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1.
J Vis Exp ; (175)2021 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-34570098

RESUMO

The nuclear pore complex (NPC) is a complex macromolecular structure comprised of multiple copies of ~30 different nucleoporin proteins (Nups). Collectively, these Nups function to regulate genome organization, gene expression, and nucleocytoplasmic transport (NCT). Recently, defects in NCT and alterations to specific Nups have been identified as early and prominent pathologies in multiple neurodegenerative diseases, including Amyotrophic Lateral Sclerosis (ALS), Alzheimer's Disease (AD)/Frontotemporal Dementia (FTD), and Huntington's Disease (HD). Advances in both light and electron microscopy allow for a thorough examination of sub-cellular structures, including the NPC and its Nup constituents, with increased precision and resolution. Of the commonly used techniques, super-resolution structured illumination microscopy (SIM) affords the unparalleled opportunity to study the localization and expression of individual Nups using conventional antibody-based labeling strategies. Isolation of nuclei prior to SIM enables the visualization of individual Nup proteins within the NPC and nucleoplasm in fully and accurately reconstructed 3D space. This protocol describes a procedure for nuclei isolation and SIM to evaluate Nup expression and distribution in human iPSC-derived CNS cells and postmortem tissues.

2.
J Clin Invest ; 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34491913

RESUMO

Peripheral nerves have the capacity for regeneration, but the rate of regeneration is so slow that many nerve injuries lead to incomplete recovery and permanent disability for patients. Macrophages play a critical role in the peripheral nerve response to injury, both for Wallerian degeneration and for contributing to regeneration, and their function has recently been shown to be dependent on intracellular metabolism. To date, the impact of their intracellular metabolism on peripheral nerve regeneration has not been studied. Examining conditional transgenic mice with selective ablation of solute carrier family 16, member 1 (Slc16a1, which encodes the monocarboxylate transporter 1, MCT1) in macrophages, we found that MCT1 contributes to macrophage metabolism, phenotype, and function, specifically in regard to phagocytosis and supporting peripheral nerve regeneration. Adoptive cell transfer of wild-type macrophages ameliorated the impaired nerve regeneration in macrophage-selective MCT1 null mice. We also developed a mouse model that overexpresses MCT1 in macrophages and found that peripheral nerves in these mice regenerated more rapidly than control mice. Our study provides further evidence that MCT1 has an important biological role in macrophages and that manipulations of macrophage metabolism can enhance recovery from peripheral nerve injuries, for which there are currently no approved medical therapies.

3.
Nat Commun ; 12(1): 4908, 2021 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-34389711

RESUMO

C9ORF72 hexanucleotide GGGGCC repeat expansion is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Repeat-containing RNA mediates toxicity through nuclear granules and dipeptide repeat (DPR) proteins produced by repeat-associated non-AUG translation. However, it remains unclear how the intron-localized repeats are exported and translated in the cytoplasm. We use single molecule imaging approach to examine the molecular identity and spatiotemporal dynamics of the repeat RNA. We demonstrate that the spliced intron with G-rich repeats is stabilized in a circular form due to defective lariat debranching. The spliced circular intron, instead of pre-mRNA, serves as the translation template. The NXF1-NXT1 pathway plays an important role in the nuclear export of the circular intron and modulates toxic DPR production. This study reveals an uncharacterized disease-causing RNA species mediated by repeat expansion and demonstrates the importance of RNA spatial localization to understand disease etiology.


Assuntos
Proteína C9orf72/genética , Núcleo Celular/metabolismo , Íntrons/genética , Biossíntese de Proteínas/genética , RNA/genética , Transporte Ativo do Núcleo Celular/genética , Esclerose Amiotrófica Lateral/genética , Esclerose Amiotrófica Lateral/metabolismo , Proteína C9orf72/metabolismo , Linhagem Celular Tumoral , Núcleo Celular/genética , Expansão das Repetições de DNA/genética , Dipeptídeos/genética , Dipeptídeos/metabolismo , Demência Frontotemporal/genética , Demência Frontotemporal/metabolismo , Predisposição Genética para Doença/genética , Células HEK293 , Humanos , Microscopia de Fluorescência , Proteínas de Transporte Nucleocitoplasmático/genética , Proteínas de Transporte Nucleocitoplasmático/metabolismo , RNA/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/genética
4.
Acta Neuropathol Commun ; 9(1): 127, 2021 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-34281622

