Identification and tissue distribution of a novel rat glucocorticoid receptor splice variant.

Abstract

Glucocorticoid receptor (GR) is a steroid hormone receptor that has been shown to play important roles in diverse cellular and physiological processes. More and more evidence has revealed that the effects of glucocorticoids are mediated by the glucocorticoid receptor through genomic or nongenomic mechanisms. A growing number of glucocorticoid receptor splice variants have been identified in human tissues, but few are known in rat tissues. In this work, a novel rGR cDNA, called rGRbeta, was cloned from Sprague Dawlay (SD) rat liver. Sequence analysis revealed that the rGRbeta mRNA was 39 base pairs (bp) shorter than the rGR mRNA reported earlier. The deleted segment is located in exon 1 and encodes 13 repeated glutamine residues. Both the rGR and rGRbeta mRNAs were quantitated by Northern blot hybridization using non-homologous glucocorticoid cDNA probes. Results showed that the rGR and rGRbeta mRNAs were most abundant in the lung, the least abundant in the heart, and there were more rGR and rGRbeta mRNAs in the kidney than in the liver. The identification of rGRbeta may contribute to the understanding of the genomic or nongenomic effects of glucocorticoids.