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1.
J Inherit Metab Dis ; 45(4): 748-758, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35527402

RESUMO

Messenger RNA (mRNA) has emerged as a novel therapeutic approach for inborn errors of metabolism. Classic galactosemia (CG) is an inborn error of galactose metabolism caused by a severe deficiency of galactose-1-phosphate:uridylyltransferase (GALT) activity leading to neonatal illness and chronic impairments affecting the brain and female gonads. In this proof of concept study, we used our zebrafish model for CG to evaluate the potential of human GALT mRNA (hGALT mRNA) packaged in two different lipid nanoparticles to restore GALT expression and activity at early stages of development. Both one cell-stage and intravenous single-dose injections resulted in hGALT protein expression and enzyme activity in the CG zebrafish (galt knockout) at 5 days post fertilization (dpf). Moreover, the levels of galactose-1-phosphate (Gal-1-P) and galactonate, metabolites that accumulate because of the deficiency, showed a decreasing trend. LNP-packaged mRNA was effectively translated and processed in the CG zebrafish without signs of toxicity. This study shows that mRNA therapy restores GALT protein and enzyme activity in the CG zebrafish model, and that the zebrafish is a suitable system to test this approach. Further studies are warranted to assess whether repeated injections safely mitigate the chronic impairments of this disease.


Assuntos
Galactosemias , Animais , Feminino , Galactose/metabolismo , Galactosemias/diagnóstico , Galactosemias/genética , Galactosemias/terapia , Humanos , Recém-Nascido , Lipossomos , Nanopartículas , Nucleotidiltransferases , RNA Mensageiro/genética , UTP-Hexose-1-Fosfato Uridililtransferase/metabolismo , Peixe-Zebra/genética , Peixe-Zebra/metabolismo
2.
J Inherit Metab Dis ; 44(5): 1113-1123, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-33843072

RESUMO

The current diagnostic work-up of inborn errors of metabolism (IEM) is rapidly moving toward integrative analytical approaches. We aimed to develop an innovative, targeted urine metabolomics (TUM) screening procedure to accelerate the diagnosis of patients with IEM. Urinary samples, spiked with three stable isotope-labeled internal standards, were analyzed for 258 diagnostic metabolites with an ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) configuration run in positive and negative ESI modes. The software automatically annotated peaks, corrected for peak overloading, and reported peak quality and shifting. Robustness and reproducibility were satisfactory for most metabolites. Z-scores were calculated against four age-group-matched control cohorts. Disease phenotypes were scored based on database metabolite matching. Graphical reports comprised a needle plot, annotating abnormal metabolites, and a heatmap showing the prioritized disease phenotypes. In the clinical validation, we analyzed samples of 289 patients covering 78 OMIM phenotypes from 12 of the 15 society for the study of inborn errors of metabolism (SSIEM) disease groups. The disease groups include disorders in the metabolism of amino acids, fatty acids, ketones, purines and pyrimidines, carbohydrates, porphyrias, neurotransmitters, vitamins, cofactors, and creatine. The reporting tool easily and correctly diagnosed most samples. Even subtle aberrant metabolite patterns as seen in mild multiple acyl-CoA dehydrogenase deficiency (GAII) and maple syrup urine disease (MSUD) were correctly called without difficulty. Others, like creatine transporter deficiency, are illustrative of IEM that remain difficult to diagnose. We present TUM as a powerful diagnostic screening tool that merges most urinary diagnostic assays expediting the diagnostics for patients suspected of an IEM.


Assuntos
Erros Inatos do Metabolismo/diagnóstico , Erros Inatos do Metabolismo/urina , Metaboloma , Urinálise/métodos , Biomarcadores/urina , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Metabolômica/métodos , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem/métodos
3.
J Inherit Metab Dis ; 43(3): 392-408, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31808946

