Critical role of c-jun N-terminal protein kinase in promoting mitochondrial dysfunction and acute liver injury.
The mechanism by which c-Jun N-terminal protein kinase (JNK) promotes tissue injury is poorly understood. Thus we aimed at studying the roles of JNK and its phospho-target proteins in mouse models of acute liver injury. Young male mice were exposed to a single dose of CCl4 (50mg/kg, IP) and euthanized at different time points. Liver histology, blood alanine aminotransferase, and other enzyme activities were measured in CCl4-exposed mice without or with the highly-specific JNK inhibitors. Phosphoproteins were purified from control or CCl4-exposed mice and analyzed by differential mass-spectrometry followed by further characterizations of immunoprecipitation and activity measurements. JNK was activated within 1h while liver damage was maximal at 24h post-CCl4 injection. Markedly increased phosphorylation of many mitochondrial proteins was observed between 1 and 8h following CCl4 exposure. Pretreatment with the selective JNK inhibitor SU3327 or the mitochondria-targeted antioxidant mito-TEMPO markedly reduced the levels of p-JNK, mitochondrial phosphoproteins and liver damage in CCl4-exposed mice. Differential proteomic analysis identified many phosphorylated mitochondrial proteins involved in anti-oxidant defense, electron transfer, energy supply, fatty acid oxidation, etc. Aldehyde dehydrogenase, NADH-ubiquinone oxidoreductase, and α-ketoglutarate dehydrogenase were phosphorylated in CCl4-exposed mice but dephosphorylated after SU3327 pretreatment. Consistently, the suppressed activities of these enzymes were restored by SU3327 pretreatment in CCl4-exposed mice. These data provide a novel mechanism by which JNK, rapidly activated by CCl4, promotes mitochondrial dysfunction and acute hepatotoxicity through robust phosphorylation of numerous mitochondrial proteins.
Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892-9410, USA. Electronic address: sehwan.jang@upr.edu.
Sehwan
S
Jang
Biomarkers and Alternative Models Branch, Division of Systems Biology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079, USA. Electronic address: Lirong.Yu@fda.hhs.gov.
Li-Rong
LR
Yu
Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892-9410, USA. Electronic address: abdelmegeedm@mail.nih.gov.
Mohamed A
MA
Abdelmegeed
Biomarkers and Alternative Models Branch, Division of Systems Biology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079, USA. Electronic address: yuangao2000@gmail.com.
Yuan
Y
Gao
Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892-9410, USA. Electronic address: atrayee.liver@gmail.com.
Atrayee
A
Banerjee
Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892-9410, USA. Electronic address: bj.song@nih.gov.
Byoung-Joon
BJ
Song
D055371:Acute Lung Injury / Q000201:enzymology*; D000818:Animals; D019392:Cytochrome P-450 CYP2E1 / Q000502:physiology; D004789:Enzyme Activation; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology*; D008297:Male; D057507:Mice, 129 Strain; D008822:Mice, Transgenic; D008930:Mitochondria, Liver / Q000201:enzymology*; D024101:Mitochondrial Proteins / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051028:bcl-2-Associated X Protein / Q000378:metabolism
C494827:Bax protein, mouse; D024101:Mitochondrial Proteins; D051028:bcl-2-Associated X Protein; D019392:Cytochrome P-450 CYP2E1; D048031:JNK Mitogen-Activated Protein Kinases
Acute liver injury; Carbon tetrachloride; Differential proteomics; JNK; Mitochondria; Protein phosphorylation