Silencing glycogen synthase kinase-3beta inhibits acetaminophen hepatotoxicity and attenuates JNK activation and loss of glutamate cysteine ligase and myeloid cell leukemia sequence 1.
Previously we demonstrated that c-Jun N-terminal kinase (JNK) plays a central role in acetaminophen (APAP)-induced liver injury. In the current work, we examined other possible signaling pathways that may also contribute to APAP hepatotoxicity. APAP treatment to mice caused glycogen synthase kinase-3beta (GSK-3beta) activation and translocation to mitochondria during the initial phase of APAP-induced liver injury ( approximately 1 h). The silencing of GSK-3beta, but not Akt-2 (protein kinase B) or glycogen synthase kinase-3alpha (GSK-3alpha), using antisense significantly protected mice from APAP-induced liver injury. The silencing of GSK-3beta affected several key pathways important in conferring protection against APAP-induced liver injury. APAP treatment was observed to promote the loss of glutamate cysteine ligase (GCL, rate-limiting enzyme in GSH synthesis) in liver. The silencing of GSK-3beta decreased the loss of hepatic GCL, and promoted greater GSH recovery in liver following APAP treatment. Silencing JNK1 and -2 also prevented the loss of GCL. APAP treatment also resulted in GSK-3beta translocation to mitochondria and the degradation of myeloid cell leukemia sequence 1 (Mcl-1) in mitochondrial membranes in liver. The silencing of GSK-3beta reduced Mcl-1 degradation caused by APAP treatment. The silencing of GSK-3beta also resulted in an inhibition of the early phase (0-2 h), and blunted the late phase (after 4 h) of JNK activation and translocation to mitochondria in liver following APAP treatment. Taken together our results suggest that activation of GSK-3beta is a key mediator of the initial phase of APAP-induced liver injury through modulating GCL and Mcl-1 degradation, as well as JNK activation in liver.
Shinohara
Mie
M
University of Southern California Research Center for Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California 90089-9121, USA.
Ybanez
Maria D
MD
Win
Sanda
S
Than
Tin Aung
TA
Jain
Shilpa
S
Gaarde
William A
WA
Han
Derick
D
Kaplowitz
Neil
N
D000082:Acetaminophen / Q000633:toxicity*; D018712:Analgesics, Non-Narcotic / Q000633:toxicity; D000818:Animals; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002478:Cells, Cultured; D056486:Chemical and Drug Induced Liver Injury / Q000378:metabolism* / Q000473:pathology; D003593:Cytoplasm / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D022781:Hepatocytes / Q000166:cytology / Q000201:enzymology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008930:Mitochondria, Liver / Q000201:enzymology / Q000473:pathology; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D051028:bcl-2-Associated X Protein / Q000378:metabolism
D018712:Analgesics, Non-Narcotic; C494827:Bax protein, mouse; D004791:Enzyme Inhibitors; C579094:Mcl1 protein, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D000082:Acetaminophen; D019328:Buthionine Sulfoximine; C494922:Akt2 protein, mouse; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases; D038362:Glycogen Synthase Kinase 3; C448021:glycogen synthase kinase 3 alpha; D005721:Glutamate-Cysteine Ligase