RESUMO

Since the first description of galactosemia in 1908 and despite decades of research, the pathophysiology is complex and not yet fully elucidated. Galactosemia is an inborn error of carbohydrate metabolism caused by deficient activity of any of the galactose metabolising enzymes. The current standard of care, a galactose-restricted diet, fails to prevent long-term complications. Studies in cellular and animal models in the past decades have led to an enormous progress and advancement of knowledge. Summarising current evidence in the pathophysiology underlying hereditary galactosemia may contribute to the identification of treatment targets for alternative therapies that may successfully prevent long-term complications. A systematic review of cellular and animal studies reporting on disease complications (clinical signs and/or biochemical findings) and/or treatment targets in hereditary galactosemia was performed. PubMed/MEDLINE, EMBASE, and Web of Science were searched, 46 original articles were included. Results revealed that Gal-1-P is not the sole pathophysiological agent responsible for the phenotype observed in galactosemia. Other currently described contributing factors include accumulation of galactose metabolites, uridine diphosphate (UDP)-hexose alterations and subsequent impaired glycosylation, endoplasmic reticulum (ER) stress, altered signalling pathways, and oxidative stress. galactokinase (GALK) inhibitors, UDP-glucose pyrophosphorylase (UGP) up-regulation, uridine supplementation, ER stress reducers, antioxidants and pharmacological chaperones have been studied, showing rescue of biochemical and/or clinical symptoms in galactosemia. Promising co-adjuvant therapies include antioxidant therapy and UGP up-regulation. This systematic review provides an overview of the scattered information resulting from animal and cellular studies performed in the past decades, summarising the complex pathophysiological mechanisms underlying hereditary galactosemia and providing insights on potential treatment targets.


Assuntos
Galactosemias/genética , Galactosemias/fisiopatologia , Animais , Modelos Animais de Doenças , Galactoquinase/genética , Galactoquinase/metabolismo , Galactose/metabolismo , Galactosemias/metabolismo , Galactosemias/terapia , Genótipo , Humanos , Estresse Oxidativo , Fenótipo , UDPglucose 4-Epimerase/genética , UDPglucose 4-Epimerase/metabolismo , UTP-Hexose-1-Fosfato Uridililtransferase/genética , UTP-Hexose-1-Fosfato Uridililtransferase/metabolismo
4.
J Mol Cell Cardiol ; 76: 208-17, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25173922

RESUMO

In the insulin resistant heart, energy fuel selection shifts away from glucose utilization towards almost complete dependence on long-chain fatty acids (LCFA). This shift results in excessive cardiac lipid accumulation and eventually heart failure. Lipid-induced cardiomyopathy may be averted by strategies that increase glucose uptake without elevating LCFA uptake. Protein kinase-D1 (PKD1) is involved in contraction-induced glucose, but not LCFA, uptake allowing to hypothesize that this kinase is an attractive target to treat lipid-induced cardiomyopathy. For this, cardiospecific constitutively active PKD1 overexpression (caPKD1)-mice were subjected to an insulin resistance-inducing high fat-diet for 20-weeks. Substrate utilization was assessed by microPET and cardiac function by echocardiography. Cardiomyocytes were isolated for measurement of substrate uptake, lipid accumulation and insulin sensitivity. Wild-type mice on a high fat-diet displayed increased basal myocellular LCFA uptake, increased lipid deposition, greatly impaired insulin signaling, and loss of insulin-stimulated glucose and LCFA uptake, which was associated with concentric hypertrophic remodeling. The caPKD1 mice on high-fat diet showed none of these characteristics, whereas on low-fat diet a shift towards cardiac glucose utilization in combination with hypertrophy and ventricular dilation was observed. In conclusion, these data suggest that PKD pathway activation may be an attractive therapeutic strategy to mitigate lipid accumulation, insulin resistance and maladaptive remodeling in the lipid-overloaded heart, but this requires further investigation.


Assuntos
Cardiomiopatia Dilatada/enzimologia , Resistência à Insulina , Proteína Quinase C/metabolismo , Animais , Dieta Hiperlipídica/efeitos adversos , Feminino , Expressão Gênica , Ventrículos do Coração/metabolismo , Ventrículos do Coração/patologia , Histona Desacetilases/metabolismo , Metabolismo dos Lipídeos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Miocárdio/enzimologia , Miocárdio/patologia , Miócitos Cardíacos/enzimologia , Fosforilação , Proteína Quinase C/genética , Processamento de Proteína Pós-Traducional
5.
Mol Genet Metab Rep ; 38: 101057, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38469096

RESUMO

The authors report the natural history of three patients with late-diagnosed Classic Galactosemia (CG) (at 16, 19 and 28 years). This was due to a combination of factors: absence of neonatal screening, absence of some typical acute neonatal symptoms, and negative galactosemia screening. This report underlines the value of neonatal screening and the importance of further diagnostic testing in case of late-onset manifestations.

