• Biomolecules & Therapeutics
• /
• v.17 no.1
• /
• pp.12-16
• /
• 2009

One of the WHSC1/MMSET/NSD2 variant RE-IIBP is a histone H3-K27 methyltransferase with transcriptional repression activity. Overexpression of RE-IIBP in various types of leukemia suggests it's role in leukemogenesis. Here we identify two proteins, KRAB zinc finger protein ZNF 350 and enolase-1 as RE-IIBP interacting proteins by yeast two-hybrid screening and confirmed direct interaction in vivo and in vitro. Both proteins have been known for their role in transcriptional repression. Reporter assays using transient transfection demonstrated that both ZNF 350 and enolase-1 proteins synergistically repressed transcription with RE-IIBP, respectively. These results indicate both proteins have roles in RE-IIBP mediated transcriptional repression by involving co-repressor complex.

• BMB Reports
• /
• v.52 no.2
• /
• pp.127-132
• /
• 2019

Cells must fine-tune their gene expression programs for optimal cellular activities in their natural growth conditions. Transcriptional memory, a unique transcriptional response, plays a pivotal role in faster reactivation of genes upon environmental changes, and is facilitated if genes were previously in an active state. Hyper-activation of gene expression by transcriptional memory is critical for cellular differentiation, development, and adaptation. TREM (Transcriptional REpression Memory), a distinct type of transcriptional memory, promoting hyper-repression of unnecessary genes, upon environmental changes has been recently reported. These two transcriptional responses may optimize specific gene expression patterns, in rapidly changing environments. Emerging evidence suggests that they are also critical for immune responses. In addition to memory B and T cells, innate immune cells are transcriptionally hyperactivated by restimulation, with the same or different pathogens known as trained immunity. In this review, we briefly summarize recent progress in chromatin-based regulation of transcriptional memory, and its potential role in immune responses.

• Archives of Pharmacal Research
• /
• v.25 no.2
• /
• pp.208-213
• /
• 2002

The human polyomavirus JC virus is the etiologic agent of progressive multifocal leukoencephalopathy (PML). As the JC virus early promoter directs cell-specific expression of the viral replication factor large T antigen, transcriptional regulation constitutes a major mechanism of glial tropism in PML. It has been demonstrated that SV4O or JC virus large T antigen interacts with p53 protein and regulates many viral and cellular genes. In this study we founts that p53 represses the JC virus early promoter in both glial and nonglial cells To identify the cis-regulatory elements responsible for p53-mediated repression, deletional and site-directed mutational analyses were performed . Deletion of the enhancer region diminished p53-mediated transcriptional repression. However, point mutations of several transcription factor binding sites in the basal promoter region did not produce any significant changes. In support of this observation, when the enhancer was fused to a heterologous promoter, p53 red reduced the promoter activity about three fold. These results indicate that the enhancer region is important for tole repression of JC virus transcription by p53. Furthermore, coexpression of JC virus T antigen with a p53 protein abolished p53-mediated repression of the JC virus early promoter in non-glial cells, but not in glial cells. This finding suggests that T antigen interacts with p53 and regulates JC virus transcription in a cell-specific manner.

• Animal cells and systems
• /
• v.1 no.4
• /
• pp.647-651
• /
• 1997

We have used a transient expression assay employing Drosophila S2 cells to study the transcriptional repression activity of a 27 amino acid residue-long repression domain FS1 which was generated by a frame-shift in a pair-rule gene, even-skipped of Drosophila melanogaster. In an attempt to define a minimal requirement for the repression activity, we constructed a series of truncation mutant forms of the FS1, fused to a heterologous GAL4 DNA-binding domain, and measured their activities. All of the mutant forms, including the GAL4-FS1 (5-23) which retains the smallest number (19) of amino acid residues of FS1, were found to repress an initiator, a minimal TATA-lacking promoter, in a GAL4-binding-site-dependent manner. These findings suggest that a 19 amino acid residue-long region, rich in proline and leucine residues, is a transcriptional repression domain and may interact with the general transcription machinery.

• Genomics & Informatics
• /
• v.1 no.2
• /
• pp.113-118
• /
• 2003

Among a number of antigens characterized in M leprae, an etiological agent of Leprosy, the 18 kDa antigen, is unique to M leprae. We have previously determined a sequence specific element in the 18 kDa gene of M leprae, which confers transcriptional repression. In this report, we have examined if the element could be applied to genes other than the 18 kDa gene of M leprae. To identify the roles of the regulatory sequence in heterologous promoter, we have constructed pB3 vector series, which contains BCG hsp65 promoter and the M leprae 18 kDa transcription repression responsive element in tandem using LacZ gene as a reporter gene. Cloning of hsp65 promoters of M bovis BCG or M smegmatis in front of LacZ gene resulted in normal $\beta$­galactosidase activity as expected. However, when the sequence element was placed between the promoter and the LacZ gene, $\beta$-galactosidase activity was reduced 10-fold less. Also we have examined with pB3(-) vector, that harbors the transcription repression responsive element in a reversed orientation, the $\beta$-galactosidase activity was found to be similar to pB3(+) vector. Thus, these results further confirm that M leprae 18 kDa transcription repression responsive element could regulate BCG hsp65 heterologous promoter and that the element could act as an operator for the transcription of mycobacteria.

