Abstract
Steroid auto-regulation of the human glucocorticoid receptor (hGR) 1A promoter in lymphoblast cells resides largely in two DNA elements (footprints 11 and 12). We show here that c-Myb and c-Ets family members (Ets-1/2, PU.1, and Spi-B) control hGR 1A promoter regulation in T- and B-lymphoblast cells. Two T-lymphoblast lines, CEM-C7 and Jurkat, contain high levels of c-Myb and low levels of PU.1, whereas the opposite is true in IM-9 B-lymphoblasts. In Jurkat cells, overexpression of c-Ets-1, c-Ets-2, or PU.1 effectively represses dexamethasone-mediated up-regulation of an hGR 1A promoter-luciferase reporter gene, as do dominant negative c-Myb (c-Myb DNA-binding domain) or Ets proteins (Ets-2 DNA-binding domain). Overexpression of c-Myb in IM-9 cells confers hormone-dependent up-regulation to the hGR 1A promoter reporter gene. Chromatin immunoprecipitation assays show that hormone treatment causes the recruitment of hGR and c-Myb to the hGR 1A promoter in CEM-C7 cells, whereas hGR and PU.1 are recruited to this promoter in IM-9 cells. These observations suggest that the specific transcription factor that binds to footprint 12, when hGR binds to the adjacent footprint 11, determines the direction of hGR 1A promoter auto-regulation. This leads to a "molecular switch" model for auto-regulation of the hGR 1A promoter.
MeSH terms
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Apoptosis
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B-Lymphocytes / metabolism*
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Blotting, Western
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Cell Line
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Cell Lineage
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Chromatin Immunoprecipitation
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DNA-Binding Proteins / biosynthesis*
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Electroporation
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Exons
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Gene Expression Regulation*
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Genes, Dominant
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Humans
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Jurkat Cells
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Leukemia / metabolism
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Luciferases / metabolism
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Lymphocytes / metabolism
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Models, Biological
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Polymerase Chain Reaction
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Promoter Regions, Genetic*
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Protein Binding
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Protein Structure, Tertiary
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Proto-Oncogene Protein c-ets-1 / biosynthesis*
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Proto-Oncogene Protein c-ets-2 / biosynthesis*
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Proto-Oncogene Proteins / biosynthesis*
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins c-ets / metabolism
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Proto-Oncogene Proteins c-ets / physiology*
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Proto-Oncogene Proteins c-myb / metabolism
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Proto-Oncogene Proteins c-myb / physiology*
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Receptors, Glucocorticoid / genetics*
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Steroids / metabolism*
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T-Lymphocytes / cytology
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T-Lymphocytes / metabolism*
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Trans-Activators / biosynthesis*
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Trans-Activators / metabolism
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Transcription Factors / biosynthesis*
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Transfection
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Up-Regulation
Substances
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DNA-Binding Proteins
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ETS1 protein, human
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Proto-Oncogene Protein c-ets-1
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Proto-Oncogene Protein c-ets-2
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-ets
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Proto-Oncogene Proteins c-myb
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Receptors, Glucocorticoid
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Steroids
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Trans-Activators
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Transcription Factors
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proto-oncogene protein Spi-1
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SPIB protein, human
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Luciferases