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1.
Am J Med Genet A ; 182(1): 64-70, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31729175

RESUMO

Infantile onset cardiomyopathies are highly heterogeneous with several phenocopies compared with adult cardiomyopathies. Multidisciplinary management is essential in determining the underlying etiology in children's cardiomyopathy. Elevated urinary excretion of 3-methylglutaconic acid (3-MGA) is a useful tool in identifying the etiology in some metabolic cardiomyopathy. Here, we report the delayed appearance of 3-MGA-uria, between 6 and 18 months in three patients (out of 100 childhood onset cardiomyopathy) with neonatal onset cardiomyopathy, secondary to TMEM70 mutations and TAZ mutations (Barth syndrome), in whom extensive metabolic investigations, performed in the first weeks of life, did not display 3-MGA-uria. Serial retrospective evaluations showed full characteristic features of TMEM70 and TAZ mutations (Barth syndrome) in these three patients, including a clearly abnormal monolysocardiolipin/cardiolipin ratio in the two Barth syndrome patients. Serially repeated metabolic investigations finally discovered the 3-MGA-uria biomarker in all three patients between the age of 6 and 18 months. Our observation provides novel insights into the temporal appearance of 3-MGA-uria in TMEM70 and TAZ mutations (Barth syndrome) and focus the importance of multidisciplinary management and careful evaluation of family history and red flag signs for phenocopies in infantile onset cardiomyopathies.

2.
J Inherit Metab Dis ; 2019 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-31845336

RESUMO

Secondary carnitine deficiency is commonly observed in inherited metabolic diseases characterised by the accumulation of acylcarnitines such as mitochondrial fatty acid oxidation (FAO) disorders. It is currently unclear if carnitine deficiency and/or acylcarnitine accumulation play a role in the pathophysiology of FAO disorders. The long-chain acyl-CoA dehydrogenase (LCAD) KO mouse is a model for long-chain FAO disorders and is characterised by decreased levels of tissue and plasma free carnitine. Tissue levels of carnitine are controlled by SLC22A5, the plasmalemmal carnitine transporter. Here, we have further decreased carnitine availability in the LCAD KO mouse through a genetic intervention by introducing one defective Slc22a5 allele (jvs). Slc22a5 haploinsufficiency decreased free carnitine levels in liver, kidney, and heart of LCAD KO animals. The resulting decrease in the tissue long-chain acylcarnitines levels had a similar magnitude as the decrease in free carnitine. Levels of cardiac deoxycarnitine, a carnitine biosynthesis intermediate, were elevated due to Slc22a5 haploinsufficiency in LCAD KO mice. A similar increase in heart and muscle deoxycarnitine was observed in an independent experiment using Slc22a5jvs/jvs mice. Cardiac hypertrophy, fasting-induced hypoglycemia and increased liver weight, the major phenotypes of the LCAD KO mouse, were not affected by Slc22a5 haploinsufficiency. This may suggest that secondary carnitine deficiency does not play a major role in the pathophysiology of these phenotypes. Similarly, our data do not support a major role for toxicity of long-chain acylcarnitines in the phenotype of the LCAD KO mouse.

3.
J Appl Genet ; 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31628608

RESUMO

Zellweger spectrum disorders (ZSD) constitute a group of rare autosomal recessive disorders characterized by a defect in peroxisome biogenesis due to mutations in one of 13 PEX genes. The broad clinical heterogeneity especially in late-onset presenting patients and a mild phenotype complicates and delays the diagnostic process. Here, we report a case of mild ZSD, due to novel PEX1 variants. The patient presented with an early hearing loss, bilateral cataracts, and leukodystrophy on magnetic resonance (MR) images. Normal results of serum very-long-chain fatty acids (VLCFA) and phytanic acid were found. Molecular diagnostics were performed to uncover the etiology of the clinical phenotype. Using whole exome sequencing, there have been found two variants in the PEX1 gene-c.3450T>A (p.Cys1150*) and c.1769T>C (p.Leu590Pro). VLCFA measurement in skin fibroblasts and C26:0-lysoPC in dried blood spot therefore was performed. Both results were in line with the diagnosis of ZSD. To conclude, normal results of routine serum VLCFA and branched-chain fatty acid measurement do not exclude mild forms of ZSD. The investigation of C26:0-lysoPC should be included in the diagnostic work-up in patients with cataract, hearing loss, and leukodystrophy on MR images suspected to suffer from ZSD.

