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Parkinson's disease is a neurodegenerative disorder primarily known for typical motor features that arise due to the loss of dopaminergic neurons in the substantia nigra. However, the precise molecular aetiology of the disease is still unclear. Several cellular pathways have been linked to Parkinson's disease, including the autophagy-lysosome pathway, α-synuclein aggregation and mitochondrial function. Interestingly, the mechanistic link between GBA1, the gene that encodes for lysosomal ß-glucocerebrosidase (GCase), and Parkinson's disease lies in the interplay between GCase functions in the lysosome and mitochondria. GCase mutations alter mitochondria-lysosome contact sites. In the lysosome, reduced GCase activity leads to glycosphingolipid build-up, disrupting lysosomal function and autophagy, thereby triggering α-synuclein accumulation. Additionally, α-synuclein aggregates reduce GCase activity, creating a self-perpetuating cycle of lysosomal dysfunction and α-synuclein accumulation. GCase can also be imported into the mitochondria, where it promotes the integrity and function of mitochondrial complex I. Thus, GCase mutations that impair its normal function increase oxidative stress in mitochondria, the compartment where dopamine is oxidized. In turn, the accumulation of oxidized dopamine adducts further impairs GCase activity, creating a second cycle of GCase dysfunction. The oxidative state triggered by GCase dysfunction can also induce mitochondrial DNA damage which, in turn, can cause dopaminergic cell death. In this review, we highlight the pivotal role of GCase in Parkinson's disease pathogenesis and discuss promising examples of GCase-based therapeutics, such as gene and enzyme replacement therapies, small molecule chaperones and substrate reduction therapies, among others, as potential therapeutic interventions.
Assuntos
Glucosilceramidase , Lisossomos , Mitocôndrias , Doença de Parkinson , Humanos , Glucosilceramidase/metabolismo , Glucosilceramidase/genética , Lisossomos/metabolismo , Mitocôndrias/metabolismo , Doença de Parkinson/metabolismo , Doença de Parkinson/genética , Animais , alfa-Sinucleína/metabolismo , Autofagia/fisiologia , MutaçãoRESUMO
Niemann-Pick type C (NPC) disease is a lysosomal storage disease (LSD) characterized by the buildup of endo-lysosomal cholesterol and glycosphingolipids due to loss of function mutations in the NPC1 and NPC2 genes. NPC patients can present with a broad phenotypic spectrum, with differences at the age of onset, rate of progression, severity, organs involved, effects on the central nervous system, and even response to pharmacological treatments. This article reviews the phenotypic variation of NPC and discusses its possible causes, such as the remaining function of the defective protein, modifier genes, sex, environmental cues, and splicing factors, among others. We propose that these factors should be considered when designing or repurposing treatments for this disease. Despite its seeming complexity, this proposition is not far-fetched, considering the expanding interest in precision medicine and easier access to multi-omics technologies.
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Identification of genetic modulators of lysosomal enzyme activities and glycosphingolipids (GSLs) may facilitate the development of therapeutics for diseases in which they participate, including Lysosomal Storage Disorders (LSDs). To this end, we used a systems genetics approach: we measured 11 hepatic lysosomal enzymes and many of their natural substrates (GSLs), followed by modifier gene mapping by GWAS and transcriptomics associations in a panel of inbred strains. Unexpectedly, most GSLs showed no association between their levels and the enzyme activity that catabolizes them. Genomic mapping identified 30 shared predicted modifier genes between the enzymes and GSLs, which are clustered in three pathways and are associated with other diseases. Surprisingly, they are regulated by ten common transcription factors, and their majority by miRNA-340p. In conclusion, we have identified novel regulators of GSL metabolism, which may serve as therapeutic targets for LSDs and may suggest the involvement of GSL metabolism in other pathologies.
