Study On The Molecular Mechanism Of The Expression Of Vtg Gene Exposed By BPA And EE2 In Rare Minnow Gobiocypris Rarus

Endocrine-disrupting chemicals(EDCs) are presented in the environment and interfere in some waywith normal endocrine function of wild animal and human.Bisphenol A(BPA) and 17α-ethinylestradiol(EE2) are two EDCs whichwidely used in the production and life and they will eventually inflow into the water, damaged the reproductive and endocrine system of aquatic animals.Vitellogenins(VTG), as the precursors of major components of female yolk proteins in oviparous animals, transports a variety of nutrients for the egg cells. It has been widely reported that VTG is a biomarker to test environmental pollution. To explore the mechanismunderlying VTG synthesis influenced by BPA and EE2, we exposed the adult G. rarus to 15、225 μg/L BPAand 25 ng/L EE2 for 21 days. 1)The 5′ flanking regions ofvtgwas cloned by Genome Walker. 2) The m RNA expression of vtg, erα, erβ1, erβ2and hsp90 in livers were detectedby RT-PCR. 3) The protein expression of HSP90 and ER were detected by Western Blot.4) The protein level of HSP90-ER cmplex was detected by Co-immunoprecipitation. The main results of the present study are as follows.(1). The results showed that the estrogen responsive element(ERE) in the 5′ flankingregionsof G. Rarusvtg supported that ER can involve in vtg m RNA expression.(2). 15 and 225 μg/L BPA induced a dose-dependentstimulative effecton hepatic vtg transcription. EE2 caused the most significant increase on the expression of vtg.The expression oferα was alsosignificant induced in both three exposure groups. And erαis significantlyrelated tovtg.It suggested that the expression of vtg has strong correlation with erα.(3). The m RNA expression of hsp90 was significant induced in livers of male G. rarus. But in females, the expression of HSP90 exhibited an increase but not significant increase on both transcription and translation level after BPA(15 μg/L) and EE2(25ng/L) exposure. The expression of ER protein showed an increase but not significant trend in both three exposure groups, similarly to the expression of m RNA.(4). Under15 and 225 μg/L BPA exposure, the combination of ER and HSP90 decreased,with a dose-dependent manner. EE2 induced the most obvious inhibition on the combination of HSP90-ER complex.The results suggest that BPA and EE2 can facilitate the dissociation of HSP90-ER and the free ER participate in the expression of vtg.In summary, the study explored the mechanism underlying VTG synthesisafter exposed by BPA and EE2 in livers of G.rarus.These findings provide a reliable theoretical basis and foundation inthe subsequent research workof BPA and EE2.