title: Up-regulation of TNF-alpha secretion by cigarette smoke is mediated by Egr-1 in HaCaT human keratinocytes.
abstract: Many epidemiologic studies have pointed to a significant association between cigarette smoking and inflammatory skin disease such as psoriasis. Cigarette smoke induces expression of regulators of inflammation such as interleukin (IL)-1, IL-6, IL-8 and tumor necrosis factor (TNF)-alpha. It was recently demonstrated that early growth response-1 (Egr-1) transcription factor is significantly up-regulated in the skin lesions of patients with psoriasis. The mechanism by which cigarette smoke extract (CSE) regulates inflammatory cytokine expression in keratinocyte was still unknown. The aim of this study was to investigate the signalling of CSE-induced Egr-1 expression and the role for Egr-1 in CSE-induced TNF-alpha expression. Cytotoxicity of CSE in HaCaT cells was measured by thiazolyl blue tetrazolium bromide (MTT) assay. CSE-induced Egr-1 expression was investigated by western blot, luciferase reporter assay and confocal microscopy. TNF-alpha expression was measured by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay. Involvement of Egr-1 in CSE-induced TNF-alpha secretion was determined by using Egr-1 specific siRNA. CSE increases the Egr-1 expression, promoter activity and its nuclear translocation in human HaCaT keratinocytes. CSE activates mitogen-activated protein kinase (MAPK) pathways including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). Up-regulation of Egr-1 expression by CSE stimulation was found to be inhibited by an ERK and JNK but not p38 inhibitor. CSE increases TNF-alpha expression and secretion. This increase is mediated by CSE-induced Egr-1 expression. Our results showed that CSE induces Egr-1 expression via MAPK pathway in human keratinocytes and TNF-alpha expression by Egr-1. This pathway may contribute to the development of inflammatory disease such as psoriasis.
authors.affiliation: Laboratory of Cell Signaling and Nanomedicine, Department of Dermatology and Division of Brain Korea 21 Project for Biomedical Science, Korea University College of Medicine, Seoul, Korea.
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Jeong
authors.forename: Jae Hong
authors.initials: JH
authors.lastname: Park
authors.forename: Ji Na
authors.initials: JN
authors.lastname: Kim
authors.forename: Yoon-Hee
authors.initials: YH
authors.lastname: Park
authors.forename: Soon Young
authors.initials: SY
authors.lastname: Shin
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.forename: Young Chul
authors.initials: YC
authors.lastname: Kye
authors.forename: Sang Wook
authors.initials: SW
authors.lastname: Son
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D051766:Early Growth Response Protein 1 / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology; D012907:Smoking; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
chemical_list: C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D048049:Extracellular Signal-Regulated MAP Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases