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Regulatory module network of basic\\/helix-loop-helix transcription factors in mouse brain  

Microsoft Academic Search

BACKGROUND: The basic\\/helix-loop-helix (bHLH) proteins are important components of the transcriptional regulatory network, controlling a variety of biological processes, especially the development of the central nervous system. Until now, reports describing the regulatory network of the bHLH transcription factor (TF) family have been scarce. In order to understand the regulatory mechanisms of bHLH TFs in mouse brain, we inferred their

Jing Li; Zijing J Liu; Yuchun C Pan; Qi Liu; Xing Fu; Nigel GF Cooper; Yixue X Li; Mengsheng S Qiu; Tieliu L Shi



A Triple Helix-Loop-Helix/Basic Helix-Loop-Helix Cascade Controls Cell Elongation Downstream of Multiple Hormonal and Environmental Signaling Pathways in Arabidopsis[C][W  

PubMed Central

Environmental and endogenous signals, including light, temperature, brassinosteroid (BR), and gibberellin (GA), regulate cell elongation largely by influencing the expression of the paclobutrazol-resistant (PRE) family helix-loop-helix (HLH) factors, which promote cell elongation by interacting antagonistically with another HLH factor, IBH1. However, the molecular mechanism by which PREs and IBH1 regulate gene expression has remained unknown. Here, we show that IBH1 interacts with and inhibits a DNA binding basic helix-loop-helix (bHLH) protein, HBI1, in Arabidopsis thaliana. Overexpression of HBI1 increased hypocotyl and petiole elongation, whereas dominant inactivation of HBI1 and its homologs caused a dwarf phenotype, indicating that HBI1 is a positive regulator of cell elongation. In vitro and in vivo experiments showed that HBI1 directly bound to the promoters and activated two EXPANSIN genes encoding cell wall–loosening enzymes; HBI1’s DNA binding and transcriptional activities were inhibited by IBH1, but the inhibitory effects of IBH1 were abolished by PRE1. The results indicate that PREs activate the DNA binding bHLH factor HBI1 by sequestering its inhibitor IBH1. Altering each of the three factors affected plant sensitivities to BR, GA, temperature, and light. Our study demonstrates that PREs, IBH1, and HBI1 form a chain of antagonistic switches that regulates cell elongation downstream of multiple external and endogenous signals. PMID:23221598

Bai, Ming-Yi; Fan, Min; Oh, Eunkyoo; Wang, Zhi-Yong



Helix–loop–helix/basic helix–loop–helix transcription factor network represses cell elongation in Arabidopsis through an apparent incoherent feed-forward loop  

PubMed Central

Cell elongation is promoted by different environmental and hormonal signals, involving light, temperature, brassinosteroid (BR), and gibberellin, that inhibit the atypical basic helix–loop–helix (bHLH) transcription factor INCREASED LEAF INCLINATION1 BINDING bHLH1 (IBH1). Ectopic accumulation of IBH1 causes a severe dwarf phenotype, but the cell elongation suppression mechanism is still not well understood. Here, we identified a close homolog of IBH1, IBH1-LIKE1 (IBL1), that also antagonized BR responses and cell elongation. Genome-wide expression analyses showed that IBH1 and IBL1 act interdependently downstream of the BRASSINAZOLE-RESISTANT1 (BZR1)–PHYTOCHROME-INTERACTING FACTOR 4 (PIF4)–DELLA module. Although characterized as non-DNA binding, IBH1 repressed direct IBL1 transcription, and they both acted in tandem to suppress the expression of a common downstream helix–loop–helix (HLH)/bHLH network, thus forming an incoherent feed-forward loop. IBH1 and IBL1 together repressed the expression of PIF4, known to stimulate skotomorphogenesis synergistically with BZR1. Strikingly, PIF4 bound all direct and down-regulated HLH/bHLH targets of IBH1 and IBL1. Additional genome-wide comparisons suggested a model in which IBH1 antagonized PIF4 but not the PIF4–BZR1 dimer. PMID:24505057

Zhiponova, Miroslava K.; Morohashi, Kengo; Vanhoutte, Isabelle; Machemer-Noonan, Katja; Revalska, Miglena; Van Montagu, Marc; Grotewold, Erich; Russinova, Eugenia



A triple helix-loop-helix/basic helix-loop-helix cascade controls cell elongation downstream of multiple hormonal and environmental signaling pathways in Arabidopsis.  


Environmental and endogenous signals, including light, temperature, brassinosteroid (BR), and gibberellin (GA), regulate cell elongation largely by influencing the expression of the paclobutrazol-resistant (PRE) family helix-loop-helix (HLH) factors, which promote cell elongation by interacting antagonistically with another HLH factor, IBH1. However, the molecular mechanism by which PREs and IBH1 regulate gene expression has remained unknown. Here, we show that IBH1 interacts with and inhibits a DNA binding basic helix-loop-helix (bHLH) protein, HBI1, in Arabidopsis thaliana. Overexpression of HBI1 increased hypocotyl and petiole elongation, whereas dominant inactivation of HBI1 and its homologs caused a dwarf phenotype, indicating that HBI1 is a positive regulator of cell elongation. In vitro and in vivo experiments showed that HBI1 directly bound to the promoters and activated two EXPANSIN genes encoding cell wall-loosening enzymes; HBI1's DNA binding and transcriptional activities were inhibited by IBH1, but the inhibitory effects of IBH1 were abolished by PRE1. The results indicate that PREs activate the DNA binding bHLH factor HBI1 by sequestering its inhibitor IBH1. Altering each of the three factors affected plant sensitivities to BR, GA, temperature, and light. Our study demonstrates that PREs, IBH1, and HBI1 form a chain of antagonistic switches that regulates cell elongation downstream of multiple external and endogenous signals. PMID:23221598

Bai, Ming-Yi; Fan, Min; Oh, Eunkyoo; Wang, Zhi-Yong



The Basic Helix-Loop-Helix Transcription Factor PIF5 Acts on Ethylene Biosynthesis and Phytochrome Signaling by Distinct Mechanisms  

Technology Transfer Automated Retrieval System (TEKTRAN)

HYTOCHROME-INTERACTING FACTOR5 (PIF5), a basic helix-loop-helix transcription factor, interacts specifically with the photoactivated form of phytochrome B (phyB). Here, we report that dark-grown Arabidopsis thaliana seedlings overexpressing PIF5 (PIF5-OX) exhibit exaggerated apical hooks and short h...


Regulation of Arabidopsis Brassinosteroid Signaling by Atypical Basic Helix-Loop-Helix Proteins[C][W  

PubMed Central

Basic helix-loop-helix (bHLH) proteins are highly conserved transcription factors critical for cell proliferation and differentiation. Recent studies have implicated bHLH proteins in many plant signaling processes, including brassinosteroid (BR) signaling. Here, we report identification of two families of atypical bHLH proteins capable of modulating BR signaling. We found that activation-tagged bri1 suppressor 1-Dominant (atbs1-D), previously identified as a dominant suppressor of a weak BR receptor mutant bri1-301, was caused by overexpression of a 93–amino acid atypical bHLH protein lacking amino acids critical for DNA binding. Interestingly, atbs1-D only suppresses weak BR mutants, while overexpression of a truncated ATBS1 lacking the basic motif also rescues bri1-301, suggesting that ATBS1 likely stimulates BR signaling by sequestering negative BR signaling components. A yeast two-hybrid screen using ATBS1 as bait discovered four ATBS1-Interacting Factors (AIFs) that are members of another atypical bHLH protein subfamily. AIF1 exhibits an overlapping expression pattern with ATBS1 and its homologs and interacts with ATBS1 in vitro and in vivo. AIF1 overexpression nullifies the suppressive effect of atbs1-D on bri1-301 and results in dwarf transgenic plants resembling BR mutants. By contrast, silencing of AIF1 partially suppressed the bri1-301 phenotype. Our results suggested that plants use these atypical bHLH proteins to regulate BR signaling. PMID:20023194

Wang, Hao; Zhu, Yongyou; Fujioka, Shozo; Asami, Tadao; Li, Jiayang; Li, Jianming



Identification of a Novel Family of Oligodendrocyte Lineage-Specific Basic Helix–Loop–Helix Transcription Factors  

Microsoft Academic Search

Basic helix–loop–helix (bHLH) transcription factors have been identified for neurons and their precursors but not for glial cells. We have identified two bHLH factors, Oligo1 and Oligo2, that are specifically expressed in zones of neuroepithelium from which oligodendrocyte precursors emerge, as well as in the precursors themselves. Expression of Oligo2 in the spinal cord precedes that of platelet-derived growth factor

Qiao Zhou; Songli Wang; David J. Anderson



Iron-binding e3 ligase mediates iron response in plants by targeting basic helix-loop-helix transcription factors.  


Iron uptake and metabolism are tightly regulated in both plants and animals. In Arabidopsis (Arabidopsis thaliana), BRUTUS (BTS), which contains three hemerythrin (HHE) domains and a Really Interesting New Gene (RING) domain, interacts with basic helix-loop-helix transcription factors that are capable of forming heterodimers with POPEYE (PYE), a positive regulator of the iron deficiency response. BTS has been shown to have E3 ligase capacity and to play a role in root growth, rhizosphere acidification, and iron reductase activity in response to iron deprivation. To further characterize the function of this protein, we examined the expression pattern of recombinant ProBTS::?-GLUCURONIDASE and found that it is expressed in developing embryos and other reproductive tissues, corresponding with its apparent role in reproductive growth and development. Our findings also indicate that the interactions between BTS and PYE-like (PYEL) basic helix-loop-helix transcription factors occur within the nucleus and are dependent on the presence of the RING domain. We provide evidence that BTS facilitates 26S proteasome-mediated degradation of PYEL proteins in the absence of iron. We also determined that, upon binding iron at the HHE domains, BTS is destabilized and that this destabilization relies on specific residues within the HHE domains. This study reveals an important and unique mechanism for plant iron homeostasis whereby an E3 ubiquitin ligase may posttranslationally control components of the transcriptional regulatory network involved in the iron deficiency response. PMID:25452667

Selote, Devarshi; Samira, Rozalynne; Matthiadis, Anna; Gillikin, Jeffrey W; Long, Terri A



Overexpression of a Mutant Basic Helix-Loop-Helix Protein HFR1, HFR1-?N105, Activates a Branch Pathway of Light Signaling in Arabidopsis1  

PubMed Central

The HFR1, a basic helix-loop-helix protein, is required for a subset of phytochrome A-mediated photoresponses in Arabidopsis. Here, we show that overexpression of the HFR1-?N105 mutant, which lacks the N-terminal 105 amino acids, confers exaggerated photoresponses even in darkness. Physiological analysis implied that overexpression of HFR1-?N105 activated constitutively a branch pathway of light signaling that mediates a subset of photomorphogenic responses, including germination, de-etiolation, gravitropic hypocotyl growth, blocking of greening, and expression of some light-regulated genes such as CAB, DRT112, PSAE, PSBL, PORA, and XTR7, without affecting the light-responsiveness of anthocyanin accumulation and expression of other light-regulated genes such as CHS and PSBS. Although the end-of-day far-red light response and petiole elongation were suppressed in the HFR1-?N105-overexpressing plants, flowering time was not affected by HFR1-?N105. In addition, the HFR1-?N105-overexpressing plants showed hypersensitive photoresponses in the inhibition of hypocotyl elongation, dependently on phytochrome A, FHY1, and FHY3 under FR light or phyB under R light, respectively. Moreover, our double mutant analysis suggested that the hypersensitive photoresponse is due to functional cooperation between HFR1-?N105 and other light-signaling components including HY5, a basic leucine zipper protein. Taken together, our results of gain-of-function approach with HFR1-?N105 suggest the existence of a complex and important basic helix-loop-helix protein-mediated transcriptional network controlling a branch pathway of light signaling and provide a useful framework for further genetic dissection of light-signaling network in Arabidopsis. PMID:14645731

Yang, Ki-Young; Kim, Young-Mi; Lee, Seunghee; Song, Pill-Soon; Soh, Moon-Soo



Combinatorial control of muscle development by basic helix-loop-helix and MADS-box transcription factors.  

PubMed Central

Members of the MyoD family of muscle-specific basic helix-loop-helix (bHLH) proteins function within a genetic pathway to control skeletal muscle development. Mutational analyses of these factors suggested that their DNA binding domains mediated interaction with a coregulator required for activation of muscle-specific transcription. Members of the myocyte enhancer binding factor 2 (MEF2) family of MADS-box proteins are expressed at high levels in muscle and neural cells and at lower levels in several other cell types. MEF2 factors are unable to activate muscle gene expression alone, but they potentiate the transcriptional activity of myogenic bHLH proteins. This potentiation appears to be mediated by direct interactions between the DNA binding domains of these different types of transcription factors. Biochemical and genetic evidence suggests that MEF2 factors are the coregulators for myogenic bHLH proteins. The presence of MEF2 and cell-specific bHLH proteins in other cell types raises the possibility that these proteins may also cooperate to regulate other programs of cell-specific gene expression. We present a model to account for such cooperative interactions. Images Fig. 5 PMID:8790335

Molkentin, J D; Olson, E N



The basic-helix–loop–helix-PAS orphan MOP3 forms transcriptionally active complexes with circadian and hypoxia factors  

PubMed Central

We report that MOP3 is a general dimerization partner for a subset of the basic-helix–loop–helix (bHLH)-PER–ARNT–SIM (PAS) superfamily of transcriptional regulators. We demonstrated that MOP3 interacts with MOP4, CLOCK, hypoxia-inducible factor 1? (HIF1?), and HIF2?. A DNA selection protocol revealed that the MOP3-MOP4 heterodimer bound a CACGTGA-containing DNA element. Transient transfection experiments demonstrated that the MOP3-MOP4 and MOP3-CLOCK complexes bound this element in COS-1 cells and drove transcription from a linked luciferase reporter gene. We also deduced the high-affinity DNA binding sites for MOP3-HIF1? complex (TACGTGA) and used transient transfection experiments to demonstrate that the MOP3-HIF1? and MOP3-HIF2? heterodimers bound this element, drove transcription, and responded to cellular hypoxia. Finally, we found that MOP3 mRNA expression overlaps in a number of tissues with each of its four potential partner molecules in vivo. PMID:9576906

Hogenesch, John B.; Gu, Yi-Zhong; Jain, Sanjay; Bradfield, Christopher A.



TWIST family of basic helix-loop-helix transcription factors mediate human mesenchymal stem cell growth and commitment.  


The TWIST family of basic helix-loop-helix transcription factors, Twist-1 and Dermo-1 are known mediators of mesodermal tissue development and contribute to correct patterning of the skeleton. In this study, we demonstrate that freshly purified human bone marrow-derived mesenchymal stromal/stem cells (MSC) express high levels of Twist-1 and Dermo-1 which are downregulated following ex vivo expansion. Enforced expression of Twist-1 or Dermo-1 in human MSC cultures increased expression of the MSC marker, STRO-1, and the early osteogenic transcription factors, Runx2 and Msx2. Conversely, overexpression of Twist-1 and Dermo-1 was associated with a decrease in the gene expression of osteoblast-associated markers, bone morphogenic protein-2, bone sialoprotein, osteopontin, alkaline phosphatase and osteocalcin. High expressing Twist-1 or Dermo-1 MSC lines exhibited an enhanced proliferative potential of approximately 2.5-fold compared with control MSC populations that were associated with elevated levels of Id-1 and Id-2 gene expression. Functional studies demonstrated that high expressing Twist-1 and Dermo-1 MSC displayed a decreased capacity for osteo/chondrogenic differentiation and an enhanced capacity to undergo adipogenesis. These findings implicate the TWIST gene family members as potential mediators of MSC self-renewal and lineage commitment in postnatal skeletal tissues by exerting their effects on genes involved in the early stages of bone development. PMID:19609939

Isenmann, Sandra; Arthur, Agnieszka; Zannettino, Andrew C W; Turner, Jenna L; Shi, Songtao; Glackin, Carlotta A; Gronthos, Stan



Genome-wide identification and analysis of basic helix-loop-helix domains in dog, Canis lupus familiaris.  


The basic helix-loop-helix (bHLH) domain is a highly conserved amino acid motif that defines a group of DNA-binding transcription factors. bHLH proteins play essential regulatory roles in a variety of biological processes in animal, plant, and fungus. The domestic dog, Canis lupus familiaris, is a good model organism for genetic, physiological, and behavioral studies. In this study, we identified 115 putative bHLH genes in the dog genome. Based on a phylogenetic analysis, 51, 26, 14, 4, 12, and 4 dog bHLH genes were assigned to six separate groups (A-F); four bHLH genes were categorized as ''orphans''. Within-group evolutionary relationships inferred from the phylogenetic analysis were consistent with positional conservation, other conserved domains flanking the bHLH motif, and highly conserved intron/exon patterns in other vertebrates. Our analytical results confirmed the GenBank annotations of 89 dog bHLH proteins and provided information that could be used to update the annotations of the remaining 26 dog bHLH proteins. These data will provide good references for further studies on the structures and regulatory functions of bHLH proteins in the growth and development of dogs, which may help in understanding the mechanisms that underlie the physical and behavioral differences between dogs and wolves. PMID:25403511

Wang, Xu-Hua; Wang, Yong; Liu, A-Ke; Liu, Xiao-Ting; Zhou, Yang; Yao, Qin; Chen, Ke-Ping



The grape berry-specific basic helix–loop–helix transcription factor VvCEB1 affects cell size  

PubMed Central

The development of fleshy fruits involves complex physiological and biochemical changes. After fertilization, fruit growth usually begins with cell division, continues with both cell division and expansion, allowing fruit set to occur, and ends with cell expansion only. In spite of the economical importance of grapevine, the molecular mechanisms controlling berry growth are not fully understood. The present work identified and characterized Vitis vinifera cell elongation bHLH protein (VvCEB1), a basic helix–loop–helix (bHLH) transcription factor controlling cell expansion in grape. VvCEB1 was expressed specifically in berry-expanding tissues with a maximum around veraison. The study of VvCEB1 promoter activity in tomato confirmed its specific fruit expression during the expansion phase. Overexpression of VvCEB1 in grape embryos showed that this protein stimulates cell expansion and affects the expression of genes involved in cell expansion, including genes of auxin metabolism and signalling. Taken together, these data show that VvCEB1 is a fruit-specific bHLH transcription factor involved in grape berry development. PMID:23314819

Lecourieux, Fatma



Genome-Wide Analysis of Basic/Helix-Loop-Helix Transcription Factor Family in Rice and Arabidopsis1[W  

PubMed Central

The basic/helix-loop-helix (bHLH) transcription factors and their homologs form a large family in plant and animal genomes. They are known to play important roles in the specification of tissue types in animals. On the other hand, few plant bHLH proteins have been studied functionally. Recent completion of whole genome sequences of model plants Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) allows genome-wide analysis and comparison of the bHLH family in flowering plants. We have identified 167 bHLH genes in the rice genome, and their phylogenetic analysis indicates that they form well-supported clades, which are defined as subfamilies. In addition, sequence analysis of potential DNA-binding activity, the sequence motifs outside the bHLH domain, and the conservation of intron/exon structural patterns further support the evolutionary relationships among these proteins. The genome distribution of rice bHLH genes strongly supports the hypothesis that genome-wide and tandem duplication contributed to the expansion of the bHLH gene family, consistent with the birth-and-death theory of gene family evolution. Bioinformatics analysis suggests that rice bHLH proteins can potentially participate in a variety of combinatorial interactions, endowing them with the capacity to regulate a multitude of transcriptional programs. In addition, similar expression patterns suggest functional conservation between some rice bHLH genes and their close Arabidopsis homologs. PMID:16896230

Li, Xiaoxing; Duan, Xuepeng; Jiang, Haixiong; Sun, Yujin; Tang, Yuanping; Yuan, Zheng; Guo, Jingkang; Liang, Wanqi; Chen, Liang; Yin, Jingyuan; Ma, Hong; Wang, Jian; Zhang, Dabing



Phylogeny, Functional Annotation, and Protein Interaction Network Analyses of the Xenopus tropicalis Basic Helix-Loop-Helix Transcription Factors  

PubMed Central

The previous survey identified 70 basic helix-loop-helix (bHLH) proteins, but it was proved to be incomplete, and the functional information and regulatory networks of frog bHLH transcription factors were not fully known. Therefore, we conducted an updated genome-wide survey in the Xenopus tropicalis genome project databases and identified 105 bHLH sequences. Among the retrieved 105 sequences, phylogenetic analyses revealed that 103 bHLH proteins belonged to 43 families or subfamilies with 46, 26, 11, 3, 15, and 4 members in the corresponding supergroups. Next, gene ontology (GO) enrichment analyses showed 65 significant GO annotations of biological processes and molecular functions and KEGG pathways counted in frequency. To explore the functional pathways, regulatory gene networks, and/or related gene groups coding for Xenopus tropicalis bHLH proteins, the identified bHLH genes were put into the databases KOBAS and STRING to get the signaling information of pathways and protein interaction networks according to available public databases and known protein interactions. From the genome annotation and pathway analysis using KOBAS, we identified 16 pathways in the Xenopus tropicalis genome. From the STRING interaction analysis, 68 hub proteins were identified, and many hub proteins created a tight network or a functional module within the protein families. PMID:24312906

Chen, Deyu



Caught red-handed: Rc encodes a basic helix-loop-helix protein conditioning red pericarp in rice.  


Rc is a domestication-related gene required for red pericarp in rice (Oryza sativa). The red grain color is ubiquitous among the wild ancestors of O. sativa, in which it is closely associated with seed shattering and dormancy. Rc encodes a basic helix-loop-helix (bHLH) protein that was fine-mapped to an 18.5-kb region on rice chromosome 7 using a cross between Oryza rufipogon (red pericarp) and O. sativa cv Jefferson (white pericarp). Sequencing of the alleles from both mapping parents as well as from two independent genetic stocks of Rc revealed that the dominant red allele differed from the recessive white allele by a 14-bp deletion within exon 6 that knocked out the bHLH domain of the protein. A premature stop codon was identified in the second mutant stock that had a light red pericarp. RT-PCR experiments confirmed that the Rc gene was expressed in both red- and white-grained rice but that a shortened transcript was present in white varieties. Phylogenetic analysis, supported by comparative mapping in rice and maize (Zea mays), showed that Rc, a positive regulator of proanthocyanidin, is orthologous with INTENSIFIER1, a negative regulator of anthocyanin production in maize, and is not in the same clade as rice bHLH anthocyanin regulators. PMID:16399804

Sweeney, Megan T; Thomson, Michael J; Pfeil, Bernard E; McCouch, Susan



Dominant alleles of the basic helix-loop-helix transcription factor ATR2 activate stress-responsive genes in Arabidopsis.  

PubMed Central

Members of the R/B basic helix-loop-helix (bHLH) family of plant transcription factors are involved in a variety of growth and differentiation processes. We isolated a dominant mutation in an R/B-related bHLH transcription factor in the course of studying Arabidopsis tryptophan pathway regulation. This mutant, atr2D, displayed increased expression of several tryptophan genes as well as a subset of other stress-responsive genes. The atr2D mutation creates an aspartate to asparagine change at a position that is highly conserved in R/B factors. Substitutions of other residues with uncharged side chains at this position also conferred dominant phenotypes. Moreover, overexpression of mutant atr2D, but not wild-type ATR2, conferred pleiotropic effects, including reduced size, dark pigmentation, and sterility. Therefore, atr2D is likely to be an altered-function allele that identifies a key regulatory site in the R/B factor coding sequence. Double-mutant analysis with atr1D, an overexpression allele of the ATR1 Myb factor previously isolated in tryptophan regulation screens, showed that atr2D and atr1D have additive effects on tryptophan regulation and are likely to act through distinct mechanisms to activate tryptophan genes. The dominant atr mutations thus provide tools for altering tryptophan metabolism in plants. PMID:12136026

Smolen, Gromoslaw A; Pawlowski, Laura; Wilensky, Sharon E; Bender, Judith



The basic helix-loop-helix leucine zipper transcription factor Mitf is conserved in Drosophila and functions in eye development.  

PubMed Central

The MITF protein is a member of the MYC family of basic helix-loop-helix leucine zipper (bHLH-Zip) transcription factors and is most closely related to the TFE3, TFEC, and TFEB proteins. In the mouse, MITF is required for the development of several different cell types, including the retinal pigment epithelial (RPE) cells of the eye. In Mitf mutant mice, the presumptive RPE cells hyperproliferate, abnormally express the retinal transcriptional regulator Pax6, and form an ectopic neural retina. Here we report the structure of the Mitf gene in Drosophila and demonstrate expression during embryonic development and in the eye-antennal imaginal disc. In vitro, transcriptional regulation by Drosophila Mitf, like its mouse counterpart, is modified by the Eyeless (Drosophila Pax6) transcription factor. In vivo, targeted expression of wild-type or dominant-negative Drosophila Mitf results in developmental abnormalities reminiscent of Mitf function in mouse eye development. Our results suggest that the Mitf gene is the original member of the Mitf-Tfe subfamily of bHLH-Zip proteins and that its developmental function is at least partially conserved between vertebrates and invertebrates. These findings further support the common origin of the vertebrate and invertebrate eyes. PMID:15166150

Hallsson, Jón H; Haflidadóttir, Benedikta S; Stivers, Chad; Odenwald, Ward; Arnheiter, Heinz; Pignoni, Francesca; Steingrímsson, Eiríkur



Heterogeneity of myotubes generated by the MyoD and E12 basic helix-loop-helix transcription factors in otherwise non-differentiation growth conditions.  


We used a synthetic biology approach to produce myotubes from mammalian C2C12 myoblasts in non-differentiation growth conditions using the expression of basic helix-loop-helix transcription factors, MyoD and E12, in various combinations and configurations. Our approach not only recapitulated the basics of muscle development and physiology, as the obtained myotubes showed qualities similar to those seen in striated muscle fibers in vivo, but also allowed for the synthesis of populations of myotubes which assumed distinct morphology, myofibrillar development and Ca(2+) dynamics. This fashioned class of biomaterials is suitable for the building blocks of soft actuators in micro-scale biomimetic robotics. This production line strategy can be embraced in reparative medicine as synthetic human myotubes with predetermined morphological/functional properties could be obtained using this very approach. This methodology can be adopted beyond striated muscle for the engineering of other tissue components/cells whose differentiation is governed by the principles of basic helix-loop-helix transcription factors, as in the case, for example, of neural or immune cell types. PMID:24360578

Grubiši?, Vladimir; Gottipati, Manoj K; Stout, Randy F; Grammer, J Robert; Parpura, Vladimir



Iron-Binding E3 Ligase Mediates Iron Response in Plants by Targeting Basic Helix-Loop-Helix Transcription Factors1[OPEN  

PubMed Central

Iron uptake and metabolism are tightly regulated in both plants and animals. In Arabidopsis (Arabidopsis thaliana), BRUTUS (BTS), which contains three hemerythrin (HHE) domains and a Really Interesting New Gene (RING) domain, interacts with basic helix-loop-helix transcription factors that are capable of forming heterodimers with POPEYE (PYE), a positive regulator of the iron deficiency response. BTS has been shown to have E3 ligase capacity and to play a role in root growth, rhizosphere acidification, and iron reductase activity in response to iron deprivation. To further characterize the function of this protein, we examined the expression pattern of recombinant ProBTS::?-GLUCURONIDASE and found that it is expressed in developing embryos and other reproductive tissues, corresponding with its apparent role in reproductive growth and development. Our findings also indicate that the interactions between BTS and PYE-like (PYEL) basic helix-loop-helix transcription factors occur within the nucleus and are dependent on the presence of the RING domain. We provide evidence that BTS facilitates 26S proteasome-mediated degradation of PYEL proteins in the absence of iron. We also determined that, upon binding iron at the HHE domains, BTS is destabilized and that this destabilization relies on specific residues within the HHE domains. This study reveals an important and unique mechanism for plant iron homeostasis whereby an E3 ubiquitin ligase may posttranslationally control components of the transcriptional regulatory network involved in the iron deficiency response. PMID:25452667

Selote, Devarshi; Samira, Rozalynne; Matthiadis, Anna; Gillikin, Jeffrey W.; Long, Terri A.



The basic domain of myogenic basic helix-loop-helix (bHLH) proteins is the novel target for direct inhibition by another bHLH protein, Twist.  

PubMed Central

In vertebrates, the basic helix-loop-helix (bHLH) protein Twist may be involved in the negative regulation of cellular determination and in the differentiation of several lineages, including myogenesis, osteogenesis, and neurogenesis. Although it has been shown that mouse twist (M-Twist) (i) sequesters E proteins, thus preventing formation of myogenic E protein-MyoD complexes and (ii) inhibits the MEF2 transcription factor, a cofactor of myogenic bHLH proteins, overexpression of E proteins and MEF2 failed to rescue the inhibitory effects of M-Twist on MyoD. We report here that M-Twist physically interacts with the myogenic bHLH proteins in vitro and in vivo and that this interaction is required for the inhibition of MyoD by M-Twist. In contrast to the conventional HLH-HLH domain interaction formed in the MyoD/E12 heterodimer, this novel type of interaction uses the basic domains of the two proteins. While the MyoD HLH domain without the basic domain failed to interact with M-Twist, a MyoD peptide containing only the basic and helix 1 regions was sufficient to interact with M-Twist, suggesting that the basic domain contacts M-Twist. The replacement of three arginine residues by alanines in the M-Twist basic domain was sufficient to abolish both the binding and inhibition of MyoD by M-Twist, while the domain retained other M-Twist functions such as heterodimerization with an E protein and inhibition of MEF2 transactivation. These findings demonstrate that M-Twist interacts with MyoD through the basic domains, thereby inhibiting MyoD. PMID:9343420

Hamamori, Y; Wu, H Y; Sartorelli, V; Kedes, L



An-1 Encodes a Basic Helix-Loop-Helix Protein That Regulates Awn Development, Grain Size, and Grain Number in Rice[C][W][OPEN  

PubMed Central

Long awns are important for seed dispersal in wild rice (Oryza rufipogon), but are absent in cultivated rice (Oryza sativa). The genetic mechanism involved in loss-of-awn in cultivated rice remains unknown. We report here the molecular cloning of a major quantitative trait locus, An-1, which regulates long awn formation in O. rufipogon. An-1 encodes a basic helix-loop-helix protein, which regulates cell division. The nearly-isogenic line (NIL-An-1) carrying a wild allele An-1 in the genetic background of the awnless indica Guangluai4 produces long awns and longer grains, but significantly fewer grains per panicle compared with Guangluai4. Transgenic studies confirmed that An-1 positively regulates awn elongation, but negatively regulates grain number per panicle. Genetic variations in the An-1 locus were found to be associated with awn loss in cultivated rice. Population genetic analysis of wild and cultivated rice showed a significant reduction in nucleotide diversity of the An-1 locus in rice cultivars, suggesting that the An-1 locus was a major target for artificial selection. Thus, we propose that awn loss was favored and strongly selected by humans, as genetic variations at the An-1 locus that cause awn loss would increase grain numbers and subsequently improve grain yield in cultivated rice. PMID:24076974

Luo, Jianghong; Liu, Hui; Zhou, Taoying; Gu, Benguo; Huang, Xuehui; Shangguan, Yingying; Zhu, Jingjie; Li, Yan; Zhao, Yan; Wang, Yongchun; Zhao, Qiang; Wang, Ahong; Wang, Ziqun; Sang, Tao; Wang, Zixuan; Han, Bin



Proneural Basic Helix-Loop-Helix Proteins and Epidermal Growth Factor Receptor Signaling Coordinately Regulate Cell Type Specification and cdk Inhibitor Expression during Development?  

PubMed Central

Cell differentiation and cell cycle exit are coordinately regulated during development; however, the molecular logic underlying this regulation is not known. The Drosophila cdk inhibitor Dacapo (Dap) is one of the key cell cycle regulators that exhibit dynamic expression during development and contribute to the developmental regulation of the cell cycle. In this study, regulation of Dap expression during cell type specification was investigated. The expression of Dap in the R2 and R5 precursors of the developing eye and in the newly recruited leg disc femoral sense organ precursors was found to be controlled by the epidermal growth factor receptor signaling-regulated transcription factor Pointed (Pnt) and the proneural basic helix-loop-helix proteins Atonal (Ato) and Daughterless (Da). We show that Pnt, Ato, and Da regulate Dap expression directly through their respective binding sites precisely at the time when these transcription factors function to specify neural fates. These results show that Dap expression is directly regulated by developmental mechanisms that simultaneously control cell type specification. This is potentially a general mechanism by which the expression of key cell cycle regulators is coordinated with differentiation during normal development. The direct regulation of key cell cycle regulators by the differentiation factors ensures coordinated regulation of cell cycle and differentiation. PMID:17296729

Sukhanova, Madina J.; Deb, Dilip K.; Gordon, Gabriel M.; Matakatsu, Miho Tanaka; Du, Wei



The basic helix-loop-helix (bHLH) transcription factor DEC2 negatively regulates Twist1 through an E-box element.  


Differentiated embryo chondrocyte 2 (DEC2/Sharp-1/Bhlhe41), a basic helix-loop-helix (bHLH) transcription factor, has been shown to regulate the transcription of target genes by binding to their E-box elements. We identified a possible DEC2-response element (consensus E-box: CACGTG) in the promoter region of Twist1. Forced expression of DEC2 significantly repressed Twist1 promoter activity under normoxia and under hypoxia as assessed by a luciferase reporter assay. In addition, over-expression of DEC2 repressed Twist1 mRNA expression assessed by quantitative real-time PCR. Site-directed mutagenesis studies showed that mutagenesis of the consensus E-box sequence eliminated the ability of DEC2 to reduce the Twist1 promoter activity. Chromatin immunoprecipitation (ChIP) assays confirmed that the DEC2-mediated repression is primarily achieved by binding to the E-box in the Twist1 promoter. Knockdown of DEC2 by siRNA significantly attenuated the repression of Twist1 expression. DEC2 and Twist1 exhibit inversed protein expression patterns during development of mouse tongue embryo tissue. Given the fact that DEC2 protein is emerging as an important regulator in a vast array of cellular events, including cell differentiation, maturation of lymphocytes and the molecular clock, our study elucidates an important mechanism by which DEC2 regulates cellular function by modulating the expression of Twist1. PMID:25446074

Suzuki, Masatoshi; Sato, Fuyuki; Bhawal, Ujjal K



A genome-wide identification and analysis of the basic helix-loop-helix transcription factors in the ponerine ant, Harpegnathos saltator  

PubMed Central

Background The basic helix-loop-helix (bHLH) transcription factors and their homologs form a superfamily that plays essential roles in transcriptional networks of multiple developmental processes. bHLH family members have been identified in over 20 organisms, including fruit fly, zebrafish, human and mouse. Result In this study, we conducted a genome-wide survey for bHLH sequences, and identified 57 bHLH sequences encoded in complete genome sequence of the ponerine ant, Harpegnathos saltator. Phylogenetic analysis of the bHLH domain sequences classified these genes into 38 bHLH families with 23, 14, 10, 1, 8 and 1 members in group A, B, C, D, E and F, respectively. The number of PabHLHs (ponerine ant bHLHs) with introns is higher than many other insect species, and they are found to have introns with average lengths only inferior to those of pea aphid. In addition, two H. saltator bHLHs named PaCrp1 and PaSide locate on two separate contigs in the genome. Conclusions A putative full set of PabHLH genes is comparable with other insect species and genes encoding Oligo, MyoRb and Fig? were not found in genomes of all insect species of which bHLH family members have been identified. Moreover, in-family phylogenetic analyses indicate that the PabHLH genes are more closely related with Apis mellifera than others. The present study will serve as a solid foundation for further investigations into the structure and function of bHLH proteins in the regulation of H. saltator development. PMID:22938134



Obligate Heterodimerization of Arabidopsis Phytochromes C and E and Interaction with the PIF3 Basic Helix-Loop-Helix Transcription Factor[W  

PubMed Central

Phytochromes are dimeric chromoproteins that regulate plant responses to red (R) and far-red (FR) light. The Arabidopsis thaliana genome encodes five phytochrome apoproteins: type I phyA mediates responses to FR, and type II phyB–phyE mediate shade avoidance and classical R/FR-reversible responses. In this study, we describe the complete in vivo complement of homodimeric and heterodimeric type II phytochromes. Unexpectedly, phyC and phyE do not homodimerize and are present in seedlings only as heterodimers with phyB and phyD. Roles in light regulation of hypocotyl length, leaf area, and flowering time are demonstrated for heterodimeric phytochromes containing phyC or phyE. Heterodimers of phyC and chromophoreless phyB are inactive, indicating that phyC subunits require spectrally intact dimer partners to be active themselves. Consistent with the obligate heterodimerization of phyC and phyE, phyC is made unstable by removal of its phyB binding partner, and overexpression of phyE results in accumulation of phyE monomers. Following a pulse of red light, phyA, phyB, phyC, and phyD interact in vivo with the PHYTOCHROME INTERACTING FACTOR3 basic helix-loop-helix transcription factor, and this interaction is FR reversible. Therefore, most or all of the type I and type II phytochromes, including heterodimeric forms, appear to function through PIF-mediated pathways. These findings link an unanticipated diversity of plant R/FR photoreceptor structures to established phytochrome signaling mechanisms. PMID:19286967

Clack, Ted; Shokry, Ahmed; Moffet, Matt; Liu, Peng; Faul, Michael; Sharrock, Robert A.



Basic Helix-Loop-Helix Transcription Factor Bmsage Is Involved in Regulation of fibroin H-chain Gene via Interaction with SGF1 in Bombyx mori  

PubMed Central

Silk glands are specialized in the synthesis of several secretory proteins. Expression of genes encoding the silk proteins in Bombyx mori silk glands with strict territorial and developmental specificities is regulated by many transcription factors. In this study, we have characterized B. mori sage, which is closely related to sage in the fruitfly Drosophila melanogaster. It is termed Bmsage; it encodes transcription factor Bmsage, which belongs to the Mesp subfamily, containing a basic helix–loop–helix motif. Bmsage transcripts were detected specifically in the silk glands of B. mori larvae through RT-PCR analysis. Immunoblotting analysis confirmed the Bmsage protein existed exclusively in B. mori middle and posterior silk gland cells. Bmsage has a low level of expression in the 4th instar molting stages, which increases gradually in the 5th instar feeding stages and then declines from the wandering to the pupation stages. Quantitative PCR analysis suggested the expression level of Bmsage in a high silk strain was higher compared to a lower silk strain on day 3 of the larval 5th instar. Furthermore, far western blotting and co-immunoprecipitation assays showed the Bmsage protein interacted with the fork head transcription factor silk gland factor 1 (SGF1). An electrophoretic mobility shift assay showed the complex of Bmsage and SGF1 proteins bound to the A and B elements in the promoter of fibroin H-chain gene(fib-H), respectively. Luciferase reporter gene assays confirmed the complex of Bmsage and SGF1 proteins increased the expression of fib-H. Together, these results suggest Bmsage is involved in the regulation of the expression of fib-H by being together with SGF1 in B. mori PSG cells. PMID:24740008

Li, Qiong-Yan; Hu, Wen-Bo; Zhou, Meng-Ting; Nie, Hong-Yi; Zhang, Yin-Xia; Peng, Zhang-Chuan; Zhao, Ping; Xia, Qing-You



Hey Basic Helix-Loop-Helix Transcription Factors Are Repressors of GATA4 and GATA6 and Restrict Expression of the GATA Target Gene ANF in Fetal Hearts  

PubMed Central

The Hey basic helix-loop-helix transcription factors are downstream effectors of Notch signaling in the cardiovascular system. Mice lacking Hey2 develop cardiac hypertrophy, often associated with congenital heart defects, whereas combined Hey1/Hey2 deficiency leads to severe vascular defects and embryonic lethality around embryonic day E9.5. The molecular basis of these disorders is poorly understood, however, since target genes of Hey transcription factors in the affected tissues remain elusive. To identify genes regulated by Hey factors we have generated a conditional Hey1 knockout mouse. This strain was used to generate paired Hey2- and Hey1/2-deficient embryonic stem cell lines. Comparison of these cell lines by microarray analysis identified GATA4 and GATA6 as differentially expressed genes. Loss of Hey1/2 leads to elevated GATA4/6 and ANF mRNA levels in embryoid bodies, while forced expression of Hey factors strongly represses expression of the GATA4 and GATA6 promoter in various cell lines. In addition, the promoter activity of the GATA4/6 target gene ANF was inhibited by Hey1, Hey2, and HeyL. Protein interaction and mutation analyses suggest that repression is due to direct binding of Hey proteins to GATA4 and GATA6, blocking their transcriptional activity. In Hey2-deficient fetal hearts we observed elevated mRNA levels of ANF and CARP. Expression of ANF and Hey2 is normally restricted to the trabecular and compact myocardial layer, respectively. Intriguingly, loss of Hey2 leads to ectopic ANF expression in the compact layer, suggesting a direct role for Hey2 in limiting ANF expression in this cardiac compartment. PMID:16199874

Fischer, Andreas; Klattig, Jürgen; Kneitz, Burkhard; Diez, Holger; Maier, Manfred; Holtmann, Bettina; Englert, Christoph; Gessler, Manfred



Basic helix-loop-helix transcription factor BcbHLHpol functions as a positive regulator of pollen development in non-heading Chinese cabbage.  


Cytoplasmic male sterility (CMS) is a common trait in higher plants, and several transcription factors regulate pollen development. Previously, we obtained a basic helix-loop-helix transcription factor, BcbHLHpol, via suppression subtractive hybridization in non-heading Chinese cabbage. However, the regulatory function of BcbHLHpol during anther and pollen development remains unclear. In this study, BcbHLHpol was cloned, and its tissue-specific expression profile was analyzed. The results of real-time polymerase chain reaction showed that BcbHLHpol was highly expressed in maintainer buds and that the transcripts of BcbHLHpol significantly decreased in the buds of pol CMS. A virus-induced gene silencing vector that targets BcbHLHpol was constructed and transformed into Brassica campestris plants to further explore the function of BcbHLHpol. Male sterility and short stature were observed in BcbHLHpol-silenced plants. The degradation of tapetal cells was inhibited in BcbHLHpol-silenced plants, and nutrients were insufficiently supplied to the microspore. These phenomena resulted in pollen abortion. This result indicates that BcbHLHpol functions as a positive regulator in pollen development. Yeast two-hybrid and bimolecular fluorescence complementation assays revealed that BcbHLHpol interacted with BcSKP1 in the nucleus. This finding suggests that BcbHLHpol and BcSKP1 are positive coordinating regulators of pollen development. Quantitative real-time PCR indicated that BcbHLHpol and BcSKP1 can be induced at low temperatures. Thus, we propose that BcbHLHpol is necessary for meiosis. This study provides insights into the regulatory functions of the BcbHLHpol network during anther development. PMID:25147023

Liu, Tongkun; Li, Ying; Zhang, Changwei; Duan, Weike; Huang, Feiyi; Hou, Xilin



Relaxed Constraint and Evolutionary Rate Variation between Basic Helix-Loop-Helix Floral Anthocyanin Regulators in Ipomoea  

E-print Network

Anthocyanin Regulators in Ipomoea Matthew A. Streisfeld and Mark D. Rausher Department of Biology, Duke of anthocyanin pigmentation genes in flowers. We cloned the full-length coding region from 2 basic helix

Oregon, University of


Proprotein convertase PACE4 is down-regulated by the basic helix-loop-helix transcription factor hASH-1 and MASH-1.  

PubMed Central

PACE4 is a mammalian subtilisin-like proprotein convertase that activates transforming growth factor (TGF)-beta-related proteins such as bone morphogenetic protein 2 (BMP2), BMP4 and Nodal and exhibits a dynamic expression pattern during embryogenesis. We recently determined that the 1 kb 5'-upstream region of the PACE4 gene contains 12 E-box (E1-E12) elements and that an E-box cluster (E4-E9) acts as a negative regulator [Tsuji, Yoshida, Hasegawa, Bando, Yoshida, Koide, Mori and Matsuda (1999) J. Biochem. (Tokyo) 126, 494-502]. It is known that the mammalian achaete-scute homologue 1 (MASH-1) binds specifically to an E-box (CACCTG) sequence in collaboration with E47, a ubiquitously expressed basic helix-loop-helix (bHLH) factor. To identify the roles of the bHLH factor and E-box elements in regulating PACE4 gene expression in neural development, we analysed the effects of human achaete-scute homologue 1 (hASH-1) on PACE4 gene expression with various neuroblastoma cell lines. The expressions of PACE4 and hASH-1 are correlated inversely in these cell lines. The overexpression of hASH-1 or MASH-1 causes a marked decrease in endogenous PACE4 gene expression but has no effect on the expression of other subtilisin-like proprotein convertases such as furin, PC5/6 and PC7/8. In contrast, other neural bHLH factors (MATH-1, MATH-2, neurogenin 1, neurogenin 2, neurogenin 3 and E47) did not affect PACE4 gene expression. Furthermore, an E-box cluster was a negative regulatory element for the promoter activity in NBL-S cells expressing hASH-1 at high level as determined by a luciferase assay. Binding of hASH-1 to the E-box cluster was confirmed by gel mobility-shift assay. In the present study we identified the PACE4 gene as one of the targets of hASH-1, which is a key factor in the initiation of neural differentiation. These results suggest that the alteration of PACE4 gene expression by hASH-1 causes rapid changes in the biological activities of TGF-beta-related proteins via post-translational modification of these proteins. PMID:11736660

Yoshida, I; Koide, S; Hasegawa, S I; Nakagawara, A; Tsuji, A; Matsuda, Y



Effect of different basic helix-loop-helix leucine zipper factors on the glucose response unit of the L-type pyruvate kinase gene.  


Glucose-regulated transcription of the L-type pyruvate kinase (L-PK) gene is mediated through its glucose response element (GlRE/L4 box) composed of two degenerated E-boxes. Upstream stimulatory factor (USF) is a component of the transcriptional glucose response complex built up on the GlRE. Cooperation of the GlRE with the contiguous binding site (L3 box) for the orphan nuclear receptor hepatocyte nuclear factor 4 (HNF4) has also been suggested. We compared by transient transfection assays the effects of USF2a and other basic helix-loop-helix leucine zipper (bHLH-LZ) factors (TFE3, c-Myc, SREBP/ADD1) on the activity and glucose responsiveness of a minimal L-PK promoter directed by oligomerized glucose response units (L4L3 boxes). We found that: (i) although USF2a is intrinsically a moderate transcriptional activator, it has a strong stimulatory effect on the activity of the L4L3-based reporter construct in hepatocyte-derived cells and interferes with the glucose responsiveness; (ii) despite its potent ability as a transactivator, TFE3 alone is barely active on the GlRE in hepatocyte-derived cells; (iii) TFE3 as USF2a acts synergistically with HNF4 and abolishes glucose responsiveness of the promoter when overexpressed; (iv) in contrast, overexpression of HNF4 alone stimulates activity of the promoter without interfering with glucose responsiveness; (v) SREBP/ADD1 has a very weak activity on the L4L3 elements, only detectable in the presence of HNF4, and c-Myc does not interact with the GIRE of the L-PK promoter. Our studies indicate that different bHLH-LZ transcription factors known to recognize CACGTG-type E-boxes are not equivalent in acting through the L-PK glucose response element, with USF proteins being especially efficient in hepatocyte-derived cells. PMID:9699482

Moriizumi, S; Gourdon, L; Lefrançois-Martinez, A M; Kahn, A; Raymondjean, M



Basic Helix-Loop-Helix Transcription Factors JASMONATE-ASSOCIATED MYC2-LIKE1 (JAM1), JAM2, and JAM3 Are Negative Regulators of Jasmonate Responses in Arabidopsis1[W][OPEN  

PubMed Central

Jasmonates regulate transcriptional reprogramming during growth, development, and defense responses. Jasmonoyl-isoleucine, an amino acid conjugate of jasmonic acid (JA), is perceived by the protein complex composed of the F-box protein CORONATINE INSENSITIVE1 (COI1) and JASMONATE ZIM DOMAIN (JAZ) proteins, leading to the ubiquitin-dependent degradation of JAZ proteins. This activates basic helix-loop-helix-type MYC transcription factors to regulate JA-responsive genes. Here, we show that the expression of genes encoding other basic helix-loop-helix transcription factors, JASMONATE ASSOCIATED MYC2-LIKE1 (JAM1), JAM2, and JAM3, is positively regulated in a COI1- and MYC2-dependent manner in Arabidopsis (Arabidopsis thaliana). However, contrary to myc2, the jam1jam2jam3 triple mutant exhibited shorter roots when treated with methyl jasmonate (MJ), indicating enhanced responsiveness to JA. Our genome-wide expression analyses revealed that key jasmonate metabolic genes as well as a set of genes encoding transcription factors that regulate the JA-responsive metabolic genes are negatively regulated by JAMs after MJ treatment. Consistently, loss of JAM genes resulted in higher accumulation of anthocyanin in MJ-treated plants as well as higher accumulation of JA and 12-hydroxyjasmonic acid in wounded plants. These results show that JAMs negatively regulate the JA responses in a manner that is mostly antagonistic to MYC2. PMID:23852442

Sasaki-Sekimoto, Yuko; Jikumaru, Yusuke; Obayashi, Takeshi; Saito, Hikaru; Masuda, Shinji; Kamiya, Yuji; Ohta, Hiroyuki; Shirasu, Ken



The Neurogenic Basic Helix-Loop-Helix Transcription Factor NeuroD6 Enhances Mitochondrial Biogenesis and Bioenergetics to Confer Tolerance of Neuronal PC12-NeuroD6 Cells to the Mitochondrial Stressor Rotenone  

PubMed Central

The fundamental question of how and which neuronal specific transcription factors tailor mitochondrial bioenergetics to the need of developing neuronal cells has remained largely unexplored. In this study, we report that the neurogenic basic helix-loop-helix transcription factor NeuroD6 possesses mitochondrial biogenic properties by amplifying the mitochondrial DNA content and TFAM expression levels, a key regulator for mitochondrial biogenesis. NeuroD6-mediated increase in mitochondrial biogenesis in the neuronal progenitor-like PC12-NEUROD6 cells is concomitant with enhanced mitochondrial bioenergetic functions, including increased expression levels of specific subunits of respiratory complexes of the electron transport chain, elevated mitochondrial membrane potential and ATP levels produced by oxidative phosphorylation. Thus, NeuroD6 augments the bioenergetic capacity of PC12-NEUROD6 cells to generate an energetic reserve, which confers tolerance to the mitochondrial stressor, rotenone. We found that NeuroD6 induces an adaptive bioenergetic response throughout rotenone treatment involving maintenance of the mitochondrial membrane potential and ATP levels in conjunction with preservation of the actin network. In conclusion, our results support the concept that NeuroD6 plays an integrative role in regulating and coordinating the onset of neuronal differentiation with acquisition of adequate mitochondrial mass and energetic capacity to ensure energy demanding events, such as cytoskeletal remodeling, plasmalemmal expansion, and growth cone formation. PMID:22814253

Baxter, Kristin Kathleen; Uittenbogaard, Martine; Chiaramello, Anne



Antagonistic regulation of growth and immunity by the Arabidopsis basic helix-loop-helix transcription factor homolog of brassinosteroid enhanced expression2 interacting with increased leaf inclination1 binding bHLH1.  


Plants need to finely balance resources allocated to growth and immunity to achieve optimal fitness. A tradeoff between pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and brassinosteroid (BR)-mediated growth was recently reported, but more information about the underlying mechanisms is needed. Here, we identify the basic helix-loop-helix (bHLH) transcription factor homolog of brassinosteroid enhanced expression2 interacting with IBH1 (HBI1) as a negative regulator of PTI signaling in Arabidopsis (Arabidopsis thaliana). HBI1 expression is down-regulated in response to different PAMPs. HBI1 overexpression leads to reduced PAMP-triggered responses. This inhibition correlates with reduced steady-state expression of immune marker genes, leading to increased susceptibility to the bacterium Pseudomonas syringae. Overexpression of the HBI1-related bHLHs brassinosteroid enhanced expression2 (BEE2) and cryptochrome-interacting bHLH (CIB1) partially inhibits immunity, indicating that BEE2 and CIB1 may act redundantly with HBI1. In contrast to its expression pattern upon PAMP treatment, HBI1 expression is enhanced by BR treatment. Also, HBI1-overexpressing plants are hyperresponsive to BR and more resistant to the BR biosynthetic inhibitor brassinazole. HBI1 is nucleus localized, and a mutation in a conserved leucine residue within the first helix of the protein interaction domain impairs its function in BR signaling. Interestingly, HBI1 interacts with several inhibitory atypical bHLHs, which likely keep HBI1 under negative control. Hence, HBI1 is a positive regulator of BR-triggered responses, and the negative effect of PTI is likely due to the antagonism between BR and PTI signaling. This study identifies a novel component involved in the complex tradeoff between innate immunity and BR-regulated growth. PMID:24443525

Malinovsky, Frederikke Gro; Batoux, Martine; Schwessinger, Benjamin; Youn, Ji Hyun; Stransfeld, Lena; Win, Joe; Kim, Seong-Ki; Zipfel, Cyril



The neurogenic basic helix-loop-helix transcription factor NeuroD6 enhances mitochondrial biogenesis and bioenergetics to confer tolerance of neuronal PC12-NeuroD6 cells to the mitochondrial stressor rotenone  

SciTech Connect

The fundamental question of how and which neuronal specific transcription factors tailor mitochondrial biogenesis and bioenergetics to the need of developing neuronal cells has remained largely unexplored. In this study, we report that the neurogenic basic helix-loop-helix transcription factor NeuroD6 possesses mitochondrial biogenic properties by amplifying the mitochondrial DNA content and TFAM expression levels, a key regulator for mitochondrial biogenesis. NeuroD6-mediated increase in mitochondrial biogenesis in the neuronal progenitor-like PC12-NEUROD6 cells is concomitant with enhanced mitochondrial bioenergetic functions, including increased expression levels of specific subunits of respiratory complexes of the electron transport chain, elevated mitochondrial membrane potential and ATP levels produced by oxidative phosphorylation. Thus, NeuroD6 augments the bioenergetic capacity of PC12-NEUROD6 cells to generate an energetic reserve, which confers tolerance to the mitochondrial stressor, rotenone. We found that NeuroD6 induces an adaptive bioenergetic response throughout rotenone treatment involving maintenance of the mitochondrial membrane potential and ATP levels in conjunction with preservation of the actin network. In conclusion, our results support the concept that NeuroD6 plays an integrative role in regulating and coordinating the onset of neuronal differentiation with acquisition of adequate mitochondrial mass and energetic capacity to ensure energy demanding events, such as cytoskeletal remodeling, plasmalemmal expansion, and growth cone formation. -- Highlights: Black-Right-Pointing-Pointer NeuroD6 induces mitochondrial biogenesis in neuroprogenitor-like cells. Black-Right-Pointing-Pointer NeuroD6 augments the bioenergetic reserve of the neuronal PC12-NeuroD6 cells. Black-Right-Pointing-Pointer NeuroD6 increases the mitochondrial membrane potential and ATP levels. Black-Right-Pointing-Pointer NeuroD6 confers tolerance to rotenone via an adaptive mitochondrial response.