6.
J Mol Cell Cardiol ; 55: 165-73, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23159540

RESUMO

During lipid oversupply, the heart becomes insulin resistant, as exemplified by defective insulin-stimulated glucose uptake, and will develop diastolic dysfunction. In the healthy heart, not only insulin, but also increased contractile activity stimulates glucose uptake. Upon increased contraction both AMP-activated protein kinase (AMPK) and protein kinase D (PKD) are activated, and mediate the stimulation of glucose uptake into cardiomyocytes. Therefore, each of these kinases is a potential therapeutic target in the diabetic heart because they may serve to bypass defective insulin-stimulated glucose uptake. To test the preventive potential of these kinases against loss of insulin-stimulated glucose uptake, AMPK or PKD were adenovirally overexpressed in primary cultures of insulin resistant cardiomyocytes for assaying substrate uptake, insulin responsiveness and lipid accumulation. To induce insulin resistance and lipid loading, rat primary cardiomyocytes were cultured in the presence of high insulin (100 nM; HI) or high palmitate (palmitate/BSA: 3/1; HP). HI and HP each reduced insulin responsiveness, and increased basal palmitate uptake and lipid storage. Overexpression of each of the kinases prevented loss of insulin-stimulated glucose uptake. Overexpression of AMPK also prevented loss of insulin signaling in HI- and HP-cultured cardiomyocytes, but did not prevent lipid accumulation. In contrast, overexpression of PKD prevented lipid accumulation, but not loss of insulin signaling in HI- and HP-cultured cardiomyocytes. In conclusion, AMPK and PKD prevent loss of insulin-stimulated glucose uptake into cardiomyocytes cultured under insulin resistance-inducing conditions through different mechanisms. This article is part of a Special Issue entitled "Focus on Cardiac Metabolism".


Assuntos
Proteínas Quinases Ativadas por AMP/genética , Resistência à Insulina/genética , Metabolismo dos Lipídeos , Miócitos Cardíacos/metabolismo , Proteína Quinase C/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Expressão Gênica , Glucose/metabolismo , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Insulina/metabolismo , Masculino , Palmitatos/metabolismo , Proteína Quinase C/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Transdução de Sinais
7.
J Biol Chem ; 287(44): 37530-9, 2012 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-22936810

RESUMO

Cardiac glucose utilization is regulated by reversible translocation of the glucose transporter GLUT4 from intracellular stores to the plasma membrane. During the onset of diet-induced insulin resistance, elevated lipid levels in the circulation interfere with insulin-stimulated GLUT4 translocation, leading to impaired glucose utilization. Recently, we identified vesicle-associated membrane protein (VAMP) 2 and 3 to be required for insulin- and contraction-stimulated GLUT4 translocation, respectively, in cardiomyocytes. Here, we investigated whether overexpression of VAMP2 and/or VAMP3 could protect insulin-stimulated GLUT4 translocation under conditions of insulin resistance. HL-1 atrial cardiomyocytes transiently overexpressing either VAMP2 or VAMP3 were cultured for 16 h with elevated concentrations of palmitate and insulin. Upon subsequent acute stimulation with insulin, we measured GLUT4 translocation, plasmalemmal presence of the fatty acid transporter CD36, and myocellular lipid accumulation. Overexpression of VAMP3, but not VAMP2, completely prevented lipid-induced inhibition of insulin-stimulated GLUT4 translocation. Furthermore, the plasmalemmal presence of CD36 and intracellular lipid levels remained normal in cells overexpressing VAMP3. However, insulin signaling was not retained, indicating an effect of VAMP3 overexpression downstream of PKB/Akt. Furthermore, we revealed that endogenous VAMP3 is bound by the contraction-activated protein kinase D (PKD), and contraction and VAMP3 overexpression protect insulin-stimulated GLUT4 translocation via a common mechanism. These observations indicate that PKD activates GLUT4 translocation via a VAMP3-dependent trafficking step, which pathway might be valuable to rescue constrained glucose utilization in the insulin-resistant heart.


