1
|
Peluffo RD. Cationic amino acid transporters and their modulation by nitric oxide in cardiac muscle cells. Biophys Rev 2022; 13:1071-1079. [PMID: 35059028 DOI: 10.1007/s12551-021-00870-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/22/2021] [Indexed: 01/03/2023] Open
Abstract
Cationic amino acid transporters (CATs) play a central role in the supply of the substrate L-arginine to intracellular nitric oxide synthases (NOS), the enzymes responsible for the synthesis of nitric oxide (NO). In heart, NO produced by cardiac myocytes has diverse and even opposite effects on myocardial contractility depending on the subcellular location of its production. Approximately a decade ago, using a combination of biophysical and biochemical approaches, we discovered and characterized high- and low-affinity CATs that function simultaneously in the cardiac myocyte plasma membrane. Later on, we reported a negative feedback regulation of NO on the activity of cardiac CATs. In this way, NO was found to modulate its own biosynthesis by regulating the amount of L-arginine that becomes available as NOS substrate. We have recently solved the molecular determinants for this NO regulation on the low-affinity high-capacity CAT-2A. This review highlights some biophysical and biochemical features of L-arginine transporters and their potential relation to cardiac muscle physiology and pathology.
Collapse
Affiliation(s)
- R Daniel Peluffo
- Group of Biophysical Chemistry, Department of Biological Sciences, CENUR Litoral Norte, Universidad de La República, Rivera 1350, CP: 50000 Salto, Uruguay.,Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, New Jersey Medical School, Rutgers, The State University of New Jersey, 185 South Orange Avenue, Newark, NJ 07103 USA
| |
Collapse
|
2
|
Fairweather SJ, Rajendran E, Blume M, Javed K, Steinhöfel B, McConville MJ, Kirk K, Bröer S, van Dooren GG. Coordinated action of multiple transporters in the acquisition of essential cationic amino acids by the intracellular parasite Toxoplasma gondii. PLoS Pathog 2021; 17:e1009835. [PMID: 34432856 PMCID: PMC8423306 DOI: 10.1371/journal.ppat.1009835] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 09/07/2021] [Accepted: 07/23/2021] [Indexed: 02/07/2023] Open
Abstract
Intracellular parasites of the phylum Apicomplexa are dependent on the scavenging of essential amino acids from their hosts. We previously identified a large family of apicomplexan-specific plasma membrane-localized amino acid transporters, the ApiATs, and showed that the Toxoplasma gondii transporter TgApiAT1 functions in the selective uptake of arginine. TgApiAT1 is essential for parasite virulence, but dispensable for parasite growth in medium containing high concentrations of arginine, indicating the presence of at least one other arginine transporter. Here we identify TgApiAT6-1 as the second arginine transporter. Using a combination of parasite assays and heterologous characterisation of TgApiAT6-1 in Xenopus laevis oocytes, we demonstrate that TgApiAT6-1 is a general cationic amino acid transporter that mediates both the high-affinity uptake of lysine and the low-affinity uptake of arginine. TgApiAT6-1 is the primary lysine transporter in the disease-causing tachyzoite stage of T. gondii and is essential for parasite proliferation. We demonstrate that the uptake of cationic amino acids by TgApiAT6-1 is ‘trans-stimulated’ by cationic and neutral amino acids and is likely promoted by an inwardly negative membrane potential. These findings demonstrate that T. gondii has evolved overlapping transport mechanisms for the uptake of essential cationic amino acids, and we draw together our findings into a comprehensive model that highlights the finely-tuned, regulated processes that mediate cationic amino acid scavenging by these intracellular parasites. The causative agent of toxoplasmosis, Toxoplasma gondii, is a versatile intracellular parasite that can proliferate within nucleated cells of warm-blooded organisms. In order to survive, T. gondii parasites must scavenge the cationic amino acids lysine and arginine from their hosts. In a previous study, we demonstrated that a plasma membrane-localized protein called TgApiAT1 facilitates the uptake of arginine into the parasite. We found that parasites lacking TgApiAT1 could proliferate when cultured in medium containing high concentrations of arginine, suggesting the existence of an additional uptake pathway for arginine. In the present study, we demonstrate that this second uptake pathway is mediated by TgApiAT6-1, a protein belonging to the same solute transporter family as TgApiAT1. We show that TgApiAT6-1 is the major lysine transporter of the parasite, and that it is critical for parasite proliferation. Furthermore, we demonstrate that TgApiAT6-1 can transport arginine into parasites under conditions in which arginine concentrations are high and lysine concentrations are comparatively lower. These data support a model for the finely-tuned acquisition of essential cationic amino acids that involves multiple transporters, and which likely contributes to these parasites being able to survive and proliferate within a wide variety of host cell types.
