Genetic causes of male infertility.

PubMed

Stouffs, Katrien; Seneca, Sara; Lissens, Willy

2014-05-01

Male infertility, affecting around half of the couples with a problem to get pregnant, is a very heterogeneous condition. Part of patients are having a defect in spermatogenesis of which the underlying causes (including genetic ones) remain largely unknown. The only genetic tests routinely used in the diagnosis of male infertility are the analyses for the presence of Yq microdeletions and/or chromosomal abnormalities. Various other single gene or polygenic defects have been proposed to be involved in male fertility. Yet, their causative effect often remains to be proven. The recent evolution in the development of whole genome-based techniques may help in clarifying the role of genes and other genetic factors involved in spermatogenesis and spermatogenesis defects. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

The drosophila fragile X protein dFMR1 is required during early embryogenesis for pole cell formation and rapid nuclear division cycles.

PubMed

Deshpande, Girish; Calhoun, Gretchen; Schedl, Paul

2006-11-01

The FMR family of KH domain RNA-binding proteins is conserved from invertebrates to humans. In humans, inactivation of the X-linked FMR gene fragile X is the most common cause of mental retardation and leads to defects in neuronal architecture. While there are three FMR family members in humans, there is only a single gene, dfmr1, in flies. As in humans, inactivation of dfmr1 causes defects in neuronal architecture and in behavior. dfmr1 has other functions in the fly in addition to neurogenesis. Here we have analyzed its role during early embryonic development. We found that dfmr1 embryos display defects in the rapid nuclear division cycles that precede gastrulation in nuclear migration and in pole cell formation. While the aberrations in nuclear division are correlated with a defect in the assembly of centromeric/centric heterochromatin, the defects in pole cell formation are associated with alterations in the actin-myosin cytoskeleton.

Mutation update of transcription factor genes FOXE3, HSF4, MAF, and PITX3 causing cataracts and other developmental ocular defects.

PubMed

Anand, Deepti; Agrawal, Smriti A; Slavotinek, Anne; Lachke, Salil A

2018-04-01

Mutations in the transcription factor genes FOXE3, HSF4, MAF, and PITX3 cause congenital lens defects including cataracts that may be accompanied by defects in other components of the eye or in nonocular tissues. We comprehensively describe here all the variants in FOXE3, HSF4, MAF, and PITX3 genes linked to human developmental defects. A total of 52 variants for FOXE3, 18 variants for HSF4, 20 variants for MAF, and 19 variants for PITX3 identified so far in isolated cases or within families are documented. This effort reveals FOXE3, HSF4, MAF, and PITX3 to have 33, 16, 18, and 7 unique causal mutations, respectively. Loss-of-function mutant animals for these genes have served to model the pathobiology of the associated human defects, and we discuss the currently known molecular function of these genes, particularly with emphasis on their role in ocular development. Finally, we make the detailed FOXE3, HSF4, MAF, and PITX3 variant information available in the Leiden Online Variation Database (LOVD) platform at https://www.LOVD.nl/FOXE3, https://www.LOVD.nl/HSF4, https://www.LOVD.nl/MAF, and https://www.LOVD.nl/PITX3. Thus, this article informs on key variants in transcription factor genes linked to cataract, aphakia, corneal opacity, glaucoma, microcornea, microphthalmia, anterior segment mesenchymal dysgenesis, and Ayme-Gripp syndrome, and facilitates their access through Web-based databases. © 2018 Wiley Periodicals, Inc.

Genetics of intellectual disability in consanguineous families.

PubMed

Hu, Hao; Kahrizi, Kimia; Musante, Luciana; Fattahi, Zohreh; Herwig, Ralf; Hosseini, Masoumeh; Oppitz, Cornelia; Abedini, Seyedeh Sedigheh; Suckow, Vanessa; Larti, Farzaneh; Beheshtian, Maryam; Lipkowitz, Bettina; Akhtarkhavari, Tara; Mehvari, Sepideh; Otto, Sabine; Mohseni, Marzieh; Arzhangi, Sanaz; Jamali, Payman; Mojahedi, Faezeh; Taghdiri, Maryam; Papari, Elaheh; Soltani Banavandi, Mohammad Javad; Akbari, Saeide; Tonekaboni, Seyed Hassan; Dehghani, Hossein; Ebrahimpour, Mohammad Reza; Bader, Ingrid; Davarnia, Behzad; Cohen, Monika; Khodaei, Hossein; Albrecht, Beate; Azimi, Sarah; Zirn, Birgit; Bastami, Milad; Wieczorek, Dagmar; Bahrami, Gholamreza; Keleman, Krystyna; Vahid, Leila Nouri; Tzschach, Andreas; Gärtner, Jutta; Gillessen-Kaesbach, Gabriele; Varaghchi, Jamileh Rezazadeh; Timmermann, Bernd; Pourfatemi, Fatemeh; Jankhah, Aria; Chen, Wei; Nikuei, Pooneh; Kalscheuer, Vera M; Oladnabi, Morteza; Wienker, Thomas F; Ropers, Hans-Hilger; Najmabadi, Hossein

2018-01-04

Autosomal recessive (AR) gene defects are the leading genetic cause of intellectual disability (ID) in countries with frequent parental consanguinity, which account for about 1/7th of the world population. Yet, compared to autosomal dominant de novo mutations, which are the predominant cause of ID in Western countries, the identification of AR-ID genes has lagged behind. Here, we report on whole exome and whole genome sequencing in 404 consanguineous predominantly Iranian families with two or more affected offspring. In 219 of these, we found likely causative variants, involving 77 known and 77 novel AR-ID (candidate) genes, 21 X-linked genes, as well as 9 genes previously implicated in diseases other than ID. This study, the largest of its kind published to date, illustrates that high-throughput DNA sequencing in consanguineous families is a superior strategy for elucidating the thousands of hitherto unknown gene defects underlying AR-ID, and it sheds light on their prevalence.

Mutations in ZMYND10, a Gene Essential for Proper Axonemal Assembly of Inner and Outer Dynein Arms in Humans and Flies, Cause Primary Ciliary Dyskinesia

PubMed Central

Moore, Daniel J.; Onoufriadis, Alexandros; Shoemark, Amelia; Simpson, Michael A.; zur Lage, Petra I.; de Castro, Sandra C.; Bartoloni, Lucia; Gallone, Giuseppe; Petridi, Stavroula; Woollard, Wesley J.; Antony, Dinu; Schmidts, Miriam; Didonna, Teresa; Makrythanasis, Periklis; Bevillard, Jeremy; Mongan, Nigel P.; Djakow, Jana; Pals, Gerard; Lucas, Jane S.; Marthin, June K.; Nielsen, Kim G.; Santoni, Federico; Guipponi, Michel; Hogg, Claire; Antonarakis, Stylianos E.; Emes, Richard D.; Chung, Eddie M.K.; Greene, Nicholas D.E.; Blouin, Jean-Louis; Jarman, Andrew P.; Mitchison, Hannah M.

2013-01-01

Primary ciliary dyskinesia (PCD) is a ciliopathy characterized by airway disease, infertility, and laterality defects, often caused by dual loss of the inner dynein arms (IDAs) and outer dynein arms (ODAs), which power cilia and flagella beating. Using whole-exome and candidate-gene Sanger resequencing in PCD-affected families afflicted with combined IDA and ODA defects, we found that 6/38 (16%) carried biallelic mutations in the conserved zinc-finger gene BLU (ZMYND10). ZMYND10 mutations conferred dynein-arm loss seen at the ultrastructural and immunofluorescence level and complete cilia immotility, except in hypomorphic p.Val16Gly (c.47T>G) homozygote individuals, whose cilia retained a stiff and slowed beat. In mice, Zmynd10 mRNA is restricted to regions containing motile cilia. In a Drosophila model of PCD, Zmynd10 is exclusively expressed in cells with motile cilia: chordotonal sensory neurons and sperm. In these cells, P-element-mediated gene silencing caused IDA and ODA defects, proprioception deficits, and sterility due to immotile sperm. Drosophila Zmynd10 with an equivalent c.47T>G (p.Val16Gly) missense change rescued mutant male sterility less than the wild-type did. Tagged Drosophila ZMYND10 is localized primarily to the cytoplasm, and human ZMYND10 interacts with LRRC6, another cytoplasmically localized protein altered in PCD. Using a fly model of PCD, we conclude that ZMYND10 is a cytoplasmic protein required for IDA and ODA assembly and that its variants cause ciliary dysmotility and PCD with laterality defects. PMID:23891471

Mitochondrial myopathies.

PubMed

DiMauro, Salvatore

2006-11-01

Our understanding of mitochondrial diseases (defined restrictively as defects of the mitochondrial respiratory chain) is expanding rapidly. In this review, I will give the latest information on disorders affecting predominantly or exclusively skeletal muscle. The most recently described mitochondrial myopathies are due to defects in nuclear DNA, including coenzyme Q10 deficiency and mutations in genes controlling mitochondrial DNA abundance and structure, such as POLG, TK2, and MPV17. Barth syndrome, an X-linked recessive mitochondrial myopathy/cardiopathy, is associated with decreased amount and altered structure of cardiolipin, the main phospholipid of the inner mitochondrial membrane, but a secondary impairment of respiratory chain function is plausible. The role of mutations in protein-coding genes of mitochondrial DNA in causing isolated myopathies has been confirmed. Mutations in tRNA genes of mitochondrial DNA can also cause predominantly myopathic syndromes and--contrary to conventional wisdom--these mutations can be homoplasmic. Defects in the mitochondrial respiratory chain impair energy production and almost invariably involve skeletal muscle, causing exercise intolerance, cramps, recurrent myoglobinuria, or fixed weakness, which often affects extraocular muscles and results in droopy eyelids (ptosis) and progressive external ophthalmoplegia.

Disease severity in a mouse model of ataxia telangiectasia is modulated by the DNA damage checkpoint gene Hus1

PubMed Central

Balmus, Gabriel; Zhu, Min; Mukherjee, Sucheta; Lyndaker, Amy M.; Hume, Kelly R.; Lee, Jaesung; Riccio, Mark L.; Reeves, Anthony P.; Sutter, Nathan B.; Noden, Drew M.; Peters, Rachel M.; Weiss, Robert S.

2012-01-01

The human genomic instability syndrome ataxia telangiectasia (A-T), caused by mutations in the gene encoding the DNA damage checkpoint kinase ATM, is characterized by multisystem defects including neurodegeneration, immunodeficiency and increased cancer predisposition. ATM is central to a pathway that responds to double-strand DNA breaks, whereas the related kinase ATR leads a parallel signaling cascade that is activated by replication stress. To dissect the physiological relationship between the ATM and ATR pathways, we generated mice defective for both. Because complete ATR pathway inactivation causes embryonic lethality, we weakened the ATR mechanism to different degrees by impairing HUS1, a member of the 911 complex that is required for efficient ATR signaling. Notably, simultaneous ATM and HUS1 defects caused synthetic lethality. Atm/Hus1 double-mutant embryos showed widespread apoptosis and died mid-gestationally. Despite the underlying DNA damage checkpoint defects, increased DNA damage signaling was observed, as evidenced by H2AX phosphorylation and p53 accumulation. A less severe Hus1 defect together with Atm loss resulted in partial embryonic lethality, with the surviving double-mutant mice showing synergistic increases in genomic instability and specific developmental defects, including dwarfism, craniofacial abnormalities and brachymesophalangy, phenotypes that are observed in several human genomic instability disorders. In addition to identifying tissue-specific consequences of checkpoint dysfunction, these data highlight a robust, cooperative configuration for the mammalian DNA damage response network and further suggest HUS1 and related genes in the ATR pathway as candidate modifiers of disease severity in A-T patients. PMID:22575700

CFTR Modulators for the Treatment of Cystic Fibrosis.

PubMed

Pettit, Rebecca S; Fellner, Chris

2014-07-01

Defects in a single gene lead to the defective proteins that cause cystic fibrosis, making the disease an ideal candidate for mutation-targeted therapy. Although ivacaftor is currently the only FDA-approved CFTR modifier, others are in development.

Osteogenesis imperfecta due to mutations in non-collagenous genes: lessons in the biology of bone formation.

PubMed

Marini, Joan C; Reich, Adi; Smith, Simone M

2014-08-01

Osteogenesis imperfecta or 'brittle bone disease' has mainly been considered a bone disorder caused by collagen mutations. Within the last decade, however, a surge of genetic discoveries has created a new paradigm for osteogenesis imperfecta as a collagen-related disorder, where most cases are due to autosomal dominant type I collagen defects, while rare, mostly recessive, forms are due to defects in genes whose protein products interact with collagen protein. This review is both timely and relevant in outlining the genesis, development, and future of this paradigm shift in the understanding of osteogenesis imperfecta. Bone-restricted interferon-induced transmembrane (IFITM)-like protein (BRIL) and pigment epithelium-derived factor (PEDF) defects cause types V and VI osteogenesis imperfecta via defective bone mineralization, while defects in cartilage-associated protein (CRTAP), prolyl 3-hydroxylase 1 (P3H1), and cyclophilin B (CYPB) cause types VII-IX osteogenesis imperfecta via defective collagen post-translational modification. Heat shock protein 47 (HSP47) and FK506-binding protein-65 (FKBP65) defects cause types X and XI osteogenesis imperfecta via aberrant collagen crosslinking, folding, and chaperoning, while defects in SP7 transcription factor, wingless-type MMTV integration site family member 1 (WNT1), trimeric intracellular cation channel type b (TRIC-B), and old astrocyte specifically induced substance (OASIS) disrupt osteoblast development. Finally, absence of the type I collagen C-propeptidase bone morphogenetic protein 1 (BMP1) causes type XII osteogenesis imperfecta due to altered collagen maturation/processing. Identification of these multiple causative defects has provided crucial information for accurate genetic counseling, inspired a recently proposed functional grouping of osteogenesis imperfecta types by shared mechanism to simplify current nosology, and has prodded investigations into common pathways in osteogenesis imperfecta. Such investigations could yield critical information on cellular and bone tissue mechanisms and translate to new mechanistic insight into clinical therapies for patients.

Monoallelic mutation analysis (MAMA) for identifying germline mutations.

PubMed

Papadopoulos, N; Leach, F S; Kinzler, K W; Vogelstein, B

1995-09-01

Dissection of germline mutations in a sensitive and specific manner presents a continuing challenge. In dominantly inherited diseases, mutations occur in only one allele and are often masked by the normal allele. Here we report the development of a sensitive and specific diagnostic strategy based on somatic cell hybridization termed MAMA (monoallelic mutation analysis). We have demonstrated the utility of this strategy in two different hereditary colorectal cancer syndromes, one caused by a defective tumour suppressor gene on chromosome 5 (familial adenomatous polyposis, FAP) and the other caused by a defective mismatch repair gene on chromosome 2 (hereditary non-polyposis colorectal cancer, HNPCC).

Causes of Pediatric Cardiomyopathy

MedlinePlus

... pediatric cardiomyopathy. Mutations are defects in the DNA spiral, the protein structure of many genes. The abnormalities ... in the future there will be a clinical method to identify carriers of the gene within affected ...

Vacuolar invertase gene silencing in potato (Solanum tuberosum L.) improves processing quality by decreasing the frequency of sugar-end defects

USDA-ARS?s Scientific Manuscript database

Sugar-end defect is a tuber quality disorder that causes unacceptable darkening of one end of French fries. This defect appears when environmental stress during tuber growth increases post-harvest vacuolar acid invertase activity at one end of the tuber. Reducing sugars produced by invertase form da...

Molecular basis of abnormal red-green color vision: a family with three types of color vision defects.

PubMed Central

Drummond-Borg, M; Deeb, S; Motulsky, A G

1988-01-01

The molecular nature of three different types of X-linked color-vision defects, protanomaly, deuteranomaly, and protanopia, in a large 3-generation family was determined. In the protanomalous and protanopic males the normal red pigment gene was replaced by a 5' red-3' green fusion gene. The protanomalous male had more red pigment DNA in his fusion gene than did the more severely affected protanopic individual. The deuteranomalous individual had four green pigment genes and one 5' green-3' red fusion gene. These results extend those of Nathans et al., who proposed that most red-green color-vision defects arise as a result of unequal crossing-over between the red and green pigment genes. The various data suggest that differences in severity of color-vision defects associated with fusion genes are caused by differences in crossover sites between the red and green pigment genes. Currently used molecular methodology is not sufficiently sensitive to define these fusion points accurately, and the specific color-vision defect within the deutan or protan class cannot be predicted. The DNA patterns for color-vision genes of female heterozygotes have not previously been described. Patterns of heterozygotes may not be distinguishable from those of normals. However, a definite assignment of the various color pigment gene arrays could be carried out by family study. Two compound heterozygotes for color-vision defects who tested as normal by anomaloscopy were found to carry abnormal fusion genes. In addition, a normal red pigment gene was present on one chromosome and at least one normal green pigment gene was present on the other.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 3 PMID:2847528

Inherited Mitochondrial Diseases of DNA Replication

PubMed Central

Copeland, William C.

2007-01-01

Mitochondrial genetic diseases can result from defects in mitochondrial DNA (mtDNA) in the form of deletions, point mutations, or depletion, which ultimately cause loss of oxidative phosphorylation. These mutations may be spontaneous, maternally inherited, or a result of inherited nuclear defects in genes that maintain mtDNA. This review focuses on our current understanding of nuclear gene mutations that produce mtDNA alterations and cause mitochondrial depletion syndrome (MDS), progressive external ophthalmoplegia (PEO), ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). To date, all of these etiologic nuclear genes fall into one of two categories: genes whose products function directly at the mtDNA replication fork, such as POLG, POLG2, and TWINKLE, or genes whose products supply the mitochondria with deoxynucleotide triphosphate pools needed for DNA replication, such as TK2, DGUOK, TP, SUCLA2, ANT1, and possibly the newly identified MPV17. PMID:17892433

Congenital Defects.

ERIC Educational Resources Information Center

Goldman, Allen S.; And Others

There are two general categories (not necessarily mutually exclusive) of congenital defects: (1) abnormalities that have an hereditary basis, such as single and multiple genes, or chromosomal abberration; and (2) abnormalities that are caused by nonhereditary factors, such as malnutrition, maternal disease, radiation, infections, drugs, or…

Plastid signalling under multiple conditions is accompanied by a common defect in RNA editing in plastids.

PubMed

Kakizaki, Tomohiro; Yazu, Fumiko; Nakayama, Katsuhiro; Ito-Inaba, Yasuko; Inaba, Takehito

2012-01-01

Retrograde signalling from the plastid to the nucleus, also known as plastid signalling, plays a key role in coordinating nuclear gene expression with the functional state of plastids. Inhibitors that cause plastid dysfunction have been suggested to generate specific plastid signals related to their modes of action. However, the molecules involved in plastid signalling remain to be identified. Genetic studies indicate that the plastid-localized pentatricopeptide repeat protein GUN1 mediates signalling under several plastid signalling-related conditions. To elucidate further the nature of plastid signals, investigations were carried out to determine whether different plastid signal-inducing treatments had similar effects on plastids and on nuclear gene expression. It is demonstrated that norflurazon and lincomycin treatments and the plastid protein import2-2 (ppi2-2) mutation, which causes a defect in plastid protein import, all resulted in similar changes at the gene expression level. Furthermore, it was observed that these three treatments resulted in defective RNA editing in plastids. This defect in RNA editing was not a secondary effect of down-regulation of pentatricopeptide repeat protein gene expression in the nucleus. The results indicate that these three treatments, which are known to induce plastid signals, affect RNA editing in plastids, suggesting an unprecedented link between plastid signalling and RNA editing.

Superoxide Dismutase 1 In Vivo Ameliorates Maternal Diabetes Mellitus-Induced Apoptosis and Heart Defects Through Restoration of Impaired Wnt Signaling.

PubMed

Wang, Fang; Fisher, Steven A; Zhong, Jianxiang; Wu, Yanqing; Yang, Peixin

2015-10-01

Oxidative stress is manifested in embryos exposed to maternal diabetes mellitus, yet specific mechanisms for diabetes mellitus-induced heart defects are not defined. Gene deletion of intermediates of Wingless-related integration (Wnt) signaling causes heart defects similar to those observed in embryos from diabetic pregnancies. We tested the hypothesis that diabetes mellitus-induced oxidative stress impairs Wnt signaling, thereby causing heart defects, and that these defects can be rescued by transgenic overexpression of the reactive oxygen species scavenger superoxide dismutase 1 (SOD1). Wild-type (WT) and SOD1-overexpressing embryos from nondiabetic WT control dams and nondiabetic/diabetic WT female mice mated with SOD1 transgenic male mice were analyzed. No heart defects were observed in WT and SOD1 embryos under nondiabetic conditions. WT embryos of diabetic dams had a 26% incidence of cardiac outlet defects that were suppressed by SOD1 overexpression. Insulin treatment reduced blood glucose levels and heart defects. Diabetes mellitus increased superoxide production, canonical Wnt antagonist expression, caspase activation, and apoptosis and suppressed cell proliferation. Diabetes mellitus suppressed Wnt signaling intermediates and Wnt target gene expression in the embryonic heart, each of which were reversed by SOD1 overexpression. Hydrogen peroxide and peroxynitrite mimicked the inhibitory effect of high glucose on Wnt signaling, which was abolished by the SOD1 mimetic, tempol. The oxidative stress of diabetes mellitus impairs Wnt signaling and causes cardiac outlet defects that are rescued by SOD1 overexpression. This suggests that targeting of components of the Wnt5a signaling pathway may be a viable strategy for suppression of congenital heart defects in fetuses of diabetic pregnancies. © 2015 American Heart Association, Inc.

Advances in clinical immunology in 2015.

PubMed

Chinen, Javier; Notarangelo, Luigi D; Shearer, William T

2016-12-01

Advances in clinical immunology in the past year included the report of practice parameters for the diagnosis and management of primary immunodeficiencies to guide the clinician in the approach to these relatively uncommon disorders. We have learned of new gene defects causing immunodeficiency and of new phenotypes expanding the spectrum of conditions caused by genetic mutations such as a specific regulator of telomere elongation (RTEL1) mutation causing isolated natural killer cell deficiency and mutations in ras-associated RAB (RAB27) resulting in immunodeficiency without albinism. Advances in diagnosis included the increasing use of whole-exome sequencing to identify gene defects and the measurement of serum free light chains to identify secondary hypogammaglobulinemias. For several primary immunodeficiencies, improved outcomes have been reported after definitive therapy with hematopoietic stem cell transplantation and gene therapy. Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Impaired Mitochondrial Dynamics Underlie Axonal Defects in Hereditary Spastic Paraplegias.

PubMed

Denton, Kyle; Mou, Yongchao; Xu, Chong-Chong; Shah, Dhruvi; Chang, Jaerak; Blackstone, Craig; Li, Xue-Jun

2018-05-02

Mechanisms by which long corticospinal axons degenerate in hereditary spastic paraplegia (HSP) are largely unknown. Here, we have generated induced pluripotent stem cells (iPSCs) from patients with two autosomal recessive forms of HSP, SPG15 and SPG48, which are caused by mutations in the ZFYVE26 and AP5Z1 genes encoding proteins in the same complex, the spastizin and AP5Z1 proteins, respectively. In patient iPSC-derived telencephalic glutamatergic and midbrain dopaminergic neurons, neurite number, length and branching are significantly reduced, recapitulating disease-specific phenotypes. We analyzed mitochondrial morphology and noted a significant reduction in both mitochondrial length and their densities within axons of these HSP neurons. Mitochondrial membrane potential was also decreased, confirming functional mitochondrial defects. Notably, mdivi-1, an inhibitor of the mitochondrial fission GTPase DRP1, rescues mitochondrial morphology defects and suppresses the impairment in neurite outgrowth and late-onset apoptosis in HSP neurons. Furthermore, knockdown of these HSP genes causes similar axonal defects, also mitigated by treatment with mdivi-1. Finally, neurite outgrowth defects in SPG15 and SPG48 cortical neurons can be rescued by knocking down DRP1 directly. Thus, abnormal mitochondrial morphology caused by an imbalance of mitochondrial fission and fusion underlies specific axonal defects and serves as a potential therapeutic target for SPG15 and SPG48.

Haploinsufficiency of TAB2 Causes Congenital Heart Defects in Humans

PubMed Central

Thienpont, Bernard; Zhang, Litu; Postma, Alex V.; Breckpot, Jeroen; Tranchevent, Léon-Charles; Van Loo, Peter; Møllgård, Kjeld; Tommerup, Niels; Bache, Iben; Tümer, Zeynep; van Engelen, Klaartje; Menten, Björn; Mortier, Geert; Waggoner, Darrel; Gewillig, Marc; Moreau, Yves; Devriendt, Koen; Larsen, Lars Allan

2010-01-01

Congenital heart defects (CHDs) are the most common major developmental anomalies and the most frequent cause for perinatal mortality, but their etiology remains often obscure. We identified a locus for CHDs on 6q24-q25. Genotype-phenotype correlations in 12 patients carrying a chromosomal deletion on 6q delineated a critical 850 kb region on 6q25.1 harboring five genes. Bioinformatics prioritization of candidate genes in this locus for a role in CHDs identified the TGF-β-activated kinase 1/MAP3K7 binding protein 2 gene (TAB2) as the top-ranking candidate gene. A role for this candidate gene in cardiac development was further supported by its conserved expression in the developing human and zebrafish heart. Moreover, a critical, dosage-sensitive role during development was demonstrated by the cardiac defects observed upon titrated knockdown of tab2 expression in zebrafish embryos. To definitively confirm the role of this candidate gene in CHDs, we performed mutation analysis of TAB2 in 402 patients with a CHD, which revealed two evolutionarily conserved missense mutations. Finally, a balanced translocation was identified, cosegregating with familial CHD. Mapping of the breakpoints demonstrated that this translocation disrupts TAB2. Taken together, these data clearly demonstrate a role for TAB2 in human cardiac development. PMID:20493459

A syndrome of multiorgan hyperplasia with features of gigantism, tumorigenesis, and female sterility in p27(Kip1)-deficient mice.

PubMed

Fero, M L; Rivkin, M; Tasch, M; Porter, P; Carow, C E; Firpo, E; Polyak, K; Tsai, L H; Broudy, V; Perlmutter, R M; Kaushansky, K; Roberts, J M

1996-05-31

Targeted disruption of the murine p27(Kip1) gene caused a gene dose-dependent increase in animal size without other gross morphologic abnormalities. All tissues were enlarged and contained more cells, although endocrine abnormalities were not evident. Thymic hyperplasia was associated with increased T lymphocyte proliferation, and T cells showed enhanced IL-2 responsiveness in vitro. Thus, p27 deficiency may cause a cell-autonomous defect resulting in enhanced proliferation in response to mitogens. In the spleen, the absence of p27 selectively enhanced proliferation of hematopoietic progenitor cells. p27 deletion, like deletion of the Rb gene, uniquely caused neoplastic growth of the pituitary pars intermedia, suggesting that p27 and Rb function in the same regulatory pathway. The absence of p27 also caused an ovulatory defect and female sterility. Maturation of secondary ovarian follicles into corpora lutea, which express high levels of p27, was markedly impaired.

Lipid signalling couples translational surveillance to systemic detoxification in Caenorhabditis elegans

PubMed Central

Govindan, J. Amaranath; Jayamani, Elamparithi; Zhang, Xinrui; Breen, Peter; Larkins-Ford, Jonah; Mylonakis, Eleftherios

2015-01-01

Translation in eukaryotes is surveilled to detect toxins and virulence factors and coupled to the induction of defense pathways. C. elegans germline-specific mutations in translation components are detected by this system to induce detoxification and immune responses in distinct somatic cells. An RNAi screen revealed gene inactivations that act at multiple steps in lipid biosynthetic and kinase pathways that act upstream of MAP kinase to mediate the systemic communication of translation-defects to induce detoxification genes. Mammalian bile acids can rescue the defect in detoxification gene induction caused by C. elegans lipid biosynthetic gene inactivations. Extracts prepared from C. elegans with translation deficits but not from wild type can also rescue detoxification gene induction in lipid biosynthetic defective strains. These eukaryotic antibacterial countermeasures are not ignored by bacteria: particular bacterial species suppress normal C. elegans detoxification responses to mutations in translation factors. PMID:26322678

The Child with Recurrent Mycobacterial Disease.

PubMed

Reed, Brian; Dolen, William K

2018-06-23

Many genetic conditions predispose affected individuals to opportunistic infections. A number of immunodeficiency diseases, including genetic defects termed Mendelian susceptibility to mycobacterial disease (MSMD), permit infection from many different strains of mycobacteria that would otherwise not cause disease. These include tuberculous and nontuberculous mycobacteria, and bacille Calmette-Guérin vaccine (BCG). Patients may present with infections from other organisms that depend on macrophage function for containment. Defects in multiple genes in the IL-12 and NFKB signaling pathways can cause the MSMD phenotype, some of which include IL12RB1, IL12B, IKBKG, ISG15, IFNGR1, IFNGR2, CYBB, TYK2, IRF8, and STAT1. Multiple autosomal recessive and dominant, and 2 X-linked recessive gene defects resulting in the MSMD phenotype have been reported, and others await discovery. This review presents the known gene defects and describes clinical findings that result from the mutations. If MSMD is suspected, a careful clinical history and examination and basic immunodeficiency screening tests will narrow the differential diagnosis. A specific diagnosis requires more sophisticated laboratory investigation. Genetic testing permits a definitive diagnosis, permitting genetic counseling. Mild cases respond well to appropriate antibiotic therapy, whereas severe disease may require hematopoietic stem cell transplantation.

The expanding phenotype of mitochondrial myopathy.

PubMed

DiMauro, Salvatore; Gurgel-Giannetti, Juliana

2005-10-01

Our understanding of mitochondrial diseases (defined restrictively as defects in the mitochondrial respiratory chain) continues to progress apace. In this review we provide an update of information regarding disorders that predominantly or exclusively affect skeletal muscle. Most recently described mitochondrial myopathies are due to defects in nuclear DNA, including coenzyme Q10 deficiency, and mutations in genes that control mitochondrial DNA (mtDNA) abundance and structure such as POLG and TK2. Barth syndrome, an X-linked recessive mitochondrial myopathy/cardiopathy, is associated with altered lipid composition of the inner mitochondrial membrane, but a putative secondary impairment of the respiratory chain remains to be documented. Concerning the 'other genome', the role played by mutations in protein encoding genes of mtDNA in causing isolated myopathies has been confirmed. It has also been confirmed that mutations in tRNA genes of mtDNA can cause predominantly myopathic syndromes and - contrary to conventional wisdom - these mutations can be homoplasmic. Defects in the mitochondrial respiratory chain impair energy production and almost invariably involve skeletal muscle, causing exercise intolerance, myalgia, cramps, or fixed weakness, which often affects extraocular muscles and results in droopy eyelids (ptosis) and progressive external ophthalmoplegia.

A defect in the thymidine kinase 2 gene causing isolated mitochondrial myopathy without mtDNA depletion.

PubMed

Leshinsky-Silver, E; Michelson, M; Cohen, S; Ginsberg, M; Sadeh, M; Barash, V; Lerman-Sagie, T; Lev, D

2008-07-01

Isolated mitochondrial myopathies (IMM) are either due to primary defects in mtDNA, in nuclear genes that control mtDNA abundance and structure such as thymidine kinase 2 (TK2), or due to CoQ deficiency. Defects in the TK2 gene have been found to be associated with mtDNA depletion attributed to a depleted mitochondrial dNTP pool in non-dividing cells. We report an unusual case of IMM, homozygous for the H90N mutation in the TK2 gene but unlike other cases with the same mutation, does not demonstrate mtDNA depletion. The patient's clinical course is relatively mild and a muscle biopsy showed ragged red muscle fibers with a mild decrease in complexes I and an increase in complexes IV and II activities. This report extends the phenotypic expression of TK2 defects and suggests that all patients who present with an IMM even with normal quantities of mtDNA should be screened for TK2 mutations.

BCOR analysis in patients with OFCD and Lenz microphthalmia syndromes, mental retardation with ocular anomalies, and cardiac laterality defects

PubMed Central

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

An innovative strategy to clone positive modifier genes of defects caused by mtDNA mutations: MRPS18C as suppressor gene of m.3946G>A mutation in MT-ND1 gene.

PubMed

Rodríguez-García, María Elena; Cotrina-Vinagre, Francisco Javier; Carnicero-Rodríguez, Patricia; Martínez-Azorín, Francisco

2017-07-01

We have developed a new functional complementation approach to clone modifier genes which overexpression is able to suppress the biochemical defects caused by mtDNA mutations (suppressor genes). This strategy consists in transferring human genes into respiratory chain-deficient fibroblasts, followed by a metabolic selection in a highly selective medium. We used a normalized expression cDNA library in an episomal vector (pREP4) to transfect the fibroblasts, and a medium with glutamine and devoid of any carbohydrate source to select metabolically. Growing the patient's fibroblasts in this selective medium, the deficient cells rapidly disappear unless they are rescued by the cDNA of a suppressor gene. The use of an episomal vector allows us to carry out several rounds of transfection/selection (cyclical phenotypic rescue) to enrich the rescue with true clones of suppressor genes. Using fibroblasts from a patient with epileptic encephalopathy with the m.3946G>A (p.E214K) mutation in the MT-ND1 gene, several candidate genes were identified and one of them was characterized functionally. Thus, overexpression of MRPS18C gene (that encode for bS18m protein) suppressed the molecular defects produced by this mtDNA mutation, recovering the complex I activity and reducing the ROS produced by this complex to normal levels. We suggest that modulation of bS18m expression may be an effective therapeutic strategy for the patients with this mutation.

Growth hormone receptor gene mutations in two Italian patients with Laron Syndrome.

PubMed

Fassone, L; Corneli, G; Bellone, S; Camacho-Hübner, C; Aimaretti, G; Cappa, M; Ubertini, G; Bona, G

2007-05-01

Laron Syndrome (LS) represents a condition characterized by GH insensitivity caused by molecular defects in the GH receptor (GHR) gene or in the post-receptor signalling pathway. We report the molecular characterization of two unrelated Italian girls from Sicily diagnosed with LS. The DNA sequencing of the GHR gene revealed the presence of different nonsense mutations, occurring in the same background haplotype. The molecular defects occurred in the extracellular domain of the GHR leading to a premature termination signal and to a truncated non-functional receptor. In one patient, a homozygous G to T transversion, in exon 6, led to the mutation GAA to TAA at codon 180 (E180X), while in the second patient a homozygous C to T transition in exon 7 was detected, causing the CGA to TAA substitution at codon 217 (R217X). Both probands presented the polymorphisms Gly168Gly and Ile544Leu in a homozygous state in exons 6 and 10, respectively. The E180X represents a novel defect of the GHR gene, while the R217X mutation has been previously reported in several patients from different ethnic backgrounds but all from countries located in the Mediterranean and Middle Eastern region.

The Zn finger protein Iguana impacts Hedgehog signaling by promoting ciliogenesis.

PubMed

Glazer, Andrew M; Wilkinson, Alex W; Backer, Chelsea B; Lapan, Sylvain W; Gutzman, Jennifer H; Cheeseman, Iain M; Reddien, Peter W

2010-01-01

Hedgehog signaling is critical for metazoan development and requires cilia for pathway activity. The gene iguana was discovered in zebrafish as required for Hedgehog signaling, and encodes a novel Zn finger protein. Planarians are flatworms with robust regenerative capacities and utilize epidermal cilia for locomotion. RNA interference of Smed-iguana in the planarian Schmidtea mediterranea caused cilia loss and failure to regenerate new cilia, but did not cause defects similar to those observed in hedgehog(RNAi) animals. Smed-iguana gene expression was also similar in pattern to the expression of multiple other ciliogenesis genes, but was not required for expression of these ciliogenesis genes. iguana-defective zebrafish had too few motile cilia in pronephric ducts and in Kupffer's vesicle. Kupffer's vesicle promotes left-right asymmetry and iguana mutant embryos had left-right asymmetry defects. Finally, human Iguana proteins (dZIP1 and dZIP1L) localize to the basal bodies of primary cilia and, together, are required for primary cilia formation. Our results indicate that a critical and broadly conserved function for Iguana is in ciliogenesis and that this function has come to be required for Hedgehog signaling in vertebrates.

Single-cycle adenovirus vectors in the current vaccine landscape.

PubMed

Barry, Michael

2018-02-01

Traditional inactivated and protein vaccines generate strong antibodies, but struggle to generate T cell responses. Attenuated pathogen vaccines generate both, but risk causing the disease they aim to prevent. Newer gene-based vaccines drive both responses and avoid the risk of infection. While these replication-defective (RD) vaccines work well in small animals, they can be weak in humans because they do not replicate antigen genes like more potent replication-competent (RC) vaccines. RC vaccines generate substantially stronger immune responses, but also risk causing their own infections. To circumvent these problems, we developed single-cycle adenovirus (SC-Ad) vectors that amplify vaccine genes, but that avoid the risk of infection. This review will discuss these vectors and their prospects for use as vaccines. Areas covered: This review provides a background of different types of vaccines. The benefits of gene-based vaccines and their ability to replicate antigen genes are described. Adenovirus vectors are discussed and compared to other vaccine types. Replication-defective, single-cycle, and replication-competent Ad vaccines are compared. Expert commentary: The potential utility of these vaccines are discussed when used against infectious diseases and as cancer vaccines. We propose a move away from replication-defective vaccines towards more robust replication-competent or single-cycle vaccines.

Cardiac troponin T is necessary for normal development in the embryonic chick heart.

PubMed

England, Jennifer; Pang, Kar Lai; Parnall, Matthew; Haig, Maria Isabel; Loughna, Siobhan

2016-09-01

The heart is the first functioning organ to develop during embryogenesis. The formation of the heart is a tightly regulated and complex process, and alterations to its development can result in congenital heart defects. Mutations in sarcomeric proteins, such as alpha myosin heavy chain and cardiac alpha actin, have now been associated with congenital heart defects in humans, often with atrial septal defects. However, cardiac troponin T (cTNT encoded by gene TNNT2) has not. Using gene-specific antisense oligonucleotides, we have investigated the role of cTNT in chick cardiogenesis. TNNT2 is expressed throughout heart development and in the postnatal heart. TNNT2-morpholino treatment resulted in abnormal atrial septal growth and a reduction in the number of trabeculae in the developing primitive ventricular chamber. External analysis revealed the development of diverticula from the ventricular myocardial wall which showed no evidence of fibrosis and still retained a myocardial phenotype. Sarcomeric assembly appeared normal in these treated hearts. In humans, congenital ventricular diverticulum is a rare condition, which has not yet been genetically associated. However, abnormal haemodynamics is known to cause structural defects in the heart. Further, structural defects, including atrial septal defects and congenital diverticula, have previously been associated with conduction anomalies. Therefore, to provide mechanistic insights into the effect that cTNT knockdown has on the developing heart, quantitative PCR was performed to determine the expression of the shear stress responsive gene NOS3 and the conduction gene TBX3. Both genes were differentially expressed compared to controls. Therefore, a reduction in cTNT in the developing heart results in abnormal atrial septal formation and aberrant ventricular morphogenesis. We hypothesize that alterations to the haemodynamics, indicated by differential NOS3 expression, causes these abnormalities in growth in cTNT knockdown hearts. In addition, the muscular diverticula reported here suggest a novel role for mutations of structural sarcomeric proteins in the pathogenesis of congenital cardiac diverticula. From these studies, we suggest TNNT2 is a gene worthy of screening for those with a congenital heart defect, particularly atrial septal defects and ventricular diverticula. © 2016 The Authors. Journal of Anatomy published by John Wiley & Sons Ltd on behalf of Anatomical Society.

Evidence found for a possible [open quote]aggression gene[close quote

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morell, V.

1993-06-18

Researchers in the Netherlands are on the track of a genetic mutation in a large Dutch family that may cause periodic outbursts of aggression in its possessors. Han G. Brunner and his colleagues at Univ. Hospital in Nijmegen report evidence suggesting that a mutation in the gene for monoamine oxidase A (MAOA) may underlie the aggressive and sometimes violent behavior displayed by certain males in this family. A linkage between MAOA gene defect and behavioral problems would make biological sense because the enzyme encoded by the gene helps break down several neurotransmitters that might, if their concentrations build up abnormally,more » cause a person to respond excessively-and at times even violently-to stress. If this original report is borne out by further work, it would be the first time that a specific gene defect has been found to predispose its bearers to aggressive behavior. Using markers for the X chromosome, Brunner and his colleagues identified the MAO gene region as the likely site for the diseased gene.« less

Quebec platelet disorder.

PubMed

Hayward, Catherine P M; Rivard, Georges E

2011-04-01

Quebec platelet disorder (QPD) is an autosomal dominant bleeding disorder associated with a unique gain-of-function defect in fibrinolysis. In the past 5 years, there have been important advances in the understanding of the pathogenesis of QPD, including its genetic cause, which is a copy number variation mutation of PLAU, the gene for urokinase plasminogen activator (uPA). QPD is the first bleeding disorder identified to be caused by a PLAU mutation and it is also the first bleeding disorder recognized to result from a gene copy number mutation. The molecular defect of QPD leads to marked overexpression of uPA during megakaryopoiesis, producing profibrinolytic platelets that contain active forms of uPA in their α-granules. This article summarizes expert opinions on the features of QPD and recent advances in the understanding of its pathogenesis and genetic cause.

Tolerance of a Phage Element by Streptococcus pneumoniae Leads to a Fitness Defect during Colonization

PubMed Central

DeBardeleben, Hilary K.; Lysenko, Elena S.; Dalia, Ankur B.

2014-01-01

The pathogenesis of the disease caused by Streptococcus pneumoniae begins with colonization of the upper respiratory tract. Temperate phages have been identified in the genomes of up to 70% of clinical isolates. How these phages affect the bacterial host during colonization is unknown. Here, we examined a clinical isolate that carries a novel prophage element, designated Spn1, which was detected in both integrated and episomal forms. Surprisingly, both lytic and lysogenic Spn1 genes were expressed under routine growth conditions. Using a mouse model of asymptomatic colonization, we demonstrate that the Spn1− strain outcompeted the Spn1+ strain >70-fold. To determine if Spn1 causes a fitness defect through a trans-acting factor, we constructed an Spn1+ mutant that does not become an episome or express phage genes. This mutant competed equally with the Spn1− strain, indicating that expression of phage genes or phage lytic activity is required to confer this fitness defect. In vitro, we demonstrate that the presence of Spn1 correlated with a defect in LytA-mediated autolysis. Furthermore, the Spn1+ strain displayed increased chain length and resistance to lysis by penicillin compared to the Spn− strain, indicating that Spn1 alters the cell wall physiology of its host strain. We posit that these changes in cell wall physiology allow for tolerance of phage gene products and are responsible for the relative defect of the Spn1+ strain during colonization. This study provides new insight into how bacteria and prophages interact and affect bacterial fitness in vivo. PMID:24816604

Genetic screening of non-classic CAH females with hyperandrogenemia identifies a novel CYP11B1 gene mutation.

PubMed

Shammas, Christos; Byrou, Stefania; Phelan, Marie M; Toumba, Meropi; Stylianou, Charilaos; Skordis, Nicos; Neocleous, Vassos; Phylactou, Leonidas A

2016-04-01

Congenital adrenal hyperplasia (CAH) is an endocrine autosomal recessive disorder with various symptoms of diverse severity. Mild hyperandrogenemia is the most commonclinical feature in non-classic CAH patients and 95% of the cases are identified by mutations in the CYP21A2 gene. In the present study, the second most common cause for non-classic CAH (NC-CAH), 11β-hydroxylase deficiency due to mutations in the CYP11B1 gene, is investigated. Screening of the CYP21A2 and CYP11B1 genes by direct sequencing was carried out for the detection of possible genetic defects in patients with suspected CAH. It wasobserved that CYP11B1 variants co-exist only in rare cases along with mutations in CYP21A2 in patients clinically diagnosed with CAH. A total of 23 NC-CAH female patients out of 75 were identified with only one mutation in the CYP21A2 gene. The novel CYP11B1 gene mutation, p.Val484Asp, was identified in a patient with CAH in the heterozygous state. The structural characterization of the novel p.Val484Asp was found to likely cause distortion of the surrounding beta sheet and indirect destabilization of the cavity that occurs on the opposite face of the structural elements, leading to partial impairment of the enzymatic activity. CYP21A2 gene mutations are the most frequent genetic defects in cases of NC-CAH even when these patients are in the heterozygous state. These mutations have a diverse phenotype giving rise to a variable extent of cortisol synthesis impairment; it is also clear that CYP11B1 mutants are a rare type of defects causing CAH.

When intracellular logistics fails--genetic defects in membrane trafficking.

PubMed

Olkkonen, Vesa M; Ikonen, Elina

2006-12-15

The number of human genetic disorders shown to be due to defects in membrane trafficking has greatly increased during the past five years. Defects have been identified in components involved in sorting of cargo into transport carriers, vesicle budding and scission, movement of vesicles along cytoskeletal tracks, as well as in vesicle tethering, docking and fusion at the target membrane. The nervous system is extremely sensitive to such disturbances of the membrane trafficking machinery, and the majority of these disorders display neurological defects--particularly diseases affecting the motility of transport carriers along cytoskeletal tracks. In several disorders, defects in a component that represents a fundamental part of the trafficking machinery fail to cause global transport defects but result in symptoms limited to specific cell types and transport events; this apparently reflects the redundancy of the transport apparatus. In groups of closely related diseases such as Hermansky-Pudlak and Griscelli syndromes, identification of the underlying gene defects has revealed groups of genes in which mutations lead to similar phenotypic consequences. New functionally linked trafficking components and regulatory mechanisms have thus been discovered. Studies of the gene defects in trafficking disorders therefore not only open avenues for new therapeutic approaches but also significantly contribute to our knowledge of the fundamental mechanisms of intracellular membrane transport.

Kidney adysplasia and variable hydronephrosis, a new mutation affecting the odd-skipped related 1 gene in the mouse, causes variable defects in kidney development and hydronephrosis

PubMed Central

Davisson, Muriel T.; Cook, Susan A.; Akeson, Ellen C.; Liu, Don; Heffner, Caleb; Gudis, Polyxeni; Fairfield, Heather

2015-01-01

Many genes, including odd-skipped related 1 (Osr1), are involved in regulation of mammalian kidney development. We describe here a new recessive mutation (kidney adysplasia and variable hydronephrosis, kavh) in the mouse that leads to downregulation of Osr1 transcript, causing several kidney defects: agenesis, hypoplasia, and hydronephrosis with variable age of onset. The mutation is closely associated with a reciprocal translocation, T(12;17)4Rk, whose Chromosome 12 breakpoint is upstream from Osr1. The kavh/kavh mutant provides a model to study kidney development and test therapies for hydronephrosis. PMID:25834070

Kidney adysplasia and variable hydronephrosis, a new mutation affecting the odd-skipped related 1 gene in the mouse, causes variable defects in kidney development and hydronephrosis.

PubMed

Davisson, Muriel T; Cook, Susan A; Akeson, Ellen C; Liu, Don; Heffner, Caleb; Gudis, Polyxeni; Fairfield, Heather; Murray, Stephen A

2015-06-15

Many genes, including odd-skipped related 1 (Osr1), are involved in regulation of mammalian kidney development. We describe here a new recessive mutation (kidney adysplasia and variable hydronephrosis, kavh) in the mouse that leads to downregulation of Osr1 transcript, causing several kidney defects: agenesis, hypoplasia, and hydronephrosis with variable age of onset. The mutation is closely associated with a reciprocal translocation, T(12;17)4Rk, whose Chromosome 12 breakpoint is upstream from Osr1. The kavh/kavh mutant provides a model to study kidney development and test therapies for hydronephrosis. Copyright © 2015 the American Physiological Society.

Incomplete synthesis of N-glycans in congenital dyserythropoietic anemia type II caused by a defect in the gene encoding. alpha. -mannosidase II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fukuda, M.N.; Masri, K.A.; Dell, A.

1990-10-01

Congenital dyserythropoietic anemia type II, or hereditary erythroblastic multinuclearity with a positive acidified-serum-lysis test (HEMPAS), is a genetic anemia in humans inherited by an autosomally recessive mode. The enzyme defect in most HEMPAS patients has previously been proposed as a lowered activity of N-acetylglucosaminyltransferase II, resulting in a lack of polylactosamine on proteins and leading to the accumulation of polylactosaminyl lipids. A recent HEMPAS case, G.C., has now been analyzed by cell-surface labeling, fast-atom-bombardment mass spectrometry of glycopeptides, and activity assay of glycosylation enzymes. Significantly decreased glycosylation of polylactosaminoglycan proteins and incompletely processed asparagine-linked oligosaccharides were detected in the erythrocytemore » membranes of G.C. These results suggest that G.C. cells contain a mutation in {alpha}-ManII-encoding gene that results in inefficient expression of {alpha}-ManII mRNA, either through reduced transcription or message instability. This report demonstrates that HEMPAS is caused by a defective gene encoding an enzyme necessary for the synthesis of asparagine-linked oligosaccharides.« less

Defective pigment granule biogenesis and aberrant behavior caused by mutations in the Drosophila AP-3beta adaptin gene ruby.

PubMed Central

Kretzschmar, D; Poeck, B; Roth, H; Ernst, R; Keller, A; Porsch, M; Strauss, R; Pflugfelder, G O

2000-01-01

Lysosomal protein trafficking is a fundamental process conserved from yeast to humans. This conservation extends to lysosome-like organelles such as mammalian melanosomes and insect eye pigment granules. Recently, eye and coat color mutations in mouse (mocha and pearl) and Drosophila (garnet and carmine) were shown to affect subunits of the heterotetrameric adaptor protein complex AP-3 involved in vesicle trafficking. Here we demonstrate that the Drosophila eye color mutant ruby is defective in the AP-3beta subunit gene. ruby expression was found in retinal pigment and photoreceptor cells and in the developing central nervous system. ruby mutations lead to a decreased number and altered size of pigment granules in various cell types in and adjacent to the retina. Humans with lesions in the related AP-3betaA gene suffer from Hermansky-Pudlak syndrome, which is caused by defects in a number of lysosome-related organelles. Hermansky-Pudlak patients have a reduced skin pigmentation and suffer from internal bleeding, pulmonary fibrosis, and visual system malfunction. The Drosophila AP-3beta adaptin also appears to be involved in processes other than eye pigment granule biogenesis because all ruby allele combinations tested exhibited defective behavior in a visual fixation paradigm. PMID:10790396

Defective mitochondrial rRNA methyltransferase MRM2 causes MELAS-like clinical syndrome

PubMed Central

Garone, Caterina; D’Souza, Aaron R; Dallabona, Cristina; Lodi, Tiziana; Rebelo-Guiomar, Pedro; Rorbach, Joanna; Donati, Maria Alice; Procopio, Elena; Montomoli, Martino; Guerrini, Renzo; Zeviani, Massimo; Calvo, Sarah E; Mootha, Vamsi K; DiMauro, Salvatore; Ferrero, Ileana; Minczuk, Michal

2017-01-01

Abstract Defects in nuclear-encoded proteins of the mitochondrial translation machinery cause early-onset and tissue-specific deficiency of one or more OXPHOS complexes. Here, we report a 7-year-old Italian boy with childhood-onset rapidly progressive encephalomyopathy and stroke-like episodes. Multiple OXPHOS defects and decreased mtDNA copy number (40%) were detected in muscle homogenate. Clinical features combined with low level of plasma citrulline were highly suggestive of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, however, the common m.3243 A > G mutation was excluded. Targeted exome sequencing of genes encoding the mitochondrial proteome identified a damaging mutation, c.567 G > A, affecting a highly conserved amino acid residue (p.Gly189Arg) of the MRM2 protein. MRM2 has never before been linked to a human disease and encodes an enzyme responsible for 2’-O-methyl modification at position U1369 in the human mitochondrial 16S rRNA. We generated a knockout yeast model for the orthologous gene that showed a defect in respiration and the reduction of the 2’-O-methyl modification at the equivalent position (U2791) in the yeast mitochondrial 21S rRNA. Complementation with the mrm2 allele carrying the equivalent yeast mutation failed to rescue the respiratory phenotype, which was instead completely rescued by expressing the wild-type allele. Our findings establish that defective MRM2 causes a MELAS-like phenotype, and suggests the genetic screening of the MRM2 gene in patients with a m.3243 A > G negative MELAS-like presentation. PMID:28973171

Defective mitochondrial rRNA methyltransferase MRM2 causes MELAS-like clinical syndrome.

PubMed

Garone, Caterina; D'Souza, Aaron R; Dallabona, Cristina; Lodi, Tiziana; Rebelo-Guiomar, Pedro; Rorbach, Joanna; Donati, Maria Alice; Procopio, Elena; Montomoli, Martino; Guerrini, Renzo; Zeviani, Massimo; Calvo, Sarah E; Mootha, Vamsi K; DiMauro, Salvatore; Ferrero, Ileana; Minczuk, Michal

2017-11-01

Defects in nuclear-encoded proteins of the mitochondrial translation machinery cause early-onset and tissue-specific deficiency of one or more OXPHOS complexes. Here, we report a 7-year-old Italian boy with childhood-onset rapidly progressive encephalomyopathy and stroke-like episodes. Multiple OXPHOS defects and decreased mtDNA copy number (40%) were detected in muscle homogenate. Clinical features combined with low level of plasma citrulline were highly suggestive of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, however, the common m.3243 A > G mutation was excluded. Targeted exome sequencing of genes encoding the mitochondrial proteome identified a damaging mutation, c.567 G > A, affecting a highly conserved amino acid residue (p.Gly189Arg) of the MRM2 protein. MRM2 has never before been linked to a human disease and encodes an enzyme responsible for 2'-O-methyl modification at position U1369 in the human mitochondrial 16S rRNA. We generated a knockout yeast model for the orthologous gene that showed a defect in respiration and the reduction of the 2'-O-methyl modification at the equivalent position (U2791) in the yeast mitochondrial 21S rRNA. Complementation with the mrm2 allele carrying the equivalent yeast mutation failed to rescue the respiratory phenotype, which was instead completely rescued by expressing the wild-type allele. Our findings establish that defective MRM2 causes a MELAS-like phenotype, and suggests the genetic screening of the MRM2 gene in patients with a m.3243 A > G negative MELAS-like presentation. © The Author 2017. Published by Oxford University Press.

A defect in the TUSC3 gene is associated with autosomal recessive mental retardation.

PubMed

Garshasbi, Masoud; Hadavi, Valeh; Habibi, Haleh; Kahrizi, Kimia; Kariminejad, Roxana; Behjati, Farkhondeh; Tzschach, Andreas; Najmabadi, Hossein; Ropers, Hans Hilger; Kuss, Andreas Walter

2008-05-01

Recent studies have shown that autosomal recessive mental retardation (ARMR) is extremely heterogeneous, and there is reason to believe that the number of underlying gene defects goes into the thousands. To date, however, only four genes have been implicated in nonsyndromic ARMR (NS-ARMR): PRSS12 (neurotrypsin), CRBN (cereblon), CC2D1A, and GRIK2. As part of an ongoing systematic study aiming to identify ARMR genes, we investigated a large consanguineous family comprising seven patients with nonsyndromic ARMR in four sibships. Genome-wide SNP typing enabled us to map the relevant genetic defect to a 4.6 Mbp interval on chromosome 8. Haplotype analyses and copy-number studies led to the identification of a homozygous deletion partly removing TUSC3 (N33) in all patients. All obligate carriers of this family were heterozygous, but none of 192 unrelated healthy individuals from the same population carried this deletion. We excluded other disease-causing mutations in the coding regions of all genes within the linkage interval by sequencing; moreover, we verified the complete absence of a functional TUSC3 transcript in all patients through RT-PCR. TUSC3 is thought to encode a subunit of the endoplasmic reticulum-bound oligosaccharyltransferase complex that catalyzes a pivotal step in the protein N-glycosylation process. Our data suggest that in contrast to other genetic defects of glycosylation, inactivation of TUSC3 causes nonsyndromic MR, a conclusion that is supported by a separate report in this issue of AJHG. TUSC3 is only the fifth gene implicated in NS-ARMR and the first for which mutations have been reported in more than one family.

A Defect in the TUSC3 Gene Is Associated with Autosomal Recessive Mental Retardation

PubMed Central

Garshasbi, Masoud; Hadavi, Valeh; Habibi, Haleh; Kahrizi, Kimia; Kariminejad, Roxana; Behjati, Farkhondeh; Tzschach, Andreas; Najmabadi, Hossein; Ropers, Hans Hilger; Kuss, Andreas Walter

2008-01-01

Recent studies have shown that autosomal recessive mental retardation (ARMR) is extremely heterogeneous, and there is reason to believe that the number of underlying gene defects goes into the thousands. To date, however, only four genes have been implicated in nonsyndromic ARMR (NS-ARMR): PRSS12 (neurotrypsin), CRBN (cereblon), CC2D1A, and GRIK2. As part of an ongoing systematic study aiming to identify ARMR genes, we investigated a large consanguineous family comprising seven patients with nonsyndromic ARMR in four sibships. Genome-wide SNP typing enabled us to map the relevant genetic defect to a 4.6 Mbp interval on chromosome 8. Haplotype analyses and copy-number studies led to the identification of a homozygous deletion partly removing TUSC3 (N33) in all patients. All obligate carriers of this family were heterozygous, but none of 192 unrelated healthy individuals from the same population carried this deletion. We excluded other disease-causing mutations in the coding regions of all genes within the linkage interval by sequencing; moreover, we verified the complete absence of a functional TUSC3 transcript in all patients through RT-PCR. TUSC3 is thought to encode a subunit of the endoplasmic reticulum-bound oligosaccharyltransferase complex that catalyzes a pivotal step in the protein N-glycosylation process. Our data suggest that in contrast to other genetic defects of glycosylation, inactivation of TUSC3 causes nonsyndromic MR, a conclusion that is supported by a separate report in this issue of AJHG. TUSC3 is only the fifth gene implicated in NS-ARMR and the first for which mutations have been reported in more than one family. PMID:18452889

Spina Bifida: Pathogenesis, Mechanisms, and Genes in Mice and Humans

PubMed Central

Abou Chaar, Mohamad K.; Ahmad-Annuar, Azlina

2017-01-01

Spina bifida is among the phenotypes of the larger condition known as neural tube defects (NTDs). It is the most common central nervous system malformation compatible with life and the second leading cause of birth defects after congenital heart defects. In this review paper, we define spina bifida and discuss the phenotypes seen in humans as described by both surgeons and embryologists in order to compare and ultimately contrast it to the leading animal model, the mouse. Our understanding of spina bifida is currently limited to the observations we make in mouse models, which reflect complete or targeted knockouts of genes, which perturb the whole gene(s) without taking into account the issue of haploinsufficiency, which is most prominent in the human spina bifida condition. We thus conclude that the need to study spina bifida in all its forms, both aperta and occulta, is more indicative of the spina bifida in surviving humans and that the measure of deterioration arising from caudal neural tube defects, more commonly known as spina bifida, must be determined by the level of the lesion both in mouse and in man. PMID:28286691

Analysis of Craniocardiac Malformations in Xenopus using Optical Coherence Tomography

PubMed Central

Deniz, Engin; Jonas, Stephan; Hooper, Michael; N. Griffin, John; Choma, Michael A.; Khokha, Mustafa K.

2017-01-01

Birth defects affect 3% of children in the United States. Among the birth defects, congenital heart disease and craniofacial malformations are major causes of mortality and morbidity. Unfortunately, the genetic mechanisms underlying craniocardiac malformations remain largely uncharacterized. To address this, human genomic studies are identifying sequence variations in patients, resulting in numerous candidate genes. However, the molecular mechanisms of pathogenesis for most candidate genes are unknown. Therefore, there is a need for functional analyses in rapid and efficient animal models of human disease. Here, we coupled the frog Xenopus tropicalis with Optical Coherence Tomography (OCT) to create a fast and efficient system for testing craniocardiac candidate genes. OCT can image cross-sections of microscopic structures in vivo at resolutions approaching histology. Here, we identify optimal OCT imaging planes to visualize and quantitate Xenopus heart and facial structures establishing normative data. Next we evaluate known human congenital heart diseases: cardiomyopathy and heterotaxy. Finally, we examine craniofacial defects by a known human teratogen, cyclopamine. We recapitulate human phenotypes readily and quantify the functional and structural defects. Using this approach, we can quickly test human craniocardiac candidate genes for phenocopy as a critical first step towards understanding disease mechanisms of the candidate genes. PMID:28195132

Genes Required for Vacuolar Acidity in Saccharomyces Cerevisiae

PubMed Central

Preston, R. A.; Reinagel, P. S.; Jones, E. W.

1992-01-01

Mutations that cause loss of acidity in the vacuole (lysosome) of Saccharomyces cerevisiae were identified by screening colonies labeled with the fluorescent, pH-sensitive, vacuolar labeling agent, 6-carboxyfluorescein. Thirty nine vacuolar pH (Vph(-)) mutants were identified. Four of these contained mutant alleles of the previously described PEP3, PEP5, PEP6 and PEP7 genes. The remaining mutants defined eight complementation groups of vph mutations. No alleles of the VAT2 or TFP1 genes (known to encode subunits of the vacuolar H(+)-ATPase) were identified in the Vph(-) screen. Strains bearing mutations in any of six of the VPH genes failed to grow on medium buffered at neutral pH; otherwise, none of the vph mutations caused notable growth inhibition on standard yeast media. Expression of the vacuolar protease, carboxypeptidase Y, was defective in strains bearing vph4 mutations but was apparently normal in strains bearing any of the other vph mutations. Defects in vacuolar morphology at the light microscope level were evident in all Vph(-) mutants. Strains that contained representative mutant alleles of the 17 previously described PEP genes were assayed for vacuolar pH; mutations in seven of the PEP genes (including PEP3, PEP5, PEP6 and PEP7) caused loss of vacuolar acidity. PMID:1628805

Dictyostelium discoideum mutants with conditional defects in phagocytosis

PubMed Central

1994-01-01

We have isolated and characterized Dictyostelium discoideum mutants with conditional defects in phagocytosis. Under suspension conditions, the mutants exhibited dramatic reductions in the uptake of bacteria and polystyrene latex beads. The initial binding of these ligands was unaffected, however, indicating that the defect was not in a plasma membrane receptor: Because of the phagocytosis defect, the mutants were unable to grow when cultured in suspensions of heat-killed bacteria. The mutants exhibited normal capacities for fluid phase endocytosis and grew as rapidly as parental (AX4) cells in axenic medium. Both the defects in phagocytosis and growth on bacteria were corrected when the mutant Dictyostelium cells were cultured on solid substrates. Reversion and genetic complementation analysis suggested that the mutant phenotypes were caused by single gene defects. While the precise site of action of the mutations was not established, the mutations are likely to affect an early signaling event because the binding of bacteria to mutant cells in suspension was unable to trigger the localized polymerization of actin filaments required for ingestion; other aspects of actin function appeared normal. This class of conditional phagocytosis mutant should prove to be useful for the expression cloning of the affected gene(s). PMID:7519624

Laterality Defects Other Than Situs Inversus Totalis in Primary Ciliary Dyskinesia

PubMed Central

Davis, Stephanie D.; Ferkol, Thomas; Dell, Sharon D.; Rosenfeld, Margaret; Olivier, Kenneth N.; Sagel, Scott D.; Milla, Carlos; Zariwala, Maimoona A.; Wolf, Whitney; Carson, Johnny L.; Hazucha, Milan J.; Burns, Kimberlie; Robinson, Blair; Knowles, Michael R.; Leigh, Margaret W.

2014-01-01

BACKGROUND: Motile cilia dysfunction causes primary ciliary dyskinesia (PCD), situs inversus totalis (SI), and a spectrum of laterality defects, yet the prevalence of laterality defects other than SI in PCD has not been prospectively studied. METHODS: In this prospective study, participants with suspected PCD were referred to our multisite consortium. We measured nasal nitric oxide (nNO) level, examined cilia with electron microscopy, and analyzed PCD-causing gene mutations. Situs was classified as (1) situs solitus (SS), (2) SI, or (3) situs ambiguus (SA), including heterotaxy. Participants with hallmark electron microscopic defects, biallelic gene mutations, or both were considered to have classic PCD. RESULTS: Of 767 participants (median age, 8.1 years, range, 0.1-58 years), classic PCD was defined in 305, including 143 (46.9%), 125 (41.0%), and 37 (12.1%) with SS, SI, and SA, respectively. A spectrum of laterality defects was identified with classic PCD, including 2.6% and 2.3% with SA plus complex or simple cardiac defects, respectively; 4.6% with SA but no cardiac defect; and 2.6% with an isolated possible laterality defect. Participants with SA and classic PCD had a higher prevalence of PCD-associated respiratory symptoms vs SA control participants (year-round wet cough, P < .001; year-round nasal congestion, P = .015; neonatal respiratory distress, P = .009; digital clubbing, P = .021) and lower nNO levels (median, 12 nL/min vs 252 nL/min; P < .001). CONCLUSIONS: At least 12.1% of patients with classic PCD have SA and laterality defects ranging from classic heterotaxy to subtle laterality defects. Specific clinical features of PCD and low nNO levels help to identify PCD in patients with laterality defects. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT00323167; URL: www.clinicaltrials.gov PMID:24577564

Small heat shock proteins are necessary for heart migration and laterality determination in zebrafish

PubMed Central

Lahvic, Jamie L.; Ji, Yongchang; Marin, Paloma; Zuflacht, Jonah P.; Springel, Mark W.; Wosen, Jonathan E.; Davis, Leigh; Hutson, Lara D.; Amack, Jeffrey D.; Marvin, Martha J.

2013-01-01

Small heat shock proteins (sHsps) regulate cellular functions not only under stress, but also during normal development, when they are expressed in organ-specific patterns. Here we demonstrate that two small heat shock proteins expressed in embryonic zebrafish heart, hspb7 and hspb12, have roles in the development of left-right asymmetry. In zebrafish, laterality is determined by the motility of cilia in Kupffer’s vesicle (KV), where hspb7 is expressed; knockdown of hspb7 causes laterality defects by disrupting the motility of these cilia. In embryos with reduced hspb7, the axonemes of KV cilia have a 9+0 structure, while control embyros have a predominately 9+2 structure. Reduction of either hspb7 or hspb12 alters the expression pattern of genes that propagate the signals that establish left-right asymmetry: the nodal-related gene southpaw (spaw) in the lateral plate mesoderm, and its downstream targets pitx2, lefty1 and lefty2. Partial depletion of hspb7 causes concordant heart, brain and visceral laterality defects, indicating that loss of KV cilia motility leads causes coordinated but randomized laterality. Reducing hspb12 leads to similar alterations in the expression of downstream laterality genes, but at a lower penetrance. Simultaneous reduction of hspb7 and hspb12 randomizes heart, brain and visceral laterality, suggesting that these two genes have partially redundant functions in the establishment of left-right asymmetry. In addition, both hspb7 and hspb12 are expressed in the precardiac mesoderm and in the yolk syncytial layer, which supports the migration and fusion of mesodermal cardiac precursors. In embryos in which the reduction of hspb7 or hspb12 was limited to the yolk, migration defects predominated, suggesting that the yolk expression of these genes rather than heart expression is responsible for the migration defects. PMID:24140541

Mutations in the human GlyT2 gene define a presynaptic component of human startle disease

PubMed Central

Rees, Mark I.; Harvey, Kirsten; Pearce, Brian R.; Chung, Seo-Kyung; Duguid, Ian C.; Thomas, Philip; Beatty, Sarah; Graham, Gail E.; Armstrong, Linlea; Shiang, Rita; Abbott, Kim J.; Zuberi, Sameer M.; Stephenson, John B.P.; Owen, Michael J.; Tijssen, Marina A.J.; van den Maagdenberg, Arn M.J.M.; Smart, Trevor G.; Supplisson, Stéphane; Harvey, Robert J.

2011-01-01

Hyperekplexia is a human neurological disorder characterized by an excessive startle response and is typically caused by missense and nonsense mutations in the gene encoding the inhibitory glycine receptor (GlyR) α1 subunit (GLRA1)1-3. Genetic heterogeneity has been confirmed in isolated sporadic cases with mutations in other postsynaptic glycinergic proteins including the GlyR β subunit (GLRB)4, gephyrin (GPHN)5 and RhoGEF collybistin (ARHGEF9)6. However, many sporadic patients diagnosed with hyperekplexia do not carry mutations in these genes2-7. Here we reveal that missense, nonsense and frameshift mutations in the presynaptic glycine transporter 2 (GlyT2) gene (SLC6A5)8 also cause hyperekplexia. Patients harbouring mutations in SLC6A5 presented with hypertonia, an exaggerated startle response to tactile or acoustic stimuli, and life-threatening neonatal apnoea episodes. GlyT2 mutations result in defective subcellular localisation and/or decreased glycine uptake, with selected mutations affecting predicted glycine and Na+ binding sites. Our results demonstrate that SLC6A5 is a major gene for hyperekplexia and define the first neurological disorder linked to mutations in a Na+/Cl−-dependent transporter for a classical fast neurotransmitter. By analogy, we suggest that in other human disorders where defects in postsynaptic receptors have been identified, similar symptoms could result from defects in the cognate presynaptic neurotransmitter transporter. PMID:16751771

[Genetic obesity: new diagnostic options].

PubMed

de Vries, T I; Alsters, S I M; Kleinendorst, L; van Haaften, G; van der Zwaag, B; Van Haelst, M M

2017-01-01

- Obesity is an important risk factor for morbidity and premature death, as well as a contributing factor to psychosocial problems. The incidence of obesity has increased dramatically over the last few decades.- Obesity is considered to be a multifactorial condition in which both environmental factors and genetic factors play a part.- In approximately 5% of patients with morbid obesity, a monogenic cause can be identified. Mutations in the MC4R gene are the most frequently occurring monogenic cause of obesity.- The department of Genetics at the VU University Medical Center Amsterdam offers morbidly obese patients a diagnostic analysis of 50 obesity-associated genes. - An underlying obesity-associated genetic defect can influence patient response to certain treatments. Therefore, if the gene defect is known, it can be taken into account when considering treatment options.- The understanding of the genetics of obesity will significantly contribute to research into the development of personalized treatment options.

Dissecting the transcriptional phenotype of ribosomal protein deficiency: implications for Diamond-Blackfan Anemia

PubMed Central

Aspesi, Anna; Pavesi, Elisa; Robotti, Elisa; Crescitelli, Rossella; Boria, Ilenia; Avondo, Federica; Moniz, Hélène; Da Costa, Lydie; Mohandas, Narla; Roncaglia, Paola; Ramenghi, Ugo; Ronchi, Antonella; Gustincich, Stefano; Merlin, Simone; Marengo, Emilio; Ellis, Steven R.; Follenzi, Antonia; Santoro, Claudio; Dianzani, Irma

2014-01-01

Defects in genes encoding ribosomal proteins cause Diamond Blackfan Anemia (DBA), a red cell aplasia often associated with physical abnormalities. Other bone marrow failure syndromes have been attributed to defects in ribosomal components but the link between erythropoiesis and the ribosome remains to be fully defined. Several lines of evidence suggest that defects in ribosome synthesis lead to “ribosomal stress” with p53 activation and either cell cycle arrest or induction of apoptosis. Pathways independent of p53 have also been proposed to play a role in DBA pathogenesis. We took an unbiased approach to identify p53-independent pathways activated by defects in ribosome synthesis by analyzing global gene expression in various cellular models of DBA. Ranking-Principal Component Analysis (Ranking-PCA) was applied to the identified datasets to determine whether there are common sets of genes whose expression is altered in these different cellular models. We observed consistent changes in the expression of genes involved in cellular amino acid metabolic process, negative regulation of cell proliferation and cell redox homeostasis. These data indicate that cells respond to defects in ribosome synthesis by changing the level of expression of a limited subset of genes involved in critical cellular processes. Moreover, our data support a role for p53-independent pathways in the pathophysiology of DBA. PMID:24835311

Microarray mRNA expression analysis of Fanconi anemia fibroblasts.

PubMed

Galetzka, D; Weis, E; Rittner, G; Schindler, D; Haaf, T

2008-01-01

Fanconi anemia (FA) cells are generally hypersensitive to DNA cross-linking agents, implying that mutations in the different FANC genes cause a similar DNA repair defect(s). By using a customized cDNA microarray chip for DNA repair- and cell cycle-associated genes, we identified three genes, cathepsin B (CTSB), glutaredoxin (GLRX), and polo-like kinase 2 (PLK2), that were misregulated in untreated primary fibroblasts from three unrelated FA-D2 patients, compared to six controls. Quantitative real-time RT PCR was used to validate these results and to study possible molecular links between FA-D2 and other FA subtypes. GLRX was misregulated to opposite directions in a variety of different FA subtypes. Increased CTSB and decreased PLK2 expression was found in all or almost all of the analyzed complementation groups and, therefore, may be related to the defective FA pathway. Transcriptional upregulation of the CTSB proteinase appears to be a secondary phenomenon due to proliferation differences between FA and normal fibroblast cultures. In contrast, PLK2 is known to play a pivotal role in processes that are linked to FA defects and may contribute in multiple ways to the FA phenotype: PLK2 is a target gene for TP53, is likely to function as a tumor suppressor gene in hematologic neoplasia, and Plk2(-/-) mice are small because of defective embryonal development. (c) 2008 S. Karger AG, Basel.

INS-gene mutations: from genetics and beta cell biology to clinical disease.

PubMed

Liu, Ming; Sun, Jinhong; Cui, Jinqiu; Chen, Wei; Guo, Huan; Barbetti, Fabrizio; Arvan, Peter

2015-04-01

A growing list of insulin gene mutations causing a new form of monogenic diabetes has drawn increasing attention over the past seven years. The mutations have been identified in the untranslated regions of the insulin gene as well as the coding sequence of preproinsulin including within the signal peptide, insulin B-chain, C-peptide, insulin A-chain, and the proteolytic cleavage sites both for signal peptidase and the prohormone convertases. These mutations affect a variety of different steps of insulin biosynthesis in pancreatic beta cells. Importantly, although many of these mutations cause proinsulin misfolding with early onset autosomal dominant diabetes, some of the mutant alleles appear to engage different cellular and molecular mechanisms that underlie beta cell failure and diabetes. In this article, we review the most recent advances in the field and discuss challenges as well as potential strategies to prevent/delay the development and progression of autosomal dominant diabetes caused by INS-gene mutations. It is worth noting that although diabetes caused by INS gene mutations is rare, increasing evidence suggests that defects in the pathway of insulin biosynthesis may also be involved in the progression of more common types of diabetes. Collectively, the (pre)proinsulin mutants provide insightful molecular models to better understand the pathogenesis of all forms of diabetes in which preproinsulin processing defects, proinsulin misfolding, and ER stress are involved. Copyright © 2014 Elsevier Ltd. All rights reserved.

INS-gene mutations: From genetics and beta cell biology to clinical disease

PubMed Central

Liu, Ming; Sun, Jinhong; Cui, Jinqiu; Chen, Wei; Guo, Huan; Barbetti, Fabrizio; Arvan, Peter

2015-01-01

A growing list of insulin gene mutations causing a new form of monogenic diabetes has drawn increasing attention over the past seven years. The mutations have been identified in the untranslated regions of the insulin gene as well as the coding sequence of preproinsulin including within the signal peptide, insulin B-chain, C-peptide, insulin A-chain, and the proteolytic cleavage sites both for signal peptidase and the prohormone convertases. These mutations affect a variety of different steps of insulin biosynthesis in pancreatic beta cells. Importantly, although many of these mutations cause proinsulin misfolding with early onset autosomal dominant diabetes, some of the mutant alleles appear to engage different cellular and molecular mechanisms that underlie beta cell failure and diabetes. In this article, we review the most recent advances in the field and discuss challenges as well as potential strategies to prevent/delay the development and progression of autosomal dominant diabetes caused by INS-gene mutations. It is worth noting that although diabetes caused by INS gene mutations is rare, increasing evidence suggests that defects in the pathway of insulin biosynthesis may also be involved in the progression of more common types of diabetes. Collectively, the (pre)proinsulin mutants provide insightful molecular models to better understand the pathogenesis of all forms of diabetes in which preproinsulin processing defects, proinsulin misfolding, and ER stress are involved. PMID:25542748

An ortholog of farA of Aspergillus nidulans is implicated in the transcriptional activation of genes involved in fatty acid utilization in the yeast Yarrowia lipolytica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poopanitpan, Napapol; Kobayashi, Satoshi; Fukuda, Ryouichi

2010-11-26

Research highlights: {yields} POR1 is a Yarrowia lipolytica ortholog of farA involved in fatty acid response in A. nidulans. {yields} Deletion of POR1 caused growth defects on fatty acids. {yields} {Delta}por1 strain exhibited defects in the induction of genes involved in fatty acid utilization. -- Abstract: The yeast Yarrowia lipolytica effectively utilizes hydrophobic substrates such as fatty acids and n-alkanes. To identify a gene(s) regulating fatty acid utilization in Y. lipolytica, we first studied homologous genes to OAF1 and PIP2 of Saccharomyces cerevisiae, but their disruption did not change growth on oleic acid at all. We next characterized a Y.more » lipolytica gene, POR1 (primary oleate regulator 1), an ortholog of farA encoding a transcriptional activator that regulates fatty acid utilization in Aspergillus nidulans. The deletion mutant of POR1 was defective in the growth on various fatty acids, but not on glucose, glycerol, or n-hexadecane. It exhibited slight defect on n-decane. The transcriptional induction of genes involved in {beta}-oxidation and peroxisome proliferation by oleate was distinctly diminished in the {Delta}por1 strains. These data suggest that POR1 encodes a transcriptional activator widely regulating fatty acid metabolism in Y. lipolytica.« less

Fumonisin-nonproducing mutants exhibit differential expression of putative polyketide biosynthetic gene clusters in Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

The maize pathogen Fusarium verticillioides produces a group of polyketide derived secondary metabolites called fumonisins. Fumonisins can cause diseases in animals, and have been correlated epidemiologically with esophageal cancer and birth defects in humans. The fumonisin biosynthetic gene clust...

Altered expression of polyketide biosynthetic gene clusters in fumonisin-deficient mutants of Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

Fusarium verticillioides is a pathogen of maize and produces fumonisins, a group of polyketide derived secondary metabolites. Fumonisins cause diseases in animals, and they have been correlated epidemiologically with esophageal cancer and birth defects in humans. Fumonisin biosynthetic genes are c...

Genes Important for Schizosaccharomyces pombe Meiosis Identified Through a Functional Genomics Screen

PubMed Central

Blyth, Julie; Makrantoni, Vasso; Barton, Rachael E.; Spanos, Christos; Rappsilber, Juri; Marston, Adele L.

2018-01-01

Meiosis is a specialized cell division that generates gametes, such as eggs and sperm. Errors in meiosis result in miscarriages and are the leading cause of birth defects; however, the molecular origins of these defects remain unknown. Studies in model organisms are beginning to identify the genes and pathways important for meiosis, but the parts list is still poorly defined. Here we present a comprehensive catalog of genes important for meiosis in the fission yeast, Schizosaccharomyces pombe. Our genome-wide functional screen surveyed all nonessential genes for roles in chromosome segregation and spore formation. Novel genes important at distinct stages of the meiotic chromosome segregation and differentiation program were identified. Preliminary characterization implicated three of these genes in centrosome/spindle pole body, centromere, and cohesion function. Our findings represent a near-complete parts list of genes important for meiosis in fission yeast, providing a valuable resource to advance our molecular understanding of meiosis. PMID:29259000

No turning, a mouse mutation causing left-right and axial patterning defects.

PubMed

Melloy, P G; Ewart, J L; Cohen, M F; Desmond, M E; Kuehn, M R; Lo, C W

1998-01-01

Patterning along the left/right axes helps establish the orientation of visceral organ asymmetries, a process which is of fundamental importance to the viability of an organism. A linkage between left/right and axial patterning is indicated by the finding that a number of genes involved in left/right patterning also play a role in anteroposterior and dorsoventral patterning. We have recovered a spontaneous mouse mutation causing left/right patterning defects together with defects in anteroposterior and dorsoventral patterning. This mutation is recessive lethal and was named no turning (nt) because the mutant embryos fail to undergo embryonic turning. nt embryos exhibit cranial neural tube closure defects and malformed somites and are caudally truncated. Development of the heart arrests at the looped heart tube stage, with cardiovascular defects indicated by ballooning of the pericardial sac and the pooling of blood in various regions of the embryo. Interestingly, in nt embryos, the direction of heart looping was randomized. Nodal and lefty, two genes that are normally expressed only in the left lateral plate mesoderm, show expression in the right and left lateral plate mesoderm. Lefty, which is normally also expressed in the floorplate, is not found in the prospective floor plate of nt embryos. This suggests the possibility of notochordal defects. This was confirmed by histological analysis and the examination of sonic hedgehog, Brachyury, and HNF-3 beta gene expression. These studies showed that the notochord is present in the early nt embryo, but degenerates as development progresses. Overall, these findings support the hypothesis that the notochord plays an active role in left/right patterning. Our results suggest that nt may participate in this process by modulating the notochordal expression of HNF-3 beta.

May 2006 update in porphobilinogen deaminase gene polymorphisms and mutations causing acute intermittent porphyria: comparison with the situation in Slavic population.

PubMed

Hrdinka, M; Puy, H; Martasek, P

2006-01-01

Acute intermittent porphyria (AIP) is an autosomal dominant disorder of heme biosynthesis caused by molecular defects in the porphobilinogen deaminase (PBGD) gene. This paper reviews published mutations, their types, and polymorphisms within the PBGD gene. To date, 301 different mutations and 21 polymorphisms have been identified in the PBGD gene in AIP patients and individuals from various countries and ethnic groups. During the search for mutations identified among Slavic AIP patients we found 65 such mutations and concluded that there is not a distinct predominance of certain mutations in Slavs.

Defective minor spliceosome mRNA processing results in isolated familial growth hormone deficiency

PubMed Central

Argente, Jesús; Flores, Raquel; Gutiérrez-Arumí, Armand; Verma, Bhupendra; Martos-Moreno, Gabriel Á; Cuscó, Ivon; Oghabian, Ali; Chowen, Julie A; Frilander, Mikko J; Pérez-Jurado, Luis A

2014-01-01

The molecular basis of a significant number of cases of isolated growth hormone deficiency remains unknown. We describe three sisters affected with severe isolated growth hormone deficiency and pituitary hypoplasia caused by biallelic mutations in the RNPC3 gene, which codes for a minor spliceosome protein required for U11/U12 small nuclear ribonucleoprotein (snRNP) formation and splicing of U12-type introns. We found anomalies in U11/U12 di-snRNP formation and in splicing of multiple U12-type introns in patient cells. Defective transcripts include preprohormone convertases SPCS2 and SPCS3 and actin-related ARPC5L genes, which are candidates for the somatotroph-restricted dysfunction. The reported novel mechanism for familial growth hormone deficiency demonstrates that general mRNA processing defects of the minor spliceosome can lead to very narrow tissue-specific consequences. Subject Categories Genetics, Gene Therapy ' Genetic Disease; Metabolism PMID:24480542

[Short stature caused by SHOX gene haploinsufficiency: from diagnosis to treatment].

PubMed

Jorge, Alexander A L; Nishi, Mirian Y; Funari, Mariana F A; Souza, Silvia C; Arnhold, Ivo J P; Mendonça, Berenice B

2008-07-01

Studies involving patients with short stature and partial deletion of sex chromosomes identified SHOX gene in the pseudoautosomal region of the X and Y chromosomes. SHOX haploinsufficiency is an important cause of short stature in a diversity of clinical conditions. It explains 2/3 of short stature observed in Turner syndrome (TS) patients. Heterozygous mutations in SHOX are observed in 77% of patients with Leri-Weill dyschondrosteosis, a common dominant inherited skeletal dysplasia and in 3% of children with idiopathic short stature, indicating that SHOX defects are the most frequent monogenetic cause of short stature. The sitting height/height ratio (SH/H) standard deviation score is a simple way to assess body proportions and together with a careful exam of other family members, effectively selected a group of patients that presented a high frequency of SHOX mutations. Growth hormone treatment of short stature due to TS is well established and considering the common etiology of short stature in patients with isolated defects of SHOX gene, this treatment is also proposed for these patients. Here, we review clinical, molecular and therapeutic aspects of SHOX haploinsufficiency.

[SOX2 defect and anophthalmia and microphthalmia].

PubMed

Ye, Fu-xiang; Fan, Xian-qun

2012-11-01

As a severe congenital developmental disorder, anophthalmia and microphthalmia are usually accompanied with vision impairment and hypoevolutism of the orbit in the affected side. Many genes are involved in anophthalmia and microphthalmia, in which, SOX2 is an important one. The defect of SOX2 causes multiple system disorders, including anophthalmia and microphthalmia. We describe the relationship between the SOX2 defect and anophthalmia/microphthalmia, in order to offer some proposals for the differential diagnosis, treatment and research of anophthalmia and microphthalmia.

Delayed Induction of Human NTE (PNPLA6) Rescues Neurodegeneration and Mobility Defects of Drosophila swiss cheese (sws) Mutants.

PubMed

Sujkowski, Alyson; Rainier, Shirley; Fink, John K; Wessells, Robert J

2015-01-01

Human PNPLA6 gene encodes Neuropathy Target Esterase protein (NTE). PNPLA6 gene mutations cause hereditary spastic paraplegia (SPG39 HSP), Gordon-Holmes syndrome, Boucher-Neuhäuser syndromes, Laurence-Moon syndrome, and Oliver-McFarlane syndrome. Mutations in the Drosophila NTE homolog swiss cheese (sws) cause early-onset, progressive behavioral defects and neurodegeneration characterized by vacuole formation. We investigated sws5 flies and show for the first time that this allele causes progressive vacuolar formation in the brain and progressive deterioration of negative geotaxis speed and endurance. We demonstrate that inducible, neuron-specific expression of full-length human wildtype NTE reduces vacuole formation and substantially rescues mobility. Indeed, neuron-specific expression of wildtype human NTE is capable of rescuing mobility defects after 10 days of adult life at 29°C, when significant degeneration has already occurred, and significantly extends longevity of mutants at 25°C. These results raise the exciting possibility that late induction of NTE function may reduce or ameliorate neurodegeneration in humans even after symptoms begin. In addition, these results highlight the utility of negative geotaxis endurance as a new assay for longitudinal tracking of degenerative phenotypes in Drosophila.

Long Term Prognosis

MedlinePlus

... with further research. Until researchers can identify the exact gene causing cardiomyopathy, there is no known way ... that it is not a practical or reasonable solution since it would involve removing a defective protein ...

A Mitocentric View of Parkinson’s Disease

PubMed Central

Haelterman, Nele A.; Yoon, Wan Hee; Sandoval, Hector; Jaiswal, Manish; Shulman, Joshua M.; Bellen, Hugo J.

2015-01-01

Parkinson’s disease (PD) is a common neurodegenerative disease, yet the underlying causative molecular mechanisms are ill defined. Numerous observations based on drug studies and mutations in genes that cause PD point to a complex set of rather subtle mitochondrial defects that may be causative. Indeed, intensive investigation of these genes in model organisms has revealed roles in the electron transport chain, mitochondrial protein homeostasis, mitophagy, and the fusion and fission of mitochondria. Here, we attempt to synthesize results from experimental studies in diverse systems to define the precise function of these PD genes, as well as their interplay with other genes that affect mitochondrial function. We propose that subtle mitochondrial defects in combination with other insults trigger the onset and progression of disease, in both familial and idiopathic PD. PMID:24821430

Transient Early Embryonic Expression of Nkx2-5 Mutations Linked to Congenital Heart Defects in Human Causes Heart Defects in Xenopus laevis

PubMed Central

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

DNA methylation abnormalities in congenital heart disease.

