Differential regulation of two genes implicated in fish reproduction: Vitellogenin and estrogen receptor genes

Abstract

In rainbow trout as well as in other species, variability of estrogen receptor (ER) gene expression according to the cell type and the physiological state reflects a differential cell and gene sensitivity to estrogen. We previously demonstrated that expression of the rainbow trout estrogen receptor (rtER) and vitellogenin (Vg) genes were induced differently by estrogens in rainbow trout liver. Therefore, these two genes offered a suitable model to study the influence of ER concentration on gene transcriptional activities. In the present study we show that the transcription rate of rtER and Vg genes during an estrogenic treatment are affected differently by variation of cellular ER concentration. We demonstrate that rtER gene exhibits a low threshold response to loaded estrogen receptor, and increasing ER amounts do not affect the transcriptional response of this gene during an estrogenic stimulation. On the contrary, Vg gene expression requires the presence of a higher loaded estrogen receptor level to be induced, and its transcriptional response is directly proportional to the amount of synthesised ER. Mol. Reprod. Dev. 48:317–323, 1997. © 1997 Wiley‐Liss, Inc.

Long-term exposure investigating the estrogenic potency of estriol in Japanese medaka (Oryzias latipes)

“…Numerous experimental studies have reported that liver Vtg and ER mRNA levels increased simultaneously after the treatment of fish with (xeno)-estrogens (Atteke et al, 2003;Andreassen et al, 2005;Zhang and Hu, 2008;Adedeji et al, 2012). Flouriot et al (1997) considered that the upregulation of Vtg mRNA depends directly on the number of estrogen receptors (ER), which are also regulated at the mRNA level by estrogen treatment in fish. However, in this study, we noted significant increases in the hepatic Vtg gene levels and no decrease statistically in ERα gene levels in fish treated with E3.…”

Effects of estrone on the early life stages and expression of vitellogenin and estrogen receptor genes of Japanese medaka (Oryzias latipes)

“…Other studies reported that liver vitellogenin and ERa mRNA levels increased simultaneously after estrogen compound treatment in fish (Atteke et al, 2003;Andreassen et al, 2005). Flouriot et al (1997) also considered that the up-regulation of Vtg mRNA depends directly on the number of estrogen receptors, which are also regulated at the mRNA level by estrogen treatment in fish. However, in this study, we noted profound decreases in the hepatic Vtg mRNA in female medaka treated with E1.…”

Expression Profiling of Estrogenic Compounds Using a Sheepshead Minnow cDNA Macroarray

“…Several genes known to be activated by this process include those that encode the ER itself, vitellogenins (Vtgs), and choriogenins (Arukwe et al 2001;Bowman et al 2000;Celius et al 2000;Denslow et al 2001aDenslow et al , 2001bFlouriot et al 1995Flouriot et al , 1996Flouriot et al , 1997Folmar et al 2000;Funkenstein et al 2000;Hemmer et al 2001;Lattier et al 2001;Le Guellec et al 1988;Lim et al 1991;Murata et al 1997). Vtgs, the egg yolk precursor proteins, and choriogenins, which are required for making the inner covering of the egg, normally increase in the circulation of females during oogenesis (Mommsen and Walsh 1988;OppenBerntsen et al 1992;Specker and Sullivan 1994;Tyler and Sumpter 1996).…”