北京大學(xué)心血管研究所汪南平教授領(lǐng)導(dǎo)的課題組,，近日在最新一期的PNAS雜志上發(fā)表文章,，首次證實(shí)血管的層流剪應(yīng)力調(diào)節(jié)了miRNA的表達(dá),，而其中一個(gè)miRNA分子—miR-19a，在cyclin D1表達(dá)的流動(dòng)調(diào)節(jié)及內(nèi)皮增殖中扮演了重要角色,。
如果血液的生物,、化學(xué)及物理學(xué)性質(zhì)發(fā)生了改變，血管內(nèi)皮通常能感知到,。血流所產(chǎn)生的摩擦力—剪應(yīng)力,，對內(nèi)皮的結(jié)構(gòu)和功能產(chǎn)生了多種影響。內(nèi)皮細(xì)胞應(yīng)對了機(jī)械力的變化,，引起信號網(wǎng)絡(luò)和細(xì)胞功能的調(diào)節(jié),。穩(wěn)態(tài)層流對內(nèi)皮細(xì)胞的抑制就是一個(gè)例子。至于內(nèi)皮細(xì)胞應(yīng)對血流機(jī)械性質(zhì)改變的分子機(jī)制,，以及如何經(jīng)歷結(jié)構(gòu)和功能的改變,，至今尚不清楚。越來越多的證據(jù)表明,，剪應(yīng)力通過調(diào)節(jié)內(nèi)皮細(xì)胞的基因表達(dá),，來施加生理影響。
眾所周知,，microRNA（miRNA）是～22個(gè)核苷酸的小RNA分子,，它們在轉(zhuǎn)錄后水平負(fù)調(diào)節(jié)了目的基因的表達(dá)。近期研究表明miRNA參與了血管發(fā)育和體內(nèi)平衡,，至于它和剪應(yīng)力有什么關(guān)聯(lián),，這也正是研究小組感興趣的。
汪南平教授的研究小組使用LC Sciences的microRNA芯片,，比較了人臍靜脈內(nèi)皮細(xì)胞（HUVEC）在有無層流剪切壓力（12 dyn/cm2,，12小時(shí)）下的miRNA表達(dá)譜。與對照細(xì)胞相比,，層流處理過的HUVEC在芯片上的569個(gè)miRNA中,，有35個(gè)miRNA顯著上調(diào)，而26個(gè)顯著下調(diào),。其中miR-19a在靜止?fàn)顟B(tài)下以高豐度表達(dá),，而暴露在剪應(yīng)力下12小時(shí)后，表達(dá)水平大幅提高,。
之后,，為了篩選miRNA所調(diào)節(jié)的靶點(diǎn)，他們制備了穩(wěn)定過表達(dá)miR-19a的細(xì)胞系,。多項(xiàng)分析表明,，miR-19a的穩(wěn)定轉(zhuǎn)染顯著減低了報(bào)告基因（此報(bào)告基因被cyclin D1基因的3’端非翻譯保守區(qū)所控制）的表達(dá)以及cyclin D1的蛋白水平，使細(xì)胞周期停滯在G1/S期。當(dāng)內(nèi)源miR-19a被抑制后,，這種抑制作用減弱,。
這項(xiàng)研究的主要發(fā)現(xiàn)在于，miR-19直接靶定了cyclin D1的表達(dá),。這已經(jīng)通過報(bào)告基因分析和Western blotting分析而證實(shí),。重要的是，他們發(fā)現(xiàn)了miR-19a的剪切誘導(dǎo)是抑制cyclin D1的表達(dá)水平所必需的,。過去觀察到層流剪應(yīng)力增加了cyclin D1轉(zhuǎn)錄本,，卻使細(xì)胞周期停滯，這項(xiàng)研究結(jié)果給出了一個(gè)可能的解釋,。
研究人員通過這一系列分析,，證實(shí)層流剪應(yīng)力調(diào)節(jié)了miRNA的表達(dá)，而miR-19a在cyclin D1表達(dá)的流動(dòng)調(diào)節(jié)及內(nèi)皮增殖中扮演了重要角色,。這些結(jié)果揭示出機(jī)械力如何調(diào)節(jié)內(nèi)皮基因表達(dá)的機(jī)制,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS January 27, 2010, doi: 10.1073/pnas.0914825107
Role of microRNA-23b in flow-regulation of Rb phosphorylation and endothelial cell growth
Kuei-Chun Wanga, Lana Xia Garmirea, Angela Younga, Phu Nguyena, Andrew Trinha, Shankar Subramaniama, Nanping Wangb, John YJ Shyyc, Yi-Shuan Lia,1, and Shu Chiena,1
aDepartment of Bioengineering and Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA 92093;
bKey Laboratory of Molecular Cardiovascular Science, Peking University Health Science Center, Beijing 100191, China; and
cDivision of Biomedical Sciences, University of California, Riverside, CA 92521
MicroRNAs (miRs) can regulate many cellular functions, but their roles in regulating responses of vascular endothelial cells (ECs) to mechanical stimuli remain unexplored. We hypothesize that the physiological responses of ECs are regulated by not only mRNA and protein signaling networks, but also expression of the corresponding miRs. EC growth arrest induced by pulsatile shear (PS) flow is an important feature for flow regulation of ECs. miR profiling showed that 21 miRs are differentially expressed (8 up- and 13 downregulated) in response to 24-h PS as compared to static condition (ST). The mRNA expression profile indicates EC growth arrest under 24-h PS. Analysis of differentially expressed miRs yielded 68 predicted mRNA targets that overlapped with results of microarray mRNA profiling. Functional analysis of miR profile indicates that the cell cycle network is highly regulated. The upregulation of miR-23b and miR-27b was found to correlate with the PS-induced EC growth arrest. Inhibition of miR-23b using antagomir-23b oligonucleotide (AM23b) reversed the PS-induced E2F1 reduction and retinoblastoma (Rb) hypophosphorylation and attenuated the PS-induced G1/G0 arrest. Antagomir AM27b regulated E2F1 expression, but did not affect Rb and growth arrest. Our findings indicate that PS suppresses EC proliferation through the regulation of miR-23b and provide insights into the role of miRs in mechanotransduction.
