Jan Glatz

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Protein-mediated Fatty Acid Uptake in the Heart

Current Cardiology Reviews, Feb 1, 2008

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Assessment of AMPK-Stimulated Cellular Long-Chain Fatty Acid and Glucose Uptake

Springer eBooks, 2018

or visit the DOI to the publisher's website. • The final author version and the galley proof are ... more or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User

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Assessment of AMPK-Stimulated Cellular Long-Chain Fatty Acid and Glucose Uptake

Methods in molecular biology, 2018

Here we describe an assay for simultaneous measurement of cellular uptake rates of long-chain fat... more Here we describe an assay for simultaneous measurement of cellular uptake rates of long-chain fatty acids (LCFA) and glucose that can be applied to cells in suspension. The uptake assay includes the use of radiolabeled substrates at such concentrations and incubation periods that exact information is provided about unidirectional uptakes rates. Cellular uptake of both substrates is under regulation of AMPK. The underlying mechanism includes the translocation of LCFA and glucose transporters from intracellular membrane compartments to the cell surface, leading to an increase in substrate uptake. In this chapter, we explain the principles of the uptake assay before detailing the exact procedure. We also provide information of the specific LCFA and glucose transporters subject to AMPK-mediated subcellular translocation. Finally, we discuss the application of AMPK inhibitors and activators in combination with cellular substrate uptake assays.

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Fasting-induced changes in the expression of genes controlling substrate metabolism in the rat heart

Journal of Lipid Research, 2001

During fasting, when overall metabolism changes, the contribution of glucose and fatty acids (FA)... more During fasting, when overall metabolism changes, the contribution of glucose and fatty acids (FA) to cardiac energy production alters as well. Here, we examined if the heart is able to adapt to such fasting-induced changes by modulation of its gene expression. Rats were fed ad libitum or fasted for 46 h, resulting in reduced circulating glucose levels and a 3-fold rise in FA. Besides changes in the cardiac activity or content of proteins involved in glucose or FA metabolism, mRNA levels also altered. The cardiac expression of genes coding for glucose-handling proteins (glucose transporter GLUT4, hexokinase I and II) was up to 70% lower in fasted than in fed rats. In contrast, the mRNA levels of various genes involved in FA transport and metabolism (FA translocase/CD36, muscle-type carnitine palmitoyl transferase 1, long-chain acyl-CoA dehydrogenase) and of the uncoupling protein UCP-3 increased over 50% in hearts of fasted rats. Surprisingly, mRNA levels of the fatty acidactivated transcription factors PPAR ␣ and PPAR ␤ / ␦ were reduced in hearts of fasted rats, whereas in livers, fasting led to a marked rise in PPAR ␣ mRNA. Reducing FA levels by nicotinic acid administration during the final 8 h of fasting did not affect the expression of the majority of metabolic genes, but totally abolished the induction of UCP-3. In conclusion, the adult rat heart responds to changes in nutritional status, as provoked by 46 h fasting, through adjustment of glucose as well as FA metabolism at the level of gene expression. -Van der Lee, K.

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Protein kinase-D1 overexpression prevents lipid-induced cardiac insulin resistance

Journal of Molecular and Cellular Cardiology, 2014

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CD36 Displays Features of a Lipid-Sensor Involved in Chylomicron Processing in the Rodent Small Intestine

Atherosclerosis Supplements, 2010

International audienceThe membrane glycoprotein CD36 binds nanomolar concentrations of long-chain... more International audienceThe membrane glycoprotein CD36 binds nanomolar concentrations of long-chain fatty acids (LCFA) and is highly expressed on the luminal surface of enterocytes. CD36 deficiency reduces chylomicron production through unknown mechanisms.In this report, we provide novel insights into the potential underlying mechanisms. Our in vivo data demonstrated that CD36 gene deletion in mice did not affect LCFA uptake and their subsequent esterification into triglycerides by the intestinal mucosa at micellar LCFA concentrations prevailing in the intestine. In rodents, CD36 protein early disappeared from the luminal side of intestinal villi during the post-prandial period but only when the diet contained lipids. This drop was significant 1 h after a lipid supply and was associated with an ubiquitination of CD36 as reported during the ligand receptor desensitization process. Using CHO cells expressing CD36, it is shown that the digestion products, LCFA and diglycerides, triggered the CD36 ubiquitination. In vivo treatment with the proteasome inhibitor MG132 prevented the lipid-mediated degradation of CD36 and the up-regulation of L-FABP, a key gene implicated in the formation and secretion of large chylomicrons. Since the L-FABP up-regulation by lipids remained abolished in CD36-null mice with and without MG132, CD36 degradation appears to be linked to the chylomicron formation.Therefore, intestinal CD36 displays features of a lipid sensor involving in the adaptation of enterocyte metabolism to the post-prandial lipid challenge by producing large triglyceride-rich lipoproteins rapidly cleared in blood. This finding raises the possibility of alternative therapeutic approaches to reduce the post-prandial hypertriglyceridemia and prevent cardiovascular risks