Assuntos
Transportador de Glucose Tipo 4/metabolismo , Resistência à Insulina , Miócitos Cardíacos/metabolismo , Proteína 2 Associada à Membrana da Vesícula/metabolismo , Proteína 3 Associada à Membrana da Vesícula/metabolismo , Animais , Antígenos CD36/metabolismo , Linhagem Celular , Gorduras na Dieta/farmacologia , Expressão Gênica , Cardiopatias/metabolismo , Cardiopatias/patologia , Insulina/farmacologia , Insulina/fisiologia , Metabolismo dos Lipídeos , Masculino , Camundongos , Contração Miocárdica , Miócitos Cardíacos/patologia , Miócitos Cardíacos/fisiologia , Palmitatos/farmacologia , Proteína Quinase C/metabolismo , Transporte Proteico , Ratos , Ratos Endogâmicos Lew , Transdução de Sinais , Proteína 2 Associada à Membrana da Vesícula/genética , Proteína 3 Associada à Membrana da Vesícula/genética
8.
Biochem J ; 448(1): 43-53, 2012 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-22780108

RESUMO

An increased cardiac fatty acid supply and increased sarcolemmal presence of the long-chain fatty acid transporter CD36 are associated with and contribute to impaired cardiac insulin sensitivity and function. In the present study we aimed at preventing the development of insulin resistance and contractile dysfunction in cardiomyocytes by blocking CD36-mediated palmitate uptake. Insulin resistance and contractile dysfunction were induced in primary cardiomyocytes by 48 h incubation in media containing either 100 nM insulin (high insulin; HI) or 200 µM palmitate (high palmitate; HP). Under both culture conditions, insulin-stimulated glucose uptake and Akt phosphorylation were abrogated or markedly reduced. Furthermore, cardiomyocytes cultured in each medium displayed elevated sarcolemmal CD36 content, increased basal palmitate uptake, lipid accumulation and decreased sarcomere shortening. Immunochemical CD36 inhibition enhanced basal glucose uptake and prevented elevated basal palmitate uptake, triacylglycerol accumulation and contractile dysfunction in cardiomyocytes cultured in either medium. Additionally, CD36 inhibition prevented loss of insulin signalling in cells cultured in HP, but not in HI medium. In conclusion, CD36 inhibition prevents lipid accumulation and lipid-induced contractile dysfunction in cardiomyocytes, but probably independently of effects on insulin signalling. Nonetheless, pharmacological CD36 inhibition may be considered as a treatment strategy to counteract impaired functioning of the lipid-loaded heart.


Assuntos
Antígenos CD36/fisiologia , Resistência à Insulina/fisiologia , Miócitos Cardíacos/metabolismo , Palmitatos/metabolismo , Animais , Transporte Biológico , Sinalização do Cálcio/efeitos dos fármacos , Células Cultivadas/efeitos dos fármacos , Células Cultivadas/metabolismo , Cardiomiopatias Diabéticas/etiologia , Cardiomiopatias Diabéticas/metabolismo , Cardiomiopatias Diabéticas/prevenção & controle , Ácidos Graxos/metabolismo , Glucose/metabolismo , Insulina/farmacologia , Masculino , Mitocôndrias Cardíacas/metabolismo , Contração Miocárdica , Miócitos Cardíacos/efeitos dos fármacos , Palmitatos/farmacologia , Fosforilação/efeitos dos fármacos , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Endogâmicos Lew , Sarcolema/metabolismo , Sarcômeros/ultraestrutura , Transdução de Sinais/efeitos dos fármacos , Triglicerídeos/metabolismo
9.
Orphanet J Rare Dis ; 18(1): 95, 2023 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-37101200

