Acrosomal reaction in mouse sperm: signal transduction that responds to progesterone.

PIETROBON EO1, SORIA M, DOMÍNGUEZ LA, MONCLUS MDE L, FORNÉS MW.; DOMINGUEZ L; ELISA O. PIETROBON; MONCLUS M; FORNES M

mendoza

Congreso; (Sociedad de Biología de Cuyo) 20th Annual Scientific Meeting In memoriam Prof. Alberto Binia; 2002

(Sociedad de Biología de Cuyo)

Mouse sperm acrosomal reaction (AR) is a highly regulated processtriggered by specific signals of zona pellucida proteins througha non well characterized signal transduction pathway. Progesterone(P) can inititate the cascade leading to the AR. Our previouswork suggested that the sequential activation of G proteins (G) →phospholipase A2 (PLA2) → increase in intracellular Ca2+ (iCa2+)promotes AR. It is possible that this cascade is activated by P inmouse sperm; other phospholipase could also be involved. Usingspecific inhibitors, GDPβ ( for G), ONO-RS 082 (for PLA2) andneomycin (for PLC,) or mimetics, GTPγ (G), PMA or imipramine(phorbol ester for PLC) and arachidonic acid (PLA2 ) alone or incombination, their participation in AR was tested both in the presenceand in the abscence of P. Percentages of reacted sperm wereobtained by the chlortetracycline stain technique. FURA-AM ? aniCa2+ fluorescence marker ? was determined by spectrofluorometry.P (10 µM) was used to trigger AR. Sperm was capacited inHMB medimu for 60 min. Mimetics of both phospholipases wereinvolved in promoting AR, as well as GTPγs. Conversely, phospholipaseor G inhibitors blocked AR. But, both are independent.An iCa2+ increase was detected follow activation of PLC or PLA2.These results suggest that P activates G, and simultaneously andindependently G activates PLC or PLA2. Both promote an iCa2+increase that finally leads to AR