The formation and function of chemical synapses is critical for information transfer within the nervous system. This proposal focuses on the functional development of the glutamatergic synapse, utilizing a forward genetic approach at the Drosophila neuromuscular junction (NMJ). With NIH support over the past 5 years. we have systematically mutated the third chromosome of Drosophila (ca. 40% of the genome) and screened to identify 38 mutant complementation groups with severe NMJ synaptic dysfunction phenotypes. All of these 38 complementation groups have been mapped to defined genomic locations using both recombination and deficiency mapping techniques. This proposal is to analyze three of the genes identified in this screen, each of which is required for glutamatergic synaptogenesis during embryonic development. For each gene product, a specific role at the synapse has been hypothesized based on a large body of preliminary experimental work. These hypotheses will be tested in this proposal.This proposal has four specific aims.
Aim I is to test the hypothesis that the mind the gap (mtg) gene encodes a prolyl.4.hydroxylase-a protein required for the formation of a collagen-based, synapse-specific extracellular matrix (ECM) which patterns and maintains postsynaptic glutamate receptor fields.
Aim 2 is to test the hypothesis that the bad reception (brec) gene encodes a novel protein, which is absolutely essential for the post-transcriptional synthesis and membrane insertion of postsynaptic glutamate receptors.
Aim 3 is to test the hypothesis that the slug-a-bed (slab) gene encodes the sole Drosophila ceramidase, which acts to control presynaptic development by determining the ratio of tethered (reserve) to docked (readily releasable) vesicles at presynaptic active zones.
Aim 4 is to continue our forward genetic screens to map, clone and characterize additional genes essential for synaptogenesis.Drosophila has proven to be a powerful system in which to identify genes underpinning fundamental aspects of nervous system development and function. Characterization of genes required for the functional formation of the glutamatergic synapse is particularly relevant to a number of health problems. Abnormal synaptic development and function are associated with inherited neurological diseases, injury, stroke and aging. Through systematic identification of genetic pathways underlying synaptic functional development, the proposed research will provide direct insight into molecular mechanisms related to the treatment of inherited synaptic diseases, age-related decline in synaptic function, and synaptic regeneration following injury.
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