widespread expression of Pcdh19 in the CNS, and its role in human epilepsy, its function in mice is not essential for brain development. PMID:27240640
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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...
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Little, John B.; Kato, Takamitsu A.; Shih, Hung-Ying; Xie, Xian-Jin; Wilson Jr., Paul F.; Brogan, John R.; Kurimasa, Akihiro; Chen, David J.; Bedford, Joel S.; Chen, Benjamin P. C.
2014-01-01
We have examined cell-cycle dependence of chromosomal aberration induction and cell killing after high or low dose-rate γ irradiation in cells bearing DNA-PKcs mutations in the S2056 cluster, the T2609 cluster, or the kinase domain. We also compared sister chromatid exchanges (SCE) production by very low fluences of α-particles in DNA-PKcs mutant cells, and in homologous recombination repair (HRR) mutant cells including Rad51C, Rad51D, and Fancg/xrcc9. Generally, chromosomal aberrations and cell killing by γ-rays were similarly affected by mutations in DNA-PKcs, and these mutant cells were more sensitive in G1 than in S/G2 phase. In G1-irradiated DNA-PKcs mutant cells, both chromosome- and chromatid-type breaks and exchanges were in excess than wild-type cells. For cells irradiated in late S/G2 phase, mutant cells showed very high yields of chromatid breaks compared to wild-type cells. Few exchanges were seen in DNA-PKcs-null, Ku80-null, or DNA-PKcs kinase dead mutants, but exchanges in excess were detected in the S2506 or T2609 cluster mutants. SCE induction by very low doses of α-particles is resulted from bystander effects in cells not traversed by α-particles. SCE seen in wild-type cells was completely abolished in Rad51C- or Rad51D-deficient cells, but near normal in Fancg/xrcc9 cells. In marked contrast, very high levels of SCEs were observed in DNA-PKcs-null, DNA-PKcs kinase-dead and Ku80-null mutants. SCE induction was also abolished in T2609 cluster mutant cells, but was only slightly reduced in the S2056 cluster mutant cells. Since both non-homologous end-joining (NHEJ) and HRR systems utilize initial DNA lesions as a substrate, these results suggest the possibility of a competitive interference phenomenon operating between NHEJ and at least the Rad51C/D components of HRR; the level of interaction between damaged DNA and a particular DNA-PK component may determine the level of interaction of such DNA with a relevant HRR component. PMID:24714417
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Efficient Plastid Transformation in Arabidopsis.
Yu, Qiguo; Lutz, Kerry Ann; Maliga, Pal
2017-09-01
Plastid transformation is routine in tobacco ( Nicotiana tabacum ) but 100-fold less frequent in Arabidopsis ( Arabidopsis thaliana ), preventing its use in plastid biology. A recent study revealed that null mutations in ACC2 , encoding a plastid-targeted acetyl-coenzyme A carboxylase, cause hypersensitivity to spectinomycin. We hypothesized that plastid transformation efficiency should increase in the acc2 background, because when ACC2 is absent, fatty acid biosynthesis becomes dependent on translation of the plastid-encoded ACC β-carboxylase subunit. We bombarded ACC2 -defective Arabidopsis leaves with a vector carrying a selectable spectinomycin resistance ( aadA ) gene and gfp , encoding the green fluorescence protein GFP. Spectinomycin-resistant clones were identified as green cell clusters on a spectinomycin medium. Plastid transformation was confirmed by GFP accumulation from the second open reading frame of a polycistronic messenger RNA, which would not be translated in the cytoplasm. We obtained one to two plastid transformation events per bombarded sample in spectinomycin-hypersensitive Slavice and Columbia acc2 knockout backgrounds, an approximately 100-fold enhanced plastid transformation frequency. Slavice and Columbia are accessions in which plant regeneration is uncharacterized or difficult to obtain. A practical system for Arabidopsis plastid transformation will be obtained by creating an ACC2 null background in a regenerable Arabidopsis accession. The recognition that the duplicated ACCase in Arabidopsis is an impediment to plastid transformation provides a rational template to implement plastid transformation in related recalcitrant crops. © 2017 American Society of Plant Biologists. All Rights Reserved.
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Coffee, Erin M; Yerkes, Laura; Ewen, Elizabeth P; Zee, Tiffany; Tolan, Dean R
2010-02-01
Mutations in the aldolase B gene (ALDOB) impairing enzyme activity toward fructose-1-phosphate cleavage cause hereditary fructose intolerance (HFI). Diagnosis of the disease is possible by identifying known mutant ALDOB alleles in suspected patients; however, the frequencies of mutant alleles can differ by population. Here, 153 American HFI patients with 268 independent alleles were analyzed to identify the prevalence of seven known HFI-causing alleles (A149P, A174D, N334K, Delta4E4, R59Op, A337V, and L256P) in this population. Allele-specific oligonucleotide hybridization analysis was performed on polymerase chain reaction (PCR)-amplified genomic DNA from these patients. In the American population, the missense mutations A149P and A174D are the two most common alleles, with frequencies of 44% and 9%, respectively. In addition, the nonsense mutations Delta4E4 and R59Op are the next most common alleles, with each having a frequency of 4%. Together, the frequencies of all seven alleles make up 65% of HFI-causing alleles in this population. Worldwide, these same alleles make up 82% of HFI-causing mutations. This difference indicates that screening for common HFI alleles is more difficult in the American population. Nevertheless, a genetic screen for diagnosing HFI in America can be improved by including all seven alleles studied here. Lastly, identification of HFI patients presenting with classic symptoms and who have homozygous null genotypes indicates that aldolase B is not required for proper development or metabolic maintenance.
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Alanine scan of core positions in ubiquitin reveals links between dynamics, stability, and function
Lee, Shirley Y.; Pullen, Lester; Virgil, Daniel J.; Castañeda, Carlos A.; Abeykoon, Dulith; Bolon, Daniel N. A.; Fushman, David
2014-01-01
Mutations at solvent inaccessible core positions in proteins can impact function through many biophysical mechanisms including alterations to thermodynamic stability and protein dynamics. As these properties of proteins are difficult to investigate, the impacts of core mutations on protein function are poorly understood for most systems. Here, we determined the effects of alanine mutations at all 15 core positions in ubiquitin on function in yeast. The majority (13 of 15) of alanine substitutions supported yeast growth as the sole ubiquitin. The two null mutants (I30A and L43A) were both less stable to temperature-induced unfolding in vitro than wild-type, but were well folded at physiological temperatures. Heteronuclear NMR studies indicated that the L43A mutation reduces temperature stability while retaining a ground-state structure similar to wild-type. This structure enables L43A to bind to common ubiquitin receptors in vitro. Many of the core alanine ubiquitin mutants, including one of the null variants (I30A), exhibited an increased accumulation of high molecular weight species, suggesting that these mutants caused a defect in the processing of ubiquitin-substrate conjugates. In contrast, L43A exhibited a unique accumulation pattern with reduced levels of high molecular weight species and undetectable levels of free ubiquitin. When conjugation to other proteins was blocked, L43A ubiquitin accumulated as free ubiquitin in yeast. Based on these findings we speculate that ubiquitin's stability to unfolding may be required for efficient recycling during proteasome-mediated substrate degradation. PMID:24361330
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The impact of the SSIIa null mutations on grain traits and composition in durum wheat.
Botticella, Ermelinda; Sestili, Francesco; Ferrazzano, Gianluca; Mantovani, Paola; Cammerata, Alessandro; D'Egidio, Maria Grazia; Lafiandra, Domenico
2016-09-01
Starch represents a major nutrient in the human diet providing essentially a source of energy. More recently the modification of its composition has been associated with new functionalities both at the nutritional and technological level. Targeting the major starch biosynthetic enzymes has been shown to be a valuable strategy to manipulate the amylose-amylopectin ratio in reserve starch. In the present work a breeding strategy aiming to produce a set of SSIIa (starch synthases IIa) null durum wheat is described. We have characterized major traits such as seed weight, total starch, amylose, protein and β-glucan content in a set of mutant families derived from the introgression of the SSIIa null trait into Svevo, an elite Italian durum wheat cultivar. A large degree of variability was detected and used to select wheat lines with either improved quality traits or agronomic performances. Semolina of a set of two SSIIa null lines showed new rheological behavior and an increased content of all major dietary fiber components, namely arabinoxylans, β-glucans and resistant starch. Furthermore the investigation of gene expression highlighted important differences in some genes involved in starch and β-glucans biosynthesis.
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Null alleles are ubiquitous at microsatellite loci in the Wedge Clam (Donax trunculus)
Cuesta, Jose Antonio; Drake, Pilar; Macpherson, Enrique; Bernatchez, Louis
2017-01-01
Recent studies have reported an unusually high frequency of nonamplifying alleles at microsatellite loci in bivalves. Null alleles have been associated with heterozygous deficits in many studies. While several studies have tested for its presence using different analytical tools, few have empirically tested for its consequences in estimating population structure and differentiation. We characterised 16 newly developed microsatellite loci and show that null alleles are ubiquitous in the wedge clam, Donax trunculus. We carried out several tests to demonstrate that the large heterozygous deficits observed in the newly characterised loci were most likely due to null alleles. We tested the robustness of microsatellite genotyping for population assignment by showing that well-recognised biogeographic regions of the south Atlantic and south Mediterranean coast of Spain harbour genetically different populations. PMID:28439464
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sirt1-null mice develop an autoimmune-like condition
DOE Office of Scientific and Technical Information (OSTI.GOV)
Sequeira, Jedon; Boily, Gino; Bazinet, Stephanie
2008-10-01
The sirt1 gene encodes a protein deacetylase with a broad spectrum of reported substrates. Mice carrying null alleles for sirt1 are viable on outbred genetic backgrounds so we have examined them in detail to identify the biological processes that are dependent on SIRT1. Sera from adult sirt1-null mice contain antibodies that react with nuclear antigens and immune complexes become deposited in the livers and kidneys of these animals. Some of the sirt1-null animals develop a disease resembling diabetes insipidus when they approach 2 years of age although the relationship to the autoimmunity remains unclear. We interpret these observations as consistentmore » with a role for SIRT1 in sustaining normal immune function and in this way delaying the onset of autoimmune disease.« less
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Yao, Yining; Yang, Qinrui; Shao, Chengchen; Liu, Baonian; Zhou, Yuxiang; Xu, Hongmei; Zhou, Yueqin; Tang, Qiqun; Xie, Jianhui
2018-01-01
Rare variants are widely observed in human genome and sequence variations at primer binding sites might impair the process of PCR amplification resulting in dropouts of alleles, named as null alleles. In this study, 5 cases from routine paternity testing using PowerPlex ® 21 System for STR genotyping were considered to harbor null alleles at TH01, FGA, D5S818, D8S1179, and D16S539, respectively. The dropout of alleles was confirmed by using alternative commercial kits AGCU Expressmarker 22 PCR amplification kit and AmpFℓSTR ® . Identifiler ® Plus Kit, and sequencing results revealed a single base variation at the primer binding site of each STR locus. Results from the collection of previous reports show that null alleles at D5S818 were frequently observed in population detected by two PowerPlex ® typing systems and null alleles at D19S433 were mostly observed in Japanese population detected by two AmpFℓSTR™ typing systems. Furthermore, the most popular mutation type appeared the transition from C to T with G to A, which might have a potential relationship with DNA methylation. Altogether, these results can provide helpful information in forensic practice to the elimination of genotyping discrepancy and the development of primer sets. Copyright © 2017 Elsevier B.V. All rights reserved.
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Beatty, William S.; Webb, Elisabeth B.; Kesler, Dylan C.; Naylor, Luke W.; Raedeke, Andrew H.; Humburg, Dale D.; Coluccy, John M.; Soulliere, G.
2015-01-01
Bird conservation Joint Ventures are collaborative partnerships between public agencies and private organizations that facilitate habitat management to support waterfowl and other bird populations. A subset of Joint Ventures has developed energetic carrying capacity models (ECCs) to translate regional waterfowl population goals into habitat objectives during the non-breeding period. Energetic carrying capacity models consider food biomass, metabolism, and available habitat to estimate waterfowl carrying capacity within an area. To evaluate Joint Venture ECCs in the context of waterfowl space use, we monitored 33 female mallards (Anas platyrhynchos) and 55 female American black ducks (A. rubripes) using global positioning system satellite telemetry in the central and eastern United States. To quantify space use, we measured first-passage time (FPT: time required for an individual to transit across a circle of a given radius) at biologically relevant spatial scales for mallards (3.46 km) and American black ducks (2.30 km) during the non-breeding period, which included autumn migration, winter, and spring migration. We developed a series of models to predict FPT using Joint Venture ECCs and compared them to a biological null model that quantified habitat composition and a statistical null model, which included intercept and random terms. Energetic carrying capacity models predicted mallard space use more efficiently during autumn and spring migrations, but the statistical null was the top model for winter. For American black ducks, ECCs did not improve predictions of space use; the biological null was top ranked for winter and the statistical null was top ranked for spring migration. Thus, ECCs provided limited insight into predicting waterfowl space use during the non-breeding season. Refined estimates of spatial and temporal variation in food abundance, habitat conditions, and anthropogenic disturbance will likely improve ECCs and benefit conservation planners in linking non-breeding waterfowl habitat objectives with distribution and population parameters. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
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Cytokine profiles in interstitial fluid from chronic atopic dermatitis skin.
Szegedi, K; Lutter, R; Res, P C; Bos, J D; Luiten, R M; Kezic, S; Middelkamp-Hup, M A
2015-11-01
The in vivo levels of inflammatory mediators in chronic atopic dermatitis (AD) skin are not well-defined due to the lack of a non-invasive or minimally invasive sampling technique. To investigate the cytokine milieu in interstitial fluid (ISF) collected from chronic lesional AD skin as compared to ISF from non-lesional AD skin and/or healthy donor skin. ISF was obtained using a minimally invasive technique of creating micropores in the skin by a laser, and harvesting ISF through aspiration. We determined the levels of 33 cytokines by Luminex and ELISA in ISF and plasma from sixteen AD patients and twelve healthy individuals. In seven AD patients, we analysed the IL-13, IL-31, IL-17, IL-22 and IFN-γ production by T cells isolated from lesional skin. AD patients were genotyped for the filaggrin gene (FLG)-null mutations 2282del4, R501X, R2447X and S3247X. Twenty-five of 33 examined mediators were detected in the ISF. The levels of IL-1α, IL-1β, IL-18, IL-1RA, IL-5, IL-13, IL-6, IL-8, TNF-α, RANTES(CCL-5), MIG(CXCL-9), IP-10(CXCL-10), TARC(CCL-17), VEGF and G-CSF showed significant differences between either lesional, non-lesional and/or healthy skin. IP-10 levels in ISF from lesional and non-lesional AD skin showed significant correlation with IP-10 blood levels. IP-10 also showed a significant correlation with clinical severity (SCORAD), as did IL-13. Levels of both IP-10 and IL-13 were more pronounced in patients with FLG-null mutations. Furthermore, FLG-null mutation carriers had more severe AD. The presented minimally invasive technique is a valuable tool to determine the in vivo cytokine profile of AD skin. © 2015 European Academy of Dermatology and Venereology.
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Trio’s Rho-specific GEF domain is the missing Gαq effector in C. elegans
Williams, Stacey L.; Lutz, Susanne; Charlie, Nicole K.; Vettel, Christiane; Ailion, Michael; Coco, Cassandra; Tesmer, John J.G.; Jorgensen, Erik M.; Wieland, Thomas; Miller, Kenneth G.
2007-01-01
The Gαq pathway is essential for animal life and is a central pathway for driving locomotion, egg laying, and growth in Caenorhabditis elegans, where it exerts its effects through EGL-8 (phospholipase Cβ [PLCβ]) and at least one other effector. To find the missing effector, we performed forward genetic screens to suppress the slow growth and hyperactive behaviors of mutants with an overactive Gαq pathway. Four suppressor mutations disrupted the Rho-specific guanine-nucleotide exchange factor (GEF) domain of UNC-73 (Trio). The mutations produce defects in neuronal function, but not neuronal development, that cause sluggish locomotion similar to animals lacking EGL-8 (PLCβ). Strains containing null mutations in both EGL-8 (PLCβ) and UNC-73 (Trio RhoGEF) have strong synthetic phenotypes that phenocopy the arrested growth and near-complete paralysis of Gαq-null mutants. Using cell-based and biochemical assays, we show that activated C. elegans Gαq synergizes with Trio RhoGEF to activate RhoA. Activated Gαq and Trio RhoGEF appear to be part of a signaling complex, because they coimmunoprecipitate when expressed together in cells. Our results show that Trio’s Rho-specific GEF domain is a major Gαq effector that, together with PLCβ, mediates the Gαq signaling that drives the locomotion, egg laying, and growth of the animal. PMID:17942708
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Takayanagi-Kiya, Seika; Jin, Yishi
2016-07-07
The highly conserved cochaperone DnaJ/Hsp40 family proteins are known to interact with molecular chaperone Hsp70, and can regulate many cellular processes including protein folding, translocation, and degradation. In studies of Caenorhabditis elegans locomotion mutants, we identified a gain-of-function (gf) mutation in dnj-17 closely linked to the widely used e156 null allele of C. elegans GAD (glutamic acid decarboxylase) unc-25 dnj-17 encodes a DnaJ protein orthologous to human DNAJA5. In C. elegans DNJ-17 is a cytosolic protein and is broadly expressed in many tissues. dnj-17(gf) causes a single amino acid substitution in a conserved domain, and behaves as a hypermorphic mutation. The effect of this dnj-17(gf) is most prominent in mutants lacking GABA synaptic transmission. In a seizure model caused by a mutation in the ionotropic acetylcholine receptor acr-2(gf), dnj-17(gf) exacerbates the convulsion phenotype in conjunction with absence of GABA. Null mutants of dnj-17 show mild resistance to aldicarb, while dnj-17(gf) is hypersensitive. These results highlight the importance of DnaJ proteins in regulation of C. elegans locomotor circuit, and provide insights into the in vivo roles of DnaJ proteins in humans. Copyright © 2016 Takayanagi-Kiya and Jin.
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Glycosylation of Cblns attenuates their receptor binding.
Rong, Yongqi; Bansal, Parmil K; Wei, Peng; Guo, Hong; Correia, Kristen; Parris, Jennifer; Morgan, James I
2018-05-18
Cbln1 is the prototype of a family (Cbln1-Cbln4) of secreted glycoproteins and is essential for normal synapse structure and function in cerebellum by bridging presynaptic Nrxn to postsynaptic Grid2. Here we report the effects of glycosylation on the in vitro receptor binding properties of Cblns. Cbln1, 2 and 4 harbor two N-linked glycosylation sites, one at the N-terminus is in a region implicated in Nrxn binding and the second is in the C1q domain, a region involved in Grid2 binding. Mutation (asparagine to glutamine) of the N-terminal site, increased neurexin binding whereas mutation of the C1q site markedly increased Grid2 binding. These mutations did not influence subunit composition of Cbln trimeric complexes (mediated through the C1q domain) nor their assembly into hexamers (mediated by the N-terminal region). Therefore, glycosylation likely masks the receptor binding interfaces of Cblns. As Cbln4 has undetectable Grid2 binding in vitro we assessed whether transgenic expression of wild type Cbln4 or its glycosylation mutants rescued the Cbln1-null phenotype in vivo. Cbln4 partially rescued and both glycosylation mutants completely rescued ataxia in cbln1-null mice. Thus Cbln4 has intrinsic Grid2 binding that is attenuated by glycosylation, and glycosylation mutants exhibit gain of function in vivo. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.
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Starkey, Jason; Mellinger, Erica; Zhang, Dan; Chadha, Pooja; Carmichael, Jillian
2017-01-01
ABSTRACT The initial goal of this study was to reexamine the requirement of UL21 for herpes simplex virus 1 (HSV-1) replication. Previous studies suggested that UL21 is dispensable for replication in cell cultures, but a recent report on HSV-2 challenges those findings. As was done for the HSV-2 study, a UL21-null virus was made and propagated on complementing cells to discourage selection of compensating mutations. This HSV-1 mutant was able to replicate in noncomplementing cells, even at a low multiplicity of infection (MOI), though a reduction in titer was observed. Also, increased proportions of empty capsids were observed in the cytoplasm, suggesting a role for UL21 in preventing their exit from the nucleus. Surprisingly, passage of the null mutant resulted in rapid outgrowth of syncytial (Syn) variants. This was unexpected because UL21 has been shown to be required for the Syn phenotype. However, earlier experiments made use of only the A855V syncytial mutant of glycoprotein B (gB), and the Syn phenotype can also be produced by substitutions in glycoprotein K (gK), UL20, and UL24. Sequencing of the syncytial variants revealed mutations in the gK locus, but UL21 was shown to be dispensable for UL20Syn and UL24Syn. To test whether UL21 is needed only for the A855V mutant, additional gBSyn derivatives were examined in the context of the null virus, and all produced lytic rather than syncytial sites of infection. Thus, UL21 is required only for the gBSyn phenotype. This is the first example of a differential requirement for a viral protein across the four syn loci. IMPORTANCE UL21 is conserved among alphaherpesviruses, but its role is poorly understood. This study shows that HSV-1 can replicate without UL21, although the virus titers are greatly reduced. The null virus had greater proportions of empty (DNA-less) capsids in the cytoplasm of infected cells, suggesting that UL21 may play a role in retaining them in the nucleus. This is consistent with reports showing UL21 to be capsid associated and localized to the nuclei of infected cells. UL21 also appears to be needed for viral membrane activities. It was found to be required for virus-mediated cell fusion, but only for mutants that harbor syncytial mutations in gB (not variants of gK, UL20, or UL24). The machinery needed for syncytial formation is similar to that needed for direct spread of the virus through cell junctions, and these studies show that UL21 is required for cell-to-cell spread even in the absence of syncytial mutations. PMID:28794039
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Zimic, Mirko; Sheen, Patricia; Quiliano, Miguel; Gutierrez, Andrés; Gilman, Robert H.
2010-01-01
Resistance to pyrazinamide in Mycobacterium tuberculosis is usually associated with a reduction of pyrazinamidase activity caused by mutations in pncA, the pyrazinamidase coding gene. Pyrazinamidase is a hydrolase that converts pyrazinamide, the antituberculous drug against the latent stage, to the active compound, pyrazinoic acid. To better understand the relationship between pncA mutations and pyrazinamide-resistance, it is necessary to analyze the distribution of pncA mutations from pyrazinamide resistant strains. We determined the distribution of Peruvian and globally reported pncA missense mutations from M. tuberculosis clinical isolates resistant to pyrazinamide. The distributions of the single amino acid substitutions were compared at the secondary-structure-domains level. The distribution of the Peruvian mutations followed a similar pattern as the mutations reported globally. A consensus clustering of mutations was observed in hot-spot regions located in the metal coordination site and to a lesser extent in the active site of the enzyme. The data was not able to reject the null hypothesis that both distributions are similar, suggesting that pncA mutations associated to pyrazinamide resistance in M. tuberculosis, follow a conserved pattern responsible to impair the pyrazinamidase activity. PMID:19963078
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Futai, Eugene; Osawa, Satoko; Cai, Tetsuo; Fujisawa, Tomoya; Ishiura, Shoichi; Tomita, Taisuke
2016-01-01
γ-Secretase is a multisubunit membrane protein complex containing presenilin (PS1) as a catalytic subunit. Familial Alzheimer disease (FAD) mutations within PS1 were analyzed in yeast cells artificially expressing membrane-bound substrate, amyloid precursor protein, or Notch fused to Gal4 transcriptional activator. The FAD mutations, L166P and G384A (Leu-166 to Pro and Gly-384 to Ala substitution, respectively), were loss-of-function in yeast. We identified five amino acid substitutions that suppress the FAD mutations. The cleavage of amyloid precursor protein or Notch was recovered by the secondary mutations. We also found that secondary mutations alone activated the γ-secretase activity. FAD mutants with suppressor mutations, L432M or S438P within TMD9 together with a missense mutation in the second or sixth loops, regained γ-secretase activity when introduced into presenilin null mouse fibroblasts. Notably, the cells with suppressor mutants produced a decreased amount of Aβ42, which is responsible for Alzheimer disease. These results indicate that the yeast system is useful to screen for mutations and chemicals that modulate γ-secretase activity. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.
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Rett Syndrome Mutation MeCP2 T158A Disrupts DNA Binding, Protein Stability and ERP Responses
Goffin, Darren; Allen, Megan; Zhang, Le; Amorim, Maria; Wang, I-Ting Judy; Reyes, Arith-Ruth S.; Mercado-Berton, Amy; Ong, Caroline; Cohen, Sonia; Hu, Linda; Blendy, Julie A.; Carlson, Gregory C.; Siegel, Steve J.; Greenberg, Michael E.; Zhou, Zhaolan (Joe)
2011-01-01
Mutations in the MECP2 gene cause the autism spectrum disorder Rett Syndrome (RTT). One of the most common mutations associated with RTT occurs at MeCP2 Threonine 158 converting it to Methionine (T158M) or Alanine (T158A). To understand the role of T158 mutation in the pathogenesis of RTT, we generated knockin mice recapitulating MeCP2 T158A mutation. Here we show a causal role for T158A mutation in the development of RTT-like phenotypes including developmental regression, motor dysfunction, and learning and memory deficits. These phenotypes resemble those in Mecp2-null mice and manifest through a reduction in MeCP2 binding to methylated DNA and a decrease in MeCP2 protein stability. Importantly, the age-dependent development of event-related neuronal responses are disrupted by MeCP2 mutation, suggesting that impaired neuronal circuitry underlies the pathogenesis of RTT and that assessment of event-related potentials may serve as a biomarker for RTT and treatment evaluation. PMID:22119903
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Thioredoxin-interacting protein (Txnip) is a critical regulator of hepatic glucose production.
Chutkow, William A; Patwari, Parth; Yoshioka, Jun; Lee, Richard T
2008-01-25
Thioredoxin-interacting protein (Txnip) has been recently described as a possible link between cellular redox state and metabolism; Txnip binds thioredoxin and inhibits its disulfide reductase activity in vitro, while a naturally occurring strain of Txnip-deficient mice has hyperlipidemia, hypoglycemia, and ketosis exacerbated by fasting. We generated Txnip-null mice to investigate the role of Txnip in glucose homeostasis. Txnip-null mice were hypoglycemic, hypoinsulinemic, and had blunted glucose production following a glucagon challenge, consistent with a central liver glucose-handling defect. Glucose release from isolated Txnip-null hepatocytes was 2-fold lower than wild-type hepatocytes, whereas beta-hydroxybutyrate release was increased 2-fold, supporting an intrinsic defect in hepatocyte glucose metabolism. While hepatocyte-specific gene deletion of Txnip did not alter glucose clearance compared with littermate controls, Txnip expression in the liver was required for maintaining normal fasting glycemia and glucose production. In addition, hepatic overexpression of a Txnip transgene in wild-type mice resulted in elevated serum glucose levels and decreased ketone levels. Liver homogenates from Txnip-null mice had no significant differences in the glutathione oxidation state or in the amount of available thioredoxin. However, overexpression of wild-type Txnip in Txnip-null hepatocytes rescued cellular glucose production, whereas overexpression of a C247S mutant Txnip, which does not bind thioredoxin, had no effect. These data demonstrate that Txnip is required for normal glucose homeostasis in the liver. While available thioredoxin is not changed in Txnip-null mice, the effects of Txnip on glucose homeostasis are abolished by a single cysteine mutation that inhibits binding to thioredoxin.
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Inborn Errors of Human JAKs and STATs
Casanova, Jean-Laurent; Holland, Steven M.; Notarangelo, Luigi D.
2012-01-01
Inborn errors of the genes encoding two of the four human JAKs (JAK3 and TYK2) and three of the six human STATs (STAT1, STAT3, and STAT5B) have been described. We review the disorders arising from mutations in these five genes, highlighting the way in which the molecular and cellular pathogenesis of these conditions has been clarified by the discovery of inborn errors of cytokines, hormones, and their receptors, including those interacting with JAKs and STATs. The phenotypic similarities between mice and humans lacking individual JAK-STAT components suggest that the functions of JAKs and STATs are largely conserved in mammals. However, a wide array of phenotypic differences has emerged between mice and humans carrying bi-allelic null alleles of JAK3, TYK2, STAT1, or STAT5B. Moreover, the high level of allelic heterogeneity at the human JAK3, STAT1, and STAT3 loci has revealed highly diverse immunological and clinical phenotypes, which had not been anticipated. PMID:22520845
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Inborn errors of human JAKs and STATs.
Casanova, Jean-Laurent; Holland, Steven M; Notarangelo, Luigi D
2012-04-20
Inborn errors of the genes encoding two of the four human JAKs (JAK3 and TYK2) and three of the six human STATs (STAT1, STAT3, and STAT5B) have been described. We review the disorders arising from mutations in these five genes, highlighting the way in which the molecular and cellular pathogenesis of these conditions has been clarified by the discovery of inborn errors of cytokines, hormones, and their receptors, including those interacting with JAKs and STATs. The phenotypic similarities between mice and humans lacking individual JAK-STAT components suggest that the functions of JAKs and STATs are largely conserved in mammals. However, a wide array of phenotypic differences has emerged between mice and humans carrying biallelic null alleles of JAK3, TYK2, STAT1, or STAT5B. Moreover, the high degree of allelic heterogeneity at the human JAK3, TYK2, STAT1, and STAT3 loci has revealed highly diverse immunological and clinical phenotypes, which had not been anticipated. Copyright © 2012 Elsevier Inc. All rights reserved.
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NASA Astrophysics Data System (ADS)
Kaminski, Naftali; Allard, John D.; Pittet, Jean F.; Zuo, Fengrong; Griffiths, Mark J. D.; Morris, David; Huang, Xiaozhu; Sheppard, Dean; Heller, Renu A.
2000-02-01
The molecular mechanisms of pulmonary fibrosis are poorly understood. We have used oligonucleotide arrays to analyze the gene expression programs that underlie pulmonary fibrosis in response to bleomycin, a drug that causes lung inflammation and fibrosis, in two strains of susceptible mice (129 and C57BL/6). We then compared the gene expression patterns in these mice with 129 mice carrying a null mutation in the epithelial-restricted integrin 6 subunit (6/-), which develop inflammation but are protected from pulmonary fibrosis. Cluster analysis identified two distinct groups of genes involved in the inflammatory and fibrotic responses. Analysis of gene expression at multiple time points after bleomycin administration revealed sequential induction of subsets of genes that characterize each response. The availability of this comprehensive data set should accelerate the development of more effective strategies for intervention at the various stages in the development of fibrotic diseases of the lungs and other organs.
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Electromagnetic dissipation during asymmetric reconnection with a moderate guide field
NASA Astrophysics Data System (ADS)
Genestreti, Kevin; Burch, James; Cassak, Paul; Torbert, Roy; Phan, Tai; Ergun, Robert; Giles, Barbara; Russell, Chris; Wang, Shan; Akhavan-Tafti, Mojtaba; Varsani, Ali
2017-04-01
We calculate the work done on the plasma by the electromagnetic (EM) field, ⃗Jṡ⃗E', and analyze the related electron currents and electric fields, focusing on a single asymmetric guide field electron diffusion region (EDR) event observed by MMS on 8 December 2015. For this event, each of the four MMS spacecraft observed dissipation of EM energy at the in-plane magnetic null point, though large-scale generation/dissipation was observed inconsistently on the magnetospheric side of the boundary. The current at the null was carried by a beam-like population of magnetosheath electrons traveling anti-parallel to the guide field, whereas the current on the Earthward side of the boundary was carried by crescent-shaped electron distributions. We also analyze the terms in Ohm's law, finding a large residual electric field throughout the EDR, inertial and pressure divergence fields at the null, and pressure divergence fields at the magnetosphere-side EDR. Our analysis of the terms in Ohm's law suggests that the EDR had significant three-dimensional structure.
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Heme deficiency in erythroid lineage causes differentiation arrest and cytoplasmic iron overload.
Nakajima, O; Takahashi, S; Harigae, H; Furuyama, K; Hayashi, N; Sassa, S; Yamamoto, M
1999-01-01
Erythroid 5-aminolevulinate synthase (ALAS-E) catalyzes the first step of heme biosynthesis in erythroid cells. Mutation of human ALAS-E causes the disorder X-linked sideroblastic anemia. To examine the roles of heme during hematopoiesis, we disrupted the mouse ALAS-E gene. ALAS-E-null embryos showed no hemoglobinized cells and died by embryonic day 11.5, indicating that ALAS-E is the principal isozyme contributing to erythroid heme biosynthesis. In the ALAS-E-null mutant embryos, erythroid differentiation was arrested, and an abnormal hematopoietic cell fraction emerged that accumulated a large amount of iron diffusely in the cytoplasm. In contrast, we found typical ring sideroblasts that accumulated iron mostly in mitochondria in adult mice chimeric for ALAS-E-null mutant cells, indicating that the mode of iron accumulation caused by the lack of ALAS-E is different in primitive and definitive erythroid cells. These results demonstrate that ALAS-E, and hence heme supply, is necessary for differentiation and iron metabolism of erythroid cells. PMID:10562540
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High-Throughput Genome Editing and Phenotyping Facilitated by High Resolution Melting Curve Analysis
Thomas, Holly R.; Percival, Stefanie M.; Yoder, Bradley K.; Parant, John M.
2014-01-01
With the goal to generate and characterize the phenotypes of null alleles in all genes within an organism and the recent advances in custom nucleases, genome editing limitations have moved from mutation generation to mutation detection. We previously demonstrated that High Resolution Melting (HRM) analysis is a rapid and efficient means of genotyping known zebrafish mutants. Here we establish optimized conditions for HRM based detection of novel mutant alleles. Using these conditions, we demonstrate that HRM is highly efficient at mutation detection across multiple genome editing platforms (ZFNs, TALENs, and CRISPRs); we observed nuclease generated HRM positive targeting in 1 of 6 (16%) open pool derived ZFNs, 14 of 23 (60%) TALENs, and 58 of 77 (75%) CRISPR nucleases. Successful targeting, based on HRM of G0 embryos correlates well with successful germline transmission (46 of 47 nucleases); yet, surprisingly mutations in the somatic tail DNA weakly correlate with mutations in the germline F1 progeny DNA. This suggests that analysis of G0 tail DNA is a good indicator of the efficiency of the nuclease, but not necessarily a good indicator of germline alleles that will be present in the F1s. However, we demonstrate that small amplicon HRM curve profiles of F1 progeny DNA can be used to differentiate between specific mutant alleles, facilitating rare allele identification and isolation; and that HRM is a powerful technique for screening possible off-target mutations that may be generated by the nucleases. Our data suggest that micro-homology based alternative NHEJ repair is primarily utilized in the generation of CRISPR mutant alleles and allows us to predict likelihood of generating a null allele. Lastly, we demonstrate that HRM can be used to quickly distinguish genotype-phenotype correlations within F1 embryos derived from G0 intercrosses. Together these data indicate that custom nucleases, in conjunction with the ease and speed of HRM, will facilitate future high-throughput mutation generation and analysis needed to establish mutants in all genes of an organism. PMID:25503746
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2013-07-01
in addition to mutations on COL1A1 and COL5A2. These mutations result in amino acid substitutions, RNA splicing alterations, deletions, or null...Romanic and colleagues demonstrate that COL1A1 is larger, shorter, and apparently stiffer; whereas in the presence of PIIINP/ COL1A1
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Two novel mutations in the Norrie disease gene associated with the classical ocular phenotype.
Caballero, M; Veske, A; Rodriguez, J J; Lugo, N; Schroeder, B; Hesse, L; Gal, A
1996-12-01
Norrie disease (ND) is a rare X-linked recessive disorder characterized by congenital blindness due to a degenerative and proliferative dysplasia of the neuroretina and, occasionally, by deafness and mental handicap. Here, we report two novel mutations detected in patients with the classical eye features of ND. Both the one-base pair insertion in exon II (544/545 insA) and the two-base pair deletion in the start codon (418delTG) of the ND gene predict a functional 'null allele', i.e. the complete absence of the corresponding gene product.
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Grabbe, Roman; Schmitz, Ruth A
2003-04-01
In Klebsiella pneumoniae, the flavoprotein, NifL regulates NifA mediated transcriptional activation of the N2-fixation (nif) genes in response to molecular O2 and ammonium. We investigated the influence of membrane-bound oxidoreductases on nif-regulation by biochemical analysis of purified NifL and by monitoring NifA-mediated expression of nifH'-'lacZ reporter fusions in different mutant backgrounds. NifL-bound FAD-cofactor was reduced by NADH only in the presence of a redox-mediator or inside-out vesicles derived from anaerobically grown K. pneumoniae cells, indicating that in vivo NifL is reduced by electrons derived from membrane-bound oxidoreductases of the anaerobic respiratory chain. This mechanism is further supported by three lines of evidence: First, K. pneumoniae strains carrying null mutations of fdnG or nuoCD showed significantly reduced nif-induction under derepressing conditions, indicating that NifL inhibition of NifA was not relieved in the absence of formate dehydrogenase-N or NADH:ubiquinone oxidoreductase. The same effect was observed in a heterologous Escherichia coli system carrying a ndh null allele (coding for NADH dehydrogenaseII). Second, studying nif-induction in K. pneumoniae revealed that during anaerobic growth in glycerol, under nitrogen-limitation, the presence of the terminal electron acceptor nitrate resulted in a significant decrease of nif-induction. The final line of evidence is that reduced quinone derivatives, dimethylnaphthoquinol and menadiol, are able to transfer electrons to the FAD-moiety of purified NifL. On the basis of these data, we postulate that under anaerobic and nitrogen-limited conditions, NifL inhibition of NifA activity is relieved by reduction of the FAD-cofactor by electrons derived from the reduced quinone pool, generated by anaerobic respiration, that favours membrane association of NifL. We further hypothesize that the quinol/quinone ratio is important for providing the signal to NifL.
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USDA-ARS?s Scientific Manuscript database
To determine if membrane-bound G-proteins are involved in the regulation of defense responses against ozone in the leaf apoplast, the apoplastic concentrations of ascorbic acid and phenolic glycosides in Arabidopsis thaliana L. lines with null mutations in the alpha- and beta-subunits were compared ...
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USDA-ARS?s Scientific Manuscript database
Decrease of cellular zinc in the epithelium of the prostate has been implicated in the development of prostate cancer. To investigate whether ZnT7, a zinc transporter involved in intracellular zinc accumulation, plays a role in prostate cancer development, we have generated and characterized a trans...
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Kroken, Abby R; Chen, Camille K; Evans, David J; Yahr, Timothy L; Fleiszig, Suzanne M J
2018-05-01
Pseudomonas aeruginosa is internalized into multiple types of epithelial cell in vitro and in vivo and yet is often regarded as an exclusively extracellular pathogen. Paradoxically, ExoS, a type three secretion system (T3SS) effector, has antiphagocytic activities but is required for intracellular survival of P. aeruginosa and its occupation of bleb niches in epithelial cells. Here, we addressed mechanisms for this dichotomy using invasive (ExoS-expressing) P. aeruginosa and corresponding effector-null isogenic T3SS mutants, effector-null mutants of cytotoxic P. aeruginosa with and without ExoS transformation, antibiotic exclusion assays, and imaging using a T3SS-GFP reporter. Except for effector-null PA103, all strains were internalized while encoding ExoS. Intracellular bacteria showed T3SS activation that continued in replicating daughter cells. Correcting the fleQ mutation in effector-null PA103 promoted internalization by >10-fold with or without ExoS. Conversely, mutating fleQ in PAO1 reduced internalization by >10-fold, also with or without ExoS. Effector-null PA103 remained less well internalized than PAO1 matched for fleQ status, but only with ExoS expression, suggesting additional differences between these strains. Quantifying T3SS activation using GFP fluorescence and quantitative reverse transcription-PCR (qRT-PCR) showed that T3SS expression was hyperinducible for strain PA103Δ exoUT versus other isolates and was unrelated to fleQ status. These findings support the principle that P. aeruginosa is not exclusively an extracellular pathogen, with internalization influenced by the relative proportions of T3SS-positive and T3SS-negative bacteria in the population during host cell interaction. These data also challenge current thinking about T3SS effector delivery into host cells and suggest that T3SS bistability is an important consideration in studying P. aeruginosa pathogenesis. IMPORTANCE P. aeruginosa is often referred to as an extracellular pathogen, despite its demonstrated capacity to invade and survive within host cells. Fueling the confusion, P. aeruginosa encodes T3SS effectors with anti-internalization activity that, paradoxically, play critical roles in intracellular survival. Here, we sought to address why ExoS does not prevent internalization of the P. aeruginosa strains that natively encode it. Results showed that ExoS exerted unusually strong anti-internalization activity under conditions of expression in the effector-null background of strain PA103, often used to study T3SS effector activity. Inhibition of internalization was associated with T3SS hyperinducibility and ExoS delivery. PA103 fleQ mutation, preventing flagellar assembly, further reduced internalization but did so independently of ExoS. The results revealed intracellular T3SS expression by all strains and suggested that T3SS bistability influences P. aeruginosa internalization. These findings reconcile controversies in the literature surrounding P. aeruginosa internalization and support the principle that P. aeruginosa is not exclusively an extracellular pathogen. Copyright © 2018 Kroken et al.
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RAX and anophthalmia in humans: Evidence of brain anomalies
Youssef, Mohamed A.; Bayoumi, Nader; ElShakankiri, Nihal; Marzouk, Iman; Hauser, Philippe; Schorderet, Daniel F.
2012-01-01
Purpose To report the clinical and genetic study of two families of Egyptian origin with clinical anophthalmia. To further determine the role of the retina and anterior neural fold homeobox gene (RAX) in anophthalmia and associated cerebral malformations. Methods Three patients with clinical anophthalmia and first-degree relatives from two consanguineous families of Egyptian origin underwent full ophthalmologic, general and neurologic examination, and blood tests. Cerebral magnetic resonance imaging (MRI) was performed in the index cases of both families. Genomic DNA was prepared from venous leukocytes, and direct sequencing of all the exons and intron-exon junctions of RAX was performed after PCR amplification. Results Clinical bilateral anophthalmia was observed in all three patients. General and neurologic examinations were normal; obesity and delay in psychomotor development were observed in the isolated case. Orbital MRI showed a hypoplastic orbit with present but rudimentary extraocular muscles and normal lacrimal glands. Cerebral MRI showed agenesis of the optic nerves, optic tracts, and optic chiasma. In the index case of family A, the absence of the frontal and sphenoidal sinuses was also noted. In the index case of family B, only the sphenoidal sinus was absent, and there was significant cortical atrophy. The three patients carried a novel homozygous c.543+3A>G mutation (IVS2+3A>G) in RAX. Parents were healthy heterozygous carriers. No mutations were detected in orthodenticle homeobox 2 (OTX2), ventral anterior homeobox 1 (VAX1), or sex determining region Y-box 2 (SOX2). Conclusions This is the first report of a homozygous splicing RAX mutation associated with autosomal recessive bilateral anophthalmia. To our knowledge, only two isolated cases of anophthalmia, three null and one missense case affecting nuclear localization or the DNA-binding homeodomain, have been found to be caused by compound heterozygote RAX mutations. A novel missense RAX mutation was identified in three patients with bilateral anophthalmia and a distinct systemic and neurologic phenotype. The mutation potentially affects splicing of the last exon and is thought to result in a protein that has an aberrant homeodomain and no paired-tail domain. Functional consequences of this change still need to be characterized. PMID:22736936
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RAX and anophthalmia in humans: evidence of brain anomalies.
Abouzeid, Hana; Youssef, Mohamed A; Bayoumi, Nader; ElShakankiri, Nihal; Marzouk, Iman; Hauser, Philippe; Schorderet, Daniel F
2012-01-01
To report the clinical and genetic study of two families of Egyptian origin with clinical anophthalmia. To further determine the role of the retina and anterior neural fold homeobox gene (RAX) in anophthalmia and associated cerebral malformations. Three patients with clinical anophthalmia and first-degree relatives from two consanguineous families of Egyptian origin underwent full ophthalmologic, general and neurologic examination, and blood tests. Cerebral magnetic resonance imaging (MRI) was performed in the index cases of both families. Genomic DNA was prepared from venous leukocytes, and direct sequencing of all the exons and intron-exon junctions of RAX was performed after PCR amplification. Clinical bilateral anophthalmia was observed in all three patients. General and neurologic examinations were normal; obesity and delay in psychomotor development were observed in the isolated case. Orbital MRI showed a hypoplastic orbit with present but rudimentary extraocular muscles and normal lacrimal glands. Cerebral MRI showed agenesis of the optic nerves, optic tracts, and optic chiasma. In the index case of family A, the absence of the frontal and sphenoidal sinuses was also noted. In the index case of family B, only the sphenoidal sinus was absent, and there was significant cortical atrophy. The three patients carried a novel homozygous c.543+3A>G mutation (IVS2+3A>G) in RAX. Parents were healthy heterozygous carriers. No mutations were detected in orthodenticle homeobox 2 (OTX2), ventral anterior homeobox 1 (VAX1), or sex determining region Y-box 2 (SOX2). This is the first report of a homozygous splicing RAX mutation associated with autosomal recessive bilateral anophthalmia. To our knowledge, only two isolated cases of anophthalmia, three null and one missense case affecting nuclear localization or the DNA-binding homeodomain, have been found to be caused by compound heterozygote RAX mutations. A novel missense RAX mutation was identified in three patients with bilateral anophthalmia and a distinct systemic and neurologic phenotype. The mutation potentially affects splicing of the last exon and is thought to result in a protein that has an aberrant homeodomain and no paired-tail domain. Functional consequences of this change still need to be characterized.
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Mutations in SLC39A14 disrupt manganese homeostasis and cause childhood-onset parkinsonism-dystonia.
Tuschl, Karin; Meyer, Esther; Valdivia, Leonardo E; Zhao, Ningning; Dadswell, Chris; Abdul-Sada, Alaa; Hung, Christina Y; Simpson, Michael A; Chong, W K; Jacques, Thomas S; Woltjer, Randy L; Eaton, Simon; Gregory, Allison; Sanford, Lynn; Kara, Eleanna; Houlden, Henry; Cuno, Stephan M; Prokisch, Holger; Valletta, Lorella; Tiranti, Valeria; Younis, Rasha; Maher, Eamonn R; Spencer, John; Straatman-Iwanowska, Ania; Gissen, Paul; Selim, Laila A M; Pintos-Morell, Guillem; Coroleu-Lletget, Wifredo; Mohammad, Shekeeb S; Yoganathan, Sangeetha; Dale, Russell C; Thomas, Maya; Rihel, Jason; Bodamer, Olaf A; Enns, Caroline A; Hayflick, Susan J; Clayton, Peter T; Mills, Philippa B; Kurian, Manju A; Wilson, Stephen W
2016-05-27
Although manganese is an essential trace metal, little is known about its transport and homeostatic regulation. Here we have identified a cohort of patients with a novel autosomal recessive manganese transporter defect caused by mutations in SLC39A14. Excessive accumulation of manganese in these patients results in rapidly progressive childhood-onset parkinsonism-dystonia with distinctive brain magnetic resonance imaging appearances and neurodegenerative features on post-mortem examination. We show that mutations in SLC39A14 impair manganese transport in vitro and lead to manganese dyshomeostasis and altered locomotor activity in zebrafish with CRISPR-induced slc39a14 null mutations. Chelation with disodium calcium edetate lowers blood manganese levels in patients and can lead to striking clinical improvement. Our results demonstrate that SLC39A14 functions as a pivotal manganese transporter in vertebrates.
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Mutations in SLC39A14 disrupt manganese homeostasis and cause childhood-onset parkinsonism–dystonia
Tuschl, Karin; Meyer, Esther; Valdivia, Leonardo E.; Zhao, Ningning; Dadswell, Chris; Abdul-Sada, Alaa; Hung, Christina Y.; Simpson, Michael A.; Chong, W. K.; Jacques, Thomas S.; Woltjer, Randy L.; Eaton, Simon; Gregory, Allison; Sanford, Lynn; Kara, Eleanna; Houlden, Henry; Cuno, Stephan M.; Prokisch, Holger; Valletta, Lorella; Tiranti, Valeria; Younis, Rasha; Maher, Eamonn R.; Spencer, John; Straatman-Iwanowska, Ania; Gissen, Paul; Selim, Laila A. M.; Pintos-Morell, Guillem; Coroleu-Lletget, Wifredo; Mohammad, Shekeeb S.; Yoganathan, Sangeetha; Dale, Russell C.; Thomas, Maya; Rihel, Jason; Bodamer, Olaf A.; Enns, Caroline A.; Hayflick, Susan J.; Clayton, Peter T.; Mills, Philippa B.; Kurian, Manju A.; Wilson, Stephen W.
2016-01-01
Although manganese is an essential trace metal, little is known about its transport and homeostatic regulation. Here we have identified a cohort of patients with a novel autosomal recessive manganese transporter defect caused by mutations in SLC39A14. Excessive accumulation of manganese in these patients results in rapidly progressive childhood-onset parkinsonism–dystonia with distinctive brain magnetic resonance imaging appearances and neurodegenerative features on post-mortem examination. We show that mutations in SLC39A14 impair manganese transport in vitro and lead to manganese dyshomeostasis and altered locomotor activity in zebrafish with CRISPR-induced slc39a14 null mutations. Chelation with disodium calcium edetate lowers blood manganese levels in patients and can lead to striking clinical improvement. Our results demonstrate that SLC39A14 functions as a pivotal manganese transporter in vertebrates. PMID:27231142
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Cybulski, C; Górski, B; Huzarski, T; Byrski, T; Gronwald, J; Debniak, T; Wokolorczyk, D; Jakubowska, A; Serrano-Fernández, P; Dork, T; Narod, S A; Lubinski, J
2009-02-01
Carriers of heterozygous mutations in CHEK2 or BRCA1 are at increased risk of breast cancer. These mutations are rare and a very small number of women in a population will carry two mutations. However, it is of interest to estimate the breast cancer risks associated with carrying two mutations because this information may be informative for genetic counsellors and may provide clues to the carcinogenic process. We genotyped 7782 Polish breast cancer patients and 6233 controls for seven founder mutations in BRCA1 and CHEK2. Odds ratios (OR) and 95% confidence intervals (CI) were estimated for the mutations, singly and in combination. Of the 7782 women with breast cancer, 1091 had one mutation (14.0%) and 37 had two mutations (0.5%). Compared to controls, the odds ratio for a BRCA1 mutation in isolation was 13.1 (95% CI 8.2 to 21). The odds ratio was smaller for BRCA1 mutation carriers who also carried a CHEK2 mutation (OR 6.6, 95% CI 1.5 to 29), but the difference was not statistically significant. In contrast, the odds ratio for women who carried two CHEK2 mutations (OR 3.9, 95% CI 1.5 to 10) was greater than that for women who carried one CHEK2 mutation (OR 1.9, 95% CI 1.6 to 2.1). The odds ratio for women who carried both a truncating mutation and the missense mutation in CHEK2 was 7.0 (95% CI 0.9 to 56) and was greater than for women who carried the truncating mutation alone (OR 3.3, 95% CI 2.4 to 4.3) or the missense mutation alone (OR 1.6, 95% CI 1.4 to 1.9), but the difference was not statistically significant. Our study suggests that the risk of breast cancer in carriers of a deleterious CHEK2 mutation is increased if the second allele is the I157T missense variant. However, the presence of a CHEK2 mutation in women with a BRCA1 mutation may not increase their risk beyond that of the BRCA1 mutation alone. These suggestive findings need to be verified in other studies.
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Luzzi, Simona; Colleoni, Lara; Corbetta, Paola; Baldinelli, Sara; Fiori, Chiara; Girelli, Francesca; Silvestrini, Mauro; Caroppo, Paola; Giaccone, Giorgio; Tagliavini, Fabrizio; Rossi, Giacomina
2017-06-01
Gene coding for progranulin, GRN, is a major gene linked to frontotemporal lobar degeneration. While most of pathogenic GRN mutations are null mutations leading to haploinsufficiency, GRN missense mutations do not have an obvious pathogenicity, and only a few have been revealed to act through different pathogenetic mechanisms, such as cytoplasmic missorting, protein degradation, and abnormal cleavage by elastase. The aim of this study was to disclose the pathogenetic mechanisms of the GRN A199V missense mutation, which was previously reported not to alter physiological progranulin features but was associated with a reduced plasma progranulin level. After investigating the family pedigree, we performed genetic and biochemical analysis on its members and performed RNA expression studies. We found that the mutation segregates with the disease and discovered that its pathogenic feature is the alteration of GRN mRNA splicing, actually leading to haploinsufficiency. Thus, when facing with a missense GRN mutation, its pathogenetic effects should be investigated, especially if associated with low plasma progranulin levels, to determine its nature of either benign polymorphism or pathogenic mutation. Copyright © 2017 Elsevier Inc. All rights reserved.
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Deleterious CHEK2 1100delC and L303X mutants identified among 38 human breast cancer cell lines.
Wasielewski, Marijke; Hanifi-Moghaddam, Pejman; Hollestelle, Antoinette; Merajver, Sofia D; van den Ouweland, Ans; Klijn, Jan G M; Ethier, Stephen P; Schutte, Mieke
2009-01-01
The CHEK2 protein plays a major role in the regulation of DNA damage response pathways. Mutations in the CHEK2 gene, in particular 1100delC, have been associated with increased cancer risks, but the precise function of CHEK2 mutations in carcinogenesis is not known. Human cancer cell lines with CHEK2 mutations are therefore of main interest. Here, we have sequenced 38 breast cancer cell lines for mutations in the CHEK2 gene and identified two cell lines with deleterious CHEK2 mutations. Cell line UACC812 has a nonsense truncating mutation in the CHEK2 kinase domain (L303X) and cell line SUM102PT has the well-known oncogenic CHEK2 1100delC founder mutation. Immunohistochemical analysis revealed that the two CHEK2 mutant cell lines expressed neither CHEK2 nor P-Thr(68) CHEK2 proteins, implying abrogation of normal CHEK2 DNA repair functions. Cell lines UACC812 and SUM102PT thus are the first human CHEK2 null cell lines reported and should therefore be a major help in further unraveling the function of CHEK2 mutations in carcinogenesis.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Tassabehji, M.; Strachan, T.; Colley, A.
Type 1 neurofibromatosis (NF1), Watson syndrome (WS), and Noonan syndrome (NS) show some overlap in clinical manifestations. In addition, WS has been shown to be linked to markers flanking the NF1 locus and a deletion at the NF1 locus demonstrated in a WS patient. This suggests either that WS and NF1 are allelic or the phenotypes arise from mutations in very closely linked genes. Here the authors provide evidence for the former by demonstrating a mutation in the NF1 gene in a family with features of both WS and NS. The mutation is an almost perfect in-frame tandem duplication ofmore » 42 bases in exon 28 of the NF1 gene. Unlike the mutations previously described in classical NF1, which show a preponderance of null alleles, the mutation in this family would be expected to result in a mutant neurofibromin product. 31 refs., 2 figs.« less
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Molecular defects leading to human complement component C6 deficiency in an African-American family
Zhu, Z-B; Totemchokchyakarn, K; Atkinson, T P; Volanakis, J E
1998-01-01
Complement component C6 deficiency (C6D) was diagnosed in a 16-year-old African-American male with meningococcal meningitis. The patient's father and two brothers also had C6D, but gave no history of meningitis or other neisserial infection. By using exon-specific polymerase chain reaction (PCR)/single-strand conformation polymorphism as a screening step and nucleotide sequencing of target exons, we determined that the proband was a compound heterozygote for two C6 gene mutations. The first, 1195delC located in exon 7, is a novel mutation, while the second, 1936delG in exon 12, has been described before to cause C6D in an unrelated African-American individual. Both mutations result in premature termination codons and C6 null alleles. Allele-specific PCR indicated that the proband's two brothers also inherited the 1195delC mutation from their heterozygous mother and the 1936delG mutation from their homozygous father. PMID:9472666
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Bolegenova, N K; Bekmanov, B O; Djansugurova, L B; Bersimbaev, R I; Salama, S A; Au, W W
2009-11-01
We have reported previously that a population near the Semipalatinsk nuclear explosion test site had significantly increased minisatellite mutations (MM), suggesting increased germ-line mutation rates from the exposure in 3 generations. We hypothesize that the MM can be used as a surrogate biomarker for functional genetic alterations, e.g. gene mutations and chromosome aberrations. Therefore, we have investigated the influence of polymorphisms in genes on the expression of MM in the same two populations (247 and 172 individuals, for exposed and control, respectively, in 3 generations), and their relationships with radiation exposure. We have chosen the analyses of three polymorphic DNA - repair genes (XRCC1, XRCC1 and XRCC3) and two xenobiotic detoxification genes (GSTT1 and GSTM1). Among the exposed and in comparison with the wild-type gene, the functionally active XRCC1 Arg194Trp was significantly associated with low MM and over-represented in the exposed compared with the control populations. In a similar analysis, the functionally deficient XRCC1 Arg399Glu and XRCC3 Trp241Met were associated with increased and significantly reduced MM, respectively, but these variant genes were under-represented in the exposed population. Both GSTT1 and GSTM1 nulls were significantly associated with increased MM. The former was under-represented but the latter was significantly over-represented in the exposed compared with the control populations. In summary, the data indicate that the expected enzymatic functions of the polymorphic genes are consistent with the MM expression, except the XRCC1 Arg399Glu variant gene. In addition, the variant genes were retained in the three generations in association with their useful function, except for the GSTM1 null. However, the MM frequencies in the exposed were not consistently and significantly higher than those in the control populations, radiation exposure may therefore not have been the only cause for the high MM frequency among the exposed individuals. Since we studied three generations of citizens, the over- and under-representations of variant genes in the exposed population indicate their persistence and elimination, respectively, from the exposed individuals, suggesting their functional influence on survivability. The latter observation also indicates the complexity of gene and environmental interactions, e.g. the GSTM1 null was significantly over-represented in the exposed population.
