RESUMEN
Neuroinflammation is causally associated with Alzheimer's disease (AD) pathology. Reactive glia cells secrete various neurotoxic factors that impair neuronal homeostasis eventually leading to neuronal loss. Although the glial activation mechanism in AD has been relatively well studied, how it perturbs intraneuronal signaling, which ultimately leads to neuronal cell death, remains poorly understood. Here, we report that compound stimulation with the neurotoxic factors TNF and glutamate aberrantly activates neuronal TAK1 (also known as MAP3K7), which promotes the pathogenesis of AD in mouse models. Glutamate-induced Ca2+ influx shifts TNF signaling to hyper-activate TAK1 enzymatic activity through Ca2+/calmodulin-dependent protein kinase II, which leads to necroptotic cellular damage. Genetic ablation and pharmacological inhibition of TAK1 ameliorated AD-associated neuronal loss and cognitive impairment in the AD model mice. Our findings provide a molecular mechanism linking cytokines, Ca2+ signaling and neuronal necroptosis in AD.
Asunto(s)
Enfermedad de Alzheimer , Animales , Ratones , Enfermedad de Alzheimer/genética , Calcio , Citocinas/metabolismo , Enfermedades Neuroinflamatorias , Transducción de Señal/fisiologíaRESUMEN
The posttranslational regulation of the neuronal proteome is critical for brain homeostasis but becomes dysregulated in the aged or diseased brain, in which abnormal posttranslational modifications (PTMs) are frequently observed. While the full extent of modified substrates that comprise the "PTM-ome" are slowly emerging, how the upstream enzymes catalyzing these processes are regulated themselves is not well understood, particularly in the context of neurodegeneration. Here, we describe the reciprocal regulation of a kinase, the microtubule affinity-regulating kinase 2 (MARK2), and an acetyltransferase, CREB-binding protein (CBP), two enzymes known to extensively modify tau proteins in the progression of Alzheimer's disease. We found that MARK2 negatively regulates CBP and, conversely, CBP directly acetylates and inhibits MARK2 kinase activity. These findings highlight a reciprocal negative feedback loop between a kinase and an acetyltransferase, which has implications for how PTM interplay is coordinated on substrates including tau. Our study suggests that PTM profiles occur through the posttranslational control of the master PTM remodeling enzymes themselves.
Asunto(s)
Proteína de Unión a CREB/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Acetiltransferasas/metabolismo , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Animales , Retroalimentación , Humanos , Ratones , Microtúbulos/metabolismo , Fosforilación , Procesamiento Proteico-Postraduccional , Proteínas tau/genética , Proteínas tau/metabolismoRESUMEN
BACKGROUND: Alzheimer's disease (AD) is characterized by a progressive loss of memory that cannot be efficiently managed by currently available AD therapeutics. So far, most treatments for AD that have the potential to improve memory target neural circuits to protect their integrity. However, the vulnerable neural circuits and their dynamic remodeling during AD progression remain largely undefined. METHODS: Circuit-based approaches, including anterograde and retrograde tracing, slice electrophysiology, and fiber photometry, were used to investigate the dynamic structural and functional remodeling of a GABAergic circuit projected from the medial septum (MS) to the dentate gyrus (DG) in 3xTg-AD mice during AD progression. RESULTS: We identified a long-distance GABAergic circuit that couples highly connected MS and DG GABAergic neurons during spatial memory encoding. Furthermore, we found hyperactivity of DG interneurons during early AD, which persisted into late AD stages. Interestingly, MS GABAergic projections developed a series of adaptive strategies to combat DG interneuron hyperactivity. During early-stage AD, MS-DG GABAergic projections exhibit increased inhibitory synaptic strength onto DG interneurons to inhibit their activities. During late-stage AD, MS-DG GABAergic projections form higher anatomical connectivity with DG interneurons and exhibit aberrant outgrowth to increase the inhibition onto DG interneurons. CONCLUSION: We report the structural and functional remodeling of the MS-DG GABAergic circuit during disease progression in 3xTg-AD mice. Dynamic MS-DG GABAergic circuit remodeling represents a compensatory mechanism to combat DG interneuron hyperactivity induced by reduced GABA transmission.