RESUMO

BACKGROUND: Inherited Metabolic Disorders (IMDs) are rare diseases where one impaired protein leads to a cascade of changes in the adjacent chemical conversions. IMDs often present with non-specific symptoms, a lack of a clear genotype-phenotype correlation, and de novo mutations, complicating diagnosis. Furthermore, products of one metabolic conversion can be the substrate of another pathway obscuring biomarker identification and causing overlapping biomarkers for different disorders. Visualization of the connections between metabolic biomarkers and the enzymes involved might aid in the diagnostic process. The goal of this study was to provide a proof-of-concept framework for integrating knowledge of metabolic interactions with real-life patient data before scaling up this approach. This framework was tested on two groups of well-studied and related metabolic pathways (the urea cycle and pyrimidine de-novo synthesis). The lessons learned from our approach will help to scale up the framework and support the diagnosis of other less-understood IMDs. METHODS: Our framework integrates literature and expert knowledge into machine-readable pathway models, including relevant urine biomarkers and their interactions. The clinical data of 16 previously diagnosed patients with various pyrimidine and urea cycle disorders were visualized on the top 3 relevant pathways. Two expert laboratory scientists evaluated the resulting visualizations to derive a diagnosis. RESULTS: The proof-of-concept platform resulted in varying numbers of relevant biomarkers (five to 48), pathways, and pathway interactions for each patient. The two experts reached the same conclusions for all samples with our proposed framework as with the current metabolic diagnostic pipeline. For nine patient samples, the diagnosis was made without knowledge about clinical symptoms or sex. For the remaining seven cases, four interpretations pointed in the direction of a subset of disorders, while three cases were found to be undiagnosable with the available data. Diagnosing these patients would require additional testing besides biochemical analysis. CONCLUSION: The presented framework shows how metabolic interaction knowledge can be integrated with clinical data in one visualization, which can be relevant for future analysis of difficult patient cases and untargeted metabolomics data. Several challenges were identified during the development of this framework, which should be resolved before this approach can be scaled up and implemented to support the diagnosis of other (less understood) IMDs. The framework could be extended with other OMICS data (e.g. genomics, transcriptomics), and phenotypic data, as well as linked to other knowledge captured as Linked Open Data.


Assuntos
Doenças Metabólicas , Humanos , Doenças Metabólicas/diagnóstico , Biomarcadores , Genômica , Metabolômica/métodos , Pirimidinas
10.
Cell Mol Life Sci ; 68(15): 2525-38, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21547502

RESUMO

Cardiomyocytes use glucose as well as fatty acids for ATP production. These substrates are transported into the cell by glucose transporter 4 (GLUT4) and the fatty acid transporter CD36. Besides being located at the sarcolemma, GLUT4 and CD36 are stored in intracellular compartments. Raised plasma insulin concentrations and increased cardiac work will stimulate GLUT4 as well as CD36 to translocate to the sarcolemma. As so far studied, signaling pathways that regulate GLUT4 translocation similarly affect CD36 translocation. During the development of insulin resistance and type 2 diabetes, CD36 becomes permanently localized at the sarcolemma, whereas GLUT4 internalizes. This juxtaposed positioning of GLUT4 and CD36 is important for aberrant substrate uptake in the diabetic heart: chronically increased fatty acid uptake at the expense of glucose. To explain the differences in subcellular localization of GLUT4 and CD36 in type 2 diabetes, recent research has focused on the role of proteins involved in trafficking of cargo between subcellular compartments. Several of these proteins appear to be similarly involved in both GLUT4 and CD36 translocation. Others, however, have different roles in either GLUT4 or CD36 translocation. These trafficking components, which are differently involved in GLUT4 or CD36 translocation, may be considered novel targets for the development of therapies to restore the imbalanced substrate utilization that occurs in obesity, insulin resistance and diabetic cardiomyopathy.


Assuntos
Antígenos CD36/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Miócitos Cardíacos/metabolismo , Animais , Ácidos Graxos/metabolismo , Glucose/metabolismo , Humanos , Espaço Intracelular/metabolismo , Modelos Biológicos , Transporte Proteico
11.
Am J Physiol Endocrinol Metab ; 301(4): E618-27, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21712535

