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1

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

Microsoft Academic Search

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

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

2007-01-01

2

A natural classification of the basic helix-loop-helix class of transcription factors  

PubMed Central

A natural (evolutionary) classification is provided for 242 basic helix–loop–helix (bHLH) motif-containing proteins. Phylogenetic analyses of amino acid sequences describe the patterns of evolutionary change within the motif and delimit evolutionary lineages. These evolutionary lineages represent well known functional groups of proteins and can be further arranged into five groups based on binding to DNA at the hexanucleotide E-box, the amino acid patterns in other components of the motif, and the presence/absence of a leucine zipper. The hypothesized ancestral amino acid sequence for the bHLH transcription factor family is given together with the ancestral sequences of the subgroups. It is suggested that bHLH proteins containing a leucine zipper are not a natural, monophyletic group. PMID:9144210

Atchley, William R.; Fitch, Walter M.

1997-01-01

3

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

E-print Network

of anthocyanin pigmentation genes in flowers. We cloned the full-length coding region from 2 basic helix-loop-helix transcription factors from several species of Ipomoea with diverse flower colors and determined the selective previously characterized plant transcription factors. Moreover, codon models of substitution rates and models

Oregon, University of

4

Possible roles of basic helix-loop-helix transcription factors in adaptation to drought.  

PubMed

Water deficiency decreases plant growth and productivity. Several mechanisms are activated in response to dehydration that allows plants to cope with stress, including factors controlling stomatal aperture and ramified root system development. In addition, ABA metabolism is also implicated in the regulation of drought responses. The basic helix-loop-helix (bHLH) proteins, a large family of conserved transcription factors that regulates many cellular processes in eukaryotic organisms, are also involved in several responses that are important for plants to cope with drought stress. This review discusses distinct mechanisms related to drought-adaptive responses, especially the possible involvement of the bHLH transcription factors such as MUTE, implicated in stomatal development; RD29, an ABA-responsive gene; EGL3 and GL3, involved in thichome and root hair development; and SPT, which play roles in repressing leaf expansion. Transcription factors are potential targets for new strategies to increase the tolerance of cultivars to drought stress. Recognition of gene regulatory networks in crops is challenging, and the manipulation of bHLH genes as well as components that mediate bHLH transcription factor responses in different pathways could be essential to achieve abiotic stress tolerance in plants through genetic manipulation. PMID:24767109

Castilhos, Graciela; Lazzarotto, Fernanda; Spagnolo-Fonini, Leila; Bodanese-Zanettini, Maria Helena; Margis-Pinheiro, Márcia

2014-06-01

5

A Genome-Wide Survey on Basic Helix-Loop-Helix Transcription Factors in Giant Panda  

PubMed Central

The giant panda (Ailuropoda melanoleuca) is a critically endangered mammalian species. Studies on functions of regulatory proteins involved in developmental processes would facilitate understanding of specific behavior in giant panda. The basic helix-loop-helix (bHLH) proteins play essential roles in a wide range of developmental processes in higher organisms. bHLH family members have been identified in over 20 organisms, including fruit fly, zebrafish, mouse and human. Our present study identified 107 bHLH family members being encoded in giant panda genome. Phylogenetic analyses revealed that they belong to 44 bHLH families with 46, 25, 15, 4, 11 and 3 members in group A, B, C, D, E and F, respectively, while the remaining 3 members were assigned into “orphan”. Compared to mouse, the giant panda does not encode seven bHLH proteins namely Beta3a, Mesp2, Sclerax, S-Myc, Hes5 (or Hes6), EBF4 and Orphan 1. These results provide useful background information for future studies on structure and function of bHLH proteins in the regulation of giant panda development. PMID:22096504

Dang, Chunwang; Wang, Yong; Zhang, Debao; Yao, Qin; Chen, Keping

2011-01-01

6

Phylogenetic analysis of the human basic helix-loop-helix proteins  

PubMed Central

Background The basic helix-loop-helix (bHLH) proteins are a large and complex multigene family of transcription factors with important roles in animal development, including that of fruitflies, nematodes and vertebrates. The identification of orthologous relationships among the bHLH genes from these widely divergent taxa allows reconstruction of the putative complement of bHLH genes present in the genome of their last common ancestor. Results We identified 39 different bHLH genes in the worm Caenorhabditis elegans, 58 in the fly Drosophila melanogaster and 125 in human (Homo sapiens). We defined 44 orthologous families that include most of these bHLH genes. Of these, 43 include both human and fly and/or worm genes, indicating that genes from these families were already present in the last common ancestor of worm, fly and human. Only two families contain both yeast and animal genes, and no family contains both plant and animal bHLH genes. We suggest that the diversification of bHLH genes is directly linked to the acquisition of multicellularity, and that important diversification of the bHLH repertoire occurred independently in animals and plants. Conclusions As the last common ancestor of worm, fly and human is also that of all bilaterian animals, our analysis indicates that this ancient ancestor must have possessed at least 43 different types of bHLH, highlighting its genomic complexity. PMID:12093377

2002-01-01

7

Gene replacement strategies to test the functional redundancy of basic helix-loop-helix transcription factor.  

PubMed

Basic helix-loop-helix (bHLH) transcription factors control developmental decisions for a wide range of embryonic cell types. Hand1 and Hand2 are closely related bHLH proteins that control cardiac, craniofacial, and limb development. Within the developing heart, Hand1 expression becomes restricted predominantly to the left ventricle, whereas Hand2 becomes restricted predominantly to the left ventricle, for which findings have shown each Hand factor to be necessary for normal chamber formation. Forced overexpression of Hand1 throughout the early developing heart induces abnormal interventricular septal development, with resulting pathogenesis of congenital heart defects. To investigate the potential transcriptional mechanisms involved in heart morphogenesis by Hand2, this study used a replacement targeting approach to knock Hand2 into the Hand1 locus and ectopically express one copy of Hand2 within the endogenous Hand1 expression domain in the developing hearts of transgenic mice. The findings show that high-percentage Hand1 ( Hand2 ) chimeras die at birth and exhibit a range of congenital heart defects. These findings suggest that Hand factors may act via unique transcriptional mechanisms mediated by bHLH factor partner choice, supporting the notion that alterations of Hand factor stoichiometry may be as deleterious to normal heart morphogenesis as Hand factor loss of function. PMID:20155416

Firulli, Anthony B; Firulli, Beth A; Wang, Jian; Rogers, Rhonda H; Conway, Simon J

2010-04-01

8

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

Microsoft Academic Search

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

Qiao Zhou; Songli Wang; David J. Anderson

2000-01-01

9

Phylogenetic analyses of vector mosquito basic helix-loop-helix transcription factors.  

PubMed

Basic helix-loop-helix (bHLH) transcription factors play critical roles in the regulation of a wide range of developmental processes in higher organisms and have been identified in more than 20 organisms. Mosquitoes are important vectors of certain human diseases. In this study, Aedes aegypti, Anopheles gambiae str. PEST and Culex quinquefasciatus genomes were found to encode 55, 55 and 57 bHLH genes, respectively. Further phylogenetic analyses and OrthoDB and Kyoto encyclopedia of genes and genomes orthology database searches led us to define orthology for all the identified mosquito bHLHs successfully. This provides useful information with which to update annotations to 40 Ae.?aegypti, 55 An.?gambiae and 38 C.?quinquefasciatus?bHLH genes in VectorBase. The mosquito lineage has more bHLH genes in the Atonal, neurogenin (Ngn) and Hes-related with YRPW motif (Hey) families than do other insect species, suggesting that mosquitoes have evolved to be more sensitive to vibration, light and chemicals. Mosquito bHLH genes generally have higher evolutionary rates than other insect species. However, no pervasive positive selection occurred in the evolution of insect bHLH genes. Only episodic positive selection was found to affect evolution of bHLH genes in 11 families. Besides, coding regions of several Ae.?aegypti?bHLH motifs have unusually long introns in which multiple copies of transposable elements have been identified. These data provide a solid basis for further studies on structures and functions of bHLH proteins in the regulation of mosquito development and for prevention and control of mosquito-mediated human diseases. PMID:23906262

Zhang, D B; Wang, Y; Liu, A K; Wang, X H; Dang, C W; Yao, Q; Chen, K P

2013-10-01

10

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

PubMed Central

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

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

1993-01-01

11

Basic helix-loop-helix transcription factor Tcfl5 interacts with the Calmegin gene promoter in mouse spermatogenesis.  

PubMed

In mouse spermatogenesis, differentiating germ line cells initiate expression of specific genes at subsequent developmental steps. The Calmegin (Clgn) gene is first expressed in meiotic prophase, in primary spermatocytes, and encodes a protein that acts as a chaperone. To identify testis-specific transcription factors that control expression of the Clgn gene in spermatogenesis, we performed a yeast one-hybrid screening with a Clgn promoter sequence as bait DNA. This screening resulted in the identification of mouse Tcfl5 as a candidate Clgn promoter-binding protein. Tcfl5 is a member of the basic helix-loop-helix (bHLH) family of transcription factors, and mouse Tcfl5 shows 83% amino acid sequence identity with human TCFL5. Gel-shift and yeast one-hybrid experiments showed that Tcfl5 interacts with a non-canonical CACGCG site that is present in the Clgn promoter. By using northern blot, RT-PCR and in situ hybridization, mouse Tcfl5 mRNA was detected only in testis, with the highest expression level in primary spermatocytes and round spermatids. The highest level of Tcfl5 protein was found in primary spermatocytes at the diplotene stage of meiotic prophase, where the protein colocalizes with transcriptionally active chromatin. PMID:15585666

Siep, Michel; Sleddens-Linkels, Esther; Mulders, Sabine; van Eenennaam, Hans; Wassenaar, Evelyne; Van Cappellen, Wiggert A; Hoogerbrugge, Jos; Grootegoed, J Anton; Baarends, Willy M

2004-01-01

12

Basic helix-loop-helix transcription factor Tcfl5 interacts with the Calmegin gene promoter in mouse spermatogenesis  

PubMed Central

In mouse spermatogenesis, differentiating germ line cells initiate expression of specific genes at subsequent developmental steps. The Calmegin (Clgn) gene is first expressed in meiotic prophase, in primary spermatocytes, and encodes a protein that acts as a chaperone. To identify testis-specific transcription factors that control expression of the Clgn gene in spermatogenesis, we performed a yeast one-hybrid screening with a Clgn promoter sequence as bait DNA. This screening resulted in the identification of mouse Tcfl5 as a candidate Clgn promoter-binding protein. Tcfl5 is a member of the basic helix–loop–helix (bHLH) family of transcription factors, and mouse Tcfl5 shows 83% amino acid sequence identity with human TCFL5. Gel-shift and yeast one-hybrid experiments showed that Tcfl5 interacts with a non-canonical CACGCG site that is present in the Clgn promoter. By using northern blot, RT–PCR and in situ hybridization, mouse Tcfl5 mRNA was detected only in testis, with the highest expression level in primary spermatocytes and round spermatids. The highest level of Tcfl5 protein was found in primary spermatocytes at the diplotene stage of meiotic prophase, where the protein colocalizes with transcriptionally active chromatin. PMID:15585666

Siep, Michel; Sleddens-Linkels, Esther; Mulders, Sabine; van Eenennaam, Hans; Wassenaar, Evelyne; Van Cappellen, Wiggert A.; Hoogerbrugge, Jos; Grootegoed, J. Anton; Baarends, Willy M.

2004-01-01

13

The basic helix-loop-helix transcription factor Mist1 functions as a transcriptional repressor of myoD.  

PubMed Central

A good model system to examine aspects of positive and negative transcriptional regulation is the muscle-specific regulatory factor, MyoD, which is a basic helix-loop-helix (bHLH) transcription factor. Although MyoD has the ability to induce skeletal muscle terminal differentiation in a variety of non-muscle cell types, MyoD activity itself is highly regulated through protein-protein interactions involving several different co-factors. Here we describe the characterization of a novel bHLH protein, Mist1, and how it influences MyoD function. We show that Mist1 accumulates in myogenic stem cells (myoblasts) and then decreases as myoblasts differentiate into myotubes. Mist1 functions as a negative regulator of MyoD activity, preventing muscle differentiation and the concomitant expression of muscle-specific genes. Mist1-induced inhibition occurs through a combination of mechanisms, including the formation of inactive MyoD-Mist1 heterodimers and occupancy of specific E-box target sites by Mist1 homodimers. Mist1 lacks a classic transcription activation domain and instead possesses an N-terminal repressor region capable of inhibiting heterologous activators. Thus, Mist1 may represent a new class of repressor molecules that play a role in controlling the transcriptional activity of MyoD, ensuring that expanding myoblast populations remain undifferentiated during early embryonic muscle formation. PMID:9482738

Lemercier, C; To, R Q; Carrasco, R A; Konieczny, S F

1998-01-01

14

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

PubMed Central

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

Chen, Deyu

2013-01-01

15

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

PubMed Central

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

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

2002-01-01

16

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

PubMed Central

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

Hallsson, Jon H; Haflidadottir, Benedikta S; Stivers, Chad; Odenwald, Ward; Arnheiter, Heinz; Pignoni, Francesca; Steingrimsson, Eirikur

2004-01-01

17

Target genes for OBP3, a Dof transcription factor, include novel basic helix-loop-helix domain proteins inducible by  

E-print Network

proteins inducible by salicylic acid Hong-Gu Kang1,y,z , Rhonda C. Foley2,z , Luis On� ate-Sa�nchez2 contributed equally to the paper. Summary Overexpression of a salicylic-acid (SA)-inducible Arabidopsis DNA helix-loop-helix, salicylic acid, jasmonic acid, AtDof3.6. Introduction Although there is considerable

Lin, Chentao

18

Gene Expression of Basic Helix-Loop-Helix Transcription Factor, SHARP2, Is Regulated by Gonadotropins in the Rat Ovary and MA10 Cells1  

Microsoft Academic Search

Basic helix-loop-helix (bHLH) proteins regulate transcrip- tion from the E box sequence (59-CANNTG-39) located in the regulatory region of most gene promoters. The rat enhancer of split- and hairy-related protein 2 (SHARP-2) is a member of the bHLH protein family. To analyze the possible role of SHARP-2 in the rat ovary, the regulation of the expression of the SHARP- 2

Kazuya Yamada; Hiroko Kawata; Tetsuya Mizutani; Takeshi Arima; Takashi Yazawa; Kaoru Matsuura; Zhangfei Shou; Toshio Sekiguchi; Miki Yoshino; Takashi Kajitani; Kaoru Miyamoto

19

Multiple Roles of Ligand in Transforming the Dioxin Receptor to an Active Basic Helix-Loop-Helix\\/PAS Transcription Factor Complex with the Nuclear Protein Arnt  

Microsoft Academic Search

The dioxin receptor is a ligand-activated transcription factor belonging to an emerging class of basic helix-loop-helix\\/PAS proteins which show interaction with the molecular chaperone hsp90 in their latent states and require heterodimerization with a general cofactor, Arnt, to form active DNA binding complexes. Upon binding of polycyclic aromatic hydrocarbons typified by dioxin, the dioxin receptor translocates from the cytoplasm to

MICHAEL J. LEES; MURRAY L. WHITELAW

1999-01-01

20

Interpretation of X Chromosome Dose at Sex-lethal Requires Non-E-Box Sites for the Basic Helix-Loop-Helix Proteins SISB and Daughterless  

Microsoft Academic Search

For Drosophila melanogaster flies, sexual fate is determined by the X chromosome number. The basic helix-loop-helix protein product of the X-linked sisterlessB (sisB or scute) gene is a key indicator of the X dose and functions to activate the switch gene Sex-lethal (Sxl) in female (XX), but not in male (XY), embryos. Zygotically expressed sisB and maternal daughterless (da) proteins

DUN YANG; HONG LU; YONG HONG; TIMOTHY M. JINKS; PATRICIA A. ESTES; JAMES W. ERICKSON

2001-01-01

21

atonal and achaete-scute-related genes in the annelid Platynereis dumerilii: insights into the evolution of neural basic-Helix-Loop-Helix genes  

Microsoft Academic Search

BACKGROUND: Functional studies in model organisms, such as vertebrates and Drosophila, have shown that basic Helix-loop-Helix (bHLH) proteins have important roles in different steps of neurogenesis, from the acquisition of neural fate to the differentiation into specific neural cell types. However, these studies highlighted many differences in the expression and function of orthologous bHLH proteins during neural development between vertebrates

Elena Simionato; Pierre Kerner; Nicolas Dray; Martine Le Gouar; Valérie Ledent; Detlev Arendt; Michel Vervoort

2008-01-01

22

INTRODUCTION Basic helix-loop-helix (bHLH) proteins constitute a large  

E-print Network

regulators that are characterized by a basic DNA-binding domain contiguous with a dimerization domain factors, thus setting off a cascade of gene regulation that implements the particular developmental-protein Daughterless (Da) are responsible for specifying most CNS and external sensory neural precursors (Campuzano

Delidakis, Christos

23

The basic helix-loop-helix differentiation factor Nex1/MATH-2 functions as a key activator of the GAP-43 gene  

PubMed Central

Nex1/MATH-2 is a neurogenic basic Helix-Loop-Helix (bHLH) transcription factor that belongs to the NeuroD subfamily. Its expression parallels that of the GAP-43 gene and peaks during brain development, when neurite outgrowth and synaptogenesis are highly active. We previously observed a direct correlation between the levels of expression of Nex1 and GAP-43 proteins, which resulted in extensive neurite outgrowth and neuronal differentiation of PC12 cells in the absence of nerve growth factor. Since the GAP-43 gene is a target for bHLH regulation, we investigated whether Nex1 could regulate the activity of the GAP-43 promoter. We found that among the members of the NeuroD subfamily, Nex1 promoted maximal activity of the GAP-43 promoter. The Nex1-mediated activity is restricted to the conserved E1–E2 cluster located near the major transcription start sites. By electrophoretic mobility shift assay and site-directed mutagenesis, we showed that Nex1 binds as homodimers and that the E1 E-box is a high affinity binding site. We further found that Nex1 released the ME1 E-protein-mediated repression in a concentration dependent manner. Thus, the E1–E2 cluster has a dual function: it can mediate activation or repression depending on the interacting bHLH proteins. Finally, a series of N-terminal and C-terminal deletions revealed that Nex1 transcriptional activity is linked to two distinct transactivation domains, TAD1 and TAD2, with TAD1 being unique to Nex1. Together, our results suggest that Nex1 may engage in selective interactions with components of the core transcriptional machinery whose assembly is dictated by the architecture of the GAP-43 promoter and cellular environment. PMID:12562512

Uittenbogaard, Martine; Martinka, Debra L.; Chiaramello, Anne

2006-01-01

24

Classification and evolutionary analysis of the basic helix-loop-helix gene family in the green anole lizard, Anolis carolinensis.  

PubMed

Helix-loop-helix (bHLH) proteins play essential regulatory roles in a variety of biological processes. These highly conserved proteins form a large transcription factor superfamily, and are commonly identified in large numbers within animal, plant, and fungal genomes. The bHLH domain has been well studied in many animal species, but has not yet been characterized in non-avian reptiles. In this study, we identified 102 putative bHLH genes in the genome of the green anole lizard, Anolis carolinensis. Based on phylogenetic analysis, these genes were classified into 43 families, with 43, 24, 16, 3, 10, and 3 members assigned into groups A, B, C, D, E, and F, respectively, and 3 members categorized as "orphans". Within-group evolutionary relationships inferred from the phylogenetic analysis were consistent with highly conserved patterns observed for introns and additional domains. Results from phylogenetic analysis of the H/E(spl) family suggest that genome and tandem gene duplications have contributed to this family's expansion. Our classification and evolutionary analysis has provided insights into the evolutionary diversification of animal bHLH genes, and should aid future studies on bHLH protein regulation of key growth and developmental processes. PMID:23756994

Liu, Ake; Wang, Yong; Zhang, Debao; Wang, Xuhua; Song, Huifang; Dang, Chunwang; Yao, Qin; Chen, Keping

2013-08-01

25

The SUMO Pathway Promotes Basic Helix-Loop-Helix Proneural Factor Activity via a Direct Effect on the Zn Finger Protein Senseless  

PubMed Central

During development, proneural transcription factors of the basic helix-loop-helix (bHLH) family are required to commit cells to a neural fate. In Drosophila neurogenesis, a key mechanism promoting sense organ precursor (SOP) fate is the synergy between proneural factors and their coactivator Senseless in transcriptional activation of target genes. Here we present evidence that posttranslational modification by SUMO enhances this synergy via an effect on Senseless protein. We show that Senseless is a direct target for SUMO modification and that mutagenesis of a predicted SUMOylation motif in Senseless reduces Senseless/proneural synergy both in vivo and in cell culture. We propose that SUMOylation of Senseless via lysine 509 promotes its synergy with proneural proteins during transcriptional activation and hence regulates an important step in neurogenesis leading to the formation and maturation of the SOPs. PMID:22586269

Chen, Angela; Huang, Yan Chang; Wang, Pin Yao; Kemp, Sadie E.

2012-01-01

26

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

PubMed Central

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

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

1997-01-01

27

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

PubMed

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

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

2013-11-01

28

Arabidopsis Basic Helix-Loop-Helix Transcription Factors MYC2, MYC3, and MYC4 Regulate Glucosinolate Biosynthesis, Insect Performance, and Feeding Behavior[W][OPEN  

PubMed Central

Arabidopsis thaliana plants fend off insect attack by constitutive and inducible production of toxic metabolites, such as glucosinolates (GSs). A triple mutant lacking MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that are known to additively control jasmonate-related defense responses, was shown to have a highly reduced expression of GS biosynthesis genes. The myc2 myc3 myc4 (myc234) triple mutant was almost completely devoid of GS and was extremely susceptible to the generalist herbivore Spodoptera littoralis. On the contrary, the specialist Pieris brassicae was unaffected by the presence of GS and preferred to feed on wild-type plants. In addition, lack of GS in myc234 drastically modified S. littoralis feeding behavior. Surprisingly, the expression of MYB factors known to regulate GS biosynthesis genes was not altered in myc234, suggesting that MYC2/MYC3/MYC4 are necessary for direct transcriptional activation of GS biosynthesis genes. To support this, chromatin immunoprecipitation analysis showed that MYC2 binds directly to the promoter of several GS biosynthesis genes in vivo. Furthermore, yeast two-hybrid and pull-down experiments indicated that MYC2/MYC3/MYC4 interact directly with GS-related MYBs. This specific MYC–MYB interaction plays a crucial role in the regulation of defense secondary metabolite production and underlines the importance of GS in shaping plant interactions with adapted and nonadapted herbivores. PMID:23943862

Schweizer, Fabian; Fernandez-Calvo, Patricia; Zander, Mark; Diez-Diaz, Monica; Fonseca, Sandra; Glauser, Gaetan; Lewsey, Mathew G.; Ecker, Joseph R.; Solano, Roberto; Reymond, Philippe

2013-01-01

29

epicardin: A novel basic helix-loop-helix transcription factor gene expressed in epicardium, branchial arch myoblasts, and mesenchyme of developing lung, gut, kidney, and gonads.  

PubMed

We report the cloning, chromosomal localization, and analysis of the expression pattern of epicardin, a member of the basic helix-loop-helix (bHLH) family of transcription factors. Within its bHLH domain, the human and murine epicardin genes were most similar to paraxis, a bHLH gene important for segmentation of embryonic paraxial mesoderm. In situ hybridization studies revealed strong epicardin expression in murine embryos at 9.5 days postcoitum (dpc) in a region of the septum transversum at the base of the heart known as the proepicardial organ. This mesenchymal structure extends villous projections from which epicardial precursor cells emerge and migrate out over the surface of the myocardium. Strong expression was seen in individual migratory cells and clusters at 9.5 dpc and in a continuous epicardial cell layer in more mature hearts. Also from 9.5 dpc, epicardin transcripts were seen in endocardial cushions of the atrioventricular canal and outflow tract, in skeletal myoblasts within branchial arches and in condensing mesenchyme of gut, kidney, urinary tract, gonads, spleen, and lung. Northern analysis showed that expression persisted in mature visceral organs and heart, but was transient in skeletal muscle. The central role played by bHLH factors in pathways for tissue determination in the embryo suggests a function for epicardin in specification of select mesodermal cell populations associated with heart, cranial skeletal muscle, gut, and urogenital system. PMID:9733105

Robb, L; Mifsud, L; Hartley, L; Biben, C; Copeland, N G; Gilbert, D J; Jenkins, N A; Harvey, R P

1998-09-01

30

Genome-wide binding of the basic helix-loop-helix myogenic inhibitor musculin has substantial overlap with MyoD: implications for buffering activity  

PubMed Central

Background Musculin (MSC) is a basic helix-loop-helix transcription factor that inhibits myogenesis during normal development and contributes to the differentiation defect in rhabdomyosarcoma. As one of many transcription factors that impede myogenesis, its binding on a genome-wide scale relative to the widespread binding of the myogenic factor MyoD is unknown. Methods Chromatin immunoprecipitation coupled to high-throughput sequencing was performed for endogenous MSC in rhabdomyosarcoma cells and its binding was compared to that of MyoD in the same type of cells. Results MSC binds throughout the genome, in a pattern very similar to MyoD. Its binding overlaps strongly with regions enriched for acetylated histone H4, as well as regions that score high for DNase hypersensitivity in human myoblasts. In contrast to MyoD, MSC has a more relaxed binding sequence preference in the nucleotides that flank the core E-box motif. Conclusions The myogenic inhibitor MSC binds throughout the genome of rhabdomyosarcoma cells, in a pattern highly similar to that of MyoD, suggesting a broad role in buffering the activity of MyoD in development and rhabdomyosarcomas. PMID:24175993

2013-01-01

31

Abnormal Heart Development and Lung Remodeling in Mice Lacking the Hypoxia-Inducible Factor-Related Basic Helix-Loop-Helix PAS Protein NEPAS?  

PubMed Central

Hypoxia-inducible factors (HIFs) are crucial for oxygen homeostasis during both embryonic development and postnatal life. Here we show that a novel HIF family basic helix-loop-helix (bHLH) PAS (Per-Arnt-Sim) protein, which is expressed predominantly during embryonic and neonatal stages and thereby designated NEPAS (neonatal and embryonic PAS), acts as a negative regulator of HIF-mediated gene expression. NEPAS mRNA is derived from the HIF-3? gene by alternative splicing, replacing the first exon of HIF-3? with that of inhibitory PAS. NEPAS can dimerize with Arnt and exhibits only low levels of transcriptional activity, similar to that of HIF-3?. NEPAS suppressed reporter gene expression driven by HIF-1? and HIF-2?. By generating mice with a targeted disruption of the NEPAS/HIF-3? locus, we found that homozygous mutant mice (NEPAS/HIF-3??/?) were viable but displayed enlargement of the right ventricle and impaired lung remodeling. The expression of endothelin 1 and platelet-derived growth factor ? was increased in the lung endothelial cells of NEPAS/HIF-3?-null mice. These results demonstrate a novel regulatory mechanism in which the activities of HIF-1? and HIF-2? are negatively regulated by NEPAS in endothelial cells, which is pertinent to lung and heart development during the embryonic and neonatal stages. PMID:18070924

Yamashita, Toshiharu; Ohneda, Osamu; Nagano, Masumi; Iemitsu, Motoyuki; Makino, Yuichi; Tanaka, Hirotoshi; Miyauchi, Takashi; Goto, Katsutoshi; Ohneda, Kinuko; Fujii-Kuriyama, Yoshiaki; Poellinger, Lorenz; Yamamoto, Masayuki

2008-01-01

32

Dual DNA binding specificity of ADD1/SREBP1 controlled by a single amino acid in the basic helix-loop-helix domain.  

PubMed Central

Adipocyte determination- and differentiation-dependent factor 1 (ADD1), a member of the basic helix-loop-helix (bHLH) family of transcription factors, has been associated with both adipocyte differentiation and cholesterol homeostasis (in which case it has been termed SREBP1). Using PCR-amplified binding analysis, we demonstrate that ADD1/SREBP1 has dual DNA sequence specificity, binding to both an E-box motif (ATCACGTGA) and a non-E-box sequence previously shown to be important in cholesterol metabolism, sterol regulatory element 1 (SRE-1; ATCACCCCAC). The ADD1/SREBP1 consensus E-box site is similar to a regulatory sequence designated the carbohydrate response element, defined by its ability to regulate transcription in response to carbohydrate in genes involved in fatty acid and triglyceride metabolism in liver and fat. When expressed in fibroblasts, ADD1/SREBP1 activates transcription through both the carbohydrate response E-box element and SRE-1. Substitution of an atypical tyrosine in the basic region of ADD1/SREBP1 to an arginine found in most bHLH protein causes a restriction to only E-box binding. Conversely, substitution of a tyrosine for the equivalent arginine in another bHLH protein, upstream stimulatory factor, allows this factor to acquire a dual binding specificity similar to that of ADD1/SREBP1. Promoter activation by ADD1/SREBP1 through the carbohydrate response element E box is not sensitive to the tyrosine-to-arginine mutation, while activation through SRE-1 is completely suppressed. These data illustrate that ADD1/SREBP1 has dual DNA sequence specificity controlled by a single amino acid residue; this dual specificity may provide a novel mechanism to coordinate different pathways of lipid metabolism. PMID:7739539

Kim, J B; Spotts, G D; Halvorsen, Y D; Shih, H M; Ellenberger, T; Towle, H C; Spiegelman, B M

1995-01-01

33

Targeting the Microphthalmia Basic Helix-Loop-Helix-Leucine Zipper Transcription Factor to a Subset of E-Box Elements In Vitro and In Vivo  

PubMed Central

The development of melanocytes, which are pigment-producing cells responsible for skin, hair, and eye color, is absolutely dependent on the action of the microphthalmia basic helix-loop-helix–leucine zipper (bHLH-LZ) transcription factor (Mi); mice lacking a functional Mi protein are entirely devoid of pigment cells. Mi has been shown to activate transcription of the tyrosinase, TRP-1, TRP-2, and QNR-71 genes through specific E-box elements, most notably the highly conserved M box. We investigated the mechanism which enables Mi to be recruited specifically to a restricted subset of E boxes in target promoters while being prevented from binding E-box elements in other promoters. We show both in vitro and in vivo that the presence of a T residue flanking a CATGTG E box is an essential determinant of the ability of Mi to bind DNA, and we successfully predict that the CATGTG E box from the P gene would not bind Mi. In contrast, no specific requirement for the sequences flanking a CACGTG E box was observed, and no binding to an atypical E box in the c-Kit promoter was detected. The relevance of these observations to the control of melanocyte-specific gene expression was highlighted by the fact that the E-box elements located in the tyrosinase, TRP-1, TRP-2, and QNR-71 promoters without exception possess a 5? flanking T residue which is entirely conserved between species as diverse as man and turtle. The ability of Mi to discriminate between different E-box motifs provides a mechanism to restrict the repertoire of genes which are likely to be regulated by Mi and provides insight into the ability of bHLH-LZ transcription factors to achieve the specificity required for the precise coordination of transcription during development. PMID:9819381

Aksan, I.; Goding, C. R.

1998-01-01

34

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

PubMed Central

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

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

2005-01-01

35

PIAS1 Activates the Expression of Smooth Muscle Cell Differentiation Marker Genes by Interacting with Serum Response Factor and Class I Basic Helix-Loop-Helix Proteins  

PubMed Central

Although a critical component of vascular disease is modulation of the differentiated state of vascular smooth muscle cells (SMC), the mechanisms governing SMC differentiation are relatively poorly understood. We have previously shown that E-boxes and the ubiquitously expressed class I basic helix-loop-helix (bHLH) proteins, including E2-2 and E12, are important in regulation of the SMC differentiation marker gene, the SM ?-actin gene. The aim of the present study was to identify proteins that bind to class I bHLH proteins in SMC and modulate transcriptional regulation of SMC differentiation marker genes. Herein we report that members of the protein inhibitor of activated STAT (PIAS) family interact with class I bHLH factors as well as serum response factor (SRF). PIAS1 interacted with E2-2 and E12 based on yeast two-hybrid screens, mammalian two-hybrid assays, and/or coimmunoprecipitation assays. Overexpression of PIAS1 significantly activated the SM ?-actin promoter and mRNA expression, as well as SM myosin heavy chain and SM22?, whereas a small interfering RNA for PIAS1 decreased activity of these promoters, as well as endogenous mRNA expression, and SRF binding to SM ?-actin promoter within intact chromatin in cultured SMC. Of significance, PIAS1 bound to SRF and activated SM ?-actin promoter expression in wild-type but not SRF?/? embryonic stem cells. These results provide novel evidence that PIAS1 modulates transcriptional activation of SMC marker genes through cooperative interactions with both SRF and class I bHLH proteins. PMID:16135793

Kawai-Kowase, Keiko; Kumar, Meena S.; Hoofnagle, Mark H.; Yoshida, Tadashi; Owens, Gary K.

2005-01-01

36

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

PubMed

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

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

2014-12-01

37

Expression of the gene for Dec2, a basic helix-loop-helix transcription factor, is regulated by a molecular clock system.  

PubMed

Dec2, a member of the basic helix-loop-helix superfamily, is a recently confirmed regulatory protein for the clockwork system. Transcripts of Dec2, as well as those of its related gene Dec1, exhibit a striking circadian oscillation in the suprachiasmatic nucleus, and Dec2 inhibits transcription from the Per1 promoter induced by Clock/Bmal1 [Honma, Kawamoto, Takagi, Fujimoto, Sato, Noshiro, Kato and Honma (2002) Nature (London) 419, 841-844]. It is known that mammalian circadian rhythms are controlled by molecular clockwork systems based on negative-feedback loop(s), but the molecular mechanisms for the circadian regulation of Dec2 gene expression have not been clarified. We show here that transcription of the Dec2 gene is regulated by several clock molecules and a negative-feedback loop. Luciferase and gel retardation assays showed that expression of Dec2 was negatively regulated by binding of Dec2 or Dec1 to two CACGTG E-boxes in the Dec2 promoter. Forced expression of Clock/Bmal1 and Clock/Bmal2 markedly increased Dec2 mRNA levels, and up-regulated the transcription of the Dec2 gene through the CACGTG E-boxes. Like Dec, Cry and Per also suppressed Clock/Bmal-induced transcription from the Dec2 promoter. Moreover, the circadian expression of Dec2 transcripts was abolished in the kidney of Clock/Clock mutant mice. These findings suggest that the Clock/Bmal heterodimer enhances Dec2 transcription via the CACGTG E-boxes, whereas the induced transcription is suppressed by Dec2, which therefore must contribute to its own rhythmic expression. In addition, Cry and Per may also modulate Dec2 transcription. PMID:15147242

Hamaguchi, Hidenori; Fujimoto, Katsumi; Kawamoto, Takeshi; Noshiro, Mitsuhide; Maemura, Koji; Takeda, Norihiko; Nagai, Ryozo; Furukawa, Masae; Honma, Sato; Honma, Ken-ichi; Kurihara, Hidemi; Kato, Yukio

2004-08-15

38

MicroRNA-212 Post-Transcriptionally Regulates Oocyte-Specific Basic-Helix-Loop-Helix Transcription Factor, Factor in the Germline Alpha (FIGLA), during Bovine Early Embryogenesis  

PubMed Central

Factor in the germline alpha (FIGLA) is an oocyte-specific basic helix-loop-helix transcription factor essential for primordial follicle formation and expression of many genes required for folliculogenesis, fertilization and early embryonic survival. Here we report the characterization of bovine FIGLA gene and its regulation during early embryogenesis. Bovine FIGLA mRNA expression is restricted to gonads and is detected in fetal ovaries harvested as early as 90 days of gestation. FIGLA mRNA and protein are abundant in germinal vesicle and metaphase II stage oocytes, as well as in embryos from pronuclear to eight-cell stage but barely detectable at morula and blastocyst stages, suggesting that FIGLA might be a maternal effect gene. Recent studies in zebrafish and mice have highlighted the importance of non-coding small RNAs (microRNAs) as key regulatory molecules targeting maternal mRNAs for degradation during embryonic development. We hypothesized that FIGLA, as a maternal transcript, is regulated by microRNAs during early embryogenesis. Computational predictions identified a potential microRNA recognition element (MRE) for miR-212 in the 3’ UTR of the bovine FIGLA mRNA. Bovine miR-212 is expressed in oocytes and tends to increase in four-cell and eight-cell stage embryos followed by a decline at morula and blastocyst stages. Transient transfection and reporter assays revealed that miR-212 represses the expression of FIGLA in a MRE dependent manner. In addition, ectopic expression of miR-212 mimic in bovine early embryos dramatically reduced the expression of FIGLA protein. Collectively, our results demonstrate that FIGLA is temporally regulated during bovine early embryogenesis and miR-212 is an important negative regulator of FIGLA during the maternal to zygotic transition in bovine embryos. PMID:24086699

Tripurani, Swamy K.; Wee, Gabbine; Lee, Kyung-Bon; Smith, George W.; Wang, Lei; JianboYao

2013-01-01

39

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

PubMed

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

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

2001-12-15

40

Molecular Characterization of Helix-Loop-Helix Peptides  

Microsoft Academic Search

A class of regulators of eokaryotic gene expression contains a conserved amino acid sequence responsible for protein oligomerization and binding to DNA. This structure consists of an arginine- and lysine-rich basic region followed by a helix-loop-helix motif, which together mediate specific binding to DNA. Peptides were prepared that span this motif in the MyoD protein; in solution, they formed alpha-helical

Spencer J. Anthony-Cahill; Pamela A. Benfield; Robert Fairman; Zelda R. Wasserman; Stephen L. Brenner; Walter F. Stafford III; Christian Altenbach; Wayne L. Hubbell; William F. Degrado

1992-01-01

41

A novel type of PTD, common helix–loop–helix motif, could efficiently mediate protein transduction into mammalian cells  

Microsoft Academic Search

Protein transduction domains (PTDs), such as HIV TAT PTD, have been widely used as delivery tools into living cells. Here we reported for the first time that the helix–loop–helix (HLH) domain of basic helix–loop–helix (bHLH) family was a novel type of PTD. Efficient internalization has been obtained with HLH domains derived from bHLH proteins, NeuroD\\/BETA2, Neurogenin3, and Mitf, in various

Jing Chen; Ge Li; Jun Lu; Lei Chen; Yin Huang; Huiling Wu; Jiaxin Zhang; Daru Lu

2006-01-01

42

Overexpression of Stra13, a novel retinoic acid-inducible gene of the basic helix-loop-helix family, inhibits mesodermal and promotes neuronal differentiation of P19 cells  

PubMed Central

We report the cDNA cloning of Stra13, a novel retinoic acid (RA)-inducible gene from P19 embryonal carcinoma cells that encodes a basic helix–loop–helix (bHLH) protein that shows the highest sequence similarities to the Drosophila Hairy and Enhancer of split and mouse Hes proteins. Stra13 does not bind to the known consensus motifs (E-box and N-box) for bHLH proteins, but can repress activated transcription (through an ?-helix rich domain) in part by interaction with general factors of the basal transcription machinery. During mouse embryogenesis, Stra13 RNA is expressed in the neuroectoderm, and also in a number of mesodermal and endodermal derivatives. Remarkably, overexpression of Stra13 in P19 cells results in neuronal differentiation in monolayer culture, under conditions where wild-type P19 cells only undergo mesodermal/endodermal differentiation. This neuronal differentiation is accompanied by an altered expression of mesodermal and neuronal markers, indicating that Stra13 could be one of the earliest RA target genes whose expression is required for repression of mesodermal/endodermal differentiation and/or induction of neuronal differentiation when P19 cell aggregates are exposed to RA. Our results raise the possibility that Stra13 could be involved as a repressor in a number of decision events occurring during differentiation of various cell lineages. PMID:9284045

Boudjelal, Mohamed; Taneja, Reshma; Matsubara, Shyuichiro; Bouillet, Philippe; Dolle, Pascal; Chambon, Pierre

1997-01-01

43

Low Resolution Structural Models of the Basic Helix-Loop-Helix Leucine Zipper Domain of Upstream Stimulatory Factor 1 and Its Complexes with DNA from Small Angle X-Ray Scattering Data  

PubMed Central

The upstream stimulatory factor 1 (USF1) belongs to the basic helix-loop-helix leucine zipper (b/HLH/Z) transcription factor family, recognizing the CACGTG DNA motive as a dimer and playing an important role in the regulation of transcription in a variety of cellular and viral promoters. In this study we investigate the USF1 b/HLH/Z domain and its complexes with DNA by small angle x-ray scattering. We present low resolution structural models of monomeric b/HLH/Z USF1 in the absence of DNA and USF1 dimeric (b/HLH/Z)2-DNA and tetrameric (b/HLH/Z)4-DNA2 complexes. The data reveal a concentration-dependent USF1 dimer (b/HLH/Z)2-DNA-tetramer (b/HLH/Z)4-DNA2 equilibrium. The ability of b/HLH/Z USF1 to form a tetrameric assembly on two distant DNA binding sites as a consequence of increased protein concentration suggest a USF1 concentration-dependant mechanism of transcription activation involving DNA loop formation. PMID:17827227

Lamber, Ekaterina P.; Wilmanns, Matthias; Svergun, Dmitri I.