Asunto(s)
Enfermedad de Alzheimer , Ratones , Animales , Ratones Transgénicos , HipocampoRESUMEN
ABSTRACT: Binge drinking is a risk factor for cardiac arrhythmias, known as the holiday heart syndrome. Atrial fibrillation (AF) is the most frequently diagnosed arrhythmia in this condition. Recent reports indicated that cardiac ryanodine receptor (RyR2) dysfunction and Ca 2+ leak contribute to alcohol-enhanced AF. In this study, we investigated whether stabilizing RyR2 with dantrolene treatment can prevent alcohol-enhanced AF in rats. A binge drinking rat model was established with alcohol (2 g /kg, IP) delivered once every other day for 4 times. The study consisted of following 3 groups: control group (n = 9), binge alcohol group (n = 10), and binge alcohol + dantrolene (A+D) group (dantrolene, 10 mg/kg, IP before each alcohol injection, n = 9). Echocardiography, left ventricular hemodynamics, in vivo atrial electrophysiology and AF inducibility test, RyR2 phosphorylation level, and blood norepinephrine level were studied 24 hours after the last injection. Ca 2+ leak in isolated atrial myocytes from control and binge alcohol rats was examined. Binge alcohol significantly increased AF inducibility (1/9 in control vs. 8/9 in binge alcohol group, P < 0.05) and AF duration. Dantrolene treatment significantly reduced both AF inducibility (2/9 in dantrolene group, P < 0.05) and AF duration. Binge alcohol significantly increased Ca 2+ leak in isolated atrial myocytes, which was reduced by dantrolene treatment. Blood norepinephrine,7 RyR2 phosphorylation level, cardiac echocardiography, and left ventricular hemodynamics were not significantly affected 24 hours after binge drinking. In conclusion, stabilizing RyR2 with dantrolene treatment significantly attenuated binge drinking-enhanced AF, suggesting that therapeutic strategies stabilizing RyR2 could be a preventive measure to blunt binge drinking-enhanced AF arrhythmogenesis.
Asunto(s)
Fibrilación Atrial , Consumo Excesivo de Bebidas Alcohólicas , Ratas , Animales , Dantroleno/farmacología , Canal Liberador de Calcio Receptor de Rianodina , Fibrilación Atrial/tratamiento farmacológico , Fibrilación Atrial/etiología , Fibrilación Atrial/prevención & control , Consumo Excesivo de Bebidas Alcohólicas/complicaciones , Atrios Cardíacos/metabolismo , Miocitos Cardíacos/metabolismo , Etanol , Norepinefrina , Calcio/metabolismo , Retículo Sarcoplasmático/metabolismoRESUMEN
TAR DNA-binding protein 43 (TDP-43) is a nucleic acid-binding protein, and its aggregation represents the defining pathology in amyotrophic lateral sclerosis (ALS) and related proteinopathies. Recent studies implicate cytoplasmic stress granules (SGs) as hubs that may facilitate TDP-43 aggregation. Here, using cellular fractionation, biochemical analyses, and histological assays, we show that TDP-43 targeted to the cytoplasm has multiple fates. Whereas a TDP-43 subpopulation is indeed recruited to SGs, mature aggregated TDP-43, produced with aggregate-prone TDP-43 variants or exposure to oxidative stress, generates distinct TDP-43 inclusions that are surprisingly devoid of SGs. Consistent with this observation, we found that SG components are predominantly excluded from TDP-43 pathology in motor neurons from individuals with ALS. We generated de novo SGs by expressing the fragile X protein (FMRP) and found that rather than directly engaging TDP-43 aggregates, SGs can sequester the proteostasis factor histone deacetylase 6 (HDAC6) and thereby impede TDP-43 clearance from cells. These findings indicate that SGs form distinct cytoplasmic structures that can indirectly enhance TDP-43 aggregation. Therapeutic approaches that inhibit SG formation may therefore be effective at suppressing TDP-43-mediated toxicity in patients with ALS and related TDP-43 proteinopathies.