RESUMO

Nuclear pore complex injury has recently emerged as an early and significant contributor to familial and sporadic ALS disease pathogenesis. However, the molecular events leading to this pathological phenomenon characterized by the reduction of specific nucleoporins from neuronal nuclear pore complexes remain largely unknown. This is due in part to a lack of knowledge regarding the biological pathways and proteins underlying nuclear pore complex homeostasis specifically in human neurons. We have recently uncovered that aberrant nuclear accumulation of the ESCRT-III protein CHMP7 initiates nuclear pore complex in familial and sporadic ALS neurons. In yeast and non-neuronal mammalian cells, nuclear relocalization of CHMP7 has been shown to recruit the ESCRT-III proteins CHMP4B, CHMP2B, and VPS4 to facilitate nuclear pore complex and nuclear envelope repair and homeostasis. Here, using super resolution structured illumination microscopy, we find that neither CHMP4B nor CHMP2B are increased in ALS neuronal nuclei. In contrast, VPS4 expression is significantly increased in ALS neuronal nuclei prior to the emergence of nuclear pore injury in a CHMP7 dependent manner. However, unlike our prior CHMP7 knockdown studies, impaired VPS4 function does not mitigate alterations to the NPC and the integral transmembrane nucleoporin POM121. Collectively our data suggest that while alterations in VPS4 subcellular localization appear to be coincident with nuclear pore complex injury, therapeutic efforts to mitigate this pathogenic cascade should be targeted towards upstream events such as the nuclear accumulation of CHMP7 as we have previously described.

5.
Sci Transl Med ; 13(604)2021 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-34321318

RESUMO

Alterations in the components [nucleoporins (Nups)] and function of the nuclear pore complex (NPC) have been implicated as contributors to the pathogenesis of genetic forms of neurodegeneration including C9orf72 amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD). We hypothesized that Nup alterations and the consequential loss of NPC function may lie upstream of TDP-43 dysfunction and mislocalization widely observed in ALS, FTD, and related neurodegenerative diseases. Here, we provide evidence that CHMP7, a critical mediator of NPC quality control, is increased in nuclei of C9orf72 and sporadic ALS induced pluripotent stem cell (iPSC)-derived spinal neurons (iPSNs) and postmortem human motor cortex before the emergence of Nup alterations. Inhibiting the nuclear export of CHMP7 triggered Nup reduction and TDP-43 dysfunction and pathology in human neurons. Knockdown of CHMP7 alleviated disease-associated Nup alterations, deficits in Ran GTPase localization, defects in TDP-43-associated mRNA expression, and downstream glutamate-induced neuronal death. Thus, our data support a role for altered CHMP7-mediated Nup homeostasis as a prominent initiating pathological mechanism for familial and sporadic ALS and highlight the potential for CHMP7 as therapeutic target.


Assuntos
Esclerose Amiotrófica Lateral , Demência Frontotemporal , Esclerose Amiotrófica Lateral/genética , Proteína C9orf72/genética , Proteínas de Ligação a DNA/genética , Complexos Endossomais de Distribuição Requeridos para Transporte , Demência Frontotemporal/genética , Humanos , Poro Nuclear
6.
J Am Chem Soc ; 143(19): 7368-7379, 2021 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-33855846

RESUMO

The expansion of a hexanucleotide repeat GGGGCC (G4C2) in the C9orf72 gene is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The G4C2 expansion leads to repeat-associated non-AUG (RAN) translation and the production of toxic dipeptide repeat (DPR) proteins, but the mechanisms of RAN translation remain enigmatic. Here, we report that the RNA helicase DHX36 is a robust positive regulator of C9orf72 RAN translation. DHX36 has a high affinity for the G4C2 repeat RNA, preferentially binds to the repeat RNA's G-quadruplex conformation, and efficiently unwinds the G4C2 G-quadruplex structures. Native DHX36 interacts with the G4C2 repeat RNA and is essential for effective RAN translation in the cell. In induced pluripotent stem cells and differentiated motor neurons derived from C9orf72-linked ALS patients, reducing DHX36 significantly decreased the levels of endogenous DPR proteins. DHX36 is also aberrantly upregulated in tissues of C9orf72-linked ALS patients. These results indicate that DHX36 facilitates C9orf72 RAN translation by resolving repeat RNA G-quadruplex structures and may be a potential target for therapeutic intervention.

