RESUMEN
We previously reported that inducing gamma oscillations with a non-invasive light flicker (gamma entrainment using sensory stimulus or GENUS) impacted pathology in the visual cortex of Alzheimer's disease mouse models. Here, we designed auditory tone stimulation that drove gamma frequency neural activity in auditory cortex (AC) and hippocampal CA1. Seven days of auditory GENUS improved spatial and recognition memory and reduced amyloid in AC and hippocampus of 5XFAD mice. Changes in activation responses were evident in microglia, astrocytes, and vasculature. Auditory GENUS also reduced phosphorylated tau in the P301S tauopathy model. Furthermore, combined auditory and visual GENUS, but not either alone, produced microglial-clustering responses, and decreased amyloid in medial prefrontal cortex. Whole brain analysis using SHIELD revealed widespread reduction of amyloid plaques throughout neocortex after multi-sensory GENUS. Thus, GENUS can be achieved through multiple sensory modalities with wide-ranging effects across multiple brain areas to improve cognitive function.
Asunto(s)
Estimulación Acústica/métodos , Enfermedad de Alzheimer/terapia , Cognición/fisiología , Enfermedad de Alzheimer/patología , Amiloide/metabolismo , Péptidos beta-Amiloides/metabolismo , Animales , Percepción Auditiva/fisiología , Encéfalo/metabolismo , Modelos Animales de Enfermedad , Ritmo Gamma/fisiología , Hipocampo/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Microglía/metabolismo , Placa Amiloide/metabolismoRESUMEN
Increased p25, a proteolytic fragment of the regulatory subunit p35, is known to induce aberrant activity of cyclin-dependent kinase 5 (Cdk5), which is associated with neurodegenerative disorders, including Alzheimer's disease. Previously, we showed that replacing endogenous p35 with the noncleavable mutant p35 (Δp35) attenuated amyloidosis and improved cognitive function in a familial Alzheimer's disease mouse model. Here, to address the role of p25/Cdk5 in tauopathy, we generated double-transgenic mice by crossing mice overexpressing mutant human tau (P301S) with Δp35KI mice. We observed significant reduction of phosphorylated tau and its seeding activity in the brain of double transgenic mice compared with the P301S mice. Furthermore, synaptic loss and impaired LTP at hippocampal CA3 region of P301S mice were attenuated by blocking p25 generation. To further validate the role of p25/Cdk5 in tauopathy, we used frontotemporal dementia patient-derived induced pluripotent stem cells (iPSCs) carrying the Tau P301L mutation and generated P301L:Δp35KI isogenic iPSC lines using CRISPR/Cas9 genome editing. We created cerebral organoids from the isogenic iPSCs and found that blockade of p25 generation reduced levels of phosphorylated tau and increased expression of synaptophysin. Together, these data demonstrate a crucial role for p25/Cdk5 in mediating tau-associated pathology and suggest that inhibition of this kinase can remedy neurodegenerative processes in the presence of pathogenic tau mutation.SIGNIFICANCE STATEMENT Accumulation of p25 results in aberrant Cdk5 activation and induction of numerous pathological phenotypes, such as neuroinflammation, synaptic loss, Aß accumulation, and tau hyperphosphorylation. However, it was not clear whether p25/Cdk5 activity is necessary for the progression of these pathological changes. We recently developed the Δp35KI transgenic mouse that is deficient in p25 generation and Cdk5 hyperactivation. In this study, we used this mouse model to elucidate the role of p25/Cdk5 in FTD mutant tau-mediated pathology. We also used a frontotemporal dementia patient-derived induced pluripotent stem cell carrying the Tau P301L mutation and generated isogenic lines in which p35 is replaced with noncleavable mutant Δp35. Our data suggest that p25/Cdk5 plays an important role in tauopathy in both mouse and human model systems.