4.
Brain ; 142(11): 3382-3397, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31637422

RESUMO

CTP:phosphoethanolamine cytidylyltransferase (ET), encoded by PCYT2, is the rate-limiting enzyme for phosphatidylethanolamine synthesis via the CDP-ethanolamine pathway. Phosphatidylethanolamine is one of the most abundant membrane lipids and is particularly enriched in the brain. We identified five individuals with biallelic PCYT2 variants clinically characterized by global developmental delay with regression, spastic para- or tetraparesis, epilepsy and progressive cerebral and cerebellar atrophy. Using patient fibroblasts we demonstrated that these variants are hypomorphic, result in altered but residual ET protein levels and concomitant reduced enzyme activity without affecting mRNA levels. The significantly better survival of hypomorphic CRISPR-Cas9 generated pcyt2 zebrafish knockout compared to a complete knockout, in conjunction with previously described data on the Pcyt2 mouse model, indicates that complete loss of ET function may be incompatible with life in vertebrates. Lipidomic analysis revealed profound lipid abnormalities in patient fibroblasts impacting both neutral etherlipid and etherphospholipid metabolism. Plasma lipidomics studies also identified changes in etherlipids that have the potential to be used as biomarkers for ET deficiency. In conclusion, our data establish PCYT2 as a disease gene for a new complex hereditary spastic paraplegia and confirm that etherlipid homeostasis is important for the development and function of the brain.

5.
Front Neurol ; 10: 762, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31379716

RESUMO

Inborn errors of metabolism (IEMs) are rare group of genetic disorders comprising of more than 1,000 different types. Around 200 of IEMs are potentially treatable through diet, pharmacological and other therapies, if diagnosed earlier in life. IEMs can be diagnosed early through newborn screening (NBS) programs, which are in place in most of the developed countries. However, establishing a NBS in a developing country is a challenging task due to scarcity of disease related data, large population size, poor economy, and burden of other common disorders. Since, not enough data is available for the prevalence of IEMs in Pakistan; therefore, in this study, we set out to find the prevalence of various treatable IEMs in a cohort of intellectually disabled patients suspected for IEMs, which will help us to initiate a NBS program for the most frequent IEMs in Pakistan. Therefore, a total of 429 intellectually disabled (IQ <70) patient samples were collected from Pakistan. A subset of 113 patient samples was selected based on the clinical information for the detailed biochemical screening. Advance analytical techniques like, Amino Acid Analyzer, GC-MS, UHPLC-MS, and MS/MS were used to screen for different treatable IEMs like aminoacidopathies, fatty acid ß-oxidation disorders and mucopolysaccharidoses (MPS) etc. A total of 14 patients were diagnosed with an IEM i.e., 9 with homocystinuria, 2 with MPS, 2 with Guanidinoacetate methyltransferase (GAMT) deficiency and 1 with sitosterolemia. These IEMs are found frequent in the collected patient samples from Pakistan. Thus, present study can help to take an initiative step to start a NBS program in Pakistan, especially for the homocystinuria having highest incidence among aminoacidopathies in the studied patients, and which is amenable to treatment. This endeavor will pave the way for a healthier life of affected patients and will lessen the burden on their families and society.

