第991回生物科学セミナー
Stem cell renewal and adult sexual identity in the testis niche
Erika Matunis Ph. D（Professor, Johns Hopkins University School of Medicine,Department of Cell Biology）
2014年09月09日(火) 16：00～ 理学部2号館 講堂
Qing Ma, Matthew Wawersik and Erika Matunis
Department of Cell Biology and the Institute for Cellular Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA
Stem cells reside in specific microenvironments, or niches, where local signals promote their maintenance. Spermatogonial stem cells in the testis provide a lifetime supply of sperm, making this organ an excellent model for studying stem cell biology. We focus on the Drosophila testis, as it contains a single morphologically distinct niche that can be probed with sophisticated genetic tools. This niche is comprised of a cluster of quiescent somatic cells called the hub, to which spermatogonial (or germline) and somatic stem cells (called cyst stem cells, or CySCs) adhere. Local Jak-STAT signaling was known to promote somatic cyst stem cell (CySC) renewal through several effectors, including the transcription factor Chronologically inappropriate morphogenesis (Chinmo). Here we find that Chinmo also prevents sex transformation of CySCs by promoting expression of the canonical male sex determination factor DoublesexM (DsxM) in CySCs and their progeny. Ectopic expression of DsxM in CySCs rescues the chinmo sex transformation phenotype, placing Chinmo upstream of DsxM. The Dsx homologue DMRT1 prevents the male-to female conversion of differentiated somatic cells in mammals, but its regulation is not well understood. Our work indicates that sex maintenance occurs in adult somatic stem cells, and that this highly conserved process is governed by conserved effectors of niche signals.
