Wang Feng, Yuan Yuxiang, Yang Pirong, Li Xia
The 7th Department of Internal Medicine (Department of Geriatric Cardiovascular and Cerebrovascular Diseases), Zaozhuang Hospital of Zaozhuang Mining Group, Zaozhuang, 277100, Shandong, China.
Department of Cardiology, Zoucheng People's Hospital, Zoucheng, 273500, Shandong, China.
Mol Cell Biochem. 2017 Jul;431(1-2):187-195. doi: 10.1007/s11010-017-2990-4. Epub 2017 Mar 10.
In this study, we tested the hypothesis that extracellular vesicles (EVs)-mediated transfer of miR-208a/b can exacerbate apoptosis of cardiomyocytes (CMs) induced by hypoxia/reoxygenation (H/R) injury by reducing the expression of the RNA-binding protein Quaking (QKI). EVs were isolated from culture medium of hypoxic H9c2 cells (EVs-H). In in vitro H9c2 cell model, the EVs-H could be taken up by normoxic CMs and exacerbated cell apoptosis induced by H/R injury. In addition, miR-208a and miR-208b were enriched in EVs-H. Suppression of miR-208a and miR-208b loading significantly suppressed the detrimental effect of EVs-H on H/R injury in H9c2 cells. Inhibition of endogenous miR-208a and miR-208b restored QKI5 and QKI6 after H/R treatment. Dual-luciferase assay confirmed direct bindings between miR-208a/b and QKI 3'UTR. Functionally, QKI5 overexpression significantly suppressed H/R-induced CM apoptosis and suppressed the enhancing effect of EVs-H on CM apoptosis. Therefore, we infer that EVs-mediated transfer of miR-208a/b can exaggerate H/R injury in CMs by reducing QKI expression. This represents a previously unrecognized pathway of H/R injury in CMs.
在本研究中，我们验证了以下假设：细胞外囊泡（EVs）介导的miR-208a/b转移可通过降低RNA结合蛋白震颤蛋白（QKI）的表达来加重缺氧/复氧（H/R）损伤诱导的心肌细胞（CMs）凋亡。从缺氧的H9c2细胞培养基中分离出细胞外囊泡（EVs-H）。在体外H9c2细胞模型中，EVs-H可被常氧CMs摄取，并加重H/R损伤诱导的细胞凋亡。此外，miR-208a和miR-208b在EVs-H中富集。抑制miR-208a和miR-208b的装载可显著抑制EVs-H对H9c2细胞H/R损伤的有害作用。抑制内源性miR-208a和miR-208b可在H/R处理后恢复QKI5和QKI6。双荧光素酶测定证实了miR-208a/b与QKI 3'UTR之间的直接结合。在功能上，QKI5过表达可显著抑制H/R诱导的CM凋亡，并抑制EVs-H对CM凋亡的增强作用。因此，我们推断EVs介导的miR-208a/b转移可通过降低QKI表达来加重CMs中的H/R损伤作用。这代表了CMs中H/R损伤一种先前未被认识的途径。