PubMed

Serra-Juhé, Clara; Cuscó, Ivon; Homs, Aïda; Flores, Raquel; Torán, Núria; Pérez-Jurado, Luis A

2015-01-01

Congenital heart defects represent the most common malformation at birth, occurring also in ∼50% of individuals with Down syndrome. Congenital heart defects are thought to have multifactorial etiology, but the main causes are largely unknown. We have explored the global methylation profile of fetal heart DNA in comparison to blood DNA from control subjects: an absolute correlation with the type of tissue was detected. Pathway analysis revealed a significant enrichment of differential methylation at genes related to muscle contraction and cardiomyopathies in the developing heart DNA. We have also searched for abnormal methylation profiles on developing heart-tissue DNA of syndromic and non-syndromic congenital heart defects. On average, 3 regions with aberrant methylation were detected per sample and 18 regions were found differentially methylated between groups. Several epimutations were detected in candidate genes involved in growth regulation, apoptosis and folate pathway. A likely pathogenic hypermethylation of several intragenic sites at the MSX1 gene, involved in outflow tract morphogenesis, was found in a fetus with isolated heart malformation. In addition, hypermethylation of the GATA4 gene was present in fetuses with Down syndrome with or without congenital heart defects, as well as in fetuses with isolated heart malformations. Expression deregulation of the abnormally methylated genes was detected. Our data indicate that epigenetic alterations of relevant genes are present in developing heart DNA in fetuses with both isolated and syndromic heart malformations. These epimutations likely contribute to the pathogenesis of the malformation by cis-acting effects on gene expression.

Responsiveness to a Physiological Regimen of GnRH Therapy and Relation to Genotype in Women With Isolated Hypogonadotropic Hypogonadism

PubMed Central

Abel, Brent S.; Shaw, Natalie D.; Brown, Jenifer M.; Adams, Judith M.; Alati, Teresa; Martin, Kathryn A.; Pitteloud, Nelly; Seminara, Stephanie B.; Plummer, Lacey; Pignatelli, Duarte; Crowley, William F.; Welt, Corrine K.

2013-01-01

Context: Isolated hypogonadotropic hypogonadism (IHH) is caused by defective GnRH secretion or action resulting in absent or incomplete pubertal development and infertility. Most women with IHH ovulate with physiological GnRH replacement, implicating GnRH deficiency as the etiology. However, a subset does not respond normally, suggesting the presence of defects at the pituitary or ovary. Objectives: The objective of the study was to unmask pituitary or ovarian defects in IHH women using a physiological regimen of GnRH replacement, relating these responses to genes known to cause IHH. Design, Setting, and Subjects: This study is a retrospective analysis of 37 IHH women treated with iv pulsatile GnRH (75 ng/kg per bolus). Main Outcome Measures: Serum gonadotropin and sex steroid levels were measured, and 14 genes implicated in IHH were sequenced. Results: During their first cycle of GnRH replacement, normal cycles were recreated in 60% (22 of 37) of IHH women. Thirty percent of women (12 of 37) demonstrated an attenuated gonadotropin response, indicating pituitary resistance, and 10% (3 of 37) exhibited an exaggerated FSH response, consistent with ovarian resistance. Mutations in CHD7, FGFR1, KAL1, TAC3, and TACR3 were documented in IHH women with normal cycles, whereas mutations were identified in GNRHR, PROKR2, and FGFR1 in those with pituitary resistance. Women with ovarian resistance were mutation negative. Conclusions: Although physiological replacement with GnRH recreates normal menstrual cycle dynamics in most IHH women, hypogonadotropic responses in the first week of treatment identify a subset of women with pituitary dysfunction, only some of whom have mutations in GNRHR. IHH women with hypergonadotropic responses to GnRH replacement, consistent with an additional ovarian defect, did not have mutations in genes known to cause IHH, similar to our findings in a subset of IHH men with evidence of an additional testicular defect. PMID:23341491

Selection of Salmonella enterica Serovar Typhi Genes Involved during Interaction with Human Macrophages by Screening of a Transposon Mutant Library

PubMed Central

Sabbagh, Sébastien C.; Lepage, Christine; McClelland, Michael; Daigle, France

2012-01-01

The human-adapted Salmonella enterica serovar Typhi (S. Typhi) causes a systemic infection known as typhoid fever. This disease relies on the ability of the bacterium to survive within macrophages. In order to identify genes involved during interaction with macrophages, a pool of approximately 105 transposon mutants of S. Typhi was subjected to three serial passages of 24 hours through human macrophages. Mutants recovered from infected macrophages (output) were compared to the initial pool (input) and those significantly underrepresented resulted in the identification of 130 genes encoding for cell membrane components, fimbriae, flagella, regulatory processes, pathogenesis, and many genes of unknown function. Defined deletions in 28 genes or gene clusters were created and mutants were evaluated in competitive and individual infection assays for uptake and intracellular survival during interaction with human macrophages. Overall, 26 mutants had defects in the competitive assay and 14 mutants had defects in the individual assay. Twelve mutants had defects in both assays, including acrA, exbDB, flhCD, fliC, gppA, mlc, pgtE, typA, waaQGP, SPI-4, STY1867-68, and STY2346. The complementation of several mutants by expression of plasmid-borne wild-type genes or gene clusters reversed defects, confirming that the phenotypic impairments within macrophages were gene-specific. In this study, 35 novel phenotypes of either uptake or intracellular survival in macrophages were associated with Salmonella genes. Moreover, these results reveal several genes encoding molecular mechanisms not previously known to be involved in systemic infection by human-adapted typhoidal Salmonella that will need to be elucidated. PMID:22574205

The Role of Hox Genes in Female Reproductive Tract Development, Adult Function, and Fertility.

PubMed

Du, Hongling; Taylor, Hugh S

2015-11-09

HOX genes convey positional identity that leads to the proper partitioning and adult identity of the female reproductive track. Abnormalities in reproductive tract development can be caused by HOX gene mutations or altered HOX gene expression. Diethylstilbestrol (DES) and other endocrine disruptors cause Müllerian defects by changing HOX gene expression. HOX genes are also essential regulators of adult endometrial development. Regulated HOXA10 and HOXA11 expression is necessary for endometrial receptivity; decreased HOXA10 or HOXA11 expression leads to decreased implantation rates. Alternation of HOXA10 and HOXA11 expression has been identified as a mechanism of the decreased implantation associated with endometriosis, polycystic ovarian syndrome, leiomyoma, polyps, adenomyosis, and hydrosalpinx. Alteration of HOX gene expression causes both uterine developmental abnormalities and impaired adult endometrial development that prevent implantation and lead to female infertility. Copyright © 2016 Cold Spring Harbor Laboratory Press; all rights reserved.

ENU Mutagenesis in Mice Identifies Candidate Genes For Hypogonadism

PubMed Central

Weiss, Jeffrey; Hurley, Lisa A.; Harris, Rebecca M.; Finlayson, Courtney; Tong, Minghan; Fisher, Lisa A.; Moran, Jennifer L.; Beier, David R.; Mason, Christopher; Jameson, J. Larry

2012-01-01

Genome-wide mutagenesis was performed in mice to identify candidate genes for male infertility, for which the predominant causes remain idiopathic. Mice were mutagenized using N-ethyl-N-nitrosourea (ENU), bred, and screened for phenotypes associated with the male urogenital system. Fifteen heritable lines were isolated and chromosomal loci were assigned using low density genome-wide SNP arrays. Ten of the fifteen lines were pursued further using higher resolution SNP analysis to narrow the candidate gene regions. Exon sequencing of candidate genes identified mutations in mice with cystic kidneys (Bicc1), cryptorchidism (Rxfp2), restricted germ cell deficiency (Plk4), and severe germ cell deficiency (Prdm9). In two other lines with severe hypogonadism candidate sequencing failed to identify mutations, suggesting defects in genes with previously undocumented roles in gonadal function. These genomic intervals were sequenced in their entirety and a candidate mutation was identified in SnrpE in one of the two lines. The line harboring the SnrpE variant retains substantial spermatogenesis despite small testis size, an unusual phenotype. In addition to the reproductive defects, heritable phenotypes were observed in mice with ataxia (Myo5a), tremors (Pmp22), growth retardation (unknown gene), and hydrocephalus (unknown gene). These results demonstrate that the ENU screen is an effective tool for identifying potential causes of male infertility. PMID:22258617

A novel mutation in DDR2 causing spondylo-meta-epiphyseal dysplasia with short limbs and abnormal calcifications (SMED-SL) results in defective intra-cellular trafficking.

PubMed

Al-Kindi, Adila; Kizhakkedath, Praseetha; Xu, Huifang; John, Anne; Sayegh, Abeer Al; Ganesh, Anuradha; Al-Awadi, Maha; Al-Anbouri, Lamya; Al-Gazali, Lihadh; Leitinger, Birgit; Ali, Bassam R

2014-04-11

The rare autosomal genetic disorder, Spondylo-meta-epiphyseal dysplasia with short limbs and abnormal calcifications (SMED-SL), is reported to be caused by missense or splice site mutations in the human discoidin domain receptor 2 (DDR2) gene. Previously our group has established that trafficking defects and loss of ligand binding are the underlying cellular mechanisms of several SMED-SL causing mutations. Here we report the clinical characteristics of two siblings of consanguineous marriage with suspected SMED-SL and identification of a novel disease-causing mutation in the DDR2 gene. Clinical evaluation and radiography were performed to evaluate the patients. All the coding exons and splice sites of the DDR2 gene were sequenced by Sanger sequencing. Subcellular localization of the mutated DDR2 protein was determined by confocal microscopy, deglycosylation assay and Western blotting. DDR2 activity was measured by collagen activation and Western analysis. In addition to the typical features of SMED-SL, one of the patients has an eye phenotype including visual impairment due to optic atrophy. DNA sequencing revealed a novel homozygous dinucleotide deletion mutation (c.2468_2469delCT) on exon 18 of the DDR2 gene in both patients. The mutation resulted in a frameshift leading to an amino acid change at position S823 and a predicted premature termination of translation (p.S823Cfs*2). Subcellular localization of the mutant protein was analyzed in mammalian cell lines, and it was found to be largely retained in the endoplasmic reticulum (ER), which was further supported by its N-glycosylation profile. In keeping with its cellular mis-localization, the mutant protein was found to be deficient in collagen-induced receptor activation, suggesting protein trafficking defects as the major cellular mechanism underlying the loss of DDR2 function in our patients. Our results indicate that the novel mutation results in defective trafficking of the DDR2 protein leading to loss of function and disease. This confirms our previous findings that DDR2 missense mutations occurring at the kinase domain result in retention of the mutant protein in the ER.

Disruption of the Arabidopsis CGI-58 homologue produces Chanarin-Dorfman-like lipodystrophy in plants

USDA-ARS?s Scientific Manuscript database

CGI-58 is the defective gene in the human neutral lipid storage disease called Chanarin-Dorfman syndrome. This disorder causes intracellular lipid droplets to accumulate in nonadipose tissues, such as skin and blood cells. Here, disruption of the homologous CGI-58 gene in Arabidopsis thaliana result...

The Chromatin Remodeler BPTF Activates a Stemness Gene-Expression Program Essential for the Maintenance of Adult Hematopoietic Stem Cells.

PubMed

Xu, Bowen; Cai, Ling; Butler, Jason M; Chen, Dongliang; Lu, Xiongdong; Allison, David F; Lu, Rui; Rafii, Shahin; Parker, Joel S; Zheng, Deyou; Wang, Gang Greg

2018-03-13

Self-renewal and differentiation of adult stem cells are tightly regulated partly through configuration of chromatin structure by chromatin remodelers. Using knockout mice, we here demonstrate that bromodomain PHD finger transcription factor (BPTF), a component of the nucleosome remodeling factor (NURF) chromatin-remodeling complex, is essential for maintaining the population size of hematopoietic stem/progenitor cells (HSPCs), including long-term hematopoietic stem cells (HSCs). Bptf-deficient HSCs are defective in reconstituted hematopoiesis, and hematopoietic-specific knockout of Bptf caused profound defects including bone marrow failure and anemia. Genome-wide transcriptome profiling revealed that BPTF loss caused downregulation of HSC-specific gene-expression programs, which contain several master transcription factors (Meis1, Pbx1, Mn1, and Lmo2) required for HSC maintenance and self-renewal. Furthermore, we show that BPTF potentiates the chromatin accessibility of key HSC "stemness" genes. These results demonstrate an essential requirement of the chromatin remodeler BPTF and NURF for activation of "stemness" gene-expression programs and proper function of adult HSCs. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Isolated cryptorchidism: no evidence for involvement of genes underlying isolated hypogonadotropic hypogonadism.

PubMed

Laitinen, Eeva-Maria; Tommiska, Johanna; Virtanen, Helena E; Oehlandt, Heidi; Koivu, Rosanna; Vaaralahti, Kirsi; Toppari, Jorma; Raivio, Taneli

2011-07-20

Mutations in FGFR1, GNRHR, PROK2, PROKR2, TAC3, or TACR3 underlie isolated hypogonadotropic hypogonadism (IHH) with clinically variable phenotypes, and, by causing incomplete intrauterine activation of the hypothalamic-pituitary-gonadal axis, may lead to cryptorchidism. To investigate the role of defects in these genes in the etiology of isolated cryptorchidism, we screened coding exons and exon-intron boundaries of these genes in 54 boys or men from 46 families with a history of cryptorchidism. Control subjects (200) included 120 males. None of the patients carried mutation(s) in FGFR1, PROK2, PROKR2, TAC3 or TACR3. Two of the 46 index subjects with unilateral cryptorchidism were heterozygous carriers of a single GNRHR mutation (Q106R or R262Q), also present in male controls with a similar frequency (3/120; p=0.62). No homozygous or compound heterozygous GNRHR mutations were found. In conclusion, cryptorchidism is not commonly caused by defects in genes involved in IHH. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Defects in the C. elegans acyl-CoA Synthase, acs-3, and Nuclear Hormone Receptor, nhr-25, Cause Sensitivity to Distinct, but Overlapping Stresses

PubMed Central

Ward, Jordan D.; Mullaney, Brendan; Schiller, Benjamin J.; He, Le D.; Petnic, Sarah E.; Couillault, Carole; Pujol, Nathalie; Bernal, Teresita U.; Van Gilst, Marc R.; Ashrafi, Kaveh; Ewbank, Jonathan J.; Yamamoto, Keith R.

2014-01-01

Metazoan transcription factors control distinct networks of genes in specific tissues, yet understanding how these networks are integrated into physiology, development, and homeostasis remains challenging. Inactivation of the nuclear hormone receptor nhr-25 ameliorates developmental and metabolic phenotypes associated with loss of function of an acyl-CoA synthetase gene, acs-3. ACS-3 activity prevents aberrantly high NHR-25 activity. Here, we investigated this relationship further by examining gene expression patterns following acs-3 and nhr-25 inactivation. Unexpectedly, we found that the acs-3 mutation or nhr-25 RNAi resulted in similar transcriptomes with enrichment in innate immunity and stress response gene expression. Mutants of either gene exhibited distinct sensitivities to pathogens and environmental stresses. Only nhr-25 was required for wild-type levels of resistance to the bacterial pathogen P. aeruginosa and only acs-3 was required for wild-type levels of resistance to osmotic stress and the oxidative stress generator, juglone. Inactivation of either acs-3 or nhr-25 compromised lifespan and resistance to the fungal pathogen D. coniospora. Double mutants exhibited more severe defects in the lifespan and P. aeruginosa assays, but were similar to the single mutants in other assays. Finally, acs-3 mutants displayed defects in their epidermal surface barrier, potentially accounting for the observed sensitivities. Together, these data indicate that inactivation of either acs-3 or nhr-25 causes stress sensitivity and increased expression of innate immunity/stress genes, most likely by different mechanisms. Elevated expression of these immune/stress genes appears to abrogate the transcriptional signatures relevant to metabolism and development. PMID:24651852

Outer membrane defect and stronger biofilm formation caused by inactivation of a gene encoding for heptosyltransferase I in Cronobacter sakazakii ATCC BAA-894.

PubMed

Wang, L; Hu, X; Tao, G; Wang, X

2012-05-01

To investigate the role of lipopolysaccharide (LPS) structure in the stability of outer membrane and the ability of biofilm formation in Cronobacter sakazakii. A C. sakazakii mutant strain LWW02 was constructed by inactivating the gene ESA_04107 encoding for heptosyltransferase I. LPS were purified from LWW02, and changes in their structure were confirmed by thin-layer chromatography and electrospray ionization mass spectrometry. Comparing with the wild-type strain BAA-894, slower growth, higher membrane permeability, higher surface hydrophobicity, stronger ability of autoaggregation and biofilm formation were observed for the mutant strain LWW02. The gene ESA_04107 encodes heptosyltransferase I in C. sakazakii ATCC BAA-894. The cleavage of LPS in C. sakazakii could cause its outer membrane defects and increase its ability to form biofilms. The study is important for understanding the pathogenic mechanism and efficient control of C. sakazakii. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

More than a bystander: the contributions of intrinsic skeletal muscle defects in motor neuron diseases

PubMed Central

Boyer, Justin G.; Ferrier, Andrew; Kothary, Rashmi

2013-01-01

Spinal muscular atrophy (SMA), amyotrophic lateral sclerosis (ALS), and spinal-bulbar muscular atrophy (SBMA) are devastating diseases characterized by the degeneration of motor neurons. Although the molecular causes underlying these diseases differ, recent findings have highlighted the contribution of intrinsic skeletal muscle defects in motor neuron diseases. The use of cell culture and animal models has led to the important finding that muscle defects occur prior to and independently of motor neuron degeneration in motor neuron diseases. In SMA for instance, the muscle specific requirements of the SMA disease-causing gene have been demonstrated by a series of genetic rescue experiments in SMA models. Conditional ALS mouse models expressing a muscle specific mutant SOD1 gene develop atrophy and muscle degeneration in the absence of motor neuron pathology. Treating SBMA mice by over-expressing IGF-1 in a skeletal muscle-specific manner attenuates disease severity and improves motor neuron pathology. In the present review, we provide an in depth description of muscle intrinsic defects, and discuss how they impact muscle function in these diseases. Furthermore, we discuss muscle-specific therapeutic strategies used to treat animal models of SMA, ALS, and SBMA. The study of intrinsic skeletal muscle defects is crucial for the understanding of the pathophysiology of these diseases and will open new therapeutic options for the treatment of motor neuron diseases. PMID:24391590

Restoring balance to B cells in ADA deficiency.

PubMed

Luning Prak, Eline T

2012-06-01

It is paradoxical that immunodeficiency disorders are associated with autoimmunity. Adenosine deaminase (ADA) deficiency, a cause of X-linked severe combined immunodeficiency (SCID), is a case in point. In this issue of the JCI, Sauer and colleagues investigate the B cell defects in ADA-deficient patients. They demonstrate that ADA patients receiving enzyme replacement therapy had B cell tolerance checkpoint defects. Remarkably, gene therapy with a retrovirus that expresses ADA resulted in the apparent correction of these defects, with normalization of peripheral B cell autoantibody frequencies. In vitro, agents that either block ADA or overexpress adenosine resulted in altered B cell receptor and TLR signaling. Collectively, these data implicate a B cell-intrinsic mechanism for alterations in B cell tolerance in the setting of partial ADA deficiency that is corrected by gene therapy.

Genetics Home Reference: Rothmund-Thomson syndrome

MedlinePlus

... syndromes are also characterized by radial ray defects, skeletal abnormalities, and slow growth. All of these conditions can be caused by mutations in the same gene. Based on these similarities, researchers are investigating whether ...

Exclusion of MYF5, GSC, RUNX2, and TCOF1 mutation in a case of cerebro-costo-mandibular syndrome.

PubMed

Su, Pen-Hua; Chen, Jia-Yuh; Chiang, Chin-Lung; Ng, Yan-Yan; Chen, Suh-Jen

2010-04-01

Cerebro-costo-mandibular syndrome (CCMS) is an uncommon multiple congenital anomaly syndrome characterized by severe micrognathia, posterior rib-gap defects, and developmental delay. The cause of CCMS is unknown. Genes hypothesized to have a causal role in CCMS, include myogenic factor 5 (MYF5), goosecoid homeobox (GSC) and runt-related transcription factor 2 (RUNX2) [formerly known as core-binding factor (CBFA1)]. We report an infant with typical features of CCMS who, on prenatal ultrasound, was found to have severe micrognathia. We present the first image by three-dimensional computed tomography of posterior rib-defect, and we exclude mutations of the MYF5, GSC, RUNX2, and TCOF1 genes in our patient. Further molecular studies are needed to evaluate the cause of CCMS.

Pharmacogenetics of cystic fibrosis treatment.

PubMed

Carter, Suzanne C; McKone, Edward F

2016-08-01

Cystic fibrosis (CF) is genetic autosomal recessive disease caused by reduced or absent function of CFTR protein. Treatments for patients with CF have primarily focused on the downstream end-organ consequences of defective CFTR. Since the discovery of the CFTR gene that causes CF in 1989 there have been tremendous advances in our understanding of the genetics and pathophysiology of CF. This has recently led to the development of new CFTR mutation-specific targeted therapies for select patients with CF. This review will discuss the characteristics of the CFTR gene, the CFTR mutations that cause CF and the new mutation specific pharmacological treatments including gene therapy that are contributing to the dawning of a new era in cystic fibrosis care.

Xeroderma pigmentosum: diagnostic procedures, interdisciplinary patient care, and novel therapeutic approaches.

PubMed

Lehmann, Janin; Schubert, Steffen; Emmert, Steffen

2014-10-01

Xeroderma pigmentosum (XP) is an autosomal recessive disease, caused by a gene defect in the nucleotide-excision-repair (NER) pathway or in translesional DNA synthesis. At the age of eight, patients already develop their first skin cancers due to this DNA repair defect. In contrast, in the Caucasian population the first tumor formation in UV exposed skin regions occurs at a mean age of 60. The clinical picture among patients suffering from XP is highly diverse and includes signs of accelerated skin aging, and UV-induced skin cancers, as well as ophthalmologic and neurological symptoms. Patients should therefore receive interdisciplinary care. This includes dermatologists, ophthalmologists, ENT specialists, neurologists, and human geneticists. Patients with XP are clinically diagnosed, but this may be supported by molecular-genetic and functional analyses. These analyses allow pinpointing the exact disease-causing gene defect (complementation group assignment, detection of the type and location of the mutation within the gene). The resulting information is already relevant to predict the course of disease and symptoms and probably will be utilized for individualized therapeutic approaches in the future. Recently, enhanced repair of UV photolesions in xeroderma pigmentosum group C cells induced by translational readthrough of premature termination codons by certain antibiotics could be demonstrated. © 2014 Deutsche Dermatologische Gesellschaft (DDG). Published by John Wiley & Sons Ltd.

Molecular Diagnostics of Copper-Transporting Protein Mutations Allows Early Onset Individual Therapy of Menkes Disease.

PubMed

Králík, L; Flachsová, E; Hansíková, H; Saudek, V; Zeman, J; Martásek, P

2017-01-01

Menkes disease is a severe X-linked recessive disorder caused by a defect in the ATP7A gene, which encodes a membrane copper-transporting ATPase. Deficient activity of the ATP7A protein results in decreased intestinal absorption of copper, low copper level in serum and defective distribution of copper in tissues. The clinical symptoms are caused by decreased activities of copper-dependent enzymes and include neurodegeneration, connective tissue disorders, arterial changes and hair abnormalities. Without therapy, the disease is fatal in early infancy. Rapid diagnosis of Menkes disease and early start of copper therapy is critical for the effectiveness of treatment. We report a molecular biology-based strategy that allows early diagnosis of copper transport defects and implementation of individual therapies before the full development of pathological symptoms. Low serum copper and decreased activity of copperdependent mitochondrial cytochrome c oxidase in isolated platelets found in three patients indicated a possibility of functional defects in copper-transporting proteins, especially in the ATPA7 protein, a copper- transporting P-type ATPase. Rapid mutational screening of the ATP7A gene using high-resolution melting analysis of DNA indicated presence of mutations in the patients. Molecular investigation for mutations in the ATP7A gene revealed three nonsense mutations: c.2170C>T (p.Gln724Ter); c.3745G>T (p.Glu1249Ter); and c.3862C>T (p.Gln1288Ter). The mutation c.3745G>T (p.Glu1249Ter) has not been identified previously. Molecular analysis of the ATOX1 gene as a possible modulating factor of Menkes disease did not reveal presence of pathogenic mutations. Molecular diagnostics allowed early onset of individual therapies, adequate genetic counselling and prenatal diagnosis in the affected families.

The impact of RABL2B gene (rs144944885) on human male infertility in patients with oligoasthenoteratozoospermia and immotile short tail sperm defects.

PubMed

Hosseini, Seyedeh Hanieh; Sadighi Gilani, Mohammad Ali; Meybodi, Anahita Mohseni; Sabbaghian, Marjan

2017-04-01

Male infertility is a multifactorial disorder with impressively genetic basis; besides, sperm abnormalities are the cause of numerous cases of male infertility. In this study, we evaluated the genetic variants in exons 4 and 5 and their intron-exon boundaries in RABL2B gene in infertile men with oligoasthenoteratozoospermia (OAT) and immotile short tail sperm (ISTS) defects to define if there is any association between these variants and human male infertility. To this purpose, DNA was extracted from peripheral blood and after PCR reaction and sequencing, the results of sequenced segments were analyzed. In the present study, 30 infertile men with ISTS defect and 30 oligoasthenoteratozoospermic infertile men were recruited. All men were of Iranian origin and it took 3 years to collect patient's samples with ISTS defect. As a result, the 50776482 delC intronic variant (rs144944885) was identified in five patients with oligoasthenoteratozoospermia defect and one patient with ISTS defect in heterozygote form. This variant was not identified in controls. The allelic frequency of the 50776482 delC variant was significantly statistically higher in oligoasthenoteratozoospermic infertile men (p < 0.05). Bioinformatics studies suggested that the 50776482 delC allele would modify the splicing of RABL2B pre-mRNA. In addition, we identified a new genetic variant in RABL2B gene. According to the present study, 50776482 delC allele in the RABL2B gene could be a risk factor in Iranian infertile men with oligoasthenoteratozoospermia defect, but more genetic studies are required to understand the accurate role of this variant in pathogenesis of human male infertility.

Glutaric acidemia type II: gene structure and mutations of the electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO) gene.

PubMed

Goodman, Stephen I; Binard, Robert J; Woontner, Michael R; Frerman, Frank E

2002-01-01

Glutaric acidemia type II is a human inborn error of metabolism which can be due to defects in either subunit of electron transfer flavoprotein (ETF) or in ETF:ubiquinone oxidoreductase (ETF:QO), but few disease-causing mutations have been described. The ETF:QO gene is located on 4q33, and contains 13 exons. Primers to amplify these exons are presented, together with mutations identified by molecular analysis of 20 ETF:QO-deficient patients. Twenty-one different disease-causing mutations were identified on 36 of the 40 chromosomes.

DNA replication machinery is required for development in Drosophila.

PubMed

Kohzaki, Hidetsugu; Asano, Maki; Murakami, Yota

2018-01-01

 In Drosophila , some factors involved in chromosome replication seem to be involved in gene amplification and endoreplication, which are actively utilized in particular tissue development, but direct evidence has not been shown. Therefore, we examined the effect of depletion of replication factors on these processes. First, we confirmed RNAi knockdown can be used for the depletion of replication factors by comparing the phenotypes of RNAi knockdown and deletion or point mutants of the components of DNA licensing factor, MCM2, MCM4 and Cdt1. Next, we found that tissue-specific RNAi knockdown of replication factors caused tissue-specific defects, probably due to defects in DNA replication. In particular, we found that depletion inhibited gene amplification of the chorion gene in follicle cells and endoreplication in salivary glands, showing that chromosomal DNA replication factors are required for these processes. Finally, using RNAi, we screened the genes for chromosomal DNA replication that affected tissue development. Interestingly, wing specific knockdown of Mcm10 induced wing formation defects. These results suggest that some components of chromosomal replication machinery are directly involved in tissue development.

A somatic T15091C mutation in the Cytb gene of mouse mitochondrial DNA dominantly induces respiration defects.

PubMed

Hayashi, Chisato; Takibuchi, Gaku; Shimizu, Akinori; Mito, Takayuki; Ishikawa, Kaori; Nakada, Kazuto; Hayashi, Jun-Ichi

2015-08-07

Our previous studies provided evidence that mammalian mitochondrial DNA (mtDNA) mutations that cause mitochondrial respiration defects behave in a recessive manner, because the induction of respiration defects could be prevented with the help of a small proportion (10%-20%) of mtDNA without the mutations. However, subsequent studies found the induction of respiration defects by the accelerated accumulation of a small proportion of mtDNA with various somatic mutations, indicating the presence of mtDNA mutations that behave in a dominant manner. Here, to provide the evidence for the presence of dominant mutations in mtDNA, we used mouse lung carcinoma P29 cells and examined whether some mtDNA molecules possess somatic mutations that dominantly induce respiration defects. Cloning and sequence analysis of 40-48 mtDNA molecules from P29 cells was carried out to screen for somatic mutations in protein-coding genes, because mutations in these genes could dominantly regulate respiration defects by formation of abnormal polypeptides. We found 108 missense mutations existing in one or more of 40-48 mtDNA molecules. Of these missense mutations, a T15091C mutation in the Cytb gene was expected to be pathogenic due to the presence of its orthologous mutation in mtDNA from a patient with cardiomyopathy. After isolation of many subclones from parental P29 cells, we obtained subclones with various proportions of T15091C mtDNA, and showed that the respiration defects were induced in a subclone with only 49% T15091C mtDNA. Because the induction of respiration defects could not be prevented with the help of the remaining 51% mtDNA without the T15091C mutation, the results indicate that the T15091C mutation in mtDNA dominantly induced the respiration defects. Copyright © 2015 Elsevier Inc. All rights reserved.

The Complex Genetic Basis of Congenital Heart Defects

PubMed Central

Akhirome, Ehiole; Walton, Nephi A.; Nogee, Julie M.; Jay, Patrick Y.

2017-01-01

Twenty years ago, chromosomal abnormalities were the only identifiable genetic causes of a small fraction of congenital heart defects (CHD). Today, a de novo or inherited genetic abnormality can be identified as pathogenic in one-third of cases. We refer to them here as monogenic causes, insofar as the genetic abnormality has a readily detectable, large effect. What explains the other two-thirds? This review considers a complex genetic basis. That is, a combination of genetic mutations or variants that individually may have little or no detectable effect contribute to the pathogenesis of a heart defect. Genes in the embryo that act directly in cardiac developmental pathways have received the most attention, but genes in the mother that establish the gestational milieu via pathways related to metabolism and aging also have an effect. A growing body of evidence highlights the pathogenic significance of genetic interactions in the embryo and maternal effects that have a genetic basis. The investigation of CHD as guided by a complex genetic model could help estimate risk more precisely and logically lead to a means of prevention. PMID:28381817

PHRED-1 is a divergent neurexin-1 homolog that organizes muscle fibers and patterns organs during regeneration.

PubMed

Adler, Carolyn E; Sánchez Alvarado, Alejandro

2017-07-01

Regeneration of body parts requires the replacement of multiple cell types. To dissect this complex process, we utilized planarian flatworms that are capable of regenerating any tissue after amputation. An RNAi screen for genes involved in regeneration of the pharynx identified a novel gene, Pharynx regeneration defective-1 (PHRED-1) as essential for normal pharynx regeneration. PHRED-1 is a predicted transmembrane protein containing EGF, Laminin G, and WD40 domains, is expressed in muscle, and has predicted homologs restricted to other lophotrochozoan species. Knockdown of PHRED-1 causes abnormal regeneration of muscle fibers in both the pharynx and body wall muscle. In addition to defects in muscle regeneration, knockdown of PHRED-1 or the bHLH transcription factor MyoD also causes defects in muscle and intestinal regeneration. Together, our data demonstrate that muscle plays a key role in restoring the structural integrity of closely associated organs, and in planarians it may form a scaffold that facilitates normal intestinal branching. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

The retinal phenotype of Usher syndrome: pathophysiological insights from animal models.

PubMed

El-Amraoui, Aziz; Petit, Christine

2014-03-01

The Usher syndrome (USH) is the most prevalent cause of inherited deaf-blindness. Three clinical subtypes, USH1-3, have been defined, and ten USH genes identified. The hearing impairment due to USH gene defects has been shown to result from improper organisation of the hair bundle, the sound receptive structure of sensory hair cells. In contrast, the cellular basis of the visual defect is less well understood as this phenotype is absent in almost all the USH mouse models that faithfully mimic the human hearing impairment. Structural and molecular interspecies discrepancies regarding photoreceptor calyceal processes and the association with the distribution of USH1 proteins have recently been unravelled, and have led to the conclusion that a defect in the USH1 protein complex-mediated connection between the photoreceptor outer segment and the surrounding calyceal processes (in both rods and cones), and the inner segment (in rods only), probably causes the USH1 retinal dystrophy in humans. Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Engineered chromosome-based genetic mapping establishes a 3.7 Mb critical genomic region for Down syndrome-associated heart defects in mice.

PubMed

Liu, Chunhong; Morishima, Masae; Jiang, Xiaoling; Yu, Tao; Meng, Kai; Ray, Debjit; Pao, Annie; Ye, Ping; Parmacek, Michael S; Yu, Y Eugene

2014-06-01

Trisomy 21 (Down syndrome, DS) is the most common human genetic anomaly associated with heart defects. Based on evolutionary conservation, DS-associated heart defects have been modeled in mice. By generating and analyzing mouse mutants carrying different genomic rearrangements in human chromosome 21 (Hsa21) syntenic regions, we found the triplication of the Tiam1-Kcnj6 region on mouse chromosome 16 (Mmu16) resulted in DS-related cardiovascular abnormalities. In this study, we developed two tandem duplications spanning the Tiam1-Kcnj6 genomic region on Mmu16 using recombinase-mediated genome engineering, Dp(16)3Yey and Dp(16)4Yey, spanning the 2.1 Mb Tiam1-Il10rb and 3.7 Mb Ifnar1-Kcnj6 regions, respectively. We found that Dp(16)4Yey/+, but not Dp(16)3Yey/+, led to heart defects, suggesting the triplication of the Ifnar1-Kcnj6 region is sufficient to cause DS-associated heart defects. Our transcriptional analysis of Dp(16)4Yey/+ embryos showed that the Hsa21 gene orthologs located within the duplicated interval were expressed at the elevated levels, reflecting the consequences of the gene dosage alterations. Therefore, we have identified a 3.7 Mb genomic region, the smallest critical genomic region, for DS-associated heart defects, and our results should set the stage for the final step to establish the identities of the causal gene(s), whose elevated expression(s) directly underlie this major DS phenotype.

A mutation in the Norrie disease gene (NDP) associated with X-linked familial exudative vitreoretinopathy.

PubMed

Chen, Z Y; Battinelli, E M; Fielder, A; Bundey, S; Sims, K; Breakefield, X O; Craig, I W

1993-10-01

Familial exudative vitreoretinopathy (FEVR) is a hereditary disorder characterized by an abnormality of the peripheral retina. Both autosomal dominant (adFEVR) and X-linked (XLFEVR) forms have been described, but the biochemical defect(s) underlying the symptoms are unknown. Molecular analysis of the Norrie gene locus (NDP) in a four generation FEVR family (shown previously to exhibit linkage to the X-chromosome markers DXS228 and MAOA (Xp11.4-p11.3)) reveals a missense mutation in the highly conserved region of the NDP gene, which caused a neutral amino acid substitution (Leu124Phe), was detected in all of the affected males, but not in the unaffected family members, nor in normal controls. The observations suggest that phenotypes of both XLFEVR and Norrie disease can result from mutations in the same gene.

Targeted Resequencing of 29 Candidate Genes and Mouse Expression Studies Implicate ZIC3 and FOXF1 in Human VATER/VACTERL Association.

PubMed

Hilger, Alina C; Halbritter, Jan; Pennimpede, Tracie; van der Ven, Amelie; Sarma, Georgia; Braun, Daniela A; Porath, Jonathan D; Kohl, Stefan; Hwang, Daw-Yang; Dworschak, Gabriel C; Hermann, Bernhard G; Pavlova, Anna; El-Maarri, Osman; Nöthen, Markus M; Ludwig, Michael; Reutter, Heiko; Hildebrandt, Friedhelm

2015-12-01

The VATER/VACTERL association describes the combination of congenital anomalies including vertebral defects, anorectal malformations, cardiac defects, tracheoesophageal fistula with or without esophageal atresia, renal malformations, and limb defects. As mutations in ciliary genes were observed in diseases related to VATER/VACTERL, we performed targeted resequencing of 25 ciliary candidate genes as well as disease-associated genes (FOXF1, HOXD13, PTEN, ZIC3) in 123 patients with VATER/VACTERL or VATER/VACTERL-like phenotype. We detected no biallelic mutation in any of the 25 ciliary candidate genes; however, identified an identical, probably disease-causing ZIC3 missense mutation (p.Gly17Cys) in four patients and a FOXF1 de novo mutation (p.Gly220Cys) in a further patient. In situ hybridization analyses in mouse embryos between E9.5 and E14.5 revealed Zic3 expression in limb and prevertebral structures, and Foxf1 expression in esophageal, tracheal, vertebral, anal, and genital tubercle tissues, hence VATER/VACTERL organ systems. These data provide strong evidence that mutations in ZIC3 or FOXF1 contribute to VATER/VACTERL. © 2015 WILEY PERIODICALS, INC.

POB3 is required for both transcription and replication in the yeast Saccharomyces cerevisiae.

PubMed Central

Schlesinger, M B; Formosa, T

2000-01-01

Spt16 and Pob3 form stable heterodimers in Saccharomyces cerevisiae, and homologous proteins have also been purified as complexes from diverse eukaryotes. This conserved factor has been implicated in both transcription and replication and may affect both by altering the characteristics of chromatin. Here we describe the isolation and properties of a set of pob3 mutants and confirm that they have defects in both replication and transcription. Mutation of POB3 caused the Spt(-) phenotype, spt16 and pob3 alleles displayed severe synthetic defects, and elevated levels of Pob3 suppressed some spt16 phenotypes. These results are consistent with previous reports that Spt16 and Pob3 act in a complex that modulates transcription. Additional genetic interactions were observed between pob3 mutations and the genes encoding several DNA replication factors, including POL1, CTF4, DNA2, and CHL12. pob3 alleles caused sensitivity to the ribonucleotide reductase inhibitor hydroxyurea, indicating a defect in a process requiring rapid dNTP synthesis. Mutation of the S phase checkpoint gene MEC1 caused pob3 mutants to lose viability rapidly under restrictive conditions, revealing defects in a process monitored by Mec1. Direct examination of DNA contents by flow cytometry showed that S phase onset and progression were delayed when POB3 was mutated. We conclude that Pob3 is required for normal replication as well as for transcription. PMID:10924459

Defects in the cappuccino (cno) gene on mouse chromosome 5 and human 4p cause Hermansky-Pudlak syndrome by an AP-3-independent mechanism.

PubMed

Gwynn, B; Ciciotte, S L; Hunter, S J; Washburn, L L; Smith, R S; Andersen, S G; Swank, R T; Dell'Angelica, E C; Bonifacino, J S; Eicher, E M; Peters, L L

2000-12-15

Defects in a triad of organelles (melanosomes, platelet granules, and lysosomes) result in albinism, prolonged bleeding, and lysosome abnormalities in Hermansky-Pudlak syndrome (HPS). Defects in HPS1, a protein of unknown function, and in components of the AP-3 complex cause some, but not all, cases of HPS in humans. There have been 15 inherited models of HPS described in the mouse, underscoring its marked genetic heterogeneity. Here we characterize a new spontaneous mutation in the mouse, cappuccino (cno), that maps to mouse chromosome 5 in a region conserved with human 4p15-p16. Melanosomes of cno/cno mice are immature and dramatically decreased in number in the eye and skin, resulting in severe oculocutaneous albinism. Platelet dense body contents (adenosine triphosphate, serotonin) are markedly deficient, leading to defective aggregation and prolonged bleeding. Lysosomal enzyme concentrations are significantly elevated in the kidney and liver. Genetic, immunofluorescence microscopy, and lysosomal protein trafficking studies indicate that the AP-3 complex is intact in cno/cno mice. It was concluded that the cappuccino gene encodes a product involved in an AP-3-independent mechanism critical to the biogenesis of lysosome-related organelles. (Blood. 2000;96:4227-4235)

Nephronophthisis: Disease Mechanisms of a Ciliopathy

PubMed Central

Hildebrandt, Friedhelm; Attanasio, Massimo; Otto, Edgar

2009-01-01

Nephronophthisis (NPHP), a recessive cystic kidney disease, is the most frequent genetic cause of end-stage kidney disease in children and young adults. Positional cloning of nine genes (NPHP1-9) and functional characterization of their encoded proteins (nephrocystins) has contributed to a unifying theory that defines cystic kidney diseases as “ciliopathies”. The theory is based on the finding that all proteins mutated in cystic kidney diseases of humans or animal models are expressed in primary cilia or centrosomes of renal epithelial cells. Primary cilia are sensory organelles that connect mechanosensory, visual, and other stimuli to mechanisms of epithelial cell polarity and cell cycle control. Mutations in NPHP genes cause defects in signaling mechanisms that involve the non-canonical Wnt signaling pathway and the sonic hedgehog signaling pathway, resulting in defects of planar cell polarity and tissue maintenance. The ciliary theory explains the multiple organ involvement in NPHP, which includes retinal degeneration, cerebellar hypoplasia, liver fibrosis, situs inversus, and mental retardation. Positional cloning of dozens of unknown genes that cause NPHP will elucidate further signaling mechanisms involved. Nephrocystins are highly conserved in evolution, thus allowing the use of animal models to develop future therapeutic approaches. PMID:19118152

Genetics Home Reference: autosomal dominant leukodystrophy with autonomic disease

MedlinePlus

... gene provides instructions for making the lamin B1 protein. Lamin B1 is an essential scaffolding ... VE, Casaccia P, Padiath QS. Defects of Lipid Synthesis Are Linked to the Age-Dependent Demyelination Caused ...

Two distinct roles of the yorkie/yap gene during homeostasis in the planarian Dugesia japonica.

PubMed

Hwang, Byulnim; An, Yang; Agata, Kiyokazu; Umesono, Yoshihiko

2015-04-01

Adult planarians possess somatic pluripotent stem cells called neoblasts that give rise to all missing cell types during regeneration and homeostasis. Recent studies revealed that the Yorkie (Yki)/Yes-associated protein (YAP) transcriptional coactivator family plays an important role in the regulation of tissue growth during development and regeneration, and therefore we investigated the role of a planarian yki-related gene (termed Djyki) during regeneration and homeostasis of the freshwater planarian Dugesia japonica. We found that knockdown of the function of Djyki by RNA interference (RNAi) downregulated neoblast proliferation and caused regeneration defects after amputation. In addition, Djyki RNAi caused edema during homeostasis. These seemingly distinct defects induced by Djyki RNAi were rescued by simultaneous RNAi of a planarian mats-related gene (termed Djmats), suggesting an important role of Djmats in the negative regulation of Djyki, in accordance with the conservation of the functional relationship of these two genes during the course of evolution. Interestingly, Djyki RNAi did not prevent normal protonephridial structure, suggesting that Djyki RNAi induced the edema phenotype without affecting the excretory system. Further analyses revealed that increased expression of the D. japonica gene DjaquaporinA (DjaqpA), which belongs to a large gene family that encodes a water channel protein for the regulation of transcellular water flow, promoted the induction of edema, but not defects in neoblast dynamics, in Djyki(RNAi) animals. Thus, we conclude that Djyki plays two distinct roles in the regulation of active proliferation of stem cells and in osmotic water transport across the body surface in D. japonica. © 2015 The Authors Development, Growth & Differentiation published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Society of Developmental Biologists.

Introduction to the special issue on Social Darwinism.

PubMed

Albee, G W

1996-09-01

A brief history is provided of interventions with people with emotional disorders since the 1950s. A shortage of therapists is inescapable and even successful treatment does not change incidence. But the individual defect model supports the conservative view that causes are to be found inside people, rather than in social injustice. People who are defective are to be treated as part of the medical model that is extended to cover social problems. This view is an obvious extension of Social Darwinism that has long attributed success and failure to bad genes and good genes rather than to advantaged and disadvantaged social-economic environments.

Exome sequencing reveals riboflavin transporter mutations as a cause of motor neuron disease.

PubMed

Johnson, Janel O; Gibbs, J Raphael; Megarbane, Andre; Urtizberea, J Andoni; Hernandez, Dena G; Foley, A Reghan; Arepalli, Sampath; Pandraud, Amelie; Simón-Sánchez, Javier; Clayton, Peter; Reilly, Mary M; Muntoni, Francesco; Abramzon, Yevgeniya; Houlden, Henry; Singleton, Andrew B

2012-09-01

Brown-Vialetto-Van Laere syndrome was first described in 1894 as a rare neurodegenerative disorder characterized by progressive sensorineural deafness in combination with childhood amyotrophic lateral sclerosis. Mutations in the gene, SLC52A3 (formerly C20orf54), one of three known riboflavin transporter genes, have recently been shown to underlie a number of severe cases of Brown-Vialetto-Van Laere syndrome; however, cases and families with this disease exist that do not appear to be caused by SLC52A3 mutations. We used a combination of linkage and exome sequencing to identify the disease causing mutation in an extended Lebanese Brown-Vialetto-Van Laere kindred, whose affected members were negative for SLC52A3 mutations. We identified a novel mutation in a second member of the riboflavin transporter gene family (gene symbol: SLC52A2) as the cause of disease in this family. The same mutation was identified in one additional subject, from 44 screened. Within this group of 44 patients, we also identified two additional cases with SLC52A3 mutations, but none with mutations in the remaining member of this gene family, SLC52A1. We believe this strongly supports the notion that defective riboflavin transport plays an important role in Brown-Vialetto-Van Laere syndrome. Initial work has indicated that patients with SLC52A3 defects respond to riboflavin treatment clinically and biochemically. Clearly, this makes an excellent candidate therapy for the SLC52A2 mutation-positive patients identified here. Initial riboflavin treatment of one of these patients shows promising results.

Exome sequencing reveals riboflavin transporter mutations as a cause of motor neuron disease

PubMed Central

Johnson, Janel O.; Gibbs, J. Raphael; Megarbane, Andre; Urtizberea, J. Andoni; Hernandez, Dena G.; Foley, A. Reghan; Arepalli, Sampath; Pandraud, Amelie; Simón-Sánchez, Javier; Clayton, Peter; Reilly, Mary M.; Muntoni, Francesco; Abramzon, Yevgeniya; Houlden, Henry

2012-01-01

Brown–Vialetto–Van Laere syndrome was first described in 1894 as a rare neurodegenerative disorder characterized by progressive sensorineural deafness in combination with childhood amyotrophic lateral sclerosis. Mutations in the gene, SLC52A3 (formerly C20orf54), one of three known riboflavin transporter genes, have recently been shown to underlie a number of severe cases of Brown–Vialetto–Van Laere syndrome; however, cases and families with this disease exist that do not appear to be caused by SLC52A3 mutations. We used a combination of linkage and exome sequencing to identify the disease causing mutation in an extended Lebanese Brown–Vialetto–Van Laere kindred, whose affected members were negative for SLC52A3 mutations. We identified a novel mutation in a second member of the riboflavin transporter gene family (gene symbol: SLC52A2) as the cause of disease in this family. The same mutation was identified in one additional subject, from 44 screened. Within this group of 44 patients, we also identified two additional cases with SLC52A3 mutations, but none with mutations in the remaining member of this gene family, SLC52A1. We believe this strongly supports the notion that defective riboflavin transport plays an important role in Brown–Vialetto–Van Laere syndrome. Initial work has indicated that patients with SLC52A3 defects respond to riboflavin treatment clinically and biochemically. Clearly, this makes an excellent candidate therapy for the SLC52A2 mutation-positive patients identified here. Initial riboflavin treatment of one of these patients shows promising results. PMID:22740598

Temporal requirements of the fragile X mental retardation protein in the regulation of synaptic structure.

PubMed

Gatto, Cheryl L; Broadie, Kendal

2008-08-01

Fragile X syndrome (FraX), caused by the loss-of-function of one gene (FMR1), is the most common inherited form of both mental retardation and autism spectrum disorders. The FMR1 product (FMRP) is an mRNA-binding translation regulator that mediates activity-dependent control of synaptic structure and function. To develop any FraX intervention strategy, it is essential to define when and where FMRP loss causes the manifestation of synaptic defects, and whether the reintroduction of FMRP can restore normal synapse properties. In the Drosophila FraX model, dFMRP loss causes neuromuscular junction (NMJ) synapse over-elaboration (overgrowth, overbranching, excess synaptic boutons), accumulation of development-arrested satellite boutons, and altered neurotransmission. We used the Gene-Switch method to conditionally drive dFMRP expression to define the spatiotemporal requirements in synaptic mechanisms. Constitutive induction of targeted neuronal dFMRP at wild-type levels rescues all synaptic architectural defects in Drosophila Fmr1 (dfmr1)-null mutants, demonstrating a presynaptic requirement for synapse structuring. By contrast, presynaptic dFMRP expression does not ameliorate functional neurotransmission defects, indicating a postsynaptic dFMRP requirement. Strikingly, targeted early induction of dFMRP effects nearly complete rescue of synaptic structure defects, showing a primarily early-development role. In addition, acute dFMRP expression at maturity partially alleviates dfmr1-null defects, although rescue is not as complete as either early or constitutive dFMRP expression, showing a modest capacity for late-stage structural plasticity. We conclude that dFMRP predominantly acts early in synaptogenesis to modulate architecture, but that late dFMRP introduction at maturity can weakly compensate for early absence of dFMRP function.

Dosage Mutator Genes in Saccharomyces cerevisiae: A Novel Mutator Mode-of-Action of the Mph1 DNA Helicase.

PubMed

Ang, J Sidney; Duffy, Supipi; Segovia, Romulo; Stirling, Peter C; Hieter, Philip

2016-11-01

Mutations that cause genome instability are considered important predisposing events that contribute to initiation and progression of cancer. Genome instability arises either due to defects in genes that cause an increased mutation rate (mutator phenotype), or defects in genes that cause chromosome instability (CIN). To extend the catalog of genome instability genes, we systematically explored the effects of gene overexpression on mutation rate, using a forward-mutation screen in budding yeast. We screened ∼5100 plasmids, each overexpressing a unique single gene, and characterized the five strongest mutators, MPH1 (mutator phenotype 1), RRM3, UBP12, PIF1, and DNA2 We show that, for MPH1, the yeast homolog of Fanconi Anemia complementation group M (FANCM), the overexpression mutator phenotype is distinct from that of mph1Δ. Moreover, while four of our top hits encode DNA helicases, the overexpression of 48 other DNA helicases did not cause a mutator phenotype, suggesting this is not a general property of helicases. For Mph1 overexpression, helicase activity was not required for the mutator phenotype; in contrast Mph1 DEAH-box function was required for hypermutation. Mutagenesis by MPH1 overexpression was independent of translesion synthesis (TLS), but was suppressed by overexpression of RAD27, a conserved flap endonuclease. We propose that binding of DNA flap structures by excess Mph1 may block Rad27 action, creating a mutator phenotype that phenocopies rad27Δ. We believe this represents a novel mutator mode-of-action and opens up new prospects to understand how upregulation of DNA repair proteins may contribute to mutagenesis. Copyright © 2016 by the Genetics Society of America.

Treatment of autistic spectrum disorder with insulin-like growth factors.

PubMed

Riikonen, Raili

2016-11-01

There are no treatments for the core symptoms of autistic spectrum disorder (ASD), but there is now more knowledge on emerging mechanisms and on mechanism-based therapies. In autism there are altered synapses: genes affected are commonly related to synaptic and immune function. Dysregulation of activity-dependent signaling networks may have a key role the etiology of autism. There is an over-activation of IGF-AKT-mTor in autism spectrum disorders. Morphological and electro-physiological defects of the cerebellum are linked to system-wide ASD-like behavior defects. The molecular basis for a cerebellar contribution has been demonstrated in a mouse model. These have led to a potential mechanism-based use of drug targets and mouse models. Neurotrophic factors are potential candidates for the treatment. Insulin-like growth factor-1 (IGF-1) is altered in autism. It reduces neuro-inflammation: by causing changes of cytokines such as IL-6 and microglial function. IGF-1 reduces the defects in the synapse. It alleviates NMDA-induced neurotoxicity via the IGF-AKT-mTor pathway in microglia. IGF-1 may rescue function in Rett syndrome and ASD caused by changes of the SCHANK3 gene. There are recently pilot studies of the treatment of Rett syndrome and of SCHANK3 gene deficiency syndromes. The FDA has granted Orphan drug designations for Fragile X syndrome, SCHANK3 gene deficiency syndrome and Rett syndrome. Copyright © 2016 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

VID22 is required for transcriptional activation of the PSD2 gene in the yeast Saccharomyces cerevisiae.

PubMed

Miyata, Non; Miyoshi, Takuya; Yamaguchi, Takanori; Nakazono, Toshimitsu; Tani, Motohiro; Kuge, Osamu

2015-12-15

Phosphatidylethanolamine (PE) in the yeast Saccharomyces cerevisiae is synthesized through decarboxylation of phosphatidylserine (PS), catalysed by PS decarboxylase 1 (Psd1p) and 2 (Psd2p) and the cytidine 5'-diphosphate (CDP)-ethanolamine (CDP-Etn) pathway. PSD1 null (psd1Δ) and PSD2 null (psd2Δ) mutants are viable in a synthetic minimal medium, but a psd1Δ psd2Δ double mutant exhibits Etn auxotrophy, which is incorporated into PE through the CDP-Etn pathway. We have previously shown that psd1Δ is synthetic lethal with deletion of VID22 (vid22Δ) [Kuroda et al. (2011) Mol. Microbiol. 80: , 248-265]. In the present study, we found that vid22Δ mutant exhibits Etn auxotrophy under PSD1-depressed conditions. Deletion of VID22 in wild-type and PSD1-depressed cells caused partial defects in PE formation through decarboxylation of PS. The enzyme activity of PS decarboxylase in an extract of vid22Δ cells was ∼70% of that in wild-type cells and similar to that in psd2Δ cells and the PS decarboxylase activity remaining in the PSD1-depressed cells became almost negligible with deletion of VID22. Thus, the vid22Δ mutation was suggested to cause a defect in the Psd2p activity. Furthermore, vid22Δ cells were shown to be defective in expression of the PSD2 gene tagged with 6×HA, the defect being ameliorated by replacement of the native promoter of the PSD2 gene with a CYC1 promoter. In addition, an α-galactosidase reporter assay revealed that the activity of the promoter of the PSD2 gene in vid22Δ cells was ∼5% of that in wild-type cells. These results showed that VID22 is required for transcriptional activation of the PSD2 gene. © 2015 Authors; published by Portland Press Limited.

Deletion of Ku80 causes early aging independent of chronic inflammation and Rag-1-induced DSBs.

PubMed

Holcomb, Valerie B; Vogel, Hannes; Hasty, Paul

2007-01-01

Animal models of premature aging are often defective for DNA repair. Ku80-mutant mice are disabled for nonhomologous end joining; a pathway that repairs both spontaneous DNA double-strand breaks (DSBs) and induced DNA DSBs generated by the action of a complex composed of Rag-1 and Rag-2 (Rag). Rag is essential for inducing DSBs important for assembling V(D)J segments of antigen receptor genes that are required for lymphocyte development. Thus, deletion of either Rag-1 or Ku80 causes severe combined immunodeficiency (scid) leading to chronic inflammation. In addition, Rag-1 induces breaks at non-B DNA structures. Previously we reported Ku80-mutant mice undergo premature aging, yet we do not know the root cause of this phenotype. Early aging may be caused by either defective repair of spontaneous DNA damage, defective repair of Rag-1-induced breaks or chronic inflammation caused by scid. To address this issue, we analyzed aging in control and Ku80-mutant mice deleted for Rag-1 such that both cohorts are scid and suffer from chronic inflammation. We make two observations: (1) chronic inflammation does not cause premature aging in these mice and (2) Ku80-mutant mice exhibit early aging independent of Rag-1. Therefore, this study supports defective repair of spontaneous DNA damage as the root cause of early aging in Ku80-mutant mice.

The Microphthalmia Transcription Factor (Mitf) Controls Expression of the Ocular Albinism Type 1 Gene: Link between Melanin Synthesis and Melanosome Biogenesis

PubMed Central

Vetrini, Francesco; Auricchio, Alberto; Du, Jinyan; Angeletti, Barbara; Fisher, David E.; Ballabio, Andrea; Marigo, Valeria

2004-01-01

Melanogenesis is the process that regulates skin and eye pigmentation. Albinism, a genetic disease causing pigmentation defects and visual disorders, is caused by mutations in genes controlling either melanin synthesis or melanosome biogenesis. Here we show that a common transcriptional control regulates both of these processes. We performed an analysis of the regulatory region of Oa1, the murine homolog of the gene that is mutated in the X-linked form of ocular albinism, as Oa1's function affects melanosome biogenesis. We demonstrated that Oa1 is a target of Mitf and that this regulatory mechanism is conserved in the human gene. Tissue-specific control of Oa1 transcription lies within a region of 617 bp that contains the E-box bound by Mitf. Finally, we took advantage of a virus-based system to assess tissue specificity in vivo. To this end, a small fragment of the Oa1 promoter was cloned in front of a reporter gene in an adeno-associated virus. After we injected this virus into the subretinal space, we observed reporter gene expression specifically in the retinal pigment epithelium, confirming the cell-specific expression of the Oa1 promoter in the eye. The results obtained with this viral system are a preamble to the development of new gene delivery approaches for the treatment of retinal pigment epithelium defects. PMID:15254223

Defective B cell tolerance in adenosine deaminase deficiency is corrected by gene therapy

PubMed Central

Sauer, Aisha V.; Morbach, Henner; Brigida, Immacolata; Ng, Yen-Shing; Aiuti, Alessandro; Meffre, Eric

2012-01-01

Adenosine deaminase (ADA) gene defects are among the most common causes of SCID. Restoration of purine metabolism and immune functions can be achieved by enzyme replacement therapy, or more effectively by bone marrow transplant or HSC gene therapy (HSC-GT). However, autoimmune complications and autoantibody production, including anti-nuclear antibodies (ANAs), frequently occur in ADA-SCID patients after treatment. To assess whether ADA deficiency affects the establishment of B cell tolerance, we tested the reactivity of recombinant antibodies isolated from single B cells of ADA-SCID patients before and after HSC-GT. We found that before HSC-GT, new emigrant/transitional and mature naive B cells from ADA-SCID patients contained more autoreactive and ANA-expressing clones, indicative of defective central and peripheral B cell tolerance checkpoints. We further observed impaired B cell receptor (BCR) and TLR functions in B cells after ADA inhibition, which may underlie the defects in B cell tolerance. Strikingly, after HSC-GT, ADA-SCID patients displayed quasi-normal early B cell tolerance checkpoints, as evidenced by restored removal of developing autoreactive and ANA-expressing B cells. Hence, ADA plays an essential role in controlling autoreactive B cell counterselection by regulating BCR and TLR functions. PMID:22622038

Rapid screening for nuclear genes mutations in isolated respiratory chain complex I defects.

PubMed

Pagniez-Mammeri, Hélène; Lombes, Anne; Brivet, Michèle; Ogier-de Baulny, Hélène; Landrieu, Pierre; Legrand, Alain; Slama, Abdelhamid

2009-04-01

Complex I or reduced nicotinamide adenine dinucleotide (NADH): ubiquinone oxydoreductase deficiency is the most common cause of respiratory chain defects. Molecular bases of complex I deficiencies are rarely identified because of the dual genetic origin of this multi-enzymatic complex (nuclear DNA and mitochondrial DNA) and the lack of phenotype-genotype correlation. We used a rapid method to screen patients with isolated complex I deficiencies for nuclear genes mutations by Surveyor nuclease digestion of cDNAs. Eight complex I nuclear genes, among the most frequently mutated (NDUFS1, NDUFS2, NDUFS3, NDUFS4, NDUFS7, NDUFS8, NDUFV1 and NDUFV2), were studied in 22 cDNA fragments spanning their coding sequences in 8 patients with a biochemically proved complex I deficiency. Single nucleotide polymorphisms and missense mutations were detected in 18.7% of the cDNA fragments by Surveyor nuclease treatment. Molecular defects were detected in 3 patients. Surveyor nuclease screening is a reliable method for genotyping nuclear complex I deficiencies, easy to interpret, and limits the number of sequence reactions. Its use will enhance the possibility of prenatal diagnosis and help us for a better understanding of complex I molecular defects.

Integrated sequence analysis pipeline provides one-stop solution for identifying disease-causing mutations.

PubMed

Hu, Hao; Wienker, Thomas F; Musante, Luciana; Kalscheuer, Vera M; Kahrizi, Kimia; Najmabadi, Hossein; Ropers, H Hilger

2014-12-01

Next-generation sequencing has greatly accelerated the search for disease-causing defects, but even for experts the data analysis can be a major challenge. To facilitate the data processing in a clinical setting, we have developed a novel medical resequencing analysis pipeline (MERAP). MERAP assesses the quality of sequencing, and has optimized capacity for calling variants, including single-nucleotide variants, insertions and deletions, copy-number variation, and other structural variants. MERAP identifies polymorphic and known causal variants by filtering against public domain databases, and flags nonsynonymous and splice-site changes. MERAP uses a logistic model to estimate the causal likelihood of a given missense variant. MERAP considers the relevant information such as phenotype and interaction with known disease-causing genes. MERAP compares favorably with GATK, one of the widely used tools, because of its higher sensitivity for detecting indels, its easy installation, and its economical use of computational resources. Upon testing more than 1,200 individuals with mutations in known and novel disease genes, MERAP proved highly reliable, as illustrated here for five families with disease-causing variants. We believe that the clinical implementation of MERAP will expedite the diagnostic process of many disease-causing defects. © 2014 WILEY PERIODICALS, INC.

Defects in middle ear cavitation cause conductive hearing loss in the Tcof1 mutant mouse.

PubMed

Richter, Carol A; Amin, Susan; Linden, Jennifer; Dixon, Jill; Dixon, Michael J; Tucker, Abigail S

2010-04-15

Conductive hearing loss (CHL) is one of the most common forms of human deafness. Despite this observation, a surprising gap in our understanding of the mechanisms underlying CHL remains, particularly with respect to the molecular mechanisms underlying middle ear development and disease. Treacher Collins syndrome (TCS) is an autosomal dominant disorder of facial development that results from mutations in the gene TCOF1. CHL is a common feature of TCS but the causes of the hearing defect have not been studied. In this study, we have utilized Tcof1 mutant mice to dissect the developmental mechanisms underlying CHL. Our results demonstrate that effective cavitation of the middle ear is intimately linked to growth of the auditory bulla, the neural crest cell-derived structure that encapsulates all middle ear components, and that defects in these processes have a profoundly detrimental effect on hearing. This research provides important insights into a poorly characterized cause of human deafness, and provides the first mouse model for the study of middle ear cavity defects, while also being of direct relevance to a human genetic disorder.

Mutations in PRPF31 Inhibit Pre-mRNA Splicing of Rhodopsin Gene and Cause Apoptosis of Retinal Cells

PubMed Central

Yuan, Liya; Kawada, Mariko; Havlioglu, Necat; Tang, Hao; Wu, Jane Y.

2007-01-01

Mutations in human PRPF31 gene have been identified in patients with autosomal dominant retinitis pigmentosa (adRP). To begin to understand mechanisms by which defects in this general splicing factor cause retinal degeneration, we examined the relationship between PRPF31 and pre-mRNA splicing of photoreceptor-specific genes. We used a specific anti-PRPF31 antibody to immunoprecipitate splicing complexes from retinal cells and identified the transcript of rhodopsin gene (RHO) among RNA species associated with PRPF31-containing complexes. Mutant PRPF31 proteins significantly inhibited pre-mRNA splicing of intron 3 in RHO gene. In primary retinal cell cultures, expression of the mutant PRPF31 proteins reduced rhodopsin expression and caused apoptosis of rhodopsin-positive retinal cells. This primary retinal culture assay provides an in vitro model to study photoreceptor cell death caused by PRPF31 mutations. Our results demonstrate that mutations in PRPF31 gene affect RHO pre-mRNA splicing and reveal a link between PRPF31 and RHO, two major adRP genes. PMID:15659613

Drosophila models of amyotrophic lateral sclerosis with defects in RNA metabolism.

PubMed

Zhang, Ke; Coyne, Alyssa N; Lloyd, Thomas E

2018-05-09

The fruit fly Drosophila Melanogaster has been widely used to study neurodegenerative diseases. The conservation of nervous system biology coupled with the rapid life cycle and powerful genetic tools in the fly have enabled the identification of novel therapeutic targets that have been validated in vertebrate model systems and human patients. A recent example is in the study of the devastating motor neuron degenerative disease amyotrophic lateral sclerosis (ALS). Mutations in genes that regulate RNA metabolism are a major cause of inherited ALS, and functional analysis of these genes in the fly nervous system has shed light on how mutations cause disease. Importantly, unbiased genetic screens have identified key pathways that contribute to ALS pathogenesis such as nucleocytoplasmic transport and stress granule assembly. In this review, we will discuss the utilization of Drosophila models of ALS with defects in RNA metabolism. Copyright © 2018 Elsevier B.V. All rights reserved.

A novel heterozygous SOX2 mutation causing anophthalmia/microphthalmia with genital anomalies.

PubMed

Pedace, Lucia; Castori, Marco; Binni, Francesco; Pingi, Alberto; Grammatico, Barbara; Scommegna, Salvatore; Majore, Silvia; Grammatico, Paola

2009-01-01

Anophthalmia/microphthalmia is a rare developmental craniofacial defect, which recognizes a wide range of causes, including chromosomal abnormalities, single-gene mutations as well as environmental factors. Heterozygous mutations in the SOX2 gene are the most common monogenic form of anophthalmia/microphthalmia, as they are reported in up to 10-15% cases. Here, we describe a sporadic patient showing bilateral anophthalmia/microphthalmia and micropenis caused by a novel mutation (c.59_60insGG) in the SOX2 gene. Morphological and endocrinological evaluations excluded any anomaly of the hypothalamus-pituitary axis. Our finding supports the hypothesis that SOX2 is particularly prone to slipped-strand mispairing, which results in a high frequency of point deletions/insertions.

Defective photoreceptor phagocytosis in a mouse model of enhanced S-cone syndrome causes progressive retinal degeneration

PubMed Central

Mustafi, Debarshi; Kevany, Brian M.; Genoud, Christel; Okano, Kiichiro; Cideciyan, Artur V.; Sumaroka, Alexander; Roman, Alejandro J.; Jacobson, Samuel G.; Engel, Andreas; Adams, Mark D.; Palczewski, Krzysztof

2011-01-01

Enhanced S-cone syndrome (ESCS), featuring an excess number of S cones, manifests as a progressive retinal degeneration that leads to blindness. Here, through optical imaging, we identified an abnormal interface between photoreceptors and the retinal pigment epithelium (RPE) in 9 patients with ESCS. The neural retina leucine zipper transcription factor-knockout (Nrl−/−) mouse model demonstrates many phenotypic features of human ESCS, including unstable S-cone-positive photoreceptors. Using massively parallel RNA sequencing, we identified 6203 differentially expressed transcripts between wild-type (Wt) and Nrl−/− mouse retinas, with 6 highly significant differentially expressed genes of the Pax, Notch, and Wnt canonical pathways. Changes were also obvious in expression of 30 genes involved in the visual cycle and 3 key genes in photoreceptor phagocytosis. Novel high-resolution (100 nm) imaging and reconstruction of Nrl−/− retinas revealed an abnormal packing of photoreceptors that contributed to buildup of photoreceptor deposits. Furthermore, lack of phagosomes in the RPE layer of Nrl−/− retina revealed impairment in phagocytosis. Cultured RPE cells from Wt and Nrl−/− mice illustrated that the phagocytotic defect was attributable to the aberrant interface between ESCS photoreceptors and the RPE. Overcoming the retinal phagocytosis defect could arrest the progressive degenerative component of this disease.—Mustafi, D., Kevany, B. M., Genoud, C., Okano, K., Cideciyan, A. V., Sumaroka, A., Roman, A. J., Jacobson, S. G. Engel, A., Adams, M. D., Palczewski, K. Defective photoreceptor phagocytosis in a mouse model of enhanced S-cone syndrome causes progressive retinal degeneration. PMID:21659555

Molecular defects identified by whole exome sequencing in a child with Fanconi anemia.

PubMed

Zheng, Zhaojing; Geng, Juan; Yao, Ru-En; Li, Caihua; Ying, Daming; Shen, Yongnian; Ying, Lei; Yu, Yongguo; Fu, Qihua

2013-11-10

Fanconi anemia is a rare genetic disease characterized by bone marrow failure, multiple congenital malformations, and an increased susceptibility to malignancy. At least 15 genes have been identified that are involved in the pathogenesis of Fanconi anemia. However, it is still a challenge to assign the complementation group and to characterize the molecular defects in patients with Fanconi anemia. In the current study, whole exome sequencing was used to identify the affected gene(s) in a boy with Fanconi anemia. A recurring, non-synonymous mutation was found (c.3971C>T, p.P1324L) as well as a novel frameshift mutation (c.989_995del, p.H330LfsX2) in FANCA gene. Our results indicate that whole exome sequencing may be useful in clinical settings for rapid identification of disease-causing mutations in rare genetic disorders such as Fanconi anemia. © 2013 Elsevier B.V. All rights reserved.

[Genetic aspects in congenital hypothyrodism].

PubMed

Perone, Denise; Teixeira, Silvânia S; Clara, Sueli A; Santos, Daniela C dos; Nogueira, Célia R

2004-02-01

Congenital hypothyroidism (CH) affects between 1:3,000 and 1:4,000 newborns. Many genes are essential for normal development of the hypothalamus-pituitary-thyroid axis and hormone production, and are associated with CH. About 85% of primary hypothyroidism is called thyroid digenesis and evidence suggests that mutations in transcription factors (TTF2, TTF1, and PAX-8) and TSH receptor gene could be responsible for the disease. Genetic defects of hormone synthesis could be caused by mutations in the following genes: NIS (natrium-iodide symporter), pendrine, thyreoglobulin (TG), peroxidase (TPO). Recently, mutations in the THOX-2 gene have also been related to organification defects. Central hypothyroidism affects about 1:20,000 newborns and has been associated with mutations in pituitary transcriptional factors (POUIF1, PROP1, LHX3, and HESX1). The syndrome of resistance to thyroid hormone is rare, implies a hypothyroidism state for some tissues and is frequently associated with dominant autosomal mutations in the beta-receptor (TRss).

Deletion Analysis of the Tumorous-Head (tuh–3) Gene in DROSOPHILA MELANOGASTER

PubMed Central

Kuhn, David T.; Woods, Daniel F.; Andrew, Deborah J.

1981-01-01

In the presence of the naturally occurring maternal-effect alleles tuh-1h or tuh-1g, the tuh-3 mutant gene can cause the tumorous-head trait or the sac-testis trait. The tuh-3 gene functions as a semidominant in the presence of the tuh-1h maternal effect. Eye-antennal structures are replaced by posterior abdominal tergites and genital structures. If tuh-1h is replaced by its naturally occurring allele tuh-1g, tuh-3 functions as a recessive hypomorph and the defect switches from anterior to posterior structures, with a male genital-disc defect appearing with variable penetrance. Function and regulation of tuh-3+ may better be understood in light of the cytological localization of tuh-3 either adjacent to or as part of the bithorax complex. The tuh-3+ gene product appears to be essential for normal development, at least in the posterior end of the embryo. PMID:6804305

Genetics of human neural tube defects

PubMed Central

Greene, Nicholas D.E.; Stanier, Philip; Copp, Andrew J.

2009-01-01

Neural tube defects (NTDs) are common, severe congenital malformations whose causation involves multiple genes and environmental factors. Although more than 200 genes are known to cause NTDs in mice, there has been rather limited progress in delineating the molecular basis underlying most human NTDs. Numerous genetic studies have been carried out to investigate candidate genes in cohorts of patients, with particular reference to those that participate in folate one-carbon metabolism. Although the homocysteine remethylation gene MTHFR has emerged as a risk factor in some human populations, few other consistent findings have resulted from this approach. Similarly, attention focused on the human homologues of mouse NTD genes has contributed only limited positive findings to date, although an emerging association between genes of the non-canonical Wnt (planar cell polarity) pathway and NTDs provides candidates for future studies. Priorities for the next phase of this research include: (i) larger studies that are sufficiently powered to detect significant associations with relatively minor risk factors; (ii) analysis of multiple candidate genes in groups of well-genotyped individuals to detect possible gene–gene interactions; (iii) use of high throughput genomic technology to evaluate the role of copy number variants and to detect ‘private’ and regulatory mutations, neither of which have been studied to date; (iv) detailed analysis of patient samples stratified by phenotype to enable, for example, hypothesis-driven testing of candidates genes in groups of NTDs with specific defects of folate metabolism, or in groups of fetuses with well-defined phenotypes such as craniorachischisis. PMID:19808787

Bone regeneration with active angiogenesis by basic fibroblast growth factor gene transfected mesenchymal stem cells seeded on porous beta-TCP ceramic scaffolds.

PubMed

Guo, Xiaodong; Zheng, Qixin; Kulbatski, Iris; Yuan, Quan; Yang, Shuhua; Shao, Zengwu; Wang, Hong; Xiao, Baojun; Pan, Zhengqi; Tang, Shuo

2006-09-01

Large segmental bone defect repair remains a clinical and scientific challenge with increasing interest focused on combining gene transfer with tissue engineering techniques. Basic fibroblast growth factor (bFGF) is one of the most prominent osteogenic growth factors that has the potential to accelerate bone healing by promoting the proliferation and differentiation of mesenchymal stem cells (MSCs) and the regeneration of capillary vasculature. However, the short biological half-lives of growth factors may impose severe restraints on their clinical usefulness. Gene-based delivery systems provide a better way of achieving a sustained high concentration of growth factors locally in the defect and delivering a more biologically active product than that achieved by exogenous application of recombinant proteins. The objective of this experimental study was to investigate whether the bFGF gene modified MSCs could enhance the repair of large segmental bone defects. The pcDNA3-bFGF gene transfected MSCs were seeded on biodegradable porous beta tricalcium phosphate (beta-TCP) ceramics and allografted into the 15 mm critical-sized segmental bone defects in the radius of 18 New Zealand White rabbits. The pcDNA3 vector gene transfected MSCs were taken as the control. The follow-up times were 2, 4, 6, 8, 10 and 12 weeks. Scanning electron microscopic, roentgenographic, histologic and immunohistological studies were used to assess angiogenesis and bone regeneration. In vitro, the proliferation and differentiation of bFGF gene transfected MSCs were more active than that of the control groups. In vivo, significantly more new bone formation accompanied by abundant active capillary regeneration was observed in pores of the ceramics loaded with bFGF gene transfected MSCs, compared with control groups. Transfer of gene encoding bFGF to MSCs increases their osteogenic properties by enhancing capillary regeneration, thus providing a rich blood supply for new bone formation. This new bFGF gene enhanced tissue engineering strategy could be of potential benefit to accelerate bone healing, especially in defects caused by atrophic nonunion and avascular necrosis of the femoral head.

EMBRYOLOGY OF THE LITTLE AND BAGG X-RAYED MOUSE STOCK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carter, T.C.

1959-12-01

The morphology and development of the many defects in mice of the Little and Bagg x-rayed stock have been reinvestigated in an attempt to resolve the conflicts in the findings of earlier investigators. The observation that blebs occur on pseudencephalic embryos is incompatible with Bonnevie's hypothesis that they originate as cerebrospinal fluid in the myelencephalon; other observations support Plagens' hypothesis that the blebs originate as mesenchymal intercellular fluid. No unitary gene action was found. Four pedigrees of causes were constructed covering, respectively, defects of the central nervous system, bleb- induced lesions and defects of the body wall, morphological defects ofmore » the hind limbs, and defects of the urogenital system; there were cross-correlations between defects in the first three pedigrees, but the underlying mechanisms were not identified. (auth)« less

Study in Mice Links Key Signaling Molecule to Underlying Cause of Osteogenesis Imperfecta

MedlinePlus

... by mutations in a gene that codes for collagen, an abundant structural component of bone. This type ... linked to defects in enzymes that help process collagen to its mature form. These types of OI ...

The Combined Action of Duplicated Boron Transporters Is Required for Maize Growth in Boron-Deficient Conditions.

PubMed

Chatterjee, Mithu; Liu, Qiujie; Menello, Caitlin; Galli, Mary; Gallavotti, Andrea

2017-08-01

The micronutrient boron is essential in maintaining the structure of plant cell walls and is critical for high yields in crop species. Boron can move into plants by diffusion or by active and facilitated transport mechanisms. We recently showed that mutations in the maize boron efflux transporter ROTTEN EAR (RTE) cause severe developmental defects and sterility. RTE is part of a small gene family containing five additional members ( RTE2 - RTE6 ) that show tissue-specific expression. The close paralogous gene RTE2 encodes a protein with 95% amino acid identity with RTE and is similarly expressed in shoot and root cells surrounding the vasculature. Despite sharing a similar function with RTE , mutations in the RTE2 gene do not cause growth defects in the shoot, even in boron-deficient conditions. However, rte2 mutants strongly enhance the rte phenotype in soils with low boron content, producing shorter plants that fail to form all reproductive structures. The joint action of RTE and RTE2 is also required in root development. These defects can be fully complemented by supplying boric acid, suggesting that diffusion or additional transport mechanisms overcome active boron transport deficiencies in the presence of an excess of boron. Overall, these results suggest that RTE2 and RTE function are essential for maize shoot and root growth in boron-deficient conditions. Copyright © 2017 by the Genetics Society of America.

Monogenic syndromes of abnormal glucose homeostasis: clinical review and relevance to the understanding of the pathology of insulin resistance and ß cell failure

PubMed Central

Porter, J; Barrett, T

2005-01-01

Type 2 diabetes mellitus is caused by a combination of insulin resistance and ß cell failure. The polygenic nature of type 2 diabetes has made it difficult to study. Although many candidate genes for this condition have been suggested, in most cases association studies have been equivocal. Monogenic forms of diabetes have now been studied extensively, and the genetic basis of many of these syndromes has been elucidated, leading to greater understanding of the functions of the genes involved. Common variations in the genes causing monogenic disorders have been associated with susceptibility to type 2 diabetes in several populations and explain some of the linkage seen in genome-wide scans. Monogenic disorders are also helpful in understanding both normal and disordered glucose and insulin metabolism. Three main areas of defect contribute to diabetes: defects in insulin signalling leading to insulin resistance; defects of insulin secretion leading to hypoinsulinaemia; and apoptosis leading to decreased ß cell mass. These three pathological pathways are reviewed, focusing on rare genetic syndromes which have diabetes as a prominent feature. Apoptosis seems to be a final common pathway in both type 1 and type 2 diabetes. Study of rare forms of diabetes may help ion determining new therapeutic targets to preserve or increase ß cell mass and function. PMID:15772126

Congenital Heart Disease: Causes, Diagnosis, Symptoms, and Treatments.

PubMed

Sun, RongRong; Liu, Min; Lu, Lei; Zheng, Yi; Zhang, Peiying

2015-07-01

The congenital heart disease includes abnormalities in heart structure that occur before birth. Such defects occur in the fetus while it is developing in the uterus during pregnancy. About 500,000 adults have congenital heart disease in USA (WebMD, Congenital heart defects medications, www.WebMD.com/heart-disease/tc/congenital-heart-defects-medications , 2014). 1 in every 100 children has defects in their heart due to genetic or chromosomal abnormalities, such as Down syndrome. The excessive alcohol consumption during pregnancy and use of medications, maternal viral infection, such as Rubella virus, measles (German), in the first trimester of pregnancy, all these are risk factors for congenital heart disease in children, and the risk increases if parent or sibling has a congenital heart defect. These are heart valves defects, atrial and ventricular septa defects, stenosis, the heart muscle abnormalities, and a hole inside wall of the heart which causes defect in blood circulation, heart failure, and eventual death. There are no particular symptoms of congenital heart disease, but shortness of breath and limited ability to do exercise, fatigue, abnormal sound of heart as heart murmur, which is diagnosed by a physician while listening to the heart beats. The echocardiogram or transesophageal echocardiogram, electrocardiogram, chest X-ray, cardiac catheterization, and MRI methods are used to detect congenital heart disease. Several medications are given depending on the severity of this disease, and catheter method and surgery are required for serious cases to repair heart valves or heart transplantation as in endocarditis. For genetic study, first DNA is extracted from blood followed by DNA sequence analysis and any defect in nucleotide sequence of DNA is determined. For congenital heart disease, genes in chromosome 1 show some defects in nucleotide sequence. In this review the causes, diagnosis, symptoms, and treatments of congenital heart disease are described.

A novel mutation in DDR2 causing spondylo-meta-epiphyseal dysplasia with short limbs and abnormal calcifications (SMED-SL) results in defective intra-cellular trafficking

PubMed Central

2014-01-01

Background The rare autosomal genetic disorder, Spondylo-meta-epiphyseal dysplasia with short limbs and abnormal calcifications (SMED-SL), is reported to be caused by missense or splice site mutations in the human discoidin domain receptor 2 (DDR2) gene. Previously our group has established that trafficking defects and loss of ligand binding are the underlying cellular mechanisms of several SMED-SL causing mutations. Here we report the clinical characteristics of two siblings of consanguineous marriage with suspected SMED-SL and identification of a novel disease-causing mutation in the DDR2 gene. Methods Clinical evaluation and radiography were performed to evaluate the patients. All the coding exons and splice sites of the DDR2 gene were sequenced by Sanger sequencing. Subcellular localization of the mutated DDR2 protein was determined by confocal microscopy, deglycosylation assay and Western blotting. DDR2 activity was measured by collagen activation and Western analysis. Results In addition to the typical features of SMED-SL, one of the patients has an eye phenotype including visual impairment due to optic atrophy. DNA sequencing revealed a novel homozygous dinucleotide deletion mutation (c.2468_2469delCT) on exon 18 of the DDR2 gene in both patients. The mutation resulted in a frameshift leading to an amino acid change at position S823 and a predicted premature termination of translation (p.S823Cfs*2). Subcellular localization of the mutant protein was analyzed in mammalian cell lines, and it was found to be largely retained in the endoplasmic reticulum (ER), which was further supported by its N-glycosylation profile. In keeping with its cellular mis-localization, the mutant protein was found to be deficient in collagen-induced receptor activation, suggesting protein trafficking defects as the major cellular mechanism underlying the loss of DDR2 function in our patients. Conclusions Our results indicate that the novel mutation results in defective trafficking of the DDR2 protein leading to loss of function and disease. This confirms our previous findings that DDR2 missense mutations occurring at the kinase domain result in retention of the mutant protein in the ER. PMID:24725993

Neuron-specific knockdown of the Drosophila fat induces reduction of life span, deficient locomotive ability, shortening of motoneuron terminal branches and defects in axonal targeting.

PubMed

Nakamura, Aya; Tanaka, Ryo; Morishita, Kazushige; Yoshida, Hideki; Higuchi, Yujiro; Takashima, Hiroshi; Yamaguchi, Masamitsu

2017-07-01

Mutations in FAT4 gene, one of the human FAT family genes, have been identified in Van Maldergem syndrome (VMS) and Hennekam lymphangiectasia-lymphedema syndrome (HS). The FAT4 gene encodes a large protein with extracellular cadherin repeats, EGF-like domains and Laminin G-like domains. FAT4 plays a role in tumor suppression and planar cell polarity. Drosophila contains a human FAT4 homologue, fat. Drosophila fat has been mainly studied with Drosophila eye and wing systems. Here, we specially knocked down Drosophila fat in nerve system. Neuron-specific knockdown of fat shortened the life span and induced the defect in locomotive abilities of adult flies. In consistent with these phenotypes, defects in synapse structure at neuromuscular junction were observed in neuron-specific fat-knockdown flies. In addition, aberrations in axonal targeting of photoreceptor neuron in third-instar larvae were also observed, suggesting that fat involves in axonal targeting. Taken together, the results indicate that Drosophila fat plays an essential role in formation and/or maintenance of neuron. Both VMS and HS show mental retardation and neuronal defects. We therefore consider that these two rare human diseases could possibly be caused by the defect in FAT4 function in neuronal cells. © 2017 Molecular Biology Society of Japan and John Wiley & Sons Australia, Ltd.

Fanconi anemia and homologous recombination gene variants are associated with functional DNA repair defects in vitro and poor outcome in patients with advanced head and neck squamous cell carcinoma

PubMed Central

Verhagen, Caroline V.M.; Vossen, David M.; Borgmann, Kerstin; Hageman, Floor; Grénman, Reidar; Verwijs-Janssen, Manon; Mout, Lisanne; Kluin, Roel J.C.; Nieuwland, Marja; Severson, Tesa M.; Velds, Arno; Kerkhoven, Ron; O’Connor, Mark J.; van der Heijden, Martijn; van Velthuysen, Marie-Louise; Verheij, Marcel; Wreesmann, Volkert B.; Wessels, Lodewyk F.A.; van den Brekel, Michiel W.M.; Vens, Conchita

2018-01-01

Mutations in Fanconi Anemia or Homologous Recombination (FA/HR) genes can cause DNA repair defects and could therefore impact cancer treatment response and patient outcome. Their functional impact and clinical relevance in head and neck squamous cell carcinoma (HNSCC) is unknown. We therefore questioned whether functional FA/HR defects occurred in HNSCC and whether they are associated with FA/HR variants. We assayed a panel of 29 patient-derived HNSCC cell lines and found that a considerable fraction is hypersensitive to the crosslinker Mitomycin C and PARP inhibitors, a functional measure of FA/HR defects. DNA sequencing showed that these hypersensitivities are associated with the presence of bi-allelic rare germline and somatic FA/HR gene variants. We next questioned whether such variants are associated with prognosis and treatment response in HNSCC patients. DNA sequencing of 77 advanced stage HNSCC tumors revealed a 19% incidence of such variants. Importantly, these variants were associated with a poor prognosis (p = 0.027; HR = 2.6, 1.1–6.0) but favorable response to high cumulative cisplatin dose. We show how an integrated in vitro functional repair and genomic analysis can improve the prognostic value of genetic biomarkers. We conclude that repair defects are marked and frequent in HNSCC and are associated with clinical outcome. PMID:29719599

Fanconi anemia and homologous recombination gene variants are associated with functional DNA repair defects in vitro and poor outcome in patients with advanced head and neck squamous cell carcinoma.