2008-01-01

44

Low resolution structural models of the basic helix-loop-helix leucine zipper domain of upstream stimulatory factor 1 and its complexes with DNA from small angle X-ray scattering data.  

PubMed

The upstream stimulatory factor 1 (USF1) belongs to the basic helix-loop-helix leucine zipper (b/HLH/Z) transcription factor family, recognizing the CACGTG DNA motive as a dimer and playing an important role in the regulation of transcription in a variety of cellular and viral promoters. In this study we investigate the USF1 b/HLH/Z domain and its complexes with DNA by small angle x-ray scattering. We present low resolution structural models of monomeric b/HLH/Z USF1 in the absence of DNA and USF1 dimeric (b/HLH/Z)(2)-DNA and tetrameric (b/HLH/Z)(4)-DNA(2) complexes. The data reveal a concentration-dependent USF1 dimer (b/HLH/Z)(2)-DNA-tetramer (b/HLH/Z)(4)-DNA(2) equilibrium. The ability of b/HLH/Z USF1 to form a tetrameric assembly on two distant DNA binding sites as a consequence of increased protein concentration suggest a USF1 concentration-dependant mechanism of transcription activation involving DNA loop formation. PMID:17827227

Lamber, Ekaterina P; Wilmanns, Matthias; Svergun, Dmitri I

2008-01-01

45

Ectopic expression of a basic helix-loop-helix gene transactivates parallel pathways of proanthocyanidin biosynthesis. structure, expression analysis, and genetic control of leucoanthocyanidin 4-reductase and anthocyanidin reductase genes in Lotus corniculatus.  

PubMed

Proanthocyanidins (PAs) are plant secondary metabolites and are composed primarily of catechin and epicatechin units in higher plant species. Due to the ability of PAs to bind reversibly with plant proteins to improve digestion and reduce bloat, engineering this pathway in leaves is a major goal for forage breeders. Here, we report the cloning and expression analysis of anthocyanidin reductase (ANR) and leucoanthocyanidin 4-reductase (LAR), two genes encoding enzymes committed to epicatechin and catechin biosynthesis, respectively, in Lotus corniculatus. We show the presence of two LAR gene families (LAR1 and LAR2) and that the steady-state levels of ANR and LAR1 genes correlate with the levels of PAs in leaves of wild-type and transgenic plants. Interestingly, ANR and LAR1, but not LAR2, genes produced active proteins following heterologous expression in Escherichia coli and are affected by the same basic helix-loop-helix transcription factor that promotes PA accumulation in cells of palisade and spongy mesophyll. This study provides direct evidence that the same subclass of transcription factors can mediate the expression of the structural genes of both branches of PA biosynthesis. PMID:17098849

Paolocci, Francesco; Robbins, Mark P; Madeo, Laura; Arcioni, Sergio; Martens, Stefan; Damiani, Francesco

2007-01-01

46

The Basic Helix-Loop-Helix Transcription Factor MYC2 Directly Represses PLETHORA Expression during Jasmonate-Mediated Modulation of the Root Stem Cell Niche in Arabidopsis[W][OA  

PubMed Central

The root stem cell niche, which in the Arabidopsis thaliana root meristem is an area of four mitotically inactive quiescent cells (QCs) and the surrounding mitotically active stem cells, is critical for root development and growth. We report here that during jasmonate-induced inhibition of primary root growth, jasmonate reduces root meristem activity and leads to irregular QC division and columella stem cell differentiation. Consistently, jasmonate reduces the expression levels of the AP2-domain transcription factors PLETHORA1 (PLT1) and PLT2, which form a developmentally instructive protein gradient and mediate auxin-induced regulation of stem cell niche maintenance. Not surprisingly, the effects of jasmonate on root stem cell niche maintenance and PLT expression require the functioning of MYC2/JASMONATE INSENSITIVE1, a basic helix-loop-helix transcription factor that involves versatile aspects of jasmonate-regulated gene expression. Gel shift and chromatin immunoprecipitation experiments reveal that MYC2 directly binds the promoters of PLT1 and PLT2 and represses their expression. We propose that MYC2-mediated repression of PLT expression integrates jasmonate action into the auxin pathway in regulating root meristem activity and stem cell niche maintenance. This study illustrates a molecular framework for jasmonate-induced inhibition of root growth through interaction with the growth regulator auxin. PMID:21954460

Chen, Qian; Sun, Jiaqiang; Zhai, Qingzhe; Zhou, Wenkun; Qi, Linlin; Xu, Li; Wang, Bao; Chen, Rong; Jiang, Hongling; Qi, Jing; Li, Xugang; Palme, Klaus; Li, Chuanyou

2011-01-01

47

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

SciTech Connect

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

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

2012-10-15

48

Myocardial activation of the human cardiac alpha-actin promoter by helix-loop-helix proteins.  

PubMed Central

The cardiac alpha-actin gene is expressed in both heart and skeletal muscle. In skeletal myogenic cells, the 177-base-pair promoter of the human cardiac alpha-actin (HCA) gene requires three transcription factors for activation: Sp1, serum response factor (SRF), and MyoD. However, MyoD is undetectable in heart. To search for a functional equivalent of MyoD, we analyzed the transcriptional regulation of the HCA promoter in primary cultures of rat cardiac myocytes. The same DNA sequence elements recognized by SRF, Sp1, and MyoD and required for HCA transcription in skeletal muscle cells were also found to be necessary for expression in cardiomyocytes. Overexpression of Id, a negative regulator of basic helix-loop-helix proteins, selectively attenuated expression of the HCA promoter. Cardiomyocyte nuclei contain a protein complex that specifically interacts with the same required sequence (E box) in the HCA promoter that is bound by MyoD in skeletal myogenic cells. Furthermore, these complexes contain a peptide that is a member of the E2A family of basic helix-loop-helix proteins. Cardiomyocyte nuclei appear to be enriched for a protein that can bind to the E-box site as dimers with the E12 protein. These results suggest that a member of the basic helix-loop-helix family, together with SRF and Sp1, activates the HCA promoter in heart. Alternative strategies for myocardial transcription of HCA are discussed. Images PMID:1570331

Sartorelli, V; Hong, N A; Bishopric, N H; Kedes, L

1992-01-01

49

The Helix-Loop-Helix Factors Id3 and E47 Are Novel Regulators of Adiponectin  

Microsoft Academic Search

Adiponectin is an adipocyte-derived cytokine with beneficial effects on insulin sensitivity and the development of atherosclerosis. Id3 is a helix-loop-helix factor that binds to E-proteins such as E47 and inhibits their binding to DNA. Although the helix-loop-helix factor sterol regulatory element binding protein (SREBP)-1c is a known activator of adiponectin transcription, this study provides the first evidence of a role

Amanda C. Doran; Nahum Meller; Alexis Cutchins; Hamid Deliri; R. Parker Slayton; Stephanie N. Oldham; Jae B. Kim; Susanna R. Keller; Coleen A. McNamara

2010-01-01

50

ADD1: a novel helix-loop-helix transcription factor associated with adipocyte determination and differentiation.  

PubMed Central

DNA-binding proteins containing the basic helix-loop-helix (bHLH) domain have been implicated in lineage determination and the regulation of specific gene expression in a number of cell types. By oligonucleotide screening of an adipocyte cDNA expression library, we have identified a novel member of the bHLH-leucine zipper transcription factor family designated ADD1. ADD1 mRNA is expressed predominantly in brown adipose tissue in vivo and is regulated during both determination and differentiation of cultured adipocyte cell lines. ADD1 can function as a sequence-specific transcriptional activator in that it stimulates expression of a chloramphenicol acetyltransferase vector containing multiple ADD1 binding sequences but is unable to activate the myosin light-chain enhancer, which contains multiple binding sites for another bHLH factor, MyoD. ADD1 can also activate transcription through a binding site present in the 5'-flanking region of the fatty acid synthetase gene which is expressed in a differentiation-dependent manner in adipose cells. These data suggest that ADD1 plays a role in the regulation of determination- and differentiation-specific gene expression in adipocytes. Images PMID:8336713

Tontonoz, P; Kim, J B; Graves, R A; Spiegelman, B M

1993-01-01

51

A helix-loop-helix protein related to the immunoglobulin E box-binding proteins.  

PubMed Central

A human cDNA encoding a novel protein in the helix-loop-helix family has been isolated by screening a bacteriophage expression library with a probe containing the binding site for major late transcription factor. The protein encoded by this cDNA, TFEB, probably recognizes E-box sequences in the heavy-chain immunoglobulin enhancer. Images PMID:2115126

Carr, C S; Sharp, P A

1990-01-01

52

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

PubMed

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

Beisswenger, Michael; Cabrele, Chiara

2014-09-01

53

Preferred sequences for DNA recognition by the TAL1 helix-loop-helix proteins  

SciTech Connect

Tumor-specific activation of the TAL1 gene is the most common genetic alteration seen in patients with T-cell acute lymphoblastic leukemia. The TAL1 gene products contain the basic helix-loop-helix (bHLH) domain, a protein dimerization and DNA-binding motif common to several known transcription factors. A binding-site selection procedure has now been used to evaluate the DNA recognition properties of TAL1. These studies demonstrate that TAL1 polypeptides do not have intrinsic DNA-binding activity, presumably because of their inability to form bHLH homodimers. However, TAL1 readily interacts with any of the known class A bHLH proteins (E12, E47, E2-2, and HEB) to form heterodimers that bind DNA in a sequence-specific manner. The TAL1 heterodimers preferentially recognize a subset of E-box elements (CANNTG) that can be represented by the consensus sequence AACAGATGGT. This consensus is composed of half-sites for recognition by the participating class A bHLH polypeptide (AACAG) and the TAL1 polypeptide (ATGGT). TAL1 heterodimers with DNA-binding activity are readily detected in nuclear extracts of Jurkat, a leukemic cell line derived from a patient with T-cell acute lymphoblastic leukemia. Hence, TAL1 is likely to bind and regulate the transcription of a unique subset of subordinate target genes, some of which may mediate the malignant function of TAL1 during T-cell leukemogenesis. 48 refs., 10 figs.

Hai-Ling Hsu; Lan Huang; Julia Tsou Tsan [Univ. of Texas Southwestern Medical Center, Dallas, TX (United States)] [and others

1994-02-01

54

Common Regulation of Growth Arrest and Differentiation of Osteoblasts by Helix-Loop-Helix Factors  

PubMed Central

Cellular differentiation entails the coordination of cell cycle arrest and tissue-specific gene expression. We investigated the involvement of basic helix-loop-helix (bHLH) factors in differentiation of osteoblasts using the human osteoblastic cell line MG63. Serum starvation induced growth arrest at G1 phase, accompanied by expression of cyclin-dependent kinase inhibitor p21WAF1/Cip1. Reporter assays with the p21 gene promoter demonstrated that the combination of E2A (E12 or E47) and coactivator CBP was responsible for p21 induction independent of p53. Twist inhibited E2A-CBP-dependent activation of the exogenous and endogenous p21 promoters. Ids similarly inhibited the exogenously transfected p21 promoter; however less antagonistic effect on the endogenous p21 promoter was observed. Twist was predominantly present in nuclei in MG63 cells growing in complete medium, while it localized mainly in the cytoplasm after serum starvation. The fibroblast growth factor receptor 3 gene (FGFR3), which generates signals leading to differentiation of osteoblasts, was found to be controlled by the same transcriptional regulation as the p21 gene. E2A and Twist influenced alkaline phosphatase expression, a consensus marker of osteoblast differentiation. Expression of E2A and FGFR3 was seen at the location of osteoblast differentiation in the calvaria of mouse embryos, implicating bHLH molecules in physiological osteoblast differentiation. These results demonstrate that a common regulatory system is involved in at least two distinct steps in osteoblastic differentiation. Our results also provide the molecular basis of Saethre-Chotzen syndrome, caused by mutations of the TWIST and FGFR3 genes. PMID:11585922

Funato, Noriko; Ohtani, Kiyoshi; Ohyama, Kimie; Kuroda, Takayuki; Nakamura, Masataka

2001-01-01

55

Regulation of TCF ETS-domain transcription factors by helix-loop-helix motifs  

Microsoft Academic Search

DNA binding by the ternary complex factor (TCF) subfamily of ETS-domain transcription factors is tightly regulated by intramolecular and intermolecu- lar interactions. The helix-loop-helix (HLH)-contain- ing Id proteins are trans-acting negative regulators of DNA binding by the TCFs. In the TCF, SAP-2\\/Net\\/ ERP, intramolecular inhibition of DNA binding is promoted by the cis-acting NID region that also con- tains an

Julie Stinson; Toshiaki Inoue; Paula Yates; Anne Clancy; John D. Norton; Andrew D. Sharrocks

2003-01-01

56

Transcription of the dominant-negative helix-loop-helix protein Id1 is regulated by a protein complex containing the immediate-early response gene Egr-1.  

PubMed Central

The expression of Id1, a helix-loop-helix protein which inhibits the activity of basic helix-loop-helix transcription factors, is down-regulated during cellular differentiation and cell cycle withdrawal both in tissue culture models and in mouse embryos. In order to study the mechanism of control of Idl expression, we have isolated a 210-bp enhancer element in the upstream region of the Id1 gene whose activity recapitulates Id1 expression in C2C12 muscle cells and C3H10T1/2 fibroblasts: i.e., this element is active in proliferating cells in the presence of serum and completely inactivated upon mitogen depletion, cell cycle withdrawal, and (in the case of C2C12) induced myoblast differentiation. Using linker-scanning mutations and site-directed mutagenesis in transient transfection experiments, we have identified two functional elements within the 210-bp enhancer which are required for proper serum responsiveness. One element (A) contains a consensus Egr-1 binding site and additional flanking sequences required for optimal activity, and the other element (B) fits no known consensus. Gel shift experiments demonstrate that the protein complex binding to the A site contains Egr-1 and other proteins. This complex as well as a protein complex that binds to the B site is lost within 24 h of serum depletion, correlating with the down-regulation of Id1 expression. On the basis of these findings, we propose that the regulation of the Id1 response to serum is mediated in part by the early response gene Egr-1 and as such provides a signaling link between the early-growth-response transcription factors and dominant-negative helix-loop-helix proteins. PMID:8628310

Tournay, O; Benezra, R

1996-01-01

57

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

PubMed Central

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 helix–loop–helix proteins. Students then used reverse transcription–polymerase chain reaction to determine which of the three genes is normally expressed in C. elegans. At the end of this laboratory activity, students were 1) to demonstrate a rudimentary knowledge of bioinformatics, including the ability to differentiate between “having” a gene and “expressing” a gene, and 2) to understand basic approaches to functional genomics, including one specific technique for assaying for gene expression. It was also anticipated that students would increase their skills at effectively communicating their research activities through written and/or oral presentation. This article describes the laboratory activity and the assessment of the effectiveness of the activity. PMID:12822036

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

2003-01-01

58

The helix-loop-helix protein Id-2 enhances cell proliferation and binds to the retinoblastoma protein.  

PubMed

Cell growth and differentiation are usually antagonistic. Proteins of the basic helix-loop-helix (bHLH) family bind DNA and play important roles in the differentiation of specific cell types. Id proteins heterodimerize with bHLH transcription factors, blocking their activation of lineage-specific gene expression and thereby inhibiting cellular differentiation. To examine the effect of Id-2 on cell proliferation, we overexpressed Id-2 in the human osteosarcoma cell line U2OS. Id-2 expression in U2OS reduced the serum requirement for growth and stimulated cellular proliferation by shortening the doubling time and increasing the percentage of cells in S phase. We demonstrated that Id-2 expression was able to reverse the inhibition of cellular proliferation and the block in cell cycle progression mediated by the product of the retinoblastoma tumor suppressor gene pRB. This effect was not associated with changes in the state of pRb phosphorylation in transfected cells. In vitro, unphosphorylated pRb from cell lysates specifically bound Id-2 but was not able to bind a mutated form of Id-2 lacking the HLH domain that also did not antagonize the growth arrest by pRb. In vitro-synthesized pRb containing mutations within the E1A/large T-binding pocket did not bind Id-2. However, wild-type pRb was able to bind to a region of Id-2 corresponding to only the HLH domain. In vivo, a physical association between Id-2 and pRb was seen in cross-linked extracts from SAOS-2 cells transfected with Id-2 and pRb. Our data identify a role for Id-2 in the regulation of cellular proliferation and suggest that the interaction between Id-2 and pRB is a molecular pathway over which synchronous changes in growth and differentiation are mediated in vivo. PMID:7926730

Iavarone, A; Garg, P; Lasorella, A; Hsu, J; Israel, M A

1994-06-01

59

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

PubMed Central

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

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

2014-01-01

60

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

PubMed

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

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

2014-07-01

61

Molecular cloning of ID4, a novel dominant negative helix-loop-helix human gene on chromosome 6p21.3-p22  

SciTech Connect

Transcription factors containing a basic helix-loop-helix (bHLH) motif regulate the expression of tissue-specific genes in a number of mammalian and insect systems. DNA-binding activity of the bHLH proteins is dependent upon formation of homo- and/or heterodimers. Dominant negative HLH proteins (Id-related genes) also contain the HLH-dimerization domain but lack the DNA-binding basic domain. Consequently, Id proteins inhibit binding to DNA and transcriptional transactivation by heterodimerization with bHLH proteins. The authors report here the cDNA sequence of a novel human HLH gene (HGMW-approved symbol ID4) that lacks the basic domain. ID4 is differentially expressed in adult organs in four mRNA molecules, which are presumably a result of differential splicing and/or alternative usage of the polyadenylation sites. Transfection experiments indicated that enforced expression of Id-4H protein inhibits the trans-activation of the muscle creatine kinase E-box enhancer by MyoD. Finally, the authors localized the ID4 gene to the chromosome 6p21-p22 region. 18 refs., 4 figs.

Pagliuca, A.; Bartoli, P.C.; Saccone, S. [Universita Federico II, Naples (Italy)] [and others] [Universita Federico II, Naples (Italy); and others

1995-05-01

62

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

SciTech Connect

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

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

1991-02-01

63

Functional Isoforms of IkB Kinase a (IKKa) Lacking Leucine Zipper and Helix-Loop-Helix Domains Reveal that IKKa and IKKb Have Different Activation Requirements  

Microsoft Academic Search

The activity of the NF-kB family of transcription factors is regulated principally by phosphorylation and subsequent degradation of their inhibitory IkB subunits. Site-specific serine phosphorylation of IkBs by two IkB kinases (IKKa (also known as CHUK) and IKKb) targets them for proteolysis. IKKa and -b have a unique structure, with an amino-terminal serine-threonine kinase catalytic domain and carboxy-proximal helix-loop-helix (HLH)

FERGUS R. MCKENZIE; MARGERY A. CONNELLY; DARLENE BALZARANO; JURGEN R. MULLER; ROMAS GELEZIUNAS; KENNETH B. MARCU

2000-01-01

64

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

Microsoft Academic Search

Regulatory genes are believed to play a large role in morphological diversification and are often characterized by elevated rates of evolution. Whether this rapid evolution is primarily due to adaptive differentiation or relaxed selective constraint remains an open question. We attempted to distinguish between these alternative outcomes in 2 transcription factors known to regulate the expression of anthocyanin pigmentation genes

Matthew A. Streisfeld; Mark D. Rausher

2007-01-01

65

Basic helix-loop-helix transcription factor Tcfl5 interacts with the Calmegin gene promoter in mouse spermatogenesis  

Microsoft Academic Search

In mouse spermatogenesis, differentiating germ line cells initiate\\u000a expression of specific genes at subsequent developmental steps. The\\u000a Calmegin (Clgn) gene is first expressed in meiotic prophase, in primary\\u000a spermatocytes, and encodes a protein that acts as a chaperone. To identify\\u000a testis-specific transcription factors that control expression of the Clgn\\u000a gene in spermatogenesis, we performed a yeast one-hybrid screening with a

Michel Siep; Esther Sleddens-Linkels; Sabine Mulders; Hans van Eenennaam; Evelyne Wassenaar; Cappellen van W. A; Jos Hoogerbrugge; J. Anton Grootegoed; Willy M. Baarends

2004-01-01

66

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

SciTech Connect

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

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

2006-08-01

67

GTF2IRD2 is located in the Williams-Beuren syndrome critical region 7q11.23 and encodes a protein with two TFII-I-like helix-loop-helix repeats  

Microsoft Academic Search

Williams-Beuren syndrome (also known as Williams syndrome) is caused by a deletion of a 1.55- to 1.84-megabase region from chromosome band 7q11.23. GTF2IRD1 and GTF2I, located within this critical region, encode proteins of the TFII-I family with multiple helix-loop-helix domains known as I repeats. In the present work, we characterize a third member, GTF2IRD2, which has sequence and structural similarity

Aleksandr V. Makeyev; Lkhamsuren Erdenechimeg; Ognoon Mungunsukh; Jutta J. Roth; Badam Enkhmandakh; Frank H. Ruddle; Dashzeveg Bayarsaihan

2004-01-01

68

Developmental and evolutionary aspects of the basic helix–loop–helix transcription factors Atonal-like 1 and Achaete-scute homolog 2 in the jellyfish  

Microsoft Academic Search

The close functional link of nerve and muscle cells in neuromuscular units has led to the hypothesis of a common evolutionary origin of both cell types. Jellyfish are well suited to evaluate this theory since they represent the most basal extant organisms featuring both striated muscle and a nervous system. Here we describe the structure and expression of two novel

Katja Seipel; Nathalie Yanze; Volker Schmid

2004-01-01

69

High AN1 variability and interaction with basic helix-loop-helix co-factors related to anthocyanin biosynthesis in potato leaves.  

PubMed

AN1 is a regulatory gene that promotes anthocyanin biosynthesis in potato tubers and encodes a R2R3 MYB transcription factor. However, no clear evidence implicates AN1 in anthocyanin production in leaves, where these pigments might enhance environmental stress tolerance. In our study we found that AN1 displays intraspecific sequence variability in both coding/non-coding regions and in the promoter, and that its expression is associated with high anthocyanin content in leaves of commercial potatoes. Expression analysis provided evidence that leaf pigmentation is associated to AN1 expression and that StJAF13 acts as putative AN1 co-regulator for anthocyanin gene expression in leaves of the red leaf variety 'Magenta Love,' while a concomitant expression of StbHLH1 may contribute to anthocyanin accumulation in leaves of 'Double Fun.' Yeast two-hybrid experiments confirmed that AN1 interacts with StbHLH1 and StJAF13 and the latter interaction was verified and localized in the cell nucleus by bimolecular fluorescence complementation assays. In addition, transgenic tobacco (Nicotiana tabacum) overexpressing a combination of either AN1 with StJAF13 or AN1 with StbHLH1 showed deeper purple pigmentation with respect to AN1 alone. This further confirmed AN1/StJAF13 and AN1/StbHLH1 interactions. Our findings demonstrate that the classical loci identified for potato leaf anthocyanin accumulation correspond to AN1 and may represent an important step to expand our knowledge on the molecular mechanisms underlying anthocyanin biosynthesis in different plant tissues. PMID:25159050

D'Amelia, Vincenzo; Aversano, Riccardo; Batelli, Giorgia; Caruso, Immacolata; Castellano Moreno, Mar; Castro-Sanz, Ana Beatriz; Chiaiese, Pasquale; Fasano, Carlo; Palomba, Francesca; Carputo, Domenico

2014-11-01

70

The basic helix-loop-helix/leucine zipper transcription factor USF2 integrates serum-induced PAI-1 expression and keratinocyte growth.  

PubMed

Plasminogen activator inhibitor type-1 (PAI-1), a major regulator of the plasmin-dependent pericellular proteolytic cascade, is prominently expressed during the tissue response to injury although the factors that impact PAI-1 induction and their role in the repair process are unclear. Kinetic modeling using established biomarkers of cell cycle transit (c-MYC; cyclin D1; cyclin A) in synchronized human (HaCaT) keratinocytes, and previous cytometric assessments, indicated that PAI-1 transcription occurred early after serum-stimulation of quiescent (G0) cells and prior to G1 entry. It was established previously that differential residence of USF family members (USF1?USF2 switch) at the PE2 region E box (CACGTG) characterized the G0 ???G1 transition period and the transcriptional status of the PAI-1 gene. A consensus PE2 E box motif (5'-CACGTG-3') at nucleotides -566 to -561 was required for USF/E box interactions and serum-dependent PAI-1 transcription. Site-directed CG???AT substitution at the two central nucleotides inhibited formation of USF/probe complexes and PAI-1 promoter-driven reporter expression. A dominant-negative USF (A-USF) construct or double-stranded PE2 "decoy" attenuated serum- and TGF-?1-stimulated PAI-1 synthesis. Tet-Off induction of an A-USF insert reduced both PAI-1 and PAI-2 transcripts while increasing the fraction of Ki-67(+) cells. Conversely, overexpression of USF2 or adenoviral-delivery of a PAI-1 vector inhibited HaCaT colony expansion indicating that the USF1???USF2 transition and subsequent PAI-1 transcription are critical events in the epithelial go-or-grow response. Collectively, these data suggest that USF2, and its target gene PAI-1, regulate serum-stimulated keratinocyte growth, and likely the cadence of cell cycle progression in replicatively competent cells as part of the injury repair program. PMID:24905330

Qi, Li; Higgins, Craig E; Higgins, Stephen P; Law, Brian K; Simone, Tessa M; Higgins, Paul J

2014-10-01

71

A novel basic region\\/helix-loop-helix protein binds to a G-box motif CACGTG of the bean seed storage protein ?- phaseolin gene  

Microsoft Academic Search

Expression of the bean seed storage protein ?-phaseolin is under strict developmental control primarily at the level of transcription. A G-box motif CACGTG has been shown to be a major positive cis-acting element of the ?-phaseolin gene and to be recognized by a DNA binding protein from bean seed nuclei. To understand the molecular nature of the G-box-binding protein, we

Yasushi Kawagoe; Norimoto Murai

1996-01-01

72

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

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

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

2014-01-01

73

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

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.

Dawson, S.R.; Turner, D.L.; Weintraub, H.; Parkhurst, S.M. [Fred Hutchinson Cancer Research Center, Seattle, WA (United States)

1995-12-01

74

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

ERIC Educational Resources Information Center

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

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

2003-01-01

75

Cell, Vol. 79, 805-815, December 2, 1994, Copyright 0 1994 by Cell Press Groucho Is Required for Drosophila Neurogenesis,  

E-print Network

is essential for this interaction. We demonstrate that these associations reflect in vivo maternal requirements; Howard and Ingham, 1986; Ish-Horowitz and Pin- chin, 1987). hairy encodes a basic-helix-loop-helix (b

Brent, Roger

76

The role of a Williams-Beuren syndrome-associated helix-loop-helix domain-containing transcription factor in activin\\/nodal signaling  

Microsoft Academic Search

We investigated the regulation of the activin\\/nodal-inducible distal element (DE) of the Xenopus goosecoid (gsc) promoter. On the basis of its interaction with the DE, we isolated a Xenopus homolog of the human Williams-Beuren syndrome critical region 11 (XWBSCR11), and further, show that it interacts with pathway-specific Smad2 and Smad3 in a ligand-dependent manner. Interestingly, we also find that XWBSCR11

Colleen Ring; Souichi Ogata; Lauren Meek; Jihwan Song; Tatsuru Ohta; Kohei Miyazono; Ken W. Y. Cho

2002-01-01

77

p204 Protein Overcomes the Inhibition of Core Binding Factor ?-1–mediated Osteogenic Differentiation by Id Helix-Loop-Helix Proteins  

PubMed Central

Id proteins play important roles in osteogenic differentiation; however, the molecular mechanism remains unknown. In this study, we established that inhibitor of differentiation (Id) proteins, including Id1, Id2, and Id3, associate with core binding factor ?-1 (Cbfa1) to cause diminished transcription of the alkaline phosphatase (ALP) and osteocalcin (OCL) gene, leading to less ALP activity and osteocalcin (OCL) production. Id acts by inhibiting the sequence-specific binding of Cbfa1 to DNA and by decreasing the expression of Cbfa1 in cells undergoing osteogenic differentiation. p204, an interferon-inducible protein that interacts with both Cbfa1 and Id2, overcame the Id2-mediated inhibition of Cbfa1-induced ALP activity and OCL production. We show that 1) p204 disturbed the binding of Id2 to Cbfa1 and enabled Cbfa1 to bind to the promoters of its target genes and 2) that p204 promoted the translocation from nucleus to the cytoplasm and accelerated the degradation of Id2 by ubiquitin–proteasome pathway during osteogenesis. Nucleus export signal (NES) of p204 is required for the p204-enhanced cytoplasmic translocation and degradation of Id2, because a p204 mutant lacking NES lost these activities. Together, Cbfa1, p204, and Id proteins form a regulatory circuit and act in concert to regulate osteoblast differentiation. PMID:18287524

Luan, Yi; Yu, Xiu-Ping; Yang, Ning; Frenkel, Sally; Chen, Lin

2008-01-01

78

Multiscale Simulation of Protein Mediated Membrane Remodeling  

PubMed Central

Proteins interacting with membranes can result in substantial membrane deformations and curvatures. This effect is known in its broadest terms as membrane remodeling. This review article will survey current multiscale simulation methodologies that have been employed to examine protein-mediated membrane remodeling. PMID:19922811

Ayton, Gary S.; Voth, Gregory A.

2009-01-01

79

Development/Plasticity/Repair Regulation of Secretory Protein Expression in Mature Cells  

E-print Network

homeostatic systems. Key words: Drosophila; basic helix-loop-helix; Mist1; dimmed; Atonal; leucokinin; PHM and its regulation. Several members of the Atonal family of basic helix­loop­ helix (bHLH) transcription includes Drosophila Atonal and the vertebrate NeuroD (neuro- genic differentiation),

Hewes, Randall S.

80

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

PubMed

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

Tiller, George R; Garsin, Danielle A

2014-06-19

81

Sense organ identity in the Drosophila antenna is specified by the expression of the proneural gene atonal  

Microsoft Academic Search

We have shown that the basic helix–loop–helix transcription factor Atonal is sufficient for specification of one of the three subsets of olfactory sense organs on the Drosophila antenna. Misexpression of Atonal in all sensory precursors in the antennal disc results in their conversion to coeloconic sensilla. The mechanism by which specific sense organ fate is triggered remains unclear. We have

Dhanisha Jhaveri; Anindya Sen; G. Venugopala Reddy; Veronica Rodrigues

2000-01-01

82

Cellular/Molecular Olig1 and Sox10 Interact Synergistically to Drive Myelin  

E-print Network

Transcription in Oligodendrocytes Huiliang Li,1 Yan Lu,2 Hazel K. Smith,1 and William D. Richardson1 1Wolfson W12 0NN, United Kingdom The oligodendrocyte lineage genes (Olig1/2), encoding basic helix-loop-helix transcription factors, were first identified in screens for master regulators of oligodendrocyte development

Richardson, William D.

83

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

E-print Network

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

Zhou, Yaoqi

84

a patch, it is advantageous for her to lay male-destined eggs if she has only  

E-print Network

spider mite eggs will remain unfertilized then females in poor condition would be predicted to produce.10.049 Fruit Development: New Directions for an Old Pathway A recent study investigating the molecular mechanisms of seed pod shattering has shown that the basic helix-loop-helix (bHLH) proteins INDEHISCENT

Millar, Andrew J.

85

BASICS  

E-print Network

BASICS (Brief Alcohol Screening and Intervention of College Students) is a selective or indicated alcohol abuse prevention program for college students. Program Targets BASICS is aimed at college students 18-24 years old who drink alcohol heavily and have experienced or are at risk for alcohol-related problems such as academic failure, social conflicts, accidents, sexual assault, or violence. The program was not designed to treat alcohol dependence and is unlikely to resolve the disorders of students who are severely alcohol dependent, but can be used for those students in a stepped-care model that provides them with a comprehensive assessment, feedback, advice and referral to specialty care. Program Content BASICS is conducted over the course of two structured interviews and is delivered using motivational interviewing, a counseling modality that is empathetic and accepting rather than confrontational or judgmental. Before or after the first interview, the student completes a self-report questionnaire usually online. From the questionnaire and the assessment interview, information is gathered about the student’s: 1) typical alcohol consumption and peak drinking episodes, 2) beliefs about the drinking habits of other college students 3) number and type of alcohol-related negative consequences, 4) indices of alcohol dependence, 5) family history of alcohol problems, 6) alcohol outcome expectancies, and 7) perceived level of risk for developing a drinking problem. The second interview, which occurs 1-2 weeks after the initial interview, provides the student with personalized feedback about each piece of information gathered in the assessment session. Feedback to the student is accompanied by challenges to myths about alcohol’s effects, ways to reduce future risks associated with alcohol use, a menu of options to assist in making changes and may also include stepped-care options such as a follow-up session or referral to on or off campus mental health and substance abuse treatment services. www.colorado.edu/cspv

unknown authors

86

Molecular evolution of the MyoD family of transcription factors.  

PubMed Central

Myogenesis in skeletal muscle is a cascade of developmental events whose initiation involves the MyoD family of transcription factors. Evolutionary analyses of amino acid sequences of this family of transcriptional activators suggest that the vertebrate genes MyoD1, myf-5, Myog (myogenin), and myf-6 were derived by gene duplications from a single ancestral gene. A common genetic origin predicts some functional redundancy between MyoD1 and myf-5 and between Myog and myf-6. Experimental studies have suggested that these pairs of genes can substitute for each other during myogenesis. Separate analyses of the conserved basic helix-loop-helix and nonconserved flanking elements yield similar branching sequences but show evolutionary change in the basic helix-loop-helix region has occurred at a much slower rate. PMID:7972095

Atchley, W R; Fitch, W M; Bronner-Fraser, M

1994-01-01

87

Arabidopsis CRY2 and ZTL mediate blue-light regulation of the transcription factor CIB1 by distinct mechanisms  

PubMed Central

Plants possess multiple photoreceptors to mediate light regulation of growth and development, but it is not well understood how different photoreceptors coordinate their actions to jointly regulate developmental responses, such as flowering time. In Arabidopsis, the photoexcited cryptochrome 2 interacts with the transcription factor CRYPTOCHROME-INTERACTING basic helix–loop–helix 1 (CIB1) to activate transcription and floral initiation. We show that the CIB1 protein expression is regulated by blue light; CIB1 is highly expressed in plants exposed to blue light, but levels of the CIB1 protein decreases in the absence of blue light. We demonstrate that CIB1 is degraded by the 26S proteasome and that blue light suppresses CIB1 degradation. Surprisingly, although cryptochrome 2 physically interacts with CIB1 in response to blue light, it is not the photoreceptor mediating blue-light suppression of CIB1 degradation. Instead, two of the three light–oxygen–voltage (LOV)-domain photoreceptors, ZEITLUPE and LOV KELCH PROTEIN 2, but not FLAVIN-BINDING KELCH REPEAT 1, are required for the function and blue-light suppression of degradation of CIB1. These results support the hypothesis that the evolutionarily unrelated blue-light receptors, cryptochrome and LOV-domain F-box proteins, mediate blue-light regulation of the same transcription factor by distinct mechanisms. PMID:24101505

Liu, Hongtao; Wang, Qin; Liu, Yawen; Zhao, Xiaoying; Imaizumi, Takato; Somers, David E.; Tobin, Elaine M.; Lin, Chentao

2013-01-01

88

Up-regulation of hypoxia-inducible factors HIF-1? and HIF-2? under normoxic conditions in renal carcinoma cells by von Hippel-Lindau tumor suppressor gene loss of function  

Microsoft Academic Search

Hypoxia induces transcription of a range of physiologically important genes including erythropoietin and vascular endothelial growth factor. The transcriptional activation is mediated by the hypoxia-inducible factor-1 (HIF-1), a heterodimeric member of the basic helix–loop–helix PAS family, composed of ? and ? subunits. HIF-1? shares 48 per cent identity with the recently identified HIF-2? protein that is also stimulated by hypoxia.

