RESUMO
Pathogenic variants in valosin-containing protein (VCP) cause multisystem proteinopathy (MSP), a disease characterized by multiple clinical phenotypes including inclusion body myopathy, Paget's disease of the bone, and frontotemporal dementia (FTD). How such diverse phenotypes are driven by pathogenic VCP variants is not known. We found that these diseases exhibit a common pathologic feature: ubiquitinated intranuclear inclusions affecting myocytes, osteoclasts, and neurons. Moreover, knock-in cell lines harboring MSP variants show a reduction in nuclear VCP. Given that MSP is associated with neuronal intranuclear inclusions comprised of TDP-43 protein, we developed a cellular model whereby proteostatic stress results in the formation of insoluble intranuclear TDP-43 aggregates. Consistent with a loss of nuclear VCP function, cells harboring MSP variants or cells treated with VCP inhibitor exhibited decreased clearance of insoluble intranuclear TDP-43 aggregates. Moreover, we identified 4 compounds that activate VCP primarily by increasing D2 ATPase activity, where pharmacologic VCP activation appears to enhance clearance of insoluble intranuclear TDP-43 aggregate. Our findings suggest that VCP function is important for nuclear protein homeostasis, that impaired nuclear proteostasis may contribute to MSP, and that VCP activation may be a potential therapeutic by virtue of enhancing the clearance of intranuclear protein aggregates.
Assuntos
Proteínas de Ligação a DNA , Demência Frontotemporal , Miosite de Corpos de Inclusão , Proteostase , Proteína com Valosina , Proteína com Valosina/metabolismo , Proteína com Valosina/genética , Humanos , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/genética , Demência Frontotemporal/patologia , Demência Frontotemporal/genética , Demência Frontotemporal/metabolismo , Demência Frontotemporal/tratamento farmacológico , Miosite de Corpos de Inclusão/metabolismo , Miosite de Corpos de Inclusão/patologia , Miosite de Corpos de Inclusão/genética , Miosite de Corpos de Inclusão/tratamento farmacológico , Osteíte Deformante/metabolismo , Osteíte Deformante/genética , Osteíte Deformante/patologia , Osteíte Deformante/tratamento farmacológico , Agregados Proteicos/efeitos dos fármacos , Núcleo Celular/metabolismo , Proteinopatias TDP-43/metabolismo , Proteinopatias TDP-43/patologia , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/tratamento farmacológico , Animais , Camundongos , Corpos de Inclusão Intranuclear/metabolismo , Corpos de Inclusão Intranuclear/patologia , Corpos de Inclusão Intranuclear/genéticaRESUMO
Pathogenic variants in VCP cause multisystem proteinopathy (MSP), a disease characterized by multiple clinical phenotypes including inclusion body myopathy, Paget's disease of the bone, and frontotemporal dementia (FTD). How such diverse phenotypes are driven by pathogenic VCP variants is not known. We found that these diseases exhibit a common pathologic feature, ubiquitinated intranuclear inclusions affecting myocytes, osteoclasts and neurons. Moreover, knock-in cell lines harboring MSP variants show a reduction in nuclear VCP. Given that MSP is associated with neuronal intranuclear inclusions comprised of TDP-43 protein, we developed a cellular model whereby proteostatic stress results in the formation of insoluble intranuclear TDP-43 aggregates. Consistent with a loss of nuclear VCP function, cells harboring MSP variants or cells treated with VCP inhibitor exhibited decreased clearance of insoluble intranuclear TDP-43 aggregates. Moreover, we identified four novel compounds that activate VCP primarily by increasing D2 ATPase activity whereby pharmacologic VCP activation appears to enhance clearance of insoluble intranuclear TDP-43 aggregate. Our findings suggest that VCP function is important for nuclear protein homeostasis, that MSP may be the result of impaired nuclear proteostasis, and that VCP activation may be potential therapeutic by virtue of enhancing the clearance of intranuclear protein aggregates.
