Mechanisms involved in Chromaffin Cell Rapid Endocytosis

ANA VERÓNICA BELINGHERI; FERNANDO D. MARENGO

Huerta Grande (Cordoba)

Congreso; Reunion Anual de la Sociedad Argentina de Investigacion en Neurociencia; 2011

Sociedad Argentina de Investigacion en Neurociencia

Endocytosis is critical for maintaining membrane homeostasis and secretion reliability in neuroendocrine cells. Chromaffin cell rapid endocytosis (RE) is Ca2+ dependent and presents two kinetic components, R1<1s and R2~8s. In this work we started to study which endocitotic mechanism (kiss and run, bulk, clathrin dependent endocytosis (CDE)) are associated to R1 and/or R2 components. We used drugs against different steps of endocytosis and measured cell membrane capacitance by the patch clamp technique. Dynasore (80uM), a non competitive inhibitor of dinamin (a GTPase involved in the closure of fission pore in kiss and run and CDE) partially inhibited RE (by 50%). Although it is classically assumed that CDE is a slow process, it was recently described a CDE in beta cells with a time evolution similar to our R2 component. Considering this fact, we used chlorpromazine 15uM, a drug that interferes with the assembly-disassembly of clathrin in the coated pits. RE was partially inhibited (by 60%), R2 component was 3.5 times slower and surprisingly R1 component was almost lost (it appeared in the 15% of the cases, while in control cells in the 75%). These preliminary results suggest that a significant portion of RE in chromaffin cells might be accounted by a clathrin dependent process.