title: Inhibition of SIK2 and SIK3 during differentiation enhances the anti-inflammatory phenotype of macrophages.
abstract: The salt-inducible kinases (SIKs) control a novel molecular switch regulating macrophage polarization. Pharmacological inhibition of the SIKs induces a macrophage phenotype characterized by the secretion of high levels of anti-inflammatory cytokines, including interleukin (IL)-10, and the secretion of very low levels of pro-inflammatory cytokines, such as tumour necrosis factor α. The SIKs, therefore, represent attractive new drug targets for the treatment of macrophage-driven diseases, but which of the three isoforms, SIK1, SIK2 or SIK3, would be appropriate to target remains unknown. To address this question, we developed knock-in (KI) mice for SIK1, SIK2 and SIK3, in which we introduced a mutation that renders the enzymes catalytically inactive. Characterization of primary macrophages from the single and double KI mice established that all three SIK isoforms, and in particular SIK2 and SIK3, contribute to macrophage polarization. Moreover, we discovered that inhibition of SIK2 and SIK3 during macrophage differentiation greatly enhanced the production of IL-10 compared with their inhibition in mature macrophages. Interestingly, macrophages differentiated in the presence of SIK inhibitors, MRT199665 and HG-9-91-01, still produced very large amounts of IL-10, but very low levels of pro-inflammatory cytokines, even after the SIKs had been reactivated by removal of the drugs. Our data highlight an integral role for SIK2 and SIK3 in innate immunity by preventing the differentiation of macrophages into a potent and stable anti-inflammatory phenotype.
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Sir James Black Centre, Dow Street, Dundee DD1 5EH, U.K.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Darling
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Sir James Black Centre, Dow Street, Dundee DD1 5EH, U.K.
authors.forename: Rachel
authors.initials: R
authors.lastname: Toth
authors.affiliation: Division of Cell Signalling and Immunology, School of Life Sciences, University of Dundee, Sir James Black Centre, Dow Street, Dundee DD1 5EH, U.K.
authors.forename: J Simon C
authors.initials: JS
authors.lastname: Arthur
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Sir James Black Centre, Dow Street, Dundee DD1 5EH, U.K. kristopher.a.clark@gmail.com.
authors.forename: Kristopher
authors.initials: K
authors.lastname: Clark
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D015870:Gene Expression; D055879:Gene Knock-In Techniques; D007113:Immunity, Innate; D007189:Indans / Q000494:pharmacology; D016753:Interleukin-10 / Q000096:biosynthesis / Q000276:immunology; D053762:Interleukin-12 Subunit p40 / Q000096:biosynthesis / Q000276:immunology; D015850:Interleukin-6 / Q000096:biosynthesis / Q000276:immunology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010641:Phenotype; D010671:Phenylurea Compounds / Q000494:pharmacology; D061251:Primary Cell Culture; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000235:genetics / Q000276:immunology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology*; D011743:Pyrimidines / Q000494:pharmacology; D019076:Transgenes; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000276:immunology
chemical_list: C577044:HG-9-91-01; C556062:IL10 protein, mouse; D007189:Indans; D053762:Interleukin-12 Subunit p40; D015850:Interleukin-6; C577045:MRT199665; D010671:Phenylurea Compounds; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D014409:Tumor Necrosis Factor-alpha; C577686:interleukin-6, mouse; D016753:Interleukin-10; D011494:Protein Kinases; C551842:salt-inducible kinase-2, human; D017346:Protein Serine-Threonine Kinases; C509080:SIK1 protein, human; C509079:SIK3 protein, human
keywords: HG-9-91-01; IL-10; TNF-α; inflammation; macrophage; salt-inducible kinase