G-Protein signaling increases germline stem cell activity in Drosophila males in response to multiple rounds of mating

Though adult tissues are maintained by homeostasis, little is known about how their precursor cells adjust to a demand for specialized cells to account for changes during development or in the environment. In the male gonad, the ability to respond to a demand for increased gamete production, commonly referred to as reproductive plasticity, is essential for the fitness of an individual and the species. Here, we show that a demand for sperm, caused by repeated male mating, increased germline stem cell (GSC) division frequency and the production of gametes. The increase in GSC divisions depended on activity of four classical G-protein coupled receptors and downstream signaling molecules within the germline cells. Thus, GSCs are reliant on the GPCR stimulus. Among the signaling molecules, Serotonin appeared sufficient to accelerate GSC divisions in non-mated males, making the highly conserved Serotonin receptors key players in the mechanism regulating tissue replenishment.