From Metabolic Stress to Energy Enhancement: Unraveling Complex V Dimerization in Mitochondrial Disorders

Project Summary/Abstract: Leigh syndrome (LS) is a neurometabolic syndrome characterized by severe and progressive regression, often triggered by a variety of metabolic stressors. Despite LS represents the most frequent pediatric mitochondrial disease, therapeutic options are limited and non-targeted. LS is associated with a wide array of genetic defects, most converging on a common pathway leading to energy failure. This proposal builds upon a recent breakthrough in our understanding of LS. USMG5 is a gene encoding a small peptide associated with ATP synthase, the molecular rotor that converts protons to ATP. We described pathogenic variants in USMG5 causing LS. Moreover, we demonstrated that in this subgroup of patients with LS, the defect arises not from a dysfunction with the ATP synthase enzyme rather from the inability of such enzyme to dimerize. Stemming from this groundbreaking discovery, this investigation seeks to move beyond USMG5, and fill the gap present in current literature on the role of ATP synthase dimers in energy regulation and adaptation to metabolic stress. The ultimate goal is to understand this mechanism and harness it to ameliorate energy defect and provide preliminary data for a novel therapeutic approach for mitochondrial patients. Our research strategy will employ primary human fibroblasts, tissues, and knockout cell lines to replicate ATP synthase dimerization defects. In Aim 1, we will explore the biology of dimerization defects. By resolving sub-organelle levels with cutting edge techniques, we will investigate how inner mitochondrial structural abnormalities disrupt the protons` gradient, leading to ATP synthesis failure. Aim 2 will study ATP synthase dimers function as the 'gears' of energy production. The hypothesis is that ATP synthase dimerization allows mitochondria to match production to demand by optimizing proton force. We will use an integrative approach, combining standard biochemistry with innovative real-time in vivo imaging analysis, to assess cellular responses to various metabolic stressors mirroring those observed in LS. Aim 3 explores the therapeutic potential of manipulating dimerization. Preliminary investigations suggest promise in enhancing ATP synthase dimerization through genetic overexpression, offering a potential strategy for a range of energy metabolism disorders. This research marks a significant advancement in our understanding of the mitochondrial stress response, holding substantial therapeutic potential. Beyond its clinical implications, this endeavor signifies a major milestone in my journey as a physician-scientist. It will deepen my comprehension of mitochondrial physiology, expand my experimental toolkit through collaboration with my advisors, and closely involve my mentors in laying the foundation for my independent translational scientist career. The insights gained will serve as a cornerstone for my future contributions to the field and a significant stride in advancing therapeutic approaches for mitochondrial diseases.