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Repression Domain (repression + domain)
Selected AbstractsBiological activity of RE-1 silencing transcription factor (REST) towards distinct transcriptional activatorsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2001Michael Lietz Abstract The zinc finger protein RE-1 silencing transcription factor (REST) is a transcriptional repressor that represses neuronal genes in non-neuronal tissues. We have analyzed the ability of REST and the REST mutants, REST,N and REST,C lacking either the N-terminal or C-terminal repression domains of REST, to inhibit transcription mediated by distinct transcriptional activator proteins. For this purpose we have designed an activator specific assay where transcription is activated as a result of only one distinct activation domain. In addition, binding sites for REST were inserted in the 5,-untranslated region or at a distant position downstream of the polyadenylation signal. The results show that REST or the REST mutants containing only one repression domain were able to block transcriptional activation mediated by the transcriptional activation domains derived from p53, AP2, Egr-1, and GAL4. Moreover, REST, as well as the REST mutants, blocked the activity of the phosphorylation-dependent activation domain of Elk1. However, the activity of the activation domain derived from cAMP response element binding protein 2 (CREB2), was not inhibited by REST, REST,N or REST,C, suggesting that REST is able to distinguish between distinct transcriptional activation domains. Additionally, the activator specific assay, together with a positive-dominant mutant of REST that activated instead of repressed transcription, was used in titration experiments to show that REST has transcriptional repression and no transcriptional activation properties when bound to the 5,-untranslated region of a gene. [source] Modulation of glucocorticoid receptor-interacting protein 1 (GRIP1) transactivation and co-activation activities through its C-terminal repression and self-association domainsFEBS JOURNAL, Issue 10 2006Pei-Yao Liu Glucocorticoid receptor-interacting protein 1 (GRIP1), a p160 family nuclear receptor co-activator, possesses at least two autonomous activation domains (AD1 and AD2) in the C-terminal region. AD1 activity appears to be mediated by CBP/p300, whereas AD2 activity is apparently mediated through co-activator-associated arginine methyltransferase 1 (CARM1). The mechanisms responsible for regulating the activities of AD1 and AD2 are not well understood. We provide evidence that the GRIP1 C-terminal region may be involved in regulating its own transactivation and nuclear receptor co-activation activities through primary self-association and a repression domain. We also compared the effects of the GRIP1 C terminus with those of other factors that functionally interact with the GRIP1 C terminus, such as CARM1. Based on our results, we propose a regulatory mechanism involving conformational changes to GRIP1 mediated through its intramolecular and intermolecular interactions, and through modulation of the effects of co-repressors on its repression domains. These are the first results to indicate that the structural components of GRIP1, especially those of the C terminus, might functionally modulate its putative transactivation activities and nuclear receptor co-activator functions. [source] The Ikaros family protein Eos associates with C-terminal-binding protein corepressorsFEBS JOURNAL, Issue 23 2002José Perdomo Eos is a zinc finger transcription factor of the Ikaros family. It binds typical GGGAA Ikaros recognition sites in DNA and functions as a transcriptional repressor. Here we show that Eos associates with the corepressor C-terminal-binding protein (CtBP). CtBP has previously been shown to bind Pro-X-Asp-Leu-Ser (PXDLS) motifs in several DNA-binding proteins. We note that Eos contains a related motif PEDLA, and we demonstrate that CtBP can bind this site weakly but that it also contacts additional regions of Eos. Consistent with this finding, mutation of the PEDLA motif does not negate CtBP binding or CtBP-mediated repression by Eos. CtBP has previously been shown to bind to a PXDLS-type motif in Ikaros, and we show that another Ikaros-related protein TRPS1 also contains a PXDLS CtBP contact motif within its repression domain. We conclude that several Ikaros family proteins utilize CtBP corepressors to inhibit gene expression. [source] MLL/GRAF fusion in an infant acute monocytic leukemia (AML M5b) with a cytogenetically cryptic ins(5;11)(q31;q23q23)GENES, CHROMOSOMES AND CANCER, Issue 4 2004Ioannis Panagopoulos More than 30 fusions involving the MLL gene at 11q23 have been reported in acute myeloid leukemia (AML). Some of these chimeras are rather common, such as MLL/MLLT3(AF9), but many are quite rare, with some, for example, MLL/GRAF, described only in a single case. The MLL/GRAF fusion, in which the reciprocal hybrid was not expressed, suggesting that the former