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Glicoesfingolipídeos , Doenças por Armazenamento dos Lisossomos , Animais , Camundongos , Glicoesfingolipídeos/metabolismo , Doenças por Armazenamento dos Lisossomos/metabolismo , Hidrolases/metabolismo , Lisossomos/metabolismoRESUMO
We are all similar but a bit different. These differences are partially due to variations in our genomes and are related to the heterogeneity of symptoms and responses to treatments that patients exhibit. Most animal studies are performed in one single strain with one manipulation. However, due to the lack of variability, therapies are not always reproducible when treatments are translated to humans. Panels of already sequenced organisms are valuable tools for mimicking human phenotypic heterogeneities and gene mapping. This review summarizes the current knowledge of mouse, fly, and yeast panels with insightful applications for translational research.
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Saccharomyces cerevisiae , Pesquisa Translacional Biomédica , Animais , Mapeamento Cromossômico , Patrimônio Genético , Genoma , Humanos , Camundongos , Saccharomyces cerevisiae/genéticaRESUMO
Niemann-Pick type C disease (NPCD) is a lysosomal storage disorder caused by mutations in the NPC1 gene. The most affected tissues are the central nervous system and liver, and while significant efforts have been made to understand its neurological component, the pathophysiology of the liver damage remains unclear. In this study, hepatocytes derived from wild type and Npc1-/- mice were analyzed by mass spectrometry (MS)-based proteomics in conjunction with bioinformatic analysis. We identified 3832 proteins: 416 proteins had a p-value smaller than 0.05, of which 37% (n = 155) were considered differentially expressed proteins (DEPs), 149 of them were considered upregulated, and 6 were considered downregulated. We focused the analysis on pathways related to NPC pathogenic mechanisms, finding that the most significant changes in expression levels occur in proteins that function in the pathways of liver damage, lipid metabolism, and inflammation. Moreover, in the group of DEPs, 30% (n = 47) were identified as lysosomal proteins and 7% (n = 10) were identified as mitochondrial proteins. Importantly, we found that lysosomal DEPs, including CTSB/D/Z, LIPA, DPP7 and GLMP, and mitocondrial DEPs, AKR1B10, and VAT1 had been connected with liver fibrosis, damage, and steatosis in previous studies, validiting our dataset. Our study found potential therapeutic targets for the treatment of liver damage in NPCD.
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Hepatócitos/metabolismo , Fígado/metabolismo , Doença de Niemann-Pick Tipo C/metabolismo , Proteoma/metabolismo , Animais , Western Blotting , Células Cultivadas , Fígado/patologia , Hepatopatias/metabolismo , Hepatopatias/patologia , Masculino , CamundongosRESUMO
The acid ß-glucocerebrosidase (GCase) enzyme cleaves glucosylceramide into glucose and ceramide. Loss of function variants in the gene encoding for GCase can lead to Gaucher disease and Parkinson's disease. Therapeutic strategies aimed at increasing GCase activity by targeting a modulating factor are attractive and poorly explored. To identify genetic modifiers, we measured hepatic GCase activity in 27 inbred mouse strains. A genome-wide association study (GWAS) using GCase activity as a trait identified several candidate modifier genes, including Dmrtc2 and Arhgef1 (p=2.1x10-7), and Grik5 (p=2.1x10-7). Bayesian integration of the gene mapping with transcriptomics was used to build integrative networks. The analysis uncovered additional candidate GCase regulators, highlighting modules of the acute phase response (p=1.01x10-8), acute inflammatory response (p=1.01x10-8), fatty acid beta-oxidation (p=7.43x10-5), among others. Our study revealed previously unknown candidate modulators of GCase activity, which may facilitate the design of therapies for diseases with GCase dysfunction.
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The COVID-19 plague is hitting mankind. Several viruses, including SARS-CoV-1, MERS-CoV, EBOV, and SARS-CoV-2, use the endocytic machinery to enter the cell. Genomic variants in NPC1, which encodes for the endo-lysosomal Niemann-Pick type C1 protein, restricts the host-range of viruses in bats and susceptibility to infections in humans. Lack of NPC1 and its pharmacological suppression inhibits many viral infections including SARS-CoV-1 and Type I Feline Coronavirus Infection. Antiviral effects of NPC1-inhibiting drugs for COVID-19 treatment should be explored.
