Role of RAGE in amyloid-induced pancreatic islet dysfunction in diabetes

项目摘要/摘要

PROJECT SUMMARY / ABSTRACT In type 2 diabetes (T2D), amyloid deposits composed of islet amyloid polypeptide (IAPP) are found within pancreatic islets. T2D islets also have impaired insulin secretion from β cells, dysregulated glucagon secretion from α cells, increased inflammation, and alterations in vasculature. Among multiple potential mechanisms linking amyloid deposition and islet dysfunction, the receptor for advanced glycation endproducts (RAGE) was recently shown to bind IAPP oligomers and mediate β cell toxicity in vitro, which results were also supported using a transgenic rodent model. But in vitro cell culture models, while valuable, do not fully replicate the complex environmental, intercellular, or temporal changes in living organisms. Furthermore, human and rodent islets differ in function, structure, cellular composition, and gene expression. Thus, to fully understand the pathogenesis of human disease, one must study these processes in human cells and tissues in the in vivo context. Such studies have been limited by the inability to obtain and manipulate these relatively inaccessible human tissues and by the lack of in vivo models in which to study them longitudinally. It therefore remains unknown if endogenously secreted IAPP oligomers act on the RAGE receptor in primary human β cells, if such signaling occurs in α cells, and what effect IAPP-RAGE signaling in specific cell types has on islet function. I hypothesize that IAPP oligomer-induced activation of RAGE receptors on β and α cells impairs human islet function and health in vitro and in vivo. To test my hypothesis using human islets, I will employ four novel techniques and reagents. 1) Our recently reported pseudoislet method will enable efficient genetic manipulation of specific islet cell types prior to reaggregation into functional cell clusters. 2) New intravital imaging techniques will allow longitudinal monitoring of amyloid formation in human pseudoislets transplanted into the mouse anterior chamber of the eye. 3) Transplantation of pseudoislets into a recently developed glucagon knockout mouse will permit accurate measurement of human glucagon secretion in vivo. 4) Application of single nuclear RNA sequencing approaches will permit assessment of transcriptional effects on specific cell types in transplanted pseudoislets. In Aim 1, I will test the hypothesis that RAGE mediates IAPP oligomer-induced β cell dysfunction in human islets in vitro and in vivo. In Aim 2, I will test the hypothesis that IAPP-RAGE signaling in ⍺ cells causes dysregulated glucagon secretion in human islets in vitro and in vivo. Completion of these aims will elucidate key mechanisms responsible for pathogenesis of T2D, opening avenues for study into new preventive and therapeutic approaches. I will benefit from the outstanding environment, collaboration, and mentorship at the Vanderbilt Diabetes Research and Training Center as I transition to independence as a physician-scientist.