Résumé
The SLC7A heterodimeric amino acid transporter family plays a crucial role in cell and tissue physiology and metabolism in mammals, and is a key factor in some human cancers. Five potential SLC7A orthologs -minidiscs, genderblind, JhI-21, sobremesa and CG1607- have been identified in Drosophila. To unravel the role of SLC7A transporters in the amino acid signalling in the adult central nervous system (CNS) we focused on MINIDISCS (MND) transporter. MND is expressed in various cells in the CNS. We already highlighted the role of MND in IPCs as a crucial factor for DILP secretion and sugar metabolism. Here we show that MND is also expressed in some neurons forming the α/β _and γ _lobes of the mushroom bodies (MB). Downexpression of mnd in these neurons impairs the role of various amino-acids on MB activity using live calcium imaging. Surprisingly, we found that MND is an important glutamatergic actor in these neurons. We investigated the genetic coexpression of MND with various glutamatergic receptors, and we found that ionotropic (NMDAR, KAINATE, GLUCLα) and metabotropic (dmGLUR) receptors are co-expressed in the MB. We also found that downstream effectors of MND, such as Glutamate Deshydrogenase (GDH) and TOR are also involved in glutamatergic response in these kenyon cells. These results strongly support a key role played by MND in glutamatergic activity control in Drosophila melanogaster. This information opens fascinating new field of investigations, which could allow a better understanding of how nutrients and simple molecules, such as glutamate, can influence neuronal activity.