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Sample records for basic helix-loop-helix protein-mediated

  1. A classification of basic helix-loop-helix transcription factors of soybean.

    PubMed

    Hudson, Karen A; Hudson, Matthew E

    2015-01-01

    The complete genome sequence of soybean allows an unprecedented opportunity for the discovery of the genes controlling important traits. In particular, the potential functions of regulatory genes are a priority for analysis. The basic helix-loop-helix (bHLH) family of transcription factors is known to be involved in controlling a wide range of systems critical for crop adaptation and quality, including photosynthesis, light signalling, pigment biosynthesis, and seed pod development. Using a hidden Markov model search algorithm, 319 genes with basic helix-loop-helix transcription factor domains were identified within the soybean genome sequence. These were classified with respect to their predicted DNA binding potential, intron/exon structure, and the phylogeny of the bHLH domain. Evidence is presented that the vast majority (281) of these 319 soybean bHLH genes are expressed at the mRNA level. Of these soybean bHLH genes, 67% were found to exist in two or more homeologous copies. This dataset provides a framework for future studies on bHLH gene function in soybean. The challenge for future research remains to define functions for the bHLH factors encoded in the soybean genome, which may allow greater flexibility for genetic selection of growth and environmental adaptation in this widely grown crop. PMID:25763382

  2. 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...

  3. The basic helix-loop-helix transcription factor, Mist1, induces maturation of mouse fetal hepatoblasts.

    PubMed

    Chikada, Hiromi; Ito, Keiichi; Yanagida, Ayaka; Nakauchi, Hiromitsu; Kamiya, Akihide

    2015-01-01

    Hepatic stem/progenitor cells, hepatoblasts, have a high proliferative ability and can differentiate into mature hepatocytes and cholangiocytes. Therefore, these cells are considered to be useful for regenerative medicine and drug screening for liver diseases. However, it is problem that in vitro maturation of hepatoblasts is insufficient in the present culture system. In this study, a novel regulator to induce hepatic differentiation was identified and the molecular function of this factor was examined in embryonic day 13 hepatoblast culture with maturation factor, oncostatin M and extracellular matrices. Overexpression of the basic helix-loop-helix type transcription factor, Mist1, induced expression of mature hepatocytic markers such as carbamoyl-phosphate synthetase1 and several cytochrome P450 (CYP) genes in this culture system. In contrast, Mist1 suppressed expression of cholangiocytic markers such as Sox9, Sox17, Ck19, and Grhl2. CYP3A metabolic activity was significantly induced by Mist1 in this hepatoblast culture. In addition, Mist1 induced liver-enriched transcription factors, CCAAT/enhancer-binding protein α and Hepatocyte nuclear factor 1α, which are known to be involved in liver functions. These results suggest that Mist1 partially induces mature hepatocytic expression and function accompanied by the down-regulation of cholangiocytic markers. PMID:26456005

  4. A Triantagonistic Basic Helix-Loop-Helix System Regulates Cell Elongation in Arabidopsis[W][OA

    PubMed Central

    Ikeda, Miho; Fujiwara, Sumire; Mitsuda, Nobutaka; Ohme-Takagi, Masaru

    2012-01-01

    In plants, basic helix-loop-helix (bHLH) transcription factors play important roles in the control of cell elongation. Two bHLH proteins, PACLOBTRAZOL RESISTANCE1 (PRE1) and Arabidopsis ILI1 binding bHLH1 (IBH1), antagonistically regulate cell elongation in response to brassinosteroid and gibberellin signaling, but the detailed molecular mechanisms by which these factors regulate cell elongation remain unclear. Here, we identify the bHLH transcriptional activators for cell elongation (ACEs) and demonstrate that PRE1, IBH1, and the ACEs constitute a triantagonistic bHLH system that competitively regulates cell elongation. In this system, the ACE bHLH transcription factors directly activate the expression of enzyme genes for cell elongation by interacting with their promoter regions. IBH1 negatively regulates cell elongation by interacting with the ACEs and thus interfering with their DNA binding. PRE1 interacts with IBH1 and counteracts the ability of IBH1 to affect ACEs. Therefore, PRE1 restores the transcriptional activity of ACEs, resulting in induction of cell elongation. The balance of triantagonistic bHLH proteins, ACEs, IBH1, and PRE1, might be important for determination of the size of plant cells. The expression of IBH1 and PRE1 is regulated by brassinosteroid, gibberellins, and developmental phase dependent factors, indicating that two phytohormones and phase-dependent signals are integrated by this triantagonistic bHLH system. PMID:23161888

  5. The basic helix-loop-helix transcription factor, dHAND, is required for vascular development

    PubMed Central

    Yamagishi, Hiroyuki; Olson, Eric N.; Srivastava, Deepak

    2000-01-01

    Reciprocal interactions between vascular endothelial cells and vascular mesenchymal cells are essential for angiogenesis. Here we show that the basic helix-loop-helix transcription factor, dHAND/Hand2, is expressed in the developing vascular mesenchyme and its derivative, vascular smooth muscle cells (VSMCs). Targeted deletion of the dHAND gene in mice revealed severe defects of embryonic and yolk sac vascular development by embryonic day 9.5. Vascular endothelial cells expressed most markers of differentiation. Vascular mesenchymal cells migrated appropriately but failed to make contact with vascular endothelial cells and did not differentiate into VSMCs. In a screen for genes whose expression was dependent upon dHAND (using subtractive hybridization comparing wild-type and dHAND-null hearts), the VEGF165 receptor, neuropilin-1, was found to be downregulated in dHAND mutants. These results suggest that dHAND is required for vascular development and regulates angiogenesis, possibly through a VEGF signaling pathway. PMID:10675351

  6. The basic helix-loop-helix transcription factor, Mist1, induces maturation of mouse fetal hepatoblasts

    PubMed Central

    Chikada, Hiromi; Ito, Keiichi; Yanagida, Ayaka; Nakauchi, Hiromitsu; Kamiya, Akihide

    2015-01-01

    Hepatic stem/progenitor cells, hepatoblasts, have a high proliferative ability and can differentiate into mature hepatocytes and cholangiocytes. Therefore, these cells are considered to be useful for regenerative medicine and drug screening for liver diseases. However, it is problem that in vitro maturation of hepatoblasts is insufficient in the present culture system. In this study, a novel regulator to induce hepatic differentiation was identified and the molecular function of this factor was examined in embryonic day 13 hepatoblast culture with maturation factor, oncostatin M and extracellular matrices. Overexpression of the basic helix-loop-helix type transcription factor, Mist1, induced expression of mature hepatocytic markers such as carbamoyl-phosphate synthetase1 and several cytochrome P450 (CYP) genes in this culture system. In contrast, Mist1 suppressed expression of cholangiocytic markers such as Sox9, Sox17, Ck19, and Grhl2. CYP3A metabolic activity was significantly induced by Mist1 in this hepatoblast culture. In addition, Mist1 induced liver-enriched transcription factors, CCAAT/enhancer-binding protein α and Hepatocyte nuclear factor 1α, which are known to be involved in liver functions. These results suggest that Mist1 partially induces mature hepatocytic expression and function accompanied by the down-regulation of cholangiocytic markers. PMID:26456005

  7. Iron-binding E3 ligase mediates iron response in plants by targeting basic helix-loop-helix transcription factors.

    PubMed

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

    2015-01-01

    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::β-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

  8. TFEC, a basic helix-loop-helix protein, forms heterodimers with TFE3 and inhibits TFE3-dependent transcription activation.

    PubMed Central

    Zhao, G Q; Zhao, Q; Zhou, X; Mattei, M G; de Crombrugghe, B

    1993-01-01

    We have identified a new basic helix-loop-helix (BHLH) DNA-binding protein, designated TFEC, which is closely related to TFE3 and TFEB. The basic domain of TFEC is identical to the basic DNA-binding domain of TFE3 and TFEB, whereas the helix-loop-helix motif of TFEC shows 88 and 85% identity with the same domains in TFE3 and TFEB, respectively. Like the other two proteins, TFEC contains a leucine zipper motif, which has a lower degree of sequence identity with homologous domains in TFE3 and TFEB than does the BHLH segment. Little sequence identity exists outside these motifs. Unlike the two other proteins, TFEC does not contain an acidic domain, which for TFE3 mediates the ability to activate transcription. Like the in vitro translation product of TFE3, the in vitro-translated TFEC binds to the mu E3 DNA sequence of the immunoglobulin heavy-chain gene enhancer. In addition, the product of cotranslation of TFEC RNA and TFE3 RNA forms a heteromeric protein-DNA complex with mu E3 DNA. In contrast to TFE3, TFEC is unable to transactivate a reporter gene linked to a promoter containing tandem copies of the immunoglobulin mu E3 enhancer motif. Cotransfection of TFEC DNA and TFE3 DNA strongly inhibits the transactivation caused by TFE3. TFEC RNA is found in many tissues of adult rats, but the relative concentrations of TFEC and TFE3 RNAs vary considerably in these different tissues. No TFEC RNA was detectable in several cell lines, including fibroblasts, myoblasts, chondrosarcoma cells, and myeloma cells, indicating that TFEC is not ubiquitously expressed. Images PMID:8336698

  9. A basic helix-loop-helix transcription factor, PhFBH4, regulates flower senescence by modulating ethylene biosynthesis pathway in petunia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The basic helix-loop-helix (bHLH) transcription factors (TFs) play important roles in regulating multiple biological processes in plants. However, there are few reports about the function of bHLHs in flower senescence. In this study, a bHLH TF, PhFBH4, was found to be dramatically upregulated during...

  10. The Basic Helix-Loop-Helix Transcription Factor NEUROG3 Is Required for Development of the Human Endocrine Pancreas.

    PubMed

    McGrath, Patrick S; Watson, Carey L; Ingram, Cameron; Helmrath, Michael A; Wells, James M

    2015-07-01

    Neurogenin3 (NEUROG3) is a basic helix-loop-helix transcription factor required for development of the endocrine pancreas in mice. In contrast, humans with NEUROG3 mutations are born with endocrine pancreas function, calling into question whether NEUROG3 is required for human endocrine pancreas development. To test this directly, we generated human embryonic stem cell (hESC) lines where both alleles of NEUROG3 were disrupted using CRISPR/Cas9-mediated gene targeting. NEUROG3(-/-) hESC lines efficiently formed pancreatic progenitors but lacked detectible NEUROG3 protein and did not form endocrine cells in vitro. Moreover, NEUROG3(-/-) hESC lines were unable to form mature pancreatic endocrine cells after engraftment of PDX1(+)/NKX6.1(+) pancreatic progenitors into mice. In contrast, a 75-90% knockdown of NEUROG3 caused a reduction, but not a loss, of pancreatic endocrine cell development. We conclude that NEUROG3 is essential for endocrine pancreas development in humans and that as little as 10% NEUROG3 is sufficient for formation of pancreatic endocrine cells. PMID:25650326

  11. Genome-wide features of neuroendocrine regulation in Drosophila by the basic helix-loop-helix transcription factor DIMMED

    PubMed Central

    Hadžić, Tarik; Park, Dongkook; Abruzzi, Katharine C.; Yang, Lin; Trigg, Jennifer S.; Rohs, Remo; Rosbash, Michael; Taghert, Paul H.

    2015-01-01

    Neuroendocrine (NE) cells use large dense core vesicles (LDCVs) to traffic, process, store and secrete neuropeptide hormones through the regulated secretory pathway. The dimmed (DIMM) basic helix-loop-helix transcription factor of Drosophila controls the level of regulated secretory activity in NE cells. To pursue its mechanisms, we have performed two independent genome-wide analyses of DIMM's activities: (i) in vivo chromatin immunoprecipitation (ChIP) to define genomic sites of DIMM occupancy and (ii) deep sequencing of purified DIMM neurons to characterize their transcriptional profile. By this combined approach, we showed that DIMM binds to conserved E-boxes in enhancers of 212 genes whose expression is enriched in DIMM-expressing NE cells. DIMM binds preferentially to certain E-boxes within first introns of specific gene isoforms. Statistical machine learning revealed that flanking regions of putative DIMM binding sites contribute to its DNA binding specificity. DIMM's transcriptional repertoire features at least 20 LDCV constituents. In addition, DIMM notably targets the pro-secretory transcription factor, creb-A, but significantly, DIMM does not target any neuropeptide genes. DIMM therefore prescribes the scale of secretory activity in NE neurons, by a systematic control of both proximal and distal points in the regulated secretory pathway. PMID:25634895

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

    PubMed Central

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

    2004-01-01

    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

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

    PubMed Central

    Chen, Deyu

    2013-01-01

    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

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

    PubMed Central

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

    2002-01-01

    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

  15. GLABRA2 Directly Suppresses Basic Helix-Loop-Helix Transcription Factor Genes with Diverse Functions in Root Hair Development

    PubMed Central

    Lin, Qing; Ohashi, Yohei; Kato, Mariko; Tsuge, Tomohiko; Gu, Hongya; Qu, Li-Jia; Aoyama, Takashi

    2015-01-01

    The Arabidopsis thaliana GLABRA2 (GL2) gene encodes a transcription factor involved in the cell differentiation of various epidermal tissues. During root hair pattern formation, GL2 suppresses root hair development in non-hair cells, acting as a node between the gene regulatory networks for cell fate determination and cell differentiation. Despite the importance of GL2 function, its molecular basis remains obscure because the GL2 target genes leading to the network for cell differentiation are unknown. We identified five basic helix-loop-helix (bHLH) transcription factor genes—ROOT HAIR DEFECTIVE6 (RHD6), RHD6-LIKE1 (RSL1), RSL2, LjRHL1-LIKE1 (LRL1), and LRL2—as GL2 direct targets using transcriptional and post-translational induction systems. Chromatin immunoprecipitation analysis confirmed GL2 binding to upstream regions of these genes in planta. Reporter gene analyses showed that these genes are expressed in various stages of root hair development and are suppressed by GL2 in non-hair cells. GL2 promoter-driven green fluorescent protein fusions of LRL1 and LRL2, but not those of the other bHLH proteins, conferred root hair development on non-hair cells. These results indicate that GL2 directly suppresses bHLH genes with diverse functions in root hair development. PMID:26486447

  16. A novel type of calmodulin interaction in the inhibition of basic helix-loop-helix transcription factors.

    PubMed

    Onions, J; Hermann, S; Grundström, T

    2000-04-18

    Calmodulin is the predominant intracellular receptor for Ca(2+) signals, mediating the regulation of numerous cellular processes. Previous studies have shown that calcium-loaded calmodulin can bind to and inhibit the activity of certain basic helix-loop-helix (bHLH) transcription factors. The basic sequence within the bHLH domain is the primary target for calmodulin binding, and sequences modulating the calmodulin interaction reside directly N-terminal to the basic sequence. Here we show that the interaction of calmodulin with bHLH proteins is of a novel type, displaying characteristics very different from those of previously characterized calmodulin-target complexes. We show that calmodulin interacts much stronger with a dimeric basic sequence than with the monomeric form. The calmodulin-bHLH protein complex contains equimolar amounts of calmodulin and bHLH chains. The interaction is unusual in being to a large extent polar in nature, and it is highly resistant to tested calmodulin inhibitors. Both the N-terminal and C-terminal domains of calmodulin can independently bind to and inhibit the DNA binding of bHLH proteins. The C-terminal domain preferentially binds to the basic sequence, whereas the N-terminal domain is essential for the effect of the modulatory sequence. We propose a model for the calmodulin-bHLH complex where two calmodulin molecules interact with one bHLH dimer, with one domain of calmodulin preferentially binding to the basic sequence of bHLH proteins and the other domain interacting with the modulatory sequence. PMID:10757985

  17. ZmZHOUPI, an endosperm-specific basic helix-loop-helix transcription factor involved in maize seed development.

    PubMed

    Grimault, Aurélie; Gendrot, Ghislaine; Chamot, Sophy; Widiez, Thomas; Rabillé, Hervé; Gérentes, Marie-France; Creff, Audrey; Thévenin, Johanne; Dubreucq, Bertrand; Ingram, Gwyneth C; Rogowsky, Peter M; Depège-Fargeix, Nathalie

    2015-11-01

    In angiosperm seeds the embryo is embedded within the endosperm, which is in turn enveloped by the seed coat, making inter-compartmental communication essential for coordinated seed growth. In this context the basic helix-loop-helix domain transcription factor AtZHOUPI (AtZOU) fulfils a key role in both the lysis of the transient endosperm and in embryo cuticle formation in Arabidopsis thaliana. In maize (Zea mays), a cereal with a persistent endosperm, a single gene, ZmZOU, falls into the same phylogenetic clade as AtZOU. Its expression is limited to the endosperm where it peaks during the filling stage. In ZmZOU-RNA interference knock-down lines embryo size is slightly reduced and the embryonic suspensor and the adjacent embryo surrounding region show retarded breakdown. Ectopic expression of ZmZOU reduces stomatal number, possibly due to inappropriate protein interactions. ZmZOU forms functional heterodimers with AtICE/AtSCREAM and the closely related maize proteins ZmICEb and ZmICEc, but its interaction is more efficient with the ZmICEa protein, which shows sequence divergence and only has close homologues in other monocotyledonous species. Consistent with the observation that these complexes can trans-activate target gene promoters from Arabidopsis, ZmZOU partially complements the Atzou-4 mutant. However, structural, trans-activation and gene expression data support the hypothesis that ZmZOU and ZmICEa may have coevolved to form a functional complex unique to monocot seeds. This divergence may explain the reduced functionality of ZmZOU in Arabidopsis, and reflect functional specificities which are unique to the monocotyledon lineage. PMID:26361885

  18. An Arabidopsis Basic Helix-Loop-Helix Leucine Zipper Protein Modulates Metal Homeostasis and Auxin Conjugate Responsiveness

    PubMed Central

    Rampey, Rebekah A.; Woodward, Andrew W.; Hobbs, Brianne N.; Tierney, Megan P.; Lahner, Brett; Salt, David E.; Bartel, Bonnie

    2006-01-01

    The plant hormone auxin can be regulated by formation and hydrolysis of amide-linked indole-3-acetic acid (IAA) conjugates. Here, we report the characterization of the dominant Arabidopsis iaa–leucine resistant3 (ilr3-1) mutant, which has reduced sensitivity to IAA–Leu and IAA–Phe, while retaining wild-type responses to free IAA. The gene defective in ilr3-1 encodes a basic helix-loop-helix leucine zipper protein, bHLH105, and the ilr3-1 lesion results in a truncated product. Overexpressing ilr3-1 in wild-type plants recapitulates certain ilr3-1 mutant phenotypes. In contrast, the loss-of-function ilr3-2 allele has increased IAA–Leu sensitivity compared to wild type, indicating that the ilr3-1 allele confers a gain of function. Microarray and quantitative real-time PCR analyses revealed five downregulated genes in ilr3-1, including three encoding putative membrane proteins similar to the yeast iron and manganese transporter Ccc1p. Transcript changes are accompanied by reciprocally misregulated metal accumulation in ilr3-1 and ilr3-2 mutants. Further, ilr3-1 seedlings are less sensitive than wild type to manganese, and auxin conjugate response phenotypes are dependent on exogenous metal concentration in ilr3 mutants. These data suggest a model in which the ILR3/bHLH105 transcription factor regulates expression of metal transporter genes, perhaps indirectly modulating IAA-conjugate hydrolysis by controlling the availability of metals previously shown to influence IAA–amino acid hydrolase protein activity. PMID:17028341

  19. Origin and diversification of the basic helix-loop-helix gene family in metazoans: insights from comparative genomics

    PubMed Central

    Simionato, Elena; Ledent, Valérie; Richards, Gemma; Thomas-Chollier, Morgane; Kerner, Pierre; Coornaert, David; Degnan, Bernard M; Vervoort, Michel

    2007-01-01

    Background Molecular and genetic analyses conducted in model organisms such as Drosophila and vertebrates, have provided a wealth of information about how networks of transcription factors control the proper development of these species. Much less is known, however, about the evolutionary origin of these elaborated networks and their large-scale evolution. Here we report the first evolutionary analysis of a whole superfamily of transcription factors, the basic helix-loop-helix (bHLH) proteins, at the scale of the whole metazoan kingdom. Results We identified in silico the putative full complement of bHLH genes in the sequenced genomes of 12 different species representative of the main metazoan lineages, including three non-bilaterian metazoans, the cnidarians Nematostella vectensis and Hydra magnipapillata and the demosponge Amphimedon queenslandica. We have performed extensive phylogenetic analyses of the 695 identified bHLHs, which has allowed us to allocate most of these bHLHs to defined evolutionary conserved groups of orthology. Conclusion Three main features in the history of the bHLH gene superfamily can be inferred from these analyses: (i) an initial diversification of the bHLHs has occurred in the pre-Cambrian, prior to metazoan cladogenesis; (ii) a second expansion of the bHLH superfamily occurred early in metazoan evolution before bilaterians and cnidarians diverged; and (iii) the bHLH complement during the evolution of the bilaterians has been remarkably stable. We suggest that these features may be extended to other developmental gene families and reflect a general trend in the evolution of the developmental gene repertoires of metazoans. PMID:17335570

  20. The Basic/Helix-Loop-Helix Protein Family in Gossypium: Reference Genes and Their Evolution during Tetraploidization.

    PubMed

    Yan, Qian; Liu, Hou-Sheng; Yao, Dan; Li, Xin; Chen, Han; Dou, Yang; Wang, Yi; Pei, Yan; Xiao, Yue-Hua

    2015-01-01

    Basic/helix-loop-helix (bHLH) proteins comprise one of the largest transcription factor families and play important roles in diverse cellular and molecular processes. Comprehensive analyses of the composition and evolution of the bHLH family in cotton are essential to elucidate their functions and the molecular basis of cotton development. By searching bHLH homologous genes in sequenced diploid cotton genomes (Gossypium raimondii and G. arboreum), a set of cotton bHLH reference genes containing 289 paralogs were identified and named as GobHLH001-289. Based on their phylogenetic relationships, these cotton bHLH proteins were clustered into 27 subfamilies. Compared to those in Arabidopsis and cacao, cotton bHLH proteins generally increased in number, but unevenly in different subfamilies. To further uncover evolutionary changes of bHLH genes during tetraploidization of cotton, all genes of S5a and S5b subfamilies in upland cotton and its diploid progenitors were cloned and compared, and their transcript profiles were determined in upland cotton. A total of 10 genes of S5a and S5b subfamilies (doubled from A- and D-genome progenitors) maintained in tetraploid cottons. The major sequence changes in upland cotton included a 15-bp in-frame deletion in GhbHLH130D and a long terminal repeat retrotransposon inserted in GhbHLH062A, which eliminated GhbHLH062A expression in various tissues. The S5a and S5b bHLH genes of A and D genomes (except GobHLH062) showed similar transcription patterns in various tissues including roots, stems, leaves, petals, ovules, and fibers, while the A- and D-genome genes of GobHLH110 and GobHLH130 displayed clearly different transcript profiles during fiber development. In total, this study represented a genome-wide analysis of cotton bHLH family, and revealed significant changes in sequence and expression of these genes in tetraploid cottons, which paved the way for further functional analyses of bHLH genes in the cotton genus. PMID:25992947

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

    PubMed Central

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

    2015-01-01

    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::β-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

  2. The activation domain of a basic helix-loop-helix protein is masked by repressor interaction with domains distinct from that required for transcription regulation.

    PubMed Central

    Jayaraman, P S; Hirst, K; Goding, C R

    1994-01-01

    While there are many examples of protein-protein interactions modulating the DNA-binding activity of transcription factors, little is known of the molecular mechanisms underlying the regulation of the transcription activation function. Using a two-hybrid system we show here that transcription repression of the basic domain/helix-loop-helix factor PHO4 is mediated by complex formation with the PHO80 repressor. In contrast to other systems, such as inhibition of GAL4 by GAL80 or of p53 by MDM2, where repression is mediated by direct interaction at regions overlapping the transcription activation domain, interaction with PHO80 involves two regions of PHO4 distinct from those involved in transcription activation or DNA-binding and dimerization. The possibility that repression of PHO4 by PHO80 may represent a general mechanism of transcription control, including regulation of the cell-type-specific transcription activation domain of c-Jun, is discussed. Images PMID:8187772

  3. Dynamic Antagonism between Phytochromes and PIF Family Basic Helix-Loop-Helix Factors Induces Selective Reciprocal Responses to Light and Shade in a Rapidly Responsive Transcriptional Network in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants respond to shade-modulated light signals via phytochrome (phy)-induced adaptive changes, termed shade avoidance. To examine the roles of Phytochrome-Interacting basic helix-loop-helix Factors, PIF1, 3, 4, and 5, in relaying such signals to the transcriptional network, we compared the shade-re...

  4. 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

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

    1997-01-01

    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

  5. Mutations in TCF12, encoding a basic helix-loop-helix partner of TWIST1, are a frequent cause of coronal craniosynostosis.

    PubMed

    Sharma, Vikram P; Fenwick, Aimée L; Brockop, Mia S; McGowan, Simon J; Goos, Jacqueline A C; Hoogeboom, A Jeannette M; Brady, Angela F; Jeelani, Nu Owase; Lynch, Sally Ann; Mulliken, John B; Murray, Dylan J; Phipps, Julie M; Sweeney, Elizabeth; Tomkins, Susan E; Wilson, Louise C; Bennett, Sophia; Cornall, Richard J; Broxholme, John; Kanapin, Alexander; Johnson, David; Wall, Steven A; van der Spek, Peter J; Mathijssen, Irene M J; Maxson, Robert E; Twigg, Stephen R F; Wilkie, Andrew O M

    2013-03-01

    Craniosynostosis, the premature fusion of the cranial sutures, is a heterogeneous disorder with a prevalence of ∼1 in 2,200 (refs. 1,2). A specific genetic etiology can be identified in ∼21% of cases, including mutations of TWIST1, which encodes a class II basic helix-loop-helix (bHLH) transcription factor, and causes Saethre-Chotzen syndrome, typically associated with coronal synostosis. Using exome sequencing, we identified 38 heterozygous TCF12 mutations in 347 samples from unrelated individuals with craniosynostosis. The mutations predominantly occurred in individuals with coronal synostosis and accounted for 32% and 10% of subjects with bilateral and unilateral pathology, respectively. TCF12 encodes one of three class I E proteins that heterodimerize with class II bHLH proteins such as TWIST1. We show that TCF12 and TWIST1 act synergistically in a transactivation assay and that mice doubly heterozygous for loss-of-function mutations in Tcf12 and Twist1 have severe coronal synostosis. Hence, the dosage of TCF12-TWIST1 heterodimers is critical for normal coronal suture development. PMID:23354436

  6. Molecular characterization of cold-responsive basic helix-loop-helix transcription factors MabHLHs that interact with MaICE1 in banana fruit.

    PubMed

    Peng, Huan-Huan; Shan, Wei; Kuang, Jian-Fei; Lu, Wang-Jin; Chen, Jian-Ye

    2013-11-01

    Basic helix-loop-helix (bHLH) transcription factors (TFs) are ubiquitously involved in the response of higher plants to various abiotic stresses. However, little is known about bHLH TFs involved in the cold stress response in economically important fruits. Here, five novel full-length bHLH genes, designated as MabHLH1-MabHLH5, were isolated and characterized from banana fruit. Gene expression profiles revealed that MabHLH1/2/4 were induced by cold stress and methyl jasmonate (MeJA) treatment. Transient assays in tobacco BY2 protoplasts showed that MabHLH1/2/4 promoters were activated by cold stress and MeJA treatments. Moreover, protein-protein interaction analysis demonstrated that MabHLH1/2/4 not only physically interacted with each other to form hetero-dimers in the nucleus, but also interacted with an important upstream component of cold signaling MaICE1, with different interaction domains at their N-terminus. These results indicate that banana fruit cold-responsive MabHLHs may form a big protein complex in the nucleus with MaICE1. Taken together, our findings advance our understanding of the possible involvement of bHLH TFs in the regulatory network of ICE-CBF cold signaling pathway. PMID:23955147

  7. Effects of postweaning administration of conjugated linoleic acid on development of obesity in nescient basic helix-loop-helix 2 knockout mice.

    PubMed

    Kim, Yoo; Kim, Daeyoung; Good, Deborah J; Park, Yeonhwa

    2015-06-01

    Conjugated linoleic acid (CLA) has been reported to prevent body weight gain and fat accumulation in part by improving physical activity in mice. However, the effects of postweaning administration of CLA on the development of obesity later in life have not yet been demonstrated. The current study investigated the role of postweaning CLA treatment on skeletal muscle energy metabolism in genetically induced inactive adult-onset obese model, nescient basic helix-loop-helix 2 knockout (N2KO) mice. Four-week-old male N2KO and wild type mice were fed either control or a CLA-containing diet (0.5%) for 4 weeks, and then CLA was withdrawn and control diet provided to all mice for the following 8 weeks. Postweaning CLA supplementation in wild type animals, but not N2KO mice, may activate AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor-δ (PPARδ) as well as promote desensitization of phosphatase and tensin homologue (PTEN) and sensitization of protein kinase B (AKT) at threonine 308 in gastrocnemius skeletal muscle, improving voluntary activity and glucose homeostasis. We suggest that postweaning administration of CLA may in part stimulate the underlying molecular targets involved in muscle energy metabolism to reduce weight gain in normal animals, but not in the genetically induced inactive adult-onset animal model. PMID:25976059

  8. Transcriptome-wide analysis of basic helix-loop-helix transcription factors in Isatis indigotica and their methyl jasmonate responsive expression profiling.

    PubMed

    Zhang, Lei; Chen, Junfeng; Li, Qing; Chen, Wansheng

    2016-01-15

    Jasmonates (JAs) act as conserved elicitors of plant secondary metabolism. JAs perception triggers extensive transcriptional reprogramming leading to activation of the entire metabolic pathways. The family of basic helix-loop-helix (bHLH) transcription factors (TFs) has essential roles in JA signaling; however, little is known about their roles in regulation of secondary metabolites in Isatis indigotica. In this study, we identified 78 putative IibHLH sequences using the annotation of I. indigotica transcriptome. The identified proteins were characterized based on phylogenetic and conserved motif analyses. Using RNA sequencing, 16 IibHLHs showed significant positive response to MeJA (methyl jasmonate) at 1h, indicating their roles as early signaling events of JA-mediated transcriptional reprogramming. Ten IibHLHs presented co-expression pattern with biosynthetic pathway genes, suggesting their regulating role in secondary metabolite synthesis. These gene expression profiling data indicate that bHLHs can be used as candidate genes in molecular breeding programs to improve metabolite production in I. indigotica. PMID:26449398

  9. Mutations of TCF12, encoding a basic-helix-loop-helix partner of TWIST1, are a frequent cause of coronal craniosynostosis

    PubMed Central

    Sharma, Vikram P; Fenwick, Aimée L; Brockop, Mia S; McGowan, Simon J; Goos, Jacqueline A C; Hoogeboom, A Jeannette M; Brady, Angela F; Jeelani, N u Owase; Lynch, Sally Ann; Mulliken, John B; Murray, Dylan J; Phipps, Julie M; Sweeney, Elizabeth; Tomkins, Susan E; Wilson, Louise C; Bennett, Sophia; Cornall, Richard J; Broxholme, John; Kanapin, Alexander; Johnson, David; Wall, Steven A; van der Spek, Peter J; Mathijssen, Irene M J; Maxson, Robert E; Twigg, Stephen R F; Wilkie, Andrew O M

    2013-01-01

    Craniosynostosis, the premature fusion of the cranial sutures, is a heterogeneous disorder with a prevalence of ~1 in 2,200 (refs. 1,2). A specific genetic etiology can be identified in ~21% of cases3, including mutations of TWIST1, which encodes a class II basic helix-loop-helix (bHLH) transcription factor, and causes Saethre-Chotzen syndrome, typically associated with coronal synostosis4-6. Starting with an exome sequencing screen, we identified 38 heterozygous TCF12 mutations in 347 samples from unrelated individuals with craniosynostosis. The mutations predominantly occurred in patients with coronal synostosis and accounted for 32% and 10% of subjects with bilateral and unilateral pathology, respectively. TCF12 encodes one of three class I E-proteins that heterodimerize with class II bHLH proteins such as TWIST1. We show that TCF12 and TWIST1 act synergistically in a transactivation assay, and that mice doubly heterozygous for loss-of-function mutations in Tcf12 and Twist1 exhibit severe coronal synostosis. Hence, the dosage of TCF12/TWIST1 heterodimers is critical for coronal suture development. PMID:23354436

  10. The Basic Helix-Loop-Helix Transcription Factor E47 Reprograms Human Pancreatic Cancer Cells to a Quiescent Acinar State With Reduced Tumorigenic Potential

    PubMed Central

    Kim, SangWun; Lahmy, Reyhaneh; Riha, Chelsea; Yang, Challeng; Jakubison, Brad L.; van Niekerk, Jaco; Staub, Claudio; Wu, Yifan; Gates, Keith; Dong, Duc Si; Konieczny, Stephen F.; Itkin-Ansari, Pamela

    2015-01-01

    Objectives Pancreatic ductal adenocarcinoma (PDA) initiates from quiescent acinar cells that attain a Kras mutation, lose signaling from basic helix-loop-helix (bHLH) transcription factors, undergo acinar-ductal metaplasia, and rapidly acquire increased growth potential. We queried whether PDA cells can be reprogrammed to revert to their original quiescent acinar cell state by shifting key transcription programs. Methods Human PDA cell lines were engineered to express an inducible form of the bHLH protein E47. Gene expression, growth, and functional studies were investigated using microarray, quantitative polymerase chain reaction, immunoblots, immunohistochemistry, small interfering RNA, chromatin immunoprecipitation analyses, and cell transplantation into mice. Results In human PDA cells, E47 activity triggers stable G0/G1 arrest, which requires the cyclin-dependent kinase inhibitor p21 and the stress response protein TP53INP1. Concurrently, E47 induces high level expression of acinar digestive enzymes and feed forward activation of the acinar maturation network regulated by the bHLH factor MIST1. Moreover, induction of E47 in human PDA cells in vitro is sufficient to inhibit tumorigenesis. Conclusions Human PDA cells retain a high degree of plasticity, which can be exploited to induce a quiescent acinar cell state with reduced tumorigenic potential. Moreover, bHLH activity is a critical node coordinately regulating human PDA cell growth versus cell fate. PMID:25894862

  11. A basic helix-loop-helix transcription factor, PhFBH4, regulates flower senescence by modulating ethylene biosynthesis pathway in petunia

    PubMed Central

    Yin, Jing; Chang, Xiaoxiao; Kasuga, Takao; Bui, Mai; Reid, Michael S; Jiang, Cai-Zhong

    2015-01-01

    The basic helix-loop-helix (bHLH) transcription factors (TFs) play important roles in regulating multiple biological processes in plants. However, there are few reports about the function of bHLHs in flower senescence. In this study, a bHLH TF, PhFBH4, was found to be dramatically upregulated during flower senescence. Transcription of PhFBH4 is induced by plant hormones and abiotic stress treatments. Silencing of PhFBH4 using virus-induced gene silencing or an antisense approach extended flower longevity, while transgenic petunia flowers with an overexpression construct showed a reduction in flower lifespan. Abundance of transcripts of senescence-related genes (SAG12, SAG29) was significantly changed in petunia PhFBH4 transgenic flowers. Furthermore, silencing or overexpression of PhFBH4 reduced or increased, respectively, transcript abundances of important ethylene biosynthesis-related genes, ACS1 and ACO1, thereby influencing ethylene production. An electrophoretic mobility shift assay showed that the PhFBH4 protein physically interacted with the G-box cis-element in the promoter of ACS1, suggesting that ACS1 was a direct target of the PhFBH4 protein. In addition, ectopic expression of this gene altered plant development including plant height, internode length, and size of leaves and flowers, accompanied by alteration of transcript abundance of the gibberellin biosynthesis-related gene GA2OX3. Our results indicate that PhFBH4 plays an important role in regulating plant growth and development through modulating the ethylene biosynthesis pathway. PMID:26715989

  12. The poplar basic helix-loop-helix transcription factor BEE3 - Like gene affects biomass production by enhancing proliferation of xylem cells in poplar.

    PubMed

    Noh, Seol Ah; Choi, Young-Im; Cho, Jin-Seong; Lee, Hyoshin

    2015-06-19

    Brassinosteroids (BRs) play important roles in many aspects of plant growth and development, including regulation of vascular cambium activities and cell elongation. BR-induced BEE3 (brassinosteroid enhanced expression 3) is required for a proper BR response. Here, we identified a poplar (Populus alba × Populus glandulosa) BEE3-like gene, PagBEE3L, encoding a putative basic helix-loop-helix (bHLH)-type transcription factor. Expression of PagBEE3L was induced by brassinolide (BL). Transcripts of PagBEE3L were mainly detected in stems, with the internode having a low level of transcription and the node having a relatively higher level. The function of the PagBEE3L gene was investigated through phenotypic analyses with PagBEE3L-overexpressing (ox) transgenic lines. This work particularly focused on a potential role of PagBEE3L in stem growth and development of polar. The PagBEE3L-ox poplar showed thicker and longer stems than wild-type plants. The xylem cells from the stems of PagBEE3L-ox plants revealed remarkably enhanced proliferation, resulting in an earlier thickening growth than wild-type plants. Therefore, this work suggests that xylem development of poplar is accelerated in PagBEE3L-ox plants and PagBEE3L plays a role in stem growth by increasing the proliferation of xylem cells to promote the initial thickening growth of poplar stems. PMID:25935487

  13. A basic helix-loop-helix transcription factor, PhFBH4, regulates flower senescence by modulating ethylene biosynthesis pathway in petunia.

    PubMed

    Yin, Jing; Chang, Xiaoxiao; Kasuga, Takao; Bui, Mai; Reid, Michael S; Jiang, Cai-Zhong

    2015-01-01

    The basic helix-loop-helix (bHLH) transcription factors (TFs) play important roles in regulating multiple biological processes in plants. However, there are few reports about the function of bHLHs in flower senescence. In this study, a bHLH TF, PhFBH4, was found to be dramatically upregulated during flower senescence. Transcription of PhFBH4 is induced by plant hormones and abiotic stress treatments. Silencing of PhFBH4 using virus-induced gene silencing or an antisense approach extended flower longevity, while transgenic petunia flowers with an overexpression construct showed a reduction in flower lifespan. Abundance of transcripts of senescence-related genes (SAG12, SAG29) was significantly changed in petunia PhFBH4 transgenic flowers. Furthermore, silencing or overexpression of PhFBH4 reduced or increased, respectively, transcript abundances of important ethylene biosynthesis-related genes, ACS1 and ACO1, thereby influencing ethylene production. An electrophoretic mobility shift assay showed that the PhFBH4 protein physically interacted with the G-box cis-element in the promoter of ACS1, suggesting that ACS1 was a direct target of the PhFBH4 protein. In addition, ectopic expression of this gene altered plant development including plant height, internode length, and size of leaves and flowers, accompanied by alteration of transcript abundance of the gibberellin biosynthesis-related gene GA2OX3. Our results indicate that PhFBH4 plays an important role in regulating plant growth and development through modulating the ethylene biosynthesis pathway. PMID:26715989

  14. The basic helix-loop-helix protein upstream stimulating factor regulates the cardiac ventricular myosin light-chain 2 gene via independent cis regulatory elements.

    PubMed Central

    Navankasattusas, S; Sawadogo, M; van Bilsen, M; Dang, C V; Chien, K R

    1994-01-01

    Previous studies have documented that 250 bp of the rat cardiac ventricular myosin light-chain 2 (MLC-2v) promoter is sufficient to confer cardiac muscle-specific expression on a luciferase reporter gene in both transgenic mice and primary cultured neonatal rat myocardial cells. Utilizing ligation-mediated PCR to perform in vivo dimethyl sulfate footprinting, the present study has identified protein-DNA interaction within the position from -176 to -165. This region, identified as MLE1, contains a core sequence, CACGTG, which conforms to the consensus E-box site and is identical to the upstream stimulating factor (USF)-binding site of the adenovirus major late promoter. Transient assays of luciferase reporter genes containing point mutations of the site demonstrate the importance of this cis regulatory element in the transcriptional activation of this cardiac muscle gene in ventricular muscle cells. The protein complex that occupies this site is capable of binding to HF-1a and PRE B sites which are known to be required for cardiac muscle-specific expression of rat MLC-2v and alpha-myosin heavy-chain genes, respectively. This study provides direct evidence that USF, a member of the basic helix-loop-helix leucine zipper family, binds to MLE1, HF-1a, and PRE B sites and suggests that it is a component of protein complexes that may coordinately control the expression of MLC-2v and alpha-myosin heavy-chain genes. The current study also provides evidence that USF can positively and negatively regulate the MLC-2v gene via independent cis regulatory elements. Images PMID:7935447

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

    PubMed Central

    2012-01-01

    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 Figα 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

  16. The poplar basic helix-loop-helix transcription factor BEE3 – Like gene affects biomass production by enhancing proliferation of xylem cells in poplar

    SciTech Connect

    Noh, Seol Ah Choi, Young-Im Cho, Jin-Seong Lee, Hyoshin

    2015-06-19

    Brassinosteroids (BRs) play important roles in many aspects of plant growth and development, including regulation of vascular cambium activities and cell elongation. BR-induced BEE3 (brassinosteroid enhanced expression 3) is required for a proper BR response. Here, we identified a poplar (Populus alba × Populus glandulosa) BEE3-like gene, PagBEE3L, encoding a putative basic helix-loop-helix (bHLH)-type transcription factor. Expression of PagBEE3L was induced by brassinolide (BL). Transcripts of PagBEE3L were mainly detected in stems, with the internode having a low level of transcription and the node having a relatively higher level. The function of the PagBEE3L gene was investigated through phenotypic analyses with PagBEE3L-overexpressing (ox) transgenic lines. This work particularly focused on a potential role of PagBEE3L in stem growth and development of polar. The PagBEE3L-ox poplar showed thicker and longer stems than wild-type plants. The xylem cells from the stems of PagBEE3L-ox plants revealed remarkably enhanced proliferation, resulting in an earlier thickening growth than wild-type plants. Therefore, this work suggests that xylem development of poplar is accelerated in PagBEE3L-ox plants and PagBEE3L plays a role in stem growth by increasing the proliferation of xylem cells to promote the initial thickening growth of poplar stems. - Highlights: • We identify the BEE3-like gene form hybrid poplar (Populus alba × Populus glandulosa). • We examine effects of overexpression of PagBEE3L on growth in poplar. • We found that 35S:BEE3L transgenic plants showed more rapid growth than wild-type plants. • BEE3L protein plays an important role in the development of plant stem.

  17. Basic helix loop helix (bHLH) transcription factor 3 (TCF3, E2A) is regulated by androgens in prostate cancer cells

    PubMed Central

    Patel, Divya; Chinaranagari, Swathi; Chaudhary, Jaideep

    2015-01-01

    TCF3 (E2A) is a multifunctional basic helix loop helix (bHLH) transcription factor that is over-expressed in prostate cancer (PCa) as compared to normal prostate and that it acts as a tumor promoter in PCa. Given the diverse biological pathways regulated/influenced by TCF3, little is known about the mechanisms that regulate its expression. TCF3 expression in androgen sensitive LNCaP and insensitive C81 PCa cell lines was determined following treatments with androgen receptor (AR) agonist R1881 and antagonist Casodex. In silico analysis was used to discover putative Androgen Response Elements (ARE) in the TCF3 promoter/intron region. Chromatin Immunoprecipitation (ChIP) with AR antibody and luciferase reporter assays on the above mentioned cell lines was used to confirm AR biding and AR dependent transcriptional activity respectively. The results were confirmed by demonstrating TCF3 expression in LNCaP PCa xenograft models. The results suggested that TCF3 transcript increased in response to R1881 in LNCaP cells but was constitutively expressed in C-81 cell lines. The promoter/Intron region of the TCF3 gene was predicted to contain two putative ARE sites ARE1 and ARE2. ChIP after treatment of LNCaP and C81 cells with R1881 and Casodex showed that the ARE1 and ARE2 were bound by AR in LNCaP cells only in the presence of R1881, whereas C81 cells showed constitutive AR binding. Similar results were observed in luciferase reporter assays indicating that TCF3 is activated by AR in LNCaP cell lines whereas it is independent of androgens in C81 cell line. Luciferase reporter assays also confirmed that ARE1 alone drives androgen dependent transcription. TCF3 expression was only observed in castration resistant LNCaP xenografts in castrated mice. In conclusion, we demonstrate that in PCa androgen receptor regulates the expression of TCF3 which is mediated in part via a consensus androgen response element. The shift in TCF3 expression from androgen regulated to androgen independent during prostate cancer progression, together with lack of expression in normal prostate may provide mechanistic basis underlying the transition of androgen receptor from a tumor suppressor to an oncogene in prostate cancer. PMID:26807321

  18. 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

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

    2013-01-01

    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

  19. A Composite Element that Binds Basic Helix Loop Helix and Basic Leucine Zipper Transcription Factors Is Important for Gonadotropin-Releasing Hormone Regulation of the Follicle-Stimulating Hormone β Gene

    PubMed Central

    Ciccone, Nick A.; Lacza, Charlemagne T.; Hou, Melody Y.; Gregory, Susan J.; Kam, Kyung-Yoon; Xu, Shuyun; Kaiser, Ursula B.

    2008-01-01

    Although FSH plays an essential role in controlling gametogenesis, the biology of FSHβ transcription remains poorly understood, but is known to involve the complex interplay of multiple endocrine factors including GnRH. We have identified a GnRH-responsive element within the rat FSHβ promoter containing an E-box and partial cAMP response element site that are bound by the basic helix loop helix transcription factor family members, upstream stimulating factor (USF)-1/USF-2, and the basic leucine zipper member, cAMP response element-binding protein (CREB), respectively. Expression studies with CREB, USF-1/USF-2, and activating protein-1 demonstrated that the USF transcription factors increased basal transcription, an effect not observed if the cognate binding site was mutated. Conversely, expression of a dominant negative CREB mutant or CREB knockdown attenuated induction by GnRH, whereas dominant negative Fos or USF had no effect on the GnRH response. GnRH stimulation specifically induced an increase in phosphorylated CREB occupation of the FSHβ promoter, leading to the recruitment of CREB-binding protein to enhance gene transcription. In conclusion, a composite element bound by both USF and CREB serves to integrate signals for basal and GnRH-stimulated transcription of the rat FSHβ gene. PMID:18550775

  20. 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

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

    2012-01-01

    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

  1. Basic Helix-Loop-Helix Transcription Factor Heterocomplex of Yas1p and Yas2p Regulates Cytochrome P450 Expression in Response to Alkanes in the Yeast Yarrowia lipolytica▿

    PubMed Central

    Endoh-Yamagami, Setsu; Hirakawa, Kiyoshi; Morioka, Daisuke; Fukuda, Ryouichi; Ohta, Akinori

    2007-01-01

    The expression of the ALK1 gene, which encodes cytochrome P450, catalyzing the first step of alkane oxidation in the alkane-assimilating yeast Yarrowia lipolytica, is highly regulated and can be induced by alkanes. Previously, we identified a cis-acting element (alkane-responsive element 1 [ARE1]) in the ALK1 promoter. We showed that a basic helix-loop-helix (bHLH) protein, Yas1p, binds to ARE1 in vivo and mediates alkane-dependent transcription induction. Yas1p, however, does not bind to ARE1 by itself in vitro, suggesting that Yas1p requires another bHLH protein partner for its DNA binding, as many bHLH transcription factors function by forming heterodimers. To identify such a binding partner of Yas1p, here we screened open reading frames encoding proteins with the bHLH motif from the Y. lipolytica genome database and identified the YAS2 gene. The deletion of the YAS2 gene abolished the alkane-responsive induction of ALK1 transcription and the growth of the yeast on alkanes. We revealed that Yas2p has transactivation activity. Furthermore, Yas1p and Yas2p formed a protein complex that was required for the binding of these proteins to ARE1. These findings allow us to postulate a model in which bHLH transcription factors Yas1p and Yas2p form a heterocomplex and mediate the transcription induction in response to alkanes. PMID:17322346

  2. A Basic Helix-Loop-Helix Transcription Factor, PtrbHLH, of Poncirus trifoliata Confers Cold Tolerance and Modulates Peroxidase-Mediated Scavenging of Hydrogen Peroxide1[C][W

    PubMed Central

    Huang, Xiao-San; Wang, Wei; Zhang, Qian; Liu, Ji-Hong

    2013-01-01

    The basic helix-loop-helix (bHLH) transcription factors are involved in a variety of physiological processes. However, plant bHLHs functioning in cold tolerance and the underlying mechanisms remain poorly understood. Here, we report the identification and functional characterization of PtrbHLH isolated from trifoliate orange (Poncirus trifoliata). The transcript levels of PtrbHLH were up-regulated under various abiotic stresses, particularly cold. PtrbHLH was localized in the nucleus with transactivation activity. Overexpression of PtrbHLH in tobacco (Nicotiana tabacum) or lemon (Citrus limon) conferred enhanced tolerance to cold under chilling or freezing temperatures, whereas down-regulation of PtrbHLH in trifoliate orange by RNA interference (RNAi) resulted in elevated cold sensitivity. A range of stress-responsive genes was up-regulated or down-regulated in the transgenic lemon. Of special note, several peroxidase (POD) genes were induced after cold treatment. Compared with the wild type, POD activity was increased in the overexpression plants but decreased in the RNAi plants, which was inversely correlated with the hydrogen peroxide (H2O2) levels in the tested lines. Treatment of the transgenic tobacco plants with POD inhibitors elevated the H2O2 levels and greatly compromised their cold tolerance, while exogenous replenishment of POD enhanced cold tolerance of the RNAi line. In addition, transgenic tobacco and lemon plants were more tolerant to oxidative stresses. Yeast one-hybrid assay and transient expression analysis demonstrated that PtrbHLH could bind to the E-box elements in the promoter region of a POD gene. Taken together, these results demonstrate that PtrbHLH plays an important role in cold tolerance, at least in part, by positively regulating POD-mediated reactive oxygen species removal. PMID:23624854

  3. Backbone dynamics of a symmetric calmodulin dimer in complex with the calmodulin-binding domain of the basic-helix-loop-helix transcription factor SEF2-1/E2-2: a highly dynamic complex.

    PubMed

    Larsson, Göran; Schleucher, Jürgen; Onions, Jacqueline; Hermann, Stefan; Grundström, Thomas; Wijmenga, Sybren S

    2005-08-01

    Calmodulin (CaM) interacts specifically as a dimer with some dimeric basic-Helix-Loop-Helix (bHLH) transcription factors via a novel high affinity binding mode. Here we report a study of the backbone dynamics by (15)N-spin relaxation on the CaM dimer in complex with a dimeric peptide that mimics the CaM binding region of the bHLH transcription factor SEF2-1. The relaxation data were measured at multiple magnetic fields, and analyzed in a model-free manner using in-house written software designed to detect nanosecond internal motion. Besides picosecond motions, all residues also experience internal motion with an effective correlation time of approximately 2.5 ns with squared order parameter (S(2)) of approximately 0.75. Hydrodynamic calculations suggest that this can be attributed to motions of the N- and C-terminal domains of the CaM dimer in the complex. Moreover, residues with significant exchange broadening are found. They are clustered in the CaM:SEF2-1mp binding interface, the CaM:CaM dimer interface, and in the flexible helix connecting the CaM N- and C-terminal domains, and have similar exchange times (approximately 50 micros), suggesting a cooperative mechanism probably caused by protein:protein interactions. The dynamic features presented here support the conclusion that the conformationally heterogeneous bHLH mimicking peptide trapped inside the CaM dimer exchanges between different binding sites on both nanosecond and microsecond timescales. Nature has thus found a way to specifically recognize a relatively ill-fitting target. This novel mode of target-specific binding, which neither belongs to lock-and-key nor induced-fit binding, is characterized by dimerization and continuous exchange between multiple flexible binding alternatives. PMID:15894636

  4. A Single Amino Acid Substitution in IIIf Subfamily of Basic Helix-Loop-Helix Transcription Factor AtMYC1 Leads to Trichome and Root Hair Patterning Defects by Abolishing Its Interaction with Partner Proteins in Arabidopsis*

    PubMed Central

    Zhao, Hongtao; Wang, Xiaoxue; Zhu, Dandan; Cui, Sujuan; Li, Xia; Cao, Ying; Ma, Ligeng

    2012-01-01

    Plant trichomes and root hairs are powerful models for the study of cell fate determination. In Arabidopsis thaliana, trichome and root hair initiation requires a combination of three groups of proteins, including the WD40 repeat protein TRANSPARENT TESTA GLABRA1 (TTG1), R2R3 repeat MYB protein GLABRA1 (GL1), or WEREWOLF (WER) and the IIIf subfamily of basic helix-loop-helix (bHLH) protein GLABRA3 (GL3) or ENHANCER OF GLABRA3 (EGL3). The bHLH component acts as a docking site for TTG1 and MYB proteins. Here, we isolated a mutant showing defects in trichome and root hair patterning that carried a point mutation (R173H) in AtMYC1 that encodes the fourth member of IIIf bHLH family protein. Genetic analysis revealed partial redundant yet distinct function between AtMYC1 and GL3/EGL3. GLABRA2 (GL2), an important transcription factor involved in trichome and root hair control, was down-regulated in Atmyc1 plants, suggesting the requirement of AtMYC1 for appropriate GL2 transcription. Like its homologs, AtMYC1 formed a complex with TTG1 and MYB proteins but did not dimerized. In addition, the interaction of AtMYC1 with MYB proteins and TTG1 was abrogated by the R173H substitution in Atmyc1-1. We found that this amino acid (Arg) is conserved in the AtMYC1 homologs GL3/EGL3 and that it is essential for their interaction with MYB proteins and for their proper functions. Our findings indicate that AtMYC1 is an important regulator of trichome and root hair initiation, and they reveal a novel amino acid necessary for protein-protein interactions and gene function in IIIf subfamily bHLH transcription factors. PMID:22334670

  5. 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

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

    2012-10-15

    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.

  6. 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

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

    2014-01-01

    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

  7. E Proteins and ID Proteins: Helix-Loop-Helix Partners in Development and Disease.

    PubMed

    Wang, Lan-Hsin; Baker, Nicholas E

    2015-11-01

    The basic Helix-Loop-Helix (bHLH) proteins represent a well-known class of transcriptional regulators. Many bHLH proteins act as heterodimers with members of a class of ubiquitous partners, the E proteins. A widely expressed class of inhibitory heterodimer partners-the Inhibitor of DNA-binding (ID) proteins-also exists. Genetic and molecular analyses in humans and in knockout mice implicate E proteins and ID proteins in a wide variety of diseases, belying the notion that they are non-specific partner proteins. Here, we explore relationships of E proteins and ID proteins to a variety of disease processes and highlight gaps in knowledge of disease mechanisms. PMID:26555048

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

    SciTech Connect

    Desprez, P.; Hara, E.; Bissell, M.J.

    1995-06-01

    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.

  9. Regulation of the proneural gene achaete by helix-loop-helix proteins.

    PubMed Central

    Martínez, C; Modolell, J; Garrell, J

    1993-01-01

    The Achaete (Ac) protein, a transcriptional regulator of the basic-helix-loop-helix (bHLH) type, confers upon ectodermal cells the ability to become neural precursors. Its temporally and spatially regulated expression, together with that of the related Scute (Sc) protein, helps define the pattern of Drosophila melanogaster sensory organs. We have examined the transcriptional control of the ac gene and shown, using in vivo assays, that several E-boxes, putative interacting sites for bHLH proteins, present in the ac promoter are most important for ac regulation. They most likely mediate ac self-stimulation and sc trans-activation. We also demonstrate that ac transcription is negatively regulated in vivo by the gene extramacrochaetae (emc) in a manner dependent on Ac and Sc products. emc encodes an HLH protein that lacks the basic region and presumably antagonizes Ac and Sc function by sequestering these proteins in complexes unable to interact with DNA. Our results strongly support the model of negative regulation of emc on ac and sc transcription through titration of their products. As currently thought, this seems accomplished by heterodimerization via the HLH domain, because an amino acid substitution in this region abolishes the emc antagonistic effect both in vitro and in vivo. Images PMID:8497266

  10. Salvador-Warts-Hippo pathway in a developmental checkpoint monitoring Helix-Loop-Helix proteins

    PubMed Central

    Wang, Lan-Hsin; Baker, Nicholas E.

    2014-01-01

    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

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

    PubMed Central

    Desprez, P Y; Hara, E; Bissell, M J; Campisi, J

    1995-01-01

    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). We 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 arrested growth and formed three-dimensional structures similar to those of control cells. Id-1-expressing cells did not, however, express beta-casein. Moreover, 8 to 10 days after receiving 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. We 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. PMID:7760836

  12. Characterization of a helix-loop-helix (EF hand) motif of silver hake parvalbumin isoform B.

    PubMed Central

    Revett, S. P.; King, G.; Shabanowitz, J.; Hunt, D. F.; Hartman, K. L.; Laue, T. M.; Nelson, D. J.

    1997-01-01

    Parvalbumins are a class of calcium-binding proteins characterized by the presence of several helix-loop-helix (EF-hand) motifs. It is suspected that these proteins evolved via intragene duplication from a single EF-hand. Silver hake parvalbumin (SHPV) consists of three EF-type helix-loop-helix regions, two of which have the ability to bind calcium. The three helix-loop-helix motifs are designated AB, CD, and EF, respectively. In this study, native silver hake parvalbumin isoform B (SHPV-B) has been sequenced by mass spectrometry. The sequence indicates that this parvalbumin is a beta-lineage parvalbumin. SHPV-B was cleaved into two major fragments, consisting of the ABCD and EF regions of the native protein. The 33-amino acid EF fragment (residues 76-108), containing one of the calcium ion binding sites in native SHPV-B, has been isolated and studied for its structural characteristics, ability to bind divalent and trivalent cations, and for its propensity to undergo metal ion-induced self-association. The presence of Ca2+ does not induce significant secondary structure in the EF fragment. However, NMR and CD results indicate significant secondary structure promotion in the EF fragment in the presence of the higher charge-density trivalent cations. Sedimentation equilibrium analysis results show that the EF fragment exists in a monomer-dimer equilibrium when complexed with La3+. PMID:9385642

  13. CHUK, a conserved helix-loop-helix ubiquitous kinase, maps to human chromosome 10 and mouse chromosome 19

    SciTech Connect

    Mock, B.A.; McBride, O.W.; Kozak, C.A.

    1995-05-20

    Helix-loop-helix proteins contain stretches of DNA that encode two amphipathic {alpha}-helices joined by a loop structure and are involved in protein dimerization and transcriptional regulation essential to a variety of cellular processes. CHUK, a newly described conserved helix-loop-helix ubiquitous kinase, was mapped by somatic cell hybrid analyses to human Chr 10q24-q25. Chuk and a related sequence, Chuk-rs1, were mapped to mouse chromosomes 19 and 16, respectively, by a combination of somatic cell hybrid, recombinant inbred, and backcross analyses. 17 refs., 2 figs., 1 tab.

  14. Recognition and Binding of a Helix-Loop-Helix Peptide to Carbonic Anhydrase Occurs via Partly Folded Intermediate Structures

    PubMed Central

    Lignell, Martin; Becker, Hans-Christian

    2010-01-01

    Abstract We have studied the association of a helix-loop-helix peptide scaffold carrying a benzenesulfonamide ligand to carbonic anhydrase using steady-state and time-resolved fluorescence spectroscopy. The helix-loop-helix peptide, developed for biosensing applications, is labeled with the fluorescent probe dansyl, which serves as a polarity-sensitive reporter of the binding event. Using maximum entropy analysis of the fluorescence lifetime of dansyl at 1:1 stoichiometry reveals three characteristic fluorescence lifetime groups, interpreted as differently interacting peptide/protein structures. We characterize these peptide/protein complexes as mostly bound but unfolded, bound and partly folded, and strongly bound and folded. Furthermore, analysis of the fluorescence anisotropy decay resulted in three different dansyl rotational correlation times, namely 0.18, 1.2, and 23 ns. Using the amplitudes of these times, we can correlate the lifetime groups with the corresponding fluorescence anisotropy component. The 23-ns rotational correlation time, which appears with the same amplitude as a 17-ns fluorescence lifetime, shows that the dansyl fluorophore follows the rotational diffusion of carbonic anhydrase when it is a part of the folded peptide/protein complex. A partly folded and partly hydrated interfacial structure is manifested in an 8-ns dansyl fluorescence lifetime and a 1.2-ns rotational correlation time. This structure, we believe, is similar to a molten-globule-like interfacial structure, which allows segmental movement and has a higher degree of solvent exposure of dansyl. Indirect excitation of dansyl on the helix-loop-helix peptide through Förster energy transfer from one or several tryptophans in the carbonic anhydrase shows that the helix-loop-helix scaffold binds to a tryptophan-rich domain of the carbonic anhydrase. We conclude that binding of the peptide to carbonic anhydrase involves a transition from a disordered to an ordered structure of the helix-loop-helix scaffold. PMID:20141756

  15. Recognition and binding of a helix-loop-helix peptide to carbonic anhydrase occurs via partly folded intermediate structures.

