Study of the participation of the transcription factor TCF7L2 in the mediation of the effects of the hormones progesterone and 17²-estradiol on the pancreatic ² cell in obesity

• Grant number: 23/17143-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: April 01, 2024
• End date: March 31, 2028
• Field of knowledge: Biological Sciences - Physiology - General Physiology
• Principal Investigator: Silvana Auxiliadora Bordin da Silva
• Grantee: Matheus Pedro dos Santos
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 13/07607-8 - OCRC - Obesity and Comorbidities Research Center, AP.CEPID
• Associated scholarship(s): 25/14178-3 - Effects of steroid hormones and fatty acids on the proliferation, insulin secretion and transcriptional activity of TCF7L2 and FOXO in mouse MIN6 and human EndoC-bH1 beta cells., BE.EP.DR

Abstract

The importance of the transcription factor TCF7L2 on the function of beta cells is mainly studied in type 2 diabetes mellitus, and its role in the context of the adaptation of these cells during pregnancy is still poorly explored. Thus, the objective of this work is to evaluate the effect of the gestational hormones progesterone (P4) and 17²-estradiol (E2) on the adaptation of the beta cell via TCF7L2, and the interference of oxidative stress in obesity conditions on this adaptation. In this work, we will use two experimental approaches: 1) in vitro we will use the insulin-secreting cell line MIN6, and 2) in vivo we will use a diet-induced obesity model in female mice of the C57Bl/6. In vitro, MIN6 (control and siRNA.TCF7L2) cells will be treated with palmitate or conditioned medium by isolated adipocyte, and later with P4 and E2, to investigate cell survival (flow cytometry), cell proliferation and oxidative stress (fluorescence spectroscopy), expression of TCF7L2 via the PI3K/AKT/GSK3-beta/beta-catenin pathway and FOXO (Western-blot), competition between TCF7L2 and FOXO for binding to beta-catenin (co- immunoprecipitation), gene expression (qPCR) and glucose-stimulated insulin secretion. In vivo, obese and non-obese female mice will have weight, food intake and glycemic metabolism (GTT and ITT) monitored, and isolated pancreatic islets will be treated with P4 and E2 to assess TCF7L2 and FOXO expression. In the end, we hope to better understand the role of P4 and E2 in the adaptation beta cells during pregnancy, and the molecular mechanisms through which obesity can impair this adaptation and contribute to the pathogenesis of gestational diabetes.