Asunto(s)
Citosol/metabolismo , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/metabolismo , Agregado de Proteínas , Esclerosis Amiotrófica Lateral/metabolismo , Esclerosis Amiotrófica Lateral/patología , Animales , Línea Celular , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/metabolismo , Conformación Proteica , Transporte de Proteínas , Médula Espinal/patologíaRESUMEN
Abnormal intracellular accumulation of aggregated tau is a hallmark feature of Alzheimer's disease and other tauopathies. Pathological tau can undergo a range of post-translational modifications (PTMs) that are implicated as triggers of disease pathology. Recent studies now indicate that tau acetylation, in particular, controls both microtubule binding and tau aggregation, thereby acting as a central regulator of tau's biochemical properties and providing avenues to exploit for potential therapies. Here, using cell-based assays and tau transgenic mice harboring an acetylation-mimic mutation at residue Lys-280 (K280Q), we evaluated whether this substitution modifies the neurodegenerative disease pathology associated with the aggregate-prone tau P301S variant. Strikingly, the addition of a K280Q-substituted variant altered P301S-mediated tau conformation and reduced tau hyperphosphorylation. We further evaluated neurodegeneration markers in K280Q acetylation-mimic mice and observed reduced neuroinflammation as well as restored levels of N-methyl-d-aspartate receptors and post-synaptic markers compared with the parental mice. Thus, substituting a single lysine residue in the context of a P301S disease-linked mutation produces a unique tau species that abrogates some of the cardinal features of tauopathy. The findings of our study indicate that a complex tau PTM code likely regulates tau pathogenesis, highlighting the potential utility of manipulating and detoxifying tau strains through site-specific tau-targeting approaches.
Asunto(s)
Tauopatías/patología , Proteínas tau/metabolismo , Acetilación , Animales , Corteza Cerebral/metabolismo , Corteza Cerebral/patología , Hipocampo/metabolismo , Hipocampo/patología , Estimación de Kaplan-Meier , Lisina/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mutagénesis Sitio-Dirigida , Fosforilación , Receptores de N-Metil-D-Aspartato/metabolismo , Tauopatías/metabolismo , Tauopatías/mortalidad , Proteínas tau/genéticaRESUMEN
Prolonged deficits in neural input activate pathological muscle remodeling, leading to atrophy. In denervated muscle, activation of the atrophy program requires HDAC4, a potent repressor of the master muscle transcription factor MEF2. However, the signaling mechanism that connects HDAC4, a protein deacetylase, to the atrophy machinery remains unknown. Here, we identify the AP1 transcription factor as a critical target of HDAC4 in neurogenic muscle atrophy. In denervated muscle, HDAC4 activates AP1-dependent transcription, whereas AP1 inactivation recapitulates HDAC4 deficiency and blunts the muscle atrophy program. We show that HDAC4 activates AP1 independently of its canonical transcriptional repressor activity. Surprisingly, HDAC4 stimulates AP1 activity by activating the MAP kinase cascade. We present evidence that HDAC4 binds and promotes the deacetylation and activation of a key MAP3 kinase, MEKK2. Our findings establish an HDAC4-MAPK-AP1 signaling axis essential for neurogenic muscle atrophy and uncover a direct crosstalk between acetylation- and phosphorylation-dependent signaling cascades.
Asunto(s)
Histona Desacetilasas/metabolismo , MAP Quinasa Quinasa Quinasa 2/metabolismo , Músculo Esquelético/metabolismo , Factor de Transcripción AP-1/metabolismo , Acetilación , Animales , Western Blotting , Línea Celular , Células HEK293 , Histona Desacetilasas/genética , Humanos , MAP Quinasa Quinasa Quinasa 2/genética , Sistema de Señalización de MAP Quinasas , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Datos de Secuencia Molecular , Desnervación Muscular , Músculo Esquelético/inervación , Atrofia Muscular/genética , Atrofia Muscular/metabolismo , Fosforilación , Unión Proteica , Interferencia de ARN , Factor de Transcripción AP-1/genéticaRESUMEN
TDP-43 is the major disease protein in ubiquitin-positive inclusions of amyotrophic lateral sclerosis and frontotemporal lobar degeneration (FTLD) characterized by TDP-43 pathology (FTLD-TDP). Accumulation of insoluble TDP-43 aggregates could impair normal TDP-43 functions and initiate disease progression. Thus, it is critical to define the signalling mechanisms regulating TDP-43 since this could open up new avenues for therapeutic interventions. Here, we have identified a redox-mediated signalling mechanism directly regulating TDP-43. Using in vitro and cell-based studies, we demonstrate that oxidative stress promotes TDP-43 cross-linking via cysteine oxidation and disulphide bond formation leading to decreased TDP-43 solubility. Biochemical analysis identified several cysteine residues located within and adjacent to the second RNA-recognition motif that contribute to both intra- and inter-molecular interactions, supporting TDP-43 as a target of redox signalling. Moreover, increased levels of cross-linked TDP-43 species are found in FTLD-TDP brains, indicating that aberrant TDP-43 cross-linking is a prominent pathological feature of this disease. Thus, TDP-43 is dynamically regulated by a redox regulatory switch that links oxidative stress to the modulation of TDP-43 and its downstream targets.
