title: Role of CLIC4 in the host innate responses to bacterial lipopolysaccharide.
abstract: Chloride intracellular channel (CLIC) 4 has diverse functions in membrane trafficking, apoptosis, angiogenesis and cell differentiation. CLIC4 is abundantly expressed in macrophages, but its role in innate immune functions is unclear. Here, we show that primary murine macrophages express increased amounts of CLIC4 after exposure to bacterial lipopolysaccharide (LPS). Endogenous CLIC4 level was significantly elevated in the brain, heart, lung, kidney, liver and spleen after LPS injection of mice. Stable macrophage lines overexpressing CLIC4 produced more TNF, IL-6, IL-12 and CCL5 than mock transfectants when exposed to LPS. To explore the role of CLIC4 in vivo, we generated CLIC4-null mice. These mice were protected from LPS-induced death, and had reduced serum levels of inflammatory cytokines. Upon infection with Listeria monocytogenes, CLIC4-deficient mice were impaired in their ability to clear infection, and their macrophages responded to Listeria by producing less inflammatory cytokines and chemokines than the WT controls. When challenged with LPS in vitro, deletion of clic4 gene had little effect on MAPK and NF-κB activation, but led to a reduced accumulation of phosphorylated interferon response factor 3 (IRF3) within macrophages. Conversely, overexpression of CLIC4 enhanced LPS-mediated IRF3. Thus, these findings suggest that CLIC4 is an LPS-induced product that can serve as a positive regulator of LPS signaling.
authors.affiliation: Department of Microbiology and Immunology, Weill Cornell Medical College, NY 10065, USA.
authors.forename: Guoan
authors.initials: G
authors.lastname: He
authors.forename: Yao
authors.initials: Y
authors.lastname: Ma
authors.forename: Szu-Yi
authors.initials: SY
authors.lastname: Chou
authors.forename: Huihong
authors.initials: H
authors.lastname: Li
authors.forename: Chingwen
authors.initials: C
authors.lastname: Yang
authors.forename: Jen-Zen
authors.initials: JZ
authors.lastname: Chuang
authors.forename: Ching-Hwa
authors.initials: CH
authors.lastname: Sung
authors.forename: Aihao
authors.initials: A
authors.lastname: Ding
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D018925:Chemokines / Q000097:blood / Q000276:immunology; D018118:Chloride Channels / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D016207:Cytokines / Q000097:blood / Q000276:immunology / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects; D005838:Genotype; D007113:Immunity, Innate; D050838:Interferon Regulatory Factor-3 / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology* / Q000378:metabolism; D008089:Listeria monocytogenes / Q000276:immunology / Q000472:pathogenicity; D008088:Listeriosis / Q000276:immunology / Q000382:microbiology; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D024101:Mitochondrial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012772:Shock, Septic / Q000276:immunology; D015398:Signal Transduction
chemical_list: C479423:CLIC protein, mouse; D018925:Chemokines; D018118:Chloride Channels; D016207:Cytokines; D050838:Interferon Regulatory Factor-3; D008070:Lipopolysaccharides; D024101:Mitochondrial Proteins; D016328:NF-kappa B; D020928:Mitogen-Activated Protein Kinases