Cell surface heparan sulfate proteoglycans are composed of a membrane-associated protein core substituted with a
variable number of heparan sulfate chains. Two different cell surface heparan sulfate proteoglycan families can be
distinguished: (1) the syndecan-like integral membrane proteoglycans (SLIPS), with a core protein spanning the
cytoplasmic membrane, and (2) the glypican-related integral membrane proteoglycans (GRIPS), with a core protein
anchored to the cytoplasmic membrane via a glycosyl phosphatidylinositol.
Princivalle M, et al 2001 reported anticoagulant heparan sulfate proteoglycans expression in the rat ovary peaks in preovulatory granulosa cells.
Ovarian granulosa cells synthesize anticoagulant heparan sulfate proteoglycans (aHSPGs), which bind and activate antithrombin III. To determine if aHSPGs
could contribute to the control of proteolytic activities involved in
follicular development and ovulation, the authors studied the pattern of expression of these proteoglycans during the ovarian cycle. aHSPGs were localized on cells
and tissues by I-125-labeled antithrombin III binding followed by microscopic
autoradiography. Localization of aHSPCs has shown that cultured granulosa
cells, hormonally stimulated by gonadotropins to differentiate in vitro,
up-regulate their synthesis and release of aHSPGs. In vivo, during
gonadotropin-stimulated cycle, aHSPGs are present on granulosa cells of antral
follicles and are strongly labeled in preovulatory follicles. These data
demonstrate that aHSPG expression in the ovarian follicle is hormonally
induced to culminate in preovulatory follicles. Moreover, five heparan sulfate core proteins mRNA (perlecan; syndecan-1, -2, and -4; and
glypican-1) are synthesized by granulosa cells, providing attachment for
anticoagulant heparan sulfate chains on the cell surface and in the
extracellular matrix. These core proteins are constantly expressed during the
cycle, indicating that modulations of aHSPG levels observed in the ovary are
likely controlled at the level of the biosynthesis of anticoagulant heparan
sulfate glycosaminoglycan chains. This expression pattern enables aHSPGs to
focus serine protease inhibitors in the developing follicle to control
proteolysis and fibrin formation at ovulation.