Asunto(s)
Cisteína/metabolismo , Proteínas de Unión al ADN/metabolismo , Disulfuros/metabolismo , Estrés Oxidativo , Transducción de Señal , Secuencia de Aminoácidos , Encéfalo/patología , Línea Celular , Degeneración Lobar Frontotemporal/patología , Humanos , Datos de Secuencia Molecular , Oxidación-ReducciónRESUMEN
We have recently shown acetylation of tau at lysine residue 280 (AC-K280) to be a disease-specific modification in Alzheimer disease (AD), corticobasal degeneration, and progressive supranuclear palsy, likely representing a major regulatory tau modification. Herein, we extend our observations using IHC with a polyclonal antibody specific for AC-K280. Thirty brain regions were examined in argyrophilic grain disease (AGD; n = 5), tangle-predominant senile dementia (TPSD; n = 5), Pick disease (n = 4), familial AD (FAD; n = 2; PSEN1 p.G206A and p.S170P), and frontotemporal dementia with parkinsonism linked to chromosome-17 (FTDP-17; n = 2; MAPT p.P301L and IVS10 + 16). All AGD, TPSD, FAD, and FTDP-17 cases had significant AC-K280 reactivity that was similar in severity and distribution to phosphorylated tau. AC-K280 robustly labeled grain pathological characteristics in AGD and was predominantly associated with thioflavin-S-positive neurofibrillary tangles and less reactive in neuropil threads and extracellular tangles in TPSD and FAD. Thioflavin-S-negative neuronal and glial inclusions of patients with FTDP-17 were robustly AC-K280 reactive. A low degree of AC-K280 was found in a subset of 4-repeat tau-containing lesions in Pick disease. AC-K280 is a prominent feature of both neuronal and glial tau aggregations in tauopathies of various etiologies. The close association of AC-K280 with amyloid and pre-amyloid conformations of tau suggests a potential role in tangle maturation and, thus, could serve as a useful biomarker or therapeutic target in a variety of tauopathies.
Asunto(s)
Encéfalo/metabolismo , Lisina/metabolismo , Tauopatías/diagnóstico , Proteínas tau/metabolismo , Acetilación , Biomarcadores/metabolismo , Humanos , Inmunohistoquímica , Tauopatías/genética , Tauopatías/metabolismoRESUMEN
CONTEXT: Osteopathic manipulative treatment (OMT) has been demonstrated to have an effect on the autonomic nervous system, which may have antiarrhythmic effects. The effects of OMT in patients with cardiac implantable electronic devices (CIEDs) have not previously been reported. This study investigated the impact of OMT on quality of life (QOL) in this patient population. OBJECTIVES: The purpose of this study is to investigate the effects of OMT on QOL in CIED patients. METHODS: Subjects with CIEDs were recruited into a double-blind randomized controlled institutional review board (IRB)-approved clinical trial (ClinicalTrials.gov ID: NCT04004741) and randomized to OMT or light touch (control) groups. Subjects received a one-time intervention, performed by board-certified neuromusculoskeletal medicine (NMM) and osteopathic manipulative medicine (OMM) physicians. The OMT protocol utilized techniques including myofascial release, rib raising, facilitated positional release (FPR), and osteopathic cranial manipulative medicine. Subjects' QOL was assessed immediately preceding intervention and one-month postintervention utilizing the Research ANd Development (RAND) 36-Item Short Form Health Survey (SF-36, eight parameters). Groups were compared utilizing unpaired t tests; α=0.05. RESULTS: Forty-two subjects were enrolled, with four lost to follow-up, which resulted in 19 OMT and 19 control subjects for analysis. Of the eight QOL parameters, two showed significant improvement with OMT: role limitations due to physical health (p=0.001) and pain (p=0.003). CONCLUSIONS: This study demonstrates the potential for QOL improvement in CIED patients. Specifically, subjects in the OMT group reported an improvement in activities of daily living as well as a decrease in overall pain, including pain interfering with work. Additional research is necessary to further understand the physiologic effects of OMT, including its effects on arrhythmias, in CIED patients.
