Estudio de la exposicion de fosfatidilserina en ovocitos fertilizados de ratón

CURIA A; ERNESTO JI; CUASNICU PS; COHEN D.J

Buenos Aires

Jornada; XII Jornadas Multidisciplinarias de la Sociedad Argentina de Biología; 2010

Sociedad Argentina de Biología

We have recently shown that sperm entry induces in eggs a transient exposure of phosphatidylserine (PS), a phospholipid asimatrically distributed to the inner leaflet of the lipid bilayer. The balance of PS in the plasma membrane is maintained by two enzymes scramblases which tranlocate phospholipids in both directions allowing the exposure of PS, and flipasses which maintain the asymmetry by actively internalizing PS. In the present work,we have characterized the PS-exposure kinetic in fertilized eggs, and analyzed the expression in eggs of the different enzymes involved in PS mobilization. Quantification of the labeling for fluoresceinated Anexin-5, protein that specifically binds to PS, in the whole egg surface, showed that the highest fluorescensce was observed 1 h post-insemination and then decreased progressively. However, when the intensity was measured only in the labelled regions of the egg, we observed that it did not change along time. RT-PCR analysis showed the expression in eggs of two scramblases PLSCR1 and PLSCR3 and two flipasses (ATP8A1 y ATP8A2.However, the incubation of eggs with the flipasses inhibitor prior to insemination, did not affect the PS exposure patterns. Altogether,these results indicate the presence of scramblases and flipasses in the oocyte, suggesting that these enzymes could regulate the kinetics of PS exposure in fertilized eggs.