PubMed

Verhagen, Caroline V M; Vossen, David M; Borgmann, Kerstin; Hageman, Floor; Grénman, Reidar; Verwijs-Janssen, Manon; Mout, Lisanne; Kluin, Roel J C; Nieuwland, Marja; Severson, Tesa M; Velds, Arno; Kerkhoven, Ron; O'Connor, Mark J; van der Heijden, Martijn; van Velthuysen, Marie-Louise; Verheij, Marcel; Wreesmann, Volkert B; Wessels, Lodewyk F A; van den Brekel, Michiel W M; Vens, Conchita

2018-04-06

Mutations in Fanconi Anemia or Homologous Recombination (FA/HR) genes can cause DNA repair defects and could therefore impact cancer treatment response and patient outcome. Their functional impact and clinical relevance in head and neck squamous cell carcinoma (HNSCC) is unknown. We therefore questioned whether functional FA/HR defects occurred in HNSCC and whether they are associated with FA/HR variants. We assayed a panel of 29 patient-derived HNSCC cell lines and found that a considerable fraction is hypersensitive to the crosslinker Mitomycin C and PARP inhibitors, a functional measure of FA/HR defects. DNA sequencing showed that these hypersensitivities are associated with the presence of bi-allelic rare germline and somatic FA/HR gene variants. We next questioned whether such variants are associated with prognosis and treatment response in HNSCC patients. DNA sequencing of 77 advanced stage HNSCC tumors revealed a 19% incidence of such variants. Importantly, these variants were associated with a poor prognosis ( p = 0.027; HR = 2.6, 1.1-6.0) but favorable response to high cumulative cisplatin dose. We show how an integrated in vitro functional repair and genomic analysis can improve the prognostic value of genetic biomarkers. We conclude that repair defects are marked and frequent in HNSCC and are associated with clinical outcome.

Coordinated Gene Regulation in the Initial Phase of Salt Stress Adaptation*

PubMed Central

Vanacloig-Pedros, Elena; Bets-Plasencia, Carolina; Pascual-Ahuir, Amparo; Proft, Markus

2015-01-01

Stress triggers complex transcriptional responses, which include both gene activation and repression. We used time-resolved reporter assays in living yeast cells to gain insights into the coordination of positive and negative control of gene expression upon salt stress. We found that the repression of “housekeeping” genes coincides with the transient activation of defense genes and that the timing of this expression pattern depends on the severity of the stress. Moreover, we identified mutants that caused an alteration in the kinetics of this transcriptional control. Loss of function of the vacuolar H+-ATPase (vma1) or a defect in the biosynthesis of the osmolyte glycerol (gpd1) caused a prolonged repression of housekeeping genes and a delay in gene activation at inducible loci. Both mutants have a defect in the relocation of RNA polymerase II complexes at stress defense genes. Accordingly salt-activated transcription is delayed and less efficient upon partially respiratory growth conditions in which glycerol production is significantly reduced. Furthermore, the loss of Hog1 MAP kinase function aggravates the loss of RNA polymerase II from housekeeping loci, which apparently do not accumulate at inducible genes. Additionally the Def1 RNA polymerase II degradation factor, but not a high pool of nuclear polymerase II complexes, is needed for efficient stress-induced gene activation. The data presented here indicate that the finely tuned transcriptional control upon salt stress is dependent on physiological functions of the cell, such as the intracellular ion balance, the protective accumulation of osmolyte molecules, and the RNA polymerase II turnover. PMID:25745106

The lipodystrophic hotspot lamin A p.R482W mutation deregulates the mesodermal inducer T/Brachyury and early vascular differentiation gene networks.

PubMed

Briand, Nolwenn; Guénantin, Anne-Claire; Jeziorowska, Dorota; Shah, Akshay; Mantecon, Matthieu; Capel, Emilie; Garcia, Marie; Oldenburg, Anja; Paulsen, Jonas; Hulot, Jean-Sebastien; Vigouroux, Corinne; Collas, Philippe

2018-04-15

The p.R482W hotspot mutation in A-type nuclear lamins causes familial partial lipodystrophy of Dunnigan-type (FPLD2), a lipodystrophic syndrome complicated by early onset atherosclerosis. Molecular mechanisms underlying endothelial cell dysfunction conferred by the lamin A mutation remain elusive. However, lamin A regulates epigenetic developmental pathways and mutations could perturb these functions. Here, we demonstrate that lamin A R482W elicits endothelial differentiation defects in a developmental model of FPLD2. Genome modeling in fibroblasts from patients with FPLD2 caused by the lamin A R482W mutation reveals repositioning of the mesodermal regulator T/Brachyury locus towards the nuclear center relative to normal fibroblasts, suggesting enhanced activation propensity of the locus in a developmental model of FPLD2. Addressing this issue, we report phenotypic and transcriptional alterations in mesodermal and endothelial differentiation of induced pluripotent stem cells we generated from a patient with R482W-associated FPLD2. Correction of the LMNA mutation ameliorates R482W-associated phenotypes and gene expression. Transcriptomics links endothelial differentiation defects to decreased Polycomb-mediated repression of the T/Brachyury locus and over-activation of T target genes. Binding of the Polycomb repressor complex 2 to T/Brachyury is impaired by the mutated lamin A network, which is unable to properly associate with the locus. This leads to a deregulation of vascular gene expression over time. By connecting a lipodystrophic hotspot lamin A mutation to a disruption of early mesodermal gene expression and defective endothelial differentiation, we propose that the mutation rewires the fate of several lineages, resulting in multi-tissue pathogenic phenotypes.

Velo-Cardio-Facial syndrome and DiGeorge sequence with meningomyelocele and deletions of the 22q11 region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nickel, R.E.; Pillers, D.M.; Merkens, M.

Approximately 5% of children with neural tube defects (NTDs) have a congenital heart defect and/or cleft lip and palate. The cause of isolated meningomyelocele, congenital heart defects, or cleft lip and palate has been largely thought to be multifactorial. However, chromosomal, teratogenic, and single gene causes of combinations of NTDs with congenital heart defects and/or cleft lip and palate have been reported. We report on 3 patients with meningomyelocele, congenital heart defects, and 22q11 deletions. Two of the children had the clinical diagnosis of velo-cardio-facial syndrome (VCFS); both have bifid uvula. The third child had DiGeorge sequence (DGS). The associationmore » of NTDs with 22q11 deletion has not been reported previously. An accurate diagnosis of the 22q11 deletion is critical as this micro-deletion and its associated clinical problems is transmitted as an autosomal dominant trait due to the inheritance of the deletion-bearing chromosome. We recommend that all children with NTDs and congenital heart defects, with or without cleft palate, have cytogenetic and molecular studies performed to detect 22q11 deletions. 31 refs., 3 figs.« less

The multiple genetic causes of central hypothyroidism.

PubMed

Persani, Luca; Bonomi, Marco

2017-03-01

An insufficient stimulation by thyrotropin (TSH) of an otherwise normal thyroid gland represents the cause of Central Hypothyrodism (CeH). CeH is about 1000-folds rarer than Primary Hypothyroidism and often represents a real challenge for the clinicians, mainly because they cannot rely on adequately sensitive parameters for diagnosis or management, as it occurs with circulating TSH in PH. Therefore, CeH diagnosis can be frequently missed or delayed in patients with a previously unknown pituitary involvement. A series of genetic defects have been described to account for isolated CeH or combined pituitary hormone defects (CPHDs) with variable clinical characteristics and degrees of severity. The recently identified candidate gene IGSF1 appears frequently involved. This review provides an updated illustration of the different genetic defects accounting for CeH. Copyright © 2017 Elsevier Ltd. All rights reserved.

Defective ciliogenesis, embryonic lethality and severe impairment of the Sonic Hedgehog pathway caused by inactivation of the mouse complex A intraflagellar transport gene Ift122/Wdr10, partially overlapping with the DNA repair gene Med1/Mbd4

PubMed Central

Cortellino, Salvatore; Wang, Chengbing; Wang, Baolin; Bassi, Maria Rosaria; Caretti, Elena; Champeval, Delphine; Calmont, Amelie; Jarnik, Michal; Burch, John; Zaret, Kenneth; Larue, Lionel; Bellacosa, Alfonso

2009-01-01

Primary cilia are assembled and maintained by evolutionarily conserved intraflagellar transport (IFT) proteins that are involved in the coordinated movement of macromolecular cargo from the basal body to the cilium tip and back. The IFT machinery is organized in two structural complexes named complex A and complex B. Recently, inactivation in the mouse germline of Ift genes belonging to complex B revealed a requirement of ciliogenesis, or proteins involved in ciliogenesis, for Sonic Hedgehog (Shh) signaling in mammals. Here we report on a complex A mutant mouse, defective for the Ift122 gene. Ift122-null embryos show multiple developmental defects (exencephaly, situs viscerum inversus, delay in turning, hemorrhage and defects in limb development) that result in lethality. In the node, primary cilia were absent or malformed in homozygous mutant and heterozygous embryos, respectively. Impairment of the Shh pathway was apparent in both neural tube patterning (expansion of motoneurons and rostro-caudal level-dependent contraction or expansion of the dorso-lateral interneurons), and limb patterning (ectrosyndactyly). These phenotypes are distinct from both complex B IFT mutant embryos and embryos defective for the ciliary protein hennin/Arl13b, and suggest reduced levels of both Gli2/Gli3 activator and Gli3 repressor functions. We conclude that complex A and complex B factors play similar but distinct roles in ciliogenesis and Shh/Gli3 signaling. PMID:19000668

Non-muscle myosin IIB (Myh10) is required for epicardial function and coronary vessel formation during mammalian development

PubMed Central

Mitchell, Karen; Al-Anbaki, Ali; Shaikh Qureshi, Wasay Mohiuddin; Tenin, Gennadiy; Lu, Yinhui; Clowes, Christopher; Robertson, Abigail; Barnes, Emma; Wright, Jayne A.; Keavney, Bernard; Lovell, Simon C.

2017-01-01

The coronary vasculature is an essential vessel network providing the blood supply to the heart. Disruptions in coronary blood flow contribute to cardiac disease, a major cause of premature death worldwide. The generation of treatments for cardiovascular disease will be aided by a deeper understanding of the developmental processes that underpin coronary vessel formation. From an ENU mutagenesis screen, we have isolated a mouse mutant displaying embryonic hydrocephalus and cardiac defects (EHC). Positional cloning and candidate gene analysis revealed that the EHC phenotype results from a point mutation in a splice donor site of the Myh10 gene, which encodes NMHC IIB. Complementation testing confirmed that the Myh10 mutation causes the EHC phenotype. Characterisation of the EHC cardiac defects revealed abnormalities in myocardial development, consistent with observations from previously generated NMHC IIB null mouse lines. Analysis of the EHC mutant hearts also identified defects in the formation of the coronary vasculature. We attribute the coronary vessel abnormalities to defective epicardial cell function, as the EHC epicardium displays an abnormal cell morphology, reduced capacity to undergo epithelial-mesenchymal transition (EMT), and impaired migration of epicardial-derived cells (EPDCs) into the myocardium. Our studies on the EHC mutant demonstrate a requirement for NMHC IIB in epicardial function and coronary vessel formation, highlighting the importance of this protein in cardiac development and ultimately, embryonic survival. PMID:29084269

SMAD4 Defect Causes Auditory Neuropathy Via Specialized Disruption of Cochlear Ribbon Synapses in Mice.

PubMed

Liu, Ke; Ji, Fei; Yang, Guan; Hou, Zhaohui; Sun, Jianhe; Wang, Xiaoyu; Guo, Weiwei; Sun, Wei; Yang, Weiyan; Yang, Xiao; Yang, Shiming

2016-10-01

More than 100 genes have been associated with deafness. However, SMAD4 is rarely considered a contributor to deafness in humans, except for its well-defined role in cell differentiation and regeneration. Here, we report that a SMAD4 defect in mice can cause auditory neuropathy, which was defined as a mysterious hearing and speech perception disorder in human for which the genetic background remains unclear. Our study showed that a SMAD4 defect induces failed formation of cochlear ribbon synapse during the earlier stage of auditory development in mice. Further investigation found that there are nearly normal morphology of outer hair cells (OHCs) and post-synapse spiral ganglion nerves (SGNs) in SMAD4 conditional knockout mice (cKO); however, a preserved distortion product of otoacoustic emission (DPOAE) and cochlear microphonic (CM) still can be evoked in cKO mice. Moreover, a partial restoration of hearing detected by electric auditory brainstem response (eABR) has been obtained in the cKO mice using electrode stimuli toward auditory nerves. Additionally, the ribbon synapses in retina are not affected by this SMAD4 defect. Thus, our findings suggest that this SMAD4 defect causes auditory neuropathy via specialized disruption of cochlear ribbon synapses.

Differential Expression of Putative Polyketide Biosynthetic Gene Clusters in Fusarium verticillioides

USDA-ARS?s Scientific Manuscript database

The maize pathogen Fusarium verticillioides can produce a number of polyketide derived secondary metabolites, including fumonisins. Fumonisins cause diseases in animals, and show epidemiological correlation with esophageal cancer and birth defects in humans. The F. verticillioides genome contains ...

A glycogene mutation map for discovery of diseases of glycosylation

PubMed Central

Hansen, Lars; Lind-Thomsen, Allan; Joshi, Hiren J; Pedersen, Nis Borbye; Have, Christian Theil; Kong, Yun; Wang, Shengjun; Sparso, Thomas; Grarup, Niels; Vester-Christensen, Malene Bech; Schjoldager, Katrine; Freeze, Hudson H; Hansen, Torben; Pedersen, Oluf; Henrissat, Bernard; Mandel, Ulla; Clausen, Henrik; Wandall, Hans H; Bennett, Eric P

2015-01-01

Glycosylation of proteins and lipids involves over 200 known glycosyltransferases (GTs), and deleterious defects in many of the genes encoding these enzymes cause disorders collectively classified as congenital disorders of glycosylation (CDGs). Most known CDGs are caused by defects in glycogenes that affect glycosylation globally. Many GTs are members of homologous isoenzyme families and deficiencies in individual isoenzymes may not affect glycosylation globally. In line with this, there appears to be an underrepresentation of disease-causing glycogenes among these larger isoenzyme homologous families. However, genome-wide association studies have identified such isoenzyme genes as candidates for different diseases, but validation is not straightforward without biomarkers. Large-scale whole-exome sequencing (WES) provides access to mutations in, for example, GT genes in populations, which can be used to predict and/or analyze functional deleterious mutations. Here, we constructed a draft of a functional mutational map of glycogenes, GlyMAP, from WES of a rather homogenous population of 2000 Danes. We cataloged all missense mutations and used prediction algorithms, manual inspection and in case of carbohydrate-active enzymes family GT27 experimental analysis of mutations to map deleterious mutations. GlyMAP (http://glymap.glycomics.ku.dk) provides a first global view of the genetic stability of the glycogenome and should serve as a tool for discovery of novel CDGs. PMID:25267602

Changes is genes coding for laccases 1 and 2 may contribute to deformation and reduction of wings in apollo butterfly (Parnassius apollo, Lepidoptera: Papilionidae) from the isolated population in Pieniny National Park (Poland).

PubMed

Łukasiewicz, Kinga; Węgrzyn, Grzegorz

2016-01-01

An isolated population of apollo butterfly (Parnassius apollo, Lepidoptera: Papilionidae) occurs in Pieniny National Park (Poland). Deformations and reductions of wings in a relatively large number of individuals from this population is found, yet the reasons for these defects are unknown. During studies devoted to identify cause(s) of this phenomenon, we found that specific regions of genes coding of enzymes laccases 1 and 2 could not be amplified from DNA samples isolated from large fractions of malformed insects while expected PCR products were detected in almost all (with one exception) normal butterflies. Laccases (p-diphenol:dioxygen oxidoreductases) are oxidases containing several copper atoms. They catalyse single-electron oxidations of phenolic or other compounds with concomitant reduction of oxygen to water. In insects, their enzymatic activities were found previously in epidermis, midgut, Malpighian tubules, salivary glands, and reproductive tissues. Therefore, we suggest that defects in genes coding for laccases might contribute to deformation and reduction of wings in apollo butterflies, though it seems obvious that deficiency in these enzymes could not be the sole cause of these developmental improperties in P. apollo from Pieniny National Park.

Independent degeneration of photoreceptors and retinal pigment epithelium in conditional knockout mouse models of choroideremia

PubMed Central

Tolmachova, Tanya; Anders, Ross; Abrink, Magnus; Bugeon, Laurence; Dallman, Margaret J.; Futter, Clare E.; Ramalho, José S.; Tonagel, Felix; Tanimoto, Naoyuki; Seeliger, Mathias W.; Huxley, Clare; Seabra, Miguel C.

2006-01-01

Choroideremia (CHM) is an X-linked degeneration of the retinal pigment epithelium (RPE), photoreceptors, and choroid, caused by loss of function of the CHM/REP1 gene. REP1 is involved in lipid modification (prenylation) of Rab GTPases, key regulators of intracellular vesicular transport and organelle dynamics. To study the pathogenesis of CHM and to develop a model for assessing gene therapy, we have created a conditional mouse knockout of the Chm gene. Heterozygous-null females exhibit characteristic hallmarks of CHM: progressive degeneration of the photoreceptors, patchy depigmentation of the RPE, and Rab prenylation defects. Using tamoxifen-inducible and tissue-specific Cre expression in combination with floxed Chm alleles, we show that CHM pathogenesis involves independently triggered degeneration of photoreceptors and the RPE, associated with different subsets of defective Rabs. PMID:16410831

SLUG (SNAI2) deletions in patients with Waardenburg disease.

PubMed

Sánchez-Martín, Manuel; Rodríguez-García, Arancha; Pérez-Losada, Jesús; Sagrera, Ana; Read, Andrew P; Sánchez-García, Isidro

2002-12-01

Waardenburg syndrome (WS; deafness with pigmentary abnormalities) is a congenital disorder caused by defective function of the embryonic neural crest. Depending on additional symptoms, WS is classified into four types: WS1, WS2, WS3 and WS4. WS1 and WS3 are caused by mutations in PAX3, whereas WS2 is heterogenous, being caused by mutations in the microphthalmia (MITF) gene in some but not all affected families. The identification of Slugh, a zinc-finger transcription factor expressed in migratory neural crest cells, as the gene responsible for pigmentary disturbances in mice prompted us to analyse the role of its human homologue SLUG in neural crest defects. Here we show that two unrelated patients with WS2 have homozygous deletions in SLUG which result in absence of the SLUG product. We further show that Mitf is present in Slug-deficient cells and transactivates the SLUG promoter, and that Slugh and Kit genetically interact in vivo. Our findings further define the locus heterogeneity of WS2 and point to an essential role of SLUG in the development of neural crest-derived human cell lineages: its absence causes the auditory-pigmentary symptoms in at least some individuals with WS2.

Combining Zebrafish and Mouse Models to Test the Function of Deubiquitinating Enzyme (Dubs) Genes in Development: Role of USP45 in the Retina.

PubMed

Toulis, Vasileios; Garanto, Alejandro; Marfany, Gemma

2016-01-01

Ubiquitination is a dynamic and reversible posttranslational modification. Much effort has been devoted to characterize the function of ubiquitin pathway genes in the cell context, but much less is known on their functional role in the development and maintenance of organs and tissues in the organism. In fact, several ubiquitin ligases and deubiquitinating enzymes (DUBs) are implicated in human pathological disorders, from cancer to neurodegeneration. The aim of our work is to explore the relevance of DUBs in retinal function in health and disease, particularly since some genes related to the ubiquitin or SUMO pathways cause retinal dystrophies, a group of rare diseases that affect 1:3000 individuals worldwide. We propose zebrafish as an extremely useful and informative genetic model to characterize the function of any particular gene in the retina, and thus complement the expression data from mouse. A preliminary characterization of gene expression in mouse retinas (RT-PCR and in situ hybridization) was performed to select particularly interesting genes, and we later replicated the experiments in zebrafish. As a proof of concept, we selected ups45 to be knocked down by morpholino injection in zebrafish embryos. Morphant phenotypic analysis showed moderate to severe eye morphological defects, with a defective formation of the retinal structures, therefore supporting the relevance of DUBs in the formation and differentiation of the vertebrate retina, and suggesting that genes encoding ubiquitin pathway enzymes are good candidates for causing hereditary retinal dystrophies.

Charcot–Marie–Tooth disease and intracellular traffic

PubMed Central

Bucci, Cecilia; Bakke, Oddmund; Progida, Cinzia

2012-01-01

Mutations of genes whose primary function is the regulation of membrane traffic are increasingly being identified as the underlying causes of various important human disorders. Intriguingly, mutations in ubiquitously expressed membrane traffic genes often lead to cell type- or organ-specific disorders. This is particularly true for neuronal diseases, identifying the nervous system as the most sensitive tissue to alterations of membrane traffic. Charcot–Marie–Tooth (CMT) disease is one of the most common inherited peripheral neuropathies. It is also known as hereditary motor and sensory neuropathy (HMSN), which comprises a group of disorders specifically affecting peripheral nerves. This peripheral neuropathy, highly heterogeneous both clinically and genetically, is characterized by a slowly progressive degeneration of the muscle of the foot, lower leg, hand and forearm, accompanied by sensory loss in the toes, fingers and limbs. More than 30 genes have been identified as targets of mutations that cause CMT neuropathy. A number of these genes encode proteins directly or indirectly involved in the regulation of intracellular traffic. Indeed, the list of genes linked to CMT disease includes genes important for vesicle formation, phosphoinositide metabolism, lysosomal degradation, mitochondrial fission and fusion, and also genes encoding endosomal and cytoskeletal proteins. This review focuses on the link between intracellular transport and CMT disease, highlighting the molecular mechanisms that underlie the different forms of this peripheral neuropathy and discussing the pathophysiological impact of membrane transport genetic defects as well as possible future ways to counteract these defects. PMID:22465036

Value of transmission electron microscopy for primary ciliary dyskinesia diagnosis in the era of molecular medicine: Genetic defects with normal and non-diagnostic ciliary ultrastructure.

PubMed

Shapiro, Adam J; Leigh, Margaret W

2017-01-01

Primary ciliary dyskinesia (PCD) is a genetic disorder causing chronic oto-sino-pulmonary disease. No single diagnostic test will detect all PCD cases. Transmission electron microscopy (TEM) of respiratory cilia was previously considered the gold standard diagnostic test for PCD, but 30% of all PCD cases have either normal ciliary ultrastructure or subtle changes which are non-diagnostic. These cases are identified through alternate diagnostic tests, including nasal nitric oxide measurement, high-speed videomicroscopy analysis, immunofluorescent staining of axonemal proteins, and/or mutation analysis of various PCD causing genes. Autosomal recessive mutations in DNAH11 and HYDIN produce normal TEM ciliary ultrastructure, while mutations in genes encoding for radial spoke head proteins result in some cross-sections with non-diagnostic alterations in the central apparatus interspersed with normal ciliary cross-sections. Mutations in nexin link and dynein regulatory complex genes lead to a collection of different ciliary ultrastructures; mutations in CCDC65, CCDC164, and GAS8 produce normal ciliary ultrastructure, while mutations in CCDC39 and CCDC40 cause absent inner dynein arms and microtubule disorganization in some ciliary cross-sections. Mutations in CCNO and MCIDAS cause near complete absence of respiratory cilia due to defects in generation of multiple cellular basal bodies; however, the scant cilia generated may have normal ultrastructure. Lastly, a syndromic form of PCD with retinal degeneration results in normal ciliary ultrastructure through mutations in the RPGR gene. Clinicians must be aware of these genetic causes of PCD resulting in non-diagnostic TEM ciliary ultrastructure and refrain from using TEM of respiratory cilia as a test to rule out PCD.

Pathology of Podocytopathies Causing Nephrotic Syndrome in Children.

PubMed

Ranganathan, Sarangarajan

2016-01-01

Nephrotic syndrome (NS) in children includes a diverse group of diseases that range from genetic diseases without any immunological defects to causes that are primarily due to immunological effects. Recent advances in molecular and genomic studies have resulted in a plethora of genetic defects that have been localized to the podocyte, the basic structure that is instrumental in normal filtration process. Although the disease can manifest from birth and into adulthood, the primary focus of this review would be to describe the novel genes and pathology of primary podocyte defects that cause NS in children. This review will restrict itself to the pathology of congenital NS, minimal change disease (MCD), and its variants and focal segmental glomerulosclerosis (FSGS). The two major types of congenital NS are Finnish type characterized by dilated sausage shaped tubules morphologically and diffuse mesangial sclerosis characterized by glomerulosclerosis. MCD has usually normal appearing biopsy features on light microscopy and needs electron microscopy for diagnosis, whereas FSGS in contrast has classic segmental sclerosing lesions identified in different portions of the glomeruli and tubular atrophy. This review summarizes the pathological characteristics of these conditions and also delves into the various genetic defects that have been described as the cause of these primary podocytopathies. Other secondary causes of NS in children, such as membranoproliferative and membranous glomerulonephritis, will not be covered in this review.

Sonic Hedgehog mutations are not a common cause of congenital hypopituitarism in the absence of complex midline cerebral defects.

PubMed

Paulo, Sabrina Soares; Fernandes-Rosa, Fábio L; Turatti, Wendy; Coeli-Lacchini, Fernanda Borchers; Martinelli, Carlos E; Nakiri, Guilherme S; Moreira, Ayrton C; Santos, Antônio C; de Castro, Margaret; Antonini, Sonir R

2015-04-01

Sonic Hedgehog (SHH) and GLI2, an obligatory mediator of SHH signal transduction, are holoprosencephaly (HPE)-associated genes essential in pituitary formation. GLI2 variants have been found in patients with congenital hypopituitarism without complex midline cerebral defects (MCD). However, data on the occurrence of SHH mutations in these patients are limited. We screened for SHH and GLI2 mutations or copy number variations (CNV) in patients with congenital hypopituitarism without MCD or with variable degrees of MCD. Detailed data on clinical, laboratory and neuroimaging findings of 115 patients presenting with congenital hypopituitarism without MCD, septo-optic dysplasia or HPE were analysed. The SHH and GLI2 genes were directly sequenced, and the presence of gene CNV was analysed by multiplex ligation-dependent probe amplification (MLPA). Anterior pituitary deficiency was found in 74% and 53% of patients with SOD or HPE, respectively. Diabetes insipidus was common in patients with HPE (47%) but infrequent in patients with congenital hypopituitarism or SOD (7% and 8%, respectively). A single heterozygous nonsense SHH mutation (p.Tyr175Ter) was found in a patient presenting with hypopituitarism and alobar HPE. No other SHH mutations or CNV were found. Nine GLI2 variations (8 missense and 1 frameshift) including a homozygous and a compound heterozygous variation were found in patients with congenital hypopituitarism or SOD, but not in HPE patients. No GLI2 CNV were found. SHH mutations or copy number variations are not a common cause of congenital hypopituitarism in patients without complex midline cerebral defects. GLI2 variants are found in some patients with congenital hypopituitarism without complex midline cerebral defects or septo-optic dysplasia. However, functional analyses of these variants are needed to strengthen genotype-phenotype relationship. © 2014 John Wiley & Sons Ltd.

Congenital heart defect causing mutation in Nkx2.5 displays in vivo functional deficit.

PubMed

Zakariyah, Abeer F; Rajgara, Rashida F; Veinot, John P; Skerjanc, Ilona S; Burgon, Patrick G

2017-04-01

The Nkx2.5 gene encodes a transcription factor that plays a critical role in heart development. In humans, heterozygous mutations in NKX2.5 result in congenital heart defects (CHDs). However, the molecular mechanisms by which these mutations cause the disease remain unknown. NKX2.5-R142C is a mutation that was reported to be associated with atrial septal defect (ASD) and atrioventricular (AV) block in 13-patients from one family. The R142C mutation is located within both the DNA-binding domain and the nuclear localization sequence of NKX2.5 protein. The pathogenesis of CHDs in humans with R142C point mutation is not well understood. To examine the functional deficit associated with this mutation in vivo, we generated and characterized a knock-in mouse that harbours the human mutation R142C. Systematic structural and functional examination of the embryonic, newborn, and adult mice revealed that the homozygous embryos Nkx2.5 R141C/R141C are developmentally arrested around E10.5 with delayed heart morphogenesis and downregulation of Nkx2.5 target genes, Anf, Mlc2v, Actc1 and Cx40. Histological examination of Nkx2.5 R141C/+ newborn hearts showed that 36% displayed ASD, with at least 80% 0f adult heterozygotes displaying a septal defect. Moreover, heterozygous Nkx2.5 R141C/+ newborn mice have downregulation of ion channel genes with 11/12 adult mice manifesting a prolonged PR interval that is indicative of 1st degree AV block. Collectively, the present study demonstrates that mice with the R141C point mutation in the Nkx2.5 allele phenocopies humans with the NKX2.5 R142C point mutation. Copyright © 2017 Elsevier Ltd. All rights reserved.

New treatments targeting the basic defects in cystic fibrosis.

PubMed

Fajac, Isabelle; Wainwright, Claire E

2017-06-01

Cystic fibrosis (CF) is a monogenic autosomal recessive disorder affecting around 75,000 individuals worldwide. It is a multi-system disease but the main morbidity and mortality is caused by chronic lung disease. Due to newborn screening, a multidisciplinary approach to care and intensive symptomatic treatment, the prognosis has dramatically improved over the last decades and there are currently more adults than children in many countries. However, CF is still a very severe disease with a current median age of life expectancy in the fourth decade of life. The disease is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene which encodes the CFTR protein, a protein kinase A-activated ATP-gated anion channel that regulates the transport of electrolytes such as chloride and bicarbonate. More than 2000 mutations have been reported, although not all of these have functional consequences. An enormous research effort and progress has been made in understanding the consequences of these mutations on the CFTR protein structure and function, and this has led to the approval of two new drug therapies that are able to bind to defective CFTR proteins and partially restore their function. They are mutation-specific therapies and available at present for specific mutations only. They are the first personalized medicine for CF with a possible disease-modifying effect. A pipeline of other compounds is under development with different mechanisms of action. It is foreseeable that new combinations of compounds will further improve the correction of CFTR function. Other strategies including premature stop codon read-through drugs, antisense oligonucleotides that correct the basic defect at the mRNA level or gene editing to restore the defective gene as well as gene therapy approaches are all in the pipeline. All these strategies are needed to develop disease-modifying therapies for all patients with CF. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Italian familial defective apolipoprotein B patients share a unique haplotype with other Caucasian patients.

PubMed

Cefalù, A B; Barbagallo, C M; Sesti, E; Caldarella, R; Polizzi, F; Marino, G; Noto, D; Rolleri, M; Travali, S; Scalisi, G; Notarbartolo, A; Corsini, A; Bertolini, S; Averna, M R

2001-09-01

Familial defective apolipoprotein (apo) B-100 together with familial hypercholesterolemia are the two common genetic conditions that cause hypercholesterolemia. Familial defective apolipoprotein B-100 is due to mutations around codon 3500 of the apo B gene. The most-characterized mutation is a G>A transition at nucleotide 10,708 that results in the substitution of arginine by glutamine at codon 3500 (Apo B Arg3500Gln). Two other mutations are caused by a C>T transition, one at nucleotide 10,800 (Apo B Arg3531Cys) and the other at nucleotide 10,707 (apo B Arg3500Trp). In the present study we describe three new Italian cases of familial defective apolipoprotein B-100 (Apo B Arg3500Gln), one from the Liguria region and two from Sicily, and the haplotype of the apo B gene co-segregating with the mutation. By screening two groups of probands, clinically diagnosed as having Familial Hypercholesterolemia (700 from mainland Italy and 305 from Sicily), the prevalence of familial defective apolipoprotein B-100 due to Arg3500Gln was found to be very low (0.28% and 0.65%, respectively). The Arg3531Cys mutation was not detected in any proband. In the three new families with Arg3500Gln mutation in the present study and in one previously described in Italy, the mutation was associated with a unique apo B haplotype, which is consistent with data previously reported for Caucasian patients [XbaI-, MspI+, EcoRI-, presence of the 5' signal peptide insertion (Ins) allele, and the 49-repeat allele of the 3'-VNTR].

An inherited immunoglobulin class-switch recombination deficiency associated with a defect in the INO80 chromatin remodeling complex

PubMed Central

Kracker, Sven; Di Virgilio, Michela; Schwartzentruber, Jeremy; Cuenin, Cyrille; Forveille, Monique; Deau, Marie-Céline; McBride, Kevin M.; Majewski, Jacek; Gazumyan, Anna; Seneviratne, Suranjith; Grimbacher, Bodo; Kutukculer, Necil; Herceg, Zdenko; Cavazzana, Marina; Jabado, Nada; Nussenzweig, Michel C.; Fischer, Alain; Durandy, Anne

2015-01-01

Background Immunoglobulin class-switch recombination defects (CSR-D) are rare primary immunodeficiencies characterized by impaired production of switched immunoglobulin isotypes and normal or elevated IgM levels. They are caused by impaired T:B cooperation or intrinsic B cell defects. However, many immunoglobulin CSR-Ds are still undefined at the molecular level. Objective This study's objective was to delineate new causes of immunoglobulin CSR-Ds and thus gain further insights into the process of immunoglobulin class-switch recombination (CSR). Methods Exome sequencing in 2 immunoglobulin CSR-D patients identified variations in the INO80 gene. Functional experiments were performed to assess the function of INO80 on immunoglobulin CSR. Results We identified recessive, nonsynonymous coding variations in the INO80 gene in 2 patients affected by defective immunoglobulin CSR. Expression of wild-type INO80 in patients' fibroblastic cells corrected their hypersensitivity to high doses of γ-irradiation. In murine CH12-F3 cells, the INO80 complex accumulates at Sα and Eμ regions of the IgH locus, and downregulation of INO80 as well as its partners Reptin and Pontin impaired CSR. In addition, Reptin and Pontin were shown to interact with activation-induced cytidine deaminase. Finally, an abnormal separation of sister chromatids was observed upon INO80 downregulation in CH12-F3 cells, pinpointing its role in cohesin activity. Conclusion INO80 deficiency appears to be associated with defective immunoglobulin CSR. We propose that the INO80 complex modulates cohesin function that may be required during immunoglobulin switch region synapsis. PMID:25312759

UDP-glucose Dehydrogenase Polymorphisms from Patients with Congenital Heart Valve Defects Disrupt Enzyme Stability and Quaternary Assembly*

PubMed Central

Hyde, Annastasia S.; Farmer, Erin L.; Easley, Katherine E.; van Lammeren, Kristy; Christoffels, Vincent M.; Barycki, Joseph J.; Bakkers, Jeroen; Simpson, Melanie A.

2012-01-01

Cardiac valve defects are a common congenital heart malformation and a significant clinical problem. Defining molecular factors in cardiac valve development has facilitated identification of underlying causes of valve malformation. Gene disruption in zebrafish revealed a critical role for UDP-glucose dehydrogenase (UGDH) in valve development, so this gene was screened for polymorphisms in a patient population suffering from cardiac valve defects. Two genetic substitutions were identified and predicted to encode missense mutations of arginine 141 to cysteine and glutamate 416 to aspartate, respectively. Using a zebrafish model of defective heart valve formation caused by morpholino oligonucleotide knockdown of UGDH, transcripts encoding the UGDH R141C or E416D mutant enzymes were unable to restore cardiac valve formation and could only partially rescue cardiac edema. Characterization of the mutant recombinant enzymes purified from Escherichia coli revealed modest alterations in the enzymatic activity of the mutants and a significant reduction in the half-life of enzyme activity at 37 °C. This reduction in activity could be propagated to the wild-type enzyme in a 1:1 mixed reaction. Furthermore, the quaternary structure of both mutants, normally hexameric, was destabilized to favor the dimeric species, and the intrinsic thermal stability of the R141C mutant was highly compromised. The results are consistent with the reduced function of both missense mutations significantly reducing the ability of UGDH to provide precursors for cardiac cushion formation, which is essential to subsequent valve formation. The identification of these polymorphisms in patient populations will help identify families genetically at risk for valve defects. PMID:22815472

Understanding α-globin gene regulation and implications for the treatment of β-thalassemia.

PubMed

Mettananda, Sachith; Gibbons, Richard J; Higgs, Douglas R

2016-03-01

Over the past three decades, a vast amount of new information has been uncovered describing how the globin genes are regulated. This knowledge has provided significant insights into the general understanding of the regulation of human genes. It is now known that molecular defects within and around the α- and β-globin genes, as well as in the distant regulatory elements, can cause thalassemia. Unbalanced production of globin chains owing to defective synthesis of one, and the continued unopposed synthesis of another, is the central causative factor in the cellular pathology and pathophysiology of thalassemia. A large body of clinical, genetic, and experimental evidence suggests that altering globin chain imbalance by reducing the production of α-globin synthesis ameliorates the disease severity in patients with β-thalassemia. With the development of new genetic-based therapeutic tools that have a potential to decrease the expression of a selected gene in a tissue-specific manner, the possibility of decreasing expression of the α-globin gene to improve the clinical severity of β-thalassemia could become a reality. © 2015 New York Academy of Sciences.

Targeting Nonsense Mutations in Diseases with Translational Read-Through-Inducing Drugs (TRIDs).

PubMed

Nagel-Wolfrum, Kerstin; Möller, Fabian; Penner, Inessa; Baasov, Timor; Wolfrum, Uwe

2016-04-01

In recent years, remarkable advances in the ability to diagnose genetic disorders have been made. The identification of disease-causing genes allows the development of gene-specific therapies with the ultimate goal to develop personalized medicines for each patient according to their own specific genetic defect. In-depth genotyping of many different genes has revealed that ~12% of inherited genetic disorders are caused by in-frame nonsense mutations. Nonsense (non-coding) mutations are caused by point mutations, which generate premature termination codons (PTCs) that cause premature translational termination of the mRNA, and subsequently inhibit normal full-length protein expression. Recently, a gene-based therapeutic approach for genetic diseases caused by nonsense mutations has emerged, namely the so-called translational read-through (TR) therapy. Read-through therapy is based on the discovery that small molecules, known as TR-inducing drugs (TRIDs), allow the translation machinery to suppress a nonsense codon, elongate the nascent peptide chain, and consequently result in the synthesis of full-length protein. Several TRIDs are currently under investigation and research has been performed on several genetic disorders caused by nonsense mutations over the years. These findings have raised hope for the usage of TR therapy as a gene-based pharmacogenetic therapy for nonsense mutations in various genes responsible for a variety of genetic diseases.

acn-1, a C. elegans homologue of ACE, genetically interacts with the let-7 microRNA and other heterochronic genes.

PubMed

Metheetrairut, Chanatip; Ahuja, Yuri; Slack, Frank J

2017-10-02

The heterochronic pathway in C. elegans controls the relative timing of cell fate decisions during post-embryonic development. It includes a network of microRNAs (miRNAs), such as let-7, and protein-coding genes, such as the stemness factors, LIN-28 and LIN-41. Here we identified the acn-1 gene, a homologue of mammalian angiotensin-converting enzyme (ACE), as a new suppressor of the stem cell developmental defects of let-7 mutants. Since acn-1 null mutants die during early larval development, we used RNAi to characterize the role of acn-1 in C. elegans seam cell development, and determined its interaction with heterochronic factors, including let-7 and its downstream interactors - lin-41, hbl-1, and apl-1. We demonstrate that although RNAi knockdown of acn-1 is insufficient to cause heterochronic defects on its own, loss of acn-1 suppresses the retarded phenotypes of let-7 mutants and enhances the precocious phenotypes of hbl-1, though not lin-41, mutants. Conversely, the pattern of acn-1 expression, which oscillates during larval development, is disrupted by lin-41 mutants but not by hbl-1 mutants. Finally, we show that acn-1(RNAi) enhances the let-7-suppressing phenotypes caused by loss of apl-1, a homologue of the Alzheimer's disease-causing amyloid precursor protein (APP), while significantly disrupting the expression of apl-1 during the L4 larval stage. In conclusion, acn-1 interacts with heterochronic genes and appears to function downstream of let-7 and its target genes, including lin-41 and apl-1.

Mouse Models for Investigating the Developmental Bases of Human Birth Defects

PubMed Central

MOON, ANNE M.

2006-01-01

Clinicians and basic scientists share an interest in discovering how genetic or environmental factors interact to perturb normal development and cause birth defects and human disease. Given the complexity of such interactions, it is not surprising that 4% of human infants are born with a congenital malformation, and cardiovascular defects occur in nearly 1%. Our research is based on the fundamental hypothesis that an understanding of normal and abnormal development will permit us to generate effective strategies for both prevention and treatment of human birth defects. Animal models are invaluable in these efforts because they allow one to interrogate the genetic, molecular and cellular events that distinguish normal from abnormal development. Several features of the mouse make it a particularly powerful experimental model: it is a mammalian system with similar embryology, anatomy and physiology to humans; genes, proteins and regulatory programs are largely conserved between human and mouse; and finally, gene targeting in murine embryonic stem cells has made the mouse genome amenable to sophisticated genetic manipulation currently unavailable in any other model organism. PMID:16641221

Biochemical and genetic analysis of Leigh syndrome patients in Korea.

PubMed

Chae, Jong-Hee; Lee, Jin Sook; Kim, Ki Joong; Hwang, Yong Seung; Hirano, Michio

2008-06-01

Sixteen Korean patients with Leigh syndrome were identified at the Seoul National University Children's Hospital in 2001-2006. Biochemical or molecular defects were identified in 14 patients (87.5%). Thirteen patients had respiratory chain enzyme defects; 9 had complex I deficiency, and 4 had combined defects of complex I+III+IV. Based on the biochemical defects, targeted genetic studies in 4 patients with complex I deficiency revealed two heteroplasmic mitochondrial DNA mutations in ND genes. One patient had the mitochondrial DNA T8993G point mutation. No mitochondrial DNA defects were identified in 11 (68.7%) of our LS patients, who probably have mutations in nuclear DNA. Although a limited study based in a single tertiary medical center, our findings suggest that isolated complex I deficiency may be the most common cause of Leigh syndrome in Korea.

Using whole-exome sequencing to investigate the genetic bases of lysosomal storage diseases of unknown etiology.

PubMed

Wang, Nan; Zhang, Yeting; Gedvilaite, Erika; Loh, Jui Wan; Lin, Timothy; Liu, Xiuping; Liu, Chang-Gong; Kumar, Dibyendu; Donnelly, Robert; Raymond, Kimiyo; Schuchman, Edward H; Sleat, David E; Lobel, Peter; Xing, Jinchuan

2017-11-01

Lysosomes are membrane-bound, acidic eukaryotic cellular organelles that play important roles in the degradation of macromolecules. Mutations that cause the loss of lysosomal protein function can lead to a group of disorders categorized as the lysosomal storage diseases (LSDs). Suspicion of LSD is frequently based on clinical and pathologic findings, but in some cases, the underlying genetic and biochemical defects remain unknown. Here, we performed whole-exome sequencing (WES) on 14 suspected LSD cases to evaluate the feasibility of using WES for identifying causal mutations. By examining 2,157 candidate genes potentially associated with lysosomal function, we identified eight variants in five genes as candidate disease-causing variants in four individuals. These included both known and novel mutations. Variants were corroborated by targeted sequencing and, when possible, functional assays. In addition, we identified nonsense mutations in two individuals in genes that are not known to have lysosomal function. However, mutations in these genes could have resulted in phenotypes that were diagnosed as LSDs. This study demonstrates that WES can be used to identify causal mutations in suspected LSD cases. We also demonstrate cases where a confounding clinical phenotype may potentially reflect more than one lysosomal protein defect. © 2017 Wiley Periodicals, Inc.

Phenotypic correction of von Willebrand disease type 3 blood-derived endothelial cells with lentiviral vectors expressing von Willebrand factor

PubMed Central

De Meyer, Simon F.; Vanhoorelbeke, Karen; Chuah, Marinee K.; Pareyn, Inge; Gillijns, Veerle; Hebbel, Robert P.; Collen, Désiré; Deckmyn, Hans; VandenDriessche, Thierry

2006-01-01

Von Willebrand disease (VWD) is an inherited bleeding disorder, caused by quantitative (type 1 and 3) or qualitative (type 2) defects in von Willebrand factor (VWF). Gene therapy is an appealing strategy for treatment of VWD because it is caused by a single gene defect and because VWF is secreted into the circulation, obviating the need for targeting specific organs or tissues. However, development of gene therapy for VWD has been hampered by the considerable length of the VWF cDNA (8.4 kb [kilobase]) and the inherent complexity of the VWF protein that requires extensive posttranslational processing. In this study, a gene-based approach for VWD was developed using lentiviral transduction of blood-outgrowth endothelial cells (BOECs) to express functional VWF. A lentiviral vector encoding complete human VWF was used to transduce BOECs isolated from type 3 VWD dogs resulting in high-transduction efficiencies (95.6% ± 2.2%). Transduced VWD BOECs efficiently expressed functional vector-encoded VWF (4.6 ± 0.4 U/24 hour per 106 cells), with normal binding to GPIbα and collagen and synthesis of a broad range of multimers resulting in phenotypic correction of these cells. These results indicate for the first time that gene therapy of type 3 VWD is feasible and that BOECs are attractive target cells for this purpose. PMID:16478886

Embryonic defence mechanisms against glucose-dependent oxidative stress require enhanced expression of Alx3 to prevent malformations during diabetic pregnancy.

PubMed

García-Sanz, Patricia; Mirasierra, Mercedes; Moratalla, Rosario; Vallejo, Mario

2017-03-24

Oxidative stress constitutes a major cause for increased risk of congenital malformations associated to severe hyperglycaemia during pregnancy. Mutations in the gene encoding the transcription factor ALX3 cause congenital craniofacial and neural tube defects. Since oxidative stress and lack of ALX3 favour excessive embryonic apoptosis, we investigated whether ALX3-deficiency further increases the risk of embryonic damage during gestational hyperglycaemia in mice. We found that congenital malformations associated to ALX3-deficiency are enhanced in diabetic pregnancies. Increased expression of genes encoding oxidative stress-scavenging enzymes in embryos from diabetic mothers was blunted in the absence of ALX3, leading to increased oxidative stress. Levels of ALX3 increased in response to glucose, but ALX3 did not activate oxidative stress defence genes directly. Instead, ALX3 stimulated the transcription of Foxo1, a master regulator of oxidative stress-scavenging genes, by binding to a newly identified binding site located in the Foxo1 promoter. Our data identify ALX3 as an important component of the defence mechanisms against the occurrence of developmental malformations during diabetic gestations, stimulating the expression of oxidative stress-scavenging genes in a glucose-dependent manner via Foxo1 activation. Thus, ALX3 deficiency provides a novel molecular mechanism for developmental defects arising from maternal hyperglycaemia.

Myopia and Late-Onset Progressive Cone Dystrophy Associate to LVAVA/MVAVA Exon 3 Interchange Haplotypes of Opsin Genes on Chromosome X.

PubMed

Orosz, Orsolya; Rajta, István; Vajas, Attila; Takács, Lili; Csutak, Adrienne; Fodor, Mariann; Kolozsvári, Bence; Resch, Miklós; Sényi, Katalin; Lesch, Balázs; Szabó, Viktória; Berta, András; Balogh, István; Losonczy, Gergely

2017-03-01

Rare interchange haplotypes in exon 3 of the OPN1LW and OPN1MW opsin genes cause X-linked myopia, color vision defect, and cone dysfunction. The severity of the disease varies on a broad scale from nonsyndromic high myopia to blue cone monochromatism. Here, we describe a new genotype-phenotype correlation attributed to rare exon 3 interchange haplotypes simultaneously present in the long- and middle-wavelength sensitive opsin genes (L- and M-opsin genes). A multigenerational family with X-linked high myopia and cone dystrophy was investigated. Affected male patients had infantile onset myopia with normal visual acuity and color vision until their forties. Visual acuity decreased thereafter, along with the development of severe protan and deutan color vision defects. A mild decrease in electroretinography response of cone photoreceptors was detected in childhood, which further deteriorated in middle-aged patients. Rods were also affected, however, to a lesser extent than cones. Clinical exome sequencing identified the LVAVA and MVAVA toxic haplotypes in the OPN1LW and OPN1MW opsin genes, respectively. Here, we show that LVAVA haplotype of the OPN1LW gene and MVAVA haplotype of the OPN1MW gene cause apparently nonsyndromic high myopia in young patients but lead to progressive cone-rod dystrophy with deuteranopia and protanopia in middle-aged patients corresponding to a previously unknown disease course. To the best of our knowledge, this is the first report on the joint effect of these toxic haplotypes in the two opsin genes on chromosome X.

Genome-wide screen uncovers novel pathways for tRNA processing and nuclear-cytoplasmic dynamics.

PubMed

Wu, Jingyan; Bao, Alicia; Chatterjee, Kunal; Wan, Yao; Hopper, Anita K

2015-12-15

Transfer ribonucleic acids (tRNAs) are essential for protein synthesis. However, key gene products involved in tRNA biogenesis and subcellular movement remain to be discovered. We conducted the first comprehensive unbiased analysis of the role of nearly an entire proteome in tRNA biology and describe 162 novel and 12 previously known Saccharomyces cerevisiae gene products that function in tRNA processing, turnover, and subcellular movement. tRNA nuclear export is of particular interest because it is essential, but the known tRNA exporters (Los1 [exportin-t] and Msn5 [exportin-5]) are unessential. We report that mutations of CRM1 (Exportin-1), MEX67/MTR2 (TAP/p15), and five nucleoporins cause accumulation of unspliced tRNA, a hallmark of defective tRNA nuclear export. CRM1 mutation genetically interacts with los1Δ and causes altered tRNA nuclear-cytoplasmic distribution. The data implicate roles for the protein and mRNA nuclear export machineries in tRNA nuclear export. Mutations of genes encoding actin cytoskeleton components and mitochondrial outer membrane proteins also cause accumulation of unspliced tRNA, likely due to defective splicing on mitochondria. Additional gene products, such as chromatin modification enzymes, have unanticipated effects on pre-tRNA end processing. Thus, this genome-wide screen uncovered putative novel pathways for tRNA nuclear export and extensive links between tRNA biology and other aspects of cell physiology. © 2015 Wu et al.; Published by Cold Spring Harbor Laboratory Press.

Genome-wide screen uncovers novel pathways for tRNA processing and nuclear–cytoplasmic dynamics

PubMed Central

Wu, Jingyan; Bao, Alicia; Chatterjee, Kunal; Wan, Yao; Hopper, Anita K.

2015-01-01

Transfer ribonucleic acids (tRNAs) are essential for protein synthesis. However, key gene products involved in tRNA biogenesis and subcellular movement remain to be discovered. We conducted the first comprehensive unbiased analysis of the role of nearly an entire proteome in tRNA biology and describe 162 novel and 12 previously known Saccharomyces cerevisiae gene products that function in tRNA processing, turnover, and subcellular movement. tRNA nuclear export is of particular interest because it is essential, but the known tRNA exporters (Los1 [exportin-t] and Msn5 [exportin-5]) are unessential. We report that mutations of CRM1 (Exportin-1), MEX67/MTR2 (TAP/p15), and five nucleoporins cause accumulation of unspliced tRNA, a hallmark of defective tRNA nuclear export. CRM1 mutation genetically interacts with los1Δ and causes altered tRNA nuclear–cytoplasmic distribution. The data implicate roles for the protein and mRNA nuclear export machineries in tRNA nuclear export. Mutations of genes encoding actin cytoskeleton components and mitochondrial outer membrane proteins also cause accumulation of unspliced tRNA, likely due to defective splicing on mitochondria. Additional gene products, such as chromatin modification enzymes, have unanticipated effects on pre-tRNA end processing. Thus, this genome-wide screen uncovered putative novel pathways for tRNA nuclear export and extensive links between tRNA biology and other aspects of cell physiology. PMID:26680305

Short stature caused by isolated SHOX gene haploinsufficiency: update on the diagnosis and treatment.

PubMed

Jorge, Alexander A L; Funari, Mariana Fa; Nishi, Mirian Y; Mendonca, Berenice B

2010-12-01

Heterozygous SHOX defects are observed in about 50 to 90% of patients with Leri-Weill dyschondrosteosis (LWD), a common dominant inherited skeletal dysplasia; and in 2 to 15% of children with idiopathic short stature (ISS), indicating that SHOX defects are the most important monogenetic cause of short stature. In addition, children selected by disproportionate idiopathic short stature had a higher frequency of SHOX mutations (22%). A careful clinical evaluation of family members with short stature is recommended since it usually revealed LWD patients in families first classified as having ISS or familial short stature. SHOX-molecular analysis is indicated in families with LWD and ISS children with disproportionate short stature. Treatment with recombinant human growth hormone is considered an accepted approach to treat short stature associated with isolated SHOX defect. Here we review clinical, molecular and therapeutic aspects of SHOX haploinsufficiency.

Germline hypomorphic CARD11 mutations in severe atopic disease

PubMed Central

Ma, Chi A; Stinson, Jeffrey R; Zhang, Yuan; Abbott, Jordan K; Weinreich, Michael A; Hauk, Pia J; Reynolds, Paul R; Lyons, Jonathan J; Nelson, Celeste G; Ruffo, Elisa; Dorjbal, Batsukh; Glauzy, Salomé; Yamakawa, Natsuko; Arjunaraja, Swadhinya; Voss, Kelsey; Stoddard, Jennifer; Niemela, Julie; Zhang, Yu; Rosenzweig, Sergio D; McElwee, Joshua J; DiMaggio, Thomas; Matthews, Helen F; Jones, Nina; Stone, Kelly D; Palma, Alejandro; Oleastro, Matías; Prieto, Emma; Bernasconi, Andrea R; Dubra, Geronimo; Danielian, Silvia; Zaiat, Jonathan; Marti, Marcelo A; Kim, Brian; Cooper, Megan A; Romberg, Neil D; Meffre, Eric; Gelfand, Erwin W; Snow, Andrew L; Milner, Joshua D

2017-01-01

Few monogenic causes for severe manifestations of common allergic diseases have been identified. Via next generation sequencing on a cohort of patients with severe atopic dermatitis, some with comorbid infections, we found 8 individuals from 4 families with novel heterozygous mutations in CARD11, a scaffolding protein involved in lymphocyte receptor signaling. Disease improved over time in most patients. Transfection of mutant expression constructs into T cell lines demonstrated both loss of function and dominant interfering activity upon antigen receptor-induced NF-κB and mTORC1 activation. Patient T-cells had similar defects, as well as diminished IFN-γ cytokine production. The mTORC1 and IFN-γ production defects could be partially rescued by supplementing with glutamine, which requires CARD11 for import into T cells. Our findings indicate a single hypomorphic gene mutation in CARD11 can cause potentially correctable cellular defects that lead to atopic dermatitis. PMID:28628108

V-ATPase-dependent luminal acidification is required for endocytic recycling of a yeast cell wall stress sensor, Wsc1p

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ueno, Kazuma; Saito, Mayu; Nagashima, Makiko

Highlights: •A targeted genome screen identified 5 gene groups affecting Wsc1p recycling. •V-ATPase-dependent luminal acidification is required for Wsc1p recycling. •Activity of V-ATPase might be required for cargo recognition by the retromer complex. -- Abstract: Wsc1p is a major cell wall sensor protein localized at the polarized cell surface. The localization of Wsc1p is maintained by endocytosis and recycling from endosomes back to the cell surface, but changes to the vacuole when cells are subjected to heat stress. Exploiting this unique property of Wsc1p, we screened for yeast single-gene deletion mutants exhibiting defects in Wsc1p trafficking. By expressing 3GFP-tagged Wsc1pmore » in mutants with deleted genes whose function is related to intracellular trafficking, we identified 5 gene groups affecting Wsc1p trafficking, impaired respectively in endocytic internalization, multivesicular body sorting, the GARP complex, endosomal maturation/vacuolar fusion, and V-ATPase. Interestingly, deletion of the VPH1 gene, encoding the V{sub o} subunit of vacuolar-type H{sup +}-ATPase (V-ATPase), led to mis-localization of Wsc1p from the plasma membrane to the vacuole. In addition, disruption of other V-ATPase subunits (vma mutants) also caused defects of Wsc1p trafficking and vacuolar acidification similar to those seen in the vph1Δ mutant. Moreover, we found that deletion of the VPS26 gene, encoding a subunit of the retromer complex, also caused a defect in Wsc1p recycling and mis-localization of Wsc1p to the vacuole. These findings clarified the previously unidentified Wsc1p recycling pathway and requirement of V-ATPase-dependent luminal acidification for Wsc1p recycling.« less

Familial Hypercholesterolaemia

PubMed Central

Marais, A David

2004-01-01

Familial hypercholesterolaemia (FH), defined as the heritable occurrence of severe hypercholesterolaemia with cholesterol deposits in tendons and premature heart disease, is caused by at least four genes in sterol and lipoprotein pathways and displays varying gene-dose effects. The genes are the low-density lipoprotein (LDL) receptor, apolipoprotein (apo) B, proprotein convertase subtilisin/kexin 9, and the autosomal recessive hypercholesterolaemia (ARH) adaptor protein. All of these disorders have in common defective clearance of LDL within a complex system of lipid and lipoprotein metabolism and regulation. Normal cellular cholesterol and lipoprotein metabolism is reviewed before describing the disorders, their metabolic derangements and their clinical effects. FH is classified as two simplified phenotypes of disease according to the severity of the metabolic derangement. The dominantly inherited heterozygous phenotype comprises defects in the LDL receptor, apoB100, and neural apoptosis regulatory cleavage protein. The homozygous phenotype is co-dominant in defects of the LDL receptor, and occurs also as the ARH of adapter protein mutations. Defective binding of apoB100 does not result in a significant gene dose effect, but enhances the severity of heterozygotes for LDL receptor mutations. The genetic diagnosis of FH has provided greater accuracy in definition and detection of disease and exposes information about migration of populations. All of these disorders pose a high risk of atherosclerosis, especially in the homozygous phenotype. Studies of influences on the phenotype and responses to treatment are also discussed in the context of the metabolic derangements. PMID:18516203

SDN-1/syndecan regulates growth factor signaling in distal tip cell migrations in C. elegans.

PubMed

Schwabiuk, Megan; Coudiere, Ludivine; Merz, David C

2009-10-01

Mutations in the sdn-1/syndecan gene act as genetic enhancers of the ventral-to-dorsal distal tip cell (DTC) migration defects caused by a weak allele of the netrin receptor gene unc-5. The sdn-1(ev697) allele was identified in a genetic screen for enhancers of unc-5 DTC migration defects, and carried a nonsense mutation predicted to truncate the SDN-1 protein prior to the transmembrane domain. The enhancement of unc-5 caused by an sdn-1 mutation was rescued by expression of wild-type sdn-1 in the hypodermis or nervous system rather than the DTCs, indicating a cell non-autonomous function of sdn-1. The enhancement was also partially reversed by mutations in the egl-17/FGF or egl-20/Wnt genes, suggesting that sdn-1 affects UNC-5 function through a mis-regulation of signaling in growth factor pathways. egl-20 reporter constructs exhibited increased and mis-localized EGL-20 distribution in sdn-1 mutants compared to wild-type animals. Finally, using loss of function mutations, we show that egl-17/Fgf and egl-20/Wnt are partially redundant in regulating the migration pattern of the posterior DTC, as double mutants exhibit significant frequencies of defects in migration phases along both the anteroposterior and dorsoventral axes. Together these results suggest that SDN-1 affects UNC-5 function by regulating the proper extracellular distribution of growth factors.

Ift25 is not a cystic kidney disease gene but is required for early steps of kidney development.

PubMed

Desai, Paurav B; San Agustin, Jovenal T; Stuck, Michael W; Jonassen, Julie A; Bates, Carlton M; Pazour, Gregory J

2018-06-01

Eukaryotic cilia are assembled by intraflagellar transport (IFT) where large protein complexes called IFT particles move ciliary components from the cell body to the cilium. Defects in most IFT particle proteins disrupt ciliary assembly and cause mid gestational lethality in the mouse. IFT25 and IFT27 are unusual components of IFT-B in that they are not required for ciliary assembly and mutant mice survive to term. The mutants die shortly after birth with numerous organ defects including duplex kidneys. Completely duplex kidneys result from defects in ureteric bud formation at the earliest steps of metanephric kidney development. Ureteric bud initiation is a highly regulated process involving reciprocal signaling between the ureteric epithelium and the overlying metanephric mesenchyme with regulation by the peri-Wolffian duct stroma. The finding of duplex kidney in Ift25 and Ift27 mutants suggests functions for these genes in regulation of ureteric bud initiation. Typically the deletion of IFT genes in the kidney causes rapid cyst growth in the early postnatal period. In contrast, the loss of Ift25 results in smaller kidneys, which show only mild tubule dilations that become apparent in adulthood. The smaller kidneys appear to result from reduced branching in the developing metanephric kidney. This work indicates that IFT25 and IFT27 are important players in the early development of the kidney and suggest that duplex kidney is part of the ciliopathy spectrum. Copyright © 2018 Elsevier B.V. All rights reserved.

Essential functions of the Williams-Beuren syndrome-associated TFII-I genes in embryonic development.

PubMed

Enkhmandakh, Badam; Makeyev, Aleksandr V; Erdenechimeg, Lkhamsuren; Ruddle, Frank H; Chimge, Nyam-Osor; Tussie-Luna, Maria Isabel; Roy, Ananda L; Bayarsaihan, Dashzeveg

2009-01-06

GTF2I and GTF2IRD1 encoding the multifunctional transcription factors TFII-I and BEN are clustered at the 7q11.23 region hemizygously deleted in Williams-Beuren syndrome (WBS), a complex multisystemic neurodevelopmental disorder. Although the biochemical properties of TFII-I family transcription factors have been studied in depth, little is known about the specialized contributions of these factors in pathways required for proper embryonic development. Here, we show that homozygous loss of either Gtf2ird1 or Gtf2i function results in multiple phenotypic manifestations, including embryonic lethality; brain hemorrhage; and vasculogenic, craniofacial, and neural tube defects in mice. Further analyses suggest that embryonic lethality may be attributable to defects in yolk sac vasculogenesis and angiogenesis. Microarray data indicate that the Gtf2ird1 homozygous phenotype is mainly caused by an impairment of the genes involved in the TGFbetaRII/Alk1/Smad5 signal transduction pathway. The effect of Gtf2i inactivation on this pathway is less prominent, but downregulation of the endothelial growth factor receptor-2 gene, resulting in the deterioration of vascular signaling, most likely exacerbates the severity of the Gtf2i mutant phenotype. A subset of Gtf2ird1 and Gtf2i heterozygotes displayed microcephaly, retarded growth, and skeletal and craniofacial defects, therefore showing that haploinsufficiency of TFII-I proteins causes various developmental anomalies that are often associated with WBS.

CRISPR-Cas9 Corrects Mutation in Immune Disorder, Suggesting New Therapeutic Approach | FNLCR Staging

Cancer.gov

Gene editing using the powerful new CRISPR-Cas9 system is showing promise as a tool for developing potential treatments for inherited diseases, particularly for those caused by single genetic defects. Examples of these diseases are cystic fibrosis, m

The Caenorhabditis Elegans Unc-31 Gene Affects Multiple Nervous System-Controlled Functions

PubMed Central

Avery, L.; Bargmann, C. I.; Horvitz, H. R.

1993-01-01

We have devised a method for selecting Caenorhabditis elegans mutants that execute feeding motions in the absence of food. One mutation isolated in this way is an allele of the gene unc-31, first discovered by S. Brenner in 1974, because of its effects on locomotion. We find that strong unc-31 mutations cause defects in four functions controlled by the nervous system. Mutant worms are lethargic, feed constitutively, are defective in egg-laying and produce dauer larvae that fail to recover. We discuss two extreme models to explain this pleiotropy: either unc-31 affects one or a few neurons that coordinately control several different functions, or it affects many neurons that independently control different functions. PMID:8325482

Mitochondrial Respiratory Defect Causes Dysfunctional Lactate Turnover via AMP-activated Protein Kinase Activation in Human-induced Pluripotent Stem Cell-derived Hepatocytes*

PubMed Central

Im, Ilkyun; Jang, Mi-jin; Park, Seung Ju; Lee, Sang-Hee; Choi, Jin-Ho; Yoo, Han-Wook; Kim, Seyun; Han, Yong-Mahn

2015-01-01

A defective mitochondrial respiratory chain complex (DMRC) causes various metabolic disorders in humans. However, the pathophysiology of DMRC in the liver remains unclear. To understand DMRC pathophysiology in vitro, DMRC-induced pluripotent stem cells were generated from dermal fibroblasts of a DMRC patient who had a homoplasmic mutation (m.3398T→C) in the mitochondrion-encoded NADH dehydrogenase 1 (MTND1) gene and that differentiated into hepatocytes (DMRC hepatocytes) in vitro. DMRC hepatocytes showed abnormalities in mitochondrial characteristics, the NAD+/NADH ratio, the glycogen storage level, the lactate turnover rate, and AMPK activity. Intriguingly, low glycogen storage and transcription of lactate turnover-related genes in DMRC hepatocytes were recovered by inhibition of AMPK activity. Thus, AMPK activation led to metabolic changes in terms of glycogen storage and lactate turnover in DMRC hepatocytes. These data demonstrate for the first time that energy depletion may lead to lactic acidosis in the DMRC patient by reduction of lactate uptake via AMPK in liver. PMID:26491018

The Aspergillus nidulans npkA gene encodes a Cdc2-related kinase that genetically interacts with the UvsBATR kinase.

PubMed Central

Fagundes, Marcia R V Z Kress; Lima, Joel Fernandes; Savoldi, Marcela; Malavazi, Iran; Larson, Roy E; Goldman, Maria H S; Goldman, Gustavo H

2004-01-01

The DNA damage response is a protective mechanism that ensures the maintenance of genomic integrity. We have used Aspergillus nidulans as a model system to characterize the DNA damage response caused by the antitopoisomerase I drug, camptothecin. We report the molecular characterization of a p34Cdc2-related gene, npkA, from A. nidulans. The npkA gene is transcriptionally induced by camptothecin and other DNA-damaging agents, and its induction in the presence of camptothecin is dependent on the uvsBATR gene. There were no growth defects, changes in developmental patterns, increased sensitivity to DNA-damaging agents, or effects on septation or growth rate in the A. nidulans npkA deletion strain. However, the DeltanpkA mutation can partially suppress HU sensitivity caused by the DeltauvsBATR and uvsD153ATRIP checkpoint mutations. We demonstrated that the A. nidulans uvsBATR gene is involved in DNA replication and the intra-S-phase checkpoints and that the DeltanpkA mutation can suppress its intra-S-phase checkpoint deficiency. There is a defect in both the intra-S-phase and DNA replication checkpoints due to the npkA inactivation when DNA replication is slowed at 6 mm HU. Our results suggest that the npkA gene plays a role in cell cycle progression during S-phase as well as in a DNA damage signal transduction pathway in A. nidulans. PMID:15342504

Mono-2-ethylhexyl phthalate disrupts neurulation and modifies the embryonic redox environment and gene expression

PubMed Central

Sant, Karilyn E.; Dolinoy, Dana C.; Jilek, Joseph L.; Sartor, Maureen A.; Harris, Craig

2016-01-01

Mono-2-ethylhexl phthalate (MEHP) is the primary metabolite of di-2-ethylhexyl phthalate (DEHP), a ubiquitous contaminant in plastics. This study sought to determine how structural defects caused by MEHP in mouse whole embryo culture were related to temporal and spatial patterns of redox state and gene expression. MEHP reduced morphology scores along with increased incidence of neural tube defects. Glutathione (GSH) and cysteine (Cys) concentrations fluctuated spatially and temporally in embryo (EMB) and visceral yolk sac (VYS) across the 24h culture. Redox potentials (Eh) for GSSG/GSH were increased by MEHP in EMB (12h) but not in VYS. CySS/CyS Eh in EMB and VYS were significantly increased at 3h and 24h, respectively. Gene expression at 6h showed that MEHP induced selective alterations in EMB and VYS for oxidative phosphorylation and energy metabolism pathways. Overall, MEHP affects neurulation, alters Eh, and spatially alters the expression of metabolic genes in the early organogenesis-stage mouse conceptus. PMID:27167697

Phenotypic consequences of gene disruption by a balanced de novo translocation involving SLC6A1 and NAA15.

PubMed

Pesz, Karolina; Pienkowski, Victor Murcia; Pollak, Agnieszka; Gasperowicz, Piotr; Sykulski, Maciej; Kosińska, Joanna; Kiszko, Magdalena; Krzykwa, Bogusława; Bartnik-Głaska, Magdalena; Nowakowska, Beata; Rydzanicz, Małgorzata; Sasiadek, Maria Małgorzata; Płoski, Rafał

2018-04-03

Mapping of de novo balanced chromosomal translocations (BCTs) in patients with sporadic poorly characterized disease(s) is an unbiased method of finding candidate gene(s) responsible for the observed symptoms. We present a paediatric patient suffering from epilepsy, developmental delay (DD) and atrial septal defect IIº (ASD) requiring surgery. Karyotyping indicated an apparently balanced de novo reciprocal translocation 46,XX,t(3;4)(p25.3;q31.1), whereas aCGH did not reveal any copy number changes. Using shallow mate-pair whole genome sequencing and direct Sanger sequencing of breakpoint regions we found that translocation disrupted SLC6A1 and NAA15 genes. Our results confirm two previous reports indicating that loss of function of a single allele of SLC6A1 causes epilepsy. In addition, we extend existing evidence that disruption of NAA15 is associated with DD and with congenital heart defects. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

A SMN-Dependent U12 Splicing Event Essential for Motor Circuit Function

PubMed Central

Lotti, Francesco; Imlach, Wendy L.; Saieva, Luciano; Beck, Erin S.; Hao, Le T.; Li, Darrick K.; Jiao, Wei; Mentis, George Z.; Beattie, Christine E.; McCabe, Brian D.; Pellizzoni, Livio

2012-01-01

SUMMARY Spinal muscular atrophy (SMA) is a motor neuron disease caused by deficiency of the ubiquitous survival motor neuron (SMN) protein. To define the mechanisms of selective neuronal dysfunction in SMA, we investigated the role of SMN-dependent U12 splicing events in the regulation of motor circuit activity. We show that SMN deficiency perturbs splicing and decreases the expression of a subset of U12 intron-containing genes in mammalian cells and Drosophila larvae. Analysis of these SMN target genes identifies Stasimon as a novel protein required for motor circuit function. Restoration of Stasimon expression in the motor circuit corrects defects in neuromuscular junction transmission and muscle growth in Drosophila SMN mutants and aberrant motor neuron development in SMN-deficient zebrafish. These findings directly link defective splicing of critical neuronal genes induced by SMN deficiency to motor circuit dysfunction, establishing a molecular framework for the selective pathology of SMA. PMID:23063131

[Alternative splicing regulation: implications in cancer diagnosis and treatment].

PubMed

Martínez-Montiel, Nancy; Rosas-Murrieta, Nora; Martínez-Contreras, Rebeca

2015-04-08

The accurate expression of the genetic information is regulated by processes like mRNA splicing, proposed after the discoveries of Phil Sharp and Richard Roberts, who demonstrated the existence of intronic sequences, present in almost every structural eukaryotic gene, which should be precisely removed. This intron removal is called "splicing", which generates different proteins from a single mRNA, with different or even antagonistic functions. We currently know that alternative splicing is the most important source of protein diversity, given that 70% of the human genes undergo splicing and that mutations causing defects in this process could originate up to 50% of genetic diseases, including cancer. When these defects occur in genes involved in cell adhesion, proliferation and cell cycle regulation, there is an impact on cancer progression, rising the opportunity to diagnose and treat some types of cancer according to a particular splicing profile. Copyright © 2013 Elsevier España, S.L.U. All rights reserved.

Xenopus as a Model Organism for Birth Defects – Congenital Heart Disease and Heterotaxy

PubMed Central

Duncan, Anna R.; Khokha, Mustafa K.

2016-01-01

Congenital heart disease is the leading cause of birth defects, affecting 9 out of 1000 newborns each year. A particularly severe form of congenital heart disease is heterotaxy, a disorder of left-right development. Despite aggressive surgical management, patients with heterotaxy have poor survival rates and severe morbidity due to their complex congenital heart disease. Recent genetic analysis of affected patients has found novel candidate genes for heterotaxy although their underlying mechanisms remain unknown. In this review, we discuss the importance and challenges of birth defects research including high locus heterogeneity and few second alleles that make defining disease causality difficult. A powerful strategy moving forward is to analyze these candidate genes in a high-throughput human disease model. Xenopus is ideal for these studies. We present multiple examples demonstrating the power of Xenopus in discovery new biology from the analysis of candidate heterotaxy genes such as GALNT11, NEK2 and BCOR. These genes have diverse roles in embryos and have led to a greater understanding of complex signaling pathways and basic developmental biology. It is our hope that the mechanistic analysis of these candidate genes in Xenopus enabled by next generation sequencing of patients will provide clinicians with a greater understanding of patient pathophysiology allowing more precise and personalized medicine, to help them more effectively in the future. PMID:26910255

Advantages and pitfalls of an extended gene panel for investigating complex neurometabolic phenotypes.

PubMed

Reid, Emma S; Papandreou, Apostolos; Drury, Suzanne; Boustred, Christopher; Yue, Wyatt W; Wedatilake, Yehani; Beesley, Clare; Jacques, Thomas S; Anderson, Glenn; Abulhoul, Lara; Broomfield, Alex; Cleary, Maureen; Grunewald, Stephanie; Varadkar, Sophia M; Lench, Nick; Rahman, Shamima; Gissen, Paul; Clayton, Peter T; Mills, Philippa B

2016-11-01

Neurometabolic disorders are markedly heterogeneous, both clinically and genetically, and are characterized by variable neurological dysfunction accompanied by suggestive neuroimaging or biochemical abnormalities. Despite early specialist input, delays in diagnosis and appropriate treatment initiation are common. Next-generation sequencing approaches still have limitations but are already enabling earlier and more efficient diagnoses in these patients. We designed a gene panel targeting 614 genes causing inborn errors of metabolism and tested its diagnostic efficacy in a paediatric cohort of 30 undiagnosed patients presenting with variable neurometabolic phenotypes. Genetic defects that could, at least partially, explain observed phenotypes were identified in 53% of cases. Where biochemical abnormalities pointing towards a particular gene defect were present, our panel identified diagnoses in 89% of patients. Phenotypes attributable to defects in more than one gene were seen in 13% of cases. The ability of in silico tools, including structure-guided prediction programmes to characterize novel missense variants were also interrogated. Our study expands the genetic, clinical and biochemical phenotypes of well-characterized (POMGNT1, TPP1) and recently identified disorders (PGAP2, ACSF3, SERAC1, AFG3L2, DPYS). Overall, our panel was accurate and efficient, demonstrating good potential for applying similar approaches to clinically and biochemically diverse neurometabolic disease cohorts. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain.

Disrupted SOX10 function causes spongiform neurodegeneration in gray tremor mice

PubMed Central

Anderson, Sarah R.; Lee, Inyoul; Ebeling, Christine; Stephenson, Dennis A.; Schweitzer, Kelsey M.; Baxter, David; Moon, Tara M.; LaPierre, Sarah; Jaques, Benjamin; Silvius, Derek; Wegner, Michael; Hood, Leroy E.; Carlson, George; Gunn, Teresa M.

2014-01-01

Mice homozygous for the gray tremor (gt) mutation have a pleiotropic phenotype that includes pigmentation defects, megacolon, whole body tremors, sporadic seizures, hypo- and dysmyelination of the CNS and PNS, vacuolation of the CNS, and early death. Vacuolation similar to that caused by prions was originally reported to be transmissible, but subsequent studies showed the inherited disease was not infectious. The gt mutation mapped to distal mouse chromosome 15, to the same region as Sox10, which encodes a transcription factor with essential roles in neural crest survival and differentiation. As dominant mutations in mouse or human SOX10 cause white spotting and intestinal aganglionosis, we screened the Sox10 coding region for mutations in gt/gt DNA. An adenosine to guanine transversion was identified in exon 2 that changes a highly conserved glutamic acid residue in the SOX10 DNA binding domain to glycine. This mutant allele was not seen in wildtype mice, including the related GT/Le strain, and failed to complement a Sox10 null allele. Gene expression analysis revealed significant down-regulation of genes involved in myelin lipid biosynthesis pathways in gt/gt brains. Knockout mice for some of these genes develop CNS vacuolation and/or myelination defects, suggesting that their down-regulation may contribute to these phenotypes in gt mutants and could underlie the neurological phenotypes associated with Peripheral demyelinating neuropathy-Central dysmyelinating leukodystrophy-Waardenburg syndrome-Hirschsprung (PCWH) disease, caused by mutations in human SOX10. PMID:25399070

Planar Cell Polarity Pathway Genes and Risk for Spina Bifida

PubMed Central

Wen, Shu; Zhu, Huiping; Lu, Wei; Mitchell, Laura E.; Shaw, Gary M.; Lammer, Edward J.; Finnell, Richard H.

2009-01-01

Spina bifida, a neural tube closure defect (NTD) involving the posterior portion of what will ultimately give rise to the spinal cord, is one of the most common and serious birth defects. The etiology of spina bifida is thought to be multi-factorial and involve multiple interacting genes and environmental factors. The causes of this congenital malformation remain largely unknown. However, several candidate genes for spina bifida have been identified in lower vertebrates, including the planar cell polarity (PCP) genes. We used data from a case-control study conducted in California to evaluate the association between variation within several key PCP genes and the risk of spina bifida. The PCP genes included in this study were the human homologues of the Xenopus genes Flamingo, Strabismus, Prickle, Dishevelled and Scrib, two of the homologues of Xenopus Wnt genes, WNT5A and WNT11, and two of the homologues of Xenopus Frizzled, FZD3 and FZD6. None of the 172 SNPs that were evaluated were significantly associated with spina bifida in any racial/ethnic group after correction for multiple testing. However, several SNPs in the PRICKLE2 gene had unadjusted p value<0.01. In conclusion our results, though largely negative, suggest that the PRICKLE2 gene may potentially modify the risk of spina bifida and deserves further investigation. PMID:20101694

Splice-Site Mutations Cause Rrp6-Mediated Nuclear Retention of the Unspliced RNAs and Transcriptional Down-Regulation of the Splicing-Defective Genes

PubMed Central

Eberle, Andrea B.; Hessle, Viktoria; Helbig, Roger; Dantoft, Widad; Gimber, Niclas; Visa, Neus

2010-01-01

Background Eukaryotic cells have developed surveillance mechanisms to prevent the expression of aberrant transcripts. An early surveillance checkpoint acts at the transcription site and prevents the release of mRNAs that carry processing defects. The exosome subunit Rrp6 is required for this checkpoint in Saccharomyces cerevisiae, but it is not known whether Rrp6 also plays a role in mRNA surveillance in higher eukaryotes. Methodology/Principal Findings We have developed an in vivo system to study nuclear mRNA surveillance in Drosophila melanogaster. We have produced S2 cells that express a human β-globin gene with mutated splice sites in intron 2 (mut β-globin). The transcripts encoded by the mut β-globin gene are normally spliced at intron 1 but retain intron 2. The levels of the mut β-globin transcripts are much lower than those of wild type (wt) ß-globin mRNAs transcribed from the same promoter. We have compared the expression of the mut and wt β-globin genes to investigate the mechanisms that down-regulate the production of defective mRNAs. Both wt and mut β-globin transcripts are processed at the 3′, but the mut β-globin transcripts are less efficiently cleaved than the wt transcripts. Moreover, the mut β-globin transcripts are less efficiently released from the transcription site, as shown by FISH, and this defect is restored by depletion of Rrp6 by RNAi. Furthermore, transcription of the mut β-globin gene is significantly impaired as revealed by ChIP experiments that measure the association of the RNA polymerase II with the transcribed genes. We have also shown that the mut β-globin gene shows reduced levels of H3K4me3. Conclusions/Significance Our results show that there are at least two surveillance responses that operate cotranscriptionally in insect cells and probably in all metazoans. One response requires Rrp6 and results in the inefficient release of defective mRNAs from the transcription site. The other response acts at the transcription level and reduces the synthesis of the defective transcripts through a mechanism that involves histone modifications. PMID:20634951

De novo 14q24.2q24.3 microdeletion including IFT43 is associated with intellectual disability, skeletal anomalies, cardiac anomalies, and myopia.

PubMed

Stokman, Marijn F; Oud, Machteld M; van Binsbergen, Ellen; Slaats, Gisela G; Nicolaou, Nayia; Renkema, Kirsten Y; Nijman, Isaac J; Roepman, Ronald; Giles, Rachel H; Arts, Heleen H; Knoers, Nine V A M; van Haelst, Mieke M

2016-06-01

We report an 11-year-old girl with mild intellectual disability, skeletal anomalies, congenital heart defect, myopia, and facial dysmorphisms including an extra incisor, cup-shaped ears, and a preauricular skin tag. Array comparative genomic hybridization analysis identified a de novo 4.5-Mb microdeletion on chromosome 14q24.2q24.3. The deleted region and phenotype partially overlap with previously reported patients. Here, we provide an overview of the literature on 14q24 microdeletions and further delineate the associated phenotype. We performed exome sequencing to examine other causes for the phenotype and queried genes present in the 14q24.2q24.3 microdeletion that are associated with recessive disease for variants in the non-deleted allele. The deleted region contains 65 protein-coding genes, including the ciliary gene IFT43. Although Sanger and exome sequencing did not identify variants in the second IFT43 allele or in other IFT complex A-protein-encoding genes, immunocytochemistry showed increased accumulation of IFT-B proteins at the ciliary tip in patient-derived fibroblasts compared to control cells, demonstrating defective retrograde ciliary transport. This could suggest a ciliary defect in the pathogenesis of this disorder. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Genetic Control of Vulval Development in Caenorhabditis briggsae

PubMed Central

Sharanya, Devika; Thillainathan, Bavithra; Marri, Sujatha; Bojanala, Nagagireesh; Taylor, Jon; Flibotte, Stephane; Moerman, Donald G.; Waterston, Robert H.; Gupta, Bhagwati P.

2012-01-01

The nematode Caenorhabditis briggsae is an excellent model organism for the comparative analysis of gene function and developmental mechanisms. To study the evolutionary conservation and divergence of genetic pathways mediating vulva formation, we screened for mutations in C. briggsae that cause the egg-laying defective (Egl) phenotype. Here, we report the characterization of 13 genes, including three that are orthologs of Caenorhabditis elegans unc-84 (SUN domain), lin-39 (Dfd/Scr-related homeobox), and lin-11 (LIM homeobox). Based on the morphology and cell fate changes, the mutants were placed into four different categories. Class 1 animals have normal-looking vulva and vulva-uterine connections, indicating defects in other components of the egg-laying system. Class 2 animals frequently lack some or all of the vulval precursor cells (VPCs) due to defects in the migration of P-cell nuclei into the ventral hypodermal region. Class 3 animals show inappropriate fusion of VPCs to the hypodermal syncytium, leading to a reduced number of vulval progeny. Finally, class 4 animals exhibit abnormal vulval invagination and morphology. Interestingly, we did not find mutations that affect VPC induction and fates. Our work is the first study involving the characterization of genes in C. briggsae vulva formation, and it offers a basis for future investigations of these genes in C. elegans. PMID:23275885

New and emerging targeted therapies for cystic fibrosis

PubMed Central

Rowe, Steven M

2016-01-01

Cystic fibrosis (CF) is a monogenic autosomal recessive disorder that affects about 70 000 people worldwide. The clinical manifestations of the disease are caused by defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The discovery of the CFTR gene in 1989 has led to a sophisticated understanding of how thousands of mutations in the CFTR gene affect the structure and function of the CFTR protein. Much progress has been made over the past decade with the development of orally bioavailable small molecule drugs that target defective CFTR proteins caused by specific mutations. Furthermore, there is considerable optimism about the prospect of gene replacement or editing therapies to correct all mutations in cystic fibrosis. The recent approvals of ivacaftor and lumacaftor represent the genesis of a new era of precision medicine in the treatment of this condition. These drugs are having a positive impact on the lives of people with cystic fibrosis and are potentially disease modifying. This review provides an update on advances in our understanding of the structure and function of the CFTR, with a focus on state of the art targeted drugs that are in development. PMID:27030675

Human cytochromes P450 in health and disease

PubMed Central

Nebert, Daniel W.; Wikvall, Kjell; Miller, Walter L.

2013-01-01

There are 18 mammalian cytochrome P450 (CYP) families, which encode 57 genes in the human genome. CYP2, CYP3 and CYP4 families contain far more genes than the other 15 families; these three families are also the ones that are dramatically larger in rodent genomes. Most (if not all) genes in the CYP1, CYP2, CYP3 and CYP4 families encode enzymes involved in eicosanoid metabolism and are inducible by various environmental stimuli (i.e. diet, chemical inducers, drugs, pheromones, etc.), whereas the other 14 gene families often have only a single member, and are rarely if ever inducible or redundant. Although the CYP2 and CYP3 families can be regarded as largely redundant and promiscuous, mutations or other defects in one or more genes of the remaining 16 gene families are primarily the ones responsible for P450-specific diseases—confirming these genes are not superfluous or promiscuous but rather are more directly involved in critical life functions. P450-mediated diseases comprise those caused by: aberrant steroidogenesis; defects in fatty acid, cholesterol and bile acid pathways; vitamin D dysregulation and retinoid (as well as putative eicosanoid) dysregulation during fertilization, implantation, embryogenesis, foetogenesis and neonatal development. PMID:23297354

Potential treatments for genetic hearing loss in humans: current conundrums.

PubMed

Minoda, R; Miwa, T; Ise, M; Takeda, H

2015-08-01

Genetic defects are a major cause of hearing loss in newborns. Consequently, hearing loss has a profound negative impact on human daily living. Numerous causative genes for genetic hearing loss have been identified. However, presently, there are no truly curative treatments for this condition. There have been several recent reports on successful treatments in mice using embryonic gene therapy, neonatal gene therapy and neonatal antisense oligonucleotide therapy. Herein, we describe state-of-the-art research on genetic hearing loss treatment through gene therapy and discuss the obstacles to overcome in curative treatments of genetic hearing loss in humans.

Increased folding and channel activity of a rare cystic fibrosis mutant with CFTR modulators

PubMed Central

Grove, Diane E.; Houck, Scott A.

