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1.
Int J Mol Sci ; 20(23)2019 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-31771289

RESUMO

Sphingolipidoses are inherited genetic diseases characterized by the accumulation of glycosphingolipids. Sphingolipidoses (SP), which usually involve the loss of sphingolipid hydrolase function, are of lysosomal origin, and represent an important group of rare diseases among lysosomal storage disorders. Initial treatments consisted of enzyme replacement therapy, but, in recent decades, various therapeutic approaches have been developed. However, these commonly used treatments for SP fail to be fully effective and do not penetrate the blood-brain barrier. New approaches, such as genome editing, have great potential for both the treatment and study of sphingolipidoses. Here, we review the most recent advances in the treatment and modelling of SP through the application of CRISPR-Cas9 genome editing. CRISPR-Cas9 is currently the most widely used method for genome editing. This technique is versatile; it can be used for altering the regulation of genes involved in sphingolipid degradation and synthesis pathways, interrogating gene function, generating knock out models, or knocking in mutations. CRISPR-Cas9 genome editing is being used as an approach to disease treatment, but more frequently it is utilized to create models of disease. New CRISPR-Cas9-based tools of gene editing with diminished off-targeting effects are evolving and seem to be more promising for the correction of individual mutations. Emerging Prime results and CRISPR-Cas9 difficulties are also discussed.


Assuntos
Sistemas CRISPR-Cas/genética , Edição de Genes/métodos , Esfingolipidoses/terapia , Animais , Modelos Animais de Doenças , Terapia de Reposição de Enzimas , Doença de Gaucher/genética , Doença de Gaucher/terapia , Humanos , Esfingolipidoses/genética , beta-Glucosidase/genética
2.
Glia ; 67(9): 1705-1718, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31140649

RESUMO

Sphingolipidoses are severe, mostly infantile lysosomal storage disorders (LSDs) caused by defective glycosphingolipid degradation. Two of these sphingolipidoses, Tay Sachs and Sandhoff diseases, are caused by ß-Hexosaminidase (HEXB) enzyme deficiency, resulting in ganglioside (GM2) accumulation and neuronal loss. The precise sequence of cellular events preceding, and leading to, neuropathology remains unclear, but likely involves inflammation and lysosomal accumulation of GM2 in multiple cell types. We aimed to determine the consequences of Hexb activity loss for different brain cell types using zebrafish. Hexb deficient zebrafish (hexb-/- ) showed lysosomal abnormalities already early in development both in radial glia, which are the neuronal and glial progenitors, and in microglia. Additionally, at 5 days postfertilization, hexb-/- zebrafish showed reduced locomotor activity. Although specific oligosaccharides accumulate in the adult brain, hexb-/- ) zebrafish are viable and apparently resistant to Hexb deficiency. In all, we identified cellular consequences of loss of Hexb enzyme activity during embryonic brain development, showing early effects on glia, which possibly underlie the behavioral aberrations. Hereby, we identified clues into the contribution of non-neuronal lysosomal abnormalities in LSDs affecting the brain and provide a tool to further study what underlies the relative resistance to Hexb deficiency in vivo.


Assuntos
Encéfalo/enzimologia , Encéfalo/crescimento & desenvolvimento , Lisossomos/enzimologia , Neuroglia/enzimologia , Cadeia beta da beta-Hexosaminidase/genética , Animais , Animais Geneticamente Modificados , Apoptose/fisiologia , Encéfalo/patologia , Modelos Animais de Doenças , Lisossomos/patologia , Atividade Motora/fisiologia , Neuroglia/patologia , Esfingolipidoses/enzimologia , Peixe-Zebra
3.
Dis Model Mech ; 12(5)2019 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-31036560

