Increased Glucocorticoid Receptor β Expression Converts Mouse Hybridoma Cells to a Corticosteroid-Insensitive Phenotype

Glucocorticoid (GC) insensitivity is a challenging clinical problem associated with many chronic inflammatory disorders and life-threatening disease progression. The molecular basis of GC insensitivity, however, is unknown. Alternative splicing of the GC receptor (GCR) pre-mRNA generates a second GCR, termed GCRβ, which does not bind GC but antagonizes the transactivating activity of the classic GCR, termed GCRα. GC-insensitive conditions have been associated with increased GCRβ expression. Whether or not increased GCRβ expression can contribute to GC insensitivity, however, remains controversial. To more precisely demonstrate the effect of GCRβ on steroid responsiveness, we virally transduced GCRβ cDNA into mouse DO-11.10 hybridoma cells, as mice are known to be deficient in the GCRβ gene. We demonstrate that viral transduction of GCRβ cDNA into mouse hybridoma cells to induce stable expression of GCRβ results in GC insensitivity of these cells. Furthermore, in such cells GCRα is complexed with GCRβ. Suc...