    PubMed

    Lignell, Martin; Becker, Hans-Christian

    2010-02-01

    We have studied the association of a helix-loop-helix peptide scaffold carrying a benzenesulfonamide ligand to carbonic anhydrase using steady-state and time-resolved fluorescence spectroscopy. The helix-loop-helix peptide, developed for biosensing applications, is labeled with the fluorescent probe dansyl, which serves as a polarity-sensitive reporter of the binding event. Using maximum entropy analysis of the fluorescence lifetime of dansyl at 1:1 stoichiometry reveals three characteristic fluorescence lifetime groups, interpreted as differently interacting peptide/protein structures. We characterize these peptide/protein complexes as mostly bound but unfolded, bound and partly folded, and strongly bound and folded. Furthermore, analysis of the fluorescence anisotropy decay resulted in three different dansyl rotational correlation times, namely 0.18, 1.2, and 23 ns. Using the amplitudes of these times, we can correlate the lifetime groups with the corresponding fluorescence anisotropy component. The 23-ns rotational correlation time, which appears with the same amplitude as a 17-ns fluorescence lifetime, shows that the dansyl fluorophore follows the rotational diffusion of carbonic anhydrase when it is a part of the folded peptide/protein complex. A partly folded and partly hydrated interfacial structure is manifested in an 8-ns dansyl fluorescence lifetime and a 1.2-ns rotational correlation time. This structure, we believe, is similar to a molten-globule-like interfacial structure, which allows segmental movement and has a higher degree of solvent exposure of dansyl. Indirect excitation of dansyl on the helix-loop-helix peptide through Förster energy transfer from one or several tryptophans in the carbonic anhydrase shows that the helix-loop-helix scaffold binds to a tryptophan-rich domain of the carbonic anhydrase. We conclude that binding of the peptide to carbonic anhydrase involves a transition from a disordered to an ordered structure of the helix-loop-helix scaffold. PMID:20141756

  16. Double-stranded DNA templates can induce alpha-helical conformation in peptides containing lysine and alanine: functional implications for leucine zipper and helix-loop-helix transcription factors.

    PubMed Central

    Johnson, N P; Lindstrom, J; Baase, W A; von Hippel, P H

    1994-01-01

    Transcription factors of the basic-leucine zipper and basic-helix-loop-helix families specifically recognize DNA by means of intrinsically flexible peptide domains that assume an alpha-helical conformation upon binding to target DNA sequences. We have investigated the nonspecific interactions that underlie specific DNA recognition. Circular dichroism measurements showed that 20-bp double-stranded DNA oligonucleotides can act as templates to promote random coil-->alpha-helix transitions in short peptides containing alanine and lysine. This conformational change takes place without altering the structure of the DNA, and neither specific peptide-DNA contacts nor cooperative interactions between peptides are necessary. The conformational change does require (i) double-stranded (but not single-stranded) oligodeoxynucleotides in either the B or the B' conformation and (ii) peptides that can form positively charged amphipathic alpha-helices. In 10 mM Na2HPO4 (pH 7.5; 10 degrees C), the excess free-energy contribution of the DNA template to the stability of the alpha-helical form of the oligopeptides tested was delta Gex = -0.15 (+/- 0.07) kcal/mol per lysine residue. The implications of these results for the thermodynamics and kinetics of DNA target site selection by basic-leucine zipper and basic-helix-loop-helix regulatory proteins are discussed. PMID:8197144

  17. Mutually exclusive expression of a helix-loop-helix gene and N-myc in human neuroblastomas and in normal development.

    PubMed Central

    Ellmeier, W; Aguzzi, A; Kleiner, E; Kurzbauer, R; Weith, A

    1992-01-01

    We have isolated a novel human gene encoding a helix-loop-helix (HLH) protein by molecularly cloning chromosome 1p36-specific CpG islands. The gene termed heir-1 was localized to the neuroblastoma consensus deletion at 1p36.2-p36.12. Its predicted protein is 95.8% identical to the mouse HLH462 protein and has clear homology to the mouse Id and Drosophila emc proteins. Heir-1 does not encode a basic DNA binding domain as found in basic HLH proteins. The gene is expressed specifically at high abundance in adult lung, kidney and adrenal medulla, but not in adult brain. Despite prominent heir-1 expression in adrenal medulla, which is a prime target for neuroblastomas, 10 out of 12 neuroblastoma-derived cell lines revealed very low levels of heir-1 mRNA. Low heir-1 expression was generally found in tumor cell lines with N-myc overexpression, whereas the two cell lines displaying high heir-1 levels did not overexpress N-myc. Mutually exclusive expression of both genes was also found by in situ hybridization in developing mouse tissues, particularly in the forebrain neuroectoderm. We conclude that heir-1 expression is reduced specifically in the majority of neuroblastomas and suggest an inverse correlation between heir-1 and N-myc expression in neuroblastoma tumors and in embryonic development. Images PMID:1628620

  18. A classification of basic helix-loop-helix transcription factors of soybean.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The complete genome sequence of soybean allows unprecedented opportunity for gene discovery. In particular, it is important to determine the potential function or functions of the regulatory genes discovered by interpreting the whole genome sequence. Regulatory genes such as transcription factors ca...

  19. The basic helix-loop-helix transcription factor family in the sacred lotus, Nelumbo nucifera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nelumbo nucifera (Sacred Lotus) is a basal eudicot with exceptional physiological and metabolic properties including seed longevity, adaptations for an aquatic habit, and floral thermiogenesis. It also occupies a unique position in the phylogeny of land plants and can be a useful species for studies...

  20. The Enhancer of split [E(spl)] locus of Drosophila encodes seven independent helix-loop-helix proteins.

    PubMed Central

    Delidakis, C; Artavanis-Tsakonas, S

    1992-01-01

    The E(spl) locus is thought to participate in a cell interaction mechanism that controls the choice of many cell fates during Drosophila development, including the segregation of neural precursors. Previous studies have demonstrated that E(spl) is defined by two groups of closely related transcripts, (i) a cluster of three transcripts encoding proteins bearing a helix-loop-helix (HLH) motif and (ii) a single-copy gene encoding a nuclear protein containing repeated motifs first identified in the beta subunit of guanine nucleotide-binding proteins. Both groups interact genetically with the Notch locus, which codes for a transmembrane protein. We report the structure of four additional HLH-encoding genes that reside in the E(spl) complex and provide evidence that we have now identified all the remaining members of the E(spl) HLH cluster. Images PMID:1528887

  1. Contribution of the helix-loop-helix factor Id2 to regulation of vascular smooth muscle cell proliferation.

    PubMed

    Matsumura, Martin E; Lobe, David R; McNamara, Coleen A

    2002-03-01

    Smooth muscle cell (SMC) proliferation plays a key role in vascular proliferative disorders. The molecular mechanisms that control cell cycle entry of SMCs in response to vascular injury are not well understood. Id2 (inhibitor of DNA binding) is a member of the helix-loop-helix (HLH) family of transcription regulators that are known to promote cell cycle progression. Thus, we investigated the role of Id2 in SMC growth and cell cycle regulation. The results demonstrated that overexpression of Id2 resulted in a significant enhancement of SMC growth via increased S-phase entry. A possible mechanism of Id2-enhanced SMC growth is via regulation of p21 expression, as overexpression of Id2-inhibited transcriptional activity of a 2.3-kb p21 promoter/luciferase reporter construct as well as p21 protein levels. Id2 enhancement of SMC growth and inhibition of p21 expression were dependent on phosphorylation of Id2 by cyclin E/cdk2, as an Id2 cDNA containing a mutation in the cdk2 phosphorylation site (serine 5) failed to regulate SMC cell cycle progression or p21 promoter activity. The mechanism of cyclin E/cdk2 control of the Id2 effect may in part involve regulation of nuclear transport; unlike wild-type Id2, the Id2 mutant was not transported to the nucleus. Finally, in a rat carotid model of arterial injury, Id2 was expressed in a temporal pattern that parallels the kinetics of cellular proliferation. In summary, these results provide evidence that the Id2 protein is integrated into the cell cycle regulatory cascade that results in SMC proliferation following vascular injury and suggest that this effect is at least in part via a cdk2-dependent inhibition of p21 gene expression. PMID:11706002

  2. Cyclic AMP-dependent protein kinase inhibits the activity of myogenic helix-loop-helix proteins.

    PubMed Central

    Li, L; Heller-Harrison, R; Czech, M; Olson, E N

    1992-01-01

    Differentiation of skeletal muscle cells is inhibited by the cyclic AMP (cAMP) signal transduction pathway. Here we report that the catalytic subunit of cAMP-dependent protein kinase (PKA) can substitute for cAMP and suppress muscle-specific transcription by silencing the activity of the MyoD family of regulatory factors, which includes MyoD, myogenin, myf5, and MRF4. Repression by the PKA catalytic (C) subunit is directed at the consensus sequence CANNTG, the target for DNA binding and transcriptional activation by these myogenic regulators. Phosphopeptide mapping of myogenin in vitro and in vivo revealed two PKA phosphorylation sites, both within the basic region. However, repression of myogenin function by PKA does not require direct phosphorylation of these sites but instead involves an indirect mechanism with one or more intermediate steps. Regulation of the transcriptional activity of the MyoD family by modulation of the cAMP signaling pathway may account for the inhibitory effects of certain peptide growth factors on muscle-specific gene expression and may also determine the responsiveness of different cell types to myogenic conversion by these myogenic regulators. Images PMID:1328856

  3. Protein conformational changes studied by diffusion NMR spectroscopy: application to helix-loop-helix calcium binding proteins.

    PubMed

    Weljie, Aalim M; Yamniuk, Aaron P; Yoshino, Hidenori; Izumi, Yoshinobu; Vogel, Hans J

    2003-02-01

    Pulsed-field gradient (PFG) diffusion NMR spectroscopy studies were conducted with several helix-loop-helix regulatory Ca(2+)-binding proteins to characterize the conformational changes associated with Ca(2+)-saturation and/or binding targets. The calmodulin (CaM) system was used as a basis for evaluation, with similar hydrodynamic radii (R(h)) obtained for apo- and Ca(2+)-CaM, consistent with previously reported R(h) data. In addition, conformational changes associated with CaM binding to target peptides from myosin light chain kinase (MLCK), phosphodiesterase (PDE), and simian immunodeficiency virus (SIV) were accurately determined compared with small-angle X-ray scattering results. Both sets of data demonstrate the well-established collapse of the extended Ca(2+)-CaM molecule into a globular complex upon peptide binding. The R(h) of CaM complexes with target peptides from CaM-dependent protein kinase I (CaMKI) and an N-terminal portion of the SIV peptide (SIV-N), as well as the anticancer drug cisplatin were also determined. The CaMKI complex demonstrates a collapse analogous to that observed for MLCK, PDE, and SIV, while the SIV-N shows only a partial collapse. Interestingly, the covalent CaM-cisplatin complex shows a near complete collapse, not expected from previous studies. The method was extended to related calcium binding proteins to show that the R(h) of calcium and integrin binding protein (CIB), calbrain, and the calcium-binding region from soybean calcium-dependent protein kinase (CDPK) decrease on Ca(2+)-binding to various extents. Heteronuclear NMR spectroscopy suggests that for CIB and calbrain this is likely because of shifting the equilibrium from unfolded to folded conformations, with calbrain forming a dimer structure. These results demonstrate the utility of PFG-diffusion NMR to rapidly and accurately screen for molecular size changes on protein-ligand and protein-protein interactions for this class of proteins. PMID:12538886

  4. Basic Helix-Loop-Helix Transcription Factor Twist1 Inhibits Transactivator Function of Master Chondrogenic Regulator Sox9*

    PubMed Central

    Gu, Shoujun; Boyer, Thomas G.; Naski, Michael C.

    2012-01-01

    Canonical Wnt signaling strongly inhibits chondrogenesis. Previously, we identified Twist1 as a critical downstream mediator of Wnt in repression of chondrocyte differentiation. However, the mechanistic basis for the antichondrogenic activity of Twist1 has not heretofore been established. Here, we show that Twist1 suppresses cartilage development by directly inhibiting the transcriptional activity of Sox9, the master regulator of chondrogenesis. Twist1, through its carboxyl-terminal Twist-box, binds to the Sox9 high mobility group DNA-binding domain, inhibiting Sox9 transactivation potential. In chondrocyte precursor cells, Twist1, in a Twist-box-dependent manner, inhibits Sox9-dependent activation of chondrocyte marker gene expression by blocking Sox9-enhancer DNA association. These findings identify Twist1 as an inhibitor of Sox9 and further suggest that the balance between Twist1 and Sox9 may determine the earliest steps of chondrogenesis. PMID:22532563

  5. 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

    Villano, C.M.; White, L.A. . E-mail: lawhite@aesop.rutgers.edu

    2006-08-01

    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.

  6. Reovirus FAST Proteins Drive Pore Formation and Syncytiogenesis Using a Novel Helix-Loop-Helix Fusion-Inducing Lipid Packing Sensor

    PubMed Central

    Sarker, Muzaddid; de Antueno, Roberto; Langelaan, David N.; Parmar, Hiren B.; Shin, Kyungsoo; Rainey, Jan K.; Duncan, Roy

    2015-01-01

    Pore formation is the most energy-demanding step during virus-induced membrane fusion, where high curvature of the fusion pore rim increases the spacing between lipid headgroups, exposing the hydrophobic interior of the membrane to water. How protein fusogens breach this thermodynamic barrier to pore formation is unclear. We identified a novel fusion-inducing lipid packing sensor (FLiPS) in the cytosolic endodomain of the baboon reovirus p15 fusion-associated small transmembrane (FAST) protein that is essential for pore formation during cell-cell fusion and syncytiogenesis. NMR spectroscopy and mutational studies indicate the dependence of this FLiPS on a hydrophobic helix-loop-helix structure. Biochemical and biophysical assays reveal the p15 FLiPS preferentially partitions into membranes with high positive curvature, and this partitioning is impeded by bis-ANS, a small molecule that inserts into hydrophobic defects in membranes. Most notably, the p15 FLiPS can be functionally replaced by heterologous amphipathic lipid packing sensors (ALPS) but not by other membrane-interactive amphipathic helices. Furthermore, a previously unrecognized amphipathic helix in the cytosolic domain of the reptilian reovirus p14 FAST protein can functionally replace the p15 FLiPS, and is itself replaceable by a heterologous ALPS motif. Anchored near the cytoplasmic leaflet by the FAST protein transmembrane domain, the FLiPS is perfectly positioned to insert into hydrophobic defects that begin to appear in the highly curved rim of nascent fusion pores, thereby lowering the energy barrier to stable pore formation. PMID:26061049

  7. Amino-terminal domains of c-myc and N-myc proteins mediate binding to the retinoblastoma gene product

    NASA Astrophysics Data System (ADS)

    Rustgi, Anil K.; Dyson, Nicholas; Bernards, Rene

    1991-08-01

    THE proteins encoded by the myc gene family are involved in the control of cell proliferation and differentiation, and aberrant expression of myc proteins has been implicated in the genesis of a variety of neoplasms1. In the carboxyl terminus, myc proteins have two domains that encode a basic domain/helix-loop-helix and a leucine zipper motif, respectively. These motifs are involved both in DNA binding and in protein dimerization2-5. In addition, myc protein family members share several regions of highly conserved amino acids in their amino termini that are essential for transformation6,7. We report here that an N-terminal domain present in both the c-myc and N-myc proteins mediates binding to the retinoblastoma gene product, pRb. We show that the human papilloma virus E7 protein competes with c-myc for binding to pRb, indicating that these proteins share overlapping binding sites on pRb. Furthermore, a mutant Rb protein from a human tumour cell line that carried a 35-amino-acid deletion in its C terminus failed to bind to c-myc. Our results suggest that c-myc and pRb cooperate through direct binding to control cell proliferation.

  8. Overexpression of a citrus basic helix-loop-helix transcription factor (CubHLH1), which is homologous to Arabidopsis activation-tagged bri1 suppressor 1 interacting factor genes, modulates carotenoid metabolism in transgenic tomato.

    PubMed

    Endo, Tomoko; Fujii, Hiroshi; Sugiyama, Aiko; Nakano, Michiharu; Nakajima, Naoko; Ikoma, Yoshinori; Omura, Mitsuo; Shimada, Takehiko

    2016-02-01

    To explore the transcription factors associated with carotenoid metabolism in citrus fruit, one transcription factor (CubHLH1) was selected through microarray screening in Satsuma mandarin (Citrus unshiu Marc.) fruit, which was treated with exogenous ethylene or gibberellin (GA), accelerating or retarding carotenoid accumulation in peel, respectively. The amino acid sequence of CubHLH1 has homology to Arabidopsis activation-tagged bri1 suppressor 1 (ATBS1) interacting factor (AIF), which is functionally characterized as a negative regulator of the brassinolide (BR) signalling pathway. Yeast two-hybrid analysis revealed that protein for CubHLH1 could interact with Arabidopsis and tomato ATBS1. Overexpression of CubHLH1 caused a dwarf phenotype in transgenic tomato (Solanum lycopersicum L.), suggesting that CubHLH1 has a similar function to Arabidopsis AIF. In the transgenic tomato fruit at ripening stage, the lycopene content was reduced along with the changes in carotenoid biosynthetic gene expression. The abscisic acid (ABA) content of all the transgenic tomato fruit was higher than that of the wild type. These results implied that CubHLH1 is considered to have a similar function to Arabidopsis AIFs and might be directly involved in carotenoid metabolism in mature citrus fruit. PMID:26795149

  9. Specificity for the Hairy/enhancer of split basic helix-loop-helix (bHLH) proteins maps outside the bHLH domain and suggests two separable modes of transcriptional repression

    SciTech Connect

    Dawson, S.R.; Turner, D.L.; Weintraub, H.; Parkhurst, S.M.

    1995-12-01

    This report investigates transcriptional repressors in Drosophila melanogaster and their function in and effect on developmental processes such as sex determination. Details on the mechanism of function of these transcriptional repressors are also discussed. 50 refs., 3 figs., 4 tabs.

  10. Functional diversification of the potato R2R3 MYB anthocyanin activators AN1, MYBA1, and MYB113 and their interaction with basic helix-loop-helix cofactors

    PubMed Central

    Liu, Yuhui; Lin-Wang, Kui; Espley, Richard V.; Wang, Li; Yang, Hongyu; Yu, Bin; Dare, Andrew; Varkonyi-Gasic, Erika; Wang, Jing; Zhang, Junlian; Wang, Di; Allan, Andrew C.

    2016-01-01

    In potato (Solanum tuberosum L.), R2R3 MYBs are involved in the regulation of anthocyanin biosynthesis. We examined sequences of these MYBs in cultivated potatoes, which are more complex than diploid potato due to ploidy and heterozygosity. We found amino acid variants in the C-terminus of the MYB StAN1, termed R0, R1, and R3, due to the presence of a repeated 10-amino acid motif. These variant MYBs showed some expression in both white and pigmented tubers. We found several new alleles or gene family members of R2R3 MYBs, StMYBA1 and StMYB113, which were also expressed in white potato tubers. From functional analysis in tobacco, we showed that the presence of a C-terminal 10-amino acid motif is optimal for activating anthocyanin accumulation. Engineering a motif back into a MYB lacking this sequence enhanced its activating ability. Versions of StMYBA1 and StMYB113 can also activate anthocyanin accumulation in tobacco leaves, with the exception of StMYB113-3, which has a partial R2R3 domain. We isolated five family members of potato StbHLH1, and one StJAF13, to test their ability to interact with MYB variants. The results showed that two alleles of StbHLH1 from white skin and red skin are non-functional, while three other StbHLH1s have different co-regulating abilities, and need to be activated by StJAF13. Combined with expression analysis in potato tuber, results suggest that StbHLH1 and StJAF13 are key co-regulators of anthocyanin biosynthesis, while the transcripts of MYB variants StAN1, StMYBA1, and StMYB113 are well expressed, even in the absence of pigmentation. PMID:26884602

  11. 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

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

    2014-01-01

    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

  12. Functional diversification of the potato R2R3 MYB anthocyanin activators AN1, MYBA1, and MYB113 and their interaction with basic helix-loop-helix cofactors.

    PubMed

    Liu, Yuhui; Lin-Wang, Kui; Espley, Richard V; Wang, Li; Yang, Hongyu; Yu, Bin; Dare, Andrew; Varkonyi-Gasic, Erika; Wang, Jing; Zhang, Junlian; Wang, Di; Allan, Andrew C

    2016-04-01

    In potato (Solanum tuberosumL.), R2R3 MYBs are involved in the regulation of anthocyanin biosynthesis. We examined sequences of these MYBs in cultivated potatoes, which are more complex than diploid potato due to ploidy and heterozygosity. We found amino acid variants in the C-terminus of the MYB StAN1, termed R0, R1, and R3, due to the presence of a repeated 10-amino acid motif. These variant MYBs showed some expression in both white and pigmented tubers. We found several new alleles or gene family members of R2R3 MYBs,StMYBA1andStMYB113, which were also expressed in white potato tubers. From functional analysis in tobacco, we showed that the presence of a C-terminal 10-amino acid motif is optimal for activating anthocyanin accumulation. Engineering a motif back into a MYB lacking this sequence enhanced its activating ability. Versions ofStMYBA1andStMYB113can also activate anthocyanin accumulation in tobacco leaves, with the exception ofStMYB113-3, which has a partial R2R3 domain. We isolated five family members of potatoStbHLH1, and oneStJAF13, to test their ability to interact with MYB variants. The results showed that two alleles ofStbHLH1from white skin and red skin are non-functional, while three otherStbHLH1s have different co-regulating abilities, and need to be activated by StJAF13. Combined with expression analysis in potato tuber, results suggest thatStbHLH1andStJAF13are key co-regulators of anthocyanin biosynthesis, while the transcripts of MYB variantsStAN1,StMYBA1, andStMYB113are well expressed, even in the absence of pigmentation. PMID:26884602

  13. The helix-loop-helix protein id1 controls stem cell proliferation during regenerative neurogenesis in the adult zebrafish telencephalon.

    PubMed

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

    2015-03-01

    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, the id1 gene, encoding a negative regulator of E-proteins, was found to be upregulated 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. PMID:25376791

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

    ERIC Educational Resources Information Center

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

    2003-01-01

    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

  15. The Helix-Loop-Helix Protein ID2 Governs NK Cell Fate by Tuning Their Sensitivity to Interleukin-15.

    PubMed

    Delconte, Rebecca B; Shi, Wei; Sathe, Priyanka; Ushiki, Takashi; Seillet, Cyril; Minnich, Martina; Kolesnik, Tatiana B; Rankin, Lucille C; Mielke, Lisa A; Zhang, Jian-Guo; Busslinger, Meinrad; Smyth, Mark J; Hutchinson, Dana S; Nutt, Stephen L; Nicholson, Sandra E; Alexander, Warren S; Corcoran, Lynn M; Vivier, Eric; Belz, Gabrielle T; Carotta, Sebastian; Huntington, Nicholas D

    2016-01-19

    The inhibitor of DNA binding 2 (Id2) is essential for natural killer (NK) cell development with its canonical role being to antagonize E-protein function and alternate lineage fate. Here we have identified a key role for Id2 in regulating interleukin-15 (IL-15) receptor signaling and homeostasis of NK cells by repressing multiple E-protein target genes including Socs3. Id2 deletion in mature NK cells was incompatible with their homeostasis due to impaired IL-15 receptor signaling and metabolic function and this could be rescued by strong IL-15 receptor stimulation or genetic ablation of Socs3. During NK cell maturation, we observed an inverse correlation between E-protein target genes and Id2. These results shift the current paradigm on the role of ID2, indicating that it is required not only to antagonize E-proteins during NK cell commitment, but constantly required to titrate E-protein activity to regulate NK cell fitness and responsiveness to IL-15. PMID:26795246

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

    ERIC Educational Resources Information Center

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

    2003-01-01

    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…

  17. Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes

    PubMed Central

    Marchegiani, Shannon; Davis, Taylor; Tessadori, Federico; van Haaften, Gijs; Brancati, Francesco; Hoischen, Alexander; Huang, Haigen; Valkanas, Elise; Pusey, Barbara; Schanze, Denny; Venselaar, Hanka; Vulto-van Silfhout, Anneke T.; Wolfe, Lynne A.; Tifft, Cynthia J.; Zerfas, Patricia M.; Zambruno, Giovanna; Kariminejad, Ariana; Sabbagh-Kermani, Farahnaz; Lee, Janice; Tsokos, Maria G.; Lee, Chyi-Chia R.; Ferraz, Victor; da Silva, Eduarda Morgana; Stevens, Cathy A.; Roche, Nathalie; Bartsch, Oliver; Farndon, Peter; Bermejo-Sanchez, Eva; Brooks, Brian P.; Maduro, Valerie; Dallapiccola, Bruno; Ramos, Feliciano J.; Chung, Hon-Yin Brian; Le Caignec, Cédric; Martins, Fabiana; Jacyk, Witold K.; Mazzanti, Laura; Brunner, Han G.; Bakkers, Jeroen; Lin, Shuo; Malicdan, May Christine V.; Boerkoel, Cornelius F.; Gahl, William A.; de Vries, Bert B.A.; van Haelst, Mieke M.; Zenker, Martin; Markello, Thomas C.

    2015-01-01

    Ablepharon macrostomia syndrome (AMS) and Barber-Say syndrome (BSS) are rare congenital ectodermal dysplasias characterized by similar clinical features. To establish the genetic basis of AMS and BSS, we performed extensive clinical phenotyping, whole exome and candidate gene sequencing, and functional validations. We identified a recurrent de novo mutation in TWIST2 in seven independent AMS-affected families, as well as another recurrent de novo mutation affecting the same amino acid in ten independent BSS-affected families. Moreover, a genotype-phenotype correlation was observed, because the two syndromes differed based solely upon the nature of the substituting amino acid: a lysine at TWIST2 residue 75 resulted in AMS, whereas a glutamine or alanine yielded BSS. TWIST2 encodes a basic helix-loop-helix transcription factor that regulates the development of mesenchymal tissues. All identified mutations fell in the basic domain of TWIST2 and altered the DNA-binding pattern of Flag-TWIST2 in HeLa cells. Comparison of wild-type and mutant TWIST2 expressed in zebrafish identified abnormal developmental phenotypes and widespread transcriptome changes. Our results suggest that autosomal-dominant TWIST2 mutations cause AMS or BSS by inducing protean effects on the transcription factor’s DNA binding. PMID:26119818

  18. Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes.

    PubMed

    Marchegiani, Shannon; Davis, Taylor; Tessadori, Federico; van Haaften, Gijs; Brancati, Francesco; Hoischen, Alexander; Huang, Haigen; Valkanas, Elise; Pusey, Barbara; Schanze, Denny; Venselaar, Hanka; Vulto-van Silfhout, Anneke T; Wolfe, Lynne A; Tifft, Cynthia J; Zerfas, Patricia M; Zambruno, Giovanna; Kariminejad, Ariana; Sabbagh-Kermani, Farahnaz; Lee, Janice; Tsokos, Maria G; Lee, Chyi-Chia R; Ferraz, Victor; da Silva, Eduarda Morgana; Stevens, Cathy A; Roche, Nathalie; Bartsch, Oliver; Farndon, Peter; Bermejo-Sanchez, Eva; Brooks, Brian P; Maduro, Valerie; Dallapiccola, Bruno; Ramos, Feliciano J; Chung, Hon-Yin Brian; Le Caignec, Cédric; Martins, Fabiana; Jacyk, Witold K; Mazzanti, Laura; Brunner, Han G; Bakkers, Jeroen; Lin, Shuo; Malicdan, May Christine V; Boerkoel, Cornelius F; Gahl, William A; de Vries, Bert B A; van Haelst, Mieke M; Zenker, Martin; Markello, Thomas C

    2015-07-01

    Ablepharon macrostomia syndrome (AMS) and Barber-Say syndrome (BSS) are rare congenital ectodermal dysplasias characterized by similar clinical features. To establish the genetic basis of AMS and BSS, we performed extensive clinical phenotyping, whole exome and candidate gene sequencing, and functional validations. We identified a recurrent de novo mutation in TWIST2 in seven independent AMS-affected families, as well as another recurrent de novo mutation affecting the same amino acid in ten independent BSS-affected families. Moreover, a genotype-phenotype correlation was observed, because the two syndromes differed based solely upon the nature of the substituting amino acid: a lysine at TWIST2 residue 75 resulted in AMS, whereas a glutamine or alanine yielded BSS. TWIST2 encodes a basic helix-loop-helix transcription factor that regulates the development of mesenchymal tissues. All identified mutations fell in the basic domain of TWIST2 and altered the DNA-binding pattern of Flag-TWIST2 in HeLa cells. Comparison of wild-type and mutant TWIST2 expressed in zebrafish identified abnormal developmental phenotypes and widespread transcriptome changes. Our results suggest that autosomal-dominant TWIST2 mutations cause AMS or BSS by inducing protean effects on the transcription factor's DNA binding. PMID:26119818

  19. Protein- mediated enamel mineralization

    PubMed Central

    Moradian-Oldak, Janet

    2012-01-01

    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

  20. A smallest 6 kda metalloprotease, mini-matrilysin, in living world: a revolutionary conserved zinc-dependent proteolytic domain- helix-loop-helix catalytic zinc binding domain (ZBD)

    PubMed Central

    2012-01-01

    Background The Aim of this study is to study the minimum zinc dependent metalloprotease catalytic folding motif, helix B Met loop-helix C, with proteolytic catalytic activities in metzincin super family. The metzincin super family share a catalytic domain consisting of a twisted five-stranded β sheet and three long α helices (A, B and C). The catalytic zinc is at the bottom of the cleft and is ligated by three His residues in the consensus sequence motif, HEXXHXXGXXH, which is located in helix B and part of the adjacent Met turn region. An interesting question is - what is the minimum portion of the enzyme that still possesses catalytic and inhibitor recognition?” Methods We have expressed a 60-residue truncated form of matrilysin which retains only the helix B-Met turn-helix C region and deletes helix A and the five-stranded β sheet which form the upper portion of the active cleft. This is only 1/4 of the full catalytic domain. The E. coli derived 6 kDa MMP-7 ZBD fragments were purified and refolded. The proteolytic activities were analyzed by Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2 peptide assay and CM-transferrin zymography analysis. SC44463, BB94 and Phosphoramidon were computationally docked into the 3day structure of the human MMP7 ZBD and TAD and thermolysin using the docking program GOLD. Results This minimal 6 kDa matrilysin has been refolded and shown to have proteolytic activity in the Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2 peptide assay. Triton X-100 and heparin are important factors in the refolding environment for this mini-enzyme matrilysin. This minienzyme has the proteolytic activity towards peptide substrate, but the hexamer and octamer of the mini MMP-7 complex demonstrates the CM-transferrin proteolytic activities in zymographic analysis. Peptide digestion is inhibited by SC44463, specific MMP7 inhibitors, but not phosphorimadon. Interestingly, the mini MMP-7 can be processed by autolysis and producing ~ 6 ~ 7 kDa fragments. Thus, many of the functions of the enzyme are retained indicating that the helix B-Met loop-helix C is the minimal functional “domain” found to date for the matrixin family. Conclusions The helix B-Met loop-helix C folding conserved in metalloprotease metzincin super family is able to facilitate proteolytic catalysis for specific substrate and inhibitor recognition. The autolysis processing and producing 6 kDa mini MMP-7 is the smallest metalloprotease in living world. PMID:22642296

  1. Coupling of ligand binding and dimerization of helix-loop-helix peptides: spectroscopic and sedimentation analyses of calbindin D9k EF-hands.

    PubMed

    Julenius, Karin; Robblee, James; Thulin, Eva; Finn, Bryan E; Fairman, Robert; Linse, Sara

    2002-05-15

    Isolated Ca2+-binding EF-hand peptides have a tendency to dimerize. This study is an attempt to account for the coupled equilibria of Ca2+-binding and peptide association for two EF-hands with strikingly different loop sequence and net charge. We have studied each of the two separate EF-hand fragments from calbindin D9k. A series of Ca2+-titrations at different peptide concentrations were monitored by CD and fluorescence spectroscopy. All data were fitted simultaneously to both a complete model of all possible equilibrium intermediates and a reduced model not including dimerization in the absence of Ca2+. Analytical ultracentrifugation shows that the peptides may occur as monomers or dimers depending on the solution conditions. Our results show strikingly different behavior for the two EF-hands. The fragment containing the N-terminal EF-hand shows a strong tendency to dimerize in the Ca2+-bound state. The average Ca2+-affinity is 3.5 orders of magnitude lower than for the intact protein. We observe a large apparent cooperativity of Ca2+ binding for the overall process from Ca2+-free monomer to fully loaded dimer, showing that a Ca2+-free EF-hand folds upon dimerization to a Ca2+-bound EF-hand, thereby presenting a preformed binding site to the second Ca2+-ion. The C-terminal EF-hand shows a much smaller tendency to dimerize, which may be related to its larger net negative charge. In spite of the differences in dimerization behavior, the Ca2+ affinities of both EF-hand fragments are similar and in the range lgK = 4.6-5.3. PMID:11948786

  2. The NEUROD gene maps to human chromosome 2q32 and mouse chromosome 2.

    PubMed

    Tamimi, R; Steingrimsson, E; Copeland, N G; Dyer-Montgomery, K; Lee, J E; Hernandez, R; Jenkins, N A; Tapscott, S J

    1996-06-15

    The Neurod gene is a basic-helix-loop-helix gene that regulates neurogenesis and is identical to the hamster beta2 gene that was cloned as a regulator of insulin transcription. Here we report the cloning of human NEUROD and mapping of the gene to human chromosome 2q32 and to mouse chromosome 2. PMID:8786144

  3. Phytochrome Induces Rapid PIF5 Phosphorylation and Degradation in Response to Red-Light Activation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 transcriptio...

  4. Functional profiling identifies genes involved in organ specific branches of the PIF3 regulatory network in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The phytochrome (phy)-interacting basic helix-loop-helix transcription factors (PIFs) constitutively sustain the etiolated state of dark-germinated seedlings by actively repressing deetiolation in darkness. This action is rapidly reversed upon light exposure by phy-induced proteolytic degradation of...

  5. DIRECT TARGETING OF LIGHT SIGNALS TO A PROMOTER ELEMENT-BOUND TRANSCRIPTION FACTOR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Light signals perceived by the phytochrome family of sensory photoreceptors are transduced to photoresponsive genes by an unknown mechanism. Here, we show that the basic helix-loop-helix transcription factor PIF3 binds specifically to a G-box DNA-sequence motif present in various light-regulated gen...

  6. The Arabidopsis Phytochrome-Interacting Factor PIF7, Together with PIF3 and PIF4, Regulates Responses to Prolonged Red Light by Modulating phyB Levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We show that a previously uncharacterized Arabidopsis thaliana basic helix-loop-helix (bHLH) phytochrome interacting factor (PIF), designated PIF7, interacts specifically with the far-red light–absorbing Pfr form of phyB through a conserved domain called the active phyB binding motif. Similar to PIF...

  7. Mechanics of Protein-Mediated DNA Looping

    NASA Astrophysics Data System (ADS)

    Meiners, Jens-Christian

    2009-03-01

    The formation of looped DNA-protein complexes in which a protein or protein assembly binds to multiple distant operator sites on the DNA is a common feature for many regulatory schemes on the transcriptional level. In a living cell, a multitude of mechanical forces and constraints act on these complexes, and it is imperative to understand their effects on biological function. For this aim, we study the lactose repressor as a model system for protein-mediated DNA looping in single-molecule experiments. Using a novel axial constant-force optical trapping scheme that allows us to manipulate sub-micron DNA fragments with well-controlled forces down to the 10 fN range, we show that mechanical tension in the substrate DNA of hundred femtonewton is sufficient to disrupt the loop formation process, which suggests that such mechanical tension may provide a mechanical pathway to controlling gene expression in vivo. From the force sensitivity of the loop formation process, we can also infer the topology of the looped complex; in our case an antiparallel conformation. In addition, we will present new tethered-particle microscopy data that shows lifetimes of the looped complexes that are two to three orders of magnitude shorter than those measured in biochemical competition assays and discuss possible interpretations, including the suggestion that operator binding of the lactose repressor tetramer leads to a destabilization of the dimer-dimer interface and that thus the loop breakdown process is mostly a dissociation of the tetramer into two dimers, instead, as widely assumed, an unbinding of the tetramer from the DNA.

  8. Differences between MyoD DNA binding and activation site requirements revealed by functional random sequence selection.

    PubMed Central

    Huang, J; Blackwell, T K; Kedes, L; Weintraub, H

    1996-01-01

    A method has been developed for selecting functional enhancer/promoter sites from random DNA sequences in higher eukaryotic cells. Of sequences that were thus selected for transcriptional activation by the muscle-specific basic helix-loop-helix protein MyoD, only a subset are similar to the preferred in vitro binding consensus, and in the same promoter context an optimal in vitro binding site was inactive. Other sequences with full transcriptional activity instead exhibit sequence preferences that, remarkably, are generally either identical or very similar to those found in naturally occurring muscle-specific promoters. This first systematic examination of the relation between DNA binding and transcriptional activation by basic helix-loop-helix proteins indicates that binding per se is necessary but not sufficient for transcriptional activation by MyoD and implies a requirement for other DNA sequence-dependent interactions or conformations at its binding site. PMID:8668207

  9. ABC-F Proteins Mediate Antibiotic Resistance through Ribosomal Protection

    PubMed Central

    Sharkey, Liam K. R.; Edwards, Thomas A.

    2016-01-01

    ABSTRACT Members of the ABC-F subfamily of ATP-binding cassette proteins mediate resistance to a broad array of clinically important antibiotic classes that target the ribosome of Gram-positive pathogens. The mechanism by which these proteins act has been a subject of long-standing controversy, with two competing hypotheses each having gained considerable support: antibiotic efflux versus ribosomal protection. Here, we report on studies employing a combination of bacteriological and biochemical techniques to unravel the mechanism of resistance of these proteins, and provide several lines of evidence that together offer clear support to the ribosomal protection hypothesis. Of particular note, we show that addition of purified ABC-F proteins to an in vitro translation assay prompts dose-dependent rescue of translation, and demonstrate that such proteins are capable of displacing antibiotic from the ribosome in vitro. To our knowledge, these experiments constitute the first direct evidence that ABC-F proteins mediate antibiotic resistance through ribosomal protection. PMID:27006457

  10. ABC-F Proteins Mediate Antibiotic Resistance through Ribosomal Protection.

    PubMed

    Sharkey, Liam K R; Edwards, Thomas A; O'Neill, Alex J

    2016-01-01

    Members of the ABC-F subfamily of ATP-binding cassette proteins mediate resistance to a broad array of clinically important antibiotic classes that target the ribosome of Gram-positive pathogens. The mechanism by which these proteins act has been a subject of long-standing controversy, with two competing hypotheses each having gained considerable support: antibiotic efflux versus ribosomal protection. Here, we report on studies employing a combination of bacteriological and biochemical techniques to unravel the mechanism of resistance of these proteins, and provide several lines of evidence that together offer clear support to the ribosomal protection hypothesis. Of particular note, we show that addition of purified ABC-F proteins to anin vitrotranslation assay prompts dose-dependent rescue of translation, and demonstrate that such proteins are capable of displacing antibiotic from the ribosomein vitro To our knowledge, these experiments constitute the first direct evidence that ABC-F proteins mediate antibiotic resistance through ribosomal protection.IMPORTANCEAntimicrobial resistance ranks among the greatest threats currently facing human health. Elucidation of the mechanisms by which microorganisms resist the effect of antibiotics is central to understanding the biology of this phenomenon and has the potential to inform the development of new drugs capable of blocking or circumventing resistance. Members of the ABC-F family, which includelsa(A),msr(A),optr(A), andvga(A), collectively yield resistance to a broader range of clinically significant antibiotic classes than any other family of resistance determinants, although their mechanism of action has been controversial since their discovery 25 years ago. Here we present the first direct evidence that proteins of the ABC-F family act to protect the bacterial ribosome from antibiotic-mediated inhibition. PMID:27006457

  11. Armet is an effector protein mediating aphid-plant interactions.

    PubMed

    Wang, Wei; Dai, Huaien; Zhang, Yi; Chandrasekar, Raman; Luo, Lan; Hiromasa, Yasuaki; Sheng, Changzhong; Peng, Gongxin; Chen, Shaoliang; Tomich, John M; Reese, John; Edwards, Owain; Kang, Le; Reeck, Gerald; Cui, Feng

    2015-05-01

    Aphid saliva is predicted to contain proteins that modulate plant defenses and facilitate feeding. Armet is a well-characterized bifunctional protein in mammalian systems. Here we report a new role of Armet, namely as an effector protein in the pea aphid, Acyrthosiphon pisum. Pea aphid Armet's physical and chemical properties and its intracellular role are comparable to those reported for mammalian Armets. Uniquely, we detected Armet in aphid watery saliva and in the phloem sap of fava beans fed on by aphids. Armet's transcript level is several times higher in the salivary gland when aphids feed on bean plants than when they feed on an artificial diet. Knockdown of the Armet transcript by RNA interference disturbs aphid feeding behavior on fava beans measured by the electrical penetration graph technique and leads to a shortened life span. Inoculation of pea aphid Armet protein into tobacco leaves induced a transcriptional response that included pathogen-responsive genes. The data suggest that Armet is an effector protein mediating aphid-plant interactions. PMID:25678626

  12. Prostacyclin-induced hyperthermia - Implication of a protein mediator

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  13. G protein-mediated inhibition of myosin light-chain phosphatase in vascular smooth muscle.

    PubMed Central

    Kitazawa, T; Masuo, M; Somlyo, A P

    1991-01-01

    The mechanism of G protein-mediated sensitization of the contractile apparatus of smooth muscle to Ca2+ was studied in receptor-coupled alpha-toxin-permeabilized rabbit portal vein smooth muscle. To test the hypothesis that Ca2+ sensitization is due to inhibition of myosin light-chain (MLC) phosphatase activity, we measured the effect of guanosine 5'-[gamma-thio]triphosphate and phenylephrine on the rate of MLC dephosphorylation in muscles preactivated with Ca2+ and incubated in Ca(2+)- and ATP-free solution containing 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-9) to block MLC kinase activity. Guanosine 5'-[gamma-thio]triphosphate alone (300 microM) or in combination (3 microM) with phenylephrine decreased the rates of relaxation and dephosphorylation of MLC to about half of control values; this inhibition is sufficient to account for maximal G protein-mediated Ca2+ sensitization of MLC phosphorylation. The rate of thiophosphorylation of MLC with adenosine 5'-[gamma-thio]-triphosphate was not affected by guanosine 5'-[gamma-thio]triphosphate. We suggest that inhibition of protein phosphatase(s) by G protein(s) may have important regulatory functions. PMID:1656467

  14. FIT, the FER-LIKE IRON DEFICIENCY INDUCED TRANSCRIPTION FACTOR in Arabidopsis.

    PubMed

    Bauer, Petra; Ling, Hong-Qing; Guerinot, Mary Lou

    2007-05-01

    Our groups have previously identified in independent studies the gene At2g28160 as a central transcription factor that is required for up-regulation of iron deficiency responses in Arabidopsis roots. At2g28160 has been named in different ways in our previous studies, namely FRU=FER-LIKE REGULATOR OF IRON UPTAKE [M. Jakoby, H.Y. Wang, W. Reidt, B. Weisshaar, P. Bauer, FRU (BHLH029) is required for induction of iron mobilization genes in Arabidopsis thaliana, FEBS Lett. 577 (2004) 528-534], BHLH029 [M.A. Heim, M. Jakoby, M. Werber, C. Martin, B. Weisshaar, P.C. Bailey, The basic helix-loop-helix transcription factor family in plants: a genome-wide study of protein structure and functional diversity, Mol. Biol. Evol. 20 (2003) 735-747; Y.X. Yuan, J. Zhang, D.W. Wang, H.Q. Ling, AtbHLH29 of Arabidopsis thaliana is a functional ortholog of tomato FER involved in controlling iron acquisition in strategy I plants, Cell Res. 15 (2005) 613-621] or FIT1=Fe-DEFICIENCY-INDUCED TRANSCRIPTION FACTOR1 [E.P.Colangelo, M.L. Guerinot, The essential basic helix-loop-helix protein FIT1 is required for the iron deficiency response, Plant Cell 12 (2004) 3400-3412.] To avoid any confusion in the future we propose a common name for At2g28160 in Arabidopsis, namely FIT=FER-LIKE IRON DEFICIENCY-INDUCED TRANSCRIPTION FACTOR. PMID:17466530

  15. The MYB182 protein down-regulates proanthocyanidin and anthocyanin biosynthesis in poplar by repressing both structural and regulatory flavonoid genes.

    PubMed

    Yoshida, Kazuko; Ma, Dawei; Constabel, C Peter

    2015-03-01

    Trees in the genus Populus (poplar) contain phenolic secondary metabolites including the proanthocyanidins (PAs), which help to adapt these widespread trees to diverse environments. The transcriptional activation of PA biosynthesis in response to herbivory and ultraviolet light stress has been documented in poplar leaves, and a regulator of this process, the R2R3-MYB transcription factor MYB134, has been identified. MYB134-overexpressing transgenic plants show a strong high-PA phenotype. Analysis of these transgenic plants suggested the involvement of additional MYB transcription factors, including repressor-like MYB factors. Here, MYB182, a subgroup 4 MYB factor, was found to act as a negative regulator of the flavonoid pathway. Overexpression of MYB182 in hairy root culture and whole poplar plants led to reduced PA and anthocyanin levels as well as a reduction in the expression of key flavonoid genes. Similarly, a reduced accumulation of transcripts of a MYB PA activator and a basic helix-loop-helix cofactor was observed in MYB182-overexpressing hairy roots. Transient promoter activation assays in poplar cell culture demonstrated that MYB182 can disrupt transcriptional activation by MYB134 and that the basic helix-loop-helix-binding motif of MYB182 was essential for repression. Microarray analysis of transgenic plants demonstrated that down-regulated targets of MYB182 also include shikimate pathway genes. This work shows that MYB182 plays an important role in the fine-tuning of MYB134-mediated flavonoid metabolism. PMID:25624398

  16. A juvenile hormone transcription factor Bmdimm-fibroin H chain pathway is involved in the synthesis of silk protein in silkworm, Bombyx mori.

    PubMed

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

    2015-01-01

    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

  17. SPATULA, a gene that controls development of carpel margin tissues in Arabidopsis, encodes a bHLH protein.

    PubMed

    Heisler, M G; Atkinson, A; Bylstra, Y H; Walsh, R; Smyth, D R

    2001-04-01

    Studies involving mutants of the gene SPATULA indicate that it promotes the growth of carpel margins and of pollen tract tissues derived from them. We show that it encodes a new member of the basic-helix-loop-helix family of transcription factors. SPATULA is expressed in marginal and pollen tract tissues throughout their development confirming its role in regulating their growth. It is also expressed in many other tissues where it may act redundantly to control growth, including the peripheral zone of the shoot apical meristem, and specific tissues within leaves, petals, stamens and roots. Expression in the stomium, funiculus and valve dehiscence zone indicates an additional role in abscission. SPATULA expression does not require the function of the other carpel development genes CRABS CLAW and AGAMOUS, although its expression is repressed in first whorl organs by the A function gene APETALA2. Further, we have shown that disruptions to gynoecial pattern formation seen in ettin mutants can largely be attributed to ectopic SPATULA action. ETTIN's role seems to be to negatively regulate SPATULA expression in abaxial regions of the developing gynoecium. SPATULA is the first basic-helix-loop-helix gene in plants known to play a role in floral organogenesis. PMID:11245574

  18. The MYB182 Protein Down-Regulates Proanthocyanidin and Anthocyanin Biosynthesis in Poplar by Repressing Both Structural and Regulatory Flavonoid Genes1[OPEN

    PubMed Central

    Yoshida, Kazuko; Ma, Dawei; Constabel, C. Peter

    2015-01-01

    Trees in the genus Populus (poplar) contain phenolic secondary metabolites including the proanthocyanidins (PAs), which help to adapt these widespread trees to diverse environments. The transcriptional activation of PA biosynthesis in response to herbivory and ultraviolet light stress has been documented in poplar leaves, and a regulator of this process, the R2R3-MYB transcription factor MYB134, has been identified. MYB134-overexpressing transgenic plants show a strong high-PA phenotype. Analysis of these transgenic plants suggested the involvement of additional MYB transcription factors, including repressor-like MYB factors. Here, MYB182, a subgroup 4 MYB factor, was found to act as a negative regulator of the flavonoid pathway. Overexpression of MYB182 in hairy root culture and whole poplar plants led to reduced PA and anthocyanin levels as well as a reduction in the expression of key flavonoid genes. Similarly, a reduced accumulation of transcripts of a MYB PA activator and a basic helix-loop-helix cofactor was observed in MYB182-overexpressing hairy roots. Transient promoter activation assays in poplar cell culture demonstrated that MYB182 can disrupt transcriptional activation by MYB134 and that the basic helix-loop-helix-binding motif of MYB182 was essential for repression. Microarray analysis of transgenic plants demonstrated that down-regulated targets of MYB182 also include shikimate pathway genes. This work shows that MYB182 plays an important role in the fine-tuning of MYB134-mediated flavonoid metabolism. PMID:25624398

  19. MyoD and myogenin act on the chicken myosin light-chain 1 gene as distinct transcriptional factors.

    PubMed Central

    Asakura, A; Fujisawa-Sehara, A; Komiya, T; Nabeshima, Y; Nabeshima, Y

    1993-01-01

    Expression of MyoD, myogenin, MRF4, and Myf-5 converts nonmuscle cells to muscle cells. In an attempt to analyze the roles of these factors, we have investigated their effects on transcription driven by the promoter of the chicken myosin alkaline light-chain (MLC1) gene. The activation by CMD1 or c-myogenin (chicken MyoD or myogenin, respectively) was dependent on the existence of a muscle-specific regulatory region located from positions -2096 to -1743. Its distal half, containing a pair of E boxes (CANNTG), had been previously characterized as an enhancer responsive to CMD1 but not to c-myogenin. In this study, we report the identification of another enhancer in the muscle-specific regulatory region which is preferentially responsive to c-myogenin. Deletion and mutation analyses indicated that this enhancer requires a single E box and its flanking sequences. Furthermore, analysis of chimeric proteins of CMD1 and c-myogenin indicated that regions outside the basic helix-loop-helix domain of c-myogenin are involved in the specificity of the enhancer. These results show that CMD1 and c-myogenin act on the MLC1 gene by recognizing different upstream DNA sequences and that direct or indirect interactions between the regions outside the basic helix-loop-helix domain and flanking sequences of E boxes are involved in the target sequence specificity. Images PMID:8413304

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

    PubMed Central

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

    2015-01-01

    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

  1. Overexpression of Inhibitor of DNA-Binding 2 Attenuates Pulmonary Fibrosis through Regulation of c-Abl and Twist

    PubMed Central

    Yang, Jibing; Velikoff, Miranda; Agarwal, Manisha; Disayabutr, Supparerk; Wolters, Paul J.; Kim, Kevin K.

    2016-01-01

    Fibrosis is a multicellular process leading to excessive extracellular matrix deposition. Factors that affect lung epithelial cell proliferation and activation may be important regulators of the extent of fibrosis after injury. We and others have shown that activated alveolar epithelial cells (AECs) directly contribute to fibrogenesis by secreting mesenchymal proteins, such as type I collagen. Recent evidence suggests that epithelial cell acquisition of mesenchymal features during carcinogenesis and fibrogenesis is regulated by several mesenchymal transcription factors. Induced expression of direct inhibitors to these mesenchymal transcription factors offers a potentially novel therapeutic strategy. Inhibitor of DNA-binding 2 (Id2) is an inhibitory helix-loop-helix transcription factor that is highly expressed by lung epithelial cells during development and has been shown to coordinate cell proliferation and differentiation of cancer cells. We found that overexpression of Id2 in primary AECs promotes proliferation by inhibiting a retinoblastoma protein/c-Abl interaction leading to greater c-Abl activity. Id2 also blocks transforming growth factor β1–mediated expression of type I collagen by inhibiting Twist, a prominent mesenchymal basic helix-loop-helix transcription factor. In vivo, Id2 induced AEC proliferation and protected mice from lung fibrosis. By using a high-throughput screen, we found that histone deacetylase inhibitors induce Id2 expression by adult AECs. Collectively, these findings suggest that Id2 expression by AECs can be induced, and overexpression of Id2 affects AEC phenotype, leading to protection from fibrosis. PMID:25661109

  2. Formation of in vivo complexes between the TAL1 and E2A polypeptides of leukemic T cells.

    PubMed Central

    Hsu, H L; Wadman, I; Baer, R

    1994-01-01

    Tumor-specific activation of the TAL1 gene occurs in approximately 25% of patients with T-cell acute lymphoblastic leukemia (T-ALL). The TAL1 gene products possess a basic helix-loop-helix (bHLH) domain that interacts in vitro with the bHLH proteins (E12 and E47) encoded by the E2A locus. We have now applied two independent methods, the two-hybrid procedure and co-immunoprecipitation analysis, to demonstrate that TAL1 and E2A polypeptides also associate in vivo. These studies show that the bHLH domain of TAL1 selectively interacts with the bHLH domains of E12 and E47, but not with the Id1 helix-loop-helix protein. TAL1 does not self-associate to form homodimeric complexes, implying that the in vivo functions of TAL1 depend on heterologous interaction with other bHLH proteins such as E12 and E47. Co-immunoprecipitation analysis revealed the presence of endogenous TAL1/E2A complexes in Jurkat cells, a leukemic line derived from a T-ALL patient. Thus, the malignant properties of TAL1 may be due to obligate interaction with the E2A polypeptides. Images PMID:8159721

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

    PubMed Central

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

    2014-01-01

    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

  4. The bHLH transcription factor HBI1 mediates the trade-off between growth and pathogen-associated molecular pattern-triggered immunity in Arabidopsis.

    PubMed

    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

    2014-02-01

    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

  5. Cross-talk between distinct nuclear import pathways enables efficient nuclear import of E47 in conjunction with its partner transcription factors

    PubMed Central

    Mehmood, Rashid; Yasuhara, Noriko; Fukumoto, Masahiro; Oe, Souichi; Tachibana, Taro; Yoneda, Yoshihiro

    2011-01-01

    Nuclear import of karyophilic proteins is carried out by a variety of mechanisms. We previously showed that two basic helix-loop-helix proteins, NeuroD1 and E47, synergistically affect each other's nuclear import. In this study, we dissected the molecular pathways underlying nuclear import of the NeuroD1/E47 heterodimer. In vitro nuclear import assays indicated that importin α family members are the major nuclear import receptors for E47. However, inhibition of importin α resulted in cytoplasmic retention of E47 that could be rescued by its binding partner, NeuroD1, through heterodimerization. In addition, nuclear import of NeuroD1 was importin α independent but importin β1 dependent. In primary neurons, localization of endogenous E47 was not affected by importin α inhibition, suggesting that neuronal E47 could be imported into the nucleus as a heterodimer with NeuroD1 by using importin β1 alone. We also found that E47 had similar nuclear import characteristics in C2C12 cells, where E47 heterodimerized with MyoD, another helix-loop-helix protein, suggesting functional conservation within the same family of transcription factors. Collectively, our data reveal that E47 is imported into the nucleus via multiple pathways, depending on the molecular binding mode, establishing a previously uncharacterized cross-talk between two distinct nuclear import pathways. PMID:21832153

  6. HaloTag protein-mediated specific labeling of living cells with quantum dots

    SciTech Connect

    So, Min-kyung; Yao Hequan; Rao Jianghong

    2008-09-26

    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.

  7. Cooxidation of styrene by horseradish peroxidase and phenols. A biochemical model for protein-mediated cooxidation

    SciTech Connect

    Ortiz de Montellano, P.R.; Grab, L.A.

    1987-08-25

    Styrene is oxidized to styrene oxide and benzaldehyde when incubated with horseradish peroxidase, H/sub 2/O/sub 2/, and 4-methylphenol. Styrene oxide is not formed in the absence of any of these reaction components or of molecular oxygen. The coupling products 2-(4-methylphenoxy)-1-phenylethane, 2-(4-methylphenoxy)-1-phenylethan-1-ol, and 2-(4-methylphenoxy)-2-phenylethan-1-ol are not formed, but the ortho-linked dimer of 4-methylphenol is a major product. The epoxide oxygen is labeled in the presence of /sup 18/O/sub 2/ but not H/sub 2/ /sup 18/O/sub 2/. Styrene oxide formation is not inhibited by mannitol or superoxide dismutase. The stereochemistry of trans-(1-/sup 2/H)styrene is partially scrambled in the epoxide product. EPR signals attributable to the 2,4-dihydroxyl-5-methylphenoxy radical, a product of the oxidation of 4-methylcatechol, are observed if Zn/sup 2 +/ is added to stabilize the radical. This radical is only detected in the presence of styrene. The results imply that styrene is epoxidized by the hydroperoxy radical generated by addition of molecular oxygen to the 4-methylphenoxy radical. The epoxidation mimics the chemistry proposed to occur in the protein-mediated cooxidation of styrene by hemoglobin and myoglobin.

