Phospholipase Cgamma2 is critical for Dectin-1-mediated Ca2+ flux and cytokine production in dendritic cells.
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.
Xu
Shengli
S
Laboratory of Immunology, Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore 138668.
Huo
Jianxin
J
Lee
Koon-Guan
KG
Kurosaki
Tomohiro
T
Lam
Kong-Peng
KP
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D000818:Animals; D000074018:B-Cell CLL-Lymphoma 10 Protein; D053468:CARD Signaling Adaptor Proteins; D002118:Calcium / Q000276:immunology / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D020169:Caspases / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002473:Cell Wall / Q000276:immunology / Q000378:metabolism; D016207:Cytokines / Q000276:immunology / Q000378:metabolism*; D003713:Dendritic Cells / Q000166:cytology / Q000201:enzymology* / Q000276:immunology; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D004963:Estrenes / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D005658:Fungi / Q000276:immunology / Q000378:metabolism; D051550:I-kappa B Kinase / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D037181:Lectins, C-Type; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D051966:Phospholipase C gamma / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D015054:Zymosan / Q000494:pharmacology; D047071:beta-Glucans / Q000494:pharmacology; D000099181:Dectin-1
D048868:Adaptor Proteins, Signal Transducing; D000074018:B-Cell CLL-Lymphoma 10 Protein; D053468:CARD Signaling Adaptor Proteins; D002118:Calcium; D020169:Caspases; D016207:Cytokines; D004963:Estrenes; D048049:Extracellular Signal-Regulated MAP Kinases; D051550:I-kappa B Kinase; D037181:Lectins, C-Type; D008565:Membrane Proteins; D000074884:Mucosa-Associated Lymphoid Tissue Lymphoma Translocation 1 Protein; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D010726:Phosphodiesterase Inhibitors; D051966:Phospholipase C gamma; D011760:Pyrrolidinones; D015054:Zymosan; D047071:beta-Glucans; D000099181:Dectin-1; C488088:Bcl10 protein, mouse; C513280:Card9 protein, mouse; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C038459:curdlan; C117399:Plcg1 protein, mouse; C498509:Malt1 protein, mouse