Promoter Sites (promoter + site)

Distribution by Scientific Domains

Selected Abstracts

Mucosal NOD2 expression and NF-,B activation in pediatric Crohn's disease

Laura Stronati PhD
Abstract Background: Recent advances in the pathogenesis of Crohn's disease (CD) have suggested that an aberrant innate immune response initiates the cascade of events leading to T-cell activation and to disease development. NOD2 protein, which is mainly expressed by innate immunity cells, appears to play a key role against bacteria by triggering a host defense response through the activation of the transcriptor factor NF-,B and a consequent proinflammatory cytokine production. The present study was aimed at investigating the expression and activity of NOD2, NF-,B, and of 2 proinflammatory cytokines, TNF, and IL-1,, in mucosal biopsies of CD affected children compared to healthy controls. Methods: In all, 22 children with active CD and 10 matched controls were entered in the study. mRNA and protein expressions were detected using reverse-transcriptase polymerase chain reaction (RT-PCR) and Western blot; NF-,B binding activity was assessed by electromobility gel shift assay (EMSA). Results: NOD2 and IL-1, mRNAs were upregulated in CD children. Protein levels of NOD2, TNF,, and nuclear NF-,B, as well as the binding activity of NF-,B to a consensus DNA sequence, were significantly increased in inflamed mucosa of patients as compared to controls. Moreover, NF-,B activity was strongly upregulated in patients also when bound to the NOD2 promoter site. No difference was seen between patients and controls when NF-,B binding activity was determined in the uninflamed tissue. Conclusions: This study suggests that altered mechanisms regulating NOD2 induction, NF-,B activation and cytokine production may contribute to dysregulate the innate immune response underlying pediatric CD. (Inflamm Bowel Dis 2007) [source]

CpG methylation at promoter site ,140 inactivates TGF,2 receptor gene in prostate cancer

CANCER, Issue 1 2005
Hong Zhao M.D.
Abstract BACKGROUND The action of transforming growth factor , (TGF-,) is mediated through type 1 (T,RI) and type 2 (T,RII) receptors. Prostate cancer cells are often resistant to TGF-, signaling due to loss of T,RII expression. The authors of the current study hypothesized that CpG methylation of the T,RII promoter at the Sp1 binding site ,140 mediates this loss of T,RII expression in prostate cancer. METHODS Sixty-seven prostate cancer (PC) samples, 8 benign prostatic hyperplasia (BPH) samples, and 4 prostate cancer cell lines (DUPro, LNCaP, ND-1 and PC-3) were analyzed for 1) T,RII mRNA expression by semiquantitative RT-PCR, 2) T,RII protein expression by immunohistochemistry, and 3) TGF,RII promoter methylation at CpG site ,140 by methylation specific PCR and bisulfite DNA sequencing. Prostate cancer cell lines were treated with the demethylating agent 5aza2,deoxycytidine to determine if T,RII gene expression could be increased by blocking promoter methylation. RESULTS mRNA and protein expression of T,RII was lower in the PC samples than in the BPH samples. CpG methylation at site ,140 was higher in PC than in BPH (P < 0.01). Promoter methylation was inversely correlated with T,RII mRNA expression in the PC and BPH samples (P < 0.0001). PC3, ND1, and DUPro T,RII mRNA expression increased following treatment of cells with 5-aza-2,-deoxycytidine. CONCLUSION CpG methylation of the T,RII promoter at CPG site ,140 leads to functional loss of the T,RII gene in prostate cancer. Treatment with 5-aza-2, deoxycytidine can restore gene expression. The current study results report the first association between prostate cancer and loss of the TGF- , signaling pathway by T,RII DNA promoter methylation. Cancer 2005;. 2005 American Cancer Society. [source]

Misregulation of gene expression in the redox-sensitive NF-,b-dependent limb outgrowth pathway by thalidomide

Jason M. Hansen
Abstract Thalidomide is known to induce oxidative stress, but mechanisms have not been described through which oxidative stress could contribute to thalidomide-induced terata. Oxidative stress modulates intracellular glutathione (GSH) and redox status and can perturb redox-sensitive processes, such as transcription factor activation and/or binding. Nuclear factor-kappa B (NF-,B), a redox-sensitive transcription factor involved in limb outgrowth, may be modulated by thalidomide-induced redox shifts. Thalidomide-resistant Sprague-Dawley rat embryos (gestation day [GD] 13) treated with thalidomide in utero showed no changes in GSH distribution in the limb but thalidomide-sensitive New Zealand White rabbit embryos (GD 12) showed selective GSH depletion in the limb bud progress zone (PZ). NF-,B and regulatory genes that initiate and maintain limb outgrowth and development, such as Twist and Fgf-10, are selectively expressed in the PZ. Green fluorescent protein (GFP) reporter vectors containing NF-,B binding promoter sites were transfected into both rat and rabbit limb bud cells (LBCs). Treatment with thalidomide caused a preferential decrease in GFP expression in rabbit LBCs but not in rat LBCs. N-acetylcysteine and ,-N-t-phenylbutyl nitrone (PBN), a free radical trapping agent, rescued GFP expression in thalidomide-treated cultures compared with cultures that received thalidomide only. In situ hybridization showed a preferential decrease in Twist, Fgf-8, and Fgf-10 expression after thalidomide treatment (400 mg/kg per day) in rabbit embryos. Expression in rat embryos was not affected. Intravenous cotreatment with PBN and thalidomide (gavage) in rabbits restored normal patterns and localization of Twist, Fgf-8, and Fgf-10 expression. These findings show that NF-,B binding is diminished due to selective thalidomide-induced redox changes in the rabbit, resulting in the significant attenuation of expression of genes necessary for limb outgrowth. 2002 Wiley-Liss, Inc. [source]

