Submission Number: LAU-4-17-2

Abstract Number: 444

ACTIVATION OF CONCEPTUS AND MATERNAL INTEGRINS BY TRANSFORMING GROWTH FACTOR BETA LATENCY ASSOCIATED PEPTIDE.

Laurie A Jaeger*, Robert C Burghardt*, Greg A Johnson* and Fuller W Bazer*

Center for Animal Biotechnology and Genomics, Texas A&M University, College Station, TX ¹

Abstract:
We have previously determined that amounts of active transforming growth factor beta (TGF) increase during the peri-implantation phase of porcine pregnancy. We hypothesize that, in addition to direct effects of the TGFs themselves on the implantation process, the latency associated peptide (LAP) that is released upon TGF1 activation also plays a role in establishing adhesion between conceptus trophoblast (Tr) and uterine luminal epithelium (ULE) by functioning as an RGD-containing ligand for conceptus and maternal integrins. The objective of this study was to determine if interaction of Tr and/or ULE integrins with LAP results in integrin activation. Functional activation of integrins at Tr and ULE apical surfaces was monitored using an extracellular matrix (ECM)-coated bead assay which induces massive cytoskeletal reorganization and aggregation of signaling molecules into "focal adhesions" at sites of integrin activation by RGD-containing ECM proteins. Cultures of porcine Tr (pTr), pULE, ovine Tr (oTr) and immortalized oULE were incubated for 1h with polystyrene beads that were coated with LAP, fibronectin (FN; positive control), or poly-L-lysine (PL; negative control). Distribution of talin, a cytoskeletal protein that aggregates at focal adhesions, was determined using optical slices of digital immunofluorescence images of Tr and ULE. Talin aggregation was detected at interfaces of pTr, pULE, oTr, and oULE apical cell surfaces and FN- or LAP-coated beads; PL-coated beads did not induce talin aggregation. Western blot of uterine luminal flushings and immunofluorescence analysis of endometrium and conceptus Tr confirmed the presence of LAP at the pre-implantation porcine conceptus-maternal interface. These data indicate LAP- and FN-induced activation of both Tr and ULE integrins and suggest that these ECM-integrin interactions may be components of the implantation process during epitheliochorial placentation. Supported by USDA-NRI 98-35203-6223, USDA 98-35203-6337, and NIH P30 ES09106.

Keywords: integrin TGF porcine ovine implantation

This abstract is being presented at: 1:45 PM in session:
SESSION 18: IMPLANTATION AND EARLY DEVELOPMENT