Asunto(s)
Desfibriladores Implantables , Osteopatía , Marcapaso Artificial , Calidad de Vida , Humanos , Osteopatía/métodos , Femenino , Masculino , Método Doble Ciego , Persona de Mediana Edad , Anciano , Adulto , Resultado del TratamientoRESUMEN
Sleep disruption and impaired synaptic processes are common features in neurodegenerative diseases, including Alzheimer's disease (AD). Hyperphosphorylated Tau is known to accumulate at neuronal synapses in AD, contributing to synapse dysfunction. However, it remains unclear how sleep disruption and synapse pathology interact to contribute to cognitive decline. Here, we examined sex-specific onset and consequences of sleep loss in AD/tauopathy model PS19 mice. Using a piezoelectric home-cage monitoring system, we showed PS19 mice exhibited early-onset and progressive hyperarousal, a selective dark-phase sleep disruption, apparent at 3 months in females and 6 months in males. Using the Morris water maze test, we report that chronic sleep disruption (CSD) accelerated the onset of decline of hippocampal spatial memory in PS19 males only. Hyperarousal occurs well in advance of robust forebrain synaptic Tau burden that becomes apparent at 6-9 months. To determine whether a causal link exists between sleep disruption and synaptic Tau hyperphosphorylation, we examined the correlation between sleep behavior and synaptic Tau, or exposed mice to acute or chronic sleep disruption at 6 months. While we confirm that sleep disruption is a driver of Tau hyperphosphorylation in neurons of the locus ceruleus, we were unable to show any causal link between sleep loss and Tau burden in forebrain synapses. Despite the finding that hyperarousal appears earlier in females, female cognition was resilient to the effects of sleep disruption. We conclude sleep disruption interacts with the synaptic Tau burden to accelerate the onset of cognitive decline with greater vulnerability in males.
Asunto(s)
Disfunción Cognitiva , Modelos Animales de Enfermedad , Ratones Transgénicos , Prosencéfalo , Sinapsis , Proteínas tau , Animales , Proteínas tau/metabolismo , Masculino , Femenino , Disfunción Cognitiva/metabolismo , Disfunción Cognitiva/etiología , Sinapsis/metabolismo , Sinapsis/patología , Ratones , Prosencéfalo/metabolismo , Caracteres Sexuales , Tauopatías/metabolismo , Tauopatías/patología , Trastornos del Sueño-Vigilia/metabolismo , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Ratones Endogámicos C57BLRESUMEN
Sleep disruption is an expected component of aging and neurodegenerative conditions, including Alzheimer's disease (AD). Sleep disruption has been demonstrated as a driver of AD pathology and cognitive decline. Therefore, treatments designed to maintain sleep may be effective in slowing or halting AD progression. However, commonly used sleep aid medications are associated with an increased risk of AD, highlighting the need for sleep aids with novel mechanisms of action. The endocannabinoid system holds promise as a potentially effective and novel sleep-enhancing target. By using pharmacology and genetic knockout strategies, we evaluated fatty acid amide hydrolase (FAAH) as a therapeutic target to improve sleep and halt disease progression in a transgenic Tau P301S (PS19) model of Tauopathy and AD. We have recently shown that PS19 mice exhibit sleep disruption in the form of dark phase hyperarousal as an early symptom that precedes robust Tau pathology and cognitive decline. Acute FAAH inhibition with PF3845 resulted in immediate improvements in sleep behaviors in male and female PS19 mice, supporting FAAH as a potentially suitable sleep-promoting target. Moreover, sustained drug dosing for 5-10 days resulted in maintained improvements in sleep. To evaluate the effect of chronic FAAH inhibition as a possible therapeutic strategy, we generated FAAH-/- PS19 mice models. Counter to our expectations, FAAH knockout did not protect PS19 mice from progressive sleep loss, neuroinflammation, or cognitive decline. Our results provide support for FAAH as a novel target for sleep-promoting therapies but further indicate that the complete loss of FAAH activity may be detrimental.
RESUMEN
Amyotrophic lateral sclerosis is the most common fatal motor neuron disease. Approximately 90% of ALS patients exhibit pathology of the master RNA regulator, Transactive Response DNA Binding protein (TDP-43). Despite the prevalence TDP-43 pathology in ALS motor neurons, recent findings suggest immune dysfunction is a determinant of disease progression in patients. Whether TDP-43 pathology elicits disease-modifying immune responses in ALS remains underexplored. In this study, we demonstrate that TDP-43 pathology is internalized by antigen presenting cells, causes vesicle rupture, and leads to innate and adaptive immune cell activation. Using a multiplex imaging platform, we observed interactions between innate and adaptive immune cells near TDP-43 pathological lesions in ALS brain. We used a mass cytometry-based whole-blood stimulation assay to provide evidence that ALS patient peripheral immune cells exhibit responses to TDP-43 aggregates. Taken together, this study provides a novel link between TDP-43 pathology and ALS immune dysfunction, and further highlights the translational and diagnostic implications of monitoring and manipulating the ALS immune response.