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NASA Technical Reports Server (NTRS)
Guan, Changhui; Rosen, Elizabeth S.; Boonsirichai, Kanokporn; Poff, Kenneth L.; Masson, Patrick H.
2003-01-01
The arl2 mutants of Arabidopsis display altered root and hypocotyl gravitropism, whereas their inflorescence stems are fully gravitropic. Interestingly, mutant roots respond like the wild type to phytohormones and an inhibitor of polar auxin transport. Also, their cap columella cells accumulate starch similarly to wild-type cells, and mutant hypocotyls display strong phototropic responses to lateral light stimulation. The ARL2 gene encodes a DnaJ-like protein similar to ARG1, another protein previously implicated in gravity signal transduction in Arabidopsis seedlings. ARL2 is expressed at low levels in all organs of seedlings and plants. arl2-1 arg1-2 double mutant roots display kinetics of gravitropism similar to those of single mutants. However, double mutants carrying both arl2-1 and pgm-1 (a mutation in the starch-biosynthetic gene PHOSPHOGLUCOMUTASE) at the homozygous state display a more pronounced root gravitropic defect than the single mutants. On the other hand, seedlings with a null mutation in ARL1, a paralog of ARG1 and ARL2, behave similarly to the wild type in gravitropism and other related assays. Taken together, the results suggest that ARG1 and ARL2 function in the same gravity signal transduction pathway in the hypocotyl and root of Arabidopsis seedlings, distinct from the pathway involving PGM.
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Cideciyan, Artur V.; Zhao, Xinyu; Nielsen, Lori; Khani, Shahrokh C.; Jacobson, Samuel G.; Palczewski, Krzysztof
1998-01-01
Rhodopsin kinase (RK), a specialized G-protein-coupled receptor kinase expressed in retina, is involved in quenching of light-induced signal transduction in photoreceptors. The role of RK in recovery after photoactivation has been explored in vitro and in vivo experimentally but has not been specifically defined in humans. We investigated the effects on human vision of a mutation in the RK gene causing Oguchi disease, a recessively inherited retinopathy. In vitro experiments demonstrated that the mutation, a deletion of exon 5, abolishes the enzymatic activity of RK and is likely a null. Both a homozygote and heterozygote with this RK mutation had recovery phase abnormalities of rod-isolated photoresponses by electroretinography (ERG); photoactivation was normal. Kinetics of rod bleaching adaptation by psychophysics were dramatically slowed in the homozygote but normal final thresholds were attained. Light adaptation was normal at low backgrounds but became abnormal at higher backgrounds. A slight slowing of cone deactivation kinetics in the homozygote was detected by ERG. Cone bleaching adaptation and background adaptation were normal. In this human in vivo condition without a functional RK and probable lack of phosphorylation and arrestin binding to activated rhodopsin, reduction of photolyzed chromophore and regeneration processes with 11-cis-retinal probably constitute the sole pathway for recovery of rod sensitivity. The role of RK in rods would thus be to accelerate inactivation of activated rhodopsin molecules that in concert with regeneration leads to the normal rate of recovery of sensitivity. Cones may rely mainly on regeneration for the inactivation of photolyzed visual pigment, but RK also contributes to cone recovery. PMID:9419375
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Yang, Jie; Wang, Shih-Kai; Choi, Murim; Reid, Bryan M; Hu, Yuanyuan; Lee, Yuan-Ling; Herzog, Curtis R; Kim-Berman, Hera; Lee, Moses; Benke, Paul J; Kent Lloyd, K C; Simmer, James P; Hu, Jan C-C
2015-01-01
WNT10A is a signaling molecule involved in tooth development, and WNT10A defects are associated with tooth agenesis. We characterized Wnt10a null mice generated by the knockout mouse project (KOMP) and six families with WNT10A mutations, including a novel p.Arg104Cys defect, in the absence of EDA,EDAR, or EDARADD variations. Wnt10a null mice exhibited supernumerary mandibular fourth molars, and smaller molars with abnormal cusp patterning and root taurodontism. Wnt10a−/− incisors showed distinctive apical–lingual wedge-shaped defects. These findings spurred us to closely examine the dental phenotypes of our WNT10A families. WNT10A heterozygotes exhibited molar root taurodontism and mild tooth agenesis (with incomplete penetrance) in their permanent dentitions. Individuals with two defective WNT10A alleles showed severe tooth agenesis and had fewer cusps on their molars. The misshapened molar crowns and roots were consistent with the Wnt10a null phenotype and were not previously associated with WNT10A defects. The missing teeth contrasted with the presence of supplemental teeth in the Wnt10a null mice and demonstrated mammalian species differences in the roles of Wnt signaling in early tooth development. We conclude that molar crown and root dysmorphologies are caused by WNT10A defects and that the severity of the tooth agenesis correlates with the number of defective WNT10A alleles. PMID:25629078
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Predominance of null mutations in ataxia-telangiectasia.
Gilad, S; Khosravi, R; Shkedy, D; Uziel, T; Ziv, Y; Savitsky, K; Rotman, G; Smith, S; Chessa, L; Jorgensen, T J; Harnik, R; Frydman, M; Sanal, O; Portnoi, S; Goldwicz, Z; Jaspers, N G; Gatti, R A; Lenoir, G; Lavin, M F; Tatsumi, K; Wegner, R D; Shiloh, Y; Bar-Shira, A
1996-04-01
Ataxia-telangiectasia (A-T) is an autosomal recessive disorder involving cerebellar degeneration, immunodeficiency, chromosomal instability, radiosensitivity and cancer predisposition. The responsible gene, ATM, was recently identified by positional cloning and found to encode a putative 350 kDa protein with a Pl 3-kinase-like domain, presumably involved in mediating cell cycle arrest in response to radiation-induced DNA damage. The nature and location of A-T mutations should provide insight into the function of the ATM protein and the molecular basis of this pleiotropic disease. Of 44 A-T mutations identified by us to date, 39 (89%) are expected to inactivate the ATM protein by truncating it, by abolishing correct initiation or termination of translation, or by deleting large segments. Additional mutations are four smaller in-frame deletions and insertions, and one substitution of a highly conserved amino acid at the Pl 3-kinase domain. The emerging profile of mutations causing A-T is thus dominated by those expected to completely inactivate the ATM protein. ATM mutations with milder effects may result in phenotypes related, but not identical, to A-T.
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High frequency generation in the corona: Resonant cavities
NASA Astrophysics Data System (ADS)
Santamaria, I. C.; Van Doorsselaere, T.
2018-03-01
Aims: Null points are prominent magnetic field singularities in which the magnetic field strength strongly decreases in very small spatial scales. Around null points, predicted to be ubiquitous in the solar chromosphere and corona, the wave behavior changes considerably. Null points are also responsible for driving very energetic phenomena, and for contributing to chromospheric and coronal heating. In previous works we demonstrated that slow magneto-acoustic shock waves were generated in the chromosphere propagate through the null point, thereby producing a train of secondary shocks escaping along the field lines. A particular combination of the shock wave speeds generates waves at a frequency of 80 MHz. The present work aims to investigate this high frequency region around a coronal null point to give a plausible explanation to its generation at that particular frequency. Methods: We carried out a set of two-dimensional numerical simulations of wave propagation in the neighborhood of a null point located in the corona. We varied both the amplitude of the driver and the atmospheric properties to investigate the sensitivity of the high frequency waves to these parameters. Results: We demonstrate that the wave frequency is sensitive to the atmospheric parameters in the corona, but it is independent of the strength of the driver. Thus, the null point behaves as a resonant cavity generating waves at specific frequencies that depend on the background equilibrium model. Moreover, we conclude that the high frequency wave train generated at the null point is not necessarily a result of the interaction between the null point and a shock wave. This wave train can be also developed by the interaction between the null point and fast acoustic-like magneto-acoustic waves, that is, this interaction within the linear regime.
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Altered fronto-striatal functions in the Gdi1-null mouse model of X-linked Intellectual Disability.
Morè, Lorenzo; Künnecke, Basil; Yekhlef, Latefa; Bruns, Andreas; Marte, Antonella; Fedele, Ernesto; Bianchi, Veronica; Taverna, Stefano; Gatti, Silvia; D'Adamo, Patrizia
2017-03-06
RAB-GDP dissociation inhibitor 1 (GDI1) loss-of-function mutations are responsible for a form of non-specific X-linked Intellectual Disability (XLID) where the only clinical feature is cognitive impairment. GDI1 patients are impaired in specific aspects of executive functions and conditioned response, which are controlled by fronto-striatal circuitries. Previous molecular and behavioral characterization of the Gdi1-null mouse revealed alterations in the total number/distribution of hippocampal and cortical synaptic vesicles as well as hippocampal short-term synaptic plasticity, and memory deficits. In this study, we employed cognitive protocols with high translational validity to human condition that target the functionality of cortico-striatal circuitry such as attention and stimulus selection ability with progressive degree of complexity. We previously showed that Gdi1-null mice are impaired in some hippocampus-dependent forms of associative learning assessed by aversive procedures. Here, using appetitive-conditioning procedures we further investigated associative learning deficits sustained by the fronto-striatal system. We report that Gdi1-null mice are impaired in attention and associative learning processes, which are a key part of the cognitive impairment observed in XLID patients. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.
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Wong, Pauline; Colucci-Guyon, Emma; Takahashi, Kenzo; Gu, Changhong; Babinet, Charles; Coulombe, Pierre A.
2000-01-01
Mammalian genomes feature multiple genes encoding highly related keratin 6 (K6) isoforms. These type II keratins show a complex regulation with constitutive and inducible components in several stratified epithelia, including the oral mucosa and skin. Two functional genes, K6α and K6β, exist in a head-to-tail tandem array in mouse genomes. We inactivated these two genes simultaneously via targeting and homologous recombination. K6 null mice are viable and initially indistinguishable from their littermates. Starting at two to three days after birth, they show a growth delay associated with reduced milk intake and the presence of white plaques in the posterior region of dorsal tongue and upper palate. These regions are subjected to greater mechanical stress during suckling. Morphological analyses implicate the filiform papillae as being particularly sensitive to trauma in K6α/K6β null mice, and establish the complete absence of keratin filaments in their anterior compartment. All null mice die about a week after birth. These studies demonstrate an essential structural role for K6 isoforms in the oral mucosa, and implicate filiform papillae as being the major stress bearing structures in dorsal tongue epithelium. PMID:10953016
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Khan, Sharik R; Farrand, Stephen K
2009-02-01
The conjugative transfer of Agrobacterium plasmids is controlled by a quorum-sensing system consisting of TraR and its acyl-homoserine lactone (HSL) ligand. The acyl-HSL is essential for the TraR-mediated activation of the Ti plasmid Tra genes. Strains A6 and C58 of Agrobacterium tumefaciens produce a lactonase, BlcC (AttM), that can degrade the quormone, leading some to conclude that the enzyme quenches the quorum-sensing system. We tested this hypothesis by examining the effects of the mutation, induction, or mutational derepression of blcC on the accumulation of acyl-HSL and on the conjugative competence of strain C58. The induction of blc resulted in an 8- to 10-fold decrease in levels of extracellular acyl-HSL but in only a twofold decrease in intracellular quormone levels, a measure of the amount of active intracellular TraR. The induction or mutational derepression of blc as well as a null mutation in blcC had no significant effect on the induction of or continued transfer of pTiC58 from donors in any stage of growth, including stationary phase. In matings performed in developing tumors, wild-type C58 transferred the Ti plasmid to recipients, yielding transconjugants by 14 to 21 days following infection. blcC-null donors yielded transconjugants 1 week earlier, but by the following week, transconjugants were recovered at numbers indistinguishable from those of the wild type. Donors mutationally derepressed for blcC yielded transconjugants in planta at numbers 10-fold lower than those for the wild type at weeks 2 and 3, but by week 4, the two donors showed no difference in recoverable transconjugants. We conclude that BlcC has no biologically significant effect on Ti plasmid transfer or its regulatory system.
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USDA-ARS?s Scientific Manuscript database
Ozone uptake by plants leads to an increase in reactive oxygen species (ROS) in the intercellular space of leaves and induces signalling processes reported to involve the membrane-bound heterotrimeric G-protein complex. Therefore, potential G-protein-mediated response mechanisms to ozone were compar...
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Brief Report: Altered Social Behavior in Isolation-Reared "Fmr1" Knockout Mice
ERIC Educational Resources Information Center
Heitzer, Andrew M.; Roth, Alexandra K.; Nawrocki, Lauren; Wrenn, Craige C.; Valdovinos, Maria G.
2013-01-01
Social behavior abnormalities in Fragile X syndrome (FXS) are characterized by social withdrawal, anxiety, and deficits in social cognition. To assess these deficits, a model of FXS, the "Fmr1" knockout mouse ("Fmr1" KO), has been utilized. This mouse model has a null mutation in the fragile X mental retardation 1 gene ("Fmr1") and displays…
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Kobayashi, Sumitaka; Sata, Fumihiro; Miyashita, Chihiro; Sasaki, Seiko; Ban, Susumu; Araki, Atsuko; Goudarzi, Houman; Kajiwara, Jumboku; Todaka, Takashi; Kishi, Reiko
2017-01-01
We investigated the effects of maternal polymorphisms in 3 genes encoding dioxin-metabolizing enzymes in relation to prenatal dioxin levels on infant birth size in Japan. We examined the relationship between dioxin exposure and birth size in relation to the polymorphisms in the genes encoding aromatic hydrocarbon receptor (AHR [G>A, Arg554Lys]), cytochrome P450 (CYP) 1A1 (T6235C), and glutathione S-transferase mu 1 (GSTM1; Non-null/null) in 421 participants using multiple linear regression models. In mothers carrying the GSTM1 null genotype, a ten-fold increase in total dioxin toxic equivalency was correlated with a decrease in birth weight of -345g (95% confidence interval: -584, -105). We observed adverse effects of maternal GSTM1 null genotype on birth weight in the presence of dioxins exposure during pregnancy. Copyright © 2016 Elsevier Inc. All rights reserved.
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Tseng, Hsiang-Kuang; Liu, Chang-Pan; Price, Michael S.; Jong, Ambrose Y.; Chang, Jui-Chih; Toffaletti, Dena L.; Betancourt-Quiroz, Marisol; Frazzitta, Aubrey E.; Cho, Wen-Long; Perfect, John R.
2012-01-01
Background A mouse brain transmigration assessment (MBTA) was created to investigate the central nervous system (CNS) pathogenesis of cryptococcal meningoencephalitis. Methodology/Principal Findings Two cryptococcal mutants were identified from a pool of 109 pre-selected mutants that were signature-tagged with the nourseothricin acetyltransferase (NAT) resistance cassette. These two mutants displayed abnormal transmigration into the central nervous system. One mutant displaying decreased transmigration contains a null mutation in the putative FNX1 gene, whereas the other mutant possessing a null mutation in the putative RUB1 gene exhibited increased transmigration into the brain. Two macrophage adhesion-defective mutants in the pool, 12F1 and 3C9, showed reduced phagocytosis by macrophages, but displayed no defects in CNS entry suggesting that transit within macrophages (the “Trojan horse” model of CNS entry) is not the primary mechanism for C. neoformans migration into the CNS in this MBTA. Conclusions/Significance This research design provides a new strategy for genetic impact studies on how Cryptococcus passes through the blood-brain barrier (BBB), and the specific isolated mutants in this assay support a transcellular mechanism of CNS entry. PMID:23028773
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Henderson, Ian R; Liu, Fuquan; Drea, Sinead; Simpson, Gordon G; Dean, Caroline
2005-08-01
The autonomous pathway functions to promote flowering in Arabidopsis by limiting the accumulation of the floral repressor FLOWERING LOCUS C (FLC). Within this pathway FCA is a plant-specific, nuclear RNA-binding protein, which interacts with FY, a highly conserved eukaryotic polyadenylation factor. FCA and FY function to control polyadenylation site choice during processing of the FCA transcript. Null mutations in the yeast FY homologue Pfs2p are lethal. This raises the question as to whether these essential RNA processing functions are conserved in plants. Characterisation of an allelic series of fy mutations reveals that null alleles are embryo lethal. Furthermore, silencing of FY, but not FCA, is deleterious to growth in Nicotiana. The late-flowering fy alleles are hypomorphic and indicate a requirement for both intact FY WD repeats and the C-terminal domain in repression of FLC. The FY C-terminal domain binds FCA and in vitro assays demonstrate a requirement for both C-terminal FY-PPLPP repeats during this interaction. The expression domain of FY supports its roles in essential and flowering-time functions. Hence, FY may mediate both regulated and constitutive RNA 3'-end processing.
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Horn, Thomas; Ivanov, Igor; Di Venere, Almerinda; Kakularam, Kumar Reddy; Reddanna, Pallu; Conrad, Melanie L; Richter, Constanze; Scheerer, Patrick; Kuhn, Hartmut
2013-12-01
Mammalian lipoxygenases belong to a family of lipid-peroxidizing enzymes, which have been implicated in cardiovascular, hyperproliferative and neurodegenerative diseases. Here we report that a naturally occurring mutation in the hALOX15 gene leads to expression of a catalytically near-null enzyme variant (hGly422Glu). The inactivity may be related to severe misfolding of the enzyme protein, which was concluded from CD-spectra as well as from thermal and chemical stability assays. In silico mutagenesis experiments suggest that most mutations at hGly422 have the potential to induce sterical clash, which might be considered a reason for protein misfolding. hGly422 is conserved among ALOX5, ALOX12 and ALOX15 isoforms and corresponding hALOX12 and hALOX5 mutants also exhibited a reduced catalytic activity. Interestingly, in the hALOX5 Gly429Glu mutants the reaction specificity of arachidonic acid oxygenation was shifted from 5S- to 8S- and 12R-H(p)ETE formation. Taken together, our data indicate that the conserved glycine is of functional importance for these enzyme variants and most mutants at this position lose catalytic activity. © 2013.
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2016-01-01
Virus homologues of seven-transmembrane receptors (7TMR) are encoded by all beta- and gammaherpesviruses, suggesting important functional roles. M78 of mouse cytomegalovirus (MCMV) is representative of a family of 7TMR conserved in all betaherpesviruses. M78 family members have been found to exhibit cell-type specific effects upon virus replication in tissue culture and to affect virus pathogenesis in vivo. We reported previously that M78, for which no ligands are known, undergoes rapid, constitutive endocytosis. In this study, we have investigated the role of the M78 cytoplasmic C-tail in mediating endocytosis and consequences of C-tail deletion upon replication and pathogenesis. Mutations of M78 (C-tail truncations or point mutations) and CCR5-M78 chimeras identified two distinct regions affecting endocytosis. The first was a classical acidic di-leucine motif (DDxxxLL), located close to the C-terminus. The second region, the activity of which was suppressed by downstream sequences, included the putative 8th helix, located close to the 7th transmembrane domain. A recombinant MCMV expressing an endocytosis-deficient M78, lacking most of the C-tail (M78_CΔ155), had a cell-type specific replication phenotype. M78_CΔ155 had restricted replication in bone marrow macrophages, indistinguishable from an M78-null recombinant. In contrast, M78_CΔ155 replicated normally or with enhanced titres to wild type virus in other tested cell-types, whereas M78-null was attenuated. Distinct phenotypes for M78_CΔ155 and M78-null suggest that the C-tail deletion resulted in M78 dysfunction, rather than complete loss of function; furthermore, they highlight a cell-type specific role of M78 during replication. Infection of mice (intranasal) demonstrated that M78_CΔ155, similar to M78-null, was cleared more rapidly from the lungs than wild type virus and was severely attenuated for replication in salivary glands. It may be speculated that attenuation of both M78_CΔ155 and M78-null for replication in macrophages may have contributed to their similar pathogenic phenotypes. PMID:27760189
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Usongo, Valentine; Martel, Makisha; Balleydier, Aurélien; Drolet, Marc
2016-04-01
R-loop formation occurs when the nascent RNA hybridizes with the template DNA strand behind the RNA polymerase. R-loops affect a wide range of cellular processes and their use as origins of replication was the first function attributed to them. In Escherichia coli, R-loop formation is promoted by the ATP-dependent negative supercoiling activity of gyrase (gyrA and gyrB) and is inhibited by topoisomerase (topo) I (topA) relaxing transcription-induced negative supercoiling. RNase HI (rnhA) degrades the RNA moiety of R-loops. The depletion of RNase HI activity in topA null mutants was previously shown to lead to extensive DNA relaxation, due to DNA gyrase inhibition, and to severe growth and chromosome segregation defects that were partially corrected by overproducing topo III (topB). Here, DNA gyrase assays in crude cell extracts showed that the ATP-dependent activity (supercoiling) of gyrase but not its ATP-independent activity (relaxation) was inhibited in topA null cells lacking RNase HI. To characterize the cellular event(s) triggered by the absence of RNase HI, we performed a genetic screen for suppressors of the growth defect of topA rnhA null cells. Suppressors affecting genes in replication (holC2::aph and dnaT18::aph) nucleotide metabolism (dcd49::aph), RNA degradation (rne59::aph) and fimbriae synthesis (fimD22::aph) were found to reduce replication from R-loops and to restore supercoiling, thus pointing to a correlation between R-loop-dependent replication in topA rnhA mutants and the inhibition of gyrase activity and growth. Interestingly, the position of fimD on the E. coli chromosome corresponds to the site of one of the five main putative origins of replication from R-loops in rnhA null cells recently identified by next-generation sequencing, thus suggesting that the fimD22::aph mutation inactivated one of these origins. Furthermore, we show that topo III overproduction is unable to complement the growth defect of topA rnhA null mutants at low temperatures that stabilizes hyper-negatively supercoiled DNA. Copyright © 2016 Elsevier B.V. All rights reserved.
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Borbon, Ivan; Campbell, Erin; Ke, Wangjing; Erickson, Robert P
2012-08-01
We have previously shown that decreased dosage of Niemann-Pick C1 (Npc1) protein, caused by heterozygosity at the null mutation, Npc1 (nih), locus, causes altered lipid metabolism in mice. When studied on the "lean" BALB/cJ genetic background, the decreased protein was associated with no weight changes in either males or females when on a regular diet but increased weights and adiposity when on a high fat diet Jelinek et al. (Obesity 18: 1457-1459, 2010, Gene 491:128-134, 2012). When the heterozygotes were studied on a mixed C57BL/6J, BALB/cJ background, increased weight and adiposity were also found on a regular diet (sexes pooled Jelinek et al. [Hum Molec Genet 20:312-321, 2011]). We find somewhat different results when the hypomorphic Npc1 mutation, Npc1 (nmf164), is studied on a pure C57BL/6J, "metabolic syndrome" genetic background with male, but not female, heterozygotes having lower weights on the regular diet. The result does not seem to be due to the difference in the two mutations as heterozygous Npc1 (nmf164) mice on the BALB/cJ background acted like the null mutant heterozygotes. Studies of glucose tolerance, liver enzymes, liver triglycerides and fat deposition, and adipose tissue caveolin 1 levels did not disclose reasons for these differing results.
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A Defect in DNA Ligase4 Enhances the Frequency of TALEN-Mediated Targeted Mutagenesis in Rice1[OPEN
Cermak, Tomas; Sugimoto, Kazuhiko; Saika, Hiroaki; Mori, Akiko; Osakabe, Keishi; Hamada, Masao; Katayose, Yuichi; Voytas, Daniel F.
2016-01-01
We have established methods for site-directed mutagenesis via transcription activator-like effector nucleases (TALENs) in the endogenous rice (Oryza sativa) waxy gene and demonstrated stable inheritance of TALEN-induced somatic mutations to the progeny. To analyze the role of classical nonhomologous end joining (cNHEJ) and alternative nonhomologous end joining (altNHEJ) pathways in TALEN-induced mutagenesis in plant cells, we investigated whether a lack of DNA Ligase4 (Lig4) affects the kinetics of TALEN-induced double-strand break repair in rice cells. Deep-sequencing analysis revealed that the frequency of all types of mutations, namely deletion, insertion, combination of insertion with deletion, and substitution, in lig4 null mutant calli was higher than that in a lig4 heterozygous mutant or the wild type. In addition, the ratio of large deletions (greater than 10 bp) and deletions repaired by microhomology-mediated end joining (MMEJ) to total deletion mutations in lig4 null mutant calli was higher than that in the lig4 heterozygous mutant or wild type. Furthermore, almost all insertions (2 bp or greater) were shown to be processed via copy and paste of one or more regions around the TALENs cleavage site and rejoined via MMEJ regardless of genetic background. Taken together, our findings indicate that the dysfunction of cNHEJ leads to a shift in the repair pathway from cNHEJ to altNHEJ or synthesis-dependent strand annealing. PMID:26668331
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Sun, Xuejing; Xing, Xinli; He, Qingqing; Zhou, Lin; Zhang, Jing; Zhao, Qing; Hou, Huili; Xi, Zuoming
2017-10-10
To assess the value of pre-gestational deafness-related mutation screening for the prevention and intervention of congenital deafness. In this study, 2168 couples with normal hearing were screened for common mutations associated with congenital deafness using real-time fluorescence quantitative PCR. The mutations have included GJB2 c.235delC and c.299_300delAT, SLC26A4 c.2168A>G and c.IVS7-2A>G, and mtDNA 12SrRNA c.1494C>T and c.1555A>G. For couples who have both carried heterozygous mutations of the same gene, genetic counseling and prenatal diagnosis were provided. Among of the 4 336 individuals, 178 (4.06%) were found to carry a mutation. Mutation rate for c.235delC and c.299_300delAT of GJB2 gene, c.IVS7-2 A>G and c.2168 A>G of SLC26A4 gene, c.1555 A>G and c.1494 C>T of DNA 12S rRNA gene were 0.91%, 0.20%, 0.68%, 0.11%, 0.1% and 0.01%, respectively. For six couples who have both carried mutations of the same gene, all fetuses showed a normal karyotype, while DNA sequencing indicated that two fetuses have carried homozygous c.235delC mutation of the GJB2 gene, one carried a heterozygous c.235delC mutation of the GJB2 gene, one carried heterozygous mutation of GJB2 gene (c.299_300delAT), and two have carried a heterozygous mutation of c.IVS7-2A>G of the SLC26A4 gene. Pre-gestational screening for deafness gene mutation can facilitate avoidance the birth of affected children and has a great clinical value for the prevention and intervention of birth defect.
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Collins, Carol M.; Ellis, Joseph A.
2017-01-01
ABSTRACT Mutations in the gene encoding emerin cause Emery–Dreifuss muscular dystrophy (EDMD). Emerin is an integral inner nuclear membrane protein and a component of the nuclear lamina. EDMD is characterized by skeletal muscle wasting, cardiac conduction defects and tendon contractures. The failure to regenerate skeletal muscle is predicted to contribute to the skeletal muscle pathology of EDMD. We hypothesize that muscle regeneration defects are caused by impaired muscle stem cell differentiation. Myogenic progenitors derived from emerin-null mice were used to confirm their impaired differentiation and analyze selected myogenic molecular pathways. Emerin-null progenitors were delayed in their cell cycle exit, had decreased myosin heavy chain (MyHC) expression and formed fewer myotubes. Emerin binds to and activates histone deacetylase 3 (HDAC3). Here, we show that theophylline, an HDAC3-specific activator, improved myotube formation in emerin-null cells. Addition of the HDAC3-specific inhibitor RGFP966 blocked myotube formation and MyHC expression in wild-type and emerin-null myogenic progenitors, but did not affect cell cycle exit. Downregulation of emerin was previously shown to affect the p38 MAPK and ERK/MAPK pathways in C2C12 myoblast differentiation. Using a pure population of myogenic progenitors completely lacking emerin expression, we show that these pathways are also disrupted. ERK inhibition improved MyHC expression in emerin-null cells, but failed to rescue myotube formation or cell cycle exit. Inhibition of p38 MAPK prevented differentiation in both wild-type and emerin-null progenitors. These results show that each of these molecular pathways specifically regulates a particular stage of myogenic differentiation in an emerin-dependent manner. Thus, pharmacological targeting of multiple pathways acting at specific differentiation stages may be a better therapeutic approach in the future to rescue muscle regeneration in vivo. PMID:28188262
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Creemers, John W.M.; Choquet, Hélène; Stijnen, Pieter; Vatin, Vincent; Pigeyre, Marie; Beckers, Sigri; Meulemans, Sandra; Than, Manuel E.; Yengo, Loïc; Tauber, Maithé; Balkau, Beverley; Elliott, Paul; Jarvelin, Marjo-Riitta; Van Hul, Wim; Van Gaal, Luc; Horber, Fritz; Pattou, François; Froguel, Philippe; Meyre, David
2012-01-01
Null mutations in the PCSK1 gene, encoding the proprotein convertase 1/3 (PC1/3), cause recessive monogenic early onset obesity. Frequent coding variants that modestly impair PC1/3 function mildly increase the risk for common obesity. The aim of this study was to determine the contribution of rare functional PCSK1 mutations to obesity. PCSK1 exons were sequenced in 845 nonconsanguineous extremely obese Europeans. Eight novel nonsynonymous PCSK1 mutations were identified, all heterozygous. Seven mutations had a deleterious effect on either the maturation or the enzymatic activity of PC1/3 in cell lines. Of interest, five of these novel mutations, one of the previously described frequent variants (N221D), and the mutation found in an obese mouse model (N222D), affect residues at or near the structural calcium binding site Ca-1. The prevalence of the newly identified mutations was assessed in 6,233 obese and 6,274 lean European adults and children, which showed that carriers of any of these mutations causing partial PCSK1 deficiency had an 8.7-fold higher risk to be obese than wild-type carriers. These results provide the first evidence of an increased risk of obesity in heterozygous carriers of mutations in the PCSK1 gene. Furthermore, mutations causing partial PCSK1 deficiency are present in 0.83% of extreme obesity phenotypes. PMID:22210313
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Creemers, John W M; Choquet, Hélène; Stijnen, Pieter; Vatin, Vincent; Pigeyre, Marie; Beckers, Sigri; Meulemans, Sandra; Than, Manuel E; Yengo, Loïc; Tauber, Maithé; Balkau, Beverley; Elliott, Paul; Jarvelin, Marjo-Riitta; Van Hul, Wim; Van Gaal, Luc; Horber, Fritz; Pattou, François; Froguel, Philippe; Meyre, David
2012-02-01
Null mutations in the PCSK1 gene, encoding the proprotein convertase 1/3 (PC1/3), cause recessive monogenic early onset obesity. Frequent coding variants that modestly impair PC1/3 function mildly increase the risk for common obesity. The aim of this study was to determine the contribution of rare functional PCSK1 mutations to obesity. PCSK1 exons were sequenced in 845 nonconsanguineous extremely obese Europeans. Eight novel nonsynonymous PCSK1 mutations were identified, all heterozygous. Seven mutations had a deleterious effect on either the maturation or the enzymatic activity of PC1/3 in cell lines. Of interest, five of these novel mutations, one of the previously described frequent variants (N221D), and the mutation found in an obese mouse model (N222D), affect residues at or near the structural calcium binding site Ca-1. The prevalence of the newly identified mutations was assessed in 6,233 obese and 6,274 lean European adults and children, which showed that carriers of any of these mutations causing partial PCSK1 deficiency had an 8.7-fold higher risk to be obese than wild-type carriers. These results provide the first evidence of an increased risk of obesity in heterozygous carriers of mutations in the PCSK1 gene. Furthermore, mutations causing partial PCSK1 deficiency are present in 0.83% of extreme obesity phenotypes.
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Abbas, Shania; Raza, Syed Tasleem; Chandra, Anu; Rizvi, Saliha; Ahmed, Faisal; Eba, Ale; Mahdi, Farzana
2015-01-01
Hypertension has a multi-factorial background based on genetic and environmental interactive factors. ACE, FABP2 and GST genes have been suggested to be involved in the development of hypertension. However, the results have been inconsistent. The present study was carried out to investigate the association of ACE (rs4646994), FABP2 (rs1799883) and GST (GSTM1 null or positive genotype and GSTT1 null or positive genotype) genes polymorphism with essential HTN cases and controls. This study includes 138 essential hypertension (HTN) patients and 116 age-, sex- and ethnicity-matched control subjects. GST (GSTM1 null or positive genotype and GSTT1 null or positive genotype) genes polymorphisms were evaluated by multiplex PCR, ACE (rs4646994) gene polymorphisms by PCR and FABP2 (rs1799883) gene polymorphisms by PCR-RFLP method. Significant differences were obtained in the frequencies of ACE DD, II genotype (p = 0.006, 0.003), GSTT1 null, GSTM1 positive genotype (p = 0.048, 0.010) and FABP2 Ala54/Ala54 genotype (p = 0.049) between essential HTN cases and controls. It is concluded that ACE (rs 4646994), FABP2 (rs1799883) and GST (GSTM1 null or positive genotype and GSTT1 null or positive genotype) genes polymorphism are associated with HTN. Further investigation with a larger sample size may be required to validate this study.
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Krone, Nils; Rose, Ian T.; Willis, Debbie S.; Hodson, James; Wild, Sarah H.; Doherty, Emma J.; Hahner, Stefanie; Parajes, Silvia; Stimson, Roland H.; Han, Thang S.; Carroll, Paul V.; Conway, Gerry S.; Walker, Brian R.; MacDonald, Fiona; Arlt, Wiebke
2013-01-01
Context: In congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, a strong genotype-phenotype correlation exists in childhood. However, similar data in adults are lacking. Objective: The objective of the study was to test whether the severity of disease-causing CYP21A2 mutations influences the treatment and health status in adults with CAH. Research Design and Methods: We analyzed the genotype in correlation with treatment and health status in 153 adults with CAH from the United Kingdom Congenital adrenal Hyperplasia Adult Study Executive cohort. Results: CYP21A2 mutations were distributed similarly to previously reported case series. In 7 patients a mutation was identified on only 1 allele. Novel mutations were detected on 1.7% of alleles (5 of 306). Rare mutations were found on 2.3% of alleles (7 of 306). For further analysis, patients were categorized into CYP21A2 mutation groups according to predicted residual enzyme function: null (n = 34), A (n = 42), B (n = 36), C (n = 34), and D (n = 7). Daily glucocorticoid dose was highest in group null and lowest in group C. Fludrocortisone was used more frequently in patients with more severe genotypes. Except for lower female height in group B, no statistically significant associations between genotype and clinical parameters were found. Androgens, blood pressure, lipids, blood glucose, and homeostasis model assessment of insulin resistance were not different between groups. Subjective health status was similarly impaired across groups. Conclusions: In adults with classic CAH and women with nonclassic CAH, there was a weak association between genotype and treatment, but health outcomes were not associated with genotype. The underrepresentation of males with nonclassic CAH may reflect that milder genotypes result in a milder condition that is neither diagnosed nor followed up in adulthood. Overall, our results suggest that the impaired health status of adults with CAH coming to medical attention is acquired rather than genetically determined and therefore could potentially be improved through modification of treatment. PMID:23337727
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Functional Rescue of Trafficking-Impaired ABCB4 Mutants by Chemical Chaperones
Gordo-Gilart, Raquel; Andueza, Sara; Hierro, Loreto; Jara, Paloma; Alvarez, Luis
2016-01-01
Multidrug resistance protein 3 (MDR3, ABCB4) is a hepatocellular membrane protein that mediates biliary secretion of phosphatidylcholine. Null mutations in ABCB4 gene give rise to severe early-onset cholestatic liver disease. We have previously shown that the disease-associated mutations p.G68R, p.G228R, p.D459H, and p.A934T resulted in retention of ABCB4 in the endoplasmic reticulum, thus failing to target the plasma membrane. In the present study, we tested the ability of two compounds with chaperone-like activity, 4-phenylbutyrate and curcumin, to rescue these ABCB4 mutants by assessing their effects on subcellular localization, protein maturation, and phospholipid efflux capability. Incubation of transfected cells at a reduced temperature (30°C) or exposure to pharmacological doses of either 4-PBA or curcumin restored cell surface expression of mutants G228R and A934T. The delivery of these mutants to the plasma membrane was accompanied by a switch in the ratio of mature to inmature protein forms, leading to a predominant expression of the mature protein. This effect was due to an improvement in the maturation rate and not to the stabilization of the mature forms. Both mutants were also functionally rescued, displaying bile salt-dependent phospholipid efflux activity after addition of 4-PBA or curcumin. Drug-induced rescue was mutant specific, given neither 4-PBA nor curcumin had an effect on the ABCB4 mutants G68R and A934T. Collectively, these data indicate that the functionality of selected trafficking-defective ABCB4 mutants can be recovered by chemical chaperones through restoration of membrane localization, suggesting a potential treatment for patients carrying such mutations. PMID:26900700
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A ‘synthetic-sickness’ screen for senescence re-engagement targets in mutant cancer backgrounds
Godwin, Lauren S.; Bilsland, Alan E.; Stevenson, Katrina H.; Moore, Jon D.; Wiggins, Ceri M.; Collinson, Rebecca S.; Mudd, Clare; Sadaie, Mahito; Bennett, Dorothy C.; Torrance, Christopher J.; Keith, W. Nicol
2017-01-01
Senescence is a universal barrier to immortalisation and tumorigenesis. As such, interest in the use of senescence-induction in a therapeutic context has been gaining momentum in the past few years; however, senescence and immortalisation remain underserved areas for drug discovery owing to a lack of robust senescence inducing agents and an incomplete understanding of the signalling events underlying this complex process. In order to address this issue we undertook a large-scale morphological siRNA screen for inducers of senescence phenotypes in the human melanoma cell line A375P. Following rescreen and validation in a second cancer cell line, HCT116 colorectal carcinoma, a panel of 16 of the most robust hits were selected for further validation based on significance and the potential to be targeted by drug-like molecules. Using secondary assays for detection of senescence biomarkers p21, 53BP1 and senescence associated beta-galactosidase (SAβGal) in a panel of HCT116 cell lines carrying cancer-relevant mutations, we show that partial senescence phenotypes can be induced to varying degrees in a context dependent manner, even in the absence of p21 or p53 expression. However, proliferation arrest varied among genetic backgrounds with predominantly toxic effects in p21 null cells, while cells lacking PI3K mutation failed to arrest. Furthermore, we show that the oncogene ECT2 induces partial senescence phenotypes in all mutant backgrounds tested, demonstrating a dependence on activating KRASG13D for growth suppression and a complete senescence response. These results suggest a potential mechanism to target mutant KRAS signalling through ECT2 in cancers that are reliant on activating KRAS mutations and remain refractory to current treatments. PMID:28806777
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Geng, Ruishuang; Melki, Sami; Chen, Daniel H.-C.; Tian, Guilian; Furness, David; Oshima-Takago, Tomoko; Neef, Jakob; Moser, Tobias; Askew, Charles; Horwitz, Geoff; Holt, Jeffrey; Imanishi, Yoshikazu; Alagramam, Kumar N.
2012-01-01
Mutation in the clarin-1 gene results in loss of hearing and vision in humans (Usher syndrome III), but the role of clarin-1 in the sensory hair cells is unknown. Clarin-1 is predicted to be a four transmembrane domain protein similar to members of the tetraspanin family. Mice carrying null mutation in the clarin-1 (Clrn1−/−) gene show loss of hair cell function and a possible defect in ribbon synapse. We investigated the role of clarin-1 using various in vitro and in vivo approaches. We show by immunohistochemistry and patch-clamp recordings of Ca2+ currents and membrane capacitance from IHCs that clarin-1 is not essential for formation or function of ribbon synapse. However, reduced cochlear microphonic potentials, FM1-43 loading and transduction currents pointed to diminished cochlear hair bundle function in Clrn1−/− mice. Electron microscopy of cochlear hair cells revealed loss of some tall stereocilia and gaps in the v-shaped bundle, although tip-links and staircase arrangement of stereocilia were not primarily affected by Clrn1−/− mutation. Human clarin-1 protein expressed in transfected mouse cochlear hair cells localized to the bundle; however, the pathogenic variant, p.N48K, failed to localize to the bundle. The mouse model generated to study the in vivo consequence of p. N48K in clarin-1 (Clrn1N48K) supports our in vitro and Clrn1−/− mouse data and the conclusion that CLRN1 is an essential hair bundle protein. Further, the ear phenotype in the Clrn1N48K mouse suggests that it is a valuable model for ear disease in CLRN1N48K, the most prevalent Usher III mutation in North America. PMID:22787034
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Geng, Ruishuang; Melki, Sami; Chen, Daniel H-C; Tian, Guilian; Furness, David N; Oshima-Takago, Tomoko; Neef, Jakob; Moser, Tobias; Askew, Charles; Horwitz, Geoff; Holt, Jeffrey R; Imanishi, Yoshikazu; Alagramam, Kumar N
2012-07-11
Mutation in the clarin-1 gene (Clrn1) results in loss of hearing and vision in humans (Usher syndrome III), but the role of clarin-1 in the sensory hair cells is unknown. Clarin-1 is predicted to be a four transmembrane domain protein similar to members of the tetraspanin family. Mice carrying null mutation in the clarin-1 gene (Clrn1(-/-)) show loss of hair cell function and a possible defect in ribbon synapse. We investigated the role of clarin-1 using various in vitro and in vivo approaches. We show by immunohistochemistry and patch-clamp recordings of Ca(2+) currents and membrane capacitance from inner hair cells that clarin-1 is not essential for formation or function of ribbon synapse. However, reduced cochlear microphonic potentials, FM1-43 [N-(3-triethylammoniumpropyl)-4-(4-(dibutylamino)styryl) pyridinium dibromide] loading, and transduction currents pointed to diminished cochlear hair bundle function in Clrn1(-/-) mice. Electron microscopy of cochlear hair cells revealed loss of some tall stereocilia and gaps in the v-shaped bundle, although tip links and staircase arrangement of stereocilia were not primarily affected by Clrn1(-/-) mutation. Human clarin-1 protein expressed in transfected mouse cochlear hair cells localized to the bundle; however, the pathogenic variant p.N48K failed to localize to the bundle. The mouse model generated to study the in vivo consequence of p.N48K in clarin-1 (Clrn1(N48K)) supports our in vitro and Clrn1(-/-) mouse data and the conclusion that CLRN1 is an essential hair bundle protein. Furthermore, the ear phenotype in the Clrn1(N48K) mouse suggests that it is a valuable model for ear disease in CLRN1(N48K), the most prevalent Usher syndrome III mutation in North America.
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Xie, Yufen; Wang, Yingchun; Sun, Tong; Wang, Fangfei; Trostinskaia, Anna; Puscheck, Elizabeth; Rappolee, Daniel A
2005-05-01
Mitogen-activated protein kinase (MAPK) signaling pathways play an important role in controlling embryonic proliferation and differentiation. It has been demonstrated that sequential lipophilic signal transduction mediators that participate in the MAPK pathway are null post-implantation lethal. It is not clear why the lethality of these null mutants arises after implantation and not before. One hypothesis is that the gene product of these post-implantation lethal null mutants are not present before implantation in normal embryos and do not have function until after implantation. To test this hypothesis, we selected a set of lipophilic genes mediating MAPK signal transduction pathways whose null mutants result in early peri-implantation or placental lethality. These included FRS2alpha, GAB1, GRB2, SOS1, Raf-B, and Raf1. Products of these selected genes were detected and their locations and functions indicated by indirect immunocytochemistry and Western blotting for proteins and RT-polymerase chain reaction (PCR) for mRNA transcription. We report here that all six signal mediators are detected at the protein level in preimplantation mouse embryo, placental trophoblasts, and in cultured trophoblast stem cells (TSC). Proteins are all detected in E3.5 embryos at a time when the first known mitogenic intercellular communication has been documented. mRNA transcripts of two post-implantation null mutant genes are expressed in mouse preimplantation embryos and unfertilized eggs. These mRNA transcripts were detected as maternal mRNA in unfertilized eggs that could delay the lethality of null mutants. All of the proteins were detected in the cytoplasm or in the cell membrane. This study of spatial and temporal expression revealed that all of these six null mutants post-implantation genes in MAPK pathway are expressed and, where tested, phosphorylated/activated proteins are detected in the blastocyst. Studies on RNA expression using RT-PCR suggest that maternal RNA could play an important role in delaying the presence of the lethal phenotype of null mutations. Copyright (c) 2005 Wiley-Liss, Inc.
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Dmp1 Null Mice Develop a Unique Osteoarthritis-like Phenotype
Zhang, Qi; Lin, Shuxian; Liu, Ying; Yuan, Baozhi; Harris, Steph E; Feng, Jian Q.
2016-01-01
Patients with hypophosphatemia rickets (including DMP1 mutations) develop severe osteoarthritis (OA), although the mechanism is largely unknown. In this study, we first identified the expression of DMP1 in hypertrophic chondrocytes using immunohistochemistry (IHC) and X-gal analysis of Dmp1-knockout-lacZ-knockin heterozygous mice. Next, we characterized the OA-like phenotype in Dmp1 null mice from 7-week-old to one-year-old using multiple techniques, including X-ray, micro-CT, H&E staining, Goldner staining, scanning electronic microscopy, IHC assays, etc. We found a classical OA-like phenotype in Dmp1 null mice such as articular cartilage degradation, osteophyte formation, and subchondral osteosclerosis. These Dmp1 null mice also developed unique pathological changes, including a biphasic change in their articular cartilage from the initial expansion of hypertrophic chondrocytes at the age of 1-month to a quick diminished articular cartilage layer at the age of 3-months. Further, these null mice displayed severe enlarged knees and poorly formed bone with an expanded osteoid area. To address whether DMP1 plays a direct role in the articular cartilage, we deleted Dmp1 specifically in hypertrophic chondrocytes by crossing the Dmp1-loxP mice with Col X Cre mice. Interestingly, these conditional knockout mice didn't display notable defects in either the articular cartilage or the growth plate. Because of the hypophosphatemia remained in the entire life span of the Dmp1 null mice, we also investigated whether a high phosphate diet would improve the OA-like phenotype. A 8-week treatment of a high phosphate diet significantly rescued the OA-like defect in Dmp1 null mice, supporting the critical role of phosphate homeostasis in maintaining the healthy joint morphology and function. Taken together, this study demonstrates a unique OA-like phenotype in Dmp1 null mice, but a lack of the direct impact of DMP1 on chondrogenesis. Instead, the regulation of phosphate homeostasis by DMP1 via the axis of “FGF23-renal phosphorus reabsorption” is vital for maintaining a healthy joint. PMID:27766035
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Robinson, Nicholas P; McCulloch, Richard; Conway, Colin; Browitt, Alison; Barry, J David
2002-07-19
We demonstrate, by gene deletion analysis, that Mre11 has a critical role in maintaining genomic integrity in Trypanosoma brucei. mre11(-/-) null mutant strains exhibited retarded growth but no delay or disruption of cell cycle progression. They showed also a weak hyporecombination phenotype and the accumulation of gross chromosomal rearrangements, which did not involve sequence translocation, telomere loss, or formation of new telomeres. The trypanosome mre11(-/-) strains were hypersensitive to phleomycin, a mutagen causing DNA double strand breaks (DSBs) but, in contrast to mre11(-/-) null mutants in other organisms and T. brucei rad51(-/-) null mutants, displayed no hypersensitivity to methyl methanesulfonate, which causes point mutations and DSBs. Mre11 therefore is important for the repair of chromosomal damage and DSBs in trypanosomes, although in this organism the intersection of repair pathways appears to differ from that in other organisms. Mre11 inactivation appears not to affect VSG gene switching during antigenic variation of a laboratory strain, which is perhaps surprising given the importance of homologous recombination during this process.
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A Counterregulatory Mechanism Impacting Androgen Suppression Therapy
2016-08-01
to assess infection efficiency. The levels of key steroidogenic transcripts were monitored by qRT-PCR. Early genes in the testosterone biosynthetic...original copies of journal articles, reprints of manuscripts and abstracts, a curriculum vitae, patent applications, study questionnaires, and surveys ...gland (15, 16). Mice harboring germline homozygous null mutations in either Gata4 or Gata6 die early in embryonic develop- ment, so Cre-LoxP technology
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Dasgupta, Ujjaini; Dixit, Bharat L; Rusch, Melissa; Selleck, Scott; The, Inge
2007-08-01
Heparan sulfate proteoglycans play a vital role in signaling of various growth factors in both Drosophila and vertebrates. In Drosophila, mutations in the tout velu (ttv) gene, a homolog of the mammalian EXT1 tumor suppressor gene, leads to abrogation of glycosaminoglycan (GAG) biosynthesis. This impairs distribution and signaling activities of various morphogens such as Hedgehog (Hh), Wingless (Wg), and Decapentaplegic (Dpp). Mutations in members of the exostosin (EXT) gene family lead to hereditary multiple exostosis in humans leading to bone outgrowths and tumors. In this study, we provide genetic and biochemical evidence that the human EXT1 (hEXT1) gene is conserved through species and can functionally complement the ttv mutation in Drosophila. The hEXT1 gene was able to rescue a ttv null mutant to adulthood and restore GAG biosynthesis.
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Evidence for complete epistasis of null mutations in murine Fanconi anemia genes Fanca and Fancg.
van de Vrugt, Henri J; Koomen, Mireille; Bakker, Sietske; Berns, Mariska A D; Cheng, Ngan Ching; van der Valk, Martin A; de Vries, Yne; Rooimans, Martin A; Oostra, Anneke B; Hoatlin, Maureen E; Te Riele, Hein; Joenje, Hans; Arwert, Fré
2011-12-10
Fanconi anemia (FA) is a heritable disease characterized by bone marrow failure, congenital abnormalities, and cancer predisposition. The 15 identified FA genes operate in a molecular pathway to preserve genomic integrity. Within this pathway the FA core complex operates as an ubiquitin ligase that activates the complex of FANCD2 and FANCI to coordinate DNA repair. The FA core complex is formed by at least 12 proteins. However, only the FANCL subunit displays ubiquitin ligase activity. FANCA and FANCG are members of the FA core complex for which no other functions have been described than to participate in protein interactions. In this study we generated mice with combined null alleles for Fanca and Fancg to identify extended functions for these genes by characterizing the double mutant mice and cells. Double mutant a(-/-)/g(-/-) mice were born at near Mendelian frequencies without apparent developmental abnormalities. Histological analysis of a(-/-)/g(-/-) mice revealed a Leydig cell hyperplasia and frequent vacuolization of Sertoli cells in testes, while ovaries were depleted from developing follicles and displayed an interstitial cell hyperplasia. These gonadal aberrations were associated with a compromised fertility of a(-/-)/g(-/-) males and females. During the first year of life a(-/-)/g(-/-) did not develop malignancies or bone marrow failure. At the cellular level a(-/-)/g(-/-), Fanca(-/-), and Fancg(-/-) cells proved equally compromised in DNA crosslink and homology-directed repair. Overall the phenotype of a(-/-)/g(-/-) double knockout mice and cells appeared highly similar to the phenotype of Fanca or Fancg single knockouts. The lack of an augmented phenotype suggest that null mutations in Fanca or Fancg are fully epistatic, making additional important functions outside of the FA core complex highly unlikely. 2011 Elsevier B.V. All rights reserved.
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Kirk, Joseph A.; Gebhart, Dana; Buckley, Anthony M.; Lok, Stephen; Scholl, Dean; Douce, Gillian R.; Govoni, Gregory R.; Fagan, Robert P.
2017-01-01
Avidocin-CDs are a new class of precision bactericidal agents that do not damage resident gut microbiota and are unlikely to promote the spread of antibiotic resistance. The precision killing properties result from the fusion of bacteriophage receptor binding proteins (RBPs) to a lethal contractile scaffold from an R-type bacteriocin. We recently described the prototypic Avidocin-CD, Av-CD291.2, that specifically kills C. difficile ribotype 027 strains and prevents colonization of mice. We have since selected two rare Av-CD291.2 resistant mutants of strain R20291 (RT027; S-layer cassette type-4, SCLT-4). These mutants have distinct point mutations in the slpA gene that result in an S-layer null phenotype. Reversion of the mutations to wild-type restored normal SLCT-4 S-layer formation and Av-CD291.2 sensitivity; however, complementation with other SCLT alleles did not restore Av-CD291.2 sensitivity despite restoring S-layer formation. Using newly identified phage RBPs, we constructed a panel of new Avidocin-CDs that kill C. difficile isolates in an SLCT-dependent manner, confirming the S-layer as the receptor in every case. In addition to bacteriophage adsorption, characterization of the S-layer null mutant also uncovered important roles for SlpA in sporulation, resistance to lysozyme and LL-37, and toxin production. Surprisingly, the S-layer-null mutant was found to persist in the hamster gut despite its completely attenuated virulence. Avidocin-CDs have significant therapeutic potential for the treatment and prevention of C. difficile Infection (CDI) given their exquisite specificity for the pathogen. Furthermore, the emergence of resistance forces mutants to trade virulence for continued viability and, therefore, greatly reduce their potential clinical impact. PMID:28878013
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Wang, Hong; Iguchi, Naoko; Rong, Qi; Zhou, Minliang; Ogunkorode, Martina; Inoue, Masashi; Pribitkin, Edmund A; Bachmanov, Alexander A; Margolskee, Robert F; Pfeifer, Karl; Huang, Liquan
2009-01-20
Vertebrate taste buds undergo continual cell turnover. To understand how the gustatory progenitor cells in the stratified lingual epithelium migrate and differentiate into different types of mature taste cells, we sought to identify genes that were selectively expressed in taste cells at different maturation stages. Here we report the expression of the voltage-gated potassium channel KCNQ1 in mammalian taste buds of mouse, rat, and human. Immunohistochemistry and nuclear staining showed that nearly all rodent and human taste cells express this channel. Double immunostaining with antibodies against type II and III taste cell markers validated the presence of KCNQ1 in these two types of cells. Co-localization studies with cytokeratin 14 indicated that KCNQ1 is also expressed in type IV basal precursor cells. Null mutation of the kcnq1 gene in mouse, however, did not alter the gross structure of taste buds or the expression of taste signaling molecules. Behavioral assays showed that the mutant mice display reduced preference to some umami substances, but not to any other taste compounds tested. Gustatory nerve recordings, however, were unable to detect any significant change in the integrated nerve responses of the mutant mice to umami stimuli. These results suggest that although it is expressed in nearly all taste bud cells, the function of KCNQ1 is not required for gross taste bud development or peripheral taste transduction pathways, and the reduced preference of kcnq1-null mice in the behavioral assays may be attributable to the deficiency in the central nervous system or other organs.
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O'Rourke, Thomas W; Doudican, Nicole A; Mackereth, Melinda D; Doetsch, Paul W; Shadel, Gerald S
2002-06-01
The mitochondrial genome is a significant target of exogenous and endogenous genotoxic agents; however, the determinants that govern this susceptibility and the pathways available to resist mitochondrial DNA (mtDNA) damage are not well characterized. Here we report that oxidative mtDNA damage is elevated in strains lacking Ntg1p, providing the first direct functional evidence that this mitochondrion-localized, base excision repair enzyme functions to protect mtDNA. However, ntg1 null strains did not exhibit a mitochondrial respiration-deficient (petite) phenotype, suggesting that mtDNA damage is negotiated by the cooperative actions of multiple damage resistance pathways. Null mutations in ABF2 or PIF1, two genes implicated in mtDNA maintenance and recombination, exhibit a synthetic-petite phenotype in combination with ntg1 null mutations that is accompanied by enhanced mtDNA point mutagenesis in the corresponding double-mutant strains. This phenotype was partially rescued by malonic acid, indicating that reactive oxygen species generated by the electron transport chain contribute to mitochondrial dysfunction in abf2 Delta strains. In contrast, when two other genes involved in mtDNA recombination, CCE1 and NUC1, were inactivated a strong synthetic-petite phenotype was not observed, suggesting that the effects mediated by Abf2p and Pif1p are due to novel activities of these proteins other than recombination. These results document the existence of recombination-independent mechanisms in addition to base excision repair to cope with oxidative mtDNA damage in Saccharomyces cerevisiae. Such systems are likely relevant to those operating in human cells where mtDNA recombination is less prevalent, validating yeast as a model system in which to study these important issues.