Baxter, Kristin Kathleen; Uittenbogaard, Martine [Department of Anatomy and Regenerative Biology, George Washington University Medical Center, Washington, DC (United States)] [Department of Anatomy and Regenerative Biology, George Washington University Medical Center, Washington, DC (United States); Chiaramello, Anne, E-mail: [Department of Anatomy and Regenerative Biology, George Washington University Medical Center, Washington, DC (United States)] [Department of Anatomy and Regenerative Biology, George Washington University Medical Center, Washington, DC (United States)



Antagonistic Regulation of Growth and Immunity by the Arabidopsis Basic Helix-Loop-Helix Transcription Factor HOMOLOG OF BRASSINOSTEROID ENHANCED EXPRESSION2 INTERACTING WITH INCREASED LEAF INCLINATION1 BINDING bHLH11[W][OPEN  

PubMed Central

Plants need to finely balance resources allocated to growth and immunity to achieve optimal fitness. A tradeoff between pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) and brassinosteroid (BR)-mediated growth was recently reported, but more information about the underlying mechanisms is needed. Here, we identify the basic helix-loop-helix (bHLH) transcription factor HOMOLOG OF BRASSINOSTEROID ENHANCED EXPRESSION2 INTERACTING WITH IBH1 (HBI1) as a negative regulator of PTI signaling in Arabidopsis (Arabidopsis thaliana). HBI1 expression is down-regulated in response to different PAMPs. HBI1 overexpression leads to reduced PAMP-triggered responses. This inhibition correlates with reduced steady-state expression of immune marker genes, leading to increased susceptibility to the bacterium Pseudomonas syringae. Overexpression of the HBI1-related bHLHs BRASSINOSTEROID ENHANCED EXPRESSION2 (BEE2) and CRYPTOCHROME-INTERACTING bHLH (CIB1) partially inhibits immunity, indicating that BEE2 and CIB1 may act redundantly with HBI1. In contrast to its expression pattern upon PAMP treatment, HBI1 expression is enhanced by BR treatment. Also, HBI1-overexpressing plants are hyperresponsive to BR and more resistant to the BR biosynthetic inhibitor brassinazole. HBI1 is nucleus localized, and a mutation in a conserved leucine residue within the first helix of the protein interaction domain impairs its function in BR signaling. Interestingly, HBI1 interacts with several inhibitory atypical bHLHs, which likely keep HBI1 under negative control. Hence, HBI1 is a positive regulator of BR-triggered responses, and the negative effect of PTI is likely due to the antagonism between BR and PTI signaling. This study identifies a novel component involved in the complex tradeoff between innate immunity and BR-regulated growth. PMID:24443525

Malinovsky, Frederikke Gro; Batoux, Martine; Schwessinger, Benjamin; Youn, Ji Hyun; Stransfeld, Lena; Win, Joe; Kim, Seong-Ki; Zipfel, Cyril



Regulation of Id1 and Its Association with Basic Helix-Loop- Helix Proteins during Nerve Growth Factor-Induced Differentiation of PC12 Cells  

Microsoft Academic Search

Cell differentiation in the nervous system is dictated by specific patterns of gene expression. We have investigatedtheroleofhelix-loop-helix(HLH)proteinsduringdifferentiationofPC12pheochromocytomacells in response to nerve growth factor. Gel mobility shift assays using PC12 cell nuclear extracts demonstrated that active basic HLH complexes exist throughout differentiation. Addition of exogeneous Id1 protein, a negative regulator of basic HLH proteins, disrupted specific complexes formed by PC12 cell




A Novel Molecular Recognition Motif Necessary for Targeting Photoactivated Phytochrom eS ignaling to Specif ic Basic Helix-Loop-Helix Transcription Factors  

Microsoft Academic Search

The phytochrome (phy) family of sensory photoreceptors (phyA to phyE) in Arabidopsis thaliana control plant developmental transitions in response to informational light signals throughout the life cycle. The photoactivated conformer of the photo- receptor Pfr has been shown to translocate into the nucleus where it induces changes in gene expression by an unknown mechanism. Here, we have identified two basic

Rajnish Khanna; Enamul Huq; Elise A. Kikis; Bassem Al-Sady; Christina Lanzatella; Peter H. Quaila


Evolutionary aspects of developmentally regulated helix-loop-helix transcription factors in striated muscle of jellyfish  

Microsoft Academic Search

The function of basic helix-loop-helix (bHLH) proteins in cell differentiation was shown to be conserved from Drosophila to vertebrates, exemplified by the function of MyoD in striated muscle differentiation. In phylogeny striated muscle tissue appears first in jellyfish and the question of its evolutionary position is controversially discussed. For this reason we have studied the developmental role of myogenic bHLH

Peter Müller; Katja Seipel; Nathalie Yanze; Susanne Reber-Müller; Ruth Streitwolf-Engel; Michael Stierwald; J. ürg Spring; Volker Schmid



Class A Helix-Loop-Helix Proteins Are Positive Regulators of Several Cyclin-dependent Kinase Inhibitors’ Promoter Activity and Negatively Affect Cell Growth  

Microsoft Academic Search

ABSTRACT The class A of basic helix-loop-helix (bHLH) proteins are ubiquitously expressed transcription factors playing a pivotal role in the regulation of cell growth and differentiation. We determined that enforced expression of all four different mammalian members of this family, E12, E47, E2-2, and HEB, suppresses the cell colony-forming efficiency of several cell lines. To gain insights into the mechanisms

Alfredo Pagliuca; Pasquale Gallo; Pasquale De Luca; Luigi Lani


Suppression of mammary epithelial cell differentiation by the helix-loop-helix protein Id-1  

SciTech Connect

Cell proliferation and differentiation are precisely coordinated during the development and maturation of the mammary gland, and this balance invariably is disrupted during carcinogenesis. Little is known about the cell-specific transcription factors that regulate these processes in the mammary gland. The mouse mammary epithelial cell line SCp2 grows well under standard culture conditions but arrests growth, forms alveolus-like structures, and expresses {beta}-casein, a differentiation marker, 4 to 5 days after exposure to basement membrane and lactogenic hormones (differentiation signals). The authors show that this differentiation entails a marked decline in the expression of Id-1, a helix-loop-helix (HLH) protein that inactivates basic HLH transcription factors in other cell types. SCp2 cells stably transfected with an Id-1 expression vector grew more rapidly than control cells under standard conditions, but in response to differentiation signals, they lost three-dimensional organization, invaded the basement membrane, and then resumed growth. SCp2 cells expressing an Id-1 antisense vector grew more slowly than controls; in response to differentiation signals, they remained stably growth arrested and fully differentiated, as did control cells. The authors suggest that Id-1 renders cells refractory to differentiation signals and receptive to growth signals by inactivating one or more basic HLH proteins that coordinate growth and differentiation in the mammary epithelium. 53 refs., 6 figs.

Desprez, P.; Hara, E.; Bissell, M.J. [Lawrence Berkeley Lab., CA (United States)] [and others



Salvador-warts-hippo pathway in a developmental checkpoint monitoring helix-loop-helix proteins.  


The E proteins and Id proteins are, respectively, the positive and negative heterodimer partners for the basic-helix-loop-helix protein family and as such contribute to a remarkably large number of cell-fate decisions. E proteins and Id proteins also function to inhibit or promote cell proliferation and cancer. Using a genetic modifier screen in Drosophila, we show that the Id protein Extramacrochaetae enables growth by suppressing activation of the Salvador-Warts-Hippo pathway of tumor suppressors, activation that requires transcriptional activation of the expanded gene by the E protein Daughterless. Daughterless protein binds to an intronic enhancer in the expanded gene, both activating the SWH pathway independently of the transmembrane protein Crumbs and bypassing the negative feedback regulation that targets the same expanded enhancer. Thus, the Salvador-Warts-Hippo pathway has a cell-autonomous function to prevent inappropriate differentiation due to transcription factor imbalance and monitors the intrinsic developmental status of progenitor cells, distinct from any responses to cell-cell interactions. PMID:25579975

Wang, Lan-Hsin; Baker, Nicholas E



Self-recognition behavior of a helix-loop-helix domain by a fragment scan.  


The inhibitors of DNA binding Id1-4 are helix-loop-helix (HLH) proteins that exert their biological function by interacting with members of the basic-HLH (bHLH) transcription-factor family. The HLH domains of the Id and bHLH proteins allow both self- and hetero-association. Due to their abnormal expression in cancer cells, the Id proteins are potential protein targets for cancer treatment. Suitable Id-protein inactivators should promote self-association and/or prevent hetero-association. In this work we evaluated the ability of the Id-protein HLH domain to recognize itself in form of short sequences extracted from the helical and loop regions. We performed a peptide scan of the Id1 HLH domain 64-106 based on three-residue overlapping octapeptides. Interaction of each octapeptide with the natively folded Id1 HLH domain was investigated by CD and fluorescence spectroscopy. The results from both techniques showed that the helix-based but not the loop-based octapeptides interacted with the Id1 HLH domain in the low-micromolar range. In contrast, a nitrotyrosine-containing analog of the Id1 HLH region, which was unable to reproduce the native-like conformation, quenched only the 2-amino-benzoyl-(Abz)-labeled loop-based octapeptides. This opposite self-recognition pattern suggests that the short helix-based and loop-based sequences should be able to distinguish different folding states of the Id1 HLH domain. This feature may be biologically relevant, as the Id proteins are predicted to behave as intrinsically disordered proteins, being in equilibrium between rapidly exchanging monomeric conformations and structurally better-defined homo-/heterodimers displaying the parallel four-helix bundle. PMID:24981796

Beisswenger, Michael; Cabrele, Chiara



Autoimmunogenicity of the helix-loop-helix DNA-binding domain  

Microsoft Academic Search

Nonimmunogenic character of native DNA, and its high immunogenicity when presented in complex with the DNA-binding proteins indicate that the latter might contain molecular triggers of anti-DNA response. To find if this is the case, we have evaluated the autoimmunogenic potential of the main DNA-binding domain of HIV-1 reverse transcriptase that belongs to the canonical helix-loop-helix type. BALB\\/c mice were

Natalia Petrakova; Lindvi Gudmundsdotter; Maryna Yermalovich; Sergey Belikov; Lars Eriksson; Pawan Pyakurel; Olle Johansson; Peter Biberfeld; Sören Andersson; Maria Isaguliants



Persistent expression of helix-loop-helix factor HES-1 prevents mammalian neural differentiation in the central nervous system.  

PubMed Central

In the developing mammalian central nervous system, neural precursor cells present in the ventricular zone determine their fate to become neurons or glial cells, migrate towards the outer layers and undergo terminal differentiation. The transcriptional repressor HES-1, a basic helix-loop-helix (bHLH) factor structurally related to the Drosophila hairy gene, is expressed at high levels throughout the ventricular zone, but the level decreases as neural differentiation proceeds. Because of this negative correlation, we tested whether continuous expression of HES-1 inhibits neural differentiation. A HES-1 and lacZ-transducing retrovirus (SG-HES1) and a control lacZ-transducing retrovirus (SG) were injected into the lateral ventricles of mouse embryos, and the fate of the infected neural precursor cells was examined by X-gal staining. The SG virus-infected cells migrated and differentiated into neurons and glial cells. In contrast, the cells infected with SG-HES1 virus remained in the ventricular/subventricular zone, decreased to approximately 10% in number as compared with that of the newborn during the postnatal 4-5 weeks and, when they survived, were present exclusively in the ependymal layer. Furthermore, whereas cultured neural precursor cells infected with SG virus became immunoreactive for neuronal and glial markers, the cells infected with SG-HES1 virus did not. These results show that persistent expression of HES-1 severely perturbs neuronal and glial differentiation. Images PMID:7909512

Ishibashi, M; Moriyoshi, K; Sasai, Y; Shiota, K; Nakanishi, S; Kageyama, R



Two Single Nucleotide Polymorphisms in the Human Nescient Helix Loop Helix 2 (NHLH2) Gene Reduce mRNA Stability and DNA Binding  

PubMed Central

Nescient Helix Loop Helix-2 (NHLH2) is a basic helix-loop-helix transcription factor, which has been implicated, using mouse knockouts, in adult body weight regulation and fertility. A scan of the known single nucleotide polymorphisms (SNPs) in the NHLH2 gene revealed one in the 3’ untranslated region (3’UTR), which lies within an AUUUA RNA stability motif. A second SNP is nonsynonymous within the coding region of NHLH2, and was found in a genome-wide association study for obesity. Both of these SNPs were examined for their effect on NLHL2 by creating mouse mimics and examining mRNA stability, and protein function in mouse hypothalamic cell lines. The 3’UTR SNP causes increased instability and, when the SNP-containing Nhlh2 3’UTR is attached to luciferase mRNA, reduced protein levels in cells. The nonsynonymous SNP at position 83 in the protein changes an alanine residue, conserved in NHLH2 orthologs through to Drosphilia sp. to a proline residue. This change affects migration of the protein on an SDS-PAGE gel, and appears to alter secondary structure of the protein, as predicted using in silico methods. These results provide functional information on two rare human SNPs in the NHLH2 gene. One of these has been linked to human obese phenotypes, while the other is present in a relatively high proportion of individuals. Given their effects on NHLH2 protein levels, both SNPs deserve further analysis in whether they are causative and/or additive for human body weight and fertility phenotypes. PMID:23026212

AL_Rayyan, Numan; Wankhade, Umesh; Bush, Korie; Good, Deborah J.



BuD, a helix–loop–helix DNA-binding domain for genome modification  

PubMed Central

DNA editing offers new possibilities in synthetic biology and biomedicine for modulation or modification of cellular functions to organisms. However, inaccuracy in this process may lead to genome damage. To address this important problem, a strategy allowing specific gene modification has been achieved through the addition, removal or exchange of DNA sequences using customized proteins and the endogenous DNA-repair machinery. Therefore, the engineering of specific protein–DNA interactions in protein scaffolds is key to providing ‘toolkits’ for precise genome modification or regulation of gene expression. In a search for putative DNA-binding domains, BurrH, a protein that recognizes a 19?bp DNA target, was identified. Here, its apo and DNA-bound crystal structures are reported, revealing a central region containing 19 repeats of a helix–loop–helix modular domain (BurrH domain; BuD), which identifies the DNA target by a single residue-to-nucleotide code, thus facilitating its redesign for gene targeting. New DNA-binding specificities have been engineered in this template, showing that BuD-derived nucleases (BuDNs) induce high levels of gene targeting in a locus of the human haemoglobin ? (HBB) gene close to mutations responsible for sickle-cell anaemia. Hence, the unique combination of high efficiency and specificity of the BuD arrays can push forward diverse genome-modification approaches for cell or organism redesign, opening new avenues for gene editing. PMID:25004980

Stella, Stefano; Molina, Rafael; López-Méndez, Blanca; Juillerat, Alexandre; Bertonati, Claudia; Daboussi, Fayza; Campos-Olivas, Ramon; Duchateau, Phillippe; Montoya, Guillermo



Human calcitonin gene regulation by helix-loop-helix recognition sequences.  

PubMed Central

Human calcitonin (CT) gene transcription is regulated by proximal 5' flanking sequences which mediate cAMP-induced expression, and by a distal basal enhancer region. Using transient expression of CT-CAT constructs, we showed that the basal enhancer is active in a CT-producing small cell lung cancer cell line (DMS53) and the thyroid C cell derived tumor line, TT, but is inactive in non-CT-producing cell lines. In deletional and direct mutational analyses of the distal enhancer region, disruption of two elements resembling recognition sequences for the helix-loop-helix (HLH) family of transcriptional regulatory proteins resulted in a significant loss of basal transcriptional enhancer action. These results suggest that HLH recognition motifs may mediate a significant portion of constitutive CT gene transcriptional activity in these cells. Nuclear protein extracts from DMS53 cells formed specific binding complexes with oligonucleotides containing two of these candidate enhancer sequences. However, proteins capable of binding to these CT gene HLH consensus recognition sites were not restricted to CT-producing cells. We conclude that members of the HLH protein family, some expressed ubiquitously and some expressed or activated in a tissue-restricted fashion, may combine to enhance CT gene transcription in tumor cells of neuroendocrine derivation. Images PMID:1738589

Ball, D W; Compton, D; Nelkin, B D; Baylin, S B; de Bustros, A



Expression of the helix-loop-helix genes Id-1 and NSCL-1 during cerebellar development.  


Neurons throughout the central nervous system (CNS) undergo proliferation, migration, and differentiation during their histogenesis. Although numerous regulatory molecules are expressed in developing neurons, it is unknown whether most of these molecules have the same function throughout the CNS or play different roles in different neuronal populations. Previous studies have shown that Id-1 and NSCL-1 are expressed at high levels in the ventricular and subependymal zones, respectively, of the embryonic brain. In the present study, the expression of Id-1 and NSCL-1 was further investigated during postnatal development of the cerebellum. By Northern blot hybridization analysis, the expression levels of Id-1 and NSCL-1 mRNA were developmentally regulated in the cerebellum, with the highest mRNA levels coinciding with the time of maximal granule cell histogenesis. By in situ hybridization, NSCL-1 mRNA was found in the premigratory zone of the external granule layer (EGL), a structure developmentally analogous to the subependymal zone of the embryonic brain. In normal mice, Id-1 mRNA was found to be transiently expressed in the upper internal granule layer (IGL), a population of cells that recently completed their migration from the EGL. In the mouse mutant weaver, Id mRNA was only seen in granule cells that have reached their normal positions in the IGL. No Id-1 hybridization signal was observed in the large numbers of granule cells remaining in the EGL of weaver mice, indicating that Id-1 expression is controlled by spatial cues. The lack of Id-1 expression in ectopic weaver granule cells is compatible with previous suggestions of arrested differentiation. These results support the idea that transcriptional regulators of the helix-loop-helix gene family play important roles in neuronal development, exhibiting region-specific expression and function. PMID:8989525

Duncan, M K; Bordas, L; Dicicco-Bloom, E; Chada, K K



Phylogenetic Analysis of Plant Basic Helix-Loop-Helix Proteins Michael J. Buck, William R. Atchley  

E-print Network

the split of animals and plants, but appear to function in `plant-specific' or `animal-specific' pro- cesses sequenced Arabidopsis thali- ana genome and 131 bHLH genes in the rice genome. Here we report a phylogenetic


Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen Induces Expression of the Helix-Loop-Helix Protein Id-1 in Human Endothelial Cells  

PubMed Central

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) (also known as human herpesvirus 8) is a gamma-2 herpesvirus believed to be the etiologic agent responsible for KS. The pathogenesis of this potentially life-threatening neoplasm is complex and unclear, and it is currently unknown how KSHV causes KS. Id (named for inhibitor of DNA binding or inhibitor of differentiation) proteins were identified in 1990 and found to be naturally occurring dominant-negative inhibitors of basic helix-loop-helix transcription factors. Id-1, the most well-studied member of this family, has since been shown to play a key role in several biological systems including cellular differentiation, cell cycle regulation, and tumorigenesis. In this report, we demonstrate that Id-1 is expressed at high levels in KS tumor cells both in vitro and in vivo but is expressed at relatively modest levels in endothelial cells (ECs), the likely precursor of the KS tumor cell. Infection of precursor cells with KSHV may be responsible for this enhanced expression, as KSHV infection induced Id-1 27-fold in ECs under our experimental conditions. Furthermore, we demonstrate that the KSHV-encoded latency-associated nuclear antigen (LANA) protein appears to be involved. Expression of LANA in ECs resulted in Id-1 induction that was almost identical to the induction seen with KSHV-infected ECs. These results demonstrate the expression of Id-1 in KS tumor cells and indicate the KSHV LANA protein may be, at least in part, responsible. This may be an important mechanism by which KSHV allows KS tumor cells to escape normal cell cycle regulation and enhances their proliferation. PMID:12719589

Tang, Jun; Gordon, Gabriel M.; Müller, Maike G.; Dahiya, Madhu; Foreman, Kimberly E.



cDNA array analysis of pineal gene expression reveals circadian rhythmicity of the dominant negative helix-loop-helix protein-encoding gene, Id-1.  


The pineal gland is a major output of the endogenous vertebrate circadian clock, with melatonin serving as the output signal. In many species, elevated nocturnal melatonin production is associated with changes in pineal gene expression. In the current study, cDNA array analysis was used in an attempt to identify additional genes that exhibit day/night differential expression in the rat pineal gland. This revealed 38 candidate genes, including Id-1 (inhibitor of DNA binding and differentiation). Id-1 encodes a helix-loop-helix (HLH) protein that lacks a basic DNA binding domain and could affect pineal physiology via a dominant negative trans-acting regulatory activity. For this reason Id-1 was selected for further analysis. Id-1 was expressed in a major population of pineal cells and the Id-1 protein was associated with a nuclear complex. The levels of Id-1 mRNA and protein exhibit approximately six-fold day/night rhythms. In contrast, the related genes Id-2 and Id-3 do not exhibit marked day/night differences in pineal expression. Rhythmic Id-1 expression is primarily limited to a C-terminally extended splice variant of Id-1, which would restrict the functional output of the rhythm to protein binding partners of this isoform of Id-1. Our findings add to the body of evidence indicating that transcriptional regulators play a role in neuroendocrine rhythms, and extend this by introducing the concept of a dominant negative HLH involvement. The rhythm in Id-1 in the pineal gland provides an experimental opportunity to identify Id-1-binding partners which may also be involved in Id-1 activity in other functional contexts. PMID:11849369

Humphries, A; Klein, D; Baler, R; Carter, D A



The E2A and tal-1 helix-loop-helix proteins associate in vivo and are modulated by Id proteins during interleukin 6-induced myeloid differentiation.  

PubMed Central

The immunoglobulin enhancer-binding proteins, E12 and E47, encoded by the E2A gene belong to the basic helix-loop-helix (bHLH) family of regulatory proteins and act as transcriptional activators. In addition to their critical role in B-lymphocyte development, the E12 and E47 proteins have been implicated in the induction of myogenesis as heterodimeric partners of myogenic bHLH proteins, MyoD and myogenin. Here we demonstrate that the E2A proteins form heterodimers with the bHLH oncoprotein tal-1 in myeloid and erythroid cells and that these heterodimers specifically bind to the CANNTG DNA motif. Heterodimerization with tal-1 represses transactivation by E47 and could function to prevent the expression of immunoglobulin genes in cells other than B lymphocytes. DNA binding by E2A-tal-1 heterodimers in the M1 mouse myeloid cell line is abrogated upon terminal macrophage differentiation induced by the cytokine interleukin 6. The loss of E2A-tal-1 DNA binding is correlated with elevated expression of mRNA encoding the dominant negative HLH proteins, Id1 and particularly Id2. Moreover, recombinant Id proteins inhibit the E2A-tal-1-specific DNA binding activity from undifferentiated M1 cells. These results suggest that E2A-tal-1 heterodimers may play a role in preventing terminal differentiation in the myeloid lineage and provide a possible explanation for oncogenic transformation induced by ectopic tal-1 expression in acute T-cell lymphoblastic leukemias. Images PMID:8016095

Voronova, A F; Lee, F



Id-related genes encoding helix-loop-helix proteins are required for G1 progression and are repressed in senescent human fibroblasts.  


Three complete cDNA clones encoding Id-related helix-loop-helix (HLH) proteins lacking a basic region were isolated from a pcD2 cDNA expression library prepared from TIG-3 human diploid fibroblasts (HDF). Of these cDNAs (Id-1H, Id-1H', and Id-2H), two (Id-1H and Id-1H') appeared to be derived by alternative RNA splicing. Id-1H and Id-2H seem to be human homologues of mouse Id-1 and Id-2, respectively, and have potential to encode 154 and 135 amino acid proteins. The Id-1H and Id-2H mRNAs were barely detectable in quiescent early passage HDF; serum coordinately induced both mRNAs, with two peaks of expression, in early and late in G1. Antisense oligomers complementary to Id-1H and Id-2H mRNA prevented early passage HDF from entering the S phase of the cell cycle. The treatment of serum-stimulated early passage cells with the antisense Id-1H oligomer completely abolished Id-1H. In senescent cells, serum barely induced the Id-1H and Id-2H mRNAs, although the levels of c-myc expression induced were similar in early passage and senescent cells. The expression levels of these Id genes vary among immortal human cell lines. Both genes were overexpressed in VA4 SV40-transformed lung fibroblasts and EJ-1 bladder carcinoma cells, while these genes were expressed at a very low level in SVts8 cells derived from SV40 tsA-transformed TIG-3 cells. SVts8 cells may acquire some function redundant to Id proteins. HT1080 fibrosarcoma cells expressed the Id-1H gene but not the Id-2H gene, suggesting these Id genes may subserve redundant functions. PMID:8294468

Hara, E; Yamaguchi, T; Nojima, H; Ide, T; Campisi, J; Okayama, H; Oda, K



A novel initiator regulates expression of the nontissue-specific helix-loop-helix gene ME1.  

PubMed Central

The mouse ME1 gene (HEB, REB and GE1, homologues in human, rat and chick, respectively) is a member of the nontissue-specific helix-loop-helix (HLH) gene family that includes E2A, E2-2 and Drosophila daughterless. We have examined the factors that control ME1 gene expression. ME1 is a single copy gene that spans > or = 150 kb of DNA and contains > 10 exons. Transcription was directed by an unusual initiator element that contained a 13 bp poly d(A) tract flanked by palindromic and inverted repeat sequences. Both RNase protection and primer extension analyses mapped the ME1 transcriptional start site to the center of the 13 bp poly d(A) tract. The ME1 initiator and its proximal sequences were required for promoter activity, supported basal levels of transcription, and contributed to cell type-specific gene expression. Other cis-elements utilized by the TATA-less ME1 promoter included a cluster of Sp1 response elements, E-boxes and a strong repressor. Collectively, our results suggest that the ME1 initiator and other cis-elements in the proximal promoter play an important role in regulating ME1 gene expression. Images PMID:7784173

Shain, D H; Neuman, T; Zuber, M X



Molecular cloning and chromosomal localization of the murine homolog of the human helix-loop-helix gene SCL  

SciTech Connect

The human SCL gene is a member of the family of genes that encode the helix-loop-helix (HLH) class of DNA-binding proteins. A murine SCL cDNA was isolated from a normal macrophage cDNA library by using HLH-specific oligonucleotides as hybridiazation probes. The coding region is 987 base pairs and encodes a predicted protein of 34 kDa. The nucleotide sequence of the coding region shows 88% identity to the human SCL gene, and the amino acid sequence is 94% identical. The LHL motif and upstream hydrophilic region are entirely conserved in the murine and human proteins. The identity between the mouse and human sequences was less marked in the 5{prime} and 3{prime} untranslated regions. Two murine SCL transcripts that differ in the 3{prime} noncoding region have been detected in fetal liver and various cell lines. Variation was also observed in the 5{prime} untranslated region. Interestingly, immediately downstream of the protein-termination codon, both the human SCL sequence and the murine homolog share an E-box element - the suggested target site for DNA binding of HLH proteins. The murine SCL homolog was mapped to the central part of chromosome 4.

Begley, C.G.; Visvader, J.; Green, A.R.; Metcalf, D.; Gough, N.M. (Royal Melbourne Hospital, Victoria (Australia)); Aplan, P.D.; Kirsch, I.R. (National Cancer Inst., Bethesda, MD (United States))



Intricate gene regulatory networks of helix-loop-helix (HLH) proteins support regulation of bone-tissue related genes during osteoblast differentiation  

Microsoft Academic Search

Helix-loop-helix (HLH) transcription factors are key regulators of neurogenesis, myogenesis and osteogenesis. Here the relative contributions of multiple classes of HLH factors to the expression of bone related genes during osteoblast maturation were compared. We examined the expression of a panel of HLH proteins (e.g., Twist1\\/2, USF1\\/2, c-Myc, Id1 approximately 4, E12\\/47, Stra13) and one Zn finger protein (Snail which

Ying Zhang; Mohammad Q. Hassan; Zhao-Yong Li; Janet L. Stein; Jane B. Lian; Andre J. Van Wijnen; Gary S. Stein



Anthocyanin1 of petunia encodes a basic helix-loop-helix protein that directly activates transcription of structural anthocyanin genes  

Microsoft Academic Search

The petunia loci anthocyanin1 ( an1 ), an2 , an4 , and an11 are required for the transcription of anthocyanin biosynthetic genes in floral organs. The an2 and an11 loci were recently cloned and shown to encode a MYB-domain transcriptional activator and a cytosolic WD40 protein, respectively. Here, we report the isolation of an1 by transposon tagging. an1 encodes a

Cornelis Spelt; Francesca Quattrocchio; Joseph N. M. Mol; Ronald Koes




Technology Transfer Automated Retrieval System (TEKTRAN)

The phytochrome (phy) family of sensory photoreceptors (phyA to phyE) in Arabidopsis thaliana control plant developmental transitions in response to informational light signals throughout the life cycle. The photoactivated conformer of the photoreceptor Pfr has been shown to translocate into the nuc...


Mmot1, a new helix-loop-helix transcription factor gene displaying a sharp expression boundary in the embryonic mouse brain.  


Several genetic factors have been proven to contribute to the specification of the metencephalic-mesencephalic territory, a process that sets the developmental foundation for prospective morphogenesis of the cerebellum and mesencephalon. However, evidence stemming from genetic and developmental studies performed in man and various model organisms suggests the contribution of many additional factors in determining the fine subdivision and differentiation of these central nervous system regions. In man, the cerebellar ataxias/aplasias represent a large and heterogeneous family of genetic disorders. Here, we describe the identification by differential screening and the characterization of Mmot1, a new gene encoding a DNA-binding protein strikingly similar to the helix-loop-helix factor Ebf/Olf1. Throughout midgestation embryogenesis, Mmot1 is expressed at high levels in the metencephalon, mesencephalon, and sensory neurons of the nasal cavity. In vitro DNA binding data suggest some functional equivalence of Mmot1 and Ebf/Olf1, possibly accounting for the reported lack of olfactory or neural defects in Ebf-/- knockout mutants. The isolation of Mmot1 and of an additional homolog in the mouse genome defines a novel, phylogenetically conserved mammalian family of transcription factor genes of potential relevance in studies of neural development and its aberrations. PMID:9211912

Malgaretti, N; Pozzoli, O; Bosetti, A; Corradi, A; Ciarmatori, S; Panigada, M; Bianchi, M E; Martinez, S; Consalez, G G



Expression of the helix-loop-helix protein inhibitor of DNA binding-1 (ID-1) is activated by all-trans retinoic acid in normal human keratinocytes  

SciTech Connect

The ID (inhibitor of differentiation or DNA binding) helix-loop-helix proteins are important mediators of cellular differentiation and proliferation in a variety of cell types through regulation of gene expression. Overexpression of the ID proteins in normal human keratinocytes results in extension of culture lifespan, indicating that these proteins are important for epidermal differentiation. Our hypothesis is that the ID proteins are targets of the retinoic acid signaling pathway in keratinocytes. Retinoids, vitamin A analogues, are powerful regulators of cell growth and differentiation and are widely used in the prevention and treatment of a variety of cancers in humans. Furthermore, retinoic acid is necessary for the maintenance of epithelial differentiation and demonstrates an inhibitory action on skin carcinogenesis. We examined the effect of all-trans retinoic acid on expression of ID-1, -2, -3, and -4 in normal human keratinocytes and found that exposure of these cells to all-trans retinoic acid causes an increase in both ID-1 and ID-3 gene expression. Furthermore, our data show that this increase is mediated by increased transcription involving several cis-acting elements in the distal portion of the promoter, including a CREB-binding site, an Egr1 element, and an YY1 site. These data demonstrate that the ID proteins are direct targets of the retinoic acid signaling pathway. Given the importance of the ID proteins to epidermal differentiation, these results suggest that IDs may be mediating some of the effects of all-trans retinoic acid in normal human keratinocytes.

Villano, C.M. [Department of Biochemistry and Microbiology, 76 Lipman Drive, Rutgers, State University of NJ, New Brunswick, NJ 08901 (United States); White, L.A. [Department of Biochemistry and Microbiology, 76 Lipman Drive, Rutgers, State University of NJ, New Brunswick, NJ 08901 (United States)]. E-mail:



Expression from the murine p53 promoter is mediated by factor binding to a downstream helix-loop-helix recognition motif.  

PubMed Central

Expression of the p53 gene plays an important role in the regulation of cellular proliferation and malignant transformation. Overexpression of mutant forms of p53 is in fact a common feature of many transformed cells. Studies dealing with the transcriptional regulatory regions of the p53 gene indicate that, unlike most promoters transcribed by RNA polymerase II, the p53 promoter contains no TATA-like sequence upstream of the transcription start site. Here we demonstrate that the murine p53 promoter contains a cis-acting element that maps downstream to the transcription initiation site. The integrity of this element is required for high-level expression from the promoter in transformed cells. By DNase I protection and mobility-shift analysis, we show that a nuclear factor binds to this downstream element through the consensus recognition sequence for the helix-loop-helix (HLH)-containing proteins of the myc/MyoD family of transcriptional regulators. We propose that the activity of one or more members of this family of transcription factors is an important determinant in the expression of p53 and that at least one level of p53 overexpression in transformed cells may thus be due to aberrant expression of the relevant factor(s). Furthermore, the possibility that the regulation of expression of p53 occurs, in part, by means of a potential HLH-containing factor provides a possible mechanism for the suppression of proliferation by the MyoD family of transcriptional regulators. Images PMID:1851994

Ronen, D; Rotter, V; Reisman, D



A cell-penetrating peptide suppresses the hypoxia inducible factor-1 function by binding to the helix-loop-helix domain of the aryl hydrocarbon receptor nuclear translocator  

PubMed Central

The heterodimeric hypoxia inducible factor-1 (HIF-1) complex is composed of the hypoxia inducible factor-1 alpha (HIF-1?) and the aryl hydrocarbon receptor nuclear translocator (ARNT). Activation of the HIF-1 function is essential for tumor growth and metastasis. We previously showed that transfection of a plasmid containing an ARNT-interacting peptide (Ainp1) cDNA suppresses the HIF-1 signaling in Hep3B cells. Here we generated TAT fusion of the Ainp1 peptide (6His-TAT-Ainp1) to determine whether and how the Ainp1 peptide suppresses the HIF-1 function. The bacterially expressed 6His-TAT-Ainp1 was purified under denatured condition and then refolded by limited dialysis. The refolded 6His-TAT-Ainp1 interacts with the helix-loop-helix (HLH) domain of ARNT in a similar fashion as the native 6His-Ainp1. 6His-TAT-Ainp1 colocalizes with ARNT in the nucleus of HeLa and Hep3B cells after protein transduction. The transduced protein reaches the maximum intracellular levels within 2 h while remains detectable up to 96 h in HeLa cells. At 2 µM concentration, 6His-TAT-Ainp1 is not cytotoxic in HeLa cells but suppresses the cobalt chloride-activated, hypoxia responsive enhancer-driven luciferase expression in a dose-dependent manner. In addition, it decreases the cobalt chloride-dependent induction of the HIF-1 target genes at both the message (vascular endothelial growth factor and aldolase C) and protein (carbonic anhydrase IX and glucose transporter 1) levels. The protein levels of HIF-1? and ARNT are not altered in the presence of 6His-TAT-Ainp1. In summary, we provided evidence to support that the Ainp1 peptide directly suppresses the HIF-1 function by interacting with the ARNT HLH domain, and in turn interfering with the heterodimerization of HIF-1? and ARNT. PMID:23454269

Wang, Yu; Thompson, John D.; Chan, William K.



The TT8 Gene Encodes a Basic Helix-Loop-Helix Domain Protein Required for Expression of DFR and BAN Genes in Arabidopsis Siliques  

Microsoft Academic Search

The TRANSPARENT TESTA8 ( TT8 ) locus is involved in the regulation of flavonoid biosynthesis in Arabidopsis. The tt8-3 allele was isolated from a T-DNA-mutagenized Arabidopsis collection and found to be tagged by an integrative mole- cule, thus permitting the cloning and sequencing of the TT8 gene. TT8 identity was confirmed by complementation of tt8-3 and sequence analysis of an

Nathalie Nesi; Isabelle Debeaujon; Clarisse Jond; Georges Pelletier; Michel Caboche; Loïc Lepiniec



Human Variants in the Neuronal Basic Helix-Loop-Helix/Per-Arnt-Sim (bHLH/PAS) Transcription Factor Complex NPAS4/ARNT2 Disrupt Function  

PubMed Central

Neuronal Per-Arnt-Sim homology (PAS) Factor 4 (NPAS4) is a neuronal activity-dependent transcription factor which heterodimerises with ARNT2 to regulate genes involved in inhibitory synapse formation. NPAS4 functions to maintain excitatory/inhibitory balance in neurons, while mouse models have shown it to play roles in memory formation, social interaction and neurodegeneration. NPAS4 has therefore been implicated in a number of neuropsychiatric or neurodegenerative diseases which are underpinned by defects in excitatory/inhibitory balance. Here we have explored a broad set of non-synonymous human variants in NPAS4 and ARNT2 for disruption of NPAS4 function. We found two variants in NPAS4 (F147S and E257K) and two variants in ARNT2 (R46W and R107H) which significantly reduced transcriptional activity of the heterodimer on a luciferase reporter gene. Furthermore, we found that NPAS4.F147S was unable to activate expression of the NPAS4 target gene BDNF due to reduced dimerisation with ARNT2. Homology modelling predicts F147 in NPAS4 to lie at the dimer interface, where it appears to directly contribute to protein/protein interaction. We also found that reduced transcriptional activation by ARNT2 R46W was due to disruption of nuclear localisation. These results provide insight into the mechanisms of NPAS4/ARNT dimerisation and transcriptional activation and have potential implications for cognitive phenotypic variation and diseases such as autism, schizophrenia and dementia. PMID:24465693

Bersten, David C.; Bruning, John B.; Peet, Daniel J.; Whitelaw, Murray L.



Responses of a Triple Mutant Defective in Three Iron Deficiency-Induced BASIC HELIX-LOOP-HELIX Genes of the Subgroup Ib(2) to Iron Deficiency and Salicylic Acid  

PubMed Central

Plants are sessile organisms that adapt to external stress by inducing molecular and physiological responses that serve to better cope with the adverse growth condition. Upon low supply of the micronutrient iron, plants actively increase the acquisition of soil iron into the root and its mobilization from internal stores. The subgroup Ib(2) BHLH genes function as regulators in this response, however their concrete functions are not fully understood. Here, we analyzed a triple loss of function mutant of BHLH39, BHLH100 and BHLH101 (3xbhlh mutant). We found that this mutant did not have any iron uptake phenotype if iron was provided. However, under iron deficiency the mutant displayed a more severe leaf chlorosis than the wild type. Microarray-based transcriptome analysis revealed that this mutant phenotype resulted in the mis-regulation of 198 genes, out of which only 15% were associated with iron deficiency regulation itself. A detailed analysis revealed potential targets of the bHLH transcription factors as well as genes reflecting an exaggerated iron deficiency response phenotype. Since the BHLH genes of this subgroup have been brought into the context of the plant hormone salicylic acid, we investigated whether the 3xbhlh mutant might have been affected by this plant signaling molecule. Although a very high number of genes responded to SA, also in a differential manner between mutant and wild type, we did not find any indication for an association of the BHLH gene functions in SA responses upon iron deficiency. In summary, our study indicates that the bHLH subgroup Ib(2) transcription factors do not only act in iron acquisition into roots but in other aspects of the adaptation to iron deficiency in roots and leaves. PMID:24919188

Maurer, Felix; Naranjo Arcos, Maria Augusta; Bauer, Petra



Biochemical and Phosphoproteomic Analysis of the Helix-Loop-Helix Protein E47  

PubMed Central

Numerous in vitro as well as genetic studies have demonstrated that the activities of the E2A proteins are regulated at multiple levels, including modulation of DNA binding by the Id proteins, association with the transcriptional modulators p300 and ETO, and posttranslational modifications. Here, we use affinity purification of tagged E47 combined with mass spectrometry in order to show that E47 interacts with the entire ensemble of Id proteins, namely, Id1, Id2, Id3, and Id4. Furthermore, we find that the lysine-specific histone demethylase 1 (LSD1), the protein arginine N-methyltransferase 5 (PRMT5), the corepressor CoREST, and the chaperones of the 14-3-3 family associate with affinity-purified E47. We also identify a spectrum of amino acid residues in E47 that are phosphorylated, including an AKT substrate site. We did, however, find that mutation of the identified AKT substrate site by itself did not perturb B cell development. In sum, these studies show that the entire ensemble of Id proteins has the ability to interact with E47, identify factors that associate with E47, and reveal a spectrum of phosphorylated residues in E47, including an AKT substrate site. PMID:22354994

Teachenor, Robert; Wright, Lilyan Y. T.; Shen, Zhouxin; Briggs, Steven P.; Murre, Cornelis



The helix-loop-helix protein Id1 controls stem cell proliferation during regenerative neurogenesis in the adult zebrafish telencephalon.  


The teleost brain has the remarkable ability to generate new neurons and to repair injuries during adult life stages. Maintaining life-long neurogenesis requires careful management of neural stem cell pools. In a genome-wide expression screen for transcription regulators (TRs), the id1 gene, encoding a negative regulator of E-proteins, was found to be up-regulated in response to injury. id1 expression was mapped to quiescent type I neural stem cells in the adult telencephalic stem cell niche. Gain and loss of id1 function in vivo demonstrated that Id1 promotes stem cell quiescence. The increased id1 expression observed in neural stem cells in response to injury appeared independent of inflammatory signals, suggesting multiple antagonistic pathways in the regulation of reactive neurogenesis. Together, we propose that Id1 acts to maintain the neural stem cell pool by counteracting neurogenesis-promoting signals. Stem Cells 2014. PMID:25376791

Rodriguez Viales, Rebecca; Diotel, Nicolas; Ferg, Marco; Armant, Olivier; Eich, Julia; Alunni, Alessandro; März, Martin; Bally-Cuif, Laure; Rastegar, Sepand; Strähle, Uwe



Identifying Novel Helix-Loop-Helix Genes in "Caenorhabditis elegans" through a Classroom Demonstration of Functional Genomics  

ERIC Educational Resources Information Center

A 14-week, undergraduate-level Genetics and Population Biology course at Morgan State University was modified to include a demonstration of functional genomics in the research laboratory. Students performed a rudimentary sequence analysis of the "Caenorhabditis elegans" genome and further characterized three sequences that were predicted to encode…

Griffin, Vernetta; McMiller, Tracee; Jones, Erika; Johnson, Casonya M.



Development . Author manuscript Intermuscular tendons are essential for the development of vertebrate  

E-print Network

is essential for the correct morphogenesis of the stomach. MESH Keywords Animals ; Animals, Genetically Modified ; Avian Proteins ; antagonists & inhibitors ; genetics ; metabolism ; Base Sequence ; Basic Helix-Loop-Helix Transcription Factors ; antagonists & inhibitors ; genetics ; metabolism ; Cell Differentiation ; Chick Embryo

Boyer, Edmond


Transcriptional regulation of neurodevelopmental and metabolic pathways by the psychiatric illness candidate gene NPAS3   

E-print Network

The basic helix-loop-helix PAS domain transcription factor gene NPAS3 is a risk factor for psychiatric disorders. A knockout mouse model also exhibits behavioural and adult neurogenesis deficits consistent with human ...

Sha, Li



Protein- mediated enamel mineralization  

PubMed Central

Enamel is a hard nanocomposite bioceramic with significant resilience that protects the mammalian tooth from external physical and chemical damages. The remarkable mechanical properties of enamel are associated with its hierarchical structural organization and its thorough connection with underlying dentin. This dynamic mineralizing system offers scientists a wealth of information that allows the study of basic principals of organic matrix-mediated biomineralization and can potentially be utilized in the fields of material science and engineering for development and design of biomimetic materials. This chapter will provide a brief overview of enamel hierarchical structure and properties as well as the process and stages of amelogenesis. Particular emphasis is given to current knowledge of extracellular matrix protein and proteinases, and the structural chemistry of the matrix components and their putative functions. The chapter will conclude by discussing the potential of enamel for regrowth. PMID:22652761

Moradian-Oldak, Janet



Metamorphic proteins mediate evolutionary transitions of structure  

E-print Network

Metamorphic proteins mediate evolutionary transitions of structure Itamar Yadida , Noam. Such metamorphic proteins provide a means of facilitating the evolution of new folds and ar- chitectures. However, because natural folds emerged at the early stages of evolution, the potential role of metamorphic

Tawfik, Dan S.


Mechanistic duality of transcription factor function in phytochrome signaling  

Technology Transfer Automated Retrieval System (TEKTRAN)

The phytochrome (phy) family of sensory photoreceptors (phyA–E in Arabidopsis) elicit changes in gene expression after light-induced migration to the nucleus, where they interact with basic helix–loop–helix transcription factors, such as phytochrome-interacting factor 3 (PIF3). The mechanism by whic...


Of worms and men: HLH-30 and TFEB regulate tolerance to infection.  


In this issue of Immunity, Visvikis et al. (2014) use the model host Caenorhabditis elegans to discover a role in innate immunity for the basic helix-loop-helix transcription factor, HLH-30. The finding inspires study of the mammalian ortholog TFEB, in which a similar role in immune response is ascertained. PMID:24950206

Tiller, George R; Garsin, Danielle A



The role of dimerisation and nuclear transport in the Hes1 gene regulatory network  

E-print Network

The role of dimerisation and nuclear transport in the Hes1 gene regulatory network Marc Sturrock a of the family of basic helix-loop-helix transcription factors and the Hes1 gene regulatory network (GRN) may. E-mail address: 1. Introduction Gene regulatory networks (GRNs) lie at the core

Petzold, Linda R.


In cancer cells, monoallelic expression of oncogenes can occur through a variety of mechanisms including chromo-  

E-print Network

Reports In cancer cells, monoallelic expression of oncogenes can occur through a variety in overexpression of TAL1, an oncogene coding for a basic helix-loop-helix transcription factor, by mediating fu at oncogenes critical for the malig- nant cell state (11­17). The super- enhancer encompassing TAL1 in Jurkat

Napp, Nils


Analysis of the Arabidopsis NAC gene superfamily in plant development  

E-print Network

proteins belong to different classes or families. The three largest families of transcription factors in Arabidopsis are AP2/EREBP (APETALA2/ethylene responsive element binding protein), MYB-(R1)R2R3, and bHLH (basic helix- loop-helix). There are many...

Alvarado Chavez, Veria Ysabel



Cannabidiol as a novel inhibitor of Id1 gene expression in aggressive breast cancer cells  

Microsoft Academic Search

Invasion and metastasis of aggressive breast cancer cells is the final and fatal step during cancer progression, and is the least understood genetically. Clinically, there are still limited therapeutic interventions for aggressive and meta- static breast cancers available. Clearly, effective and non- toxic therapies are urgently required. Id-1, an inhibitor of basic helix-loop-helix transcription factors, has recently been shown to

Sean D. McAllister; Rigel T. Christian; Maxx P. Horowitz; Amaia Garcia; Pierre-Yves Desprez



HAND2 Mutation Detection in Tricuspid Atresia Patients. Elijah H. Barry1 2  

E-print Network

HAND2 Mutation Detection in Tricuspid Atresia Patients. Elijah H. Barry1 2 , Nathan VanDusen1 , Dr of transcription factor Hand2 function within a population of cells that line the inside of the heart (the endocardium) results in a TA phenotype. Hand2 is a protein that belongs to the basic helix-loop-helix family

Zhou, Yaoqi

83 february 2001 volume 2 no 2 nature immunology Gretchen Bain1  

E-print Network

/or proliferation in a wide variety of cell types, including developing thymocytes.The basic helix- loop-helix (bHLH) proteins E12 and E47 and an inhibitor HLH protein, Id3, play key roles in thymocyte differentiation. We connect the ERK MAPK cascade and HLH proteins in a linear pathway. 1 Department of Biology, 0366

Hedrick, Stephen M.


MOLECULAR AND CELLULAR BIOLOGY, 0270-7306/98/$04.00 0  

E-print Network

Members of the helix-loop-helix (HLH) family of Id proteins have demonstrated roles in the regulation of differentiation and cell proliferation. Id proteins inhibit differentiation by HLH-mediated heterodimerization with basic HLH transcription factors. This blocks their sequence-specific binding to DNA and activation


MOLECULAR AND CELLULAR BIOLOGY, Oct. 2002, p. 73377350 Vol. 22, No. 20 0270-7306/02/$04.00 0 DOI: 10.1128/MCB.22.20.73377350.2002  

E-print Network

for controlling early B-cell development (1, 70, 71). E2A belongs to the helix-loop-helix (HLH) class (E12, E47, and E2-5), which differ either at their N-terminal regions or within the basic HLH (bHLH

McIntosh, Lawrence P.


Proc. Natl. Acad. Sci. USA Vol. 94, pp. 1309913104, November 1997  

E-print Network

bear a helix-loop-helix (HLH) dimerization domain, we investigated their potential pairwise that the seven E(spl) basic HLH proteins can form homo- and heterodimers inter-se with distinct preferences. We(spl) family. Hairy displays no interactions with any of the HLH proteins tested. It does interact with the non-HLH

Parkhurst, Susan



Technology Transfer Automated Retrieval System (TEKTRAN)

The ID (Inhibitor of DNA Binding/Differentiation) proteins represent a family of dominant negative regulators of the basic helix-loop-helix (bHLH) transcription factors whose activities result in delayed cell differentiation and prolonged proliferation. We have previously identified the rainbow trou...


Determinants of Myogenic Specificity within MyoD Are Required for Noncanonical E Box Binding  

Microsoft Academic Search

The MyoD family of basic helix-loop-helix (bHLH) transcription factors has the remarkable ability to induce myogenesis in vitro and in vivo. This myogenic specificity has been mapped to two amino acids in the basic domain, an alanine and threonine, referred to as the myogenic code. These essential determinants of myogenic specificity are conserved in all MyoD family members from worms

Analeah B. Heidt; Anabel Rojas; Ian S. Harris; Brian L. Black



Protein Mediators of Sterol Transport Across Intestinal Brush Border Membrane  

PubMed Central

Dysregulation of cholesterol balance contributes significantly to atherosclerotic cardiovascular disease (ASCVD), the leading cause of death in the United States. The intestine has the unique capability to act as a gatekeeper for entry of cholesterol into the body, and inhibition of intestinal cholesterol absorption is now widely regarded as an attractive non-statin therapeutic strategy for ASCVD prevention. In this chapter we discuss the current state of knowledge regarding sterol transport across the intestinal brush border membrane. The purpose of this work is to summarize substantial progress made in the last decade in regards to protein-mediated sterol trafficking, and to discuss this in the context of human disease. PMID:20213550

Brown, J. Mark; Yu, Liqing



The cellular Pax-Hox-helix connection.  


Basic helix-loop-helix (bHLH) transcription factors are important regulators of lineage determination during embryogenesis. Initial experiments in Drosophila showed that early neural selection and specification are dependent on atonal (ato) and members of the achaete-scute complex (as-c). In mammals, transcription factors homologous to as-c and ato are causally involved during development of organs throughout the body. Development of subsets of lineages in intestine, stomach, pancreas, lung, thyroid and placenta have been shown to be regulated by members of the as-c and ato families. These functional studies show that an individual bHLH transcription factor can regulate multiple developmental processes throughout the mammalian body, which implicates that extant as-c and ato transcription factors play a distinct function dependent on their cellular context. Based on the synergistic activation of the insulin, POMC and Pax4 promotors by bHLH and homeobox (Hox) protein complexes, we hypothesize that the underlying cellular function-modulating factors include members of the Hox and paired box (Pax) multigene families. These examples indicate that unique combinations of bHLH and Hox proteins, mediated by protein-protein interactions, might be responsible for activating cell-specific sets of target genes. PMID:14522074

Westerman, Bart A; Murre, Cornelis; Oudejans, Cees B M



Gene transfer of antisense hypoxia inducible factor-1 ? enhances the therapeutic efficacy of cancer immunotherapy  

Microsoft Academic Search

Solid tumors meet their demands for nascent blood vessels and increased glycolysis, to combat hypoxia, by activating multiple genes involved in angiogenesis and glucose metabolism. Hypoxia inducible factor-1 (HIF-1) is a constitutively expressed basic helix–loop–helix transcription factor, formed by the assembly of HIF-1? and HIF-1? (Arnt), that is stablized in response to hypoxia, and rapidly degraded under normoxic conditions. It

X Sun; J R Kanwar; E Leung; K Lehnert; D Wang; G W Krissansen



Math5 expression and function in the central auditory system  

Microsoft Academic Search

The basic helix–loop–helix (bHLH) transcription factor Math5 (Atoh7) is required for retinal ganglion cell (RGC) and optic nerve development. Using Math5-lacZ knockout mice, we have identified an additional expression domain for Math5 outside the eye, in functionally connected structures of the central auditory system. In the adult hindbrain, the cytoplasmic Math5-lacZ reporter is expressed within the ventral cochlear nucleus (VCN),

Sara M. Saul; Joseph A. Brzezinski IV; Richard A. Altschuler; Susan E. Shore; Dellaney D. Rudolph; Lisa L. Kabara; Karin E. Halsey; Robert B. Hufnagel; Jianxun Zhou; David F. Dolan; Tom Glaser



Hairy Transcriptional Repression Targets and Cofactor Recruitment in Drosophila  

Microsoft Academic Search

Members of the widely conserved Hairy\\/Enhancer of split family of basic Helix-Loop-Helix repressors are essential for proper Drosophila and vertebrate development and are misregulated in many cancers. While a major step forward in understanding the molecular mechanism(s) surrounding Hairy-mediated repression was made with the identification of Groucho, Drosophila C-terminal binding protein (dCtBP), and Drosophila silent information regulator 2 (dSir2) as

Daniella Bianchi-Frias; Amir Orian; Jeffrey J Delrow; Julio Vazquez; Alicia E Rosales-Nieves; Susan M Parkhurst



Integrated Expression Profiling and Genome-Wide Analysis of ChREBP Targets Reveals the Dual Role for ChREBP in Glucose-Regulated Gene Expression  

Microsoft Academic Search

The carbohydrate response element binding protein (ChREBP), a basic helix-loop-helix\\/leucine zipper transcription factor, plays a critical role in the control of lipogenesis in the liver. To identify the direct targets of ChREBP on a genome-wide scale and provide more insight into the mechanism by which ChREBP regulates glucose-responsive gene expression, we performed chromatin immunoprecipitation-sequencing and gene expression analysis. We identified

Yun-Seung Jeong; Deokhoon Kim; Yong Seok Lee; Ha-Jung Kim; Jung-Youn Han; Seung-Soon Im; Hansook Kim Chong; Je-Keun Kwon; Yun-Ho Cho; Woo Kyung Kim; Timothy F. Osborne; Jay D. Horton; Hee-Sook Jun; Yong-Ho Ahn; Sung-Min Ahn; Ji-Young Cha



Glucocorticoid-enhanced expression of dioxin target genes through regulation of the rat aryl hydrocarbon receptor  

Microsoft Academic Search

The aryl hydrocarbon receptor (AhR) and glucocorticoid receptor (GR) are ligand-activated transcription factors and members of the basic helix-loop-helix Period-aryl hydrocarbon nuclear translocator-single minded and nuclear hormone receptor superfamilies, respectively. Besides their individual role as acti- vators of specific gene transcription, also interplay between both transcription factors can be an important mechanism of regula- tion. In this study, we report

Edwin Sonneveld; Arjen Jonas; Onno C. Meijer; Abraham Brouwer; Bart van der Burg



Isolation of a Regulatory Gene of Anthocyanin Biosynthesis in Tuberous Roots of Purple-Fleshed Sweet Potato  

Microsoft Academic Search

Many transcriptional factors harboring the R2R3-MYB domain, basic helix-loop-helix domain, or WD40 repeats have been identified in various plant species as regulators of flavonoid biosynthesis in flowers, seeds, and fruits. However, the regulatory elements of flavonoid biosynthesis in underground organs have not yet been elucidated. We isolated the novel MYB genesIbMYB1 andIbMYB2s from purple-fleshed sweet potato (Ipomoea batatas L. Lam.

