vendredi 14 septembre 2018
(14h00) - Fac. de Médecine - Pôle Recherche- Amphi B
Rôle des « sérine/thréonine kinases » dans la cellule bêta pancréatique
\"Serine/Threonine kinases\" role in pancreatic beta cell
Pancreatic beta cell constantly tunes insulin production to meet the body needs. The insulin production adaptation is achieved thanks to highly adaptive beta cell metabolism, signaling, secretory machinery and mass. The beta-cell function and mass plasticity are particularly critical during nutritional, body growth and physiological changes such as obesity, pregnancy and postnatal development of newborn. Functional beta cell demise account for diabetes is one of the leading causes of death worldwide.
In vertebrates, serine-threonine kinases (STKs) drive key signaling pathways for adaptive cells response to the environment. The overall goal of the thesis was to identify the signaling pathways responsible for the development of beta cell mass during postnatal development, pregnancy and obesity. Identification of these signaling pathways may help in understanding the functional beta cell mass demise induced by the diabetogenic environment (e.g oxidized LDL, hyperglycemia, hyperlipidemia, etc.) in diabetic patients. By investigating beta cell mass plasticity in 10 day old neonate rats, we found a significant increase in the expression of Dual Leucine Zipper Kinase (DLK) protein when compared to islets from adult rats. In islets of pups, the increase of DLK expression coincides with a very high proliferative rate of beta cells and activation of \"cJun-amino terminal Kinase 3\" (JNK3) signaling, an STK belonging to mitogen activated protein kinase \"(MAPKs) family. As observed for DLK, in islets of rat pups and mice, the genetic disruption of JNK3 drastically reduces the number of beta cells leading to glucose intolerance. Finally, we also observed that MAPKs link oxidized LDL to beta cell death via mechanisms involving endoplasmic reticulum stress and oxidative stress. Our results show the critical importance of MAPK signaling in controlling beta cell survival and proliferation in response to physiological condition and diabetes.
Unité de recherche : UMR CNRS 8199 éq. 01 (GÉNOMIQUE ET ÉPIGÉNOMIQUE DES MALADIES MÉTABOLIQUES )
directeur de thèse : Amar ABDERRAHMANI