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Leishmania-induced IRAK-1 inactivation is mediated by SHP-1 interacting with an evolutionarily conserved KTIM motif.

Abu-Dayyeh I, Shio MT, Sato S, Akira S, Cousineau B, Olivier M - PLoS Negl Trop Dis (2008)

Bottom Line: We also demonstrate that the SHP-1/IRAK-1 interaction occurs via an evolutionarily conserved ITIM-like motif found in the kinase domain of IRAK-1, which we named KTIM (Kinase Tyrosyl-based Inhibitory Motif).This regulatory motif appeared in early vertebrates and is not found in any other IRAK family member.We thus provide the first demonstration that a pathogen can exploit a host protein tyrosine phosphatase, namely SHP-1, to directly inactivate IRAK-1 through a generally conserved KTIM motif.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada.

ABSTRACT
Parasites of the Leishmania genus can rapidly alter several macrophage (MØ) signalling pathways in order to tame down the innate immune response and inflammation, therefore favouring their survival and propagation within their mammalian host. Having recently reported that Leishmania and bacterial LPS generate a significantly stronger inflammatory response in animals and phagocytes functionally deficient for the Src homology 2 domain-containing protein tyrosine phosphatase (SHP-1), we hypothesized that Leishmania could exploit SHP-1 to inactivate key kinases involved in Toll-like receptor (TLR) signalling and innate immunity such as IL-1 receptor-associated kinase 1 (IRAK-1). Here we show that upon infection, SHP-1 rapidly binds to IRAK-1, completely inactivating its intrinsic kinase activity and any further LPS-mediated activation as well as MØ functions. We also demonstrate that the SHP-1/IRAK-1 interaction occurs via an evolutionarily conserved ITIM-like motif found in the kinase domain of IRAK-1, which we named KTIM (Kinase Tyrosyl-based Inhibitory Motif). This regulatory motif appeared in early vertebrates and is not found in any other IRAK family member. Our study additionally reveals that several other kinases (e.g. Erk1/2, IKKalpha/beta) involved in downstream TLR signalling also bear KTIMs in their kinase domains and interact with SHP-1. We thus provide the first demonstration that a pathogen can exploit a host protein tyrosine phosphatase, namely SHP-1, to directly inactivate IRAK-1 through a generally conserved KTIM motif.

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Effect of pharmacological inhibition of IRAK-1 on MØ NO production.(A) IRAK-1 was immunoprecipitated from SHP-1−/− MØ lysates and incubated (1 h, RT) with increasing concentrations of the IRAK-1 inhibitor. A kinase assay was then performed to show functionality of the inhibitor. Data are representative of three experiments. (B) NO assay showing that the IRAK-1 inhibitor blocks, in a dose-dependent manner, basal production of NO by SHP-1−/− cells as well as LPS-mediated (O/N stimulation) NO production in both WT and SHP-1−/− MØs.
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pntd-0000305-g004: Effect of pharmacological inhibition of IRAK-1 on MØ NO production.(A) IRAK-1 was immunoprecipitated from SHP-1−/− MØ lysates and incubated (1 h, RT) with increasing concentrations of the IRAK-1 inhibitor. A kinase assay was then performed to show functionality of the inhibitor. Data are representative of three experiments. (B) NO assay showing that the IRAK-1 inhibitor blocks, in a dose-dependent manner, basal production of NO by SHP-1−/− cells as well as LPS-mediated (O/N stimulation) NO production in both WT and SHP-1−/− MØs.

Mentions: The biological relevance of this regulatory interaction between IRAK-1 and SHP-1 was investigated using the ability of N-(2-Morpholinylethyl)-2-(3-nitrobenzoylamido)-benzimidazole, a potent IRAK-1 inhibitor [19], to reduce NO production in WT and SHP-1−/− MØs. As mentioned earlier, SHP-1 deficiency in MØs results in an increase in NF-κB and AP-1 activity [7]–[9] leading to NO production at basal level and in response to LPS when compared to WT [8]. Addition of the IRAK-1 inhibitor abrogated IRAK-1 activity in a dose-dependent manner (Figure 4A), and was paralleled by a reduction of basal NO production in SHP-1−/− cells and in LPS-mediated NO production in both cell lines (Figure 4B). In addition to demonstrating the essential role of IRAK-1 signalling in NO generation, our data also shows that SHP-1-mediated IRAK-1 regulation is critical for the control of MØ activation.


