scholarly journals Interactions between Hairy/Enhancer of Split-related proteins and the pancreatic transcription factor Ptf1-p48 modulate function of the PTF1 transcriptional complex

2006 ◽  
Vol 393 (3) ◽  
pp. 679-685 ◽  
Author(s):  
Bidyut Ghosh ◽  
Steven D. Leach
Keyword(s):  
Transcription Factor ◽  
Family Members ◽  
Direct Interaction ◽  
Inhibitory Effect ◽  
Effector Proteins ◽  
Glutathione S Transferase ◽  
Modulate Function ◽  
Helix Loop Helix ◽  
Transcriptional Complex ◽  
Enhancer Of Split

In the developing pancreas, the onset of exocrine differentiation is driven by the activity of the PTF1 (pancreas transciption factor 1) transcriptional complex, which is comprised of the class II bHLH (basic helix–loop–helix) protein, Ptf1-p48 [also known as Ptf1a (pancreas specific transcription factor 1a)], and a class I E-box binding partner. Activity of the PTF1 complex is normally inhibited by the Notch signalling pathway, a process mediated by Notch effector proteins in the HES (Hairy/Enhancer of Split) family of bHLH transcriptional repressors. In the present study, we show that this inhibitory effect occurs through direct interaction between HES family members and Ptf1-p48. The HES family members Hey1 (hairy/enhancer-of-split related with YRPW motif 1) and Hey2 co-immunoprecipitate with Ptf1-p48, and Ptf1-p48 binding by Hes1 is also evident in yeast two-hybrid and GST (glutathione S-transferase) pull-down assays. The ability of Hes1 to interact with Ptf1-p48 resides within a fragment comprised of the bHLH, Orange and C-terminal domains, and does not require the N-terminal or WRPW elements. The ability of truncated versions of Hes1 to bind Ptf1-p48 correlates with their ability to down-regulate the activity of the PTF1 transcriptional complex, defining Ptf1-p48 binding as the most likely mechanism by which Notch effector proteins delay exocrine pancreatic differentiation.

scholarly journals Role Played by Microphthalmia Transcription Factor Phosphorylation and Its Zip Domain in Its Transcriptional Inhibition by PIAS3

2003 ◽  
Vol 23 (24) ◽  
pp. 9073-9080 ◽  
Author(s):  
Carmit Levy ◽  
Amir Sonnenblick ◽  
Ehud Razin
Keyword(s):  
Transcription Factor ◽  
Transcriptional Activity ◽  
Leucine Zipper ◽  
Direct Interaction ◽  
Inhibitory Effect ◽  
Cell Library ◽  
Helix Loop Helix ◽  
Associated Proteins ◽  
Microphthalmia Transcription Factor

ABSTRACT Mutation of microphthalmia transcription factor (MITF) results in deafness, bone loss, small eyes, and poorly pigmented eyes and skin. A search for MITF-associated proteins, using a mast cell library that was screened with a construct that encodes the basic helix-loop-helix leucine zipper (Zip) domain of MITF, resulted in the isolation of the STAT3 inhibitor, PIAS3. PIAS3 functions in vivo as a key molecule in suppressing the transcriptional activity of MITF. Here, we report that the Zip domain is the region of MITF that is involved in the direct interaction between MITF and PIAS3. Additionally, we investigated the effect of phosphorylation of MITF on its interaction with PIAS3. We found that phosphorylation of MITF on serines in positions 73 and 409 plays an important role in its association with PIAS3. This effect was profound with phosphorylation on Ser409, which significantly reduced the inhibitory effect of PIAS3 on MITF and also modulated the transcriptional activity of MITF. Thus, phosphorylation of MITF could be considered a fine, and alternative, tuning of its transcriptional machinery.

Inhibitory Effect of the Transcription Factor Encoded by themi Mutant Allele in Cultured Mast Cells of Mice

Blood ◽  
1999 ◽  
Vol 93 (4) ◽  
pp. 1189-1196 ◽  
Author(s):  
Akihiko Ito ◽  
Eiichi Morii ◽  
Dae-Ki Kim ◽  
Tatsuki R. Kataoka ◽  
Tomoko Jippo ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Mast Cells ◽  
Leucine Zipper ◽  
Tryptophan Hydroxylase ◽  
Cdna Probe ◽  
Inhibitory Effect ◽  
Northern Analysis ◽  
Helix Loop Helix ◽  
Genes Encoding ◽  
Mouse Mast Cell

