title: The RNA-binding protein Musashi is required intrinsically to maintain stem cell identity.
abstract: A key goal of regenerative medicine is an understanding of the genetic factors that define the properties of stem cells. However, stem cell research in mammalian tissue has been hampered by a paucity of stem cell-specific markers. Although increasing evidence suggests that members of the Musashi (Msi) family of RNA-binding proteins play important functions in progenitor cells, it remains unclear whether there is a stem cell-autonomous requirement for Msi because of an inability to distinguish stem cells from early-lineage cells in mammalian tissues. Here, using the Drosophila testis as a model system for the study of stem cell regulation, we show specific evidence for a cell-autonomous requirement for Msi family proteins in regulating stem cell differentiation, leading to the identification of an RNA-binding protein required for spermatogonial stem cell maintenance. We found that loss of Msi function disrupts the balance between germ-line stem cell renewal and differentiation, resulting in the premature differentiation of germ-line stem cells. Moreover, we found that, although Msi is expressed in both somatic and germ cells, Msi function is required intrinsically in stem cells for maintenance of stem cell identity. We also discovered a requirement for Msi function in male meiosis, revealing that Msi has distinct roles at different stages of germ cell differentiation. We describe the complementary expression patterns of the murine Msi paralogues Msi1 and Msi2 during spermatogenesis, which support the idea of distinct, evolutionarily conserved roles of Msi.
authors.affiliation: Department of Anatomy and Cell Biology, University of Melbourne, Melbourne, Victoria 3010, Australia.
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Siddall
authors.forename: Eileen A
authors.initials: EA
authors.lastname: McLaughlin
authors.forename: Neisha L
authors.initials: NL
authors.lastname: Marriner
authors.forename: Gary R
authors.initials: GR
authors.lastname: Hime
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000166:cytology / Q000378:metabolism; D008297:Male; D051379:Mice; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D013091:Spermatogenesis; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D013737:Testis / Q000378:metabolism; D013997:Time Factors
chemical_list: D029721:Drosophila Proteins; C104786:Msi1h protein, mouse; C499059:Msi2h protein, mouse; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; C088623:msi protein, Drosophila