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Fast randomization of large genomic datasets while preserving alteration counts.
Gobbi, Andrea; Iorio, Francesco; Dawson, Kevin J; Wedge, David C; Tamborero, David; Alexandrov, Ludmil B; Lopez-Bigas, Nuria; Garnett, Mathew J; Jurman, Giuseppe; Saez-Rodriguez, Julio
2014-09-01
Studying combinatorial patterns in cancer genomic datasets has recently emerged as a tool for identifying novel cancer driver networks. Approaches have been devised to quantify, for example, the tendency of a set of genes to be mutated in a 'mutually exclusive' manner. The significance of the proposed metrics is usually evaluated by computing P-values under appropriate null models. To this end, a Monte Carlo method (the switching-algorithm) is used to sample simulated datasets under a null model that preserves patient- and gene-wise mutation rates. In this method, a genomic dataset is represented as a bipartite network, to which Markov chain updates (switching-steps) are applied. These steps modify the network topology, and a minimal number of them must be executed to draw simulated datasets independently under the null model. This number has previously been deducted empirically to be a linear function of the total number of variants, making this process computationally expensive. We present a novel approximate lower bound for the number of switching-steps, derived analytically. Additionally, we have developed the R package BiRewire, including new efficient implementations of the switching-algorithm. We illustrate the performances of BiRewire by applying it to large real cancer genomics datasets. We report vast reductions in time requirement, with respect to existing implementations/bounds and equivalent P-value computations. Thus, we propose BiRewire to study statistical properties in genomic datasets, and other data that can be modeled as bipartite networks. BiRewire is available on BioConductor at http://www.bioconductor.org/packages/2.13/bioc/html/BiRewire.html. Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press.
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Schaetzlein, Sonja; Chahwan, Richard; Avdievich, Elena; Roa, Sergio; Wei, Kaichun; Eoff, Robert L.; Sellers, Rani S.; Clark, Alan B.; Kunkel, Thomas A.; Scharff, Matthew D.; Edelmann, Winfried
2013-01-01
Mammalian Exonuclease 1 (EXO1) is an evolutionarily conserved, multifunctional exonuclease involved in DNA damage repair, replication, immunoglobulin diversity, meiosis, and telomere maintenance. It has been assumed that EXO1 participates in these processes primarily through its exonuclease activity, but recent studies also suggest that EXO1 has a structural function in the assembly of higher-order protein complexes. To dissect the enzymatic and nonenzymatic roles of EXO1 in the different biological processes in vivo, we generated an EXO1-E109K knockin (Exo1EK) mouse expressing a stable exonuclease-deficient protein and, for comparison, a fully EXO1-deficient (Exo1null) mouse. In contrast to Exo1null/null mice, Exo1EK/EK mice retained mismatch repair activity and displayed normal class switch recombination and meiosis. However, both Exo1-mutant lines showed defects in DNA damage response including DNA double-strand break repair (DSBR) through DNA end resection, chromosomal stability, and tumor suppression, indicating that the enzymatic function is required for those processes. On a transformation-related protein 53 (Trp53)-null background, the DSBR defect caused by the E109K mutation altered the tumor spectrum but did not affect the overall survival as compared with p53-Exo1null mice, whose defects in both DSBR and mismatch repair also compromised survival. The separation of these functions demonstrates the differential requirement for the structural function and nuclease activity of mammalian EXO1 in distinct DNA repair processes and tumorigenesis in vivo. PMID:23754438
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Correction of the sickle cell disease mutation in human hematopoietic stem/progenitor cells.
Hoban, Megan D; Cost, Gregory J; Mendel, Matthew C; Romero, Zulema; Kaufman, Michael L; Joglekar, Alok V; Ho, Michelle; Lumaquin, Dianne; Gray, David; Lill, Georgia R; Cooper, Aaron R; Urbinati, Fabrizia; Senadheera, Shantha; Zhu, Allen; Liu, Pei-Qi; Paschon, David E; Zhang, Lei; Rebar, Edward J; Wilber, Andrew; Wang, Xiaoyan; Gregory, Philip D; Holmes, Michael C; Reik, Andreas; Hollis, Roger P; Kohn, Donald B
2015-04-23
Sickle cell disease (SCD) is characterized by a single point mutation in the seventh codon of the β-globin gene. Site-specific correction of the sickle mutation in hematopoietic stem cells would allow for permanent production of normal red blood cells. Using zinc-finger nucleases (ZFNs) designed to flank the sickle mutation, we demonstrate efficient targeted cleavage at the β-globin locus with minimal off-target modification. By co-delivering a homologous donor template (either an integrase-defective lentiviral vector or a DNA oligonucleotide), high levels of gene modification were achieved in CD34(+) hematopoietic stem and progenitor cells. Modified cells maintained their ability to engraft NOD/SCID/IL2rγ(null) mice and to produce cells from multiple lineages, although with a reduction in the modification levels relative to the in vitro samples. Importantly, ZFN-driven gene correction in CD34(+) cells from the bone marrow of patients with SCD resulted in the production of wild-type hemoglobin tetramers. © 2015 by The American Society of Hematology.
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A de novo mutation in KIT causes white spotting in a subpopulation of German Shepherd dogs.
Wong, A K; Ruhe, A L; Robertson, K R; Loew, E R; Williams, D C; Neff, M W
2013-06-01
Although variation in the KIT gene is a common cause of white spotting among domesticated animals, KIT has not been implicated in the diverse white spotting observed in the dog. Here, we show that a loss-of-function mutation in KIT recapitulates the coat color phenotypes observed in other species. A spontaneous white spotting observed in a pedigree of German Shepherd dogs was mapped by linkage analysis to a single locus on CFA13 containing KIT (pairwise LOD = 15). DNA sequence analysis identified a novel 1-bp insertion in the second exon that co-segregated with the phenotype. The expected frameshift and resulting premature stop codons predicted a severely truncated c-Kit receptor with presumably abolished activity. No dogs homozygous for the mutation were recovered from multiple intercrosses (P = 0.01), suggesting the mutation is recessively embryonic lethal. These observations are consistent with the effects of null alleles of KIT in other species. © 2012 The Authors, Animal Genetics © 2012 Stichting International Foundation for Animal Genetics.
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Yamamoto, Kenta; Wang, Jiguang; Sprinzen, Lisa; Xu, Jun; Haddock, Christopher J; Li, Chen; Lee, Brian J; Loredan, Denis G; Jiang, Wenxia; Vindigni, Alessandro; Wang, Dong; Rabadan, Raul; Zha, Shan
2016-06-15
Missense mutations in ATM kinase, a master regulator of DNA damage responses, are found in many cancers, but their impact on ATM function and implications for cancer therapy are largely unknown. Here we report that 72% of cancer-associated ATM mutations are missense mutations that are enriched around the kinase domain. Expression of kinase-dead ATM (Atm(KD/-)) is more oncogenic than loss of ATM (Atm(-/-)) in mouse models, leading to earlier and more frequent lymphomas with Pten deletions. Kinase-dead ATM protein (Atm-KD), but not loss of ATM (Atm-null), prevents replication-dependent removal of Topo-isomerase I-DNA adducts at the step of strand cleavage, leading to severe genomic instability and hypersensitivity to Topo-isomerase I inhibitors. Correspondingly, Topo-isomerase I inhibitors effectively and preferentially eliminate Atm(KD/-), but not Atm-proficientor Atm(-/-) leukemia in animal models. These findings identify ATM kinase-domain missense mutations as a potent oncogenic event and a biomarker for Topo-isomerase I inhibitor based therapy.
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Ameloblast Modulation and Transport of Cl−, Na+, and K+ during Amelogenesis
Bronckers, A.L.J.J.; Lyaruu, D.; Jalali, R.; Medina, J.F.; Zandieh-Doulabi, B.; DenBesten, P.K.
2015-01-01
Ameloblasts express transmembrane proteins for transport of mineral ions and regulation of pH in the enamel space. Two major transporters recently identified in ameloblasts are the Na+K+-dependent calcium transporter NCKX4 and the Na+-dependent HPO42– (Pi) cotransporter NaPi-2b. To regulate pH, ameloblasts express anion exchanger 2 (Ae2a,b), chloride channel Cftr, and amelogenins that can bind protons. Exposure to fluoride or null mutation of Cftr, Ae2a,b, or Amelx each results in formation of hypomineralized enamel. We hypothesized that enamel hypomineralization associated with disturbed pH regulation results from reduced ion transport by NCKX4 and NaPi-2b. This was tested by correlation analyses among the levels of Ca, Pi, Cl, Na, and K in forming enamel of mice with null mutation of Cftr, Ae2a,b, and Amelx, according to quantitative x-ray electron probe microanalysis. Immunohistochemistry, polymerase chain reaction analysis, and Western blotting confirmed the presence of apical NaPi-2b and Nckx4 in maturation-stage ameloblasts. In wild-type mice, K levels in enamel were negatively correlated with Ca and Cl but less negatively or even positively in fluorotic enamel. Na did not correlate with P or Ca in enamel of wild-type mice but showed strong positive correlation in fluorotic and nonfluorotic Ae2a,b- and Cftr-null enamel. In hypomineralizing enamel of all models tested, 1) Cl− was strongly reduced; 2) K+ and Na+ accumulated (Na+ not in Amelx-null enamel); and 3) modulation was delayed or blocked. These results suggest that a Na+K+-dependent calcium transporter (likely NCKX4) and a Na+-dependent Pi transporter (potentially NaPi-2b) located in ruffle-ended ameloblasts operate in a coordinated way with the pH-regulating machinery to transport Ca2+, Pi, and bicarbonate into maturation-stage enamel. Acidification and/or associated physicochemical/electrochemical changes in ion levels in enamel fluid near the apical ameloblast membrane may reduce the transport activity of mineral transporters, which results in hypomineralization. PMID:26403673
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Brachvogel, Bent; Zaucke, Frank; Dave, Keyur; Norris, Emma L.; Stermann, Jacek; Dayakli, Münire; Koch, Manuel; Gorman, Jeffrey J.; Bateman, John F.; Wilson, Richard
2013-01-01
The cartilage extracellular matrix is essential for endochondral bone development and joint function. In addition to the major aggrecan/collagen II framework, the interacting complex of collagen IX, matrilin-3, and cartilage oligomeric matrix protein (COMP) is essential for cartilage matrix stability, as mutations in Col9a1, Col9a2, Col9a3, Comp, and Matn3 genes cause multiple epiphyseal dysplasia, in which patients develop early onset osteoarthritis. In mice, collagen IX ablation results in severely disturbed growth plate organization, hypocellular regions, and abnormal chondrocyte shape. This abnormal differentiation is likely to involve altered cell-matrix interactions but the mechanism is not known. To investigate the molecular basis of the collagen IX null phenotype we analyzed global differences in protein abundance between wild-type and knock-out femoral head cartilage by capillary HPLC tandem mass spectrometry. We identified 297 proteins in 3-day cartilage and 397 proteins in 21-day cartilage. Components that were differentially abundant between wild-type and collagen IX-deficient cartilage included 15 extracellular matrix proteins. Collagen IX ablation was associated with dramatically reduced COMP and matrilin-3, consistent with known interactions. Matrilin-1, matrilin-4, epiphycan, and thrombospondin-4 levels were reduced in collagen IX null cartilage, providing the first in vivo evidence for these proteins belonging to the collagen IX interactome. Thrombospondin-4 expression was reduced at the mRNA level, whereas matrilin-4 was verified as a novel collagen IX-binding protein. Furthermore, changes in TGFβ-induced protein βig-h3 and fibronectin abundance were found in the collagen IX knock-out but not associated with COMP ablation, indicating specific involvement in the abnormal collagen IX null cartilage. In addition, the more widespread expression of collagen XII in the collagen IX-deficient cartilage suggests an attempted compensatory response to the absence of collagen IX. Our differential proteomic analysis of cartilage is a novel approach to identify candidate matrix protein interactions in vivo, underpinning further analysis of mutant cartilage lacking other matrix components or harboring disease-causing mutations. PMID:23530037
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Ameloblast Modulation and Transport of Cl⁻, Na⁺, and K⁺ during Amelogenesis.
Bronckers, A L J J; Lyaruu, D; Jalali, R; Medina, J F; Zandieh-Doulabi, B; DenBesten, P K
2015-12-01
Ameloblasts express transmembrane proteins for transport of mineral ions and regulation of pH in the enamel space. Two major transporters recently identified in ameloblasts are the Na(+)K(+)-dependent calcium transporter NCKX4 and the Na(+)-dependent HPO4 (2-) (Pi) cotransporter NaPi-2b. To regulate pH, ameloblasts express anion exchanger 2 (Ae2a,b), chloride channel Cftr, and amelogenins that can bind protons. Exposure to fluoride or null mutation of Cftr, Ae2a,b, or Amelx each results in formation of hypomineralized enamel. We hypothesized that enamel hypomineralization associated with disturbed pH regulation results from reduced ion transport by NCKX4 and NaPi-2b. This was tested by correlation analyses among the levels of Ca, Pi, Cl, Na, and K in forming enamel of mice with null mutation of Cftr, Ae2a,b, and Amelx, according to quantitative x-ray electron probe microanalysis. Immunohistochemistry, polymerase chain reaction analysis, and Western blotting confirmed the presence of apical NaPi-2b and Nckx4 in maturation-stage ameloblasts. In wild-type mice, K levels in enamel were negatively correlated with Ca and Cl but less negatively or even positively in fluorotic enamel. Na did not correlate with P or Ca in enamel of wild-type mice but showed strong positive correlation in fluorotic and nonfluorotic Ae2a,b- and Cftr-null enamel. In hypomineralizing enamel of all models tested, 1) Cl(-) was strongly reduced; 2) K(+) and Na(+) accumulated (Na(+) not in Amelx-null enamel); and 3) modulation was delayed or blocked. These results suggest that a Na(+)K(+)-dependent calcium transporter (likely NCKX4) and a Na(+)-dependent Pi transporter (potentially NaPi-2b) located in ruffle-ended ameloblasts operate in a coordinated way with the pH-regulating machinery to transport Ca(2+), Pi, and bicarbonate into maturation-stage enamel. Acidification and/or associated physicochemical/electrochemical changes in ion levels in enamel fluid near the apical ameloblast membrane may reduce the transport activity of mineral transporters, which results in hypomineralization. © International & American Associations for Dental Research 2015.
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Dutta, A. K.; Paulose, B. K.; Danda, S.; Alexander, S.; Tamilarasi, V.; Omprakash, S.
2016-01-01
Primary hyperoxaluria type 1 is an autosomal recessive inborn error of metabolism due to liver-specific peroxisomal enzyme alanine-glyoxylate transaminase deficiency. Here, we describe two unrelated patients who were diagnosed to have primary hyperoxaluria. Homozygous c.445_452delGTGCTGCT (p.L151Nfs*14) (Transcript ID: ENST00000307503; human genome assembly GRCh38.p2) (HGMD ID CD073567) mutation was detected in both the patients and the parents were found to be heterozygous carriers. Our patients developed end-stage renal disease at 23 years and 35 years of age. However, in the largest series published from OxalEurope cohort, the median age of end-stage renal disease for null mutations carriers was 9.9 years, which is much earlier than our cases. Our patients had slower progressions as compared to three unrelated patients from North India and Pakistan, who had homozygous c.302T>C (p.L101P) (HGMD ID CM093792) mutation in exon 2. Further, patients need to be studied to find out if c.445_452delGTGCTGCT mutation represents a founder mutation in Southern India. PMID:27512303
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Shroyer, N F; Lewis, R A; Yatsenko, A N; Wensel, T G; Lupski, J R
2001-11-01
Mutations in ABCR (ABCA4) have been reported to cause a spectrum of autosomal recessively inherited retinopathies, including Stargardt disease (STGD), cone-rod dystrophy and retinitis pigmentosa. Individuals heterozygous for ABCR mutations may be predisposed to develop the multifactorial disorder age-related macular degeneration (AMD). We hypothesized that some carriers of STGD alleles have an increased risk to develop AMD. We tested this hypothesis in a cohort of families that manifest both STGD and AMD. With a direct-sequencing mutation detection strategy, we found that AMD-affected relatives of STGD patients are more likely to be carriers of pathogenic STGD alleles than predicted based on chance alone. We further investigated the role of AMD-associated ABCR mutations by testing for expression and ATP-binding defects in an in vitro biochemical assay. We found that mutations associated with AMD have a range of assayable defects ranging from no detectable defect to apparent null alleles. Of the 21 missense ABCR mutations reported in patients with AMD, 16 (76%) show abnormalities in protein expression, ATP-binding or ATPase activity. We infer that carrier relatives of STGD patients are predisposed to develop AMD.
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J domain independent functions of J proteins.
Ajit Tamadaddi, Chetana; Sahi, Chandan
2016-07-01
Heat shock proteins of 40 kDa (Hsp40s), also called J proteins, are obligate partners of Hsp70s. Via their highly conserved and functionally critical J domain, J proteins interact and modulate the activity of their Hsp70 partners. Mutations in the critical residues in the J domain often result in the null phenotype for the J protein in question. However, as more J proteins have been characterized, it is becoming increasingly clear that a significant number of J proteins do not "completely" rely on their J domains to carry out their cellular functions, as previously thought. In some cases, regions outside the highly conserved J domain have become more important making the J domain dispensable for some, if not for all functions of a J protein. This has profound effects on the evolution of such J proteins. Here we present selected examples of J proteins that perform J domain independent functions and discuss this in the context of evolution of J proteins with dispensable J domains and J-like proteins in eukaryotes.
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Interferon-induced TRAIL-independent cell death in DNase II-/- embryos.
Kitahara, Yusuke; Kawane, Kohki; Nagata, Shigekazu
2010-09-01
The chromosomal DNA of apoptotic cells and the nuclear DNA expelled from erythroid precursors is cleaved by DNase II in lysosomes after the cells or nuclei are engulfed by macrophages. DNase II(-/-) embryos suffer from lethal anemia due to IFN-beta produced in the macrophages carrying undigested DNA. Here, we show that Type I IFN induced a caspase-dependent cell death in human epithelial cells that were transformed to express a high level of IFN type I receptor. During this death process, a set of genes was strongly activated, one of which encoded TRAIL, a death ligand. A high level of TRAIL mRNA was also found in the fetal liver of the lethally anemic DNase II(-/-) embryos, and a lack of IFN type I receptor in the DNase II(-/-) IFN-IR(-/-) embryos blocked the expression of TRAIL mRNA. However, a null mutation in TRAIL did not rescue the lethal anemia of the DNase II(-/-) embryos, indicating that TRAIL is dispensable for inducing the apoptosis of erythroid cells in DNase II(-/-) embryos, and therefore, that there is a TRAIL-independent mechanism for the IFN-induced apoptosis.
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Handschuh, Karen; Feenstra, Jennifer; Koss, Matthew; Ferretti, Elisabetta; Risolino, Maurizio; Zewdu, Rediet; Sahai, Michelle A; Bénazet, Jean-Denis; Peng, Xiao P; Depew, Michael J; Quintana, Laura; Sharpe, James; Wang, Baolin; Alcorn, Heather; Rivi, Roberta; Butcher, Stephen; Manak, J Robert; Vaccari, Thomas; Weinstein, Harel; Anderson, Kathryn V; Lacy, Elizabeth; Selleri, Licia
2014-10-23
Sorting and degradation of receptors and associated signaling molecules maintain homeostasis of conserved signaling pathways during cell specification and tissue development. Yet, whether machineries that sort signaling proteins act preferentially on different receptors and ligands in different contexts remains mysterious. Here, we show that Vacuolar protein sorting 25, Vps25, a component of ESCRT-II (Endosomal Sorting Complex Required for Transport II), directs preferential endosome-mediated modulation of FGF signaling in limbs. By ENU-induced mutagenesis, we isolated a polydactylous mouse line carrying a hypomorphic mutation of Vps25 (Vps25(ENU)). Unlike Vps25-null embryos we generated, Vps25(ENU/ENU) mutants survive until late gestation. Their limbs display FGF signaling enhancement and consequent hyperactivation of the FGF-SHH feedback loop causing polydactyly, whereas WNT and BMP signaling remain unperturbed. Notably, Vps25(ENU/ENU) Mouse Embryonic Fibroblasts exhibit aberrant FGFR trafficking and degradation; however, SHH signaling is unperturbed. These studies establish that the ESCRT-II machinery selectively limits FGF signaling in vertebrate skeletal patterning.
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Lee, Gyunghee; Wang, Zixing; Sehgal, Ritika; Chen, Chun-Hong; Kikuno, Keiko; Hay, Bruce; Park, Jae H
2011-01-01
A great number of obsolete larval neurons in the Drosophila central nervous system are eliminated by developmentally programmed cell death (PCD) during early metamorphosis. To elucidate the mechanisms of neuronal PCD occurring during this period, we undertook genetic dissection of seven currently known Drosophila caspases in the PCD of a group of interneurons (vCrz) that produce corazonin (Crz) neuropeptide in the ventral nerve cord. The molecular death program in the vCrz neurons initiates within 1 hour after pupariation, as demonstrated by the cytological signs of cell death and caspase activation. PCD was significantly suppressed in dronc-null mutants, but not in null mutants of either dredd or strica. A double mutation lacking both dronc and strica impaired PCD phenotype more severely than did a dronc mutation alone, but comparably to a triple dredd/strica/dronc mutation, indicating that dronc is a main initiator caspase, while strica plays a minor role that overlaps with dronc's. As for effector caspases, vCrz PCD requires both ice and dcp-1 functions, as they work cooperatively for a timely removal of the vCrz neurons. Interestingly, the activation of the Ice and Dcp-1 is not solely dependent on Dronc and Strica, implying an alternative pathway to activate the effectors. Two remaining effector caspase genes, decay and damm, found no apparent functions in the neuronal PCD, at least during early metamorphosis. Overall, our work revealed that vCrz PCD utilizes dronc, strica, dcp-1, and ice wherein the activation of Ice and Dcp-1 requires a novel pathway in addition to the initiator caspases.
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Large deletion in PIGL: a common mutational mechanism in CHIME syndrome?
Ceroni, José Rm; Yamamoto, Guilherme L; Honjo, Rachel S; Kim, Chong A; Passos-Bueno, Maria R; Bertola, Débora R
2018-01-01
CHIME syndrome is an extremely rare autosomal recessive multisystemic disorder caused by mutations in PIGL. PIGL is an endoplasmic reticulum localized enzyme that catalyzes the second step of glycosylphosphatidylinositol (GPI) biosynthesis, which plays a role in the anchorage of cell-surface proteins including receptors, enzymes, and adhesion molecules. Germline mutations in other members of GPI and Post GPI Attachment to Proteins (PGAP) family genes have been described and constitute a group of diseases within the congenital disorders of glycosylation. Patients in this group often present alkaline phosphatase serum levels abnormalities and neurological symptoms. We report a CHIME syndrome patient who harbors a missense mutation c.500T > C (p.Leu167Pro) and a large deletion involving the 5' untranslated region and part of exon 1 of PIGL. In CHIME syndrome, a recurrent missense mutation c.500T > C (p.Leu167Pro) is found in the majority of patients, associated with a null mutation in the other allele, including an overrepresentation of large deletions. The latter are not detected by the standard analysis in sequencing techniques, including next-generation sequencing. Thus, in individuals with a clinical diagnosis of CHIME syndrome in which only one mutation is found, an active search for a large deletion should be sought.
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Large deletion in PIGL: a common mutational mechanism in CHIME syndrome?
Ceroni, José RM; Yamamoto, Guilherme L; Honjo, Rachel S; Kim, Chong A; Passos-Bueno, Maria R; Bertola, Débora R
2018-01-01
Abstract CHIME syndrome is an extremely rare autosomal recessive multisystemic disorder caused by mutations in PIGL. PIGL is an endoplasmic reticulum localized enzyme that catalyzes the second step of glycosylphosphatidylinositol (GPI) biosynthesis, which plays a role in the anchorage of cell-surface proteins including receptors, enzymes, and adhesion molecules. Germline mutations in other members of GPI and Post GPI Attachment to Proteins (PGAP) family genes have been described and constitute a group of diseases within the congenital disorders of glycosylation. Patients in this group often present alkaline phosphatase serum levels abnormalities and neurological symptoms. We report a CHIME syndrome patient who harbors a missense mutation c.500T > C (p.Leu167Pro) and a large deletion involving the 5’ untranslated region and part of exon 1 of PIGL. In CHIME syndrome, a recurrent missense mutation c.500T > C (p.Leu167Pro) is found in the majority of patients, associated with a null mutation in the other allele, including an overrepresentation of large deletions. The latter are not detected by the standard analysis in sequencing techniques, including next-generation sequencing. Thus, in individuals with a clinical diagnosis of CHIME syndrome in which only one mutation is found, an active search for a large deletion should be sought. PMID:29473937
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Universality in a Neutral Evolution Model
NASA Astrophysics Data System (ADS)
King, Dawn; Scott, Adam; Maric, Nevena; Bahar, Sonya
2013-03-01
Agent-based models are ideal for investigating the complex problems of biodiversity and speciation because they allow for complex interactions between individuals and between individuals and the environment. Presented here is a ``null'' model that investigates three mating types - assortative, bacterial, and random - in phenotype space, as a function of the percentage of random death δ. Previous work has shown phase transition behavior in an assortative mating model with variable fitness landscapes as the maximum mutation size (μ) was varied (Dees and Bahar, 2010). Similarly, this behavior was recently presented in the work of Scott et al. (submitted), on a completely neutral landscape, for bacterial-like fission as well as for assortative mating. Here, in order to achieve an appropriate ``null'' hypothesis, the random death process was changed so each individual, in each generation, has the same probability of death. Results show a continuous nonequilibrium phase transition for the order parameters of the population size and the number of clusters (analogue of species) as δ is varied for three different mutation sizes of the system. The system shows increasing robustness as μ increases. Universality classes and percolation properties of this system are also explored. This research was supported by funding from: University of Missouri Research Board and James S. McDonnell Foundation
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Impaired clock output by altered connectivity in the circadian network.
Fernández, María de la Paz; Chu, Jessie; Villella, Adriana; Atkinson, Nigel; Kay, Steve A; Ceriani, María Fernanda
2007-03-27
Substantial progress has been made in elucidating the molecular processes that impart a temporal control to physiology and behavior in most eukaryotes. In Drosophila, dorsal and ventral neuronal networks act in concert to convey rhythmicity. Recently, the hierarchical organization among the different circadian clusters has been addressed, but how molecular oscillations translate into rhythmic behavior remains unclear. The small ventral lateral neurons can synchronize certain dorsal oscillators likely through the release of pigment dispersing factor (PDF), a neuropeptide central to the control of rhythmic rest-activity cycles. In the present study, we have taken advantage of flies exhibiting a distinctive arrhythmic phenotype due to mutation of the potassium channel slowpoke (slo) to examine the relevance of specific neuronal populations involved in the circadian control of behavior. We show that altered neuronal function associated with the null mutation specifically impaired PDF accumulation in the dorsal protocerebrum and, in turn, desynchronized molecular oscillations in the dorsal clusters. However, molecular oscillations in the small ventral lateral neurons are properly running in the null mutant, indicating that slo is acting downstream of these core pacemaker cells, most likely in the output pathway. Surprisingly, disrupted PDF signaling by slo dysfunction directly affects the structure of the underlying circuit. Our observations demonstrate that subtle structural changes within the circadian network are responsible for behavioral arrhythmicity.
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Gao, Yu; Gartenhaus, Ronald B.; Lapidus, Rena G.; Hussain, Arif; Zhang, Yanting; Wang, Xinghuan; Dan, Han C.
2015-01-01
The serine/threonine protein kinase Akt plays a critical role in regulating proliferation, growth and survival through phosphorylation of different downstream substrates. The mammalian target of rapamycin (mTOR) is a key target for Akt to promote tumorigenesis. It has been reported that Akt activates mTOR through phosphorylation and inhibition of the tuberous sclerosis complex (TSC) protein TSC2. Previously it was demonstrated that mTOR activates IKK/NF-κB signaling by promoting IKK activity downstream of Akt in conditions deficient of PTEN. In the current study, the mechanistic role of the tumor suppressor TSC2 was investigated in the regulation of IKK/NF-κB activity in PTEN-null prostate cancer and in TSC2 mutated tumor cells. The results demonstrate that TSC2 inhibits IKK/NF-κB activity downstream of Akt and upstream of mTORC1 in a PTEN deficient environment. However, TSC2 promotes IKK/NF-κB activity upstream of Akt and mTORC1 in TSC2 mutated tumor cells. These data indicate that TSC2 negatively or positively regulates IKK/NF-κB activity in a context-dependent manner depending on the genetic background. PMID:26374334
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Whistler mode refraction in highly nonuniform magnetic fields
NASA Astrophysics Data System (ADS)
Urrutia, J. M.; Stenzel, R.
2016-12-01
In a large laboratory plasma the propagation of whistler modes is measured in highly nonuniform magnetic fields created by a current-carrying wires. Ray tracing is not applicable since the wavelength and gradient scale length are comparable. The waves are excited with a loop antenna near the wire. The antenna launches an m=1 helicon mode in a uniform plasma. The total magnetic field consists of a weak uniform background field and a nearly circular field of a straight wire across the background field. A circular loop produces 3D null points and a 2D null line. The whistler wave propagation will be shown. It is relevant to whistler mode propagation in space plasmas near magnetic null-points, small flux ropes, lunar crustal magnetic fields and active wave injection experiments.
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Woods, C G; Stricker, S; Seemann, P; Stern, R; Cox, J; Sherridan, E; Roberts, E; Springell, K; Scott, S; Karbani, G; Sharif, S M; Toomes, C; Bond, J; Kumar, D; Al-Gazali, L; Mundlos, S
2006-08-01
Fuhrmann syndrome and the Al-Awadi/Raas-Rothschild/Schinzel phocomelia syndrome are considered to be distinct limb-malformation disorders characterized by various degrees of limb aplasia/hypoplasia and joint dysplasia in humans. In families with these syndromes, we found homozygous missense mutations in the dorsoventral-patterning gene WNT7A and confirmed their functional significance in retroviral-mediated transfection of chicken mesenchyme cell cultures and developing limbs. The results suggest that a partial loss of WNT7A function causes Fuhrmann syndrome (and a phenotype similar to mouse Wnt7a knockout), whereas the more-severe limb truncation phenotypes observed in Al-Awadi/Raas-Rothschild/Schinzel phocomelia syndrome result from null mutations (and cause a phenotype similar to mouse Shh knockout). These findings illustrate the specific and conserved importance of WNT7A in multiple aspects of vertebrate limb development.
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Woods, C. G.; Stricker, S.; Seemann, P.; Stern, R.; Cox, J.; Sherridan, E.; Roberts, E.; Springell, K.; Scott, S.; Karbani, G.; Sharif, S. M.; Toomes, C.; Bond, J.; Kumar, D.; Al-Gazali, L.; Mundlos, S.
2006-01-01
Fuhrmann syndrome and the Al-Awadi/Raas-Rothschild/Schinzel phocomelia syndrome are considered to be distinct limb-malformation disorders characterized by various degrees of limb aplasia/hypoplasia and joint dysplasia in humans. In families with these syndromes, we found homozygous missense mutations in the dorsoventral-patterning gene WNT7A and confirmed their functional significance in retroviral-mediated transfection of chicken mesenchyme cell cultures and developing limbs. The results suggest that a partial loss of WNT7A function causes Fuhrmann syndrome (and a phenotype similar to mouse Wnt7a knockout), whereas the more-severe limb truncation phenotypes observed in Al-Awadi/Raas-Rothschild/Schinzel phocomelia syndrome result from null mutations (and cause a phenotype similar to mouse Shh knockout). These findings illustrate the specific and conserved importance of WNT7A in multiple aspects of vertebrate limb development. PMID:16826533
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The DNA mismatch repair genes Msh3 and Msh6 cooperate in intestinal tumor suppression.
Edelmann, W; Umar, A; Yang, K; Heyer, J; Kucherlapati, M; Lia, M; Kneitz, B; Avdievich, E; Fan, K; Wong, E; Crouse, G; Kunkel, T; Lipkin, M; Kolodner, R D; Kucherlapati, R
2000-02-15
Repair of mismatches in DNA in mammalian cells is mediated by a complex of proteins that are members of two highly conserved families of genes referred to as MutS and MutL homologues. Germline mutations in several members of these families, MSH2, MSH6, MLH1, and PMS2, but not MSH3, are responsible for hereditary non-polyposis colorectal cancer. To examine the role of MSH3, we generated a mouse with a null mutation in this gene. Cells from Msh3-/- mice are defective in repair of insertion/ deletion mismatches but can repair base-base mismatches. Msh3-/- mice develop tumors at a late age. When the Msh3-/- and Msh6-/- mutations are combined, the tumor predisposition phenotype is indistinguishable from Msh2-/- or Mlh1-/- mice. These results suggest that MSH3 cooperates with MSH6 in tumor suppression.
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Hayes, Sidney; Rajamanickam, Karthic; Hayes, Connie
2018-04-05
λ genes O and P are required for replication initiation from the bacteriophage λ origin site, ori λ, located within gene O . Questions have persisted for years about whether O-defects can indeed be complemented in trans . We show the effect of original null mutations in O and the influence of four origin mutations (three are in-frame deletions and one is a point mutation) on complementation. This is the first demonstration that O proteins with internal deletions can complement for O activity, and that expression of the N-terminal portion of gene P can completely prevent O complementation. We show that O-P co-expression can limit the lethal effect of P on cell growth. We explore the influence of the contiguous small RNA OOP on O complementation and P-lethality.
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Brachvogel, Bent; Zaucke, Frank; Dave, Keyur; Norris, Emma L; Stermann, Jacek; Dayakli, Münire; Koch, Manuel; Gorman, Jeffrey J; Bateman, John F; Wilson, Richard
2013-05-10
Collagen IX is an integral cartilage extracellular matrix component important in skeletal development and joint function. Proteomic analysis and validation studies revealed novel alterations in collagen IX null cartilage. Matrilin-4, collagen XII, thrombospondin-4, fibronectin, βig-h3, and epiphycan are components of the in vivo collagen IX interactome. We applied a proteomics approach to advance our understanding of collagen IX ablation in cartilage. The cartilage extracellular matrix is essential for endochondral bone development and joint function. In addition to the major aggrecan/collagen II framework, the interacting complex of collagen IX, matrilin-3, and cartilage oligomeric matrix protein (COMP) is essential for cartilage matrix stability, as mutations in Col9a1, Col9a2, Col9a3, Comp, and Matn3 genes cause multiple epiphyseal dysplasia, in which patients develop early onset osteoarthritis. In mice, collagen IX ablation results in severely disturbed growth plate organization, hypocellular regions, and abnormal chondrocyte shape. This abnormal differentiation is likely to involve altered cell-matrix interactions but the mechanism is not known. To investigate the molecular basis of the collagen IX null phenotype we analyzed global differences in protein abundance between wild-type and knock-out femoral head cartilage by capillary HPLC tandem mass spectrometry. We identified 297 proteins in 3-day cartilage and 397 proteins in 21-day cartilage. Components that were differentially abundant between wild-type and collagen IX-deficient cartilage included 15 extracellular matrix proteins. Collagen IX ablation was associated with dramatically reduced COMP and matrilin-3, consistent with known interactions. Matrilin-1, matrilin-4, epiphycan, and thrombospondin-4 levels were reduced in collagen IX null cartilage, providing the first in vivo evidence for these proteins belonging to the collagen IX interactome. Thrombospondin-4 expression was reduced at the mRNA level, whereas matrilin-4 was verified as a novel collagen IX-binding protein. Furthermore, changes in TGFβ-induced protein βig-h3 and fibronectin abundance were found in the collagen IX knock-out but not associated with COMP ablation, indicating specific involvement in the abnormal collagen IX null cartilage. In addition, the more widespread expression of collagen XII in the collagen IX-deficient cartilage suggests an attempted compensatory response to the absence of collagen IX. Our differential proteomic analysis of cartilage is a novel approach to identify candidate matrix protein interactions in vivo, underpinning further analysis of mutant cartilage lacking other matrix components or harboring disease-causing mutations.
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Reversing hypomyelination in BACE1-null mice with Akt-DD overexpression.
Hu, Xiangyou; Schlanger, Rita; He, Wanxia; Macklin, Wendy B; Yan, Riqiang
2013-05-01
β-Site amyloid precursor protein convertase enzyme 1 (BACE1), a type I transmembrane aspartyl protease required to cleave amyloid precursor protein for releasing a toxic amyloid peptide, also cleaves type I and type III neuregulin-1 (Nrg-1). BACE1 deficiency in mice causes hypomyelination during development and impairs remyelination if injured. In BACE1-null mice, the abolished cleavage of neuregulin-1 by BACE1 is speculated to cause reduced myelin sheath thickness in both the central nervous system and peripheral nervous system because reduced cleavage of Nrg-1 correlates with reduced Akt phosphorylation, a downstream signaling molecule of the Nrg-1/ErbB pathway. Here we tested specifically whether increasing Akt activity alone in oligodendrocytes would be sufficient to reverse the hypomyelination phenotype in BACE1-null mice. BACE1-null mice were bred with transgenic mice expressing constitutively active Akt (Akt-DD; mutations with D(308)T and D(473)S) in oligodendrocytes. Relative to littermate BACE1-null controls, BACE1(-/-)/Akt-DD mice exhibited enhanced expression of myelin basic protein and promoter of proteolipid protein. The elevated expression of myelin proteins correlated with a thicker myelin sheath in optic nerves; comparison of quantified g ratios with statistic significance was used to confirm this reversion. However, it appeared that myelin sheath thickness in the sciatic nerves was not increased in BACE1(-/-)/Akt-DD mice, as the g ratio was not significantly different from the control. Hence, increased Akt activity in BACE1-null myelinating cells only compensates for the loss of BACE1 activity in the central nervous system, which is consistent with the observation that overexpression of Akt-DD in Schwann cells did not induce hypermyelination. Our results suggest that signaling activity other than Akt may also contribute to proper myelination in peripheral nerves.
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McCauley, Mark D.; Wang, Tiannan; Mike, Elise; Herrera, Jose; Beavers, David L.; Huang, Teng-Wei; Ward, Christopher S.; Skinner, Steven; Percy, Alan K.; Glaze, Daniel G.; Wehrens, Xander H. T.; Neul, Jeffrey L.
2013-01-01
Rett Syndrome is a neurodevelopmental disorder typically caused by mutations in Methyl-CpG-Binding Protein 2 (MECP2) in which 26% of deaths are sudden and of unknown cause. To explore the hypothesis that these deaths may be due to cardiac dysfunction, we characterized the electrocardiograms (ECGs) in 379 people with Rett syndrome and found that 18.5% show prolongation of the corrected QT interval (QTc), indicating a repolarization abnormality that can predispose to the development of an unstable fatal cardiac rhythm. Male mice lacking MeCP2 function, Mecp2Null/Y, also have prolonged QTc and show increased susceptibility to induced ventricular tachycardia. Female heterozygous null mice, Mecp2Null/+, show an age-dependent prolongation of QTc associated with ventricular tachycardia and cardiac-related death. Genetic deletion of MeCP2 function in only the nervous system was sufficient to cause long QTc and ventricular tachycardia, implicating neuronally-mediated changes to cardiac electrical conduction as a potential cause of ventricular tachycardia in Rett syndrome. The standard therapy for prolonged QTc in Rett syndrome, β-adrenergic receptor blockers, did not prevent ventricular tachycardia in Mecp2Null/Y mice. To determine whether an alternative therapy would be more appropriate, we characterized cardiomyocytes from Mecp2Null/Y mice and found increased persistent sodium current, which was normalized when cells were treated with the sodium channel-blocking anti-seizure drug phenytoin. Treatment with phenytoin reduced both QTc and sustained ventricular tachycardia in Mecp2Null/Y mice. These results demonstrate that cardiac abnormalities in Rett syndrome are secondary to abnormal nervous system control, which leads to increased persistent sodium current. Our findings suggest that treatment in people with Rett syndrome would be more effective if it targeted the increased persistent sodium current in order to prevent lethal cardiac arrhythmias. PMID:22174313
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Blevins, James E; Moralejo, Daniel H; Wolden-Hanson, Tami H; Thatcher, Brendan S; Ho, Jacqueline M; Kaiyala, Karl J; Matsumoto, Kozo
2012-12-15
CCK is hypothesized to inhibit meal size by acting at CCK1 receptors (CCK1R) on vagal afferent neurons that innervate the gastrointestinal tract and project to the hindbrain. Earlier studies have shown that obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which carry a spontaneous null mutation of the CCK1R, are hyperphagic and obese. Recent findings show that rats with CCK1R-null gene on a Fischer 344 background (Cck1r(-/-)) are lean and normophagic. In this study, the metabolic phenotype of this rat strain was further characterized. As expected, the CCK1R antagonist, devazepide, failed to stimulate food intake in the Cck1r(-/-) rats. Both Cck1r(+/+) and Cck1r(-/-) rats became diet-induced obese (DIO) when maintained on a high-fat diet relative to chow-fed controls. Cck1r(-/-) rats consumed larger meals than controls during the dark cycle and smaller meals during the light cycle. These effects were accompanied by increased food intake, total spontaneous activity, and energy expenditure during the dark cycle and an apparent reduction in respiratory quotient during the light cycle. To assess whether enhanced responsiveness to anorexigenic factors may contribute to the lean phenotype, we examined the effects of melanotan II (MTII) on food intake and body weight. We found an enhanced effect of MTII in Cck1r(-/-) rats to suppress food intake and body weight following both central and peripheral administration. These results suggest that the lean phenotype is potentially driven by increases in total spontaneous activity and energy expenditure.
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Blevins, James E.; Wolden-Hanson, Tami H.; Thatcher, Brendan S.; Ho, Jacqueline M.; Kaiyala, Karl J.; Matsumoto, Kozo
2012-01-01
CCK is hypothesized to inhibit meal size by acting at CCK1 receptors (CCK1R) on vagal afferent neurons that innervate the gastrointestinal tract and project to the hindbrain. Earlier studies have shown that obese Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which carry a spontaneous null mutation of the CCK1R, are hyperphagic and obese. Recent findings show that rats with CCK1R-null gene on a Fischer 344 background (Cck1r−/−) are lean and normophagic. In this study, the metabolic phenotype of this rat strain was further characterized. As expected, the CCK1R antagonist, devazepide, failed to stimulate food intake in the Cck1r−/− rats. Both Cck1r+/+ and Cck1r−/− rats became diet-induced obese (DIO) when maintained on a high-fat diet relative to chow-fed controls. Cck1r−/− rats consumed larger meals than controls during the dark cycle and smaller meals during the light cycle. These effects were accompanied by increased food intake, total spontaneous activity, and energy expenditure during the dark cycle and an apparent reduction in respiratory quotient during the light cycle. To assess whether enhanced responsiveness to anorexigenic factors may contribute to the lean phenotype, we examined the effects of melanotan II (MTII) on food intake and body weight. We found an enhanced effect of MTII in Cck1r−/− rats to suppress food intake and body weight following both central and peripheral administration. These results suggest that the lean phenotype is potentially driven by increases in total spontaneous activity and energy expenditure. PMID:23115121
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Gonen, Nitzan; Quinn, Alexander; O'Neill, Helen C; Koopman, Peter; Lovell-Badge, Robin
2017-01-01
During mouse sex determination, transient expression of the Y-linked gene Sry up-regulates its direct target gene Sox9, via a 3.2 kb testis specific enhancer of Sox9 (TES), which includes a core 1.4 kb element, TESCO. SOX9 activity leads to differentiation of Sertoli cells, rather than granulosa cells from the bipotential supporting cell precursor lineage. Here, we present functional analysis of TES/TESCO, using CRISPR/Cas9 genome editing in mice. Deletion of TESCO or TES reduced Sox9 expression levels in XY fetal gonads to 60 or 45% respectively relative to wild type gonads, and reduced expression of the SOX9 target Amh. Although human patients heterozygous for null mutations in SOX9, which are assumed to have 50% of normal expression, often show XY female sex reversal, mice deleted for one copy of Sox9 do not. Consistent with this, we did not observe sex reversal in either TESCO-/- or TES-/- XY embryos or adult mice. However, embryos carrying both a conditional Sox9 null allele and the TES deletion developed ovotestes. Quantitative analysis of these revealed levels of 23% expression of Sox9 compared to wild type, and a significant increase in the expression of the granulosa cell marker Foxl2. This indicates that the threshold in mice where sex reversal begins to be seen is about half that of the ~50% levels predicted in humans. Our results demonstrate that TES/TESCO is a crucial enhancer regulating Sox9 expression in the gonad, but point to the existence of additional enhancers that act redundantly.
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O’Neill, Helen C.; Koopman, Peter; Lovell-Badge, Robin
2017-01-01
During mouse sex determination, transient expression of the Y-linked gene Sry up-regulates its direct target gene Sox9, via a 3.2 kb testis specific enhancer of Sox9 (TES), which includes a core 1.4 kb element, TESCO. SOX9 activity leads to differentiation of Sertoli cells, rather than granulosa cells from the bipotential supporting cell precursor lineage. Here, we present functional analysis of TES/TESCO, using CRISPR/Cas9 genome editing in mice. Deletion of TESCO or TES reduced Sox9 expression levels in XY fetal gonads to 60 or 45% respectively relative to wild type gonads, and reduced expression of the SOX9 target Amh. Although human patients heterozygous for null mutations in SOX9, which are assumed to have 50% of normal expression, often show XY female sex reversal, mice deleted for one copy of Sox9 do not. Consistent with this, we did not observe sex reversal in either TESCO-/- or TES-/- XY embryos or adult mice. However, embryos carrying both a conditional Sox9 null allele and the TES deletion developed ovotestes. Quantitative analysis of these revealed levels of 23% expression of Sox9 compared to wild type, and a significant increase in the expression of the granulosa cell marker Foxl2. This indicates that the threshold in mice where sex reversal begins to be seen is about half that of the ~50% levels predicted in humans. Our results demonstrate that TES/TESCO is a crucial enhancer regulating Sox9 expression in the gonad, but point to the existence of additional enhancers that act redundantly. PMID:28045957
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Severe changes in colon epithelium in the Mecp2-null mouse model of Rett syndrome.
Millar-Büchner, Pamela; Philp, Amber R; Gutierrez, Noemí; Villanueva, Sandra; Kerr, Bredford; Flores, Carlos A
2016-12-01
Rett syndrome is best known due to its severe and devastating symptoms in the central nervous system. It is produced by mutations affecting the Mecp2 gene that codes for a transcription factor. Nevertheless, evidence for MECP2 activity has been reported for tissues other than those of the central nervous system. Patients affected by Rett presented with intestinal affections whose origin is still not known. We have observed that the Mecp2-null mice presented with episodes of diarrhea, and decided to study the intestinal phenotype in these mice. Mecp2-null mice or bearing the conditional intestinal deletion of MECP2 were used. Morphometirc and histologic analysis of intestine, and RT-PCR, western blot and immunodetection were perfomed on intestinal samples of the animals. Electrical parameters of the intestine were determined by Ussing chamber experiments in freshly isolated colon samples. First we determined that MECP2 protein is mainly expressed in cells of the lower part of the colonic crypts and not in the small intestine. The colon of the Mecp2-null mice was shorter than that of the wild-type. Histological analysis showed that epithelial cells of the surface have abnormal localization of key membrane proteins like ClC-2 and NHE-3 that participate in the electroneutral NaCl absorption; nevertheless, electrogenic secretion and absorption remain unaltered. We also detected an increase in a proliferation marker in the crypts of the colon samples of the Mecp2-null mice, but the specific silencing of Mecp2 from intestinal epithelium was not able to recapitulate the intestinal phenotype of the Mecp2-null mice. In summary, we showed that the colon is severely affected by Mecp2 silencing in mice. Changes in colon length and epithelial histology are similar to those observed in colitis. Changes in the localization of proteins that participate in fluid absorption can explain watery stools, but the exclusive deletion of Mecp2 from the intestine did not reproduce colon changes observed in the Mecp2-null mice, indicating the participation of other cells in this phenotype and the complex interaction between different cell types in this disease.
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Temporal and regional alterations in NMDA receptor expression in Mecp2-null mice
Blue, Mary E.; Kaufmann, Walter E.; Bressler, Joseph; Eyring, Charlotte; O’Driscoll, Cliona; Naidu, SakkuBai; Johnston, Michael V.
2014-01-01
Our previous postmortem study of girls with Rett Syndrome (RTT), a development disorder caused by MECP2 mutations, found increases in the density of NMDA receptors in the prefrontal cortex of 2–8 year-old girls, while girls older than 10 years had reductions in NMDA receptors compared to age matched controls (Blue et al., 1999b). Using [3H]-CGP to label NMDA type glutamate receptors in 2 and 7 week old wildtype (WT), Mecp2-null and Mecp2-heterozygous (HET) mice (Bird model), we found that frontal areas of the brain also exhibited a bimodal pattern in NMDA expression, with increased densities of NMDA receptors in Mecp2-null mice at 2 weeks of age, but decreased densities at 7 weeks of age. Visual cortex showed a similar pattern, while other cortical regions only exhibited changes in NMDA receptor densities at 2 weeks (retrosplenial granular) or 7 weeks (somatosensory). In thalamus of null mice, NMDA receptors were increased at 2 and 7 weeks. No significant differences in density were found between HET and WT mice at both ages. Western blots for NMDAR1 expression in frontal brain showed higher levels of expression in Mecp2-null mice at two weeks of age, but not at 1 or 7 weeks of age. Our mouse data support the notion that deficient MeCP2 function is the primary cause of the NMDA receptor changes we observed in RTT. Furthermore, the findings of regional and temporal differences in NMDA expression illustrate the importance of age and brain region in evaluating different genotypes of mice. PMID:21901842
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Tonnessen-Murray, Crystal; Ungerleider, Nathan A; Rao, Sonia G; Wasylishen, Amanda R; Frey, Wesley D; Jackson, James G
2018-05-28
p53 is a transcription factor that regulates expression of genes involved in cell cycle arrest, senescence, and apoptosis. TP53 harbors mutations that inactivate its transcriptional activity in roughly 30% of breast cancers, and these tumors are much more likely to undergo a pathological complete response to chemotherapy. Thus, the gene expression program activated by wild-type p53 contributes to a poor response. We used an in vivo genetic model system to comprehensively define the p53- and p21-dependent genes and pathways modulated in tumors following doxorubicin treatment. We identified genes differentially expressed in spontaneous mammary tumors harvested from treated MMTV-Wnt1 mice that respond poorly (Trp53+/+) or favorably (Trp53-null) and those that lack the critical senescence/arrest p53 target gene Cdkn1a. Trp53 wild-type tumors differentially expressed nearly 10-fold more genes than Trp53-null tumors after treatment. Pathway analyses showed that genes involved in cell cycle, senescence, and inflammation were enriched in treated Trp53 wild-type tumors; however, no genes/pathways were identified that adequately explain the superior cell death/tumor regression observed in Trp53-null tumors. Cdkn1a-null tumors that retained arrest capacity (responded poorly) and those that proliferated (responded well) after treatment had remarkably different gene regulation. For instance, Cdkn1a-null tumors that arrested upregulated Cdkn2a (p16), suggesting an alternative, p21-independent route to arrest. Live animal imaging of longitudinal gene expression of a senescence/inflammation gene reporter in Trp53+/+ tumors showed induction during and after chemotherapy treatment, while tumors were arrested, but expression rapidly diminished immediately upon relapse. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.
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Interleukin-6 is an essential determinant of on-time parturition in the mouse.
Robertson, Sarah A; Christiaens, Inge; Dorian, Camilla L; Zaragoza, Dean B; Care, Alison S; Banks, Anke M; Olson, David M
2010-08-01
IL-6 abundance in amniotic fluid and uterine tissues increases in late gestation or with infection-associated preterm labor. A role in regulation of labor onset is suggested by observations that IL-6 increases expression of genes controlling prostaglandin synthesis and signaling in isolated uterine cells, but whether IL-6 is essential for normal parturition is unknown. To evaluate the physiological role of IL-6 in parturition in mice, we investigated the effect of Il6 null mutation on the timing of parturition and expression of genes associated with uterine activation. Il6 null mutant mice delivered 24 h later than wild-type mice, although circulating progesterone fell similarly in both genotypes during the prepartal period. Il6 null mutant mice were also refractory to low doses of lipopolysaccharide sufficient to induce preterm delivery in wild-type mice. The characteristic late-gestation elevation in uterine expression of Oxtr mRNA encoding oxytocin receptor, and peripartal increases in Ptgfr and Ptgs2 mRNAs regulating prostaglandin synthesis and signaling were delayed by 24 h in Il6 null mutant mice. Conversely, Ptger4 mRNA encoding the prostaglandin E receptor-4 was abnormally elevated in late-gestation in Il6 null mutant mice. Administration of recombinant IL-6 from d 11.5 postcoitum until term restored the normal timing of delivery and normalized Ptger4 mRNA expression in late gestation. We conclude that IL-6 has a key role in controlling the progression of events culminating in parturition and that it acts downstream of luteolysis in the uterus to regulate genes involved in the prostaglandin-mediated uterine activation cascade.
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Hystad, S M; Martin, J M; Graybosch, R A; Giroux, M J
2015-08-01
Characterized novel mutations present at Ppo loci account for the substantial reduction of the total kernel PPO activity present in a putative null Ppo - A1 genetic background. Wheat (Triticum aestivum) polyphenol oxidase (PPO) contributes to the time-dependent discoloration of Asian noodles. Wheat contains multiple paralogous and orthologous Ppo genes, Ppo-A1, Ppo-D1, Ppo-A2, Ppo-D2, and Ppo-B2, expressed in wheat kernels. To date, wheat noodle color improvement efforts have focused on breeding cultivars containing Ppo-D1 and Ppo-A1 alleles conferring reduced PPO activity. A major impediment to wheat quality improvement is a lack of additional Ppo alleles conferring reduced kernel PPO. In this study, a previously reported very low PPO line, 07OR1074, was found to contain a novel allele at Ppo-A2 and null alleles at the Ppo-A1 and Ppo-D1 loci. To examine the impact of each mutation upon kernel PPO, populations were generated from crosses between 07OR1074 and the hard white spring wheat cultivars Choteau and Vida. Expression analysis using RNA-seq demonstrated no detectable Ppo-A1 transcripts in 07OR1074 while Ppo-D1 transcripts were present at less than 10% of that seen in Choteau and Vida. Novel markers specific for the Ppo-D1 and Ppo-A2 mutations discovered in 07OR1074, along with the Ppo-A1 STS marker, were used to screen segregating populations. Evaluation of lines indicated a substantial genotypic effect on PPO with Ppo-A1 and Ppo-D1 alleles contributing significantly to total PPO in both populations. These results show that the novel mutations in Ppo-A1 and Ppo-D1 present in 07OR1074 are both important to lowering overall wheat seed PPO activity and may be useful to produce more desirable and marketable wheat-based products.
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Kwiatkowski, David J; Zhang, Hongbing; Bandura, Jennifer L; Heiberger, Kristina M; Glogauer, Michael; el-Hashemite, Nisreen; Onda, Hiroaki
2002-03-01
Tuberous sclerosis (TSC) is a autosomal dominant genetic disorder caused by mutations in either TSC1 or TSC2, and characterized by benign hamartoma growth. We developed a murine model of Tsc1 disease by gene targeting. Tsc1 null embryos die at mid-gestation from a failure of liver development. Tsc1 heterozygotes develop kidney cystadenomas and liver hemangiomas at high frequency, but the incidence of kidney tumors is somewhat lower than in Tsc2 heterozygote mice. Liver hemangiomas were more common, more severe and caused higher mortality in female than in male Tsc1 heterozygotes. Tsc1 null embryo fibroblast lines have persistent phosphorylation of the p70S6K (S6K) and its substrate S6, that is sensitive to treatment with rapamycin, indicating constitutive activation of the mTOR-S6K pathway due to loss of the Tsc1 protein, hamartin. Hyperphosphorylation of S6 is also seen in kidney tumors in the heterozygote mice, suggesting that inhibition of this pathway may have benefit in control of TSC hamartomas.