The mi locus of mice encodes a transcription factor of the basic-helix-loop-helix-leucine zipper protein family (MITF). The MITF encoded by the mutant mi allele (mi-MITF) deletes 1 of 4 consecutive arginines in the basic domain. The mice of mi/migenotype express mi-MITF, whereas the mice of tg/tggenotype have a transgene at the 5′ flanking region of themi gene and do not express any MITF. To investigate the function of mi-MITF in cultured mast cells (CMCs), we took two approaches. First, mRNA obtained from mi/mi CMCs ortg/tg CMCs was subtracted from complementary (c) DNA library of normal (+/+) CMCs, and the (+/+-mi/mi) and (+/+-tg/tg) subtraction libraries were obtained. When the number of clones that hybridized more efficiently with +/+ CMC cDNA probe than with mi/mi or tg/tg CMC cDNA probe was compared using Southern analysis, the number was larger in the (+/+-mi/mi) library than in the (+/+-tg/tg) library. Second, we compared mRNA expression of six genes betweenmi/mi and tg/tg CMCs by Northern analysis. The transcription of three genes encoding mouse mast cell proteases was impaired in both mi/mi and tg/tg CMCs. On the other hand, the transcription of three genes encoding c-kit receptor, tryptophan hydroxylase, and granzyme B was markedly reduced inmi/mi CMCs, but the reduction was significantly smaller intg/tg CMCs. These results indicated the inhibitory effect ofmi-MITF on the transactivation of particular genes in CMCs.

Hypoxic induction ofCtgfis directly mediated by Hif-1

2004 ◽  
Vol 287 (6) ◽  
pp. F1223-F1232 ◽  
Author(s):  
Debra F. Higgins ◽  
Mangatt P. Biju ◽  
Yasuhiro Akai ◽  
Anton Wutz ◽  
Randall S. Johnson ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Renal Fibrosis ◽  
Transforming Growth Factor ◽  
Hypoxia Inducible Factor ◽  
Direct Interaction ◽  
Tubular Epithelial Cell ◽  
Hypoxic Induction ◽  
Helix Loop Helix ◽  
Expression Of Genes ◽  
Fibrotic Disorders

CTGF plays a significant role in the development of renal fibrosis by mediating the fibrotic effects of transforming growth factor (TGF)-β1and has been shown to be hypoxia inducible in human breast cancer cells. It has been suggested that hypoxia is an important underlying cause for the development of renal fibrosis through the modulation of profibrotic genes. One of the key mediators of the cell's response to lowered oxygen environments is hypoxia-inducible-factor-1 (HIF-1), a basic helix-loop-helix transcription factor, which enables cells to adapt to hypoxia by regulating the expression of genes involved in increasing oxygen availability ( VEGF, erythropoietin) and enhancing glucose uptake and metabolism ( Glut-1, PGK). In this paper, we have used primary tubular epithelial cell cultures from a tetracycline-inducible- Hif- 1α knockout murine model to further elucidate the role of Hif-1 in the hypoxic-induction of Ctgf expression. We show that hypoxia response elements present upstream of Ctgf enable direct interaction of Hif-1 transcription factor with the Ctgf promoter, resulting in increased transcription of Ctgf mRNA. Cells deficient in Hif- 1α were incapable of inducing Ctgf mRNA in response to hypoxia, suggesting an absolute requirement of Hif-1. Furthermore, the observed Hif-1-mediated hypoxic stimulation of Ctgf expression was found to occur independently of TGF-β1signaling. Our findings have important implications for a number of fibrotic disorders in which hypoxia, CTGF, and TGF-β1are involved, including renal, dermal, hepatic, and pulmonary fibrosis.

Inhibitory effect of the transcription factor encoded by the mutant mi microphthalmia allele on transactivation of mouse mast cell protease 7 gene

Blood ◽  
2001 ◽  
Vol 97 (3) ◽  
pp. 645-651 ◽  
Author(s):  
Hideki Ogihara ◽  
Eiichi Morii ◽  
Dae-Ki Kim ◽  
Keisuke Oboki ◽  
Yukihiko Kitamura
Keyword(s):  
Transcription Factor ◽  
Mast Cell ◽  
Inhibitory Effect ◽  
Chromosome 17 ◽  
Binding Motif ◽  
Mast Cell Protease ◽  
Coding Regions ◽  
Helix Loop Helix ◽  
Negative Effect ◽  
Mouse Mast Cell

