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Taurino G, Dander E, Chiu M, Pozzi G, Maccari C, Starace R, Silvestri D, Griffini E, Bianchi MG, Carubbi C, Andreoli R, Mirandola P, Valsecchi MG, Rizzari C, D'Amico G, Bussolati O. Asparagine transport through SLC1A5/ASCT2 and SLC38A5/SNAT5 is essential for BCP-ALL cell survival and a potential therapeutic target. Br J Haematol 2024. [PMID: 38736325 DOI: 10.1111/bjh.19516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 04/25/2024] [Indexed: 05/14/2024]
Abstract
B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) blasts strictly depend on the transport of extra-cellular asparagine (Asn), yielding a rationale for L-asparaginase (ASNase) therapy. However, the carriers used by ALL blasts for Asn transport have not been identified yet. Exploiting RS4;11 cells as BCP-ALL model, we have found that cell Asn is lowered by either silencing or inhibition of the transporters ASCT2 or SNAT5. The inhibitors V-9302 (for ASCT2) and GluγHA (for SNAT5) markedly lower cell proliferation and, when used together, suppress mTOR activity, induce autophagy and cause a severe nutritional stress, leading to a proliferative arrest and a massive cell death in both the ASNase-sensitive RS4;11 cells and the relatively ASNase-insensitive NALM-6 cells. The cytotoxic effect is not prevented by coculturing leukaemic cells with primary mesenchymal stromal cells. Leukaemic blasts of paediatric ALL patients express ASCT2 and SNAT5 at diagnosis and undergo marked cytotoxicity when exposed to the inhibitors. ASCT2 expression is positively correlated with the minimal residual disease at the end of the induction therapy. In conclusion, ASCT2 and SNAT5 are the carriers exploited by ALL cells to transport Asn, and ASCT2 expression is associated with a lower therapeutic response. ASCT2 may thus represent a novel therapeutic target in BCP-ALL.
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Affiliation(s)
- Giuseppe Taurino
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Erica Dander
- Tettamanti Center, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
| | - Martina Chiu
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Giulia Pozzi
- Laboratory of Human Anatomy, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Chiara Maccari
- Laboratory of Industrial Toxicology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Rita Starace
- Tettamanti Center, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
| | - Daniela Silvestri
- Tettamanti Center, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
| | - Erika Griffini
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Massimiliano G Bianchi
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
- MRH-Microbiome Research Hub, Parco Area Delle Scienze 11/A, University of Parma, Parma, Italy
| | - Cecilia Carubbi
- Laboratory of Human Anatomy, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Roberta Andreoli
- Laboratory of Industrial Toxicology, Department of Medicine and Surgery, University of Parma, Parma, Italy
- CERT-Center of Excellence for Toxicological Research, University of Parma, Parma, Italy
| | - Prisco Mirandola
- Laboratory of Human Anatomy, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Maria Grazia Valsecchi
- Biostatistics and Clinical Epidemiology, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
- School of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
| | - Carmelo Rizzari
- Department of Pediatrics, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
| | - Giovanna D'Amico
- Tettamanti Center, Fondazione IRCCS San Gerardo Dei Tintori, Monza, Italy
| | - Ovidio Bussolati
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
- MRH-Microbiome Research Hub, Parco Area Delle Scienze 11/A, University of Parma, Parma, Italy
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2
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Zhang D, Hua Z, Li Z. The role of glutamate and glutamine metabolism and related transporters in nerve cells. CNS Neurosci Ther 2024; 30:e14617. [PMID: 38358002 PMCID: PMC10867874 DOI: 10.1111/cns.14617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 12/15/2023] [Accepted: 01/10/2024] [Indexed: 02/16/2024] Open
Abstract
BACKGROUND Glutamate and glutamine are the most abundant amino acids in the blood and play a crucial role in cell survival in the nervous system. Various transporters found in cell and mitochondrial membranes, such as the solute carriers (SLCs) superfamily, are responsible for maintaining the balance of glutamate and glutamine in the synaptic cleft and within cells. This balance affects the metabolism of glutamate and glutamine as non-essential amino acids. AIMS This review aims to provide an overview of the transporters and enzymes associated with glutamate and glutamine in neuronal cells. DISCUSSION We delve into the function of glutamate and glutamine in the nervous system by discussing the transporters involved in the glutamate-glutamine cycle and the key enzymes responsible for their mutual conversion. Additionally, we highlight the role of glutamate and glutamine as carbon and nitrogen donors, as well as their significance as precursors for the synthesis of reduced glutathione (GSH). CONCLUSION Glutamate and glutamine play a crucial role in the brain due to their special effects. It is essential to focus on understanding glutamate and glutamine metabolism to comprehend the physiological behavior of nerve cells and to treat nervous system disorders and cancer.
