Keratin expression provides novel insight into the morphogenesis and function of the companion layer in hair follicles

Li Hong Gu, Pierre A. Coulombe

Research output: Contribution to journalArticle

Abstract

Hair follicles cycle between stages of growth (anagen) and metabolic quiescence (telogen) throughout life. In mature follicles, transition from telogen back into anagen involves the activation, proliferation, and differentiation of epithelial stem cells located in the bulge, a specialization of the outer root sheath. Recent studies identified keratin 6a (K6a) transcripts as enriched in bulge epithelial stem cells in mouse skin. We used messenger RNA probes, antibodies, a LacZ reporter mouse model, and whole-mount staining assays to investigate the regulation of mK6a during mouse postnatal hair cycling, and compare it to mK75, a companion layer (Cl) marker. We find that mK75 regulation parallels that of inner root sheath (IRS) markers, with expression onset at anagen IIIa above the new hair bulb and subsequent spreading towards the bulge. Although also occurring in the Cl, mK6a expression begins at anagen IIIb in differentiating cells located proximal to the bulge, and subsequently spreads towards the hair bulb. mK6a and mK75 thus exhibit temporally distinct, and spatially opposed, expression patterns in the Cl during postnatal anagen. These findings provide novel insight into the morphogenesis and properties of the Cl, and raise the distinct possibility that it is an integral part of the IRS compartment.

Original languageEnglish (US)
Pages (from-to)1061-1073
Number of pages13
JournalJournal of Investigative Dermatology
Volume127
Issue number5
DOIs
StatePublished - May 2007

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Hair Follicle
Keratins
Stem cells
Morphogenesis
Hair
Keratin-6
RNA Probes
Stem Cells
Epithelial Cells
Assays
Skin
Chemical activation
Messenger RNA
Antibodies
Staining and Labeling
Growth

ASJC Scopus subject areas

  • Dermatology

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Keratin expression provides novel insight into the morphogenesis and function of the companion layer in hair follicles. / Gu, Li Hong; Coulombe, Pierre A.

In: Journal of Investigative Dermatology, Vol. 127, No. 5, 05.2007, p. 1061-1073.

Research output: Contribution to journalArticle

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