2011-01-01

Cystic fibrosis (CF) is a lethal recessive genetic disease caused by mutations in the CFTR gene. The gene product is a PKA-regulated anion channel that is important for fluid and electrolyte transport in the epithelia of lung, gut, and ducts of the pancreas and sweat glands. The most common CFTR mutation, ΔF508, causes a severe, but correctable, folding defect and gating abnormality, resulting in negligible CFTR function and disease. There are also a large number of rare CF-related mutations where disease is caused by CFTR misfolding. Yet the extent to which defective biogenesis of these CFTR mutants can be corrected is not clear. CFTRV232D is one such mutant that exhibits defective folding and trafficking. CFTRΔF508 misfolding is difficult to correct, but defective biogenesis of CFTRV232D is corrected to near wild-type levels by small-molecule folding correctors in development as CF therapeutics. To determine if CFTRV232D protein is competent as a Cl− channel, we utilized single-channel recordings from transfected human embryonic kidney (HEK-293) cells. After PKA stimulation, CFTRV232D channels were detected in patches with a unitary Cl− conductance indistinguishable from that of CFTR. Yet the frequency of detecting CFTRV232D channels was reduced to ∼20% of patches compared with 60% for CFTR. The folding corrector Corr-4a increased the CFTRV232D channel detection rate and activity to levels similar to CFTR. CFTRV232D-corrected channels were inhibited with CFTRinh-172 and stimulated fourfold by the CFTR channel potentiator VRT-532. These data suggest that CF patients with rare mutations that cause CFTR misfolding, such as CFTRV232D, may benefit from treatment with folding correctors and channel potentiators in development to restore CFTRΔF508 function. PMID:21642448

Noonan syndrome gain-of-function mutations in NRAS cause zebrafish gastrulation defects

PubMed Central

Runtuwene, Vincent; van Eekelen, Mark; Overvoorde, John; Rehmann, Holger; Yntema, Helger G.; Nillesen, Willy M.; van Haeringen, Arie; van der Burgt, Ineke; Burgering, Boudewijn; den Hertog, Jeroen

2011-01-01

SUMMARY Noonan syndrome is a relatively common developmental disorder that is characterized by reduced growth, wide-set eyes and congenital heart defects. Noonan syndrome is associated with dysregulation of the Ras–mitogen-activated-protein-kinase (MAPK) signaling pathway. Recently, two mutations in NRAS were reported to be associated with Noonan syndrome, T50I and G60E. Here, we report a mutation in NRAS, resulting in an I24N amino acid substitution, that we identified in an individual bearing typical Noonan syndrome features. The I24N mutation activates N-Ras, resulting in enhanced downstream signaling. Expression of N-Ras-I24N, N-Ras-G60E or the strongly activating mutant N-Ras-G12V, which we included as a positive control, results in developmental defects in zebrafish embryos, demonstrating that these activating N-Ras mutants are sufficient to induce developmental disorders. The defects in zebrafish embryos are reminiscent of symptoms in individuals with Noonan syndrome and phenocopy the defects that other Noonan-syndrome-associated genes induce in zebrafish embryos. MEK inhibition completely rescued the activated N-Ras-induced phenotypes, demonstrating that these defects are mediated exclusively by Ras-MAPK signaling. In conclusion, mutations in NRAS from individuals with Noonan syndrome activated N-Ras signaling and induced developmental defects in zebrafish embryos, indicating that activating mutations in NRAS cause Noonan syndrome. PMID:21263000

The type III secretion system is involved in the invasion and intracellular survival of Escherichia coli K1 in human brain microvascular endothelial cells.

PubMed

Yao, Yufeng; Xie, Yi; Perace, Donna; Zhong, Yi; Lu, Jie; Tao, Jing; Guo, Xiaokui; Kim, Kwang Sik

2009-11-01

Type III secretion systems (T3SSs) have been documented in many Gram-negative bacteria, including enterohemorrhagic Escherichia coli. We have previously shown the existence of a putative T3SS in meningitis-causing E. coli K1 strains, referred to as E. coli type III secretion 2 (ETT2). The sequence of ETT2 in meningitis-causing E. coli K1 strain EC10 (O7:K1) revealed that ETT2 comprises the epr, epa and eiv genes, but bears mutations, deletions and insertions. We constructed the EC10 mutants deleted of ETT2 or eivA gene, and their contributions to bacterial pathogenesis were evaluated in human brain microvascular endothelial cells (HBMECs). The deletion mutant of ETT2 exhibited defects in invasion and intracellular survival compared with the parental E. coli K1 strain EC10. The mutant deleted of eivA within ETT2 was also significantly defective in invasion and intracellular survival in HBMECs, and the defects of the eiv mutant were restored to the levels of the parent strain EC10 by transcomplementation. These findings suggest that ETT2 plays a role in the pathogenesis of E. coli K1 infection, including meningitis.

Mutations in MYB3R1 and MYB3R4 Cause Pleiotropic Developmental Defects and Preferential Down-Regulation of Multiple G2/M-Specific Genes in Arabidopsis1[C][W

PubMed Central

Haga, Nozomi; Kobayashi, Kosuke; Suzuki, Takamasa; Maeo, Kenichiro; Kubo, Minoru; Ohtani, Misato; Mitsuda, Nobutaka; Demura, Taku; Nakamura, Kenzo; Jürgens, Gerd; Ito, Masaki

2011-01-01

R1R2R3-Myb proteins represent an evolutionarily conserved class of Myb family proteins important for cell cycle regulation and differentiation in eukaryotic cells. In plants, this class of Myb proteins are believed to regulate the transcription of G2/M phase-specific genes by binding to common cis-elements, called mitosis-specific activator (MSA) elements. In Arabidopsis (Arabidopsis thaliana), MYB3R1 and MYB3R4 act as transcriptional activators and positively regulate cytokinesis by activating the transcription of KNOLLE, which encodes a cytokinesis-specific syntaxin. Here, we show that the double mutation myb3r1 myb3r4 causes pleiotropic developmental defects, some of which are due to deficiency of KNOLLE whereas other are not, suggesting that multiple target genes are involved. Consistently, microarray analysis of the double mutant revealed altered expression of many genes, among which G2/M-specific genes showed significant overrepresentation of the MSA motif and a strong tendency to be down-regulated by the double mutation. Our results demonstrate, on a genome-wide level, the importance of the MYB3R-MSA pathway for regulating G2/M-specific transcription. In addition, MYB3R1 and MYB3R4 may have diverse roles during plant development by regulating G2/M-specific genes with various functions as well as genes possibly unrelated to the cell cycle. PMID:21862669

The Human L1 Element Causes DNA Double-Strand Breaks in Breast Cancer

DTIC Science & Technology

2006-08-01

cancer is complex. However, defects in DNA repair genes in the double-strand break repair pathway are cancer predisposing. My lab has characterized...a new potentially important source of double-strand breaks (DSBs) in human cells and are interested in characterizing which DNA repair genes act on...this particular source of DNA damage. Selfish DNA accounts for 45% of the human genome. We have recently demonstrated that one particular selfish

The MARVEL domain protein Nce102 regulates actin organization and invasive growth of Candida albicans.

PubMed

Douglas, Lois M; Wang, Hong X; Konopka, James B

2013-11-26

Invasive growth of the fungal pathogen Candida albicans into tissues promotes disseminated infections in humans. The plasma membrane is essential for pathogenesis because this important barrier mediates morphogenesis and invasive growth, as well as secretion of virulence factors, cell wall synthesis, nutrient import, and other processes. Previous studies showed that the Sur7 tetraspan protein that localizes to MCC (membrane compartment occupied by Can1)/eisosome subdomains of the plasma membrane regulates a broad range of key functions, including cell wall synthesis, morphogenesis, and resistance to copper. Therefore, a distinct tetraspan protein found in MCC/eisosomes, Nce102, was investigated. Nce102 belongs to the MARVEL domain protein family, which is implicated in regulating membrane structure and function. Deletion of NCE102 did not cause the broad defects seen in sur7Δ cells. Instead, the nce102Δ mutant displayed a unique phenotype in that it was defective in forming hyphae and invading low concentrations of agar but could invade well in higher agar concentrations. This phenotype was likely due to a defect in actin organization that was observed by phalloidin staining. In support of this, the invasive growth defect of a bni1Δ mutant that mislocalizes actin due to lack of the Bni1 formin was also reversed at high agar concentrations. This suggests that a denser matrix provides a signal that compensates for the actin defects. The nce102Δ mutant displayed decreased virulence and formed abnormal hyphae in mice. These studies identify novel ways that Nce102 and the physical environment surrounding C. albicans regulate morphogenesis and pathogenesis. The plasma membrane promotes virulence of the human fungal pathogen Candida albicans by acting as a protective barrier around the cell and mediating dynamic activities, such as morphogenesis, cell wall synthesis, secretion of virulence factors, and nutrient uptake. To better understand how the plasma membrane contributes to virulence, we analyzed a set of eight genes encoding MARVEL family proteins that are predicted to function in membrane organization. Interestingly, deletion of one gene, NCE102, caused a strong defect in formation of invasive hyphal growth in vitro and decreased virulence in mice. The nce102Δ mutant cells showed defects in actin organization that underlie the morphogenesis defect, since mutation of a known regulator of actin organization caused a similar defect. These studies identify a novel way in which the plasma membrane regulates the actin cytoskeleton and contributes to pathogenesis.

Association of PKD2 (polycystin 2) mutations with left-right laterality defects.

PubMed

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.

Assessment of the role of copy-number variants in 150 patients with congenital heart defects.

PubMed

Derwińska, Katarzyna; Bartnik, Magdalena; Wiśniowiecka-Kowalnik, Barbara; Jagła, Mateusz; Rudziński, Andrzej; Pietrzyk, Jacek J; Kawalec, Wanda; Ziółkowska, Lidia; Kutkowska-Kaźmierczak, Anna; Gambin, Tomasz; Sykulski, Maciej; Shaw, Chad A; Gambin, Anna; Mazurczak, Tadeusz; Obersztyn, Ewa; Bocian, Ewa; Stankiewicz, Paweł

2012-01-01

Congenital heart defects are the most common group of major birth anomalies and one of the leading causes of infant deaths. Mendelian and chromosomal syndromes account for about 20% of congenital heart defects and in some cases are associated with other malformations, intellectual disability, and/or dysmorphic features. The remarkable conservation of genetic pathways regulating heart development in animals suggests that genetic factors can be responsible for a significantly higher percentage of cases. Assessment of the role of CNVs in the etiology of congenital heart defects using microarray studies. Genome-wide array comparative genomic hybridization, targeting genes known to play an important role in heart development or responsible for abnormal cardiac phenotype was used in the study on 150 patients. In addition, we have used multiplex ligation-dependent probe amplification specific for chromosome 22q11.2 region. We have identified 21 copy-number variants, including 13 known causative recurrent rearrangements (12 deletions 22q11.2 and one deletion 7q11.23), three potentially pathogenic duplications (5q14.2, 15q13.3, and 22q11.2), and five variants likely benign for cardiac anomalies. We suggest that abnormal copy-number of the ARRDC3 and KLF13 genes can be responsible for heart defects. Our study demonstrates that array comparative genomic hybridization enables detection of clinically significant chromosomal imbalances in patients with congenital heart defects.

Caenorhabditis elegans par2.1/mtssb-1 is essential for mitochondrial DNA replication and its defect causes comprehensive transcriptional alterations including a hypoxia response

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugimoto, Tomoko; Mori, Chihiro; Takanami, Takako

2008-01-01

DNA polymerase {gamma} and mtSSB are key components of the mtDNA replication machinery. To study the biological influences of defects in mtDNA replication, we used RNAi to deplete the gene for a putative mtSSB, par2.1, in Caenorhabditis elegans. In previous systematic RNAi screens, downregulation of this gene has not caused any clearly defective phenotypes. Here, we continuously fed a dsRNA targeting par2.1 to C. elegans over generations. Seventy-nine percent of F1 progeny produced 60-72 h after feeding grew to adulthood but were completely sterile, with an arrest of germline cell proliferation. Analyses of mtDNA copy number and cell cytology indicatedmore » that the sterile hermaphrodites had fewer mitochondria. These results indicated that par2.1 essentially functions for germline cell proliferation through mtDNA replication; we therefore termed it mtssb-1. Comprehensive transcriptional alterations including hypoxia response induction dependent on and independent of hif-1 function, occurred by RNAi depletion of mtssb-1. Treatment with ethidium bromide, which impairs mtDNA replication and transcription, caused similar transcriptional alterations. In addition, the frequency of apoptosis in the germline cells was reduced in fertile progeny with a partial RNAi effect. These suggest that RNAi depletion of C. elegans mtssb-1 is useful as a model system of mitochondrial dysfunction.« less

Mediator 1 contributes to enamel mineralization as a coactivator for Notch1 signaling and stimulates transcription of the alkaline phosphatase gene.

PubMed

Yoshizaki, Keigo; Hu, Lizhi; Nguyen, Thai; Sakai, Kiyoshi; Ishikawa, Masaki; Takahashi, Ichiro; Fukumoto, Satoshi; DenBesten, Pamela K; Bikle, Daniel D; Oda, Yuko; Yamada, Yoshihiko

2017-08-18

Tooth enamel is mineralized through the differentiation of multiple dental epithelia including ameloblasts and the stratum intermedium (SI), and this differentiation is controlled by several signaling pathways. Previously, we demonstrated that the transcriptional coactivator Mediator 1 (MED1) plays a critical role in enamel formation. For instance, conditional ablation of Med1 in dental epithelia causes functional changes in incisor-specific dental epithelial stem cells, resulting in mineralization defects in the adult incisors. However, the molecular mechanism by which Med1 deficiency causes these abnormalities is not clear. Here, we demonstrated that Med1 ablation causes early SI differentiation defects resulting in enamel hypoplasia of the Med1 -deficient molars. Med1 deletion prevented Notch1-mediated differentiation of the SI cells resulting in decreased alkaline phosphatase (ALPL), which is essential for mineralization. However, it does not affect the ability of ameloblasts to produce enamel matrix proteins. Using the dental epithelial SF2 cell line, we demonstrated that MED1 directly activates transcription of the Alpl gene through the stimulation of Notch1 signaling by forming a complex with cleaved Notch1-RBP-Jk on the Alpl promoter. These results suggest that MED1 may be essential for enamel matrix mineralization by serving as a coactivator for Notch1 signaling regulating transcription of the Alpl gene.

A novel form of ciliopathy underlies hyperphagia and obesity in Ankrd26 knockout mice.

PubMed

Acs, Peter; Bauer, Peter O; Mayer, Balazs; Bera, Tapan; Macallister, Rhonda; Mezey, Eva; Pastan, Ira

2015-01-01

Human ciliopathies are genetic disorders caused by mutations in genes responsible for the formation and function of primary cilia. Some are associated with hyperphagia and obesity (e.g., Bardet-Biedl Syndrome, Alström Syndrome), but the mechanisms underlying these problems are not fully understood. The human gene ANKRD26 is located on 10p12, a locus that is associated with some forms of hereditary obesity. Previously, we reported that disruption of this gene causes hyperphagia, obesity and gigantism in mice. In the present study, we looked for the mechanisms that induce hyperphagia in the Ankrd26-/- mice and found defects in primary cilia in regions of the central nervous system that control appetite and energy homeostasis.

Pleiotropic Regulation of Virulence Genes in Streptococcus mutans by the Conserved Small Protein SprV.

PubMed

Shankar, Manoharan; Hossain, Mohammad S; Biswas, Indranil

2017-04-15

Streptococcus mutans , an oral pathogen associated with dental caries, colonizes tooth surfaces as polymicrobial biofilms known as dental plaque. S. mutans expresses several virulence factors that allow the organism to tolerate environmental fluctuations and compete with other microorganisms. We recently identified a small hypothetical protein (90 amino acids) essential for the normal growth of the bacterium. Inactivation of the gene, SMU.2137, encoding this protein caused a significant growth defect and loss of various virulence-associated functions. An S. mutans strain lacking this gene was more sensitive to acid, temperature, osmotic, oxidative, and DNA damage-inducing stresses. In addition, we observed an altered protein profile and defects in biofilm formation, bacteriocin production, and natural competence development, possibly due to the fitness defect associated with SMU.2137 deletion. Transcriptome sequencing revealed that nearly 20% of the S. mutans genes were differentially expressed upon SMU.2137 deletion, thereby suggesting a pleiotropic effect. Therefore, we have renamed this hitherto uncharacterized gene as sprV ( s treptococcal p leiotropic r egulator of v irulence). The transcript levels of several relevant genes in the sprV mutant corroborated the phenotypes observed upon sprV deletion. Owing to its highly conserved nature, inactivation of the sprV ortholog in Streptococcus gordonii also resulted in poor growth and defective UV tolerance and competence development as in the case of S. mutans Our experiments suggest that SprV is functionally distinct from its homologs identified by structure and sequence homology. Nonetheless, our current work is aimed at understanding the importance of SprV in the S. mutans biology. IMPORTANCE Streptococcus mutans employs several virulence factors and stress resistance mechanisms to colonize tooth surfaces and cause dental caries. Bacterial pathogenesis is generally controlled by regulators of fitness that are critical for successful disease establishment. Sometimes these regulators, which are potential targets for antimicrobials, are lost in the genomic context due to the lack of annotated homologs. This work outlines the regulatory impact of a small, highly conserved hypothetical protein, SprV, encoded by S. mutans We show that SprV affects the transcript levels of various virulence factors required for normal growth, biofilm formation, stress tolerance, genetic competence, and bacteriocin production. Copyright © 2017 American Society for Microbiology.

Pleiotropic Regulation of Virulence Genes in Streptococcus mutans by the Conserved Small Protein SprV

PubMed Central

Shankar, Manoharan; Hossain, Mohammad S.

2017-01-01

ABSTRACT Streptococcus mutans, an oral pathogen associated with dental caries, colonizes tooth surfaces as polymicrobial biofilms known as dental plaque. S. mutans expresses several virulence factors that allow the organism to tolerate environmental fluctuations and compete with other microorganisms. We recently identified a small hypothetical protein (90 amino acids) essential for the normal growth of the bacterium. Inactivation of the gene, SMU.2137, encoding this protein caused a significant growth defect and loss of various virulence-associated functions. An S. mutans strain lacking this gene was more sensitive to acid, temperature, osmotic, oxidative, and DNA damage-inducing stresses. In addition, we observed an altered protein profile and defects in biofilm formation, bacteriocin production, and natural competence development, possibly due to the fitness defect associated with SMU.2137 deletion. Transcriptome sequencing revealed that nearly 20% of the S. mutans genes were differentially expressed upon SMU.2137 deletion, thereby suggesting a pleiotropic effect. Therefore, we have renamed this hitherto uncharacterized gene as sprV (streptococcal pleiotropic regulator of virulence). The transcript levels of several relevant genes in the sprV mutant corroborated the phenotypes observed upon sprV deletion. Owing to its highly conserved nature, inactivation of the sprV ortholog in Streptococcus gordonii also resulted in poor growth and defective UV tolerance and competence development as in the case of S. mutans. Our experiments suggest that SprV is functionally distinct from its homologs identified by structure and sequence homology. Nonetheless, our current work is aimed at understanding the importance of SprV in the S. mutans biology. IMPORTANCE Streptococcus mutans employs several virulence factors and stress resistance mechanisms to colonize tooth surfaces and cause dental caries. Bacterial pathogenesis is generally controlled by regulators of fitness that are critical for successful disease establishment. Sometimes these regulators, which are potential targets for antimicrobials, are lost in the genomic context due to the lack of annotated homologs. This work outlines the regulatory impact of a small, highly conserved hypothetical protein, SprV, encoded by S. mutans. We show that SprV affects the transcript levels of various virulence factors required for normal growth, biofilm formation, stress tolerance, genetic competence, and bacteriocin production. PMID:28167518

Search for Rare Copy-Number Variants in Congenital Heart Defects Identifies Novel Candidate Genes and a Potential Role for FOXC1 in Patients With Coarctation of the Aorta.

PubMed

Sanchez-Castro, Marta; Eldjouzi, Hadja; Charpentier, Eric; Busson, Pierre-François; Hauet, Quentin; Lindenbaum, Pierre; Delasalle-Guyomarch, Béatrice; Baudry, Adrien; Pichon, Olivier; Pascal, Cécile; Lefort, Bruno; Bajolle, Fanny; Pezard, Philippe; Schott, Jean-Jacques; Dina, Christian; Redon, Richard; Gournay, Véronique; Bonnet, Damien; Le Caignec, Cédric

2016-02-01

Congenital heart defects are the most frequent malformations among newborns and a frequent cause of morbidity and mortality. Although genetic variation contributes to congenital heart defects, their precise molecular bases remain unknown in the majority of patients. We analyzed, by high-resolution array comparative genomic hybridization, 316 children with sporadic, nonsyndromic congenital heart defects, including 76 coarctation of the aorta, 159 transposition of the great arteries, and 81 tetralogy of Fallot, as well as their unaffected parents. We identified by array comparative genomic hybridization, and validated by quantitative real-time polymerase chain reaction, 71 rare de novo (n=8) or inherited (n=63) copy-number variants (CNVs; 50 duplications and 21 deletions) in patients. We identified 113 candidate genes for congenital heart defects within these CNVs, including BTRC, CHRNB3, CSRP2BP, ERBB2, ERMARD, GLIS3, PLN, PTPRJ, RLN3, and TCTE3. No de novo CNVs were identified in patients with transposition of the great arteries in contrast to coarctation of the aorta and tetralogy of Fallot (P=0.002; Fisher exact test). A search for transcription factor binding sites showed that 93% of the rare CNVs identified in patients with coarctation of the aorta contained at least 1 gene with FOXC1-binding sites. This significant enrichment (P<0.0001; permutation test) was not observed for the CNVs identified in patients with transposition of the great arteries and tetralogy of Fallot. We hypothesize that these CNVs may alter the expression of genes regulated by FOXC1. Foxc1 belongs to the forkhead transcription factors family, which plays a critical role in cardiovascular development in mice. These data suggest that deregulation of FOXC1 or its downstream genes play a major role in the pathogenesis of coarctation of the aorta in humans. © 2015 American Heart Association, Inc.

Wolbachia-induced paternal defect in Drosophila is likely by interaction with the juvenile hormone pathway.

PubMed

Liu, Chen; Wang, Jia-Lin; Zheng, Ya; Xiong, En-Juan; Li, Jing-Jing; Yuan, Lin-Ling; Yu, Xiao-Qiang; Wang, Yu-Feng

2014-06-01

Wolbachia are endosymbionts that infect many insect species. They can manipulate the host's reproduction to increase their own maternal transmission. Cytoplasmic incompatibility (CI) is one such manipulation, which is expressed as embryonic lethality when Wolbachia-infected males mate with uninfected females. However, matings between males and females carrying the same Wolbachia strain result in viable progeny. The molecular mechanisms of CI are currently not clear. We have previously reported that the gene Juvenile hormone-inducible protein 26 (JhI-26) exhibited the highest upregulation in the 3rd instar larval testes of Drosophila melanogaster when infected by Wolbachia. This is reminiscent of an interaction between Wolbachia and juvenile hormone (JH) pathway in flies. Considering that Jhamt gene encodes JH acid methyltransferase, a key regulatory enzyme of JH biosynthesis, and that methoprene-tolerant (Met) has been regarded as the best JH receptor candidate, we first compared the expression of Jhamt and Met between Wolbachia-infected and uninfected fly testes to investigate whether Wolbachia infection influence the JH signaling pathway. We found that the expressions of Jhamt and Met were significantly increased in the presence of Wolbachia, suggesting an interaction of Wolbachia with the JH signaling pathway. Then, we found that overexpression of JhI-26 in Wolbachia-free transgenic male flies caused paternal-effect lethality that mimics the defects associated with CI. JhI-26 overexpressing males resulted in significantly decrease in hatch rate. Surprisingly, Wolbachia-infected females could rescue the egg hatch. In addition, we showed that overexpression of JhI-26 caused upregulation of the male accessory gland protein (Acp) gene CG10433, but not vice versa. This result suggests that JhI-26 may function at the upstream of CG10433. Likewise, overexpression of CG10433 also resulted in paternal-effect lethality. Both JhI-26 and CG10433 overexpressing males resulted in nuclear division defects in the early embryos. Finally, we found that Wolbachia-infected males decreased the propensity of the mated females to remating, a phenotype also caused by both JhI-26 and CG10433 overexpressing males. Taken together, our results provide a working hypothesis whereby Wolbachia induce paternal defects in Drosophila probably by interaction with the JH pathway via JH response genes JhI-26 and CG10433. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Clonal Genetic Screen for Mutants Causing Defects in Larval Tracheal Morphogenesis in Drosophila

PubMed Central

Baer, Magdalena M.; Bilstein, Andreas; Leptin, Maria

2007-01-01

The initial establishment of the tracheal network in the Drosophila embryo is beginning to be understood in great detail, both in its genetic control cascades and in its cell biological events. By contrast, the vast expansion of the system during larval growth, with its extensive ramification of preexisting tracheal branches, has been analyzed less well. The mutant phenotypes of many genes involved in this process are probably not easy to reveal, as these genes may be required for other functions at earlier developmental stages. We therefore conducted a screen for defects in individual clonal homozygous mutant cells in the tracheal network of heterozygous larvae using the mosaic analysis with a repressible cell marker (MARCM) system to generate marked, recombinant mitotic clones. We describe the identification of a set of mutants with distinct phenotypic effects. In particular we found a range of defects in terminal cells, including failure in lumen formation and reduced or extensive branching. Other mutations affect cell growth, cell shape, and cell migration. PMID:17603107

Alteration in levels of unsaturated fatty acids in mutants of Escherichia coli defective in DNA replication.

PubMed

Suzuki, E; Kondo, T; Makise, M; Mima, S; Sakamoto, K; Tsuchiya, T; Mizushima, T

1998-07-01

We previously reported that mutations in the dnaA gene which encodes the initiator of chromosomal DNA replication in Escherichia coli caused an alteration in the levels of unsaturated fatty acids of phospholipids in membranes. In this study, we examined fatty acid compositions in other mutants which are defective in DNA replication. As in the case of temperature-sensitive dnaA mutants, temperature-sensitive dnaC and dnaE mutants, which have defects in initiation and elongation, respectively, of DNA replication showed a lower level of unsaturation of fatty acids (ratio of unsaturated to saturated fatty acids) compared with the wild-type strain, especially at high temperatures. On the other hand, temperature-sensitive mutants defective in cellular processes other than DNA replication, such as RNA synthesis and cell division, did not show a lower level of unsaturation of fatty acids compared with the wild-type strain. These results suggest that the inhibition of DNA replication causes a lower level of unsaturation of fatty acids in Escherichia coli cells.

The intellectual capacity of patients with Laron syndrome (LS) differs with various molecular defects of the growth hormone receptor gene. Correlation with CNS abnormalities.

PubMed

Shevah, O; Kornreich, L; Galatzer, A; Laron, Z

2005-12-01

The correlation between the molecular defects of the GH receptor (R), psychosocial development and brain abnormalities were evaluated in 10 patients with Laron syndrome (LS), in whom all data were available. The findings revealed that the intelligence quotient (IQ) and abnormalities in the brain of the patients with LS differ with various molecular defects of the GH-receptor. The most severe mental deficits and brain pathology occurred in patients with 3, 5, 6 exon deletion. Patients with point mutations in exons 2, 4 and 7 presented various degrees of medium to mild CNS abnormalities that correlated with the IQ. Notably, the patient with the E180 splice mutation in exon 6 had a normal IQ, which fits the report on normal IQ in a large Ecuadorian cohort with the same mutation. This is the first report to support a correlation between IQ, brain abnormalities and localization of the molecular defects in the GH-R gene. As all patients with LS are IGF-I-deficient, it must be assumed that other as yet unknown factors related to the molecular defects in the GH-R are the major cause of the differences in intellect and brain abnormalities.

Clinical and Genetic Aspects of Primary Ciliary Dyskinesia / Kartagener Syndrome

PubMed Central

Leigh, Margaret W.; Pittman, Jessica E.; Carson, Johnny L.; Ferkol, Thomas W.; Dell, Sharon D.; Davis, Stephanie D.; Knowles, Michael R.; Zariwala, Maimoona A.

2013-01-01

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder of motile cilia. Most of the disease-causing mutations identified to date involve the heavy (DNAH5) or intermediate (DNAI1) chain dynein genes in ciliary outer dynein arms, although a few mutations have been noted in other genes. Clinical molecular genetic testing for PCD is available for the most common mutations. The respiratory manifestations of PCD (chronic bronchitis leading to bronchiectasis, chronic rhino-sinusitis and chronic otitis media) reflect impaired mucociliary clearance owing to defective axonemal structure. Ciliary ultrastructural analysis in most patients (>80%) reveals defective dynein arms, although defects in other axonemal components have also been observed. Approximately 50% of PCD patients have laterality defects (including situs inversus totalis and, less commonly, heterotaxy and congenital heart disease), reflecting dysfunction of embryological nodal cilia. Male infertility is common and reflects defects in sperm tail axonemes. Most PCD patients have a history of neonatal respiratory distress, suggesting that motile cilia play a role in fluid clearance during the transition from a fetal to neonatal lung. Ciliopathies involving sensory cilia, including autosomal dominant or recessive polycystic kidney disease, Bardet-Biedl syndrome, and Alstrom syndrome, may have chronic respiratory symptoms and even bronchiectasis suggesting clinical overlap with PCD. PMID:19606528

Primary Ciliary Dyskinesia Caused by Homozygous Mutation in DNAL1, Encoding Dynein Light Chain 1

PubMed Central

Mazor, Masha; Alkrinawi, Soliman; Chalifa-Caspi, Vered; Manor, Esther; Sheffield, Val C.; Aviram, Micha; Parvari, Ruti

2011-01-01

In primary ciliary dyskinesia (PCD), genetic defects affecting motility of cilia and flagella cause chronic destructive airway disease, randomization of left-right body asymmetry, and, frequently, male infertility. The most frequent defects involve outer and inner dynein arms (ODAs and IDAs) that are large multiprotein complexes responsible for cilia-beat generation and regulation, respectively. Although it has long been suspected that mutations in DNAL1 encoding the ODA light chain1 might cause PCD such mutations were not found. We demonstrate here that a homozygous point mutation in this gene is associated with PCD with absent or markedly shortened ODA. The mutation (NM_031427.3: c.449A>G; p.Asn150Ser) changes the Asn at position150, which is critical for the proper tight turn between the β strand and the α helix of the leucine-rich repeat in the hydrophobic face that connects to the dynein heavy chain. The mutation reduces the stability of the axonemal dynein light chain 1 and damages its interactions with dynein heavy chain and with tubulin. This study adds another important component to understanding the types of mutations that cause PCD and provides clinical information regarding a specific mutation in a gene not yet known to be associated with PCD. PMID:21496787

Application of exome sequencing in the search for genetic causes of rare disorders of copper metabolism.

PubMed

Fuchs, Sabine A; Harakalova, Magdalena; van Haaften, Gijs; van Hasselt, Peter M; Cuppen, Edwin; Houwen, Roderick H J

2012-07-01

The genetic defect in a number of rare disorders of metal metabolism remains elusive. The limited number of patients with these disorders impedes the identification of the causative gene through positional cloning, which requires numerous families with multiple affected individuals. However, with next-generation sequencing all coding DNA (exomes) or whole genomes of patients can be sequenced to identify genes that are consistently mutated in patients. With this strategy only a limited number of patients and/or pedigrees is needed, bringing the elucidation of the genetic cause of even very rare diseases within reach. The main challenge associated with whole exome sequencing is the identification of the disease-causing mutation(s) among abundant genetic candidate variants. We describe several strategies to manage this data wealth, including comparison with control databases, increasing the number of patients and controls, and reducing the genomic region under investigation through homozygosity mapping. In this review we introduce a number of rare disorders of copper metabolism, with a suspected but yet unknown monogenetic cause, as an attractive target for this strategy. We anticipate that use of these novel techniques will identify the basic defect in the disorders described in this review, as well as in other genetic disorders of metal metabolism, in the next few years.

Status of therapeutic gene transfer to treat canine dilated cardiomyopathy in dogs.

PubMed

Sleeper, Meg M; Bish, Lawrence T; Sweeney, H Lee

2010-07-01

Therapeutic gene transfer holds promise as a way to treat dilated cardiomyopathy from any underlying cause because the approach attempts to address metabolic disturbances that occur at the molecular level of the failing heart. Calcium-handling abnormalities and increased rates of apoptosis are abnormalities that occur in many types of heart disease, and gene therapies that target these metabolic defects have proven to be beneficial in numerous rodent models of heart disease. The authors are currently evaluating this approach to treat canine idiopathic dilated cardiomyopathy.

Molecular defects of the growth hormone receptor gene, including a new mutation, in Laron syndrome patients in Israel: relationship between defects and ethnic groups.

PubMed

Shevah, Orit; Rubinstein, Menachem; Laron, Zvi

2004-10-01

Laron Syndrome, first described in Israel, is a form of dwarfism similar to isolated growth hormone deficiency caused by molecular defects in the GH receptor gene. To characterize the molecular defects of the GH-R in Laron syndrome patients followed in our clinic. Of the 63 patients in the cohort, we investigated 31 patients and 32 relatives belonging to several ethnic origins. Molecular analysis of the GH-R gene was performed using the single strand conformation polymorphism and DNA sequencing techniques. Eleven molecular defects including a novel mutation were found. Twenty-two patients carried mutations in the extracellular domain, one in the transmembrane domain, and 3 siblings with typical Laron syndrome presented a normal GH-R. Of interest are, on one hand, different mutations within the same ethnic groups: W-15X and 5, 6 exon deletion in Jewish-Iraqis, and E180 splice and 5, 6 exon deletion in Jewish-Moroccans; and on the other hand, identical findings in patients from distinct regions: the 785-1 G to T mutation in an Israeli-Druze and a Peruvian patient. A polymorphism in exon 6, Gly168Gly, was found in 15 probands. One typical Laron patient from Greece was heterozygous for R43X in exon 4 and heterozygous for Gly168Gly. In addition, a novel mutation in exon 5: substitution of T to G replacing tyrosine 86 for aspartic acid (Y86D) is described. This study demonstrates: a) an increased focal incidence of Laron syndrome in different ethnic groups from our area with a high incidence of consanguinity; and b) a relationship between molecular defects of the GH-R, ethnic group and geographic area.

An inherited immunoglobulin class-switch recombination deficiency associated with a defect in the INO80 chromatin remodeling complex.

PubMed

Kracker, Sven; Di Virgilio, Michela; Schwartzentruber, Jeremy; Cuenin, Cyrille; Forveille, Monique; Deau, Marie-Céline; McBride, Kevin M; Majewski, Jacek; Gazumyan, Anna; Seneviratne, Suranjith; Grimbacher, Bodo; Kutukculer, Necil; Herceg, Zdenko; Cavazzana, Marina; Jabado, Nada; Nussenzweig, Michel C; Fischer, Alain; Durandy, Anne

2015-04-01

Immunoglobulin class-switch recombination defects (CSR-D) are rare primary immunodeficiencies characterized by impaired production of switched immunoglobulin isotypes and normal or elevated IgM levels. They are caused by impaired T:B cooperation or intrinsic B cell defects. However, many immunoglobulin CSR-Ds are still undefined at the molecular level. This study's objective was to delineate new causes of immunoglobulin CSR-Ds and thus gain further insights into the process of immunoglobulin class-switch recombination (CSR). Exome sequencing in 2 immunoglobulin CSR-D patients identified variations in the INO80 gene. Functional experiments were performed to assess the function of INO80 on immunoglobulin CSR. We identified recessive, nonsynonymous coding variations in the INO80 gene in 2 patients affected by defective immunoglobulin CSR. Expression of wild-type INO80 in patients' fibroblastic cells corrected their hypersensitivity to high doses of γ-irradiation. In murine CH12-F3 cells, the INO80 complex accumulates at Sα and Eμ regions of the IgH locus, and downregulation of INO80 as well as its partners Reptin and Pontin impaired CSR. In addition, Reptin and Pontin were shown to interact with activation-induced cytidine deaminase. Finally, an abnormal separation of sister chromatids was observed upon INO80 downregulation in CH12-F3 cells, pinpointing its role in cohesin activity. INO80 deficiency appears to be associated with defective immunoglobulin CSR. We propose that the INO80 complex modulates cohesin function that may be required during immunoglobulin switch region synapsis. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Pathophysiology of B-cell intrinsic immunoglobulin class switch recombination deficiencies.

PubMed

Durandy, Anne; Taubenheim, Nadine; Peron, Sophie; Fischer, Alain

2007-01-01

B-cell intrinsic immunoglobulin class switch recombination (Ig-CSR) deficiencies, previously termed hyper-IgM syndromes, are genetically determined conditions characterized by normal or elevated serum IgM levels and an absence or very low levels of IgG, IgA, and IgE. As a function of the molecular mechanism, the defective CSR is variably associated to a defect in the generation of somatic hypermutations (SHMs) in the Ig variable region. The study of Ig-CSR deficiencies contributed to a better delineation of the mechanisms underlying CSR and SHM, the major events of antigen-triggered antibody maturation. Four Ig-CSR deficiency phenotypes have been so far reported: the description of the activation-induced cytidine deaminase (AID) deficiency (Ig-CSR deficiency 1), caused by recessive mutations of AICDA gene, characterized by a defect in CSR and SHM, clearly established the role of AID in the induction of the Ig gene rearrangements underlying CSR and SHM. A CSR-specific function of AID has, however, been detected by the observation of a selective CSR defect caused by mutations affecting the C-terminus of AID. Ig-CSR deficiency 2 is the consequence of uracil-N-glycosylase (UNG) deficiency. Because UNG, a molecule of the base excision repair machinery, removes uracils from DNA and AID deaminates cytosines into uracils, that observation indicates that the AID-UNG pathway directly targets DNA of switch regions from the Ig heavy-chain locus to induce the CSR process. Ig-CSR deficiencies 3 and 4 are characterized by a selective CSR defect resulting from blocks at distinct steps of CSR. A further understanding of the CSR machinery is expected from their molecular definition.

Pharmacological correction of a defect in PPAR-gamma signaling ameliorates disease severity in Cftr-deficient mice.

PubMed

Harmon, Gregory S; Dumlao, Darren S; Ng, Damian T; Barrett, Kim E; Dennis, Edward A; Dong, Hui; Glass, Christopher K

2010-03-01

Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (encoded by Cftr) that impair its role as an apical chloride channel that supports bicarbonate transport. Individuals with cystic fibrosis show retained, thickened mucus that plugs airways and obstructs luminal organs as well as numerous other abnormalities that include inflammation of affected organs, alterations in lipid metabolism and insulin resistance. Here we show that colonic epithelial cells and whole lung tissue from Cftr-deficient mice show a defect in peroxisome proliferator-activated receptor-gamma (PPAR-gamma, encoded by Pparg) function that contributes to a pathological program of gene expression. Lipidomic analysis of colonic epithelial cells suggests that this defect results in part from reduced amounts of the endogenous PPAR-gamma ligand 15-keto-prostaglandin E(2) (15-keto-PGE(2)). Treatment of Cftr-deficient mice with the synthetic PPAR-gamma ligand rosiglitazone partially normalizes the altered gene expression pattern associated with Cftr deficiency and reduces disease severity. Rosiglitazone has no effect on chloride secretion in the colon, but it increases expression of the genes encoding carbonic anhydrases 4 and 2 (Car4 and Car2), increases bicarbonate secretion and reduces mucus retention. These studies reveal a reversible defect in PPAR-gamma signaling in Cftr-deficient cells that can be pharmacologically corrected to ameliorate the severity of the cystic fibrosis phenotype in mice.

Presynaptic congenital myasthenic syndrome with a homozygous sequence variant in LAMA5 combines myopia, facial tics, and failure of neuromuscular transmission.

PubMed

Maselli, Ricardo A; Arredondo, Juan; Vázquez, Jessica; Chong, Jessica X; Bamshad, Michael J; Nickerson, Deborah A; Lara, Marian; Ng, Fiona; Lo, Victoria L; Pytel, Peter; McDonald, Craig M

2017-08-01

Defects in genes encoding the isoforms of the laminin alpha subunit have been linked to various phenotypic manifestations, including brain malformations, muscular dystrophy, ocular defects, cardiomyopathy, and skin abnormalities. We report here a severe defect of neuromuscular transmission in a consanguineous patient with a homozygous variant in the laminin alpha-5 subunit gene (LAMA5). The variant c.8046C>T (p.Arg2659Trp) is rare and has a predicted deleterious effect. The affected individual, who also carries a rare homozygous sequence variant in LAMA1, had muscle weakness, myopia, and facial tics. Magnetic resonance imaging of brain showed mild volume loss and periventricular T2 prolongation. Repetitive nerve stimulation revealed 50% decrement of compound muscle action potential amplitudes and 250% facilitation immediately after exercise, Endplate studies identified a profound reduction of the endplate potential quantal content and endplates with normal postsynaptic folding that were denuded or partially occupied by small nerve terminals. Expression studies revealed that p.Arg2659Trp caused decreased binding of laminin alpha-5 to SV2A and impaired laminin-521 cell-adhesion and cell projection support in primary neuronal cultures. In summary, this report describing severe neuromuscular transmission failure in a patient with a LAMA5 mutation expands the list of phenotypes associated with defects in genes encoding alpha-laminins. © 2017 Wiley Periodicals, Inc.

High Throughput Sequencing Identifies Misregulated Genes in the Drosophila Polypyrimidine Tract-Binding Protein (hephaestus) Mutant Defective in Spermatogenesis.

PubMed

Sridharan, Vinod; Heimiller, Joseph; Robida, Mark D; Singh, Ravinder

2016-01-01

The Drosophila polypyrimidine tract-binding protein (dmPTB or hephaestus) plays an important role during spermatogenesis. The heph2 mutation in this gene results in a specific defect in spermatogenesis, causing aberrant spermatid individualization and male sterility. However, the array of molecular defects in the mutant remains uncharacterized. Using an unbiased high throughput sequencing approach, we have identified transcripts that are misregulated in this mutant. Aberrant transcripts show altered expression levels, exon skipping, and alternative 5' ends. We independently verified these findings by reverse-transcription and polymerase chain reaction (RT-PCR) analysis. Our analysis shows misregulation of transcripts that have been connected to spermatogenesis, including components of the actomyosin cytoskeletal apparatus. We show, for example, that the Myosin light chain 1 (Mlc1) transcript is aberrantly spliced. Furthermore, bioinformatics analysis reveals that Mlc1 contains a high affinity binding site(s) for dmPTB and that the site is conserved in many Drosophila species. We discuss that Mlc1 and other components of the actomyosin cytoskeletal apparatus offer important molecular links between the loss of dmPTB function and the observed developmental defect in spermatogenesis. This study provides the first comprehensive list of genes misregulated in vivo in the heph2 mutant in Drosophila and offers insight into the role of dmPTB during spermatogenesis.

Osteogenesis imperfecta.

PubMed

Forlino, Antonella; Marini, Joan C

2016-04-16

Osteogenesis imperfecta is a phenotypically and molecularly heterogeneous group of inherited connective tissue disorders that share similar skeletal abnormalities causing bone fragility and deformity. Previously, the disorder was thought to be an autosomal dominant bone dysplasia caused by defects in type I collagen, but in the past 10 years discoveries of novel (mainly recessive) causative genes have lent support to a predominantly collagen-related pathophysiology and have contributed to an improved understanding of normal bone development. Defects in proteins with very different functions, ranging from structural to enzymatic and from intracellular transport to chaperones, have been described in patients with osteogenesis imperfecta. Knowledge of the specific molecular basis of each form of the disorder will advance clinical diagnosis and potentially stimulate targeted therapeutic approaches. In this Seminar, together with diagnosis, management, and treatment, we describe the defects causing osteogenesis imperfecta and their mechanism and interrelations, and classify them into five groups on the basis of the metabolic pathway compromised, specifically those related to collagen synthesis, structure, and processing; post-translational modification; folding and cross-linking; mineralisation; and osteoblast differentiation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Amyloid precursor protein-induced axonopathies are independent of amyloid-beta peptides.

PubMed

Stokin, Gorazd B; Almenar-Queralt, Angels; Gunawardena, Shermali; Rodrigues, Elizabeth M; Falzone, Tomás; Kim, Jungsu; Lillo, Concepción; Mount, Stephanie L; Roberts, Elizabeth A; McGowan, Eileen; Williams, David S; Goldstein, Lawrence S B

2008-11-15

Overexpression of amyloid precursor protein (APP), as well as mutations in the APP and presenilin genes, causes rare forms of Alzheimer's disease (AD). These genetic changes have been proposed to cause AD by elevating levels of amyloid-beta peptides (Abeta), which are thought to be neurotoxic. Since overexpression of APP also causes defects in axonal transport, we tested whether defects in axonal transport were the result of Abeta poisoning of the axonal transport machinery. Because directly varying APP levels also alters APP domains in addition to Abeta, we perturbed Abeta generation selectively by combining APP transgenes in Drosophila and mice with presenilin-1 (PS1) transgenes harboring mutations that cause familial AD (FAD). We found that combining FAD mutant PS1 with FAD mutant APP increased Abeta42/Abeta40 ratios and enhanced amyloid deposition as previously reported. Surprisingly, however, this combination suppressed rather than increased APP-induced axonal transport defects in both Drosophila and mice. In addition, neuronal apoptosis induced by expression of FAD mutant human APP in Drosophila was suppressed by co-expressing FAD mutant PS1. We also observed that directly elevating Abeta with fusions to the Familial British and Danish Dementia-related BRI protein did not enhance axonal transport phenotypes in APP transgenic mice. Finally, we observed that perturbing Abeta ratios in the mouse by combining FAD mutant PS1 with FAD mutant APP did not enhance APP-induced behavioral defects. A potential mechanism to explain these findings was suggested by direct analysis of axonal transport in the mouse, which revealed that axonal transport or entry of APP into axons is reduced by FAD mutant PS1. Thus, we suggest that APP-induced axonal defects are not caused by Abeta.

Distinct cerebellar foliation anomalies in a CHD7 haploinsufficient mouse model of CHARGE syndrome

PubMed Central

Whittaker, Danielle E.; Kasah, Sahrunizam; Donovan, Alex P. A.; Ellegood, Jacob; Riegman, Kimberley L. H.; Volk, Holger A.; McGonnell, Imelda; Lerch, Jason P.

2017-01-01

Mutations in the gene encoding the ATP dependent chromatin‐remodeling factor, CHD7 are the major cause of CHARGE (Coloboma, Heart defects, Atresia of the choanae, Retarded growth and development, Genital‐urinary anomalies, and Ear defects) syndrome. Neurodevelopmental defects and a range of neurological signs have been identified in individuals with CHARGE syndrome, including developmental delay, lack of coordination, intellectual disability, and autistic traits. We previously identified cerebellar vermis hypoplasia and abnormal cerebellar foliation in individuals with CHARGE syndrome. Here, we report mild cerebellar hypoplasia and distinct cerebellar foliation anomalies in a Chd7 haploinsufficient mouse model. We describe specific alterations in the precise spatio‐temporal sequence of fissure formation during perinatal cerebellar development responsible for these foliation anomalies. The altered cerebellar foliation pattern in Chd7 haploinsufficient mice show some similarities to those reported in mice with altered Engrailed, Fgf8 or Zic1 gene expression and we propose that mutations or polymorphisms in these genes may modify the cerebellar phenotype in CHARGE syndrome. Our findings in a mouse model of CHARGE syndrome indicate that a careful analysis of cerebellar foliation may be warranted in patients with CHARGE syndrome, particularly in patients with cerebellar hypoplasia and developmental delay. PMID:29168327

Islands of non-essential genes, including a DNA translocation operon, in the genome of bacteriophage 0305ϕ8-36

PubMed Central

Pathria, Saurav; Rolando, Mandy; Lieman, Karen; Hayes, Shirley; Hardies, Stephen; Serwer, Philip

2012-01-01

We investigate genes of lytic, Bacillus thuringiensis bacteriophage 0305ϕ8-36 that are non-essential for laboratory propagation, but might have a function in the wild. We isolate deletion mutants to identify these genes. The non-permutation of the genome (218.948 Kb, with a 6.479 Kb terminal repeat and 247 identified orfs) simplifies isolation of deletion mutants. We find two islands of non-essential genes. The first island (3.01% of the genomic DNA) has an informatically identified DNA translocation operon. Deletion causes no detectable growth defect during propagation in a dilute agarose overlay. Identification of the DNA translocation operon begins with a DNA relaxase and continues with a translocase and membrane-binding anchor proteins. The relaxase is in a family, first identified here, with homologs in other bacteriophages. The second deleted island (3.71% of the genome) has genes for two metallo-protein chaperonins and two tRNAs. Deletion causes a significant growth defect. In addition, (1) we find by “in situ” (in-plaque) single-particle fluorescence microscopy that adsorption to the host occurs at the tip of the 486 nm long tail, (2) we develop a procedure of 0305ϕ8-36 purification that does not cause tail contraction, and (3) we then find by electron microscopy that 0305ϕ8-36 undergoes tail tip-tail tip dimerization that potentially blocks adsorption to host cells, presumably with effectiveness that increases as the bacteriophage particle concentration increases. These observations provide an explanation of the previous observation that 0305ϕ8-36 does not lyse liquid cultures, even though 0305ϕ8-36 is genomically lytic. PMID:22666654

Unexpected genetic heterogeneity for primary ciliary dyskinesia in the Irish Traveller population.

PubMed

Casey, Jillian P; McGettigan, Paul A; Healy, Fiona; Hogg, Claire; Reynolds, Alison; Kennedy, Breandan N; Ennis, Sean; Slattery, Dubhfeasa; Lynch, Sally A

2015-02-01

We present a study of five children from three unrelated Irish Traveller families presenting with primary ciliary dyskinesia (PCD). As previously characterized disorders in the Irish Traveller population are caused by common homozygous mutations, we hypothesised that all three PCD families shared the same recessive mutation. However, exome sequencing showed that there was no pathogenic homozygous mutation common to all families. This finding was supported by histology, which showed that each family has a different type of ciliary defect; transposition defect (family A), nude epithelium (family B) and absence of inner and outer dynein arms (family C). Therefore, each family was analysed independently using homozygosity mapping and exome sequencing. The affected siblings in family A share a novel 1 bp duplication in RSPH4A (NM_001161664.1:c.166dup; p.Arg56Profs*11), a radial-spoke head protein involved in ciliary movement. In family B, we identified three candidate genes (CCNO, KCNN3 and CDKN1C), with a 5-bp duplication in CCNO (NM_021147.3:c.258_262dup; p.Gln88Argfs*8) being the most likely cause of ciliary aplasia. This is the first study to implicate CCNO, a DNA repair gene reported to be involved in multiciliogenesis, in PCD. In family C, we identified a ∼3.5-kb deletion in DYX1C1, a neuronal migration gene previously associated with PCD. This is the first report of a disorder in the relatively small Irish Traveller population to be caused by >1 disease gene. Our study identified at least three different PCD genes in the Irish Traveller population, highlighting that one cannot always assume genetic homogeneity, even in small consanguineous populations.

Haploinsufficiency of BAZ1B contributes to Williams syndrome through transcriptional dysregulation of neurodevelopmental pathways.

PubMed

Lalli, Matthew A; Jang, Jiwon; Park, Joo-Hye C; Wang, Yidi; Guzman, Elmer; Zhou, Hongjun; Audouard, Morgane; Bridges, Daniel; Tovar, Kenneth R; Papuc, Sorina M; Tutulan-Cunita, Andreea C; Huang, Yadong; Budisteanu, Magdalena; Arghir, Aurora; Kosik, Kenneth S

2016-04-01

Williams syndrome (WS) is a neurodevelopmental disorder caused by a genomic deletion of ∼28 genes that results in a cognitive and behavioral profile marked by overall intellectual impairment with relative strength in expressive language and hypersocial behavior. Advancements in protocols for neuron differentiation from induced pluripotent stem cells allowed us to elucidate the molecular circuitry underpinning the ontogeny of WS. In patient-derived stem cells and neurons, we determined the expression profile of the Williams-Beuren syndrome critical region-deleted genes and the genome-wide transcriptional consequences of the hemizygous genomic microdeletion at chromosome 7q11.23. Derived neurons displayed disease-relevant hallmarks and indicated novel aberrant pathways in WS neurons including over-activated Wnt signaling accompanying an incomplete neurogenic commitment. We show that haploinsufficiency of the ATP-dependent chromatin remodeler, BAZ1B, which is deleted in WS, significantly contributes to this differentiation defect. Chromatin-immunoprecipitation (ChIP-seq) revealed BAZ1B target gene functions are enriched for neurogenesis, neuron differentiation and disease-relevant phenotypes. BAZ1B haploinsufficiency caused widespread gene expression changes in neural progenitor cells, and together with BAZ1B ChIP-seq target genes, explained 42% of the transcriptional dysregulation in WS neurons. BAZ1B contributes to regulating the balance between neural precursor self-renewal and differentiation and the differentiation defect caused by BAZ1B haploinsufficiency can be rescued by mitigating over-active Wnt signaling in neural stem cells. Altogether, these results reveal a pivotal role for BAZ1B in neurodevelopment and implicate its haploinsufficiency as a likely contributor to the neurological phenotypes in WS. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Loss of polyadenylation protein τCstF-64 causes spermatogenic defects and male infertility

PubMed Central

Dass, Brinda; Tardif, Steve; Park, Ji Yeon; Tian, Bin; Weitlauf, Harry M.; Hess, Rex A.; Carnes, Kay; Griswold, Michael D.; Small, Christopher L.; MacDonald, Clinton C.

2007-01-01

Polyadenylation, the process of eukaryotic mRNA 3′ end formation, is essential for gene expression and cell viability. Polyadenylation of male germ cell mRNAs is unusual, exhibiting increased alternative polyadenylation, decreased AAUAAA polyadenylation signal use, and reduced downstream sequence element dependence. CstF-64, the RNA-binding component of the cleavage stimulation factor (CstF), interacts with pre-mRNAs at sequences downstream of the cleavage site. In mammalian testes, meiotic XY-body formation causes suppression of X-linked CstF-64 expression during pachynema. Consequently, an autosomal paralog, τCstF-64 (gene name Cstf2t), is expressed during meiosis and subsequent haploid differentiation. Here we show that targeted disruption of Cstf2t in mice causes aberrant spermatogenesis, specifically disrupting meiotic and postmeiotic development, resulting in male infertility resembling oligoasthenoteratozoospermia. Furthermore, the Cstf2t mutant phenotype displays variable expressivity such that spermatozoa show a broad range of defects. The overall phenotype is consistent with a requirement for τCstF-64 in spermatogenesis as indicated by the significant changes in expression of thousands of genes in testes of Cstf2t−/− mice as measured by microarray. Our results indicate that, although the infertility in Cstf2t−/− males is due to low sperm count, multiple genes controlling many aspects of germ-cell development depend on τCstF-64 for their normal expression. Finally, these transgenic mice provide a model for the study of polyadenylation in an isolated in vivo system and highlight the role of a growing family of testis-expressed autosomal retroposed variants of X-linked genes. PMID:18077340

Restoration of Motor Defects Caused by Loss of Drosophila TDP-43 by Expression of the Voltage-Gated Calcium Channel, Cacophony, in Central Neurons.

PubMed

Lembke, Kayly M; Scudder, Charles; Morton, David B

2017-09-27

Defects in the RNA-binding protein, TDP-43, are known to cause a variety of neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal lobar dementia. A variety of experimental systems have shown that neurons are sensitive to TDP-43 expression levels, yet the specific functional defects resulting from TDP-43 dysregulation have not been well described. Using the Drosophila TDP-43 ortholog TBPH, we previously showed that TBPH-null animals display locomotion defects as third instar larvae. Furthermore, loss of TBPH caused a reduction in cacophony , a Type II voltage-gated calcium channel, expression and that genetically restoring cacophony in motor neurons in TBPH mutant animals was sufficient to rescue the locomotion defects. In the present study, we examined the relative contributions of neuromuscular junction physiology and the motor program to the locomotion defects and identified subsets of neurons that require cacophony expression to rescue the defects. At the neuromuscular junction, we showed mEPP amplitudes and frequency require TBPH. Cacophony expression in motor neurons rescued mEPP frequency but not mEPP amplitude. We also showed that TBPH mutants displayed reduced motor neuron bursting and coordination during crawling and restoring cacophony selectively in two pairs of cells located in the brain, the AVM001b/2b neurons, also rescued the locomotion and motor defects, but not the defects in neuromuscular junction physiology. These results suggest that the behavioral defects associated with loss of TBPH throughout the nervous system can be associated with defects in a small number of genes in a limited number of central neurons, rather than peripheral defects. SIGNIFICANCE STATEMENT TDP-43 dysfunction is a common feature in neurodegenerative diseases, including amyotrophic lateral sclerosis, frontotemporal lobar dementia, and Alzheimer's disease. Loss- and gain-of-function models have shown that neurons are sensitive to TDP-43 expression levels, but the specific defects caused by TDP-43 loss of function have not been described in detail. A Drosophila loss-of-function model displays pronounced locomotion defects that can be reversed by restoring the expression levels of a voltage-gated calcium channel, cacophony. We show these defects can be rescued by expression of cacophony in motor neurons and by expression in two pairs of neurons in the brain. These data suggest that loss of TDP-43 can disrupt the central circuitry of the CNS, opening up identification of alternative therapeutic targets for TDP-43 proteinopathies. Copyright © 2017 the authors 0270-6474/17/379486-12$15.00/0.

CRISPR-Cas9 Corrects Mutation in Immune Disorder, Suggesting New Therapeutic Approach | Frederick National Laboratory for Cancer Research

Cancer.gov

Gene editing using the powerful new CRISPR-Cas9 system is showing promise as a tool for developing potential treatments for inherited diseases, particularly for those caused by single genetic defects. Examples of these diseases are cystic fibrosis, m

Roles of lignin biosynthesis and regulatory genes in plant development

PubMed Central

Yoon, Jinmi; Choi, Heebak

2015-01-01

Abstract Lignin is an important factor affecting agricultural traits, biofuel production, and the pulping industry. Most lignin biosynthesis genes and their regulatory genes are expressed mainly in the vascular bundles of stems and leaves, preferentially in tissues undergoing lignification. Other genes are poorly expressed during normal stages of development, but are strongly induced by abiotic or biotic stresses. Some are expressed in non‐lignifying tissues such as the shoot apical meristem. Alterations in lignin levels affect plant development. Suppression of lignin biosynthesis genes causes abnormal phenotypes such as collapsed xylem, bending stems, and growth retardation. The loss of expression by genes that function early in the lignin biosynthesis pathway results in more severe developmental phenotypes when compared with plants that have mutations in later genes. Defective lignin deposition is also associated with phenotypes of seed shattering or brittle culm. MYB and NAC transcriptional factors function as switches, and some homeobox proteins negatively control lignin biosynthesis genes. Ectopic deposition caused by overexpression of lignin biosynthesis genes or master switch genes induces curly leaf formation and dwarfism. PMID:26297385

Nipbl and mediator cooperatively regulate gene expression to control limb development.

PubMed

Muto, Akihiko; Ikeda, Shingo; Lopez-Burks, Martha E; Kikuchi, Yutaka; Calof, Anne L; Lander, Arthur D; Schilling, Thomas F

2014-09-01

Haploinsufficiency for Nipbl, a cohesin loading protein, causes Cornelia de Lange Syndrome (CdLS), the most common "cohesinopathy". It has been proposed that the effects of Nipbl-haploinsufficiency result from disruption of long-range communication between DNA elements. Here we use zebrafish and mouse models of CdLS to examine how transcriptional changes caused by Nipbl deficiency give rise to limb defects, a common condition in individuals with CdLS. In the zebrafish pectoral fin (forelimb), knockdown of Nipbl expression led to size reductions and patterning defects that were preceded by dysregulated expression of key early limb development genes, including fgfs, shha, hand2 and multiple hox genes. In limb buds of Nipbl-haploinsufficient mice, transcriptome analysis revealed many similar gene expression changes, as well as altered expression of additional classes of genes that play roles in limb development. In both species, the pattern of dysregulation of hox-gene expression depended on genomic location within the Hox clusters. In view of studies suggesting that Nipbl colocalizes with the mediator complex, which facilitates enhancer-promoter communication, we also examined zebrafish deficient for the Med12 Mediator subunit, and found they resembled Nipbl-deficient fish in both morphology and gene expression. Moreover, combined partial reduction of both Nipbl and Med12 had a strongly synergistic effect, consistent with both molecules acting in a common pathway. In addition, three-dimensional fluorescent in situ hybridization revealed that Nipbl and Med12 are required to bring regions containing long-range enhancers into close proximity with the zebrafish hoxda cluster. These data demonstrate a crucial role for Nipbl in limb development, and support the view that its actions on multiple gene pathways result from its influence, together with Mediator, on regulation of long-range chromosomal interactions.

Mutations in NONO lead to syndromic intellectual disability and inhibitory synaptic defects.

PubMed

Mircsof, Dennis; Langouët, Maéva; Rio, Marlène; Moutton, Sébastien; Siquier-Pernet, Karine; Bole-Feysot, Christine; Cagnard, Nicolas; Nitschke, Patrick; Gaspar, Ludmila; Žnidarič, Matej; Alibeu, Olivier; Fritz, Ann-Kristina; Wolfer, David P; Schröter, Aileen; Bosshard, Giovanna; Rudin, Markus; Koester, Christina; Crestani, Florence; Seebeck, Petra; Boddaert, Nathalie; Prescott, Katrina; Hines, Rochelle; Moss, Steven J; Fritschy, Jean-Marc; Munnich, Arnold; Amiel, Jeanne; Brown, Steven A; Tyagarajan, Shiva K; Colleaux, Laurence

2015-12-01

The NONO protein has been characterized as an important transcriptional regulator in diverse cellular contexts. Here we show that loss of NONO function is a likely cause of human intellectual disability and that NONO-deficient mice have cognitive and affective deficits. Correspondingly, we find specific defects at inhibitory synapses, where NONO regulates synaptic transcription and gephyrin scaffold structure. Our data identify NONO as a possible neurodevelopmental disease gene and highlight the key role of the DBHS protein family in functional organization of GABAergic synapses.

Kinesin Mutations Cause Motor Neuron Disease Phenotypes by Disrupting Fast Axonal Transport in Drosophila

PubMed Central

Hurd, D. D.; Saxton, W. M.

1996-01-01

Previous work has shown that mutation of the gene that encodes the microtubule motor subunit kinesin heavy chain (Khc) in Drosophila inhibits neuronal sodium channel activity, action potentials and neurotransmitter secretion. These physiological defects cause progressive distal paralysis in larvae. To identify the cellular defects that cause these phenotypes, larval nerves were studied by light and electron microscopy. The axons of Khc mutants develop dramatic focal swellings along their lengths. The swellings are packed with fast axonal transport cargoes including vesicles, synaptic membrane proteins, mitochondria and prelysosomal organelles, but not with slow axonal transport cargoes such as cytoskeletal elements. Khc mutations also impair the development of larval motor axon terminals, causing dystrophic morphology and marked reductions in synaptic bouton numbers. These observations suggest that as the concentration of maternally provided wild-type KHC decreases, axonal organelles transported by kinesin periodically stall. This causes organelle jams that disrupt retrograde as well as anterograde fast axonal transport, leading to defective action potentials, dystrophic terminals, reduced transmitter secretion and progressive distal paralysis. These phenotypes parallel the pathologies of some vertebrate motor neuron diseases, including some forms of amyotrophic lateral sclerosis (ALS), and suggest that impaired fast axonal transport is a key element in those diseases. PMID:8913751

Bone tissue ultrastructural defects in a mouse model for osteogenesis imperfecta: a Raman spectroscopy study

NASA Astrophysics Data System (ADS)

Chen, Tsoching; Kozloff, Kenneth M.; Goldstein, Steven A.; Morris, Michael D.

2004-07-01

Osteogenesis imperfecta (OI) is genetic defect in which the genes that code for the α1(I) or α2(I) chains of type I collagen are defective. The defects often result in substitution of a bulky amino acid for glycine, causing formation of collagen that can not form the normal triple helix. Depending on the details of the defects, the outcomes range from controllable to lethal. This study focuses on OI type IV, a more common and moderately severe form of the disease. People with the disease have a substantial increase in the risk and rate of fracture. We examine the spectroscopic consequences of these defects, using a mouse model (BRTL) that mimics OI type IV. We compare Raman images from tibial cortical tissue of wild-type mice and BRTL mice with single copy of mutation and show that both mineral to matrix ratios and collagen inter-fibril cross-links are different in wild-type and mutant mice.

Genes affecting sensitivity to serotonin in Caenorhabditis elegans.

PubMed

Schafer, W R; Sanchez, B M; Kenyon, C J

1996-07-01

Regulating the response of a postsynaptic cell to neurotransmitter is an important mechanism for controlling synaptic strength, a process critical to learning. We have begun to define and characterize genes that may control sensitivity to the neurotransmitter serotonin in the nematode Caenorhabditis elegans by identifying serotonin-hypersensitive mutants. We reported previously that mutations in the gene unc-2, which encodes a putative calcium channel subunit, result in hypersensitivity to serotonin. Here we report that mutants defective in the unc-36 gene, which encodes a homologue of a calcium channel auxiliary subunit, are also serotonin-hypersensitive. Moreover, the unc-36 gene appears to be required in the same cells as unc-2 for control of the same behaviors. Mutations in several other genes, including unc-8, unc-10, unc-20, unc-35, unc-75, unc-77, and snt-1 also result in hypersensitivity to serotonin. Several of these mutations have previously been shown to confer resistance to acetylcholinesterase inhibitors, suggesting that they may affect acetylcholine release. Moreover, we found that mutations that decrease acetylcholine synthesis cause defective egg-laying and serotonin hypersensitivity. Thus, acetylcholine appears to negatively regulate the response to serotonin and may participate in the process of serotonin desensitization.

Genes Affecting Sensitivity to Serotonin in Caenorhabditis Elegans

PubMed Central

Schafer, W. R.; Sanchez, B. M.; Kenyon, C. J.

1996-01-01

Regulating the response of a postsynaptic cell to neurotransmitter is an important mechanism for controlling synaptic strength, a process critical to learning. We have begun to define and characterize genes that may control sensitivity to the neurotransmitter serotonin in the nematode Caenorhabditis elegans by identifying serotonin-hypersensitive mutants. We reported previously that mutations in the gene unc-2, which encodes a putative calcium channel subunit, result in hypersensitivity to serotonin. Here we report that mutants defective in the unc-36 gene, which encodes a homologue of a calcium channel auxiliary subunit, are also serotonin-hypersensitive. Moreover, the unc-36 gene appears to be required in the same cells as unc-2 for control of the same behaviors. Mutations in several other genes, including unc-8, unc-10, unc-20, unc-35, unc-75, unc-77, and snt-1 also result in hypersensitivity to serotonin. Several of these mutations have previously been shown to confer resistance to acetylcholinesterase inhibitors, suggesting that they may affect acetylcholine release. Moreover, we found that mutations that decrease acetylcholine synthesis cause defective egg-laying and serotonin hypersensitivity. Thus, acetylcholine appears to negatively regulate the response to serotonin and may participate in the process of serotonin desensitization. PMID:8807295

The ciliopathy gene Rpgrip1l is essential for hair follicle development.

PubMed

Chen, Jiang; Laclef, Christine; Moncayo, Alejandra; Snedecor, Elizabeth R; Yang, Ning; Li, Li; Takemaru, Ken-Ichi; Paus, Ralf; Schneider-Maunoury, Sylvie; Clark, Richard A

2015-03-01

The primary cilium is essential for skin morphogenesis through regulating the Notch, Wnt, and hedgehog signaling pathways. Prior studies on the functions of primary cilia in the skin were based on the investigations of genes that are essential for cilium formation. However, none of these ciliogenic genes has been linked to ciliopathy, a group of disorders caused by abnormal formation or function of cilia. To determine whether there is a genetic and molecular link between ciliopathies and skin morphogenesis, we investigated the role of RPGRIP1L, a gene mutated in Joubert (JBTS) and Meckel (MKS) syndromes, two severe forms of ciliopathy, in the context of skin development. We found that RPGRIP1L is essential for hair follicle morphogenesis. Specifically, disrupting the Rpgrip1l gene in mice resulted in reduced proliferation and differentiation of follicular keratinocytes, leading to hair follicle developmental defects. These defects were associated with significantly decreased primary cilium formation and attenuated hedgehog signaling. In contrast, we found that hair follicle induction and polarization and the development of interfollicular epidermis were unaffected. This study indicates that RPGRIP1L, a ciliopathy gene, is essential for hair follicle morphogenesis likely through regulating primary cilia formation and the hedgehog signaling pathway.

Atelosteogenesis type II is caused by mutations in the diastrophic dysplasia sulfate-transporter gene (DTDST): Evidence for a phenotypic series involving three chondrodysplasias

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haestbacka, J.; Lander, E.S.; Superti-Furga, A.

1996-02-01

Atelosteogenesis type II (AO II) is a neonatally lethal chondrodysplasia whose clinical and histological characteristics resemble those of another chondrodysplasia, the much less severe diastrophic dysplasia (DTD). The similarity suggests a shared pathogenesis involving lesions in the same biochemical pathway and perhaps the same gene. DTD is caused by mutations in the recently identified diastrophic dysplasia sulfate-transporter gene (DTDST). Here, we report that AOII patients also have DTDST mutations, which lead to defective uptake of inorganic sulfate and insufficient sulfation of macromolecules by patient mesenchymal cells in vitro. Together with our recent observation that a third even more severe chondrodysplasia,more » achondrogenesis type IB, is also caused by mutations in DTDST, these results demonstrate a phenotypic series of three chondrodysplasias of increasing severity caused by lesions in a single sulfate-transporter gene. The severity of the phenotype appears to be correlated with the predicted effect of the mutations on the residual activity of the DTDST protein. 24 refs., 6 figs., 1 tab.« less

Carney Complex: an update

PubMed Central

Correa, Ricardo; Salpea, Paraskevi; Stratakis, Constantine

2015-01-01

Carney Complex (CNC) is a rare autosomal dominant syndrome, characterized by pigmented lesions of the skin and mucosa, cardiac, cutaneous and other myxomas, and multiple endocrine tumors. The disease is caused by inactivating mutations or large deletions of the PRKAR1A gene located at 17q22–24 coding for the regulatory subunit type I alpha of protein kinase A (PKA) gene. Most recently, components of the complex have been associated with defects of other PKA subunits, such as the catalytic subunits PRKACA (adrenal hyperplasia) and PRKACB (pigmented spots, myxomas, pituitary adenomas). In this report, we review CNC, its clinical features, diagnosis, treatment, and molecular etiology including PRKAR1A mutations and the newest on PRKACA and PRKACB defects especially as they pertain to adrenal tumors and Cushing’s syndrome. PMID:26130139

Alteration of gene expression by alcohol exposure at early neurulation.

PubMed

Zhou, Feng C; Zhao, Qianqian; Liu, Yunlong; Goodlett, Charles R; Liang, Tiebing; McClintick, Jeanette N; Edenberg, Howard J; Li, Lang

2011-02-21

We have previously demonstrated that alcohol exposure at early neurulation induces growth retardation, neural tube abnormalities, and alteration of DNA methylation. To explore the global gene expression changes which may underline these developmental defects, microarray analyses were performed in a whole embryo mouse culture model that allows control over alcohol and embryonic variables. Alcohol caused teratogenesis in brain, heart, forelimb, and optic vesicle; a subset of the embryos also showed cranial neural tube defects. In microarray analysis (accession number GSM9545), adopting hypothesis-driven Gene Set Enrichment Analysis (GSEA) informatics and intersection analysis of two independent experiments, we found that there was a collective reduction in expression of neural specification genes (neurogenin, Sox5, Bhlhe22), neural growth factor genes [Igf1, Efemp1, Klf10 (Tieg), and Edil3], and alteration of genes involved in cell growth, apoptosis, histone variants, eye and heart development. There was also a reduction of retinol binding protein 1 (Rbp1), and de novo expression of aldehyde dehydrogenase 1B1 (Aldh1B1). Remarkably, four key hematopoiesis genes (glycophorin A, adducin 2, beta-2 microglobulin, and ceruloplasmin) were absent after alcohol treatment, and histone variant genes were reduced. The down-regulation of the neurospecification and the neurotrophic genes were further confirmed by quantitative RT-PCR. Furthermore, the gene expression profile demonstrated distinct subgroups which corresponded with two distinct alcohol-related neural tube phenotypes: an open (ALC-NTO) and a closed neural tube (ALC-NTC). Further, the epidermal growth factor signaling pathway and histone variants were specifically altered in ALC-NTO, and a greater number of neurotrophic/growth factor genes were down-regulated in the ALC-NTO than in the ALC-NTC embryos. This study revealed a set of genes vulnerable to alcohol exposure and genes that were associated with neural tube defects during early neurulation.

Comprehensive Mutation Scanning of LMNA in 268 Patients With Lone Atrial Fibrillation

PubMed Central

Brauch, Katharine M.; Chen, Lin Y.; Olson, Timothy M.

2009-01-01

Atrial fibrillation (AF) is a heritable, genetically heterogeneous disorder. To identify gene defects that cause or confer susceptibility to AF, a cohort of 268 unrelated patients with idiopathic forms of familial and sporadic AF was recruited. LMNA, encoding the nuclear membrane proteins, lamin A/C, was selected as a candidate gene for lone AF based on its established association with a syndrome of dilated cardiomyopathy, conduction system disease, and AF. Comprehensive mutation scanning identified only 1 potentially pathogenic mutation. In conclusion, LMNA mutations rarely cause lone AF and routine genetic testing of LMNA in these patients does not appear warranted. PMID:19427440

Defective complex I assembly due to C20orf7 mutations as a new cause of Leigh syndrome

PubMed Central

Gerards, M; Sluiter, W; van den Bosch, B J C; de Wit, L E A; Calis, C M H; Frentzen, M; Akbari, H; Schoonderwoerd, K; Scholte, H R; Jongbloed, R J; Hendrickx, A T M; de Coo, I F M

2009-01-01

Background Leigh syndrome is an early onset, progressive, neurodegenerative disorder with developmental and motor skills regression. Characteristic magnetic resonance imaging abnormalities consist of focal bilateral lesions in the basal ganglia and/or the brainstem. The main cause is a deficiency in oxidative phosphorylation due to mutations in an mtDNA or nuclear oxidative phosphorylation gene. Methods and results A consanguineous Moroccan family with Leigh syndrome comprise 11 children, three of which are affected. Marker analysis revealed a homozygous region of 11.5 Mb on chromosome 20, containing 111 genes. Eight possible mitochondrial candidate genes were sequenced. Patients were homozygous for an unclassified variant (p.P193L) in the cardiolipin synthase gene (CRLS1). As this variant was present in 20% of a Moroccan control population and enzyme activity was only reduced to 50%, this could not explain the rare clinical phenotype in our family. Patients were also homozygous for an amino acid substitution (p.L159F) in C20orf7, a new complex I assembly factor. Parents were heterozygous and unaffected sibs heterozygous or homozygous wild type. The mutation affects the predicted S-adenosylmethionine (SAM) dependent methyltransferase domain of C20orf7, possibly involved in methylation of NDUFB3 during the assembly process. Blue native gel electrophoresis showed an altered complex I assembly with only 30–40% of mature complex I present in patients and 70–90% in carriers. Conclusions A new cause of Leigh syndrome can be a defect in early complex I assembly due to C20orf7 mutations. PMID:19542079

Novel ENAM and LAMB3 mutations in Chinese families with hypoplastic amelogenesis imperfecta.

PubMed

Wang, Xin; Zhao, Yuming; Yang, Yuan; Qin, Man

2015-01-01

Amelogenesis imperfecta is a group of inherited diseases affecting the quality and quantity of dental enamel. To date, mutations in more than ten genes have been associated with non-syndromic amelogenesis imperfecta (AI). Among these, ENAM and LAMB3 mutations are known to be parts of the etiology of hypoplastic AI in human cases. When both alleles of LAMB3 are defective, it could cause junctional epidermolysis bullosa (JEB), while with only one mutant allele in the C-terminus of LAMB3, it could result in severe hypoplastic AI without skin fragility. We enrolled three Chinese families with hypoplastic autosomal-dominant AI. Despite the diagnosis falling into the same type, the characteristics of their enamel hypoplasia were different. Screening of ENAM and LAMB3 genes was performed by direct sequencing of genomic DNA from blood samples. Disease-causing mutations were identified and perfectly segregated with the enamel defects in three families: a 19-bp insertion mutation in the exon 7 of ENAM (c.406_407insTCAAAAAAGCCGACCACAA, p.K136Ifs*16) in Family 1, a single-base deletion mutation in the exon 5 of ENAM (c. 139delA, p. M47Cfs*11) in Family 2, and a LAMB3 nonsense mutation in the last exon (c.3466C>T, p.Q1156X) in Family 3. Our results suggest that heterozygous mutations in ENAM and LAMB3 genes can cause hypoplastic AI with markedly different phenotypes in Chinese patients. And these findings extend the mutation spectrum of both genes and can be used for mutation screening of AI in the Chinese population.

Fulminant neurological deterioration in a neonate with Leigh syndrome due to a maternally transmitted missense mutation in the mitochondrial ND3 gene.

PubMed

Leshinsky-Silver, E; Lev, D; Tzofi-Berman, Z; Cohen, S; Saada, A; Yanoov-Sharav, M; Gilad, E; Lerman-Sagie, T

2005-08-26

Leigh syndrome can result from both nuclear and mitochondrial DNA defects. Mutations in complex V genes of the respiratory chain were considered until recently as the most frequent cause for mitochondrial inherited Leigh syndrome, while gene defects in complex I were related to recessive Leigh syndrome. Recently few reports of mutations in the mitochondrial-encoded complex I subunit genes causing Leigh syndrome have been reported. We describe a 1-month-old baby who acutely deteriorated, with abrupt onset of brainstem dysfunction, due to basal ganglia lesions extending to the brainstem. A muscle biopsy demonstrated complex I deficiency. Subsequent analysis of the mitochondrial genome revealed a homoplastic T10191C mutation in the ND3 gene (in blood and muscle), resulting in a substitution of serine to proline. Hair root analysis revealed a 50% mutant load, reflecting heteroplasmy in early embryonic stages. The mutation was also detected in his mother (5%). Western blot analysis revealed a decrease of the 20 kDa subunit (likely ND6) and of the 30 kDa subunit (NDUFA9), which is probably due to instability attributed to the inability to form subcomplexes with ND3. This is the first description of infantile Leigh syndrome due to a maternally transmitted T10191C substitution in ND3 and not due to a de novo mutation. This mutation is age and tissue dependent and therefore may not be amenable to prenatal testing.

Pax2 regulates a fadd-dependent molecular switch that drives tissue fusion during eye development.

PubMed

Viringipurampeer, Ishaq A; Ferreira, Todd; DeMaria, Shannon; Yoon, Jookyung J; Shan, Xianghong; Moosajee, Mariya; Gregory-Evans, Kevin; Ngai, John; Gregory-Evans, Cheryl Y

2012-05-15

Tissue fusion is an essential morphogenetic mechanism in development, playing a fundamental role in developing neural tube, palate and the optic fissure. Disruption of genes associated with the tissue fusion can lead to congenital malformations, such as spina bifida, cleft lip/palate and ocular coloboma. For instance, the Pax2 transcription factor is required for optic fissure closure, although the mechanism of Pax2 action leading to tissue fusion remains elusive. This lack of information defining how transcription factors drive tissue morphogenesis at the cellular level is hampering new treatments options. Through loss- and gain-of-function analysis, we now establish that pax2 in combination with vax2 directly regulate the fas-associated death domain (fadd) gene. In the presence of fadd, cell proliferation is restricted in the developing eye through a caspase-dependent pathway. However, the loss of fadd results in a proliferation defect and concomitant activation of the necroptosis pathway through RIP1/RIP3 activity, leading to an abnormal open fissure. Inhibition of RIP1 with the small molecule drug necrostatin-1 rescues the pax2 eye fusion defect, thereby overcoming the underlying genetic defect. Thus, fadd has an essential physiological function in protecting the developing optic fissure neuroepithelium from RIP3-dependent necroptosis. This study demonstrates the molecular hierarchies that regulate a cellular switch between proliferation and the apoptotic and necroptotic cell death pathways, which in combination drive tissue morphogenesis. Furthermore, our data suggest that future therapeutic strategies may be based on small molecule drugs that can bypass the gene defects causing common congenital tissue fusion defects.

Infection of Mice by Salmonella enterica Serovar Enteritidis Involves Additional Genes That Are Absent in the Genome of Serovar Typhimurium

PubMed Central

Silva, Cecilia A.; Blondel, Carlos J.; Quezada, Carolina P.; Porwollik, Steffen; Andrews-Polymenis, Helene L.; Toro, Cecilia S.; Zaldívar, Mercedes; Contreras, Inés

2012-01-01

Salmonella enterica serovar Enteritidis causes a systemic, typhoid-like infection in newly hatched poultry and mice. In the present study, a library of 54,000 transposon mutants of S. Enteritidis phage type 4 (PT4) strain P125109 was screened for mutants deficient in the in vivo colonization of the BALB/c mouse model using a microarray-based negative-selection screening. Mutants in genes known to contribute to systemic infection (e.g., Salmonella pathogenicity island 2 [SPI-2], aro, rfa, rfb, phoP, and phoQ) and enteric infection (e.g., SPI-1 and SPI-5) in this and other Salmonella serovars displayed colonization defects in our assay. In addition, a strong attenuation was observed for mutants in genes and genomic islands that are not present in S. Typhimurium or in most other Salmonella serovars. These genes include a type I restriction/modification system (SEN4290 to SEN4292), the peg fimbrial operon (SEN2144A to SEN2145B), a putative pathogenicity island (SEN1970 to SEN1999), and a type VI secretion system remnant SEN1001, encoding a hypothetical protein containing a lysin motif (LysM) domain associated with peptidoglycan binding. Proliferation defects for mutants in these individual genes and in exemplar genes for each of these clusters were confirmed in competitive infections with wild-type S. Enteritidis. A ΔSEN1001 mutant was defective for survival within RAW264.7 murine macrophages in vitro. Complementation assays directly linked the SEN1001 gene to phenotypes observed in vivo and in vitro. The genes identified here may perform novel virulence functions not characterized in previous Salmonella models. PMID:22083712

Understanding diabetic teratogenesis: where are we now and where are we going?

PubMed

Zabihi, Sheller; Loeken, Mary R

2010-10-01

Maternal pregestational diabetes (type 1 or type 2) poses an increased risk for a broad spectrum of birth defects. To our knowledge, this problem first came to the attention of the Teratology Society at the 14th Annual Meeting in Vancouver, B.C. in 1974, with a presentation by Lewis Holmes, "Etiologic heterogeneity of neural tube defects". Although advances in the control of diabetes in the decades since the discovery of insulin in the 1920's have reduced the risk for birth defects during diabetic pregnancy, the increasing incidence of diabetes among women of childbearing years indicates that this cause of birth defects is a growing public health concern. Major advances in understanding how a disease of maternal fuel metabolism can interfere with embryogenesis of multiple organ systems have been made in recent years. In this review, we trace the history of the study of diabetic teratogenesis and discuss a model in which tissue-specific developmental control genes are regulated at specific times in embryonic development by glucose metabolism. The major function of such genes is to suppress apoptosis, perhaps to preserve proliferative capability, and inhibit premature senescence. © 2010 Wiley-Liss, Inc.

Metaphase to Anaphase (mat) Transition–Defective Mutants inCaenorhabditis elegans

PubMed Central

Golden, Andy; Sadler, Penny L.; Wallenfang, Matthew R.; Schumacher, Jill M.; Hamill, Danielle R.; Bates, Gayle; Bowerman, Bruce; Seydoux, Geraldine; Shakes, Diane C.

2000-01-01

The metaphase to anaphase transition is a critical stage of the eukaryotic cell cycle, and, thus, it is highly regulated. Errors during this transition can lead to chromosome segregation defects and death of the organism. In genetic screens for temperature-sensitive maternal effect embryonic lethal (Mel) mutants, we have identified 32 mutants in the nematode Caenorhabditis elegans in which fertilized embryos arrest as one-cell embryos. In these mutant embryos, the oocyte chromosomes arrest in metaphase of meiosis I without transitioning to anaphase or producing polar bodies. An additional block in M phase exit is evidenced by the failure to form pronuclei and the persistence of phosphohistone H3 and MPM-2 antibody staining. Spermatocyte meiosis is also perturbed; primary spermatocytes arrest in metaphase of meiosis I and fail to produce secondary spermatocytes. Analogous mitotic defects cause M phase delays in mitotic germline proliferation. We have named this class of mutants “mat” for metaphase to anaphase transition defective. These mutants, representing six different complementation groups, all map near genes that encode subunits of the anaphase promoting complex or cyclosome, and, here, we show that one of the genes, emb-27, encodes the C. elegans CDC16 ortholog. PMID:11134076

Novel CLCN7 compound heterozygous mutations in intermediate autosomal recessive osteopetrosis.

PubMed

Okamoto, Nana; Kohmoto, Tomohiro; Naruto, Takuya; Masuda, Kiyoshi; Komori, Takahide; Imoto, Issei

2017-01-01

Osteopetrosis is a heritable disorder of the skeleton that is characterized by increased bone density on radiographs caused by defects in osteoclast formation and function. Mutations in >10 genes are identified as causative for this clinically and genetically heterogeneous disease in humans. We report two novel missense variations in a compound heterozygous state in the CLCN7 gene, detected through targeted exome sequencing, in a 15-year-old Japanese female with intermediate autosomal recessive osteopetrosis.

Fanconi anemia (cross)linked to DNA repair.

PubMed

Niedernhofer, Laura J; Lalai, Astrid S; Hoeijmakers, Jan H J

2005-12-29

Fanconi anemia is characterized by hypersensitivity to DNA interstrand crosslinks (ICLs) and susceptibility to tumor formation. Despite the identification of numerous Fanconi anemia (FANC) genes, the mechanism by which proteins encoded by these genes protect a cell from DNA interstrand crosslinks remains unclear. The recent discovery of two DNA helicases that, when defective, cause Fanconi anemia tips the balance in favor of the direct involvement of the FANC proteins in DNA repair and the bypass of DNA lesions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leshinsky-Silver, E.; Mitochondrial Disease Center, Wolfson Medical Center, Holon; E-mail: leshinsky@wolfson.health.gov.il

Leigh syndrome can result from both nuclear and mitochondrial DNA defects. Mutations in complex V genes of the respiratory chain were considered until recently as the most frequent cause for mitochondrial inherited Leigh syndrome, while gene defects in complex I were related to recessive Leigh syndrome. Recently few reports of mutations in the mitochondrial-encoded complex I subunit genes causing Leigh syndrome have been reported. We describe a 1-month-old baby who acutely deteriorated, with abrupt onset of brainstem dysfunction, due to basal ganglia lesions extending to the brainstem. A muscle biopsy demonstrated complex I deficiency. Subsequent analysis of the mitochondrial genomemore » revealed a homoplastic T10191C mutation in the ND3 gene (in blood and muscle), resulting in a substitution of serine to proline. Hair root analysis revealed a 50% mutant load, reflecting heteroplasmy in early embryonic stages. The mutation was also detected in his mother (5%). Western blot analysis revealed a decrease of the 20 kDa subunit (likely ND6) and of the 30 kDa subunit (NDUFA9), which is probably due to instability attributed to the inability to form subcomplexes with ND3. This is the first description of infantile Leigh syndrome due to a maternally transmitted T10191C substitution in ND3 and not due to a de novo mutation. This mutation is age and tissue dependent and therefore may not be amenable to prenatal testing.« less

Activity-Dependent Dysfunction in Visual and Olfactory Sensory Systems in Mouse Models of Down Syndrome

PubMed Central

Saqran, Lubna; Herrick, Scott P.; Frosch, Matthew P.; Hyman, Bradley T.

