Degradation of Keap1 activates BH3-only proteins Bim and PUMA during hepatocyte lipoapoptosis

S. C. Cazanave, X. Wang, H. Zhou, M. Rahmani, S. Grant, D. E. Durrant, C. D. Klaassen, M. Yamamoto, A. J. Sanyal

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)


Non-alcoholic steatohepatitis is characterized by hepatic steatosis, elevated levels of circulating free fatty acids (FFA) and hepatocyte lipoapoptosis. This lipoapoptosis requires increased JNK phosphorylation and activation of the pro-apoptotic BH3-only proteins Bim and PUMA. Kelch-like ECH-associated protein (Keap)-1 is a BTB/Kelch protein that can regulate the expression of Bcl-2 protein and control apoptotic cell death. Yet, the role of Keap1 in hepatocyte lipotoxicity is unclear. Here we demonstrate that Keap1 protein was rapidly degraded in hepatocytes, through autophagy in a p62-dependent manner, in response to the toxic saturated FFA palmitate, but not following incubation with the non-toxic FFA oleic acid. Stable knockdown of Keap1 expression, using shRNA technology, in hepatocarcinoma cell lines induced spontaneous cell toxicity that was associated with JNK1-dependent upregulation of Bim and PUMA protein levels. Also, Keap1 knockdown further sensitized hepatocytes to lipoapoptosis by palmitate. Likewise, primary hepatocytes isolated from liver-specific Keap1 -/- mice displayed higher Bim and PUMA protein levels and demonstrated increased sensitivity to palmitate-induced apoptosis than wild-type mouse hepatocytes. Finally, stable knockdown of Bim or PUMA expression prevented cell toxicity induced by loss of Keap1. These results implicate p62-dependent autophagic degradation of Keap1 by palmitate as a mechanism contributing to hepatocyte lipoapoptosis.

Original languageEnglish
Pages (from-to)1303-1312
Number of pages10
JournalCell Death and Differentiation
Issue number8
Publication statusPublished - 2014 Aug

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'Degradation of Keap1 activates BH3-only proteins Bim and PUMA during hepatocyte lipoapoptosis'. Together they form a unique fingerprint.

Cite this