title: Expression of RNA-binding protein Musashi in hair follicle development and hair cycle progression.
abstract: Epithelial stem cells reside in the hair follicle (HF) bulge region and possess the ability to differentiate into a variety of cutaneous epithelial cells. The evolutionarily conserved Musashi family of RNA-binding proteins is associated with maintenance and/or asymmetric cell division of neural progenitor cells, and a mammalian Musashi protein is expressed in various epithelial stem/progenitor cells, including gut, stomach, and mammary gland. Thus, we hypothesized that Musashi might be expressed in stem cells and early progenitor cells of HF epithelium. Reverse transcriptase-polymerase chain reaction and immunoblotting identified Musashi-1 (Msi-1) and Musashi-2 (Msi-2) mRNA and protein in cultured mouse keratinocytes, but only Msi-1 was identified in human keratinocytes. In mice, immunohistochemical studies showed that Msi-1 and Msi-2 were expressed in the epidermis and HFs from E14.5 until adulthood. In the early anagen phase, Msi-1 and Msi-2 were expressed in the bulge and secondary germ cells and subsequently in inner root sheath (IRS) cells, especially the middle IRS cells, during the late anagen phase. In human skin, Msi-1 was detected in fetal HF cells but not in adult HFs. These observations suggest that Musashi functions not only in the asymmetric division of early progenitor cells but also in the differentiation of IRS cells during HF development and hair cycle progression.
authors.affiliation: Department of Dermatology, Hokkaido University Graduate School of Medicine, N15 W7, Sapporo 060-8638, Japan.
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Sugiyama-Nakagiri
authors.forename: Masashi
authors.initials: M
authors.lastname: Akiyama
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Shibata
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Okano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimizu
mesh_terms: D000328:Adult; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D004622:Embryo, Mammalian; D005333:Fetus; D015870:Gene Expression; D018859:Hair Follicle / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D016601:RNA-Binding Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*
chemical_list: C491297:MSI1 protein, human; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins