Size, Complexity and Abundance of a Specific Poly(A)‐Containing RNA of Liver from Male Xenopus Induced to Vitellogenin Synthesis by Estrogen

Abstract

Estrogen treatment of Xenopus males leads to the appearance of a new species of poly(A)-containing RNA in the liver, at a stage when large amounts of the estrogen-induced yolk precursor protein, vitellogenin, is produced. This estrogen-induced RNA sediments at 28 S and migrates on gels in aqueous solution with an apparent molecular weight of 2.0 x lo6. Contour length measurements under denaturing conditions in the electron microscope reveal a molecular weight of 2.34 x lo6 compared to the mouse 28-S rRNA.Labeling experiments show that the estrogen-induced RNA has a higher stability than the average liver poly(A)-containing RNA and represents 10 -20 of the poly(A)-containing RNA in the cytoplasm after 24 h of labeling.Hybridization of complementary DNA, synthesized on the isolated estrogen-induced RNA, with its template suggests a complexity corresponding to a single species of poly(A)-containing RNA of such a high molecular weight. Hybridization of the complementary DNA with cytoplasmic poly(A)-containing RNA from estrogen-treated Xenopus males and control toads show that the estrogen-induced RNA constitutes 12 -15 % of all cytoplasmic poly(A)-containing RNA, and is at least 2000-fold less abundant in untreated males.Size, complexity and abundance of the estrogen-induced RNA are characteristics expected for a mRNA coding for vitellogenin.

Mr 25 000 protein, a substrate for protein serine/threonine kinases, is identified as a part of Xenopus laevis vitellogenin B1

“…In oviparous vertebrates, vitellogenin expression usually occurs in the liver under the control of estrogen (Wahli et al 1976(Wahli et al , 1981. However, the EST sequences of vitellogenin B1 identified in this study were not from Xenopus liver but rather from the heart and lung.…”

“…Vitellogenin is a sex-restricted yolk precursor protein in oviparous vertebrates (Bergink & Wallace 1974;Wiley & Wallace 1981). The synthesis of this large phospholipoglycoprotein is induced in the liver by estrogen (Wahli et al 1976(Wahli et al , 1981. Although the existence of two families and four subtypes of vitellogenin have been shown in Xenopus, the complete sequence has been determined only for vitellogenin A2 (Wahli et al 1981;Walker et al 1984;Wallace et al 1990).…”

Differential stability of Drosophila embryonic mRNAs during subsequent larval development.

“…One of the most poorly understood posttranscriptional controls is that which defines the stability of specific mRNA sequences. The importance of turnover rate in controlling mRNA abundance, and thus gene expression, is best illustrated by the observation that many of the mRNAs that encode the most highly abundant cell type-specific polypeptides are preferentially stabilized over other mRNAs present within the same cytoplasm (6,21,25,29,44).…”

“…One of the most poorly understood posttranscriptional controls is that which defines the stability of specific mRNA sequences. The importance of turnover rate in controlling mRNA abundance, and thus gene expression, is best illustrated by the observation that many of the mRNAs that encode the most highly abundant cell type-specific polypeptides are preferentially stabilized over other mRNAs present within the same cytoplasm (6,21,25,29,44).The stability of specific eucaryotic mRNAs has most often been determined by assaying for the presence of particular mRNAs after treating cells with the transcriptional inhibitor actinomycin D (4,13,25,34,43,46). However, this kind of analysis is subject to several possible artifacts.…”

Rudolf Weber (1922–2015): a driving force in the transition of developmental biology into a molecular and cellular science

“…He was helped in this endeavor by his outstanding electron microscopist Toni Wyler and by a series of extremely talented PhD students, all of whom later held independent group leader positions in various countries and institutions: Gerhart Ryffel (graduated 1973), Peter Wellauer (1973), Ueli Schibler (1975, Otto Hagenbüchle (1976), Walter Wahli (1977, and Barbara K. Felber (1981). 1 After initial studies on the transcriptional reactions of various Xenopus tissues during metamorphosis (Hagenbüchle et al 1976;Ryffel and Weber 1971;Ryffel and Weber 1973;Stadler and Weber 1970), they decided to study the induction of vitellogenin synthesis by estrogen in adult male Xenopus liver (Wahli et al 1976). The vitellogenin genes turned out to be the most complex genes analyzed at the time.…”