  8. Refractive-index-based screening of membrane-protein-mediated transfer across biological membranes.

    PubMed

    Brändén, Magnus; Tabaei, Seyed R; Fischer, Gerhard; Neutze, Richard; Höök, Fredrik

    2010-07-01

    Numerous membrane-transport proteins are major drug targets, and therefore a key ingredient in pharmaceutical development is the availability of reliable, efficient tools for membrane transport characterization and inhibition. Here, we present the use of evanescent-wave sensing for screening of membrane-protein-mediated transport across lipid bilayer membranes. This method is based on a direct recording of the temporal variations in the refractive index that occur upon a transfer-dependent change in the solute concentration inside liposomes associated to a surface plasmon resonance (SPR) active sensor surface. The applicability of the method is demonstrated by a functional study of the aquaglyceroporin PfAQP from the malaria parasite Plasmodium falciparum. Assays of the temperature dependence of facilitated diffusion of sugar alcohols on a single set of PfAQP-reconstituted liposomes reveal that the activation energies for facilitated diffusion of xylitol and sorbitol are the same as that previously measured for glycerol transport in the aquaglyceroporin of Escherichia coli (5 kcal/mole). These findings indicate that the aquaglyceroporin selectivity filter does not discriminate sugar alcohols based on their length, and that the extra energy cost of dehydration of larger sugar alcohols, upon entering the pore, is compensated for by additional hydrogen-bond interactions within the aquaglyceroporin pore. PMID:20655840

  9. RNA-induced silencing attenuates G protein-mediated calcium signals.

    PubMed

    Philip, Finly; Sahu, Shriya; Golebiewska, Urszula; Scarlata, Suzanne

    2016-05-01

    Phospholipase Cβ (PLCβ) is activated by G protein subunits in response to environmental stimuli to increase intracellular calcium. In cells, a significant portion of PLCβ is cytosolic, where it binds a protein complex required for efficient RNA-induced silencing called C3PO (component 3 promoter of RISC). Binding between C3PO and PLCβ raises the possibility that RNA silencing activity can affect the ability of PLCβ to mediate calcium signals. By use of human and rat neuronal cell lines (SK-N-SH and PC12), we show that overexpression of one of the main components of C3PO diminishes Ca(2+) release in response to Gαq/PLCβ stimulation by 30 to 40%. In untransfected SK-N-SH or PC12 cells, the introduction of siRNA(GAPDH) [small interfering RNA(glyceraldehyde 3-phosphate dehydrogenase)] reduces PLCβ-mediated calcium signals by ∼30%, but addition of siRNA(Hsp90) (heat shock protein 90) had little effect. Fluorescence imaging studies suggest an increase in PLCβ-C3PO association in cells treated with siRNA(GAPDH) but not siRNA(Hsp90). Taken together, our studies raise the possibility that Ca(2+) responses to extracellular stimuli can be modulated by components of the RNA silencing machinery.-Philip, F., Sahu, S., Golebiewska, U., Scarlata, S. RNA-induced silencing attenuates G protein-mediated calcium signals. PMID:26862135

  10. Refractive-Index-Based Screening of Membrane-Protein-Mediated Transfer across Biological Membranes

    PubMed Central

    Brndn, Magnus; Tabaei, Seyed R.; Fischer, Gerhard; Neutze, Richard; Hk, Fredrik

    2010-01-01

    Abstract Numerous membrane-transport proteins are major drug targets, and therefore a key ingredient in pharmaceutical development is the availability of reliable, efficient tools for membrane transport characterization and inhibition. Here, we present the use of evanescent-wave sensing for screening of membrane-protein-mediated transport across lipid bilayer membranes. This method is based on a direct recording of the temporal variations in the refractive index that occur upon a transfer-dependent change in the solute concentration inside liposomes associated to a surface plasmon resonance (SPR) active sensor surface. The applicability of the method is demonstrated by a functional study of the aquaglyceroporin PfAQP from the malaria parasite Plasmodium falciparum. Assays of the temperature dependence of facilitated diffusion of sugar alcohols on a single set of PfAQP-reconstituted liposomes reveal that the activation energies for facilitated diffusion of xylitol and sorbitol are the same as that previously measured for glycerol transport in the aquaglyceroporin of Escherichia coli (5 kcal/mole). These findings indicate that the aquaglyceroporin selectivity filter does not discriminate sugar alcohols based on their length, and that the extra energy cost of dehydration of larger sugar alcohols, upon entering the pore, is compensated for by additional hydrogen-bond interactions within the aquaglyceroporin pore. PMID:20655840

  11. Natural products induce a G protein-mediated calcium pathway activating p53 in cancer cells.

    PubMed

    van Ginkel, Paul R; Yan, Michael B; Bhattacharya, Saswati; Polans, Arthur S; Kenealey, Jason D

    2015-11-01

    Paclitaxel, etoposide, vincristine and doxorubicin are examples of natural products being used as chemotherapeutics but with adverse side effects that limit their therapeutic window. Natural products derived from plants and having low toxicity, such as quercetin, resveratrol, epigallocatechin gallate and piceatannol, have been shown to inhibit tumor cell growth both in vitro and in pre-clinical models of cancer, but their mechanisms of action have not been fully elucidated, thus restricting their use as prototypes for developing synthetic analogs with improved anti-cancer properties. We and others have demonstrated that one of the earliest and consistent events upon exposure of tumor cells to these less toxic natural products is a rise in cytoplasmic calcium, activating several pro-apoptotic pathways. We describe here a G protein/inositol 1,4,5-trisphosphate pathway (InsP3) in MDA-MB-231 human breast cancer cells that mediates between these less toxic natural products and the release of calcium from the endoplasmic reticulum. Further, we demonstrate that this elevation of intracellular calcium modulates p53 activity and the subsequent transcription of several pro-apoptotic genes encoding PIG8, CD95, PIDD, TP53INP, RRM2B, Noxa, p21 and PUMA. We conclude from our findings that less toxic natural products likely bind to a G protein coupled receptor that activates a G protein-mediated and calcium-dependent pathway resulting selectively in tumor cell death. PMID:26341291

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

    PubMed Central

    Pingret, JL; Journet, EP; Barker, DG

    1998-01-01

    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

  13. Radiation Basics

    MedlinePlus

    ... Radiation Protection » Radiation Basics Radiation Basics Radiation is energy. It can come from unstable atoms that undergo ... travels from its source in the form of energy waves or energized particles. There are two kinds ...

  14. Asthma Basics

    MedlinePlus

    ... Caring for Your Child All About Food Allergies Asthma Basics KidsHealth > For Parents > Asthma Basics Print A ... Asthma Categories en español Asma: aspectos fundamentales About Asthma Asthma is a common lung condition in kids ...

  15. Effect of Reactor Turbulence on the Binding-Protein-Mediated Aspartate Transport System in Thin Wastewater Biofilms

    PubMed Central

    Eighmy, T. Taylor; Bishop, P. L.

    1985-01-01

    This research documents an effect of reactor turbulence on the ability of gram-negative wastewater biofilm bacteria to actively transport l-aspartate via a binding-protein-mediated transport system. Biofilms which were not preadapted to turbulence and which possessed two separate and distinct aspartate transport systems (systems 1 and 2) were subjected to a turbulent flow condition in a hydrodynamically defined closed-loop reactor system. A shear stress treatment of 3.1 N · m−2 for 10 min at a turbulent Reynolds number (Re = 11,297) inactivated the low-affinity, high-capacity binding-protein-mediated transport system (system 2) and resolved the high-affinity, low-capacity membrane-bound proton symport system (system 1). The Kt and Vmax values for the resolved system were statistically similar to Kt and Vmax values for system 1 when system 2 was inactivated either by osmotic shock or arsenate, two treatments which are known to inactivate binding-protein-mediated transport systems. We hypothesize that shear stress disrupts system 2 by deforming the outer membranes of the firmly adhered gram-negative bacteria. PMID:16346830

  16. Poly(rC) binding proteins mediate poliovirus mRNA stability.

    PubMed

    Murray, K E; Roberts, A W; Barton, D J

    2001-08-01

    The 5'-terminal 88 nt of poliovirus RNA fold into a cloverleaf RNA structure and form ribonucleoprotein complexes with poly(rC) binding proteins (PCBPs; AV Gamarnik, R Andino, RNA, 1997, 3:882-892; TB Parsley, JS Towner, LB Blyn, E Ehrenfeld, BL Semler, RNA, 1997, 3:1124-1134). To determine the functional role of these ribonucleoprotein complexes in poliovirus replication, HeLa S10 translation-replication reactions were used to quantitatively assay poliovirus mRNA stability, poliovirus mRNA translation, and poliovirus negative-strand RNA synthesis. Ribohomopoly(C) RNA competitor rendered wild-type poliovirus mRNA unstable in these reactions. A 5'-terminal 7-methylguanosine cap prevented the degradation of wild-type poliovirus mRNA in the presence of ribohomopoly(C) competitor. Ribohomopoly(A), -(G), and -(U) did not adversely affect poliovirus mRNA stability. Ribohomopoly(C) competitor RNA inhibited the translation of poliovirus mRNA but did not inhibit poliovirus negative-strand RNA synthesis when poliovirus replication proteins were provided in trans using a chimeric helper mRNA possessing the hepatitis C virus IRES. A C24A mutation prevented UV crosslinking of PCBPs to 5' cloverleaf RNA and rendered poliovirus mRNA unstable. A 5'-terminal 7-methylguanosine cap blocked the degradation of C24A mutant poliovirus mRNA. The C24A mutation did not inhibit the translation of poliovirus mRNA nor diminish viral negative-strand RNA synthesis relative to wild-type RNA. These data support the conclusion that poly(rC) binding protein(s) mediate the stability of poliovirus mRNA by binding to the 5'-terminal cloverleaf structure of poliovirus mRNA. Because of the general conservation of 5' cloverleaf RNA sequences among picornaviruses, including C24 in loop b of the cloverleaf, we suggest that viral mRNA stability of polioviruses, coxsackieviruses, echoviruses, and rhinoviruses is mediated by interactions between PCBPs and 5' cloverleaf RNA. PMID:11497431

  17. Poly(rC) binding proteins mediate poliovirus mRNA stability.

    PubMed Central

    Murray, K E; Roberts, A W; Barton, D J

    2001-01-01

    The 5'-terminal 88 nt of poliovirus RNA fold into a cloverleaf RNA structure and form ribonucleoprotein complexes with poly(rC) binding proteins (PCBPs; AV Gamarnik, R Andino, RNA, 1997, 3:882-892; TB Parsley, JS Towner, LB Blyn, E Ehrenfeld, BL Semler, RNA, 1997, 3:1124-1134). To determine the functional role of these ribonucleoprotein complexes in poliovirus replication, HeLa S10 translation-replication reactions were used to quantitatively assay poliovirus mRNA stability, poliovirus mRNA translation, and poliovirus negative-strand RNA synthesis. Ribohomopoly(C) RNA competitor rendered wild-type poliovirus mRNA unstable in these reactions. A 5'-terminal 7-methylguanosine cap prevented the degradation of wild-type poliovirus mRNA in the presence of ribohomopoly(C) competitor. Ribohomopoly(A), -(G), and -(U) did not adversely affect poliovirus mRNA stability. Ribohomopoly(C) competitor RNA inhibited the translation of poliovirus mRNA but did not inhibit poliovirus negative-strand RNA synthesis when poliovirus replication proteins were provided in trans using a chimeric helper mRNA possessing the hepatitis C virus IRES. A C24A mutation prevented UV crosslinking of PCBPs to 5' cloverleaf RNA and rendered poliovirus mRNA unstable. A 5'-terminal 7-methylguanosine cap blocked the degradation of C24A mutant poliovirus mRNA. The C24A mutation did not inhibit the translation of poliovirus mRNA nor diminish viral negative-strand RNA synthesis relative to wild-type RNA. These data support the conclusion that poly(rC) binding protein(s) mediate the stability of poliovirus mRNA by binding to the 5'-terminal cloverleaf structure of poliovirus mRNA. Because of the general conservation of 5' cloverleaf RNA sequences among picornaviruses, including C24 in loop b of the cloverleaf, we suggest that viral mRNA stability of polioviruses, coxsackieviruses, echoviruses, and rhinoviruses is mediated by interactions between PCBPs and 5' cloverleaf RNA. PMID:11497431

  18. Heterotrimeric G protein mediates ethylene-induced stomatal closure via hydrogen peroxide synthesis in Arabidopsis.

    PubMed

    Ge, Xiao-Min; Cai, Hong-Li; Lei, Xue; Zhou, Xue; Yue, Ming; He, Jun-Min

    2015-04-01

    Heterotrimeric G proteins function as key players in hydrogen peroxide (H2O2) production in plant cells, but whether G proteins mediate ethylene-induced H2O2 production and stomatal closure are not clear. Here, evidences are provided to show the Gα subunit GPA1 as a missing link between ethylene and H2O2 in guard cell ethylene signalling. In wild-type leaves, ethylene-triggered H2O2 synthesis and stomatal closure were dependent on activation of Gα. GPA1 mutants showed the defect of ethylene-induced H2O2 production and stomatal closure, whereas wGα and cGα overexpression lines showed faster stomatal closure and H2O2 production in response to ethylene. Ethylene-triggered H2O2 generation and stomatal closure were impaired in RAN1, ETR1, ERS1 and EIN4 mutants but not impaired in ETR2 and ERS2 mutants. Gα activator and H2O2 rescued the defect of RAN1 and EIN4 mutants or etr1-3 in ethylene-induced H2O2 production and stomatal closure, but only rescued the defect of ERS1 mutants or etr1-1 and etr1-9 in ethylene-induced H2O2 production. Stomata of CTR1 mutants showed constitutive H2O2 production and stomatal closure, but which could be abolished by Gα inhibitor. Stomata of EIN2, EIN3 and ARR2 mutants did not close in responses to ethylene, Gα activator or H2O2, but do generate H2O2 following challenge of ethylene or Gα activator. The data indicate that Gα mediates ethylene-induced stomatal closure via H2O2 production, and acts downstream of RAN1, ETR1, ERS1, EIN4 and CTR1 and upstream of EIN2, EIN3 and ARR2. The data also show that ETR1 and ERS1 mediate both ethylene and H2O2 signalling in guard cells. PMID:25704455

  19. Basic Warehousing.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    Developed as part of the Marine Corps Institute (MCI) correspondence training program, this course on basic warehousing is designed to provide Marines with Military Occupation Speciality 3051 in the rank of private through corporal with instruction in those basic principles, methods, and procedures that can be applied to any warehousing or storage…

  20. Anesthesia Basics

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Anesthesia Basics KidsHealth > For Teens > Anesthesia Basics Print A ... español Conceptos básicos sobre la anestesia What Is Anesthesia? No doubt about it, getting an operation can ...

  1. Body Basics

    MedlinePlus

    ... About Food Allergies About Body Basics KidsHealth > For Parents > About Body Basics Print A A A Text Size Remember the biology class you had in high school? Well, even if you do, lots of new knowledge about how the body works helps us to ...

  2. French Basic Course: Basic Situations.

    ERIC Educational Resources Information Center

    Defense Language Inst., Monterey, CA.

    This volume of the French Basic Course contains ten situations from daily life, each divided into five sub-situations. The material for each situation consists of cartoons and lists of selected words. The purpose of the volume is to provide a vehicle for reviewing the grammar and vocabulary of lessons 1-85 of the Basic Course and adding new words…

  3. Basic Finance

    NASA Technical Reports Server (NTRS)

    Vittek, J. F.

    1972-01-01

    A discussion of the basic measures of corporate financial strength, and the sources of the information is reported. Considered are: balance sheet, income statement, funds and cash flow, and financial ratios.

  4. Fluoridation Basics

    MedlinePlus

    ... Water Fluoridation Journal Articles for Community Water Fluoridation Water Fluoridation Basics Recommend on Facebook Tweet Share Compartir ... because of tooth decay. History of Fluoride in Water In the 1930s, scientists examined the relationship between ...

  5. The Basics

    ERIC Educational Resources Information Center

    Indrisano, Roselmina; And Others

    1976-01-01

    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)

  6. Lipid transfer protein-mediated resistance to a trichothecene mycotoxin – Novel players in FHB resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lipid transfer proteins are a class of basic cysteine rich proteins characterized by an eight cysteine motif backbone with intrinsic antimicrobial activities against bacterial and fungal pathogens. Previously, we identified two type IV nonspecific lipid transfer protein (nsLTP) genes (LTP4.4 and LTP...

  7. DOS basics

    SciTech Connect

    O`Connor, P.

    1994-09-01

    DOS is an acronym for Disk Operating System. It is actually a set of programs that allows you to control your personal computer. DOS offers the capabilities to create and manage files; organize and maintain information placed on disks; use application programs such as WordPerfect, Lotus 123, Excel, Windows, etc. In addition, DOS provides the basic utilities needed to copy files from one area to another, delete files and list files. The latest version of DOS also offers more advanced features that include hard disk compression and memory management. Basic DOS commands are discussed.

  8. Basic Science.

    ERIC Educational Resources Information Center

    Mercer County Community Coll., Trenton, NJ.

    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…

  9. Basic Education.

    ERIC Educational Resources Information Center

    Robinson, Virginia, Ed.

    1984-01-01

    This issue of "Basic Education" is devoted to the arts in education as a concern that should be addressed in a time of new priorities for the curriculum. Five articles and a book review are included. The opening article, "The State of the Arts in Education: Envisioning Active Participation By All" (Virginia Robinson), emphasizes that the study of…

  10. Basic Backwardness.

    ERIC Educational Resources Information Center

    Weingartner, Charles

    This paper argues that the "back to basics" movement is regressive and that regression is the characteristic mode of fear-ridden personalities. It is argued that many people in American society today have lost their ability to laugh and do not have the sense of humor which is crucial to a healthy mental state. Such topics as necrophilia, mental…

  11. Basic Horticulture.

    ERIC Educational Resources Information Center

    Geer, Barbra Farabough

    This learning packet contains teaching suggestions and student learning materials for a course in basic horticulture aimed at preparing students for employment in a number of horticulture areas. The packet includes nine sections and twenty instructional units. Following the standard format established for Oklahoma vocational education materials in…

  12. Ethanol Basics

    SciTech Connect

    2015-01-30

    Ethanol is a widely-used, domestically-produced renewable fuel made from corn and other plant materials. More than 96% of gasoline sold in the United States contains ethanol. Learn more about this alternative fuel in the Ethanol Basics Fact Sheet, produced by the U.S. Department of Energy's Clean Cities program.

  13. Basic Skills--Basic Business.

    ERIC Educational Resources Information Center

    Conference Board of Canada, Ottawa (Ontario).

    The experience of eight prominent Canadian business organizations was examined in terms of how basic skills deficits are identified in their work force, the impact of those deficiencies on organizational competitiveness, and why corporate programs are developed in response to the issue. Some of the key findings were as follows: (1) employee…

  14. Direct Detection of Transcription Factors in Cotyledons during Seedling Development Using Sensitive Silicon-Substrate Photonic Crystal Protein Arrays1[OPEN

    PubMed Central

    Jones, Sarah I.; Tan, Yafang; Shamimuzzaman, Md; George, Sherine; Cunningham, Brian T.; Vodkin, Lila

    2015-01-01

    Transcription factors control important gene networks, altering the expression of a wide variety of genes, including those of agronomic importance, despite often being expressed at low levels. Detecting transcription factor proteins is difficult, because current high-throughput methods may not be sensitive enough. One-dimensional, silicon-substrate photonic crystal (PC) arrays provide an alternative substrate for printing multiplexed protein microarrays that have greater sensitivity through an increased signal-to-noise ratio of the fluorescent signal compared with performing the same assay upon a traditional aminosilanized glass surface. As a model system to test proof of concept of the silicon-substrate PC arrays to directly detect rare proteins in crude plant extracts, we selected representatives of four different transcription factor families (zinc finger GATA, basic helix-loop-helix, BTF3/NAC [for basic transcription factor of the NAC family], and YABBY) that have increasing transcript levels during the stages of seedling cotyledon development. Antibodies to synthetic peptides representing the transcription factors were printed on both glass slides and silicon-substrate PC slides along with antibodies to abundant cotyledon proteins, seed lectin, and Kunitz trypsin inhibitor. The silicon-substrate PC arrays proved more sensitive than those performed on glass slides, detecting rare proteins that were below background on the glass slides. The zinc finger transcription factor was detected on the PC arrays in crude extracts of all stages of the seedling cotyledons, whereas YABBY seemed to be at the lower limit of their sensitivity. Interestingly, the basic helix-loop-helix and NAC proteins showed developmental profiles consistent with their transcript patterns, indicating proof of concept for detecting these low-abundance proteins in crude extracts. PMID:25635113

  15. Homeodomain-Leucine Zipper II family of transcription factors to the limelight: central regulators of plant development.

    PubMed

    Carabelli, Monica; Turchi, Luana; Ruzza, Valentino; Morelli, Giorgio; Ruberti, Ida

    2013-09-01

    The Arabidopsis genome encodes 10 Homeodomain-Leucine Zipper (HD-Zip) II transcription factors that can be subdivided into 4 clades (α-δ). All the γ (ARABIDOPSIS THALIANA HOMEOBOX 2 [ATHB2], HOMEOBOX ARABIDOPSIS THALIANA 1 [HAT1], HAT2) and δ (HAT3, ATHB4) genes are regulated by light quality changes (Low Red [R]/Far-Red [FR]) that induce the shade avoidance response in most of the angiosperms. HD-Zip IIγ and HD-Zip IIδ transcription factors function as positive regulators of shade avoidance, and there is evidence that at least ATHB2 is directly positively regulated by the basic Helix-Loop-Helix (bHLH) proteins PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5. Recent evidence demonstrate that, in addition to their function in shade avoidance, HD-Zip IIγ and HD-Zip IIδ proteins play an essential role in plant development from embryogenesis onwards in a white light environment. PMID:23838958

  16. Aryl Hydrocarbon Receptor Control of Adaptive Immunity

    PubMed Central

    2013-01-01

    The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that belongs to the family of basic helix-loop-helix transcription factors. Although the AhR was initially recognized as the receptor mediating the pathologic effects of dioxins and other pollutants, the activation of AhR by endogenous and environmental factors has important physiologic effects, including the regulation of the immune response. Thus, the AhR provides a molecular pathway through which environmental factors modulate the immune response in health and disease. In this review, we discuss the role of AhR in the regulation of the immune response, the source and chemical nature of AhR ligands, factors controlling production and degradation of AhR ligands, and the potential to target the AhR for therapeutic immunomodulation. PMID:23908379

  17. Direct roles of SPEECHLESS in the specification of stomatal self-renewing cells.

    PubMed

    Lau, On Sun; Davies, Kelli A; Chang, Jessica; Adrian, Jessika; Rowe, Matthew H; Ballenger, Catherine E; Bergmann, Dominique C

    2014-09-26

    Lineage-specific stem cells are critical for the production and maintenance of specific cell types and tissues in multicellular organisms. In Arabidopsis, the initiation and proliferation of stomatal lineage cells is controlled by the basic helix-loop-helix transcription factor SPEECHLESS (SPCH). SPCH-driven asymmetric and self-renewing divisions allow flexibility in stomatal production and overall organ growth. How SPCH directs stomatal lineage cell behaviors, however, is unclear. Here, we improved the chromatin immunoprecipitation (ChIP) assay and profiled the genome-wide targets of Arabidopsis SPCH in vivo. We found that SPCH controls key regulators of cell fate and asymmetric cell divisions and modulates responsiveness to peptide and phytohormone-mediated intercellular communication. Our results delineate the molecular pathways that regulate an essential adult stem cell lineage in plants. PMID:25190717

  18. Exploring Functional Redundancy in the Immunoglobulin μ Heavy-Chain Gene Enhancer

    PubMed Central

    Dang, Wei; Nikolajczyk, Barbara S.; Sen, Ranjan

    1998-01-01

    Immunoglobulin (Ig) μ heavy-chain gene enhancer activity is mediated by multiple DNA binding proteins. Mutations of several protein binding sites in the enhancer do not affect enhancer activity significantly. This feature, termed redundancy, is thought to be due to functional compensation of the mutated sites by other elements within the enhancer. In this study, we identified the elements that make the basic helix-loop-helix (bHLH) protein binding sites, μE2 and μE3, redundant. The major compensatory element is a binding site for interferon regulatory factors (IRFs) and not one of several other bHLH protein binding sites. These studies also provide the first evidence for a role of IRF proteins in Ig heavy-chain gene expression. In addition, we reconstituted the activity of a monomeric μ enhancer in nonlymphoid cells and defined the domains of the ETS gene required for function. PMID:9774700

  19. Transcriptional Control of Early T and B Cell Developmental Choices

    PubMed Central

    Rothenberg, Ellen V.

    2014-01-01

    T and B cells share a common somatic gene rearrangement mechanism for assembling the genes that code for their antigen receptors and developmental pathways with many parallels. Shared usage of basic helix-loop-helix E proteins as transcriptional drivers underlies these common features. However, the transcription factor networks in which these E proteins are embedded are different both in membership and in architecture for T and B cell gene regulatory programs. These differences permit lineage commitment decisions to be made in different hierarchical orders. Furthermore, in a contrast to B-cell gene networks, the T-cell gene network architecture for effector differentiation is sufficiently modular so that E protein inputs can be removed. Complete “T-cell-like” effector differentiation can proceed without T-cell receptor rearrangement or selection when E proteins are neutralized, yielding natural killer and other innate lymphoid cells. PMID:24471430

  20. Proprioceptor pathway development is dependent on Math1

    NASA Technical Reports Server (NTRS)

    Bermingham, N. A.; Hassan, B. A.; Wang, V. Y.; Fernandez, M.; Banfi, S.; Bellen, H. J.; Fritzsch, B.; Zoghbi, H. Y.

    2001-01-01

    The proprioceptive system provides continuous positional information on the limbs and body to the thalamus, cortex, pontine nucleus, and cerebellum. We showed previously that the basic helix-loop-helix transcription factor Math1 is essential for the development of certain components of the proprioceptive pathway, including inner-ear hair cells, cerebellar granule neurons, and the pontine nuclei. Here, we demonstrate that Math1 null embryos lack the D1 interneurons and that these interneurons give rise to a subset of proprioceptor interneurons and the spinocerebellar and cuneocerebellar tracts. We also identify three downstream genes of Math1 (Lh2A, Lh2B, and Barhl1) and establish that Math1 governs the development of multiple components of the proprioceptive pathway.

  1. Type I bHLH Proteins Daughterless and Tcf4 Restrict Neurite Branching and Synapse Formation by Repressing Neurexin in Postmitotic Neurons.

    PubMed

    D'Rozario, Mitchell; Zhang, Ting; Waddell, Edward A; Zhang, Yonggang; Sahin, Cem; Sharoni, Michal; Hu, Tina; Nayal, Mohammad; Kutty, Kaveesh; Liebl, Faith; Hu, Wenhui; Marenda, Daniel R

    2016-04-12

    Proneural proteins of the class I/II basic-helix-loop-helix (bHLH) family are highly conserved transcription factors. Class I bHLH proteins are expressed in a broad number of tissues during development, whereas class II bHLH protein expression is more tissue restricted. Our understanding of the function of class I/II bHLH transcription factors in both invertebrate and vertebrate neurobiology is largely focused on their function as regulators of neurogenesis. Here, we show that the class I bHLH proteins Daughterless and Tcf4 are expressed in postmitotic neurons in Drosophila melanogaster and mice, respectively, where they function to restrict neurite branching and synapse formation. Our data indicate that Daughterless performs this function in part by restricting the expression of the cell adhesion molecule Neurexin. This suggests a role for these proteins outside of their established roles in neurogenesis. PMID:27050508

  2. Flavonoids: biosynthesis, biological functions, and biotechnological applications

    PubMed Central

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

    2012-01-01

    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

  3. Potential for neural regeneration after neurotoxic injury in the adult mammalian retina

    NASA Astrophysics Data System (ADS)

    Ooto, Sotaro; Akagi, Tadamichi; Kageyama, Ryoichiro; Akita, Joe; Mandai, Michiko; Honda, Yoshihito; Takahashi, Masayo

    2004-09-01

    It has long been believed that the retina of mature mammals is incapable of regeneration. In this study, using the N-methyl-D-aspartate neurotoxicity model of adult rat retina, we observed that some Müller glial cells were stimulated to proliferate in response to a toxic injury and produce bipolar cells and rod photoreceptors. Although these newly produced neurons were limited in number, retinoic acid treatment promoted the number of regenerated bipolar cells. Moreover, misexpression of basic helix-loop-helix and homeobox genes promoted the induction of amacrine, horizontal, and rod photoreceptor specific phenotypes. These findings demonstrated that retinal neurons regenerated even in adult mammalian retina after toxic injury. Furthermore, we could partially control the fate of the regenerated neurons with extrinsic factors or intrinsic genes. The Müller glial cells constitute a potential source for the regeneration of adult mammalian retina and can be a target for drug delivery and gene therapy in retinal degenerative diseases.

  4. Lineage-specific stem cells, signals and asymmetries during stomatal development.

    PubMed

    Han, Soon-Ki; Torii, Keiko U

    2016-04-15

    Stomata are dispersed pores found in the epidermis of land plants that facilitate gas exchange for photosynthesis while minimizing water loss. Stomata are formed from progenitor cells, which execute a series of differentiation events and stereotypical cell divisions. The sequential activation of master regulatory basic-helix-loop-helix (bHLH) transcription factors controls the initiation, proliferation and differentiation of stomatal cells. Cell-cell communication mediated by secreted peptides, receptor kinases, and downstream mitogen-activated kinase cascades enforces proper stomatal patterning, and an intrinsic polarity mechanism ensures asymmetric cell divisions. As we review here, recent studies have provided insights into the intrinsic and extrinsic factors that control stomatal development. These findings have also highlighted striking similarities between plants and animals with regards to their mechanisms of specialized cell differentiation. PMID:27095491

  5. [Research progress of the bHLH transcription factors involved in genic male sterility in plants].

    PubMed

    Yongming, Liu; Ling, Zhang; Jianyu, Zhou; Moju, Cao

    2015-12-01

    Male sterility exists widely in the spermatophytes. It contributes to the study of plant reproductive development and can be used as an effective tool for hybrid seed production in heterosis utilization. Therefore, the study on male sterility is of great value in both theory and application. As one of the largest transcription factor families in plants, basic helix-loop-helix proteins (bHLHs) play a crucial role in regulating plant growth and development. This paper introduces the mechanism of bHLH regulating stamen development in several important model plants. Furthermore, we discuss the molecular mechanisms of genic male sterility resulting from bHLH dysfunction to provide references for crop breeding and theoretical studies. PMID:26704944

  6. The conserved WRPW motif of Hes6 mediates proteasomal degradation

    SciTech Connect

    Kang, Seon Ah; Seol, Jae Hong; Kim, Jaesang . E-mail: jkim1964@ewha.ac.kr

    2005-06-24

    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.

  7. A mitogen-activated protein kinase cascade module, MKK3-MPK6 and MYC2, is involved in blue light-mediated seedling development in Arabidopsis.

    PubMed

    Sethi, Vishmita; Raghuram, Badmi; Sinha, Alok Krishna; Chattopadhyay, Sudip

    2014-08-01

    Mitogen-activated protein kinase (MAPK) pathways are involved in several signal transduction processes in eukaryotes. Light signal transduction pathways have been extensively studied in plants; however, the connection between MAPK and light signaling pathways is currently unknown. Here, we show that MKK3-MPK6 is activated by blue light in a MYC2-dependent manner. MPK6 physically interacts with and phosphorylates a basic helix-loop-helix transcription factor, MYC2, and is phosphorylated by a MAPK kinase, MKK3. Furthermore, MYC2 binds to the MPK6 promoter and regulates its expression in a feedback regulatory mechanism in blue light signaling. We present mutational and physiological studies that illustrate the function of the MKK3-MPK6-MYC2 module in Arabidopsis thaliana seedling development and provide a revised mechanistic view of photomorphogenesis. PMID:25139007

  8. The Notch pathway inhibits TGFβ signaling in breast cancer through HEYL-mediated crosstalk.

    PubMed

    Han, Liangfeng; Diehl, Adam; Nguyen, Nguyen K; Korangath, Preethi; Teo, Weiwen; Cho, Soonweng; Kominsky, Scott; Huso, David L; Feigenbaum, Lionel; Rein, Alan; Argani, Pedram; Landberg, Goran; Gessler, Manfred; Sukumar, Saraswati

    2014-11-15

    Acquired resistance to TGFβ is a key step in the early stages of tumorigenesis. Mutations in TGFβ signaling components are rare, and little is known about the development of resistance in breast cancer. On the other hand, an activated Notch pathway is known to play a substantial role in promoting breast cancer development. Here, we present evidence of crosstalk between these two pathways through HEYL. HEYL, a basic helix-loop-helix transcription factor and a direct target of Notch signaling, is specifically overexpressed in breast cancer. HEYL represses TGFβ activity by binding to TGFβ-activated Smads. HeyL(-/-) mice have defective mammary gland development with fewer terminal end buds. On the other hand, HeyL transgenic mice show accelerated mammary gland epithelial proliferation and 24% of multiparous mice develop mammary gland cancer. Therefore, repression of TGFβ signaling by Notch acting through HEYL may promote initiation of breast cancer. PMID:25217524

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

    SciTech Connect

    Ohkuma, Mizue; Funato, Noriko; Higashihori, Norihisa; Murakami, Masanori; Ohyama, Kimie; Nakamura, Masataka . E-mail: naka.gene@cmn.tmd.ac.jp

    2007-01-26

    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.

  10. NeuroD-null mice are deaf due to a severe loss of the inner ear sensory neurons during development

    PubMed Central

    Kim, Woo-Young; Fritzsch, Bernd; Serls, Amanda; Bakel, Leigh Anne; Huang, Eric J.; Reichardt, Louis F.; Barth, Daniel S.; Lee, Jacqueline E.

    2009-01-01

    SUMMARY A key factor in the genetically programmed development of the nervous system is the death of massive numbers of neurons. Therefore, genetic mechanisms governing cell survival are of fundamental importance to developmental neuroscience. We report that inner ear sensory neurons are dependent on a basic helix-loop-helix transcription factor called NeuroD for survival during differentiation. Mice lacking NeuroD protein exhibit no auditory evoked potentials, reflecting a profound deafness. DiI fiber staining, immunostaining and cell death assays reveal that the deafness is due to the failure of inner ear sensory neuron survival during development. The affected inner ear sensory neurons fail to express neurotrophin receptors, TrkB and TrkC, suggesting that the ability of NeuroD to support neuronal survival may be directly mediated through regulation of responsiveness to the neurotrophins. PMID:11152640

  11. Structural basis of nucleic acid recognition by FK506-binding protein 25 (FKBP25), a nuclear immunophilin.

    PubMed

    Prakash, Ajit; Shin, Joon; Rajan, Sreekanth; Yoon, Ho Sup

    2016-04-01

    The nuclear immunophilin FKBP25 interacts with chromatin-related proteins and transcription factors and is suggested to interact with nucleic acids. Currently the structural basis of nucleic acid binding by FKBP25 is unknown. Here we determined the nuclear magnetic resonance (NMR) solution structure of full-length human FKBP25 and studied its interaction with DNA. The FKBP25 structure revealed that the N-terminal helix-loop-helix (HLH) domain and C-terminal FK506-binding domain (FKBD) interact with each other and that both of the domains are involved in DNA binding. The HLH domain forms major-groove interactions and the basic FKBD loop cooperates to form interactions with an adjacent minor-groove of DNA. The FKBP25-DNA complex model, supported by NMR and mutational studies, provides structural and mechanistic insights into the nuclear immunophilin-mediated nucleic acid recognition. PMID:26762975

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

    PubMed Central

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

    2014-01-01

    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

  13. Formation of the Embryonic Head in the Mouse: Attributes of a Gene Regulatory Network.

    PubMed

    Tam, Patrick P L; Fossat, Nicolas; Wilkie, Emilie; Loebel, David A F; Ip, Chi Kin; Ramialison, Mirana

    2016-01-01

    The embryonic head is the first major body part to be constructed during embryogenesis. The allocation and the assembly of the progenitor tissues, which start at gastrulation, are accompanied by the spatiotemporal activity of transcription factors and signaling pathways that drives lineage specification, germ layer formation, and cell/tissue movement. The morphogenesis, regionalization, and patterning of the brain and craniofacial structures rely on the function of LIM-domain, homeodomain, and basic helix-loop-helix transcription factors. These factors constitute the central nodes of a gene regulatory network (GRN) which encompasses and intersects with signaling pathways involved with head formation. It is predicted that the functional output of this "head GRN" impacts on cellular function and cell-cell interactions that are essential for lineage differentiation and tissue modeling, which are key processes underpinning the formation of the head. PMID:26969997

  14. The Drosophila melanogaster similar bHLH-PAS gene encodes a protein related to human hypoxia-inducible factor 1 alpha and Drosophila single-minded.

    PubMed

    Nambu, J R; Chen, W; Hu, S; Crews, S T

    1996-06-26

    The Drosophila melanogaster (Dm) similar (sima) gene was isolated using a low-stringency hybridization screen employing a Dm single-minded gene basic helix-loop-helix (bHLH) DNA probe. sima is a member of the bHLH-PAS gene family and the conceptual protein shares a number of structural features, including a bHLH domain, PAS domain, and homopolymeric amino acid stretches. Sima is most closely related to the human hypoxia-inducible factor 1 alpha bHLH-PAS protein. In situ hybridization experiments reveal that sima is transcribed in most or all cells throughout embryogenesis. It has been cytologically mapped to position 99D on the third chromosome, and is not closely linked to other known bHLH-PAS genes. PMID:8682312

  15. Launching the T-Lineage Developmental Programme

    PubMed Central

    Rothenberg, Ellen V.; Moore, Jonathan E.; Yui, Mary A.

    2011-01-01

    Preface Multipotent blood progenitor cells enter the thymus and begin a protracted differentiation process in which they gradually acquire T-cell characteristics while shedding their legacy of developmental plasticity. Notch signalling and basic helix-loop-helix E-protein transcription factors collaborate repeatedly to trigger and sustain this process throughout the period leading up to T-cell lineage commitment. Nevertheless, the process is discontinuous with separately regulated steps that demand roles for additional collaborating factors. This review discusses new evidence on the coordination of specification and commitment in the early T-cell pathway; effects of microenvironmental signals; the inheritance of stem-cell regulatory factors; and the ensemble of transcription factors that modulate the effects of Notch and E proteins, to distinguish individual stages and to polarize T-lineage fate determination. PMID:18097446

  16. Phenolic compounds from the bark of Oroxylum indicum activate the Ngn2 promoter.

    PubMed

    Fuentes, Rolly G; Arai, Midori A; Sadhu, Samir K; Ahmed, Firoj; Ishibashi, Masami

    2015-10-01

    A reporter gene assay that detects neurogenin 2 (Ngn2) promoter activity was utilized to identify compounds that induce neuronal differentiation. Ngn2 is a basic helix-loop-helix transcription factor that activates transcription of pro-neural genes. Using this assay system and an activity-guided approach, seven phenolic compounds were isolated from the methanol extract of Oroxylum indicum: 1 oroxylin A, 2 chrysin, 3 hispidulin, 4 baicalein, 5 apigenin, 6 baicalin, and 7 isoverbascoside. Compounds 1 and 2 induced an estimated 2.7-fold increase in Ngn2 promoter activity, whereas 3 increased the activity by 2.5-fold. Furthermore, 1 and 2 enhanced neuronal differentiation of C17.2 cells, which are multipotent stem cells. PMID:26014045

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

    PubMed Central

    DCruz, Louise M; Knell, Jamie; Fujimoto, Jessica K; Goldrath, Ananda W

    2010-01-01

    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

  18. Oscillatory control of bHLH factors in neural progenitors.

    PubMed

    Imayoshi, Itaru; Kageyama, Ryoichiro

    2014-10-01

    The mammalian brain consists of a complex ensemble of neurons and glia. Their production during development and remodeling is tightly controlled by various regulatory mechanisms in neural progenitor cells (NPCs). Among such regulations, basic helix-loop-helix (bHLH) factors have key functions in the self-renewal, multipotency, and fate determination of NPCs. Here, we highlight the importance of the expression dynamics of bHLH factors in these processes. The oscillatory expression of multiple bHLH factors is correlated with the multipotent and self-renewable state, whereas sustained expression of a selected bHLH factor regulates fate determination. We also discuss potential mechanisms by which a single bHLH factor can exhibit versatile functions in NPC regulation as well as the hierarchical structure of the bHLH factor oscillatory network. PMID:25149265

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

    SciTech Connect

    Steen, Hakan; Lindholm, Dan

    2008-02-08

    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.

  20. Structural basis of nucleic acid recognition by FK506-binding protein 25 (FKBP25), a nuclear immunophilin

    PubMed Central

    Prakash, Ajit; Shin, Joon; Rajan, Sreekanth; Yoon, Ho Sup

    2016-01-01

    The nuclear immunophilin FKBP25 interacts with chromatin-related proteins and transcription factors and is suggested to interact with nucleic acids. Currently the structural basis of nucleic acid binding by FKBP25 is unknown. Here we determined the nuclear magnetic resonance (NMR) solution structure of full-length human FKBP25 and studied its interaction with DNA. The FKBP25 structure revealed that the N-terminal helix-loop-helix (HLH) domain and C-terminal FK506-binding domain (FKBD) interact with each other and that both of the domains are involved in DNA binding. The HLH domain forms major-groove interactions and the basic FKBD loop cooperates to form interactions with an adjacent minor-groove of DNA. The FKBP25–DNA complex model, supported by NMR and mutational studies, provides structural and mechanistic insights into the nuclear immunophilin-mediated nucleic acid recognition. PMID:26762975

  1. The genetics of rhizosheath size in a multiparent mapping population of wheat

    PubMed Central

    Delhaize, Emmanuel; Rathjen, Tina M.; Cavanagh, Colin R.

    2015-01-01

    Rhizosheaths comprise soil that adheres to plant roots and, in some species, are indicative of root hair length. In this study, the genetics of rhizosheath size in wheat was investigated by screening the progeny of multiparent advanced generation intercrosses (MAGIC). Two MAGIC populations were screened for rhizosheath size using a high throughput method. One MAGIC population was developed from intercrosses between four parents (4-way) and the other from intercrosses between eight parents (8-way). Transgressive segregation for rhizosheath size was observed in both the 4-way and 8-way MAGIC populations. A quantitative trait loci (QTL) analysis of the 4-way population identified six major loci located on chromosomes 2B, 4D, 5A, 5B, 6A, and 7A together accounting for 42% of the variation in rhizosheath size. Rhizosheath size was strongly correlated with root hair length and was robust across different soil types in the absence of chemical constraints. Rhizosheath size in the MAGIC populations was a reliable surrogate for root hair length and, therefore, the QTL identified probably control root hair elongation. Members of the basic helix-loop-helix family of transcription factors have previously been identified to regulate root hair length in Arabidopsis and rice. Since several wheat members of the basic helix-loop-helix family of genes are located within or near the QTL, these genes are candidates for controlling the long root hair trait. The QTL for rhizosheath size identified in this study provides the opportunity to implement marker-assisted selection to increase root hair length for improved phosphate acquisition in wheat. PMID:25969556

  2. Myogenin and MEF2 function synergistically to activate the MRF4 promoter during myogenesis.

    PubMed Central

    Naidu, P S; Ludolph, D C; To, R Q; Hinterberger, T J; Konieczny, S F

    1995-01-01

    The basic helix-loop-helix muscle regulatory factor (MRF) gene family encodes four distinct muscle-specific transcription factors known as MyoD, myogenin, Myf-5, and MRF4. These proteins represent key regulatory factors that control many aspects of skeletal myogenesis. Although the MRFs often exhibit overlapping functional activities, their distinct expression patterns during embryogenesis suggest that each protein plays a unique role in controlling aspects of muscle development. As a first step in determining how MRF4 gene expression is developmentally regulated, we examined the ability of the MRF4 gene to be expressed in a muscle-specific fashion in vitro. Our studies show that the proximal MRF4 promoter contains sufficient information to direct muscle-specific expression. Located within the proximal promoter are a single MEF2 site and E box that are required for maximum MRF4 expression. Mutation of the MEF2 site or E box severely impairs the ability of this promoter to produce a muscle-specific response. In addition, the MEF2 site and E box function in concert to synergistically activate the MRF4 gene in nonmuscle cells coexpressing MEF2 and myogenin proteins. Thus, the MRF4 promoter is regulated by the MEF2 and basic helix-loop-helix MRF protein family through a cross-regulatory circuitry. Surprisingly, the MRF4 promoter itself is not transactivated by MRF4, suggesting that this MRF gene is not subject to an autoregulatory pathway as previously implied by other studies. Understanding the molecular mechanisms regulating expression of each MRF gene is central to fully understanding how these factors control developmental events. PMID:7739551

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

    SciTech Connect

    Moffett, P.; Reece, M.; Pelletier, J.

    1996-07-01

    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.

  4. The E47 transcription factor binds to the enhancer sequences of recombinant murine leukemia viruses and influences enhancer function.

    PubMed

    Lawrenz-Smith, S C; Thomas, C Y

    1995-07-01

    The genomes of most recombinant murine leukemia viruses (MuLVs) inherit pathogenic U3 region sequences from the endogenous xenotropic provirus Bxv-1. However, the U3 regions of about one-third of recombinant MuLVs from CWD mice, such as CWM-T15, have nonecotropic substitutions that are probably derived from an endogenous polytropic provirus. The CWM-T15 U3 region sequences contain five nucleotide substitutions compared with the less pathogenic sequences of the endogenous ecotropic virus parent, Emv-1. Three of these substitutions are located immediately 3' of the enhancer core, and two form part of an E-box motif that is also found in the Bxv-1 sequence. A series of electromobility shift assays revealed that nuclear extracts from S194 cells and the basic helix-loop-helix transcription factor E47 could distinguish between oligonucleotides that contained the core region sequences of CWM-T15 or Emv-1. The E47 homodimers appeared to bind to the CWM-T15 E-box motif and when expressed at high levels in cells transactivated the CWM-T15 but not the Emv-1 enhancer. Taken together, these results suggest that E47 or related basic helix-loop-helix proteins that are expressed in lymphoid cells bind to and transactivate the CWM-T15 enhancer in vivo. This transactivation may explain why the CWM-T15 and Bxv-1 U3 regions accelerate the onset of lymphoid neoplasms and why related enhancer core region sequences are preferentially incorporated into the genomes of recombinant MuLVs and are found in other leukemogenic mammalian retroviruses. PMID:7769673

  5. Npas4 is activated by melatonin, and drives the clock gene Cry1 in the ovine pars tuberalis.

    PubMed

    West, A; Dupr, S M; Yu, L; Paton, I R; Miedzinska, K; McNeilly, A S; Davis, J R E; Burt, D W; Loudon, A S I

    2013-06-01

    Seasonal mammals integrate changes in the duration of nocturnal melatonin secretion to drive annual physiologic cycles. Melatonin receptors within the proximal pituitary region, the pars tuberalis (PT), are essential in regulating seasonal neuroendocrine responses. In the ovine PT, melatonin is known to influence acute changes in transcriptional dynamics coupled to the onset (dusk) and offset (dawn) of melatonin secretion, leading to a potential interval-timing mechanism capable of decoding changes in day length (photoperiod). Melatonin offset at dawn is linked to cAMP accumulation, which directly induces transcription of the clock gene Per1. The rise of melatonin at dusk induces a separate and distinct cohort, including the clock-regulated genes Cry1 and Nampt, but little is known of the up-stream mechanisms involved. Here, we used next-generation sequencing of the ovine PT transcriptome at melatonin onset and identified Npas4 as a rapidly induced basic helix-loop-helix Per-Arnt-Sim domain transcription factor. In vivo we show nuclear localization of NPAS4 protein in presumptive melatonin target cells of the PT (?-glycoprotein hormone-expressing cells), whereas in situ hybridization studies identified acute and transient expression in the PT of Npas4 in response to melatonin. In vitro, NPAS4 forms functional dimers with basic helix loop helix-PAS domain cofactors aryl hydrocarbon receptor nuclear translocator (ARNT), ARNT2, and ARNTL, transactivating both Cry1 and Nampt ovine promoter reporters. Using a combination of 5'-deletions and site-directed mutagenesis, we show NPAS4-ARNT transactivation to be codependent upon two conserved central midline elements within the Cry1 promoter. Our data thus reveal NPAS4 as a candidate immediate early-response gene in the ovine PT, driving molecular responses to melatonin. PMID:23598442

  6. Npas4 Is Activated by Melatonin, and Drives the Clock Gene Cry1 in the Ovine Pars Tuberalis

    PubMed Central

    West, A.; Dupr, S.M.; Yu, L.; Paton, I.R.; Miedzinska, K.; McNeilly, A.S.; Davis, J.R.E.

    2013-01-01

    Seasonal mammals integrate changes in the duration of nocturnal melatonin secretion to drive annual physiologic cycles. Melatonin receptors within the proximal pituitary region, the pars tuberalis (PT), are essential in regulating seasonal neuroendocrine responses. In the ovine PT, melatonin is known to influence acute changes in transcriptional dynamics coupled to the onset (dusk) and offset (dawn) of melatonin secretion, leading to a potential interval-timing mechanism capable of decoding changes in day length (photoperiod). Melatonin offset at dawn is linked to cAMP accumulation, which directly induces transcription of the clock gene Per1. The rise of melatonin at dusk induces a separate and distinct cohort, including the clock-regulated genes Cry1 and Nampt, but little is known of the up-stream mechanisms involved. Here, we used next-generation sequencing of the ovine PT transcriptome at melatonin onset and identified Npas4 as a rapidly induced basic helix-loop-helix Per-Arnt-Sim domain transcription factor. In vivo we show nuclear localization of NPAS4 protein in presumptive melatonin target cells of the PT (?-glycoprotein hormone-expressing cells), whereas in situ hybridization studies identified acute and transient expression in the PT of Npas4 in response to melatonin. In vitro, NPAS4 forms functional dimers with basic helix loop helix-PAS domain cofactors aryl hydrocarbon receptor nuclear translocator (ARNT), ARNT2, and ARNTL, transactivating both Cry1 and Nampt ovine promoter reporters. Using a combination of 5?-deletions and site-directed mutagenesis, we show NPAS4-ARNT transactivation to be codependent upon two conserved central midline elements within the Cry1 promoter. Our data thus reveal NPAS4 as a candidate immediate early-response gene in the ovine PT, driving molecular responses to melatonin. PMID:23598442

  7. The genetics of rhizosheath size in a multiparent mapping population of wheat.

    PubMed

    Delhaize, Emmanuel; Rathjen, Tina M; Cavanagh, Colin R

    2015-08-01

    Rhizosheaths comprise soil that adheres to plant roots and, in some species, are indicative of root hair length. In this study, the genetics of rhizosheath size in wheat was investigated by screening the progeny of multiparent advanced generation intercrosses (MAGIC). Two MAGIC populations were screened for rhizosheath size using a high throughput method. One MAGIC population was developed from intercrosses between four parents (4-way) and the other from intercrosses between eight parents (8-way). Transgressive segregation for rhizosheath size was observed in both the 4-way and 8-way MAGIC populations. A quantitative trait loci (QTL) analysis of the 4-way population identified six major loci located on chromosomes 2B, 4D, 5A, 5B, 6A, and 7A together accounting for 42% of the variation in rhizosheath size. Rhizosheath size was strongly correlated with root hair length and was robust across different soil types in the absence of chemical constraints. Rhizosheath size in the MAGIC populations was a reliable surrogate for root hair length and, therefore, the QTL identified probably control root hair elongation. Members of the basic helix-loop-helix family of transcription factors have previously been identified to regulate root hair length in Arabidopsis and rice. Since several wheat members of the basic helix-loop-helix family of genes are located within or near the QTL, these genes are candidates for controlling the long root hair trait. The QTL for rhizosheath size identified in this study provides the opportunity to implement marker-assisted selection to increase root hair length for improved phosphate acquisition in wheat. PMID:25969556

  8. Sunspace basics

    SciTech Connect

    Not Available

    1994-11-01

    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.

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

    PubMed Central

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

    2013-01-01

    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

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

    PubMed Central

    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

    2014-01-01

    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

  11. Functional characterization of PAS and HES family bHLH transcription factors during the metamorphosis of the red flour beetle, Tribolium castaneum

    PubMed Central

    Bitra, Kavita; Tan, Anjiang; Dowling, Ashley; Palli, Subba R.

    2009-01-01

    The basic helix-loop-helix transcription factors are present in animals, plants and fungi and play important roles in the control of cellular proliferation, tissue differentiation, development and detoxification. Although insect genomes contain more than 50 Helix-Loop-Helix transcription factors, the functions of only a few are known. RNAi has become a widely used tool to knockdown the expression to analyze the function of genes. As RNAi works well in Tribolium castaneum, we utilized this insect and RNAi to determine functions of 19 bHLH transcription factors belonging to PAS and HES families during the larval stages of the red flour beetle, T. castaneum. We searched the genome sequence of T. castaneum and identified 53 bHLH genes. Phylogenetic analyses classified these 53 genes into ten families; PAS, HES, Myc/USF, Hand, Mesp, Shout, p48, NeuroD/Neurogenin, Atonal and AS-C. In RNAi studies, knocking-down the expression of seven members of the PAS and HES families affected the growth and development of T. castaneum. An inability to grow to reach critical weight to undergo metamorphosis, failure to complete larval-pupal or pupal-adult ecdysis and abnormal wing development are among the most common phenotypes observed in RNAi insects. Among the bHLH transcription factors studied, the steroid receptor coactivator (SRC) showed the most severe phenotypes. Knock-down in the expression of the gene coding for SRC caused growth arrest by affecting the regulation of lipid metabolism. These studies demonstrate the power of RNAi for functional characterization of members of the multigene families in this model insect. PMID:19683038

  12. DNA topoisomerase I affects polycomb group protein-mediated epigenetic regulation and plant development by altering nucleosome distribution in Arabidopsis.

    PubMed

    Liu, Xigang; Gao, Lei; Dinh, Thanh Theresa; Shi, Ting; Li, Dongming; Wang, Ruozhong; Guo, Lin; Xiao, Langtao; Chen, Xuemei

    2014-07-01

    It has been perplexing that DNA topoisomerases, enzymes that release DNA supercoils, play specific roles in development. In this study, using a floral stem cell model in Arabidopsis thaliana, we uncovered a role for TOPOISOMERASE1α (TOP1α) in Polycomb Group (PcG) protein-mediated histone 3 lysine 27 trimethylation (H3K27me3) at, and transcriptional repression of, the stem cell maintenance gene WUSCHEL (WUS). We demonstrated that H3K27me3 deposition at other PcG targets also requires TOP1α. Intriguingly, the repression of some, as well as the expression of many, PcG target genes requires TOP1α. The mechanism that unifies the opposing effects of TOP1α appears to lie in its role in decreasing nucleosome density, which probably allows the binding of factors that either recruit PcG, as we demonstrated for AGAMOUS at the WUS locus, or counteract PcG-mediated regulation. Although TOP1α reduces nucleosome density at all genes, the lack of a 5' nucleosome-free region is a feature that distinguishes PcG targets from nontargets and may condition the requirement for TOP1α for their expression. This study uncovers a connection between TOP1α and PcG, which explains the specific developmental functions of TOP1α. PMID:25070639

  13. Protein mediated membrane adhesion

    NASA Astrophysics Data System (ADS)

    Carlson, Andreas; Mahadevan, L.

    2015-05-01

    Adhesion in the context of mechanical attachment, signaling, and movement in cellular dynamics is mediated by the kinetic interactions between membrane-embedded proteins in an aqueous environment. Here, we present a minimal theoretical framework for the dynamics of membrane adhesion that accounts for the kinetics of protein binding, the elastic deformation of the membrane, and the hydrodynamics of squeeze flow in the membrane gap. We analyze the resulting equations using scaling estimates to characterize the spatiotemporal features of the adhesive patterning and corroborate them using numerical simulations. In addition to characterizing aspects of cellular dynamics, our results might also be applicable to a range of phenomena in physical chemistry and materials science where flow, deformation, and kinetics are coupled to each other in slender geometries.

  14. Alcohol oxidase protein mediated in-situ synthesized and stabilized gold nanoparticles for developing amperometric alcohol biosensor.

    PubMed

    Chinnadayyala, Somasekhar R; Santhosh, Mallesh; Singh, Naveen K; Goswami, Pranab

    2015-07-15

    A simple one step method for the alcohol oxidases (AOx) protein mediated synthesis of gold nano-particles (AuNPs) in alkaline (pH 8.5) condition with simultaneous stabilization of the nanoparticles on the AOx protein surface under native environment has been developed. The formation of the AOx conjugated AuNPs was confirmed by advanced analytical and spectroscopic techniques. The significant increase in zeta potential (ζ) value of -57mV for the synthesized AOx-AuNPs conjugate from the AOx (pI 4.5) protein (ζ, -30mV) implied good stability of the in-situ synthesized nano-conjugate. The AOx-AuNPs conjugate showed steady stability in alkaline (upto pH 8.5) and NaCl (up to 10(-1)M) solutions. The efficiency (Kcat/Km) of the AuNP conjugated AOx was increased by 18% from the free enzyme confirming the activating role of the surface stabilized AuNPs for the enzyme. The AuNPs-AOx conjugate was encapsulated with polyaniline (PANI) synthesized by oxidative polymerization of aniline using H2O2 generated in-situ from the AOx catalysed oxidation of alcohol. The PANI encapsulated AuNPs-AOx assembly was stabilized on a glassy carbon electrode (GCE) by chitosan-Nafion mixture and then utilized the fabricated bioelectrode for detection of alcohol amperometrically using H2O2 as redox indicator at +0.6V. The constructed biosensor showed high operational stability (6.3% loss after 25 measurements), wide linear detection range of 10µM-4.7mM (R(2)=0.9731), high sensitivity of 68.3±0.35µAmM(-1) and low detection limit of 7±0.027µM for ethanol. The fabricated bioelectrode was successfully used for the selective determination of alcohol in beverage samples. PMID:25725464

  15. Stem Cell Basics

    MedlinePlus

    ... Information Stem Cell Basics Stem Cell Basics: Introduction Stem Cell Information General Information Clinical Trials Funding Information Current Research Policy Glossary Site Map Stem Cell Basics Introduction: What are stem cells, and why ...

  16. Stem Cell Basics

    MedlinePlus

    ... General Information Stem Cell Basics Stem Cell Basics Stem Cell Information General Information Clinical Trials Funding Information Current Research Policy Glossary Site Map Stem Cell Basics This primer on stem cells is intended ...

  17. Basics of SCI Rehabilitation

    MedlinePlus

    Experts \\ The Basics of Spinal Cord Injury Rehabilitation Topics Adult Injuries Spinal Cord Injury 101 Spinal Cord Injury 101 The Basics of Spinal Cord Injury Rehabilitation The Basics of Spinal Cord ...

  18. Adult Basic Education Basic Computer Literacy Handbook.

    ERIC Educational Resources Information Center

    Manini, Catalina M.; Cervantes, Juan

    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

  19. The Gαi AND Gαq Proteins Mediate the Effects of Melatonin on Steroid/Thyroid Hormone Receptor Transcriptional Activity and Breast Cancer Cell Proliferation

    PubMed Central

    Lai, Ling; Yuan, Lin; Chen, Qi; Dong, Chunmin; Mao, Lulu; Rowan, Brian; Frasch, Tripp; Hill, Steven M.

    2016-01-01

    Melatonin, via its MT1 receptor, but not the MT2 receptor, can modulate the transcriptional activity of various nuclear receptors (ERα and RARα, but not ERβ) in MCF-7, T47D and ZR-75-1 human breast cancer cell lines. The anti-proliferative and nuclear receptor modulatory actions of melatonin are mediated via the MT1 G protein-coupled receptor expressed in human breast cancer cells. However, the specific G proteins and associated pathways involved in nuclear receptor transcriptional regulation by melatonin are not yet clear. Upon activation, the MT1 receptor specifically couples to the Gαi2, Gαi3, Gαq and Gαll proteins, and via activation of Gαi2 proteins, melatonin suppresses forskolin-induced cyclic AMP (cAMP) production, while melatonin activation of Gαq, is able to inhibit phospholipid hydrolysis and ATP’s induction of inositol triphosphate (IP3) production in MCF-7 breast cancer cells. Employing dominant-negative (DN) and dominant-positive (DP) forms of these G proteins we demonstrate that Gαi2 proteins mediate the suppression of estrogen-induced ERα transcriptional activity by melatonin, while the Gq protein mediates the enhancement of retinoid-induced RARα transcriptional activity by melatonin. However, the growth-inhibitory actions of melatonin are mediated via both Gαi2 and Gαq proteins. PMID:18705646

  20. PASCAL vs BASIC

    ERIC Educational Resources Information Center

    Mundie, David A.

    1978-01-01

    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)

  1. Health Insurance Basics

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Health Insurance Basics KidsHealth > For Teens > Health Insurance Basics Print ... thought advanced calculus was confusing. What Exactly Is Health Insurance? Health insurance is a plan that people buy ...

  2. Basic Cake Decorating Workbook.

    ERIC Educational Resources Information Center

    Bogdany, Mel

    Included in this student workbook for basic cake decorating are the following: (1) Drawings of steps in a basic way to ice a layer cake, how to make a paper cone, various sizes of flower nails, various sizes and types of tin pastry tubes, and special rose tubes; (2) recipes for basic decorating icings (buttercream, rose paste, and royal icing);…

  3. Body Basics Library

    MedlinePlus

    ... a Friend Who Cuts? About the Body Basics Library KidsHealth > For Teens > About the Body Basics Library Print A A A Text Size Did you ... system, part, and process works. Use this medical library to find out about basic human anatomy, how ...

  4. Basic Cake Decorating Workbook.

    ERIC Educational Resources Information Center

    Bogdany, Mel

    Included in this student workbook for basic cake decorating are the following: (1) Drawings of steps in a basic way to ice a layer cake, how to make a paper cone, various sizes of flower nails, various sizes and types of tin pastry tubes, and special rose tubes; (2) recipes for basic decorating icings (buttercream, rose paste, and royal icing);

  5. CSF myelin basic protein

    MedlinePlus

    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. Normal value ranges may vary ...

