Ea. Garcia-gras et al., Glucocorticoid-mediated destabilization of cyclin D3 mRNA involves RNA-protein interactions in the 3 '-untranslated region of the mRNA, J BIOL CHEM, 275(29), 2000, pp. 22001-22008
Glucocorticoids regulate the expression of the G(1) progression factor, cyc
lin D3, Cyclin D3 messenger RNA (CcnDS mRNA) stability decreases rapidly wh
en murine T lymphoma cells are treated with the synthetic glucocorticoid de
xamethasone. Basal stability of CcnDS mRNA is regulated by sequences within
the 3'-untranslated region (3'-UTR), RNA-protein interactions occurring wi
thin the CcnD3 3'-UTR have been analyzed by RNA electrophoretic mobility sh
ift assay, Three sites of RNA-protein interaction have been mapped using th
is approach, These elements include three pyrimidine-rich domains of 25, 26
, and 37 nucleotides. When the cyclin D3 3'-UTR was stably overexpressed, t
he 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 express
ion. These observations suggest that the 215-nucleotide 3'-UTR element may
act as a molecular decoy, competing for proteins that bind to the endogenou
s transcript and thereby attenuating glucocorticoid responsiveness. W-cross
-linking experiments showed that two proteins of approximate molecular weig
ht 37,000 and 52,000 bind to this 3'-UTR element.