RESUMO
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.
Assuntos
Fibroblastos/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , NF-kappa B/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Fator de Necrose Tumoral alfa/farmacologia , Ubiquitina-Proteína Ligases/metabolismo , Animais , Fibroblastos/enzimologia , Células HEK293 , Humanos , Quinase I-kappa B/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Macrófagos/enzimologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Complexos Multienzimáticos , Fosforilação , Proteínas Serina-Treonina Quinases/deficiência , Proteínas Serina-Treonina Quinases/genética , Receptores Tipo I de Fatores de Necrose Tumoral/genética , Receptores Tipo I de Fatores de Necrose Tumoral/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fator 2 Associado a Receptor de TNF/genética , Fator 2 Associado a Receptor de TNF/metabolismo , Ubiquitina-Proteína Ligases/genética , UbiquitinaçãoRESUMO
Linear ubiquitin chain assembly complex (LUBAC) is a ubiquitin E3 ligase complex composed of HOIP, HOIL-1L, and SHARPIN that catalyzes the formation of linear/M1- linked ubiquitin chain. It has been shown to play a pivotal role in the nuclear factor (NF)-κB signaling induced by proinflammatory stimuli. Here, we found that tumor susceptibility gene (TSG101) physically interacts with HOIP, a catalytic component of LUBAC, and potentiates LUBAC activity. Depletion of TSG101 expression by RNA interference decreased TNFα-induced linear ubiquitination and the formation of TNFα receptor 1 signaling complex (TNFRSC). Furthermore, TSG101 facilitated the TNFα-induced stimulation of the NF-κB pathway. Thus, we suggest that TSG101 functions as a positive modulator of HOIP that mediates TNFα-induced NF-κB signaling pathway.