6.
JCI Insight ; 4(14)2019 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-31341105

RESUMO

Mitochondrial dysfunction characterizes many rare and common age-associated diseases. The biochemical consequences, underlying clinical manifestations, and potential therapeutic targets, remain to be better understood. We tested the hypothesis that lipid dyshomeostasis in mitochondrial disorders goes beyond mitochondrial fatty acid ß-oxidation, particularly in liver. This was achieved using comprehensive untargeted and targeted lipidomics in a case-control cohort of patients with Leigh syndrome French-Canadian variant (LSFC), a mitochondrial disease caused by mutations in LRPPRC, and in mice harboring liver-specific inactivation of Lrpprc (H-Lrpprc-/-). We discovered a plasma lipid signature discriminating LSFC patients from controls encompassing lower levels of plasmalogens and conjugated bile acids, which suggest perturbations in peroxisomal lipid metabolism. This premise was reinforced in H-Lrpprc-/- mice, which compared with littermates recapitulated a similar, albeit stronger peroxisomal metabolic signature in plasma and liver including elevated levels of very-long-chain acylcarnitines. These mice also presented higher transcript levels for hepatic markers of peroxisome proliferation in addition to lipid remodeling reminiscent of nonalcoholic fatty liver diseases. Our study underscores the value of lipidomics to unveil unexpected mechanisms underlying lipid dyshomeostasis ensuing from mitochondrial dysfunction herein implying peroxisomes and liver, which likely contribute to the pathophysiology of LSFC, but also other rare and common mitochondrial diseases.

7.
Hum Mutat ; 40(10): 1899-1904, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31187905

RESUMO

Primary carnitine deficiency is caused by a defect in the active cellular uptake of carnitine by Na+ -dependent organic cation transporter novel 2 (OCTN2). Genetic diagnostic yield for this metabolic disorder has been relatively low, suggesting that disease-causing variants are missed. We Sanger sequenced the 5' untranslated region (UTR) of SLC22A5 in individuals with possible primary carnitine deficiency in whom no or only one mutant allele had been found. We identified a novel 5'-UTR c.-149G>A variant which we characterized by expression studies with reporter constructs in HeLa cells and by carnitine-transport measurements in fibroblasts using a newly developed sensitive assay based on tandem mass spectrometry. This variant, which we identified in 57 of 236 individuals of our cohort, introduces a functional upstream out-of-frame translation initiation codon. We show that the codon suppresses translation from the wild-type ATG of SLC22A5, resulting in reduced OCTN2 protein levels and concomitantly lower transport activity. With an allele frequency of 24.2% the c.-149G>A variant is the most frequent cause of primary carnitine deficiency in our cohort and may explain other reported cases with an incomplete genetic diagnosis. Individuals carrying this variant should be clinically re-evaluated and monitored to determine if this variant has clinical consequences.

8.
Am J Physiol Endocrinol Metab ; 317(3): E494-E502, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31237451

RESUMO

Bile acids, glucagon-like peptide-1 (GLP-1), and fibroblast growth factor 19 (FGF19) play an important role in postprandial metabolism. In this study, we investigated the postprandial bile acid response in plasma and its relation to insulin, GLP-1, and FGF19. First, we investigated the postprandial response to 40-h fast. Then we administered glycine-conjugated deoxycholic acid (gDCA) with the meal. We performed two separate observational randomized crossover studies on healthy, lean men. In experiment 1: we tested 4-h mixed meal after an overnight fast and a 40-h fast. In experiment 2, we tested a 4-h mixed meal test with and without gDCA supplementation. Both studies measured postprandial glucose, insulin, bile acids, GLP-1, and FGF19. In experiment 1, 40 h of fasting induced insulin resistance and increased postprandial GLP-1 and FGF19 concentrations. After an overnight fast, we observed strong correlations between postprandial insulin and gDCA levels at specific time points. In experiment 2, administration of gDCA increased GLP-1 levels and lowered late postprandial glucose without effect on FGF19. Energy expenditure was not affected by gDCA administration. Unexpectedly, 40 h of fasting increased both GLP-1 and FGF19, where the former appeared bile acid independent and the latter bile acid dependent. Second, a single dose of gDCA increased postprandial GLP-1. Therefore, our data add complexity to the physiological regulation of the enterokines GLP-1 and FGF19 by bile acids.

9.
J Inherit Metab Dis ; 42(2): 197-208, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30723938

RESUMO

The laboratory diagnosis of inborn errors of metabolism has been revolutionized in recent years, thanks to the amazing developments in the field of DNA sequencing including whole exome and whole genome sequencing (WES and WGS). Interpretation of the results coming from WES and/or WGS analysis is definitely not trivial especially since the biological relevance of many of the variants identified by WES and/or WGS, have not been tested experimentally and prediction programs like POLYPHEN-2 and SIFT are far from perfect. Correct interpretation of WES and/or WGS results can only be achieved by performing functional studies at multiple levels (different metabolomics platforms, enzymology, in vitro and in vivo flux analysis), often requires studies in model organisms like zebra fish, Caenorhabditis elegans, Saccharomyces cerevisiae, mutant mice and others, and also requires the input of many different disciplines to make this Translational Metabolism approach effective.

