Gene expression profiles of Chinese medaka (Oryzias sinensis) primary hepatocytes in response to estrone (E1), 17β-estradiol (E2) and estriol (E3)

The natural estrogens, including estrone (E₁), 17β-estradiol (E₂), and estriol (E₃), are frequently detected in aquatic environment at relatively high levels. The most commonly used biomarkers for estrogens are mainly expressed in the liver of fish. Analyses of the global gene profiling in fish liver cells under estrogens treatment will provide precise toxicogenomic information of the natural estrogens which is still not well known. In this study, we developed methods for isolation and culture of primary hepatocytes from liver tissue of male Chinese medaka (Oryzias sinensis), and analyzed the global gene expression profiling in the primary hepatocytes treated with E₁ (1, 10, and 100 nmol/L), E₂ (0.01, 0.1, 1, 10, and 100 nmol/L), and E₃ (1, 10, and 100 nmol/L) using RNA-seq. It was found that 175, 248, and 218 genes were differentially expressed in the E₁, E₂, and E₃ groups, respectively. These differentially expressed genes (DEGs) were mainly enriched in Gene Ontology (GO) terms of “response to estradiol”, “response to estrogen”, and “lipid transport”. Of the DEGs, vitellogenin genes, including vtg1, vtg2, and vtg3, were the mostly up-regulated and followed by zona pellucida genes which include zp2.3, zp2l1 and zp3a.2. In addition, genes of slc41a1, zp2.1, esr1, pkd1l1, fam20ca, best3, etc. were also obviously up-regulated by the estrogens in concentration-dependent patterns. RT-qPCR was used to validate the results of RNA-seq and found that vtg2 should be the best biomarker gene for estrogen study, which could well response to natural estrogens and weak estrogenic chemical, propyl 4-hydroxybenzoate.