Abstract
Dectin-1 is a C-type lectin that recognizes beta-glucan in the cell walls of fungi and plays an important role in anti-fungal immunity. It signals via tyrosine kinase Syk and adaptor protein Card9 to activate NF-kappaB leading to proinflammatory cytokine production in dendritic cells (DCs). Other than this, not much else is known of the mechanism of Dectin-1 signaling. We demonstrate here that stimulation of DCs with zymosan triggers an intracellular Ca2+ flux that can be attenuated by a blocking anti-Dectin-1 antibody or by pre-treatment of cells with the phospholipase C (PLC) gamma-inhibitor U73122, suggesting that Dectin-1 signals via a PLCgamma pathway to induce Ca2+ flux in DCs. Interestingly, treatment of DCs with particulate curdlan, which specifically engages Dectin-1, results in the phosphorylation of both PLCgamma1 and PLCgamma2. However, we show that PLCgamma2 is the critical enzyme for Dectin-1 signaling in DCs. PLCgamma2-deficient DCs have drastic impairment of Ca2+ signaling and are defective in their secretion of interleukin 2 (IL-2), IL-6, IL-10, IL-12, IL-23, and tumor necrosis factor alpha. PLCgamma2-deficient DCs also exhibit impaired activation of ERK and JNK MAPKs and AP-1 and NFAT transcription factors in response to Dectin-1 stimulation. In addition, PLCgamma2-deficient DCs are also impaired in their activation of NF-kappaB upon Dectin-1 engagement due to defective assembly of the Card9-Bcl10-Malt1 complex and impaired IKKalpha/beta activation and IkappaBalpha degradation. Thus, our data indicate that pattern recognition receptors such as Dectin-1 could elicit Ca2+ signaling and that PLCgamma2 is a critical player in the Dectin-1 signal transduction pathway.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing / genetics
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Adaptor Proteins, Signal Transducing / immunology
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Adaptor Proteins, Signal Transducing / metabolism
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Animals
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B-Cell CLL-Lymphoma 10 Protein
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CARD Signaling Adaptor Proteins
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Calcium / immunology
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Calcium / metabolism*
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Calcium Signaling / drug effects
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Calcium Signaling / physiology*
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Caspases / genetics
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Caspases / immunology
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Caspases / metabolism
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Cell Wall / immunology
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Cell Wall / metabolism
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Cytokines / immunology
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Cytokines / metabolism*
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Dendritic Cells / cytology
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Dendritic Cells / enzymology*
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Dendritic Cells / immunology
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Enzyme Activation / drug effects
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Enzyme Activation / immunology
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Estrenes / pharmacology
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Extracellular Signal-Regulated MAP Kinases / genetics
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Extracellular Signal-Regulated MAP Kinases / immunology
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Extracellular Signal-Regulated MAP Kinases / metabolism
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Fungi / immunology
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Fungi / metabolism
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I-kappa B Kinase / genetics
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I-kappa B Kinase / immunology
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I-kappa B Kinase / metabolism
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Lectins, C-Type
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Membrane Proteins / genetics
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Membrane Proteins / immunology
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Membrane Proteins / metabolism*
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Mice
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Mice, Knockout
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Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein
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NF-kappa B / genetics
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NF-kappa B / immunology
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NF-kappa B / metabolism
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NFATC Transcription Factors / genetics
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NFATC Transcription Factors / immunology
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NFATC Transcription Factors / metabolism
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Neoplasm Proteins / genetics
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Neoplasm Proteins / immunology
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Neoplasm Proteins / metabolism
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / immunology
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Nerve Tissue Proteins / metabolism*
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Phosphodiesterase Inhibitors / pharmacology
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Phospholipase C gamma / genetics
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Phospholipase C gamma / immunology
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Phospholipase C gamma / metabolism*
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Pyrrolidinones / pharmacology
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Zymosan / pharmacology
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beta-Glucans / pharmacology
Substances
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Adaptor Proteins, Signal Transducing
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B-Cell CLL-Lymphoma 10 Protein
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Bcl10 protein, mouse
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CARD Signaling Adaptor Proteins
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Card9 protein, mouse
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Cytokines
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Estrenes
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Lectins, C-Type
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Membrane Proteins
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NF-kappa B
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NFATC Transcription Factors
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Neoplasm Proteins
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Nerve Tissue Proteins
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Phosphodiesterase Inhibitors
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Pyrrolidinones
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beta-Glucans
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dectin 1
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1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione
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curdlan
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Zymosan
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I-kappa B Kinase
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Extracellular Signal-Regulated MAP Kinases
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Phospholipase C gamma
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Plcg1 protein, mouse
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Caspases
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Malt1 protein, mouse
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Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein
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Calcium