Hironori Mano; Fumiaki Ogasawara; Kazuhito Sato; Hiromi Higo; Yuzo Minobe



Twist1 dimer selection regulates cranial suture patterning and fusion  

Microsoft Academic Search

Saethre-Chotzen syndrome is associated with haploinsufficiency of the basic-helix-loop- helix (bHLH) transcription factor TWIST1 and is characterized by premature closure of the cranial sutures, termed craniosynostosis; however, the mechanisms underlying this defect are unclear. Twist1 has been shown to play both positive and negative roles in mesenchymal specification and differentiation, and here we show that the activity of Twist1 is

Jeannette Connerney; Viktoria Andreeva; Yael Leshem; Christian Muentener; Miguel A. Mercado; Douglas B. Spicer



Transcriptionally Active Heterodimer Formation of an Arnt-like PAS Protein, Arnt3, with HIF-1a, HLF, and Clock  

Microsoft Academic Search

We isolated a cDNA clone encoding a polypeptide of 626 amino acids containing basic helix–loop–helix (bHLH) and PAS domains from a mouse cDNA library of P19 cells. This protein, termed Arnt3, showed the highest similarity to Arnt and Arnt2 in the bHLH and PAS regions. Arnt3 mRNA was expressed in brain, skeletal muscle, 13.5-day embryos, and P19 cells treated with

Sho Takahata; Kazuhiro Sogawa; Akira Kobayashi; Masatsugu Ema; Junsei Mimura; Nobuhiro Ozaki; Yoshiaki Fujii-Kuriyama



Inner Ear Sensory Epithelia Development and Regulation in Zebrafish  

E-print Network

). Equivalence groups are initially marked by expression of proneural genes. In Drosophila, proneural genes are required for specification of sensory organ precursors and formation of sensory organs (Brunet and Ghysen, 1999). Proneural genes encode basic... Helix-Loop-Helix (bHLH) transcription factors that have DNA binding and dimerization abilities. In Drosophila these proteins are divided into families with the achaete-scute gene family specifying external sensory bristles while the atonal (ato) gene...

Sweet, Elly Mae



Mitf and Tfe3: members of a b-HLH-ZIP transcription factor family essential for osteoclast development and function  

Microsoft Academic Search

The Microphthalmia-associated transcription factor (Mitf) is required for the proper development of several cell lineages including osteoclasts, melanocytes, retinal pigment epithelial cells, mast cells and natural killer cells. Mutations in Mitf in multiple organisms result in osteopetrosis due to defective osteoclast development. Mitf is a member of the basic\\/helix-loop-helix\\/leucine zipper (b-HLH-ZIP) transcription factor subfamily named MiT, which also includes Tfe3.

Christine L Hershey; David E Fisher



Multiple roles for the E\\/Daughterless ortholog HLH-2 during C. elegans gonadogenesis  

Microsoft Academic Search

HLH-2 is the Caenorhabditis elegans ortholog of the Drosophila Daughterless and mammalian E basic helix–loop–helix (bHLH) transcriptional activators that function during diverse events during animal development. HLH-2 has been implicated in cell fate specification in different neural lineages and in the LIN-12\\/Notch-mediated anchor cell (AC)\\/ventral uterine precursor cell (VU) decision in the somatic gonad. Here, we show that hlh-2 plays

Xantha Karp; Iva Greenwald




E-print Network

) are required for expression of the basic helix-loop-helix (bHLH) transcription factor Olig2 (Liu et al., 2003, respectively. These genes regulate glial expression of the C. elegans Olig1/2-related gene hlh-17. Using mls-2Is105 (hlh-17::GFP); LGIV: nsIs136 (ptr- 10::myrRFP), hlh-17 [ns204, ok487 (McMiller and Johnson, 2005

Shaham, Shai


Analysis of the Myc and Max Interaction Specificity with ? Repressor-HLH Domain Fusions  

Microsoft Academic Search

The basic helix-loop-helix domain (bHLH) is present in a large class of transcriptional regulators involved in developmental processes and oncogenesis. It determines DNA binding and specific homo- and heterodimeric protein associations, crucial for protein function. Myc and Max belong to a subset of HLH proteins, containing a leucine zipper (LZ) adjacent to the bHLH domain. They differ in dimerization and

Alessandra Marchetti; Marian Abril-Marti; Barbara Illi; Gianni Cesareni; Sergio Nasi



Normal and disease-related biological functions of Twist1 and underlying molecular mechanisms  

Microsoft Academic Search

This article reviews the molecular structure, expression pattern, physiological function, pathological roles and molecular mechanisms of Twist1 in development, genetic disease and cancer. Twist1 is a basic helix-loop-helix domain-containing transcription factor. It forms homo- or hetero-dimers in order to bind the Nde1 E-box element and activate or repress its target genes. During development, Twist1 is essential for mesoderm specification and

Qian Qin; Young Xu; Tao He; Chunlin Qin; Jianming Xu



Cloning and molecular analysis of paraxis: A {\\\\it trans\\\\\\/}-acting factor required for somite maturation  

Microsoft Academic Search

During vertebrate embryogenesis, cells from the paraxial mesoderm coalesce in a rostral-to-caudal progression to form the somites. Subsequent compartmentalization of the somites yields the sclerotome, myotome and dermatome, which give rise to the axial skeleton, axial musculature, and dermis, respectively. Recently, we cloned a novel basic-Helix-Loop-Helix (bHLH) protein, called scleraxis, which is expressed in the sclerotome, in mesenchymal precursors of

Robert Marshall Burgess



The bHLH Transcription Factor Olig2 Promotes Oligodendrocyte Differentiation in Collaboration with Nkx2.2  

Microsoft Academic Search

Olig2, a basic helix-loop-helix (bHLH) transcription factor, is expressed in a restricted domain of the spinal cord ventricular zone that sequentially generates motoneurons and oligodendrocytes. Just prior to oligo-dendrocyte precursor formation, the domains of Olig2 and Nkx2.2 expression switch from being mutually exclusive to overlapping, and Neurogenins1 and 2 are extinguished within this region. Coexpression of Olig2 with Nkx2.2 in

Qiao Zhou; Gloria Choi; David J. Anderson



The Mesoderm Specification Factor Twist in the Life Cycle of Jellyfish  

Microsoft Academic Search

The basic helix-loop-helix (bHLH) transcription factor Twist is highly conserved from Drosophila to vertebrates and plays a major role in mesoderm specification of triploblasts. The presence of a Twist homologue in diploblasts such as the cnidarian Podocoryne carnea raises questions on the evolution of mesoderm, the third cell layer characteristic for triploblasts. Podocoryne Twist is expressed in the early embryo

Jürg Spring; Nathalie Yanze; Arnoud M. Middel; Michael Stierwald; Hans Gröger; Volker Schmid



The Enhancer of split and Achaete-Scute complexes of Drosophilids derived from simple ur-complexes preserved in mosquito and honeybee  

Microsoft Academic Search

: BACKGROUND: In Drosophila melanogaster the Enhancer of split-Complex [E(spl)-C] consists of seven highly related genes encoding basic helix-loop-helix (bHLH) repressors and intermingled, four genes that belong to the Bearded (Brd) family. Both gene classes are targets of the Notch signalling pathway. The Achaete-Scute-Complex [AS-C] comprises four genes encoding bHLH activators. The question arose how these complexes evolved with regard

Rebekka Schlatter; Dieter Maier



Sonic Hedgehog–Regulated Oligodendrocyte Lineage Genes Encoding bHLH Proteins in the Mammalian Central Nervous System  

Microsoft Academic Search

During development, basic helix–loop–helix (bHLH) proteins regulate formation of neurons from multipotent progenitor cells. However, bHLH factors linked to gliogenesis have not been described. We have isolated a pair of oligodendrocyte lineage genes (Olg-1 and Olg-2) that encode bHLH proteins and are tightly associated with development of oligodendrocytes in the vertebrate central nervous system (CNS). Ectopic expression of Olg-1 in

Q. Richard Lu; Dong-in Yuk; John A Alberta; Zhimin Zhu; Inka Pawlitzky; Joanne Chan; Andrew P McMahon; Charles D Stiles; David H Rowitch



Prostacyclin-induced hyperthermia - Implication of a protein mediator  

NASA Technical Reports Server (NTRS)

The mechanism of the prostacyclin-linked hyperthermia is studied in rabbits. Results show that intracerebroventricular administration of prostacyclin (PGI2) induces dose-related hyperthermia at room temperature (21 C), as well as at low (4 C) and high (30 C) ambient temperatures. It is found that this PGI2-induced hyperthermia is not mediated by its stable metabolite 6-keto prostaglandin F-1(alpha). Only one of the three anion transport systems, the liver transport system, appears to be important to the central inactivation of pyrogen, prostaglandin E2, and PGI2. Phenoxybenzamine and pimozide have no thermolytic effect on PGI2-induced hyperthermia, while PGI2 still induces hyperthermia after norepinephrine (NE) and dopamine levels are depleted by 6-hydroxydopamine. Indomethacin and SC-19220 (a PG antagonist) do not antagonize PGI2 induced hyperthermia, while theophylline does not accentuate the PGI2-induced hyperthermia. However, the hyperthermic response to PGI2 is attenuated by central administration of the protein synthesis inhibitor, anisomycin. It is concluded that PGI2-induced hyperthermia is not induced by NE, dopamine, or cyclic AMP, but rather that a protein mediator is implicated in the induction of fever by PG12.

Kandasamy, S. B.; Williams, B. A.



Allosteric Effects of RuvA Protein, ATP, and DNA on RuvB Protein-Mediated ATP Hydrolysis  

E-print Network

Allosteric Effects of RuvA Protein, ATP, and DNA on RuvB Protein-Mediated ATP Hydrolysis Paul E ABSTRACT: A detailed characterization of RuvB protein-mediated ATP hydrolysis in the presence of RuvA protein has provided (a) the steady-state kinetic parameters of ATP hydrolysis within a RuvAB complex

Cox, Michael M.


Nucleic Acid Conformational Changes Essential for HIV-1 Nucleocapsid Protein-mediated Inhibition of  

E-print Network

Nucleic Acid Conformational Changes Essential for HIV-1 Nucleocapsid Protein-mediated Inhibition) is a nucleic acid chaperone protein that has been shown to greatly facilitate the nucleic acid rearrangements and a TAR-containing acceptor RNA molecule, we find that when both nucleic acids are present, NC facilitates

Levin, Judith G.


Protein-mediated loops and phase transition in nonthermal denaturation of DNA This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Protein-mediated loops and phase transition in nonthermal denaturation of DNA This article has been and Experiment Protein-mediated loops and phase transition in nonthermal denaturation of DNA Karen G Petrosyan a statistical mechanical model to study nonthermal denaturation of DNA in the presence of protein-mediated loops


Tipping the MYC–MIZ1 balance: targeting the HUWE1 ubiquitin ligase selectively blocks MYC-activated genes  

PubMed Central

MYC family oncoproteins (MYC, N-MYC and L-MYC) function as basic helix-loop-helix-leucine zipper (bHLH-Zip) transcription factors that are activated (i.e., overexpressed) in well over half of all human malignancies (Boxer & Dang, 2001; Beroukhim et al, 2010). In this issue of EMBO Molecular Medicine, Eilers and colleagues (Peter et al, 2014) describe a novel approach to disable MYC, whereby inhibition of the ubiquitin ligase HUWE1 stabilizes MIZ1 and leads to the selective repression of MYC-activated target genes. See also: S Peter et al (December 2014) PMID:25368331

Schaub, Franz X; Cleveland, John L



A Novel bHLH-PAS Factor with Close Sequence Similarity to Hypoxia-Inducible Factor 1alpha (HIF1alpha ) Regulates the VEGF, Expression and is Potentially Involved in Lung and Vascular Development  

Microsoft Academic Search

We have isolated and characterized a cDNA for a novel Per-Arnt\\/AhR-Sim basic helix--loop--helix (bHLH-PAS) factor that interacts with the Ah receptor nuclear translocator (Arnt), and its predicted amino acid sequence exhibits significant similarity to the hypoxia-inducible factor 1alpha (HIF1alpha ) and Drosophila trachealess (dTrh) gene product. The HIF1alpha -like factor (HLF) encoded by the isolated cDNA bound the hypoxia-response element

Masatsugu Ema; Shinichiro Taya; Noboru Yokotani; Kazuhiro Sogawa; Youichi Matsuda; Yoshiaki Fujii-Kuriyama



Myomaker is essential for muscle regeneration  

PubMed Central

Regeneration of injured adult skeletal muscle involves fusion of activated satellite cells to form new myofibers. Myomaker is a muscle-specific membrane protein required for fusion of embryonic myoblasts, but its potential involvement in adult muscle regeneration has not been explored. We show that myogenic basic helix–loop–helix (bHLH) transcription factors induce myomaker expression in satellite cells during acute and chronic muscle regeneration. Moreover, genetic deletion of myomaker in adult satellite cells completely abolishes muscle regeneration, resulting in severe muscle destruction after injury. Myomaker is the only muscle-specific protein known to be absolutely essential for fusion of embryonic and adult myoblasts. PMID:25085416

Millay, Douglas P.; Sutherland, Lillian B.; Bassel-Duby, Rhonda



Protein-mediated Loops and Phase Transition in Nonthermal Denaturation of DNA  

E-print Network

We use a statistical mechanical model to study nonthermal denaturation of DNA in the presence of protein-mediated loops. We find that looping proteins which randomly link DNA bases located at a distance along the chain could cause a first-order phase transition. We estimate the denaturation transition time near the phase transition, which can be compared with experimental data. The model describes the formation of multiple loops via dynamical (fluctuational) linking between looping proteins, that is essential in many cellular biological processes.

K. G. Petrosyan; Chin-Kun Hu



Mechanisms and Regulation of Protein-Mediated Cellular Fatty Acid Uptake: Molecular, Biochemical, and Physiological Evidence  

NSDL National Science Digital Library

In recent years, there has been considerable debate as to whether fatty acid is transported into cells or diffuses rapidly into the cell. It now appears that this debate is less strident, as it has been acknowledged recently that evidence supporting passive diffusion as the main mechanism for fatty acid uptake is apparently in error, since "previous reports for rapid flip-flop were based on an incorrect interpretation of the measurements" (79), Because of this (79) and other experiments (78), it has been concluded that "the lipid bilayer portion of biological membranes may present a significant barrier to transport of FFA across cell membranes" (36) and that "flip-flop is the rate limiting step for FFA transport across lipid vesicles" (78). Furthermore, "this implies that at least certain biological membranes may require protein-mediated transporters to catalyze the flip-flop step" (78). Since we (13, 27Â?29, 73, 97, 98, 100) and others (32, 45, 54) have previously provided considerable support for the protein-mediated entry of long-chain fatty acids into the cell, especially in metabolically important tissues such as heart and skeletal muscle, we concur with these recent conclusions (36, 78, 79) that (membrane-associated) proteins are involved in cellular fatty acid uptake.



MAP Kinases have different functions in Dictyostelium G Protein-Mediated Signaling  

PubMed Central

Extracellular signal regulated kinases (ERKs) are a class of MAP kinases that function in many signaling pathways in eukaryotic cells and in some cases, a single stimulus can activate more than one ERK suggesting functional redundancy or divergence from a common pathway. Dictyostelium discoideum encodes only two MAP kinases, ERK1 and ERK2, that both function during the developmental life cycle. To determine if ERK1 and ERK2 have overlapping functions, chemotactic and developmental phenotypes of erk1? and erk2? mutants were assessed with respect to G protein-mediated signal transduction pathways. ERK1 was specifically required for G?5-mediated tip morphogenesis and inhibition of folate chemotaxis but not for cAMP-stimulated chemotaxis or cGMP accumulation. ERK2 was the primary MAPK phosphorylated in response to folate or cAMP stimulation. Cell growth was not altered in erk1?, erk2? or erk1?erk2? mutants but each mutant displayed a different pattern of cell sorting in chimeric aggregates. The distribution of GFP-ERK1 or GFP-ERK2 fusion proteins in the cytoplasm and nucleus was not grossly altered in cells stimulated with cAMP or folate. These results suggest ERK1 and ERK2 have different roles in G protein-mediated signaling during growth and development. PMID:20079430

Nguyen, Hoai-Nghia; Raisley, Brent; Hadwiger, Jeffrey A.



HaloTag Protein-Mediated Specific Labeling of Living Cells with Quantum Dots  

PubMed Central

Quantum dots emerge as an attractive alternative to small molecule fluorophores as fluorescent tags for in vivo cell labeling and imaging. This communication presents a method for specific labeling of live cells using quantum dots. The labeling is mediated by HaloTag protein expressed at the cell surface which forms a stable covalent adduct with its ligand (HaloTag ligand). The labeling can be performed in one single step with quantum dot conjugates that are functionalized with HaloTag ligand, or in two steps with biotinylated HaloTag ligand first and followed by streptavidin coated quantum dots. Live cell fluorescence imaging indicates that the labeling is specific and takes place at the cell surface. This HaloTag protein-mediated cell labeling method should facilitate the application of quantum dots for live cell imaging. PMID:18621022

So, Min-kyung; Yao, Hequan; Rao, Jianghong



Biochemistry 1995, 34, 9809-9818 9809 RuvB Protein-Mediated ATP Hydrolysis: Functional Asymmetry in the RuvB  

E-print Network

Biochemistry 1995, 34, 9809-9818 9809 RuvB Protein-Mediated ATP Hydrolysis: Functional Asymmetry Manuscript Received May 19, 1995@ ABSTRACT:A survey of RuvB protein-mediated ATP hydrolysis yields inhibition by ADP. Addition of ATP to 3 mM triggers an immediate resumption of ATP hydrolysis

Cox, Michael M.


A Juvenile Hormone Transcription Factor Bmdimm-Fibroin H Chain Pathway Is Involved in the Synthesis of Silk Protein in Silkworm, Bombyx mori.  


The genes responsible for silk biosynthesis are switched on and off at particular times in the silk glands of Bombyx mori. This switch appears to be under the control of endogenous and exogenous hormones. However, the molecular mechanisms by which silk protein synthesis is regulated by the juvenile hormone (JH) are largely unknown. Here, we report a basic helix-loop-helix transcription factor, Bmdimm, its silk gland-specific expression, and its direct involvement in the regulation of fibroin H-chain (fib-H) by binding to an E-box (CAAATG) element of the fib-H gene promoter. Far-Western blots, enzyme-linked immunosorbent assays, and co-immunoprecipitation assays revealed that Bmdimm protein interacted with another basic helix-loop-helix transcription factor, Bmsage. Immunostaining revealed that Bmdimm and Bmsage proteins are co-localized in nuclei. Bmdimm expression was induced in larval silk glands in vivo, in silk glands cultured in vitro, and in B. mori cell lines after treatment with a JH analog. The JH effect on Bmdimm was mediated by the JH-Met-Kr-h1 signaling pathway, and Bmdimm expression did not respond to JH by RNA interference with double-stranded BmKr-h1 RNA. These data suggest that the JH regulatory pathway, the transcription factor Bmdimm, and the targeted fib-H gene contribute to the synthesis of fibroin H-chain protein in B. mori. PMID:25371208

Zhao, Xiao-Ming; Liu, Chun; Jiang, Li-Jun; Li, Qiong-Yan; Zhou, Meng-Ting; Cheng, Ting-Cai; Mita, Kazuei; Xia, Qing-You



Dynamic expression of Notch-dependent neurogenic markers in the chick embryonic nervous system  

PubMed Central

The establishment of a functional nervous system requires a highly orchestrated process of neural proliferation and differentiation. The evolutionary conserved Notch signaling pathway is a key regulator of this process, regulating basic helix-loop-helix (bHLH) transcriptional repressors and proneural genes. However, little is known about downstream Notch targets and subsequently genes required for neuronal specification. In this report, the expression pattern of Transgelin 3 (Tagln3), Chromogranin A (Chga) and Contactin 2 (Cntn2) was described in detail during early chick embryogenesis. Expression of these genes was largely restricted to the nervous system including the early axon scaffold populations, cranial ganglia and spinal motor neurons. Their temporal and spatial expression were compared with the neuronal markers Nescient Helix-Loop-Helix 1 (Nhlh1), Stathmin 2 (Stmn2) and HuC/D. We show that Tagln3 is an early marker for post-mitotic neurons whereas Chga and Cntn2 are expressed in mature neurons. We demonstrate that inhibition of Notch signaling during spinal cord neurogenesis enhances expression of these markers. This data demonstrates that Tagln3, Chga and Cntn2 represent strong new candidates to contribute to the sequential progression of vertebrate neurogenesis. PMID:25565981

Ratié, Leslie; Ware, Michelle; Jagline, Hélène; David, Véronique; Dupé, Valérie



Inhibitor of DNA Binding 4 (ID4) Regulation of Adipocyte Differentiation and Adipose Tissue Formation in Mice*  

PubMed Central

Inhibitor of DNA binding 4 (ID4) is a helix-loop-helix protein that heterodimerizes with basic helix-loop-helix transcription factors inhibiting their function. ID4 expression is important for adipogenic differentiation of the 3T3-L1 cell line, and inhibition of ID4 is associated with a concomitant decrease in CCAAT/enhancer-binding protein ? and peroxisome proliferator-activated receptor ? mRNA and protein expression. Mice with a homozygous deletion of Id4 (Id4?/?) have reduced body fat and gain much less weight compared with wild-type littermates when placed on diets with high fat content. Mouse embryonic fibroblasts (MEFs) isolated from Id4?/? mice have reduced adipogenic potential when compared with wild-type MEFs. In agreement with changes in morphological differentiation, the levels of CCAAT/enhancer-binding protein ? and peroxisome proliferator-activated receptor ? were also reduced in MEFs from Id4?/? mice. Our results demonstrate the importance of ID4 in adipocyte differentiation and the implications of this regulation for adipose tissue formation. PMID:20460371

Murad, Joana M.; Place, Chelsea S.; Ran, Cong; Hekmatyar, Shahryar K. N.; Watson, Nathan P.; Kauppinen, Risto A.; Israel, Mark A.



The bHLH Transcription Factor HBI1 Mediates the Trade-Off between Growth and Pathogen-Associated Molecular Pattern–Triggered Immunity in Arabidopsis[W][OPEN  

PubMed Central

The trade-off between growth and immunity is crucial for survival in plants. However, the mechanism underlying growth-immunity balance has remained elusive. The PRE-IBH1-HBI1 tripartite helix-loop-helix/basic helix-loop-helix module is part of a central transcription network that mediates growth regulation by several hormonal and environmental signals. Here, genome-wide analyses of HBI1 target genes show that HBI1 regulates both overlapping and unique targets compared with other DNA binding components of the network in Arabidopsis thaliana, supporting a role in specifying network outputs and fine-tuning feedback regulation. Furthermore, HBI1 negatively regulates a subset of genes involved in immunity, and pathogen-associated molecular pattern (PAMP) signals repress HBI1 transcription. Constitutive overexpression and loss-of-function experiments show that HBI1 inhibits PAMP-induced growth arrest, defense gene expression, reactive oxygen species production, and resistance to pathogen. These results show that HBI1, as a component of the central growth regulation circuit, functions as a major node of crosstalk that mediates a trade-off between growth and immunity in plants. PMID:24550223

Fan, Min; Bai, Ming-Yi; Kim, Jung-Gun; Wang, Tina; Oh, Eunkyoo; Chen, Lawrence; Park, Chan Ho; Son, Seung-Hyun; Kim, Seong-Ki; Mudgett, Mary Beth; Wang, Zhi-Yong



The Respiratory Syncytial Virus (RSV) Nonstructural proteins mediate RSV suppression of glucocorticoid receptor transactivation  

PubMed Central

Respiratory syncytial virus (RSV)-induced bronchiolitis in infants is not responsive to glucocorticoids. We have shown that RSV infection impairs glucocorticoid receptor (GR) function. In this study, we have investigated the mechanism by which RSV impairs GR function. We have shown that RSV repression of GR-induced transactivation is not mediated through a soluble autocrine factor. Knock-down of mitochondrial antiviral signaling protein (MAVS), but not retinoic acid-inducible gene 1 (RIG-I) or myeloid differentiation primary response gene 88 (MyD88), impairs GR-mediated gene activation even in mock-infected cells. Over-expression of the RSV nonstructural protein NS1, but not NS2, impairs glucocorticoid-induced transactivation and viruses deleted in NS1 and/or NS2 are unable to repress glucocorticoid-induction of the known GR regulated gene glucocorticoid-inducible leucine zipper (GILZ). These data suggest that the RSV nonstructural proteins mediate RSV repression of GR-induced transactivation and that inhibition of the nonstructural proteins may be a viable target for therapy against RSV-related disease. PMID:24418538

Webster Marketon, Jeanette I.; Corry, Jacqueline; Teng, Michael N.



Rhizobium nod factor signaling. Evidence for a g protein-mediated transduction mechanism  

PubMed Central

Rhizobium nodulation (Nod) factors are lipochitooligosaccharide signals that elicit key symbiotic developmental responses in the host legume root. In this study, we have investigated Nod factor signal transduction in the Medicago root epidermis by using a pharmacological approach in conjunction with transgenic plants expressing the Nod factor-responsive reporter construct pMtENOD12-GUS. Evidence for the participation of heterotrimeric G proteins in Nod factor signaling has come from three complementary observations: (1) the amphiphilic peptides mastoparan and Mas7, known G protein agonists, are able to mimic Nod factor-induced epidermal MtENOD12 expression; (2) growth of plants in nodulation-inhibiting conditions (10 mM NH4NO3) leads to a dramatic reduction in both Nod factor- and mastoparan-elicited gene expression; and (3) bacterial pertussis toxin, a well-characterized G protein antagonist, blocks the activities of both the Nod factor and mastoparan. In addition, we have found that antagonists that interfere with phospholipase C activity (neomycin and U73122) and Ca2+ influx/release (EGTA, La3+, and ruthenium red) block Nod factor/mastoparan activity. Taken together, these results are consistent with a Nod factor signal transduction mechanism involving G protein mediation coupled to the activation of both phosphoinositide and Ca2+ second messenger pathways. PMID:9596628

Pingret, JL; Journet, EP; Barker, DG



Targeting antitumor effect of rhTNF-? fusion protein mediated by matrix metalloproteinase-2.  


The aim of this study was to examine the tumor therapy, targeting effects and side effects of tumor-targeting rhTNF-? fusion protein mediated by matrix metalloproteinase-2 in an animal model in order to provide experimental data for future development of drugs. The median lethal dose (LD50) was obtained from acute toxicity experiments. The A549 lung cancer xenograft model was established, and then randomly divided into the saline, standard substance, and low-, middle- and high-dose fusion protein experiment groups. Each group was administered drugs for 18 days. The length and width of the xenografts were measured every three days, after which the xenograft growth curve was drawn. The mice were sacrificed in each group following treatment and the tumor volume and weight were measured. The targeting, effectiveness and toxicity of the transformed fusion protein, and pathological changes of tumor and organ tissues were examined by hematoxylin and eosin (H&E) staining. Additionally, biochemical markers were used to detect damage of various organs after protein processing. Cell apoptosis and angiogenesis were determined using terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling (TUNEL) testing and immunohistochemistry, respectively, in different dose groups. Tumor growth was markedly retarded in the high-dose experimental and standard hTNF-? groups with antitumor rates of 85.91 and 72.25%, respectively, as compared with the control group. Furthermore, the tumor tissue showed obvious apoptosis (the apoptotic index was 78.78 and 66.65%, respectively) and pathological changes in the high-dose experimental and standard hTNF-? groups. Tumor angiogenesis in each fusion protein group was inhibited (P<0.01) and the biochemical markers of various organs were greatly reduced in the high-dose experimental group (P<0.05). This finding indicated that slight toxic effects of fusion proteins were evident for the heart, liver and kidney. The reforming fusion protein can therefore target tumor tissues and efficiently kill tumor cells, with few side effects. PMID:25421954

Shao, Xin; Ren, Hui; Wang, Yue-Li; Wang, Fa; Hou, Gan; Huang, Di-Nan



The Basics  

ERIC Educational Resources Information Center

These articles are presented as an aide in teaching basic subjects. This issue examines reading diagnosis, food preservation, prime numbers, electromagnets, acting out in language arts, self-directed spelling activities, and resources for environmental education. (Editor/RK)

Indrisano, Roselmina; And Others



Fluoridation Basics  


... . Oral Health home School-Based Dental Sealant Programs Community Water Fluoridation Fluoridation Basics Benefits Guidelines ... Health Engineering & Operations Infection Control School-Based Dental Sealant Programs Community Water Fluoridation FAQs Community Water Fluoridation ...


Energy Basics  

NSDL National Science Digital Library

Demos and activities in this lesson are intended to illustrate the basic concepts of energy science—work, force, energy, power etc., and the relationships among them. The "lecture" portion of the lesson includes many demonstrations to keep students engaged, yet has high expectations for students to perform energy-related calculations and convert units. A homework assignment and quiz are provided to reinforce and assess these basic engineering science concepts.

Office of Educational Partnerships,


Body Basics  


... more about how the body works, what basic human anatomy is, and what happens when parts of the body don't function properly. Blood Bones, Muscles, and Joints Brain and Nervous System Digestive System Endocrine System Eyes Female Reproductive System ...


Basic Science.  

ERIC Educational Resources Information Center

Instructional materials are provided for a course that covers basic concepts of physics and chemistry. Designed for use in a workplace literacy project developed by Mercer County Community College (New Jersey) and its partners, the course describes applications of these concepts to real-life situations, with an emphasis on applications of…

Mercer County Community Coll., Trenton, NJ.


The HevCaLP Protein Mediates Binding Specificity of the Cry1A Class of Bacillus thuringiensis Toxins in Heliothis Virescens  

E-print Network

The HevCaLP Protein Mediates Binding Specificity of the Cry1A Class of Bacillus thuringiensis strain to Cry1Ac toxin from Bacillus thuringiensis. This suggests that HevCaLP functions as a Cry1Ac of transgenic plants producing Cry proteins from the bacterium Bacillus thuringiensis (Bt)1 has led

Jurat-Fuentes, Juan Luis


Contour Basics  

NSDL National Science Digital Library

Contour Basics is an exercise designed to introduce students to contour plots. The Contour Activity is a great on-line resource that starts slowly and increases in difficulty. It teaches students basic techniques for generating contours, introduces students to the subtleties of generating contour plots with sparse data, provides many opportunities for students to assess their own progress and understanding and has complete on-line drawing capabilities. The exercise is geared toward atmospheric and oceanic sciences but is beneficial for all geoscience students. In addition to the exercise, this site includes information on teaching materials, teaching notes and tips, assessment suggestions and additional references. This activity is part of the Starting Point Collection:

Ackerman, Steve


Basic Immunology  

NSDL National Science Digital Library

Some individuals might blanch at the idea of a "basic" immunology overview, but Professor Vladimir V. Klimov provides just such a resource on this site. As the homepage notes, the site is designed to assist undergraduate students learning about the basics of immunology through essays, images, animations, quizzes, case histories, and external links. Visitors can begin by looking over the "Table of Contents" area, which includes seven complete chapters of information. These chapters include "The Immune Responses", "Effector Activity", and "Functional Organization of the Immune System". While some of the materials on the site require a paid subscription, there's enough free material here to get students on their way to learning more about this field of study.

Klimov, Vladimir V.


Assignment of the hypoxia-inducible factor 1alpha gene to a region of conserved synteny on mouse chromosome 12 and human chromosome 14q.  


Hypoxia-inducible factor 1 (HIF-1) is a basic helix-loop-helix transcription factor that mediates homeostatic responses to hypoxia. HIF-1 is a heterodimer consisting of HIF-1alpha, which is encoded by the HIF1A gene, complexed with HIF-1beta, which is encoded by the ARNT gene. In this paper we report the assignment of Hif1a and HIF1A to mouse chromosome 12 and human chromosome 14, respectively. HIF1A was assigned to human chromosome 14q21-q24 by analysis of somatic cell hybrids and by fluorescence in situ hybridization. Hif1a was localized by interspecific backcross analysis within a region of mouse chromosome 12 encompassing >30 cM that demonstrates conservation of synteny with a region of human chromosome 14 extending from PAX9 at 14q12-q13 to IGHC at 14q32.33. PMID:8786149

Semenza, G L; Rue, E A; Iyer, N V; Pang, M G; Kearns, W G



Iron assimilation and transcription factor controlled synthesis of riboflavin in plants.  


Iron homeostasis is vital for many cellular processes and requires a precise regulation. Several iron efficient plants respond to iron starvation with the excretion of riboflavin and other flavins. Basic helix-loop-helix transcription factors (TF) are involved in the regulation of many developmental processes, including iron assimilation. Here we describe the isolation and characterisation of two Arabidopsis bHLH TF genes, which are strongly induced under iron starvation. Their heterologous ectopic expression causes constitutive, iron starvation independent excretion of riboflavin. The results show that both bHLH TFs represent an essential component of the regulatory pathway connecting iron deficiency perception and riboflavin excretion and might act as integrators of various stress reactions. PMID:17260143

Vorwieger, A; Gryczka, C; Czihal, A; Douchkov, D; Tiedemann, J; Mock, H-P; Jakoby, M; Weisshaar, B; Saalbach, I; Bäumlein, H



The conserved WRPW motif of Hes6 mediates proteasomal degradation  

SciTech Connect

Hes6 belongs to a subfamily of basic helix-loop-helix transcription factors that includes Drosophila Hairy and Enhancer of split genes. Like other members of the family, Hes6 features the WRPW motif which is consisted just of four amino acids at its C-terminus. Here, we show that WRPW motif deletion mutant protein is substantially stabilized in comparison to the full length protein and that the enhanced stability is due to its resistance to proteasomal degradation. The WRPW motif also appears to be sufficient for acceleration of proteolysis as its fusion to two heterologous proteins, the green fluorescent protein (GFP) of Aequoria victoria and Gal4 DNA binding domain of Saccharomyces cerevisiae, significantly destabilized the proteins. These findings demonstrate a novel function of this conserved motif as a degradation signal and raise the possibility of utilizing it for controlling the level of ectopically expressed gene products.

Kang, Seon Ah [Division of Molecular Life Sciences and Center for Cell Signaling Research, Ewha Womans University, 11-1 Daehyun-dong, Seodaemun-gu, Seoul 120-750 (Korea, Republic of); Seol, Jae Hong [Seoul National University School of Biological Sciences, San 56-1, Shillim-dong, Kwanak-gu, Seoul 151-742 (Korea, Republic of); Kim, Jaesang [Division of Molecular Life Sciences and Center for Cell Signaling Research, Ewha Womans University, 11-1 Daehyun-dong, Seodaemun-gu, Seoul 120-750 (Korea, Republic of)]. E-mail:



Novel roles for the MiTF/TFE family of transcription factors in organelle biogenesis, nutrient sensing, and energy homeostasis.  


The MiTF/TFE family of basic helix-loop-helix leucine zipper transcription factors includes MITF, TFEB, TFE3, and TFEC. The involvement of some family members in the development and proliferation of specific cell types, such as mast cells, osteoclasts, and melanocytes, is well established. Notably, recent evidence suggests that the MiTF/TFE family plays a critical role in organelle biogenesis, nutrient sensing, and energy metabolism. The MiTF/TFE family is also implicated in human disease. Mutations or aberrant expression of most MiTF/TFE family members has been linked to different types of cancer. At the same time, they have recently emerged as novel and very promising targets for the treatment of neurological and lysosomal diseases. The characterization of this fascinating family of transcription factors is greatly expanding our understanding of how cells synchronize environmental signals, such as nutrient availability, with gene expression, energy production, and cellular homeostasis. PMID:24477476

Martina, José A; Diab, Heba I; Li, Huiqing; Puertollano, Rosa



Binding of carbon nanotube to BMP receptor 2 enhances cell differentiation and inhibits apoptosis via regulating bHLH transcription factors  

PubMed Central

Biomaterials that can drive stem cells to an appropriate differentiation level and decrease apoptosis of transplanted cells are needed in regenerative medicine. Nanomaterials are promising novel materials for such applications. Here we reported that carboxylated multiwalled carbon nanotube (MWCNT 1) promotes myogenic differentiation of mouse myoblast cells and inhibits cell apoptosis under the differentiation conditions by regulating basic helix-loop-helix transcription factors. MWCNT 1 attenuates bone morphogenetic protein receptor (BMPR) signaling activity by binding to BMPR2 and attenuating the phosphorylation of BMPR1. This molecular understanding allowed us to tune stem cell differentiation to various levels by chemical modifications, demonstrating human control of biological activities of nanoparticles and opening an avenue for potential applications of nanomaterials in regenerative medicine. PMID:22573038

Zhang, Y; Mu, Q; Zhou, H; Vrijens, K; Roussel, M F; Jiang, G; Yan, B



Unique CCT repeats mediate transcription of the TWIST1 gene in mesenchymal cell lines  

SciTech Connect

TWIST1, a basic helix-loop-helix transcription factor, plays critical roles in embryo development, cancer metastasis and mesenchymal progenitor differentiation. Little is known about transcriptional regulation of TWIST1 expression. Here we identified DNA sequences responsible for TWIST1 expression in mesenchymal lineage cell lines. Reporter assays with TWIST1 promoter mutants defined the -102 to -74 sequences that are essential for TWIST1 expression in human and mouse mesenchymal cell lines. Tandem repeats of CCT, but not putative CREB and NF-{kappa}B sites in the sequences substantially supported activity of the TWIST1 promoter. Electrophoretic mobility shift assay demonstrated that the DNA sequences with the CCT repeats formed complexes with nuclear factors, containing, at least, Sp1 and Sp3. These results suggest critical implication of the CCT repeats in association with Sp1 and Sp3 factors in sustaining expression of the TWIST1 gene in mesenchymal cells.

Ohkuma, Mizue [Maxillofacial Orthognathics, Graduate School, Tokyo Medical and Dental University, Tokyo 113-8549 (Japan); Human Gene Sciences Center, Tokyo Medical and Dental University, Tokyo 113-8510 (Japan); Funato, Noriko [Maxillofacial Orthognathics, Graduate School, Tokyo Medical and Dental University, Tokyo 113-8549 (Japan); Higashihori, Norihisa [Maxillofacial Orthognathics, Graduate School, Tokyo Medical and Dental University, Tokyo 113-8549 (Japan); Murakami, Masanori [Human Gene Sciences Center, Tokyo Medical and Dental University, Tokyo 113-8510 (Japan); Ohyama, Kimie [Maxillofacial Orthognathics, Graduate School, Tokyo Medical and Dental University, Tokyo 113-8549 (Japan); Nakamura, Masataka [Human Gene Sciences Center, Tokyo Medical and Dental University, Tokyo 113-8510 (Japan)]. E-mail:



Atoh1-lineal neurons are required for hearing and for the survival of neurons in the spiral ganglion and brainstem accessory auditory nuclei  

PubMed Central

Atoh1 is a basic helix-loop-helix transcription factor necessary for the specification of inner ear hair cells and central auditory system neurons derived from the rhombic lip. We used the Cre-loxP system and two Cre-driver lines (Egr2Cre and Hoxb1Cre) to delete Atoh1 from different regions of the cochlear nucleus (CN) and accessory auditory nuclei (AAN). Adult Atoh1-conditional knockout mice (Atoh1CKO) are behaviorally deaf, have diminished auditory brainstem evoked responses and disrupted CN and AAN morphology and connectivity. In addition, Egr2; Atoh1CKO mice lose spiral ganglion neurons in the cochlea and AAN neurons during the first 3 days of life, revealing a novel critical period in the development of these neurons. These new mouse models of predominantly central deafness illuminate the importance of the CN for support of a subset of peripheral and central auditory neurons. PMID:19741118

Maricich, Stephen M.; Xia, Anping; Mathes, Erin L.; Wang, Vincent Y.; Oghalai, John S.; Fritzsch, Bernd; Zoghbi, Huda Y.



An essential role for the transcription factor HEB in thymocyte survival, Tcra rearrangement and the development of natural killer T cells  

PubMed Central

E proteins are basic helix-loop-helix transcription factors that regulate many key aspects of lymphocyte development. Thymocytes express multiple E proteins that are thought to provide cooperative and compensatory functions crucial for T cell differentiation. Contrary to that, we report here that the E protein HEB was uniquely required at the CD4+CD8+ double-positive (DP) stage of T cell development. Thymocytes lacking HEB showed impaired survival, failed to make rearrangements of variable-? (V?) segments to distal joining-? (J?) segments in the gene encoding the T cell antigen receptor ?-chain (Tcra) and had a profound, intrinsic block in the development of invariant natural killer T cells (iNKT cells) at their earliest progenitor stage. Thus, our results show that HEB is a specific and essential factor in T cell development and in the generation of the iNKT cell lineage, defining a unique role for HEB in the regulation of lymphocyte maturation. PMID:20154672

D’Cruz, Louise M; Knell, Jamie; Fujimoto, Jessica K; Goldrath, Ananda W



Accurate discrimination of bHLH domains in plants, animals, and fungi using biologically meaningful sites  

PubMed Central

Background The highly conserved bHLH (basic Helix-Loop-Helix) domain, found in many transcription factors, has been well characterized separately in Plants, Animals, and Fungi. While conserved, even functionally constrained sites have varied since the Eukarya split. Our research identifies those slightly variable sites that were highly characteristic of Plants, Animals, or Fungi. Results Through discriminant analysis, we identified five highly discerning DNA-binding amino acid sites. Additionally, by incorporating Kingdom specific HMMs, we were able to construct a tool to quickly and accurately identify and classify bHLH sequences using these sites. Conclusions We conclude that highly discerning sites identified through our analysis were likely under functional constraints specific to each Kingdom. We also demonstrated the utility of our tool by identifying and classifying previously unknown bHLH domains in both characterized genomes and from sequences in a large environmental sample. PMID:22920570



Binding of carbon nanotube to BMP receptor 2 enhances cell differentiation and inhibits apoptosis via regulating bHLH transcription factors.  


Biomaterials that can drive stem cells to an appropriate differentiation level and decrease apoptosis of transplanted cells are needed in regenerative medicine. Nanomaterials are promising novel materials for such applications. Here we reported that carboxylated multiwalled carbon nanotube (MWCNT 1) promotes myogenic differentiation of mouse myoblast cells and inhibits cell apoptosis under the differentiation conditions by regulating basic helix-loop-helix transcription factors. MWCNT 1 attenuates bone morphogenetic protein receptor (BMPR) signaling activity by binding to BMPR2 and attenuating the phosphorylation of BMPR1. This molecular understanding allowed us to tune stem cell differentiation to various levels by chemical modifications, demonstrating human control of biological activities of nanoparticles and opening an avenue for potential applications of nanomaterials in regenerative medicine. PMID:22573038

Zhang, Y; Mu, Q; Zhou, H; Vrijens, K; Roussel, M F; Jiang, G; Yan, B



PIFs: pivotal components in a cellular signaling hub  

PubMed Central

A small subset of basic helix–loop–helix transcription factors called PIFs [phytochrome (phy)-interacting factors] act to repress seed germination, promote seedling skotomorphogenesis and promote shade-avoidance through regulated expression of over a thousand genes. Light-activated phy molecules directly reverse these activities by inducing rapid degradation of the PIF proteins. Here, we review recent advances in dissecting this signaling pathway and examine emerging evidence that indicates that other pathways also converge to regulate PIF activity, including the gibberellin pathway, the circadian clock and high temperature. The PIFs thus have broader roles than previously appreciated, functioning as a cellular signaling hub that integrates multiple signals to orchestrate regulation of the transcriptional network that drives multiple facets of downstream morphogenesis. The relative contributions of the individual PIFs to this spectrum of regulatory functions ranges from quantitatively redundant to qualitatively distinct. PMID:20833098

Leivar, Pablo; Quail, Peter H.



Three redundant brassinosteroid early response genes encode putative bHLH transcription factors required for normal growth.  

PubMed Central

Brassinosteroids (BRs) are a class of polyhydroxylated steroids that are important regulators of plant growth and development. We have identified three closely related basic helix-loop-helix (bHLH) transcription factors, BEE1, BEE2, and BEE3, as products of early response genes required for full BR response. Comparison of the phenotypes of plants that overexpress BEE1 with bee1 bee2 bee3 triple-knockout mutant plants suggests that BEE1, BEE2, and BEE3 are functionally redundant positive regulators of BR signaling. Expression of BEE1, BEE2, and BEE3 is also regulated by other hormones, notably abscisic acid (ABA), a known antagonist of BR signaling. Reduced ABA response in plants overexpressing BEE1 suggests that BEE proteins may function as signaling intermediates in multiple pathways. PMID:12454087

Friedrichsen, Danielle M; Nemhauser, Jennifer; Muramitsu, Takamichi; Maloof, Julin N; Alonso, José; Ecker, Joseph R; Furuya, Masaki; Chory, Joanne



New insights into the role of ID proteins in breast cancer metastasis: a MET affair  

PubMed Central

The establishment of lethal metastases depends on the capacity of a small number of cancer cells to regenerate a tumor after entering a target organ. Stankic and colleagues have identified a role for the inhibitor of differentiation protein, ID1, as a critical regulator of breast cancer stem-like properties and metastatic colonization. Under the control of tumor growth factor-beta signaling, ID1 induces mesenchymal-epithelial transition at the metastatic site by antagonizing the activity of the basic helix-loop-helix transcription factor Twist1. This study sheds light on mechanisms that initiate metastatic outgrowth, and strengthens the concept that epithelial-mesenchymal plasticity is crucial at different stages of metastasis.



Molecular mechanisms of epithelial–mesenchymal transition  

PubMed Central

The transdifferentiation of epithelial cells into motile mesenchymal cells, a process known as epithelial–mesenchymal transition (EMT), is integral in development, wound healing and stem cell behaviour, and contributes pathologically to fibrosis and cancer progression. This switch in cell differentiation and behaviour is mediated by key transcription factors, including SNAIL, zinc-finger E-box-binding (ZEB) and basic helix-loop-helix transcription factors, the functions of which are finely regulated at the transcriptional, translational and post-translational levels. The reprogramming of gene expression during EMT, as well as non-transcriptional changes, are initiated and controlled by signalling pathways that respond to extracellular cues. Among these, transforming growth factor-? (TGF?) family signalling has a predominant role; however, the convergence of signalling pathways is essential for EMT. PMID:24556840

Lamouille, Samy; Xu, Jian; Derynck, Rik



Dlx1&2 and Mash1 Transcription Factors Control MGE and CGE Patterning and Differentiation through Parallel and Overlapping Pathways  

PubMed Central

Here we define the expression of ?100 transcription factors (TFs) in progenitors and neurons of the developing mouse medial and caudal ganglionic eminences, anlage of the basal ganglia and pallial interneurons. We have begun to elucidate the transcriptional hierarchy of these genes with respect to the Dlx homeodomain genes, which are essential for differentiation of most ?-aminobutyric acidergic projection neurons of the basal ganglia. This analysis identified Dlx-dependent and Dlx-independent pathways. The Dlx-independent pathway depends in part on the function of the Mash1 basic helix-loop-helix (b-HLH) TF. These analyses define core transcriptional components that differentially specify the identity and differentiation of the globus pallidus, basal telencephalon, and pallial interneurons. PMID:19386638

Long, Jason E.; Cobos, Inma; Potter, Greg B.



The emerging role of Twist proteins in hematopoietic cells and hematological malignancies  

PubMed Central

Twist1 and Twist2 (Twist1–2) are two transcription factors, members of the basic helix-loop-helix family, that have been well established as master transcriptional regulators of embryogenesis and developmental programs of mesenchymal cell lineages. Their role in oncogenesis in epithelium-derived cancer and in epithelial-to-mesenchymal transition has also been thoroughly characterized. Recently, emerging evidence also suggests a key role for Twist1–2 in the function and development of hematopoietic cells, as well as in survival and development of numerous hematological malignancies. In this review, we summarize the latest data that depict the role of Twist1–2 in monocytes, T cells and B lymphocyte activation, and in associated hematological malignancies. PMID:24769647

Merindol, N; Riquet, A; Szablewski, V; Eliaou, J-F; Puisieux, A; Bonnefoy, N



A genomewide survey of bHLH transcription factors in the coral Acropora digitifera identifies three novel orthologous families, pearl, amber, and peridot.  


Decoding the genome of the coral, Acropora digitifera, enabled us to characterize a nearly full set of 70 basic helix-loop-helix (bHLH) transcription factors in this organism. This number is comparable to 68 bHLH genes in the sea anemone, Nematostella vectensis, and larger than those in most other invertebrate metazoans. The 70 bHLH genes were assigned to 29 orthologous families previously reported. In addition, we identified three novel HLH orthologous families, which we designated pearl, amber, and peridot, increasing the number of orthologous families to 32. Pearl and amber orthologues were found in genomes and expressed sequenced tags (ESTs) of Mollusca and Annelida in addition to Cnidaria. Peridot orthologues were found in genomes and ESTs of Cephalochordata and Hemichordata in addition to Cnidaria. These three genes were likely lost in the clades of Drosophila melanogaster, Caenorhabditis elegans, and Homo sapiens during animal evolution. PMID:22419240

Gyoja, Fuki; Kawashima, Takeshi; Satoh, Nori



Flavonoids: biosynthesis, biological functions, and biotechnological applications  

PubMed Central

Flavonoids are widely distributed secondary metabolites with different metabolic functions in plants. The elucidation of the biosynthetic pathways, as well as their regulation by MYB, basic helix-loop-helix (bHLH), and WD40-type transcription factors, has allowed metabolic engineering of plants through the manipulation of the different final products with valuable applications. The present review describes the regulation of flavonoid biosynthesis, as well as the biological functions of flavonoids in plants, such as in defense against UV-B radiation and pathogen infection, nodulation, and pollen fertility. In addition, we discuss different strategies and achievements through the genetic engineering of flavonoid biosynthesis with implication in the industry and the combinatorial biosynthesis in microorganisms by the reconstruction of the pathway to obtain high amounts of specific compounds. PMID:23060891

Falcone Ferreyra, María L.; Rius, Sebastián P.; Casati, Paula



Hey1, a Mediator of Notch Signaling, Is an Androgen Receptor Corepressor  

PubMed Central

Hey1 is a member of the basic helix-loop-helix-Orange family of transcriptional repressors that mediate Notch signaling. Here we show that transcription from androgen-dependent target genes is inhibited by Hey1 and that expression of a constitutively active form of Notch is capable of repressing transactivation by the endogenous androgen receptor (AR). Our results indicate that Hey1 functions as a corepressor for AF1 in the AR, providing a mechanism for cross talk between Notch and androgen-signaling pathways. Hey1 colocalizes with AR in the epithelia of patients with benign prostatic hyperplasia, where it is found in both the cytoplasm and the nucleus. In marked contrast, we demonstrate that Hey1 is excluded from the nucleus in most human prostate cancers, raising the possibility that an abnormal Hey1 subcellular distribution may have a role in the aberrant hormonal responses observed in prostate cancer. PMID:15684393

Belandia, Borja; Powell, Sue M.; García-Pedrero, Juana M.; Walker, Marjorie M.; Bevan, Charlotte L.; Parker, Malcolm G.



Stra13 regulates satellite cell activation by antagonizing Notch signaling  

PubMed Central

Satellite cells play a critical role in skeletal muscle regeneration in response to injury. Notch signaling is vital for satellite cell activation and myogenic precursor cell expansion but inhibits myogenic differentiation. Thus, precise spatial and temporal regulation of Notch activity is necessary for efficient muscle regeneration. We report that the basic helix-loop-helix transcription factor Stra13 modulates Notch signaling in regenerating muscle. Upon injury, Stra13?/? mice exhibit increased cellular proliferation, elevated Notch signaling, a striking regeneration defect characterized by degenerated myotubes, increased mononuclear cells, and fibrosis. Stra13?/? primary myoblasts also exhibit enhanced Notch activity, increased proliferation, and defective differentiation. Inhibition of Notch signaling ex vivo and in vivo ameliorates the phenotype of Stra13?/? mutants. We demonstrate in vitro that Stra13 antagonizes Notch activity and reverses the Notch-imposed inhibition of myogenesis. Thus, Stra13 plays an important role in postnatal myogenesis by attenuating Notch signaling to reduce myoblast proliferation and promote myogenic differentiation. PMID:17502421

Sun, Hong; Li, Li; Vercherat, Cécile; Gulbagci, Neriman Tuba; Acharjee, Sujata; Li, Jiali; Chung, Teng-Kai; Thin, Tin Htwe; Taneja, Reshma



Nuclear localized protein-1 (Nulp1) increases cell death of human osteosarcoma cells and binds the X-linked inhibitor of apoptosis protein  

SciTech Connect

Nuclear localized protein-1 (Nulp1) is a recently identified gene expressed in mouse and human tissues particularly during embryonic development. Nulp1 belongs to the family of basic helix-loop-helix (bHLH) proteins that are important in development. The precise function of Nulp1 in cells is however not known. We observed that overexpression of Nulp1 induces a large increase in cell death of human osteosarcoma Saos2 cells with DNA fragmentation. In mouse N2A neuroblastoma cells Nulp1 affected cell proliferation and sensitized cells towards death induced by staurosporine. Staining using a novel antibody localized Nulp1 mainly to the cell nucleus and to some extent to the cytoplasm. Nulp1 binds the X-linked inhibitor of apoptosis protein (XIAP) and this interaction was increased during cell death. These results indicate that Nulp1 plays a role in cell death control and may influence tumor growth.

Steen, Hakan [Department of Neuroscience, Uppsala University, Biomedical Centre, Box 587, Husargatan 3, SE-75123 Uppsala (Sweden); Lindholm, Dan [Department of Neuroscience, Uppsala University, Biomedical Centre, Box 587, Husargatan 3, SE-75123 Uppsala (Sweden); Minerva Institute for Medical Research, Biomedicum Helsinki, Helsinki (Finland)], E-mail:



Citrus tristeza virus p23: a unique protein mediating key virus–host interactions  

PubMed Central

The large RNA genome of Citrus tristeza virus (CTV; ca. 20 kb) contains 12 open reading frames, with the 3?-terminal one corresponding to a protein of 209 amino acids (p23) that is expressed from an abundant subgenomic RNA. p23, an RNA-binding protein with a putative zinc-finger domain and some basic motifs, is unique to CTV because no homologs have been found in other closteroviruses, including the type species of the genus Beet yellows virus (despite both viruses having many homologous genes). Consequently, p23 might have evolved for the specific interaction of CTV with its citrus hosts. From a functional perspective p23 has been involved in many roles: (i) regulation of the asymmetrical accumulation of CTV RNA strands, (ii) induction of the seedling yellows syndrome in sour orange and grapefruit, (iii) intracellular suppression of RNA silencing, (iv) elicitation of CTV-like symptoms when expressed ectopically as a transgene in several Citrus spp., and (v) enhancement of systemic infection (and virus accumulation) in sour orange and CTV release from the phloem in p23-expressing transgenic sweet and sour orange. Moreover, transformation of Mexican lime with intron-hairpin constructs designed for the co-inactivation of p23 and the two other CTV silencing suppressors results in complete resistance against the homologous virus. From a cellular point of view, recent data indicate that p23 accumulates preferentially in the nucleolus, being the first closterovirus protein with such a subcellular localization, as well as in plasmodesmata. These major accumulation sites most likely determine some of the functional roles of p23. PMID:23653624

Flores, Ricardo; Ruiz-Ruiz, Susana; Soler, Nuria; Sánchez-Navarro, Jesús; Fagoaga, Carmen; López, Carmelo; Navarro, Luis; Moreno, Pedro; Peña, Leandro



GPS Basics  

NSDL National Science Digital Library

The Federal Aviation Administration maintains the graphically impressive Global Positioning System (GPS) Basics Web site. From the history of the global positioning system and how it works to governmental policy that controls its use, this site does a good job of explaining all facets of what GPS is about without being overly technical. Interested visitors can explore some of the other links that cover satellite navigation topics as well, such as GPS programs; a library of documents, fact sheets, press releases, and news; frequently asked questions; links; and more. Anyone interested in mapping, navigation, or similar subjects will enjoy exploring the interesting information provided on this well designed site.