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Loss-of-Function PCSK9 Mutations Are Not Associated With Alzheimer Disease.
Paquette, Martine; Saavedra, Yascara Grisel Luna; Poirier, Judes; Théroux, Louise; Dea, Doris; Baass, Alexis; Dufour, Robert
2018-03-01
Hypercholesterolemia is a major risk factor for the late-onset form of Alzheimer disease (AD). Loss-of-function (LOF) mutations of PCSK9 and PCSK9 inhibitors lower low-density lipoprotein cholesterol (LDL-C) and have been associated with a reduced risk of cardiovascular disease. The aim of this study was to examine the effect of PCSK9 LOF variants on risk and age of onset of AD. A total of 878 participants (410 controls and 468 AD cases) from the Quebec Founder Population were included in the study. Fifty-four (6.2%) participants carried the R46L mutation, whereas 226 (26.2%) participants carried the InsLEU mutation. There was no protective or no deleterious effect of carrying PCSK9 LOF mutations on AD prevalence nor on age of onset, even when stratified by apolipoprotein E epsilon 4 genotype or by gender. Our data indicate that carrying PCSK9 LOF mutations has a neutral effect on neurocognitive health and the prevalence of AD.
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Hodi, F Stephen; Corless, Christopher L; Giobbie-Hurder, Anita; Fletcher, Jonathan A; Zhu, Meijun; Marino-Enriquez, Adrian; Friedlander, Philip; Gonzalez, Rene; Weber, Jeffrey S; Gajewski, Thomas F; O'Day, Steven J; Kim, Kevin B; Lawrence, Donald; Flaherty, Keith T; Luke, Jason J; Collichio, Frances A; Ernstoff, Marc S; Heinrich, Michael C; Beadling, Carol; Zukotynski, Katherine A; Yap, Jeffrey T; Van den Abbeele, Annick D; Demetri, George D; Fisher, David E
2013-09-10
Amplifications and mutations in the KIT proto-oncogene in subsets of melanomas provide therapeutic opportunities. We conducted a multicenter phase II trial of imatinib in metastatic mucosal, acral, or chronically sun-damaged (CSD) melanoma with KIT amplifications and/or mutations. Patients received imatinib 400 mg once per day or 400 mg twice per day if there was no initial response. Dose reductions were permitted for treatment-related toxicities. Additional oncogene mutation screening was performed by mass spectroscopy. Twenty-five patients were enrolled (24 evaluable). Eight patients (33%) had tumors with KIT mutations, 11 (46%) with KIT amplifications, and five (21%) with both. Median follow-up was 10.6 months (range, 3.7 to 27.1 months). Best overall response rate (BORR) was 29% (21% excluding nonconfirmed responses) with a two-stage 95% CI of 13% to 51%. BORR was significantly greater than the hypothesized null of 5% and statistically significantly different by mutation status (7 of 13 or 54% KIT mutated v 0% KIT amplified only). There were no statistical differences in rates of progression or survival by mutation status or by melanoma site. The overall disease control rate was 50% but varied significantly by KIT mutation status (77% mutated v 18% amplified). Four patients harbored pretreatment NRAS mutations, and one patient acquired increased KIT amplification after treatment. Melanomas that arise on mucosal, acral, or CSD skin should be assessed for KIT mutations. Imatinib can be effective when tumors harbor KIT mutations, but not if KIT is amplified only. NRAS mutations and KIT copy number gain may be mechanisms of therapeutic resistance to imatinib.
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Functional Analysis of Human NF1 in Drosophila
2008-12-01
also have learning problem. Such learning phenotypes have been recapitulated in animal models, including in mouse and Drosophila mutants. This proposal...by examining the phenotypes of mutated human genes expressed in Drosophila NF1 null mutants. We also propose that Gsα/NF1 activated AC pathway...in both Drosophila and mouse NF1 models. Our previous work has shown that defective cAMP signaling leads to the learning phenotype in Drosophila Nf1
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Strong effects of ionizing radiation from Chernobyl on mutation rates
NASA Astrophysics Data System (ADS)
Møller, Anders Pape; Mousseau, Timothy A.
2015-02-01
In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material.
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Sitarska, Ewa; Xu, Junjie; Park, Seungmee; Liu, Xiaoxia; Quade, Bradley; Stepien, Karolina; Sugita, Kyoko; Brautigam, Chad A; Sugita, Shuzo; Rizo, Josep
2017-05-06
Munc18-1 orchestrates SNARE complex assembly together with Munc13-1 to mediate neurotransmitter release. Munc18-1 binds to synaptobrevin, but the relevance of this interaction and its relation to Munc13 function are unclear. NMR experiments now show that Munc18-1 binds specifically and non-specifically to synaptobrevin. Specific binding is inhibited by a L348R mutation in Munc18-1 and enhanced by a D326K mutation designed to disrupt the 'furled conformation' of a Munc18-1 loop. Correspondingly, the activity of Munc18-1 in reconstitution assays that require Munc18-1 and Munc13-1 for membrane fusion is stimulated by the D326K mutation and inhibited by the L348R mutation. Moreover, the D326K mutation allows Munc13-1-independent fusion and leads to a gain-of-function in rescue experiments in Caenorhabditis elegans unc-18 nulls. Together with previous studies, our data support a model whereby Munc18-1 acts as a template for SNARE complex assembly, and autoinhibition of synaptobrevin binding contributes to enabling regulation of neurotransmitter release by Munc13-1.
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Strong effects of ionizing radiation from Chernobyl on mutation rates.
Møller, Anders Pape; Mousseau, Timothy A
2015-02-10
In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material.
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Seven functional classes of Barth syndrome mutation.
Whited, Kevin; Baile, Matthew G; Currier, Pamela; Claypool, Steven M
2013-02-01
Patients with Barth syndrome (BTHS), a rare X-linked disease, suffer from skeletal and cardiomyopathy and bouts of cyclic neutropenia. The causative gene encodes tafazzin, a transacylase, which is the major determinant of the final acyl chain composition of the mitochondrial-specific phospholipid, CL. In addition to numerous frame shift and splice-site mutations, 36 missense mutations have been associated with BTHS. Previously, we established a BTHS-mutant panel in the yeast Saccharomyces cerevisiae that successfully models 18/21 conserved pathogenic missense mutations and defined the loss-of-function mechanism associated with a subset of the mutant tafazzins. Here, we report the biochemical and cell biological characterization of the rest of the yeast BTHS-mutant panel and in so doing identify three additional modes of tafazzin dysfunction. The largest group of mutant tafazzins is catalytically null, two mutants encode hypomorphic alleles, and another two mutants are temperature sensitive. Additionally, we have expanded the defects associated with previously characterized matrix-mislocalized-mutant tafazzins to include the rapid degradation of aggregation-prone polypeptides that correctly localize to the mitochondrial IMS. In sum, our in-depth characterization of the yeast BTHS-mutant panel has identified seven functional classes of BTHS mutation.
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AlGaN/GaN High Electron Mobility Transistor-Based Biosensor for the Detection of C-Reactive Protein
Lee, Hee Ho; Bae, Myunghan; Jo, Sung-Hyun; Shin, Jang-Kyoo; Son, Dong Hyeok; Won, Chul-Ho; Jeong, Hyun-Min; Lee, Jung-Hee; Kang, Shin-Won
2015-01-01
In this paper, we propose an AlGaN/GaN high electron mobility transistor (HEMT)-based biosensor for the detection of C-reactive protein (CRP) using a null-balancing circuit. A null-balancing circuit was used to measure the output voltage of the sensor directly. The output voltage of the proposed biosensor was varied by antigen-antibody interactions on the gate surface due to CRP charges. The AlGaN/GaN HFET-based biosensor with null-balancing circuit applied shows that CRP can be detected in a wide range of concentrations, varying from 10 ng/mL to 1000 ng/mL. X-ray photoelectron spectroscopy was carried out to verify the immobilization of self-assembled monolayer with Au on the gated region. PMID:26225981
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Novel C8orf37 mutations cause retinitis pigmentosa in consanguineous families of Pakistani origin
Ravesh, Zeinab; El Asrag, Mohammed E.; Weisschuh, Nicole; McKibbin, Martin; Reuter, Peggy; Watson, Christopher M.; Baumann, Britta; Poulter, James A.; Sajid, Sundus; Panagiotou, Evangelia S.; O’Sullivan, James; Abdelhamed, Zakia; Bonin, Michael; Soltanifar, Mehdi; Black, Graeme C.M.; Din, Muhammad Amin-ud; Toomes, Carmel; Ansar, Muhammad; Inglehearn, Chris F.; Wissinger, Bernd
2015-01-01
Purpose To investigate the molecular basis of retinitis pigmentosa in two consanguineous families of Pakistani origin with multiple affected members. Methods Homozygosity mapping and Sanger sequencing of candidate genes were performed in one family while the other was analyzed with whole exome next-generation sequencing. A minigene splicing assay was used to confirm the splicing defects. Results In family MA48, a novel homozygous nucleotide substitution in C8orf37, c.244–2A>C, that disrupted the consensus splice acceptor site of exon 3 was found. The minigene splicing assay revealed that this mutation activated a cryptic splice site within exon 3, causing a 22 bp deletion in the transcript that is predicted to lead to a frameshift followed by premature protein truncation. In family MA13, a novel homozygous null mutation in C8orf37, c.555G>A, p.W185*, was identified. Both mutations segregated with the disease phenotype as expected in a recessive manner and were absent in 8,244 unrelated individuals of South Asian origin. Conclusions In this report, we describe C8orf37 mutations that cause retinal dystrophy in two families of Pakistani origin, contributing further data on the phenotype and the spectrum of mutations in this form of retinitis pigmentosa. PMID:25802487
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Pereiro, Ines; Piñeiro-Gallego, Teresa; Baiget, Montserrat; Borrego, Salud; Ayuso, Carmen; Searby, Charles; Nishimura, Darryl
2010-01-01
Purpose Bardet-Biedl syndrome (BBS, OMIM 209900) is a rare multi-organ disorder in which BBS patients manifest a variable phenotype that includes retinal dystrophy, polydactyly, mental delay, obesity, and also reproductive tract and renal abnormalities. Mutations in 14 genes (BBS1–BBS14) are found in 70% of the patients, indicating that additional mutations in known and new BBS genes remain to be identified. Therefore, the molecular diagnosis of this complex disorder is a challenging task. Methods In this study we show the use of the genome-wide homozygosity mapping strategy in the mutation detection of nine Caucasian BBS families, eight of them consanguineous and one from the same geographic area with no proven consanguinity. Results We identified the disease-causing mutation in six of the families studied, five of which had novel sequence variants in BBS3, BBS6, and BBS12. This is the first null mutation reported in BBS3. Furthermore, this approach defined homozygous candidate regions that could harbor potential candidate genes for BBS in three of the families. Conclusions These findings further underline the importance of homozygosity mapping as a useful technology for diagnosis in small consanguineous families with a complex disease like BBS. PMID:20142850
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Espitia-Pérez, Lyda; Sosa, Milton Quintana; Salcedo-Arteaga, Shirley; León-Mejía, Grethel; Hoyos-Giraldo, Luz Stella; Brango, Hugo; Kvitko, Katia; da Silva, Juliana; Henriques, João A P
2016-09-15
Increasing evidence suggest that occupational exposure to open-cast coal mining residues like dust particles, heavy metals and Polycyclic Aromatic Hydrocarbons (PAHs) may cause a wide range of DNA damage and genomic instability that could be associated to initial steps in cancer development and other work-related diseases. The aim of our study was to evaluate if key polymorphisms in metabolism genes CYP1A1Msp1, GSTM1Null, GSTT1Null and DNA repair genes XRCC1Arg194Trp and hOGG1Ser326Cys could modify individual susceptibility to adverse coal exposure effects, considering the DNA damage (Comet assay) and micronucleus formation in lymphocytes (CBMN) and buccal mucosa cells (BMNCyt) as endpoints for genotoxicity. The study population is comprised of 200 healthy male subjects, 100 open-cast coal-mining workers from "El Cerrejón" (world's largest open-cast coal mine located in Guajira - Colombia) and 100 non-exposed referents from general population. The data revealed a significant increase of CBMN frequency in peripheral lymphocytes of occupationally exposed workers carrying the wild-type variant of GSTT1 (+) gene. Exposed subjects carrying GSTT1null polymorphism showed a lower micronucleus frequency compared with their positive counterparts (FR: 0.83; P=0.04), while BMNCyt, frequency and Comet assay parameters in lymphocytes: Damage Index (DI) and percentage of DNA in the tail (Tail % DNA) were significantly higher in exposed workers with the GSTM1Null polymorphism. Other exfoliated buccal mucosa abnormalities related to cell death (Karyorrhexis and Karyolysis) were increased in GSTT/M1Null carriers. Nuclear buds were significantly higher in workers carrying the CYP1A1Msp1 (m1/m2, m2/m2) allele. Moreover, BMNCyt frequency and Comet assay parameters were significantly lower in exposed carriers of XRCC1Arg194Trp (Arg/Trp, Trp/Trp) and hOGG1Ser326Cys (Ser/Cys, Cys/Cys), thereby providing new data to the increasing evidence about the protective role of these polymorphisms. This modulation may involve specific and differentiated pathways in different tissues that also may cause a differential sensitivity related to differential induction of some enzymes. Copyright © 2016 Elsevier B.V. All rights reserved.
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Copb2 is essential for embryogenesis and hypomorphic mutations cause human microcephaly.
DiStasio, Andrew; Driver, Ashley; Sund, Kristen; Donlin, Milene; Muraleedharan, Ranjith M; Pooya, Shabnam; Kline-Fath, Beth; Kaufman, Kenneth M; Prows, Cynthia A; Schorry, Elizabeth; Dasgupta, Biplab; Stottmann, Rolf W
2017-12-15
Primary microcephaly is a congenital brain malformation characterized by a head circumference less than three standard deviations below the mean for age and sex and results in moderate to severe mental deficiencies and decreased lifespan. We recently studied two children with primary microcephaly in an otherwise unaffected family. Exome sequencing identified an autosomal recessive mutation leading to an amino acid substitution in a WD40 domain of the highly conserved Coatomer Protein Complex, Subunit Beta 2 (COPB2). To study the role of Copb2 in neural development, we utilized genome-editing technology to generate an allelic series in the mouse. Two independent null alleles revealed that Copb2 is essential for early stages of embryogenesis. Mice homozygous for the patient variant (Copb2R254C/R254C) appear to have a grossly normal phenotype, likely due to differences in corticogenesis between the two species. Strikingly, mice heterozygous for the patient mutation and a null allele (Copb2R254C/Zfn) show a severe perinatal phenotype including low neonatal weight, significantly increased apoptosis in the brain, and death within the first week of life. Immunostaining of the Copb2R254C/Zfnbrain revealed a reduction in layer V (CTIP2+) neurons, while the overall cell density of the cortex is unchanged. Moreover, neurospheres derived from animals with Copb2 variants grew less than control. These results identify a general requirement for COPB2 in embryogenesis and a specific role in corticogenesis. We further demonstrate the utility of CRISPR-Cas9 generated mouse models in the study of potential pathogenicity of variants of potential clinical interest. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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Liu, Zhongle; Myers, Lawrence C
2017-11-01
Long-term azole treatment of patients with chronic Candida albicans infections can lead to drug resistance. Gain-of-function (GOF) mutations in the transcription factor Mrr1 and the consequent transcriptional activation of MDR1 , a drug efflux coding gene, is a common pathway by which this human fungal pathogen acquires fluconazole resistance. This work elucidates the previously unknown downstream transcription mechanisms utilized by hyperactive Mrr1. We identified the Swi/Snf chromatin remodeling complex as a key coactivator for Mrr1, which is required to maintain basal and induced open chromatin, and Mrr1 occupancy, at the MDR1 promoter. Deletion of snf2 , the catalytic subunit of Swi/Snf, largely abrogates the increases in MDR1 expression and fluconazole MIC observed in MRR1 GOF mutant strains. Mediator positively and negatively regulates key Mrr1 target promoters. Deletion of the Mediator tail module med3 subunit reduces, but does not eliminate, the increased MDR1 expression and fluconazole MIC conferred by MRR1 GOF mutations. Eliminating the kinase activity of the Mediator Ssn3 subunit suppresses the decreased MDR1 expression and fluconazole MIC of the snf2 null mutation in MRR1 GOF strains. Ssn3 deletion also suppresses MDR1 promoter histone displacement defects in snf2 null mutants. The combination of this work with studies on other hyperactive zinc cluster transcription factors that confer azole resistance in fungal pathogens reveals a complex picture where the induction of drug efflux pump expression requires the coordination of multiple coactivators. The observed variations in transcription factor and target promoter dependence of this process may make the search for azole sensitivity-restoring small molecules more complicated. Copyright © 2017 American Society for Microbiology.
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Westbroek, Wendy; Nguyen, Matthew; Siebert, Marina; Lindstrom, Taylor; Burnett, Robert A.; Aflaki, Elma; Jung, Olive; Tamargo, Rafael; Rodriguez-Gil, Jorge L.; Acosta, Walter; Hendrix, An; Behre, Bahafta; Tayebi, Nahid; Fujiwara, Hideji; Sidhu, Rohini; Renvoise, Benoit; Ginns, Edward I.; Dutra, Amalia; Pak, Evgenia; Cramer, Carole; Ory, Daniel S.; Pavan, William J.
2016-01-01
ABSTRACT Glucocerebrosidase is a lysosomal hydrolase involved in the breakdown of glucosylceramide. Gaucher disease, a recessive lysosomal storage disorder, is caused by mutations in the gene GBA1. Dysfunctional glucocerebrosidase leads to accumulation of glucosylceramide and glycosylsphingosine in various cell types and organs. Mutations in GBA1 are also a common genetic risk factor for Parkinson disease and related synucleinopathies. In recent years, research on the pathophysiology of Gaucher disease, the molecular link between Gaucher and Parkinson disease, and novel therapeutics, have accelerated the need for relevant cell models with GBA1 mutations. Although induced pluripotent stem cells, primary rodent neurons, and transfected neuroblastoma cell lines have been used to study the effect of glucocerebrosidase deficiency on neuronal function, these models have limitations because of challenges in culturing and propagating the cells, low yield, and the introduction of exogenous mutant GBA1. To address some of these difficulties, we established a high yield, easy-to-culture mouse neuronal cell model with nearly complete glucocerebrosidase deficiency representative of Gaucher disease. We successfully immortalized cortical neurons from embryonic null allele gba−/− mice and the control littermate (gba+/+) by infecting differentiated primary cortical neurons in culture with an EF1α-SV40T lentivirus. Immortalized gba−/− neurons lack glucocerebrosidase protein and enzyme activity, and exhibit a dramatic increase in glucosylceramide and glucosylsphingosine accumulation, enlarged lysosomes, and an impaired ATP-dependent calcium-influx response; these phenotypical characteristics were absent in gba+/+ neurons. This null allele gba−/− mouse neuronal model provides a much-needed tool to study the pathophysiology of Gaucher disease and to evaluate new therapies. PMID:27482815
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Defective insulin secretion in hepatocyte nuclear factor 1alpha-deficient mice.
Pontoglio, M; Sreenan, S; Roe, M; Pugh, W; Ostrega, D; Doyen, A; Pick, A J; Baldwin, A; Velho, G; Froguel, P; Levisetti, M; Bonner-Weir, S; Bell, G I; Yaniv, M; Polonsky, K S
1998-01-01
Mutations in the gene for the transcription factor hepatocyte nuclear factor (HNF) 1alpha cause maturity-onset diabetes of the young (MODY) 3, a form of diabetes that results from defects in insulin secretion. Since the nature of these defects has not been defined, we compared insulin secretory function in heterozygous [HNF-1alpha (+/-)] or homozygous [HNF-1alpha (-/-)] mice with null mutations in the HNF-1alpha gene with their wild-type littermates [HNF-1alpha (+/+)]. Blood glucose concentrations were similar in HNF-1alpha (+/+) and (+/-) mice (7.8+/-0.2 and 7.9+/-0.3 mM), but were significantly higher in the HNF-1alpha (-/-) mice (13.1+/-0.7 mM, P < 0.001). Insulin secretory responses to glucose and arginine in the perfused pancreas and perifused islets from HNF-1alpha (-/-) mice were < 15% of the values in the other two groups and were associated with similar reductions in intracellular Ca2+ responses. These defects were not due to a decrease in glucokinase or insulin gene transcription. beta cell mass adjusted for body weight was not reduced in the (-/-) animals, although pancreatic insulin content adjusted for pancreas weight was slightly lower (0.06+/-0.01 vs. 0.10+/-0.01 microg/mg, P < 0.01) than in the (+/+) animals. In summary, a null mutation in the HNF-1alpha gene in homozygous mice leads to diabetes due to alterations in the pathways that regulate beta cell responses to secretagogues including glucose and arginine. These results provide further evidence in support of a key role for HNF-1alpha in the maintenance of normal beta cell function. PMID:9593777
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KIAA0556 is a novel ciliary basal body component mutated in Joubert syndrome.
Sanders, Anna A W M; de Vrieze, Erik; Alazami, Anas M; Alzahrani, Fatema; Malarkey, Erik B; Sorusch, Nasrin; Tebbe, Lars; Kuhns, Stefanie; van Dam, Teunis J P; Alhashem, Amal; Tabarki, Brahim; Lu, Qianhao; Lambacher, Nils J; Kennedy, Julie E; Bowie, Rachel V; Hetterschijt, Lisette; van Beersum, Sylvia; van Reeuwijk, Jeroen; Boldt, Karsten; Kremer, Hannie; Kesterson, Robert A; Monies, Dorota; Abouelhoda, Mohamed; Roepman, Ronald; Huynen, Martijn H; Ueffing, Marius; Russell, Rob B; Wolfrum, Uwe; Yoder, Bradley K; van Wijk, Erwin; Alkuraya, Fowzan S; Blacque, Oliver E
2015-12-29
Joubert syndrome (JBTS) and related disorders are defined by cerebellar malformation (molar tooth sign), together with neurological symptoms of variable expressivity. The ciliary basis of Joubert syndrome related disorders frequently extends the phenotype to tissues such as the eye, kidney, skeleton and craniofacial structures. Using autozygome and exome analyses, we identified a null mutation in KIAA0556 in a multiplex consanguineous family with hallmark features of mild Joubert syndrome. Patient-derived fibroblasts displayed reduced ciliogenesis potential and abnormally elongated cilia. Investigation of disease pathophysiology revealed that Kiaa0556 (-/-) null mice possess a Joubert syndrome-associated brain-restricted phenotype. Functional studies in Caenorhabditis elegans nematodes and cultured human cells support a conserved ciliary role for KIAA0556 linked to microtubule regulation. First, nematode KIAA0556 is expressed almost exclusively in ciliated cells, and the worm and human KIAA0556 proteins are enriched at the ciliary base. Second, C. elegans KIAA0056 regulates ciliary A-tubule number and genetically interacts with an ARL13B (JBTS8) orthologue to control cilium integrity. Third, human KIAA0556 binds to microtubules in vitro and appears to stabilise microtubule networks when overexpressed. Finally, human KIAA0556 biochemically interacts with ciliary proteins and p60/p80 katanins. The latter form a microtubule-severing enzyme complex that regulates microtubule dynamics as well as ciliary functions. We have identified KIAA0556 as a novel microtubule-associated ciliary base protein mutated in Joubert syndrome. Consistent with the mild patient phenotype, our nematode, mice and human cell data support the notion that KIAA0556 has a relatively subtle and variable cilia-related function, which we propose is related to microtubule regulation.
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The unique GGA clathrin adaptor of Drosophila melanogaster is not essential.
Luan, Shan; Ilvarsonn, Anne M; Eissenberg, Joel C
2012-01-01
The Golgi-localized, γ-ear-containing, ARF binding proteins (GGAs) are a highly conserved family of monomeric clathrin adaptor proteins implicated in clathrin-mediated protein sorting between the trans-Golgi network and endosomes. GGA RNAi knockdowns in Drosophila have resulted in conflicting data concerning whether the Drosophila GGA (dGGA) is essential. The goal of this study was to define the null phenotype for the unique Drosophila GGA. We describe two independently derived dGGA mutations. Neither allele expresses detectable dGGA protein. Homozygous and hemizygous flies with each allele are viable and fertile. In contrast to a previous report using RNAi knockdown, GGA mutant flies show no evidence of age-dependent retinal degeneration or cathepsin missorting. Our results demonstrate that several of the previous RNAi knockdown phenotypes were the result of off-target effects. However, GGA null flies are hypersensitive to dietary chloroquine and to starvation, implicating GGA in lysosomal function and autophagy.
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Bischof, Jocelyn M; Stewart, Colin L; Wevrick, Rachel
2007-11-15
Prader-Willi syndrome (PWS) is an imprinted genetic obesity disorder characterized by abnormalities of growth and metabolism. Multiple mouse models with deficiency of one or more PWS candidate genes have partially correlated individual genes with aspects of the PWS phenotype, although the genetic origin of defects in growth and metabolism has not been elucidated. Gene-targeted mutation of the PWS candidate gene Magel2 in mice causes altered circadian rhythm output and reduced motor activity. We now report that Magel2-null mice exhibit neonatal growth retardation, excessive weight gain after weaning, and increased adiposity with altered metabolism in adulthood, recapitulating fundamental aspects of the PWS phenotype. Magel2-null mice provide an important opportunity to examine the physiological basis for PWS neonatal failure to thrive and post-weaning weight gain and for the relationships among circadian rhythm, feeding behavior, and metabolism.
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Keratin 17 null mice exhibit age- and strain-dependent alopecia.
McGowan, Kevin M; Tong, Xuemei; Colucci-Guyon, Emma; Langa, Francina; Babinet, Charles; Coulombe, Pierre A
2002-06-01
Onset of type I keratin 17 (K17) synthesis marks the adoption of an appendageal fate within embryonic ectoderm, and its expression persists in specific cell types within mature hair, glands, and nail. We report that K17 null mice develop severe alopecia during the first week postbirth, correlating with hair fragility, alterations in follicular histology, and apoptosis in matrix cells. These alterations are incompletely penetrant and normalize starting with the first postnatal cycle. Absence of a hair phenotype correlates with a genetic strain-dependent compensation by related keratins, including K16. These findings reveal a crucial role for K17 in the structural integrity of the first hair produced and the survival of hair-producing cells. Given that identical inherited mutations in this gene can cause either pachyonychia congenita or steatocystoma multiplex, the features of this mouse model suggest that this clinical heterogeneity arises from a cell type-specific, genetically determined compensation by related keratins.
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Paszko, Z; Sromek, M; Czetwertynska, M; Skasko, E; Czapczak, D; Wisniewska, A; Prokurat, A; Chrupek, M; Jagielska, A; Kozlowicz-Gudzinska, I
2007-12-01
We aimed to investigate the occurrence and types of pathogenic mutations in the RET gene in patients with MTC of the Central Poland population and in their relatives. DNA was extracted from the peripheral blood lymphocytes of a total of 330 persons, including 235 MTC patients and 95 of their unaffected kindred's. Exons 10, 11, 13, 14, 15 and 16 of the RET gene were amplified by PCR and sequenced. Sixty-seven people were found to carry pathogenic, germline mutations in the RET gene. In exon 10, C609F, C609R and C609Y (3 families), C618G, C618F (2 families), and C620G (4 families) mutations were identified. In exon 11, C634R (8 families) and C649L mutations (1 patient) were found. Five families carried Y791F mutation in exon 13. One patient with PTC revealed the presence of a Y791F mutation. In 3 families, exon 14 of the RET gene harbored the following mutations: V804L (1 patient), E819K (1 patient) and R844Q (1 patient). In 1 family, the S891A mutation was identified in exon 15, 3 families were found to carry mutations in exon16, R912P in 1 family and M918T in 2 families. In summary, of the 235 patients affected by MTC, 46 (19.6%) carried pathogenic RET gene mutations, 1 patient with RET mutation had kidney carcinoma, and 1 had PTC. The results show the occurrence of a variety of mutations prevalent in patients with MTC in the population of Central Poland. These results may contribute to a better diagnosis of medullary thyroid carcinoma.
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Patterns in the English language: phonological networks, percolation and assembly models
NASA Astrophysics Data System (ADS)
Stella, Massimo; Brede, Markus
2015-05-01
In this paper we provide a quantitative framework for the study of phonological networks (PNs) for the English language by carrying out principled comparisons to null models, either based on site percolation, randomization techniques, or network growth models. In contrast to previous work, we mainly focus on null models that reproduce lower order characteristics of the empirical data. We find that artificial networks matching connectivity properties of the English PN are exceedingly rare: this leads to the hypothesis that the word repertoire might have been assembled over time by preferentially introducing new words which are small modifications of old words. Our null models are able to explain the ‘power-law-like’ part of the degree distributions and generally retrieve qualitative features of the PN such as high clustering, high assortativity coefficient and small-world characteristics. However, the detailed comparison to expectations from null models also points out significant differences, suggesting the presence of additional constraints in word assembly. Key constraints we identify are the avoidance of large degrees, the avoidance of triadic closure and the avoidance of large non-percolating clusters.
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Fedyna, Alison; Drayna, Dennis; Kang, Changsoo
2010-01-01
Stuttering is a disorder which affects the fluency of speech. It has been shown to have high heritability, and has recently been linked to mutations in the GNPTAB gene. One such mutation, Glu1200Lys, has been repeatedly observed in unrelated families and individual cases. Eight unrelated individuals carrying this mutation were analyzed in an effort to distinguish whether these arise from repeated mutation at the same site, or whether they represent a founder mutation with a single origin. Results show that all 12 chromosomes carrying this mutation share a common haplotype in this region, indicating it is a founder mutation. Further analysis estimated the age of this allele to be ~572 generations. Construction of a cladogram tracing the mutation through our study sample also supports the founder mutation hypothesis. PMID:20944643
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Progranulin as a therapeutic target for dementia.
Galimberti, Daniela; Fenoglio, Chiara; Scarpini, Elio
2018-06-22
Progranulin (PGRN) is an acrosomal glycoprotein that is synthesized during spermatogenesis. It is overexpressed in tumors and has anti-inflammatory properties. The protein may be cleaved into granulins which display pro-inflammatory properties. In 2006, mutations in progranulin gene (GRN) that cause haploinsufficiency were found in familial cases of frontotemporal dementia (FTD). Patients with null mutations in GRN display very low-plasma PGRN levels; this analysis is useful for identifying mutation carriers, independent of the clinical presentation, and in those before the appearance of symptoms. Areas covered: Here, we review the current knowledge of PGRN physiological functions and GRN mutations associated with FTD; we also summarize state of the art clinical trials and those compounds able to replace PGRN loss in preclinical models. Expert opinion: PGRN represents a promising therapeutic target for FTD. Cohorts suitable for treatment, ideally at the preclinical stage, where pathogenic mechanisms ongoing in the brain are targeted, are available. However, PGRN may have side effects, such as the risk of tumorigenesis, and the risk/benefit ratio of any intervention cannot be predicted. Furthermore, at present, the situation is complicated by the absence of adequate outcome measures.
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The detection of large deletions or duplications in genomic DNA.
Armour, J A L; Barton, D E; Cockburn, D J; Taylor, G R
2002-11-01
While methods for the detection of point mutations and small insertions or deletions in genomic DNA are well established, the detection of larger (>100 bp) genomic duplications or deletions can be more difficult. Most mutation scanning methods use PCR as a first step, but the subsequent analyses are usually qualitative rather than quantitative. Gene dosage methods based on PCR need to be quantitative (i.e., they should report molar quantities of starting material) or semi-quantitative (i.e., they should report gene dosage relative to an internal standard). Without some sort of quantitation, heterozygous deletions and duplications may be overlooked and therefore be under-ascertained. Gene dosage methods provide the additional benefit of reporting allele drop-out in the PCR. This could impact on SNP surveys, where large-scale genotyping may miss null alleles. Here we review recent developments in techniques for the detection of this type of mutation and compare their relative strengths and weaknesses. We emphasize that comprehensive mutation analysis should include scanning for large insertions and deletions and duplications. Copyright 2002 Wiley-Liss, Inc.
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Scott, John W; Park, Elizabeth; Rodriguiz, Ramona M; Oakhill, Jonathan S; Issa, Samah M A; O'Brien, Matthew T; Dite, Toby A; Langendorf, Christopher G; Wetsel, William C; Means, Anthony R; Kemp, Bruce E
2015-09-23
Mutations that reduce expression or give rise to a Thr85Ser (T85S) mutation of Ca(2+)-CaM-dependent protein kinase kinase-2 (CaMKK2) have been implicated in behavioural disorders such as anxiety, bipolar and schizophrenia in humans. Here we report that Thr85 is an autophosphorylation site that endows CaMKK2 with a molecular memory that enables sustained autonomous activation following an initial, transient Ca(2+) signal. Conversely, autophosphorylation of Ser85 in the T85S mutant fails to generate autonomous activity but instead causes a partial loss of CaMKK2 activity. The loss of autonomous activity in the mutant can be rescued by blocking glycogen synthase kinase-3 (GSK3) phosphorylation of CaMKK2 with the anti-mania drug lithium. Furthermore, CaMKK2 null mice representing a loss of function model the human behavioural phenotypes, displaying anxiety and manic-like behavioural disturbances. Our data provide a novel insight into CaMKK2 regulation and its perturbation by a mutation associated with behavioural disorders.
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Yamamoto, Kenta; Wang, Jiguang; Sprinzen, Lisa; Xu, Jun; Haddock, Christopher J; Li, Chen; Lee, Brian J; Loredan, Denis G; Jiang, Wenxia; Vindigni, Alessandro; Wang, Dong; Rabadan, Raul; Zha, Shan
2016-01-01
Missense mutations in ATM kinase, a master regulator of DNA damage responses, are found in many cancers, but their impact on ATM function and implications for cancer therapy are largely unknown. Here we report that 72% of cancer-associated ATM mutations are missense mutations that are enriched around the kinase domain. Expression of kinase-dead ATM (AtmKD/-) is more oncogenic than loss of ATM (Atm-/-) in mouse models, leading to earlier and more frequent lymphomas with Pten deletions. Kinase-dead ATM protein (Atm-KD), but not loss of ATM (Atm-null), prevents replication-dependent removal of Topo-isomerase I-DNA adducts at the step of strand cleavage, leading to severe genomic instability and hypersensitivity to Topo-isomerase I inhibitors. Correspondingly, Topo-isomerase I inhibitors effectively and preferentially eliminate AtmKD/-, but not Atm-proficientor Atm-/- leukemia in animal models. These findings identify ATM kinase-domain missense mutations as a potent oncogenic event and a biomarker for Topo-isomerase I inhibitor based therapy. DOI: http://dx.doi.org/10.7554/eLife.14709.001 PMID:27304073
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Mutations in CSPP1 lead to classical Joubert syndrome.
Akizu, Naiara; Silhavy, Jennifer L; Rosti, Rasim Ozgur; Scott, Eric; Fenstermaker, Ali G; Schroth, Jana; Zaki, Maha S; Sanchez, Henry; Gupta, Neerja; Kabra, Madhulika; Kara, Majdi; Ben-Omran, Tawfeg; Rosti, Basak; Guemez-Gamboa, Alicia; Spencer, Emily; Pan, Roger; Cai, Na; Abdellateef, Mostafa; Gabriel, Stacey; Halbritter, Jan; Hildebrandt, Friedhelm; van Bokhoven, Hans; Gunel, Murat; Gleeson, Joseph G
2014-01-02
Joubert syndrome and related disorders (JSRDs) are genetically heterogeneous and characterized by a distinctive mid-hindbrain malformation. Causative mutations lead to primary cilia dysfunction, which often results in variable involvement of other organs such as the liver, retina, and kidney. We identified predicted null mutations in CSPP1 in six individuals affected by classical JSRDs. CSPP1 encodes a protein localized to centrosomes and spindle poles, as well as to the primary cilium. Despite the known interaction between CSPP1 and nephronophthisis-associated proteins, none of the affected individuals in our cohort presented with kidney disease, and further, screening of a large cohort of individuals with nephronophthisis demonstrated no mutations. CSPP1 is broadly expressed in neural tissue, and its encoded protein localizes to the primary cilium in an in vitro model of human neurogenesis. Here, we show abrogated protein levels and ciliogenesis in affected fibroblasts. Our data thus suggest that CSPP1 is involved in neural-specific functions of primary cilia. Copyright © 2014 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.
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Wang, Bo; Guo, Ruiqi; Zuo, Lei; Shao, Hong; Liu, Ying; Wang, Yu; Ju, Yan; Sun, Chao; Wang, Lifeng; Zhang, Yanmin; Liu, Liwen
2017-08-10
To analyze the phenotype-genotype correlation of MYH7-V878A mutation. Exonic amplification and high-throughput sequencing of 96-cardiovascular disease-related genes were carried out on probands from 210 pedigrees affected with hypertrophic cardiomyopathy (HCM). For the probands, their family members, and 300 healthy volunteers, the identified MYH7-V878A mutation was verified by Sanger sequencing. Information of the HCM patients and their family members, including clinical data, physical examination, echocardiography (UCG), electrocardiography (ECG), and conserved sequence of the mutation among various species were analyzed. A MYH7-V878A mutation was detected in five HCM pedigrees containing 31 family members. Fourteen members have carried the mutation, among whom 11 were diagnosed with HCM, while 3 did not meet the diagnostic criteria. Some of the fourteen members also carried other mutations. Family members not carrying the mutation had normal UCG and ECG. No MYH7-V878A mutation was found among the 300 healthy volunteers. Analysis of sequence conservation showed that the amino acid is located in highly conserved regions among various species. MYH7-V878A is a hot spot among ethnic Han Chinese with a high penetrance. Functional analysis of the conserved sequences suggested that the mutation may cause significant alteration of the function. MYH7-V878A has a significant value for the early diagnosis of HCM.
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Sullivan, Lori S.; Bowne, Sara J.; Koboldt, Daniel C.; Cadena, Elizabeth L.; Heckenlively, John R.; Branham, Kari E.; Wheaton, Dianna H.; Jones, Kaylie D.; Ruiz, Richard S.; Pennesi, Mark E.; Yang, Paul; Davis-Boozer, David; Northrup, Hope; Gurevich, Vsevold V.; Chen, Rui; Xu, Mingchu; Li, Yumei; Birch, David G.; Daiger, Stephen P.
2017-01-01
Purpose To identify the causes of autosomal dominant retinitis pigmentosa (adRP) in a cohort of families without mutations in known adRP genes and consequently to characterize a novel dominant-acting missense mutation in SAG. Methods Patients underwent ophthalmologic testing and were screened for mutations using targeted-capture and whole-exome next-generation sequencing. Confirmation and additional screening were done by Sanger sequencing. Haplotypes segregating with the mutation were determined using short tandem repeat and single nucleotide variant polymorphisms. Genealogies were established by interviews of family members. Results Eight families in a cohort of 300 adRP families, and four additional families, were found to have a novel heterozygous mutation in the SAG gene, c.440G>T; p.Cys147Phe. Patients exhibited symptoms of retinitis pigmentosa and none showed symptoms characteristic of Oguchi disease. All families are of Hispanic descent and most were ascertained in Texas or California. A single haplotype including the SAG mutation was identified in all families. The mutation dramatically alters a conserved amino acid, is extremely rare in global databases, and was not found in 4000+ exomes from Hispanic controls. Molecular modeling based on the crystal structure of bovine arrestin-1 predicts protein misfolding/instability. Conclusions This is the first dominant-acting mutation identified in SAG, a founder mutation possibly originating in Mexico several centuries ago. The phenotype is clearly adRP and is distinct from the previously reported phenotypes of recessive null mutations, that is, Oguchi disease and recessive RP. The mutation accounts for 3% of the 300 families in the adRP Cohort and 36% of Hispanic families in this cohort. PMID:28549094
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Sullivan, Lori S; Bowne, Sara J; Koboldt, Daniel C; Cadena, Elizabeth L; Heckenlively, John R; Branham, Kari E; Wheaton, Dianna H; Jones, Kaylie D; Ruiz, Richard S; Pennesi, Mark E; Yang, Paul; Davis-Boozer, David; Northrup, Hope; Gurevich, Vsevold V; Chen, Rui; Xu, Mingchu; Li, Yumei; Birch, David G; Daiger, Stephen P
2017-05-01
To identify the causes of autosomal dominant retinitis pigmentosa (adRP) in a cohort of families without mutations in known adRP genes and consequently to characterize a novel dominant-acting missense mutation in SAG. Patients underwent ophthalmologic testing and were screened for mutations using targeted-capture and whole-exome next-generation sequencing. Confirmation and additional screening were done by Sanger sequencing. Haplotypes segregating with the mutation were determined using short tandem repeat and single nucleotide variant polymorphisms. Genealogies were established by interviews of family members. Eight families in a cohort of 300 adRP families, and four additional families, were found to have a novel heterozygous mutation in the SAG gene, c.440G>T; p.Cys147Phe. Patients exhibited symptoms of retinitis pigmentosa and none showed symptoms characteristic of Oguchi disease. All families are of Hispanic descent and most were ascertained in Texas or California. A single haplotype including the SAG mutation was identified in all families. The mutation dramatically alters a conserved amino acid, is extremely rare in global databases, and was not found in 4000+ exomes from Hispanic controls. Molecular modeling based on the crystal structure of bovine arrestin-1 predicts protein misfolding/instability. This is the first dominant-acting mutation identified in SAG, a founder mutation possibly originating in Mexico several centuries ago. The phenotype is clearly adRP and is distinct from the previously reported phenotypes of recessive null mutations, that is, Oguchi disease and recessive RP. The mutation accounts for 3% of the 300 families in the adRP Cohort and 36% of Hispanic families in this cohort.
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PTT analysis of polyps from FAP patients reveals a great majority of APC truncating mutations
DOE Office of Scientific and Technical Information (OSTI.GOV)
Luijt, R.B. van der; Khan, P.M.; Tops, C.M.J.
The adenomatous polyposis coli (APC) gene plays an important role in colorectal carcinogenesis. Germline APC mutations are associated with familial adenomatous polyposis (FAP), an autosomal dominantly inherited predisposition to colorectal cancer, characterized by the development of numerous adenomatous polyps in the large intestine. In order to investigate whether somatic inactivation of the remaining APC allele is necessary for adenoma formation, we collected multiple adenomatous polyps from individual FAP patients and investigated the presence of somatic mutations in the APC gene. The analysis of somatic APC mutations in these tumor samples was performed using a rapid and sensitive assay, called themore » protein truncation test (PTT). Chain-terminating somatic APC mutations were detected in the great majority of the tumor samples investigated. As expected, these mutations were mainly located in the mutation cluster region (MCR) in exon 15. Our results confirm that somatic mutation of the second APC allele is required for adenoma formation in FAP. Interestingly, in the polyps investigated in our study, the second APC allele is somatically inactivated through point mutation leading to a stop codon rather than by loss of heterozygosity. The observation that somatic second hits in APC are required for tumor development in FAP is in apparent accordance with the Knudson hypothesis for classical tumor suppressor genes. However, it is yet unknown whether chain-terminating APC mutations lead to a truncated protein exerting a dominant-negative effect or whether these mutations result in a null allele. Further investigation of this important issue will hopefully provide a better understanding of the mechanism of action of the mutated APC alleles in colorectal carcinogenesis.« less
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Clinical significance of somatic mutation in unexplained blood cytopenia
Gallì, Anna; Travaglino, Erica; Ambaglio, Ilaria; Rizzo, Ettore; Molteni, Elisabetta; Elena, Chiara; Ferretti, Virginia Valeria; Catricalà, Silvia; Bono, Elisa; Todisco, Gabriele; Bianchessi, Antonio; Rumi, Elisa; Zibellini, Silvia; Pietra, Daniela; Boveri, Emanuela; Camaschella, Clara; Toniolo, Daniela; Papaemmanuil, Elli; Ogawa, Seishi; Cazzola, Mario
2017-01-01
Unexplained blood cytopenias, in particular anemia, are often found in older persons. The relationship between these cytopenias and myeloid neoplasms like myelodysplastic syndromes is currently poorly defined. We studied a prospective cohort of patients with unexplained cytopenia with the aim to estimate the predictive value of somatic mutations for identifying subjects with, or at risk of, developing a myeloid neoplasm. The study included a learning cohort of 683 consecutive patients investigated for unexplained cytopenia, and a validation cohort of 190 patients referred for suspected myeloid neoplasm. Using granulocyte DNA, we looked for somatic mutations in 40 genes that are recurrently mutated in myeloid malignancies. Overall, 435/683 patients carried a somatic mutation in at least 1 of these genes. Carrying a somatic mutation with a variant allele frequency ≥0.10, or carrying 2 or more mutations, had a positive predictive value for diagnosis of myeloid neoplasm equal to 0.86 and 0.88, respectively. Spliceosome gene mutations and comutation patterns involving TET2, DNMT3A, or ASXL1 had positive predictive values for myeloid neoplasm ranging from 0.86 to 1.0. Within subjects with inconclusive diagnostic findings, carrying 1 or more somatic mutations was associated with a high probability of developing a myeloid neoplasm during follow-up (hazard ratio = 13.9, P < .001). The predictive values of mutation analysis were confirmed in the independent validation cohort. The findings of this study indicate that mutation analysis on peripheral blood granulocytes may significantly improve the current diagnostic approach to unexplained cytopenia and more generally the diagnostic accuracy of myeloid neoplasms. PMID:28424163
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Drosophila Spastin Regulates Synaptic Microtubule Networks and Is Required for Normal Motor Function
Sherwood, Nina Tang; Sun, Qi; Xue, Mingshan; Zhang, Bing
2004-01-01
The most common form of human autosomal dominant hereditary spastic paraplegia (AD-HSP) is caused by mutations in the SPG4 (spastin) gene, which encodes an AAA ATPase closely related in sequence to the microtubule-severing protein Katanin. Patients with AD-HSP exhibit degeneration of the distal regions of the longest axons in the spinal cord. Loss-of-function mutations in the Drosophila spastin gene produce larval neuromuscular junction (NMJ) phenotypes. NMJ synaptic boutons in spastin mutants are more numerous and more clustered than in wild-type, and transmitter release is impaired. spastin-null adult flies have severe movement defects. They do not fly or jump, they climb poorly, and they have short lifespans. spastin hypomorphs have weaker behavioral phenotypes. Overexpression of Spastin erases the muscle microtubule network. This gain-of-function phenotype is consistent with the hypothesis that Spastin has microtubule-severing activity, and implies that spastin loss-of-function mutants should have an increased number of microtubules. Surprisingly, however, we observed the opposite phenotype: in spastin-null mutants, there are fewer microtubule bundles within the NMJ, especially in its distal boutons. The Drosophila NMJ is a glutamatergic synapse that resembles excitatory synapses in the mammalian spinal cord, so the reduction of organized presynaptic microtubules that we observe in spastin mutants may be relevant to an understanding of human Spastin's role in maintenance of axon terminals in the spinal cord. PMID:15562320
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Darzi, Soodabeh; Kiong, Tiong Sieh; Islam, Mohammad Tariqul; Ismail, Mahamod; Kibria, Salehin; Salem, Balasem
2014-01-01
Linear constraint minimum variance (LCMV) is one of the adaptive beamforming techniques that is commonly applied to cancel interfering signals and steer or produce a strong beam to the desired signal through its computed weight vectors. However, weights computed by LCMV usually are not able to form the radiation beam towards the target user precisely and not good enough to reduce the interference by placing null at the interference sources. It is difficult to improve and optimize the LCMV beamforming technique through conventional empirical approach. To provide a solution to this problem, artificial intelligence (AI) technique is explored in order to enhance the LCMV beamforming ability. In this paper, particle swarm optimization (PSO), dynamic mutated artificial immune system (DM-AIS), and gravitational search algorithm (GSA) are incorporated into the existing LCMV technique in order to improve the weights of LCMV. The simulation result demonstrates that received signal to interference and noise ratio (SINR) of target user can be significantly improved by the integration of PSO, DM-AIS, and GSA in LCMV through the suppression of interference in undesired direction. Furthermore, the proposed GSA can be applied as a more effective technique in LCMV beamforming optimization as compared to the PSO technique. The algorithms were implemented using Matlab program.
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Sieh Kiong, Tiong; Tariqul Islam, Mohammad; Ismail, Mahamod; Salem, Balasem
2014-01-01
Linear constraint minimum variance (LCMV) is one of the adaptive beamforming techniques that is commonly applied to cancel interfering signals and steer or produce a strong beam to the desired signal through its computed weight vectors. However, weights computed by LCMV usually are not able to form the radiation beam towards the target user precisely and not good enough to reduce the interference by placing null at the interference sources. It is difficult to improve and optimize the LCMV beamforming technique through conventional empirical approach. To provide a solution to this problem, artificial intelligence (AI) technique is explored in order to enhance the LCMV beamforming ability. In this paper, particle swarm optimization (PSO), dynamic mutated artificial immune system (DM-AIS), and gravitational search algorithm (GSA) are incorporated into the existing LCMV technique in order to improve the weights of LCMV. The simulation result demonstrates that received signal to interference and noise ratio (SINR) of target user can be significantly improved by the integration of PSO, DM-AIS, and GSA in LCMV through the suppression of interference in undesired direction. Furthermore, the proposed GSA can be applied as a more effective technique in LCMV beamforming optimization as compared to the PSO technique. The algorithms were implemented using Matlab program. PMID:25147859
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Guo, Y; Schoell, M C; Freeman, R S
2009-04-23
von Hippel-Lindau (VHL) disease is caused by germ-line mutations in the VHL tumor suppressor gene and is the most common cause of inherited renal cell carcinoma (RCC). Mutations in the VHL gene also occur in a large majority of sporadic cases of clear-cell RCC, which have high intrinsic resistance to chemotherapy and radiotherapy. Here we show that VHL-deficient RCC cells express lower levels of the proapoptotic Bcl-2 family protein BIM(EL) and are more resistant to etoposide and UV radiation-induced death compared to the same cells stably expressing the wild-type VHL protein (pVHL). Reintroducing pVHL into VHL-null cells increased the half-life of BIM(EL) protein without affecting its mRNA expression, and overexpressing pVHL inhibited BIM(EL) polyubiquitination. Suppressing pVHL expression with RNA interference resulted in a decrease in BIM(EL) protein and a corresponding decrease in the sensitivity of RCC cells to apoptotic stimuli. Directly inhibiting BIM(EL) expression in pVHL-expressing RCC cells caused a similar decrease in cell death. These results demonstrate that pVHL acts to promote BIM(EL) protein stability in RCC cells, and that destabilization of BIM(EL) in the absence of pVHL contributes to the increased resistance of VHL-null RCC cells to certain apoptotic stimuli.
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Ito, Akira; Nosrat, Christopher A
2009-09-01
Taste buds and the peripheral nerves innervating them are two important components of the peripheral gustatory system. They require appropriate connections for the taste system to function. Neurotrophic factors play crucial roles in the innervation of peripheral sensory organs and tissues. Both brain-derived neurotrophic factor (BDNF) null-mutated and neurotrophin-4 (NT-4) null-mutated mice exhibit peripheral gustatory deficits. BDNF and NT-4 bind to a common high affinity tyrosine kinase receptor, TrkB (NTRK-2), and a common p75 neurotrophin receptor (NGFR). We are currently using a transgenic mouse model to study peripheral taste system development and innervation in the absence of both TrkB ligands. We show that taste cell progenitors express taste cell markers during early stages of taste bud development in both BDNF(-/-)xNT-4(-/-) and wild-type mice. At early embryonic stages, taste bud progenitors express Troma-1, Shh, and Sox2 in all mice. At later stages, lack of innervation becomes a prominent feature in BDNF(-/-)xNT-4(-/-) mice leading to a decreasing number of fungiform papillae and morphologically degenerating taste cells. A total loss of vallate taste cells also occurs in postnatal transgenic mice. Our data indicate an initial independence but a later permissive and essential role for innervation in taste bud development and maintenance.
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Booker, Fitzgerald; Burkey, Kent; Morgan, Patrick; Fiscus, Edwin; Jones, Alan
2016-01-01
Ozone (O3) uptake by plants leads to an increase in reactive oxygen species (ROS) in the intercellular space of leaves and induces signalling processes reported to involve the membrane-bound heterotrimeric G-protein complex. Therefore, potential G-protein-mediated response mechanisms to O3 were compared between Arabidopsis thaliana L. lines with null mutations in the α- and β-subunits (gpa1-4, agb1-2 and gpa1-4/agb1-2) and Col-0 wild-type plants. Plants were treated with a range of O3 concentrations (5, 125, 175 and 300 nL L−1) for 1 and 2 d in controlled environment chambers. Transcript levels of GPA1, AGB1 and RGS1 transiently increased in Col-0 exposed to 125 nL L−1 O3 compared with the 5 nL L−1 control treatment. However, silencing of α and β G-protein genes resulted in little alteration of many processes associated with O3 injury, including the induction of ROS-signalling genes, increased leaf tissue ion leakage, decreased net photosynthesis and stomatal conductance, and increased peroxidase activity, especially in the leaf apoplast. These results indicated that many responses to O3 stress at physiological levels were not detectably influenced by α and β G-proteins. PMID:21988569
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[Genetic counseling and instruction of marriage for deaf young people: study of 115 cases].
Han, Bing; Dai, Pu; Wang, Guo-Jian; Yuan, Yong-Yi; Li, Qi; Zhang, Xin; Kang, Dong-Yang; Han, Dong-Yi
2009-03-17
To invesigate the molecular pathogenesis of deafness among the youth by means of genetic testing so as to provide pre-marriage genetic counseling and instruction for the deaf youth. 217 deaf young people, 126 males and 91 females, aged 18.9 (16 - 26), from Yunnan and Guizhou provinces, underwent history taking, auditory testing, and collection of peripheral blood samples. Genomic DNA and mitochondrial DNA were extracted to undergo sequence analysis of the entire gene GJB2, common point mutation of SLC26A4 gene, and mutation of mtDNA A1555G. Genetic prediction and marriage instruction were provided to each subject based on these results. Twenty-three of the 117 persons (10.5%), 13 males and 10 females, were mtDNA A1555G mutation carriers and they were instructed that they, their maternal relatives, and the offspring of the female carriers, should they be born, should strictly avoid the administration of amino glycoside antibiotics. Twenty eight of the 115 persons (12.9%), were confirmed to carry homozygous or compound GJB2 mutations, 5 individuals (2.3%) carried heterozygous GJB2 mutation, 19 (8.8%) carried homozygous or compound SLC26A4 mutations, and one (0.5%) carried heterozygous SLC26A4 mutation. The suggestion for them was to avoid getting married with deaf partners caused by the same deaf gene or with individuals carrying mutations in the same deaf gene. Meanwhile, suggestions such as avoiding aggressive exercises and head injury were provided to the deaf young people with SLC26A4 mutations. Genetic testing can provide more accurate and useful genetic counseling and instruction to deaf young people for their partner selection and eugenics.
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Peachey, Neal S; Hasan, Nazarul; FitzMaurice, Bernard; Burrill, Samantha; Pangeni, Gobinda; Karst, Son Yong; Reinholdt, Laura; Berry, Melissa L; Strobel, Marge; Gregg, Ronald G; McCall, Maureen A; Chang, Bo
2017-08-01
GRM6 encodes the metabotropic glutamate receptor 6 (mGluR6) used by retinal depolarizing bipolar cells (DBCs). Mutations in GRM6 lead to DBC dysfunction and underlie the human condition autosomal recessive complete congenital stationary night blindness. Mouse mutants for Grm6 are important models for this condition. Here we report a new Grm6 mutant, identified in an electroretinogram (ERG) screen of mice maintained at The Jackson Laboratory. The Grm6 nob8 mouse has a reduced-amplitude b-wave component of the ERG, which reflects light-evoked DBC activity. Sequencing identified a missense mutation that converts a highly conserved methionine within the ligand binding domain to leucine (p.Met66Leu). Consistent with prior studies of Grm6 mutant mice, the laminar size and structure in the Grm6 nob8 retina were comparable to control. The Grm6 nob8 phenotype is distinguished from other Grm6 mutants that carry a null allele by a reduced but not absent ERG b-wave, decreased but present expression of mGluR6 at DBC dendritic tips, and mislocalization of mGluR6 to DBC somas. Consistent with a reduced but not absent b-wave, there were a subset of retinal ganglion cells whose responses to light onset have times to peak within the range of those in control retinas. These data indicate that the p.Met66Leu mutant mGluR6 is trafficked less than control. However, the mGluR6 that is localized to the DBC dendritic tips is able to initiate DBC signal transduction. The Grm6 nob8 mouse extends the Grm6 allelic series and will be useful for elucidating the role of mGluR6 in DBC signal transduction and in human disease. NEW & NOTEWORTHY This article describes a mouse model of the human disease complete congenital stationary night blindness in which the mutation reduces but does not eliminate GRM6 expression and bipolar cell function, a distinct phenotype from that seen in other Grm6 mouse models.