Abstract The transcription factor encoded by the mi locus (MITF) is a transcription factor of the basic-helix-loop-helix zipper protein family. Mice of mi/mi genotype express a normal amount of abnormal MITF, whereas mice oftg/tg genotype do not express any MITFs due to the transgene insertional mutation. The effect of normal (+) and mutant (mi) MITFs on the expression of mouse mast cell protease (MMCP) 6 and 7 was examined. Both MMCP-6 and MMCP-7 are tryptases, and their coding regions with high homology are closely located on chromosome 17. Both MMCP-6 and MMCP-7 genes are expressed in normal cultured mast cells (+/+ CMCs). Although the transcription of MMCP-6 gene was severely suppressed in bothmi/mi and tg/tg CMCs, that of MMCP-7 gene was severely suppressed only in mi/mi CMCs. The study identified the most significant segment for the transcription in the 5′ flanking region of MMCP-7 gene. Unexpectedly, no CANNTG motifs were found that are recognized and bound by +-MITF in this segment. Instead, there was an AP-1 binding motif, and binding of c-Jun to the AP-1 motif significantly enhanced the transcription of MMCP-7 gene. The complex formation of c-Jun with either +-MITF ormi-MITF was demonstrated. The binding of +-MITF to c-Jun enhanced the transactivation of MMCP-7 gene, and that ofmi-MITF suppressed the transactivation. Although the former complex was located only in the nucleus, the latter complex was predominantly found in the cytoplasm. The negative effect ofmi-MITF on the transcription of MMCP-7 gene appeared to be executed through the interaction with c-Jun.

scholarly journals Expression of Novel ING Variants Is Regulated by Thyroid Hormone in theXenopus laevisTadpole

2001 ◽  
Vol 276 (50) ◽  
pp. 47013-47020 ◽  
Author(s):  
Mary J. Wagner ◽  
Markéta Gogela-Spehar ◽  
Rachel C. Skirrow ◽  
Randal N. Johnston ◽  
Karl Riabowol ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Thyroid Hormone ◽  
Cell Fate ◽  
Splice Variants ◽  
Family Members ◽  
Specific Pattern ◽  
Protein Isoforms ◽  
Modulate Function ◽  
Western Blots ◽  
Tissue Specific

The candidate tumor suppressor gene,ING1, encodes several protein isoforms as a result of alternative splicing that may possess agonistic and antagonistic roles in the control of cell proliferation and apoptosis. Recently a related gene,ING2, was isolated in human whose expression is increased in adenocarcinomas. Little is known about the cellular function and regulation of these ING family members, but the fact that ING proteins contain a plant homeodomain finger suggests that these proteins may modulate transcription factor-mediated pathways. To elucidate how ING may interact in different tissues to modulate function, we used amphibian metamorphosis as a model system in which a single stimulus, thyroid hormone (TH), initiates tissue-specific proliferation, differentiation, and apoptosis. We have isolated the firstXenopus laevis ING2and demonstrate that transcript levels increase in response to TH treatment. We provide evidence for the existence of splice variants that are differentially expressed in tissues with different TH-induced fates. Western blots using an antibody directed against the highly conserved C-terminal end of ING proteins reveal a tissue-specific pattern of ING isoform expression in adultXenopustissues. Analyses of premetamorphic tadpole tissues show a TH-induced accumulation of ING proteins in tail, whereas the levels in the leg are not affected. This TH-induced accumulation is also observed in serum-free tail organ cultures and is prevented by inhibitors of tail apoptosis. Therefore, this work presents the first link between ING expression and a hormonally regulated nuclear transcription factor-mediated apoptotic response opening the possibility that ING family members may be involved in transducing the signal initiated by TH that determines cell fate.

A Bacterial Effector Acts as a Plant Transcription Factor and Induces a Cell Size Regulator

Science ◽  
2007 ◽  
Vol 318 (5850) ◽  
pp. 648-651 ◽  
Author(s):  
Sabine Kay ◽  
Simone Hahn ◽  
Eric Marois ◽  
Gerd Hause ◽  
Ulla Bonas
Keyword(s):  
Transcription Factor ◽  
Cell Size ◽  
Effector Proteins ◽  
Host Cells ◽  
Mesophyll Cells ◽  
Eukaryotic Transcription ◽  
Helix Loop Helix ◽  
Host Signaling ◽  
A Cell ◽  
Developmental Reprogramming

Pathogenicity of many Gram-negative bacteria relies on the injection of effector proteins by type III secretion into eukaryotic cells, where they modulate host signaling pathways to the pathogen's benefit. One such effector protein injected by Xanthomonas into plants is AvrBs3, which localizes to the plant cell nucleus and causes hypertrophy of plant mesophyll cells. We show that AvrBs3 induces the expression of a master regulator of cell size, upa20, which encodes a transcription factor containing a basic helix-loop-helix domain. AvrBs3 binds to a conserved element in the upa20 promoter via its central repeat region and induces gene expression through its activation domain. Thus, AvrBs3 and likely other members of this family provoke developmental reprogramming of host cells by mimicking eukaryotic transcription factors.