7.
Cell Rep ; 34(13): 108925, 2021 03 30.
Artigo em Inglês | MEDLINE | ID: mdl-33789100

RESUMO

Multiple cellular pathways have been suggested to be altered by the C9orf72 GGGGCC (G4C2) hexanucleotide repeat expansion (HRE), including aspects of RNA regulation such as nonsense-mediated decay (NMD). Here, we investigate the role that overexpression of UPF1, a protein involved in NMD, plays in mitigating neurotoxicity in multiple models of C9orf72 ALS/FTD. First, we show that NMD is not altered in our endogenous induced pluripotent stem cell (iPSC)-derived spinal neuron (iPSN) model of C9orf72 ALS (C9-ALS) or postmortem motor cortex tissue from C9-ALS patients. Unexpectedly, we find that UPF1 overexpression significantly reduces the severity of known neurodegenerative phenotypes without altering NMD function itself. UPF1 overexpression reduces poly(GP) abundance without altering the amount of repeat RNA, providing a potential mechanism by which UPF1 reduces dipeptide repeat (DPR) protein-mediated toxicity. Together, these findings indicate that UPF1 is neuroprotective in the context of C9-ALS, albeit independent of known UPF1-mediated NMD pathways.

8.
Acta Neuropathol Commun ; 9(1): 45, 2021 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-33741069

RESUMO

The most common genetic cause of familial and sporadic amyotrophic lateral sclerosis (ALS) is a GGGGCC hexanucleotide repeat expansion (HRE) in the C9orf72 gene. While direct molecular hallmarks of the C9orf72 HRE (repeat RNA foci, dipeptide repeat protein pathology) are well characterized, the mechanisms by which the C9orf72 HRE causes ALS and the related neurodegenerative disease frontotemporal dementia (FTD) remain poorly understood. Recently, alterations to the nuclear pore complex and nucleocytoplasmic transport have been accepted as a prominent pathomechanism underlying C9orf72 ALS/FTD. However, global disruptions to nuclear morphology and the nuclear lamina itself remain controversial. Here, we use a large number of induced pluripotent stem cell derived spinal neurons and postmortem human motor cortex sections to thoroughly examine nuclear morphology and nuclear lamina disruptions with light microscopy. In contrast to previous studies in artificial overexpression model systems, endogenous levels of the C9orf72 HRE do not increase the frequency of nuclear lamina invaginations. In addition, the C9orf72 HRE has no impact on overall nuclear shape and size. Notably, the frequency of nuclear Lamin B1 invaginations increases with cellular aging, independent of the C9orf72 HRE. Together, our data suggest that nuclear morphology is unaltered in C9orf72 ALS/FTD.

9.
Nature ; 591(7851): 645-651, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33589820

RESUMO

Regulatory T (Treg) cells, although vital for immune homeostasis, also represent a major barrier to anti-cancer immunity, as the tumour microenvironment (TME) promotes the recruitment, differentiation and activity of these cells1,2. Tumour cells show deregulated metabolism, leading to a metabolite-depleted, hypoxic and acidic TME3, which places infiltrating effector T cells in competition with the tumour for metabolites and impairs their function4-6. At the same time, Treg cells maintain a strong suppression of effector T cells within the TME7,8. As previous studies suggested that Treg cells possess a distinct metabolic profile from effector T cells9-11, we hypothesized that the altered metabolic landscape of the TME and increased activity of intratumoral Treg cells are linked. Here we show that Treg cells display broad heterogeneity in their metabolism of glucose within normal and transformed tissues, and can engage an alternative metabolic pathway to maintain suppressive function and proliferation. Glucose uptake correlates with poorer suppressive function and long-term instability, and high-glucose conditions impair the function and stability of Treg cells in vitro. Treg cells instead upregulate pathways involved in the metabolism of the glycolytic by-product lactic acid. Treg cells withstand high-lactate conditions, and treatment with lactate prevents the destabilizing effects of high-glucose conditions, generating intermediates necessary for proliferation. Deletion of MCT1-a lactate transporter-in Treg cells reveals that lactate uptake is dispensable for the function of peripheral Treg cells but required intratumorally, resulting in slowed tumour growth and an increased response to immunotherapy. Thus, Treg cells are metabolically flexible: they can use 'alternative' metabolites in the TME to maintain their suppressive identity. Further, our results suggest that tumours avoid destruction by not only depriving effector T cells of nutrients, but also metabolically supporting regulatory populations.

