TY - JOUR
T1 - Keratin expression provides novel insight into the morphogenesis and function of the companion layer in hair follicles
AU - Gu, Li Hong
AU - Coulombe, Pierre A.
N1 - Funding Information:
We thank Dr Henry Sun, Dr Michael O'Guin, and Dr Lutz Langbein for their gift of antibodies, Dr Carol Trempus, Dr Sarah Millar, and Dr George Cotsarelis for comments, and members of the Coulombe laboratory for support. These studies were supported by NIH Grant AR42047.
PY - 2007/5
Y1 - 2007/5
N2 - 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.
AB - 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.
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U2 - 10.1038/sj.jid.5700673
DO - 10.1038/sj.jid.5700673
M3 - Article
C2 - 17170733
AN - SCOPUS:34247243262
SN - 0022-202X
VL - 127
SP - 1061
EP - 1073
JO - Journal of Investigative Dermatology
JF - Journal of Investigative Dermatology
IS - 5
ER -