Marion Krieg; Richard Haas; Hiltrud Brauch; Till Acker; Ingo Flamme; Karl H Plate

2000-01-01

89

Transcription of a zebrafish gene of the hairy-Enhancer of split family delineates the midbrain anlage in the neural plate  

Microsoft Academic Search

her5 encodes a basic helix-loop-helix (bHLH) protein with all features characteristic of the Drosophila hairy-E(spl) family. her5 is expressed in a band of cells within the neural anlage from about 90% epiboly on to at least 36 h postfertilization (hpf).\\u000a After completion of brain morphogenesis, her5-expressing cells are located in the caudal region of the midbrain, at the boundary with

Marcus Müller; Elisabeth von Weizsäcker; José A. Campos-Ortega

1996-01-01

90

Structure, function, and dynamics of the dimerization and DNA-binding domain of oncogenic transcription factor v-Myc1  

Microsoft Academic Search

The protein product (c-Myc) of the protooncogene c-myc is a transcrip- tional regulator playing a key role in cellular growth, differentiation, and apoptosis. Deregulated myc genes, like the transduced retroviral v-myc allele, are oncogenic and cause cell transformation. The C-terminal bHLHZip domain of v-Myc, encompassing protein dimerization (helix- loop-helix, leucine zipper) and DNA contact (basic region) surfaces, was expressed in

Wolfgang Fieber; Martin L. Schneider; Theresia Matt; Bernhard Kräutler; Robert Konrat; Klaus Bister

2001-01-01

91

SREBP Coordinates Iron and Ergosterol Homeostasis to Mediate Triazole Drug and Hypoxia Responses in the Human Fungal Pathogen Aspergillus fumigatus  

Microsoft Academic Search

Sterol regulatory element binding proteins (SREBPs) are a class of basic helix-loop-helix transcription factors that regulate diverse cellular responses in eukaryotes. Adding to the recognized importance of SREBPs in human health, SREBPs in the human fungal pathogens Cryptococcus neoformans and Aspergillus fumigatus are required for fungal virulence and susceptibility to triazole antifungal drugs. To date, the exact mechanism(s) behind the

Michael Blatzer; Bridget M. Barker; Sven D. Willger; Nicola Beckmann; Sara J. Blosser; Elizabeth J. Cornish; Aurelien Mazurie; Nora Grahl; Hubertus Haas; Robert A. Cramer

2011-01-01

92

Twist2 contributes to breast cancer progression by promoting an epithelial–mesenchymal transition and cancer stem-like cell self-renewal  

Microsoft Academic Search

The epithelial to mesenchymal transition (EMT) is a highly conserved cellular programme that has an important role in normal embryogenesis and in cancer invasion and metastasis. We report here that Twist2, a tissue-specific basic helix-loop-helix transcription factor, is overexpressed in human breast cancers and lymph node metastases. In mammary epithelial cells and breast cancer cells, ectopic overexpression of Twist2 results

X Fang; Y Cai; J Liu; Z Wang; Q Wu; Z Zhang; C J Yang; L Yuan; G Ouyang

2011-01-01

93

Expression of Id1 mRNA and Protein in the Post-Ischemic Regenerating Rat Kidney  

Microsoft Academic Search

The basic helix-loop-helix (bHLH) class of proteins are of major importance in controlling tissue-specific gene expression. The actions of the bHLH proteins are inhibited by a related class of proteins, inhibitors of differentiation (Id). We have studied the expression of one of these latter proteins, Id-1, in the normal and post-ischemic regenerating rat kidney by immunocytochemistry, Western blot and RNase

Göran L. Matejka; Maria Thornemo; Annika Kernholt; Anders Lindahl

1998-01-01

94

Inhibition of Tcf3 Binding by I-mfa Domain Proteins  

Microsoft Academic Search

We have determined that I-mfa, an inhibitor of several basic helix-loop-helix (bHLH) proteins, and XIC, a Xenopus ortholog of human I-mf domain-containing protein that shares a highly conserved cysteine-rich C- terminal domain with I-mfa, inhibit the activity and DNA binding of the HMG box transcription factor XTcf3. Ecto- pic expression of I-mfa or XIC in early Xenopus embryos inhibited dorsal

LAUREN SNIDER; HILARY THIRLWELL; JEFFREY R. MILLER; RANDALL T. MOON; MARK GROUDINE; STEPHEN J. TAPSCOTT

2001-01-01

95

A New Turn (or Two) for Twist  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Two reports in this week's issue of Science [Baylies (p. 1481) and Spicer (p. 1476)] describe new functions in muscle development for the gene twist, a basic helix-loop-helix transcription factor. In his Perspective, Michelson explains how these two seemingly contradictory functions of twist (specification of mesodermal cell fate in fruit flies and inhibition of muscle differentiation in vertebrates) can be reconciled.

Alan M. Michelson (Brigham and Women's Hospital;Howard Hughes Medical Institute and the Department of Medicine)

1996-06-07

96

A comparison of Twist and E-cadherin protein expression in primary non-small-cell lung carcinoma and corresponding metastases  

Microsoft Academic Search

Objective: The metastasis of solid tumors is directly or indirectly responsible for most cancer-related deaths. It has already been known that in non-small-cell lung carcinoma cells, up-regulation of Twist (a highly conserved basic helix-loop-helix transcription factor) can promote epithelial–mesenchymal transition through down-regulation of E-cadherin. The main aim of this study was to determine whether the expression of Twist and E-cadherin

Guanghui Wang; Wei Dong; Hongchang Shen; Xueru Mu; Zhenxiang Li; Xiaoyan Lin; Ying Liu; Jiajun Du

2011-01-01

97

Achaete-scute homolog-1 linked to remodeling and preneoplasia of pulmonary epithelium  

Microsoft Academic Search

The basic helix–loop–helix protein achaete-scute homolog-1 (ASH1) is involved in lung neuroendocrine (NE) differentiation and tumor promotion in SV40 transgenic mice. Constitutive expression of human ASH-1 (hASH1) in mouse lung results in hyperplasia and remodeling that mimics bronchiolization of alveoli (BOA), a potentially premalignant lesion of human lung carcinomas. We now show that this is due to sustained cellular proliferation

Xiao-Yang Wang; El Habib Dakir; Xu Naizhen; Sandra M Jensen-Taubman; Francesco J DeMayo; R Ilona Linnoila

2007-01-01

98

Absence of Yolk sac Hematopoiesis from Mice with a Targeted Disruption of the scl Gene  

Microsoft Academic Search

The scl gene encodes a basic-helix-loop-helix transcription factor which was identified through its involvement in chromosomal translocations in T-cell leukemia. To elucidate its physiological role, scl was targeted in embryonic stem cells. Mice heterozygous for the scl null mutation were intercrossed and their offspring were genotyped. Homozygous mutant (scl-\\/-) pups were not detected in newborn litters, and analysis at earlier

Lorraine Robb; Ian Lyons; Ruili Li; Lynne Hartley; Frank Kontgen; Richard P. Harvey; Donald Metcalf; C. Glenn Begley

1995-01-01

99

Evolution of proneural atonal expression during distinct regulatory phases in the developing Drosophila eye  

Microsoft Academic Search

Background Receptors of the Notch family affect the determination of many cell types. In the Drosophila eye, Notch antagonises the basic helix–loop–helix (bHLH) protein atonal, which is required for R8 photoreceptor determination. Similar antagonism between Notch and proneural bHLH proteins regulates most neural cell determination, however, it is uncertain whether the mechanisms are similar in all cases. Here, we have

Nicholas E. Baker; Sung Yu; Doreen Han

1996-01-01

100

Evolutionary conservation of sequence and expression of the bHLH protein Atonal suggests a conserved role in neurogenesis  

Microsoft Academic Search

atonal is a Drosophila proneural gene that belongs to the family of basic helix-loop-helix (bHLH)- containing proteins. It is expressed in the chordotonal organs and photoreceptor cells, and flies that lack Atonal protein are ataxic and blind. Here we report the cloning of atonal homologs from red flour beetle, puffer fish, chicken, mouse, and human. The bHLH domain is conserved

Nissim Ben-Arie; Alanna E. McCall; Scott Berkman; Gregor Eichele; Hugo J. Bellen; Huda Y. Zoghbi

1996-01-01

101

Negative Regulation of atonal in Proneural Cluster Formation of Drosophila R8 Photoreceptors  

Microsoft Academic Search

atonal (ato) encodes a basic helix-loop-helix protein and is required for the specification of R8 photoreceptor cells in Drosophila. In the eye imaginal discs, expression of Ato protein is initially in a dorsoventral stripe of cells anterior to the morphogenetic furrow (MF). In the MF, this stripe expression is resolved into regularly spaced clusters of Ato-positive cells, the proneural clusters,

Chien-Kuo Chen; Cheng-Ting Chien

1999-01-01

102

Genetic Mapping of Four Mouse bHLH Genes Related to DrosophilaProneural Gene atonal  

Microsoft Academic Search

It has been shown that mammalian neurogenesis is partly controlled by multiple basic helix–loop–helix (bHLH) genes, as inDrosophila.Recently, mouse homologs ofDrosophila atonal,a proneural gene encoding a bHLH protein required for chordotonal organ and photoreceptor development, have been characterized to obtain further insights into the molecular nature of mammalian neurogenesis. Here, to assess their potential involvement in genetic neural disorders, we

Fumiaki Isaka; Chikara Shimizu; Shigetada Nakanishi; Ryoichiro Kageyama

1996-01-01

103

Atonal homolog 1 Is a Tumor Suppressor Gene  

Microsoft Academic Search

Colon cancer accounts for more than 10% of all cancer deaths annually. Our genetic evidence from Drosophila and previous in vitro studies of mammalian Atonal homolog 1 (Atoh1, also called Math1 or Hath1) suggest an anti- oncogenic function for the Atonal group of proneural basic helix-loop-helix transcription factors. We asked whether mouse Atoh1 and human ATOH1 act as tumor suppressor

Wouter Bossuyt; Avedis Kazanjian; Natalie De Geest; Sofie Van Kelst; Gert De Hertogh; Karel Geboes; Greg P. Boivin; Judith Luciani; Francois Fuks; Marinee Chuah; Thierry VandenDriessche; Peter Marynen; Jan Cools; Noah F. Shroyer; Bassem A. Hassan

2009-01-01

104

Regulation of hepatocyte proliferation by ligand-activated aryl hydrocarbon receptor  

Microsoft Academic Search

Ligands of the aryl hydrocarbon receptor (AhR), a basic helix-loop-helix transcription factor, induce hepatocellular carcinomas and alter hepatocyte proliferation in rodents. In the studies described in this thesis, primary hepatocytes and the rat hepatoma 5L cell line were used as models to characterize the actions of TCDD on hepatocyte proliferation. TCDD inhibited DNA synthesis in primary hepatocytes and 5L cells,

Dennet Richard Hushka

1996-01-01

105

Twist1 dimer selection regulates cranial suture patterning and fusion  

Microsoft Academic Search

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

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

2006-01-01

106

WBSCR14, a gene mapping to the Williams-Beuren syndrome deleted region, is a new member of the Mlx transcription factor network  

Microsoft Academic Search

Williams-Beuren syndrome (WBS) is a develop- mental disorder associated with haploinsufficiency of multiple genes at 7q11.23. Here, we report the functional characterization of WBS critical region gene 14 (WBSCR14), a gene contained in the WBS commonly deleted region. It encodes a basic-helix- loop-helix leucine zipper (bHLHZip) transcription factor of the Myc\\/Max\\/Mad superfamily. WBSCR14 is expressed in multiple tissues, including regions

Stefano Cairo; Giuseppe Merla; Fabrizia Urbinati; Andrea Ballabio; Alexandre Reymond

2001-01-01

107

Overexpression of a Zebrafish ARNT2-like Factor Represses CYP1A Transcription in ZLE Cells  

Microsoft Academic Search

:   Aryl hydrocarbon receptor nuclear translocator (ARNT) factors belong to a novel basic-helix-loop-helix–PAS (bHLH-PAS) transcription\\u000a factor family that controls a variety of physiological and developmental processes. In a previous study, we obtained a partial\\u000a complementary DNA fragment of an ARNT2-like factor from zebrafish embryo, liver, and other tissues by reverse transcription–polymerase\\u000a chain reaction. In an effort to characterize the function

Wen-Der Wang; Jun-Chyi Wu; Hwei-Jan Hsu; Zwe-Ling Kong; Chin-Hwa Hu

2000-01-01

108

Id1 overexpression induces tetraploidization and multiple abnormal mitotic phenotypes by modulating aurora A  

Microsoft Academic Search

The basic helix-loop-helix transcription factor, Id1, was shown to induce tetraploidy in telomerase-immortalized nasopharyngeal epithelial cells in this study. Using both transient and stable Id1-expressing cell models, multiple mitotic aberrations were detected, including centrosome amplification, binucleation, spindle defects, and microtubule perturbation. Many of these abnormal phenotypes have previously been reported in cells overexpressing Aurora A. Further experiments showed that Id1

Cornelia Man; Jack Rosa; Y. L. Yip; Annie Lai-Man Cheung; Yok-Lam Kwong; Stephen J. Doxsey; Sai Wah Tsao

2008-01-01

109

Determination of the binding constants of the centromere protein Cbf1 to all 16 centromere DNAs of Saccharomyces cerevisiae  

Microsoft Academic Search

Cbf1p is a Saccharomyces cerevisiae chromatin protein belonging to the basic region helix-loop-helix leucine zipper (bHLHzip) family of DNA binding proteins. Cbf1p binds to a conserved element in the 5'-flanking region of methionine biosynthetic genes and to centromere DNA element I (CDEI) of S.cerevisiae centromeric DNA. We have determined the apparent equilibrium dissociation constants of Cbf1p binding to all 16

Gerhard Wieland; Peter Hemmerich; Marianne Koch; Tanja Stoyan; Johannes Hegemann; Stephan Diekmann

2001-01-01

110

Sn, a maize bHLH gene, modulates anthocyanin and condensed tannin pathways in Lotus corniculatus  

Microsoft Academic Search

Anthocyanins and condensed tannins are major fla- vonoid end-products in higher plants. While the transactivation of anthocyanins by basic helix-loop- helix (bHLH) transcription factors is well docu- mented, 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

Mark Paske Robbins; Francesco Paolocci; John-Wayne Hughes; Valentina Turchetti; Gordon Allison; Sergio Arcioni; Phillip Morris; Francesco Damiani

2003-01-01

111

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

Microsoft Academic Search

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

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

2000-01-01

112

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

Microsoft Academic Search

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

Qiao Zhou; Gloria Choi; David J. Anderson

2001-01-01

113

Phylogenetic Footprinting Analysis in the Upstream Regulatory Regions of the Drosophila Enhancer of split Genes  

Microsoft Academic Search

During Drosophila development Suppressor of Hairless ½Su(H)? -dependent Notch activation upregu- lates transcription of the Enhancer of split-Complex ½E(spl)-Cgenes. Drosophila melanogaster E(spl) genes share common transcription regulators including binding sites for Su(H), proneural, and E(spl) basic-helix-loop- helix (bHLH) proteins. However, the expression patterns of E(spl) genes during development suggest that additional factors are involved. To better understand regulators responsible for

Morgan L. Maeder; Benjamin J. Polansky; Bryanne E. Robson; Deborah A. Eastman

2007-01-01

114

The hsp90 Chaperone Complex Regulates Intracellular Localization of the Dioxin Receptor  

Microsoft Academic Search

The molecular chaperone complex hsp90-p23 interacts with the dioxin receptor, a ligand-dependent basic helix-loop-helix (bHLH)\\/Per-Arnt-Sim domain transcription factor. Whereas biochemical and genetic evidence indicates that hsp90 is important for maintenance of a high-affinity ligand binding conformation of the dioxin receptor, the role of hsp90-associated proteins in regulation of the dioxin receptor function remains unclear. Here we demonstrate that the integrity

ARUNAS KAZLAUSKAS; SARA SUNDSTROM; LORENZ POELLINGER; INGEMAR PONGRATZ

2001-01-01

115

Transcription of MyoD and myogenin in the non-contractile electrogenic cells of the weakly electric fish, Sternopygus macrurus  

Microsoft Academic Search

The MyoD family of basic helix-loop-helix (bHLH) myogenic regulatory factors (MRFs) are transcriptional activators of skeletal muscle gene expression and are pivotal in inducing the full myogenic program. The expression of these factors after muscle differentiation is complete and the mechanism by which they modulate (or maintain) the muscle phenotype is less well understood. The myogenically derived electric organ (EO)

Jung A. Kim; Colleen B. Jonsson; Tiffany Calderone; Graciela A. Unguez

2004-01-01

116

Increased risk for developmental delay in Saethre-Chotzen syndrome is associated with TWIST deletions: an improved strategy for TWIST mutation screening  

Microsoft Academic Search

The majority of patients with Saethre-Chotzen syndrome have mutations in the TWIST gene, which codes for a basic helix-loop-helix transcription factor. Of the genetic alterations identified in TWIST, nonsense mutations, frameshifts secondary to small deletions or insertions, and large deletions implicate haploinsufficiency as the pathogenic mechanism. We identified three novel intragenic mutations and six deletions in our patients by using

Juanliang Cai; Barbara K. Goodman; Ankita S. Patel; John B. Mulliken; Lionel Van Maldergem; George E. Hoganson; William A. Paznekas; Ziva Ben-Neriah; Ruth Sheffer; Michael L. Cunningham; Donna L. Daentl; EthylinWang Jabs

2003-01-01

117

Snail, Zeb and bHLH factors in tumour progression: an alliance against the epithelial phenotype?  

Microsoft Academic Search

The molecular mechanisms that underlie tumour progression are still poorly understood, but recently our knowledge of particular aspects of some of these processes has increased. Specifically, the identification of Snail, ZEB and some basic helix-loop-helix (bHLH) factors as inducers of epithelial–mesenchymal transition (EMT) and potent repressors of E-cadherin expression has opened new avenues of research with potential clinical implications.

Héctor Peinado; David Olmeda; Amparo Cano

2007-01-01

118

NGF-dependent and tissue-specific transcription of vgf is regulated by a CREB–p300 and bHLH factor interaction  

Microsoft Academic Search

Neurotrophins support neuronal survival, development, and plasticity through processes requiring gene expression. We studied how vgf target gene transcription is mediated by a critical promoter region containing E-box, CCAAT and cAMP response element (CRE) sites. The p300 acetylase was present in two distinct protein complexes bound to this region. One complex, containing HEB (ubiquitous basic helix–loop–helix (bHLH)), bound the promoter

Georgia Mandolesi; Silvia Gargano; Maria Pennuto; Barbara Illi; Rosa Molfetta; Laura Soucek; Laura Mosca; Andrea Levi; Richard Jucker; Sergio Nasi

2002-01-01

119

A cellular factor stimulates the DNA-binding activity of MyoD and E47.  

PubMed Central

We show that mixing purified MyoD and E47 proteins results in heterodimers that fail to bind DNA, even though MyoD and E47 homodimers can bind DNA efficiently. Addition of cell extracts or a specific fraction from a cell extract enables the heterodimer to bind DNA, but components in this fraction fail to enter the DNA complex. The activity is sensitive to heat and protease and is not ATP-dependent. The activity functions on E47 and MyoD homodimers and can stimulate DNA binding of the basic-helix-loop-helix region of MyoD. The effectiveness of the activity, for MyoD homodimers, depends on the exact DNA sequence of the binding site. Our results suggest that specific factors in the cell might control the DNA-binding properties of helix-loop-helix proteins. Images Fig. 2 Fig. 3 Fig. 1 Fig. 4 Fig. 5 PMID:8393567

Thayer, M J; Weintraub, H

1993-01-01

120

Prostacyclin-induced hyperthermia - Implication of a protein mediator  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

121

ATG proteins mediate efferocytosis and suppress inflammation in mammary involution.  

PubMed

Involution is the process of post-lactational mammary gland regression to quiescence and it involves secretory epithelial cell death, stroma remodeling and gland repopulation by adipocytes. Though reportedly accompanying apoptosis, the role of autophagy in involution has not yet been determined. We now report that autophagy-related (ATG) proteins mediate dead cell clearance and suppress inflammation during mammary involution. In vivo, Becn1(+/-) and Atg7-deficient mammary epithelial cells (MECs) produced 'competent' apoptotic bodies, but were defective phagocytes in association with reduced expression of the MERTK and ITGB5 receptors, thus pointing to defective apoptotic body engulfment. Atg-deficient tissues exhibited higher levels of involution-associated inflammation, which could be indicative of a tumor-modulating microenvironment, and developed ductal ectasia, a manifestation of deregulated post-involution gland remodeling. In vitro, ATG (BECN1 or ATG7) knockdown compromised MEC-mediated apoptotic body clearance in association with decreased RAC1 activation, thus confirming that, in addition to the defective phagocytic processing reported by other studies, ATG protein defects also impair dead cell engulfment. Using two different mouse models with mammary gland-associated Atg deficiencies, our studies shed light on the essential role of ATG proteins in MEC-mediated efferocytosis during mammary involution and provide novel insights into this important developmental process. This work also raises the possibility that a regulatory feedback loop exists, by which the efficacy of phagocytic cargo processing in turn regulates the rate of engulfment and ultimately determines the kinetics of phagocytosis and dead cell clearance. PMID:23380905

Teplova, Irina; Lozy, Fred; Price, Sandy; Singh, Sukhwinder; Barnard, Nicola; Cardiff, Robert D; Birge, Raymond B; Karantza, Vassiliki

2013-04-01

122

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

E-print Network

in a DNA-stimulated manner (Shiba et al., 1991; Mu¨ller et al., 1993b; Mitchell & West, 1994; MarrioneAllosteric Effects of RuvA Protein, ATP, and DNA on RuvB Protein-Mediated ATP Hydrolysis Paul E ABSTRACT: A detailed characterization of RuvB protein-mediated ATP hydrolysis in the presence of Ruv

Cox, Michael M.

123

Overexpression of transcription factor ZmPTF1 improves low phosphate tolerance of maize by regulating carbon metabolism and root growth  

Microsoft Academic Search

A bHLH (basic helix-loop-helix domain) transcription factor involved in tolerance to Pi starvation was cloned from Zea mays with an RT-PCR coupled RACE approach and named ZmPTF1. ZmPTF1 encoded a putative protein of 481 amino acids that had identity with OsPTF1 in basic region. Real-time RT-PCR revealed that\\u000a ZmPTF1 was quickly and significantly up-regulated in the root under phosphate starvation

Zhaoxia LiQiang; Qiang Gao; Yazheng Liu; Chunmei He; Xinrui Zhang; Juren Zhang

2011-01-01

124

Calcium binding protein-mediated regulation of voltage-gated calcium channels linked to human diseases  

Microsoft Academic Search

Calcium ion entry through voltage-gated calcium channels is essential for cellular signalling in a wide variety of cells and multiple physiological processes. Perturbations of voltage-gated calcium channel function can lead to pathophysiological consequences. Calcium binding proteins serve as calcium sensors and regulate the calcium channel properties via feedback mechanisms. This review highlights the current evidences of calcium binding protein-mediated channel

Nasrin Nejatbakhsh; Zhong-ping Feng

2011-01-01

125

XATH-1,a Vertebrate Homolog of Drosophila atonal,Induces Neuronal Differentiation within Ectodermal Progenitors  

Microsoft Academic Search

XATH-1,a basic\\/helix-loop-helix transcription factor and a homolog ofDrosophila atonaland mammalianMATH-1,is expressed specifically in the dorsal hindbrain duringXenopusneural development. In order to investigate the role ofXATH-1in the neuronal differentiation process, we have examined the effects ofXATH-1overexpression duringXenopusdevelopment.XATH-1induces the expression of neuronal differentiation markers, such asN-tubulin,within the neural plate as well as within nonneural ectodermal progenitor populations, resulting in the appearance of

Peter Kim; Amy W. Helms; Jane E. Johnson; Kathryn Zimmerman

1997-01-01

126

The "Sharp” blade against HIF-mediated metastasis  

PubMed Central

Hypoxia-inducible factors (HIFs) control cellular adaptation to oxygen deprivation. Cancer cells engage HIFs to sustain their growth in adverse conditions, thus promoting a cellular reprograming that includes metabolism, proliferation, survival and mobility. HIFs overexpression in human cancer biopsies correlates with high metastasis and mortality. A recent report has elucidated a novel mechanism for HIFs regulation in triple-negative breast cancer. Specifically, the basic helix-loop-helix (bHLH), Sharp-1, serves HIF1? to the proteasome and promotes its O2-indendpendet degradation, counteracting HIF-mediated metastasis. These findings shed light on how HIFs are manipulated during cancer pathogenesis. PMID:23187809

Amelio, Ivano; Melino, Gerry

2012-01-01

127

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

E-print Network

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

K. G. Petrosyan; Chin-Kun Hu

2009-12-21

128

Achaete-scute homologue-1 (ASH1) stimulates migration of lung cancer cells through Cdk5/p35 pathway.  

PubMed

Our previous data suggested that the human basic helix-loop-helix transcription factor achaete-scute homologue-1 (hASH1) may stimulate both proliferation and migration in the lung. In the CNS, cyclin-dependent kinase 5 (Cdk5) and its activator p35 are important for neuronal migration that is regulated by basic helix-loop-helix transcription factors. Cdk5/p35 may also play a role in carcinogenesis. In this study, we found that the neuronal activator p35 was commonly expressed in primary human lung cancers. Cdk5 and p35 were also expressed by several human lung cancer cell lines and coupled with migration and invasion. When the kinase activity was inhibited by the Cdk5 inhibitor roscovitine or dominant-negative (dn) Cdk5, the migration of lung cancer cells was reduced. In neuroendocrine cells expressing hASH1, such as a pulmonary carcinoid cell line, knocking down the gene expression by short hairpin RNA reduced the levels of Cdk5/p35, nuclear p35 protein, and migration. Furthermore, expression of hASH1 in lung adenocarcinoma cells normally lacking hASH1 increased p35/Cdk5 activity and enhanced cellular migration. We were also able to show that p35 was a direct target for hASH1. In conclusion, induction of Cdk5 activity is a novel mechanism through which hASH1 may regulate migration in lung carcinogenesis. PMID:22696682

Demelash, Abeba; Rudrabhatla, Parvathi; Pant, Harish C; Wang, Xiaoyang; Amin, Niranjana D; McWhite, Claire D; Naizhen, Xu; Linnoila, R Ilona

2012-08-01

129

Achaete-scute homologue-1 (ASH1) stimulates migration of lung cancer cells through Cdk5/p35 pathway  

PubMed Central

Our previous data suggested that the human basic helix–loop–helix transcription factor achaete-scute homologue-1 (hASH1) may stimulate both proliferation and migration in the lung. In the CNS, cyclin-dependent kinase 5 (Cdk5) and its activator p35 are important for neuronal migration that is regulated by basic helix–loop–helix transcription factors. Cdk5/p35 may also play a role in carcinogenesis. In this study, we found that the neuronal activator p35 was commonly expressed in primary human lung cancers. Cdk5 and p35 were also expressed by several human lung cancer cell lines and coupled with migration and invasion. When the kinase activity was inhibited by the Cdk5 inhibitor roscovitine or dominant-negative (dn) Cdk5, the migration of lung cancer cells was reduced. In neuroendocrine cells expressing hASH1, such as a pulmonary carcinoid cell line, knocking down the gene expression by short hairpin RNA reduced the levels of Cdk5/p35, nuclear p35 protein, and migration. Furthermore, expression of hASH1 in lung adenocarcinoma cells normally lacking hASH1 increased p35/Cdk5 activity and enhanced cellular migration. We were also able to show that p35 was a direct target for hASH1. In conclusion, induction of Cdk5 activity is a novel mechanism through which hASH1 may regulate migration in lung carcinogenesis. PMID:22696682

Demelash, Abeba; Rudrabhatla, Parvathi; Pant, Harish C.; Wang, Xiaoyang; Amin, Niranjana D.; McWhite, Claire D.; Naizhen, Xu; Linnoila, R. Ilona

2012-01-01

130

Initial size and dynamics of viral fusion pores are a function of the fusion protein mediating membrane fusion  

Microsoft Academic Search

Background information. Protein-mediated merger of biological membranes, membrane fusion, is an important process. To investigate the role of fusogenic proteins in the initial size and dynamics of the fusion pore (a narrow aqueous pathway, which widens to finalize membrane fusion), two different fusion proteins expressed in the same cell line were investigated: the major glycoprotein of baculovirus Autographa californica (GP64)

Ilya Plonsky; Afshin Rashtian; Joshua Zimmerberg

2008-01-01

131

Analysis of the DNA-binding and dimerization activities of Neurospora crassa transcription factor NUC-1.  

PubMed Central

NUC-1, a positive regulatory protein of Neurospora crassa, controls the expression of several unlinked target genes involved in phosphorus acquisition. The carboxy-terminal end of the NUC-1 protein has sequence similarity to the helix-loop-helix family of transcription factors. Bacterially expressed and in vitro-synthesized proteins, which consist of the carboxy-terminal portion of NUC-1, bind specifically to upstream sequences of two of its target genes, pho2+ and pho-4+. These upstream sequences contain the core sequence, CACGTG, a target for many helix-loop-helix proteins. A large loop region (47 amino acids) separates the helix I and helix II domains. Mutations and deletion within the loop region did not interfere with the in vitro or in vivo functions of the protein. Immediately carboxy-proximal to the helix II domain, the NUC-1 protein contains an atypical zipper domain which is essential for function. This domain consists of a heptad repeat of alanine and methionine rather than leucine residues. Analysis of mutant NUC-1 proteins suggests that the helix II and the zipper domains are essential for the protein dimerization, whereas the basic and the helix I domains are involved in DNA binding. The helix I domain, even though likely to participate in dimer formation while NUC-1 is bound to DNA, is not essential for in vitro dimerization. Images PMID:7969122

Peleg, Y; Metzenberg, R L

1994-01-01

132

Phosphorylated Olig1 Localizes to the Cytosol of Oligodendrocytes and Promotes Membrane Expansion and Maturation  

PubMed Central

Oligodendroglial cells undergo rapid transcriptional and dynamic morphological transformation in order to effectively myelinate neuronal axons. Olig1, a basic helix-loop-helix transcription factor, functions to promote the transcription of myelin-specific genes and promotes differentiation and (re)myelination. While the role for nuclear Olig1 is well established, the function for cytoplasmic Olig1 remains uncertain. We observe that translocation of Olig1 into the cytosol highly correlates with differentiation of oligodendrocytes both in vivo and in vitro. By enforcing expression of a nuclear-specific form of Olig1 into OPCs in a null-Olig1 background, we demonstrate that nuclear Olig1 is sufficient to facilitate MBP expression, but with greatly diminished membrane volume and area. We demonstrate that serine 138 in the helix-loop-helix domain of Olig1 is phosphorylated and that this form resides in the cytosol. Mutating serine 138 to alanine restricts Olig1 to the nucleus, facilitating MBP expression but limiting membrane expansion. However, a serine to aspartic acid mutation results in the cytoplasmic localization of Olig1 enhancing membrane expansion. Our results suggest a novel role for a phosphorylated cytosolic Olig1 in membrane expansion and maturation of oligodendrocytes. PMID:22639060

Niu, Jianqin; Mei, Feng; Wang, Lingyun; Liu, Shubao; Tian, Yanping; Mo, Wei; Li, Hongli; Lu, Q. Richard; Xiao, Lan

2013-01-01

133

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

PubMed

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 ? family members are the major nuclear import receptors for E47. However, inhibition of importin ? 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 ? independent but importin ?1 dependent. In primary neurons, localization of endogenous E47 was not affected by importin ? inhibition, suggesting that neuronal E47 could be imported into the nucleus as a heterodimer with NeuroD1 by using importin ?1 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

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

2011-10-01

134

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

PubMed Central

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

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

2010-01-01

135

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

PubMed Central

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

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

2014-01-01

136

Basic model Basic model  

E-print Network

Spearman's (1904) seminal paper on the American Journal of Psychology entitled "General Inteligente, British Journal of Mathematical and Statistical Psychology, 48, 211-220. 3 / 66 #12;Early days Basic model that Spearman invented factor analysis but his almost exclusive concern with the notion of a general factor

Liu, I-Shih

137

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

SciTech Connect

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.

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

1987-08-25

138

Divergent effects of rosiglitazone on protein-mediated fatty acid uptake in adipose and in muscle tissues of Zucker rats  

Microsoft Academic Search

Thiazolidinediones (TZDs) increase tissue insulin sensitivity in diabetes. Here, we hypothesize that, in adipose tissue, skeletal muscle, and heart, alterations in protein- mediated FA uptake are involved in the effect of TZDs. As a model, we used obese Zucker rats, orally treated for 16 days with 5 mg rosiglitazone (Rgz)\\/kg body mass\\/day. In adipose tissue from Rgz-treated rats, FA uptake

S. L. M. Coort; W. A. Coumans; A. Bonen; G. J. van der Vusse; J. F. C. Glatz; J. J. F. P. Luiken

2005-01-01

139

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

PubMed Central

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

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

1985-01-01

140

Basic Stamp  

NSDL National Science Digital Library

This site from Parallax, Inc. gives some information about basic stamp microcontrollers. A Basic-Stamp microcontroller is a single-board computer. Parallax makes a variety of controllers; the BASIC Stamp II uses a PIC16C57microchip.

2012-10-12

141

Basic Warehousing.  

ERIC Educational Resources Information Center

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…

Marine Corps Inst., Washington, DC.

142

Basic Equality  

Microsoft Academic Search

This is a three-part study and defense of the idea of basic human equality. (This is the idea that humans are basically one another's equals, as opposed to more derivative theories of the dimensions in which we ought to be equal or the particular implications that equality might have for public policy.) Part (1) of the paper examines the very

Jeremy Waldron

2008-01-01

143

Basic HTML  

NSDL National Science Digital Library

Although most web designers use an editor, it is a good idea to have a working knowledge of HTML code. It is useful to be able to go into the code and make adjustments that an editor will not do. knowing HTML will give you more control over the look and function of your web site. Remember that this is just the basics but will provide you with the tools to design great web sites. Assignment Instructions: Go through the HTML Goodies Primers. You will create some basic web pages in these primers. E-mail your instructor each primer assignment at tami.warnick@cmacademy.org Primer 1: Basic HTML: Introduction Instructions: Read through the primer and then send your instructor a breif summary of what you learned. Primer 2: Learn the Basic HTML Tags! Instructions: After ...

Warnick, Mrs.

2009-12-04

144

Basic Finance  

NASA Technical Reports Server (NTRS)

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.

Vittek, J. F.

1972-01-01

145

The Basics  

ERIC Educational Resources Information Center

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

Indrisano, Roselmina; And Others

1976-01-01

146

Energy Basics  

NSDL National Science Digital Library

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

Office Of Educational Partnerships

147

Evidence for the Coupling of ATP Hydrolysis to the Final (Extension) Phase of RecA Protein-mediated DNA Strand Exchange*  

E-print Network

Evidence for the Coupling of ATP Hydrolysis to the Final (Extension) Phase of RecA Protein-mediated DNA Strand Exchange* (Received for publication, February 9, 1995, and in revised form, December 23-Madison, Madison, Wisconsin 53706 RecA protein promotes a limited DNA strand ex- change reaction, without ATP

Cox, Michael M.

148

Network theory inspired analysis of time-resolved expression data reveals key players guiding P. patens stem cell development.  

PubMed

Transcription factors (TFs) often trigger developmental decisions, yet, their transcripts are often only moderately regulated and thus not easily detected by conventional statistics on expression data. Here we present a method that allows to determine such genes based on trajectory analysis of time-resolved transcriptome data. As a proof of principle, we have analysed apical stem cells of filamentous moss (P. patens) protonemata that develop from leaflets upon their detachment from the plant. By our novel correlation analysis of the post detachment transcriptome kinetics we predict five out of 1,058 TFs to be involved in the signaling leading to the establishment of pluripotency. Among the predicted regulators is the basic helix loop helix TF PpRSL1, which we show to be involved in the establishment of apical stem cells in P. patens. Our methodology is expected to aid analysis of key players of developmental decisions in complex plant and animal systems. PMID:23637751

Busch, Hauke; Boerries, Melanie; Bao, Jie; Hanke, Sebastian T; Hiss, Manuel; Tiko, Theodhor; Rensing, Stefan A

2013-01-01

149

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

PubMed Central

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

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

2009-01-01

150

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

PubMed Central

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

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

2014-01-01

151

Alternative neural crest cell fates are instructively promoted by TGFbeta superfamily members.  