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Affiliation(s)
- Dongyang Zhang
- Department of PediatricsShengjing Hospital of China Medical UniversityShenyangLiaoningChina
- Medical Research Center, Liaoning Key Laboratory of Research and Application of Animal Models for Environment and Metabolic DiseasesShengjing Hospital of China Medical UniversityShenyangLiaoningChina
| | - Zhongyan Hua
- Department of PediatricsShengjing Hospital of China Medical UniversityShenyangLiaoningChina
- Medical Research Center, Liaoning Key Laboratory of Research and Application of Animal Models for Environment and Metabolic DiseasesShengjing Hospital of China Medical UniversityShenyangLiaoningChina
| | - Zhijie Li
- Department of PediatricsShengjing Hospital of China Medical UniversityShenyangLiaoningChina
- Medical Research Center, Liaoning Key Laboratory of Research and Application of Animal Models for Environment and Metabolic DiseasesShengjing Hospital of China Medical UniversityShenyangLiaoningChina
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Carretero VJ, Ramos E, Segura-Chama P, Hernández A, Baraibar AM, Álvarez-Merz I, Muñoz FL, Egea J, Solís JM, Romero A, Hernández-Guijo JM. Non-Excitatory Amino Acids, Melatonin, and Free Radicals: Examining the Role in Stroke and Aging. Antioxidants (Basel) 2023; 12:1844. [PMID: 37891922 PMCID: PMC10603966 DOI: 10.3390/antiox12101844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/23/2023] [Accepted: 09/26/2023] [Indexed: 10/29/2023] Open
Abstract
The aim of this review is to explore the relationship between melatonin, free radicals, and non-excitatory amino acids, and their role in stroke and aging. Melatonin has garnered significant attention in recent years due to its diverse physiological functions and potential therapeutic benefits by reducing oxidative stress, inflammation, and apoptosis. Melatonin has been found to mitigate ischemic brain damage caused by stroke. By scavenging free radicals and reducing oxidative damage, melatonin may help slow down the aging process and protect against age-related cognitive decline. Additionally, non-excitatory amino acids have been shown to possess neuroprotective properties, including antioxidant and anti-inflammatory in stroke and aging-related conditions. They can attenuate oxidative stress, modulate calcium homeostasis, and inhibit apoptosis, thereby safeguarding neurons against damage induced by stroke and aging processes. The intracellular accumulation of certain non-excitatory amino acids could promote harmful effects during hypoxia-ischemia episodes and thus, the blockade of the amino acid transporters involved in the process could be an alternative therapeutic strategy to reduce ischemic damage. On the other hand, the accumulation of free radicals, specifically mitochondrial reactive oxygen and nitrogen species, accelerates cellular senescence and contributes to age-related decline. Recent research suggests a complex interplay between melatonin, free radicals, and non-excitatory amino acids in stroke and aging. The neuroprotective actions of melatonin and non-excitatory amino acids converge on multiple pathways, including the regulation of calcium homeostasis, modulation of apoptosis, and reduction of inflammation. These mechanisms collectively contribute to the preservation of neuronal integrity and functions, making them promising targets for therapeutic interventions in stroke and age-related disorders.
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Affiliation(s)
- Victoria Jiménez Carretero
- Department of Pharmacology and Therapeutic, Teófilo Hernando Institute, Faculty of Medicine, Universidad Autónoma de Madrid, Av. Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Eva Ramos
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Complutense University of Madrid, 28040 Madrid, Spain
| | - Pedro Segura-Chama
- Investigador por México-CONAHCYT, Instituto Nacional de Psiquiatría "Ramón de la Fuente Muñiz", Calzada México-Xochimilco 101, Huipulco, Tlalpan, Mexico City 14370, Mexico
| | - Adan Hernández
- Institute of Neurobiology, Universidad Nacional Autónoma of México, Juriquilla, Santiago de Querétaro 76230, Querétaro, Mexico
| | - Andrés M Baraibar
- Department of Neurosciences, Universidad del País Vasco UPV/EHU, Achucarro Basque Center for Neuroscience, Barrio Sarriena, s/n, 48940 Leioa, Spain
| | - Iris Álvarez-Merz
- Department of Pharmacology and Therapeutic, Teófilo Hernando Institute, Faculty of Medicine, Universidad Autónoma de Madrid, Av. Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Francisco López Muñoz
- Faculty of Health Sciences, University Camilo José Cela, C/Castillo de Alarcón 49, Villanueva de la Cañada, 28692 Madrid, Spain
- Neuropsychopharmacology Unit, Hospital 12 de Octubre Research Institute (i + 12), Avda. Córdoba, s/n, 28041 Madrid, Spain
| | - Javier Egea
- Molecular Neuroinflammation and Neuronal Plasticity Research Laboratory, Hospital Universitario Santa Cristina, Health Research Institute, Hospital Universitario de la Princesa, 28006 Madrid, Spain
| | - José M Solís
- Neurobiology-Research Service, Hospital Ramón y Cajal, Carretera de Colmenar Viejo, Km. 9, 28029 Madrid, Spain
| | - Alejandro Romero
