Dexamethasone-mediated induction of mouse mammary tumor virus RNA: a system for studying glucocorticoid action

Area of Science:

• Molecular Biology
• Virology
• Endocrinology

Background:

• Mouse mammary tumor virus (MMTV) is a retrovirus associated with mammary tumors in mice.
• Glucocorticoids, like dexamethasone, are known to influence gene expression and cellular processes.

Purpose of the Study:

• To investigate the mechanism by which dexamethasone stimulates MMTV production.
• To determine the role of glucocorticoid receptors in this stimulation.

Main Methods:

• Using cell cultures derived from GR mouse mammary carcinomas.
• Treating cells with dexamethasone and measuring intracellular virus-specific RNA accumulation.
• Assessing the dependency of RNA accumulation on RNA, DNA, and protein synthesis.

Main Results:

• Dexamethasone treatment led to a rapid accumulation of intracellular MMTV-specific RNA.
• This accumulation was dependent on RNA synthesis but not DNA or protein synthesis.
• The effect appears to be mediated by specific and saturable glucocorticoid receptors.

Conclusions:

• The accumulation of MMTV RNA is a primary response to dexamethasone.
• Dexamethasone treatment likely accelerates the rate of MMTV RNA synthesis.