Appearance of Vitellogenin mRNA Sequences and Rate of Vitellogenin Synthesis in Chicken Liver following Primary and Secondary Stimulation by 17beta-Estradiol

Abstract

Vitellogenin mRNA present in total liver RNA was determined by hybridization with labeled DNA complementary to vitellogenin mRNA. In the liver of control chicks less than 0.0001% of total cellular RNA hybridized with the vitellogenin cDNA probe. About 6 h after a first estradiol injection (primary stimulation) a significant increase in vitellogenin mRNA was observed. The initial rate of accumulation of mRNA was approximately two molecules per minute per gene, 48 h later we measured a total of 7000 mRNA molecules per diploid genome (or 0.075% of total RNA). Secondary stimulation was initiated 3 weeks later when the concentration of vitellogenin mRNA had returned to the baseline of controls. Upon the second injection of estradiol (secondary stimulation) an immediate increase in the number of vitellogenin mRNA sequences was observed. The initial rate of accumulation of mRNA was approximately six molecules per minute per gene, reaching 48 h later a total of 14000 mRNA molecules per diploid genome (or 0.128% of total cellular RNA). The relative rate of vitellogenin synthesis in vivo was studied by pulse labeling and radioimmunochemical techniques. During the primary stimulation the rate of vitellogenin synthesis in vivo parallels the increase in vitellogenin mRNA concentration and 48 h later vitellogenin represented about 9% of the newly synthesized liver proteins. During the secondary stimulation the rate of vitellogenin synthesis increased first slowly during the first 6 h and then it ran parallel to the accumulation of vitellogenin mRNA. Two days later vitellogenin represented about 16% of the pulselabeled liver proteins.

Isolation of chicken vitellogenin I and III cDNAs and the developmental regulation of five estrogen-responsive genes in the embryonic liver.

“…This estimate for the abundance of VTGII RNA falls between the two determinations reported previously (Gruber et al 1976;Jost et al 1978). Our results indicate that VTGI RNA is expressed at 11,000 molecules per cell and VTGIII RNA at 3,000 molecules per cell.…”

“…Interestingly, whereas the primary and secondary lags observed prior to the rapid accumulation of VTGIII RNA (Fig. 5B) are very similar to those described previously for VTGII (Jost et al 1978;, the lag times for VTGI (Fig. 5A) are significantly longer.…”

“…Based on our analysis of the kinetics of the accumulation of RNA of the five major yolk protein genes, it is striking that the order in which the yolk protein genes are activated following a single injection estradiol (Fig. 5;Jost et al 1978;Wiskocil et al 1980;) is similar to the order in which the respective genes can be expressed in response to estradiol during development ( Fig. 6; .…”

“…These relative values are similar to the ratio of the VTG proteins synthesized in adult estrogenized roosters (Wang et al 1983), indicating that there is no appreciable differential translational control among this set of coordinately regulated genes. Hepatic memory has been described for the chicken VTGII (Deeley et al 1977;Jost et al 1978) and apoVLDLII (Codina-Salada et al 1983) genes, as well as the four frog VTG genes (Wolffe and Tata 1983;Wahli and Ryffel 1985). To determine whether the VTGI and VTGIII genes also display hepatic memory at the level of RNA, we examined the kinetics of the accumulation of VTGI and VTGIII RNA following the administration of primary and secondary injections of estradiol to 1-weekold birds.…”

“…One intriguing aspect of the regulation of the estradiol-dependent induction of protein (Jost et al 1973;Luskey et al 1974;Capony and Williams 1980) and/or RNA (Gruber et al 1976;Deeley et al 1977;Jost et al 1978) for the various yolk protein genes is the phenomenon of hepatic memory. This concept derives from the observation that there is a faster onset of rapid accumulation of both RNA and protein following a secondary administration of estrogen relative to that observed following the initial exposure to the hormone.…”