  6. Exponentiation: A New Basic?

    ERIC Educational Resources Information Center

    Davis, Brent

    2015-01-01

    For centuries, the basic operations of school mathematics have been identified as addition, subtraction, multiplication, and division. Notably, these operations are "basic," not because they are foundational to mathematics knowledge, but because they were vital to a newly industrialized and market-driven economy several hundred years…

  7. Fluency with Basic Addition

    ERIC Educational Resources Information Center

    Garza-Kling, Gina

    2011-01-01

    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

  8. Romanian Basic Course.

    ERIC Educational Resources Information Center

    Defense Language Inst., Washington, DC.

    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…

  9. BASIC Beats PASCAL.

    ERIC Educational Resources Information Center

    Ever, Jacob

    1981-01-01

    Features of two versions of the BASIC programing language are compared with the features of the PASCAL programing language. The application chosen for comparison was a word processor. The conclusion was that PASCAL had the best language features, but BASIC had better systems capabilities. (MP)

  10. Fluency with Basic Addition

    ERIC Educational Resources Information Center

    Garza-Kling, Gina

    2011-01-01

    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…

  11. Exponentiation: A New Basic?

    ERIC Educational Resources Information Center

    Davis, Brent

    2015-01-01

    For centuries, the basic operations of school mathematics have been identified as addition, subtraction, multiplication, and division. Notably, these operations are "basic," not because they are foundational to mathematics knowledge, but because they were vital to a newly industrialized and market-driven economy several hundred years

  12. Basic Science Training Program.

    ERIC Educational Resources Information Center

    Brummel, Clete

    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…

  13. Basic Electronics I.

    ERIC Educational Resources Information Center

    Robertson, L. Paul

    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…

  14. From basic needs to basic rights.

    PubMed

    Facio, A

    1995-06-01

    After arriving at an understanding that basic rights refer to all human needs, it is clear that a recognition of the basic needs of female humans must precede the realization of their rights. The old Women in Development (WID) framework only understood women's needs from an androcentric perspective which was limited to practical interests. Instead, women's primary need is to be free from their subordination to men. Such an understanding places all of women's immediate needs in a new light. A human rights approach to development would see women not as beneficiaries but as people entitled to enjoy the benefits of development. Discussion of what equality before the law should mean to women began at the Third World Conference on Women in Nairobi where the issue of violence against women was first linked to development. While debate continues about the distinction between civil and political rights and economic, social, and cultural rights, the realities of women's lives do not permit such a distinction. The concept of the universality of human rights did not become codified until the UN proclaimed the Universal Declaration of Human Rights in 1948. The declaration has been criticized by feminists because the view of human rights it embodies has been too strongly influenced by a liberal Western philosophy which stresses individual rights and because it is ambiguous on the distinction between human rights and the rights of a citizen. The protection of rights afforded by the Declaration, however, should not be viewed as a final achievement but as an ongoing struggle. International conferences have led to an analysis of the human-rights approach to sustainable development which concludes that women continue to face the routine denial of their rights. Each human right must be redefined from the perspective of women's needs, which must also be redefined. Women must forego challenging the concept of the universality of human rights in order to overcome the argument of cultural and religious diversity which erodes women's rights. Women can, however, challenge the traditional patriarchal understanding of human rights, drawing on the energy contained in the "basic needs to basic rights" approach. PMID:12290121

  15. Basic Emotions: A Rejoinder

    PubMed Central

    Mason, William A.; Capitanio, John P.

    2016-01-01

    A principal theme of our article is that emotions, including what are called basic emotions, cannot be exhaustively categorized as “innate” or “acquired.” Instead, we argue that basic emotions are more realistically viewed as emergent phenomena, the result of complex interrelations of environmental and organismic factors at all levels of organization. While the commentators apparently accepted the proposed developmental paradigm, they took exception to aspects of our treatment of basic emotions and made a number of helpful comments, to which we respond below.

  16. Role of arabidopsis MYC and MYB homologs in drought- and abscisic acid-regulated gene expression.

    PubMed Central

    Abe, H; Yamaguchi-Shinozaki, K; Urao, T; Iwasaki, T; Hosokawa, D; Shinozaki, K

    1997-01-01

    In Arabidopsis, the induction of a dehydration-responsive gene, rd22, is mediated by abscisic acid (ABA) and requires protein biosynthesis for ABA-dependent gene expression. Previous experiments established that a 67-bp DNA fragment of the rd22 promoter is sufficient for dehydration- and ABA-induced gene expression and that this DNA fragment contains two closely located putative recognition sites for the basic helix-loop-helix protein MYC and one putative recognition site for MYB. We have carefully analyzed the 67-bp region of the rd22 promoter in transgenic tobacco plants and found that both the first MYC site and the MYB recognition site function as cis-acting elements in the dehydration-induced expression of the rd22 gene. A cDNA encoding a MYC-related DNA binding protein was isolated by DNA-ligand binding screening, using the 67-bp region as a probe, and designated rd22BP1. The rd22BP1 cDNA encodes a 68-kD protein that has a typical DNA binding domain of a basic region helix-loop-helix leucine zipper motif in MYC-related transcription factors. The rd22BP1 protein binds specifically to the first MYC recognition site in the 67-bp fragment. RNA gel blot analysis revealed that transcription of the rd22BP1 gene is induced by dehydration stress and ABA treatment, and its induction precedes that of rd22. We have reported a drought- and ABA-inducible gene that encodes the MYB-related protein ATMYB2. In a transient transactivation experiment using Arabidopsis leaf protoplasts, we demonstrated that both the rd22BP1 and ATMYB2 proteins activate transcription of the rd22 promoter fused to the beta-glucuronidase reporter gene. These results indicate that both the rd22BP1 (MYC) and ATMYB2 (MYB) proteins function as transcriptional activators in the dehydration- and ABA-inducible expression of the rd22 gene. PMID:9368419

  17. Basics of Frontotemporal Disorders

    MedlinePlus

    ... 23 MB) Order Share this: ​ Table of Contents Introduction The Basics of Frontotemporal Disorders Types of Frontotemporal Disorders Causes Diagnosis Common Symptoms Treatment and Management Caring for a Person with a Frontotemporal Disorder ...

  18. Comparison of Basics.

    ERIC Educational Resources Information Center

    Creative Computing, 1981

    1981-01-01

    Presented is a chart which compares the nature of the BASIC programing languages found with the following systems: Atari, Apple Integer, Applesoft, Exidy, TRS 80 Level I, TRS 80 Level II, TRS 80 DOS, and PET. (MP)

  19. Basics of Dusty Plasma

    SciTech Connect

    Ignatov, A.M.

    2005-01-15

    The paper presents an introductory review of the basic physical processes in dusty plasmas. The topics to be addressed are dust charging, forces acting on dust grains, interaction between dust grains, and dust-plasma structures.

  20. Video Screen Capture Basics

    ERIC Educational Resources Information Center

    Dunbar, Laura

    2014-01-01

    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.

  1. HIV Treatment: The Basics

    MedlinePlus

    HIV Treatment HIV Treatment: The Basics (Last updated 3/1/2016; last reviewed 3/1/2016) Key Points Antiretroviral therapy (ART) ... reduces the risk of HIV transmission . How do HIV medicines work? HIV attacks and destroys the infection- ...

  2. Basics of cosmic structures

    NASA Astrophysics Data System (ADS)

    Celnikier, Ludwik M.

    The universe is examined from the viewpoint of an engineer who uses the laws of physics, reduced to their most basic forms, as tools to study a wide variety of cosmic structures, ranging from atomic nuclei to planets, stars, and black holes. The basic structures of the universe are examined, including electromagnetic structures, solid and liquid matter, and exotic materials. The structure of stars and their structural limits are addressed. Cosmic environments including atmospheres, ionized envelopes, gravitational environments, and cosmic engines are examined.

  3. Protein-mediated layer-by-layer synthesis of TiO₂(B)/anatase/carbon coating on nickel foam as negative electrode material for lithium-ion battery.

    PubMed

    Wang, Xiaobo; Yan, Yong; Hao, Bo; Chen, Ge

    2013-05-01

    Through an aqueous, protein-mediated layer-by-layer titania deposition process, we have fabricated a protamine/titania composite layer on nickel foam. The coating was composed of amorphous carbon and TiO2(B)/anatase nanoparticles and formed upon organic pyrolysis under a reducing atmosphere (5% H2-Ar mixture). X-ray diffraction analyses, Auger electron spectroscopy, and high-resolution transmission electron microscopy revealed that the obtained coatings contained fine monoclinic TiO2(B) and anatase nanocrystals, along with amorphous carbon. Moreover, the coating can be used as a binder-free negative electrode material for lithium-ion batteries and exhibits high reversible capacity and fast charge-discharge properties; a reversible capacity of 245 mAh g(-1) was obtained at a current density of 50 mA g(-1), and capacities of 167 and 143 mAh g(-1) were obtained at current densities of 1 and 2 A g(-1), respectively. PMID:23597025

  4. Protein-mediated adhesion of the dissimilatory Fe(III)-reducing bacterium Shewanella alga BrY to hydrous ferric oxide

    SciTech Connect

    Caccavo, F. Jr.

    1999-11-01

    The rate and extent of bacterial Fe(III) mineral reduction are governed by molecular-scale interactions between the bacterial cell surface and the mineral surface. These interactions are poorly understood. This study examined the role of surface proteins in the adhesion of Shewanella alga BrY to hydrous ferric oxide (HFO). Enzymatic degradation of cell surface polysaccharides had no effect on cell adhesion to HFO. The proteolytic enzymes Streptomyces griseus protease and chymotrypsin inhibited the adhesion of S. alga BrY cells to HFO through catalytic degradation of surface proteins. Trypsin inhibited S. alga BrY adhesion solely through surface-coating effects. Protease and chymotrypsin also mediated desorption of adhered S. alga BrY cells from HFO while trypsin did not mediate cell desorption. Protease removed a single peptide band that represented a protein with an apparent molecular mass of 50 kDa. Chymotrypsin removed two peptide bands that represented proteins with apparent molecular masses of 60 and 31 kDa. These proteins represent putative HGO adhesion molecules. A. alga BrY adhesion was inhibited by up to 46% when cells were cultured at sub-MICs of chloramphenicol, suggesting that protein synthesis is necessary for adhesion. Proteins extracted from the surface of S. alga BrY cells inhibited adhesion to HFO by up to 41%. A number of these proteins bound specifically to HFO, suggesting that a complex system of surface proteins mediates S. alga BrY adhesion to HFO.

  5. Protein secretion in gram-negative bacteria: assembly of the three components of ABC protein-mediated exporters is ordered and promoted by substrate binding.

    PubMed Central

    Létoffé, S; Delepelaire, P; Wandersman, C

    1996-01-01

    One of the strategies used by Gram-negative bacteria to secrete proteins across the two membranes which delimit the cells, is sec independent and dedicated to proteins lacking an N-terminal signal peptide. It depends on ABC protein-mediated exporters, which consist of three cell envelope proteins, two inner membrane proteins, an ATPase (the ABC protein), a membrane fusion protein (MFP) and an outer membrane polypeptide. Erwinia chrysanthemi metalloproteases B and C and Serratia marcescens hemoprotein HasA are secreted by such homologous pathways and interact with the ABC protein. Using as protein substrates HasA and GST-PrtC, a chimeric protein which has a glutathione S-transferase moiety fused to a large C-terminal domain of protease C, we developed a simple system to identify proteins bound to the substrate based on substrate affinity-chromatography using heme- or glutathione-agarose. We show an ordered association between the protein substrates and the three exporter components: the substrate recognizes the ABC protein which interacts with the MFP which in turn binds the outer membrane component. Substrate binding is required for assembly of the three components. Images PMID:8918458

  6. Gq protein mediates UVB-induced cyclooxygenase-2 expression by stimulating HB-EGF secretion from HaCaT human keratinocytes

    SciTech Connect

    Seo, MiRan; Juhnn, Yong-Sung

    2010-03-05

    Ultraviolet (UV) radiation induces cyclooxygenase-2 expression to produce cellular responses including aging and carcinogenesis in skin. We hypothesised that heterotrimeric G proteins mediate UV-induced COX-2 expression by stimulating secretion of soluble HB-EGF (sHB-EGF). In this study, we aimed to elucidate the role and underlying mechanism of the {alpha} subunit of Gq protein (G{alpha}q) in UVB-induced HB-EGF secretion and COX-2 induction. We found that expression of constitutively active G{alpha}q (G{alpha}qQL) augmented UVB-induced HB-EGF secretion, which was abolished by knockdown of G{alpha}q with shRNA in HaCaT human keratinocytes. G{alpha}q was found to mediate the UVB-induced HB-EGF secretion by sequential activation of phospholipase C (PLC), protein kinase C{delta} (PKC{delta}), and matrix metaloprotease-2 (MMP-2). Moreover, G{alpha}qQL mediated UVB-induced COX-2 expression in an HB-EGF-, EGFR-, and p38-dependent manner. From these results, we concluded that G{alpha}q mediates UV-induced COX-2 expression through activation of EGFR by HB-EGF, of which ectodomain shedding was stimulated through sequential activation of PLC, PKC{delta} and MMP-2 in HaCaT cells.

  7. Basic research championed

    NASA Astrophysics Data System (ADS)

    Friebele, Elaine

    In April, the Office of National Science and Technology Policy released its biennial report to Congress. Science and Technology: Shaping the Twenty-First Century addresses the President's policy for maintaining U.S. leadership in science and technology, significant developments, and important national issues in science, and opportunities to use science and technology in federal programs and national goals. The administration strongly supports basic research as a sound investment and an inspiration to society. As corporate laboratories increasingly favor applied R&D projects, the federal government is becoming the dominant sponsor of long-term, basic research.

  8. Basic Electronics II.

    ERIC Educational Resources Information Center

    Willison, Neal A.; Shelton, James K.

    Designed for use in basic electronics programs, this curriculum guide is comprised of 15 units of instruction. Unit titles are Review of the Nature of Matter and the P-N Junction, Rectifiers, Filters, Special Semiconductor Diodes, Bipolar-Junction Diodes, Bipolar Transistor Circuits, Transistor Amplifiers, Operational Amplifiers, Logic Devices,…

  9. Projectable Basic Electronics Kit.

    ERIC Educational Resources Information Center

    H'ng, John; And Others

    1982-01-01

    Outlines advantages derived from constructing and using a Projectable Basic Electronics Kit and provides: (1) list of components; (2) diagrams of 10 finished components (resistor; capacitor; diode; switch; bulb; transistor; meter; variable capacitor; coil; connecting terminal); and (3) diode and transistor activities. (JN)

  10. Microeconomic Analysis with BASIC.

    ERIC Educational Resources Information Center

    Tom, C. F. Joseph

    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.…

  11. Swahili Basic Course.

    ERIC Educational Resources Information Center

    Defense Language Inst., Washington, DC.

    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…

  12. Basic Structure of Swahili.

    ERIC Educational Resources Information Center

    Brain, James L.

    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…

  13. Czech Basic Course: Folklore.

    ERIC Educational Resources Information Center

    Defense Language Inst., Washington, DC.

    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…

  14. FULA BASIC COURSE.

    ERIC Educational Resources Information Center

    SWIFT, LLOYD B.; AND OTHERS

    THIS BEGINNING COURSE IS AN INTRODUCTION TO FULA (KNOWN VARIOUSLY AS FULANI, FUL, PEUL, OR PHEUL), A NIGER-CONGO LANGUAGE SPOKEN THROUGHOUT THE GRASSLAND AREAS OF WEST AFRICA FROM THE ATLANTIC TO CAMEROUN. THE TEXT IS ONE OF A SERIES OF SHORT BASIC COURSES IN SELECTED AFRICAN LANGUAGES BEING PREPARED BY THE FOREIGN SERVICE INSTITUTE. IT IS…

  15. Basic Media in Education.

    ERIC Educational Resources Information Center

    Harrell, John

    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

  16. Reflections on basic science.

    PubMed

    Piatigorsky, Joram

    2010-01-01

    After almost 50 years in science, I believe that there is an acceptable, often advantageous chasm between open-ended basic research-free exploration without a practical destination and in which the original ideas may fade into new concepts-and translational research or clinical research. My basic research on crystalline (proteins conferring the optical properties of the eye lens) led me down paths I never would have considered if I were conducting translational research. My investigations ranged from jellyfish to mice and resulted in the gene-sharing concept, which showed that the same protein can have distinct molecular functions depending upon its expression pattern and, conversely, that different proteins can serve similar functional roles. This essay portrays basic science as a creative narrative, comparable to literary and artistic endeavors. Preserving the autonomy of open-ended basic research and recognizing its artistic, narrative qualities will accelerate the development of innovative concepts, create a rich resource of information feeding translational research, and have a positive impact by attracting creative individuals to science. PMID:21037410

  17. Focus on Basics, 1997.

    ERIC Educational Resources Information Center

    Focus on Basics, 1997

    1997-01-01

    Together, these four newsletters contain 36 articles devoted to adult literacy research and practice and the relationship between them. The following articles are included: "A Productive Partnership" (Richard J. Murnane, Bob Bickerton); "Welcome to 'Focus on Basics'" (Barbara Garner); "Applying Research on the Last Frontier" (Karen Backlund, Kathy…

  18. Hindi Basic Reader.

    ERIC Educational Resources Information Center

    Harter, J. Martin; And Others

    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)

  19. Basic Electricity. Part 1.

    ERIC Educational Resources Information Center

    Kilmer, Donald C.

    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…

  20. Basic Skills Assessment

    ERIC Educational Resources Information Center

    Yin, Alexander C.; Volkwein, J. Fredericks

    2010-01-01

    After surveying 1,827 students in their final year at eighty randomly selected two-year and four-year public and private institutions, American Institutes for Research (2006) reported that approximately 30 percent of students in two-year institutions and nearly 20 percent of students in four-year institutions have only basic quantitative…

  1. Greek Basic Course.

    ERIC Educational Resources Information Center

    Defense Language Inst., Washington, DC.

    This course in Modern Greek, consisting of 100 lesson units in 13 volumes, is one of the Defense Language Institute's Basic Course Series. The course is designed to train native English language speakers to Level 3 proficiency in comprehension, speaking, reading, and writing Modern Greek. (Level 5 is native-speaker proficiency.) Lesson units…

  2. Basic Nuclear Physics.

    ERIC Educational Resources Information Center

    Bureau of Naval Personnel, Washington, DC.

    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…

  3. Developing Basic Electronics Aptitudes.

    ERIC Educational Resources Information Center

    Lakeshore Technical Coll., Cleveland, WI.

    This curriculum guide provides materials for basic training in electrical and electronic theory to enable participants to analyze circuits and use test equipment to verify electrical operations and to succeed in the beginning electrical and electronic courses in the Lakeshore Technical College (Wisconsin) electronics programs. The course includes…

  4. Basic Experiments in Telecommunications.

    ERIC Educational Resources Information Center

    Andresen, S. G.

    Presented is a set of laboratory experiments developed to provide students with demonstrations and hands-on experiences with a variety of basic communications methods. These experiments may be used with students who have training in engineering, as well as those with social sciences who have no engineering background. Detailed exercises dealing…

  5. Basic Pneumatics. Instructor's Guide.

    ERIC Educational Resources Information Center

    Fessehaye, Michael

    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;…

  6. Turkish Basic Course.

    ERIC Educational Resources Information Center

    Defense Language Inst., Washington, DC.

    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…

  7. Basic Drafting: Book One.

    ERIC Educational Resources Information Center

    Davis, Ronald; And Others

    The first of a two-book course in drafting, this manual consists of 13 topics in the following units: introduction to drafting, general safety, basic tools and lines, major equipment, applying for a job, media, lettering, reproduction, drawing sheet layout, architect's scale usage, civil engineer's scale usage, mechanical engineer's scale usage,…

  8. Reading for Basic Understanding.

    ERIC Educational Resources Information Center

    Mercer County Community Coll., Trenton, NJ.

    This document offers materials for a year-long course on general basic reading skills that was part of a workplace literacy project developed by Mercer County Community College (New Jersey), and its partners. The document contains the following: (1) outlines (each of which contains objectives, a topical outline, and list of textbooks) for two…

  9. Ethanol Basics (Fact Sheet)

    SciTech Connect

    Not Available

    2015-01-01

    Ethanol is a widely-used, domestically-produced renewable fuel made from corn and other plant materials. More than 96% of gasoline sold in the United States contains ethanol. Learn more about this alternative fuel in the Ethanol Basics Fact Sheet, produced by the U.S. Department of Energy's Clean Cities program.

  10. Precompound Reactions: Basic Concepts

    SciTech Connect

    Weidenmueller, H. A.

    2008-04-17

    Because of the non-zero nuclear equilibration time, the compound-nucleus scattering model fails when the incident energy exceeds 10 or 20 MeV, and precompound reactions become important. Basic ideas used in the quantum-statistical approaches to these reactions are described.

  11. Basic Engineer Equipment Mechanic.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    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…

  12. Focus on Basics, 1998.

    ERIC Educational Resources Information Center

    Focus on Basics, 1998

    1998-01-01

    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,…

  13. The Techno-Basics.

    ERIC Educational Resources Information Center

    West, Philip T.

    1983-01-01

    Education's effective utilization of electronic technology--especially microcomputers and wall-sized, interactive television--will require emphasizing five "techno-basic" skills, including computing, perceiving (comprehending what one sees), auditing (developing appropriate listening skills), articulating (presenting messages through television),…

  14. Basics of Online Searching.

    ERIC Educational Resources Information Center

    Meadow, Charles T.; Cochrane, Pauline (Atherton)

    Intended to teach the principles of interactive bibliographic searching to those with little or no prior experience, this textbook explains the basic elements of online information retrieval and compares the major database search systems. Its chapters address (1) relevant definitions and vocabulary; (2) the conceptual facets of database searching,…

  15. Assessing Basic Fact Fluency

    ERIC Educational Resources Information Center

    Kling, Gina; Bay-Williams, Jennifer M.

    2014-01-01

    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,…

  16. Basic Skills: Visual Arts.

    ERIC Educational Resources Information Center

    Kentucky State Dept. of Education, Frankfort.

    A curriculum guide for the visual arts is presented. The goal of elementary and middle school education in the four arts disciplines is the development of basic understanding and skills by every student. In secondary education the aim is to continue a sequential curriculum for those students who study the arts. This document is intended as a guide…

  17. Basic Skills Packet.

    ERIC Educational Resources Information Center

    Smith, Geoffrey

    The document describes the basic skills programs in reading and mathematics of the High School in the Community (HSC) in New Haven, Connecticut. HSC, designed to provide a choice of learning environments within the public school system, serves students dissatisfied with their previous school experience. Each student, on entering HSC, is screened…

  18. Literacy: Democracy's Basic Ingredient.

    ERIC Educational Resources Information Center

    Chisholm, Shirley

    1988-01-01

    Indicates that literacy skills are basic to the survival of a democratic society. Discusses reading as an empowerment tool for allowing people to participate in the democratic process and stresses the relationship of the educational and political establishment to a literate society and between literacy and social equality. (Author/JOW)

  19. Chest Pain (Beyond the Basics)

    MedlinePlus

    ... pancreatitis, and irritable bowel syndrome. (See "Patient information: Peptic ulcer disease (Beyond the Basics)" and "Patient information: Acute ... disease) in adults (Beyond the Basics) Patient information: Peptic ulcer disease (Beyond the Basics) Patient information: Acute pancreatitis ( ...

  20. DEC1 negatively regulates AMPK activity via LKB1

    PubMed Central

    Sato, Fuyuki; Muragaki, Yasuteru; Zhang, Yanping

    2016-01-01

    Basic helix-loop-helix (bHLH) transcription factor DEC1 (bHLHE40/Stra13/Sharp2) is one of the clock genes that show a circadian rhythm in various tissues. AMP-activated protein kinase (AMPK) activity plays important roles in the metabolic process and in cell death induced by glucose depletion. Recent reports have shown that AMPK activity exhibited a circadian rhythm. However, little is known regarding the regulatory mechanisms involved in the circadian rhythm of AMPK activity. The aim of this study is to investigate whether there is a direct correlation between DEC1 expression and AMPK activity. DEC1 protein and AMPK activity showed a circadian rhythm in the mouse liver with different peak levels. Knocking down DEC1 expression increased AMPK activity, whereas overexpression of DEC1 decreased it. Overexpressing the DEC1 basic mutants had little effect on the AMPK activity. DEC1 bound to the E-box of the LKB1 promoter, decreased LKB1 activity and total protein levels. There was an inverse relationship between DEC1 expression and AMPK activity. Our results suggest that DEC1 negatively regulates AMPK activity via LKB1. PMID:26498531

  1. 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.

    PubMed

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

    2015-12-01

    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

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

    PubMed Central

    Prendergast, G C; Ziff, E B

    1991-01-01

    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

  3. A transcription factor controlling development of peripheral sense organs in C. elegans.

    PubMed

    Zhao, C; Emmons, S W

    1995-01-01

    The basic-helix-loop-helix (bHLH) proteins constitute a class of transcription factors thought to be important in the control of cell-type determination. These transcription factors are believed to activate the expression of cell-type-specific genes to generate stable differentiated cell types. The expression of bHLH proteins, in turn, is regulated by spatial cues, so that switches in cell type occur in a reproducible pattern. We report here that the lin-32 gene of Caenorhabditis elegans, which encodes a bHLH protein of the Drosophila achaete-scute family of transcription factors, is necessary and in some cells sufficient for specification of the neuroblast cell fate. Similarity in the function and structure of the lin-32 protein (LIN-32) to transcription factors of the achaete-scute gene family in Drosophila and vertebrates implies that this class of transcription factors functioned in a primitive ancestral form to specify neuronal cell fate, supporting the proposition that certain basic mechanisms of cell-type determination have been conserved through metazoan evolution. PMID:7800042

  4. Arabidopsis bZIP16 Transcription Factor Integrates Light and Hormone Signaling Pathways to Regulate Early Seedling Development[C][W][OA

    PubMed Central

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

    2012-01-01

    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

  5. Gene Expression Profiling of Pulmonary Fibrosis Identifies Twist1 as an Antiapoptotic Molecular Rectifier of Growth Factor Signaling

    PubMed Central

    Bridges, Robert S.; Kass, Daniel; Loh, Katrina; Glackin, Carlota; Borczuk, Alain C.; Greenberg, Steven

    2009-01-01

    Idiopathic pulmonary fibrosis (IPF) is a progressive and typically fatal lung disease. To gain insight into IPF pathogenesis, we performed gene expression profiling of IPF lungs. Twist1, a basic helix-loop-helix protein, was found among the most consistently and highly up-regulated genes and was expressed in nuclei of type II epithelial cells, macrophages, and fibroblasts in IPF lungs. We studied the function of Twist1 in fibroblasts further, because they are the major effector cells in this disease and persist despite an ambient proapoptotic environment. Twist1 was induced by the profibrotic growth factors (GFs) basic fibroblast growth factor, platelet-derived growth factor, and epidermal growth factor in primary rat lung fibroblasts (RLFs). Suppression of Twist1 expression resulted in decreased RLF accumulation due to increased apoptosis, whereas Twist1 overexpression protected RLFs against several apoptotic stimuli. Addition of platelet-derived growth factor in combination with other GFs led to an increase in proliferation. When Twist1 was depleted, GFs continued to act as mitogens but caused a marked increase in cell death. The increase in apoptosis under basal or growth factor-stimulated conditions was partly mediated by up-regulation of the proapoptotic Bcl-2 family members, Bim and PUMA. These findings indicate that Twist1 promotes survival and accumulation of fibroblasts by shaping their responsiveness to growth factor stimulation. We propose that Twist1 represents one of the factors that promotes pathogenic accumulation of fibroblasts in fibrotic lung disease. PMID:19893041

  6. Basic lubrication equations

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Dowson, D.

    1981-01-01

    Lubricants, usually Newtonian fluids, are assumed to experience laminar flow. The basic equations used to describe the flow are the Navier-Stokes equation of motion. The study of hydrodynamic lubrication is, from a mathematical standpoint, the application of a reduced form of these Navier-Stokes equations in association with the continuity equation. The Reynolds equation can also be derived from first principles, provided of course that the same basic assumptions are adopted in each case. Both methods are used in deriving the Reynolds equation, and the assumptions inherent in reducing the Navier-Stokes equations are specified. Because the Reynolds equation contains viscosity and density terms and these properties depend on temperature and pressure, it is often necessary to couple the Reynolds with energy equation. The lubricant properties and the energy equation are presented. Film thickness, a parameter of the Reynolds equation, is a function of the elastic behavior of the bearing surface. The governing elasticity equation is therefore presented.

  7. Basic Emotions: A Reconstruction

    PubMed Central

    Mason, William A.; Capitanio, John P.

    2016-01-01

    Emotionality is a basic feature of behavior. The argument over whether the expression of emotions is based primarily on culture (constructivism, nurture) or biology (natural forms, nature) will never be resolved because both alternatives are untenable. The evidence is overwhelming that at all ages and all levels of organization, the development of emotionality is epigenetic: The organism is an active participant in its own development. To ascribe these effects to “experience” was the best that could be done for many years. With the rapid acceleration of information on how changes in organization are actually brought about, it is a good time to review, update, and revitalize our views of experience in relation to the concept of basic emotion.

  8. The basics of echocardiography

    PubMed Central

    Mohamed, Alaa A.; Arifi, Ahmed A.; Omran, Ahmed

    2010-01-01

    Cardiac echocardiography is becoming an essential diagnostic tool for a variety of cardiac pathology. Acquiring the necessary knowledge will help non cardiac and the cardiac specialist to understand the echocardiography images and reports and in return will improve the care of the patients. The aim of these of publication is to address the basic knowledge of cardiac echocardiography and the recent advances of its applications. PMID:23960599

  9. Risk communication basics

    SciTech Connect

    Corrado, P.G.

    1995-12-31

    In low-trust, high-concern situations, 50% of your credibility comes from perceived empathy and caring, demonstrated in the first 30 s you come in contact with someone. There is no second chance for a first impression. These and other principles contained in this paper provide you with a basic level of understanding of risk communication. The principles identified are time-tested caveats and will assist you in effectively communicating technical information.

  10. Basics of Biosafety

    NASA Technical Reports Server (NTRS)

    Wong, Willy

    2009-01-01

    This slide presentation reviews the basics of biosafety and the importance of assuring proper biosafety practices. The objectives of the presentation are to review regulations about biosafety, and the different biosafety levels; the biosafety facilities at Johnson Space Center; the usage and maintenance of the biosafety cabinet, the proper methods to handle biologically hazardous materials upon exposure, and the methods of cleanup in the event of a spill, and the training requirements that are mandated for personnel handling biologically hazardous materials.

  11. Basic Hitchhiker Payload Requirements

    NASA Technical Reports Server (NTRS)

    Horan, Stephen

    1999-01-01

    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.

  12. Basic facts about Venus

    NASA Technical Reports Server (NTRS)

    Colin, L.

    1983-01-01

    Because of the disturbing influence of the earth's atmosphere on terrestrial and airborne telescopy, radiometry, thermal mapping, spectroscopy, polarimetry and radar astronomy of Venus, major improvements in the body of theory concerning that planet, began with the Mariner 2 planetary exploration program in 1962. The effect of spacecraft exploration culminated with the influx of data yielded by the Pioneer Venus and Venera 11 and 12 missions of 1978. Attention is presently given to the quantitative enhancement of widely accepted, basic facts about Venus that has resulted from the analysis of space probe data, together with an overview of the major features of past and planned planetary missions.

  13. Menstrual Cycle: Basic Biology

    PubMed Central

    Hawkins, Shannon M.; Matzuk, Martin M.

    2010-01-01

    The basic biology of the menstrual cycle is a complex, coordinated sequence of events involving the hypothalamus, anterior pituitary, ovary, and endometrium. The menstrual cycle with all its complexities can be easily perturbed by environmental factors such as stress, extreme exercise, eating disorders, and obesity. Furthermore, genetic influences such as fragile X premutations (Chapter X), X chromosome abnormalities (Chapter X), and galactose-1-phosphate uridyltransferase (GALT) point mutations (galactosemia) also contribute to perturbations of the menstrual cycle. Although not perfect, mouse model have helped to identify and confirm additional components and pathways in menstrual cycle function and dysfunction in humans. PMID:18574203

  14. Basic and clinical immunology

    NASA Technical Reports Server (NTRS)

    Chinen, Javier; Shearer, William T.

    2003-01-01

    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.

  15. An atypical bHLH transcription factor regulates early xylem development downstream of auxin.

    PubMed

    Ohashi-Ito, Kyoko; Matsukawa, Manami; Fukuda, Hiroo

    2013-03-01

    The vascular system in plants, which comprises xylem, phloem and vascular stem cells, originates from provascular cells and forms a continuous network throughout the plant body. Although various aspects of vascular development have been extensively studied, the early process of vascular development remains largely unknown. LONESOME HIGHWAY (LHW), which encodes an atypical basic helix-loop-helix (bHLH) transcription factor, plays an essential role in establishing vascular cells. Here, we report the analysis of LHW homologs in relation to vascular development. Three LHW homologs, LONESOME HIGHWAY LIKE 1-3 (LHL1-LHL3), were preferentially expressed in the plant vasculature. Genetic analysis indicated that, although the LHL3 loss-of-function mutant showed no obvious phenotype, the lhw lhl3 double mutant displayed more severe phenotypic defects in the vasculature of the cotyledons and roots than the lhw single mutant. Only one xylem vessel was formed at the metaxylem position in lhw lhl3 roots, whereas the lhw root formed one protoxylem and one or two metaxylem vessels. Conversely, overexpression of LHL3 enhanced xylem development in the roots. Moreover, N-1-naphthylphthalamic acid caused ectopic LHL3 expression in accordance with induced auxin maximum. These results suggest that LHL3 plays a positive role in xylem differentiation downstream of auxin. PMID:23359424

  16. Sim1 inhibits bone formation by enhancing the sympathetic tone in male mice.

    PubMed

    Wang, Xunde; Wei, Wei; Zinn, Andrew R; Wan, Yihong

    2015-04-01

    Single-minded 1 (Sim1) is a basic helix-loop-helix Per-Arnt-Sim transcription factor that is important for neuronal development in the hypothalamus. Loss-of-function mutation of Sim1 causes early-onset obesity. However, it is unknown whether and how Sim1 regulates bone remodeling. In this study, we found that adult-onset Sim1 deletion increases bone formation, leading to high bone mass. In contrast, Sim1-overexpressing transgenic mice exhibit decreased bone formation and low bone mass. Sim1 does not directly regulate osteoblastogenesis, because bone marrow mesenchymal stem cells from Sim1 mutant mice display a normal capacity for osteoblast differentiation. Instead, Sim1 inhibits bone formation via stimulating the sympathetic nervous system, because sympathetic tone is decreased by Sim1 deletion but increased by Sim1 overexpression. Treatment with the β-adrenergic agonist isoproterenol effectively reverses the high bone mass in Sim1-knockout mice. These findings reveal Sim1 as a critical yet previously unrecognized modulator of skeletal homeostasis that functions through a central relay. PMID:25607894

  17. Mesogenin 1 is a master regulator of paraxial presomitic mesoderm differentiation.

    PubMed

    Chalamalasetty, Ravindra B; Garriock, Robert J; Dunty, William C; Kennedy, Mark W; Jailwala, Parthav; Si, Han; Yamaguchi, Terry P

    2014-11-01

    Neuromesodermal (NM) stem cells generate neural and paraxial presomitic mesoderm (PSM) cells, which are the respective progenitors of the spinal cord and musculoskeleton of the trunk and tail. The Wnt-regulated basic helix-loop-helix (bHLH) transcription factor mesogenin 1 (Msgn1) has been implicated as a cooperative regulator working in concert with T-box genes to control PSM formation in zebrafish, although the mechanism is unknown. We show here that, in mice, Msgn1 alone controls PSM differentiation by directly activating the transcriptional programs that define PSM identity, epithelial-mesenchymal transition, motility and segmentation. Forced expression of Msgn1 in NM stem cells in vivo reduced the contribution of their progeny to the neural tube, and dramatically expanded the unsegmented mesenchymal PSM while blocking somitogenesis and notochord differentiation. Expression of Msgn1 was sufficient to partially rescue PSM differentiation in Wnt3a(-/-) embryos, demonstrating that Msgn1 functions downstream of Wnt3a as the master regulator of PSM differentiation. Our data provide new insights into how cell fate decisions are imposed by the expression of a single transcriptional regulator. PMID:25371364

  18. Genetic Factors for Enhancement of Nicotine Levels in Cultivated Tobacco

    PubMed Central

    Wang, Bingwu; Lewis, Ramsey S.; Shi, Junli; Song, Zhongbang; Gao, Yulong; Li, Wenzheng; Chen, Hongxia; Qu, Rongda

    2015-01-01

    Nicotine has practical applications relating to smoking cessation devices and alternative nicotine products. Genetic manipulation for increasing nicotine content in cultivated tobacco (Nicotiana tabacum L.) may be of value for industrial purposes, including the possibility of enhancing the efficiency of nicotine extraction. Biotechnological approaches have been evaluated in connection with this objective, but field-based results are few. Here, we report characterization of two genes encoding basic-helix-loop-helix (bHLH) transcription factors (TFs), NtMYC2a and NtMYC2b from tobacco. Overexpression of NtMYC2a increased leaf nicotine levels in T1 transgenic lines approximately 2.3-fold in greenhouse-grown plants of tobacco cultivar ‘NC 95′. Subsequent field testing of T2 and T3 generations of transgenic NtMYC2a overexpression lines showed nicotine concentrations were 76% and 58% higher than control lines, respectively. These results demonstrated that the increased nicotine trait was stably inherited to the T2 and T3 generations, indicating the important role that NtMYC2a plays in regulating nicotine accumulation in N. tabacum and the great potential of NtMYC2a overexpression in tobacco plants for industrial nicotine production. Collected data in this study also indicated a negative feedback inhibition of nicotine biosynthesis. Further enhancement of nicotine accumulation in tobacco leaf may require modification of the processes of nicotine transport and deposition. PMID:26626731

  19. 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

    Sorensen, Karina Dalsgaard; Kunder, Sandra; Quintanilla-Martinez, Leticia; Sorensen, Jonna; Schmidt, Joerg; Pedersen, Finn Skou . E-mail: fsp@mb.au.dk

    2007-05-25

    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.

  20. Homeodomain-Leucine zipper II family of transcription factors to the limelight

    PubMed Central

    Carabelli, Monica; Turchi, Luana; Ruzza, Valentino; Morelli, Giorgio; Ruberti, Ida

    2013-01-01

    The Arabidopsis genome encodes 10 Homeodomain-Leucine Zipper (HD-Zip) II transcription factors that can be subdivided into 4 clades (α–δ). All the γ (ARABIDOPSIS THALIANA HOMEOBOX 2 [ATHB2], HOMEOBOX ARABIDOPSIS THALIANA 1 [HAT1], HAT2) and δ (HAT3, ATHB4) genes are regulated by light quality changes (Low Red [R]/Far-Red [FR]) that induce the shade avoidance response in most of the angiosperms. HD-Zip IIγ and HD-Zip IIδ transcription factors function as positive regulators of shade avoidance, and there is evidence that at least ATHB2 is directly positively regulated by the basic Helix-Loop-Helix (bHLH) proteins PHYTOCHROME INTERACTING FACTOR 4 (PIF4) and PIF5. Recent evidence demonstrate that, in addition to their function in shade avoidance, HD-Zip IIγ and HD-Zip IIδ proteins play an essential role in plant development from embryogenesis onwards in a white light environment. PMID:23838958

  1. The members of bHLH transcription factor superfamily are required for female reproduction in the red flour beetle, Tribolium castaneum

    PubMed Central

    Bitra, Kavita; Palli, Subba R.

    2010-01-01

    Proteins containing the basic Helix-Loop-Helix (bHLH) domain function as transcription factors and play important roles during the development of various metazoans including insects, nematodes and vertebrates. Insect genomes contain more than 50 bHLH transcription factors, but the function of only a few of these proteins in regulation of female reproduction is known. Using RNA interference, we have tested knock-down in the expression of genes coding for bHLH transcription factors in newly emerged adult females to determine their function in regulation of female reproduction in the red flour beetle, Tribolium castaneum. Knock-down in the expression of genes coding for four bHLH transcription factors (TcSRC, TcSim1, TcAsh and TcDaughterless) has caused mortality in the female beetles. In addition, knocking-down the expression of 16 bHLH genes has affected oogenesis and knock-down in the expression of 13 genes has affected embryogenesis. Two genes TcSide1 and TcSpineless are required for both oogenesis and embryogenesis. Thus, the data reported here showed that 31 bHLH transcription factors are required for female survival, reproduction and embryogenesis. PMID:20223247

  2. Structure-based Inhibitor Design for the Intrinsically Disordered Protein c-Myc.

    PubMed

    Yu, Chen; Niu, Xiaogang; Jin, Fan; Liu, Zhirong; Jin, Changwen; Lai, Luhua

    2016-01-01

    Intrinsically disordered proteins (IDPs) are associated with various diseases and have been proposed as promising drug targets. However, conventional structure-based approaches cannot be applied directly to IDPs, due to their lack of ordered structures. Here, we describe a novel computational approach to virtually screen for compounds that can simultaneously bind to different IDP conformations. The test system used c-Myc, an oncoprotein containing a disordered basic helix-loop-helix-leucine zipper (bHLH-LZ) domain that adopts a helical conformation upon binding to Myc-associated factor X (Max). For the virtual screen, we used three binding pockets in representative conformations of c-Myc370-409, which is part of the disordered bHLH-LZ domain. Seven compounds were found to directly bind c-Myc370-409 in vitro, and four inhibited the growth of the c-Myc-overexpressing cells by affecting cell cycle progression. Our approach of IDP conformation sampling, binding site identification, and virtual screening for compounds that can bind to multiple conformations provides a useful strategy for structure-based drug discovery targeting IDPs. PMID:26931396

  3. Ovarian gene expression in the absence of FIGLA, an oocyte-specific transcription factor

    PubMed Central

    Joshi, Saurabh; Davies, Holly; Sims, Lauren Porter; Levy, Shawn E; Dean, Jurrien

    2007-01-01

    Background Ovarian folliculogenesis in mammals is a complex process involving interactions between germ and somatic cells. Carefully orchestrated expression of transcription factors, cell adhesion molecules and growth factors are required for success. We have identified a germ-cell specific, basic helix-loop-helix transcription factor, FIGLA (Factor In the GermLine, Alpha) and demonstrated its involvement in two independent developmental processes: formation of the primordial follicle and coordinate expression of zona pellucida genes. Results Taking advantage of Figla null mouse lines, we have used a combined approach of microarray and Serial Analysis of Gene Expression (SAGE) to identify potential downstream target genes. Using high stringent cutoffs, we find that FIGLA functions as a key regulatory molecule in coordinating expression of the NALP family of genes, genes of known oocyte-specific expression and a set of functionally un-annotated genes. FIGLA also inhibits expression of male germ cell specific genes that might otherwise disrupt normal oogenesis. Conclusion These data implicate FIGLA as a central regulator of oocyte-specific genes that play roles in folliculogenesis, fertilization and early development. PMID:17567914

  4. Setleis syndrome due to inheritance of the 1p36.22p36.21 duplication: evidence for lack of penetrance.

    PubMed

    Lee, Beom Hee; Kasparis, Christos; Chen, Brenden; Mei, Hui; Edelmann, Lisa; Moss, Celia; Weaver, David D; Desnick, Robert J

    2015-11-01

    Setleis syndrome, focal facial dermal dysplasia type III (FFDD3, MIM #227260), is characterized by scar-like bitemporal lesions and other ocular and facial dysmorphic features. The syndrome results from recessive mutations in the TWIST2 gene, encoding a basic helix-loop-helix transcription factor or de novo genomic duplication or triplication, which include 1.3 Mb at 1p36.22p36.21, or other yet undefined lesions, emphasizing the syndrome's genetic heterogeneity. Recently, three patients were reported with 1p36.22p36.21 duplications/triplication that had the characteristic FFDD3 features and developmental delay or intellectual disabilities. Here, we describe a male with this microduplication, and the typical FFDD3 phenotype, but normal intelligence. Notably, his duplication was inherited from his father who did not have any FFDD3 manifestations, indicating lack of penetrance of the 1p36.22p36.21 microduplication. These findings emphasize phenotypic heterogeneity of the 1p36.22p36.21 copy number variant and the importance of screening the parents of patients with the 1p36.22p36.21 copy number variant to determine whether the duplication/triplication is de novo or inherited, for informed reproductive and genetic counseling. PMID:26311541

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

    PubMed Central

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

    2010-01-01

    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

  6. Embryonic expression of zebrafish MiT family genes tfe3b, tfeb, and tfec

    PubMed Central

    Lister, James A.; Lane, Brandon M.; Nguyen, AnhThu; Lunney, Katherine

    2011-01-01

    The MiT family comprises four genes in mammals: Mitf, Tfe3, Tfeb, and Tfec, which encode transcription factors of the basic-helix-loop-helix/leucine zipper class. Mitf is well-known for its essential role in the development of melanocytes, however the functions of the other members of this family, and of interactions between them, are less well understood. We have now characterized the complete set of MiT genes from zebrafish, which totals six instead of four. The zebrafish genome contain two mitf (mitfa and mitfb), two tfe3 (tfe3a and tfe3b), and single tfeb and tfec genes; this distribution is shared with other teleosts. We present here the sequence and embryonic expression patterns for the zebrafish tfe3b, tfeb and tfec genes, and identify a new isoform of tfe3a. These findings will assist in elucidating the roles of the MiT gene family over the course of vertebrate evolution. PMID:21932325

  7. High-temperature inhibition of biosynthesis and transportation of anthocyanins results in the poor red coloration in red-fleshed Actinidia chinensis.

    PubMed

    Man, Yu-Ping; Wang, Yan-Chang; Li, Zuo-Zhou; Jiang, Zheng-Wang; Yang, Hong-Li; Gong, Jun-Jie; He, Shi-Song; Wu, Shi-Quan; Yang, Zuo-Quan; Zheng, Jing; Wang, Zhong-Yan

    2015-04-01

    In plants, the role of anthocyanins trafficking in response to high temperature has been rarely studied, and therefore poorly understood. Red-fleshed kiwifruit has stimulated the world kiwifruit industry owing to its appealing color. However, fruit in warmer climates have been found to have poor flesh coloration, and the factors responsible for this response remain elusive. Partial correlation and regression analysis confirmed that accumulative temperatures above 25 °C (T25) was one of the dominant factors inhibiting anthocyanin accumulation in red-fleshed Actinidia chinensis, 'Hongyang'. Expression of structural genes, AcMRP and AcMYB1 in inner pericarp sampled from the two high altitudes (low temperature area), was notably higher than the low altitude (high temperature area) during fruit coloration. AcMYB1 and structural genes coordinate expression supported the MYB-bHLH (basic helix-loop-helix)-WD40 regulatory complex mediated downregulation of anthocyanin biosynthesis induced by high temperatures in kiwifruit. Moreover, cytological observations using the light and transmission electronic microscopy showed that there were a series of anthocyanic vacuolar inclusion (AVI)-like structures involved in their vacuolization process and dissolution of the pigmented bodies inside cells of fruit inner pericarp. Anthocyanin transport was inhibited by high temperature via retardation of vacuolization or reduction in AIV-like structure formation. Our findings strongly suggested that complex multimechanisms influenced the effects of high temperature on red-fleshed kiwifruit coloration. PMID:25143057

  8. Disruption of Neurogenesis and Cortical Development in Transgenic Mice Misexpressing Olig2, A Gene In The Down Syndrome Critical Region

    PubMed Central

    Liu, Wei; Zhou, Hui; Liu, Lei; Zhao, Chuntao; Deng, Yaqi; Chen, Lina; Wu, Laiman; Mandrycky, Nicole; McNabb, Christopher T.; Peng, Yuanbo; Fuchs, Perry N; Lu, Jie; Sheen, Volney; Qiu, Mengsheng; Mao, Meng; Lu, Q. Richard

    2015-01-01

    The basic helix-loop-helix (bHLH) transcription factor Olig2 is crucial for mammalian central nervous system development. Human ortholog OLIG2 is located in the Down syndrome critical region in trisomy 21. To investigate the effect of Olig2 misexpression on brain development, we generated a developmentally regulated Olig2-overexpressing transgenic line with a Cre/loxP system. The transgenic mice with Olig2 misexpression in cortical neural stem/progenitor cells exhibited microcephaly, cortical dyslamination, hippocampus malformation, and profound motor deficits. Ectopic misexpression of Olig2 impaired cortical progenitor proliferation and caused precocious cell cycle exit. Massive neuronal cell death was detected in the developing cortex of Olig2-misexpressing mice. In addition, Olig2 misexpression led to a significant downregulation of neuronal specification factors including Ngn1, Ngn2 and Pax6, and a defect in cortical neurogenesis. Chromatin-immunoprecipitation and sequencing (ChIP-Seq) analysis indicates that Olig2 directly targets the promoter and/or enhancer regions of Nfatc4, Dscr1/Rcan1 and Dyrk1a, the critical neurogenic genes that contribute to Down syndrome phenotypes, and inhibits their expression. Together, our study suggests that Olig2 misexpression in neural stem cells elicits neurogenesis defects and neuronal cell death, which may contribute to developmental disorders including Down syndrome, where OLIG2 is triplicated on chromosomal 21. PMID:25747816

  9. Heme-based sensors: defining characteristics, recent developments, and regulatory hypotheses.

    PubMed

    Gilles-Gonzalez, Marie-Alda; Gonzalez, Gonzalo

    2005-01-01

    In a great variety of organisms throughout all kingdoms of life, the heme-based-sensor proteins are the key regulators of adaptive responses to fluctuating oxygen, carbon monoxide, and nitric oxide levels. These signal transducers achieve their responses by coupling a regulatory heme-binding domain to a neighboring transmitter. The past decade has witnessed an explosion in the numbers of these modular sensory proteins known, from just two recognized members, FixL and soluble guanylyl cyclase (sGC), to four broad families comprising more than 50 sensors. Heme-based sensors so far feature four different types of heme-binding modules: the heme-binding PAS domain, globin-coupled sensor (GCS), CooA, and heme-NO-binding (HNOB). The transmitters for coupling to such heme-binding domains include histidine protein kinases, cyclic nucleotide phosphodiesterases, chemotaxis methyl-carrier protein receptors, and transcription factors of the basic helix-loop-helix and helix-turn-helix classes. Some well-studied sensors are the FixL, EcDos, AxPDEA1, NPAS2, HemAT-Bs, HemAT-Hs, CooA, and sGC proteins. This review elaborates the defining characteristics of heme-based sensors, examines recent developments on those proteins, and discusses the regulatory hypotheses proposed for those sensors. A general, "helix-swap", model is also proposed here for signal transduction by PAS domains. PMID:15598487

  10. Brg1 directly regulates Olig2 transcription and is required for oligodendrocyte progenitor cell specification.

    PubMed

    Matsumoto, Steven; Banine, Fatima; Feistel, Kerstin; Foster, Scott; Xing, Rubing; Struve, Jaime; Sherman, Larry S

    2016-05-15

    The Olig2 basic-helix-loop-helix transcription factor promotes oligodendrocyte specification in early neural progenitor cells (NPCs), including radial glial cells, in part by recruiting SWI/SNF chromatin remodeling complexes to the enhancers of genes involved in oligodendrocyte differentiation. How Olig2 expression is regulated during oligodendrogliogenesis is not clear. Here, we find that the Brg1 subunit of SWI/SNF complexes interacts with a proximal Olig2 promoter and represses Olig2 transcription in the mouse cortex at E14, when oligodendrocyte progenitors (OPCs) are not yet found in this location. Brg1 does not interact with the Olig2 promoter in the E14 ganglionic eminence, where NPCs differentiate into Olig2-positive OPCs. Consistent with these findings, Brg1-null NPCs demonstrate precocious expression of Olig2 in the cortex. However, these cells fail to differentiate into OPCs. We further find that Brg1 is necessary for neuroepithelial-to-radial glial cell transition, but not neuronal differentiation despite a reduction in expression of the pro-neural transcription factor Pax6. Collectively, these and earlier findings support a model whereby Brg1 promotes neurogenic radial glial progenitor cell specification but is dispensable for neuronal differentiation. Concurrently, Brg1 represses Olig2 expression and the specification of OPCs, but is required for OPC differentiation and oligodendrocyte maturation. PMID:27067865

  11. The mutational spectrum in Waardenburg syndrome

    SciTech Connect

    Read, A.P.; Tassabehji, M.; Liu, X.Z.

    1994-09-01

    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.

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

    PubMed

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

    2013-11-01

    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

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

    PubMed Central

    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.

    2013-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    Schwartz, Robert J.

    1997-01-01

    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.

  15. Embryonic expression of zebrafish MiT family genes tfe3b, tfeb, and tfec.

    PubMed

    Lister, James A; Lane, Brandon M; Nguyen, Anhthu; Lunney, Katherine

    2011-11-01

    The MiT family comprises four genes in mammals: Mitf, Tfe3, Tfeb, and Tfec, which encode transcription factors of the basic-helix-loop-helix/leucine zipper class. Mitf is well-known for its essential role in the development of melanocytes, however the functions of the other members of this family, and of interactions between them, are less well understood. We have now characterized the complete set of MiT genes from zebrafish, which totals six instead of four. The zebrafish genome contain two mitf (mitfa and mitfb), two tfe3 (tfe3a and tfe3b), and single tfeb and tfec genes; this distribution is shared with other teleosts. We present here the sequence and embryonic expression patterns for the zebrafish tfe3b, tfeb, and tfec genes, and identify a new isoform of tfe3a. These findings will assist in elucidating the roles of the MiT gene family over the course of vertebrate evolution. PMID:21932325

  16. Arabidopsis MYC Transcription Factors Are the Target of Hormonal Salicylic Acid/Jasmonic Acid Cross Talk in Response to Pieris brassicae Egg Extract.

    PubMed

    Schmiesing, André; Emonet, Aurélia; Gouhier-Darimont, Caroline; Reymond, Philippe

    2016-04-01

    Arabidopsis (Arabidopsis thaliana) plants recognize insect eggs and activate the salicylic acid (SA) pathway. As a consequence, expression of defense genes regulated by the jasmonic acid (JA) pathway is suppressed and larval performance is enhanced. Cross talk between defense signaling pathways is common in plant-pathogen interactions, but the molecular mechanism mediating this phenomenon is poorly understood. Here, we demonstrate that egg-induced SA/JA antagonism works independently of the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor ORA59, which controls the ERF branch of the JA pathway. In addition, treatment with egg extract did not enhance expression or stability of JASMONATE ZIM-domain transcriptional repressors, and SA/JA cross talk did not involve JASMONATE ASSOCIATED MYC2-LIKEs, which are negative regulators of the JA pathway. Investigating the stability of MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that additively control jasmonate-related defense responses, we found that egg extract treatment strongly diminished MYC protein levels in an SA-dependent manner. Furthermore, we identified WRKY75 as a novel and essential factor controlling SA/JA cross talk. These data indicate that insect eggs target the MYC branch of the JA pathway and uncover an unexpected modulation of SA/JA antagonism depending on the biological context in which the SA pathway is activated. PMID:26884488

  17. DEC1 and DEC2 Crosstalk between Circadian Rhythm and Tumor Progression.

    PubMed

    Sato, Fuyuki; Bhawal, Ujjal K; Yoshimura, Tomohiro; Muragaki, Yasuteru

    2016-01-01

    Clock genes, major regulators of circadian rhythm, are involved in tumor progression. We have shown that clock genes basic helix-loop-helix (BHLH) transcription factors, differentiated embryonic chondrocyte gene 1 (DEC1/BHLHE40/Sharp2/Stra13) and DEC2 (BHLHE41/Sharp1) play important roles in circadian rhythm, cell proliferation, apoptosis, hypoxia response, various stresses, and epithelial-to-mesenchymal transition (EMT) of tumor cells. Various stresses, such as exposure to transforming growth factor-beta (TGF-β), hypoxia, cytokines, serum-free, and anti-tumor drugs affect DEC1 and DEC2 expression. An increased or decreased expression of DEC1 and DEC2 regulated tumor progression. However, DEC1 and DEC2 have opposite effects in tumor progression, where the reason behind remains unclear. We found that DEC2 has circadian expression in implanted mouse sarcoma cells, suggesting that DEC2 regulates tumor progression under circadian rhythm. In addition to that, we showed that DEC1 and DEC2 regulate target genes via positive or negative feedback system in tumor progression. We propose that DEC1 and DEC2 act as an accelerator or a brake in tumor progression. In this review, we summarize current progress of knowledge in the function of DEC1 and DEC2 genes in tumor progression. PMID:26819638

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

    SciTech Connect

    Zanocco-Marani, Tommaso; Vignudelli, Tatiana; Gemelli, Claudia; Pirondi, Sara; Testa, Anna; Montanari, Monica; Parenti, Sandra; Tenedini, Elena; Grande, Alexis; Ferrari, Sergio . E-mail: sergio@unimo.it

    2006-12-10

    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.

  19. Hypoxia Inhibits Myogenic Differentiation through p53 Protein-dependent Induction of Bhlhe40 Protein.

    PubMed

    Wang, Chao; Liu, Weiyi; Liu, Zuojun; Chen, Long; Liu, Xiaoqi; Kuang, Shihuan

    2015-12-11

    Satellite cells are muscle-resident stem cells capable of self-renewal and differentiation to repair injured muscles. However, muscle injury often leads to an ischemic hypoxia environment that impedes satellite cell differentiation and reduces the efficiency of muscle regeneration. Here we performed microarray analyses and identified the basic helix-loop-helix family transcription factor Bhlhe40 as a candidate mediator of the myogenic inhibitory effect of hypoxia. Bhlhe40 is strongly induced by hypoxia in satellite cell-derived primary myoblasts. Overexpression of Bhlhe40 inhibits Myog expression and mimics the effect of hypoxia on myogenesis. Inhibition of Bhlhe40, conversely, up-regulates Myog expression and promotes myogenic differentiation. Importantly, Bhlhe40 knockdown rescues myogenic differentiation under hypoxia. Mechanistically, Bhlhe40 binds to the proximal E-boxes of the Myog promoter and reduces the binding affinity and transcriptional activity of MyoD on Myog. Interestingly, hypoxia induces Bhlhe40 expression independent of HIF1α but through a novel p53-dependent signaling pathway. Our study establishes a crucial role of Bhlhe40 in mediating the repressive effect of hypoxia on myogenic differentiation and suggests that inhibition of Bhlhe40 or p53 may facilitate muscle regeneration after ischemic injuries. PMID:26468276

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

    PubMed

    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

    2014-04-01

    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/β-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

  1. Roles of bHLH genes in neural stem cell differentiation

    SciTech Connect

    Kageyama, Ryoichiro . E-mail: rkageyam@virus.kyoto-u.ac.jp; Ohtsuka, Toshiyuki; Hatakeyama, Jun; Ohsawa, Ryosuke

    2005-06-10

    Neural stem cells change their characteristics over time during development: they initially proliferate only and then give rise to neurons first and glial cells later. In the absence of the repressor-type basic helix-loop-helix (bHLH) genes Hes1, Hes3 and Hes5, neural stem cells do not proliferate sufficiently but prematurely differentiate into neurons and become depleted without making the later born cell types such as astrocytes and ependymal cells. Thus, Hes genes are essential for maintenance of neural stem cells to make cells not only in correct numbers but also in full diversity. Hes genes antagonize the activator-type bHLH genes, which include Mash1, Math and Neurogenin. The activator-type bHLH genes promote the neuronal fate determination and induce expression of Notch ligands such as Delta. These ligands activate Notch signaling and upregulate Hes1 and Hes5 expression in neighboring cells, thereby maintaining these cells undifferentiated. Thus, the activator-type and repressor-type bHLH genes regulate each other, allowing only subsets of cells to undergo differentiation while keeping others to stay neural stem cells. This regulation is essential for generation of complex brain structures of appropriate size, shape and cell arrangement.

  2. Site-directed mutagenesis and saturation mutagenesis for the functional study of transcription factors involved in plant secondary metabolite biosynthesis.

