Glucocorticoid-mediated destabilization of cyclin D3 mRNA involves RNA-protein interactions in the 3'-untranslated region of the mRNA.

EDUARDO GARCÍA GRAS; CHI, P; THOMPSON, E A

JOURNAL OF BIOLOGICAL CHEMISTRY

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Año: 2000 vol. 275 p. 22001 - 22008

0021-9258

Glucocorticoids regulate the expression of the G(1) progression factor, cyclinD3. Cyclin D3 messenger RNA (CcnD3 mRNA) stability decreases rapidly when murine T lymphoma cells are treated with the synthetic glucocorticoid dexamethasone.Basal stability of CcnD3 mRNA is regulated by sequences within the 3´-untranslated region (3´-UTR). RNA-protein interactions occurring within theCcnD3 3´-UTR have been analyzed by RNA electrophoretic mobility shift assay.Three sites of RNA-protein interaction have been mapped using this approach.These elements include three pyrimidine-rich domains of 25, 26, and 37nucleotides. When the cyclin D3 3´-UTR was stably overexpressed, the endogenousCcnD3 mRNA was no longer regulated by dexamethasone. Likewise, overexpression ofa 215-nucleotide transgene that contains the 26- and 37-nucleotide elementsblocks glucocorticoid inhibition of CcnD3 mRNA expression. These observationssuggest that the 215-nucleotide 3´-UTR element may act as a molecular decoy,competing for proteins that bind to the endogenous transcript and thereby attenuating glucocorticoid responsiveness. UV-cross-linking experiments showed that two proteins of approximate molecular weight 37,000 and 52,000 bind to this 3´-UTR element.