Collapse
Affiliation(s)
- Stephen J. Fairweather
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
- * E-mail: (SJF); (GGvD)
| | - Esther Rajendran
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Martin Blume
- Department of Biochemistry and Molecular Biology and the Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
- Robert Koch Institute, Berlin, Germany
| | - Kiran Javed
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Birte Steinhöfel
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
- Humboldt University Berlin, Berlin, Germany
| | - Malcolm J. McConville
- Department of Biochemistry and Molecular Biology and the Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Stefan Bröer
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Giel G. van Dooren
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
- * E-mail: (SJF); (GGvD)
| |
Collapse
|
3
|
Rajendran E, Hapuarachchi SV, Miller CM, Fairweather SJ, Cai Y, Smith NC, Cockburn IA, Bröer S, Kirk K, van Dooren GG. Cationic amino acid transporters play key roles in the survival and transmission of apicomplexan parasites. Nat Commun 2017; 8:14455. [PMID: 28205520 PMCID: PMC5316894 DOI: 10.1038/ncomms14455] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 12/30/2016] [Indexed: 11/09/2022] Open
Abstract
Apicomplexans are obligate intracellular parasites that scavenge essential nutrients from their hosts via transporter proteins on their plasma membrane. The identities of the transporters that mediate amino acid uptake into apicomplexans are unknown. Here we demonstrate that members of an apicomplexan-specific protein family-the Novel Putative Transporters (NPTs)-play key roles in the uptake of cationic amino acids. We show that an NPT from Toxoplasma gondii (TgNPT1) is a selective arginine transporter that is essential for parasite survival and virulence. We also demonstrate that a homologue of TgNPT1 from the malaria parasite Plasmodium berghei (PbNPT1), shown previously to be essential for the sexual gametocyte stage of the parasite, is a cationic amino acid transporter. This reveals a role for cationic amino acid scavenging in gametocyte biology. Our study demonstrates a critical role for amino acid transporters in the survival, virulence and life cycle progression of these parasites.
Collapse
Affiliation(s)
- Esther Rajendran
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Sanduni V Hapuarachchi
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Catherine M Miller
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Smithfield, Queensland 4878, Australia
| | - Stephen J Fairweather
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Yeping Cai
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Nicholas C Smith
- Queensland Tropical Health Alliance Research Laboratory, Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, Queensland 4878, Australia
| | - Ian A Cockburn
- John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Stefan Bröer
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Giel G van Dooren
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
| |
Collapse
|
4
|
Cremades A, Del Rio-Garcia J, Lambertos A, López-Garcia C, Peñafiel R. Tissue-specific regulation of potassium homeostasis by high doses of cationic amino acids. SPRINGERPLUS 2016; 5:616. [PMID: 27330882 PMCID: PMC4870509 DOI: 10.1186/s40064-016-2224-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 04/22/2016] [Indexed: 01/19/2023]
Abstract
The administration of l-arginine hydrochloride has been used for testing pituitary secretion in humans, and as an experimental model for induction of acute pancreatitis in rats and mice. Whereas in the first case, the administration of the amino acid is associated with hiperkalemia, in the model of acute pancreatitis no data are available on possible changes in potassium homeostasis. The present study shows that the acute administration to mice of l-arginine hydrochloride or other cationic amino acids almost duplicate plasma potassium levels. This effect was associated to a marked decrease of tissue potassium in both pancreas and liver. No changes were found in other tissues. These changes cannot be ascribed to the large load of chloride ions, since similar effects were produced when l-ornithine aspartate was administered. The changes in potassium levels were dependent on the dose. The displacement of intracellular potassium from the liver and pancreas to the extracellular compartment appears to be dependent on the entry of the cationic amino acid, since the administration of an equivalent dose of alfa-difluoromethyl ornithine HCl (DFMO), a non physiological analog of l-ornithine, which is poorly taken by the tissues in comparison with the physiological cationic amino acids, did not produce any change in potassium levels in pancreas and liver. The analyses of the expression of cationic amino acid transporters (CAT) suggest that the CAT-2 transporter may be implicated in the potassium/cationic amino acid interchange in liver and pancreas. The possible physiological or pathological relevance of these findings is discussed.