    PubMed

    Pattanaik, Sitakanta; Werkman, Joshua R; Kong, Que; Yuan, Ling

    2010-01-01

    Regulation of gene expression is largely coordinated by a complex network of interactions between transcription factors (TFs), co-factors, and their cognate cis-regulatory elements in the genome. TFs are multidomain proteins that arise evolutionarily through protein domain shuffling. The modular nature of TFs has led to the idea that specific modules of TFs can be re-designed to regulate desired gene(s) through protein engineering. Utilization of designer TFs for the control of metabolic pathways has emerged as an effective approach for metabolic engineering. We are interested in engineering the basic helix-loop-helix (bHLH, Myc-type) transcription factors. Using site-directed and saturation mutagenesis, in combination with efficient and high-throughput screening systems, we have identified and characterized several amino acid residues critical for higher transactivation activity of a Myc-like bHLH transcription factor involved in anthocyanin biosynthetic pathway in plants. Site-directed and saturation mutagenesis should be generally applicable to engineering of all TFs. PMID:20552443

  3. Molecular cloning, polyclonal antibody preparation, and characterization of a functional iron-related transcription factor IRO2 from Malus xiaojinensis.

    PubMed

    Yin, Lili; Wang, Yi; Yan, Mudan; Zhang, Xinzhong; Pan, Haifa; Xu, Xuefeng; Han, Zhenhai

    2013-06-01

    Transcription factors play important roles in plant growth and responses to environmental stresses. In this study, a novel basic helix-loop-helix iron-related transcription factor, IRO2, containing a 762-bp open reading frame and encoding 253 amino acids, was cloned from the iron-efficient genotype of Malus xiaojinensis. Localization analyses in onion showed that the MxIRO2 protein was targeted to the nucleus and activation studies in yeast indicated MxIRO2-BD had weak transcriptional activation activity. Prokaryotic expression of MxIRO2 in Escherichia coli BL21 (DE3) pLysS cells resulted in high expression levels of the protein when induced with isopropyl-β-d-thiogalactoside. The fusion protein was purified using Ni-NTA His-bind resin, and the purified MxIRO2-His fusion protein was used as the antigen to immunize a New Zealand rabbit. The resulting antiserum was purified by precipitation with 50% saturated ammonium sulfate and DEAE Sephadex A-50 chromatography to obtain the immunoglobulin G fraction. The expression of MxIRO2 in roots and leaves of M. xiaojinensis seedlings under iron deficiency was determined. The results indicated that MxIRO2 was induced in both roots and leaves under iron deficiency. In these experimental conditions, the transcription and translation levels first increased and then decreased under iron deficiency. This work offers an important basis for further investigating the mechanisms of fruit tree adaptation to iron deficiency. PMID:23542185

  4. C. elegans SoxB genes are dispensable for embryonic neurogenesis but required for terminal differentiation of specific neuron types

    PubMed Central

    Vidal, Berta; Santella, Anthony; Serrano-Saiz, Esther; Bao, Zhirong; Chuang, Chiou-Fen; Hobert, Oliver

    2015-01-01

    Neurogenesis involves deeply conserved patterning molecules, such as the proneural basic helix-loop-helix transcription factors. Sox proteins and specifically members of the SoxB and SoxC groups are another class of conserved transcription factors with an important role in neuronal fate commitment and differentiation in various species. In this study, we examine the expression of all five Sox genes of the nematode C. elegans and analyze the effect of null mutant alleles of all members of the SoxB and SoxC groups on nervous system development. Surprisingly, we find that, unlike in other systems, neither of the two C. elegans SoxB genes sox-2 (SoxB1) and sox-3 (SoxB2), nor the sole C. elegans SoxC gene sem-2, is broadly expressed throughout the embryonic or adult nervous system and that all three genes are mostly dispensable for embryonic neurogenesis. Instead, sox-2 is required to maintain the developmental potential of blast cells that are generated in the embryo but divide only postembryonically to give rise to differentiated neuronal cell types. Moreover, sox-2 and sox-3 have selective roles in the terminal differentiation of specific neuronal cell types. Our findings suggest that the common themes of SoxB gene function across phylogeny lie in specifying developmental potential and, later on, in selectively controlling terminal differentiation programs of specific neuron types, but not in broadly controlling neurogenesis. PMID:26153233

  5. The Transcriptional Repressor MYB2 Regulates Both Spatial and Temporal Patterns of Proanthocyandin and Anthocyanin Pigmentation in Medicago truncatula.

    PubMed

    Jun, Ji Hyung; Liu, Chenggang; Xiao, Xirong; Dixon, Richard A

    2015-10-01

    Accumulation of anthocyanins and proanthocyanidins (PAs) is limited to specific cell types and developmental stages, but little is known about how antagonistically acting transcriptional regulators work together to determine temporal and spatial patterning of pigmentation at the cellular level, especially for PAs. Here, we characterize MYB2, a transcriptional repressor regulating both anthocyanin and PA biosynthesis in the model legume Medicago truncatula. MYB2 was strongly upregulated by MYB5, a major regulator of PA biosynthesis in M. truncatula and a component of MYB-basic helix loop helix-WD40 (MBW) activator complexes. Overexpression of MYB2 abolished anthocyanin and PA accumulation in M. truncatula hairy roots and Arabidopsis thaliana seeds, respectively. Anthocyanin deposition was expanded in myb2 mutant seedlings and flowers accompanied by increased anthocyanin content. PA mainly accumulated in the epidermal layer derived from the outer integument in the M. truncatula seed coat, starting from the hilum area. The area of PA accumulation and ANTHOCYANIDIN REDUCTASE expression was expanded into the seed body at the early stage of seed development in the myb2 mutant. Genetic, biochemical, and cell biological evidence suggests that MYB2 functions as part of a multidimensional regulatory network to define the temporal and spatial pattern of anthocyanin and PA accumulation linked to developmental processes. PMID:26410301

  6. 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

    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

    2013-01-01

    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

  7. Control of lysosomal biogenesis and Notch-dependent tissue patterning by components of the TFEB-V-ATPase axis in Drosophila melanogaster

    PubMed Central

    Tognon, Emiliana; Kobia, Francis; Busi, Ilaria; Fumagalli, Arianna; De Masi, Federico; Vaccari, Thomas

    2016-01-01

    ABSTRACT In vertebrates, TFEB (transcription factor EB) and MITF (microphthalmia-associated transcription factor) family of basic Helix-Loop-Helix (bHLH) transcription factors regulates both lysosomal function and organ development. However, it is not clear whether these 2 processes are interconnected. Here, we show that Mitf, the single TFEB and MITF ortholog in Drosophila, controls expression of vacuolar-type H+-ATPase pump (V-ATPase) subunits. Remarkably, we also find that expression of Vha16-1 and Vha13, encoding 2 key components of V-ATPase, is patterned in the wing imaginal disc. In particular, Vha16-1 expression follows differentiation of proneural regions of the disc. These regions, which will form sensory organs in the adult, appear to possess a distinctive endolysosomal compartment and Notch (N) localization. Modulation of Mitf activity in the disc in vivo alters endolysosomal function and disrupts proneural patterning. Similar to our findings in Drosophila, in human breast epithelial cells we observe that impairment of the Vha16-1 human ortholog ATP6V0C changes the size and function of the endolysosomal compartment and that depletion of TFEB reduces ligand-independent N signaling activity. Our data suggest that lysosomal-associated functions regulated by the TFEB-V-ATPase axis might play a conserved role in shaping cell fate. PMID:26727288

  8. Twist1 promotes heart valve cell proliferation and extracellular matrix gene expression during development in vivo and is expressed in human diseased aortic valves

    PubMed Central

    Chakraborty, Santanu; Wirrig, Elaine E.; Hinton, Robert B.; Merrill, Walter H.; Spicer, Douglas B.; Yutzey, Katherine E.

    2010-01-01

    During embryogenesis the heart valves develop from undifferentiated mesenchymal endocardial cushions (EC), and activated interstitial cells of adult diseased valves share characteristics of embryonic valve progenitors. Twist1, a class II basic-helix-loop-helix (bHLH) transcription factor, is expressed during early EC development and is downregulated later during valve remodeling. The requirements for Twist1 down-regulation in the remodeling valves and the consequences of prolonged Twist1 activity were examined in transgenic mice with persistent expression of Twist1 in developing and mature valves. Persistent Twist1 expression in the remodeling valves leads to increased valve cell proliferation, increased expression of Tbx20, and increased extracellular matrix (ECM) gene expression, characteristic of early valve progenitors. Among the ECM genes predominant in the EC, Col2a1 was identified as a direct transcriptional target of Twist1. Increased Twist1 expression also leads to dysregulation of fibrillar collagen and periostin expression, as well as enlarged hypercellular valve leaflets prior to birth. In human diseased aortic valves, increased Twist1 expression and cell proliferation are observed adjacent to nodules of calcification. Overall, these data implicate Twist1 as a critical regulator of valve development and suggest that Twist1 influences ECM production and cell proliferation during disease. PMID:20804746

  9. Overexpression of EcbHLH57 Transcription Factor from Eleusine coracana L. in Tobacco Confers Tolerance to Salt, Oxidative and Drought Stress

    PubMed Central

    Nataraja, Karaba N.; Udayakumar, M.

    2015-01-01

    Basic helix-loop-helix (bHLH) transcription factors constitute one of the largest families in plants and are known to be involved in various developmental processes and stress tolerance. We report the characterization of a stress responsive bHLH transcription factor from stress adapted species finger millet which is homologous to OsbHLH57 and designated as EcbHLH57. The full length sequence of EcbHLH57 consisted of 256 amino acids with a conserved bHLH domain followed by leucine repeats. In finger millet, EcbHLH57 transcripts were induced by ABA, NaCl, PEG, methyl viologen (MV) treatments and drought stress. Overexpression of EcbHLH57 in tobacco significantly increased the tolerance to salinity and drought stress with improved root growth. Transgenic plants showed higher photosynthetic rate and stomatal conductance under drought stress that resulted in higher biomass. Under long-term salinity stress, the transgenic plants accumulated higher seed weight/pod and pod number. The transgenic plants were also tolerant to oxidative stress and showed less accumulation of H202 and MDA levels. The overexpression of EcbHLH57 enhanced the expression of stress responsive genes such as LEA14, rd29A, rd29B, SOD, APX, ADH1, HSP70 and also PP2C and hence improved tolerance to diverse stresses. PMID:26366726

  10. Genome-wide characterisation and analysis of bHLH transcription factors related to tanshinone biosynthesis in Salvia miltiorrhiza

    PubMed Central

    Zhang, Xin; Luo, Hongmei; Xu, Zhichao; Zhu, Yingjie; Ji, Aijia; Song, Jingyuan; Chen, Shilin

    2015-01-01

    Salvia miltiorrhiza Bunge (Labiatae) is an emerging model plant for traditional medicine, and tanshinones are among the pharmacologically active constituents of this plant. Although extensive chemical and pharmaceutical studies of these compounds have been performed, studies on the basic helix-loop-helix (bHLH) transcription factors that regulate tanshinone biosynthesis are limited. In our study, 127 bHLH transcription factor genes were identified in the genome of S. miltiorrhiza, and phylogenetic analysis indicated that these SmbHLHs could be classified into 25 subfamilies. A total of 19 sequencing libraries were constructed for expression pattern analyses using RNA-Seq. Based on gene-specific expression patterns and up-regulated expression patterns in response to MeJA treatment, 7 bHLH genes were revealed as potentially involved in the regulation of tanshinone biosynthesis. Among them, the gene expression of SmbHLH37, SmbHLH74 and SmbHLH92 perfectly matches the accumulation pattern of tanshinone biosynthesis in S. miltiorrhiza. Our results provide a foundation for understanding the molecular basis and regulatory mechanisms of bHLH transcription factors in S. miltiorrhiza. PMID:26174967

  11. Genetic basis for glandular trichome formation in cotton.

    PubMed

    Ma, Dan; Hu, Yan; Yang, Changqing; Liu, Bingliang; Fang, Lei; Wan, Qun; Liang, Wenhua; Mei, Gaofu; Wang, Lingjian; Wang, Haiping; Ding, Linyun; Dong, Chenguang; Pan, Mengqiao; Chen, Jiedan; Wang, Sen; Chen, Shuqi; Cai, Caiping; Zhu, Xiefei; Guan, Xueying; Zhou, Baoliang; Zhu, Shuijin; Wang, Jiawei; Guo, Wangzhen; Chen, Xiaoya; Zhang, Tianzhen

    2016-01-01

    Trichomes originate from epidermal cells and can be classified as either glandular or non-glandular. Gossypium species are characterized by the presence of small and darkly pigmented lysigenous glands that contain large amounts of gossypol. Here, using a dominant glandless mutant, we characterize GoPGF, which encodes a basic helix-loop-helix domain-containing transcription factor, that we propose is a positive regulator of gland formation. Silencing GoPGF leads to a completely glandless phenotype. A single nucleotide insertion in GoPGF, introducing a premature stop codon is found in the duplicate recessive glandless mutant (gl2gl3). The characterization of GoPGF helps to unravel the regulatory network of glandular structure biogenesis, and has implications for understanding the production of secondary metabolites in glands. It also provides a potential molecular basis to generate glandless seed and glanded cotton to not only supply fibre and oil but also provide a source of protein for human consumption. PMID:26795254

  12. CD26-mediated regulation of periostin expression contributes to migration and invasion of malignant pleural mesothelioma cells.

    PubMed

    Komiya, Eriko; Ohnuma, Kei; Yamazaki, Hiroto; Hatano, Ryo; Iwata, Satoshi; Okamoto, Toshihiro; Dang, Nam H; Yamada, Taketo; Morimoto, Chikao

    2014-05-16

    Malignant pleural mesothelioma (MPM) is an aggressive malignancy arising from mesothelial lining of pleura. It is generally associated with a history of asbestos exposure and has a very poor prognosis, partly due to the lack of a precise understanding of the molecular mechanisms associated with its malignant behavior. In the present study, we expanded on our previous studies on the enhanced motility and increased CD26 expression in MPM cells, with a particular focus on integrin adhesion molecules. We found that expression of CD26 upregulates periostin secretion by MPM cells, leading to enhanced MPM cell migratory and invasive activity. Moreover, we showed that upregulation of periostin expression results from the nuclear translocation of the basic helix-loop-helix transcription factor Twist1, a process that is mediated by CD26-associated activation of Src phosphorylation. While providing new and profound insights into the molecular mechanisms involved in MPM biology, these findings may also lead to the development of novel therapeutic strategies for MPM. PMID:24747072

  13. Multidirectional differentiation of Achaete-Scute homologue-1-defined progenitors in lung development and injury repair.

    PubMed

    Li, Yan; Linnoila, R Ilona

    2012-12-01

    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

  14. The Transcription Factor Atonal homolog 8 Regulates Gata4 and Friend of Gata-2 during Vertebrate Development

    PubMed Central

    Rawnsley, David R.; Xiao, Jiping; Lee, John S.; Liu, Xi; Mericko-Ishizuka, Patricia; Kumar, Vinayak; He, Jie; Basu, Arindam; Lu, MinMin; Lynn, Francis C.; Pack, Michael; Gasa, Rosa; Kahn, Mark L.

    2013-01-01

    GATA and Friend of GATA (FOG) form a transcriptional complex that plays a key role in cardiovascular development in both fish and mammals. In the present study we demonstrate that the basic helix-loop-helix transcription factor Atonal homolog 8 (Atoh8) is required for development of the heart in fish but not in mice. Genetic studies reveal that Atoh8 interacts specifically with Gata4 and Fog1 during development of the heart and swim bladder in the fish. Biochemical studies reveal that ATOH8, GATA4, and FOG2 associate in a single complex in vitro. In contrast to fish, ATOH8-deficient mice exhibit normal cardiac development and loss of ATOH8 does not alter cardiac development in Gata4+/− mice. This species difference in the role of ATOH8 is explained in part by LacZ and GFP reporter alleles that reveal restriction of Atoh8 expression to atrial but not ventricular myocardium in the mouse. Our findings identify ATOH8 as a novel regulator of GATA-FOG function that is required for cardiac development in the fish but not the mouse. Whether ATOH8 modulates GATA-FOG function at other sites or in more subtle ways in mammals is not yet known. PMID:23836893

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

    PubMed Central

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

    2010-01-01

    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

  16. Selection of human single domain antibodies recognizing the CMYC protein using enhanced intracellular antibody capture.

    PubMed

    Zeng, J; Li, H C; Tanaka, T; Rabbitts, T H

    2015-11-01

    Protein functions that are mediated by interaction with other proteins (protein-protein interactions, PPI) are important for normal cell biology and also in disease. Molecules that can interfere with PPI are required as laboratory tools to dissect function, as lead drug surrogates for target validation and as templates for drug discovery. We describe enhanced developments to Intracellular Antibody Capture (IAC) technology that can select antibody fragments able to interact with targets in cells. This is illustrated by the isolation of single heavy chain variable region domains binding to the basic-helix-loop-helix and leucine zipper region of the CMYC oncogenic protein. The enhanced IAC (eIAC) methodology deploys screening in yeast cells of a single diverse library initially with randomization only of CDR3. Further sequential randomization of CDR2 and CDR1 of three independently selected anti-CMYC clones illustrates an in vivo affinity maturation process. This concise eIAC approach facilitates the rapid selection of antibody fragments to explore the proteome interaction spectrum of mammalian cells and disease targeting. PMID:26319394

  17. C. elegans SoxB genes are dispensable for embryonic neurogenesis but required for terminal differentiation of specific neuron types.

    PubMed

    Vidal, Berta; Santella, Anthony; Serrano-Saiz, Esther; Bao, Zhirong; Chuang, Chiou-Fen; Hobert, Oliver

    2015-07-15

    Neurogenesis involves deeply conserved patterning molecules, such as the proneural basic helix-loop-helix transcription factors. Sox proteins and specifically members of the SoxB and SoxC groups are another class of conserved transcription factors with an important role in neuronal fate commitment and differentiation in various species. In this study, we examine the expression of all five Sox genes of the nematode C. elegans and analyze the effect of null mutant alleles of all members of the SoxB and SoxC groups on nervous system development. Surprisingly, we find that, unlike in other systems, neither of the two C. elegans SoxB genes sox-2 (SoxB1) and sox-3 (SoxB2), nor the sole C. elegans SoxC gene sem-2, is broadly expressed throughout the embryonic or adult nervous system and that all three genes are mostly dispensable for embryonic neurogenesis. Instead, sox-2 is required to maintain the developmental potential of blast cells that are generated in the embryo but divide only postembryonically to give rise to differentiated neuronal cell types. Moreover, sox-2 and sox-3 have selective roles in the terminal differentiation of specific neuronal cell types. Our findings suggest that the common themes of SoxB gene function across phylogeny lie in specifying developmental potential and, later on, in selectively controlling terminal differentiation programs of specific neuron types, but not in broadly controlling neurogenesis. PMID:26153233

  18. Identification of Id2 as a Globin Regulatory Protein by Representational Difference Analysis of K562 Cells Induced To Express γ-Globin with a Fungal Compound

    PubMed Central

    Holmes, Melissa L.; Haley, John D.; Cerruti, Loretta; Zhou, Wen-lai; Zogos, Helen; Smith, David E.; Cunningham, John M.; Jane, Stephen M.

    1999-01-01

    A fungus-derived compound (OSI-2040) which induces fetal globin expression in the absence of erythroid cell differentiation was identified in a high-throughput drug discovery program. We utilized this compound to isolate γ-globin regulatory genes that are differentially expressed in OSI-2040-induced and uninduced cells in the human erythroleukemia cell line K562. Representational difference analysis (RDA) of cDNA revealed several genes that were significantly up- or down-regulated in OSI-2040-induced cells. One gene whose expression was markedly enhanced was the gene for the helix-loop-helix (HLH) transcription factor Id2. Southern analysis of RDA amplicons demonstrated progressive enrichment of Id2 with each successive subtraction of uninduced cDNA from induced cDNA. Northern analysis of OSI-2040-induced K562 cells confirmed that Id2 expression was directly up-regulated coordinately with γ-globin. Analysis of other inducers of fetal globin demonstrated up-regulation of Id2 with sodium butyrate but not with hemin. Retrovirus-mediated overexpression of Id2 in K562 cells reproduced the enhancement of endogenous globin expression observed with OSI-2040 induction. Functional assays demonstrated that an E-box element in hypersensitivity site 2 is required for Id2-dependent enhancement of γ-promoter activity. Protein binding studies suggest that alterations in E-box site occupancy by basic HLH proteins may influence this activity, thus expanding the potential role of these factors in globin gene regulation. PMID:10330158

  19. A Steroid Receptor Coactivator Acts as the DNA-binding Partner of the Methoprene-tolerant Protein in Regulating Juvenile Hormone Response Genes

    PubMed Central

    Li, Meng; Liu, Pengcheng; Wiley, Jessica D.; Ojani, Reyhaneh; Bevan, David R.; Li, Jianyong; Zhu, Jinsong

    2014-01-01

    Methoprene-tolerant (Met) protein is a juvenile hormone (JH) receptor in insects. JH-bound Met forms a complex with the ?Ftz-F1-interacting steroid receptor coactivator (FISC) and together they regulate JH response genes in mosquitoes. Both proteins contain basic-helix-loop-helix (bHLH) and PAS motifs. Here we demonstrated that FISC is the obligatory partner of Met for binding to JH-response elements (JHREs). Met or FISC alone could not bind a previously characterized JHRE, while formation of the Met-FISC complex was necessary and sufficient to bind to the JHRE. This binding required participation of the DNA-binding domains of both Met and FISC. The optimal DNA sequence recognized by Met and FISC contained a core consensus sequence GCACGTG. While formation of the Met-FISC complex in mosquito cells was induced by JH, heterodimerization and DNA binding of bacterially expressed Met and FISC were JH-independent, implying that additional mosquito proteins were required to modulate formation of the receptor complex. PMID:25004255

  20. A wheat R2R3-MYB protein PURPLE PLANT1 (TaPL1) functions as a positive regulator of anthocyanin biosynthesis.

    PubMed

    Shin, Dong Ho; Choi, Myoung-Goo; Kang, Chon-Sik; Park, Chul-Soo; Choi, Sang-Bong; Park, Youn-Il

    2016-01-15

    Transcriptional activation of anthocyanin biosynthesis genes in vegetative tissues of monocotyledonous plants is mediated by cooperative activity of one component from each of the following two transcription factor families: MYB encoded by PURPLE PLANT1/COLORED ALEURONE1 (PL1/C1), and basic helix-loop-helix (bHLH) encoded by RED/BOOSTER (R1/B1). In the present study, putative PL cDNA was cloned from the wheat (Triticum aestivum) cultivar Iksan370, which preferentially expresses anthocyanins in coleoptiles. Phylogenetic tree analysis of deduced amino acid sequences showed that a putative TaPL1 is highly homologous to barley (Hordeum vulgare) HvPL1, but is distinct from wheat TaC1. Transgenic Arabidopsis thaliana stably expressing putative TaPL1 accumulated anthocyanin pigments in leaves and up-regulated structural genes involved in both early and late anthocyanin biosynthesis steps. TaPL1 transcript levels in Iksan370 were more prominent in vegetative tissues such as young coleoptiles than in reproductive tissues such as spikelets. TaPL1 expression was significantly up-regulated by environmental stresses including cold, salt, and light, which are known to induce anthocyanin accumulation. These combined results suggest that TaPL1 is an active positive regulator of anthocyanin biosynthesis in wheat coleoptiles. PMID:26692488

  1. Drosophila Hey is a target of Notch in asymmetric divisions during embryonic and larval neurogenesis

    PubMed Central

    Monastirioti, Maria; Giagtzoglou, Nikolaos; Koumbanakis, Konstantinos A.; Zacharioudaki, Evanthia; Deligiannaki, Myrto; Wech, Irmgard; Almeida, Mara; Preiss, Anette; Bray, Sarah; Delidakis, Christos

    2010-01-01

    bHLH-O proteins are a subfamily of the basic-helix-loop-helix transcription factors characterized by an ‘Orange’ protein-protein interaction domain. Typical members are the Hairy/E(spl), or Hes, proteins, well studied in their ability, among others, to suppress neuronal differentiation in both invertebrates and vertebrates. Hes proteins are often effectors of Notch signalling. In vertebrates, another bHLH-O protein group, the Hey proteins, have also been shown to be Notch targets and to interact with Hes. We have studied the single Drosophila Hey orthologue. We show that it is primarily expressed in a subset of newly born neurons, which receive Notch signalling during their birth. Unlike in vertebrates, however, Hey is not expressed in precursor cells and does not block neuronal differentiation. It rather promotes one of two alternative fates that sibling neurons adopt at birth. Although in the majority of cases Hey is a Notch target, it is also expressed independently of Notch in some lineages, most notably the larval mushroom body. The availability of Hey as a Notch readout has allowed us to study Notch signalling during the genesis of secondary neurons in the larval central nervous system. PMID:20040486

  2. Members of an R2R3-MYB transcription factor family in Petunia are developmentally and environmentally regulated to control complex floral and vegetative pigmentation patterning.

    PubMed

    Albert, Nick W; Lewis, David H; Zhang, Huaibi; Schwinn, Kathy E; Jameson, Paula E; Davies, Kevin M

    2011-03-01

    We present an investigation of anthocyanin regulation over the entire petunia plant, determining the mechanisms governing complex floral pigmentation patterning and environmentally induced vegetative anthocyanin synthesis. DEEP PURPLE (DPL) and PURPLE HAZE (PHZ) encode members of the R2R3-MYB transcription factor family that regulate anthocyanin synthesis in petunia, and control anthocyanin production in vegetative tissues and contribute to floral pigmentation. In addition to these two MYB factors, the basic helix-loop-helix (bHLH) factor ANTHOCYANIN1 (AN1) and WD-repeat protein AN11, are also essential for vegetative pigmentation. The induction of anthocyanins in vegetative tissues by high light was tightly correlated to the induction of transcripts for PHZ and AN1. Interestingly, transcripts for PhMYB27, a putative R2R3-MYB active repressor, were highly expressed during non-inductive shade conditions and repressed during high light. The competitive inhibitor PhMYBx (R3-MYB) was expressed under high light, which may provide feedback repression. In floral tissues DPL regulates vein-associated anthocyanin pigmentation in the flower tube, while PHZ determines light-induced anthocyanin accumulation on exposed petal surfaces (bud-blush). A model is presented suggesting how complex floral and vegetative pigmentation patterns are derived in petunia in terms of MYB, bHLH and WDR co-regulators. PMID:21235651

  3. ULTRAPETALA trxG Genes Interact with KANADI Transcription Factor Genes to Regulate Arabidopsis Gynoecium Patterning[C][W][OPEN

    PubMed Central

    Monfared, Mona M.; Shemyakina, Elena A.; Fletcher, Jennifer C.

    2014-01-01

    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

  4. Myrosin Idioblast Cell Fate and Development Are Regulated by the Arabidopsis Transcription Factor FAMA, the Auxin Pathway, and Vesicular Trafficking[W

    PubMed Central

    Li, Meng; Sack, Fred D.

    2014-01-01

    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

  5. Scaffold protein enigma homolog 1 overcomes the repression of myogenesis activation by inhibitor of DNA binding 2.

    PubMed

    Nakatani, Miyuki; Ito, Jumpei; Koyama, Riko; Iijima, Masumi; Yoshimoto, Nobuo; Niimi, Tomoaki; Kuroda, Shun'ichi; Maturana, Andrés D

    2016-05-27

    Enigma Homolog 1 (ENH1) is a scaffold protein for signaling proteins and transcription factors. Previously, we reported that ENH1 overexpression promotes the differentiation of C2C12 myoblasts. However, the molecular mechanism underlying the role of ENH1 in the C2C12 cells differentiation remains elusive. ENH1 was shown to inhibit the proliferation of neuroblastoma cells by sequestering Inhibitor of DNA binding protein 2 (Id2) in the cytosol. Id2 is a repressor of basic Helix-Loop-Helix transcription factors activity and prevents myogenesis. Here, we found that ENH1 overcome the Id2 repression of C2C12 cells myogenic differentiation and that ENH1 overexpression promotes mice satellite cells activation, the first step toward myogenic differentiation. In addition, we show that ENH1 interacted with Id2 in C2C12 cells and mice satellite cells. Collectively, our results suggest that ENH1 plays an important role in the activation of myogenesis through the repression of Id2 activity. PMID:27114303

  6. Arabidopsis MYC Transcription Factors Are the Target of Hormonal Salicylic Acid/Jasmonic Acid Cross Talk in Response to Pieris brassicae Egg Extract1[OPEN

    PubMed Central

    Schmiesing, André; Gouhier-Darimont, Caroline

    2016-01-01

    Arabidopsis (Arabidopsis thaliana) plants recognize insect eggs and activate the salicylic acid (SA) pathway. As a consequence, expression of defense genes regulated by the jasmonic acid (JA) pathway is suppressed and larval performance is enhanced. Cross talk between defense signaling pathways is common in plant-pathogen interactions, but the molecular mechanism mediating this phenomenon is poorly understood. Here, we demonstrate that egg-induced SA/JA antagonism works independently of the APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factor ORA59, which controls the ERF branch of the JA pathway. In addition, treatment with egg extract did not enhance expression or stability of JASMONATE ZIM-domain transcriptional repressors, and SA/JA cross talk did not involve JASMONATE ASSOCIATED MYC2-LIKEs, which are negative regulators of the JA pathway. Investigating the stability of MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that additively control jasmonate-related defense responses, we found that egg extract treatment strongly diminished MYC protein levels in an SA-dependent manner. Furthermore, we identified WRKY75 as a novel and essential factor controlling SA/JA cross talk. These data indicate that insect eggs target the MYC branch of the JA pathway and uncover an unexpected modulation of SA/JA antagonism depending on the biological context in which the SA pathway is activated. PMID:26884488

  7. PIFs: Systems Integrators in Plant Development[W

    PubMed Central

    Leivar, Pablo; Monte, Elena

    2014-01-01

    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

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

    PubMed Central

    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

    2011-01-01

    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

  9. The molecular basis for venation patterning of pigmentation and its effect on pollinator attraction in flowers of Antirrhinum.

    PubMed

    Shang, Yongjin; Venail, Julien; Mackay, Steve; Bailey, Paul C; Schwinn, Kathy E; Jameson, Paula E; Martin, Cathie R; Davies, Kevin M

    2011-01-01

    Pigment stripes associated with veins (venation) is a common flower colour pattern. The molecular genetics and function of venation were investigated in the genus Antirrhinum, in which venation is determined by Venosa (encoding an R2R3MYB transcription factor). Pollinator preferences were measured by field tests with Antirrhinum majus. Venosa function was examined using in situ hybridization and transient overexpression. The origin of the venation trait was examined by molecular phylogenetics. Venation and full-red flower colouration provide a comparable level of advantage for pollinator attraction relative to palely pigmented or white lines. Ectopic expression of Venosa confers pigmentation outside the veins. Venosa transcript is produced only in small areas of the corolla between the veins and the adaxial epidermis. Phylogenetic analyses suggest that venation patterning is an ancestral trait in Antirrhinum. Different accessions of three species with full-red pigmentation with or without venation patterning have been found. Epidermal-specific venation is defined through overlapping expression domains of the MYB (myoblastoma) and bHLH (basic Helix-Loop-Helix) co-regulators of anthocyanin biosynthesis, with the bHLH providing epidermal specificity and Venosa vein specificity. Venation may be the ancestral trait, with full-red pigmentation a derived, polyphyletic trait. Venation patterning is probably not fixed once species evolve full-red floral pigmentation. PMID:21039563

  10. FAMA Is an Essential Component for the Differentiation of Two Distinct Cell Types, Myrosin Cells and Guard Cells, in Arabidopsis[W

    PubMed Central

    Shirakawa, Makoto; Ueda, Haruko; Nagano, Atsushi J.; Shimada, Tomoo; Kohchi, Takayuki; Hara-Nishimura, Ikuko

    2014-01-01

    Brassicales plants, including Arabidopsis thaliana, have an ingenious two-compartment defense system, which sequesters myrosinase from the substrate glucosinolate and produces a toxic compound when cells are damaged by herbivores. Myrosinase is stored in vacuoles of idioblast myrosin cells. The molecular mechanism that regulates myrosin cell development remains elusive. Here, we identify the basic helix-loop-helix transcription factor FAMA as an essential component for myrosin cell development along Arabidopsis leaf veins. FAMA is known as a regulator of stomatal development. We detected FAMA expression in myrosin cell precursors in leaf primordia in addition to stomatal lineage cells. FAMA deficiency caused defects in myrosin cell development and in the biosynthesis of myrosinases THIOGLUCOSIDE GLUCOHYDROLASE1 (TGG1) and TGG2. Conversely, ectopic FAMA expression conferred myrosin cell characteristics to hypocotyl and root cells, both of which normally lack myrosin cells. The FAMA interactors ICE1/SCREAM and its closest paralog SCREAM2/ICE2 were essential for myrosin cell development. DNA microarray analysis identified 32 candidate genes involved in myrosin cell development under the control of FAMA. This study provides a common regulatory pathway that determines two distinct cell types in leaves: epidermal guard cells and inner-tissue myrosin cells. PMID:25304202

  11. Synthetic lethal analysis of Caenorhabditis elegans posterior embryonic patterning genes identifies conserved genetic interactions.

    PubMed

    Baugh, L Ryan; Wen, Joanne C; Hill, Andrew A; Slonim, Donna K; Brown, Eugene L; Hunter, Craig P

    2005-01-01

    Phenotypic robustness is evidenced when single-gene mutations do not result in an obvious phenotype. It has been suggested that such phenotypic stability results from 'buffering' activities of homologous genes as well as non-homologous genes acting in parallel pathways. One approach to characterizing mechanisms of phenotypic robustness is to identify genetic interactions, specifically, double mutants where buffering is compromised. To identify interactions among genes implicated in posterior patterning of the Caenorhabditis elegans embryo, we measured synthetic lethality following RNA interference of 22 genes in 15 mutant strains. A pair of homologous T-box transcription factors (tbx-8 and tbx-9) is found to interact in both C. elegans and C. briggsae, indicating that their compensatory function is conserved. Furthermore, a muscle module is defined by transitive interactions between the MyoD homolog hlh-1, another basic helix-loop-helix transcription factor, hnd-1, and the MADS-box transcription factor unc-120. Genetic interactions within a homologous set of genes involved in vertebrate myogenesis indicate broad conservation of the muscle module and suggest that other genetic modules identified in C. elegans will be conserved. PMID:15892873

  12. The DET1-COP1-HY5 pathway constitutes a multipurpose signaling module regulating plant photomorphogenesis and thermomorphogenesis.

    PubMed

    Delker, Carolin; Sonntag, Louisa; James, Geo Velikkakam; Janitza, Philipp; Ibañez, Carla; Ziermann, Henriette; Peterson, Tom; Denk, Kathrin; Mull, Steffi; Ziegler, Jörg; Davis, Seth Jon; Schneeberger, Korbinian; Quint, Marcel

    2014-12-24

    Developmental plasticity enables plants to respond to elevated ambient temperatures by adapting their shoot architecture. On the cellular level, the basic-helix-loop-helix (bHLH) transcription factor phytochrome interacting factor 4 (PIF4) coordinates this response by activating hormonal modules that in turn regulate growth. In addition to an unknown temperature-sensing mechanism, it is currently not understood how temperature regulates PIF4 activity. Using a forward genetic approach in Arabidopsis thaliana, we present extensive genetic evidence demonstrating that the de-etiolated 1 (DET1)-constitutive photomorphogenic 1 (COP1)-elongated hypocotyl 5 (HY5)-dependent photomorphogenesis pathway transcriptionally regulates PIF4 to coordinate seedling growth in response to elevated temperature. Our findings demonstrate that two of the most prevalent environmental cues, light and temperature, share a much larger set of signaling components than previously assumed. Similar to the toolbox concept in animal embryonic patterning, multipurpose signaling modules might have evolved in plants to translate various environmental stimuli into adaptational growth processes. PMID:25533339

  13. Origin of a Non-Clarke's Column Division of the Dorsal Spinocerebellar Tract and the Role of Caudal Proprioceptive Neurons in Motor Function.

    PubMed

    Yuengert, Rachel; Hori, Kei; Kibodeaux, Erin E; McClellan, Jacob X; Morales, Justin E; Huang, Teng-Wei P; Neul, Jeffrey L; Lai, Helen C

    2015-11-10

    Proprioception, the sense of limb and body position, is essential for generating proper movement. Unconscious proprioceptive information travels through cerebellar-projecting neurons in the spinal cord and medulla. The progenitor domain defined by the basic-helix-loop-helix (bHLH) transcription factor, ATOH1, has been implicated in forming these cerebellar-projecting neurons; however, their precise contribution to proprioceptive tracts and motor behavior is unknown. Significantly, we demonstrate that Atoh1-lineage neurons in the spinal cord reside outside Clarke's column (CC), a main contributor of neurons relaying hindlimb proprioception, despite giving rise to the anatomical and functional correlate of CC in the medulla, the external cuneate nucleus (ECu), which mediates forelimb proprioception. Elimination of caudal Atoh1-lineages results in mice with relatively normal locomotion but unable to perform coordinated motor tasks. Altogether, we reveal that proprioceptive nuclei in the spinal cord and medulla develop from more than one progenitor source, suggesting an avenue to uncover distinct proprioceptive functions. PMID:26527010

  14. The Clock gene clone and its circadian rhythms in Pelteobagrus vachelli

    NASA Astrophysics Data System (ADS)

    Qin, Chuanjie; Shao, Ting

    2015-05-01

    The Clock gene, a key molecule in circadian systems, is widely distributed in the animal kingdom. We isolated a 936-bp partial cDNA sequence of the Clock gene ( Pva-clock) from the darkbarbel catfish Pelteobagrus vachelli that exhibited high identity with Clock genes of other species of fish and animals (65%-88%). The putative domains included a basic helix-loop-helix (bHLH) domain and two period-ARNT-single-minded (PAS) domains, which were also similar to those in other species of fish and animals. Pva-Clock was primarily expressed in the brain, and was detected in all of the peripheral tissues sampled. Additionally, the pattern of Pva-Clock expression over a 24-h period exhibited a circadian rhythm in the brain, liver and intestine, with the acrophase at zeitgeber time 21:35, 23:00, and 23:23, respectively. Our results provide insight into the function of the molecular Clock of P. vachelli.

  15. Structure-based Inhibitor Design for the Intrinsically Disordered Protein c-Myc

    PubMed Central

    Yu, Chen; Niu, Xiaogang; Jin, Fan; Liu, Zhirong; Jin, Changwen; Lai, Luhua

    2016-01-01

    Intrinsically disordered proteins (IDPs) are associated with various diseases and have been proposed as promising drug targets. However, conventional structure-based approaches cannot be applied directly to IDPs, due to their lack of ordered structures. Here, we describe a novel computational approach to virtually screen for compounds that can simultaneously bind to different IDP conformations. The test system used c-Myc, an oncoprotein containing a disordered basic helix-loop-helix-leucine zipper (bHLH-LZ) domain that adopts a helical conformation upon binding to Myc-associated factor X (Max). For the virtual screen, we used three binding pockets in representative conformations of c-Myc370–409, which is part of the disordered bHLH-LZ domain. Seven compounds were found to directly bind c-Myc370–409 in vitro, and four inhibited the growth of the c-Myc-overexpressing cells by affecting cell cycle progression. Our approach of IDP conformation sampling, binding site identification, and virtual screening for compounds that can bind to multiple conformations provides a useful strategy for structure-based drug discovery targeting IDPs. PMID:26931396

  16. Interaction between the bHLH transcription factor FIT and ETHYLENE INSENSITIVE3/ETHYLENE INSENSITIVE3-LIKE1 reveals molecular linkage between the regulation of iron acquisition and ethylene signaling in Arabidopsis.

    PubMed

    Lingam, Sivasenkar; Mohrbacher, Julia; Brumbarova, Tzvetina; Potuschak, Thomas; Fink-Straube, Claudia; Blondet, Eddy; Genschik, Pascal; Bauer, Petra

    2011-05-01

    Understanding the regulation of key genes involved in plant iron acquisition is of crucial importance for breeding of micronutrient-enriched crops. The basic helix-loop-helix protein FER-LIKE FE DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT), a central regulator of Fe acquisition in roots, is regulated by environmental cues and internal requirements for iron at the transcriptional and posttranscriptional levels. The plant stress hormone ethylene promotes iron acquisition, but the molecular basis for this remained unknown. Here, we demonstrate a direct molecular link between ethylene signaling and FIT. We identified ETHYLENE INSENSITIVE3 (EIN3) and ETHYLENE INSENSITIVE3-LIKE1 (EIL1) in a screen for direct FIT interaction partners and validated their physical interaction in planta. We demonstrate that the ein3 eil1 transcriptome was affected to a greater extent upon iron deficiency than normal iron compared with the wild type. Ethylene signaling by way of EIN3/EIL1 was required for full-level FIT accumulation. FIT levels were reduced upon application of aminoethoxyvinylglycine and in the ein3 eil1 background. MG132 could restore FIT levels. We propose that upon ethylene signaling, FIT is less susceptible to proteasomal degradation, presumably due to a physical interaction between FIT and EIN3/EIL1. Increased FIT abundance then leads to the high level of expression of genes required for Fe acquisition. This way, ethylene is one of the signals that triggers Fe deficiency responses at the transcriptional and posttranscriptional levels. PMID:21586684

  17. Chromatin immunoselection defines a TAL-1 target gene.

    PubMed

    Cohen-Kaminsky, S; Maouche-Chrétien, L; Vitelli, L; Vinit, M A; Blanchard, I; Yamamoto, M; Peschle, C; Roméo, P H

    1998-09-01

    Despite the major functions of the basic helix-loop-helix transcription factor TAL-1 in hematopoiesis and T-cell leukemogenesis, no TAL-1 target gene has been identified. Using immunoprecipitation of genomic fragments bound to TAL-1 in the chromatin of murine erythro-leukemia (MEL) cells, we found that 10% of the immunoselected fragments contained a CAGATG or a CAGGTG E-box, followed by a GATA site. We studied one of these fragments containing two E-boxes, CAGATG and CAGGTC, followed by a GATA motif, and showed that TAL-1 binds to the CAGGTG E-box with an affinity modulated by the CAGATG or the GATA site, and that the CAGGTG-GATA motif exhibits positive transcriptional activity in MEL but not in HeLa cells. This immunoselected sequence is located within an intron of a new gene co-expressed with TAL-1 in endothelial and erythroid cells, but not expressed in fibroblasts or adult liver where no TAL-1 mRNA was detected. Finally, in vitro differentiation of embryonic stem cells towards the erythro/megakaryocytic pathways showed that the TAL-1 target gene expression followed TAL-1 and GATA-1 expression. These results establish that TAL-1 is likely to activate its target genes through a complex that binds an E-box-GATA motif and define the first gene regulated by TAL-1. PMID:9724651

  18. The SCL +40 enhancer targets the midbrain together with primitive and definitive hematopoiesis and is regulated by SCL and GATA proteins.

    PubMed

    Ogilvy, S; Ferreira, R; Piltz, S G; Bowen, J M; Göttgens, B; Green, A R

    2007-10-01

    The SCL/Tal-1 gene encodes a basic helix-loop-helix transcription factor with key roles in hematopoietic and neural development. SCL is expressed in, and required for, both primitive and definitive erythropoiesis. Thus far, we have identified only one erythroid SCL enhancer. Located 40 kb downstream of exon 1a, the +40 enhancer displays activity in primitive erythroblasts. We demonstrate here that a 3.7-kb fragment containing this element also targets expression to the midbrain, a known site of endogenous SCL expression. Although the 3.7-kb construct was active in primitive, but not definitive, erythroblasts, a larger 5.0-kb fragment, encompassing the 3.7-kb region, was active in both fetal and adult definitive hematopoietic cells. This included Ter119+ erythroid cells along with fetal liver erythroid and myeloid progenitors. Unlike two other SCL hematopoietic enhancers (+18/19 and -4), +40 enhancer transgenes were inactive in the endothelium. A conserved 400-bp core region, essential for both hematopoietic and midbrain +40 enhancer activity in embryos, relied on two GATA/E-box motifs and was bound in vivo by GATA-1 and SCL in erythroid cells. These results suggest a model in which the SCL +18/19 and/or -4 enhancers initiate SCL expression in early mesodermal derivatives capable of generating blood and endothelium, with subsequent activation of the +40 enhancer via an autoregulatory loop. PMID:17709394

  19. Wnt9a deficiency discloses a repressive role of Tcf7l2 on endocrine differentiation in the embryonic pancreas

    PubMed Central

    Pujadas, G.; Cervantes, S.; Tutusaus, A.; Ejarque, M.; Sanchez, L.; García, A.; Esteban, Y.; Fargas, L.; Alsina, B.; Hartmann, C.; Gomis, R.; Gasa, R.

    2016-01-01

    Transcriptional and signaling networks establish complex cross-regulatory interactions that drive cellular differentiation during development. Using microarrays we identified the gene encoding the ligand Wnt9a as a candidate target of Neurogenin3, a basic helix-loop-helix transcription factor that functions as a master regulator of pancreatic endocrine differentiation. Here we show that Wnt9a is expressed in the embryonic pancreas and that its deficiency enhances activation of the endocrine transcriptional program and increases the number of endocrine cells at birth. We identify the gene encoding the endocrine transcription factor Nkx2-2 as one of the most upregulated genes in Wnt9a-ablated pancreases and associate its activation to reduced expression of the Wnt effector Tcf7l2. Accordingly, in vitro studies confirm that Tcf7l2 represses activation of Nkx2-2 by Neurogenin3 and inhibits Nkx2-2 expression in differentiated β-cells. Further, we report that Tcf7l2 protein levels decline upon initiation of endocrine differentiation in vivo, disclosing the downregulation of this factor in the developing endocrine compartment. These findings highlight the notion that modulation of signalling cues by lineage-promoting factors is pivotal for controlling differentiation programs. PMID:26771085

  20. Tissue-Specific Regulation of Gibberellin Signaling Fine-Tunes Arabidopsis Iron-Deficiency Responses.

    PubMed

    Wild, Michael; Davière, Jean-Michel; Regnault, Thomas; Sakvarelidze-Achard, Lali; Carrera, Esther; Lopez Diaz, Isabel; Cayrel, Anne; Dubeaux, Guillaume; Vert, Grégory; Achard, Patrick

    2016-04-18

    Iron is an essential element for most living organisms. Plants acquire iron from the rhizosphere and have evolved different biochemical and developmental responses to adapt to a low-iron environment. In Arabidopsis, FIT encodes a basic helix-loop-helix transcription factor that activates the expression of iron-uptake genes in root epidermis upon iron deficiency. Here, we report that the gibberellin (GA)-signaling DELLA repressors contribute substantially in the adaptive responses to iron-deficient conditions. When iron availability decreases, DELLAs accumulate in the root meristem, thereby restraining root growth, while being progressively excluded from epidermal cells in the root differentiation zone. Such DELLA exclusion from the site of iron acquisition relieves FIT from DELLA-dependent inhibition and therefore promotes iron uptake. Consistent with this mechanism, expression of a non-GA-degradable DELLA mutant protein in root epidermis interferes with iron acquisition. Hence, spatial distribution of DELLAs in roots is essential to fine-tune the adaptive responses to iron availability. PMID:27093087

  1. Auxin signaling modules regulate maize inflorescence architecture.

    PubMed

    Galli, Mary; Liu, Qiujie; Moss, Britney L; Malcomber, Simon; Li, Wei; Gaines, Craig; Federici, Silvia; Roshkovan, Jessica; Meeley, Robert; Nemhauser, Jennifer L; Gallavotti, Andrea

    2015-10-27

    In plants, small groups of pluripotent stem cells called axillary meristems are required for the formation of the branches and flowers that eventually establish shoot architecture and drive reproductive success. To ensure the proper formation of new axillary meristems, the specification of boundary regions is required for coordinating their development. We have identified two maize genes, BARREN INFLORESCENCE1 and BARREN INFLORESCENCE4 (BIF1 and BIF4), that regulate the early steps required for inflorescence formation. BIF1 and BIF4 encode AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) proteins, which are key components of the auxin hormone signaling pathway that is essential for organogenesis. Here we show that BIF1 and BIF4 are integral to auxin signaling modules that dynamically regulate the expression of BARREN STALK1 (BA1), a basic helix-loop-helix (bHLH) transcriptional regulator necessary for axillary meristem formation that shows a striking boundary expression pattern. These findings suggest that auxin signaling directly controls boundary domains during axillary meristem formation and define a fundamental mechanism that regulates inflorescence architecture in one of the most widely grown crop species. PMID:26464512

  2. Signaling mechanisms of plant cryptochromes in Arabidopsis thaliana.

    PubMed

    Liu, Bobin; Yang, Zhaohe; Gomez, Adam; Liu, Bin; Lin, Chentao; Oka, Yoshito

    2016-03-01

    Cryptochromes (CRY) are flavoproteins that direct a diverse array of developmental processes in response to blue light in plants. Conformational changes in CRY are induced by the absorption of photons and result in the propagation of light signals to downstream components. In Arabidopsis, CRY1 and CRY2 serve both distinct and partially overlapping functions in regulating photomorphogenic responses and photoperiodic flowering. For example, both CRY1 and CRY2 regulate the abundance of transcription factors by directly reversing the activity of E3 ubiquitin ligase on CONSTITUTIVE PHOTOMORPHOGENIC 1 and SUPPRESSOR OF PHYA-105 1 complexes in a blue light-dependent manner. CRY2 also specifically governs a photoperiodic flowering mechanism by directly interacting with a transcription factor called CRYPTOCHROME-INTERACTING BASIC-HELIX-LOOP-HELIX. Recently, structure/function analysis of CRY1 revealed that the CONSTITUTIVE PHOTOMORPHOGENIC 1 independent pathway is also involved in CRY1-mediated inhibition of hypocotyl elongation. CRY1 and CRY2 thus not only share a common pathway but also relay light signals through distinct pathways, which may lead to altered developmental programs in plants. PMID:26810763

  3. The bHLH transcription factor BIS1 controls the iridoid branch of the monoterpenoid indole alkaloid pathway in Catharanthus roseus.

    PubMed

    Van Moerkercke, Alex; Steensma, Priscille; Schweizer, Fabian; Pollier, Jacob; Gariboldi, Ivo; Payne, Richard; Vanden Bossche, Robin; Miettinen, Karel; Espoz, Javiera; Purnama, Purin Candra; Kellner, Franziska; Seppänen-Laakso, Tuulikki; O'Connor, Sarah E; Rischer, Heiko; Memelink, Johan; Goossens, Alain

    2015-06-30

    Plants make specialized bioactive metabolites to defend themselves against attackers. The conserved control mechanisms are based on transcriptional activation of the respective plant species-specific biosynthetic pathways by the phytohormone jasmonate. Knowledge of the transcription factors involved, particularly in terpenoid biosynthesis, remains fragmentary. By transcriptome analysis and functional screens in the medicinal plant Catharanthus roseus (Madagascar periwinkle), the unique source of the monoterpenoid indole alkaloid (MIA)-type anticancer drugs vincristine and vinblastine, we identified a jasmonate-regulated basic helix-loop-helix (bHLH) transcription factor from clade IVa inducing the monoterpenoid branch of the MIA pathway. The bHLH iridoid synthesis 1 (BIS1) transcription factor transactivated the expression of all of the genes encoding the enzymes that catalyze the sequential conversion of the ubiquitous terpenoid precursor geranyl diphosphate to the iridoid loganic acid. BIS1 acted in a complementary manner to the previously characterized ethylene response factor Octadecanoid derivative-Responsive Catharanthus APETALA2-domain 3 (ORCA3) that transactivates the expression of several genes encoding the enzymes catalyzing the conversion of loganic acid to the downstream MIAs. In contrast to ORCA3, overexpression of BIS1 was sufficient to boost production of high-value iridoids and MIAs in C. roseus suspension cell cultures. Hence, BIS1 might be a metabolic engineering tool to produce sustainably high-value MIAs in C. roseus plants or cultures. PMID:26080427

  4. Wingless blocks bristle formation and morphogenetic furrow progression in the eye through repression of Daughterless.

    PubMed

    Cadigan, Kenneth M; Jou, Austin D; Nusse, Roel

    2002-07-01

    In the developing eye, wingless activity represses proneural gene expression (and thus interommatidial bristle formation) and positions the morphogenetic furrow by blocking its initiation in the dorsal and ventral regions of the presumptive eye. We provide evidence that wingless mediates both effects, at least in part, through repression of the basic helix-loop-helix protein Daughterless. daughterless is required for high proneural gene expression and furrow progression. Ectopic expression of wingless blocks Daughterless expression in the proneural clusters. This repression, and that of furrow progression, can be mimicked by an activated form of armadillo and blocked by a dominant negative form of pangolin/TCF. Placing daughterless under the control of a heterologous promoter blocks the ability of ectopic wingless to inhibit bristle formation and furrow progression. hedgehog and decapentapleigic could not rescue the wingless furrow progression block, indicating that wingless acts downstream of these genes. In contrast, Atonal and Scute, which are thought to heterodimerize with Daughterless to promote furrow progression and bristle formation, respectively, can block ectopic wingless action. These results are summarized in a model where daughterless is a major, but probably not the only, target of wingless action in the eye. PMID:12091309

  5. Verification at the protein level of the PIF4-mediated external coincidence model for the temperature-adaptive photoperiodic control of plant growth in Arabidopsis thaliana.

    PubMed

    Yamashino, Takafumi; Nomoto, Yuji; Lorrain, Séverine; Miyachi, Miki; Ito, Shogo; Nakamichi, Norihito; Fankhauser, Christian; Mizuno, Takeshi

    2013-03-01

    Plant circadian clock controls a wide variety of physiological and developmental events, which include the short-days (SDs)-specific promotion of the elongation of hypocotyls during de-etiolation and also the elongation of petioles during vegetative growth. In A. thaliana, the PIF4 gene encoding a phytochrome-interacting basic helix-loop-helix (bHLH) transcription factor plays crucial roles in this photoperiodic control of plant growth. According to the proposed external coincidence model, the PIF4 gene is transcribed precociously at the end of night specifically in SDs, under which conditions the protein product is stably accumulated, while PIF4 is expressed exclusively during the daytime in long days (LDs), under which conditions the protein product is degraded by the light-activated phyB and also the residual proteins are inactivated by the DELLA family of proteins. A number of previous reports provided solid evidence to support this coincidence model mainly at the transcriptional level of the PIF 4 and PIF4-traget genes. Nevertheless, the diurnal oscillation profiles of PIF4 proteins, which were postulated to be dependent on photoperiod and ambient temperature, have not yet been demonstrated. Here we present such crucial evidence on PIF4 protein level to further support the external coincidence model underlying the temperature-adaptive photoperiodic control of plant growth in A. thaliana. PMID:23299336

  6. Id4 functions downstream of Bmp signaling to restrict TCF function in endocardial cells during atrioventricular valve development.

    PubMed

    Ahuja, Suchit; Dogra, Deepika; Stainier, Didier Y R; Reischauer, Sven

    2016-04-01

    The atrioventricular canal (AVC) connects the atrial and ventricular chambers of the heart and its formation is critical for the development of the cardiac valves, chamber septation and formation of the cardiac conduction system. Consequently, problems in AVC formation can lead to congenital defects ranging from cardiac arrhythmia to incomplete cardiac septation. While our knowledge about early heart tube formation is relatively comprehensive, much remains to be investigated about the genes that regulate AVC formation. Here we identify a new role for the basic helix-loop-helix factor Id4 in zebrafish AVC valve development and function. id4 is first expressed in the AVC endocardium and later becomes more highly expressed in the atrial chamber. TALEN induced inactivation of id4 causes retrograde blood flow at the AV canal under heat induced stress conditions, indicating defects in AV valve function. At the molecular level, we found that id4 inactivation causes misexpression of several genes important for AVC and AV valve formation including bmp4 and spp1. We further show that id4 appears to control the number of endocardial cells that contribute to the AV valves by regulating Wnt signaling in the developing AVC endocardium. PMID:26892463

  7. Isolation and Characterization of Rice R Genes: Evidence for Distinct Evolutionary Paths in Rice and Maize

    PubMed Central

    Hu, J.; Anderson, B.; Wessler, S. R.

    1996-01-01

    R and B genes and their homologues encode basic helix-loop-helix (bHLH) transcriptional activators that regulate the anthocyanin biosynthetic pathway in flowering plants. In maize, R/B genes comprise a very small gene family whose organization reflects the unique evolutionary history and genome architecture of maize. To know whether the organization of the R gene family could provide information about the origins of the distantly related grass rice, we characterized members of the R gene family from rice Oryza sativa. Despite being a true diploid, O. sativa has at least two R genes. An active homologue (Ra) with extensive homology with other R genes is located at a position on chromosome 4 previously shown to be in synteny with regions of maize chromosomes 2 and 10 that contain the B and R loci, respectively. A second rice R gene (Rb) of undetermined function was identified on chromosome 1 and found to be present only in rice species with AA genomes. All non-AA species have but one R gene that is Ra-like. These data suggest that the common ancestor shared by maize and rice had a single R gene and that the small R gene families of grasses have arisen recently and independently. PMID:8849907

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

    PubMed Central

    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

    2014-01-01

    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

  9. MYC2: the master in action.

    PubMed

    Kazan, Kemal; Manners, John M

    2013-05-01

    Jasmonates (JAs) are plant hormones with essential roles in plant defense and development. The basic-helix-loop-helix (bHLH) transcription factor (TF) MYC2 has recently emerged as a master regulator of most aspects of the jasmonate (JA) signaling pathway in Arabidopsis. MYC2 coordinates JA-mediated defense responses by antagonistically regulating two different branches of the JA signaling pathway that determine resistance to pests and pathogens, respectively. MYC2 is required for induced systemic resistance (ISR) triggered by beneficial soil microbes while MYC2 function is targeted by pathogens during effector-mediated suppression of innate immunity in roots. Another notable function of MYC2 is the regulation of crosstalk between the signaling pathways of JA and those of other phytohormones such as abscisic acid (ABA), salicylic acid (SA), gibberellins (GAs), and auxin (IAA). MYC2 also regulates interactions between JA signaling and light, phytochrome signaling, and the circadian clock. MYC2 is involved in JA-regulated plant development, lateral and adventitious root formation, flowering time, and shade avoidance syndrome. Related bHLH TFs MYC3 and MYC4 also regulate both overlapping and distinct MYC2-regulated functions in Arabidopsis while MYC2 orthologs act as 'master switches' that regulate JA-mediated biosynthesis of secondary metabolites. Here, we briefly review recent studies that revealed mechanistic new insights into the mode of action of this versatile TF. PMID:23142764

  10. The Transcriptional Repressor MYB2 Regulates Both Spatial and Temporal Patterns of Proanthocyandin and Anthocyanin Pigmentation in Medicago truncatula[OPEN

    PubMed Central

    2015-01-01

    Accumulation of anthocyanins and proanthocyanidins (PAs) is limited to specific cell types and developmental stages, but little is known about how antagonistically acting transcriptional regulators work together to determine temporal and spatial patterning of pigmentation at the cellular level, especially for PAs. Here, we characterize MYB2, a transcriptional repressor regulating both anthocyanin and PA biosynthesis in the model legume Medicago truncatula. MYB2 was strongly upregulated by MYB5, a major regulator of PA biosynthesis in M. truncatula and a component of MYB-basic helix loop helix-WD40 (MBW) activator complexes. Overexpression of MYB2 abolished anthocyanin and PA accumulation in M. truncatula hairy roots and Arabidopsis thaliana seeds, respectively. Anthocyanin deposition was expanded in myb2 mutant seedlings and flowers accompanied by increased anthocyanin content. PA mainly accumulated in the epidermal layer derived from the outer integument in the M. truncatula seed coat, starting from the hilum area. The area of PA accumulation and ANTHOCYANIDIN REDUCTASE expression was expanded into the seed body at the early stage of seed development in the myb2 mutant. Genetic, biochemical, and cell biological evidence suggests that MYB2 functions as part of a multidimensional regulatory network to define the temporal and spatial pattern of anthocyanin and PA accumulation linked to developmental processes. PMID:26410301

  11. ULTRAPETALA trxG genes interact with KANADI transcription factor genes to regulate Arabidopsis gynoecium patterning.

    PubMed

    Pires, Helena R; Monfared, Mona M; Shemyakina, Elena A; Fletcher, Jennifer C

    2014-11-01

    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

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

    PubMed

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

    2014-01-01

    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

  13. cDNA array reveals mechanosensitive genes in chondrocytic cells under hydrostatic pressure.

