Enrichment of the Poly (A) Sequence and Lack of Enhancement of Total RNA Synthesis in Cultured Xenopus Hepatocytes by Estradio1-17β

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The effect of estradio1-17β on RNA synthesis and the amounts of total RNA and polyadenylic acid were determined in primary cultures of Xenopus laevis liver parenchymal cells. Results showed that estradiol did not alter the RNA content significantly; control cells contained 11.9±0.34 μg and estradiol-treated cells 12.4±0.17 μg per 10⁶ cells on day 2 of estradiol treatment, and 22.0±0.61 μg and 24.0±1.09 μg on day 5. Hybridization with [³H]poly(U) revealed that estradiol increased the poly (A) content about 1.2-fold more than in the controls on day 2 and 1.6-fold on day 5 of estradiol treatment. The actual rate of RNA synthesis was estimated from analyses of the kinetics of [³H]adenosine incorporation into the ATP pool and into RNA. The initial rate of incorporation of ATP into RNA on day 5 of estradiol treatment was 29.38 pmol/min/10⁶ cells and the rate of the controls of 29.35. Subsequent accumulation kinetics of [³H]adenosine into RNA showed no difference between estradiol and the control cells. Thus, estradiol did not alter the rate of total RNA synthesis and the total RNA content significantly, but it did increase the poly(A) content.