RESUMEN
Aberrant aggregation of the RNA-binding protein TDP-43 in neurons is a hallmark of frontotemporal lobar degeneration caused by haploinsufficiency in the gene encoding progranulin1,2. However, the mechanism leading to TDP-43 proteinopathy remains unclear. Here we use single-nucleus RNA sequencing to show that progranulin deficiency promotes microglial transition from a homeostatic to a disease-specific state that causes endolysosomal dysfunction and neurodegeneration in mice. These defects persist even when Grn-/- microglia are cultured ex vivo. In addition, single-nucleus RNA sequencing reveals selective loss of excitatory neurons at disease end-stage, which is characterized by prominent nuclear and cytoplasmic TDP-43 granules and nuclear pore defects. Remarkably, conditioned media from Grn-/- microglia are sufficient to promote TDP-43 granule formation, nuclear pore defects and cell death in excitatory neurons via the complement activation pathway. Consistent with these results, deletion of the genes encoding C1qa and C3 mitigates microglial toxicity and rescues TDP-43 proteinopathy and neurodegeneration. These results uncover previously unappreciated contributions of chronic microglial toxicity to TDP-43 proteinopathy during neurodegeneration.
Asunto(s)
Microglía/metabolismo , Microglía/patología , Neuronas/metabolismo , Neuronas/patología , Progranulinas/deficiencia , Proteinopatías TDP-43/metabolismo , Proteinopatías TDP-43/patología , Envejecimiento/genética , Envejecimiento/patología , Animales , Núcleo Celular/genética , Núcleo Celular/patología , Activación de Complemento/efectos de los fármacos , Activación de Complemento/inmunología , Complemento C1q/antagonistas & inhibidores , Complemento C1q/inmunología , Complemento C3b/antagonistas & inhibidores , Complemento C3b/inmunología , Medios de Cultivo Condicionados/química , Medios de Cultivo Condicionados/farmacología , Proteínas de Unión al ADN/metabolismo , Modelos Animales de Enfermedad , Femenino , Masculino , Ratones , Poro Nuclear/metabolismo , Poro Nuclear/patología , Progranulinas/genética , RNA-Seq , Análisis de la Célula Individual , Proteinopatías TDP-43/tratamiento farmacológico , Proteinopatías TDP-43/genética , Tálamo/metabolismo , Tálamo/patología , TranscriptomaRESUMEN
The human cerebral cortex possesses distinct structural and functional features that are not found in the lower species traditionally used to model brain development and disease. Accordingly, considerable attention has been placed on the development of methods to direct pluripotent stem cells to form human brain-like structures termed organoids. However, many organoid differentiation protocols are inefficient and display marked variability in their ability to recapitulate the three-dimensional architecture and course of neurogenesis in the developing human brain. Here, we describe optimized organoid culture methods that efficiently and reliably produce cortical and basal ganglia structures similar to those in the human fetal brain in vivo. Neurons within the organoids are functional and exhibit network-like activities. We further demonstrate the utility of this organoid system for modeling the teratogenic effects of Zika virus on the developing brain and identifying more susceptibility receptors and therapeutic compounds that can mitigate its destructive actions.
Asunto(s)
Antirretrovirales/farmacología , Corteza Cerebral/citología , Evaluación Preclínica de Medicamentos/métodos , Organoides/virología , Cultivo Primario de Células/métodos , Virus Zika/efectos de los fármacos , Línea Celular , Corteza Cerebral/virología , Células Madre Embrionarias/citología , Células Madre Embrionarias/metabolismo , Células Madre Embrionarias/virología , Humanos , Neuronas/citología , Neuronas/metabolismo , Neuronas/virología , Organoides/citología , Organoides/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Factor de Transcripción STAT3/metabolismo , Tirosina Quinasa c-Mer/metabolismoRESUMEN
Microglia maintain homeostasis in the brain, but whether aberrant microglial activation can cause neurodegeneration remains controversial. Here, we use transcriptome profiling to demonstrate that deficiency in frontotemporal dementia (FTD) gene progranulin (Grn) leads to an age-dependent, progressive upregulation of lysosomal and innate immunity genes, increased complement production, and enhanced synaptic pruning in microglia. During aging, Grn(-/-) mice show profound microglia infiltration and preferential elimination of inhibitory synapses in the ventral thalamus, which lead to hyperexcitability in the thalamocortical circuits and obsessive-compulsive disorder (OCD)-like grooming behaviors. Remarkably, deleting C1qa gene significantly reduces synaptic pruning by Grn(-/-) microglia and mitigates neurodegeneration, behavioral phenotypes, and premature mortality in Grn(-/-) mice. Together, our results uncover a previously unrecognized role of progranulin in suppressing aberrant microglia activation during aging. These results represent an important conceptual advance that complement activation and microglia-mediated synaptic pruning are major drivers, rather than consequences, of neurodegeneration caused by progranulin deficiency.
