In vivo hepato-renal metabolic flux dysregulation in obesity

Project Summary The liver and kidney are the major organs where glucose biosynthesis is coupled to mitochondrial metabolism. Previous studies demonstrate that overnutrition accelerates whole-body gluconeogenesis (GNG) and citric acid cycle (CAC) activity in vivo. A limitation of prior research is that the unique contributions of the liver and kidney to whole-body GNG and CAC fluxes have been difficult to disentangle in vivo. The inability to discern hepatic from renal metabolic fluxes represents a significant gap in knowledge, as obesity may not only cause an ectopic accumulation of lipid but also an “ectopic redistribution” of gluconeogenic function that disproportionately stresses the kidney. We hypothesize that renal GNG and CAC activity are disproportionately elevated in obesity, which contributes to the dysregulation of whole-body glucose metabolism and promotes mitochondrial dysfunction and oxidative tissue damage in the kidney. The scientific aims of this proposal are to (i) determine whether the progressive development of obesity disproportionately impacts renal gluconeogenic and oxidative metabolism, (ii) assess whether gluconeogenic overload on the kidney accelerates oxidative metabolism and stress during obesity, and (iii) identify metabolic mechanism(s) by which SGLT2 inhibitor treatment reduces hepato-renal lipotoxicity in vivo. The aims of our project will be accomplished using a novel, metabolic flux modeling system that simultaneously determines gluconeogenic and oxidative metabolic fluxes in the liver and kidney in vivo. This work is innovative because it examines the etiology and treatment of metabolic disease through the lens of multi-organ fluxomics while focusing on an understudied aspect of gluco(dys)regulation. It is significant because it will identify organ-specific metabolic nodes that may be better targeted to improve glycemic control and reduce damage in the kidney and liver. Results from this K01 project, the unique expertise of each member of my mentoring committee, and the diabetes research infrastructure at Vanderbilt University will be leveraged to achieve my career objective of an independent career studying metabolic regulation in diabetic kidney disease and hypoglycemic counter-regulation. As such, this project integrates a career development plan with the training needed to bolster my disease-state expertise, grantsmanship, and expand my analytical capabilities to ensure a smooth transition toward research independence.