title: Suppressor of cytokine signaling 1 inhibits IL-10-mediated immune responses.
abstract: IL-10 has proved to be a key cytokine in regulating inflammatory responses by controlling the production and function of various other cytokines. The suppressor of cytokine signaling (SOCS) gene products are a family of cytoplasmic molecules that are essential mediators for negatively regulating cytokine signaling. It has been previously shown that IL-10 induced SOCS3 expression and that forced constitutive expression of SOCS3 inhibits IL-10/STAT3 activation and LPS-induced macrophage activation. In this report, we show that, in addition to SOCS3 expression, IL-10 induces SOCS1 up-regulation in all cell lines tested, including Ba/F3 pro-B cells, MC/9 mast cells, M1 leukemia cells, U3A human fibroblasts, and primary mouse CD4(+) T cells. Induction of SOCS molecules is dependent on STAT3 activation by IL-10R1. Cell lines constitutively overexpressing SOCS proteins demonstrated that SOCS1 and SOCS3, but not SOCS2, are able to partially inhibit IL-10-mediated STAT3 activation and proliferative responses. Pretreatment of M1 cells with IFN-gamma resulted in SOCS1 induction and a reduction of IL-10-mediated STAT3 activation and cell growth inhibition. IL-10-induced SOCS is associated with the inhibition of IFN-gamma signaling in various cell types, and this inhibition is independent of C-terminal serine residues of the IL-10R, previously shown to be required for other anti-inflammatory responses. Thus, the present results show that both SOCS1 and SOCS3 are induced by IL-10 and may be important inhibitors of both IL-10 and IFN-gamma signaling. IL-10-induced SOCS1 may directly inhibit IL-10 IFN-gamma signaling, while inhibition of other proinflammatory cytokine responses may use additional IL-10R1-mediated mechanisms.
authors.affiliation: Carl C. Icahn Institute for Gene Therapy and Molecular Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA.
authors.forename: Yaozhong
authors.initials: Y
authors.lastname: Ding
authors.forename: Dongmei
authors.initials: D
authors.lastname: Chen
authors.forename: Adel
authors.initials: A
authors.lastname: Tarcsafalvi
authors.forename: Ruthie
authors.initials: R
authors.lastname: Su
authors.forename: Lihui
authors.initials: L
authors.lastname: Qin
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Bromberg
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D002455:Cell Division / Q000276:immunology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D006131:Growth Inhibitors / Q000502:physiology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000494:pharmacology; D016753:Interleukin-10 / Q000037:antagonists & inhibitors* / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008808:Mice, Inbred CBA; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D012097:Repressor Proteins; D050796:STAT3 Transcription Factor; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D000071222:Suppressor of Cytokine Signaling 1 Protein; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D014157:Transcription Factors; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D006131:Growth Inhibitors; D007166:Immunosuppressive Agents; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; C108944:SOCS1 protein, human; C106644:SOCS3 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C491590:Socs1 protein, mouse; C491411:Socs3 protein, mouse; C494087:Stat3 protein, mouse; D000071222:Suppressor of Cytokine Signaling 1 Protein; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D016753:Interleukin-10; D007371:Interferon-gamma