title: JNK1-dependent PUMA expression contributes to hepatocyte lipoapoptosis.
abstract: Free fatty acids (FFA) induce hepatocyte lipoapoptosis by a c-Jun N-terminal kinase (JNK)-dependent mechanism. However, the cellular processes by which JNK engages the core apoptotic machinery during lipotoxicity, especially activation of BH3-only proteins, remain incompletely understood. Thus, our aim was to determine whether JNK mediates induction of BH3-only proteins during hepatocyte lipoapoptosis. The saturated FFA palmitate, but not the monounsaturated FFA oleate, induces an increase in PUMA mRNA and protein levels. Palmitate induction of PUMA was JNK1-dependent in primary murine hepatocytes. Palmitate-mediated PUMA expression was inhibited by a dominant negative c-Jun, and direct binding of a phosphorylated c-Jun containing the activator protein 1 complex to the PUMA promoter was identified by electrophoretic mobility shift assay and a chromatin immunoprecipitation assay. Short hairpin RNA-targeted knockdown of PUMA attenuated Bax activation, caspase 3/7 activity, and cell death. Similarly, the genetic deficiency of Puma rendered murine hepatocytes resistant to lipoapoptosis. PUMA expression was also increased in liver biopsy specimens from patients with non-alcoholic steatohepatitis as compared with patients with simple steatosis or controls. Collectively, the data implicate JNK1-dependent PUMA expression as a mechanism contributing to hepatocyte lipoapoptosis.
authors.affiliation: Miles and Shirley Fitterman Center for Digestive Diseases, Division of Gastroenterology and Hepatology, College of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Sophie C
authors.initials: SC
authors.lastname: Cazanave
authors.forename: Justin L
authors.initials: JL
authors.lastname: Mott
authors.forename: Nafisa A
authors.initials: NA
authors.lastname: Elmi
authors.forename: Steven F
authors.initials: SF
authors.lastname: Bronk
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Werneburg
authors.forename: Yuko
authors.initials: Y
authors.lastname: Akazawa
authors.forename: Alisan
authors.initials: A
authors.lastname: Kahraman
authors.forename: Sean P
authors.initials: SP
authors.lastname: Garrison
authors.forename: Gerard P
authors.initials: GP
authors.lastname: Zambetti
authors.forename: Michael R
authors.initials: MR
authors.lastname: Charlton
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Gores
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D005234:Fatty Liver / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression / Q000187:drug effects; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D048055:Mitogen-Activated Protein Kinase 8 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010168:Palmitates / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000873:Anthracenes; D051017:Apoptosis Regulatory Proteins; C438378:BBC3 protein, human; C488588:PUMA protein, mouse; D010168:Palmitates; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; C432165:pyrazolanthrone; D048055:Mitogen-Activated Protein Kinase 8