Effect of early treatment with insulin and the role of Grb2 and downstream signaling on pancreatic beta cell function: possible protective action on endoplasmic reticulum stress

• Grant number: 18/19979-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2019
• End date: December 31, 2019
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Helena Cristina de Lima Barbosa
• Grantee: Marina dos Santos Carvalho
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Early treatment with insulin is an alternative therapy for patients newly diagnosed with type 2 diabetes mellitus that has been tested in several clinical trials. Patients undergoing treatment rapidly achieve normoglycemia and have good glycemic control over the long term. This improvement in DM2 is possibly due to the recovery and maintenance of pancreatic beta cell function, a cell that during the development of DM2 may have mass reduction and its secretory insulin capacity. Because they are clinical trials, it is not clear what the mechanisms are activated in the beta cell, by the early treatment with insulin for this improvement. Our hypothesis is that, at least in part, this improvement is due to the reversal of the endoplasmic reticulum (ER) stress, one of the mechanisms related to this decline in insular function. The loss of homeostasis during the stress of ER activates the UPR, unfolded protein response, which may compromise insulin secretion and lead to apoptosis. In the present project we propose to evaluate the role of Grb2 and FAK as possible mediators of insulin signaling. The Grb2 adapter protein has been shown to be important in signaling pathways for cell growth, proliferation and survival. While its molecular partner FAK has important role on mechanisms related to cell survival, migration and growth. To assess this hypothesis, INS-1E beta cells will be treated with CPA for induction to the stress state of ER and subsequently treated with insulin. Then, the UPR components will be evaluated by Western blotting and qPCR. To evaluate the possible participation of the Grb2-FAK pathway, Grb2 will have its reduced expression with the use of specific siRNAs, and then the same analyzes of the UPR components will be made. Furthermore, in the INS-1E model treated with siRNAs against Grb2, the phosphorylation at two sites of the FAK will be evaluated through Western Blotting. In this way, this project will contribute to the elucidation of treatment mechanisms in use in patients, in order to make it more effective.