title: Calcineurin suppresses AMPK-dependent cytoprotective autophagy in cardiomyocytes under oxidative stress.
abstract: Calcineurin signalling plays a critical role in the pathogenesis of many cardiovascular diseases. Calcineurin has been proven to affect a series of signalling pathways and to exert a proapoptotic effect in cardiomyocytes. However, whether it is able to regulate autophagy remains largely unknown. Here, we report that prolonged oxidative stress-induced activation of calcineurin contributes to the attenuation of adaptive AMP-activated protein kinase (AMPK) signalling and inhibits autophagy in cardiomyocytes. Primary cardiomyocytes exhibited rapid formation of autophagosomes, microtubule-associated protein 1 light chain 3 (LC3) expression and phosphorylation of AMPK in response to hydrogen peroxide (H₂O₂) treatment. However, prolonged (12 h) H₂O₂ treatment attenuated these effects and was accompanied by a significant increase in calcineurin activity and apoptosis. Inhibition of calcineurin by FK506 restored AMPK function and LC3 expression, and decreased the extent of apoptosis caused by prolonged oxidative stress. In contrast, overexpression of the constitutively active form of calcineurin markedly attenuated the increase in LC3 induced by short-term (3 h) H₂O₂ treatment and sensitised cells to apoptosis. In addition, FK506 failed to induce autophagy and alleviate apoptosis in cardiomyocytes expressing a kinase-dead K45R AMPK mutant. Furthermore, inhibition of autophagy by 3-methylanine (3-MA) or by knockdown of the essential autophagy-related gene ATG7 abrogated the protective effect of FK506. These findings suggest a novel role of calcineurin in suppressing adaptive autophagy during oxidative stress by downregulating the AMPK signalling pathway. The results also provide insight into how altered calcineurin and autophagic signalling is integrated to control cell survival during oxidative stress and may guide strategies to prevent cardiac oxidative damage.
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: H
authors.initials: H
authors.lastname: He
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: L
authors.initials: L
authors.lastname: Lv
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: H
authors.initials: H
authors.lastname: Liang
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: B
authors.initials: B
authors.lastname: Leng
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: D
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institute of Clinical Pharmacy, The Second Affiliated Hospital, Harbin Medical University, Harbin, Heilongjiang 150081, People's Republic of China.
authors.forename: Z
authors.initials: Z
authors.lastname: Du
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: S
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: Y
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Pharmacology (State-Province Key Laboratories of Biomedicine- Pharmaceutics of China, Key Laboratory of Cardiovascular Research, Ministry of Education), Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: H
authors.initials: H
authors.lastname: Shan
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D001343:Autophagy; D019703:Calcineurin / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D015536:Down-Regulation; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000201:enzymology*; D018384:Oxidative Stress; D051381:Rats; D015398:Signal Transduction
chemical_list: D055372:AMP-Activated Protein Kinases; D019703:Calcineurin; D008869:Microtubule-Associated Proteins; C526109:Anxa3 protein, rat