RESUMO

Glycosphingolipid (GSL) accumulation is implicated in the neuropathology of several lysosomal conditions, such as Krabbe disease, and may also contribute to neuronal and glial dysfunction in adult-onset conditions such as Parkinson's disease, Alzheimer's disease and multiple sclerosis. GSLs accumulate in cellular membranes and disrupt their structure; however, how membrane disruption leads to cellular dysfunction remains unknown. Using authentic cellular and animal models for Krabbe disease, we provide a mechanism explaining the inactivation of lipid raft (LR)-associated IGF-1-PI3K-Akt-mTORC2, a pathway of crucial importance for neuronal function and survival. We show that psychosine, the GSL that accumulates in Krabbe disease, leads to a dose-dependent LR-mediated inhibition of this pathway by uncoupling IGF-1 receptor phosphorylation from downstream Akt activation. This occurs by interfering with the recruitment of PI3K and mTORC2 to LRs. Akt inhibition can be reversed by sustained IGF-1 stimulation, but only during a time window before psychosine accumulation reaches a threshold level. Our study shows a previously unknown connection between LR-dependent regulation of mTORC2 activity at the cell surface and a genetic neurodegenerative disease. Our results show that LR disruption by psychosine desensitizes cells to extracellular growth factors by inhibiting signal transmission from the plasma membrane to intracellular compartments. This mechanism serves also as a mechanistic model to understand how alterations of the membrane architecture by the progressive accumulation of lipids undermines cell function, with potential implications in other genetic sphingolipidoses and adult neurodegenerative conditions. This article has an associated First Person interview with the first author of the paper.


Assuntos
Fator de Crescimento Insulin-Like I/metabolismo , Lisossomos/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Microdomínios da Membrana/metabolismo , Neurônios/patologia , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Esfingolipidoses/genética , Animais , Encéfalo/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Citosol/efeitos dos fármacos , Citosol/metabolismo , Regulação para Baixo/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Peptídeos e Proteínas de Sinalização Intercelular/farmacologia , Lisossomos/efeitos dos fármacos , Microdomínios da Membrana/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Modelos Biológicos , Neurônios/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Psicosina/farmacologia , Receptor IGF Tipo 1/metabolismo , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Transdução de Sinais/efeitos dos fármacos , Esfingolipidoses/metabolismo
4.
J Neurochem ; 148(5): 600-611, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-29959861

RESUMO

Ceramide, sphingomyelin, and glycosphingolipids (both neutral and acidic) are characterized by the presence in the lipid moiety of an aliphatic base known as sphingosine. Altogether, they are called sphingolipids and are particularly abundant in neuronal plasma membranes, where, via interactions with the other membrane lipids and membrane proteins, they play a specific role in modulating the cell signaling processes. The metabolic pathways determining the plasma membrane sphingolipid composition are thus the key point for functional changes of the cell properties. Unnatural changes of the neuronal properties are observed in sphingolipidoses, lysosomal storage diseases occurring when a lysosomal sphingolipid hydrolase is not working, leading to the accumulation of the substrate and to its distribution to all the cell membranes interacting with lysosomes. Moreover, secondary accumulation of sphingolipids is a common trait of other lysosomal storage diseases. This article is part of the Special Issue "Lysosomal Storage Disorders".


Assuntos
Doenças por Armazenamento dos Lisossomos/metabolismo , Degeneração Neural/metabolismo , Esfingolipidoses/metabolismo , Esfingolipídeos/metabolismo , Animais , Humanos , Doenças por Armazenamento dos Lisossomos/patologia , Lisossomos/metabolismo , Lisossomos/patologia , Degeneração Neural/patologia , Esfingolipidoses/patologia
5.
Int J Mol Sci ; 19(11)2018 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-30384423

RESUMO

In order to delineate a better approach to functional studies, we have selected 23 missense mutations distributed in different domains of two lysosomal enzymes, to be studied by in silico analysis. In silico analysis of mutations relies on computational modeling to predict their effects. Various computational platforms are currently available to check the probable causality of mutations encountered in patients at the protein and at the RNA levels. In this work we used four different platforms freely available online (Protein Variation Effect Analyzer- PROVEAN, PolyPhen-2, Swiss-model Expert Protein Analysis System-ExPASy, and SNAP2) to check amino acid substitutions and their effect at the protein level. The existence of functional studies, regarding the amino acid substitutions, led to the selection of the distinct protein mutants. Functional data were used to compare the results obtained with different bioinformatics tools. With the advent of next-generation sequencing, it is not feasible to carry out functional tests in all the variants detected. In silico analysis seems to be useful for the delineation of which mutants are worth studying through functional studies. Therefore, prediction of the mutation impact at the protein level, applying computational analysis, confers the means to rapidly provide a prognosis value to genotyping results, making it potentially valuable for patient care as well as research purposes. The present work points to the need to carry out functional studies in mutations that might look neutral. Moreover, it should be noted that single nucleotide polymorphisms (SNPs), occurring in coding and non-coding regions, may lead to RNA alterations and should be systematically verified. Functional studies can gain from a preliminary multi-step approach, such as the one proposed here.


