TAK1 regulates SCF expression to modulate PKBα activity that protects keratinocytes from ROS-induced apoptosis

Cell Death Differ. 2011 Jul;18(7):1120-9. doi: 10.1038/cdd.2010.182. Epub 2011 Jan 14.

Abstract

Dysregulated reactive oxygen species (ROS) generation contributes to many human pathologies, including cancer and diabetes. During normal wound repair, inflammation-induced ROS production must be tightly controlled, but the mechanisms reining their generation remain unclear. Herein, we show that transforming growth factor β-activated kinase 1 (TAK1) directly regulates stem cell factor (SCF) expression, which activates the protein kinase B (PKB)α pro-survival pathway in a cell-autonomous manner to protect keratinocytes from ROS-mediated cell death. TAK1 is a pivotal inflammatory mediator whose expression was transiently elevated during wound healing, paralleling the ROS production profile. TAK1 deficiency in keratinocytes led to increased apoptosis in response to anoikis and TNF-α treatment and was associated with elevated ROS level as analyzed by FACS. Using organotypic skin co-culture and comparative growth factor array analysis, we revealed a cell-autonomous mechanism that involved the SCF/c-Kit/PKBα signaling cascade. Ectopic expression of TAK1 or treatment with exogenous recombinant SCF restored the increased ROS production and apoptotic cell death in TAK1-deficient keratinocytes. Conversely, normal keratinocytes treated with various inhibitors targeting the SCF/c-Kit/PKBα pathway exhibited increased ROS production and TNF-α- or anoikis-induced apoptosis. Our study reveals a novel anti-apoptotic role for SCF in keratinocytes and identifies TAK1 as a novel player uniting inflammation and ROS regulation in skin redox biology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis*
  • Cells, Cultured
  • Coculture Techniques
  • Humans
  • Keratinocytes / metabolism*
  • MAP Kinase Kinase Kinases / genetics
  • MAP Kinase Kinase Kinases / metabolism*
  • MAP Kinase Kinase Kinases / physiology
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Proto-Oncogene Proteins c-kit / antagonists & inhibitors
  • Proto-Oncogene Proteins c-kit / metabolism
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Reactive Oxygen Species / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / pharmacology
  • Signal Transduction
  • Stem Cell Factor / antagonists & inhibitors
  • Stem Cell Factor / genetics
  • Stem Cell Factor / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • RNA, Small Interfering
  • Reactive Oxygen Species
  • Recombinant Proteins
  • Stem Cell Factor
  • Tumor Necrosis Factor-alpha
  • Proto-Oncogene Proteins c-kit
  • Proto-Oncogene Proteins c-akt
  • MAP Kinase Kinase Kinases
  • MAP kinase kinase kinase 7