Analysis of Egr-1 protein induction in murine peritoneal macrophages treated with granulocyte-macrophage colony-stimulating factor.
Transcription of early growth response gene-1 (Egr-1) is required for macrophage differentiation. Since granulocyte-macrophage colony-stimulating factor (GM-CSF) induces macrophage proliferation as well as the transcription of Egr-1 mRNA, we characterized the induction of Egr-1 protein in murine peritoneal macrophages following treatment with GM-CSF. As determined by Western blot analysis, the concentration of GM-CSF required to induce detectable Egr-1 protein in macrophages was 50 units/ml, and the inducible Egr-1 protein species was 80 kDa. Following stimulation of macrophages with GM-CSF, Egr-1 protein was detected within 25 min and reached maximum level at 70 min. The concentration of GM-CSF that was required to induce Egr-1 protein in macrophages was similar to that required to induce macrophage proliferation. A similar concentration has been detected previously in mouse serum exposed to bacterial endotoxin in vivo, suggesting that the 80 kDa Egr-1 protein may be induced in macrophages under the physiologic circumstances of pathogen invasion. Thus, our data support further study on the role of Egr-1 protein in mediating GM-CSF induction of macrophage proliferation.
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Department of Internal Medicine, Yale University School of Medicine, West Haven, Connecticut, USA.
Mitchell
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Coleman
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D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002455:Cell Division; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D051766:Early Growth Response Protein 1; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D017874:Immediate-Early Proteins; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D013864:Thioglycolates; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D017874:Immediate-Early Proteins; D013864:Thioglycolates; D014157:Transcription Factors; D016178:Granulocyte-Macrophage Colony-Stimulating Factor