RESUMEN
Stress granules (SGs) are induced by various environmental stressors, resulting in their compositional and functional heterogeneity. SGs play a crucial role in the antiviral process, owing to their potent translational repressive effects and ability to trigger signal transduction; however, it is poorly understood how these antiviral SGs differ from SGs induced by other environmental stressors. Here we identify that TRIM25, a known driver of the ubiquitination-dependent antiviral innate immune response, is a potent and critical marker of the antiviral SGs. TRIM25 undergoes liquid-liquid phase separation (LLPS) and co-condenses with the SG core protein G3BP1 in a dsRNA-dependent manner. The co-condensation of TRIM25 and G3BP1 results in a significant enhancement of TRIM25's ubiquitination activity towards multiple antiviral proteins, which are mainly located in SGs. This co-condensation is critical in activating the RIG-I signaling pathway, thus restraining RNA virus infection. Our studies provide a conceptual framework for better understanding the heterogeneity of stress granule components and their response to distinct environmental stressors.
Asunto(s)
ADN Helicasas , Proteínas de Unión a Poli-ADP-Ribosa , ARN Helicasas , Proteínas con Motivos de Reconocimiento de ARN , Transducción de Señal , Gránulos de Estrés , Proteínas de Motivos Tripartitos , Ubiquitina-Proteína Ligasas , Ubiquitinación , Humanos , Proteínas de Unión a Poli-ADP-Ribosa/metabolismo , Proteínas de Unión a Poli-ADP-Ribosa/genética , Proteínas de Motivos Tripartitos/metabolismo , Proteínas de Motivos Tripartitos/genética , Proteínas con Motivos de Reconocimiento de ARN/metabolismo , Proteínas con Motivos de Reconocimiento de ARN/genética , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitina-Proteína Ligasas/genética , Gránulos de Estrés/metabolismo , ARN Helicasas/metabolismo , ADN Helicasas/metabolismo , Proteína 58 DEAD Box/metabolismo , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Inmunidad Innata , ARN Bicatenario/metabolismo , Células HEK293 , Células HeLa , Gránulos Citoplasmáticos/metabolismo , Infecciones por Virus ARN/virología , Infecciones por Virus ARN/metabolismo , Infecciones por Virus ARN/inmunología , Receptores Inmunológicos/metabolismoRESUMEN
Autophagy can selectively target protein aggregates, pathogens, and dysfunctional organelles for the lysosomal degradation. Aberrant regulation of autophagy promotes tumorigenesis, while it is far less clear whether and how tumor-specific alterations result in autophagic aberrance. To form a link between aberrant autophagy selectivity and human cancer, we establish a computational pipeline and prioritize 222 potential LIR (LC3-interacting region) motif-associated mutations (LAMs) in 148 proteins. We validate LAMs in multiple proteins including ATG4B, STBD1, EHMT2 and BRAF that impair their interactions with LC3 and autophagy activities. Using a combination of transcriptomic, metabolomic and additional experimental assays, we show that STBD1, a poorly-characterized protein, inhibits tumor growth via modulating glycogen autophagy, while a patient-derived W203C mutation on LIR abolishes its cancer inhibitory function. This work suggests that altered autophagy selectivity is a frequently-used mechanism by cancer cells to survive during various stresses, and provides a framework to discover additional autophagy-related pathways that influence carcinogenesis.