Collapse
Affiliation(s)
- Asunción Cremades
- Department of Pharmacology, Faculty of Medicine, University of Murcia, Murcia, Spain ; Biomedical Research Institute of Murcia (IMIB), Murcia, Spain
| | - Jesús Del Rio-Garcia
- Department of Pharmacology, Faculty of Medicine, University of Murcia, Murcia, Spain
| | - Ana Lambertos
- Department of Biochemistry, Molecular Biology B and Immunology, School of Medicine, University of Murcia, 30100 Murcia, Spain
| | - Carlos López-Garcia
- Department of Pharmacology, Faculty of Medicine, University of Murcia, Murcia, Spain
| | - Rafael Peñafiel
- Department of Biochemistry, Molecular Biology B and Immunology, School of Medicine, University of Murcia, 30100 Murcia, Spain ; Biomedical Research Institute of Murcia (IMIB), Murcia, Spain
| |
Collapse
|
5
|
Linking our understanding of mammary gland metabolism to amino acid nutrition. Amino Acids 2014; 46:2447-62. [DOI: 10.1007/s00726-014-1818-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 07/25/2014] [Indexed: 12/15/2022]
|
6
|
Steppan J, Nyhan D, Berkowitz DE. Development of novel arginase inhibitors for therapy of endothelial dysfunction. Front Immunol 2013; 4:278. [PMID: 24062745 PMCID: PMC3774993 DOI: 10.3389/fimmu.2013.00278] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 08/29/2013] [Indexed: 01/18/2023] Open
Abstract
Endothelial dysfunction and resulting vascular pathology have been identified as an early hallmark of multiple diseases, including diabetes mellitus. One of the major contributors to endothelial dysfunction is a decrease in nitric oxide (NO) bioavailability, impaired NO signaling, and an increase in the amount of reactive oxygen species (ROS). In the endothelium NO is produced by endothelial nitric oxide synthase (eNOS), for which l-arginine is a substrate. Arginase, an enzyme critical in the urea cycle also metabolizes l-arginine, thereby directly competing with eNOS for their common substrate and constraining its bioavailability for eNOS, thereby compromising NO production. Arginase expression and activity is upregulated in many cardiovascular diseases including ischemia reperfusion injury, hypertension, atherosclerosis, and diabetes mellitus. More importantly, since the 1990s, specific arginase inhibitors such as N-hydroxy-guanidinium or N-hydroxy-nor-l-arginine, and boronic acid derivatives, such as, 2(S)-amino-6-boronohexanoic acid, and S-(2-boronoethyl)-l-cysteine, that can bridge the binuclear manganese cluster of arginase have been developed. These highly potent and specific inhibitors can now be used to probe arginase function and thereby modulate the redox milieu of the cell by changing the balance between NO and ROS. Inspired by this success, drug discovery programs have recently led to the identification of α–α-disubstituted amino acid based arginase inhibitors [such as (R)-2-amino-6-borono-2-(2-(piperidin-1-yl)ethyl)hexanoic acid], that are currently under early investigation as therapeutics. Finally, some investigators concentrate on identification of plant derived compounds with arginase inhibitory capability, such as piceatannol-3′-O-β-d-glucopyranoside (PG). All of these synthesized or naturally derived small molecules may represent novel therapeutics for vascular disease particularly that associated with diabetes.
Collapse
Affiliation(s)
- Jochen Steppan
- Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins Medical Institutions , Baltimore, MD , USA
| | | | | |
Collapse
|
7
|
Simon A, Karbach S, Habermeier A, Closs EI. Decoding the substrate supply to human neuronal nitric oxide synthase. PLoS One 2013; 8:e67707. [PMID: 23874440 PMCID: PMC3706577 DOI: 10.1371/journal.pone.0067707] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 05/21/2013] [Indexed: 12/21/2022] Open
Abstract
Nitric oxide, produced by the neuronal nitric oxide synthase (nNOS) from L-arginine is an important second messenger molecule in the central nervous system: It influences the synthesis and release of neurotransmitters and plays an important role in long-term potentiation, long-term depression and neuroendocrine secretion. However, under certain pathological conditions such as Alzheimer’s or Parkinson’s disease, stroke and multiple sclerosis, excessive NO production can lead to tissue damage. It is thus desirable to control NO production in these situations. So far, little is known about the substrate supply to human nNOS as a determinant of its activity. Measuring bioactive NO via cGMP formation in reporter cells, we demonstrate here that nNOS in both, human A673 neuroepithelioma and TGW-nu-I neuroblastoma cells can be fast and efficiently nourished by extracellular arginine that enters the cells via membrane transporters (pool I that is freely exchangeable with the extracellular space). When this pool was depleted, NO synthesis was partially sustained by intracellular arginine sources not freely exchangeable with the extracellular space (pool II). Protein breakdown made up by far the largest part of pool II in both cell types. In contrast, citrulline to arginine conversion maintained NO synthesis only in TGW-nu-I neuroblastoma, but not A673 neuroepithelioma cells. Histidine mimicked the effect of protease inhibitors causing an almost complete nNOS inhibition in cells incubated additionally in lysine that depletes the exchangeable arginine pool. Our results identify new ways to modulate nNOS activity by modifying its substrate supply.