10.
J Inherit Metab Dis ; 42(2): 303-312, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30793331

RESUMO

INTRODUCTION: Currently, no therapies are available for Zellweger spectrum disorders (ZSDs), a group of genetic metabolic disorders characterised by a deficiency of functional peroxisomes. In a previous study, we showed that oral cholic acid (CA) treatment can suppress bile acid synthesis in ZSD patients and, thereby, decrease plasma levels of toxic C27 -bile acid intermediates, one of the biochemical abnormalities in these patients. However, no effect on clinically relevant outcome measures could be observed after 9 months of CA treatment. It was noted that, in patients with advanced liver disease, caution is needed because of possible hepatotoxicity. METHODS: An extension study of the previously conducted pretest-posttest design study was conducted including 17 patients with a ZSD. All patients received oral CA for an additional period of 12 months, encompassing a total of 21 months of treatment. Multiple clinically relevant parameters and markers for bile acid synthesis were assessed after 15 and 21 months of treatment. RESULTS: Bile acid synthesis was still suppressed after 21 months of CA treatment, accompanied with reduced levels of C27 -bile acid intermediates in plasma. These levels significantly increased again after discontinuation of CA. No significant changes were found in liver tests, liver elasticity, coagulation parameters, fat-soluble vitamin levels or body weight. CONCLUSIONS: Although CA treatment did lead to reduced levels of toxic C27 -bile acid intermediates in ZSD patients without severe liver fibrosis or cirrhosis, no improvement of clinically relevant parameters was observed after 21 months of treatment. We discuss the implications for CA therapy in ZSD based on these results.

12.
FASEB J ; 33(3): 4355-4364, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30540494

RESUMO

Peroxisomes are essential organelles for the specialized oxidation of a wide variety of fatty acids, but they are also able to degrade fatty acids that are typically handled by mitochondria. Using a combination of pharmacological inhibition and clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR associated protein 9 genome editing technology to simultaneously manipulate peroxisomal and mitochondrial fatty acid ß-oxidation (FAO) in HEK-293 cells, we identified essential players in the metabolic crosstalk between these organelles. Depletion of carnitine palmitoyltransferase (CPT)2 activity through pharmacological inhibition or knockout (KO) uncovered a significant residual peroxisomal oxidation of lauric and palmitic acid, leading to the production of peroxisomal acylcarnitine intermediates. Generation and analysis of additional single- and double-KO cell lines revealed that the D-bifunctional protein (HSD17B4) and the peroxisomal ABC transporter ABCD3 are essential in peroxisomal oxidation of lauric and palmitic acid. Our results indicate that peroxisomes not only accept acyl-CoAs but can also oxidize acylcarnitines in a similar biochemical pathway. By using an Hsd17b4 KO mouse model, we demonstrated that peroxisomes contribute to the plasma acylcarnitine profile after acute inhibition of CPT2, proving in vivo relevance of this pathway. We summarize that peroxisomal FAO is important when mitochondrial FAO is defective or overloaded.-Violante, S., Achetib, N., van Roermund, C. W. T., Hagen, J., Dodatko, T., Vaz, F. M., Waterham, H. R., Chen, H., Baes, M., Yu, C., Argmann, C. A., Houten, S. M. Peroxisomes can oxidize medium- and long-chain fatty acids through a pathway involving ABCD3 and HSD17B4.

