Effect of Conceptus on Transforming Growth Factor (TGF) β1 mRNA Expression and Protein Concentration in the Porcine Endometrium— <i>In Vivo</i> and <i>In Vitro</i> Studies

Abstract

Transforming growth factor (TGF) β and its receptors are expressed at the conceptus-maternal interface during early pregnancy in the pig. The present studies were conducted to examine: (1) the effect of conceptus products on TGFβ1 mRNA expression and protein concentration in the porcine endometrium using in vivo and in vitro models, and (2) the effect of TGFβ1 on proliferation of porcine trophoblast cells in vitro. During in vivo experiments, gilts with one surgically detached uterine horn were slaughtered on days 11 or 14 of the estrous cycle and pregnancy. For in vitro studies, endometrial explants and luminal epithelial (LE) cells co-cultured with stromal (ST) cells were treated with conceptus-exposed medium (CEM). Moreover, porcine trophoblast cells were treated with TGFβ1, and the number of viable cells was measured. On day 11, the presence of conceptuses had no effect on TGFβ1 mRNA expression, but decreased the TGFβ1 protein concentration in the connected uterine horn compared with the detached uterine horn. In contrast to day 11, on day 14 after estrus, TGFβ1 mRNA expression and protein content in the endometrium collected from the gravid uterine horn were greater when compared with the contralateral uterine horn. The treatment of endometrial slices with CEM resulted in greater TGFβ1 mRNA expression and protein secretion. LE cells responded to CEM with an increased TGFβ1 mRNA level. Moreover, TGFβ1 stimulated the proliferation of day 14 trophoblast cells. In summary, porcine conceptuses may regulate TGFβ1 synthesis in the endometrium at the time of implantation. TGFβ1, in turn, may promote conceptus development by increasing the proliferation of trophoblast cells.

Prostaglandin F2α promotes angiogenesis and embryo–maternal interactions during implantation

“…It is also an important cytokine regulating conceptus development and implantation in pigs (Blitek et al 2013). TGFβ stimulates fibronectin synthesis by porcine trophoblast as well as trophoblast cell adhesion to this protein (Jaeger et al 2005).…”

Embryo‐maternal dialogue during pregnancy establishment and implantation in the pig

“…On Day 14 of pregnancy, TGFB1 expression was higher in the endometrium of the gravid compared to the non‐gravid uterine horn. Moreover, conceptus‐conditioned culture medium increases TGFB1 mRNA content in the luminal epithelium (Blitek, Morawska‐Pucinska, Szymanska, Kiewisz, & Waclawik, ). Identification of phosphorylated SMAD2/3 in the conceptus and uterine tissues indicate the activation of TGFB‐dependent intracellular signaling, which possibly fosters conceptus development and attachment (Massuto et al, ).…”

“…Identification of phosphorylated SMAD2/3 in the conceptus and uterine tissues indicate the activation of TGFB‐dependent intracellular signaling, which possibly fosters conceptus development and attachment (Massuto et al, ). Importantly, TGFB1 not only enhances the expression of extracellular matrix proteins and activates integrin receptors (Jaeger et al, ), but also stimulates proliferation of trophoblast cells (Blitek et al, ).…”

Cytokines from the pig conceptus: roles in conceptus development in pigs

“…During the early peri-implantation period, the endometrium increases the release of epidermal growth factor (EGF) [ 34 – 37 ], insulin-like growth factor-1 (IGF-1) [ 38 – 42 ], FGF7 [ 43 , 44 ], vascular endothelial growth factor (VEGF) [ 45 – 47 ], interleukin 6 (IL6) [ 48 – 50 ], transforming growth factor beta (TGFB) [ 51 – 53 ], and leukemia inhibitory factor (LIF) [ 48 – 50 ] for which the developing conceptus trophectoderm expresses EGF-receptor (EGFR) [ 36 ], IGF1R [ 54 ], FGFR2 [ 55 ], VEGFR1 and 2 [ 45 , 47 ], IL6R [ 50 ], TGFBR1 and 2 [ 52 ], and LIFR [ 50 ]. The increased endometrial release of EGF, FGF7, LIF, and IGF-1 are enhanced in the epithelium during the period of conceptus elongation and estrogen release [ 42 , 44 , 50 , 51 , 55 ]. Receptor activation by many of the uterine secreted factors has been shown to occur through multiple signaling pathways such as phosphatidylinositol 3-kinase (P13K)/AKT1 and mitogen-activated protein kinase ERK1/2MAPK [ 36 , 47 , 54 ] which are cell signaling pathways linked to stimulating trophectoderm proliferation, migration and survival.…”