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Lester R. Drewes - One of the best experts on this subject based on the ideXlab platform.

  • novel n n dialkyl cyanocinnamic acids as Monocarboxylate Transporter 1 and 4 inhibitors
    Oncotarget, 2019
    Co-Authors: Sravan K Jonnalagadda, Grady L Nelson, Venkatram R Mereddy, Conor T Ronayne, Lucas N Solano, Jon N Rumbley, Jon M Holy, Lester R. Drewes
    Abstract:

    // Shirisha Jonnalagadda 1 , Sravan K. Jonnalagadda 1 , Conor T. Ronayne 1 , Grady L. Nelson 1 , Lucas N. Solano 1 , Jon Rumbley 1, 2 , Jon Holy 1, 3 , Venkatram R. Mereddy 1, 2, 4 and Lester R. Drewes 1, 3 1 Integrated Biosciences Graduate Program, University of Minnesota, Duluth, MN 55812, USA 2 Department of Pharmacy Practice & Pharmaceutical Sciences, University of Minnesota, Duluth, MN 55812, USA 3 Department of Biomedical Sciences, Medical School Duluth, University of Minnesota, Duluth, MN 55812, USA 4 Department of Chemistry and Biochemistry, University of Minnesota, Duluth, MN 55812, USA Correspondence to: Lester R. Drewes, email: ldrewes@d.umn.edu Venkatram R. Mereddy, email: vmereddy@d.umn.edu Keywords: Monocarboxylate Transporter 1 inhibitor; Monocarboxylate Transporter 4 inhibitor; 2-alkoxy- N,N -dialkyl cyanocinnamic acid; cancer; metabolism Received: December 02, 2018      Accepted: February 22, 2019      Published: March 22, 2019 ABSTRACT Potent and dual Monocarboxylate Transporter (MCT) 1 and 4 inhibitors have been developed for the first time as potential anticancer agents based on α-cyanocinnamic acid structural template. Candidate inhibitors 1–9 have been evaluated for in vitro cell proliferation against MCT1 and MCT4 expressing cancer cell lines. Potential MCT1 and MCT4 binding interactions of the lead compound 9 have been studied through homology modeling and molecular docking prediction. In vitro effects on extracellular flux via glycolysis and mitochondrial stress tests suggest that candidate compounds 3 and 9 disrupt glycolysis and OxPhos efficiently in MCT1 expressing colorectal adenocarcinoma WiDr and MCT4 expressing triple negative breast cancer MDA-MB-231 cells. Fluorescence microscopy analyses in these cells also indicate that compound 9 is internalized and concentrated near mitochondria. In vivo tumor growth inhibition studies in WiDr and MDA-MB-231 xenograft tumor models in mice indicate that the candidate compound 9 exhibits a significant single agent activity.

  • coumarin carboxylic acids as Monocarboxylate Transporter 1 inhibitors in vitro and in vivo studies as potential anticancer agents
    Bioorganic & Medicinal Chemistry Letters, 2016
    Co-Authors: Shirisha Gurrapu, Sravan K Jonnalagadda, Mohammad A Alam, Grady L Nelson, Conor T Ronayne, Lucas N Solano, Erica A Lueth, Lester R. Drewes, Venkatram R Mereddy
    Abstract:

    Novel N,N-dialkyl carboxy coumarins have been synthesized as potential anticancer agents via inhibition of Monocarboxylate Transporter 1 (MCT1). These coumarin carboxylic acids have been evaluated for their in vitro MCT1 inhibition, MTT cancer cell viability, bidirectional Caco-2 cell permeability, and stability in human and liver microsomes. These results indicate that one of the lead candidate compounds 4a has good absorption, metabolic stability, and a low drug efflux ratio. Systemic toxicity studies with lead compound 4a in healthy mice demonstrate that this inhibitor is well tolerated based on zero animal mortality and normal body weight gains compared to the control group. In vivo tumor growth inhibition studies in mice show that the candidate compound 4a exhibits significant single agent activity in MCT1 expressing GL261-luc2 syngraft model but doesn’t show significant activity in MCT4 expressing MDA-MB-231 xenograft model, indicating the selectivity of 4a for MCT1 expressing tumors.