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Complutense University of Madrid, 28040 Madrid, Spain
| | - Jesús M Hernández-Guijo
- Department of Pharmacology and Therapeutic, Teófilo Hernando Institute, Faculty of Medicine, Universidad Autónoma de Madrid, Av. Arzobispo Morcillo 4, 28029 Madrid, Spain
- Ramón y Cajal Institute for Health Research (IRYCIS), Hospital Ramón y Cajal, Carretera de Colmenar Viejo, Km. 9, 28029 Madrid, Spain
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Taurino G, Chiu M, Bianchi MG, Griffini E, Bussolati O. The SLC38A5/SNAT5 amino acid transporter: from pathophysiology to pro-cancer roles in the tumor microenvironment. Am J Physiol Cell Physiol 2023; 325:C550-C562. [PMID: 37458433 DOI: 10.1152/ajpcell.00169.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/11/2023] [Accepted: 07/11/2023] [Indexed: 08/09/2023]
Abstract
SLC38A5/SNAT5 is a system N transporter that can mediate net inward or outward transmembrane fluxes of neutral amino acids coupled with Na+ (symport) and H+ (antiport). Its preferential substrates are not only amino acids with side chains containing amide (glutamine and asparagine) or imidazole (histidine) groups, but also serine, glycine, and alanine are transported by the carrier. Expressed in the pancreas, intestinal tract, brain, liver, bone marrow, and placenta, it is regulated at mRNA and protein levels by mTORC1 and WNT/β-catenin pathways, and it is sensitive to pH, nutritional stress, inflammation, and hypoxia. SNAT5 expression has been found to be altered in pathological conditions such as chronic inflammatory diseases, gestational complications, chronic metabolic acidosis, and malnutrition. Growing experimental evidence shows that SNAT5 is overexpressed in several types of cancer cells. Moreover, recently published results indicate that SNAT5 expression in stromal cells can support the metabolic exchanges occurring in the tumor microenvironment of asparagine-auxotroph tumors. We review the functional role of the SNAT5 transporter in pathophysiology and propose that, due to its peculiar operational and regulatory features, SNAT5 may play important pro-cancer roles when expressed either in neoplastic or in stromal cells of glutamine-auxotroph tumors.NEW & NOTEWORTHY The transporter SLC38A5/SNAT5 provides net influx or efflux of glutamine, asparagine, and serine. These amino acids are of particular metabolic relevance in several conditions. Changes in transporter expression or activity have been described in selected types of human cancers, where SNAT5 can mediate amino acid exchanges between tumor and stromal cells, thus providing a potential therapeutic target. This is the first review that recapitulates the characteristics and roles of the transporter in physiology and pathology.
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Affiliation(s)
- Giuseppe Taurino
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
- MRH-Microbiome Research Hub, University of Parma, Parma, Italy
| | - Martina Chiu
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Massimiliano G Bianchi
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
- MRH-Microbiome Research Hub, University of Parma, Parma, Italy
| | - Erika Griffini
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Ovidio Bussolati
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
- MRH-Microbiome Research Hub, University of Parma, Parma, Italy
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Lindberg FA, Nordenankar K, Forsberg EC, Fredriksson R. SLC38A10 Deficiency in Mice Affects Plasma Levels of Threonine and Histidine in Males but Not in Females: A Preliminary Characterization Study of SLC38A10−/− Mice. Genes (Basel) 2023; 14:genes14040835. [PMID: 37107593 PMCID: PMC10138244 DOI: 10.3390/genes14040835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/23/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023] Open
Abstract
Solute carriers belong to the biggest group of transporters in the human genome, but more knowledge is needed to fully understand their function and possible role as therapeutic targets. SLC38A10, a poorly characterized solute carrier, is preliminary characterized here. By using a knockout mouse model, we studied the biological effects of SLC38A10 deficiency in vivo. We performed a transcriptomic analysis of the whole brain and found seven differentially expressed genes in SLC38A10-deficient mice (Gm48159, Nr4a1, Tuba1c, Lrrc56, mt-Tp, Hbb-bt and Snord116/9). By measuring amino acids in plasma, we found lower levels of threonine and histidine in knockout males, whereas no amino acid levels were affected in females, suggesting that SLC38A10−/− might affect sexes differently. Using RT-qPCR, we investigated the effect of SLC38A10 deficiency on mRNA expression of other SLC38 members, Mtor and Rps6kb1 in the brain, liver, lung, muscle, and kidney, but no differences were found. Relative telomere length measurement was also taken, as a marker for cellular age, but no differences were found between the genotypes. We conclude that SLC38A10 might be important for keeping amino acid homeostasis in plasma, at least in males, but no major effects were seen on transcriptomic expression or telomere length in the whole brain.