13.
Histochem Cell Biol ; 151(1): 85-90, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30159782

RESUMO

Uncoupling of mitochondrial proton pumping and adenosine triphosphate (ATP) production lowers mitochondrial efficiency. Current methods to determine mitochondrial efficiency require substantial amounts of tissue and permeabilization or isolation procedures. A simple histochemical method has been described by Meijer and Vloedman (Histochemistry 69:217-232, 1980, https://doi.org/10.1007/BF00489769 ), but this was not quantitative. We found linear correlations between (1) absorbance and sections thickness and (2) absorbance and incubation time. Because the method obeys Lambert-Beer's law, we can estimate ATP/O2 ratios for healthy and overloaded right-sided rat myocardium. We related mitochondrial efficiency to the ratio between cardiolipin and its precursor phosphatidylglycerol. We found a non-linear relationship between mitochondrial efficiency and this ratio, indicating that lower mitochondrial efficiency as found in experimental pulmonary hypertension may be due to altered composition of the mitochondrial inner membrane. We conclude that the histochemical method of Meijer and Vloedman can be applied to quantify mitochondrial efficiency.


Assuntos
Mitocôndrias/metabolismo , Miocárdio/metabolismo , Absorção Fisiológica , Animais , Biomarcadores/metabolismo , Cardiolipinas/metabolismo , Histocitoquímica , Hipertensão Pulmonar/metabolismo , Masculino , Prótons , Ratos , Ratos Wistar
14.
Biochim Biophys Acta Mol Basis Dis ; 1864(11): 3650-3658, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30251684

RESUMO

Barth syndrome (BTHS) is a rare X-linked disorder that is characterized by cardiac and skeletal myopathy, neutropenia and growth abnormalities. The disease is caused by mutations in the tafazzin (TAZ) gene encoding an enzyme involved in the acyl chain remodeling of the mitochondrial phospholipid cardiolipin (CL). Biochemically, this leads to decreased levels of mature CL and accumulation of the intermediate monolysocardiolipin (MLCL). At a cellular level, this causes mitochondrial fragmentation and reduced stability of the respiratory chain supercomplexes. However, the exact mechanism through which tafazzin deficiency leads to disease development remains unclear. We therefore aimed to elucidate the pathways affected in BTHS cells by employing proteomic and metabolic profiling assays. Complexome profiling of patient skin fibroblasts revealed significant effects for about 200 different mitochondrial proteins. Prominently, we found a specific destabilization of higher order oxidative phosphorylation (OXPHOS) supercomplexes, as well as changes in complexes involved in cristae organization and CL trafficking. Moreover, the key metabolic complexes 2-oxoglutarate dehydrogenase (OGDH) and branched-chain ketoacid dehydrogenase (BCKD) were profoundly destabilized in BTHS patient samples. Surprisingly, metabolic flux distribution assays using stable isotope tracer-based metabolomics did not show reduced flux through the TCA cycle. Overall, insights from analyzing the impact of TAZ mutations on the mitochondrial complexome provided a better understanding of the resulting functional and structural consequences and thus the pathological mechanisms leading to Barth syndrome.


Assuntos
Síndrome de Barth/patologia , Redes e Vias Metabólicas/genética , Membranas Mitocondriais/patologia , Transdução de Sinais/genética , Fatores de Transcrição/genética , Síndrome de Barth/genética , Cardiolipinas/metabolismo , Estudos de Casos e Controles , Fibroblastos , Voluntários Saudáveis , Humanos , Metabolômica , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Membranas Mitocondriais/metabolismo , Mutação , Fosforilação Oxidativa , Cultura Primária de Células , Proteômica , Pele/citologia , Pele/patologia , Fatores de Transcrição/metabolismo
15.
J Clin Endocrinol Metab ; 103(10): 3783-3791, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-30113646

RESUMO

Context: Type 2 diabetes and cardiovascular disease occur more frequently and at a younger age in South-Asians than Europeans. This may be related to differences in regulation of the fatty acid metabolism during aging. We compared age-related acylcarnitine and amino acid concentrations in Dutch and South-Asian Surinamese study participants. Methods: We measured types of acylcarnitine and amino acid concentrations in plasma (by tandem mass spectrometry) in a random subsample of 350 Dutch and 350 South-Asian Surinamese origin participants of the Healthy Life in an Urban Setting study (Amsterdam, Netherlands). We derived principal components (PCs) from the metabolites. Linear regression was used to assess differences in PCs and individual metabolite concentrations, and their age trends between the groups by sex. We adjusted for body mass index and intake of fat and total energy. Results: Mean age was 44.8 (SD, 13.3) years. Amino acid concentrations were higher among South-Asian Surinamese women compared with Dutch women; acylcarnitine and amino acid levels were higher among South-Asian Surinamese men than Dutch men. Metabolite levels increased similarly with age in both ethnic groups. Results remained similar after adjustment. Conclusion: Ethnic differences in metabolite concentrations suggest that fatty acid and amino acid metabolism are more dysregulated among South-Asian Surinamese compared with Dutch from a young age. During adulthood, metabolites increase similarly in both ethnic groups.