    PubMed

    Sironen, Reijo K; Karjalainen, Hannu M; Elo, Mika A; Kaarniranta, Kai; Törrönen, Kari; Takigawa, Masaharu; Helminen, Heikki J; Lammi, Mikko J

    2002-08-19

    Hydrostatic pressure (HP) has a profound effect on cartilage metabolism in normal and pathological conditions, especially in weight-bearing areas of the skeletal system. As an important component of overall load, HP has been shown to affect the synthetic capacity and well-being of chondrocytes, depending on the mode, duration and magnitude of pressure. In this study we examined the effect of continuous HP on the gene expression profile of a chondrocytic cell line (HCS-2/8) using a cDNA array containing 588 well-characterized human genes under tight transcriptional control. A total of 51 affected genes were identified, many of them not previously associated with mechanical stimuli. Among the significantly up-regulated genes were immediate-early genes, and genes involved in heat-shock response (hsp70, hsp40, hsp27), and in growth arrest (GADD45, GADD153, p21(Cip1/Waf1), tob). Markedly down-regulated genes included members of the Id family genes (dominant negative regulators of basic helix-loop-helix transcription factors), and cytoplasmic dynein light chain and apoptosis-related gene NIP3. These alterations in the expression profile induce a transient heat-shock gene response and activation of genes involved in growth arrest and cellular adaptation and/or differentiation. PMID:12183054

  14. A novel bHLH transcription factor PebHLH35 from Populus euphratica confers drought tolerance through regulating stomatal development, photosynthesis and growth in Arabidopsis.

    PubMed

    Dong, Yan; Wang, Congpeng; Han, Xiao; Tang, Sha; Liu, Sha; Xia, Xinli; Yin, Weilun

    2014-07-18

    Plant basic helix-loop-helix (bHLH) transcription factors (TFs) are involved in a variety of physiological processes including the regulation of plant responses to various abiotic stresses. However, few drought-responsive bHLH family members in Populus have been reported. In this study, a novel bHLH gene (PebHLH35) was cloned from Populus euphratica. Expression analysis in P. euphratica revealed that PebHLH35 was induced by drought and abscisic acid. Subcellular localization studies using a PebHLH35-GFP fusion showed that the protein was localized to the nucleus. Ectopic overexpression of PebHLH35 in Arabidopsis resulted in a longer primary root, more leaves, and a greater leaf area under well-watered conditions compared with vector control plants. Notably, PebHLH35 overexpression lines showed enhanced tolerance to water-deficit stress. This finding was supported by anatomical and physiological analyses, which revealed a reduced stomatal density, stomatal aperture, transpiration rate, and water loss, and a higher chlorophyll content and photosynthetic rate. Our results suggest that PebHLH35 functions as a positive regulator of drought stress responses by regulating stomatal density, stomatal aperture, photosynthesis and growth. PMID:24909687

  15. Characterization of MxFIT, an iron deficiency induced transcriptional factor in Malus xiaojinensis.

    PubMed

    Yin, Lili; Wang, Yi; Yuan, Mudan; Zhang, Xinzhong; Xu, Xuefeng; Han, Zhenhai

    2014-02-01

    Iron deficiency often results in nutritional disorder in fruit trees. Transcription factors play an important role in the regulation of iron uptake. In this study, we isolated an iron deficiency response transcription factor gene, MxFIT, from an iron-efficient apple genotype of Malus xiaojinensis. MxFIT encoded a basic helix-loop-helix protein and contained a 966 bp open reading frame. MxFIT protein was targeted to the nucleus in onion epidermal cells and showed strong transcriptional activation in yeast cells. Spatiotemporal expression analysis revealed that MxFIT was up-regulated in roots under iron deficiency at both mRNA and protein levels, while almost no expression was detected in leaves irrespective of iron supply. Ectopic expression of MxFIT resulted in enhanced iron deficiency responses in Arabidopsis under iron deficiency and stronger resistance to iron deficiency. Thus, MxFIT might be involved in iron uptake and plays an important role in iron deficiency response. PMID:24389022

  16. PRMT1 Is a Novel Regulator of Epithelial-Mesenchymal-Transition in Non-small Cell Lung Cancer*

    PubMed Central

    Avasarala, Sreedevi; Van Scoyk, Michelle; Karuppusamy Rathinam, Manoj Kumar; Zerayesus, Sereke; Zhao, Xiangmin; Zhang, Wei; Pergande, Melissa R.; Borgia, Jeffrey A.; DeGregori, James; Port, J. David; Winn, Robert A.; Bikkavilli, Rama Kamesh

    2015-01-01

    Protein arginine methyl transferase 1 (PRMT1) was shown to be up-regulated in cancers and important for cancer cell proliferation. However, the role of PRMT1 in lung cancer progression and metastasis remains incompletely understood. In the present study, we show that PRMT1 is an important regulator of epithelial-mesenchymal transition (EMT), cancer cell migration, and invasion, which are essential processes during cancer progression, and metastasis. Additionally, we have identified Twist1, a basic helix-loop-helix transcription factor and a well-known E-cadherin repressor, as a novel PRMT1 substrate. Taken together, we show that PRMT1 is a novel regulator of EMT and arginine 34 (Arg-34) methylation of Twist1 as a unique “methyl arginine mark” for active E-cadherin repression. Therefore, targeting PRMT1-mediated Twist1 methylation might represent a novel strategy for developing new anti-invasive/anti-metastatic drugs. Moreover, methylated Twist1 (Arg-34), as such, could also emerge as a potential important biomarker for lung cancer. PMID:25847239

  17. E Proteins regulate osteoclast maturation and survival

    PubMed Central

    Long, Courtney L.; Berry, William L.; Zhao, Ying; Sun, Xiao-Hong; Humphrey, Mary Beth

    2012-01-01

    Osteoclasts are bone specific polykarons derived from myeloid precursors under the stimulation of MCSF and RANKL. E proteins are basic helix-loop-helix (bHLH) transcription factors that modulate lymphoid versus myeloid cell fate decisions. To study the role of E proteins in osteoclasts, myeloid specific E protein gain-of-function transgenic mice were generated. These mice have high bone mass due to decreased osteoclast numbers and increased osteoclast apoptosis leading to overall reductions in resorptive capacity. The molecular mechanism of decreased osteoclast numbers and resorption is due, in part, to elevated expression of CD38, a regulator of intracellular calcium pools with known anti-osteoclastogenic properties, which increases sensitivity to apoptosis. In vivo, exogenous RANKL stimulation can overcome this inhibition to drive osteoclastogenesis and bone loss. In vitro derived ET2 osteoclasts are more spread and more numerous with increases in RANK, TREM2, and NFATc1 compared to wild type. However, their resorptive capacity does not increase accordingly. Thus, E proteins participate in osteoclast maturation and survival in homeostatic bone remodeling. PMID:22807064

  18. Conserved regulatory mechanism controls the development of cells with rooting functions in land plants.

    PubMed

    Tam, Thomas Ho Yuen; Catarino, Bruno; Dolan, Liam

    2015-07-21

    Land plants develop filamentous cells-root hairs, rhizoids, and caulonemata-at the interface with the soil. Members of the group XI basic helix-loop-helix (bHLH) transcription factors encoded by LOTUS JAPONICUS ROOTHAIRLESS1-LIKE (LRL) genes positively regulate the development of root hairs in the angiosperms Lotus japonicus, Arabidopsis thaliana, and rice (Oryza sativa). Here we show that auxin promotes rhizoid and caulonema development by positively regulating the expression of PpLRL1 and PpLRL2, the two LRL genes in the Physcomitrella patens genome. Although the group VIII bHLH proteins, AtROOT HAIR DEFECTIVE6 and AtROOT HAIR DEFECTIVE SIX-LIKE1, promote root-hair development by positively regulating the expression of AtLRL3 in A. thaliana, LRL genes promote rhizoid development independently of PpROOT HAIR DEFECTIVE SIX-LIKE1 and PpROOT HAIR DEFECITVE SIX-LIKE2 (PpRSL1 and PpRSL2) gene function in P. patens. Together, these data demonstrate that both LRL and RSL genes are components of an ancient auxin-regulated gene network that controls the development of tip-growing cells with rooting functions among most extant land plants. Although this network has diverged in the moss and the angiosperm lineages, our data demonstrate that the core network acted in the last common ancestor of the mosses and angiosperms that existed sometime before 420 million years ago. PMID:26150509

  19. OsPTF1, a Novel Transcription Factor Involved in Tolerance to Phosphate Starvation in Rice1[w

    PubMed Central

    Yi, Keke; Wu, Zhongchang; Zhou, Jie; Du, Liming; Guo, Longbiao; Wu, Yunrong; Wu, Ping

    2005-01-01

    We report here on a novel transcription factor with a basic helix-loop-helix domain for tolerance to inorganic phosphate (Pi) starvation in rice (Oryza sativa). The gene is designated OsPTF1. The expression of OsPTF1 is Pi starvation induced in roots while constitutively expressed in shoots, as shown by northern-blot analysis. Overexpression of OsPTF1 enhanced tolerance to Pi starvation in transgenic rice. Tillering ability, root and shoot biomass, and phosphorus content of transgenic rice plants were about 30% higher than those of the wild-type plants in Pi-deficient conditions in hydroponic experiments. In soil pot and field experiments, more than 20% increase in tiller number, panicle weight, and phosphorus content was observed in transgenic plants compared to wild-type plants at low-Pi levels. In Pi-deficient conditions, transgenic rice plants showed significantly higher total root length and root surface area, which results in a higher instantaneous Pi uptake rate over their wild-type counterparts. Microarray analysis for transgenic plants overexpressing OsPTF1 has been performed to investigate the downstream regulation of OsPTF1. PMID:16006597

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

    PubMed

    Li, Meng; Sack, Fred D

    2014-10-01

    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

  1. Genome-wide association mapping to candidate polymorphism resolution in the unsequenced barley genome

    PubMed Central

    Cockram, James; White, Jon; Zuluaga, Diana L.; Smith, David; Comadran, Jordi; Macaulay, Malcolm; Luo, Zewei; Kearsey, Mike J.; Werner, Peter; Harrap, David; Tapsell, Chris; Liu, Hui; Hedley, Peter E.; Stein, Nils; Schulte, Daniela; Steuernagel, Burkhard; Marshall, David F.; Thomas, William T. B.; Ramsay, Luke; Mackay, Ian; Balding, David J.; Waugh, Robbie; O'Sullivan, Donal M.; Booer, Chris; Pike, Steve; Hamilton, Graeme; Jellis, Graham; Davies, Nigel; Ross, Anne; Bury, Paul; Habgood, Rodney; Klose, Steve; Vequaud, Dominique; Christerson, Therese; Brosnan, James; Newton, Adrian; Russell, Joanne; Shaw, Paul; Bayles, Rosemary; Wang, Minghui

    2010-01-01

    Although commonplace in human disease genetics, genome-wide association (GWA) studies have only relatively recently been applied to plants. Using 32 phenotypes in the inbreeding crop barley, we report GWA mapping of 15 morphological traits across ∼500 cultivars genotyped with 1,536 SNPs. In contrast to the majority of human GWA studies, we observe high levels of linkage disequilibrium within and between chromosomes. Despite this, GWA analysis readily detected common alleles of high penetrance. To investigate the potential of combining GWA mapping with comparative analysis to resolve traits to candidate polymorphism level in unsequenced genomes, we fine-mapped a selected phenotype (anthocyanin pigmentation) within a 140-kb interval containing three genes. Of these, resequencing the putative anthocyanin pathway gene HvbHLH1 identified a deletion resulting in a premature stop codon upstream of the basic helix-loop-helix domain, which was diagnostic for lack of anthocyanin in our association and biparental mapping populations. The methodology described here is transferable to species with limited genomic resources, providing a paradigm for reducing the threshold of map-based cloning in unsequenced crops. PMID:21115826

  2. 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.

    PubMed

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

    2014-05-01

    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-1α. 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

  3. MicroRNA 146 (Mir146) Modulates Spermatogonial Differentiation by Retinoic Acid in Mice1

    PubMed Central

    Huszar, Jessica M.; Payne, Christopher J.

    2012-01-01

    ABSTRACT Impaired biogenesis of microRNAs disrupts spermatogenesis and leads to infertility in male mice. Spermatogonial differentiation is a key step in spermatogenesis, yet the mechanisms that control this event remain poorly defined. In this study, we discovered microRNA 146 (Mir146) to be highly regulated during spermatogonial differentiation, a process dependent on retinoic acid (RA) signaling. Mir146 transcript levels were diminished nearly 180-fold in differentiating spermatogonia when compared with undifferentiated spermatogonia. Luciferase assays revealed the direct binding of Mir146 to the 3′ untranslated region of the mediator complex subunit 1 (Med1), a coregulator of retinoid receptors (RARs and RXRs). Overexpression of Mir146 in cultured undifferentiated spermatogonia reduced Med1 transcript levels, as well as those of differentiation marker kit oncogene (Kit). MED1 protein was also diminished. Conversely, inhibition of Mir146 increased the levels of Kit. When undifferentiated spermatogonia were exposed to RA, Mir146 was downregulated along with a marker for undifferentiated germ cells, zinc finger and BTB domain containing 16 (Zbtb16; Plzf); Kit was upregulated. Overexpression of Mir146 in RA-treated spermatogonia inhibited the upregulation of Kit, stimulated by retinoic acid gene 8 (Stra8), and spermatogenesis- and oogenesis-specific basic helix-loop-helix 2 (Sohlh2). Inhibition of Mir146 in RA-treated spermatogonia greatly enhanced the upregulation of these genes. We conclude that Mir146 modulates the effects of RA on spermatogonial differentiation. PMID:23221399

  4. Distinct and Shared Transcriptomes Are Regulated by Microphthalmia-Associated Transcription Factor Isoforms in Mast Cells1

    PubMed Central

    Shahlaee, Amir H.; Brandal, Stephanie; Lee, Youl-Nam; Jie, Chunfa; Takemoto, Clifford M.

    2008-01-01

    The Microphthalmia-associated transcription factor (Mitf) is an essential basic helix-loop-helix leucine zipper transcription factor for mast cell development. Mice deficient in Mitf harbor a severe mast cell deficiency, and Mitf-mutant mast cells cultured ex vivo display a number of functional defects. Therefore, an understanding of the genetic program regulated by Mitf may provide important insights into mast cell differentiation. Multiple, distinct isoforms of Mitf have been identified in a variety of cell types; we found that Mitf-a, Mitf-e, and Mitf-mc were the major isoforms expressed in mast cells. To determine the physiologic function of Mitf in mast cells, we restored expression of these isoforms in primary mast cells from Mitf−/−mice. We found that these isoforms restored granular morphology and integrin-mediated migration. By microarray analysis, proteases, signaling molecules, cell surface receptor, and transporters comprised the largest groups of genes up-regulated by all isoforms. Furthermore, we found that isoforms also regulated distinct genes sets, suggesting separable biological activities. This work defines the transcriptome regulated by Mitf in mast cells and supports its role as master regulator of mast cell differentiation. Expression of multiple isoforms of this transcription factor may provide for redundancy of biological activities while also allowing diversity of function. PMID:17182576

  5. A Light-Regulated Genetic Module Was Recruited to Carpel Development in Arabidopsis following a Structural Change to SPATULA[W

    PubMed Central

    Reymond, Mathieu C.; Brunoud, Géraldine; Chauvet, Aurélie; Martínez-Garcia, Jaime F.; Martin-Magniette, Marie-Laure; Monéger, Françoise; Scutt, Charles P.

    2012-01-01

    A key innovation of flowering plants is the female reproductive organ, the carpel. Here, we show that a mechanism that regulates carpel margin development in the model flowering plant Arabidopsis thaliana was recruited from light-regulated processes. This recruitment followed the loss from the basic helix-loop-helix transcription factor SPATULA (SPT) of a domain previously responsible for its negative regulation by phytochrome. We propose that the loss of this domain was a prerequisite for the light-independent expression in female reproductive tissues of a genetic module that also promotes shade avoidance responses in vegetative organs. Striking evidence for this proposition is provided by the restoration of wild-type carpel development to spt mutants by low red/far-red light ratios, simulating vegetation shade, which we show to occur via phytochrome B, PHYTOCHROME INTERACTING FACTOR4 (PIF4), and PIF5. Our data illustrate the potential of modular evolutionary events to generate rapid morphological change and thereby provide a molecular basis for neo-Darwinian theories that describe this nongradualist phenomenon. Furthermore, the effects shown here of light quality perception on carpel development lead us to speculate on the potential role of light-regulated mechanisms in plant organs that, like the carpel, form within the shade of surrounding tissues. PMID:22851763

  6. Perspective in chronic kidney disease: targeting hypoxia-inducible factor (HIF) as potential therapeutic approach.

    PubMed

    Deshmukh, Aaishwarya B; Patel, Jayvadan K; Prajapati, Ashish R; Shah, Shreya

    2012-01-01

    Tissue hypoxia is a pathologic feature of many human diseases like cancer, myocardial infarction, stroke, and kidney disease. Convincing data from clinical studies in patients with chronic renal failure point to chronic hypoxia of kidneys as the end result of multiple processes and mechanisms. In acute as well as chronic diseases, tissue hypoxia not only implies a risk of energy deprivation but also induces regulatory mechanisms with profound influence on gene expression. Moreover, once established, accumulating evidence points to this chronic hypoxia as the central player along with final common pathway to end-stage renal disease (ESRD). An evolutionarily preserved oxygen-sensing mechanism enables cells to adapt and maintain homeostasis under hypoxic conditions by transcriptional activation of a host of genes mediating metabolic adaptation, angiogenesis, energy conservation, erythropoiesis, in addition to cell survival. The endogenous oxygen-sensing mechanism incorporates hypoxia-inducible factors (HIFs) that hub cellular response to hypoxia and comprises a family of oxygen-sensitive basic helix-loop-helix proteins that control the cellular transcriptional response to hypoxia. Hypoxia-inducible factor 1 (HIF-1) is thus a significant mediator of physiological responses to acute and chronic hypoxia. Since HIF is activated to suboptimal levels in pathogenic renal states, therapeutic activation holds a promising novel and effective approach to the treatment of ESRD. Current insights into the regulation of HIF may augment the understanding of the role of hypoxia in renal failure progression and may unbolt new options to improve hypoxia tolerance and induce nephroprotection. PMID:22264075

  7. Opposite roles of MRF4 and MyoD in cell proliferation and myogenic differentiation

    SciTech Connect

    Jin Xun; Kim, Jong-Gun; Oh, Myung-Joo; Oh, Ho-Yeon; Sohn, Young-Woo; Pian, Xumin; Yin, Jin Long; Beck, Samuel; Lee, Namkyung; Son, Jeesoo; Kim, Hyunggee; Yan Changguo; Wang Jihui; Choi, Yun-Jaie; Whang, Kwang Youn

    2007-12-21

    The basic helix-loop-helix myogenic regulatory factors play critical roles in skeletal myogenesis. Among the myogenic regulatory factors (MRFs), MRF4 shows a biphasic expression pattern during the formation of myotomes, although its function remains unclear. In this study, we used BEF (spontaneously immortalized bovine embryonic fibroblast that shows myogenic differentiation by overexpression of MyoD) and C2C12 cells to investigate the function of MRF4. Ectopic expressions of MRF4 did not stimulate myogenic differentiation in the BEF and C2C12 cells, but did show a marked increase of cell proliferation, upregulation of cyclin E, and downregulation of p21{sup WAF1}. Furthermore, MRF4 was found to induce degradation of the MyoD protein, which acts as a transcriptional activator for p21{sup WAF1}, and thus indicates that MRF4 accelerates cell proliferation by suppressing MyoD-dependent p21{sup WAF1} expression. However, forced expression of MyoD in the MRF4-overexpressing cells inhibited cell proliferation and partially induced myogenic differentiation, which suggests that MyoD is a potential negative intercessor of MRF4 in the regulation of the cell cycle. Taken together, these results indicate that MRF4 and MyoD play competitive roles in myogenesis by stimulating cell proliferation and differentiation, respectively.

  8. Overexpression of a bHLH1 Transcription Factor of Pyrus ussuriensis Confers Enhanced Cold Tolerance and Increases Expression of Stress-Responsive Genes

    PubMed Central

    Jin, Cong; Huang, Xiao-San; Li, Kong-Qing; Yin, Hao; Li, Lei-Ting; Yao, Zheng-Hong; Zhang, Shao-Ling

    2016-01-01

    The basic helix-loop-helix (bHLH) transcription factors are involved in arrays of physiological and biochemical processes. However, knowledge concerning the functions of bHLHs in cold tolerance remains poorly understood. In this study, a PubHLH1 gene isolated from Pyrus ussuriensis was characterized for its function in cold tolerance. PubHLH1 was upregulated by cold, salt, and dehydration, with the greatest induction under cold conditions. PubHLH1 had the transactivational activity and localized in the nucleus. Ectopic expression of PubHLH1 in transgenic tobacco conferred enhanced tolerance to cold stress. The transgenic lines had higher survival rates, higher chlorophyll, higher proline contents, lower electrolyte leakages and MDA when compared with wild type (WT). In addition, transcript levels of eight genes associated with ROS scavenging, regulation, and stress defense were higher in the transgenic plants relative to the WT under the chilling stress. Taken together, these results demonstrated that PubHLH1 played a key role in cold tolerance and, at least in part, contributed to activation of stress-responsive genes. PMID:27092159

  9. Neuronal differentiation of human iPS cells induced by baicalin via regulation of bHLH gene expression.

    PubMed

    Morita, Akihiro; Soga, Kohei; Nakayama, Hironobu; Ishida, Torao; Kawanishi, Shosuke; Sato, Eisuke F

    2015-09-25

    Efficient differentiation is important for regenerative medicine based on pluripotent stem cells, including treatment of neurodegenerative disorders and trauma. Baicalin promotes neuronal differentiation of neural stem/progenitor cells of rats and mice. To evaluate the suitability of baicalin for neuronal differentiation of human iPS cells, we investigated whether it promotes neuronal differentiation in human iPS cells and monitored basic helix-loop-helix (bHLH) gene expression during neuronal differentiation. Baicalin promoted neuronal differentiation and inhibited glial differentiation, suggesting that baicalin can influence the neuronal fate decision in human iPS cells. Notch signaling, which is upstream of bHLH proteins, was not involved in baicalin-induced neuronal differentiation. Baicalin treatment did not down-regulate Hes1 gene expression, but it reduced Hes1 protein levels and up-regulated Ascl1 gene expression. Thus, baicalin promoted neuronal differentiation via modulation of bHLH transcriptional factors. Therefore, baicalin has potential to be used as a small-molecule drug for regenerative treatment of neurodegenerative disorders. PMID:26277393

  10. High incidence of T-cell tumors in E2A-null mice and E2A/Id1 double-knockout mice.

    PubMed Central

    Yan, W; Young, A Z; Soares, V C; Kelley, R; Benezra, R; Zhuang, Y

    1997-01-01

    The basic-helix-loop-helix (bHLH) proteins encoded by the E2A gene are broadly expressed transcription regulators which function through binding to the E-box enhancer sequences. The DNA binding activities of E2A proteins are directly inhibited upon dimerization with the Id1 gene product. It has been shown that disruption of the E2A gene leads to a complete block in B-lymphocyte development and a high frequency of neonatal death. We report here that nearly half of the surviving E2A-null mice develop acute T-cell lymphoma between 3 to 10 months of age. We further show that disruption of the Id1 gene improves the chance of postnatal survival of E2A-null mice, indicating that Id1 is a canonical negative regulator of E2A and that the unbalanced ratio of E2A to Id1 may contribute to the postnatal death of the E2A-null mice. However, the E2A/Id1 double-knockout mice still develop T-cell tumors once they reach the age of 3 months. This result suggests that E2A may be essential for maintaining the homeostasis of T lymphocytes during their constant renewal in adult life. PMID:9372963

  11. The role of Atonal factors in mechanosensory cell specification and function

    PubMed Central

    Cai, Tiantian; Groves, Andrew K.

    2015-01-01

    atonal genes are basic helix-loop-helix transcription factors that were first identified as regulating the formation of mechanoreceptors and photoreceptors in Drosophila. Isolation of vertebrate homologs of atonal genes has shown these transcription factors to play diverse roles in the development of neurons and their progenitors, gut epithelial cells and mechanosensory cells in the inner ear and skin. In this article, we review the molecular function and regulation of atonal genes and their targets, with particular emphasis on the function of Atoh1 in the development, survival and function of hair cells of the inner ear. We discuss cell-extrinsic signals that induce Atoh1 expression, and the transcriptional networks that regulate its expression during development. Finally, we discuss recent work showing how identification of Atoh1 target genes in the cerebellum, spinal cord and gut can be used to propose candidate Atoh1 targets in tissues such as the inner ear where cell numbers and biochemical material are limiting. PMID:25339580

  12. Interaction of shade avoidance and auxin responses: a role for two novel atypical bHLH proteins.

    PubMed

    Roig-Villanova, Irma; Bou-Torrent, Jordi; Galstyan, Anahit; Carretero-Paulet, Lorenzo; Portols, Sergi; Rodrguez-Concepcin, Manuel; Martnez-Garca, Jaime F

    2007-11-14

    Plants sense the presence of potentially competing nearby individuals as a reduction in the red to far-red ratio of the incoming light. In anticipation of eventual shading, a set of plant responses known as the shade avoidance syndrome (SAS) is initiated soon after detection of this signal by the phytochrome photoreceptors. Here we analyze the function of PHYTOCHROME RAPIDLY REGULATED1 (PAR1) and PAR2, two Arabidopsis thaliana genes rapidly upregulated after simulated shade perception. These genes encode two closely related atypical basic helix-loop-helix proteins with no previously assigned function in plant development. Using reverse genetic approaches, we show that PAR1 and PAR2 act in the nucleus to broadly control plant development, acting as negative regulators of a variety of SAS responses, including seedling elongation and photosynthetic pigment accumulation. Molecularly, PAR1 and PAR2 act as direct transcriptional repressors of two auxin-responsive genes, SMALL AUXIN UPREGULATED15 (SAUR15) and SAUR68. Additional results support that PAR1 and PAR2 function in integrating shade and hormone transcriptional networks, rapidly connecting phytochrome-sensed light changes with auxin responsiveness. PMID:17948056

  13. Deficits in trace fear memory in a mouse model of the schizophrenia risk gene TCF4.

    PubMed

    Brzózka, Magdalena M; Rossner, Moritz J

    2013-01-15

    The basic helix-loop-helix (bHLH) transcription factor TCF4 was confirmed in the combined analysis of several large genome-wide association studies (GWAS) as one of the rare highly replicated significant schizophrenia (SZ) susceptibility genes in large case-control cohorts. Focused genetic association studies showed that TCF4 influences verbal learning and memory, and modulates sensorimotor gating. Mice overexpressing Tcf4 in the forebrain (Tcf4tg) display cognitive deficits in hippocampus-dependent learning tasks and impairment of prepulse inhibition, a well-established endophenotype of SZ. The spectrum of cognitive deficits in SZ subjects, however, is broad and covers attention, working memory, and anticipation. Collectively, these higher order cognitive processes and the recall of remote memories are thought to depend mainly on prefrontal cortical networks. To further investigate cognitive disturbances in Tcf4tg mice, we employed the trace fear conditioning paradigm that requires attention and critically depends on the anterior cingulate cortex (ACC). We show that Tcf4tg mice display deficits in recent and remote trace fear memory and are impaired at anticipating aversive stimuli. We also assessed mRNA expression of the neuronal activity-regulated gene Fos in the ACC and hippocampus. Upon trace conditioning, Fos expression is reduced in Tcf4tg mice as compared to controls, which parallels cognitive impairments in this learning paradigm. Collectively, these data indicate that the reduced cognitive performance in Tcf4tg mice includes deficits at the level of attention and behavioral anticipation. PMID:23069005

  14. The purple cauliflower arises from activation of a MYB transcription factor.

    PubMed

    Chiu, Li-Wei; Zhou, Xiangjun; Burke, Sarah; Wu, Xianli; Prior, Ronald L; Li, Li

    2010-11-01

    Anthocyanins are responsible for the color of many flowers, fruits, and vegetables. An interesting and unique Purple (Pr) gene mutation in cauliflower (Brassica oleracea var botrytis) confers an abnormal pattern of anthocyanin accumulation, giving the striking mutant phenotype of intense purple color in curds and a few other tissues. To unravel the nature of the Pr mutation in cauliflower, we isolated the Pr gene via a combination of candidate gene analysis and fine mapping. Pr encoded a R2R3 MYB transcription factor that exhibited tissue-specific expression, consistent with an abnormal anthocyanin accumulation pattern in the mutant. Transgenic Arabidopsis (Arabidopsis thaliana) and cauliflower plants expressing the Pr-D allele recapitulated the mutant phenotype, confirming the isolation of the Pr gene. Up-regulation of Pr specifically activated a basic helix-loop-helix transcription factor and a subset of anthocyanin structural genes encoding flavonoid 3'-hydroxylase, dihydroflavonol 4-reductase, and leucoanthocyanidin dioxygenase to confer ectopic accumulation of pigments in the purple cauliflower. Our results indicate that the genetic variation including a Harbinger DNA transposon insertion in the upstream regulatory region of the Pr-D allele is responsible for the up-regulation of the Pr gene in inducing phenotypic change in the plant. The successful isolation of Pr provides important information on the regulatory control of anthocyanin biosynthesis in Brassica vegetables, and offers a genetic resource for development of new varieties with enhanced health-promoting properties and visual appeal. PMID:20855520

  15. An RNA virus-encoded zinc-finger protein acts as a plant transcription factor and induces a regulator of cell size and proliferation in two tobacco species.

    PubMed

    Lukhovitskaya, Nina I; Solovieva, Anna D; Boddeti, Santosh K; Thaduri, Srinivas; Solovyev, Andrey G; Savenkov, Eugene I

    2013-03-01

    Plant viruses cause a variety of diseases in susceptible hosts. The disease symptoms often include leaf malformations and other developmental abnormalities, suggesting that viruses can affect plant development. However, little is known about the mechanisms underlying virus interference with plant morphogenesis. Here, we show that a C-4 type zinc-finger (ZF) protein, p12, encoded by a carlavirus (chrysanthemum virus B) can induce cell proliferation, which results in hyperplasia and severe leaf malformation. We demonstrate that the p12 protein activates expression of a regulator of cell size and proliferation, designated upp-L (upregulated by p12), which encodes a transcription factor of the basic/helix-loop-helix family sufficient to cause hyperplasia. The induction of upp-L requires translocation of the p12 protein into the nucleus and ZF-dependent specific interaction with the conserved regulatory region in the upp-L promoter. Our results establish the role of the p12 protein in modulation of host cell morphogenesis. It is likely that other members of the conserved C-4 type ZF family of viral proteins instigate reprogramming of plant development by mimicking eukaryotic transcriptional activators. PMID:23482855

  16. AP4 is a mediator of epithelial–mesenchymal transition and metastasis in colorectal cancer

    PubMed Central

    Jackstadt, Rene; Röh, Simone; Neumann, Jens; Jung, Peter; Hoffmann, Reinhard; Horst, David; Berens, Christian; Bornkamm, Georg W.; Kirchner, Thomas; Menssen, Antje

    2013-01-01

    The basic helix-loop-helix transcription factor AP4/TFAP4/AP-4 is encoded by a c-MYC target gene and displays up-regulation concomitantly with c-MYC in colorectal cancer (CRC) and numerous other tumor types. Here a genome-wide characterization of AP4 DNA binding and mRNA expression was performed using a combination of microarray, genome-wide chromatin immunoprecipitation, next-generation sequencing, and bioinformatic analyses. Thereby, hundreds of induced and repressed AP4 target genes were identified. Besides many genes involved in the control of proliferation, the AP4 target genes included markers of stemness (LGR5 and CD44) and epithelial–mesenchymal transition (EMT) such as SNAIL, E-cadherin/CDH1, OCLN, VIM, FN1, and the Claudins 1, 4, and 7. Accordingly, activation of AP4 induced EMT and enhanced migration and invasion of CRC cells. Conversely, down-regulation of AP4 resulted in mesenchymal–epithelial transition and inhibited migration and invasion. In addition, AP4 induction was required for EMT, migration, and invasion caused by ectopic expression of c-MYC. Inhibition of AP4 in CRC cells resulted in decreased lung metastasis in mice. Elevated AP4 expression in primary CRC significantly correlated with liver metastasis and poor patient survival. These findings imply AP4 as a new regulator of EMT that contributes to metastatic processes in CRC and presumably other carcinomas. PMID:23752226

  17. CUL4 forms an E3 ligase with COP1 and SPA to promote light-induced degradation of PIF1.

    PubMed

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

    2015-01-01

    Plants undergo contrasting developmental programs in dark and light. Photomorphogenesis, a light-adapted programme is repressed in the dark by the synergistic actions of CUL4(COP1-SPA) E3 ubiquitin ligase and a subset of basic helix-loop-helix transcription factors called phytochrome interacting factors (PIFs). To promote photomorphogenesis, light activates the phytochrome family of sensory photoreceptors, which inhibits these repressors by poorly understood mechanisms. Here, we show that the CUL4(COP1-SPA) E3 ubiquitin ligase is necessary for the light-induced degradation of PIF1 in Arabidopsis. The light-induced ubiquitylation and subsequent degradation of PIF1 is reduced in the cop1, spaQ and cul4 backgrounds. COP1, SPA1 and CUL4 preferentially form complexes with the phosphorylated forms of PIF1 in response to light. The cop1 and spaQ seeds display strong hyposensitive response to far-red light-mediated seed germination and light-regulated gene expression. These data show a mechanism by which an E3 ligase attenuates its activity by degrading its cofactor in response to light. PMID:26037329

  18. Arabidopsis noncoding RNA mediates control of photomorphogenesis by red light.

    PubMed

    Wang, Yuqiu; Fan, Xiuduo; Lin, Fang; He, Guangming; Terzaghi, William; Zhu, Danmeng; Deng, Xing Wang

    2014-07-15

    Seedling photomorphogenesis is a sophisticated developmental process that is controlled by both the transcriptional and posttranscriptional regulation of gene expression. Here, we identify an Arabidopsis noncoding RNA, designated hidden treasure 1 (HID1), as a factor promoting photomorphogenesis in continuous red light (cR). We show that HID1 acts through phytochrome-interacting factor 3 (PIF3), which encodes a basic helix-loop-helix transcription factor known to be a key repressor of photomorphogenesis. Knockdown of HID1 in hid1 mutants leads to a significant increase in the expression of PIF3, which in turn drives the development of elongated hypocotyls in cR. We identified two major stem-loops in HID1 that are essential for its modulation of hypocotyl growth in cR-grown seedlings. Furthermore, our data reveal that HID1 is assembled into large nuclear protein-RNA complex(es) and that it associates with the chromatin of the first intron of PIF3 to repress its transcription. Strikingly, phylogenetic analysis reveals that many land plants have conserved homologs of HID1 and that its rice homolog can rescue the mutant phenotype when expressed in Arabidopsis hid1 mutants. We thus concluded that HID1 is a previously uncharacterized noncoding RNA whose function represents another layer of regulation in the precise control of seedling photomorphogenesis. PMID:24982146

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

    PubMed

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

    2014-06-20

    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

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

    PubMed

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

    2014-05-23

    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

  1. Arabidopsis HFR1 is a potential nuclear substrate regulated by the Xanthomonas type III effector XopD(Xcc8004).

    PubMed

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

    2015-01-01

    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

  2. HEMERA Couples the Proteolysis and Transcriptional Activity of PHYTOCHROME INTERACTING FACTORs in Arabidopsis Photomorphogenesis.

    PubMed

    Qiu, Yongjian; Li, Meina; Pasoreck, Elise K; Long, Lingyun; Shi, Yiting; Galvão, Rafaelo M; Chou, Conrad L; Wang, He; Sun, Amanda Y; Zhang, Yiyin C; Jiang, Anna; Chen, Meng

    2015-05-01

    Phytochromes (phys) are red and far-red photoreceptors that control plant development and growth by promoting the proteolysis of a family of antagonistically acting basic helix-loop-helix transcription factors, the PHYTOCHROME-INTERACTING FACTORs (PIFs). We have previously shown that the degradation of PIF1 and PIF3 requires HEMERA (HMR). However, the biochemical function of HMR and the mechanism by which it mediates PIF degradation remain unclear. Here, we provide genetic evidence that HMR acts upstream of PIFs in regulating hypocotyl growth. Surprisingly, genome-wide analysis of HMR- and PIF-dependent genes reveals that HMR is also required for the transactivation of a subset of PIF direct-target genes. We show that HMR interacts with all PIFs. The HMR-PIF interaction is mediated mainly by HMR's N-terminal half and PIFs' conserved active-phytochrome B binding motif. In addition, HMR possesses an acidic nine-amino-acid transcriptional activation domain (9aaTAD) and a loss-of-function mutation in this 9aaTAD impairs the expression of PIF target genes and the destruction of PIF1 and PIF3. Together, these in vivo results support a regulatory mechanism for PIFs in which HMR is a transcriptional coactivator binding directly to PIFs and the 9aaTAD of HMR couples the degradation of PIF1 and PIF3 with the transactivation of PIF target genes. PMID:25944101

  3. Environmental and seasonal influences on red raspberry anthocyanin antioxidant contents and identification of quantitative traits loci (QTL).

    PubMed

    Kassim, Angzzas; Poette, Julie; Paterson, Alistair; Zait, Dzeti; McCallum, Susan; Woodhead, Mary; Smith, Kay; Hackett, Christine; Graham, Julie

    2009-05-01

    Consumption of raspberries promotes human health through intake of pharmaceutically active antioxidants, including cyanidin and pelargonidin anthocyanins; products of flavonoid metabolism and also pigments conferring colour to fruit. Raspberry anthocyanin contents could be enhanced for nutritional health and quality benefits utilising DNA polymorphisms in modern marker assisted breeding. The objective was to elucidate factors determining anthocyanin production in these fruits. HPLC quantified eight anthocyanin cyanidin and pelargonidin glycosides: -3-sophoroside, -3-glucoside, -3-rutinoside and -3-glucosylrutinoside across two seasons and two environments in progeny from a cross between two Rubus subspecies, Rubus idaeus (cv. Glen Moy)xRubus strigosus (cv. Latham). Significant seasonal variation was detected across pigments less for different growing environments within seasons. Eight antioxidants mapped to the same chromosome region on linkage group (LG) 1, across both years and from fruits grown in field and under protected cultivation. Seven antioxidants also mapped to a region on LG 4 across years and for both growing sites. A chalcone synthase (PKS 1) gene sequence mapped to LG 7 but did not underlie the anthocyanin quantitative traits loci (QTL) identified. Other candidate genes including basic-helix-loop-helix (bHLH), NAM/CUC2-like protein and bZIP transcription factor underlying the mapped anthocyanins were identified. PMID:19156716

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

    PubMed Central

    Raft, Steven; Groves, Andrew K.

    2014-01-01

    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

  5. MondoA deficiency enhances sprint performance in mice.

    PubMed

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

    2014-11-15

    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 γ co-activator-1α (PGC-1α)-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

  6. A Conserved Network of Transcriptional Activators and Repressors Regulates Anthocyanin Pigmentation in Eudicots[C][W][OPEN

    PubMed Central

    Albert, Nick W.; Davies, Kevin M.; Lewis, David H.; Zhang, Huaibi; Montefiori, Mirco; Brendolise, Cyril; Boase, Murray R.; Ngo, Hanh; Jameson, Paula E.; Schwinn, Kathy E.

    2014-01-01

    Plants require sophisticated regulatory mechanisms to ensure the degree of anthocyanin pigmentation is appropriate to myriad developmental and environmental signals. Central to this process are the activity of MYB-bHLH-WD repeat (MBW) complexes that regulate the transcription of anthocyanin genes. In this study, the gene regulatory network that regulates anthocyanin synthesis in petunia (Petunia hybrida) has been characterized. Genetic and molecular evidence show that the R2R3-MYB, MYB27, is an anthocyanin repressor that functions as part of the MBW complex and represses transcription through its C-terminal EAR motif. MYB27 targets both the anthocyanin pathway genes and basic-helix-loop-helix (bHLH) ANTHOCYANIN1 (AN1), itself an essential component of the MBW activation complex for pigmentation. Other features of the regulatory network identified include inhibition of AN1 activity by the competitive R3-MYB repressor MYBx and the activation of AN1, MYB27, and MYBx by the MBW activation complex, providing for both reinforcement and feedback regulation. We also demonstrate the intercellular movement of the WDR protein (AN11) and R3-repressor (MYBx), which may facilitate anthocyanin pigment pattern formation. The fundamental features of this regulatory network in the Asterid model of petunia are similar to those in the Rosid model of Arabidopsis thaliana and are thus likely to be widespread in the Eudicots. PMID:24642943

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

    PubMed Central

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

    2014-01-01

    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

  8. Phylogenetic Analysis and Classification of the Fungal bHLH Domain

    PubMed Central

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

    2012-01-01

    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 www.fungalgenomics.ncsu.edu. PMID:22114358

  9. Nfat and miR-25 cooperate to reactivate the transcription factor Hand2 in heart failure.

    PubMed

    Dirkx, Ellen; Gladka, Monika M; Philippen, Leonne E; Armand, Anne-Sophie; Kinet, Virginie; Leptidis, Stefanos; El Azzouzi, Hamid; Salic, Kanita; Bourajjaj, Meriem; da Silva, Gustavo J J; Olieslagers, Servé; van der Nagel, Roel; de Weger, Roel; Bitsch, Nicole; Kisters, Natasja; Seyen, Sandrine; Morikawa, Yuka; Chanoine, Christophe; Heymans, Stephane; Volders, Paul G A; Thum, Thomas; Dimmeler, Stefanie; Cserjesi, Peter; Eschenhagen, Thomas; da Costa Martins, Paula A; De Windt, Leon J

    2013-11-01

    Although aberrant reactivation of embryonic gene programs is intricately linked to pathological heart disease, the transcription factors driving these gene programs remain ill-defined. Here we report that increased calcineurin/Nfat signalling and decreased miR-25 expression integrate to re-express the basic helix-loop-helix (bHLH) transcription factor dHAND (also known as Hand2) in the diseased human and mouse myocardium. In line, mutant mice overexpressing Hand2 in otherwise healthy heart muscle cells developed a phenotype of pathological hypertrophy. Conversely, conditional gene-targeted Hand2 mice demonstrated a marked resistance to pressure-overload-induced hypertrophy, fibrosis, ventricular dysfunction and induction of a fetal gene program. Furthermore, in vivo inhibition of miR-25 by a specific antagomir evoked spontaneous cardiac dysfunction and sensitized the murine myocardium to heart failure in a Hand2-dependent manner. Our results reveal that signalling cascades integrate with microRNAs to induce the expression of the bHLH transcription factor Hand2 in the postnatal mammalian myocardium with impact on embryonic gene programs in heart failure. PMID:24161931

  10. Olig2-dependent developmental fate switch of NG2 cells

    PubMed Central

    Zhu, Xiaoqin; Zuo, Hao; Maher, Brady J.; Serwanski, David R.; LoTurco, Joseph J.; Lu, Q. Richard; Nishiyama, Akiko

    2012-01-01

    NG2-expressing cells (NG2 cells or polydendrocytes) generate oligodendrocytes throughout the CNS and a subpopulation of protoplasmic astrocytes in the gray matter of the ventral forebrain. The mechanisms that regulate their oligodendrocyte or astrocyte fate and the degree to which they exhibit lineage plasticity in vivo have remained unclear. The basic helix-loop-helix transcription factor Olig2 is required for oligodendrocyte specification and differentiation. We have found that Olig2 expression is spontaneously downregulated in NG2 cells in the normal embryonic ventral forebrain as they differentiate into astrocytes. To further examine the role of Olig2 in NG2 cell fate determination, we used genetic fate mapping of NG2 cells in constitutive and tamoxifen-inducible Olig2 conditional knockout mice in which Olig2 was deleted specifically in NG2 cells. Constitutive deletion of Olig2 in NG2 cells in the neocortex and corpus callosum but not in ventral forebrain caused them to convert their fate into astrocytes, with a concomitant severe reduction in the number of oligodendrocytes and myelin. Deletion of Olig2 in NG2 cells in perinatal mice also resulted in astrocyte generation from neocortical NG2 cells. These observations indicate that the developmental fate of NG2 cells can be switched by altering a single transcription factor Olig2. PMID:22627280

  11. Olig2-dependent developmental fate switch of NG2 cells.

    PubMed

    Zhu, Xiaoqin; Zuo, Hao; Maher, Brady J; Serwanski, David R; LoTurco, Joseph J; Lu, Q Richard; Nishiyama, Akiko

    2012-07-01

    NG2-expressing cells (NG2 cells or polydendrocytes) generate oligodendrocytes throughout the CNS and a subpopulation of protoplasmic astrocytes in the gray matter of the ventral forebrain. The mechanisms that regulate their oligodendrocyte or astrocyte fate and the degree to which they exhibit lineage plasticity in vivo have remained unclear. The basic helix-loop-helix transcription factor Olig2 is required for oligodendrocyte specification and differentiation. We have found that Olig2 expression is spontaneously downregulated in NG2 cells in the normal embryonic ventral forebrain as they differentiate into astrocytes. To further examine the role of Olig2 in NG2 cell fate determination, we used genetic fate mapping of NG2 cells in constitutive and tamoxifen-inducible Olig2 conditional knockout mice in which Olig2 was deleted specifically in NG2 cells. Constitutive deletion of Olig2 in NG2 cells in the neocortex and corpus callosum but not in ventral forebrain caused them to convert their fate into astrocytes, with a concomitant severe reduction in the number of oligodendrocytes and myelin. Deletion of Olig2 in NG2 cells in perinatal mice also resulted in astrocyte generation from neocortical NG2 cells. These observations indicate that the developmental fate of NG2 cells can be switched by altering a single transcription factor Olig2. PMID:22627280

  12. Altered melanocyte differentiation and retinal pigmented epithelium transdifferentiation induced by Mash1 expression in pigment cell precursors.

    PubMed

    Lanning, Jessica L; Wallace, Jaclyn S; Zhang, Deming; Diwakar, Ganesh; Jiao, Zhongxian; Hornyak, Thomas J

    2005-10-01

    Transcription factor genes governing pigment cell development that are associated with spotting mutations in mice include members of several structural transcription factor classes but not members of the basic helix-loop-helix (bHLH) class, important for neurogenesis and myogenesis. To determine the effects of bHLH factor expression on pigment cell development, the neurogenic bHLH factor Mash1 was expressed early in pigment cell development in transgenic mice from the dopachrome tautomerase (Dct) promoter. Dct:Mash1 transgenic founders exhibit variable microphthalmia and patchy coat color hypopigmentation. Transgenic F1 mice exhibit microphthalmia with complete coat color dilution. Marker analysis demonstrates that Mash1 expression in the retinal pigmented epithelium (RPE) initiates neurogenesis in this cell layer, whereas expression in remaining neural crest-derived melanocytes alters their differentiation, in part by profoundly downregulating expression of the p (pink-eyed dilution) gene, while maintaining their cell fate. The effects of transcriptional perturbation of pigment cell precursors by Mash1 further highlight differences between pigment cells of distinct developmental origins, and suggest a mechanism for the alteration of melanogenesis to result in marked coat color dilution. PMID:16185282

  13. DAPT mediates atoh1 expression to induce hair cell-like cells

    PubMed Central

    Ren, Hongmiao; Guo, Weiwei; Liu, Wei; Gao, Weiqiang; Xie, Dinghua; Yin, Tuanfang; Yang, Shiming; Ren, Jihao

    2016-01-01

    Hearing loss is currently an incurable degenerative disease characterized by a paucity of hair cells (HCs), which cannot be spontaneously replaced in mammals. Recent technological advancements in gene therapy and local drug delivery have shed new light for hearing loss. Atoh1, also known as Math1, Hath1, and Cath1, is a proneural basic helix-loop-helix (bHLH) transcription factor that is essential for HC differentiation. At various stages in development, Atoh1 activity is sufficient to drive HC differentiation in the cochlea. Thus, Atoh1 related gene therapy is the most promising option for HC induction. DAPT, an inhibitor of Notch signaling, enhances the expression of Atoh1 indirectly, which in turn promotes the induction of a HC fate. Here, we show that DAPT cooperates with Atoh1 to synergistically promote HC fate in ependymal cells in vitro and promote hair cell regeneration in the cultured basilar membrane (BM) which mimics the microenvironment in vivo. Taken together, our findings demonstrated that DAPT is sufficient to induce HC-like cells via enhancing of the expression of Atoh1 to inhibit the progression of HC apoptosis and to induce new HC formation.

  14. Transcription factor Achaete-Scute homologue 2 initiates T follicular helper cell development

    PubMed Central

    Liu, Xindong; Chen, Xin; Zhong, Bo; Wang, Aibo; Wang, Xiaohu; Chu, Fuliang; Nurieva, Roza I.; Yan, Xiaowei; Chen, Ping; van der Flier, Laurens G.; Nakatsukasa, Hiroko; Neelapu, Sattva S; Chen, Wanjun; Clevers, Hans; Tian, Qiang; Qi, Hai; Wei, Lai; Dong, Chen

    2014-01-01

    In immune responses, activated T cells migrate to B cell follicles and develop to T follicular helper (Tfh) cells, a new subset of CD4+ T cells specialized in providing help to B lymphocytes in the induction of germinal centers 1,2. Although Bcl6 has been shown to be essential in Tfh cell function, it may not regulate the initial migration of T cells 3 or the induction of Tfh program as exampled by C-X-C chemokine receptor type 5 (CXCR5) upregulation 4. Here, we show that Achaete-Scute homologue 2 (Ascl2), a basic helix-loop-helix (bHLH) transcription factor 5, is selectively upregulated in its expression in Tfh cells. Ectopic expression of Ascl2 upregulates CXCR5 but not Bcl6 and downregulates C-C chemokine receptor 7 (CCR7) expression in T cells in vitro and accelerates T cell migration to the follicles and Tfh cell development in vivo. Genome-wide analysis indicates that Ascl2 directly regulates Tfh-related genes while inhibits expression of Th1 and Th17 genes. Acute deletion of Ascl2 as well as blockade of its function with the Id3 protein in CD4+ T cells results in impaired Tfh cell development and the germinal center response. Conversely, mutation of Id3, known to cause antibody-mediated autoimmunity, greatly enhances Tfh cell generation. Thus, Ascl2 directly initiates Tfh cell development. PMID:24463518

  15. Program Specificity for Ptf1a in Pancreas versus Neural Tube Development Correlates with Distinct Collaborating Cofactors and Chromatin Accessibility

    PubMed Central

    Meredith, David M.; Borromeo, Mark D.; Deering, Tye G.; Casey, Bradford H.; Savage, Trisha K.; Mayer, Paul R.; Hoang, Chinh; Tung, Kuang-Chi; Kumar, Manonmani; Shen, Chengcheng; Swift, Galvin H.

    2013-01-01

    The lineage-specific basic helix-loop-helix transcription factor Ptf1a is a critical driver for development of both the pancreas and nervous system. How one transcription factor controls diverse programs of gene expression is a fundamental question in developmental biology. To uncover molecular strategies for the program-specific functions of Ptf1a, we identified bound genomic regions in vivo during development of both tissues. Most regions bound by Ptf1a are specific to each tissue, lie near genes needed for proper formation of each tissue, and coincide with regions of open chromatin. The specificity of Ptf1a binding is encoded in the DNA surrounding the Ptf1a-bound sites, because these regions are sufficient to direct tissue-restricted reporter expression in transgenic mice. Fox and Sox factors were identified as potential lineage-specific modifiers of Ptf1a binding, since binding motifs for these factors are enriched in Ptf1a-bound regions in pancreas and neural tube, respectively. Of the Fox factors expressed during pancreatic development, Foxa2 plays a major role. Indeed, Ptf1a and Foxa2 colocalize in embryonic pancreatic chromatin and can act synergistically in cell transfection assays. Together, these findings indicate that lineage-specific chromatin landscapes likely constrain the DNA binding of Ptf1a, and they identify Fox and Sox gene families as part of this process. PMID:23754747

  16. Twist2 promotes kidney cancer cell proliferation and invasion by regulating ITGA6 and CD44 expression in the ECM-receptor interaction pathway

    PubMed Central

    Zhang, Hao-jie; Tao, Jing; Sheng, Lu; Hu, Xin; Rong, Rui-ming; Xu, Ming; Zhu, Tong-yu

    2016-01-01

    Twist2 is a member of the basic helix-loop-helix (bHLH) family and plays a critical role in tumorigenesis. Growing evidence has proven that Twist2 is involved in tumor progression; however, the role of Twist2 in human kidney cancer and its underlying mechanisms remain unclear. Real-time polymerase chain reaction and Western blot analysis were used to detect the expression of Twist2 in kidney cancer cells and tissues. Cell proliferation, cell cycle, apoptosis, migration, and invasion assay were analyzed using the Cell Count Kit-8, flow cytometry, wound healing, and Transwell analysis, respectively. In this study, we showed that Twist2 was upregulated in human kidney cancer tissues compared with normal kidney tissues. Twist2 promoted cell proliferation, inhibited cell apoptosis, and augmented cell migration and invasion in human kidney-cancer-derived cells in vitro. Twist2 also promoted tumor growth in vivo. Moreover, we found that the knockdown of Twist2 decreased the levels of ITGA6 and CD44 expression. This result indicates that Twist2 may promote migration and invasion of kidney cancer cells by regulating ITGA6 and CD44 expression. Therefore, our data demonstrated that Twist2 is involved in kidney cancer progression. The identification of the role of Twist2 in the migration and invasion of kidney cancer provides a potential appropriate treatment for human kidney cancer. PMID:27099513

  17. DEC1 and DEC2 Crosstalk between Circadian Rhythm and Tumor Progression

    PubMed Central

    Sato, Fuyuki; Bhawal, Ujjal K.; Yoshimura, Tomohiro; Muragaki, Yasuteru

    2016-01-01

    Clock genes, major regulators of circadian rhythm, are involved in tumor progression. We have shown that clock genes basic helix-loop-helix (BHLH) transcription factors, differentiated embryonic chondrocyte gene 1 (DEC1/BHLHE40/Sharp2/Stra13) and DEC2 (BHLHE41/Sharp1) play important roles in circadian rhythm, cell proliferation, apoptosis, hypoxia response, various stresses, and epithelial-to-mesenchymal transition (EMT) of tumor cells. Various stresses, such as exposure to transforming growth factor-beta (TGF-β), hypoxia, cytokines, serum-free, and anti-tumor drugs affect DEC1 and DEC2 expression. An increased or decreased expression of DEC1 and DEC2 regulated tumor progression. However, DEC1 and DEC2 have opposite effects in tumor progression, where the reason behind remains unclear. We found that DEC2 has circadian expression in implanted mouse sarcoma cells, suggesting that DEC2 regulates tumor progression under circadian rhythm. In addition to that, we showed that DEC1 and DEC2 regulate target genes via positive or negative feedback system in tumor progression. We propose that DEC1 and DEC2 act as an accelerator or a brake in tumor progression. In this review, we summarize current progress of knowledge in the function of DEC1 and DEC2 genes in tumor progression. PMID:26819638

  18. The Notch pathway inhibits TGF-β signaling in breast cancer through HEYL-mediated crosstalk

    PubMed Central

    Han, Liangfeng; Diehl, Adam; Nguyen, Nguyen; Korangath, Preethi; Teo, Weiwen; Cho, Soonweng; Kominsky, Scott; Huso, David L.; Feigenbaum, Lionel; Rein, Alan; Argani, Pedram; Landberg, Goran; Gessler, Manfred; Sukumar, Saraswati

    2014-01-01

    Acquired resistance to transforming growth factor-β (TGF-β) is a key step in the early stages of tumorigenesis. Mutations in TGF-β signaling components are rare, and little is known about development of resistance in breast cancer. On the other hand, an activated Notch pathway is known to play a substantial role in promoting breast cancer development. Here, we present evidence of crosstalk between these two pathways through HEYL. HEYL, a basic helix-loop-helix (bHLH) transcription factor and a direct target of Notch signaling, is specifically overexpressed in breast cancer. HEYL represses TGF-β activity by binding to TGF-β-activated Smads. HeyL−/− mice have defective mammary gland development with fewer terminal end buds. On the other hand, HeyL transgenic mice show accelerated mammary gland epithelial proliferation and 24% of multiparous mice develop mammary gland cancer. Therefore, repression of TGF-β signaling by Notch acting through HEYL may promote initiation of breast cancer. PMID:25217524

  19. Mesogenin 1 is a master regulator of paraxial presomitic mesoderm differentiation

    PubMed Central

    Chalamalasetty, Ravindra B.; Garriock, Robert J.; Dunty, William C.; Kennedy, Mark W.; Jailwala, Parthav; Si, Han; Yamaguchi, Terry P.

    2014-01-01

    Neuromesodermal (NM) stem cells generate neural and paraxial presomitic mesoderm (PSM) cells, which are the respective progenitors of the spinal cord and musculoskeleton of the trunk and tail. The Wnt-regulated basic helix-loop-helix (bHLH) transcription factor mesogenin 1 (Msgn1) has been implicated as a cooperative regulator working in concert with T-box genes to control PSM formation in zebrafish, although the mechanism is unknown. We show here that, in mice, Msgn1 alone controls PSM differentiation by directly activating the transcriptional programs that define PSM identity, epithelial-mesenchymal transition, motility and segmentation. Forced expression of Msgn1 in NM stem cells in vivo reduced the contribution of their progeny to the neural tube, and dramatically expanded the unsegmented mesenchymal PSM while blocking somitogenesis and notochord differentiation. Expression of Msgn1 was sufficient to partially rescue PSM differentiation in Wnt3a−/− embryos, demonstrating that Msgn1 functions downstream of Wnt3a as the master regulator of PSM differentiation. Our data provide new insights into how cell fate decisions are imposed by the expression of a single transcriptional regulator. PMID:25371364

  20. The Arabidopsis bHLH Transcription Factors MYC3 and MYC4 Are Targets of JAZ Repressors and Act Additively with MYC2 in the Activation of Jasmonate Responses[C][W

    PubMed Central

    Fernández-Calvo, Patricia; Chini, Andrea; Fernández-Barbero, Gemma; Chico, José-Manuel; Gimenez-Ibanez, Selena; Geerinck, Jan; Eeckhout, Dominique; Schweizer, Fabian; Godoy, Marta; Franco-Zorrilla, José Manuel; Pauwels, Laurens; Witters, Erwin; Puga, María Isabel; Paz-Ares, Javier; Goossens, Alain; Reymond, Philippe; De Jaeger, Geert; Solano, Roberto

    2011-01-01

    Jasmonates (JAs) trigger an important transcriptional reprogramming of plant cells to modulate both basal development and stress responses. In spite of the importance of transcriptional regulation, only one transcription factor (TF), the Arabidopsis thaliana basic helix-loop-helix MYC2, has been described so far as a direct target of JAZ repressors. By means of yeast two-hybrid screening and tandem affinity purification strategies, we identified two previously unknown targets of JAZ repressors, the TFs MYC3 and MYC4, phylogenetically closely related to MYC2. We show that MYC3 and MYC4 interact in vitro and in vivo with JAZ repressors and also form homo- and heterodimers with MYC2 and among themselves. They both are nuclear proteins that bind DNA with sequence specificity similar to that of MYC2. Loss-of-function mutations in any of these two TFs impair full responsiveness to JA and enhance the JA insensitivity of myc2 mutants. Moreover, the triple mutant myc2 myc3 myc4 is as impaired as coi1-1 in the activation of several, but not all, JA-mediated responses such as the defense against bacterial pathogens and insect herbivory. Our results show that MYC3 and MYC4 are activators of JA-regulated programs that act additively with MYC2 to regulate specifically different subsets of the JA-dependent transcriptional response. PMID:21335373

  1. CD26-mediated regulation of periostin expression contributes to migration and invasion of malignant pleural mesothelioma cells

    SciTech Connect

    Komiya, Eriko; Ohnuma, Kei; Yamazaki, Hiroto; Hatano, Ryo; Iwata, Satoshi; Okamoto, Toshihiro; Dang, Nam H.; Morimoto, Chikao

    2014-05-16

    Highlights: • CD26-expressing MPM cells upregulate production of periostin. • The intracytoplasmic region of CD26 mediates the upregulation of periostin. • CD26 expression leads to nuclear translocation of Twist1 via phosphorylation of Src. • Secreted periostin enhances migration and invasion of MPM cells. - Abstract: Malignant pleural mesothelioma (MPM) is an aggressive malignancy arising from mesothelial lining of pleura. It is generally associated with a history of asbestos exposure and has a very poor prognosis, partly due to the lack of a precise understanding of the molecular mechanisms associated with its malignant behavior. In the present study, we expanded on our previous studies on the enhanced motility and increased CD26 expression in MPM cells, with a particular focus on integrin adhesion molecules. We found that expression of CD26 upregulates periostin secretion by MPM cells, leading to enhanced MPM cell migratory and invasive activity. Moreover, we showed that upregulation of periostin expression results from the nuclear translocation of the basic helix-loop-helix transcription factor Twist1, a process that is mediated by CD26-associated activation of Src phosphorylation. While providing new and profound insights into the molecular mechanisms involved in MPM biology, these findings may also lead to the development of novel therapeutic strategies for MPM.

