Stomatin-like protein 2 is involved in endometrial stromal cell proliferation and differentiation during decidualization in mice and humans.

The molecular mechanisms underlying endometrial stromal cell proliferation and differentiation (decidualization) are still not fully understood. This study revealed that increased Slp-2 expression is a significant factor modulating endometrial stromal cell proliferation and decidualization in both mice and humans. Our results showed a significant difference in the mRNA and protein levels between the implantation site and inter-implantation site on day 5 and day 6 of pregnancy in mice (all P < 0.05). Strong Slp-2 immunostaining was mainly localized within the decidual zone of mice through the post-implantation period. Mice with artificially induced deciduoma showed significantly higher expression of Slp-2 compared with uninduced controls (P < 0.005). Human stromal cells in the middle and late-secretory phases demonstrated significantly (all P < 0.05) upregulated SLP-2, compared with cells in the proliferative phase and early secretory phases. Further analyses of the SLP-2 gene knocked down revealed a significant (P < 0.005) repression of both the decidualization marker gene's expression (decidual/trophoblast prolactin-related protein in mice, insulin-like growth factor binding protein and prolactin in human) and the cell proliferation in in vitro-induced decidualized primary endometrial stromal cells in mice and humans.