Mechanism of induction of Δ5-3β-hydroxysteroid dehydrogenase-isomerase activity in rat adrenocortical cells by corticotropin

Rybak, Susanna M. ; Ramachandran, J. (1982) Mechanism of induction of Δ5-3β-hydroxysteroid dehydrogenase-isomerase activity in rat adrenocortical cells by corticotropin Endocrinology, 111 (2). pp. 427-433. ISSN 0013-7227

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Official URL: http://endo.endojournals.org/cgi/content/abstract/...

Related URL: http://dx.doi.org/10.1210/endo-111-2-427

Abstract

The regulation of Δ5-3β-hydroxysteroid dehydrogenase-isomerase (3β-HSD) was studied in primary cultures of rat adrenocortical cells. In the absence of ACTH, this enzymic activity was found to decay with a half-life of 3.1 days, which was similar to the half-life of the enzyme activity induced by ACTH in vitro (3.5 days). The increase in 3β-HSD activity was highly specific for ACTH and dibutyryl cAMP; the activity was not increased by other hormones known to affect adrenocortical growth or function. The induction of 3β-HSD activity by ACTH or dibutyryl cAMP required a lag period of approximately 4 h and was dependent on RNA and protein syntheses. The increase in 3β-HSD activity observed after ACTH treatment was not a result of ACTH-induced inhibition of degradation of the enzyme, nor was it due to the synthesis of a soluble intermediate which could directly activate the enzyme. ACTH stimulated the incorporation of [35S]methionine into a protein associated with 3β-HSD activity detected on polyacrylamide gels after electrophoresis of Triton X-100 extracts of adrenocortical cells. The induction of this protein by ACTH was inhibited by actinomycin D. A protein band of a partially purified preparation of rat adrenal 3β-HSD was found to comigrate with the ACTH-induced protein on sodium dodecyl sulfate-polyacrylamide gel. These results suggest that ACTH caused the de novo synthesis of 3β-HSD by a mechanism dependent on RNA synthesis.

Item Type:Article
Source:Copyright of this article belongs to Endocrine Society.
ID Code:40894
Deposited On:25 May 2011 09:34
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