Investigating the effects of neurometabolic disease-causing genes on synapse function in drosophila melanogaster

One subgroup of rare metabolic diseases, synaptopathies, add up to considerable amounts of rare metabolic diseases, yet the lack in the knowledge in underpinnings leading to synaptic dysfunction results in lack of appropriate diagnostics and interventions in this subgroup. Our group has identified several patients that harbor mutations in genes that hold the potential for being important players of synapse function, UNC79 and MBOAT7 being two of them. UNC79 is one of the accessory subunits of a sodium leak channel, NALCN, which is composed of NALCN, UNC80 and UNC79 subunits. It is widely expressed in the brain and known to inhabit neuropils in Drosophila. Its expression pattern is in parallel to brp, a conserved active zone component renown to give the shape to the active zones. MBOAT7, on the other hand, is an enzyme that attaches preferentially arachidonic acid to sn-2 positions of phosphoinositide (PI) in specifically brain tissues of mammals. PIs, are renown players of synapse function. In the light of information given above, we aimed to reveal the effects of UNC79 and MBOAT7 knockdowns on synapse size, number and morphology via combination of molecular biology and imaging techniques by using fruit fly as a model organism. Pan-neuronal and motoneuronal silencing of NALCN channel components -NALCN- UNC79, and UNC80- and motoneuronal silencing MBOAT7 ortholog in Drosophila 3rd instar larvae resulted in discrepancies in both brp and glutamate receptor levels and morphologies compared to control groups. Besides, pan-neuronal silencing MBOAT7 ortholog has no effect on brp and glutamate receptor intensities. Dissecting wild-type larvae in a time-dependent fashion showed that brp and glutamate receptor levels oscillate in 1b NMJs that protrude 4th muscle of 3rd instar larvae. Diet had a drastic effect on not only brp and glutamate receptor levels but also on brp and glutamate receptor spot shapes proving that environmental and intrinsic factors are important in oscillatory pattern. Dissecting motoneuronally silenced na in a time dependent fashion showed a shift in brp and glutamate receptor intensities compared to control groups.