Submitted March 20, 2004
Returned for revision April 13, 2004
Accepted May 19, 2004
Male Reproductive Tract
Compartmentalization of Prion Isoforms Within the
Reproductive Tract of the Ram
Heath Ecroyd ,
Pierre Sarradin ,
Jean-Louis Dacheux ,
and
Jean-Luc Gatti *
* To whom correspondence should be addressed. E-mail: gatti{at}tours.inra.fr.
Abstract
Cellular prion protein (PrpC) is a glycoprotein
usually associated with membranes via its
glycosylphosphatidylinositol (GPI) anchor. The
trans-conformational form of this protein
(PrpSC) is the suggested agent responsible for
transmissible neurodegenerative spongiform
encephalopathies. This protein has been shown on sperm and
in the reproductive fluids of the male. Antibodies
directed against the C-terminal sequence near the
GPI-anchor site, an N-terminal sequence and against the
whole protein showed that the Prp isoforms are
compartmentalized within the reproductive tract of the
ram. Immunoblotting with the three antibodies showed that
the complete protein and both N- and C-terminally
truncated and glycosylated isoforms are present within
cauda epididymal fluid and seminal plasma. Moreover, we
demonstrate that in these fluids, the PrpC
isoforms are both in a soluble state as well as associated
with small membranous vesicles (epididymosomes). We also
report that only one major glycosylated 25kDa C-terminally
truncated PrpC isoform is associated with sperm
from the testis, cauda epididymis and semen, and this form
is also present in the sperm cytoplasmic droplets that are
released during maturation. This C-terminal truncated form
is also associated with membrane lipid rafts present in
the mature sperm suggesting a role for it in the terminal
stages of sperm maturation.
Key words:
Gamete Biology •
Male Reproductive Tract •
Testis •
Epididymis •
Sperm
