INVESTIGADORES
WEIGEL MUÑOZ Mariana
congresos y reuniones científicas
Título:
INHIBITED PROTEIN TYROSINE PHOSPHORYLATION IN SPERM FROM CRISP1 KNOCK OUT MICE
Autor/es:
MARÍA A. BATTISTONE; JULIETA MALDERA; MARIANA WEIGEL MUÑOZ; JUAN I. ERNESTO; ROMINA PAGOTTO; OMAR P. PIGNATARO; DÉBORA J. COHEN; PATRICIA S. CUASNICU
Lugar:
New Hampshire
Reunión:
Conferencia; Gordon Research Conference; 2011
Resumen:
Mammalian sperm become
competent to fertilize only after undergoing a series of changes that occur
during their transit through the male and female reproductive tracts known as
maturation and capacitation, respectively. Epididymal protein CRISP1 associates
with the dorsal region of rat sperm during epididymal maturation. While a
substantial amount of CRISP1 is released during capacitation suggesting its
role as a decapacitating factor, part of the protein remains on sperm surface
and participates in both sperm-zona pellucida interaction and gamete fusion by
binding to egg-complementary sites. In agreement with this, capacitated sperm
from Crisp1-/- mice
recently generated in our laboratory exhibited a significantly lower ability to
interact with the zona pellucida and the oolema. However, contrary to what it
is expected for a decapacitating factor, tyrosine phosphorylation levels were
significantly lower than in controls suggesting that CRISP1 could play a
regulatory role during capacitation different from that originally expected. Considering
these observations, the aim of the present work was to investigate the molecular mechanisms underlying the lower levels of protein tyrosine phosphorylation observed in CRISP1 knockout sperm.
Based on previous
reports indicating that the presence of CRISP1 during rat sperm capacitation
inhibited protein tyrosine phosphorylation, Crisp1+/-and Crisp1-/- sperm were capacitated in the absence or
presence of 6 µM CRISP1. Results revealed that CRISP1 did not affect protein tyrosine
phosphorylation levels in any of these populations. Since it has been
demonstrated that tyrosine phosphorylation is downstream a cAMP/PKA pathway, we
investigated whether cAMP is involved in the observed reduction of tyrosine
phopshorylation by exposing Crisp1-/-sperm to a cAMP analog (db-cAMP) and a phosphodiesterase inhibitor
(3-isobutyl-1-methylxanthine, IBMX). Results showed that, under these
conditions, there was a reversion in the phosphorylation pattern of Crisp1-/- sperm, supporting
the existence of a lower content of cAMP in mutant sperm. This possibility was
confirmed by the significantly lower cAMP
levels detected in Crisp1-/-
sperm by radioimmunoassay.
Together, these results
indicated that the inhibition of protein tyrosine phosphorylation in sperm
lacking CRISP1 could be attributed to the lower levels of intracellular cAMP
generated during capacitation. Although the molecular mechanisms underlying
cAMP reduction are still unknown, at present we are investigating whether these
observations are related to the reported ion channel regulating ability of CRISP proteins.