Poster Presentation ESA-SRB-ANZBMS 2024 in conjunction with ENSA

Endocytosis in Uterine Epithelial Cells – Investigating the localisation and abundance of ITSN2 during early pregnancy in rats and humans. (#484)

Sofija Filipovic 1 , Samson Dowland 1 , Laura Lindsay 1
  1. School of Medical Science, University of Sydney, Sydney, NSW, Australia

The successful implantation of a blastocyst is dependent on changing epithelial cell morphology during what is known as the “receptive period” in the uterus. These morphological changes are communicated in part, by blastocyst derived factors in uterine luminal fluid, however there is limited understanding of the mechanisms that allow for these signals to be received by the maternal endometrium. Clathrin mediated endocytosis is the predominant internalisation pathway in mammalian cells, requiring the recruitment of “clathrin coated vesicles” to envelop and transport cargo across the membrane. Endocytosis has previously been shown to occur in uterine epithelial cells, however the exact mechanisms surrounding the involvement of clathrin mediated endocytosis in uterine receptivity are not comprehensively understood. Using immunofluorescence microscopy and western blotting, this study aimed to investigate the localisation and abundance of intersectin-2 (ITSN2), a protein involved in clathrin mediated endocytosis, in uterine epithelial cells during early pregnancy in rat tissue and cultured human endometrial cells (HEC-1A and RL95-2). Immunofluorescence imaging of rat uterine tissue revealed a sustained apical localisation of ITSN2 throughout early pregnancy, and western blotting revealed heightened abundance in non-receptive tissue. This suggests a role for clathrin mediated endocytosis in the implantation process, likely in receiving vesicular blastocyst-derived cargo and signalling which induces morphological changes and initiates receptivity. Apical presence of the protein in pre-receptive (day 1) tissue could also indicate an immunological role, facilitating interaction of the endometrium with paternal antigens in seminal fluid at the time of fertilisation. This data provides important context for understanding the role of clathrin mediated endocytosis in uterine epithelial cells.