title: Dendritic cell maturation requires STAT1 and is under feedback regulation by suppressors of cytokine signaling.
abstract: In this study we show that activation of STAT pathways is developmentally regulated and plays a role in dendritic cell (DC) differentiation and maturation. The STAT6 signaling pathway is constitutively activated in immature DC (iDC) and declines as iDCs differentiate into mature DCs (mDCs). However, down-regulation of this pathway during DC differentiation is accompanied by dramatic induction of suppressors of cytokine signaling 1 (SOCS1), SOCS2, SOCS3, and cytokine-induced Src homology 2-containing protein expression, suggesting that inhibition of STAT6 signaling may be required for DC maturation. In contrast, STAT1 signaling is most robust in mDCs and is not inhibited by the up-regulated SOCS proteins, indicating that STAT1 and STAT6 pathways are distinctly regulated in maturing DC. Furthermore, optimal activation of STAT1 during DC maturation requires both IL-4 and GM-CSF, suggesting that synergistic effects of both cytokines may in part provide the requisite STAT1 signaling intensity for DC maturation. Analyses of STAT1(-/-) DCs reveal a role for STAT1 in repressing CD86 expression in precursor DCs and up-regulating CD40, CD11c, and SOCS1 expression in mDCs. We further show that SOCS proteins are differentially induced by IL-4 and GM-CSF in DCs. SOCS1 is primarily induced by IL-4 through a STAT1-dependent mechanism, whereas SOCS3 is induced mainly by GM-CSF. Taken together, these results suggest that cytokine-induced maturation of DCs is under feedback regulation by SOCS proteins and that the switch from constitutive activation of the STAT6 pathway in iDCs to predominant use of STAT1 signals in mDC is mediated in part by STAT1-induced SOCS expression.
authors.affiliation: Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Sharon H
authors.initials: SH
authors.lastname: Jackson
authors.forename: Cheng-Rong
authors.initials: CR
authors.lastname: Yu
authors.forename: Rashid M
authors.initials: RM
authors.lastname: Mahdi
authors.forename: Samuel
authors.initials: S
authors.lastname: Ebong
authors.forename: Charles E
authors.initials: CE
authors.lastname: Egwuagu
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D004357:Drug Synergism; D025461:Feedback, Physiological / Q000235:genetics / Q000276:immunology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D023461:Myeloid Progenitor Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050794:STAT1 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 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation / Q000276:immunology; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008070:Lipopolysaccharides; D011506:Proteins; D012097:Repressor Proteins; D050794:STAT1 Transcription Factor; C491590:Socs1 protein, mouse; C491411:Socs3 protein, mouse; C473086:Socs6 protein, mouse; C494080:Stat1 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; D015847:Interleukin-4; D016178:Granulocyte-Macrophage Colony-Stimulating Factor