Assuntos
Aminoácidos/metabolismo , Grupo com Ancestrais do Continente Asiático/estatística & dados numéricos , Carnitina/análogos & derivados , Grupos Étnicos/estatística & dados numéricos , Grupo com Ancestrais do Continente Europeu/estatística & dados numéricos , Doenças Metabólicas/epidemiologia , Adolescente , Adulto , Fatores Etários , Idoso , Biomarcadores/análise , Carnitina/metabolismo , Estudos de Coortes , Estudos Transversais , Feminino , Seguimentos , Humanos , Masculino , Doenças Metabólicas/metabolismo , Pessoa de Meia-Idade , Países Baixos/epidemiologia , Prevalência , Prognóstico , Suriname/epidemiologia , Adulto Jovem
16.
Biochim Biophys Acta Biomembr ; 1860(11): 2404-2415, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29902419

RESUMO

BACKGROUND: Amphipathic cationic antimicrobial peptides (AMPs) TC19 and TC84, derived from the major AMPs of human blood platelets, thrombocidins, and Bactericidal Peptide 2 (BP2), a synthetic designer peptide showed to perturb the membrane of Bacillus subtilis. We aimed to determine the means by which the three AMPs cause membrane perturbation in vivo using B. subtilis and to evaluate whether the membrane alterations are dependent on the phospholipid composition of the membrane. METHODS: Physiological analysis was employed using Alexa Fluor 488 labelled TC84, various fluorescence dyes, fluorescent microscopy techniques and structured illumination microscopy. RESULTS: TC19, TC84 and BP2 created extensive fluidity domains in the membrane that are permeable, thus facilitating the entering of the peptides and the leakage of the cytosol. The direct interaction of the peptides with the bilayer create the fluid domains. The changes caused in the packing of the phospholipids lead to the delocalization of membrane bound proteins, thus contributing to the cell's destruction. The changes made to the membrane appeared to be not dependent on the composition of the phospholipid bilayer. CONCLUSIONS: The distortion caused to the fluidity of the membrane by the AMPs is sufficient to facilitate the entering of the peptides and leakage of the cytosol. GENERAL SIGNIFICANCE: Here we show in vivo that cationic AMPs cause "membrane leaks" at the site of membrane insertion by altering the organization and fluidity of the membrane. Our findings thus contribute to the understanding of the membrane perturbation characteristic of cationic AMPs.


Assuntos
Peptídeos Catiônicos Antimicrobianos/metabolismo , Bacillus subtilis/metabolismo , Parede Celular/metabolismo , Fluidez de Membrana/fisiologia , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/genética , Parede Celular/química , Humanos , Maleimidas/química , Fluidez de Membrana/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Microscopia de Fluorescência , Fosfolipídeos/química
17.
Sci Rep ; 8(1): 9562, 2018 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-29934543

RESUMO

Activation of brown adipose tissue (BAT) contributes to total body energy expenditure through energy dissipation as heat. Activated BAT increases the clearance of lipids and glucose from the circulation, but how BAT accommodates large influx of multiple substrates is not well defined. The purpose of this work was to assess the metabolic fluxes in brown adipocytes during ß3-adrenergic receptor (ß3-AR) activation.T37i murine preadipocytes were differentiated into brown adipocytes and we used Seahorse respirometry employing a set of specific substrate inhibitors in the presence or absence of ß3-AR agonist CL316,243. The main substrate used by these brown adipocytes were fatty acids, which were oxidized equally during activation as well as during resting condition. [U-13C]-glucose tracer-based metabolomics revealed that the flux through the TCA cycle was enhanced and regulated by pyruvate dehydrogenase (PDH) activity. Based on 13C-tracer incorporation in lipids, it appeared that most glucose was oxidized via TCA cycle activity, while some was utilized for glycerol-3-phosphate synthesis to replenish the triglyceride pool. Collectively, we show that while fatty acids are the main substrates for oxidation, glucose is also oxidized to meet the increased energy demand during short term ß3-AR activation. PDH plays an important role in directing glucose carbons towards oxidation.


