Intracellular XBP1-IL-24 axis dismantles cytotoxic unfolded protein response in the liver

Cell Death Dis. 2020 Jan 6;11(1):17. doi: 10.1038/s41419-019-2209-6.

Abstract

Endoplasmic reticulum (ER) stress-associated cell death is prevalent in various liver diseases. However, the determinant mechanism how hepatocytes survive unresolved stress was still unclear. Interleukin-24 (IL-24) was previously found to promote ER stress-mediated cell death, and yet its expression and function in the liver remained elusive. Here we identified an antiapoptotic role of IL-24, which transiently accumulated within ER-stressed hepatocytes in a X-box binding protein 1 (XBP1)-dependent manner. Disruption of IL-24 increased cell death in the CCL4- or APAP-challenged mouse liver or Tm-treated hepatocytes. In contrast, pharmaceutical blockade of eukaryotic initiation factor 2α (eIF2α) or genetical ablation of C/EBP homologous protein (CHOP) restored hepatocyte function in the absence of IL-24. In a clinical setting, patients with acute liver failure manifested a profound decrease of hepatic IL-24 expression, which was associated with disease progression. In conclusion, intrinsic hepatocyte IL-24 maintains ER homeostasis by restricting the eIF2α-CHOP pathway-mediated stress signal, which might be exploited as a bio-index for prognosis or therapeutic intervention in patients with liver injury.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Endoplasmic Reticulum Stress
  • Eukaryotic Initiation Factor-2
  • Hepatocytes / metabolism
  • Hepatocytes / pathology
  • Homeostasis
  • Interleukins / deficiency
  • Interleukins / metabolism*
  • Intracellular Space / metabolism*
  • Liver / injuries
  • Liver / metabolism*
  • Liver / pathology*
  • Mice, Inbred C57BL
  • Models, Biological
  • Signal Transduction*
  • Transcription Factor CHOP / metabolism
  • Unfolded Protein Response*
  • X-Box Binding Protein 1 / metabolism*
  • eIF-2 Kinase / metabolism

Substances

  • Eukaryotic Initiation Factor-2
  • Interleukins
  • X-Box Binding Protein 1
  • interleukin-24
  • Transcription Factor CHOP
  • PERK kinase
  • eIF-2 Kinase