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Shin, Jimann; Padmanabhan, Arun; de Groh, Eric D.; Lee, Jeong-Soo; Haidar, Sam; Dahlberg, Suzanne; Guo, Feng; He, Shuning; Wolman, Marc A.; Granato, Michael; Lawson, Nathan D.; Wolfe, Scot A.; Kim, Seok-Hyung; Solnica-Krezel, Lilianna; Kanki, John P.; Ligon, Keith L.; Epstein, Jonathan A.; Look, A. Thomas
2012-01-01
SUMMARY Neurofibromatosis type 1 (NF1) is a common, dominantly inherited genetic disorder that results from mutations in the neurofibromin 1 (NF1) gene. Affected individuals demonstrate abnormalities in neural-crest-derived tissues that include hyperpigmented skin lesions and benign peripheral nerve sheath tumors. NF1 patients also have a predisposition to malignancies including juvenile myelomonocytic leukemia (JMML), optic glioma, glioblastoma, schwannoma and malignant peripheral nerve sheath tumors (MPNSTs). In an effort to better define the molecular and cellular determinants of NF1 disease pathogenesis in vivo, we employed targeted mutagenesis strategies to generate zebrafish harboring stable germline mutations in nf1a and nf1b, orthologues of NF1. Animals homozygous for loss-of-function alleles of nf1a or nf1b alone are phenotypically normal and viable. Homozygous loss of both alleles in combination generates larval phenotypes that resemble aspects of the human disease and results in larval lethality between 7 and 10 days post fertilization. nf1-null larvae demonstrate significant central and peripheral nervous system defects. These include aberrant proliferation and differentiation of oligodendrocyte progenitor cells (OPCs), dysmorphic myelin sheaths and hyperplasia of Schwann cells. Loss of nf1 contributes to tumorigenesis as demonstrated by an accelerated onset and increased penetrance of high-grade gliomas and MPNSTs in adult nf1a+/−; nf1b−/−; p53e7/e7 animals. nf1-null larvae also demonstrate significant motor and learning defects. Importantly, we identify and quantitatively analyze a novel melanophore phenotype in nf1-null larvae, providing the first animal model of the pathognomonic pigmentation lesions of NF1. Together, these findings support a role for nf1a and nf1b as potent tumor suppressor genes that also function in the development of both central and peripheral glial cells as well as melanophores in zebrafish. PMID:22773753
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The Dictyostelium discoideum RACK1 orthologue has roles in growth and development
2014-01-01
Background The receptor for activated C-kinase 1 (RACK1) is a conserved protein belonging to the WD40 repeat family of proteins. It folds into a beta propeller with seven blades which allow interactions with many proteins. Thus it can serve as a scaffolding protein and have roles in several cellular processes. Results We identified the product of the Dictyostelium discoideum gpbB gene as the Dictyostelium RACK1 homolog. The protein is mainly cytosolic but can also associate with cellular membranes. DdRACK1 binds to phosphoinositides (PIPs) in protein-lipid overlay and liposome-binding assays. The basis of this activity resides in a basic region located in the extended loop between blades 6 and 7 as revealed by mutational analysis. Similar to RACK1 proteins from other organisms DdRACK1 interacts with G protein subunits alpha, beta and gamma as shown by yeast two-hybrid, pulldown, and immunoprecipitation assays. Unlike the Saccharomyces cerevisiae and Cryptococcus neoformans RACK1 proteins it does not appear to take over Gβ function in D. discoideum as developmental and other defects were not rescued in Gβ null mutants overexpressing GFP-DdRACK1. Overexpression of GFP-tagged DdRACK1 and a mutant version (DdRACK1mut) which carried a charge-reversal mutation in the basic region in wild type cells led to changes during growth and development. Conclusion DdRACK1 interacts with heterotrimeric G proteins and can through these interactions impact on processes specifically regulated by these proteins. PMID:24930026
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Toki, Hideaki; Minowa, Osamu; Inoue, Maki
Dominant mutations in the Serca2 gene, which encodes sarco(endo)plasmic reticulum calcium-ATPase, predispose mice to gastrointestinal epithelial carcinoma [1–4] and humans to Darier disease (DD) [14–17]. In this study, we generated mice harboring N-ethyl-N-nitrosourea (ENU)-induced allelic mutations in Serca2: three missense mutations and one nonsense mutation. Mice harboring these Serca2 mutations developed tumors that were categorized as either early onset squamous cell tumors (SCT), with development similar to null-type knockout mice [2,4] (aggressive form; M682, M814), or late onset tumors (mild form; M1049, M1162). Molecular analysis showed no aberration in Serca2 mRNA or protein expression levels in normal esophageal cells ofmore » any of the four mutant heterozygotes. There was no loss of heterozygosity at the Serca2 locus in the squamous cell carcinomas in any of the four lines. The effect of each mutation on Ca{sup 2+}-ATPase activity was predicted using atomic-structure models and accumulated mutated protein studies, suggesting that putative complete loss of Serca2 enzymatic activity may lead to early tumor onset, whereas mutations in which Serca2 retains residual enzymatic activity result in late onset. We propose that impaired Serca2 gene product activity has a long-term effect on squamous cell carcinogenesis from onset to the final carcinoma stage through an as-yet unrecognized but common regulatory pathway. -- Highlights: •Novel mutations in murine Serca2 caused early onset or late onset of tumorigenesis. •They also caused higher or lower incidence of Darier Disease phenotype. •3D structure model suggested the former mutations led to severer defect on ATPase. •Driver gene mutations via long-range effect on Ca2+ distributions are suggested.« less
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Clinical and molecular phenotype of Aicardi-Goutieres syndrome.
Rice, Gillian; Patrick, Teresa; Parmar, Rekha; Taylor, Claire F; Aeby, Alec; Aicardi, Jean; Artuch, Rafael; Montalto, Simon Attard; Bacino, Carlos A; Barroso, Bruno; Baxter, Peter; Benko, Willam S; Bergmann, Carsten; Bertini, Enrico; Biancheri, Roberta; Blair, Edward M; Blau, Nenad; Bonthron, David T; Briggs, Tracy; Brueton, Louise A; Brunner, Han G; Burke, Christopher J; Carr, Ian M; Carvalho, Daniel R; Chandler, Kate E; Christen, Hans-Jurgen; Corry, Peter C; Cowan, Frances M; Cox, Helen; D'Arrigo, Stefano; Dean, John; De Laet, Corinne; De Praeter, Claudine; Dery, Catherine; Ferrie, Colin D; Flintoff, Kim; Frints, Suzanna G M; Garcia-Cazorla, Angels; Gener, Blanca; Goizet, Cyril; Goutieres, Francoise; Green, Andrew J; Guet, Agnes; Hamel, Ben C J; Hayward, Bruce E; Heiberg, Arvid; Hennekam, Raoul C; Husson, Marie; Jackson, Andrew P; Jayatunga, Rasieka; Jiang, Yong-Hui; Kant, Sarina G; Kao, Amy; King, Mary D; Kingston, Helen M; Klepper, Joerg; van der Knaap, Marjo S; Kornberg, Andrew J; Kotzot, Dieter; Kratzer, Wilfried; Lacombe, Didier; Lagae, Lieven; Landrieu, Pierre Georges; Lanzi, Giovanni; Leitch, Andrea; Lim, Ming J; Livingston, John H; Lourenco, Charles M; Lyall, E G Hermione; Lynch, Sally A; Lyons, Michael J; Marom, Daphna; McClure, John P; McWilliam, Robert; Melancon, Serge B; Mewasingh, Leena D; Moutard, Marie-Laure; Nischal, Ken K; Ostergaard, John R; Prendiville, Julie; Rasmussen, Magnhild; Rogers, R Curtis; Roland, Dominique; Rosser, Elisabeth M; Rostasy, Kevin; Roubertie, Agathe; Sanchis, Amparo; Schiffmann, Raphael; Scholl-Burgi, Sabine; Seal, Sunita; Shalev, Stavit A; Corcoles, C Sierra; Sinha, Gyan P; Soler, Doriette; Spiegel, Ronen; Stephenson, John B P; Tacke, Uta; Tan, Tiong Yang; Till, Marianne; Tolmie, John L; Tomlin, Pam; Vagnarelli, Federica; Valente, Enza Maria; Van Coster, Rudy N A; Van der Aa, Nathalie; Vanderver, Adeline; Vles, Johannes S H; Voit, Thomas; Wassmer, Evangeline; Weschke, Bernhard; Whiteford, Margo L; Willemsen, Michel A A; Zankl, Andreas; Zuberi, Sameer M; Orcesi, Simona; Fazzi, Elisa; Lebon, Pierre; Crow, Yanick J
2007-10-01
Aicardi-Goutieres syndrome (AGS) is a genetic encephalopathy whose clinical features mimic those of acquired in utero viral infection. AGS exhibits locus heterogeneity, with mutations identified in genes encoding the 3'-->5' exonuclease TREX1 and the three subunits of the RNASEH2 endonuclease complex. To define the molecular spectrum of AGS, we performed mutation screening in patients, from 127 pedigrees, with a clinical diagnosis of the disease. Biallelic mutations in TREX1, RNASEH2A, RNASEH2B, and RNASEH2C were observed in 31, 3, 47, and 18 families, respectively. In five families, we identified an RNASEH2A or RNASEH2B mutation on one allele only. In one child, the disease occurred because of a de novo heterozygous TREX1 mutation. In 22 families, no mutations were found. Null mutations were common in TREX1, although a specific missense mutation was observed frequently in patients from northern Europe. Almost all mutations in RNASEH2A, RNASEH2B, and RNASEH2C were missense. We identified an RNASEH2C founder mutation in 13 Pakistani families. We also collected clinical data from 123 mutation-positive patients. Two clinical presentations could be delineated: an early-onset neonatal form, highly reminiscent of congenital infection seen particularly with TREX1 mutations, and a later-onset presentation, sometimes occurring after several months of normal development and occasionally associated with remarkably preserved neurological function, most frequently due to RNASEH2B mutations. Mortality was correlated with genotype; 34.3% of patients with TREX1, RNASEH2A, and RNASEH2C mutations versus 8.0% RNASEH2B mutation-positive patients were known to have died (P=.001). Our analysis defines the phenotypic spectrum of AGS and suggests a coherent mutation-screening strategy in this heterogeneous disorder. Additionally, our data indicate that at least one further AGS-causing gene remains to be identified.
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Prajapati, Chandra; Pölönen, Risto-Pekka; Rajala, Kristiina; Pekkanen-Mattila, Mari; Rasku, Jyrki; Larsson, Kim; Aalto-Setälä, Katriina
2016-01-01
Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disease, which affects the structure of heart muscle tissue. The clinical symptoms include arrhythmias, progressive heart failure, and even sudden cardiac death but the mutation carrier can also be totally asymptomatic. To date, over 1400 mutations have been linked to HCM, mostly in genes encoding for sarcomeric proteins. However, the pathophysiological mechanisms of the disease are still largely unknown. Two founder mutations for HCM in Finland are located in myosin-binding protein C (MYBPC3-Gln1061X) and α-tropomyosin (TPM1-Asp175Asn) genes. We studied the properties of HCM cardiomyocytes (CMs) derived from patient-specific human induced pluripotent stem cells (hiPSCs) carrying either MYBPC3-Gln1061X or TPM1-Asp175Asn mutation. Both types of HCM-CMs displayed pathological phenotype of HCM but, more importantly, we found differences between CMs carrying either MYBPC3-Gln1061X or TPM1-Asp175Asn gene mutation in their cellular size, Ca2+ handling, and electrophysiological properties, as well as their gene expression profiles. These findings suggest that even though the clinical phenotypes of the patients carrying either MYBPC3-Gln1061X or TPM1-Asp175Asn gene mutation are similar, the genetic background as well as the functional properties on the cellular level might be different, indicating that the pathophysiological mechanisms behind the two mutations would be divergent as well. PMID:27057166
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Broncy, Lucile; Njima, Basma Ben; Méjean, Arnaud; Béroud, Christophe; Romdhane, Khaled Ben; Ilie, Marius; Hofman, Veronique; Muret, Jane; Hofman, Paul; Bouhamed, Habiba Chaabouni; Paterlini-Bréchot, And Patrizia
2018-04-13
Circulating Rare Cells (CRC) are non-haematological cells circulating in blood. They include Circulating Cancer Cells (CCC) and cells with uncertain malignant features (CRC-UMF) according to cytomorphology. Clear cell renal cell carcinomas frequently bear a mutated Von Hippel-Lindau (VHL) gene. To match blind genetic analysis of CRC and tumor samples with CRC cytopathological diagnosis. 29/30 patients harboured CRC (20 harboured CCC, 29 CRC-UMF) and 25/29 patients carried VHL mutations in their tumour. 205 single CRC (64 CCC, 141 CRC-UMF) provided genetic data. 57/57 CCC and 104/125 CRC-UMF from the 25 patients with VHL-mutated tumor carried the same VHL mutation detected in the tumor. Seven CCC and 16 CRC-UMF did not carry VHL mutations but were found in patients with wild-type VHL tumor tissue. All the CCC and 83,2% (104/125) of the CRC-UMF were found to carry the same VHL mutation identified in the corresponding tumorous tissue, validating cytopathological identification of CCC in patients with clear cell renal cell carcinoma. The blood of 30 patients with clear cell renal cell carcinoma was treated by ISET ® for CRC isolation, cytopathology and single-cell VHL mutations analysis, performed blindly and compared to VHL mutations of corresponding tumor tissues and leukocytes.
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Disrupting the male germ line to find infertility and contraception targets.
Archambeault, Denise R; Matzuk, Martin M
2014-05-01
Genetically-manipulated mouse models have become indispensible for broadening our understanding of genes and pathways related to male germ cell development. Until suitable in vitro systems for studying spermatogenesis are perfected, in vivo models will remain the gold standard for inquiry into testicular function. Here, we discuss exciting advances that are allowing researchers faster, easier, and more customizable access to their mouse models of interest. Specifically, the trans-NIH Knockout Mouse Project (KOMP) is working to generate knockout mouse models of every gene in the mouse genome. The related Knockout Mouse Phenotyping Program (KOMP2) is performing systematic phenotypic analysis of this genome-wide collection of knockout mice, including fertility screening. Together, these programs will not only uncover new genes involved in male germ cell development but also provide the research community with the mouse models necessary for further investigations. In addition to KOMP/KOMP2, another promising development in the field of mouse models is the advent of CRISPR (clustered regularly interspaced short palindromic repeat)-Cas technology. Utilizing 20 nucleotide guide sequences, CRISPR/Cas has the potential to introduce sequence-specific insertions, deletions, and point mutations to produce null, conditional, activated, or reporter-tagged alleles. CRISPR/Cas can also successfully target multiple genes in a single experimental step, forgoing the multiple generations of breeding traditionally required to produce mouse models with deletions, insertions, or mutations in multiple genes. In addition, CRISPR/Cas can be used to create mouse models carrying variants identical to those identified in infertile human patients, providing the opportunity to explore the effects of such mutations in an in vivo system. Both the KOMP/KOMP2 projects and the CRISPR/Cas system provide powerful, accessible genetic approaches to the study of male germ cell development in the mouse. A more complete understanding of male germ cell biology is critical for the identification of novel targets for potential non-hormonal contraceptive intervention. Copyright © 2014. Published by Elsevier Masson SAS.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Hoekstra, M.F.; Ou, A.C.; DeMaggio, A.J.
In simple eukaryotes, protein kinases regulate mitotic and meiotic cell cycles, the response to polypeptide pheromones, and the initiation of nuclear DNA synthesis. The protein HRR25 from the budding yeast Saccharomyces cerevisiae was defined by the mutation hrr25-1. This mutation resulted in sensitivity to continuous expression of the HO double-strand endonuclease, to methyl methanesulfonate, and to x-irradiation. Homozygotes of hrr25-1 were unable to sporulate and disruption and deletion of HRR25 interfered with mitotic and meiotic cell division. Sequence analysis revealed two distinctive regions in the protein. The NH{sub 2}-terminus of HRR25 contains the hallmark features of protein kinases, whereas themore » COOH-terminus is rich in proline and glutamine. Mutations in HRR25 at conserved residues found in all protein kinases inactivated the gene, and these mutants exhibited the hrr25 null phenotypes. Taken together, the hrr25 mutant phenotypes and the features of the gene product indicate that HRR25 is a distinctive member of the protein kinase superfamily.« less
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The role of weak selection and high mutation rates in nearly neutral evolution.
Lawson, Daniel John; Jensen, Henrik Jeldtoft
2009-04-21
Neutral dynamics occur in evolution if all types are 'effectively equal' in their reproductive success, where the definition of 'effectively equal' depends on the population size and the details of mutations. Empirically observed neutral genetic evolution in extremely large clonal populations can only be explained under current models if selection is completely absent. Such models typically consider the case where population dynamics occurs on a different timescale to evolution. However, this assumption is invalid when mutations are not rare in a whole population. We show that this has important consequences for the occurrence of neutral evolution in clonal populations. In highly connected type spaces, neutral dynamics can occur for all population sizes despite significant selective differences, via the forming of effectively neutral networks connecting rare neutral types. Biological implications include an explanation for the high diversity of rare types that survive in large clonal populations, and a theoretical justification for the use of neutral null models.
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Lee, S; Parent, C A; Insall, R; Firtel, R A
1999-09-01
We have identified a novel Ras-interacting protein from Dictyostelium, RIP3, whose function is required for both chemotaxis and the synthesis and relay of the cyclic AMP (cAMP) chemoattractant signal. rip3 null cells are unable to aggregate and lack receptor activation of adenylyl cyclase but are able, in response to cAMP, to induce aggregation-stage, postaggregative, and cell-type-specific gene expression in suspension culture. In addition, rip3 null cells are unable to properly polarize in a cAMP gradient and chemotaxis is highly impaired. We demonstrate that cAMP stimulation of guanylyl cyclase, which is required for chemotaxis, is reduced approximately 60% in rip3 null cells. This reduced activation of guanylyl cyclase may account, in part, for the defect in chemotaxis. When cells are pulsed with cAMP for 5 h to mimic the endogenous cAMP oscillations that occur in wild-type strains, the cells will form aggregates, most of which, however, arrest at the mound stage. Unlike the response seen in wild-type strains, the rip3 null cell aggregates that form under these experimental conditions are very small, which is probably due to the rip3 null cell chemotaxis defect. Many of the phenotypes of the rip3 null cell, including the inability to activate adenylyl cyclase in response to cAMP and defects in chemotaxis, are very similar to those of strains carrying a disruption of the gene encoding the putative Ras exchange factor AleA. We demonstrate that aleA null cells also exhibit a defect in cAMP-mediated activation of guanylyl cyclase similar to that of rip3 null cells. A double-knockout mutant (rip3/aleA null cells) exhibits a further reduction in receptor activation of guanylyl cyclase, and these cells display almost no cell polarization or movement in cAMP gradients. As RIP3 preferentially interacts with an activated form of the Dictyostelium Ras protein RasG, which itself is important for cell movement, we propose that RIP3 and AleA are components of a Ras-regulated pathway involved in integrating chemotaxis and signal relay pathways that are essential for aggregation.
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Ammar-Khodja, Fatima; Faugère, Valérie; Baux, David; Giannesini, Claire; Léonard, Susana; Makrelouf, Mohamed; Malek, Rahia; Djennaoui, Djamel; Zenati, Akila; Claustres, Mireille; Roux, Anne-Françoise
2009-01-01
A systematic approach, involving haplotyping and genotyping, to the molecular diagnosis of non-syndromic deafness within 50 families and 9 sporadic cases from Algeria is described. Mutations at the DFNB1 locus (encompassing the GJB2 and GJB6 genes) are responsible for more than half of autosomal recessive prelingual non-syndromic deafness in various populations. A c.35delG mutation can account for up to 85% of GJB2 mutations and two large deletions del(GJB6-D13S1830) and del(GJB6-D13S1854) have also been reported in several population groups. In view of the genetic heterogeneity a strategy was developed which involved direct analysis of DFNB1. In negative familial cases, haplotype analysis was carried out, where possible, to exclude DFNB1 mutations. Following this, haplotype analysis of five Usher syndrome loci, sometimes involved in autosomal non-syndromic hearing loss, was carried out to identify cases in which Usher gene sequencing was indicated. When homozygosity was observed at a locus in a consanguineous family, the corresponding gene was exhaustively sequenced. Pathogenic DFNB1 genotypes were identified in 40% of the cases. Of the 21 cases identified with 2 pathogenic mutations, c.35delG represented 76% of the mutated alleles. The additional mutations were one nonsense, two missense and one splicing mutation. Four additional patients were identified with a single DFNB1 mutation. None carried the large deletions. Three families with non-syndromic deafness carried novel unclassified variants (UVs) in MYO7A (1 family) and CDH23 (2 families) of unknown pathogenic effect. Additionally, molecular diagnosis was carried out on two Usher type I families and pathogenic mutations in MYO7A and PCDH15 were found.
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The Leishmania major BBSome subunit BBS1 is essential for parasite virulence in the mammalian host
Price, Helen P; Paape, Daniel; Hodgkinson, Michael R; Farrant, Katie; Doehl, Johannes; Stark, Meg; Smith, Deborah F
2013-01-01
Summary Bardet–Biedl syndrome (BBS) is a human genetic disorder with a spectrum of symptoms caused by primary cilium dysfunction. The disease is caused by mutations in one of at least 17 identified genes, of which seven encode subunits of the BBSome, a protein complex required for specific trafficking events to and from the primary cilium. The molecular mechanisms associated with BBSome function remain to be fully elucidated. Here, we generated null and complemented mutants of the BBSome subunit BBS1 in the protozoan parasite, Leishmania. In the absence of BBS1, extracellular parasites have no apparent defects in growth, flagellum assembly, motility or differentiation in vitro but there is accumulation of vacuole-like structures close to the flagellar pocket. Infectivity of these parasites for macrophages in vitro is reduced compared with wild-type controls but the null parasites retain the ability to differentiate to the intracellular amastigote stage. However, infectivity of BBS1 null parasites is severely compromised in a BALB/c mouse footpad model. We hypothesize that the absence of BBS1 in Leishmania leads to defects in specific trafficking events that affect parasite persistence in the host. This is the first report of an association between the BBSome complex and pathogen infectivity. PMID:23998526
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Glutamate Dehydrogenase Affects Resistance to Cell Wall Antibiotics in Bacillus subtilis
Lee, Yong Heon; Kingston, Anthony W.
2012-01-01
The glutamate dehydrogenase RocG of Bacillus subtilis is a bifunctional protein with both enzymatic and regulatory functions. Here we show that the rocG null mutant is sensitive to β-lactams, including cefuroxime (CEF), and to fosfomycin but that resistant mutants arise due to gain-of-function mutations in gudB, which encodes an otherwise inactive glutamate dehydrogenase. In the presence of CEF, ΔrocG ΔgudB mutant cells exhibit growth arrest when they reach mid-exponential phase. Using microarray-based transcriptional profiling, we found that the σW regulon was downregulated in the ΔrocG ΔgudB null mutant. A survey of σW-controlled genes for effects on CEF resistance identified both the NfeD protein YuaF and the flotillin homologue YuaG (FloT). Notably, overexpression of yuaFG in the rocG null mutant prevents the growth arrest induced by CEF. The YuaG flotillin has been shown previously to localize to defined lipid microdomains, and we show here that the yuaFGI operon contributes to a σW-dependent decrease in membrane fluidity. We conclude that glutamate dehydrogenase activity affects the expression of the σW regulon, by pathways that are yet unclear, and thereby influences resistance to CEF and other antibiotics. PMID:22178969
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Glutamate dehydrogenase affects resistance to cell wall antibiotics in Bacillus subtilis.
Lee, Yong Heon; Kingston, Anthony W; Helmann, John D
2012-03-01
The glutamate dehydrogenase RocG of Bacillus subtilis is a bifunctional protein with both enzymatic and regulatory functions. Here we show that the rocG null mutant is sensitive to β-lactams, including cefuroxime (CEF), and to fosfomycin but that resistant mutants arise due to gain-of-function mutations in gudB, which encodes an otherwise inactive glutamate dehydrogenase. In the presence of CEF, ΔrocG ΔgudB mutant cells exhibit growth arrest when they reach mid-exponential phase. Using microarray-based transcriptional profiling, we found that the σ(W) regulon was downregulated in the ΔrocG ΔgudB null mutant. A survey of σ(W)-controlled genes for effects on CEF resistance identified both the NfeD protein YuaF and the flotillin homologue YuaG (FloT). Notably, overexpression of yuaFG in the rocG null mutant prevents the growth arrest induced by CEF. The YuaG flotillin has been shown previously to localize to defined lipid microdomains, and we show here that the yuaFGI operon contributes to a σ(W)-dependent decrease in membrane fluidity. We conclude that glutamate dehydrogenase activity affects the expression of the σ(W) regulon, by pathways that are yet unclear, and thereby influences resistance to CEF and other antibiotics.
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Hara, Munetsugu; Takahashi, Tomoyuki; Mitsumasu, Chiaki; Igata, Sachiyo; Takano, Makoto; Minami, Tomoko; Yasukawa, Hideo; Okayama, Satoko; Nakamura, Keiichiro; Okabe, Yasunori; Tanaka, Eiichiro; Takemura, Genzou; Kosai, Ken-ichiro; Yamashita, Yushiro; Matsuishi, Toyojiro
2015-01-01
Methyl-CpG-binding protein 2 (MeCP2) is an epigenetic regulator of gene expression that is essential for normal brain development. Mutations in MeCP2 lead to disrupted neuronal function and can cause Rett syndrome (RTT), a neurodevelopmental disorder. Previous studies reported cardiac dysfunction, including arrhythmias in both RTT patients and animal models of RTT. In addition, recent studies indicate that MeCP2 may be involved in cardiac development and dysfunction, but its role in the developing and adult heart remains unknown. In this study, we found that Mecp2-null ESCs could differentiate into cardiomyocytes, but the development and further differentiation of cardiovascular progenitors were significantly affected in MeCP2 deficiency. In addition, we revealed that loss of MeCP2 led to dysregulation of endogenous cardiac genes and myocardial structural alterations, although Mecp2-null mice did not exhibit obvious cardiac functional abnormalities. Furthermore, we detected methylation of the CpG islands in the Tbx5 locus, and showed that MeCP2 could target these sequences. Taken together, these results suggest that MeCP2 is an important regulator of the gene-expression program responsible for maintaining normal cardiac development and cardiomyocyte structure. PMID:26073556
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Tarin, Carlos; Lavin, Begoña; Gomez, Monica; Saura, Marta; Diez-Juan, Antonio; Zaragoza, Carlos
2011-07-15
Nitric oxide (NO) is an important defense against myocardial ischemia/reperfusion (I/R) injury. Although matrix metalloproteinase (MMP)-mediated necrosis of cardiac myocytes is well characterized, the role of inducible NO synthase (iNOS)-derived NO in this process is poorly understood. I/R injury was increased in iNOS-deficient mice and in mice treated with 1400 W (a pharmacological iNOS inhibitor) and was associated with significantly increased expression of extracellular matrix metalloproteinase inducer (EMMPRIN) and EMMPRIN-associated MMPs. Transcriptional activity of an EMMPRIN luciferase promoter reporter expressed in cardiac myocytes was inhibited by NO in a cGMP-dependent manner, and this transcriptional inhibition was abolished by mutation of a putative E2F site. Consistent with these findings, EMMPRIN null mice, in which iNOS is normally induced, are partially protected against I/R injury. Pharmacological inhibition of iNOS in EMMPRIN null mice had no additional protective effect, suggesting that EMMPRIN is a downstream target of NO. Administration of anti-EMMPRIN neutralizing antibodies partly reduced the excess heart damage and MMP-9 expression induced by I/R in iNOS null mice, indicating that regulation of EMMPRIN is an important mechanism of NO-mediated cardioprotection. Copyright © 2011 Elsevier Inc. All rights reserved.
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Fascin1-Dependent Filopodia are Required for Directional Migration of a Subset of Neural Crest Cells
Boer, Elena F.; Howell, Elizabeth D.; Schilling, Thomas F.; Jette, Cicely A.; Stewart, Rodney A.
2015-01-01
Directional migration of neural crest (NC) cells is essential for patterning the vertebrate embryo, including the craniofacial skeleton. Extensive filopodial protrusions in NC cells are thought to sense chemo-attractive/repulsive signals that provide directionality. To test this hypothesis, we generated null mutations in zebrafish fascin1a (fscn1a), which encodes an actin-bundling protein required for filopodia formation. Homozygous fscn1a zygotic null mutants have normal NC filopodia due to unexpected stability of maternal Fscn1a protein throughout NC development and into juvenile stages. In contrast, maternal/zygotic fscn1a null mutant embryos (fscn1a MZ) have severe loss of NC filopodia. However, only a subset of NC streams display migration defects, associated with selective loss of craniofacial elements and peripheral neurons. We also show that fscn1a-dependent NC migration functions through cxcr4a/cxcl12b chemokine signaling to ensure the fidelity of directional cell migration. These data show that fscn1a-dependent filopodia are required in a subset of NC cells to promote cell migration and NC derivative formation, and that perdurance of long-lived maternal proteins can mask essential zygotic gene functions during NC development. PMID:25607881
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A knock-in mouse line conditionally expressing the tumor suppressor WTX/AMER1.
Boutet, Agnès; Comai, Glenda; Charlet, Aurélie; Jian Motamedi, Fariba; Dhib, Haroun; Bandiera, Roberto; Schedl, Andreas
2017-11-01
WTX/AMER1 is an important developmental regulator, mutations in which have been identified in a proportion of patients suffering from the renal neoplasm Wilms' tumor and in the bone malformation syndrome Osteopathia Striata with Cranial Sclerosis (OSCS). Its cellular functions appear complex and the protein can be found at the membrane, within the cytoplasm and the nucleus. To understand its developmental and cellular function an allelic series for Wtx in the mouse is crucial. Whereas mice carrying a conditional knock out allele for Wtx have been previously reported, a gain-of-function mouse model that would allow studying the molecular, cellular and developmental role of Wtx is still missing. Here we describe the generation of a novel mouse strain that permits the conditional activation of WTX expression. Wtx fused to GFP was introduced downstream a stop cassette flanked by loxP sites into the Rosa26 locus by gene targeting. Ectopic WTX expression is reported after crosses with several Cre transgenic mice in different embryonic tissues. Further, functionality of the fusion protein was demonstrated in the context of a Wtx null allele. © 2017 Wiley Periodicals, Inc.
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Effects of exercise on circadian rhythms and mobility in aging Drosophila melanogaster.
Rakshit, Kuntol; Wambua, Rebecca; Giebultowicz, Tomasz M; Giebultowicz, Jadwiga M
2013-11-01
Daily life functions such as sleep and feeding oscillate with circa 24 h period due to endogenous circadian rhythms generated by circadian clocks. Genetic or environmental disruption of circadian rhythms is associated with various aging-related phenotypes. Circadian rhythms decay during normal aging, and there is a need to explore strategies that could avert age-related changes in the circadian system. Exercise was reported to delay aging in mammals. Here, we investigated whether daily exercise via stimulation of upward climbing movement could improve circadian rest/activity rhythms in aging Drosophila melanogaster. We found that repeated exercise regimen did not strengthen circadian locomotor activity rhythms in aging flies and had no effect on their lifespan. We also tested the effects of exercise on mobility and determined that regular exercise lowered age-specific climbing ability in both wild type and clock mutant flies. Interestingly, the climbing ability was most significantly reduced in flies carrying a null mutation in the core clock gene period, while rescue of this gene significantly improved climbing to wild type levels. Our work highlights the importance of period in sustaining endurance in aging flies exposed to physical challenge. © 2013.
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Clinical and Molecular Phenotype of Aicardi-Goutières Syndrome
Rice, Gillian ; Patrick, Teresa ; Parmar, Rekha ; Taylor, Claire F. ; Aeby, Alec ; Aicardi, Jean ; Artuch, Rafael ; Montalto, Simon Attard ; Bacino, Carlos A. ; Barroso, Bruno ; Baxter, Peter ; Benko, Willam S. ; Bergmann, Carsten ; Bertini, Enrico ; Biancheri, Roberta ; Blair, Edward M. ; Blau, Nenad ; Bonthron, David T. ; Briggs, Tracy ; Brueton, Louise A. ; Brunner, Han G. ; Burke, Christopher J. ; Carr, Ian M. ; Carvalho, Daniel R. ; Chandler, Kate E. ; Christen, Hans-Jürgen ; Corry, Peter C. ; Cowan, Frances M. ; Cox, Helen ; D’Arrigo, Stefano ; Dean, John ; De Laet, Corinne ; De Praeter, Claudine ; Déry, Catherine ; Ferrie, Colin D. ; Flintoff, Kim ; Frints, Suzanna G. M. ; Garcia-Cazorla, Angels ; Gener, Blanca ; Goizet, Cyril ; Goutières, Françoise ; Green, Andrew J. ; Guët, Agnès ; Hamel, Ben C. J. ; Hayward, Bruce E. ; Heiberg, Arvid ; Hennekam, Raoul C. ; Husson, Marie ; Jackson, Andrew P. ; Jayatunga, Rasieka ; Jiang, Yong-Hui ; Kant, Sarina G. ; Kao, Amy ; King, Mary D. ; Kingston, Helen M. ; Klepper, Joerg ; van der Knaap, Marjo S. ; Kornberg, Andrew J. ; Kotzot, Dieter ; Kratzer, Wilfried ; Lacombe, Didier ; Lagae, Lieven ; Landrieu, Pierre Georges ; Lanzi, Giovanni ; Leitch, Andrea ; Lim, Ming J. ; Livingston, John H. ; Lourenco, Charles M. ; Lyall, E. G. Hermione ; Lynch, Sally A. ; Lyons, Michael J. ; Marom, Daphna ; McClure, John P. ; McWilliam, Robert ; Melancon, Serge B. ; Mewasingh, Leena D. ; Moutard, Marie-Laure ; Nischal, Ken K. ; Østergaard, John R. ; Prendiville, Julie ; Rasmussen, Magnhild ; Rogers, R. Curtis ; Roland, Dominique ; Rosser, Elisabeth M. ; Rostasy, Kevin ; Roubertie, Agathe ; Sanchis, Amparo ; Schiffmann, Raphael ; Scholl-Bürgi, Sabine ; Seal, Sunita ; Shalev, Stavit A. ; Corcoles, C. Sierra ; Sinha, Gyan P. ; Soler, Doriette ; Spiegel, Ronen ; Stephenson, John B. P. ; Tacke, Uta ; Tan, Tiong Yang ; Till, Marianne ; Tolmie, John L. ; Tomlin, Pam ; Vagnarelli, Federica ; Valente, Enza Maria ; Van Coster, Rudy N. A. ; Van der Aa, Nathalie ; Vanderver, Adeline ; Vles, Johannes S. H. ; Voit, Thomas ; Wassmer, Evangeline ; Weschke, Bernhard ; Whiteford, Margo L. ; Willemsen, Michel A. A. ; Zankl, Andreas ; Zuberi, Sameer M. ; Orcesi, Simona ; Fazzi, Elisa ; Lebon, Pierre ; Crow, Yanick J.
2007-01-01
Aicardi-Goutières syndrome (AGS) is a genetic encephalopathy whose clinical features mimic those of acquired in utero viral infection. AGS exhibits locus heterogeneity, with mutations identified in genes encoding the 3′→5′ exonuclease TREX1 and the three subunits of the RNASEH2 endonuclease complex. To define the molecular spectrum of AGS, we performed mutation screening in patients, from 127 pedigrees, with a clinical diagnosis of the disease. Biallelic mutations in TREX1, RNASEH2A, RNASEH2B, and RNASEH2C were observed in 31, 3, 47, and 18 families, respectively. In five families, we identified an RNASEH2A or RNASEH2B mutation on one allele only. In one child, the disease occurred because of a de novo heterozygous TREX1 mutation. In 22 families, no mutations were found. Null mutations were common in TREX1, although a specific missense mutation was observed frequently in patients from northern Europe. Almost all mutations in RNASEH2A, RNASEH2B, and RNASEH2C were missense. We identified an RNASEH2C founder mutation in 13 Pakistani families. We also collected clinical data from 123 mutation-positive patients. Two clinical presentations could be delineated: an early-onset neonatal form, highly reminiscent of congenital infection seen particularly with TREX1 mutations, and a later-onset presentation, sometimes occurring after several months of normal development and occasionally associated with remarkably preserved neurological function, most frequently due to RNASEH2B mutations. Mortality was correlated with genotype; 34.3% of patients with TREX1, RNASEH2A, and RNASEH2C mutations versus 8.0% RNASEH2B mutation–positive patients were known to have died (P=.001). Our analysis defines the phenotypic spectrum of AGS and suggests a coherent mutation-screening strategy in this heterogeneous disorder. Additionally, our data indicate that at least one further AGS-causing gene remains to be identified. PMID:17846997
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The Role of Prokineticins in the Pathogenesis of Hypogonadotropic Hypogonadism
Abreu, Ana Paula; Kaiser, Ursula B.; Latronico, Ana Claudia
2010-01-01
The prokineticin system comprises two multifunctional secreted proteins, prokineticin-1 (PROK1) and prokineticin-2 (PROK2), and their cognate G protein-coupled receptors. The prokineticins were originally identified as endogenous regulators of gastrointestinal motility. Currently, these bioactive peptides are involved in a wide spectrum of biological functions, including angiogenesis, neurogenesis, circadian rhythms, nociception, hematopoiesis and immune response. Mice homozygous for null mutations in Prokr2 or Prok2 recapitulate the human phenotype of Kallmann syndrome, exhibiting severe atrophy of the reproductive system and hypoplastic olfactory bulbs. Indeed, the evidence from several naturally inactivating mutations in the PROK2 and PROKR2 genes in patients with Kallmann syndrome and normosmic hypogonadotropic hypogonadism also indicate the essential role of PROK2 in olfactory bulb morphogenesis and GnRH secretion in humans. PMID:20502053
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Natural killer T cell facilitated engraftment of rat skin but not islet xenografts in mice.
Gordon, Ethel J; Kelkar, Vinaya
2009-01-01
We have studied cellular components required for xenograft survival mediated by anti-CD154 monoclonal antibody (mAb) and a transfusion of donor spleen cells and found that the elimination of CD4(+) but not CD8(+) cells significantly improves graft survival. A contribution of other cellular components, such as natural killer (NK) cells and natural killer T (NKT) cells, for costimulation blockade-induced xenograft survival has not been clearly defined. We therefore tested the hypothesis that NK or NKT cells would promote rat islet and skin xenograft acceptance in mice. Lewis rat islets or skin was transplanted into wild type B6 mice or into B6 mice that were Jalpha18(null), CD1(null), or beta2 microglobulin (beta2M)(null) NK 1.1 depleted, or perforin(null). Graft recipients were pretreated with an infusion of donor derived spleen cells and a brief course of anti-CD154 mAb treatments. Additional groups received mAb or cells only. We first observed that the depletion of NK1.1 cells does not significantly interfere with graft survival in C57BL/6 (B6) mice. We used NKT cell deficient B6 mice to test the hypothesis that NKT cells are involved in islet and skin xenograft survival in our model. These mice bear a null mutation in the gene for the Jalpha18 component of the T-cell receptor. The component is uniquely associated with NKT cells. We found no difference in islet xenograft survival between Jalpha18(null) and wild type B6 mice. In contrast, median skin graft survival appeared shorter in Jalpha18(null) recipients. These data imply a role for Jalpha18(+) NKT cells in skin xenograft survival in treated mice. In order to confirm this inference, we tested skin xenograft survival in B6 CD1(null) mice because NKT cells are CD1 restricted. Results of these trials demonstrate that the absence of CD1(+) cells adversely affects rat skin graft survival. An additional assay in beta2M(null) mice demonstrated a requirement for major histocompatibility complex (MHC) class I expression in the graft host, and we demonstrate that CD1 is the requisite MHC component. We further demonstrated that, unlike reports for allograft survival, skin xenograft survival does not require perforin-secreting NK cells. We conclude that MHC class I(+) CD1(+) Jalpha18(+) NKT cells promote the survival of rat skin but not rat islet xenografts. These studies implicate different mechanisms for inducing and maintaining islet vs. skin xenograft survival in mice treated with donor antigen and anti-CD154 mAb, and further indicate a role for NKT cells but not NK cells in skin xenograft survival.
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Prajapati, Saumya; Tao, Jinhui; Ruan, Qichao; De Yoreo, James J.; Moradian-Oldak, Janet
2015-01-01
Reconstruction of enamel-like materials is a central topic of research in dentistry and material sciences. The importance of precise proteolytic mechanisms in amelogenesis to form a hard tissue with more than 95% mineral content has already been reported. A mutation in the Matrix Metalloproteinase-20 (MMP-20) gene results in hypomineralized enamel that is thin, disorganized and breaks from the underlying dentin. We hypothesized that the absence of MMP-20 during amelogenesis results in the occlusion of amelogenin in the enamel hydroxyapatite crystals. We used spectroscopy and electron microscopy techniques to qualitatively and quantitatively analyze occluded proteins within the isolated enamel crystals from MMP-20 null and Wild type (WT) mice. Our results showed that the isolated enamel crystals of MMP-20 null mice had more organic macromolecules occluded inside them than enamel crystals from the WT. The crystal lattice arrangements of MMP-20 null enamel crystals analyzed by High Resolution Transmission Electron Microscopy (HRTEM) were found to be significantly different from those of the WT. Raman studies indicated that the crystallinity of the MMP-20 null enamel crystals was lower than that of the WT. In conclusion, we present a novel functional mechanism of MMP-20, specifically prevention of unwanted organic material entrapped in the forming enamel crystals, which occurs as the result of precise amelogenin cleavage. MMP-20 action guides the growth morphology of the forming hydroxyapatite crystals and enhances their crystallinity. Elucidating such molecular mechanisms can be applied in the design of novel biomaterials for future clinical applications in dental restoration or repair. PMID:26513418
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Prajapati, Saumya; Tao, Jinhui; Ruan, Qichao; De Yoreo, James J; Moradian-Oldak, Janet
2016-01-01
Reconstruction of enamel-like materials is a central topic of research in dentistry and material sciences. The importance of precise proteolytic mechanisms in amelogenesis to form a hard tissue with more than 95% mineral content has already been reported. A mutation in the Matrix Metalloproteinase-20 (MMP-20) gene results in hypomineralized enamel that is thin, disorganized and breaks from the underlying dentin. We hypothesized that the absence of MMP-20 during amelogenesis results in the occlusion of amelogenin in the enamel hydroxyapatite crystals. We used spectroscopy and electron microscopy techniques to qualitatively and quantitatively analyze occluded proteins within the isolated enamel crystals from MMP-20 null and Wild type (WT) mice. Our results showed that the isolated enamel crystals of MMP-20 null mice had more organic macromolecules occluded inside them than enamel crystals from the WT. The crystal lattice arrangements of MMP-20 null enamel crystals analyzed by High Resolution Transmission Electron Microscopy (HRTEM) were found to be significantly different from those of the WT. Raman studies indicated that the crystallinity of the MMP-20 null enamel crystals was lower than that of the WT. In conclusion, we present a novel functional mechanism of MMP-20, specifically prevention of unwanted organic material entrapped in the forming enamel crystals, which occurs as the result of precise amelogenin cleavage. MMP-20 action guides the growth morphology of the forming hydroxyapatite crystals and enhances their crystallinity. Elucidating such molecular mechanisms can be applied in the design of novel biomaterials for future clinical applications in dental restoration or repair. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Zhang, Yong Q; Friedman, David B; Wang, Zhe; Woodruff, Elvin; Pan, Luyuan; O'donnell, Janis; Broadie, Kendal
2005-03-01
Fragile X syndrome is the most common form of inherited mental retardation, associated with both cognitive and behavioral anomalies. The disease is caused by silencing of the fragile X mental retardation 1 (fmr1) gene, which encodes the mRNA-binding, translational regulator FMRP. Previously we established a disease model through mutation of Drosophila fmr1 (dfmr1) and showed that loss of dFMRP causes defects in neuronal structure, function, and behavioral output similar to the human disease state. To uncover molecular targets of dFMRP in the brain, we use here a proteomic approach involving two-dimensional difference gel electrophoresis analyses followed by mass spectrometry identification of proteins with significantly altered expression in dfmr1 null mutants. We then focus on two misregulated enzymes, phenylalanine hydroxylase (Henna) and GTP cyclohydrolase (Punch), both of which mediate in concert the synthetic pathways of two key monoamine neuromodulators, dopamine and serotonin. Brain enzymatic assays show a nearly 2-fold elevation of Punch activity in dfmr1 null mutants. Consistently brain neurochemical assays show that both dopamine and serotonin are significantly increased in dfmr1 null mutants. At a cellular level, dfmr1 null mutant neurons display a highly significant elevation of the dense core vesicles that package these monoamine neuromodulators for secretion. Taken together, these data indicate that dFMRP normally down-regulates the monoamine pathway, which is consequently up-regulated in the mutant condition. Elevated brain levels of dopamine and serotonin provide a plausible mechanistic explanation for aspects of cognitive and behavioral deficits in human patients.
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Buffering of protons released by mineral formation during amelogenesis in mice.
Bronckers, Antonius L J J; Lyaruu, Don M; Jalali, Rozita; DenBesten, Pamela K
2016-10-01
Regulation of pH by ameloblasts during amelogenesis is critical for enamel mineralization. We examined the effects of reduced bicarbonate secretion and the presence or absence of amelogenins on ameloblast modulation and enamel mineralization. To that end, the composition of fluorotic and non-fluorotic enamel of several different mouse mutants, including enamel of cystic fibrosis transmembrane conductance regulator-deficient (Cftr null), anion exchanger-2-deficient (Ae2a,b null), and amelogenin-deficient (Amelx null) mice, was determined by quantitative X-ray microanalysis. Correlation analysis was carried out to compare the effects of changes in the levels of sulfated-matrix (S) and chlorine (Cl; for bicarbonate secretion) on mineralization and modulation. The chloride (Cl - ) levels in forming enamel determined the ability of ameloblasts to modulate, remove matrix, and mineralize enamel. In general, the lower the Cl - content, the stronger the negative effects. In Amelx-null mice, modulation was essentially normal and the calcium content was reduced least. Retention of amelogenins in enamel of kallikrein-4-deficient (Klk4-null) mice resulted in decreased mineralization and reduced the length of the first acid modulation band without changing the total length of all acidic bands. These data suggest that buffering by bicarbonates is critical for modulation, matrix removal and enamel mineralization. Amelogenins also act as a buffer but are not critical for modulation. © 2016 Eur J Oral Sci.
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El-Hoss, Jad; Sullivan, Kate; Cheng, Tegan; Yu, Nicole Y C; Bobyn, Justin D; Peacock, Lauren; Mikulec, Kathy; Baldock, Paul; Alexander, Ian E; Schindeler, Aaron; Little, David G
2012-01-01
Neurofibromatosis type 1 (NF1) is a common genetic condition caused by mutations in the NF1 gene. Patients often suffer from tissue-specific lesions associated with local double-inactivation of NF1. In this study, we generated a novel fracture model to investigate the mechanism underlying congenital pseudarthrosis of the tibia (CPT) associated with NF1. We used a Cre-expressing adenovirus (AdCre) to inactivate Nf1 in vitro in cultured osteoprogenitors and osteoblasts, and in vivo in the fracture callus of Nf1(flox/flox) and Nf1(flox/-) mice. The effects of the presence of Nf1(null) cells were extensively examined. Cultured Nf1(null)-committed osteoprogenitors from neonatal calvaria failed to differentiate and express mature osteoblastic markers, even with recombinant bone morphogenetic protein-2 (rhBMP-2) treatment. Similarly, Nf1(null)-inducible osteoprogenitors obtained from Nf1 MyoDnull mouse muscle were also unresponsive to rhBMP-2. In both closed and open fracture models in Nf1(flox/flox) and Nf1(flox/-) mice, local AdCre injection significantly impaired bone healing, with fracture union being <50% that of wild type controls. No significant difference was seen between Nf1(flox/flox) and Nf1(flox/-) mice. Histological analyses showed invasion of the Nf1(null) fractures by fibrous and highly proliferative tissue. Mean amounts of fibrous tissue were increased upward of 10-fold in Nf1(null) fractures and bromodeoxyuridine (BrdU) staining in closed fractures showed increased numbers of proliferating cells. In Nf1(null) fractures, tartrate-resistant acid phosphatase-positive (TRAP+) cells were frequently observed within the fibrous tissue, not lining a bone surface. In summary, we report that local Nf1 deletion in a fracture callus is sufficient to impair bony union and recapitulate histological features of clinical CPT. Cell culture findings support the concept that Nf1 double inactivation impairs early osteoblastic differentiation. This model provides valuable insight into the pathobiology of the disease, and will be helpful for trialing therapeutic compounds. Copyright © 2012 American Society for Bone and Mineral Research.
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Cancer Susceptibility Gene Mutations in Individuals With Colorectal Cancer
Yurgelun, Matthew B.; Kulke, Matthew H.; Fuchs, Charles S.; Allen, Brian A.; Uno, Hajime; Hornick, Jason L.; Ukaegbu, Chinedu I.; Brais, Lauren K.; McNamara, Philip G.; Mayer, Robert J.; Schrag, Deborah; Meyerhardt, Jeffrey A.; Ng, Kimmie; Kidd, John; Singh, Nanda; Hartman, Anne-Renee; Wenstrup, Richard J.
2017-01-01
Purpose Hereditary factors play an important role in colorectal cancer (CRC) risk, yet the prevalence of germline cancer susceptibility gene mutations in patients with CRC unselected for high-risk features (eg, early age at diagnosis, personal/family history of cancer or polyps, tumor microsatellite instability [MSI], mismatch repair [MMR] deficiency) is unknown. Patients and Methods We recruited 1,058 participants who received CRC care in a clinic-based setting without preselection for age at diagnosis, personal/family history, or MSI/MMR results. All participants underwent germline testing for mutations in 25 genes associated with inherited cancer risk. Each gene was categorized as high penetrance or moderate penetrance on the basis of published estimates of the lifetime cancer risks conferred by pathogenic germline mutations in that gene. Results One hundred five (9.9%; 95% CI, 8.2% to 11.9%) of 1,058 participants carried one or more pathogenic mutations, including 33 (3.1%) with Lynch syndrome (LS). Twenty-eight (96.6%) of 29 available LS CRCs demonstrated abnormal MSI/MMR results. Seventy-four (7.0%) of 1,058 participants carried non-LS gene mutations, including 23 (2.2%) with mutations in high-penetrance genes (five APC, three biallelic MUTYH, 11 BRCA1/2, two PALB2, one CDKN2A, and one TP53), 15 of whom lacked clinical histories suggestive of their underlying mutation. Thirty-eight (3.6%) participants had moderate-penetrance CRC risk gene mutations (19 monoallelic MUTYH, 17 APC*I1307K, two CHEK2). Neither proband age at CRC diagnosis, family history of CRC, nor personal history of other cancers significantly predicted the presence of pathogenic mutations in non-LS genes. Conclusion Germline cancer susceptibility gene mutations are carried by 9.9% of patients with CRC. MSI/MMR testing reliably identifies LS probands, although 7.0% of patients with CRC carry non-LS mutations, including 1.0% with BRCA1/2 mutations. PMID:28135145
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A Mutation of the Prdm9 Mouse Hybrid Sterility Gene Carried by a Transgene.
Mihola, O; Trachtulec, Z
2017-01-01
PRDM9 is a protein with histone-3-methyltransferase activity, which specifies the sites of meiotic recombination in mammals. Deficiency of the Prdm9 gene in the laboratory mouse results in complete arrest of the meiotic prophase of both sexes. Moreover, the combination of certain PRDM9 alleles from different mouse subspecies causes hybrid sterility, e.g., the male-specific meiotic arrest found in the (PWD/Ph × C57BL/6J)F1 animals. The fertility of all these mice can be rescued using a Prdm9-containing transgene. Here we characterized a transgene made from the clone RP24-346I22 that was expected to encompass the entire Prdm9 gene. Both (PWD/Ph × C57BL/6J)F1 intersubspecific hybrid males and Prdm9-deficient laboratory mice of both sexes carrying this transgene remained sterile, suggesting that Prdm9 inactivation occurred in the Tg(RP24-346I22) transgenics. Indeed, comparative qRT-PCR analysis of testicular RNAs from transgene-positive versus negative animals revealed similar expression levels of Prdm9 mRNAs from the exons encoding the C-terminal part of the protein but elevated expression from the regions coding for the N-terminus of PRDM9, indicating that the transgenic carries a new null Prdm9 allele. Two naturally occurring alternative Prdm9 mRNA isoforms were overexpressed in Tg(RP24-346I22), one formed via splicing to a 3'-terminal exon consisting of short interspersed element B2 and one isoform including an alternative internal exon of 28 base pairs. However, the overexpression of these alternative transcripts was apparently insufficient for Prdm9 function or for increasing the fertility of the hybrid males.
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Gu, S M; Orth, U; Zankl, M; Schröder, J; Gal, A
1997-08-22
Eight novel mutations were identified in the gene encoding L1CAM, a neural cell adhesion protein, in patients/families with X-linked hydrocephalus (XHC) providing additional evidence for extreme allelic heterogeneity of the trait. The two nonsense mutations (Gln440Ter and Gln1042Ter) result most likely in functional null-alleles and complete absence of L1CAM at the cell surface. The four missense mutations (Leu482Pro, Ser542Pro, Met741Thr, and Val752Met) as well as delSer526 may considerably alter the structure of L1CAM. Interestingly, a missense mutation in an XHC family predicting the Val768Ile change in the second fibronectin type III domain of L1CAM was found not only in the two affected cousins and their obligate carrier mothers but also in two unaffected male relatives of the patients. Several possible explanations of this finding are discussed; the most likely being that Val768Ile is a rare non-pathogenic variant. If this were indeed the case, our data suggest that the XHC in this family is not due to a mutation of the L1CAM gene, i.e., that, in addition to the extreme allelic heterogeneity of XHC, a non-allelic form of genetic heterogeneity may also exist in this trait.
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Stanewsky, R.; Fry, T. A.; Reim, I.; Saumweber, H.; Hall, J. C.
1996-01-01
The no-on-transient-A (nonA) gene of Drosophila melanogaster influences vision, courtship song, and viability. The nonA-encoded polypeptide is inferred to bind single-stranded nucleic acids. Although sequence-analysis of NONA implies that it belongs to a special interspecific family of this protein type, it does contain two classical RNA recognition motifs (RRM). Their behavioral significance was assayed by generating transgenic strains that were singly or multiply mutated within the relatively N-terminal motif (RRM1) or within RRM2. Neither class of mutation affected NONA binding to polytene chromosomes. The former mutations led to extremely low viability, accompanied by diminished adult longevities that were much worse than for a nonA-null mutant, implying that faulty interpolypeptide interactions might accompany the effects of the amino-acid substitutions within RRM1. All in vitro-mutated types caused optomotor blindness and an absence of transient spikes in the electroretinogram. Courtship analysis discriminated between the effects of the mutations: the RRM2-mutated type generated song pulses and trains that tended to be mildly mutant. These phenotypic abnormalities reinforce the notion that nonA's ubiquitous expression has its most important consequences in the optic lobes, the thoracic ganglia, or both, depending in part on the nonA allele. PMID:8722780
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Wild-type presenilin 1 protects against Alzheimer disease mutation-induced amyloid pathology.