10.
Cell Rep ; 34(2): 108610, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33440165

RESUMO

Oligodendrocytes (OLs) are important for myelination and shuttling energy metabolites lactate and pyruvate toward axons through their expression of monocarboxylate transporter 1 (MCT1). Recent studies suggest that loss of OL MCT1 causes axonal degeneration. However, it is unknown how widespread and chronic loss of MCT1 in OLs specifically affects neuronal energy homeostasis with aging. To answer this, MCT1 conditional null mice were generated that allow for OL-specific MCT1 ablation. We observe that MCT1 loss from OL lineage cells is dispensable for normal myelination and axonal energy homeostasis early in life. By contrast, loss of OL lineage MCT1 expression with aging leads to significant axonal degeneration with concomitant hypomyelination. These data support the hypothesis that MCT1 is important for neuronal energy homeostasis in the aging central nervous system (CNS). The reduction in OL MCT1 that occurs with aging may enhance the risk for axonal degeneration and atrophy in neurodegenerative diseases.

11.
Muscle Nerve ; 63(1): 31-39, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33063909

RESUMO

An orally administered, fixed-dose coformulation of sodium phenylbutyrate-taurursodiol (PB-TURSO) significantly slowed functional decline in a randomized, placebo-controlled, phase 2 trial in ALS (CENTAUR). Herein we report results of a long-term survival analysis of participants in CENTAUR. In CENTAUR, adults with ALS were randomized 2:1 to PB-TURSO or placebo. Participants completing the 6-month (24-week) randomized phase were eligible to receive PB-TURSO in the open-label extension. An all-cause mortality analysis (35-month maximum follow-up post-randomization) incorporated all randomized participants. Participants and site investigators were blinded to treatment assignments through the duration of follow-up of this analysis. Vital status was obtained for 135 of 137 participants originally randomized in CENTAUR. Median overall survival was 25.0 months among participants originally randomized to PB-TURSO and 18.5 months among those originally randomized to placebo (hazard ratio, 0.56; 95% confidence interval, 0.34-0.92; P = .023). Initiation of PB-TURSO treatment at baseline resulted in a 6.5-month longer median survival as compared with placebo. Combined with results from CENTAUR, these results suggest that PB-TURSO has both functional and survival benefits in ALS.


Assuntos
Esclerose Amiotrófica Lateral/tratamento farmacológico , Esclerose Amiotrófica Lateral/mortalidade , Fármacos Neuroprotetores/uso terapêutico , Fenilbutiratos/uso terapêutico , Ácido Tauroquenodesoxicólico/uso terapêutico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tempo , Adulto Jovem
12.
Elife ; 92020 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-33300868

RESUMO

Disrupted nucleocytoplasmic transport (NCT) has been implicated in neurodegenerative disease pathogenesis; however, the mechanisms by which disrupted NCT causes neurodegeneration remain unclear. In a Drosophila screen, we identified ref(2)P/p62, a key regulator of autophagy, as a potent suppressor of neurodegeneration caused by the GGGGCC hexanucleotide repeat expansion (G4C2 HRE) in C9orf72 that causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). We found that p62 is increased and forms ubiquitinated aggregates due to decreased autophagic cargo degradation. Immunofluorescence and electron microscopy of Drosophila tissues demonstrate an accumulation of lysosome-like organelles that precedes neurodegeneration. These phenotypes are partially caused by cytoplasmic mislocalization of Mitf/TFEB, a key transcriptional regulator of autophagolysosomal function. Additionally, TFEB is mislocalized and downregulated in human cells expressing GGGGCC repeats and in C9-ALS patient motor cortex. Our data suggest that the C9orf72-HRE impairs Mitf/TFEB nuclear import, thereby disrupting autophagy and exacerbating proteostasis defects in C9-ALS/FTD.


Assuntos
Transporte Ativo do Núcleo Celular/genética , Autofagia , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/fisiologia , Fator de Transcrição Associado à Microftalmia/fisiologia , Esclerose Amiotrófica Lateral/genética , Animais , Autofagia/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Western Blotting , Proteína C9orf72/genética , Modelos Animais de Doenças , Drosophila melanogaster , Feminino , Imunofluorescência , Demência Frontotemporal/genética , Células HeLa , Humanos , Lisossomos/genética , Masculino , Fator de Transcrição Associado à Microftalmia/metabolismo , Microscopia Eletrônica de Transmissão , Córtex Motor/metabolismo
13.
Neuron ; 108(4): 775-783.e4, 2020 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-33022228

