ACTH Regulation of Adrenal mRNA Coding for Total and Specific Adrenal Proteins

Abstract

The effects in vivo ACTH administration on the synthesis of mRNA coding for total adrenal proteins and for protein E a specific marker of ACTH action, have been studied. After 4 h of in vivo ACTH treatment, protein E is one of the major translational products. Its electrophoretic characteristics in a 2D gel acrylamide system are defined (molecular mass = 36,000 daltons, pHi = 7). We have investigated the effects of ACTH on both poly(A)-RNA coding for total adrenal proteins, and non-poly(A)-RNA. The time course of these effects is different: the effect on mRNA is maximal at 48 h whereas the effect on non-poly(A)-RNA continues to increase until the end of the experiment (5 days). In vitro translocational assays of mRNA indicate that the highest efficiency (protein synthesis/µg of mRNA) is observed after 4 h of ACTH treatment in vivo. After 5 days this efficiency is similar to that of mRNA extracted from non ACTH-treated rats.