  • Monocarboxylate Transporter 1 inhibitors as potential anticancer agents
    ACS Medicinal Chemistry Letters, 2015
    Co-Authors: Shirisha Gurrapu, Sravan K Jonnalagadda, Mohammad A Alam, Grady L Nelson, Mary Sneve, Lester R. Drewes, Venkatram R Mereddy
    Abstract:

    Potent Monocarboxylate Transporter 1 inhibitors (MCT1) have been developed based on α-cyano-4-hydroxycinnamic acid template. Structure–activity relationship studies demonstrate that the introduction of p-N, N-dialkyl/diaryl, and o-methoxy groups into cyanocinnamic acid has maximal MCT1 inhibitory activity. Systemic toxicity studies in healthy ICR mice with few potent MCT1 inhibitors indicate normal body weight gains in treated animals. In vivo tumor growth inhibition studies in colorectal adenocarcinoma (WiDr cell line) in nude mice xenograft models establish that compound 27 exhibits single agent activity in inhibiting the tumor growth.

  • expression of Monocarboxylate Transporter mct1 in normal and neoplastic human cns tissues
    Neuroreport, 2001
    Co-Authors: Kent M Froberg, David Z. Gerhart, Bradley E. Enerson, Carlos Manivel, Manuel Guzmanpaz, Nicole Seacotte, Lester R. Drewes
    Abstract:

    Expression of Monocarboxylate Transporter MCT1 was studied in archival tissues from human CNS using antibodies to the carboxyl-terminal end of MCT1. Sections of neocortex, hippocampus and cerebellum of brains from 10 adult autopsy patients who died from other than CNS disease, and from archival surgical biopsy specimens of 83 primary CNS and eight non-CNS tumors were studied. MCT1 immunoreactivity was present in microvessels and, ependymocytes of normal CNS tissues similar to that reported for MCT1 expression in rat brains. MCT1 immunoreactivity was strongest in ependymomas, hemangioblastomas and high grade glial neoplasms, and weakest in low grade gliomas. Increased MCT1 expression in high grade glial neoplasms may provide a potential therapeutic target for treatment of some CNS neoplasms.

  • Diet-induced ketosis increases Monocarboxylate Transporter (MCT1) levels in rat brain.
    Neurochemistry international, 2001
    Co-Authors: Richard L. Leino, David Z. Gerhart, Bradley E. Enerson, Roman Duelli, Lester R. Drewes
    Abstract:

    Abstract Monocarboxylate Transporter (MCT1) levels in brains of adult Long–Evans rats on a high-fat (ketogenic) diet were investigated using light and electron microscopic immunocytochemical methods. Rats given the ketogenic diet (91% fat and 9% protein) for up to 6 weeks had increased levels of the Monocarboxylate Transporter MCT1 (and of the glucose Transporter GLUT1) in brain endothelial cells and neuropil compared to rats on a standard diet. In ketonemic rats, electron microscopic immunogold methods revealed an 8-fold greater MCT1 labeling in the brain endothelial cells at 4 weeks. Abluminal endothelial membranes were twice as heavily labeled as luminal membranes. In controls, luminal and abluminal labeling was not significantly different. The endothelial cytoplasmic compartment was sparsely labeled (

Luc Pellerin - One of the best experts on this subject based on the ideXlab platform.

  • reducing Monocarboxylate Transporter mct1 worsens experimental diabetic peripheral neuropathy
    Experimental Neurology, 2020
    Co-Authors: Mithilesh Kumar Jha, Xanthe Heifetz Ament, Luc Pellerin, Michael Polydefkis, Fang Yang, Ying Liu, Brett M Morrison
    Abstract:

    Diabetic peripheral neuropathy (DPN) is one of the most common complications in diabetic patients. Though the exact mechanism for DPN is unknown, it clearly involves metabolic dysfunction and energy failure in multiple cells within the peripheral nervous system. Lactate is an alternate source of metabolic energy that is increasingly recognized for its role in supporting neurons. The primary Transporter for lactate in the nervous system, Monocarboxylate Transporter-1 (MCT1), has been shown to be critical for peripheral nerve regeneration and metabolic support to neurons/axons. In this study, MCT1 was reduced in both sciatic nerve and dorsal root ganglia in wild-type mice treated with streptozotocin (STZ), a common model of type-1 diabetes. Heterozygous MCT1 null mice that developed hyperglycemia following STZ treatment developed a more severe DPN compared to wild-type mice, as measured by greater axonal demyelination, decreased peripheral nerve function, and increased numbness to innocuous low-threshold mechanical stimulation. Given that MCT1 inhibitors are being developed as both immunosuppressive and chemotherapeutic medications, our results suggest that clinical development in patients with diabetes should proceed with caution. Collectively, our findings uncover an important role for MCT1 in DPN and provide a potential lead toward developing novel treatments for this currently untreatable disease.

