title: Molecular characterization of melanocyte stem cells in their niche.
abstract: Emerging evidence from stem cell (SC) research has strengthened the idea that SC fate is determined by a specialized environment, known as the SC niche. However, because of the difficulty of identifying individual stem cells and their surrounding components in situ, the exact mechanisms underlying SC regulation by the niche remain elusive. To overcome this difficulty, we employed melanocyte stem cells (MSCs), which allow the identification of individual SCs in the niche, the lower permanent portion of the hair follicle (HF). Here, we present molecular makers that can distinguish MSCs from other melanocyte (MC) subsets in the HF. We also describe a simple and robust method that allows gene expression profiling in individual SCs. After isolating individual MSCs from transgenic mice in which the MCs are marked by green fluorescence protein (GFP), we performed single-cell transcript analysis to obtain the molecular signature of individual MSCs in the niche. The data suggest the existence of a mechanism that induces the downregulation of various key molecules for MC proliferation or differentiation in MSCs located in the niche. By integrating these data, we propose that the niche is an environment that insulates SCs from various activating stimuli and maintains them in a quiescent state.
authors.affiliation: Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, 2-2-3 Minatojima Minami-machi, Kobe, Hyogo 650-0047, Japan. mosawa@cdb.riken.jp
authors.forename: Masatake
authors.initials: M
authors.lastname: Osawa
authors.forename: Gyohei
authors.initials: G
authors.lastname: Egawa
authors.forename: Siu-Shan
authors.initials: SS
authors.lastname: Mak
authors.forename: Mariko
authors.initials: M
authors.lastname: Moriyama
authors.forename: Rasmus
authors.initials: R
authors.lastname: Freter
authors.forename: Saori
authors.initials: S
authors.lastname: Yonetani
authors.forename: Friedrich
authors.initials: F
authors.lastname: Beermann
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Nishikawa
mesh_terms: D000818:Animals; D019070:Cell Lineage; D049109:Cell Proliferation; D015536:Down-Regulation; D020869:Gene Expression Profiling; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018859:Hair Follicle / Q000166:cytology*; D008544:Melanocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*
chemical_list: D049452:Green Fluorescent Proteins