BLRD Research Career Scientist Award Application

Wm S. Middleton Memorial Veterans Hosp, Madison WI

Investigators

Abstract

Currently, the prevalence of diabetes in the VA patient population is approximately 25%, with many more Veterans at risk for diabetes due to obesity, aging, and poor lifestyle, as well as exposure to known diabetogenic chemicals in the line of duty. The number of Veterans with diabetes is certain to increase over the next decades. Therefore, developing new methods for preventing diabetes and identifying and properly treating diabetic patients is very timely and of great significance. Ongoing research in my laboratory is focused on two broad areas: 1) understanding the molecular mechanisms controlling insulin secretion from the pancreatic beta-cell and how these mechanisms are altered during the progression to type 2 diabetes (T2D), and 2) identifying biomarkers associated with beta-cell dysfunction in T2D. For over two decades, the focus of my research program has been elucidating the role of prostaglandin EP3 receptor (EP3), and its associated G protein, Gz, in regulating beta-cell function, proliferation, and survival. In Specific Aim 1 of my current BLR&D Merit Review Award, we are testing the hypothesis that loss of the catalytic alpha subunit of Gz, Gɑz, protects mice from T2D due to increased signaling through cholecystokinin A receptor (CCKAR). The research proposed in this aim is built off a long-standing and productive collaboration with Dr. Dawn Belt Davis, a VA-funded physician-scientist whose expertise is in understanding the islet autocrine and paracrine signaling pathways controlling beta-cell function and mass. In Specific Aim 2a of my current BLR&D Merit Review Award, we are elucidating the specific molecular mechanisms downstream of mouse and human EP3 splice variants in whole islets, correlating signaling changes with downstream effects on beta-cell function, proliferation, and survival. This research is being performed in collaboration with Dr. Matthew Merrins, a VA- funded investigator who uses innovative biosensors and molecular probes to study beta-cell metabolic and signal transduction processes. Our hypothesis is EP3 signals by Gɑz-dependent and -independent mechanisms, and that these mechanisms differ based on whether an EP3 splice variant is constitutively active vs. agonist stimulated. Finally, the native ligand for EP3 is prostaglandin E2, an arachidonic acid metabolite. Specific Aim 2b applies an innovative, high-throughput, ultrahigh resolution mass spectrometric approach for untargeted metabolomics, developed in collaboration with the highly accomplished analytical chemist Dr. Ying Ge, to islet lysates obtained from mice and human organ donors, correlating changes in the arachidonic acid metabolome during the progression to T2D with downstream effects on β-cell function, proliferation, and survival. Finally, a recent R01 application selected for funding complements and expands on these aims. During the Research Career Scientist (RCS) Award period, I will continue our currently funded research while simultaneously translating our findings into the clinical direction. First, our research into the molecular mechanisms of EP3/Gɑz signaling will further validate their potential as new T2D therapeutic targets and elucidate ways in which to block their signaling. Within the next five years, we also anticipate identifying a small molecule that selectively interferes with Gɑz’s interaction with constitutively active EP3 splice variants, relieving their inhibition on beta-cell second messenger signaling and downstream beta-cell function and mass. In parallel, will work with collaborators at UW Madison and the Medical College of Wisconsin to test methods to specifically target an EP3 antagonist and/or Gɑz antisense oligonucleotide specifically to the beta-cell. Finally, using the results of our metabolomics analysis, we will identify a small panel of metabolites significantly and independently associated with beta-cell dysfunction, testing whether the levels of these metabolites predict the responsiveness of VA patients failing metformin monotherapy to two gold-standard classes of T2D drugs. Finally, the Research Career Scientist Award support will allow us to collect the critical additional data to support my next round of Merit Review application.