Rictor/mTORC2 deficiency enhances keratinocyte stress tolerance via mitohormesis

Cell Death Differ. 2017 Apr;24(4):731-746. doi: 10.1038/cdd.2017.8. Epub 2017 Feb 17.

Abstract

How metabolic pathways required for epidermal tissue growth and remodeling influence the ability of keratinocytes to survive stressful conditions is still largely unknown. The mechanistic target of rapamycin complex 2 (mTORC2) regulates growth and metabolism of several tissues, but its functions in epidermal cells are poorly defined. Rictor is an adaptor protein essential for mTORC2 activity. To explore the roles of mTORC2 in the epidermis, we have conditionally deleted rictor in mice via K14-Cre-mediated homologous recombination and found that its deficiency causes moderate tissue hypoplasia, reduced keratinocyte proliferation and attenuated hyperplastic response to TPA. Noteworthy, rictor-deficient keratinocytes displayed increased lifespan, protection from senescence, and enhanced tolerance to cellular stressors such as growth factors deprivation, epirubicin and X-ray in vitro and radioresistance in vivo. Rictor-deficient keratinocytes exhibited changes in global gene expression profiles consistent with metabolic alterations and enhanced stress tolerance, a shift in cell catabolic processes from glycids and lipids to glutamine consumption and increased production of mitochondrial reactive oxygen species (ROS). Mechanistically, the resiliency of rictor-deficient epidermal cells relies on these ROS increases, indicating stress resistance via mitohormesis. Thus, our findings reveal a new link between metabolic changes and stress adaptation of keratinocytes centered on mTORC2 activity, with potential implications in skin aging and therapeutic resistance of epithelial tumors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcysteine / pharmacology
  • Animals
  • Apoptosis / drug effects
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • Cellular Senescence / drug effects
  • Cellular Senescence / radiation effects
  • Epirubicin / toxicity
  • Glutamic Acid / metabolism
  • Hyperplasia
  • Keratin-14 / genetics
  • Keratinocytes / cytology
  • Keratinocytes / drug effects
  • Keratinocytes / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Radiation Tolerance / radiation effects
  • Rapamycin-Insensitive Companion of mTOR Protein / antagonists & inhibitors
  • Rapamycin-Insensitive Companion of mTOR Protein / deficiency
  • Rapamycin-Insensitive Companion of mTOR Protein / genetics*
  • Reactive Oxygen Species / metabolism
  • Skin / drug effects
  • Skin / metabolism
  • Skin / pathology
  • Tetradecanoylphorbol Acetate / analogs & derivatives
  • Tetradecanoylphorbol Acetate / pharmacology
  • Transcriptome / drug effects
  • Transcriptome / radiation effects
  • X-Rays

Substances

  • 12-O-tetradecanoylphorbol-1,3-acetate
  • Keratin-14
  • Rapamycin-Insensitive Companion of mTOR Protein
  • Reactive Oxygen Species
  • rictor protein, mouse
  • Glutamic Acid
  • Epirubicin
  • Tetradecanoylphorbol Acetate
  • Acetylcysteine