The Drosophila germline stem cells (GSCs) remain as one of the most well-understood adult stem cells. The number of stem cells that self-renews and differentiates must be tightly controlled to maintain tissue homeostasis. The Drosophila GSCs are maintained by local signals emanated from the niche, which is composed of the surrounding somatic cells. Notably, GSC homeostasis is also known to be influenced by systemic signals and external stimuli. The Drosophila hormone ecdysone and its signalling cascade were found to regulate GSC homeostasis. The insulin signalling pathway as well as nutrient availability can also regulate GSC number. Furthermore, neuronal sex peptide signalling induced in female flies after mating was shown to increase GSC number. Hence, the Drosophila GSC system serves as a useful model towards understanding the mammalian stem cells. Compared with the mammalian stem cell models, the Drosophila GSC system is anatomically simpler where stem cells can be easily identified, imaged and manipulated genetically. Nevertheless, recent findings have facilitated our understanding into how GSCs and their neighbouring somatic cells sense and respond to changes in a variety of local, systemic and external stimuli.
Part of the book: Germ Cell