The human granulocyte-macrophage colony-stimulating factor gene is autonomously regulated in vivo by an inducible tissue-specific enhancer.
The granulocyte-macrophage colony-stimulating factor (GM-CSF) gene is part of a cytokine gene cluster and is directly linked to a conserved upstream inducible enhancer. Here we examined the in vitro and in vivo functions of the human GM-CSF enhancer and found that it was required for the correctly regulated expression of the GM-CSF gene. An inducible DNase I-hypersensitive site appeared within the enhancer in cell types such as T cells, myeloid cells, and endothelial cells that express GM-CSF, but not in nonexpressing cells. In a panel of transfected cells the human GM-CSF enhancer was activated in a tissue-specific manner in parallel with the endogenous gene. The in vivo function of the enhancer was examined in a transgenic mouse model that also addressed the issue of whether the GM-CSF locus was correctly regulated in isolation from other segments of the cytokine gene cluster. After correction for copy number the mean level of human GM-CSF expression in splenocytes from 11 lines of transgenic mice containing a 10.5-kb human GM-CSF transgene was indistinguishable from mouse GM-CSF expression (99% +/- 56% SD). In contrast, a 9.8-kb transgene lacking just the enhancer had a significantly reduced (P = 0.004) and more variable level of activity (29% +/- 89% SD). From these studies we conclude that the GM-CSF enhancer is required for the correct copy number-dependent expression of the human GM-CSF gene and that the GM-CSF gene is regulated independently from DNA elements associated with the closely linked IL-3 gene or other members of the cytokine gene cluster.
Cockerill
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PN
Division of Human Immunology, Hanson Centre For Cancer Research, Institute for Medical and Veterinary Science, Frome Road, Adelaide 5000, Australia. peter.cockerill@imvs.sa.gov.au
Bert
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AG
Roberts
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D
Vadas
M A
MA
D000818:Animals; D001665:Binding Sites; D002843:Chromatin / Q000378:metabolism; D016207:Cytokines / Q000235:genetics; D018983:DNA Footprinting; D003850:Deoxyribonuclease I / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D018628:Gene Dosage; D005786:Gene Expression Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D007377:Interleukin-3 / Q000235:genetics; D019169:Jurkat Cells; D051379:Mice; D008822:Mice, Transgenic; D005810:Multigene Family; D014018:Tissue Distribution; D020298:U937 Cells
D002843:Chromatin; D016207:Cytokines; D007377:Interleukin-3; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003850:Deoxyribonuclease I