Assuntos
Adipócitos Marrons/metabolismo , Metabolismo Energético , Complexo Piruvato Desidrogenase/metabolismo , Receptores Adrenérgicos beta 3/metabolismo , Adipócitos Marrons/citologia , Diferenciação Celular , Linhagem Celular , Glucose/metabolismo , Glicólise , Espaço Intracelular/metabolismo , Lipogênese , Oxirredução , Triglicerídeos/metabolismo
18.
Mol Genet Metab ; 124(1): 50-56, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29580649

RESUMO

INTRODUCTION: Galactokinase (GALK) deficiency causes cataract leading to severe developmental consequences unless treated early. Because of the easy prevention and rapid reversibility of cataract with treatment, the Dutch Health Council advised to include GALK deficiency in the Dutch newborn screening program. The aim of this study is to establish the optimal screening method and cut-off value (COV) for GALK deficiency screening by performing a systematic review of the literature of screening strategies and total galactose (TGAL) values and by evaluating TGAL values in the first week of life in a cohort of screened newborns in the Netherlands. METHODS: Systematic literature search strategies in OVID MEDLINE and OVID EMBASE were developed and study selection, data collection and analyses were performed by two independent investigators. A range of TGAL values measured by the Quantase Neonatal Total Galactose screening assay in a cohort of Dutch newborns in 2007 was evaluated. RESULTS: Eight publications were included in the systematic review. All four studies describing screening strategies used TGAL as the primary screening marker combined with galactose-1-phosphate uridyltransferase (GALT) measurement that is used for classical galactosemia screening. TGAL COVs of 2200 µmol/L, 1665 µmol/L and 1110 µmol/L blood resulted in positive predictive values (PPV) of 100%, 82% and 10% respectively. TGAL values measured in the newborn period were reported for 39 GALK deficiency patients with individual values ranging from 3963 to 8159 µmol/L blood and 2 group values with mean 8892 µmol/L blood (SD ±â€¯5243) and 4856 µmol/L blood (SD ±â€¯461). Dutch newborn screening data of 72,786 newborns from 2007 provided a median TGAL value of 110 µmol/L blood with a range of 30-2431 µmol/L blood. CONCLUSION: Based on TGAL values measured in GALK deficiency patients reported in the literature and TGAL measurements in the Dutch cohort by newborn screening we suggest to perform the GALK screening with TGAL as a primary marker with a COV of 2500 µmol/L blood, combined with GALT enzyme activity measurement as used in the classical galactosemia screening, to ensure detection of GALK deficiency patients and minimize false positive referrals.


Assuntos
Galactosemias/diagnóstico , Triagem Neonatal/métodos , Guias de Prática Clínica como Assunto , Catarata/prevenção & controle , Galactose/sangue , Galactosemias/epidemiologia , Humanos , Recém-Nascido , Países Baixos/epidemiologia , Ensaios Clínicos Controlados Aleatórios como Assunto , Estudos Retrospectivos
19.
J Med Genet ; 55(5): 351-358, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29437868