Collapse
Affiliation(s)
- Alexandra Simon
- Department of Pharmacology, University Medical Centre of the Johannes Gutenberg University, Mainz, Germany
| | - Susanne Karbach
- Department of Pharmacology, University Medical Centre of the Johannes Gutenberg University, Mainz, Germany
| | - Alice Habermeier
- Department of Pharmacology, University Medical Centre of the Johannes Gutenberg University, Mainz, Germany
| | - Ellen I. Closs
- Department of Pharmacology, University Medical Centre of the Johannes Gutenberg University, Mainz, Germany
- * E-mail:
| |
Collapse
|
8
|
Ryoo S, Berkowitz DE, Lim HK. Endothelial arginase II and atherosclerosis. Korean J Anesthesiol 2011; 61:3-11. [PMID: 21860744 PMCID: PMC3155133 DOI: 10.4097/kjae.2011.61.1.3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 07/04/2011] [Accepted: 07/04/2011] [Indexed: 01/11/2023] Open
Abstract
Atherosclerotic vascular disease is the leading cause of morbidity and mortality in developed countries. While it is a complex condition resulting from numerous genetic and environmental factors, it is well recognized that oxidized low-density lipoprotein produces pro-atherogenic effects in endothelial cells (ECs) by inducing the expression of adhesion molecules, stimulating EC apoptosis, inducing superoxide anion formation and impairing protective endothelial nitric oxide (NO) formation. Emerging evidence suggests that the enzyme arginase reciprocally regulates NO synthase and NO production by competing for the common substrate L-arginine. As oxidized LDL (OxLDL) results in arginase activation/upregulation, it appears to be an important contributor to endothelial dysfunction by a mechanism that involves substrate limitation for endothelial NO synthase (eNOS) and NO synthesis. Additionally, arginase enhances production of reactive oxygen species by eNOS. Arginase inhibition in hypercholesterolemic (ApoE-/-) mice or arginase II deletion (ArgII-/-) mice restores endothelial vasorelaxant function, reduces vascular stiffness and markedly reduces atherosclerotic plaque burden. Furthermore, arginase activation contributes to vascular changes including polyamine-dependent vascular smooth muscle cell proliferation and collagen synthesis. Collectively, arginase may play a key role in the prevention and treatment of atherosclerotic vascular disease.
Collapse
Affiliation(s)
- Sungwoo Ryoo
- Division of Biology, Kangwon National University, Chuncheon, Korea
| | | | | |
Collapse
|
9
|
Ryoo S, Berkowitz DE, Lim HK. Endothelial arginase II and atherosclerosis. Korean J Anesthesiol 2011. [DOI: 10.4097/kjae.2011.60.6.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Sungwoo Ryoo
- Division of Biology, Kangwon National University, Chuncheon, Korea
| | - Dan E. Berkowitz
- Department of Anesthesiology and Critical Medicine and Biomedical Engineering, The Johns Hopkins Medical Institutes, Baltimore, MD, USA
| | - Hyun Kyo Lim
- Department of Anesthesiology and Pain Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| |
Collapse
|
10
|
Affiliation(s)
- Carmelle V Remillard
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093-0725, USA
| | | |
Collapse
|
11
|
Abstract
L-Arginine (L-Arg) is a basic amino acid that plays a central role in the biosynthesis of nitric oxide, creatine, agmantine, polyamines, proline and glutamate. Most tissues, including myocardium, must import L-Arg from the circulation to ensure adequate intracellular levels of this amino acid. This study reports novel L-Arg-activated inward currents in whole-cell voltage-clamped rat ventricular cardiomyocytes. Ion-substitution experiments identified extracellular L-Arg as the charge-carrying cationic species responsible for these currents, which, thus, represent L-Arg import into cardiac myocytes. This result was independently confirmed by an increase in myocyte nitric oxide production upon extracellular application of L-Arg. The inward movement of Arg molecules was found to be passive and independent of Na(2+), K(2+), Ca(2+) and Mg(2+). The process displayed saturation and membrane potential (V(m))-dependent kinetics, with a K(0.5) for l-Arg that increased from 5 mm at hyperpolarizing V(m) to 20 mm at +40 mV. L-Lysine and L-ornithine but not D-Arg produced currents with characteristics similar to that activated by L-Arg indicating that the transport process is stereospecific for cationic L-amino acids. L-Arg current was fully blocked after brief incubation with 0.2 mm N-ethylmaleimide. These features suggest that the activity of the low-affinity, high-capacity CAT-2A member of the y(2+) family of transporters is responsible for L-Arg currents in acutely isolated cardiomyocytes. Regardless of the mechanism, we hypothesize that a low-affinity arginine transport process in heart, by ensuring substrate availability for sustained NO production, might play a cardio-protective role during catabolic states known to increase Arg plasma levels severalfold.