Basically Acids  

NSDL National Science Digital Library

Students learn the basics of acid/base chemistry in a fun, interactive way by studying instances of acid/base chemistry found in popular films such as Harry Potter and the Prisoner of Azkaban and National Treasure. Students learn what acids, bases and indicators are and how they can be used, including invisible ink. They also learn how engineers use acids and bases every day to better our quality of life. Students' interest is piqued by the use of popular culture in the classroom.

University of Houston,


Regulation of Replication Termination in Schizosaccharomyces pombe by Reb1 Protein-Mediated Action at a Distance  

PubMed Central

The mechanisms of DNA transactions driven by long range protein-mediated inter and intra-chromosomal interactions are currently of considerable general interest. Here, we report that site-specific replication termination catalyzed by the dimeric Reb1 protein of Schizosaccharomyces. pombe at its cognate replication termini (Ter) did not occur independently at each site but was modulated by the Reb1-mediated interactions between pairs of Ter sites located either in the same or in different chromosomes. The interactions between two Ter sites in cis, placed in a mutually anti-parallel orientation, caused looping out of the intervening DNA in vitro and enhancement of fork arrest in vivo. A Ter on chromosome 2 interacted pair-wise with two Ter sites located on chromosome1 by chromosome kissing. Mutational inactivation of the major interacting Ter on chromosome1 abolished or significantly reduced fork arrest at the Ter site on chromosome 2, thereby revealing a novel mechanism of control of replication termination. PMID:20850009

Singh, Samarendra K.; Sabatinos, Sarah; Forsburg, Susan; Bastia, Deepak



Regulation of Plasmodesmatal Permeability and Stomatal Patterning by the Glycosyltransferase-Like Protein KOBITO11[W][OA  

PubMed Central

The differentiation of stomata provides a convenient model for studying pattern formation in plant tissues. Stomata formation is induced by a set of basic helix-loop-helix transcription factors and inhibited by a signal transduction pathway initiated by TOO MANY MOUTHS (TMM) and ERECTA family (ERf) receptors. The formation of a proper stomata pattern is also dependent upon the restriction of symplastic movement of basic helix-loop-helix transcription factors into neighboring cells, especially in the backgrounds where the function of the TMM/ERf signaling pathway is compromised. Here, we describe a novel mutant of KOBITO1 in Arabidopsis (Arabidopsis thaliana). The kob1-3 mutation leads to the formation of stomata clusters in the erl1 erl2 background but not in the wild type. Cell-to-cell mobility assays demonstrated an increase in intercellular protein trafficking in kob1-3, including increased diffusion of SPEECHLESS, suggesting that the formation of stomata clusters is due to an escape of cell fate-specifying factors from stomatal lineage cells. While plasmodesmatal permeability is increased in kob1-3, we did not detect drastic changes in callose accumulation at the neck regions of the plasmodesmata. Previously, KOBITO1 has been proposed to function in cellulose biosynthesis. Our data demonstrate that disruption of cellulose biosynthesis in the erl1 erl2 background does not lead to the formation of stomata clusters, indicating that cellulose biosynthesis is not a major determining factor for regulating plasmodesmatal permeability. Analysis of KOBITO1 structure suggests that it is a glycosyltransferase-like protein. KOBITO1 might be involved in a carbohydrate metabolic pathway that is essential for both cellulose biosynthesis and the regulation of plasmodesmatal permeability. PMID:22457425

Kong, Danyu; Karve, Rucha; Willet, Alaina; Chen, Ming-Kun; Oden, Jennifer; Shpak, Elena D.



Characterization of msim, a murine homologue of the Drosophila sim transcription factor  

SciTech Connect

Mutations in the Drosophila single-minded (sim) gene result in loss of precursor cells that give rise to midline cells of the embryonic central nervous system. During the course of an exon-trapping strategy aimed at identifying transcripts that contribute to the etiology and pathophysiology of Down syndrome, we identified a human exon from the Down syndrome, we identified a human exon from the Down syndrome critical region showing significantly homology to the Drosophila sim gene. Using a cross-hybridization approach, we have isolated a murine homolog of Drosophila sim gene, which we designated msim. Nucleotide and predicted amino acid sequence analyses of msim cDNA clones indicate the this gene encodes a member of the basic-helix-loop-helix class of transcription factors. The murine and Drosophila proteins share 88% residues within the basic-helix-loop helix domain, with an overall homology of 92%. In addition, the N-terminal domain of MSIM contains two PAS dimerization motifs also featured in the Drosophila sim gene product, as well as a small number of other transcription factors. Northern blot analysis of adult murine tissues revealed that the msim gene produces a single mRNA species of {approximately}4 kb expressed in a small number of tissues, with the highest levels in the kidneys and lower levels present in skeletal muscle, lung, testis, brain, and heart. In situ hybridization experiments demonstrate that msim is also expressed in early fetal development in the central nervous system and in cartilage primordia. The characteristics of the msim gene are consistent with its putative function as a transcriptional regulator. 51 refs., 6 figs., 1 tab.

Moffett, P.; Reece, M.; Pelletier, J. [McGill Univ., Quebec (Canada)] [and others] [McGill Univ., Quebec (Canada); and others



Phytochrome Induces Rapid PIF5 Phosphorylation and Degradation in Response to Red-Light Activation1[W][OA  

PubMed Central

The phytochrome (phy) family of sensory photoreceptors (phyA–phyE in Arabidopsis thaliana) induces changes in target-gene expression upon light-induced translocation to the nucleus, where certain members interact with selected members of the constitutively nuclear basic helix-loop-helix transcription factor family, such as PHYTOCHROME-INTERACTING FACTOR3 (PIF3). Previous evidence indicates that the binding of the photoactivated photoreceptor molecule to PIF3 induces rapid phosphorylation of the transcription factor in the cell prior to its degradation via the ubiqitin-proteosome system. To investigate whether this apparent primary signaling mechanism can be generalized to other phy-interacting partners, we have examined the molecular behavior of a second related phy-interacting member of the basic helix-loop-helix family, PIF5, during early deetiolation, immediately following initial exposure of dark-grown seedlings to light. The data show that red light induces very rapid phosphorylation and subsequent degradation (t1/2 < 5 min) of PIF5 via the proteosome system upon irradiation. Photobiological and genetic evidence indicates that the photoactivated phy molecule acts within 60 s to induce this phosphorylation of PIF5, and that phyA and phyB redundantly dominate this process, with phyD playing an apparently minor role. Collectively, the data support the proposal that the rapid phy-induced phosphorylation of PIF3 and PIF5 may represent the biochemical mechanism of primary signal transfer from photoactivated photoreceptor to binding partner, and that phyA and phyB (and possibly phyD) may signal to multiple, shared partners utilizing this common mechanism. PMID:17827270

Shen, Yu; Khanna, Rajnish; Carle, Christine M.; Quail, Peter H.



Sunspace basics  

SciTech Connect

Anyone who lives in a home with a sunspace will tell you that the sunspace is the most enjoyable room in the house. Many times the homeowner`s only regret is that the sunspace is not larger. Although aesthetics often drive the decision to add a sunspace or include one in a new home design, sunspaces can also provide supplemental space heating and a healthy environment for plants and people. In fact, a well-designed sunspace can provide up to 60% of a home`s winter heating requirements. This publication addresses basic elements of sunspace design; design considerations for supplemental space heating, growing plants, and use as a living space; design guidelines including siting, heat distribution, and glazing angles; and major sunspace components including glazing options, thermal mass, insulation, and climate controls. A list of sources for more information is also provided.

Not Available



Mutations Affecting the BHLHA9 DNA-Binding Domain Cause MSSD, Mesoaxial Synostotic Syndactyly with Phalangeal Reduction, Malik-Percin Type.  


Mesoaxial synostotic syndactyly, Malik-Percin type (MSSD) (syndactyly type IX) is a rare autosomal-recessive nonsyndromic digit anomaly with only two affected families reported so far. We previously showed that the trait is genetically distinct from other syndactyly types, and through autozygosity mapping we had identified a locus on chromosome 17p13.3 for this unique limb malformation. Here, we extend the number of independent pedigrees from various geographic regions segregating MSSD to a total of six. We demonstrate that three neighboring missense mutations affecting the highly conserved DNA-binding region of the basic helix-loop-helix A9 transcription factor (BHLHA9) are associated with this phenotype. Recombinant BHLHA9 generated by transient gene expression is shown to be located in the cytoplasm and the cell nucleus. Transcription factors 3, 4, and 12, members of the E protein (class I) family of helix-loop-helix transcription factors, are highlighted in yeast two-hybrid analysis as potential dimerization partners for BHLHA9. In the presence of BHLHA9, the potential of these three proteins to activate expression of an E-box-regulated target gene is reduced considerably. BHLHA9 harboring one of the three substitutions detected in MSSD-affected individuals eliminates entirely the transcription activation by these class I bHLH proteins. We conclude that by dimerizing with other bHLH protein monomers, BHLHA9 could fine tune the expression of regulatory factors governing determination of central limb mesenchyme cells, a function made impossible by altering critical amino acids in the DNA binding domain. These findings identify BHLHA9 as an essential player in the regulatory network governing limb morphogenesis in humans. PMID:25466284

Malik, Sajid; Percin, Ferda E; Bornholdt, Dorothea; Albrecht, Beate; Percesepe, Antonio; Koch, Manuela C; Landi, Antonio; Fritz, Barbara; Khan, Rizwan; Mumtaz, Sara; Akarsu, Nurten A; Grzeschik, Karl-Heinz



Three different actions of phenylglyoxal on band 3 protein-mediated anion transport across the red blood cell membrane.  


Phenylglyoxalation of the red blood cell membrane leads to three superimposed effects on band 3 protein-mediated anion equilibrium exchange as measured by means of radiosulfate: (1) a shift of the curve relating transport activity to pH towards lower pH values, possibly in combination with an increase of the maximal transport activity. This is accompanied by effect (2), the abolishment of a chloride-stimulated component of anion transport seen at low pH values. Effect (3) consists of inhibition of anion equilibrium exchange. Effect (1) prevails when phenylglyoxalation is performed at low concentrations of PG and low pH, while effect (3) predominates when exposure to PG is executed at high pH and high concentration of PG. Effect (1) is associated with a decrease of the Ki values for inhibition and binding of the reversibly acting stilbene disulfonates DNDS and DBDS. The inhibition observed as a consequence of effect (3) is linearly related to a decrease of the capacity of band 3 to combine with the stilbene disulfonate DBDS. The results are interpreted on the assumption that PG is capable of reacting with two or possibly three distinct binding sites in band 3. Reaction with one of them leads to effect (1) and, perhaps, to effect (2); reaction with the other to effect (3). The latter is possibly due to modification of Arg 730, which is homologous to Arg 748 in mouse band 3. Site-directed mutagenesis of this arginine residue showed that it is required for band 3-mediated anion transport. PMID:9042344

Gärtner, E M; Liebold, K; Legrum, B; Fasold, H; Passow, H



Investigation of cell adhesion to silica nanoparticle-decorated surfaces and the associated protein-mediated mechanisms  

NASA Astrophysics Data System (ADS)

Nanostructured materials have shown promise to improve the interface between prosthetic devices and living cells, tissues, and organs through the ability to evoke cell type-specific and size-selective functions from various cell types of in vivo importance. However, the underlying molecular level mechanisms responsible for enhancement of select cell functions on these materials are not fully understood. Silica particles of either 4, 20, or 100 nm diameters were successfully coated onto native-oxide coated silicon substrates in the range of 0 to 100% coverage by particles. The materials formulated and fabricated for the present study provide a controlled and characterized set of substrates needed for investigation of the effects of nanoscale features on the adsorption and conformation of proteins, and subsequent functions of mammalian cells that are critical to the clinical efficacy of biomaterials. The size of nanoscale surface features constituted by silica nanoparticles on native oxide-coated silicon pieces affected the adhesion of rat calvarial osteoblasts and rat skin fibroblasts differently. It was also demonstrated, for the first time, that a threshold density of nanoscale surface features is necessary to elicit size-selective, and cell type-specific, adhesion from osteoblasts or fibroblasts. Adsorption of fibronectin and vitronectin onto native oxide-coated silicon surfaces decorated with either 4, 20, or 100 nm diameter silica particles at either 25, 45, or 80% surface coverage was quantified and examined by scanning electron microscopy. Circular dichroism spectroscopy provided evidence that the secondary structures of fibronectin in the presence of either 4 or 20 nm diameter particles were similar, but fibronectin exhibited decreased beta sheet content and increased unordered structure in the presence of 100 nm particles. The secondary structure of vitronectin in the presence of silica particles exhibited similar levels of structure loss for all particle sizes examined. For the first time, this study offers insight into a molecular mechanism that is linked to nanostructured material surface feature size through quantified changes in protein structure and cell adhesion behavior. These results provide an explanation of the molecular level events occurring on nanostructured material surfaces that contribute to protein-mediated size-selective and cell type-specific responses of various cell types.

Ballard, Jake D.


Adult Basic Education Basic Computer Literacy Handbook.  

ERIC Educational Resources Information Center

This handbook, in both English and Spanish versions, is intended for use with adult basic education (ABE) students. It contains five sections of basic computer literacy activities and information about the ABE computer literacy course offered at Dona Ana Community College (DACC) in New Mexico. The handbook begins with forewords by the handbook's…

Manini, Catalina M.; Cervantes, Juan


Basics of Photometry Photometry: Basic Questions  

E-print Network

Basics of Photometry #12;Photometry: Basic Questions · How do you identify objects in your image type of object you're studying? #12;#12;#12;Topics 1. General Considerations 2. Stellar Photometry 3. Galaxy Photometry #12;I: General Considerations 1. Garbage in, garbage out... 2. Object Detection 3

Masci, Frank



ERIC Educational Resources Information Center

A comparison between PASCAL and BASIC as general purpose microprocessor languages rates PASCAL above BASIC in such points as program structure, data types, structuring methods, control structures, procedures and functions, and ease in learning. (CMV)

Mundie, David A.



Basic Facts about VHL  


Home › Patients/Caregivers › Basic Facts about VHL Basic Facts about VHL The VHL gene hijacks the major ... body. While blood vessels normally branch out like trees, in people with VHL little knots of blood ...


Basics of Weight Control  


... 2 Standard Handouts • S01 Version 5.0 The Basics of Weight Control A calorie is a unit ... beverages you drink provide energy and nutrients. The basic required nutrients are: water, carbohydrates, proteins, fats, dietary ...


CSF myelin basic protein  


CSF myelin basic protein is a test to measure the level of myelin basic protein (MBP) in the cerebrospinal fluid (CSF). The CSF ... less than 4 ng/mL of myelin basic protein in the CSF. Note: ng/mL = nanogram per ...


Mussel-inspired protein-mediated surface functionalization of electrospun nanofibers for pH-responsive drug delivery.  


pH-responsive drug delivery systems could mediate drug releasing rate by changing the pH values at specific times as per the pathophysiological need of the disease. This paper demonstrates that a mussel-inspired protein polydopamine coating can tune the loading and releasing rate of charged molecules from electrospun poly(?-caprolactone) (PCL) nanofibers in solutions with different pH values. In vitro release profiles show that the positive charged molecules release significantly faster in acidic than those in neutral and basic environments within the same incubation time. The results of fluorescein diacetate staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays show the viability of cancer cells after treatment with doxorubicin-released media at different pH values qualitatively and quantitatively, indicating that the media containing doxorubicin that were released in solutions at low pH values could kill a significantly higher number of cells than those released in solutions at high pH values. Together, the pH-responsive drug delivery systems based on polydopamine-coated PCL nanofibers could have potential application in the oral delivery of anticancer drugs for treating gastric cancer and in vaginal delivery of anti-viral drugs or anti-inflammatory drugs, which could raise their efficacy, deliver them to the specific target and minimize their toxic side effects. PMID:24287161

Jiang, J; Xie, J; Ma, B; Bartlett, D E; Xu, A; Wang, C-H



"Back to Basics" or "Forward to Basics"?  

ERIC Educational Resources Information Center

Politicians have used the promise of "back to basics in our schools" as an educational platform for some time now, possibly in recognition that this is something the general population perceives as an issue they might just vote for. In the various positions the author has held, both professional and in community service, she has been required to…

Perso, Thelma



Basic Microfluidic Lithographic  

E-print Network

CHAPTER 2 Basic Microfluidic and Soft Lithographic Techniques Sindy K.Y. Tang and George M in these devices are based on those developed for microfluidics used in biochemical anal- ysis. This chapter describes the basic ideas of microfluidics. We first summarize the materials most commonly used

Prentiss, Mara


Construction & Basic Skills.  

ERIC Educational Resources Information Center

Basic skills education has become a pressing need in the construction industry as jobs become more complex and fewer workers have needed skills. However, the construction industry lags in spending on training for entry-level workers. The Home Builders Institute (HBI) is testing a pilot basic skills program that it hopes will prove useful to the…

BCEL Newsletter for the Business and Literacy Communities, 1991



Basic Electronics I.  

ERIC Educational Resources Information Center

Designed for use in basic electronics programs, this curriculum guide is comprised of twenty-nine units of instruction in five major content areas: Orientation, Basic Principles of Electricity/Electronics, Fundamentals of Direct Current, Fundamentals of Alternating Current, and Applying for a Job. Each instructional unit includes some or all of…

Robertson, L. Paul



ERIC Educational Resources Information Center


George Washington Univ., Washington, DC. School of Education.


Basic principle of superconductivity  

E-print Network

The basic principle of superconductivity is suggested in this paper. There have been two vital wrong suggestions on the basic principle, one is the relation between superconductivity and the Bose-Einstein condensation (BEC), and another is the relation between superconductivity and pseudogap.

Tian De Cao



Solar Electric System Basics  

NSDL National Science Digital Library

The Advanced Technology Environmental and Energy Center (ATEEC) provides this sheet on the basics of solar electric systems. The document describes how photovoltaic cells work, basic energy terminology, photovoltaic materials and other related information. Users must download this resource for viewing, which requires a free log-in. There is no cost to download the item.

Gordes, Joel N.


Supernova basics Supernova types  

E-print Network

1 Supernovae · Supernova basics · Supernova types · Light Curves · SN Spectra ­ after explosion · Supernova Remnants (SNRs) · Collisional Ionization #12;2 Supernova Basics · Supernova (SN) explosions in our) · Typical SN rates ~ 1/Galaxy/century · Recent local supernovae: 1006 AD, 1054 AD (produced Crab nebula

Crenshaw, Michael


Romanian Basic Course.  

ERIC Educational Resources Information Center

The "Romanian Basic Course," consisting of 89 lesson units in eight volumes, is designed to train native English language speakers to Level 3 proficiency in comprehension, speaking, reading, and writing Romanian (based on a 1-5 scale in which Level 5 is native speaker proficiency). Volume 1, which introduces basic sentences in dialog form with…

Defense Language Inst., Washington, DC.


Basic Line Plots  

NSDL National Science Digital Library

Line plots are a useful way to display data especially change over time. In this lesson, students learn basic line plot analysis using authentic NASA wind speed data from two locations. In the extensions sections, there is an opportunity to build upon basic line plot analysis skills and opportunities for further assessment.


Basic Science Training Program.  

ERIC Educational Resources Information Center

These six learning modules were developed for Lake Michigan College's Basic Science Training Program, a workshop to develop good study skills while reviewing basic science. The first module, which was designed to provide students with the necessary skills to study efficiently, covers the following topics: time management; an overview of a study…

Brummel, Clete


Fluency with Basic Addition  

ERIC Educational Resources Information Center

Traditionally, learning basic facts has focused on rote memorization of isolated facts, typically through the use of flash cards, repeated drilling, and timed testing. However, as many experienced teachers have seen, "drill alone does not develop mastery of single-digit combinations." In contrast, a fluency approach to learning basic addition…

Garza-Kling, Gina



Ed's Basic Histology Gallery  

NSDL National Science Digital Library

This website introduces the basic concepts of histology. The site is organized by different anatomical structures and provides a tutorial, histology slices and quiz for students for each structure presented.



Basic Electricity Materials  

NSDL National Science Digital Library

This site from SpaceTEC National Aerospace Technical Education Center presents basic materials electricity. Topics include safety, metric notations, atomic structure, instruments, electrical concepts, resistor and AC circuits, power supplies, circuit protection, relays, connections, and electrostatic states.



Video Screen Capture Basics  

ERIC Educational Resources Information Center

This article is an introduction to video screen capture. Basic information of two software programs, QuickTime for Mac and BlueBerry Flashback Express for PC, are also discussed. Practical applications for video screen capture are given.

Dunbar, Laura



Basic analytic number theory  

Microsoft Academic Search

We give an informal introduction to the most basic techniques used to\\u000aevaluate moments on the critical line of the Riemann zeta-function and to find\\u000aasymptotics for sums of arithmetic functions.

David W. Farmer



Basic Nuclear Science Information  

NSDL National Science Digital Library

This webpage from the Lawrence Berkeley National Laboratory contains an overview of the basic concepts in nuclear science. Nuclear structure, particle decay, nuclear reactions, and cosmic rays are briefly discussed. The page also contains helpful pictures to illustrate the concepts.



BMP (Basic Metabolic Panel)  


... Pages On This Site Apart from the Related Tests noted above, there are no other related pages on this site. Elsewhere On The Web MedlinePlus Medical Encyclopedia: Basic metabolic panel » See all ...


Basic Electronics Tutorials  

NSDL National Science Digital Library

This site gives a number of tutorials and information to help students and instructors develop a knowledge and understanding of the basics of Electronics. Topics include amplifiers, inductors, capacitors, electromagnetism, transformers, transistors and more.

Storr, Wayne


Skywarn Spotter Convective Basics  

NSDL National Science Digital Library

The "SKYWARN® Spotter Convective Basics" module will guide users to a basic understanding of convective storms. Through three different scenarios, you will cover reporting and proper communication of local storm reports to the National Weather Service (NWS), personal safety during these events, and field identification of convective storm hazards. After completing the scenarios, you will be given the opportunity to practice identifying storm features from a spectrum of photos.




Prognostic Significance of the Lymphoblastic Leukemia-Derived Sequence 1 (LYL1) GeneExpression in Egyptian Patients with AcuteMyeloid Leukemia  

PubMed Central

Objective: Aberrant activation of transcription factor genes is the most frequent target of genetic alteration in lymphoid malignancies. The lymphoblastic leukemia-derived sequence 1 (LYL1) gene, which encodes a basic helix-loop helix, was first identified with human T-cell acute leukemia. Recent studies suggest its involvement in myeloid malignancies. We aimed to study the expression percent of oncogene LYL1 in primary and secondary high-risk myeloid leukemia and the impact on prognostic significance in those patients. Materials and Methods: Using quantitative real-time polymerase chain reaction for detection of LYL1 oncogenes, our study was carried out on 39 myeloid leukemia patients including de novo cases, myelodysplastic syndrome (MDS) with transformation, and chronic myelogenous leukemia (CML) in accelerated and blast crisis, in addition to 10 healthy individuals as the reference control. Results: LYL1 expression was increased at least 2 times compared to the controls. The highest expression of this transcription factor was observed in the MDS cases transformed to acute leukemia at 7.3±3.1, p=0.0011. LYL1 expression was found in 68.2%, 75%, and 77.8% of cases of acute myeloid leukemia, CML crisis, and MDS, respectively. Significant correlation of LYL1 overexpression with some subtypes of French-American-British classification was found. There was, for the first time, significant correlation between the blood count at diagnosis and LYL1 expression (p=0.023, 0.002, and 0.031 for white blood cells, hemoglobin, and platelets, respectively). The rate of complete remission was lower with very high levels of LYL1 expression and the risk of relapse increased with higher levels of LYL1 expression, suggesting an unfavorable prognosis for cases with enhanced expression. Conclusion: Overexpression of LYL1 is highly associated with acute myeloid leukemia and shows more expression in MDS with unfavorable prognosis in response to induction chemotherapy. These observations could signal a promising tool for a therapeutic target to basic helix–loop helix protein related to transcription factors, which may improve patient outcome in acute myeloid leukemia, MDS, and CML in blast crisis. PMID:25035669

El-Menshawy, Nadia; Shahin, Doaa; Ghazi, Hayam Fathi



Basic Principles of Ultrasound  

NSDL National Science Digital Library

Created by a team of medical professionals and health-care specialists, the main Echo Web site contains a wide range of resources dealing primarily with diagnostic ultrasounds, sonography, and the field of echocardiography. One of the most helpful of these resources is the Basic Principles of Ultrasound online course, which is available here at no cost. The course itself is divided into six different sections, along with a bibliography and FAQ area. Visitors can use the online course to learn about the basic principles of ultrasound, the basic science behind related devices and instruments, and the ways to use these devices safely. Instructors might also do well to use this website in conjunction with lectures on the subject, or as away to give students an additional resource to consult at their leisure.



The basics of ostomies.  


Basic ostomy care can be intimidating because nurses don't often see colostomies, ileostomies, or urostomies. While there are as many different ostomies as there are people who have them, there are some commonalities in the care of the stoma. These can be generalized to all stomas, regardless of the type of output. Some care, however, is specific to the placement of the stoma and the type of effluent flowing from the opening. This article will provide the gastroenterology nurse an overview of the basic features of ostomies as well as routine ostomy care. PMID:12488686

Hyland, Jo



Basics of fiber optics  

NASA Astrophysics Data System (ADS)

Fiber Optics are a medium for transmitting light. Think of having a garden hose five hundred meters long. When looking through it you are able to see 50% of the light. Now you understand the power of fiber optics. The wide variety of fiber optics presently available has advanced its use for sensing, process control and laser delivery applications. However, there is a strong need to understand fiber optics at the basic level. The focus of this paper will discuss the basics of fiber optics for step-index fibers.

Harrison, Craig D.



Genital Herpes (Beyond the Basics)  


... for sexually transmitted infections (The Basics) Patient information: Syphilis (The Basics) Patient information: Urethritis (The Basics) Prevention ... those that also produce genital ulcers, such as syphilis and chancroid. Several diagnostic tests may also be ...


Basic Soils. Revision.  

ERIC Educational Resources Information Center

This curriculum guide is designed for use in teaching a course in basic soils that is intended for college freshmen. Addressed in the individual lessons of the unit are the following topics: the way in which soil is formed, the physical properties of soil, the chemical properties of soil, the biotic properties of soil, plant-soil-water…

Montana State Univ., Bozeman. Dept. of Agricultural and Industrial Education.


MONITORING DROUGHT Basic Climatology  

E-print Network

MONITORING DROUGHT Basic Climatology Colorado Climate Center Funding provided by NOAA Sectoral Applications Research Project #12;DEFINING DROUGHT #12;First off, just what is drought? Define a tornado the same for drought #12;First off, just what is drought? Precipitation deficits? Soil moisture


Basic Media in Education.  

ERIC Educational Resources Information Center

Intended as a guide to the use of different media for use in the classroom, this document demonstrates alternative approaches that may be taken to depicting and communicating images and concepts to others. Some basic tools and materials--including a ruler, matte knife, rubber cement, stapler, felt-tip pens, paint brushes, and lettering pens--are…

Harrell, John


Teaching Basic Caregiver Skills.  

ERIC Educational Resources Information Center

This instructor's guide provides materials for a nursing skills course designed to teach basic home nursing skills to families who plan to care for a chronically ill or elderly family member at home. It may be taught by a registered nurse with knowledge of all areas or by a team, with each instructor concentrating on his/her area of expertise.…

Schenk, Susan, Ed.; Harrah, Doris, Ed.



ERIC Educational Resources Information Center




Basic Structure of Swahili.  

ERIC Educational Resources Information Center

This text in basic Swahili structure was originally written in East Africa as a teacher's guide and student's reference and was used as a basis for a course taught largely orally (with the teacher using drills he had prepared himself). The author suggests that although it is not a "linguist's book," it should prove useful to those who are teaching…

Brain, James L.


Swahili Basic Course.  

ERIC Educational Resources Information Center

This basic audiolingual course in standard Swahili appears in six volumes, Lesson Units 1-56. Units consist of a "blueprint" prefatory page outlining the phonological, morphological, and syntactic structures and new vocabulary to be presented; perception drills; Swahili dialog with cartoon guides and English translation; pattern and recombination…

Defense Language Inst., Washington, DC.


Intellectual Patent Basics  

E-print Network

Intellectual Property Patent Basics Roland W. Norris Pauley Petersen Kinne & Erickson 2800 W;Introduction Intellectual property: Patents Trademarks Copyrights Trade Secrets #12;What is a Patent? A right For the term of the patent 20 years from date of filing of earliest related patent or application #12;A

Heller, Barbara


Introduction Basic dynamics  

E-print Network

Introduction Basic dynamics The Gulf Stream The thermohaline circulation Ocean currents: some The thermohaline circulation Where is the Gulf Stream? BBC Weather Center Joe LaCasce Dept. Geosciences Ocean The thermohaline circulation Where is the Gulf Stream? Univ. Bergen news website (2011) Joe LaCasce Dept

LaCasce, Joseph H.


Microeconomic Analysis with BASIC.  

ERIC Educational Resources Information Center

Computer programs written in BASIC for the study of microeconomic analysis with special emphasis in economic decisions on price, output, and profit of a business firm are described. A very brief overview of the content of each of the 28 computer programs comprising the course is provided; four of the programs are then discussed in greater detail.…

Tom, C. F. Joseph


Adult Basic Education Curriculum.  

ERIC Educational Resources Information Center

This booklet, aimed at adult basic education students, pinpoints and summarizes a few common spelling rules to help make spelling easier, and includes a component on using the dictionary. In the text, each rule is presented with many examples. Exercises follow each spelling rule, allowing students the opportunity to apply the rule to specific…

Massachusetts Career Development Inst., Springfield.


Focus on Basics, 1998.  

ERIC Educational Resources Information Center

This volume contains the four 1998 quarterly issues of this newsletter that present best practices, current research on adult learning and literacy, and information on how research is used by adult basic education teachers, counselors, program administrators, and policy makers. The following are among the major articles included: "Power, Literacy,…

Focus on Basics, 1998



Basic Internet Software Toolkit.  

ERIC Educational Resources Information Center

Once schools are connected to the Internet, the next step is getting network workstations configured for Internet access. This article describes a basic toolkit comprising software currently available on the Internet for free or modest cost. Lists URLs for Web browser, Telnet, FTP, file decompression, portable document format (PDF) reader,…

Buchanan, Larry



Basic Pneumatics. Instructor's Guide.  

ERIC Educational Resources Information Center

This instructor's guide is designed for use by industrial vocational teachers in teaching a course on basic pneumatics. Covered in the individual units are the following topics: an introduction to pneumatics (including the operation of a service station hoist); fundamentals and physical laws; air compressors (positive displacement compressors;…

Fessehaye, Michael


Analytical Electrochemistry: Basic Concepts  

NSDL National Science Digital Library

This module focuses on the basic concepts involved in dynamic electrochemistry when the net current is not zero - the combination of mass transfer and electrochemical reactions at the interface between solids and fluids. It is at an introductory level appropriate for undergraduates in their sophomore or junior years.

Kelly, Richard S.



GPS Receiver Basics  

NSDL National Science Digital Library

Students familiarize themselves â through trial and error â with the basics of GPS receiver operation. They view a receiver's satellite visibility screen as they walk in various directions and monitor their progress on the receiver's map. Students may enter waypoints and use the GPS information to guide them back to specific locations.

Integrated Teaching And Learning Program


Czech Basic Course: Folklore.  

ERIC Educational Resources Information Center

This booklet is designed for use in the advanced phase of the Defense Language Institute's "Basic Course" in Czech. It is used in the advanced phase as a part of cultural background information. Reading selections, with vocabulary lists, include: (1) ethnography; (2) incantations and spells; (3) proverbs, sayings, and weather lore; (4) fairy tales…

Defense Language Inst., Washington, DC.


Basic Nuclear Physics.  

ERIC Educational Resources Information Center

Basic concepts of nuclear structures, radiation, nuclear reactions, and health physics are presented in this text, prepared for naval officers. Applications to the area of nuclear power are described in connection with pressurized water reactors, experimental boiling water reactors, homogeneous reactor experiments, and experimental breeder…

Bureau of Naval Personnel, Washington, DC.


Networks: The Basics.  

ERIC Educational Resources Information Center

Introduces the information superhighway (the Internet), and presents a guide to navigating it. Offers basic instruction on obtaining and learning to use network accounts; locating addresses using Archie and Wide Area Information Server; retrieving information using file transfer protocol; utilizing Gopher to find and retrieve; browsing the World…

Lomarcan, Diana L.



Uranium: a basic evaluation  

Microsoft Academic Search

All energy sources and technologies, including uranium and the nuclear industry, are needed to provide power. Public misunderstanding of the nature of uranium and how it works as a fuel may jeopardize nuclear energy as a major option. Basic chemical facts about uranium ore and uranium fuel technology are presented. Some of the major policy decisions that must be made





ERIC Educational Resources Information Center




Hindi Basic Reader.  

ERIC Educational Resources Information Center

This reader is intended to accompany the Basic Course in Spoken Hindi. Following an outline of the Devanagari script, 20 lessons are presented. Each consists of a reading selection, several illustrative sentences in English and Hindi, and a series of questions. Most of the reading selections were adapted from the magazine "Bal-Bharati." (RM)

Harter, J. Martin; And Others


Assessing Basic Fact Fluency  

ERIC Educational Resources Information Center

In this article, the authors share a variety of ways to formatively assess basic fact fluency. The define fluency, raise some issues related to timed testing, and then share a collection of classroom-tested ideas for authentic fact fluency assessment. This article encourages teachers to try a variety of alternative assessments from this sampling,…

Kling, Gina; Bay-Williams, Jennifer M.




E-print Network

the relation of heat to other forms of energy and review the energy balance. We then present the three basic transfer are related to each other, Distinguish thermal energy from other forms of energy, and heat transfer from other forms of energy transfer, Perform general energy balances as well as surface energy

Kostic, Milivoje M.


Turkish Basic Course.  

ERIC Educational Resources Information Center

These 14 volumes of the Defense Language Institute's basic course in Turkish consist of 112 lesson units designed to train native English language speakers to Level 3 proficiency in comprehending, speaking, reading, and writing Turkish. (Native-speaker fluency is Level 5.) An introduction to the sound system, vowel harmony, and syllable division…

Defense Language Inst., Washington, DC.


Basic Electricity. Part 1.  

ERIC Educational Resources Information Center

A primarily illustrated introduction to the basics of electricity is presented in this guide, the first of a set of four designed for the student interested in a vocation in electrical work. This guide is intended for the first-year student and provides mostly diagrams with accompanying defintions/information in three units, each covering one of…

Kilmer, Donald C.


Basic Engineer Equipment Mechanic.  

ERIC Educational Resources Information Center

This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by basic engineer equipment mechanics. Addressed in the four individual units of the course are the following topics: mechanics and their tools (mechanics, hand tools, and power…

Marine Corps Inst., Washington, DC.


Cloud Physics: The Basics  

NSDL National Science Digital Library

This website from the Oklahoma Weather Modification Program encourages students to initiate a debate on the controversy surrounding the issue of inducing or enhancing precipitation. The exercise describes the two basic tenets of cloud seeding: the Static Phase Hypothesis and the Dynamic Phase Hypothesis. Also provided are links to a weather and climate glossary and further information about clouds and precipitation.

Klatt, Michael L.


Backbone dynamics of sequence specific recognition and binding by the yeast Pho4 bHLH domain probed by NMR.  

PubMed Central

Backbone dynamics of the basic/helix-loop-helix domain of Pho4 from Saccharomyces cerevisae have been probed by NMR techniques, in the absence of DNA, nonspecifically bound to DNA and bound to cognate DNA. Alpha proton chemical shift indices and nuclear Overhauser effect patterns were used to elucidate the secondary structure in these states. These secondary structures are compared to the co-crystal complex of Pho4 bound to a cognate DNA sequence (Shimizu T. Toumoto A, Ihara K, Shimizu M, Kyogou Y, Ogawa N, Oshima Y, Hakoshima T, 1997, EMBO J 15: 4689-4697). The dynamic information provides insight into the nature of this DNA binding domain as it progresses from free in solution to a specifically bound DNA complex. Relative to the unbound form, we show that formation of either the nonspecific and cognate DNA bound complexes involves a large change in conformation and backbone dynamics of the basic region. The nonspecific and cognate complexes, however, have nearly identical secondary structure and backbone dynamics. We also present evidence for conformational flexibility at a highly conserved glutamate basic region residue. These results are discussed in relation to the mechanism of sequence specific recognition and binding. PMID:11206057

Cave, J. W.; Kremer, W.; Wemmer, D. E.



Synergistic interactions of lipids and myelin basic protein  

NASA Astrophysics Data System (ADS)

This report describes force measurements and atomic force microscope imaging of lipid-protein interactions that determine the structure of a model membrane system that closely mimics the myelin sheath. Our results suggest that noncovalent, mainly electrostatic and hydrophobic, interactions are responsible for the multilamellar structure and stability of myelin. We find that myelin basic protein acts as a lipid coupler between two apposed bilayers and as a lipid "hole-filler," effectively preventing defect holes from developing. From our protein-mediated-adhesion and force-distance measurements, we develop a simple quantitative model that gives a reasonably accurate picture of the molecular mechanism and adhesion of bilayer-bridging proteins by means of noncovalent interactions. The results and model indicate that optimum myelin adhesion and stability depend on the difference between, rather than the product of, the opposite charges on the lipid bilayers and myelin basic protein, as well as on the repulsive forces associated with membrane fluidity, and that small changes in any of these parameters away from the synergistically optimum values can lead to large changes in the adhesion or even its total elimination. Our results also show that the often-asked question of which membrane species, the lipids or the proteins, are the "important ones" may be misplaced. Both components work synergistically to provide the adhesion and overall structure. A better appreciation of the mechanism of this synergy may allow for a better understanding of stacked and especially myelin membrane structures and may lead to better treatments for demyelinating diseases such as multiple sclerosis. lipid-protein interactions | myelin membrane structure | membrane adhesion | membrane regeneration/healing | demyelinating diseases

Hu, Yufang; Doudevski, Ivo; Wood, Denise; Moscarello, Mario; Husted, Cynthia; Genain, Claude; Zasadzinski, Joseph A.; Israelachvili, Jacob



Basics of Cell Culture  

NSDL National Science Digital Library

These manuals are used in the Stem Cell Culture Course at City College of San Francisco. This course is about general mammalian cell culture techniques but includes a laboratory exercise using stem cells (takes 3 weeks to complete). The course is taught to high school students but the materials are also used for college students. Laboratory exercises provide instruction in basic techniques of routine cell culture using common cell lines before progressing to differentiation of mouse embryonic stem cells. Photographs and explanations of common equipment (laminar flow hood, inverted microscope, etc.) and reagents are provided. Laboratory exercises include the following: Basic Aseptic Technique; Media Preparation; Plating cells from frozen stock; Cell counting and plating; Survival assay (UV); Live Cell Identification; Transfection; Freezing cells; Stem cell differentiation. A student lab manual and an instructor manual are provided.

Afshar, Golnar


Population: Basic Statistics  

NSDL National Science Digital Library

This lesson reinforces the idea that Earth's population, including the population of the United States, is gowing at a dramatic rate. It discusses some of the basics of demography, the study of population and its changes, and introduces key terms used to describe a population. The lesson inlcudes an activity in which students use an online reference to look up some population statistics and answer questions related to them.

Rhinehart, Ken; Pratte, John


Basic plasma physics II  

Microsoft Academic Search

The basic physics of classical ideal plasmas is presented in reviews of recent theoretical and experimental investigations, with an emphasis on nonlinear interactions violating the assumptions of weak turbulence. Topics examined include Kolmogorov spectra, parametric instabilities in magnetoactive plasmas, collapse and self-focusing of Langmuir waves, collective dissipation and transport, spontaneous reconnection of magnetic-field lines in a collisionless plasma, collective-beam\\/plasma interaction,

A. A. Galeev; R. N. Sudan



Basic Liquid Chromatography  

NSDL National Science Digital Library

The online textbook, Basic Liquid Chromatography, is provided by Dr. Yuri Kazakevich and Dr. Harold McNair of Seton Hall University. For those needing review or an introduction to the subject, the well designed and easily read document contains a wealth of information. Sections include an introduction, instrumentation, detectors, theory, adsorbents, reversed phase, gel permeation chromatography, column selection, pH effect, and even an online short course.

Kazakevich, Yuri.



The Basic Anaesthesia Machine  

PubMed Central

After WTG Morton's first public demonstration in 1846 of use of ether as an anaesthetic agent, for many years anaesthesiologists did not require a machine to deliver anaesthesia to the patients. After the introduction of oxygen and nitrous oxide in the form of compressed gases in cylinders, there was a necessity for mounting these cylinders on a metal frame. This stimulated many people to attempt to construct the anaesthesia machine. HEG Boyle in the year 1917 modified the Gwathmey's machine and this became popular as Boyle anaesthesia machine. Though a lot of changes have been made for the original Boyle machine still the basic structure remains the same. All the subsequent changes which have been brought are mainly to improve the safety of the patients. Knowing the details of the basic machine will make the trainee to understand the additional improvements. It is also important for every practicing anaesthesiologist to have a thorough knowledge of the basic anaesthesia machine for safe conduct of anaesthesia. PMID:24249876

Gurudatt, CL



Wimba Voice Design Basics Worksheet  

E-print Network

Wimba Voice Design Basics Worksheet © 2008 Wimba, Inc. Wimba Voice: Design Basics Worksheet-playing activities · Private communication for instructor to students #12;Wimba Voice Design Basics Worksheet © 2008 Wimba, Inc. Wimba Voice: Design Basics Worksheet Material License - Free Strong foundation will support

Xu, Shouhuai


Mbh 1: a novel gelsolin/severin-related protein which binds actin in vitro and exhibits nuclear localization in vivo.  

PubMed Central

We describe the characterization of a novel cDNA, mbh1 (myc basic motif homolog-1), which was found during a search for candidate factors which might interact with the c-Myc oncoprotein. Embedded within the amino acid sequence encoded by mbh1 is a region distantly related to the basic/helix-loop-helix (B/HLH) DNA-binding motif and a potential nuclear localization signal. Mbh1 encodes a polypeptide structurally similar to the actin-severing proteins gelsolin and severin. Translation of mbh1 RNA in rabbit reticulocyte extracts produces an approximately 45 kd protein capable of binding actin-coupled agarose beads in vitro in a Ca2(+)-dependent manner. Antiserum raised to a trpE/mbh1 bacterial fusion protein recognizes an approximately 45 kb protein in murine 3T3 fibroblasts, suggesting that the cDNA encodes the complete Mbh1 protein. Examination of Mbh1 localization in 3T3 fibroblasts by indirect immunofluorescence reveals a larger cell population showing diffuse staining, and a smaller population exhibiting a distinct nuclear stain. Western analysis corroborates this intracellular localization and indicates that total cellular levels and localization of Mbh1 are not affected by the cell growth state. The data suggest that Mbh1 may play a role in regulating cytoplasmic and/or nuclear architecture through potential interactions with actin. Images PMID:1849072

Prendergast, G C; Ziff, E B



Developmental expression of COE across the Metazoa supports a conserved role in neuronal cell-type specification and mesodermal development  

PubMed Central

The transcription factor COE (collier/olfactory-1/early B cell factor) is an unusual basic helix–loop–helix transcription factor as it lacks a basic domain and is maintained as a single copy gene in the genomes of all currently analysed non-vertebrate Metazoan genomes. Given the unique features of the COE gene, its proposed ancestral role in the specification of chemosensory neurons and the wealth of functional data from vertebrates and Drosophila, the evolutionary history of the COE gene can be readily investigated. We have examined the ways in which COE expression has diversified among the Metazoa by analysing its expression from representatives of four disparate invertebrate phyla: Ctenophora (Mnemiopsis leidyi); Mollusca (Haliotis asinina); Annelida (Capitella teleta and Chaetopterus) and Echinodermata (Strongylocentrotus purpuratus). In addition, we have studied COE function with knockdown experiments in S. purpuratus, which indicate that COE is likely to be involved in repressing serotonergic cell fate in the apical ganglion of dipleurula larvae. These analyses suggest that COE has played an important role in the evolution of ectodermally derived tissues (likely primarily nervous tissues) and mesodermally derived tissues. Our results provide a broad evolutionary foundation from which further studies aimed at the functional characterisation and evolution of COE can be investigated. Electronic supplementary material The online version of this article (doi:10.1007/s00427-010-0343-3) contains supplementary material, which is available to authorized users. PMID:21069538

Meyer, Néva P.; Seaver, Elaine; Pang, Kevin; McDougall, Carmel; Moy, Vanessa N.; Gordon, Kacy; Degnan, Bernard M.; Martindale, Mark Q.; Burke, Robert D.; Peterson, Kevin J.



Arabidopsis bZIP16 transcription factor integrates light and hormone signaling pathways to regulate early seedling development.  


Transcriptomic adjustment plays an important role in Arabidopsis thaliana seed germination and deetiolation in response to environmental light signals. The G-box cis-element is commonly present in promoters of genes that respond positively or negatively to the light signal. In pursuing additional transcriptional regulators that modulate light-mediated transcriptome changes, we identified bZIP16, a basic region/Leu zipper motif transcription factor, by G-box DNA affinity chromatography. We confirmed that bZIP16 has G-box-specific binding activity. Analysis of bzip16 mutants revealed that bZIP16 is a negative regulator in light-mediated inhibition of cell elongation but a positive regulator in light-regulated seed germination. Transcriptome analysis supported that bZIP16 is primarily a transcriptional repressor regulating light-, gibberellic acid (GA)-, and abscisic acid (ABA)-responsive genes. Chromatin immunoprecipitation analysis revealed that bZIP16 could directly target ABA-responsive genes and RGA-like2, a DELLA gene in the GA signaling pathway. bZIP16 could also indirectly repress the expression of phytochrome interacting factoR3-like5, which encodes a basic helix-loop-helix protein coordinating hormone responses during seed germination. By repressing the expression of these genes, bZIP16 functions to promote seed germination and hypocotyl elongation during the early stages of Arabidopsis seedling development. PMID:23104829

Hsieh, Wen-Ping; Hsieh, Hsu-Liang; Wu, Shu-Hsing



Developmental expression of COE across the Metazoa supports a conserved role in neuronal cell-type specification and mesodermal development.  


The transcription factor COE (collier/olfactory-1/early B cell factor) is an unusual basic helix-loop-helix transcription factor as it lacks a basic domain and is maintained as a single copy gene in the genomes of all currently analysed non-vertebrate Metazoan genomes. Given the unique features of the COE gene, its proposed ancestral role in the specification of chemosensory neurons and the wealth of functional data from vertebrates and Drosophila, the evolutionary history of the COE gene can be readily investigated. We have examined the ways in which COE expression has diversified among the Metazoa by analysing its expression from representatives of four disparate invertebrate phyla: Ctenophora (Mnemiopsis leidyi); Mollusca (Haliotis asinina); Annelida (Capitella teleta and Chaetopterus) and Echinodermata (Strongylocentrotus purpuratus). In addition, we have studied COE function with knockdown experiments in S. purpuratus, which indicate that COE is likely to be involved in repressing serotonergic cell fate in the apical ganglion of dipleurula larvae. These analyses suggest that COE has played an important role in the evolution of ectodermally derived tissues (likely primarily nervous tissues) and mesodermally derived tissues. Our results provide a broad evolutionary foundation from which further studies aimed at the functional characterisation and evolution of COE can be investigated. PMID:21069538

Jackson, Daniel J; Meyer, Néva P; Seaver, Elaine; Pang, Kevin; McDougall, Carmel; Moy, Vanessa N; Gordon, Kacy; Degnan, Bernard M; Martindale, Mark Q; Burke, Robert D; Peterson, Kevin J



Protective Effect of Electroacupuncture on Neural Myelin Sheaths is Mediated via Promotion of Oligodendrocyte Proliferation and Inhibition of Oligodendrocyte Death After Compressed Spinal Cord Injury.  


Electroacupuncture (EA) has been used worldwide to treat demyelinating diseases, but its therapeutic mechanism is poorly understood. In this study, a custom-designed model of compressed spinal cord injury (CSCI) was used to induce demyelination. Zusanli (ST36) and Taixi (KI3) acupoints of adult rats were stimulated by EA to demonstrate its protective effect. At 14 days after EA, both locomotor skills and ultrastructural features of myelin sheath were significantly improved. Phenotypes of proliferating cells were identified by double immunolabeling of 5-ethynyl-2'-deoxyuridine with antibodies to cell markers: NG2 [oligodendrocyte precursor cell (OPC) marker], 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase) (oligodendrocyte marker), and glial fibrillary acidic protein (GFAP) (astrocyte marker). EA enhanced the proliferation of OPCs and CNPase, as well as the differentiation of OPCs by promoting Olig2 (the basic helix-loop-helix protein) and attenuating Id2 (the inhibitor of DNA binding 2). EA could also improve myelin basic protein (MBP) and protect existing oligodendrocytes from apoptosis by inhibiting caspase-12 (a representative of endoplasmic reticulum stress) and cytochrome c (an apoptotic factor and hallmark of mitochondria). Therefore, our results indicate that the protective effect of EA on neural myelin sheaths is mediated via promotion of oligodendrocyte proliferation and inhibition of oligodendrocyte death after CSCI. PMID:25465241

Huang, Siqin; Tang, Chenglin; Sun, Shanquan; Cao, Wenfu; Qi, Wei; Xu, Jin; Huang, Juan; Lu, Weitian; Liu, Qian; Gong, Biao; Zhang, Yi; Jiang, Jin



The Basics of MRI  

NSDL National Science Digital Library

The Basics of MRI is a hypertextbook by Dr. Joseph Hornak of the Rochester Institute of Technology that focuses on the mathematics and physics of magnetic resonance imaging. "Exponential Functions," "Differentials and Integrals," and "Coordinate Transformation" are just a few of the mathematical topics discussed. The physics behind MRI is broken down into the following chapters: "Spin Physics," "NMR Spectroscopy," "Fourier Transforms," "Imaging Principles," and "Fourier Transform Imaging Principles." Hornak has also included a multitude of information on imaging techniques, presentation, and hardware. Those concerned with what occurs during a MRI exam, rather than the math and physics of MRI, will want to consult the chapter entitled "Your MRI Exam."

Hornak, Joseph P.


Basic Financial Statements  

NSDL National Science Digital Library

Dr. Sharon Garrison of the University of Arizona created this basic overview of financial statements for students. Concepts covered in this tutorial include the accounting equation, double entry accounting, debits and credits, balance sheets and income statements. The resources on this site are designed to equip users with the ability identify specific components of a balance sheet and what it says about a company, and the knowledge to put together an income statement. The information on financial statements introduces accounting students to general concepts, and serves as an excellent reference resource for finance fundamentals.

Garrison, Sharon H.



Basics of spectropolarimetry  

NASA Astrophysics Data System (ADS)

Many astronomical sources of radiation emit polarised radiation, for example because of the presence of a disk which produces linear polarisation by scattering some photospheric radiation, or because of the presence of a magnetic field, which leads to circular and sometimes linear polarisation of spectral line profiles. Measuring the wavelength dependence of the polarisation of radiation from such sources can reveal valuable and interesting constraints on the nature of the objects observed. This paper summarises the basic ideas of spectropolarimetry and describes some of the information it can provide.

Landstreet, John D.



Basic Hitchhiker Payload Requirements  

NASA Technical Reports Server (NTRS)

This document lists the requirements for the NMSU Hitchhiker experiment payload that were developed as part of the EE 498/499 Capstone Design class during the 1999-2000 academic year. This document is used to describe the system needs as described in the mission document. The requirements listed here are those primarily used to generate the basic electronic and data processing requirements developed in the class design document. The needs of the experiment components are more fully described in the draft NASA hitchhiker customer requirements document. Many of the details for the overall payload are given in full detail in the NASA hitchhiker documentation.

Horan, Stephen



Clean Energy Basics  

NSDL National Science Digital Library

From the National Renewable Energy Laboratory, the Clean Energy Basics Website amounts to a good primer on renewable energy. The four sections of the site are each introduced by a question (What is renewable energy? Why is renewable energy important? Why is energy efficiency important? What does clean energy have to do with me?). The What is renewable energy? section is further divided into topics including information and links for solar energy, wind energy, bioenergy, geothermal energy, hydropower, and ocean energy. While many of the links highlighted within the text are internal, there are quite a few links to reliable external sites as well.


Basic Coastal Engineering  

NASA Astrophysics Data System (ADS)

This text/reference is the only one of its kind to offer the basics on surface wave mechanics and coastal processes along with the fundamentals of coastal engineering analysis and design. It also provides the necessary background from which the reader can pursue a more advanced study of the various theoretical and applied aspects of coastal hydromechanics and coastal engineering design. This classic text/reference offers senior and beginning post-graduate students in civil and mechanical engineering or the physical and environmental sciences a well-rounded introduction to coastal engineering.

Sorensen, Robert M.


Career Basics Booklet  

NSDL National Science Digital Library

Struggling with your next career step? Science Careers' editorial team brings you "Career Basics: Advice and Resources for Scientists." The booklet provides advice and help on preparing CVs and resumes, writing grants and scientific papers, networking, and much more. Read each article in the booklet online, or download each chapter or the entire booklet as a PDF. All for free. It is one more tool Science Careers provides to help you jump-start your career, be it in academia or outside the ivory tower!

Science Careers (Science)



Basic and clinical immunology  

NASA Technical Reports Server (NTRS)

Progress in immunology continues to grow exponentially every year. New applications of this knowledge are being developed for a broad range of clinical conditions. Conversely, the study of primary and secondary immunodeficiencies is helping to elucidate the intricate mechanisms of the immune system. We have selected a few of the most significant contributions to the fields of basic and clinical immunology published between October 2001 and October 2002. Our choice of topics in basic immunology included the description of T-bet as a determinant factor for T(H)1 differentiation, the role of the activation-induced cytosine deaminase gene in B-cell development, the characterization of CD4(+)CD25(+) regulatory T cells, and the use of dynamic imaging to study MHC class II transport and T-cell and dendritic cell membrane interactions. Articles related to clinical immunology that were selected for review include the description of immunodeficiency caused by caspase 8 deficiency; a case series report on X-linked agammaglobulinemia; the mechanism of action, efficacy, and complications of intravenous immunoglobulin; mechanisms of autoimmunity diseases; and advances in HIV pathogenesis and vaccine development. We also reviewed two articles that explore the possible alterations of the immune system caused by spaceflights, a new field with increasing importance as human space expeditions become a reality in the 21st century.

Chinen, Javier; Shearer, William T.