RESUMO

BACKGROUND: Two recombinant enzymes (agalsidase alfa 0.2 mg/kg/every other week and agalsidase beta 1.0 mg/kg/every other week) have been registered for the treatment of Fabry disease (FD), at equal high costs. An independent international initiative compared clinical and biochemical outcomes of the two enzymes. METHODS: In this multicentre retrospective cohort study, clinical event rate, left ventricular mass index (LVMI), estimated glomerular filtration rate (eGFR), antibody formation and globotriaosylsphingosine (lysoGb3) levels were compared between patients with FD treated with agalsidase alfa and beta at their registered dose after correction for phenotype and sex. RESULTS: 387 patients (192 women) were included, 248 patients received agalsidase alfa. Mean age at start of enzyme replacement therapy was 46 (±15) years. Propensity score matched analysis revealed a similar event rate for both enzymes (HR 0.96, P=0.87). The decrease in plasma lysoGb3 was more robust following treatment with agalsidase beta, specifically in men with classical FD (ß: -18 nmol/L, P<0.001), persisting in the presence of antibodies. The risk to develop antibodies was higher for patients treated with agalsidase beta (OR 2.8, P=0.04). LVMI decreased in a higher proportion following the first year of agalsidase beta treatment (OR 2.27, P=0.03), while eGFR slopes were similar. CONCLUSIONS: Treatment with agalsidase beta at higher dose compared with agalsidase alfa does not result in a difference in clinical events, which occurred especially in those with more advanced disease. A greater biochemical response, also in the presence of antibodies, and better reduction in left ventricular mass was observed with agalsidase beta.


Assuntos
Doença de Fabry/tratamento farmacológico , Isoenzimas/administração & dosagem , Proteínas Recombinantes/administração & dosagem , alfa-Galactosidase/administração & dosagem , Adulto , Estudos de Coortes , Terapia de Reposição de Enzimas , Doença de Fabry/genética , Doença de Fabry/patologia , Feminino , Taxa de Filtração Glomerular/efeitos dos fármacos , Humanos , Isoenzimas/genética , Masculino , Pessoa de Meia-Idade , Proteínas Recombinantes/genética , Estudos Retrospectivos , Resultado do Tratamento , alfa-Galactosidase/genética
20.
J Med Genet ; 55(1): 39-47, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28916646

RESUMO

OBJECTIVE: To demonstrate that mutations in the phosphatidylglycerol remodelling enzyme SERAC1 can cause juvenile-onset complicated hereditary spastic paraplegia (cHSP) clusters, thus adding SERAC1 to the increasing number of complex lipid cHSP genes. METHODS: Combined genomic and functional validation studies (whole-exome sequencing, mRNA, cDNA and protein), biomarker investigations (3-methyl-glutaconic acid, filipin staining and phosphatidylglycerols PG34:1/PG36:1), and clinical and imaging phenotyping were performed in six affected subjects from two different branches of a large consanguineous family. RESULTS: 5 of 6 affected subjects shared cHSP as a common disease phenotype. Three subjects presented with juvenile-onset oligosystemic cHSP, still able to walk several miles at age >10-20 years. This benign phenotypic cluster and disease progression is strikingly divergent to the severe infantile phenotype of all SERAC1 cases reported so far. Two family members showed a more multisystemic juvenile-onset cHSP, indicating an intermediate phenotype between the benign oligosystemic cHSP and the classic infantile SERAC1 cluster. The homozygous splice mutation led to loss of the full-length SERAC1 protein and impaired phosphatidylglycerol PG34:1/PG36:1 remodelling. These phosphatidylglycerol changes, however, were milder than in classic infantile-onset SERAC1 cases, which might partially explain the milder SERAC1 phenotype. CONCLUSIONS: Our findings add SERAC1 to the increasing list of complex lipid cHSP genes. At the same time they redefine the phenotypic spectrum of SERAC1 deficiency. It is associated not only with the severe infantile-onset 'Methylglutaconic aciduria, Deafness, Encephalopathy, Leigh-like' syndrome (MEGDEL syndrome), but also with oligosystemic juvenile-onset cHSP as part of the now unfolding SERAC1 deficiency spectrum.


Assuntos
Hidrolases de Éster Carboxílico/deficiência , Mutação/genética , Sítios de Splice de RNA/genética , Paraplegia Espástica Hereditária/genética , Sequência de Bases , Biomarcadores/metabolismo , Líquidos Corporais/metabolismo , Hidrolases de Éster Carboxílico/genética , Hidrolases de Éster Carboxílico/metabolismo , Família , Feminino , Fibroblastos/metabolismo , Genômica , Homozigoto , Humanos , Íntrons/genética , Imagem por Ressonância Magnética , Masculino , Linhagem , Fenótipo , Fosfatidilgliceróis/metabolismo
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