Collapse
Affiliation(s)
- R Daniel Peluffo
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, PO Box 1709, Newark, NJ 07101-1709, USA.
| |
Collapse
|
12
|
Gilles W, Vulcu SD, Liewald JF, Habermeier A, Vékony N, Closs EI, Rupp J, Nawrath H. Monovalent cation conductance in Xenopus laevis oocytes expressing hCAT-3. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1668:234-9. [PMID: 15737334 DOI: 10.1016/j.bbamem.2004.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2004] [Revised: 12/17/2004] [Accepted: 12/20/2004] [Indexed: 11/18/2022]
Abstract
hCAT-3 (human cationic amino acid transporter type three) was investigated with both the two-electrode voltage clamp method and tracer experiments. Oocytes expressing hCAT-3 displayed less negative membrane potentials and larger voltage-dependent currents than native or water-injected oocytes did. Ion substitution experiments in hCAT-3-expressing oocytes revealed a large conductance for Na+ and K+. In the presence of L-Arg, voltage-dependent inward and outward currents were observed. At symmetrical (inside/outside) concentrations of L-Arg, the conductance of the transporter increased monoexponentially with the L-Arg concentrations; the calculated Vmax and KM values amounted to 8.3 microS and 0.36 mM, respectively. The time constants of influx and efflux of [3H]L-Arg, at symmetrically inside/outside L-Arg concentrations (1 mM), amounted to 79 and 77 min, respectively. The flux data and electrophysiological experiments suggest that the transport of L-Arg through hCAT-3 is symmetric, when the steady state of L-Arg flux has been reached. It is concluded that hCAT-3 is a passive transport system that conducts monovalent cations including L-Arg. The particular role of hCAT-3 in the diverse tissues remains to be elucidated.
Collapse
Affiliation(s)
- Wolfgang Gilles
- Department of Pharmacology, Johannes-Gutenberg University, Obere Zahlbacher Str. 67, 55101 Mainz, Germany
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Hatzoglou M, Fernandez J, Yaman I, Closs E. Regulation of cationic amino acid transport: the story of the CAT-1 transporter. Annu Rev Nutr 2004; 24:377-99. [PMID: 15459982 DOI: 10.1146/annurev.nutr.23.011702.073120] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The discovery of the function of the receptor for the ecotropic retrovirus as a membrane transporter for the essential amino acids lysine and arginine was a landmark finding in the field of molecular nutrition. This finding indicated that cationic amino acid transporters (CATs) act pathologically as viral receptors. The importance of this transporter was further supported by knockout mice that were not viable after birth. CAT-1 was the first amino acid transporter to be cloned; several other CATs were later characterized biochemically and molecularly. These transporters mediate the bidirectional transport of cationic amino acids, thus supporting important metabolic functions, such as synthesis of proteins, nitric oxide (NO) synthesis, polyamine biosynthesis, and interorgan amino acid flow. This review briefly describes the advances in the regulation of cationic amino acid transport, focusing on the molecular mechanisms that regulate the CAT-1 transporter. Of particular interest to this review is the regulation of CAT-1 by nutritional stresses, such as amino acid availability. The studies that are reviewed conclude that the CAT-1 gene is essential for cell survival during stress because it allows cells to resume growth as soon as amino acids become available.
