Modulation of TLR signaling by multiple MyD88-interacting partners including leucine-rich repeat Fli-I-interacting proteins.
Emerging evidences suggest TLR-mediated signaling is tightly regulated by a specific chain of intracellular protein-protein interactions, some of which are yet to be identified. Previously we utilized a dual-tagging quantitative proteomics approach to uncover MyD88 interactions in LPS-stimulated cells and described the function of Fliih, a leucine-rich repeat (LRR) protein that negatively regulates NF-kappaB activity. Here we characterize two distinct LRR-binding MyD88 interactors, LRRFIP2 and Flap-1, and found that both are positive regulators of NF-kappaB activity. Upon LPS stimulation, LRRFIP2 was also found to positively regulate cytokine production in macrophages, suggesting a functional role in TLR4-mediated inflammatory response. Furthermore, we observed that immediately following LPS stimulation both LRRFIP2 and Flap-1 compete with Fliih for interacting with MyD88 to activate the signaling. By using a novel multiplex quantitative proteomic approach, we found that at endogenous levels these positive and negative regulators interact with MyD88 in a timely and orderly manner to differentially mediate the NF-kappaB activity through the course of signaling from initiation to prolongation, and to repression. Based on these data, we describe a mechanistic model in which selective modulation of TLR signaling is achieved by temporal and dynamic interactions of MyD88 with its regulators.
Dai
Penggao
P
Department of Biochemistry and Biophysics.
Jeong
Sun Yong
SY
Yu
Yanbao
Y
Leng
Taohua
T
Wu
Weidong
W
Xie
Ling
L
Chen
Xian
X
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001667:Binding, Competitive / Q000276:immunology; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000378:metabolism / Q000502:physiology; D006801:Humans; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D008840:Microfilament Proteins / Q000378:metabolism* / Q000502:physiology; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism / Q000502:physiology*; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology; D011485:Protein Binding / Q000276:immunology; D016601:RNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000819:agonists / Q000378:metabolism* / Q000502:physiology; D015534:Trans-Activators
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; C098179:FLII protein, human; C000609263:FlII protein, mouse; C114370:LRRFIP1 protein, human; C120550:LRRFIP2 protein, human; C507779:MYD88 protein, human; D008840:Microfilament Proteins; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D016601:RNA-Binding Proteins; D018160:Receptors, Cytoplasmic and Nuclear; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D015534:Trans-Activators