title: JNK interaction with Sab mediates ER stress induced inhibition of mitochondrial respiration and cell death.
abstract: Our aim was to better understand the mechanism and importance of sustained c-Jun N-terminal kinase (JNK) activation in endoplasmic reticulum (ER) stress and effects of ER stress on mitochondria by determining the role of mitochondrial JNK binding protein, Sab. Tunicamycin or brefeldin A induced a rapid and marked decline in basal mitochondrial respiration and reserve-capacity followed by delayed mitochondrial-mediated apoptosis. Knockdown of mitochondrial Sab prevented ER stress-induced sustained JNK activation, impaired respiration, and apoptosis, but did not alter the magnitude or time course of activation of ER stress pathways. P-JNK plus adenosine 5'-triphosphate (ATP) added to isolated liver mitochondria promoted superoxide production, which was amplified by addition of calcium and inhibited by a blocking peptide corresponding to the JNK binding site on Sab (KIM1). This peptide also blocked tunicamycin-induced inhibition of cellular respiration. In conclusion, ER stress triggers an interaction of JNK with mitochondrial Sab, which leads to impaired respiration and increased mitochondrial reactive oxygen species, sustaining JNK activation culminating in apoptosis.
authors.affiliation: Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California Research Center for Liver Diseases, University of Southern California, Los Angeles, CA 90089-9121, USA.
authors.forename: S
authors.initials: S
authors.lastname: Win
authors.affiliation: Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California Research Center for Liver Diseases, University of Southern California, Los Angeles, CA 90089-9121, USA.
authors.forename: T A
authors.initials: TA
authors.lastname: Than
authors.affiliation: 1] Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California Research Center for Liver Diseases, University of Southern California, Los Angeles, CA 90089-9121, USA [2] Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA [3] Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), Consejo Superior Investigaciones Cientificas (CSIC) and Liver Unit-Hospital Clinic and CIBEREHD, Barcelona, Spain.
authors.forename: J C
authors.initials: JC
authors.lastname: Fernandez-Checa
authors.affiliation: 1] Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California Research Center for Liver Diseases, University of Southern California, Los Angeles, CA 90089-9121, USA [2] Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
authors.forename: N
authors.initials: N
authors.lastname: Kaplowitz
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D019069:Cell Respiration; D002478:Cells, Cultured; D015536:Down-Regulation; D059865:Endoplasmic Reticulum Stress; D022781:Hepatocytes / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; C568472:Sab protein, mouse; D000255:Adenosine Triphosphate; D048031:JNK Mitogen-Activated Protein Kinases