SPATIAL AND TEMPORAL ANALYSES OF INTEGRIN AND MUC-1 EXPRESSION IN PORCINE UTERINE EPITHELIUM AND TROPHECTODERM IN-VITRO

The expression of the glycoproteins Muc-1 and integrin subunits (alpha (1), alpha(3), alpha(4), alpha(5), alpha(v), beta(1), and beta(3)), al l of which may be involved in the control of uterine receptivity, was examined in cultured porcine uterine epithelial (pUE) cells. Integrin subunit expression was also determined in trophoblastic vesicles gener ated from Day 12 and Day 15 pig conceptuses. Immunocytochemistry was p erformed on pUE cells cultured on several substrates (glass, serum, fi bronectin, or Matrigel) in DME/F12 medium with 5% charcoal/dextran-str ipped fetal bovine serum either containing no steroids or supplemented with estrogen, progesterone, or estrogen plus progesterone, or in med ium with 5% complete fetal bovine serum. In addition, pUE cells were g rown on Matrigel-coated Millicell filter inserts to facilitate develop ment of structurally and functionally distinct apical and basal domain s (i.e., polarized pUE cells) and were maintained in the same medium w ith supplements. The major findings in this investigation are that 1) Muc-1 and alpha(1), alpha(3), alpha(4), alpha(5), alpha(v), beta(1), a nd beta(3) integrin subunits are expressed on pUE cells in vitro; 2) M uc-1 and several integrin subunits are modulated by steroid hormones i f culture conditions are provided that permit development of cell pola rity; 3) the expression and steroid-induced modulation of Muc-1 and se veral integrin subunits in polarized pUE cells are similar to those de tected in vivo; and 4) the expression of alpha(1), alpha(3), alpha(4), alpha(5), alpha(v), beta(1), and beta(3) integrin subunits by trophob lastic vesicles is identical to their expression on trophectoderm of i ntact conceptuses in vivo. These results suggest that the properties o f polarized pUE cells and trophoblastic vesicles are comparable to tho se of their counterparts in vivo and are, therefore, useful as in vitr o model systems to study conceptus-endometrial interactions during the periimplantation period and the control of uterine receptivity to imp lantation.