Assuntos
Simulação por Computador , Glucosilceramidase , Modelos Biológicos , Mutação de Sentido Incorreto , Esfingolipidoses , alfa-Galactosidase , Glucosilceramidase/genética , Glucosilceramidase/metabolismo , Humanos , Esfingolipidoses/enzimologia , Esfingolipidoses/genética , alfa-Galactosidase/genética , alfa-Galactosidase/metabolismo
6.
Adv Biol Regul ; 70: 82-88, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30205942

RESUMO

Niemann-Pick type C (NPC) disease is a lysosomal storage disorder resulting from mutations in either the NPC1 (95%) or NPC2 (5%) genes. NPC typically presents in childhood with visceral lipid accumulation and complex progressive neurodegeneration characterized by cerebellar ataxia, dysphagia, and dementia, resulting in a shortened lifespan. While cholesterol is widely acknowledged as the principal storage lipid in NPC, multiple species of sphingolipids accumulate as well. This accumulation of sphingolipids led to the initial assumption that NPC disease was caused by a deficiency in a sphingolipid catabolism enzyme, similar to sphingomyelinase deficiencies with which it shares a family name. It took about half a century to determine that NPC was in fact caused by a cholesterol trafficking defect, and still as we approach a century after the initial identification of the disease, the mechanisms by which sphingolipids accumulate remain poorly understood. Here we focus on the defects of sphingolipid catabolism in the endolysosomal compartment and how they contribute to the biology and pathology observed in NPC disease. This review highlights the need for further work on understanding and possibly developing treatments to correct the accumulation of sphingolipids in addition to cholesterol in this currently untreatable disease.


Assuntos
Doença de Niemann-Pick Tipo C/metabolismo , Animais , Humanos , Lisossomos/metabolismo , Proteína C1 de Niemann-Pick/genética , Proteína C1 de Niemann-Pick/metabolismo , Doença de Niemann-Pick Tipo C/genética , Esfingolipidoses/genética , Esfingolipidoses/metabolismo , Esfingolipídeos/metabolismo
7.
Essays Biochem ; 61(6): 733-749, 2017 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-29233882

RESUMO

The lysosome plays a pivotal role between catabolic and anabolic processes as the nexus for signalling pathways responsive to a variety of factors, such as growth, nutrient availability, energetic status and cellular stressors. Lysosomes are also the terminal degradative organelles for autophagy through which macromolecules and damaged cellular components and organelles are degraded. Autophagy acts as a cellular homeostatic pathway that is essential for organismal physiology. Decline in autophagy during ageing or in many diseases, including late-onset forms of neurodegeneration is considered a major contributing factor to the pathology. Multiple lines of evidence indicate that impairment in autophagy is also a central mechanism underlying several lysosomal storage disorders (LSDs). LSDs are a class of rare, inherited disorders whose histopathological hallmark is the accumulation of undegraded materials in the lysosomes due to abnormal lysosomal function. Inefficient degradative capability of the lysosomes has negative impact on the flux through the autophagic pathway, and therefore dysregulated autophagy in LSDs is emerging as a relevant disease mechanism. Pathology in the LSDs is generally early-onset, severe and life-limiting but current therapies are limited or absent; recognizing common autophagy defects in the LSDs raises new possibilities for therapy. In this review, we describe the mechanisms by which LSDs occur, focusing on perturbations in the autophagy pathway and present the latest data supporting the development of novel therapeutic approaches related to the modulation of autophagy.


Assuntos
Autofagia/fisiologia , Doenças por Armazenamento dos Lisossomos/metabolismo , Animais , Autofagia/genética , Humanos , Doenças por Armazenamento dos Lisossomos/genética , Lisossomos/metabolismo , Esfingolipidoses/metabolismo
8.
Future Med Chem ; 9(14): 1687-1700, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28857617

RESUMO

Sphingolipidoses are genetically inherited diseases in which genetic mutations lead to functional deficiencies in the enzymes needed for lysosomal degradation of sphingolipid substrates. As a consequence, nondegradable lipids enrich in the lysosomes and lead to fatal pathological phenotypes in affected individuals. In this review, different drug-based treatment strategies including enzyme replacement therapy and substrate reduction therapy are discussed. A special focus is on the concept of pharmacological chaperones, one of which recently acquired clinical approval within the EU. On the basis of the different limitations for each approach, possible future directions of research are discussed.


