Calcium/Calmodulin kinase II and its participation in the capacitation of Chinchilla lanigera spermatozoa

APARICIO, JUAN DANIEL; GRAMAJO BÜHLER, MARÍA CECILIA; BÜHLER, MARTA INÉS

Encuentro; XXIX ANNUAL SCIENTIFIC MEETING - TUCUMAN BIOLOGY ASSOCIATION; 2012

The sperm of Chinchilla lanigera acquire their fertilizing capacity through the capacitation process (CP). CP changes the pattern of motility, enables the acrosome reaction (AR), and selects a subpopulation of gametes capable of fertilizing the egg. An important factor during CP is the increase in [Ca2+] i that activates various cell signaling pathways. In some species the calcium/calmodulin (Ca/CaM)-dependent protein kinase and Ca/CaM (CaMKII) play a major role in membrane fusion. The objective of this work is to determine the role of the Ca/calmodulin-CaMKII pathway in the membrane events occurring during CP in epididymal sperm. Sperm were obtained by puncturing the cauda epididymis of sexually mature males. The samples were washed by centrifugation. The suspension was divided into six fractions. Four of them were preincubated with different concentrations of KN93, a CaMKII inhibitor, for 30 min. and incubated in Tyrode capacitation medium for 4 hs. The other two fractions were used as control. CP was evaluated by the occurrence of AR induced by progesterone evidenced by Papanicolaou stain. The results indicate that KN93 (5μM) produces an inhibition in AR. This effect is maintained without signifi cant differences at higher concentrations (10, 20 and 40 mM). The reversibility assay indicated no cytotoxicity at the doses used. Blocking of CaMKII has an inhibitory effect on CP, suggesting that this enzyme plays a regulatory role in the events involved in the CP.