Wang, Runsheng; Wang, Baiping; He, Wanxia; Zheng, Hui
2006-06-02
Mutations in presenilin 1 (PS1) lead to dominant inheritance of early onset familial Alzheimer disease (FAD). These mutations are known to alter the gamma-secretase cleavage of the amyloid precursor protein, resulting in increased ratio of Abeta42/Abeta40 and accelerated amyloid plaque pathology in transgenic mouse models. To investigate the factors that drive the Abeta42/Abeta40 ratio and amyloid pathogenesis and to investigate the possible interactions between wild-type and FAD mutant PS1, which are co-expressed in transgenic animals, we expressed the PS1 M146V knock-in allele either on wild-type PS1 (PS1M146V/+) or PS1 null (PS1M146V/-) background and crossed these alleles with the Tg2576 APP transgenic mice. Introduction of the PS1 M146V mutation on Tg2576 background resulted in earlier onset of plaque pathology. Surprisingly, removing the wild-type PS1 in the presence of the PS1 M146V mutation (PS1M146V/-) greatly exacerbated the amyloid burden; and this was attributed to a reduction of gamma-secretase activity rather than an increase in Abeta42. Our findings establish a protective role of the wild-type PS1 against the FAD mutation-induced amyloid pathology through a partial loss-of-function mechanism.
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Vazna, Alzbeta; Beesley, Clare; Berna, Linda; Stolnaja, Larisa; Myskova, Helena; Bouckova, Michaela; Vlaskova, Hana; Poupetova, Helena; Zeman, Jiri; Magner, Martin; Hlavata, Anna; Winchester, Bryan; Hrebicek, Martin; Dvorakova, Lenka
2009-01-01
Abstract Mucopolysaccharidosis type I (MPS I) is an autosomal recessive lysosomal storage disorder that is caused by a deficiency of the enzyme α-l-iduronidase (IDUA). Of the 21 Czech and Slovak patients who have been diagnosed with MPS I in the last 30 years, 16 have a severe clinical presentation (Hurler syndrome), 2 less severe manifestations (Scheie syndrome), and 3 an intermediate severity (Hurler/Scheie phenotype). Mutation analysis was performed in 20 MPS I patients and 39 mutant alleles were identified. There was a high prevalence of the null mutations p.W402X (12 alleles) and p.Q70X (7 alleles) in this cohort. Four of the 13 different mutations were novel: p.V620F (3 alleles), p.W626X (1 allele), c.1727 + 2T > G (1 allele) and c.1918_1927del (2 alleles). The pathogenicity of the novel mutations was verified by transient expression studies in Chinese hamster ovary cells. Seven haplotypes were observed in the patient alleles using 13 intragenic polymorphisms. One of the two haplotypes associated with the mutation p.Q70X was not found in any of the controls. Haplotype analysis showed, that mutations p.Q70X, p.V620F, and p.D315Y probably have more than one ancestor. Missense mutations localized predominantly in the hydrophobic core of the enzyme are associated with the severe phenotype, whereas missense mutations localized to the surface of the enzyme are usually associated with the attenuated phenotypes. Mutations in the 130 C-terminal amino acids lead to clinical manifestations, which indicates a functional importance of the C-terminus of the IDUA protein. © 2009 Wiley-Liss, Inc. PMID:19396826
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CLINICAL PRESENTATION AND DISEASE COURSE OF USHER SYNDROME BECAUSE OF MUTATIONS IN MYO7A OR USH2A.
Testa, Francesco; Melillo, Paolo; Bonnet, Crystel; Marcelli, Vincenzo; de Benedictis, Antonella; Colucci, Raffaella; Gallo, Beatrice; Kurtenbach, Anne; Rossi, Settimio; Marciano, Elio; Auricchio, Alberto; Petit, Christine; Zrenner, Eberhart; Simonelli, Francesca
2017-08-01
To evaluate differences in the visual phenotype and natural history of Usher syndrome caused by mutations in MYO7A or USH2A, the most commonly affected genes of Usher syndrome Type I (USH1) and Type II (USH2), respectively. Eighty-eight patients with a clinical diagnosis of USH1 (26 patients) or USH2 (62 patients) were retrospectively evaluated. Of these, 48 patients had 2 disease-causing mutations in MYO7A (10 USH1 patients), USH2A (33 USH2 patients), and other USH (5 patients) genes. Clinical investigation included best-corrected visual acuity, Goldmann visual field, fundus photography, electroretinography, and audiologic and vestibular assessments. Longitudinal analysis was performed over a median follow-up time of 3.5 years. Patients carrying mutations in MYO7A had a younger age of onset of hearing and visual impairments than those carrying mutations in USH2A, leading to an earlier diagnosis of the disease in the former patients. Longitudinal analysis showed that visual acuity and visual field decreased more rapidly in subjects carrying MYO7A mutations than in those carrying USH2A mutations (mean annual exponential rates of decline of 3.92 vs. 3.44% and of 8.52 vs. 4.97%, respectively), and the former patients reached legal blindness on average 15 years earlier than the latter. The current study confirmed a more severe progression of the retinal disease in USH1 patients rather than in USH2 patients. Furthermore, most visual symptoms (i.e., night blindness, visual acuity worsening) occurred at an earlier age in USH1 patients carrying mutations in MYO7A.
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The Spectrum of WRN Mutations in Werner Syndrome Patients
Huang, Shurong; Lee, Lin; Hanson, Nancy B.; Lenaerts, Catherine; Hoehn, Holger; Poot, Martin; Rubin, Craig D.; Chen, Da-Fu; Yang, Chih-Chao; Juch, Heike; Dorn, Thomas; Spiegel, Roland; Oral, Elif Arioglu; Abid, Mohammed; Battisti, Carla; Lucci-Cordisco, Emanuela; Neri, Giovanni; Steed, Erin H.; Kidd, Alexa; Isley, William; Showalter, David; Vittone, Janet L.; Konstantinow, Alexander; Ring, Johannes; Meyer, Peter; Wenger, Sharon L.; von Herbay, Axel; Wollina, Uwe; Schuelke, Markus; Huizenga, Carin R.; Leistritz, Dru F.; Martin, George M.; Mian, I. Saira; Oshima, Junko
2007-01-01
The International Registry of Werner syndrome (www.wernersyndrome.org) has been providing molecular diagnosis of the Werner syndrome (WS) for the past decade. The present communication summarizes, from among 99 WS subjects, the spectrum of 50 distinct mutations discovered by our group and by others since the WRN gene (also called RECQL2 or REQ3) was first cloned in 1996; 25 of these have not previously been published. All WRN mutations reported thus far have resulted in the elimination of the nuclear localization signal at the C-terminus of the protein, precluding functional interactions in the nucleus; thus, all could be classified as null mutations. We now report two new mutations in the N-terminus that result in instability of the WRN protein. Clinical data confirm that the most penetrant phenotype is bilateral ocular cataracts. Other cardinal signs were seen in more than 95% of the cases. The median age of death, previously reported to be in the range of 46–48 years, is 54 years. Lymphoblastoid cell lines (LCLs) have been cryopreserved from the majority of our index cases, including material from nuclear pedigrees. These, as well as inducible and complemented hTERT (catalytic subunit of human telomerase) immortalized skin fibroblast cell lines are available to qualified investigators. Published 2006 Wiley-Liss, Inc.† PMID:16673358
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Mutations in eukaryotic release factors 1 and 3 act as general nonsense suppressors in Drosophila.
Chao, Anna T; Dierick, Herman A; Addy, Tracie M; Bejsovec, Amy
2003-01-01
In a screen for suppressors of the Drosophila wingless(PE4) nonsense allele, we isolated mutations in the two components that form eukaryotic release factor. eRF1 and eRF3 comprise the translation termination complex that recognizes stop codons and catalyzes the release of nascent polypeptide chains from ribosomes. Mutations disrupting the Drosophila eRF1 and eRF3 show a strong maternal-effect nonsense suppression due to readthrough of stop codons and are zygotically lethal during larval stages. We tested nonsense mutations in wg and in other embryonically acting genes and found that different stop codons can be suppressed but only a subset of nonsense alleles are subject to suppression. We suspect that the context of the stop codon is significant: nonsense alleles sensitive to suppression by eRF1 and eRF3 encode stop codons that are immediately followed by a cytidine. Such suppressible alleles appear to be intrinsically weak, with a low level of readthrough that is enhanced when translation termination is disrupted. Thus the eRF1 and eRF3 mutations provide a tool for identifying nonsense alleles that are leaky. Our findings have important implications for assigning null mutant phenotypes and for selecting appropriate alleles to use in suppressor screens. PMID:14573473
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Mutations in STAT3 and IL12RB1 impair the development of human IL-17–producing T cells
de Beaucoudrey, Ludovic; Puel, Anne; Filipe-Santos, Orchidée; Cobat, Aurélie; Ghandil, Pegah; Chrabieh, Maya; Feinberg, Jacqueline; von Bernuth, Horst; Samarina, Arina; Jannière, Lucile; Fieschi, Claire; Stéphan, Jean-Louis; Boileau, Catherine; Lyonnet, Stanislas; Jondeau, Guillaume; Cormier-Daire, Valérie; Le Merrer, Martine; Hoarau, Cyrille; Lebranchu, Yvon; Lortholary, Olivier; Chandesris, Marie-Olivia; Tron, François; Gambineri, Eleonora; Bianchi, Lucia; Rodriguez-Gallego, Carlos; Zitnik, Simona E.; Vasconcelos, Julia; Guedes, Margarida; Vitor, Artur Bonito; Marodi, Laszlo; Chapel, Helen; Reid, Brenda; Roifman, Chaim; Nadal, David; Reichenbach, Janine; Caragol, Isabel; Garty, Ben-Zion; Dogu, Figen; Camcioglu, Yildiz; Gülle, Sanyie; Sanal, Ozden; Fischer, Alain; Abel, Laurent; Stockinger, Birgitta; Picard, Capucine; Casanova, Jean-Laurent
2008-01-01
The cytokines controlling the development of human interleukin (IL) 17–producing T helper cells in vitro have been difficult to identify. We addressed the question of the development of human IL-17–producing T helper cells in vivo by quantifying the production and secretion of IL-17 by fresh T cells ex vivo, and by T cell blasts expanded in vitro from patients with particular genetic traits affecting transforming growth factor (TGF) β, IL-1, IL-6, or IL-23 responses. Activating mutations in TGFB1, TGFBR1, and TGFBR2 (Camurati-Engelmann disease and Marfan-like syndromes) and loss-of-function mutations in IRAK4 and MYD88 (Mendelian predisposition to pyogenic bacterial infections) had no detectable impact. In contrast, dominant-negative mutations in STAT3 (autosomal-dominant hyperimmunoglobulin E syndrome) and, to a lesser extent, null mutations in IL12B and IL12RB1 (Mendelian susceptibility to mycobacterial diseases) impaired the development of IL-17–producing T cells. These data suggest that IL-12Rβ1– and STAT-3–dependent signals play a key role in the differentiation and/or expansion of human IL-17–producing T cell populations in vivo. PMID:18591412
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Mutation analysis of 28 gaucher disease patients: The Australasian experience
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lewis, B.D.; Nelson, P.V.; Robertson, E.F.
1994-01-15
Gaucher disease is the most common lysomal storage disease. It is an autosomal recessive disorder that results from a deficiency of {beta}-glucocerrebrosidase. Three clinical phenotypes have been described: non-neuronopathic, acute neuronopathic, and subacuteneuronopathic. Genomic DNA from 28 Australasian patients of diverse ethnic origin with Gaucher disease was screened for 3 common mutations (1226G, 1448C and 84GG) using the amplification refractory mutation system (ARMS), and one uncommon mutation (1504T) by restriction enzyme digestion. Thirty-eight of the 56 independent alleles in these patients were characterized, with 1448C present in 42% and 1226G in 28% of the alleles. The 1226G mutation was associatedmore » only with the nonneuronopathic phenotype and 7 of the 15 patients who carried the 1448C mutation developed neuronopathic disease. Three infants who died in the neonatal period following a rapidly progressive neurodegenerative course carried no identifiable mutations. The 84GG mutation was carried by 2 Jewish patients and 1504T was present in one patient. It is now possible to rapidly identify the common Gaucher mutations using ARMS and restriction enzyme digestion, and our findings confirm the heterogeneity of mutations in Gaucher disease. It is also possible to predict in part the phenotypic outcome when screening patients for these mutations. The authors consider mutation analysis to be of most use in prenatal diagnosis and for carrier detection within affected families. 27 refs., 2 figs., 2 tabs.« less
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Natural disease history of mouse models for limb girdle muscular dystrophy types 2D and 2F
Putker, K.; Tanganyika-de Winter, C. L.; Boertje-van der Meulen, J. W.; van Vliet, L.; Overzier, M.; Plomp, J. J.; Aartsma-Rus, A.; van Putten, M.
2017-01-01
Limb-girdle muscular dystrophy types 2D and 2F (LGMD 2D and 2F) are autosomal recessive disorders caused by mutations in the alpha- and delta sarcoglycan genes, respectively, leading to severe muscle weakness and degeneration. The cause of the disease has been well characterized and a number of animal models are available for pre-clinical studies to test potential therapeutic interventions. To facilitate transition from drug discovery to clinical trials, standardized procedures and natural disease history data were collected for these mouse models. Implementing the TREAD-NMD standardized operating procedures, we here subjected LGMD2D (SGCA-null), LGMD2F (SGCD-null) and wild type (C57BL/6J) mice to five functional tests from the age of 4 to 32 weeks. To assess whether the functional test regime interfered with disease pathology, sedentary groups were taken along. Muscle physiology testing of tibialis anterior muscle was performed at the age of 34 weeks. Muscle histopathology and gene expression was analysed in skeletal muscles and heart. Muscle histopathology and gene expression was analysed in skeletal muscles and heart. Mice successfully accomplished the functional tests, which did not interfere with disease pathology. Muscle function of SGCA- and SGCD-null mice was impaired and declined over time. Interestingly, female SGCD-null mice outperformed males in the two and four limb hanging tests, which proved the most suitable non-invasive tests to assess muscle function. Muscle physiology testing of tibialis anterior muscle revealed lower specific force and higher susceptibility to eccentric-induced damage in LGMD mice. Analyzing muscle histopathology and gene expression, we identified the diaphragm as the most affected muscle in LGMD strains. Cardiac fibrosis was found in SGCD-null mice, being more severe in males than in females. Our study offers a comprehensive natural history dataset which will be useful to design standardized tests and future pre-clinical studies in LGMD2D and 2F mice. PMID:28797108
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A missense mutation in Fgfr1 causes ear and skull defects in hush puppy mice.
Calvert, Jennifer A; Dedos, Skarlatos G; Hawker, Kelvin; Fleming, Michelle; Lewis, Morag A; Steel, Karen P
2011-06-01
The hush puppy mouse mutant has been shown previously to have skull and outer, middle, and inner ear defects, and an increase in hearing threshold. The fibroblast growth factor receptor 1 (Fgfr1) gene is located in the region of chromosome 8 containing the mutation. Sequencing of the gene in hush puppy heterozygotes revealed a missense mutation in the kinase domain of the protein (W691R). Homozygotes were found to die during development, at approximately embryonic day 8.5, and displayed a phenotype similar to null mutants. Reverse transcription PCR indicated a decrease in Fgfr1 transcript in heterozygotes and homozygotes. Generation of a construct containing the mutation allowed the function of the mutated receptor to be studied. Immunocytochemistry showed that the mutant receptor protein was present at the cell membrane, suggesting normal expression and trafficking. Measurements of changes in intracellular calcium concentration showed that the mutated receptor could not activate the IP(3) pathway, in contrast to the wild-type receptor, nor could it initiate activation of the Ras/MAP kinase pathway. Thus, the hush puppy mutation in fibroblast growth factor receptor 1 appears to cause a loss of receptor function. The mutant protein appears to have a dominant negative effect, which could be due to it dimerising with the wild-type protein and inhibiting its activity, thus further reducing the levels of functional protein. A dominant modifier, Mhspy, which reduces the effect of the hush puppy mutation on pinna and stapes development, has been mapped to the distal end of chromosome 7 and may show imprinting.
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Do BRCA1/2 mutation carriers have an earlier onset of natural menopause?
van Tilborg, Theodora C; Broekmans, Frank J; Pijpe, Anouk; Schrijver, Lieske H; Mooij, Thea M; Oosterwijk, Jan C; Verhoef, Senno; Gómez Garcia, Encarna B; van Zelst-Stams, Wendy A; Adank, Muriel A; van Asperen, Christi J; van Doorn, Helena C; van Os, Theo A; Bos, Anna M; Rookus, Matti A; Ausems, Margreet G
2016-08-01
It has been hypothesized that BRCA1/2 mutation carriers have an earlier age at natural menopause (ANM), although to date findings are inconclusive. This study assessed the influence of BRCA mutation status on ANM, and aimed to explore the reasons of inconsistency in the literature. Cross-sectional assessment from an ongoing nationwide cohort study among members of BRCA1/2 mutated families. Information was obtained by a standardized questionnaire. Kaplan-Meier curves were constructed, and Cox regression was used to assess the association between BRCA1/2 mutation status and ANM. Adjustments were made for birth cohort, family, smoking, use of hormonal contraceptives, and parity. A total of 1,208 BRCA1/2 mutation carriers and 2,211 proven noncarriers were included. Overall, no association was found between BRCA1/2 mutation status and ANM (adjusted hazard ratio [HR] = 1.06 [95% CI, 0.87-1.30]). We examined if the null finding was due to informative censoring by uptake of risk-reducing salpingo-oophorectomy. Indeed, within the oldest birth cohort, in which the percentage of surgical menopause events was lowest and comparable between carriers and noncarriers, the HR for earlier natural menopause in carriers was 1.45 (95% CI, 1.09-1.94). The second oldest birth cohort, however, demonstrated a decreased HR (0.67 [95% CI, 0.46-0.98]), and thus no trend over birth cohorts was found. Various types of selection bias hamper the comparison of ANM between BRCA1/2 mutation carriers and noncarriers, genetically tested in the clinic.
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Shaikh, Samiha S; Chen, Ya-Chun; Halsall, Sally-Anne; Nahorski, Michael S; Omoto, Kiyoyuki; Young, Gareth T; Phelan, Anne; Woods, Christopher Geoffrey
2017-01-01
Hereditary sensory and autonomic neuropathy type IV (HSAN IV) is an autosomal recessive disorder characterized by a complete lack of pain perception and anhidrosis. Here, we studied a cohort of seven patients with HSAN IV and describe a comprehensive functional analysis of seven novel NTRK1 missense mutations, c.1550G >A, c.1565G >A, c.1970T >C, c.2096T >C, c.2254T >A, c.2288G >C, and c.2311C >T, corresponding to p.G517E, p.G522E, p.L657P, p.I699T, p.C752S, p.C763S, and p.R771C, all of which were predicted pathogenic by in silico analysis. The results allowed us to assess the pathogenicity of each mutation and to gain novel insights into tropomyosin receptor kinase A (TRKA) downstream signaling. Each mutation was systematically analyzed for TRKA glycosylation states, intracellular and cell membrane expression patterns, nerve growth factor stimulated TRKA autophosphorylation, TRKA-Y496 phosphorylation, PLCγ activity, and neurite outgrowth. We showed a diverse range of functional effects: one mutation appeared fully functional, another had partial activity in all assays, one mutation affected only the PLCγ pathway and four mutations were proved null in all assays. Thus, we conclude that complete abolition of TRKA kinase activity is not the only pathogenic mechanism underlying HSAN IV. By corollary, the assessment of the clinical pathogenicity of HSAN IV mutations is more complex than initially predicted and requires a multifaceted approach. © 2016 WILEY PERIODICALS, INC.
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Huang, Zhuo; Ye, Jun; Han, Lianshu; Qiu, Wenjuan; Zhang, Huiwen; Yu, Yongguo; Liang, Lili; Gong, Zhuwen; Gu, Xuefan
2016-04-01
Congenital lipoid adrenal hyperplasia (CLAH) is a rare autosomal recessive disorder caused by defective synthesis of all steroids. This disorder is characterized by 46,XY sex reversal, skin hyperpigmentation, early-onset adrenal crisis and enlarged adrenal with fatty accumulation. CLAH is caused by mutations in the STAR gene. The clinical features and STAR gene mutation spectrum of a large cohort of Chinese patients with CLAH were not reported previously. We performed clinical retrospective review and genetic analysis of the STAR gene in ten unrelated Chinese phenotypic female patients who were clinically diagnosed with CLAH and followed up in our hospital from 2006 to 2015. All ten patients, including two 46,XY females and eight 46,XX females, presented skin hyperpigmentation and early salt-wasting episode, and showed normal growth and development after steroid replacement treatment. Totally 20 mutant alleles containing 11 different STAR gene mutations were identified in these ten patients, including five novel variants (two missense and three null variants), all predicted to be pathogenic in bioinformatics analysis, and six mutations described in previous literature. Among these 11 mutations, a reported mutation c.772C>T and a novel variant c.707_708delinsCTT were most frequent, accounting for 35% and 15% of the total mutant alleles, respectively. This is the first report of a large Chinese cohort with CLAH, presenting the mutation spectrum of the STAR gene and two possible founder mutations in the Chinese population, which may contribute to better genetic counseling and prenatal diagnosis. Copyright © 2016 Elsevier Inc. All rights reserved.
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CDKL5 regulates flagellar length and localizes to the base of the flagella in Chlamydomonas
Tam, Lai-Wa; Ranum, Paul T.; Lefebvre, Paul A.
2013-01-01
The length of Chlamydomonas flagella is tightly regulated. Mutations in four genes—LF1, LF2, LF3, and LF4—cause cells to assemble flagella up to three times wild-type length. LF2 and LF4 encode protein kinases. Here we describe a new gene, LF5, in which null mutations cause cells to assemble flagella of excess length. The LF5 gene encodes a protein kinase very similar in sequence to the protein kinase CDKL5. In humans, mutations in this kinase cause a severe form of juvenile epilepsy. The LF5 protein localizes to a unique location: the proximal 1 μm of the flagella. The proximal localization of the LF5 protein is lost when genes that make up the proteins in the cytoplasmic length regulatory complex (LRC)—LF1, LF2, and LF3—are mutated. In these mutants LF5p becomes localized either at the distal tip of the flagella or along the flagellar length, indicating that length regulation involves, at least in part, control of LF5p localization by the LRC. PMID:23283985
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Ersoy Tunalı, Nagehan; Marobbio, Carlo M.T.; Tiryakioğlu, N. Ozan; Punzi, Giuseppe; Saygılı, Seha K.; Önal, Hasan; Palmieri, Ferdinando
2014-01-01
The hyperornithinemia–hyperammonemia–homocitrullinuria syndrome is a rare autosomal recessive disorder caused by the functional deficiency of the mitochondrial ornithine transporter 1 (ORC1). ORC1 is encoded by the SLC25A15 gene and catalyzes the transport of cytosolic ornithine into mitochondria in exchange for citrulline. Although the age of onset and the severity of the symptoms vary widely, the disease usually manifests in early infancy. The typical clinical features include protein intolerance, lethargy, episodic confusion, cerebellar ataxia, seizures and mental retardation. In this study, we identified a novel p.Ala15Val (c.44C > T) mutation by genomic DNA sequencing in a Turkish child presenting severe tantrum, confusion, gait disturbances and loss of speech abilities in addition to hyperornithinemia, hyperammonemia and homocitrullinuria. One hundred Turkish control chromosomes did not possess this variant. The functional effect of the novel mutation was assessed by both complementation of the yeast ORT1 null mutant and transport assays. Our study demonstrates that the A15V mutation dramatically interferes with the transport properties of ORC1 since it was shown to inhibit ornithine transport nearly completely. PMID:24721342
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Trivigno, Catherine; Haerry, Theodor E
2011-02-25
Mutations in the human mitochondrial elongation factor G1 (EF-G1) are recessive lethal and cause death shortly after birth. We have isolated mutations in iconoclast (ico), which encodes the highly conserved Drosophila orthologue of EF-G1. We find that EF-G1 is essential during fly development, but its function is not required in every tissue. In contrast to null mutations, missense mutations exhibit stronger, possibly neomorphic phenotypes that lead to premature death during embryogenesis. Our experiments show that EF-G1 contains a secondary C-terminal nuclear localization signal. Expression of missense mutant forms of EF-G1 can accumulate in the nucleus and cause growth and patterning defects and animal lethality. We find that transgenes that encode mutant human EF-G1 proteins can rescue ico mutants, indicating that the underlying problem of the human disease is not just the loss of enzymatic activity. Our results are consistent with a model where EF-G1 acts as a retrograde signal from mitochondria to the nucleus to slow down cell proliferation if mitochondrial energy output is low.
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Trivigno, Catherine; Haerry, Theodor E.
2011-01-01
Mutations in the human mitochondrial elongation factor G1 (EF-G1) are recessive lethal and cause death shortly after birth. We have isolated mutations in iconoclast (ico), which encodes the highly conserved Drosophila orthologue of EF-G1. We find that EF-G1 is essential during fly development, but its function is not required in every tissue. In contrast to null mutations, missense mutations exhibit stronger, possibly neomorphic phenotypes that lead to premature death during embryogenesis. Our experiments show that EF-G1 contains a secondary C-terminal nuclear localization signal. Expression of missense mutant forms of EF-G1 can accumulate in the nucleus and cause growth and patterning defects and animal lethality. We find that transgenes that encode mutant human EF-G1 proteins can rescue ico mutants, indicating that the underlying problem of the human disease is not just the loss of enzymatic activity. Our results are consistent with a model where EF-G1 acts as a retrograde signal from mitochondria to the nucleus to slow down cell proliferation if mitochondrial energy output is low. PMID:21364917
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Genschel, Jochen; Kadyrova, Lyudmila Y.; Iyer, Ravi R.; Dahal, Basanta K.; Kadyrov, Farid A.; Modrich, Paul
2017-01-01
Eukaryotic MutLα (mammalian MLH1–PMS2 heterodimer; MLH1–PMS1 in yeast) functions in early steps of mismatch repair as a latent endonuclease that requires a mismatch, MutSα/β, and DNA-loaded proliferating cell nuclear antigen (PCNA) for activation. We show here that human PCNA and MutLα interact specifically but weakly in solution to form a complex of approximately 1:1 stoichiometry that depends on PCNA interaction with the C-terminal endonuclease domain of the MutLα PMS2 subunit. Amino acid substitution mutations within a PMS2 C-terminal 721QRLIAP motif attenuate or abolish human MutLα interaction with PCNA, as well as PCNA-dependent activation of MutLα endonuclease, PCNA- and DNA-dependent activation of MutLα ATPase, and MutLα function in in vitro mismatch repair. Amino acid substitution mutations within the corresponding yeast PMS1 motif (723QKLIIP) reduce or abolish mismatch repair in vivo. Coupling of a weak allele within this motif (723AKLIIP) with an exo1Δ null mutation, which individually confer only weak mutator phenotypes, inactivates mismatch repair in the yeast cell. PMID:28439008
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Genschel, Jochen; Kadyrova, Lyudmila Y; Iyer, Ravi R; Dahal, Basanta K; Kadyrov, Farid A; Modrich, Paul
2017-05-09
Eukaryotic MutLα (mammalian MLH1-PMS2 heterodimer; MLH1-PMS1 in yeast) functions in early steps of mismatch repair as a latent endonuclease that requires a mismatch, MutSα/β, and DNA-loaded proliferating cell nuclear antigen (PCNA) for activation. We show here that human PCNA and MutLα interact specifically but weakly in solution to form a complex of approximately 1:1 stoichiometry that depends on PCNA interaction with the C-terminal endonuclease domain of the MutLα PMS2 subunit. Amino acid substitution mutations within a PMS2 C-terminal 721 QRLIAP motif attenuate or abolish human MutLα interaction with PCNA, as well as PCNA-dependent activation of MutLα endonuclease, PCNA- and DNA-dependent activation of MutLα ATPase, and MutLα function in in vitro mismatch repair. Amino acid substitution mutations within the corresponding yeast PMS1 motif ( 723 QKLIIP) reduce or abolish mismatch repair in vivo. Coupling of a weak allele within this motif ( 723 AKLIIP) with an exo1 Δ null mutation, which individually confer only weak mutator phenotypes, inactivates mismatch repair in the yeast cell.
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Characterization of highly efficient heavy-ion mutagenesis in Arabidopsis thaliana.
Kazama, Yusuke; Hirano, Tomonari; Saito, Hiroyuki; Liu, Yang; Ohbu, Sumie; Hayashi, Yoriko; Abe, Tomoko
2011-11-15
Heavy-ion mutagenesis is recognised as a powerful technology to generate new mutants, especially in higher plants. Heavy-ion beams show high linear energy transfer (LET) and thus more effectively induce DNA double-strand breaks than other mutagenic techniques. Previously, we determined the most effective heavy-ion LET (LETmax: 30.0 keV μm(-1)) for Arabidopsis mutagenesis by analysing the effect of LET on mutation induction. However, the molecular structure of mutated DNA induced by heavy ions with LETmax remains unclear. Knowledge of the structure of mutated DNA will contribute to the effective exploitation of heavy-ion beam mutagenesis. Dry Arabidopsis thaliana seeds were irradiated with carbon (C) ions with LETmax at a dose of 400 Gy and with LET of 22.5 keV μm(-1) at doses of 250 Gy or 450 Gy. The effects on mutation frequency and alteration of DNA structure were compared. To characterise the structure of mutated DNA, we screened the well-characterised mutants elongated hypocotyls (hy) and glabrous (gl) and identified mutated DNA among the resulting mutants by high-resolution melting curve, PCR and sequencing analyses. The mutation frequency induced by C ions with LETmax was two-fold higher than that with 22.5 keV μm(-1) and similar to the mutation frequency previously induced by ethyl methane sulfonate. We identified the structure of 22 mutated DNAs. Over 80% of the mutations caused by C ions with both LETs were base substitutions or deletions/insertions of less than 100 bp. The other mutations involved large rearrangements. The C ions with LETmax showed high mutation efficiency and predominantly induced base substitutions or small deletions/insertions, most of which were null mutations. These small alterations can be determined by single-nucleotide polymorphism (SNP) detection systems. Therefore, C ions with LETmax might be useful as a highly efficient reverse genetic system in conjunction with SNP detection systems, and will be beneficial for forward genetics and plant breeding.
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Mutation spectrum of the rhodopsin gene among patients with autosomal dominant retinitis pigmentosa
DOE Office of Scientific and Technical Information (OSTI.GOV)
Dryja, T.P.; Han, L.B.; Cowley, G.S.
1991-10-15
The authors searched for point mutations in every exon of the rhodopsin gene in 150 patients from separate families with autosomal dominant retinitis pigmentosa. Including the 4 mutations the authors reported previously, they found a total of 17 different mutations that correlate with the disease. Each of these mutations is a single-base substitution corresponding to a single amino acid substitution. Based on current models for the structure of rhodopsin, 3 of the 17 mutant amino acids are normally located on the cytoplasmic side of the protein, 6 in transmembrane domains, and 8 on the intradiscal side. Forty-three of the 150more » patients (29%) carry 1 of these mutations, and no patient has more than 1 mutation. In every family with a mutation so far analyzed, the mutation cosegregates with the disease. They found one instance of a mutation in an affected patient that was absent in both unaffected parents (i.e., a new germ-line mutation), indicating that some isolate cases of retinitis pigmentosa carry a mutation of the rhodopsin gene.« less
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de Munnik, Sonja A; Bicknell, Louise S; Aftimos, Salim; Al-Aama, Jumana Y; van Bever, Yolande; Bober, Michael B; Clayton-Smith, Jill; Edrees, Alaa Y; Feingold, Murray; Fryer, Alan; van Hagen, Johanna M; Hennekam, Raoul C; Jansweijer, Maaike C E; Johnson, Diana; Kant, Sarina G; Opitz, John M; Ramadevi, A Radha; Reardon, Willie; Ross, Alison; Sarda, Pierre; Schrander-Stumpel, Constance T R M; Schoots, Jeroen; Temple, I Karen; Terhal, Paulien A; Toutain, Annick; Wise, Carol A; Wright, Michael; Skidmore, David L; Samuels, Mark E; Hoefsloot, Lies H; Knoers, Nine V A M; Brunner, Han G; Jackson, Andrew P; Bongers, Ernie M H F
2012-01-01
Meier–Gorlin syndrome (MGS) is an autosomal recessive disorder characterized by microtia, patellar aplasia/hypoplasia, and short stature. Recently, mutations in five genes from the pre-replication complex (ORC1, ORC4, ORC6, CDT1, and CDC6), crucial in cell-cycle progression and growth, were identified in individuals with MGS. Here, we report on genotype–phenotype studies in 45 individuals with MGS (27 females, 18 males; age 3 months–47 years). Thirty-five individuals had biallelic mutations in one of the five causative pre-replication genes. No homozygous or compound heterozygous null mutations were detected. In 10 individuals, no definitive molecular diagnosis was made. The triad of microtia, absent/hypoplastic patellae, and short stature was observed in 82% of individuals with MGS. Additional frequent clinical features were mammary hypoplasia (100%) and abnormal genitalia (42% predominantly cryptorchidism and hypoplastic labia minora/majora). One individual with ORC1 mutations only had short stature, emphasizing the highly variable clinical spectrum of MGS. Individuals with ORC1 mutations had significantly shorter stature and smaller head circumferences than individuals from other gene categories. Furthermore, compared with homozygous missense mutations, compound heterozygous mutations appeared to have a more severe effect on phenotype, causing more severe growth retardation in ORC4 and more frequently pulmonary emphysema in CDT1. A lethal phenotype was seen in four individuals with compound heterozygous ORC1 and CDT1 mutations. No other clear genotype–phenotype association was observed. Growth hormone and estrogen treatment may be of some benefit, respectively, to growth retardation and breast hypoplasia, though further studies in this patient group are needed. PMID:22333897
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Familial Alzheimer disease-linked mutations specifically disrupt Ca2+ leak function of presenilin 1.
Nelson, Omar; Tu, Huiping; Lei, Tianhua; Bentahir, Mostafa; de Strooper, Bart; Bezprozvanny, Ilya
2007-05-01
Mutations in presenilins are responsible for approximately 40% of all early-onset familial Alzheimer disease (FAD) cases in which a genetic cause has been identified. In addition, a number of mutations in presenilin-1 (PS1) have been suggested to be associated with the occurrence of frontal temporal dementia (FTD). Presenilins are highly conserved transmembrane proteins that support cleavage of the amyloid precursor protein by gamma-secretase. Recently, we discovered that presenilins also function as passive ER Ca(2+) leak channels. Here we used planar lipid bilayer reconstitution assays and Ca(2+) imaging experiments with presenilin-null mouse embryonic fibroblasts to analyze ER Ca(2+) leak function of 6 FAD-linked PS1 mutants and 3 known FTD-associated PS1 mutants. We discovered that L166P, A246E, E273A, G384A, and P436Q FAD mutations in PS1 abolished ER Ca(2+) leak function of PS1. In contrast, A79V FAD mutation or FTD-associated mutations (L113P, G183V, and Rins352) did not appear to affect ER Ca(2+) leak function of PS1 in our experiments. We validated our findings in Ca(2+) imaging experiments with primary fibroblasts obtained from an FAD patient possessing mutant PS1-A246E. Our results indicate that many FAD mutations in presenilins are loss-of-function mutations affecting ER Ca(2+) leak activity. In contrast, none of the FTD-associated mutations affected ER Ca(2+) leak function of PS1, indicating that the observed effects are disease specific. Our observations are consistent with the potential role of disturbed Ca(2+) homeostasis in Alzheimer disease pathogenesis.
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Valli, M; Barnes, A M; Gallanti, A; Cabral, W A; Viglio, S; Weis, M A; Makareeva, E; Eyre, D; Leikin, S; Antoniazzi, F; Marini, J C; Mottes, M
2012-11-01
Deficiency of any component of the ER-resident collagen prolyl 3-hydroxylation complex causes recessive osteogenesis imperfecta (OI). The complex modifies the α1(I)Pro986 residue and contains cartilage-associated protein (CRTAP), prolyl 3-hydroxylase 1 (P3H1) and cyclophilin B (CyPB). Fibroblasts normally secrete about 10% of CRTAP. Most CRTAP mutations cause a null allele and lethal type VII OI. We identified a 7-year-old Egyptian boy with non-lethal type VII OI and investigated the effects of his null CRTAP mutation on collagen biochemistry, the prolyl 3-hydroxylation complex, and collagen in extracellular matrix. The proband is homozygous for an insertion/deletion in CRTAP (c.118_133del16insTACCC). His dermal fibroblasts synthesize fully overmodified type I collagen, and 3-hydroxylate only 5% of α1(I)Pro986. CRTAP transcripts are 10% of control. CRTAP protein is absent from proband cells, with residual P3H1 and normal CyPB levels. Dermal collagen fibril diameters are significantly increased. By immunofluorescence of long-term cultures, we identified a severe deficiency (10-15% of control) of collagen deposited in extracellular matrix, with disorganization of the minimal fibrillar network. Quantitative pulse-chase experiments corroborate deficiency of matrix deposition, rather than increased matrix turnover. We conclude that defects of extracellular matrix, as well as intracellular defects in collagen modification, contribute to the pathology of type VII OI. © 2011 John Wiley & Sons A/S.
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Gα modulates salt-induced cellular senescence and cell division in rice and maize
Urano, Daisuke; Colaneri, Alejandro; Jones, Alan M.
2014-09-16
The plant G-protein network, comprising Gα, Gβ, and Gγ core subunits, regulates development, senses sugar, and mediates biotic and abiotic stress responses. Here in this paper, we report G-protein signalling in the salt stress response using two crop models, rice and maize. Loss-of-function mutations in the corresponding genes encoding the Gα subunit attenuate growth inhibition and cellular senescence caused by sodium chloride (NaCl). Gα null mutations conferred reduced leaf senescence, chlorophyll degradation, and cytoplasm electrolyte leakage under NaCl stress. Sodium accumulated in both wild-type and Gα-mutant shoots to the same levels, suggesting that Gα signalling controls cell death in leavesmore » rather than sodium exclusion in roots. Growth inhibition is probably initiated by osmotic change around root cells, because KCl and MgSO 4 also suppressed seedling growth equally as well as NaCl. NaCl lowered rates of cell division and elongation in the wild-type leaf sheath to the level of the Gα-null mutants; however there was no NaCl-induced decrease in cell division in the Gα mutant, implying that the osmotic phase of salt stress suppresses cell proliferation through the inhibition of Gα-coupled signalling. These results reveal two distinct functions of Gα in NaCl stress in these grasses: attenuation of leaf senescence caused by sodium toxicity in leaves, and cell cycle regulation by osmotic/ionic stress.« less
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Trigger Factor can antagonize both SecB and DnaK/DnaJ chaperone functions in Escherichia coli
Ullers, Ronald S.; Ang, Debbie; Schwager, Françoise; Georgopoulos, Costa; Genevaux, Pierre
2007-01-01
Polypeptides emerging from the ribosome are assisted by a pool of molecular chaperones and targeting factors, which enable them to efficiently partition as cytoplasmic, integral membrane, or exported proteins. In Escherichia coli, the chaperones SecB, Trigger Factor (TF), and DnaK are key players in this process. Here, we report that, as with dnaK or dnaJ mutants, a secB null strain exhibits a strong cold-sensitive (Cs) phenotype. Through suppressor analyses, we found that inactivating mutations in the tig gene encoding TF fully relieve both the Cs phenotype and protein aggregation observed in the absence of SecB. This antagonistic effect of TF depends on its ribosome-binding and chaperone activities but unrelated to its peptidyl-prolyl cis/trans isomerase (PPIase) activity. Furthermore, in contrast to the previously known synergistic action of TF and DnaK/DnaJ above 30°C, a tig null mutation partially suppresses the Cs phenotype exhibited by a compromised DnaK/DnaJ chaperone machine. The antagonistic role of TF is further exemplified by the fact that the secB dnaJ double mutant is viable only in the absence of TF. Finally, we show that, in the absence of TF, more SecA and ribosomes are associated with the inner membrane, suggesting that the presence of TF directly or indirectly interferes with the process of cotranslational protein targeting to the Sec translocon. PMID:17360615
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Uchimura, Tomoya; Hollander, Judith M; Nakamura, Daisy S; Liu, Zhiyi; Rosen, Clifford J; Georgakoudi, Irene; Zeng, Li
2017-10-01
Postnatal bone growth involves a dramatic increase in length and girth. Intriguingly, this period of growth is independent of growth hormone and the underlying mechanism is poorly understood. Recently, an IGF2 mutation was identified in humans with early postnatal growth restriction. Here, we show that IGF2 is essential for longitudinal and appositional murine postnatal bone development, which involves proper timing of chondrocyte maturation and perichondrial cell differentiation and survival. Importantly, the Igf2 null mouse model does not represent a simple delay of growth but instead uncoordinated growth plate development. Furthermore, biochemical and two-photon imaging analyses identified elevated and imbalanced glucose metabolism in the Igf2 null mouse. Attenuation of glycolysis rescued the mutant phenotype of premature cartilage maturation, thereby indicating that IGF2 controls bone growth by regulating glucose metabolism in chondrocytes. This work links glucose metabolism with cartilage development and provides insight into the fundamental understanding of human growth abnormalities. © 2017. Published by The Company of Biologists Ltd.
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Bosher, J M; Dufourcq, P; Sookhareea, S; Labouesse, M
1999-01-01
In nematodes, flies, trypanosomes, and planarians, introduction of double-stranded RNA results in sequence-specific inactivation of gene function, a process termed RNA interference (RNAi). We demonstrate that RNAi against the Caenorhabditis elegans gene lir-1, which is part of the lir-1/lin-26 operon, induced phenotypes very different from a newly isolated lir-1 null mutation. Specifically, lir-1(RNAi) induced embryonic lethality reminiscent of moderately strong lin-26 alleles, whereas the lir-1 null mutant was viable. We show that the lir-1(RNAi) phenotypes resulted from a severe loss of lin-26 gene expression. In addition, we found that RNAi directed against lir-1 or lin-26 introns induced similar phenotypes, so we conclude that lir-1(RNAi) targets the lir-1/lin-26 pre-mRNA. This provides direct evidence that RNA interference can prevent gene expression by targeting nuclear transcripts. Our results highlight that caution may be necessary when interpreting RNA interference without the benefit of mutant alleles. PMID:10545456
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Keratin 17 null mice exhibit age- and strain-dependent alopecia
McGowan, Kevin M.; Tong, Xuemei; Colucci-Guyon, Emma; Langa, Francina; Babinet, Charles; Coulombe, Pierre A.
2002-01-01
Onset of type I keratin 17 (K17) synthesis marks the adoption of an appendageal fate within embryonic ectoderm, and its expression persists in specific cell types within mature hair, glands, and nail. We report that K17 null mice develop severe alopecia during the first week postbirth, correlating with hair fragility, alterations in follicular histology, and apoptosis in matrix cells. These alterations are incompletely penetrant and normalize starting with the first postnatal cycle. Absence of a hair phenotype correlates with a genetic strain-dependent compensation by related keratins, including K16. These findings reveal a crucial role for K17 in the structural integrity of the first hair produced and the survival of hair-producing cells. Given that identical inherited mutations in this gene can cause either pachyonychia congenita or steatocystoma multiplex, the features of this mouse model suggest that this clinical heterogeneity arises from a cell type-specific, genetically determined compensation by related keratins. PMID:12050118
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Combined glutathione S transferase M1/T1 null genotypes is associated with type 2 diabetes mellitus
POROJAN, MIHAI D.; BALA, CORNELIA; ILIES, ROXANA; CATANA, ANDREEA; POPP, RADU A.; DUMITRASCU, DAN L.
2015-01-01
Background Due to new genetic insights, a considerably large number of genes and polymorphic gene variants are screened and linked with the complex pathogenesis of type 2 diabetes (DM). Our study aimed to investigate the association between the two isoforms of the glutathione S-transferase genes (Glutathione S transferase isoemzyme type M1- GSTM1 and Glutathione S transferase isoemzyme type T1-GSTT1) and the prevalence of DM in the Northern Romanian population. Methods We conducted a cross-sectional, randomized, case-control study evaluating the frequency of GSTM1 and GSTT1 null alleles in patients diagnosed with DM. A total of 106 patients diagnosed with DM and 124 healthy controls were included in the study. GSTM1 and GSTT1 null alleles genotyping was carried out using Multiplex PCR amplification of relevant gene fragments, followed by gel electrophoresis analysis of the resulting amplicons. Results Molecular analysis did not reveal an increased frequency of the null GSTM1 and GSTT1 alleles (mutant genotypes) respectively in the DM group compared to controls (p=0.171, OR=1.444 CI=0.852–2.447; p=0.647, OR=0.854, CI=0.436–1.673). Nevertheless, the combined GSTM1/GSTT1 null genotypes were statistically significantly higher in DM patients compared to control subjects (p=0.0021, OR=0.313, CI=0.149–0.655) Conclusions The main finding of our study is that the combined, double GSTM1/GSTT1 null genotypes are to be considered among the polymorphic genetic risk factors for type 2 DM. PMID:26528065
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Liu, Yan; Mo, Lan; Goldfarb, David S.; Evan, Andrew P.; Liang, Fengxia; Khan, Saeed R.; Lieske, John C.
2010-01-01
Mammalian urine contains a range of macromolecule proteins that play critical roles in renal stone formation, among which Tamm-Horsfall protein (THP) is by far the most abundant. While THP is a potent inhibitor of crystal aggregation in vitro and its ablation in vivo predisposes one of the two existing mouse models to spontaneous intrarenal calcium crystallization, key controversies remain regarding the role of THP in nephrolithiasis. By carrying out a long-range follow-up of more than 250 THP-null mice and their wild-type controls, we demonstrate here that renal calcification is a highly consistent phenotype of the THP-null mice that is age and partially gene dosage dependent, but is gender and genetic background independent. Renal calcification in THP-null mice is progressive, and by 15 mo over 85% of all the THP-null mice develop spontaneous intrarenal crystals. The crystals consist primarily of calcium phosphate in the form of hydroxyapatite, are located more frequently in the interstitial space of the renal papillae than intratubularly, particularly in older animals, and lack accompanying inflammatory cell infiltration. The interstitial deposits of hydroxyapatite observed in THP-null mice bear strong resemblances to the renal crystals found in human kidneys bearing idiopathic calcium oxalate stones. Compared with 24-h urine from the wild-type mice, that of THP-null mice is supersaturated with brushite (calcium phosphate), a stone precursor, and has reduced urinary excretion of citrate, a stone inhibitor. While less frequent than renal calcinosis, renal pelvic and ureteral stones and hydronephrosis occur in the aged THP-null mice. These results provide direct in vivo evidence indicating that normal THP plays an important role in defending the urinary system against calcification and suggest that reduced expression and/or decreased function of THP could contribute to nephrolithiasis. PMID:20591941
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Atopic eczema and the filaggrin story.
Brown, Sara J; Irvine, Alan D
2008-06-01
The discovery that null mutations in the filaggrin gene (FLG) are associated with atopic eczema represents the single most significant breakthrough in understanding the genetic basis of this complex disorder. The association has been replicated in multiple independent studies during the past 2 years with the use of various methodologies, from populations in Europe, the United States, and Japan. Filaggrin plays a key role in epidermal barrier function, and its association with atopic eczema emphasizes the importance of barrier dysfunction in eczema pathogenesis. This review aims to summarize the current state of knowledge regarding the role of FLG mutations in ichthyosis vulgaris, atopic eczema, and other skin disorders, with an emphasis on potential clinical applications. Further research is needed to clarify the precise role of filaggrin in skin and systemic atopic disease, to pave the way for novel therapeutic interventions.
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One remarkable molecule: Filaggrin
Brown, Sara J.; McLean, W. H. Irwin
2011-01-01
The discovery, in 2006, that loss-of-function mutations in the filaggrin gene (FLG) are the cause of ichthyosis vulgaris – the most common disorder of keratinization – and also a strong genetic risk factor for atopic eczema, marked a significant breakthrough in the understanding of eczema pathogenesis. Subsequent investigations of the role of FLG null mutations have identified a series of significant associations with atopic disease phenotypes, including atopic asthma, allergic rhinitis and peanut allergy. However, many questions remain to be answered in relation to the precise mechanisms by which deficiency of an intracellular protein expressed primarily in the differentiating epidermis may contribute to the development of cutaneous and systemic pathology. This review aims to highlight the key milestones in filaggrin research over the past 25 years, to discuss the mechanistic, clinical and therapeutic implications and to consider possible future directions for ongoing investigation. PMID:22158554
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Cao, Shang; Bendall, Heather; Hicks, Geoffrey G; Nashabi, Abudi; Sakano, Hitoshi; Shinkai, Yoichi; Gariglio, Marisa; Oltz, Eugene M; Ruley, H Earl
2003-08-01
The high-mobility-group (HMG) SSRP1 protein is a member of a conserved chromatin-remodeling complex (FACT/DUF/CP) implicated in DNA replication, basal and regulated transcription, and DNA repair. To assist in the functional analysis of SSRP1, the Ssrp1 gene was targeted in murine embryonic stem cells, and the mutation was introduced into the germ line. Embryos homozygous for the targeted allele die soon after implantation, and preimplantation blastocysts are defective for cell outgrowth and/or survival in vitro. The Ssrp1 mutation was also crossed into a p53 null background without affecting growth and/or survival defects caused by loss of Ssrp1 function. Thus, Ssrp1 appears to encode nonredundant and p53-independent functions that are essential for cell viability.
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Suppression of gain-of-function mutant p53 with metabolic inhibitors reduces tumor growth in vivo
Jung, Chae Lim; Mun, Hyemin; Jo, Se-Young; Oh, Ju-Hee; Lee, ChuHee; Choi, Eun-Kyung; Jang, Se Jin; Suh, Young-Ah
2016-01-01
Mutation of p53 occasionally results in a gain of function, which promotes tumor growth. We asked whether destabilizing the gain-of-function protein would kill tumor cells. Downregulation of the gene reduced cell proliferation in p53-mutant cells, but not in p53-null cells, indicating that the former depended on the mutant protein for survival. Moreover, phenformin and 2-deoxyglucose suppressed cell growth and simultaneously destabilized mutant p53. The AMPK pathway, MAPK pathway, chaperone proteins and ubiquitination all contributed to this process. Interestingly, phenformin and 2-deoxyglucose also reduced tumor growth in syngeneic mice harboring the p53 mutation. Thus, destabilizing mutant p53 protein in order to kill cells exhibiting “oncogene addiction” could be a promising strategy for combatting p53 mutant tumors. PMID:27765910
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Suppression of gain-of-function mutant p53 with metabolic inhibitors reduces tumor growth in vivo.
Jung, Chae Lim; Mun, Hyemin; Jo, Se-Young; Oh, Ju-Hee; Lee, ChuHee; Choi, Eun-Kyung; Jang, Se Jin; Suh, Young-Ah
2016-11-22
Mutation of p53 occasionally results in a gain of function, which promotes tumor growth. We asked whether destabilizing the gain-of-function protein would kill tumor cells. Downregulation of the gene reduced cell proliferation in p53-mutant cells, but not in p53-null cells, indicating that the former depended on the mutant protein for survival. Moreover, phenformin and 2-deoxyglucose suppressed cell growth and simultaneously destabilized mutant p53. The AMPK pathway, MAPK pathway, chaperone proteins and ubiquitination all contributed to this process. Interestingly, phenformin and 2-deoxyglucose also reduced tumor growth in syngeneic mice harboring the p53 mutation. Thus, destabilizing mutant p53 protein in order to kill cells exhibiting "oncogene addiction" could be a promising strategy for combatting p53 mutant tumors.
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NASA Astrophysics Data System (ADS)
Hotamisligil, Gokhan S.; Johnson, Randall S.; Distel, Robert J.; Ellis, Ramsey; Papaioannou, Virginia E.; Spiegelman, Bruce M.
1996-11-01
Fatty acid binding proteins (FABPs) are small cytoplasmic proteins that are expressed in a highly tissue-specific manner and bind to fatty acids such as oleic and retinoic acid. Mice with a null mutation in aP2, the gene encoding the adipocyte FABP, were developmentally and metabolically normal. The aP2-deficient mice developed dietary obesity but, unlike control mice, they did not develop insulin resistance or diabetes. Also unlike their obese wild-type counterparts, obese aP2-/- animals failed to express in adipose tissue tumor necrosis factor-α (TNF-α), a molecule implicated in obesity-related insulin resistance. These results indicate that aP2 is central to the pathway that links obesity to insulin resistance, possibly by linking fatty acid metabolism to expression of TNF-α.
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[Genetic analysis of two children patients affected with CHARGE syndrome].
Li, Guoqiang; Li, Niu; Xu, Yufei; Li, Juan; Ding, Yu; Shen, Yiping; Wang, Xiumin; Wang, Jian
2018-04-10
To analyze two Chinese pediatric patients with multiple malformations and growth and development delay. Both patients were subjected to targeted gene sequencing, and the results were analyzed with Ingenuity Variant Analysis software. Suspected pathogenic variations were verified by Sanger sequencing. High-throughput sequencing showed that both patients have carried heterozygous variants of the CHD7 gene. Patient 1 carried a nonsense mutation in exon 36 (c.7957C>T, p.Arg2653*), while patient 2 carried a nonsense mutation of exon 2 (c.718C>T, p.Gln240*). Sanger sequencing confirmed the above mutations in both patients, while their parents were of wild-type for the corresponding sites, indicating that the two mutations have happened de novo. Two patients were diagnosed with CHARGE syndrome by high-throughput sequencing.
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De Stefano, Valerio; Za, Tommaso; Rossi, Elena; Vannucchi, Alessandro M; Ruggeri, Marco; Elli, Elena; Micò, Caterina; Tieghi, Alessia; Cacciola, Rossella R; Santoro, Cristina; Vianelli, Nicola; Guglielmelli, Paola; Pieri, Lisa; Scognamiglio, Francesca; Cacciola, Emma; Rodeghiero, Francesco; Pogliani, Enrico M; Finazzi, Guido; Gugliotta, Luigi; Leone, Giuseppe; Barbui, Tiziano
2010-02-01
Evidence suggests that the JAK2 V617F mutation is associated with an increased risk of first thrombosis in patients with essential thrombocythemia (ET). Whether this mutation is also a risk factor for recurrent thrombosis is currently unknown. To investigate the impact of the JAK2 V617F mutation on the risk of recurrent thrombosis in patients with ET, we carried out a multicentre retrospective cohort study. We recruited 143 patients with previous arterial (64.4%) or venous major thrombosis (34.8%) or both (0.8%); 98 of them (68.5%) carried the mutation. Thrombosis recurred in 43 of the patients (30%); overall, after adjustment for sex, age, presence of vascular risk factors, and treatment after the first thrombosis, the presence of the JAK2 mutation did not predict recurrence (multivariable hazard ratio, HR, 0.88, 95% CI 0.46-1.68). Indeed, the individuals homozygous for the JAK2 V617F (allele burden >50%) mutation had an increased risk of recurrence in comparison with wild-type patients (HR 6.15, 95% CI 1.51-24.92). In conclusion, a homozygous JAK2 V617F mutation is an independent risk factor for recurrent thrombosis in patients with ET.
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NASA Astrophysics Data System (ADS)
Goldstein, Janna; Veitch, John; Sesana, Alberto; Vecchio, Alberto
2018-04-01
Super-massive black hole binaries are expected to produce a gravitational wave (GW) signal in the nano-Hertz frequency band which may be detected by pulsar timing arrays (PTAs) in the coming years. The signal is composed of both stochastic and individually resolvable components. Here we develop a generic Bayesian method for the analysis of resolvable sources based on the construction of `null-streams' which cancel the part of the signal held in common for each pulsar (the Earth-term). For an array of N pulsars there are N - 2 independent null-streams that cancel the GW signal from a particular sky location. This method is applied to the localisation of quasi-circular binaries undergoing adiabatic inspiral. We carry out a systematic investigation of the scaling of the localisation accuracy with signal strength and number of pulsars in the PTA. Additionally, we find that source sky localisation with the International PTA data release one is vastly superior than what is achieved by its constituent regional PTAs.
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Quarta, Davide; Naylor, Christopher G; Barik, Jacques; Fernandes, Cathy; Wonnacott, Susan; Stolerman, Ian P
2009-04-01
The nicotine discriminative stimulus has been linked to beta2-containing (beta2*) nicotinic receptors, with little evidence of a role for alpha7 nicotinic receptors, because nicotine discrimination was very weak in beta2 null mutant mice but normal in alpha7 mutants. As both alpha7 and beta2* nicotinic receptors have been implicated in nicotine-stimulated dopamine overflow, this study focused on the dopamine-mediated element in the nicotine stimulus by examining cross-generalisation between amphetamine and nicotine. Male alpha7 nicotinic receptor null mutant mice and wild-type controls were bred in-house and trained to discriminate nicotine (0.8 mg/kg) or (+)-amphetamine (0.6 mg/kg) from saline in a two-lever procedure with a tandem VI-30 FR-10 schedule of food reinforcement. Dopamine release from striatal slices was determined in parallel experiments. An alpha7 nicotinic receptor-mediated component of dopamine release was demonstrated in tissue from wild-type mice using choline as a selective agonist. This response was absent in tissue from null mutant animals. The mutation did not influence acquisition of drug discriminations but subtly affected the results of cross-generalisation tests. In mice trained to discriminate nicotine or amphetamine, there was partial cross-generalisation in wild-type mice and, at certain doses, these effects were attenuated in mutants. Further support for an alpha7 nicotinic receptor-mediated component was provided by the ability of the alpha7 nicotinic receptor antagonist methyllycaconitine to attenuate responses to nicotine and amphetamine in wild-type mice. These findings support the concept of an alpha7 nicotinic receptor-mediated dopaminergic element in nicotine discrimination, warranting further tests with selective dopamine agonists.