PubMed

How growth factors influence the fate of multipotent progenitor cells is not well understood. Most hematopoietic growth factors act selectively as survival factors, rather than instructively as lineage determination signals. In the neural crest, neuregulin instructively promotes gliogenesis, but how alternative fates are determined is unclear. We demonstrate that bone morphogenic protein 2 (BMP2) induces the basic-helix-loop-helix protein MASH1 and neurogenesis in neural crest stem cells. In vivo, MASH1+ cells are located near sites of BMP2 mRNA expression. Some smooth muscle differentiation is also observed in BMP2. A related factor, transforming growth factor beta1 (TGFbeta1), exclusively promotes smooth muscle differentiation. Like neuregulin, BMP2 and TGFbeta1 act instructively rather than selectively. The neural crest and hematopoietic systems may therefore utilize growth factors in different ways to generate cellular diversity. PMID:8616889

Shah, N M; Groves, A K; Anderson, D J

1996-05-01

152

Launching the T-Lineage Developmental Programme  

PubMed Central

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

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

2011-01-01

153

Aryl Hydrocarbon Receptor Control of Adaptive Immunity  

PubMed Central

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

2013-01-01

154

Separated at birth? The functional and molecular divergence of OLIG1 and OLIG2  

PubMed Central

Summary The basic helix-loop-helix transcription factors oligodendrocyte transcription factor 1 (OLIG1) and OLIG2 are structurally similar and, to a first approximation, coordinately expressed in the developing CNS and postnatal brain. Notwithstanding these similarities, it was apparent from early on after their discovery that OLIG1 and OLIG2 have non-overlapping developmental functions in patterning, neuron subtype specification and the formation of oligodendrocytes. Here, we summarize more recent insights into the separate functions of these transcription factors in the postnatal brain during repair processes and in neurological disease states, including multiple sclerosis and malignant glioma. We discuss how the unique biological functions of OLIG1 and OLIG2 may reflect their distinct genetic targets, co-regulator proteins and/or post-translational modifications. PMID:23165259

Meijer, Dimphna H.; Kane, Michael F.; Mehta, Shwetal; Liu, Hongye; Harrington, Emily; Taylor, Christopher M.; Stiles, Charles D.; Rowitch, David H.

2013-01-01

155

TWIST and Ovarian Cancer Stem Cells: Implications for Chemoresistance and Metastasis.  

PubMed

The transcription factor TWIST1 is a highly evolutionally conserved basic Helix-Loop-Helix (bHLH) transcription factor that functions as a master regulator of gastrulation and mesodermal development. Although TWIST1 was initially associated with embryo development, an increasing number of studies have shown TWIST1 role in the regulation of tissue homeostasis, primarily as a regulator of inflammation. More recently, TWIST1 has been found to be involved in the process of tumor metastasis through the regulation of Epithelial Mesenchymal Transition (EMT). The objective of this review is to examine the normal functions of TWIST1 and its role in tumor development, with a particular focus on ovarian cancer. We discuss the potential role of TWIST1 in the context of ovarian cancer stem cells and its influence in the process of tumor formation. PMID:25238494

Nuti, Sudhakar V; Mor, Gil; Li, Peiyao; Yin, Gang

2014-09-15

156

Determination of the DNA sequence recognized by the bHLH-zip domain of the N-Myc protein.  

PubMed Central

The DNA-binding domain of the murine N-Myc protein, comprising the basic helix-loop-helix-zipper (bHLH-zip) region was expressed as a fusion protein in E. coli. The affinity purified glutathione-S-transferase-N-Myc fusion protein (GST-N-MYC) was used to select the N-Myc specific DNA-recognition motif from a pool of random-sequence oligonucleotides. After seven rounds of binding-site selection, specifically enriched oligonucleotides were cloned and sequenced. Of 31 individual oligonucleotides whose sequences were determined, 30 contained a common DNA-motif, defining the hexameric consensus sequence CACGTG. We confirm by mutational analysis that binding of the N-Myc derived bHLH-zip domain to this motif is sequence-specific. Images PMID:1594445

Alex, R; Sozeri, O; Meyer, S; Dildrop, R

1992-01-01

157

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

SciTech Connect

Hypoxia-inducible factor 1 (HIF-1) is a basic helix-loop-helix transcription factor that mediates homeostatic responses to hypoxia. HIF-1 is a heterodimer consisting of HIF-1{alpha} which is encoded by the HIF1A gene, complexes with HIF-1{beta}, which is encoded by the ARNT gene. In this paper we report the assignment of Hif1a and HIF1A to mouse chromosome 12 and human chromosome 14, respectively. HIF1A was assigned to human chromosome 14q21-q24 by analysis of somatic cell hybrids and by fluorescence in situ hybridization. Hif1a was localized by interspecific backcross analysis within a region of mouse chromosome 12 encompassing >30 cM that demonstrates conservation of synteny with a region of human chromosome 14 extending from PAX9 at 14q12-q13 to IGHC at 14q32.33. 12 refs., 2 figs.

Semenza, G.L.; Rue, E.A.; Iyer, N.V. [Johns Hopkins Univ. School of Medicine, Baltimore, MD (United States)] [and others] [Johns Hopkins Univ. School of Medicine, Baltimore, MD (United States); and others

1996-06-15

158

Flavonoids: biosynthesis, biological functions, and biotechnological applications.  

PubMed

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

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

2012-01-01

159

Interplay between phosphorylation and SUMOylation events determines CESTA protein fate in brassinosteroid signalling.  

PubMed

Brassinosteroids (BRs) are steroid hormones that are essential for plant growth. Responses to these hormones are mediated by transcription factors of the bri1-EMS suppressor 1/brassinazole resistant 1 subfamily, and BRs activate these factors by impairing their inhibitory phosphorylation by GSK3/shaggy-like kinases. Here we show that BRs induce nuclear compartmentalization of CESTA (CES), a basic helix-loop-helix transcription factor that regulates BR responses, and reveal that this process is regulated by CES SUMOylation. We demonstrate that CES contains an extended SUMOylation motif, and that SUMOylation of this motif is antagonized by phosphorylation to control CES subnuclear localization. Moreover, we provide evidence that phosphorylation regulates CES transcriptional activity and protein turnover by the proteasome. A coordinated modification model is proposed in which, in a BR-deficient situation, CES is phosphorylated to activate target gene transcription and enable further posttranslational modification that controls CES protein stability and nuclear dynamics. PMID:25134617

Khan, Mamoona; Rozhon, Wilfried; Unterholzner, Simon Josef; Chen, Tingting; Eremina, Marina; Wurzinger, Bernhard; Bachmair, Andreas; Teige, Markus; Sieberer, Tobias; Isono, Erika; Poppenberger, Brigitte

2014-01-01

160

Id: A Target of BMP Signaling  

NSDL National Science Digital Library

Cytokines of the transforming growth factor-β (TGF-β) superfamily transduce their signals by activating receptor-regulated Smads (R-Smads). Distinct R-Smads or combinations of R-Smads are activated by TGF-β, activin, or bone morphogenetic proteins (BMPs). R-Smads activated by BMPs induce expression of Id proteins, which act as inhibitors of differentiation and stimulators of cell growth by inhibiting the function of basic helix-loop-helix transcription factors. In endothelial cells, TGF-β binds to two distinct type I receptor serine-threonine kinases, ALK-5 and ALK-1; the latter activates the same R-Smads that are activated by BMP and induces synthesis of Id (inhibitor of differentation or inhibitor of DNA binding) proteins. Growing evidence suggests that Id proteins may play crucial roles in angiogenesis, neurogenesis, and osteogenesis and act as key molecules in regulating biological responses induced by BMPs and TGF-β.

Kohei Miyazono (University of Tokyo;Department of Molecular Pathology, Graduate School of Medicine REV); Keiji Miyazawa (University of Tokyo;Department of Molecular Pathology, Graduate School of Medicine REV)

2002-09-24

161

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

PubMed

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

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

2014-09-26

162

Proprioceptor pathway development is dependent on Math1  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

163

The mouse Clock locus: sequence and comparative analysis of 204 kb from mouse chromosome 5.  

PubMed

The Clock gene encodes a basic helix-loop-helix (bHLH)-PAS transcription factor that regulates circadian rhythms in mice. We previously cloned Clock in mouse and human using a battery of behavioral and molecular techniques, including shotgun sequencing of two bacterial artificial chromosome (BAC) clones. Here we report the finished sequence of a 204-kb region from mouse chromosome 5. This region contains the complete loci for the Clock and Tpardl (pFT27) genes, as well as the 3' partial locus of the Neuromedin U gene; sequence analysis also suggests the presence of two previously unidentified genes. In addition, we provide a comparative genomic sequence analysis with the syntenic region from human chromosome 4. Finally, a new BAC transgenic line indicates that the genomic region that is sufficient for rescue of the Clock mutant phenotype is no greater than 120 kb and tightly flanks the 3' end of the Clock gene. PMID:11116088

Wilsbacher, L D; Sangoram, A M; Antoch, M P; Takahashi, J S

2000-12-01

164

TWIST and ovarian cancer stem cells: implications for chemoresistance and metastasis  

PubMed Central

The transcription factor TWIST1 is a highly evolutionally conserved basic Helix-Loop-Helix (bHLH) transcription factor that functions as a master regulator of gastrulation and mesodermal development. Although TWIST1 was initially associated with embryo development, an increasing number of studies have shown TWIST1 role in the regulation of tissue homeostasis, primarily as a regulator of inflammation. More recently, TWIST1 has been found to be involved in the process of tumor metastasis through the regulation of Epithelial Mesenchymal Transition (EMT). The objective of this review is to examine the normal functions of TWIST1 and its role in tumor development, with a particular focus on ovarian cancer. We discuss the potential role of TWIST1 in the context of ovarian cancer stem cells and its influence in the process of tumor formation. PMID:25238494

Nuti, Sudhakar V.; Mor, Gil; Li, Peiyao; Yin, Gang

2014-01-01

165

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

SciTech Connect

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

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

2007-01-26

166

Genetic regulation of vertebrate eye development.  

PubMed

Eye development is a complex and highly regulated process that consists of several overlapping stages: (i) specification then splitting of the eye field from the developing forebrain; (ii) genesis and patterning of the optic vesicle; (iii) regionalization of the optic cup into neural retina and retina pigment epithelium; and (iv) specification and differentiation of all seven retinal cell types that develop from a pool of retinal progenitor cells in a precise temporal and spatial manner: retinal ganglion cells, horizontal cells, cone photoreceptors, amacrine cells, bipolar cells, rod photoreceptors and Müller glia. Genetic regulation of the stages of eye development includes both extrinsic (such as morphogens, growth factors) and intrinsic factors (primarily transcription factors of the homeobox and basic helix-loop helix families). In the following review, we will provide an overview of the stages of eye development highlighting the role of several important transcription factors in both normal developmental processes and in inherited human eye diseases. PMID:25174583

Zagozewski, J L; Zhang, Q; Eisenstat, D D

2014-11-01

167

Basic Electricity  

NSDL National Science Digital Library

This resource, created by National Aerospace Technical Education Center (SpaceTEC), is centered on basic electricity. The presentation focuses on standards for SpaceTEC certification. Safety when using electricity is the focal point of the slides. Basic diagrams and charts illustrate the do and donâÂÂts when using electrical appliances. After the discussion of safety, the presentation shifts to the fundamental aspects of electricity. Such items as current, flow, voltage and other elements are discussed. Examples are used as representations of these basic processes. Overall, this is thorough presentation of this material. It totals nearly one-hundred twenty slides in length. Instructors could use this either as a presentation or simply to enhance existing curriculum.

2009-10-06

168

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

PubMed Central

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

Flores, Ricardo; Ruiz-Ruiz, Susana; Soler, Nuria; Sanchez-Navarro, Jesus; Fagoaga, Carmen; Lopez, Carmelo; Navarro, Luis; Moreno, Pedro; Pena, Leandro

2013-01-01

169

Basic cosmology  

E-print Network

Basic cosmology describes the universe as a Robertson-Walker model filled with black-body radiation and no barionic matter, and as observational data it uses only the value of the speed of light, the Hubble and deceleration parameters and the black-body temperature at the present epoch. It predicts the value of the next new parameter in the Hubble law.

Ll. Bel

2014-03-22

170

Dispersion Basics  

NSDL National Science Digital Library

A webcast presentation by Dr. Timothy Spangler (Director of the COMET Program and a former air quality consultant). This 25-minute lecture provides an overview of the basics of dispersion, the effects of different atmospheric conditions on dispersion, and how dispersion is commonly modeled after an accidental release of a hazardous material.

Comet

2002-11-12

171

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

PubMed Central

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

Lawrenz-Smith, S C; Thomas, C Y

1995-01-01

172

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

SciTech Connect

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

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

1996-07-01

173

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

PubMed Central

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

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

2013-01-01

174

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

PubMed Central

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

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

2012-01-01

175

Id1 expression promotes T regulatory cell differentiation by facilitating TCR costimulation.  

PubMed

T regulatory (Treg) cells play crucial roles in the regulation of cellular immunity. The development of Treg cells depends on signals from TCRs and IL-2Rs and is influenced by a variety of transcription factors. The basic helix-loop-helix proteins are known to influence TCR signaling thresholds. Whether this property impacts Treg differentiation is not understood. In this study, we interrogated the role of basic helix-loop-helix proteins in the production of Treg cells using the CD4 promoter-driven Id1 transgene. We found that Treg cells continued to accumulate as Id1 transgenic mice aged, resulting in a significant increase in Treg cell counts in the thymus as well as in the periphery compared with wild-type controls. Data from mixed bone marrow assays suggest that Id1 acts intrinsically on developing Treg cells. We made a connection between Id1 expression and CD28 costimulatory signaling because Id1 transgene expression facilitated the formation of Treg precursors in CD28(-/-) mice and the in vitro differentiation of Treg cells on thymic dendritic cells despite the blockade of costimulation by anti-CD80/CD86. Id1 expression also allowed in vitro Treg differentiation without anti-CD28 costimulation, which was at least in part due to enhanced production of IL-2. Notably, with full strength of costimulatory signals, however, Id1 expression caused modest but significant suppression of Treg induction. Finally, we demonstrate that Id1 transgenic mice were less susceptible to the induction of experimental autoimmune encephalomyelitis, thus illustrating the impact of Id1-mediated augmentation of Treg cell levels on cellular immunity. PMID:24920844

Liu, Chen; Wang, Hong-Cheng; Yu, Sen; Jin, Rong; Tang, Hui; Liu, Yuan-Feng; Ge, Qing; Sun, Xiao-Hong; Zhang, Yu

2014-07-15

176

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

PubMed Central

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

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

2009-01-01

177

GPS Basics  

NSDL National Science Digital Library

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

178

Phosphatase is responsible for run down, and probably G protein- mediated inhibition of inwardly rectifying K+ currents in guinea pig chromaffin cells  

Microsoft Academic Search

The mechanism of G protein-mediated inhibition of an inwardly rectifying K + current (IIR) in adrenal chromaffin cells was investigated using the whole-cell version of the patch clamp technique. In case of recording with use of ATP-containing patch solution, the IXR was well maintained; otherwise, it ran down within 15 min. This run down was not prevented by replacement with

M. Inoue; I. IMANAGA

1995-01-01

179

Barometer Basics  

NSDL National Science Digital Library

This experimental activity is designed to develop a basic understanding of the interrelationship between temperature and pressure and the structure of a device made to examine this relationship. Resources needed to conduct this activity include two canning jars, two large rubber balloons, a heat lamp or lamp with 150 watt bulb, and access to freezer or water and ice. The resource includes background information, teaching tips and questions to guide student discussion. This is chapter 5 of Meteorology: An Educator's Resource for Inquiry-Based Learning for Grades 5-9. The guide includes a discussion of learning science, the use of inquiry in the classroom, instructions for making simple weather instruments, and more than 20 weather investigations ranging from teacher-centered to guided and open inquiry investigations.

180

INTRODUCTION The development of the multiple cell types of a metazoan  

E-print Network

-helix-loop-helix (bHLH) transcription factor of the atonal family (Zhao and Emmons, 1995). lin-32 has been proposed, and for the proper elaboration of differentiated cell characteristics. Mutations in lin-32, a member of the atonal

Emmons, Scott

181

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

NASA Astrophysics Data System (ADS)

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

Ballard, Jake D.

182

Adult Basic Education Basic Computer Literacy Handbook.  

ERIC Educational Resources Information Center

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

Manini, Catalina M.; Cervantes, Juan

183

Mac Basic Recording Mac Basic Recording  

E-print Network

Mac Basic Recording Mac Basic Recording The Panopto (My Pitt Video) Mac Recorder allows a lot/recording. Logging In Creators are able to log in to the Mac Recorder with their credentials and record video, audio and Password" the next time the Mac Recorder is launched it will automatically login. 4. Click Create New

Benos, Panayiotis "Takis"

184

BASIC Tools: Structured Programming Techniques in BASIC.  

ERIC Educational Resources Information Center

Structured programing is an attempt to formalize the logic and structure of computer programs. Examples of structured programing techniques in BASIC are provided. Two major disadvantages of this style of programing for the personal user are noted. (JN)

Moyer, Patrick C.

1985-01-01

185

PASCAL vs BASIC  

ERIC Educational Resources Information Center

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

Mundie, David A.

1978-01-01

186

Stem Cell Basics  

MedlinePLUS

... Center Stem Cell Basics Stem Cell Basics Stem Cell Information Frequently Asked Questions What are stem cells? ... policy? More FAQs Links to related resources Stem Cell Research Center for Regenerative Medicine NIH Stem Cell ...

187

Superfund -- Basic Information  

MedlinePLUS

... Home Superfund Basic Information ? ? Basic Information What is Superfund? Superfund is the name given to the environmental ... reimburse the government for EPA-lead cleanups. How Superfund Works The Superfund cleanup process is complex. It ...

188

HIV/AIDS Basics  

MedlinePLUS

... About CDC.gov . Act Against AIDS Share Compartir HIV/AIDS Basics Before we can stop any epidemic, ... before, AIDS is still a significant health issue. HIV 101 HIV/AIDS Basic Statistics Transmission Testing Prevention ...

189

Weighted Basic Petri Nets  

Microsoft Academic Search

Basic net systems are proposed as an infinitary Petri net model which is sufficiently restrictive to allow essentially the same theory as finite nets, yet also powerful enough to describe the basic semantics of many concepts of concurrent programming languages. Weighted basic net systems are obtained if widths are assigned to the places and lengths are assigned to the transitions

Eike Best

1988-01-01

190

BASIC ELECTRICAL CONNECTION PRINCIPLES  

E-print Network

involving aluminum conductors than those encountered in copper to copper connections. CREEP (COLD FLOW is the conductor as compared to copper, since its creep rate is many times that of copper. Effect of Creep: FigureBURNDY Reference BASIC ELECTRICAL CONNECTION PRINCIPLES Basic Factors: The basic factors which

Johnson, Eric E.

191

Basic Construction Course Syllabus  

NSDL National Science Digital Library

This course syllabus provides an outline of a basic construction course. Students in this course learned "basic residential construction techniques with an emphasis on framing." The syllabus includes a basic course description and information on some class projects. This document may be downloaded in PDF file format.

Dickover, Jon

2011-12-07

192

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

SciTech Connect

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.

Seo, MiRan [Department of Biochemistry and Molecular Biology and Cancer Research Institute, Seoul National University College of Medicine, Seoul (Korea, Republic of)] [Department of Biochemistry and Molecular Biology and Cancer Research Institute, Seoul National University College of Medicine, Seoul (Korea, Republic of); Juhnn, Yong-Sung, E-mail: juhnn@snu.ac.kr [Department of Biochemistry and Molecular Biology and Cancer Research Institute, Seoul National University College of Medicine, Seoul (Korea, Republic of)] [Department of Biochemistry and Molecular Biology and Cancer Research Institute, Seoul National University College of Medicine, Seoul (Korea, Republic of)

2010-03-05

193

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

PubMed

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

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

2013-05-01

194

Protein-Mediated Adhesion of the Dissimilatory Fe(III)-Reducing Bacterium Shewanella alga BrY to Hydrous Ferric Oxide  

PubMed Central

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 HFO adhesion molecules. S. 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. PMID:10543817

Caccavo, Frank

1999-01-01

195

Visual Basic Web Directory  

NSDL National Science Digital Library

The Visual Basic Web Directory is a highly useful collection of categorized and annotated links to Websites containing information about Visual Basic. The site contains a fairly complete and easy-to-use hierarchy of resources for the Visual Basic user that range from tutorials to job listings. Beyond the resources, the site also provides summaries of recent Visual Basic news, an online bookstore linked to Amazon.com, and other interesting tidbits. In addition to the hierarchical organization of records, the site provides a simple mechanism for searching the collection. The Visual Basic Web Directory is a nicely organized Website that should prove to be a useful resource for anyone interested in Visual Basic.

196

Basic Electronics I.  

ERIC Educational Resources Information Center

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

Robertson, L. Paul

197

Fluency with Basic Addition  

ERIC Educational Resources Information Center

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

Garza-Kling, Gina

2011-01-01

198

Basic Microfluidic Lithographic  

E-print Network

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

Prentiss, Mara

199

Bracken Basic Concept Scale.  

ERIC Educational Resources Information Center

The Bracken Basic Concept Scale, for use with preschool and primary-aged children, determines a child's school readiness and knowledge of English-language verbal concepts. The instrument measures 258 basic concepts in such categories as comparisons, time, quantity, and letter identification. This paper describes test administration, scoring and…

Naglieri, Jack A.; Bardos, Achilles N.

1990-01-01

200

Basic Observables for Processes  

Microsoft Academic Search

We propose a general approach for defining behavioural preorders over process terms as the maximal pre-congruences induced by basic observables. We will consider three of these, that provide information about the initial com- munication capabilities of processes and about the possibility that processes get engaged in divergent computations. We show that the pre-congruences induced by our basic observables coincide with

Michele Boreale; Rocco De Nicola; Rosario Pugliese

1997-01-01

201

Basic Terminal Forecast Strategies  

NSDL National Science Digital Library

"Basic Terminal Forecast Strategies" is the first component of the Distance Learning Course 2, Producing Customer-Focused TAFs. Basic Terminal Forecast Strategies is comprised of two lessons that provide 1) an introduction to understanding aviation customers and their needs and 2) a technique to meet those needs by producing clear, concise, and consistent terminal aerodrome forecasts (TAFs).

Comet

2006-09-22

202

Human Body Basics  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about levels of organization in living organisms. The probe is designed to determine whether students recognize cells as the basic unit of both structure and function for carrying out basic life processes.

Eberle, Francis; Farrin, Lynn; Keeley, Page

2005-01-01

203

Solar Electric System Basics  

NSDL National Science Digital Library

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

Gordes, Joel N.

2011-10-17

204

Video Screen Capture Basics  

ERIC Educational Resources Information Center

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

Dunbar, Laura

2014-01-01

205

Body Basics Library  

MedlinePLUS

... this medical library to find out about basic human anatomy, how it all functions, and what happens when things go wrong. Blood Bones, Muscles, and Joints Brain and Nervous System Digestive System Endocrine System Eyes Female Reproductive System ...

206

Basic Electricity Materials  

NSDL National Science Digital Library

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

2010-11-24

207

Basic Electronics Tutorials  

NSDL National Science Digital Library

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

Storr, Wayne

2013-07-22

208

Reflections on Basic Science  

Microsoft Academic Search

: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

Joram Piatigorsky

2010-01-01

209

Reflections on Basic Science  

Microsoft Academic Search

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

Joram Piatigorsky

2010-01-01

210

Skywarn Spotter Convective Basics  

NSDL National Science Digital Library

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

Comet

2011-04-22

211

A membrane cytoskeleton from Dictyostelium discoideum. II. Integral proteins mediate the binding of plasma membranes to F-actin affinity beads  

PubMed Central

In novel, low-speed sedimentation assays, highly purified, sonicated Dictyostelium discoideum plasma membrane fragments bind to F-actin beads (fluorescein-labeled F-actin on antifluorescein IgG-Sephacryl S- 1000 beads). Binding was found to be (a) specific, since beads containing bound fluorescein-labeled ovalbumin or beads without bound fluorescein-labeled protein do not bind membranes, (b) saturable at approximately 0.6 microgram of membrane protein per microgram of bead- bound F-actin, (c) rapid with a t1/2 of 4-20 min, and (d) apparently of reasonable affinity since the off rate is too slow to be measured by present techniques. Using low-speed sedimentation assays, we found that sonicated plasma membrane fragments, after extraction with chaotropes, still bind F-actin beads. Heat-denatured membranes, proteolyzed membranes, and D. discoideum lipid vesicles did not bind F-actin beads. These results indicate that integral membrane proteins are responsible for the binding between sonicated membrane fragments and F-actin on beads. This finding agrees with the previous observation that integral proteins mediate interactions between D. discoideum plasma membranes and F-actin in solution (Luna, E.J., V. M. Fowler, J. Swanson, D. Branton, and D. L. Taylor, 1981, J. Cell Biol., 88:396-409). We conclude that low-speed sedimentation assays using F-actin beads are a reliable method for monitoring the associations between F-actin and membranes. Since these assays are relatively quantitative and require only micrograms of membranes and F-actin, they are a significant improvement over other existing techniques for exploring the biochemical details of F-actin-membrane interactions. Using F-actin beads as an affinity column for actin-binding proteins, we show that at least 12 integral polypeptides in D. discoideum plasma membranes bind to F-actin directly or indirectly. At least four of these polypeptides appear to span the membrane and are thus candidates for direct transmembrane links between the cytoskeleton and the cell surface. PMID:6539785

1984-01-01

212

Contrasting patterns of expression of transcription factors in pancreatic ? and ? cells  

PubMed Central

Pancreatic ? and ? cells are derived from the same progenitors but play opposing roles in the control of glucose homeostasis. Disturbances in their function are associated with diabetes mellitus. To identify many of the proteins that define their unique pathways of differentiation and functional features, we have analyzed patterns of gene expression in ?TC1.6 vs. MIN6 cell lines by using oligonucleotide microarrays. Approximately 9–10% of >11,000 transcripts examined showed significant differences between the two cell types. Of >700 known transcripts enriched in either cell type, transcription factors and their regulators (TFR) was one of the most significantly different categories. Ninety-six members of the basic zipper, basic helix–loop–helix, homeodomain, zinc finger, high mobility group, and other transcription factor families were enriched in ? cells; in contrast, homeodomain proteins accounted for 51% of a total of 45 TFRs enriched in ? cells. Our analysis thus highlights fundamental differences in expression of TFR subtypes within these functionally distinct islet cell types. Interestingly, the ? cells appear to express a large proportion of factors associated with progenitor or stem-type cells, perhaps reflecting their earlier appearance during pancreatic development. The implications of these findings for a better understanding of ? and ? cell dysfunction in diabetes mellitus are also considered. PMID:14557546

Wang, Jie; Webb, Gene; Cao, Yun; Steiner, Donald F.

2003-01-01

213

The Arabidopsis Mediator Subunit MED25 Differentially Regulates Jasmonate and Abscisic Acid Signaling through Interacting with the MYC2 and ABI5 Transcription Factors[C][W][OA  

PubMed Central

Transcriptional regulation plays a central role in plant hormone signaling. At the core of transcriptional regulation is the Mediator, an evolutionarily conserved, multisubunit complex that serves as a bridge between gene-specific transcription factors and the RNA polymerase machinery to regulate transcription. Here, we report the action mechanisms of the MEDIATOR25 (MED25) subunit of the Arabidopsis thaliana Mediator in regulating jasmonate- and abscisic acid (ABA)–triggered gene transcription. We show that during jasmonate signaling, MED25 physically associates with the basic helix-loop-helix transcription factor MYC2 in promoter regions of MYC2 target genes and exerts a positive effect on MYC2-regulated gene transcription. We also show that MED25 physically associates with the basic Leu zipper transcription factor ABA-INSENSITIVE5 (ABI5) in promoter regions of ABI5 target genes and shows a negative effect on ABI5-regulated gene transcription. Our results reveal that underlying the distinct effects of MED25 on jasmonate and ABA signaling, the interaction mechanisms of MED25 with MYC2 and ABI5 are different. These results highlight that the MED25 subunit of the Arabidopsis Mediator regulates a wide range of signaling pathways through selectively interacting with specific transcription factors. PMID:22822206

Chen, Rong; Jiang, Hongling; Li, Lin; Zhai, Qingzhe; Qi, Linlin; Zhou, Wenkun; Liu, Xiaoqiang; Li, Hongmei; Zheng, Wenguang; Sun, Jiaqiang; Li, Chuanyou

2012-01-01

214

Structure and function of the b/HLH/Z domain of USF.  

PubMed Central

The basic/helix-loop-helix/leucine zipper (b/HLH/Z) transcription factor upstream stimulatory factor (USF) and its isolated DNA binding domain undergo a random coil to alpha-helix folding transition on recognizing their cognate DNA. The USF b/HLH cocrystal structure resembles the structure of the b/HLH/Z domain of the homologous protein Max and reveals (i) that the truncated, b/HLH DNA binding domain homodimerizes, forming a parallel, left-handed four-helix bundle, and (ii) that the basic region becomes alpha-helical on binding to the major groove of the DNA sequence CACGTG. Hydrodynamic measurements show that the b/HLH/Z DNA binding domain of USF exists as a bivalent homotetramer. This tetramer forms at the USF physiological intranuclear concentration, and depends on the integrity of the leucine zipper motif. The ability to bind simultaneously to two independent sites suggests a role in DNA looping for the b/HLH/Z and Myc-related families of eukaryotic transcription factors. Images PMID:8306960

Ferre-D'Amare, A R; Pognonec, P; Roeder, R G; Burley, S K

1994-01-01

215

Olig2 overexpression accelerates the differentiation of mouse embryonic stem cells into oligodendrocyte progenitor cells in vitro.  

PubMed

Oligodendrocyte progenitor cells (OPCs) transplantation is receiving considerable attention in the field of regenerative medicine therapy for demyelinating diseases. Although embryonic stem cells (ESCs) have been successfully induced to differentiate into OPCs with cytokines cocktails in vitro, the regulatory roles of many key transcription factors in this process are not clear. Here, we introduced oligodendrocyte lineage transcription factor 2 (Olig2), a basic helix-loop-helix transcription factor, into mouse embryonic stem cells (mESCs) to investigate its effects on the differentiation of mESCs into OPCs. The results showed that Olig2 overexpression alone did not affect pluripotency of mESCs, but in the stimulation of differentiating cocktails, Olig2 accelerated mESCs to differentiate into OPCs, shortening the induction time span from normal 21 days to 11 days. Further study demonstrated the Olig2-mESCs derived OPCs were able to differentiate into C-type natriuretic peptid (CNP) and Myelin Basic Protein (MBP) positive mature oligodendrocytes (OLs) in vitro, suggesting these induced OPCs might be favorable for myelin regeneration in vivo. PMID:25200136

Yao, Ruiqin; Wang, Bei; Ren, Chuanlu; Qu, Xuebin; Luo, Mengjiao; Zhang, Qiang; Wang, Huiping; Dong, Fuxing; Wu, Xiuxiang; Yang, Lihua; Yu, Hongli

2014-09-01

216

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

PubMed Central

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

Prendergast, G C; Ziff, E B

1991-01-01

217

Basic Principles of Ultrasound  

NSDL National Science Digital Library

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

2004-01-01

218

Excel 1 - The Basics  

NSDL National Science Digital Library

Spreadsheets are used to keep track of numbers and other data in an organized fashion. It is kind of like a big calculator. In this lesson you will learn the basics of Microsoft\\'s spreadsheet program, Excel. The tutorial link below will take you through the very basics of Excel. You will start with an Overview of what Excel is and what kinds of documents it is used to create. Watch the video from the link on the right hand side of the screen. ...

Brewer, Mrs.

2006-11-25

219

Basic research championed  

NASA Astrophysics Data System (ADS)

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.

Friebele, Elaine

220

Developing Basic Electronics Aptitudes.  

ERIC Educational Resources Information Center

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…

Lakeshore Technical Coll., Cleveland, WI.

221

Focus on Basics, 1997.  

ERIC Educational Resources Information Center

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…

Focus on Basics, 1997

1997-01-01

222

Internet Training: The Basics.  

ERIC Educational Resources Information Center

This paper outlines the basic information teachers need to know to use the World Wide Web for research and communication, using Netscape 3.04. Topics covered include the following: what is the World Wide Web?; what is a browser?; accessing the Web; moving around a web document; the Uniform Resource Locator (URL); Bookmarks; saving and printing a…

Gallo, Gail; Wichowski, Chester P.

223

Bulgarian Basic Course.  

ERIC Educational Resources Information Center

This audiolingual basic course in modern Bulgarian consists of 136 lesson units in 13 volumes, supplemented by (1) a vocabulary to Volume I and II, (2) a supplementary text for Volume II, and (3) a vocabulary to Volume XII. The course, intended for the Defense Language Institute intensive language program, is designed to train native English…

1966

224

Basic Skills Assessment  

ERIC Educational Resources Information Center

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…

Yin, Alexander C.; Volkwein, J. Fredericks

2010-01-01

225

Reading for Basic Understanding.  

ERIC Educational Resources Information Center

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…

Mercer County Community Coll., Trenton, NJ.

226

Basic Pneumatics. Instructor's Guide.  

ERIC Educational Resources Information Center

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

Fessehaye, Michael

227

FULA BASIC COURSE.  

ERIC Educational Resources Information Center

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…

SWIFT, LLOYD B.; AND OTHERS

228

Assessing Basic Fact Fluency  

ERIC Educational Resources Information Center

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

Kling, Gina; Bay-Williams, Jennifer M.

2014-01-01

229

Basic Engineer Equipment Mechanic.  

ERIC Educational Resources Information Center

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

Marine Corps Inst., Washington, DC.

230

Basic Skills: Visual Arts.  

ERIC Educational Resources Information Center

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…

Kentucky State Dept. of Education, Frankfort.

231

Intellectual Patent Basics  

E-print Network

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

Heller, Barbara

232

Basic Association Rules  

Microsoft Academic Search

Previous approaches for mining association rules generate large sets of association rules. Such sets are difficult for users to understand and manage. Here, the concept of a restricted conditional probability distribution is used to explain an association rule. Based on this concept, a new type of association rules, called basic association rules, is defined. We propose the GenBR algorithm to

Guichong Li; Howard J. Hamilton

2004-01-01

233

MONITORING DROUGHT Basic Climatology  

E-print Network

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

234

Cloud Physics: The Basics  

NSDL National Science Digital Library

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

Klatt, Michael L.

2008-01-14

235

Introduction Basic dynamics  

E-print Network

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

LaCasce, Joseph H.

236

Basic Soils. Revision.  

ERIC Educational Resources Information Center

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

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

237

GPS Receiver Basics  

NSDL National Science Digital Library

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

Integrated Teaching And Learning Program

238

Basic Nuclear Physics.  

ERIC Educational Resources Information Center

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

Bureau of Naval Personnel, Washington, DC.

239

Introduction Basic thoughts  

E-print Network

is better? Why datasets without known truth? 1. Introduction IFCS task force for cluster benchmarking (Nema truth. Christian Hennig Measurement of quality in cluster analysis #12;Introduction Basic thoughts truth? Which clustering is better? (Old faithful geyser data) -2 -1 0 1 2 -2-101 mclust waiting duration

Hennig, Christian

240

Inhibitor of Differentiation 1 Promotes Endothelial Survival in a Bleomycin Model of Lung Injury in Mice  

PubMed Central

The Id family of genes encodes negative regulators of basic helix-loop-helix transcription factors and has been implicated in diverse cellular processes such as proliferation, apoptosis, differentiation, and migration. However, the specific role of Id1 in lung injury has not been investigated. Bleomycin has been widely used to generate animal models of acute lung injury and fibrogenesis. In this study we found that, on bleomycin challenge, Id1 expression was significantly up-regulated in the lungs, predominantly in endothelial cells, as revealed by double immunolabeling and quantitative flow cytometric analysis. Mice with Id1 loss-of-function (Id1?/?) displayed increased vascular permeability and endothelial apoptosis in the lungs after bleomycin-induced injury. Cultured Id1?/? lung microvascular endothelial cells also showed decreased survival when exposed to bleomycin. We detected a decrease in the level of Bcl-2, a primary anti-apoptotic protein, in Id1?/? endothelial cells, suggesting that down-regulated Bcl-2 may promote endothelial apoptosis in the lung. Therefore, we propose that Id1 plays a crucial role in promoting endothelial survival in the adult lung on injury. In addition, bleomycin-exposed Id1?/? mice showed increased lung collagen accumulation and fibrogenesis, suggesting that Id1 up-regulation in the lung may play a critical role in lung homeostasis. PMID:17717145

Zhang, Huimin; Lawson, William E.; Polosukhin, Vasiliy V.; Pozzi, Ambra; Blackwell, Timothy S.; Litingtung, Ying; Chiang, Chin

2007-01-01

241

Two R2R3-MYB genes, homologs of Petunia AN2, regulate anthocyanin biosyntheses in flower Tepals, tepal spots and leaves of asiatic hybrid lily.  

