Interaction of DJ-1 with Lyn is essential for IgE-mediated stimulation of human mast cells

Publication date: Available online 13 October 2017
Source:Journal of Allergy and Clinical Immunology
Author(s): Do-Kyun Kim, Michael A. Beaven, Dean D. Metcalfe, Ana Olivera
BackgroundDJ-1 is a redox-sensitive protein with multiple roles in cell homeostasis whose levels are altered in mast cell (MC)-related disorders. However, whether DJ-1 can regulate human MC function is unknown.ObjectiveWe sought to investigate the potential role of DJ-1 in the responses of human MCs to antigen stimulation.MethodsDJ-1 was silenced in human CD34⁺-derived and LAD2 MCs using lentiviral sh-RNA constructs. Release of β-hexosaminidase, PGD2 and GM-CSF and changes in reactive oxygen species (ROS) levels were measured after FcεRI engagement. Enzymatic assays, sucrose density gradient centrifugation, immunoprecipitations, dot and Western blots, and confocal imaging were performed for signaling, cellular localization and co-association studies.ResultsDJ-1 knockdown substantially reduced mediator release as well as Lyn and Syk kinase activation and signaling by mechanisms which appeared largely unrelated to DJ-1 antioxidant activity. Upon FcεRI activation, non-oxidized rather than oxidized DJ-1 translocated to lipid rafts where it associated with Lyn, an interaction that appeared critical for maximal Lyn activation and initiation of signaling. Using purified recombinant proteins, we demonstrated that DJ-1 bound to Lyn directly but no other Src kinases, and this interaction was specific for human but not mouse proteins. In addition, DJ-1 reduced SHP-2 phosphatase activity by scavenging ROS thus preventing Syk dephosphoryation and perpetuating MC signaling.ConclusionWe demonstrate a novel role for DJ-1 in the early activation of Lyn by FcεRI that is essential for human MC responses and which provides the basis for an alternative target in allergic diseases therapy.

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Teaser

We demonstrate a previously unrecognized interaction between DJ-1 and the Src kinase Lyn in antigen-activated human mast cells that is essential for maximal Lyn activation and the release of bioactive allergic and inflammatory mediators.


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