Kruppel-like Factor 4 Is a Mediator of Proinflammatory Signaling in Macrophages

• Published in: The Journal of biological chemistry Vol. 280; no. 46; pp. 38247 - 38258
• Main Authors: Feinberg, Mark W., Cao, Zhuoxiao, Wara, Akm Khyrul, Lebedeva, Maria A., SenBanerjee, Sucharita, Jain, Mukesh K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18-11-2005; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Binding Sites; Blotting, Northern; Blotting, Western; Cell Line; Cytokines - metabolism; DNA - chemistry; DNA - metabolism; Down-Regulation; Enzyme-Linked Immunosorbent Assay; Gene Deletion; Inflammation; Interferon-gamma - metabolism; Kruppel-Like Transcription Factors - metabolism; Kruppel-Like Transcription Factors - physiology; Lipopolysaccharides - metabolism; Macrophage Activation; Macrophages - metabolism; Mice; Models, Biological; Monocytes - metabolism; Mutation; Nitric Oxide Synthase Type II - metabolism; Nitrites - chemistry; Oligonucleotides, Antisense - chemistry; p300-CBP Transcription Factors - metabolism; Phosphorylation; Plasminogen Activator Inhibitor 1 - metabolism; Promoter Regions, Genetic; Protein Binding; Protein Structure, Tertiary; RNA, Messenger - metabolism; Signal Transduction; Smad3 Protein - metabolism; Transcription Factor RelA - metabolism; Transcription, Genetic; Transfection; Transforming Growth Factor beta - metabolism; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M509378200

Activation of macrophages is important in chronic inflammatory disease states such as atherosclerosis. Proinflammatory cytokines such as interferon-γ (IFN-γ), lipopolysaccharide (LPS), or tumor necrosis factor-α can promote macrophage activation. Conversely, anti-inflammatory factors such as transforming growth factor-β1 (TGF-β1) 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-γ, LPS, or tumor necrosis factor-α and decreased by TGF-β1 in macrophages. Overexpression of KLF4 in J774a macrophages induced the macrophage activation marker inducible nitric-oxide synthase and inhibited the TGF-β1 and Smad3 target gene plasminogen activator inhibitor-1 (PAI-1). Conversely, KLF4 knockdown markedly attenuated the ability of IFN-γ, LPS, or IFN-γ plus LPS to induce the iNOS promoter, whereas it augmented macrophage responsiveness to TGF-β1 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-γ and LPS. We further provide evidence that KLF4 interacts with the NF-κB family member p65 (RelA) to cooperatively induce the iNOS promoter. In contrast, KLF4 inhibited the TGF-β1/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.