RESUMO

Cardiac patients often are obese and have hypertension, but in most studies these conditions are investigated separately. Here, we aimed at 1) elucidating the interaction of metabolic and mechanophysical stress in the development of cardiac dysfunction in mice and 2) preventing this interaction by ablation of the fatty acid transporter CD36. Male wild-type (WT) C57Bl/6 mice and CD36(-/-) mice received chow or Western-type diet (WTD) for 10 wk and then underwent a sham surgery or transverse aortic constriction (TAC) under anesthesia. After a 6-wk continuation of the diet, cardiac function, morphology, lipid profiles, and molecular parameters were assessed. WTD administration affected body and organ weights of WT and CD36(-/-) mice, but it affected only plasma glucose and insulin concentrations in WT mice. Cardiac lipid concentrations increased in WT mice receiving WTD, decreased in CD36(-/-) on chow, and remained unchanged in CD36(-/-) receiving WTD. TAC induced cardiac hypertrophy in WT mice on chow but did not affect cardiac function and cardiac lipid concentrations. WTD or CD36 ablation worsened the outcome of TAC. Ablation of CD36 protected against the WTD-related aggravation of cardiac functional and structural changes induced by TAC. In conclusion, cardiac dysfunction and remodeling worsen when the heart is exposed to two stresses, metabolic and mechanophysical, at the same time. CD36 ablation prevents the metabolic stress resulting from a WTD. Thus, metabolic conditions are a critical factor for the compromised heart and provide new targets for metabolic manipulation in cardioprotection.


Assuntos
Antígenos CD36/genética , Cardiomegalia/metabolismo , Miocárdio/metabolismo , Animais , Estenose da Valva Aórtica/complicações , Glicemia/metabolismo , Antígenos CD36/metabolismo , Cardiomegalia/etiologia , Cardiomegalia/fisiopatologia , Dieta , Coração/fisiopatologia , Masculino , Camundongos , Camundongos Knockout , Miocárdio/patologia , Obesidade/complicações
12.
Am J Physiol Cell Physiol ; 298(6): C1549-59, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20375272

RESUMO

Insulin and contraction stimulate both cardiac glucose and long-chain fatty acid (LCFA) uptake via translocation of the substrate transporters GLUT4 and CD36, respectively, from intracellular compartments to the sarcolemma. Little is known about the role of vesicular trafficking elements in insulin- and contraction-stimulated glucose and LCFA uptake in the heart, especially whether certain trafficking elements are specifically involved in GLUT4 versus CD36 translocation. Therefore, we studied the role of coat proteins, actin- and microtubule-filaments and endosomal pH on glucose and LCFA uptake into primary cardiomyocytes under basal conditions and during stimulation with insulin or oligomycin (contraction-like AMP-activated protein kinase activator). Inhibition of coat protein targeting to Golgi/endosomes decreased insulin/oligomycin-stimulated glucose (-42%/-51%) and LCFA (-39%/-68%) uptake. Actin disruption decreased insulin/oligomycin-stimulated glucose uptake (-41%/-75%), while not affecting LCFA uptake. Microtubule disruption did not affect substrate uptake under any condition. Endosomal alkalinization increased basal sarcolemmal CD36 (2-fold), but not GLUT4, content, and concomitantly decreased basal intracellular membrane GLUT4 and CD36 content (-60% and -62%, respectively), indicating successful CD36 translocation and incomplete GLUT4 translocation. Additionally, endosomal alkalinization elevated basal LCFA uptake (1.4-fold) in a nonadditive manner to insulin/oligomycin, and decreased insulin/oligomycin-stimulated glucose uptake (-32%/-68%). In conclusion, 1) CD36 translocation, just like GLUT4 translocation, is a vesicle-mediated process depending on coat proteins, and 2) GLUT4 and CD36 trafficking are differentially dependent on endosomal pH and actin filaments. The latter conclusion suggests novel strategies to alter cardiac substrate preference as part of metabolic modulation therapy.


Assuntos
Citoesqueleto de Actina/metabolismo , Antígenos CD36/metabolismo , Desoxiglucose/metabolismo , Endossomos/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Miócitos Cardíacos/metabolismo , Ácido Palmítico/metabolismo , Proteínas Quinases Ativadas por AMP/metabolismo , Citoesqueleto de Actina/efeitos dos fármacos , Citoesqueleto de Actina/ultraestrutura , Animais , Transporte Biológico , Brefeldina A/farmacologia , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Proteína Coatomer/metabolismo , Colchicina/farmacologia , Endossomos/efeitos dos fármacos , Endossomos/ultraestrutura , Ativação Enzimática , Ativadores de Enzimas/farmacologia , Concentração de Íons de Hidrogênio , Insulina/metabolismo , Masculino , Contração Miocárdica , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/ultraestrutura , Oligomicinas/farmacologia , Transporte Proteico , Ratos , Ratos Endogâmicos Lew , Tiazolidinas/farmacologia , Moduladores de Tubulina/farmacologia
13.
Diabetes ; 66(6): 1521-1534, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28302654