Collapse
Affiliation(s)
- Maria Hatzoglou
- Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
| | | | | | | |
Collapse
|
14
|
Closs EI, Simon A, Vékony N, Rotmann A. Plasma membrane transporters for arginine. J Nutr 2004; 134:2752S-2759S; discussion 2765S-2767S. [PMID: 15465780 DOI: 10.1093/jn/134.10.2752s] [Citation(s) in RCA: 187] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The supply of arginine may become rate limiting for enzymatic reactions that use this semiessential amino acid as a substrate (e.g., nitric oxide, agmatine, creatine, and urea synthesis), particularly under conditions of high demand such as growth, sepsis, or wound healing. In addition, arginine acts as a signaling molecule that regulates essential cellular functions such as protein synthesis, apoptosis, and growth. In the past decade, a number of carrier proteins for amino acids have been identified on the molecular level. They belong to different gene families, exhibit overlapping but distinctive substrate specificities, and can further be distinguished by their requirement for the cotransport or countertransport of inorganic ions. A number of these transporters function as exchangers rather than uniporters. Uptake of amino acids by these transporters therefore depends largely on the intracellular substrate composition. Hence, there is a complex crosstalk between transporters for cationic and neutral amino acids as well as for peptides. This article briefly reviews current knowledge regarding mammalian plasma membrane transporters that accept arginine as a substrate.
Collapse
Affiliation(s)
- Ellen I Closs
- Department of Pharmacology, Johannes Gutenberg University, 55101 Mainz, Germany.
| | | | | | | |
Collapse
|
15
|
Vulcu SD, Liewald JF, Gillen C, Rupp J, Nawrath H. Proton conductance of human transient receptor potential-vanilloid type-1 expressed in oocytes of Xenopus laevis and in Chinese hamster ovary cells. Neuroscience 2004; 125:861-6. [PMID: 15120847 DOI: 10.1016/j.neuroscience.2004.02.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2004] [Indexed: 11/20/2022]
Abstract
Transient receptor potential-vanilloid type-1 (TRPV1) is a ligand-gated cation channel with preference for divalent cations, especially Ca(2+) (sequence of conductances: Ca(2+)>Mg(2+)>Na(+) approximately/= K(+) approximately/= Cs(+)). In the present study, the two-electrode voltage-clamp technique was used on oocytes of Xenopus laevis expressing TRPV1 to evaluate whether human TRPV1 also conducts protons. In medium devoid of K(+), Na(+), Mg(2+), and Ca(2+), capsaicin 1 microM induced a significant inward current (62% of the current in physiological medium). The effects of capsaicin were abolished in the presence of capsazepine 3 microM. The capsaicin-induced currents in medium devoid of Na(+), K(+), Mg(2+), and Ca(2+) were dependent on pH, causing larger inward currents and less negative reversal potentials at low pH and vice versa. The same current was also demonstrated in Chinese hamster ovary cells expressing human TRPV1. We conclude that TRPV1 conducts protons, in addition to Na(+), K(+), Mg(2+), and Ca(2+). The proton conductance may help to initiate action potentials and to translocate H(+) dependent on TRPV1 activation and membrane potential.
Collapse
Affiliation(s)
- S D Vulcu
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacherstrasse 67, D-55101 Mainz, Germany
| | | | | | | | | |
Collapse
|
16
|
Faulhammer D, Eschgfäller B, Stark S, Burgstaller P, Englberger W, Erfurth J, Kleinjung F, Rupp J, Dan Vulcu S, Schröder W, Vonhoff S, Nawrath H, Gillen C, Klussmann S. Biostable aptamers with antagonistic properties to the neuropeptide nociceptin/orphanin FQ. RNA (NEW YORK, N.Y.) 2004; 10:516-27. [PMID: 14970396 PMCID: PMC1370946 DOI: 10.1261/rna.5186504] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2003] [Accepted: 11/07/2003] [Indexed: 05/24/2023]
Abstract
The neuropeptide nociceptin/orphanin FQ (N/OFQ), the endogenous ligand of the opioid receptor-like 1 (ORL1) receptor, has been shown to play a prominent role in the regulation of several biological functions such as pain and stress. Here we describe the isolation and characterization of N/OFQ binding biostable RNA aptamers (Spiegelmers) using a mirror-image in vitro selection approach. Spiegelmers are L-enantiomeric oligonucleotide ligands that display high affinity and specificity to their targets and high resistance to enzymatic degradation compared to D-oligonucleotides. A representative Spiegelmer from the selections performed was size-minimized to two distinct sequences capable of high affinity binding to N/OFQ. The Spiegelmers were shown to antagonize binding of N/OFQ to the ORL1 receptor in a binding-competition assay. The calculated IC(50) values for the Spiegelmers NOX 2149 and NOX 2137a/b were 110 nM and 330 nM, respectively. The competitive antagonistic properties of these Spiegelmers were further demonstrated by their effective and specific inhibition of G-protein activation in two additional models. The Spiegelmers antagonized the N/OFQ-induced GTPgammaS incorporation into cell membranes of a CHO-K1 cell line expressing the human ORL1 receptor. In oocytes from Xenopus laevis, NOX 2149 showed an antagonistic effect to the N/OFQ-ORL 1 receptor system that was functionally coupled with G-protein-regulated inwardly rectifying K(+) channels.