  2. The Transcription Factor Hand1 Is Involved In Runx2-Ihh-Regulated Endochondral Ossification

    PubMed Central

    Laurie, Lindsay E.; Kokubo, Hiroki; Nakamura, Masataka; Saga, Yumiko; Funato, Noriko

    2016-01-01

    The developing long bone is a model of endochondral ossification that displays the morphological layers of chondrocytes toward the ossification center of the diaphysis. Indian hedgehog (Ihh), a member of the hedgehog family of secreted molecules, regulates chondrocyte proliferation and differentiation, as well as osteoblast differentiation, through the process of endochondral ossification. Here, we report that the basic helix-loop-helix transcription factor Hand1, which is expressed in the cartilage primordia, is involved in proper osteogenesis of the bone collar via its control of Ihh production. Genetic overexpression of Hand1 in the osteochondral progenitors resulted in prenatal hypoplastic or aplastic ossification in the diaphyses, mimicking an Ihh loss-of-function phenotype. Ihh expression was downregulated in femur epiphyses of Hand1-overexpressing mice. We also confirmed that Hand1 downregulated Ihh gene expression in vitro by inhibiting Runx2 transactivation of the Ihh proximal promoter. These results demonstrate that Hand1 in chondrocytes regulates endochondral ossification, at least in part through the Runx2-Ihh axis. PMID:26918743

  3. Ascl1-induced neuronal differentiation of P19 cells requires expression of a specific inhibitor protein of cAMP-dependent protein kinase

    PubMed Central

    Huang, Holly S.; Turner, David L.; Thompson, Robert C.; Uhler, Michael D.

    2011-01-01

    cAMP-dependent protein kinase (PKA) plays a critical role in nervous system development by modulating sonic hedgehog and bone morphogenetic protein signaling. In the current studies, P19 embryonic carcinoma cells were neuronally differentiated by expression of the proneural basic helix-loop-helix transcription factor Ascl1. After expression of Ascl1, but prior to expression of neuronal markers such as microtubule associated protein 2 and neuronal β-tubulin, P19 cells demonstrated a large, transient increase in both mRNA and protein for the endogenous protein kinase inhibitor (PKI)β. PKIβ-targeted shRNA constructs both reduced the levels of PKIβ expression and blocked the neuronal differentiation of P19 cells. This inhibition of differentiation was rescued by transfection of a shRNA-resistant expression vector for the PKIβ protein, and this rescue required the PKA-specific inhibitory sequence of the PKIβprotein. PKIβ played a very specific role in the Ascl1-mediated differentiation process since other PKI isoforms were unable to rescue the deficit conferred by shRNA-mediated knockdown of PKIβ. Our results define a novel requirement for PKIβ and its inhibition of PKA during neuronal differentiation of P19 cells. PMID:21623794

  4. Synthetic lethal analysis of Caenorhabditis elegans posterior embryonic patterning genes identifies conserved genetic interactions

    PubMed Central

    Baugh, L Ryan; Wen, Joanne C; Hill, Andrew A; Slonim, Donna K; Brown, Eugene L; Hunter, Craig P

    2005-01-01

    Phenotypic robustness is evidenced when single-gene mutations do not result in an obvious phenotype. It has been suggested that such phenotypic stability results from 'buffering' activities of homologous genes as well as non-homologous genes acting in parallel pathways. One approach to characterizing mechanisms of phenotypic robustness is to identify genetic interactions, specifically, double mutants where buffering is compromised. To identify interactions among genes implicated in posterior patterning of the Caenorhabditis elegans embryo, we measured synthetic lethality following RNA interference of 22 genes in 15 mutant strains. A pair of homologous T-box transcription factors (tbx-8 and tbx-9) is found to interact in both C. elegans and C. briggsae, indicating that their compensatory function is conserved. Furthermore, a muscle module is defined by transitive interactions between the MyoD homolog hlh-1, another basic helix-loop-helix transcription factor, hnd-1, and the MADS-box transcription factor unc-120. Genetic interactions within a homologous set of genes involved in vertebrate myogenesis indicate broad conservation of the muscle module and suggest that other genetic modules identified in C. elegans will be conserved. PMID:15892873

  5. Virulence Factors of Geminivirus Interact with MYC2 to Subvert Plant Resistance and Promote Vector Performance[C][W

    PubMed Central

    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

    2014-01-01

    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 βC1 of Tomato yellow leaf curl China virus, a monopartite begomovirus, as the viral genetic factor that suppresses plant terpene biosynthesis. βC1 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

  6. Cloning and characterization of DELLA genes in Artemisia annua.

    PubMed

    Shen, Q; Cui, J; Fu, X Q; Yan, T X; Tang, K X

    2015-01-01

    Gibberellins (GA) are some of the most important phytohormones involved in plant development. DELLA proteins are negative regulators of GA signaling in many plants. In this study, the full-length cDNA sequences of three DELLA genes were cloned from Artemisia annua. Phylogenetic analysis revealed that AaDELLA1 and AaDELLA2 were located in the same cluster, but AaDELLA3 was not. Subcellular localization analysis suggested that AaDELLAs can be targeted to the nucleus and/or cytoplasm. Real-time PCR indicated that all three AaDELLA genes exhibited the highest expression in seeds. Expression of all AaDELLA genes was enhanced by exogenous MeJA treatment but inhibited by GA3 treatment. Yeast two-hybrid assay showed that AaDELLAs could interact with basic helix-loop-helix transcription factor AaMYC2, suggesting that GA and JA signaling may be involved in cross-talk via DELLA and MYC2 interaction in A. annua. PMID:26345940

  7. Ectopic Atoh1 expression drives Merkel cell production in embryonic, postnatal and adult mouse epidermis.

    PubMed

    Ostrowski, Stephen M; Wright, Margaret C; Bolock, Alexa M; Geng, Xuehui; Maricich, Stephen M

    2015-07-15

    Merkel cells are mechanosensitive skin cells whose production requires the basic helix-loop-helix transcription factor Atoh1. We induced ectopic Atoh1 expression in the skin of transgenic mice to determine whether Atoh1 was sufficient to create additional Merkel cells. In embryos, ectopic Atoh1 expression drove ectopic expression of the Merkel cell marker keratin 8 (K8) throughout the epidermis. Epidermal Atoh1 induction in adolescent mice similarly drove widespread K8 expression in glabrous skin of the paws, but in the whisker pads and body skin ectopic K8+ cells were confined to hair follicles and absent from interfollicular regions. Ectopic K8+ cells acquired several characteristics of mature Merkel cells in a time frame similar to that seen during postnatal development of normal Merkel cells. Although ectopic K8+ cell numbers decreased over time, small numbers of these cells remained in deep regions of body skin hair follicles at 3 months post-induction. In adult mice, greater numbers of ectopic K8+ cells were created by Atoh1 induction during anagen versus telogen and following disruption of Notch signaling by conditional deletion of Rbpj in the epidermis. Our data demonstrate that Atoh1 expression is sufficient to produce new Merkel cells in the epidermis, that epidermal cell competency to respond to Atoh1 varies by skin location, developmental age and hair cycle stage, and that the Notch pathway plays a key role in limiting epidermal cell competency to respond to Atoh1 expression. PMID:26138479

  8. A switch from Myc:Max to Mad:Max heterocomplexes accompanies monocyte/macrophage differentiation.

    TOXLINE Toxicology Bibliographic Information

    Ayer DE; Eisenman RN

    1993-11-01

    Mad is a basic-helix-loop-helix-zipper protein that heterodimerizes with Max in vitro. Mad:Max heterodimers recognize the same E-box-related DNA-binding sites as Myc:Max heterodimers. However, in transient transfection assays Myc and Mad influence transcription in opposite ways through interaction with Max; Myc activates while Mad represses transcription. Here, we demonstrate that Mad protein is induced rapidly upon differentiation of cells of the myeloid lineage. The Mad protein is synthesized in human cells as a 35-kD nuclear phosphoprotein with an extremely short half-life (t1/2 = 15-30 min) and can be detected in vivo in a complex with Max. In the undifferentiated U937 monocyte cell line Max was found complexed with Myc but not Mad. However, Mad:Max complexes began to accumulate as early as 2 hr after induction of macrophage differentiation with TPA. By 48 hr following TPA treatment only Mad:Max complexes were detectable. These data show that differentiation is accompanied by a change in the composition of Max heterocomplexes. We speculate that this switch in heterocomplexes results in a change in the transcriptional regulation of Myc:Max target genes required for cell proliferation.

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

    SciTech Connect

    Yamaki, Akiko; Kudoh, Jun; Shindoh, Nobuaki

    1996-07-01

    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.

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

    PubMed Central

    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

    2014-01-01

    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/β-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

  11. Generation of induced neurons by direct reprogramming in the mammalian cochlea.

    PubMed

    Nishimura, K; Weichert, R M; Liu, W; Davis, R L; Dabdoub, A

    2014-09-01

    Primary auditory neurons (ANs) in the mammalian cochlea play a critical role in hearing as they transmit auditory information in the form of electrical signals from mechanosensory cochlear hair cells in the inner ear to the brainstem. Their progressive degeneration is associated with disease conditions, excessive noise exposure and aging. Replacement of ANs, which lack the ability to regenerate spontaneously, would have a significant impact on research and advancement in cochlear implants in addition to the amelioration of hearing impairment. The aim of this study was to induce a neuronal phenotype in endogenous non-neural cells in the cochlea, which is the essential organ of hearing. Overexpression of a neurogenic basic helix-loop-helix transcription factor, Ascl1, in the cochlear non-sensory epithelial cells induced neurons at high efficiency at embryonic, postnatal and juvenile stages. Moreover, induced neurons showed typical properties of neuron morphology, gene expression and electrophysiology. Our data indicate that Ascl1 alone or Ascl1 and NeuroD1 is sufficient to reprogram cochlear non-sensory epithelial cells into functional neurons. Generation of neurons from non-neural cells in the cochlea is an important step for the regeneration of ANs in the mature mammalian cochlea. PMID:24928351

  12. Slow transition between two beta-strand registers is dictated by protein unfolding.

    PubMed

    Evans, Matthew R; Gardner, Kevin H

    2009-08-19

    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 Ibeta-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 time scale 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 nondenaturing conditions. Taken together, these data provide information about a rare equilibrium model system for beta-strand slippage. PMID:19722642

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

    PubMed

    Fritzsch, Bernd

    2003-06-15

    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

  14. An RNA Virus-Encoded Zinc-Finger Protein Acts as a Plant Transcription Factor and Induces a Regulator of Cell Size and Proliferation in Two Tobacco Species[C][W

    PubMed Central

    Lukhovitskaya, Nina I.; Solovieva, Anna D.; Boddeti, Santosh K.; Thaduri, Srinivas; Solovyev, Andrey G.; Savenkov, Eugene I.

    2013-01-01

    Plant viruses cause a variety of diseases in susceptible hosts. The disease symptoms often include leaf malformations and other developmental abnormalities, suggesting that viruses can affect plant development. However, little is known about the mechanisms underlying virus interference with plant morphogenesis. Here, we show that a C-4 type zinc-finger (ZF) protein, p12, encoded by a carlavirus (chrysanthemum virus B) can induce cell proliferation, which results in hyperplasia and severe leaf malformation. We demonstrate that the p12 protein activates expression of a regulator of cell size and proliferation, designated upp-L (upregulated by p12), which encodes a transcription factor of the basic/helix-loop-helix family sufficient to cause hyperplasia. The induction of upp-L requires translocation of the p12 protein into the nucleus and ZF-dependent specific interaction with the conserved regulatory region in the upp-L promoter. Our results establish the role of the p12 protein in modulation of host cell morphogenesis. It is likely that other members of the conserved C-4 type ZF family of viral proteins instigate reprogramming of plant development by mimicking eukaryotic transcriptional activators. PMID:23482855

  15. RSL Class I Genes Controlled the Development of Epidermal Structures in the Common Ancestor of Land Plants

    PubMed Central

    Proust, Hélène; Honkanen, Suvi; Jones, Victor A.S.; Morieri, Giulia; Prescott, Helen; Kelly, Steve; Ishizaki, Kimitsune; Kohchi, Takayuki; Dolan, Liam

    2016-01-01

    Summary The colonization of the land by plants, sometime before 470 million years ago, was accompanied by the evolution tissue systems [1, 2, 3]. Specialized structures with diverse functions—from nutrient acquisition to reproduction—derived from single cells in the outermost layer (epidermis) were important sources of morphological innovation at this time [2, 4, 5]. In extant plants, these structures may be unicellular extensions, such as root hairs or rhizoids [6, 7, 8, 9], or multicellular structures, such as asexual propagules or secretory hairs (papillae) [10, 11, 12]. Here, we show that a ROOTHAIR DEFECTIVE SIX-LIKE (RSL) class I basic helix-loop-helix transcription factor positively regulates the development of the unicellular and multicellular structures that develop from individual cells that expand out of the epidermal plane of the liverwort Marchantia polymorpha; mutants that lack MpRSL1 function do not develop rhizoids, slime papillae, mucilage papillae, or gemmae. Furthermore, we discovered that RSL class I genes are also required for the development of multicellular axillary hairs on the gametophyte of the moss Physcomitrella patens. Because class I RSL proteins also control the development of rhizoids in mosses and root hairs in angiosperms [13, 14], these data demonstrate that the function of RSL class I genes was to control the development of structures derived from single epidermal cells in the common ancestor of the land plants. Class I RSL genes therefore controlled the generation of adaptive morphological diversity as plants colonized the land from the water. PMID:26725198

  16. Dual-mode modulation of Smad signaling by Smad-interacting protein Sip1 is required for myelination in the central nervous system.

    PubMed

    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

    2012-02-23

    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/β-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 β-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

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

    PubMed Central

    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

    2012-01-01

    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/β-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 β-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

  18. The plant-specific protein FEHLSTART controls male meiotic entry, initializing meiotic synchronization in Arabidopsis.

    PubMed

    Li, Junhua; Dukowic-Schulze, Stefanie; Lindquist, Ingrid E; Farmer, Andrew D; Kelly, Bridget; Li, Tao; Smith, Alan G; Retzel, Ernest F; Mudge, Joann; Chen, Changbin

    2015-11-01

    Meiosis marks the transition from the sporophyte to the gametophyte generation in the life cycle of flowering plants, and creates genetic variations through homologous recombination. In most flowering plants, meiosis is highly synchronized within each anther, which is significant for efficient fertilization. To date, little is known about the molecular mechanisms of entry into meiosis and exit from it, and only a few genes in Arabidopsis have been characterized with a role in regulating meiotic progression. In this study, we report the functional characterization of a plant-specific basic helix-loop-helix (bHLH) protein, FEHLSTART (FST), a defect in which leads to premature meiotic entry and asynchronous meiosis, and results in decreased seed yield. Investigation of the time course of meiosis showed that the onset of leptotene, the first stage of prophase I, frequently occurred earlier in fst-1 than in the wild type. Asynchronous meiosis followed, which could manifest in the disruption of regular spindle structures and symmetric cell divisions in fst-1 mutants during the meiosis I/II transition. In accordance with frequently accelerated meiotic entry, whole-transcriptome analysis of fst-1 anthers undergoing meiosis revealed that 19 circadian rhythm genes were affected and 47 pollen-related genes were prematurely expressed at a higher level. Taken together, we propose that FST is required for normal meiotic entry and the establishment of meiotic synchrony. PMID:26382719

  19. Impaired glucocorticoid production and response to stress in Arntl-deficient male mice.

    PubMed

    Leliavski, Alexei; Shostak, Anton; Husse, Jana; Oster, Henrik

    2014-01-01

    The basic helix-loop-helix transcription factor Aryl Hydrocarbon Receptor Nuclear Translocator-Like (ARNTL, also known as BMAL1 or MOP3) is a core component of the circadian timing system in mammals, which orchestrates 24-hour rhythms of physiology and behavior. Genetic ablation of Arntl in mice leads to behavioral and physiological arrhythmicity, including loss of circadian baseline regulation of glucocorticoids (GCs). GCs are important downstream regulators of circadian tissue clocks and have essential functions in the physiological adaptation to stress. The role of the clock machinery in the regulation of stress-induced GC release, however, is not well understood. Here we show that already under unstressed conditions Arntl-deficient mice suffer from hypocortisolism with impaired adrenal responsiveness to ACTH and down-regulated transcription of genes involved in cholesterol transport in adrenocortical cells. Under stress they show diminished GC and behavioral responses and develop behavioral resistance to acute and subchronic stressors, as shown using forced swim, tail suspension, and sucrose preference tests. These data suggest that the clock gene Arntl regulates circadian and acute secretion of GCs by the adrenal gland. Arntl disruption, probably via its effect on adrenal clock function, modulates stress axis activity and, thus, may promote resistance to both acute and repeated stress. PMID:24189141

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

    PubMed

    Richardson, Lynn G L; Torii, Keiko U

    2013-12-01

    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

  1. Organ-specific effects of brassinosteroids on stomatal production coordinate with the action of Too Many Mouths.

    PubMed

    Wang, Ming; Yang, Kezhen; Le, Jie

    2015-03-01

    In Arabidopsis, stomatal development initiates after protodermal cells acquire stomatal lineage cell fate. Stomata or their precursors communicate with their neighbor epidermal cells to ensure the "one cell spacing" rule. The signals from EPF/EPFL peptide ligands received by Too Many Mouths (TMM) and ERECTA-family receptors are supposed to be transduced by YODA MAPK cascade. A basic helix-loop-helix transcription factor SPEECHLESS (SPCH) is another key regulator of stomatal cell fate determination and asymmetric entry divisions, and SPCH activity is regulated by YODA MAPK cascade. Brassinosteroid (BR) signaling, one of the most well characterized signal transduction pathways in plants, contributes to the control of stomatal production. But opposite organ-specific effects of BR on stomatal production were reported. Here we confirm that stomatal production in hypocotyls is controlled by BR levels. YODA and CYCD4 are not essential for BR stomata-promoting function. Furthermore, we found that BR could confer tmm hypocotyls clustered stomatal phenotype, indicating that the BR organ-specific effects on stomatal production might coordinate with the TMM organ-specific actions. PMID:25234048

  2. Origins of enhancer sequences of recombinant murine leukemia viruses from spontaneous B- and T-cell lymphomas of CWD mice.

    PubMed

    Massey, A C; Lawrenz-Smith, S C; Innes, D J; Thomas, C Y

    1994-06-01

    Recombinant murine leukemia viruses from the highly leukemic mouse strains AKR, HRS, and C58 usually acquire pathogenic U3 region sequences fro the endogenous xenotropic virus, Bxv-1. However, the majority of tumors from another highly leukemic strain, CWD, contained recombinant viruses that lacked Bxv-1-specific sequences. The nucleotide sequence of the U3 regions of two such CWD recombinants was nearly identical to that of the endogenous ecotropic virus parent Emv-1, but they shared three nucleotide substitutions immediately 3' of the enhancer core. These substitutions were found in recombinant proviruses from about one-third of spontaneous CWD lymphomas as determined by an oligonucleotide hybridization assay of proviral fragments that had been nucleotide substitutions in the CWD viruses were inherited from an endogenous polytropic provirus that is absent in the other highly leukemic strains. On the basis of the results of these and previous studies, we propose that CWD recombinants acquire pathogenic U3 region sequences through recombination with an endogenous polytropic virus or Bxv-1 and that the pathogenicity of these sequences may be related to a sequence motif that is known to bind members of the basic helix-loop-helix class of transcription factors. PMID:8189515

  3. Antagonistic HLH/bHLH Transcription Factors Mediate Brassinosteroid Regulation of Cell Elongation and Plant Development in Rice and Arabidopsis[C][W][OA

    PubMed Central

    Zhang, Li-Ying; Bai, Ming-Yi; Wu, Jinxia; Zhu, Jia-Ying; Wang, Hao; Zhang, Zhiguo; Wang, Wenfei; Sun, Yu; Zhao, Jun; Sun, Xuehui; Yang, Hongjuan; Xu, Yunyuan; Kim, Soo-Hwan; Fujioka, Shozo; Lin, Wen-Hui; Chong, Kang; Lu, Tiegang; Wang, Zhi-Yong

    2009-01-01

    In rice (Oryza sativa), brassinosteroids (BRs) induce cell elongation at the adaxial side of the lamina joint to promote leaf bending. We identified a rice mutant (ili1-D) showing an increased lamina inclination phenotype similar to that caused by BR treatment. The ili1-D mutant overexpresses an HLH protein homologous to Arabidopsis thaliana Paclobutrazol Resistance1 (PRE1) and the human Inhibitor of DNA binding proteins. Overexpression and RNA interference suppression of ILI1 increase and reduce, respectively, rice laminar inclination, confirming a positive role of ILI1 in leaf bending. ILI1 and PRE1 interact with basic helix-loop-helix (bHLH) protein IBH1 (ILI1 binding bHLH), whose overexpression causes erect leaf in rice and dwarfism in Arabidopsis. Overexpression of ILI1 or PRE1 increases cell elongation and suppresses dwarf phenotypes caused by overexpression of IBH1 in Arabidopsis. Thus, ILI1 and PRE1 may inactivate inhibitory bHLH transcription factors through heterodimerization. BR increases the RNA levels of ILI1 and PRE1 but represses IBH1 through the transcription factor BZR1. The spatial and temporal expression patterns support roles of ILI1 in laminar joint bending and PRE1/At IBH1 in the transition from growth of young organs to growth arrest. These results demonstrate a conserved mechanism of BR regulation of plant development through a pair of antagonizing HLH/bHLH transcription factors that act downstream of BZR1 in Arabidopsis and rice. PMID:20009022

  4. Induction of insulin and islet amyloid polypeptide production in pancreatic islet glucagonoma cells by insulin promoter factor 1.

    PubMed Central

    Serup, P; Jensen, J; Andersen, F G; Jørgensen, M C; Blume, N; Holst, J J; Madsen, O D

    1996-01-01

    Insulin promoter factor 1 (IPF1), a member of the homeodomain protein family, serves an early role in pancreas formation, as evidenced by the lack of pancreas formation in mice carrying a targeted disruption of the IPF1 gene [Jonsson, J., Carlsson, L., Edlund, T. & Edlund, H. (1994) Nature (London) 371, 606-609]. In adults, IPF1 expression is restricted to the beta-cells in the islets of Langerhans. We report here that IPF1 induces expression of a subset of beta-cell-specific genes (insulin and islet amyloid polypeptide) when ectopically expressed in clones of transformed pancreatic islet alpha-cells. In contrast, expression of IPF1 in rat embryo fibroblasts factor failed to induce insulin and islet amyloid polypeptide expression. This is most likely due to the lack of at least one other essential insulin gene transcription factor, the basic helix-loop-helix protein Beta 2/NeuroD, which is expressed in both alpha- and beta-cells. We conclude that IPF1 is a potent transcriptional activator of endogenous insulin genes in non-beta islet cells, which suggests an important role of IPF1 in beta-cell maturation. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8799146

  5. Regulation of the Mechanism of TWIST1 Transcription by BHLHE40 and BHLHE41 in Cancer Cells.

    PubMed

    Asanoma, Kazuo; Liu, Ge; Yamane, Takako; Miyanari, Yoko; Takao, Tomoka; Yagi, Hiroshi; Ohgami, Tatsuhiro; Ichinoe, Akimasa; Sonoda, Kenzo; Wake, Norio; Kato, Kiyoko

    2015-12-01

    BHLHE40 and BHLHE41 (BHLHE40/41) are basic helix-loop-helix type transcription factors that play key roles in multiple cell behaviors. BHLHE40/41 were recently shown to be involved in an epithelial-to-mesenchymal transition (EMT). However, the precise mechanism of EMT control by BHLHE40/41 remains unclear. In the present study, we demonstrated that BHLHE40/41 expression was controlled in a pathological stage-dependent manner in human endometrial cancer (HEC). Our in vitro assays showed that BHLHE40/41 suppressed tumor cell invasion. BHLHE40/41 also suppressed the transcription of the EMT effectors SNAI1, SNAI2, and TWIST1. We identified the critical promoter regions of TWIST1 for its basal transcriptional activity. We elucidated that the transcription factor SP1 was involved in the basal transcriptional activity of TWIST1 and that BHLHE40/41 competed with SP1 for DNA binding to regulate gene transcription. This study is the first to report the detailed functions of BHLHE40 and BHLHE41 in the suppression of EMT effectors in vitro. Our results suggest that BHLHE40/41 suppress tumor cell invasion by inhibiting EMT in tumor cells. We propose that BHLHE40/41 are promising markers to predict the aggressiveness of each HEC case and that molecular targeting strategies involving BHLHE40/41 and SP1 may effectively regulate HEC progression. PMID:26391953

  6. Mox2 is a component of the genetic hierarchy controlling limb muscle development.

    PubMed

    Mankoo, B S; Collins, N S; Ashby, P; Grigorieva, E; Pevny, L H; Candia, A; Wright, C V; Rigby, P W; Pachnis, V

    1999-07-01

    The skeletal muscles of the limbs develop from myogenic progenitors that originate in the paraxial mesoderm and migrate into the limb-bud mesenchyme. Among the genes known to be important for muscle development in mammalian embryos are those encoding the basic helix-loop-helix (bHLH) myogenic regulatory factors (MRFs; MyoD, Myf5, myogenin and MRF4) and Pax3, a paired-type homeobox gene that is critical for the development of limb musculature. Mox1 and Mox2 are closely related homeobox genes that are expressed in overlapping patterns in the paraxial mesoderm and its derivatives. Here we show that mice homozygous for a null mutation of Mox2 have a developmental defect of the limb musculature, characterized by an overall reduction in muscle mass and elimination of specific muscles. Mox2 is not needed for the migration of myogenic precursors into the limb bud, but it is essential for normal appendicular muscle formation and for the normal regulation of myogenic genes, as demonstrated by the downregulation of Pax3 and Myf5 but not MyoD in Mox2-deficient limb buds. Our findings show that the MOX2 homeoprotein is an important regulator of vertebrate limb myogenesis. PMID:10403250

  7. Identification of soybean MYC2-like transcription factors and overexpression of GmMYC1 could stimulate defense mechanism against common cutworm in transgenic tobacco.

    PubMed

    Wang, Hui; Ding, Changwen; Du, Haiping; Liu, Hailun; Wang, Yongli; Yu, Deyue

    2014-09-01

    MYC2 is a basic helix-loop-helix Leu zipper transcription factor (TF). Here, 22 putative soybean MYC-like TFs were identified bioinformatically. Of these TFs, seven MYC2-like genes without introns were isolated and characterized. All seven GmMYCs displayed transactivation activity in yeast cells. Six genes (excepting GmMYC3) were expressed in the roots, stems, leaves, flowers, and seed wall but not in the developing seeds and up-regulated after insect feeding. The GmMYC1 transgenic tobacco rejected common cutworm (CCW, Spodoptera litura Fabricius) more strongly and lost less leaf area than the control (2.94 ± 2.36 vs 7.84 ± 4.63 cm(2)). The average relative growth rate of CCW feeding on transgenic tobacco leaves was lower than on control tobacco leaves (136 ± 60 vs 271 ± 76 %). These results indicated that GmMYC could stimulate the defense mechanism against insects in plants. PMID:24863293

  8. EsxB, a secreted protein from Bacillus anthracis forms two distinct helical bundles

    DOE PAGESBeta

    Fan, Yao; Tan, Kemin; Chhor, Gekleng; Butler, Emily K.; Jedrzejczak, Robert P.; Missiakas, Dominique; Joachimiak, Andrzej

    2015-07-03

    The EsxB protein from Bacillus anthracis belongs to the WXG100 family, a group of proteins secreted by a specialized secretion system. We have determined the crystal structures of recombinant EsxB and discovered that the small protein (~10 kDa), comprised of a helix-loop-helix (HLH) hairpin, is capable of associating into two different helical bundles. The two basic quaternary assemblies of EsxB are an antiparallel (AP) dimer and a rarely observed bisecting U (BU) dimer. This structural duality of EsxB is believed to originate from the heptad repeat sequence diversity of the first helix of its HLH hairpin, which allows for twomore » alternative helix packing. The flexibility of EsxB and the ability to form alternative helical bundles underscore the possibility that this protein can serve as an adaptor in secretion and can form hetero-oligomeric helix bundle(s) with other secreted members of the WXG100 family, such as EsxW. The highly conserved WXG motif is located within the loop of the HLH hairpin and is mostly buried within the helix bundle suggesting that its role is mainly structural. The exact functions of the motif, including a proposed role as a secretion signal, remain unknown.« less

  9. EsxB, a secreted protein from Bacillus anthracis forms two distinct helical bundles

    SciTech Connect

    Fan, Yao; Tan, Kemin; Chhor, Gekleng; Butler, Emily K.; Jedrzejczak, Robert P.; Missiakas, Dominique; Joachimiak, Andrzej

    2015-07-03

    The EsxB protein from Bacillus anthracis belongs to the WXG100 family, a group of proteins secreted by a specialized secretion system. We have determined the crystal structures of recombinant EsxB and discovered that the small protein (~10 kDa), comprised of a helix-loop-helix (HLH) hairpin, is capable of associating into two different helical bundles. The two basic quaternary assemblies of EsxB are an antiparallel (AP) dimer and a rarely observed bisecting U (BU) dimer. This structural duality of EsxB is believed to originate from the heptad repeat sequence diversity of the first helix of its HLH hairpin, which allows for two alternative helix packing. The flexibility of EsxB and the ability to form alternative helical bundles underscore the possibility that this protein can serve as an adaptor in secretion and can form hetero-oligomeric helix bundle(s) with other secreted members of the WXG100 family, such as EsxW. The highly conserved WXG motif is located within the loop of the HLH hairpin and is mostly buried within the helix bundle suggesting that its role is mainly structural. The exact functions of the motif, including a proposed role as a secretion signal, remain unknown.

  10. The Birth of a Black Rice Gene and Its Local Spread by Introgression.

    PubMed

    Oikawa, Tetsuo; Maeda, Hiroaki; Oguchi, Taichi; Yamaguchi, Takuya; Tanabe, Noriko; Ebana, Kaworu; Yano, Masahiro; Ebitani, Takeshi; Izawa, Takeshi

    2015-09-01

    The origin and spread of novel agronomic traits during crop domestication are complex events in plant evolution. Wild rice (Oryza rufipogon) has red grains due to the accumulation of proanthocyanidins, whereas most cultivated rice (Oryza sativa) varieties have white grains induced by a defective allele in the Rc basic helix-loop-helix (bHLH) gene. Although the events surrounding the origin and spread of black rice traits remain unknown, varieties with black grains due to anthocyanin accumulation are distributed in various locations throughout Asia. Here, we show that the black grain trait originated from ectopic expression of the Kala4 bHLH gene due to rearrangement in the promoter region. Both the Rc and Kala4 genes activate upstream flavonol biosynthesis genes, such as chalcone synthase and dihydroflavonol-4-reductase, and downstream genes, such as leucoanthocyanidin reductase and leucoanthocyanidin dioxygenase, to produce the respective specific pigments. Genome analysis of 21 black rice varieties as well as red- and white-grained landraces demonstrated that black rice arose in tropical japonica and its subsequent spread to the indica subspecies can be attributed to the causal alleles of Kala4. The relatively small size of genomic fragments of tropical japonica origin in some indica varieties indicates that refined introgression must have occurred by natural crossbreeding in the course of evolution of the black trait in rice. PMID:26362607

  11. Inhibitory PAS domain protein is a negative regulator of hypoxia-inducible gene expression

    NASA Astrophysics Data System (ADS)

    Makino, Yuichi; Cao, Renhai; Svensson, Kristian; Bertilsson, Göran; Asman, Mikael; Tanaka, Hirotoshi; Cao, Yihai; Berkenstam, Anders; Poellinger, Lorenz

    2001-11-01

    Alteration of gene expression is a crucial component of adaptive responses to hypoxia. These responses are mediated by hypoxia-inducible transcription factors (HIFs). Here we describe an inhibitory PAS (Per/Arnt/Sim) domain protein, IPAS, which is a basic helix-loop-helix (bHLH)/PAS protein structurally related to HIFs. IPAS contains no endogenous transactivation function but demonstrates dominant negative regulation of HIF-mediated control of gene expression. Ectopic expression of IPAS in hepatoma cells selectively impairs induction of genes involved in adaptation to a hypoxic environment, notably the vascular endothelial growth factor (VEGF) gene, and results in retarded tumour growth and tumour vascular density in vivo. In mice, IPAS was predominantly expressed in Purkinje cells of the cerebellum and in corneal epithelium of the eye. Expression of IPAS in the cornea correlates with low levels of expression of the VEGF gene under hypoxic conditions. Application of an IPAS antisense oligonucleotide to the mouse cornea induced angiogenesis under normal oxygen conditions, and demonstrated hypoxia-dependent induction of VEGF gene expression in hypoxic corneal cells. These results indicate a previously unknown mechanism for negative regulation of angiogenesis and maintenance of an avascular phenotype.

  12. Genetic basis for glandular trichome formation in cotton

    PubMed Central

    Ma, Dan; Hu, Yan; Yang, Changqing; Liu, Bingliang; Fang, Lei; Wan, Qun; Liang, Wenhua; Mei, Gaofu; Wang, Lingjian; Wang, Haiping; Ding, Linyun; Dong, Chenguang; Pan, Mengqiao; Chen, Jiedan; Wang, Sen; Chen, Shuqi; Cai, Caiping; Zhu, Xiefei; Guan, Xueying; Zhou, Baoliang; Zhu, Shuijin; Wang, Jiawei; Guo, Wangzhen; Chen, Xiaoya; Zhang, Tianzhen

    2016-01-01

    Trichomes originate from epidermal cells and can be classified as either glandular or non-glandular. Gossypium species are characterized by the presence of small and darkly pigmented lysigenous glands that contain large amounts of gossypol. Here, using a dominant glandless mutant, we characterize GoPGF, which encodes a basic helix-loop-helix domain-containing transcription factor, that we propose is a positive regulator of gland formation. Silencing GoPGF leads to a completely glandless phenotype. A single nucleotide insertion in GoPGF, introducing a premature stop codon is found in the duplicate recessive glandless mutant (gl2gl3). The characterization of GoPGF helps to unravel the regulatory network of glandular structure biogenesis, and has implications for understanding the production of secondary metabolites in glands. It also provides a potential molecular basis to generate glandless seed and glanded cotton to not only supply fibre and oil but also provide a source of protein for human consumption. PMID:26795254

  13. Structure and Dimerization Properties of the Aryl Hydrocarbon Receptor PAS-A Domain

    PubMed Central

    Wu, Dalei; Potluri, Nalini; Kim, Youngchang

    2013-01-01

    The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor that binds to xenobiotics and responds by regulating the expression of gene programs required for detoxification and metabolism. AHR and its heterodimerization partner aryl hydrocarbon receptor nuclear translocator (ARNT) belong to the basic helix-loop-helix (bHLH)–PER-ARNT-SIM (PAS) family of transcription factors. Here we report the 2.55-Å-resolution crystal structure of the mouse AHR PAS-A domain, which represents the first AHR-derived protein structure. The AHR PAS-A domain forms a helix-swapped homodimer in the crystal and also in solution. Through a detailed mutational analysis of all interface residues, we identified several hydrophobic residues that are important for AHR dimerization and function. Our crystallographic visualization of AHR PAS-A dimerization leads us to propose a mode of heterodimerization with ARNT that is supported by both biochemical and cell-based data. Our studies also highlight the residues of other mammalian bHLH-PAS proteins that are likely involved in their homo- or heterodimerization. PMID:24001774

  14. Sim1 Inhibits Bone Formation by Enhancing the Sympathetic Tone in Male Mice

    PubMed Central

    Wang, Xunde; Wei, Wei; Zinn, Andrew R.

    2015-01-01

    Single-minded 1 (Sim1) is a basic helix-loop-helix Per-Arnt-Sim transcription factor that is important for neuronal development in the hypothalamus. Loss-of-function mutation of Sim1 causes early-onset obesity. However, it is unknown whether and how Sim1 regulates bone remodeling. In this study, we found that adult-onset Sim1 deletion increases bone formation, leading to high bone mass. In contrast, Sim1-overexpressing transgenic mice exhibit decreased bone formation and low bone mass. Sim1 does not directly regulate osteoblastogenesis, because bone marrow mesenchymal stem cells from Sim1 mutant mice display a normal capacity for osteoblast differentiation. Instead, Sim1 inhibits bone formation via stimulating the sympathetic nervous system, because sympathetic tone is decreased by Sim1 deletion but increased by Sim1 overexpression. Treatment with the β-adrenergic agonist isoproterenol effectively reverses the high bone mass in Sim1-knockout mice. These findings reveal Sim1 as a critical yet previously unrecognized modulator of skeletal homeostasis that functions through a central relay. PMID:25607894

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

    PubMed Central

    Chu, Khoi; Tsai, Ming-Jer

    2005-01-01

    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 β-cell function. PMID:15793245

  16. Effect of the g.-723G-->T polymorphism in the bovine myogenic factor 5 (Myf5) gene promoter region on gene transcript level in the longissimus dorsi muscle and on meat traits of Polish Holstein-Friesian cattle.

    PubMed

    Robakowska-Hyzorek, Dagmara; Oprzadek, Jolanta; Zelazowska, Beata; Olbromski, Rafał; Zwierzchowski, Lech

    2010-06-01

    Myogenic factor 5 (Myf5), a product of the Myf5 gene, belongs to the MRF family of basic helix-loop-helix transcription factors that regulate myogenesis. Their roles in muscle growth and development make their genes candidates for molecular markers of meat production in livestock, but nucleotide sequence polymorphism has not been thoroughly studied in MRF genes. We detected four single nucleotide polymorphisms (SNPs) within exon 1 of the Myf5 gene, encoding the NH-terminal transactivation domain of the Myf5 protein. Three of these mutations change the amino acid sequence. The distribution of these SNPs was highly skewed in cattle populations; most of the mutations were found in only a few or even single individuals. Of the nine SNPs found in the promoter region of Myf5, one (transversion g.-723G-->T) was represented by all three genotypes distributed in the cattle populations studied. This polymorphism showed an influence on Myf5 gene expression in the longissimus dorsi muscle and was associated with sirloin weight and fat weight in sirloin in carcasses of Holstein-Friesian cattle. PMID:20127165

  17. Disruption of neurogenesis and cortical development in transgenic mice misexpressing Olig2, a gene in the Down syndrome critical region.

    PubMed

    Liu, Wei; Zhou, Hui; Liu, Lei; Zhao, Chuntao; Deng, Yaqi; Chen, Lina; Wu, Laiman; Mandrycky, Nicole; McNabb, Christopher T; Peng, Yuanbo; Fuchs, Perry N; Lu, Jie; Sheen, Volney; Qiu, Mengsheng; Mao, Meng; Lu, Q Richard

    2015-05-01

    The basic helix-loop-helix (bHLH) transcription factor Olig2 is crucial for mammalian central nervous system development. Human ortholog OLIG2 is located in the Down syndrome critical region in trisomy 21. To investigate the effect of Olig2 misexpression on brain development, we generated a developmentally regulated Olig2-overexpressing transgenic line with a Cre/loxP system. The transgenic mice with Olig2 misexpression in cortical neural stem/progenitor cells exhibited microcephaly, cortical dyslamination, hippocampus malformation, and profound motor deficits. Ectopic misexpression of Olig2 impaired cortical progenitor proliferation and caused precocious cell cycle exit. Massive neuronal cell death was detected in the developing cortex of Olig2-misexpressing mice. In addition, Olig2 misexpression led to a significant downregulation of neuronal specification factors including Ngn1, Ngn2 and Pax6, and a defect in cortical neurogenesis. Chromatin-immunoprecipitation and sequencing (ChIP-Seq) analysis indicates that Olig2 directly targets the promoter and/or enhancer regions of Nfatc4, Dscr1/Rcan1 and Dyrk1a, the critical neurogenic genes that contribute to Down syndrome phenotypes, and inhibits their expression. Together, our study suggests that Olig2 misexpression in neural stem cells elicits neurogenesis defects and neuronal cell death, which may contribute to developmental disorders including Down syndrome, where OLIG2 is triplicated on chromosomal 21. PMID:25747816

  18. 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

    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.

    2013-01-01

    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

  19. NeuroD1 is required for survival of photoreceptors but not pinealocytes: results from targeted gene deletion studies.

    PubMed

    Ochocinska, Margaret J; Muñoz, Estela M; Veleri, Shobi; Weller, Joan L; Coon, Steven L; Pozdeyev, Nikita; Iuvone, P Michael; Goebbels, Sandra; Furukawa, Takahisa; Klein, David C

    2012-10-01

    NeuroD1 encodes a basic helix-loop-helix transcription factor involved in the development of neural and endocrine structures, including the retina and pineal gland. To determine the effect of NeuroD1 knockout in these tissues, a Cre/loxP recombination strategy was used to target a NeuroD1 floxed gene and generate NeuroD1 conditional knockout (cKO) mice. Tissue specificity was conferred using Cre recombinase expressed under the control of the promoter of Crx, which is selectively expressed in the pineal gland and retina. At 2 months of age, NeuroD1 cKO retinas have a dramatic reduction in rod- and cone-driven electroretinograms and contain shortened and disorganized outer segments; by 4 months, NeuroD1 cKO retinas are devoid of photoreceptors. In contrast, the NeuroD1 cKO pineal gland appears histologically normal. Microarray analysis of 2-month-old NeuroD1 cKO retina and pineal gland identified a subset of genes that were affected 2-100-fold; in addition, a small group of genes exhibit altered differential night/day expression. Included in the down-regulated genes are Aipl1, which is necessary to prevent retinal degeneration, and Ankrd33, whose protein product is selectively expressed in the outer segments. These findings suggest that NeuroD1 may act through Aipl1 and other genes to maintain photoreceptor homeostasis. PMID:22784109

  20. NeuroD1 is required for survival of photoreceptors but not pinealocytes: Results from targeted gene deletion studies

    PubMed Central

    Ochocinska, Margaret J.; Muñoz, Estela M.; Veleri, Shobi; Weller, Joan L.; Coon, Steven L.; Pozdeyev, Nikita; Iuvone, P. Michael; Goebbels, Sandra; Furukawa, Takahisa; Klein, David C.

    2012-01-01

    NeuroD1 encodes a basic helix-loop-helix (bHLH) transcription factor involved in the development of neural and endocrine structures, including the retina and pineal gland. To determine the effect of NeuroD1 knockout in these tissues, a Cre/loxP recombination strategy was used to target a NeuroD1 floxed gene and generate NeuroD1 conditional knockout (cKO) mice. Tissue specificity was conferred using Cre recombinase expressed under the control of the promoter of Crx, which is selectively expressed in the pineal gland and retina. At two months of age NeuroD1 cKO retinas have a dramatic reduction in rod- and cone-driven electroretinograms and contain shortened and disorganized outer segments; by four months NeuroD1 cKO retinas are devoid of photoreceptors. In contrast, the NeuroD1 cKO pineal gland appears histologically normal. Microarray analysis of two-month-old NeuroD1 cKO retina and pineal gland identified a subset of genes that were affected 2- to 100-fold; in addition, a small group of genes exhibit altered differential night/day expression. Included in the down-regulated genes are Aipl1, which is necessary to prevent retinal degeneration, and Ankrd33, which is selectively expressed in the outer segments. These findings suggest that NeuroD1 may act through Aipl1 and other genes to maintain photoreceptor homeostasis. PMID:22784109

  1. Regulation of Motor Neuron Specification by GSK3-Mediated Phosphorylation of Neurogenin 2

    PubMed Central

    Ma, Yong-Chao; Song, Mi-Ryoung; Park, Jin P.; Ho, Hsin-Yi Henry; Hu, Linda; Kurtev, Martin V.; Zieg, Janine; Ma, Qiufu; Pfaff, Samuel L.; Greenberg, Michael E.

    2008-01-01

    SUMMARY The mechanisms by which proneural basic helix-loop-helix (bHLH) factors control neurogenesis have been characterized, but it is not known how they specify neuronal cell-type identity. Here we provide evidence that two conserved serine residues on the bHLH factor neurogenin 2 (Ngn2), S231 and S234, are phosphorylated during motor neuron differentiation. In knock-in mice in which S231 and S234 of Ngn2 were mutated to alanines, neurogenesis occurs normally but motor neuron specification is impaired. The phosphorylation of Ngn2 at S231 and S234 facilitates the interaction of Ngn2 with LIM homeodomain transcription factors to specify motor neuron identity. The phosphorylation-dependent cooperativity between Ngn2 and homeodomain transcription factors represents a novel mode of transcriptional regulation, and may be a general mechanism by which the activities of bHLH and homeodomain proteins are temporally and spatially integrated to generate the wide diversity of cell types that are a hallmark of the nervous system. PMID:18400164

  2. Neurogenin2 Directs Granule Neuroblast Production and Amplification while NeuroD1 Specifies Neuronal Fate during Hippocampal Neurogenesis

    PubMed Central

    Roybon, Laurent; Hjalt, Tord; Stott, Simon; Guillemot, Francois

    2009-01-01

    The specification and differentiation of dentate gyrus granule neurons in the hippocampus require temporally and spatially coordinated actions of both intrinsic and extrinsic molecules. The basic helix-loop-helix transcription factor Neurogenin2 (Ngn2) and NeuroD1 are key regulators in these processes. Based on existing classification, we analyzed the molecular events occurring during hippocampal neurogenesis, primarily focusing on juvenile animals. We found that Ngn2 is transiently expressed by late type-2a amplifying progenitors. The Ngn2 progenies mature into hippocampal granule neurons. Interestingly, the loss of Ngn2 at early stages of development leads to a robust reduction in neurogenesis, but does not disturb granule neuron maturation per se. We found that the role of Ngn2 is to maintain progenitors in an undifferentiated state, allowing them to amplify prior to their maturation into granule neurons upon NeuroD1 induction. When we overexpressed Ngn2 and NeuroD1 in vivo, we found NeuroD1 to exhibit a more pronounced neuron-inductive effect, leading to granule neuron commitment, than that displayed by Ngn2. Finally, we observed that all markers expressed during the transcriptional control of hippocampal neurogenesis in rodents are also present in the human hippocampus. Taken together, we demonstrate a critical role of for Ngn2 and NeuroD1 in controlling neuronal commitment and hippocampal granule neuroblast formation, both during embryonic development and in post-natal hippocampal granule neurogenesis. PMID:19274100

  3. MYC in breast tumor progression

    PubMed Central

    Chen, Yinghua; Olopade, Olufunmilayo I

    2008-01-01

    Breast cancer is the second leading cause of cancer deaths and is the most frequently diagnosed cancer in women of industrialized nations. Breast cancer progression is a multistep process involving genetic and epigenetic alterations that drive normal breast cells into highly malignant derivatives with metastatic potential. MYC is a proto-oncogene whose protein product contains a basic helix-loop-helix domain. MYC functions as a transcription factor regulating up to 15% of all human genes. MYC is regulated at multiple levels, and the protein is a downstream effector of several signaling pathways. In breast cancer cells, MYC target genes are involved in cell growth, transformation, angiogenesis and cell-cycle control. BRCA1 is linked to transcriptional regulation through interaction with MYC. Although the relationship between amplification and overexpression is not clearly delineated, MYC amplification is significantly correlated with aggressive tumor phenotypes and poor clinical outcomes. MYC amplification is emerging as an important predictor of response to HER2-targeted therapies and its role in BRCA1-associated breast cancer makes it an important target in basal-like/triple-negative breast cancers. PMID:18925859

  4. CCAR1 is required for Ngn3-mediated endocrine differentiation

    SciTech Connect

    Lu, Chung-Kuang; Lai, Yi-Chyi; Lin, Yung-Fu; Chen, Hau-Ren; Chiang, Ming-Ko

    2012-02-10

    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.

  5. Phylogenetic analysis and classification of the fungal bHLH domain.

    PubMed

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

    2012-05-01

    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 www.fungalgenomics.ncsu.edu. PMID:22114358

  6. Overexpression of OsPIL15, a phytochrome-interacting factor-like protein gene, represses etiolated seedling growth in rice.

    PubMed

    Zhou, Jinjun; Liu, Qianqian; Zhang, Fang; Wang, Yingying; Zhang, Shiyong; Cheng, Huimin; Yan, Lihua; Li, Li; Chen, Fan; Xie, Xianzhi

    2014-04-01

    Phytochrome-interacting factors (PIFs) regulate an array of developmental responses ranging from seed germination to vegetational architecture in Arabidopsis. However, information regarding the functions of the PIF family in monocots has not been widely reported. Here, we investigate the roles of OsPIL15, a member of the rice (Oryza sativa L. cv. Nipponbare) PIF family, in regulating seedling growth. OsPIL15 encodes a basic helix-loop-helix factor localized in the nucleus. OsPIL15-OX seedlings exhibit an exaggerated shorter aboveground part and undeveloped root system relative to wild-type seedlings, suggesting that OsPIL15 represses seedling growth in the dark. Microarray analysis combined with gene ontology analysis revealed that OsPIL15 represses a set of genes involved in auxin pathways and cell wall organization or biogenesis. Given the important roles of the auxin pathway and cell wall properties in controlling plant growth, we speculate that OsPIL15 represses seedling growth likely by regulating the auxin pathway and suppressing cell wall organization in etiolated rice seedlings. Additionally, exposure to red light or far-red light relieved growth retardation and promoted seedling elongation in the OsPIL15-OX lines, despite higher levels of OsPIL15 transcripts under red light and far-red light than in the dark. These results suggest that light regulation of OsPIL15 expression is probably involved in photomorphogenesis in rice. PMID:24279300

  7. BARREN STALK FASTIGIATE1 Is an AT-Hook Protein Required for the Formation of Maize Ears[W][OA

    PubMed Central

    Gallavotti, Andrea; Malcomber, Simon; Gaines, Craig; Stanfield, Sharon; Whipple, Clinton; Kellogg, Elizabeth; Schmidt, Robert J.

    2011-01-01

    Ears are the seed-bearing inflorescences of maize (Zea mays) plants and represent a crucial component of maize yield. The first step in the formation of ears is the initiation of axillary meristems in the axils of developing leaves. In the classic maize mutant barren stalk fastigiate1 (baf1), first discovered in the 1950s, ears either do not form or, if they do, are partially fused to the main stalk. We positionally cloned Baf1 and found that it encodes a transcriptional regulator containing an AT-hook DNA binding motif. Single coorthologs of Baf1 are found in syntenic regions of brachypodium (Brachypodium distachyon), rice (Oryza sativa), and sorghum (Sorghum bicolor), suggesting that the gene is likely present in all cereal species. Protein–protein interaction assays suggest that BAF1 is capable of forming homodimers and heterodimers with other members of the AT-hook family. Another transcriptional regulator required for ear initiation is the basic helix-loop-helix protein BARREN STALK1 (BA1). Genetic and expression analyses suggest that Baf1 is required to reach a threshold level of Ba1 expression for the initiation of maize ears. We propose that Baf1 functions in the demarcation of a boundary region essential for the specification of a stem cell niche. PMID:21540434

  8. Diterpenoid phytoalexin factor, a bHLH transcription factor, plays a central role in the biosynthesis of diterpenoid phytoalexins in rice.

    PubMed

    Yamamura, Chihiro; Mizutani, Emi; Okada, Kazunori; Nakagawa, Hitoshi; Fukushima, Setsuko; Tanaka, Atsunori; Maeda, Satoru; Kamakura, Takashi; Yamane, Hisakazu; Takatsuji, Hiroshi; Mori, Masaki

    2015-12-01

    Rice (Oryza sativa) produces diterpenoid phytoalexins (DPs), momilactones and phytocassanes as major phytoalexins. Accumulation of DPs is induced in rice by blast fungus infection, copper chloride or UV light. Here, we describe a rice transcription factor named diterpenoid phytoalexin factor (DPF), which is a basic helix-loop-helix (bHLH) transcription factor. The gene encoding DPF is expressed mainly in roots and panicles, and is inducible in leaves by blast infection, copper chloride or UV. Expression of all DP biosynthetic genes and accumulation of momilactones and phytocassanes were remarkably increased and decreased in DPF over-expressing and DPF knockdown rice, respectively. These results clearly demonstrated that DPF positively regulates DP accumulation via transcriptional regulation of DP biosynthetic genes, and plays a central role in the biosynthesis of DPs in rice. Furthermore, DPF activated the promoters of COPALYL DIPHOSPHATE SYNTHASE2 (CPS2) and CYTOCHROME P450 MONOOXYGENASE 99A2 (CYP99A2), whose products are implicated in the biosynthesis of phytocassanes and momilactones, respectively. Mutations in the N-boxes in the CPS2 upstream region, to which several animal bHLH transcription factors bind, decreased CPS2 transcription, indicating that DPF positively regulates CPS2 transcription through the N-boxes. In addition, DPF partly regulates CYP99A2 through the N-box. This study demonstrates that DPF acts as a master transcription factor in DP biosynthesis. PMID:26506081

  9. Enhanced Generation of Myeloid Lineages in Hematopoietic Differentiation from Embryonic Stem Cells by Silencing Transcriptional Repressor Twist-2

    PubMed Central

    Sharabi, Andrew B.; Lee, Sung-Hyung; Goodell, Margaret A.; Huang, Xue F.

