RESUMO
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.
Assuntos
DNA Helicases , Proteínas de Ligação a Poli-ADP-Ribose , RNA Helicases , Proteínas com Motivo de Reconhecimento de RNA , Transdução de Sinais , Grânulos de Estresse , Proteínas com Motivo Tripartido , Ubiquitina-Proteína Ligases , Ubiquitinação , Humanos , Proteínas de Ligação a Poli-ADP-Ribose/metabolismo , Proteínas de Ligação a Poli-ADP-Ribose/genética , Proteínas com Motivo Tripartido/metabolismo , Proteínas com Motivo Tripartido/genética , Proteínas com Motivo de Reconhecimento de RNA/metabolismo , Proteínas com Motivo de Reconhecimento de RNA/genética , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genética , Grânulos de Estresse/metabolismo , RNA Helicases/metabolismo , DNA Helicases/metabolismo , Proteína DEAD-box 58/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Imunidade Inata , RNA de Cadeia Dupla/metabolismo , Células HEK293 , Células HeLa , Grânulos Citoplasmáticos/metabolismo , Infecções por Vírus de RNA/virologia , Infecções por Vírus de RNA/metabolismo , Infecções por Vírus de RNA/imunologia , Receptores Imunológicos/metabolismoRESUMO
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.