title: Quantitative analysis of male germline stem cell differentiation reveals a role for the p53-mTORC1 pathway in spermatogonial maintenance.
abstract: p53 protects cells from DNA damage by inducing cell-cycle arrest upon encountering genomic stress. Among other pathways, p53 elicits such an effect by inhibiting mammalian target of rapamycin complex 1 (mTORC1), the master regulator of cell proliferation and growth. Although recent studies have indicated roles for both p53 and mTORC1 in stem cell maintenance, it remains unclear whether the p53-mTORC1 pathway is conserved to mediate this process under normal physiological conditions. Spermatogenesis is a classic stem cell-dependent process in which undifferentiated spermatogonia undergo self-renewal and differentiation to maintain the lifelong production of spermatozoa. To better understand this process, we have developed a novel flow cytometry (FACS)-based approach that isolates spermatogonia at consecutive differentiation stages. By using this as a tool, we show that genetic loss of p53 augments mTORC1 activity during early spermatogonial differentiation. Functionally, loss of p53 drives spermatogonia out of the undifferentiated state and causes a consistent expansion of early differentiating spermatogonia until the stage of preleptotene (premeiotic) spermatocyte. The frequency of early meiotic spermatocytes is, however, dramatically decreased. Thus, these data suggest that p53-mTORC1 pathway plays a critical role in maintaining the homeostasis of early spermatogonial differentiation. Moreover, our FACS approach could be a valuable tool in understanding spermatogonial differentiation.
authors.affiliation: a Vincent Center for Reproductive Biology; Vincent Department of Obstetrics and Gynecology; Massachusetts General Hospital; Harvard Medical School ; Boston , MA USA.
authors.forename: Mulin
authors.initials: M
authors.lastname: Xiong
authors.affiliation: a Vincent Center for Reproductive Biology; Vincent Department of Obstetrics and Gynecology; Massachusetts General Hospital; Harvard Medical School ; Boston , MA USA.
authors.forename: Ianina C
authors.initials: IC
authors.lastname: Ferder
authors.affiliation: a Vincent Center for Reproductive Biology; Vincent Department of Obstetrics and Gynecology; Massachusetts General Hospital; Harvard Medical School ; Boston , MA USA.
authors.forename: Yasuyo
authors.initials: Y
authors.lastname: Ohguchi
authors.affiliation: a Vincent Center for Reproductive Biology; Vincent Department of Obstetrics and Gynecology; Massachusetts General Hospital; Harvard Medical School ; Boston , MA USA.
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
mesh_terms: D053687:Adult Stem Cells / Q000166:cytology / Q000502:physiology*; D000818:Animals; D059447:Cell Cycle Checkpoints; D002454:Cell Differentiation; D005434:Flow Cytometry / Q000379:methods; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D018345:Mice, Knockout; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction; D013093:Spermatogonia / Q000166:cytology / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013737:Testis / Q000166:cytology / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D046912:Multiprotein Complexes; D016159:Tumor Suppressor Protein p53; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases
keywords: differentiation; germline stem cell; mTORC1; p53; spermatogonia