Leishmania-induced IRAK-1 inactivation is mediated by SHP-1 interacting with an evolutionarily conserved KTIM motif.

Abu-Dayyeh I, Shio MT, Sato S, Akira S, Cousineau B, Olivier M - PLoS Negl Trop Dis (2008)

Effect of pharmacological inhibition of IRAK-1 on MØ NO production.(A) IRAK-1 was immunoprecipitated from SHP-1−/− MØ lysates and incubated (1 h, RT) with increasing concentrations of the IRAK-1 inhibitor. A kinase assay was then performed to show functionality of the inhibitor. Data are representative of three experiments. (B) NO assay showing that the IRAK-1 inhibitor blocks, in a dose-dependent manner, basal production of NO by SHP-1−/− cells as well as LPS-mediated (O/N stimulation) NO production in both WT and SHP-1−/− MØs.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2596967&req=5

pntd-0000305-g004: Effect of pharmacological inhibition of IRAK-1 on MØ NO production.(A) IRAK-1 was immunoprecipitated from SHP-1−/− MØ lysates and incubated (1 h, RT) with increasing concentrations of the IRAK-1 inhibitor. A kinase assay was then performed to show functionality of the inhibitor. Data are representative of three experiments. (B) NO assay showing that the IRAK-1 inhibitor blocks, in a dose-dependent manner, basal production of NO by SHP-1−/− cells as well as LPS-mediated (O/N stimulation) NO production in both WT and SHP-1−/− MØs.
Mentions: The biological relevance of this regulatory interaction between IRAK-1 and SHP-1 was investigated using the ability of N-(2-Morpholinylethyl)-2-(3-nitrobenzoylamido)-benzimidazole, a potent IRAK-1 inhibitor [19], to reduce NO production in WT and SHP-1−/− MØs. As mentioned earlier, SHP-1 deficiency in MØs results in an increase in NF-κB and AP-1 activity [7]–[9] leading to NO production at basal level and in response to LPS when compared to WT [8]. Addition of the IRAK-1 inhibitor abrogated IRAK-1 activity in a dose-dependent manner (Figure 4A), and was paralleled by a reduction of basal NO production in SHP-1−/− cells and in LPS-mediated NO production in both cell lines (Figure 4B). In addition to demonstrating the essential role of IRAK-1 signalling in NO generation, our data also shows that SHP-1-mediated IRAK-1 regulation is critical for the control of MØ activation.

Bottom Line: We also demonstrate that the SHP-1/IRAK-1 interaction occurs via an evolutionarily conserved ITIM-like motif found in the kinase domain of IRAK-1, which we named KTIM (Kinase Tyrosyl-based Inhibitory Motif).This regulatory motif appeared in early vertebrates and is not found in any other IRAK family member.We thus provide the first demonstration that a pathogen can exploit a host protein tyrosine phosphatase, namely SHP-1, to directly inactivate IRAK-1 through a generally conserved KTIM motif.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada.

ABSTRACT
Parasites of the Leishmania genus can rapidly alter several macrophage (MØ) signalling pathways in order to tame down the innate immune response and inflammation, therefore favouring their survival and propagation within their mammalian host. Having recently reported that Leishmania and bacterial LPS generate a significantly stronger inflammatory response in animals and phagocytes functionally deficient for the Src homology 2 domain-containing protein tyrosine phosphatase (SHP-1), we hypothesized that Leishmania could exploit SHP-1 to inactivate key kinases involved in Toll-like receptor (TLR) signalling and innate immunity such as IL-1 receptor-associated kinase 1 (IRAK-1). Here we show that upon infection, SHP-1 rapidly binds to IRAK-1, completely inactivating its intrinsic kinase activity and any further LPS-mediated activation as well as MØ functions. We also demonstrate that the SHP-1/IRAK-1 interaction occurs via an evolutionarily conserved ITIM-like motif found in the kinase domain of IRAK-1, which we named KTIM (Kinase Tyrosyl-based Inhibitory Motif). This regulatory motif appeared in early vertebrates and is not found in any other IRAK family member. Our study additionally reveals that several other kinases (e.g. Erk1/2, IKKalpha/beta) involved in downstream TLR signalling also bear KTIMs in their kinase domains and interact with SHP-1. We thus provide the first demonstration that a pathogen can exploit a host protein tyrosine phosphatase, namely SHP-1, to directly inactivate IRAK-1 through a generally conserved KTIM motif.

Show MeSH
Related in: MedlinePlus