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Autism-Relevant Social Abnormalities and Cognitive Deficits in Engrailed-2 Knockout Mice
Brielmaier, Jennifer; Matteson, Paul G.; Silverman, Jill L.; Senerth, Julia M.; Kelly, Samantha; Genestine, Matthieu; Millonig, James H.
2012-01-01
ENGRAILED 2 (En2), a homeobox transcription factor, functions as a patterning gene in the early development and connectivity of rodent hindbrain and cerebellum, and regulates neurogenesis and development of monoaminergic pathways. To further understand the neurobiological functions of En2, we conducted neuroanatomical expression profiling of En2 wildtype mice. RTQPCR assays demonstrated that En2 is expressed in adult brain structures including the somatosensory cortex, hippocampus, striatum, thalamus, hypothalamus and brainstem. Human genetic studies indicate that EN2 is associated with autism. To determine the consequences of En2 mutations on mouse behaviors, including outcomes potentially relevant to autism, we conducted comprehensive phenotyping of social, communication, repetitive, and cognitive behaviors. En2 null mutants exhibited robust deficits in reciprocal social interactions as juveniles and adults, and absence of sociability in adults, replicated in two independent cohorts. Fear conditioning and water maze learning were impaired in En2 null mutants. High immobility in the forced swim test, reduced prepulse inhibition, mild motor coordination impairments and reduced grip strength were detected in En2 null mutants. No genotype differences were found on measures of ultrasonic vocalizations in social contexts, and no stereotyped or repetitive behaviors were observed. Developmental milestones, general health, olfactory abilities, exploratory locomotor activity, anxiety-like behaviors and pain responses did not differ across genotypes, indicating that the behavioral abnormalities detected in En2 null mutants were not attributable to physical or procedural confounds. Our findings provide new insight into the role of En2 in complex behaviors and suggest that disturbances in En2 signaling may contribute to neuropsychiatric disorders marked by social and cognitive deficits, including autism spectrum disorders. PMID:22829897
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Suetsugu, Noriyuki; Kong, Sam-Geun; Kasahara, Masahiro; Wada, Masamitsu
2013-01-01
Phototropins (phot) are blue light receptor proteins that mediate phototropism and control photomovement responses, such as chloroplast photorelocation movement and stomatal opening. Arabidopsis thaliana has two phototropins, phot1 and phot2. Although both phot1 and phot2 redundantly mediate photomovement responses, phot2 uniquely regulates phototropism and the chloroplast avoidance response under high-intensity blue light. However, compared to that of phot1, the mechanistic basis of phot2 function is poorly understood, and in particular, the importance of the LOV2 domain in phot2 function has not been clearly demonstrated. Indeed, photocycle-deficient LOV2 transgenic lines expressing phot2 in a phot1phot2 mutant background retained phototropism, although with less sensitivity than wild-type plants. We isolated 11 alleles of phot2 mutants and determined the molecular lesion in each allele. We analyzed hypocotyl phototropism, chloroplast photorelocation movement, and leaf flattening in the phot2 mutant and the respective phot1phot2 double mutant plants. We demonstrated that unlike the phot2 null mutant, the phot2-10 mutant, which has the defective phot2 LOV2 domain, retained the phototropic response and had unusual chloroplast movement. Mutants phot2-2 and phot2-6, which have a missense mutation in the kinase activation loop of phot2, had the phot2-null mutant phenotype. Furthermore, we convincingly demonstrated that the commonly used phot2-1 mutant allele is a phot2-null mutant. The analyses of the multiple phot2 mutant alleles provided strong evidence for the importance of both LOV domains and the kinase activation loop of phot2 in phototropism and other phot-dependent responses and also demonstrated that phot2-1 allele is a null mutant.
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Diamond, Spencer; Rubin, Benjamin E.; Shultzaberger, Ryan K.; Chen, You; Barber, Chase D.; Golden, Susan S.
2017-01-01
Cyanobacteria evolved a robust circadian clock, which has a profound influence on fitness and metabolism under daily light–dark (LD) cycles. In the model cyanobacterium Synechococcus elongatus PCC 7942, a functional clock is not required for diurnal growth, but mutants defective for the response regulator that mediates transcriptional rhythms in the wild-type, regulator of phycobilisome association A (RpaA), cannot be cultured under LD conditions. We found that rpaA-null mutants are inviable after several hours in the dark and compared the metabolomes of wild-type and rpaA-null strains to identify the source of lethality. Here, we show that the wild-type metabolome is very stable throughout the night, and this stability is lost in the absence of RpaA. Additionally, an rpaA mutant accumulates excessive reactive oxygen species (ROS) during the day and is unable to clear it during the night. The rpaA-null metabolome indicates that these cells are reductant-starved in the dark, likely because enzymes of the primary nighttime NADPH-producing pathway are direct targets of RpaA. Because NADPH is required for processes that detoxify ROS, conditional LD lethality likely results from inability of the mutant to activate reductant-requiring pathways that detoxify ROS when photosynthesis is not active. We identified second-site mutations and growth conditions that suppress LD lethality in the mutant background that support these conclusions. These results provide a mechanistic explanation as to why rpaA-null mutants die in the dark, further connect the clock to metabolism under diurnal growth, and indicate that RpaA likely has important unidentified functions during the day. PMID:28074036
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Alterations in the cholinergic system of brain stem neurons in a mouse model of Rett syndrome.
Oginsky, Max F; Cui, Ningren; Zhong, Weiwei; Johnson, Christopher M; Jiang, Chun
2014-09-15
Rett syndrome is an autism-spectrum disorder resulting from mutations to the X-linked gene, methyl-CpG binding protein 2 (MeCP2), which causes abnormalities in many systems. It is possible that the body may develop certain compensatory mechanisms to alleviate the abnormalities. The norepinephrine system originating mainly in the locus coeruleus (LC) is defective in Rett syndrome and Mecp2-null mice. LC neurons are subject to modulation by GABA, glutamate, and acetylcholine (ACh), providing an ideal system to test the compensatory hypothesis. Here we show evidence for potential compensatory modulation of LC neurons by post- and presynaptic ACh inputs. We found that the postsynaptic currents of nicotinic ACh receptors (nAChR) were smaller in amplitude and longer in decay time in the Mecp2-null mice than in the wild type. Single-cell PCR analysis showed a decrease in the expression of α3-, α4-, α7-, and β3-subunits and an increase in the α5- and α6-subunits in the mutant mice. The α5-subunit was present in many of the LC neurons with slow-decay nAChR currents. The nicotinic modulation of spontaneous GABAA-ergic inhibitory postsynaptic currents in LC neurons was enhanced in Mecp2-null mice. In contrast, the nAChR manipulation of glutamatergic input to LC neurons was unaffected in both groups of mice. Our current-clamp studies showed that the modulation of LC neurons by ACh input was reduced moderately in Mecp2-null mice, despite the major decrease in nAChR currents, suggesting possible compensatory processes may take place, thus reducing the defects to a lesser extent in LC neurons. Copyright © 2014 the American Physiological Society.
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Magalhães, Ana; Gomes, Joana; Ismail, Mohd Nazri; Haslam, Stuart M; Mendes, Nuno; Osório, Hugo; David, Leonor; Le Pendu, Jacques; Haas, Rainer; Dell, Anne; Borén, Thomas; Reis, Celso A
2009-01-01
Glycoconjugates expressed on gastric mucosa play a crucial role in host–pathogen interactions. The FUT2 enzyme catalyzes the addition of terminal α(1,2)fucose residues, producing the H type 1 structure expressed on the surface of epithelial cells and in mucosal secretions of secretor individuals. Inactivating mutations in the human FUT2 gene are associated with reduced susceptibility to Helicobacter pylori infection. H. pylori infects over half the world's population and causes diverse gastric lesions, from gastritis to gastric cancer. H. pylori adhesion constitutes a crucial step in the establishment of a successful infection. The BabA adhesin binds the Leb and H type 1 structures expressed on gastric mucins, while SabA binds to sialylated carbohydrates mediating the adherence to inflamed gastric mucosa. In this study, we have used an animal model of nonsecretors, Fut2-null mice, to characterize the glycosylation profile and evaluate the effect of the observed glycan expression modifications in the process of H. pylori adhesion. We have demonstrated expression of terminal difucosylated glycan structures in C57Bl/6 mice gastric mucosa and that Fut2-null mice showed marked alteration in gastric mucosa glycosylation, characterized by diminished expression of α(1,2)fucosylated structures as indicated by lectin and antibody staining and further confirmed by mass spectrometry analysis. This altered glycosylation profile was further confirmed by the absence of Fucα(1,2)-dependent binding of calicivirus virus-like particles. Finally, using a panel of H. pylori strains, with different adhesin expression profiles, we have demonstated an impairment of BabA-dependent adhesion of H. pylori to Fut2-null mice gastric mucosa, whereas SabA-mediated binding was not affected. PMID:19706747
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Mendelian diseases among Roman Jews: implications for the origins of disease alleles.
Oddoux, C; Guillen-Navarro, E; Ditivoli, C; Dicave, E; Cilio, M R; Clayton, C M; Nelson, H; Sarafoglou, K; McCain, N; Peretz, H; Seligsohn, U; Luzzatto, L; Nafa, K; Nardi, M; Karpatkin, M; Aksentijevich, I; Kastner, D; Axelrod, F; Ostrer, H
1999-12-01
The Roman Jewish community has been historically continuous in Rome since pre-Christian times and may have been progenitor to the Ashkenazi Jewish community. Despite a history of endogamy over the past 2000 yr, the historical record suggests that there was admixture with Ashkenazi and Sephardic Jews during the Middle Ages. To determine whether Roman and Ashkenazi Jews shared common signature mutations, we tested a group of 107 Roman Jews, representing 176 haploid sets of chromosomes. No mutations were found for Bloom syndrome, BRCA1, BRCA2, Canavan disease, Fanconi anemia complementation group C, or Tay-Sachs disease. Two unrelated individuals were positive for the 3849 + 10C->T cystic fibrosis mutation; one carried the N370S Gaucher disease mutation, and one carried the connexin 26 167delT mutation. Each of these was shown to be associated with the same haplotype of tightly linked microsatellite markers as that found among Ashkenazi Jews. In addition, 14 individuals had mutations in the familial Mediterranean fever gene and three unrelated individuals carried the factor XI type III mutation previously observed exclusively among Ashkenazi Jews. These findings suggest that the Gaucher, connexin 26, and familial Mediterranean fever mutations are over 2000 yr old, that the cystic fibrosis 3849 + 10kb C->T and factor XI type III mutations had a common origin in Ashkenazi and Roman Jews, and that other mutations prevalent among Ashkenazi Jews are of more recent origin.
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Lee, Susan; Parent, Carole A.; Insall, Robert; Firtel, Richard A.
1999-01-01
We have identified a novel Ras-interacting protein from Dictyostelium, RIP3, whose function is required for both chemotaxis and the synthesis and relay of the cyclic AMP (cAMP) chemoattractant signal. rip3 null cells are unable to aggregate and lack receptor activation of adenylyl cyclase but are able, in response to cAMP, to induce aggregation-stage, postaggregative, and cell-type-specific gene expression in suspension culture. In addition, rip3 null cells are unable to properly polarize in a cAMP gradient and chemotaxis is highly impaired. We demonstrate that cAMP stimulation of guanylyl cyclase, which is required for chemotaxis, is reduced ∼60% in rip3 null cells. This reduced activation of guanylyl cyclase may account, in part, for the defect in chemotaxis. When cells are pulsed with cAMP for 5 h to mimic the endogenous cAMP oscillations that occur in wild-type strains, the cells will form aggregates, most of which, however, arrest at the mound stage. Unlike the response seen in wild-type strains, the rip3 null cell aggregates that form under these experimental conditions are very small, which is probably due to the rip3 null cell chemotaxis defect. Many of the phenotypes of the rip3 null cell, including the inability to activate adenylyl cyclase in response to cAMP and defects in chemotaxis, are very similar to those of strains carrying a disruption of the gene encoding the putative Ras exchange factor AleA. We demonstrate that aleA null cells also exhibit a defect in cAMP-mediated activation of guanylyl cyclase similar to that of rip3 null cells. A double-knockout mutant (rip3/aleA null cells) exhibits a further reduction in receptor activation of guanylyl cyclase, and these cells display almost no cell polarization or movement in cAMP gradients. As RIP3 preferentially interacts with an activated form of the Dictyostelium Ras protein RasG, which itself is important for cell movement, we propose that RIP3 and AleA are components of a Ras-regulated pathway involved in integrating chemotaxis and signal relay pathways that are essential for aggregation. PMID:10473630
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Risk assessment of maternally inherited SDHD paraganglioma and phaeochromocytoma.
Burnichon, Nelly; Mazzella, Jean-Michaël; Drui, Delphine; Amar, Laurence; Bertherat, Jérôme; Coupier, Isabelle; Delemer, Brigitte; Guilhem, Isabelle; Herman, Philippe; Kerlan, Véronique; Tabarin, Antoine; Wion, Nelly; Lahlou-Laforet, Khadija; Favier, Judith; Gimenez-Roqueplo, Anne-Paule
2017-02-01
Germline mutations in the SDHD tumour suppressor gene (11q23.1) predispose to phaeochromocytomas and paragangliomas (PPGL) mainly on a paternal transmission. However, PPGL have been recently reported in three carriers of a maternally inherited SDHD mutation. To assess the risk of PPGL occurrence on maternal transmission of SDHD mutation. Pedigrees of 80 SDHD-related families have been reviewed. 35 asymptomatic subjects carrying a maternally transmitted SDHD mutation were identified. 20 of them accepted to benefit from a PPGL imaging screening. A unique histologically proven biochemically negative phaeochromocytoma has been diagnosed in a 35-year-old woman. Molecular investigations carried out on tumour tissue revealed that the loss of heterozygosity encompassed the paternally derived q arm and the maternally derived p arm of chromosome 11. This study demonstrates that the risk of developing PPGL for a subject carrying a germline SDHD mutation on the maternal allele remains a rare scenario but does exist. Our data suggest an adjustment of current genetic counselling and clinical care recommendations for at-risk subjects. A targeted familial genetic test should be proposed from the age of 18 years to every subject having a mother carrying a germline SDHD mutation and a first medical workup, including imaging, should be recommended to SDHD-positive mutation carriers. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
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Sun, Shuwen; Guo, Xia; Zhu, Yiping; Yang, Xue; Li, Qiang; Gao, Ju
2014-10-01
To analyze mutations in a pedigree of familial hemophagocytic lymphohistiocytosis (FHLH) from Sichuan and provide genetic counseling for the family. Clinical data of a case with FHLH diagnosed at West China Second Hospital was retrospectively analyzed. Genomic DNA was extracted from peripheral blood samples of the proband and his family members. Eight candidate genes for primary HLH were amplified with PCR and analyzed by direct sequencing. The proband was diagnosed as HLH based on clinical manifestations of recurrent fever for 2 months, hepatosplenomegaly, lymphadenopathy, pancytopenia, hyperferritinemia, and decreased fibrinogen and hemophagocytosis in bone marrow. Genetic testing for primary HLH was carried out considering the relapse of illness after hormone therapy for 8 weeks and the family history. The results of gene sequencing showed that the proband has carried compound heterozygous mutations in PRF1 gene (c.1349C> T in exon 3 and c.445G> A in exon 2). His father has carried a heterozygous mutation (c.445G> A in exon 2) and nonsense mutation (c.900C> T in exon 3), and his mother carried a heterozygous mutation (c.1349C> T in exon 3). Both c.1349C> T and c.445G> A have been previously reported as pathogenic mutations. The family has been diagnosed as familial HLH type 2 based on clinical and laboratory examinations and molecular genetic testing. Gene sequencing has indicated that is was a recessive type familial HLH.
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... child is a son or daughter. How gene mutations cause cancer The genes affected in Lynch syndrome ... children have a risk of inheriting your genetic mutations. If one parent carries a genetic mutation for ...
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Fossat, Nicolas; Ip, Chi Kin; Jones, Vanessa J; Studdert, Joshua B; Khoo, Poh-Lynn; Lewis, Samara L; Power, Melinda; Tourle, Karin; Loebel, David A F; Kwan, Kin Ming; Behringer, Richard R; Tam, Patrick P L
2015-06-01
Lhx1 encodes a LIM homeobox transcription factor that is expressed in the primitive streak, mesoderm and anterior mesendoderm of the mouse embryo. Using a conditional Lhx1 flox mutation and three different Cre deleters, we demonstrated that LHX1 is required in the anterior mesendoderm, but not in the mesoderm, for formation of the head. LHX1 enables the morphogenetic movement of cells that accompanies the formation of the anterior mesendoderm, in part through regulation of Pcdh7 expression. LHX1 also regulates, in the anterior mesendoderm, the transcription of genes encoding negative regulators of WNT signalling, such as Dkk1, Hesx1, Cer1 and Gsc. Embryos carrying mutations in Pcdh7, generated using CRISPR-Cas9 technology, and embryos without Lhx1 function specifically in the anterior mesendoderm displayed head defects that partially phenocopied the truncation defects of Lhx1-null mutants. Therefore, disruption of Lhx1-dependent movement of the anterior mesendoderm cells and failure to modulate WNT signalling both resulted in the truncation of head structures. Compound mutants of Lhx1, Dkk1 and Ctnnb1 show an enhanced head truncation phenotype, pointing to a functional link between LHX1 transcriptional activity and the regulation of WNT signalling. Collectively, these results provide comprehensive insight into the context-specific function of LHX1 in head formation: LHX1 enables the formation of the anterior mesendoderm that is instrumental for mediating the inductive interaction with the anterior neuroectoderm and LHX1 also regulates the expression of factors in the signalling cascade that modulate the level of WNT activity. © 2015. Published by The Company of Biologists Ltd.
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Monoallelic Mutations to DNAJB11 Cause Atypical Autosomal-Dominant Polycystic Kidney Disease.
Cornec-Le Gall, Emilie; Olson, Rory J; Besse, Whitney; Heyer, Christina M; Gainullin, Vladimir G; Smith, Jessica M; Audrézet, Marie-Pierre; Hopp, Katharina; Porath, Binu; Shi, Beili; Baheti, Saurabh; Senum, Sarah R; Arroyo, Jennifer; Madsen, Charles D; Férec, Claude; Joly, Dominique; Jouret, François; Fikri-Benbrahim, Oussamah; Charasse, Christophe; Coulibaly, Jean-Marie; Yu, Alan S; Khalili, Korosh; Pei, York; Somlo, Stefan; Le Meur, Yannick; Torres, Vicente E; Harris, Peter C
2018-05-03
Autosomal-dominant polycystic kidney disease (ADPKD) is characterized by the progressive development of kidney cysts, often resulting in end-stage renal disease (ESRD). This disorder is genetically heterogeneous with ∼7% of families genetically unresolved. We performed whole-exome sequencing (WES) in two multiplex ADPKD-like pedigrees, and we analyzed a further 591 genetically unresolved, phenotypically similar families by targeted next-generation sequencing of 65 candidate genes. WES identified a DNAJB11 missense variant (p.Pro54Arg) in two family members presenting with non-enlarged polycystic kidneys and a frameshifting change (c.166_167insTT) in a second family with small renal and liver cysts. DNAJB11 is a co-factor of BiP, a key chaperone in the endoplasmic reticulum controlling folding, trafficking, and degradation of secreted and membrane proteins. Five additional multigenerational families carrying DNAJB11 mutations were identified by the targeted analysis. The clinical phenotype was consistent in the 23 affected members, with non-enlarged cystic kidneys that often evolved to kidney atrophy; 7 subjects reached ESRD from 59 to 89 years. The lack of kidney enlargement, histologically evident interstitial fibrosis in non-cystic parenchyma, and recurring episodes of gout (one family) suggested partial phenotypic overlap with autosomal-dominant tubulointerstitial diseases (ADTKD). Characterization of DNAJB11-null cells and kidney samples from affected individuals revealed a pathogenesis associated with maturation and trafficking defects involving the ADPKD protein, PC1, and ADTKD proteins, such as UMOD. DNAJB11-associated disease is a phenotypic hybrid of ADPKD and ADTKD, characterized by normal-sized cystic kidneys and progressive interstitial fibrosis resulting in late-onset ESRD. Copyright © 2018 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.
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EMG1 is essential for mouse pre-implantation embryo development.
Wu, Xiaoli; Sandhu, Sumit; Patel, Nehal; Triggs-Raine, Barbara; Ding, Hao
2010-09-21
Essential for mitotic growth 1 (EMG1) is a highly conserved nucleolar protein identified in yeast to have a critical function in ribosome biogenesis. A mutation in the human EMG1 homolog causes Bowen-Conradi syndrome (BCS), a developmental disorder characterized by severe growth failure and psychomotor retardation leading to death in early childhood. To begin to understand the role of EMG1 in mammalian development, and how its deficiency could lead to Bowen-Conradi syndrome, we have used mouse as a model. The expression of Emg1 during mouse development was examined and mice carrying a null mutation for Emg1 were generated and characterized. Our studies indicated that Emg1 is broadly expressed during early mouse embryonic development. However, in late embryonic stages and during postnatal development, Emg1 exhibited specific expression patterns. To assess a developmental role for EMG1 in vivo, we exploited a mouse gene-targeting approach. Loss of EMG1 function in mice arrested embryonic development prior to the blastocyst stage. The arrested Emg1-/- embryos exhibited defects in early cell lineage-specification as well as in nucleologenesis. Further, loss of p53, which has been shown to rescue some phenotypes resulting from defects in ribosome biogenesis, failed to rescue the Emg1-/- pre-implantation lethality. Our data demonstrate that Emg1 is highly expressed during mouse embryonic development, and essential for mouse pre-implantation development. The absolute requirement for EMG1 in early embryonic development is consistent with its essential role in yeast. Further, our findings also lend support to the previous study that showed Bowen-Conradi syndrome results from a partial EMG1 deficiency. A complete deficiency would not be expected to be compatible with a live birth.
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Wang, Yun; Wang, Shunchang; Luo, Xun; Yang, Yanan; Jian, Fenglei; Wang, Xuemin; Xie, Lucheng
2014-08-01
The induction of apoptosis is recognized to be a major mechanism of tributyltin (TBT) toxicity. However, the underlying signaling pathways for TBT-induced apoptosis remain unclear. In this study, using the nematode Caenorhabditis elegans, we examined whether DNA damage response (DDR) pathway and mitogen-activated protein kinase (MAPK) signaling cascades are involved in TBT-induced germline apoptosis and cell cycle arrest. Our results demonstrated that exposing worms to TBT at the dose of 10nM for 6h significantly increased germline apoptosis in N2 strain. Germline apoptosis was absent in strains that carried ced-3 or ced-4 loss-of-function alleles, indicating that both caspase protein CED-3 and Apaf-1 protein CED-4 were required for TBT-induced apoptosis. TBT-induced apoptosis was blocked in the Bcl-2 gain-of-function strain ced-9(n1950), whereas TBT induced a minor increase in the BH3-only protein EGL-1 mutated strain egl-1(n1084n3082). Checkpoint proteins HUS-1 and CLK-2 exerted proapoptotic effects, and the null mutation of cep-1, the homologue of tumor suppressor gene p53, significantly inhibited TBT-induced apoptosis. Apoptosis in the loss-of-function strains of ERK, JNK and p38 MAPK signaling pathways were completely or mildly suppressed under TBT stress. These results were supported by the results of mRNA expression levels of corresponding genes. The present study indicated that TBT-induced apoptosis required the core apoptotic machinery, and that DDR genes and MAPK pathways played essential roles in signaling the processes. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Croxatto, Antony; Chalker, Victoria J.; Lauritz, Johan; Jass, Jana; Hardman, Andrea; Williams, Paul; Cámara, Miguel; Milton, Debra L.
2002-01-01
Vibrio anguillarum possesses at least two N-acylhomoserine lactone (AHL) quorum-sensing circuits, one of which is related to the luxMN system of Vibrio harveyi. In this study, we have cloned an additional gene of this circuit, vanT, encoding a V. harveyi LuxR-like transcriptional regulator. A V. anguillarum ΔvanT null mutation resulted in a significant decrease in total protease activity due to loss of expression of the metalloprotease EmpA, but no changes in either AHL production or virulence. Additional genes positively regulated by VanT were identified from a plasmid-based gene library fused to a promoterless lacZ. Three lacZ fusions (serA::lacZ, hpdA-hgdA::lacZ, and sat-vps73::lacZ) were identified which exhibited decreased expression in the ΔvanT strain. SerA is similar to 3-phosphoglycerate dehydrogenases and catalyzes the first step in the serine-glycine biosynthesis pathway. HgdA has identity with homogentisate dioxygenases, and HpdA is homologous to 4-hydroxyphenylpyruvate dioxygenases (HPPDs) involved in pigment production. V. anguillarum strains require an active VanT to produce high levels of an l-tyrosine-induced brown color via HPPD, suggesting that VanT controls pigment production. Vps73 and Sat are related to Vibrio cholerae proteins encoded within a DNA locus required for biofilm formation. A V. anguillarum ΔvanT mutant and a mutant carrying a polar mutation in the sat-vps73 DNA locus were shown to produce defective biofilms. Hence, a new member of the V. harveyi LuxR transcriptional activator family has been characterized in V. anguillarum that positively regulates serine, metalloprotease, pigment, and biofilm production. PMID:11872713
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Croxatto, Antony; Chalker, Victoria J; Lauritz, Johan; Jass, Jana; Hardman, Andrea; Williams, Paul; Cámara, Miguel; Milton, Debra L
2002-03-01
Vibrio anguillarum possesses at least two N-acylhomoserine lactone (AHL) quorum-sensing circuits, one of which is related to the luxMN system of Vibrio harveyi. In this study, we have cloned an additional gene of this circuit, vanT, encoding a V. harveyi LuxR-like transcriptional regulator. A V. anguillarum Delta vanT null mutation resulted in a significant decrease in total protease activity due to loss of expression of the metalloprotease EmpA, but no changes in either AHL production or virulence. Additional genes positively regulated by VanT were identified from a plasmid-based gene library fused to a promoterless lacZ. Three lacZ fusions (serA::lacZ, hpdA-hgdA::lacZ, and sat-vps73::lacZ) were identified which exhibited decreased expression in the Delta vanT strain. SerA is similar to 3-phosphoglycerate dehydrogenases and catalyzes the first step in the serine-glycine biosynthesis pathway. HgdA has identity with homogentisate dioxygenases, and HpdA is homologous to 4-hydroxyphenylpyruvate dioxygenases (HPPDs) involved in pigment production. V. anguillarum strains require an active VanT to produce high levels of an L-tyrosine-induced brown color via HPPD, suggesting that VanT controls pigment production. Vps73 and Sat are related to Vibrio cholerae proteins encoded within a DNA locus required for biofilm formation. A V. anguillarum Delta vanT mutant and a mutant carrying a polar mutation in the sat-vps73 DNA locus were shown to produce defective biofilms. Hence, a new member of the V. harveyi LuxR transcriptional activator family has been characterized in V. anguillarum that positively regulates serine, metalloprotease, pigment, and biofilm production.
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Cole, Christopher B.; Russler-Germain, David A.; Ketkar, Shamika; Verdoni, Angela M.; Smith, Amanda M.; Bangert, Celia V.; Helton, Nichole M.; Guo, Mindy; O’Laughlin, Shelly; Fronick, Catrina; Fulton, Robert; Chang, Gue Su; Petti, Allegra A.; Miller, Christopher A.; Ley, Timothy J.
2017-01-01
The gene that encodes de novo DNA methyltransferase 3A (DNMT3A) is frequently mutated in acute myeloid leukemia genomes. Point mutations at position R882 have been shown to cause a dominant negative loss of DNMT3A methylation activity, but 15% of DNMT3A mutations are predicted to produce truncated proteins that could either have dominant negative activities or cause loss of function and haploinsufficiency. Here, we demonstrate that 3 of these mutants produce truncated, inactive proteins that do not dimerize with WT DNMT3A, strongly supporting the haploinsufficiency hypothesis. We therefore evaluated hematopoiesis in mice heterozygous for a constitutive null Dnmt3a mutation. With no other manipulations, Dnmt3a+/– mice developed myeloid skewing over time, and their hematopoietic stem/progenitor cells exhibited a long-term competitive transplantation advantage. Dnmt3a+/– mice also spontaneously developed transplantable myeloid malignancies after a long latent period, and 3 of 12 tumors tested had cooperating mutations in the Ras/MAPK pathway. The residual Dnmt3a allele was neither mutated nor downregulated in these tumors. The bone marrow cells of Dnmt3a+/– mice had a subtle but statistically significant DNA hypomethylation phenotype that was not associated with gene dysregulation. These data demonstrate that haploinsufficiency for Dnmt3a alters hematopoiesis and predisposes mice (and probably humans) to myeloid malignancies by a mechanism that is not yet clear. PMID:28872462
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Vazquez Fonseca, Luis; Doimo, Mara; Calderan, Cristina; Desbats, Maria Andrea; Acosta, Manuel J.; Cerqua, Cristina; Cassina, Matteo; Ashraf, Shazia; Hildebrandt, Friedhelm; Sartori, Geppo; Navas, Placido; Trevisson, Eva
2017-01-01
Abstract Mutations in COQ8B cause steroid‐resistant nephrotic syndrome with variable neurological involvement. In yeast, COQ8 encodes a protein required for coenzyme Q (CoQ) biosynthesis, whose precise role is not clear. Humans harbor two paralog genes: COQ8A and COQ8B (previously termed ADCK3 and ADCK4). We have found that COQ8B is a mitochondrial matrix protein peripherally associated with the inner membrane. COQ8B can complement a ΔCOQ8 yeast strain when its mitochondrial targeting sequence (MTS) is replaced by a yeast MTS. This model was employed to validate COQ8B mutations, and to establish genotype–phenotype correlations. All mutations affected respiratory growth, but there was no correlation between mutation type and the severity of the phenotype. In fact, contrary to the case of COQ2, where residual CoQ biosynthesis correlates with clinical severity, patients harboring hypomorphic COQ8B alleles did not display a different phenotype compared with those with null mutations. These data also suggest that the system is redundant, and that other proteins (probably COQ8A) may partially compensate for the absence of COQ8B. Finally, a COQ8B polymorphism, present in 50% of the European population (NM_024876.3:c.521A > G, p.His174Arg), affects stability of the protein and could represent a risk factor for secondary CoQ deficiencies or for other complex traits. PMID:29194833
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Mutations in ABCR (ABCA4) in patients with Stargardt macular degeneration or cone-rod degeneration.
Briggs, C E; Rucinski, D; Rosenfeld, P J; Hirose, T; Berson, E L; Dryja, T P
2001-09-01
To determine the spectrum of ABCR mutations associated with Stargardt macular degeneration and cone-rod degeneration (CRD). One hundred eighteen unrelated patients with recessive Stargardt macular degeneration and eight with recessive CRD were screened for mutations in ABCR (ABCA4) by single-strand conformation polymorphism analysis. Variants were characterized by direct genomic sequencing. Segregation analysis was performed on the families of 20 patients in whom at least two or more likely pathogenic sequence changes were identified. The authors found 77 sequence changes likely to be pathogenic: 21 null mutations (15 novel), 55 missense changes (26 novel), and one deletion of a consensus glycosylation site (also novel). Fifty-two patients with Stargardt macular degeneration (44% of those screened) and five with CRD each had two of these sequence changes or were homozygous for one of them. Segregation analyses in the families of 19 of these patients were informative and revealed that the index cases and all available affected siblings were compound heterozygotes or homozygotes. The authors found one instance of an apparently de novo mutation, Ile824Thr, in a patient. Thirty-seven (31%) of the 118 patients with Stargardt disease and one with CRD had only one likely pathogenic sequence change. Twenty-nine patients with Stargardt disease (25%) and two with CRD had no identified sequence changes. This report of 42 novel mutations brings the growing number of identified likely pathogenic sequence changes in ABCR to approximately 250.
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Slowly progressive retinitis pigmentosa caused by two novel mutations in the MAK gene.
Gray, Joanna Monika; Orlans, Harry Otway; Shanks, Morag; Clouston, Penny; MacLaren, Robert Elvis
2018-05-21
The growing number of clinical trials currently underway for inherited retinal diseases has highlighted the importance of achieving a molecular diagnosis for all new cases presenting to hospital eye services. The male germ cell-associated kinase (MAK) gene encodes a cilium-associated protein selectively expressed in the retina and testis, and has recently been implicated in autosomal recessive retinitis pigmentosa (RP). Whole exome sequencing has previously identified a homozygous Alu insertion in probands with recessive RP and nonsense and missense mutations have also been reported. Here we describe two novel mutations in different alleles of the MAK gene in a 75-year-old British female, who had a clinical diagnosis of RP () with onset in the fourth decade and no relevant family history. The mutations were established through next generation sequencing of a panel of 111 genes associated with RP and RP-like phenotypes. Two novel null mutations were identified within the MAK gene. The first c.1195_1196delAC p.(Thr399fs), was a two base-pair deletion creating a frame-shift in exon 9 predicted to result in nonsense-mediated decay. The second, c.279-2A>G, involved the splice acceptor consensus site upstream of exon 4, predicted to lead to aberrant splicing. The natural history of this individual's RP is consistent with previously described MAK mutations, being significantly milder than that associated with other photoreceptor ciliopathies. We suggest inclusion of MAK as part of wider genetic testing in all individuals presenting with RP.
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The Landscape of Somatic Chromosomal Copy Number Aberrations in GEM Models of Prostate Carcinoma
Bianchi-Frias, Daniella; Hernandez, Susana A.; Coleman, Roger; Wu, Hong; Nelson, Peter S.
2015-01-01
Human prostate cancer (PCa) is known to harbor recurrent genomic aberrations consisting of chromosomal losses, gains, rearrangements and mutations that involve oncogenes and tumor suppressors. Genetically engineered mouse (GEM) models have been constructed to assess the causal role of these putative oncogenic events and provide molecular insight into disease pathogenesis. While GEM models generally initiate neoplasia by manipulating a single gene, expression profiles of GEM tumors typically comprise hundreds of transcript alterations. It is unclear whether these transcriptional changes represent the pleiotropic effects of single oncogenes, and/or cooperating genomic or epigenomic events. Therefore, it was determined if structural chromosomal alterations occur in GEM models of PCa and whether the changes are concordant with human carcinomas. Whole genome array-based comparative genomic hybridization (CGH) was used to identify somatic chromosomal copy number aberrations (SCNAs) in the widely used TRAMP, Hi-Myc, Pten-null and LADY GEM models. Interestingly, very few SCNAs were identified and the genomic architecture of Hi-Myc, Pten-null and LADY tumors were essentially identical to the germline. TRAMP neuroendocrine carcinomas contained SCNAs, which comprised three recurrent aberrations including a single copy loss of chromosome 19 (encoding Pten). In contrast, cell lines derived from the TRAMP, Hi-Myc, and Pten-null tumors were notable for numerous SCNAs that included copy gains of chromosome 15 (encoding Myc) and losses of chromosome 11 (encoding p53). PMID:25298407
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New phenotypes generated by the G57R mutation of BUD23 in Saccharomyces cerevisiae.
Lin, Jyun-Liang; Yu, Hui-Chia; Chao, Ju-Lan; Wang, Chung; Cheng, Ming-Yuan
2012-12-01
BUD23 in Saccharomyces cerevisiae encodes for a class I methyltransferase, and deletion of the gene results in slow growth and random budding phenotypes. Herein, two BUD23 mutants defective in methyltransferase activity were generated to investigate whether the phenotypes of the null mutant might be correlated with a loss in enzymatic activity. Expression at the physiological level of both D77A and G57R mutants was able to rescue the phenotypes of the bud23-null mutant. The result implied that the methyltransferase activity of the protein was not necessary for supporting normal growth and bud site selection of the cells. High-level expression of Bud23 (G57R), but not Bud23 or Bud23 (D77A), in BUD23 deletion cells failed to complement these phenotypes. However, just like Bud23, Bud23 (G57R) was localized in a DAPI-poor region in the nucleus. Distinct behaviour in Bud23 (G57R) could not be originated from a mislocalization of the protein. Over-expression of Bud23 (G57R) in null cells also produced changes in actin organization and additional septin mutant-like phenotypes. Therefore, the absence of Bud23, Bud23 (G57R) at a high level might affect the cell division of yeast cells through an as yet unidentified mechanism. Copyright © 2012 John Wiley & Sons, Ltd.
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Chelh, Ilham; Meunier, Bruno; Picard, Brigitte; Reecy, Mark James; Chevalier, Catherine; Hocquette, Jean-François; Cassar-Malek, Isabelle
2009-01-01
Background Myostatin (MSTN), a member of the TGF-β superfamily, has been identified as a negative regulator of skeletal muscle mass. Inactivating mutations in the MSTN gene are responsible for the development of a hypermuscular phenotype. In this study, we performed transcriptomic and proteomic analyses to detect altered expression/abundance of genes and proteins. These differentially expressed genes and proteins may represent new molecular targets of MSTN and could be involved in the regulation of skeletal muscle mass. Results Transcriptomic analysis of the Quadriceps muscles of 5-week-old MSTN-null mice (n = 4) and their controls (n = 4) was carried out using microarray (human and murine oligonucleotide sequences) of 6,473 genes expressed in muscle. Proteomic profiles were analysed using two-dimensional gel electrophoresis coupled with mass spectrometry. Comparison of the transcriptomic profiles revealed 192 up- and 245 down- regulated genes. Genes involved in the PI3K pathway, insulin/IGF pathway, carbohydrate metabolism and apoptosis regulation were up-regulated. Genes belonging to canonical Wnt, calcium signalling pathways and cytokine-receptor cytokine interaction were down-regulated. Comparison of the protein profiles revealed 20 up- and 18 down-regulated proteins spots. Knockout of the MSTN gene was associated with up-regulation of proteins involved in glycolytic shift of the muscles and down-regulation of proteins involved in oxidative energy metabolism. In addition, an increased abundance of survival/anti-apoptotic factors were observed. Conclusion All together, these results showed a differential expression of genes and proteins related to the muscle energy metabolism and cell survival/anti-apoptotic pathway (e.g. DJ-1, PINK1, 14-3-3ε protein, TCTP/GSK-3β). They revealed the PI3K and apoptotic pathways as MSTN targets and are in favour of a role of MSTN as a modulator of cell survival in vivo. PMID:19397818
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Thiel, Christian T. ; Mortier, Geert ; Kaitila, Ilkka ; Reis, André ; Rauch, Anita
2007-01-01
Mutations in the RMRP gene lead to a wide spectrum of autosomal recessive skeletal dysplasias, ranging from the milder phenotypes metaphyseal dysplasia without hypotrichosis and cartilage hair hypoplasia (CHH) to the severe anauxetic dysplasia (AD). This clinical spectrum includes different degrees of short stature, hair hypoplasia, defective erythrogenesis, and immunodeficiency. The RMRP gene encodes the untranslated RNA component of the mitochondrial RNA–processing ribonuclease, RNase MRP. We recently demonstrated that mutations may affect both messenger RNA (mRNA) and ribosomal RNA (rRNA) cleavage and thus cell-cycle regulation and protein synthesis. To investigate the genotype-phenotype correlation, we analyzed the position and the functional effect of 13 mutations in patients with variable features of the CHH-AD spectrum. Those at the end of the spectrum include a novel patient with anauxetic dysplasia who was compound heterozygous for the null mutation g.254_263delCTCAGCGCGG and the mutation g.195C→T, which was previously described in patients with milder phenotypes. Mapping of nucleotide conservation to the two-dimensional structure of the RMRP gene revealed that disease-causing mutations either affect evolutionarily conserved nucleotides or are likely to alter secondary structure through mispairing in stem regions. In vitro testing of RNase MRP multiprotein-specific mRNA and rRNA cleavage of different mutations revealed a strong correlation between the decrease in rRNA cleavage in ribosomal assembly and the degree of bone dysplasia, whereas reduced mRNA cleavage, and thus cell-cycle impairment, predicts the presence of hair hypoplasia, immunodeficiency, and hematological abnormalities and thus increased cancer risk. PMID:17701897
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Magoulas, Pilar L; El-Hattab, Ayman W; Roy, Angshumoy; Bali, Deeksha S; Finegold, Milton J; Craigen, William J
2012-06-01
Glycogen storage disease type IV is a rare autosomal recessive disorder of glycogen metabolism caused by mutations in the GBE1 gene that encodes the 1,4-alpha-glucan-branching enzyme 1. Its clinical presentation is variable, with the most common form presenting in early childhood with primary hepatic involvement. Histologic manifestations in glycogen storage disease type IV typically consist of intracytoplasmic non-membrane-bound inclusions containing abnormally branched glycogen (polyglucosan bodies) within hepatocytes and myocytes. We report a female infant with classic hepatic form of glycogen storage disease type IV who demonstrated diffuse reticuloendothelial system involvement with the spleen, bone marrow, and lymph nodes infiltrated by foamy histiocytes with intracytoplasmic polyglucosan deposits. Sequence analysis of the GBE1 gene revealed compound heterozygosity for a previously described frameshift mutation (c.1239delT) and a novel missense mutation (c.1279G>A) that is predicted to alter a conserved glycine residue. GBE enzyme analysis revealed no detectable activity. A review of the literature for glycogen storage disease type IV patients with characterized molecular defects and deficient enzyme activity reveals most GBE1 mutations to be missense mutations clustering in the catalytic enzyme domain. Individuals with the classic hepatic form of glycogen storage disease type IV tend to be compound heterozygotes for null and missense mutations. Although the extensive reticuloendothelial system involvement that was observed in our patient is not typical of glycogen storage disease type IV, it may be associated with severe enzymatic deficiency and a poor outcome. Copyright © 2012 Elsevier Inc. All rights reserved.
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Vazquez Fonseca, Luis; Doimo, Mara; Calderan, Cristina; Desbats, Maria Andrea; Acosta, Manuel J; Cerqua, Cristina; Cassina, Matteo; Ashraf, Shazia; Hildebrandt, Friedhelm; Sartori, Geppo; Navas, Placido; Trevisson, Eva; Salviati, Leonardo
2018-03-01
Mutations in COQ8B cause steroid-resistant nephrotic syndrome with variable neurological involvement. In yeast, COQ8 encodes a protein required for coenzyme Q (CoQ) biosynthesis, whose precise role is not clear. Humans harbor two paralog genes: COQ8A and COQ8B (previously termed ADCK3 and ADCK4). We have found that COQ8B is a mitochondrial matrix protein peripherally associated with the inner membrane. COQ8B can complement a ΔCOQ8 yeast strain when its mitochondrial targeting sequence (MTS) is replaced by a yeast MTS. This model was employed to validate COQ8B mutations, and to establish genotype-phenotype correlations. All mutations affected respiratory growth, but there was no correlation between mutation type and the severity of the phenotype. In fact, contrary to the case of COQ2, where residual CoQ biosynthesis correlates with clinical severity, patients harboring hypomorphic COQ8B alleles did not display a different phenotype compared with those with null mutations. These data also suggest that the system is redundant, and that other proteins (probably COQ8A) may partially compensate for the absence of COQ8B. Finally, a COQ8B polymorphism, present in 50% of the European population (NM_024876.3:c.521A > G, p.His174Arg), affects stability of the protein and could represent a risk factor for secondary CoQ deficiencies or for other complex traits. © 2017 The Authors. Human Mutation published by Wiley Periodicals, Inc.
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Geier, Christoph B.; Piller, Alexander; Linder, Angela; Sauerwein, Kai M. T.; Eibl, Martha M.; Wolf, Hermann M.
2015-01-01
Loss of function mutations in the recombination activating genes RAG1 and RAG2 have been reported to cause a T-B-NK+ type of severe combined immunodeficiency. In addition identification of hypomorphic mutations in RAG1 and RAG2 has led to an expansion of the spectrum of disease to include Omenn syndrome, early onset autoimmunity, granuloma, chronic cytomegalovirus- or EBV-infection with expansion of gamma/delta T-cells, idiophatic CD4 lymphopenia and a phenotype resembling common variable immunodeficiency. Herein we describe a novel presentation of leaky RAG1 and RAG2 deficiency in two unrelated adult patients with impaired antibody production against bacterial polysaccharide antigens. Clinical manifestation included recurrent pneumonia, sinusitis, otitis media and in one patient recurrent cutaneous vasculitis. Both patients harbored a combination of a null mutation on one allele with a novel hypomorphic RAG1/2 mutation on the other allele. One of these novel mutations affected the start codon of RAG1 and resulted in an aberrant gene and protein expression. The second novel RAG2 mutation leads to a truncated RAG2 protein, lacking the C-terminus with intact core RAG2 and reduced VDJ recombination capacity as previously described in a mouse model. Both patients presented with severely decreased numbers of naïve CD4+ T cells and defective T independent IgG responses to bacterial polysaccharide antigens, while T cell-dependent IgG antibody formation e.g. after tetanus or TBEV vaccination was intact. In conclusion, hypomorphic mutations in genes responsible for SCID should be considered in adults with predominantly antibody deficiency. PMID:26186701
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Capturing the Flatness of a peer-to-peer lending network through random and selected perturbations
NASA Astrophysics Data System (ADS)
Karampourniotis, Panagiotis D.; Singh, Pramesh; Uparna, Jayaram; Horvat, Emoke-Agnes; Szymanski, Boleslaw K.; Korniss, Gyorgy; Bakdash, Jonathan Z.; Uzzi, Brian
Null models are established tools that have been used in network analysis to uncover various structural patterns. They quantify the deviance of an observed network measure to that given by the null model. We construct a null model for weighted, directed networks to identify biased links (carrying significantly different weights than expected according to the null model) and thus quantify the flatness of the system. Using this model, we study the flatness of Kiva, a large international crownfinancing network of borrowers and lenders, aggregated to the country level. The dataset spans the years from 2006 to 2013. Our longitudinal analysis shows that flatness of the system is reducing over time, meaning the proportion of biased inter-country links is growing. We extend our analysis by testing the robustness of the flatness of the network in perturbations on the links' weights or the nodes themselves. Examples of such perturbations are event shocks (e.g. erecting walls) or regulatory shocks (e.g. Brexit). We find that flatness is unaffected by random shocks, but changes after shocks target links with a large weight or bias. The methods we use to capture the flatness are based on analytics, simulations, and numerical computations using Shannon's maximum entropy. Supported by ARL NS-CTA.
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Ben-Rebeh, Imen; Hertecant, Jozef L.; Al-Jasmi, Fatma A.; Aburawi, Hanan E.; Al-Yahyaee, Said A.; Al-Gazali, Lihadh
2012-01-01
Inborn errors of metabolism (IEM) are frequently encountered by physicians in the United Arab Emirates (UAE). However, the mutations underlying a large number of these disorders have not yet been determined. Therefore, the objective of this study was to identify the mutations underlying a number of IEM disorders among UAE residents from both national and expatriate families. A case series of patients from 34 families attending the metabolic clinic at Tawam Hospital were clinically evaluated, and molecular testing was carried out to determine their causative mutations. The mutation analysis was carried out at molecular genetics diagnostic laboratories. Thirty-eight mutations have been identified as responsible for twenty IEM disorders, including in the metabolism of amino acids, lipids, steroids, metal transport and mitochondrial energy metabolism, and lysosomal storage disorders. Nine of the identified mutations are novel, including two missense mutations, three premature stop codons and four splice site mutations. Mutation analysis of IEM disorders in the UAE population has an important impact on molecular diagnosis and genetic counseling for families affected by these disorders. PMID:22106832
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P53 Suppression of Homologous Recombination and Tumorigenesis
2011-01-01
huge strides have been made in the numbers of mice breed and relevant cells collected for the purposes of experiments outlined in the aims below. The PI... breeding colony of R172P, R172H, Wild type and p53 null mice in order to have sufficient numbers of animals to perform the in vivo pun assay. Mouse...Strains and Breeding Cohorts Mice heterozygous for the point mutations p53R172P and p53R172H both on a C57BL/6 genetic background were kindly
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CUL4B ubiquitin ligase in mouse development: a model for human X-linked mental retardation syndrome?
Zhao, Yongchao; Sun, Yi
2012-08-01
CUL4B, a member of the cullin-RING ubiquitin ligase family, is frequently mutated in X-linked mental retardation (XLMR) patients. The study by Liu et al. showed that Cul4b plays an essential developmental role in the extra-embryonic tissues, while it is dispensable in the embryo proper during mouse embryogenesis. Viable Cul4b-null mice provide the first animal model to study neuronal and behavioral deficiencies seen in human CUL4B XLMR patients.
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Lubin, Johnathan W; Tucey, Timothy M; Lundblad, Victoria
2018-01-01
A leading objective in biology is to identify the complete set of activities that each gene performs in vivo In this study, we have asked whether a genetic approach can provide an efficient means of achieving this goal, through the identification and analysis of a comprehensive set of separation-of-function ( sof - ) mutations in a gene. Toward this goal, we have subjected the Saccharomyces cerevisiae EST1 gene, which encodes a regulatory subunit of telomerase, to intensive mutagenesis (with an average coverage of one mutation for every 4.5 residues), using strategies that eliminated those mutations that disrupted protein folding/stability. The resulting set of sof - mutations defined four biochemically distinct activities for the Est1 telomerase protein: two temporally separable steps in telomerase holoenzyme assembly, a telomerase recruitment activity, and a fourth newly discovered regulatory function. Although biochemically distinct, impairment of each of these four different activities nevertheless conferred a common phenotype (critically short telomeres) comparable to that of an est1 -∆ null strain. This highlights the limitations of gene deletions, even for nonessential genes; we suggest that employing a representative set of sof - mutations for each gene in future high- and low-throughput investigations will provide deeper insights into how proteins interact inside the cell. Copyright © 2018 by the Genetics Society of America.
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Collagen VI disorders: Insights on form and function in the extracellular matrix and beyond.
Lamandé, Shireen R; Bateman, John F
2017-12-22
Mutations in the three canonical collagen VI genes, COL6A1, COL6A2 and COL6A3, cause a spectrum of muscle disease from Bethlem myopathy at the mild end to the severe Ullrich congenital muscular dystrophy. Mutations can be either dominant or recessive and the resulting clinical severity is influenced by the way mutations impact the complex collagen VI assembly process. Most mutations are found towards the N-terminus of the triple helical collagenous domain and compromise extracellular microfibril assembly. Outside the triple helix collagen VI is highly polymorphic and discriminating mutations from rare benign changes remains a major diagnostic challenge. Collagen VI deficiency alters extracellular matrix structure and biomechanical properties and leads to increased apoptosis and oxidative stress, decreased autophagy, and impaired muscle regeneration. Therapies that target these downstream consequences have been tested in a collagen VI null mouse and also in small human trials where they show modest clinical efficacy. An important role for collagen VI in obesity, cancer and diabetes is emerging. A major barrier to developing effective therapies is the paucity of information about how collagen VI deficiency in the extracellular matrix signals the final downstream consequences - the receptors involved and the intracellular messengers await further characterization. Copyright © 2017 International Society of Matrix Biology. Published by Elsevier B.V. All rights reserved.
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Dietrich, Daniela; Schmuths, Heike; Lousa, Carine De Marcos; Baldwin, Jocelyn M.; Baldwin, Stephen A.; Baker, Alison; Holdsworth, Michael J.
2009-01-01
COMATOSE (CTS), the Arabidopsis homologue of human Adrenoleukodystrophy protein (ALDP), is required for import of substrates for peroxisomal β-oxidation. A new allelic series and a homology model based on the bacterial ABC transporter, Sav1866, provide novel insights into structure-function relations of ABC subfamily D proteins. In contrast to ALDP, where the majority of mutations result in protein absence from the peroxisomal membrane, all CTS mutants produced stable protein. Mutation of conserved residues in the Walker A and B motifs in CTS nucleotide-binding domain (NBD) 1 resulted in a null phenotype but had little effect in NBD2, indicating that the NBDs are functionally distinct in vivo. Two alleles containing mutations in NBD1 outside the Walker motifs (E617K and C631Y) exhibited resistance to auxin precursors 2,4-dichlorophenoxybutyric acid (2,4-DB) and indole butyric acid (IBA) but were wild type in all other tests. The homology model predicted that the transmission interfaces are domain-swapped in CTS, and the differential effects of mutations in the conserved “EAA motif” of coupling helix 2 supported this prediction, consistent with distinct roles for each NBD. Our findings demonstrate that CTS functions can be separated by mutagenesis and the structural model provides a framework for interpretation of phenotypic data. PMID:19019987
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Li, Hong; Sheridan, Ryan; Williams, Trevor
2013-01-01
Multiple lines of evidence indicate that the AP-2 transcription factor family has an important regulatory function in human craniofacial development. Notably, mutations in TFAP2A, the gene encoding AP-2α, have been identified in patients with Branchio-Oculo-Facial Syndrome (BOFS). BOFS is an autosomal-dominant trait that commonly presents with facial clefting, eye defects and branchial skin anomalies. Examination of multiple cases has suggested either simple haploinsufficiency or more complex genetic causes for BOFS, especially as the clinical manifestations are variable, with no clear genotype–phenotype correlation. Mutations occur throughout TFAP2A, but mostly within conserved sequences within the DNA contact domain of AP-2α. However, the consequences of the various mutations for AP-2α protein function have not been evaluated. Therefore, it remains unclear if all BOFS mutations result in similar changes to the AP-2α protein or if they each produce specific alterations that underlie the spectrum of phenotypes. Here, we have investigated the molecular consequences of the mutations that localize to the DNA-binding region. We show that although individual mutations have different effects on DNA binding, they all demonstrate significantly reduced transcriptional activities. Moreover, all mutant derivatives have an altered nuclear:cytoplasmic distribution compared with the predominantly nuclear localization of wild-type AP-2α and several can exert a dominant-negative activity on the wild-type AP-2α protein. Overall, our data suggest that the individual TFAP2A BOFS mutations can generate null, hypomorphic or antimorphic alleles and that these differences in activity, combined with a role for AP-2α in epigenetic events, may influence the resultant pathology and the phenotypic variability. PMID:23578821
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Marez, D; Legrand, M; Sabbagh, N; Lo Guidice, J M; Spire, C; Lafitte, J J; Meyer, U A; Broly, F
1997-06-01
The polymorphic cytochrome P450 CYP2D6 is involved in the metabolism of various drugs of wide therapeutic use and is a presumed susceptibility factor for certain environmentally-induced diseases. Our aim was to define the mutations and alleles of the CYP2D6 gene and to evaluate their frequencies in the European population. Using polymerase chain reaction-single strand conformation polymorphism analysis, 672 unrelated subjects were screened for mutations in the 9 exons of the gene and their exon-intron boundaries. A total of 48 point mutations were identified, of which 29 were novel. Mutations 1749 G-->C, 2938 C-->T and 4268 G-->C represented 52.6%, 34.3% and 52.9% of the mutations in the total population, respectively. Of the eight detrimental mutations detected, the 1934 G-->A, the 1795 Tdel and the 2637 Adel accounted for 65.8%, 6.2% and 4.8% respectively, within the poor metabolizer subgroup. Fifty-three different alleles were characterized from the mutation pattern and by allele-specific sequencing. They are derived from three major alleles, namely the wild-type CYP2D6*1A, the functional CYP2D6*2 and the null CYP2D6*4A. Five allelic variants (CYP2D6*1A, *2, *2B, *4A and *5) account for about 87% of all alleles, while the remaining alleles occur with a frequency of 0.1%-2.7%. These data provide a solid basis for future epidemiological, clinical as well as interethnic studies of the CYP2D6 polymorphism and highlight that the described single strand conformation polymorphism method can be successfully used in designing such studies.