Asunto(s)
Quinasa 5 Dependiente de la Ciclina/genética , Demencia Frontotemporal/genética , Fosfotransferasas/genética , Células Madre Pluripotentes , Tauopatías/genética , Animales , Región CA3 Hipocampal/patología , Región CA3 Hipocampal/fisiopatología , Quinasa 5 Dependiente de la Ciclina/antagonistas & inhibidores , Demencia Frontotemporal/prevención & control , Humanos , Potenciación a Largo Plazo/genética , Ratones , Ratones Transgénicos , Fibras Musgosas del Hipocampo/patología , Fosforilación , Fosfotransferasas/antagonistas & inhibidores , Trasplante de Células Madre , Sinapsis/patología , Sinaptofisina/genética , Tauopatías/prevención & controlRESUMEN
Antisense oligonucleotides (ASOs) are promising therapeutics for treating various neurological disorders. However, ASOs are unable to readily cross the mammalian blood-brain barrier (BBB) and therefore need to be delivered intrathecally to the central nervous system (CNS). Here, we engineered a human transferrin receptor 1 (TfR1) binding molecule, the oligonucleotide transport vehicle (OTV), to transport a tool ASO across the BBB in human TfR knockin (TfRmu/hu KI) mice and nonhuman primates. Intravenous injection and systemic delivery of OTV to TfRmu/hu KI mice resulted in sustained knockdown of the ASO target RNA, Malat1, across multiple mouse CNS regions and cell types, including endothelial cells, neurons, astrocytes, microglia, and oligodendrocytes. In addition, systemic delivery of OTV enabled Malat1 RNA knockdown in mouse quadriceps and cardiac muscles, which are difficult to target with oligonucleotides alone. Systemically delivered OTV enabled a more uniform ASO biodistribution profile in the CNS of TfRmu/hu KI mice and greater knockdown of Malat1 RNA compared with a bivalent, high-affinity TfR antibody. In cynomolgus macaques, an OTV directed against MALAT1 displayed robust ASO delivery to the primate CNS and enabled more uniform biodistribution and RNA target knockdown compared with intrathecal dosing of the same unconjugated ASO. Our data support systemically delivered OTV as a potential platform for delivering therapeutic ASOs across the BBB.
Asunto(s)
Barrera Hematoencefálica , Oligonucleótidos Antisentido , ARN Largo no Codificante , Receptores de Transferrina , Animales , Oligonucleótidos Antisentido/farmacocinética , Oligonucleótidos Antisentido/administración & dosificación , Barrera Hematoencefálica/metabolismo , Receptores de Transferrina/metabolismo , Humanos , ARN Largo no Codificante/metabolismo , ARN Largo no Codificante/genética , Ratones , Transporte Biológico , Macaca fascicularis , Técnicas de Silenciamiento del Gen , Distribución TisularRESUMEN
Recent increases in human longevity have been accompanied by a rise in the incidence of dementia, highlighting the need to preserve cognitive function in an aging population. A small percentage of individuals with pathological hallmarks of neurodegenerative disease are able to maintain normal cognition. Although the molecular mechanisms that govern this neuroprotection remain unknown, individuals that exhibit cognitive resilience (CgR) represent a unique source of therapeutic insight. For both humans and animal models, living in an enriched, cognitively stimulating environment is the most effective known inducer of CgR. To understand potential drivers of this phenomenon, we began by profiling the molecular changes that arise from environmental enrichment in mice, which led to the identification of MEF2 transcription factors (TFs). We next turned to repositories of human clinical and brain transcriptomic data, where we found that the MEF2 transcriptional network was overrepresented among genes that are most predictive of end-stage cognition. Through single-nucleus RNA sequencing of cortical tissue from resilient and nonresilient individuals, we further confirmed up-regulation of MEF2C in resilient individuals to a subpopulation of excitatory neurons. Last, to determine the causal impact of MEF2 on cognition in the context of neurodegeneration, we overexpressed Mef2a/c in the PS19 mouse model of tauopathy and found that this was sufficient to improve cognitive flexibility and reduce hyperexcitability. Overall, our findings reveal a previously unappreciated role for MEF2 TFs in promoting CgR, highlighting their potential as biomarkers or therapeutic targets for neurodegeneration and healthy aging.
Asunto(s)
Factores de Transcripción MEF2 , Enfermedades Neurodegenerativas , Animales , Encéfalo/metabolismo , Cognición/fisiología , Redes Reguladoras de Genes , Humanos , Factores de Transcripción MEF2/genética , Factores de Transcripción MEF2/metabolismo , Ratones , Enfermedades Neurodegenerativas/genéticaRESUMEN
In this issue of Neuron, Weng et al. (2017) reveal a role for active DNA demethylation in allowing axon regeneration to occur in the mature nervous system following axonal injury.
Asunto(s)
Axones/metabolismo , ADN/metabolismo , Regulación de la Expresión Génica/fisiología , Regeneración Nerviosa/fisiología , Neuronas/metabolismo , Animales , Epigenómica/métodos , HumanosRESUMEN
Prion-like propagation of tau aggregation might underlie the stereotyped progression of neurodegenerative tauopathies. True prions stably maintain unique conformations ("strains") in vivo that link structure to patterns of pathology. We now find that tau meets this criterion. Stably expressed tau repeat domain indefinitely propagates distinct amyloid conformations in a clonal fashion in culture. Reintroduction of tau from these lines into naive cells reestablishes identical clones. We produced two strains in vitro that induce distinct pathologies in vivo as determined by successive inoculations into three generations of transgenic mice. Immunopurified tau from these mice recreates the original strains in culture. We used the cell system to isolate tau strains from 29 patients with 5 different tauopathies, finding that different diseases are associated with different sets of strains. Tau thus demonstrates essential characteristics of a prion. This might explain the phenotypic diversity of tauopathies and could enable more effective diagnosis and therapy.