Regulation of ER Homeostasis and Cell Cycle by Pax4 Enhances β-Cell Survival and Protects Mice Against Experimental Autoimmune Diabetes

Strategies to enhance islet b-cell survival and regeneration while refraining inflammation through manipulation of molecular targets would provide means to stably replenish the deteriorating functional b-cell mass detected in both Type 1 and Type 2 Diabetes Mellitus (T1DM and T2DM). Herein we report that over expression of the islet enriched transcription factor Pax4 refrains development of hyperglycemia in the RIP-B7.1 mouse model of T1DM through reduced insulitis, decreased b-cell apoptosis correlating with diminished DNA damage and increased proliferation. Transcriptomics revealed up regulation of genes involved in immunomodulation, cell cycle and ER homeostasis in islets over expressing Pax4 as compared to the T2DM-linked mutant variant Pax4R129W. Pax4 but not Pax4R129W protected islets from thapsigargin-mediated ER-stress apoptosis. Collectively, Pax4 is a critical signaling hub coordinating regulation of distinct molecular pathways resulting in improved b-cell fitness whereas Pax4R129W sensitizes to death under stress. More importantly we highlight potential common pharmacological targets for the treatment of DM. 4 groups of 3 samples each. Primary isolated islets of langerhans from either Pax4/rtTA or Pax4R121W/rtTA mice treated or not with Doxicycline.