Altered aquaporin expression in women with polycystic ovary syndrome: hyperandrogenism in follicular fluid inhibits aquaporin-9 in granulosa cells through the phosphatidylinositol 3-kinase pathway.
BACKGROUND
The present study was designed to evaluate whether the alteration of aquaporin-9 (AQP-9) expression in granulosa cells (GCs) of patients with polycystic ovary syndrome (PCOS) was associated with the hyperandrogenism in follicular fluid (FF).


METHODS
We recruited infertile women with PCOS (n = 14) and infertile women with tubal blockage (controls, n = 31) for this study. We examined total testosterone (TT), free androgen index (FAI), sex hormone-binding globulin (SHBG), FSH, LH and estradiol in FF. Real-time PCR and western blotting were performed to assess AQP-9 expression in GCs, including effects of dihydrotestosterone (DHT) in vitro.


RESULTS
AQP-9 protein was localized in the nucleus, cytoplasm and cell membrane of the human GCs. The TT, FAI and LH levels were all higher, and SHBG levels lower, in the FF of women with PCOS versus controls (P = 0.0145, 0.0001, 0.0191, 0.0001, respectively). AQP-9 mRNA level in GCs of patients with PCOS was tightly correlated with the TT, SHBG levels and FAI in FF (P = 0.0020, 0.0001, 0.0020, respectively). In vitro, DHT (10(-9) mol/l) decreased AQP-9 mRNA (lowest at 12 h) and protein levels in control GCs (P = 0.0005, 0.0247, respectively). The inhibitory effect of DHT on AQP-9 mRNA was attenuated by LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor (P = 0.0013). Fifty micromolar 4-(hydroxymercuri) benzoic acid sodium salt (PMB) and 10(-9) mol/l DHT blunted the swelling of GCs in hypotonic medium, respectively (P = 0.0350, 0.0027).


CONCLUSIONS
Hyperandrogenism in FF of women with PCOS inhibited AQP-9 in GCs through the PI3K pathway.
Qu
Fan
F
Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, 2 Xueshi Road, Hangzhou, Zhejiang Province 310006, China.
Wang
Fang-Fang
FF
Lu
Xiu-E
XE
Dong
Min-Yue
MY
Sheng
Jian-Zhong
JZ
Lv
Ping-Ping
PP
Ding
Guo-Lian
GL
Shi
Bi-Wei
BW
Zhang
Dan
D
Huang
He-Feng
HF
D000328:Adult; D000704:Analysis of Variance; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D013196:Dihydrotestosterone / Q000008:administration & dosage / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005455:Fluorescent Antibody Technique; D015571:Follicular Fluid / Q000737:chemistry; D006107:Granulosa Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D017588:Hyperandrogenism / Q000235:genetics / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000032:analysis; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011085:Polycystic Ovary Syndrome / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D015398:Signal Transduction / Q000502:physiology; D013739:Testosterone / Q000032:analysis
C109669:AQP9 protein, human; D020346:Aquaporins; D012738:Sex Hormone-Binding Globulin; D013196:Dihydrotestosterone; D013739:Testosterone; D007986:Luteinizing Hormone; D019869:Phosphatidylinositol 3-Kinases