Assuntos
Terapia Enzimática , Esfingolipidoses/tratamento farmacológico , Terapia de Reposição de Enzimas , Enzimas/genética , Enzimas/metabolismo , Doença de Fabry/tratamento farmacológico , Doença de Gaucher/tratamento farmacológico , Glucosilceramidase/genética , Glucosilceramidase/metabolismo , Glucosilceramidase/uso terapêutico , Humanos , Lisossomos/metabolismo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/uso terapêutico , Esfingolipidoses/genética , Esfingolipidoses/patologia , Esfingolipídeos/metabolismo , alfa-Galactosidase/genética , alfa-Galactosidase/metabolismo , alfa-Galactosidase/uso terapêutico
9.
Dis Model Mech ; 10(6): 737-750, 2017 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-28389479

RESUMO

Sphingolipidoses are inherited diseases belonging to the class of lysosomal storage diseases (LSDs), which are characterized by the accumulation of indigestible material in the lysosome caused by specific defects in the lysosomal degradation machinery. While some LSDs can be efficiently treated by enzyme replacement therapy (ERT), this is not possible if the nervous system is affected due to the presence of the blood-brain barrier. Sphingolipidoses in particular often present as severe, untreatable forms of LSDs with massive sphingolipid and membrane accumulation in lysosomes, neurodegeneration and very short life expectancy. The digestion of intralumenal membranes within lysosomes is facilitated by lysosomal sphingolipid activator proteins (saposins), which are cleaved from a prosaposin precursor. Prosaposin mutations cause some of the severest forms of sphingolipidoses, and are associated with perinatal lethality in mice, hampering studies on disease progression. We identify the Drosophila prosaposin orthologue Saposin-related (Sap-r) as a key regulator of lysosomal lipid homeostasis in the fly. Its mutation leads to a typical spingolipidosis phenotype with an enlarged endolysosomal compartment and sphingolipid accumulation as shown by mass spectrometry and thin layer chromatography. Sap-r mutants show reduced viability with ∼50% survival to adulthood, allowing us to study progressive neurodegeneration and analyze their lipid profile in young and aged flies. Additionally, we observe a defect in sterol homeostasis with local sterol depletion at the plasma membrane. Furthermore, we find that autophagy is increased, resulting in the accumulation of mitochondria in lysosomes, concomitant with increased oxidative stress. Together, we establish Drosophila Sap-r mutants as a lysosomal storage disease model suitable for studying the age-dependent progression of lysosomal dysfunction associated with lipid accumulation and the resulting pathological signaling events.


Assuntos
Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Doenças por Armazenamento dos Lisossomos/genética , Mutação/genética , Saposinas/genética , Esfingolipidoses/genética , Ácidos/metabolismo , Animais , Membrana Celular/metabolismo , Modelos Animais de Doenças , Proteínas de Drosophila/metabolismo , Doenças por Armazenamento dos Lisossomos/fisiopatologia , Lisossomos/metabolismo , Lisossomos/ultraestrutura , Atividade Motora , Degeneração Neural/patologia , Degeneração Neural/fisiopatologia , Estresse Oxidativo , Fosfolipídeos/metabolismo , Transporte Proteico , Homologia de Sequência de Aminoácidos , Esfingolipidoses/fisiopatologia , Esfingolipídeos/metabolismo , Esteróis/metabolismo , Frações Subcelulares/metabolismo
10.
Curr Cardiol Rep ; 19(3): 26, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28251514

RESUMO

PURPOSE OF REVIEW: The aim of this study is to review the published human-induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) models of cardiac storage disorders and to evaluate the limitations and future applications of this technology. RECENT FINDINGS: Several cardiac storage disorders (CSDs) have been modeled using patient-specific hiPSC-CMs, including Anderson-Fabry disease, Danon disease, and Pompe disease. These models have shown that patient-specific hiPSC-CMs faithfully recapitulate key phenotypic features of CSDs and respond predictably to pharmacologic manipulation. hiPSC-CMs generated from patients with CSDs are representative models of the patient disease state and can be used as an in vitro system for the study of human cardiomyocytes. While these models suffer from several limitations, they are likely to play an important role in future mechanistic studies of cardiac storage disorders and the development of targeted therapeutics for these diseases.