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Sennoune SR, Nandagopal GD, Ramachandran S, Mathew M, Sivaprakasam S, Jaramillo-Martinez V, Bhutia YD, Ganapathy V. Potent Inhibition of Macropinocytosis by Niclosamide in Cancer Cells: A Novel Mechanism for the Anticancer Efficacy for the Antihelminthic. Cancers (Basel) 2023; 15:759. [PMID: 36765717 PMCID: PMC9913174 DOI: 10.3390/cancers15030759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/17/2023] [Accepted: 01/23/2023] [Indexed: 01/28/2023] Open
Abstract
Niclosamide, a drug used to treat tapeworm infection, possesses anticancer effects by interfering with multiple signaling pathways. Niclosamide also causes intracellular acidification. We have recently discovered that the amino acid transporter SLC38A5, an amino acid-dependent Na+/H+ exchanger, activates macropinocytosis in cancer cells via amino acid-induced intracellular alkalinization. Therefore, we asked whether niclosamide will block basal and SLC38A5-mediated macropinocytosis via intracellular acidification. We monitored macropinocytosis in pancreatic and breast cancer cells using TMR-dextran and the function of SLC38A5 by measuring Li+-stimulated serine uptake. The peptide transporter activity was measured by the uptake of glycylsarcosine. Treatment of the cancer cells with niclosamide caused intracellular acidification. The drug blocked basal and serine-induced macropinocytosis with differential potency, with an EC50 of ~5 μM for the former and ~0.4 μM for the latter. The increased potency for amino acid-mediated macropinocytosis is due to direct inhibition of SLC38A5 by niclosamide in addition to the ability of the drug to cause intracellular acidification. The drug also inhibited the activity of the H+-coupled peptide transporter. We conclude that niclosamide induces nutrient starvation in cancer cells by blocking macropinocytosis, SLC38A5 and the peptide transporter. These studies uncover novel, hitherto unknown, mechanisms for the anticancer efficacy of this antihelminthic.
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Affiliation(s)
- Souad R. Sennoune
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | | | - Sabarish Ramachandran
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Marilyn Mathew
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Sathish Sivaprakasam
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Valeria Jaramillo-Martinez
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Yangzom D. Bhutia
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Vadivel Ganapathy
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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7
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Lindberg FA, Roman E, Fredriksson R. Behavioral profiling of SLC38A10 knockout mice using the multivariate concentric square field TM test. Front Behav Neurosci 2022; 16:987037. [PMID: 36620864 PMCID: PMC9815452 DOI: 10.3389/fnbeh.2022.987037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022] Open
Abstract
Introduction SLC38A10 is a gene that encodes the SLC38A10 protein, also known as SNAT10. The SLC38 family is evolutionary old, and SLC38A10 is one of the oldest members of the family. It is ubiquitously expressed, and its substrates are glutamine, glutamate, alanine, aspartate, and serine. However, little is known about its biological importance. Methods In the current study, an SLC38A10 knockout mouse was run in the multivariate concentric square field TM (MCSF) test. The MCSF test gives the mouse a choice of areas to explore; sheltered areas, elevated and illuminated areas, or open spaces, and a behavioral profile is obtained. The multivariate data obtained were analyzed (i) for each parameter, (ii) parameters grouped into functional categories, and (iii) with a principal component analysis. Results In the trend analysis, knockout mice had a decreased exploratory behavior compared to controls but did not show a distinct grouping in the principal component analysis. Discussion There was not a pronounced difference in the behavioral profile in SLC38A10 knockout mice compared to their wild-type controls, although subtle alterations in zones associated with exploratory behavior and risk assessment in female and male knockout mice, respectively, could be observed. These results imply that a loss of function of the SLC38A10 protein in mice does not drastically alter behavior in the MSCF test.
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Affiliation(s)
- Frida A. Lindberg
- Department of Pharmaceutical Biosciences, Molecular Neuropharmacology, Uppsala University, Uppsala, Sweden,*Correspondence: Frida A. Lindberg,
| | - Erika Roman
- Neuropharmacology and Addiction, Uppsala University, Uppsala, Sweden,Division of Anatomy and Physiology, Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Robert Fredriksson
- Department of Pharmaceutical Biosciences, Molecular Neuropharmacology, Uppsala University, Uppsala, Sweden
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Lindberg FA, Nordenankar K, Fredriksson R. SLC38A10 Knockout Mice Display a Decreased Body Weight and an Increased Risk-Taking Behavior in the Open Field Test. Front Behav Neurosci 2022; 16:840987. [PMID: 35677577 PMCID: PMC9169716 DOI: 10.3389/fnbeh.2022.840987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 03/21/2022] [Indexed: 11/17/2022] Open
Abstract
The solute carrier 38 family (SLC38) is a family of 11 members. The most common substrate among these are alanine and glutamine, and members are present in a wide range of tissues with important functions for several biological processes, such as liver and brain function. Some of these transporters are better characterized than others and, in this paper, a behavioral characterization of SLC38A10−/− mice was carried out. A battery of tests for general activity, emotionality, motor function, and spatial memory was used. Among these tests, the elevated plus maze, Y-maze, marble burying and challenging beam walk have not been tested on the SLC38A10−/− mice previously, while the open field and the rotarod tests have been performed by the International Mouse Phenotyping Consortium (IMPC). Unlike the results from IMPC, the results from this study showed that SLC38A10−/− mice spend less time in the wall zone in the open field test than WT mice, implying that SLC38A10-deficient mice have an increased explorative behavior, which suggests an important function of SLC38A10 in brain. The present study also confirmed IMPC's data regarding rotarod performance and weight, showing that SLC38A10−/− mice do not have an affected motor coordination impairment and have a lower body weight than both SLC38A10+/− and SLC38A10+/+ mice. These results imply that a complete deficiency of the SLC38A10 protein might affect body weight homeostasis, but the underlying mechanisms needs to be studied further.