PubMed

Anthocyanins are secondary metabolites that contribute to colors of flowers, fruits and leaves. Asiatic hybrid lily (Lilium spp.) accumulates cyanidin anthocyanins in flower tepals, tepal spots and leaves of juvenile shoots. To clarify their mechanisms of regulation of anthocyanin pigmentation, two full-length cDNAs of R2R3-MYB (LhMYB6 and LhMYB12) were isolated from the anthocyanin-accumulating tepals of cultivar 'Montreux'. Analysis of the deduced amino acid sequences indicated they have homology with petunia AN2, homologous sequences of which had not been isolated in species of monocots. Yeast two-hybrid analysis showed that LhMYB6 and LhMYB12 interacted with the Lilium hybrid basic helix-loop-helix 2 (LhbHLH2) protein. Transient expression analysis indicated that co-expression of LhMYB6 and LhbHLH2 or LhMYB12 and LhbHLH2, introduced by a microprojectile, activated the transcription of anthocyanin biosynthesis genes in lily bulbscales. Spatial and temporal transcription of LhMYB6 and LhMYB12 was analyzed. The expression of LhMYB12 corresponded well with anthocyanin pigmentation in tepals, filaments and styles, and that of LhMYB6 correlated with anthocyanin spots in tepals and light-induced pigmentation in leaves. These results indicate that LhMYB6 and LhMYB12 positively regulate anthocyanin biosynthesis and determine organ- and tissue-specific accumulation of anthocyanin. PMID:20118109

Yamagishi, Masumi; Shimoyamada, Yoshihiro; Nakatsuka, Takashi; Masuda, Kiyoshi

2010-03-01

242

Heat Shock Protein 83 (Hsp83) Facilitates Methoprene-tolerant (Met) Nuclear Import to Modulate Juvenile Hormone Signaling.  

PubMed

Juvenile hormone (JH) receptors, methoprene-tolerant (Met) and Germ-cell expressed (Gce), transduce JH signals to induce Kr-h1 expression in Drosophila. Dual luciferase assay identified a 120-bp JH response region (JHRR) in the Kr-h1? promoter. Both in vitro and in vivo experiments revealed that Met and Gce transduce JH signals to induce Kr-h1 expression through the JHRR. DNA affinity purification identified chaperone protein Hsp83 as one of the proteins bound to the JHRR in the presence of JH. Interestingly, Hsp83 physically interacts with PAS-B and basic helix-loop-helix domains of Met, and JH induces Met-Hsp83 interaction. As determined by immunohistochemistry, Met is mainly distributed in the cytoplasm of fat body cells of the larval when the JH titer is low and JH induces Met nuclear import. Hsp83 was accumulated in the cytoplasm area adjunct to the nucleus in the presence of JH and Met/Gce. Loss-of-function of Hsp83 attenuated JH binding and JH-induced nuclear import of Met, resulting in a decrease in the JHRR-driven reporter activity leading to reduction of Kr-h1 expression. These data show that Hsp83 facilitates the JH-induced nuclear import of Met that induces Kr-h1 expression through the JHRR. PMID:25122763

He, Qianyu; Wen, Di; Jia, Qiangqiang; Cui, Chunlai; Wang, Jian; Palli, Subba R; Li, Sheng

2014-10-01

243

E Proteins regulate osteoclast maturation and survival  

PubMed Central

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

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

2012-01-01

244

Plant proximity perception dynamically modulates hormone levels and sensitivity in Arabidopsis.  

PubMed

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

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

2014-06-01

245

A genome-wide survey of bHLH transcription factors in the Placozoan Trichoplax adhaerens reveals the ancient repertoire of this gene family in metazoan.  

PubMed

Basic helix-loop-helix (bHLH) transcription factors play significant roles in multiple biological processes in metazoan cells. To address the evolutionary history of this gene family, comprehensive and detailed characterization in basal metazoans is essential. Here I report a genome-wide survey of bHLH genes in the Placozoan, Trichoplax adhaerens. The present survey revealed ancient origins of two orthologous families, 48-related-1/Fer1 and ASCb, which both belong to high-order Group A. Group A factors are mainly involved in neural and mesodermal differentiation. I also identified novel members of a Group E orthologous family previously thought to be unique to Homo sapiens. These were discovered in Trichoplax, Saccoglossus kowalevskii, Euperipatoides kanangrensis, and Crassostrea gigas, but apparently are not found in Drosophila melanogaster, Caenorhabditis elegans, or Nematostella vectensis. Furthermore, as reported previously, many unclassified Group A members were observed in Trichoplax. The present study provides important information to infer the ancestral state of bHLH components in the Metazoa. PMID:24631262

Gyoja, Fuki

2014-05-25

246

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

PubMed Central

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

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

2010-01-01

247

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

SciTech Connect

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

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

2007-05-25

248

BARREN STALK FASTIGIATE1 Is an AT-Hook Protein Required for the Formation of Maize Ears[W][OA  

PubMed Central

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

Gallavotti, Andrea; Malcomber, Simon; Gaines, Craig; Stanfield, Sharon; Whipple, Clinton; Kellogg, Elizabeth; Schmidt, Robert J.

2011-01-01

249

Photoexcited CRY2 interacts with CIB1 to regulate transcription and floral initiation in Arabidopsis.  

PubMed

Cryptochromes (CRY) are photolyase-like blue-light receptors that mediate light responses in plants and animals. How plant cryptochromes act in response to blue light is not well understood. We report here the identification and characterization of the Arabidopsis CIB1 (cryptochrome-interacting basic-helix-loop-helix) protein. CIB1 interacts with CRY2 (cryptochrome 2) in a blue light-specific manner in yeast and Arabidopsis cells, and it acts together with additional CIB1-related proteins to promote CRY2-dependent floral initiation. CIB1 binds to G box (CACGTG) in vitro with a higher affinity than its interaction with other E-box elements (CANNTG). However, CIB1 stimulates FT messenger RNA expression, and it interacts with chromatin DNA of the FT gene that possesses various E-box elements except G box. We propose that the blue light-dependent interaction of cryptochrome(s) with CIB1 and CIB1-related proteins represents an early photoreceptor signaling mechanism in plants. PMID:18988809

Liu, Hongtao; Yu, Xuhong; Li, Kunwu; Klejnot, John; Yang, Hongyun; Lisiero, Dominique; Lin, Chentao

2008-12-01

250

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

NASA Technical Reports Server (NTRS)

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

Schwartz, Robert J.

1997-01-01

251

The SWI/SNF KlSnf2 Subunit Controls the Glucose Signaling Pathway To Coordinate Glycolysis and Glucose Transport in Kluyveromyces lactis  

PubMed Central

In Kluyveromyces lactis, the expression of the major glucose permease gene RAG1 is controlled by extracellular glucose through a signaling cascade similar to the Saccharomyces cerevisiae Snf3/Rgt2/Rgt1 pathway. We have identified a key component of the K. lactis glucose signaling pathway by characterizing a new mutation, rag20-1, which impairs the regulation of RAG1 and hexokinase RAG5 genes by glucose. Functional complementation of the rag20-1 mutation identified the KlSNF2 gene, which encodes a protein 59% identical to S. cerevisiae Snf2, the major subunit of the SWI/SNF chromatin remodeling complex. Reverse transcription-quantitative PCR and chromatin immunoprecipitation analyses confirmed that the KlSnf2 protein binds to RAG1 and RAG5 promoters and promotes the recruitment of the basic helix-loop-helix Sck1 activator. Besides this transcriptional effect, KlSnf2 is also implicated in the glucose signaling pathway by controlling Sms1 and KlRgt1 posttranscriptional modifications. When KlSnf2 is absent, Sms1 is not degraded in the presence of glucose, leading to constitutive RAG1 gene repression by KlRgt1. Our work points out the crucial role played by KlSnf2 in the regulation of glucose transport and metabolism in K. lactis, notably, by suggesting a link between chromatin remodeling and the glucose signaling pathway. PMID:23002104

Soulard, Alexandre; Wesolowski-Louvel, Micheline; Lemaire, Marc

2012-01-01

252

Prdm13 mediates the balance of inhibitory and excitatory neurons in somatosensory circuits  

PubMed Central

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

Chang, Joshua C.; Meredith, David M.; Mayer, Paul R.; Borromeo, Mark D.; Lai, Helen C.; Ou, Yi-Hung; Johnson, Jane E.

2013-01-01

253

Conditional deletion of neurogenin-3 using Nkx2.1iCre results in a mouse model for the central control of feeding, activity and obesity  

PubMed Central

SUMMARY The ventral hypothalamus acts to integrate visceral and systemic information to control energy balance. The basic helix-loop-helix transcription factor neurogenin-3 (Ngn3) is required for pancreatic ?-cell development and has been implicated in neuronal development in the hypothalamus. Here, we demonstrate that early embryonic hypothalamic inactivation of Ngn3 (also known as Neurog3) in mice results in rapid post-weaning obesity that is associated with hyperphagia and reduced energy expenditure. This obesity is caused by loss of expression of Pomc in Pomc- and Cart-expressing (Pomc/Cart) neurons in the arcuate nucleus, indicating an incomplete specification of anorexigenic first order neurons. Furthermore, following the onset of obesity, both the arcuate and ventromedial hypothalamic nuclei become insensitive to peripheral leptin treatment. This conditional mouse mutant therefore represents a novel model system for obesity that is associated with hyperphagia and underactivity, and sheds new light upon the roles of Ngn3 in the specification of hypothalamic neurons controlling energy balance. PMID:23649822

Anthwal, Neal; Pelling, Michelle; Claxton, Suzanne; Mellitzer, Georg; Collin, Caitlin; Kessaris, Nicoletta; Richardson, William D.; Gradwohl, Gerard; Ang, Siew-Lan

2013-01-01

254

Generation and characterization of ScxCre transgenic mice.  

PubMed

Scleraxis (Scx) is a basic helix-loop-helix transcription factor that is a marker for the tendon/ligament cell lineage. The ?11 kb genomic region from the mouse Scx gene locus faithfully recapitulates the endogenous Scx expression pattern in ScxGFP transgenic (Tg) mice. We have established two Tg mouse lines expressing Cre-recombinase (Cre) using this regulatory region (ScxCre-L and ScxCre-H). The specificity and efficiency of Cre recombination in these Tg lines are evaluated by crossing with Rosa-CAG-LSL-tdTomato (Ai14) or ROSA26R (R26R) reporter mice. The recombination in ScxCre-H;Ai14 mice is efficiently achieved in the endogenous Scx expression domains including the branchial arches, the syndetome, and the lateral plate mesoderm. Further analysis of ScxCre-H;Ai14;ScxGFP embryos reveal that expression of the ScxGFP transgene largely overlaps with Cre activity detected by tdTomato at embryonic day 12.5 (E12.5). In ScxCre-L;R26R or ScxCre-H;R26R neonates, Cre activity is detected in tendons, ligaments, intervertebral discs, joints, and cartilage around the chondro-tendinous/ligamentous junction, the prospective enthesis. The present results suggest that ScxCre Tg lines are useful for targeting the gene specifically in the Scx-expressing domains. PMID:23349075

Sugimoto, Yuki; Takimoto, Aki; Hiraki, Yuji; Shukunami, Chisa

2013-04-01

255

USP17- and SCF?TrCP-Regulated Degradation of DEC1 Controls the DNA Damage Response.  

PubMed

In response to genotoxic stress, DNA damage checkpoints maintain the integrity of the genome by delaying cell cycle progression to allow for DNA repair. Here we show that the degradation of the basic helix-loop-helix (bHLH) transcription factor DEC1, a critical regulator of cell fate and circadian rhythms, controls the DNA damage response. During unperturbed cell cycles, DEC1 is a highly unstable protein that is targeted for proteasome-dependent degradation by the SCF(?TrCP) ubiquitin ligase in cooperation with CK1. Upon DNA damage, DEC1 is rapidly induced in an ATM/ATR-dependent manner. DEC1 induction results from protein stabilization via a mechanism that requires the USP17 ubiquitin protease. USP17 binds and deubiquitylates DEC1, markedly extending its half-life. Subsequently, during checkpoint recovery, DEC1 proteolysis is reestablished through ?TrCP-dependent ubiquitylation. Expression of a degradation-resistant DEC1 mutant prevents checkpoint recovery by inhibiting the downregulation of p53. These results indicate that the regulated degradation of DEC1 is a key factor controlling the DNA damage response. PMID:25202122

Kim, Jihoon; D'Annibale, Sara; Magliozzi, Roberto; Low, Teck Yew; Jansen, Petra; Shaltiel, Indra A; Mohammed, Shabaz; Heck, Albert J R; Medema, Rene H; Guardavaccaro, Daniele

2014-11-15

256

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

PubMed Central

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

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

2012-01-01

257

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

PubMed Central

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

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

2014-01-01

258

The Purple Cauliflower Arises from Activation of a MYB Transcription Factor1[W][OA  

PubMed Central

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

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

2010-01-01

259

Identification of Specific DNA Binding Residues in the TCP Family of Transcription Factors in Arabidopsis[W  

PubMed Central

The TCP transcription factors control multiple developmental traits in diverse plant species. Members of this family share an ?60-residue-long TCP domain that binds to DNA. The TCP domain is predicted to form a basic helix-loop-helix (bHLH) structure but shares little sequence similarity with canonical bHLH domain. This classifies the TCP domain as a novel class of DNA binding domain specific to the plant kingdom. Little is known about how the TCP domain interacts with its target DNA. We report biochemical characterization and DNA binding properties of a TCP member in Arabidopsis thaliana, TCP4. We have shown that the 58-residue domain of TCP4 is essential and sufficient for binding to DNA and possesses DNA binding parameters comparable to canonical bHLH proteins. Using a yeast-based random mutagenesis screen and site-directed mutants, we identified the residues important for DNA binding and dimer formation. Mutants defective in binding and dimerization failed to rescue the phenotype of an Arabidopsis line lacking the endogenous TCP4 activity. By combining structure prediction, functional characterization of the mutants, and molecular modeling, we suggest a possible DNA binding mechanism for this class of transcription factors. PMID:20363772

Aggarwal, Pooja; Das Gupta, Mainak; Joseph, Agnel Praveen; Chatterjee, Nirmalya; Srinivasan, N.; Nath, Utpal

2010-01-01

260

DNA-binding activity of the transcription factor upstream stimulatory factor 1 (USF-1) is regulated by cyclin-dependent phosphorylation.  

PubMed Central

The ubiquitous transcription factor upstream stimulatory factor (USF) 1 is a member of the bzHLH (leucine zipper-basic-helix-loop-helix) family, which is structurally related to the Myc family of proteins. It plays a role in the regulation of many genes, including the cyclin B1 gene, which is active during the G2/M and M phases of the cell cycle and may also play a role in the regulation of cellular proliferation. We show that the affinity of recombinant USF-1 for DNA is greatly increased by treatment with active cyclin A2-p34(cdc2) or cyclin B1-p34(cdc2) complexes and that its interaction with DNA is dependent on p34(cdc2)-mediated phosphorylation. We have localized the phosphorylation site(s) to a region that lies outside the minimal DNA-binding domain but overlaps with the previously identified USF-specific region. Deletion studies of USF-1 suggest that amino acids 143-197 regulate DNA-binding activity in a phosphorylation-dependent manner. PMID:10548544

Cheung, E; Mayr, P; Coda-Zabetta, F; Woodman, P G; Boam, D S

1999-01-01

261

An upstream open reading frame represses expression of Lc, a member of the R/B family of maize transcriptional activators  

SciTech Connect

The R/B genes of maize encode a family of basic helix-loop-helix proteins that determine where and when the anthocyanin-pigment pathway will be expressed in the plant. Previous studies showed that allelic diversity among family members reflects differences in gene expression, specifically in transcription initiation. The authors present evidence that the R gene Lc is under translational control. They demonstrate that the 235-nt transcript leader of Lc represses expression 25- to 30-fold in an in vivo assay. Repression is mediated by the presence in cis of a 38-codon upstream open reading frame. Furthermore, the coding capacity of the upstream open reading frame influences the magnitude of repression. It is proposed that translational control does not contribute to tissue specificity but prevents overexpression of the Lc protein. The diversity of promoter and 5' untranslated leader sequences among the R/B genes provides an opportunity to study the coevolution of transcriptional and translational mechanisms of gene regulation. 36 refs., 5 figs.

Damiani, R.D. Jr.; Wessler, S.R. (Univ. of Georgia, Athens, GA (United States))

1993-09-01

262

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

PubMed

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

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

2011-01-01

263

Insulin induces transcription of target genes through the hypoxia-inducible factor HIF-1alpha/ARNT.  

PubMed Central

Hypoxic stress induces the expression of genes associated with increased energy flux, including the glucose transporters Glut1 and Glut3, several glycolytic enzymes, nitric oxide synthase, tyrosine hydroxylase, erythropoietin and vascular endothelial growth factor (VEGF). Induction of these genes is mediated by a common basic helix-loop-helix-PAS transcription complex, the hypoxia-inducible factor-1alpha (HIF-1alpha)/aryl hydrocarbon nuclear translocator (ARNT). Insulin also induces some of these genes; however, the underlying mechanism is unestablished. We report here that insulin shares with hypoxia the ability to induce the HIF-1alpha/ARNT transcription complex in various cell types. This induction was demonstrated by electrophoretic mobility shift of the hypoxia response element (HRE), and abolished by specific antisera to HIF-1alpha and ARNT, and by transcription activation of HRE reporter vectors. Furthermore, basal and insulin-induced expression of Glut1, Glut3, aldolase A, phosphoglycerate kinase and VEGF was reduced in cells having a defective ARNT. Similarly, the insulin-induced activation of HRE reporter vectors and VEGF was impaired in these cells and was rescued by re-introduction of ARNT. Finally, insulin-like growth factor-I (IGF-I) also induced the HIF-1alpha/ARNT transcription complex. These observations establish a novel signal transduction pathway of insulin and IGF-I and broaden considerably the scope of activity of HIF-1alpha/ARNT. PMID:9724644

Zelzer, E; Levy, Y; Kahana, C; Shilo, B Z; Rubinstein, M; Cohen, B

1998-01-01

264

The Notch Pathway Inhibits TGF? Signaling in Breast Cancer through HEYL-Mediated Crosstalk.  

PubMed

Acquired resistance to TGF? is a key step in the early stages of tumorigenesis. Mutations in TGF? 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 TGF? activity by binding to TGF?-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? signaling by Notch acting through HEYL may promote initiation of breast cancer. Cancer Res; 74(22); 6509-18. ©2014 AACR. PMID:25217524

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

265

Independently specified Atoh1 domains define novel developmental compartments in rhombomere 1.  

PubMed

The rhombic lip gives rise to neuronal populations that contribute to cerebellar, proprioceptive and interoceptive networks. Cell production depends on the expression of the basic helix-loop-helix (bHLH) transcription factor Atoh1. In rhombomere 1, Atoh1-positive cells give rise to both cerebellar neurons and extra-cerebellar nuclei in ventral hindbrain. The origin of this cellular diversity has previously been attributed to temporal signals rather than spatial patterning. Here, we show that in both chick and mouse the cerebellar Atoh1 precursor pool is partitioned into initially cryptic spatial domains that reflect the activity of two different organisers: an isthmic Atoh1 domain, which gives rise to isthmic nuclei, and the rhombic lip, which generates deep cerebellar nuclei and granule cells. We use a combination of in vitro explant culture, genetic fate mapping and gene overexpression and knockdown to explore the role of isthmic signalling in patterning these domains. We show that an FGF-dependent isthmic Atoh1 domain is the origin of distinct populations of Lhx9-positive neurons in the extra-cerebellar isthmic nuclei. In the cerebellum, ectopic FGF induces proliferation while blockade reduces the length of the cerebellar rhombic lip. FGF signalling is not required for the specification of cerebellar cell types from the rhombic lip and its upregulation inhibits their production. This suggests that although the isthmus regulates the size of the cerebellar anlage, the downregulation of isthmic FGF signals is required for induction of rhombic lip-derived cerebellar neurons. PMID:24381197

Green, Mary J; Myat, Anna M; Emmenegger, Brian A; Wechsler-Reya, Robert J; Wilson, Leigh J; Wingate, Richard J T

2014-01-01

266

A bHLH-Type Transcription Factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1, Acts as a Repressor to Negatively Regulate Jasmonate Signaling in Arabidopsis[C][W  

PubMed Central

Jasmonates (JAs) are plant hormones that regulate the balance between plant growth and responses to biotic and abiotic stresses. Although recent studies have uncovered the mechanisms for JA-induced responses in Arabidopsis thaliana, the mechanisms by which plants attenuate the JA-induced responses remain elusive. Here, we report that a basic helix-loop-helix–type transcription factor, ABA-INDUCIBLE BHLH-TYPE TRANSCRIPTION FACTOR/JA-ASSOCIATED MYC2-LIKE1 (JAM1), acts as a transcriptional repressor and negatively regulates JA signaling. Gain-of-function transgenic plants expressing the chimeric repressor for JAM1 exhibited substantial reduction of JA responses, including JA-induced inhibition of root growth, accumulation of anthocyanin, and male fertility. These plants were also compromised in resistance to attack by the insect herbivore Spodoptera exigua. Conversely, jam1 loss-of-function mutants showed enhanced JA responsiveness, including increased resistance to insect attack. JAM1 and MYC2 competitively bind to the target sequence of MYC2, which likely provides the mechanism for negative regulation of JA signaling and suppression of MYC2 functions by JAM1. These results indicate that JAM1 negatively regulates JA signaling, thereby playing a pivotal role in fine-tuning of JA-mediated stress responses and plant growth. PMID:23673982

Nakata, Masaru; Mitsuda, Nobutaka; Herde, Marco; Koo, Abraham J.K.; Moreno, Javier E.; Suzuki, Kaoru; Howe, Gregg A.; Ohme-Takagi, Masaru

2013-01-01

267

Specification of neurotransmitter receptor identity in developing retina: the chick ATH5 promoter integrates the positive and negative effects of several bHLH proteins.  

PubMed

Genetic studies in Drosophila and in vertebrates have implicated basic helix-loop-helix (bHLH) transcription factors in neural determination and differentiation. In this report, we analyze the role that several bHLH proteins play in the transcriptional control of differentiation in chick retina. Our experimental system exploits the properties of the promoter for the beta 3 subunit of the neuronal acetylcholine receptors, important components of various phenotypes in the CNS of vertebrates. The beta 3 subunit contributes to define ganglion cell identity in retina and its promoter, whose activation is an early marker of ganglion cell differentiation, is under the specific control of the chick atonal homolog ATH5. Functional analysis of the ATH5 promoter indicates that interactions between ATH5 and several other bHLH transcription factors underlie the patterning of the early retinal neuroepithelium and form a regulatory cascade leading to transcription of the gene for beta 3. ATH5 appears to coordinate the transcriptional pathways that control pan-neuronal properties with those that regulate the subtype-specific features of retinal neurons. PMID:11124117

Matter-Sadzinski, L; Matter, J M; Ong, M T; Hernandez, J; Ballivet, M

2001-01-01

268

Translocation breakpoint maps 5 kb 3 ? from TWIST in a patient affected with Saethre–Chotzen syndrome  

E-print Network

Saethre–Chotzen syndrome, a common autosomal dominant craniosynostosis in humans, is characterized by brachydactyly, soft tissue syndactyly and facial dysmorphism including ptosis, facial asymmetry, and prominent ear crura. Previously, we identified a yeast artificial chromosome that encompassed the breakpoint of an apparently balanced t(6;7) (q16.2;p15.3) translocation associated with a mild form of Saethre–Chotzen syndrome. We now describe, at the DNA sequence level, the region on chromosome 7 affected by this translocation event. The rearrangement occurred ?5 kb 3 ? of the human TWIST locus and deleted 518 bp of chromosome 7. The TWIST gene codes for a transcription factor containing a basic helix–loop–helix (b-HLH) motif and has recently been described as a candidate gene for Saethre–Chotzen syndrome, based on the detection of mutations within the coding region. Potential exon sequences flanking the chromosome 7 translocation breakpoint did not hit known genes in database searches. The chromosome rearrangement downstream of TWIST is compatible with the notion that this is a Saethre–Chotzen syndrome gene and implies loss of function of one allele by a positional effect as a possible mechanism of mutation to evoke the syndrome.

unknown authors

1997-01-01

269

Autoregulation of Th1-mediated inflammation by twist1  

PubMed Central

The basic helix-loop-helix transcriptional repressor twist1, as an antagonist of nuclear factor ?B (NF-?B)–dependent cytokine expression, is involved in the regulation of inflammation-induced immunopathology. We show that twist1 is expressed by activated T helper (Th) 1 effector memory (EM) cells. Induction of twist1 in Th cells depended on NF-?B, nuclear factor of activated T cells (NFAT), and interleukin (IL)-12 signaling via signal transducer and activator of transcription (STAT) 4. Expression of twist1 was transient after T cell receptor engagement, and increased upon repeated stimulation of Th1 cells. Imprinting for enhanced twist1 expression was characteristic of repeatedly restimulated EM Th cells, and thus of the pathogenic memory Th cells characteristic of chronic inflammation. Th lymphocytes from the inflamed joint or gut tissue of patients with rheumatic diseases, Crohn's disease or ulcerative colitis expressed high levels of twist1. Expression of twist1 in Th1 lymphocytes limited the expression of the cytokines interferon-?, IL-2, and tumor necrosis factor-?, and ameliorated Th1-mediated immunopathology in delayed-type hypersensitivity and antigen-induced arthritis. PMID:18663125

Niesner, Uwe; Albrecht, Inka; Janke, Marko; Doebis, Cornelia; Loddenkemper, Christoph; Lexberg, Maria H.; Eulenburg, Katharina; Kreher, Stephan; Koeck, Juliana; Baumgrass, Ria; Bonhagen, Kerstin; Kamradt, Thomas; Enghard, Philipp; Humrich, Jens Y.; Rutz, Sascha; Schulze-Topphoff, Ulf; Aktas, Orhan; Bartfeld, Sina; Radbruch, Helena; Hegazy, Ahmed N.; Löhning, Max; Baumgart, Daniel C.; Duchmann, Rainer; Rudwaleit, Martin; Häupl, Thomas; Gitelman, Inna; Krenn, Veit; Gruen, Joachim; Sieper, Jochen; Zeitz, Martin; Wiedenmann, Bertram; Zipp, Frauke; Hamann, Alf; Janitz, Michal; Scheffold, Alexander; Burmester, Gerd R.; Chang, Hyun D.; Radbruch, Andreas

2008-01-01

270

Control of precerebellar neuron development by Olig3 bHLH transcription factor.  

PubMed

The rhombic lip (RL) is the neuroepithelium immediately adjacent to the roof plate of the fourth ventricle, and it gives rise to various brainstem and cerebellar cell types. Our study shows that the bHLH (basic helix-loop-helix) transcription factor Olig3 is expressed in the progenitors of RL, and ablation of Olig3 significantly affects the development of RL. In Olig3-/- caudal RL, the expression level of Math1 in the dorsal interneuron 1 (dI1) domain is reduced, and the formation of four mossy-fiber nuclei is compromised; dI2-dI3 neurons are misspecified to dI4 interneurons, and the climbing-fiber neurons (inferior olive nucleus) are completely lost. In addition, the formation of brainstem (nor)adrenergic centers and first-order relay visceral sensory neurons is also dependent on Olig3. Therefore, Olig3 plays an important role in the fate specification and differentiation of caudal RL-derived neurons. PMID:18829970

Liu, Zijing; Li, Hong; Hu, Xuemei; Yu, Ling; Liu, Hongbin; Han, Ruifa; Colella, Rita; Mower, George D; Chen, Yiping; Qiu, Mengsheng

2008-10-01

271

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

PubMed Central

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

Li, Yan

2012-01-01

272

Correct Timing of Proliferation and Differentiation is Necessary for Normal Inner Ear Development and Auditory Hair Cell Viability  

PubMed Central

Background Hearing restoration through hair cell regeneration will require revealing the dynamic interactions between proliferation and differentiation during development to avoid the limited viability of regenerated hair cells. Pax2-Cre N-Myc conditional knockout (CKO) mice highlighted the need of N-Myc for proper neurosensory development and possible redundancy with L-Myc. The late-onset hair cell death in the absence of early N-Myc expression could be due to mis-regulation of genes necessary for neurosensory formation and maintenance, such as Neurod1, Atoh1, Pou4f3, and Barhl1. Results Pax2-Cre N-Myc L-Myc double CKO mice show that proliferation and differentiation are linked together through Myc and in the absence of both Mycs, altered proliferation and differentiation results in morphologically abnormal ears. In particular, the organ of Corti apex is re-patterned into a vestibular-like organization and the base is truncated and fused with the saccule. Conclusions These data indicate that therapeutic approaches to restore hair cells must take into account a dynamic interaction of proliferation and differentiation regulation of basic Helix-Loop-Helix transcription factors in attempts to stably replace lost cochlear hair cells. In addition, our data indicate that Myc is an integral component of the evolutionary transformation process that resulted in the organ of Corti development. PMID:23193000

Kopecky, Benjamin J.; Jahan, Israt; Fritzsch, Bernd

2013-01-01

273

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

PubMed Central

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

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

2014-01-01

274

Id2 controls chondrogenesis acting downstream of BMP signaling during maxillary morphogenesis.  

PubMed

Maxillofacial dysmorphogenesis is found in 5% of the population. To begin to understand the mechanisms required for maxillofacial morphogenesis, we employed the inhibitors of the differentiation 2 (Id2) knock-out mouse model, in which Id proteins, members of the regulator of basic helix-loop-helix (bHLH) transcription factors, modulate cell proliferation, apoptosis, and differentiation. We now report that spatially-restricted growth defects are localized at the skull base of Id2 KO mice. Curiously, at birth, neither the mutant Id2 KO nor wild-type (WT) mice differed, based upon cephalometric and histological analyses of cranial base synchondroses. In postnatal week 2, a narrower hypertrophic zone and an inhibited proliferative zone in presphenoid synchondrosis (PSS) and spheno-occipital synchondrosis (SOS) with maxillary hypoplasia were identified in the Id2 mutant mice. Complementary studies revealed that exogenous bone morphogenetic proteins (BMPs) enhanced cartilage growth, matrix deposition, and chondrocyte proliferation in the WT but not in the mutant model. Id2-deficient chondrocytes expressed more Smad7 transcripts. Based on our results, we assert that Id2 plays an essential role, acting downstream of BMP signaling, to regulate cartilage formation at the postnatal stage by enhancing BMP signals through inhibiting Smad7 expression. As a consequence, abnormal endochondral ossification was observed in cranial base synchondroses during the postnatal growth period, resulting in the clinical phenotype of maxillofacial dysmorphogenesis. PMID:21985998

Sakata-Goto, Tomoko; Takahashi, Katsu; Kiso, Honoka; Huang, Boyen; Tsukamoto, Hiroko; Takemoto, Mitsuru; Hayashi, Tatsunari; Sugai, Manabu; Nakamura, Takashi; Yokota, Yoshifumi; Shimizu, Akira; Slavkin, Harold; Bessho, Kazuhisa

2012-01-01

275

Aberrant expression of the transcription factor Twist in adult T-cell leukemia.  

PubMed

Adult T-cell leukemia (ATL) is a T-cell malignancy etiologically associated with human T-cell leukemia virus type 1 (HTLV-1). Twist, a highly conserved basic helix-loop-helix transcription factor, is a newly identified oncogene. However, there are no reports on Twist expression in ATL. To define the role of Twist in leukemogenesis of ATL, we examined its expression in T-cell lines and PBMC. HTLV-1-infected T-cell lines and ATL cells expressed high levels of Twist compared with uninfected T-cell lines and normal PBMC. Immunohistochemistry showed immunostaining for Twist in ATL cells in ATL lymph nodes and skin lesions. Infection of normal PBMC with HTLV-1 induced Twist expression. Induction of the viral protein Tax in a human T-cell line led to upregulation of Twist. Tax-induced Twist expression involved the NF-kappaB and CREB signaling pathways. Twist augmented Tax-mediated HTLV-1 LTR and NF-kappaB activation. Short interfering RNA against Twist inhibited cell growth of HTLV-1-infected T-cell lines and downregulation of Twist expression in an HTLV-1-infected T-cell line inhibited the expression of Akt1, interleukin-2 receptor alpha chain, and Tax as well as the known target genes of Twist, YB-1 and Akt2. In conclusion, the results suggest that Tax-induced induction of Twist contributes to leukemogenesis of ATL. PMID:20071663

Tanji, Hiroe; Ishikawa, Chie; Sawada, Shigeki; Nakachi, Sawako; Takamatsu, Reika; Matsuda, Takehiro; Okudaira, Taeko; Uchihara, Jun-Nosuke; Ohshiro, Kazuiku; Tanaka, Yuetsu; Senba, Masachika; Uezato, Hiroshi; Ohshima, Koichi; Duc Dodon, Madeleine; Wu, Kou-Juey; Mori, Naoki

2010-01-13

276

SWI/SNF chromatin remodeling ATPase Brm regulates the differentiation of early retinal stem cells/progenitors by influencing Brn3b expression and Notch signaling.  

PubMed

Based on a variety of approaches, evidence suggests that different cell types in the vertebrate retina are generated by multipotential progenitors in response to interactions between cell intrinsic and cell extrinsic factors. The identity of some of the cellular determinants that mediate such interactions has emerged, shedding light on mechanisms underlying cell differentiation. For example, we know now that Notch signaling mediates the influence of the microenvironment on states of commitment of the progenitors by activating transcriptional repressors. Cell intrinsic factors such as the proneural basic helix-loop-helix and homeodomain transcription factors regulate a network of genes necessary for cell differentiation and maturation. What is missing from this picture is the role of developmental chromatin remodeling in coordinating the expression of disparate classes of genes for the differentiation of retinal progenitors. Here we describe the role of Brm, an ATPase in the SWI/SNF chromatin remodeling complex, in the differentiation of retinal progenitors into retinal ganglion cells. Using the perturbation of expression and function analyses, we demonstrate that Brm promotes retinal ganglion cell differentiation by facilitating the expression and function of a key regulator of retinal ganglion cells, Brn3b, and the inhibition of Notch signaling. In addition, we demonstrate that Brm promotes cell cycle exit during retinal ganglion cell differentiation. Together, our results suggest that Brm represents one of the nexus where diverse information of cell differentiation is integrated during cell differentiation. PMID:17855369

Das, Ani V; James, Jackson; Bhattacharya, Sumitra; Imbalzano, Anthony N; Antony, Marie Lue; Hegde, Ganapati; Zhao, Xing; Mallya, Kavita; Ahmad, Faraz; Knudsen, Eric; Ahmad, Iqbal

2007-11-30

277

Brassinosteroid Signaling Pathway  

NSDL National Science Digital Library

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

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

2006-12-05

278

Genomic cloning and chromosomal localization of HRY, the human homolog to the Drosophila segmentation gene, hairy  

SciTech Connect

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.

Feder, J.N.; Jan, L.Y.; Jan, Y.N.; Li, L. (Univ. of California, San Francisco, CA (United States))

1994-03-01

279

Oligodendrocyte lineage genes (OLIG) as molecular markers for human glial brain tumors  

PubMed Central

The most common primary tumors of the human brain are thought to be of glial cell origin. However, glial cell neoplasms cannot be fully classified by cellular morphology or with conventional markers for astrocytes, oligodendrocytes, or their progenitors. Recent insights into central nervous system tumorigenesis suggest that novel molecular markers might be found among factors that have roles in glial development. Oligodendrocyte lineage genes (Olig1/2) encode basic helix–loop–helix transcription factors. In the rodent central nervous system, they are expressed exclusively in oligodendrocytes and oligodendrocyte progenitors, and Olig1 can promote formation of an chondroitin sulfate proteoglycon-positive glial progenitor. Here we show that human OLIG genes are expressed strongly in oligodendroglioma, contrasting absent or low expression in astrocytoma. Our data provide evidence that neoplastic cells of oligodendroglioma resemble oligodendrocytes or their progenitor cells and may derive from cells of this lineage. They further suggest the diagnostic potential of OLIG markers to augment identification of oligodendroglial tumors. PMID:11526205

Lu, Q. Richard; Park, John K.; Noll, Elizabeth; Chan, Jennifer A.; Alberta, John; Yuk, Dongin; Alzamora, M. Garcia; Louis, David N.; Stiles, Charles D.; Rowitch, David H.; Black, Peter M.

2001-01-01

280

MondoA deficiency enhances sprint performance in mice.  

PubMed

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

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

2014-11-15

281

Achaete-Scute Homologue-1 Tapers Neuroendocrine Cell Differentiation in Lungs after Exposure to Naphthalene  

PubMed Central

The basic helix-loop-helix transcription factor achaete-scute homologue-1 (ASH1) plays a critical role in regulating the neuroendocrine (NE) phenotype in normal and neoplastic lung. Transgenic (TG) mice that constitutively express human ASH1 (hASH1) under control of the Clara cell 10-kDa protein (CC10) promoter in non-NE airway lining cells display progressive epithelial hyperplasia and bronchiolar metaplasia or bronchiolization of the alveoli (BOA). However, little is known about the involvement of hASH1 in regeneration of the conducting airway. In this study, we investigated the impact of hASH1 on airway cell injury and repair in the TG mice following an intraperitoneal injection of naphthalene, which specifically ablates bronchiolar Clara cells and induces pulmonary NE cell hyperplasia. We discovered an overall attenuation of NE maturation coupled with increased proliferation in TG mice during post-naphthalene repair. In addition, BOA lesions revealed enhanced epithelial cell proliferation while preserving Clara cell markers CC10 and the principal naphthalene-metabolizing enzyme cytochrome P4502F2. These data suggest that ASH1 may play an important role in maintaining a progenitor phenotype that promotes renewal of both NE and epithelial cells. Moreover, ASH1 may propagate a stem cell microenvironment in BOA where epithelium becomes resistant to naphthalene toxicity. PMID:20554700

Jensen-Taubman, Sandra; Wang, Xiao-Yang; Linnoila, R. Ilona

2010-01-01

282

Phosphatidic acid and phosphoinositides facilitate liposome association of Yas3p and potentiate derepression of ARE1 (alkane-responsive element one)-mediated transcription control.  

