Neuronal Prps is required for synaptic development and locomotor function in Drosophila melanogaster

Phosphoribosyl pyrophosphate synthetase (PRPS) produces phosphoribosyl pyrophosphate, which is a key precursor for nucleotide biosynthesis. Mutations in the human PRPS1 gene cause Charcot-Marie-Tooth disease and other neuropathies. However, how PRPS1 dysfunction impairs neuronal and synaptic function remains unclear. In this study, we used Drosophila melanogaster to determine the effects of reduced Prps expression on neurons in vivo. Neuronal knockdown of Prps caused severe locomotor impairment in third instar larvae and in adults, which indicated a critical requirement for Prps in motor output. At the neuromuscular junction, Prps depletion led to a reduced number of synaptic boutons accompanied by enlargement of boutons, disrupted presynaptic active zone organization indicated by decreased Bruchpilot puncta, and loss of Futsch-positive microtubule loops. These findings suggested destabilization of cytoskeletal architecture. These phenotypes were consistently observed using independent RNAi lines. Importantly, neuronal expression of Drosophila Prps or human PRPS1 significantly rescued locomotor activity, synaptic growth, active zone organization, and microtubule structure, which are caused by the expression of the Prps short hairpin RNA. The rescue by Drosophila Prps and human PRPS1 highlights evolutionary conservation of PRPS1 function and suggests Drosophila as a model for analyzing PRPS1-associated neuropathies.