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Chiu M, Taurino G, Dander E, Bardelli D, Fallati A, Andreoli R, Bianchi MG, Carubbi C, Pozzi G, Galuppo L, Mirandola P, Rizzari C, Tardito S, Biondi A, D’Amico G, Bussolati O. ALL blasts drive primary mesenchymal stromal cells to increase asparagine availability during asparaginase treatment. Blood Adv 2021; 5:5164-5178. [PMID: 34614505 PMCID: PMC9153005 DOI: 10.1182/bloodadvances.2020004041] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 09/01/2021] [Indexed: 11/26/2022] Open
Abstract
Mechanisms underlying the resistance of acute lymphoblastic leukemia (ALL) blasts to l-asparaginase are still incompletely known. Here we demonstrate that human primary bone marrow mesenchymal stromal cells (MSCs) successfully adapt to l-asparaginase and markedly protect leukemic blasts from the enzyme-dependent cytotoxicity through an amino acid trade-off. ALL blasts synthesize and secrete glutamine, thus increasing extracellular glutamine availability for stromal cells. In turn, MSCs use glutamine, either synthesized through glutamine synthetase (GS) or imported, to produce asparagine, which is then extruded to sustain asparagine-auxotroph leukemic cells. GS inhibition prevents mesenchymal cells adaptation to l-asparaginase, lowers glutamine secretion by ALL blasts, and markedly hinders the protection exerted by MSCs on leukemic cells. The pro-survival amino acid exchange is hindered by the inhibition or silencing of the asparagine efflux transporter SNAT5, which is induced in mesenchymal cells by ALL blasts. Consistently, primary MSCs from ALL patients express higher levels of SNAT5 (P < .05), secrete more asparagine (P < .05), and protect leukemic blasts (P < .05) better than MSCs isolated from healthy donors. In conclusion, ALL blasts arrange a pro-leukemic amino acid trade-off with bone marrow mesenchymal cells, which depends on GS and SNAT5 and promotes leukemic cell survival during l-asparaginase treatment.
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Affiliation(s)
- Martina Chiu
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Giuseppe Taurino
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Erica Dander
- Centro Ricerca Tettamanti, Pediatric Department, University of Milano-Bicocca, Fondazione MBBM, Monza, Italy
| | - Donatella Bardelli
- Centro Ricerca Tettamanti, Pediatric Department, University of Milano-Bicocca, Fondazione MBBM, Monza, Italy
| | - Alessandra Fallati
- Centro Ricerca Tettamanti, Pediatric Department, University of Milano-Bicocca, Fondazione MBBM, Monza, Italy
| | - Roberta Andreoli
- Laboratory of Industrial Toxicology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Massimiliano G. Bianchi
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Cecilia Carubbi
- Laboratory of Anatomy and Histology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Giulia Pozzi
- Laboratory of Anatomy and Histology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Laura Galuppo
- Laboratory of Anatomy and Histology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Prisco Mirandola
- Laboratory of Anatomy and Histology, Department of Medicine and Surgery, University of Parma, Parma, Italy
| | - Carmelo Rizzari
- Pediatric Hematology-Oncology Unit, University of Milano-Bicocca, MBBM Foundation, ASST Monza, Monza, Italy
| | - Saverio Tardito
- Cancer Research UK Beatson Institute, Glasgow, United Kingdom; and
- Institute of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Andrea Biondi
- Pediatric Hematology-Oncology Unit, University of Milano-Bicocca, MBBM Foundation, ASST Monza, Monza, Italy
| | - Giovanna D’Amico
- Centro Ricerca Tettamanti, Pediatric Department, University of Milano-Bicocca, Fondazione MBBM, Monza, Italy
| | - Ovidio Bussolati
- Laboratory of General Pathology, Department of Medicine and Surgery, University of Parma, Parma, Italy
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Jung JH, Loeken MR. Diabetic Embryopathy Susceptibility in Mice Is Associated with Differential Dependence on Glucosamine and Modulation of High Glucose-Induced Oxidative Stress. Antioxidants (Basel) 2021; 10:antiox10081156. [PMID: 34439404 PMCID: PMC8388881 DOI: 10.3390/antiox10081156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/15/2021] [Accepted: 07/18/2021] [Indexed: 11/16/2022] Open
Abstract
The high KM glucose transporter, GLUT2 (SLC2A2), is expressed by embryos and causes high rates of glucose transport during maternal hyperglycemic episodes in diabetic pregnancies and causes congenital malformations (diabetic embryopathy). GLUT2 is also a low KM transporter of the amino sugar, glucosamine (GlcN), which enters the hexosamine biosynthetic pathway (HBP) and provides substrate for glycosylation reactions. Exogenous GlcN also increases activity of the pentose phosphate pathway (PPP), which increases production of NADPH reducing equivalents. GLUT2-transported GlcN is inhibited by high glucose concentrations. Not all mouse strains are susceptible to diabetic embryopathy. The aim of this study was to test the hypothesis that susceptibility to diabetic embryopathy is related to differential dependence