Attenuated Expression Of MTR In The Hyperandrogenic Phenotype Of PCOS

ObjectivePolycystic ovary syndrome(PCOS)is a common endocrine,metabolic and heterogeneous disorder in women of reproductive age,the exact etiology of which remains unknown.Using microarray analysis,differentially expressed genes were identified and validated in ovaries from prenatally androgenized(PNA)mice,to unravel the molecular mechanisms underlying the hyperandrogenic phenotype of PCOS.MethodsAdult ICR female mice were mated at 8wks of age.Pregnant dams received daily subcutaneous injection of 70 ?l of sesame oil containing 350 ?g of dihydrotestosterone(DHT)or sesame oil vehicle on gestation days 16-18 to generate PNA offspring.PCOS phenotypes in the PNA offspring were validated through assessing estrous cyclicity,testosterone levels,ovarian histology and follicle counting.Gene expression in the offspring ovary was examined by microarray.Differentially expressed genes were validated by q RT-PCR,immunohistochemistry(IHC)and western blot.Women with the hyperandrogenic phenotype of PCOS and age-matched controls were recruited from the Center for Reproductive Medicine of Nanjing Drum Tower Hospital.The diagnosis of PCOS was based upon the 2003 Rotterdam Diagnostic Criteria.All patients with PCOS in this study had oligomenorrhea,hyperandrogenism,and a clear diagnosis of polycystic ovaries by ultrasonography.The granulosa cells around oocytes were collected for q RT-PCR.ResultsHyperandrogenism disrupted estrous cyclicity,impaired fertility,increased serum testosterone levels while altering ovarian morphology and folliculogenesis in PNA mice.Using microarray analysis,1188 differentially expressed genes,including 671 upregulated and 517 downregulated genes,were identified in ovaries of PNA mice.Five differentially expressed genes(Aldh1a7,Bhmt,Mtr,Nrcam,Ptprg)were validated by q RT-PCR.Ovarian MTR downregulation in PNA mice was further validated by IHC and western blot.Likewise,women with hyperandrogenic phenotype of PCOS had decreased MTR m RNA levels in their granulosa cells compared with healthy controls.In addition,serum levels of S-adenosyl methionine(SAM),the downstream product of MTR,were decreased in PNA mice and women with the hyperandrogenic phenotype of PCOS.Conclusions1)Our study shows that prenatal androgenization of the ICR mouse with DHT is anideal model for emulating the hyperandrogenic phenotype of PCOS in women,with the PNA mice having polycystic ovaries.2)We identified multiple novel candidate genes,including MTR,that might play a role in the hyperandrogenic phenotype of PCOS.3)Our evidence for the first time shows that an abnormal one-carbon metabolism pathway is linked to the hyperandrogenic phenotype of PCOS.