title: Kruppel-like factor 4 is a mediator of proinflammatory signaling in macrophages.
abstract: Activation of macrophages is important in chronic inflammatory disease states such as atherosclerosis. Proinflammatory cytokines such as interferon-gamma (IFN-gamma), lipopolysaccharide (LPS), or tumor necrosis factor-alpha can promote macrophage activation. Conversely, anti-inflammatory factors such as transforming growth factor-beta1 (TGF-beta1) can decrease proinflammatory activation. The molecular mediators regulating the balance of these opposing effectors remain incompletely understood. Herein, we identify Kruppel-like factor 4 (KLF4) as being markedly induced in response to IFN-gamma, LPS, or tumor necrosis factor-alpha and decreased by TGF-beta1 in macrophages. Overexpression of KLF4 in J774a macrophages induced the macrophage activation marker inducible nitric-oxide synthase and inhibited the TGF-beta1 and Smad3 target gene plasminogen activator inhibitor-1 (PAI-1). Conversely, KLF4 knockdown markedly attenuated the ability of IFN-gamma, LPS, or IFN-gamma plus LPS to induce the iNOS promoter, whereas it augmented macrophage responsiveness to TGF-beta1 and Smad3 signaling. The KLF4 induction of the iNOS promoter is mediated by two KLF DNA-binding sites at -95 and -212 bp, and mutation of these sites diminished induction by IFN-gamma and LPS. We further provide evidence that KLF4 interacts with the NF-kappaB family member p65 (RelA) to cooperatively induce the iNOS promoter. In contrast, KLF4 inhibited the TGF-beta1/Smad3 induction of the PAI-1 promoter independent of KLF4 DNA binding through a novel antagonistic competition with Smad3 for the C terminus of the coactivator p300/CBP. These findings support an important role for KLF4 as a regulator of key signaling pathways that control macrophage activation.
authors.affiliation: Program in Cardiovascular Transcriptional Biology, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. mfeinberg@rics.bwh.harvard.edu
authors.forename: Mark W
authors.initials: MW
authors.lastname: Feinberg
authors.forename: Zhuoxiao
authors.initials: Z
authors.lastname: Cao
authors.forename: Akm Khyrul
authors.initials: AK
authors.lastname: Wara
authors.forename: Maria A
authors.initials: MA
authors.lastname: Lebedeva
authors.forename: Sucharita
authors.initials: S
authors.lastname: Senbanerjee
authors.forename: Mukesh K
authors.initials: MK
authors.lastname: Jain
mesh_terms: D000818:Animals; D001665:Binding Sites; D015152:Blotting, Northern; D015153:Blotting, Western; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D015536:Down-Regulation; D004797:Enzyme-Linked Immunosorbent Assay; D017353:Gene Deletion; D007249:Inflammation; D007371:Interferon-gamma / Q000378:metabolism; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism / Q000502:physiology*; D008070:Lipopolysaccharides / Q000378:metabolism; D008262:Macrophage Activation; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D009000:Monocytes / Q000378:metabolism; D009154:Mutation; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry; D016376:Oligonucleotides, Antisense / Q000737:chemistry; D010766:Phosphorylation; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D051900:Smad3 Protein / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D050880:p300-CBP Transcription Factors / Q000378:metabolism
chemical_list: D016207:Cytokines; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D008070:Lipopolysaccharides; D009573:Nitrites; D016376:Oligonucleotides, Antisense; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; C498144:Rela protein, mouse; D051900:Smad3 Protein; C508961:Tgfb1 protein, mouse; D051996:Transcription Factor RelA; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D004247:DNA; D052247:Nitric Oxide Synthase Type II; D050880:p300-CBP Transcription Factors