Role of actin in the responses of adrenal cells to ACTH and cyclic AMP: inhibition by DNase I.
Open Access
- 1 October 1984
- journal article
- research article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 99 (4), 1335-1342
- https://doi.org/10.1083/jcb.99.4.1335
Abstract
Erythrocyte ghosts were loaded with pancreatic DNase I and fused with Y-1 adrenal tumor cells to test the possibility that this enzyme might inhibit the steroidogenic responses of the cells to ACTH and cyclic AMP. Fusion of erythrocyte ghosts loaded with DNase I, but not those containing albumin, ovalbumin, boiled DNase I, or DNase I with excess G-actin, inhibited the increase in production of 20 alpha-dihydroprogesterone produced by ACTH and dibutyryl cyclic AMP; inhibition was concentration-dependent with 50% inhibition by 3 X 10(7) molecules of DNase I per cell. It was found that inhibition by DNase I was exerted at the step in the steroidogenic pathway at which cholesterol is transported to mitochondria where steroidogenesis begins. This was shown by measuring transport of cholesterol into the inner mitochondrial membrane, by measuring the production of pregnenolone by isolated mitochondria and by demonstrating that DNase I was without effect on the conversion of pregnenolone to 20 alpha-dihydroprogesterone (an end-product of steroid synthesis). The actin content of Y-1 cells was measured by two methods based upon inhibition of DNase I and by SDS gels following centrifugation. The cells were found to contain 2-3 X 10(7) molecules of actin per cell of which two-thirds is present as G-actin. Since DNase I is known to bind to G-actin to give a one to one complex, these and other findings suggest that at least some of the G-actin in the cells may be necessary for the steroidogenic responses to ACTH and cyclic AMP.Keywords
This publication has 31 references indexed in Scilit:
- The role of microfilaments in the response of adrenal tumor cells to adrenocorticotropic hormone.Journal of Biological Chemistry, 1979
- Procedure for determination of free and total cholesterol in micro- or nanogram amounts suitable for studies with cultured cells.Journal of Lipid Research, 1978
- Selective assay of monomeric and filamentous actin in cell extracts, using inhibition of deoxyribonuclease ICell, 1978
- Preparation of protease-free and ribonuclease-free pancreatic deoxyribonuclease.Journal of Biological Chemistry, 1978
- Mechanism of corticotropin action in rat adrenal cells I. The effects of inhibitors of protein synthesis and of microfilament formation on corticosterone synthesisBiochimica et Biophysica Acta (BBA) - General Subjects, 1978
- Implication of microtubules and microfilaments in the response of the ovarian adenylate cyclase-cyclic AMP system to gonadotropins and prostaglandin E2Biochemical and Biophysical Research Communications, 1978
- Response of adrenal tumor cells to adrenocorticotropin: site of inhibition by cytochalasin BBiochemistry, 1977
- Transfer of tRNAs to somatic cells mediated by Sendai-virus-induced fusion.Proceedings of the National Academy of Sciences, 1976
- ACTH and the Metabolism of Adrenal Cell CulturesPublished by Elsevier ,1970
- Protein Biosynthesis in the Testis: II. Role of Adenosine Triphosphate (ATP) in Stimulation by GlucoseEndocrinology, 1968