P-515 EHD1 impaired endometrial decidualization linked to recurrent implantation failure through SENP1-mediated progesterone resistance
Authors: 张 慧 , Jiang Y , Yan G , Sun H 
Published: June 2023

Abstract

Study question
Recurrent implantation failure (RIF) patients exhibit poor endometrial receptivity and abnormal decidualization with reduced effectiveness to progesterone, an intractable clinical problem with elusive mechanisms.

Summary answer
EHD1 overexpression promoted the SUMOylation and ubiquitinated degradation of the PRB protein leading to decreased transcriptional activity and responsiveness of endometrial stromal cells to progesterone.

What is known already
Abnormal decidualization is a significant cause of infertility in RIF patients. A previous study has demonstrated that EH homeodomain 1 (EHD1) is significantly elevated in the endometrium of RIF patients and plays an essential role in the decidualization of human endometrial stromal cells (HESCs). However, far less is known about the function of EHD1 in the endometrium during embryo implantation.

Study design, size, duration
After approval from the Ethics Committee of Nanjing Drum Tower Hospital (2013-081-01), endometrial specimens were collected from women who received treatment at the Reproductive Center of Nanjing Drum Tower Hospital from January 2020 to December 2021. Twelve RIF women and Twelve fertile normal control women were enrolled in the present study. Endometrium in the middle and late stages of secretion was obtained by aspiration and curettage 5-7 days after ovulation.

Participants/materials, setting, methods
The expression and location of EH homeodomain 1 (EHD1) in endometrium were evaluated by IHC, qRT-PCR and Western blotting. Transcriptomic analysis was performed to predict the mechanism by which EHD1 is mediated in human endometrial stromal cells (HESCs) decidualization. Luciferase reporter assays and Western blotting were used to detect the protein activity and stability of progesterone receptor B (PRB) regulated by EHD1. The potential mechanisms were further confirmed through immunoprecipitation, nucleocytoplasmic separation and immunofluorescence experiments.

Main results and the role of chance
EHD1 was abnormally elevated in RIF patients and linked to aberrant endometrial decidualization. EHD1 overexpression inhibited progesterone receptor (PGR) transcriptional activity and the responsiveness of HESCs to progesterone. Indeed, EHD1 overexpression promoted the SUMOylation of PRB, leading to ubiquitinated degradation of the PRB protein. Supplementation with the de-SUMOylated protease SENP1 ameliorated EHD1-repressed PRB transcriptional activity. In addition, the expression of PRL and IGFBP1 was rescued by interfering with the expression of EHD1 in HESCs from RIF patients.

Limitations, reasons for caution
In our study, we provided novel insight into the molecular scaffold of EHD1 to mediate the ubiquitination of PRB for degradation. However, our data do not account for the specific mechanisms by which EHD1 promotes the ubiquitination of PRB, and The specific enzymes involved remain to be elucidated.

Wider implications of the findings
We demonstrated that abnormally high expression of EHD1 in endometrial stromal cells attenuated the activity of PRB associated with progesterone resistance in a subset of women with RIF.

Trial registration number
not applicable