Collapse
|
17
|
Rotmann A, Closs EI, Liewald JF, Nawrath H. Intracellular accumulation of l-Arg, kinetics of transport, and potassium leak conductance in oocytes from Xenopus laevis expressing hCAT-1, hCAT-2A, and hCAT-2B. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1660:138-43. [PMID: 14757229 DOI: 10.1016/j.bbamem.2003.11.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cationic amino acid transporters play an important role in the intracellular supply of L-Arg and the generation of nitric oxide. Since the transport of L-Arg is voltage-dependent, we aimed at determining the intracellular L-Arg concentration and describing the transport of L-Arg in terms of Michaelis-Menten kinetics, taking into account membrane voltage. The human isoforms of the cationic amino acid transporters, hCAT-1, hCAT-2A, and hCAT-2B, were expressed in oocytes from Xenopus laevis and studied with the voltage clamp technique and in tracer experiments. We found that L-Arg was concentrated intracellularly by all hCAT isoforms and that influx and efflux, in the steady state of exchange, were nearly mirror images. Conductance measurements at symmetric concentrations of L-Arg (inside/outside) allowed us to determine KM and Vmax. The empty transporter of hCAT-2B featured an unexpected potassium conductance, which was inhibited by L-Arg.
Collapse
Affiliation(s)
- Alexander Rotmann
- Department of Pharmacology, University of Mainz, Obere Zahlbacherstr 67, D-55101 Mainz, Germany
| | | | | | | |
Collapse
|
18
|
Mann GE, Yudilevich DL, Sobrevia L. Regulation of amino acid and glucose transporters in endothelial and smooth muscle cells. Physiol Rev 2003; 83:183-252. [PMID: 12506130 DOI: 10.1152/physrev.00022.2002] [Citation(s) in RCA: 319] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
While transport processes for amino acids and glucose have long been known to be expressed in the luminal and abluminal membranes of the endothelium comprising the blood-brain and blood-retinal barriers, it is only within the last decades that endothelial and smooth muscle cells derived from peripheral vascular beds have been recognized to rapidly transport and metabolize these nutrients. This review focuses principally on the mechanisms regulating amino acid and glucose transporters in vascular endothelial cells, although we also summarize recent advances in the understanding of the mechanisms controlling membrane transport activity and expression in vascular smooth muscle cells. We compare the specificity, ionic dependence, and kinetic properties of amino acid and glucose transport systems identified in endothelial cells derived from cerebral, retinal, and peripheral vascular beds and review the regulation of transport by vasoactive agonists, nitric oxide (NO), substrate deprivation, hypoxia, hyperglycemia, diabetes, insulin, steroid hormones, and development. In view of the importance of NO as a modulator of vascular tone under basal conditions and in disease and chronic inflammation, we critically review the evidence that transport of L-arginine and glucose in endothelial and smooth muscle cells is modulated by bacterial endotoxin, proinflammatory cytokines, and atherogenic lipids. The recent colocalization of the cationic amino acid transporter CAT-1 (system y(+)), nitric oxide synthase (eNOS), and caveolin-1 in endothelial plasmalemmal caveolae provides a novel mechanism for the regulation of NO production by L-arginine delivery and circulating hormones such insulin and 17beta-estradiol.
Collapse
Affiliation(s)
- Giovanni E Mann
- Centre for Cardiovascular Biology and Medicine, Guy's, King's, and St. Thomas' School of Biomedical Sciences, King's College London, London, United Kingdom.
| | | | | |
Collapse
|
19
|
Diewald L, Rupp J, Dreger M, Hucho F, Gillen C, Nawrath H. Activation by acidic pH of CLC-7 expressed in oocytes from Xenopus laevis. Biochem Biophys Res Commun 2002; 291:421-4. [PMID: 11846422 DOI: 10.1006/bbrc.2002.6462] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
ClC chloride channels are important in diverse physiological functions such as transepithelial transport, cell volume regulation, excitability, and acidification of intracellular organelles. We have investigated the expression of CLC-7 in oocytes from Xenopus laevis with the two electrode voltage clamp technique and Western blot analysis. Using a specific antibody against CLC-7, we found an approximately 80 kDa protein in oocytes, previously injected with CLC-7-cRNA. In voltage clamp experiments on ClC-7-cRNA-injected oocytes, no current changes were detected at normal pH (7.4). However, acidification of the Ringer solution to pH values between 6 and 4 revealed strong currents which reversed at about -15 mV (30 mV positive to the normal resting potential) and showed strong outward rectification. We therefore suggest that ClC-7 in oocytes is a functional chloride current at acidic pH. Since ClC-7 is also found in neuronal tissues and was upregulated in a rat pain model, we suggest a role of CLC-7 also for nociception and pain.