Basic space payload fastener  

NASA Technical Reports Server (NTRS)

A new basic space fastener has been developed and tested by the GSFC. The purposes of this fastener are to permit assembly and servicing in space by astronauts and/or robots and to facilitate qualification of payloads on Earth prior to launch by saving time and money during the systems integration and component testing and qualification processes. The space fastener is a rework of the basic machine screw such that crossthreading is impossible; it is self-locking and will not work its way out during launch (vibration proof); it will not wear out despite repeated use; it occupies a small foot print which is comparable to its machine screw equivalent, and it provides force and exhibits strength comparable to its machine screw equivalent. Construction is ultra-simple and cost effective and the principle is applicable across the full range of screw sizes ranging from a #10 screw to 2.5 cm (1 in) or more. In this paper, the fastener principles of operation will be discussed along with test results and construction details. The new fastener also has considerable potential in the commercial sector. A few promising applications will be presented.

Vranish, J. M.; Gorevan, Stephen



Mga is essential for the survival of pluripotent cells during peri-implantation development.  


The maintenance and control of pluripotency is of great interest in stem cell biology. The dual specificity T-box/basic-helix-loop-helix-zipper transcription factor Mga is expressed in the pluripotent cells of the inner cell mass (ICM) and epiblast of the peri-implantation mouse embryo, but its function has not been investigated previously. Here, we use a loss-of-function allele and RNA knockdown to demonstrate that Mga depletion leads to the death of proliferating pluripotent ICM cells in vivo and in vitro, and the death of embryonic stem cells (ESCs) in vitro. Additionally, quiescent pluripotent cells lacking Mga are lost during embryonic diapause. Expression of Odc1, the rate-limiting enzyme in the conversion of ornithine into putrescine in the synthesis of polyamines, is reduced in Mga mutant cells, and the survival of mutant ICM cells as well as ESCs is rescued in culture by the addition of exogenous putrescine. These results suggest a mechanism whereby Mga influences pluripotent cell survival through regulation of the polyamine pool in pluripotent cells of the embryo, whether they are in a proliferative or quiescent state. PMID:25516968

Washkowitz, Andrew J; Schall, Caroline; Zhang, Kun; Wurst, Wolfgang; Floss, Thomas; Mager, Jesse; Papaioannou, Virginia E



The ABORTED MICROSPORES Regulatory Network Is Required for Postmeiotic Male Reproductive Development in Arabidopsis thaliana[W][OA  

PubMed Central

The Arabidopsis thaliana ABORTED MICROSPORES (AMS) gene encodes a basic helix-loop-helix (bHLH) transcription factor that is required for tapetal cell development and postmeiotic microspore formation. However, the regulatory role of AMS in anther and pollen development has not been fully defined. Here, we show by microarray analysis that the expression of 549 anther-expressed genes was altered in ams buds and that these genes are associated with tapetal function and pollen wall formation. We demonstrate that AMS has the ability to bind in vitro to DNA containing a 6-bp consensus motif, CANNTG. Moreover, 13 genes involved in transportation of lipids, oligopeptides, and ions, fatty acid synthesis and metabolism, flavonol accumulation, substrate oxidation, methyl-modification, and pectin dynamics were identified as direct targets of AMS by chromatin immunoprecipitation. The functional importance of the AMS regulatory pathway was further demonstrated by analysis of an insertional mutant of one of these downstream AMS targets, an ABC transporter, White-Brown Complex homolog, which fails to undergo pollen development and is male sterile. Yeast two-hybrid screens and pull-down assays revealed that AMS has the ability to interact with two bHLH proteins (AtbHLH089 and AtbHLH091) and the ATA20 protein. These results provide insight into the regulatory role of the AMS network during anther development. PMID:20118226

Xu, Jie; Yang, Caiyun; Yuan, Zheng; Zhang, Dasheng; Gondwe, Martha Y.; Ding, Zhiwen; Liang, Wanqi; Zhang, Dabing; Wilson, Zoe A.



ARNT2 mutation causes hypopituitarism, post-natal microcephaly, visual and renal anomalies  

PubMed Central

We describe a previously unreported syndrome characterized by secondary (post-natal) microcephaly with fronto-temporal lobe hypoplasia, multiple pituitary hormone deficiency, seizures, severe visual impairment and abnormalities of the kidneys and urinary tract in a highly consanguineous family with six affected children. Homozygosity mapping and exome sequencing revealed a novel homozygous frameshift mutation in the basic helix-loop-helix transcription factor gene ARNT2 (c.1373_1374dupTC) in affected individuals. This mutation results in absence of detectable levels of ARNT2 transcript and protein from patient fibroblasts compared with controls, consistent with nonsense-mediated decay of the mutant transcript and loss of ARNT2 function. We also show expression of ARNT2 within the central nervous system, including the hypothalamus, as well as the renal tract during human embryonic development. The progressive neurological abnormalities, congenital hypopituitarism and post-retinal visual pathway dysfunction in affected individuals demonstrates for the first time the essential role of ARNT2 in the development of the hypothalamo-pituitary axis, post-natal brain growth, and visual and renal function in humans. PMID:24022475

Webb, Emma A.; AlMutair, Angham; Kelberman, Daniel; Bacchelli, Chiara; Chanudet, Estelle; Lescai, Francesco; Andoniadou, Cynthia L.; Banyan, Abdul; Alsawaid, Al; Alrifai, Muhammad T.; Alahmesh, Mohammed A.; Balwi, M.; Mousavy-Gharavy, Seyedeh N.; Lukovic, Biljana; Burke, Derek; McCabe, Mark J.; Kasia, Tessa; Kleta, Robert; Stupka, Elia; Beales, Philip L.; Thompson, Dorothy A.; Chong, W. Kling; Alkuraya, Fowzan S.; Martinez-Barbera, Juan-Pedro; Sowden, Jane C.



Twist-2 Controls Myeloid Lineage Development and Function  

PubMed Central

Basic helix-loop-helix (bHLH) transcription factors play critical roles in lymphoid and erythroid development; however, little is known about their role in myeloid lineage development. In this study, we identify the bHLH transcription factor Twist-2 as a key negative regulator of myeloid lineage development, as manifested by marked increases in mature myeloid populations of macrophages, neutrophils, and basophils in Twist-2–deficient mice. Mechanistic studies demonstrate that Twist-2 inhibits the proliferation as well as differentiation of granulocyte macrophage progenitors (GMP) by interacting with and inhibiting the transcription factors Runx1 and C/EBP?. Moreover, Twist-2 was found to have a contrasting effect on cytokine production: inhibiting the production of proinflammatory cytokines such as interleukin-12 (IL-12) and interferon-? (IFN?) while promoting the regulatory cytokine IL-10 by myeloid cells. The data from further analyses suggest that Twist-2 activates the transcription factor c-Maf, leading to IL-10 expression. In addition, Twist-2 was found to be essential for endotoxin tolerance. Thus, this study reveals the critical role of Twist-2 in regulating the development of myeloid lineages, as well as the function and inflammatory responses of mature myeloid cells. PMID:19090621

Sharabi, Andrew B; Aldrich, Melissa; Sosic, Drazen; Olson, Eric N; Friedman, Alan D; Lee, Sung-Hyung; Chen, Si-Yi



Nato3 integrates with the Shh-Foxa2 transcriptional network regulating the differentiation of midbrain dopaminergic neurons.  


Mesencephalic dopaminergic (mesDA) neurons originate from the floor plate of the midbrain, a transient embryonic organizing center located at the ventral-most midline. Since the loss of mesDA leads to Parkinson's disease, the molecular mechanisms controlling the genesis and differentiation of dopaminergic progenitors are extensively studied and the identification and characterization of new genes is of interest. Here, we show that the expression of the basic helix-loop-helix transcription factor Nato3 (Ferd3l) increases in parallel to the differentiation of SN4741 dopaminergic cells in vitro. Nato3 transcription is directly regulated by the transcription factor Foxa2, a target and effector of the Sonic hedgehog (Shh) signaling cascade. Moreover, pharmacological inhibition of Shh signaling downregulated the expression of Nato3, thus defining Nato3 as a novel component of one of the major pathways controlling cell patterning and generation of mesDA. Furthermore, we show that Nato3 regulated Shh and Foxa2 through a novel feed-backward loop. Up- and downregulation of Nato3 further affected the transcription of Nurr1, implicated in the genesis of mesDA, but not of TH. Taken together, these data shed new light on the transcriptional networks controlling the generation of mesDA and may be utilized in the efforts to direct stem cells towards a dopaminergic fate. PMID:23254923

Nissim-Eliraz, Einat; Zisman, Sophie; Schatz, Omri; Ben-Arie, Nissim



Arabidopsis HFR1 Is a Potential Nuclear Substrate Regulated by the Xanthomonas Type III Effector XopDXcc8004  

PubMed Central

XopDXcc8004, a type III effector of Xanthomonas campestris pv. campestris (Xcc) 8004, is considered a shorter version of the XopD, which lacks the N-terminal domain. To understand the functions of XopDXcc8004, in planta, a transgenic approach combined with inducible promoter to analyze the effects of XopDXcc8004 in Arabidopsis was done. Here, the expression of XopDXcc8004, in Arabidopsis elicited the accumulation of host defense-response genes. These molecular changes were dependent on salicylic acid and correlated with lesion-mimic phenotypes observed in XVE::XopDXcc8004 transgenic plants. Moreover, XopDXcc8004 was able to desumoylate HFR1, a basic helix-loop-helix transcription factor involved in photomorphogenesis, through SUMO protease activity. Interestingly, the hfr1-201 mutant increased the expression of host defense-response genes and displayed a resistance phenotype to Xcc8004. These data suggest that HFR1 is involved in plant innate immunity and is potentially regulated by XopDXcc8004. PMID:25647296

Tan, Choon Meng; Li, Meng-Ying; Yang, Pei-Yun; Chang, Shu Heng; Ho, Yi-Ping; Lin, Hong; Deng, Wen-Ling; Yang, Jun-Yi



Tomato Male sterile 1035 is essential for pollen development and meiosis in anthers.  


Male fertility in flowering plants depends on proper cellular differentiation in anthers. Meiosis and tapetum development are particularly important processes in pollen production. In this study, we showed that the tomato male sterile (ms10 (35) ) mutant of cultivated tomato (Solanum lycopersicum) exhibited dysfunctional meiosis and an abnormal tapetum during anther development, resulting in no pollen production. We demonstrated that Ms10 (35) encodes a basic helix-loop-helix transcription factor that is specifically expressed in meiocyte and tapetal tissue from pre-meiotic to tetrad stages. Transgenic expression of the Ms10 (35) gene from its native promoter complemented the male sterility of the ms10 (35) mutant. In addition, RNA-sequencing-based transcriptome analysis revealed that Ms10 (35) regulates 246 genes involved in anther development processes such as meiosis, tapetum development, cell-wall degradation, pollen wall formation, transport, and lipid metabolism. Our results indicate that Ms10 (35) plays key roles in regulating both meiosis and programmed cell death of the tapetum during microsporogenesis. PMID:25262227

Jeong, Hee-Jin; Kang, Jin-Ho; Zhao, Meiai; Kwon, Jin-Kyung; Choi, Hak-Soon; Bae, Jung Hwan; Lee, Hyun-Ah; Joung, Young-Hee; Choi, Doil; Kang, Byoung-Cheorl



Bhlhb5 is Required for the Subtype Development of Retinal Amacrine and Bipolar Cells in Mice  

PubMed Central

Background BHLHB5, an OLIG-related basic helix-loop-helix transcription factor, is required for the development of a subset of gamma-amino butyric acid–releasing (GABAergic) amacrine cells and OFF-cone bipolar (CB) cells in mouse retinas. In order to determine BHLHB5’s functional mechanism in retinogenesis, we used the Cre-loxP recombination system to genetically trace the lineage of BHLHB5+ cells in normal and Bhlhb5-null retinas. The Bhlhb5-Cre knock-in allele was used to activate the constitutive expression of a GFP reporter in the Bhlhb5-expressing cells, and the cell fates of Bhlhb5-lineage cells were identified by using specific cell markers and were compared between normal and Bhlhb5-null retinas. Results In addition to GABAergic amacrine and OFF-CB cells, Bhlhb5 lineage cells give rise to ganglion, glycinergic amacrine, rod bipolar, ON-bipolar, and rod photoreceptor cells during normal retinal development. Targeted deletion of Bhlhb5 resulted in the loss of GABAergic amacrine, glycinergic amacrine, dopaminergic amacrine, and Type 2 OFF-CB cells. Furthermore, in the absence of BHLHB5, a portion of Bhlhb5 lineage cells switch their fate and differentiate into cholinergic amacrine cells. Conclusions Our data reveal a broad expression pattern of Bhlhb5 throughout retinogenesis and demonstrate the cell-autonomous as well as non-cell-autonomous role of Bhlhb5 in the specification of amacrine and bipolar subtypes. PMID:24123365

Huang, Liang; Hu, Fang; Feng, Liang; Luo, Xiong-Jian; Liang, Guoqing; Zeng, Xiang-Yun; Yi, Jing-Lin; Gan, Lin



Hypoxia-Inducible Aryl Hydrocarbon Receptor Nuclear Translocator (ARNT) (HIF-1?): Is It a Rare Exception?  

PubMed Central

The aryl hydrocarbon receptor nuclear translocator (ARNT), also designated as hypoxia-inducible factor (HIF)-1?, plays a pivotal role in the adaptive responses to (micro-)environmental stresses such as dioxin exposure and oxygen deprivation (hypoxia). ARNT belongs to the group of basic helix-loop-helix (bHLH)–Per-ARNT-Sim (PAS) transcription factors, which act as heterodimers. ARNT serves as a common binding partner for the aryl hydrocarbon receptor (AhR) as well as HIF-? subunits. HIF-? proteins are regulated in an oxygen-dependent manner, whereas ARNT is generally regarded as constitutively expressed, meaning that neither the arnt mRNA nor the protein level is influenced by hypoxia (despite the name HIF-1?). However, there is emerging evidence that tumor cells derived from different entities are able to upregulate ARNT, especially under low oxygen tension in a cell-specific manner. The objective of this review is therefore to highlight and summarize current knowledge regarding the hypoxia-dependent upregulation of ARNT, which is in sharp contrast to the general point of view described in the literature. Elucidating the mechanism behind this rare cellular attribute will help us to gain new insights into HIF biology and might provide new strategies for anti-cancer therapeutics. In conclusion, putative treatment effects on ARNT should be taken into account while studying the HIF pathway. This step is of great importance when ARNT is intended to serve as a loading control or as a reference. PMID:24849811

Mandl, Markus; Depping, Reinhard



Id4 suppresses MMP2-mediated invasion of glioblastoma-derived cells by direct inactivation of Twist1 function.  


Tumor cell invasion is a major contributor to cancer morbidity, and is of particular importance in patients with glioblastoma multiforme (GBM), the highest grade and most aggressive primary brain tumor. Tumor cell invasion and the expression of matrix metalloproteinases (MMPs), which are required for GBM invasion, are enhanced by inhibitor of DNA binding (Id) gene family members, Id1, Id2 and Id3, which can be highly expressed in glioma. Id4 is expressed in GBM at more variable levels than these other family members and we sought to determine its role in invasion. We found, unexpectedly, that invasion was dramatically inhibited in cells expressing Id4 as a result of decreased MMP2, a secreted proteinase key for brain tumor invasion. We demonstrate that Id4 decreased MMP2 expression by a direct inhibitory interaction with Twist1, a basic helix-loop-helix transcription factor known to increase MMP2 expression. Importantly, using data from The Cancer Genome Atlas, we show that Id4 expression correlates with survival of glioblastoma patients and inversely correlates with MMP2 expression. These data suggest that the upregulation of MMP2 resulting from decreased Id4 expression in GBM may contribute to the morbidity and mortality of GBM patients. PMID:24413082

Rahme, G J; Israel, M A



RNA Profiling and Chromatin Immunoprecipitation-Sequencing Reveal that PTF1a Stabilizes Pancreas Progenitor Identity via the Control of MNX1/HLXB9 and a Network of Other Transcription Factors  

PubMed Central

Pancreas development is initiated by the specification and expansion of a small group of endodermal cells. Several transcription factors are crucial for progenitor maintenance and expansion, but their interactions and the downstream targets mediating their activity are poorly understood. Among those factors, PTF1a, a basic helix-loop-helix (bHLH) transcription factor which controls pancreas exocrine cell differentiation, maintenance, and functionality, is also needed for the early specification of pancreas progenitors. We used RNA profiling and chromatin immunoprecipitation (ChIP) sequencing to identify a set of targets in pancreas progenitors. We demonstrate that Mnx1, a gene that is absolutely required in pancreas progenitors, is a major direct target of PTF1a and is regulated by a distant enhancer element. Pdx1, Nkx6.1, and Onecut1 are also direct PTF1a targets whose expression is promoted by PTF1a. These proteins, most of which were previously shown to be necessary for pancreas bud maintenance or formation, form a transcription factor network that allows the maintenance of pancreas progenitors. In addition, we identify Bmp7, Nr5a2, RhoV, and P2rx1 as new targets of PTF1a in pancreas progenitors. PMID:22232429

Thompson, Nancy; Gésina, Emilie; Scheinert, Peter; Bucher, Philipp



Characterization of sequences in human TWIST required for nuclear localization  

PubMed Central

Background Twist is a transcription factor that plays an important role in proliferation and tumorigenesis. Twist is a nuclear protein that regulates a variety of cellular functions controlled by protein-protein interactions and gene transcription events. The focus of this study was to characterize putative nuclear localization signals (NLSs) 37RKRR40 and 73KRGKK77 in the human TWIST (H-TWIST) protein. Results Using site-specific mutagenesis and immunofluorescences, we observed that altered TWISTNLS1 K38R, TWISTNLS2 K73R and K77R constructs inhibit nuclear accumulation of H-TWIST in mammalian cells, while TWISTNLS2 K76R expression was un-affected and retained to the nucleus. Subsequently, co-transfection of TWIST mutants K38R, K73R and K77R with E12 formed heterodimers and restored nuclear localization despite the NLSs mutations. Using a yeast-two-hybrid assay, we identified a novel TWIST-interacting candidate TCF-4, a basic helix-loop-helix transcription factor. The interaction of TWIST with TCF-4 confirmed using NLS rescue assays, where nuclear expression of mutant TWISTNLS1 with co-transfixed TCF-4 was observed. The interaction of TWIST with TCF-4 was also seen using standard immunoprecipitation assays. Conclusion Our study demonstrates the presence of two putative NLS motifs in H-TWIST and suggests that these NLS sequences are functional. Furthermore, we identified and confirmed the interaction of TWIST with a novel protein candidate TCF-4. PMID:19534813

Singh, Shalini; Gramolini, Anthony O



Nuclear translocation of Hand-1 acts as a molecular switch to regulate vascular radiosensitivity in medulloblastoma tumors: the protein uPAR is a cytoplasmic sequestration factor for Hand-1.  


Urokinase-type plasminogen activator receptor (uPAR) is overexpressed in the tumor-stromal invasive microenvironment in many human cancers, including medulloblastoma. The role of uPAR in tumor progression and angiogenesis has been well characterized. Previously, in medulloblastoma cells, we showed that ionizing radiation (IR)-induced uPAR is a potent activator of cancer stem cell (CSC)-like properties and is associated with various transcription factors that are involved during embryonic development and cancer. In the present study, we show that uPAR protein acts as a cytoplasmic sequestration factor for a novel basic helix-loop-helix transcription factor, Hand-1. The Hand-1 protein plays an essential role in the differentiation of trophoblast giant cells and cardiac morphogenesis, and yet its precise cellular function and its contribution to cancer remain mostly unknown. We also observed that the Hand-1 protein is upregulated in uPAR short hairpin RNA-treated medulloblastoma cells and accompanies sustained cell growth and angiogenesis. Furthermore, IR-induced uPAR overexpression negatively regulates Hand-1 activity and results in the stabilization of angiogenesis-promoting molecules, including hypoxia-inducible factor-1?. Finally, uPAR overexpression and its association with Hand-1 after IR treatment indicate that uPAR is capable of regulating Hand-1 and that uPAR has a role in the process of IR-induced tumor angiogenesis. PMID:24623737

Asuthkar, Swapna; Gogineni, Venkateswara Rao; Rao, Jasti S; Velpula, Kiran Kumar



Take a deep breath: peptide signalling in stomatal patterning and differentiation.  


Stomata are pores in the leaf surface that open and close to regulate gas exchange and minimize water loss. In Arabidopsis, a pair of guard cells surrounds each stoma and they are derived from precursors distributed in an organized pattern on the epidermis. Stomatal differentiation follows a well-defined developmental programme, regulated by stomatal lineage-specific basic helix-loop-helix transcription factors, and stomata are consistently separated by at least one epidermal cell (referred to as the 'one-cell-spacing rule') to allow for proper opening and closure of the stomatal aperture. Peptide signalling is involved in regulating stomatal differentiation and in enforcing the one-cell-spacing rule. The cysteine-rich peptides EPIDERMAL PATTERNING FACTOR 1 (EPF1) and EPF2 negatively regulate stomatal differentiation in cells adjacent to stomatal precursors, while STOMAGEN/EPFL9 is expressed in the mesophyll of developing leaves and positively regulates stomatal development. These peptides work co-ordinately with the ERECTA family of leucine-rich repeat (LRR) receptor-like kinases and the LRR receptor-like protein TOO MANY MOUTHS. Recently, specific ligand-receptor pairs were identified that function at two different stages of stomatal development to restrict entry into the stomatal lineage, and later to orient precursor division away from existing stomata. These studies have provided the groundwork to begin to understand the molecular mechanisms involved in cell-cell communication during stomatal development. PMID:23997204

Richardson, Lynn G L; Torii, Keiko U



Sequence and function of bHLHs required for stomatal development in Arabidopsis are deeply conserved in land plants  

PubMed Central

Stomata are a broadly conserved feature of land plants with a crucial role regulating transpiration and gas exchange between the plant and atmosphere. Stereotyped cell divisions within a specialized cell lineage of the epidermis generate stomata and define the pattern of their distribution. The behavior of the stomatal lineage varies in its detail among different plant groups, but general features include asymmetric cell divisions and an immediate precursor (the guard mother cell, GMC) that divides symmetrically to form the pair of cells that will differentiate into the guard cells. In Arabidopsis, the closely related basic helix-loop-helix subgroup Ia transcription factors SPEECHLESS, MUTE and FAMA promote asymmetric divisions, the acquisition of GMC identity and guard cell differentiation, respectively. Genome sequence data indicate that these key positive regulators of stomatal development are broadly conserved among land plants. While orthologies can be established among individual family members within the angiosperms, more distantly related groups contain subgroup Ia bHLHs of unclear affinity. We demonstrate group Ia members from the moss Physcomitrella patens can partially complement MUTE and FAMA and recapitulate gain of function phenotypes of group Ia genes in multiple steps in the stomatal lineage in Arabidopsis. Our data are consistent with a mechanism whereby a multifunctional transcription factor underwent duplication followed by specialization to provide the three (now non-overlapping) functions of the angiosperm stomatal bHLHs. PMID:21410874

MacAlister, Cora A.; Bergmann, Dominique C.



Out of the Mouths of Plants: The Molecular Basis of the Evolution and Diversity of Stomatal Development[W  

PubMed Central

Stomata are microscopic valves on the plant epidermis that played a critical role in the evolution of land plants. Studies in the model dicot Arabidopsis thaliana have identified key transcription factors and signaling pathways controlling stomatal patterning and differentiation. Three paralogous Arabidopsis basic helix-loop-helix proteins, SPEECHLESS (SPCH), MUTE, and FAMA, mediate sequential steps of cell-state transitions together with their heterodimeric partners SCREAM (SCRM) and SCRM2. Cell–cell signaling components, including putative ligands, putative receptors, and mitogen-activated protein kinase cascades, orient asymmetric cell divisions and prevent overproduction and clustering of stomata. The recent availability of genome sequence and reverse genetics tools for model monocots and basal land plants allows for the examination of the conservation of genes important in stomatal patterning and differentiation. Studies in grasses have revealed that divergence of SPCH-MUTE-FAMA predates the evolutionary split of monocots and dicots and that these proteins show conserved and novel roles in stomatal differentiation. By contrast, specific asymmetric cell divisions in Arabidopsis and grasses require unique molecular components. Molecular phylogenetic analysis implies potential conservation of signaling pathways and prototypical functions of the transcription factors specifying stomatal differentiation. PMID:20179138

Peterson, Kylee M.; Rychel, Amanda L.; Torii, Keiko U.



The bHLH142 Transcription Factor Coordinates with TDR1 to Modulate the Expression of EAT1 and Regulate Pollen Development in Rice[C][W][OPEN  

PubMed Central

Male sterility plays an important role in F1 hybrid seed production. We identified a male-sterile rice (Oryza sativa) mutant with impaired pollen development and a single T-DNA insertion in the transcription factor gene bHLH142. Knockout mutants of bHLH142 exhibited retarded meiosis and defects in tapetal programmed cell death. RT-PCR and in situ hybridization analyses showed that bHLH142 is specifically expressed in the anther, in the tapetum, and in meiocytes during early meiosis. Three basic helix-loop-helix transcription factors, UDT1 (bHLH164), TDR1 (bHLH5), and EAT1/DTD1 (bHLH141) are known to function in rice pollen development. bHLH142 acts downstream of UDT1 and GAMYB but upstream of TDR1 and EAT1 in pollen development. In vivo and in vitro assays demonstrated that bHLH142 and TDR1 proteins interact. Transient promoter assays demonstrated that regulation of the EAT1 promoter requires bHLH142 and TDR1. Consistent with these results, 3D protein structure modeling predicted that bHLH142 and TDR1 form a heterodimer to bind to the EAT1 promoter. EAT1 positively regulates the expression of AP37 and AP25, which induce tapetal programmed cell death. Thus, in this study, we identified bHLH142 as having a pivotal role in tapetal programmed cell death and pollen development. PMID:24894043

Ko, Swee-Suak; Li, Min-Jeng; Sun-Ben Ku, Maurice; Ho, Yi-Cheng; Lin, Yi-Jyun; Chuang, Ming-Hsing; Hsing, Hong-Xian; Lien, Yi-Chen; Yang, Hui-Ting; Chang, Hung-Chia; Chan, Ming-Tsair



Tfe3 expression is closely associated to macrophage terminal differentiation of human hematopoietic myeloid precursors  

SciTech Connect

The MItf-Tfe family of basic helix-loop-helix leucine zipper (bHLH-Zip) transcription factors encodes four family members: MItf, Tfe3, TfeB and TfeC. In vitro, each protein of the family binds DNA in a homo- or heterodimeric form with other family members. Tfe3 is involved in chromosomal translocations recurrent in different tumors and it has been demonstrated, by in vivo studies, that it plays, redundantly with MItf, an important role in the process of osteoclast formation, in particular during the transition from mono-nucleated to multi-nucleated osteoclasts. Since mono-nucleated osteoclasts derive from macrophages we investigated whether Tfe3 might play a role upstream during hematopoietic differentiation. Here we show that Tfe3 is able to induce mono-macrophagic differentiation of U937 cells, in association with a decrease of cell proliferation and an increase of apoptosis. We also show that Tfe3 does not act physiologically during commitment of CD34+ hematopoietic stem cells (HSCs), since it is not able to direct HSCs toward a specific lineage as observed by clonogenic assay, but is a strong actor of terminal differentiation since it allows human primary myeloblasts' maturation toward the macrophage lineage.

Zanocco-Marani, Tommaso [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy); Vignudelli, Tatiana [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy); Gemelli, Claudia [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy); Pirondi, Sara [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy); Testa, Anna [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy); Montanari, Monica [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy); Parenti, Sandra [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy); Tenedini, Elena [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy); Grande, Alexis [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy); Ferrari, Sergio [Dipartimento di Scienze Biomediche, Sezione di Chimica Biologica, Universita di Modena e Reggio Emilia, Via Campi 287, 41100, Modena (Italy)]. E-mail:



MYC2 Differentially Modulates Diverse Jasmonate-Dependent Functions in Arabidopsis[W  

PubMed Central

The Arabidopsis thaliana basic helix-loop-helix Leu zipper transcription factor (TF) MYC2/JIN1 differentially regulates jasmonate (JA)-responsive pathogen defense (e.g., PDF1.2) and wound response (e.g., VSP) genes. In this study, genome-wide transcriptional profiling of wild type and mutant myc2/jin1 plants followed by functional analyses has revealed new roles for MYC2 in the modulation of diverse JA functions. We found that MYC2 negatively regulates Trp and Trp-derived secondary metabolism such as indole glucosinolate biosynthesis during JA signaling. Furthermore, MYC2 positively regulates JA-mediated resistance to insect pests, such as Helicoverpa armigera, and tolerance to oxidative stress, possibly via enhanced ascorbate redox cycling and flavonoid biosynthesis. Analyses of MYC2 cis binding elements and expression of MYC2-regulated genes in T-DNA insertion lines of a subset of MYC2–regulated TFs suggested that MYC2 might modulate JA responses via differential regulation of an intermediate spectrum of TFs with activating or repressing roles in JA signaling. MYC2 also negatively regulates its own expression, and this may be one of the mechanisms used in fine-tuning JA signaling. Overall, these results provide new insights into the function of MYC2 and the transcriptional coordination of the JA signaling pathway. PMID:17616737

Dombrecht, Bruno; Xue, Gang Ping; Sprague, Susan J.; Kirkegaard, John A.; Ross, John J.; Reid, James B.; Fitt, Gary P.; Sewelam, Nasser; Schenk, Peer M.; Manners, John M.; Kazan, Kemal



Temporal regulation of Ath5 gene expression during eye development  

PubMed Central

During central nervous system development the timing of progenitor differentiation must be precisely controlled to generate the proper number and complement of neuronal cell types. Proneural basic helix-loop-helix (bHLH) transcription factors play a central role in regulating neurogenesis, and thus the timing of their expression must be regulated to ensure that they act at the appropriate developmental time. In the developing retina, the expression of the bHLH factor Ath5 is controlled by multiple signals in early retinal progenitors, although less is known about how these signals are coordinated to ensure correct spatial and temporal pattern of gene expression. Here we identify a key distal Xath5 enhancer and show that this enhancer regulates the early phase of Xath5 expression, while the proximal enhancer we previously identified acts later. The distal enhancer responds to Pax6, a key patterning factor in the optic vesicle, while FGF signaling regulates Xath5 expression through sequences outside of this region. In addition, we have identified an inhibitory element adjacent to the conserved distal enhancer region that is required to prevent premature initiation of expression in the retina. This temporal regulation of Xath5 gene expression is comparable to proneural gene regulation in Drosophila, whereby separate enhancers regulate different temporal phases of expression. PMID:19059393

Willardsen, Minde I.; Suli, Arminda; Pan, Yi; Marsh-Armstrong, Nicholas; Chien, Chi-Bin; El-Hodiri, Heithem; Brown, Nadean L.; Moore, Kathryn B.; Vetter, Monica L.



Omega-3 Polyunsaturated Fatty Acids Enhance Neuronal Differentiation in Cultured Rat Neural Stem Cells  

PubMed Central

Polyunsaturated fatty acids (PUFAs) can induce neurogenesis and recovery from brain diseases. However, the exact mechanisms of the beneficial effects of PUFAs have not been conclusively described. We recently reported that docosahexaenoic acid (DHA) induced neuronal differentiation by decreasing Hes1 expression and increasing p27kip1 expression, which causes cell cycle arrest in neural stem cells (NSCs). In the present study, we examined the effect of eicosapentaenoic acid (EPA) and arachidonic acid (AA) on differentiation, expression of basic helix-loop-helix transcription factors (Hes1, Hes6, and NeuroD), and the cell cycle of cultured NSCs. EPA also increased mRNA levels of Hes1, an inhibitor of neuronal differentiation, Hes6, an inhibitor of Hes1, NeuroD, and Map2 mRNA and Tuj-1-positive cells (a neuronal marker), indicating that EPA induced neuronal differentiation. EPA increased the mRNA levels of p21cip1 and p27kip1, a cyclin-dependent kinase inhibitor, which indicated that EPA induced cell cycle arrest. Treatment with AA decreased Hes1 mRNA but did not affect NeuroD and Map2 mRNA levels. Furthermore, AA did not affect the number of Tuj-1-positive cells or cell cycle progression. These results indicated that EPA could be involved in neuronal differentiation by mechanisms alternative to those of DHA, whereas AA did not affect neuronal differentiation in NSCs. PMID:23365582

Katakura, Masanori; Hashimoto, Michio; Okui, Toshiyuki; Shahdat, Hossain Md; Matsuzaki, Kentaro; Shido, Osamu



Arabidopsis thaliana ICE2 gene: Phylogeny, structural evolution and functional diversification from ICE1.  


The ability to tolerate environmental stresses is crucial for all living organisms, and gene duplication is one of the sources for evolutionary novelties. Arabidopsis thaliana INDUCER OF CBF EXPRESSION1 and 2 (ICE1 and ICE2) encode MYC-type bHLH (basic helix-loop-helix) transcription factors. They confer cold stress tolerance by induction of the CBF/DREB1 regulon and regulate stomata formation. Although ICE2 is closely related to ICE1, its origin and role in cold response remains uncertain. Here, we used a bioinformatics/phylogenetic approach to uncover the ICE2 evolutionary history, structural evolution and functional divergence from the putative ancestral gene. Sequence diversification from ICE1 included the gain of cis-acting elements in ICE2 promoter sequence that may provide meristem-specific and defense-related gene expression. By analyzing transgenic Arabidopsis lines with ICE2 over-expression we showed that it contributes to stomata formation, flowering time regulation and cold response. Constitutive ICE2 expression led to induced meristem freezing tolerance, resulting from activation of CBF1 and CBF3 genes and ABA biosynthesis by NCED3 induction. We presume that ICE2 gene has originated from a duplication event about 17.9MYA followed by sub- and neofunctionalization of the ancestral ICE1 gene. Moreover, we predict its role in pathogen resistance and flowering time regulation. PMID:25443829

Kurbidaeva, Amina; Ezhova, Tatiana; Novokreshchenova, Maria



CCAR1 is required for Ngn3-mediated endocrine differentiation  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer We identify CCAR1 to directly interact with Ngn3. Black-Right-Pointing-Pointer CCAR1 is co-localized with Ngn3 in the nucleus. Black-Right-Pointing-Pointer CCAR1 cooperates with Ngn3 in activating NeuroD expression. Black-Right-Pointing-Pointer CCAR1 is required for Ngn3-mediated PANC-1 transdifferentiation. -- Abstract: Neurogenin3 (Ngn3) is a basic helix-loop-helix transcription factor that specifies pancreatic endocrine cell fates during pancreas development. It can also initiate a transdifferentiation program when expressed in pancreatic exocrine and ductal cells. However, how Ngn3 initiates a transcriptional cascade to achieve endocrine differentiation is still poorly understood. Here, we show that cell cycle and apoptosis regulator 1 (CCAR1), which is a transcriptional coactivator for nuclear receptors, also interacts with Ngn3. The association between Ngn3 and CCAR1 was verified by pull-down assays and co-immunoprecipitation analyses. Using gene reporter assays, we found that CCAR1 is essential for Ngn3 to activate the expression of the reporter genes containing the NeuroD promoter. Moreover, down-regulation of endogenous CCAR1 in the PANC-1 pancreatic ductal cell line inhibits the transdifferentiation program initiated by Ngn3. CCAR1 is, therefore, a novel partner of Ngn3 in mediating endocrine differentiation.

Lu, Chung-Kuang [Department of Life Science, National Chung Cheng University, Chia-Yi, Taiwan, ROC (China)] [Department of Life Science, National Chung Cheng University, Chia-Yi, Taiwan, ROC (China); Lai, Yi-Chyi [Department of Microbiology and Immunology, Chung Shan Medical University, Taichung, Taiwan, ROC (China)] [Department of Microbiology and Immunology, Chung Shan Medical University, Taichung, Taiwan, ROC (China); Lin, Yung-Fu; Chen, Hau-Ren [Department of Life Science, National Chung Cheng University, Chia-Yi, Taiwan, ROC (China)] [Department of Life Science, National Chung Cheng University, Chia-Yi, Taiwan, ROC (China); Chiang, Ming-Ko, E-mail: [Department of Life Science, National Chung Cheng University, Chia-Yi, Taiwan, ROC (China)] [Department of Life Science, National Chung Cheng University, Chia-Yi, Taiwan, ROC (China)



Evolution of the Max and Mlx Networks in Animals  

PubMed Central

Transcription factors (TFs) are essential for the regulation of gene expression and often form emergent complexes to perform vital roles in cellular processes. In this paper, we focus on the parallel Max and Mlx networks of TFs because of their critical involvement in cell cycle regulation, proliferation, growth, metabolism, and apoptosis. A basic-helix-loop-helix-zipper (bHLHZ) domain mediates the competitive protein dimerization and DNA binding among Max and Mlx network members to form a complex system of cell regulation. To understand the importance of these network interactions, we identified the bHLHZ domain of Max and Mlx network proteins across the animal kingdom and carried out several multivariate statistical analyses. The presence and conservation of Max and Mlx network proteins in animal lineages stemming from the divergence of Metazoa indicate that these networks have ancient and essential functions. Phylogenetic analysis of the bHLHZ domain identified clear relationships among protein families with distinct points of radiation and divergence. Multivariate discriminant analysis further isolated specific amino acid changes within the bHLHZ domain that classify proteins, families, and network configurations. These analyses on Max and Mlx network members provide a model for characterizing the evolution of TFs involved in essential networks. PMID:21859806

McFerrin, Lisa G.; Atchley, William R.



Tcf15 Primes Pluripotent Cells for Differentiation  

PubMed Central

Summary The events that prime pluripotent cells for differentiation are not well understood. Inhibitor of DNA binding/differentiation (Id) proteins, which are inhibitors of basic helix-loop-helix (bHLH) transcription factor activity, contribute to pluripotency by blocking sequential transitions toward differentiation. Using yeast-two-hybrid screens, we have identified Id-regulated transcription factors that are expressed in embryonic stem cells (ESCs). One of these, Tcf15, is also expressed in the embryonic day 4.5 embryo and is specifically associated with a novel subpopulation of primed ESCs. An Id-resistant form of Tcf15 rapidly downregulates Nanog and accelerates somatic lineage commitment. We propose that because Tcf15 can be held in an inactive state through Id activity, it may prime pluripotent cells for entry to somatic lineages upon downregulation of Id. We also find that Tcf15 expression is dependent on fibroblast growth factor (FGF) signaling, providing an explanation for how FGF can prime for differentiation without driving cells out of the pluripotent state. PMID:23395635

Davies, Owen R.; Lin, Chia-Yi; Radzisheuskaya, Aliaksandra; Zhou, Xinzhi; Taube, Jessica; Blin, Guillaume; Waterhouse, Anna; Smith, Andrew J.H.; Lowell, Sally



Development of inner ear afferent connections: forming primary neurons and connecting them to the developing sensory epithelia  

PubMed Central

The molecular and cellular origin of the primary neurons of the inner ear, the vestibular and spiral neurons, is reviewed including how they connect to the specific sensory epithelia and what the molecular nature of their survival is. Primary neurons of the ear depend on a single basic Helix-Loop-Helix (bHLH) protein for their formation, neurogenin 1 (ngn1). An immediate downstream gene is the bHLH gene neuronal differentiation (NeuroD). Targeted null mutations of ngn1 results in absence of primary neuron formation; targeted null mutation of NeuroD results in loss of almost all spiral and many vestibular neurons. NeuroD and a later expressed gene, Brn3a, play a role in pathfinding to and within sensory epithelia. The molecular nature of this pathfinding property is unknown. Reduction of hair cells in ngn1 null mutations suggests a clonal relationship with primary neurons. This relationship may play some role in specifying the identity of hair cells and the primary neurons that connect with them. Primary neuron neurites growth to sensory epithelia is initially independent of trophic factors released from developing sensory epithelia, but becomes rapidly dependent on those factors. Null mutations of specific neurotrophic factors lose distinct primary neuron populations which undergo rapid embryonic cell death. PMID:12787865

Fritzsch, Bernd



Cardiomyopathy in Irx4-Deficient Mice Is Preceded by Abnormal Ventricular Gene Expression  

PubMed Central

To define the role of Irx4, a member of the Iroquois family of homeobox transcription factors in mammalian heart development and function, we disrupted the murine Irx4 gene. Cardiac morphology in Irx4-deficient mice (designated Irx4?ex2/?ex2) was normal during embryogenesis and in early postnatal life. Adult Irx4?ex2/?ex2 mice developed a cardiomyopathy characterized by cardiac hypertrophy and impaired contractile function. Prior to the development of cardiomyopathy, Irx4?ex2/?ex2 hearts had abnormal ventricular gene expression: Irx4-deficient embryos exhibited reduced ventricular expression of the basic helix-loop-helix transcription factor eHand (Hand1), increased Irx2 expression, and ventricular induction of an atrial chamber-specific transgene. In neonatal hearts, ventricular expression of atrial natriuretic factor and ?-skeletal actin was markedly increased. Several weeks subsequent to these changes in embryonic and neonatal gene expression, increased expression of hypertrophic markers BNP and ?-myosin heavy chain accompanied adult-onset cardiac hypertrophy. Cardiac expression of Irx1, Irx2, and Irx5 may partially compensate for loss of Irx4 function. We conclude that Irx4 is not sufficient for ventricular chamber formation but is required for the establishment of some components of a ventricle-specific gene expression program. In the absence of genes under the control of Irx4, ventricular function deteriorates and cardiomyopathy ensues. PMID:11238910

Bruneau, Benoit G.; Bao, Zheng-Zheng; Fatkin, Diane; Xavier-Neto, Jose; Georgakopoulos, Dimitrios; Maguire, Colin T.; Berul, Charles I.; Kass, David A.; Kuroski-de Bold, Mercedes L.; de Bold, Adolfo J.; Conner, David A.; Rosenthal, Nadia; Cepko, Constance L.; Seidman, Christine E.; Seidman, J. G.



Twist Factor Regulation of Non-cardiomyocyte Cell Lineages in the Developing Heart  

PubMed Central

The heart is a complex organ that is composed of numerous cell types, which must integrate their programs for proper specification, differentiation and cardiac morphogenesis. During cardiogenesis members of the Twist-family of basic helix-loop-helix (bHLH) transcription factors play distinct roles within cardiac lineages such as the endocardium and extra-cardiac lineages such as the cardiac neural crest (cNCC) and epicardium. While the study of these cell populations is often eclipsed by that of cardiomyocytes, the contributions of non-cardiomyocytes to development and disease are increasingly being appreciated as both dynamic and essential. This review summarizes what is known regarding Twist-family bHLH function in extra-cardiac cell populations and the endocardium, with a focus on regulatory mechanisms, downstream targets, and expression profiles. Improving our understanding of the molecular pathways that Twist-family bHLH factors mediate in these lineages will be necessary to ascertain how their dysfunction leads to congenital disease and adult pathologies such as myocardial infarctions and cardiac fibroblast induced fibrosis. Indeed, this knowledge will prove to be critical to clinicians seeking to improve current treatments. PMID:22516205

VanDusen, Nathan J.; Firulli, Anthony B.



RICE SALT SENSITIVE3 Forms a Ternary Complex with JAZ and Class-C bHLH Factors and Regulates Jasmonate-Induced Gene Expression and Root Cell Elongation[C][W  

PubMed Central

Plasticity of root growth in response to environmental cues and stresses is a fundamental characteristic of land plants. However, the molecular basis underlying the regulation of root growth under stressful conditions is poorly understood. Here, we report that a rice nuclear factor, RICE SALT SENSITIVE3 (RSS3), regulates root cell elongation during adaptation to salinity. Loss of function of RSS3 only moderately inhibits cell elongation under normal conditions, but it provokes spontaneous root cell swelling, accompanied by severe root growth inhibition, under saline conditions. RSS3 is preferentially expressed in the root tip and forms a ternary complex with class-C basic helix-loop-helix (bHLH) transcription factors and JASMONATE ZIM-DOMAIN proteins, the latter of which are the key regulators of jasmonate (JA) signaling. The mutated protein arising from the rss3 allele fails to interact with bHLH factors, and the expression of a significant portion of JA-responsive genes is upregulated in rss3. These results, together with the known roles of JAs in root growth regulation, suggest that RSS3 modulates the expression of JA-responsive genes and plays a crucial role in a mechanism that sustains root cell elongation at appropriate rates under stressful conditions. PMID:23715469

Toda, Yosuke; Tanaka, Maiko; Ogawa, Daisuke; Kurata, Kyo; Kurotani, Ken-ichi; Habu, Yoshiki; Ando, Tsuyu; Sugimoto, Kazuhiko; Mitsuda, Nobutaka; Katoh, Etsuko; Abe, Kiyomi; Miyao, Akio; Hirochika, Hirohiko; Hattori, Tsukaho; Takeda, Shin



FCA mediates thermal adaptation of stem growth by attenuating auxin action in Arabidopsis.  


Global warming is predicted to profoundly affect plant distribution and crop yield in the near future. Higher ambient temperature can influence diverse aspects of plant growth and development. In Arabidopsis, the basic helix-loop-helix transcription factor PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) regulates temperature-induced adaptive responses by modulating auxin biosynthesis. At high temperature, PIF4 directly activates expression of YUCCA8 (YUC8), a gene encoding an auxin biosynthetic enzyme, resulting in auxin accumulation. Here we demonstrate that the RNA-binding protein FCA attenuates PIF4 activity by inducing its dissociation from the YUC8 promoter at high temperature. At 28?°C, auxin content is elevated in FCA-deficient mutants that exhibit elongated stems but reduced in FCA-overexpressing plants that exhibit reduced stem growth. We propose that the FCA-mediated regulation of YUC8 expression tunes down PIF4-induced architectural changes to achieve thermal adaptation of stem growth at high ambient temperature. PMID:25400039

Lee, Hyo-Jun; Jung, Jae-Hoon; Cortés Llorca, Lucas; Kim, Sang-Gyu; Lee, Sangmin; Baldwin, Ian T; Park, Chung-Mo



Metastasis-associated protein 1 (MTA1) is an essential downstream effector of the c-MYC oncoprotein  

PubMed Central

The c-myc oncogene is among the most commonly overexpressed genes in human cancer. c-myc encodes a basic helix–loop–helix/leucine zipper (bHLH/LZ) transcription factor (c-MYC) that activates a cascade of downstream targets that ultimately mediate cellular transformation. Although a large number of genes are regulated by c-MYC, only a few have been functionally linked to c-MYC-mediated transformation. By expression profiling, the metastasis-associated protein 1 (MTA1) gene was identified here as a target of the c-MYC oncoprotein in primary human cells, a result confirmed in human cancer cells. MTA1 itself has been previously implicated in cellular transformation, in part through its ability to regulate the epithelial-to-mesenchymal transition and metastasis. MTA1 is a component of the Mi-2/nucleosome remodeling and deacetylating (NURD) complex that contains both histone deacetylase and nucleosome remodeling activity. The data reported here demonstrate that endogenous c-MYC binds to the genomic MTA1 locus and recruits transcriptional coactivators. Most importantly, short hairpin RNA (shRNA)-mediated knockdown of MTA1 blocks the ability of c-MYC to transform mammalian cells. These data implicate MTA1 and the Mi-2/NURD complex as one of the first downstream targets of c-MYC function that are essential for the transformation potential of c-MYC. PMID:16172399

Zhang, Xiao-yong; DeSalle, Lauren M.; Patel, Jagruti H.; Capobianco, Anthony J.; Yu, Duonan; Thomas-Tikhonenko, Andrei; McMahon, Steven B.



The Role of GH/IGF-I Axis in Muscle Homeostasis During Weightlessness  

NASA Technical Reports Server (NTRS)

Exposure to reduced gravity during space travel profoundly alters the loads placed on bone and muscle. Astronauts suffer significant losses of muscle and bone strength during weightlessness. Exercise as a countermeasure is only partially effective in remedying severe muscle atrophy and bone demineralization. Similar wasting of muscles and bones affects people on Earth during prolonged bed rest or immobilization due to injury. In the absence of weight bearing activity, atrophy occurs primarily in the muscles that act in low power, routine movements and in maintaining posture. Hormonal disfunction could contribute in part to the loss of muscle and bone during spaceflight. Reduced levels of human Growth Hormone (hGH) were found in astronauts during space flight, as well as reduced GH secretory activity was observed from the anterior pituitary in 7-day space flight rats. Growth hormone has been shown to be required for maintenance of muscle mass and bone mineralization, in part by mediating the biosynthesis IGF-I, a small polypeptide growth factor. IGF biosynthesis and secretion plays an important role in potentiating muscle cell differentiation and has been shown to drive the expression of myogenin, a myogenic specific basic helix-loop-helix factor. IGF-I has also been shown to have an important role in potentiating muscle regeneration, repair and adult muscle hypertrophy.

Schwartz, Robert J.



Complex domain interactions regulate stability and activity of closely related proneural transcription factors  

PubMed Central

Characterising post-translational regulation of key transcriptional activators is crucial for understanding how cell division and differentiation are coordinated in developing organisms and cycling cells. One important mode of protein post-translational control is by regulation of half-life via ubiquitin-mediated proteolysis. Two key basic Helix-Loop-Helix transcription factors, Neurogenin 2 (Ngn2) and NeuroD, play central roles in development of the central nervous system but despite their homology, Ngn2 is a highly unstable protein whilst NeuroD is, by comparison, very stable. The basis for and the consequences of the difference in stability of these two structurally and functionally related proteins has not been explored. Here we see that ubiquitylation alone does not determine Ngn2 or NeuroD stability. By making chimeric proteins, we see that the N-terminus of NeuroD in particular has a stabilising effect, whilst despite their high levels of homology, the most conserved bHLH domains of these proneural proteins alone can confer significant changes in protein stability. Despite widely differing stabilities of Ngn2, NeuroD and the chimeric proteins composed of domains of both, there is little correlation between protein half-life and ability to drive neuronal differentiation. Therefore, we conclude that despite significant homology between Ngn2 and NeuroD, the regulation of their stability differs markedly and moreover, stability/instability of the proteins is not a direct correlate of their activity. PMID:24998442

McDowell, Gary S.; Hardwick, Laura J.A.; Philpott, Anna



Screening of transcription factors with transcriptional initiation activity.  


A majority of mammalian promoters are associated with CpG islands. CpG island promoters frequently lack common core promoter elements, such as the TATA box, and often have dispersed transcription start sites. The mechanism through which CpG island promoters are transcriptionally initiated remains unclear. We speculate that some transcription factors can direct transcription initiation by themselves. To test this hypothesis, we screened a variety of transcription factors to see whether they could initiate transcription. Most transcription factors, including specificity protein 1 (Sp1) and nuclear factor Y (NF-Y), showed little transcriptional initiation activity. However, nuclear respiratory factor 1 (NRF-1), the basic helix-loop-helix/leucine zipper (bHLH/ZIP) family of proteins and the E-twenty six (Ets) family of proteins had strong transcriptional activity. We further demonstrated that these transcription factors initiate dispersed transcription. Our studies provide perspectives to the mechanism of transcription initiation from CpG island promoters. PMID:23933270

Zhang, Lang; Yu, Haoyue; Wang, Pan; Ding, Qingyang; Wang, Zhao



Segregating neural and mechanosensory fates in the developing ear: patterning, signaling, and transcriptional control.  


The vertebrate inner ear is composed of multiple sensory receptor epithelia, each of which is specialized for detection of sound, gravity, or angular acceleration. Each receptor epithelium contains mechanosensitive hair cells, which are connected to the brainstem by bipolar sensory neurons. Hair cells and their associated neurons are derived from the embryonic rudiment of the inner ear epithelium, but the precise spatial and temporal patterns of their generation, as well as the signals that coordinate these events, have only recently begun to be understood. Gene expression, lineage tracing, and mutant analyses suggest that both neurons and hair cells are generated from a common domain of neural and sensory competence in the embryonic inner ear rudiment. Members of the Shh, Wnt, and FGF families, together with retinoic acid signals, regulate transcription factor genes within the inner ear rudiment to establish the axial identity of the ear and regionalize neurogenic activity. Close-range signaling, such as that of the Notch pathway, specifies the fate of sensory regions and individual cell types. We also describe positive and negative interactions between basic helix-loop-helix and SoxB family transcription factors that specify either neuronal or sensory fates in a context-dependent manner. Finally, we review recent work on inner ear development in zebrafish, which demonstrates that the relative timing of neurogenesis and sensory epithelial formation is not phylogenetically constrained. PMID:24902666

Raft, Steven; Groves, Andrew K



NeuroD1/beta2 contributes to cell-specific transcription of the proopiomelanocortin gene.  