transcript was the leukemogenic one, was detected in a juvenile myelomonocytic leukemia with a t(5;11)(q31;q23). Here, we report a second case,an infant acute monocytic leukemia (AML M5b),with an MLL/GRAF fusion. By conventional G-banding, the karyotype was normal. However, Southern blot and fluorescence in situ hybridization analyses revealed that MLL was rearranged and that the 5, part of the MLL gene was inserted into 5q in the vicinity of 5q31, which harbors GRAF. Reverse-transcriptase polymerase chain reaction (PCR) showed that exon 9 of MLL was fused in-frame with exon 19 of GRAF. Extralong genomic PCR with subsequent sequence analysis demonstrated that the breakpoints occurred in intron 9 of MLL, nine base pairs (bp) downstream from exon 9, and in intron 18 of GRAF, 117 bp downstream from exon 18. A 6-bp insertion (ACACTC) of unknown origin was present at the junction. The putative MLL/GRAF fusion protein would retain the AT-hook DNA-binding domain, the DNA methyl transferase motif, the transcription repression domain of MLL, and the SH3 domain of GRAF. As expected, the reciprocal GRAF/MLL was neither expressed nor generated at the genomic level as a consequence of the ins(5;11)(q31;q23q23). On the basis of the now-reported two cases with MLL/GRAF, we conclude that this transcript,but not the reciprocal one,characterizes a rare genetic subgroup of infant AML. © 2004 Wiley-Liss, Inc. [source] The E8 repression domain can replace the E2 transactivation domain for growth inhibition of HeLa cells by papillomavirus E2 proteinsINTERNATIONAL JOURNAL OF CANCER, Issue 10 2007Frank Stubenrauch Abstract Continuous expression of the human papillomavirus (HPV) oncoproteins E6 and E7 is required for the growth of cervical cancer cell lines. So far, only the overexpression of the wild type papillomavirus E2 protein has been shown to induce growth arrest in HPV18-positive HeLa cells by repressing E6/E7 transcription. Growth arrest by E2 requires the aminoterminal transcription activation domain in addition to the carboxyterminal DNA-binding domain. Several papillomaviruses such as the carcinogenic HPV31 express in addition to E2 an E8,E2C fusion protein in which the E8 domain, which is required for repression of replication and transcription, replaces the E2 activation domain. In this report, we demonstrate that the HPV31 E8,E2C protein is able to inhibit the growth of HeLa cells but not of HPV-negative C33A cervical cancer cells. Growth repression by E8,E2C correlates with repression of the endogenous HPV18 E6/E7 promoter and the reappearance of E6- and E7-regulated p53, pRb and p21 proteins, suggesting that E8,E2C inhibits growth by reactivating dormant tumor suppressor pathways. Growth inhibition requires an intact E8 repression domain in addition to the carboxyterminal E2C DNA binding domain. Chromatin immunoprecipitation experiments suggest that the E8 repression domain enhances binding to the HPV18 promoter sequence in vivo. In summary, our results demonstrate that the small E8 repression domain can functionally replace the large E2 transactivation domain for growth inhibition of HeLa cervical cancer cells. © 2007 Wiley-Liss, Inc. [source] Regulation of Arabidopsis thaliana 4-coumarate:coenzyme-A ligase-1 expression by artificial zinc finger chimerasPLANT BIOTECHNOLOGY JOURNAL, Issue 1 2006Juan Pablo Sánchez Summary The use of artificial zinc finger chimeras to manipulate the expression of a gene of interest is a promising approach because zinc finger proteins can be engineered to bind any given DNA sequence in the genome. We have previously shown that a zinc finger chimera with a VP16 activation domain can activate a reporter gene in transgenic Arabidopsis thaliana (Sánchez, J.P., Ullman, C., Moore, M., Choo, Y. and Chua, N.H. (2002) Regulation of gene expression in Arabidopsis thaliana by artificial zinc finger chimeras. Plant Cell Physiol. 43, 1465,1472). Here, we report the use of artificial zinc finger chimeras to specifically regulate the 4-coumarate:coenzyme-A ligase-1 (At4CL1) gene in A. thaliana. At4CL1 is a key enzyme in lignin biosynthesis and the down-regulation of At4CL1 can lead to a decrease in lignin content, which has a significant commercial value for the paper industry. To this end, we designed zinc finger chimeras containing either an activation or a repression domain, which bind specifically to the At4CL1 promoter region. Transgenic lines expressing a zinc finger chimera with the VP16 activation domain showed an increase in At4CL1 expression and enzyme activity. In contrast, transgenic lines expressing a chimera with the KOX (KRAB) repression domain displayed repression of At4CL1 expression and enzyme activity. The activation of At4CL1 expression produced an increase in lignin content, and transgenic plant stems showed ectopic lignin distribution. Repression of the At4CL1 gene resulted in reduced lignin content, and lignin distribution in transgenic stems was severely diminished. Our results confirm and extend previous studies of gene