Chorionic expression of heterogeneous products of the PAG (Pregnancy-Associated Glycoprotein) gene family secreted in vitro throughout embryonic and foetal development in the pig.
Porcine PAG (pPAG) are placental products of a multigene family that is strongly expressed in the chorionic epithelium (trophoblast and trophectoderm). The objective of this study was to define a pattern of the pPAG proteins, secreted in vitro by chorionic explants harvested on 16-77 days of pregnancy. Trophoblastic and trophectodermal explants were collected from pregnant (PR) gilts (n = 27) and used for protein in vitro production (8-261 h). Endometrial explants of luteal-phase gilts (E10, n = 4) and pseudopregnant gilts (PsE, n = 2) were used as negative controls for protein immunoblotting. Proteins (PR, E10, PsE) were isolated mainly from incubation media, fractionated, dialysed and separated by SDS-PAGE. Heterogeneous Western blotting with various polyclonal anti-PAG sera raised against bovine or ovine antigens (anti-bPAG, or anti-oPAG) initially identified the pPAG proteins. Such blotting of fractionated chorionic proteins allowed for the isolation of porcine antigens that were employed as immunogens to raise several homologous antisera (anti-pPAG). Crude antisera were adsorbed on endometrial extracts or proteins of non-PR pigs, to remove non-relevant antibodies. The patterns of pPAG proteins secreted in vitro varied throughout pregnancy (35-72 kDa). During implantation, approximately 43 kDa (Day 16) or approximately 68.1 kDa (Days 17-25) pPAG proteins were detected. During placentation and as pregnancy advanced (Days 31-77), approximately 72.3 kDa pPAG proteins were observed. The secretions of parallel multiple smaller proteins (35.4-47.2 kDa), presumably, as forms of processed pPAG precursors, increased with the progress of gestation. In conclusion, the pPAG protein family plays a very important role during implantation, placenta formation and embryonic/foetal development in the pig.
Szafranska
Bozena
B
Department of Animal Physiology, Faculty of Biology, University of Warmia and Mazury, 10-719 Olsztyn-Kortowo, Oczapowskiego Str 1A/222, Poland. szafran@moskit.uwm.edu.pl
Panasiewicz
Grzegorz
G
Majewska
Marta
M
Beckers
Jean-Francois
JF
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D015153:Blotting, Western / Q000662:veterinary; D002823:Chorion / Q000201:enzymology / Q000378:metabolism*; D003429:Cross Reactions; D046508:Culture Techniques; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D007106:Immune Sera / Q000276:immunology / Q000302:isolation & purification; D005810:Multigene Family / Q000235:genetics; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D011270:Pregnancy, Animal / Q000502:physiology*; D013552:Swine / Q000196:embryology*; D014327:Trophoblasts / Q000378:metabolism
D007106:Immune Sera; D011257:Pregnancy Proteins; D016282:Aspartic Acid Endopeptidases; C094766:pregnancy-associated glycoprotein 1