RESUMO

Dietary fat overconsumption leads to myocardial lipid accumulation through mechanisms that are incompletely resolved. Previously, we identified increased translocation of the fatty acid transporter CD36 from its endosomal storage compartment to the sarcolemma as the primary mechanism of excessive myocellular lipid import. Here, we show that increased CD36 translocation is caused by alkalinization of endosomes resulting from inhibition of proton pumping activity of vacuolar-type H+-ATPase (v-ATPase). Endosomal alkalinization was observed in hearts from rats fed a lard-based high-fat diet and in rodent and human cardiomyocytes upon palmitate overexposure, and appeared as an early lipid-induced event preceding the onset of insulin resistance. Either genetic or pharmacological inhibition of v-ATPase in cardiomyocytes exposed to low palmitate concentrations reduced insulin sensitivity and cardiomyocyte contractility, which was rescued by CD36 silencing. The mechanism of palmitate-induced v-ATPase inhibition involved its dissociation into two parts: the cytosolic V1 and the integral membrane V0 subcomplex. Interestingly, oleate also inhibits v-ATPase function, yielding triacylglycerol accumulation but not insulin resistance. In conclusion, lipid oversupply increases CD36-mediated lipid uptake that directly impairs v-ATPase function. This feeds forward to enhanced CD36 translocation and further increased lipid uptake. In the case of palmitate, its accelerated uptake ultimately precipitates into cardiac insulin resistance and contractile dysfunction.


Assuntos
Antígenos CD36/metabolismo , Endossomos/efeitos dos fármacos , Glucose/metabolismo , Coração/efeitos dos fármacos , Resistência à Insulina , Contração Miocárdica/efeitos dos fármacos , Miocárdio/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Palmitatos/farmacologia , ATPases Vacuolares Próton-Translocadoras/antagonistas & inibidores , Animais , Western Blotting , Radioisótopos de Carbono , Células Cultivadas , Desoxiglucose/metabolismo , Dieta Hiperlipídica , Endossomos/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Células-Tronco Pluripotentes Induzidas , Masculino , Miócitos Cardíacos/metabolismo , Cadeias Pesadas de Miosina/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Endogâmicos Lew , Triglicerídeos/metabolismo , Trítio , Troponina T/genética
14.
Diabetes ; 65(10): 2920-31, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27422385

RESUMO

Glucokinase (Gck) is a critical regulator of glucose-induced insulin secretion by pancreatic ß-cells. It has been suggested to also play an important role in glucose signaling in neurons of the ventromedial hypothalamic nucleus (VMN), a brain nucleus involved in the control of glucose homeostasis and feeding. To test the role of Gck in VMN glucose sensing and physiological regulation, we studied mice with genetic inactivation of the Gck gene in Sf1 neurons of the VMN (Sf1Gck(-/-) mice). Compared with control littermates, Sf1Gck(-/-) mice displayed increased white fat mass and adipocyte size, reduced lean mass, impaired hypoglycemia-induced glucagon secretion, and a lack of parasympathetic and sympathetic nerve activation by neuroglucopenia. However, these phenotypes were observed only in female mice. To determine whether Gck was required for glucose sensing by Sf1 neurons, we performed whole-cell patch clamp analysis of brain slices from control and Sf1Gck(-/-) mice. Absence of Gck expression did not prevent the glucose responsiveness of glucose-excited or glucose-inhibited Sf1 neurons in either sex. Thus Gck in the VMN plays a sex-specific role in the glucose-dependent control of autonomic nervous activity; this is, however, unrelated to the control of the firing activity of classical glucose-responsive neurons.


