IBIMOL   23987
INSTITUTO DE BIOQUIMICA Y MEDICINA MOLECULAR PROFESOR ALBERTO BOVERIS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Role of USP9x in VMP1-mediated autophagy
Autor/es:
DANIEL GRASSO; FELIPE RENNA; MARIA INES VACCARO; TAMARA ORQUERA
Lugar:
Mar del Plata
Reunión:
Congreso; LXI Reunión Anual de Sociedad Argentina de Investigación Clínica; 2016
Resumen:
The intracellular activation of zymogen granules triggers the acute pancreatitis and the consequence gland self-digestion. Most of acute pancreatitis are self-limited suggesting the importance of the stress response mechanism of pancreas acinar cells. VMP1 is an autophagy protein which is able to induce autophagy even in non-starved condition. Moreover, VMP1 is induced by acute pancreatitis and mediates the zymophagy, a selective autophagy-mediated degradation of zymogen granules. We demonstrated that the deubiquitinase USP9x interacts with VMP1 during zymophagy in acute pancreatitis. The objective of this work is to know the role of USP9x in autophagy process. In HeLa cells, we demonstrate by immunofluorescence (IF) that USP9x responds to starvation as early as 15 minutes with a relocation pattern without changing its expression by western blot. At the basal condition, USP9x is distributed over the whole cytoplasm meanwhile upon starvation it quickly moves to a region rich in lysosomes, marked with Lamp1 fluorescence. USP9x is necessary for autophagosome formation since shRNA-mediated depletion of USP9x inhibits the autophagy, evaluated by LC3 recruitment. USP9x interacts with VMP1 and colocalizes with VMP1 at the reticulum in an area near to the nucleus suggesting its implication in the initiation mechanism of autophagosome formation. USP9x deubiquitinates BECN1, which is an important autophagy protein. By IF, we show the ubiquitination of BECN1 during starvation and its accumulation when it is co-expressed with a ubiquitin molecule without chain formation capability. Consequently, shRNA-mediated depletion of USP9x increases the general ubiquitin signal in the cytoplasm. Our data suggest that USP9x is a novel component of the set of proteins implicated in autophagy, necessary for autphagosome formation and involved in a mechanism where VMP1 and BECN1 are implicated.