Inhibitory Effect of the Transcription Factor Encoded by themi Mutant Allele in Cultured Mast Cells of Mice

Blood ◽  
1999 ◽  
Vol 93 (4) ◽  
pp. 1189-1196 ◽  
Author(s):  
Akihiko Ito ◽  
Eiichi Morii ◽  
Dae-Ki Kim ◽  
Tatsuki R. Kataoka ◽  
Tomoko Jippo ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Mast Cells ◽  
Leucine Zipper ◽  
Tryptophan Hydroxylase ◽  
Cdna Probe ◽  
Inhibitory Effect ◽  
Northern Analysis ◽  
Helix Loop Helix ◽  
Genes Encoding ◽  
Mouse Mast Cell

Abstract The mi locus of mice encodes a transcription factor of the basic-helix-loop-helix-leucine zipper protein family (MITF). The MITF encoded by the mutant mi allele (mi-MITF) deletes 1 of 4 consecutive arginines in the basic domain. The mice of mi/migenotype express mi-MITF, whereas the mice of tg/tggenotype have a transgene at the 5′ flanking region of themi gene and do not express any MITF. To investigate the function of mi-MITF in cultured mast cells (CMCs), we took two approaches. First, mRNA obtained from mi/mi CMCs ortg/tg CMCs was subtracted from complementary (c) DNA library of normal (+/+) CMCs, and the (+/+-mi/mi) and (+/+-tg/tg) subtraction libraries were obtained. When the number of clones that hybridized more efficiently with +/+ CMC cDNA probe than with mi/mi or tg/tg CMC cDNA probe was compared using Southern analysis, the number was larger in the (+/+-mi/mi) library than in the (+/+-tg/tg) library. Second, we compared mRNA expression of six genes betweenmi/mi and tg/tg CMCs by Northern analysis. The transcription of three genes encoding mouse mast cell proteases was impaired in both mi/mi and tg/tg CMCs. On the other hand, the transcription of three genes encoding c-kit receptor, tryptophan hydroxylase, and granzyme B was markedly reduced inmi/mi CMCs, but the reduction was significantly smaller intg/tg CMCs. These results indicated the inhibitory effect ofmi-MITF on the transactivation of particular genes in CMCs.

scholarly journals Regulation of Swarming Motility and flhDCSm Expression by RssAB Signaling in Serratia marcescens

2008 ◽  
Vol 190 (7) ◽  
pp. 2496-2504 ◽  
Author(s):  
Po-Chi Soo ◽  
Yu-Tze Horng ◽  
Jun-Rong Wei ◽  
Jwu-Ching Shu ◽  
Chia-Chen Lu ◽  
...  
Keyword(s):  
Serratia Marcescens ◽  
Binding Site ◽  
Promoter Region ◽  
Transcriptional Start Site ◽  
Direct Interaction ◽  
Underlying Mechanism ◽  
Inhibitory Effect ◽  
Start Codon ◽  
Mobility Shift

ABSTRACT Serratia marcescens cells swarm at 30°C but not at 37°C, and the underlying mechanism is not characterized. Our previous studies had shown that a temperature upshift from 30 to 37°C reduced the expression levels of flhDCSm and hagSm in S. marcescens CH-1. Mutation in rssA or rssB, cognate genes that comprise a two-component system, also resulted in precocious swarming phenotypes at 37°C. To further characterize the underlying mechanism, in the present study, we report that expression of flhDCSm and synthesis of flagella are significantly increased in the rssA mutant strain at 37°C. Primer extension analysis for determination of the transcriptional start site(s) of flhDCSm revealed two transcriptional start sites, P1 and P2, in S. marcescens CH-1. Characterization of the phosphorylated RssB (RssB∼P) binding site by an electrophoretic mobility shift assay showed direct interaction of RssB∼P, but not unphosphorylated RssB [RssB(D51E)], with the P2 promoter region. A DNase I footprinting assay using a capillary electrophoresis approach further determined that the RssB∼P binding site is located between base pair positions −341 and −364 from the translation start codon ATG in the flhDCSm promoter region. The binding site overlaps with the P2 “−35” promoter region. A modified chromatin immunoprecipitation assay was subsequently performed to confirm that RssB∼P binds to the flhDCSm promoter region in vivo. In conclusion, our results indicated that activated RssA-RssB signaling directly inhibits flhDCSm promoter activity at 37°C. This inhibitory effect was comparatively alleviated at 30°C. This finding might explain, at least in part, the phenomenon of inhibition of S. marcescens swarming at 37°C.

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