Development of Novel Blood-Brain Barrier Impenetrable GABA Transaminase Inhibitors to Treat Hyperglycemia, Hyperinsulinemia, and Insulin Resistance
Abstract
Peer Reviewed Medical Research Program Portfolio: Nutrition and Metabolism Topic Area: Diabetes, Continuum of Care: Treatment Strategic Goal: Develop and test novel treatment strategies for mitochondrial diseases, especially those read to progress to the clinic, including repurposing existing drugs or non-prescription treatment options Rationale: The severity and incidence of type 2 diabetes is directly related to fat accumulation in the liver. We have shown that liver fat accumulation increases liver production and release of ?-aminobutyric acid (GABA), an inhibitory neurotransmitter. Liver-produced GABA stimulates insulin release and causes insulin resistance at skeletal muscle. This GABA is produced by GABA transaminase and production can be eliminated by inhibiting GABA transaminase. Inhibiting GABA transaminase rapidly restores insulin sensitivity and normo-insulinemia in diet-induced obese mice. In people with obesity, the amount of GABA transaminase in the liver is positively correlated with serum insulin and homeostasis model assessment-estimated insulin resistance (HOMA-IR). We performed computer-based docking experiments to screen 80,000 compounds and identified 71 compounds that were predicted to bind to the active site of GABA transaminase. We showed that four of these compounds effectively inhibited GABA-T at concentrations 6-16 times lower than commercially available inhibitors, had little non-specific activity at other transaminases, inhibited both mouse and human GABA-T similarly, and were predicted to not cross into the brain. These four lead compounds improved insulin sensitivity and lowered serum insulin in diet-induced obese mice. Computer-based screening to expand our pool of effective compounds yielded five more compounds that were similarly effective. We propose a series of in silico (computer-based; Aim 1), in vitro (lab-based; Aim 2), and in vivo preclinical (mouse; Aim 3) studies aimed at optimizing and validating novel GABA-T inhibitors that will limit obesity-induced hyperinsulinemia and insulin resistance. Overall Goal: To develop, optimize and validate novel blood-brain barrier impenetrable GABA transaminase inhibitors through computer (Aim 1), benchtop (Aim 2), and mouse (Aim 3) studies. Hypothesis: Through iterative computer (Aim 1), benchtop (Aim 2), and mouse (Aim 3) studies, we will develop novel GABA transaminase inhibitors with key structural components required to ensure efficacy and specificity, while preventing transport across the blood-brain barrier. Innovative Aspects of the Research: We are developing unique inhibitors against a recently identified novel target, GABA-transaminase, to treat insulin resistance. We have a strong foundation of nine effective compounds, benchtop tests of efficacy against both the human and mouse protein, and tests of efficacy in the diet-induced obese mouse. Study Design: We intend to perform Aims 1, 2, and 3 in multiple iterations, allowing our results from the lab (Aim 2) and mouse (Aim 3) studies to inform computer-based drug design. Aim 1 will include molecular modeling using the Schrödinger Molecular Modeling Suite to understand protein/compound interactions and design chemical modifications that will enhance efficacy and specificity. Aim 2 will include tests of off-target binding using surface plasmon resonance, enzyme activity assays, 1-D NMR, and ex vivo activity assays. Aim 3 will include basal measures of glucose homeostasis, insulin and oral glucose tolerance tests, and hyperinsulinemic euglycemic clamps in the diet-induced obese mouse. Expected Results: We expect to develop and validate novel, specific, highly effective, blood-brain barrier impenetrable GABA-transaminase inhibitors. Impact to Research Field: Liver GABA production was only recently identified as a signal that induces insulin resistance. The development of novel inhibitors would extend research aimed at understanding the ro
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2024
- Source ID
- HT94252310810
Entities
People
- Benjamin Renquist
Organizations
- United States Army
- University of Arizona