Assuntos
Cardiopatias/patologia , Células-Tronco Pluripotentes Induzidas/patologia , Erros Inatos do Metabolismo/patologia , Miócitos Cardíacos/patologia , Doença de Fabry , Doença de Depósito de Glicogênio Tipo II/patologia , Doença de Depósito de Glicogênio Tipo IIb/patologia , Humanos , Mucopolissacaridoses/patologia , Esfingolipidoses/patologia
11.
Clin Chim Acta ; 466: 178-184, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28089753

RESUMO

Free sphingoid bases (lysosphingolipids) of primary storage sphingolipids are increased in tissues and plasma of several sphingolipidoses. As shown earlier by us, sphingoid bases can be accurately quantified using UPLC-ESI-MS/MS, particularly in combination with identical 13C-encoded internal standards. The feasibility of simultaneous quantitation of sphingoid bases in plasma specimens spiked with a mixture of such standards is here described. The sensitivity and linearity of detection is excellent for all examined sphingoid bases (sphingosine, sphinganine, hexosyl-sphingosine (glucosylsphingosine), hexosyl2-sphingosine (lactosylsphingosine), hexosyl3-sphingosine (globotriaosylsphingosine), phosphorylcholine-sphingosine) in the relevant concentration range and the measurements show very acceptable intra- and inter-assay variation (<10% average). Plasma samples of a series of male and female Gaucher Disease and Fabry Disease patients were analyzed with the multiplex assay. The obtained data compare well to those earlier determined for plasma globotriaosylsphingosine and glucosylsphingosine in GD and FD patients. The same approach can be also applied to measure sphingolipids in the same sample. Following extraction of sphingolipids from the same sample these can be converted to sphingoid bases by microwave exposure and subsequently quantified using 13C-encoded internal standards.


Assuntos
Esfingolipidoses/sangue , Esfingolipídeos/análise , Espectrometria de Massas em Tandem/métodos , Isótopos de Carbono/normas , Cromatografia Líquida de Alta Pressão , Doença de Fabry/sangue , Feminino , Doença de Gaucher/sangue , Humanos , Masculino , Padrões de Referência , Esfingolipídeos/sangue
12.
Clin Chem Lab Med ; 55(3): 403-414, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-27533120

RESUMO

BACKGROUND: Lysosphingolipids (LysoSLs) are derivatives of sphingolipids which have lost the amide-linked acyl chain. More recently, LysoSLs have been identified as storage compounds in several sphingolipidoses, including Gaucher, Fabry and Niemann-Pick diseases. To date, different methods have been developed to measure each individual lysosphingolipid in plasma. This report describes a rapid liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) assay for simultaneous quantification of several LysoSLs in plasma. METHODS: We analyzed the following compounds: hexosylsphingosine (HexSph), globotriaosylsphingosine (LysoGb3), lysosphingomyelin (LysoSM) and lysosphingomyelin-509 (LysoSM-509). The sample preparation requires only 100 µL of plasma and consists of an extraction with a mixture of MeOH/acetone/H2O (45:45:10, v/v). RESULTS: The method validation showed high sensitivity, an excellent accuracy and precision. Reference ranges were determined in healthy adult and pediatric population. The results demonstrate that the LC-MS/MS method can quantify different LysoSLs and can be used to identify patients with Fabry (LysoGb3), Gaucher and Krabbe (HexSph) diseases, prosaposine deficiency (LysoGb3 and HexSph), and Niemann-Pick disease types A/B and C (LysoSM and LysoSM-509). CONCLUSIONS: This LC-MS/MS method allows a rapid and simultaneous quantification of LysoSLs and is useful as a biochemical diagnostic tool for sphingolipidoses.


