RESUMO
Tripartite motif (TRIM) proteins belong to a large family with many roles in host biology, including restricting virus infection. Here, we found that TRIM2, which has been implicated in cases of Charcot-Marie-Tooth disease (CMTD) in humans, acts by blocking hemorrhagic fever New World arenavirus (NWA) entry into cells. We show that Trim2-knockout mice, as well as primary fibroblasts from a CMTD patient with mutations in TRIM2, are more highly infected by the NWAs Junín and Tacaribe virus than wild-type mice or cells are. Using mice with different Trim2 gene deletions and TRIM2 mutant constructs, we demonstrate that its antiviral activity is uniquely independent of the RING domain encoding ubiquitin ligase activity. Finally, we show that one member of the TRIM2 interactome, signal regulatory protein α (SIRPA), a known inhibitor of phagocytosis, also restricts NWA infection and conversely that TRIM2 limits phagocytosis of apoptotic cells. In addition to demonstrating a novel antiviral mechanism for TRIM proteins, these studies suggest that the NWA entry and phagocytosis pathways overlap.
Assuntos
Antígenos de Diferenciação/genética , Arenavirus do Novo Mundo/genética , Doença de Charcot-Marie-Tooth/genética , Interações Hospedeiro-Patógeno/genética , Proteínas Nucleares/genética , Receptores Imunológicos/genética , Animais , Antígenos de Diferenciação/imunologia , Antígenos de Diferenciação/metabolismo , Apoptose , Arenavirus do Novo Mundo/crescimento & desenvolvimento , Arenavirus do Novo Mundo/patogenicidade , Encéfalo/imunologia , Encéfalo/metabolismo , Encéfalo/virologia , Linhagem Celular Tumoral , Doença de Charcot-Marie-Tooth/metabolismo , Doença de Charcot-Marie-Tooth/patologia , Chlorocebus aethiops , Fibroblastos/imunologia , Fibroblastos/metabolismo , Fibroblastos/virologia , Regulação da Expressão Gênica , Células HEK293 , Interações Hospedeiro-Patógeno/imunologia , Humanos , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/virologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 1 Ativada por Mitógeno/imunologia , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/imunologia , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Proteínas de Neurofilamentos/genética , Proteínas de Neurofilamentos/imunologia , Proteínas de Neurofilamentos/metabolismo , Proteínas Nucleares/imunologia , Proteínas Nucleares/metabolismo , Osteoblastos/imunologia , Osteoblastos/metabolismo , Osteoblastos/virologia , Cultura Primária de Células , Receptores Imunológicos/imunologia , Receptores Imunológicos/metabolismo , Transdução de Sinais , Células Vero , Internalização do VírusRESUMO
We analyzed Trim2A/A mice, generated by CRISPR-Cas9, which have a recessive, null mutation of Trim2. Trim2A/A mice develop ataxia that is associated with a severe loss of cerebellar Purkinje cells and a peripheral neuropathy. Myelinated axons in the CNS, including those in the deep cerebellar nuclei, have focal enlargements that contain mitochondria and neurofilaments. In the PNS, there is a loss of myelinated axons, particularly in the most distal nerves. The pathologically affected neuronal populations - primary sensory and motor neurons as well as cerebellar Purkinje cells - express TRIM2, suggesting that loss of TRIM2 in these neurons results in cell autonomous effects on their axons. In contrast, these pathological findings were not found in a second strain of Trim2 mutant mice (Trim2C/C), which has a partial deletion in the RING domain that is needed for ubiquitin ligase activity. Both the Trim2Aand the Trim2C alleles encode mutant TRIM2 proteins with reduced ubiquitination activity. In sum, Trim2A/A mice are a genetically authentic animal model of a recessive axonal neuropathy of humans, apparently for a function that does not depend on the ubiquitin ligase activity.