全基因组分析揭示了肝脏 FXR 存在不对称的 IR-1 基序,并且与 LRH-1 存在协同作用。

Genome-wide interrogation of hepatic FXR reveals an asymmetric IR-1 motif and synergy with LRH-1.

机构信息

Department of Molecular Biology and Biochemistry, Institute for Genomics and Bioinformatics, University of California, Irvine, CA 92697, USA.

出版信息

Nucleic Acids Res. 2010 Oct;38(18):6007-17. doi: 10.1093/nar/gkq397. Epub 2010 May 18.

Abstract

We used mouse hepatic chromatin enriched with an FXR antibody and chromatin immunoprecipitation-sequencing (ChIP-seq) to evaluate FXR binding on a genome-wide scale. This identified 1656 FXR-binding sites and 10% were located within 2 kb of a transcription start site which is much higher than predicted by random occurrence. A motif search uncovered a canonical nuclear receptor IR-1 site, consistent with in vitro DNA-binding studies reported previously. A separate nuclear receptor half-site for monomeric receptors such as LRH-1 was co-enriched and FXR activation of four newly identified promoters was significantly augmented by an LRH-1 expression vector in a co-transfection assay. There were 1038 genes located within 20 kb of a peak and a gene set enrichment analysis showed that genes identified by our ChIP-seq analysis are highly correlated with genes activated by an FXR-VP16 adenovirus in primary mouse hepatocytes providing functional relevance to the genome-wide binding study. Gene Ontology analysis showed FXR-binding sites close to many genes in lipid, fatty acid and steroid metabolism. Other broad gene clusters related to metabolism, transport, signaling and glycolysis were also significantly enriched. Thus, FXR may have a much wider role in cellular metabolism than previously appreciated.

摘要

我们使用富含 FXR 抗体的小鼠肝染色质和染色质免疫沉淀测序 (ChIP-seq) 来评估 FXR 在全基因组范围内的结合情况。这鉴定出 1656 个 FXR 结合位点,其中 10%位于转录起始位点的 2 kb 内,这一比例远高于随机发生的预期。 motif 搜索揭示了一个典型的核受体 IR-1 位点,与之前报道的体外 DNA 结合研究一致。一个单独的核受体单体受体(如 LRH-1)的半位点也被富集,在共转染实验中,LRH-1 表达载体显著增强了四个新鉴定的启动子的 FXR 激活。在距离峰 20 kb 内有 1038 个基因,基因集富集分析表明,我们的 ChIP-seq 分析鉴定的基因与 FXR-VP16 腺病毒在原代小鼠肝细胞中激活的基因高度相关,为全基因组结合研究提供了功能相关性。GO 分析显示 FXR 结合位点靠近脂质、脂肪酸和类固醇代谢中的许多基因。其他与代谢、运输、信号和糖酵解相关的广泛基因簇也显著富集。因此,FXR 在细胞代谢中的作用可能比以前认为的广泛得多。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/89a1/2952856/5eeaa281c22d/gkq397f1.jpg

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