Germ cells commit somatic stem cells to differentiation following priming by PI3K/Tor activity in the Drosophila testis

• Published in: PLoS genetics Vol. 17; no. 12; p. e1009609
• Main Authors: Yuen, Alice C, Hillion, Kenzo-Hugo, Wang, Ruoxu, Amoyel, Marc
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 13.12.2021; Public Library of Science (PLoS)
• Subjects: Adult Stem Cells - cytology; Analysis; Animals; Biology and Life Sciences; Cell Differentiation - genetics; Cell Self Renewal - genetics; Drosophila; Drosophila melanogaster - genetics; Drosophila melanogaster - growth & development; Drosophila Proteins - genetics; Germ cells; Germ Cells - growth & development; Growth; Male; Phosphatidylinositol 3-Kinases - genetics; Physiological aspects; Research and Analysis Methods; Signal Transduction - genetics; Stem Cell Niche - genetics; Stem cells; Testis - growth & development; Testis - metabolism; TOR Serine-Threonine Kinases - genetics; United States; United Kingdom
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1009609

How and when potential becomes restricted in differentiating stem cell daughters is poorly understood. While it is thought that signals from the niche are actively required to prevent differentiation, another model proposes that stem cells can reversibly transit between multiple states, some of which are primed, but not committed, to differentiate. In the Drosophila testis, somatic cyst stem cells (CySCs) generate cyst cells, which encapsulate the germline to support its development. We find that CySCs are maintained independently of niche self-renewal signals if activity of the PI3K/Tor pathway is inhibited. Conversely, PI3K/Tor is not sufficient alone to drive differentiation, suggesting that it acts to license cells for differentiation. Indeed, we find that the germline is required for differentiation of CySCs in response to PI3K/Tor elevation, indicating that final commitment to differentiation involves several steps and intercellular communication. We propose that CySC daughter cells are plastic, that their fate depends on the availability of neighbouring germ cells, and that PI3K/Tor acts to induce a primed state for CySC daughters to enable coordinated differentiation with the germline.