2017-01-01

Activity-dependent synaptic plasticity plays a critical role in the refinement of circuitry during postnatal development and may be disrupted in conditions that cause intellectual disability, such as Down syndrome (DS). To test this hypothesis, visual cortical plasticity was assessed in Ts65Dn mice that harbor a chromosomal duplication syntenic to human chromosome 21q. We find that Ts65Dn mice demonstrate a defect in ocular dominance plasticity (ODP) following monocular deprivation. This phenotype is similar to that of transgenic mice that express amyloid precursor protein (APP), which is duplicated in DS and in Ts65DN mice; however, normalizing APP gene copy number in Ts65Dn mice fails to rescue plasticity. Ts1Rhr mice harbor a duplication of the telomeric third of the Ts65Dn-duplicated sequence and demonstrate the same ODP defect, suggesting a gene or genes sufficient to drive the phenotype are located in that smaller duplication. In addition, we find that Ts65Dn mice demonstrate an abnormality in olfactory system connectivity, a defect in the refinement of connections to second-order neurons in the olfactory bulb. Ts1Rhr mice do not demonstrate a defect in glomerular refinement, suggesting that distinct genes or sets of genes underlie visual and olfactory system phenotypes. Importantly, these data suggest that developmental plasticity and connectivity are impaired in sensory systems in DS model mice, that such defects may contribute to functional impairment in DS, and that these phenotypes, present in male and female mice, provide novel means for examining the genetic and molecular bases for neurodevelopmental impairment in model mice in vivo. SIGNIFICANCE STATEMENT Our understanding of the basis for intellectual impairment in Down syndrome is hindered by the large number of genes duplicated in Trisomy 21 and a lack of understanding of the effect of disease pathology on the function of neural circuits in vivo. This work describes early postnatal developmental abnormalities in visual and olfactory sensory systems in Down syndrome model mice, which provide insight into defects in the function of neural circuits in vivo and provide an approach for exploring the genetic and molecular basis for impairment in the disease. In addition, these findings raise the possibility that basic dysfunction in primary sensory circuitry may illustrate mechanisms important for global learning and cognitive impairment in Down syndrome patients. PMID:28899917

Genes for normal sleep and sleep disorders.

PubMed

Tafti, Mehdi; Maret, Stéphanie; Dauvilliers, Yves

2005-01-01

Sleep and wakefulness are complex behaviors that are influenced by many genetic and environmental factors, which are beginning to be discovered. The contribution of genetic components to sleep disorders is also increasingly recognized as important. Point mutations in the prion protein, period 2, and the prepro-hypocretin/orexin gene have been found as the cause of a few sleep disorders but the possibility that other gene defects may contribute to the pathophysiology of major sleep disorders is worth in-depth investigations. However, single gene disorders are rare and most common disorders are complex in terms of their genetic susceptibility, environmental effects, gene-gene, and gene-environment interactions. We review here the current progress in the genetics of normal and pathological sleep.

Dysregulation of the PDGFRA gene causes inflow tract anomalies including TAPVR: integrating evidence from human genetics and model organisms

PubMed Central

Bleyl, Steven B.; Saijoh, Yukio; Bax, Noortje A.M.; Gittenberger-de Groot, Adriana C.; Wisse, Lambertus J.; Chapman, Susan C.; Hunter, Jennifer; Shiratori, Hidetaka; Hamada, Hiroshi; Yamada, Shigehito; Shiota, Kohei; Klewer, Scott E.; Leppert, Mark F.; Schoenwolf, Gary C.

2010-01-01

Total anomalous pulmonary venous return (TAPVR) is a congenital heart defect inherited via complex genetic and/or environmental factors. We report detailed mapping in extended TAPVR kindreds and mutation analysis in TAPVR patients that implicate the PDGFRA gene in the development of TAPVR. Gene expression studies in mouse and chick embryos for both the Pdgfra receptor and its ligand Pdgf-a show temporal and spatial patterns consistent with a role in pulmonary vein (PV) development. We used an in ovo function blocking assay in chick and a conditional knockout approach in mouse to knock down Pdgfra expression in the developing venous pole during the period of PV formation. We observed that loss of PDGFRA function in both organisms causes TAPVR with low penetrance (∼7%) reminiscent of that observed in our human TAPVR kindreds. Intermediate inflow tract anomalies occurred in a higher percentage of embryos (∼30%), suggesting that TAPVR occurs at one end of a spectrum of defects. We show that the anomalous pulmonary venous connection seen in chick and mouse is highly similar to TAPVR discovered in an abnormal early stage embryo from the Kyoto human embryo collection. Whereas the embryology of the normal venous pole and PV is becoming understood, little is known about the embryogenesis or molecular pathogenesis of TAPVR. These models of TAPVR provide important insight into the pathogenesis of PV defects. Taken together, these data from human genetics and animal models support a role for PDGF-signaling in normal PV development, and in the pathogenesis of TAPVR. PMID:20071345

Targeted disruption of FANCC and FANCG in human cancer provides a preclinical model for specific therapeutic options.

PubMed

Gallmeier, Eike; Calhoun, Eric S; Rago, Carlo; Brody, Jonathan R; Cunningham, Steven C; Hucl, Tomas; Gorospe, Myriam; Kohli, Manu; Lengauer, Christoph; Kern, Scott E

2006-06-01

How specifically to treat pancreatic and other cancers harboring Fanconi anemia gene mutations has raised great interest recently, yet preclinical studies have been hampered by the lack of well-controlled human cancer models. We endogenously disrupted FANCC and FANCG in a human adenocarcinoma cell line and determined the impact of these genes on drug sensitivity, irradiation sensitivity, and genome maintenance. FANCC and FANCG disruption abrogated FANCD2 monoubiquitination, confirming an impaired Fanconi anemia pathway function. On treatment with DNA interstrand-cross-linking agents, FANCC and FANCG disruption caused increased clastogenic damage, G2/M arrest, and decreased proliferation. The extent of hypersensitivity varied among agents, with ratios of inhibitory concentration 50% ranging from 2-fold for oxaliplatin to 14-fold for melphalan, a drug infrequently used in solid tumors. No hypersensitivity was observed on gemcitabine, etoposide, 3-aminobenzamide, NU1025, or hydrogen peroxide. FANCC and FANCG disruption also resulted in increased clastogenic damage on irradiation, but only FANCG disruption caused a subsequent decrease in relative survival. Finally, FANCC and FANCG disruption increased spontaneous chromosomal breakage, supporting the role of these genes in genome maintenance and likely explaining why they are mutated in sporadic cancer. Our human cancer cell model provides optimal controls to elucidate fundamental biologic features of individual Fanconi anemia gene defects and facilitates preclinical studies of therapeutic options. The impact of Fanconi gene defects on drug and irradiation sensitivity renders these genes promising targets for a specific, genotype-based therapy for individual cancer patients, providing a strong rationale for clinical trials.

Early-Onset Severe Encephalopathy with Epilepsy: The BRAT1 Gene Should Be Added to the List of Causes.

PubMed

van de Pol, Laura A; Wolf, Nicole I; van Weissenbruch, Mirjam M; Stam, Cornelie J; Weiss, Janneke M; Waisfisz, Quinten; Kevelam, Sietske H; Bugiani, Mariana; van de Kamp, Jiddeke M; van der Knaap, Marjo S

2015-12-01

A variety of pathologies can underlie early-onset severe encephalopathy with epilepsy. To aid the diagnostic process in such patients we present an overview of causes, including the rapidly expanding list of genes involved. When no explanation is found, whole-exome sequencing (WES) can be used in an attempt to identify gene defects in patients suspected to suffer from a genetic form. We describe three siblings, born to consanguineous parents, with a lethal severe epileptic encephalopathy with early-infantile onset, including their magnetic resonance imaging, electroencephalography and, in one case, neuropathological findings. Using WES a homozygous frameshift mutation in the BRAT1 gene, c.638dup p.(Val214Glyfs*189), was identified. We present our cases in the context of all published cases with mutations in the BRAT1 gene and conclude that BRAT1 should be added to the growing list of genes related to early-onset severe encephalopathy with epilepsy. Georg Thieme Verlag KG Stuttgart · New York.

Regulatory interplay of Cockayne syndrome B ATPase and stress-response gene ATF3 following genotoxic stress.

PubMed

Kristensen, Ulrik; Epanchintsev, Alexey; Rauschendorf, Marc-Alexander; Laugel, Vincent; Stevnsner, Tinna; Bohr, Vilhelm A; Coin, Frédéric; Egly, Jean-Marc

2013-06-18

Cockayne syndrome type B ATPase (CSB) belongs to the SwItch/Sucrose nonfermentable family. Its mutations are linked to Cockayne syndrome phenotypes and classically are thought to be caused by defects in transcription-coupled repair, a subtype of DNA repair. Here we show that after UV-C irradiation, immediate early genes such as activating transcription factor 3 (ATF3) are overexpressed. Although the ATF3 target genes, including dihydrofolate reductase (DHFR), were unable to recover RNA synthesis in CSB-deficient cells, transcription was restored rapidly in normal cells. There the synthesis of DHFR mRNA restarts on the arrival of RNA polymerase II and CSB and the subsequent release of ATF3 from its cAMP response element/ATF target site. In CSB-deficient cells ATF3 remains bound to the promoter, thereby preventing the arrival of polymerase II and the restart of transcription. Silencing of ATF3, as well as stable introduction of wild-type CSB, restores RNA synthesis in UV-irradiated CSB cells, suggesting that, in addition to its role in DNA repair, CSB activity likely is involved in the reversal of inhibitory properties on a gene-promoter region. We present strong experimental data supporting our view that the transcriptional defects observed in UV-irradiated CSB cells are largely the result of a permanent transcriptional repression of a certain set of genes in addition to some defect in DNA repair.

Planar cell polarity pathway genes and risk for spina bifida.

PubMed

Wen, Shu; Zhu, Huiping; Lu, Wei; Mitchell, Laura E; Shaw, Gary M; Lammer, Edward J; Finnell, Richard H

2010-02-01

Spina bifida, a neural tube closure defect (NTD) involving the posterior portion of what will ultimately give rise to the spinal cord, is one of the most common and serious birth defects. The etiology of spina bifida is thought to be multi-factorial and involve multiple interacting genes and environmental factors. The causes of this congenital malformation remain largely unknown. However, several candidate genes for spina bifida have been identified in lower vertebrates, including the planar cell polarity (PCP) genes. We used data from a case-control study conducted in California to evaluate the association between variation within several key PCP genes and the risk of spina bifida. The PCP genes included in this study were the human homologs of the Xenopus genes Flamingo, Strabismus, Prickle, Dishevelled, and Scrib, two of the homologs of Xenopus Wnt genes, WNT5A and WNT11, and two of the homologs of Xenopus Frizzled, FZD3 and FZD6. None of the 172 SNPs that were evaluated were significantly associated with spina bifida in any racial/ethnic group after correction for multiple testing. However, several SNPs in the PRICKLE2 gene had unadjusted P-value <0.01. In conclusion, our results, though largely negative, suggest that the PRICKLE2 gene may potentially modify the risk of spina bifida and deserves further investigation. Copyright 2010 Wiley-Liss, Inc.

Paracellular transport in the collecting duct

PubMed Central

Hou, Jianghui

2016-01-01

Purpose of review The paracellular pathway through the tight junction provides an important route for chloride reabsorption in the collecting duct of the kidney. This review describes recent findings of how defects in paracellular chloride permeation pathway may cause kidney diseases and how such a pathway may be regulated to maintain normal chloride homeostasis. Recent findings The tight junction in the collecting duct expresses two important claudin genes – claudin-4 and claudin-8. Transgenic knockout of either claudin gene causes hypotension, hypochloremia, and metabolic alkalosis in experimental animals. The claudin-4 mediated chloride permeability can be regulated by a protease endogenously expressed by the collecting duct cell – Cap1. Cap1 regulates the intercellular interaction of claudin-4 and its membrane stability. KLHL3, previously identified as a causal gene for Gordon’s syndrome, also known as pseudohypoaldosteronism II (PHA-II), directly interacts with claudin-8 and regulates its ubiquitination and degradation. The dominant PHA-II mutation (R528H) in KLHL3 abolishes claudin-8 binding, ubiquitination, and degradation. Summary The paracellular chloride permeation pathway in the kidney is an important but understudied area in nephrology. It plays vital roles in renal salt handling and regulation of extracellular fluid volume and blood pressure. Two claudin proteins – claudin-4 and claudin-8 contribute to the function of this paracellular pathway. Deletion of either claudin protein from the collecting duct causes renal chloride reabsorption defects and low blood pressure. Claudins can be regulated on post-translational levels by several mechanisms involving protease and ubiquitin ligase. Deregulation of claudins may cause human hypertension as exemplified in the Gordon’s syndrome. PMID:27490784

Hypoxia induced DNA damage in children with isolated septal defect and septal defect with great vessel anomaly of heart.

PubMed

G, Vidya; H Y, Suma; Bhat B, Vishnu; Chand, Parkash; Rao K, Ramachandra

2014-04-01

In Congenital Heart Disease (CHD), shunting of blood occurs through the anatomical defects which lead to mixing of oxygenated and deoxygenated blood. Chronic hypoxia which occurs due to the above said mechanism has the potency to cause DNA damage in children with CHD. In chronic hypoxia, there is a liberation of Reactive Oxygen Species (ROS) due to tissue injury as a result of ischemia and induction of hypoxia inducible factor - 1HIF-1 and p53 which in turn activates pro-apoptotic factors leading to alteration in the regulation of pro-apoptotic gene Blc-2 to be involved in causing the DNA damage. The extent of chronic hypoxia and the DNA damage depends on the nature of the anatomical heart defect. Hence, the present case-control study was conducted to find out the DNA damage in children with isolated septal defect and septal defect with great vessel anomaly of heart and to compare the same. The study group was categorized into those with isolated septal defects and septal defects associated with great vessel anomaly based on echo-cardiogram. Age and sex matched healthy children were taken as controls. Single-cell gel electrophoresis - Comet Assay of Alkaline Version was performed conventionally and the comets were analyzed using comet score software. The comet metrics was found to be statistically significant in children with isolated septal defect and septal defect with great vessel anomaly when compared with that of the controls. In addition, comet metrics also showed significantly increased DNA damage among children with septal defects associated with great vessel anomaly when compared to isolated septal defects. The data strongly suggests a linear correlation of severity of the anomaly involved with the degree of DNA damage as evidenced by lesser extent of DNA damage in isolated septal defect and greater in septal defect with great vessel anomaly.

Acute rhabdomyolysis and inflammation.

PubMed

Hamel, Yamina; Mamoune, Asmaa; Mauvais, François-Xavier; Habarou, Florence; Lallement, Laetitia; Romero, Norma Beatriz; Ottolenghi, Chris; de Lonlay, Pascale

2015-07-01

Rhabdomyolysis results from the rapid breakdown of skeletal muscle fibers, which leads to leakage of potentially toxic cellular content into the systemic circulation. Acquired causes by direct injury to the sarcolemma are most frequent. The inherited causes are: i) metabolic with failure of energy production, including mitochondrial fatty acid ß-oxidation defects, LPIN1 mutations, inborn errors of glycogenolysis and glycolysis, more rarely mitochondrial respiratory chain deficiency, purine defects and peroxysomal α-methyl-acyl-CoA-racemase defect (AMACR), ii) structural causes with muscle dystrophies and myopathies, iii) calcium pump disorder with RYR1 gene mutations, iv) inflammatory causes with myositis. Irrespective of the cause of rhabdomyolysis, the pathology follows a common pathway, either by the direct injury to sarcolemma by increased intracellular calcium concentration (acquired causes) or by the failure of energy production (inherited causes), which leads to fiber necrosis. Rhabdomyolysis are frequently precipitated by febrile illness or exercise. These conditions are associated with two events, elevated temperature and high circulating levels of pro-inflammatory mediators such as cytokines and chemokines. To illustrate these points in the context of energy metabolism, protein thermolability and the potential benefits of arginine therapy, we focus on a rare cause of rhabdomyolysis, aldolase A deficiency. In addition, our studies on lipin-1 (LPIN1) deficiency raise the possibility that several diseases involved in rhabdomyolysis implicate pro-inflammatory cytokines and may even represent primarily pro-inflammatory diseases. Thus, not only thermolability of mutant proteins critical for muscle function, but also pro-inflammatory cytokines per se, may lead to metabolic decompensation and rhabdomyolysis.

A-to-I RNA editing promotes developmental stage–specific gene and lncRNA expression

PubMed Central

Goldstein, Boaz; Agranat-Tamir, Lily; Light, Dean; Ben-Naim Zgayer, Orna; Fishman, Alla; Lamm, Ayelet T.

2017-01-01

A-to-I RNA editing is a conserved widespread phenomenon in which adenosine (A) is converted to inosine (I) by adenosine deaminases (ADARs) in double-stranded RNA regions, mainly noncoding. Mutations in ADAR enzymes in Caenorhabditis elegans cause defects in normal development but are not lethal as in human and mouse. Previous studies in C. elegans indicated competition between RNA interference (RNAi) and RNA editing mechanisms, based on the observation that worms that lack both mechanisms do not exhibit defects, in contrast to the developmental defects observed when only RNA editing is absent. To study the effects of RNA editing on gene expression and function, we established a novel screen that enabled us to identify thousands of RNA editing sites in nonrepetitive regions in the genome. These include dozens of genes that are edited at their 3′ UTR region. We found that these genes are mainly germline and neuronal genes, and that they are down-regulated in the absence of ADAR enzymes. Moreover, we discovered that almost half of these genes are edited in a developmental-specific manner, indicating that RNA editing is a highly regulated process. We found that many pseudogenes and other lncRNAs are also extensively down-regulated in the absence of ADARs in the embryo but not in the fourth larval (L4) stage. This down-regulation is not observed upon additional knockout of RNAi. Furthermore, levels of siRNAs aligned to pseudogenes in ADAR mutants are enhanced. Taken together, our results suggest a role for RNA editing in normal growth and development by regulating silencing via RNAi. PMID:28031250

Mutations in Prickle Orthologs Cause Seizures in Flies, Mice, and Humans

PubMed Central

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

A novel form of ciliopathy underlies hyperphagia and obesity in Ankrd26 knockout mice

PubMed Central

Acs, Peter; Bauer, Peter O.; Mayer, Balazs; Bera, Tapan; Macallister, Rhonda; Pastan, Ira

2015-01-01

Human ciliopathies are genetic disorders caused by mutations in genes responsible for the formation and function of primary cilia. Some are associated with hyperphagia and obesity (e.g., Bardet–Biedl Syndrome, Alström Syndrome), but the mechanisms underlying these problems are not fully understood. The human gene ANKRD26 is located on 10p12, a locus that is associated with some forms of hereditary obesity. Previously, we reported that disruption of this gene causes hyperphagia, obesity and gigantism in mice. In the present study, we looked for the mechanisms that induce hyperphagia in the Ankrd26−/− mice and found defects in primary cilia in regions of the central nervous system that control appetite and energy homeostasis. PMID:24633808

A new link between stress response and nucleolar function during pollen development in Arabidopsis mediated by AtREN1 protein.

PubMed

Reňák, David; Gibalová, Antónia; Solcová, Katarzyna; Honys, David

2014-03-01

Heat shock transcription factors (Hsfs) are involved in multiple aspects of stress response and plant growth. However, their role during male gametophyte development is largely unknown, although the generative phase is the most sensitive and critical period in the plant life cycle. Based on a wide screen of T-DNA mutant lines, we identified the atren1 mutation (restricted to nucleolus1) in early male gametophytic gene At1g77570, which has the closest homology to HSFA5 gene, the member of a heat shock transcription factor (HSF) gene family. The mutation causes multiple defects in male gametophyte development in both structure and function. Because the mutation disrupts an early acting (AtREN1) gene, these pollen phenotype abnormalities appear from bicellular pollen stage to pollen maturation. Moreover, the consequent progamic phase is compromised as well as documented by pollen germination defects and limited transmission via male gametophyte. In addition, atren1/- plants are defective in heat stress (HS) response and produce notably higher proportion of aberrant pollen grains. AtREN1 protein is targeted specifically to the nucleolus that, together with the increased size of the nucleolus in atren1 pollen, suggests that it is likely to be involved in ribosomal RNA biogenesis or other nucleolar functions. © 2013 John Wiley & Sons Ltd.

Mg2+ Extrusion from Intestinal Epithelia by CNNM Proteins Is Essential for Gonadogenesis via AMPK-TORC1 Signaling in Caenorhabditis elegans

PubMed Central

Ishii, Tasuku; Funato, Yosuke; Hashizume, Osamu; Yamazaki, Daisuke; Hirata, Yusuke; Nishiwaki, Kiyoji; Kono, Nozomu; Arai, Hiroyuki; Miki, Hiroaki

2016-01-01

Mg2+ serves as an essential cofactor for numerous enzymes and its levels are tightly regulated by various Mg2+ transporters. Here, we analyzed Caenorhabditis elegans strains carrying mutations in genes encoding cyclin M (CNNM) Mg2+ transporters. We isolated inactivating mutants for each of the five Caenorhabditis elegans cnnm family genes, cnnm-1 through cnnm-5. cnnm-1; cnnm-3 double mutant worms showed various phenotypes, among which the sterile phenotype was rescued by supplementing the media with Mg2+. This sterility was caused by a gonadogenesis defect with severely attenuated proliferation of germ cells. Using this gonadogenesis defect as an indicator, we performed genome-wide RNAi screening, to search for genes associated with this phenotype. The results revealed that RNAi-mediated inactivation of several genes restores gonad elongation, including aak-2, which encodes the catalytic subunit of AMP-activated protein kinase (AMPK). We then generated triple mutant worms for cnnm-1; cnnm-3; aak-2 and confirmed that the aak-2 mutation also suppressed the defective gonadal elongation in cnnm-1; cnnm-3 mutant worms. AMPK is activated under low-energy conditions and plays a central role in regulating cellular metabolism to adapt to the energy status of cells. Thus, we provide genetic evidence linking Mg2+ homeostasis to energy metabolism via AMPK. PMID:27564576

Human iPSC-Derived Neural Progenitors Are an Effective Drug Discovery Model for Neurological mtDNA Disorders.

PubMed

Lorenz, Carmen; Lesimple, Pierre; Bukowiecki, Raul; Zink, Annika; Inak, Gizem; Mlody, Barbara; Singh, Manvendra; Semtner, Marcus; Mah, Nancy; Auré, Karine; Leong, Megan; Zabiegalov, Oleksandr; Lyras, Ekaterini-Maria; Pfiffer, Vanessa; Fauler, Beatrix; Eichhorst, Jenny; Wiesner, Burkhard; Huebner, Norbert; Priller, Josef; Mielke, Thorsten; Meierhofer, David; Izsvák, Zsuzsanna; Meier, Jochen C; Bouillaud, Frédéric; Adjaye, James; Schuelke, Markus; Wanker, Erich E; Lombès, Anne; Prigione, Alessandro

2017-05-04

Mitochondrial DNA (mtDNA) mutations frequently cause neurological diseases. Modeling of these defects has been difficult because of the challenges associated with engineering mtDNA. We show here that neural progenitor cells (NPCs) derived from human induced pluripotent stem cells (iPSCs) retain the parental mtDNA profile and exhibit a metabolic switch toward oxidative phosphorylation. NPCs derived in this way from patients carrying a deleterious homoplasmic mutation in the mitochondrial gene MT-ATP6 (m.9185T>C) showed defective ATP production and abnormally high mitochondrial membrane potential (MMP), plus altered calcium homeostasis, which represents a potential cause of neural impairment. High-content screening of FDA-approved drugs using the MMP phenotype highlighted avanafil, which we found was able to partially rescue the calcium defect in patient NPCs and differentiated neurons. Overall, our results show that iPSC-derived NPCs provide an effective model for drug screening to target mtDNA disorders that affect the nervous system. Copyright © 2016 Elsevier Inc. All rights reserved.

Adenovirus-mediated p53 gene delivery inhibits 9L glioma growth in rats.

PubMed

Badie, B; Drazan, K E; Kramar, M H; Shaked, A; Black, K L

1995-06-01

Adenoviral vectors have recently been shown to effectively deliver genes into a variety of tissues. Since these vectors have some advantages over the more extensively investigated retroviruses, we studied the effect of two replication-defective adenovectors bearing human wild type tumor suppressor gene p53 (Adp53) and Escherichia coli beta-galactosidase gene (AdLacZ) on 9L glioma cells. Successful in vitro gene transfer was shown by DNA polymerase chain reaction (PCR), and expression was confirmed by reverse transcriptase RNA PCR and Western blot analyses. Transduction of 9L cells with the Adp53 inhibited cell growth and induced phenotypic changes consistent with cell death at low titers, while AdLacZ caused cytopathic changes only at high titers. Stereotactic injection of AdLacZ (10(7) plaque forming units) into tumor bed stained 25 to 30% of tumor cells at the site of vector delivery. Injection of Adp53 (10(7) plaque forming units), but not AdLacZ (controls), into established 4-day old 9L glioma brain tumors decreased tumor volume by 40% after 14 days. As a step toward gene therapy of brain tumors using replication-defective adenoviruses, these data support the use of tumor suppressor gene transfer for in vivo treatment of whole animal brain tumor models.

BIG: a calossin-like protein required for polar auxin transport in Arabidopsis

PubMed Central

Gil, Pedro; Dewey, Elizabeth; Friml, Jiri; Zhao, Yunde; Snowden, Kimberley C.; Putterill, Jo; Palme, Klaus; Estelle, Mark; Chory, Joanne

2001-01-01

Polar auxin transport is crucial for the regulation of auxin action and required for some light-regulated responses during plant development. We have found that two mutants of Arabidopsis—doc1, which displays altered expression of light-regulated genes, and tir3, known for its reduced auxin transport—have similar defects and define mutations in a single gene that we have renamed BIG. BIG is very similar to the Drosophila gene Calossin/Pushover, a member of a gene family also present in Caenorhabditis elegans and human genomes. The protein encoded by BIG is extraordinary in size, 560 kD, and contains several putative Zn-finger domains. Expression-profiling experiments indicate that altered expression of multiple light-regulated genes in doc1 mutants can be suppressed by elevated levels of auxin caused by overexpression of an auxin biosynthetic gene, suggesting that normal auxin distribution is required to maintain low-level expression of these genes in the dark. Double mutants of tir3 with the auxin mutants pin1, pid, and axr1 display severe defects in auxin-dependent growth of the inflorescence. Chemical inhibitors of auxin transport change the intracellular localization of the auxin efflux carrier PIN1 in doc1/tir3 mutants, supporting the idea that BIG is required for normal auxin efflux. PMID:11485992

Defective ribosome assembly in Shwachman-Diamond syndrome.

PubMed

Wong, Chi C; Traynor, David; Basse, Nicolas; Kay, Robert R; Warren, Alan J

2011-10-20

Shwachman-Diamond syndrome (SDS), a recessive leukemia predisposition disorder characterized by bone marrow failure, exocrine pancreatic insufficiency, skeletal abnormalities and poor growth, is caused by mutations in the highly conserved SBDS gene. Here, we test the hypothesis that defective ribosome biogenesis underlies the pathogenesis of SDS. We create conditional mutants in the essential SBDS ortholog of the ancient eukaryote Dictyostelium discoideum using temperature-sensitive, self-splicing inteins, showing that mutant cells fail to grow at the restrictive temperature because ribosomal subunit joining is markedly impaired. Remarkably, wild type human SBDS complements the growth and ribosome assembly defects in mutant Dictyostelium cells, but disease-associated human SBDS variants are defective. SBDS directly interacts with the GTPase elongation factor-like 1 (EFL1) on nascent 60S subunits in vivo and together they catalyze eviction of the ribosome antiassociation factor eukaryotic initiation factor 6 (eIF6), a prerequisite for the translational activation of ribosomes. Importantly, lymphoblasts from SDS patients harbor a striking defect in ribosomal subunit joining whose magnitude is inversely proportional to the level of SBDS protein. These findings in Dictyostelium and SDS patient cells provide compelling support for the hypothesis that SDS is a ribosomopathy caused by corruption of an essential cytoplasmic step in 60S subunit maturation.

The chicken frizzle feather is due to an a-keratin (KRT75) mutation that causes a defective rachis

USDA-ARS?s Scientific Manuscript database

Feathers have complex forms and are an excellent model to study the development and evolution of morphologies. Existing chicken feather mutants are especially useful for identifying genetic determinants of feather formation. The present study focused on the gene, F, underlying the frizzle feather tr...

Genetics Home Reference: autosomal recessive cerebellar ataxia type 1

MedlinePlus

... defective protein is thought to impair Purkinje cell function and disrupt signaling between neurons in the cerebellum. The loss of brain cells in the cerebellum causes the movement problems characteristic of ARCA1 , but it is unclear how this cell loss is ... Learn more about the gene associated with ARCA1 ...

Essential role for the alpha 1 chain of type VIII collagen in zebrafish notochord formation.

PubMed

Gansner, John M; Gitlin, Jonathan D

2008-12-01

Several zebrafish mutants identified in large-scale forward genetic screens exhibit notochord distortion. We now report the cloning and further characterization of one such mutant, gulliver(m208) (gul(m208)). The notochord defect in gul(m208) mutants is exacerbated under conditions of copper depletion or lysyl oxidase cuproenzyme inhibition that are without a notochord effect on wild-type embryos. The gul(m208) phenotype results from a missense mutation in the gene encoding Col8a1, a lysyl oxidase substrate, and morpholino knockdown of col8a1 recapitulates the notochord distortion observed in gul(m208) mutants. Of interest, the amino acid mutated in gul(m208) Col8a1 is highly conserved, and the equivalent substitution in a closely related human protein, COL10A1, causes Schmid metaphyseal chondrodysplasia. Taken together, the data identify a new protein essential for notochord morphogenesis, extend our understanding of gene-nutrient interactions in early development, and suggest that human mutations in COL8A1 may cause structural birth defects. (c) 2008 Wiley-Liss, Inc.

Inactivation of Bmp4 from the Tbx1 Expression Domain Causes Abnormal Pharyngeal Arch Artery and Cardiac Outflow Tract Remodeling

PubMed Central

Nie, Xuguang; Brown, Christopher B.; Wang, Qin; Jiao, Kai

2011-01-01

Maldevelopment of outflow tract and aortic arch arteries is among the most common forms of human congenital heart diseases. Both Bmp4 and Tbx1 are known to play critical roles during cardiovascular development. Expression of these two genes partially overlaps in pharyngeal arch areas in mouse embryos. In this study, we applied a conditional gene inactivation approach to test the hypothesis that Bmp4 expressed from the Tbx1 expression domain plays a critical role for normal development of outflow tract and pharyngeal arch arteries. We showed that inactivation of Bmp4 from Tbx1-expressing cells leads to the spectrum of deformities resembling the cardiovascular defects observed in human DiGeorge syndrome patients. Inactivation of Bmp4 from the Tbx1 expression domain did not cause patterning defects, but affected remodeling of outflow tract and pharyngeal arch arteries. Our further examination revealed that Bmp4 is required for normal recruitment/differentiation of smooth muscle cells surrounding the PAA4 and survival of outflow tract cushion mesenchymal cells. PMID:21123999

Mutations in SNRPB, encoding components of the core splicing machinery, cause cerebro-costo-mandibular syndrome.

PubMed

Bacrot, Séverine; Doyard, Mathilde; Huber, Céline; Alibeu, Olivier; Feldhahn, Niklas; Lehalle, Daphné; Lacombe, Didier; Marlin, Sandrine; Nitschke, Patrick; Petit, Florence; Vazquez, Marie-Paule; Munnich, Arnold; Cormier-Daire, Valérie

2015-02-01

Cerebro-costo-mandibular syndrome (CCMS) is a developmental disorder characterized by the association of Pierre Robin sequence and posterior rib defects. Exome sequencing and Sanger sequencing in five unrelated CCMS patients revealed five heterozygous variants in the small nuclear ribonucleoprotein polypeptides B and B1 (SNRPB) gene. This gene includes three transcripts, namely transcripts 1 and 2, encoding components of the core spliceosomal machinery (SmB' and SmB) and transcript 3 undergoing nonsense-mediated mRNA decay. All variants were located in the premature termination codon (PTC)-introducing alternative exon of transcript 3. Quantitative RT-PCR analysis revealed a significant increase in transcript 3 levels in leukocytes of CCMS individuals compared to controls. We conclude that CCMS is due to heterozygous mutations in SNRPB, enhancing inclusion of a SNRPB PTC-introducing alternative exon, and show that this developmental disease is caused by defects in the splicing machinery. Our finding confirms the report of SNRPB mutations in CCMS patients by Lynch et al. (2014) and further extends the clinical and molecular observations. © 2014 WILEY PERIODICALS, INC.

Neural Tube Defects

PubMed Central

Greene, Nicholas D.E.; Copp, Andrew J.

2015-01-01

Neural tube defects (NTDs), including spina bifida and anencephaly, are severe birth defects of the central nervous system that originate during embryonic development when the neural tube fails to close completely. Human NTDs are multifactorial, with contributions from both genetic and environmental factors. The genetic basis is not yet well understood, but several nongenetic risk factors have been identified as have possibilities for prevention by maternal folic acid supplementation. Mechanisms underlying neural tube closure and NTDs may be informed by experimental models, which have revealed numerous genes whose abnormal function causes NTDs and have provided details of critical cellular and morphological events whose regulation is essential for closure. Such models also provide an opportunity to investigate potential risk factors and to develop novel preventive therapies. PMID:25032496

Mutations in the human SC4MOL gene encoding a methyl sterol oxidase cause psoriasiform dermatitis, microcephaly, and developmental delay

PubMed Central

He, Miao; Kratz, Lisa E.; Michel, Joshua J.; Vallejo, Abbe N.; Ferris, Laura; Kelley, Richard I.; Hoover, Jacqueline J.; Jukic, Drazen; Gibson, K. Michael; Wolfe, Lynne A.; Ramachandran, Dhanya; Zwick, Michael E.; Vockley, Jerry

2011-01-01

Defects in cholesterol synthesis result in a wide variety of symptoms, from neonatal lethality to the relatively mild dysmorphic features and developmental delay found in individuals with Smith-Lemli-Opitz syndrome. We report here the identification of mutations in sterol-C4-methyl oxidase–like gene (SC4MOL) as the cause of an autosomal recessive syndrome in a human patient with psoriasiform dermatitis, arthralgias, congenital cataracts, microcephaly, and developmental delay. This gene encodes a sterol-C4-methyl oxidase (SMO), which catalyzes demethylation of C4-methylsterols in the cholesterol synthesis pathway. C4-Methylsterols are meiosis-activating sterols (MASs). They exist at high concentrations in the testis and ovary and play roles in meiosis activation. In this study, we found that an accumulation of MASs in the patient led to cell overproliferation in both skin and blood. SMO deficiency also substantially altered immunocyte phenotype and in vitro function. MASs serve as ligands for liver X receptors α and β (LXRα and LXRβ), which are important in regulating not only lipid transport in the epidermis, but also innate and adaptive immunity. Deficiency of SMO represents a biochemical defect in the cholesterol synthesis pathway, the clinical spectrum of which remains to be defined. PMID:21285510

Node and midline defects are associated with left-right development in Delta1 mutant embryos.

PubMed

Przemeck, Gerhard K H; Heinzmann, Ulrich; Beckers, Johannes; Hrabé de Angelis, Martin

2003-01-01

Axes formation is a fundamental process of early embryonic development. In addition to the anteroposterior and dorsoventral axes, the determination of the left-right axis is crucial for the proper morphogenesis of internal organs and is evolutionarily conserved in vertebrates. Genes known to be required for the normal establishment and/or maintenance of left-right asymmetry in vertebrates include, for example, components of the TGF-beta family of intercellular signalling molecules and genes required for node and midline function. We report that Notch signalling, which previously had not been implicated in this morphogenetic process, is required for normal left-right determination in mice. We show, that the loss-of-function of the delta 1 (Dll1) gene causes a situs ambiguous phenotype, including randomisation of the direction of heart looping and embryonic turning. The most probable cause for this left-right defect in Dll1 mutant embryos is a failure in the development of proper midline structures. These originate from the node, which is disrupted and deformed in Dll1 mutant embryos. Based on expression analysis in wild-type and mutant embryos, we suggest a model, in which Notch signalling is required for the proper differentiation of node cells and node morphology.

A neurotransmitter transporter encoded by the Drosophila inebriated gene

PubMed Central

Soehnge, Holly; Huang, Xi; Becker, Marie; Whitley, Penn; Conover, Diana; Stern, Michael

1996-01-01

Behavioral and electrophysiological studies on mutants defective in the Drosophila inebriated (ine) gene demonstrated increased excitability of the motor neuron. In this paper, we describe the cloning and sequence analysis of ine. Mutations in ine were localized on cloned DNA by restriction mapping and restriction fragment length polymorphism (RFLP) mapping of ine mutants. DNA from the ine region was then used to isolate an ine cDNA. In situ hybridization of ine transcripts to developing embryos revealed expression of this gene in several cell types, including the posterior hindgut, Malpighian tubules, anal plate, garland cells, and a subset of cells in the central nervous system. The ine cDNA contains an open reading frame of 658 amino acids with a high degree of sequence similarity to members of the Na+/Cl−-dependent neurotransmitter transporter family. Members of this family catalyze the rapid reuptake of neurotransmitters released into the synapse and thereby play key roles in controlling neuronal function. We conclude that ine mutations cause increased excitability of the Drosophila motor neuron by causing the defective reuptake of the substrate neurotransmitter of the ine transporter and thus overstimulation of the motor neuron by this neurotransmitter. From this observation comes a unique opportunity to perform a genetic dissection of the regulation of excitability of the Drosophila motor neuron. PMID:8917579

New and emerging targeted therapies for cystic fibrosis.

PubMed

Quon, Bradley S; Rowe, Steven M

2016-03-30

Cystic fibrosis (CF) is a monogenic autosomal recessive disorder that affects about 70,000 people worldwide. The clinical manifestations of the disease are caused by defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The discovery of the CFTR gene in 1989 has led to a sophisticated understanding of how thousands of mutations in the CFTR gene affect the structure and function of the CFTR protein. Much progress has been made over the past decade with the development of orally bioavailable small molecule drugs that target defective CFTR proteins caused by specific mutations. Furthermore, there is considerable optimism about the prospect of gene replacement or editing therapies to correct all mutations in cystic fibrosis. The recent approvals of ivacaftor and lumacaftor represent the genesis of a new era of precision medicine in the treatment of this condition. These drugs are having a positive impact on the lives of people with cystic fibrosis and are potentially disease modifying. This review provides an update on advances in our understanding of the structure and function of the CFTR, with a focus on state of the art targeted drugs that are in development. 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.

A nuclear mutation defective in mitochondrial recombination in yeast.

PubMed

Ling, F; Makishima, F; Morishima, N; Shibata, T

1995-08-15

Homologous recombination (crossing over and gene conversion) is generally essential for heritage and DNA repair, and occasionally causes DNA aberrations, in nuclei of eukaryotes. However, little is known about the roles of homologous recombination in the inheritance and stability of mitochondrial DNA which is continuously damaged by reactive oxygen species, by-products of respiration. Here, we report the first example of a nuclear recessive mutation which suggests an essential role for homologous recombination in the stable inheritance of mitochondrial DNA. For the detection of this class of mutants, we devised a novel procedure, 'mitochondrial crossing in haploid', which has enabled us to examine many mutant clones. Using this procedure, we examined mutants of Saccharomyces cerevisiae that showed an elevated UV induction of respiration-deficient mutations. We obtained a mutant that was defective in both the omega-intron homing and Endo.SceI-induced homologous gene conversion. We found that the mutant cells are temperature sensitive in the maintenance of mitochondrial DNA. A tetrad analysis indicated that elevated UV induction of respiration-deficient mutations, recombination deficiency and temperature sensitivity are all caused by a single nuclear mutation (mhr1) on chromosome XII. The pleiotropic characteristics of the mutant suggest an essential role for the MHR1 gene in DNA repair, recombination and the maintenance of DNA in mitochondria.

Genotype-phenotype relationships in human red/green color-vision defects: molecular and psychophysical studies.

PubMed Central

Deeb, S S; Lindsey, D T; Hibiya, Y; Sanocki, E; Winderickx, J; Teller, D Y; Motulsky, A G

1992-01-01

The relationship between the molecular structure of the X-linked red and green visual pigment genes and color-vision phenotype as ascertained by anomaloscopy was studied in 64 color-defective males. The great majority of red-green defects were associated with either the deletion of the green-pigment gene or the formation of 5' red-green hybrid genes or 5' green-red hybrid genes. A rapid PCR-based method allowed detection of hybrid genes, including those undetectable by Southern blot analysis, as well as more precise localization of the fusion points in hybrid genes. Protan color-vision defects appeared always associated with 5' red-green hybrid genes. Carriers of single red-green hybrid genes with fusion in introns 1-4 were protanopes. However, carriers of hybrid genes with red-green fusions in introns 2, 3, or 4 in the presence of additional normal green genes manifested as either protanopes or protanomalous trichromats, with the majority being protanomalous. Deutan defects were associated with green-pigment gene deletions, with 5' green-red hybrid genes, or, rarely, with 5' green-red-green hybrid genes. Complete green-pigment gene deletions or green-red fusions in intron 1 were usually associated with deuteranopia, although we unexpectedly found three carriers of a single red-pigment gene without any green-pigment genes to be deuteranomalous trichromats. All but one of the other deuteranomalous subjects had green-red hybrid genes with intron 1, 2, 3, or 4 fusions, as well as several normal green-pigment genes. The one exception had a grossly normal gene array, presumably with a more subtle mutation. Amino acid differences in exon 5 largely determine whether a hybrid gene will be more redlike or more greenlike in phenotype. Various discrepancies as to severity (dichromacy or trichromacy) remain unexplained but may arise because of variability of expression, postreceptoral variation, or both. When phenotypic color-vision defects exist, the kind of defect (protan or deutan) can be predicted by molecular analysis. Red-green hybrid genes are probably always associated with protan color-vision defects, while the presence of green-red hybrid genes may not always manifest phenotypically with color-vision defects. Four subjects who were found to have 5' green-red hybrid genes in addition to normal red- and green-pigment genes had normal color vision as determined by anomaloscopy. These were discovered among a group of 129 Caucasian males who had been recruited as volunteers for a vision study.(ABSTRACT TRUNCATED AT 400 WORDS) Images Figure 3 PMID:1415215

Systematic profiling of Caenorhabditis elegans locomotive behaviors reveals additional components in G-protein Gαq signaling.

PubMed

Yu, Hui; Aleman-Meza, Boanerges; Gharib, Shahla; Labocha, Marta K; Cronin, Christopher J; Sternberg, Paul W; Zhong, Weiwei

2013-07-16

Genetic screens have been widely applied to uncover genetic mechanisms of movement disorders. However, most screens rely on human observations of qualitative differences. Here we demonstrate the application of an automatic imaging system to conduct a quantitative screen for genes regulating the locomotive behavior in Caenorhabditis elegans. Two hundred twenty-seven neuronal signaling genes with viable homozygous mutants were selected for this study. We tracked and recorded each animal for 4 min and analyzed over 4,400 animals of 239 genotypes to obtain a quantitative, 10-parameter behavioral profile for each genotype. We discovered 87 genes whose inactivation causes movement defects, including 50 genes that had never been associated with locomotive defects. Computational analysis of the high-content behavioral profiles predicted 370 genetic interactions among these genes. Network partition revealed several functional modules regulating locomotive behaviors, including sensory genes that detect environmental conditions, genes that function in multiple types of excitable cells, and genes in the signaling pathway of the G protein Gαq, a protein that is essential for animal life and behavior. We developed quantitative epistasis analysis methods to analyze the locomotive profiles and validated the prediction of the γ isoform of phospholipase C as a component in the Gαq pathway. These results provided a system-level understanding of how neuronal signaling genes coordinate locomotive behaviors. This study also demonstrated the power of quantitative approaches in genetic studies.

Novel CLCN7 compound heterozygous mutations in intermediate autosomal recessive osteopetrosis

PubMed Central

Okamoto, Nana; Kohmoto, Tomohiro; Naruto, Takuya; Masuda, Kiyoshi; Komori, Takahide; Imoto, Issei

2017-01-01

Osteopetrosis is a heritable disorder of the skeleton that is characterized by increased bone density on radiographs caused by defects in osteoclast formation and function. Mutations in >10 genes are identified as causative for this clinically and genetically heterogeneous disease in humans. We report two novel missense variations in a compound heterozygous state in the CLCN7 gene, detected through targeted exome sequencing, in a 15-year-old Japanese female with intermediate autosomal recessive osteopetrosis. PMID:28819563

The Drosophila nuclear lamina protein otefin is required for germline stem cell survival.

PubMed

Barton, Lacy J; Pinto, Belinda S; Wallrath, Lori L; Geyer, Pamela K

2013-06-24

LEM domain (LEM-D) proteins are components of an extensive protein network that assembles beneath the inner nuclear envelope. Defects in LEM-D proteins cause tissue-restricted human diseases associated with altered stem cell homeostasis. Otefin (Ote) is a Drosophila LEM-D protein that is intrinsically required for female germline stem cell (GSC) maintenance. Previous studies linked Ote loss with transcriptional activation of the key differentiation gene bag-of-marbles (bam), leading to the model in which Ote tethers the bam gene to the nuclear periphery for gene silencing. Using genetic and phenotypic analyses of multiple ote(-/-) backgrounds, we obtained evidence that is inconsistent with this model. We show that bam repression is maintained in ote(-/-) GSCs and that germ cell loss persists in ote(-/-), bam(-/-) mutants, together demonstrating that GSC loss is independent of bam transcription. We show that the primary defect in ote(-/-) GSCs is a block of differentiation, which ultimately leads to germ cell death. Copyright © 2013 Elsevier Inc. All rights reserved.

Primordial dwarfism: an update.

PubMed

Alkuraya, Fowzan S

2015-02-01

To review the recent advances in the clinical and molecular characterization of primordial dwarfism, an extreme growth deficiency disorder that has its onset during embryonic development and persists throughout life. The last decade has witnessed an unprecedented acceleration in the discovery of genes mutated in primordial dwarfism, from one gene to more than a dozen genes. These genetic discoveries have confirmed the notion that primordial dwarfism is caused by defects in basic cellular processes, most notably centriolar biology and DNA damage response. Fortunately, the increasing number of reported clinical primordial dwarfism subtypes has been accompanied by more accurate molecular classification. Qualitative defects of centrioles with resulting abnormal mitosis dynamics, reduced proliferation, and increased apoptosis represent the predominant molecular pathogenic mechanism in primordial dwarfism. Impaired DNA damage response is another important mechanism, which we now know is not mutually exclusive to abnormal centrioles. Molecular characterization of primordial dwarfism is helping families by enabling more reproductive choices and may pave the way for the future development of therapeutics.

Human RHOH deficiency causes T cell defects and susceptibility to EV-HPV infections.

PubMed

Crequer, Amandine; Troeger, Anja; Patin, Etienne; Ma, Cindy S; Picard, Capucine; Pedergnana, Vincent; Fieschi, Claire; Lim, Annick; Abhyankar, Avinash; Gineau, Laure; Mueller-Fleckenstein, Ingrid; Schmidt, Monika; Taieb, Alain; Krueger, James; Abel, Laurent; Tangye, Stuart G; Orth, Gérard; Williams, David A; Casanova, Jean-Laurent; Jouanguy, Emmanuelle

2012-09-01

Epidermodysplasia verruciformis (EV) is a rare genetic disorder characterized by increased susceptibility to specific human papillomaviruses, the betapapillomaviruses. These EV-HPVs cause warts and increase the risk of skin carcinomas in otherwise healthy individuals. Inactivating mutations in epidermodysplasia verruciformis 1 (EVER1) or EVER2 have been identified in most, but not all, patients with autosomal recessive EV. We found that 2 young adult siblings presenting with T cell deficiency and various infectious diseases, including persistent EV-HPV infections, were homozygous for a mutation creating a stop codon in the ras homolog gene family member H (RHOH) gene. RHOH encodes an atypical Rho GTPase expressed predominantly in hematopoietic cells. Patients' circulating T cells contained predominantly effector memory T cells, which displayed impaired TCR signaling. Additionally, very few circulating T cells expressed the β7 integrin subunit, which homes T cells to specific tissues. Similarly, Rhoh-null mice exhibited a severe overall T cell defect and abnormally small numbers of circulating β7-positive cells. Expression of the WT, but not of the mutated RHOH, allele in Rhoh-/- hematopoietic stem cells corrected the T cell lymphopenia in mice after bone marrow transplantation. We conclude that RHOH deficiency leads to T cell defects and persistent EV-HPV infections, suggesting that T cells play a role in the pathogenesis of chronic EV-HPV infections.

Immune defects caused by mutations in the ubiquitin system.

PubMed

Etzioni, Amos; Ciechanover, Aaron; Pikarsky, Eli

2017-03-01

The importance of the ubiquitin system in health and disease has been widely recognized in recent decades, with better understanding of the various components of the system and their function. Ubiquitination, which is essential to almost all biological processes in eukaryotes, was also found to play an important role in innate and adaptive immune responses. Thus it is not surprising that mutations in genes coding for components of the ubiquitin system cause immune dysregulation. The first defect in the system was described 30 years ago and is due to mutations in the nuclear factor κB (NF-κB) essential modulator, a key regulator of the NF-κB pathway. With use of novel sequencing techniques, many additional mutations in different genes involved in ubiquitination and related to immune system function were identified. This can be clearly illustrated in mutations in the different activation pathways of NF-κB, which result in aberrations in production of various proinflammatory cytokines. The inherited diseases typically manifest with immunodeficiency, autoimmunity, or autoinflammation. In this perspective we provide a short description of the ubiquitin system, with specific emphasis given to its role in the immune system. The various immunodeficiency conditions identified thus far in association with defective ubiquitination are discussed in more detail. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Anabaena sp. strain PCC 7120 conR contains a LytR-CpsA-Psr domain, is developmentally regulated, and is essential for diazotrophic growth and heterocyst morphogenesis.

PubMed

Mella-Herrera, Rodrigo A; Neunuebel, M Ramona; Golden, James W

2011-03-01

The conR (all0187) gene of the filamentous cyanobacterium Anabaena (Nostoc) sp. strain PCC 7120 is predicted to be part of a family of proteins that contain the LytR-CpsA-Psr domain associated with septum formation and cell wall maintenance. The conR gene was originally misannotated as a transcription regulator. Northern RNA blot analysis showed that conR expression was upregulated 8 h after nitrogen step-down. Fluorescence microscopy of a P(conR)-gfp reporter strain revealed increased GFP fluorescence in proheterocysts and heterocysts beginning 9 h after nitrogen step-down. Insertional inactivation of conR caused a septum-formation defect of vegetative cells grown in nitrate-containing medium. In nitrate-free medium, mutant filaments formed abnormally long heterocysts and were defective for diazotrophic growth. Septum formation between heterocysts and adjacent vegetative cells was abnormal, often with one or both poles of the heterocysts appearing partially open. In a conR mutant, expression of nifH was delayed after nitrogen step-down and nitrogenase activity was approximately 70 % of wild-type activity, indicating that heterocysts of the conR mutant strain are partially functional. We hypothesize that the diazotrophic growth defect is caused by an inability of the heterocysts to transport fixed nitrogen to the neighbouring vegetative cells.

[A case of Leigh syndrome associated with respiratory chain complex I deficiency due to mitochondrial gene 13513G>A mutation].

PubMed

Wei, Xiao-Qiong; Kong, Qing-Peng; Zhang, Yao; Yang, Yan-Ling; Chang, Xing-Zhi; Qi, Yu; Qi, Zhao-Yue; Xiao, Jiang-Xi; Qin, Jiong; Wu, Xi-Ru

2009-05-01

Leigh syndrome is a genetically heterogeneous disease caused by defects in enzymes involved in aerobic energy metabolism and the Krebs', cycle. Mitonchondrial complex I deficiency is a main cause of Leigh syndrome. In this study, a Chinese child with Leigh syndrome caused by 13513G>A mutation was reported. The proband was the first child of his parents. The previously healthy boy presented with generalized epilepsy at 12 years of age. When he visited Peking University First Hospital at 13 years of age, he had subacute loss of vision in two eyes and temporal defect of visual field in the left eye. He walked with a spastic gait. His blood lactate and pyruvate levels were elevated. Muscle biopsy showed mild lipid accumulation in muscle fiber. An electrocardiogram showed incomplete right bundle branch block. Brain magnetic resonance imaging showed bilateral, symmetrical lesions in the basal ganglia, supporting the diagnosis of Leigh syndrome. 13513G>A mutation was identified by gene analysis in the patient, which led to mitochondrial respiratory chain complex I deficiency. Multivitamins and L-carnitine were administered. At present, the patient is 16 years old and has progressive deterioration with significant muscle weakness and body weight loss. He is absent from school. He has no obvious retardation in intelligence. 13513G>A mutation was first identified by gene analysis in Chinese population with Leigh syndrome. This may be helpful in genetic counseling.

A novel regulatory defect in the branched-chain α-keto acid dehydrogenase complex due to a mutation in the PPM1K gene causes a mild variant phenotype of maple syrup urine disease.

PubMed

Oyarzabal, Alfonso; Martínez-Pardo, Mercedes; Merinero, Begoña; Navarrete, Rosa; Desviat, Lourdes R; Ugarte, Magdalena; Rodríguez-Pombo, Pilar

2013-02-01

This article describes a hitherto unreported involvement of the phosphatase PP2Cm, a recently described member of the branched-chain α-keto acid dehydrogenase (BCKDH) complex, in maple syrup urine disease (MSUD). The disease-causing mutation was identified in a patient with a mild variant phenotype, involving a gene not previously associated with MSUD. SNP array-based genotyping showed a copy-neutral homozygous pattern for chromosome 4 compatible with uniparental isodisomy. Mutation analysis of the candidate gene, PPM1K, revealed a homozygous c.417_418delTA change predicted to result in a truncated, unstable protein. No PP2Cm mutant protein was detected in immunocytochemical or Western blot expression analyses. The transient expression of wild-type PPM1K in PP2Cm-deficient fibroblasts recovered 35% of normal BCKDH activity. As PP2Cm has been described essential for cell survival, apoptosis and metabolism, the impact of its deficiency on specific metabolic stress variables was evaluated in PP2Cm-deficient fibroblasts. Increases were seen in ROS levels along with the activation of specific stress-signaling MAP kinases. Similar to that described for the pyruvate dehydrogenase complex, a defect in the regulation of BCKDH caused the aberrant metabolism of its substrate, contributing to the patient's MSUD phenotype--and perhaps others. © 2012 WILEY PERIODICALS, INC.

Disruption of the ndhF1 gene affects Chl fluorescence through state transition in the Cyanobacterium Synechocystis sp. PCC 6803, resulting in apparent high efficiency of photosynthesis.

PubMed

Ogawa, Takako; Harada, Tetsuyuki; Ozaki, Hiroshi; Sonoike, Kintake

2013-07-01

In Synechocystis sp. PCC 6803, the disruption of the ndhF1 gene (slr0844), which encodes a subunit of one of the NDH-1 complexes (NDH-1L complex) serving for respiratory electron transfer, causes the largest change in Chl fluorescence induction kinetics among the kinetics of 750 disruptants searched in the Fluorome, the cyanobacterial Chl fluorescence database. The cause of the explicit phenotype of the ndhF1 disruptant was examined by measurements of the photosynthetic rate, Chl fluorescence and state transition. The results demonstrate that the defects in respiratory electron transfer obviously have great impact on Chl fluorescence in cyanobacteria. The inactivation of NDH-1L complexes involving electron transfer from NDH-1 to plastoquinone (PQ) would result in the oxidation of the PQ pool, leading to the transition to State 1, where the yield of Chl fluorescence is high. Apparently, respiration, although its rate is far lower than that of photosynthesis, could affect Chl fluorescence through the state transition as leverage. The disruption of the ndhF1 gene caused lower oxygen-evolving activity but the estimated electron transport rate from Chl fluorescence measurements was faster in the mutant than in the wild-type cells. The discrepancy could be ascribed to the decreased level of non-photochemical quenching due to state transition. One must be cautious when using the Chl fluorescence parameter to estimate photosynthesis in mutants defective in state transition.

Genes Contributing to Porphyromonas gingivalis Fitness in Abscess and Epithelial Cell Colonization Environments.

PubMed

Miller, Daniel P; Hutcherson, Justin A; Wang, Yan; Nowakowska, Zuzanna M; Potempa, Jan; Yoder-Himes, Deborah R; Scott, David A; Whiteley, Marvin; Lamont, Richard J

2017-01-01

Porphyromonas gingivalis is an important cause of serious periodontal diseases, and is emerging as a pathogen in several systemic conditions including some forms of cancer. Initial colonization by P. gingivalis involves interaction with gingival epithelial cells, and the organism can also access host tissues and spread haematogenously. To better understand the mechanisms underlying these properties, we utilized a highly saturated transposon insertion library of P. gingivalis , and assessed the fitness of mutants during epithelial cell colonization and survival in a murine abscess model by high-throughput sequencing (Tn-Seq). Transposon insertions in many genes previously suspected as contributing to virulence showed significant fitness defects in both screening assays. In addition, a number of genes not previously associated with P. gingivalis virulence were identified as important for fitness. We further examined fitness defects of four such genes by generating defined mutations. Genes encoding a carbamoyl phosphate synthetase, a replication-associated recombination protein, a nitrosative stress responsive HcpR transcription regulator, and RNase Z, a zinc phosphodiesterase, showed a fitness phenotype in epithelial cell colonization and in a competitive abscess infection. This study verifies the importance of several well-characterized putative virulence factors of P. gingivalis and identifies novel fitness determinants of the organism.

Clinical and genetic aspects of primary ciliary dyskinesia/Kartagener syndrome.

PubMed

Leigh, Margaret W; Pittman, Jessica E; Carson, Johnny L; Ferkol, Thomas W; Dell, Sharon D; Davis, Stephanie D; Knowles, Michael R; Zariwala, Maimoona A

2009-07-01

Primary ciliary dyskinesia is a genetically heterogeneous disorder of motile cilia. Most of the disease-causing mutations identified to date involve the heavy (dynein axonemal heavy chain 5) or intermediate(dynein axonemal intermediate chain 1) chain dynein genes in ciliary outer dynein arms, although a few mutations have been noted in other genes. Clinical molecular genetic testing for primary ciliary dyskinesia is available for the most common mutations. The respiratory manifestations of primary ciliary dyskinesia (chronic bronchitis leading to bronchiectasis, chronic rhino-sinusitis, and chronic otitis media)reflect impaired mucociliary clearance owing to defective axonemal structure. Ciliary ultrastructural analysis in most patients (>80%) reveals defective dynein arms, although defects in other axonemal components have also been observed. Approximately 50% of patients with primary ciliary dyskinesia have laterality defects (including situs inversus totalis and, less commonly, heterotaxy, and congenital heart disease),reflecting dysfunction of embryological nodal cilia. Male infertility is common and reflects defects in sperm tail axonemes. Most patients with primary ciliary dyskinesia have a history of neonatal respiratory distress, suggesting that motile cilia play a role in fluid clearance during the transition from a fetal to neonatal lung. Ciliopathies involving sensory cilia, including autosomal dominant or recessive polycystic kidney disease, Bardet-Biedl syndrome, and Alstrom syndrome, may have chronic respiratory symptoms and even bronchiectasis suggesting clinical overlap with primary ciliary dyskinesia.

Functional Defects in Color Vision in Patients With Choroideremia.

PubMed

Jolly, Jasleen K; Groppe, Markus; Birks, Jacqueline; Downes, Susan M; MacLaren, Robert E

2015-10-01

To characterize defects in color vision in patients with choroideremia. Prospective cohort study. Thirty patients with choroideremia (41 eyes) and 10 age-matched male controls (19 eyes) with visual acuity of ≥6/36 attending outpatient clinics in Oxford Eye Hospital underwent color vision testing with the Farnsworth-Munsell 100 hue test, visual acuity testing, and autofluorescence imaging. To exclude changes caused by degeneration of the fovea, a subgroup of 14 patients with a visual acuity ≥6/6 was analyzed. Calculated color vision total error scores were compared between the groups and related to a range of factors using a random-effects model. Mean color vision total error scores were 120 (95% confidence interval [CI] 92, 156) in the ≥6/6 choroideremia group, 206 (95% CI 161, 266) in the <6/6 visual acuity choroideremia group, and 47 (95% CI 32, 69) in the control group. Covariate analysis showed a significant difference in color vision total error score between the groups (P < .001 between each group). Patients with choroideremia have a functional defect in color vision compared with age-matched controls. The color vision defect deteriorates as the degeneration encroaches on the fovea. The presence of an early functional defect in color vision provides a useful biomarker against which to assess successful gene transfer in gene therapy trials. Copyright © 2015 Elsevier Inc. All rights reserved.

Eye Development Genes and Known Syndromes

PubMed Central

Slavotinek, Anne M.

2011-01-01

Anophthalmia and microphthalmia (A/M) are significant eye defects because they can have profound effects on visual acuity. A/M is associated with non-ocular abnormalities in an estimated 33–95% of cases and around 25% of patients have an underlying genetic syndrome that is diagnosable. Syndrome recognition is important for targeted molecular genetic testing, prognosis and for counseling regarding recurrence risks. This review provides clinical and molecular information for several of the commonest syndromes associated with A/M: Anophthalmia-Esophageal-Genital syndrome, caused by SOX2 mutations, Anophthalmia and pituitary abnormalities caused by OTX2 mutations, Matthew-Wood syndrome caused by STRA6 mutations, Oculocardiafaciodental syndrome and Lenz microphthalmia caused by BCOR mutations, Microphthalmia Linear Skin pigmentation syndrome caused by HCCS mutations, Anophthalmia, pituitary abnormalities, polysyndactyly caused by BMP4 mutations and Waardenburg anophthalmia caused by mutations in SMOC1. In addition, we briefly discuss the ocular and extraocular phenotypes associated with several other important eye developmental genes, including GDF6, VSX2, RAX, SHH, SIX6 and PAX6. PMID:22005280

Novel NEK8 Mutations Cause Severe Syndromic Renal Cystic Dysplasia through YAP Dysregulation

PubMed Central

Grampa, Valentina; Odye, Gweltas; Thomas, Sophie; Elkhartoufi, Nadia; Filhol, Emilie; Niel, Olivier; Silbermann, Flora; Lebreton, Corinne; Collardeau-Frachon, Sophie; Rouvet, Isabelle; Alessandri, Jean-Luc; Devisme, Louise; Dieux-Coeslier, Anne; Cordier, Marie-Pierre; Capri, Yline; Khung-Savatovsky, Suonavy; Sigaudy, Sabine; Salomon, Rémi; Antignac, Corinne; Gubler, Marie-Claire; Benmerah, Alexandre; Terzi, Fabiola; Attié-Bitach, Tania; Jeanpierre, Cécile; Saunier, Sophie

2016-01-01

Ciliopathies are a group of genetic multi-systemic disorders related to dysfunction of the primary cilium, a sensory organelle present at the cell surface that regulates key signaling pathways during development and tissue homeostasis. In order to identify novel genes whose mutations would cause severe developmental ciliopathies, >500 patients/fetuses were analyzed by a targeted high throughput sequencing approach allowing exome sequencing of >1200 ciliary genes. NEK8/NPHP9 mutations were identified in five cases with severe overlapping phenotypes including renal cystic dysplasia/hypodysplasia, situs inversus, cardiopathy with hypertrophic septum and bile duct paucity. These cases highlight a genotype-phenotype correlation, with missense and nonsense mutations associated with hypodysplasia and enlarged cystic organs, respectively. Functional analyses of NEK8 mutations in patient fibroblasts and mIMCD3 cells showed that these mutations differentially affect ciliogenesis, proliferation/apoptosis/DNA damage response, as well as epithelial morphogenesis. Notably, missense mutations exacerbated some of the defects due to NEK8 loss of function, highlighting their likely gain-of-function effect. We also showed that NEK8 missense and loss-of-function mutations differentially affect the regulation of the main Hippo signaling effector, YAP, as well as the expression of its target genes in patient fibroblasts and renal cells. YAP imbalance was also observed in enlarged spheroids of Nek8-invalidated renal epithelial cells grown in 3D culture, as well as in cystic kidneys of Jck mice. Moreover, co-injection of nek8 MO with WT or mutated NEK8-GFP RNA in zebrafish embryos led to shortened dorsally curved body axis, similar to embryos injected with human YAP RNA. Finally, treatment with Verteporfin, an inhibitor of YAP transcriptional activity, partially rescued the 3D spheroid defects of Nek8-invalidated cells and the abnormalities of NEK8-overexpressing zebrafish embryos. Altogether, our study demonstrates that NEK8 human mutations cause major organ developmental defects due to altered ciliogenesis and cell differentiation/proliferation through deregulation of the Hippo pathway. PMID:26967905

Primary ciliary dyskinesia caused by homozygous mutation in DNAL1, encoding dynein light chain 1.

PubMed

Mazor, Masha; Alkrinawi, Soliman; Chalifa-Caspi, Vered; Manor, Esther; Sheffield, Val C; Aviram, Micha; Parvari, Ruti

2011-05-13

In primary ciliary dyskinesia (PCD), genetic defects affecting motility of cilia and flagella cause chronic destructive airway disease, randomization of left-right body asymmetry, and, frequently, male infertility. The most frequent defects involve outer and inner dynein arms (ODAs and IDAs) that are large multiprotein complexes responsible for cilia-beat generation and regulation, respectively. Although it has long been suspected that mutations in DNAL1 encoding the ODA light chain1 might cause PCD such mutations were not found. We demonstrate here that a homozygous point mutation in this gene is associated with PCD with absent or markedly shortened ODA. The mutation (NM_031427.3: c.449A>G; p.Asn150Ser) changes the Asn at position150, which is critical for the proper tight turn between the β strand and the α helix of the leucine-rich repeat in the hydrophobic face that connects to the dynein heavy chain. The mutation reduces the stability of the axonemal dynein light chain 1 and damages its interactions with dynein heavy chain and with tubulin. This study adds another important component to understanding the types of mutations that cause PCD and provides clinical information regarding a specific mutation in a gene not yet known to be associated with PCD. Copyright © 2011 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

Distinct effects of tubulin isotype mutations on neurite growth in Caenorhabditis elegans

PubMed Central

Zheng, Chaogu; Diaz-Cuadros, Margarete; Nguyen, Ken C. Q.; Hall, David H.; Chalfie, Martin

2017-01-01

Tubulins, the building block of microtubules (MTs), play a critical role in both supporting and regulating neurite growth. Eukaryotic genomes contain multiple tubulin isotypes, and their missense mutations cause a range of neurodevelopmental defects. Using the Caenorhabditis elegans touch receptor neurons, we analyzed the effects of 67 tubulin missense mutations on neurite growth. Three types of mutations emerged: 1) loss-of-function mutations, which cause mild defects in neurite growth; 2) antimorphic mutations, which map to the GTP binding site and intradimer and interdimer interfaces, significantly reduce MT stability, and cause severe neurite growth defects; and 3) neomorphic mutations, which map to the exterior surface, increase MT stability, and cause ectopic neurite growth. Structure-function analysis reveals a causal relationship between tubulin structure and MT stability. This stability affects neuronal morphogenesis. As part of this analysis, we engineered several disease-associated human tubulin mutations into C. elegans genes and examined their impact on neuronal development at the cellular level. We also discovered an α-tubulin (TBA-7) that appears to destabilize MTs. Loss of TBA-7 led to the formation of hyperstable MTs and the generation of ectopic neurites; the lack of potential sites for polyamination and polyglutamination on TBA-7 may be responsible for this destabilization. PMID:28835377

A review of craniofacial disorders caused by spliceosomal defects.

PubMed

Lehalle, D; Wieczorek, D; Zechi-Ceide, R M; Passos-Bueno, M R; Lyonnet, S; Amiel, J; Gordon, C T

2015-11-01

The spliceosome is a large ribonucleoprotein complex that removes introns from pre-mRNA transcripts. Mutations in EFTUD2, encoding a component of the major spliceosome, have recently been identified as the cause of mandibulofacial dysostosis, Guion-Almeida type (MFDGA), characterized by mandibulofacial dysostosis, microcephaly, external ear malformations and intellectual disability. Mutations in several other genes involved in spliceosomal function or linked aspects of mRNA processing have also recently been identified in human disorders with specific craniofacial malformations: SF3B4 in Nager syndrome, an acrofacial dysostosis (AFD); SNRPB in cerebrocostomandibular syndrome, characterized by Robin sequence and rib defects; EIF4A3 in the AFD Richieri-Costa-Pereira syndrome, characterized by Robin sequence, median mandibular cleft and limb defects; and TXNL4A in Burn-McKeown syndrome, involving specific craniofacial dysmorphisms. Here, we review phenotypic and molecular aspects of these syndromes. Given the apparent sensitivity of craniofacial development to defects in mRNA processing, it is possible that mutations in other proteins involved in spliceosomal function will emerge in the future as causative for related human disorders. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Missense mutation of the COQ2 gene causes defects of bioenergetics and de novo pyrimidine synthesis.

PubMed

López-Martín, José M; Salviati, Leonardo; Trevisson, Eva; Montini, Giovanni; DiMauro, Salvatore; Quinzii, Catarina; Hirano, Michio; Rodriguez-Hernandez, Angeles; Cordero, Mario D; Sánchez-Alcázar, José A; Santos-Ocaña, Carlos; Navas, Plácido

2007-05-01

Coenzyme Q(10) (CoQ(10)) deficiency has been associated with an increasing number of clinical phenotypes that respond to CoQ(10) supplementation. In two siblings with encephalomyopathy, nephropathy and severe CoQ(10) deficiency, a homozygous mutation was identified in the CoQ(10) biosynthesis gene COQ2, encoding polyprenyl-pHB transferase. To confirm the pathogenicity of this mutation, we have demonstrated that human wild-type, but not mutant COQ2, functionally complements COQ2 defective yeast. In addition, an equivalent mutation introduced in the yeast COQ2 gene also decreases both CoQ(6) concentration and growth in respiratory-chain dependent medium. Polyprenyl-pHB transferase activity was 33-45% of controls in COQ2 mutant fibroblasts. CoQ-dependent mitochondrial complexes activities were restored in deficient fibroblasts by CoQ(10) supplementation, and growth rate was restored in these cells by either CoQ(10) or uridine supplementation. This work is the first direct demonstration of the pathogenicity of a COQ2 mutation involved in human disease, and establishes yeast as a useful model to study human CoQ(10) deficiency. Moreover, we demonstrate that CoQ(10) deficiency in addition to the bioenergetics defect also impairs de novo pyrimidine synthesis, which may contribute to the pathogenesis of the disease.

Distinct cerebellar foliation anomalies in a CHD7 haploinsufficient mouse model of CHARGE syndrome.

PubMed

Whittaker, Danielle E; Kasah, Sahrunizam; Donovan, Alex P A; Ellegood, Jacob; Riegman, Kimberley L H; Volk, Holger A; McGonnell, Imelda; Lerch, Jason P; Basson, M Albert

2017-12-01

Mutations in the gene encoding the ATP dependent chromatin-remodeling factor, CHD7 are the major cause of CHARGE (Coloboma, Heart defects, Atresia of the choanae, Retarded growth and development, Genital-urinary anomalies, and Ear defects) syndrome. Neurodevelopmental defects and a range of neurological signs have been identified in individuals with CHARGE syndrome, including developmental delay, lack of coordination, intellectual disability, and autistic traits. We previously identified cerebellar vermis hypoplasia and abnormal cerebellar foliation in individuals with CHARGE syndrome. Here, we report mild cerebellar hypoplasia and distinct cerebellar foliation anomalies in a Chd7 haploinsufficient mouse model. We describe specific alterations in the precise spatio-temporal sequence of fissure formation during perinatal cerebellar development responsible for these foliation anomalies. The altered cerebellar foliation pattern in Chd7 haploinsufficient mice show some similarities to those reported in mice with altered Engrailed, Fgf8 or Zic1 gene expression and we propose that mutations or polymorphisms in these genes may modify the cerebellar phenotype in CHARGE syndrome. Our findings in a mouse model of CHARGE syndrome indicate that a careful analysis of cerebellar foliation may be warranted in patients with CHARGE syndrome, particularly in patients with cerebellar hypoplasia and developmental delay. © 2017 The Authors. American Journal of Medical Genetics Part C Published by Wiley Periodicals, Inc.

The Fanconi anemia DNA repair pathway: structural and functional insights into a complex disorder.

PubMed

Walden, Helen; Deans, Andrew J

2014-01-01

Mutations in any of at least sixteen FANC genes (FANCA-Q) cause Fanconi anemia, a disorder characterized by sensitivity to DNA interstrand crosslinking agents. The clinical features of cytopenia, developmental defects, and tumor predisposition are similar in each group, suggesting that the gene products participate in a common pathway. The Fanconi anemia DNA repair pathway consists of an anchor complex that recognizes damage caused by interstrand crosslinks, a multisubunit ubiquitin ligase that monoubiquitinates two substrates, and several downstream repair proteins including nucleases and homologous recombination enzymes. We review progress in the use of structural and biochemical approaches to understanding how each FANC protein functions in this pathway.

Pathophysiological consequences and benefits of HFE mutations: 20 years of research

PubMed Central

Hollerer, Ina; Bachmann, André; Muckenthaler, Martina U.

2017-01-01

Mutations in the HFE (hemochromatosis) gene cause hereditary hemochromatosis, an iron overload disorder that is hallmarked by excessive accumulation of iron in parenchymal organs. The HFE mutation p.Cys282Tyr is pathologically most relevant and occurs in the Caucasian population with a carrier frequency of up to 1 in 8 in specific European regions. Despite this high prevalence, the mutation causes a clinically relevant phenotype only in a minority of cases. In this review, we summarize historical facts and recent research findings about hereditary hemochromatosis, and outline the pathological consequences of the associated gene defects. In addition, we discuss potential advantages of HFE mutations in asymptomatic carriers. PMID:28280078

Defective insulin secretion in hepatocyte nuclear factor 1alpha-deficient mice.

PubMed Central

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

Luna, a Drosophila KLF6/KLF7, Is Maternally Required for Synchronized Nuclear and Centrosome Cycles in the Preblastoderm Embryo

PubMed Central

Weber, Ursula; Rodriguez, Estefania; Martignetti, John; Mlodzik, Marek

2014-01-01

Krüppel like factors (KLFs) are conserved transcription factors that have been implicated in many developmental processes including differentiation, organ patterning, or regulation of stem cell pluripotency. We report the generation and analysis of loss-of-function mutants of Drosophila Klf6/7, the luna gene. We demonstrate that luna mutants are associated with very early embryonic defects prior to cellularization at the syncytial stage and cause DNA separation defects during the rapid mitotic cycles resulting in un-coupled DNA and centrosome cycles. These defects manifest themselves, both in animals that are maternally homozygous and heterozygous mutant. Surprisingly, luna is only required during the syncytial stages and not later in development, suggesting that the DNA segregation defect is linked to centrosomes, since centrosomes are dispensable for later cell divisions. PMID:24915236

Probing Conformational Rescue Induced by a Chemical Corrector of F508del-Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Mutant*

PubMed Central

Yu, Wilson; Chiaw, Patrick Kim; Bear, Christine E.

2011-01-01

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that cause loss of function of the CFTR channel on the apical surface of epithelial cells. The major CF-causing mutation, F508del-CFTR, is misfolded, retained in the endoplasmic reticulum, and degraded. Small molecule corrector compounds have been identified using high throughput screens, which partially rescue the trafficking defect of F508del-CFTR, allowing a fraction of the mutant protein to escape endoplasmic reticulum retention and traffic to the plasma membrane, where it exhibits partial function as a cAMP-regulated chloride channel. A subset of such corrector compounds binds directly to the mutant protein, prompting the hypothesis that they rescue the biosynthetic defect by inducing improved protein conformation. We tested this hypothesis directly by evaluating the consequences of a corrector compound on the conformation of each nucleotide binding domain (NBD) in the context of the full-length mutant protein in limited proteolytic digest studies. Interestingly, we found that VRT-325 was capable of partially restoring compactness in NBD1. However, VRT-325 had no detectable effect on the conformation of the second half of the molecule. In comparison, ablation of the di-arginine sequence, R553XR555 (F508del-KXK-CFTR), modified protease susceptibility of NBD1, NBD2, and the full-length protein. Singly, each intervention led to a partial correction of the processing defect. Together, these interventions restored processing of F508del-CFTR to near wild type. Importantly, however, a defect in NBD1 conformation persisted, as did a defect in channel activation after the combined interventions. Importantly, this defect in channel activation can be fully corrected by the addition of the potentiator, VX-770. PMID:21602569

Loss of MSH2 and MSH6 due to heterozygous germline defects in MSH3 and MSH6.

PubMed

Morak, Monika; Käsbauer, Sarah; Kerscher, Martina; Laner, Andreas; Nissen, Anke M; Benet-Pagès, Anna; Schackert, Hans K; Keller, Gisela; Massdorf, Trisari; Holinski-Feder, Elke

2017-10-01

Lynch Syndrome (LS) is the most common dominantly inherited colorectal cancer (CRC) predisposition and is caused by a heterozygous germline defect in one of the DNA mismatch repair (MMR) genes MLH1, MSH2, MSH6, or PMS2. High microsatellite instability (MSI-H) and loss of MMR protein expression in tumours reflecting a defective MMR are indicators for LS, as well as a positive family history of early onset CRC. MSH2 and MSH6 form a major functional heterodimer, and MSH3 is an alternative binding partner for MSH2. So far, the role of germline MSH3 variants remains unclear, as to our knowledge heterozygous truncating variants are not regarded causative for LS, but were detected in patients with CRC, and recently biallelic MSH3 defects have been identified in two patients with adenomatous polyposis. By gene screening we investigated the role of MSH3 in 11 LS patients with truncating MSH6 germline variants and an unexplained MSH2 protein loss in their corresponding MSI-H tumours. We report the first two LS patients harbouring heterozygous germline variants c.1035del and c.2732T>G in MSH3 coincidentally with truncating variants in MSH6. In the patient with truncating germline variants in MSH3 and MSH6, two additional somatic second hits in both genes abrogate all binding partners for the MSH2 protein which might subsequently be degraded. The clinical relevance of MSH3 germline variants is currently under re-evaluation, and heterozygous MSH3 defects alone do not seem to induce a LS phenotype, but might aggravate the MSH6 phenotype in affected family members.

CRISPR-Cas9 genome engineering: Treating inherited retinal degeneration.

PubMed

Burnight, Erin R; Giacalone, Joseph C; Cooke, Jessica A; Thompson, Jessica R; Bohrer, Laura R; Chirco, Kathleen R; Drack, Arlene V; Fingert, John H; Worthington, Kristan S; Wiley, Luke A; Mullins, Robert F; Stone, Edwin M; Tucker, Budd A

2018-03-22

Gene correction is a valuable strategy for treating inherited retinal degenerative diseases, a major cause of irreversible blindness worldwide. Single gene defects cause the majority of these retinal dystrophies. Gene augmentation holds great promise if delivered early in the course of the disease, however, many patients carry mutations in genes too large to be packaged into adeno-associated viral vectors and some, when overexpressed via heterologous promoters, induce retinal toxicity. In addition to the aforementioned challenges, some patients have sustained significant photoreceptor cell loss at the time of diagnosis, rendering gene replacement therapy insufficient to treat the disease. These patients will require cell replacement to restore useful vision. Fortunately, the advent of induced pluripotent stem cell and CRISPR-Cas9 gene editing technologies affords researchers and clinicians a powerful means by which to develop strategies to treat patients with inherited retinal dystrophies. In this review we will discuss the current developments in CRISPR-Cas9 gene editing in vivo in animal models and in vitro in patient-derived cells to study and treat inherited retinal degenerative diseases. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pancreas-specific deletion of mouse Gata4 and Gata6 causes pancreatic agenesis

PubMed Central

Xuan, Shouhong; Borok, Matthew J.; Decker, Kimberly J.; Battle, Michele A.; Duncan, Stephen A.; Hale, Michael A.; Macdonald, Raymond J.; Sussel, Lori

2012-01-01

Pancreatic agenesis is a human disorder caused by defects in pancreas development. To date, only a few genes have been linked to pancreatic agenesis in humans, with mutations in pancreatic and duodenal homeobox 1 (PDX1) and pancreas-specific transcription factor 1a (PTF1A) reported in only 5 families with described cases. Recently, mutations in GATA6 have been identified in a large percentage of human cases, and a GATA4 mutant allele has been implicated in a single case. In the mouse, Gata4 and Gata6 are expressed in several endoderm-derived tissues, including the pancreas. To analyze the functions of GATA4 and/or GATA6 during mouse pancreatic development, we generated pancreas-specific deletions of Gata4 and Gata6. Surprisingly, loss of either Gata4 or Gata6 in the pancreas resulted in only mild pancreatic defects, which resolved postnatally. However, simultaneous deletion of both Gata4 and Gata6 in the pancreas caused severe pancreatic agenesis due to disruption of pancreatic progenitor cell proliferation, defects in branching morphogenesis, and a subsequent failure to induce the differentiation of progenitor cells expressing carboxypeptidase A1 (CPA1) and neurogenin 3 (NEUROG3). These studies address the conserved and nonconserved mechanisms underlying GATA4 and GATA6 function during pancreas development and provide a new mouse model to characterize the underlying developmental defects associated with pancreatic agenesis. PMID:23006325

Epigenetic control of learning and memory in Drosophila by Tip60 HAT action.

PubMed

Xu, Songjun; Wilf, Rona; Menon, Trisha; Panikker, Priyalakshmi; Sarthi, Jessica; Elefant, Felice

2014-12-01

Disruption of epigenetic gene control mechanisms in the brain causes significant cognitive impairment that is a debilitating hallmark of most neurodegenerative disorders, including Alzheimer's disease (AD). Histone acetylation is one of the best characterized of these epigenetic mechanisms that is critical for regulating learning- and memory- associated gene expression profiles, yet the specific histone acetyltransferases (HATs) that mediate these effects have yet to be fully characterized. Here, we investigate an epigenetic role for the HAT Tip60 in learning and memory formation using the Drosophila CNS mushroom body (MB) as a well-characterized cognition model. We show that Tip60 is endogenously expressed in the Kenyon cells, the intrinsic neurons of the MB, and in the MB axonal lobes. Targeted loss of Tip60 HAT activity in the MB causes thinner and shorter axonal lobes while increasing Tip60 HAT levels cause no morphological defects. Functional consequences of both loss and gain of Tip60 HAT levels in the MB are evidenced by defects in immediate-recall memory. Our ChIP-Seq analysis reveals that Tip60 target genes are enriched for functions in cognitive processes, and, accordingly, key genes representing these pathways are misregulated in the Tip60 HAT mutant fly brain. Remarkably, we find that both learning and immediate-recall memory deficits that occur under AD-associated, amyloid precursor protein (APP)-induced neurodegenerative conditions can be effectively rescued by increasing Tip60 HAT levels specifically in the MB. Together, our findings uncover an epigenetic transcriptional regulatory role for Tip60 in cognitive function and highlight the potential of HAT activators as a therapeutic option for neurodegenerative disorders. Copyright © 2014 by the Genetics Society of America.

Conditional ablation of the choroideremia gene causes age-related changes in mouse retinal pigment epithelium.

PubMed

Wavre-Shapton, Silène T; Tolmachova, Tanya; Lopes da Silva, Mafalda; da Silva, Mafalda Lopes; Futter, Clare E; Seabra, Miguel C

2013-01-01

The retinal pigment epithelium (RPE) is a pigmented monolayer of cells lying between the photoreceptors and a layer of fenestrated capillaries, the choriocapillaris. Choroideremia (CHM) is an X-linked progressive degeneration of these three layers caused by the loss of function of Rab Escort protein-1 (REP1). REP1 is involved in the prenylation of Rab proteins, key regulators of membrane trafficking. To study the pathological consequences of chronic disruption of membrane traffic in the RPE we used a cell type-specific knock-out mouse model of the disease, where the Chm/Rep1 gene is deleted only in pigmented cells (Chm(Flox), Tyr-Cre+). Transmission electron microscopy (TEM) was used to quantitate the melanosome distribution in the RPE and immunofluorescent staining of rhodopsin was used to quantitate phagocytosed rod outer segments in retinal sections. The ultrastructure of the RPE and Bruch's membrane at different ages was characterised by TEM to analyse age-related changes occurring as a result of defects in membrane traffic pathways. Chm/Rep1 gene knockout in RPE cells resulted in reduced numbers of melanosomes in the apical processes and delayed phagosome degradation. In addition, the RPE accumulated pathological changes at 5-6 months of age similar to those observed in 2-year old controls. These included the intracellular accumulation of lipofuscin-containing deposits, disorganised basal infoldings and the extracellular accumulation of basal laminar and basal linear deposits. The phenotype of the Chm(Flox), Tyr-Cre+ mice suggests that loss of the Chm/Rep1 gene causes premature accumulation of features of aging in the RPE. Furthermore, the striking similarities between the present observations and some of the phenotypes reported in age-related macular degeneration (AMD) suggest that membrane traffic defects may contribute to the pathogenesis of AMD.

An siRNA-based functional genomics screen for the identification of regulators of ciliogenesis and ciliopathy genes

PubMed Central

Racher, Hilary; Phelps, Ian G.; Toedt, Grischa; Kennedy, Julie; Wunderlich, Kirsten A.; Sorusch, Nasrin; Abdelhamed, Zakia A.; Natarajan, Subaashini; Herridge, Warren; van Reeuwijk, Jeroen; Horn, Nicola; Boldt, Karsten; Parry, David A.; Letteboer, Stef J.F.; Roosing, Susanne; Adams, Matthew; Bell, Sandra M.; Bond, Jacquelyn; Higgins, Julie; Morrison, Ewan E.; Tomlinson, Darren C.; Slaats, Gisela G.; van Dam, Teunis J. P.; Huang, Lijia; Kessler, Kristin; Giessl, Andreas; Logan, Clare V.; Boyle, Evan A.; Shendure, Jay; Anazi, Shamsa; Aldahmesh, Mohammed; Al Hazzaa, Selwa; Hegele, Robert A.; Ober, Carole; Frosk, Patrick; Mhanni, Aizeddin A.; Chodirker, Bernard N.; Chudley, Albert E.; Lamont, Ryan; Bernier, Francois P.; Beaulieu, Chandree L.; Gordon, Paul; Pon, Richard T.; Donahue, Clem; Barkovich, A. James; Wolf, Louis; Toomes, Carmel; Thiel, Christian T.; Boycott, Kym M.; McKibbin, Martin; Inglehearn, Chris F.; Stewart, Fiona; Omran, Heymut; Huynen, Martijn A.; Sergouniotis, Panagiotis I.; Alkuraya, Fowzan S.; Parboosingh, Jillian S.; Innes, A Micheil; Willoughby, Colin E.; Giles, Rachel H.; Webster, Andrew R.; Ueffing, Marius; Blacque, Oliver; Gleeson, Joseph G.; Wolfrum, Uwe; Beales, Philip L.; Gibson, Toby

2015-01-01

Defects in primary cilium biogenesis underlie the ciliopathies, a growing group of genetic disorders. We describe a whole genome siRNA-based reverse genetics screen for defects in biogenesis and/or maintenance of the primary cilium, obtaining a global resource. We identify 112 candidate ciliogenesis and ciliopathy genes, including 44 components of the ubiquitin-proteasome system, 12 G-protein-coupled receptors, and three pre-mRNA processing factors (PRPF6, PRPF8 and PRPF31) mutated in autosomal dominant retinitis pigmentosa. The PRPFs localise to the connecting cilium, and PRPF8- and PRPF31-mutated cells have ciliary defects. Combining the screen with exome sequencing data identified recessive mutations in PIBF1/CEP90 and C21orf2/LRRC76 as causes of the ciliopathies Joubert and Jeune syndromes. Biochemical approaches place C21orf2 within key ciliopathy-associated protein modules, offering an explanation for the skeletal and retinal involvement observed in individuals with C21orf2-variants. Our global, unbiased approaches provide insights into ciliogenesis complexity and identify roles for unanticipated pathways in human genetic disease. PMID:26167768

Genetic aspects of hypothalamic and pituitary gland development.

