Protein kinase C (PKC) participates in acetaminophen hepatotoxicity through c-jun-N-terminal kinase (JNK)-dependent and -independent signaling pathways

Authors

  • Behnam Saberi,

    1. University of Southern California Research Center for Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, CA
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    • These authors contributed equally to this work.

  • Maria D. Ybanez,

    1. University of Southern California Research Center for Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, CA
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    • These authors contributed equally to this work.

  • Heather S. Johnson,

    1. University of Southern California Research Center for Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, CA
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  • William A. Gaarde,

    1. Isis Pharmaceuticals, Carlsbad, CA
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  • Derick Han,

    1. Department of Biopharmaceutical Sciences, School of Pharmacy, Keck Graduate Institute, Claremont, CA
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  • Neil Kaplowitz

    Corresponding author
    1. University of Southern California Research Center for Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, CA
    • Address reprint requests to: Neil Kaplowitz, USC Research Center for Liver Diseases, Keck School of Medicine, University of Southern California, 2011 Zonal Ave., HMR 101, Los Angeles, CA 90089-9121. E-mail: kaplowit@usc.edu; fax: 323-442-5425.

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  • See Editorial on Page 1229

    This work was supported by NIH grants DK067215 (to N.K.), AA016911 (to D.H.) and the USC Research Center for Liver Diseases (P30 DK048522) cell culture, cell, and tissue imaging (S10 RR022508) and analytical/metabolic/instrumentation cores.

  • Potential conflict of interest: Dr. Kaplowitz consults for GlaxoSmithKline, Pfizer, Merck, Novartis, Bristol-Myers Squibb, Johnson & Johnson, Hepregen, Daiichi Sankyo, Isis, Enanta, Takeda, Otsuka, Roche, and Sanofi-Aventis. Dr. Gaarde owns stock in Isis.

Abstract

This study examines the role of protein kinase C (PKC) and AMP-activated kinase (AMPK) in acetaminophen (APAP) hepatotoxicity. Treatment of primary mouse hepatocytes with broad-spectrum PKC inhibitors (Ro-31-8245, Go6983), protected against APAP cytotoxicity despite sustained c-jun-N-terminal kinase (JNK) activation. Broad-spectrum PKC inhibitor treatment enhanced p-AMPK levels and AMPK regulated survival-energy pathways including autophagy. AMPK inhibition by compound C or activation using an AMPK activator oppositely modulated APAP cytotoxicity, suggesting that p-AMPK and AMPK regulated energy survival pathways, particularly autophagy, play a critical role in APAP cytotoxicity. Ro-31-8245 treatment in mice up-regulated p-AMPK levels, increased autophagy (i.e., increased LC3-II formation, p62 degradation), and protected against APAP-induced liver injury, even in the presence of sustained JNK activation and translocation to mitochondria. In contrast, treatment of hepatocytes with a classical PKC inhibitor (Go6976) protected against APAP by inhibiting JNK activation. Knockdown of PKC-α using antisense (ASO) in mice also protected against APAP-induced liver injury by inhibiting JNK activation. APAP treatment resulted in PKC-α translocation to mitochondria and phosphorylation of mitochondrial PKC substrates. JNK 1 and 2 silencing in vivo decreased APAP-induced PKC-α translocation to mitochondria, suggesting PKC-α and JNK interplay in a feed-forward mechanism to mediate APAP-induced liver injury. Conclusion: PKC-α and other PKC(s) regulate death (JNK) and survival (AMPK) proteins, to modulate APAP-induced liver injury. (Hepatology 2014;59:1543-1554)

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