Estrogen-induced synthesis of a specific uterine protein.

Abstract

Use of inhibitors of protein synthesis has revealed that the early metabolic re- sponses to estrogen depend on synthesis of protein.Puromycin-and cycloheximide-sensitive changes in the metabolism of lipid, RNA, and glucose are seen in the first hour after treatment with estrogen,1-3 and before estrogen stimulates over-all synthesis of protein.2The implications of these earlier studies are clear: (1) in less than 1 hr, estrogen induces the synthesis of protein essential to the develop- ment of the hormone response; (2) the newly made protein(s) is small in amount, contributing little to the picture of net protein synthesis.This paper presents direct evidence for the presence of such a protein in rat uteri stimulated with estradiol.Experimental Procedure.-TenHoltzman rats, 21-23 days old and weighing about 50 gm, were used in each experimental group.Estradiol-17j3 (5 ,ug in 0.5 ml 0.154 M NaCl) or saline was in- jected intraperitoneally 0.5, 1, 2, or 4 hr before killing.The excised uteri were placed in 3 ml of Eagle's HeLa tissue culture medium containing H3-leucine (60 ,uc, 1 c/mmole, Schwarz) or C11 reconstituted protein hydrolyzate (40 4c, 80-180 mc/mmole, Schwarz).The uteri were incu- bated at 370C for 1 hr under an atmosphere of 95% 02-5% C02.In some experiments actino-