PCAF impairs endometrial receptivity and embryo implantation by down-regulating β3-integrin expression via HOXA10...

Homeobox A10 (HOXA10), a key transcription factor, plays a critical role in endometrial receptivity by regulating the expression of downstream target genes, such as β3-integrin (ITGB3), but little is understood about the mechanisms of the posttranslational modification of HOXA10 during embryo implantation.

The aim of this study was to assess the effect of HOXA10 acetylation by p300/CREB-binding protein-associated factor (PCAF) in the embryo implantation process.

The association of HOXA10 with PCAF was detected by coimmunoprecipitation, Western blotting, and confocal immunofluorescent assays. A luciferase reporter assay, Western blotting, quantitative real-time PCR, and chromatin immunoprecipitation techniques were used to determine the effect of PCAF on HOXA10 protein stability and the HOXA10-mediated regulation of ITGB3 expression. HOXA10-PCAF association on embryo implantation was evaluated using a BeWo spheroid attachment assay. PCAF expression in the eutopic endometrium of women with endometriosis and fertile controls was measured by Western blotting technique.

PCAF was identified as an HOXA10-interacting protein and inhibited HOXA10-mediated ITGB3 transcription via acetylating HOXA10 at K338 and K339. Overexpressing or knocking down PCAF in Ishikawa cells showed that PCAF not only down-regulated HOXA10-mediated ITGB3 protein expression but also diminished HOXA10-mediated embryo adhesiveness by acetylating HOXA10 (P < .05). Furthermore, we found aberrantly high PCAF expression in the eutopic endometrium of women with a diagnosis of endometriosis compared with the fertile controls (P < .05).

These observations demonstrate that 1) HOXA10 associates with and is acetylated by PCAF at lysines K338 and K339 in Ishikawa cells and 2) HOXA10-PCAF association impairs embryo implantation by inhibiting ITGB3 protein expression in endometrial epithelial cells.