title: Forkhead box O (FOXO) 3 modulates hypoxia-induced autophagy through AMPK signalling pathway in cardiomyocytes.
abstract: Autophagy is promoted as a response to such environmental stress conditions as ATP depletion and excessive accumulation of reactive oxygen species (ROS). Multiple signalling pathways, including AMP-activated protein kinase (AMPK), are indicated to promote autophagy in ischaemic/hypoxic (I/R) heart. However, it's far more to clarify the orchestrated cross-talk between AMPK and other signalling pathways in the autophagy. In the present study, we investigated the autophagy induction by hypoxia in Rat H9C2 cardiomyocytes with LC3-EGFP reporter, EM and Western blot analysis. Then, we examined the promotion of forkhead box O (FOXO) 3, one member of FOXO transcriptional protein family, by hypoxia in Rat H9C2 cells and determined the mediation of FOXO 3 in the hypoxia-induced autophagy in H9C2 cells. In addition, we investigated the role of AMPK signalling in the FOXO3-mediated, hypoxia-induced autophagy in H9C2 cells. It was demonstrated that hypoxia induced significant autophagy in H9C2 cells, via promoting autophagic vesicles, inducing the conversion of LC3-I to LC3-II and up-regulating autophagy-related (ATG) markers. Moreover, FOXO3 was up-regulated by the hypoxia in H9C2 cells; and the knockdown of FOXO3 significantly reduced the hypoxia-induced autophagy. In addition, AMPK signalling was significantly promoted by hypoxia in H9C2 cells, and the chemical manipulation of AMPK exerted significant influence on the hypoxia-induced autophagy and on the FOXO3 level. In conclusion, FOXO3 regulated the hypoxia-induced autophagy in cardiomyocytes, and AMPK mediated the FOXO3 promotion during the autophagy induction by hypoxia, implying the key regulatory role of FOXO3 and AMPK signalling in the hypoxia-induced autophagy in cardiomyocytes.
authors.affiliation: Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China.
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Chi
authors.affiliation: Department of Cardiology, Baotou Fourth Hospital, Inner Mongolia Autonomous Region, Baotou 014030, China.
authors.forename: Conghong
authors.initials: C
authors.lastname: Shi
authors.affiliation: Department of Cardiac Surgery, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, China chjuneguo@163.com.
authors.forename: Chengjun
authors.initials: C
authors.lastname: Guo
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D001343:Autophagy; D015687:Cell Hypoxia; D002460:Cell Line; D000071316:Forkhead Box Protein O3 / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction
chemical_list: C499515:FOXO3 protein, rat; D000071316:Forkhead Box Protein O3; D055372:AMP-Activated Protein Kinases
keywords: AMP-activated protein kinase (AMPK); autophagy; cardiomyocytes; forkhead box O (FOXO) 3; hypoxia