Signal transducer and activator of transcription 3 (Stat3) expression and activation in rat uterus during early pregnancy

Abstract

Signal transducer and activator of transcription 3 (Stat3), a member of the Stat family, is specifically activated during mouse embryo implantation. The aim of this study was to investigate the expression, activation and regulation of Stat3 in rat uterus during early pregnancy, pseudopregnancy, delayed implantation and artificial decidualization. Stat3 mRNA was highly expressed in the luminal epithelium on day 5 and in the luminal epithelium and underlying stromal cells at implantation sites on day 6 of pregnancy. There was a strong level of Stat3 protein expression and phosphorylation in the stromal cells near the lumen and in the luminal epithelium on day 5 of pregnancy, which was similar to day 5 of pseudopregnancy. In the afternoon of day 6, the strong level of Stat3 phosphorylation was detected only in the luminal epithelium. Stat3 was highly expressed and activated in the decidual cells from days 7 to 9 of pregnancy and under artificial decidualization in the present study. Our results suggest that the strong level of Stat3 activation in the luminal epithelium and underlying stromal cells during the preimplantation period may be important for establishing uterine receptivity as in mice, and the high level of Stat3 expression and activation in decidual cells may play a role during decidualization.

Cloning of porcine signal transducer and activator of transcription 3 cDNA and its expression in reproductive tissues

“…Our findings that Stat3 is expressed at high levels in the reproductive tissues suggest that Stat3 may play a role in the regulation of reproductive function. The presence of Stat3 protein in the mucosal folds of the oviduct, and the endometrium of the uterus is consistent with the previously reported role of Stat3 during early embryogenesis (Takeda et al 1997), implantation and development (Teng et al 2004a(Teng et al , 2004b. It is possible that the expression of Stat3 in the oviduct and uterus is involved in upregulating the expression of genes that are important for early embryo development and implantation.…”

“…Stat3 is essential during embryogenesis, given that disruption of the mouse Stat3 gene is embryonic lethal at approximately E6.5-7.5 (Takeda et al 1997). Stat3 also plays an important role in mouse and rat reproduction during implantation and decidualization (Teng et al 2004a(Teng et al , 2004b. Additionally, it has recently been reported that leptin regulates porcine ovarian granulosa cell function via the JAK/STAT pathway (Ruiz-Cortes 2003).…”

Egr1 Protein Acts Downstream of Estrogen-Leukemia Inhibitory Factor (LIF)-STAT3 Pathway and Plays a Role during Implantation through Targeting Wnt4

“…Previous studies showed STAT3 is specifically activated during mouse and rat embryo implantation (10,42) and in human endometrial stromal cells during decidualization (43). Recent studies characterized STAT3 as a regulator of differentiation in human stromal cell decidualization (44).…”

Overexpression of signal transducers and activators of transcription in embryos derived from vitrified oocytes negatively affect E-cadherin expression and embryo development

“…In the other hands 398 in our study condition the lower cleavage rate, as a consequence of 399 oocyte cryopreservation, might be associated with a cytoplasmic 400 incompetence, including lack of oogenetically derived molecules 401 necessary for initiating embryogenesis [14,28,50]. 402 As shown ( implantation and decidualization [45,46]. (Table 2).…”

“…Moreover, in contrast to CDH1 the relative expression of STAT3 in vitri-43 fied derived embryos was higher than embryos derived from fresh oocytes. The overexpression of STAT3 44 in embryos derived from vitrified oocytes might be the reason for the lower CDH1 expression and in turn 45 the lower developmental competence of the resulting embryos.…”