  • reducing Monocarboxylate Transporter mct1 worsens experimental diabetic peripheral neuropathy
    bioRxiv, 2020
    Co-Authors: Xanthe Heifetz Ament, Luc Pellerin, Michael Polydefkis, Fang Yang, Brett M Morrison
    Abstract:

    Abstract Diabetic peripheral neuropathy (DPN) is one of the most common complications in diabetic patients. Though the exact mechanism for DPN is unknown, it clearly involves metabolic dysfunction and energy failure in multiple cells within the peripheral nervous system (PNS). Lactate is an alternate source of metabolic energy that is increasingly recognized for its role in supporting neurons. The primary Transporter for lactate in the nervous system, Monocarboxylate Transporter-1 (MCT1), has been shown to be critical for peripheral nerve regeneration and metabolic support to neurons/axons. In this study, MCT1 was reduced in both sciatic nerve and dorsal root ganglia in wild-type mice treated with streptozotocin (STZ), a common model of type-1 diabetes. Heterozygous MCT1 null mice treated with STZ developed a more severe DPN compared to wild-type mice, as measured by greater axonal demyelination, decreased peripheral nerve function, and increased numbness to innocuous low-threshold mechanical stimulation. Given that MCT1 inhibitors are being developed as both immunosuppressive and chemotherapeutic medications, our results suggest that clinical development in patients with diabetes should proceed with caution. Collectively, our findings uncover an important role for MCT1 in DPN and provide a potential lead toward developing novel treatments for this currently untreatable disease.

  • Nitric oxide induces the expression of the Monocarboxylate Transporter MCT4 in cultured astrocytes by a cGMP-independent transcriptional activation.
    Glia, 2011
    Co-Authors: Fabrice Marcillac, Britta Brix, Cendrine Repond, Olaf Jöhren, Luc Pellerin
    Abstract:

    The Monocarboxylate Transporter MCT4 is a proton-linked carrier particularly important for lactate release from highly glycolytic cells. In the central nervous system, MCT4 is exclusively expressed by astrocytes. Surprisingly, MCT4 expression in primary cultures of mouse cortical astrocytes is conspicuously low, suggesting that an external, nonastrocytic signal is necessary to obtain the observed pattern of expression in vivo. Here, we demonstrate that nitric oxide (NO), delivered by various NO donors, time- and dose-dependently induces MCT4 expression in cultured cortical astrocytes both at the mRNA and protein levels. In contrast, NO does not enhance the expression of MCT1, the other astrocytic Monocarboxylate Transporter. The transcriptional effect of NO is not mediated by a cGMP-dependent mechanism as shown by the absence of effect of a cGMP analog or of a selective guanylate cyclase inhibitor. NO causes an increase in astrocytic lactate transport capacity which requires the enhancement of MCT4 expression as both are prevented by the use of a specific siRNA against MCT4. In addition, cumulated lactate release by astrocytes over a period of 24 h was also enhanced by NO treatment. Our data suggest that NO represents a putative intercellular signal to control MCT4 expression in astrocytes and in doing so, to facilitate lactate transfer to other surrounding cell types in the central nervous system. © 2011 Wiley-Liss, Inc.

  • Distribution of the Monocarboxylate Transporter MCT2 in human cerebral cortex: An immunohistochemical study
    Brain research, 2008
    Co-Authors: Oriana Chiry, Pierre J Magistretti, William N. Fishbein, Natalya Merezhinskaya, Stephanie Clarke, Ralf A. W. Galuske, Luc Pellerin
    Abstract:

    The Monocarboxylate Transporter MCT2 belongs to a large family of membrane proteins involved in the transport of lactate, pyruvate and ketone bodies. Although its expression in rodent brain has been well documented, the presence of MCT2 in the human brain has been questioned on the basis of low mRNA abundance. In this study, the distribution of the Monocarboxylate Transporter MCT2 has been investigated in the cortex of normal adult human brain using an immunohistochemical approach. Widespread neuropil staining in all cortical layers was observed by light microscopy. Such a distribution was very similar in three different cortical areas investigated. At the cellular level, the expression of MCT2 could be observed in a large number of neurons, in fibers both in grey and white matter, as well as in some astrocytes, mostly localized in layer I and in the white matter. Double staining experiments combined with confocal microscopy confirmed the neuronal expression but also suggested a preferential postsynaptic localization of synaptic MCT2 expression. A few astrocytes in the grey matter appeared to exhibit MCT2 labelling but at low levels. Electron microscopy revealed strong MCT2 expression at asymmetric synapses in the postsynaptic density and also within the spine head but not in the presynaptic terminal. These data not only demonstrate neuronal MCT2 expression in human, but since a portion of it exhibits a distinct synaptic localization, it further supports a putative role for MCT2 in adjustment of energy supply to levels of activity.

  • MCT2 is a Major Neuronal Monocarboxylate Transporter in the Adult Mouse Brain
    Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism, 2002
    Co-Authors: Karin Pierre, Pierre J Magistretti, Luc Pellerin
    Abstract:

    Although previous Northern blot and in situ hybridization studies suggested that neurons express the Monocarboxylate Transporter MCT2, subsequent immunohistochemical analyzes either failed to confirm the presence of this Transporter or revealed only a low density of immunolabeled neuronal processes in vivo. The authors report that appropriate section pretreatment (brief warming episode or proteinase K exposure) leads to extensive labeling of the neuropil, which appears as tiny puncta throughout the whole mouse brain. In addition, intense MCT2 immunoreactivity was found in cerebellar Purkinje cell bodies and their processes, on mossy fibers in the cerebellum, and on sensory fibers in the brainstem. Double immunofluorescent labeling with appropriate markers and observation with epifluorescence and confocal microscopy did not show extensive colocalization of MCT2 immunoreactivity with presynaptic or postsynaptic elements, but colocalization could be observed occasionally in the cortex with the postsynaptic density protein PSD95. Observations made at the electron microscopic level in the cortex corroborated these results and showed that MCT2 immunoreactivity was associated with wide membrane segments of neuronal processes. These data provide convincing evidence that MCT2 represents a major neuronal Monocarboxylate Transporter in the adult mouse brain, and further suggest that mature neurons could use Monocarboxylates such as lactate as additional energy substrates.

Andrew P. Halestrap - One of the best experts on this subject based on the ideXlab platform.

  • the Monocarboxylate Transporter family role and regulation
    Iubmb Life, 2012
    Co-Authors: Andrew P. Halestrap, Marieangela C Wilson
    Abstract:

    Monocarboxylate Transporter (MCT) isoforms 1-4 catalyze the proton-linked transport of Monocarboxylates such as L-lactate across the plasma membrane, whereas MCT8 and MCT10 are thyroid hormone and aromatic amino acid Transporters, respectively. The importance of MCTs is becoming increasingly evident as their extensive physiological and pathological roles are revealed. MCTs 1-4 play essential metabolic roles in most tissues with their distinct properties, expression profile, and subcellular localization matching the particular metabolic needs of a tissue. Important metabolic roles include energy metabolism in the brain, skeletal muscle, heart, tumor cells, and T-lymphocyte activation, gluconeogenesis in the liver and kidney, spermatogenesis, bowel metabolism of short-chain fatty acids, and drug transport. MCT8 is essential for thyroid hormone transport across the blood-brain barrier. Genetic perturbation of MCT function may be involved in disease states such as pancreatic β-cell malfunction (inappropriate MCT1 expression), chronic fatigue syndromes (impairment of muscle MCT function), and psychomotor retardation (MCT8 mutation). MCT expression can be regulated at both the transcriptional and post-transcriptional levels. Of particular importance is the upregulation of muscle MCT1 expression in response to training and MCT4 expression in response to hypoxia. The latter is mediated by hypoxia inducible factor 1α and often observed in tumor cells that rely almost entirely on glycolysis for their energy provision. The recent discovery of potent and specific MCT1 inhibitors that prevent proliferation of T-lymphocytes confirms that MCTs may be promising pharmacological targets including for cancer chemotherapy.

