Ionotropic glutamate receptor expression and function in the Drosophila testis stem cell niche.

Adult stem cells are required to maintain tissue homeostasis and understanding their regulation is essential to leveraging their utility. Here we report that seven transgenic ionotropic glutamate receptor (iGluR) subunit reporter lines are variably expressed in hub cells of the Drosophila testis stem cell niche, suggesting a novel form of inter-organ communication for this tissue. While HCR-FISH confirms that one of the iGluR subunits, GluRIIA , is transcribed in hub cells, we do not detect GluRIIA protein expression. Furthermore, hub cells are not sensitive to exogenous glutamate and hub-specific knockdown of the essential iGluR subunits does not phenotypically affect cells of the testis apex. Altogether this suggests that iGluRs are not essential for stem cell niche homeostasis.