PubMed

In the n-alkane assimilating yeast Yarrowia lipolytica, the expression of ALK1, encoding a cytochrome P450 that catalyzes terminal mono-oxygenation of n-alkanes, is induced by n-alkanes. The transcription of ALK1 is regulated by a heterocomplex that comprises the basic helix-loop-helix transcription activators, Yas1p and Yas2p, and binds to alkane-responsive element 1 (ARE1) in the ALK1 promoter. An Opi1 family transcription repressor, Yas3p, represses transcription by binding to Yas2p. Yas3p localizes in the nucleus when Y. lipolytica is grown on glucose but localizes to the endoplasmic reticulum (ER) upon the addition of n-alkanes. In this study, we showed that recombinant Yas3p binds to the acidic phospholipids, phosphatidic acid (PA) and phosphoinositides (PIPs), in vitro. The ARE1-mediated transcription was enhanced in vivo in mutants defective in an ortholog of the Saccharomyces cerevisiae gene PAH1, encoding PA phosphatase, and in an ortholog of SAC1, encoding PIP phosphatase in the ER. Truncation mutation analyses for Yas3p revealed two regions that bound to PA and PIPs. These results suggest that the interaction with acidic phospholipids is important for the n-alkane-induced association of Yas3p with the ER membrane. PMID:24120453

Kobayashi, Satoshi; Hirakawa, Kiyoshi; Horiuchi, Hiroyuki; Fukuda, Ryouichi; Ohta, Akinori

2013-12-01

283

The aryl hydrocarbon receptor: Regulation of hematopoiesis and involvement in the progression of blood diseases  

PubMed Central

The aryl hydrocarbon receptor (AhR) is a basic helix-loop-helix protein that belongs to the superfamily of environment-sensing PAS (Per-ARNT-Sim) proteins. A large number of ligands have been described to bind AhR and promote its nuclear translocation. In the nucleus, the AhR and its dimerization partner the AhR nuclear translocase (ARNT), also known as HIF1?, form a DNA-binding complex that acts as a transcriptional regulator. Animal and human data suggest that, beyond its mediating responses to xenobiotic and/or unknown endogenous ligands, the AhR has a role, although as yet undefined, in the regulation of cell cycle and inflammation. The AhR also appears to regulate the hematopoietic and immune systems during development and adult life in a cell-specific manner. While accidental exposure to xenobiotic AhR ligands has been associated with leukemia in humans, the specific mechanisms of AhR involvement are still not completely understood. However, recent data are consistent with a functional role of the AhR in the maintenance of hematopoietic stem and/or progenitor cells (HSCs/HPCs). Studies highlighting AhR-regulation of HSCs/HPCs provide a rational framework to understand their biology, a role of the AhR in hematopoietic diseases, and a means to develop interventions for these diseases. PMID:20171126

Casado, Fanny L.; Singh, Kameshwar P.; Gasiewicz, Thomas A.

2010-01-01

284

Arabidopsis noncoding RNA mediates control of photomorphogenesis by red light.  

PubMed

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

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

2014-07-15

285

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

PubMed Central

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

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

286

A bHLH transcription factor, DvIVS, is involved in regulation of anthocyanin synthesis in dahlia (Dahlia variabilis)  

PubMed Central

Dahlias (Dahlia variabilis) exhibit a wide range of flower colours because of accumulation of anthocyanin and other flavonoids in their ray florets. Two lateral mutants were used that spontaneously occurred in ‘Michael J’ (MJW) which has yellow ray florets with orange variegation. MJOr, a bud mutant producing completely orange ray florets, accumulates anthocyanins, flavones, and butein, and MJY, another mutant producing completely yellow ray florets, accumulates flavones and butein. Reverse transcription–PCR analysis showed that expression of chalcone synthase 1 (DvCHS1), flavanone 3-hydroxylase (DvF3H), dihydroflavonol 4-reductase (DvDFR), anthocyanidin synthase (DvANS), and DvIVS encoding a basic helix–loop–helix transcription factor were suppressed, whereas that of chalcone isomerase (DvCHI) and DvCHS2, another CHS with 69% nucleotide identity with DvCHS1, was not suppressed in the yellow ray florets of MJY. A 5.4?kb CACTA superfamily transposable element, transposable element of Dahlia variabilis 1 (Tdv1), was found in the fourth intron of the DvIVS gene of MJW and MJY, and footprints of Tdv1 were detected in the variegated flowers of MJW. It is shown that only one type of DvIVS gene was expressed in MJOr, whereas these plants are likely to have three types of the DvIVS gene. On the basis of these results, the mechanism regulating the formation of orange and yellow ray florets in dahlia is discussed. PMID:21765172

Ohno, Sho; Hosokawa, Munetaka; Hoshino, Atsushi; Kitamura, Yoshikuni; Morita, Yasumasa; Park, Kyeung-II; Nakashima, Akiko; Deguchi, Ayumi; Tatsuzawa, Fumi; Doi, Motoaki; Iida, Shigeru; Yazawa, Susumu

2011-01-01

287

Differential Contribution of Transcription Factors to Arabidopsis thaliana Defense Against Spodoptera littoralis  

PubMed Central

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

Schweizer, Fabian; Bodenhausen, Natacha; Lassueur, Steve; Masclaux, Frederic G.; Reymond, Philippe

2013-01-01

288

Transcription factor AP4 modulates reversible and epigenetic silencing of the Cd4 gene.  

PubMed

CD4 coreceptor expression is negatively regulated through activity of the Cd4 silencer in CD4(-)CD8(-) double-negative (DN) thymocytes and CD8(+) cytotoxic lineage T cells. Whereas Cd4 silencing is reversed during transition from DN to CD4(+)CD8(+) double-positive stages, it is maintained through heritable epigenetic processes following its establishment in mature CD8(+) T cells. We previously demonstrated that the Runx family of transcription factors is required for Cd4 silencing both in DN thymocytes and CD8(+) T cells. However, additional factors that cooperate with Runx proteins in the process of Cd4 silencing remain unknown. To identify collaborating factors, we used microarray and RNAi-based approaches and found the basic helix-loop-helix ZIP transcription factor AP4 to have an important role in Cd4 regulation. AP4 interacts with Runx1 in cells in which Cd4 is silenced, and is required for Cd4 silencing in immature DN thymocytes through binding to the proximal enhancer. Furthermore, although AP4-deficient CD8(+) T cells appeared to normally down-regulate CD4 expression, AP4 deficiency significantly increased the frequency of CD4-expressing effector/memory CD8(+) T cells in mice harboring point mutations in the Cd4 silencer. Our results suggest that AP4 contributes to Cd4 silencing both in DN and CD8(+) T cells by enforcing checkpoints for appropriate timing of CD4 expression and its epigenetic silencing. PMID:21873191

Egawa, Takeshi; Littman, Dan R

2011-09-01

289

Transcription factor AP4 modulates reversible and epigenetic silencing of the Cd4 gene  

PubMed Central

CD4 coreceptor expression is negatively regulated through activity of the Cd4 silencer in CD4–CD8– double-negative (DN) thymocytes and CD8+ cytotoxic lineage T cells. Whereas Cd4 silencing is reversed during transition from DN to CD4+CD8+ double-positive stages, it is maintained through heritable epigenetic processes following its establishment in mature CD8+ T cells. We previously demonstrated that the Runx family of transcription factors is required for Cd4 silencing both in DN thymocytes and CD8+ T cells. However, additional factors that cooperate with Runx proteins in the process of Cd4 silencing remain unknown. To identify collaborating factors, we used microarray and RNAi-based approaches and found the basic helix–loop–helix ZIP transcription factor AP4 to have an important role in Cd4 regulation. AP4 interacts with Runx1 in cells in which Cd4 is silenced, and is required for Cd4 silencing in immature DN thymocytes through binding to the proximal enhancer. Furthermore, although AP4-deficient CD8+ T cells appeared to normally down-regulate CD4 expression, AP4 deficiency significantly increased the frequency of CD4-expressing effector/memory CD8+ T cells in mice harboring point mutations in the Cd4 silencer. Our results suggest that AP4 contributes to Cd4 silencing both in DN and CD8+ T cells by enforcing checkpoints for appropriate timing of CD4 expression and its epigenetic silencing. PMID:21873191

Egawa, Takeshi; Littman, Dan R.

2011-01-01

290

Interplay of the E box, the cyclic AMP response element, and HTF4/HEB in transcriptional regulation of the neurospecific, neurotrophin-inducible vgf gene.  

PubMed Central

vgf is a neurotrophin response-specific, developmentally regulated gene that codes for a neurosecretory polypeptide. Its transcription in neuronal cells is selectively activated by the neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor, and neurotrophin 3, which induce survival and differentiation, and not by epidermal growth factor. We studied a short region of the rat vgf promoter which is essential for its regulated expression. A cyclic AMP response element (CRE) within this region is necessary for NGF induction of vgf transcription. Two sites upstream of CRE, an E box and a CCAAT sequence, bind nuclear protein complexes and are involved in transcriptional control. The E box has a dual role. It acts as an inhibitor in NIH 3T3 fibroblasts, together with a second E box located downstream, and as a stimulator in the NGF-responsive cell line PC12. By expression screening, we have isolated the cDNA for a basic helix-loop-helix transcription factor, a homolog of the HTF4/HEB E protein, that specifically binds the vgf promoter E box. The E protein was present in various cell lines, including PC12 cells, and was a component of a multiprotein nuclear complex that binds the promoter in vitro. The E box and CRE cooperate in binding to this complex, which may be an important determinant for neural cell-specific expression. PMID:9032251

Di Rocco, G; Pennuto, M; Illi, B; Canu, N; Filocamo, G; Trani, E; Rinaldi, A M; Possenti, R; Mandolesi, G; Sirinian, M I; Jucker, R; Levi, A; Nasi, S

1997-01-01

291

Identification and characterization of a T-cell-specific enhancer adjacent to the murine CD4 gene.  

PubMed Central

Expression of the CD4 and CD8 glycoproteins is a tightly regulated process tied to the maturation of functionally distinct classes of thymocytes. Therefore, understanding of the mechanism of expression of the genes encoding CD4 and CD8 is likely to yield important insight into regulation of the differentiated functions of T cells. Here, we report the identification of a T-cell-specific enhancer in a DNase I-hypersensitive region about 13 kb 5' of the transcription initiation site of the murine CD4 gene. Within the minimal enhancer element, at least three nuclear protein binding sites were identified by DNase I footprint analysis. One site contains the consensus motif for TCF-1 alpha/LEF-1, a recently identified HMG box transcription factor primarily expressed in pre-B and T cells. By Southwestern (DNA-protein) blotting and binding competition analyses, the protein binding to this site was found to be indistinguishable from TCF-1 alpha/LEF-1. Mutagenesis of this site resulted in loss of factor binding but had a relatively minor effect on enhancer activity. In contrast, mutations in another site, containing two consensus binding motifs for basic helix-loop-helix proteins, abolished factor binding and dramatically reduced enhancer activity. None of the protein binding sites had activity on its own, suggesting that the CD4 enhancer requires the interaction of multiple regulatory sites. Images PMID:1922061

Sawada, S; Littman, D R

1991-01-01

292

Loss of Singleminded-2s in the Mouse Mammary Gland Induces an Epithelial-Mesenchymal Transition Associated with Up-Regulation of Slug and Matrix Metalloprotease 2? †  

PubMed Central

The short splice variant of the basic helix-loop-helix Per-Arnt-Sim transcription factor Singleminded-2, SIM2s, has been implicated in development and is frequently lost or reduced in primary breast tumors. Here, we show that loss of Sim2s causes aberrant mouse mammary gland ductal development with features suggestive of malignant transformation, including increased proliferation, loss of polarity, down-regulation of E-cadherin, and invasion of the surrounding stroma. Additionally, knockdown of SIM2s in MCF-7 breast cancer cells contributed to an epithelial-mesenchymal transition (EMT) and increased tumorigenesis. In both Sim2?/? mammary glands and SIM2s-depleted MCF7 cells, these changes were associated with increased SLUG and MMP2 levels. SIM2s protein was detectable on the SLUG promoter, and overexpression of SIM2s repressed expression from a SLUG-controlled reporter in a dose-dependent manner. To our knowledge, SIM2s is the first protein shown to bind and repress the SLUG promoter, providing a plausible explanation for the development role and breast tumor-suppressive activity of SIM2s. Together, our results suggest that SIM2s is a key regulator of mammary-ductal development and that loss of SIM2s expression is associated with an invasive, EMT-like phenotype. PMID:18160708

Laffin, Brian; Wellberg, Elizabeth; Kwak, Hyeong-Il; Burghardt, Robert C.; Metz, Richard P.; Gustafson, Tanya; Schedin, Pepper; Porter, Weston W.

2008-01-01

293

Loss of singleminded-2s in the mouse mammary gland induces an epithelial-mesenchymal transition associated with up-regulation of slug and matrix metalloprotease 2.  

PubMed

The short splice variant of the basic helix-loop-helix Per-Arnt-Sim transcription factor Singleminded-2, SIM2s, has been implicated in development and is frequently lost or reduced in primary breast tumors. Here, we show that loss of Sim2s causes aberrant mouse mammary gland ductal development with features suggestive of malignant transformation, including increased proliferation, loss of polarity, down-regulation of E-cadherin, and invasion of the surrounding stroma. Additionally, knockdown of SIM2s in MCF-7 breast cancer cells contributed to an epithelial-mesenchymal transition (EMT) and increased tumorigenesis. In both Sim2(-/-) mammary glands and SIM2s-depleted MCF7 cells, these changes were associated with increased SLUG and MMP2 levels. SIM2s protein was detectable on the SLUG promoter, and overexpression of SIM2s repressed expression from a SLUG-controlled reporter in a dose-dependent manner. To our knowledge, SIM2s is the first protein shown to bind and repress the SLUG promoter, providing a plausible explanation for the development role and breast tumor-suppressive activity of SIM2s. Together, our results suggest that SIM2s is a key regulator of mammary-ductal development and that loss of SIM2s expression is associated with an invasive, EMT-like phenotype. PMID:18160708

Laffin, Brian; Wellberg, Elizabeth; Kwak, Hyeong-Il; Burghardt, Robert C; Metz, Richard P; Gustafson, Tanya; Schedin, Pepper; Porter, Weston W

2008-03-01

294

MyoD induces myogenic differentiation through cooperation of its NH2- and COOH-terminal regions  

PubMed Central

MyoD and Myf5 are basic helix-loop-helix transcription factors that play key but redundant roles in specifying myogenic progenitors during embryogenesis. However, there are functional differences between the two transcription factors that impact myoblast proliferation and differentiation. Target gene activation could be one such difference. We have used microarray and polymerase chain reaction approaches to measure the induction of muscle gene expression by MyoD and Myf5 in an in vitro model. In proliferating cells, MyoD and Myf5 function very similarly to activate the expression of likely growth phase target genes such as L-myc, m-cadherin, Mcpt8, Runx1, Spp1, Six1, IGFBP5, and Chrn?1. MyoD, however, is strikingly more effective than Myf5 at inducing differentiation-phase target genes. This distinction between MyoD and Myf5 results from a novel and unanticipated cooperation between the MyoD NH2- and COOH-terminal regions. Together, these results support the notion that Myf5 functions toward myoblast proliferation, whereas MyoD prepares myoblasts for efficient differentiation. PMID:16275751

Ishibashi, Jeff; Perry, Robert L.; Asakura, Atsushi; Rudnicki, Michael A.

2005-01-01

295

Direct transcriptional induction of Gadd45? by Ascl1 during neuronal differentiation  

PubMed Central

The basic helix-loop-helix transcription factor Ascl1 plays a critical role in the intrinsic genetic program responsible for neuronal differentiation. Here, we describe a novel model system of P19 embryonic carcinoma cells with doxycycline-inducible expression of Ascl1. Microarray hybridization and real-time PCR showed that these cells demonstrated increased expression of many neuronal proteins in a time- and concentration-dependent manner. Interestingly, the gene encoding the cell cycle regulator Gadd45? was increased earliest and to the greatest extent following Ascl1 induction. Here, we provide the first evidence identifying Gadd45? as a direct transcriptional target of Ascl1. Transactivation and chromatin immunoprecipitation assays identified two E-box consensus sites within the Gadd45? promoter necessary for Ascl1 regulation, and demonstrated that Ascl1 is bound to this region within the Gadd45? promoter. Furthermore, we found that overexpression of Gadd45? itself is sufficient to initiate some aspects of neuronal differentiation independent of Ascl1. PMID:20382226

Huang, Holly S.; Kubish, Ginger M.; Redmond, Tanya M.; Turner, David L.; Thompson, Robert C.; Murphy, Geoffrey G.; Uhler, Michael D.

2010-01-01

296

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

PubMed

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

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

2009-05-01

297

Sohlh2 inhibits ovarian cancer cell proliferation by upregulation of p21 and downregulation of cyclin D1.  

PubMed

Spermatogenesis and oogenesis basic helix-loop-helix (bHLH) transcription factor 2 (Sohlh2) functions as a bhlh transcription factor to regulate mouse germ cell differentiation. Our previous data showed that Sohlh2 was highly expressed in human normal tissues, but low level of Sohlh2 was observed in many cancer cell lines, suggesting a possible role of Sohlh2 in tumorigenesis. In this study, we examined this possibility by using immunohistochemistry, MTT, 5-bromo-2-deoxyuridine, clonogenic assay and tumor xenograft techniques. Our results showed that the expression of Sohlh2 was decreased in epithelial ovarian carcinoma (EOC) tissues compared with benign ovarian tumors and ovarian tumors with low malignant potential. Forced expression of Sohlh2 led to a significant reduction in cancer cell proliferation in vitro and tumorigenesis in nude mice. Conversely, silencing of Sohlh2 enhanced ovarian cancer cell proliferation. Furthermore, Sohlh2 had opposite effects on its two direct targets p21 and cyclin D1: overexpression of Sohlh2 upregulated p21 but downregulated cyclin D1 expression. p21 knockdown could reverse the effects of Sohlh2 overexpression on inhibiting cell proliferation, and cyclin D1 knockdown could reverse the effects of Sohlh2 ablation on promoting cell proliferation. Thus, our data indicate that Sohlh2 likely functions as a tumor suppressor in EOCs, which is achieved by inducing p21 expression but repressing cyclin D1 expression. PMID:24858206

Zhang, Haiyu; Zhang, Xiaoli; Ji, Shufang; Hao, Chunyan; Mu, Yulan; Sun, Jinhao; Hao, Jing

2014-08-01

298

Differential methylation of CpG islands within the dermo1 gene promoter in several cancer cell lines.  

PubMed

Inactivation of tumor-related genes by promoter hypermethylation is a common epigenetic event in the development of variety of tumors. Dermo1 (also called twist2) is a novel cancer-related gene which belongs to the basic helix-loop-helix (bHLH) transcription factor family. Herein, we report that dermo1 expression was sporadically abrogated in human cancer cells by transcriptional silencing associated with CpG island promoter hypermethylation. Direct sequencing of bisulfite-modified DNA from a panel of seven human cancer cell lines (HL60, Molm14, MV4-11, RS4:11, MDM-BA231, H358, and H1299) revealed that CpG dinucleotides in the dermo1 promoter were methylated. RT-PCR results demonstrated that dermo1 CpG island hypermethylation was accompanied by a low basal dermo1 expression level. Our data implicate dermo1 as a tumor suppressor gene and a valuable molecular marker for human cancer. PMID:21109964

Mao, Yubin; Toh, Hween-Boon; Ding, Zhijie; Sun, Lifang; Hong, Liang; Chen, Chien-Shing; Wu, Xueji

2011-01-01

299

Regulation of the Drosophila hypoxia-inducible factor alpha Sima by CRM1-dependent nuclear export.  

PubMed

Hypoxia-inducible factor alpha (HIF-alpha) proteins are regulated by oxygen levels through several different mechanisms that include protein stability, transcriptional coactivator recruitment, and subcellular localization. It was previously reported that these transcription factors are mainly nuclear in hypoxia and cytoplasmic in normoxia, but so far the molecular basis of this regulation is unclear. We show here that the Drosophila melanogaster HIF-alpha protein Sima shuttles continuously between the nucleus and the cytoplasm. We identified the relevant nuclear localization signal and two functional nuclear export signals (NESs). These NESs are in the Sima basic helix-loop-helix (bHLH) domain and promote CRM1-dependent nuclear export. Site-directed mutagenesis of either NES provoked Sima nuclear retention and increased transcriptional activity, suggesting that nuclear export contributes to Sima regulation. The identified NESs are conserved and probably functional in the bHLH domains of several bHLH-PAS proteins. We propose that rapid nuclear export of Sima regulates the duration of cellular responses to hypoxia. PMID:18332128

Romero, Nuria M; Irisarri, Maximiliano; Roth, Peggy; Cauerhff, Ana; Samakovlis, Christos; Wappner, Pablo

2008-05-01

300

Regulation of the Drosophila Hypoxia-Inducible Factor ? Sima by CRM1-Dependent Nuclear Export ?  

PubMed Central

Hypoxia-inducible factor ? (HIF-?) proteins are regulated by oxygen levels through several different mechanisms that include protein stability, transcriptional coactivator recruitment, and subcellular localization. It was previously reported that these transcription factors are mainly nuclear in hypoxia and cytoplasmic in normoxia, but so far the molecular basis of this regulation is unclear. We show here that the Drosophila melanogaster HIF-? protein Sima shuttles continuously between the nucleus and the cytoplasm. We identified the relevant nuclear localization signal and two functional nuclear export signals (NESs). These NESs are in the Sima basic helix-loop-helix (bHLH) domain and promote CRM1-dependent nuclear export. Site-directed mutagenesis of either NES provoked Sima nuclear retention and increased transcriptional activity, suggesting that nuclear export contributes to Sima regulation. The identified NESs are conserved and probably functional in the bHLH domains of several bHLH-PAS proteins. We propose that rapid nuclear export of Sima regulates the duration of cellular responses to hypoxia. PMID:18332128

Romero, Nuria M.; Irisarri, Maximiliano; Roth, Peggy; Cauerhff, Ana; Samakovlis, Christos; Wappner, Pablo

2008-01-01

301

An scl gene product lacking the transactivation domain induces bony abnormalities and cooperates with LMO1 to generate T-cell malignancies in transgenic mice.  

PubMed Central

The product of the scl (also called tal-1 or TCL5) gene is a basic domain, helix-loop-helix (bHLH) transcription factor required for the development of hematopoietic cells. Additionally, scl gene disruption and dysregulation, by either chromosomal translocations or a site-specific interstitial deletion whereby 5' regulatory elements of the sil gene become juxtaposed to the body of the scl gene, is associated with T-cell acute lymphoblastic leukemia (ALL) and T-cell lymphoblastic lymphoma. Here we show that an inappropriately expressed scl protein, driven by sil regulatory elements, can cause aggressive T-cell malignancies in collaboration with a misexpressed LMO1 protein, thus recapitulating the situation seen in a subset of human T-cell ALL. Moreover, we show that inappropriately expressed scl can interfere with the development of other tissues derived from mesoderm. Lastly, we show that an scl construct lacking the scl transactivation domain collaborates with misexpressed LMO1, demonstrating that the scl transactivation domain is dispensable for oncogenesis, and supporting the hypothesis that the scl gene product exerts its oncogenic action through a dominant-negative mechanism. PMID:9171354

Aplan, P D; Jones, C A; Chervinsky, D S; Zhao, X; Ellsworth, M; Wu, C; McGuire, E A; Gross, K W

1997-01-01

302

Origins of enhancer sequences of recombinant murine leukemia viruses from spontaneous B- and T-cell lymphomas of CWD mice.  

PubMed Central

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. Images PMID:8189515

Massey, A C; Lawrenz-Smith, S C; Innes, D J; Thomas, C Y

1994-01-01

303

Functional specialization of stomatal bHLHs through modification of DNA-binding and phosphoregulation potential  

PubMed Central

Transcription factor duplication events and subsequent specialization can drive evolution by facilitating biological innovation and developmental complexity. Identification of sequences that confer distinct biochemical function in vivo is an important step in understanding how related factors could refine specific developmental processes over time. Functional analysis of the basic helix–loop–helix (bHLH) protein SPEECHLESS, one of three closely related transcription factors required for stomatal lineage progression in Arabidopsis thaliana, allowed a dissection of motifs associated with specific developmental outputs. Phosphorylated residues, shown previously to quantitatively affect activity, also allow a qualitative shift in function between division and cell fate-promoting activities. Our data also provide surprising evidence that, despite deep sequence conservation in DNA-binding domains, the functional requirement for these domains has diverged, with the three stomatal bHLHs exhibiting absolute, partial, or no requirements for DNA-binding residues for their in vivo activities. Using these data, we build a plausible model describing how the current unique and overlapping roles of these proteins might have evolved from a single ancestral protein. PMID:25304637

Davies, Kelli A.; Bergmann, Dominique C.

2014-01-01

304

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

SciTech Connect

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

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

1996-07-01

305

The expression of antiapoptotic protein survivin is transcriptionally upregulated by DEC1 primarily through multiple sp1 binding sites in the proximal promoter  

PubMed Central

Human differentially expressed in chondrocytes (DEC), mouse stimulated with retinoic acid and rat split and hairy related proteins constitute a structurally distinct class of the basic helix-loop-helix proteins. DEC1is abundantly expressed in tumors and protects against apoptosis induced by serum starvation. In this study, we report that DEC1 antiapoptosis is achieved by inducing survivin, an antiapoptotic protein. In paired tumor–normal tissues, survivin and DEC1 exhibited a paralleled expression pattern. Tetracycline-induced expression of DEC1 in stable lines proportionally increased the expression of survivin. In reporter assays, DEC1 transactivated the survivin promoter but repressed the DEC2 promoter. In contrast to the repression, the activation was delayed and varied depending on serum concentrations and cycle blockers. Studies with reporter mutants located, in the survivin promoter, two Sp1 sites that supported DEC1 transactivation. Electrophoretic mobility shift assay and chromatin immunoprecipitation detected the presence of DEC1 in the survivin promoter. These findings establish that the survivin gene is a transcription target of DEC1, and induction of survivin is at least in part responsible for DEC1 antiapoptosis. PMID:16462771

Li, Y; Xie, M; Yang, J; Yang, D; Deng, R; Wan, Y; Yan, B

2014-01-01

306

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

PubMed Central

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

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

2014-01-01

307

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

PubMed Central

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

Reymond, Mathieu C.; Brunoud, Geraldine; Chauvet, Aurelie; Martinez-Garcia, Jaime F.; Martin-Magniette, Marie-Laure; Moneger, Francoise; Scutt, Charles P.

2012-01-01

308

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

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

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

2011-01-01

309

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

PubMed

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

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

2005-09-27

310

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

PubMed

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

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

2014-05-16

311

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

PubMed

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

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

2014-07-18

312

Restricted leucine zipper dimerization and specificity of DNA recognition of the melanocyte master regulator MITF  

PubMed Central

Microphthalmia-associated transcription factor (MITF) is a master regulator of melanocyte development and an important oncogene in melanoma. MITF heterodimeric assembly with related basic helix–loop–helix leucine zipper transcription factors is highly restricted, and its binding profile to cognate DNA sequences is distinct. Here, we determined the crystal structure of MITF in its apo conformation and in the presence of two related DNA response elements, the E-box and M-box. In addition, we investigated mouse and human Mitf mutations to dissect the functional significance of structural features. Owing to an unusual three-residue shift in the leucine zipper register, the MITF homodimer shows a marked kink in one of the two zipper helices to allow an out-of-register assembly. Removal of this insertion relieves restricted heterodimerization by MITF and permits assembly with the transcription factor MAX. Binding of MITF to the M-box motif is mediated by an unusual nonpolar interaction by Ile212, a residue that is mutated in mice and humans with Waardenburg syndrome. As several related transcription factors have low affinity for the M-box sequence, our analysis unravels how these proteins discriminate between similar target sequences. Our data provide a rational basis for targeting MITF in the treatment of important hereditary diseases and cancer. PMID:23207919

Pogenberg, Vivian; Ogmundsdottir, Margret H; Bergsteinsdottir, Kristin; Schepsky, Alexander; Phung, Bengt; Deineko, Viktor; Milewski, Morlin; Steingrimsson, Eirikur; Wilmanns, Matthias

2012-01-01

313

Molecular characterization and mapping of ATOH7, a human atonal homolog with a predicted role in retinal ganglion cell development  

PubMed Central

The human ATOH7 gene encodes a basic helix-loop-helix (bHLH) transcription factor that is highly similar to Drosophila Atonal within the conserved bHLH domain. The ATOH7 coding region is contained within a single exon. We mapped ATOH7 to Chromosome (Chr) 10q21.3–22.1, a region syntenic to the segment of mouse Chr 10 where Atoh7 (formerly Math5) is located. The evolutionary relationship between ATOH7 and other atonal homologs was investigated using parsimony analysis. A direct comparison of ATH5/7 and ATH1 protein subgroups to Atonal also revealed a nonrandom distribution of amino acid changes across the bHLH domain, which may be related to their separate visual and proprioceptive sensory functions. Among bHLH genes, ATOH7 is most closely related to Atoh7. This sequence conservation extends significantly beyond the coding region. We define blocks of strong homology in flanking human and mouse genomic DNA, which are likely to include cis regulatory elements. Because targeted deletion of Atoh7 causes optic nerve agenesis in mice, we propose ATOH7 as a candidate for human optic nerve aplasia and related clinical syndromes. PMID:11889557

Brown, Nadean L.; Dagenais, Susan L.; Chen, Chuan-Min; Glaser, Tom

2008-01-01

314

Target-dependent inhibition of sympathetic neuron growth via modulation of a BMP signaling pathway  

PubMed Central

Target-derived factors modulate many aspects of peripheral neuron development including neuronal growth, survival, and maturation. Less is known about how initial target contact regulates changes in gene expression associated with these developmental processes. One early consequence of contact between growing sympathetic neurons and their cardiac myocyte targets is the inhibition of neuronal outgrowth. Analysis of neuronal gene expression following this contact revealed coordinate regulation of a bone morphogenetic protein (BMP)-dependent growth pathway in which basic helix-loop-helix transcription factors and downstream neurofilament expression contribute to the growth dynamics of developing sympathetic neurons. BMP2 had dose-dependent growth promoting effects on sympathetic neurons cultured in the absence, but not the presence, of myocyte targets, suggesting that target contact alters neuronal responses to BMP signaling. Target contact also induced the expression of matrix Gla protein (MGP), a regulator of BMP function in the vascular system. Increased MGP expression inhibited BMP-dependent neuronal growth and MGP expression increased in sympathetic neurons during the period of target contact in vivo. These experiments establish MGP as a novel regulator of BMP function in the nervous system, and define developmental transitions in BMP responses during sympathetic development. PMID:18272145

Moon, Jung-Il; Birren, Susan J.

2008-01-01

315

Role of AHR, AHRR and ARNT in response to dioxin-like PCBs in Spaurus aurata.  

PubMed

The aryl hydrocarbon receptor (AHR) mediates a variety of biological responses to ubiquitous dioxin and PCB dioxin-like. AHR together with ARNT, AHRR, represent a novel basic helix-loop-helix/PAS family of transcriptional regulators. Their interplay may affect the xenobiotic response. The aim of this study was to investigate, by histological, immunohistochemical investigations and western-blot analysis, the expression of AHR, ARNT and AHRR in liver of seabrem (Spaurus aurata) after exposure at different time to dioxin-like PCB126 in order to deep the knowledge about their specific role. The findings showed a significant increase of AHR and ARNT expression in juvenile fishes after 12 h than control group. The induction of AHR and ARNT is also significant at 24 and 72 hours compared to the control group. Furthemore, induction of AHRR expression has proved to increase both 12 h but this induction does not seem significant to 24 and 72 hours. The most important data of this work is that the induction of AHRR, when the action of the toxic persistence substances, as dioxin and PCB-126, it is not enough to reduce AHR signaling and thus its hyperactivation leads to toxic effects in seabrem (Spaurus aurata). All this confirms the importance of AHR ligands as new class of drugs that can be directed against severe disease such as cancer. PMID:25060310

Calò, Margherita; Licata, Patrizia; Bitto, Alessandra; Lo Cascio, Patrizia; Interdonato, Monica; Altavilla, Domenica

2014-12-01

316

Inhibitor of differentiation 1 (Id1) expression attenuates the degree of TiO2-induced cytotoxicity in H1299 non-small cell lung cancer cells.  

PubMed

The inhibitor of differentiation (Id) family of genes, which encodes negative regulators of basic helix-loop-helix transcription factors, has been implicated in diverse cellular processes such as proliferation, apoptosis, differentiation, and migration. However, the specific role of Id1 in titanium dioxide (TiO2)-induced lung injury has not been investigated. In the present study, we investigated whether TiO2 induces apoptosis in H1299 lung cancer cells and by which pathways. Based on the results of the LDH assay, dual staining with Annexin V-FITC and propidium iodide (PI), and RT-PCR analysis of apoptosis-related gene expression, TiO2 caused a dose- and time-dependent decrease in cell viability and appeared to involve both necrosis and apoptosis. Furthermore, Id1 expression was significantly reduced in TiO2-treated cells compared with control cells. To further investigate the functional role of Id1, cells were transduced with a recombinant adenovirus expressing Id1, and the effects on sensitivity to TiO2 were analyzed. Id1 overexpression led to the enhancement of cellular proliferation and reduced the sensitivity of H1299 cells to TiO2. Our results indicate that Id1 expression attenuates the degree of TiO2-induced cytotoxicity in lung cells. PMID:19486931

Lee, Young Sook; Yoon, Seokjoo; Yoon, Hea Jin; Lee, Kyuhong; Yoon, Hyoun Kyoung; Lee, Jeung-Hoon; Song, Chang Woo

2009-09-28

317

The Intracellular Localization of ID2 Expression Has a Predictive Value in Non Small Cell Lung Cancer  

PubMed Central

Background ID2 is a member of a subclass of transcription regulators belonging to the general bHLH (basic-helix-loop-helix) family of transcription factors. In normal cells, ID2 is responsible for regulating the balance between proliferation and differentiation. More recent studies have demonstrated that ID2 is involved in tumor progression in several cancer types such as prostate or breast. Methodology/Principal Findings In this work, we investigated, for the first time, the relationship between the expression of ID2 in non-small cell lung cancer (NSCLC) patients and the clinicopathological features and prognosis of these patients. Immunohistochemistry was performed on tissue microarrays, which included 62 NSCLC tumors. In malignant tissues, ID2 expression has been detected in both the nuclear and cytoplasmic compartments, but we have demonstrated that only nuclear expression of ID2 is inversely correlated with the differentiation grade of the tumor (p?=?0.007). Interestingly, among patients with poorly differentiated tumors, high nuclear expression of ID2 was an independent and unfavorable prognostic factor for survival (p?=?0.036). Conclusions These results suggest that ID2 could be involved in tumor dedifferentiation processes of NSCLC, and could be used as prognostic marker for patients with poorly differentiated tumors. PMID:19129913

Rollin, Jerome; Blechet, Claire; Regina, Sandra; Tenenhaus, Arthur; Guyetant, Serge; Gidrol, Xavier

2009-01-01

318

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

PubMed Central

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

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

319

Regulation of cell divisions and differentiation by MALE STERILITY32 is required for anther development in maize  

PubMed Central

Summary Male fertility in flowering plants relies on proper division and differentiation of cells in the anther, a process that gives rise to four somatic layers surrounding central germinal cells. The maize gene male sterility32 (ms32) encodes a basic helix–loop–helix (bHLH) transcription factor, which functions as an important regulator of both division and differentiation during anther development. After the four somatic cell layers are generated properly through successive periclinal divisions, in the ms32 mutant, tapetal precursor cells fail to differentiate, and, instead, undergo additional periclinal divisions to form extra layers of cells. These cells become vacuolated and expand, and lead to failure in pollen mother cell development. ms32 expression is specific to the pre-meiotic anthers and is distributed initially broadly in the four lobes, but as the anther develops, its expression becomes restricted to the innermost somatic layer, the tapetum. The ms32-ref mac1-1 double mutant is unable to form tapetal precursors and also exhibits excessive somatic proliferation leading to numerous, disorganized cell layers, suggesting a synergistic interaction between ms32 and mac1. Altogether, our results show that MS32 is a major regulator in maize anther development that promotes tapetum differentiation and inhibits periclinal division once a tapetal cell is specified. PMID:24033746

Moon, Jihyun; Skibbe, David; Timofejeva, Ljudmilla; Rachel Wang, Chung-Ju; Kelliher, Timothy; Kremling, Karl; Walbot, Virginia; Zacheus Cande, William

2014-01-01

320

Differential responsiveness of distinct retinal domains to Atoh7  

PubMed Central

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

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

2014-01-01

321

The putative transcription factor CaRtg3 is involved in tolerance to cations and antifungal drugs as well as serum-induced filamentation in Candida albicans.  