Fatty Acid- and Cholesterol Transporter Protein Expression along the Human Intestinal Tract

Atherosclerosis Supplements, 2010

Background: Protein distribution profiles along the human intestinal tract of transporters involv... more Background: Protein distribution profiles along the human intestinal tract of transporters involved in the absorption of cholesterol and long-chain fatty acids (LCFA) have been scarcely evaluated. Methodology/Principal Findings: In post-mortem samples from 11 subjects, intestinal transporter distribution profiles were determined via Western Blot. Differences in transporter protein levels were statistically tested using ANOVA and Tukey's Post Hoc comparisons. Levels in all segments were expressed relative to those in duodenum. Except for ABCG5 and FATP4, levels (mean6SEM) were the highest in the ileum. For ABCA1, ileal levels (1.8060.26) differed significantly from those in duodenum (P = 0.049) and proximal colon (0.9260.14; P = 0.029). ABCG8 levels in ileum (1.9160.30) differed from those in duodenum (P = 0.041) and distal colon (0.8460.22; P = 0.010) and jejunum (1.6460.26) tended to be higher than distal colon (0.8460.22; P = 0.087). Ileal NPC1L1 levels (2.5660.51) differed from duodenum levels (P = 0.019) and from distal colon (1.0960.22; P = 0.030). There was also a trend (P = 0.098) for higher jejunal (2.2360.37) than duodenal NPC1L1 levels. The levels of ABCG5 did not correlate with those of ABCG8. FAT/CD36 levels in ileum (2.0360.42) differed from those in duodenum (P = 0.017), and proximal and distal colon (0.8960.13 and 0.9760.15 respectively; P = 0.011 and P = 0.014). FABPpm levels in ileum (1.0460.13) differed from proximal (0.6460.07; P = 0.026) and distal colon (0.6660.09; P = 0.037). Conclusions/Significance: The distribution profiles showed a bell-shape pattern along the GI-tract with the highest levels in ileum for ABCA1, ABCG8, NPC1L1, FATCD36 and FABPm, suggesting a prominent role for ileum in transporter-mediated uptake of cholesterol and LCFAs.

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Protein-mediated Fatty Acid Uptake in the Heart

Current Cardiology Reviews, 2008

Long chain fatty acids (LCFAs) provide 70-80% of the energy for cardiac contractile activity. LCF... more Long chain fatty acids (LCFAs) provide 70-80% of the energy for cardiac contractile activity. LCFAs are also essential for many other cellular functions, such as transcriptional regulation of proteins involved in lipid metabolism, modulation of intracellular signalling pathways, and as substrates for membrane constituents. When LCFA uptake exceeds the capacity for their cardiac utilization, the intracellular lipids accumulate and are thought to contribute to contractile dysfunction, arrhythmias, cardiac myocyte apoptosis and congestive heart failure. Moreover, increased cardiac myocyte triacylglycerol, diacylglycerol and ceramide depots are cardinal features associated with obesity and type 2 diabetes. In recent years considerable evidence has accumulated to suggest that, the rate of entry of long chain fatty acids (LCFAs) into the cardiac myocyte is a key factor contributing to a) regulating cardiac LCFA metabolism and b) lipotoxicity in the obese and diabetic heart. In the present review we i) examine the evidence indicating that LCFA transport into the heart involves a protein-mediated mechanism, ii) discuss the proteins involved in this process, including FAT/CD36, FABPpm and FATP1, iii) discuss the mechanisms involved in regulating LCFA transport by some of these proteins (including signaling pathways), as well as iv) the possible interactions of these proteins in regulating LCFA transport into the heart. In addition, v) we discuss how LCFA transport and transporters are altered in the obese/diabetic heart.

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Creatinine clearance and viability biomarkers of machine perfused non-heart-beating donors: is there a correlation?

Transplantation Proceedings, 2003

CD36 as a target to prevent cardiac lipotoxicity and insulin resistance

Prostaglandins, Leukotrienes and Essential Fatty Acids, 2013

The fatty acid transporter and scavenger receptor CD36 is increasingly being implicated in the pa... more 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.