Asunto(s)
Envejecimiento/metabolismo , Encéfalo/metabolismo , Activación de Complemento , Complemento C1q/metabolismo , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Microglía/metabolismo , Envejecimiento/inmunología , Animales , Líquido Cefalorraquídeo , Complemento C1q/genética , Demencia Frontotemporal/genética , Demencia Frontotemporal/metabolismo , Granulinas , Humanos , Inmunidad Innata , Péptidos y Proteínas de Señalización Intercelular/deficiencia , Péptidos y Proteínas de Señalización Intercelular/genética , Lisosomas/metabolismo , Redes y Vías Metabólicas , Ratones , Trastorno Obsesivo Compulsivo/genética , Trastorno Obsesivo Compulsivo/metabolismo , Progranulinas , Sinapsis/metabolismo , Tálamo/metabolismoRESUMEN
Adult-onset autosomal-dominant leukodystrophy (ADLD) is a progressive and fatal neurological disorder characterized by early autonomic dysfunction, cognitive impairment, pyramidal tract and cerebellar dysfunction, and white matter loss in the central nervous system. ADLD is caused by duplication of the LMNB1 gene, which results in increased lamin B1 transcripts and protein expression. How duplication of LMNB1 leads to myelin defects is unknown. To address this question, we developed a mouse model of ADLD that overexpresses lamin B1. These mice exhibited cognitive impairment and epilepsy, followed by age-dependent motor deficits. Selective overexpression of lamin B1 in oligodendrocytes also resulted in marked motor deficits and myelin defects, suggesting these deficits are cell autonomous. Proteomic and genome-wide transcriptome studies indicated that lamin B1 overexpression is associated with downregulation of proteolipid protein, a highly abundant myelin sheath component that was previously linked to another myelin-related disorder, Pelizaeus-Merzbacher disease. Furthermore, we found that lamin B1 overexpression leads to reduced occupancy of Yin Yang 1 transcription factor at the promoter region of proteolipid protein. These studies identify a mechanism by which lamin B1 overexpression mediates oligodendrocyte cell-autonomous neuropathology in ADLD and implicate lamin B1 as an important regulator of myelin formation and maintenance during aging.
Asunto(s)
Lamina Tipo B/metabolismo , Oligodendroglía/patología , Enfermedad de Pelizaeus-Merzbacher/metabolismo , Animales , Axones/metabolismo , Axones/patología , Modelos Animales de Enfermedad , Ataxia de la Marcha/metabolismo , Ataxia de la Marcha/patología , Ataxia de la Marcha/fisiopatología , Predisposición Genética a la Enfermedad , Humanos , Lamina Tipo B/genética , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Actividad Motora , Proteína Proteolipídica de la Mielina/genética , Vaina de Mielina/metabolismo , Vaina de Mielina/patología , Oligodendroglía/metabolismo , Enfermedad de Pelizaeus-Merzbacher/patología , Enfermedad de Pelizaeus-Merzbacher/fisiopatología , Regiones Promotoras Genéticas , Unión Proteica , Prueba de Desempeño de Rotación con Aceleración Constante , Convulsiones/metabolismo , Convulsiones/patología , Convulsiones/fisiopatología , Factor de Transcripción YY1/metabolismoRESUMEN
To understand the role of oxidative stress and mitochondrial defects in the development of neurodegeneration, we examined the age-related pathological changes and corresponding gene expression profiles in homozygous mutant mice deficient in the mitochondrial form of superoxide dismutase (MnSOD, SOD2). These Sod2-/- mice, generated on a B6D2F1 background, developed ataxia at Postnatal Day (P) 11 and progressively deteriorated with frequent seizures by P14. Histopathological examination revealed neurodegenerative changes consistent with the neurological signs. Vacuolar degeneration was observed in neurons and neuropil throughout the brainstem and rostral cortex. The motor trigeminal nucleus in brainstem and the deeper layers of the motor cortex were the earliest regions to degenerate, with the thalamus and hippocampus affected at later stages. Oligonucleotide microarrays were used to compare gene expression profiles in the brainstem and thalamus of Sod2+/+ and -/- mice from birth to P18. Notably, a large set of heat-shock protein genes was transcriptionally down regulated, and this was most likely due to a reduction in the heat-shock transcription factor 1 (HSF1). Other major classes of differentially expressed genes include lipid biosynthesis and ROS metabolism.