• BMB Reports
• /
• v.45 no.10
• /
• pp.577-582
• /
• 2012

single-minded (sim) is a master regulatory gene that directs differentiation in the central nervous system during Drosophila embryogenesis. Recent identification of the mesectoderm enhancer (MSE) of sim has led to the hypothesis that two Snail (Sna)-binding sites in the MSE may repress sim expression in the presumptive mesoderm. We provide evidence here that three Sna-binding sites proximal to the sim promoter, but not those of the MSE, are responsible for the mesodermal repression of sim in vivo. Using transgenic embryos injected with lacZ transgenes, we showed that sim repression in the mesoderm requires the three promoter-proximal Sna-binding sites. These results suggest that Sna represses the mesectodermal expression of sim by directly repressing the nearby promoter, and not by quenching adjacent transcriptional activators in the MSE. These data also showed how the MSE, lacking the three proximal Sna-binding sites, reproduced the endogenous pattern of sim expression in transgenic embryos.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.3
• /
• pp.514-523
• /
• 2017

Carbon catabolite repression is a crucial regulation mechanism in microorganisms, but its characteristic in Rhizopus is still unclear. We extracted a carbon regulation gene, cre, that encoded a carbon catabolite repressor protein (CRE) from Rhizopus stolonifer TP-02, and studied the regulation of CRE by real-time qPCR. CRE responded to glucose in a certain range, where it could significantly regulate part of the cellulase genes (eg, bg, and cbh2) without cbh1. In the comparison of the response of cre and four cellulase genes to carboxymethylcellulose sodium and a simple carbon source (lactose), the effect of CRE was only related to the concentration of reducing sugars. By regulating the reducing sugars to range from 0.4% to 0.6%, a glucose-containing medium with lactose as the inducer could effectively induce cellulases without the repression of CRE. This regulation method could potentially reduce the cost of enzymes produced in industries and provide a possible solution to achieve the largescale synthesis of cellulases.

• Journal of Microbiology
• /
• v.34 no.1
• /
• pp.40-48
• /
• 1996

We have examined the chromatin structure of the HMRE/HSP82 and HMRa/HSP82 allels using three complementary approaches : DNase I chromating footprinting, micrococcal nuclease (MNase) nucleosome-protected ladder assay, and an in vivo E. coli dam methylase accessibility assay. The footprinting results indicate that the promoter and silencer sequences are assembled into nucleoprotein complexes which exhibit no detectable change in structure, despite a 70-fold range in expression levels. In addition, the promoter region of the HMRa/HSP82 allele is cleaved randomly by MNase in all cases, indicating the absence of anonical nucleosomes over this region irrespective of SIR4 or heat-shock. Finally, no discernible difference in the accessibility of the HMRE/HSP82 locus to dam methylase in SIR4 vs. sir4 cells was seenm which again suggests that the chromatin structure of HMRE/HSP82 allele is identical regardless of SIR4. Altogether, our results indicate that in contrast to other observations of the silent mating-type loci, no discernible structural alteration is detected at either HMR/HSP82 allele regardless of SIR genetic background or transcriptional state of the gene.

• Development and Reproduction
• /
• v.21 no.4
• /
• pp.449-456
• /
• 2017

The germline stem cells of the Drosophila ovary continuously produce eggs throughout the life-span. Intricate regulation of stemness and differentiation is critical to this continuous production. The translational regulator Nos is an intrinsic factor that is required for maintenance of stemness in germline stem cells. Nos expression is reduced in differentiating cells at the post-transcriptional level by diverse translational regulators. However, molecular mechanisms underlying Nos repression are not completely understood. Through three distinct protein-protein interaction experiments, we identified specific molecular interactions between translational regulators involved in Nos repression. Our findings suggest a model in which protein complexes assemble on the 3' untranslated region of Nos mRNA in order to regulate Nos expression at the post-transcriptional level.

• Journal of Microbiology
• /
• v.34 no.1
• /
• pp.30-36
• /
• 1996

We have exmained the re-establishment of HIMRE mediated silencing function on the transcriptional activity of yeast heast shock gene HSP82. To test whether the onset of SIR repression can occur in growing cells in the rpesence of a potent inhibitor of DNA replication, HMRa/HSP82 strains with SIR4- and SIR4S$^{+}$ genetic backgrounds were arrested in S phase by incubation of a culture in 200 mM hydroxyurea for 120 min. It was clear that following a 20 minute heat shock, silencing of the HMRa/HSP82 allele in cells pretreated with hydroxyurea does occur in a SIR4-dependen fashion, even though the kinetics of repression appears to be substantially delayed. We also have tested whether re- establishement of silencing at the HMR/hsp82 locus can occur in G1-arrested cells. Cell cycle arrest at G1 phase was achieved by treatment of early log a cell cultures with .alpha.-factor mating pheromone, which induces G1 arrest. The result suggests that passage through S phase (and therefore DNA replication) is nor required for re-establishing silencer-mediated repression at the HMNRa/HSP82 locus. Finally, to test whether de nono protein synthesis is required for re-establishment of silencer-mediated repression, cells were pretreated with cycloheximide (500 /.mu.g/ml) 120 min. It was apparent that inhibiting protein synthesis delays, but does not prevent, re-establishment of silencer-mediated repression. Altogether, these results indicate that re-establishment of silencer-mediated repression is not dependent on the DNA replication and has no requirement for protein synthesis.s.