Abstract
More evidence is emerging of the roles long non-coding RNAs (lncRNAs) play as regulatory factors in a variety of biological processes, but the mechanisms underlying the function of lncRNAs in acute myocardial infarction (AMI) have not been explicitly delineated. The present study identified the lncRNA 2810403D21Rik/AK007586/Mirf (myocardial infarction-regulatory factor), that inhibited macroautophagy/autophagy by modulating Mir26a (microRNA 26a). Inhibition of Mir26a led to cardiac injury both in vitro and in vivo, whereas overexpression of Mir26a attenuated ischemic stress-induced cell death by activating autophagy through targeting Usp15 (ubiquitin specific peptidase 15). More importantly, 2810403D21Rik/Mirf acted as a competitive endogenous RNA (ceRNA) of Mir26a; forced expression of 2810403D21Rik/Mirf downregulated Mir26a to inhibit autophagy. In contrast, loss of 2810403D21Rik/Mirf resulted in upregulation of Mir26a to promote autophagy and alleviate cardiac injury, which in turn improved cardiac function in MI mice. This study identified a lncRNA 2810403D21Rik/Mirf that functions as an anti-autophagic molecule via ceRNA activity toward Mir26a. Our findings suggest that knockdown of 2810403D21Rik/Mirf might be a novel therapeutic approach for cardiac diseases associated with autophagy. Abbreviations: 3-MA: 3-methyladenine; AAV-9: adenovirus associated virus-9; agoMir26a: cholesterol-conjugated Mir26a mimic; AMI: acute myocardial infarction; AMO-26a: Mir26a inhibitor; ATG: autophagy related; BECN1: beclin 1; ceRNA: competitive endogenous RNAs; EF: ejection fraction; f-2810403D21Rik/Mirf: fragment encompassing the Mir26a binding site; FS: fraction shortening; GFP-mRFP: a plasmid expressing green fluorescent protein-monomeric red fluorescent protein; lncRNA: long non-coding RNA; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; Mirf: myocardial infarction-regulatory factor; miRNAs: microRNAs; NC: negative control; NMCMs: neonatal mice cardiomyocytes; shRNA: short hairpin RNA; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; Usp15: ubiquitin specific peptidase 15.