Hopx expression defines a subset of multipotent hair follicle stem cells and a progenitor population primed to give rise to k6+ niche cells

Norifumi Takeda, Rajan Jain, Matthew R. LeBoeuf, Arun Padmanabhan, Qiaohong Wang, Li Li, Min Min Lu, Sarah E. Millar, Jonathan A. Epstein

Research output: Contribution to journalArticlepeer-review

60 Scopus citations

Abstract

The mammalian hair follicle relies on adult resident stem cells and their progeny to fuel and maintain hair growth throughout the life of an organism. The cyclical and initially synchronous nature of hair growth makes the hair follicle an ideal system with which to define homeostatic mechanisms of an adult stem cell population. Recently, we demonstrated that Hopx is a specific marker of intestinal stem cells. Here, we show that Hopx specifically labels long-lived hair follicle stem cells residing in the telogen basal bulge. Hopx+ cells contribute to all lineages of the mature hair follicle and to the interfollicular epidermis upon epidermal wounding. Unexpectedly, our analysis identifies a previously unappreciated progenitor population that resides in the lower hair bulb of anagen-phase follicles and expresses Hopx. These cells co-express Lgr5, do not express Shh and escape catagen-induced apoptosis. They ultimately differentiate into the cytokeratin 6-positive (K6) inner bulge cells in telogen, which regulate the quiescence of adjacent hair follicle stem cells. Although previous studies have suggested that K6+ cells arise from Lgr5-expressing lower outer root sheath cells in anagen, our studies indicate an alternative origin, and a novel role for Hopx-expressing lower hair bulb progenitor cells in contributing to stem cell homeostasis.

Original languageEnglish
Pages (from-to)1655-1664
Number of pages10
JournalDevelopment (Cambridge)
Volume140
Issue number8
DOIs
StatePublished - Apr 2013
Externally publishedYes

Keywords

  • Hopx
  • Mouse
  • Skin
  • Stem cell

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