Sirt3-mediated mitophagy protects tumor cells against apoptosis under hypoxia
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Aimin Qiao1,*, Kuansong Wang4,5,*, Yunsheng Yuan7,*, Yidi Guan2, Xingcong Ren3, Lanya Li2, Xisha Chen2, Feng Li2, Alex F. Chen8,9, Jianda Zhou6, Jin-Ming Yang3, Yan Cheng2
1Center for Bioresources and Drug Discovery and School of Bioscience and Biopharmaceutics, Guangdong Pharmaceutical University, Guangzhou 510006, China
2Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410008, China
3Department of Pharmacology, The Penn State Hershey Cancer Institute, The Pennsylvania State University College of Medicine and Milton S. Hershey Medical Center, Hershey, PA 17033, USA
4Department of Pathology, Xiangya Hospital, Central South University, Changsha 410008, China
5Department of Pathology, Basic Medical School, Central South University, Changsha 410008, China
6Department of Plastic Surgery, The Third Xiangya Hospital, Central South University, Changsha 410008, China
7Engineering Research Center of Cell and Therapeutic Antibody, Ministry of Education, School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China
8Center for Vascular and Translational Medicine, The College of Pharmacy, Central South University, Changsha 410013, China
9The Third Xiangya Hospital, Central South University, Changsha 410013, China
*These authors contributed equally to this work
Yan Cheng, email: email@example.com
Jin-Ming Yang, email: firstname.lastname@example.org
Jianda Zhou, email: email@example.com
Keywords: Sirt3, mitophagy, hypoxia, apoptosis, cancer cells
Received: March 04, 2016 Accepted: May 05, 2016 Published: May 30, 2016
Sirt3, a mitochondrial deacetylase, participates in the regulation of multiple cellular processes through its effect on protein acetylation. The objective of this study was to explore the role of Sirt3 in the mitochondrial autophagy (mitophagy), a process of the specific autophagic elimination of damaged mitochondria. We found that silencing of Sirt3 expression in human glioma cells by RNA interference blunted the hypoxia-induced the localization of LC3 on the mitochondria, and the degradation of mitochondria. These results suggest an important involvement of this protein deacetylase in the induction of mitophagy in cancer cells subjected to hypoxia. Further, we demonstrated that Sirt3 activated the hypoxia-induced mitophagy by increasing the interaction of VDAC1 with Parkin. In the cells subjected to hypoxia, inhibition of Sirt3-mediated mitophagy further decreased the mitochondrial membrane potential, and increased the accumulation of ROS that triggers the degradation of anti-apoptotic proteins Mcl-1 and survivin through the proteasomal pathway. Silencing of Sirt3 expression also promoted apoptosis, and enhanced the sensitivity of cancer cells to hypoxia. The regulatory role of Sirt3 in autophagy and apoptosis was also observed in human breast cancer cells. The results of the current study reveal Sirt3 as a novel regulator coupling mitophagy and apoptosis, two important cellular processes that determine cellular survival and death.
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