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 b y integrins) or non-RGD-containing peptides to block fertilization, induce intracellular Ca2+ oscillations, and initiate parthenogenetic development i n bovine oocytes was investigated. Addition of a soluble RGD peptide during fertilization at concentrations ranging from 10 to 1000 mu g/ml significan tly decreased (P < 0.05) fertilization as compared to the in vitro-fertiliz ed 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 t o 1000 mu g/ml. No intracellular Ca2+ transients were observed in medium al one, non-RGD treatment groups or in the RGD peptide at 10 mu g/ml. The perc entage of oocytes activated with ionomycin and 6-dimethylaminopurine (63% c leavage and 34% blastocyst development) was significantly higher (P < 0.05) than those activated with the RGD peptide and 6-dimethylaminopurine (35% c leavage and 19% blastocyst development). These groups were significantly hi gher (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 solu ble RGD peptide is capable of blocking fertilization, inducing intra-cellul ar Ca2+ transients, and initiating parthenogenetic development.