on exogenous GlcN for glycosylation or stimulation of the PPP. We tested this using murine embryonic stem cell (ESC) lines that were derived from embryopathy-susceptible FVB/NJ (FVB), and embryopathy-resistant C57Bl/6J (B6), embryos in the presence of low or high glucose, and in the presence or absence of GlcN. There were no significant differences in Glut2 expression, or of glucose or GlcN transport, between FVB and B6 ESC. GlcN effects on growth and incorporation into glycoproteins indicated that FVB ESC are more dependent on exogenous GlcN than are B6 ESC. GlcN stimulated PPP activity in FVB but not in B6 ESC. High glucose induced oxidative stress in FVB ESC but not in B6 ESC. These results indicate that FVB embryos are more dependent on exogenous GlcN for glycosylation, but also for stimulation of the PPP and NADPH production, than are B6 embryos, thereby rendering FVB embryos more susceptible to high glucose to induce oxidative stress.
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11
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Hamdani EH, Popek M, Frontczak-Baniewicz M, Utheim TP, Albrecht J, Zielińska M, Chaudhry FA. Perturbation of astroglial Slc38 glutamine transporters by NH 4 + contributes to neurophysiologic manifestations in acute liver failure. FASEB J 2021; 35:e21588. [PMID: 34169573 DOI: 10.1096/fj.202001712rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 03/17/2021] [Accepted: 03/25/2021] [Indexed: 02/07/2023]
Abstract
Ammonia is considered the main pathogenic toxin in hepatic encephalopathy (HE). However, the molecular mechanisms involved have been disputed. As altered glutamatergic and GABAergic neurotransmission has been reported in HE, we investigated whether four members of the solute carrier 38 (Slc38) family of amino acid transporters-involved in the replenishment of glutamate and GABA-contribute to ammonia neurotoxicity in HE. We show that ammonium ion exerts multiple actions on the Slc38 transporters: It competes with glutamine for the binding to the system N transporters Slc38a3 and Slc38a5, consequently inhibiting bidirectional astroglial glutamine transport. It also competes with H+ , Na+ , and K+ for uncoupled permeation through the same transporters, which may perturb astroglial intracellular pH, membrane potential, and K+ -buffering. Knockdown of Slc38a3 in mice results in cerebral cortical edema and disrupted neurotransmitter synthesis mimicking events contributing to HE development. Finally, in a mouse model of acute liver failure (ALF), we demonstrate the downregulation of Slc38a3 protein, impeded astroglial glutamine release, and cytotoxic edema. Altogether, we demonstrate contribution of Slc38 transporters to the ammonia-induced impairment of glutamine recycling between astrocytes and neurons, a phenomenon underlying acute ammonia neurotoxicity in the setting of ALF.
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Affiliation(s)
- El Hassan Hamdani
- Department of Molecular Medicine, University of Oslo (UiO), Oslo, Norway.,Institute of Behavioural Science, Oslo Metropolitan University, Oslo, Norway
| | - Mariusz Popek
- Neurotoxicology Department, Mossakowski Medical Research Institute PAS, Warsaw, Poland
| | | | - Tor Paaske Utheim
- Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.,Department of Plastic and Reconstructive Surgery, Oslo University Hospital, Oslo, Norway
| | - Jan Albrecht
- Neurotoxicology Department, Mossakowski Medical Research Institute PAS, Warsaw, Poland
| | - Magdalena Zielińska
- Neurotoxicology Department, Mossakowski Medical Research Institute PAS, Warsaw, Poland
| | - Farrukh Abbas Chaudhry
- Department of Molecular Medicine, University of Oslo (UiO), Oslo, Norway.,Department of Plastic and Reconstructive Surgery, Oslo University Hospital, Oslo, Norway
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12
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Álvarez-Merz I, Luengo JG, Muñoz MD, Hernández-Guijo JM, Solís JM. Hypoxia-induced depression of synaptic transmission becomes irreversible by intracellular accumulation of non-excitatory amino acids. Neuropharmacology 2021; 190:108557. [PMID: 33848510 DOI: 10.1016/j.neuropharm.2021.108557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 03/10/2021] [Accepted: 04/02/2021] [Indexed: 10/21/2022]
Abstract
The intracellular accumulation of some amino acids (AAs), mainly glutamine, can contribute to brain edema observed during liver failure. We recently demonstrated that individual applications of high concentrations (10 mM) of some non-excitatory AAs increase the electrical resistance of hippocampal slices, indicating cell swelling. Therefore, we pondered whether an AA mixture's application might cause cell swelling at a physiological concentration range. In rat hippocampal slices, we carried out extra- and intracellular electrophysiological recordings and AAs analysis to address this question. We applied a mixture of 19 AAs at their plasmatic concentrations (Plasma solution: Ala, Gly, Gln, His, Ser, Tau, Thr, Arg, Leu, Met, Pro, Val, Asn, Cys, Phe, Ile, Lys, Tyr, and Trp). This solution was afterward divided into two according to the