  • identification of Monocarboxylate Transporter 8 as a specific thyroid hormone Transporter
    Journal of Biological Chemistry, 2003
    Co-Authors: Edith C. H. Friesema, Andrew P. Halestrap, Jocelyn Manning E Fox, Sumita Ganguly, Amal Abdalla, Theo J. Visser
    Abstract:

    Transport of thyroid hormone across the cell membrane is required for its action and metabolism. Recently, a T-type amino acid Transporter was cloned which transports aromatic amino acids but not iodothyronines. This Transporter belongs to the Monocarboxylate Transporter (MCT) family and is most homologous with MCT8 (SLC16A2). Therefore, we cloned rat MCT8 and tested it for thyroid hormone transport in Xenopus laevis oocytes. Oocytes were injected with rat MCT8 cRNA, and after 3 days immunofluorescence microscopy demonstrated expression of the protein at the plasma membrane. MCT8 cRNA induced an approximately 10-fold increase in uptake of 10 nM 125I-labeled thyroxine (T4), 3,3',5-triiodothyronine (T3), 3,3',5'-triiodothyronine (rT3) and 3,3'-diiodothyronine. Because of the rapid uptake of the ligands, transport was only linear with time for <4 min. MCT8 did not transport Leu, Phe, Trp, or Tyr. [125I]T4 transport was strongly inhibited by L-T4, D-T4, L-T3, D-T3, 3,3',5-triiodothyroacetic acid, N-bromoacetyl-T3, and bromosulfophthalein. T3 transport was less affected by these inhibitors. Iodothyronine uptake in uninjected oocytes was reduced by albumin, but the stimulation induced by MCT8 was markedly increased. Saturation analysis provided apparent Km values of 2-5 microM for T4, T3, and rT3. Immunohistochemistry showed high expression in liver, kidney, brain, and heart. In conclusion, we have identified MCT8 as a very active and specific thyroid hormone Transporter.

  • Upregulation of the Cardiac Monocarboxylate Transporter MCT1 in a Rat Model of Congestive Heart Failure
    Circulation, 2001
    Co-Authors: Erlingur Johannsson, Linda H Bergersen, Andrew P. Halestrap, Per Kristian Lunde, Catherine Heddle, Ivar Sjaastad, Marion J. Thomas, Theodor W. Blackstad, Ole Petter Ottersen, Ole M. Sejersted
    Abstract:

    Background— Cardiac metabolism becomes more dependent on carbohydrates in congestive heart failure (CHF), and lactate may be used as an important respiratory substrate. Monocarboxylate Transporter ...

  • a novel postsynaptic density protein the Monocarboxylate Transporter mct2 is co localized with δ glutamate receptors in postsynaptic densities of parallel fiber purkinje cell synapses
    Experimental Brain Research, 2001
    Co-Authors: Linda H Bergersen, Andrew P. Halestrap, Marion J. Thomas, O Waerhaug, Johannes P Helm, Petter Laake, Andrew J Davies, Mariangela C Wilson, Ole Petter Ottersen
    Abstract:

    Confocal immunofluorescence microscopy showed strong Monocarboxylate Transporter 2 (MCT2) labeling of Purkinje cell bodies and punctate labeling in the molecular layer. By immunogold cytochemistry, it could be demonstrated that the MCT2 immunosignal was concentrated at postsynaptic densities of parallel fiber–Purkinje cell synapses. The distribution of MCT2 Transporters within the individual postsynaptic densities mimicked that of the δ2 glutamate receptor, as shown by use of two different gold-particle sizes. The MCT2 distribution was also compared with the distributions of other Monocarboxylate Transporters (MCT1 and MCT4). The MCT1 immunolabeling was localized in the endothelial cells, while MCT4 immunogold particles were associated with glial profiles, including those abutting the synaptic cleft of the parallel fiber-spine synapses. The postsynaptic density (PSD) molecules identified so far can be divided into five classes: receptors, their anchoring molecules, molecules involved in signal transduction, ion channels, and attachment proteins. Here, we provide evidence that this list of molecules must now be extended to comprise an organic molecule Transporter: the Monocarboxylate Transporter MCT2. The present data suggest that MCT2 has specific transport functions related to the synaptic cleft and that this Transporter may allow an influx of lactate derived from perisynaptic glial processes. The expression of MCT2 in synaptic membranes may allow energy supply to be tuned to the excitatory drive.