RESUMO

A hexanucleotide repeat expansion at C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD). Initial studies of bacterial artificial chromosome (BAC) transgenic mice harboring this expansion described an absence of motor and survival phenotypes. However, a recent study by Liu and colleagues described transgenic mice harboring a large repeat expansion (C9-500) and reported decreased survival and progressive motor phenotypes. To determine the utility of the C9-500 animals for understanding degenerative mechanisms, we validated and established two independent colonies of transgene carriers. However, extended studies of these animals for up to 1 year revealed no reproducible abnormalities in survival, motor function, or neurodegeneration. Here, we propose several potential explanations for the disparate nature of our findings from those of Liu and colleagues. Resolving the discrepancies we identify will be essential to settle the translational utility of C9-500 mice. This Matters Arising paper is in response to Liu et al. (2016), published in Neuron. See also the response by Nguyen et al. (2020), published in this issue.


Assuntos
Esclerose Amiotrófica Lateral/fisiopatologia , Proteína C9orf72/fisiologia , Destreza Motora/fisiologia , Degeneração Neural/fisiopatologia , Sobrevida/fisiologia , Esclerose Amiotrófica Lateral/genética , Animais , Proteína C9orf72/genética , Expansão das Repetições de DNA/genética , Modelos Animais de Doenças , Heterozigoto , Masculino , Camundongos , Camundongos Transgênicos , Fenótipo
14.
N Engl J Med ; 383(10): 919-930, 2020 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-32877582

RESUMO

BACKGROUND: Sodium phenylbutyrate and taurursodiol have been found to reduce neuronal death in experimental models. The efficacy and safety of a combination of the two compounds in persons with amyotrophic lateral sclerosis (ALS) are not known. METHODS: In this multicenter, randomized, double-blind trial, we enrolled participants with definite ALS who had had an onset of symptoms within the previous 18 months. Participants were randomly assigned in a 2:1 ratio to receive sodium phenylbutyrate-taurursodiol (3 g of sodium phenylbutyrate and 1 g of taurursodiol, administered once a day for 3 weeks and then twice a day) or placebo. The primary outcome was the rate of decline in the total score on the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-R; range, 0 to 48, with higher scores indicating better function) through 24 weeks. Secondary outcomes were the rates of decline in isometric muscle strength, plasma phosphorylated axonal neurofilament H subunit levels, and the slow vital capacity; the time to death, tracheostomy, or permanent ventilation; and the time to death, tracheostomy, permanent ventilation, or hospitalization. RESULTS: A total of 177 persons with ALS were screened for eligibility, and 137 were randomly assigned to receive sodium phenylbutyrate-taurursodiol (89 participants) or placebo (48 participants). In a modified intention-to-treat analysis, the mean rate of change in the ALSFRS-R score was -1.24 points per month with the active drug and -1.66 points per month with placebo (difference, 0.42 points per month; 95% confidence interval, 0.03 to 0.81; P = 0.03). Secondary outcomes did not differ significantly between the two groups. Adverse events with the active drug were mainly gastrointestinal. CONCLUSIONS: Sodium phenylbutyrate-taurursodiol resulted in slower functional decline than placebo as measured by the ALSFRS-R score over a period of 24 weeks. Secondary outcomes were not significantly different between the two groups. Longer and larger trials are necessary to evaluate the efficacy and safety of sodium phenylbutyrate-taurursodiol in persons with ALS. (Funded by Amylyx Pharmaceuticals and others; CENTAUR ClinicalTrials.gov number, NCT03127514.).


Assuntos
Esclerose Amiotrófica Lateral/tratamento farmacológico , Fenilbutiratos/uso terapêutico , Ácido Tauroquenodesoxicólico/uso terapêutico , Idoso , Progressão da Doença , Método Duplo-Cego , Combinação de Medicamentos , Feminino , Humanos , Análise de Intenção de Tratamento , Masculino , Pessoa de Meia-Idade , Fenilbutiratos/efeitos adversos , Índice de Gravidade de Doença , Ácido Tauroquenodesoxicólico/administração & dosagem , Resultado do Tratamento
15.
Neuron ; 107(6): 1124-1140.e11, 2020 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-32673563