RESUMEN
The microtubule-binding protein, tau, is the major component of neurofibrillary inclusions characteristic of Alzheimer's disease and related neurodegenerative tauopathies. When tau fibrillizes, it undergoes abnormal post-translational modifications resulting in decreased solubility and altered microtubule-stabilizing properties. Recently, we reported that the abnormal acetylation of tau at lysine residue 280 is a novel, pathological post-translational modification. Here, we performed detailed immunohistochemistry to further examine acetylated-tau expression in Alzheimer's disease and other major tauopathies. Immunohistochemistry using a polyclonal antibody specific for acetylated-tau at lysine 280 was conducted on 30 post-mortem central nervous system regions from patients with Alzheimer's disease (10 patients), corticobasal degeneration (5 patients), and progressive supranuclear palsy (5 patients). Acetylated-tau pathology was compared with the sequential emergence of other tau modifications in the Alzheimer's disease hippocampus using monoclonal antibodies to multiple well-characterized tau epitopes. All cases studied showed significant acetylated-tau pathology in a distribution pattern similar to hyperphosphorylated-tau. Acetylated-tau pathology was largely in intracellular, thioflavin-S-positive tau inclusions in Alzheimer's disease, and also thioflavin-S-negative pathology in corticobasal degeneration and progressive supranuclear palsy. Acetylated-tau was present throughout all stages of Alzheimer's disease pathology, but was more prominently associated with pathological tau epitopes in moderate to severe-stage cases. These temporal and morphological immunohistochemical features suggest acetylation of tau at this epitope is preceded by early modifications, including phosphorylation, and followed by later truncation events and cell death in Alzheimer's disease. Acetylation of tau at lysine 280 is a pathological modification that may contribute to tau-mediated neurodegeneration by both augmenting losses of normal tau properties (reduced solubility and microtubule assembly) as well as toxic gains of function (increased tau fibrillization). Thus, inhibiting tau acetylation could be a disease-modifying target for drug discovery target in tauopathies.
Asunto(s)
Enfermedad de Alzheimer/genética , Tauopatías/genética , Proteínas tau/genética , Acetilación , Anciano , Ganglios Basales/patología , Corteza Cerebral/patología , Progresión de la Enfermedad , Epítopos , Femenino , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Degeneración Nerviosa/patología , Ovillos Neurofibrilares/patología , Fosforilación , Deficiencias en la Proteostasis/patología , Parálisis Supranuclear Progresiva/patología , Bancos de Tejidos , Proteínas tau/inmunologíaRESUMEN
Background: Sleep is an essential process that supports brain health and cognitive function in part through the modification of neuronal synapses. Sleep disruption, and impaired synaptic processes, are common features in neurodegenerative diseases, including Alzheimer's disease (AD). However, the casual role of sleep disruption in disease progression is not clear. Neurofibrillary tangles, made from hyperphosphorylated and aggregated Tau protein, form one of the major hallmark pathologies seen in AD and contribute to cognitive decline, synapse loss and neuronal death.Tau has been shown to aggregate in synapses which may impair restorative synapse processes occurring during sleep. However, it remains unclear how sleep disruption and synaptic Tau pathology interact to drive cognitive decline. It is also unclear whether the sexes show differential vulnerability to the effects of sleep loss in the context of neurodegeneration. Methods: We used a piezoelectric home-cage monitoring system to measure sleep behavior in 3-11month-old transgenic hTau P301S Tauopathy model mice (PS19) and littermate controls of both sexes. Subcellular fractionation and Western blot was used to examine Tau pathology in mouse forebrain synapse fractions. To examine the role of sleep disruption in disease progression, mice were exposed to acute or chronic sleep disruption. The Morris water maze test was used to measure spatial learning and memory performance. Results: PS19 mice exhibited a selective loss of sleep during the dark phase, referred to as hyperarousal, as an early symptom with an onset of 3months in females and 6months in males. At 6months, forebrain synaptic Tau burden did not correlate with sleep measures and was not affected by acute or chronic sleep disruption. Chronic sleep disruption accelerated the onset of decline of hippocampal spatial memory in PS19 males, but not females. Conclusions: Dark phase hyperarousal is an early symptom in PS19 mice that precedes robust Tau aggregation. We find no evidence that sleep disruption is a direct driver of Tau pathology in the forebrain synapse. However, sleep disruption synergized with Tau pathology to accelerate the onset of cognitive decline in males. Despite the finding that hyperarousal appears earlier in females, female cognition was resilient to the effects of sleep disruption.
