INVESTIGADORES
WEIGEL MUÑOZ Mariana
congresos y reuniones científicas
Título:
SIGNAL TRANSDUCTION PATHWAYS INVOLVED IN RAT SPERM CAPACITATION
Autor/es:
BATTISTONE MA; WEIGEL MUÑOZ M; ERNESTO JI; MALDERA JA; KRAPF D; VISCONTI P; CUASNICÚ PS
Reunión:
Congreso; 37th Annual Meeting American Society of Andrology; 2012
Resumen:
Sperm capacitation relies on an increase in
protein tyrosine phosphorylation mediated by PKA activation. Recent studies
have suggested that Src tyrosine kinase family (SKF) is involved in
capacitation-associated protein tyrosine phosphorylation either direct or indirectly. In order to
elucidate between these two possibilities, we investigated whether SFK is involved
in the signaling events leading to rat sperm capacitation. Western blot results
showed that sperm capacitated in the presence of SFK inhibitors (SU6656 and
SKI606; 50 µM), exhibited low levels of both tyrosine and PKA-substrate
phosphorylation. Based on the described inhibition of ser/thr phosphatases by
SFK, sperm were exposed to a ser/thr phosphatase inhibitor (okadaic acid, OA 10
nM) observing a reversion of the impaired protein phosphorylation produced by
SU6656 and SKI606. However, OA was unable to induce tyrosine phosphorylation in
either non capacitated sperm or sperm capacitated in the presence of the PKA
inhibitor H89. Addition of both a cAMP agonist (dibutyryl cAMP, 5 mM) and a
phosphodiesterase inhibitor (Pentoxifiline, 3mM) did not overcome the
inhibition produced by the SFK inhibitors. In addition to their effect on PKA and protein tyrosine phosphorylation,
SU6656 and SKI606 significantly inhibited capacitated sperm motility (69,4% (control) vs 42,9% (SU6656,
p<0,0001)), vs 34,8% (SKI606, p<0,0001)), acrosome reaction occurrence (32,0% (control) vs 25,2% (SU6656,
p<0,0001, vs 29,4% (SKI606, p<0,009)) and the sperm ability to fuse with zona
pellucida-free oocytes in vitro (96,0% (control) vs 24,3% (SU6656, p<0,0001) vs 20,2% (SKI606,
p<0,001)). These inhibitions were not observed when sperm were exposed to SU6656 or
SKI656 in the presence of OA, indicating that the effect of the SFK inhibitors
involves an up-regulation of the ser/thr phosphatase activity.
Altogether, these results support both the
involvement of SFK in rat sperm capacitation and the existence of two parallel
pathways leading to capacitation: one requiring cAMP/PKA activation, and the
other involving the inactivation of ser/thr phosphatases