Multiple promoters exist in the human GR gene, one of which is activated by glucocorticoids

A new human GR gene sequence (hGR 1Ap/e), which is distinct from the previo usly identified human GR promoter and coding sequences, has been isolated a nd characterized. The hGR 1Ap/e sequence is approximately 31 kbp upstream o f the human GR coding sequence. This sequence (2,056 bp) contains a novel p romoter (the hGR 1A promoter; 1,075 bp) and untranslated exon sequence (hGR exon 1A sequence; 981 bp). Alternative splicing produces three different h GR 1A-containing transcripts, 1A1, 1A2, and 1A3. GR transcripts containing exon 1 All, 1A2, 1B, and IC are expressed at various levels in many cancer cell lines, while the exon 1A3-containing GR transcript is expressed most a bundantly in blood cell cancer cell lines. Glucocorticoid hormone treatment causes an upregulation of exon 1A3-containing GR transcripts in CEM-C7 T-l ymphoblast cells and a down-regulation of exon 1A3-containing transcripts i n IM-9 B-lymphoma cells. Deoxyribonuclease I footprinting using CEM-C7 cell nuclear extract reveals four footprints in the promoter region and two int raexonic footprints. Much of the basal promoter-activating function is foun d in the +41/+269 sequence, which contains two deoxyribonuclease I footprin ts (FP5 and FP6). When this sequence is cloned into the pXP-1 luciferase re porter gene, hormone treatment causes a significant increase in luciferase activity in Jurkat T cells that are cotransfected with a GR expression vect or. FP5 is an interferon regulatory factor-binding element, and it contribu tes significantly to basal transcription rate, but it is not activated by s teroid. FP6 resembles a glucocorticoid response element and can bind GR bet a. This novel hGR 1Ap/e sequence may have future applications for the diagn osis, prognosis, and treatment of T-cell leukemia and lymphoma.