PubMed

McCabe, Mark J; Dattani, Mehul T

2014-01-01

Hypothalamo-pituitary development during embryogenesis is a highly complex process involving the interaction of a network of spatiotemporally regulated signaling molecules and transcription factors. Mutations in any of the genes encoding these components can lead to congenital hypopituitarism, which is often associated with a wide spectrum of defects affecting craniofacial/midline development. In turn, these defects can be incompatible with life, or lead to disorders encompassing holoprosencephaly (HPE) and cleft palate, and septo-optic dysplasia (SOD). In recent years, there has been increasing evidence of an overlapping genotype between this spectrum of disorders and Kallmann syndrome (KS), defined as the association of hypogonadotropic hypogonadism (HH) and anosmia. This is consistent with the known phenotypic overlap between these disorders and opens a new avenue of identifying novel genetic causes of the hypopituitarism spectrum. This chapter reviews the genetic and molecular events leading to the successful development of the hypothalamo-pituitary axis during embryogenesis, and focuses on genes in which variations/mutations occur, leading to congenital hypopituitarism and associated defects. © 2014 Elsevier B.V. All rights reserved.

Effects of strain and age on hepatic gene expression profiles in murine models of HFE-associated hereditary hemochromatosis.

PubMed

Lee, Seung-Min; Loguinov, Alexandre; Fleming, Robert E; Vulpe, Christopher D

2015-01-01

Hereditary hemochromatosis is an iron overload disorder most commonly caused by a defect in the HFE gene. While the genetic defect is highly prevalent, the majority of individuals do not develop clinically significant iron overload, suggesting the importance of genetic modifiers. Murine hfe knockout models have demonstrated that strain background has a strong effect on the severity of iron loading. We noted that hepatic iron loading in hfe-/- mice occurs primarily over the first postnatal weeks (loading phase) followed by a timeframe of relatively static iron concentrations (plateau phase). We thus evaluated the effects of background strain and of age on hepatic gene expression in Hfe knockout mice (hfe-/-). Hepatic gene expression profiles were examined using cDNA microarrays in 4- and 8-week-old hfe-/- and wild-type mice on two different genetic backgrounds, C57BL/6J (C57) and AKR/J (AKR). Genes differentially regulated in all hfe-/- mice groups, compared with wild-type mice, including those involved in cell survival, stress and damage responses and lipid metabolism. AKR strain-specific changes in lipid metabolism genes and C57 strain-specific changes in cell adhesion and extracellular matrix protein genes were detected in hfe-/- mice. Mouse strain and age are each significantly associated with hepatic gene expression profiles in hfe-/- mice. These affects may underlie or reflect differences in iron loading in these mice.

Hereditary cancer genes are highly susceptible to splicing mutations

PubMed Central

Soemedi, Rachel; Maguire, Samantha; Murray, Michael F.; Monaghan, Sean F.

2018-01-01

Substitutions that disrupt pre-mRNA splicing are a common cause of genetic disease. On average, 13.4% of all hereditary disease alleles are classified as splicing mutations mapping to the canonical 5′ and 3′ splice sites. However, splicing mutations present in exons and deeper intronic positions are vastly underreported. A recent re-analysis of coding mutations in exon 10 of the Lynch Syndrome gene, MLH1, revealed an extremely high rate (77%) of mutations that lead to defective splicing. This finding is confirmed by extending the sampling to five other exons in the MLH1 gene. Further analysis suggests a more general phenomenon of defective splicing driving Lynch Syndrome. Of the 36 mutations tested, 11 disrupted splicing. Furthermore, analyzing past reports suggest that MLH1 mutations in canonical splice sites also occupy a much higher fraction (36%) of total mutations than expected. When performing a comprehensive analysis of splicing mutations in human disease genes, we found that three main causal genes of Lynch Syndrome, MLH1, MSH2, and PMS2, belonged to a class of 86 disease genes which are enriched for splicing mutations. Other cancer genes were also enriched in the 86 susceptible genes. The enrichment of splicing mutations in hereditary cancers strongly argues for additional priority in interpreting clinical sequencing data in relation to cancer and splicing. PMID:29505604

Genetics, gene expression and bioinformatics of the pituitary gland.

PubMed

Davis, Shannon W; Potok, Mary Anne; Brinkmeier, Michelle L; Carninci, Piero; Lyons, Robert H; MacDonald, James W; Fleming, Michelle T; Mortensen, Amanda H; Egashira, Noboru; Ghosh, Debashis; Steel, Karen P; Osamura, Robert Y; Hayashizaki, Yoshihide; Camper, Sally A

2009-04-01

Genetic cases of congenital pituitary hormone deficiency are common and many are caused by transcription factor defects. Mouse models with orthologous mutations are invaluable for uncovering the molecular mechanisms that lead to problems in organ development and typical patient characteristics. We are using mutant mice defective in the transcription factors PROP1 and POU1F1 for gene expression profiling to identify target genes for these critical transcription factors and candidates for cases of pituitary hormone deficiency of unknown aetiology. These studies reveal critical roles for Wnt signalling pathways, including the TCF/LEF transcription factors and interacting proteins of the groucho family, bone morphogenetic protein antagonists and targets of notch signalling. Current studies are investigating the roles of novel homeobox genes and pathways that regulate the transition from proliferation to differentiation, cell adhesion and cell migration. Pituitary adenomas are a common human health problem, yet most cases are sporadic, necessitating alternative approaches to traditional Mendelian genetic studies. Mouse models of adenoma formation offer the opportunity for gene expression profiling during progressive stages of hyperplasia, adenoma and tumorigenesis. This approach holds promise for the identification of relevant pathways and candidate genes as risk factors for adenoma formation, understanding mechanisms of progression, and identifying drug targets and clinically relevant biomarkers. Copyright 2009 S. Karger AG, Basel.

Genetics, Gene Expression and Bioinformatics of the Pituitary Gland

PubMed Central

Davis, Shannon W; Potok, Mary Anne; Brinkmeier, Michelle L; Carninci, Piero; Lyons, Robert H; MacDonald, James W.; Fleming, Michelle T; Mortensen, Amanda H; Egashira, Noboru; Ghosh, Debashis; Steel, Karen P.; Osamura, Robert Y; Hayashizaki, Yoshihide; Camper, Sally A

2011-01-01

Genetic cases of congenital pituitary hormone deficiency are common and many are caused by transcription factor defects. Mouse models with orthologous mutations are invaluable for uncovering the molecular mechanisms that lead to problems in organ development and typical patient characteristics. We are using mutant mice defective in the transcription factors PROP1 and POU1F1 for gene expression profiling to identify target genes for these critical transcription factors and candidates for cases of pituitary hormone deficiency of unknown etiology. These studies reveal critical roles for Wnt signalling pathways including the TCF/LEF transcription factors and interacting proteins of the groucho family, bone morphogenetic proteins antagonists, and targets of notch signalling. Current studies are investigating roles of novel homeobox genes and pathways that regulate the transition from proliferation to differentiation, cell adhesion and cell migration. Pituitary adenomas are a common human health problem, yet most cases are sporadic, necessitating alternative approaches to traditional Mendelian genetic studies. Mouse models of adenoma formation offer the opportunity for gene expression profiling during progressive stages of hyperplasia, adenoma and tumorigenesis. This approach holds promise for identification of relevant pathways and candidate genes as risk factors for adenoma formation, understanding mechanisms of progression, and identifying drug targets and clinically relevant biomarkers. PMID:19407506

Towards β-globin gene-targeting with integrase-defective lentiviral vectors.

PubMed

Inanlou, Davoud Nouri; Yakhchali, Bagher; Khanahmad, Hossein; Gardaneh, Mossa; Movassagh, Hesam; Cohan, Reza Ahangari; Ardestani, Mehdi Shafiee; Mahdian, Reza; Zeinali, Sirous

2010-11-01

We have developed an integrase-defective lentiviral (LV) vector in combination with a gene-targeting approach for gene therapy of β-thalassemia. The β-globin gene-targeting construct has two homologous stems including sequence upstream and downstream of the β-globin gene, a β-globin gene positioned between hygromycin and neomycin resistant genes and a herpes simplex virus type 1 thymidine kinase (HSVtk) suicide gene. Utilization of integrase-defective LV as a vector for the β-globin gene increased the number of selected clones relative to non-viral methods. This method represents an important step toward the ultimate goal of a clinical gene therapy for β-thalassemia.

[Toxic effect of trichloroethylene on liver cells with CYP3A4 gene defect].

PubMed

Liao, R Y; Liu, S

2016-06-20

To investigate the toxic effect of trichloroethylene on liver cells with CYP3A4 gene defect. The normal human liver cells (L02 cells) and liver cells with CYP3A4 gene defect were exposed to trichloroethylene at different doses (0.0, 0.4, 0.8, 1.6, 3.2, and 6.4 mmol/L). CCK8 assay and RT-qPCR were used to measure cell viability and changes in the expression of apoptosis genes and oncogenes. After being exposed to trichloroethylene at doses of 1.6, 3.2, and 6.4 mmol/L, the liver cells with CYP3A4 gene defect showed significantly higher cell viability than L02 cells (0.91±0.06/0.89±0.05/0.85±0.07 vs 0.80±0.04/0.73±0.06/0.67±0.07, P<0.05). The L02 cells in the 0.8~3.2 mmol/L trichloroethylene groups showed significant increases in the expression of the apoptosis genes caspase-3, caspase-8, and caspase-9 (P<0.05) , as well as the oncogenes c-myc, c-fos, and k-ras (P<0.05). Compared with the L02 cells, the cells with CYP3A4 gene defect showed significant reductions in the expression of the apoptosis genes caspase-3, caspase-8, and caspase-9 and the oncogenes c-myc, c-fos, and k-ras (P<0.05). Trichloroethylene exposure has a less effect on the expression of apoptosis genes and oncogenes in liver cells with CYP3A4 gene defect than in normal human liver cells, suggesting that CYP3A4 gene defect reduces the inductive effect of trichloroethylene on apoptosis genes and oncogenes.

High-throughput, pooled sequencing identifies mutations in NUBPL and FOXRED1 in human complex I deficiency

PubMed Central

Calvo, Sarah E; Tucker, Elena J; Compton, Alison G; Kirby, Denise M; Crawford, Gabriel; Burtt, Noel P; Rivas, Manuel A; Guiducci, Candace; Bruno, Damien L; Goldberger, Olga A; Redman, Michelle C; Wiltshire, Esko; Wilson, Callum J; Altshuler, David; Gabriel, Stacey B; Daly, Mark J; Thorburn, David R; Mootha, Vamsi K

2010-01-01

Discovering the molecular basis of mitochondrial respiratory chain disease is challenging given the large number of both mitochondrial and nuclear genes involved. We report a strategy of focused candidate gene prediction, high-throughput sequencing, and experimental validation to uncover the molecular basis of mitochondrial complex I (CI) disorders. We created five pools of DNA from a cohort of 103 patients and then performed deep sequencing of 103 candidate genes to spotlight 151 rare variants predicted to impact protein function. We used confirmatory experiments to establish genetic diagnoses in 22% of previously unsolved cases, and discovered that defects in NUBPL and FOXRED1 can cause CI deficiency. Our study illustrates how large-scale sequencing, coupled with functional prediction and experimental validation, can reveal novel disease-causing mutations in individual patients. PMID:20818383

The seed dormancy defect of Arabidopsis mutants lacking the transcript elongation factor TFIIS is caused by reduced expression of the DOG1 gene.

PubMed

Mortensen, Simon A; Grasser, Klaus D

2014-01-03

TFIIS is a transcript elongation factor that facilitates transcription by RNA polymerase II, as it assists the enzyme to bypass blocks to mRNA synthesis. Previously, we have reported that Arabidopsis plants lacking TFIIS exhibit reduced seed dormancy. Among the genes differentially expressed in tfIIs seeds, the DOG1 gene was identified that is a known QTL for seed dormancy. Here we have analysed plants that overexpress TFIIS in wild type background, or that harbour an additional copy of DOG1 in tfIIs mutant background. These experiments demonstrate that the down-regulation of DOG1 expression causes the seed dormancy phenotype of tfIIs mutants. Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Effect of different ecological conditions on secondary metabolite production and gene expression in two mycotoxigenic plant pathogen Fusarium species: F. verticillioides and F. equiseti

USDA-ARS?s Scientific Manuscript database

The genus Fusarium includes many species that are plant pathogens and many produce harmful secondary metabolites including fumonisins and trichothecenes. These mycotoxins can cause disease in animals and have been associated with cancers and birth defects in humans. Many factors influence the produc...

A-to-I RNA editing promotes developmental stage-specific gene and lncRNA expression.

PubMed

Goldstein, Boaz; Agranat-Tamir, Lily; Light, Dean; Ben-Naim Zgayer, Orna; Fishman, Alla; Lamm, Ayelet T

2017-03-01

A-to-I RNA editing is a conserved widespread phenomenon in which adenosine (A) is converted to inosine (I) by adenosine deaminases (ADARs) in double-stranded RNA regions, mainly noncoding. Mutations in ADAR enzymes in Caenorhabditis elegans cause defects in normal development but are not lethal as in human and mouse. Previous studies in C. elegans indicated competition between RNA interference (RNAi) and RNA editing mechanisms, based on the observation that worms that lack both mechanisms do not exhibit defects, in contrast to the developmental defects observed when only RNA editing is absent. To study the effects of RNA editing on gene expression and function, we established a novel screen that enabled us to identify thousands of RNA editing sites in nonrepetitive regions in the genome. These include dozens of genes that are edited at their 3' UTR region. We found that these genes are mainly germline and neuronal genes, and that they are down-regulated in the absence of ADAR enzymes. Moreover, we discovered that almost half of these genes are edited in a developmental-specific manner, indicating that RNA editing is a highly regulated process. We found that many pseudogenes and other lncRNAs are also extensively down-regulated in the absence of ADARs in the embryo but not in the fourth larval (L4) stage. This down-regulation is not observed upon additional knockout of RNAi. Furthermore, levels of siRNAs aligned to pseudogenes in ADAR mutants are enhanced. Taken together, our results suggest a role for RNA editing in normal growth and development by regulating silencing via RNAi. © 2017 Goldstein et al.; Published by Cold Spring Harbor Laboratory Press.

Bartter and Gitelman syndromes: Spectrum of clinical manifestations caused by different mutations

PubMed Central

Al Shibli, Amar; Narchi, Hassib

2015-01-01

Bartter and Gitelman syndromes (BS and GS) are inherited disorders resulting in defects in renal tubular handling of sodium, potassium and chloride. Previously considered as genotypic and phenotypic heterogeneous diseases, recent evidence suggests that they constitute a spectrum of disease caused by different genetic mutations with the molecular defects of chloride reabsorption originating at different sites of the nephron in each condition. Although they share some characteristic metabolic abnormalities such as hypokalemia, metabolic alkalosis, hyperplasia of the juxtaglomerular apparatus with hyperreninemia, hyperaldosteronism, the clinical and laboratory manifestations may not always allow distinction between them. Diuretics tests, measuring the changes in urinary fractional excretion of chloride from baseline after administration of either hydrochlorothiazide or furosemide show very little change (< 2.3%) in the fractional excretion of chloride from baseline in GS when compared with BS, except when BS is associated with KCNJ1 mutations where a good response to both diuretics exists. The diuretic test is not recommended for infants or young children with suspected BS because of a higher risk of volume depletion in such children. Clinical symptoms and biochemical markers of GS and classic form of BS (type III) may overlap and thus genetic analysis may specify the real cause of symptoms. However, although genetic analysis is available, its use remains limited because of limited availability, large gene dimensions, lack of hot-spot mutations, heavy workup time and costs involved. Furthermore, considerable overlap exists between the different genotypes and phenotypes. Although BS and GS usually have distinct presentations and are associated with specific gene mutations, there remains considerable overlap between their phenotypes and genotypes. Thus, they are better described as a spectrum of clinical manifestations caused by different gene mutations. PMID:26140272

Duplications of BHLHA9 are associated with ectrodactyly and tibia hemimelia inherited in non-Mendelian fashion.

PubMed

Klopocki, Eva; Lohan, Silke; Doelken, Sandra C; Stricker, Sigmar; Ockeloen, Charlotte W; Soares Thiele de Aguiar, Renata; Lezirovitz, Karina; Mingroni Netto, Regina Celia; Jamsheer, Aleksander; Shah, Hitesh; Kurth, Ingo; Habenicht, Rolf; Warman, Matthew; Devriendt, Koenraad; Kordass, Ulrike; Hempel, Maja; Rajab, Anna; Mäkitie, Outi; Naveed, Mohammed; Radhakrishna, Uppala; Antonarakis, Stylianos E; Horn, Denise; Mundlos, Stefan

2012-02-01

Split-hand/foot malformation (SHFM)-also known as ectrodactyly-is a congenital disorder characterised by severe malformations of the distal limbs affecting the central rays of hands and/or feet. A distinct entity termed SHFLD presents with SHFM and long bone deficiency. Mouse models suggest that a defect of the central apical ectodermal ridge leads to the phenotype. Although six different loci/mutations (SHFM1-6) have been associated with SHFM, the underlying cause in a large number of cases is still unresolved. High resolution array comparative genomic hybridisation (CGH) was performed in patients with SHFLD to detect copy number changes. Candidate genes were further evaluated for expression and function during limb development by whole mount in situ hybridisation and morpholino knock-down experiments. Array CGH showed microduplications on chromosome 17p13.3, a locus previously associated with SHFLD. Detailed analysis of 17 families revealed that this copy number variation serves as a susceptibility factor for a highly variable phenotype with reduced penetrance, particularly in females. Compared to other known causes for SHFLD 17p duplications appear to be the most frequent cause of SHFLD. A ~11.8 kb minimal critical region was identified encompassing a single gene, BHLHA9, a putative basic loop helix transcription factor. Whole mount in situ hybridisation showed expression restricted to the limb bud mesenchyme underlying the apical ectodermal ridge in mouse and zebrafish embryos. Knock down of bhlha9 in zebrafish resulted in shortening of the pectoral fins. Genomic duplications encompassing BHLHA9 are associated with SHFLD and non-Mendelian inheritance characterised by a high degree of non-penetrance with sex bias. Knock-down of bhlha9 in zebrafish causes severe reduction defects of the pectoral fin, indicating a role for this gene in limb development.

The severe hypercholesterolemia phenotype: clinical diagnosis, management, and emerging therapies.

PubMed

Sniderman, Allan D; Tsimikas, Sotirios; Fazio, Sergio

2014-05-20

The severe hypercholesterolemia phenotype includes all patients with marked elevation of low-density lipoprotein cholesterol (LDL-C) levels. The most common cause is autosomal dominant hypercholesterolemia, an inherited disorder caused by mutations either in LDL receptor, apolipoprotein B (APOB), or proprotein convertase subtilisin kexin type 9 (PCSK9) genes. However, it is now known that many subjects with severe inherited hypercholesterolemia have no defects in these genes. These cases are caused either by mutations in genes yet to be identified or are consequences of polygenic, epigenetic, or acquired defects. Because the clinical consequences of extreme hypercholesterolemia are the same no matter the cause, the focus should be on the identification of subjects with severe hypercholesterolemia, followed by phenotypic screening of family members. Genetic screening is not necessary to diagnose or initiate treatment for the severe hypercholesterolemia phenotype. Management of severe hypercholesterolemia is based on risk factor modification and use of multiple lipid-lowering medications. Lipoprotein apheresis is indicated for coronary artery disease (CAD) patients taking maximally tolerated therapy and with LDL-C levels >200 mg/dl (>300 mg/dl if without CAD). A microsomal triglyceride transfer protein inhibitor and an antisense oligonucleotide against APOB have recently been approved for use in subjects with clinically diagnosed homozygous familial hypercholesterolemia. PCSK9 inhibitors, currently in phase II and III trials, lower LDL-C up to an additional 70% in the setting of maximally tolerated medical therapy and have the potential to reduce LDL-C to <70 mg/dl in most patients. Early identification of affected individuals and aggressive treatment should significantly reduce the burden of cardiovascular disease in society. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Deregulation of Fas ligand expression as a novel cause of autoimmune lymphoproliferative syndrome-like disease.

PubMed

Nabhani, Schafiq; Ginzel, Sebastian; Miskin, Hagit; Revel-Vilk, Shoshana; Harlev, Dan; Fleckenstein, Bernhard; Hönscheid, Andrea; Oommen, Prasad T; Kuhlen, Michaela; Thiele, Ralf; Laws, Hans-Jürgen; Borkhardt, Arndt; Stepensky, Polina; Fischer, Ute

2015-09-01

Autoimmune lymphoproliferative syndrome is frequently caused by mutations in genes involved in the Fas death receptor pathway, but for 20-30% of patients the genetic defect is unknown. We observed that treatment of healthy T cells with interleukin-12 induces upregulation of Fas ligand and Fas ligand-dependent apoptosis. Consistently, interleukin-12 could not induce apoptosis in Fas ligand-deficient T cells from patients with autoimmune lymphoproliferative syndrome. We hypothesized that defects in the interleukin-12 signaling pathway may cause a similar phenotype as that caused by mutations of the Fas ligand gene. To test this, we analyzed 20 patients with autoimmune lymphoproliferative syndrome of unknown cause by whole-exome sequencing. We identified a homozygous nonsense mutation (c.698G>A, p.R212*) in the interleukin-12/interleukin-23 receptor-component IL12RB1 in one of these patients. The mutation led to IL12RB1 protein truncation and loss of cell surface expression. Interleukin-12 and -23 signaling was completely abrogated as demonstrated by deficient STAT4 phosphorylation and interferon γ production. Interleukin-12-mediated expression of membrane-bound and soluble Fas ligand was lacking and basal expression was much lower than in healthy controls. The patient presented with the classical symptoms of autoimmune lymphoproliferative syndrome: chronic non-malignant, non-infectious lymphadenopathy, splenomegaly, hepatomegaly, elevated numbers of double-negative T cells, autoimmune cytopenias, and increased levels of vitamin B12 and interleukin-10. Sanger sequencing and whole-exome sequencing excluded the presence of germline or somatic mutations in genes known to be associated with the autoimmune lymphoproliferative syndrome. Our data suggest that deficient regulation of Fas ligand expression by regulators such as the interleukin-12 signaling pathway may be an alternative cause of autoimmune lymphoproliferative syndrome-like disease. Copyright© Ferrata Storti Foundation.

Linkage of Usher syndrome type I gene (USH1B) to the long arm of chromosome 11.

PubMed

Kimberling, W J; Möller, C G; Davenport, S; Priluck, I A; Beighton, P H; Greenberg, J; Reardon, W; Weston, M D; Kenyon, J B; Grunkemeyer, J A

1992-12-01

Usher syndrome is the most commonly recognized cause of combined visual and hearing loss in technologically developed countries. There are several different types and all are inherited in an autosomal recessive manner. There may be as many as five different genes responsible for at least two closely related phenotypes. The nature of the gene defects is unknown, and positional cloning strategies are being employed to identify the genes. This is a report of the localization of one gene for Usher syndrome type I to chromosome 11q, probably distal to marker D11S527. Another USH1 gene had been previously localized to chromosome 14q, and this second localization establishes the existence of a new and independent locus for Usher syndrome.

Cerebrovascular defects in Foxc1 mutants correlate with aberrant WNT and VEGF-A pathways downstream of retinoic acid from the meninges

PubMed Central

Mishra, Swati; Choe, Youngshik; Pleasure, Samuel J.; Siegenthaler, Julie A.

2016-01-01

Growth and maturation of the cerebrovasculature is a vital event in neocortical development however mechanisms that control cerebrovascular development remain poorly understood. Mutations in or deletions that include the FOXC1 gene are associated with congenital cerebrovascular anomalies and increased stroke risk in patients. Foxc1 mutant mice display severe cerebrovascular hemorrhage at late gestational ages. While these data demonstrate Foxc1 is required for cerebrovascular development, its broad expression in the brain vasculature combined with Foxc1 mutant’s complex developmental defects have made it difficult to pinpoint its function(s). Using global and conditional Foxc1 mutants, we find 1) significant cerebrovascular growth defects precede cerebral hemorrhage and 2) expression of Foxc1 in neural crest-derived meninges and brain pericytes, though not endothelial cells, is required for normal cerebrovascular development. We provide evidence that reduced levels of meninges-derived retinoic acid (RA), caused by defects in meninges formation in Foxc1 mutants, is a major contributing factor to the cerebrovascular growth defects in Foxc1 mutants. We provide data that suggests that meninges-derived RA ensures adequate growth of the neocortical vasculature via regulating expression of WNT pathway proteins and neural progenitor derived-VEGF-A. Our findings offer the first evidence for a role of the meninges in brain vascular development and provide new insight into potential causes of cerebrovascular defects in patients with FOXC1 mutations. PMID:27671872

Cerebrovascular defects in Foxc1 mutants correlate with aberrant WNT and VEGF-A pathways downstream of retinoic acid from the meninges.

PubMed

Mishra, Swati; Choe, Youngshik; Pleasure, Samuel J; Siegenthaler, Julie A

2016-12-01

Growth and maturation of the cerebrovasculature is a vital event in neocortical development however mechanisms that control cerebrovascular development remain poorly understood. Mutations in or deletions that include the FOXC1 gene are associated with congenital cerebrovascular anomalies and increased stroke risk in patients. Foxc1 mutant mice display severe cerebrovascular hemorrhage at late gestational ages. While these data demonstrate Foxc1 is required for cerebrovascular development, its broad expression in the brain vasculature combined with Foxc1 mutant's complex developmental defects have made it difficult to pinpoint its function(s). Using global and conditional Foxc1 mutants, we find 1) significant cerebrovascular growth defects precede cerebral hemorrhage and 2) expression of Foxc1 in neural crest-derived meninges and brain pericytes, though not endothelial cells, is required for normal cerebrovascular development. We provide evidence that reduced levels of meninges-derived retinoic acid (RA), caused by defects in meninges formation in Foxc1 mutants, is a major contributing factor to the cerebrovascular growth defects in Foxc1 mutants. We provide data that suggests that meninges-derived RA ensures adequate growth of the neocortical vasculature via regulating expression of WNT pathway proteins and neural progenitor derived-VEGF-A. Our findings offer the first evidence for a role of the meninges in brain vascular development and provide new insight into potential causes of cerebrovascular defects in patients with FOXC1 mutations. Copyright © 2016 Elsevier Inc. All rights reserved.

A screen to identify Drosophila genes required for integrin-mediated adhesion.

PubMed Central

Walsh, E P; Brown, N H

1998-01-01

Drosophila integrins have essential adhesive roles during development, including adhesion between the two wing surfaces. Most position-specific integrin mutations cause lethality, and clones of homozygous mutant cells in the wing do not adhere to the apposing surface, causing blisters. We have used FLP-FRT induced mitotic recombination to generate clones of randomly induced mutations in the F1 generation and screened for mutations that cause wing blisters. This phenotype is highly selective, since only 14 lethal complementation groups were identified in screens of the five major chromosome arms. Of the loci identified, 3 are PS integrin genes, 2 are blistered and bloated, and the remaining 9 appear to be newly characterized loci. All 11 nonintegrin loci are required on both sides of the wing, in contrast to integrin alpha subunit genes. Mutations in 8 loci only disrupt adhesion in the wing, similar to integrin mutations, while mutations in the 3 other loci cause additional wing defects. Mutations in 4 loci, like the strongest integrin mutations, cause a "tail-up" embryonic lethal phenotype, and mutant alleles of 1 of these loci strongly enhance an integrin mutation. Thus several of these loci are good candidates for genes encoding cytoplasmic proteins required for integrin function. PMID:9755209

Pancreas and gallbladder agenesis in a newborn with semilobar holoprosencephaly, a case report.

PubMed

Hilbrands, Robert; Keymolen, Kathelijn; Michotte, Alex; Marichal, Miriam; Cools, Filip; Goossens, Anieta; Veld, Peter In't; De Schepper, Jean; Hattersley, Andrew; Heimberg, Harry

2017-05-19

Pancreatic agenesis is an extremely rare cause of neonatal diabetes mellitus and has enabled the discovery of several key transcription factors essential for normal pancreas and beta cell development. We report a case of a Caucasian female with complete pancreatic agenesis occurring together with semilobar holoprosencephaly (HPE), a more common brain developmental disorder. Clinical findings were later confirmed by autopsy, which also identified agenesis of the gallbladder. Although the sequences of a selected set of genes related to pancreas agenesis or HPE were wild-type, the patient's phenotype suggests a genetic defect that emerges early in embryonic development of brain, gallbladder and pancreas. Developmental defects of the pancreas and brain can occur together. Identifying the genetic defect may identify a novel key regulator in beta cell development.

Sf3b4-depleted Xenopus embryos: a model to study the pathogenesis of craniofacial defects in Nager syndrome

PubMed Central

Devotta, Arun; Juraver-Geslin, Hugo; Gonzalez, Jose Antonio; Hong, Chang-Soo; Saint-Jeannet, Jean-Pierre

2016-01-01

Mandibulofacial dysostosis (MFD) is a human developmental disorder characterized by defects of the facial bones. It is the second most frequent craniofacial malformation after cleft lip and palate. Nager syndrome combines many features of MFD with a variety of limb defects. Mutations in SF3B4 (splicing factor 3b, subunit 4) gene, which encodes a component of the pre-mRNA spliceosomal complex, were recently identified as a cause for Nager syndrome, accounting for 60% of affected individuals. Nothing is known about the cellular pathogenesis underlying Nager type MFD. Here we describe the first animal model for Nager syndrome, generated by knocking down Sf3b4 function in Xenopus laevis embryos, using morpholino antisense oligonucleotides. Our results indicate that Sf3b4-depleted embryos show reduced expression of the neural crest genes sox10, snail2 and twist at the neural plate border, associated with a broadening of the neural plate. This phenotype can be rescued by injection of wild-type human SF3B4 mRNA but not by mRNAs carrying mutations that cause Nager syndrome. At the tailbud stage, morphant embryos had decreased sox10 and tfap2a expression in the pharyngeal arches, indicative of a reduced number of neural crest cells. Later in development, Sf3b4-depleted tadpoles exhibited hypoplasia of neural crest-derived craniofacial cartilages, phenocopying aspects of the craniofacial skeletal defects seen in Nager syndrome patients. With this animal model we are now poised to gain important insights into the etiology and pathogenesis of Nager type MFD, and to identify the molecular targets of Sf3b4. PMID:26874011

Efficient Multiple Genome Modifications Induced by the crRNAs, tracrRNA and Cas9 Protein Complex in Zebrafish

PubMed Central

Ohga, Rie; Ota, Satoshi; Kawahara, Atsuo

2015-01-01

The type II clustered regularly interspaced short palindromic repeats (CRISPR) associated with Cas9 endonuclease (CRISPR/Cas9) has become a powerful genetic tool for understanding the function of a gene of interest. In zebrafish, the injection of Cas9 mRNA and guide-RNA (gRNA), which are prepared using an in vitro transcription system, efficiently induce DNA double-strand breaks (DSBs) at the targeted genomic locus. Because gRNA was originally constructed by fusing two short RNAs CRISPR RNA (crRNA) and trans-activating crRNA (tracrRNA), we examined the effect of synthetic crRNAs and tracrRNA with Cas9 mRNA or Cas9 protein on the genome editing activity. We previously reported that the disruption of tyrosinase (tyr) by tyr-gRNA/Cas9 mRNA causes a retinal pigment defect, whereas the disruption of spns2 by spns2-gRNA1/Cas9 mRNA leads to a cardiac progenitor migration defect in zebrafish. Here, we found that the injection of spns2-crRNA1, tyr-crRNA and tracrRNA with Cas9 mRNA or Cas9 protein simultaneously caused a migration defect in cardiac progenitors and a pigment defect in retinal epithelial cells. A time course analysis demonstrated that the injection of crRNAs and tracrRNA with Cas9 protein rapidly induced genome modifications compared with the injection of crRNAs and tracrRNA with Cas9 mRNA. We further show that the crRNA-tracrRNA-Cas9 protein complex is functional for the visualization of endogenous gene expression; therefore, this is a very powerful, ready-to-use system in zebrafish. PMID:26010089

Mutations in KEOPS-complex genes cause nephrotic syndrome with primary microcephaly.

PubMed

Braun, Daniela A; Rao, Jia; Mollet, Geraldine; Schapiro, David; Daugeron, Marie-Claire; Tan, Weizhen; Gribouval, Olivier; Boyer, Olivia; Revy, Patrick; Jobst-Schwan, Tilman; Schmidt, Johanna Magdalena; Lawson, Jennifer A; Schanze, Denny; Ashraf, Shazia; Ullmann, Jeremy F P; Hoogstraten, Charlotte A; Boddaert, Nathalie; Collinet, Bruno; Martin, Gaëlle; Liger, Dominique; Lovric, Svjetlana; Furlano, Monica; Guerrera, I Chiara; Sanchez-Ferras, Oraly; Hu, Jennifer F; Boschat, Anne-Claire; Sanquer, Sylvia; Menten, Björn; Vergult, Sarah; De Rocker, Nina; Airik, Merlin; Hermle, Tobias; Shril, Shirlee; Widmeier, Eugen; Gee, Heon Yung; Choi, Won-Il; Sadowski, Carolin E; Pabst, Werner L; Warejko, Jillian K; Daga, Ankana; Basta, Tamara; Matejas, Verena; Scharmann, Karin; Kienast, Sandra D; Behnam, Babak; Beeson, Brendan; Begtrup, Amber; Bruce, Malcolm; Ch'ng, Gaik-Siew; Lin, Shuan-Pei; Chang, Jui-Hsing; Chen, Chao-Huei; Cho, Megan T; Gaffney, Patrick M; Gipson, Patrick E; Hsu, Chyong-Hsin; Kari, Jameela A; Ke, Yu-Yuan; Kiraly-Borri, Cathy; Lai, Wai-Ming; Lemyre, Emmanuelle; Littlejohn, Rebecca Okashah; Masri, Amira; Moghtaderi, Mastaneh; Nakamura, Kazuyuki; Ozaltin, Fatih; Praet, Marleen; Prasad, Chitra; Prytula, Agnieszka; Roeder, Elizabeth R; Rump, Patrick; Schnur, Rhonda E; Shiihara, Takashi; Sinha, Manish D; Soliman, Neveen A; Soulami, Kenza; Sweetser, David A; Tsai, Wen-Hui; Tsai, Jeng-Daw; Topaloglu, Rezan; Vester, Udo; Viskochil, David H; Vatanavicharn, Nithiwat; Waxler, Jessica L; Wierenga, Klaas J; Wolf, Matthias T F; Wong, Sik-Nin; Leidel, Sebastian A; Truglio, Gessica; Dedon, Peter C; Poduri, Annapurna; Mane, Shrikant; Lifton, Richard P; Bouchard, Maxime; Kannu, Peter; Chitayat, David; Magen, Daniella; Callewaert, Bert; van Tilbeurgh, Herman; Zenker, Martin; Antignac, Corinne; Hildebrandt, Friedhelm

2017-10-01

Galloway-Mowat syndrome (GAMOS) is an autosomal-recessive disease characterized by the combination of early-onset nephrotic syndrome (SRNS) and microcephaly with brain anomalies. Here we identified recessive mutations in OSGEP, TP53RK, TPRKB, and LAGE3, genes encoding the four subunits of the KEOPS complex, in 37 individuals from 32 families with GAMOS. CRISPR-Cas9 knockout in zebrafish and mice recapitulated the human phenotype of primary microcephaly and resulted in early lethality. Knockdown of OSGEP, TP53RK, or TPRKB inhibited cell proliferation, which human mutations did not rescue. Furthermore, knockdown of these genes impaired protein translation, caused endoplasmic reticulum stress, activated DNA-damage-response signaling, and ultimately induced apoptosis. Knockdown of OSGEP or TP53RK induced defects in the actin cytoskeleton and decreased the migration rate of human podocytes, an established intermediate phenotype of SRNS. We thus identified four new monogenic causes of GAMOS, describe a link between KEOPS function and human disease, and delineate potential pathogenic mechanisms.

Evidence of a bigenomic regulation of mitochondrial gene expression by thyroid hormone during rat brain development.

PubMed

Sinha, Rohit Anthony; Pathak, Amrita; Mohan, Vishwa; Babu, Satish; Pal, Amit; Khare, Drirh; Godbole, Madan M

2010-07-02

Hypothyroidism during early mammalian brain development is associated with decreased expression of various mitochondrial encoded genes along with evidence for mitochondrial dysfunction. However, in-spite of the similarities between neurological disorders caused by perinatal hypothyroidism and those caused by various genetic mitochondrial defects we still do not know as to how thyroid hormone (TH) regulates mitochondrial transcription during development and whether this regulation by TH is nuclear mediated or through mitochondrial TH receptors? We here in rat cerebellum show that hypothyroidism causes reduction in expression of nuclear encoded genes controlling mitochondrial biogenesis like PGC-1alpha, NRF-1alpha and Tfam. Also, we for the first time demonstrate a mitochondrial localization of thyroid hormone receptor (mTR) isoform in developing brain capable of binding a TH response element (DR2) present in D-loop region of mitochondrial DNA. These results thus indicate an integrated nuclear-mitochondrial cross talk in regulation of mitochondrial transcription by TH during brain development. Copyright 2010 Elsevier Inc. All rights reserved.

Evidence of a bigenomic regulation of mitochondrial gene expression by thyroid hormone during rat brain development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinha, Rohit Anthony; Pathak, Amrita; Mohan, Vishwa

Hypothyroidism during early mammalian brain development is associated with decreased expression of various mitochondrial encoded genes along with evidence for mitochondrial dysfunction. However, in-spite of the similarities between neurological disorders caused by perinatal hypothyroidism and those caused by various genetic mitochondrial defects we still do not know as to how thyroid hormone (TH) regulates mitochondrial transcription during development and whether this regulation by TH is nuclear mediated or through mitochondrial TH receptors? We here in rat cerebellum show that hypothyroidism causes reduction in expression of nuclear encoded genes controlling mitochondrial biogenesis like PGC-1{alpha}, NRF-1{alpha} and Tfam. Also, we for themore » first time demonstrate a mitochondrial localization of thyroid hormone receptor (mTR) isoform in developing brain capable of binding a TH response element (DR2) present in D-loop region of mitochondrial DNA. These results thus indicate an integrated nuclear-mitochondrial cross talk in regulation of mitochondrial transcription by TH during brain development.« less

Long-term preservation of retinal function in the RCS rat model of retinitis pigmentosa following lentivirus-mediated gene therapy.

PubMed

Tschernutter, M; Schlichtenbrede, F C; Howe, S; Balaggan, K S; Munro, P M; Bainbridge, J W B; Thrasher, A J; Smith, A J; Ali, R R

2005-04-01

The Royal College of Surgeons (RCS) rat is a well-characterized model of autosomal recessive retinitis pigmentosa (RP) due to a defect in the retinal pigment epithelium (RPE). It is homozygous for a null mutation in the gene encoding , a receptor tyrosine kinase found in RPE cells, that is required for phagocytosis of shed photoreceptor outer segments. The absence of Mertk results in accumulation of outer segment debris. This subsequently leads to progressive loss of photoreceptor cells. In order to evaluate the efficacy of lentiviral-mediated gene replacement therapy in the RCS rat, we produced recombinant VSV-G pseudotyped HIV-1-based lentiviruses containing a murine Mertk cDNA driven by a spleen focus forming virus (SFFV) promoter. The vector was subretinally injected into the right eye of 10-day-old RCS rats; the left eye was left untreated as an internal control. Here, we present a detailed assessment of the duration and extent of the morphological rescue and the resulting functional benefits. We examined animals at various time points over a period of 7 months by light and electron microscopy, and electroretinography. We observed correction of the phagocytic defect, slowing of photoreceptor cell loss and preservation of retinal function for up to 7 months. This study demonstrates the potential of gene therapy approaches for the treatment of retinal degenerations caused by defects specific to the RPE and supports the use of lentiviral vectors for the treatment of such disorders.

A human imprinting centre demonstrates conserved acquisition but diverged maintenance of imprinting in a mouse model for Angelman syndrome imprinting defects.

PubMed

Johnstone, Karen A; DuBose, Amanda J; Futtner, Christopher R; Elmore, Michael D; Brannan, Camilynn I; Resnick, James L

2006-02-01

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are caused by the loss of imprinted gene expression from chromosome 15q11-q13. Imprinted gene expression in the region is regulated by a bipartite imprinting centre (IC), comprising the PWS-IC and the AS-IC. The PWS-IC is a positive regulatory element required for bidirectional activation of a number of paternally expressed genes. The function of the AS-IC appears to be to suppress PWS-IC function on the maternal chromosome through a methylation imprint acquired during female gametogenesis. Here we have placed the entire mouse locus under the control of a human PWS-IC by targeted replacement of the mouse PWS-IC with the equivalent human region. Paternal inheritance of the human PWS-IC demonstrates for the first time that a positive regulatory element in the PWS-IC has diverged. These mice show postnatal lethality and growth deficiency, phenotypes not previously attributed directly to the affected genes. Following maternal inheritance, the human PWS-IC is able to acquire a methylation imprint in mouse oocytes, suggesting that acquisition of the methylation imprint is conserved. However, the imprint is lost in somatic cells, showing that maintenance has diverged. This maternal imprinting defect results in expression of maternal Ube3a-as and repression of Ube3a in cis, providing evidence that Ube3a is regulated by its antisense and creating the first reported mouse model for AS imprinting defects.

Overexpression of a truncated CTF7 construct leads to pleiotropic defects in reproduction and vegetative growth in Arabidopsis.

PubMed

Liu, Desheng; Makaroff, Christopher A

2015-03-05

Eco1/Ctf7 is essential for the establishment of sister chromatid cohesion during S phase of the cell cycle. Inactivation of Ctf7/Eco1 leads to a lethal phenotype in most organisms. Altering Eco1/Ctf7 levels or point mutations in the gene can lead to alterations in nuclear division as well as a wide range of developmental defects. Inactivation of Arabidopsis CTF7 (AtCTF7) results in severe defects in reproduction and vegetative growth. To further investigate the function(s) of AtCTF7, a tagged version of AtCTF7 and several AtCTF7 deletion constructs were created and transformed into wild type or ctf7 +/- plants. Transgenic plants expressing 35S:NTAP:AtCTF7∆299-345 (AtCTF7∆B) displayed a wide range of phenotypic alterations in reproduction and vegetative growth. Male meiocytes exhibited chromosome fragmentation and uneven chromosome segregation. Mutant ovules contained abnormal megasporocyte-like cells during pre-meiosis, megaspores experienced elongated meiosis and megagametogenesis, and defective megaspores/embryo sacs were produced at various stages. The transgenic plants also exhibited a broad range of vegetative defects, including meristem disruption and dwarfism that were inherited in a non-Mendelian fashion. Transcripts for epigenetically regulated transposable elements (TEs) were elevated in transgenic plants. Transgenic plants expressing 35S:AtCTF7∆B displayed similar vegetative defects, suggesting the defects in 35S:NTAP:AtCTF7∆B plants are caused by high-level expression of AtCTF7∆B. High level expression of AtCTF7∆B disrupts megasporogenesis, megagametogenesis and male meiosis, as well as causing a broad range of vegetative defects, including dwarfism that are inherited in a non-Mendelian fashion.

Beyond Epilepsy and Autism: Disruption of GABRB3 Causes Ocular Hypopigmentation.

PubMed

Delahanty, Ryan J; Zhang, Yanfeng; Bichell, Terry Jo; Shen, Wangzhen; Verdier, Kelienne; Macdonald, Robert L; Xu, Lili; Boyd, Kelli; Williams, Janice; Kang, Jing-Qiong

2016-12-20

Reduced ocular pigmentation is common in Angelman syndrome (AS) and Prader-Willi syndrome (PWS) and is long thought to be caused by OCA2 deletion. GABRB3 is located in the 15q11-13 region flanked by UBE3A, GABRA5, GABRG3, and OCA2. Mutations in GABRB3 have frequently been associated with epilepsy and autism, consistent with its role in neurodevelopment. We report here a robust phenotype in the mouse in which deletion of Gabrb3 alone causes nearly complete loss of retinal pigmentation due to atrophied melanosomes, as evidenced by electron microscopy. Using exome and RNA sequencing, we confirmed that only the Gabrb3 gene was disrupted while the Oca2 gene was intact. However, mRNA abundance of Oca2 and other genes adjacent to Gabrb3 is substantially reduced in Gabrb3 -/- mice, suggesting complex transcriptional regulation in this region. These results suggest that impairment in GABRB3 downregulates OCA2 and indirectly causes ocular hypopigmentation and visual defects in AS and PWS. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Genome-wide linkage analysis of congenital heart defects using MOD score analysis identifies two novel loci

PubMed Central

2013-01-01

Background Congenital heart defects (CHD) is the most common cause of death from a congenital structure abnormality in newborns and is often associated with fetal loss. There are many types of CHD. Human genetic studies have identified genes that are responsible for the inheritance of a particular type of CHD and for some types of CHD previously thought to be sporadic. However, occasionally different members of the same family might have anatomically distinct defects — for instance, one member with atrial septal defect, one with tetralogy of Fallot, and one with ventricular septal defect. Our objective is to identify susceptibility loci for CHD in families affected by distinct defects. The occurrence of these apparently discordant clinical phenotypes within one family might hint at a genetic framework common to most types of CHD. Results We performed a genome-wide linkage analysis using MOD score analysis in families with diverse CHD. Significant linkage was obtained in two regions, at chromosome 15 (15q26.3, Pempirical = 0.0004) and at chromosome 18 (18q21.2, Pempirical = 0.0005). Conclusions In these two novel regions four candidate genes are located: SELS, SNRPA1, and PCSK6 on 15q26.3, and TCF4 on 18q21.2. The new loci reported here have not previously been described in connection with CHD. Although further studies in other cohorts are needed to confirm these findings, the results presented here together with recent insight into how the heart normally develops will improve the understanding of CHD. PMID:23705960

CHARACTERIZING THE ROLE OF THE NELL1 GENE IN CARDIOVASCULAR DEVELOPMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, L. Y.; Culiat, C.

Nell1{sup 6R} is a chemically-induced point mutation in a novel cell-signaling gene, Nell1, which results in truncation of the protein and degradation of the Nell16R transcript. Earlier studies revealed that loss of Nell1 function reduces expression of numerous extracellular matrix (ECM) proteins required for differentiation of bone and cartilage precursor cells, thereby causing severe skull and spinal defects. Since skeletal and cardiovascular development are closely linked biological processes, this research focused on: a) examining Nell16R mutant mice for cardiovascular defects, b) determining Nell1 expression in fetal and adult hearts, and c) establishing how ECM genes affected by Nell1 infl uencemore » heart development. Structural heart defects in Nell16R mutant fetuses were analyzed by heart length and width measurements and standard histological methods (haematoxylin and eosin staining). Nell1 expression was assayed in fetal and adult hearts using reverse transcription polymerase chain reaction (RT-PCR). A comprehensive bioinformatics analysis using public databases (Stanford SOURCE Search, Integrated Cartilage Gene Database, Mouse Genome Informatics, and NCBI UniGene) was undertaken to investigate the relationship between cardiovascular development and each of twentyeight genes affected by Nell1. Nell1-defi cient mice have signifi cantly enlarged hearts (particularly the heart width), dramatically reduced blood fl ow out of the heart and unexpanded lungs. Isolation of total RNAs from hearts of adult (control and heterozygote) and fetal (control and homozygous mutant) mice have been completed and RT-PCR assays are in progress. The bioinformatics analysis showed that the majority of genes with reduced expression in Nell1-defi cient mice are normally expressed in the heart (79%; 22/28), blood vessels (71%; 20/28) and bone marrow (61%; 17/28). Moreover, mouse mutations in seven of these genes (Col15a1, Osf-2, Bmpr1a, Pkd1, Mfge8, Ptger4, Col5a1) manifest abnormalities in cardiovascular development. These data demonstrate for the fi rst time that Nell1 has a role in early mammalian cardiovascular development, mediated by its regulation of ECM proteins necessary for normal cell growth and differentiation. In addition, understanding the mechanisms by which Nell1 and its associated ECM genes affect the cardiovascular system can provide future strategies for the treatment of heart and blood vessel defects.« less

Mutations of the Imprinted CDKN1C Gene as a Cause of the Overgrowth Beckwith-Wiedemann Syndrome: Clinical Spectrum and Functional Characterization.

PubMed

Brioude, Frederic; Netchine, Irène; Praz, Francoise; Le Jule, Marilyne; Calmel, Claire; Lacombe, Didier; Edery, Patrick; Catala, Martin; Odent, Sylvie; Isidor, Bertrand; Lyonnet, Stanislas; Sigaudy, Sabine; Leheup, Bruno; Audebert-Bellanger, Séverine; Burglen, Lydie; Giuliano, Fabienne; Alessandri, Jean-Luc; Cormier-Daire, Valérie; Laffargue, Fanny; Blesson, Sophie; Coupier, Isabelle; Lespinasse, James; Blanchet, Patricia; Boute, Odile; Baumann, Clarisse; Polak, Michel; Doray, Berenice; Verloes, Alain; Viot, Géraldine; Le Bouc, Yves; Rossignol, Sylvie

2015-09-01

Beckwith-Wiedemann syndrome (BWS) is an imprinting disorder associating macroglossia, abdominal wall defects, visceromegaly, and a high risk of childhood tumor. Molecular anomalies are mostly epigenetic; however, mutations of CDKN1C are implicated in 8% of cases, including both sporadic and familial forms. We aimed to describe the phenotype of BWS patients with CDKN1C mutations and develop a functional test for CDKN1C mutations. For each propositus, we sequenced the three exons and intron-exon boundaries of CDKN1C in patients presenting a BWS phenotype, including abdominal wall defects, without 11p15 methylation defects. We developed a functional test based on flow cytometry. We identified 37 mutations in 38 pedigrees (50 patients and seven fetuses). Analysis of parental samples when available showed that all mutations tested but one was inherited from the mother. The four missense mutations led to a less severe phenotype (lower frequency of exomphalos) than the other 33 mutations. The following four tumors occurred: one neuroblastoma, one ganglioneuroblastoma, one melanoma, and one acute lymphoid leukemia. Cases of BWS caused by CDKN1C mutations are not rare. CDKN1C sequencing should be performed for BWS patients presenting with abdominal wall defects or cleft palate without 11p15 methylation defects or body asymmetry, or in familial cases of BWS. © 2015 WILEY PERIODICALS, INC.

GEMC1 is a critical regulator of multiciliated cell differentiation.

PubMed

Terré, Berta; Piergiovanni, Gabriele; Segura-Bayona, Sandra; Gil-Gómez, Gabriel; Youssef, Sameh A; Attolini, Camille Stephan-Otto; Wilsch-Bräuninger, Michaela; Jung, Carole; Rojas, Ana M; Marjanović, Marko; Knobel, Philip A; Palenzuela, Lluís; López-Rovira, Teresa; Forrow, Stephen; Huttner, Wieland B; Valverde, Miguel A; de Bruin, Alain; Costanzo, Vincenzo; Stracker, Travis H

2016-05-02

The generation of multiciliated cells (MCCs) is required for the proper function of many tissues, including the respiratory tract, brain, and germline. Defects in MCC development have been demonstrated to cause a subclass of mucociliary clearance disorders termed reduced generation of multiple motile cilia (RGMC). To date, only two genes, Multicilin (MCIDAS) and cyclin O (CCNO) have been identified in this disorder in humans. Here, we describe mice lacking GEMC1 (GMNC), a protein with a similar domain organization as Multicilin that has been implicated in DNA replication control. We have found that GEMC1-deficient mice are growth impaired, develop hydrocephaly with a high penetrance, and are infertile, due to defects in the formation of MCCs in the brain, respiratory tract, and germline. Our data demonstrate that GEMC1 is a critical regulator of MCC differentiation and a candidate gene for human RGMC or related disorders. © 2016 The Authors.

A 20-basepair duplication in the human thyroid peroxidase gene results in a total iodide organification defect and congenital hypothyroidism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bikker, H.; Hartog, M.T. den; Gons, M.H.

1994-07-01

In this study, the authors present the molecular basis of a total iodide organification defect causing severe congenital hypothyroidism. In the thyroid gland of the patient, thyroid peroxidase (TPO) activity and the iodination degree of thyroglobulin were below detection limits, and no TPO messenger ribonucleic acid was detectable by Northern blot analysis. Denaturing gradient gel electrophoretic analysis of the TPO gene of the patient revealed a homozygous mutation in exon 2. Sequence analysis showed the presence of a 20-basepair duplication, 47 basepairs down-stream of the ATG start codon. This duplication generates a frame shift, resulting in a termination signal inmore » exon 3, compatible with the complete absence of TPO. Both parents of the patient are heterozygous for the same duplication, confirming the recessive mode of inheritance of the mutation. 32 refs., 4 figs.« less

Unique presentation of cutis laxa with Leigh-like syndrome due to ECHS1 deficiency.

PubMed

Balasubramaniam, S; Riley, L G; Bratkovic, D; Ketteridge, D; Manton, N; Cowley, M J; Gayevskiy, V; Roscioli, T; Mohamed, M; Gardeitchik, T; Morava, E; Christodoulou, J

2017-09-01

Clinical finding of cutis laxa, characterized by wrinkled, redundant, sagging, nonelastic skin, is of growing significance due to its occurrence in several different inborn errors of metabolism (IEM). Metabolic cutis laxa results from Menkes syndrome, caused by a defect in the ATPase copper transporting alpha (ATP7A) gene; congenital disorders of glycosylation due to mutations in subunit 7 of the component of oligomeric Golgi (COG7)-congenital disorders of glycosylation (CDG) complex; combined disorder of N- and O-linked glycosylation, due to mutations in ATPase H+ transporting V0 subunit a2 (ATP6VOA2) gene; pyrroline-5-carboxylate reductase 1 deficiency; pyrroline-5-carboxylate synthase deficiency; macrocephaly, alopecia, cutis laxa, and scoliosis (MACS) syndrome, due to Ras and Rab interactor 2 (RIN2) mutations; transaldolase deficiency caused by mutations in the transaldolase 1 (TALDO1) gene; Gerodermia osteodysplastica due to mutations in the golgin, RAB6-interacting (GORAB or SCYL1BP1) gene; and mitogen-activated pathway (MAP) kinase defects, caused by mutations in several genes [protein tyrosine phosphatase, non-receptor-type 11 (PTPN11), RAF, NF, HRas proto-oncogene, GTPase (HRAS), B-Raf proto-oncogene, serine/threonine kinase (BRAF), MEK1/2, KRAS proto-oncogene, GTPase (KRAS), SOS Ras/Rho guanine nucleotide exchange factor 2 (SOS2), leucine rich repeat scaffold protein (SHOC2), NRAS proto-oncogene, GTPase (NRAS), and Raf-1 proto-oncogene, serine/threonine kinase (RAF1)], which regulate the Ras-MAPK cascade. Here, we further expand the list of inborn errors of metabolism associated with cutis laxa by describing the clinical presentation of a 17-month-old girl with Leigh-like syndrome due to enoyl coenzyme A hydratase, short chain, 1, mitochondria (ECHS1) deficiency, a mitochondrial matrix enzyme that catalyzes the second step of the beta-oxidation spiral of fatty acids and plays an important role in amino acid catabolism, particularly valine.

The 8-oxoguanine DNA glycosylase 1 (ogg1) decreases the vulnerability of the developing brain to DNA damage.

PubMed

Gu, Aihua; Ji, Guixiang; Yan, Lifeng; Zhou, Yong

2013-12-01

The developing brain is particularly vulnerable to oxidative DNA damage, which may be the cause of most major congenital mental anomalies. The repair enzyme ogg1 initiates the highly conserved base-excision repair pathway. However, its function in the embryonic brain is largely unknown. This study is the first to validate the function of ogg1 during brain development using zebrafish embryos. Ogg1 was found to be highly expressed in the brain throughout early embryonic development, with particularly enrichment observed in the midbrain. The lack of ogg1 causes severe brain defects including changes in brain volume and integrity, destruction of the midbrain-hindbrain boundary, and balance and motor impairment, while overexpression of ogg1 can partially rescue these defects. Multiple cellular and molecular events were involved in the manifestation of brain defects due primarily to the lack of ogg1. These included (1) increased apoptosis; (2) decreased proliferation; and (3) aberrant axon distribution and extension from the inner surface towards the outer layers. The results of a microarray analysis showed that the expression of genes involved in cell cycle checkpoint, apoptosis, and neurogenesis were significantly changed in response to ogg1 knockdown. Cmyb was the key downstream gene that responses to DNA damage caused by ogg1 deficiency. Notably, the recruitment of ogg1 mRNA can alleviate the effects on the brain due to neural DNA damage. In summary, we introduce here that ogg1 is fundamentally required for protecting the developing brain, which may be helpful in understanding the aetiology of congenital brain deficits. Copyright © 2013 Elsevier B.V. All rights reserved.

Hypomorphic Recessive Variants in SUFU Impair the Sonic Hedgehog Pathway and Cause Joubert Syndrome with Cranio-facial and Skeletal Defects.

PubMed

De Mori, Roberta; Romani, Marta; D'Arrigo, Stefano; Zaki, Maha S; Lorefice, Elisa; Tardivo, Silvia; Biagini, Tommaso; Stanley, Valentina; Musaev, Damir; Fluss, Joel; Micalizzi, Alessia; Nuovo, Sara; Illi, Barbara; Chiapparini, Luisa; Di Marcotullio, Lucia; Issa, Mahmoud Y; Anello, Danila; Casella, Antonella; Ginevrino, Monia; Leggins, Autumn Sa'na; Roosing, Susanne; Alfonsi, Romina; Rosati, Jessica; Schot, Rachel; Mancini, Grazia Maria Simonetta; Bertini, Enrico; Dobyns, William B; Mazza, Tommaso; Gleeson, Joseph G; Valente, Enza Maria

2017-10-05

The Sonic Hedgehog (SHH) pathway is a key signaling pathway orchestrating embryonic development, mainly of the CNS and limbs. In vertebrates, SHH signaling is mediated by the primary cilium, and genetic defects affecting either SHH pathway members or ciliary proteins cause a spectrum of developmental disorders. SUFU is the main negative regulator of the SHH pathway and is essential during development. Indeed, Sufu knock-out is lethal in mice, and recessive pathogenic variants of this gene have never been reported in humans. Through whole-exome sequencing in subjects with Joubert syndrome, we identified four children from two unrelated families carrying homozygous missense variants in SUFU. The children presented congenital ataxia and cerebellar vermis hypoplasia with elongated superior cerebellar peduncles (mild "molar tooth sign"), typical cranio-facial dysmorphisms (hypertelorism, depressed nasal bridge, frontal bossing), and postaxial polydactyly. Two siblings also showed polymicrogyria. Molecular dynamics simulation predicted random movements of the mutated residues, with loss of the native enveloping movement of the binding site around its ligand GLI3. Functional studies on cellular models and fibroblasts showed that both variants significantly reduced SUFU stability and its capacity to bind GLI3 and promote its cleavage into the repressor form GLI3R. In turn, this impaired SUFU-mediated repression of the SHH pathway, as shown by altered expression levels of several target genes. We demonstrate that germline hypomorphic variants of SUFU cause deregulation of SHH signaling, resulting in recessive developmental defects of the CNS and limbs which share features with both SHH-related disorders and ciliopathies. Copyright © 2017 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

NAD Deficiency, Congenital Malformations, and Niacin Supplementation.

PubMed

Shi, Hongjun; Enriquez, Annabelle; Rapadas, Melissa; Martin, Ella M M A; Wang, Roni; Moreau, Julie; Lim, Chai K; Szot, Justin O; Ip, Eddie; Hughes, James N; Sugimoto, Kotaro; Humphreys, David T; McInerney-Leo, Aideen M; Leo, Paul J; Maghzal, Ghassan J; Halliday, Jake; Smith, Janine; Colley, Alison; Mark, Paul R; Collins, Felicity; Sillence, David O; Winlaw, David S; Ho, Joshua W K; Guillemin, Gilles J; Brown, Matthew A; Kikuchi, Kazu; Thomas, Paul Q; Stocker, Roland; Giannoulatou, Eleni; Chapman, Gavin; Duncan, Emma L; Sparrow, Duncan B; Dunwoodie, Sally L

2017-08-10

Congenital malformations can be manifested as combinations of phenotypes that co-occur more often than expected by chance. In many such cases, it has proved difficult to identify a genetic cause. We sought the genetic cause of cardiac, vertebral, and renal defects, among others, in unrelated patients. We used genomic sequencing to identify potentially pathogenic gene variants in families in which a person had multiple congenital malformations. We tested the function of the variant by using assays of in vitro enzyme activity and by quantifying metabolites in patient plasma. We engineered mouse models with similar variants using the CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 system. Variants were identified in two genes that encode enzymes of the kynurenine pathway, 3-hydroxyanthranilic acid 3,4-dioxygenase (HAAO) and kynureninase (KYNU). Three patients carried homozygous variants predicting loss-of-function changes in the HAAO or KYNU proteins (HAAO p.D162*, HAAO p.W186*, or KYNU p.V57Efs*21). Another patient carried heterozygous KYNU variants (p.Y156* and p.F349Kfs*4). The mutant enzymes had greatly reduced activity in vitro. Nicotinamide adenine dinucleotide (NAD) is synthesized de novo from tryptophan through the kynurenine pathway. The patients had reduced levels of circulating NAD. Defects similar to those in the patients developed in the embryos of Haao-null or Kynu-null mice owing to NAD deficiency. In null mice, the prevention of NAD deficiency during gestation averted defects. Disruption of NAD synthesis caused a deficiency of NAD and congenital malformations in humans and mice. Niacin supplementation during gestation prevented the malformations in mice. (Funded by the National Health and Medical Research Council of Australia and others.).

An XRCC4 Splice Mutation Associated With Severe Short Stature, Gonadal Failure, and Early-Onset Metabolic Syndrome

PubMed Central

de Bruin, Christiaan; Mericq, Verónica; Andrew, Shayne F.; van Duyvenvoorde, Hermine A.; Verkaik, Nicole S.; Losekoot, Monique; Porollo, Aleksey; Garcia, Hernán; Kuang, Yi; Hanson, Dan; Clayton, Peter; van Gent, Dik C.; Wit, Jan M.; Hwa, Vivian

2015-01-01

Context: Severe short stature can be caused by defects in numerous biological processes including defects in IGF-1 signaling, centromere function, cell cycle control, and DNA damage repair. Many syndromic causes of short stature are associated with medical comorbidities including hypogonadism and microcephaly. Objective: To identify an underlying genetic etiology in two siblings with severe short stature and gonadal failure. Design: Clinical phenotyping, genetic analysis, complemented by in vitro functional studies of the candidate gene. Setting: An academic pediatric endocrinology clinic. Patients or Other Participants: Two adult siblings (male patient [P1] and female patient 2 [P2]) presented with a history of severe postnatal growth failure (adult heights: P1, −6.8 SD score; P2, −4 SD score), microcephaly, primary gonadal failure, and early-onset metabolic syndrome in late adolescence. In addition, P2 developed a malignant gastrointestinal stromal tumor at age 28. Intervention(s): Single nucleotide polymorphism microarray and exome sequencing. Results: Combined microarray analysis and whole exome sequencing of the two affected siblings and one unaffected sister identified a homozygous variant in XRCC4 as the probable candidate variant. Sanger sequencing and mRNA studies revealed a splice variant resulting in an in-frame deletion of 23 amino acids. Primary fibroblasts (P1) showed a DNA damage repair defect. Conclusions: In this study we have identified a novel pathogenic variant in XRCC4, a gene that plays a critical role in non-homologous end-joining DNA repair. This finding expands the spectrum of DNA damage repair syndromes to include XRCC4 deficiency causing severe postnatal growth failure, microcephaly, gonadal failure, metabolic syndrome, and possibly tumor predisposition. PMID:25742519

Characterizing and Targeting Replication Stress Response Defects in Breast Cancer

DTIC Science & Technology

2013-08-01

This project is to use cutting-edge technologies to characterize novel RSR genes and their functions in tumor suppression; identify gene signature...and membrane proteins associated with defective RSR; identify drugs that target these defects; and develop RSR-defect-targeting nanoparticles for...screening and validation of drugs that target RSR-defect cells. The progress of our third year research is described below. BODY The tasks

Establishment of a Mouse Model with Misregulated Chromosome Condensation due to Defective Mcph1 Function

PubMed Central

Walther, Diego J.; Dopatka, Monika; Dutrannoy, Véronique; Busche, Andreas; Meyer, Franziska; Nowak, Stefanie; Nowak, Jean; Zabel, Claus; Klose, Joachim; Esquitino, Veronica; Garshasbi, Masoud; Kuss, Andreas W.; Ropers, Hans-Hilger; Mueller, Susanne; Poehlmann, Charlotte; Gavvovidis, Ioannis; Schindler, Detlev; Sperling, Karl; Neitzel, Heidemarie

2010-01-01

Mutations in the human gene MCPH1 cause primary microcephaly associated with a unique cellular phenotype with premature chromosome condensation (PCC) in early G2 phase and delayed decondensation post-mitosis (PCC syndrome). The gene encodes the BRCT-domain containing protein microcephalin/BRIT1. Apart from its role in the regulation of chromosome condensation, the protein is involved in the cellular response to DNA damage. We report here on the first mouse model of impaired Mcph1-function. The model was established based on an embryonic stem cell line from BayGenomics (RR0608) containing a gene trap in intron 12 of the Mcph1 gene deleting the C-terminal BRCT-domain of the protein. Although residual wild type allele can be detected by quantitative real-time PCR cell cultures generated from mouse tissues bearing the homozygous gene trap mutation display the cellular phenotype of misregulated chromosome condensation that is characteristic for the human disorder, confirming defective Mcph1 function due to the gene trap mutation. While surprisingly the DNA damage response (formation of repair foci, chromosomal breakage, and G2/M checkpoint function after irradiation) appears to be largely normal in cell cultures derived from Mcph1gt/gt mice, the overall survival rates of the Mcph1gt/gt animals are significantly reduced compared to wild type and heterozygous mice. However, we could not detect clear signs of premature malignant disease development due to the perturbed Mcph1 function. Moreover, the animals show no obvious physical phenotype and no reduced fertility. Body and brain size are within the range of wild type controls. Gene expression on RNA and protein level did not reveal any specific pattern of differentially regulated genes. To the best of our knowledge this represents the first mammalian transgenic model displaying a defect in mitotic chromosome condensation and is also the first mouse model for impaired Mcph1-function. PMID:20169082

Establishment of a mouse model with misregulated chromosome condensation due to defective Mcph1 function.

PubMed

Trimborn, Marc; Ghani, Mahdi; Walther, Diego J; Dopatka, Monika; Dutrannoy, Véronique; Busche, Andreas; Meyer, Franziska; Nowak, Stefanie; Nowak, Jean; Zabel, Claus; Klose, Joachim; Esquitino, Veronica; Garshasbi, Masoud; Kuss, Andreas W; Ropers, Hans-Hilger; Mueller, Susanne; Poehlmann, Charlotte; Gavvovidis, Ioannis; Schindler, Detlev; Sperling, Karl; Neitzel, Heidemarie

2010-02-16

Mutations in the human gene MCPH1 cause primary microcephaly associated with a unique cellular phenotype with premature chromosome condensation (PCC) in early G2 phase and delayed decondensation post-mitosis (PCC syndrome). The gene encodes the BRCT-domain containing protein microcephalin/BRIT1. Apart from its role in the regulation of chromosome condensation, the protein is involved in the cellular response to DNA damage. We report here on the first mouse model of impaired Mcph1-function. The model was established based on an embryonic stem cell line from BayGenomics (RR0608) containing a gene trap in intron 12 of the Mcph1 gene deleting the C-terminal BRCT-domain of the protein. Although residual wild type allele can be detected by quantitative real-time PCR cell cultures generated from mouse tissues bearing the homozygous gene trap mutation display the cellular phenotype of misregulated chromosome condensation that is characteristic for the human disorder, confirming defective Mcph1 function due to the gene trap mutation. While surprisingly the DNA damage response (formation of repair foci, chromosomal breakage, and G2/M checkpoint function after irradiation) appears to be largely normal in cell cultures derived from Mcph1(gt/gt) mice, the overall survival rates of the Mcph1(gt/gt) animals are significantly reduced compared to wild type and heterozygous mice. However, we could not detect clear signs of premature malignant disease development due to the perturbed Mcph1 function. Moreover, the animals show no obvious physical phenotype and no reduced fertility. Body and brain size are within the range of wild type controls. Gene expression on RNA and protein level did not reveal any specific pattern of differentially regulated genes. To the best of our knowledge this represents the first mammalian transgenic model displaying a defect in mitotic chromosome condensation and is also the first mouse model for impaired Mcph1-function.

Defects in the Fanconi Anemia Pathway and Chromatid Cohesion in Head and Neck Cancer.

PubMed

Stoepker, Chantal; Ameziane, Najim; van der Lelij, Petra; Kooi, Irsan E; Oostra, Anneke B; Rooimans, Martin A; van Mil, Saskia E; Brink, Arjen; Dietrich, Ralf; Balk, Jesper A; Ylstra, Bauke; Joenje, Hans; Feller, Stephan M; Brakenhoff, Ruud H

2015-09-01

Failure to repair DNA damage or defective sister chromatid cohesion, a process essential for correct chromosome segregation, can be causative of chromosomal instability (CIN), which is a hallmark of many types of cancers. We investigated how frequent this occurs in head and neck squamous cell carcinoma (HNSCC) and whether specific mechanisms or genes could be linked to these phenotypes. The genomic instability syndrome Fanconi anemia is caused by mutations in any of at least 16 genes regulating DNA interstrand crosslink (ICL) repair. Since patients with Fanconi anemia have a high risk to develop HNSCC, we investigated whether and to which extent Fanconi anemia pathway inactivation underlies CIN in HNSCC of non-Fanconi anemia individuals. We observed ICL-induced chromosomal breakage in 9 of 17 (53%) HNSCC cell lines derived from patients without Fanconi anemia. In addition, defective sister chromatid cohesion was observed in five HNSCC cell lines. Inactivation of FANCM was responsible for chromosomal breakage in one cell line, whereas in two other cell lines, somatic mutations in PDS5A or STAG2 resulted in inadequate sister chromatid cohesion. In addition, FANCF methylation was found in one cell line by screening an additional panel of 39 HNSCC cell lines. Our data demonstrate that CIN in terms of ICL-induced chromosomal breakage and defective chromatid cohesion is frequently observed in HNSCC. Inactivation of known Fanconi anemia and chromatid cohesion genes does explain CIN in the minority of cases. These findings point to phenotypes that may be highly relevant in treatment response of HNSCC. ©2015 American Association for Cancer Research.

Early transcriptional responses of internalization defective Brucella abortus mutants in professional phagocytes, RAW 264.7.

PubMed

Cha, Seung Bin; Lee, Won Jung; Shin, Min Kyoung; Jung, Myung Hwan; Shin, Seung Won; Yoo, An Na; Kim, Jong Wan; Yoo, Han Sang

2013-06-27

Brucella abortus is an intracellular zoonotic pathogen which causes undulant fever, endocarditis, arthritis and osteomyelitis in human and abortion and infertility in cattle. This bacterium is able to invade and replicate in host macrophage instead of getting removed by this defense mechanism. Therefore, understanding the interaction between virulence of the bacteria and the host cell is important to control brucellosis. Previously, we generated internalization defective mutants and analyzed the envelope proteins. The present study was undertaken to evaluate the changes in early transcriptional responses between wild type and internalization defective mutants infected mouse macrophage, RAW 264.7. Both of the wild type and mutant infected macrophages showed increased expression levels in proinflammatory cytokines, chemokines, apoptosis and G-protein coupled receptors (Gpr84, Gpr109a and Adora2b) while the genes related with small GTPase which mediate intracellular trafficking was decreased. Moreover, cytohesin 1 interacting protein (Cytip) and genes related to ubiquitination (Arrdc3 and Fbxo21) were down-regulated, suggesting the survival strategy of this bacterium. However, we could not detect any significant changes in the mutant infected groups compared to the wild type infected group. In summary, it was very difficult to clarify the alterations in host cellular transcription in response to infection with internalization defective mutants. However, we found several novel gene changes related to the GPCR system, ubiquitin-proteosome system, and growth arrest and DNA damages in response to B. abortus infection. These findings may contribute to a better understanding of the molecular mechanisms underlying host-pathogen interactions and need to be studied further.

Early transcriptional responses of internalization defective Brucella abortus mutants in professional phagocytes, RAW 264.7

PubMed Central

2013-01-01

Background Brucella abortus is an intracellular zoonotic pathogen which causes undulant fever, endocarditis, arthritis and osteomyelitis in human and abortion and infertility in cattle. This bacterium is able to invade and replicate in host macrophage instead of getting removed by this defense mechanism. Therefore, understanding the interaction between virulence of the bacteria and the host cell is important to control brucellosis. Previously, we generated internalization defective mutants and analyzed the envelope proteins. The present study was undertaken to evaluate the changes in early transcriptional responses between wild type and internalization defective mutants infected mouse macrophage, RAW 264.7. Results Both of the wild type and mutant infected macrophages showed increased expression levels in proinflammatory cytokines, chemokines, apoptosis and G-protein coupled receptors (Gpr84, Gpr109a and Adora2b) while the genes related with small GTPase which mediate intracellular trafficking was decreased. Moreover, cytohesin 1 interacting protein (Cytip) and genes related to ubiquitination (Arrdc3 and Fbxo21) were down-regulated, suggesting the survival strategy of this bacterium. However, we could not detect any significant changes in the mutant infected groups compared to the wild type infected group. Conclusions In summary, it was very difficult to clarify the alterations in host cellular transcription in response to infection with internalization defective mutants. However, we found several novel gene changes related to the GPCR system, ubiquitin-proteosome system, and growth arrest and DNA damages in response to B. abortus infection. These findings may contribute to a better understanding of the molecular mechanisms underlying host-pathogen interactions and need to be studied further. PMID:23802650

Mutation of SALL2 causes recessive ocular coloboma in humans and mice

PubMed Central

Kelberman, Daniel; Islam, Lily; Lakowski, Jörn; Bacchelli, Chiara; Chanudet, Estelle; Lescai, Francesco; Patel, Aara; Stupka, Elia; Buck, Anja; Wolf, Stephan; Beales, Philip L.; Jacques, Thomas S.; Bitner-Glindzicz, Maria; Liasis, Alki; Lehmann, Ordan J.; Kohlhase, Jürgen; Nischal, Ken K.; Sowden, Jane C.

2014-01-01

Ocular coloboma is a congenital defect resulting from failure of normal closure of the optic fissure during embryonic eye development. This birth defect causes childhood blindness worldwide, yet the genetic etiology is poorly understood. Here, we identified a novel homozygous mutation in the SALL2 gene in members of a consanguineous family affected with non-syndromic ocular coloboma variably affecting the iris and retina. This mutation, c.85G>T, introduces a premature termination codon (p.Glu29*) predicted to truncate the SALL2 protein so that it lacks three clusters of zinc-finger motifs that are essential for DNA-binding activity. This discovery identifies SALL2 as the third member of the Drosophila homeotic Spalt-like family of developmental transcription factor genes implicated in human disease. SALL2 is expressed in the developing human retina at the time of, and subsequent to, optic fissure closure. Analysis of Sall2-deficient mouse embryos revealed delayed apposition of the optic fissure margins and the persistence of an anterior retinal coloboma phenotype after birth. Sall2-deficient embryos displayed correct posterior closure toward the optic nerve head, and upon contact of the fissure margins, dissolution of the basal lamina occurred and PAX2, known to be critical for this process, was expressed normally. Anterior closure was disrupted with the fissure margins failing to meet, or in some cases misaligning leading to a retinal lesion. These observations demonstrate, for the first time, a role for SALL2 in eye morphogenesis and that loss of function of the gene causes ocular coloboma in humans and mice. PMID:24412933

Mutations in the G6PC3 gene cause Dursun syndrome.

PubMed

Banka, Siddharth; Newman, William G; Ozgül, R Koksal; Dursun, Ali

2010-10-01

Dursun syndrome is a triad of familial primary pulmonary hypertension, leucopenia, and atrial septal defect. Here we demonstrate that mutations in G6PC3 cause Dursun syndrome. Mutations in G6PC3 are known to also cause severe congenital neutropenia type 4. Identification of the genetic basis of Dursun syndrome expands the pre-existing knowledge about the phenotypic effects of mutations in G6PC3. We propose that Dursun syndrome should now be considered as a subset of severe congenital neutropenia type 4 with pulmonary hypertension as an important clinical feature. Copyright © 2010 Wiley-Liss, Inc.

Current concepts in periodontal bioengineering

PubMed Central

Taba, M.; Jin, Q.; Sugai, J.V.; Giannobile, W.V.

2008-01-01

Repair of tooth supporting alveolar bone defects caused by periodontal and peri-implant tissue destruction is a major goal of reconstructive therapy. Oral and craniofacial tissue engineering has been achieved with limited success by the utilization of a variety of approaches such as cell-occlusive barrier membranes, bone substitutes and autogenous block grafting techniques. Signaling molecules such as growth factors have been used to restore lost tooth support because of damage by periodontal disease or trauma. This paper will review emerging periodontal therapies in the areas of materials science, growth factor biology and cell/gene therapy. Several different polymer delivery systems that aid in the targeting of proteins, genes and cells to periodontal and peri-implant defects will be highlighted. Results from preclinical and clinical trials will be reviewed using the topical application of bone morphogenetic proteins (BMP-2 and BMP-7) and platelet-derived growth factor-BB (PDGF) for periodontal and peri-implant regeneration. The paper concludes with recent research on the use of ex vivo and in vivo gene delivery strategies via gene therapy vectors encoding growth promoting and inhibiting molecules (PDGF, BMP, noggin and others) to regenerate periodontal structures including bone, periodontal ligament and cementum. PMID:16238610

A novel Xp22.13 microdeletion in Nance-Horan syndrome.

PubMed

Accogli, Andrea; Traverso, Monica; Madia, Francesca; Bellini, Tommaso; Vari, Maria Stella; Pinto, Francesca; Capra, Valeria

2017-07-03

Nance-Horan syndrome (NHS) is a rare X-linked developmental disorder characterized by congenital cataract, dental anomalies and facial dysmorphisms. Notably, up to 30% of NHS patients have intellectual disability and a few patients have been reported to have congenital cardiac defects. Nance-Horan syndrome is caused by mutations in the NHS gene that is highly expressed in the midbrain, retina, lens, tooth, and is conserved across vertebrate species. Although most pathogenic mutations are nonsense mutations, a few genomic rearrangements involving NHS locus have been reported, suggesting a possible pathogenic role of the flanking genes. Here, we report a microdeletion of 170,6 Kb at Xp22.13 (17.733.948-17.904.576) (GRCh37/hg19), detected by array-based comparative genomic hybridization in an Italian boy with NHS syndrome. The microdeletion harbors the NHS, SCLML1, and RAI2 genes and results in a phenotype consistent with NSH syndrome and developmental delay. We compare our case with the previous Xp22.13 microdeletions and discuss the possible pathogenetic role of the flanking genes. Birth Defects Research 109:866-868, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Haploinsufficiency for Adrenomedullin Reduces Pinopodes and Diminishes Uterine Receptivity in Mice1

PubMed Central

Li, Manyu; Wu, Yongqin; Caron, Kathleen M.

2008-01-01

Adrenomedullin (AM) is a multifunctional peptide vasodilator that signals through a G-protein-coupled receptor when the receptor, called calcitonin receptor-like receptor (CL), is associated with a receptor activity-modifying protein 2 (RAMP2). We demonstrated previously that haploinsufficieny for each of these genes led to reduced maternal fertility, and that even a modest genetic reduction of AM peptide caused maternal defects in implantation, placentation, and fetal growth. Here, we further demonstrate that Adm+/− female mice displayed reduced pregnancy success rates that were not caused by defects in folliculogenesis, ovulation, or fertilization. The poor fertility of Adm+/− female mice could not be rescued by transfer of wild-type blastocysts, which suggested an underlying defect in uterine receptivity. In fact, we found that Adm, Calcrl, and Ramp2 gene expressions are tightly and spatiotemporally regulated in the luminal epithelial cells of the uterus during the estrus cycle and the peri-implantation period. RAMP3, which also generates an AM receptor when associated with CL, had a diametrically opposite expression pattern than that of Adm, Calcrl, and Ramp2 and was most robustly induced in the stroma of the uterus. Finally, we discovered that Adm+/− female mice have a substantially reduced number of pinopodes on the uterine luminal epithelial surface, which is indicative and possibly causative of the poor uterine receptivity. Taken together, our studies identify a new class of pharmacologically tractable proteins that are involved in establishing uterine receptivity through the regulation of pinopode formation. PMID:18716289

Impaired fast-spiking interneuron function in a genetic mouse model of depression

PubMed Central

Sauer, Jonas-Frederic; Strüber, Michael; Bartos, Marlene

2015-01-01

Rhythmic neuronal activity provides a frame for information coding by co-active cell assemblies. Abnormal brain rhythms are considered as potential pathophysiological mechanisms causing mental disease, but the underlying network defects are largely unknown. We find that mice expressing truncated Disrupted-in-Schizophrenia 1 (Disc1), which mirror a high-prevalence genotype for human psychiatric illness, show depression-related behavior. Theta and low-gamma synchrony in the prelimbic cortex (PrlC) is impaired in Disc1 mice and inversely correlated with the extent of behavioural despair. While weak theta activity is driven by the hippocampus, disturbance of low-gamma oscillations is caused by local defects of parvalbumin (PV)-expressing fast-spiking interneurons (FS-INs). The number of FS-INs is reduced, they receive fewer excitatory inputs, and form fewer release sites on targets. Computational analysis indicates that weak excitatory input and inhibitory output of FS-INs may lead to impaired gamma oscillations. Our data link network defects with a gene mutation underlying depression in humans. DOI: http://dx.doi.org/10.7554/eLife.04979.001 PMID:25735038

Post-natal myogenic and adipogenic developmental

PubMed Central

Konings, Gonda; van Weeghel, Michel; van den Hoogenhof, Maarten MG; Gijbels, Marion; van Erk, Arie; Schoonderwoerd, Kees; van den Bosch, Bianca; Dahlmans, Vivian; Calis, Chantal; Houten, Sander M; Misteli, Tom

2011-01-01

A-type lamins are a major component of the nuclear lamina. Mutations in the LMNA gene, which encodes the A-type lamins A and C, cause a set of phenotypically diverse diseases collectively called laminopathies. While adult LMNA null mice show various symptoms typically associated with laminopathies, the effect of loss of lamin A/C on early post-natal development is poorly understood. Here we developed a novel LMNA null mouse (LMNAGT−/−) based on genetrap technology and analyzed its early post-natal development. We detect LMNA transcripts in heart, the outflow tract, dorsal aorta, liver and somites during early embryonic development. Loss of A-type lamins results in severe growth retardation and developmental defects of the heart, including impaired myocyte hypertrophy, skeletal muscle hypotrophy, decreased amounts of subcutaneous adipose tissue and impaired ex vivo adipogenic differentiation. These defects cause death at 2 to 3 weeks post partum associated with muscle weakness and metabolic complications, but without the occurrence of dilated cardiomyopathy or an obvious progeroid phenotype. Our results indicate that defective early post-natal development critically contributes to the disease phenotypes in adult laminopathies. PMID:21818413

A novel mutation in SLITRK6 causes deafness and myopia in a Moroccan family.

PubMed

Salime, Sara; Riahi, Zied; Elrharchi, Soukaina; Elkhattabi, Lamiae; Charoute, Hicham; Nahili, Halima; Rouba, Hassan; Kabine, Mostafa; Bonnet, Crystel; Petit, Christine; Barakat, Abdelhamid

2018-06-15

Deafness and myopia syndrome is characterized by moderate-profound, bilateral, congenital or prelingual deafness and high myopia. Autosomal recessive non-syndromic hearing loss is one of the most prevalent human genetic sensorineural defects. Myopia is by far the most common human eye disorder that is known to have a clear heritable component. The analysis of the two exons of SLITRK6 gene in a Moroccan family allowed us to identify a novel single deleterious mutation c.696delG, p.Trp232Cysfs*10 at homozygous state in the exon 2 of the SLITRK6, a gene reported to cause deafness and myopia in various populations. Copyright © 2018 Elsevier B.V. All rights reserved.

PROKR2 and PROK2 mutations cause isolated congenital anosmia without gonadotropic deficiency.

PubMed

Moya-Plana, Antoine; Villanueva, Carine; Laccourreye, Ollivier; Bonfils, Pierre; de Roux, Nicolas

2013-01-01

Isolated congenital anosmia (ICA) is a rare phenotype defined as absent recall of any olfactory sensations since birth and the absence of any disease known to cause anosmia. Although most cases of ICA are sporadic, reports of familial cases suggest a genetic cause. ICA due to olfactory bulb agenesis and associated to hypogonadotropic hypogonadism defines Kallmann syndrome (KS), in which several gene defects have been described. In KS families, the phenotype may be restricted to ICA. We therefore hypothesized that mutations in KS genes cause ICA in patients, even in the absence of family history of reproduction disorders. In 25 patients with ICA and olfactory bulb agenesis, a detailed phenotype analysis was conducted and the coding sequences of KAL1, FGFR1, FGF8, PROKR2, and PROK2 were sequenced. Three PROKR2 mutations previously described in KS and one new PROK2 mutation were found. Investigation of the families showed incomplete penetrance of these mutations. This study is the first to report genetic causes of ICA and indicates that KS genes must be screened in patients with ICA. It also confirms the considerable complexity of GNRH neuron development in humans.

Genes Contributing to Porphyromonas gingivalis Fitness in Abscess and Epithelial Cell Colonization Environments

PubMed Central

Miller, Daniel P.; Hutcherson, Justin A.; Wang, Yan; Nowakowska, Zuzanna M.; Potempa, Jan; Yoder-Himes, Deborah R.; Scott, David A.; Whiteley, Marvin; Lamont, Richard J.

2017-01-01

Porphyromonas gingivalis is an important cause of serious periodontal diseases, and is emerging as a pathogen in several systemic conditions including some forms of cancer. Initial colonization by P. gingivalis involves interaction with gingival epithelial cells, and the organism can also access host tissues and spread haematogenously. To better understand the mechanisms underlying these properties, we utilized a highly saturated transposon insertion library of P. gingivalis, and assessed the fitness of mutants during epithelial cell colonization and survival in a murine abscess model by high-throughput sequencing (Tn-Seq). Transposon insertions in many genes previously suspected as contributing to virulence showed significant fitness defects in both screening assays. In addition, a number of genes not previously associated with P. gingivalis virulence were identified as important for fitness. We further examined fitness defects of four such genes by generating defined mutations. Genes encoding a carbamoyl phosphate synthetase, a replication-associated recombination protein, a nitrosative stress responsive HcpR transcription regulator, and RNase Z, a zinc phosphodiesterase, showed a fitness phenotype in epithelial cell colonization and in a competitive abscess infection. This study verifies the importance of several well-characterized putative virulence factors of P. gingivalis and identifies novel fitness determinants of the organism. PMID:28900609

Autoimmunity and primary immunodeficiency: two sides of the same coin?