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COVID-19/fisiopatologia , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , SARS-CoV-2/fisiologia , Antivirais/uso terapêutico , COVID-19/virologia , Reposicionamento de Medicamentos , Humanos , Proteína C1 de Niemann-Pick , Índice de Gravidade de Doença , Internalização do Vírus , Tratamento Farmacológico da COVID-19RESUMO
The transcription factor EB (TFEB) has emerged as a master regulator of lysosomal biogenesis, exocytosis, and autophagy, promoting the clearance of substrates stored in cells. c-Abl is a tyrosine kinase that participates in cellular signaling in physiological and pathophysiological conditions. In this study, we explored the connection between c-Abl and TFEB. Here, we show that under pharmacological and genetic c-Abl inhibition, TFEB translocates into the nucleus promoting the expression of its target genes independently of its well-known regulator, mammalian target of rapamycin complex 1. Active c-Abl induces TFEB phosphorylation on tyrosine and the inhibition of this kinase promotes lysosomal biogenesis, autophagy, and exocytosis. c-Abl inhibition in Niemann-Pick type C (NPC) models, a neurodegenerative disease characterized by cholesterol accumulation in lysosomes, promotes a cholesterol-lowering effect in a TFEB-dependent manner. Thus, c-Abl is a TFEB regulator that mediates its tyrosine phosphorylation, and the inhibition of c-Abl activates TFEB promoting cholesterol clearance in NPC models.
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Niemann-Pick type C (NPC), a lysosomal storage disorder, is mainly caused by mutations in the NPC1 gene. Niemann-Pick type C patients and mice show intracellular cholesterol accumulation leading to hepatic failure with increased inflammatory response. The complement cascade, which belongs to the innate immunity response, recognizes danger signals from injured tissues. We aimed to determine whether there is activation of the complement system in the liver of the NPC mouse and to assess the relationship between C3 activation, a final component of the pathway, and NPC liver pathology. Niemann-Pick type C mice showed high levels of C3 staining in the liver which unexpectedly decreased with aging. Using an inducible NPC1 hepatocyte rescue mouse model, we restored NPC1 expression for a short time in young mice. We found C3 positive cells only in non-rescued cells, suggesting that C3 activation in NPC cells is reversible. Then, we studied the effect of C3 ablation on NPC liver damage at two postnatal time points, P56 and P72. Deletion of C3 reduced the presence of hepatic CD68-positive cells at postnatal day 56 and prevented the increase of transaminase levels in the blood of NPC mice. These positive effects were abrogated at P72, indicating that the complement cascade participates only during the early stages of liver damage in NPC mice, and that its inhibition may serve as a new potential therapeutic strategy for the disease.
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Complemento C3/metabolismo , Fígado/patologia , Doença de Niemann-Pick Tipo C/imunologia , Envelhecimento/patologia , Animais , Células Espumosas/metabolismo , Células Espumosas/patologia , Camundongos Endogâmicos C57BLRESUMO
A mechanistic understanding of the diverse clinical manifestations of Parkinson's disease (PD) and variable patient response to treatments is lacking. Genetically diverse PD model organisms can be used to map modifier genes and understand clinically relevant phenotypes of varying severity. This strategy can accelerate the pace of discoveries for precision medicine purposes.