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Membrane Fatty Acid Transporters as Regulators of Lipid Metabolism: Implications for Metabolic Disease

Physiological Reviews, 2010

Long-chain fatty acids and lipids serve a wide variety of functions in mammalian homeostasis, par... more Long-chain fatty acids and lipids serve a wide variety of functions in mammalian homeostasis, particularly in the formation and dynamic properties of biological membranes and as fuels for energy production in tissues such as heart and skeletal muscle. On the other hand, long-chain fatty acid metabolites may exert toxic effects on cellular functions and cause cell injury. Therefore, fatty acid uptake into the cell and intracellular handling need to be carefully controlled. In the last few years, our knowledge of the regulation of cellular fatty acid uptake has dramatically increased. Notably, fatty acid uptake was found to occur by a mechanism that resembles that of cellular glucose uptake. Thus, following an acute stimulus, particularly insulin or muscle contraction, specific fatty acid transporters translocate from intracellular stores to the plasma membrane to facilitate fatty acid uptake, just as these same stimuli recruit glucose transporters to increase glucose uptake. This reg...

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Regulation of cardiac long-chain fatty acid and glucose uptake by translocation of substrate transporters

Pflügers Archiv, 2004

Cardiac uptake of long-chain fatty acids (FA) is mediated predominantly by two membrane-associate... more Cardiac uptake of long-chain fatty acids (FA) is mediated predominantly by two membrane-associated proteins, the 43-kDa plasma membrane fatty acid-binding protein (FABPpm) and the 88-kDa fatty acid translocase/CD36 (FAT/CD36). While FABPpm is present constitutively in the sarcolemma, FAT/CD36 is recycled between an intracellular membrane compartment and the sarcolemma. Since the amount of sarcolemmal FAT/CD36 is a major determinant of cellular FA uptake, understanding of the regulation of its recycling is likely to provide new insights into altering substrate preference of the heart. FAT/CD36 recycling displays a remarkable similarity with that of the two glucose transporters (GLUT) in the heart, GLUT1 and GLUT4. Translocation of all three transporters is induced by insulin and by contraction, which stimuli activate distinct signalling cascades. The insulin pathway involves phosphatidylinositol-3 kinase (PI3K) whilst the contraction pathway is dependent on AMP-activated protein kinase (AMPK). For the identification of additional protein components involved in the regulation of FAT/CD36 recycling, valuable lessons can be learned from GLUT1 and GLUT4 recycling. Especially GLUT4 recycling is an intensively studied process in which a number of signalling proteins, both upstream and downstream from PI3 K and AMPK, have been identified, as well as proteins that are part of the translocation machinery involving Rab GTPases and soluble N-ethylmaleimide attachment protein receptors (SNAREs). Comparison of the magnitude of the effects of insulin and contraction on substrate uptake and on transporter appearance in the sarcolemma have revealed that FAT/CD36 recycling resembles GLUT1 recycling more closely than that of GLUT4. This pinpoints the recycling compartment and excludes a pre-endosomal storage compartment as the intracellular storage site for FAT/CD36. Further research will probably establish whether FAT/CD36 translocation is (partly) coupled to that of one or both GLUTs or, alternatively, whether it is a distinct process that also can be induced independently of GLUT1 or GLUT4 movement. In the latter case, a unique set of proteins would be dedicated to FAT/CD36 recycling, which would then provide an attractive target for manipulating cardiac substrate preference.

Fabp and MB - an Ideal Pair of Early Plasma Markers to Diagnose Exercise-Induced Muscle Injury

Medicine & Science in Sports & Exercise, 2003

Monoclonal antibodies to human heart fatty acid-binding protein

Journal of Immunological Methods, 1995

Heart-type fatty acid-binding protein (H-FABP), a 15 kDa non-enzymatic protein, which is abundant... more Heart-type fatty acid-binding protein (H-FABP), a 15 kDa non-enzymatic protein, which is abundantly present in heart and some skeletal muscles, was recently found to be a useful plasma marker for acute myocardial infarction. The BIAcore biosensor technology was used to raise and characterize a panel of 13 monoclonal antibodies against human H-FABP which did not crossreact with other FABP types of human origin. The kinetics of association and dissociation between FABP and the monoclonal antibodies was studied. By pairwise mapping several distinct epitopes could be identified.

