Characterization of VAMP 1 and VAMP 2 in mouse oocytes, a potencial role in cortical granules exocytosis

GARRIDO, FACUNDO M; DE PAOLA, M. MATILDE; CAPPA, ANDREA I.; MICHAUT, MARCELA A.

Córdoba

Congreso; LI I Reunión Anual SAIB 201 6; 2016

Sociedad Argentica de Investigación Bioquímica y Biología Molecular

Corticalgranule exocytosis (CGE), also known as cortical reaction, is a secretoryprocess triggered by sperm-oocyte fusion during fertilization. This exocytosisinvolved the membrane fusion of cortical granule, localized in the oocytecortex, and oolema and it is regulated by intracellular calcium. CGE is thoughtto be mediated by SNARE (soluble NSF receptors) complex, whichis formed by SNAP-25, Syntaxin and VAMP. Syntaxin4 and SNAP-25 have beenidentified in mouse egg; however it is unknown if VAMP (vesicle-associated membraneprotein) participates in CGE. The aim of this work was toidentify and characterize the main VAMP isoforms, VAMP1 and VAMP2, involved inexocytosis in other secretory models. RT-PCR assays showed that VAMP1 and VAMP2are expressed in mouse oocytes. Immunofluorescence analysis showed that VAMP1had a cortical localization, while VAMP2 had mainly a cytoplasmic distribution.This result suggested that VAMP1 might be involved in CGE. To confirm thishypothesis we performed a functional assay perturbing the function ofendogenous VAMP1 and VAMP2 by antibody microinjection. Only VAMP1 antibody wasable to inhibit CGE when mouse oocytes were activated parthenogenetically withstrontium chloride. These results confirm that VAMP1 is the VAMP isoforminvolved in CGE. The importance of this work is that we have completed thecharacterization of SNARE complex during membrane fusion in mouse oocytes.