INVESTIGADORES
MONCLUS Maria De Los Angeles
artículos
Título:
Progesterone Receptor Avaibility in Mouse Spermatozoa During Epididymal Transit and Capacitation: Ligand Blot Detection of Progesterone Binding Protein
Autor/es:
PIETROBON ELISA OLIVIA; MONCLUS MARIA DE LOS ANGELES; ALBERDI AANTONIO JOSE; FORNÉS MIGUEL WALTER
Revista:
JOURNAL OF ANDROLOGY
Editorial:
High Wire Press
Referencias:
Lugar: Standford; Año: 2003 vol. Jul p. 612 - 620
ISSN:
0196-3635
Resumen:
The goals
of the present study were to determine the availability of
progesterone (P4) receptor (P4r) in mouse sperm during maturation and
capacitation and to make the first steps toward a characterization of
P4r. It has been proposed that P4 is able to induce an acrosomal reaction
(AR) by using a membrane P4r. This induction was verified in sperm
isolated from the cauda epididymis (fully mature) when incubated in
specific conditions that capacitate sperm. First, we set up the
conditions in our laboratory to induce an AR in mature and
capacitated sperm triggered by P4 that was detected by a
chlortetracycline (CTC) assay. Then, we examined sperm isolated from
the caput epididymis (immature) incubated under conditions that
support cauda sperm capacitation and found that the AR could not be
detected. Moreover, P4 was unable to induce the AR when it was
applied to sperm isolated from either region and incubated under
conditions that did not support capacitation. These results can be
explained by changes in P4r availability. A suitable marker for P4r
is the gold (Au)-P4 complex. This marker shows a binding capacity
that can be visualized directly by electron microscopy (EM) and
indirectly by silver-enhanced methods with light microscopy. The
Au-P4 complex was localized in capacitated cauda sperm at the dorsal
edge of the head. Using these techniques, we observed a significant
decrease in both noncapacitated cauda sperm and caput sperm (whether
incubated in capacitating media or not). Genomic P4r could be
responsible for the signal detected, but antibodies against the P4
nuclear receptor did not recognize any sites in the sperm by
immunostaining methodology. Instead, a 44-kd protein band was
detected in the sperm by a ligand blot assay. In conclusion, P4
promotes the AR in capacitated cauda sperm but is unable to do so in
noncapacitated or immature sperm because the availability of P4r
increases during epididymal transit and after capacitation. The P4r
responsible for this behavior is different from a classical nuclear receptoronthe basis of the immunostaining resultsand is probably a
protein close to 44 kdon the basis of the ligand assay results.
Key
words: Acrosome reaction, sperm, maturation