regulation using various artificial zinc finger chimeras in animal and plant systems, and show that this system can be used to up- and down-regulate the expression of an endogenous plant gene such as At4CL1. [source] Biological activity of RE-1 silencing transcription factor (REST) towards distinct transcriptional activatorsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2001Michael Lietz Abstract The zinc finger protein RE-1 silencing transcription factor (REST) is a transcriptional repressor that represses neuronal genes in non-neuronal tissues. We have analyzed the ability of REST and the REST mutants, REST,N and REST,C lacking either the N-terminal or C-terminal repression domains of REST, to inhibit transcription mediated by distinct transcriptional activator proteins. For this purpose we have designed an activator specific assay where transcription is activated as a result of only one distinct activation domain. In addition, binding sites for REST were inserted in the 5,-untranslated region or at a distant position downstream of the polyadenylation signal. The results show that REST or the REST mutants containing only one repression domain were able to block transcriptional activation mediated by the transcriptional activation domains derived from p53, AP2, Egr-1, and GAL4. Moreover, REST, as well as the REST mutants, blocked the activity of the phosphorylation-dependent activation domain of Elk1. However, the activity of the activation domain derived from cAMP response element binding protein 2 (CREB2), was not inhibited by REST, REST,N or REST,C, suggesting that REST is able to distinguish between distinct transcriptional activation domains. Additionally, the activator specific assay, together with a positive-dominant mutant of REST that activated instead of repressed transcription, was used in titration experiments to show that REST has transcriptional repression and no transcriptional activation properties when bound to the 5,-untranslated region of a gene. [source] Modulation of glucocorticoid receptor-interacting protein 1 (GRIP1) transactivation and co-activation activities through its C-terminal repression and self-association domainsFEBS JOURNAL, Issue 10 2006Pei-Yao Liu Glucocorticoid receptor-interacting protein 1 (GRIP1), a p160 family nuclear receptor co-activator, possesses at least two autonomous activation domains (AD1 and AD2) in the C-terminal region. AD1 activity appears to be mediated by CBP/p300, whereas AD2 activity is apparently mediated through co-activator-associated arginine methyltransferase 1 (CARM1). The mechanisms responsible for regulating the activities of AD1 and AD2 are not well understood. We provide evidence that the GRIP1 C-terminal region may be involved in regulating its own transactivation and nuclear receptor co-activation activities through primary self-association and a repression domain. We also compared the effects of the GRIP1 C terminus with those of other factors that functionally interact with the GRIP1 C terminus, such as CARM1. Based on our results, we propose a regulatory mechanism involving conformational changes to GRIP1 mediated through its intramolecular and intermolecular interactions, and through modulation of the effects of co-repressors on its repression domains. These are the first results to indicate that the structural components of GRIP1, especially those of the C terminus, might functionally modulate its putative transactivation activities and nuclear receptor co-activator functions. [source] Identification of a novel BTB-zinc finger transcriptional repressor, CIBZ, that interacts with CtBP corepressorGENES TO CELLS, Issue 9 2005Nobuhiro Sasai The transcriptional corepressor C-terminal binding protein (CtBP) is thought to be involved in development and oncogenesis, but the regulation of its corepressor activity is largely unknown. We show here that a novel BTB-zinc finger protein, CIBZ (CtBP-interacting BTB zinc finger protein; a mouse ortholog of rat ZENON that was recently identified as an e-box/dyad binding protein), redistributes CtBP to pericentromeric foci from a diffuse nuclear localization in interphase cells. CIBZ physically associates with CtBP via a conserved CtBP binding motif, PLDLR. When heterologously targeted to DNA, CIBZ represses transcription via two independent repression domains, an N-terminal BTB domain and a PLDLR motif-containing RD2 region, in a histone deacetylase-independent and -dependent manner, respectively. Mutation in the PLDLR motif abolishes the CIBZ-CtBP interaction and transcriptional repression activity of RD2, but does not affect the repression activity of the BTB domain. Furthermore, this PLDLR-mutated CIBZ cannot target CtBP to pericentromeric foci, although it is localized to the pericentromeric foci itself. These results suggest that at least one repression mechanism mediated by CIBZ is recruitment of the CtBP/HDAC complex to pericentromeric foci, and that CIBZ may regulate pericentromeric targeting of CtBP. [source] | |||||||||||||