Long-term depression activates transcription of immediate early transcription factor genes: involvement of serum response factor/Elk-1

Antje Lindecke
Abstract Long-term depression (LTD) is one of the paradigms used in vivo or ex vivo for studying memory formation. In order to identify genes with potential relevance for memory formation we used mouse organotypic hippocampal slice cultures in which chemical LTD was induced by applications of 3,5-dihydroxyphenylglycine (DHPG). The induction of chemical LTD was robust, as monitored electrophysiologically. Gene expression analysis after chemical LTD induction was performed using cDNA microarrays containing >7000 probes. The DHPG-induced expression of immediate early genes (c-fos, junB, egr1 and nr4a1) was subsequently verified by TaqMan polymerase chain reaction. Bioinformatic analysis suggested a common regulator element [serum response factor (SRF)/Elk-1 binding sites] within the promoter region of these genes. Indeed, here we could show a DHPG-dependent binding of SRF at the SRF response element (SRE) site within the promoter region of c-fos and junB. However, SRF binding to egr1 promoter sites was constitutive. The phosphorylation of the ternary complex factor Elk-1 and its localization in the nucleus of hippocampal neurones after DHPG treatment was shown by immunofluorescence using a phosphospecific antibody. We suggest that LTD leads to SRF/Elk-1-regulated gene expression of immediate early transcription factors, which could in turn promote a second broader wave of gene expression. [source]

Mechanisms for activating bacterial RNA polymerase

Tamaswati Ghosh
Abstract Gene transcription is a fundamental cellular process carried out by RNA polymerase (RNAP) enzymes and is highly regulated through the action of gene regulatory complexes. Important mechanistic insights have been gained from structural studies on multisubunit RNAP from bacteria, yeast and archaea, although the initiation process that involves the conversion of the inactive transcription complex to an active one has yet to be fully understood. RNAPs are unambiguously closely related in structure and function across all kingdoms of life and have conserved mechanisms. In bacteria, sigma (,) factors direct RNAP to specific promoter sites and the RNAP/, holoenzyme can either form a stable closed complex that is incompetent for transcription (as in the case of ,54) or can spontaneously proceed to an open complex that is competent for transcription (as in the case of ,70). The conversion of the RNAP/,54 closed complex to an open complex requires ATP hydrolysis by enhancer-binding proteins, hence providing an ideal model system for studying the initiation process biochemically and structurally. In this review, we present recent structural studies of the two major bacterial RNAP holoenzymes and focus on mechanistic advances in the transcription initiation process via enhancer-binding proteins. [source]

Heregulin and forskolin-induced cyclin D3 expression in Schwann cells: Role of a CCAAT promoter element and CCAAT enhancer binding protein

GLIA, Issue 3 2004
Luis Fuentealba
Abstract Heregulin, a polypeptide growth factor, and forskolin, an adenylyl cyclase activator, synergistically stimulate expression of cyclin D3 and cell division in Schwann cells. Heregulin induces expression in Schwann cells of a luciferase reporter gene linked to the cyclin D3 promoter. Forskolin markedly augments reporter expression in the presence of heregulin. Deletion analysis identified several promoter sites that contribute to high-level reporter expression in heregulin- and forskolin-treated Schwann cells. A promoter fragment that contains 103 bp of 5,-flanking sequence produced significant reporter expression in heregulin- and forskolin-stimulated cells. Deletion of a consensus CCAAT site within this promoter fragment caused a nearly complete loss of reporter expression. Similar results were obtained when CCAAT site mutations were introduced into the promoter. Heregulin and forskolin increased steady-state levels of CCAAT/enhancer binding protein-, (C/EBP,) in Schwann cells. Mobility shift assays identified proteins in Schwann cell nuclear extracts that formed stable complexes with the cyclin D3 CCAAT promoter element and were disrupted by anti-C/EBP, antibody. Transfection of Schwann cells with C/EBP, cDNA increased cyclin D3 reporter expression. In contrast to these results, mutation of a cAMP response element in the cyclin D3 promoter had only a modest effect on heregulin- and forskolin-stimulated reporter expression. These findings demonstrate that C/EBP, plays a key role in the heregulin and cAMP-dependent regulation of cyclin D3 expression in Schwann cells. 2003 Wiley-Liss, Inc. [source]