PubMed Central

NeuroD1/beta2 is a basic helix-loop-helix (bHLH) factor expressed in the endocrine cells of the pancreas and in a subset of neurons as they undergo terminal differentiation. We now show that NeuroD1 is expressed in corticotroph cells of the pituitary gland and that it is involved in cell-specific transcription of the proopiomelanocortin (POMC) gene. It was previously shown that corticotroph-specific POMC transcription depends in part on the action of cell-restricted bHLH factors that were characterized as the CUTE (corticotroph upstream transcription element) (M. Therrien and J. Drouin, Mol. Cell. Biol. 13:2342-2353, 1993) complexes. We now demonstrate that these complexes contain NeuroD1 in association with various ubiquitous bHLH dimerization partners. The NeuroD1-containing heterodimers specifically recognize and activate transcription from the POMC promoter E box that confers transcriptional specificity. Interestingly, the NeuroD1 heterodimers activate transcription in synergy with Ptx1, a Bicoid-related homeodomain protein, which also contributes to corticotroph specificity of POMC transcription. In the adult pituitary gland, NeuroD1 transcripts are detected in POMC-expressing corticotroph cells. Taken together with the restricted pattern of Ptx1 expression, these results suggest that these two factors establish the basis of a combinatorial code for the program of corticotroph-specific gene expression. PMID:9343431

Poulin, G; Turgeon, B; Drouin, J



Genome-Wide Analysis of Genes Targeted by PHYTOCHROME INTERACTING FACTOR 3-LIKE5 during Seed Germination in Arabidopsis[W  

PubMed Central

PHYTOCHROME INTERACTING FACTOR 3-LIKE5 (PIL5) is a basic helix-loop-helix transcription factor that inhibits seed germination by regulating the expression of gibberellin (GA)- and abscisic acid (ABA)-related genes either directly or indirectly. It is not yet known, however, whether PIL5 regulates seed germination solely through GA and ABA. Here, we used Chromatin immunoprecipitation-chip (ChIP-chip) analysis to identify 748 novel PIL5 binding sites in the Arabidopsis thaliana genome. Consistent with the molecular function of PIL5 as a transcription regulator, most of the identified binding sites are located in gene promoter regions. Binding site analysis shows that PIL5 binds to its target sites mainly through the G-box motif in vivo. Microarray analysis reveals that phytochromes regulate a large number of genes mainly through PIL5 during seed germination. Comparison between the ChIP-chip and microarray data indicates that PIL5 regulates 166 genes by directly binding to their promoters. Many of the identified genes encode transcription regulators involved in hormone signaling, while some encode enzymes involved in cell wall modification. Interestingly, PIL5 directly regulates many transcription regulators of hormone signaling and indirectly regulates many genes involved in hormone metabolism. Taken together, our data indicate that PIL5 inhibits seed germination not just through GA and ABA, but also by coordinating hormone signals and modulating cell wall properties in imbibed seeds. PMID:19244139

Oh, Eunkyoo; Kang, Hyojin; Yamaguchi, Shinjiro; Park, Jeongmoo; Lee, Doheon; Kamiya, Yuji; Choi, Giltsu



Myogenin induces higher oxidative capacity in pre-existing mouse muscle fibres after somatic DNA transfer  

PubMed Central

Muscle is a permanent tissue, and in the adult pronounced changes can occur in pre-existing fibres without the formation of new fibres. Thus, the mechanisms responsible for phenotype transformation in the adult might be distinct from mechanisms regulating muscle differentiation during muscle formation and growth. Myogenin is a muscle-specific, basic helix-loop-helix transcription factor that is important during early muscle differentiation. It is also expressed in the adult, where its role is unknown. In this study we have overexpressed myogenin in glycolytic fibres of normal adult mice by electroporation and single-cell intracellular injection of expression vectors. Myogenin had no effects on myosin heavy chain fibre type, but induced a considerable increase in succinate dehydrogenase and NADH dehydrogenase activity, with some type IIb fibres reaching the levels observed histochemically in normal type IIx and IIa fibres. mRNA levels for malate dehydrogenase were similarly altered. The size of the fibres overexpressing myogenin was reduced by 30–50 %. Thus, the transfected fibres acquired a phenotype reminiscent of the phenotype obtained by endurance training in man and other animals, with a higher oxidative capacity and smaller size. We conclude that myogenin can alter pre-existing glycolytic fibres in the intact adult animal. PMID:12598590

Ekmark, Merete; Grønevik, Eirik; Schjerling, Peter; Gundersen, Kristian



Fruit Growth in Arabidopsis Occurs via DELLA-Dependent and DELLA-Independent Gibberellin Responses[W][OA  

PubMed Central

Fruit growth and development depend on highly coordinated hormonal activities. The phytohormone gibberellin (GA) promotes growth by inducing degradation of the growth-repressing DELLA proteins; however, the extent to which DELLA proteins contribute to GA-mediated gynoecium and fruit development remains to be clarified. Here, we provide an in-depth characterization of the role of DELLA proteins in Arabidopsis thaliana fruit growth. We show that DELLA proteins are key regulators of reproductive organ size and important for ensuring optimal fertilization. We demonstrate that the seedless fruit growth (parthenocarpy) observed in della mutants can be directly attributed to the constitutive activation of GA signaling. It has been known for >75 years that another hormone, auxin, can induce formation of seedless fruits. Using mutants with complete lack of DELLA activity, we show here that auxin-induced parthenocarpy occurs entirely through GA signaling in Arabidopsis. Finally, we uncover the existence of a DELLA-independent GA response that promotes fruit growth. This response requires GIBBERELLIN-INSENSITIVE DWARF1–mediated GA perception and a functional 26S proteasome and involves the basic helix-loop-helix protein SPATULA as a key component. Taken together, our results describe additional complexities in GA signaling during fruit development, which may be particularly important to optimize the conditions for successful reproduction. PMID:23064323

Fuentes, Sara; Ljung, Karin; Sorefan, Karim; Alvey, Elizabeth; Harberd, Nicholas P.; Østergaard, Lars



Twist-1 Up-Regulation in Carcinoma Correlates to Poor Survival  

PubMed Central

Epithelial-to-mesenchymal transition (EMT) facilitates tumor metastasis. Twist is a basic helix-loop-helix protein that modulates many target genes through E-box-responsive elements. There are two twist-like proteins, Twist-1 and Twist-2, sharing high structural homology in mammals. Twist-1 was found to be a key factor in the promotion of metastasis of cancer cells, and is known to induce EMT. Twist-1 participation in carcinoma progression and metastasis has been reported in a variety of tumors. However, controversy exists concerning the correlation between Twist-1 and prognostic value with respect to carcinoma. A systematic review and meta-analysis were performed to determine whether the expression of Twist-1 was associated with the prognosis of carcinoma patients. This analysis included 17 studies: four studies evaluated lung cancer, three evaluated head and neck cancer, two evaluated breast cancer, two evaluated esophageal cancer, two evaluated liver cancer and one each evaluated osteosarcoma, bladder, cervical and ovarian cancer. A total of 2006 patients were enrolled in these studies, and the median trial sample size was 118 patients. Twist-1 expression was associated with worse overall survival (OS) at both 3 years (hazard ratio “HR” for death = 2.13, 95% CI = 1.86 to 2.45, p < 0.001) and 5 years (HR for death = 2.01, 95% CI = 1.76 to 2.29, p < 0.001). Expression of Twist-1 is associated with worse survival in carcinoma. PMID:25429425

Wushou, Alimujiang; Hou, Jing; Zhao, Ya-Jun; Shao, Zhi-Ming



Enforced expression of E47 has differential effects on Lmo2-induced T-cell leukemias.  


LIM domain only-2 (LMO2) overexpression in T cells induces leukemia but the molecular mechanism remains to be elucidated. In hematopoietic stem and progenitor cells, Lmo2 is part of a protein complex comprised of class II basic helix loop helix proteins, Tal1and Lyl1. The latter transcription factors heterodimerize with E2A proteins like E47 and Heb to bind E boxes. LMO2 and TAL1 or LYL1 cooperate to induce T-ALL in mouse models, and are concordantly expressed in human T-ALL. Furthermore, LMO2 cooperates with the loss of E2A suggesting that LMO2 functions by creating a deficiency of E2A. In this study, we tested this hypothesis in Lmo2-induced T-ALL cell lines. We transduced these lines with an E47/estrogen receptor fusion construct that could be forced to homodimerize with 4-hydroxytamoxifen. We discovered that forced homodimerization induced growth arrest in 2 of the 4 lines tested. The lines sensitive to E47 homodimerization accumulated in G1 and had reduced S phase entry. We analyzed the transcriptome of a resistant and a sensitive line to discern the E47 targets responsible for the cellular effects. Our results suggest that E47 has diverse effects in T-ALL but that functional deficiency of E47 is not a universal feature of Lmo2-induced T-ALL. PMID:25499232

Goodings, Charnise; Tripathi, Rati; Cleveland, Susan M; Elliott, Natalina; Guo, Yan; Shyr, Yu; Davé, Utpal P



RNA-Seq Data Mining: Downregulation of NeuroD6 Serves as a Possible Biomarker for Alzheimer's Disease Brains  

PubMed Central

Alzheimer's disease (AD) is the most common cause of dementia worldwide with no curative therapies currently available. Previously, global transcriptome analysis of AD brains by microarray failed to identify the set of consistently deregulated genes for biomarker development of AD. Therefore, the molecular pathogenesis of AD remains largely unknown. Whole RNA sequencing (RNA-Seq) is an innovative technology for the comprehensive transcriptome profiling on a genome-wide scale that overcomes several drawbacks of the microarray-based approach. To identify biomarker genes for AD, we analyzed a RNA-Seq dataset composed of the comprehensive transcriptome of autopsized AD brains derived from two independent cohorts. We identified the core set of 522 genes deregulated in AD brains shared between both, compared with normal control subjects. They included downregulation of neuronal differentiation 6 (NeuroD6), a basic helix-loop-helix (bHLH) transcription factor involved in neuronal development, differentiation, and survival in AD brains of both cohorts. We verified the results of RNA-Seq by analyzing three microarray datasets of AD brains different in brain regions, ethnicities, and microarray platforms. Thus, both RNA-Seq and microarray data analysis indicated consistent downregulation of NeuroD6 in AD brains. These results suggested that downregulation of NeuroD6 serves as a possible biomarker for AD brains. PMID:25548427

Yamamoto, Yoji; Asahina, Naohiro; Kitano, Shouta; Kino, Yoshihiro



PHYTOCHROME INTERACTING FACTOR1 Enhances the E3 Ligase Activity of CONSTITUTIVE PHOTOMORPHOGENIC1 to Synergistically Repress Photomorphogenesis in Arabidopsis.  


CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) is a RING/WD40 repeat-containing ubiquitin E3 ligase that is conserved from plants to humans. COP1 forms complexes with SUPPRESSOR OF PHYTOCHROME A (SPA) proteins, and these complexes degrade positively acting transcription factors in the dark to repress photomorphogenesis. Phytochrome-interacting basic helix-loop-helix transcription factors (PIFs) also repress photomorphogenesis in the dark. In response to light, the phytochrome family of sensory photoreceptors simultaneously inactivates COP1-SPA complexes and induces the rapid degradation of PIFs to promote photomorphogenesis. However, the functional relationship between PIFs and COP1-SPA complexes is still unknown. Here, we present genetic evidence that the pif and cop1/spa Arabidopsis thaliana mutants synergistically promote photomorphogenesis in the dark. LONG HYPOCOTYL5 (HY5) is stabilized in the cop1 pif1, spa123 pif1, and pif double, triple, and quadruple mutants in the dark. Moreover, the hy5 mutant suppresses the constitutive photomorphogenic phenotypes of the pifq mutant in the dark. PIF1 forms complexes with COP1, HY5, and SPA1 and enhances the substrate recruitment and autoubiquitylation and transubiquitylation activities of COP1. These data uncover a novel function of PIFs as the potential cofactors of COP1 and provide a genetic and biochemical model of how PIFs and COP1-SPA complexes synergistically repress photomorphogenesis in the dark. PMID:24858936

Xu, Xiaosa; Paik, Inyup; Zhu, Ling; Bu, Qingyun; Huang, Xi; Deng, Xing Wang; Huq, Enamul



Functional Replacement of the Mouse E2A Gene with a Human HEB cDNA  

PubMed Central

The mammalian E2A, HEB, and E2-2 genes encode a unique class of basic helix-loop-helix (bHLH) transcription factors that are evolutionarily conserved and essential for embryonic and postnatal development. While the structural and functional similarities among the gene products are well demonstrated, it is not clear why deletion of E2A, but not HEB or E2-2, leads to a complete arrest in B-lymphocyte development. To understand the molecular basis of the functional specificity between E2A and HEB/E2-2 in mammalian development, we generated and tested a panel of E2A knockin mutations including subtle mutations in the E12 and E47 exons and substitution of both E12 and E47 exons with a human HEB cDNA. We find that the alternatively spliced E12 and E47 bHLH proteins of the E2A gene play similar and additive roles in supporting B lymphopoiesis. Further, we find that HEB driven by the endogenous E2A promoter can functionally replace E2A in supporting B-cell commitment and differentiation toward completion. Finally, the postnatal lethality associated with E2A disruption is fully rescued by the addition of HEB. This study suggests that the functional divergence among E12, E47, and HEB in different cell types is partially defined by the context of gene expression. PMID:9584174

Zhuang, Yuan; Barndt, Robert J.; Pan, Lihua; Kelley, Robert; Dai, Meifang



Virulence Factors of Geminivirus Interact with MYC2 to Subvert Plant Resistance and Promote Vector Performance.  


A pathogen may cause infected plants to promote the performance of its transmitting vector, which accelerates the spread of the pathogen. This positive effect of a pathogen on its vector via their shared host plant is termed indirect mutualism. For example, terpene biosynthesis is suppressed in begomovirus-infected plants, leading to reduced plant resistance and enhanced performance of the whiteflies (Bemisia tabaci) that transmit these viruses. Although begomovirus-whitefly mutualism has been known, the underlying mechanism is still elusive. Here, we identified ?C1 of Tomato yellow leaf curl China virus, a monopartite begomovirus, as the viral genetic factor that suppresses plant terpene biosynthesis. ?C1 directly interacts with the basic helix-loop-helix transcription factor MYC2 to compromise the activation of MYC2-regulated terpene synthase genes, thereby reducing whitefly resistance. MYC2 associates with the bipartite begomoviral protein BV1, suggesting that MYC2 is an evolutionarily conserved target of begomoviruses for the suppression of terpene-based resistance and the promotion of vector performance. Our findings describe how this viral pathogen regulates host plant metabolism to establish mutualism with its insect vector. PMID:25490915

Li, Ran; Weldegergis, Berhane T; Li, Jie; Jung, Choonkyun; Qu, Jing; Sun, Yanwei; Qian, Hongmei; Tee, ChuanSia; van Loon, Joop J A; Dicke, Marcel; Chua, Nam-Hai; Liu, Shu-Sheng; Ye, Jian



TWIST is Expressed in Human Gliomas and Promotes Invasion1  

PubMed Central

Abstract TWIST is a basic helix-loop-helix (bHLH) transcription factor that regulates mesodermal development, promotes tumor cell metastasis, and, in response to cytotoxic stress, enhances cell survival. Our screen for bHLH gene expression in rat C6 glioma revealed TWIST. To delineate a possible oncogenic role for TWIST in the human central nervous system (CNS), we analyzed TWIST message and protein expression in gliomas and normal brain. TWIST was detected in the large majority of human glioma-derived cell lines and human gliomas examined. Increased TWIST mRNA levels were associated with the highest grade gliomas, and increased TWIST expression accompanied transition from low grade to high grade in vivo, suggesting a role for TWIST in promoting malignant progression. In accord, elevated TWIST mRNA abundance preceded the spontaneous malignant transformation of cultured mouse astrocytes hemizygous for p53. Overexpression of TWIST protein in a human glioma cell line significantly enhanced tumor cell invasion, a hallmark of high-grade gliomas. These findings support roles for TWIST both in early glial tumorigenesis and subsequent malignant progression. TWIST was also expressed in embryonic and fetal human brain, and in neurons, but not glia, of mature brain, indicating that, in gliomas, TWIST may promote the functions also critical for CNS development or normal neuronal physiology. PMID:16229805

Elias, Maria C; Tozer, Kathleen R; Silber, John R; Mikheeva, Svetlana; Deng, Mei; Morrison, Richard S; Manning, Thomas C; Silbergeld, Daniel L; Glackin, Carlotta A; Reh, Thomas A; Rostomily, Robert C



The aryl hydrocarbon receptor nuclear translocator (ARNT) family of proteins: transcriptional modifiers with multi-functional protein interfaces.  


The basic Helix-Loop-Helix/PER-ARNT-SIM (bHLH-PAS) domain family of transcription factors mediates cellular responses to a variety of internal and external stimuli. As functional transcription factors, these proteins act as bHLH-PAS heterodimers and can be further sub-classified into sensory/activated subunits and regulatory or ARNT-like proteins. This class of proteins act as master regulators of the bHLH-PAS superfamily of transcription factors that mediate circadian rhythm gene programs, innate and adaptive immune responses, oxygen-sensing mechanisms and compensate for deleterious environmental exposures. Some contribute to the etiology of human pathologies including cancer because of their effects on cell growth and metabolism. We will review the canonical roles of ARNT and ARNT-like proteins with an emphasis on coactivator selectivity and recruitment. We will also discuss recent advances in our understanding of noncanonical DNA-binding independent or off-target roles of ARNT that are uncoupled from its classic heterodimeric bHLH-PAS binding partners. Understanding the DNA binding-independent functions of ARNT may identify novel therapeutic options for the treatment of a large spectrum of disease states. PMID:23116263

Labrecque, M P; Prefontaine, G G; Beischlag, T V



Neuronatin, a Downstream Target of BETA2/NeuroD1 in the Pancreas, Is Involved in Glucose-Mediated Insulin Secretion  

PubMed Central

BETA2 (NeuroD1) is a member of the basic helix-loop-helix transcription factor family. BETA2 plays an important role in the development of the pancreas and the nervous system. Using microarray technology, we identified neuronatin (Nnat) as differentially expressed between wild-type (WT) and knockout (KO) pancreatic RNA from embryonic day 14 (e14.5). NNAT is a member of the proteolipid family of amphipathic polypeptides and is believed to be involved in ion channel transport or channel modulation. Northern blot and in situ hybridization analysis of WT and KO samples confirmed the downregulation of Nnat in pancreas of mutant BETA2 embryos. Chromatin immunoprecipitation and gel shift assays were performed and demonstrated the presence of BETA2 on the Nnat promoter, thus confirming the direct transcriptional regulation of Nnat by BETA2. To assess NNAT potential function, we performed knockdown studies by siRNA in NIT cells and observed a reduction in the ability of the NIT cells to respond to glucose. These results suggest for the first time an important role for NNAT in insulin secretion and for proper ?-cell function. PMID:15793245

Chu, Khoi; Tsai, Ming-Jer



Multisite Light-Induced Phosphorylation of the Transcription Factor PIF3 Is Necessary for Both Its Rapid Degradation and Concomitant Negative Feedback Modulation of Photoreceptor phyB Levels in Arabidopsis[C][W  

PubMed Central

Plants constantly monitor informational light signals using sensory photoreceptors, which include the phytochrome (phy) family (phyA to phyE), and adjust their growth and development accordingly. Following light-induced nuclear translocation, photoactivated phy molecules bind to and induce rapid phosphorylation and degradation of phy-interacting basic Helix Loop Helix (bHLH) transcription factors (PIFs), such as PIF3, thereby regulating the expression of target genes. However, the mechanisms underlying the signal-relay process are still not fully understood. Here, using mass spectrometry, we identify multiple, in vivo, light-induced Ser/Thr phosphorylation sites in PIF3. Using transgenic expression of site-directed mutants of PIF3, we provide evidence that a set of these phosphorylation events acts collectively to trigger rapid degradation of the PIF3 protein in response to initial exposure of dark-grown seedlings to light. In addition, we show that phyB-induced PIF3 phosphorylation is also required for the known negative feedback modulation of phyB levels in prolonged light, potentially through codegradation of phyB and PIF3. This mutually regulatory intermolecular transaction thus provides a mechanism with the dual capacity to promote early, graded, or threshold regulation of the primary, PIF3-controlled transcriptional network in response to initial light exposure, and later, to attenuate global sensitivity to the light signal through reductions in photoreceptor levels upon prolonged exposure. PMID:23903316

Ni, Weimin; Xu, Shou-Ling; Chalkley, Robert J.; Pham, Thao Nguyen D.; Guan, Shenheng; Maltby, Dave A.; Burlingame, Alma L.; Wang, Zhi-Yong; Quail, Peter H.



Expression of the Gs protein alpha-subunit disrupts the normal program of differentiation in cultured murine myogenic cells.  

PubMed Central

The manner in which growth factors acting at the cell surface regulate activity of myogenic basic-helix-loop-helix proteins in the nucleus and thus control the fate of committed skeletal myoblasts remains poorly understood. In this study, we report that immunoreactive Gs protein alpha-subunits (Gs alpha) localize to nuclei of proliferating C2C12 myoblasts but not to nuclei of differentiated postmitotic C2C12 myotubes. To explore the biological significance of this observation, we placed a cDNA encoding Gs alpha in an expression vector under the control of a steroid-inducible promoter and isolated colonies of stably transfected C2C12 myoblasts. Dexamethasone-induced expression of activated Gs alpha markedly delayed differentiation in comparison with uninduced stably transfected cells, which differentiated normally in mitogen-depleted media. Northern blot analysis showed that impaired differentiation was associated with delayed up-regulation of MyoD and myogenin and delayed down-regulation of Id, a dominant negative inhibitor of differentiation. Similar impairment of differentiation could not be reproduced in wild-type C2C12 cells by increasing intracellular cAMP either with forskolin or treatment with a cell-permeable cAMP analog. However, treatment of myoblasts with cholera toxin markedly inhibited myogenic differentiation. Taken together, these findings suggest a novel role for Gs alpha in modulating myogenic differentiation. PMID:9011578

Tsai, C C; Saffitz, J E; Billadello, J J



Developmentally regulated synthesis of p8, a stress-associated transcription cofactor, in diapause-destined embryos of Artemia franciscana  

PubMed Central

?Diapause-destined embryos of the crustacean Artemia franciscana arrest as gastrulae, acquire extreme stress tolerance, and enter profound metabolic dormancy. Among genes upregulated at 2 days postfertilization in these embryos is a homologue of p8, a stress-inducible transcription cofactor. Artemia p8 is smaller than vertebrate homologues but shares a basic helix-loop-helix domain and a bipartite nuclear localization signal. Probing of restriction digested DNA on Southern blots indicated a single Artemia p8 gene and 5?-RACE specified 2 transcription start sites. Several putative cis-acting regulatory sequences, including two heat shock elements, appeared upstream of the p8 transcription start site. Artemia p8 mRNA increased sharply at 1 day postfertilization in diapause-destined embryos and then declined, whereas p8 protein appeared 2 days postfertilization and remained relatively constant throughout development, indicating a stable protein. p8 was not detectable in nauplius-destined (nondiapause) Artemia embryos. Immunofluorescent staining revealed p8 within Artemia nuclei. The results support the idea that p8, a known stress-responsive transcription cofactor, mediates gene expression in diapause-destined Artemia embryos. p8 is the first diapause-related transcription factor identified in crustaceans and 1 of only a small number of such proteins identified in any organism undergoing diapause. PMID:17915558

Qiu, Zhijun; MacRae, Thomas H.



The mammalian single-minded (SIM) gene: Mouse cDNA structure and diencephalic expression indicate a candidate gene for Down syndrome  

SciTech Connect

We have recently isolated a human homolog (hSIM) of the Drosophila single-minded (sim) gene from the Down syndrome critical region of chromosome 21 using the exon trapping method. The Drosophila sim gene encodes a transcription factor that regulates the development of the central nervous system midline cell lineage. To elucidate the structure of the mammalian SIM protein, we have isolated cDNA clones from a mouse embryo cDNA library. The cDNA clones encode a polypeptide of 657 amino acids with a bHLH (basic-helix-loop-helix) domain, characteristic of a large family of transcription factors, and a PAS (Per-Arnt-Sim) domain in the amino-terminal half region. Both of these domains have striking sequence homology with human SIM and Drosophila SIM proteins. In contrast, the carboxy-terminal half of the mouse SIM protein consists of a proline-rich region with no sequence homology to the Drosophila SIM provator domain of a number of transcription factors. Whole-mount embryo in situ hybridization experiments revealed that the SIM mRNA is expressed prominently in the diencephalon during embryogenesis strongly suggest that the newly isolated mammalian SIM homolog may play a critical role in the development of the mammalian central nervous system. We propose that the human SIM gene may be one of the pathogenic genes of Down syndrome. 36 refs., 6 figs.

Yamaki, Akiko [Keio Univ. School of Medicine, Tokyo (Japan)] [Keio Univ. School of Medicine, Tokyo (Japan); [Kyorin Univ., Tokyo (Japan); Kudoh, Jun; Shindoh, Nobuaki [Keio Univ. School of Medicine, Tokyo (Japan)] [and others] [Keio Univ. School of Medicine, Tokyo (Japan); and others



NeuroD1 mediates nicotine-induced migration and invasion via regulation of the nicotinic acetylcholine receptor subunits in a subset of neural and neuroendocrine carcinomas  

PubMed Central

Cigarette smoking is a major risk factor for acquisition of small cell lung cancer (SCLC). A role has been demonstrated for the basic helix-loop-helix transcription factor NeuroD1 in the pathogenesis of neural and neuroendocrine lung cancer, including SCLC. In the present study we investigate the possible function of NeuroD1 in established tumors, as well as actions early on in pathogenesis, in response to nicotine. We demonstrate that nicotine up-regulates NeuroD1 in immortalized normal bronchial epithelial cells and a subset of undifferentiated carcinomas. Increased expression of NeuroD1 subsequently leads to regulation of expression and function of the nicotinic acetylcholine receptor subunit cluster of ?3, ?5, and ?4. In addition, we find that coordinated expression of these subunits by NeuroD1 leads to enhanced nicotine-induced migration and invasion, likely through changes in intracellular calcium. These findings suggest that aspects of the pathogenesis of neural and neuroendocrine lung cancers may be affected by a nicotine- and NeuroD1-induced positive feedback loop. PMID:24719457

Osborne, Jihan K.; Guerra, Marcy L.; Gonzales, Joshua X.; McMillan, Elizabeth A.; Minna, John D.; Cobb, Melanie H.



Phylogenetic Analysis and Classification of the Fungal bHLH Domain  

PubMed Central

The basic Helix-Loop-Helix (bHLH) domain is an essential highly conserved DNA-binding domain found in many transcription factors in all eukaryotic organisms. The bHLH domain has been well studied in the Animal and Plant Kingdoms but has yet to be characterized within Fungi. Herein, we obtained and evaluated the phylogenetic relationship of 490 fungal-specific bHLH containing proteins from 55 whole genome projects composed of 49 Ascomycota and 6 Basidiomycota organisms. We identified 12 major groupings within Fungi (F1–F12); identifying conserved motifs and functions specific to each group. Several classification models were built to distinguish the 12 groups and elucidate the most discerning sites in the domain. Performance testing on these models, for correct group classification, resulted in a maximum sensitivity and specificity of 98.5% and 99.8%, respectively. We identified 12 highly discerning sites and incorporated those into a set of rules (simplified model) to classify sequences into the correct group. Conservation of amino acid sites and phylogenetic analyses established that like plant bHLH proteins, fungal bHLH–containing proteins are most closely related to animal Group B. The models used in these analyses were incorporated into a software package, the source code for which is available at PMID:22114358

Sailsbery, Joshua K.; Atchley, William R.; Dean, Ralph A.



SRY induced TCF21 genome-wide targets and cascade of bHLH factors during Sertoli cell differentiation and male sex determination in rats.  


Male sex determination is initiated through the testis-determining factor SRY that promotes Sertoli cell differentiation and subsequent gonadal development. The basic helix-loop-helix (bHLH) gene Tcf21 was identified as one of the direct downstream targets of SRY. The current study was designed to identify the downstream targets of TCF21 and the potential cascade of bHLH genes that promote Sertoli cell differentiation. A modified ChIP-Chip comparative hybridization analysis identified 121 direct downstream binding targets for TCF21. The gene networks and cellular pathways potentially regulated by these TCF21 targets were identified. One of the main bHLH targets for TCF21 was the bHLH gene scleraxis (Scx). An embryonic ovarian gonadal cell culture was used to examine the functional role of Sry, Tcf21, and Scx to promote an in vitro sex reversal and induction of Sertoli cell differentiation. SRY and TCF21 were found to induce the initial stages of Sertoli cell differentiation, whereas SCX was found to induce the later stages of Sertoli cell differentiation associated with pubertal development using transferrin gene expression as a marker. Therefore, a cascade of SRY followed by TCF21 followed by SCX appears to promote, in part, Sertoli cell fate determination and subsequent differentiation. The current observations help elucidate the initial molecular events involved in the induction of Sertoli cell differentiation and testis development. PMID:23034159

Bhandari, Ramji K; Schinke, Ellyn N; Haque, Md M; Sadler-Riggleman, Ingrid; Skinner, Michael K



Plant proximity perception dynamically modulates hormone levels and sensitivity in Arabidopsis  

PubMed Central

The shade avoidance syndrome (SAS) refers to a set of plant responses initiated after perception by the phytochromes of light enriched in far-red colour reflected from or filtered by neighbouring plants. These varied responses are aimed at anticipating eventual shading from potential competitor vegetation. In Arabidopsis thaliana, the most obvious SAS response at the seedling stage is the increase in hypocotyl elongation. Here, we describe how plant proximity perception rapidly and temporally alters the levels of not only auxins but also active brassinosteroids and gibberellins. At the same time, shade alters the seedling sensitivity to hormones. Plant proximity perception also involves dramatic changes in gene expression that rapidly result in a new balance between positive and negative factors in a network of interacting basic helix–loop–helix proteins, such as HFR1, PAR1, and BIM and BEE factors. Here, it was shown that several of these factors act as auxin- and BR-responsiveness modulators, which ultimately control the intensity or degree of hypocotyl elongation. It was deduced that, as a consequence of the plant proximity-dependent new, dynamic, and local balance between hormone synthesis and sensitivity (mechanistically resulting from a restructured network of SAS regulators), SAS responses are unleashed and hypocotyls elongate. PMID:24609653

Bou-Torrent, Jordi; Galstyan, Anahit; Gallemí, Marçal; Cifuentes-Esquivel, Nicolás; Molina-Contreras, Maria José; Salla-Martret, Mercè; Jikumaru, Yusuke; Yamaguchi, Shinjiro; Kamiya, Yuji; Martínez-García, Jaime F.



A DELLA in Disguise: SPATULA Restrains the Growth of the Developing Arabidopsis Seedling[C][W  

PubMed Central

The period following seedling emergence is a particularly vulnerable stage in the plant life cycle. In Arabidopsis thaliana, the phytochrome-interacting factor (PIF) subgroup of basic-helix-loop-helix transcription factors has a pivotal role in regulating growth during this early phase, integrating environmental and hormonal signals. We previously showed that SPATULA (SPT), a PIF homolog, regulates seed dormancy. In this article, we establish that unlike PIFs, which mainly promote hypocotyl elongation, SPT is a potent regulator of cotyledon expansion. Here, SPT acts in an analogous manner to the gibberellin-dependent DELLAs, REPRESSOR OF GA1-3 and GIBBERELLIC ACID INSENSITIVE, which restrain cotyledon expansion alongside SPT. However, although DELLAs are not required for SPT action, we demonstrate that SPT is subject to negative regulation by DELLAs. Cross-regulation of SPT by DELLAs ensures that SPT protein levels are limited when DELLAs are abundant but rise following DELLA depletion. This regulation provides a means to prevent excessive growth suppression that would result from the dual activity of SPT and DELLAs, yet maintain growth restraint under DELLA-depleted conditions. We present evidence that SPT and DELLAs regulate common gene targets and illustrate that the balance of SPT and DELLA action depends on light quality signals in the natural environment. PMID:21478445

Josse, Eve-Marie; Gan, Yinbo; Bou-Torrent, Jordi; Stewart, Kelly L.; Gilday, Alison D.; Jeffree, Christopher E.; Vaistij, Fabián E.; Martínez-García, Jaime F.; Nagy, Ferenc; Graham, Ian A.; Halliday, Karen J.



Targeted Deletion of the S-Phase-Specific Myc Antagonist Mad3 Sensitizes Neuronal and Lymphoid Cells to Radiation-Induced Apoptosis  

PubMed Central

The Mad family comprises four basic-helix-loop-helix/leucine zipper proteins, Mad1, Mxi1, Mad3, and Mad4, which heterodimerize with Max and function as transcriptional repressors. The balance between Myc-Max and Mad-Max complexes has been postulated to influence cell proliferation and differentiation. The expression patterns of Mad family genes are complex, but in general, the induction of most family members is linked to cell cycle exit and differentiation. The expression pattern of mad3 is unusual in that mad3 mRNA and protein were found to be restricted to proliferating cells prior to differentiation. We show here that during murine development mad3 is specifically expressed in the S phase of the cell cycle in neuronal progenitor cells that are committed to differentiation. To investigate mad3 function, we disrupted the mad3 gene by homologous recombination in mice. No defect in cell cycle exit and differentiation could be detected in mad3 homozygous mutant mice. However, upon gamma irradiation, increased cell death of thymocytes and neural progenitor cells was observed, implicating mad3 in the regulation of the cellular response to DNA damage. PMID:11154258

Quéva, Christophe; McArthur, Grant A.; Iritani, Brian M.; Eisenman, Robert N.



SIM2 maintains innate host defense of the small intestine.  


The single-minded 2 (SIM2) protein is a basic helix-loop-helix transcription factor regulating central nervous system (CNS) development in Drosophila. In humans, SIM2 is located within the Down syndrome critical region on chromosome 21 and may be involved in the development of mental retardation phenotype in Down syndrome. In this study, knockout of SIM2 expression in mice resulted in a gas distention phenotype in the gastrointestinal tract. We found that SIM2 is required for the expression of all cryptdins and numerous other antimicrobial peptides (AMPs) expressed in the small intestine. The mechanism underlying how SIM2 controls AMP expression involves both direct and indirect regulations. For the cryptdin genes, SIM2 regulates their expression by modulating transcription factor 7-like 2, a crucial regulator in the Wnt/?-catenin signaling pathway, while for other AMP genes, such as RegIII?, SIM2 directly activates their promoter activity. Our results establish that SIM2 is a crucial regulator in controlling expression of intestinal AMPs to maintain intestinal innate immunity against microbes. PMID:25277798

Chen, Kuan-Jung; Lizaso, Analyn; Lee, Ying-Hue



Development of inner ear afferent connections: forming primary neurons and connecting them to the developing sensory epithelia  

NASA Technical Reports Server (NTRS)

The molecular and cellular origin of the primary neurons of the inner ear, the vestibular and spiral neurons, is reviewed including how they connect to the specific sensory epithelia and what the molecular nature of their survival is. Primary neurons of the ear depend on a single basic Helix-Loop-Helix (bHLH) protein for their formation, neurogenin 1 (ngn1). An immediate downstream gene is the bHLH gene neuronal differentiation (NeuroD). Targeted null mutations of ngn1 results in absence of primary neuron formation; targeted null mutation of NeuroD results in loss of almost all spiral and many vestibular neurons. NeuroD and a later expressed gene, Brn3a, play a role in pathfinding to and within sensory epithelia. The molecular nature of this pathfinding property is unknown. Reduction of hair cells in ngn1 null mutations suggests a clonal relationship with primary neurons. This relationship may play some role in specifying the identity of hair cells and the primary neurons that connect with them. Primary neuron neurites growth to sensory epithelia is initially independent of trophic factors released from developing sensory epithelia, but becomes rapidly dependent on those factors. Null mutations of specific neurotrophic factors lose distinct primary neuron populations which undergo rapid embryonic cell death.

Fritzsch, Bernd



Transcriptional regulatory events initiated by ascl1 and neurog2 during neuronal differentiation of p19 embryonic carcinoma cells.  


As members of the proneural basic-helix-loop-helix (bHLH) family of transcription factors, Ascl1 and Neurog2 direct the differentiation of specific populations of neurons at various times and locations within the developing nervous system. In order to characterize the mechanisms employed by these two bHLH factors, we generated stable, doxycycline-inducible lines of P19 embryonic carcinoma cells that express comparable levels of Ascl1 and Neurog2. Upon induction, both Ascl1 and Neurog2 directed morphological and immunocytochemical changes consistent with initiation of neuronal differentiation. Comparison of Ascl1- and Neurog2-regulated genes by microarray analyses showed both shared and distinct transcriptional changes for each bHLH protein. In both Ascl1- and Neurog2-differentiating cells, repression of Oct4 mRNA levels was accompanied by increased Oct4 promoter methylation. However, DNA demethylation was not detected for genes induced by either bHLH protein. Neurog2-induced genes included glutamatergic marker genes while Ascl1-induced genes included GABAergic marker genes. The Neurog2-specific induction of a gene encoding a protein phosphatase inhibitor, Ppp1r14a, was dependent on distinct, canonical E-box sequences within the Ppp1r14a promoter and the nucleotide sequences within these E-boxes were partially responsible for Neurog2-specific regulation. Our results illustrate multiple novel mechanisms by which Ascl1 and Neurog2 regulate gene repression during neuronal differentiation in P19 cells. PMID:25189318

Huang, Holly S; Redmond, Tanya M; Kubish, Ginger M; Gupta, Shweta; Thompson, Robert C; Turner, David L; Uhler, Michael D



Characterization of the neural stem cell gene regulatory network identifies OLIG2 as a multifunctional regulator of self-renewal.  


The gene regulatory network (GRN) that supports neural stem cell (NS cell) self-renewal has so far been poorly characterized. Knowledge of the central transcription factors (TFs), the noncoding gene regulatory regions that they bind to, and the genes whose expression they modulate will be crucial in unlocking the full therapeutic potential of these cells. Here, we use DNase-seq in combination with analysis of histone modifications to identify multiple classes of epigenetically and functionally distinct cis-regulatory elements (CREs). Through motif analysis and ChIP-seq, we identify several of the crucial TF regulators of NS cells. At the core of the network are TFs of the basic helix-loop-helix (bHLH), nuclear factor I (NFI), SOX, and FOX families, with CREs often densely bound by several of these different TFs. We use machine learning to highlight several crucial regulatory features of the network that underpin NS cell self-renewal and multipotency. We validate our predictions by functional analysis of the bHLH TF OLIG2. This TF makes an important contribution to NS cell self-renewal by concurrently activating pro-proliferation genes and preventing the untimely activation of genes promoting neuronal differentiation and stem cell quiescence. PMID:25294244

Mateo, Juan L; van den Berg, Debbie L C; Haeussler, Maximilian; Drechsel, Daniela; Gaber, Zachary B; Castro, Diogo S; Robson, Paul; Crawford, Gregory E; Flicek, Paul; Ettwiller, Laurence; Wittbrodt, Joachim; Guillemot, François; Martynoga, Ben



Dynamic expression and roles of Hes factors in neural development.  


The basic helix-loop-helix factors Hes1 and Hes5 repress the expression of proneural factors such as Ascl1, thereby inhibiting neuronal differentiation and maintaining neural progenitor cells (NPCs). Hes1 expression oscillates by negative feedback with a period of about 2-3 h in proliferating NPCs. Induction of sustained expression of Hes1 in NPCs inhibits their cell-cycle progression, suggesting that the oscillatory expression of Hes1 is important for the proliferation of NPCs. Hes1 oscillation drives the oscillatory expression of proneural factors such as Ascl1 by periodic repression. By contrast, in differentiating neurons, Hes1 expression disappears and the expression of proneural factors is up-regulated and sustained. A new optogenetics approach that induces Ascl1 expression by blue light illumination demonstrated that sustained expression of Ascl1 induces neuronal differentiation, whereas oscillatory expression of Ascl1 activates the proliferation of NPCs. These results together indicate that Hes1 regulates the oscillatory versus sustained expression of the proneural factor Ascl1, which in turn regulates the proliferation of NPCs and the subsequent processes of cell-cycle exit and neuronal fate determination, depending on the expression dynamics. PMID:24850276

Kageyama, Ryoichiro; Shimojo, Hiromi; Imayoshi, Itaru



Regulation of leaf maturation by chromatin-mediated modulation of cytokinin responses.  


Plant shoots display indeterminate growth, while their evolutionary decedents, the leaves, are determinate. Determinate leaf growth is conditioned by the CIN-TCP transcription factors, which promote leaf maturation and are negatively regulated by miR319 in leaf primordia. Here we show that CIN-TCPs reduce leaf sensitivity to cytokinin (CK), a phytohormone implicated in inhibition of differentiation in the shoot. We identify the SWI/SNF chromatin remodeling ATPase BRAHMA (BRM) as a genetic mediator of CIN-TCP activities and CK responses. An interactome screen further revealed that SWI/SNF complex components including BRM preferentially interacted with basic-helix-loop-helix (bHLH) transcription factors and the bHLH-related CIN-TCPs. Indeed, TCP4 and BRM interacted in planta. Both TCP4 and BRM bound the promoter of an inhibitor of CK responses, ARR16, and induced its expression. Reconstituting ARR16 levels in leaves with reduced CIN-TCP activity restored normal growth. Thus, CIN-TCP and BRM together promote determinate leaf growth by stage-specific modification of CK responses. PMID:23449474

Efroni, Idan; Han, Soon-Ki; Kim, Hye Jin; Wu, Miin-Feng; Steiner, Evyatar; Birnbaum, Kenneth D; Hong, Jong Chan; Eshed, Yuval; Wagner, Doris



Vsx2 in the zebrafish retina: restricted lineages through derepression  

PubMed Central

Background The neurons in the vertebrate retina arise from multipotent retinal progenitor cells (RPCs). It is not clear, however, which progenitors are multipotent or why they are multipotent. Results In this study we show that the homeodomain transcription factor Vsx2 is initially expressed throughout the retinal epithelium, but later it is downregulated in all but a minor population of bipolar cells and all Müller glia. The Vsx2-negative daughters of Vsx2-positive RPCs divide and give rise to all other cell types in the retina. Vsx2 is a repressor whose targets include transcription factors such as Vsx1, which is expressed in the progenitors of distinct non-Vsx2 bipolars, and the basic helix-loop-helix transcription factor Ath5, which restricts the fate of progenitors to retinal ganglion cells, horizontal cells, amacrine cells and photoreceptors fates. Foxn4, expressed in the progenitors of amacrine and horizontal cells, is also negatively regulated by Vsx2. Conclusion Our data thus suggest Vsx2-positive RPCs are fully multipotent retinal progenitors and that when Vsx2 is downregulated, Vsx2-negative progenitors escape Vsx2 repression and so are able to express factors that restrict lineage potential. PMID:19344499

Vitorino, Marta; Jusuf, Patricia R; Maurus, Daniel; Kimura, Yukiko; Higashijima, Shin-ichi; Harris, William A



Slow transition between two ?-strand registers is dictated by protein unfolding  

PubMed Central

The aryl hydrocarbon receptor nuclear translocator (ARNT) is a promiscuous, basic helix-loop-helix Period/ARNT/Single-minded protein that forms dimeric transcriptional regulator complexes with other bHLH-PAS proteins to regulate various biological pathways. Intriguingly, the introduction of a single point mutation into the C-terminal PAS-B domain resulted in a protein that can simultaneously exist in two distinct conformations. The difference between these two structures is a +3 slip and inversion of a central I?-strand and an accompanying N448-P449 peptide bond isomerization in the preceding HI loop. Previous studies have indicated these two forms of Y456T interconvert on the approximate timescale of tens of minutes, allowing these two conformations to be separated by ion exchange chromatography. Here, we use time-resolved solution NMR spectroscopy to quantitatively characterize this rate and its temperature dependence, providing information into the transition state. When compared with fluorescence measurements of protein unfolding rates, we find data that suggest a linkage between interconversion and unfolding based on comparable temperature dependence and corresponding energetics of these processes. Notably, the N448-P449 peptide bond also plays a critical role for the interconversion between states, with a mutant unable to adopt a cis configuration at this bond (P449A/Y456T) being kinetically trapped under non-denaturing conditions. Taken together, these data provide information about a rare equilibrium model system for ?-strand slippage. PMID:19722642

Evans, Matthew R.; Gardner, Kevin H.



ARNT PAS-B has a fragile native state structure with an alternative ?-sheet register nearby in sequence space  

PubMed Central

The aryl hydrocarbon receptor nuclear translocator (ARNT) is a basic helix–loop–helix Period/ARNT/Single-minded (bHLH-PAS) protein that controls various biological pathways as part of dimeric transcriptional regulator complexes with other bHLH-PAS proteins. The two PAS domains within ARNT, PAS-A and PAS-B, are essential for the formation of these complexes because they mediate protein–protein interactions via residues located on their ?-sheet surfaces. While investigating the importance of residues in ARNT PAS-B involved in these interactions, we uncovered a point mutation (Y456T) on the solvent-exposed ?-sheet surface that allowed this domain to interconvert with a second, stable conformation. Although both conformations are present in equivalent quantities in the Y456T mutant, this can be shifted almost completely to either end point by additional mutations. A high-resolution solution structure of a mutant ARNT PAS-B domain stabilized in the new conformation revealed a 3-residue slip in register and accompanying inversion of the central I?-strand. We have demonstrated that the new conformation has >100-fold lower in vitro affinity for its heterodimerization partner, hypoxia-inducible factor 2? PAS-B. We speculate that the pliability in ?-strand register is related to the flexibility required of ARNT to bind to several partners and, more broadly, to the abilities of some PAS domains to regulate their activities in response to small-molecule cofactors. PMID:19196990

Evans, Matthew R.; Card, Paul B.; Gardner, Kevin H.



The Zinc Finger Transcription Factor RP58 Negatively Regulates Rnd2 for the Control of Neuronal Migration During Cerebral Cortical Development.  


The zinc finger transcription factor RP58 (also known as ZNF238) regulates neurogenesis of the mouse neocortex and cerebellum (Okado et al. 2009; Xiang et al. 2011; Baubet et al. 2012; Ohtaka-Maruyama et al. 2013), but its mechanism of action remains unclear. In this study, we report a cell-autonomous function for RP58 during the differentiation of embryonic cortical projection neurons via its activities as a transcriptional repressor. Disruption of RP58 expression alters the differentiation of immature neurons and impairs their migration and positioning within the mouse cerebral cortex. Loss of RP58 within the embryonic cortex also leads to elevated mRNA for Rnd2, a member of the Rnd family of atypical RhoA-like GTPase proteins important for cortical neuron migration (Heng et al. 2008). Mechanistically, RP58 represses transcription of Rnd2 via binding to a 3'-regulatory enhancer in a sequence-specific fashion. Using reporter assays, we found that RP58 repression of Rnd2 is competed by proneural basic helix-loop-helix transcriptional activators. Finally, our rescue experiments revealed that negative regulation of Rnd2 by RP58 was important for cortical cell migration in vivo. Taken together, these studies demonstrate that RP58 is a key player in the transcriptional control of cell migration in the developing cerebral cortex. PMID:24084125

Heng, Julian Ik-Tsen; Qu, Zhengdong; Ohtaka-Maruyama, Chiaki; Okado, Haruo; Kasai, Masataka; Castro, Diogo; Guillemot, François; Tan, Seong-Seng



Genetic interaction between Kit and Scl  

PubMed Central

SCL/TAL1, a tissue-specific transcription factor of the basic helix-loop-helix family, and c-Kit, a tyrosine kinase receptor, control hematopoietic stem cell survival and quiescence. Here we report that SCL levels are limiting for the clonal expansion of Kit+ multipotent and erythroid progenitors. In addition, increased SCL expression specifically enhances the sensitivity of these progenitors to steel factor (KIT ligand) without affecting interleukin-3 response, whereas a DNA-binding mutant antagonizes KIT function and induces apoptosis in progenitors. Furthermore, a twofold increase in SCL levels in mice bearing a hypomorphic Kit allele (W41/41) corrects their hematocrits and deficiencies in erythroid progenitor numbers. At the molecular level, we found that SCL and c-Kit signaling control a common gene expression signature, of which 19 genes are associated with apoptosis. Half of those were decreased in purified megakaryocyte/erythroid progenitors (MEPs) from W41/41 mice and rescued by the SCL transgene. We conclude that Scl operates downstream of Kit to support the survival of MEPs. Finally, higher SCL expression upregulates Kit in normal bone marrow cells and increases chimerism after bone marrow transplantation, indicating that Scl is also upstream of Kit. We conclude that Scl and Kit establish a positive feedback loop in multipotent and MEPs. PMID:23836559

Lacombe, Julie; Krosl, Gorazd; Tremblay, Mathieu; Gerby, Bastien; Martin, Richard; Aplan, Peter D.; Lemieux, Sebastien



An evolutionarily acquired genotoxic response discriminates MyoD from Myf5, and differentially regulates hypaxial and epaxial myogenesis.  


Despite having distinct expression patterns and phenotypes in mutant mice, the myogenic regulatory factors Myf5 and MyoD have been considered to be functionally equivalent. Here, we report that these factors have a different response to DNA damage, due to the presence in MyoD and absence in Myf5 of a consensus site for Abl-mediated tyrosine phosphorylation that inhibits MyoD activity in response to DNA damage. Genotoxins failed to repress skeletal myogenesis in MyoD-null embryos; reintroduction of wild-type MyoD, but not mutant Abl phosphorylation-resistant MyoD, restored the DNA-damage-dependent inhibition of muscle differentiation. Conversely, introduction of the Abl-responsive phosphorylation motif converts Myf5 into a DNA-damage-sensitive transcription factor. Gene-dosage-dependent reduction of Abl kinase activity in MyoD-expressing cells attenuated the DNA-damage-dependent inhibition of myogenesis. The presence of a DNA-damage-responsive phosphorylation motif in vertebrate, but not in invertebrate MyoD suggests an evolved response to environmental stress, originated from basic helix-loop-helix gene duplication in vertebrate myogenesis. PMID:21212806

Innocenzi, Anna; Latella, Lucia; Messina, Graziella; Simonatto, Marta; Marullo, Fabrizia; Berghella, Libera; Poizat, Coralie; Shu, Chih-Wen; Wang, Jean Y J; Puri, Pier Lorenzo; Cossu, Giulio



TFE3 inhibits myoblast differentiation in C2C12 cells via down-regulating gene expression of myogenin.  


Transcription factor E3 (TFE3) belongs to a basic helix-loop-helix family, and is involved in the biology of osteoclasts, melanocytes and their malignancies. We previously reported the metabolic effects of TFE3 on insulin in the liver and skeletal muscles in animal models. In the present study, we explored a novel role for TFE3 in a skeletal muscle cell line. When TFE3 was overexpressed in C2C12 myoblasts by adenovirus before induction of differentiation, myogenic differentiation of C2C12 cells was significantly inhibited. Adenovirus-mediated TFE3 overexpression also suppressed the gene expression of muscle regulatory factors (MRFs), such as MyoD and myogenin, during C2C12 differentiation. In contrast, knockdown of TFE3 using adenovirus encoding short-hairpin RNAi specific for TFE3 dramatically promoted myoblast differentiation associated with significantly increased expression of MRFs. Consistent with these findings, promoter analyses via luciferase reporter assay and electrophoretic mobility shift assay suggested that TFE3 negatively regulated myogenin promoter activity by direct binding to an E-box, E2, in the myogenin promoter. These findings indicated that TFE3 has a regulatory role in myoblast differentiation, and that transcriptional suppression of myogenin expression may be part of the mechanism of action. PMID:23211595

Naka, Ayano; Iida, Kaoruko Tada; Nakagawa, Yoshimi; Iwasaki, Hitoshi; Takeuchi, Yoshinori; Satoh, Aoi; Matsuzaka, Takashi; Ishii, Kiyo-Aki; Kobayashi, Kazuto; Yatoh, Shigeru; Shimada, Masako; Yahagi, Naoya; Suzuki, Hiroaki; Sone, Hirohito; Yamada, Nobuhiro; Shimano, Hitoshi



G9a mediates Sharp-1-dependent inhibition of skeletal muscle differentiation.  


Sharp-1, a basic helix-loop-helix transcription factor, is a potent repressor of skeletal muscle differentiation and is dysregulated in muscle pathologies. However, the mechanisms by which it inhibits myogenesis are not fully understood. Here we show that G9a, a lysine methyltransferase, is involved in Sharp-1-mediated inhibition of muscle differentiation. We demonstrate that G9a directly interacts with Sharp-1 and enhances its ability to transcriptionally repress the myogenin promoter. Concomitant with a differentiation block, G9a-dependent histone H3 lysine 9 dimethylation (H3K9me2) and MyoD methylation are apparent upon Sharp-1 overexpression in muscle cells. RNA interference-mediated reduction of G9a or pharmacological inhibition of its activity erases these repressive marks and rescues the differentiation defect imposed by Sharp-1. Our findings provide new insights into Sharp-1-dependent regulation of myogenesis and identify epigenetic mechanisms that could be targeted in myopathies characterized by elevated Sharp-1 levels. PMID:23087213

Ling, Belinda Mei Tze; Gopinadhan, Suma; Kok, Wai Kay; Shankar, Shilpa Rani; Gopal, Pooja; Bharathy, Narendra; Wang, Yaju; Taneja, Reshma



Gating of the rapid shade-avoidance response by the circadian clock in plants.  


The phytochromes are a family of plant photoreceptor proteins that control several adaptive developmental strategies. For example, the phytochromes perceive far-red light (wavelengths between 700 and 800 nm) reflected or scattered from the leaves of nearby vegetation. This provides an early warning of potential shading, and triggers a series of 'shade-avoidance' responses, such as a rapid increase in elongation, by which the plant attempts to overgrow its neighbours. Other, less immediate, responses include accelerated flowering and early production of seeds. However, little is known about the molecular events that connect light perception with increased growth in shade avoidance. Here we show that the circadian clock gates this rapid shade-avoidance response. It is most apparent around dusk and is accompanied by altered expression of several genes. One of these rapidly responsive genes encodes a basic helix-loop-helix protein, PIL1, previously shown to interact with the clock protein TOC1 (ref. 4). Furthermore PIL1 and TOC1 are both required for the accelerated growth associated with the shade-avoidance response. PMID:14668869

Salter, Michael G; Franklin, Keara A; Whitelam, Garry C



Molecular Characterisation, Evolution and Expression of Hypoxia-Inducible Factor in Aurelia sp.1  

PubMed Central

The maintenance of physiological oxygen homeostasis is mediated by hypoxia-inducible factor (HIF), a key transcriptional factor of the PHD-HIF system in all metazoans. However, the molecular evolutionary origin of this central physiological regulatory system is not well characterized. As the earliest eumetazoans, Cnidarians can be served as an interesting model for exploring the HIF system from an evolutionary perspective. We identified the complete cDNA sequence of HIF-1? (ASHIF) from the Aurelia sp.1, and the predicted HIF-1? protein (pASHIF) was comprised of 674 amino acids originating from 2,025 bp nucleotides. A Pairwise comparison revealed that pASHIF not only possessed conserved basic helix-loop-helix (bHLH) and Per-Arnt-Sim (PAS) domains but also contained the oxygen dependent degradation (ODD) and the C-terminal transactivation domains (C-TAD), the key domains for hypoxia regulation. As indicated by sequence analysis, the ASHIF gene contains 8 exons interrupted by 7 introns. Western blot analysis indicated that pASHIF that existed in the polyps and medusa of Aurelia. sp.1 was more stable for a hypoxic response than normoxia. PMID:24926666

Wang, Guoshan; Yu, Zhigang; Zhen, Yu; Mi, Tiezhu; Shi, Yan; Wang, Jianyan; Wang, Minxiao; Sun, Song



MITF mutations associated with pigment deficiency syndromes and melanoma have different effects on protein function.  


The basic-helix-loop-helix-leucine zipper (bHLHZip) protein MITF (microphthalmia-associated transcription factor) is a master regulator of melanocyte development. Mutations in the MITF have been found in patients with the dominantly inherited hypopigmentation and deafness syndromes Waardenburg syndrome type 2A (WS2A) and Tietz syndrome (TS). Additionally, both somatic and germline mutations have been found in MITF in melanoma patients. Here, we characterize the DNA-binding and transcription activation properties of 24 MITF mutations found in WS2A, TS and melanoma patients. We show that most of the WS2A and TS mutations fail to bind DNA and activate expression from melanocyte-specific promoters. Some of the mutations, especially R203K and S298P, exhibit normal activity and may represent neutral variants. Mutations found in melanomas showed normal DNA-binding and minor variations in transcription activation properties; some showed increased potential to form colonies. Our results provide molecular insights into how mutations in a single gene can lead to such different phenotypes. PMID:23787126

Grill, Christine; Bergsteinsdóttir, Kristín; Ogmundsdóttir, Margrét H; Pogenberg, Vivian; Schepsky, Alexander; Wilmanns, Matthias; Pingault, Veronique; Steingrímsson, Eiríkur



Identification of candidate genes underlying an iron efficiency quantitative trait locus in soybean.  


Prevalent on calcareous soils in the United States and abroad, iron deficiency is among the most common and severe nutritional stresses in plants. In soybean (Glycine max) commercial plantings, the identification and use of iron-efficient genotypes has proven to be the best form of managing this soil-related plant stress. Previous studies conducted in soybean identified a significant iron efficiency quantitative trait locus (QTL) explaining more than 70% of the phenotypic variation for the trait. In this research, we identified candidate genes underlying this QTL through molecular breeding, mapping, and transcriptome sequencing. Introgression mapping was performed using two related near-isogenic lines in which a region located on soybean chromosome 3 required for iron efficiency was identified. The region corresponds to the previously reported iron efficiency QTL. The location was further confirmed through QTL mapping conducted in this study. Transcriptome sequencing and quantitative real-time-polymerase chain reaction identified two genes encoding transcription factors within the region that were significantly induced in soybean roots under iron stress. The two induced transcription factors were identified as homologs of the subgroup lb basic helix-loop-helix (bHLH) genes that are known to regulate the strategy I response in Arabidopsis (Arabidopsis thaliana). Resequencing of these differentially expressed genes unveiled a significant deletion within a predicted dimerization domain. We hypothesize that this deletion disrupts the Fe-DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT)/bHLH heterodimer that has been shown to induce known iron acquisition genes. PMID:22319075

Peiffer, Gregory A; King, Keith E; Severin, Andrew J; May, Gregory D; Cianzio, Silvia R; Lin, Shun Fu; Lauter, Nicholas C; Shoemaker, Randy C



Degradation of the transcription factor Twist, an oncoprotein that promotes cancer metastasis.  


