Evidence For Hmgn2 Involvement in Mouse Embryo Implantation and Decidualization

Abstract

Background/Aims: Hmgn2 is involved in regulating embryonic development, but its physiological function during embryo implantation and decidualization remains unknown. Methods: In situ hybridization, real-time PCR, RNA interference, gene overexpression and MTS assay were used to examine the expression of Hmgn2 in mouse uterus during the pre-implantation period and explore its function and regulatory mechanisms in epithelial adhesion junction and stromal cell proliferation and differentiation. Results: Hmgn2 was primarily accumulated in uterine luminal epithelia on day 4 of pregnancy and subluminal stromal cells around the implanting blastocyst at implantation sites on day 5. Similar results were observed during delayed implantation and activation. Meanwhile, Hmgn2 expression was visualized in the decidua. In uterine epithelial cells, silencing of Hmgn2 by specific siRNA reduced the expression of adhesion molecules Cdh1, Cdh2 and Ctnnb1 and enhanced the expression of Muc1, whereas constitutive activation of Hmgn2 exhibited the opposite effects, suggesting a role for Hmgn2 in attachment reaction during embryo implantation. Estrogen stimulated the expression of Hmgn2 in uterine epithelia, but the stimulation was abrogated by ER antagonist ICI 182,780. Further analysis evidenced that attenuation of Hmgn2 might eliminate the regulation of estrogen on the expression of Cdh1, Cdh2 and Ctnnb1. In uterine stromal cells, progesterone induced the accumulation of Hmgn2 which advanced the expression of Prl8a2 and Prl3c1, two well-known differentiation markers for decidualization, but did not affect the proliferation of stromal cells. Knockdown of Hmgn2 blocked the progesterone-induced differentiation of uterine stromal cells. Moreover, Hmgn2 might serve as an intermediate to mediate the regulation of progesterone on Hand2. Conclusion: Hmgn2 may play an important role during embryo implantation and decidualization.

High Mobility Group Box 1 Regulates Uterine Decidualization through Bone Morphogenetic Protein 2 and Plays a Role in Kruppel-Like Factor 5-Induced Stromal Differentiation

“…Indeed, knockdown of Hmgb1 in MGC-803 gastric cancer cells and embryonic stem cells resulted in an accumulation of cells in the G0/G1 phase along with the simultaneous reduction in the proportion of cells in the S phase, whereas administration of recombinant Hmgb1 protein to mesangial cells exhibited the opposite effects [25][26][27]. Simultaneously, Hmgb1 also promoted the expression of Prl8a2 which was a reliable differentiation marker for decidualization [16,17], indicating a role of Hmgb1 in stromal differentiation. The notion was reinforced by the finding that silencing of Hmgb1 could impede the induction of Prl8a2 elicited by cAMP which facilitated the differentiation of uterine stromal cells accompanying with the elevated expression of Hmgb1.…”

“…To explore the role of Hmgb1 in stromal cell differentiation, we analyzed its effects on the expression of prolactin family 8, subfamily a, member 2 (Prl8a2) which is a reliable differentiation marker for decidualization [16,17]. The results evidenced that after Hmgb1 siRNA treatment, the level of Prl8a2 mRNA exhibited an obvious reduction (Fig.…”

“…Uterine stromal cells were isolated as previously described [16,17]. Briefly, uterine horns from day 4 pregnant mice were split longitudinally and digested in HBSS containing 1% trypsin and 6 mg/ml dispase (Roche).…”

Decidual expression and regulation of Fatty acid desaturase 3 during mouse decidualization

“…After stromal cells were induced for in vitro decidualization, there was a significant induction of Dtprp, Prl3c1 and Bmp8a (Fig. 5), reliable markers for mouse in vitro decidualization (Kimura et al 2001, Bany & Cross 2006, Kelleher et al 2017, Li et al 2017. Meanwhile, Fads3 expression was also significantly induced under in vitro decidualization for 12, 24, 48 and 72 h, respectively (Fig.…”

Assessment of Embryo-Induced Transcriptomic Changes in Hamster Uterus Using RNA-Seq

“…The mouse is widely used as an animal model for studying human embryo implantation [7-10]. The mouse as well as the rat is unique in that both maternal progesterone and estrogen are critical to implantation, whereas in the majority of species including humans, implantation can occur in the presence of progesterone alone and ovarian estrogen is not needed [11].…”