Subprojeto 6 – Role of gap junction-mediated cell coupling in the insulin secretion process during animal development and in diabetes pathogenesis

Participantes: Carla B. Collares-Buzato

GJ-mediated intercellular communication has been found to maintain tissue/organ homeostasis, and some connexin mutations have been clearly related to human diseases. The islet of Langerhans is considered the functional unit for insulin secretion and glucose homeostasis. In vivo and in vitro studies have demonstrated that GJ-mediated cell coupling is crucial for an adequate biosynthesis, storage and release of insulin by B-cells. Experimental conditions that result in increase in cell coupling and/or in the number of GJ channels lead to an augment of biosynthesis and secretion of insulin. Conversely, pharmacological blockage or rupture of the GJ channels induce impairment of the insulin secretory process. It is well known that fetal and neonatal pancreatic islets present a lower insulin secretory response as compared to adult islets. The nature of the similarities between the perinatal pattern of insulin secretion and the pre-diabetic state is not fully understood. Additionally, it has not been established the role of the GJ-mediated cell coupling on the insulin secretory process during animal development and in the diabetes pathogenesis. Recently, we have demonstrated alterations to the connexin expression and cellular distribution in pancreatic islets of animal models of B-cell differentiation/maturation and type II diabetes. The aim of this project is to investigate the functional role of GJ in B-cells and intact islets of these animal models using FRAP (Fluorescence Recovery After Photobleaching) assay. This technique has been validated as a reliable technique to analyze functional GJ-mediated communication, because of several advantages that it offers over alternative techniques. By using different GJ-permeant molecules, with different charges and molecular weights, we intend to measure the degree of B-cell-B-cell coupling in intact islets isolated from animals at different ages (from embryonic to the adult stages) and diabetic ones.