RESUMEN
Transactive response DNA-binding protein of 43 kDa (TDP-43) is a highly conserved, ubiquitously expressed nucleic acid-binding protein that regulates DNA/RNA metabolism. Genetics and neuropathology studies have linked TDP-43 to several neuromuscular and neurological disorders including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Under pathological conditions, TDP-43 mislocalizes to the cytoplasm where it forms insoluble, hyper-phosphorylated aggregates during disease progression. Here, we optimized a scalable in vitro immuno-purification strategy referred to as tandem detergent-extraction and immunoprecipitation of proteinopathy (TDiP) to isolate TDP-43 aggregates that recapitulate those identified in postmortem ALS tissue. Moreover, we demonstrate that these purified aggregates can be utilized in biochemical, proteomics, and live-cell assays. This platform offers a rapid, accessible, and streamlined approach to study ALS disease mechanisms, while overcoming many limitations that have hampered TDP-43 disease modeling and therapeutic drug discovery efforts.
RESUMEN
Tau-mediated toxicity is associated with cognitive decline and Alzheimer's disease (AD) progression. In particular, tau post-translational modifications (PTMs) are thought to generate aberrant tau species resulting in neuronal dysfunction. Despite being well characterized in postmortem AD brain, it is unclear how caspase-mediated C-terminal tau cleavage promotes neurodegeneration, as few studies have developed the models to dissect this pathogenic mechanism. Here, we show that proteasome impairment results in cleaved tau accumulation at the post-synaptic density (PSD), a process that is modulated by neuronal activity. Cleaved tau (at residue D421) impairs neuronal firing and causes inefficient initiation of network bursts, consistent with reduced excitatory drive. We propose that reduced neuronal activity, or silencing, is coupled to proteasome dysfunction, which drives cleaved tau accumulation at the PSD and subsequent synaptotoxicity. Our study connects three common themes in the progression of AD: impaired proteostasis, caspase-mediated tau cleavage, and synapse degeneration.
RESUMEN
TDP-43 proteinopathies including frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative disorders characterized by aggregation and mislocalization of the nucleic acid-binding protein TDP-43 and subsequent neuronal dysfunction. Here, we developed endogenous models of sporadic TDP-43 proteinopathy based on the principle that disease-associated TDP-43 acetylation at lysine 145 (K145) alters TDP-43 conformation, impairs RNA-binding capacity, and induces downstream mis-regulation of target genes. Expression of acetylation-mimic TDP-43K145Q resulted in stress-induced nuclear TDP-43 foci and loss of TDP-43 function in primary mouse and human-induced pluripotent stem cell (hiPSC)-derived cortical neurons. Mice harboring the TDP-43K145Q mutation recapitulated key hallmarks of FTLD, including progressive TDP-43 phosphorylation and insolubility, TDP-43 mis-localization, transcriptomic and splicing alterations, and cognitive dysfunction. Our study supports a model in which TDP-43 acetylation drives neuronal dysfunction and cognitive decline through aberrant splicing and transcription of critical genes that regulate synaptic plasticity and stress response signaling. The neurodegenerative cascade initiated by TDP-43 acetylation recapitulates many aspects of human FTLD and provides a new paradigm to further interrogate TDP-43 proteinopathies.
