Regulation of the Novel MSTN-GAL3-NOX1 Axis Reverses Obesity-Induced Skeletal Muscle Quality Decline Resulting in Improved Glycemic Indices and Restored Angiogenesis Following Ischemia
Authors: Guilfoyle-Speese Andrew , Rosewater Cody , Padgett Caleb , Stepp David , Fulton David 
Published: May 2024

Objective: To test the hypothesis that restored muscle quality achieved through myostatin KO improves angiogenesis in obese mice through the resolution of GAL3-NOX1-mediated endothelial dysfunction.Methods: db/db mice, a well-described model of obesity, were crossed with mice lacking myostatin (MSTN KO), a myokine that negatively regulates muscle differentiation and growth, galectin-3 (GAL3 KO), a pro-inflammatory/atherogenic RAGE (receptor for advanced glycation endproducts), and NADPH oxidase-1 (NOX1 KO), a TGF-b-stimulated primary producer of the reactive oxygen species (ROS) O2−, to generate db+/−-MSTN+/−, db+/−-GAL3+/−, and db+/−-NOX1+/− mice. We utilized nuclear magnetic resonance (NMR) spectroscopy to assess skeletal muscle (SKM) lean/fat content in db+/−-MSTN+/− mice. Muscle and plasma lipid content were analyzed via mass spectrometry. Mice were placed in metabolic cages and monitored with CLAMS (Comprehensive Lab Animal Monitoring System) in order to determine their whole-body metabolism. Insulin metabolism indices were determined via appropriate blood and plasma testing kits. Morphology of SKM was determined via microscopy of H&E and Mason’s Trichrome-stained gastrocnemius cross sections. Femoral artery ligation was used to stimulate in vivo angiogenesis in response to hind limb ischemia (HLI); whereas 1mm aortic rings cultured in ECBM (2% FBS) were used to study ex vivo angiogenesis. Gene expression was assessed by RNA-Seq and RT-qPCR. Results: MSTN deletion results in significantly increased SKM mass and restored SKM quality (i.e. morphology and metabolic function) without altering whole-body mass, fat percentage, or activity in obese (db−) mice. We observed that obesity inhibits and MSTN KO restores angiogenesis in both HLI and aortic ring assay models. Previous studies in our lab revealed that MSTN deletion was suffcient to restore endothelial function in db/db mice. Additionally, our lab has shown that GAL3 or NOX1 KO in db/db mice phenocopied the vascular improvements seen in db−-MSTN− mice without restoring SKM size or quality. RNA-Seq and RT-qPCR analysis of SKM and endothelial cells (ECs) revealed significant upregulation of GAL3 and NOX1 expression in db−-MSTN+ mice but not in db−-MSTN− and db−-GAL3− mice. Finally, either GAL3 or NOX1 deletion results in amended angiogenesis in obese animals. Conclusion: In summary, restoration of muscle quality in obese individuals provides potent protection of vascular and metabolic health. A correlate of this improvement is the attenuation of a novel MSTN-GAL3-NOX1 axis, which we have shown to mediate vascular inflammation/redox signaling in obesity. These data suggest that pharmacological targeting of upstream MSTN, downstream GAL3 and/or NOX1 could be effective in treating cardiovascular disease in the context of obesity and metabolic syndrome. A. C. Speese is supported by NIH 1F31HL165858-01A1. D.W. Stepp and D. J. Fulton are supported by NIH 1R01HL147159. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.