Msi RNA-binding proteins control reserve intestinal stem cell quiescence

J Cell Biol. 2016 Nov 7;215(3):401-413. doi: 10.1083/jcb.201604119. Epub 2016 Oct 31.

Abstract

Regeneration of the intestinal epithelium is driven by multiple intestinal stem cell (ISC) types, including an active, radiosensitive Wnthigh ISC that fuels turnover during homeostasis and a reserve, radioresistant Wntlow/off ISC capable of generating active Wnthigh ISCs. We examined the role of the Msi family of oncoproteins in the ISC compartment. We demonstrated that Msi proteins are dispensable for normal homeostasis and self-renewal of the active ISC, despite their being highly expressed in these cells. In contrast, Msi proteins are required specifically for activation of reserve ISCs, where Msi activity is both necessary and sufficient to drive exit from quiescence and entry into the cell cycle. Ablation of Msi activity in reserve ISCs rendered the epithelium unable to regenerate in response to injury that ablates the active stem cell compartment. These findings delineate a molecular mechanism governing reserve ISC quiescence and demonstrate a necessity for the activity of this rare stem cell population in intestinal regeneration.

MeSH terms

  • Animals
  • Cell Lineage / radiation effects
  • Cell Proliferation / radiation effects
  • Epithelium / pathology
  • Epithelium / radiation effects
  • Gamma Rays
  • Homeostasis / radiation effects
  • Intestines / cytology*
  • Mice, Inbred C57BL
  • Nerve Tissue Proteins / metabolism*
  • RNA-Binding Proteins / metabolism*
  • Radiation Injuries / pathology
  • Resting Phase, Cell Cycle / radiation effects
  • S Phase / radiation effects
  • Stem Cells / cytology*
  • Stem Cells / metabolism*
  • Stem Cells / radiation effects
  • Up-Regulation / radiation effects
  • Wnt Signaling Pathway / radiation effects

Substances

  • Msi1h protein, mouse
  • Msi2h protein, mouse
  • Nerve Tissue Proteins
  • RNA-Binding Proteins