Neuronal octopamine signaling regulates mating-induced germline stem cell proliferation in femaleDrosophila melanogaster

Stem cells fuel the development and maintenance of tissues. Many studies have addressed how local signals from neighboring niche cells regulate stem cell identity and their proliferative potential. However, the regulation of stem cells by tissue-extrinsic signals in response to external cues remains poorly understood. Here we report that efferent octopaminergic neurons projecting to the ovary are essential for germline stem cell (GSC) proliferation in response to mating in female Drosophila . The neuronal activity of the octopaminergic neurons is required for mating-induced GSC proliferation as they relay the mating signal from Sex peptide receptor-positive cholinergic neurons. Octopamine and its receptor Oamb are also required for mating-induced GSC proliferation via intracellular Ca 2+ signaling. Moreover, we identified Matrix metalloproteinase-2 as a downstream component of the octopamine-Ca 2+ signaling to induce GSC proliferation. Our study provides a mechanism describing how neuronal system couples stem cell behavior to external cues through stem cell niche signaling.