  • characterisation of human Monocarboxylate Transporter 4 substantiates its role in lactic acid efflux from skeletal muscle
    The Journal of Physiology, 2000
    Co-Authors: Jocelyn Manning E Fox, David Meredith, Andrew P. Halestrap
    Abstract:

    Monocarboxylate Transporter (MCT) 4 is the major Monocarboxylate Transporter isoform present in white skeletal muscle and is responsible for the efflux of lactic acid produced by glycolysis. Here we report the characterisation of MCT4 expressed in Xenopus oocytes. The protein was correctly targeted to the plasma membrane and rates of substrate transport were determined from the rate of intracellular acidification monitored with the pH-sensitive dye 2', 7'-bis-(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). In order to validate the technique, the kinetics of Monocarboxylate transport were measured in oocytes expressing MCT1. Km values determined for L-lactate, D-lactate and pyruvate of 4.4, > 60 and 2.1 mM, respectively, were similar to those determined previously in tumour cells. Comparison of the time course of [14C]lactate accumulation with the rate of intracellular acidification monitored with BCECF suggests that the latter reflects pH changes close to the plasma membrane associated with transport, whilst the former may include diffusion-limited movement of lactate into the bulk cytosol. Km values of MCT4 for these substrates were found to be 28, 519 and 153 mM, respectively, and for a range of other Monocarboxylates values were at least an order of magnitude higher than for MCT1. Vmax values appeared to be similar for all substrates. K0.5 values of MCT4 (determined at 30 mM L-lactate) for inhibition by alpha-cyano-4-hydroxycinnamate (991 microM), phloretin (41 microM), 5-nitro-2-(3-phenylpropylamino)benzoate (240 microM), p-chloromercuribenzene sulphonate (21 microM) and 3-isobutyl-1-methylxanthine (970 microM, partial inhibition) were also substantially higher than for MCT1. No inhibition of MCT4 by 2 mM 4,4'-diisothiocyanostilbene-2,2'-disulphonate was observed. The properties of MCT4 are consistent with published data on giant sarcolemmal vesicles in which MCT4 is the dominant MCT isoform, and are appropriate for the proposed role of MCT4 in mediating the efflux from the cell of glycolytically derived lactic acid but not pyruvate.

Joachim W. Deitmer - One of the best experts on this subject based on the ideXlab platform.

  • Integration of a ‘proton antenna’ facilitates transport activity of the Monocarboxylate Transporter MCT4
    FEBS Journal, 2017
    Co-Authors: Sina Ibne Noor, Joachim W. Deitmer, Jacques Pouysségur, Holger M. Becker
    Abstract:

    Monocarboxylate Transporters (MCTs) mediate the proton-coupled transport of high-energy metabolites like lactate and pyruvate and are expressed in nearly every mammalian tissue. We have shown previously that transport activity of MCT4 is enhanced by carbonic anhydrase II (CAII), which has been suggested to function as a 'proton antenna' for the Transporter. In the present study, we tested whether creation of an endogenous proton antenna by introduction of a cluster of histidine residues into the C-terminal tail of MCT4 (MCT4-6xHis) could facilitate MCT4 transport activity when heterologously expressed in Xenopus oocytes. Our results show that integration of six histidines into the C-terminal tail does indeed increase transport activity of MCT4 to the same extent as did coexpression of MCT4-WT with CAII. Transport activity of MCT4-6xHis could be further enhanced by coexpression with extracellular CAIV, but not with intracellular CAII. Injection of an antibody against the histidine cluster into MCT4-expressing oocytes decreased transport activity of MCT4-6xHis, while leaving activity of MCT4-WT unaltered. Taken together, these findings suggest that transport activity of the proton-coupled Monocarboxylate Transporter MCT4 can be facilitated by integration of an endogenous proton antenna into the Transporter's C-terminal tail.

