A missense mutation in the membrane trafficking protein αSNAP impairs fertility in female mice

DE PAOLA, M. MATILDE; ARCOS, ALEXIS; CAPPA, ANDREA I.; GARRIDO, FACUNDO M; BATIZ, LUIS F.; MICHAUT, MARCELA A.

La Serena

Workshop; European Molecular Biology Organization (EMBO) Workshop: Actualizations in Membrane Trafficking in Health and Disease; 2016

European Molecular Biology Organization

αSNAP is a ubiquitous and essential component of membrane fusion machinerywhich plays a key role in different aspects of cell biology such as vesicular traffic and exocytosis, and many others like cell polarity, cell division, regulation of ephitelial junctions and apoptosis. Deletion of αSNAP is embryonically lethal, however the spontaneous mutant hyh mice, carrying a missense mutation in Napa gene (M105I), serve as a unique model to study αSNAP function in vivo. We have determined that hyh female have a strongly reduced fertility. Hyh female mice had a significantly decreased ovulation and in vitro fertilization rates compared with wild-type mice. Previously we have determined that αSNAP is required for cortical granules exocytosis (CGE), the primary mechanism in preventing polyspermic fertilization. An increased rate of polyspermy in in vitro fertilization assays was observed in hyh mice, suggesting that M105I mutation impairs CGE. In order to test this hipothesis we nextperformed different CGE assays after in vitro fertilization and partenogenetic activation, which showed that hyh oocytes exhibit a diminished CGE. Interestingly, some hyh MII oocytes showed an abnormal CG pattern, suggesting that αSNAP might have a function in the polarity establishment during oocyte maturation. Furthermore, hyh oocytes presented an altered subcellular αSNAP localization compared with wild type oocytes, as well as an atypical distribution of mitochondrial and Golgi markers. Moreover, cumulus-oocyte complex from hyh female showed a significantly increased of apoptosis, that correlates with a pronounced decreased in αSNAP and N-Cadherin expression in cumulus cells. These results suggest that αSNAP has an important role in the maintenance of N-cadherin-based junctions and survival of cumulus cells. Together, our findings revealed that M105I mutation in αSNAP leads to multifactorial fertility defects in hyh female mice, demonstrating that αSNAP plays an important role in female reproduction.