NF-kappa B p50 regulates C/EBP alpha expression and inflammatory cytokine-induced neutrophil production.
NF-kappaB is a key transcriptional inducer of the inflammatory response in mature myeloid cells, and also stimulates cell survival, but its role in immature myeloid cell development has not been well characterized. C/EBPalpha is required for the development of monocytic and granulocytic myeloid cells from early progenitors, and NF-kappaB and C/EBPbeta cooperatively induce several inflammatory mediators. Having found that C/EBPalpha binds NF-kappaB p50 preferentially compared with NF-kappaB p65, we have now investigated myelopoiesis in nfkb1(-/-) mice lacking NF-kappaB p50. Absence of p50 leads to a significant reduction in the number of granulocytic progenitors, CFU-granulocyte, obtained with G-CSF or GM-CSF in vitro and reduces neutrophil production in vivo in response to G-CSF, with preservation of monopoiesis in vitro in response to cytokines or LPS. To gain insight into the mechanism underlying reduced granulopoiesis in the absence of NF-kappaB p50, we assessed the expression of several myeloid regulatory proteins in lineage-negative, immature myeloid cells. Although PU.1, C/EBPbeta, and STAT3 levels were unchanged, C/EBPalpha protein and RNA levels were reduced approximately 3-fold in the absence of NF-kappaB p50. In addition, NF-kappaB p50 and C/EBPalpha bound the endogenous C/EBPalpha promoter in a chromatin immunoprecipitation assay, and NF-kappaB p50 trans activated the C/EBPalpha promoter, alone or in cooperation with C/EBPalpha. Despite reduction of C/EBPalpha, G-CSFR and M-CSFR levels were maintained in total marrow and in lineage-negative cells. Together, these data indicate that acute inflammation not only activates mature myeloid cells, but also stimulates neutrophil production via NF-kappaB p50 induction of C/EBPalpha transcription.
Wang
Dehua
D
Division of Pediatric Oncology, Johns Hopkins University, Baltimore, MD 21231, USA.
Paz-Priel
Ido
I
Friedman
Alan D
AD
D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism / Q000502:physiology*; D006410:Hematopoiesis / Q000235:genetics / Q000276:immunology*; D018836:Inflammation Mediators / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D052002:NF-kappa B p50 Subunit / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D041681:NIH 3T3 Cells; D009504:Neutrophils / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000276:immunology; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D013234:Stem Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism
D022763:CCAAT-Enhancer-Binding Protein-alpha; D016207:Cytokines; D018836:Inflammation Mediators; D052002:NF-kappa B p50 Subunit