Tyrosine Phosphorylation of MyD88 Adapter-like (Mal) Is Critical for Signal Transduction and Blocked in Endotoxin Tolerance

Piao, Wenji; Song, Chang; Chen, Haiyan; Wahl, Larry M.; Fitzgerald, Katherine A.; O’Neill, Luke A. J.; Medvedev, Andrei E.

doi:10.1074/jbc.m707400200

Cited by 70 publications

(89 citation statements)

References 62 publications

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“…We found no effect of this variant on the ability of Mal to recruit TRAF6 (data not shown); however, our studies with MalE190A and those by Hill and co-workers (15) combined with the inability of the rare Mal D96N SNP to interact with MyD88 (16) highlight the fact that structural modifications to Mal can have important implications in the formation of the plasma membrane proximal signaling complex. Interestingly, whereas Mal has been reported to undergo Tyr phosphorylation (25,26), caspase-1-mediated cleavage (27), and now the physiological impact of the S180L variant, none of these events altered the ability of Mal to interact with TRAF6 in immunoprecipitation experiments because ectopically expressed single amino substitution variants were still recognized by recombinant TRAF6 (data not shown), which combined with the direct interaction of the recombinant Mal and TRAF6 proteins strongly suggests that post-translational modification is not required for the interaction to occur. This suggests therefore that there is still more to be understood as to the signaling capabilities of Mal.…”

Section: Discussionmentioning

confidence: 99%

MyD88 Adapter-like (Mal)/TIRAP Interaction with TRAF6 Is Critical for TLR2- and TLR4-mediated NF-κB Proinflammatory Responses

Verstak

Nagpal

Bottomley

et al. 2009

Journal of Biological Chemistry

183

133

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Toll/interleukin-1 (TIR)receptor-containing adapters are critical in orchestrating the different signal transduction pathways following Toll-like receptor (TLR) activation. MyD88 adapter-like (Mal), also termed TIRAP, is involved in bridging MyD88 to the receptor complex for TLR-2 and TLR4 signaling in response to bacterial infection. We have previously reported an interaction between Mal and tumor necrosis factor receptor-associated factor 6 (TRAF6) via a TRAF6-binding motif, the disruption of which inhibited TLR-mediated NF-B-luciferase reporter activity. Given the recent report of intracellular TRAM localization promoting sequential signaling in TLR4 responses, we further characterized Mal interaction with TRAF6, the cellular localization, and the outcomes of disrupting this association on TLR inflammatory responses. We found that Mal and TRAF6 directly interact in response to TLR2 and TLR4 stimulation, although membrane localization is not necessary to facilitate interaction. Critically, reconstitution of murine Mal-deficient macrophages with MalE190A, containing a mutation within the TRAF6-binding motif, fails to reconstitute the proinflammatory response to TLR2 and TLR4 ligands compared with wild type Mal. Furthermore, Mal interaction with TRAF6 mediates Ser phosphorylation of the p65 subunit of NF-B and thus controls transcriptional activation but not nuclear translocation of NF-B. This study characterizes the novel role for Mal in facilitating the direct recruitment of TRAF6 to the plasma membrane, which is necessary for TLR2-and TLR4-induced transactivation of NF-B and regulation of the subsequent pro-inflammatory response.

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Section: Discussionmentioning

confidence: 99%

MyD88 Adapter-like (Mal)/TIRAP Interaction with TRAF6 Is Critical for TLR2- and TLR4-mediated NF-κB Proinflammatory Responses

Verstak

Nagpal

Bottomley

et al. 2009

Journal of Biological Chemistry

183

133

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“…Moreover, we identified that the Y167 residue located in TIR domain of TRAM was the phospho-accepting tyrosine, and Y167 mutation of TRAM lost the activity of triggering downstream signals. It has been reported that TIRAP underwent tyrosine phosphorylation at the residues within its TIR domain following LPS stimulation, and this modification initiated a con- formational change in the TIR domain of TIRAP (12,13), thereby leading to activation of downstream signals. Tyrosine phosphorylation results in the recruitment of the phosphorylase kinase, such as Ser/Thr kinase and PI3K, to the signaling complex, a step that is essential for the activation of downstream transcription factors (11).…”

Section: Discussionmentioning

confidence: 99%

“…The myristoylation of TRAM localizes it on the plasma membrane (29), where it undergoes phosphorylation at Ser 16 and then translocates to the cytoplasm (7). TIRAP, the sorting adaptor for MyD88-dependent pathway, undergoes tyrosine phosphorylation at Tyr 86 , Tyr 106 , and Tyr 159 residues within its TIR domain following LPS stimulation, and that is required for the activation of MyD88-dependent pathway in TLR2 and TLR4 signaling (12,13). Similar to TIRAP, TRAM also bears conserved TIR domain and function as a sorting adaptor for bridging TLR4 and TRIF in TLR4 activation (4-6).…”