PubMed

Schmidt, Reinhold E; Grimbacher, Bodo; Witte, Torsten

2017-12-19

Autoimmunity and immunodeficiency were previously considered to be mutually exclusive conditions; however, increased understanding of the complex immune regulatory and signalling mechanisms involved, coupled with the application of genetic analysis, is revealing the complex relationships between primary immunodeficiency syndromes and autoimmune diseases. Single-gene defects can cause rare diseases that predominantly present with autoimmune symptoms. Such genetic defects also predispose individuals to recurrent infections (a hallmark of immunodeficiency) and can cause primary immunodeficiencies, which can also lead to immune dysregulation and autoimmunity. Moreover, risk factors for polygenic rheumatic diseases often exist in the same genes as the mutations that give rise to primary immunodeficiency syndromes. In this Review, various primary immunodeficiency syndromes are presented, along with their pathogenetic mechanisms and relationship to autoimmune diseases, in an effort to increase awareness of immunodeficiencies that occur concurrently with autoimmune diseases and to highlight the need to initiate appropriate genetic tests. The growing knowledge of various genetically determined pathologic mechanisms in patients with immunodeficiencies who have autoimmune symptoms opens up new avenues for personalized molecular therapies that could potentially treat immunodeficiency and autoimmunity at the same time, and that could be further explored in the context of autoimmune rheumatic diseases.

Complex Genetics and the Etiology of Human Congenital Heart Disease

PubMed Central

Gelb, Bruce D.; Chung, Wendy K.

2014-01-01

Congenital heart disease (CHD) is the most common birth defect. Despite considerable advances in care, CHD remains a major contributor to newborn mortality and is associated with substantial morbidities and premature death. Genetic abnormalities appear to be the primary cause of CHD, but identifying precise defects has proven challenging, principally because CHD is a complex genetic trait. Mainly because of recent advances in genomic technology such as next-generation DNA sequencing, scientists have begun to identify the genetic variants underlying CHD. In this article, the roles of modifier genes, de novo mutations, copy number variants, common variants, and noncoding mutations in the pathogenesis of CHD are reviewed. PMID:24985128

Kindler syndrome pathogenesis and fermitin family homologue 1 (kindlin-1) function.

PubMed

D'Souza, Maria-Anna M A; Kimble, Roy M; McMillan, James R

2010-01-01

Kindler syndrome is caused by genetic defects in the focal contact-associated protein, fermitin family homologue 1 (FFH1), encoded by the gene FERMT1 (known as KIND1). Defects in FFH1 lead to abnormal integrin activation and loss of keratinocyte epidermal adhesion to the underlying basal lamina, disruption in normal cell cytoskeleton within keratinocytes, and altered signaling pathways, leading to increased extracellular matrix production. Null mutations in FERMT1 result in skin blistering from birth and early childhood progressive poikiloderma, mucosal fragility, and increased risk of cancer. The complete range of FFH1 functions in skin and other epithelia has yet to be determined.

Fragile X syndrome neurobiology translates into rational therapy.

PubMed

Braat, Sien; Kooy, R Frank

2014-04-01

Causal genetic defects have been identified for various neurodevelopmental disorders. A key example in this respect is fragile X syndrome, one of the most frequent genetic causes of intellectual disability and autism. Since the discovery of the causal gene, insights into the underlying pathophysiological mechanisms have increased exponentially. Over the past years, defects were discovered in pathways that are potentially amendable by pharmacological treatment. These findings have inspired the initiation of clinical trials in patients. The targeted pathways converge in part with those of related neurodevelopmental disorders raising hopes that the treatments developed for this specific disorder might be more broadly applicable. Copyright © 2014 Elsevier Ltd. All rights reserved.

Point mutation in D8C domain of Tamm-Horsfall protein/uromodulin in transgenic mice causes progressive renal damage and hyperuricemia

PubMed Central

Landry, Nichole K.; El-Achkar, Tarek M.; Lieske, John C.

2017-01-01

Hereditary mutations in Tamm-Horsfall protein (THP/uromodulin) gene cause autosomal dominant kidney diseases characterized by juvenile-onset hyperuricemia, gout and progressive kidney failure, although the disease pathogenesis remains unclear. Here we show that targeted expression in transgenic mice of a mutation within the domain of 8 cysteines of THP in kidneys’ thick ascending limb (TAL) caused unfolded protein response in younger (1-month old) mice and apoptosis in older (12-month old) mice. While the young mice had urine concentration defects and polyuria, such defects progressively reversed in the older mice to marked oliguria, highly concentrated urine, fibrotic kidneys and reduced creatinine clearance. Both the young and the old transgenic mice had significantly higher serum uric acid and its catabolic product, allantoin, than age-matched wild-type mice. This THP mutation apparently caused primary defects in TAL by compromising the luminal translocation and reabsorptive functions of NKCC2 and ROMK and secondary responses in proximal tubules by upregulating NHE3 and URAT1. Our results strongly suggest that the progressive worsening of kidney functions reflects the accumulation of the deleterious effects of the misfolded mutant THP and the compensatory responses. Transgenic mice recapitulating human THP/uromodulin-associated kidney diseases could be used to elucidate their pathogenesis and test novel therapeutic strategies. PMID:29145399

Point mutation in D8C domain of Tamm-Horsfall protein/uromodulin in transgenic mice causes progressive renal damage and hyperuricemia.

PubMed

Ma, Lijie; Liu, Yan; Landry, Nichole K; El-Achkar, Tarek M; Lieske, John C; Wu, Xue-Ru

2017-01-01

Hereditary mutations in Tamm-Horsfall protein (THP/uromodulin) gene cause autosomal dominant kidney diseases characterized by juvenile-onset hyperuricemia, gout and progressive kidney failure, although the disease pathogenesis remains unclear. Here we show that targeted expression in transgenic mice of a mutation within the domain of 8 cysteines of THP in kidneys' thick ascending limb (TAL) caused unfolded protein response in younger (1-month old) mice and apoptosis in older (12-month old) mice. While the young mice had urine concentration defects and polyuria, such defects progressively reversed in the older mice to marked oliguria, highly concentrated urine, fibrotic kidneys and reduced creatinine clearance. Both the young and the old transgenic mice had significantly higher serum uric acid and its catabolic product, allantoin, than age-matched wild-type mice. This THP mutation apparently caused primary defects in TAL by compromising the luminal translocation and reabsorptive functions of NKCC2 and ROMK and secondary responses in proximal tubules by upregulating NHE3 and URAT1. Our results strongly suggest that the progressive worsening of kidney functions reflects the accumulation of the deleterious effects of the misfolded mutant THP and the compensatory responses. Transgenic mice recapitulating human THP/uromodulin-associated kidney diseases could be used to elucidate their pathogenesis and test novel therapeutic strategies.

Altered surfactant homeostasis and recurrent respiratory failure secondary to TTF-1 nuclear targeting defect.

PubMed

Peca, Donatella; Petrini, Stefania; Tzialla, Chryssoula; Boldrini, Renata; Morini, Francesco; Stronati, Mauro; Carnielli, Virgilio P; Cogo, Paola E; Danhaive, Olivier

2011-08-25

Mutations of genes affecting surfactant homeostasis, such as SFTPB, SFTPC and ABCA3, lead to diffuse lung disease in neonates and children. Haploinsufficiency of NKX2.1, the gene encoding the thyroid transcription factor-1 (TTF-1)--critical for lung, thyroid and central nervous system morphogenesis and function--causes a rare form of progressive respiratory failure designated brain-lung-thyroid syndrome. Molecular mechanisms involved in this syndrome are heterogeneous and poorly explored. We report a novel TTF-1 molecular defect causing recurrent respiratory failure episodes in an infant. The subject was an infant with severe neonatal respiratory distress syndrome followed by recurrent respiratory failure episodes, hypopituitarism and neurological abnormalities. Lung histology and ultrastructure were assessed by surgical biopsy. Surfactant-related genes were studied by direct genomic DNA sequencing and array chromatine genomic hybridization (aCGH). Surfactant protein expression in lung tissue was analyzed by confocal immunofluorescence microscopy. For kinetics studies, surfactant protein B and disaturated phosphatidylcholine (DSPC) were isolated from serial tracheal aspirates after intravenous administration of stable isotope-labeled (2)H(2)O and (13)C-leucine; fractional synthetic rate was derived from gas chromatography/mass spectrometry (2)H and (13)C enrichment curves. Six intubated infants with no primary lung disease were used as controls. Lung biopsy showed desquamative interstitial pneumonitis and lamellar body abnormalities suggestive of genetic surfactant deficiency. Genetic studies identified a heterozygous ABCA3 mutation, L941P, previously unreported. No SFTPB, SFTPC or NKX2.1 mutations or deletions were found. However, immunofluorescence studies showed TTF-1 prevalently expressed in type II cell cytoplasm instead of nucleus, indicating defective nuclear targeting. This pattern has not been reported in human and was not found in two healthy controls and in five ABCA3 mutation carriers. Kinetic studies demonstrated a marked reduction of SP-B synthesis (43.2 vs. 76.5 ± 24.8%/day); conversely, DSPC synthesis was higher (12.4 vs. 6.3 ± 0.5%/day) compared to controls, although there was a marked reduction of DSPC content in tracheal aspirates (29.8 vs. 56.1 ± 12.4% of total phospholipid content). Defective TTF-1 signaling may result in profound surfactant homeostasis disruption and neonatal/pediatric diffuse lung disease. Heterozygous ABCA3 missense mutations may act as disease modifiers in other genetic surfactant defects.

Altered surfactant homeostasis and recurrent respiratory failure secondary to TTF-1 nuclear targeting defect

PubMed Central

2011-01-01

Background Mutations of genes affecting surfactant homeostasis, such as SFTPB, SFTPC and ABCA3, lead to diffuse lung disease in neonates and children. Haploinsufficiency of NKX2.1, the gene encoding the thyroid transcription factor-1 (TTF-1) - critical for lung, thyroid and central nervous system morphogenesis and function - causes a rare form of progressive respiratory failure designated brain-lung-thyroid syndrome. Molecular mechanisms involved in this syndrome are heterogeneous and poorly explored. We report a novel TTF-1 molecular defect causing recurrent respiratory failure episodes in an infant. Methods The subject was an infant with severe neonatal respiratory distress syndrome followed by recurrent respiratory failure episodes, hypopituitarism and neurological abnormalities. Lung histology and ultrastructure were assessed by surgical biopsy. Surfactant-related genes were studied by direct genomic DNA sequencing and array chromatine genomic hybridization (aCGH). Surfactant protein expression in lung tissue was analyzed by confocal immunofluorescence microscopy. For kinetics studies, surfactant protein B and disaturated phosphatidylcholine (DSPC) were isolated from serial tracheal aspirates after intravenous administration of stable isotope-labeled 2H2O and 13C-leucine; fractional synthetic rate was derived from gas chromatography/mass spectrometry 2H and 13C enrichment curves. Six intubated infants with no primary lung disease were used as controls. Results Lung biopsy showed desquamative interstitial pneumonitis and lamellar body abnormalities suggestive of genetic surfactant deficiency. Genetic studies identified a heterozygous ABCA3 mutation, L941P, previously unreported. No SFTPB, SFTPC or NKX2.1 mutations or deletions were found. However, immunofluorescence studies showed TTF-1 prevalently expressed in type II cell cytoplasm instead of nucleus, indicating defective nuclear targeting. This pattern has not been reported in human and was not found in two healthy controls and in five ABCA3 mutation carriers. Kinetic studies demonstrated a marked reduction of SP-B synthesis (43.2 vs. 76.5 ± 24.8%/day); conversely, DSPC synthesis was higher (12.4 vs. 6.3 ± 0.5%/day) compared to controls, although there was a marked reduction of DSPC content in tracheal aspirates (29.8 vs. 56.1 ± 12.4% of total phospholipid content). Conclusion Defective TTF-1 signaling may result in profound surfactant homeostasis disruption and neonatal/pediatric diffuse lung disease. Heterozygous ABCA3 missense mutations may act as disease modifiers in other genetic surfactant defects. PMID:21867529

Amelogenin signal peptide mutation: Correlation between mutations in the amelogenin gene (AMGX) and manifestations of X-linked amelogenesis imperfecta

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lagerstroem-Fermer, M.; Nilsson, M.; Pettersson, U.

1995-03-01

Formation of tooth enamel is a poorly understood biological process. In this study the authors describe a 9-bp deletion in exon 2 of the amelogenin gene (AMGX) causing X-linked hypoplastic amelogenesis imperfecta, a disease characterized by defective enamel. The mutation results in the loss of 3 amino acids and exchange of 1 in the signal peptide of the amelogenin protein. This deletion in the signal peptide probably interferes with translocation of the amelogenin protein during synthesis, resulting in the thin enamel observed in affected members of the family. The authors compare this mutation to a previously reported mutation in themore » amelogenin gene that causes a different disease phenotype. The study illustrates that molecular analysis can help explain the various manifestations of a tooth disorder and thereby provide insights into the mechanisms of tooth enamel formation. 16 refs., 2 figs., 1 tab.« less

nfi-1 affects behavior and life-span in C. elegans but is not essential for DNA replication or survival

PubMed Central

Lazakovitch, Elena; Kalb, John M; Matsumoto, Reiko; Hirono, Keiko; Kohara, Yuji; Gronostajski, Richard M

2005-01-01

Background The Nuclear Factor I (one) (NFI) family of transcription/replication factors plays essential roles in mammalian gene expression and development and in adenovirus DNA replication. Because of its role in viral DNA replication NFI has long been suspected to function in host DNA synthesis. Determining the requirement for NFI proteins in mammalian DNA replication is complicated by the presence of 4 NFI genes in mice and humans. Loss of individual NFI genes in mice cause defects in brain, lung and tooth development, but the presence of 4 homologous NFI genes raises the issue of redundant roles for NFI genes in DNA replication. No NFI genes are present in bacteria, fungi or plants. However single NFI genes are present in several simple animals including Drosophila and C. elegans, making it possible to test for a requirement for NFI in multicellular eukaryotic DNA replication and development. Here we assess the functions of the single nfi-1 gene in C. elegans. Results C. elegans NFI protein (CeNFI) binds specifically to the same NFI-binding site recognized by vertebrate NFIs. nfi-1 encodes alternatively-spliced, maternally-inherited transcripts that are expressed at the single cell stage, during embryogenesis, and in adult muscles, neurons and gut cells. Worms lacking nfi-1 survive but have defects in movement, pharyngeal pumping and egg-laying and have a reduced life-span. Expression of the muscle gene Ce titin is decreased in nfi-1 mutant worms. Conclusion NFI gene function is not needed for survival in C. elegans and thus NFI is likely not essential for DNA replication in multi-cellular eukaryotes. The multiple defects in motility, egg-laying, pharyngeal pumping, and reduced lifespan indicate that NFI is important for these processes. Reduction in Ce titin expression could affect muscle function in multiple tissues. The phenotype of nfi-1 null worms indicates that NFI functions in multiple developmental and behavioral systems in C. elegans, likely regulating genes that function in motility, egg-laying, pharyngeal pumping and lifespan maintenance. PMID:16242019

Hypomorphic mutations in TRNT1 cause retinitis pigmentosa with erythrocytic microcytosis

PubMed Central

DeLuca, Adam P.; Whitmore, S. Scott; Barnes, Jenna; Sharma, Tasneem P.; Westfall, Trudi A.; Scott, C. Anthony; Weed, Matthew C.; Wiley, Jill S.; Wiley, Luke A.; Johnston, Rebecca M.; Schnieders, Michael J.; Lentz, Steven R.; Tucker, Budd A.; Mullins, Robert F.; Scheetz, Todd E.; Stone, Edwin M.; Slusarski, Diane C.

2016-01-01

Retinitis pigmentosa (RP) is a highly heterogeneous group of disorders characterized by degeneration of the retinal photoreceptor cells and progressive loss of vision. While hundreds of mutations in more than 100 genes have been reported to cause RP, discovering the causative mutations in many patients remains a significant challenge. Exome sequencing in an individual affected with non-syndromic RP revealed two plausibly disease-causing variants in TRNT1, a gene encoding a nucleotidyltransferase critical for tRNA processing. A total of 727 additional unrelated individuals with molecularly uncharacterized RP were completely screened for TRNT1 coding sequence variants, and a second family was identified with two members who exhibited a phenotype that was remarkably similar to the index patient. Inactivating mutations in TRNT1 have been previously shown to cause a severe congenital syndrome of sideroblastic anemia, B-cell immunodeficiency, recurrent fevers and developmental delay (SIFD). Complete blood counts of all three of our patients revealed red blood cell microcytosis and anisocytosis with only mild anemia. Characterization of TRNT1 in patient-derived cell lines revealed reduced but detectable TRNT1 protein, consistent with partial function. Suppression of trnt1 expression in zebrafish recapitulated several features of the human SIFD syndrome, including anemia and sensory organ defects. When levels of trnt1 were titrated, visual dysfunction was found in the absence of other phenotypes. The visual defects in the trnt1-knockdown zebrafish were ameliorated by the addition of exogenous human TRNT1 RNA. Our findings indicate that hypomorphic TRNT1 mutations can cause a recessive disease that is almost entirely limited to the retina. PMID:26494905

Persistent activation of Nrf2 through p62 in hepatocellular carcinoma cells

PubMed Central

Inami, Yoshihiro; Waguri, Satoshi; Sakamoto, Ayako; Kouno, Tsuguka; Nakada, Kazuto; Hino, Okio; Watanabe, Sumio; Ando, Jin; Iwadate, Manabu; Yamamoto, Masayuki; Lee, Myung-Shik; Tanaka, Keiji

2011-01-01

Suppression of autophagy is always accompanied by marked accumulation of p62, a selective autophagy substrate. Because p62 interacts with the Nrf2-binding site on Keap1, which is a Cullin 3–based ubiquitin ligase adapter protein, autophagy deficiency causes competitive inhibition of the Nrf2–Keap1 interaction, resulting in stabilization of Nrf2 followed by transcriptional activation of Nrf2 target genes. Herein, we show that liver-specific autophagy-deficient mice harbor adenomas linked to both the formation of p62- and Keap1-positive cellular aggregates and induction of Nrf2 targets. Importantly, similar aggregates were identified in more than 25% of human hepatocellular carcinomas (HCC), and induction of Nrf2 target genes was recognized in most of these tumors. Gene targeting of p62 in an HCC cell line markedly abrogates the anchorage-independent growth, whereas forced expression of p62, but not a Keap1 interaction-defective mutant, resulted in recovery of the growth defect. These results indicate the involvement of persistent activation of Nrf2 through the accumulation of p62 in hepatoma development. PMID:21482715

Frizzled 1 and frizzled 2 genes function in palate, ventricular septum and neural tube closure: general implications for tissue fusion processes

PubMed Central

Yu, Huimin; Smallwood, Philip M.; Wang, Yanshu; Vidaltamayo, Roman; Reed, Randall; Nathans, Jeremy

2010-01-01

The closure of an open anatomical structure by the directed growth and fusion of two tissue masses is a recurrent theme in mammalian embryology, and this process plays an integral role in the development of the palate, ventricular septum, neural tube, urethra, diaphragm and eye. In mice, targeted mutations of the genes encoding frizzled 1 (Fz1) and frizzled 2 (Fz2) show that these highly homologous integral membrane receptors play an essential and partially redundant role in closure of the palate and ventricular septum, and in the correct positioning of the cardiac outflow tract. When combined with a mutant allele of the planar cell polarity gene Vangl2 (Vangl2Lp), Fz1 and/or Fz2 mutations also cause defects in neural tube closure and misorientation of inner ear sensory hair cells. These observations indicate that frizzled signaling is involved in diverse tissue closure processes, defects in which account for some of the most common congenital anomalies in humans. PMID:20940229

Decreased cohesin in the brain leads to defective synapse development and anxiety-related behavior

PubMed Central

Fujita, Yuki; Masuda, Koji; Bando, Masashige; Nakato, Ryuichiro; Katou, Yuki; Tanaka, Takashi; Nakayama, Masahiro; Takao, Keizo; Miyakawa, Tsuyoshi; Tanaka, Tatsunori; Ago, Yukio

2017-01-01

Abnormal epigenetic regulation can cause the nervous system to develop abnormally. Here, we sought to understand the mechanism by which this occurs by investigating the protein complex cohesin, which is considered to regulate gene expression and, when defective, is associated with higher-level brain dysfunction and the developmental disorder Cornelia de Lange syndrome (CdLS). We generated conditional Smc3-knockout mice and observed greater dendritic complexity and larger numbers of immature synapses in the cerebral cortex of Smc3+/− mice. Smc3+/− mice also exhibited more anxiety-related behavior, which is a symptom of CdLS. Further, a gene ontology analysis after RNA-sequencing suggested the enrichment of immune processes, particularly the response to interferons, in the Smc3+/− mice. Indeed, fewer synapses formed in their cortical neurons, and this phenotype was rescued by STAT1 knockdown. Thus, low levels of cohesin expression in the developing brain lead to changes in gene expression that in turn lead to a specific and abnormal neuronal and behavioral phenotype. PMID:28408410

Structural Analysis on the Pathologic Mutant Glucocorticoid Receptor Ligand-Binding Domains.

PubMed

Hurt, Darrell E; Suzuki, Shigeru; Mayama, Takafumi; Charmandari, Evangelia; Kino, Tomoshige

2016-02-01

Glucocorticoid receptor (GR) gene mutations may cause familial or sporadic generalized glucocorticoid resistance syndrome. Most of the missense forms distribute in the ligand-binding domain and impair its ligand-binding activity and formation of the activation function (AF)-2 that binds LXXLL motif-containing coactivators. We performed molecular dynamics simulations to ligand-binding domain of pathologic GR mutants to reveal their structural defects. Several calculated parameters including interaction energy for dexamethasone or the LXXLL peptide indicate that destruction of ligand-binding pocket (LBP) is a primary character. Their LBP defects are driven primarily by loss/reduction of the electrostatic interaction formed by R611 and T739 of the receptor to dexamethasone and a subsequent conformational mismatch, which deacylcortivazol resolves with its large phenylpyrazole moiety and efficiently stimulates transcriptional activity of the mutant receptors with LBP defect. Reduced affinity of the LXXLL peptide to AF-2 is caused mainly by disruption of the electrostatic bonds to the noncore leucine residues of this peptide that determine the peptide's specificity to GR, as well as by reduced noncovalent interaction against core leucines and subsequent exposure of the AF-2 surface to solvent. The results reveal molecular defects of pathologic mutant receptors and provide important insights to the actions of wild-type GR.

The C. elegans histone deacetylase HDA-1 is required for cell migration and axon pathfinding.

PubMed

Zinovyeva, Anna Y; Graham, Serena M; Cloud, Veronica J; Forrester, Wayne C

2006-01-01

Histone proteins play integral roles in chromatin structure and function. Histones are subject to several types of posttranslational modifications, including acetylation, which can produce transcriptional activation. The converse, histone deacetylation, is mediated by histone deacetylases (HDACs) and often is associated with transcriptional silencing. We identified a new mutation, cw2, in the Caenorhabditis elegans hda-1 gene, which encodes a histone deacetylase. Previous studies showed that a mutation in hda-1, e1795, or reduction of hda-1 RNA by RNAi causes defective vulval and gonadal development leading to sterility. The hda-1(cw2) mutation causes defective vulval development and reduced fertility, like hda-1(e1795), albeit with reduced severity. Unlike the previously reported hda-1 mutation, hda-1(cw2) mutants are viable as homozygotes, although many die as embryos or larvae, and are severely uncoordinated. Strikingly, in hda-1(cw2) mutants, axon pathfinding is defective; specific axons often appear to wander randomly or migrate in the wrong direction. In addition, the long range migrations of three neuron types and fasciculation of the ventral nerve cord are defective. Together, our studies define a new role for HDA-1 in nervous system development, and provide the first evidence for HDAC function in regulating neuronal axon guidance.

Increasing cholesterol synthesis in 7-dehydrosterol reductase (DHCR7) deficient mouse models through gene transfer

PubMed Central

Matabosch, Xavier; Ying, Lee; Serra, Montserrat; Wassif, Christopher A.; Porter, Forbes D.; Shackleton, Cedric; Watson, Gordon

2010-01-01

Smith-Lemli-Opitz syndrome (SLOS) is caused by deficiency in the terminal step of cholesterol biosynthesis: the conversion of 7-dehydrocholesterol (7DHC) to cholesterol (C), catalyzed by 7-dehydrocholesterol reductase (DHCR7). This disorder exhibits several phenotypic traits including dysmorphia and mental retardation with a broad range of severity. There are few proven treatment options. That most commonly used is a high cholesterol diet that seems to enhance the quality of life and improve behavioral characteristics of patients, although these positive effects are controversial. The goal of our study was to investigate the possibility of restoring DHCR7 activity by gene transfer. We constructed an adeno-associated virus (AAV) vector containing the DHCR7 gene. After we infused this vector into affected mice, the introduced DHCR7 gene could be identified in liver, mRNA was expressed and a functional enzyme was produced. Evidence of functionality came from the ability to partially normalize the serum ratio of 7DHC/C in treated animals, apparently by increasing cholesterol production with concomitant decrease in 7DHC precursor. By five weeks after treatment the mean ratio (for 7 animals) had fallen to 0.05 while the ratio for untreated littermate controls had risen to 0.14. This provides proof of principle that gene transfer can ameliorate the genetic defect causing SLOS and provides a new experimental tool for studying the pathogenesis of this disease. If effective in humans, it might also offer a possible alternative to exogenous cholesterol therapy. However, it would not offer a complete cure for the disorder as many of the negative implications of defective synthesis are already established during prenatal development. PMID:20800683

Clinical heterogeneity within xeroderma pigmentosum associated with mutations in the DNA repair and transcription gene ERCC3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vermeulen, W.; Kleijer, W.J.; Bootsma, D.

1994-02-01

The human DNA excision repair gene ERCC3 specifically corrects the nucleotide excision repair (NER) defect of xeroderma pigmentosum (XP) complementation group B. In addition to its function in NER, the ERCC3 DNA helicase was recently identified as one of the components of the human BTF2/TFIIH transcription factor complex, which is required for initiation of transcription of class II genes. To date, a single patient (XP11BE) has been assigned to this XP group B (XP-B), with the remarkable conjunction of two autosomal recessive DNA repair deficiency disorders: XP and Cockayne syndrome (CS). The intriguing involvement of the ERCC3 protein in themore » vital process of transcription may provide an explanation for the rarity, severity, and wide spectrum of clinical features in this complementation group. Here the authors report the identification of two new XP-B patients: XPCS1BA and XPCS2BA (siblings), by microneedle injection of the cloned ERCC3 repair gene as well as by cell hybridization. Molecular analysis of the ERCC3 gene in both patients revealed a single base substitution causing a missense mutation in a region that is completely conserved in yeast, Drosophila, mouse, and human ERCC3. As in patient XP11BE, the expression of only one allele (paternal) is detected. The mutation causes a virtually complete inactivation of the NER function of the protein. Despite this severe NER defect, both patients display a late onset of neurologic impairment, mild cutaneous symptoms, and a striking absence of skin tumors even at an age of >40 years. Analysis of the frequency of hprt[sup [minus

Histopathological Comparison between Bone Marrow- and Periodontium-derived Stem Cells for Bone Regeneration in Rabbit Calvaria.

PubMed

Kadkhoda, Z; Safarpour, A; Azmoodeh, F; Adibi, S; Khoshzaban, A; Bahrami, N

2016-01-01

Periodontitis is an important oral disease. Stem cell therapy has found its way in treatment of many diseases. To evaluate the regenerative potential of periodontal ligament-derived stem cells (PDLSCs) and osteoblast differentiated from PDLSC in comparison with bone marrow-derived mesenchymal stem cells (BM-MSCs) and pre-osteoblasts in calvarial defects. After proving the existence of surface markers by flow cytometry, BM-MSCs were differentiated into osteoblasts. 5 defects were made on rabbit calvaria. 3 of them were first covered with collagen membrane and then with BM-MSCs, PDLSCs, and pre-osteoblasts. The 4(th) defect was filled with collagen membrane and the 5(th) one was served as control. After 4 weeks, histological (quantitative) and histomorphological (qualitative) surveys were performed. Both cell lineages were positive for CD-90 cell marker, which was specifically related to stem cells. Alizarin red staining was done for showing mineral material. RT-PCR set up for the expression of Cbfa1 gene, BMP4 gene, and PGLAP gene, confirmed osteoblast differentiation. The findings indicated that although PDLSCs and pre-osteoblasts could be used for bone regeneration, the rate of regeneration in BM-MSCs-treated cavities was more significant (p<0.0001). The obtained results are probably attributable to the effective micro-environmental signals caused by different bone types and the rate of cell maturation.

Proposal for a new therapy for drug-resistant malaria using Plasmodium synthetic lethality inference.

PubMed

Lee, Sang Joon; Seo, Eunseok; Cho, Yonghyun

2013-12-01

Many antimalarial drugs kill malaria parasites, but antimalarial drug resistance (ADR) and toxicity to normal cells limit their usefulness. To solve this problem, we suggest a new therapy for drug-resistant malaria. The approach consists of data integration and inference through homology analysis of yeast-human-Plasmodium. If one gene of a Plasmodium synthetic lethal (SL) gene pair has a mutation that causes ADR, a drug targeting the other gene of the SL pair might be used as an effective treatment for drug-resistant strains of malaria. A simple computational tool to analyze the inferred SL genes of Plasmodium species (malaria parasites Plasmodium falciparum and Plasmodium vivax for human malarial therapy, and rodent parasite Plasmodium berghei for in vivo studies of human malarias) was established to identify SL genes that can be used as drug targets. Information on SL gene pairs with ADR genes and their first neighbors was inferred from yeast SL genes to search for pertinent antimalarial drug targets. We not only suggest drug target gene candidates for further experimental validation, but also provide information on new usage for already-described drugs. The proposed specific antimalarial drug candidates can be inferred by searching drugs that cause a fitness defect in yeast SL genes.

SpliceDisease database: linking RNA splicing and disease.

PubMed

Wang, Juan; Zhang, Jie; Li, Kaibo; Zhao, Wei; Cui, Qinghua

2012-01-01

RNA splicing is an important aspect of gene regulation in many organisms. Splicing of RNA is regulated by complicated mechanisms involving numerous RNA-binding proteins and the intricate network of interactions among them. Mutations in cis-acting splicing elements or its regulatory proteins have been shown to be involved in human diseases. Defects in pre-mRNA splicing process have emerged as a common disease-causing mechanism. Therefore, a database integrating RNA splicing and disease associations would be helpful for understanding not only the RNA splicing but also its contribution to disease. In SpliceDisease database, we manually curated 2337 splicing mutation disease entries involving 303 genes and 370 diseases, which have been supported experimentally in 898 publications. The SpliceDisease database provides information including the change of the nucleotide in the sequence, the location of the mutation on the gene, the reference Pubmed ID and detailed description for the relationship among gene mutations, splicing defects and diseases. We standardized the names of the diseases and genes and provided links for these genes to NCBI and UCSC genome browser for further annotation and genomic sequences. For the location of the mutation, we give direct links of the entry to the respective position/region in the genome browser. The users can freely browse, search and download the data in SpliceDisease at http://cmbi.bjmu.edu.cn/sdisease.

The Chicken Frizzle Feather Is Due to an α-Keratin (KRT75) Mutation That Causes a Defective Rachis

PubMed Central

Foley, John; Foley, Anne; McDonald, Merry-Lynn; Juan, Wen-Tau; Huang, Chih-Jen; Lai, Yu-Ting; Lo, Wen-Sui; Chen, Chih-Feng; Leal, Suzanne M.; Zhang, Huanmin; Widelitz, Randall B.; Patel, Pragna I.; Li, Wen-Hsiung; Chuong, Cheng-Ming

2012-01-01

Feathers have complex forms and are an excellent model to study the development and evolution of morphologies. Existing chicken feather mutants are especially useful for identifying genetic determinants of feather formation. This study focused on the gene F, underlying the frizzle feather trait that has a characteristic curled feather rachis and barbs in domestic chickens. Our developmental biology studies identified defects in feather medulla formation, and physical studies revealed that the frizzle feather curls in a stepwise manner. The frizzle gene is transmitted in an autosomal incomplete dominant mode. A whole-genome linkage scan of five pedigrees with 2678 SNPs revealed association of the frizzle locus with a keratin gene-enriched region within the linkage group E22C19W28_E50C23. Sequence analyses of the keratin gene cluster identified a 69 bp in-frame deletion in a conserved region of KRT75, an α-keratin gene. Retroviral-mediated expression of the mutated F cDNA in the wild-type rectrix qualitatively changed the bending of the rachis with some features of frizzle feathers including irregular kinks, severe bending near their distal ends, and substantially higher variations among samples in comparison to normal feathers. These results confirmed KRT75 as the F gene. This study demonstrates the potential of our approach for identifying genetic determinants of feather forms. PMID:22829773

Wnt signaling in caudal dysgenesis and diabetic embryopathy

PubMed Central

Pavlinkova, Gabriela; Salbaum, J. Michael; Kappen, Claudia

2010-01-01

Congenital defects are a major complication of diabetic pregnancy, and the leading cause of infant death in the first year of life. Caudal dysgenesis, occurring up to 200-fold more frequently in children born to diabetic mothers, is a hallmark of diabetic pregnancy. Given that there is also an at least 3-fold higher risk for heart defects and neural tube defects, it is important to identify the underlying molecular mechanisms for aberrant embryonic development. We have investigated gene expression in a transgenic mouse model of caudal dysgenesis, and in a pharmacological model using situ hybridization and quantitative real-time PCR. We identify altered expression of several molecules that control developmental processes and embryonic growth. The results from our models point towards major implication of altered Wnt signaling in the pathogenesis of developmental anomalies associated with embryonic exposure to maternal diabetes. PMID:18937363

Mutations in STN1 cause Coats plus syndrome and are associated with genomic and telomere defects

PubMed Central

Simon, Amos J.; Lev, Atar; Zhang, Yong; Weiss, Batia; Rylova, Anna; Eyal, Eran; Kol, Nitzan; Cesarkas, Keren; Rhodes, Michele; Schiby, Ginette; Barshack, Iris; Katz, Shulamit; Reznik-Wolf, Haike; Ribakovsky, Elena; Simon, Carlos; Hazou, Wadi; Katzir, Hagar; Sagie, Shira; Amariglio, Ninette; Rechavi, Gideon

2016-01-01

The analysis of individuals with telomere defects may shed light on the delicate interplay of factors controlling genome stability, premature aging, and cancer. We herein describe two Coats plus patients with telomere and genomic defects; both harbor distinct, novel mutations in STN1, a member of the human CTC1–STN1–TEN1 (CST) complex, thus linking this gene for the first time to a human telomeropathy. We characterized the patients’ phenotype, recapitulated it in a zebrafish model and rescued cellular and clinical aspects by the ectopic expression of wild-type STN1 or by thalidomide treatment. Interestingly, a significant lengthy control of the gastrointestinal bleeding in one of our patients was achieved by thalidomide treatment, exemplifying a successful bed-to-bench-and-back approach. PMID:27432940

Epstein–Barr Virus Susceptibility in Activated PI3Kδ Syndrome (APDS) Immunodeficiency

PubMed Central

Carpier, Jean-Marie; Lucas, Carrie L.

2018-01-01

Activated PI3Kδ Syndrome (APDS) is an inherited immune disorder caused by heterozygous, gain-of-function mutations in the genes encoding the phosphoinositide 3-kinase delta (PI3Kδ) subunits p110δ or p85δ. This recently described primary immunodeficiency disease (PID) is characterized by recurrent sinopulmonary infections, lymphoproliferation, and susceptibility to herpesviruses, with Epstein–Barr virus (EBV) infection being most notable. A broad range of PIDs having disparate, molecularly defined genetic etiology can cause susceptibility to EBV, lymphoproliferative disease, and lymphoma. Historically, PID patients with loss-of-function mutations causing defective cell-mediated cytotoxicity or antigen receptor signaling were found to be highly susceptible to pathological EBV infection. By contrast, the gain of function in PI3K signaling observed in APDS patients paradoxically renders these patients susceptible to EBV, though the underlying mechanisms are incompletely understood. At a cellular level, APDS patients exhibit deranged B lymphocyte development and defects in class switch recombination, which generally lead to defective immunoglobulin production. Moreover, APDS patients also demonstrate an abnormal skewing of T cells toward terminal effectors with short telomeres and senescence markers. Here, we review APDS with a particular focus on how the altered lymphocyte biology in these patients may confer EBV susceptibility. PMID:29387064

The zebrafish maternal-effect gene cellular atoll encodes the centriolar component sas-6 and defects in its paternal function promote whole genome duplication.

PubMed

Yabe, Taijiro; Ge, Xiaoyan; Pelegri, Francisco

2007-12-01

A female-sterile zebrafish maternal-effect mutation in cellular atoll (cea) results in defects in the initiation of cell division starting at the second cell division cycle. This phenomenon is caused by defects in centrosome duplication, which in turn affect the formation of a bipolar spindle. We show that cea encodes the centriolar coiled-coil protein Sas-6, and that zebrafish Cea/Sas-6 protein localizes to centrosomes. cea also has a genetic paternal contribution, which when mutated results in an arrested first cell division followed by normal cleavage. Our data supports the idea that, in zebrafish, paternally inherited centrosomes are required for the first cell division while maternally derived factors are required for centrosomal duplication and cell divisions in subsequent cell cycles. DNA synthesis ensues in the absence of centrosome duplication, and the one-cycle delay in the first cell division caused by cea mutant sperm leads to whole genome duplication. We discuss the potential implications of these findings with regards to the origin of polyploidization in animal species. In addition, the uncoupling of developmental time and cell division count caused by the cea mutation suggests the presence of a time window, normally corresponding to the first two cell cycles, which is permissive for germ plasm recruitment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruening, W.; Nakagama, H.: Bardessy, N.

Wilms` tumor (WT), an embryonal malignancy of the kidney, occurs most frequently in children under the age of 5 years, affecting {approximately}1 in 10,000 individuals. The WT1 tumor suppressor gene, residing at 11p13, is structurally altered in {approximately}10-15% of WT cases. Individuals with germline mutations within the WT1 gene suffer from predisposition to WT and developmental defects of the urogenital system. Patients with heterozygous deletions of the WT1 gene, or mutations predicted to cause inactivation of one WT1 allele, suffer relatively mild genital system defects (notably hypospadias and cryptorchidism in males) and a predisposition to WT. These results suggest thatmore » developing genital system development is sensitive to the absolute concentrations of the WT1 gene products. Patients with missense mutations within the WT1 gene, however, can suffer from a much more severe disorder known as Denys-Drash syndrome (DDS). This syndrome is characterized by intersex disorders, renal nephropathy, and a predisposition to WTs. The increased severity of the developmental defects associated with DDS, compared to those individuals with mild genital system anomalies and WTs, suggests that mutations defined in patients with DDS behave in a dominant-negative fashion. We have identified a novel WT1 mutation in a patient with DDS. This mutation, predicted to produce a truncated WT1 polypeptide encompassing exons 1, 2, and 3, defines a domain capable of behaving as an antimorph. We have also demonstrated that WT1 can self-associate in vivo using yeast two-hybrid systems. Deletion analysis have mapped the interacting domains to the amino terminus of the WT1 polypeptide, within exons 1 and 2. These results provide a molecular mechanism to explain how WT1 mutations can function in a dominant-negative fashion to eliminate wild-type WT1 activity, leading to DDS.« less

Transcriptome Profiling Identifies Multiplexin as a Target of SAGA Deubiquitinase Activity in Glia Required for Precise Axon Guidance During Drosophila Visual Development.

PubMed

Ma, Jingqun; Brennan, Kaelan J; D'Aloia, Mitch R; Pascuzzi, Pete E; Weake, Vikki M

2016-08-09

The Spt-Ada-Gcn5 Acetyltransferase (SAGA) complex is a transcriptional coactivator with histone acetylase and deubiquitinase activities that plays an important role in visual development and function. In Drosophila melanogaster, four SAGA subunits are required for the deubiquitination of monoubiquitinated histone H2B (ubH2B): Nonstop, Sgf11, E(y)2, and Ataxin 7. Mutations that disrupt SAGA deubiquitinase activity cause defects in neuronal connectivity in the developing Drosophila visual system. In addition, mutations in SAGA result in the human progressive visual disorder spinocerebellar ataxia type 7 (SCA7). Glial cells play a crucial role in both the neuronal connectivity defect in nonstop and sgf11 flies, and in the retinal degeneration observed in SCA7 patients. Thus, we sought to identify the gene targets of SAGA deubiquitinase activity in glia in the Drosophila larval central nervous system. To do this, we enriched glia from wild-type, nonstop, and sgf11 larval optic lobes using affinity-purification of KASH-GFP tagged nuclei, and then examined each transcriptome using RNA-seq. Our analysis showed that SAGA deubiquitinase activity is required for proper expression of 16% of actively transcribed genes in glia, especially genes involved in proteasome function, protein folding and axon guidance. We further show that the SAGA deubiquitinase-activated gene Multiplexin (Mp) is required in glia for proper photoreceptor axon targeting. Mutations in the human ortholog of Mp, COL18A1, have been identified in a family with a SCA7-like progressive visual disorder, suggesting that defects in the expression of this gene in SCA7 patients could play a role in the retinal degeneration that is unique to this ataxia. Copyright © 2016 Ma et al.

Activating mutations in RRAS underlie a phenotype within the RASopathy spectrum and contribute to leukaemogenesis

PubMed Central

Flex, Elisabetta; Jaiswal, Mamta; Pantaleoni, Francesca; Martinelli, Simone; Strullu, Marion; Fansa, Eyad K.; Caye, Aurélie; De Luca, Alessandro; Lepri, Francesca; Dvorsky, Radovan; Pannone, Luca; Paolacci, Stefano; Zhang, Si-Cai; Fodale, Valentina; Bocchinfuso, Gianfranco; Rossi, Cesare; Burkitt-Wright, Emma M.M.; Farrotti, Andrea; Stellacci, Emilia; Cecchetti, Serena; Ferese, Rosangela; Bottero, Lisabianca; Castro, Silvana; Fenneteau, Odile; Brethon, Benoît; Sanchez, Massimo; Roberts, Amy E.; Yntema, Helger G.; Van Der Burgt, Ineke; Cianci, Paola; Bondeson, Marie-Louise; Cristina Digilio, Maria; Zampino, Giuseppe; Kerr, Bronwyn; Aoki, Yoko; Loh, Mignon L.; Palleschi, Antonio; Di Schiavi, Elia; Carè, Alessandra; Selicorni, Angelo; Dallapiccola, Bruno; Cirstea, Ion C.; Stella, Lorenzo; Zenker, Martin; Gelb, Bruce D.; Cavé, Hélène; Ahmadian, Mohammad R.; Tartaglia, Marco

2014-01-01

RASopathies, a family of disorders characterized by cardiac defects, defective growth, facial dysmorphism, variable cognitive deficits and predisposition to certain malignancies, are caused by constitutional dysregulation of RAS signalling predominantly through the RAF/MEK/ERK (MAPK) cascade. We report on two germline mutations (p.Gly39dup and p.Val55Met) in RRAS, a gene encoding a small monomeric GTPase controlling cell adhesion, spreading and migration, underlying a rare (2 subjects among 504 individuals analysed) and variable phenotype with features partially overlapping Noonan syndrome, the most common RASopathy. We also identified somatic RRAS mutations (p.Gly39dup and p.Gln87Leu) in 2 of 110 cases of non-syndromic juvenile myelomonocytic leukaemia, a childhood myeloproliferative/myelodysplastic disease caused by upregulated RAS signalling, defining an atypical form of this haematological disorder rapidly progressing to acute myeloid leukaemia. Two of the three identified mutations affected known oncogenic hotspots of RAS genes and conferred variably enhanced RRAS function and stimulus-dependent MAPK activation. Expression of an RRAS mutant homolog in Caenorhabditis elegans enhanced RAS signalling and engendered protruding vulva, a phenotype previously linked to the RASopathy-causing SHOC2S2G mutant. Overall, these findings provide evidence of a functional link between RRAS and MAPK signalling and reveal an unpredicted role of enhanced RRAS function in human disease. PMID:24705357

Rhythm Defects Caused by Newly Engineered Null Mutations in Drosophila's cryptochrome Gene

PubMed Central

Dolezelova, Eva; Dolezel, David; Hall, Jeffrey C.

2007-01-01

Much of the knowledge about cryptochrome function in Drosophila stems from analyzing the cryb mutant. Several features of this variant's light responsiveness imply either that CRYb retains circadian-photoreceptive capacities or that additional CRY-independent light-input routes subserve these processes. Potentially to resolve these issues, we generated cry knock-out mutants (cry0's) by gene replacement. They behaved in an anomalously rhythmic manner in constant light (LL). However, cry0 flies frequently exhibited two separate circadian components in LL, not observed in most previous cryb analyses. Temperature-dependent circadian phenotypes exhibited by cry0 flies suggest that CRY is involved in core pacemaking. Further locomotor experiments combined cry0 with an externally blinding mutation (norpAP24), which caused the most severe decrements of circadian photoreception observed so far. cryb cultures were shown previously to exhibit either aperiodic or rhythmic eclosion in separate studies. We found cry0 to eclose in a solidly periodic manner in light:dark cycles or constant darkness. Furthermore, both cry0 and cryb eclosed rhythmically in LL. These findings indicate that the novel cry0 type causes more profound defects than does the cryb mutation, implying that CRYb retains residual activity. Because some norpAP24 cry0 individuals can resynchronize to novel photic regimes, an as-yet undetermined light-input route exists in Drosophila. PMID:17720919

Genetics and the Quality of Life

ERIC Educational Resources Information Center

Wallace, Bruce

1973-01-01

Knowledge about gene defects (such as the Sickle Cell Gene) should be given to those who show positive laboratory tests. Conflict between gene therapy, aimed at removing the defective gene, and ethical problems should be resolved from the perspective of the effect on future generations. (PS)

Exome-wide Association Study Identifies GREB1L Mutations in Congenital Kidney Malformations.

PubMed

Sanna-Cherchi, Simone; Khan, Kamal; Westland, Rik; Krithivasan, Priya; Fievet, Lorraine; Rasouly, Hila Milo; Ionita-Laza, Iuliana; Capone, Valentina P; Fasel, David A; Kiryluk, Krzysztof; Kamalakaran, Sitharthan; Bodria, Monica; Otto, Edgar A; Sampson, Matthew G; Gillies, Christopher E; Vega-Warner, Virginia; Vukojevic, Katarina; Pediaditakis, Igor; Makar, Gabriel S; Mitrotti, Adele; Verbitsky, Miguel; Martino, Jeremiah; Liu, Qingxue; Na, Young-Ji; Goj, Vinicio; Ardissino, Gianluigi; Gigante, Maddalena; Gesualdo, Loreto; Janezcko, Magdalena; Zaniew, Marcin; Mendelsohn, Cathy Lee; Shril, Shirlee; Hildebrandt, Friedhelm; van Wijk, Joanna A E; Arapovic, Adela; Saraga, Marijan; Allegri, Landino; Izzi, Claudia; Scolari, Francesco; Tasic, Velibor; Ghiggeri, Gian Marco; Latos-Bielenska, Anna; Materna-Kiryluk, Anna; Mane, Shrikant; Goldstein, David B; Lifton, Richard P; Katsanis, Nicholas; Davis, Erica E; Gharavi, Ali G

2017-11-02

Renal agenesis and hypodysplasia (RHD) are major causes of pediatric chronic kidney disease and are highly genetically heterogeneous. We conducted whole-exome sequencing in 202 case subjects with RHD and identified diagnostic mutations in genes known to be associated with RHD in 7/202 case subjects. In an additional affected individual with RHD and a congenital heart defect, we found a homozygous loss-of-function (LOF) variant in SLIT3, recapitulating phenotypes reported with Slit3 inactivation in the mouse. To identify genes associated with RHD, we performed an exome-wide association study with 195 unresolved case subjects and 6,905 control subjects. The top signal resided in GREB1L, a gene implicated previously in Hoxb1 and Shha signaling in zebrafish. The significance of the association, which was p = 2.0 × 10 -5 for novel LOF, increased to p = 4.1 × 10 -6 for LOF and deleterious missense variants combined, and augmented further after accounting for segregation and de novo inheritance of rare variants (joint p = 2.3 × 10 -7 ). Finally, CRISPR/Cas9 disruption or knockdown of greb1l in zebrafish caused specific pronephric defects, which were rescued by wild-type human GREB1L mRNA, but not mRNA containing alleles identified in case subjects. Together, our study provides insight into the genetic landscape of kidney malformations in humans, presents multiple candidates, and identifies SLIT3 and GREB1L as genes implicated in the pathogenesis of RHD. Copyright © 2017 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

Mutations in yeast proliferating cell nuclear antigen define distinct sites for interaction with DNA polymerase delta and DNA polymerase epsilon.

PubMed Central

Eissenberg, J C; Ayyagari, R; Gomes, X V; Burgers, P M

1997-01-01

The importance of the interdomain connector loop and of the carboxy-terminal domain of Saccharomyces cerevisiae proliferating cell nuclear antigen (PCNA) for functional interaction with DNA polymerases delta (Poldelta) and epsilon (Pol epsilon) was investigated by site-directed mutagenesis. Two alleles, pol30-79 (IL126,128AA) in the interdomain connector loop and pol30-90 (PK252,253AA) near the carboxy terminus, caused growth defects and elevated sensitivity to DNA-damaging agents. These two mutants also had elevated rates of spontaneous mutations. The mutator phenotype of pol30-90 was due to partially defective mismatch repair in the mutant. In vitro, the mutant PCNAs showed defects in DNA synthesis. Interestingly, the pol30-79 mutant PCNA (pcna-79) was most defective in replication with Poldelta, whereas pcna-90 was defective in replication with Pol epsilon. Protein-protein interaction studies showed that pcna-79 and pcna-90 failed to interact with Pol delta and Pol epsilon, respectively. In addition, pcna-90 was defective in interaction with the FEN-1 endo-exonuclease (RTH1 product). A loss of interaction between pcna-79 and the smallest subunit of Poldelta, the POL32 gene product, implicates this interaction in the observed defect with the polymerase. Neither PCNA mutant showed a defect in the interaction with replication factor C or in loading by this complex. Processivity of DNA synthesis by the mutant holoenzyme containing pcna-79 was unaffected on poly(dA) x oligo(dT) but was dramatically reduced on a natural template with secondary structure. A stem-loop structure with a 20-bp stem formed a virtually complete block for the holoenzyme containing pcna-79 but posed only a minor pause site for wild-type holoenzyme, indicating a function of the POL32 gene product in allowing replication past structural blocks. PMID:9343398

Next-generation sequencing reveals a novel NDP gene mutation in a Chinese family with Norrie disease.

PubMed

Huang, Xiaoyan; Tian, Mao; Li, Jiankang; Cui, Ling; Li, Min; Zhang, Jianguo

2017-11-01

Norrie disease (ND) is a rare X-linked genetic disorder, the main symptoms of which are congenital blindness and white pupils. It has been reported that ND is caused by mutations in the NDP gene. Although many mutations in NDP have been reported, the genetic cause for many patients remains unknown. In this study, the aim is to investigate the genetic defect in a five-generation family with typical symptoms of ND. To identify the causative gene, next-generation sequencing based target capture sequencing was performed. Segregation analysis of the candidate variant was performed in additional family members using Sanger sequencing. We identified a novel missense variant (c.314C>A) located within the NDP gene. The mutation cosegregated within all affected individuals in the family and was not found in unaffected members. By happenstance, in this family, we also detected a known pathogenic variant of retinitis pigmentosa in a healthy individual. c.314C>A mutation of NDP gene is a novel mutation and broadens the genetic spectrum of ND.

A novel hypothyroid dwarfism due to the missense mutation Arg479Cys of the thyroid peroxidase gene in the mouse.

PubMed

Takabayashi, Shuji; Umeki, Kazumi; Yamamoto, Etsuko; Suzuki, Tohru; Okayama, Akihiko; Katoh, Hideki

2006-10-01

Recently, we found a novel dwarf mutation in an ICR closed colony. This mutation was governed by a single autosomal recessive gene. In novel dwarf mice, plasma levels of the thyroid hormones, T3 and T4, were reduced; however, TSH was elevated. Their thyroid glands showed a diffuse goiter exhibiting colloid deficiency and abnormal follicle epithelium. The dwarfism was improved by adding thyroid hormone in the diet. Gene mapping revealed that the dwarf mutation was closely linked to the thyroid peroxidase (Tpo) gene on chromosome 12. Sequencing of the Tpo gene of the dwarf mice demonstrated a C to T substitution at position 1508 causing an amino acid change from arginine (Arg) to cysteine (Cys) at codon 479 (Arg479Cys). Western blotting revealed that TPO protein of the dwarf mice was detected in a microsomal fraction of thyroid tissue, but peroxidase activity was not detected. These findings suggested that the dwarf mutation caused a primary congenital hypothyroidism by TPO deficiency, resulting in a defect of thyroid hormone synthesis.

Diagnosis and molecular basis of mitochondrial respiratory chain disorders: exome sequencing for disease gene identification.

PubMed

Ohtake, A; Murayama, K; Mori, M; Harashima, H; Yamazaki, T; Tamaru, S; Yamashita, Y; Kishita, Y; Nakachi, Y; Kohda, M; Tokuzawa, Y; Mizuno, Y; Moriyama, Y; Kato, H; Okazaki, Y

2014-04-01

Mitochondrial disorders have the highest incidence among congenital metabolic diseases, and are thought to occur at a rate of 1 in 5000 births. About 25% of the diseases diagnosed as mitochondrial disorders in the field of pediatrics have mitochondrial DNA abnormalities, while the rest occur due to defects in genes encoded in the nucleus. The most important function of the mitochondria is biosynthesis of ATP. Mitochondrial disorders are nearly synonymous with mitochondrial respiratory chain disorder, as respiratory chain complexes serve a central role in ATP biosynthesis. By next-generation sequencing of the exome, we analyzed 104 patients with mitochondrial respiratory chain disorders. The results of analysis to date were 18 patients with novel variants in genes previously reported to be disease-causing, and 27 patients with mutations in genes suggested to be associated in some way with mitochondria, and it is likely that they are new disease-causing genes in mitochondrial disorders. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Seven mutations in the human insulin gene linked to permanent neonatal/infancy-onset diabetes mellitus

PubMed Central

Colombo, Carlo; Porzio, Ottavia; Liu, Ming; Massa, Ornella; Vasta, Mario; Salardi, Silvana; Beccaria, Luciano; Monciotti, Carla; Toni, Sonia; Pedersen, Oluf; Hansen, Torben; Federici, Luca; Pesavento, Roberta; Cadario, Francesco; Federici, Giorgio; Ghirri, Paolo; Arvan, Peter; Iafusco, Dario; Barbetti, Fabrizio

2008-01-01

Permanent neonatal diabetes mellitus (PNDM) is a rare disorder usually presenting within 6 months of birth. Although several genes have been linked to this disorder, in almost half the cases documented in Italy, the genetic cause remains unknown. Because the Akita mouse bearing a mutation in the Ins2 gene exhibits PNDM associated with pancreatic β cell apoptosis, we sequenced the human insulin gene in PNDM subjects with unidentified mutations. We discovered 7 heterozygous mutations in 10 unrelated probands. In 8 of these patients, insulin secretion was detectable at diabetes onset, but rapidly declined over time. When these mutant proinsulins were expressed in HEK293 cells, we observed defects in insulin protein folding and secretion. In these experiments, expression of the mutant proinsulins was also associated with increased Grp78 protein expression and XBP1 mRNA splicing, 2 markers of endoplasmic reticulum stress, and with increased apoptosis. Similarly transfected INS-1E insulinoma cells had diminished viability compared with those expressing WT proinsulin. In conclusion, we find that mutations in the insulin gene that promote proinsulin misfolding may cause PNDM. PMID:18451997

Next-generation sequencing reveals a novel NDP gene mutation in a Chinese family with Norrie disease

PubMed Central

Huang, Xiaoyan; Tian, Mao; Li, Jiankang; Cui, Ling; Li, Min; Zhang, Jianguo

2017-01-01

Purpose: Norrie disease (ND) is a rare X-linked genetic disorder, the main symptoms of which are congenital blindness and white pupils. It has been reported that ND is caused by mutations in the NDP gene. Although many mutations in NDP have been reported, the genetic cause for many patients remains unknown. In this study, the aim is to investigate the genetic defect in a five-generation family with typical symptoms of ND. Methods: To identify the causative gene, next-generation sequencing based target capture sequencing was performed. Segregation analysis of the candidate variant was performed in additional family members using Sanger sequencing. Results: We identified a novel missense variant (c.314C>A) located within the NDP gene. The mutation cosegregated within all affected individuals in the family and was not found in unaffected members. By happenstance, in this family, we also detected a known pathogenic variant of retinitis pigmentosa in a healthy individual. Conclusion: c.314C>A mutation of NDP gene is a novel mutation and broadens the genetic spectrum of ND. PMID:29133643

Lasp1 misexpression influences chondrocyte differentiation in the vertebral column.

PubMed

Hermann-Kleiter, Natascha; Ghaffari-Tabrizi, Nassim; Blumer, Michael J F; Schwarzer, Christoph; Mazur, Magdalena A; Artner, Isabella

2009-01-01

The mouse mutant wavy tail Tg(Col1a1-lacZ)304ng was created through transgene insertion and exhibits defects of the vertebral column. Homozygous mutant animals have compressed tail vertebrae and wedge-shaped intervertebral discs, resulting in a meandering tail. Delayed closure of lumbar neural arches and lack of processus spinosi have been observed; these defects become most prominent during the transition from cartilage to bone. The spina bifida was resistant to folic acid treatment, while retinoic acid administration caused severe skeletal defects in the mutant, but none in wild type control animals. The transgene integrated at chromosome 11 band D, in an area of high gene density. The insertion site was located between the transcription start sites of the Rpl23 and Lasp1 genes. LASP1 (an actin binding protein involved in cell migration and survival) was found to be produced in resting and hypertrophic chondrocytes in the vertebrae. In mutant vertebrae, temporal and spatial misexpression of Lasp1 was observed, indicating that alterations in Lasp1 transcription are most likely responsible for the observed phenotype. These data reveal a yet unappreciated role of Lasp1 in chondrocyte differentiation during cartilage to bone transition.

Defining the Role of Essential Genes in Human Disease

PubMed Central

Robertson, David L.; Hentges, Kathryn E.

2011-01-01

A greater understanding of the causes of human disease can come from identifying characteristics that are specific to disease genes. However, a full understanding of the contribution of essential genes to human disease is lacking, due to the premise that these genes tend to cause developmental abnormalities rather than adult disease. We tested the hypothesis that human orthologs of mouse essential genes are associated with a variety of human diseases, rather than only those related to miscarriage and birth defects. We segregated human disease genes according to whether the knockout phenotype of their mouse ortholog was lethal or viable, defining those with orthologs producing lethal knockouts as essential disease genes. We show that the human orthologs of mouse essential genes are associated with a wide spectrum of diseases affecting diverse physiological systems. Notably, human disease genes with essential mouse orthologs are over-represented among disease genes associated with cancer, suggesting links between adult cellular abnormalities and developmental functions. The proteins encoded by essential genes are highly connected in protein-protein interaction networks, which we find correlates with an over-representation of nuclear proteins amongst essential disease genes. Disease genes associated with essential orthologs also are more likely than those with non-essential orthologs to contribute to disease through an autosomal dominant inheritance pattern, suggesting that these diseases may actually result from semi-dominant mutant alleles. Overall, we have described attributes found in disease genes according to the essentiality status of their mouse orthologs. These findings demonstrate that disease genes do occupy highly connected positions in protein-protein interaction networks, and that due to the complexity of disease-associated alleles, essential genes cannot be ignored as candidates for causing diverse human diseases. PMID:22096564

A novel AMELX mutation causes hypoplastic amelogenesis imperfecta.

PubMed

Kim, Young-Jae; Kim, Youn Jung; Kang, Jenny; Shin, Teo Jeon; Hyun, Hong-Keun; Lee, Sang-Hoon; Lee, Zang Hee; Kim, Jung-Wook

2017-04-01

Amelogenesis imperfecta (AI) is a hereditary genetic defect affecting tooth enamel. AI is heterogeneous in clinical phenotype as well as in genetic etiology. To date, more than 10 genes have been associated with the etiology of AI. Amelogenin is the most abundant enamel matrix protein, most of which is encoded by the amelogenin gene in the X-chromosome (AMELX). More than 16 alternative splicing transcripts have been identified in the murine Amelx gene. The purpose of this study was to identify the genetic cause of an AI family. We recruited a family with hypoplastic AI and performed mutational analysis on the candidate gene based on the clinical phenotype. Mutational analysis revealed a missense mutation in exon 6 (NM_182680.1; c.242C > T), which changes a sequence in a highly conserved amino acid (NP_872621.1; p.Pro81Leu). Furthermore, a splicing assay using a minigene displayed that the mutation changed the mRNA splicing repertory. In this study, we identified a novel AMELX missense mutation causing hypoplastic AI, and this mutation also resulted in altered mRNA splicing. These results will not only expand the mutation spectrum causing AI but also broaden our understanding of the biological mechanism of enamel formation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Loss-of-function mutation in Hippo suppressed enlargement of lysosomes and neurodegeneration caused by dFIG4 knockdown.

PubMed

Kushimura, Yukie; Azuma, Yumiko; Mizuta, Ikuko; Muraoka, Yuuka; Kyotani, Akane; Yoshida, Hideki; Tokuda, Takahiko; Mizuno, Toshiki; Yamaguchi, Masamitsu

2018-05-08

Charcot-Marie-Tooth disease (CMT) is the most common hereditary neuropathy, and more than 80 CMT-causing genes have been identified to date. CMT4J is caused by a loss-of-function mutation in the Factor-Induced-Gene 4 (FIG4) gene, the product of which plays important roles in endosome-lysosome homeostasis. We hypothesized that Mammalian sterile 20-like kinase (MST) 1 and 2, tumor-suppressor genes, are candidate modifiers of CMT4J. We therefore examined the interaction between dFIG4 and Hippo (hpo), Drosophila counterparts of FIG4 and MSTs, respectively, using the Drosophila CMT4J model with the knockdown of dFIG4. The loss-of-function allele of hpo improved the rough eye morphology, locomotive dysfunction accompanied by structural defects in the presynaptic terminals of motoneurons, and the enlargement of lysosomes caused by the knockdown of dFIG4. Therefore, we identified hpo as a modifier of phenotypes induced by the knockdown of dFIG4. These results in Drosophila may provide an insight into the pathogenesis of CMT4J and contribute toward the development of disease-modifying therapy for CMT. We also identified the regulation of endosome-lysosome homeostasis as a novel probable function of Hippo/MST.

Topographical cone photopigment gene expression in deutan-type red-green color vision defects.

PubMed

Bollinger, Kathryn; Sjoberg, Stacy A; Neitz, Maureen; Neitz, Jay

2004-01-01

Eye donors were identified who had X-chromosome photopigment gene arrays like those of living deuteranomalous men; the arrays contained two genes encoding long-wavelength sensitive (L) pigments as well as genes to encode middle-wavelength sensitive (M) photopigment. Ultrasensitive methods failed to detect the presence of M photopigment mRNA in the retinas of these deutan donors. This provides direct evidence that deuteranomaly is caused by the complete absence of M pigment mRNA. Additionally, for those eyes with mRNA corresponding to two different L-type photopigments, the ratio of mRNA from the first vs. downstream L genes was analyzed across the retinal topography. Results show that the pattern of first relative to downstream L gene expression in the deuteranomalous retina is similar to the pattern of L vs. M gene expression found in normal retinas.

[Spontaneous models of human diseases in dogs: ichthyoses as an example].

PubMed

André, Catherine; Grall, Anaïs; Guaguere, Éric; Thomas, Anne; Galibert, Francis

2013-06-01

Ichthyoses encompass a heterogeneous group of genodermatoses characterized by abnormal desquamation over the entire body due to defects of the terminal differentiation of keratinocytes and desquamation, which occur in the upper layer of the epidermis. Even though in humans more than 40 genes have already been identified, the genetic causes of several forms remain unknown and are difficult to identify in Humans. Strikingly, several purebred dogs are also affected by specific forms of ichthyoses. In the Golden retriever dog breed, an autosomal recessive form of ichthyosis, resembling human autosomal recessive congenital ichthyoses, has recently been diagnosed with a high incidence. We first characterized the disease occurring in the golden retriever breed and collected cases and controls. A genome-wide association study on 40 unrelated Golden retriever dogs, using the canine 49.000 SNPs (single nucleotide polymorphisms) array (Affymetrix v2), followed by statistical analyses and candidate gene sequencing, allowed to identify the causal mutation in the lipase coding PNPLA1 gene (patatin-like phospholipase domain-containing protein). Screening for alterations in the human ortholog gene in 10 autosomal recessive congenital ichthyoses families, for which no genetic cause has been identified thus far, allowed to identify two recessive mutations in the PNPLA1 protein in two families. This collaborative work between "human" and "canine" geneticists, practicians, histopathologists, biochemists and electron microscopy experts not only allowed to identify, in humans, an eighth gene for autosomal recessive congenital ichthyoses, but also allowed to highlight the function of this as-yet-unknown skin specific lipase in the lipid metabolism of the skin barrier. For veterinary medicine and breeding practices, a genetic test has been developed. These findings illustrate the importance of the discovery of relevant human orthologous canine genetic diseases, whose causes can be tracked in dog breeds more easily than in humans. Indeed, due to the selection and breeding practices applied to purebred dogs, the dog constitutes a unique species for unravelling phenotype/genotype relationships and providing new insights into human genetic diseases. This work paves the way for the identification of rare gene variants in humans that may be responsible for other keratinisation and epidermal barrier defects.

Analysis of MSH3 in endometrial cancers with defective DNA mismatch repair.

PubMed

Swisher, E M; Mutch, D G; Herzog, T J; Rader, J S; Kowalski, L D; Elbendary, A; Goodfellow, P J

1998-01-01

To clarify the origin of defective mismatch repair (MMR) in sporadic endometrial cancers with microsatellite instability (MSI), a thorough mutation analysis was performed on the human mismatch repair gene MSH3. Twenty-eight MSI-positive endometrial cancers were investigated for mutations in the human mismatch repair gene MSH3 using single-strand conformation variant (SSCV) analysis of all 24 exons. All variants were sequenced. Loss of heterozygosity was investigated at all MSH3 polymorphisms discovered. A subset of tumors were investigated for methylation of the 5' promoter region of MSH3 using Southern blot hybridization. An identical single-base deletion (delta A) predicted to result in a truncated proteins was discovered in six tumors (21.4%). This deletion occurs in a string of eight consecutive adenosine residues (A8). Because simple repeat sequences are unstable in cells with defective MMR, the observed mutation may be an effect, rather than a cause, of MSI. Evidence of inactivation of the second MSH3 allele in tumors with the delta A mutation would strongly support a causal role for these MSH3 mutations. However, there was no evidence of a second mutation, loss of sequences, or methylation of the promoter region in any of the tumors with the delta A mutation. Although the delta A mutation is a frequent event in sporadic MSI-positive endometrial cancers, it may not be causally associated with defective DNA MMR.

Unraveling the Pathogenesis of Hoyeraal-Hreidarsson Syndrome, a Complex Telomere Biology Disorder

PubMed Central

Glousker, Galina; Touzot, Fabien; Revy, Patrick; Tzfati, Yehuda; Savage, Sharon A.

2015-01-01

SUMMARY Hoyeraal-Hreidarsson (HH) syndrome is a multisystem genetic disorder characterized by very short telomeres and considered a clinically severe variant of dyskeratosis congenita (DC). The main cause of mortality, usually in early childhood, is bone marrow failure. Mutations in several telomere biology genes have been reported to cause HH in about 60% of the HH patients, but the genetic defects in the rest of the patients are still unknown. Understanding the aetiology of HH and its diverse manifestations is challenging because of the complexity of telomere biology and the multiple telomeric and non-telomeric functions played by telomere-associated proteins in processes such as telomere replication, telomere protection, DNA damage response and ribosome and spliceosome assembly. Here we review the known clinical complications, molecular defects and germline mutations associated with HH, and elucidate possible mechanistic explanations and remaining questions in our understanding of the disease. PMID:25940403

Human RTEL1 deficiency causes Hoyeraal-Hreidarsson syndrome with short telomeres and genome instability.

PubMed

Le Guen, Tangui; Jullien, Laurent; Touzot, Fabien; Schertzer, Michael; Gaillard, Laetitia; Perderiset, Mylène; Carpentier, Wassila; Nitschke, Patrick; Picard, Capucine; Couillault, Gérard; Soulier, Jean; Fischer, Alain; Callebaut, Isabelle; Jabado, Nada; Londono-Vallejo, Arturo; de Villartay, Jean-Pierre; Revy, Patrick

2013-08-15

Hoyeraal-Hreidarsson syndrome (HHS), a severe variant of dyskeratosis congenita (DC), is characterized by early onset bone marrow failure, immunodeficiency and developmental defects. Several factors involved in telomere length maintenance and/or protection are defective in HHS/DC, underlining the relationship between telomere dysfunction and these diseases. By combining whole-genome linkage analysis and exome sequencing, we identified compound heterozygous RTEL1 (regulator of telomere elongation helicase 1) mutations in three patients with HHS from two unrelated families. RTEL1 is a DNA helicase that participates in DNA replication, DNA repair and telomere integrity. We show that, in addition to short telomeres, RTEL1-deficient cells from patients exhibit hallmarks of genome instability, including spontaneous DNA damage, anaphase bridges and telomeric aberrations. Collectively, these results identify RTEL1 as a novel HHS-causing gene and highlight its role as a genomic caretaker in humans.

Genetic Drivers of Kidney Defects in the DiGeorge Syndrome.

PubMed

Lopez-Rivera, Esther; Liu, Yangfan P; Verbitsky, Miguel; Anderson, Blair R; Capone, Valentina P; Otto, Edgar A; Yan, Zhonghai; Mitrotti, Adele; Martino, Jeremiah; Steers, Nicholas J; Fasel, David A; Vukojevic, Katarina; Deng, Rong; Racedo, Silvia E; Liu, Qingxue; Werth, Max; Westland, Rik; Vivante, Asaf; Makar, Gabriel S; Bodria, Monica; Sampson, Matthew G; Gillies, Christopher E; Vega-Warner, Virginia; Maiorana, Mariarosa; Petrey, Donald S; Honig, Barry; Lozanovski, Vladimir J; Salomon, Rémi; Heidet, Laurence; Carpentier, Wassila; Gaillard, Dominique; Carrea, Alba; Gesualdo, Loreto; Cusi, Daniele; Izzi, Claudia; Scolari, Francesco; van Wijk, Joanna A E; Arapovic, Adela; Saraga-Babic, Mirna; Saraga, Marijan; Kunac, Nenad; Samii, Ali; McDonald-McGinn, Donna M; Crowley, Terrence B; Zackai, Elaine H; Drozdz, Dorota; Miklaszewska, Monika; Tkaczyk, Marcin; Sikora, Przemyslaw; Szczepanska, Maria; Mizerska-Wasiak, Malgorzata; Krzemien, Grazyna; Szmigielska, Agnieszka; Zaniew, Marcin; Darlow, John M; Puri, Prem; Barton, David; Casolari, Emilio; Furth, Susan L; Warady, Bradley A; Gucev, Zoran; Hakonarson, Hakon; Flogelova, Hana; Tasic, Velibor; Latos-Bielenska, Anna; Materna-Kiryluk, Anna; Allegri, Landino; Wong, Craig S; Drummond, Iain A; D'Agati, Vivette; Imamoto, Akira; Barasch, Jonathan M; Hildebrandt, Friedhelm; Kiryluk, Krzysztof; Lifton, Richard P; Morrow, Bernice E; Jeanpierre, Cecile; Papaioannou, Virginia E; Ghiggeri, Gian Marco; Gharavi, Ali G; Katsanis, Nicholas; Sanna-Cherchi, Simone

2017-02-23

The DiGeorge syndrome, the most common of the microdeletion syndromes, affects multiple organs, including the heart, the nervous system, and the kidney. It is caused by deletions on chromosome 22q11.2; the genetic driver of the kidney defects is unknown. We conducted a genomewide search for structural variants in two cohorts: 2080 patients with congenital kidney and urinary tract anomalies and 22,094 controls. We performed exome and targeted resequencing in samples obtained from 586 additional patients with congenital kidney anomalies. We also carried out functional studies using zebrafish and mice. We identified heterozygous deletions of 22q11.2 in 1.1% of the patients with congenital kidney anomalies and in 0.01% of population controls (odds ratio, 81.5; P=4.5×10 -14 ). We localized the main drivers of renal disease in the DiGeorge syndrome to a 370-kb region containing nine genes. In zebrafish embryos, an induced loss of function in snap29, aifm3, and crkl resulted in renal defects; the loss of crkl alone was sufficient to induce defects. Five of 586 patients with congenital urinary anomalies had newly identified, heterozygous protein-altering variants, including a premature termination codon, in CRKL. The inactivation of Crkl in the mouse model induced developmental defects similar to those observed in patients with congenital urinary anomalies. We identified a recurrent 370-kb deletion at the 22q11.2 locus as a driver of kidney defects in the DiGeorge syndrome and in sporadic congenital kidney and urinary tract anomalies. Of the nine genes at this locus, SNAP29, AIFM3, and CRKL appear to be critical to the phenotype, with haploinsufficiency of CRKL emerging as the main genetic driver. (Funded by the National Institutes of Health and others.).

The genetic architecture of microphthalmia, anophthalmia and coloboma.

PubMed

Williamson, Kathleen A; FitzPatrick, David R

2014-08-01

Microphthalmia, anophthalmia and coloboma (MAC) are distinct phenotypes that represent a continuum of structural developmental eye defects. In severe bilateral cases (anophthalmia or severe microphthalmia) the genetic cause is now identifiable in approximately 80 percent of cases, with de novo heterozygous loss-of-function mutations in SOX2 or OTX2 being the most common. The genetic cause of other forms of MAC, in particular isolated coloboma, remains unknown in the majority of cases. This review will focus on MAC phenotypes that are associated with mutation of the genes SOX2, OTX2, PAX6, STRA6, ALDH1A3, RARB, VSX2, RAX, FOXE3, BMP4, BMP7, GDF3, GDF6, ABCB6, ATOH7, C12orf57, TENM3 (ODZ3), and VAX1. Recently reported mutation of the SALL2 and YAP1 genes are discussed in brief. Clinical and genetic features were reviewed in a total of 283 unrelated MAC cases or families that were mutation-positive from these 20 genes. Both the relative frequency of mutations in MAC cohort screens and the level of confidence in the assignment of disease-causing status were evaluated for each gene. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Rare Variant of GM2 Gangliosidosis through Activator-Protein Deficiency.

PubMed

Brackmann, Florian; Kehrer, Christiane; Kustermann, Wibke; Böhringer, Judith; Krägeloh-Mann, Ingeborg; Trollmann, Regina

2017-04-01

GM2 gangliosidosis, AB variant, is a very rare form of GM2 gangliosidosis due to a deficiency of GM2 activator protein. We report on two patients with typical clinical features suggestive of GM2 gangliosidosis, but normal results for hexosaminidase A and hexosaminidase B as well as their corresponding genes. Genetic analysis of the gene encoding the activator protein, the GM2A gene, elucidated the cause of the disease, adding a novel mutation to the spectrum of GM2 AB variant. This report points out that in typical clinical constellations with normal enzyme results, genetic diagnostic for activator protein defects should be performed. Georg Thieme Verlag KG Stuttgart · New York.

The molecular genetics of the telomere biology disorders.

PubMed

Bertuch, Alison A

2016-08-02

The importance of telomere function for human health is exemplified by a collection of Mendelian disorders referred to as the telomere biology disorders (TBDs), telomeropathies, or syndromes of telomere shortening. Collectively, the TBDs cover a spectrum of conditions from multisystem disease presenting in infancy to isolated disease presentations in adulthood, most notably idiopathic pulmonary fibrosis. Eleven genes have been found mutated in the TBDs to date, each of which is linked to some aspect of telomere maintenance. This review summarizes the molecular defects that result from mutations in these genes, highlighting recent advances, including the addition of PARN to the TBD gene family and the discovery of heterozygous mutations in RTEL1 as a cause of familial pulmonary fibrosis.

Molecular genetics in neurology.

PubMed

Martin, J B

1993-12-01

There has been remarkable progress in the identification of mutations in genes that cause inherited neurological disorders. Abnormalities in the genes for Huntington disease, neurofibromatosis types 1 and 2, one form of familial amyotrophic lateral sclerosis, fragile X syndrome, myotonic dystrophy, Kennedy syndrome, Menkes disease, and several forms of retinitis pigmentosa have been elucidated. Rare disorders of neuronal migration such as Kallmann syndrome, Miller-Dieker syndrome, and Norrie disease have been shown to be due to specific gene defects. Several muscle disorders characterized by abnormal membrane excitability have been defined as mutations of the muscle sodium or chloride channels. These advances provide opportunity for accurate molecular diagnosis of at-risk individuals and are the harbinger of new approaches to therapy of these diseases.

Molecular genetic analysis of consanguineous Pakistani families with autosomal recessive hypohidrotic ectodermal dysplasia.

PubMed

Bibi, Nosheen; Ahmad, Saeed; Ahmad, Wasim; Naeem, Muhammad

2011-02-01

Hypohidrotic ectodermal dysplasia is an inherited disorder characterized by defective development of teeth, hairs and sweat glands. X-linked hypohidrotic ectodermal dysplasia is caused by mutations in the EDA gene, and autosomal forms of hypohidrotic ectodermal dysplasia are caused by mutations in either the EDAR or the EDARADD genes. To study the molecular genetic cause of autosomal recessive hypohidrotic ectodermal dysplasia in three consanguineous Pakistani families (A, B and C), genotyping of 13 individuals was carried out by using polymorphic microsatellite markers that are closely linked to the EDAR gene on chromosome 2q11-q13 and the EDARADD gene on chromosome 1q42.2-q43. The results revealed linkage in the three families to the EDAR locus. Sequence analysis of the coding exons and splice junctions of the EDAR gene revealed two mutations: a novel non-sense mutation (p.E124X) in the probands of families A and B and a missense mutation (p.G382S) in the proband of family C. In addition, two synonymous single-nucleotide polymorphisms were also identified. The finding of mutations in Pakistani families extends the body of evidence that supports the importance of EDAR for the development of hypohidrotic ectodermal dysplasia. © 2010 The Authors. Australasian Journal of Dermatology © 2010 The Australasian College of Dermatologists.

[From gene to disease; primary hyperoxaluria type I caused by mutations in the AGXT gene].

PubMed

van Woerden, C S; Groothof, J W; Wanders, R J A; Waterham, H R; Wijburg, F R

2006-07-29

Primary hyperoxaluria type I (PH1) is a congenital defect in glyoxylate metabolism caused by a deficiency in the liver-specific peroxisomal enzyme known as alanine glyoxylate aminotransferase (AGT). The deficiency is due to mutations in the AGXT gene, located on chromosome 2q37.3, and results in the conversion of glyoxylate to oxalate. The crystallisation of oxalate with calcium results in symptoms varying from a solitary kidney stone to end-stage renal disease with systemic oxalosis. The diagnosis is based on increased oxalate and glycolate excretion in the urine, reduced AGT activity in liver tissue, and confirmed mutations in the AGXT gene. Over 50 disease-causing mutations have been identified in PH1, which are associated with a wide range of effects on the AGT enzyme. Homozygous Gly170Arg or Phei52Ile mutations are associated with a reduction in urinary oxalate excretion upon pyridoxine administration and long-term preservation of renal function when treatment is initiated in a timely manner. Homozygous 33insC and Gly82Arg mutations result in a much poorer prognosis. Mutational analysis of the AGXT gene in PH1 patients can be a useful tool for establishing the diagnosis and choosing an appropriate therapeutic strategy.

Mitochondrial DNA disease—molecular insights and potential routes to a cure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Oliver; Turnbull, Doug, E-mail: doug.turnbull@newcastle.ac.uk

2014-07-01

Mitochondrial DNA diseases are common neurological conditions caused by mutations in the mitochondrial genome or nuclear genes responsible for its maintenance. Current treatments for these disorders are focussed on the management of the symptoms, rather than the correction of biochemical defects caused by the mutation. This review focuses on the molecular effects of mutations, the symptoms they cause and current work focusing on the development of targeted treatments for mitochondrial DNA disease. - Highlights: • We discuss several common disease causing mtDNA mutations. • We highlight recent work linking pathogenicity to deletion size and heteroplasmy. • We discuss recent advancesmore » in the development of targeted mtDNA disease treatments.« less

Gene therapy in liver diseases: state-of-the-art and future perspectives.

PubMed

Domvri, Kalliopi; Zarogoulidis, Paul; Porpodis, Konstantinos; Koffa, Maria; Lambropoulou, Maria; Kakolyris, Stylianos; Kolios, George; Zarogoulidis, Konstantinos; Chatzaki, Ekaterini

2012-12-01

Gene therapy is a fundamentally novel therapeutic approach that involves introducing genetic material into target cells in order to fight or prevent disease. A number of different strategies of gene therapy are tested at experimental and clinical levels, including: a) replacing a mutated gene that causes disease with a healthy copy of the gene, b) inactivating a mutated gene that its improper function causes pathogenesis, c) introducing a new gene coding a therapeutic compound to fight a disease, d) introducing to the target organ an enzyme converting an inactive pro-drug to its cytotoxic metabolite. In gene therapy, the transcriptional machinery of the patient is used to produce the active factor that exerts the intended therapeutic effect, ideally in a permanent, tissue-specific and manageable way. The liver is a major target for gene therapy, presenting inherited metabolic defects of single-gene etiology, but also severe multifactorial pathologies with limited therapeutic options such as hepatocellular carcinoma. The initial promising results from gene therapy strategies in liver diseases were followed by skepticism on the actual clinical value due to specificity, efficacy, toxicity and immune limitations, but are recently re-evaluated due to progress in vector technology and monitoring techniques. The significant amount of experimental data along with the available information from clinical trials are systematically reviewed here and presented per pathological entity. Finally, future perspectives of gene therapy protocols in hepatology are summarized.

Viral repression of fungal pheromone precursor gene expression.

PubMed

Zhang, L; Baasiri, R A; Van Alfen, N K

1998-02-01

Biological control of chestnut blight caused by the filamentous ascomycete Cryphonectria parasitica can be achieved with a virus that infects this fungus. This hypovirus causes a perturbation of fungal development that results in low virulence (hypovirulence), poor asexual sporulation, and female infertility without affecting fungal growth in culture. At the molecular level, the virus is known to affect the transcription of a number of fungal genes. Two of these genes, Vir1 and Vir2, produce abundant transcripts in noninfected strains of the fungus, but the transcripts are not detectable in virus-infected strains. We report here that these two genes encode the pheromone precursors of the Mat-2 mating type of the fungus; consequently, these genes have been renamed Mf2/1 and Mf2/2. To determine if the virus affects the mating systems of both mating types of this fungus, the pheromone precursor gene, Mf1/1, of a Mat-1 strain was cloned and likewise was found to be repressed in virus-infected strains. The suppression of transcription of the pheromone precursor genes of this fungus could be the cause of the mating defect of infected strains of the fungus. Although published reports suggest that a G alpha(i) subunit may be involved in this regulation, our results do not support this hypothesis. The prepropheromone encoded by Mf1/1 is structurally similar to that of the prepro-p-factor of Schizosaccharomyces pombe. This is the first description of the complete set of pheromone precursor genes encoded by a filamentous ascomycete.

Loss of kindlin-1, a human homolog of the Caenorhabditis elegans actin-extracellular-matrix linker protein UNC-112, causes Kindler syndrome.

PubMed

Siegel, Dawn H; Ashton, Gabrielle H S; Penagos, Homero G; Lee, James V; Feiler, Heidi S; Wilhelmsen, Kirk C; South, Andrew P; Smith, Frances J D; Prescott, Alan R; Wessagowit, Vesarat; Oyama, Noritaka; Akiyama, Masashi; Al Aboud, Daifullah; Al Aboud, Khalid; Al Githami, Ahmad; Al Hawsawi, Khalid; Al Ismaily, Abla; Al-Suwaid, Raouf; Atherton, David J; Caputo, Ruggero; Fine, Jo-David; Frieden, Ilona J; Fuchs, Elaine; Haber, Richard M; Harada, Takashi; Kitajima, Yasuo; Mallory, Susan B; Ogawa, Hideoki; Sahin, Sedef; Shimizu, Hiroshi; Suga, Yasushi; Tadini, Gianluca; Tsuchiya, Kikuo; Wiebe, Colin B; Wojnarowska, Fenella; Zaghloul, Adel B; Hamada, Takahiro; Mallipeddi, Rajeev; Eady, Robin A J; McLean, W H Irwin; McGrath, John A; Epstein, Ervin H

2003-07-01

Kindler syndrome is an autosomal recessive disorder characterized by neonatal blistering, sun sensitivity, atrophy, abnormal pigmentation, and fragility of the skin. Linkage and homozygosity analysis in an isolated Panamanian cohort and in additional inbred families mapped the gene to 20p12.3. Loss-of-function mutations were identified in the FLJ20116 gene (renamed "KIND1" [encoding kindlin-1]). Kindlin-1 is a human homolog of the Caenorhabditis elegans protein UNC-112, a membrane-associated structural/signaling protein that has been implicated in linking the actin cytoskeleton to the extracellular matrix (ECM). Thus, Kindler syndrome is, to our knowledge, the first skin fragility disorder caused by a defect in actin-ECM linkage, rather than keratin-ECM linkage.

Multiple functions of the SNARE protein Snap29 in autophagy, endocytic, and exocytic trafficking during epithelial formation in Drosophila.

PubMed

Morelli, Elena; Ginefra, Pierpaolo; Mastrodonato, Valeria; Beznoussenko, Galina V; Rusten, Tor Erik; Bilder, David; Stenmark, Harald; Mironov, Alexandre A; Vaccari, Thomas

2014-01-01

How autophagic degradation is linked to endosomal trafficking routes is little known. Here we screened a collection of uncharacterized Drosophila mutants affecting membrane transport to identify new genes that also have a role in autophagy. We isolated a loss of function mutant in Snap29 (Synaptosomal-associated protein 29 kDa), the gene encoding the Drosophila homolog of the human protein SNAP29 and have characterized its function in vivo. Snap29 contains 2 soluble NSF attachment protein receptor (SNARE) domains and a asparagine-proline-phenylalanine (NPF motif) at its N terminus and rescue experiments indicate that both SNARE domains are required for function, whereas the NPF motif is in part dispensable. We find that Snap29 interacts with SNARE proteins, localizes to multiple trafficking organelles, and is required for protein trafficking and for proper Golgi apparatus morphology. Developing tissue lacking Snap29 displays distinctive epithelial architecture defects and accumulates large amounts of autophagosomes, highlighting a major role of Snap29 in autophagy and secretion. Mutants for autophagy genes do not display epithelial architecture or secretion defects, suggesting that the these alterations of the Snap29 mutant are unlikely to be caused by the impairment of autophagy. In contrast, we find evidence of elevated levels of hop-Stat92E (hopscotch-signal transducer and activator of transcription protein at 92E) ligand, receptor, and associated signaling, which might underlie the epithelial defects. In summary, our findings support a role of Snap29 at key steps of membrane trafficking, and predict that signaling defects may contribute to the pathogenesis of cerebral dysgenesis, neuropathy, ichthyosis, and palmoplantar keratoderma (CEDNIK), a human congenital syndrome due to loss of Snap29.