Luminal Lipid Regulates CD36 Levels and Downstream Signaling to Stimulate Chylomicron Synthesis

Journal of Biological Chemistry, 2011

The membrane glycoprotein CD36 binds nanomolar concentrations of long chain fatty acids (LCFA) an... more The membrane glycoprotein CD36 binds nanomolar concentrations of long chain fatty acids (LCFA) and is highly expressed on the luminal surface of enterocytes. CD36 deficiency reduces chylomicron production through unknown mechanisms. In this report, we provide novel insights into some of the underlying mechanisms. Our in vivo data demonstrate that CD36 gene deletion in mice does not affect LCFA uptake and subsequent esterification into triglycerides by the intestinal mucosa exposed to the micellar LCFA concentrations prevailing in the intestine. In rodents, the CD36 protein disappears early from the luminal side of intestinal villi during the postprandial period, but only when the diet contains lipids. This drop is significant 1 h after a lipid supply and associates with ubiquitination of CD36. Using CHO cells expressing CD36, it is shown that the digestion products LCFA and diglycerides trigger CD36 ubiquitination. In vivo treatment with the proteasome inhibitor MG132 prevents the lipid-mediated degradation of CD36. In vivo and ex vivo, CD36 is shown to be required for lipid activation of ERK1/2, which associates with an increase of the key chylomicron synthesis proteins, apolipoprotein B48 and microsomal triglyceride transfer protein. Therefore, intestinal CD36, possibly through ERK1/2-mediated signaling, is involved in the adaptation of enterocyte metabolism to the postprandial lipid challenge by promoting the production of large triglyceride-rich lipoproteins that are rapidly cleared in the blood. This suggests that CD36 may be a therapeutic target for reducing the postprandial hypertriglyceridemia and associated cardiovascular risks.

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Detection of brain injury by fatty acid-binding proteins

Clinical Chemistry and Laboratory Medicine (CCLM), 2005

The rapid detection of brain injury (neuronal damage in general) is an important parameter in the... more The rapid detection of brain injury (neuronal damage in general) is an important parameter in the management of cerebrovascular accidents, especially in hemorrhagic and/or ischemic events. Two types of 15-kDa cytoplasmic fatty acid-binding proteins (FABPs), brain-type FABP and heart-type FABP, have recently been postulated as novel markers for brain injury detection. Here we review the possible roles of these FABPs as rapid diagnostic markers for the detection of brain injury due to cerebrovascular accident, trauma or neurodegenerative diseases. The occurrence of brain- and heart-type FABPs in segments of the human brain is also described. Although only limited amounts of data are available, brain- and heart-type FABPs show higher sensitivities and specificities than protein S100 and neuron specific enolase in the rapid detection of brain injury in stroke, trauma and neurodegenerative diseases.

Fatty acid-binding proteins as plasma markers of tissue injury

Clinica Chimica Acta, 2005

One of the novel and promising plasma markers for detection of tissue injury is the family of 15 ... more One of the novel and promising plasma markers for detection of tissue injury is the family of 15 kDa cytoplasmic fatty acid-binding proteins of which various tissue-specific types occur. The present status of heart-type fatty acid-binding protein (H-FABP) as a diagnostic and prognostic marker for acute and chronic cardiac injury, as well as the preliminary diagnostic use of other types of FABP for detecting injury in other organs, is reviewed. This review is based on an overview of the literature on clinical diagnostics of various forms of organ injury, and uses additional literature on physiological aspects relevant for the interpretation of plasma marker concentrations. H-FABP not only proves to be an excellent early marker for cardiac injury in acute coronary syndromes, but also allows detection of minor myocardial injury in heart failure and unstable angina. Preliminary results indicate that sensitivity, rule-out power and prognostic value of H-FABP in cardiac injury surpass the performance of the standard early marker myoglobin. The liver only contains liver-type FABP (L-FABP), but co-expression of H-FABP and L-FABP occurs in the kidney. Similarly, intestinal-type FABP (I-FABP) and L-FABP are found in intestines, and brain-type FABP (B-FABP) and H-FABP occur in the brain. Preliminary but promising applications of these proteins have been demonstrated for liver rejection, viability selection of kidneys from non-heart-beating donors (NHBD), inflammatory and ischemic bowel disease, traumatic brain injury and in the prevention of muscle injury in trained athletes. Further study of the diagnostic and prognostic use of various FABP types is warranted, but their clinical application will require further commercialization of automated and rapid assays.

