305. OPPOSING ROLES FOR MUCINS 13 AND 15 IN EARLY PREGNANCY
C. E. Poon A , M. Day B and C. R. Murphy AA Discipline of Anatomy & Histology, The University of Sydney, Sydney, NSW, Australia.
B Discipline of Physiology, The University of Sydney, Sydney, NSW, Australia.
Reproduction, Fertility and Development 22(9) 105-105 https://doi.org/10.1071/SRB10Abs305
Published: 6 September 2010
Abstract
Successful pregnancy is dependent on the cumulation of numerous changes in both the uterine luminal epithelium (ULE) and the invading blastocyst prior to implantation. The apical surface of the ULE constitutes the first point of contact with the blastocyst; thus forming an important player in the implantation event. A constituent of this surface comprises the Mucin family of proteins, which is suggested to play an important role in implantation. Prior studies have found that some Mucins form an anti-adhesive surface on the uterine epithelium to prevent implantation of the blastocyst. The formation of this anti-adhesive surface relates to their large extracellular domains which act to ‘mask’ adhesive receptors present on the ULE from interaction with corresponding ligands present on the blastocyst surface. This process of contact inhibition has been termed ‘steric hindrance’. This study examined the localisation of previously uncharacterised Mucins 13 and 15 in the uterus and blastocyst during early pregnancy to investigate their role in the implantation event. Western blotting, cell fractionation and immunofluorescence techniques were utilised in this study. It was found that Mucin 13 localised to the apical cell surface of the ULE at time of implantation while conversely Mucin 15 was lost from the apical cell surface. In the blastocyst, both proteins were localised to the trophoblast cells and the inner cell mass, with Mucin 15 additionally present in the zona pellucida. Further, the changes in localisation of these proteins in the ULE corresponded to changes in their glycosylation profiles from pre-implantation to time of implantation. These results demonstrate that Mucins 13 and 15 participate in contrasting roles in implantation. Mucin 13 may promote adhesion between the uterus and blastocyst to facilitate implantation while Mucin 15 may prevent adhesion through the mechanism of steric hindrance, given its absence from the apical cell surface at time of implantation.