  • Inhibition of Monocarboxylate Transporter by N-cyanosulphonamide S0859
    European journal of pharmacology, 2015
    Co-Authors: Hella Heidtmann, Holger M. Becker, Iván Ruminot, Joachim W. Deitmer
    Abstract:

    Abstract The synthetic compound N-cyanosulphonamide S0859 has been described as a selective inhibitor of sodium-bicarbonate coTransporters (NBC, SLC4 ) in mammalian heart ( Ch'en et al., 2008 ). First, for comparison, the electrogenic human NBCe1 ( SLC4A4 ) was heterologously expressed in Xenopus laevis oocytes, where its transport activity was inhibited by S0859 with an IC 50 of 9 µM. The activity of Monocarboxylate Transporter (MCT) isoforms 1, 2, and 4 ( SLC16A1, SLC16A7, SLC16A3 ), which transport lactate, pyruvate and ketone bodies, were also heterologously expressed in Xenopus oocytes, and their transport activity was similarly and reversibly inhibited by S0859 with an IC 50 of 4–10 µM. Partial inhibition of lactate transport by S0859 (50 µM) was also obtained in cultured astrocytes of mice. Thus, S0859 appears to be an inhibitor of anion transport with a broader spectrum than previously thought, and may also interfere with cellular metabolite uptake/release.

  • The loop between helix 4 and helix 5 in the Monocarboxylate Transporter MCT1 is important for substrate selection and protein stability.
    The Biochemical journal, 2003
    Co-Authors: Sandra Galić, Angelika Bröer, Joachim W. Deitmer, Hans-peter Schneider, Stefan Broer
    Abstract:

    Transport of lactate, pyruvate and the ketone bodies acetoacetate and beta-hydroxybutyrate, is mediated in most mammalian cells by members of the Monocarboxylate Transporter family (SLC16). A conserved signature sequence has been identified in this family, which is located in the loop between helix 4 and helix 5 and extends into helix 5. We have mutated residues in this signature sequence in the rat Monocarboxylate Transporter (MCT1) to elucidate the significance of this region for Monocarboxylate transport. Mutation of R143 and G153 resulted in complete inactivation of the Transporter. For the MCT1(G153V) mutant this was explained by a failure to reach the plasma membrane. The lack of transport activity of MCT1(R143Q) could be partially rescued by the conservative exchange R143H. The resulting mutant Transporter displayed reduced stability, a decreased V (max) of lactate transport but not of acetate transport, and an increased stereoselectivity. Mutation of K137, K141 and K142 indicated that only K142 played a significant role in the transport mechanism. Mutation of K142 to glutamine resulted in an increase of the K (m) for lactate from 5 mM to 12 mM. In contrast with MCT1(R143H), MCT1(K142Q) was less stereoselective than the wild-type. A mechanism is proposed that includes all critical residues.

  • Characterization of the high-affinity Monocarboxylate Transporter MCT2 in Xenopus laevis oocytes.
    Biochemical Journal, 1999
    Co-Authors: Stefan Broer, Angelika Bröer, Hans-peter Schneider, Carola Stegen, Andrew P. Halestrap, Joachim W. Deitmer
    Abstract:

    Observations on lactate transport in brain cells and cardiac myocytes indicate the presence of a high-affinity Monocarboxylate Transporter. The rat Monocarboxylate Transporter isoform MCT2 was analysed by expression in Xenopus laevis oocytes and the results were compared with the known characteristics of lactate transport in heart and brain. Monocarboxylate transport via MCT2 was driven by the H(+) gradient over the plasma membrane. Uptake of lactate strongly increased with decreasing pH, showing half-maximal stimulation at pH 7.2. A wide variety of Monocarboxylates and ketone bodies, including lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, 2-oxoisovalerate and 2-oxoisohexanoate, were substrates of MCT2. All substrates had a high affinity for MCT2. For lactate a K(m) value of 0.74+/-0.07 mM was determined at pH 7.0. For the other substrates, K(i) values between 100 microM and 1 mM were measured for inhibition of lactate transport, which is about one-tenth of the corresponding values for the ubiquitously expressed Monocarboxylate Transporter isoform MCT1. Monocarboxylate transport via MCT2 could be inhibited by alpha-cyano-4-hydroxycinnamate, anion-channel inhibitors and flavonoids. It is suggested that cells which express MCT2 preferentially use lactate and ketone bodies as energy sources.

Stefan Broer - One of the best experts on this subject based on the ideXlab platform.