Section: Tram Is Tyrosine Phosphorylated Upon Lps Stimulationmentioning

confidence: 99%

“…In addition to the receptors, other components of the PRRs signaling pathways (e.g., the adaptors, also undergo tyrosine phosphorylation upon ligand engagement) (11). Tyrosine phosphorylation of TIRAP is required for the recruitment of MyD88 to TLR2 and TLR4 (12,13). TRIF and MyD88 have been shown to be tyrosine phosphorylated causing downregulation of TLR signaling (14).…”

mentioning

confidence: 99%

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Phosphatase PTPN4 Preferentially Inhibits TRIF-Dependent TLR4 Pathway by Dephosphorylating TRAM

Huai

Song

Wang

et al. 2015

The Journal of Immunology

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TLR4 recruits TRIF-related adaptor molecule (TRAM, also known as TICAM2) as a sorting adaptor to facilitate the interaction between TLR4 and TRIF and then initiate TRIF-dependent IRF3 activation. However, the mechanisms by which TRAM links downstream molecules are not fully elucidated. In this study, we show that TRAM undergoes tyrosine phosphorylation upon TLR4 activation and that is required for TLR4-induced IRF3 activation. Protein tyrosine phosphatase nonreceptor type 4 (PTPN4), a protein tyrosine phosphatase, inhibits tyrosine phosphorylation and subsequent cytoplasm translocation of TRAM, resulting in the disturbance of TRAM–TRIF interaction. Consequently, PTPN4 specifically inhibits TRIF-dependent IRF3 activation and IFN-β production in TLR4 pathway. Therefore, our results provide new insight into the TLR4 pathway and identify PTPN4 as a specific inhibitor of TRIF-dependent TLR4 pathway. Targeting PTPN4 would be beneficial for the development of new strategy to control TLR4-associated diseases without unwanted side effects.

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“…Y86A Mal-hemagglutinin (HA) and Y187A Mal-HA were as described previously (35). Mal E190A was created using Pfu Turbo (Stratagene, La Jolla, CA) and the following primers: 59-AGCTGCCTACCCACCTGA-GCTCCGATTCATGTACT-39 and 59-AGTACATGAATCGGAGCTCAG-GTGGGTAGGCAGCT-39.…”

Section: Plasmids and Reagentsmentioning

confidence: 99%

Mal Mediates TLR-Induced Activation of CREB and Expression of IL-10

Mellett

Atzei

Jackson

et al. 2011

The Journal of Immunology

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TLRs initiate immune responses by direct detection of molecular motifs that distinguish invading microbes from host cells. Five intracellular adaptor proteins, each containing a Toll/IL-1R (TIR) domain, are used by TLRs and play key roles in dictating gene expression patterns that are tailored to the invader. Such gene expression is mediated by transcription factors, and although TIR adaptor-induced activation of NF-κB and the IFN regulatory factors have been intensively studied, there is a dearth of information on the role of TIR adaptors in regulating CREB. In this paper, we describe a role for the TIR adaptor Mal in enhancing activation of CREB. Mal-deficient murine bone marrow-derived macrophages show a loss in responsiveness to TLR2 and TLR4 ligands with respect to activation of CREB. Mal-deficient cells also fail to express the CREB-responsive genes IL-10 and cyclooxygenase 2 in response to Pam2Cys-Ser-(Lys)4 and LPS. We reveal that Mal-mediated activation of CREB is dependent on Pellino3 and TNFR-associated factor 6, because CREB activation is greatly diminished in Pellino3 knockdown cells and TNFR-associated factor 6-deficient cells. We also demonstrate the importance of p38 MAPK in this pathway with the p38 inhibitor SB203580 abolishing activation of CREB in murine macrophages. MAPK-activated protein kinase 2 (MK2), a substrate for p38 MAPK, is the likely downstream mediator of p38 MAPK in this pathway, because Mal is shown to activate MK2 and inhibition of MK2 decreases TLR4-induced activation of CREB. Overall, these studies demonstrate a new role for Mal as a key upstream regulator of CREB and as a contributor to the expression of both pro- and anti-inflammatory genes.

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Tyrosine Phosphorylation of MyD88 Adapter-like (Mal) Is Critical for Signal Transduction and Blocked in Endotoxin Tolerance

Cited by 70 publications

References 62 publications

MyD88 Adapter-like (Mal)/TIRAP Interaction with TRAF6 Is Critical for TLR2- and TLR4-mediated NF-κB Proinflammatory Responses

MyD88 Adapter-like (Mal)/TIRAP Interaction with TRAF6 Is Critical for TLR2- and TLR4-mediated NF-κB Proinflammatory Responses

Phosphatase PTPN4 Preferentially Inhibits TRIF-Dependent TLR4 Pathway by Dephosphorylating TRAM

Mal Mediates TLR-Induced Activation of CREB and Expression of IL-10

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