RESUMEN
The nuclear factor (NF)-κB pathway plays a central role in inflammatory and immune responses, with aberrant activation of NF-κB signaling being implicated in various human disorders. Here, we show that mammalian ste20-like kinase 1 (MST1) is a previously unrecognized component of the tumor necrosis factor α (TNFα) receptor 1 signaling complex (TNF-RSC) and attenuates TNFα-induced NF-κB signaling. Genetic ablation of MST1 in mouse embryonic fibroblasts and bone marrow-derived macrophages potentiated the TNFα-induced increase in IκB kinase (IKK) activity, as well as the expression of NF-κB target genes. TNFα induced the recruitment of MST1 to TNF-RSC and its interaction with HOIP, the catalytic component of the E3 ligase linear ubiquitin assembly complex (LUBAC). Furthermore, MST1 activated in response to TNFα stimulation mediates the phosphorylation of HOIP and thereby inhibited LUBAC-dependent linear ubiquitination of NEMO/IKKγ. Together, our findings suggest that MST1 negatively regulates TNFα-induced NF-κB signaling by targeting LUBAC.
Asunto(s)
Fibroblastos/efectos de los fármacos , Macrófagos/efectos de los fármacos , FN-kappa B/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Factor de Necrosis Tumoral alfa/farmacología , Ubiquitina-Proteína Ligasas/metabolismo , Animales , Fibroblastos/enzimología , Células HEK293 , Humanos , Quinasa I-kappa B/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Macrófagos/enzimología , Ratones Endogámicos C57BL , Ratones Noqueados , Complejos Multienzimáticos , Fosforilación , Proteínas Serina-Treonina Quinasas/deficiencia , Proteínas Serina-Treonina Quinasas/genética , Receptores Tipo I de Factores de Necrosis Tumoral/genética , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Transducción de Señal/efectos de los fármacos , Factor 2 Asociado a Receptor de TNF/genética , Factor 2 Asociado a Receptor de TNF/metabolismo , Ubiquitina-Proteína Ligasas/genética , UbiquitinaciónRESUMEN
Excessive activation of the ionotropic N-methyl-D-aspartate (NMDA) receptor has been shown to cause abnormally high levels of Ca2+ influx, thereby leading to excitotoxic neuronal death. In this study, exposure of mouse primary cortical neurons to NMDA resulted in the cleavage and activation of mammalian sterile 20-like kinase-1 (MST1), both of which were mediated by calpain 1. In vitro cleavage assay data indicated that calpain 1 cleaves out the autoinhibitory domain of MST1 to generate an active form of the kinase. Furthermore, calpain 1 mediated the cleavage and activation of wild-type MST1, but not of MST1 (G339A). Intriguingly, NMDA/calpain-induced MST1 activation promoted the nuclear translocation of the kinase and the phosphorylation of histone H2B in mouse cortical neurons, leading to excitotoxicity. Thus, we propose a previously unrecognized mechanism of MST1 activation associated with NMDA-induced excitotoxic neuronal death.