Basic helix-loop-helix (bHLH) transcription factor Twist is one of the key inducers of epithelial to mesenchymal transition (EMT) that is a transdifferentiation program associated with embryo development and tumor metastasis. High level of Twist expression is shown to be correlated with cancer malignancy. Although Twist has been reported to be degraded by F-box and leucine-rich repeat protein 14 (FBXL14), the molecular mechanisms by which Twist levels are regulated have not been fully elucidated. In the present study, we identified Twist to be a ubiquitin substrate of ?-transducin repeat-containing protein (?-TRCP), the adaptor subunit of SCF(?-TRCP) (Skp1-Cul1-F-box protein) E3 ligase complex. We observed that depletion of ?-TRCP leads to an accumulation of Twist protein, which could enhance tumor cell motility and cancer metastasis. Moreover, phosphorylation of Twist by inhibitor of KappaB kinase ? (IKK?) at multiple sites triggers its cytoplasmic translocation and the destruction by SCF(?-TRCP). Thus, our results provide the potential molecular mechanism of how the mesenchymal marker Twist is degraded, thereby shedding lights into regulation of the EMT, and providing the rationale for development of new therapeutic intervention to achieve better treatment outcomes in human cancer. PMID:23375009

Zhong, Jiateng; Ogura, Kohei; Wang, Zhiwei; Inuzuka, Hiroyuki



The mutational spectrum in Waardenburg syndrome  

SciTech Connect

101 individuals or families with Waardenburg syndrome (WS) or related abnormalities have been screened for mutations in the PAX3 gene. PAX3 mutations were seen in 19 of 35 individuals or families with features of Type I Waardenburg syndrome. None of the 47 Type 2 WS families showed any PAX3 mutation, nor did any of 19 individuals with other neural crest syndromes or pigmentary disturbances. PAX3 mutations included substitutions of highly conserved amino acids, splice site mutations, nonsense mutations and frameshifting deletions or insertions. One patient (with Type 1 WS, mental retardation and growth retardation) had a chromosomal deletion of 7-8 Mb encompassing the PAX3 gene. Mutations were seen in each of exons 2-6, with a concentration in the 5{prime} part of the paired box (exon 2) and the 3{prime} part of the homeobox (exon 6). There was no evident relation between the molecular change and the clinical manifestations in mutation carriers. We conclude that PAX3 dosage effects very specifically produce dystopia canthorum, the distinguishing feature of Type 1 WS, and variably produce the other features of Type 1 WS depending on genetic background or chance events. Two of the Type 2 families showed linkage to markers from 3p14, the location of the MITF gene. MITF encodes a basic helix-loop-helix-zipper protein which is the homologue of the mouse microphthalmia gene product. It is likely that mutations in MITF cause some but not all Type 2 WS.

Read, A.P.; Tassabehji, M.; Liu, X.Z. [and others



PIFs: Systems Integrators in Plant Development[W  

PubMed Central

Phytochrome-interacting factors (PIFs) are members of the Arabidopsis thaliana basic helix-loop-helix family of transcriptional regulators that interact specifically with the active Pfr conformer of phytochrome (phy) photoreceptors. PIFs are central regulators of photomorphogenic development that act to promote stem growth, and this activity is reversed upon interaction with phy in response to light. Recently, significant progress has been made in defining the transcriptional networks directly regulated by PIFs, as well as the convergence of other signaling pathways on the PIFs to modulate growth. Here, we summarize and highlight these findings in the context of PIFs acting as integrators of light and other signals. We discuss progress in our understanding of the transcriptional and posttranslational regulation of PIFs that illustrates the integration of light with hormonal pathways and the circadian clock, and we review seedling hypocotyl growth as a paradigm of PIFs acting at the interface of these signals. Based on these advances, PIFs are emerging as required factors for growth, acting as central components of a regulatory node that integrates multiple internal and external signals to optimize plant development. PMID:24481072

Leivar, Pablo; Monte, Elena



Can the 'neuron theory' be complemented by a universal mechanism for generic neuronal differentiation.  


With the establishment of the 'neuron theory' at the turn of the twentieth century, this remarkably powerful term was introduced to name a breathtaking diversity of cells unified by a characteristic structural compartmentalization and unique information processing and propagating features. At the beginning of the twenty-first century, developmental, stem cell and reprogramming studies converged to suggest a common mechanism involved in the generation of possibly all vertebrate, and at least a significant number of invertebrate, neurons. Sox and, in particular, SoxB and SoxC proteins as well as basic helix-loop-helix proteins play major roles, even though their precise contributions to progenitor programming, proliferation and differentiation are not fully resolved. In addition to neuronal development, these transcription factors also regulate sensory receptor and endocrine cell development, thus specifying a range of cells with regulatory and communicative functions. To what extent microRNAs contribute to the diversification of these cell types is an upcoming question. Understanding the transcriptional and post-transcriptional regulation of genes coding for cell type-specific cytoskeletal and motor proteins as well as synaptic and ion channel proteins, which mark differences but also similarities between the three communicator cell types, will provide a key to the comprehension of their diversification and the signature of 'generic neuronal' differentiation. Apart from the general scientific significance of a putative universal core instruction for neuronal development, the impact of this line of research for cell replacement therapy and brain tumor treatment will be of considerable interest. PMID:25429886

Ernsberger, Uwe



Integrated Expression Profiling and Genome-Wide Analysis of ChREBP Targets Reveals the Dual Role for ChREBP in Glucose-Regulated Gene Expression  

PubMed Central

The carbohydrate response element binding protein (ChREBP), a basic helix-loop-helix/leucine zipper transcription factor, plays a critical role in the control of lipogenesis in the liver. To identify the direct targets of ChREBP on a genome-wide scale and provide more insight into the mechanism by which ChREBP regulates glucose-responsive gene expression, we performed chromatin immunoprecipitation-sequencing and gene expression analysis. We identified 1153 ChREBP binding sites and 783 target genes using the chromatin from HepG2, a human hepatocellular carcinoma cell line. A motif search revealed a refined consensus sequence (CABGTG-nnCnG-nGnSTG) to better represent critical elements of a functional ChREBP binding sequence. Gene ontology analysis shows that ChREBP target genes are particularly associated with lipid, fatty acid and steroid metabolism. In addition, other functional gene clusters related to transport, development and cell motility are significantly enriched. Gene set enrichment analysis reveals that ChREBP target genes are highly correlated with genes regulated by high glucose, providing a functional relevance to the genome-wide binding study. Furthermore, we have demonstrated that ChREBP may function as a transcriptional repressor as well as an activator. PMID:21811631

Lee, Yong Seok; Kim, Ha-Jung; Han, Jung-Youn; Im, Seung-Soon; Chong, Hansook Kim; Kwon, Je-Keun; Cho, Yun-Ho; Kim, Woo Kyung; Osborne, Timothy F.; Horton, Jay D.; Jun, Hee-Sook; Ahn, Yong-Ho; Ahn, Sung-Min; Cha, Ji-Young



Ligand-binding properties of a juvenile hormone receptor, Methoprene-tolerant.  


Juvenile hormone (JH) is a sesquiterpenoid of vital importance for insect development, yet the molecular basis of JH signaling remains obscure, mainly because a bona fide JH receptor has not been identified. Mounting evidence points to the basic helix-loop-helix (bHLH)/Per-Arnt-Sim (PAS) domain protein Methoprene-tolerant (Met) as the best JH receptor candidate. However, details of how Met transduces the hormonal signal are missing. Here, we demonstrate that Met specifically binds JH III and its biologically active mimics, methoprene and pyriproxyfen, through its C-terminal PAS domain. Substitution of individual amino acids, predicted to form a ligand-binding pocket, with residues possessing bulkier side chains reduces JH III binding likely because of steric hindrance. Although a mutation that abolishes JH III binding does not affect a Met-Met complex that forms in the absence of methoprene, it prevents both the ligand-dependent dissociation of the Met-Met dimer and the ligand-dependent interaction of Met with its partner bHLH-PAS protein Taiman. These results show that Met can sense the JH signal through direct, specific binding, thus establishing a unique class of intracellular hormone receptors. PMID:22167806

Charles, Jean-Philippe; Iwema, Thomas; Epa, V Chandana; Takaki, Keiko; Rynes, Jan; Jindra, Marek



The SCL gene specifies haemangioblast development from early mesoderm.  

PubMed Central

The SCL gene encodes a basic helix-loop-helix (bHLH) transcription factor that is essential for the development of all haematopoietic lineages. SCL is also expressed in endothelial cells, but its function is not essential for specification of endothelial progenitors and the role of SCL in endothelial development is obscure. We isolated the zebrafish SCL homologue and show that it was co-expressed in early mesoderm with markers of haematopoietic, endothelial and pronephric progenitors. Ectopic expression of SCL mRNA in zebrafish embryos resulted in overproduction of common haematopoietic and endothelial precursors, perturbation of vasculogenesis and concomitant loss of pronephric duct and somitic tissue. Notochord and neural tube formation were unaffected. These results provide the first evidence that SCL specifies formation of haemangioblasts, the proposed common precursor of blood and endothelial lineages. Our data also underline the striking similarities between the role of SCL in haematopoiesis/vasculogenesis and the function of other bHLH proteins in muscle and neural development. PMID:9670018

Gering, M; Rodaway, A R; Göttgens, B; Patient, R K; Green, A R



COP1 and phyB Physically Interact with PIL1 to Regulate Its Stability and Photomorphogenic Development in Arabidopsis.  


In Arabidopsis thaliana, the cryptochrome and phytochrome photoreceptors act together to promote photomorphogenic development. The cryptochrome and phytochrome signaling mechanisms interact directly with CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1), a RING motif-containing E3 ligase that acts to negatively regulate photomorphogenesis. COP1 interacts with and ubiquitinates the transcription factors that promote photomorphogenesis, such as ELONGATED HYPOCOTYL5 and LONG HYPOCOTYL IN FAR-RED1 (HFR1), to inhibit photomorphogenic development. Here, we show that COP1 physically interacts with PIF3-LIKE1 (PIL1) and promotes PIL1 degradation via the 26S proteasome. We further demonstrate that phyB physically interacts with PIL1 and enhances PIL1 protein accumulation upon red light irradiation, probably through suppressing the COP1-PIL1 association. Biochemical and genetic studies indicate that PIL1 and HFR1 form heterodimers and promote photomorphogenesis cooperatively. Moreover, we demonstrate that PIL1 interacts with PIF1, 3, 4, and 5, resulting in the inhibition of the transcription of PIF direct-target genes. Our results reveal that PIL1 stability is regulated by phyB and COP1, likely through physical interactions, and that PIL1 coordinates with HFR1 to inhibit the transcriptional activity of PIFs, suggesting that PIL1, HFR1, and PIFs constitute a subset of antagonistic basic helix-loop-helix factors acting downstream of phyB and COP1 to regulate photomorphogenic development. PMID:24951480

Luo, Qian; Lian, Hong-Li; He, Sheng-Bo; Li, Ling; Jia, Kun-Peng; Yang, Hong-Quan



Myrosin idioblast cell fate and development are regulated by the Arabidopsis transcription factor FAMA, the auxin pathway, and vesicular trafficking.  


Crucifer shoots harbor a glucosinolate-myrosinase system that defends against insect predation. Arabidopsis thaliana myrosinase (thioglucoside glucohydrolase [TGG]) accumulates in stomata and in myrosin idioblasts (MIs). This work reports that the basic helix-loop-helix transcription factor FAMA that is key to stomatal development is also expressed in MIs. The loss of FAMA function abolishes MI fate as well as the expression of the myrosinase genes TGG1 and TGG2. MI cells have previously been reported to be located in the phloem. Instead, we found that MIs arise from the ground meristem rather than provascular tissues and thus are not homologous with phloem. Moreover, MI patterning and morphogenesis are abnormal when the function of the ARF-GEF gene GNOM is lost as well as when auxin efflux and vesicular trafficking are chemically disrupted. Stomata and MI cells constitute part of a wider system that reduces plant predation, the so-called "mustard oil bomb," in which vacuole breakage in cells harboring myrosinase and glucosinolate yields a brew toxic to many animals, especially insects. This identification of the gene that confers the fate of MIs, as well as stomata, might facilitate the development of strategies for engineering crops to mitigate predation. PMID:25304201

Li, Meng; Sack, Fred D



MITF mutations associated with pigment deficiency syndromes and melanoma have different effects on protein function  

PubMed Central

The basic-helix–loop–helix-leucine zipper (bHLHZip) protein MITF (microphthalmia-associated transcription factor) is a master regulator of melanocyte development. Mutations in the MITF have been found in patients with the dominantly inherited hypopigmentation and deafness syndromes Waardenburg syndrome type 2A (WS2A) and Tietz syndrome (TS). Additionally, both somatic and germline mutations have been found in MITF in melanoma patients. Here, we characterize the DNA-binding and transcription activation properties of 24 MITF mutations found in WS2A, TS and melanoma patients. We show that most of the WS2A and TS mutations fail to bind DNA and activate expression from melanocyte-specific promoters. Some of the mutations, especially R203K and S298P, exhibit normal activity and may represent neutral variants. Mutations found in melanomas showed normal DNA-binding and minor variations in transcription activation properties; some showed increased potential to form colonies. Our results provide molecular insights into how mutations in a single gene can lead to such different phenotypes. PMID:23787126

Grill, Christine; Bergsteinsdóttir, Kristín; Ögmundsdóttir, Margrét H.; Pogenberg, Vivian; Schepsky, Alexander; Wilmanns, Matthias; Pingault, Veronique; Steingrímsson, Eiríkur



Up-regulation of the Sirtuin 1 (Sirt1) and peroxisome proliferator-activated receptor ? coactivator-1? (PGC-1?) genes in white adipose tissue of Id1 protein-deficient mice: implications in the protection against diet and age-induced glucose intolerance.  


Id1, a helix-loop-helix (HLH) protein that inhibits the function of basic HLH E protein transcription factors in lymphoid cells, has been implicated in diet- and age-induced obesity by unknown mechanisms. Here we show that Id1-deficient mice are resistant to a high fat diet- and age-induced obesity, as revealed by reduced weight gain and body fat, increased lipid oxidation, attenuated hepatosteatosis, lower levels of lipid droplets in brown adipose tissue, and smaller white adipocytes after a high fat diet feeding or in aged animals. Id1 deficiency improves glucose tolerance, lowers serum insulin levels, and reduces TNF? gene expression in white adipose tissue. Id1 deficiency also increased expression of Sirtuin 1 and peroxisome proliferator-activated receptor ? coactivator 1?, regulators of mitochondrial biogenesis and energy expenditure, in the white adipose tissue. This effect was accompanied by the elevation of several genes encoding proteins involved in oxidative phosphorylation and fatty acid oxidation, such as cytochrome c, medium-chain acyl-CoA dehydrogenase, and adipocyte protein 2. Moreover, the phenotype for Id1 deficiency was similar to that of mice expressing an E protein dominant-positive construct, ET2, suggesting that the balance between Id and E proteins plays a role in regulating lipid metabolism and insulin sensitivity. PMID:25190816

Zhao, Ying; Ling, Flora; Griffin, Timothy M; He, Ting; Towner, Rheal; Ruan, Hong; Sun, Xiao-Hong



Generation of Atoh1-rtTA transgenic mice: a tool for inducible gene expression in hair cells of the inner ear  

PubMed Central

Atoh1 is a basic helix-loop-helix transcription factor that controls differentiation of hair cells (HCs) in the inner ear and its enhancer region has been used to create several HC-specific mouse lines. We generated a transgenic tetracycline-inducible mouse line (called Atoh1-rtTA) using the Atoh1 enhancer to drive expression of the reverse tetracycline transactivator (rtTA) protein and human placental alkaline phosphatase. Presence of the transgene was confirmed by alkaline phosphatase staining and rtTA activity was measured using two tetracycline operator (TetO) reporter alleles with doxycycline administered between postnatal days 0–3. This characterization of five founder lines demonstrated that Atoh1-rtTA is expressed in the majority of cochlear and utricular HCs. Although the tetracycline-inducible system is thought to produce transient changes in gene expression, reporter positive HCs were still observed at 6 weeks of age. To confirm that Atoh1-rtTA activity was specific to Atoh1-expressing cells, we also analyzed the cerebellum and found rtTA-driven reporter expression in cerebellar granule neuron precursor cells. The Atoh1-rtTA mouse line provides a powerful tool for the field and can be used in combination with other existing Cre recombinase mouse lines to manipulate expression of multiple genes at different times in the same animal. PMID:25363458

Cox, Brandon C.; Dearman, Jennifer A.; Brancheck, Joseph; Zindy, Frederique; Roussel, Martine F.; Zuo, Jian



Dual-mode Modulation of Smad Signaling by Smad-interacting Protein Sip1 is Required for Myelination in the CNS  

PubMed Central

Myelination by oligodendrocytes in the central nervous system (CNS) is essential for proper brain function, yet the molecular determinants that control this process remain poorly understood. The basic helix-loop-helix transcription factors Olig1 and Olig2 promote myelination, whereas bone morphogenetic protein (BMP) and Wnt/?-catenin signaling inhibit myelination. Here we show that these opposing regulators of myelination are functionally linked by the Olig1/2 common target Smad-interacting protein-1 (Sip1). We demonstrate that Sip1 is an essential modulator of CNS myelination. Sip1 represses differentiation inhibitory signals by antagonizing BMP receptor activated-Smad activity while activating crucial oligodendrocyte-promoting factors. Importantly, a key Sip1-activated target, Smad7, is required for oligodendrocyte differentiation, and partially rescues differentiation defects caused by Sip1 loss. Smad7 promotes myelination by blocking the BMP and ?-catenin negative regulatory pathways. Thus, our findings reveal that Sip1-mediated antagonism of inhibitory signaling is critical for promoting CNS myelination and point to new mediators for myelin repair. PMID:22365546

Weng, Qinjie; Chen, Ying; Wang, Haibo; Xu, Xiaomei; Yang, Bo; He, Qiaojun; Shou, Weinian; Chen, Yan; Higashi, Yujiro; van den Berghe, Veronique; Seuntjens, Eve; Kernie, Steven G.; Bukshpun, Polina; Sherr, Elliott H.; Huylebroeck, Danny; Lu, Q. Richard



Daughterless homodimer synergizes with Eyeless to induce Atonal expression and retinal neuron differentiation.  


Class I Basic Helix-Loop-Helix (bHLH) transcription factors form homodimers or heterodimers with class II bHLH proteins. While bHLH heterodimers are known to have diverse roles, little is known about the role of class I homodimers. In this manuscript, we show that a linked dimer of Daughterless (Da), the only Drosophila class I bHLH protein, activates Atonal (Ato) expression and retinal neuron differentiation synergistically with the retinal determination factor Eyeless (Ey). The HLH protein Extramacrocheate (Emc), which forms heterodimer with Da, antagonizes the synergistic activation from Da but not the Da-Da linked dimer with Ey. We show that Da directly interacts with Ey and promotes Ey binding to the Ey binding site in the Ato 3? enhancer. Interestingly, the Ey binding site in the Ato 3? enhancer contains an embedded E-box that is also required for the synergistic activation by Ey and Da. Finally we show that mammalian homologs of Ey and Da can functionally replace their Drosophila counterparts to synergistically activate the Ato enhancer, suggesting that the observed function is evolutionary conserved. PMID:24886829

Tanaka-Matakatsu, Miho; Miller, John; Borger, Daniel; Tang, Wei-Jen; Du, Wei



Deletion mapping in the Enhancer of split complex.  


The Enhancer of split complex [E(spl)-C] comprises twelve genes of different classes. Seven genes encode proteins of with a basic-helix-loop-helix-orange (bHLH-O) domain that function as transcriptional repressors and serve as effectors of the Notch signalling pathway. They have been named E(spl)m8-, m7-, m5-, m3-, m?-, m?- and m?-HLH. Four genes, E(spl)m6-, m4-, m2- and m?-BFM are intermingled and encode Notch repressor proteins of the Bearded-family (BFM). The complex is split by a single gene of unrelated function, encoding a Kazal-type protease inhibitor (Kaz-m1). All members within a family, bHLH-O or BFM, are very similar in structure and in function. In an attempt to generate specific mutants, we have mobilised P-element constructs residing next to E(spl)m7-HLH and E(spl)m?-HLH, respectively. The resulting deletions were mapped molecularly and by cytology. Two small deletions affected only E(spl)m7-HLH and E(spl)m?. The deficient flies were viable without apparent phenotype. Larger deletions, generated also by X-ray mutagenesis, uncover most of the E(spl)-C. The phenotypes of homozygous deficient embryos were analysed to characterize the respective loss of Notch signalling activity. PMID:25588303

Wurmbach, Elisa; Preiss, Anette



Diversity in the utilization of glucose and lactate in synthetic mammalian myotubes generated by engineered configurations of MyoD and E12 in otherwise non-differentiation growth conditions.  


We previously used the expression of various combinations and configurations of MyoD and E12, two basic helix-loop-helix transcription factors (TF), to produce populations of myotubes assuming distinct morphology, myofibrillar development and Ca(2+) dynamics, from mammalian C2C12 myoblasts in non-differentiation growth conditions. Here, we assessed the synthetically generated myotubes in terms of energetics, otherwise necessary to sustain their mechanical output as bio-actuators. We found that the myotubes exhibit changed expression of key regulators for the uptake and utilization of two major cellular fuels, glucose and lactate. Furthermore, while lactate transport was uniformly slowed in all the populations of myotubes, glucose uptake and utilization were modified by particular TF configuration. Our approach allows the production of a class of biomaterials with predetermined energetics that could be applied in biorobotics, where fuel of choice could be used, and also in reparative medicine where, for example, particular population of myotubes could be additionally employed as glucose sinks to mitigate effects of secondary metabolic syndrome. PMID:25591961

Grubiši?, Vladimir; Parpura, Vladimir



Coordinated transcriptional regulation of isopentenyl diphosphate biosynthetic pathway enzymes in plastids by phytochrome-interacting factor 5.  


All isoprenoids are derived from a common C5 unit, isopentenyl diphosphate (IPP). In plants, IPP is synthesized via two distinct pathways; the cytosolic mevalonate pathway and the plastidial non-mevalonate (MEP) pathway. In this study, we used a co-expression analysis to identify transcription factors that coordinately regulate the expression of multiple genes encoding enzymes in the IPP biosynthetic pathway. Some candidates showed especially strong correlations with multiple genes encoding MEP-pathway enzymes. We report here that phytochrome-interacting factor 5 (PIF5), a basic-helix-loop-helix type transcription factor, functions as a positive regulator of the MEP pathway. Its overexpression in T87 suspension cultured cells resulted in increased accumulation of chlorophylls and carotenoids. Detailed analyses of carotenoids by HPLC indicated that some carotenoid biosynthetic pathways were concomitantly up-regulated, possibly as a result of enhanced IPP metabolic flow. Our results also revealed other PIF family proteins that play different roles from that of PIF5 in IPP metabolism. PMID:24342623

Mannen, Kazuto; Matsumoto, Takuro; Takahashi, Seiji; Yamaguchi, Yuta; Tsukagoshi, Masanori; Sano, Ryosuke; Suzuki, Hideyuki; Sakurai, Nozomu; Shibata, Daisuke; Koyama, Tanetoshi; Nakayama, Toru



Neurogenin3 triggers beta-cell differentiation of retinoic acid-derived endoderm cells.  

PubMed Central

Neurogenin3 is a member of the basic helix-loop-helix ('bHLH') family of transcription factors. It plays a crucial role in the commitment of embryonic endoderm into the pancreatic differentiation programme. This factor is considered to act upstream of a cascade of other transcription factors, leading to the fully differentiated endocrine phenotype. Direct observation of the sequential activation of these factors starting from Neurogenin3 had never been demonstrated. By using retinoic acid-derived-endoderm F9 cells as a model, the present study indicates that the ectopic expression of Neurogenin3 is able to start the differentiation pathway of endocrine pancreas. Neurogenin3 triggers the expression of several pancreatic transcription factors following a well defined temporal activation sequence. By reverse transcriptase PCR, immunohistochemistry and RIA, it is shown that stable transfected cells are able to form embryod bodies that produce insulin in response to glucose stimulation. This is the first report of a differentiation event induced by the ectopic expression of a transcription factor in embryonic pluripotent stem cells. PMID:12529176

Vetere, Amedeo; Marsich, Eleonora; Di Piazza, Matteo; Koncan, Raffaella; Micali, Fulvio; Paoletti, Sergio



Soybean SAT1 (Symbiotic Ammonium Transporter 1) encodes a bHLH transcription factor involved in nodule growth and NH4+ transport  

PubMed Central

Glycine max symbiotic ammonium transporter 1 was first documented as a putative ammonium (NH4+) channel localized to the symbiosome membrane of soybean root nodules. We show that Glycine max symbiotic ammonium transporter 1 is actually a membrane-localized basic helix–loop–helix (bHLH) DNA-binding transcription factor now renamed Glycine max bHLH membrane 1 (GmbHLHm1). In yeast, GmbHLHm1 enters the nucleus and transcriptionally activates a unique plasma membrane NH4+ channel Saccharomyces cerevisiae ammonium facilitator 1. Ammonium facilitator 1 homologs are present in soybean and other plant species, where they often share chromosomal microsynteny with bHLHm1 loci. GmbHLHm1 is important to the soybean rhizobium symbiosis because loss of activity results in a reduction of nodule fitness and growth. Transcriptional changes in nodules highlight downstream signaling pathways involving circadian clock regulation, nutrient transport, hormone signaling, and cell wall modification. Collectively, these results show that GmbHLHm1 influences nodule development and activity and is linked to a novel mechanism for NH4+ transport common to both yeast and plants. PMID:24707045

Chiasson, David M.; Loughlin, Patrick C.; Mazurkiewicz, Danielle; Mohammadidehcheshmeh, Manijeh; Fedorova, Elena E.; Okamoto, Mamoru; McLean, Elizabeth; Glass, Anthony D. M.; Smith, Sally E.; Bisseling, Ton; Tyerman, Stephen D.; Day, David A.; Kaiser, Brent N.



Silencing of the EPHB3 tumor-suppressor gene in human colorectal cancer through decommissioning of a transcriptional enhancer  

PubMed Central

The protein tyrosine kinase Ephrin type-B receptor 3 (EPHB3) counteracts tumor-cell dissemination by regulating intercellular adhesion and repulsion and acts as tumor/invasion suppressor in colorectal cancer. This protective mechanism frequently collapses at the adenoma–carcinoma transition due to EPHB3 transcriptional silencing. Here, we identify a transcriptional enhancer at the EPHB3 gene that integrates input from the intestinal stem-cell regulator achaete-scute family basic helix-loop-helix transcription factor 2 (ASCL2), Wnt/?-catenin, MAP kinase, and Notch signaling. EPHB3 enhancer activity is highly variable in colorectal carcinoma cells and precisely reflects EPHB3 expression states, suggesting that enhancer dysfunction underlies EPHB3 silencing. Interestingly, low Notch activity parallels reduced EPHB3 expression in colorectal carcinoma cell lines and poorly differentiated tumor-tissue specimens. Restoring Notch activity reestablished enhancer function and EPHB3 expression. Although essential for intestinal stem-cell maintenance and adenoma formation, Notch activity seems dispensable in colorectal carcinomas. Notch activation even promoted growth arrest and apoptosis of colorectal carcinoma cells, attenuated their self-renewal capacity in vitro, and blocked tumor growth in vivo. Higher levels of Notch activity also correlated with longer disease-free survival of colorectal cancer patients. In summary, our results uncover enhancer decommissioning as a mechanism for transcriptional silencing of the EPHB3 tumor suppressor and argue for an antitumorigenic function of Notch signaling in advanced colorectal cancer. PMID:24707046

Jägle, Sabine; Rönsch, Kerstin; Timme, Sylvia; Andrlová, Hana; Bertrand, Miriam; Jäger, Marcel; Proske, Amelie; Schrempp, Monika; Yousaf, Afsheen; Michoel, Tom; Zeiser, Robert; Werner, Martin; Lassmann, Silke; Hecht, Andreas



Spatial distribution and function of sterol regulatory element-binding protein 1a and 2 homo- and heterodimers by in vivo two-photon imaging and spectroscopy fluorescence resonance energy transfer.  


Sterol regulatory element-binding proteins (SREBPs) are a subfamily of basic helix-loop-helix-leucine zipper proteins that regulate lipid metabolism. We show novel evidence of the in vivo occurrence and subnuclear spatial localization of both exogenously expressed SREBP-1a and -2 homodimers and heterodimers obtained by two-photon imaging and spectroscopy fluorescence resonance energy transfer. SREBP-1a homodimers localize diffusely in the nucleus, whereas SREBP-2 homodimers and the SREBP-1a/SREBP-2 heterodimer localize predominantly to nuclear speckles or foci, with some cells showing a diffuse pattern. We also used tethered SREBP dimers to demonstrate that both homo- and heterodimeric SREBPs activate transcription in vivo. Ultrastructural analysis revealed that the punctate foci containing SREBP-2 are electron-dense nuclear bodies, similar or identical to structures containing the promyelocyte (PML) protein. Immunofluorescence studies suggest that a dynamic interplay exists between PML, as well as another component of the PML-containing nuclear body, SUMO-1, and SREBP-2 within these nuclear structures. These findings provide new insight into the overall process of transcriptional activation mediated by the SREBP family. PMID:15798184

Zoumi, Aikaterini; Datta, Shrimati; Liaw, Lih-Huei L; Wu, Cristen J; Manthripragada, Gopi; Osborne, Timothy F; Lamorte, Vickie J



The rice tapetum degeneration retardation gene is required for tapetum degradation and anther development.  


In flowering plants, tapetum degeneration is proposed to be triggered by a programmed cell death (PCD) process during late stages of pollen development; the PCD is thought to provide cellular contents supporting pollen wall formation and to allow the subsequent pollen release. However, the molecular basis regulating tapetum PCD in plants remains poorly understood. We report the isolation and characterization of a rice (Oryza sativa) male sterile mutant tapetum degeneration retardation (tdr), which exhibits degeneration retardation of the tapetum and middle layer as well as collapse of microspores. The TDR gene is preferentially expressed in the tapetum and encodes a putative basic helix-loop-helix protein, which is likely localized to the nucleus. More importantly, two genes, Os CP1 and Os c6, encoding a Cys protease and a protease inhibitor, respectively, were shown to be the likely direct targets of TDR through chromatin immunoprecipitation analyses and the electrophoretic mobility shift assay. These results indicate that TDR is a key component of the molecular network regulating rice tapetum development and degeneration. PMID:17138695

Li, Na; Zhang, Da-Sheng; Liu, Hai-Sheng; Yin, Chang-Song; Li, Xiao-xing; Liang, Wan-qi; Yuan, Zheng; Xu, Ben; Chu, Huang-Wei; Wang, Jia; Wen, Tie-Qiao; Huang, Hai; Luo, Da; Ma, Hong; Zhang, Da-Bing



Differential responsiveness of distinct retinal domains to Atoh7  

PubMed Central

During vertebrate eye development retinal progenitor cells (RPCs) differentiate into all neural cell types of the retina. Retinal ganglion cells (RGCs) represent the first cell type to be generated. For their development, Atoh7, a basic Helix Loop Helix (bHLH) transcription factor is crucial. Atoh7 loss of function results in a massive reduction or even a total loss of RGCs. However, inconsistent results have been obtained in atoh7 gain of function experiments with respect to ganglion cell genesis, implying that the effect of Atoh7 is likely to be dependent on the competence state of the RPC. In this study we addressed the differential susceptibilities of early RPCs to Atoh7 in vivo, using medaka. Unexpectedly, we observed a largely normal development of the dorsal retina, although atoh7 was precociously expressed. However, the development of the retina close to the optic nerve head (part of the ventral retina) was disturbed severely. Photoreceptors were largely absent and the Müller glia cell number was reduced significantly. The majority of cells in this domain were ganglion cells and the abnormal development of this area affected the closure of the optic fissure resulting in coloboma. PMID:25151399

Sinn, Rebecca; Peravali, Ravindra; Heermann, Stephan; Wittbrodt, Joachim



Brassinosteroid Signaling Pathway  

NSDL National Science Digital Library

Plant growth is regulated by an intricate network of hormonal signaling pathways. These small-molecule hormones cause changes in gene expression that are associated with cell expansion and division and changes in development. Paradoxically, six of these hormones appear to have largely overlapping functions, yet the loss of response to any one hormone cannot be compensated by the action of another plant hormone. Among these hormones are the brassinosteroids (BRs), the polyhydroxylated steroid hormones of plants. The emerging picture of BR signal transduction diverges radically from the paradigms of animal steroid signaling, which generally involve the action of members of the nuclear receptor superfamily. BRs bind the extracellular domain of a small family of leucine-rich-repeat receptor kinases to activate intracellular signal transduction cascades that regulate the expression of hundreds of genes. The signaling pathway involves a cell surface receptor complex, a glycogen synthase kinase 3, a kelch-containing serine/threonine phosphatase, and a novel family of basic helix-loop-helix and Myc-like plant specific transcription factors. The receptor and each of the signaling components were identified in Arabidopsis thaliana, and knowledge of their sequences allowed identification of orthologs in rice, tomato, barley, and pea.

Youssef Belkhadir (The Salk Institute;Plant Biology Laboratory REV); Xuelu Wang (The Salk Institute;Plant Biology Laboratory REV); Joanne Chory (The Salk Institute;Plant Biology Laboratory REV)



Zac1 Regulates Cell Cycle Arrest in Neuronal Progenitors via Tcf4  

PubMed Central

Imprinted genes play a critical role in brain development and mental health, although the underlying molecular and cellular mechanisms remain incompletely understood. The family of basic helix-loop-helix (bHLH) proteins directs the proliferation, differentiation, and specification of distinct neuronal progenitor populations. Here, we identified the bHLH factor gene Tcf4 as a direct target gene of Zac1/Plagl1, a maternally imprinted transcriptional regulator, during early neurogenesis. Zac1 and Tcf4 expression levels concomitantly increased during neuronal progenitor differentiation; moreover, Zac1 interacts with two cis-regulatory elements in the Tcf4 gene locus, and these elements together confer synergistic activation of the Tcf4 gene. Tcf4 upregulation enhances the expression of the cyclin-dependent kinase inhibitor gene p57Kip2, a paternally imprinted Tcf4 target gene, and increases the number of cells in G1 phase. Overall, we show that Zac1 controls cell cycle arrest function in neuronal progenitors through induction of p57Kip2 via Tcf4 and provide evidence for cooperation between imprinted genes and a bHLH factor in early neurodevelopment. PMID:24396065

Schmidt-Edelkraut, Udo; Daniel, Guillaume; Hoffmann, Anke



Generation of a germ cell-specific mouse transgenic CHERRY reporter, Sohlh1-mCherryFlag  

PubMed Central

SUMMARY Visualization of differentiating germ cells is critical to understanding the formation of primordial follicles in the ovary, and the commitment of spermatogonial stem cells to differentiation. We engineered and generated a BAC transgenic mouse line, Sohlh1-mCherryFlag (S1CF), under the direction of the native Sohlh1 promoter. Sohlh1 is a germ cell-specific gene that encodes the basic helix-loop-helix (bHLH) transcriptional regulator that is essential in oogenesis and spermatogenesis. Sohlh1 expression is unique, and is limited to perinatal and early follicle oocytes and differentiating spermatogonia. The Sohlh1-mCherryFlag transgene was engineered to fuse SOHLH1 to the red fluorescent protein CHERRY with 3-tandem-FLAG tags. S1CF animals fluoresce specifically in the oocytes of perinatal ovaries and small follicles in adult ovaries, as well as in spermatogonia, a pattern that is similar to endogenous SOHLH1. Moreover, S1CF rescued germ cell loss and infertility in both male and female Sohlh1?/? animals. The FLAG-tag on S1CF was effective for immunostaining and immunoprecipitation. The Sohlh1-mCherryFlag transgenic mouse provides a unique model to study early germ cell differentiation, as well as in vivo imaging and purification of differentiating germ cells. PMID:22965810

Suzuki, Hitomi; Dann, Christina Tenenhaus; Rajkovic, Aleksandar



Chimeric Restriction Enzymes: What Is Next?  

PubMed Central

Chimeric restriction enzymes are a novel class of engineered nucleases in which the non-specific DNA cleavage domain of FokI (a type IIS restriction endonuclease) is fused to other DNA-binding motifs. The latter include the three common eukaryotic DNA-binding motifs, namely the helix-turn-helix motif, the zinc finger motif and the basic helix-loop-helix protein containing a leucine zipper motif. Such chimeric nucleases have been shown to make specific cuts in vitro very close to the expected recognition sequences. The most important chimeric nucleases are those based on zinc finger DNA-binding proteins because of their modular structure. Recently, one such chimeric nuclease, Zif-QQR-FN was shown to find and cleave its target in vivo. This was tested by microinjection of DNA substrates and the enzyme into frog oocytes (Carroll et al., 1999). The injected enzyme made site-specific double-strand breaks in the targets even after assembly of the DNA into chromatin. In addition, this cleavage activated the target molecules for efficient homologous recombination. Since the recognition specificity of zinc fingers can be manipulated experimentally, chimeric nucleases could be engineered so as to target a specific site within a genome. The availability of such engineered chimeric restriction enzymes should make it feasible to do genome engineering, also commonly referred to as gene therapy. PMID:10494832

Smith, Jeff



Enhancer mutations of Akv murine leukemia virus inhibit the induction of mature B-cell lymphomas and shift disease specificity towards the more differentiated plasma cell stage  

SciTech Connect

This study investigates the role of the proviral transcriptional enhancer for B-lymphoma induction by exogenous Akv murine leukemia virus. Infection of newborn inbred NMRI mice with Akv induced 35% plasma cell proliferations (PCPs) (consistent with plasmacytoma), 33% diffuse large B-cell lymphomas, 25% follicular B-cell lymphomas and few splenic marginal zone and small B-cell lymphomas. Deleting one copy of the 99-bp proviral enhancer sequence still allowed induction of multiple B-cell tumor types, although PCPs dominated (77%). Additional mutation of binding sites for the glucocorticoid receptor, Ets, Runx, or basic helix-loop-helix transcription factors in the proviral U3 region, however, shifted disease induction to almost exclusively PCPs, but had no major influence on tumor latency periods. Southern analysis of immunoglobulin rearrangements and ecotropic provirus integration patterns showed that many of the tumors/cell proliferations induced by each virus were polyclonal. Our results indicate that enhancer mutations weaken the ability of Akv to induce mature B-cell lymphomas prior to the plasma cell stage, whereas development of plasma cell proliferations is less dependent of viral enhancer strength.

Sorensen, Karina Dalsgaard [Department of Molecular Biology, University of Aarhus, C.F. Mollers Alle, Bldg. 130, DK-8000 Aarhus C (Denmark); Kunder, Sandra [Institute of Pathology, GSF-National Research Center for Environment and Health, Neuherberg (Germany); Quintanilla-Martinez, Leticia [Institute of Pathology, GSF-National Research Center for Environment and Health, Neuherberg (Germany); Sorensen, Jonna [Department of Comparative Medicine, GSF-National Research Center for Environment and Health, Neuherberg (Germany); Schmidt, Joerg [Department of Comparative Medicine, GSF-National Research Center for Environment and Health, Neuherberg (Germany); Pedersen, Finn Skou [Department of Molecular Biology, University of Aarhus, C.F. Mollers Alle, Bldg. 130, DK-8000 Aarhus C (Denmark)]. E-mail:



Assignment of the human MAD and MXI1 genes to chromosomes 2p12-p13 and 10q24-q25  

SciTech Connect

MAD and MXI1, two recently described members of the basic helix-loop-helix (bHLH) gene family, encode proteins that dimerize with and modulate the DNA binding of max. In turn, mad-max or mxi1-max heterodimers or max homodimers can compete for DNA binding sites with dimers formed between max and myc oncoproteins and antagonize the transcriptional activities of this latter class of proteins. Using a combination of somatic cell mapping and fluorescence in situ hybridization techniques, we have determined the chromosomal locations of the MAD and MXI1 genes. The MAD gene maps to chromosome 2p12-p13, a region involved in translocations and deletions in acute and chronic lymphocytic leukemias as well as nonlymphocytic leukemias and Hodgkin disease. The MXI1 gene localizes to chromosome 10q24-q25, a region involved in translocations and deletions in acute and chronic lymphocytic leukemias and prostatic carcinomas. The availability of genomic clones of MAD and MXI1 will permit an assessment of their involvement in these diseases at the molecular level. 23 refs., 1 fig.

Shapiro, D.N. [St. Jude Children`s Hospital, Memphis, TN (United States)] [St. Jude Children`s Hospital, Memphis, TN (United States); [Univ. of Tennessee College of Medicine, Memphis, TN (United States); Eagle, L.; Yin, X. [Children`s Hospital of Pittsburgh, PA (United States)] [and others] [Children`s Hospital of Pittsburgh, PA (United States); and others



MondoA deficiency enhances sprint performance in mice.  


MondoA is a basic helix-loop-helix (bHLH)/leucine zipper (ZIP) transcription factor that is expressed predominantly in skeletal muscle. Studies in vitro suggest that the Max-like protein X (MondoA:Mlx) heterodimer senses the intracellular energy status and directly targets the promoter region of thioredoxin interacting protein (Txnip) and possibly glycolytic enzymes. We generated MondoA-inactivated (MondoA-/-) mice by gene targeting. MondoA-/- mice had normal body weight at birth, exhibited normal growth and appeared to be healthy. However, they exhibited unique metabolic characteristics. MondoA-/- mice built up serum lactate and alanine levels and utilized fatty acids for fuel during exercise. Gene expression and promoter analysis suggested that MondoA functionally represses peroxisome-proliferator-activated receptor ? co-activator-1? (PGC-1?)-mediated activation of pyruvate dehydrogenase kinase 4 (PDK-4) transcription. PDK4 normally down-regulates the activity of pyruvate dehydrogenase, an enzyme complex that catalyses the decarboxylation of pyruvate to acetyl-CoA for entry into the Krebs cycle; in the absence of MondoA, pyruvate is diverted towards lactate and alanine, both products of glycolysis. Dynamic testing revealed that MondoA-/- mice excel in sprinting as their skeletal muscles display an enhanced glycolytic capacity. Our studies uncover a hitherto unappreciated function of MondoA in fuel selection in vivo. Lack of MondoA results in enhanced exercise capacity with sprinting. PMID:25145386

Imamura, Minako; Chang, Benny Hung-Junn; Kohjima, Motoyuki; Li, Ming; Hwang, Byounghoon; Taegtmeyer, Heinrich; Harris, Robert A; Chan, Lawrence



Characterization of human variants in obesity-related SIM1 protein identifies a hot-spot for dimerization with the partner protein ARNT2.  


The bHLH (basic helix-loop-helix) PAS (Per/Arnt/Sim) transcription factor SIM1 (single-minded 1) is important for development and function of regions of the hypothalamus that regulate energy homoeostasis and the feeding response. Low-activity SIM1 variants have been identified in individuals with severe early-onset obesity, but the underlying molecular causes of impaired function are unknown. In the present study we assess a number of human SIM1 variants with reduced activity and determine that impaired function is frequently due to defects in dimerization with the essential partner protein ARNT2 (aryl hydrocarbon nuclear translocator 2). Equivalent variants generated in the highly related protein SIM2 (single-minded 2) produce near-identical impaired function and dimerization defects, indicating that these effects are not unique to the structure of SIM1. On the basis of these data, we predict that other select SIM1 and SIM2 variants reported in human genomic databases will also be deficient in activity, and identify two new low-activity SIM1 variants (V290E and V326F) present in the population. The cumulative data is used in homology modelling to make novel observations about the dimerization interface between the PAS domains of SIM1 and ARNT2, and to define a mutational 'hot-spot' in SIM1 that is critical for protein function. PMID:24814368

Sullivan, Adrienne E; Raimondo, Anne; Schwab, Tanja A; Bruning, John B; Froguel, Philippe; Farooqi, I Sadaf; Peet, Daniel J; Whitelaw, Murray L



Requirement for Lyl1 in a model of Lmo2-driven early T-cell precursor ALL.  


Lmo2 is an oncogenic transcription factor that is frequently overexpressed in T-cell acute lymphoblastic leukemia (T-ALL), including early T-cell precursor ALL (ETP-ALL) cases with poor prognosis. Lmo2 must be recruited to DNA by binding to the hematopoietic basic helix-loop-helix factors Scl/Tal1 or Lyl1. However, it is unknown which of these factors can mediate the leukemic activity of Lmo2. To address this, we have generated Lmo2-transgenic mice lacking either Scl or Lyl1 in the thymus. We show that although Scl is dispensable for Lmo2-driven leukemia, Lyl1 is critical for all oncogenic functions of Lmo2, including upregulation of a stem cell-like gene signature, aberrant self-renewal of thymocytes, and subsequent generation of T-cell leukemia. Lyl1 expression is restricted to preleukemic and leukemic stem cell populations in this model, providing a molecular explanation for the stage-specific expression of the Lmo2-induced gene expression program. Moreover, LMO2 and LYL1 are coexpressed in ETP-ALL patient samples, and LYL1 is required for growth of ETP-ALL cell lines. Thus, the LMO2-LYL1 interaction is a promising therapeutic target for inhibiting self-renewing cancer stem cells in T-ALL, including poor-prognosis ETP-ALL cases. PMID:23926305

McCormack, Matthew P; Shields, Benjamin J; Jackson, Jacob T; Nasa, Chayanica; Shi, Wei; Slater, Nicholas J; Tremblay, Cedric S; Rabbitts, Terence H; Curtis, David J



Multidirectional Differentiation of Achaete–Scute Homologue–1–Defined Progenitors in Lung Development and Injury Repair  

PubMed Central

Multiple cells contribute to the function of lungs. Pulmonary neuroendocrine cells (PNECs) are important for the regulation of breathing and carcinogenesis, although they represent only a small population of the airway lining. Achaete–Scute homologue–1 (Ascl1), a proneural basic helix–loop–helix transcription factor, is critical for the development of PNECs. We postulated that Ascl1-defined cells (ASDCs) may be progenitors, and traced their fate during development and injury repair. R26R-stop-lacZ (Rosa) reporter mice were crossed with Ascl1-Cre or Ascl1-CreERTM mice, in which the Ascl1 promoter drives the expression of Cre or inducible Cre recombinase, respectively. ASDCs and their descendants will be permanently labeled. The labeled cells were characterized by immunohistochemistry, using highly specific differentiation markers. Lineage studies revealed a population that proliferates before the pseudoglandular stage, and widely contributes to different compartments. When ASDCs were labeled on Embryonic Day 9.5, they gave rise to both airway and alveolar cells, but when labeled on Embryonic Day 11.5, they only gave rise to airway cells. In postnatal naphthalene injury, ASDCs contributed to regenerating Clara cells. In conclusion, Ascl1-defined cells in the lung represent a novel multipotent lineage, indicating a close relationship of neuroendocrine cells with other cell types. PMID:22878413

Li, Yan



Soybean SAT1 (Symbiotic Ammonium Transporter 1) encodes a bHLH transcription factor involved in nodule growth and NH4+ transport.  


Glycine max symbiotic ammonium transporter 1 was first documented as a putative ammonium (NH4(+)) channel localized to the symbiosome membrane of soybean root nodules. We show that Glycine max symbiotic ammonium transporter 1 is actually a membrane-localized basic helix-loop-helix (bHLH) DNA-binding transcription factor now renamed Glycine max bHLH membrane 1 (GmbHLHm1). In yeast, GmbHLHm1 enters the nucleus and transcriptionally activates a unique plasma membrane NH4(+) channel Saccharomyces cerevisiae ammonium facilitator 1. Ammonium facilitator 1 homologs are present in soybean and other plant species, where they often share chromosomal microsynteny with bHLHm1 loci. GmbHLHm1 is important to the soybean rhizobium symbiosis because loss of activity results in a reduction of nodule fitness and growth. Transcriptional changes in nodules highlight downstream signaling pathways involving circadian clock regulation, nutrient transport, hormone signaling, and cell wall modification. Collectively, these results show that GmbHLHm1 influences nodule development and activity and is linked to a novel mechanism for NH4(+) transport common to both yeast and plants. PMID:24707045

Chiasson, David M; Loughlin, Patrick C; Mazurkiewicz, Danielle; Mohammadidehcheshmeh, Manijeh; Fedorova, Elena E; Okamoto, Mamoru; McLean, Elizabeth; Glass, Anthony D M; Smith, Sally E; Bisseling, Ton; Tyerman, Stephen D; Day, David A; Kaiser, Brent N



Modes of Retrotransposition of Long Interspersed Element-1 by Environmental Factors  

PubMed Central

Approximately 42% of the human genome is composed of endogenous retroelements, and the major retroelement component, long interspersed element-1 (L1), comprises ?17% of the total genome. A single human cell has more than 5?×?105 copies of L1, 80?100 copies of which are competent for retrotransposition (RTP). Notably, L1 can induce RTP of other retroelements, such as Alu and SVA, and is believed to function as a driving force of evolution. Although L1-RTP during early embryogenesis has been highlighted in the literature, recent observations revealed that L1-RTP also occurs in somatic cells. However, little is known about how environmental factors induce L1-RTP. Here, we summarize our current understanding of the mechanism of L1-RTP in somatic cells. We have focused on the mode of L1-RTP that is dependent on the basic helix–loop–helix/per–arnt–sim (bHLH/PAS) family of transcription factors. Along with the proposed function of bHLH/PAS proteins in environmental adaptation, we discuss the functional linking of L1-RTP and bHLH/PAS proteins for environmental adaptation and evolution. PMID:22666219

Ishizaka, Yukihito; Okudaira, Noriyuki; Tamura, Masato; Iijima, Kenta; Shimura, Mari; Goto, Motohito; Okamura, Tadashi



?-Catenin Is Required for Hair-Cell Differentiation in the Cochlea  

PubMed Central

The development of hair cells in the auditory system can be separated into steps; first, the establishment of progenitors for the sensory epithelium, and second, the differentiation of hair cells. Although the differentiation of hair cells is known to require the expression of basic helix-loop-helix transcription factor, Atoh1, the control of cell proliferation in the region of the developing cochlea that will ultimately become the sensory epithelium and the cues that initiate Atoh1 expression remain obscure. We assessed the role of Wnt/?-catenin in both steps in gain- and loss-of-function models in mice. The canonical Wnt pathway mediator, ?-catenin, controls the expression of Atoh1. Knock-out of ?-catenin inhibited hair-cell, as well as pillar-cell, differentiation from sensory progenitors but was not required to maintain a hair-cell fate once specified. Constitutive activation of ?-catenin expanded sensory progenitors by inducing additional cell division and resulted in the differentiation of extra hair cells. Our data demonstrate that ?-catenin plays a role in cell division and differentiation in the cochlear sensory epithelium. PMID:24806673

Hu, Lingxiang; Jacques, Bonnie E.; Mulvaney, Joanna F.; Dabdoub, Alain



HLH54F is required for the specification and migration of longitudinal gut muscle founders from the caudal mesoderm of Drosophila  

PubMed Central

HLH54F, the Drosophila ortholog of the vertebrate basic helix-loop-helix domain-encoding genes capsulin and musculin, is expressed in the founder cells and developing muscle fibers of the longitudinal midgut muscles. These cells descend from the posterior-most portion of the mesoderm, termed the caudal visceral mesoderm (CVM), and migrate onto the trunk visceral mesoderm prior to undergoing myoblast fusion and muscle fiber formation. We show that HLH54F expression in the CVM is regulated by a combination of terminal patterning genes and snail. We generated HLH54F mutations and show that this gene is crucial for the specification, migration and survival of the CVM cells and the longitudinal midgut muscle founders. HLH54F mutant embryos, larvae, and adults lack all longitudinal midgut muscles, which causes defects in gut morphology and integrity. The function of HLH54F as a direct activator of gene expression is exemplified by our analysis of a CVM-specific enhancer from the Dorsocross locus, which requires combined inputs from HLH54F and Biniou in a feed-forward fashion. We conclude that HLH54F is the earliest specific regulator of CVM development and that it plays a pivotal role in all major aspects of development and differentiation of this largely twist-independent population of mesodermal cells. PMID:20736287

Ismat, Afshan; Schaub, Christoph; Reim, Ingolf; Kirchner, Katharina; Schultheis, Dorothea; Frasch, Manfred



ULTRAPETALA trxG Genes Interact with KANADI Transcription Factor Genes to Regulate Arabidopsis Gynoecium Patterning[C][W][OPEN  

PubMed Central

Organ formation relies upon precise patterns of gene expression that are under tight spatial and temporal regulation. Transcription patterns are specified by several cellular processes during development, including chromatin remodeling, but little is known about how chromatin-remodeling factors contribute to plant organogenesis. We demonstrate that the trithorax group (trxG) gene ULTRAPETALA1 (ULT1) and the GARP transcription factor gene KANADI1 (KAN1) organize the Arabidopsis thaliana gynoecium along two distinct polarity axes. We show that ULT1 activity is required for the kan1 adaxialized polarity defect, indicating that ULT1 and KAN1 act oppositely to regulate the adaxial-abaxial axis. Conversely, ULT1 and KAN1 together establish apical-basal polarity by promoting basal cell fate in the gynoecium, restricting the expression domain of the basic helix-loop-helix transcription factor gene SPATULA. Finally, we show that ult alleles display dose-dependent genetic interactions with kan alleles and that ULT and KAN proteins can associate physically. Our findings identify a dual role for plant trxG factors in organ patterning, with ULT1 and KAN1 acting antagonistically to pattern the adaxial-abaxial polarity axis but jointly to pattern the apical-basal axis. Our data indicate that the ULT proteins function to link chromatin-remodeling factors with DNA binding transcription factors to regulate target gene expression. PMID:25381352

Monfared, Mona M.; Shemyakina, Elena A.; Fletcher, Jennifer C.



Evolution of a genomic regulatory domain: The role of gene co-option and gene duplication in the Enhancer of split complex  

PubMed Central

The Drosophila Enhancer of split complex [E(spl)-C] is a remarkable complex of genes many of which are effectors or modulators of Notch signaling. The complex contains different classes of genes including four bearded genes and seven basic helix-loop-helix (bHLH) genes. We examined the evolution of this unusual complex by identifying bearded and bHLH genes in the genome sequences of Arthropods. We find that a four-gene E(spl)-C, containing three bHLH genes and one bearded gene, is an ancient component of the genomes of Crustacea and Insects. The complex is well conserved in insects but is highly modified in Drosophila, where two of the ancestral genes of the complex are missing, and the remaining two have been duplicated multiple times. Through examining the expression of E(spl)-C genes in honeybees, aphids, and Drosophila, we determined that the complex ancestrally had a role in Notch signaling. The expression patterns of genes found inserted into the complex in some insects, or that of ancestral E(spl)-C genes that have moved out of the complex, imply that the E(spl)-C is a genomic domain regulated as a whole by Notch signaling. We hypothesize that the E(spl)-C is a Notch-regulated genomic domain conserved in Arthropod genomes for around 420 million years. We discuss the consequence of this conserved domain for the recruitment of novel genes into the Notch signaling cascade. PMID:20458100

Duncan, Elizabeth J.; Dearden, Peter K.



