Dataset Information

Identification of binding sites for myeloid differentiation primary response gene 88 (MyD88) and Toll-like receptor 4 in MyD88 adapter-like (Mal).

ABSTRACT: Upon activation, Toll-like receptor 4 (TLR4) binds adapter proteins, including MyD88 (myeloid differentiation primary response gene 88) and Mal (MyD88 adapter-like) for its signal transduction. TLR4 and the adapter proteins each contain a Toll/Il-1 receptor domain (TIR domain). In this study we used random mutagenesis and the mammalian two-hybrid method MAPPIT (mammalian protein-protein interaction trap) to identify mutations in Mal that disrupt its interaction with TLR4 and/or MyD88. Our study shows that four potential binding sites and the AB-loop in the Mal TIR domain all contribute to formation of the TLR4-Mal-MyD88 complex. Mutations in the symmetrical back-to-back Mal homodimer interface affect Mal homodimerization and interaction with MyD88 and TLR4. Our data suggest that Mal dimerization may lead to formation of potential binding platforms on the top and the side of the Mal dimer that bind MyD88 or TLR4. Mutations that affect the interaction of Mal with MyD88 also affect NF-?B activation induced by Mal overexpression. In MAPPIT, co-expression of the MyD88 TIR domain enhances Mal dimerization and Mal binding to TLR4. Similarly, co-expression of Mal and the MyD88 TIR domain strongly promotes dimerization of the TLR4 intracellular domain in MAPPIT. The different types of TIR-TIR interactions in the TLR4-Mal-MyD88 complex thus show cooperative binding in MAPPIT. We present plausible models for the TIR-TIR interactions in the TLR4-Mal-MyD88 complex.

SUBMITTER: Bovijn C

PROVIDER: S-EPMC3636891 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

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Identification of binding sites for myeloid differentiation primary response gene 88 (MyD88) and Toll-like receptor 4 in MyD88 adapter-like (Mal).

Bovijn Celia C Desmet Anne-Sophie AS Uyttendaele Isabel I Van Acker Tim T Tavernier Jan J Peelman Frank F

The Journal of biological chemistry 20130304 17

Upon activation, Toll-like receptor 4 (TLR4) binds adapter proteins, including MyD88 (myeloid differentiation primary response gene 88) and Mal (MyD88 adapter-like) for its signal transduction. TLR4 and the adapter proteins each contain a Toll/Il-1 receptor domain (TIR domain). In this study we used random mutagenesis and the mammalian two-hybrid method MAPPIT (mammalian protein-protein interaction trap) to identify mutations in Mal that disrupt its interaction with TLR4 and/or MyD88. Our study ...[more]

PMID: 23460645

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Project description:Toll-like receptor 3 (TLR3)-mediated apoptotic changes in cancer cells are well-documented, and hence, several synthetic ligands of TLR3 are being used for adjuvant therapy, but there are reports showing a contradictory effect of TLR3 signaling, which include our previous report that had shown cell proliferation following surface localization of TLR 3. However, the underlying mechanism of cell surface localization of TLR3 and subsequent cell proliferation lacks clarity. This study addresses the TLR3 ligand-mediated signaling cascade that regulates a proliferative effect in breast cancer cells (MDA-MB-231 and T47D) challenged with TLR3 ligand in the presence of myeloid differentiation primary response 88 (MyD88) inhibitor. Evidences were obtained using immunoblotting, coimmunoprecipitation, confocal microscopy, immunocytochemistry, ELISA, and flow cytometry. Results had revealed that TLR3 ligand treatment significantly enhanced breast cancer cell proliferation marked by an upregulated expression of cyclinD1, but the same was suppressed by the addition of MyD88 inhibitor. Also, expression of interleukin 1 receptor-associated kinase 1 (IRAK1)-TNF receptor-associated factor 6 (TRAF6)-transforming growth factor beta-activated kinase 1 (TAK1) was altered in the given TLR3-signaling pathway. Inhibition of MyD88 disrupted the downstream adaptor complex and mediated signaling through the TLR3-MyD88-NF-κB (p65)-IL-6-cyclin D1 pathway. TLR3-mediated alternative signaling of the TLR3-MyD88-IRAK1-TRAF6-TAK1-TAB1-NF-κB axis leads to upregulation of IL6 and cyclin D1. This response is hypothesized to be via the MyD88 gateway that culminates in the proliferation of breast cancer cells. Overall, this study provides first comprehensive evidence on the involvement of canonical signaling of TLR3 using MyD88-cyclin D1-mediated breast cancer cell proliferation. The findings elucidated herein will provide valuable insights into understanding the TLR3-mediated adjuvant therapy in cancer.

Project description:ObjectiveTo investigate the effect of Taohong Siwu decoction (, TSD) on atherosclerosis in rats as well as investigate the underlying mechanism based on molecular docking.MethodsSixty healthy male Sprague-Dawley rats were randomly divided into 6 groups with 10 rats in each group: control group, model group, atorvastatin group (AT, 2.0 mg/kg), and TSD groups (20, 10, 5 g/kg) after 7 d of acclimation. The model of atherosclerosis was successfully established except the control group by high fat diet (HFD) and vitamin D2. Biochemical analyzers were used to detect the levels of triglyceride (TG), total cholestero (TC), low density lipoprotein-cholesterol (LDL-C) and high density lipid-cholesterol (HDL-C) in blood lipid. The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) were determined by enzyme-linked immunosorbent assay. Sudan IV staining and Hematoxylin and eosin staining (HE staining) were performed to observe the pathological changes in aortic tissue. Molecular docking technology was used to predict the best matching between the main components of TSD and the target proteins. The expression of target proteins was further detected by quantitative real time polymerase chain reaction (qRT-PCR) and Western blot analysis.ResultsThe results showed that TSD restricted atherosclerosis development and decreased the inflammatory cytokines in plasma. Molecular docking results predicted that the main components of TSD showed a strong binding ability with toll-like receptor (TLR4), myeloid differentiation primary response protein 88 (MyD88), and nuclear factor kappa-B (NF-κB). The results of qRT-PCR and Western blot analysis showed that the mRNA and protein expressions of TLR4, MyD88 and NF-κB p65 in the aorta were reduced in atorvastatin group and TSD group.ConclusionsTSD can ameliorate atherosclerosis in rats, and the underlying mechanism is supposed be related to the suppression of inflammatory response by regulating TLR4/MyD88/NF-κB signal pathway.

Dataset Information

Identification of binding sites for myeloid differentiation primary response gene 88 (MyD88) and Toll-like receptor 4 in MyD88 adapter-like (Mal).

Publications

Identification of binding sites for myeloid differentiation primary response gene 88 (MyD88) and Toll-like receptor 4 in MyD88 adapter-like (Mal).

Similar Datasets

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