INVESTIGADORES
MAYORGA Luis Segundo
congresos y reuniones científicas
Título:
VPS4 is necessary for the acrosome deformation during acrosomal exocitosis in human sperm
Autor/es:
POCOGNONI CA; BELMONTE SA; MAYORGA, L.S.
Reunión:
Congreso; 48º SAIB; 2012
Institución organizadora:
SAIB
Resumen:
The acrosome reaction of human spermatozoa is a complex,
calcium-dependent regulated exocytosis. Fusion between the outer
acrosomal membrane and the cell membrane causes the release of
the acrosomal contents. Preventing the release of calcium from the
acrosome, the exocytic process can be arrested at a stage where
SNARE proteins are assembled in loose trans complexes.
Transmission electron micrographs at this stage showed that the
acrosomes were profusely swollen, with deep invaginations of the
outer acrosomal membrane. These membrane deformations are part
of the mechanism of vesiculation. Invagination of the acrosomal
membrane is topologically equivalent to the formation of
multivesicular bodies in endosomes, a process that depends on the
assembly of the ESCRT complexes. We are exploring the possibility
that the same mechanism is involved in acrosomal exocytosis. A
dominant-negative mutant of VPS4, the ATPase responsible for the
disassembly of the membrane attached ESCRT proteins inhibited
acrosomal exocytosis of permeabilized human spermatozoa.
Moreover, an anti-VPS4 antibody was also inhibitory. TEM images
show abnormal bending of the acrosomal membrane when sperm
were stimulated in the presence of the dominant negative VPS4.
These observations suggest that the deformation of the acrosomal
membrane necessary for acrosomal exocytosis are shaped by an
ESCRT-dependent mechanism