Pharmacologic Uncoupling of Skeletal Muscle Mitochondria Promotes Glucose Metabolism

Abstract

Mitochondrial uncoupling was one of the earliest pharmacologic approaches to the treatment of obesity-related diseases. However, low mitochondrial specificity and negative off-target effects limited the viability of such agents. BAM15 is a small molecule recently identified for its potent ability to uncouple mitochondria. Thus, the purpose of this investigation was to explore the physiological effects of BAM15 on skeletal muscle mitochondrial function and glucose metabolism. C2C12 myotubes were incubated with either vehicle or BAM15 at varying concentrations for 16 hours. Cell viability was assessed by detection of dehydrogenase activity. Cytotoxicity was measured by a Caspase 3/7 activity assay. Glucose uptake was measured using [3H]-2-deoxy-D-glucose in the presence and absence of insulin. Oxygen consumption rates were measured using an XF24 extracellular flux analyzer. Cells were harvested for the assessment of plasma membrane GLUT4 and protein signaling via Western blot. Cells treated with BAM15 were viable up to 100 μM, and lacked toxicity up to 50 μM, compared to vehicle. BAM15 significantly increased glucose uptake (P<0.05) at concentrations as low as 6.25 μM. Concentrations of 25 μM and above exhibited a 2-4 fold greater glucose uptake than insulin (P<0.05), which saturated at 50 μM. BAM15 significantly increased basal oxygen consumption (P<0.05), while markedly reducing coupling efficiency (P<0.05). BAM15 upregulated primary energy homeostasis pathways via activation of AKT (t3and s473), AS160 (t642), and AMPK (t172). Additionally, BAM15 increased plasma membrane GLUT4 translocation (P<0.05). BAM15 is a pharmacologically active compound with low toxicity and mitochondrial specificity capable of inducing glucose metabolism in skeletal muscle. These data provide compelling evidence for future investigation of BAM15 as a potential treatment for diabetes and other obesity-related metabolic diseases. Disclosure M.E. Hull: None. C.L. Axelrod: None. K.M. Fitzgerald: None. J. Sacks: None. J.P. Kirwan: None.