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Doença de Parkinson/genética , Medicina de Precisão , Animais , Loci Gênicos , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , FenótipoRESUMO
Rare diseases (RDs) are a large number of diverse conditions with low individual prevalence, but collectively may affect up to 3.5-5.9% of the population. They have psychosocial and economic impact on patients and societies, and are a significant problem for healthcare systems, especially for countries with limited resources. In Chile, financial protection exists for 20 known RDs through different programs that cover diagnosis and treatments. Although beneficial for a number of conditions, most RD patients are left without a proper legal structure that guarantees a financial coverage, and in a vulnerable situation. In this review, we present and analyze the main challenges of the Chilean healthcare system and legislation on RDs, and other ambits of the RD ecosystem, including patient advocacy groups and research. Finally, we propose a set of policy recommendations that includes creating a patient registry, eliciting social preferences on health and financial coverage, improving access to clinical genetic services and therapies, promoting research on RDs and establishing a Latin-American cooperation network, all aimed at promoting equitable quality healthcare access for people living with RDs.
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Doenças Raras , Chile , Ecossistema , Política de Saúde , HumanosRESUMO
Niemannâ»Pick type C (NPC) disease is a rare neurovisceral cholesterol storage disorder that arises from loss of function mutations in the NPC1 or NPC2 genes. Soon after birth, some patients present with an aggressive hepatosplenomegaly and cholestatic signs. Histopathologically, the liver presents with large numbers of foam cells; however, their role in disease pathogenesis has not been explored in depth. Here, we studied the consequences of gadolinium chloride (GdCl3) treatment, a well-known Kupffer/foam cell inhibitor, at late stages of NPC liver disease and compared it with NPC1 genetic rescue in hepatocytes in vivo. GdCl3 treatment successfully blocked the endocytic capacity of hepatic Kupffer/foam measured by India ink endocytosis, decreased the levels CD68-A marker of Kupffer cells in the liver-and normalized the transaminase levels in serum of NPC mice to a similar extent to those obtained by genetic Npc1 rescue of liver cells. Gadolinium salts are widely used as magnetic resonance imaging (MRI) contrasts. This study opens the possibility of targeting foam cells with gadolinium or by other means for improving NPC liver disease. Synopsis: Gadolinium chloride can effectively rescue some parameters of liver dysfunction in NPC mice and its potential use in patients should be carefully evaluated.
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Gadolínio/farmacologia , Células de Kupffer/efeitos dos fármacos , Doença de Niemann-Pick Tipo C/tratamento farmacológico , Animais , Antígenos CD/genética , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/genética , Antígenos de Diferenciação Mielomonocítica/metabolismo , Endocitose , Gadolínio/uso terapêutico , Peptídeos e Proteínas de Sinalização Intracelular , Células de Kupffer/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Proteína C1 de Niemann-Pick , Proteínas/genética , Proteínas/metabolismoRESUMO
Common forms of Parkinson's disease have long been described as idiopathic, with no single penetrant genetic factor capable of influencing disease aetiology. Recent genetic studies indicate a clear association of variants within several lysosomal genes as risk factors for idiopathic Parkinson's disease. The emergence of novel variants suggest that the aetiology of idiopathic Parkinson's disease may be explained by the interaction of several partially penetrant mutations that, while seemingly complex, all appear to converge on cellular clearance pathways. These newly evolving data are consistent with mechanistic studies linking α-synuclein toxicity to lysosomal abnormalities, and indicate that idiopathic Parkinson's disease resembles features of Mendelian lysosomal storage disorders at a genetic and biochemical level. These findings offer novel pathways to exploit for the development of disease-altering therapies for idiopathic Parkinson's disease that target specific components of the lysosomal system.
