Effects of Estradiol on In Vitro Nucleoside Incorporation and Methylation of Rat Uterine Ribonucleic Acid[1]

Abstract

The in vitro nucleoside incorporation and methylation of uterine RNA was examined by incubating immature rat uteri with either ³H-uridine, ³H-uridine-³H-cytidine, and/or ¹⁴C-methyl-methionine. Radioactivity was determined in extracted RNA which was fractionated by gel electrophoresis or by differential solubility in zine acetate or lithium chloride. Estradiol (E₂)-treated uteri respond by showing a maximum in vitro incorporation of nucleosides into total RNA and high M.W. RNA within one hr of in vivo treatment. Nucleoside incorporation into low M.W. RNA increased gradually throughout the first 3 hrs of a 4-hr hormone treatment period. E₂ in vivo also caused increased in vitro methylation of total, high, and low M.W. uterine RNA fractions. Methylation of all fractions increased through the first 3 hrs of hormone treatment, but greater methylation of low M.W. RNA was apparent. The data indicate that in vivo E₂ treatment stimulates an initial transitory stage of in vitro nucleoside incorporation into uterine RNA followed by a more prolonged interval of RNA methylation.

Key words

Estradiol - Uterus (Rat) - RNA - Nucleosides - Methylation - Methyl-methionine

1 This investigation was supported in part by research grant GB 8386 from the National Science Foundation. Paper No. 4474 of the Journal Series of the North Carolina State University Agricultural Experiment Station.

1 This investigation was supported in part by research grant GB 8386 from the National Science Foundation. Paper No. 4474 of the Journal Series of the North Carolina State University Agricultural Experiment Station.

2 Present address: Biology Department, University of North Carolina at Greensboro, Greensboro, North Carolina 2.7412