Abstract
Interleukin-10 (IL-10) is an anti-inflammatory cytokine that plays a key role in maintaining immune homeostasis. IL-10-mediated responses are triggered upon binding to a heterodimeric receptor complex consisting of IL-10 receptor (IL-10R)1 and IL-10R2. Engagement of the IL-10R complex activates the intracellular kinases Jak1 and Tyk2, but the exact roles of IL-10R2 and IL-10R2-associated signaling via Tyk2 remain unclear. To elucidate the contribution of IL-10R2 and its signaling to IL-10 activity, we re-evaluated IL-10-mediated responses on bone marrow-derived dendritic cells, macrophages and mast cells. By using bone marrow from IL-10R-/- mice it was revealed that IL-10-mediated responses depend on both IL-10R1 and IL-10R2 in all three cell types. On the contrary, bone marrow-derived cells from Tyk2-/- mice showed similar responses to IL-10 as wild-type cells, indicating that signaling via this IL-10R2-associated kinase only plays a limited role. Tyk2 was shown to control the amplitude of STAT3 activation and the up-regulation of downstream SOCS3 expression. SOCS3 up-regulation was found to be cell-type dependent and correlated with the lack of early suppression of LPS-induced TNF-α in dendritic cells. Further investigation of the IL-10R complex revealed that both the extracellular and intracellular domains of IL-10R2 influence the conformation of IL-10R1 and that both domains were required for transducing IL-10 signals. This observation highlights a novel role for the intracellular domain of IL-10R2 in the molecular mechanisms of IL-10R activation.
MeSH terms
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Animals
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Bone Marrow Cells / cytology
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Bone Marrow Cells / drug effects
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Bone Marrow Cells / immunology
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Cloning, Molecular
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Dendritic Cells / cytology
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Dendritic Cells / drug effects
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Dendritic Cells / immunology*
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Gene Expression
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Gene Expression Regulation
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Interleukin-10 / genetics
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Interleukin-10 / immunology*
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Interleukin-10 / pharmacology
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Lipopolysaccharides / pharmacology
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Macrophages / cytology
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Macrophages / drug effects
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Macrophages / immunology*
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Mast Cells / cytology
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Mast Cells / drug effects
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Mast Cells / immunology*
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Mice
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Mice, Inbred C57BL
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Mice, Knockout
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Nicotiana / genetics
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Nicotiana / metabolism
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Organ Specificity
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Primary Cell Culture
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Protein Binding
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Protein Interaction Domains and Motifs
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Protein Isoforms / deficiency
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Protein Isoforms / genetics
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Protein Isoforms / immunology
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Receptors, Interleukin-10 / deficiency
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Receptors, Interleukin-10 / genetics
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Receptors, Interleukin-10 / immunology*
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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STAT3 Transcription Factor / genetics
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STAT3 Transcription Factor / immunology
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Signal Transduction / immunology*
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Suppressor of Cytokine Signaling 3 Protein / genetics
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Suppressor of Cytokine Signaling 3 Protein / immunology
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TYK2 Kinase / deficiency
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TYK2 Kinase / genetics
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TYK2 Kinase / immunology*
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Tumor Necrosis Factor-alpha / genetics
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Tumor Necrosis Factor-alpha / immunology
Substances
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IL10 protein, mouse
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Lipopolysaccharides
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Protein Isoforms
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Receptors, Interleukin-10
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Recombinant Proteins
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STAT3 Transcription Factor
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Socs3 protein, mouse
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Stat3 protein, mouse
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Suppressor of Cytokine Signaling 3 Protein
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Tumor Necrosis Factor-alpha
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Interleukin-10
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TYK2 Kinase
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Tyk2 protein, mouse
Grants and funding
This work was partly funded by Synthon BV, Nijmegen, The Netherlands. There was no additional external funding received for this study.