title: Disabled-2 is a negative immune regulator of lipopolysaccharide-stimulated Toll-like receptor 4 internalization and signaling.
abstract: Toll-like receptor 4 (TLR4) plays a pivotal role in the host response to lipopolysaccharide (LPS), a major cell wall component of Gram-negative bacteria. Here, we elucidated whether the endocytic adaptor protein Disabled-2 (Dab2), which is abundantly expressed in macrophages, plays a role in LPS-stimulated TLR4 signaling and trafficking. Molecular analysis and transcriptome profiling of RAW264.7 macrophage-like cells expressing short-hairpin RNA of Dab2 revealed that Dab2 regulated the TLR4/TRIF pathway upon LPS stimulation. Knockdown of Dab2 augmented TRIF-dependent interferon regulatory factor 3 activation and the expression of subsets of inflammatory cytokines and interferon-inducible genes. Dab2 acted as a clathrin sponge and sequestered clathrin from TLR4 in the resting stage of macrophages. Upon LPS stimulation, clathrin was released from Dab2 to facilitate endocytosis of TLR4 for triggering the TRIF-mediated pathway. Dab2 functions as a negative immune regulator of TLR4 endocytosis and signaling, supporting a novel role for a Dab2-associated regulatory circuit in controlling the inflammatory response of macrophages to endotoxin.
authors.affiliation: Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Kwei-Shan, Taoyuan 333, Taiwan, Republic of China.
authors.forename: Wei-Shan
authors.initials: WS
authors.lastname: Hung
authors.affiliation: Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan, Republic of China.|Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan, Republic of China.
authors.forename: Pin
authors.initials: P
authors.lastname: Ling
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung 404, Taiwan, Republic of China.
authors.forename: Ju-Chien
authors.initials: JC
authors.lastname: Cheng
authors.affiliation: Department of Family Medicine, Chang Gung Memorial Hospital, Kweishan, Taoyuan 333, Taiwan, Republic of China.
authors.forename: Shy-Shin
authors.initials: SS
authors.lastname: Chang
authors.affiliation: Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Kwei-Shan, Taoyuan 333, Taiwan, Republic of China.|Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Kwei-Shan, Taoyuan 333, Taiwan, Republic of China.|Molecular Medicine Research Center, Chang Gung University, Kwei-Shan, Taoyuan 333, Taiwan, Republic of China.|Department of Laboratory Medicine, Chang Gung Memorial Hospital, Kwei-Shan, Taoyuan 333, Taiwan, Republic of China.
authors.forename: Ching-Ping
authors.initials: CP
authors.lastname: Tseng
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism*; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D019921:Biotinylation; D002966:Clathrin / Q000378:metabolism; D004731:Endotoxins; D007249:Inflammation; D008070:Lipopolysaccharides; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D000067996:RAW 264.7 Cells; D034741:RNA, Small Interfering / Q000378:metabolism; D018805:Sepsis / Q000382:microbiology; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D051017:Apoptosis Regulatory Proteins; D002966:Clathrin; D004731:Endotoxins; D008070:Lipopolysaccharides; D034741:RNA, Small Interfering; D051197:Toll-Like Receptor 4; C478773:Dab2 protein, mouse; C476286:Ticam1 protein, mouse; C493487:Tlr4 protein, mouse