TFIIIC Binding to Alu Elements Controls Gene Expression via Chromatin Looping and Histone Acetylation

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The Fibrillin-1 RGD Integrin Binding Site Regulates Gene Expression and Cell Function through microRNAs

Fibrillins are the major components of microfibrils in the extracellular matrix of elastic and non-elastic tissues. Fibrillin-1 contains one evolutionarily conserved RGD sequence that mediates cell–matrix interactions through cell-surface integrins. Here, we present a novel paradigm how extracellular fibrillin-1 controls cellular function through integrin-mediated microRNA regulation. Comparative mRNA studies by global microarray analysis identified growth factor activity, actin binding and integrin binding as the most important functional groups that are regulated upon fibrillin-1 binding to dermal fibroblasts. Many of these mRNAs are targets of miRNAs that were identified when RNA from the fibrillin-1-ligated fibroblasts was analyzed by a miRNA microarray. The expression profile was specific to fibrillin-1 since interaction with fibronectin displayed a partially distinct profile. The importance of selected miRNAs for the regulation of the identified mRNAs was suggested by bioinformatics prediction and the interactions between miRNAs and mRNAs were experimentally validated. Functionally, we show that miR-503 controls p-Smad2-dependent TGF-β signaling, and that miR-612 and miR-3185 are involved in the focal adhesion formation regulated by fibrillin-1. In conclusion, we demonstrate that fibrillin-1 interaction with fibroblasts regulates miRNA expression profiles which in turn control critical cell functions.     

转录因子FOXM1在卵巢癌细胞中的表达及其对侵袭转移能力的影响

目的:研究上皮性卵巢癌细胞中FOXM1的表达,探讨FOXM1与MMP9之间的相关性以及与卵巢癌细胞侵袭、转移的关系。方法:采用Real-time RT-PCR、Western blotting技术检测pcDNA3.1-FOXM1和FOXM1-siRNA分别转染卵巢癌细胞株HO-8910(低转移)和HO-8910PM(高转移)前后FOXM1的表达水平,用Transwell方法检测转染该序列后HO-8910和HO-8910PM细胞侵袭能力的改变,并用荧光素酶双报告基因分析技术检测FOXM1对MMP9的调控作用。结果:与对照组和空载组相比,转染了pcDNA3.1-FOXM1的HO-8910细胞FOXM1 mRNA、蛋白表达显著升高,而转染了FOXM1-siRNA的高转移细胞株HO-8910PM FOXM1 mRNA、蛋白表达显著降低(P0.05);相对于空载体组和空白组,pcDNA3.1-FOXM1转染组细胞的侵袭能力明显增强,而FOXM1-siRNA转染细胞的侵袭能力明显降低(P0.05);FOXM1参与对MMP9的转录调控作用(P0.05)。结论:FOXM1可能是一个潜在的治疗靶点,通过下调FOXM1的表达,从而抑制卵巢癌的浸袭和转移。     

转录因子XBP1S基因表达谱差异分析

目的 应用基因表达谱芯片技术了解XBP1S在肝细胞中可能上调或下调的基因,了解其可能的调节功能线索.方法 构建pcDNA3.1（-）-XBP1S真核表达载体,转染HepG2细胞,同时以空载体pcDNA3.1（-）处理相同细胞系作为对照.48 h后制备细胞裂解液,提取mRNA,应用基因表达谱芯片技术对差异表达mRNA进行检测和分析.结果 构建的表达载体经过限制性内切酶分析和DNA序列测定,证实准确无误,提取高质量的总mRNA并进行逆转录成为cDNA,进行基因表达谱芯片技术分析.经过差异基因表达谱的筛选,发现HepG2细胞转染XBP1S以后,有38个基因表达水平显著上调,30个基因表达水平显著下调.结论 成功构建XBP1S的真核表达载体pcDNA3.1（-）-XBP1S,运用基因表达谱芯片技术成功筛选了XBP1S转染细胞后的差异表达基因,这些差异表达基因包括细胞周期、蛋白质的翻译合成及运输、能量代谢、体内免疫调节、细胞凋亡及细胞内的信号转导等方面起重要作用及肿瘤发生相关的基因,为进一步阐明XBP1S可能存在的调控机制及XBP1S蛋白可能的生物学功能提供理论依据.     

运用染色质免疫沉淀技术筛选出AP-2α的靶基因GALK1

在后基因组时代,DNA-蛋白质的相互作用是研究基因表达调控的一个重要领域.与其他方法相比,染色质免疫沉淀技术 (chromatin immunoprecipitation assay, ChIP ) 是一种近来研究体内 DNA 与蛋白质相互作用的最好方法之一.本研究利用 ChIP 克隆方法, 找出了 AP-2α所调控的新的下游靶基因 GALK1,并应用 Luciferase assay和 RT-PCR 实验进行了初步的验证.这一新发现,有利于我们进一步研究转录因子AP-2α的功能.