RESUMO

Through mechanisms that remain poorly defined, defects in nucleocytoplasmic transport and accumulations of specific nuclear-pore-complex-associated proteins have been reported in multiple neurodegenerative diseases, including C9orf72 Amyotrophic Lateral Sclerosis and Frontotemporal Dementia (ALS/FTD). Using super-resolution structured illumination microscopy, we have explored the mechanism by which nucleoporins are altered in nuclei isolated from C9orf72 induced pluripotent stem-cell-derived neurons (iPSNs). Of the 23 nucleoporins evaluated, we observed a reduction in a subset of 8, including key components of the nuclear pore complex scaffold and the transmembrane nucleoporin POM121. Reduction in POM121 appears to initiate a decrease in the expression of seven additional nucleoporins, ultimately affecting the localization of Ran GTPase and subsequent cellular toxicity in C9orf72 iPSNs. Collectively, our data suggest that the expression of expanded C9orf72 ALS/FTD repeat RNA alone affects nuclear POM121 expression in the initiation of a pathological cascade affecting nucleoporin levels within neuronal nuclei and ultimately downstream neuronal survival.


Assuntos
Esclerose Amiotrófica Lateral/metabolismo , Proteína C9orf72/genética , Demência Frontotemporal/metabolismo , Glicoproteínas de Membrana/genética , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Transporte Ativo do Núcleo Celular , Esclerose Amiotrófica Lateral/genética , Proteína C9orf72/metabolismo , Células Cultivadas , Demência Frontotemporal/genética , Células HEK293 , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/metabolismo , Glicoproteínas de Membrana/metabolismo , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Poro Nuclear/metabolismo , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo
16.
Muscle Nerve ; 62(2): 182-186, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32445195

RESUMO

Coronavirus disease 2019 has created unprecedented challenges for amyotrophic lateral sclerosis (ALS) clinical care and research in the United States. Traditional evaluations for making an ALS diagnosis, measuring progression, and planning interventions rely on in-person visits that may now be unsafe or impossible. Evidence- and experience-based treatment options, such as multidisciplinary team care, feeding tubes, wheelchairs, home health, and hospice, have become more difficult to obtain and in some places are unavailable. In addition, the pandemic has impacted ALS clinical trials by impairing the ability to obtain measurements for trial eligibility, to monitor safety and efficacy outcomes, and to dispense study drug, as these also often rely on in-person visits. We review opportunities for overcoming some of these challenges through telemedicine and novel measurements. These can reoptimize ALS care and research in the current setting and during future events that may limit travel and face-to-face interactions.


Assuntos
Esclerose Amiotrófica Lateral/terapia , Infecções por Coronavirus/epidemiologia , Acesso aos Serviços de Saúde , Serviços de Assistência Domiciliar , Cuidados Paliativos na Terminalidade da Vida , Pneumonia Viral/epidemiologia , Telemedicina , Esclerose Amiotrófica Lateral/diagnóstico , Betacoronavirus , Pesquisa Biomédica , COVID-19 , Ensaios Clínicos como Assunto , Nutrição Enteral , Humanos , Pandemias , SARS-CoV-2 , Espirometria , Estados Unidos/epidemiologia , Ventiladores Mecânicos , Cadeiras de Rodas
17.
Elife ; 92020 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-32119645

RESUMO

Disruption of nucleocytoplasmic transport is increasingly implicated in the pathogenesis of neurodegenerative diseases, including ALS caused by a C9orf72 hexanucleotide repeat expansion. However, the mechanism(s) remain unclear. Karyopherins, including importin ß and its cargo adaptors, have been shown to co-precipitate with the C9orf72 arginine-containing dipeptide repeat proteins (R-DPRs), poly-glycine arginine (GR) and poly-proline arginine (PR), and are protective in genetic modifier screens. Here, we show that R-DPRs interact with importin ß, disrupt its cargo loading, and inhibit nuclear import of importin ß, importin α/ß, and transportin cargoes in permeabilized mouse neurons and HeLa cells, in a manner that can be rescued by RNA. Although R-DPRs induce widespread protein aggregation in this in vitro system, transport disruption is not due to nucleocytoplasmic transport protein sequestration, nor blockade of the phenylalanine-glycine (FG)-rich nuclear pore complex. Our results support a model in which R-DPRs interfere with cargo loading on karyopherins.


