title: Regulator of calcineurin 1-1L protects cardiomyocytes against hypoxia-induced apoptosis via mitophagy.
abstract: Mitochondrial dysfunction induced by myocardial ischemia is the primary cause of cardiac cell death. Specific removal of damaged mitochondria through mitophagy may be beneficial for cardiomyocyte protection against ischemia. Regulator of calcineurin 1-1L (Rcan1-1L) has been implicated in mitophagy induction in neurons. However, whether or not Rcan1-1L can evoke mitophagy in cardiomyocytes during hypoxia remains unknown. This study aims to investigate the effect of Rcan1-1L overexpression on cardiomyocytes during hypoxia and the possible underlying mechanism. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that Rcan1-1L overexpression inhibited cell growth under normoxic conditions, whereas Rcan1-1L overexpression significantly reversed the growth inhibition induced by hypoxia. The results of terminal deoxynucleotidyl transferase biotin-dUTP nick end-labeling assay showed that cell apoptosis induced by hypoxia was markedly reduced by Rcan1-1L overexpression. In addition, Rcan1-1L overexpression inhibited the expression of the proapoptotic protein Bcl-2-associated death promoter and increased that of the antiapoptotic protein Bcl-2. Rcan1-1L overexpression opened the mitochondrial permeability transition pore and decreased mitochondrial mass. Meanwhile, the release of reactive oxygen species from mitochondria was suppressed by Rcan1-1L. Autophagy flow activation represented by mammalian target of rapamycin inhibition and microtubule-associated protein light chain 3 (LC3) upregulation was also demonstrated. Compared with endoplasmic reticulum and Golgi apparatus protein markers, the mitochondrial protein marker translocase of outer mitochondrial membranes 20 (TOM20) was downregulated by Rcan1-1L overexpression. Moreover, Rcan1-1L increased mitophagy receptor Parkin translocation into mitochondria from cytosol. Additionally, the effect of Rcan1-1L on cell growth, cell apoptosis and mitochondria mass was blocked by Parkin expression silencing. Overall, these data suggest that Rcan1-1L protects cardiomyocytes from hypoxia-induced apoptosis by inducing mitophagy partly through Parkin. This study provided novel insights into the prevention and treatment of ischemic heart disease.
authors.affiliation: Department of Cardiology, Henan Provincial People's Hospital, Zhengzhou, China.
authors.forename: Lijie
authors.initials: L
authors.lastname: Yan
authors.forename: Haitao
authors.initials: H
authors.lastname: Yang
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Li
authors.forename: Hongyan
authors.initials: H
authors.lastname: Duan
authors.forename: Jintao
authors.initials: J
authors.lastname: Wu
authors.forename: Peng
authors.initials: P
authors.lastname: Qian
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.forename: Shanling
authors.initials: S
authors.lastname: Wang
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D015153:Blotting, Western; D065095:Calcineurin Inhibitors / Q000494:pharmacology; D018929:Cell Culture Techniques; D015687:Cell Hypoxia / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D063306:Mitophagy / Q000187:drug effects* / Q000235:genetics; D009124:Muscle Proteins / Q000235:genetics / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D010957:Plasmids; D020033:Protein Isoforms; D017382:Reactive Oxygen Species / Q000378:metabolism; D014162:Transfection
chemical_list: D065095:Calcineurin Inhibitors; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009124:Muscle Proteins; D020033:Protein Isoforms; C108612:RCAN1 protein, human; D017382:Reactive Oxygen Species