title: Transcriptional and posttranscriptional regulation of CXCL8/IL-8 gene expression induced by connective tissue growth factor.
abstract: Connective tissue growth factor (CTGF), a CCN family member, is a secreted protein regulating cellular functions, including fibrosis, apoptosis, adhesion, migration, differentiation, proliferation, angiogenesis, and chondrogenesis. CTGF increases proinflammatory factor production; however, inflammatory cytokine regulation by CTGF is poorly understood. The aim of this study was to identify novel biological functions and elucidate the functional mechanisms of CTGF. Specifically, the study focused on the ability of CTGF-primed monocytes to secrete interleukin 8 (CXCL8/IL-8) and determined the signaling pathways involved in CTGF-induced CXCL8/IL-8 gene regulation during inflammation. We transfected wild-type or mutant CXCL8/IL-8 promoter-derived luciferase reporter constructs into 293T cells to examine the effect of CTGF on the CXCL8/IL-8 promoter. The results showed that the activator protein-1 and nuclear factor κB binding sites of the CXCL8/IL-8 promoter are essential for CTGF-induced CXCL8/IL-8 transcription. Moreover, the CTGF-induced activation of p38 mitogen-activated protein kinase (MAPK), c-Jun-N-terminal kinase, and extracellular signal-regulated kinase (ERK) is involved in this process. In addition, adenosine-uridine-rich elements (AREs) of the CXCL8/IL-8 3'-untranslated region (3'-UTR) reduce CXCL8/IL-8 mRNA stability. To investigate whether CTGF regulates CXCL8/IL-8 gene expression at the posttranscriptional level, we transfected 293 cells with serial luciferase constructs containing different segments of the CXCL8/IL-8 3'-UTR and then stimulated the cells with CTGF. The results suggested that CTGF stabilized luciferase mRNA and increased luciferase activity by regulating the CXCL8/IL-8 3'-UTR. Moreover, the p38 MAPK pathway may contribute to CTGF-induced CXCL8/IL-8 mRNA stabilization.
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chien-Huang
authors.initials: CH
authors.lastname: Lin
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.|Department of Medical Research, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan.
authors.forename: Yuan-Hung
authors.initials: YH
authors.lastname: Wang
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Chen
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yu-Liang
authors.initials: YL
authors.lastname: Lin
authors.affiliation: School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: Bing-Chang
authors.initials: BC
authors.lastname: Chen
authors.affiliation: Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan. mcchen@tmu.edu.tw.|Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, No. 250 Wu-Hsing Street, Taipei, 110, Taiwan. mcchen@tmu.edu.tw.
authors.forename: Mei-Chieh
authors.initials: MC
authors.lastname: Chen
mesh_terms: D020413:3' Untranslated Regions; D002460:Cell Line; D055513:Connective Tissue Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics* / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D009000:Monocytes / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D016209:Interleukin-8; D016328:NF-kappa B; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D055513:Connective Tissue Growth Factor; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases
keywords: 3′-UTR; AP-1; CTGF; CXCL8/IL-8; ERK; Fibrosis; Inflammation; JNK; NF-κB; p38 MAPK