Glucocorticoid-mediated destabilization of cyclin D3 mRNA involves RNA-protein interactions in the 3'-untranslated region of the mRNA.
Glucocorticoids regulate the expression of the G(1) progression factor, cyclin D3. 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 the CcnD3 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 37 nucleotides. When the cyclin D3 3'-UTR was stably overexpressed, the endogenous CcnD3 mRNA was no longer regulated by dexamethasone. Likewise, overexpression of a 215-nucleotide transgene that contains the 26- and 37-nucleotide elements blocks glucocorticoid inhibition of CcnD3 mRNA expression. These observations suggest 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.
Garcia-Gras
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Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, Texas 77555-0645, USA.
Chi
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Thompson
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D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D056743:Cyclin D3; D016213:Cyclins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D051379:Mice; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D020413:3' Untranslated Regions; C534696:CCND3 protein, human; C534697:Ccnd3 protein, mouse; D056743:Cyclin D3; D016213:Cyclins; D005938:Glucocorticoids; D012333:RNA, Messenger