individual AAs at 10 mM concentration inducing synaptic potentiation (Plasma1, containing the first seven AAs of Plasma) or not (Plasma2, with the remaining AAs). Plasma application increased evoked field potentials requiring extracellular chloride. This effect was mimicked by the Plasma1 but not the Plasma2 solution. Plasma1-induced potentiation was independent of changes in release probability, basic electrophysiological membrane properties, and NMDAR activation. AAs in Plasma1 act cooperatively to accumulate intracellularly and to induce synaptic potentiation. In the presence of Plasma1, the reversible synaptic depression caused by a 40-min hypoxia period turned into an irreversible disappearance of synaptic potentials through an NMDAR-dependent mechanism. The presence of a system A transport inhibitor did not block Plasma1-mediated effects. These results indicate that cell swelling, induced by the accumulation of non-excitotoxic AAs through unidentified transporters, might foster deleterious effects produced by hypoxia-ischemia episodes.
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Affiliation(s)
- Iris Álvarez-Merz
- Servicio de Neurobiología-Investigación, Hospital Universitario Ramón y Cajal, IRYCIS, 28034, Madrid, Spain; Departamento de Farmacología y Terapeútica, ITH, Facultad de Medicina, Universidad Autónoma de Madrid, IRYCIS, Avda. Arzobispo Morcillo 4, 28029, Madrid, Spain
| | - Javier G Luengo
- Servicio de Neurobiología-Investigación, Hospital Universitario Ramón y Cajal, IRYCIS, 28034, Madrid, Spain; Departamento de Farmacología y Terapeútica, ITH, Facultad de Medicina, Universidad Autónoma de Madrid, IRYCIS, Avda. Arzobispo Morcillo 4, 28029, Madrid, Spain
| | - María-Dolores Muñoz
- Unidad de Neurología Experimental, Hospital Universitario Ramón y Cajal, IRYCIS, Madrid, 28034, Spain
| | - Jesús M Hernández-Guijo
- Departamento de Farmacología y Terapeútica, ITH, Facultad de Medicina, Universidad Autónoma de Madrid, IRYCIS, Avda. Arzobispo Morcillo 4, 28029, Madrid, Spain
| | - José M Solís
- Servicio de Neurobiología-Investigación, Hospital Universitario Ramón y Cajal, IRYCIS, 28034, Madrid, Spain.
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13
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Zhou Y, Eid T, Hassel B, Danbolt NC. Novel aspects of glutamine synthetase in ammonia homeostasis. Neurochem Int 2020; 140:104809. [DOI: 10.1016/j.neuint.2020.104809] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 02/07/2023]
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14
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Beaudoin JJ, Brouwer KLR, Malinen MM. Novel insights into the organic solute transporter alpha/beta, OSTα/β: From the bench to the bedside. Pharmacol Ther 2020; 211:107542. [PMID: 32247663 PMCID: PMC7480074 DOI: 10.1016/j.pharmthera.2020.107542] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 03/25/2020] [Indexed: 12/14/2022]
Abstract
Organic solute transporter alpha/beta (OSTα/β) is a heteromeric solute carrier protein that transports bile acids, steroid metabolites and drugs into and out of cells. OSTα/β protein is expressed in various tissues, but its expression is highest in the gastrointestinal tract where it facilitates the recirculation of bile acids from the gut to the liver. Previous studies established that OSTα/β is upregulated in liver tissue of patients with extrahepatic cholestasis, obstructive cholestasis, and primary biliary cholangitis (PBC), conditions that are characterized by elevated bile acid concentrations in the liver and/or systemic circulation. The discovery that OSTα/β is highly upregulated in the liver of patients with nonalcoholic steatohepatitis (NASH) further highlights the clinical relevance of this transporter because the incidence of NASH is increasing at an alarming rate with the obesity epidemic. Since OSTα/β is closely linked to the homeostasis of bile acids, and tightly regulated by the nuclear receptor farnesoid X receptor, OSTα/β is a potential drug target for treatment of cholestatic liver disease, and other bile acid-related metabolic disorders such as obesity and diabetes. Obeticholic acid, a semi-synthetic bile acid used to treat PBC, under review for the treatment of NASH, and in development for the treatment of other metabolic disorders, induces OSTα/β. Some drugs associated with hepatotoxicity inhibit OSTα/β, suggesting a possible role for OSTα/β in drug-induced liver injury (DILI). Furthermore, clinical cases of homozygous genetic defects in both OSTα/β subunits resulting in diarrhea and features of cholestasis have been reported. This review article has been compiled to comprehensively summarize the recent data emerging on OSTα/β, recapitulating the available literature on the structure-function and expression-function relationships of OSTα/β, the regulation of this important transporter, the interaction of drugs and other compounds with OSTα/β, and the comparison of OSTα/β with other solute carrier transporters as well as adenosine triphosphate-binding cassette transporters. Findings from basic to more clinically focused research efforts are described and discussed.
