Session: OR36-Ovarian & Uterine Function
Room 104 (Moscone Center)
To overcome difficulties associated with investigating implantation in vivo, we utilised two in vitro models: mouse embryos, and a model in which the implanting embryo is replaced by embryo-sized beads (Afﬁ-gel Blue; Bio-rad; 80–150μm). Beads preloaded with IGF-I (100ng/ml;2h) were transferred to human endometrial epithelial Ishikawa cells (as a model of the uterine luminal epithelium). Both mouse embryos and ligand-conjugated beads (but not control beads) attached to the apical surface of conﬂuent cells. To examine whether miR-145 could inﬂuence this process, Ishikawa cells were transfected with a synthetic pre-miR-145 mimetic (100 nM) or negative control pre-miR for 48 h. Attachment of IGF-bearing beads or embryos was monitored microscopically and quantified using a stability scale. Embryos or IGF-I-loaded beads reached 70% on the scale when cells had been transfected with negative control pre-miR, but following miR-145-overexpression, the stability of embryos or beads was reduced by at least 80% relative to control. To explore the mechanism further, we investigated the gene targets of miR-145. Western blot analysis revealed that miR-145 overexpression decreased IGF1R expression to 14% of control. IGF1R knockdown reduced bead attachment stability to 11% of the control level.
In summary, by utilising two novel in-vitro models of implantation, we have begun to dissect the molecular mechanisms regulating embryo-endometrial attachement. Using this model we have revealed that IGF1R is a critical component within the endometrium that is required for successful implantation. Furthermore, IGF1R expression is closely regulated by miR-145. We hypothesise that miR-145 overexpression causes infertility by blocking embryo (IGF-I)–maternal (IGF1R) interactions at implantation.
Nothing to Disclose: YJK, KF, JDA
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