Monday, August 2, 2004
10:30 AM–12:30 PM
(237) SPECIFIC INTEGRIN SUBUNITS PRESENT ON THE VITELLINE MEMBRANE OF BOVINE OOCYTES.
Pate, Barry1, Li, Guang-Peng1, Aston, Kenneth 1, Bunch, Thomas1, Campbell, Kenneth1, Hammon, Doug1, Rickords, Lee1, White, Kenneth1, 1 Utah State University, Logan, UT
ABSTRACT- Integrin molecules are cell surface adhesion receptors which form a family of heterodimeric transmembrane glycoproteins. Integrins facilitate attachment of cells to the extra-cellular matrix (ECM), often binding the RGD tri-peptide motif, thus facilitating cell migration, mediating cell-cell adhesion, linking the ECM with cytoskeletal elements, and acting as signaling molecules. Adhesion activates signaling mechanisms that regulate integrin function, cytoskeletal assembly, cell behavior, and protein synthesis. Evidence for the presence of integrin or integrin-like molecules on the surface of oocytes has been found in many species, including hamsters, humans, mice, pigs and cattle. The present study was conducted to determine the presence of specific integrin subunits on the bovine oocyte. Immunofluorescence was used to determine the presence of integrin and subunits on the surface of bovine oocytes using a panel of monoclonal antibodies (mAb) specific for L, M, X, V, 2, 4, 6, 1, 2, and 3. Zonae were removed from IVM bovine oocytes and the denuded oocytes were incubated with each of the primary antibodies, washed, and then labeled with secondary antibody. Oocytes were then washed again and imaged using a confocal microscope to detect specific fluorescence of any integrin subunits present on the plasma membrane. Confocal microscopy indicated the presence of 2, 4, 6, V, 1, and 3 integrin subunits on the plasma membrane of bovine oocytes. Individual subunits were detected using different mAbs directed against the same subunit to provide greater certainty of the presence of each integrin subunit. The ability of a common integrin-binding motif (RGD) to mediate intracellular calcium transients and parthenogenetic development to blastocyst in bovine oocytes has been previously demonstrated. The presence of these integrin subunits on the oocyte vitelline membrane supports the hypothesis that sperm-oocyte interactions in the bovine are mediated by integrins. Further characterization of these integrin subunits and any specific interactions they have with sperm is ongoing.
KEY WORDS: oocyte , fertilization, integrin, bovine