Overexpression of Rcan1-1L inhibits hypoxia-induced cell apoptosis through induction of mitophagy.
Mitophagy, a cellular process that selectively targets dysfunctional mitochondria for degradation, is currently a hot topic in research into the pathogenesis and treatment of many human diseases. Considering that hypoxia causes mitochondrial dysfunction, which results in cell death, we speculated that selective activation of mitophagy might promote cell survival under hypoxic conditions. In the present study, we introduced the Regulator of calcineurin 1-1L (Rcan1-1L) to initiate the mitophagy pathway and aimed to evaluate the effect of Rcan1-1L-induced mitophagy on cell survival under hypoxic conditions. Recombinant adenovirus vectors carrying Rcan1-1L were transfected into human umbilical vein endothelial cells and human adult cardiac myocytes. Using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide MTT assay and Trypan blue exclusion assay, Rcan1-1L overexpression was found to markedly reverse cell growth inhibition induced by hypoxia. Additionally, Rcan1-1L overexpression inhibited cell apoptosis under hypoxic conditions, as detected by annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) apoptosis assay. Meanwhile, the mitochondria-mediated cell apoptotic pathway was inhibited by Rcan1-1L. In contrast, knockdown of Rcan1-1L accelerated hypoxia-induced cell apoptosis. Moreover, Rcan1-1L overexpression significantly reduced mitochondrial mass, decreased depolarized mitochondria, and downregulated ATP and reactive oxygen species production. We further delineated that the loss of mitochondrial mass was due to the activation of mitophagy induced by Rcan1-1L. Rcan1-1L overexpression activated autophagy flux and promoted translocation of the specific mitophagy receptor Parkin into mitochondria from the cytosol, whereas inhibition of autophagy flux resulted in the accumulation of Parkin-loaded mitochondria. Finally, we demonstrated that mitochondrial permeability transition pore opening was significantly increased by Rcan1-1L overexpression, which suggested that Rcan1-1L might evoke mitophagy through regulating mitochondrial permeability transition pores. Taken together, we provide evidence that Rcan1-1L overexpression induces mitophagy, which in turn contributes to cell survival under hypoxic conditions, revealing for the first time that Rcan1-1L-induced mitophagy may be used for cardioprotection.
Department of Radiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China.
Lijun
L
Sun
Department of Radiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China.
Yuewen
Y
Hao
Department of Radiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China.
Rui
R
An
Department of Radiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China.
Haixun
H
Li
Department of Radiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China.
Cong
C
Xi
Department of Radiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China.
Guohong
G
Shen
D000255:Adenosine Triphosphate / Q000378:metabolism; D017209:Apoptosis; D015687:Cell Hypoxia; D002460:Cell Line; D002470:Cell Survival; D004268:DNA-Binding Proteins; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D063306:Mitophagy; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D009124:Muscle Proteins; D020033:Protein Isoforms; C108612:RCAN1 protein, human; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate
Rcan1-1L; apoptosis; hypoxia; mitochondria; mitophagy