Cyclic AMP and calcium in mouse mammary tumour virus expression: effects and post-transcriptional site of action
- 1 August 1990
- journal article
- research article
- Published by Bioscientifica in Journal of Molecular Endocrinology
- Vol. 5 (1) , 27-31
- https://doi.org/10.1677/jme.0.0050027
Abstract
The role of cyclic AMP (cAMP), calcium, calmodulin and protein kinase C (PKC) in the expression of both mouse mammary tumour virus (MMTV) RNA and an MMTV glycoprotein, gp58, was investigated in normal mammary epithelium in culture. None of these second messengers had any effect on MMTV RNA. Dibutyryl cAMP alone had no effect on gp58 levels but, at low concentrations (0·05–0·1 mm), it nearly doubled the induction seen with insulin, cortisol and prolactin; higher concentrations were inhibitory. Although a calcium ionophore (A23187), either alone or with hormones, was ineffective, a calcium channel blocker (verapamil) reduced hormonal induction of gp58 by 80%, and a calmodulin inhibitor (W-13) reduced it by 90%. Two PKC activators, a phorbol ester and a diacylglyceride, were ineffective alone, with hormones or with the calcium ionophore. The following conclusions can be made: (1) cAMP, calcium and calmodulin play an important role in MMTV expression, (2) these second messengers all act post-transcriptionally, since they do not affect MMTV RNA, and (3) PKC does not appear to have a role in MMTV production in normal mammary epithelium.This publication has 6 references indexed in Scilit:
- Comparative analysis of phosphorylation of translational initiation and elongation factors by seven protein kinasesJournal of Biological Chemistry, 1989
- cAMP-mediated protein phosphorylation of microsomal membranes increases mannosylphosphodolichol synthase activity.Proceedings of the National Academy of Sciences, 1987
- The relation between adenosine diphosphate‐ribosylation and mammary gland differentiationJournal of Cellular Biochemistry, 1985
- Calmodulin content of rat mammary tissue and isolated cells during pregnancy and lactationBiochemical Journal, 1984
- Cyclic AMP changes in guinea pig mammary gland and milkAmerican Journal of Physiology-Endocrinology and Metabolism, 1983
- Hormone-dependent differentiation of mammary gland in vitro.Proceedings of the National Academy of Sciences, 1965