title: CMRF-35-like molecule 3 preferentially promotes TLR9-triggered proinflammatory cytokine production in macrophages by enhancing TNF receptor-associated factor 6 ubiquitination.
abstract: TLRs are critical innate immune sensors in the induction of proinflammatory cytokines to eliminate invading pathogens. However, the mechanisms for the full activation of TLR-triggered innate immune response need to be fully understood. The murine CMRF-35-like molecule (CLM)-3 is a representative of CLM family belonging to the Ig superfamily. Considering that CLM-3 is selectively expressed in macrophages and the roles of CLM members in innate immune response remain unclear, in this study we investigated the role of CLM-3 in the regulation of TLR-triggered innate response. We found that CLM-3 was an endosome/lysosome-localized molecule, and was downregulated in macrophages by stimulation with TLR9 ligand, but not TLR4 and TLR3 ligands. Interestingly, CLM-3 selectively promoted production of TNF-α and IL-6 in macrophages triggered by TLR9, but not TLR4 or TLR3. CLM-3 enhanced activation of MAPKs and NF-κB pathways in TLR9-triggered macrophages. Furthermore, CLM-3-transgenic mice were generated, and CLM-3 expression was confirmed by mAb against CLM-3 that we prepared. Accordingly, the macrophages derived from CLM-3-transgenic mice were more sensitive to TLR9 ligand stimulation, with more pronounced production of TNF-α, IL-6, and increased activation of MAPKs and NF-κB pathways. Moreover, ubiquitination of TNFR-associated factor 6, a crucial signaling transducer of TLR-triggered MAPKs and NF-κB activation, was found to be significantly promoted by CLM-3 in macrophages. Collectively, the endosome/lysosome-localized CLM-3 can promote full activation of TLR9-triggered innate responses by enhancing TNFR-associated factor 6 ubiquitination and subsequently activating MAPKs and NF-κB.
authors.affiliation: National Key Laboratory of Medical Immunology and Institute of Immunology, Second Military Medical University, Shanghai 200433, China.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Wu
authors.forename: Xuhui
authors.initials: X
authors.lastname: Zhu
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.forename: Taoyong
authors.initials: T
authors.lastname: Chen
authors.forename: Mingjin
authors.initials: M
authors.lastname: Yang
authors.forename: Ming
authors.initials: M
authors.lastname: Yao
authors.forename: Xingguang
authors.initials: X
authors.lastname: Liu
authors.forename: Boquan
authors.initials: B
authors.lastname: Jin
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Wang
authors.forename: Xuetao
authors.initials: X
authors.lastname: Cao
mesh_terms: D000818:Animals; D002460:Cell Line; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D018836:Inflammation Mediators / Q000502:physiology*; D015850:Interleukin-6 / Q000096:biosynthesis*; D020935:MAP Kinase Signaling System / Q000276:immunology; D017737:Macrophages, Peritoneal / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011971:Receptors, Immunologic / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism*; D051217:Toll-Like Receptor 9 / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*; D054875:Ubiquitination / Q000276:immunology*; D015854:Up-Regulation / Q000276:immunology
chemical_list: C555645:CLM-3 protein, mouse; D018836:Inflammation Mediators; D015850:Interleukin-6; D011971:Receptors, Immunologic; C495371:TLR9 protein, human; D048029:TNF Receptor-Associated Factor 6; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9; D014409:Tumor Necrosis Factor-alpha