title: miR-138 protects cardiomyocytes from hypoxia-induced apoptosis via MLK3/JNK/c-jun pathway.
abstract: Cardiomyocytes experience a series of complex endogenous regulatory mechanisms against apoptosis induced by chronic hypoxia. MicroRNAs are a class of endogenous small non-coding RNAs that regulate cellular pathophysiological processes. Recently, microRNA-138 (miR-138) has been found related to hypoxia, and beneficial for cell proliferation. Therefore, we intend to study the role of miR-138 in hypoxic cardiomyocytes and the main mechanism. Myocardial samples of patients with congenital heart disease (CHD) were collected to test miR-138 expression. Agomir or antagomir of miR-138 was transfected into H9C2 cells to investigate its effect on cell apoptosis. Higher miR-138 expression was observed in patients with cyanotic CHD, and its expression gradually increased with prolonged hypoxia time in H9C2 cells. Using MTT and LDH assays, cell growth was significantly greater in the agomir group than in the negative control (NC) group, while antagomir decreased cell survival. Dual luciferase reporter gene and Western-blot results confirmed MLK3 was a direct target of miR-138. It was found that miR-138 attenuated hypoxia-induced apoptosis using TUNEL, Hoechst staining and Annexin V-PE/7-AAD flow cytometry analysis. We further detected expression of apoptosis-related proteins. In the agomir group, the level of pro-apoptotic proteins such as cleaved-caspase-3, cleaved-PARP and Bad significantly reduced, while Bcl-2 and Bcl-2/Bax ratio increased. Opposite changes were observed in the antagomir group. Downstream targets of MLK3, JNK and c-jun, were also suppressed by miR-138. Our study demonstrates that up-regulation of miR-138 plays a protective role in myocardial adaptation to chronic hypoxia, which is mediated mainly by MLK3/JNK/c-jun signaling pathway.
authors.affiliation: Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Siyi
authors.initials: S
authors.lastname: He
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
authors.forename: Zhao
authors.initials: Z
authors.lastname: Jian
authors.forename: Jingwei
authors.initials: J
authors.lastname: Li
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhu
authors.forename: Zezhou
authors.initials: Z
authors.lastname: Feng
authors.forename: Yingbin
authors.initials: Y
authors.lastname: Xiao
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D002470:Cell Survival; D002648:Child; D003490:Cyanosis / Q000378:metabolism*; D006330:Heart Defects, Congenital / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology*; D051381:Rats; D015398:Signal Transduction; D055815:Young Adult; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11
chemical_list: D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020930:MAP Kinase Kinase Kinases; D035683:MicroRNAs; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11; C546110:MIRN138 microRNA, human
keywords: Apoptosis; Hypoxic adaptation; MLK3; miR-138