Assuntos
Arginina/metabolismo , Proteína C9orf72/metabolismo , Dipeptídeos/metabolismo , Carioferinas/metabolismo , Transporte Ativo do Núcleo Celular , Esclerose Amiotrófica Lateral/metabolismo , Animais , Proteína C9orf72/química , Humanos , Camundongos , Ligação Proteica , beta Carioferinas/metabolismo
18.
Neurochem Res ; 45(6): 1298-1305, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32006215

RESUMO

Astrocytes make up 20-40% of glial cells within the central nervous system (CNS) and provide several crucial functions, ranging from metabolic and structural support to regulation of synaptogenesis and synaptic transmission. Although these cells are morphologically and functionally complex, astrocytes have been historically regarded as homogenous cell populations and studied as one population of cells. Fortunately, recent evidence in RNA profiling and imaging data has begun to refute this view. These studies suggest heterogeneity of astrocytes across brain regions, differing in many aspects such as morphology, function, physiological properties, developmental origins, and response to disease. Increased understanding of astrocyte heterogeneity is critical for investigations into the function of astrocytes in the brain and neuro-glia interactions. Furthermore, insights into astrocyte heterogeneity can help better understand their role in neurological disorders and potentially produce novel approaches to treating these diseases.


Assuntos
Astrócitos/fisiologia , Encéfalo/fisiologia , Neurogênese/fisiologia , Neurônios/fisiologia , Animais , Encéfalo/citologia , Previsões , Humanos , Doenças do Sistema Nervoso/patologia
19.
Glia ; 68(1): 161-177, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31453649

RESUMO

Schwann cell (SC)-specific monocarboxylate transporter 1 (MCT1) knockout mice were generated by mating MCT1 f/f mice with myelin protein zero (P0)-Cre mice. P0-Cre+/- , MCT1 f/f mice have no detectable early developmental defects, but develop hypomyelination and reduced conduction velocity in sensory, but not motor, peripheral nerves during maturation and aging. Furthermore, reduced mechanical sensitivity is evident in aged P0-Cre+/- , MCT1 f/f mice. MCT1 deletion in SCs impairs both their glycolytic and mitochondrial functions, leading to altered lipid metabolism of triacylglycerides, diacylglycerides, and sphingomyelin, decreased expression of myelin-associated glycoprotein, and increased expression of c-Jun and p75-neurotrophin receptor, suggesting a regression of SCs to a less mature developmental state. Taken together, our results define the contribution of SC MCT1 to both SC metabolism and peripheral nerve maturation and aging.


Assuntos
Envelhecimento/metabolismo , Transportadores de Ácidos Monocarboxílicos/metabolismo , Bainha de Mielina/metabolismo , Células de Schwann/metabolismo , Células Receptoras Sensoriais/metabolismo , Simportadores/metabolismo , Envelhecimento/genética , Animais , Células Cultivadas , Feminino , Masculino , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Transportadores de Ácidos Monocarboxílicos/deficiência , Transportadores de Ácidos Monocarboxílicos/genética , Bainha de Mielina/genética , Condução Nervosa/fisiologia , Nervo Sural/metabolismo , Simportadores/deficiência , Simportadores/genética
20.
Neuron ; 104(5): 885-898.e8, 2019 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-31587919

RESUMO

Hexanucleotide GGGGCC repeat expansion in C9ORF72 is the most prevalent genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). One pathogenic mechanism is the aberrant accumulation of dipeptide repeat (DPR) proteins produced by the unconventional translation of expanded RNA repeats. Here, we performed genome-wide CRISPR-Cas9 screens for modifiers of DPR protein production in human cells. We found that DDX3X, an RNA helicase, suppresses the repeat-associated non-AUG translation of GGGGCC repeats. DDX3X directly binds to (GGGGCC)n RNAs but not antisense (CCCCGG)n RNAs. Its helicase activity is essential for the translation repression. Reduction of DDX3X increases DPR levels in C9ORF72-ALS/FTD patient cells and enhances (GGGGCC)n-mediated toxicity in Drosophila. Elevating DDX3X expression is sufficient to decrease DPR levels, rescue nucleocytoplasmic transport abnormalities, and improve survival of patient iPSC-differentiated neurons. This work identifies genetic modifiers of DPR protein production and provides potential therapeutic targets for C9ORF72-ALS/FTD.


Assuntos
Esclerose Amiotrófica Lateral/metabolismo , Proteína C9orf72/biossíntese , RNA Helicases DEAD-box/metabolismo , Demência Frontotemporal/metabolismo , Animais , Sistemas CRISPR-Cas , Drosophila , Humanos , Biossíntese de Proteínas/fisiologia , Sequências Repetitivas de Ácido Nucleico
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