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BAM15 Mediated Mitochondrial Uncoupling Protects Against Obesity and Improves Glycemic Control

ABSTRACT: Obesity is a leading cause of preventable death worldwide. Despite this, current strategies for the treatment of obesity remain ineffective at achieving long-term weight control. This is due, in part, to difficulties in identifying tolerable and efficacious small molecules or biologics capable of regulating systemic nutrient homeostasis. Here we demonstrate that BAM15, a mitochondrially targeted small molecule protonophore, stimulates energy expenditure and glucose and lipid metabolism to protect against diet-induced obesity. Exposure to BAM15 in vitro enhanced mitochondrial respiratory kinetics, improved insulin action, and stimulated nutrient uptake by sustained activation of AMPK. C57BL/6J mice treated with BAM15 were resistant to weight gain. Furthermore, BAM15 treated mice exhibited improved body composition and glycemic control independent of weight loss, effects attributable to drug targeting of lipid-rich tissues. We provide the first phenotypic characterization and demonstration of pre-clinical efficacy for BAM15 as a pharmacological approach for the treatment of obesity and related diseases.

SUBMITTER: Christopher, L Axelrod

PROVIDER: S-SCDT-EMM-2020-12088 | biostudies-other |

REPOSITORIES: biostudies-other

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Project description:Background and aim: Diacylglycerol kinase (DGK) isoforms catalyze an enzymatic reaction that removes diacylglycerol (DAG) and thereby terminates protein kinase C (PKC) signaling by converting DAG to phosphatidic acid (PA). We have reported that downregulation of DGKδ (type II isozyme) causes peripheral insulin resistance, metabolic inflexibility, and obesity. Our aim was to determine whether overexpression of DGKδ protects against the development of metabolic impairments and obesity. Methods: We generated a transgenic mouse model overexpressing the human DGKδ2 isoform under the myosin light change promoter (DGKδ TG). We performed deep metabolic phenotyping of DGKδ TG and wild-type mice fed chow or high-fat diet. Mice were also given free access to running wheels to examine the effects of DGKδ overexpression on exercise-induced metabolic outcomes. Results: DGKδ TG mice were leaner than wild-type littermates, with improved glucose tolerance, increased glycogen storage in skeletal muscle, and enhanced glucose uptake in white adipose tissue. Moreover, DGKδ TG mice were protected against high fat diet (HFD)-induced glucose intolerance and obesity. DGKδ TG mice had reduced epididymal fat pad weight, and enhanced lipolysis. Strikingly, DGKδ overexpression recapitulates the beneficial effects exercise on metabolic outcomes. DGKδ overexpression and exercise have a synergistic effect on body weight reduction. Microarray analysis of skeletal muscle confirmed an overlap between genes associated with exercise and DGKδ overexpression. Gene ontology signatures of exercise and DGKδ overexpression were related to lipid storage, extracellular matrix, and glycogen biosynthesis pathways. Conclusion: We identify a role for DGKδ in glucose and energy homeostasis. Overexpression of DGKδ induces adaptive changes in both skeletal muscle and adipose tissue, resulting in protection against high fat diet-induced obesity. DGKδ overexpression recapitulates exercise-induced adaptations on energy homeostasis and skeletal muscle gene expression profiles.

Project description:ObjectivesLoss of functional β-cell mass is a key factor contributing to poor glycemic control in advanced type 2 diabetes (T2D). We have previously reported that the inhibition of the neuropeptide Y1 receptor improves the islet transplantation outcome in type 1 diabetes (T1D). The aim of this study was to identify the pathophysiological role of the neuropeptide Y (NPY) system in human T2D and further evaluate the therapeutic potential of using the Y1 receptor antagonist BIBO3304 to improve β-cell function and survival in T2D.MethodsThe gene expression of the NPY system in human islets from nondiabetic subjects and subjects with T2D was determined and correlated with the stimulation index. The glucose-lowering and β-cell-protective effects of BIBO3304, a selective orally bioavailable Y1 receptor antagonist, in high-fat diet (HFD)/multiple low-dose streptozotocin (STZ)-induced and genetically obese (db/db) T2D mouse models were assessed.ResultsIn this study, we identified a more than 2-fold increase in NPY1R and its ligand, NPY mRNA expression in human islets from subjects with T2D, which was significantly associated with reduced insulin secretion. Consistently, the pharmacological inhibition of Y1 receptors by BIBO3304 significantly protected β cells from dysfunction and death under multiple diabetogenic conditions in islets. In a preclinical study, we demonstrated that the inhibition of Y1 receptors by BIBO3304 led to reduced adiposity and enhanced insulin action in the skeletal muscle. Importantly, the Y1 receptor antagonist BIBO3304 treatment also improved β-cell function and preserved functional β-cell mass, thereby resulting in better glycemic control in both HFD/multiple low-dose STZ-induced and db/db T2D mice.ConclusionsOur results revealed a novel causal link between increased islet NPY-Y1 receptor gene expression and β-cell dysfunction and failure in human T2D, contributing to the understanding of the pathophysiology of T2D. Furthermore, our results demonstrate that the inhibition of the Y1 receptor by BIBO3304 represents a potential β-cell-protective therapy for improving functional β-cell mass and glycemic control in T2D.

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BAM15 Mediated Mitochondrial Uncoupling Protects Against Obesity and Improves Glycemic Control

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