  • The loop between helix 4 and helix 5 in the Monocarboxylate Transporter MCT1 is important for substrate selection and protein stability.
    The Biochemical journal, 2003
    Co-Authors: Sandra Galić, Angelika Bröer, Joachim W. Deitmer, Hans-peter Schneider, Stefan Broer
    Abstract:

    Transport of lactate, pyruvate and the ketone bodies acetoacetate and beta-hydroxybutyrate, is mediated in most mammalian cells by members of the Monocarboxylate Transporter family (SLC16). A conserved signature sequence has been identified in this family, which is located in the loop between helix 4 and helix 5 and extends into helix 5. We have mutated residues in this signature sequence in the rat Monocarboxylate Transporter (MCT1) to elucidate the significance of this region for Monocarboxylate transport. Mutation of R143 and G153 resulted in complete inactivation of the Transporter. For the MCT1(G153V) mutant this was explained by a failure to reach the plasma membrane. The lack of transport activity of MCT1(R143Q) could be partially rescued by the conservative exchange R143H. The resulting mutant Transporter displayed reduced stability, a decreased V (max) of lactate transport but not of acetate transport, and an increased stereoselectivity. Mutation of K137, K141 and K142 indicated that only K142 played a significant role in the transport mechanism. Mutation of K142 to glutamine resulted in an increase of the K (m) for lactate from 5 mM to 12 mM. In contrast with MCT1(R143H), MCT1(K142Q) was less stereoselective than the wild-type. A mechanism is proposed that includes all critical residues.

  • Characterization of the high-affinity Monocarboxylate Transporter MCT2 in Xenopus laevis oocytes.
    Biochemical Journal, 1999
    Co-Authors: Stefan Broer, Angelika Bröer, Hans-peter Schneider, Carola Stegen, Andrew P. Halestrap, Joachim W. Deitmer
    Abstract:

    Observations on lactate transport in brain cells and cardiac myocytes indicate the presence of a high-affinity Monocarboxylate Transporter. The rat Monocarboxylate Transporter isoform MCT2 was analysed by expression in Xenopus laevis oocytes and the results were compared with the known characteristics of lactate transport in heart and brain. Monocarboxylate transport via MCT2 was driven by the H(+) gradient over the plasma membrane. Uptake of lactate strongly increased with decreasing pH, showing half-maximal stimulation at pH 7.2. A wide variety of Monocarboxylates and ketone bodies, including lactate, pyruvate, beta-hydroxybutyrate, acetoacetate, 2-oxoisovalerate and 2-oxoisohexanoate, were substrates of MCT2. All substrates had a high affinity for MCT2. For lactate a K(m) value of 0.74+/-0.07 mM was determined at pH 7.0. For the other substrates, K(i) values between 100 microM and 1 mM were measured for inhibition of lactate transport, which is about one-tenth of the corresponding values for the ubiquitously expressed Monocarboxylate Transporter isoform MCT1. Monocarboxylate transport via MCT2 could be inhibited by alpha-cyano-4-hydroxycinnamate, anion-channel inhibitors and flavonoids. It is suggested that cells which express MCT2 preferentially use lactate and ketone bodies as energy sources.

  • comparison of lactate transport in astroglial cells and Monocarboxylate Transporter 1 mct 1 expressing xenopus laevis oocytes expression of two different Monocarboxylate Transporters in astroglial cells and neurons
    Journal of Biological Chemistry, 1997
    Co-Authors: Stefan Broer, Basim Rahman, Bernd Hamprecht, Luc Pellerin, Gioranni Pellegri, Jeanluc Martin, Stephan Verleysdonk, Pierre J Magistretti
    Abstract:

    Abstract The transport of lactate is an essential part of the concept of metabolic coupling between neurons and glia. Lactate transport in primary cultures of astroglial cells was shown to be mediated by a single saturable transport system with aK m value for lactate of 7.7 mm and aV max value of 250 nmol/(min × mg of protein). Transport was inhibited by a variety of Monocarboxylates and by compounds known to inhibit Monocarboxylate transport in other cell types, such as α-cyano-4-hydroxycinnamate andp-chloromercurbenzenesulfonate. Using reverse transcriptase-polymerase chain reaction and Northern blotting, the presence of mRNA coding for the Monocarboxylate Transporter 1 (MCT1) was demonstrated in primary cultures of astroglial cells. In contrast, neuron-rich primary cultures were found to contain the mRNA coding for the Monocarboxylate Transporter 2 (MCT2). MCT1 was cloned and expressed in Xenopus laevis oocytes. Comparison of lactate transport in MCT1 expressing oocytes with lactate transport in glial cells revealed that MCT1 can account for all characteristics of lactate transport in glial cells. These data provide further molecular support for the existence of a lactate shuttle between astrocytes and neurons.