Assuntos
Biomarcadores/sangue , Cromatografia Líquida/métodos , Esfingolipidoses/diagnóstico , Esfingolipídeos/sangue , Espectrometria de Massas em Tandem/métodos , Adolescente , Adulto , Idoso , Estudos de Casos e Controles , Criança , Pré-Escolar , Humanos , Lactente , Recém-Nascido , Pessoa de Meia-Idade , Valores de Referência , Reprodutibilidade dos Testes , Esfingolipidoses/sangue , Adulto Jovem
13.
Adv Clin Chem ; 77: 177-219, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27717417

RESUMO

In recent years, mass spectrometry (MS) has become the dominant technology in lipidomic analysis. It is widely used in diagnosis and research of lipid metabolism disorders including those characterized by impairment of lysosomal functions and storage of nondegraded-degraded substrates. These rare diseases, which include sphingolipidoses, have severe and often fatal clinical consequences. Modern MS methods have contributed significantly to achieve a definitive diagnosis, which is essential in clinical practice to begin properly targeted patient care. Here we summarize MS and tandem MS methods used for qualitative and quantitative analysis of sphingolipids (SL) relative to the diagnostic process for sphingolipidoses and studies focusing on alterations in cell functions due to these disorders. This review covers the following topics: Tandem MS is sensitive and robust in determining the composition of sphingolipid classes in various biological materials. Its ability to establish SL metabolomic profiles using MS bench-top analyzers, significantly benefits the first stages of a diagnosis as well as metabolic studies of these disorders. It can thus contribute to a better understanding of the biological significance of SL.


Assuntos
Esfingolipidoses/diagnóstico , Esfingolipídeos/análise , Espectrometria de Massas em Tandem/métodos , Humanos , Esfingolipídeos/química , Esfingolipídeos/fisiologia
14.
Orphanet J Rare Dis ; 11(1): 126, 2016 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-27629047

RESUMO

BACKGROUND: Inborn errors of metabolism (IEMs) are individually rare; however, they are collectively common. More than 600 human diseases caused by inborn errors of metabolism are now recognized, and this number is constantly increasing as new concepts and techniques become available for identifying biochemical phenotypes. The aim of this study was to determine the type and distribution of IEMs in patients presenting to a tertiary care center in Saudi Arabia. METHOD: We conducted a retrospective review of children diagnosed with IEMs presenting to the Pediatric Department of King Abdulaziz Medical City in Riyadh, Saudi Arabia over a 13-year period. RESULTS: Over the 13- year period of this retrospective cohort, the total number of live births reached 110,601. A total of 187 patients were diagnosed with IEMs, representing a incidence of 169 in 100,000 births (1:591). Of these, 121 patients (64.7 %) were identified to have small molecule diseases and 66 (35.3 %) to have large molecule diseases. Organic acidemias were the most common small molecule IEMs, while lysosomal storage disorders (LSD) were the most common large molecule diseases. Sphingolipidosis were the most common LSD. CONCLUSION: Our study confirms the previous results of the high rate of IEMs in Saudi Arabia and urges the health care strategists in the country to devise a long-term strategic plan, including an IEM national registry and a high school carrier screening program, for the prevention of such disorders. In addition, we identified 43 novel mutations that were not described previously, which will help in the molecular diagnosis of these disorders.


Assuntos
Erros Inatos do Metabolismo/epidemiologia , Feminino , Humanos , Incidência , Doenças por Armazenamento dos Lisossomos/epidemiologia , Doenças por Armazenamento dos Lisossomos/genética , Masculino , Erros Inatos do Metabolismo/genética , Mutação/genética , Estudos Retrospectivos , Arábia Saudita/epidemiologia , Esfingolipidoses/epidemiologia , Esfingolipidoses/genética
15.
Sci Transl Med ; 8(355): 355ra118, 2016 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-27605553

RESUMO

Lysosomal storage diseases (LSDs) often manifest with severe systemic and central nervous system (CNS) symptoms. The existing treatment options are limited and have no or only modest efficacy against neurological manifestations of disease. We demonstrate that recombinant human heat shock protein 70 (HSP70) improves the binding of several sphingolipid-degrading enzymes to their essential cofactor bis(monoacyl)glycerophosphate in vitro. HSP70 treatment reversed lysosomal pathology in primary fibroblasts from 14 patients with eight different LSDs. HSP70 penetrated effectively into murine tissues including the CNS and inhibited glycosphingolipid accumulation in murine models of Fabry disease (Gla(-/-)), Sandhoff disease (Hexb(-/-)), and Niemann-Pick disease type C (Npc1(-/-)) and attenuated a wide spectrum of disease-associated neurological symptoms in Hexb(-/-) and Npc1(-/-) mice. Oral administration of arimoclomol, a small-molecule coinducer of HSPs that is currently in clinical trials for Niemann-Pick disease type C (NPC), recapitulated the effects of recombinant human HSP70, suggesting that heat shock protein-based therapies merit clinical evaluation for treating LSDs.