Arabidopsis HD-Zip II transcription factors control apical embryo development and meristem function.

PubMed

Turchi, Luana; Carabelli, Monica; Ruzza, Valentino; Possenti, Marco; Sassi, Massimiliano; Peñalosa, Andrés; Sessa, Giovanna; Salvi, Sergio; Forte, Valentina; Morelli, Giorgio; Ruberti, Ida

2013-05-01

The Arabidopsis genome encodes ten Homeodomain-Leucine zipper (HD-Zip) II proteins. ARABIDOPSIS THALIANA HOMEOBOX 2 (ATHB2), HOMEOBOX ARABIDOPSIS THALIANA 1 (HAT1), HAT2, HAT3 and ATHB4 are regulated by changes in the red/far red light ratio that induce shade avoidance in most of the angiosperms. Here, we show that progressive loss of HAT3, ATHB4 and ATHB2 activity causes developmental defects from embryogenesis onwards in white light. Cotyledon development and number are altered in hat3 athb4 embryos, and these defects correlate with changes in auxin distribution and response. athb2 gain-of-function mutation and ATHB2 expression driven by its promoter in hat3 athb4 result in significant attenuation of phenotypes, thus demonstrating that ATHB2 is functionally redundant to HAT3 and ATHB4. In analogy to loss-of-function mutations in HD-Zip III genes, loss of HAT3 and ATHB4 results in organ polarity defects, whereas triple hat3 athb4 athb2 mutants develop one or two radialized cotyledons and lack an active shoot apical meristem (SAM). Consistent with overlapping expression pattern of HD-Zip II and HD-Zip III gene family members, bilateral symmetry and SAM defects are enhanced when hat3 athb4 is combined with mutations in PHABULOSA (PHB), PHAVOLUTA (PHV) or REVOLUTA (REV). Finally, we show that ATHB2 is part of a complex regulatory circuit directly involving both HD-Zip II and HD-Zip III proteins. Taken together, our study provides evidence that a genetic system consisting of HD-Zip II and HD-Zip III genes cooperates in establishing bilateral symmetry and patterning along the adaxial-abaxial axis in the embryo as well as in controlling SAM activity.

Stimulation of mTORC1 with L-leucine Rescues Defects Associated with Roberts Syndrome

PubMed Central

Xu, Baoshan; Lee, Kenneth K.; Zhang, Lily; Gerton, Jennifer L.

2013-01-01

Roberts syndrome (RBS) is a human disease characterized by defects in limb and craniofacial development and growth and mental retardation. RBS is caused by mutations in ESCO2, a gene which encodes an acetyltransferase for the cohesin complex. While the essential role of the cohesin complex in chromosome segregation has been well characterized, it plays additional roles in DNA damage repair, chromosome condensation, and gene expression. The developmental phenotypes of Roberts syndrome and other cohesinopathies suggest that gene expression is impaired during embryogenesis. It was previously reported that ribosomal RNA production and protein translation were impaired in immortalized RBS cells. It was speculated that cohesin binding at the rDNA was important for nucleolar form and function. We have explored the hypothesis that reduced ribosome function contributes to RBS in zebrafish models and human cells. Two key pathways that sense cellular stress are the p53 and mTOR pathways. We report that mTOR signaling is inhibited in human RBS cells based on the reduced phosphorylation of the downstream effectors S6K1, S6 and 4EBP1, and this correlates with p53 activation. Nucleoli, the sites of ribosome production, are highly fragmented in RBS cells. We tested the effect of inhibiting p53 or stimulating mTOR in RBS cells. The rescue provided by mTOR activation was more significant, with activation rescuing both cell division and cell death. To study this cohesinopathy in a whole animal model we used ESCO2-mutant and morphant zebrafish embryos, which have developmental defects mimicking RBS. Consistent with RBS patient cells, the ESCO2 mutant embryos show p53 activation and inhibition of the TOR pathway. Stimulation of the TOR pathway with L-leucine rescued many developmental defects of ESCO2-mutant embryos. Our data support the idea that RBS can be attributed in part to defects in ribosome biogenesis, and stimulation of the TOR pathway has therapeutic potential. PMID:24098154

Stimulation of mTORC1 with L-leucine rescues defects associated with Roberts syndrome.

PubMed

Xu, Baoshan; Lee, Kenneth K; Zhang, Lily; Gerton, Jennifer L

2013-01-01

Roberts syndrome (RBS) is a human disease characterized by defects in limb and craniofacial development and growth and mental retardation. RBS is caused by mutations in ESCO2, a gene which encodes an acetyltransferase for the cohesin complex. While the essential role of the cohesin complex in chromosome segregation has been well characterized, it plays additional roles in DNA damage repair, chromosome condensation, and gene expression. The developmental phenotypes of Roberts syndrome and other cohesinopathies suggest that gene expression is impaired during embryogenesis. It was previously reported that ribosomal RNA production and protein translation were impaired in immortalized RBS cells. It was speculated that cohesin binding at the rDNA was important for nucleolar form and function. We have explored the hypothesis that reduced ribosome function contributes to RBS in zebrafish models and human cells. Two key pathways that sense cellular stress are the p53 and mTOR pathways. We report that mTOR signaling is inhibited in human RBS cells based on the reduced phosphorylation of the downstream effectors S6K1, S6 and 4EBP1, and this correlates with p53 activation. Nucleoli, the sites of ribosome production, are highly fragmented in RBS cells. We tested the effect of inhibiting p53 or stimulating mTOR in RBS cells. The rescue provided by mTOR activation was more significant, with activation rescuing both cell division and cell death. To study this cohesinopathy in a whole animal model we used ESCO2-mutant and morphant zebrafish embryos, which have developmental defects mimicking RBS. Consistent with RBS patient cells, the ESCO2 mutant embryos show p53 activation and inhibition of the TOR pathway. Stimulation of the TOR pathway with L-leucine rescued many developmental defects of ESCO2-mutant embryos. Our data support the idea that RBS can be attributed in part to defects in ribosome biogenesis, and stimulation of the TOR pathway has therapeutic potential.

Prolactin Signaling through the Short Form of Its Receptor Represses Forkhead Transcription Factor FOXO3 and Its Target Gene Galt Causing a Severe Ovarian Defect

PubMed Central

Halperin, Julia; Devi, Sangeeta Y.; Elizur, Shai; Stocco, Carlos; Shehu, Aurora; Rebourcet, Diane; Unterman, Terry G.; Leslie, Nancy D.; Le, Jamie; Binart, Nadine; Gibori, Geula

2008-01-01

Prolactin (PRL) is a hormone with over 300 biological activities. Although the signaling pathway downstream of the long form of its receptor (RL) has been well characterized, little is known about PRL actions upon activation of the short form (RS). Here, we show that mice expressing only RS exhibit an ovarian phenotype of accelerated follicular recruitment followed by massive follicular death leading to premature ovarian failure. Consequently, RS-expressing ovaries of young adults are depleted of functional follicles and formed mostly by interstitium. We also show that activation of RS represses the expression of the transcription factor Forkhead box O3 (FOXO3) and that of the enzyme galactose-1-phosphate uridyltransferase (Galt), two proteins known to be essential for normal follicular development. Our finding that FOXO3 regulates the expression of Galt and enhances its transcriptional activity indicates that it is the repression of FOXO3 by PRL acting through RS that prevents Galt expression in the ovary and causes follicular death. Coexpression of RL with RS prevents PRL inhibition of Galt, and the ovarian defect is no longer seen in RS transgenic mice that coexpress RL, suggesting that RL prevents RS-induced ovarian impairment. In summary, we show that PRL signals through RS and causes, in the absence of RL, a severe ovarian pathology by repressing the expression of FOXO3 and that of its target gene Galt. We also provide evidence of a link between the premature ovarian failure seen in mice expressing RS and in mice with FOXO3 gene deletion as well as in human with Galt mutation. PMID:17975019

A splice-site mutation affecting the paired box of PAX3 in a three generation family with Waardenburg syndrome type I (WS1).

PubMed

Attaie, A; Kim, E; Wilcox, E R; Lalwani, A K

1997-06-01

Waardenburg syndrome, an autosomal dominant disorder characterized by sensorineural hearing loss, pigmentary disturbances and other developmental defects, is the most frequent form of congenital deafness in humans. Mutations in the PAX3 gene, a transcription factor expressed during embryonic development, is associated with WS types I and III. Here we report the identification of a novel acceptor splice site mutation (86-2 A-->G) in the paired domain of the human PAX3 gene causing WS type I in a three generation family.

CLINICAL PROGRESS IN INHERITED RETINAL DEGENERATIONS: GENE THERAPY CLINICAL TRIALS AND ADVANCES IN GENETIC SEQUENCING.

PubMed

Hafler, Brian P

2017-03-01

Inherited retinal dystrophies are a significant cause of vision loss and are characterized by the loss of photoreceptors and the retinal pigment epithelium (RPE). Mutations in approximately 250 genes cause inherited retinal degenerations with a high degree of genetic heterogeneity. New techniques in next-generation sequencing are allowing the comprehensive analysis of all retinal disease genes thus changing the approach to the molecular diagnosis of inherited retinal dystrophies. This review serves to analyze clinical progress in genetic diagnostic testing and implications for retinal gene therapy. A literature search of PubMed and OMIM was conducted to relevant articles in inherited retinal dystrophies. Next-generation genetic sequencing allows the simultaneous analysis of all the approximately 250 genes that cause inherited retinal dystrophies. Reported diagnostic rates range are high and range from 51% to 57%. These new sequencing tools are highly accurate with sensitivities of 97.9% and specificities of 100%. Retinal gene therapy clinical trials are underway for multiple genes including RPE65, ABCA4, CHM, RS1, MYO7A, CNGA3, CNGB3, ND4, and MERTK for which a molecular diagnosis may be beneficial for patients. Comprehensive next-generation genetic sequencing of all retinal dystrophy genes is changing the paradigm for how retinal specialists perform genetic testing for inherited retinal degenerations. Not only are high diagnostic yields obtained, but mutations in genes with novel clinical phenotypes are also identified. In the era of retinal gene therapy clinical trials, identifying specific genetic defects will increasingly be of use to identify patients who may enroll in clinical studies and benefit from novel therapies.

Gene expression profiling of mucolipidosis type IV fibroblasts reveals deregulation of genes with relevant functions in lysosome physiology.

PubMed

Bozzato, Andrea; Barlati, Sergio; Borsani, Giuseppe

2008-04-01

Mucolipidosis type IV (MLIV, MIM 252650) is an autosomal recessive lysosomal storage disorder that causes mental and motor retardation as well as visual impairment. The lysosomal storage defect in MLIV is consistent with abnormalities of membrane traffic and organelle dynamics in the late endocytic pathway. MLIV is caused by mutations in the MCOLN1 gene, which codes for mucolipin-1 (MLN1), a member of the large family of transient receptor potential (TRP) cation channels. Although a number of studies have been performed on mucolipin-1, the pathological mechanisms underlying MLIV are not fully understood. To identify genes that characterize pathogenic changes in mucolipidosis type IV, we compared the expression profiles of three MLIV and three normal skin fibroblasts cell lines using oligonucleotide microarrays. Genes that were differentially expressed in patients' cells were identified. 231 genes were up-regulated, and 116 down-regulated. Real-Time RT-PCR performed on selected genes in six independent MLIV fibroblasts cell lines was generally consistent with the microarray findings. This study allowed to evidence the modulation at the transcriptional level of a discrete number of genes relevant in biological processes which are altered in the disease such as endosome/lysosome trafficking, lysosome biogenesis, organelle acidification and lipid metabolism.

Application of oligonucleotide array CGH to the simultaneous detection of a deletion in the nuclear TK2 gene and mtDNA depletion.

PubMed

Zhang, Shulin; Li, Fang-Yuan; Bass, Harold N; Pursley, Amber; Schmitt, Eric S; Brown, Blaire L; Brundage, Ellen K; Mardach, Rebecca; Wong, Lee-Jun

2010-01-01

Thymidine kinase 2 (TK2), encoded by the TK2 gene on chromosome 16q22, is one of the deoxyribonucleoside kinases responsible for the maintenance of mitochondrial deoxyribonucleotide pools. Defects in TK2 mainly cause a myopathic form of the mitochondrial DNA depletion syndrome (MDDS). Currently, only point mutations and small insertions and deletions have been reported in TK2 gene; gross rearrangements of TK2 gene and possible hepatic involvement in patients with TK2 mutations have not been described. We report a non-consanguineous Jordanian family with three deceased siblings due to mtDNA depletion. Sequence analysis of the father detected a heterozygous c.761T>A (p.I254N) mutation in his TK2 gene; however, point mutations in the mother were not detected. Subsequent gene dosage analysis using oligonucleotide array CGH identified an intragenic approximately 5.8-kb deletion encompassing the 5'UTR to intron 2 of her TK2 gene. Sequence analysis confirmed that the deletion spans c.1-495 to c.283-2899 of the TK2 gene (nucleotide 65,136,256-65,142,086 of chromosome 16). Analysis of liver and muscle specimens from one of the deceased infants in this family revealed compound heterozygosity for the paternal point mutation and maternal intragenic deletion. In addition, a significant reduction of the mtDNA content in liver and muscle was detected (10% and 20% of age- and tissue-matched controls, respectively). Prenatal diagnosis was performed in the third pregnancy. The fetus was found to carry both the point mutation and the deletion. This child died 6months after birth due to myopathy. A serum specimen demonstrated elevated liver transaminases in two of the infants from whom results were available. This report expands the mutation spectrum associated with TK2 deficiency. While the myopathic form of MDDS appears to be the main phenotype of TK2 mutations, liver dysfunction may also be a part of the mitochondrial depletion syndrome caused by TK2 gene defects.

Homozygosity Mapping and Candidate Prioritization Identify Mutations, Missed by Whole-Exome Sequencing, in SMOC2, Causing Major Dental Developmental Defects

PubMed Central

Bloch-Zupan, Agnès; Jamet, Xavier; Etard, Christelle; Laugel, Virginie; Muller, Jean; Geoffroy, Véronique; Strauss, Jean-Pierre; Pelletier, Valérie; Marion, Vincent; Poch, Olivier; Strahle, Uwe; Stoetzel, Corinne; Dollfus, Hélène

2011-01-01

Inherited dental malformations constitute a clinically and genetically heterogeneous group of disorders. Here, we report on a severe developmental dental defect that results in a dentin dysplasia phenotype with major microdontia, oligodontia, and shape abnormalities in a highly consanguineous family. Homozygosity mapping revealed a unique zone on 6q27-ter. The two affected children were found to carry a homozygous mutation in SMOC2. Knockdown of smoc2 in zebrafish showed pharyngeal teeth that had abnormalities reminiscent of the human phenotype. Moreover, smoc2 depletion in zebrafish affected the expression of three major odontogenesis genes: dlx2, bmp2, and pitx2. PMID:22152679

Novel mutation at the initiation codon in the Norrie disease gene in two Japanese families.

PubMed

Isashiki, Y; Ohba, N; Yanagita, T; Hokita, N; Doi, N; Nakagawa, M; Ozawa, M; Kuroda, N

1995-01-01

We have identified a new mutation of Norrie disease (ND) gene in two Japanese males from unrelated families; they showed typical ocular features of ND but no mental retardation or hearing impairment. A mutation was found in both patients at the initiation codon of exon 2 of the ND gene (ATG to GTG), with otherwise normal nucleotide sequences. Their mothers had the normal and mutant types of the gene, which was expected for heterozygotes of the disease. The mutation of the initiation codon would cause the failure of ND gene expression or a defect in translation thereby truncating the amino terminus of ND protein. In view of the rarity and marked heterogeneity of mutations in the ND gene, the present apparently unrelated Japanese families who have lived in the same area for over two centuries presumably share the origin of the mutation.

The aristaless-like homeobox protein Alx3 as an etiopathogenic factor for diabetes mellitus.

PubMed

Vallejo, Mario

2011-01-01

Inactivation of the gene encoding the aristaless-related homeodomain transcription factor Alx3 results in islet cell apoptosis and impaired glucose homeostasis that worsens with age due to the appearance of insulin resistance. Alx3-deficient mice also show extrapancreatic developmental defects with variable penetrance. These include polydactyly, craniofacial midline defects, and neural tube closure defects. In humans, related congenital defects associated with mutations in ALX3 and other aristaless-related genes are being identified. Emerging evidence suggests that normal pancreatic function in humans may require the integrity of aristaless-related genes. Here, the proposal that ALX3 could be considered as a candidate gene for the etiopathogenesis of diabetes or its complications during embryonic or fetal development is discussed.

Deletion of Lkb1 in pro-opiomelanocortin neurons impairs peripheral glucose homeostasis in mice.

PubMed

Claret, Marc; Smith, Mark A; Knauf, Claude; Al-Qassab, Hind; Woods, Angela; Heslegrave, Amanda; Piipari, Kaisa; Emmanuel, Julian J; Colom, André; Valet, Philippe; Cani, Patrice D; Begum, Ghazala; White, Anne; Mucket, Phillip; Peters, Marco; Mizuno, Keiko; Batterham, Rachel L; Giese, K Peter; Ashworth, Alan; Burcelin, Remy; Ashford, Michael L; Carling, David; Withers, Dominic J

2011-03-01

AMP-activated protein kinase (AMPK) signaling acts as a sensor of nutrients and hormones in the hypothalamus, thereby regulating whole-body energy homeostasis. Deletion of Ampkα2 in pro-opiomelanocortin (POMC) neurons causes obesity and defective neuronal glucose sensing. LKB1, the Peutz-Jeghers syndrome gene product, and Ca(2+)-calmodulin-dependent protein kinase kinase β (CaMKKβ) are key upstream activators of AMPK. This study aimed to determine their role in POMC neurons upon energy and glucose homeostasis regulation. Mice lacking either Camkkβ or Lkb1 in POMC neurons were generated, and physiological, electrophysiological, and molecular biology studies were performed. Deletion of Camkkβ in POMC neurons does not alter energy homeostasis or glucose metabolism. In contrast, female mice lacking Lkb1 in POMC neurons (PomcLkb1KO) display glucose intolerance, insulin resistance, impaired suppression of hepatic glucose production, and altered expression of hepatic metabolic genes. The underlying cellular defect in PomcLkb1KO mice involves a reduction in melanocortin tone caused by decreased α-melanocyte-stimulating hormone secretion. However, Lkb1-deficient POMC neurons showed normal glucose sensing, and body weight was unchanged in PomcLkb1KO mice. Our findings demonstrate that LKB1 in hypothalamic POMC neurons plays a key role in the central regulation of peripheral glucose metabolism but not body-weight control. This phenotype contrasts with that seen in mice lacking AMPK in POMC neurons with defects in body-weight regulation but not glucose homeostasis, which suggests that LKB1 plays additional functions distinct from activating AMPK in POMC neurons.

Copy number variation as a genetic basis for heterotaxy and heterotaxy-spectrum congenital heart defects.

PubMed

Cowan, Jason R; Tariq, Muhammad; Shaw, Chad; Rao, Mitchell; Belmont, John W; Lalani, Seema R; Smolarek, Teresa A; Ware, Stephanie M

2016-12-19

Genomic disorders and rare copy number abnormalities are identified in 15-25% of patients with syndromic conditions, but their prevalence in individuals with isolated birth defects is less clear. A spectrum of congenital heart defects (CHDs) is seen in heterotaxy, a highly heritable and genetically heterogeneous multiple congenital anomaly syndrome resulting from failure to properly establish left-right (L-R) organ asymmetry during early embryonic development. To identify novel genetic causes of heterotaxy, we analysed copy number variants (CNVs) in 225 patients with heterotaxy and heterotaxy-spectrum CHDs using array-based genotyping methods. Clinically relevant CNVs were identified in approximately 20% of patients and encompassed both known and putative heterotaxy genes. Patients were carefully phenotyped, revealing a significant association of abdominal situs inversus with pathogenic or likely pathogenic CNVs, while d-transposition of the great arteries was more frequently associated with common CNVs. Identified cytogenetic abnormalities ranged from large unbalanced translocations to smaller, kilobase-scale CNVs, including a rare, single exon deletion in ZIC3, a gene known to cause X-linked heterotaxy. Morpholino loss-of-function experiments in Xenopus support a role for one of these novel candidates, the platelet isoform of phosphofructokinase-1 (PFKP) in heterotaxy. Collectively, our results confirm a high CNV yield for array-based testing in patients with heterotaxy, and support use of CNV analysis for identification of novel biological processes relevant to human laterality.This article is part of the themed issue 'Provocative questions in left-right asymmetry'. © 2016 The Author(s).

Congenital analbuminemia caused by a novel aberrant splicing in the albumin gene.

PubMed

Caridi, Gianluca; Dagnino, Monica; Erdeve, Omer; Di Duca, Marco; Yildiz, Duran; Alan, Serdar; Atasay, Begum; Arsan, Saadet; Campagnoli, Monica; Galliano, Monica; Minchiotti, Lorenzo

2014-01-01

Congenital analbuminemia is a rare autosomal recessive disorder manifested by the presence of a very low amount of circulating serum albumin. It is an allelic heterogeneous defect, caused by variety of mutations within the albumin gene in homozygous or compound heterozygous state. Herein we report the clinical and molecular characterization of a new case of congenital analbuminemia diagnosed in a female newborn of consanguineous (first degree cousins) parents from Ankara, Turkey, who presented with a low albumin concentration (< 8 g/L) and severe clinical symptoms. The albumin gene of the index case was screened by single-strand conformation polymorphism, heteroduplex analysis, and direct DNA sequencing. The effect of the splicing mutation was evaluated by examining the cDNA obtained by reverse transcriptase - polymerase chain reaction (RT-PCR) from the albumin mRNA extracted from proband's leukocytes. DNA sequencing revealed that the proband is homozygous, and both parents are heterozygous, for a novel G>A transition at position c.1652+1, the first base of intron 12, which inactivates the strongly conserved GT dinucleotide at the 5' splice site consensus sequence of this intron. The splicing defect results in the complete skipping of the preceding exon (exon 12) and in a frame-shift within exon 13 with a premature stop codon after the translation of three mutant amino acid residues. Our results confirm the clinical diagnosis of congenital analbuminemia in the proband and the inheritance of the trait and contribute to shed light on the molecular genetics of analbuminemia.

Pivotal Advance: Eosinophilia in the MES rat strain is caused by a loss-of-function mutation in the gene for cytochrome b(-245), alpha polypeptide (Cyba).

PubMed

Mori, Masayuki; Li, Guixin; Hashimoto, Maiko; Nishio, Ayako; Tomozawa, Hiroshi; Suzuki, Nobuyoshi; Usami, Shin-ichi; Higuchi, Keiichi; Matsumoto, Kiyoshi

2009-09-01

MES is a rat strain that spontaneously develops severe blood eosinophilia as a hereditary trait. Herein, we report that eosinophilia in MES rats is caused by a loss-of-function mutation in the gene for cytochrome b(-245), alpha polypeptide (Cyba; also known as p22(phox)), which is an essential component of the superoxide-generating NADPH oxidase complex. The MES rat has a deletion of four nucleotides, including the 5' splice donor GpT of intron 4 of the Cyba gene. As a consequence of the deletion, a 51-nucleotide sequence of intron 4 is incorporated into the Cyba transcripts. Leukocytes from the MES strain lack both CYBA protein and NADPH oxidase activity. Nevertheless, unlike patients with chronic granulomatous disease, who suffer from infections with pathogens due to similar genetic defects in NADPH oxidase, MES rats retain normal innate immune defense against Staphylococcus aureus infection. This is due to large quantities of peritoneal eosinophils in MES rats, which phagocytose and kill the bacteria. MES rat has a balance defect due to impaired formation of otoconia in the utricles and saccules. Eosinophilia of the MES rat was normalized by introduction of a normal Cyba transgene. The mechanisms by which impairment of NADPH oxidase leads to eosinophilia in the MES rat are elusive. However, our study highlights the essential role of NADPH oxidase in homeostatic regulation of innate immunity beyond conventional microbicidial functions.

Achromobacter denitrificans Strain YD35 Pyruvate Dehydrogenase Controls NADH Production To Allow Tolerance to Extremely High Nitrite Levels

PubMed Central

Doi, Yuki; Shimizu, Motoyuki; Fujita, Tomoya; Nakamura, Akira; Takizawa, Noboru

2014-01-01

We identified the extremely nitrite-tolerant bacterium Achromobacter denitrificans YD35 that can grow in complex medium containing 100 mM nitrite (NO2−) under aerobic conditions. Nitrite induced global proteomic changes and upregulated tricarboxylate (TCA) cycle enzymes as well as antioxidant proteins in YD35. Transposon mutagenesis generated NO2−-hypersensitive mutants of YD35 that had mutations at genes for aconitate hydratase and α-ketoglutarate dehydrogenase in the TCA cycle and a pyruvate dehydrogenase (Pdh) E1 component, indicating the importance of TCA cycle metabolism to NO2− tolerance. A mutant in which the pdh gene cluster was disrupted (Δpdh mutant) could not grow in the presence of 100 mM NO2−. Nitrite decreased the cellular NADH/NAD+ ratio and the cellular ATP level. These defects were more severe in the Δpdh mutant, indicating that Pdh contributes to upregulating cellular NADH and ATP and NO2−-tolerant growth. Exogenous acetate, which generates acetyl coenzyme A and then is metabolized by the TCA cycle, compensated for these defects caused by disruption of the pdh gene cluster and those caused by NO2−. These findings demonstrate a link between NO2− tolerance and pyruvate/acetate metabolism through the TCA cycle. The TCA cycle mechanism in YD35 enhances NADH production, and we consider that this contributes to a novel NO2−-tolerating mechanism in this strain. PMID:24413603

Birth Defects

MedlinePlus

... both. Some birth defects like cleft lip or neural tube defects are structural problems that can be ... during pregnancy is a key factor in causing neural tube defects. For most birth defects, the cause ...

Wing Defects in Drosophila xenicid Mutant Clones Are Caused by C-Terminal Deletion of Additional Sex Combs (Asx)

PubMed Central

Bischoff, Kara; Ballew, Anna C.; Simon, Michael A.; O'Reilly, Alana M.

2009-01-01

Background The coordinated action of genes that control patterning, cell fate determination, cell size, and cell adhesion is required for proper wing formation in Drosophila. Defects in any of these basic processes can lead to wing aberrations, including blisters. The xenicid mutation was originally identified in a screen designed to uncover regulators of adhesion between wing surfaces [1]. Principal Findings Here, we demonstrate that expression of the βPS integrin or the patterning protein Engrailed are not affected in developing wing imaginal discs in xenicid mutants. Instead, expression of the homeotic protein Ultrabithorax (Ubx) is strongly increased in xenicid mutant cells. Conclusion Our results suggest that upregulation of Ubx transforms cells from a wing blade fate to a haltere fate, and that the presence of haltere cells within the wing blade is the primary defect leading to the adult wing phenotypes observed. PMID:19956620

Morphogenetic Pathway of Spore Wall Assembly in Saccharomyces cerevisiae

PubMed Central

Coluccio, Alison; Bogengruber, Edith; Conrad, Michael N.; Dresser, Michael E.; Briza, Peter; Neiman, Aaron M.

2004-01-01

The Saccharomyces cerevisiae spore is protected from environmental damage by a multilaminar extracellular matrix, the spore wall, which is assembled de novo during spore formation. A set of mutants defective in spore wall assembly were identified in a screen for mutations causing sensitivity of spores to ether vapor. The spore wall defects in 10 of these mutants have been characterized in a variety of cytological and biochemical assays. Many of the individual mutants are defective in the assembly of specific layers within the spore wall, leading to arrests at discrete stages of assembly. The localization of several of these gene products has been determined and distinguishes between proteins that likely are involved directly in spore wall assembly and probable regulatory proteins. The results demonstrate that spore wall construction involves a series of dependent steps and provide the outline of a morphogenetic pathway for assembly of a complex extracellular structure. PMID:15590821

Production and characterization of vaccines based on flaviviruses defective in replication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mason, Peter W.; Department of Pathology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1019; Sealy Center for Vaccine Development, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1019

2006-08-01

To develop new vaccine candidates for flavivirus infections, we have engineered two flaviviruses, yellow fever virus (YFV) and West Nile virus (WNV), that are deficient in replication. These defective pseudoinfectious viruses (PIVs) lack a functional copy of the capsid (C) gene in their genomes and are incapable of causing spreading infection upon infection of cells both in vivo and in vitro. However, they produce extracellular E protein in form of secreted subviral particles (SVPs) that are known to be an effective immunogen. PIVs can be efficiently propagated in trans-complementing cell lines making high levels of C or all three viralmore » structural proteins. PIVs derived from YFV and WNV, demonstrated very high safety and immunization produced high levels of neutralizing antibodies and protective immune response. Such defective flaviviruses can be produced in large scale under low biocontainment conditions and should be useful for diagnostic or vaccine applications.« less

Deletions involving long-range conserved nongenic sequences upstream and downstream of FOXL2 as a novel disease-causing mechanism in blepharophimosis syndrome.

PubMed

Beysen, D; Raes, J; Leroy, B P; Lucassen, A; Yates, J R W; Clayton-Smith, J; Ilyina, H; Brooks, S Sklower; Christin-Maitre, S; Fellous, M; Fryns, J P; Kim, J R; Lapunzina, P; Lemyre, E; Meire, F; Messiaen, L M; Oley, C; Splitt, M; Thomson, J; Van de Peer, Y; Veitia, R A; De Paepe, A; De Baere, E

2005-08-01

The expression of a gene requires not only a normal coding sequence but also intact regulatory regions, which can be located at large distances from the target genes, as demonstrated for an increasing number of developmental genes. In previous mutation studies of the role of FOXL2 in blepharophimosis syndrome (BPES), we identified intragenic mutations in 70% of our patients. Three translocation breakpoints upstream of FOXL2 in patients with BPES suggested a position effect. Here, we identified novel microdeletions outside of FOXL2 in cases of sporadic and familial BPES. Specifically, four rearrangements, with an overlap of 126 kb, are located 230 kb upstream of FOXL2, telomeric to the reported translocation breakpoints. Moreover, the shortest region of deletion overlap (SRO) contains several conserved nongenic sequences (CNGs) harboring putative transcription-factor binding sites and representing potential long-range cis-regulatory elements. Interestingly, the human region orthologous to the 12-kb sequence deleted in the polled intersex syndrome in goat, which is an animal model for BPES, is contained in this SRO, providing evidence of human-goat conservation of FOXL2 expression and of the mutational mechanism. Surprisingly, in a fifth family with BPES, one rearrangement was found downstream of FOXL2. In addition, we report nine novel rearrangements encompassing FOXL2 that range from partial gene deletions to submicroscopic deletions. Overall, genomic rearrangements encompassing or outside of FOXL2 account for 16% of all molecular defects found in our families with BPES. In summary, this is the first report of extragenic deletions in BPES, providing further evidence of potential long-range cis-regulatory elements regulating FOXL2 expression. It contributes to the enlarging group of developmental diseases caused by defective distant regulation of gene expression. Finally, we demonstrate that CNGs are candidate regions for genomic rearrangements in developmental genes.

Deletions Involving Long-Range Conserved Nongenic Sequences Upstream and Downstream of FOXL2 as a Novel Disease-Causing Mechanism in Blepharophimosis Syndrome

PubMed Central

Beysen, D.; Raes, J.; Leroy, B. P.; Lucassen, A.; Yates, J. R. W.; Clayton-Smith, J.; Ilyina, H.; Brooks, S. Sklower; Christin-Maitre, S.; Fellous, M.; Fryns, J. P.; Kim, J. R.; Lapunzina, P.; Lemyre, E.; Meire, F.; Messiaen, L. M.; Oley, C.; Splitt, M.; Thomson, J.; Peer, Y. Van de; Veitia, R. A.; De Paepe, A.; De Baere, E.

2005-01-01

The expression of a gene requires not only a normal coding sequence but also intact regulatory regions, which can be located at large distances from the target genes, as demonstrated for an increasing number of developmental genes. In previous mutation studies of the role of FOXL2 in blepharophimosis syndrome (BPES), we identified intragenic mutations in 70% of our patients. Three translocation breakpoints upstream of FOXL2 in patients with BPES suggested a position effect. Here, we identified novel microdeletions outside of FOXL2 in cases of sporadic and familial BPES. Specifically, four rearrangements, with an overlap of 126 kb, are located 230 kb upstream of FOXL2, telomeric to the reported translocation breakpoints. Moreover, the shortest region of deletion overlap (SRO) contains several conserved nongenic sequences (CNGs) harboring putative transcription-factor binding sites and representing potential long-range cis-regulatory elements. Interestingly, the human region orthologous to the 12-kb sequence deleted in the polled intersex syndrome in goat, which is an animal model for BPES, is contained in this SRO, providing evidence of human-goat conservation of FOXL2 expression and of the mutational mechanism. Surprisingly, in a fifth family with BPES, one rearrangement was found downstream of FOXL2. In addition, we report nine novel rearrangements encompassing FOXL2 that range from partial gene deletions to submicroscopic deletions. Overall, genomic rearrangements encompassing or outside of FOXL2 account for 16% of all molecular defects found in our families with BPES. In summary, this is the first report of extragenic deletions in BPES, providing further evidence of potential long-range cis-regulatory elements regulating FOXL2 expression. It contributes to the enlarging group of developmental diseases caused by defective distant regulation of gene expression. Finally, we demonstrate that CNGs are candidate regions for genomic rearrangements in developmental genes. PMID:15962237

Fused pulmonary lobes is a rat model of human Fraser syndrome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kiyozumi, Daiji; Nakano, Itsuko; Takahashi, Ken L.

Highlights: {yields} Fused pulmonary lobes (fpl) mutant rats exhibit similar phenotypes to Fraser syndrome. {yields} The fpl gene harbors a nonsense mutation in Fraser syndrome-associated gene Frem2. {yields} Fpl mutant is defined as a first model of human Fraser syndrome in rats. -- Abstract: Fused pulmonary lobes (fpl) is a mutant gene that is inherited in an autosomal recessive manner and causes various developmental defects, including fusion of pulmonary lobes, and eyelid and digit anomalies in rats. Since these developmental defects closely resemble those observed in patients with Fraser syndrome, a recessive multiorgan disorder, and its model animals, we investigatedmore » whether the abnormal phenotypes observed in fpl/fpl mutant rats are attributable to a genetic disorder similar to Fraser syndrome. At the epidermal basement membrane in fpl/fpl mutant neonates, the expression of QBRICK, a basement membrane protein whose expression is attenuated in Fraser syndrome model mice, was greatly diminished compared with control littermates. Quantitative RT-PCR analyses of Fraser syndrome-related genes revealed that Frem2 transcripts were markedly diminished in QBRICK-negative embryos. Genomic DNA sequencing of the fpl/fpl mutant identified a nonsense mutation that introduced a stop codon at serine 2005 in Frem2. These findings indicate that the fpl mutant is a rat model of human Fraser syndrome.« less

Abnormal cerebellar development and ataxia in CARP VIII morphant zebrafish.

PubMed

Aspatwar, Ashok; Tolvanen, Martti E E; Jokitalo, Eija; Parikka, Mataleena; Ortutay, Csaba; Harjula, Sanna-Kaisa E; Rämet, Mika; Vihinen, Mauno; Parkkila, Seppo

2013-02-01

Congenital ataxia and mental retardation are mainly caused by variations in the genes that affect brain development. Recent reports have shown that mutations in the CA8 gene are associated with mental retardation and ataxia in humans and ataxia in mice. The gene product, carbonic anhydrase-related protein VIII (CARP VIII), is predominantly present in cerebellar Purkinje cells, where it interacts with the inositol 1,4,5-trisphosphate receptor type 1, a calcium channel. In this study, we investigated the effects of the loss of function of CARP VIII during embryonic development in zebrafish using antisense morpholino oligonucleotides against the CA8 gene. Knockdown of CA8 in zebrafish larvae resulted in a curved body axis, pericardial edema and abnormal movement patterns. Histologic examination revealed gross morphologic defects in the cerebellar region and in the muscle. Electron microscopy studies showed increased neuronal cell death in developing larvae injected with CA8 antisense morpholinos. These data suggest a pivotal role for CARP VIII during embryonic development. Furthermore, suppression of CA8 expression leads to defects in motor and coordination functions, mimicking the ataxic human phenotype. This work reveals an evolutionarily conserved function of CARP VIII in brain development and introduces a novel zebrafish model in which to investigate the mechanisms of CARP VIII-related ataxia and mental retardation in humans.

Mutation in the pssA gene involved in exopolysaccharide synthesis leads to several physiological and symbiotic defects in Rhizobium leguminosarum bv. trifolii.

PubMed

Janczarek, Monika; Rachwał, Kamila

2013-12-05

The symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum bv. trifolii 24.2 secretes large amounts of acidic exopolysaccharide (EPS), which plays a crucial role in establishment of effective symbiosis with clover. The biosynthesis of this heteropolymer is conducted by a multi-enzymatic complex located in the bacterial inner membrane. PssA protein, responsible for the addition of glucose-1-phosphate to a polyprenyl phosphate carrier, is involved in the first step of EPS synthesis. In this work, we characterize R. leguminosarum bv. trifolii strain Rt270 containing a mini-Tn5 transposon insertion located in the 3'-end of the pssA gene. It has been established that a mutation in this gene causes a pleiotropic effect in rhizobial cells. This is confirmed by the phenotype of the mutant strain Rt270, which exhibits several physiological and symbiotic defects such as a deficiency in EPS synthesis, decreased motility and utilization of some nutrients, decreased sensitivity to several antibiotics, an altered extracellular protein profile, and failed host plant infection. The data of this study indicate that the protein product of the pssA gene is not only involved in EPS synthesis, but also required for proper functioning of Rhizobium leguminosarum bv. trifolii cells.

Genetic modifiers of abnormal organelle biogenesis in a Drosophila model of BLOC-1 deficiency

PubMed Central

Cheli, Verónica T.; Daniels, Richard W.; Godoy, Ruth; Hoyle, Diego J.; Kandachar, Vasundhara; Starcevic, Marta; Martinez-Agosto, Julian A.; Poole, Stephen; DiAntonio, Aaron; Lloyd, Vett K.; Chang, Henry C.; Krantz, David E.; Dell'Angelica, Esteban C.

2010-01-01

Biogenesis of lysosome-related organelles complex 1 (BLOC-1) is a protein complex formed by the products of eight distinct genes. Loss-of-function mutations in two of these genes, DTNBP1 and BLOC1S3, cause Hermansky–Pudlak syndrome, a human disorder characterized by defective biogenesis of lysosome-related organelles. In addition, haplotype variants within the same two genes have been postulated to increase the risk of developing schizophrenia. However, the molecular function of BLOC-1 remains unknown. Here, we have generated a fly model of BLOC-1 deficiency. Mutant flies lacking the conserved Blos1 subunit displayed eye pigmentation defects due to abnormal pigment granules, which are lysosome-related organelles, as well as abnormal glutamatergic transmission and behavior. Epistatic analyses revealed that BLOC-1 function in pigment granule biogenesis requires the activities of BLOC-2 and a putative Rab guanine-nucleotide-exchange factor named Claret. The eye pigmentation phenotype was modified by misexpression of proteins involved in intracellular protein trafficking; in particular, the phenotype was partially ameliorated by Rab11 and strongly enhanced by the clathrin-disassembly factor, Auxilin. These observations validate Drosophila melanogaster as a powerful model for the study of BLOC-1 function and its interactions with modifier genes. PMID:20015953

XERODERMA PIGMENTOSUM, TRICHOTHIODYSTROPHY AND COCKAYNE SYNDROME: A COMPLEX GENOTYPE-PHENOTYPE RELATIONSHIP

PubMed Central

Kraemer, Kenneth H.; Patronas, Nicholas J.; Schiffmann, Raphael; Brooks, Brian P.; Tamura, Deborah; DiGiovanna, John J.

2008-01-01

Patients with the rare genetic disorders, xeroderma pigmentosum (XP), trichothiodystrophy (TTD) and Cockayne syndrome (CS) have defects in DNA nucleotide excision repair (NER). The NER pathway involves at least 28 genes. Three NER genes are also part of the basal transcription factor, TFIIH. Mutations in 11 NER genes have been associated with clinical diseases with at least 8 overlapping phenotypes. The clinical features of these patients have some similarities and but also have marked differences. NER is involved in protection against sunlight induced DNA damage. While XP patients have 1000-fold increase in susceptibility to skin cancer, TTD and CS patients have normal skin cancer risk. Several of the genes involved in NER also affect somatic growth and development. Some patients have short stature and immature sexual development. TTD patients have sulfur deficient brittle hair. Progressive sensorineural deafness is an early feature of XP and CS. Many of these clinical diseases are associated with developmental delay and progressive neurological degeneration. The main neuropathology of XP is a primary neuronal degeneration. In contrast, CS and TTD patients have reduced myelination of the brain. These complex neurological abnormalities are not related to sunlight exposure but may be caused by developmental defects as well as faulty repair of DNA damage to neuronal cells induced by oxidative metabolism or other endogenous processes. PMID:17276014

Steroid 5alpha-reductase 1 polymorphisms and testosterone/dihydrotestosterone ratio in male patients with hypospadias.

PubMed

Tria, Antje; Hiort, Olaf; Sinnecker, Gernot H G

2004-01-01

Defects in the steroid 5alpha-reductase type 2 (SRD5A2) activity cause decreased formation of dihydrotestosterone (DHT) from testosterone (T), resulting in defective masculinization of external genitalia; the T/DHT ratio is increased. We investigated 10 patients with elevated T/DHT ratios in whom mutations in the SRD5A2 and AR genes had been excluded to find out whether structural alterations of the SRD5A1 gene could contribute to their genital malformations. Single-strand conformation polymorphism analysis and direct sequencing were used to detect variations in the SRD5A1 gene of the patients and of 49 adult fertile men who served as controls. The sequence analysis of exon 3 of the SRD5A1 gene indicated an adenine-to-guanine change (ACA vs. ACG), both triplets encoding the amino acid residue threonine. The ACG sequence was detected in 57% of all subjects and was equally distributed in patients and controls. The T/DHT ratio was significantly higher in controls with the ACG variant as compared with those having the ACA variant. However, no particular sequence aberration was found in the SRD5A1 genes of either group. Mutant SRD5A1 isoenzyme does not seem to play a crucial role in the development of hypospadias. Copyright 2004 S. Karger AG, Basel

Upregulation of the Nr2f1-A830082K12Rik gene pair in murine neural crest cells results in a complex phenotype reminiscent of Waardenburg syndrome type 4

PubMed Central

Bergeron, Karl-F.; Nguyen, Chloé M. A.; Cardinal, Tatiana; Charrier, Baptiste; Silversides, David W.

2016-01-01

ABSTRACT Waardenburg syndrome is a neurocristopathy characterized by a combination of skin and hair depigmentation, and inner ear defects. In the type 4 form, these defects show comorbidity with Hirschsprung disease, a disorder marked by an absence of neural ganglia in the distal colon, triggering functional intestinal obstruction. Here, we report that the Spot mouse line – obtained through an insertional mutagenesis screen for genes involved in neural crest cell (NCC) development – is a model for Waardenburg syndrome type 4. We found that the Spot insertional mutation causes overexpression of an overlapping gene pair composed of the transcription-factor-encoding Nr2f1 and the antisense long non-coding RNA A830082K12Rik in NCCs through a mechanism involving relief of repression of these genes. Consistent with the previously described role of Nr2f1 in promoting gliogenesis in the central nervous system, we further found that NCC-derived progenitors of the enteric nervous system fail to fully colonize Spot embryonic guts owing to their premature differentiation in glial cells. Taken together, our data thus identify silencer elements of the Nr2f1-A830082K12Rik gene pair as new candidate loci for Waardenburg syndrome type 4. PMID:27585883

Upregulation of the Nr2f1-A830082K12Rik gene pair in murine neural crest cells results in a complex phenotype reminiscent of Waardenburg syndrome type 4.

PubMed

Bergeron, Karl-F; Nguyen, Chloé M A; Cardinal, Tatiana; Charrier, Baptiste; Silversides, David W; Pilon, Nicolas

2016-11-01

Waardenburg syndrome is a neurocristopathy characterized by a combination of skin and hair depigmentation, and inner ear defects. In the type 4 form, these defects show comorbidity with Hirschsprung disease, a disorder marked by an absence of neural ganglia in the distal colon, triggering functional intestinal obstruction. Here, we report that the Spot mouse line - obtained through an insertional mutagenesis screen for genes involved in neural crest cell (NCC) development - is a model for Waardenburg syndrome type 4. We found that the Spot insertional mutation causes overexpression of an overlapping gene pair composed of the transcription-factor-encoding Nr2f1 and the antisense long non-coding RNA A830082K12Rik in NCCs through a mechanism involving relief of repression of these genes. Consistent with the previously described role of Nr2f1 in promoting gliogenesis in the central nervous system, we further found that NCC-derived progenitors of the enteric nervous system fail to fully colonize Spot embryonic guts owing to their premature differentiation in glial cells. Taken together, our data thus identify silencer elements of the Nr2f1-A830082K12Rik gene pair as new candidate loci for Waardenburg syndrome type 4. © 2016. Published by The Company of Biologists Ltd.

Crosstalk between AhR and wnt/β-catenin signal pathways in the cardiac developmental toxicity of PM2.5 in zebrafish embryos.

PubMed

Zhang, Hang; Yao, Yugang; Chen, Yang; Yue, Cong; Chen, Jiahong; Tong, Jian; Jiang, Yan; Chen, Tao

2016-04-29

Recent studies have shown an association between congenital heart defects and air fine particle matter (PM2.5), but the molecular mechanisms remain elusive. It is well known that a number of organic compounds in PM2.5 can act as AhR agonists, and activation of AhR can antagonize Wnt/β-catenin signaling. Therefore, we hypothesized that PM2.5 could activate AhR and then repress the expression of wnt/β-catenin targeted genes essential for cardiogenesis, resulting in heart defects. To test this hypothesis, we investigated the effects of extractable organic matter (EOM) from PM2.5 on AhR and Wnt/β-catenin signal pathways in zebrafish embryos. We confirmed that EOM could cause malformations in the heart and decreased heart rate in zebrafish embryos at 72hpf, and found that the EOM-induced heart defects were rescued in embryos co-exposed with EOM plus AhR antagonist CH223191 or β-catenin agonist CHIR99021. We further found that EOM had increased the expression levels of AhR targeted genes (Cyp1a1, Cyp1b1 and Ahrra) and reduced the mRNA levels of β-catenin targeted genes (axin2, nkx2.5 and sox9b). The mRNA expression level of Rspo2, a β-catenin upstream gene, was also decreased in embryos exposed to EOM. Supplementation with CH223191 or CHIR99021 attenuated most of the EOM-induced expression changes of genes involved in both AhR and wnt/β-catenin signal pathways. However, the mRNA expression level of AhR inhibitor Ahrrb, which did not change by EOM treatment alone, was increased in embryos co-exposed to EOM plus CH223191 or CHIR99021. We conclude that the activation of AhR by EOM from PM2.5 might repress wnt/β-catenin signaling, leading to heart defects in zebrafish embryos. Furthermore, our results indicate that the cardiac developmental toxicity of PM2.5 might be prevented by targeting AhR or wnt/β-catenin signaling. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Mutations in GDP-mannose pyrophosphorylase B cause congenital and limb-girdle muscular dystrophies associated with hypoglycosylation of α-dystroglycan.

PubMed

Carss, Keren J; Stevens, Elizabeth; Foley, A Reghan; Cirak, Sebahattin; Riemersma, Moniek; Torelli, Silvia; Hoischen, Alexander; Willer, Tobias; van Scherpenzeel, Monique; Moore, Steven A; Messina, Sonia; Bertini, Enrico; Bönnemann, Carsten G; Abdenur, Jose E; Grosmann, Carla M; Kesari, Akanchha; Punetha, Jaya; Quinlivan, Ros; Waddell, Leigh B; Young, Helen K; Wraige, Elizabeth; Yau, Shu; Brodd, Lina; Feng, Lucy; Sewry, Caroline; MacArthur, Daniel G; North, Kathryn N; Hoffman, Eric; Stemple, Derek L; Hurles, Matthew E; van Bokhoven, Hans; Campbell, Kevin P; Lefeber, Dirk J; Lin, Yung-Yao; Muntoni, Francesco

2013-07-11

Congenital muscular dystrophies with hypoglycosylation of α-dystroglycan (α-DG) are a heterogeneous group of disorders often associated with brain and eye defects in addition to muscular dystrophy. Causative variants in 14 genes thought to be involved in the glycosylation of α-DG have been identified thus far. Allelic mutations in these genes might also cause milder limb-girdle muscular dystrophy phenotypes. Using a combination of exome and Sanger sequencing in eight unrelated individuals, we present evidence that mutations in guanosine diphosphate mannose (GDP-mannose) pyrophosphorylase B (GMPPB) can result in muscular dystrophy variants with hypoglycosylated α-DG. GMPPB catalyzes the formation of GDP-mannose from GTP and mannose-1-phosphate. GDP-mannose is required for O-mannosylation of proteins, including α-DG, and it is the substrate of cytosolic mannosyltransferases. We found reduced α-DG glycosylation in the muscle biopsies of affected individuals and in available fibroblasts. Overexpression of wild-type GMPPB in fibroblasts from an affected individual partially restored glycosylation of α-DG. Whereas wild-type GMPPB localized to the cytoplasm, five of the identified missense mutations caused formation of aggregates in the cytoplasm or near membrane protrusions. Additionally, knockdown of the GMPPB ortholog in zebrafish caused structural muscle defects with decreased motility, eye abnormalities, and reduced glycosylation of α-DG. Together, these data indicate that GMPPB mutations are responsible for congenital and limb-girdle muscular dystrophies with hypoglycosylation of α-DG. Copyright © 2013 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

DCLRE1C (ARTEMIS) mutations causing phenotypes ranging from atypical severe combined immunodeficiency to mere antibody deficiency

PubMed Central

Volk, Timo; Pannicke, Ulrich; Reisli, Ismail; Bulashevska, Alla; Ritter, Julia; Björkman, Andrea; Schäffer, Alejandro A.; Fliegauf, Manfred; Sayar, Esra H.; Salzer, Ulrich; Fisch, Paul; Pfeifer, Dietmar; Di Virgilio, Michela; Cao, Hongzhi; Yang, Fang; Zimmermann, Karin; Keles, Sevgi; Caliskaner, Zafer; Güner, S¸ükrü; Schindler, Detlev; Hammarström, Lennart; Rizzi, Marta; Hummel, Michael; Pan-Hammarström, Qiang; Schwarz, Klaus; Grimbacher, Bodo

2015-01-01

Null mutations in genes involved in V(D)J recombination cause a block in B- and T-cell development, clinically presenting as severe combined immunodeficiency (SCID). Hypomorphic mutations in the non-homologous end-joining gene DCLRE1C (encoding ARTEMIS) have been described to cause atypical SCID, Omenn syndrome, Hyper IgM syndrome and inflammatory bowel disease—all with severely impaired T-cell immunity. By whole-exome sequencing, we investigated the molecular defect in a consanguineous family with three children clinically diagnosed with antibody deficiency. We identified perfectly segregating homozygous variants in DCLRE1C in three index patients with recurrent respiratory tract infections, very low B-cell numbers and serum IgA levels. In patients, decreased colony survival after irradiation, impaired proliferative response and reduced counts of naïve T cells were observed in addition to a restricted T-cell receptor repertoire, increased palindromic nucleotides in the complementarity determining regions 3 and long stretches of microhomology at switch junctions. Defective V(D)J recombination was complemented by wild-type ARTEMIS protein in vitro. Subsequently, homozygous or compound heterozygous DCLRE1C mutations were identified in nine patients from the same geographic region. We demonstrate that DCLRE1C mutations can cause a phenotype presenting as only antibody deficiency. This novel association broadens the clinical spectrum associated with ARTEMIS mutations. Clinicians should consider the possibility that an immunodeficiency with a clinically mild initial presentation could be a combined immunodeficiency, so as to provide appropriate care for affected patients. PMID:26476407

Genotype-phenotype relationships in human red/green color-vision defects: Molecular and psychophysical studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deeb, S.S.; Motulsky, A.G.; Lindsey, D.T.

1992-10-01

The relationship between the molecular structure of the X-linked red and green visual pigment genes and color-vision phenotype as ascertained by anomaloscopy was studied in 64 color-defective males. The great majority of red-green defects were associated with either the deletion of the green-pigment gene or the formation of 5[prime] red-green hybrid genes or 5[prime] green-red hybrid genes. A rapid PCR-based method allowed detection of hybrid genes, including those undetectable by Southern blot analysis, as well as more precise localization of the fusion points in hybrid genes. Protan color-vision defects appeared always associated with 5[prime] red-green hybrid genes. Carriers of singlemore » red-green hybrid genes with fusion in introns 1-4 were protanopes. However, carriers of hybrid genes with red-green fusions in introns 2, 3, or 4 in the presence of additional normal green genes manifested as either protanopes or protanomalous trichromats, with the majority being protanomalous. Deutan defects were associated with green-pigment gene deletions, with 5[prime] green-red hybrid genes, or, rarely, with 5[prime] green-red-green hybrid genes. Complete green-pigment gene deletions or green-red fusions in intron 1 were usually associated with deuteranopia, although the authors unexpectedly found three carriers of a single red-pigment gene without any green-pigment genes to be deuteranomalous trichromats. All but one of the other deuteranomalous subjects had green-red hybrid genes with intron 1, 2, 3, or 4 fusions, as well as several normal green-pigment genes. The one exception had a grossly normal gene array, presumably with a more subtle mutation. Amino acid differences in exon 5 largely determine whether a hybrid gene will be more redlike or more greenlike in phenotype. Various discrepancies as to severity (dichromacy or trichromacy) remain unexplained but may arise because of variability of expression, postreceptoral variation, or both.« less

Dominant Mutations in S. cerevisiae PMS1 Identify the Mlh1-Pms1 Endonuclease Active Site and an Exonuclease 1-Independent Mismatch Repair Pathway

PubMed Central

Smith, Catherine E.; Mendillo, Marc L.; Bowen, Nikki; Hombauer, Hans; Campbell, Christopher S.; Desai, Arshad; Putnam, Christopher D.; Kolodner, Richard D.

2013-01-01

Lynch syndrome (hereditary nonpolypsis colorectal cancer or HNPCC) is a common cancer predisposition syndrome. Predisposition to cancer in this syndrome results from increased accumulation of mutations due to defective mismatch repair (MMR) caused by a mutation in one of the mismatch repair genes MLH1, MSH2, MSH6 or PMS2/scPMS1. To better understand the function of Mlh1-Pms1 in MMR, we used Saccharomyces cerevisiae to identify six pms1 mutations (pms1-G683E, pms1-C817R, pms1-C848S, pms1-H850R, pms1-H703A and pms1-E707A) that were weakly dominant in wild-type cells, which surprisingly caused a strong MMR defect when present on low copy plasmids in an exo1Δ mutant. Molecular modeling showed these mutations caused amino acid substitutions in the metal coordination pocket of the Pms1 endonuclease active site and biochemical studies showed that they inactivated the endonuclease activity. This model of Mlh1-Pms1 suggested that the Mlh1-FERC motif contributes to the endonuclease active site. Consistent with this, the mlh1-E767stp mutation caused both MMR and endonuclease defects similar to those caused by the dominant pms1 mutations whereas mutations affecting the predicted metal coordinating residue Mlh1-C769 had no effect. These studies establish that the Mlh1-Pms1 endonuclease is required for MMR in a previously uncharacterized Exo1-independent MMR pathway. PMID:24204293

Dominant mutations in S. cerevisiae PMS1 identify the Mlh1-Pms1 endonuclease active site and an exonuclease 1-independent mismatch repair pathway.

PubMed

Smith, Catherine E; Mendillo, Marc L; Bowen, Nikki; Hombauer, Hans; Campbell, Christopher S; Desai, Arshad; Putnam, Christopher D; Kolodner, Richard D

2013-10-01

Lynch syndrome (hereditary nonpolypsis colorectal cancer or HNPCC) is a common cancer predisposition syndrome. Predisposition to cancer in this syndrome results from increased accumulation of mutations due to defective mismatch repair (MMR) caused by a mutation in one of the mismatch repair genes MLH1, MSH2, MSH6 or PMS2/scPMS1. To better understand the function of Mlh1-Pms1 in MMR, we used Saccharomyces cerevisiae to identify six pms1 mutations (pms1-G683E, pms1-C817R, pms1-C848S, pms1-H850R, pms1-H703A and pms1-E707A) that were weakly dominant in wild-type cells, which surprisingly caused a strong MMR defect when present on low copy plasmids in an exo1Δ mutant. Molecular modeling showed these mutations caused amino acid substitutions in the metal coordination pocket of the Pms1 endonuclease active site and biochemical studies showed that they inactivated the endonuclease activity. This model of Mlh1-Pms1 suggested that the Mlh1-FERC motif contributes to the endonuclease active site. Consistent with this, the mlh1-E767stp mutation caused both MMR and endonuclease defects similar to those caused by the dominant pms1 mutations whereas mutations affecting the predicted metal coordinating residue Mlh1-C769 had no effect. These studies establish that the Mlh1-Pms1 endonuclease is required for MMR in a previously uncharacterized Exo1-independent MMR pathway.

Distal renal tubular acidosis. Clinical manifestations in patients with different underlying gene mutations.

PubMed

Alonso-Varela, Marta; Gil-Peña, Helena; Coto, Eliecer; Gómez, Juan; Rodríguez, Julián; Rodríguez-Rubio, Enrique; Santos, Fernando

2018-05-03

To evaluate whether there are differences in the phenotype of primary distal renal tubular acidosis (dRTA) patients according to the causal defective gene. Twenty-seven non-oriental patients with genetically confirmed dRTA were grouped according to the identified underlying mutations in either ATP6V1B1 (n = 10), ATP6V0A4 (n = 12), or SLC4A1 (n = 5) gene. Demographic features, growth impairment, biochemical variables and presence of deafness, nephrocalcinosis, and urolithiasis at diagnosis were compared among the three groups. Patients with SLC4A1 mutations presented later than those with ATP6V1B1 or ATP6V0A4 defects (120 vs. 7 and 3 months, respectively). Hearing loss at diagnosis was present in the majority of patients with ATP6V1B1 mutations, in two patients with ATP6V0A4 mutations, and in none of cases harboring SLC4A1 mutations. Serum potassium concentration (X ± SD) was higher in SLC4A1 group (3.66 ± 0.44 mEq/L) than in ATP6V0A4 group (2.96 ± 0.63 mEq/L) (p = 0.046). There were no differences in the other clinical or biochemical variables analyzed in the three groups. This study indicates that non-oriental patients with dRTA caused by mutations in the SLC4A1 gene present later and have normokalemia or milder hypokalemia. Hypoacusia at diagnosis is characteristically associated with ATP6V1B1 gene mutations although it may also be present in infants with ATP6V0A4 defects. Other phenotypical manifestations do not allow predicting the involved gene.

Role for the Ankyrin eukaryotic-like genes of Legionella pneumophila in parasitism of protozoan hosts and human macrophages.

PubMed

Habyarimana, Fabien; Al-Khodor, Souhaila; Kalia, Awdhesh; Graham, James E; Price, Christopher T; Garcia, Maria Teresa; Kwaik, Yousef Abu

2008-06-01

Legionella pneumophila is a ubiquitous organism in the aquatic environment where it is capable of invasion and intracellular proliferation within various protozoan species and is also capable of causing pneumonia in humans. In silico analysis showed that the three sequenced L. pneumophila genomes each contained a common multigene family of 11 ankyrin (ank) genes encoding proteins with approximately 30-35 amino acid tandem Ankyrin repeats that are involved in protein-protein interactions in eukaryotic cells. To examine whether the ank genes are involved in tropism of protozoan hosts, we have constructed isogenic mutants of L. pneumophila in ten of the ank genes. Among the mutants, the DeltaankH and DeltaankJ mutants exhibit significant defects in robust intracellular replication within A. polyphaga, Hartmanella vermiformis and Tetrahymena pyriformis. A similar defect is also exhibited in human macrophages. Most of the ank genes are upregulated by L. pneumophila upon growth transition into the post-exponential phase in vitro and within Acanthamoeba polyphaga, and this upregulation is mediated, at least in part, by RpoS. Single-cell analyses have shown that upon co-infection of the wild-type strain with the ankH or ankJ mutant, the replication defect of the mutant is rescued within communal phagosomes harbouring the wild-type strain, similar to dot/icm mutants. Therefore, at least two of the L. pneumophila eukaryotic-like Ank proteins play a role in intracellular replication of L. pneumophila within amoeba, ciliated protozoa and human macrophages. The Ank proteins may not be involved in host tropism in the aquatic environment. Many of the L. pneumophila eukaryotic-like ank genes are triggered upon growth transition into post-exponential phase in vitro as well as within A. polyphaga. Our data suggest a role for AnkH and AnkJ in modulation of phagosome biogenesis by L. pneumophila independent of evasion of lysosomal fusion and recruitment of the rough endoplasmic reticulum.

The red-green visual pigment gene region in adrenoleukodystrophy.

PubMed Central

Aubourg, P; Feil, R; Guidoux, S; Kaplan, J C; Moser, H; Kahn, A; Mandel, J L

1990-01-01

Although recent data established that a specific very-long-chain fatty acyl-CoA synthetase is defective in X-linked adrenoleukodystrophy (ALD), the ALD gene is still unidentified. The ALD locus has been mapped to Xq28, like the red and green color pigment genes. Abnormal color vision has been observed in 12 of 27 patients with adrenomyeloneuropathy (AMN), a milder form of ALD. Furthermore, rearrangements of the color vision gene cluster were found in four of eight ALD kindreds. This led us to propose that a single DNA rearrangement could underlie both ALD and abnormal color vision in these patients. Study of 34 French ALD patients failed to reveal a higher than expected frequency of green/red visual pigment rearrangements 3' to the red/green color vision gene complex. The previous report of such rearrangements was based on small numbers and lack of knowledge that the frequency of "abnormal" color vision arrays on molecular analysis was twice as high as expected on the basis of the frequency of phenotypic color vision defects. The red/green color pigment (R/GCP) region was studied by pulsed-field gel electrophoresis in 14 of these patients, and we did not find any fragment size difference between the patients and normal individuals who have the same number of pigment genes. The R/GCP region was also analyzed in 29 French and seven North American ALD patients by using six genomic DNA probes, isolated from a cosmid walk, that flank the color vision genes. No deletions were found with probes that lie 3' of the green pigment genes. One of the eight previously reported ALD individuals has a long deletion 5' of the red pigment gene, a deletion causing blue cone monochromacy. This finding and the previous findings of a 45% frequency of phenotypic color vision defects in patients with AMN may suggest that the ALD/AMN gene lies 5' to the red pigment gene and that the frequent phenotypic color vision anomalies owe their origin to deleted DNA that includes regulatory genes for color vision. It is possible, however, that phenotypic color vision anomalies in AMN may be phenocopies secondary to retinal or neural involvement by the disease. The single case of blue cone monochromacy may therefore be a fortuitous coincidence of two diseases. Images p[466]-a Figure 3 Figure 4 Figure 5 Figure 7 Figure 8 PMID:2309698

Molecular Analysis of Congenital Hypothyroidism in Saudi Arabia: SLC26A7 Mutation Is a Novel Defect in Thyroid Dyshormonogenesis.

PubMed

Zou, Minjing; Alzahrani, Ali S; Al-Odaib, Ali; Alqahtani, Mohammad A; Babiker, Omer; Al-Rijjal, Roua A; BinEssa, Huda A; Kattan, Walaa E; Al-Enezi, Anwar F; Al Qarni, Ali; Al-Faham, Manar S A; Baitei, Essa Y; Alsagheir, Afaf; Meyer, Brian F; Shi, Yufei

2018-05-01

Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder, affecting one in 3000 to 4000 newborns. Since the introduction of a newborn screening program in 1988, more than 300 cases have been identified. The underlying genetic defects have not been systematically studied. To identify the mutation spectrum of CH-causing genes. Fifty-five patients from 47 families were studied by next-generation exome sequencing. Mutations were identified in 52.7% of patients (29 of 55) in the following 11 genes: TG, TPO, DUOX2, SLC26A4, SLC26A7, TSHB, TSHR, NKX2-1, PAX8, CDCA8, and HOXB3. Among 30 patients with thyroid dyshormonogenesis, biallelic TG mutations were found in 12 patients (40%), followed by biallelic mutations in TPO (6.7%), SLC26A7 (6.7%), and DUOX2 (3.3%). Monoallelic SLC26A4 mutations were found in two patients, one of them coexisting with two tandem biallelic deletions in SLC26A7. In 25 patients with thyroid dysgenesis, biallelic mutations in TSHR were found in six patients (24%). Biallelic mutations in TSHB, PAX 8, NKX2-1, or HOXB3 were found once in four different patients. A monoallelic CDCA8 mutation was found in one patient. Most mutations were novel, including three TG, two TSHR, and one each in DUOX2, TPO, SLC26A7, TSHB, NKX2-1, PAX8, CDCA8, and HOXB3. SLC26A7 and HOXB3 were novel genes associated with thyroid dyshormonogenesis and dysgenesis, respectively. TG and TSHR mutations are the most common genetic defects in Saudi patients with CH. The prevalence of other disease-causing mutations is low, reflecting the consanguineous nature of the population. SLC26A7 mutations appear to be associated with thyroid dyshormonogenesis.

Novel mutations in RASGRP2, which encodes CalDAG-GEFI, abrogate Rap1 activation, causing platelet dysfunction

PubMed Central

Lozano, María Luisa; Cook, Aaron; Bastida, José María; Paul, David S.; Iruin, Gemma; Cid, Ana Rosa; Adan-Pedroso, Rosa; Ramón González-Porras, José; Hernández-Rivas, Jesús María; Fletcher, Sarah J.; Johnson, Ben; Morgan, Neil; Ferrer-Marin, Francisca; Vicente, Vicente; Sondek, John; Watson, Steve P.; Bergmeier, Wolfgang

2016-01-01

In addition to mutations in ITG2B or ITGB3 genes that cause defective αIIbβ3 expression and/or function in Glanzmann’s thrombasthenia patients, platelet dysfunction can be a result of genetic variability in proteins that mediate inside-out activation of αIIbβ3. The RASGRP2 gene is strongly expressed in platelets and neutrophils, where its encoded protein CalDAG-GEFI facilitates the activation of Rap1 and subsequent activation of integrins. We used next-generation sequencing (NGS) and whole-exome sequencing (WES) to identify 2 novel function-disrupting mutations in RASGRP2 that account for bleeding diathesis and platelet dysfunction in 2 unrelated families. By using a panel of 71 genes, we identified a homozygous change (c.1142C>T) in exon 10 of RASGRP2 in a 9-year-old child of Chinese origin (family 1). This variant led to a p.Ser381Phe substitution in the CDC25 catalytic domain of CalDAG-GEFI. In 2 Spanish siblings from family 2, WES identified a nonsense homozygous variation (c.337C>T) (p.Arg113X) in exon 5 of RASGRP2. CalDAG-GEFI expression was markedly reduced in platelets from all patients, and by using a novel in vitro assay, we found that the nucleotide exchange activity was dramatically reduced in CalDAG-GEFI p.Ser381Phe. Platelets from homozygous patients exhibited agonist-specific defects in αIIbβ3 integrin activation and aggregation. In contrast, α- and δ-granule secretion, platelet spreading, and clot retraction were not markedly affected. Integrin activation in the patients’ neutrophils was also impaired. These patients are the first cases of a CalDAG-GEFI deficiency due to homozygous RASGRP2 mutations that are linked to defects in both leukocyte and platelet integrin activation. PMID:27235135

Influenza Virus Mounts a Two-Pronged Attack on Host RNA Polymerase II Transcription.

PubMed

Bauer, David L V; Tellier, Michael; Martínez-Alonso, Mónica; Nojima, Takayuki; Proudfoot, Nick J; Murphy, Shona; Fodor, Ervin

2018-05-15

Influenza virus intimately associates with host RNA polymerase II (Pol II) and mRNA processing machinery. Here, we use mammalian native elongating transcript sequencing (mNET-seq) to examine Pol II behavior during viral infection. We show that influenza virus executes a two-pronged attack on host transcription. First, viral infection causes decreased Pol II gene occupancy downstream of transcription start sites. Second, virus-induced cellular stress leads to a catastrophic failure of Pol II termination at poly(A) sites, with transcription often continuing for tens of kilobases. Defective Pol II termination occurs independently of the ability of the viral NS1 protein to interfere with host mRNA processing. Instead, this termination defect is a common effect of diverse cellular stresses and underlies the production of previously reported downstream-of-gene transcripts (DoGs). Our work has implications for understanding not only host-virus interactions but also fundamental aspects of mammalian transcription. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

SSD1, which encodes a plant-specific novel protein, controls plant elongation by regulating cell division in rice.

PubMed

Asano, Kenji; Miyao, Akio; Hirochika, Hirohiko; Kitano, Hidemi; Matsuoka, Makoto; Ashikari, Motoyuki

2010-01-01

Plant height is one of the most important traits in crop improvement. Therefore revealing the mechanism of plant elongation and controlling plant height in accordance with breeding object is important. In this study we analyzed a novel dwarf mutant, ssd1, of which phenotype is different from typical GA- or BR-related dwarf phenotype. ssd1 exhibits pleiotropic defects in elongation of various organs such as stems, roots, leaves, and flowers. ssd1 also shows abnormal cell files and shapes, which suggests defects of normal cell division in the mutant. Map-based cloning and complementation test demonstrated that the dwarf phenotype in ssd1 mutant was caused by insertion of retrotransposon in a gene, which encodes plant-specific protein with unknown biochemical function. A BLAST search revealed that SSD1-like genes exist in diverse plant species, including monocots and dicots, but not fern and moss. Our results demonstrate that SSD1 controls plant elongation by controlling cell division in higher plants.

Dolichol-phosphate mannose synthase depletion in zebrafish leads to dystrophic muscle with hypoglycosylated α-dystroglycan.

PubMed

Marchese, Maria; Pappalardo, Andrea; Baldacci, Jacopo; Verri, Tiziano; Doccini, Stefano; Cassandrini, Denise; Bruno, Claudio; Fiorillo, Chiara; Garcia-Gil, Mercedes; Bertini, Enrico; Pitto, Letizia; Santorelli, Filippo M

2016-08-12

Defective dolichol-phosphate mannose synthase (DPMS) complex is a rare cause of congenital muscular dystrophy associated with hypoglycosylation of alpha-dystroglycan (α-DG) in skeletal muscle. We used the zebrafish (Danio rerio) to model muscle abnormalities due to defects in the subunits of DPMS. The three zebrafish ortholog subunits (encoded by the dpm1, dpm2 and dpm3 genes, respectively) showed high similarity to the human proteins, and their expression displayed localization in the midbrain/hindbrain area and somites. Antisense morpholino oligonucleotides targeting each subunit were used to transiently deplete the dpm genes. The resulting morphant embryos showed early death, muscle disorganization, low DPMS complex activity, and increased levels of apoptotic nuclei, together with hypoglycosylated α-DG in muscle fibers, thus recapitulating most of the characteristics seen in patients with mutations in DPMS. Our results in zebrafish suggest that DPMS plays a role in stabilizing muscle structures and in apoptotic cell death. Copyright © 2016 Elsevier Inc. All rights reserved.

Chemical corrector treatment ameliorates increased seizure susceptibility in a mouse model of familial epilepsy.

PubMed

Yokoi, Norihiko; Fukata, Yuko; Kase, Daisuke; Miyazaki, Taisuke; Jaegle, Martine; Ohkawa, Toshika; Takahashi, Naoki; Iwanari, Hiroko; Mochizuki, Yasuhiro; Hamakubo, Takao; Imoto, Keiji; Meijer, Dies; Watanabe, Masahiko; Fukata, Masaki

2015-01-01

Epilepsy is one of the most common and intractable brain disorders. Mutations in the human gene LGI1, encoding a neuronal secreted protein, cause autosomal dominant lateral temporal lobe epilepsy (ADLTE). However, the pathogenic mechanisms of LGI1 mutations remain unclear. We classified 22 reported LGI1 missense mutations as either secretion defective or secretion competent, and we generated and analyzed two mouse models of ADLTE encoding mutant proteins representative of the two groups. The secretion-defective LGI1(E383A) protein was recognized by the ER quality-control machinery and prematurely degraded, whereas the secretable LGI1(S473L) protein abnormally dimerized and was selectively defective in binding to one of its receptors, ADAM22. Both mutations caused a loss of function, compromising intracellular trafficking or ligand activity of LGI1 and converging on reduced synaptic LGI1-ADAM22 interaction. A chemical corrector, 4-phenylbutyrate (4PBA), restored LGI1(E383A) folding and binding to ADAM22 and ameliorated the increased seizure susceptibility of the LGI1(E383A) model mice. This study establishes LGI1-related epilepsy as a conformational disease and suggests new therapeutic options for human epilepsy.

A Murine Model for Human ECO Syndrome Reveals a Critical Role of Intestinal Cell Kinase in Skeletal Development.

PubMed

Ding, Mengmeng; Jin, Li; Xie, Lin; Park, So Hyun; Tong, Yixin; Wu, Di; Chhabra, A Bobby; Fu, Zheng; Li, Xudong

2018-03-01

An autosomal-recessive inactivating mutation R272Q in the human intestinal cell kinase (ICK) gene caused profound multiplex developmental defects in human endocrine-cerebro-osteodysplasia (ECO) syndrome. ECO patients exhibited a wide variety of skeletal abnormalities, yet the underlying mechanisms by which ICK regulates skeletal development remained largely unknown. The goal of this study was to understand the structural and mechanistic basis underlying skeletal anomalies caused by ICK dysfunction. Ick R272Q knock-in transgenic mouse model not only recapitulated major ECO skeletal defects such as short limbs and polydactyly but also revealed a deformed spine with defective intervertebral disk. Loss of ICK function markedly reduced mineralization in the spinal column, ribs, and long bones. Ick mutants showed a significant decrease in the proliferation zone of long bones and the number of type X collagen-expressing hypertrophic chondrocytes in the spinal column and the growth plate of long bones. These results implicate that ICK plays an important role in bone and cartilage development by promoting chondrocyte proliferation and maturation. Our findings provided new mechanistic insights into the skeletal phenotype of human ECO and ECO-like syndromes.

DGCR6 at the proximal part of the DiGeorge critical region is involved in conotruncal heart defects

PubMed Central

Gao, Wenming; Higaki, Takashi; Eguchi-Ishimae, Minenori; Iwabuki, Hidehiko; Wu, Zhouying; Yamamoto, Eiichi; Takata, Hidemi; Ohta, Masaaki; Imoto, Issei; Ishii, Eiichi; Eguchi, Mariko

2015-01-01

Cardiac anomaly is one of the hallmarks of DiGeorge syndrome (DGS), observed in approximately 80% of patients. It often shows a characteristic morphology, termed as conotruncal heart defects. In many cases showing only the conotruncal heart defect, deletion of 22q11.2 region cannot be detected by fluorescence in situ hybridization (FISH), which is used to detect deletion in DGS. We investigated the presence of genomic aberrations in six patients with congenital conotruncal heart defects, who show no deletion at 22q11.2 in an initial screening by FISH. In these patients, no abnormalities were identified in the coding region of the TBX1 gene, one of the key genes responsible for the phenotype of DGS. However, when copy number alteration was analyzed by high-resolution array analysis, a small deletion or duplication in the proximal end of DiGeorge critical region was detected in two patients. The affected region contains the DGCR6 and PRODH genes. DGCR6 has been reported to affect the expression of the TBX1 gene. Our results suggest that altered dosage of gene(s) other than TBX1, possibly DGCR6, may also be responsible for the development of conotruncal heart defects observed in patients with DGS and, in particular, in those with stand-alone conotruncal heart defects. PMID:27081520

Mutations in Protein-Binding Hot-Spots on the Hub Protein Smad3 Differentially Affect Its Protein Interactions and Smad3-Regulated Gene Expression

PubMed Central

Schiro, Michelle M.; Stauber, Sara E.; Peterson, Tami L.; Krueger, Chateen; Darnell, Steven J.; Satyshur, Kenneth A.; Drinkwater, Norman R.; Newton, Michael A.; Hoffmann, F. Michael

2011-01-01

Background Hub proteins are connected through binding interactions to many other proteins. Smad3, a mediator of signal transduction induced by transforming growth factor beta (TGF-β), serves as a hub protein for over 50 protein-protein interactions. Different cellular responses mediated by Smad3 are the product of cell-type and context dependent Smad3-nucleated protein complexes acting in concert. Our hypothesis is that perturbation of this spectrum of protein complexes by mutation of single protein-binding hot-spots on Smad3 will have distinct consequences on Smad3-mediated responses. Methodology/Principal Findings We mutated 28 amino acids on the surface of the Smad3 MH2 domain and identified 22 Smad3 variants with reduced binding to subsets of 17 Smad3-binding proteins including Smad4, SARA, Ski, Smurf2 and SIP1. Mutations defective in binding to Smad4, e.g., D408H, or defective in nucleocytoplasmic shuttling, e.g., W406A, were compromised in modulating the expression levels of a Smad3-dependent reporter gene or six endogenous Smad3-responsive genes: Mmp9, IL11, Tnfaip6, Fermt1, Olfm2 and Wnt11. However, the Smad3 mutants Y226A, Y297A, W326A, K341A, and E267A had distinct differences on TGF-β signaling. For example, K341A and Y226A both reduced the Smad3-mediated activation of the reporter gene by ∼50% but K341A only reduced the TGF-β inducibilty of Olfm2 in contrast to Y226A which reduced the TGF-β inducibility of all six endogenous genes as severely as the W406A mutation. E267A had increased protein binding but reduced TGF-β inducibility because it caused higher basal levels of expression. Y297A had increased TGF-β inducibility because it caused lower Smad3-induced basal levels of gene expression. Conclusions/Significance Mutations in protein binding hot-spots on Smad3 reduced the binding to different subsets of interacting proteins and caused a range of quantitative changes in the expression of genes induced by Smad3. This approach should be useful for unraveling which Smad3 protein complexes are critical for specific biological responses. PMID:21949838

Mutations in protein-binding hot-spots on the hub protein Smad3 differentially affect its protein interactions and Smad3-regulated gene expression.

PubMed

Schiro, Michelle M; Stauber, Sara E; Peterson, Tami L; Krueger, Chateen; Darnell, Steven J; Satyshur, Kenneth A; Drinkwater, Norman R; Newton, Michael A; Hoffmann, F Michael

2011-01-01

Hub proteins are connected through binding interactions to many other proteins. Smad3, a mediator of signal transduction induced by transforming growth factor beta (TGF-β), serves as a hub protein for over 50 protein-protein interactions. Different cellular responses mediated by Smad3 are the product of cell-type and context dependent Smad3-nucleated protein complexes acting in concert. Our hypothesis is that perturbation of this spectrum of protein complexes by mutation of single protein-binding hot-spots on Smad3 will have distinct consequences on Smad3-mediated responses. We mutated 28 amino acids on the surface of the Smad3 MH2 domain and identified 22 Smad3 variants with reduced binding to subsets of 17 Smad3-binding proteins including Smad4, SARA, Ski, Smurf2 and SIP1. Mutations defective in binding to Smad4, e.g., D408H, or defective in nucleocytoplasmic shuttling, e.g., W406A, were compromised in modulating the expression levels of a Smad3-dependent reporter gene or six endogenous Smad3-responsive genes: Mmp9, IL11, Tnfaip6, Fermt1, Olfm2 and Wnt11. However, the Smad3 mutants Y226A, Y297A, W326A, K341A, and E267A had distinct differences on TGF-β signaling. For example, K341A and Y226A both reduced the Smad3-mediated activation of the reporter gene by ∼50% but K341A only reduced the TGF-β inducibilty of Olfm2 in contrast to Y226A which reduced the TGF-β inducibility of all six endogenous genes as severely as the W406A mutation. E267A had increased protein binding but reduced TGF-β inducibility because it caused higher basal levels of expression. Y297A had increased TGF-β inducibility because it caused lower Smad3-induced basal levels of gene expression. Mutations in protein binding hot-spots on Smad3 reduced the binding to different subsets of interacting proteins and caused a range of quantitative changes in the expression of genes induced by Smad3. This approach should be useful for unraveling which Smad3 protein complexes are critical for specific biological responses.

The RPN5 subunit of the 26s proteasome is essential for gametogenesis, sporophyte development, and complex assembly in Arabidopsis.

PubMed

Book, Adam J; Smalle, Jan; Lee, Kwang-Hee; Yang, Peizhen; Walker, Joseph M; Casper, Sarah; Holmes, James H; Russo, Laura A; Buzzinotti, Zachri W; Jenik, Pablo D; Vierstra, Richard D

2009-02-01

The 26S proteasome is an essential multicatalytic protease complex that degrades a wide range of intracellular proteins, especially those modified with ubiquitin. Arabidopsis thaliana and other plants use pairs of genes to encode most of the core subunits, with both of the isoforms often incorporated into the mature complex. Here, we show that the gene pair encoding the regulatory particle non-ATPase subunit (RPN5) has a unique role in proteasome function and Arabidopsis development. Homozygous rpn5a rpn5b mutants could not be generated due to a defect in male gametogenesis. While single rpn5b mutants appear wild-type, single rpn5a mutants display a host of morphogenic defects, including abnormal embryogenesis, partially deetiolated development in the dark, a severely dwarfed phenotype when grown in the light, and infertility. Proteasome complexes missing RPN5a are less stable in vitro, suggesting that some of the rpn5a defects are caused by altered complex integrity. The rpn5a phenotype could be rescued by expression of either RPN5a or RPN5b, indicating functional redundancy. However, abnormal phenotypes generated by overexpression implied that paralog-specific functions also exist. Collectively, the data point to a specific role for RPN5 in the plant 26S proteasome and suggest that its two paralogous genes in Arabidopsis have both redundant and unique roles in development.

Alpha-cardiac myosin heavy chain (MYH6) mutations affecting myofibril formation are associated with congenital heart defects.

PubMed

Granados-Riveron, Javier T; Ghosh, Tushar K; Pope, Mark; Bu'Lock, Frances; Thornborough, Christopher; Eason, Jacqueline; Kirk, Edwin P; Fatkin, Diane; Feneley, Michael P; Harvey, Richard P; Armour, John A L; David Brook, J

2010-10-15

Congenital heart defects (CHD) are collectively the most common form of congenital malformation. Studies of human cases and animal models have revealed that mutations in several genes are responsible for both familial and sporadic forms of CHD. We have previously shown that a mutation in MYH6 can cause an autosomal dominant form of atrial septal defect (ASD), whereas others have identified mutations of the same gene in patients with hypertrophic and dilated cardiomyopathy. In the present study, we report a mutation analysis of MYH6 in patients with a wide spectrum of sporadic CHD. The mutation analysis of MYH6 was performed in DNA samples from 470 cases of isolated CHD using denaturing high-performance liquid chromatography and sequence analysis to detect point mutations and small deletions or insertions, and multiplex amplifiable probe hybridization to detect partial or complete copy number variations. One non-sense mutation, one splicing site mutation and seven non-synonymous coding mutations were identified. Transfection of plasmids encoding mutant and non-mutant green fluorescent protein-MYH6 fusion proteins in mouse myoblasts revealed that the mutations A230P and A1366D significantly disrupt myofibril formation, whereas the H252Q mutation significantly enhances myofibril assembly in comparison with the non-mutant protein. Our data indicate that functional variants of MYH6 are associated with cardiac malformations in addition to ASD and provide a novel potential mechanism. Such phenotypic heterogeneity has been observed in other genes mutated in CHD.

Pathogen Proliferation Governs the Magnitude but Compromises the Function of CD8 T Cells1

PubMed Central

Sad, Subash; Dudani, Renu; Gurnani, Komal; Russell, Marsha; van Faassen, Henk; Finlay, Brett; Krishnan, Lakshmi

2014-01-01

CD8+ T cell memory is critical for protection against many intracellular pathogens. However, it is not clear how pathogen virulence influences the development and function of CD8+ T cells. Salmonella typhimurium (ST) is an intracellular bacterium that causes rapid fatality in susceptible mice and chronic infection in resistant strains. We have constructed recombinant mutants of ST, expressing the same immunodominant Ag OVA, but defective in various key virulence genes. We show that the magnitude of CD8+ T cell response correlates directly to the intracellular proliferation of ST. Wild-type ST displayed efficient intracellular proliferation and induced increased numbers of OVA-specific CD8+ T cells upon infection in mice. In contrast, mutants with defective Salmonella pathogenicity island II genes displayed poor intracellular proliferation and induced reduced numbers of OVA-specific CD8+ T cells. However, when functionality of the CD8+ T cell response was measured, mutants of ST induced a more functional response compared with the wild-type ST. Infection with wild-type ST, in contrast to mutants defective in pathogenicity island II genes, induced the generation of mainly effector-memory CD8+ T cells that expressed little IL-2, failed to mediate efficient cytotoxicity, and proliferated poorly in response to Ag challenge in vivo. Taken together, these results indicate that pathogens that proliferate rapidly and chronically in vivo may evoke functionally inferior memory CD8+ T cells which may promote the survival of the pathogen. PMID:18424704

PubMed Central

Stachenko, Sylvie

1983-01-01

With more women entering the labor market, concern about adverse effects of occupational exposure on reproductive health has been increasing. Of special importance are those agents which might cause birth defects and gene mutations. The fetus can be subject to chemical, biological, physical and ergonomic threats to its wellbeing. Most of the concern has been focused on the occupational dangers for pregnant women. However, the potential risks for the male reproductive system are being more widely recognized. PMID:21283300

The Roles of β-Oxidation and Cofactor Homeostasis in Peroxisome Distribution and Function in Arabidopsis thaliana

PubMed Central

Rinaldi, Mauro A.; Patel, Ashish B.; Park, Jaeseok; Lee, Koeun; Strader, Lucia C.; Bartel, Bonnie

2016-01-01

Key steps of essential metabolic pathways are housed in plant peroxisomes. We conducted a microscopy-based screen for anomalous distribution of peroxisomally targeted fluorescence in Arabidopsis thaliana. This screen uncovered 34 novel alleles in 15 genes affecting oil body mobilization, fatty acid β-oxidation, the glyoxylate cycle, peroxisome fission, and pexophagy. Partial loss-of-function of lipid-mobilization enzymes conferred peroxisomes clustered around retained oil bodies without other notable defects, suggesting that this microscopy-based approach was sensitive to minor perturbations, and that fatty acid β-oxidation rates in wild type are higher than required for normal growth. We recovered three mutants defective in PECTIN METHYLESTERASE31, revealing an unanticipated role in lipid mobilization for this cytosolic enzyme. Whereas mutations reducing fatty acid import had peroxisomes of wild-type size, mutations impairing fatty acid β-oxidation displayed enlarged peroxisomes, possibly caused by excess fatty acid β-oxidation intermediates in the peroxisome. Several fatty acid β-oxidation mutants also displayed defects in peroxisomal matrix protein import. Impairing fatty acid import reduced the large size of peroxisomes in a mutant defective in the PEROXISOMAL NAD+ TRANSPORTER (PXN), supporting the hypothesis that fatty acid accumulation causes pxn peroxisome enlargement. The diverse mutants isolated in this screen will aid future investigations of the roles of β-oxidation and peroxisomal cofactor homeostasis in plant development. PMID:27605050