trous cycle and preg nancy and FGFR2IIIb is expressed by uterine epithelia and conceptus trophectoderm. E2 secreted by pig con ceptuses increases FGF7 gene expression in pigs, but only right after P4 has suppressed expression of PGR by uterine GANT61 epi thelia. In turn, FGF7 increases cell proliferation, the abun dance GANT61 of phosphorylated FGFR2IIIb, the MAPK cascade and also the expression of plasminogen activator urokinase, a marker for trophectoderm cell differentiation. From about Day 20 of pregnancy, FGF7 is expressed by uterine GE in pigs in response to P4 and is presumed to continue to affect uterine epithelia and conceptus devel opment. Gene expression by cells with the pig uterus during pregnancy and in response to exogenous E2 and/or intra uterine injections of pig conceptus secretory proteins containing IFNG and IFND have been reported.
The elevated secretion of E2 among Days 15 and 30 of pregnancy also increases expression of endometrial receptors for PRL which is associated with increases in uterine secretory activity and uterine blood SC144 flow. Secreted phosphoprotein 1 and pregnancy Sheep SPP1 is an acidic phosphorylated glycoprotein compo nent with the ECM in epithelia and secretions of many tis sues, including the oviduct, uterus, trophoblast and placenta. SPP1 binds to integrin heterodimers in cluding ITGAV ITGB3, ITGAV ITGB1, ITGAV ITGB5, and ITGA4 ITGB1 heterodimers via its arginine glycine aspartic acid sequence to promote cell adhesion, spreading and migration, also as calcium transport and phosphotidylinositol 3 kinase activity.
SPP1 increases in abundance in uterine flushings from pregnant ewes among Days 11 to 17 when adherence and attachment of conceptuses to uterine LE occurs. SPP1 then binds integrin heterodimers expressed by trophectoderm and uterus to 1 stimulate modifications in morphology of conceptus trophectoderm, and 2 induce adhesion among uterine LE and Protein precursor trophectoderm essen tial for implantation and placentation. Even though SPP1 mRNA increases only in GE of pregnant ewes, SPP1 protein is localized on the apical aspect of uterine LE, GE and conceptus trophectoderm. Progesterone induces expression of SPP1 in uterine GE that lack PGR, there fore, the effects of P4 are assumed to be mediated by SC144 a P4 induced stromal cell derived growth element for example FGF10 and/or HGF in ewes. Administration of both E2 and P4 induces PGR expression in endometrial GE that is definitely followed by a dramatic reduce in expression of SPP1.
Pigs In pigs, SPP1 mRNA is initially detected in discrete regions of GANT61 uterine LE juxtaposed to the conceptus just prior to implantation SC144 on Day 13. Expression of SPP1 is induced by E2 from conceptuses beginning on Days 11 and 12 to signal pregnancy recognition and expression expands to the whole uterine LE by Day 20 when firm adhesion of conceptus trophectoderm to uterine LE is established. SPP1 mRNA is not present in pig conceptuses. In contrast, SPP1 protein is abundant along the apical surface of uterine LE and trophectoderm cells along the whole maternal placental interface during pregnancy. At this interface there is also expres sion of numerous integrin subunits that potentially type heterodimeric receptors for SPP1 including ITGAV ITGB3, ITGAV ITGB1, ITGAV ITGB5, and ITGA4 ITGB1.
The interaction among the integrin het erodimers and SPP1 most likely induces modifications in morph ology of trophectoderm and mediates adhesion among trophectoderm and uterine LE vital for implantation and placentation. Employing a porcine trophectoderm cell line and major porcine uterine epithelial cells, it was determined that pTr2 and pUE integrins bind SPP1 dir ectly. GANT61 The integrins involved had been identified as ITGAV and ITGB6 on pTr2 cells and ITGAV and ITGB3 on pUE cells. Employing these cell lines, it was also deter mined that the RGD sequence in SPP1 is needed for dose and cation dependent attachment, also as mi gration of pTr2 cells and pUE cells. SPP1 induced migration of pTr2 cells was blocked with blebbistatin, an inhibitor of myosin II mediated motor activity.
Further, making use of SPP1 coated microspheres and pTr2 cells, it was determined that co localization of ITGAV integrin sub unit and talin had been associated with assembly of focal adhesions at the apical domain of pTr2 cells. These outcomes indicate that SPP1 stimulates migration and at tachment of pig SC144 trophectoderm by stimulating force driven, integrin mediated, focal adhesion assembly and haptotactic migration needed for conceptus elongation and implantation. Interestingly, ITGAV ITGB6 on conceptus trophectoderm binds discretely to only three ECM proteins, every of which is expressed prominently at the conceptus endometrial interface of pigs, namely SPP1, fibronectin and also the latency associated peptide of TGFB. Employing porcine chorioallantoic membranes placed in Ussing chambers, we lately reported that SPP1 enhanced placental transport of ions. Particularly, addition of placenta conditioned medium that contained SPP1 elevated the transepithelial voltage wi
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