Page 22 - HKSEMR2020 Programme book

Poster Presentation (Basic Science) Abstracts

Role of endometrial estrogen and progesterone receptors on

protein disulphide isomerase 1 (PDIA1) expression on regulating
endometrial receptivity

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Sudini R Fernando , Kiu-Wai Cheng , Benancy PC Wong , Yin-Lau Lee , Ernest HY Ng ,
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William SB Yeung , Kai-Fai Lee
1. Department of Obstetrics and Gynaecology, Li Ka Shing Faculty of Medicine, The University of Hong Kong,
Hong Kong SAR, China; 2. Department of Animal Science, Faculty of Animal Science & Export Agriculture, Uva
Wellassa University, Badulla, 50000, Sri Lanka; 3. Shenzhen Key Laboratory of Fertility Regulation, The University
of Hong Kong-Shenzhen Hospital, Haiyuan 1st Road, Futian District, Shenzhen, 518053, China
Introduction / Background / Objectives: cells collected at the receptive phase of the cycle. PDIA1 over-
expression plasmid was transfected into the receptive Ishikawa
Human endometrium is receptive to embryo implantation at a
particular time during the menstrual cycle. Differential expression cells. The spheroid attachment rate of the treated cells was
of receptive proteins on the endometrial surface is a prerequisite determined. Furthermore, endometrial tissues were collected from
for successful embryo attachment. Protein disulphide isomerase the proliferative (n = 12), secretary (n = 24), and pre-receptive (n
(PDI) family contains 21 member proteins that function as = 17) and receptive (n = 16) phases of the menstrual cycle, and
chaperones with redox activity. Our preliminary study indicated PDIA1 expression was determined by immunohistochemistry.
that PDIA1 is hormonally regulated, and a lower membrane
protein expression level was found in receptive endometrial cell Results / Outcomes:
lines. Therefore, we hypothesized that steroid hormones regulate
endometrial receptivity via modulating surface PDIA1 expression. Expression of total PDIA1 protein was high in the 4 endometrial
Furthermore, surface expression of PDIA1 generated an oxidized epithelial cell lines tested; a higher membrane PDIA1 expression
microenvironment not conducive for embryo implantation. was found in non-receptive AN3CA cells. Ishikawa and RL95-2 cells
expressed estrogen receptor alpha (ESR1), estrogen receptor beta
(ESR2) and progesterone receptors (PGR). Moreover, ESR1, ESR2
Methods: and PGR showed a cyclic expression pattern during the human
menstrual cycle. Estrogen at 0.1 to 100 nM up-regulated, while
We used receptive (Ishikawa & RL95-2) and non-receptive
(AN3CA & HEC1B) human endometrial epithelial cells for PDIA1 progesterone at 0.1 to 1 µM down-regulated PDIA1 expression.
expression analysis. The expression levels of total and membrane Mid-luteal estrogen and progesterone level down-regulated
PDIA1 proteins were determined and correlated with spheroid membrane PDIA1 but upregulated cytosolic PDIA1 expression in
attachment rate onto endometrial cells. The effects of estrogen, Ishikawa cells. PDIA1 expression is high in luminal epithelium at
progesterone and the inhibitors of their receptors on PDIA1 the proliferative phase of human endometrium compared to the
expression in Ishikawa cells were studied. The expressions secretary phase, and there was no change in the expression of
levels of total and membrane PDIA1 protein in the Ishikawa cells PDIA1 in glandular epithelium between the two phases. PDIA1
were determined after a 24-hr treatment of estrogen (0.01-100 expression in luminal epithelium at the pre-receptive phase
nM) and/or progesterone (0.01-1 µM) by western blotting and was higher than the receptive phase. ESR1 antagonist MPP, but
immunohistochemistry. PDIA1 small interfering RNA (siRNA) and not ESR2 antagonist PHTPP, blocked the stimulatory effect of
inhibitor bacitracin, disulphide reducing agent TCEP and oxidizing estrogen (10 nM) on PDIA1 expression in Ishikawa cells. Similarly,
agent diamide were used to treat the non-receptive (AN3CA), knockdown of ESR1 by siRNA suppressed the stimulatory effect of
receptive (Ishikawa) or human primary endometrial epithelial estrogen (10 nM) on PDIA1 expression. Addition of PGR antagonist
mifepristone nullified the suppressive effect of progesterone (0.1
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