Co-expression of galectin-3 and v3 integrin at pinopodes of human endometrium

Pinopodes are suggested as biological markers of uterine receptivity, but their molecular components are unknown.

Co-expression of galectin-3 and v3 integrin at human pinopodes has been examined in this study to propose a role for them during adhesion phase of embryo implantation.

Biopsies were obtained from early and mid luteal phase endometrium of 12 fertile women with regular menstrual periods (25-35 days) and the mean age of 37 years (range 25–45). Then, they were examined under light and scanning electron microscopy for detection and dating of pinopodes. Using immunofluorescent staining and immunogold electron microscopy, the expression of galectin-3 and v3 integrin in human endometrium and pinopodes was detected. Further, statistical analysis was performed using immunogold electron microscopy to investigate the expression and subcellular distribution of these, before and during the frame of implantation window.

The results demonstrated that pinopodes of luminal epithelial cells exhibited immunoreactivity for both galectin-3 and v3 integrin, which was increased statistically significant (p< 0.05) at the time of implantation window. Furthermore, area-related distribution of these proteins was found higher in pinopodes compared to the neighboring apical membrane without pinopode.

Temporal and spatial expression of galectin-3 and v3 integrin at pinopodes proposes a role for pinopodes in the adhesion of embryo and the involvement of galectin-3 as a binding partner of integrins in the human utero-fetal complex.