PARENT SESSION
GAMETE BIOLOGY AND GAMETOGENESIS - B

Tuesday, August 3, 2004
10:30 AM–12:30 PM
Buchanan Courtyard

(416) SPERM AKAPS IN THE TRIANGULAR PART OF THE EQUATORIAL SUBDOMAIN OF BOAR SPERM DURING CAPACITATION, HYPERACTIVATION, AND INDUCED ACROSOMAL REACTION.

Kyselova, Vendula¹, Peknicova, Jana¹, ¹ Institute of Molecular Genetics, Prague, Czech Republic

ABSTRACT- The A Kinase Anchoring Proteins (AKAPs) represent a functionally related family of regulatory proteins containing a conserved PKA binding domain and unique targeting sequence that directs the PKA-AKAP complex to subcellular structures. In our laboratory we have generated monoclonal antibody Hs-AKAP against the C-terminus of a family of sperm AKAPs (AKAP4, AKAP3 and AKAP220). In capacitated boar sperm head we found AKAPs in the Tx-100-insoluble fraction, suggesting that sperm AKAPs are tethered to the cytoskeleton. In addition, tyrosine phosphorylation of these proteins was found. According to immunofluorescence, during capacitation we detected AKAPs uniquely in the triangular part of the equatorial subdomain of boar sperm head. AKAPs and phosphotyrosine (pY) or class III –tubulin colocalized in this triangular part of the equatorial subdomain. The colocalization of AKAPs and pY was also found in the acrosome, neck and entire sperm tail, and AKAPs and class III –tubulin in the neck and principal piece of the tail of capacitated sperm. After induction of acrosomal reaction by ionophore A23187 the number of equatorial subdomains labeled by Hs-AKAP monoclonal antibody significantly decreased. This decrease was not as significant as in the acrosome. These results sugest that sperm AKAPs are tyrosine phosphorylated in the equatorial subdomain and in complexes with the cytoskeleton during capacitation and hyperactivation. In binding experiments we showed that sperm AKAPs do not primarily serve for binding sperm to the oocyte, but could play a role in further steps of fertilization. This work was supported by grant No. 204/02/1373 from the GA CR and grant No. NJ/7463-3 from the IGA MH CR.

KEY WORDS: sperm, hyperactivation, AKAP, capacitation