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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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Related in: MedlinePlus

Regulation of IRAK-1 kinase activity by SHP-1.Upper Panel represents an in vitro kinase assay comparing the basal kinase activity of IRAK-1 in WT littermates versus Ptpn6me/me MØ (SHP-1−/−). A fraction of the IP was kept and subjected to a western blot as a control for equal IRAK-1 IP (2nd panel from top). Cell lysates of WT and SHP-1−/− MØs were blotted for SHP-1 to demonstrate the presence/absence of the SHP-1 protein (3rd panel from top). The membrane was stripped and reblotted for IRAK-1 to monitor its expression level in both cell lines (4th panel from top). Actin levels are shown as loading controls (bottom panel). All results are representative of at least three independent experiments.
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pntd-0000305-g001: Regulation of IRAK-1 kinase activity by SHP-1.Upper Panel represents an in vitro kinase assay comparing the basal kinase activity of IRAK-1 in WT littermates versus Ptpn6me/me MØ (SHP-1−/−). A fraction of the IP was kept and subjected to a western blot as a control for equal IRAK-1 IP (2nd panel from top). Cell lysates of WT and SHP-1−/− MØs were blotted for SHP-1 to demonstrate the presence/absence of the SHP-1 protein (3rd panel from top). The membrane was stripped and reblotted for IRAK-1 to monitor its expression level in both cell lines (4th panel from top). Actin levels are shown as loading controls (bottom panel). All results are representative of at least three independent experiments.

Mentions: To investigate the effect of SHP-1 on IRAK-1 kinase activity, we immunoprecipitated IRAK-1 from the lysates of SHP-1−/− MØs and their wildtype (WT) counterparts and subjected the IP to an IRAK-1 kinase assay. Results indicated that IRAK-1 kinase activity in SHP-1−/− cells was significantly higher compared to WT (Figure 1, top panel). The increase in IRAK-1 basal kinase activity observed in SHP-1−/− cells is not due to a differential expression of IRAK-1 as supported by loading controls provided (Figure 1, lower panels).


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)

Regulation of IRAK-1 kinase activity by SHP-1.Upper Panel represents an in vitro kinase assay comparing the basal kinase activity of IRAK-1 in WT littermates versus Ptpn6me/me MØ (SHP-1−/−). A fraction of the IP was kept and subjected to a western blot as a control for equal IRAK-1 IP (2nd panel from top). Cell lysates of WT and SHP-1−/− MØs were blotted for SHP-1 to demonstrate the presence/absence of the SHP-1 protein (3rd panel from top). The membrane was stripped and reblotted for IRAK-1 to monitor its expression level in both cell lines (4th panel from top). Actin levels are shown as loading controls (bottom panel). All results are representative of at least three independent experiments.
© Copyright Policy
Related In: Results  -  Collection

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

pntd-0000305-g001: Regulation of IRAK-1 kinase activity by SHP-1.Upper Panel represents an in vitro kinase assay comparing the basal kinase activity of IRAK-1 in WT littermates versus Ptpn6me/me MØ (SHP-1−/−). A fraction of the IP was kept and subjected to a western blot as a control for equal IRAK-1 IP (2nd panel from top). Cell lysates of WT and SHP-1−/− MØs were blotted for SHP-1 to demonstrate the presence/absence of the SHP-1 protein (3rd panel from top). The membrane was stripped and reblotted for IRAK-1 to monitor its expression level in both cell lines (4th panel from top). Actin levels are shown as loading controls (bottom panel). All results are representative of at least three independent experiments.
Mentions: To investigate the effect of SHP-1 on IRAK-1 kinase activity, we immunoprecipitated IRAK-1 from the lysates of SHP-1−/− MØs and their wildtype (WT) counterparts and subjected the IP to an IRAK-1 kinase assay. Results indicated that IRAK-1 kinase activity in SHP-1−/− cells was significantly higher compared to WT (Figure 1, top panel). The increase in IRAK-1 basal kinase activity observed in SHP-1−/− cells is not due to a differential expression of IRAK-1 as supported by loading controls provided (Figure 1, lower panels).

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