title: A skin microRNA promotes differentiation by repressing 'stemness'.
abstract: In stratified epithelial tissues, homeostasis relies on the self-renewing capacity of stem cells located within the innermost basal layer. As basal cells become suprabasal, they lose proliferative potential and embark on a terminal differentiation programme. Here, we show that microRNA-203 is induced in the skin concomitantly with stratification and differentiation. By altering miR-203's spatiotemporal expression in vivo, we show that miR-203 promotes epidermal differentiation by restricting proliferative potential and inducing cell-cycle exit. We identify p63 as one of the conserved targets of miR-203 across vertebrates. Notably, p63 is an essential regulator of stem-cell maintenance in stratified epithelial tissues. We show that miR-203 directly represses the expression of p63: it fails to switch off suprabasally when either Dicer1 or miR-203 is absent and it becomes repressed basally when miR-203 is prematurely expressed. Our findings suggest that miR-203 defines a molecular boundary between proliferative basal progenitors and terminally differentiating suprabasal cells, ensuring proper identity of neighbouring layers.
authors.affiliation: Howard Hughes Medical Institute, The Rockefeller University, New York City, New York 10065, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Yi
authors.forename: Matthew N
authors.initials: MN
authors.lastname: Poy
authors.forename: Markus
authors.initials: M
authors.lastname: Stoffel
authors.forename: Elaine
authors.initials: E
authors.lastname: Fuchs
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D019295:Computational Biology; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012867:Skin / Q000166:cytology* / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology*; D015027:Zebrafish / Q000235:genetics
chemical_list: D020413:3' Untranslated Regions; D035683:MicroRNAs