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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The DDT1 MF2 smooth muscle tumor cell line was derived from an estrogen/androgen-induced leiomyosarcoma that arose in the ductus deferens of a Syrian hamster. The growth of this cell line is arrested at the G0/G1 phase of the cell cycle after treatment with glucocorticoids. To identify the putative gene(s) that are potentially involved in this hormone-induced cell growth arrest, we have used a differential screening technique to clone those genes whose expression is induced or up-regulated by glucocorticoids. A number of glucocorticoid response genes were thereby isolated from the leiomyosarcoma cells. One of these clones, termed TA16, was found to be markedly up-regulated by glucocorticoids in DDT1 MF2 cells, but only marginally changed in GR1 cells, a glucocorticoid-resistant variant that was selected from the wild type DDT1 MF2 cell. Isolation and sequencing of its intact cDNA indicated that the TA16 encodes a protein 485 amino acids long, and its sequence is closely homologous to a novel transcriptional repressor that presumably represses the transcription activity of some zinc finger transcriptional factors through a direct interaction. Transfection assays demonstrated that introduction of an antisense TA16 cDNA expression vector, controlled by an MMTV promoter, into the DDT1 MF2 cell significantly relieved the glucocorticoid-induced cell growth arrest. This finding suggests that TA16 might participate in the mediation of glucocorticoid-induced cell cycle arrest in leiomyosarcoma cells.
Mol Endocrinol 1997 Aug
PMID:Molecular cloning of TA16, a transcriptional repressor that may mediate glucocorticoid-induced growth arrest of leiomyosarcoma cells. 925 24

The yeast transcriptional repressor Tup1 contains seven WD repeats which interact with the DNA-binding protein alpha2. We have identified mutations in Tup1 that disrupt this interaction. The positions of the amino acids changed by these mutations are consistent with Tup1 being folded into a seven-bladed propeller like that formed by another WD repeat-containing protein, the beta subunit of the heterotrimeric G protein used in signal transduction. Our results also indicate that the interaction between Tup1 and alpha2 resembles the interaction between Gbeta and G alpha, suggesting that a similar structural interface is formed by WD repeat proteins that are used in both transcriptional regulation and signal transduction.
Mol Cell Biol 1997 Oct
PMID:Residues in the WD repeats of Tup1 required for interaction with alpha2. 931 61

We have identified Xbp1 (XhoI site-binding protein 1) as a new DNA-binding protein with homology to the DNA-binding domain of the Saccharomyces cerevisiae cell cycle regulating transcription factors Swi4 and Mbp1. The DNA recognition sequence was determined by random oligonucleotide selection and confirmed by gel retardation and footprint analyses. The consensus binding site of Xbp1, GcCTCGA(G/A)G(C/A)g(a/g), is a palindromic sequence, with an XhoI restriction enzyme recognition site at its center. This Xbpl binding site is similar to Swi4/Swi6 and Mbp1/Swi6 binding sites but shows a clear difference from these elements in one of the central core bases. There are binding sites for Xbp1 in the G1 cyclin promoter (CLN1), but they are distinct from the Swi4/Swi6 binding sites in CLN1, and Xbp1 will not bind to Swi4/Swi6 or Mbp1/Swi6 binding sites. The XBP1 promoter contains several stress-regulated elements, and its expression is induced by heat shock, high osmolarity, oxidative stress, DNA damage, and glucose starvation. When fused to the LexA DNA-binding domain, Xbp1 acts as transcriptional repressor, defining it as the first repressor in the Swi4/Mbp1 family and the first potential negative regulator of transcription induced by stress. Overexpression of XBP1 results in a slow-growth phenotype, lengthening of G1, an increase in cell volume, and a repression of G1 cyclin expression. These observations suggest that Xbp1 may contribute to the repression of specific transcripts and cause a transient cell cycle delay under stress conditions.
Mol Cell Biol 1997 Nov
PMID:Xbp1, a stress-induced transcriptional repressor of the Saccharomyces cerevisiae Swi4/Mbp1 family. 934 12

The Drosophila extra sex combs (esc) protein, a member of the Polycomb group (PcG), is a transcriptional repressor of homeotic genes. Genetic studies have shown that esc protein is required in early embryos at about the time that other PcG proteins become engaged in homeotic gene repression. The esc protein consists primarily of multiple copies of the WD repeat, a motif that has been implicated in protein-protein interaction. To further investigate the domain organization of esc protein, we have isolated and characterized esc homologs from divergent insect species. We report that esc protein is highly conserved in housefly (72% identical to Drosophila esc), butterfly (55% identical), and grasshopper (56% identical). We show that the butterfly homolog provides esc function in Drosophila, indicating that the sequence similarities reflect functional conservation. Homology modeling using the crystal structure of another WD repeat protein, the G-protein beta-subunit, predicts that esc protein adopts a beta-propeller structure. The sequence comparisons and modeling suggest that there are seven WD repeats in esc protein which together form a seven-bladed beta-propeller. We locate the conserved regions in esc protein with respect to this predicted structure. Site-directed mutagenesis of specific loops, predicted to extend from the propeller surface, identifies conserved parts of esc protein required for function in vivo. We suggest that these regions might mediate physical interaction with esc partner proteins.
Mol Cell Biol 1997 Nov
PMID:Evolutionary conservation and predicted structure of the Drosophila extra sex combs repressor protein. 934 30

Recently, we demonstrated that the function of ATF3, a stress-inducible transcriptional repressor, is negatively regulated by a bZip protein, gadd153/Chop10. In this report, we present evidence that ATF3 can repress the expression of its own inhibitor, gadd153/Chop10. First, ATF3 represses a chloramphenicol acetyltransferase reporter gene driven by the gadd153/Chop10 promoter when assayed by a transfection assay in vivo and a transcription assay in vitro. Second, the gadd153/Chop10 promoter contains two functionally important binding sites for ATF3: an AP-1 site and a C/EBP-ATF composite site, a previously unidentified binding site for ATF3. The absence of either site reduces the ability of ATF3 to repress the promoter. Third, overexpression of ATF3 by transient transfection results in a reduction of the endogenous gadd153/Chop10 mRNA level. Fourth, as described previously, ATF3 is induced in the liver upon CCl4 treatment. Intriguingly, we show in this report that gadd153/Chop10 mRNA is not present in areas where ATF3 is induced. Taken together, these results strongly suggest that ATF3 represses the expression of gadd153/Chop10. The mutual negative regulation between ATF3 and gadd153/Chop10 is discussed.
Mol Cell Biol 1997 Nov
PMID:gadd153/Chop10, a potential target gene of the transcriptional repressor ATF3. 934 34

In this report we show that the ENA1/PMR2A gene is under glucose repression. The SNF1 protein kinase, acting independently from the HOG and calcineurin pathways, is essential to release ENA1 from glucose repression. The transcriptional repressor Ssn6p negatively regulates ENA1 expression and, like other glucose repressible genes, this repression is mediated in part by Mig1p. Deletion of a fragment from the ENA1 promoter that includes two Mig1p consensus binding sites gives a high level of expression in glucose without added salt. We suggest that regulation of ENA1 by the SNF1 pathway could be part of a general mechanism through which yeast cells respond to carbon source starvation by activating protective systems against different types of stress.
Mol Microbiol 1997 Oct
PMID:Glucose repression affects ion homeostasis in yeast through the regulation of the stress-activated ENA1 gene. 938 92

The yeast SIN3 gene functions as a transcriptional repressor, despite the fact that Sin3p does not bind DNA directly. We have conducted a two-hybrid screen to look for proteins that interact with Sin3p, using the PAH2 domain of Sin3p as bait. Five new genes, STB1-STB5 were identified, as well as the STB6 gene, which is similar to STB2. STB1, STB2, STB3, and STB6 are novel genes, and STB4 and STB5 encode C6 zinc cluster DNA-binding proteins. None of these genes is essential for viability, and several of these genes may encode transcriptional activators. Several special problems were encountered in using a transcriptional repressor in a two-hybrid screen. For example, the STB genes will interact with a LexA-Sin3(PAH2) fusion protein containing a region of Sin3p, but a LexA-Sin3p fusion protein containing full-length Sin3p, along with a STB clone, does not produce two-hybrid activation of a transcriptional reporter. In addition, a sin3 mutation reduces the transcriptional activation by two-hybrid partners, suggesting that a sin3 mutation reduces the transcriptional efficiency of the Gal4p and VP16 activation domains. We have shown previously that Sin3p is part of a large multiprotein complex, and we show here that Stb1p and Stb2p are present in this complex.
Mol Gen Genet 1997 Oct
PMID:Identification of the Saccharomyces cerevisiae genes STB1-STB5 encoding Sin3p binding proteins. 939 35

