SEQUENCES OF RNA AND PROTEIN SYNTHESIS DURING EARLY ESTROGEN ACTION

Abstract

Evidence is presented to demonstrate that, during the 4-hour uterine response to estrogen, over-all RNA synthesis is accelerated prior to acceleration or protein synthesis. Concomitant with the early rise in uterine RNA synthesis following estrogenic stimulation, a small "hump" rise in protein synthesis occurs by 1 hr. Such a pattern of estrogen-induced synthesis of uterine protein holds until 2 1/2-3 hr, at which time a rapid, more extensive phase of protein synthesis occurs. Actinomycin D suppresses estrogen-induced synthesis of RNA to levels below those of controls, but protein synthesis in this case is restricted to control values. Since actinomycin D in hormone-free controls limits protein synthesis to lower levels, and since combined estrogen-puromycin-actinomycin D treatments give maximum inhibition of RNA and protein synthesis, evidence exists for a component of uterine hormone response which is not sensitive to actinomycin D, but is sensitive to puromycin. The findings hint that an early action of estrogen on the uterus involves induction of activation of protein synthesis which underwrites DNA-dependent RNA synthesis, and thereby controls the following more extensive phase of protein synthesis. The mechanism for this awaits elucidation.