Assuntos
Proteínas de Choque Térmico/uso terapêutico , Esfingolipidoses/tratamento farmacológico , Administração Intravenosa , Animais , Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/patologia , Proteínas Morfogenéticas Ósseas/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Doença de Fabry/tratamento farmacológico , Doença de Fabry/patologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/patologia , Glicoesfingolipídeos/metabolismo , Proteínas de Choque Térmico/farmacologia , Humanos , Hidroxilaminas/farmacologia , Hidroxilaminas/uso terapêutico , Injeções Intraperitoneais , Peptídeos e Proteínas de Sinalização Intracelular , Lisossomos/efeitos dos fármacos , Lisossomos/patologia , Doença de Niemann-Pick Tipo C/tratamento farmacológico , Proteínas/metabolismo , Proteínas Recombinantes/farmacocinética , Proteínas Recombinantes/farmacologia , Proteínas Recombinantes/uso terapêutico , Esfingolipidoses/patologia , Distribuição Tecidual
16.
J Neurosci Res ; 94(11): 1019-24, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27638586

RESUMO

Sphingolipidoses arise from inherited loss of function of key enzymes regulating the sphingolipid (SL) metabolism and the accumulation of large quantities of these lipids in affected cells. Most frequently, toxicity is manifested in the nervous system, where survival and function of neurons and glial cells are most affected. Although detailed information is available on neuroglial alterations during terminal stages of the disease, the initial pathogenic mechanisms triggering neuropathology are largely unclear. Because they are key components of biological membranes, changes in the local concentration of SLs are likely to impact the organization of membrane domains and functions. This Commentary proposes that SL toxicity involves initial defects in the integrity of lipid domains, membrane fluidity, and membrane bending, leading to membrane deformation and deregulation of cell signaling and function. Understanding how SLs alter membrane architecture may provide breakthroughs for more efficient treatment of sphingolipidoses. © 2016 Wiley Periodicals, Inc.


Assuntos
Fluidez de Membrana/fisiologia , Lipídeos de Membrana/genética , Esfingolipidoses/genética , Esfingolipidoses/patologia , Animais , Humanos , Lipídeos de Membrana/deficiência
17.
J Neurosci Res ; 94(11): 1031-6, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27638588

RESUMO

The presence of life-threatening neurological symptoms in more than two-thirds of lysosomal storage diseases (LSDs) underscores how vulnerable the nervous system is to lysosomal failure. Neurological dysfunction in LSDs has historically been attributed to the disruption of neuronal and glial homeostasis resulting from the progressive jamming of the endosomal/lysosomal pathway. In neurons, a dysfunctional endosomal-lysosomal system can elicit dire consequences. Given that neurons are largely postmitotic after birth, one can clearly understand that the inability of these cells to proliferate obliterates any possibility of diluting stored lysosomal material by means of cellular division. At its most advanced stage, this situation constitutes a terminal factor in neuronal life, resulting in cell death. However, synaptic deficits in the absence of classical neuronal cell death appear to be common features during the early stages in many LSDs, particularly sphingolipidoses. In essence, failure of synapses to convey their messages, even without major structural damage to the neuronal bodies, is a form of physiological death. This concept of dying-back neuropathology is highly relevant not only for understanding the dynamics of the neurological decline in these diseases, but, more importantly; it might also constitute an important target for molecular therapies to protect perhaps the "Achilles" point in the entire physiological architecture of the brain, thus avoiding an irreversible journey to neuronal demise. © 2016 Wiley Periodicals, Inc.