Biological function and molecular mechanism of Twist2.  


Twist2, one of the basic helix-loop-helix protein (bHLH) family members, is responsible for the transcriptional regulation in mesenchymal cell lineages during its development. Twist2 functions as a molecular switch to activate or repress target genes by direct or indirect mechanisms. Twist2 can directly bind with conserved E-box on DNA sequence, to recruit co-activators or repressors, and interfere with the activation or inhibition function through protein-protein interactions with E-protein modulators. Nonsense mutations of Twist2 cause Setleis syndrome. Early research on Twist2 focused on osteogenesis, and then expression differences were found in a wide variety of tumors. Further studies showed that Twist2 plays an important role in cancer epithelial-mesenchymal transition (EMT). Regulation function of Twist2 is controlled by temporal and spatial expression, phosphorylation, dimerization and cell positioning adjustment. The involvement of Twist2 in a broad spectrum of regulatory pathways highlights the importance of understanding its role in normal development, homeostasis and disease. In this review, we summarize the role of Twist2 in osteogenesis differentiation, tumor formation and EMT, and its molecular mechanism. It is helpful to have a thorough understanding of the biological functions of Twist2, and facilitate the transformation and application in diagnosis, development and therapy. PMID:25608809

Chengxiao, Zhao; Ze, Yang



Role of AHR, AHRR and ARNT in response to dioxin-like PCBs in Spaurus aurata.  


The aryl hydrocarbon receptor (AHR) mediates a variety of biological responses to ubiquitous dioxin and PCB dioxin-like. AHR together with ARNT, AHRR, represent a novel basic helix-loop-helix/PAS family of transcriptional regulators. Their interplay may affect the xenobiotic response. The aim of this study was to investigate, by histological, immunohistochemical investigations and western-blot analysis, the expression of AHR, ARNT and AHRR in liver of seabrem (Spaurus aurata) after exposure at different time to dioxin-like PCB126 in order to deep the knowledge about their specific role. The findings showed a significant increase of AHR and ARNT expression in juvenile fishes after 12 h than control group. The induction of AHR and ARNT is also significant at 24 and 72 hours compared to the control group. Furthemore, induction of AHRR expression has proved to increase both 12 h but this induction does not seem significant to 24 and 72 hours. The most important data of this work is that the induction of AHRR, when the action of the toxic persistence substances, as dioxin and PCB-126, it is not enough to reduce AHR signaling and thus its hyperactivation leads to toxic effects in seabrem (Spaurus aurata). All this confirms the importance of AHR ligands as new class of drugs that can be directed against severe disease such as cancer. PMID:25060310

Calò, Margherita; Licata, Patrizia; Bitto, Alessandra; Lo Cascio, Patrizia; Interdonato, Monica; Altavilla, Domenica



Myogenin is a positive regulator of MEGF10 expression in skeletal muscle.  


MEGF10 is known to function as a myogenic regulator of satellite cells in skeletal muscle. Mutations in MEGF10 gene cause a congenital myopathy called early onset myopathy, areflexia, respiratory distress and dysphagia (EMARDD). Despite its biological importance in muscle physiology, transcriptional regulation of the MEGF10 gene is unknown. Here, we characterized the 5' flanking region of the human MEGF10 gene and showed that the role of myogenic basic helix-loop-helix factor (bHLH) myogenin in MEGF10 transcription in muscle cells. Myogenin was found to share a similar expression pattern with MEGF10 during muscle regeneration and to increase the promoter activity of the MEGF10 gene in C2C12 cells. Overexpression of myogenin led to upregulation of MEGF10 mRNA in C2C12 cells. Site-directed mutagenesis assays revealed that the conserved E-box element at the region -114/-108 serves as a myogenin-binding motif. Promoter enzyme immunoassays and chromatin immunoprecipitation analysis showed direct interaction between myogenin and the myogenin-binding motif in the MEGF10 promoter. Taken together, these results indicate that myogenin is a positive regulator in transcriptional regulation of MEGF10 in skeletal muscle. PMID:25044114

Park, Seung-Yoon; Yun, Youngeun; Kim, Mi-Jin; Kim, In-San



Conditional deletion of neurogenin-3 using Nkx2.1iCre results in a mouse model for the central control of feeding, activity and obesity  

PubMed Central

SUMMARY The ventral hypothalamus acts to integrate visceral and systemic information to control energy balance. The basic helix-loop-helix transcription factor neurogenin-3 (Ngn3) is required for pancreatic ?-cell development and has been implicated in neuronal development in the hypothalamus. Here, we demonstrate that early embryonic hypothalamic inactivation of Ngn3 (also known as Neurog3) in mice results in rapid post-weaning obesity that is associated with hyperphagia and reduced energy expenditure. This obesity is caused by loss of expression of Pomc in Pomc- and Cart-expressing (Pomc/Cart) neurons in the arcuate nucleus, indicating an incomplete specification of anorexigenic first order neurons. Furthermore, following the onset of obesity, both the arcuate and ventromedial hypothalamic nuclei become insensitive to peripheral leptin treatment. This conditional mouse mutant therefore represents a novel model system for obesity that is associated with hyperphagia and underactivity, and sheds new light upon the roles of Ngn3 in the specification of hypothalamic neurons controlling energy balance. PMID:23649822

Anthwal, Neal; Pelling, Michelle; Claxton, Suzanne; Mellitzer, Georg; Collin, Caitlin; Kessaris, Nicoletta; Richardson, William D.; Gradwohl, Gérard; Ang, Siew-Lan



Delta–Notch—and then? Protein interactions and proposed modes of repression by Hes and Hey bHLH factors  

PubMed Central

Hes and Hey genes are the mammalian counterparts of the Hairy and Enhancer-of-split type of genes in Drosophila and they represent the primary targets of the Delta–Notch signaling pathway. Hairy-related factors control multiple steps of embryonic development and misregulation is associated with various defects. Hes and Hey genes (also called Hesr, Chf, Hrt, Herp or gridlock) encode transcriptional regulators of the basic helix-loop-helix class that mainly act as repressors. The molecular details of how Hes and Hey proteins control transcription are still poorly understood, however. Proposed modes of action include direct binding to N- or E-box DNA sequences of target promoters as well as indirect binding through other sequence-specific transcription factors or sequestration of transcriptional activators. Repression may rely on recruitment of corepressors and induction of histone modifications, or even interference with the general transcriptional machinery. All of these models require extensive protein–protein interactions. Here we review data published on protein–protein and protein–DNA interactions of Hairy-related factors and discuss their implications for transcriptional regulation. In addition, we summarize recent progress on the identification of potential target genes and the analysis of mouse models. PMID:17586813

Fischer, Andreas; Gessler, Manfred



Inhibitor of Differentiation 1 Promotes Endothelial Survival in a Bleomycin Model of Lung Injury in Mice  

PubMed Central

The Id family of genes encodes negative regulators of basic helix-loop-helix transcription factors and has been implicated in diverse cellular processes such as proliferation, apoptosis, differentiation, and migration. However, the specific role of Id1 in lung injury has not been investigated. Bleomycin has been widely used to generate animal models of acute lung injury and fibrogenesis. In this study we found that, on bleomycin challenge, Id1 expression was significantly up-regulated in the lungs, predominantly in endothelial cells, as revealed by double immunolabeling and quantitative flow cytometric analysis. Mice with Id1 loss-of-function (Id1?/?) displayed increased vascular permeability and endothelial apoptosis in the lungs after bleomycin-induced injury. Cultured Id1?/? lung microvascular endothelial cells also showed decreased survival when exposed to bleomycin. We detected a decrease in the level of Bcl-2, a primary anti-apoptotic protein, in Id1?/? endothelial cells, suggesting that down-regulated Bcl-2 may promote endothelial apoptosis in the lung. Therefore, we propose that Id1 plays a crucial role in promoting endothelial survival in the adult lung on injury. In addition, bleomycin-exposed Id1?/? mice showed increased lung collagen accumulation and fibrogenesis, suggesting that Id1 up-regulation in the lung may play a critical role in lung homeostasis. PMID:17717145

Zhang, Huimin; Lawson, William E.; Polosukhin, Vasiliy V.; Pozzi, Ambra; Blackwell, Timothy S.; Litingtung, Ying; Chiang, Chin



Selective down-regulation of tyrosinase family gene TYRP1 by inhibition of the activity of melanocyte transcription factor, MITF  

PubMed Central

Tyrosinase (TYR), tyrosinase-related protein-1 (TYRP1/gp75) and dopachrome tautomerase (DCT/TYRP2) belong to a family of melanocyte-specific gene products involved in melanin pigmentation. During melanocyte development expression of tyrosinase family genes is thought to be orchestrated in part by the binding of a shared basic helix–loop–helix transcription factor MITF to the M box, a regulatory element conserved among these genes. In transformed melanocytes, expression of tyrosinase and TYRPs is highly variable. Whereas TYR expression in melanoma cells is regulated by both transcriptional and post-translational mechanisms, TYRP1/gp75 transcription is often completely extinguished during melanoma tumor progression. In this study, we investigated the mechanisms of selective repression of TYRP1 transcription. Interestingly, in early stage melanoma cells TYRP1 mRNA could be induced by inhibition of protein synthesis. Transient transfection experiments with a minimal TYRP1 promoter showed that the promoter activity correlates with expression of the endogenous TYRP1 gene. Nucleotide deletion analysis revealed novel regulatory sequences that attenuate the M box-dependent MITF activity, but which are not involved in the repression of TYRP1. Gel mobility shift analysis showed that binding of the transcription factor MITF to the TYRP1 M box is selectively inhibited in TYRP1– cells. These data suggest that protein factors that modulate the activity of MITF in melanoma cells repress TYRP1 and presumably other MITF target genes. PMID:12136092

Fang, Dong; Tsuji, Yoshiaki; Setaluri, Vijayasaradhi



Basic properties and variability  

NASA Technical Reports Server (NTRS)

Giant and supergiant M, S, and C stars are discussed in this survey of research. Basic properties as determined by spectra, chemical composition, photometry, or variability type are discussed. Space motions and space distributions of cool giants are described. Distribution of these stars in our galaxy and those nearby is discussed. Mira variables in particular are surveyed with emphasis on the following topics: (1) phase lag phenomenon; (2) Mira light curves; (3) variations in color indices; (4) determination of multiple periods; (5) correlations between quantities such as period length, light-curve shape, infrared (IR) excess, and visible and IR color diagram; (6) semiregular (SR) variables and different time scales in SR light variations; (7) irregular variable Lb and Lc stars; (8) different time-scale light variations; (9) hydrogen-deficient carbon (HdC) stars, in particular RCB stars; and (10) irreversible changes and rapid evolution in red variable stars.

Querci, Francois R.



Basics of AC Drives  

NSDL National Science Digital Library

This course is one of the quickStep series offered by Siemens in AC Drives. These are FREE on-line industrial knowledge building tutorials. quickSTEPs are a great start for industry novices moving into technical jobs or staff in operational support rolls. They can also be very effectively used as out of class assignments for review or to build fundamental skills. Each course includes: an online tutorial organized as a number of units, lessons with self check quiz questions, a glossary of terms, a self-check final exam with scoring, an extensive downloadable PDF study guide. This course covers AC motor basics, details of the Siemens masterdrive and micromaster, and detailed application notes on torque and horsepower.


Basics of Electricity  

NSDL National Science Digital Library

This course is one of the quickStep series offered by Siemens in Electricity. These are FREE on-line industrial knowledge building tutorials. quickSTEPs are a great start for industry novices moving into technical jobs or staff in operational support rolls. They can also be very effectively used as out of class assignments for review or to build fundamental skills. Each course includes: an online tutorial organized as a number of units, lessons with self check quiz questions, a glossary of terms, a self-check final exam with scoring, an extensive downloadable PDF, and a study guide. This course focuses on the basics of electricity. The coverage includes: DC circuits, magnetism, alternating current, reactance, impedance, AC circuits and an 88 page study guide.


Basic Accounting Lesson Plans  

NSDL National Science Digital Library

Are balance sheets, income statements and cash flow statements keeping you up at night? Well, beginning accounting students (or others with an interest in such matters) will appreciate these basic accounting lesson plans, provided courtesy of the website. The first section contains a number of lesson plans and worksheets that include topics such as the fundamental concepts of accounting, transaction analysis, accrual accounting and adjusting entries. Moving on, the site also contains a number of useful articles on various topics within the field, such as bookkeeping, ledgers, and profit and loss reports. The site is rounded out by a selection of helpful accounting textbooks that students may wish to look for as they continue their journey through the world of accounting.


Basic and Clinical Neurosciences  

NSDL National Science Digital Library

Columbia University's College of Physicians and Surgeons has been a leader in medical education for over a century, and this website is provided as public service for those in the field of medicine and neuroscience. The website provides a series of lectures and videos that provide a "comprehensive and concise review of the neurosciences." It's best to start by reading the executive summary, and then click on over to the "Topics and Speakers" area. Here visitors can look over several dozen lectures that include "Basic Mechanisms of Pain", "Molecular Genetics", and "Neurobiology of Schizophrenia". The lectures are all of very high quality, and visitors who are seeking additional information should look through the "References and Resources" area for external links to relevant medical organizations, research institutes, and academic departments.


Fluid Power Basics  

NSDL National Science Digital Library

Students learn about the fundamental concepts important to fluid power, which includes both pneumatic (gas) and hydraulic (liquid) systems. Both systems contain four basic components: reservoir/receiver, pump/compressor, valve, cylinder. Students learn background information about fluid power—both pneumatic and hydraulic systems—including everyday applications in our world (bulldozers, front-end loaders, excavators, chair height lever adjustors, door closer dampers, dental drills, vehicle brakes) and related natural laws. After a few simple teacher demos, they learn about the four components in all fluid power systems, watch two 26-minute online videos about fluid power, complete a crossword puzzle of fluid power terms, and conduct a task card exercise. This prepares them to conduct the associated hands-on activity, using the Portable Fluid Power Demonstrator (teacher-prepared kits) to learn more about the properties of gases and liquids in addition to how forces are transmitted and multiplied within these systems.



Basic memory module  

NASA Technical Reports Server (NTRS)

Construction and electrical characterization of the 4096 x 2-bit Basic Memory Module (BMM) are reported for the Space Ultrareliable Modular Computer (SUMC) program. The module uses four 2K x 1-bit N-channel FET, random access memory chips, called array chips, and two sense amplifier chips, mounted and interconnected on a ceramic substrate. Four 5% tolerance power supplies are required. At the Module, the address, chip select, and array select lines require a 0-8.5 V MOS signal level. The data output, read-strobe, and write-enable lines operate at TTl levels. Although the module is organized as 4096 x 2 bits, it can be used in a 8196 x 1-bit application with appropriate external connections. A 4096 x 1-bit organization can be obtained by depopulating chips.

Tietze, F. C.



Chronic Pancreatitis (Beyond the Basics)  


... Irritable bowel syndrome (Beyond the Basics) Patient information: Pancreatic cancer (Beyond the Basics) Clinical manifestations and diagnosis of ... of the upper intestine ? An increased risk of pancreatic cancer PANCREATITIS DIAGNOSIS It can be difficult to diagnose ...


Basics (Long-Term Care)  


... the care you may need. Share page: The Basics In the 2000, almost 10 million people needed ... their lives. This section of the website provides basic information so you can begin to think about ...


Basic logic: reflection, symmetry, visibility.  

E-print Network

Basic logic: reflection, symmetry, visibility. Giovanni Sambin - Giulia Battilotti - Claudia Faggian Abstract We introduce a sequent calculus B for a new logic, named basic logic. The aim of basic logic is to find a structure in the space of logics. Classical, intuitionistic, quantum and non

Sambin, Giovanni


Basic Usage of Signal Generator Basic Usage of Oscilloscope  

E-print Network

Topics: Basic Usage of Signal Generator Basic Usage of Oscilloscope Capacitor Required Equipment and Components: CRO (Cathode Ray Oscilloscope) Breadboard DC power supply Resistors Function Generator Capacitor Information: Signal Generators A signal generator is an electronic instrument that generates repeating voltage

Ã?nay, Devrim


Assessment of Basic Social Skills  

Microsoft Academic Search

Following recent developments in the measurement of individual differences in nonverbal social skills, we proposed a conceptual framework for defining and assessing basic social skills. Preliminary testing resulted in the development of a 105-item, pencil-and-paper measure of seven basic dimensions of social skills, called the Social Skills Inventory (SSI). In a series of validation studies using undergraduate students, the SSI

Ronald E. Riggio



Basic Writing as Cultural Conflict.  

ERIC Educational Resources Information Center

Describes the deficit theories and skills approaches shaping how teachers, administrators, and students conceive of basic writers. Critiques research on cultural conflict in the classroom and the theory that students must be initiated into academic discourse. Explores John Ogbu's "oppositional culture" theory to better understand basic writers…

Fox, Tom



Basic local alignment search tool  

Microsoft Academic Search

A new approach to rapid sequence comparison, basic local alignment search tool (BLAST),directly approsimates alignments that optimize a measure of local similarity, the maximal segment pair (3ISP) score. Recent mathematical results on the stochastic properties of MSP scores allow an anallrsis of the performance of this method as well as the statistical significance of alignments it generates. The basic algorithm

Stephen F. Altschul; Warren Gish; Webb C. Miller; Eugene W. Myers; David J. Lipman



Basics Truth Tables of Operators  

E-print Network

1 Logic #12;2 Outline · Basics · Truth Tables of Operators · Logic Formulae ­Evalua:on; Truth Tables · Equivalence ­Laws; Proving · Inferences CSE 215: Logic #12. E.g., · ~p · ~(p V ~q) CSE 215: Logic #12;6 Outline · Basics · Truth

Gupta, Himanshu


Children and Their Basic Needs.  

ERIC Educational Resources Information Center

Describes obstacles presented by poverty in the fulfillment of the basic needs of children. Individually addresses Maslow's five basic needs with regard to children reared in poverty: (1) physiological needs; (2) safety needs; (3) belonging and love needs; (4) self-esteem needs; and (5) self-actualization needs. (Author/SD)

Prince, Debra Lindsey; Howard, Esther M.




EPA Science Inventory

Abstract Inhibitor of DNA binding (Id2) is a member of the helix-loop-helix (HLH) transcription factor family whose members play important roles in cell differentiation and proliferation. Id2 has been linked to the development of cardiovascular diseases since thiazolidinediones,...


Vector Geometry Mapping 1 Job: Vogel 2 689-8 (MiMB) Operator: Sean Murdock  

E-print Network

Vector Geometry Mapping 1 Job: Vogel 2 689-8 (MiMB) Operator: Sean Murdock Chapter: 24 (Yap et al 24 Vector Geometry Mapping: A Method to Characterize the Conformation of Helix-Loop-Helix Calcium of parameters to be interpreted by the user. In this chapter, we describe a method termed Vector Geometry

Ikura, Mitsuhiko


Characterisation and therapeutic modulation of toll-like receptor signalling in response to the intracellular pathogen F. tularensis  

E-print Network

containing vacuole FimH Fimbriae H protein FPI Francisella pathogenicity island GSK3B Glycogen synthase kinase-3B HDAC Histone deacetylase HLH Helix-loop-helix HMGB-1 High-mobility group box-1 HRP Horseradish peroxidase HSV Herpes simplex virus IFN...

Saint, Richard



A. Transcription Factors: 1. Classes of transcription factors  

E-print Network

the 4. Helix-loop-helix proteins - Common motifs - The loop region is b. bHLH proteins = · Presence of · Ability a. HLH proteins contain 2 i. One face is ii. Other face #12;14 - bHLH proteins i. Class A = ii

Andres, Andrew


1605 The Journal of Experimental Medicine Volume 190, Number 11, December 6, 1999 16051616  

E-print Network

remain largely unknown. Previous studies have shown that the helix- loop-helix (HLH) proteins, E12 and E by one gene, designated E2A, and arise through alternative splicing of the exon encoding the HLH domain as a complex with HeLa E-box binding protein (HEB), another HLH protein which is expressed at particularly high

Hedrick, Stephen M.


Basic Blood Tests (For Parents)  


... the basic blood chemistry test include blood urea nitrogen and creatinine, which tell how well the kidneys ... amount of sugar in the blood. Blood urea nitrogen (BUN) is a measure of how well the ...


Basic HIV/AIDS Statistics  


... Syndicated Content Podcasts Slide Sets HIV/AIDS Basic Statistics Language: English Español (Spanish) Share Compartir  HIV ... impact. Interested in learning more about CDC's HIV statistics? Terms, definitions, and calculations that CDC uses in ...


Basic Hydrologic Sciences Course Orientation  

NSDL National Science Digital Library

This brief presentation provides an overview of the COMET Basic Hydrologic Sciences course including: goal and target audiences, structure of the course and adapting it to your needs, and a brief description of course components.



Basic Communication Course Annual. Volume 5.  

ERIC Educational Resources Information Center

This volume of an annual collection of essays relating to instruction in the basic communication course presents 1992 Speech Communication Association Basic Course Committee award winning papers, articles on teaching assistants in the basic course, approaches to teaching in the basic course, research on the basic course, and a commentary. Essays…

Hugenberg, Lawrence W., Ed.


Smoothed Particle Hydrodynamics Code Basics  

NASA Astrophysics Data System (ADS)

SPH is the shorthand for Smoothed Particle Hydrodynamics. This method is a Lagrangian method which means that it involves following the motion of elements of fluid. These elements have the characteristics of particles and the method is called a particle method. A useful review of SPH (Monaghan 1992) gives the basic technique and how it can be applied to numerous problems relevant to astrophysics. You can get some basic SPH programs from In the present lecture I will assume that the student has studied this review and therefore understands the basic principles. In today's lecture I plan to approach the equations from a different perspective by using a variational principle.

Monaghan, J. J.



Basic Operational Robotics Instructional System  

NASA Technical Reports Server (NTRS)

The Basic Operational Robotics Instructional System (BORIS) is a six-degree-of-freedom rotational robotic manipulator system simulation used for training of fundamental robotics concepts, with in-line shoulder, offset elbow, and offset wrist. BORIS is used to provide generic robotics training to aerospace professionals including flight crews, flight controllers, and robotics instructors. It uses forward kinematic and inverse kinematic algorithms to simulate joint and end-effector motion, combined with a multibody dynamics model, moving-object contact model, and X-Windows based graphical user interfaces, coordinated in the Trick Simulation modeling environment. The motivation for development of BORIS was the need for a generic system for basic robotics training. Before BORIS, introductory robotics training was done with either the SRMS (Shuttle Remote Manipulator System) or SSRMS (Space Station Remote Manipulator System) simulations. The unique construction of each of these systems required some specialized training that distracted students from the ideas and goals of the basic robotics instruction.

Todd, Brian Keith; Fischer, James; Falgout, Jane; Schweers, John



Adult Basic Education: Aligning Adult Basic Education and Postsecondary Education  

ERIC Educational Resources Information Center

In 2007, the 80th Texas Legislature included a rider to the General Appropriations Act for the Texas Higher Education Coordinating Board. The rider directed the agency to coordinate with the Texas Education Agency to develop and implement plans to align adult basic education with postsecondary education. The Coordinating Board, in collaboration…

Texas Higher Education Coordinating Board, 2008



Arabic Basic Course: Basic Dialogues for Airport Facilities.  

ERIC Educational Resources Information Center

This booklet is intended for use as supplementary material in the Advanced Phase of the "Arabic Basic Course," developed and implemented at the Defense Language Institute. The purpose of this book is to acquaint students with specialized airport terminology pertaining to takeoff and landing procedures directed in modern, standard Arabic. The…

Defense Language Inst., Washington, DC.


Cosmic Particle Acceleration: Basic Issues  

E-print Network

Cosmic-rays are ubiquitous, but their origins are surprisingly difficult to understand. A review is presented of some of the basic issues common to cosmic particle accelerators and arguments leading to the likely importance of diffusive shock acceleration as a general explanation. The basic theory of diffusive shock acceleration is outlined, followed by a discussion of some of the key issues that still prevent us from a full understanding of its outcomes. Some recent insights are mentioned at the end that may help direct ultimate resolution of our uncertainties.

T. W. Jones



32 CFR 761.7 - Basic controls.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Basic controls. 761.7 Section...PACIFIC ISLANDS Criteria and Basic Controls § 761.7 Basic controls. (a) General...person, except persons aboard public vessels or aircraft of the...



Adult Basic Education; Operations Manual.  

ERIC Educational Resources Information Center

This publication is an administrative guide for Missouri school administrators and local adult basic education supervisors. First, general information is given as to legislative authority, standards for approval, procedures for implementation, expenditures and reimbursement, teacher qualifications, program administration, student eligibility and…

Missouri State Dept. of Education, Jefferson City.


The Basics of Design Engineering  

NSDL National Science Digital Library

A product of Penton Publishing, The Basics of Design Engineering is a wonderful introduction to this field of engineering. The site is divided into eight chapters--Motion Control, CAD/CAM, Materials, Mechanical Systems and Components, Fluid Power, Electrical and Electronic, Fastening and Joining, and Training/Outsourcing. Each chapter is further broken into multiple sections, making information easy to access.



Monte Carlo Basics 1 Introduction  

E-print Network

1 Monte Carlo Basics §1 Introduction WHAT IS THE MONTE CARLO METHOD? · Monte Carlo (MC) method. Multidimensional integrations (e.g., statistical mechanics in physics); 2. Simulation of stochastic natural phenomena (e.g., stock price). · Numerical vs. MC Integration The simplest numerical integration of a one

Southern California, University of



E-print Network

PHOSPHORUS BASICS Larry G. Bundy Dept. of Soil Science University of Wisconsin #12;Phosphorus Terminology · Phosphorus (P) = element name and symbol · P2O5 = phosphate (oxide) Amount of P in fertilizers use #12;Forms & Concentrations of Phosphorus (P) in Soils Form Concentration (ppm) Total 1000 Soil

Balser, Teri C.


Building a Basic Series Circuit  

NSDL National Science Digital Library

This activity was designed for blind learners, but all types of learners can use it to build and examine a basic electrical circuit. Other activities using the circuit set-up are outlined, such as making an electric fan. A safety note cautions that goggles should be worn at all times when using electricity.

Perkins School for the Blind




SciTech Connect

A brief review of the theory of generalized parton distributions (GPDs) is given. We discuss the basic concepts of the GPD theory and relationship between GPDs and simpler phenomenological functions, viz. form factors, parton densities and distribution amplitudes. A special emphasis is given to the formulation of GPDs in terms of double distributions.

Anatoly Radyushkin



JSC interactive basic accounting system  

NASA Technical Reports Server (NTRS)

Design concepts for an interactive basic accounting system (IBAS) are considered in terms of selecting the design option which provides the best response at the lowest cost. Modeling the IBAS workload and applying this workload to a U1108 EXEC 8 based system using both a simulation model and the real system is discussed.

Spitzer, J. F.



The Future of Basic Writing  

ERIC Educational Resources Information Center

In this article, we assess the status of basic writing early in the twenty-first century. Beginning with a discussion of the attacks on BW that intensified during the 1990s and early 2000s--attacks that originated from such diverse sources as state legislatures, university officials, and BW scholars themselves--we go on to summarize the responses…

Otte, George; Mlynarczyk, Rebecca Williams



Masonry. Basic Course. Career Education.  

ERIC Educational Resources Information Center

Several intermediate performance objectives and corresponding criterion measures are listed for each of 22 terminal objectives for a basic masonry course. The materials were developed for a 36-week course (2 hours daily). Organized subject matter and practical experiences are designed to prepare students for entry level skills in the masonry…

Muldrow, Oliver



ERIC Educational Resources Information Center




Adult Basic Education Pilot Project.  

ERIC Educational Resources Information Center

The adult basic education program of the Texas Extension Division of Texas University was organized to provide educational opportunities for at least 200 undereducated adults, evaluate materials and teaching techniques in actual classroom use, develop a student record and progress chart for reporting and evaluation in local projects, explore…

Texas Univ., Austin. Extension Teaching and Field Service Bureau.


Basic Telecommunications, The Physical Layer  

NSDL National Science Digital Library

This page from Delmar Learning provides more information about the book "Basic Telecommunications, The Physical Layer" by Gary J. Mullet. The book includes information on wireline, wireless, and other fiber optic topics, focusing on physical layer implementation of system hardware. Users may order the book via this website. A link is also provided to request a review copy.

Mullett, Gary J.



Drafting. Performance Objectives. Basic Course.  

ERIC Educational Resources Information Center

Several intermediate performance objectives and corresponding criterion measures are listed for each of 12 terminal objectives for a basic drafting course. The materials were developed for a two-semester course (2 hours daily). The organized classroom and shop experiences are designed to enable the student to develop general competencies in the…

Allen, Charles


Harmonic Morphisms -Basics Sigmundur Gudmundsson  

E-print Network

Harmonic Morphisms - Basics Sigmundur Gudmundsson Department of Mathematics Faculty of Science Lund University March 11, 2014 #12;Harmonic Maps in Gaussian Geometry Harmonic Maps in Riemannian Geometry Outline 1 Harmonic Maps in Gaussian Geometry Holomorphic Functions in One

Gudmundsson, Sigmundur


Dynamic Meteorology - A Basic Course  

NASA Astrophysics Data System (ADS)

Dynamic Meteorology is an introduction to the physics of the atmosphere. Starting from the basics, it provides students with an awareness of simple mathematics and enthusiastically proceeds to provide a thorough grounding in the fundamentals of meteorology. The authors lead students to a scientifically rigorous understanding of the behavior of weather systems such as highs, lows, fronts, jet streams, and tropical cyclones.

Gordon, Adrian; Grace, Warwick; Schwerdtfeger, Peter; Byron-Scott, Roland



(Introductory Version) Basic Training Course  

E-print Network

to plants in Virginia, such as invasive species. 8. Recognize some common plants occurring in the local Course Objectives 1. Describe the diversity and distribution of plants in Virginia. 2. Describe the role of plants in Virginia's ecosystems. 3. Describe the natural history and basic biology of plants. 4. Describe

Liskiewicz, Maciej


French Basic Course. Area Studies.  

ERIC Educational Resources Information Center

This volume provides the prescribed cultural background that is part of the final phase of the Basic Course in French. The texts provide the basis for discussions and personal research through which students become acquainted with various aspects of the French-speaking world and learn the referential meaning of words and expressions as they are…

Defense Language Inst., Monterey, CA.


Basic Tax Rules for Distributions  

NSDL National Science Digital Library

The legal and financial publisher Nolo Press provides this chapter entitled "Basic Tax Rules from Distributions" from their new retirement planning book IRAs, 401(k)s & Other Retirement Plans: Taking Your Money Out. The chapter covers the fundamental tax rules applicable to retirement plans, with specific attention to planning, special income tax rules, and tax rules for IRAs.


Keep Communication Professional BASIC TIPS  

E-print Network

and be sure to represent the company well when interacting with clients. In written communicationsKeep Communication Professional BASIC TIPS: Staying professional in your career is vital. You the way through your career until you retire. It's important to not become too casual when communicating

Gering, Jon C.


Carpentry. Performance Objectives. Basic Course.  

ERIC Educational Resources Information Center

Several intermediate performance objectives and corresponding criterion measures are listed for each of 12 terminal objectives in this course guide in basic carpentry. The guide is designed to prepare persons for initial employment, or to upgrade or retrain persons already employed, or to provide the apprenticeship related course work necessary to…

Downing, C. L.; Adcox, John W., Jr.


Basic Skills for the Workplace.  

ERIC Educational Resources Information Center

This book is a practitioner's guide to developing literacy training programs for workers. Titles of the 28 chapters and epilogue are as follows: "Understanding the History and Definitions of Workplace Literacy" (Askov, Aderman); "Understanding Literacy in the Canadian Business Context: Conference Board of Canada Study" (Hart); "Understanding Basic

Taylor, Maurice C., Ed.; And Others


Environmental Education: Back to Basics.  

ERIC Educational Resources Information Center

Describes an instructional framework based on concepts of energy, ecosystems, carrying capacity, change, and stewardship. Stresses the importance of determining what is really important (basic) for each student to experience or learn in relation to each concept and grade level. Student-centered learning activities and sample lesson on energy…

Warpinski, Robert



Negativity bias and basic values.  


Basic values explain more variance in political attitudes and preferences than other personality and sociodemographic variables. The values most relevant to the political domain are those likely to reflect the degree of negativity bias. Value conflicts that represent negativity bias clarify differences between what worries conservatives and liberals and suggest that relations between ideology and negativity bias are linear. PMID:24970450

Schwartz, Shalom H



Basic Mechanisms of the Epilepsies.  

ERIC Educational Resources Information Center

A collection of highly technical scientific articles by international basic and clinical neuroscientists constitutes a review of their knowledge of the brain and nervous system, particularly the aspects related to loss of brain function control and its explosive discharges which cause epileptic seizures. Anatomy, biophysics, biochemistry, and…

Jasper, Herbert H., Ed.; And Others


Basic Mathematics Machine Calculator Course.  

ERIC Educational Resources Information Center

This series of four text-workbooks was designed for tenth grade mathematics students who have exhibited lack of problem-solving skills. Electric desk calculators are to be used with the text. In the first five chapters of the series, students learn how to use the machine while reviewing basic operations with whole numbers, decimals, fractions, and…

Windsor Public Schools, CT.


Basic Applied Mathematics Part 1.  

ERIC Educational Resources Information Center

This guide, published by the New York City Board of Education, presents 62 lesson plans in basic mathematics for tenth grade students. Lesson plans and performance objectives focus on the following areas: (1) fundamental operations with signed numbers; (2) linear, weight and temperature measurements; (3) fractions, decimals and percents; (4)…

New York City Board of Education, Brooklyn, NY. Div. of Curriculum and Instruction.


Welding. Performance Objectives. Basic Course.  

ERIC Educational Resources Information Center

Several intermediate performance objectives and corresponding criterion measures are listed for each of eight terminal objectives for a basic welding course. The materials were developed for a 36-week (2 hours daily) course developed to teach the fundamentals of welding shop work, to become familiar with the operation of the welding shop…

Vincent, Kenneth


Federal Grants: A Basic Handbook.  

ERIC Educational Resources Information Center

Presented are some basic facts about the process of getting federal money for individual research projects, institutional activities, curriculum development, or other programs in higher education institutions. Some background is given on the purposes and history of federal grant monies, and steps in the proposal process are outlined: gathering…

Mohrman, Kathryn; And Others


Re-Modeling Basic Writing  

ERIC Educational Resources Information Center

In 1996, the State University of New York at New Paltz developed the Supplemental Writing Workshop Program for its basic writing students in response to public pressure to discontinue the offering of so-called remedial writing courses at four-year institutions. Our primary purpose in this article is to describe the design of the SWW Program, which…

Rigolino, Rachel; Freel, Penny



Transient Ischemic Attack (Beyond the Basics)  


... smoking (Beyond the Basics)" ) ? Treating high cholesterol and lipids (see "Patient information: High cholesterol and lipids (hyperlipidemia) (Beyond the Basics)" ) Antiplatelet therapy — Platelets are ...


The Basics of Brain Development  

PubMed Central

Over the past several decades, significant advances have been made in our understanding of the basic stages and mechanisms of mammalian brain development. Studies elucidating the neurobiology of brain development span the levels of neural organization from the macroanatomic, to the cellular, to the molecular. Together this large body of work provides a picture of brain development as the product of a complex series of dynamic and adaptive processes operating within a highly constrained, genetically organized but constantly changing context. The view of brain development that has emerged from the developmental neurobiology literature presents both challenges and opportunities to psychologists seeking to understand the fundamental processes that underlie social and cognitive development, and the neural systems that mediate them. This chapter is intended to provide an overview of some very basic principles of brain development, drawn from contemporary developmental neurobiology, that may be of use to investigators from a wide range of disciplines. PMID:21042938

Stiles, Joan



Basic Science and The NIH  

PubMed Central

The following is an edited version of the Keynote Speech delivered at the Annual Meeting of the American Society for Cell Biology by Harold Varmus, Director of the National Institutes of Health. The address, entitled Basic Science and the NIH, was given at the opening of the meeting in New Orleans on December 11, 1993. It was Varmus' first public policy talk as NIH Director. PMID:8049519

Varmus, Harold



Basic Concepts of Optical Microscopy  

NSDL National Science Digital Library

This site is a comprehensive primer focused on the basic optical microscope, as well as the electron, confocal, polarizing, and stereoscopic microscopes. Virtual microscopes allow the user to simulate the use of a variety of real-life microscopes. There are galleries of photomicrographs illustrating a variety of specimens. This website provides complete instructional materials on the theory of light and the applications of microscopy to a variety of analytical problems.

Davidson, Michael W.



Remote Sensing Guides: Basic Concepts  

NSDL National Science Digital Library

The Remote Sensing guides are designed for people who want to learn how to benefit from remotely sensed imagery without having to learn the nitty-gritty details of how remote sensing works. All guides can be viewed online or downloaded in PDF format. The guides in the Basic Concepts set explain and illustrate fundamental concepts of remote sensing. The set includes these titles: Understanding pixels, bands, and channels, Understanding image scale and resolution and Myths and misconceptions about remote sensing.


Basic Mathematical Concepts and Methods  

Microsoft Academic Search

\\u000a This chapter and the next two have three objectives. First, to introduce the reader to some basic concepts and formulas that\\u000a will be needed in later chapters. Second, to serve as an introduction to computation and numerical methods and the use of\\u000a Excel and Matlab procedures. The present chapter is devoted to mathematics and Chap. 3 is an introduction to

Kamran Dadkhah



NASA Technical Reports Server (NTRS)

The Basic Linear Algebra Subprogram (BLAS) library is a collection of FORTRAN callable routines for employing standard techniques in performing the basic operations of numerical linear algebra. The BLAS library was developed to provide a portable and efficient source of basic operations for designers of programs involving linear algebraic computations. The subprograms available in the library cover the operations of dot product, multiplication of a scalar and a vector, vector plus a scalar times a vector, Givens transformation, modified Givens transformation, copy, swap, Euclidean norm, sum of magnitudes, and location of the largest magnitude element. Since these subprograms are to be used in an ANSI FORTRAN context, the cases of single precision, double precision, and complex data are provided for. All of the subprograms have been thoroughly tested and produce consistent results even when transported from machine to machine. BLAS contains Assembler versions and FORTRAN test code for any of the following compilers: Lahey F77L, Microsoft FORTRAN, or IBM Professional FORTRAN. It requires the Microsoft Macro Assembler and a math co-processor. The PC implementation allows individual arrays of over 64K. The BLAS library was developed in 1979. The PC version was made available in 1986 and updated in 1988.

Krogh, F. T.



Basic Color Terms in Estonian Sign Language  

ERIC Educational Resources Information Center

The article is written in the tradition of Brent Berlin and Paul Kay's theory of basic color terms. According to this theory there is a universal inventory of eleven basic color categories from which the basic color terms of any given language are always drawn. The number of basic color terms varies from 2 to 11 and in a language having a fully…

Hollman, Liivi; Sutrop, Urmas




PubMed Central

There has been a significant amount of research done on liposomes and nanoparticles as drug carriers for protein drugs. Proteins and enzymes have been used both as targeting moieties and for their therapeutic potential. High specificity and rapid reaction rates make proteins and enzymes excellent candidates for therapeutic treatment, but some limitations exist. Many of these limitations can be addressed by a well studied nanotechnology based delivery system. Such a system can provide a medium for delivery, stabilization of the drugs, and enable site specific accumulation of drugs. Nanomedicines such as these have great potential to revolutionize the pharmaceutical industry and improve healthcare worldwide. PMID:25414730

Barry, John N.; Vertegel, Alexey A.



History of coat protein-mediated protection.  


A decade of research has proven that plants can be genetically engineered to resist virus infection through expression of viral CP genes, as well as other viral genes and sequences. Additional opportunities for development of resistant plants will require research focused on mechanisms of protection, improvements in expression vector design, and transformation of new crop species. As each of these technologies is utilized singly or in combination to generate resistant crop varieties, the full impact of such engineered resistance will be realized. PMID:9760491

Miller, E D; Hemenway, C



A basic trilobite morphometric exercise  

NSDL National Science Digital Library

This activity entails a basic morphometrics lab, followed up by an in-class exercise to reinforce some of the same key concepts. The lab exercise familiarizes the student with basic methods of quantitative characterization and statistical comparison through measurement of pygidia (tails) of two species of the Ordovician trilobite Bellefontia â one from New York and one from Pennsylvania. Actual specimens, while nice, are not required; data acquired by measurement from photo collages will suffice. The exercise culminates in a statistical test of significance (using the Z-statistic) of the difference in slopes of the lines acquired for data from the two species. The data also serve to pose questions and prompt consideration of growth trajectories and discrimination of isometric from anisometric growth. The in-class activity builds on the knowledge base built in the lab but applies it to species discrimination based on the cranidia (central part of the head) of three species of the Upper Cambrian genus Bartonaspis, known to be of identical age from their occurrences within the very thin (everywhere 2m or less) Irvingella major Zone of the Elvinia trilobite Zone. The importance of that subzone, which is the "critical interval" at the top of the Pterocephaliid Biomere the basal unit of the Sunwaptan Stage traceable throughout Laurentian North America, also contributes to the significance of the exercise. With the insight developed from the lab, students are able to confidently distinguish the three species of Bartonaspis (from three photo collages), but must thoughtfully evaluate the data presented in bivariate plots of cranidial morphologic data to do so. The exercise gives the students a good sense of the level of familiarity and morphologic characterization necessary to do species-level identification, and also some worthwhile practice in basic quantitative methods.

John Taylor


Virtual Microscope: Light Microscopy Basics  

NSDL National Science Digital Library

This animated tutorial illustrates the basics of light microscopy. It opens with a brief introduction to light refraction and interference. Next, the tutorial explores light microscope anatomy and contrast methods -- including stain, darkfield, and polarized contrast. Finally, it discusses the field of fluorescent light microscopy. This resource is part of the Virtual Microscope project, which provides cost-free simulated scientific instrumentation for students and researchers worldwide as part of NASA's Virtual Laboratory initiative. See Related Materials for links to additional animated tutorials on Atomic Force Microscopy and Scanning Electron Microscopy.



E47 and Id1 Interplay in Epithelial-Mesenchymal Transition  

PubMed Central

E12/E47 proteins (encoded by E2A gene) are members of the class I basic helix-loop-helix (bHLH) transcription factors (also known as E proteins). E47 has been described as repressor of E-cadherin and inducer of epithelial-mesenchymal transition (EMT). We reported previously that EMT mediated by E47 in MDCK cells occurs with a concomitant overexpression of Id1 and Id3 proteins. Id proteins belong to class V of HLH factors that lack the basic domain; they dimerise with E proteins and prevent their DNA interaction, thus, acting as dominant negative of E proteins. Here, we show that E47 interacts with Id1 in E47 overexpressing MDCK cells that underwent a full EMT as well as in mesenchymal breast carcinoma and melanoma cell lines. By conducting chromatin immunoprecipitation assays we demonstrate that E47 binds directly to the endogenous E-cadherin promoter of mesenchymal MDCK-E47 cells in a complex devoid of Id1. Importantly, our data suggest that both E47 and Id1 are required to maintain the mesenchymal phenotype of MDCK-E47 cells. These data support the collaboration between E47 and Id1 in the maintenance of EMT by mechanisms independent of the dominant negative action of Id1 on E47 binding to E-cadherin promoter. Finally, the analysis of several N0 breast tumour series indicates that the expression of E47 and ID1 is significantly associated with the basal-like phenotype supporting the biological significance of the present findings. PMID:23555842

Cubillo, Eva; Moreno-Bueno, Gema; Peinado, Hector; Montes, Amalia; Santos, Vanesa; Portillo, Francisco; Cano, Amparo



mSin3A Regulates Murine Erythroleukemia Cell Differentiation through Association with the TAL1 (or SCL) Transcription Factor  

PubMed Central

Activation of the TAL1 (or SCL) gene is the most frequent gain-of-function mutation in T-cell acute lymphoblastic leukemia (T-ALL). TAL1 belongs to the basic helix-loop-helix (HLH) family of transcription factors that bind as heterodimers with the E2A and HEB/HTF4 gene products to a nucleotide sequence motif termed the E-box. Reported to act both as an activator and as a repressor of transcription, the mechanisms underlying TAL1-regulated gene expression are poorly understood. We report here that the corepressor mSin3A is associated with TAL1 in murine erythroleukemia (MEL) and human T-ALL cells. Interaction mapping showed that the basic-HLH domain of TAL1 was both necessary and sufficient for TAL1-mSin3A interaction. TAL1 was found, in addition, to interact with the histone deacetylase HDAC1 in vitro and in vivo, and a specific histone deacetylase inhibitor, trichostatin A (TSA), relieved TAL1-mediated repression of an E-box-containing promoter and a GAL4 reporter linked to a thymidine kinase minimal promoter. Further, TAL1 association with mSin3A and HDAC1 declined during dimethyl sulfoxide-induced differentiation of MEL cells in parallel with a decrease in mSin3A abundance. Finally, TSA had a synergistic effect with enforced TAL1 expression in stimulating MEL cells to differentiate, while constitutive expression of mSin3A inhibited MEL cell differentiation. These results demonstrate that a corepressor complex containing mSin3A and HDAC1 interacts with TAL1 and restricts its function in erythroid differentiation. This also has implications for this transcription factor's actions in leukemogenesis. PMID:10688671

Huang, Suming; Brandt, Stephen J.



Gaia basic angle monitoring system  

NASA Astrophysics Data System (ADS)

The Gaia mission will create an extraordinarily precise three-dimensional map of more than one billion stars in our Galaxy. The Gaia spacecraft, built by EADS Astrium, is part of ESA's Cosmic Vision programme and scheduled for launch in 2013. Gaia measures the position, distance and motion of stars with an accuracy of 24 micro-arcsec using two telescopes at a fixed mutual angle of 106.5°, named the ‘Basic Angle’. This accuracy requires ultra-high stability, which can only be achieved by using Silicon Carbide for both the optical bench and the telescopes. TNO has developed, built and space qualified the Silicon carbide Basic Angle Monitoring (BAM) on-board metrology system for this mission. The BAM measures the relative motion of Gaia’s telescopes with accuracies in the range of 0.5 micro-arcsec. This is achieved by a system of two laser interferometers able to measure Optical Path Differences (OPD) as small as 1.5 picometer rms. Following a general introduction to the Gaia mission, the Payload Module (PLM) and the use of Silicon Carbide as base material, this presentation will address an overview of the challenges towards the key requirements, design, integration and testing (including space-level qualification) of the Gaia BAM.

Gielesen, W.; de Bruijn, D.; van den Dool, T.; Kamphues, F.; Meijer, E.; Calvel, B.; Laborie, A.; Monteiro, D.; Coatantiec, C.; Touzeau, S.; Erdmann, M.; Gare, P.



Basic Logic and Quantum Entanglement  

E-print Network

As it is well known, quantum entanglement is one of the most important features of quantum computing, as it leads to massive quantum parallelism, hence to exponential computational speed-up. In a sense, quantum entanglement is considered as an implicit property of quantum computation itself. But...can it be made explicit? In other words, is it possible to find the connective "entanglement" in a logical sequent calculus for the machine language? And also, is it possible to "teach" the quantum computer to "mimic" the EPR "paradox"? The answer is in the affirmative, if the logical sequent calculus is that of the weakest possible logic, namely Basic logic. A weak logic has few structural rules. But in logic, a weak structure leaves more room for connectives (for example the connective "entanglement"). Furthermore, the absence in Basic logic of the two structural rules of contraction and weakening corresponds to the validity of the no-cloning and no-erase theorems, respectively, in quantum computing.

Paola Zizzi



Algebraic thinking :A Basic Skill  

NSDL National Science Digital Library

This resource guide from the Middle School Portal 2 project, written specifically for teachers, provides links to exemplary resources including background information, lessons, career information, and related national science education standards. The resources highlighted here aim to reflect students growing mathematical capacity over the span of the middle school years. The activities and lessons, intended as supplementary materials, range from introduction to the fundamentals of algebra to work on linear functions. Uniformly, they take into consideration the preference of the middle school student for concrete models, visual representations, and interactive tasks. You will find resources on: Working with algebraic expressions, solving equations, understanding graphs, and moving from patterns to rules to functions. Some are games, others are online simulations that can complement a lesson, and yet others are full-blown lesson plans. We believe you will find tasks here that motivate your students to expand their basic skills in algebra.

Terese Herrera


78 FR 59121 - Basic Health Program: State Administration of Basic Health Programs; Eligibility and Enrollment...  

Federal Register 2010, 2011, 2012, 2013, 2014

...25, 2013 Part III Department of Health and Human Services...Administration of Basic Health Programs; Eligibility and Enrollment in Standard Health Plans; Essential...Standards for Basic Health Programs; Premium and Cost Sharing for Basic Health...



Severe Weather 101: Winter Weather Basics  


... Educators For Students For Everyone Severe Weather 101 Thunderstorms Basics Types Detection Forecasting FAQ Tornadoes Basics Types ... moisture. What we do: NSSL researchers studied winter thunderstorms and found that there is some evidence that ...


32 CFR 37.1240 - Basic research.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Basic research. 37.1240 Section 37...Part § 37.1240 Basic research. Efforts directed toward...knowledge and understanding in science and engineering, rather...typically is funded within Research, Development, Test and...



32 CFR 37.1240 - Basic research.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Basic research. 37.1240 Section 37...Part § 37.1240 Basic research. Efforts directed toward...knowledge and understanding in science and engineering, rather...typically is funded within Research, Development, Test and...



32 CFR 37.1240 - Basic research.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Basic research. 37.1240 Section 37...Part § 37.1240 Basic research. Efforts directed toward...understanding in science and engineering, rather than the practical...typically is funded within Research, Development, Test...



32 CFR 37.1240 - Basic research.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Basic research. 37.1240 Section 37...Part § 37.1240 Basic research. Efforts directed toward...understanding in science and engineering, rather than the practical...typically is funded within Research, Development, Test...



32 CFR 37.1240 - Basic research.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Basic research. 37.1240 Section 37...Part § 37.1240 Basic research. Efforts directed toward...understanding in science and engineering, rather than the practical...typically is funded within Research, Development, Test...



5 CFR 300.103 - Basic requirements.  

Code of Federal Regulations, 2010 CFR

... Basic requirements. (a) Job analysis. Each employment practice...individual agencies, shall be based on a job analysis to identify: (1) The evaluating candidates. The job analysis may cover a single position...



Basic Vocational Education Teacher Training Manual.  

ERIC Educational Resources Information Center

This instructor's guide consists of four modules teacher educators can use in preparing prospective teachers to teach basic vocational education students. The modules cover the following topics: (1) characteristics of basic vocational education students or students at risk for dropping out of high school; (2) program requirements of the basic

Thomas, Larry D.; And Others


Persian Basic Course: Units 1-12.  

ERIC Educational Resources Information Center

This basic course in Persian concentrates on the spoken language, illustrated by conversation based on everyday situations. After a thorough grounding in pronunciation and in basic grammatical features, the student is introduced to the writing system of Persian. Some of the basic differences between spoken and written styles are explained.…

Obolensky, Serge; And Others


Cryptography and Key Management Basics Erik Zenner  

E-print Network

Cryptography and Key Management Basics Erik Zenner Technical University Denmark (DTU) Institute for Mathematics DTU, Oct. 23, 2007 Erik Zenner (DTU-MAT) Cryptography and Key Management Basics DTU, Oct. 23, 2007 1 / 24 #12;Plan for Today 1 Talk 1: Cryptography and Key Management Basics

Zenner, Erik


Basics on Genes and Genetic Disorders  


The Basics on Genes and Genetic Disorders KidsHealth > Teens > Body > Health Basics > The Basics on Genes and Genetic Disorders Print A A A ... such as treating health problems. What Is a Gene? To understand how genes work, let's review some ...


Coordination for the Improvement of Basic Skills.  

ERIC Educational Resources Information Center

The Title II Basic Skills legislation, which is part of the Educational Amendments of 1978, requires coordination of basic skills improvement among related federally-supported programs. Coordination, while essential, is made difficult by the proliferation of agencies and bureaus concerned with basic skills and by the need for autonomy among…

Roberts, Jane M. E.


Fluid Power/Basic Hydraulics. Instructor's Guide.  

ERIC Educational Resources Information Center

This guide is designed to assist industrial vocational instructors in teaching a course on fluid power and basic hydraulics. Covered in the unit on the basics of fluid power and hydraulics are the following topics: the fundamentals of fluid power and hydraulics, basic hydraulic circuits, and servicing a hydraulic jack. The second unit, consisting…

Stanbery, Richard


Basic Communication Course Annual. Volume 11.  

ERIC Educational Resources Information Center

This volume of an annual collection presents eight essays relating to instruction in the basic communication course. The essays are: "The Basic Communication Course at U.S. Colleges and Universities: VI" (Sherwyn P. Morreale, Michael S. Hanna, Roy M. Berko, and James W. Gibson); "How Basic Course Directors Evaluate Teaching Assistants: Social…

Hugenberg, Lawrence W., Ed.


A Repeal of the Basic Writing Act.  

ERIC Educational Resources Information Center

The development of alternative instructional activities for use in the basic writing classroom and a description and analysis of four levels of basic writing are the results of a study of basic writing teaching techniques. The linguistic concepts of immediate and transferred utterances and nominal-verbal pairing, and the work of L. Vygotsky on…

Puma, Vincent D.


Twist1 activity thresholds define multiple functions in limb development  

PubMed Central

Summary The basic helix-loop-helix transcription factor Twist1 is essential for normal limb development. Twist1?/? embryos die at midgestation. However, studies on early limb buds found that Twist1?/? mutant limb mesenchyme has an impaired response to FGF signaling from the apical ectodermal ridge, which disrupts the feedback loop between the mesenchyme and AER, and reduces and shifts anteriorly Shh expression in the zone of polarizing activity. We have combined Twist1 null, hypomorph and conditional alleles to generate a Twist1 allelic series that survives to birth. As Twist1 activity is reduced, limb skeletal defects progress from preaxial polydactyly to girdle reduction combined with hypoplasia, aplasia or mirror symmetry of all limb segments. With reduced Twist1 activity there is striking and progressive upregulation of ectopic Shh expression in the anterior of the limb, combined with an anterior shift in the posterior Shh domain, which is expressed at normal intensity, and loss of the posterior AER. Consequently limb outgrowth is initially impaired, before an ectopic anterior Shh domain expands the AER, promoting additional growth and repatterning. Reducing the dosage of FGF targets of the Etv gene family, which are known repressors of Shh expression in the anterior limb mesenchyme, strongly enhances the anterior skeletal phenotype. Conversely this and other phenotypes are suppressed by reducing the dosage of the Twist1 antagonist Hand2. Our data support a model whereby multiple Twist1 activity thresholds contribute to early limb bud patterning, and suggest how particular combinations of skeletal defects result from differing amounts of Twist1 activity. PMID:20732316

Krawchuk, Dayana; Weiner, Shoshana J.; Chen, You-Tzung; Lu, Benson; Costantini, Frank; Behringer, Richard R.; Laufer, Ed



MondoA-Mlx Transcriptional Activity Is Limited by mTOR-MondoA Interaction.  


Mammalian target of rapamycin (mTOR) integrates multiple signals, including nutrient status, growth factor availability, and stress, to regulate cellular and organismal growth. How mTOR regulates transcriptional programs in response to these di