PubMed

The activated retrograde (RTG) pathway controls transcription of target genes through a heterodimer of transcription factors, Rtg1 and Rtg3, in Saccharomyces cerevisiae. Here, we have identified the sole homologous gene CaRTG3 that encodes a protein of 520 amino acids with characteristics of the basic helix-loop-helix/leucine zipper (bHLH/Zip) family in Candida albicans. Deletion of CaRTG3 results in C. albicans cells being sensitive to high concentrations of calcium and lithium cations as well as sodium dodecyl sulfate and activates the calcium/calcineurin signaling pathway in C. albicans cells. CaRTG3 is also involved in the tolerance of C. albicans cells to the antifungal drugs azoles and terbinafine, but not to the antifungal drugs casponfungin and amphotericin B as well as the cell-wall-damaging reagents Calcoflour White and Congo red. In contrast to ScRtg3, CaRtg3 is not involved in the osmolar response and is constitutively localized in the nucleus. However, deletion of CaRTG3 results in a delay in serum-induced filamentation of C. albicans cells. Therefore, CaRtg3 plays a role in tolerance to cations and antifungal drugs as well as serum-induced filamentation in C. albicans. PMID:24606409

Yan, Hongbo; Zhao, Yunying; Jiang, Linghuo

2014-06-01

322

Pyramidal neurons of upper cortical layers generated by NEX-positive progenitor cells in the subventricular zone  

PubMed Central

The generation of pyramidal neurons in the mammalian neocortex has been attributed to proliferating progenitor cells within the ventricular zone (VZ). Recently, the subventricular zone (SVZ) has been recognized as a possible source of migratory neurons in brain slice preparations, but the relevance of these observations for the developing neocortex in vivo remains to be defined. Here, we demonstrate that a subset of progenitor cells within the SVZ of the mouse neocortex can be molecularly defined by Cre recombinase expression under control of the NEX/Math2 locus, a neuronal basic helix-loop-helix gene that by itself is dispensable for cortical development. NEX-positive progenitors are generated by VZ cells, move into the SVZ, and undergo multiple asymmetrical and symmetrical cell divisions that produce a fraction of the neurons in the upper cortical layers. Our data suggest that NEX-positive progenitors within the SVZ are committed to a glutamatergic neuronal fate and have evolved to expand the number of cortical output neurons that is characteristic for the mammalian forebrain. PMID:16284248

Wu, Sheng-Xi; Goebbels, Sandra; Nakamura, Kouichi; Nakamura, Kazuhiro; Kometani, Kouhei; Minato, Nagahiro; Kaneko, Takeshi; Nave, Klaus-Armin; Tamamaki, Nobuaki

2005-01-01

323

NeuroD1 is required for survival of photoreceptors but not pinealocytes: Results from targeted gene deletion studies  

PubMed Central

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

Ochocinska, Margaret J.; Munoz, 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

324

Neurogenin 2 Mediates Amyloid-? Precursor Protein-stimulated Neurogenesis.  

PubMed

Amyloid-? precursor protein (APP) is well studied for its role in Alzheimer disease, although its normal function remains uncertain. It has been reported that APP stimulates the proliferation and neuronal differentiation of neural stem/progenitor cells (NSPCs). In this study we examined the role of APP in NSPC differentiation. To identify proteins that may mediate the effect of APP on NSPC differentiation, we used a gene array approach to find genes whose expression correlated with APP-induced neurogenesis. We found that the expression of neurogenin 2 (Ngn2), a basic helix-loop-helix transcription factor, was significantly down-regulated in NSPCs from APP knock-out mice (APPKO) and increased in APP transgenic (Tg2576) mice. Ngn2 overexpression in APPKO NSPCs promoted neuronal differentiation, whereas siRNA knockdown of Ngn2 expression in wild-type NSPCs decreased neuronal differentiation. The results demonstrate that APP-stimulated neuronal differentiation of NSPCs is mediated by Ngn2. PMID:25217641

Bolós, Marta; Hu, Yanling; Young, Kaylene M; Foa, Lisa; Small, David H

2014-11-01

325

Oligodendrocytes Are a Major Target of the Toxicity of Spongiogenic Murine Retroviruses  

PubMed Central

The neurovirulent retroviruses FrCasE and Moloney MLV-ts1 cause noninflammatory spongiform neurodegeneration in mice, manifested clinically by progressive spasticity and paralysis. Neurons have been thought to be the primary target of toxicity of these viruses. However the neurons themselves appear not to be infected, and the possible indirect mechanisms driving the neuronal toxicity have remained enigmatic. Here we have re-examined the cells that are damaged by these viruses, using lineage-specific markers. Surprisingly, these cells expressed the basic helix-loop-helix transcription factor Olig2, placing them in the oligodendrocyte lineage. Olig2+ cells were found to be infected, and many of these cells exhibited focal cytoplasmic vacuolation, suggesting that infection by spongiogenic retroviruses is directly toxic to these cells. As cytoplasmic vacuolation progressed, however, signs of viral protein expression appeared to wane, although residual viral RNA was detectable by in situ hybridization. Cells with the most advanced cytoplasmic effacement expressed the C/EBP-homologous protein (CHOP). This protein is up-regulated as a late event in a cellular response termed the integrated stress response. This observation may link the cellular pathology observed in the brain with cellular stress responses known to be induced by these viruses. The relevance of these observations to oligodendropathy in humans is discussed. PMID:16936275

Clase, Amanda C.; Dimcheff, Derek E.; Favara, Cynthia; Dorward, David; McAtee, Frank J.; Parrie, Lindsay E.; Ron, David; Portis, John L.

2006-01-01

326

In vivo Atoh1 targetome reveals how a proneural transcription factor regulates cerebellar development  

PubMed Central

The proneural, basic helix–loop–helix transcription factor Atoh1 governs the development of numerous key neuronal subtypes, such as cerebellar granule and brainstem neurons, inner ear hair cells, and several neurons of the proprioceptive system, as well as diverse nonneuronal cell types, such as Merkel cells and intestinal secretory lineages. However, the mere handful of targets that have been identified barely begin to account for Atoh1’s astonishing range of functions, which also encompasses seemingly paradoxical activities, such as promoting cell proliferation and medulloblastoma formation in the cerebellum and inducing cell cycle exit and suppressing tumorigenesis in the intestine. We used a multipronged approach to create a comprehensive, unbiased list of over 600 direct Atoh1 target genes in the postnatal cerebellum. We found that Atoh1 binds to a 10 nucleotide motif (AtEAM) to directly regulate genes involved in migration, cell adhesion, metabolism, and other previously unsuspected functions. This study expands current thinking about the transcriptional activities driving neuronal differentiation and provides a framework for further neurodevelopmental studies. PMID:21300888

Klisch, Tiemo J.; Xi, Yuanxin; Flora, Adriano; Wang, Liguo; Li, Wei; Zoghbi, Huda Y.

2011-01-01

327

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

PubMed Central

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

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

2013-01-01

328

Tal2 expression is induced by all-trans retinoic acid in P19 cells prior to acquisition of neural fate.  

PubMed

TAL2 is a member of the basic helix-loop-helix family and is essential for the normal development of the mouse brain. However, the function of TAL2 during brain development is unclear. P19 cells are pluripotent mouse embryonal carcinoma cells that adopt neural fates upon exposure to all-trans retinoic acid (atRA) and culture in suspension. We found that the expression of Tal2 gene was induced in P19 cells after addition of atRA in suspension culture. Tal2 expression was detected within 3?h after the induction, and had nearly returned to basal levels by 24?h. When GFP-tagged TAL2 (GFP-TAL2) was expressed in P19 cells, we observed GFP-TAL2 in the nucleus. Moreover, we showed that atRA and retinoic acid receptor ? regulated Tal2 expression. These results demonstrate for the first time that atRA induces Tal2 expression in P19 cells, and suggest that TAL2 commits to the acquisition of neural fate in brain development. PMID:24816818

Kobayashi, Takanobu; Komori, Rie; Ishida, Kiyoshi; Kino, Katsuhito; Tanuma, Sei-ichi; Miyazawa, Hiroshi

2014-01-01

329

Tal2 expression is induced by all-trans retinoic acid in P19 cells prior to acquisition of neural fate  

PubMed Central

TAL2 is a member of the basic helix-loop-helix family and is essential for the normal development of the mouse brain. However, the function of TAL2 during brain development is unclear. P19 cells are pluripotent mouse embryonal carcinoma cells that adopt neural fates upon exposure to all-trans retinoic acid (atRA) and culture in suspension. We found that the expression of Tal2 gene was induced in P19 cells after addition of atRA in suspension culture. Tal2 expression was detected within 3?h after the induction, and had nearly returned to basal levels by 24?h. When GFP-tagged TAL2 (GFP-TAL2) was expressed in P19 cells, we observed GFP-TAL2 in the nucleus. Moreover, we showed that atRA and retinoic acid receptor ? regulated Tal2 expression. These results demonstrate for the first time that atRA induces Tal2 expression in P19 cells, and suggest that TAL2 commits to the acquisition of neural fate in brain development. PMID:24816818

Kobayashi, Takanobu; Komori, Rie; Ishida, Kiyoshi; Kino, Katsuhito; Tanuma, Sei-ichi; Miyazawa, Hiroshi

2014-01-01

330

The SCL +40 Enhancer Targets the Midbrain Together with Primitive and Definitive Hematopoiesis and Is Regulated by SCL and GATA Proteins?  

PubMed Central

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

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

2007-01-01

331

Epstein-Barr virus latent membrane protein 1 (LMP1) upregulates Id1 expression in nasopharyngeal epithelial cells.  

PubMed

Nasopharyngeal carcinoma is closely associated with Epstein-Barr virus (EBV) infection. The EBV-encoded LMP1 has cell transformation property. It suppresses cellular senescence and enhances cell survival in various cell types. Many of the downstream events of LMP1 expression are mediated through its ability to activate NF-kappaB. In this study, we report a novel function of LMP1 to induce Id1 expression in nasopharyngeal epithelial cells (NP69) and human embryonal kidney cells (HEK293). The Id1 is a basic helix-loop-helix (bHLH) protein and a negative transcriptional regulator of p16(INK4a). Expression of Id1 facilitates cellular immortalization and stimulates cell proliferation. With the combination of both specific chemical inhibitors and genetic inhibitors of cell signaling, we showed that induction of Id1 by LMP1 was dependent on its NF-kappaB activation domain at the carboxy-terminal region, CTAR1 and CTAR2. Induction of Id1 by LMP1 may facilitate clonal expansion of premalignant nasopharyngeal epithelial cells infected with EBV and may promote their malignant transformation. PMID:15064751

Li, H M; Zhuang, Z H; Wang, Q; Pang, J C S; Wang, X H; Wong, H L; Feng, H C; Jin, D Y; Ling, M T; Wong, Y C; Eliopoulos, A G; Young, L S; Huang, D P; Tsao, S W

2004-05-27

332

Ptf1a determines horizontal and amacrine cell fates during mouse retinal development.  

PubMed

The vertebrate neural retina comprises six classes of neurons and one class of glial cells, all derived from a population of multipotent progenitors. There is little information on the molecular mechanisms governing the specification of cell type identity from multipotent progenitors in the developing retina. We report that Ptf1a, a basic-helix-loop-helix (bHLH) transcription factor, is transiently expressed by post-mitotic precursors in the developing mouse retina. Recombination-based lineage tracing analysis in vivo revealed that Ptf1a expression marks retinal precursors with competence to exclusively produce horizontal and amacrine neurons. Inactivation of Ptf1a leads to a fate-switch in these precursors that causes them to adopt a ganglion cell fate. This mis-specification of neurons results in a complete loss of horizontal cells, a profound decrease of amacrine cells and an increase in ganglion cells. Furthermore, we identify Ptf1a as a primary downstream target for Foxn4, a forkhead transcription factor involved in the genesis of horizontal and amacrine neurons. These data, together with the previous findings on Foxn4, provide a model in which the Foxn4-Ptf1a pathway plays a central role in directing the differentiation of retinal progenitors towards horizontal and amacrine cell fates. PMID:17075007

Fujitani, Yoshio; Fujitani, Shuko; Luo, Huijun; Qiu, Feng; Burlison, Jared; Long, Qiaoming; Kawaguchi, Yoshiya; Edlund, Helena; MacDonald, Raymond J; Furukawa, Takahisa; Fujikado, Takashi; Magnuson, Mark A; Xiang, Mengqing; Wright, Christopher V E

2006-11-01

333

The bHLH transcription factor hand is required for proper wing heart formation in Drosophila.  

PubMed

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, ?-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

Tögel, Markus; Meyer, Heiko; Lehmacher, Christine; Heinisch, Jürgen J; Pass, Günther; Paululat, Achim

2013-09-15

334

A Role for Id2 in Regulating Photic Entrainment of the Mammalian Circadian System  

PubMed Central

Summary Inhibitor of DNA binding genes (Id1–Id4) encode helix-loop-helix (HLH) transcriptional repressors associated with development and tumorigenesis [1, 2], but little is known concerning the function(s) of these genes in normal adult animals. Id2 was identified in DNA microarray screens for rhythmically expressed genes [3–5], and further analysis revealed a circadian pattern of expression of all four Id genes in multiple tissues including the suprachiasmatic nucleus. To explore an in vivo function, we generated and characterized deletion mutations of Id2 and of Id4. Id2?/? mice exhibit abnormally rapid entrainment and an increase in the magnitude of the phase shift of the pacemaker. A significant proportion of mice also exhibit disrupted rhythms when maintained under constant darkness. Conversely, Id4?/? mice did not exhibit a noticeable circadian phenotype. In vitro studies using an mPer1 and an AVP promoter reporter revealed the potential for ID1, ID2, and ID3 proteins to interact with the canonical basic HLH clock proteins BMAL1 and CLOCK. These data suggest that the Id genes may be important for entrainment and operation of the mammalian circadian system, potentially acting through BMAL1 and CLOCK targets. PMID:19217292

Duffield, Giles E.; Watson, Nathan P.; Mantani, Akio; Peirson, Stuart N.; Robles-Murguia, Maricela; Loros, Jennifer J.; Israel, Mark A.; Dunlap, Jay C.

2009-01-01

335

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

PubMed Central

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

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

2012-01-01

336

Essential Roles of Da Transactivation Domains in Neurogenesis and in E(spl)-Mediated Repression  

PubMed Central

E proteins are a special class of basic helix-loop-helix (bHLH) proteins that heterodimerize with many bHLH activators to regulate developmental decisions, such as myogenesis and neurogenesis. Daughterless (Da) is the sole E protein in Drosophila and is ubiquitously expressed. We have characterized two transcription activation domains (TADs) in Da, called activation domain 1 (AD1) and loop-helix (LH), and have evaluated their roles in promoting peripheral neurogenesis. In this context, Da heterodimerizes with proneural proteins, such as Scute (Sc), which is dynamically expressed and also contributes a TAD. We found that either one of the Da TADs in the Da/Sc complex is sufficient to promote neurogenesis, whereas the Sc TAD is incapable of doing so. Besides its transcriptional activation role, the Da AD1 domain serves as an interaction platform for E(spl) proteins, bHLH-Orange family repressors which antagonize Da/Sc function. We show that the E(spl) Orange domain is needed for this interaction and strongly contributes to the antiproneural activity of E(spl) proteins. We present a mechanistic model on the interplay of these bHLH factors in the context of neural fate assignment. PMID:22949507

Zarifi, Ioanna; Kiparaki, Marianthi; Koumbanakis, Konstantinos A.; Giagtzoglou, Nikolaos; Zacharioudaki, Evanthia; Alexiadis, Anastasios; Livadaras, Ioannis

2012-01-01

337

Roles of bHLH genes in neural stem cell differentiation  

SciTech Connect

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.

Kageyama, Ryoichiro [Institute for Virus Research, Kyoto University, Shogoin-Kawahara, Sakyo-ku, Kyoto 606-8507 (Japan)]. E-mail: rkageyam@virus.kyoto-u.ac.jp; Ohtsuka, Toshiyuki [Institute for Virus Research, Kyoto University, Shogoin-Kawahara, Sakyo-ku, Kyoto 606-8507 (Japan); Hatakeyama, Jun [Institute for Virus Research, Kyoto University, Shogoin-Kawahara, Sakyo-ku, Kyoto 606-8507 (Japan); Ohsawa, Ryosuke [Institute for Virus Research, Kyoto University, Shogoin-Kawahara, Sakyo-ku, Kyoto 606-8507 (Japan)

2005-06-10

338

Induction of neural differentiation by the transcription factor neuroD2.  

PubMed

Pro-neural basic helix loop helix (bHLH) transcription factors are involved in many aspects of normal neuronal development, and over-expression of genes for several of these factors has been shown to induce aspects of neuronal differentiation in cell lines and stem cells. Here we show that over-expression of NeuroD2 (ND2), Neurogenin1 and 2 leads to morphological differentiation of N18-RE-105 neuroblastoma cells and increased expression of synaptic proteins. Particularly ND2 induced neurite formation and increases in the expression of synaptic proteins such as synaptotagmin, that is not expressed normally in this cell type, as well as the redistribution of another synaptic protein, SNAP25, to a cell membrane location. Infection of human neural progenitor cells using adeno associated viral (AAV) vectors also promoted neuronal differentiation. Over-expressing cells demonstrated a significant increase in the neuron specific form of tubulin as well as increased expression of synaptotagmin. Genetic modification of neural progenitor cell with bHLH factors such as ND2 may be a viable strategy to enhance differentiation of these cells into replacement neurons for human disease. PMID:22197973

Messmer, Kirsten; Shen, Wei-Bin; Remington, Mary; Fishman, Paul S

2012-04-01

339

Pdx1 and USF transcription factors co-ordinately regulate Alx3 gene expression in pancreatic ?-cells.  

PubMed

Alterations in transcription factors expressed in insulin-producing islet ?-cells generate pancreatic dysfunction leading to diabetes. The homeodomain transcription factor Alx3 (aristaless-like homeobox 3) expressed in pancreatic islets participates in the regulated expression of several islet genes, and its deficiency in mice leads to islet cell apoptosis and glucose intolerance. In the present study, we investigated the mechanisms that regulate expression of Alx3 in pancreatic islets at the transcriptional level. We found that the Alx3 promoter contains at least eight putative regulatory elements with an E-box consensus sequence, three of which were determined to be functional and required for Alx3 promoter activity by mutational analysis in transfected MIN6 ?-cells. We determined that these E-box elements are recognized by the basic helix-loop-helix transcription factors USF1 (upstream stimulatory factor 1) and USF2. We also identified a highly conserved A-box in the Alx3 promoter that is recognized by the islet-specific transcription factor Pdx1 (pancreatic and duodenal homeobox 1). Pdx1-mediated transactivation of the Alx3 promoter requires the integrity of the three functional E-boxes and the co-operation with USF transcription factors bound to them. The results from the present study indicate that Pdx1 contributes to the transcriptional transactivation of Alx3 in pancreatic ?-cells by acting in co-ordination with USF1 and USF2. PMID:25040025

Fernández-Pérez, Antonio; Vallejo, Mario

2014-10-15

340

Twist1 Controls a Cell-Specification Switch Governing Cell Fate Decisions within the Cardiac Neural Crest  

PubMed Central

Neural crest cells are multipotent progenitor cells that can generate both ectodermal cell types, such as neurons, and mesodermal cell types, such as smooth muscle. The mechanisms controlling this cell fate choice are not known. The basic Helix-loop-Helix (bHLH) transcription factor Twist1 is expressed throughout the migratory and post-migratory cardiac neural crest. Twist1 ablation or mutation of the Twist-box causes differentiation of ectopic neuronal cells, which molecularly resemble sympathetic ganglia, in the cardiac outflow tract. Twist1 interacts with the pro-neural factor Sox10 via its Twist-box domain and binds to the Phox2b promoter to repress transcriptional activity. Mesodermal cardiac neural crest trans-differentiation into ectodermal sympathetic ganglia-like neurons is dependent upon Phox2b function. Ectopic Twist1 expression in neural crest precursors disrupts sympathetic neurogenesis. These data demonstrate that Twist1 functions in post-migratory neural crest cells to repress pro-neural factors and thereby regulate cell fate determination between ectodermal and mesodermal lineages. PMID:23555309

Vincentz, Joshua W.; Firulli, Beth A.; Lin, Andrea; Spicer, Douglas B.; Howard, Marthe J.; Firulli, Anthony B.

2013-01-01

341

TWIST is Expressed in Human Gliomas and Promotes Invasion1  

PubMed Central

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

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

2005-01-01

342

Structural Basis for LMO2-Driven Recruitment of the SCL:E47bHLH Heterodimer to Hematopoietic-Specific Transcriptional Targets  

PubMed Central

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

El Omari, Kamel; Hoosdally, Sarah J.; Tuladhar, Kapil; Karia, Dimple; Hall-Ponsele, Elisa; Platonova, Olga; Vyas, Paresh; Patient, Roger; Porcher, Catherine; Mancini, Erika J.

2013-01-01

343

Specific inactivation of Twist1 in the mandibular arch neural crest cells affects the development of the ramus and reveals interactions with Hand2  

PubMed Central

Background The basic Helix-Loop-Helix (bHLH) transcription factor Twist1 fulfills an essential function in neural crest cell formation, migration and survival and is associated with the craniosynostic Saethre-Chotzen syndrome in humans. However, its functions during mandibular development, when it may interact with other bHLH transcription factors like Hand2, are unknown since mice homozygous for the Twist1 null mutation die in early embryogenesis. To determine the role of Twist1 during mandibular development, we used the Hand2-Cre transgene to conditionally inactivate the gene in the neural crest cells populating the mandibular pharyngeal arch. Results The mutant mice exhibited a spectrum of craniofacial anomalies, including mandibular hypoplasia, altered middle ear development, and cleft palate. It appears that Twist1 is essential for the survival of the neural crest cells involved in the development of the mandibular ramal elements. Twist1 plays a role in molar development and cusp formation by participating in the reciprocal signaling needed for the formation of the enamel knot. This gene is also needed to control the ossification of the mandible, a redundant role shared with Hand2. Conclusion Twist1, along with Hand2, is essential for the proximo-distal patterning and development of the mandible and ossification. PMID:22411303

Zhang, Yanping; Blackwell, Evan L.; McKnight, Mitchell T.; Knutsen, Gregory R.; Vu, Wendy T.; Ruest, L. Bruno

2012-01-01

344

Molecular cloning and expression profile of sex-specific genes, Figla and Dmrt1, in the protogynous hermaphroditic fish, Halichoeres poecilopterus.  

PubMed

The genes folliculogenesis specific basic helix-loop-helix (facor in the germline alpha, Figla) and doublesex and mab-3 related transcription factor 1 (Dmrt1) are female- and male-specific genes that play key roles in sex differentiation. To obtain a better understanding of the molecular mechanisms underlying female-to-male sex change, we cloned the cDNAs of these genes from an ovary and a testis of the protogynus wrasse, Halichoeres poecilopterus. This fish has two isoforms of Dmrt1, Dmrt1a and Dmrt1b, caused by an alternative splicing. The Dmrt1b has an insertion of three nucleotides (CAG) in the open reading frame. Figla and Dmrt1 displayed gonadal-specific expression and abundant in the ovaries and in the testes, respectively. In particular, levels of Figla expression in the ovaries were higher in the spawning season than in the non-spawning season. Once sex change began, Figla mRNA decreased and Dmrt1 mRNA increased with progression of oocyte degeneration and spermatogenesis. These expression levels were maintained until the completion of the sex change. Low Figla and high Dmrt1 were also observed in testes of primary males, which functioned as a gonochoristic male throughout its life span in this wrasse. The results of this study suggest that these genes may regulate the gonadal transition from ovary to testis by the same mechanism as that of formation and maintenance of the primary testis in H. poecilopterus. PMID:23030342

Miyake, Yuko; Sakai, Yoichi; Kuniyoshi, Hisato

2012-10-01

345

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

PubMed

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

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

2014-01-01

346

Transcription factor E2-2 is an essential and specific regulator of plasmacytoid dendritic cell development  

PubMed Central

Summary Plasmacytoid dendritic cells (PDC) represent a unique immune cell type specialized in type I interferon (IFN) secretion in response to viral nucleic acids. The molecular control of PDC lineage specification has been poorly understood. We report that basic helix-loop-helix transcription factor (E protein) E2-2/Tcf4 is preferentially expressed in murine and human PDC. Constitutive or inducible deletion of murine E2-2 blocked the development of PDC but not of other lineages, and abolished IFN response to unmethylated DNA. Moreover, E2-2 haploinsufficiency in mice and in human Pitt-Hopkins syndrome patients was associated with aberrant expression profile and impaired IFN response of the PDC. E2-2 directly activated multiple PDC-enriched genes, including transcription factors involved in PDC development (SpiB, Irf8) and function (Irf7). These results identify E2-2 as a specific transcriptional regulator of the PDC lineage in mice and humans, and reveal a key function of E proteins in the innate immune system. PMID:18854153

Cisse, Babacar; Caton, Michele L.; Lehner, Manfred; Maeda, Takahiro; Scheu, Stefanie; Locksley, Richard; Holmberg, Dan; Zweier, Christiane; den Hollander, Nicolette S.; Kant, Sarina G.; Holter, Wolfgang; Rauch, Anita; Zhuang, Yuan; Reizis, Boris

2008-01-01

347

Regulation of the Arabidopsis root vascular initial population by LONESOME HIGHWAY.  

PubMed

Complex organisms consist of a multitude of cell types arranged in a precise spatial relation to each other. Arabidopsis roots generally exhibit radial tissue organization; however, within a tissue layer, cells are not identical. Specific vascular cell types are arranged in diametrically opposed longitudinal files that maximize the distance between them and create a bilaterally symmetric (diarch) root. Mutations in the LONESOME HIGHWAY (LHW) gene eliminate bilateral symmetry and reduce the number of cells in the center of the root, resulting in roots with only single xylem and phloem poles. LHW does not appear to be required for the creation of any specific cell type, but coordinately controls the number of all vascular cell types by regulating the size of the pool of cells from which they arise. We cloned LHW and found that it encodes a protein with weak sequence similarity to basic helix-loop-helix (bHLH)-domain proteins. LHW is a transcriptional activator in vitro. In plants, LHW is nuclear-localized and is expressed in the root meristems, where we hypothesize it acts independently of other known root-patterning genes to promote the production of stele cells, but might also indirectly feed into established regulatory networks for the maintenance of the root meristem. PMID:17626058

Ohashi-Ito, Kyoko; Bergmann, Dominique C

2007-08-01

348

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

PubMed Central

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

Jagle, Sabine; Ronsch, Kerstin; Timme, Sylvia; Andrlova, Hana; Bertrand, Miriam; Jager, Marcel; Proske, Amelie; Schrempp, Monika; Yousaf, Afsheen; Michoel, Tom; Zeiser, Robert; Werner, Martin; Lassmann, Silke; Hecht, Andreas

2014-01-01

349

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

PubMed

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

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

2014-04-01

350

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

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

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

2013-01-01

351

Myor/ABF-1 Mrna Expression Marks Follicular Helper T Cells but Is Dispensable for Tfh Cell Differentiation and Function In Vivo  

PubMed Central

Follicular T helper cells (Tfh) are crucial for effective antibody responses and long term T cell-dependent humoral immunity. Although many studies are devoted to this novel T helper cell population, the molecular mechanisms governing Tfh cell differentiation have yet to be characterized. MyoR/ABF-1 is a basic helix-loop-helix transcription factor that plays a role in the differentiation of the skeletal muscle and Hodgkin lymphoma. Here we show that MyoR mRNA is progressively induced during the course of Tfh-like cell differentiation in vitro and is expressed in Tfh responding to Alum-precipitated antigens in vivo. This expression pattern suggests that MyoR could play a role in the differentiation and/or function of Tfh cells. We tested this hypothesis using MyoR-deficient mice and found this deficiency had no impact on Tfh differentiation. Hence, MyoR-deficient mice developed optimal T-dependent humoral responses to Alum-precipitated antigens. In conclusion, MyoR is a transcription factor selectively up-regulated in CD4 T cells during Tfh cell differentiation in vitro and upon response to alum-protein vaccines in vivo, but the functional significance of this up-regulation remains uncertain. PMID:24386375

Debuisson, Delphine; Mari, Nathalie; Denanglaire, Sebastien

2013-01-01

352

Hypoxia-inducible factor signaling in the development of kidney fibrosis  

PubMed Central

A discrepancy between oxygen availability and demand has been found in most chronic kidney diseases (CKD) irrespective of etiology. This results from a combination of structural and functional changes that are commonly associated with the development of fibrosis, which include a reduction in peritubular blood flow, luminal narrowing of atherosclerotic vessels, capillary rarefaction and vascular constriction due to altered expression of vasoactive factors and signaling molecules (e.g. angiotensin II, endothelin, nitric oxide). Consistent with decreased renal oxygenation in CKD is the increased expression of the oxygen-sensitive ?-subunit of hypoxia-inducible factor (HIF)-1. HIF transcription factors are members of the Per-ARNT-Sim (PAS) family of heterodimeric basic helix-loop-helix transcription factors and consist of an oxygen-sensitive ?-subunit and a constitutively expressed ?-unit, also known as the aryl-hydrocarbon-receptor nuclear translocator (ARNT) or HIF-?. Recent experimental evidence suggests that prolonged activation of HIF signaling in renal epithelial cells enhances maladaptive responses, which lead to fibrosis and further tissue destruction. Cell type-specific functions of individual HIF transcription factors and their relevant transcriptional targets are discussed in the context of renal fibrogenesis. PMID:23259746

2012-01-01

353

Phosphorylation-Coupled Proteolysis of the Transcription Factor MYC2 Is Important for Jasmonate-Signaled Plant Immunity  

PubMed Central

As a master regulator of jasmonic acid (JA)–signaled plant immune responses, the basic helix-loop-helix (bHLH) Leu zipper transcription factor MYC2 differentially regulates different subsets of JA–responsive genes through distinct mechanisms. However, how MYC2 itself is regulated at the protein level remains unknown. Here, we show that proteolysis of MYC2 plays a positive role in regulating the transcription of its target genes. We discovered a 12-amino-acid element in the transcription activation domain (TAD) of MYC2 that is required for both the proteolysis and the transcriptional activity of MYC2. Interestingly, MYC2 phosphorylation at residue Thr328, which facilitates its turnover, is also required for the MYC2 function to regulate gene transcription. Together, these results reveal that phosphorylation-coupled turnover of MYC2 stimulates its transcription activity. Our results exemplify that, as with animals, plants employ an “activation by destruction” mechanism to fine-tune their transcriptome to adapt to their ever-changing environment. PMID:23593022

Zhai, Qingzhe; Yan, Liuhua; Tan, Dan; Chen, Rong; Sun, Jiaqiang; Gao, Liyan; Dong, Meng-Qiu; Wang, Yingchun; Li, Chuanyou

2013-01-01

354

Up-regulation of the Sirtuin 1 (Sirt1) and Peroxisome Proliferator-activated Receptor ? Coactivator-1? (PGC-1?) Genes in White Adipose Tissue of Id1 Protein-deficient Mice: IMPLICATIONS IN THE PROTECTION AGAINST DIET AND AGE-INDUCED GLUCOSE INTOLERANCE.  

PubMed

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

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

2014-10-17

355

Nemo promotes Notch-mediated lateral inhibition downstream of proneural factors.  

PubMed

During neurogenesis, conserved tissue-specific proneural factors establish a cell's competence to take on neural fate from within a field of unspecified cells. Proneural genes encode basic helix-loop-helix transcription factors that promote the expression of 'core' and subtype-specific target genes. Target genes include both pan-neuronal genes and genes that aid in the process of refinement, known as lateral inhibition. In this process, proneural gene expression is increased in the neural progenitor while simultaneously down-regulated in the surrounding cells, in a Notch signalling-dependent manner. Here, we identify nemo (nmo) as a target of members of both Drosophila Atonal and Achaete-Scute proneural factor families and find that mammalian proneural homologs induce Nemo-like-kinase (Nlk) expression in cell culture. We find that nmo loss of function leads to reduced expression of Notch targets and to perturbations in Notch-mediated lateral inhibition. Furthermore, Notch hyperactivity can compensate for nmo loss in the Drosophila eye. Thus nmo promotes Notch-mediated lateral inhibition downstream of proneural factors during neurogenesis. PMID:24880113

Fernandes, Vilaiwan M; Panchapakesan, Shanker S S; Braid, Lorena R; Verheyen, Esther M

2014-08-15

356

Overexpression of the m4 and malpha genes of the E(spl)-complex antagonizes notch mediated lateral inhibition.  

PubMed

Intercellular signalling mediated by Notch proteins is crucial to many cell fate decisions in metazoans. Its profound effects on cell fate and proliferation require that a complex set of responses involving positive and negative signal transducers be orchestrated around each instance of signalling. In Drosophila the basic-helix-loop-helix (bHLH) repressor encoding genes of the E(spl) locus are induced by Notch signalling and mediate some of its effects, such as suppression of neural fate. Here we report on a novel family of Notch responsive genes, whose products appear to act as antagonists of the Notch signal in the process of adult sensory organ precursor singularization. They, too, reside in the E(spl) locus and comprise transcription units E(spl) m4 and E(spl) malpha. Overexpression of these genes causes downregulation of E(spl) bHLH expression accompanied by cell autonomous overcommitment of sensory organ precursors and tufting of bristles. Interestingly, negative regulation of the Notch pathway by overexpression of E(spl) m4 and malpha is specific to the process of sensory organ precursor singularization and does not impinge on other instances of Notch signalling. PMID:10446264

Apidianakis, Y; Nagel, A C; Chalkiadaki, A; Preiss, A; Delidakis, C

1999-08-01

357

Basic lubrication equations  

NASA Technical Reports Server (NTRS)

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.

Hamrock, B. J.; Dowson, D.

1981-01-01

358

Basics of Cell Culture  

NSDL National Science Digital Library

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

Afshar, Golnar

2012-03-12

359

Basic plasma physics II  

Microsoft Academic Search

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

A. A. Galeev; R. N. Sudan

1984-01-01

360

Basic Liquid Chromatography  

NSDL National Science Digital Library

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

Kazakevich, Yuri.; McNair, Harold Monroe, 1933-.

1996-01-01

361

Basics of Endocrine Function  

NSDL National Science Digital Library

This flash video presentation provides an introduction to the basics of the endocrine system. It defines the criteria for determining if a chemical is a hormone and compares the action of hormones with other signalling chemicals and with the way the nervous system functions. The last part of the presentation gives a preview of a flowchart homework activity that can be used by students as a way to learn the function of specific hormones.

Dr. Daniel Brouse (Human Anatomy and Physiology Society)

2008-08-09

362

Superbug Survival is Basic  

NSDL National Science Digital Library

This on-line news article investigates the question: Can microbial life thrive in the caustic conditions common to floor strippers and baking soda? It reports samples near a landfill in south Chicago that reveal alkaline solutions are basic to certain bacterial superbugs. The article explores the habitat, genetic analysis, and close relatives of these microbial wonders while also conveying that much more research is needed in the area. Useful links are located at the end of the article.

Matsos, Helen; Magazine, Nasa A.

363

Basics of Space Flight  

NSDL National Science Digital Library

This training module was designed to help the user identify and grasp basic concepts associated with space travel and deep space missions. Separate sections deal with topics such as the physical environment of space (solar system, gravity, orbital mechanics), flight projects (mission concepts, system requirements, design, onboard systems and instruments), and flight operations (launch, cruise, encounter). Links to related topics are embedded in the text.

364

Superbug Survival is Basic  

NSDL National Science Digital Library

This on-line news article investigates the question: Can microbial life thrive in the caustic conditions common to floor strippers and baking soda? It reports samples near a landfill in south Chicago that reveal alkaline solutions are basic to certain bacterial superbugs. The article explores the habitat, genetic analysis, and close relatives of these microbial wonders while also conveying that much more research is needed in the area. Useful links are located at the end of the article.

Matsos, Helen

2010-05-06

365

Basics of Biosafety  

NASA Technical Reports Server (NTRS)

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.

Wong, Willy

2009-01-01

366

Population: Basic Statistics  

NSDL National Science Digital Library

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

Rhinehart, Ken; Pratte, John

367

Synergistic interactions of lipids and myelin basic protein  

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

368

The Basic Anaesthesia Machine  

PubMed Central

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

Gurudatt, CL

2013-01-01

369

Wimba Voice Design Basics Worksheet  

E-print Network

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

Xu, Shouhuai

370

Basic Hitchhiker Payload Requirements  

NASA Technical Reports Server (NTRS)

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

Horan, Stephen

1999-01-01

371

Transmission Electron Microscopy Basics  

NSDL National Science Digital Library

This extensive site from the University of Liverpool is a set of resources based on the textbook Transmission Electron Microscopy - Basics by D.B.Williams and C.B.Carter. The tutorial is designed to accompany an introductory course on transmission electron microscopy for students with an understanding of elementary physics. Topics include electron scattering, electron atom interactions, the electron gun, probe size, lenses, depth of field and depth of focus, and others. Each chapter includes interactive Java applets that facilitate understanding of the concepts presented.

Goodhew, Peter; Matter.org

372

Basic Financial Statements  

NSDL National Science Digital Library

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

Garrison, Sharon H.

2007-05-23

373

Basic and clinical immunology  

NASA Technical Reports Server (NTRS)

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

Chinen, Javier; Shearer, William T.

2003-01-01

374

Basics of NMR  

NSDL National Science Digital Library

Dr. Joseph Hornak of the Rochester Institute of Technology presents this high quality hypertextbook for in-depth coverage of the physics and technique behind Nuclear Magnetic Resonance (NMR) (For Dr. Hornak's Basics of MRI, see the August 4, 1999 Scout Report for Science & Engineering). The material is presented in a detailed and clear manner without over simplifying the concepts. Chapters include "The Mathematics of NMR," "Spin Physics," "NMR Spectroscopy," "Fourier Transforms," "Pulse Sequences," and much more. A chapter on "NMR Hardware" offers an overview of components (like the superconducting magnet and various coils) used in most NMR systems. The "Practical Considerations" chapter emphasizes spectroscopic techniques. With the screen split into two separate frames, explanatory graphics can be viewed alongside the text. A glossary and a list of symbols are also included in this carefully produced textbook.

Hornak, Joseph P.

2005-10-31

375

Basic and Clinical Neurosciences  

NSDL National Science Digital Library

Columbia University's College of Physicians and Surgeons has been a leader in medical education for over a century, and this website is provided as public service for those in the field of medicine and neuroscience. The website provides a series of lectures and videos that provide a "comprehensive and concise review of the neurosciences." It's best to start by reading the executive summary, and then click on over to the "Topics and Speakers" area. Here visitors can look over several dozen lectures that include "Basic Mechanisms of Pain", "Molecular Genetics", and "Neurobiology of Schizophrenia". The lectures are all of very high quality, and visitors who are seeking additional information should look through the "References and Resources" area for external links to relevant medical organizations, research institutes, and academic departments.

