RESUMEN
The DNA-mediated innate immune response underpins anti-microbial defenses and certain autoimmune diseases. Here we used immunoprecipitation, mass spectrometry, and RNA sequencing to identify a ribonuclear complex built around HEXIM1 and the long non-coding RNA NEAT1 that we dubbed the HEXIM1-DNA-PK-paraspeckle components-ribonucleoprotein complex (HDP-RNP). The HDP-RNP contains DNA-PK subunits (DNAPKc, Ku70, and Ku80) and paraspeckle proteins (SFPQ, NONO, PSPC1, RBM14, and MATRIN3). We show that binding of HEXIM1 to NEAT1 is required for its assembly. We further demonstrate that the HDP-RNP is required for the innate immune response to foreign DNA, through the cGAS-STING-IRF3 pathway. The HDP-RNP interacts with cGAS and its partner PQBP1, and their interaction is remodeled by foreign DNA. Remodeling leads to the release of paraspeckle proteins, recruitment of STING, and activation of DNAPKc and IRF3. Our study establishes the HDP-RNP as a key nuclear regulator of DNA-mediated activation of innate immune response through the cGAS-STING pathway.
Asunto(s)
ADN/inmunología , Herpesvirus Humano 8/inmunología , Inmunidad Innata , ARN Largo no Codificante/inmunología , Proteínas de Unión al ARN/inmunología , Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/inmunología , Proteínas de Unión al Calcio/metabolismo , ADN/genética , ADN/metabolismo , Proteínas de Unión al ADN , Células HEK293 , Células HeLa , Interacciones Huésped-Patógeno , Células Endoteliales de la Vena Umbilical Humana/inmunología , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Células Endoteliales de la Vena Umbilical Humana/virología , Humanos , Factor 3 Regulador del Interferón/genética , Factor 3 Regulador del Interferón/inmunología , Factor 3 Regulador del Interferón/metabolismo , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/inmunología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Autoantígeno Ku/genética , Autoantígeno Ku/inmunología , Autoantígeno Ku/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/inmunología , Proteínas de la Membrana/metabolismo , Complejos Multiproteicos , Proteínas Asociadas a Matriz Nuclear/genética , Proteínas Asociadas a Matriz Nuclear/inmunología , Proteínas Asociadas a Matriz Nuclear/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/inmunología , Proteínas Nucleares/metabolismo , Nucleotidiltransferasas/genética , Nucleotidiltransferasas/inmunología , Nucleotidiltransferasas/metabolismo , Factores de Transcripción de Octámeros/genética , Factores de Transcripción de Octámeros/inmunología , Factores de Transcripción de Octámeros/metabolismo , Factor de Empalme Asociado a PTB/genética , Factor de Empalme Asociado a PTB/inmunología , Factor de Empalme Asociado a PTB/metabolismo , Unión Proteica , Interferencia de ARN , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Transducción de Señal , Factores de Transcripción , TransfecciónRESUMEN
OBJECTIVE: Anti-MDA5 antibody positive dermatomyositis (DM) and clinically amyopathic DM (CADM) often develop into rapidly progressive interstitial lung disease, but their pathogenesis remains unclear. We observed that sera from DM/CADM patients immunoprecipitated a common 110 kDa polypeptide. We investigated this autoantigen and its clinical significance. METHODS: Autoantibodies were screened in 333 patients with various connective tissue diseases (CTDs) and 20 healthy controls (HCs) by immunoprecipitation with [35S]methionine-labeled HeLa cells. Immunoabsorbent column chromatography was used to purify the reactive autoantigen which was subsequently analyzed by peptide mass fingerprinting. RESULTS: Anti-110 kDa antibody was detected in sera from 27 DM/CADM patients, but not in sera from other CTD patients or HCs. All patients with anti-110 kDa antibody had anti-MDA5 antibody. The maximum KL-6 levels in anti-110 kDa antibody-positive patients were higher than in anti-110 kDa antibody-negative patients, and all anti-MDA5-antibody-positive patients who showed the recurrence of DM/CADM were anti-110 kDa antibody-positive. The corresponding autoantigen was identified as splicing factor proline/glutamine-rich protein (SFPQ). In some cases, anti-SFPQ antibody was detected at diagnosis (early-detected group), but in other cases, it appeared during the disease course (delayed-detected group). The diagnosis timing of DM/CADM showed seasonal patterns according to the timing of anti-SFPQ antibody appearance. Specifically, 77% (10/13) of patients were diagnosed between August and October in the early-detected group, while 57% (8/14) of patients were diagnosed between January and March in the delayed-detected group. CONCLUSIONS: Some anti-MDA5 antibody-positive patients had an antibody to SFPQ, which is known to play a role in innate immune responses. Anti-SFPQ antibody may be involved in the chronic disease course of DM/CADM. The diagnosis timing of DM/CADM in anti-MDA5 antibody-positive patients showed seasonal patterns according to the timing of anti-SFPQ antibody appearance. These findings may provide new insights into the pathogenesis of DM/CADM.