Elevated mTORC1 Signaling in Skeletal Muscle Exacerbates Diet-Induced Hyperglycemia and Mitochondrial H ₂ O ₂ Production

The mechanisms underlying skeletal muscle insulin resistance are not completely understood. This study aimed to determine if hyperactive mTORC1 signaling via disruption of the GATOR1 complex is sufficient to drive insulin resistance and mitochondrial dysfunction in skeletal muscle with or without a western diet. Muscle-specific DEPDC5 knockout mice (a component of GATOR1) or littermate controls were administered a western diet or control chow for 12 weeks and assessed for muscle-specific glucose uptake, oral glucose tolerance, and mitochondrial function (respiration and H 2 O 2 production), as well as various measures of physical function. Western diet increased fasting glucose by 32 mg/dL (p<0.001) and impaired glucose tolerance (33% increase in area under the curve; p<0.0001), both of which appeared worse in knockout mice (13% and 7%, respectively), though this was not statistically significant. Additionally, western diet increased HbA1c by about 5% (p=0.10), and reduced grip strength by 12% (p<0.05). No statistical differences were observed in muscle-specific glucose uptake between groups. Neither genotype nor diet affected mitochondrial respiration, apart from a 30% increase in complex IV maximal activity in knockout mice (p=0.09). However, knockout mice fed a western diet exhibited an approximately 2-fold increase in mitochondrial H 2 O 2 production compared to controls across a range of physiological relevant energy states (p<0.05). These results suggest that western diet feeding impairs glycemic control even in the absence of altered mitochondrial function, and that increased mTORC1 signaling in skeletal muscle may exacerbate the negative effects of western diet by increasing mitochondrial H 2 O 2 production. NIH R56AG051267; NIH P30AG013319 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.