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Stephen, Joshi; Nampoothiri, Sheela; Banerjee, Aditi; Tolman, Nathanial J; Penninger, Josef Martin; Elling, Ullrich; Agu, Chukwuma A; Burke, John D; Devadathan, Kalpana; Kannan, Rajesh; Huang, Yan; Steinbach, Peter J; Martinis, Susan A; Gahl, William A; Malicdan, May Christine V
2018-04-01
Progressive microcephaly and neurodegeneration are genetically heterogenous conditions, largely associated with genes that are essential for the survival of neurons. In this study, we interrogate the genetic etiology of two siblings from a non-consanguineous family with severe early onset of neurological manifestations. Whole exome sequencing identified novel compound heterozygous mutations in VARS that segregated with the proband: a missense (c.3192G>A; p.Met1064Ile) and a splice site mutation (c.1577-2A>G). The VARS gene encodes cytoplasmic valyl-tRNA synthetase (ValRS), an enzyme that is essential during eukaryotic translation. cDNA analysis on patient derived fibroblasts revealed that the splice site acceptor variant allele led to nonsense mediated decay, thus resulting in a null allele. Three-dimensional modeling of ValRS predicts that the missense mutation lies in a highly conserved region and could alter side chain packing, thus affecting tRNA binding or destabilizing the interface between the catalytic and tRNA binding domains. Further quantitation of the expression of VARS showed remarkably reduced levels of mRNA and protein in skin derived fibroblasts. Aminoacylation experiments on patient derived cells showed markedly reduced enzyme activity of ValRS suggesting the mutations to be loss of function. Bi-allelic mutations in cytoplasmic amino acyl tRNA synthetases are well-known for their role in neurodegenerative disorders, yet human disorders associated with VARS mutations have not yet been clinically well characterized. Our study describes the phenotype associated with recessive VARS mutations and further functional delineation of the pathogenicity of novel variants identified, which widens the clinical and genetic spectrum of patients with progressive microcephaly.
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Hilton, Emma; Johnston, Jennifer; Whalen, Sandra; Okamoto, Nobuhiko; Hatsukawa, Yoshikazu; Nishio, Juntaro; Kohara, Hiroshi; Hirano, Yoshiko; Mizuno, Seiji; Torii, Chiharu; Kosaki, Kenjiro; Manouvrier, Sylvie; Boute, Odile; Perveen, Rahat; Law, Caroline; Moore, Anthony; Fitzpatrick, David; Lemke, Johannes; Fellmann, Florence; Debray, François-Guillaume; Dastot-Le-Moal, Florence; Gerard, Marion; Martin, Josiane; Bitoun, Pierre; Goossens, Michel; Verloes, Alain; Schinzel, Albert; Bartholdi, Deborah; Bardakjian, Tanya; Hay, Beverly; Jenny, Kim; Johnston, Kathreen; Lyons, Michael; Belmont, John W; Biesecker, Leslie G; Giurgea, Irina; Black, Graeme
2009-01-01
Oculofaciocardiodental (OFCD) and Lenz microphthalmia syndromes form part of a spectrum of X-linked microphthalmia disorders characterized by ocular, dental, cardiac and skeletal anomalies and mental retardation. The two syndromes are allelic, caused by mutations in the BCL-6 corepressor gene (BCOR). To extend the series of phenotypes associated with pathogenic mutations in BCOR, we sequenced the BCOR gene in patients with (1) OFCD syndrome, (2) putative X-linked (‘Lenz') microphthalmia syndrome, (3) isolated ocular defects and (4) laterality phenotypes. We present a new cohort of females with OFCD syndrome and null mutations in BCOR, supporting the hypothesis that BCOR is the sole molecular cause of this syndrome. We identify for the first time mosaic BCOR mutations in two females with OFCD syndrome and one apparently asymptomatic female. We present a female diagnosed with isolated ocular defects and identify minor features of OFCD syndrome, suggesting that OFCD syndrome may be mild and underdiagnosed. We have sequenced a cohort of males diagnosed with putative X-linked microphthalmia and found a mutation, p.P85L, in a single case, suggesting that BCOR mutations are not a major cause of X-linked microphthalmia in males. The absence of BCOR mutations in a panel of patients with non-specific laterality defects suggests that mutations in BCOR are not a major cause of isolated heart and laterality defects. Phenotypic analysis of OFCD and Lenz microphthalmia syndromes shows that in addition to the standard diagnostic criteria of congenital cataract, microphthalmia and radiculomegaly, patients should be examined for skeletal defects, particularly radioulnar synostosis, and cardiac/laterality defects. PMID:19367324
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Biallelic UFM1 and UFC1 mutations expand the essential role of ufmylation in brain development.
Nahorski, Michael S; Maddirevula, Sateesh; Ishimura, Ryosuke; Alsahli, Saud; Brady, Angela F; Begemann, Anaïs; Mizushima, Tsunehiro; Guzmán-Vega, Francisco J; Obata, Miki; Ichimura, Yoshinobu; Alsaif, Hessa S; Anazi, Shams; Ibrahim, Niema; Abdulwahab, Firdous; Hashem, Mais; Monies, Dorota; Abouelhoda, Mohamed; Meyer, Brian F; Alfadhel, Majid; Eyaid, Wafa; Zweier, Markus; Steindl, Katharina; Rauch, Anita; Arold, Stefan T; Woods, C Geoffrey; Komatsu, Masaaki; Alkuraya, Fowzan S
2018-06-02
The post-translational modification of proteins through the addition of UFM1, also known as ufmylation, plays a critical developmental role as revealed by studies in animal models. The recent finding that biallelic mutations in UBA5 (the E1-like enzyme for ufmylation) cause severe early-onset encephalopathy with progressive microcephaly implicates ufmylation in human brain development. More recently, a homozygous UFM1 variant was proposed as a candidate aetiology of severe early-onset encephalopathy with progressive microcephaly. Here, we establish a locus for severe early-onset encephalopathy with progressive microcephaly based on two families, and map the phenotype to a novel homozygous UFM1 mutation. This mutation has a significantly diminished capacity to form thioester intermediates with UBA5 and with UFC1 (the E2-like enzyme for ufmylation), with resulting impaired ufmylation of cellular proteins. Remarkably, in four additional families where eight children have severe early-onset encephalopathy with progressive microcephaly, we identified two biallelic UFC1 mutations, which impair UFM1-UFC1 intermediate formation with resulting widespread reduction of cellular ufmylation, a pattern similar to that observed with UFM1 mutation. The striking resemblance between UFM1- and UFC1-related clinical phenotype and biochemical derangements strongly argues for an essential role for ufmylation in human brain development. The hypomorphic nature of UFM1 and UFC1 mutations and the conspicuous depletion of biallelic null mutations in the components of this pathway in human genome databases suggest that it is necessary for embryonic survival, which is consistent with the embryonic lethal nature of knockout models for the orthologous genes.
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Alsop, Kathryn; Fereday, Sian; Meldrum, Cliff; deFazio, Anna; Emmanuel, Catherine; George, Joshy; Dobrovic, Alexander; Birrer, Michael J.; Webb, Penelope M.; Stewart, Colin; Friedlander, Michael; Fox, Stephen; Bowtell, David; Mitchell, Gillian
2012-01-01
Purpose The frequency of BRCA1 and BRCA2 germ-line mutations in women with ovarian cancer is unclear; reports vary from 3% to 27%. The impact of germ-line mutation on response requires further investigation to understand its impact on treatment planning and clinical trial design. Patients and Methods Women with nonmucinous ovarian carcinoma (n = 1,001) enrolled onto a population-based, case-control study were screened for point mutations and large deletions in both genes. Survival outcomes and responses to multiple lines of chemotherapy were assessed. Results Germ-line mutations were found in 14.1% of patients overall, including 16.6% of serous cancer patients (high-grade serous, 22.6%); 44% had no reported family history of breast or ovarian cancer. Patients carrying germ-line mutations had improved rates of progression-free and overall survival. In the relapse setting, patients carrying mutations more frequently responded to both platin- and nonplatin-based regimens than mutation-negative patients, even in patients with early relapse after primary treatment. Mutation-negative patients who responded to multiple cycles of platin-based treatment were more likely to carry somatic BRCA1/2 mutations. Conclusion BRCA mutation status has a major influence on survival in ovarian cancer patients and should be an additional stratification factor in clinical trials. Treatment outcomes in BRCA1/2 carriers challenge conventional definitions of platin resistance, and mutation status may be able to contribute to decision making and systemic therapy selection in the relapse setting. Our data, together with the advent of poly(ADP-ribose) polymerase inhibitor trials, supports the recommendation that germ-line BRCA1/2 testing should be offered to all women diagnosed with nonmucinous, ovarian carcinoma, regardless of family history. PMID:22711857
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Bartlett, Heather L.; Sutherland, Lillian; Kolker, Sandra J.; Welp, Chelsea; Tajchman, Urszula; Desmarais, Vera; Weeks, Daniel L.
2007-01-01
Nkx2-5 is a homeobox containing transcription factor that is conserved and expressed in organisms that form hearts. Fruit flies lacking the gene (tinman) fail to form a dorsal vessel, mice that are homozygous null for Nkx2-5 form small, deformed hearts, and several human cardiac defects have been linked to dominant mutations in the Nkx2-5 gene. The Xenopus homologs (XNkx2-5) of two truncated forms of Nkx2-5 that have been identified in humans with congenital heart defects were used in the studies reported here. mRNAs encoding these mutations were injected into single cell Xenopus embryos, and heart development was monitored. Our results indicate that the introduction of truncated XNkx2-5 variants leads to three principle developmental defects. The atrial septum and the valve of the atrioventricular canal were both abnormal. In addition, video microscopic timing of heart contraction indicated that embryos injected with either mutant form of XNkx2-5 have conduction defects. PMID:17685485
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Point mutation impairs centromeric CENH3 loading and induces haploid plants.
Karimi-Ashtiyani, Raheleh; Ishii, Takayoshi; Niessen, Markus; Stein, Nils; Heckmann, Stefan; Gurushidze, Maia; Banaei-Moghaddam, Ali Mohammad; Fuchs, Jörg; Schubert, Veit; Koch, Kerstin; Weiss, Oda; Demidov, Dmitri; Schmidt, Klaus; Kumlehn, Jochen; Houben, Andreas
2015-09-08
The chromosomal position of the centromere-specific histone H3 variant CENH3 (also called "CENP-A") is the assembly site for the kinetochore complex of active centromeres. Any error in transcription, translation, modification, or incorporation can affect the ability to assemble intact CENH3 chromatin and can cause centromere inactivation [Allshire RC, Karpen GH (2008) Nat Rev Genet 9 (12):923-937]. Here we show that a single-point amino acid exchange in the centromere-targeting domain of CENH3 leads to reduced centromere loading of CENH3 in barley, sugar beet, and Arabidopsis thaliana. Haploids were obtained after cenh3 L130F-complemented cenh3-null mutant plants were crossed with wild-type A. thaliana. In contrast, in a noncompeting situation (i.e., centromeres possessing only mutated or only wild-type CENH3), no uniparental chromosome elimination occurs during early embryogenesis. The high degree of evolutionary conservation of the identified mutation site offers promising opportunities for application in a wide range of crop species in which haploid technology is of interest.
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Burbulis, I E; Iacobucci, M; Shirley, B W
1996-01-01
Flavonoids are a major class of secondary metabolites that serves a multitude of functions in higher plants, including a recently discovered role in male fertility. Surprisingly, Arabidopsis plants deficient in flavonoid biosynthesis appear to be fully fertile. Using RNA gel blot analysis and polymerase chain reaction-based assays, we have shown that a mutation at the 3' splice acceptor site in the Arabidopsis chalcone synthase gene completely disrupts synthesis of the active form of the enzyme. We also confirmed that this enzyme, which catalyzes the first step of flavonoid biosynthesis, is encoded by a single-copy gene. HPLC analysis of whole flowers and stamens was used to show that plants homozygous for the splice site mutation are completely devoid of flavonoids. This work provides compelling evidence that despite the high levels of these compounds in the pollen of most plant species, flavonoids are not universally required for fertility. The role of flavonoids in plant reproduction may therefore offer an example of convergent functional evolution in secondary metabolism. PMID:8672888
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Point mutation impairs centromeric CENH3 loading and induces haploid plants
Karimi-Ashtiyani, Raheleh; Ishii, Takayoshi; Niessen, Markus; Stein, Nils; Heckmann, Stefan; Gurushidze, Maia; Banaei-Moghaddam, Ali Mohammad; Fuchs, Jörg; Schubert, Veit; Koch, Kerstin; Weiss, Oda; Demidov, Dmitri; Schmidt, Klaus; Kumlehn, Jochen; Houben, Andreas
2015-01-01
The chromosomal position of the centromere-specific histone H3 variant CENH3 (also called “CENP-A”) is the assembly site for the kinetochore complex of active centromeres. Any error in transcription, translation, modification, or incorporation can affect the ability to assemble intact CENH3 chromatin and can cause centromere inactivation [Allshire RC, Karpen GH (2008) Nat Rev Genet 9 (12):923–937]. Here we show that a single-point amino acid exchange in the centromere-targeting domain of CENH3 leads to reduced centromere loading of CENH3 in barley, sugar beet, and Arabidopsis thaliana. Haploids were obtained after cenh3 L130F-complemented cenh3-null mutant plants were crossed with wild-type A. thaliana. In contrast, in a noncompeting situation (i.e., centromeres possessing only mutated or only wild-type CENH3), no uniparental chromosome elimination occurs during early embryogenesis. The high degree of evolutionary conservation of the identified mutation site offers promising opportunities for application in a wide range of crop species in which haploid technology is of interest. PMID:26294252
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Double muscling in cattle due to mutations in the myostatin gene
McPherron, Alexandra C.; Lee, Se-Jin
1997-01-01
Myostatin (GDF-8) is a member of the transforming growth factor β superfamily of secreted growth and differentiation factors that is essential for proper regulation of skeletal muscle mass in mice. Here we report the myostatin sequences of nine other vertebrate species and the identification of mutations in the coding sequence of bovine myostatin in two breeds of double-muscled cattle, Belgian Blue and Piedmontese, which are known to have an increase in muscle mass relative to conventional cattle. The Belgian Blue myostatin sequence contains an 11-nucleotide deletion in the third exon which causes a frameshift that eliminates virtually all of the mature, active region of the molecule. The Piedmontese myostatin sequence contains a missense mutation in exon 3, resulting in a substitution of tyrosine for an invariant cysteine in the mature region of the protein. The similarity in phenotypes of double-muscled cattle and myostatin null mice suggests that myostatin performs the same biological function in these two species and is a potentially useful target for genetic manipulation in other farm animals. PMID:9356471
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Functional repair of p53 mutation in colorectal cancer cells using trans-splicing.
He, Xingxing; Liao, Jiazhi; Liu, Fang; Yan, Junwei; Yan, Jingjun; Shang, Haitao; Dou, Qian; Chang, Ying; Lin, Jusheng; Song, Yuhu
2015-02-10
Mutation in the p53 gene is arguably the most frequent type of gene-specific alterations in human cancers. Current p53-based gene therapy contains the administration of wt-p53 or the suppression of mutant p53 expression in p53-defective cancer cells. . We hypothesized that trans-splicing could be exploited as a tool for the correction of mutant p53 transcripts in p53-mutated human colorectal cancer (CRC) cells. In this study, the plasmids encoding p53 pre-trans-splicing molecules (PTM) were transfected into human CRC cells carrying p53 mutation. The plasmids carrying p53-PTM repaired mutant p53 transcripts in p53-mutated CRC cells, which resulted in a reduction in mutant p53 transcripts and an induction of wt-p53 simultaneously. Intratumoral administration of adenovirus vectors carrying p53 trans-splicing cassettes suppressed the growth of tumor xenografts. Repair of mutant p53 transcripts by trans-splicing induced cell-cycle arrest and apoptosis in p53-defective colorectal cancer cells in vitro and in vivo. In conclusion, the present study demonstrated for the first time that trans-splicing was exploited as a strategy for the repair of mutant p53 transcripts, which revealed that trans-splicing would be developed as a new therapeutic approach for human colorectal cancers carrying p53 mutation.
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Mancini, Irene; Lampronti, Ilaria; Salvatori, Francesca; Fabbri, Enrica; Zuccato, Cristina; Cosenza, Lucia C.; Montagner, Giulia; Borgatti, Monica; Altruda, Fiorella; Fagoonee, Sharmila; Carandina, Gianni; Aiello, Vincenzo; Breda, Laura; Rivella, Stefano; Gambari, Roberto
2015-01-01
Mouse models that carry mutations causing thalassemia represent a suitable tool to test in vivo new mutation-specific therapeutic approaches. Transgenic mice carrying the β-globin IVSI-6 mutation (the most frequent in Middle-Eastern regions and recurrent in Italy and Greece) are, at present, not available. We report the production and characterization of a transgenic mouse line (TG-β-IVSI-6) carrying the IVSI-6 thalassemia point mutation within the human β-globin gene. In the TG-β-IVSI-6 mouse (a) the transgenic integration region is located in mouse chromosome 7; (b) the expression of the transgene is tissue specific; (c) as expected, normally spliced human β-globin mRNA is produced, giving rise to β-globin production and formation of a human-mouse tetrameric chimeric hemoglobin mu α-globin2/hu β-globin2 and, more importantly, (d) the aberrant β-globin-IVSI-6 RNAs are present in blood cells. The TG-β-IVSI-6 mouse reproduces the molecular features of IVSI-6 β-thalassemia and might be used as an in vivo model to characterize the effects of antisense oligodeoxynucleotides targeting the cryptic sites responsible for the generation of aberrantly spliced β-globin RNA sequences, caused by the IVSI-6 mutation. These experiments are expected to be crucial for the development of a personalized therapy for β-thalassemia. PMID:26097845
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JAK2, MPL, and CALR mutations in Chinese Han patients with essential thrombocythemia.
Wang, Jing; Zhang, Biao; Chen, Bing; Zhou, Rong-Fu; Zhang, Qi-Guo; Li, Juan; Yang, Yong-Gong; Zhou, Min; Shao, Xiao-Yan; Xu, Yong; Xu, Xi-Hui; Ouyang, Jian; Xu, Jingyan; Ye, Qing
2017-04-01
Mutations in Janus kinase 2 (JAK2), myeloproliferative leukemia (MPL), and CALR are highly relevant to Philadelphia chromosome (Ph)-negative myeloproliferative neoplasms. Assessing the prevalence of molecular mutations in Chinese Han patients with essential thrombocythemia (ET), and correlating their mutational profile with disease characteristics/phenotype. Of the 110 subjects studied, 62 carried the JAK2 V617F mutation, 21 had CALR mutations, one carried an MPL (W515) mutation, and 28 had non-mutated JAK2, CALR, and MPL (so-called triple-negative ET). Mutations in JAK2 exon 12 were not detected in any patient. Two ET patients had both CALR and JAK2 V617F mutations. Comparing the hematological parameters of the patients with JAK2 mutations with those of the patients with CALR mutations showed that the ET patients with CALR mutations were younger (p = 0.045) and had higher platelet counts (p = 0.043). Genotyping for CALR could be a useful diagnostic tool for JAK2/MPL-negative ET, since the data suggest that CALR is much more prevalent than MPL, therefore testing for CALR should be considered in patients who are JAK2 negative as its frequency is almost 20 times that of MPL mutation.
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Nemoto-Hasebe, I; Akiyama, M; Nomura, T; Sandilands, A; McLean, W H I; Shimizu, H
2009-12-01
Mutations in the gene encoding filaggrin (FLG) have been shown to predispose to atopic eczema (AE). Further to establish population genetics of FLG mutations in the Japanese population and to elucidate effects of FLG mutations to filaggrin biosynthesis in skin of patients with AE. We searched for FLG mutations in 19 newly recruited Japanese patients with AE. We then screened 137 Japanese patients with AE and 134 Japanese control individuals for a novel mutation identified in the present study. In addition, we evaluated FLG mRNA expression by real-time reverse transcription-polymerase chain reaction and profilaggrin/filaggrin protein expression by immunohistochemical staining in the epidermis of the patients carrying the novel mutation. We identified a novel FLG nonsense mutation c.12069A>T (p.Lys4021X) in one patient with AE. Upon further screening, p.Lys4021X was identified in four patients with AE (2.9% of all the patients with AE). In total, there are at least eight FLG variants in the Japanese population. Here we show that about 27% of patients in our Japanese AE case series carry one or more of these eight FLG mutations and these variants are also carried by 3.7% of Japanese general control individuals. There is a significant statistical association between the eight FLG mutations and AE (chi(2) P = 6.50 x 10(-8)). Interestingly, the present nonsense mutation is in the C-terminal incomplete filaggrin repeat and is the mutation nearest the C-terminal among previously reported FLG mutations. Immunohistochemical staining for filaggrin revealed that this nonsense mutation leads to remarkable reduction of filaggrin protein expression in the patients' epidermis. We clearly demonstrated that FLG mutations are significantly associated with AE in the Japanese population. The present results further support the hypothesis that the C-terminal region is essential for proper processing of profilaggrin to filaggrin.
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Wacker, Michael J; Touchberry, Chad D; Silswal, Neerupma; Brotto, Leticia; Elmore, Chris J; Bonewald, Lynda F; Andresen, Jon; Brotto, Marco
2016-01-01
Autosomal recessive hypophosphatemic rickets (ARHR) is a heritable disorder characterized by hypophosphatemia, osteomalacia, and poor bone development. ARHR results from inactivating mutations in the DMP1 gene with the human phenotype being recapitulated in the Dmp1 null mouse model which displays elevated plasma fibroblast growth factor 23. While the bone phenotype has been well-characterized, it is not known what effects ARHR may also have on skeletal, cardiac, or vascular smooth muscle function, which is critical to understand in order to treat patients suffering from this condition. In this study, the extensor digitorum longus (EDL-fast-twitch muscle), soleus (SOL-slow-twitch muscle), heart, and aorta were removed from Dmp1 null mice and ex-vivo functional tests were simultaneously performed in collaboration by three different laboratories. Dmp1 null EDL and SOL muscles produced less force than wildtype muscles after normalization for physiological cross sectional area of the muscles. Both EDL and SOL muscles from Dmp1 null mice also produced less force after the addition of caffeine (which releases calcium from the sarcoplasmic reticulum) which may indicate problems in excitation contraction coupling in these mice. While the body weights of the Dmp1 null were smaller than wildtype, the heart weight to body weight ratio was higher. However, there were no differences in pathological hypertrophic gene expression compared to wildtype and maximal force of contraction was not different indicating that there may not be cardiac pathology under the tested conditions. We did observe a decrease in the rate of force development generated by cardiac muscle in the Dmp1 null which may be related to some of the deficits observed in skeletal muscle. There were no differences observed in aortic contractions induced by PGF2α or 5-HT or in endothelium-mediated acetylcholine-induced relaxations or endothelium-independent sodium nitroprusside-induced relaxations. In summary, these results indicate that there are deficiencies in both fast twitch and slow twitch muscle fiber type contractions in this model of ARHR, while there was less of a phenotype observed in cardiac muscle, and no differences observed in aortic function. These results may help explain skeletal muscle weakness reported by some patients with osteomalacia and need to be further investigated.
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Wacker, Michael J.; Touchberry, Chad D.; Silswal, Neerupma; Brotto, Leticia; Elmore, Chris J.; Bonewald, Lynda F.; Andresen, Jon; Brotto, Marco
2016-01-01
Autosomal recessive hypophosphatemic rickets (ARHR) is a heritable disorder characterized by hypophosphatemia, osteomalacia, and poor bone development. ARHR results from inactivating mutations in the DMP1 gene with the human phenotype being recapitulated in the Dmp1 null mouse model which displays elevated plasma fibroblast growth factor 23. While the bone phenotype has been well-characterized, it is not known what effects ARHR may also have on skeletal, cardiac, or vascular smooth muscle function, which is critical to understand in order to treat patients suffering from this condition. In this study, the extensor digitorum longus (EDL-fast-twitch muscle), soleus (SOL–slow-twitch muscle), heart, and aorta were removed from Dmp1 null mice and ex-vivo functional tests were simultaneously performed in collaboration by three different laboratories. Dmp1 null EDL and SOL muscles produced less force than wildtype muscles after normalization for physiological cross sectional area of the muscles. Both EDL and SOL muscles from Dmp1 null mice also produced less force after the addition of caffeine (which releases calcium from the sarcoplasmic reticulum) which may indicate problems in excitation contraction coupling in these mice. While the body weights of the Dmp1 null were smaller than wildtype, the heart weight to body weight ratio was higher. However, there were no differences in pathological hypertrophic gene expression compared to wildtype and maximal force of contraction was not different indicating that there may not be cardiac pathology under the tested conditions. We did observe a decrease in the rate of force development generated by cardiac muscle in the Dmp1 null which may be related to some of the deficits observed in skeletal muscle. There were no differences observed in aortic contractions induced by PGF2α or 5-HT or in endothelium-mediated acetylcholine-induced relaxations or endothelium-independent sodium nitroprusside-induced relaxations. In summary, these results indicate that there are deficiencies in both fast twitch and slow twitch muscle fiber type contractions in this model of ARHR, while there was less of a phenotype observed in cardiac muscle, and no differences observed in aortic function. These results may help explain skeletal muscle weakness reported by some patients with osteomalacia and need to be further investigated. PMID:27242547
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Littink, Karin W.; Koenekoop, Robert K.; van den Born, L. Ingeborgh; Collin, Rob W. J.; Moruz, Luminita; Veltman, Joris A.; Roosing, Susanne; Zonneveld, Marijke N.; Omar, Amer; Darvish, Mahshad; Lopez, Irma; Kroes, Hester Y.; van Genderen, Maria M.; Hoyng, Carel B.; Rohrschneider, Klaus; van Schooneveld, Mary J.; Cremers, Frans P. M.
2010-01-01
Purpose. To determine the genetic defect and to describe the clinical characteristics in a cohort of mainly nonconsanguineous cone–rod dystrophy (CRD) patients. Methods. One hundred thirty-nine patients with diagnosed CRD were recruited. Ninety of them were screened for known mutations in ABCA4, and those carrying one or two mutations were excluded from further research. Genome-wide homozygosity mapping was performed in the remaining 108. Known genes associated with autosomal recessive retinal dystrophies located within a homozygous region were screened for mutations. Patients in whom a mutation was detected underwent further ophthalmic examination. Results. Homozygous sequence variants were identified in eight CRD families, six of which were nonconsanguineous. The variants were detected in the following six genes: ABCA4, CABP4, CERKL, EYS, KCNV2, and PROM1. Patients carrying mutations in ABCA4, CERKL, and PROM1 had typical CRD symptoms, but a variety of retinal appearances on funduscopy, optical coherence tomography, and autofluorescence imaging. Conclusions. Homozygosity mapping led to the identification of new mutations in consanguineous and nonconsanguineous patients with retinal dystrophy. Detailed clinical characterization revealed a variety of retinal appearances, ranging from nearly normal to extensive retinal remodeling, retinal thinning, and debris accumulation. Although CRD was initially diagnosed in all patients, the molecular findings led to a reappraisal of the diagnosis in patients carrying mutations in EYS, CABP4, and KCNV2. PMID:20554613
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Complete exon sequencing of all known Usher syndrome genes greatly improves molecular diagnosis.
Bonnet, Crystel; Grati, M'hamed; Marlin, Sandrine; Levilliers, Jacqueline; Hardelin, Jean-Pierre; Parodi, Marine; Niasme-Grare, Magali; Zelenika, Diana; Délépine, Marc; Feldmann, Delphine; Jonard, Laurence; El-Amraoui, Aziz; Weil, Dominique; Delobel, Bruno; Vincent, Christophe; Dollfus, Hélène; Eliot, Marie-Madeleine; David, Albert; Calais, Catherine; Vigneron, Jacqueline; Montaut-Verient, Bettina; Bonneau, Dominique; Dubin, Jacques; Thauvin, Christel; Duvillard, Alain; Francannet, Christine; Mom, Thierry; Lacombe, Didier; Duriez, Françoise; Drouin-Garraud, Valérie; Thuillier-Obstoy, Marie-Françoise; Sigaudy, Sabine; Frances, Anne-Marie; Collignon, Patrick; Challe, Georges; Couderc, Rémy; Lathrop, Mark; Sahel, José-Alain; Weissenbach, Jean; Petit, Christine; Denoyelle, Françoise
2011-05-11
Usher syndrome (USH) combines sensorineural deafness with blindness. It is inherited in an autosomal recessive mode. Early diagnosis is critical for adapted educational and patient management choices, and for genetic counseling. To date, nine causative genes have been identified for the three clinical subtypes (USH1, USH2 and USH3). Current diagnostic strategies make use of a genotyping microarray that is based on the previously reported mutations. The purpose of this study was to design a more accurate molecular diagnosis tool. We sequenced the 366 coding exons and flanking regions of the nine known USH genes, in 54 USH patients (27 USH1, 21 USH2 and 6 USH3). Biallelic mutations were detected in 39 patients (72%) and monoallelic mutations in an additional 10 patients (18.5%). In addition to biallelic mutations in one of the USH genes, presumably pathogenic mutations in another USH gene were detected in seven patients (13%), and another patient carried monoallelic mutations in three different USH genes. Notably, none of the USH3 patients carried detectable mutations in the only known USH3 gene, whereas they all carried mutations in USH2 genes. Most importantly, the currently used microarray would have detected only 30 of the 81 different mutations that we found, of which 39 (48%) were novel. Based on these results, complete exon sequencing of the currently known USH genes stands as a definite improvement for molecular diagnosis of this disease, which is of utmost importance in the perspective of gene therapy.
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[Maple syrup urine disease and gene mutations in twin neonates].
Li, Tao; Wang, Yu; Li, Cui; Xu, Wei-Wei; Niu, Feng-Hai; Zhang, Di
2016-12-01
To investigate the clinical features of one pair of twin neonates with maple syrup urine disease (MSUD) in the Chinese Han population and pathogenic mutations in related genes, and to provide guidance for the early diagnosis and treatment of MSUD. The clinical and imaging data of the twin neonates were collected. The peripheral blood samples were collected from the twin neonates and their parents to detect the genes related to MSUD (BCKDHA, BCKDHB, DBT, and DLD). The loci with gene mutations were identified, and a bioinformatic analysis was performed. Two mutations were detected in the BCKDHB gene, missense mutation c.304G>A (p.Gly102Arg) and nonsense mutation c.331C>T (p.Arg111*), and both of them were heterozygotes. The mutation c.304G>A (p.Gly102Arg) had not been reported in the world. Their father carried the missense mutation c.304G>A (p.Gly102Arg), and their mother carried the nonsense mutation c.331C>T (p.Arg111*). The c.331C>T (p.Arg111*) heterozygous mutation in BCKDHB gene is the pathogenic mutation in these twin neonates and provides a genetic and molecular basis for the clinical features of children with MSUD.
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Correction of the Middle Eastern M712T mutation causing GNE myopathy by trans-splicing.
Tal-Goldberg, Tzukit; Lorain, Stéphanie; Mitrani-Rosenbaum, Stella
2014-06-01
GNE myopathy is a rare neuromuscular autosomal recessive disease, resulting from mutations in the gene UDP N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE). The most frequent mutation is the single homozygous missense mutation, M712T-the Middle Eastern mutation-located ten amino acids before the end of the protein. We have used an adeno-associated virus (AAV)-based trans-splicing (TS) vector as a gene therapy tool to overcome this mutation by replacing the mutated last exon of GNE by the wild-type exon while preserving the natural endogenous regulatory machinery. We have designed relevant plasmids directed either to mouse or to human GNE. Following transfection of C2C12 murine muscle cells with the mouse TS vectors, we have been able to detect by nested RT-PCR trans-spliced molecules carrying the wild-type exon 12 of GNE. Similarly, transfection of HEK293 human cells with the human-directed TS vectors resulted in the generation of trans-spliced human GNE RNA molecules. Furthermore, infection of primary muscle cells from a GNE myopathy patient carrying the homozygous M712T mutation, with an AAV8-based viral vector carrying a human-directed TS construct, resulted in the generation of wild-type GNE transcripts in addition to the mutated ones. These studies provide a proof of concept that the TS approach could be used to partially correct the Middle Eastern mutation in GNE myopathy patients. These results provide the basis for in vivo research in animal models using the AAV platform with TS plasmids as a potential genetic therapy for GNE myopathy.
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Schlathölter, Ina; Jänsch, Melanie; Flachowsky, Henryk; Broggini, Giovanni Antonio Lodovico; Hanke, Magda-Viola; Patocchi, Andrea
2018-06-01
The approach presented here can be applied to reduce the time needed to introduce traits from wild apples into null segregant advanced selections by one-fourth. Interesting traits like resistances to pathogens are often found within the wild apple gene pool. However, the long juvenile phase of apple seedlings hampers the rapid introduction of these traits into new cultivars. The rapid crop cycle breeding approach used in this paper is based on the overexpression of the birch (Betula pendula) MADS4 transcription factor in apple. Using the early flowering line T1190 and 'Evereste' as source of the fire blight resistance (Fb_E locus), we successfully established 18 advanced selections of the fifth generation in the greenhouse within 7 years. Fifteen individuals showed the habitus expected of a regular apple seedling, while three showed very short internodes. The null segregants possessing a regular habitus maintained the high level of fire blight resistance typical for 'Evereste'. Using SSR markers, we estimated the percentage of genetic drag from 'Evereste' still associated with Fb_E on linkage group 12 (LG12). Eight out of the 18 selections had only 4% of 'Evereste' genome left. Since genotypes carrying the apple scab resistance gene Rvi6 and the fire blight resistance QTL Fb_F7 were used as parents in the course of the experiments, these resistances were also identified in some of the null segregants. One seedling is particularly interesting as, beside Fb_E, it also carries Fb_F7 heterozygously and Rvi6 homozygously. If null segregants obtained using this method will be considered as not genetically modified in Europe, as is already the case in the USA, this genotype could be a very promising parent for breeding new fire blight and scab-resistant apple cultivars in European apple breeding programs.
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Bracher, Jasmine M; de Hulster, Erik; Koster, Charlotte C; van den Broek, Marcel; Daran, Jean-Marc G; van Maris, Antonius J A; Pronk, Jack T
2017-08-15
Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is extremely slow (specific growth rate [μ] ≈ 0.01 h -1 ). Four independent evolution experiments in repeated batch cultures and accelerostats yielded strains whose growth rates (μ ≤ 0.36 h -1 ) in biotin-free and biotin-supplemented media were similar. Whole-genome resequencing of these evolved strains revealed up to 40-fold amplification of BIO1 , which encodes pimeloyl-coenzyme A (CoA) synthetase. The additional copies of BIO1 were found on different chromosomes, and its amplification coincided with substantial chromosomal rearrangements. A key role of this gene amplification was confirmed by overexpression of BIO1 in strain CEN.PK113-7D, which enabled growth in biotin-free medium (μ = 0.15 h -1 ). Mutations in the membrane transporter genes TPO1 and/or PDR12 were found in several of the evolved strains. Deletion of TPO1 and PDR12 in a BIO1 -overexpressing strain increased its specific growth rate to 0.25 h -1 The effects of null mutations in these genes, which have not been previously associated with biotin metabolism, were nonadditive. This study demonstrates that S. cerevisiae strains that carry the basic genetic information for biotin synthesis can be evolved for full biotin prototrophy and identifies new targets for engineering biotin prototrophy into laboratory and industrial strains of this yeast. IMPORTANCE Although biotin (vitamin H) plays essential roles in all organisms, not all organisms can synthesize this vitamin. Many strains of baker's yeast, an important microorganism in industrial biotechnology, contain at least some of the genes required for biotin synthesis. However, most of these strains cannot synthesize biotin at all or do so at rates that are insufficient to sustain fast growth and product formation. Consequently, this expensive vitamin is routinely added to baker's yeast cultures. In this study, laboratory evolution in biotin-free growth medium yielded new strains that grew as fast in the absence of biotin as in its presence. By analyzing the DNA sequences of evolved biotin-independent strains, mutations were identified that contributed to this ability. This work demonstrates full biotin independence of an industrially relevant yeast and identifies mutations whose introduction into other yeast strains may reduce or eliminate their biotin requirements. Copyright © 2017 American Society for Microbiology.
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de Hulster, Erik; Koster, Charlotte C.; van den Broek, Marcel; van Maris, Antonius J. A.
2017-01-01
ABSTRACT Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is extremely slow (specific growth rate [μ] ≈ 0.01 h−1). Four independent evolution experiments in repeated batch cultures and accelerostats yielded strains whose growth rates (μ ≤ 0.36 h−1) in biotin-free and biotin-supplemented media were similar. Whole-genome resequencing of these evolved strains revealed up to 40-fold amplification of BIO1, which encodes pimeloyl-coenzyme A (CoA) synthetase. The additional copies of BIO1 were found on different chromosomes, and its amplification coincided with substantial chromosomal rearrangements. A key role of this gene amplification was confirmed by overexpression of BIO1 in strain CEN.PK113-7D, which enabled growth in biotin-free medium (μ = 0.15 h−1). Mutations in the membrane transporter genes TPO1 and/or PDR12 were found in several of the evolved strains. Deletion of TPO1 and PDR12 in a BIO1-overexpressing strain increased its specific growth rate to 0.25 h−1. The effects of null mutations in these genes, which have not been previously associated with biotin metabolism, were nonadditive. This study demonstrates that S. cerevisiae strains that carry the basic genetic information for biotin synthesis can be evolved for full biotin prototrophy and identifies new targets for engineering biotin prototrophy into laboratory and industrial strains of this yeast. IMPORTANCE Although biotin (vitamin H) plays essential roles in all organisms, not all organisms can synthesize this vitamin. Many strains of baker's yeast, an important microorganism in industrial biotechnology, contain at least some of the genes required for biotin synthesis. However, most of these strains cannot synthesize biotin at all or do so at rates that are insufficient to sustain fast growth and product formation. Consequently, this expensive vitamin is routinely added to baker's yeast cultures. In this study, laboratory evolution in biotin-free growth medium yielded new strains that grew as fast in the absence of biotin as in its presence. By analyzing the DNA sequences of evolved biotin-independent strains, mutations were identified that contributed to this ability. This work demonstrates full biotin independence of an industrially relevant yeast and identifies mutations whose introduction into other yeast strains may reduce or eliminate their biotin requirements. PMID:28600311
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Leonardis, L; Auer-Grumbach, M; Papić, L; Zidar, J
2012-07-01
Mutations in atlastin-1 (ATL-1), a gene known to cause pure, early-onset autosomal dominant hereditary spastic paraplegia SPG3A, have been recently reported to cause hereditary sensory neuropathy I (HSN I). We describe the detailed clinical and electrophysiologic findings in the first family with ulcero-mutilating sensory neuropathy carrying the c. C1065A, p.N355K mutation in ATL-1. Detailed clinical and electrophysiologic studies were performed in affected and at-risk family members. Motor and sensory nerve conductions studies (NCS) were carried out in upper and lower limbs. ATL-1 was screened for mutations by direct sequencing. Ten patients were found to carry the N355K mutation. With the exception of the two youngest patients, all had trophic skin changes in the feet consisting mainly of painless ulcers. Frequently, amputation of toes, feet, or even more proximal parts of the lower legs became necessary. A variable degree of increased muscle tone was observed in younger patients, whilst some older affected individuals only presented with hyperreflexia of patellar tendon reflexes. NCS revealed signs of an axonal motor and sensory neuropathies. Our family carrying the N355K ATL1 mutation, which was initially diagnosed as HSN I, enlarges the SPG3A phenotype. We therefore suggest that patients with HSN I excluded for more common causes of HSN I, and in particular, affected individuals who exhibit additional pyramidal tract features should also be screened for mutations in ATL1. © 2012 The Author(s) European Journal of Neurology © 2012 EFNS.
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Rosty, Christophe; Clendenning, Mark; Walsh, Michael D; Eriksen, Stine V; Southey, Melissa C; Winship, Ingrid M; Macrae, Finlay A; Boussioutas, Alex; Poplawski, Nicola K; Parry, Susan; Arnold, Julie; Young, Joanne P; Casey, Graham; Haile, Robert W; Gallinger, Steven; Le Marchand, Loïc; Newcomb, Polly A; Potter, John D; DeRycke, Melissa; Lindor, Noralane M; Thibodeau, Stephen N; Baron, John A; Win, Aung Ko; Hopper, John L; Jenkins, Mark A; Buchanan, Daniel D
2016-02-19
Immunohistochemistry for DNA mismatch repair proteins is used to screen for Lynch syndrome in individuals with colorectal carcinoma (CRC). Although solitary loss of PMS2 expression is indicative of carrying a germline mutation in PMS2, previous studies reported MLH1 mutation in some cases. We determined the prevalence of MLH1 germline mutations in a large cohort of individuals with a CRC demonstrating solitary loss of PMS2 expression. This cohort study included 88 individuals affected with a PMS2-deficient CRC from the Colon Cancer Family Registry Cohort. Germline PMS2 mutation analysis (long-range PCR and multiplex ligation-dependent probe amplification) was followed by MLH1 mutation testing (Sanger sequencing and multiplex ligation-dependent probe amplification). Of the 66 individuals with complete mutation screening, we identified a pathogenic PMS2 mutation in 49 (74%), a pathogenic MLH1 mutation in 8 (12%) and a MLH1 variant of uncertain clinical significance predicted to be damaging by in silico analysis in 3 (4%); 6 (9%) carried variants likely to have no clinical significance. Missense point mutations accounted for most alterations (83%; 9/11) in MLH1. The MLH1 c.113A> G p.Asn38Ser mutation was found in 2 related individuals. One individual who carried the MLH1 intronic mutation c.677+3A>G p.Gln197Argfs*8 leading to the skipping of exon 8, developed 2 tumours, both of which retained MLH1 expression. A substantial proportion of CRCs with solitary loss of PMS2 expression are associated with a deleterious MLH1 germline mutation supporting the screening for MLH1 in individuals with tumours of this immunophenotype, when no PMS2 mutation has been identified. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/
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Rosty, Christophe; Clendenning, Mark; Walsh, Michael D; Eriksen, Stine V; Southey, Melissa C; Winship, Ingrid M; Macrae, Finlay A; Boussioutas, Alex; Parry, Susan; Arnold, Julie; Young, Joanne P; Casey, Graham; Haile, Robert W; Gallinger, Steven; Le Marchand, Loïc; Newcomb, Polly A; Potter, John D; DeRycke, Melissa; Lindor, Noralane M; Thibodeau, Stephen N; Baron, John A; Win, Aung Ko; Hopper, John L; Jenkins, Mark A; Buchanan, Daniel D
2016-01-01
Objectives Immunohistochemistry for DNA mismatch repair proteins is used to screen for Lynch syndrome in individuals with colorectal carcinoma (CRC). Although solitary loss of PMS2 expression is indicative of carrying a germline mutation in PMS2, previous studies reported MLH1 mutation in some cases. We determined the prevalence of MLH1 germline mutations in a large cohort of individuals with a CRC demonstrating solitary loss of PMS2 expression. Design This cohort study included 88 individuals affected with a PMS2-deficient CRC from the Colon Cancer Family Registry Cohort. Germline PMS2 mutation analysis (long-range PCR and multiplex ligation-dependent probe amplification) was followed by MLH1 mutation testing (Sanger sequencing and multiplex ligation-dependent probe amplification). Results Of the 66 individuals with complete mutation screening, we identified a pathogenic PMS2 mutation in 49 (74%), a pathogenic MLH1 mutation in 8 (12%) and a MLH1 variant of uncertain clinical significance predicted to be damaging by in silico analysis in 3 (4%); 6 (9%) carried variants likely to have no clinical significance. Missense point mutations accounted for most alterations (83%; 9/11) in MLH1. The MLH1 c.113A> G p.Asn38Ser mutation was found in 2 related individuals. One individual who carried the MLH1 intronic mutation c.677+3A>G p.Gln197Argfs*8 leading to the skipping of exon 8, developed 2 tumours, both of which retained MLH1 expression. Conclusions A substantial proportion of CRCs with solitary loss of PMS2 expression are associated with a deleterious MLH1 germline mutation supporting the screening for MLH1 in individuals with tumours of this immunophenotype, when no PMS2 mutation has been identified. PMID:26895986
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De novo mutations in regulatory elements in neurodevelopmental disorders
Short, Patrick J.; McRae, Jeremy F.; Gallone, Giuseppe; Sifrim, Alejandro; Won, Hyejung; Geschwind, Daniel H.; Wright, Caroline F.; Firth, Helen V; FitzPatrick, David R.; Barrett, Jeffrey C.; Hurles, Matthew E.
2018-01-01
We previously estimated that 42% of patients with severe developmental disorders carry pathogenic de novo mutations in coding sequences. The role of de novo mutations in regulatory elements affecting genes associated with developmental disorders, or other genes, has been essentially unexplored. We identified de novo mutations in three classes of putative regulatory elements in almost 8,000 patients with developmental disorders. Here we show that de novo mutations in highly evolutionarily conserved fetal brain-active elements are significantly and specifically enriched in neurodevelopmental disorders. We identified a significant twofold enrichment of recurrently mutated elements. We estimate that, genome-wide, 1-3% of patients without a diagnostic coding variant carry pathogenic de novo mutations in fetal brain-active regulatory elements and that only 0.15% of all possible mutations within highly conserved fetal brain-active elements cause neurodevelopmental disorders with a dominant mechanism. Our findings represent a robust estimate of the contribution of de novo mutations in regulatory elements to this genetically heterogeneous set of disorders, and emphasize the importance of combining functional and evolutionary evidence to identify regulatory causes of genetic disorders. PMID:29562236
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Bonthius, Daniel J.; Winters, Zachary; Karacay, Bahri; Bousquet, Samantha Larimer; Bonthius, Daniel J.
2014-01-01
The cerebellum is a major target of alcohol-induced damage in the developing brain. However, the cerebella of some children are much more seriously affected than others by prenatal alcohol exposure. As a consequence of in utero alcohol exposure, some children have substantial reductions in cerebellar volume and corresponding neurodevelopmental problems, including microencephaly, ataxia, and balance deficits, while other children who were exposed to similar alcohol quantities are spared. One factor that likely plays a key role in determining the impact of alcohol on the fetal cerebellum is genetics. However, no specific gene variant has yet been identified that worsens cerebellar function as a consequence of developmental alcohol exposure. Previous studies have revealed that mice carrying a homozygous mutation of the gene for neuronal nitric oxide synthase (nNOS−/− mice) have more severe acute alcohol-induced neuronal losses from the cerebellum than wild type mice. Therefore, the goals of this study were to determine whether alcohol induces more severe cerebellum-based behavioral deficits in nNOS−/− mice than in wild type mice and to determine whether these worsened behavior deficits are associated with worsened cerebellar neuronal losses. nNOS−/− mice and their wild type controls received alcohol (0.0, 2.2, or 4.4 mg/g) daily over postnatal days 4–9. In adulthood, the mice underwent behavioral testing, followed by neuronal quantification. Alcohol caused dose-related deficits in rotarod and balance beam performance in both nNOS−/− and wild type mice. However, the alcohol-induced behavioral deficits were substantially worse in the nNOS−/− mice than in wild type. Likewise, alcohol exposure led to losses of Purkinje cells and cerebellar granule cells in mice of both genotypes, but the cell losses were more severe in the nNOS−/− mice than in wild type. Behavioral performances were correlated with neuronal number in the nNOS−/− mice, but not in wild type. Thus, homozygous mutation of the nNOS gene increases vulnerability to alcohol-induced cerebellar dysfunction and neuronal loss. nNOS is the first gene identified whose mutation worsens alcohol-induced cerebellar behavioral deficits. PMID:25511929
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Koukouikila-Koussounda, Felix; Jeyaraj, Sankarganesh; Nguetse, Christian N; Nkonganyi, Charles Nchotebah; Kokou, Kossiwa Clarisse; Etoka-Beka, Mandingha K; Ntoumi, Francine; Velavan, Thirumalaisamy P
2017-04-19
Resistance to anti-malarial drugs hinders efforts on malaria elimination and eradication. Following the global spread of chloroquine-resistant parasites, the Republic of Congo adopted artemisinin-based combination therapy (ACT) in 2006 as a first-line treatment for uncomplicated malaria. To assess the impacts after implementation of ACT, a molecular surveillance for anti-malarial drug resistance was conducted in Congo 4 and 9 years after the introduction of ACT. Blood samples of 431 febrile children aged 1-10 years were utilized from two previous studies conducted in 2010 (N = 311) and 2015 (N = 120). All samples were screened for malaria parasites using nested PCR. Direct sequencing was used to determine the frequency distribution of genetic variants in the anti-malarial drug-resistant Plasmodium falciparum genes (Pfcrt, Pfmdr1, Pfatp6, Pfk13) in malaria-positive isolates. One-hundred and nineteen (N = 70 from 2010 and N = 49 from 2015) samples were positive for P. falciparum. A relative decrease in the proportion of chloroquine-resistant haplotype (CVIET) from 100% in 2005, 1 year before the introduction and implementation of ACT in 2006, to 98% in 2010 to 71% in 2015 was observed. Regarding the multidrug transporter gene, a considerable reduction in the frequency of the mutations N86Y (from 73 to 27%) and D1246Y (from 22 to 0%) was observed. However, the prevalence of the Y184F mutation remained stable (49% in 2010 compared to 54% in 2015). Isolates carrying the Pfatp6 H243Y was 25% in 2010 and this frequency was reduced to null in 2015. None of the parasites harboured the Pfk13 mutations associated with prolonged artemisinin clearance in Southeast Asia. Nevertheless, 13 new Pfk13 variants are reported among the investigated isolates. The implementation of ACT has led to the decline in prevalence of chloroquine-resistant parasites in the Republic of Congo. However, the constant prevalence of the PfMDR1 Y184F mutation, associated with lumefantrine susceptibility, indicate a selective drug pressure still exists. Taken together, this study could serve as the basis for epidemiological studies monitoring the distribution of molecular markers of artemisinin resistance in the Republic of Congo.
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Israeli, Eitan; Dryanovski, Dilyan I.; Schumacker, Paul T.; Chandel, Navdeep S.; Singer, Jeffrey D.; Julien, Jean P.; Goldman, Robert D.; Opal, Puneet
2016-01-01
Intermediate filaments (IFs) are cytoskeletal polymers that extend from the nucleus to the cell membrane, giving cells their shape and form. Abnormal accumulation of IFs is involved in the pathogenesis of number neurodegenerative diseases, but none as clearly as giant axonal neuropathy (GAN), a ravaging disease caused by mutations in GAN, encoding gigaxonin. Patients display early and severe degeneration of the peripheral nervous system along with IF accumulation, but it has been difficult to link GAN mutations to any particular dysfunction, in part because GAN null mice have a very mild phenotype. We therefore established a robust dorsal root ganglion neuronal model that mirrors key cellular events underlying GAN. We demonstrate that gigaxonin is crucial for ubiquitin–proteasomal degradation of neuronal IF. Moreover, IF accumulation impairs mitochondrial motility and is associated with metabolic and oxidative stress. These results have implications for other neurological disorders whose pathology includes IF accumulation. PMID:27000625
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Discovery of cancer drug targets by CRISPR-Cas9 screening of protein domains.
Shi, Junwei; Wang, Eric; Milazzo, Joseph P; Wang, Zihua; Kinney, Justin B; Vakoc, Christopher R
2015-06-01
CRISPR-Cas9 genome editing technology holds great promise for discovering therapeutic targets in cancer and other diseases. Current screening strategies target CRISPR-Cas9-induced mutations to the 5' exons of candidate genes, but this approach often produces in-frame variants that retain functionality, which can obscure even strong genetic dependencies. Here we overcome this limitation by targeting CRISPR-Cas9 mutagenesis to exons encoding functional protein domains. This generates a higher proportion of null mutations and substantially increases the potency of negative selection. We also show that the magnitude of negative selection can be used to infer the functional importance of individual protein domains of interest. A screen of 192 chromatin regulatory domains in murine acute myeloid leukemia cells identifies six known drug targets and 19 additional dependencies. A broader application of this approach may allow comprehensive identification of protein domains that sustain cancer cells and are suitable for drug targeting.
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NKX2-5 regulates human cardiomyogenesis via a HEY2 dependent transcriptional network.
Anderson, David J; Kaplan, David I; Bell, Katrina M; Koutsis, Katerina; Haynes, John M; Mills, Richard J; Phelan, Dean G; Qian, Elizabeth L; Leitoguinho, Ana Rita; Arasaratnam, Deevina; Labonne, Tanya; Ng, Elizabeth S; Davis, Richard P; Casini, Simona; Passier, Robert; Hudson, James E; Porrello, Enzo R; Costa, Mauro W; Rafii, Arash; Curl, Clare L; Delbridge, Lea M; Harvey, Richard P; Oshlack, Alicia; Cheung, Michael M; Mummery, Christine L; Petrou, Stephen; Elefanty, Andrew G; Stanley, Edouard G; Elliott, David A
2018-04-10
Congenital heart defects can be caused by mutations in genes that guide cardiac lineage formation. Here, we show deletion of NKX2-5, a critical component of the cardiac gene regulatory network, in human embryonic stem cells (hESCs), results in impaired cardiomyogenesis, failure to activate VCAM1 and to downregulate the progenitor marker PDGFRα. Furthermore, NKX2-5 null cardiomyocytes have abnormal physiology, with asynchronous contractions and altered action potentials. Molecular profiling and genetic rescue experiments demonstrate that the bHLH protein HEY2 is a key mediator of NKX2-5 function during human cardiomyogenesis. These findings identify HEY2 as a novel component of the NKX2-5 cardiac transcriptional network, providing tangible evidence that hESC models can decipher the complex pathways that regulate early stage human heart development. These data provide a human context for the evaluation of pathogenic mutations in congenital heart disease.
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Phylogenetic divergence of cell biological features
2018-01-01
Most cellular features have a range of states, but understanding the mechanisms responsible for interspecific divergence is a challenge for evolutionary cell biology. Models are developed for the distribution of mean phenotypes likely to evolve under the joint forces of mutation and genetic drift in the face of constant selection pressures. Mean phenotypes will deviate from optimal states to a degree depending on the effective population size, potentially leading to substantial divergence in the absence of diversifying selection. The steady-state distribution for the mean can even be bimodal, with one domain being largely driven by selection and the other by mutation pressure, leading to the illusion of phenotypic shifts being induced by movement among alternative adaptive domains. These results raise questions as to whether lineage-specific selective pressures are necessary to account for interspecific divergence, providing a possible platform for the establishment of null models for the evolution of cell-biological traits. PMID:29927740
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Flamenco, a gene controlling the gypsy retrovirus of drosophila melanogaster
DOE Office of Scientific and Technical Information (OSTI.GOV)
Prud`homme, N.; Gans, M.; Masson, M.
1995-02-01
Gypsy is an endogenous retrovirus of Drosophila melanogaster. It is table and does not transpose with detectable frequencies in most Drosophila strains. However, we have characterized unstable strains, known as MG, in which it transposes at high frequency. These stocks contain more copies of gypsy than usual stocks. Transposition results in mutations in several genes such as ovo and cut. They are stable and are due to gypsy insertions. Integrations into the ovo{sup D1} female sterile-dominant mutation result in a null allele of the gene and occurrence of fertile females. This phenomenon, known as the ovo{sup D1} reversion assay, canmore » be used to quantitate gypsy activity. We have shown that the properties of MG strains result from mutation of a host gene that we called flamenco (flam). It has a strict maternal effect on gypsy mobilization: transposition occurs at high frequency only in the germ line of the progeny of females homozygous for mutations of the gene. It is located at position 65.9 (20A1-3) on the X chromosome. The mutant allele present in MG strains is essentially recessive. Flamenco seems to control the infective properties of gypsy. 40 refs., 10 figs., 6 tabs.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Jiang, J.C.; Lee, W.R.; Chang, S.H.
1992-01-01
To study mechanisms for dominance of phenotype, eight ENU- and four x-ray-induced mutations at the alcohol dehydrogenase (Adh) locus were analyzed for partial dominance in their interaction with normal alleles. All ENU and one of the x-ray mutations were single base substitutions; the other three x-ray mutations were 9-21 base deletions. All but one of the 12 mutant alleles were selected for this study because they produced detectable mutant polypeptides, but seven of the 11 producing a peptide could not form dimers with the normal peptide and the enzyme activity of heterozygotes was about half that of normal homozygotes. Fourmore » mutations formed dimers with a decreased catalytic efficiency and two of these were near the limit of detectability; these two also inhibited the formation of normal homodimers. The mutant alleles therefore show multiple mechanisms leading to partial enzyme expression in heterozygotes and a wide range of dominance ranging from almost complete recessive to nearly dominant. All amino acid changes in mutant peptides that form dimers are located between amino acids 182 and 194, so this region is not critical for dimerization. It may, however, be an important surface domain for catalyzation. 34 refs., 8 figs., 2 tabs.« less