RESUMO
Activation of innate immune sensors by endogenous DNA and RNA can lead to autoimmune and autoinflammatory diseases. Quantification of the unperturbed phosphoprotein content in immune cells provides insight into the spontaneous activity of immune signaling pathways triggered by nucleic acid recognition. Here, we present a phosphoflow protocol for measuring phosphoproteins in mouse models of autoimmunity that incorporates strategies to preserve native phosphoprotein levels during sample collection and to reliably detect low signaling activity common in chronic disease states. For complete details on the use and execution of this protocol, please refer to Jütte et al. (2021).
Assuntos
Doenças Autoimunes , Ácidos Nucleicos , Animais , Doenças Autoimunes/genética , Autoimunidade , Camundongos , Fosfoproteínas , Transdução de Sinais/fisiologiaRESUMO
Intercellular transmission of the second messenger 2',3'-cGAMP, synthesized by the viral DNA sensor cGAMP synthase (cGAS), is a potent mode of bystander activation during host defense. However, whether this mechanism also contributes to cGAS-dependent autoimmunity remains unknown. Here, using a murine bone marrow transplantation strategy, we demonstrate that, in Trex1 -/- -associated autoimmunity, cGAMP shuttling from radioresistant to immune cells induces NF-κB activation, interferon regulatory factor 3 (IRF3) phosphorylation, and subsequent interferon signaling. cGAMP travel prevented myeloid cell and lymphocyte death, promoting their accumulation in secondary lymphoid tissue. Nonetheless, it did not stimulate B cell differentiation into autoantibody-producing plasmablasts or aberrant T cell priming. Although cGAMP-mediated bystander activation did not induce spontaneous organ disease, it did trigger interface dermatitis after UV light exposure, similar to cutaneous lupus erythematosus. These findings reveal that, in Trex1-deficiency, intercellular cGAMP transfer propagates cGAS signaling and, under conducive conditions, causes tissue inflammation.
