title: The pro-atherogenic cytokine interleukin-18 induces CXCL16 expression in rat aortic smooth muscle cells via MyD88, interleukin-1 receptor-associated kinase, tumor necrosis factor receptor-associated factor 6, c-Src, phosphatidylinositol 3-kinase, Akt, c-Jun N-terminal kinase, and activator protein-1 signaling.
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.
authors.affiliation: Department of Medicine, Medicine/Cardiology, The University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA. chandraseka@uthscsa.edu
authors.forename: Bysani
authors.initials: B
authors.lastname: Chandrasekar
authors.forename: Srinivas
authors.initials: S
authors.lastname: Mummidi
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Valente
authors.forename: Devang N
authors.initials: DN
authors.lastname: Patel
authors.forename: Steven R
authors.initials: SR
authors.lastname: Bailey
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Freeman
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hatano
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tokuhisa
authors.forename: Liselotte E
authors.initials: LE
authors.lastname: Jensen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism / Q000502:physiology*; D001011:Aorta / Q000378:metabolism*; D017209:Apoptosis; D001483:Base Sequence; D000081247:CSK Tyrosine-Protein Kinase; D002448:Cell Adhesion; D049109:Cell Proliferation; D019743:Chemokines, CXC / Q000096:biosynthesis* / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004742:Enhancer Elements, Genetic; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D005799:Genes, Dominant; D053592:Interleukin-1 Receptor-Associated Kinases; D020382:Interleukin-18 / Q000378:metabolism / Q000502:physiology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000378:metabolism; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D053594:Myeloid Differentiation Factor 88; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000737:chemistry / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D011971:Receptors, Immunologic / Q000096:biosynthesis* / Q000378:metabolism / Q000502:physiology*; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism / Q000502:physiology*; D019061:src-Family Kinases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D000081247:CSK Tyrosine-Protein Kinase; D019743:Chemokines, CXC; D003609:Dactinomycin; D004791:Enzyme Inhibitors; D053592:Interleukin-1 Receptor-Associated Kinases; D020382:Interleukin-18; D048031:JNK Mitogen-Activated Protein Kinases; D008565:Membrane Proteins; D048055:Mitogen-Activated Protein Kinase 8; D053594:Myeloid Differentiation Factor 88; D016376:Oligonucleotides, Antisense; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D016760:Proto-Oncogene Proteins c-fos; D034741:RNA, Small Interfering; D011971:Receptors, Immunologic; D048029:TNF Receptor-Associated Factor 6; D018808:Transcription Factor AP-1; D019061:src-Family Kinases; C507781:Myd88 protein, rat; C494920:Akt1 protein, rat