    2009-01-01

    Abstract The self-renewal and multilineage differentiation of embryonic stem cells (ESC) is largely governed by transcription factors or repressors. Extensive efforts have focused on elucidating critical factors that control the differentiation of specific cell lineages, for instance, myeloid lineages in hematopoietic development. In this study, we found that Twist-2, a basic helix-loop-helix (bHLH) transcription factor, plays a critical role in inhibiting the differentiation of ESC. Murine ES cells, in which Twist-2 expression is silenced by lentivirally delivered shRNA, exhibit an enhanced formation of primary embryoid bodies (EB) and enhanced differentiation into mesodermally derived hematopoietic colonies. Furthermore, Twist-2 silenced (LV-siTwist-2) ESC display significantly increased generation of myeloid lineages (Gr-1+ and F4/80+ cells) during in vitro hematopoietic differentiation. Treatment with the Toll-like receptor (TLR) 4 ligand synergistically stimulates the generation of primary EB formation as well as of hematopoietic progenitors differentiated from LV-siTwist-2 ES cells. Thus, this study reveals the critical role of the transcriptional repressor Twist-2 in regulating the development of myeloid lineage in hematopoietic differentiation from ESC. This study also suggests a potential strategy for directional differentiation of ESC by inhibiting a transcriptional repressor. PMID:20025523

  10. Is overexpression of TWIST, a transcriptional factor, a prognostic biomarker of head and neck carcinoma? Evidence from fifteen studies

    PubMed Central

    Zhuo, Xianlu; Luo, Huanli; Chang, Aoshuang; Li, Dairong; Zhao, Houyu; Zhou, Qi

    2015-01-01

    TWIST, a basic helix-loop-helix transcription factor, has been indicated to play a critical role in the progression of numerous malignant disorders. Published data on the significance of TWIST expression in head and neck carcinoma (HNC) risk have yielded conflicting results. Thus, we conducted a quantitative meta-analysis to obtain a precise estimate of this subject. After systematic searching and screening, a total of fifteen studies using immunohistochemistry for TWIST detection were included. The results showed that TWIST positive expression rate in HNC tissues was higher than that in normal tissues. TWIST expression might have a correlation with clinical features such as low differentiation, advanced clinical stage, presence of lymph node metastasis, distant metastasis and local recurrence (P < 0.05) , but not with age, gender, T stage and smoking as well as drinking (P > 0.05). In addition, over-expression of TWIST was a prognostic factor for HNC (HR = 1.92, 95% CI = 1.13–3.25). The data suggested that TWIST might play critical roles in cancer progression and act as a prognostic factor for HNC patients. PMID:26656856

  11. Sn, a maize bHLH gene, modulates anthocyanin and condensed tannin pathways in Lotus corniculatus.

    PubMed

    Robbins, Mark Paske; Paolocci, Francesco; Hughes, John-Wayne; Turchetti, Valentina; Allison, Gordon; Arcioni, Sergio; Morris, Phillip; Damiani, Francesco

    2003-01-01

    Anthocyanins and condensed tannins are major flavonoid end-products in higher plants. While the transactivation of anthocyanins by basic helix-loop-helix (bHLH) transcription factors is well documented, very little is known about the transregulation of the pathway to condensed tannins. The present study analyses the effect of over-expressing an Sn transgene in Lotus corniculatus, a model legume, with the aim of studying the regulation of anthocyanin and tannin end-products. Contrary to expectation, effects on anthocyanin accumulation were subtle and restricted to the leaf midrib, leaf base and petiole tissues. However, the accumulation of condensed tannin polymers was dramatically enhanced in the leaf blade and this increase was accompanied by a 50-fold increase in the number of tannin-containing cells in this tissue. A detailed analysis of selected lines indicated that this transactivational phenotype correlated with high steady-state transcript levels of the introduced transgene and the introduction of a single copy of the CaMV35S-Sn construct into these clonal genotypes. While the levels of condensed tannins in leaves were increased by up to 1% of the dry weight, other major secondary end-products (flavonols, lignins and inducible phytoalexins) were unaltered in transactivated lines. These results give an initial insight into the developmental and higher-order regulation of polyphenolic metabolism in Lotus and other higher plant species. PMID:12493851

  12. RSL Class I Genes Controlled the Development of Epidermal Structures in the Common Ancestor of Land Plants.

    PubMed

    Proust, Hélène; Honkanen, Suvi; Jones, Victor A S; Morieri, Giulia; Prescott, Helen; Kelly, Steve; Ishizaki, Kimitsune; Kohchi, Takayuki; Dolan, Liam

    2016-01-11

    The colonization of the land by plants, sometime before 470 million years ago, was accompanied by the evolution tissue systems [1-3]. Specialized structures with diverse functions-from nutrient acquisition to reproduction-derived from single cells in the outermost layer (epidermis) were important sources of morphological innovation at this time [2, 4, 5]. In extant plants, these structures may be unicellular extensions, such as root hairs or rhizoids [6-9], or multicellular structures, such as asexual propagules or secretory hairs (papillae) [10-12]. Here, we show that a ROOTHAIR DEFECTIVE SIX-LIKE (RSL) class I basic helix-loop-helix transcription factor positively regulates the development of the unicellular and multicellular structures that develop from individual cells that expand out of the epidermal plane of the liverwort Marchantia polymorpha; mutants that lack MpRSL1 function do not develop rhizoids, slime papillae, mucilage papillae, or gemmae. Furthermore, we discovered that RSL class I genes are also required for the development of multicellular axillary hairs on the gametophyte of the moss Physcomitrella patens. Because class I RSL proteins also control the development of rhizoids in mosses and root hairs in angiosperms [13, 14], these data demonstrate that the function of RSL class I genes was to control the development of structures derived from single epidermal cells in the common ancestor of the land plants. Class I RSL genes therefore controlled the generation of adaptive morphological diversity as plants colonized the land from the water. PMID:26725198

  13. Spatiotemporal expression of Math6 during mouse embryonic development.

    PubMed

    Wang, Baigang; Balakrishnan-Renuka, Ajeesh; Napirei, Markus; Theiss, Carsten; Brand-Saberi, Beate

    2015-06-01

    The basic helix-loop-helix transcription factor Math6 was shown to have important regulatory functions during many developmental events. However, a systematic description of Math6 expression during mouse embryonic development is up to now still lacking. We carried out this study to show Math6 expression at different stages of mouse embryonic development aiming to provide a wide insight into the regulatory functions during the mouse organogenesis. Using immunohistochemistry, we could show that Math6 expression is activated in the inner cell mass at the blastocyst stage and in the neural tube as well as somatic and splanchnic mesoderm at stage E8.5. At stages E8.5 and E10.5, Math6 transcripts were detected in the myotome, neural tube, pharyngeal arches, foregut and heart. At stages E11.5 and E12.5, Math6 transcripts were accumulated in the developing brain, heart, limb buds and liver. The heterozygous transgenic mouse embryos carrying EGFP-Cre under the Math6 promoter were used to analyze Math6 expression at later stages by means of immunohistochemistry against EGFP protein. EGFP was observed in the neural tube, heart, lung, skeletal muscle, skin, cartilage, trachea and aorta. We have observed Math6 expression in various organs at early and late stages of mouse development, which illustrates the involvement of Math6 in multiple developmental events. PMID:25578518

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

    PubMed Central

    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

    2015-01-01

    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

  15. MDL-1, a growth- and tumor-suppressor, slows aging and prevents germline hyperplasia and hypertrophy in C. elegans

    PubMed Central

    Riesen, Michèle; Feyst, Inna; Rattanavirotkul, Nattaphong; Ezcurra, Marina; Tullet, Jennifer M.A.; Papatheodorou, Irene; Ziehm, Matthias; Au, Catherine; Gilliat, Ann F.; Hellberg, Josephine; Thornton, Janet M.; Gems, David

    2014-01-01

    In C. elegans, increased lifespan in daf-2 insulin/IGF-1 receptor mutants is accompanied by up-regulation of the MDL-1 Mad basic helix-loop-helix leucine zipper transcription factor. Here we describe the role of mdl-1 in C. elegans germline proliferation and aging. The deletion allele mdl-1(tm311) shortened lifespan, and did so significantly more so in long-lived daf-2 mutants implying that mdl-1(+) contributes to effects of daf-2 on lifespan. mdl-1 mutant hermaphrodites also lay increased numbers of unfertilized oocytes. During aging, unfertilized oocytes in the uterus develop into tumors, whose development was accelerated by mdl-1(tm311). Opposite phenotypes were seen in daf-2 mutants, i.e. mdl-1 and daf-2 mutant germlines are hyperplastic and hypoplastic, respectively. Thus, MDL-1, like its mammalian orthologs, is an inhibitor of cell proliferation and growth that slows progression of an age-related pathology in C. elegans (uterine tumors). In addition, intestine-limited rescue of mdl-1 increased lifespan but not to wild type levels. Thus, mdl-1 likely acts both in the intestine and the germline to influence age-related mortality. PMID:24531613

  16. MDL-1, a growth- and tumor-suppressor, slows aging and prevents germline hyperplasia and hypertrophy in C. elegans.

    PubMed

    Riesen, Michèle; Feyst, Inna; Rattanavirotkul, Nattaphong; Ezcurra, Marina; Tullet, Jennifer M A; Papatheodorou, Irene; Ziehm, Matthias; Au, Catherine; Gilliat, Ann F; Hellberg, Josephine; Thornton, Janet M; Gems, David

    2014-02-01

    In C. elegans, increased lifespan in daf-2 insulin/IGF-1 receptor mutants is accompanied by up-regulation of the MDL-1 Mad basic helix-loop-helix leucine zipper transcription factor. Here we describe the role of mdl-1 in C. elegans germline proliferation and aging. The deletion allele mdl-1(tm311) shortened lifespan, and did so significantly more so in long-lived daf-2 mutants implying that mdl-1(+) contributes to effects of daf-2 on lifespan. mdl-1 mutant hermaphrodites also lay increased numbers of unfertilized oocytes. During aging, unfertilized oocytes in the uterus develop into tumors, whose development was accelerated by mdl-1(tm311). Opposite phenotypes were seen in daf-2 mutants, i.e. mdl-1 and daf-2 mutant germlines are hyperplastic and hypoplastic, respectively. Thus, MDL-1, like its mammalian orthologs, is an inhibitor of cell proliferation and growth that slows progression of an age-related pathology in C. elegans (uterine tumors). In addition, intestine-limited rescue of mdl-1 increased lifespan but not to wild type levels. Thus, mdl-1 likely acts both in the intestine and the germline to influence age-related mortality. PMID:24531613

  17. The bHLH transcription factor hand is required for proper wing heart formation in Drosophila.

    PubMed

    Tögel, Markus; Meyer, Heiko; Lehmacher, Christine; Heinisch, Jürgen J; Pass, Günther; Paululat, Achim

    2013-09-15

    The Hand basic helix-loop-helix transcription factors play an important role in the specification and patterning of various tissues in vertebrates and invertebrates. Here, we have investigated the function of Hand in the development of the Drosophila wing hearts which consist of somatic muscle cells as well as a mesodermally derived epithelium. We found that Hand is essential in both tissues for proper organ formation. Loss of Hand leads to a reduced number of cells in the mature organ and loss of wing heart functionality. In wing heart muscles Hand is required for the correct positioning of attachment sites, the parallel alignment of muscle cells, and the proper orientation of myofibrils. At the protein level, α-Spectrin and Dystroglycan are misdistributed suggesting a defect in the costameric network. Hand is also required for proper differentiation of the wing heart epithelium. Additionally, the handC-GFP reporter line is not active in the mutant suggesting an autoregulatory role of Hand in wing hearts. Finally, in a candidate-based RNAi mediated knock-down approach we identified Daughterless and Nautilus as potential dimerization partners of Hand in wing hearts. PMID:23747982

  18. The bHLH Transcription Factor Hand Regulates the Expression of Genes Critical to Heart and Muscle Function in Drosophila melanogaster

    PubMed Central

    Hallier, Benjamin; Hoffmann, Julia; Roeder, Thomas; Tögel, Markus; Meyer, Heiko; Paululat, Achim

    2015-01-01

    Hand proteins belong to the highly conserved family of basic Helix-Loop-Helix transcription factors and are critical to distinct developmental processes, including cardiogenesis and neurogenesis in vertebrates. In Drosophila melanogaster a single orthologous hand gene is expressed with absence of the respective protein causing semilethality during early larval instars. Surviving adult animals suffer from shortened lifespan associated with a disorganized myofibrillar structure being apparent in the dorsal vessel, the wing hearts and in midgut tissue. Based on these data, the major biological significance of Hand seems to be related to muscle development, maintenance or function; however, up to now the physiological basis for Hand functionality remains elusive. Thus, the identification of genes whose expression is, directly or indirectly, regulated by Hand has considerable relevance with respect to understanding its biological functionality in flies and vertebrates. Beneficially, hand mutants are viable and exhibit affected tissues, which renders Drosophila an ideal model to investigate up- or downregulated target genes by a comparative microarray approach focusing on the respective tissues from mutant specimens. Our present work reveals for the first time that Drosophila Hand regulates the expression of numerous genes of diverse physiological relevancy, including distinct factors required for proper muscle development and function such as Zasp52 or Msp-300. These results relate Hand activity to muscle integrity and functionality and may thus be highly beneficial to the evaluation of corresponding hand phenotypes. PMID:26252215

  19. Stra13 and Sharp-1, the non-grouchy regulators of development and disease.

    PubMed

    Ow, Jin Rong; Tan, Yong Hua; Jin, Yu; Bahirvani, Avinash G; Taneja, Reshma

    2014-01-01

    Stra13 and Sharp-1 are transcriptional repressors that share domain structure similarity with members of the basic helix-loop-helix-Orange subfamily. In contrast to other members that include Hes and Hey proteins, transcriptional repression mediated by Stra13 and Sharp-1 does not involve recruitment of the corepressor Groucho. Both proteins undergo sumoylation at evolutionarily conserved sites, and this posttranslational modification serves as a platform for association with chromatin-modifying enzymes including histone deacetylases and histone methyltransferases. In addition to being widely expressed during embryonic development and in adult tissues, the expression of both genes is induced by a number of stimuli. Loss-of-function and gain-of-function studies have demonstrated their function in cellular differentiation and regeneration, in regulation of circadian rhythms, immune homeostasis, and metabolism. Given their diverse physiological functions in several tissues, it is not surprising that deregulated expression of Stra13 and Sharp-1 is apparent in human pathologies. Here, we review our current understanding of their cellular functions that suggest a requirement in maintenance of tissue homeostasis. PMID:25248481

  20. Molecular cloning and characterization of the Myf5 gene in sea perch (Lateolabrax japonicus).

    PubMed

    Ye, Han-Qing; Chen, Song-Lin; Xu, Jian-Yong

    2007-07-01

    The cDNA of myogenic factor (Myf5) was isolated from sea perch (Lateolabrax japonicus) using Reverse-transcription Polymerase Chain Reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The 5' flanking sequence of the cDNA contains a TATA box, GC box, CAAT box, several E box sites and muscle-specific regulatory elements determined by genome walking. The Myf5 gene consists of 3 exons and 2 introns. The open reading frame was found to code a protein with 238 amino-acid residues, containing the conserved basic helix-loop-helix domain (bHLH). RT-PCR indicated the Myf5 was highly expressed in muscle, and weakly expressed in brain, eyes, spleen, gill, liver, kidney, intestine and heart. In early embryonic stages, Myf5 mRNA transcripts are highly detectable in the early gastrula stage while decreasing up to a low level at the late gastrula stage, subsequently greatly increased up to the highest level in the somites stage, then gradually decreases from the tail-bud stage to 15 d larvae after hatching, but they are still detectable. Further, Myf5 mRNA was expressed in several sea perch cell lines such as LJES1, LJHK, LJH-1, LJH-2, LJS, LJL, although its expression level varied greatly among different cell lines. PMID:17395511

  1. The myogenic repressor gene Holes in muscles is a direct transcriptional target of Twist and Tinman in the Drosophila embryonic mesoderm

    PubMed Central

    Elwell, Jennifer A.; Lovato, TyAnna L.; Adams, Melanie M.; Baca, Erica M.; Lee, Thai; Cripps, Richard M.

    2015-01-01

    Understanding the regulatory circuitry controlling myogenesis is critical to understanding developmental mechanisms and developmentally-derived diseases. We analyzed the transcriptional regulation of a Drosophila myogenic repressor gene, Holes in muscles (Him). Previously, Him was shown to inhibit Myocyte enhancer factor-2 (MEF2) activity, and is expressed in myoblasts but not differentiating myotubes. We demonstrate that different phases of Him embryonic expression arise through the actions of different enhancers, and we characterize the enhancer required for its early mesoderm expression. This Him early mesoderm enhancer contains two conserved binding sites for the basic helix-loop-helix regulator Twist, and one binding site for the NK homeodomain protein Tinman. The sites for both proteins are required for enhancer activity in early embryos. Twist and Tinman activate the enhancer in tissue culture assays, and ectopic expression of either factor is sufficient to direct ectopic expression of a Him-lacZ reporter, or of the endogenous Him gene. Moreover, sustained expression of twist expression in the mesoderm up-regulates mesodermal Him expression in late embryos. Our findings provide a model to define mechanistically how Twist can both promotes myogenesis through direct activation of Mef2, and can place a brake on myogenesis, through direct activation of Him. PMID:25704510

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

    PubMed

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

    2015-01-01

    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

  3. ICE1 of Poncirus trifoliata functions in cold tolerance by modulating polyamine levels through interacting with arginine decarboxylase.

    PubMed

    Huang, Xiao-San; Zhang, Qinghua; Zhu, Dexin; Fu, Xingzheng; Wang, Min; Zhang, Qian; Moriguchi, Takaya; Liu, Ji-Hong

    2015-06-01

    ICE1 (Inducer of CBF Expression 1) encodes a MYC-like basic helix-loop-helix transcription factor that acts as a central regulator of cold response. In this study, we elucidated the function and underlying mechanisms of PtrICE1 from trifoliate orange [Poncirus trifoliata (L.) Raf.]. PtrICE1 was upregulated by cold, dehydration, and salt, with the greatest induction under cold conditions. PtrICE1 was localized in the nucleus and could bind to a MYC-recognizing sequence. Ectopic expression of PtrICE1 in tobacco and lemon conferred enhanced tolerance to cold stresses at either chilling or freezing temperatures. Yeast two-hybrid screening revealed that 21 proteins belonged to the PtrICE1 interactome, in which PtADC (arginine decarboxylase) was confirmed as a bona fide protein interacting with PtrICE1. Transcript levels of ADC genes in the transgenic lines were slightly elevated under normal growth condition but substantially increased under cold conditions, consistent with changes in free polyamine levels. By contrast, accumulation of the reactive oxygen species, H2O2 and O2 (-), was appreciably alleviated in the transgenic lines under cold stress. Higher activities of antioxidant enzymes, such as superoxide dismutase and catalase, were detected in the transgenic lines under cold conditions. Taken together, these results demonstrated that PtrICE1 plays a positive role in cold tolerance, which may be due to modulation of polyamine levels through interacting with the ADC gene. PMID:25873670

  4. Differential Contribution of Transcription Factors to Arabidopsis thaliana Defense Against Spodoptera littoralis.

    PubMed

    Schweizer, Fabian; Bodenhausen, Natacha; Lassueur, Steve; Masclaux, Frédéric G; Reymond, Philippe

    2013-01-01

    In response to insect herbivory, Arabidopsis plants activate the synthesis of the phytohormone jasmonate-isoleucine, which binds to a complex consisting of the receptor COI1 and JAZ repressors. Upon proteasome-mediated JAZ degradation, basic helix-loop-helix transcription factors (TFs) MYC2, MYC3, and MYC4 become activated and this results in the expression of defense genes. Although the jasmonate (JA) pathway is known to be essential for the massive transcriptional reprogramming that follows herbivory, there is however little information on other TFs that are required for defense against herbivores and whether they contribute significantly to JA-dependent defense gene expression. By transcriptome profiling, we identified 41 TFs that were induced in response to herbivory by the generalist Spodoptera littoralis. Among them, nine genes, including WRKY18, WRKY40, ANAC019, ANAC055, ZAT10, ZAT12, AZF2, ERF13, and RRTF1, were found to play a significant role in resistance to S. littoralis herbivory. Compared to the triple mutant myc234 that is as sensitive as coi1-1 to herbivory, knockout lines of these nine TFs were only partially more sensitive to S. littoralis but, however, some displayed distinct gene expression changes at the whole-genome level. Data thus reveal that MYC2, MYC3, and MYC4 are master regulators of Arabidopsis resistance to a generalist herbivore and identify new genes involved in insect defense. PMID:23382734

  5. The aryl hydrocarbon receptor (AhR) pathway as a regulatory pathway for cell adhesion and matrix metabolism

    PubMed Central

    Kung, Tiffany; Murphy, K.A.; White, L.A.

    2009-01-01

    The aryl hydrocarbon receptor (AhR) is an orphan receptor in the basic-helix-loop-helix PAS family of transcriptional regulators. Although the endogenous regulator of this pathway has not been identified, the AhR is known to bind and be activated by a variety of compounds ranging from environmental contaminants to flavanoids. The function of this receptor is still unclear; however, animal models indicate that the AhR is important for normal development. One hypothesis is that the AhR senses cellular stress and initiates the cellular response by altering gene expression and inhibiting cell cycle progression and that activation of the AhR by exogenous environmental chemicals results in the dysregulation of this normal function. In this review we will examine the role of the AhR in the regulation of genes and proteins involved in cell adhesion and matrix remodeling, and discuss the implications of these changes in development and disease. In addition, we will discuss evidence suggesting that the AhR pathway is responsive to changes in matrix composition as well as cell-cell and cell-matrix interactions. PMID:18940186

  6. The Origin, Development and Molecular Diversity of Rodent Olfactory Bulb Glutamatergic Neurons Distinguished by Expression of Transcription Factor NeuroD1

    PubMed Central

    Roybon, Laurent; Mastracci, Teresa L.; Li, Joyce; Stott, Simon R. W.; Leiter, Andrew B.; Sussel, Lori; Brundin, Patrik; Li, Jia-Yi

    2015-01-01

    Production of olfactory bulb neurons occurs continuously in the rodent brain. Little is known, however, about cellular diversity in the glutamatergic neuron subpopulation. In the central nervous system, the basic helix-loop-helix transcription factor NeuroD1 (ND1) is commonly associated with glutamatergic neuron development. In this study, we utilized ND1 to identify the different subpopulations of olfactory bulb glutamategic neurons and their progenitors, both in the embryo and postnatally. Using knock-in mice, transgenic mice and retroviral transgene delivery, we demonstrate the existence of several different populations of glutamatergic olfactory bulb neurons, the progenitors of which are ND1+ and ND1- lineage-restricted, and are temporally and regionally separated. We show that the first olfactory bulb glutamatergic neurons produced – the mitral cells – can be divided into molecularly diverse subpopulations. Our findings illustrate the complexity of neuronal diversity in the olfactory bulb and that seemingly homogenous neuronal populations can consist of multiple subpopulations with unique molecular signatures of transcription factors and expressing neuronal subtype-specific markers. PMID:26030886

  7. p21 and Notch signalings in the persistently altered vagina induced by neonatal diethylstilbestrol exposure in mice.

    PubMed

    Nakamura, Takeshi; Miyagawa, Shinichi; Katsu, Yoshinao; Mizutani, Takeshi; Sato, Tomomi; Takeuchi, Takashi; Iguchi, Taisen; Ohta, Yasuhiko

    2012-12-01

    Female reproductive organs show organ-specific morphological changes during estrous cycles. Perinatal exposure to natural and synthetic estrogens including diethylstilbestrol (DES) or estrogenic chemicals induces estrogen-independent persistent proliferation of vaginal epithelium in mice. To understand the underlying mechanism of the estrogen-independent persistent vaginal changes induced by perinatal DES exposure, we examined global gene expressions in the vaginae of ovariectomized adult mice exposed neonatally to DES using a microarray. The cell cycle-related gene, p21, a cyclin-dependent kinase inhibitor, showed upregulation in the vagina, and p21 protein was localized in the basal layer of the vaginal epithelium in mice exposed neonatally to DES and an estrogen receptor α agonist, propyl pyrazole triol (PPT). The expressions of Notch receptors and Notch ligands were unchanged; however, the mRNAs of hairy-related basic helix-loop-helix (bHLH) transcription factor genes, Hes1, Hey1 and Heyl were persistently downregulated in the vagina, indicating estrogen-independent epithelial cell proliferation in mice exposed neonatally to DES and PPT. PMID:22850433

  8. Structural Basis for LMO2-Driven Recruitment of the SCL:E47bHLH Heterodimer to Hematopoietic-Specific Transcriptional Targets

    PubMed Central

    El Omari, Kamel; Hoosdally, Sarah J.; Tuladhar, Kapil; Karia, Dimple; Hall-Ponselé, Elisa; Platonova, Olga; Vyas, Paresh; Patient, Roger; Porcher, Catherine; Mancini, Erika J.

    2013-01-01

    Summary Cell fate is governed by combinatorial actions of transcriptional regulators assembling into multiprotein complexes. However, the molecular details of how these complexes form are poorly understood. One such complex, which contains the basic-helix-loop-helix heterodimer SCL:E47 and bridging proteins LMO2:LDB1, critically regulates hematopoiesis and induces T cell leukemia. Here, we report the crystal structure of (SCL:E47)bHLH:LMO2:LDB1LID bound to DNA, providing a molecular account of the network of interactions assembling this complex. This reveals an unexpected role for LMO2. Upon binding to SCL, LMO2 induces new hydrogen bonds in SCL:E47, thereby strengthening heterodimer formation. This imposes a rotation movement onto E47 that weakens the heterodimer:DNA interaction, shifting the main DNA-binding activity onto additional protein partners. Along with biochemical analyses, this illustrates, at an atomic level, how hematopoietic-specific SCL sequesters ubiquitous E47 and associated cofactors and supports SCL’s reported DNA-binding-independent functions. Importantly, this work will drive the design of small molecules inhibiting leukemogenic processes. PMID:23831025

  9. Stomatal Development in Arabidopsis

    PubMed Central

    Pillitteri, Lynn Jo; Dong, Juan

    2013-01-01

    Stomata consist of two guard cells that function as turgor-operated valves that regulate gas exchange in plants. In Arabidopsis, a dedicated cell lineage is initiated and undergoes a series of cell divisions and cell-state transitions to produce a stoma. A set of basic helix-loop-helix (bHLH) transcription factors regulates the transition and differentiation events through the lineage, while the placement of stomata relative to each other is controlled by intercellular signaling via peptide ligands, transmembrane receptors, and mitogen-activated protein kinase (MAPK) modules. Some genes involved in regulating stomatal differentiation or density are also involved in hormonal and environmental stress responses, which may provide a link between modulation of stomatal development or function in response to changes in the environment. Premitotic polarlylocalized proteins provide an added layer of regulation, which can be addressed more thoroughly with the identification of additional proteins in this pathway. Linking the networks that control stomatal development promises to bring advances to our understanding of signal transduction, cell polarity, and cell-fate specification in plants. PMID:23864836

  10. PHYTOCHROME INTERACTING FACTOR3 associates with the histone deacetylase HDA15 in repression of chlorophyll biosynthesis and photosynthesis in etiolated Arabidopsis seedlings.

    PubMed

    Liu, Xuncheng; Chen, Chia-Yang; Wang, Ko-Ching; Luo, Ming; Tai, Ready; Yuan, Lianyu; Zhao, Minglei; Yang, Songguang; Tian, Gang; Cui, Yuhai; Hsieh, Hsu-Liang; Wu, Keqiang

    2013-04-01

    PHYTOCHROME INTERACTING FACTOR3 (PIF3) is a key basic helix-loop-helix transcription factor of Arabidopsis thaliana that negatively regulates light responses, repressing chlorophyll biosynthesis, photosynthesis, and photomorphogenesis in the dark. However, the mechanism for the PIF3-mediated transcription regulation remains largely unknown. In this study, we found that the REDUCED POTASSIUM DEPENDENCY3/HISTONE DEACETYLASE1-type histone deacetylase HDA15 directly interacted with PIF3 in vivo and in vitro. Genome-wide transcriptome analysis revealed that HDA15 acts mainly as a transcriptional repressor and negatively regulates chlorophyll biosynthesis and photosynthesis gene expression in etiolated seedlings. HDA15 and PIF3 cotarget to the genes involved in chlorophyll biosynthesis and photosynthesis in the dark and repress gene expression by decreasing the acetylation levels and RNA Polymerase II-associated transcription. The binding of HDA15 to the target genes depends on the presence of PIF3. In addition, PIF3 and HDA15 are dissociated from the target genes upon exposure to red light. Taken together, our results indicate that PIF3 associates with HDA15 to repress chlorophyll biosynthetic and photosynthetic genes in etiolated seedlings. PMID:23548744

  11. PIF1 directly and indirectly regulates chlorophyll biosynthesis to optimize the greening process in Arabidopsis.

    PubMed

    Moon, Jennifer; Zhu, Ling; Shen, Hui; Huq, Enamul

    2008-07-01

    Plants depend on light signals to modulate many aspects of their development and optimize their photosynthetic capacity. Phytochromes (phys), a family of photoreceptors, initiate a signal transduction pathway that alters expression of a large number of genes to induce these responses. Recently, phyA and phyB were shown to bind members of a basic helix-loop-helix family of transcription factors called phy-interacting factors (PIFs). PIF1 negatively regulates chlorophyll biosynthesis and seed germination in the dark, and light-induced degradation of PIF1 relieves this negative regulation to promote photomorphogenesis. Here, we report that PIF1 regulates expression of a discrete set of genes in the dark, including protochlorophyllide oxidoreductase (POR), ferrochelatase (FeChII), and heme oxygenase (HO3), which are involved in controlling the chlorophyll biosynthetic pathway. Using ChIP and DNA gel-shift assays, we demonstrate that PIF1 directly binds to a G-box (CACGTG) DNA sequence element present in the PORC promoter. Moreover, in transient assays, PIF1 activates transcription of PORC in a G-box-dependent manner. These data strongly suggest that PIF1 directly and indirectly regulates key genes involved in chlorophyll biosynthesis to optimize the greening process in Arabidopsis. PMID:18591656

  12. Phytochromes promote seedling light responses by inhibiting four negatively-acting phytochrome-interacting factors.

    PubMed

    Shin, Jieun; Kim, Keunhwa; Kang, Hyojin; Zulfugarov, Ismayil S; Bae, Gabyong; Lee, Choon-Hwan; Lee, Doheon; Choi, Giltsu

    2009-05-01

    PIF3 is a phytochrome-interacting basic helix-loop-helix transcription factor that negatively regulates light responses, including hypocotyl elongation, cotyledon opening, and hypocotyl negative gravitropism. However, the role of PIF3 in chlorophyll biosynthesis has not been clearly defined. Here, we show that PIF3 also negatively regulates chlorophyll biosynthesis by repressing biosynthetic genes in the dark. Consistent with the gene expression patterns, the etiolated pif3 mutant accumulated a higher amount of protochlorophyllide and was bleached severely when transferred into light. The photobleaching phenotype of pif3 could be suppressed by the gun5 mutation and mimicked by overexpression of GUN5. When 4 negative phytochrome-interacting protein genes (PIF1, PIF3, PIF4, and PIF5) were mutated, the resulting quadruple mutant seedlings displayed constitutive photomorphogenic phenotypes, including short hypocotyls, open cotyledons, and disrupted hypocotyl gravitropism in the dark. Microarray analysis further confirmed that the dark-grown quadruple mutant has a gene expression pattern similar to that of red light-grown WT. Together, our data indicate that 4 phytochrome-interacting proteins are required for skotomorphogenesis and phytochromes activate photomorphogenesis by inhibiting these factors. PMID:19380720

  13. The Arabidopsis floral homeotic proteins APETALA3 and PISTILLATA negatively regulate the BANQUO genes implicated in light signaling.

    PubMed

    Mara, Chloe D; Huang, Tengbo; Irish, Vivian F

    2010-03-01

    The Arabidopsis thaliana MADS box transcription factors APETALA3 (AP3) and PISTILLATA (PI) heterodimerize and are required to specify petal identity, yet many details of how this regulatory process is effected are unclear. We have identified three related genes, BHLH136/BANQUO1 (BNQ1), BHLH134/BANQUO2 (BNQ2), and BHLH161/BANQUO3 (BNQ3), as being directly and negatively regulated by AP3 and PI in petals. BNQ1, BNQ2, and BNQ3 encode products belonging to a family of atypical non-DNA binding basic helix-loop-helix (bHLH) proteins that heterodimerize with and negatively regulate bHLH transcription factors. We show that bnq3 mutants have pale-green sepals and carpels and decreased chlorophyll levels, suggesting that BNQ3 has a role in regulating light responses. The ap3 bnq3 double mutant displays pale second-whorl organs, supporting the hypothesis that BNQ3 is downstream of AP3. Consistent with a role in light response, we show that the BNQ gene products regulate the function of HFR1 (for LONG HYPOCOTYL IN FAR-RED1), which encodes a bHLH protein that regulates photomorphogenesis through modulating phytochrome and cryptochrome signaling. The BNQ genes also are required for appropriate regulation of flowering time. Our results suggest that petal identity is specified in part through downregulation of BNQ-dependent photomorphogenic and developmental signaling pathways. PMID:20305124

  14. Cryptochromes, phytochromes, and COP1 regulate light-controlled stomatal development in Arabidopsis.

    PubMed

    Kang, Chun-Ying; Lian, Hong-Li; Wang, Fang-Fang; Huang, Ji-Rong; Yang, Hong-Quan

    2009-09-01

    In Arabidopsis thaliana, the cryptochrome (CRY) blue light photoreceptors and the phytochrome (phy) red/far-red light photoreceptors mediate a variety of light responses. COP1, a RING motif-containing E3 ubiquitin ligase, acts as a key repressor of photomorphogenesis. Production of stomata, which mediate gas and water vapor exchange between plants and their environment, is regulated by light and involves phyB and COP1. Here, we show that, in the loss-of-function mutants of CRY and phyB, stomatal development is inhibited under blue and red light, respectively. In the loss-of-function mutant of phyA, stomata are barely developed under far-red light. Strikingly, in the loss-of-function mutant of either COP1 or YDA, a mitogen-activated protein kinase kinase kinase, mature stomata are developed constitutively and produced in clusters in both light and darkness. CRY, phyA, and phyB act additively to promote stomatal development. COP1 acts genetically downstream of CRY, phyA, and phyB and in parallel with the leucine-rich repeat receptor-like protein TOO MANY MOUTHS but upstream of YDA and the three basic helix-loop-helix proteins SPEECHLESS, MUTE, and FAMA, respectively. These findings suggest that light-controlled stomatal development is likely mediated through a crosstalk between the cryptochrome-phytochrome-COP1 signaling system and the mitogen-activated protein kinase signaling pathway. PMID:19794114

  15. A bHLH gene from Tamarix hispida improves abiotic stress tolerance by enhancing osmotic potential and decreasing reactive oxygen species accumulation.

    PubMed

    Ji, Xiaoyu; Nie, Xianguang; Liu, Yujia; Zheng, Lei; Zhao, Huimin; Zhang, Bing; Huo, Lin; Wang, Yucheng

    2016-02-01

    Basic helix-loop-helix (bHLH) leucine-zipper transcription factors play important roles in abiotic stress responses. However, their specific roles in abiotic stress tolerance are not fully known. Here, we functionally characterized a bHLH gene, ThbHLH1, from Tamarix hispida in abiotic stress tolerance. ThbHLH1 specifically binds to G-box motif with the sequence of 'CACGTG'. Transiently transfected T. hispida plantlets with transiently overexpressed ThbHLH1 and RNAi-silenced ThbHLH1 were generated for gain- and loss-of-function analysis. Transgenic Arabidopsis thaliana lines overexpressing ThbHLH1 were generated to confirm the gain- and loss-of-function analysis. Overexpression of ThbHLH1 significantly elevates glycine betaine and proline levels, increases Ca(2+) concentration and enhances peroxidase (POD) and superoxide dismutase (SOD) activities to decrease reactive oxygen species (ROS) accumulation. Additionally, ThbHLH1 regulates the expression of the genes including P5CS, BADH, CaM, POD and SOD, to activate the above physiological changes, and also induces the expression of stress tolerance-related genes LEAs and HSPs. These data suggest that ThbHLH1 induces the expression of stress tolerance-related genes to improve abiotic stress tolerance by increasing osmotic potential, improving ROS scavenging capability and enhancing second messenger in stress signaling cascades. PMID:26786541

  16. MicroRNA 146 (Mir146) modulates spermatogonial differentiation by retinoic acid in mice.

    PubMed

    Huszar, Jessica M; Payne, Christopher J

    2013-01-01

    Impaired biogenesis of microRNAs disrupts spermatogenesis and leads to infertility in male mice. Spermatogonial differentiation is a key step in spermatogenesis, yet the mechanisms that control this event remain poorly defined. In this study, we discovered microRNA 146 (Mir146) to be highly regulated during spermatogonial differentiation, a process dependent on retinoic acid (RA) signaling. Mir146 transcript levels were diminished nearly 180-fold in differentiating spermatogonia when compared with undifferentiated spermatogonia. Luciferase assays revealed the direct binding of Mir146 to the 3' untranslated region of the mediator complex subunit 1 (Med1), a coregulator of retinoid receptors (RARs and RXRs). Overexpression of Mir146 in cultured undifferentiated spermatogonia reduced Med1 transcript levels, as well as those of differentiation marker kit oncogene (Kit). MED1 protein was also diminished. Conversely, inhibition of Mir146 increased the levels of Kit. When undifferentiated spermatogonia were exposed to RA, Mir146 was downregulated along with a marker for undifferentiated germ cells, zinc finger and BTB domain containing 16 (Zbtb16; Plzf); Kit was upregulated. Overexpression of Mir146 in RA-treated spermatogonia inhibited the upregulation of Kit, stimulated by retinoic acid gene 8 (Stra8), and spermatogenesis- and oogenesis-specific basic helix-loop-helix 2 (Sohlh2). Inhibition of Mir146 in RA-treated spermatogonia greatly enhanced the upregulation of these genes. We conclude that Mir146 modulates the effects of RA on spermatogonial differentiation. PMID:23221399

  17. Prdm13 mediates the balance of inhibitory and excitatory neurons in somatosensory circuits

    PubMed Central

    Chang, Joshua C.; Meredith, David M.; Mayer, Paul R.; Borromeo, Mark D.; Lai, Helen C.; Ou, Yi-Hung; Johnson, Jane E.

    2013-01-01

    SUMMARY Generating a balanced network of inhibitory and excitatory neurons during development requires precise transcriptional control. In the dorsal spinal cord, Ptf1a, a basic helix-loop-helix (bHLH) transcription activator, maintains this delicate balance by inducing homeodomain (HD) transcription factors such as Pax2 to specify the inhibitory lineage, while suppressing HD factors such as Tlx1/3 that specify the excitatory lineage. We uncover the mechanism by which Ptf1a represses excitatory cell fate in the inhibitory lineage. We identify Prdm13 as a direct target of Ptf1a and reveal that Prdm13 actively represses excitatory cell fate by binding to regulatory sequences near the Tlx1 and Tlx3 genes to silence their expression. Prdm13 acts through multiple mechanisms including interactions with the bHLH factor Ascl1 to repress Ascl1 activation of Tlx3. Thus, Prdm13 is a key component of a highly coordinated transcriptional network that determines the balance of inhibitory versus excitatory neurons in the dorsal spinal cord. PMID:23639443

  18. A functional EXO1 promoter variant is associated with prolonged life expectancy in centenarians.

    PubMed

    Nebel, Almut; Flachsbart, Friederike; Till, Andreas; Caliebe, Amke; Blanché, Hélène; Arlt, Alexander; Häsler, Robert; Jacobs, Gunnar; Kleindorp, Rabea; Franke, Andre; Shen, Binghui; Nikolaus, Susanna; Krawczak, Michael; Rosenstiel, Philip; Schreiber, Stefan

    2009-10-01

    Human longevity is heritable with a genetic component of 25-32%. Variation in genes regulating the levels of somatic maintenance and DNA repair functions is thought to modulate the aging process and to contribute to survival at advanced age. We tested 92 non-synonymous SNPs in 49 DNA repair genes for a possible association with longevity in a sample of 395 German centenarians and 411 controls. The obtained association signal in exonuclease 1 (EXO1) was further investigated by fine mapping and mutation detection, leading to the identification of the functionally relevant SNP rs1776180. Our detailed analyses revealed that the C allele of this promoter SNP is significantly enriched in female centenarians. This finding replicated in 455 female French centenarians and 109 controls. The C allele leads to the loss of a binding site for the basic helix-loop-helix transcription factor E47, resulting in higher EXO1 expression. Thus, we have detected a hitherto undescribed role for E47 as a negative regulator of EXO1 transcription and a genetic variant in the EXO1 promoter that counteracts the E47-mediated repression of the gene. Given the survival advantage that is associated with the C allele of rs1776180, EXO1 can be considered a candidate for a novel longevity-enabling gene. PMID:19698732

  19. Failure to Target RANKL Signaling Through p38-MAPK Results in Defective Osteoclastogenesis in the Microphthalmia Cloudy-Eyed Mutant.

    PubMed

    Carey, Heather A; Bronisz, Agnieszka; Cabrera, Jennifer; Hildreth, Blake E; Cuitiño, Maria; Fu, Qi; Ahmad, Asrar; Toribio, Ramiro E; Ostrowski, Michael C; Sharma, Sudarshana M

    2016-03-01

    The Microphthalmia-associated transcription factor (MITF) is a basic helix-loop-helix leucine zipper family factor that is essential for terminal osteoclast differentiation. Previous work demonstrates that phosphorylation of MITF by p38 MAPK downstream of Receptor Activator of NFkB Ligand (RANKL) signaling is necessary for MITF activation in osteoclasts. The spontaneous Mitf cloudy eyed (ce) allele results in production of a truncated MITF protein that lacks the leucine zipper and C-terminal end. Here we show that the Mitf(ce) allele leads to a dense bone phenotype in neonatal mice due to defective osteoclast differentiation. In response to RANKL stimulation, in vitro osteoclast differentiation was impaired in myeloid precursors derived from neonatal or adult Mitf(ce/ce) mice. The loss of the leucine zipper domain in Mitf(ce/ce) mice does not interfere with the recruitment of MITF/PU.1 complexes to target promoters. Further, we have mapped the p38 MAPK docking site within the region deleted in Mitf(ce). This interaction is necessary for the phosphorylation of MITF by p38 MAPK. Site-directed mutations in the docking site interfered with the interaction between MITF and its co-factors FUS and BRG1. MITF-ce fails to recruit FUS and BRG1 to target genes, resulting in decreased expression of target genes and impaired osteoclast function. These results highlight the crucial role of signaling dependent MITF/p38 MAPK interactions in osteoclast differentiation. PMID:26218069

  20. MESP1 Mutations in Patients with Congenital Heart Defects.

    PubMed

    Werner, Petra; Latney, Brande; Deardorff, Matthew A; Goldmuntz, Elizabeth

    2016-03-01

    Identifying the genetic etiology of congenital heart disease (CHD) has been challenging despite being one of the most common congenital malformations in humans. We previously identified a microdeletion in a patient with a ventricular septal defect containing over 40 genes including MESP1 (mesoderm posterior basic helix-loop-helix transcription factor 1). Because of the importance of MESP1 as an early regulator of cardiac development in both in vivo and in vitro studies, we tested for MESP1 mutations in 647 patients with congenital conotruncal and related heart defects. We identified six rare, nonsynonymous variants not seen in ethnically matched controls and one likely race-specific nonsynonymous variant. Functional analyses revealed that three of these variants altered activation of transcription by MESP1. Two of the deleterious variants are located within the conserved HLH domain and thus impair the protein-protein interaction of MESP1 and E47. The third deleterious variant was a loss-of-function frameshift mutation. Our results suggest that pathologic variants in MESP1 may contribute to the development of CHD and that additional protein partners and downstream targets could likewise contribute to the wide range of causes for CHD. PMID:26694203

  1. NRPB3, the third largest subunit of RNA polymerase II, is essential for stomatal patterning and differentiation in Arabidopsis.

    PubMed

    Chen, Liang; Guan, Liping; Qian, Pingping; Xu, Fan; Wu, Zhongliang; Wu, Yujun; He, Kai; Gou, Xiaoping; Li, Jia; Hou, Suiwen

    2016-05-01

    Stomata are highly specialized epidermal structures that control transpiration and gas exchange between plants and the environment. Signal networks underlying stomatal development have been previously uncovered but much less is known about how signals involved in stomatal development are transmitted to RNA polymerase II (Pol II or RPB), which plays a central role in the transcription of mRNA coding genes. Here, we identify a partial loss-of-function mutation of the third largest subunit of nuclear DNA-dependent Pol II (NRPB3) that exhibits an increased number of stomatal lineage cells and paired stomata. Phenotypic and genetic analyses indicated that NRPB3 is not only required for correct stomatal patterning, but is also essential for stomatal differentiation. Protein-protein interaction assays showed that NRPB3 directly interacts with two basic helix-loop-helix (bHLH) transcription factors, FAMA and INDUCER OF CBF EXPRESSION1 (ICE1), indicating that NRPB3 serves as an acceptor for signals from transcription factors involved in stomatal development. Our findings highlight the surprisingly conserved activating mechanisms mediated by the third largest subunit of Pol II in eukaryotes. PMID:26989174

  2. The mesoderm specification factor twist in the life cycle of jellyfish.

    PubMed

    Spring, J; Yanze, N; Middel, A M; Stierwald, M; Gröger, H; Schmid, V

    2000-12-15

    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 until the myoepithelial cells of the larva differentiate and then again during medusa development. There, the gene is detected first when the myoepithelial cells of the polyp dedifferentiate to form the medusa bud and later Twist is found transiently in the entocodon, a mesoderm-like cell layer which differentiates into the smooth muscle and striated muscle of the bell. On the other hand, in later bud stages and the medusa, expression is seen where non-muscle tissues differentiate. Experimental analysis of in vitro transdifferentiation and regeneration demonstrates that Twist activity is not needed when isolated striated muscle regenerate medusa organs. Developmental roles of Twist are discussed with respect to early animal evolution from a common ancestor of cnidarians and bilaterians. PMID:11112336

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

    PubMed Central

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

    2012-01-01

    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

  4. Cis-9,trans-11-conjugated linoleic acid promotes neuronal differentiation through regulation of Hes6 mRNA and cell cycle in cultured neural stem cells.

    PubMed

    Okui, Toshiyuki; Hashimoto, Michio; Katakura, Masanori; Shido, Osamu

    2011-01-01

    Conjugated linoleic acids (CLAs) are positional and geometrical isomers of linoleic acid (LA). Cis-9,trans-11-CLA (CLA), the main isomer of CLAs in foods derived from ruminants, has several beneficial effects for humans and animals; however, its effects on the central nervous system are largely unknown. In this study, we investigated the effects of LA and CLA on neuronal differentiation of neural stem cells (NSCs). NSCs cultured with or without LA and CLA were assessed by immunofluorescence staining, mRNA measurement of basic helix-loop-helix transcription factors and cyclin-dependent kinase inhibitors by real-time PCR, BrdU incorporation analysis and flow cytometry analysis. In NSCs treated with CLA, the number of Tuj-1-positive cells (neurons) and the mRNA expression levels of Hes6, MAP2, p21(cip1) and p27(kip1) increased, while the proportion of S-phase cells decreased; compared with the control, no change was demonstrated in NSCs treated with LA. These results suggest that CLA promotes neuronal differentiation by increasing, in part, the expression of Hes6 mRNA and by activating p21(cip1) and p27(kip1) to arrest cell cycle. PMID:21723718

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

    NASA Technical Reports Server (NTRS)

    Fritzsch, Bernd

    2003-01-01

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

  6. Genetic interaction between Kit and Scl

    PubMed Central

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

    2013-01-01

    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

  7. Ribosomal protein S14 negatively regulates c-Myc activity.

    PubMed

    Zhou, Xiang; Hao, Qian; Liao, Jun-Ming; Liao, Peng; Lu, Hua

    2013-07-26

    The ribosomal gene RPS14 is associated with the cancer-prone 5q-syndrome, which is caused by an interstitial deletion of the long arm of human chromosome 5. Previously, we found that ribosomal protein S14 (RPS14) binds to and inactivates MDM2, consequently leading to p53-dependent cell-cycle arrest and growth inhibition. However, it remains elusive whether RPS14 regulates cell proliferation in a p53-independent manner. Here, we show that RPS14 interacts with the Myc homology box II (MBII) and the C-terminal basic helix-loop-helix leucine zipper (bHLH-LZ) domains of the oncoprotein c-Myc. Further, RPS14 inhibited c-Myc transcriptional activity by preventing the recruitment of c-Myc and its cofactor, TRRAP, to the target gene promoters, as thus suppressing c-Myc-induced cell proliferation. Also, siRNA-mediated RPS14 depletion elevated c-Myc transcriptional activity determined by its target gene, Nucleolin, expression. Interestingly, RPS14 depletion also resulted in the induction of c-Myc mRNA and subsequent protein levels. Consistent with this, RPS14 promoted c-Myc mRNA turnover through an Argonaute 2 (Ago2)- and microRNA-mediated pathway. Taken together, our study demonstrates that RPS14 negates c-Myc functions by directly inhibiting its transcriptional activity and mediating its mRNA degradation via miRNA. PMID:23775087

  8. Up-regulation of the Sirtuin 1 (Sirt1) and Peroxisome Proliferator-activated Receptor γ Coactivator-1α (PGC-1α) Genes in White Adipose Tissue of Id1 Protein-deficient Mice

    PubMed Central

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

    2014-01-01

    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 TNFα gene expression in white adipose tissue. Id1 deficiency also increased expression of Sirtuin 1 and peroxisome proliferator-activated receptor γ coactivator 1α, 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

  9. Genomic cloning and chromosomal localization of HRY, the human homolog to the Drosophila segmentation gene, hairy

    SciTech Connect

    Feder, J.N.; Jan, L.Y.; Jan, Y.N.; Li, L. )

    1994-03-01

    The Drosophila hairy gene encodes a basic helix- loop-helix protein that functions in at least two steps during Drosophila development: (1) during embryogenesis, when it partakes in the establishment of segments, and (2) during the larval stage, when it functions negatively in determining the pattern of sensory bristles on the adult fly. In the rat, a structurally homologous gene (RHL) behaves as an immediate-early gene in its response to growth factors and can, like that in Drosophila, suppress neuronal differentiation events. Here, the authors report the genomic cloning of the human hairy gene homolog (HRY). The coding region of the gene is contained within four exons. The predicted amino acid sequence reveals only four amino acid differences between the human and rat genes. Analysis of the DNA sequence 5[prime] to the coding region reveals a putatitve untranslated exon. To increase the value of the HRY gene as a genetic marker and to assess its potential involvement in genetic disorders, they sublocalized the locus to chromosome 3q28-q29 by fluorescence in situ hybridization. 34 refs., 4 figs., 1 tab.

  10. Synergistic interactions of lipids and myelin basic protein

    NASA Astrophysics Data System (ADS)

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

    2004-09-01

    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

  11. BasicODT

    Energy Science and Technology Software Center (ESTSC)

    2007-09-25

    BasicODT is a Monte Carlo simulation that numerically implements One-Dimensional Turbulence (ODT), a stochastic model of turbulent flow that was developed by the author of the code. This code is set up to simulate channel flow, which is the flow between two parallel flat walls driven by a fixed pressure gradient, with no-slip conditions at the walls. The code writes output files containing flow statistics gathered during the simulation. The code is accompanied by documentationmore » that explains how ODT modeling principles are numerically implemented within the code. The code and documentation are intended as an introduction to ODT for use as a learning tool for people who are unfamiliar with the model and its numerical implementation. ODT is fully described in published literature.« less

  12. Atomic Basic Blocks

    NASA Astrophysics Data System (ADS)

    Scheler, Fabian; Mitzlaff, Martin; Schröder-Preikschat, Wolfgang

    Die Entscheidung, einen zeit- bzw. ereignisgesteuerten Ansatz für ein Echtzeitsystem zu verwenden, ist schwierig und sehr weitreichend. Weitreichend vor allem deshalb, weil diese beiden Ansätze mit äußerst unterschiedlichen Kontrollflussabstraktionen verknüpft sind, die eine spätere Migration zum anderen Paradigma sehr schwer oder gar unmöglich machen. Wir schlagen daher die Verwendung einer Zwischendarstellung vor, die unabhängig von der jeweils verwendeten Kontrollflussabstraktion ist. Für diesen Zweck verwenden wir auf Basisblöcken basierende Atomic Basic Blocks (ABB) und bauen darauf ein Werkzeug, den Real-Time Systems Compiler (RTSC) auf, der die Migration zwischen zeit- und ereignisgesteuerten Systemen unterstützt.

  13. Basic properties and variability

    NASA Technical Reports Server (NTRS)

    Querci, Francois R.

    1987-01-01

    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.

  14. Basic memory module

    NASA Technical Reports Server (NTRS)

    Tietze, F. C.

    1974-01-01

    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.

  15. Basic MHD Turbulence

    NASA Astrophysics Data System (ADS)

    Beresnyak, Andrey

    2013-01-01

    Astrophysical fluids are conductive, magnetized and turbulent. This entails a variety of phenomena, two most basic of which is the dynamo and the energy cascade. Very well known empirically in hydrodynamics so called "zeroth law of turbulence" states that even if viscosity goes to zero, energy dissipation does not, but goes to a constant. It turns out that in MHD not only this still holds true, but another basic law, which I call "zeroth law of dynamo", is valid, namely that if Reynolds numbers are sufficiently high and magnetic energy is low, the latter will grow at a constant rate, which is a fraction of the total dissipation rate. Another point of interest for an astrophysicist is the properties of MHD cascade in the inertial range. I will argue that both theory and numerics favor Kolmogorov -5/3 slope and not -3/2 slope that was reported earlier. The most challenging problem is so-called imbalanced, or cross-helical case which appear whenever there is a localized source of perturbations, such as the Sun for the solar wind turbulence or the central engine in AGN jets. The standard Goldreich-Sridhar model does not apply in this case and it eluded theoretical description for a long time. The keys to understand energy cascades in the imbalanced case are the anisotropies of the Elsasser fields which turn out to be different. I will show the results of one of the highest resolution simulations ever performed, which were very helpful in discriminating between various viable models of MHD turbulence.

  16. [Basic research in pulmonology].

    PubMed

    Gea, Joaquim

    2008-11-01

    This is a review of the articles dealing with basic science published in recent issues of Archivos de Bronconeumología. Of particular interest with regard to chronic obstructive pulmonary disease were an article on extrapulmonary inflammation and oxidative stress and another on bronchial remodeling. The articles relating to asthma included a review on the use of drugs that block free immunoglobulin-E and an article about the contribution of experimental models to our knowledge of this disease. Two of the most interesting articles on the topic of lung cancer dealt with gene therapy and resistance to chemotherapy. Also notable were 2 studies that investigated ischemia-reperfusion injury. One evaluated tissue resistance to injury while the other analyzed the role played by interleukin-8 in this process. On the topic of pulmonary fibrosis, an article focused on potential biomarkers of progression and prognosis; others dealt with the contribution of experimental models to our understanding of this disorder and the fibrogenic role of transforming growth factor b. In the context of both sleep apnea syndrome and pulmonary infection, studies investigating the role of oxidative stress were published. Finally, 2 studies analyzed the diagnosis and treatment of tuberculosis and other pulmonary infections. PMID:19007569

  17. Basic teaching in microsurgery.

    PubMed

    Mikó, I; Bráth, E; Furka, I

    2001-01-01

    We summarize our 15 years of educational experience in the field of teaching microsurgery. The students can be divided into three groups: (1) medical students, (2) researchers, (3) medical doctors and specialists. Characteristics of our method include the following: activity, synchronism, video-assistance, self-controlling, individualization, analysis. The Furka microsurgical educational method, named after one of the authors, is 20 hours long (five 4-hour sessions). The first lesson allows students to become acquainted with the microsurgical instruments. The next lesson consists of learning the probe of layer-feeling. The third lesson is to learn how to produce stitches under the microscope. The fourth lesson includes arterial anastomosis preparation on fresh arterial pieces of animal origin. The fifth lesson means a quality change from previous classes, as practice is performed on living animals, generally rats. The teaching of microsurgical basics requires both patience and empathy. The teaching process is most successful if one teacher deals with a maximum of two students. PMID:11494375

  18. Back to basics

    NASA Astrophysics Data System (ADS)

    Carlowicz, Michael

    In an effort to educate the public about the long road from obscure experiment to life-changing discovery, the National Academy of Sciences (NAS) has been enlisting prominent researchers, science writers, and scientific organizations such as the AGU. More than two years in development, the NAS basic science initiative “Beyond Discovery: The Path From Research to Human Benefits” is an attempt to translate peer-review-quality science papers into general-interest science articles and booklets.As conceived by NAS vice-president Jack Halpern and a host of representatives from the scientific community, the Beyond Discovery initiative will “develop case studies that identify and trace the origins of important technological and medical advances.” These case studies will be written by scientists in a style publishable in a journal such as the Proceedings of the National Academy of Science. The articles are intended to be understandable to educators, college students, and the scientifically literate public. The case studies then will be further distilled by science writers into articles for a wider audience of policy makers and the general public.

  19. Acute Pancreatitis (Beyond the Basics)

    MedlinePlus

    ... pancreatitis. (See "Patient information: Gallstones (Beyond the Basics)" .) Alcoholic pancreatitis — Alcohol is a common cause of acute pancreatitis. Alcoholic pancreatitis is more common in individuals who have ...

  20. Japanese Basic Course: Exercise Book.

    ERIC Educational Resources Information Center

    Defense Language Inst., Washington, DC.

    This exercise book, prepared for use after Lesson 121 of the Defense Language Institute Basic Course in Japanese, provides for instruction in the use of Kanji dictionaries, familiarizes students with useful phrases and expressions that are not included in the Basic Course, and allows for greater variety in the classroom. The ten lessons, in the…

  1. Basic Skills. NIACE Briefing Sheet.

    ERIC Educational Resources Information Center

    National Inst. of Adult Continuing Education, Leicester (England).

    Skills For Life, since 2001 the United Kingdom's national adult basic skills strategy, aims to improve literacy, numeracy, or English for speakers of other languages (ESOL) skills among people over the age of 16. Basic skills programs may be full- or part-time and are delivered in colleges, community venues, neighborhood learning centers, adult…

  2. Chinese-Cantonese Basic Course.

    ERIC Educational Resources Information Center

    Defense Language Inst., Washington, DC.

    This nine-volume basic course in Cantonese Chinese is designed for 47 weeks of intense audiolingual instruction. The first book of the series introduces the pronunciation, with emphasis on the tone system, and the basic aspects of the grammar. Also introduced in this volume is the romanization system used in this series (the U.S. Army Language…

  3. Children and Their Basic Needs.

    ERIC Educational Resources Information Center

    Prince, Debra Lindsey; Howard, Esther M.

    2002-01-01

    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)

  4. Are Basic Writers Cognitively Deficient?

    ERIC Educational Resources Information Center

    Martinez, Joseph G. R.; Martinez, Nancy C.

    Researchers of writing ability have often applied the developmental schemes of William Perry, Lev Vygotsky, and Jean Piaget in describing basic writers. As a result, some researchers have concluded that basic writers think well below the formal-operations or true concept-formation stage of cognitive development. To investigate the theory that…

  5. Basic Skills: Dealing with Deficiencies.

    ERIC Educational Resources Information Center

    New Mexico State Univ., Las Cruces.

    Research findings on college instruction and basic skills deficiencies are discussed in 12 papers from the first Regional Conference on University Teaching. Titles and authors are as follows: "Basic Skills: Dealing with Deficiencies" (Susanne D. Roueche, with responses by Gary B. Donart, Betty Harris, and James Nordyke); "Is Higher Education an…

  6. Testing in Adult Basic Education.

    ERIC Educational Resources Information Center

    Ehringhaus, Carolyn

    1991-01-01

    Responses from 427 adult basic education teachers (51 percent response) indicated that (1) 84.8 percent use tests for placement; (2) the Tests of Adult Basic Education are overwhelmingly the most frequently used; and (3) 77.7 percent find their testing practices effective, although informal observation and assessment received the highest ranking.…

  7. The California Basic Skills Initiative

    ERIC Educational Resources Information Center

    Illowsky, Barbara

    2008-01-01

    This article describes the evolution and implementation of the California Basic Skills Initiative (CA BSI), a statewide effort to address ongoing basic skills and ESL needs of community college students and of all campus faculty, administrators, and staff who support these students. CA BSI strategies include assisting every college in assessing…

  8. IMMUNOHISTOCHEMICAL DOUBLE-STAINING FOR AH RECEPTOR AND ARNT IN HUMAN EMBRYONIC PALATAL SHELVES

    EPA Science Inventory

    The aryl hydrocarbon receptor (AhR) and the AhR nuclear translocation protein (ARNT) are helix-loop-helix (HLH) proteins involved in transcriptional regulation. olycyclic aromatic halogenated chemicals, of which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the most potent, bind ...

  9. PEROXISOME PROLIFERATOR-ACTIVATED RECEPTORα (PPARα) AGONISTS DIFFERENTIALLY REGULATE INHIBITOR OF DNA BINDING (ID2) EXPRESSION IN RODENTS AND HUMAN CELLS

    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,...

  10. PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR? (PPAR?) AGONISTS DIFFERENTIALLY REGULATE INHIBITOR OF DNA BINDING (ID2) EXPRESSION IN RODENTS AND HUMAN CELLS

    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,...

  11. The basic aerodynamics of floatation

    SciTech Connect

    Davies, M.J.; Wood, D.H.

    1983-09-01

    The original derivation of the basic theory governing the aerodynamics of both hovercraft and modern floatation ovens, requires the validity of some extremely crude assumptions. However, the basic theory is surprisingly accurate. It is shown that this accuracy occurs because the final expression of the basic theory can be derived by approximating the full Navier-Stokes equations in a manner that clearly shows the limitations of the theory. These limitations are used in discussing the relatively small discrepancies between the theory and experiment, which may not be significant for practical purposes.

  12. About Alzheimer's Disease: Alzheimer's Basics

    MedlinePlus

    ... National Alzheimer's Project Act (NAPA) About ADEAR About Alzheimer's Disease: Alzheimer's Basics What is Alzheimer's disease? What happens to ... with Alzheimer's disease? What is dementia? What is Alzheimer's disease? Alzheimer’s disease is an irreversible, progressive brain ...

  13. Plants, Animals and Basic Skills.

    ERIC Educational Resources Information Center

    Pheasant, Robert

    2000-01-01

    Countrystart is a class in which students work with plants and animals, providing numerous opportunities to integrate basic skills teaching. The practical subject area becomes the vehicle to develop other skills needed by students. (JOW)

  14. Basics.

    ERIC Educational Resources Information Center

    Instructor, 1982

    1982-01-01

    Recommended activities include: (1) etymology exercises for elementary school students; (2) a search for information about Alexander the Great; (3) monthly inspections of the school yard to observe environmental changes; and (4) an art history unit on Cro-Magnon cave drawings. An interdisciplinary unit on transportation is included. (PP)

  15. E-Basics: Online Basic Training in Program Evaluation

    ERIC Educational Resources Information Center

    Silliman, Ben

    2016-01-01

    E-Basics is an online training in program evaluation concepts and skills designed for youth development professionals, especially those working in nonformal science education. Ten hours of online training in seven modules is designed to prepare participants for mentoring and applied practice, mastery, and/or team leadership in program evaluation.…

  16. Arabic Basic Course: Basic Dialogues for Airport Facilities.

    ERIC Educational Resources Information Center

    Defense Language Inst., Washington, DC.

    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…

  17. Basic Operational Robotics Instructional System

    NASA Technical Reports Server (NTRS)

    Todd, Brian Keith; Fischer, James; Falgout, Jane; Schweers, John

    2013-01-01

    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.

  18. The basic aerodynamics of floatation

    NASA Astrophysics Data System (ADS)

    Davies, M. J.; Wood, D. H.

    1983-09-01

    It is pointed out that the basic aerodynamics of modern floatation ovens, in which the continuous, freshly painted metal strip is floated, dried, and cured, is the two-dimensional analog of that of hovercraft. The basic theory for the static lift considered in connection with the study of hovercraft has had spectacular success in describing the experimental results. This appears surprising in view of the crudity of the theory. The present investigation represents an attempt to explore the reasons for this success. An outline of the basic theory is presented and an approach is shown for deriving the resulting expressions for the lift from the full Navier-Stokes equations in a manner that clearly indicates the limitations on the validity of the expressions. Attention is given to the generally good agreement between the theory and the axisymmetric (about the centerline) results reported by Jaumotte and Kiedrzynski (1965).

  19. Basic research for environmental restoration

    SciTech Connect

    Not Available

    1990-12-01

    The Department of Energy (DOE) is in the midst of a major environmental restoration effort to reduce the health and environmental risks resulting from past waste management and disposal practices at DOE sites. This report describes research needs in environmental restoration and complements a previously published document, DOE/ER-0419, Evaluation of Mid-to-Long Term Basic Research for Environmental Restoration. Basic research needs have been grouped into five major categories patterned after those identified in DOE/ER-0419: (1) environmental transport and transformations; (2) advanced sampling, characterization, and monitoring methods; (3) new remediation technologies; (4) performance assessment; and (5) health and environmental effects. In addition to basic research, this document deals with education and training needs for environmental restoration. 2 figs., 6 tabs.

  20. Basic Communication Course Annual. Volume 2.

    ERIC Educational Resources Information Center

    Hugenberg, Lawrence W., Ed.

    This annual collection contains essays relating to instruction in the basic communication course, grading in the basic communication course, evaluating the basic communication course, and the "state" of the basic communication course. Papers in the collection include: "The Future of the Basic Course" (Judy C. Pearson and Paul Nelson);…