Myopathy in purine metabolic disorders: a model for adenylosuccinate synthase deficiency

Project Summary/ Abstract Inborn Errors of Purine Metabolism are linked with specific and often severe neural and muscle dysfunctions. However, the precise mechanisms through which mutations in enzymes involved in the synthesis of key biological molecules lead to these distinct outcomes remain unclear. This proposal focuses on the investigation of adenylosuccinate synthase (ADSS), specifically the deficiency of the muscle-specific isoform, ADSSL1, linked to progressive myopathy in humans. Because of the importance of the purine nucleotide cycle in maintaining energy stores (ATP levels) in tissues like muscle with intense energy requirements, the perturbation of the purine nucleotide cycle upon loss of ADSS activity is proposed to underlie phenotypes. However this hypothesis has not been investigated because there are no established animal models for study of this disorder. The primary objective of this research is to develop a C. elegans model for ADSS deficiency. C. elegans, with its powerful genetic system, provides an ideal platform for uncovering the etiology of myopathy and mobility phenotypes associated with ADSS deficiency, a crucial step in envisioning novel therapeutic strategies. ADSS deficiency in C. elegans manifests in mobility dysfunction and metabolic perturbations. The specific aims are structured as follows: Aim 1 focuses on developing genetic tools for the analysis of adss-1 function. The plan focuses on developing a degron-based system for temporal and spatial control of ADSS-1 function and engineering human disease allele knock-ins. These tools will be used to determine tissue-specific, developmental, or acute functions of ADSS-1, as well as to characterize structural defects in muscle cells and broader metabolic changes in metabolism that are associated with adss-1 knockdown. Aim 2 involves investigating alternative hypotheses about the etiology of various adss-1 phenotypes and testing candidate therapeutics. Comparisons with other genes in the de novo purine biosynthesis pathway and purine nucleotide cycle pathway will elucidate the role of these pathways in phenotypic outcomes. Supplementation and genetic experiments will assess the role of ADSS-1 product (S-AMP) and purine homeostasis in phenotypic outcomes. Finally, candidate therapeutics, including the ADSS product S-AMP, will be tested using the C. elegans model. The anticipated outcomes include significant progress toward therapeutic strategies for a disorder lacking treatment options. Insights gained will contribute to understanding how purine metabolism influences cellular processes and biochemical pathways, potentially revealing novel therapeutic targets for other muscle disorders associated with aberrant purine metabolism.