Assuntos
Sistema Nervoso/patologia , Neurônios/patologia , Esfingolipidoses/patologia , Sinapses/fisiologia , Animais , Humanos , Modelos Neurológicos
18.
J Neurosci Res ; 94(11): 1042-8, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27638590

RESUMO

Sphingolipidoses are a class of inherited diseases that result from the toxic accumulation of undigested sphingolipids in lysosomes and other cellular membranes. Sphingolipids are particularly enriched in cells of the nervous system, and their excessive accumulation during disease has a significant impact on the nervous system. Neuronal dysfunction followed by neurological compromise is a common feature in many of these diseases; however, the underlying mechanisms that cause vulnerability of neurons are not fully understood. The plasma membrane plays a critical role in regulating cellular survival pathways, and its dysfunction has been implicated in neuronal failure in various adult-onset neuropathies. In the context of sphingolipidoses, we hypothesize that gradual accumulation of undigested lipids in plasma membranes causes local disruptions in lipid raft domains, leading to deregulation of multiple signaling pathways important for neuronal survival and function. We propose that defects in downstream signaling as a result of membrane dysfunction are common mechanisms underlying neuronal vulnerability in sphingolipid storage disorders with neurological compromise. © 2016 Wiley Periodicals, Inc.


Assuntos
Membrana Celular/metabolismo , Sistema Nervoso/patologia , Neurônios/patologia , Esfingolipidoses/patologia , Esfingolipídeos/metabolismo , Animais , Membrana Celular/patologia , Humanos , Esfingolipídeos/toxicidade
19.
J Neurosci Res ; 94(11): 1333-40, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27638615

RESUMO

The discovery that most cells produce extracellular vesicles (EVs) and release them in the extracellular milieu has spurred the idea that these membranous cargoes spread pathogenic mechanisms. In the brain, EVs may have multifold and important physiological functions, from deregulating synaptic activity to promoting demyelination to changes in microglial activity. The finding that small EVs (exosomes) contain α-synuclein and ß-amyloid, among other pathogenic proteins, is an example of this notion, underscoring their potential role in the brains of patients with Parkinson's and Alzheimer's diseases. Given that they are membranous vesicles, we speculate that EVs also have an intrinsic capacity to incorporate sphingolipids. In conditions under which these lipids are elevated to toxic levels, such as in Krabbe's disease and metachromatic leukodystrophy, EVs may contribute to spread disease from sick to healthy cells. In this essay, we discuss a working hypothesis that brain cells in sphingolipidoses clear some of the accumulated lipid material to attempt restoring cell homeostasis via EV secretion. We hypothesize that secreted sphingolipid-loaded EVs shuttle pathogenic lipids to cells that are not intrinsically affected, contributing to establishing non-cell-autonomous defects. © 2016 Wiley Periodicals, Inc.


Assuntos
Transporte Biológico/fisiologia , Encéfalo/citologia , Comunicação Celular/fisiologia , Vesículas Extracelulares/metabolismo , Esfingolipídeos/metabolismo , Animais , Humanos , Modelos Biológicos , Esfingolipidoses/patologia , Esfingolipídeos/toxicidade
20.
Biochimie ; 130: 146-151, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27157270

RESUMO

Glycosphingolipids and sphingolipids of cellular plasma membranes (PMs) reach luminal intra-lysosomal vesicles (LVs) for degradation mainly by pathways of endocytosis. After a sorting and maturation process (e.g. degradation of sphingomyelin (SM) and secretion of cholesterol), sphingolipids of the LVs are digested by soluble enzymes with the help of activator (lipid binding and transfer) proteins. Inherited defects of lipid-cleaving enzymes and lipid binding and transfer proteins cause manifold and fatal, often neurodegenerative diseases. The review summarizes recent findings on the regulation of sphingolipid catabolism and cholesterol secretion from the endosomal compartment by lipid modifiers, an essential stimulation by anionic membrane lipids and an inhibition of crucial steps by cholesterol and SM. Reconstitution experiments in the presence of all proteins needed, hydrolase and activator proteins, reveal an up to 10-fold increase of ganglioside catabolism just by the incorporation of anionic lipids into the ganglioside carrying membranes, whereas an additional incorporation of cholesterol inhibits GM2 catabolism substantially. It is suggested that lipid and other low molecular modifiers affect the genotype-phenotype relationship observed in patients with lysosomal diseases.


Assuntos
Lisossomos/metabolismo , Lipídeos de Membrana/metabolismo , Proteínas Ativadoras de Esfingolipídeos/metabolismo , Esfingolipidoses/metabolismo , Esfingolipídeos/metabolismo , Colesterol/metabolismo , Endossomos/metabolismo , Humanos , Modelos Biológicos
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