The Escherichia coli nucleoid protein, H-NS, functions as a global regulator for expression of a wide variety of genes. We recently analyzed the structure-function relationship of H-NS with special reference to the domains responsible for transcriptional repression and DNA-binding, respectively. However, identification of the presumed dimerization domain of H-NS and its functional significance was elusive. To address this particular issue, we first examined a set of N-terminally or C-terminally truncated forms of H-NS, in terms of their so-called dominant-negative effect on the in vivo function of the wild-type H-NS. The results showed that certain truncated forms exhibit such a dominant-negative effect, but others did not. As judged by the results of the dominant-negative effect, it was assumed that a relatively central portion of H-NS extending from residues 21 to 63 is involved in dimerization. This was confirmed by an in vitro chemical cross-linking analysis and a gel filtration analysis with these truncated forms of H-NS. Furthermore, the use of the dominant-negative phenotype, caused by a truncated form of H-NS (named N91), allowed us to isolate a missense mutant, which was expected to be specifically defective in dimerization. This mutant had an amino acid substitution at position 30 (Leu30 to Pro) in N91 consisting of the N-terminal 91 amino acids of H-NS. This mutant was indeed defective in the in vitro ability to form a heterodimer with the wild-type H-NS. When this particular single amino acid substitution was introduced into the full-length H-NS, the resultant H-NS mutant had lost the ability to form dimers in vitro and to function as a transcriptional repressor. These findings collectively provided us with evidence that the ability of H-NS to form a dimer is crucial for H-NS to function as a transcriptional repressor.
J Mol Biol 1997 Nov 28
PMID:Clarification of the dimerization domain and its functional significance for the Escherichia coli nucleoid protein H-NS. 939 22

The cellular aging-associated transcriptional repressor that we previously named as Orpheus was identical to Oct-1, a member of the POU domain family. Oct-1 represses the collagenase gene, one of the cellular aging-associated genes, by interacting with an AT-rich cis-element in the upstream of the gene in preimmortalized cells at earlier population-doubling levels and in immortalized cells. In these stages of cells, considerable fractions of the Oct-1 protein were prominently localized in the nuclear periphery and colocalized with lamin B. During the cellular aging process, however, this subspecies of Oct-1 disappeared from the nuclear periphery. The cells lacking the nuclear peripheral Oct-1 protein exhibited strong collagenase expression and carried typical senescent morphologies. Concomitantly, the binding activity and the amount of nuclear Oct-1 protein were reduced in the aging process and resumed after immortalization. However, the whole cellular amounts of Oct-1 protein were not significantly changed during either process. Thus, the cellular aging-associated genes including the collagenase gene seemed to be derepressed by the dissociation of Oct-1 protein from the nuclear peripheral structure. Oct-1 may form a transcriptional repressive apparatus by anchoring nuclear matrix attachment regions onto the nuclear lamina in the nuclear periphery.
Mol Biol Cell 1997 Dec
PMID:Dissociation of Oct-1 from the nuclear peripheral structure induces the cellular aging-associated collagenase gene expression. 939 64

Synthesis of the Yop proteins by yersiniae is downregulated when secretion is prevented by closure or destruction of the contact (type III) secretion channel. In Yersinia pseudotuberculosis, a mutation in the IcrQ gene, encoding a secreted protein, reduces this feedback inhibition mechanism. Surprisingly, mutation in the yscM gene, the IcrQ homologue in Y. enterocolitica, does not lead to the same deregulated phenotype. In this paper, we addressed the question of this discrepancy. We found a new gene on the Y. enterocolitica pYV plasmid that encodes a protein with 57% identity to YscM (now called YscM1). Overexpression of this gene, called yscM2, like overexpression of IcrQ and yscM1, blocked Yop secretion. A double yscM1, yscM2 mutant had the same phenotype as that of the IcrQ mutant. The discrepancy can thus be explained by the existence of two functionally equivalent copies of yscM in Y. enterocolitica. Overexpression of yscM1 drastically reduced the expression of a yopH-cat reporter gene when tested in a pYV+ background. However, no effect could be observed in the absence of a pYV plasmid, indicating that YscM1 does not act directly as a transcriptional repressor or as an anti-VirF factor. We have also ruled out that YscM acts by obstructing the secretion channel.
Mol Microbiol 1997 Nov
PMID:YscM1 and YscM2, two Yersinia enterocolitica proteins causing downregulation of yop transcription. 942 12


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