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Doenças por Armazenamento dos Lisossomos/fisiopatologia , Doença de Parkinson/etiologia , Doença de Parkinson/fisiopatologia , Doença de Gaucher/genética , Doença de Gaucher/fisiopatologia , Humanos , Doenças por Armazenamento dos Lisossomos/genética , Lisossomos/genética , Lisossomos/fisiologia , Mitocôndrias/patologia , Doença de Parkinson/genética , Fatores de Risco , alfa-Sinucleína/metabolismoRESUMO
Reduced astrocytic gap junctional communication and enhanced hemichannel activity were recently shown to increase astroglial and neuronal vulnerability to neuroinflammation. Moreover, increasing evidence suggests that neuroinflammation plays a pivotal role in the development of Niemann-Pick type C (NPC) disease, an autosomal lethal neurodegenerative disorder that is mainly caused by mutations in the NPC1 gene. Therefore, we investigated whether the lack of NPC1 expression in murine astrocytes affects the functional state of gap junction channels and hemichannels. Cultured cortical astrocytes of NPC1 knock-out mice (Npc1â»/â») showed reduced intercellular communication via gap junctions and increased hemichannel activity. Similarly, astrocytes of newborn Npc1â»/â» hippocampal slices presented high hemichannel activity, which was completely abrogated by connexin 43 hemichannel blockers and was resistant to inhibitors of pannexin 1 hemichannels. Npc1â»/â» astrocytes also showed more intracellular Ca²âº signal oscillations mediated by functional connexin 43 hemichannels and P2Y1 receptors. Therefore, Npc1â»/â» astrocytes present features of connexin based channels compatible with those of reactive astrocytes and hemichannels might be a novel therapeutic target to reduce neuroinflammation in NPC disease.
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Astrócitos/metabolismo , Cálcio/metabolismo , Conexina 43/metabolismo , Junções Comunicantes/metabolismo , Doença de Niemann-Pick Tipo C/metabolismo , Proteínas/genética , Difosfato de Adenosina/análogos & derivados , Difosfato de Adenosina/farmacologia , Animais , Animais Recém-Nascidos , Anticorpos/farmacologia , Astrócitos/efeitos dos fármacos , Astrócitos/patologia , Sinalização do Cálcio , Comunicação Celular/efeitos dos fármacos , Células Cultivadas , Conexina 43/antagonistas & inibidores , Conexina 43/genética , Conexinas/genética , Conexinas/metabolismo , Modelos Animais de Doenças , Junções Comunicantes/efeitos dos fármacos , Deleção de Genes , Regulação da Expressão Gênica , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Proteína C1 de Niemann-Pick , Doença de Niemann-Pick Tipo C/patologia , Proteínas/metabolismo , Receptores Purinérgicos P2Y1/genética , Receptores Purinérgicos P2Y1/metabolismo , Técnicas de Cultura de TecidosRESUMO
Niemann-Pick type C (NPC) disease is an autosomal recessive neurovisceral lipid storage disorder. The affected genes are NPC1 and NPC2. Mutations in either gene lead to intracellular cholesterol accumulation. There are three forms of the disease, which are categorized based on the onset and severity of the disease: the infantile form, in which the liver and spleen are severely affected, the juvenile form, in which the liver and brain are affected, and the adult form, which affects the brain. In mice, a spontaneous mutation in the Npc1 gene originated in the BALB/c inbred strain mimics the juvenile form of the disease. To study the influence of genetic background on the expression of NPC disease in mice, we transferred the Npc1 mutation from the BALB/c to C57BL/6J inbred background. We found that C57BL/6J-Npc1(-/-) mice present with a much more aggressive form of the disease, including a shorter lifespan than BALB/c-Npc1(-/-) mice. Surprisingly, there was no difference in the amount of cholesterol in the brains of Npc1(-/-) mice of either mouse strain. However, Npc1(-/-) mice with the C57BL/6J genetic background showed striking spleen damage with a marked buildup of cholesterol and phospholipids at an early age, which correlated with large foamy cell clusters. In addition, C57BL/6J Npc1(-/-) mice presented red cell abnormalities and abundant ghost erythrocytes that correlated with a lower hemoglobin concentration. We also found abnormalities in white cells, such as cytoplasmic granulation and neutrophil hypersegmentation that included lymphopenia and atypias. In conclusion, Npc1 deficiency in the C57BL6/J background is associated with spleen, erythrocyte, and immune system abnormalities that lead to a reduced lifespan.