Collapse
Affiliation(s)
- Linda Diewald
- Pharmakologisches Institute der Universität Mainz, Mainz, Germany
| | | | | | | | | | | |
Collapse
|
20
|
Closs EI. Expression, regulation and function of carrier proteins for cationic amino acids. Curr Opin Nephrol Hypertens 2002; 11:99-107. [PMID: 11753094 DOI: 10.1097/00041552-200201000-00015] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Different carrier proteins exhibiting distinct transport properties participate in cationic amino acid transport. There are sodium-independent systems, such as b+, y+, y+L and b0,+, and a sodium-dependent system B0,+, most of which have now been identified at the molecular level. In most non-epithelial cells, members of the cationic amino acid transporter (CAT) family mediating system y+ activity seem to be the major entry pathway for cationic amino acids. CAT proteins underlie complex regulation at the transcriptional, post-transcriptional and activity levels. Recent evidence indicates that individual CAT isoforms are necessary for providing the substrate for nitric oxide synthesis, for example CAT-1 for Ca2+-independent nitric oxide production in endothelial cells and CAT-2B for sustained nitric oxide production in macrophages.
Collapse
Affiliation(s)
- Ellen I Closs
- Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany.
| |
Collapse
|
21
|
Hammermann R, Stichnote C, Closs EI, Nawrath H, Racké K. Inhibition of nitric oxide synthase abrogates lipopolysaccharides-induced up-regulation of L-arginine uptake in rat alveolar macrophages. Br J Pharmacol 2001; 133:379-86. [PMID: 11375254 PMCID: PMC1572798 DOI: 10.1038/sj.bjp.0704091] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
It was tested whether the inducible nitric oxide synthase (iNOS) pathway might be involved in lipopolysaccharides-(LPS)-induced up-regulation of L-arginine transport in rat alveolar macrophages (AM). AM were cultured in absence or presence of LPS. Nitrite accumulation was determined in culture media and cells were used to study [3H]-L-arginine uptake or to isolate RNA for RT - PCR. Culture in presence of LPS (1 microg ml(-1), 20 h) caused 11 fold increase of nitrite accumulation and 2.5 fold increase of [3H]-L-arginine uptake. The inducible NO synthase (iNOS) inhibitor 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) present alone during culture had only marginal effects on [3H]-L-arginine uptake. However, AMT present during culture additionally to LPS, suppressed LPS-induced nitrite accumulation and LPS-stimulated [3H]-L-arginine uptake in the same concentration-dependent manner. AMT present only for the last 30 min of the culture period had similar effects on [3H]-L-arginine uptake. AMT present only during the uptake period also inhibited LPS-stimulated [3H]-L-arginine uptake, but with lower potency. The inhibitory effect of AMT could not be opposed by the NO releasing compound DETA NONOate. LPS caused an up-regulation of the mRNA for the cationic amino acid transporter CAT-2B, and this effect was not affected by AMT. AMT (100 microM) did not affect L-arginine transport studied by electrophysiological techniques in Xenopus laevis oocytes expressing either the human cationic amino acid transporter hCAT-1 or hCAT-2B. In conclusion, iNOS inhibition in rat AM abolished LPS-activated L-arginine uptake. This effect appears to be caused by reduced flow of L-arginine through the iNOS pathway.
Collapse
Affiliation(s)
- Rainer Hammermann
- Institute of Pharmacology and Toxicology, University of Bonn, Reuterstr. 2b, D-53113 Bonn, Germany
| | - Christina Stichnote
- Institute of Pharmacology and Toxicology, University of Bonn, Reuterstr. 2b, D-53113 Bonn, Germany
| | - Ellen Ildicho Closs
- Institute of Pharmacology, University of Mainz, Obere Zahlbacher Str. 67, D-55101 Mainz, Germany
| | - Hermann Nawrath
- Institute of Pharmacology, University of Mainz, Obere Zahlbacher Str. 67, D-55101 Mainz, Germany
| | - Kurt Racké
- Institute of Pharmacology and Toxicology, University of Bonn, Reuterstr. 2b, D-53113 Bonn, Germany
- Author for correspondence:
| |
Collapse
|