The
Arg-Gly-Asp peptide (RGD), contained in several
extracellular matrix proteins such as
fibronectin,
laminin,
vitronectin, and
collagen, is a tripeptide that plays a role as a recognition sequence in many cell-to-cell and cell-to-matrix adhesion mechanisms, through its interaction with several receptors of the
integrin family. We previously described the ability of the oolemma of hamster oocytes to bind
GRGDTP coupled to the surface of activated immunobeads and demonstrated that RGD-containing
oligopeptides inhibit the adhesion of human and hamster spermatozoa to
zona-free hamster oocytes and their subsequent penetration. In the present experiments, we show, utilizing immunobeads coated with an RGD-containing
peptide (PepTiteTM 2000), that the oolemma of unfertilized human eggs is also able to recognize this adhesion sequence. The binding of PepTiteTM 2000-coated immunobeads to the oolemma was inhibited by the
oligopeptide GRGDTP as well as by
fibronectin and
laminin. When immunobeads were prepared with a PepTiteTM concentration of 10 micrograms/ml,
GRGDTP 150 micrograms/ml,
laminin 80 micrograms/ml, and
fibronectin 60 micrograms/ml inhibited bead rosetting on the egg surface. These data suggest that a specific binding moiety for RGD is present on the human egg surface. The binding of
fibronectin to the oolemma was also demonstrated by the rosetting of immunobeads coupled with antifibronectin antibody to human oocytes after their exposure to 1 mg/ml free
fibronectin. Such binding of
fibronectin to the oolemma could be inhibited by coincubation with a
monoclonal antibody directed against the cell adhesion fragment of
fibronectin.(ABSTRACT TRUNCATED AT 250 WORDS)