376

Fluid Power Basics  

NSDL National Science Digital Library

Students learn about the fundamental concepts important to fluid power, which includes both pneumatic (gas) and hydraulic (liquid) systems. Both systems contain four basic components: reservoir/receiver, pump/compressor, valve, cylinder. Students learn background information about fluid powerâboth pneumatic and hydraulic systemsâincluding everyday applications in our world (bulldozers, front-end loaders, excavators, chair height lever adjustors, door closer dampers, dental drills, vehicle brakes) and related natural laws. After a few simple teacher demos, they learn about the four components in all fluid power systems, watch two 26-minute online videos about fluid power, complete a crossword puzzle of fluid power terms, and conduct a task card exercise. This prepares them to conduct the associated hands-on activity, using the Portable Fluid Power Demonstrator (teacher-prepared kits) to learn more about the properties of gases and liquids in addition to how forces are transmitted and multiplied within these systems.

Center for Compact and Efficient Fluid Power, College of Agriculture and Biological Engineering,

377

Basics of Electricity  

NSDL National Science Digital Library

This course is one of the quickStep series offered by Siemens in Electricity. These are FREE on-line industrial knowledge building tutorials. quickSTEPs are a great start for industry novices moving into technical jobs or staff in operational support rolls. They can also be very effectively used as out of class assignments for review or to build fundamental skills. Each course includes: an online tutorial organized as a number of units, lessons with self check quiz questions, a glossary of terms, a self-check final exam with scoring, an extensive downloadable PDF, and a study guide. This course focuses on the basics of electricity. The coverage includes: DC circuits, magnetism, alternating current, reactance, impedance, AC circuits and an 88 page study guide.

2008-11-10

378

Basic AC Theory  

NSDL National Science Digital Library

reated by Tony R. Kuphaldt with help from Harvey Lew, Duane Damiano, Mark D. Zarella, John Symonds, and Jason Starck, this chapter of All About Circuit's second volume on Alternating Current describes the basic theory and principles at work. The chapter is divided into six sections: What is alternating current?, AC waveforms, Measurements of AC magnitude, Simple AC circuit calculations, AC phase, and Principles of radio. Each section has clear illustrations and a concise, bulleted review of what was covered at the end. There is also a link to the All About Circuits forums, where contributors and other visitors discuss the material presented. This is an excellent resource for educators in physics and electronic engineering classrooms to introduce lessons or units on alternating current.

Kuphaldt, Tony R.

2008-07-15

379

[Pediatric basic life support].  

PubMed

The new international consensus and guidelines were published by American Heart Association in October 2010. These guidelines include many important changes in pediatric basic life support(BLS) based on many evidences. Especially in children, asphyxial cardiac arrest has been more common than cardiac arrest and only one third to one half victims can receive bystander cardiopulmonary resuscitation(CPR). According to new guidelines, "CAB" (Chest compressions/Circulation, Airway, and Breathing/ventilation) is recommended instead of "ABC" sequence. In addition, pediatric chain of survival is revised and the section of "Look, Listen, Feel" is deleted. These changes are recommended in order to simplify training with the hope that more pediatric victims will consequently receive bystander CPR. PMID:21591413

Morita, Kouji

2011-04-01

380

Basic Concepts of Electricity  

NSDL National Science Digital Library

All About Circuits is a website that âÂÂprovides a series of online textbooks covering electricity and electronics.â Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This particular section, Basic Concepts of Electricity, is the first chapter in Volume I. Topics covered in this chapter include: static electricity, conductors, insulators, electron flow, electric circuits, voltage, current, and resistance. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

2008-07-04

381

Basic Accounting Lesson Plans  

NSDL National Science Digital Library

Are balance sheets, income statements and cash flow statements keeping you up at night? Well, beginning accounting students (or others with an interest in such matters) will appreciate these basic accounting lesson plans, provided courtesy of the MoneyInstructors.com website. The first section contains a number of lesson plans and worksheets that include topics such as the fundamental concepts of accounting, transaction analysis, accrual accounting and adjusting entries. Moving on, the site also contains a number of useful articles on various topics within the field, such as bookkeeping, ledgers, and profit and loss reports. The site is rounded out by a selection of helpful accounting textbooks that students may wish to look for as they continue their journey through the world of accounting.

382

Corrosion: Understanding the basics  

SciTech Connect

This new book presents a practical how to approach to understanding and solving the problems of corrosion of structural materials. Although it is written mainly for those having a limited technical background in corrosion, it also provides more experienced engineers with a useful overview of the principles of corrosion and can be used as a general guide for developing a corrosion-control program. Contents include: the effects and economic impact of corrosion; basic concepts important to corrosion; principles of aqueous corrosion; forms of corrosion: recognition and prevention; types of corrosive environments; corrosion characteristics of structural materials; corrosion control by proper design; corrosion control by materials selection; corrosion control by protective coatings and inhibitors; corrosion control by cathodic and anodic protection; corrosion testing and monitoring; techniques for diagnosis of corrosion failures; and glossary of corrosion-related terms.

Davis, J.R. [ed.

2000-07-01

383

Basic Nanotechnology Processes Laboratory  

NSDL National Science Digital Library

This laboratory course is provided by Nano4Me.org, a product of the National Center for Nanotechnology Applications and Career Knowledge (NACK Center) which is based at the Penn State College of Engineering and is funded through the National Science Foundation's Advanced Technological Education (ATE) program. These twelve labs focus on basic processes in Nanotechnology. Some of the labs are titled Gold Nucleation Analysis, Introduction to LPCVD and PECVD, Introduction to Plasma-based Processing, Liftoff and Surface Modification, and Intro to Scanning Electron Microscopy. These labs can be used in conjunction in a course, or individually as needed by the teacher. Each lab should include an objective, background information, detailed procedure, charts and tables, and follow-up questions. This resource, along with all resources from the NACK Center, require a fast, easy, free log-in to access their materials.

2011-03-08

384

Basic Business Statistics  

NSDL National Science Digital Library

As business is one of the most popular undergraduate majors in the United States, it stands to reason that there are a number of specialized textbooks and supporting instructional materials that are dedicated to various topics within this field. This particular website is designed to serve as the companion to a basic business statistic textbook published by Prentice Hall, and it contains quizzes, overviews, and other materials that will be helpful to both students of the discipline and educators. The materials here are divided into nineteen chapters that cover topics like sampling, data presentation, linear regression, and decision making. Visitors can also take advantage of the search engine here, which is located at the top right-hand corner of each page.

Berenson, Mark L.; Krehbiel, Timothy C.; Levine, David M., 1946-

2009-06-12

385

Basics of Electrical Products  

NSDL National Science Digital Library

This course is one of the quickStep series offered by Siemens in Electrical Products. These are FREE on-line industrial knowledge building tutorials. quickSTEPs are a great start for industry novices moving into technical jobs or staff in operational support rolls. They can also be very effectively used as out of class assignments for review or to build fundamental skills. Each course includes: -an online tutorial organized as a number of units and lessons with self check quiz questions-a glossary of terms-a self-check final exam with scoring -an extensive downloadable pdf study guideThis course on the basics of electrical products covers residential, commerical, and industrial applications.

2009-06-12

386

Basics of Circuit Breakers  

NSDL National Science Digital Library

This course is one of the quickStep series offered by Siemens in Circuit Breakers. These are FREE on-line industrial knowledge building tutorials. quickSTEPs are a great start for industry novices moving into technical jobs or staff in operational support rolls. They can also be very effectively used as out of class assignments for review or to build fundamental skills. Each course includes: an online tutorial organized as a number of units, lessons with self check quiz questions, a glossary of terms, a self-check final exam with scoring, an extensive downloadable PDF study guide. This course offers: basic concepts, breakers part one, breakers part two, a final exam, a glossary and an 88 page study guide.

2008-11-06

387

Basics of AC Motors  

NSDL National Science Digital Library

This course is one of the quickStep series offered by Siemens in AC Motors. These are FREE on-line industrial knowledge building tutorials. quickSTEPs are a great start for industry novices moving into technical jobs or staff in operational support rolls. They can also be very effectively used as out of class assignments for review or to build fundamental skills. Each course includes: an online tutorial organized as a number of units, lessons with self check quiz questions, a glossary of terms, a self-check final exam with scoring, an extensive downloadable PDF study guide. This course covers: motor basics, NEMA motors, Siemens motorr, final exam, a glossary, plus a 116 page study guide.

2008-11-26

388

Quality Standards for Basic Skills.  

ERIC Educational Resources Information Center

The Adult Literacy and Basic Skills Unit (ALBSU) is committed to improving the quality of basic skills provision in England and Wales. It has encouraged the development of quality assurance in basic skills so that potential and existing students know what they should be entitled to expect. ALBSU's Good Practice documents published since 1984 have…

Adult Literacy and Basic Skills Unit, London (England).

389

Basics of cytology  

PubMed Central

This overview is intended to give a general outline about the basics of Cytopathology. This is a field that is gaining tremendous momentum all over the world due to its speed, accuracy and cost effectiveness. This review will include a brief description about the history of cytology from its inception followed by recent developments. Discussion about the different types of specimens, whether exfoliative or aspiration will be presented with explanation of its rule as a screening and diagnostic test. A brief description of the indications, utilization, sensitivity, specificity, cost effectiveness, speed and accuracy will be carried out. The role that cytopathology plays in early detection of cancer will be emphasized. The ability to provide all types of ancillary studies necessary to make specific diagnosis that will dictate treatment protocols will be demonstrated. A brief description of the general rules of cytomorphology differentiating benign from malignant will be presented. Emphasis on communication between clinicians and pathologist will be underscored. The limitations and potential problems in the form of false positive and false negative will be briefly discussed. Few representative examples will be shown. A brief description of the different techniques in performing fine needle aspirations will be presented. General recommendation for the safest methods and hints to enhance the sensitivity of different sample procurement will be given. It is hoped that this review will benefit all practicing clinicians that may face certain diagnostic challenges requiring the use of cytological material. PMID:23210005

Al-Abbadi, Mousa A.

2011-01-01

390

Basic concepts of epigenetics  

PubMed Central

Through epigenetic modifications, specific long-term phenotypic consequences can arise from environmental influence on slowly evolving genomic DNA. Heritable epigenetic information regulates nucleosomal arrangement around DNA and determines patterns of gene silencing or active transcription. One of the greatest challenges in the study of epigenetics as it relates to disease is the enormous diversity of proteins, histone modifications and DNA methylation patterns associated with each unique maladaptive phenotype. This is further complicated by a limitless combination of environmental cues that could alter the epigenome of specific cell types, tissues, organs and systems. In addition, complexities arise from the interpretation of studies describing analogous but not identical processes in flies, plants, worms, yeast, ciliated protozoans, tumor cells and mammals. This review integrates fundamental basic concepts of epigenetics with specific focus on how the epigenetic machinery interacts and operates in continuity to silence or activate gene expression. Topics covered include the connection between DNA methylation, methyl-CpG-binding proteins, transcriptional repression complexes, histone residues, histone modifications that mediate gene repression or relaxation, histone core variant stability, H1 histone linker flexibility, FACT complex, nucleosomal remodeling complexes, HP1 and nuclear lamins. PMID:22395460

Mazzio, Elizabeth A

2012-01-01

391

Network basics for telemedicine.  

PubMed

Early telemedicine networks employed dedicated telecommunications circuits (e.g. leased digital lines) in which the sender and receiver were connected by a private circuit. More recently, the Internet has become widely available for general use, including telemedicine. The Internet was engineered to permit network paths to be shared by all users, so data transmission is fundamentally different from traditional, circuit-switched networks. Early telemedicine applications demonstrated the feasibility of Internet Protocol transmission. The basic performance criteria to use in evaluating newer digital communications technologies that carry both voice and data are: (1) bandwidth; (2) packet loss; (3) end-to-end delay; (4) jitter; (5) privacy and security. Network engineering involves performance trade-offs between the hardware, architecture, security and the budget available. A telemedicine application may be running over a network whose design is entirely under the user's control, or the application may employ some part of the Internet whose design is unknown to the user. If an application is not running to satisfaction, then a network engineer should be consulted. PMID:15829050

Gemmill, Jill

2005-01-01

392

Seizures in Adults (Beyond the Basics)  

MedlinePLUS

... malformations in the brain (The Basics) Patient information: Brain cancer (The Basics) Patient information: Brain metastases (The Basics) ... materials. Patient information: Seizures (The Basics) Patient information: Brain cancer (The Basics) Patient information: Head injury in children ...

393

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 ...

394

PEROXISOME PROLIFERATOR-ACTIVATED RECEPTORa (PPARa) 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,...

395

NMR-assignments of a cytosolic domain of the C-terminus of polycystin-2  

E-print Network

+Business Media B.V. 2009 Abstract Mutations in the PKD2 gene lead to the development of polycystic kidney disease with the existence of two paired helix-loop-helix (HLH) motifs. Keywords Polycystin-2 Á PKD2 Á Polycystic kidney-dominant poly- cystic kidney disease (Mochizuki et al. 1996). According to structural predictions, polycystin-2

Witzgall, Ralph - Naturwissenschaftliche Fakultät III

396

2008LANDESBIOSCIENCE.DONOTDISTRIBUTE. 28 Cell Cycle 2008; Vol. 7 Issue 1  

E-print Network

element in all living organisms and is required as a cofactor for oxygen-binding proteins. Iron metabolism consists of two helix-loop-helix proteins: a regulatory subunit, HIF-1a, which is the oxygen by the tumor suppressor protein vHL through a process that requires molecular iron. The PHDs represent an i

Nizet, Victor

397

Functionally distinct isoforms of the CRE-BP DNA-binding protein mediate activity of a T-cell-specific enhancer.  

PubMed Central

Expression of the CD3 delta gene of the T-cell receptor (TCR) complex is regulated by a T-cell-specific enhancer. A highly conserved 40-bp motif (element delta A) within the CD3 delta enhancer is responsible for mediating its activity and specificity. Element delta A exhibits sequence similarities to the cyclic AMP response element (CRE) but does not respond to changes in the level of cyclic AMP. Using the delta A element as a probe, we have isolated three cDNA clones encoding three distinct protein isoforms, products of differential splicing and alternate promoter usage of the CRE-BP gene. These isoforms share the DNA binding and dimerization domains at the C terminus of the protein but differ at their N termini. In transfection assays, their activities as transcription regulators differ: CRE-BP2 is a potent activator, CRE-BP3 is a weak activator, and CRE-BP1 is transcriptionally inert. Mutations in the basic region of the CRE-BP1 protein which abrogate its ability to bind DNA render this protein a dominant repressor of the delta A enhancer. Antibodies to the CRE-BP protein interact specifically with the ubiquitous and predominantly T-cell-restricted nuclear complexes that bind to the delta A element and suggest the presence of this protein in homo- and heterodimeric complexes. Since the delta A motif is also present in the enhancer and promoter of the TCR alpha and beta genes, the CRE-BP isoforms may mediate expression of other members of the CD3/TCR complex during T-cell development. Images PMID:1531087

Georgopoulos, K; Morgan, B A; Moore, D D

1992-01-01

398

Online Basic Courses for Energy and Automation  

NSDL National Science Digital Library

Free on-line industrial knowledge building tutorials. quickSTEPs are a great start for industry novices moving into technical jobs or staff in operational support rolls. These are pretty basic courses but could be a good out of classroom review activity. Each Basic course has some self check quiz questions. Each course comes with a pdf manual and reference guide.The topics include: introductory courses basics of electricity; basics of electrical products; motors & control courses; basics of AC drives; basics of AC motors; basics of control components; basics of DC drives; basics of motor control centers; basics of PLCs; basics of sensors; power distribution courses; basics of busway; basics of circuit breakers; basics of load centers; basics of panel boards; basics of power monitoring; basics of safety switches; basics of surge protection. Admittedly this is a site for Siemens personnel and sales staff to get on line training for Siemens products but it genuinely has some good fundamental information.

2009-06-30

399

Creating Adult Basic Education Programs.  

ERIC Educational Resources Information Center

Adult basic education programs must teach the "social living skills" disadvantaged adults need, as well as basic literacy skills. In creating an ABE program, one must first assess the needs of the target population--through surveys, group meetings, an advisory council of members of the target population, demographic studies, and consideration of…

Harris, Dolores M.

400

Basic Skills: Dealing with Deficiencies.  

ERIC Educational Resources Information Center

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…

New Mexico State Univ., Las Cruces.

401

Basic Research and International Spillovers  

Microsoft Academic Search

This paper discriminates between basic and developmental research when estimating international research spillovers between nine OECD nations. Using panel cointegration techniques, the estimates show that basic research generates much larger international spillovers than developmental research. Developmental research in turn appears more easily appropriated by the research performer, and thus has a stronger effect domestically. These results suggest growth models should

Mark Funk

2002-01-01

402

Children and Their Basic Needs.  

ERIC Educational Resources Information Center

Describes obstacles presented by poverty in the fulfillment of the basic needs of children. Individually addresses Maslow's five basic needs with regard to children reared in poverty: (1) physiological needs; (2) safety needs; (3) belonging and love needs; (4) self-esteem needs; and (5) self-actualization needs. (Author/SD)

Prince, Debra Lindsey; Howard, Esther M.

2002-01-01

403

What basic–applied issue?  

Microsoft Academic Search

Human Factors (HF) is the scientific discipline concerned with the interactions among humans and built systems. HF psychologists are often involved in a supposed tug-of-war between the basic and applied scientific research communities. We suggest, however, that there really is no meaningful distinction between basic and applied science. We provide historical examples, medieval, modern and contemporary, demonstrating that a fundamental

William S. Helton; Simon Kemp

2011-01-01

404

BASIC Instructional Program: System Documentation.  

ERIC Educational Resources Information Center

This report documents the BASIC Instructional Program (BIP), a "hands-on laboratory" that teaches elementary programming in the BASIC language, as implemented in the MAINSAIL language, a machine-independent revision of SAIL which should facilitate implementation of BIP on other computing systems. Eight instructional modules which make up the BIP…

Dageforde, Mary L.

405

Basic Education in International Perspective.  

ERIC Educational Resources Information Center

These papers, delivered at the 1981 World Assembly of the International Council on Education for Teaching, reflect the theme of the conference: provision of basic education for all persons, focusing particularly on policies and situations in developing nations. The 14 presentations were from nine nations: (1) "Curriculum Materials for Basic…

Cain, Edmund J.; And Others

406

JAMA Patient Page: Basic Science Research  

MedlinePLUS

... of Health and Human Services VALUE OF BASIC SCIENCE RESEARCH Basic science research can help in a ... dedicated to basic science and translational research. Basic Science Research JAMA PATIENT PAGE The JAMA Patient Page ...

407

Introduction to Basic GIS Skills  

NSDL National Science Digital Library

Chad Heinzel, University of Northern Iowa Summary Develops basic GIS skills, directs students to other shapefiles (on-campus and off), sets the stage for adding additional class/campus data later in the semester. ...

Heinzel, Chad

408

Basics of Pediatric SCI Rehabilitation  

MedlinePLUS Videos and Cool Tools

... The Basics of Pediatric SCI Rehabilitation Transitions for Children with Spinal Cord Injury How many spinal cord ... the major cause of spinal cord injuries to children? What role do car seats play in pediatric ...

409

Basic Exchangeable Cations in Soils.  

National Technical Information Service (NTIS)

Several possible solutions for displacing basic exchangeable cations have been tested on some agricultural soils. The quantities of cations which the solutions could displace varied according to the nature of the displacing ion. This behaviour is comparab...

B. M. Tucker

1971-01-01

410

Basic Education Reform in China.  

ERIC Educational Resources Information Center

Examines the general process and outcomes of basic education reform in the context of changes in the educational system of China. Identifies lessons the Chinese reform experience can offer other developing countries. (SLD)

Wang, Chengzhi; Zhou, Quanhua

2002-01-01

411

Diabetic Neuropathy (Beyond the Basics)  

MedlinePLUS

... diabetes mellitus Type 2 diabetes mellitus Patient information: Diabetic neuropathy (Beyond the Basics) Author Eva L Feldman, MD, ... MD, PhD Find Print Contents of this article DIABETIC NEUROPATHY OVERVIEW DIABETIC NEUROPATHY RISK FACTORS DIABETIC NEUROPATHY SYMPTOMS ...

412

Low-Frequency Radioastronomy Basics  

NASA Astrophysics Data System (ADS)

With the many large instruments in construction or in project, the present epoch corresponds to a renewal of low-frequency radioastronomy. The field will attract new researchers and students not expert of the radioastronomy techniques. With this audience in mind, we present here a very brief introduction to radioastronomy basics, including propagation and polarization of low-frequency radio waves as well as instrumental aspects. Basic formulas are given. The references and internet links will allow the interested reader to go further.

Zarka, P.

2011-04-01

413

A Basic Introduction to Ecology  

NSDL National Science Digital Library

Ecology is the science that studies the interactions and relationships that exist among living organisms with each other and their environment. This selection offers tools necessary to define ecology, while gaining a better understanding of its application to real world experiences. It offers instruction in basic ecological terms, while explaining the meaning of the biotic and abiotic factors within an environment and presents examples of those influences. You will also find information necessary to identify the basic factors necessary for living.

Galle, Janet R.; Warren, Patricia A.

2005-01-01

414

Basic research for environmental restoration  

SciTech Connect

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.

Not Available

1990-12-01

415

The Basicity of Texas Soils.  

E-print Network

at the final points. most of the soils selected were low in bu$er ca,pacitp, the beginning poir was acid equivalent to 200 parts per million of sulphur in the soil. for IUC- the As Method: Weigh 8 grams of the soil into a 150 cc. beaker and add 1 cc... basicity, in terms of calcium car- bonate equivalent to the acid consumed. An acid consumed of 10 per cent is equivalent to a basicity of 1.0 per cent of the soil; that is, the bases which neutralize the acid under the conditisns of the test, would 16...

Fraps, G. S. (George Stronach); Carlyle, E. C. (Elmer Cardinal)

1929-01-01

416

Cosmic Particle Acceleration: Basic Issues  

E-print Network

Cosmic-rays are ubiquitous, but their origins are surprisingly difficult to understand. A review is presented of some of the basic issues common to cosmic particle accelerators and arguments leading to the likely importance of diffusive shock acceleration as a general explanation. The basic theory of diffusive shock acceleration is outlined, followed by a discussion of some of the key issues that still prevent us from a full understanding of its outcomes. Some recent insights are mentioned at the end that may help direct ultimate resolution of our uncertainties.

T. W. Jones

2000-12-22

417

NANOMATERIALS FOR PROTEIN MEDIATED THERAPY AND DELIVERY  

PubMed Central

There has been a significant amount of research done on liposomes and nanoparticles as drug carriers for protein drugs. Proteins and enzymes have been used both as targeting moieties and for their therapeutic potential. High specificity and rapid reaction rates make proteins and enzymes excellent candidates for therapeutic treatment, but some limitations exist. Many of these limitations can be addressed by a well studied nanotechnology based delivery system. Such a system can provide a medium for delivery, stabilization of the drugs, and enable site specific accumulation of drugs. Nanomedicines such as these have great potential to revolutionize the pharmaceutical industry and improve healthcare worldwide.

Barry, John N.; Vertegel, Alexey A.

2014-01-01

418

Metamorphic proteins mediate evolutionary transitions of structure  

E-print Network

diversity lectins oligomerization protein evolution Maynard-Smith's conjecture of protein evolution structure into a new one should therefore (or must, by default, if one follows Maynard-Smith's conjecture

Tawfik, Dan S.

419

Basic Scientific Subroutines, Volume II.  

ERIC Educational Resources Information Center

This book, second in a series dealing with scientific programing in the BASIC language, provides students, engineers, and scientists with a documented library of subroutines for scientific applications. Subjects of the eight chapters include: (1) least-squares approximation of functions and smoothing of data; (2) approximating functions by series…

Ruckdeschel, F. R.

420

Sheetmetal. Performance Objectives. Basic Course.  

ERIC Educational Resources Information Center

Several intermediate performance objectives and corresponding criterion measures are listed for each of six terminal objectives for a basic high school sheetmetal work course. The titles of the terminal objectives are Orientation, Shop Machinery and Material, Soldering, Measurements and Layouts, Assigned Shop Projects, and Radial and Triangulation…

Murwin, Roland

421

Basic Tax Rules for Distributions  

NSDL National Science Digital Library

The legal and financial publisher Nolo Press provides this chapter entitled "Basic Tax Rules from Distributions" from their new retirement planning book IRAs, 401(k)s & Other Retirement Plans: Taking Your Money Out. The chapter covers the fundamental tax rules applicable to retirement plans, with specific attention to planning, special income tax rules, and tax rules for IRAs.

422

Play Therapy: Basics and Beyond.  

ERIC Educational Resources Information Center

This book provides an atheoretical orientation to basic concepts involved in play therapy and an introduction to different skills used in play therapy. The demand for mental professionals and school counselors who have training and expertise in using play as a therapeutic tool when working with children has increased tremendously. In response to…

Kottman, Terry

423

Basic Skills in Asian Studies.  

ERIC Educational Resources Information Center

This publication contains field tested learning activities which will help secondary students develop basic skills while learning about Asian history, culture, and geography. The activities can be used or easily adapted by teachers in any Asian studies course. The publication is organized by the skills taught. These are: reading; applying…

Hantula, James

424

Coding theory basics Toric codes  

E-print Network

. Little Department of Mathematics and Computer Science College of the Holy Cross July 29-31, 2013 John B(!) John B. Little Toric Varieties in Coding Theory #12;Coding theory basics Toric codes Tools from-up message noise encoder trans. channel rec. decoder message John B. Little Toric Varieties in Coding

Little, John B.

425

Catalog of Basic Education Systems.  

ERIC Educational Resources Information Center

This catalog is intended primarily for the use of training officers in need of prescribing basic learning programs for use by educationally disadvantaged employees, such as high school dropouts, returning veterans lacking specific academic skills, and virtually anyone with limited educational skills. In addition to academic skills, the catalog…

Civil Service Commission, Washington, DC. Bureau of Training.

426

Basic Mechanisms of the Epilepsies.  

ERIC Educational Resources Information Center

A collection of highly technical scientific articles by international basic and clinical neuroscientists constitutes a review of their knowledge of the brain and nervous system, particularly the aspects related to loss of brain function control and its explosive discharges which cause epileptic seizures. Anatomy, biophysics, biochemistry, and…

Jasper, Herbert H., Ed.; And Others

427

The Basics of Design Engineering  

NSDL National Science Digital Library

A product of Penton Publishing, The Basics of Design Engineering is a wonderful introduction to this field of engineering. The site is divided into eight chapters--Motion Control, CAD/CAM, Materials, Mechanical Systems and Components, Fluid Power, Electrical and Electronic, Fastening and Joining, and Training/Outsourcing. Each chapter is further broken into multiple sections, making information easy to access.

2000-01-01

428

Word Processing and Basic Writers.  

ERIC Educational Resources Information Center

Studies the effects of word processing on the composing processes of six basic writers. Concludes that quantity and quality of revisions are not likely to increase, that word processing initially causes many interventions in composing, and that better writers are more likely to use word processing programs in advantageous ways. (RS)

Nichols, Randall G.

1986-01-01

429

Basic Telecommunications, The Physical Layer  

NSDL National Science Digital Library

This page from Delmar Learning provides more information about the book "Basic Telecommunications, The Physical Layer" by Gary J. Mullet. The book includes information on wireline, wireless, and other fiber optic topics, focusing on physical layer implementation of system hardware. Users may order the book via this website. A link is also provided to request a review copy.

Mullett, Gary J.

2012-10-22

430

Drafting. Performance Objectives. Basic Course.  

ERIC Educational Resources Information Center

Several intermediate performance objectives and corresponding criterion measures are listed for each of 12 terminal objectives for a basic drafting course. The materials were developed for a two-semester course (2 hours daily). The organized classroom and shop experiences are designed to enable the student to develop general competencies in the…

Allen, Charles

431

Basic Instruction in Physical Education.  

ERIC Educational Resources Information Center

Chapter 1 of this monograph dealing with basic physical education instruction programs traces the history of physical education in colleges and universities from 1885 to 1985. Physical education programs became strongly entrenched within the higher education curriculum with the sanction of college administrators who recognized a responsibility to…

Priest, Laurie, Ed.

432

JSC interactive basic accounting system  

NASA Technical Reports Server (NTRS)

Design concepts for an interactive basic accounting system (IBAS) are considered in terms of selecting the design option which provides the best response at the lowest cost. Modeling the IBAS workload and applying this workload to a U1108 EXEC 8 based system using both a simulation model and the real system is discussed.

Spitzer, J. F.

1978-01-01

433

Financial Information ESTIMATED BASIC COSTS  

E-print Network

) 1,043 1,043 TOTAL $4,966 $6,240 The cost for books varies from program to program. The average cost at approximately $570. For students living off campus, actual room and meal costs may vary considerably due36 Financial Information ESTIMATED BASIC COSTS Per-semester costs for New York state residents

Suzuki, Masatsugu

434

Basic Switching George Mason University  

E-print Network

and protocols for low and high speed digital packet networks (e.g. Ethernet, Frame Relay, MPLS, MPLS L3VPNs that involve configuring switches and routers. Course Text (Optional): Data Communications and NetworkingTCOM 514 Basic Switching George Mason University Summer 2011 Class Meeting Time and Location

435

Cabinetmaking. Performance Objectives. Basic Course.  

ERIC Educational Resources Information Center

Several intermediate performance objectives and corresponding criterion measures are listed for each of 15 terminal objectives for a high school basic cabinetmaking course. The materials were developed for a two-semester (2 hours daily) course designed to develop and implement a well-grounded knowledge of the fundamentals of all phases of planning…

Harvey, Bill

436

Basic Tools for Fuzzy Modeling  

Microsoft Academic Search

The lesson will begin with the basics of fuzzy set theory. Fuzzy set theory was first introduced in 1965 by Lotfi A. Zadeh (Zadeh 1965). It may be regarded both as a generalization of classical set theory and as a generalization of dual logic. In knowledge-based methods, fuzzy sets are employed primarily to carry out the formal, content-defined mapping of

Heribert Kirschfink; Karl Lieven

437

Unions: Bread, Butter & Basic Skills.  

ERIC Educational Resources Information Center

Unions are natural providers of basic skills instruction. They are in daily workplace contact with their membership, are trusted to work on members' behalf, and speak the language of the worker. Unions are trying to address the needs of illiterate workers through collective bargaining arrangements in which employers contribute a percentage of…

BCEL Newsletter for the Business Community, 1987

1987-01-01

438

Keep Communication Professional BASIC TIPS  

E-print Network

Keep Communication Professional BASIC TIPS: Staying professional in your career is vital. You the way through your career until you retire. It's important to not become too casual when communicating with employers or other professionals while seeking an internship/co-op. Don't use slang when communicating

Gering, Jon C.

439

Wickedness, Idleness and Basic Income  

Microsoft Academic Search

This paper critically analyses the position that basic income schemes foster idleness and thereby create harm. The view is based on an alleged empirical link between idleness and violent crime and an equation of non-activity with the creation of burden for others. It will be argued that the empirical claim is weak because it relies on conjectures derived from studies

Doris Schroeder

2001-01-01

440

Starting with the Business Basics.  

ERIC Educational Resources Information Center

A nonprofit community action agency, BusinesStart, provides business training and small loans to entrepreneurs in 18 rural counties in southwestern Virginia and northeastern Tennessee. The entrepreneurs, many with no previous business experience, cite the agency's basic business training as key to their success. (SV)

Hoffman, Carl

1999-01-01

441

Radiation Related Terms Basic Terms  

E-print Network

Radiation Related Terms Basic Terms Radiation Radiation is energy in transit in the form of high not carry enough energy to separate molecules or remove electrons from atoms. Ionizing radiation Ionizing radiation is radiation with enough energy so that during an interaction with an atom, it can remove tightly

Vallino, Joseph J.

442

BASICS OF GENERALIZED PARTON DISTRIBUTIONS  

SciTech Connect

A brief review of the theory of generalized parton distributions (GPDs) is given. We discuss the basic concepts of the GPD theory and relationship between GPDs and simpler phenomenological functions, viz. form factors, parton densities and distribution amplitudes. A special emphasis is given to the formulation of GPDs in terms of double distributions.

Anatoly Radyushkin

2012-12-01

443

Negativity bias and basic values.  

PubMed

Basic values explain more variance in political attitudes and preferences than other personality and sociodemographic variables. The values most relevant to the political domain are those likely to reflect the degree of negativity bias. Value conflicts that represent negativity bias clarify differences between what worries conservatives and liberals and suggest that relations between ideology and negativity bias are linear. PMID:24970450

Schwartz, Shalom H

2014-06-01

444

The Measurement of Basic Stuff.  

ERIC Educational Resources Information Center

Seven articles contain information about measurement and evaluation in physical education and sport and complement the "Basic Stuff" series. They focus on (1) student self-assessment for exercise physiology; (2) monitoring motor development; (3) biomechanical analysis; and (4) measurements of aesthetic qualities, psychosocial characteristics, and…

Disch, James G., Ed.; And Others

1983-01-01

445

French Basic Course. Area Studies.  

ERIC Educational Resources Information Center

This volume provides the prescribed cultural background that is part of the final phase of the Basic Course in French. The texts provide the basis for discussions and personal research through which students become acquainted with various aspects of the French-speaking world and learn the referential meaning of words and expressions as they are…

Defense Language Inst., Monterey, CA.

446

Basic Mathematics Machine Calculator Course.  

ERIC Educational Resources Information Center

This series of four text-workbooks was designed for tenth grade mathematics students who have exhibited lack of problem-solving skills. Electric desk calculators are to be used with the text. In the first five chapters of the series, students learn how to use the machine while reviewing basic operations with whole numbers, decimals, fractions, and…

Windsor Public Schools, CT.

447

E47 and Id1 interplay in epithelial-mesenchymal transition.  

PubMed

E12/E47 proteins (encoded by E2A gene) are members of the class I basic helix-loop-helix (bHLH) transcription factors (also known as E proteins). E47 has been described as repressor of E-cadherin and inducer of epithelial-mesenchymal transition (EMT). We reported previously that EMT mediated by E47 in MDCK cells occurs with a concomitant overexpression of Id1 and Id3 proteins. Id proteins belong to class V of HLH factors that lack the basic domain; they dimerise with E proteins and prevent their DNA interaction, thus, acting as dominant negative of E proteins. Here, we show that E47 interacts with Id1 in E47 overexpressing MDCK cells that underwent a full EMT as well as in mesenchymal breast carcinoma and melanoma cell lines. By conducting chromatin immunoprecipitation assays we demonstrate that E47 binds directly to the endogenous E-cadherin promoter of mesenchymal MDCK-E47 cells in a complex devoid of Id1. Importantly, our data suggest that both E47 and Id1 are required to maintain the mesenchymal phenotype of MDCK-E47 cells. These data support the collaboration between E47 and Id1 in the maintenance of EMT by mechanisms independent of the dominant negative action of Id1 on E47 binding to E-cadherin promoter. Finally, the analysis of several N0 breast tumour series indicates that the expression of E47 and ID1 is significantly associated with the basal-like phenotype supporting the biological significance of the present findings. PMID:23555842

Cubillo, Eva; Diaz-Lopez, Antonio; Cuevas, Eva P; Moreno-Bueno, Gema; Peinado, Hector; Montes, Amalia; Santos, Vanesa; Portillo, Francisco; Cano, Amparo

2013-01-01

448

E47 and Id1 Interplay in Epithelial-Mesenchymal Transition  

PubMed Central

E12/E47 proteins (encoded by E2A gene) are members of the class I basic helix-loop-helix (bHLH) transcription factors (also known as E proteins). E47 has been described as repressor of E-cadherin and inducer of epithelial-mesenchymal transition (EMT). We reported previously that EMT mediated by E47 in MDCK cells occurs with a concomitant overexpression of Id1 and Id3 proteins. Id proteins belong to class V of HLH factors that lack the basic domain; they dimerise with E proteins and prevent their DNA interaction, thus, acting as dominant negative of E proteins. Here, we show that E47 interacts with Id1 in E47 overexpressing MDCK cells that underwent a full EMT as well as in mesenchymal breast carcinoma and melanoma cell lines. By conducting chromatin immunoprecipitation assays we demonstrate that E47 binds directly to the endogenous E-cadherin promoter of mesenchymal MDCK-E47 cells in a complex devoid of Id1. Importantly, our data suggest that both E47 and Id1 are required to maintain the mesenchymal phenotype of MDCK-E47 cells. These data support the collaboration between E47 and Id1 in the maintenance of EMT by mechanisms independent of the dominant negative action of Id1 on E47 binding to E-cadherin promoter. Finally, the analysis of several N0 breast tumour series indicates that the expression of E47 and ID1 is significantly associated with the basal-like phenotype supporting the biological significance of the present findings. PMID:23555842

Cubillo, Eva; Moreno-Bueno, Gema; Peinado, Hector; Montes, Amalia; Santos, Vanesa; Portillo, Francisco; Cano, Amparo

2013-01-01

449

Basic statistics in cell biology.  

PubMed

The physicist Ernest Rutherford said, "If your experiment needs statistics, you ought to have done a better experiment." Although this aphorism remains true for much of today's research in cell biology, a basic understanding of statistics can be useful to cell biologists to help in monitoring the conduct of their experiments, in interpreting the results, in presenting them in publications, and when critically evaluating research by others. However, training in statistics is often focused on the sophisticated needs of clinical researchers, psychologists, and epidemiologists, whose conclusions depend wholly on statistics, rather than the practical needs of cell biologists, whose experiments often provide evidence that is not statistical in nature. This review describes some of the basic statistical principles that may be of use to experimental biologists, but it does not cover the sophisticated statistics needed for papers that contain evidence of no other kind. PMID:25000992

Vaux, David L

2014-10-11

450

Nick Reeder's Basic Electronics Courses  

NSDL National Science Digital Library

This site is from Sinclair community college posted by instructor Nick Reeder. A review of some basic electronics courses, with over 1100 self-test questions, the site contains great resources for students and teacher