Association of KSRP protein with microRNAs related to pancreatic beta cell survival and function

• Grant number: 22/04088-9
• Support Opportunities: Scholarships in Brazil - Doctorate
• Effective date (Start): April 01, 2023
• Effective date (End): July 31, 2026
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Helena Cristina de Lima Barbosa
• Grantee: Juliana Oriel de Oliveira
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

DM1 occurs due to genetic factors that lead to the destruction of beta cells in the pancreas by the immune system, causing a severe deficiency in insulin production. DM2 is characterized by a deficit in insulin production associated with insulin resistance. The production and the secretion of insulin are the main functions of the pancreatic beta cells. After an increase in the plasmatic glucose concentration, the beta cell receives stimulation for insulin synthesis. The secretion of the insulin granule requires cytoskeletal remodeling, depending on Cdc42 and Rac1. The Binding of the vesicle SNARE proteins with SNAREs present in the plasma membrane allows granules to fuse with the membrane, which results in insulin exocytosis. During obesity, with the increasing demand for insulin production, an increase in the mass of beta cells of the pancreatic islets is initially observed. The maintenance of hyperinsulinemia causes beta cell dysfunction, and the progression from obesity to prediabetic state leads to loss of mass of these cells, which is accentuated in the establishment of DM2. Beta-cell apoptosis can be caused either by oxidative stress or endoplasmic reticulum stress. KSRP is a protein that promotes mRNA decay and miRNA maturation. Inhibition or increase in KSRP activity can interfere with the functioning of a series of miRNAs or mRNAs, increasing or decreasing post-transcriptional gene expression, thus directing the function of the cell. The objective of this work is to characterize the function of KSRP protein in pancreatic islets in an in vitro and ex vivo (isolated islet) model of lentiviral knockdown and KSRP overexpression model. After the obtention of KSRP KD models in pancreatic islets, miRNA qPCR Panel will be performed in all the experimental groups; KSRP overexpression will be done by transfecting EGFP-linked KSRP plasmid into INS-1E cells. In KD models for KSRP, KSRP overexpression and INS-1E cells or islets subjected to stressful conditions (high glucose and palmitate exposure), variations in the expression of some microRNAs specifically relevant to the beta cell (let-7a, miR-7, miR-9, miR-21, miR-15a, miR-29a/b, miR-96, miR-124, miR-148, miR-200 and miR-375) are going to be evaluated. This project will contribute to a better understanding of the function of the pancreatic islet and, therefore, the development of more efficient therapeutic strategies for the treatment of diabetes mellitus.