Assuntos
Glucoquinase/metabolismo , Hipotálamo/enzimologia , Adipócitos/citologia , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Feminino , Glucagon/metabolismo , Glucoquinase/genética , Glucose/farmacologia , Homeostase/efeitos dos fármacos , Hipotálamo/citologia , Hipotálamo/metabolismo , Masculino , Camundongos , Camundongos Mutantes , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Técnicas de Patch-Clamp , Núcleo Hipotalâmico Ventromedial/citologia , Núcleo Hipotalâmico Ventromedial/enzimologia , Núcleo Hipotalâmico Ventromedial/metabolismo
15.
Artigo em Inglês | MEDLINE | ID: mdl-22580174

RESUMO

The fatty acid transporter and scavenger receptor CD36 is increasingly being implicated in the pathogenesis of insulin resistance and its progression towards type 2 diabetes and associated cardiovascular complications. The redistribution of CD36 from intracellular stores to the plasma membrane is one of the earliest changes occurring in the heart during diet induced obesity and insulin resistance. This elicits an increased rate of fatty acid uptake and enhanced incorporation into triacylglycerol stores and lipid intermediates to subsequently interfere with insulin-induced GLUT4 recruitment (i.e., insulin resistance). In the present paper we discuss the potential of CD36 to serve as a target to rectify abnormal myocardial fatty acid uptake rates in cardiac lipotoxic diseases. Two approaches are described: (i) immunochemical inhibition of CD36 present at the sarcolemma and (ii) interference with the subcellular recycling of CD36. Using in vitro model systems of high-fat diet induced insulin resistance, the results indicate the feasibility of using CD36 as a target for adaptation of cardiac metabolic substrate utilization. In conclusion, CD36 deserves further attention as a promising therapeutic target to redirect fatty acid fluxes in the body.


Assuntos
Antígenos CD36/metabolismo , Cardiomiopatias Diabéticas/prevenção & controle , Resistência à Insulina , Lipotrópicos/uso terapêutico , Moduladores de Transporte de Membrana/uso terapêutico , Terapia de Alvo Molecular , Miocárdio/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Antígenos CD36/química , Cardiomiopatias Diabéticas/metabolismo , Coração/efeitos dos fármacos , Humanos , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipotrópicos/farmacologia , Moduladores de Transporte de Membrana/farmacologia
16.
Obesity (Silver Spring) ; 21(10): 2037-45, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23512311

RESUMO

OBJECTIVE: The scavenger receptor CD36 facilitates the cellular uptake of long-chain fatty acids. As CD36-deficiency attenuates the development of high fat diet (HFD)-induced obesity, the role of CD36-deficiency in preadipocyte recruitment and adipocyte function was set out to characterize. DESIGN AND METHODS: Fat cell size and number were determined in gonadal, visceral, and subcutaneous adipose tissue of CD36(-/-) and WT mice after 6 weeks on HFD. Basal lipolysis and insulin-inhibited lipolysis were investigated in gonadal adipose tissue. RESULTS: CD36(-/-) mice showed a reduction in adipocyte size in all fat pads. Gonadal adipose tissue also showed a lower total number of adipocytes because of a lower number of very small adipocytes (diameter <50 µm). This was accompanied by an increased pool of preadipocytes, which suggests that CD36-deficiency reduces the capacity of preadipocytes to become adipocytes. Regarding lipolysis, in adipose tissue from CD36(-/-) mice, cAMP levels were increased and both basal and 8-bromo-cAMP stimulated lipolysis were higher. However, insulin-mediated inhibition of lipolysis was more potent in CD36(-/-) mice. CONCLUSIONS: These results indicate that during fat depot expansion, CD36-deficiency negatively affects preadipocyte recruitment and that in mature adipocytes, CD36-deficiency is associated with increased basal lipolysis and insulin responsiveness.


Assuntos
Adipócitos/fisiologia , Antígenos CD36/fisiologia , Lipólise/fisiologia , 8-Bromo Monofosfato de Adenosina Cíclica/metabolismo , Tecido Adiposo/metabolismo , Animais , Antígenos CD36/deficiência , Diferenciação Celular , Tamanho Celular , Dieta Hiperlipídica/efeitos adversos , Ácidos Graxos/metabolismo , Insulina/metabolismo , Fígado/citologia , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Obesidade/metabolismo , Triglicerídeos/metabolismo
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