Abstract
We recently demonstrated that the chemokine CXCL16 is expressed in aortic smooth muscle cells (ASMC) and induces ASMC adhesion and proliferation (Chandrasekar, B., Bysani, S., and Mummidi, S. (2004) J. Biol. Chem. 279, 3188-3196). Here we reort that interleukin (IL)-18 positively regulates CXCL16 transcription in rat ASMC. We characterized the cis-regulatory region of CXCL16 and identified a functional activator protein-1 (AP-1) binding motif. Deletion or mutation of this site attenuated IL-18-mediated CXCL16 promoter activity. Gel shift, supershift, and chromatin immunoprecipitation assays confirmed AP-1-dependent CXCL16 expression. CXCL16 promoter-reporter activity was increased by constitutively active c-Fos and c-Jun and decreased by dominant negative or antisense c-Fos and c-Jun. Src kinase inhibitors PP1 and PP2, phosphatidylinositol 3-kinase (PI3K) inhibitors wortmannin and LY294002, Akt inhibitor, the c-Jun N-terminal kinase (JNK) inhibitor SP600125, antisense JNK and dominant negative MyD88, interleukin-1 receptor-associated kinase (IRAK)-1, IRAK4, and phosphatidylinositol 3-kinase expression all attenuated IL-18-mediated AP-1 binding and reporter activity, CXCL16 promoter-reporter activity, and CXCL16 expression. Thus IL-18 induced CXCL16 expression via a MyD88 --> IRAK1-IRAK4-TRAF6 (tumor necrosis factor receptor-associated factor 6) --> c-Src--> PI3K --> Akt --> JNK --> AP-1 pathway. Importantly, IL-18 stimulated ASMC proliferation in a CXCL16-dependent manner. These data provide for the first time a mechanism of IL-18-mediated CXCL16 gene transcription and CXCL16-dependent ASMC proliferation and suggest a role for IL-18-CXCL16 cross-talk in atherogenesis and restenosis following angioplasty.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adaptor Proteins, Signal Transducing
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Amino Acid Motifs
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Animals
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Antigens, Differentiation / metabolism
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Antigens, Differentiation / physiology*
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Aorta / metabolism*
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Apoptosis
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Base Sequence
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CSK Tyrosine-Protein Kinase
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Cell Adhesion
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Cell Proliferation
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Chemokines, CXC / biosynthesis*
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Chemokines, CXC / metabolism
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Dactinomycin / pharmacology
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Dose-Response Relationship, Drug
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Enhancer Elements, Genetic
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Enzyme Inhibitors / pharmacology
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Gene Expression Regulation*
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Genes, Dominant
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Interleukin-1 Receptor-Associated Kinases
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Interleukin-18 / metabolism
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Interleukin-18 / physiology*
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JNK Mitogen-Activated Protein Kinases / metabolism
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JNK Mitogen-Activated Protein Kinases / physiology*
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Membrane Proteins / biosynthesis*
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Membrane Proteins / metabolism
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Mitogen-Activated Protein Kinase 8 / metabolism
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Models, Genetic
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Myeloid Differentiation Factor 88
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Myocytes, Smooth Muscle / metabolism*
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Oligonucleotides, Antisense / chemistry
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Oligonucleotides, Antisense / pharmacology
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Phosphatidylinositol 3-Kinases / metabolism
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Phosphatidylinositol 3-Kinases / physiology*
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Phosphoinositide-3 Kinase Inhibitors
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Protein Kinases / metabolism
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Protein Kinases / physiology*
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Protein Serine-Threonine Kinases / metabolism
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Protein Serine-Threonine Kinases / physiology*
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Protein-Tyrosine Kinases / metabolism
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Protein-Tyrosine Kinases / physiology*
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins / physiology*
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Proto-Oncogene Proteins c-akt
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Proto-Oncogene Proteins c-fos / metabolism
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RNA, Small Interfering / metabolism
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Rats
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Receptors, Immunologic / biosynthesis*
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Receptors, Immunologic / metabolism
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Receptors, Immunologic / physiology*
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TNF Receptor-Associated Factor 6 / metabolism
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TNF Receptor-Associated Factor 6 / physiology*
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Time Factors
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Transcription Factor AP-1 / metabolism
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Transcription Factor AP-1 / physiology*
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src-Family Kinases
Substances
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Adaptor Proteins, Signal Transducing
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Antigens, Differentiation
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Chemokines, CXC
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Enzyme Inhibitors
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Interleukin-18
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Membrane Proteins
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Myd88 protein, rat
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Myeloid Differentiation Factor 88
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Oligonucleotides, Antisense
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Phosphoinositide-3 Kinase Inhibitors
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-fos
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RNA, Small Interfering
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Receptors, Immunologic
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TNF Receptor-Associated Factor 6
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Transcription Factor AP-1
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Dactinomycin
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Protein Kinases
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Protein-Tyrosine Kinases
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CSK Tyrosine-Protein Kinase
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src-Family Kinases
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Akt1 protein, rat
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Interleukin-1 Receptor-Associated Kinases
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Protein Serine-Threonine Kinases
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Proto-Oncogene Proteins c-akt
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinase 8