Exercise Improves Exosome Function via Increasing Extracellular SOD and Cu transporter ATP7A to Restore the Impaired Angiogenesis in Type 2 Diabetic Mice

Abstract

BackgroundExosomes, a key player in cell‐cell communication, derived from diabetic animals/cells have detrimental effects. Exercise training has beneficial effects to improve endothelial dysfunction in metabolic disease such as diabetes mellitus (DM), but its mechanisms are poorly understood. Extracellular superoxide dismutase (ecSOD) is a major secretory copper (Cu) containing antioxidant enzyme in the vasculature that catalyzes the dismutation of O2− to H2O2 and its full activity requires Cu transporter ATP7A to get its catalytic cofactor Cu. Our lab reported that ATP7A‐ecSOD pathway is impaired in vascular tissue of DM, which induces endothelial dysfunction. Here we tested the hypothesis that exercise improves exosome function via regulating ATP7A‐ecSOD in type2 diabetes to restore their angiogenic effects.Methods and ResultsExosomes were isolated using differential ultracentrifugation method from plasma of control C57Bl6 and type2 diabetes mice induced by high fat diet, which were sacrificed after 2 weeks of volunteer wheel exercise. Isolated plasma exosomes were characterized by Nanosight, transmission electron microscopy and exosome marker expression (CD63, CD81 and Tsg101, assessed by western analysis). Endothelial migration using modified Boyden chamber method and capillary tube formation on Matrigel in human endothelial cells (ECs) were used to assess the effects of isolated exosomes on angiogenic responses. Exosome counts were increased (6.2 fold) in exercised control mice vs sedentary mice. Relative to sedentary mice, exosomes from exercised mice had an increase (1.4 fold) in both EC migration and tube formation. Furthermore, protein expression levels of ATP7A (3.4 fold) and ecSOD (1.9 fold) were significantly increased in exosomes from exercised control mice compared to sedentary mice. Exosomes from diabetic mice significantly decreased EC migration (45% inhibition) as well as ATP7A and ecSOD expression compared to those from control mice. Of note, exercise improved exosome dysfunction of diabetic mice by increasing ATP7A and ecSOD expression, which in turn restored impaired cell migration (1.9 fold increase) and tube formation (1.5 fold increase). To investigate the function of ecSOD in exosomes, we used exosomes from ecSOD knockout (KO) mice as well as conditioned media from ecSOD overexpressing cells. Exosomes from ecSOD KO mice with exercise showed impaired angiogenic responses in ECs, mimicking diabetic exosomes, while exosomes overexpressing ecSOD enhanced angiogenesis.ConclusionsExercise improves exosome function via increasing ecSOD and ATP7A expression, which restores their angiogenic function in type2 diabetes. Our study will provide new insights into exercise‐induced ATP7A‐ecSOD in exosomes as potentially therapeutic target for diabetic vascular complications.Support or Funding InformationNIHR01HL135584 (M.U.‐F.), R01HL116976 (T.F/M.U.‐F.), R01HL133613 (T.F/N.U.‐F), R01HL070187 (T.F.), R01HL134354 (Y.T), Department of Veterans Affairs Merit 2I01BX001232 (T.F.).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.