Asunto(s)
Esclerosis Amiotrófica Lateral , Disfunción Cognitiva , Demencia Frontotemporal , Degeneración Lobar Frontotemporal , Proteinopatías TDP-43 , Humanos , Animales , Ratones , Proteinopatías TDP-43/genética , Proteinopatías TDP-43/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Degeneración Lobar Frontotemporal/genética , Degeneración Lobar Frontotemporal/metabolismo , Esclerosis Amiotrófica Lateral/genética , Demencia Frontotemporal/genética , Modelos Animales de Enfermedad , ARNRESUMEN
CONTEXT: During the COVID-19 pandemic, essential in-person electrocardiogram (ECG) recordings became unfeasible, while patients continued to suffer from cardiac conditions. To circumvent these challenges, the cardiology clinic (Long Island Heart Rhythm Center [LIHRC]) at the New York Institute of Technology College of Osteopathic Medicine (NYITCOM) transitioned to a remote real-time outpatient cardiac telemetry (ROCT) service. OBJECTIVES: The goal of this study is to test the hypothesis that at-home ROCT, provided by the LIHRC, is an effective method of providing ECG monitoring to symptomatic patients during the COVID-19 pandemic. METHODS: Seventeen patients at the LIHRC that required ECGs between March 11 and August 1, 2020, were included in this study. The patients' medical records were de-identified and reviewed for age, gender, ROCT indications, findings, patient comfort, and ease of use. A retrospective analysis of observational de-identified data obtained from the LIHRC was approved and permitted by the NYITCOM Institutional Review Board (BHS-1465). These FDA-cleared medical devices (DMS-300, DM Software, Stateline, NV) were shipped to the patients' homes and were self-applied through adhesive chest patches. The devices communicated with a cloud-based system that produced reports including a continuous 6-lead ECG and many other cardiovascular parameters. Additionally, a patient-activated symptom recorder was available to correlate symptoms to ECG findings. RESULTS: Seventeen patients (15 women) from the LIHRC were included in the analysis with an average monitoring duration of 27 h (range, 24-72 h). The patients' ages ranged from 21 to 85 years old with a mean of 37 years old and a standard deviation of 19. ROCT indications included palpitations (n=9), presyncope (n=8), chest pain (n=5), syncope (n=3), and shortness of breath (n=2). One also received ROCT due to short PR intervals observed on a prepandemic ECG. Two patients experienced palpitations while wearing the ROCT device: one had supraventricular tachycardia at 150 beats per minute; the other had unifocal premature ventricular contractions (PVCs) and eventually underwent a successful cardiac ablation. Most patients experienced no symptomatic episodes during ROCT (n=15). The 6-lead ROCT ECG for five of those patients showed arrhythmias including wandering atrial pacemaker (n=2), PVCs (n=2), sinus tachycardia (n=1), premature atrial contractions (PACs) (n=1), ectopic atrial rhythms (n=1), and sinus arrhythmia (n=1). One patient who experienced issues with our device was able to obtain a device from a separate clinic and was found to have bradycardia, PVCs, and nonsustained ventricular tachycardia. Overall, 16/17 (94.1%) patients were monitored effectively with the LIHRC ROCT system, and all (17/17, 100%) patients were monitored effectively with a ROCT system either from the LIHRC or a separate clinic. CONCLUSIONS: With the unique challenges of the COVID-19 pandemic, physicians can use this innovative ROCT method to prevent infection and diagnose cardiac diseases. Most patients and staff were able to utilize the system without issues. Therefore, this system may also be utilized to deliver patient-centered care to those with limited mobility when coupled with a telemedicine visit.
Asunto(s)
COVID-19 , Electrocardiografía Ambulatoria , Adulto , Anciano , Anciano de 80 o más Años , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/epidemiología , COVID-19/epidemiología , Electrocardiografía , Electrocardiografía Ambulatoria/métodos , Femenino , Humanos , Persona de Mediana Edad , Pacientes Ambulatorios , Pandemias , Estudios Retrospectivos , Telemetría , Adulto JovenRESUMEN
Corpora amylacea (CA) and their murine analogs, periodic acid Schiff (PAS) granules, are age-related, carbohydrate-rich structures that serve as waste repositories for aggregated proteins, damaged cellular organelles, and other cellular debris. The structure, morphology, and suspected functions of CA in the brain imply disease relevance. Despite this, the link between CA and age-related neurodegenerative diseases, particularly Alzheimer's disease (AD), remains poorly defined. We performed a neuropathological analysis of mouse PAS granules and human CA and correlated these findings with AD progression. Increased PAS granule density was observed in symptomatic tau transgenic mice and APOE knock-in mice. Using a cohort of postmortem AD brain samples, we examined CA in cognitively normal and dementia patients across Braak stages with varying APOE status. We identified a Braak-stage dependent bimodal distribution of CA in the dentate gyrus, with CA accumulating and peaking by Braak stages II-III, then steadily declining with increasing tau burden. Refined analysis revealed an association of CA levels with both cognition and APOE status. Finally, tau was detected in whole CA present in human patient cerebrospinal fluid, highlighting CA-tau as a plausible prodromal AD biomarker. Our study connects hallmarks of the aging brain with the emergence of AD pathology and suggests that CA may act as a compensatory factor that becomes depleted with advancing tau burden.