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 previously identified human GR promoter and coding sequences, has been isolated and characterized. The hGR 1Ap/e sequence is approximately 31 kbp upstream of the human GR coding sequence. This sequence (2,056 bp) contains a novel promoter (the hGR 1A promoter; 1,075 bp) and untranslated exon sequence (hGR exon 1A sequence; 981 bp). Alternative splicing produces three different hGR 1A-containing transcripts, 1A1, 1A2, and 1A3. GR transcripts containing exon 1A1, 1A2, 1B, and 1C are expressed at various levels in many cancer cell lines, while the exon 1A3-containing GR transcript is expressed most abundantly in blood cell cancer cell lines. Glucocorticoid hormone treatment causes an up-regulation of exon 1A3-containing GR transcripts in CEM-C7 T-lymphoblast cells and a down-regulation of exon 1A3-containing transcripts in IM-9 B-lymphoma cells. Deoxyribonuclease I footprinting using CEM-C7 cell nuclear extract reveals four footprints in the promoter region and two intraexonic footprints. Much of the basal promoter-activating function is found in the +41/+269 sequence, which contains two deoxyribonuclease I footprints (FP5 and FP6). When this sequence is cloned into the pXP-1 luciferase reporter gene, hormone treatment causes a significant increase in luciferase activity in Jurkat T cells that are cotransfected with a GR expression vector. FP5 is an interferon regulatory factor-binding element, and it contributes significantly to basal transcription rate, but it is not activated by steroid. FP6 resembles a glucocorticoid response element and can bind GRbeta. This novel hGR 1Ap/e sequence may have future applications for the diagnosis, prognosis, and treatment of T-cell leukemia and lymphoma.
Breslin
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MB
Department of Biochemistry and Molecular Biology and the Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
Geng
C D
CD
Vedeckis
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WV
D017398:Alternative Splicing; D001483:Base Sequence; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000235:genetics; D003850:Deoxyribonuclease I; D005091:Exons; D015870:Gene Expression; D005938:Glucocorticoids / Q000494:pharmacology*; D019337:Hematologic Neoplasms / Q000737:chemistry; D006801:Humans; D050856:Interferon Regulatory Factor-1; D019169:Jurkat Cells; D016393:Lymphoma, B-Cell / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009369:Neoplasms / Q000737:chemistry; D010750:Phosphoproteins / Q000235:genetics; D016133:Polymerase Chain Reaction; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000235:genetics*; D020218:Response Elements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014407:Tumor Cells, Cultured; D020506:Untranslated Regions
D004268:DNA-Binding Proteins; D005938:Glucocorticoids; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; D010750:Phosphoproteins; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D020506:Untranslated Regions; D003850:Deoxyribonuclease I