微小RNA-22通过靶向甲基化CpG结合蛋白2调控干细胞向平滑肌细胞的分化。
MicroRNA-22 regulates smooth muscle cell differentiation from stem cells by targeting methyl CpG-binding protein 2.
作者信息
Zhao Hanqing, Wen Guanmei, Huang Yuan, Yu Xiaotian, Chen Qishan, Afzal Tayyab Adeel, Luong Le Anh, Zhu Jianhua, Ye Shu, Zhang Li, Xiao Qingzhong
机构信息
From the Centre for Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom (H.Z., G.W., Y.H., X.Y., Q.C., T.A.A., L.A.L., Y.S., Q.X.); and Department of Cardiology, the First Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang, China (Y.H., Q.C., J.Z., L.Z.).
出版信息
Arterioscler Thromb Vasc Biol. 2015 Apr;35(4):918-29. doi: 10.1161/ATVBAHA.114.305212. Epub 2015 Feb 26.
OBJECTIVE
In this study, we attempted to uncover the functional impact of microRNA-22 (miR-22) and its target gene in smooth muscle cell (SMC) differentiation and delineate the molecular mechanism involved.
APPROACH AND RESULTS
miR-22 was found to be significantly upregulated during SMC differentiation from embryonic stem cells and adventitia stem/progenitor cells. Enforced expression of miR-22 by its mimic, while knockdown of miR-22 by its antagomiR, promotes or inhibits SMC differentiation from embryonic stem cells and adventitia stem/progenitor cells, respectively. Expectedly, miR-22 overexpression in stem cells promoted SMC differentiation in vivo. Methyl CpG-binding protein 2 (MECP2) was predicted as one of the top targets of miR-22. Interestingly, the gene expression levels of MECP2 were significantly decreased during SMC differentiation, and MECP2 was dramatically decreased in miR-22 overexpressing cells but significantly increased when miR-22 was knockdown in the differentiating stem cells. Importantly, luciferase assay showed that miR-22 substantially inhibited wild-type, but not mutant MECP2-3' untranslated region-luciferase activity. In addition, modulation of MECP2 expression levels affects multiple SMC-specific gene expression in differentiated embryonic stem cells. Mechanistically, our data showed that MECP2 could transcriptionally repress SMC gene expression through modulating various SMC transcription factors, as well as several proven SMC differentiation regulators. Evidence also revealed that enrichment of H3K9 trimethylation around the promoter regions of the SMC differentiation regulators genes were significantly increased by MECP2 overexpression. Finally, miR-22 was upregulated by platelet-derived growth factor-BB and transforming growth factor-β through a transcriptional mechanism during SMC differentiation.
CONCLUSIONS
miR-22 plays an important role in SMC differentiation, and epigenetic regulation through MECP2 is required for miR-22 mediated SMC differentiation.
目的
在本研究中，我们试图揭示微小RNA-22（miR-22）及其靶基因在平滑肌细胞（SMC）分化中的功能影响，并阐明其中涉及的分子机制。
方法与结果
研究发现，在胚胎干细胞和外膜干/祖细胞向SMC分化的过程中，miR-22显著上调。分别用其模拟物增强miR-22的表达，以及用其反义寡核苷酸抑制miR-22的表达，可分别促进或抑制胚胎干细胞和外膜干/祖细胞向SMC的分化。不出所料，干细胞中miR-22的过表达在体内促进了SMC的分化。甲基化CpG结合蛋白2（MECP2）被预测为miR-22的主要靶标之一。有趣的是，在SMC分化过程中，MECP2的基因表达水平显著降低，在miR-22过表达的细胞中MECP2显著减少，而在分化的干细胞中抑制miR-22时MECP2显著增加。重要的是，荧光素酶报告基因检测表明，miR-22可显著抑制野生型而非突变型MECP2-3'非翻译区荧光素酶的活性。此外，调节MECP2的表达水平会影响分化的胚胎干细胞中多个SMC特异性基因的表达。从机制上讲，我们的数据表明，MECP2可通过调节各种SMC转录因子以及几种已证实的SMC分化调节因子来转录抑制SMC基因的表达。证据还显示，MECP2的过表达显著增加了SMC分化调节因子基因启动子区域周围H3K9三甲基化的富集。最后，在SMC分化过程中，血小板衍生生长因子-BB和转化生长因子-β通过转录机制上调了miR-22。
结论
miR-22在SMC分化中起重要作用，miR-22介导的SMC分化需要通过MECP2进行表观遗传调控。
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