ARID1A and PGR proteins interact in the endometrium and reveal a positive correlation in endometriosis

Abstract

Endometriosis is a disorder in which endometrial cells normally limited to the lining of the uterus proliferate outside the uterine cavity and can cause pelvic pain and infertility. ARID1A levels are significantly reduced in the eutopic endometrium from women with endometriosis. Uterine specific Arid1a knock-out mice were infertile due to loss of epithelial progesterone receptor (PGR) signaling. However, the functional association of ARID1A and PGR in endometriosis has not been studied. We examined the expression patterns and co-localization of ARID1A and PGR in eutopic endometrium from women with and without endometriosis using immunostaining and Western blot analysis. ARID1A and PGR proteins co-localized in the epithelium during the proliferative and the early secretory phases. Our immunoprecipitation analysis and proximity ligation assay (PLA) revealed physical interaction between ARID1A and PGR-A but not PGR-B in the mouse and human endometrium. ARID1A levels positively correlated with PGR levels in the eutopic endometrium of women with endometriosis. Our results bring new perspectives on the molecular mechanisms involved in endometrial receptivity and progesterone resistance in endometriosis. The interrelationship between ARID1A and PGR may contribute to explaining the non-receptive endometrium in endometriosis-related infertility.

Keywords: ARID1A; Endometriosis; Endometrium; Progesterone receptor.

Figure 1.. The co-localization of PGR and ARID1A in the human endometrium during the menstrual cycle.

(A) The expression of PGR (green) and ARID1A (red) as examined by double immunofluorescence analysis in human endometrial sections from the proliferative (a to c), early secretory (d to f), and mid secretory (g to i) phases. Nuclei were stained by DAPI (blue). (B) Quantification analysis for compartmental expression of PGR, ARID1A, and PGR/ARID1A localized cells (merge) from 13 proliferative, 13 early secretory, and 6 mid secretory. Mean ± SEM, * p<0.05, ** p<0.01, *** p<0.001.

Figure 2.

ARID1A directly interacts with PGR in the mouse and human endometrium. (A) Immunoprecipitation showed that endogenous ARID1A interacts with PGR-A in mouse (top) and human (bottom) endometrial samples. (B) Duolink In Situ PLA demonstrated that ARID1A strongly interacts with PGR-A following transient co-transfection but not individual transfection in the human endometrial cancer HEK293T cell line and (C) in vivo in human endometrial samples throughout the menstrual cycle (n=5/phase).

Figure 3.. ARID1A has positive correlation with PGR in women with endometriosis.

(A) ARID1A and PGR expression were examined by Western blot analysis in women with endometriosis during the early (n=13), mid (n=12), and late secretory (n=10) phase. (B) Correlation analysis revealed a significant positive correlation between ARID1A and PGR-A and (C) between ARID1A and PGR-B proteins in endometriosis patients.

Figure 4.. The increase of endometriotic lesions in mice due to loss of PGR and ARID1A.

(A) The induction of endometriosis in mice with loss of ARID1A and PGR enhanced the development of endometriotic lesions. (B) Quantification of endometriotic lesions 1 month after induction of endometriosis (n=5/genotype).