Transcriptional regulation of the expression of macrophage colony stimulating factor.
The regulatory regions for transcriptional control of the MCSF gene are unknown. We examined regulatory control in a 774-bp murine MCSF promoter transfected into MC3T3-E1 osteoblast-like and COS-7 cells. Deletion of upstream sequence from -635 increased basal activity of the promoter by at least four-fold, an increase that was maintained when PU.1, NFkappaB and Egr1/Sp1 consensus sequences were subsequently removed. Mutagenesis identified a suppressor element between -635 and -642 from the transcriptional start site and an oligonucleotide representing this sequence was retarded by nuclear cell protein. TNFalpha (1 ng/ml), PTH (5x10(-8) M), and IL-1alpha (100 pg/ml), which increased MCSF protein secretion, failed to enhance the transcriptional rate of the full-length promoter. TNFalpha was able to stimulate transcription of a heterologous reporter transfected into COS-7 containing multiple copies of the murine MCSF NFkappaB site inserted before a minimal promoter. In contrast, deletion of the same NFkappaB response element increased basal activity in the native promoter. Thus, the NFkappaB sequence may act as a negative regulator in the context of the endogenous promoter. Our results indicate that constitutive transcriptional activity conferred by the MCSF promoter may be damped by a suppressor protein. Transcriptional regulation, however, does not appear to be a major stimulatory mechanism for MCSF secretion.
Rubin
J
J
Department of Medicine, Veterans Affairs Medical Center and Emory University School of Medicine, VAMC-151, Dcatur, GA 30033, USA. jrubi02@emory.edu
Fan
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Wade
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Murphy
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Gewant
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Nanes
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Fan
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Moerenhout
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Hofstetter
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D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D016723:Bone Remodeling / Q000187:drug effects / Q000235:genetics; D019556:COS Cells; D017931:DNA Primers / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D007375:Interleukin-1 / Q000494:pharmacology; D016173:Macrophage Colony-Stimulating Factor / Q000235:genetics*; D051379:Mice; D016296:Mutagenesis; D016328:NF-kappa B / Q000235:genetics; D010281:Parathyroid Hormone / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D017931:DNA Primers; D007375:Interleukin-1; D016328:NF-kappa B; D010281:Parathyroid Hormone; D014409:Tumor Necrosis Factor-alpha; D016173:Macrophage Colony-Stimulating Factor