Structure-Based Drug Repurposing Targeting Malonyl-CoA Decarboxylase for Treatment of Obesity

Abstract ID 92664 Poster Board 282 The main pathophysiological problem associated with obesity is the accumulation of cytosolic fatty acids and acceleration of fatty acid oxidation (FAO), leading to metabolic inflexibility. Malonyl-CoA is highly regulated in fatty acid synthesis, decarboxylated by malonyl-CoA decarboxylase (MLYCD), producing acetyl-CoA, which stimulates the mitochondrial uptake of free fatty acids for β-oxidation by relieving the malonyl-CoA-mediated inhibition of Carnitine palmitoyl transferase (CPT). Several pre-clinical and experimental studies have demonstrated that genetic or pharmacological inhibition of MLYCD can shift energy metabolism toward glucose oxidation by inhibiting CPT1 and FAO for treating ischemic heart diseases. That was coupled with elevated levels of malonyl-CoA, leading to inhibition of food intake. This shifts energy metabolism as a plausible therapeutic approach for obesity and associated metabolic disorders. However, up till now, there are no FDA-approved MLCYD inhibitors. We applied structure-based high throughput virtual screening coupled with biochemical validation to identify FDA-approved drug(s) targeting MLYCD and discovered Comp (A) that inhibited MLYCD activity with IC50 at 5.20±0.70 μM. Further biophysical studies revealed that Comp (A) induced post-covalent modification for MLYCD protein. Thermal shift assay showed that Comp (A) induced a significant shift in the MLYCD melting curves to suggest evidence of induced conformational changes for MLYCD. Our in vitro pre-clinical validation showed that Comp (A) significantly reduced lipid accumulation and triglyceride content of differentiated adipocytes (3T3-L1) cell lines, compared to vehicle-treated cells. Notably, subcutaneous administration of Comp (A) at two dose levels in high-fat diet-induced obese C57BL/6 mice decreased caloric intake, whole body weight, fat-to-lean ratio, and AUC for glucose and insulin tolerance tests compared to the vehicle-treated groups indicating glucose hemostasis and improved insulin sensitivity. Indirect calorimetry revealed that whole-body oxygen consumption (VO2) and carbon dioxide production (VCO2) were elevated in treated mice compared to control in both dark and light cycles, confirming increased metabolic rates in the treated obese mice group. In addition, there was an elevation in the respiratory exchange rate, indicating a shift in substrate preference utilization to glucose oxidation. Western blot analysis of the isolated liver tissue showed a significant reduction in MLYCD activity associated with significant elevation in the phosphorylation of AKT, improving insulin sensitivity and reduction in the phosphorylating signal of pyruvate dehydrogenase (pPDH), indicating activation of PDH and glucose oxidation. Oil Red O staining for the isolated liver tissues showed a significant reduction in lipid accumulation. Importantly, our study offers the first-in-class FDA-approved MLYCD inhibitors that could alleviate obesity through metabolic reprogramming and shifting to glucose oxidation. Start-up funds from the TTUHSC research office and SOP support this work. We thank Openeye for a free academic license.