Expression Analysis of Estrogen-responsive Genes Vitellogenin 1 and 2 in Liver of Male Medaka (Oryzias latipes) Exposed to Selective Ligands of Estrogen Receptor Subtypes

Abstract

Vitellogenin (VTG) is a useful biomarker for detecting the estrogenic activity of chemicals in aquatic environments. However, little information is available on the regulatory mechanisms of the expression of each VTG subtype, particularly the relationship between expression patterns of VTG1/2 and estrogen receptor (ER) subtypes, such as ERα and ERβ. In this paper, we measured VTG1 and VTG2 mRNA induction in male medaka liver, which was treated with ERα-selective ligand, (17α, 20E)-3-hydroxy-17,20-[(1-methoxyethylidene)bis(oxy)]-19-norpregna-1,3,5(10),20-tetraene-21-carboxylic acid, methyl ester or ERβ-selective ligand, 2-(4-hydroxyphenyl)-5-hydroxy-1,3-benzoxazole and investigated the characteristics of ER subtype function in VTG1 and VTG2 inductions. Hepatic VTG1 mRNA was induced by ERα-selective ligands at even low concentration and maximum increases were the same as for E2. VTG2 mRNA was also increased, but its levels were very low. On the other hand, ERβ-selective ligands significantly increased VTG2 mRNA in the presence of ERα agonists. These results indicate that the expression of each VTG subtype is regulated by unique ER subtypes. VTG1 expression is only regulated by the action of ERα. In contrast, VTG2 expression is regulated by both ERα and ERβ, with ERα being essential for VTG2 gene expression and ERβ being essential for enhancement.

In vivo and in silico analyses of estrogenic potential of bisphenol analogs in medaka (Oryzias latipes) and common carp (Cyprinus carpio)

“…The male medaka fish (approximately 4 months after hatching) were exposed to the test compounds according to a method reported previously (Yamaguchi et al, 2005(Yamaguchi et al, , 2009). The BP exposure concentrations were selected based on the results of a previous study (Kitamura et al, 2005;Delfosse et al, 2012).…”

“…Total RNA was prepared and reverse transcription was performed as described previously (Yamaguchi et al, 2005(Yamaguchi et al, , 2009. Liver mRNA was quantified by the real-time polymerase chain reaction (PCR) using the FullVelocity SYBR Green Master Mix (Stratagene, La Jolla, CA, USA) and Stratagene Mx3000P TM (Stratagene) (Yamaguchi et al, 2005(Yamaguchi et al, , 2009).…”

“…Liver mRNA was quantified by the real-time polymerase chain reaction (PCR) using the FullVelocity SYBR Green Master Mix (Stratagene, La Jolla, CA, USA) and Stratagene Mx3000P TM (Stratagene) (Yamaguchi et al, 2005(Yamaguchi et al, , 2009). The specific primers for the estrogen-responsive and reference genes are provided in Supplementary material, Table S1.…”

Sharing the Roles: An Assessment of Japanese Medaka Estrogen Receptors in Vitellogenin Induction

“…This corroborates previous studies illustrating that both ERα and ERβs are necessary for vitellogenesis in medaka, zebrafish and goldfish. 52–54 Yamaguchi and colleagues also illustrate that all three mER subtypes are capable of regulating mVTG and mCHG expression, in a study which used mERα- and mERβ-selective agonists (orthoester-2k and 2-(4-hydroxyphenyl)-5-hydroxy-1,3-benzoxazole [HPHB], respectively). 54,55 …”

Hexestrol- and nonylphenol-induced differential vitellogenin synthesis in female and male barfin plaice Liopsetta pinnifasciata

“…Among marine species it is barfin flounder Verasper moseri (Matsubara and Koya, 1997), haddock Melanogrammus aeglefinus (Reith et al, 2001) and red seabream Pagrus major (Sawaguchi et al, 2006). Data are very limited concerning the differential regulation of the various Vtg types (Yamaguchi et al, 2009), succession and proportion of Vtgs synthesised in female fish at different stages of the reproductive cycle Sawaguchi et al, 2008). Recently, different expression of vitellogenin genes VgA and VgB in response to single dose of E2 was found in freshwater murrel Channa punctatus:…”