title: Calpain 2-mediated autophagy defect increases susceptibility of fatty livers to ischemia-reperfusion injury.
abstract: Hepatic steatosis is associated with significant morbidity and mortality after liver resection and transplantation. This study focuses on the role of autophagy in regulating sensitivity of fatty livers to ischemia and reperfusion (I/R) injury. Quantitative immunohistochemistry conducted on human liver allograft biopsies showed that, the reduction of autophagy markers LC3 and Beclin-1 at 1 h after reperfusion, was correlated with hepatic steatosis and poor survival of liver transplant recipients. In animal studies, western blotting and confocal imaging analysis associated the increase in sensitivity to I/R injury with low autophagy activity in fatty livers. Screening of autophagy-related proteins showed that Atg3 and Atg7 expression levels were marked decreased, whereas calpain 2 expression was upregulated during I/R in fatty livers. Calpain 2 inhibition or knockdown enhanced autophagy and suppressed cell death. Further point mutation experiments revealed that calpain 2 cleaved Atg3 and Atg7 at Atg3Δ92-97 and Atg7Δ344-349, respectively. In vivo and in vitro overexpression of Atg3 or Atg7 enhanced autophagy and suppressed cell death after I/R in fatty livers. Collectively, calpain 2-mediated degradation of Atg3 and Atg7 in fatty livers increases their sensitivity to I/R injury. Increasing autophagy may ameliorate fatty liver damage and represent a valuable method to expand the liver donor pool.
authors.affiliation: Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Biotherapy Department, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: W
authors.initials: W
authors.lastname: Deng
authors.affiliation: Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: S
authors.initials: S
authors.lastname: Fu
authors.affiliation: Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: M
authors.initials: M
authors.lastname: Chen
authors.affiliation: Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: W
authors.initials: W
authors.lastname: Ju
authors.affiliation: Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: D
authors.initials: D
authors.lastname: Wang
authors.affiliation: Organ Transplant Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: X
authors.initials: X
authors.lastname: He
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000633:toxicity; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D000071193:Autophagy-Related Protein 7 / Q000235:genetics / Q000378:metabolism; D000071183:Autophagy-Related Proteins / Q000235:genetics / Q000378:metabolism; D000071186:Beclin-1 / Q000378:metabolism; D002154:Calpain / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D016207:Cytokines / Q000032:analysis; D005234:Fatty Liver / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008099:Liver / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D017354:Point Mutation; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000071183:Autophagy-Related Proteins; D000071186:Beclin-1; D016207:Cytokines; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; C025946:3-methyladenine; D044763:Ubiquitin-Conjugating Enzymes; D002154:Calpain; D000071193:Autophagy-Related Protein 7; C455621:ATG3 protein, human; D000225:Adenine