Ability of integrins to mediate fertilization, intracellular calcium release, and parthenogenetic development in bovine oocytes

The ability of arginine-glycine-aspartic acid (RGD; a sequence recognized by integrins) or non-RGD-containing peptides to block fertilization, induce intracellular Ca2+ oscillations, and initiate parthenogenetic development in bovine oocytes was investigated. Addition of a soluble RGD peptide during fertilization at concentrations ranging from 10 to 1000 mu g/ml significantly decreased (P < 0.05) fertilization as compared to the in vitro-fertilized controls. The addition of non-RGD peptide had no effect on fertilization. Two intracellular Ca2+ transients 21.5 +/- 1.9 min apart were observed in 56 of 60 oocytes incubated in RGD peptide concentrations ranging from 20 to 1000 mu g/ml. No intracellular Ca2+ transients were observed in medium alone, non-RGD treatment groups or in the RGD peptide at 10 mu g/ml. The percentage of oocytes activated with ionomycin and 6-dimethylaminopurine (63% cleavage and 34% blastocyst development) was significantly higher (P < 0.05) than those activated with the RGD peptide and 6-dimethylaminopurine (35% cleavage and 19% blastocyst development). These groups were significantly higher (P < 0.05) than either peptide alone, 6-dimethylaminopurine alone, or the non-RGD peptide and 6-dimethylaminopurine treatment groups. These data provide evidence that ligation of an integrin on bovine oocytes with a soluble RGD peptide is capable of blocking fertilization, inducing intra-cellular Ca2+ transients, and initiating parthenogenetic development.