Plasma heart-type fatty acid binding protein is superior to troponin and myoglobin for rapid risk stratification in acute pulmonary embolism

Clinica Chimica Acta, 2006

Irreversible right ventricular (RV) failure with myocardial damage may precipitate fatal outcome ... more Irreversible right ventricular (RV) failure with myocardial damage may precipitate fatal outcome in acute pulmonary embolism (APE). Cytoplasmic heart-type fatty acid binding protein (H-FABP) is a sensitive and specific biomarker of myocardial damage. We assessed which biomarker of myocardial damage or RV stretching is the most useful for short-term risk stratification in APE. We analyzed 77 patients (51 F, 26 M) aged 65.3+/-16.0 years with confirmed APE. On admission, systemic blood pressure and transthoracic echocardiography (for RV overload) were recorded and plasma concentrations of myoglobin (Mb), cardiac troponin T (cTnT), N-terminal fragment of proBNP (NT-proBNP) and H-FABP were evaluated. Fifteen (19.5%) patients died and 24 (31.2%) experienced complicated clinical course (CCC)-death/thrombolysis/cardiopulmonary resuscitation/intravenous vasopressors. Hazard ratio analysis demonstrated that plasma H-FABP, Mb, cTnT and NT-proBNP concentrations predicted fatal outcome. When only APE-related deaths were considered, plasma H-FABP concentrations indicated fatal outcome. Multivariate hazard ratio analysis revealed H-FABP as the only 30-day mortality predictor (HR 1.02 CI 95% 1.01-1.05). H-FABP measured on admission is useful for short-term risk stratification in APE. It appears to be superior to cTnT, NT-proBNP and Mb in the prediction of 30-day APE-related mortality.

Regulation of sarcolemmal glucose and fatty acid transporters in cardiac disease

Cardiovascular Research, 2008

Circulating long-chain fatty acids (LCFA) and glucose are the main sources for energy production ... more Circulating long-chain fatty acids (LCFA) and glucose are the main sources for energy production in the heart. In the healthy heart the ratio of glucose and LCFA oxidation is sensitively balanced and chronic alterations in this substrate mix are closely associated with cardiac dysfunction. While it has been accepted for several years that cardiac glucose uptake is mediated by facilitated transport, i.e. by means of the glucose transport proteins GLUT1 and GLUT4, only in the last few years it has become clear that proteins with high-affinity binding sites to LCFA, referred to as LCFA transporters, are responsible for bulk LCFA uptake. Similar to the GLUTs, the LCFA transporters CD36 and FABP pm can be recruited from an intracellular storage compartment to the sarcolemma to increase the rate of substrate uptake. Permanent relocation of LCFA transporters, mainly CD36, from intracellular stores to the sarcolemma is accompanied by accumulation of lipids and lipid metabolites in the heart. As a consequence, insulin signalling and glucose utilization are impaired, leading to decreased contractile activity of the heart. These observations underline the particular role and interplay of substrate carriers for glucose and LCFA in modulating cardiac metabolism, and the development of heart failure. The signalling and trafficking pathways and subcellular machinery regulating translocation of glucose and LCFA transporters are beginning to be unravelled. More knowledge on substrate transporter recycling, especially the similarities and differences between glucose and LCFA transporters, is expected to enable novel therapies aimed at changing the subcellular distribution of glucose and LCFA transporters, thereby manipulating the substrate preference of the diseased heart to help restore cardiac function.

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Development of a displacement immunoassay for human heart-type fatty acid-binding protein in plasma: the basic conditions

Biosensors and Bioelectronics, 2003

To risk-stratify patients with chest pain who are admitted to emergency rooms and for whom initia... more To risk-stratify patients with chest pain who are admitted to emergency rooms and for whom initial evaluation is not conclusive, the use of cardiac markers has become a standard procedure. A recently introduced early plasma marker for acute myocardial infarction (AMI) is the 14.5-kDa cytoplasmic heart-type fatty acid-binding protein (FABP). To fully exploit its early release from injured myocardium, a rapid method for repeated measurements or continuous monitoring of FABP in plasma is desirable. Such an on-line method could be an immunosensor based on displacement. The aim of the present study was to further investigate the principles underlying the displacement assay of FABP, both in buffer and in plasma. Batches of sepharose-bound FABP were loaded with an antibody-horseradish peroxidase (HRP) conjugate (anti-FABP). Continuous measurement of FABP was mimicked by repeated addition of FABP containing solutions followed by several washing steps. In the presence of free FABP the antibody-HRP complex dissociated and was subsequently quantified. Significant displacement in the presence of free FABP was observed in both buffer and human plasma. Anti-FABP could be intermittently displaced in the same batch, for at least 9 h, and the displacement was concentration-dependent. These results show the feasibility of a sensor based on the displacement principle to be used for the diagnosis of AMI in emergency medicine.

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