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Affiliation(s)
- James J Beaudoin
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Kim L R Brouwer
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Melina M Malinen
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, Kuopio, Finland
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15
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Dependence of the mitochondrial adaptive capacity of hepatocytes on the oxidative substrates availability. UKRAINIAN BIOCHEMICAL JOURNAL 2019. [DOI: 10.15407/ubj91.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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16
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Luengo JG, Muñoz MD, Álvarez-Merz I, Herranz AS, González JC, Martín del Río R, Hernández-Guijo JM, Solís JM. Intracellular accumulation of amino acids increases synaptic potentials in rat hippocampal slices. Amino Acids 2019; 51:1337-1351. [DOI: 10.1007/s00726-019-02771-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 08/11/2019] [Indexed: 12/22/2022]
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17
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Hashim M, Yokoi N, Takahashi H, Gheni G, Okechi OS, Hayami T, Murao N, Hidaka S, Minami K, Mizoguchi A, Seino S. Inhibition of SNAT5 Induces Incretin-Responsive State From Incretin-Unresponsive State in Pancreatic β-Cells: Study of β-Cell Spheroid Clusters as a Model. Diabetes 2018; 67:1795-1806. [PMID: 29954738 DOI: 10.2337/db17-1486] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 06/11/2018] [Indexed: 11/13/2022]
Abstract
β-Cell-β-cell interactions are required for normal regulation of insulin secretion. We previously found that formation of spheroid clusters (called K20-SC) from MIN6-K20 clonal β-cells lacking incretin-induced insulin secretion (IIIS) under monolayer culture (called K20-MC) drastically induced incretin responsiveness. Here we investigated the mechanism by which an incretin-unresponsive state transforms to an incretin-responsive state using K20-SC as a model. Glutamate production by glucose through the malate-aspartate shuttle and cAMP signaling, both of which are critical for IIIS, were enhanced in K20-SC. SC formed from β-cells deficient for aspartate aminotransferase 1, a critical enzyme in the malate-aspartate shuttle, exhibited reduced IIIS. Expression of the sodium-coupled neutral amino acid transporter 5 (SNAT5), which is involved in glutamine transport, was downregulated in K20-SC and pancreatic islets of normal mice but was upregulated in K20-MC and islets of rodent models of obesity and diabetes, both of which exhibit impaired IIIS. Inhibition of SNAT5 significantly increased cellular glutamate content and improved IIIS in islets of these models and in K20-MC. These results suggest that suppression of SNAT5 activity, which results in increased glutamate production, and enhancement of cAMP signaling endows incretin-unresponsive β-cells with incretin responsiveness.
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MESH Headings
- Amino Acid Transport Systems, Neutral/agonists
- Amino Acid Transport Systems, Neutral/antagonists & inhibitors
- Amino Acid Transport Systems, Neutral/genetics
- Amino Acid Transport Systems, Neutral/metabolism
- Animals
- Anti-Obesity Agents/pharmacology
- Cell Communication/drug effects
- Cell Line
- Cells, Cultured
- Clone Cells
- Diabetes Mellitus, Type 2/drug therapy
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Drug Resistance/drug effects
- Gene Expression Regulation/drug effects
- Hypoglycemic Agents/pharmacology
- Incretins/pharmacology
- Insulin-Secreting Cells/drug effects
- Insulin-Secreting Cells/metabolism
- Insulin-Secreting Cells/pathology
- Insulin-Secreting Cells/ultrastructure
- Islets of Langerhans/drug effects
- Islets of Langerhans/metabolism
- Islets of Langerhans/pathology
- Islets of Langerhans/ultrastructure
- Male
- Membrane Transport Modulators/pharmacology
- Mice, Inbred Strains
- Microscopy, Electron, Transmission
- Models, Biological
- Obesity/drug therapy
- Obesity/metabolism
- Obesity/pathology
- RNA Interference
- Spheroids, Cellular/drug effects
- Spheroids, Cellular/metabolism
- Spheroids, Cellular/pathology
- Spheroids, Cellular/ultrastructure
- Tissue Culture Techniques
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Affiliation(s)
- Mahira Hashim
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Norihide Yokoi
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
- Kansai Electric Power Medical Research Institute, Kobe, Japan
| | - Harumi Takahashi
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
- Kansai Electric Power Medical Research Institute, Kobe, Japan
| | - Ghupurjan Gheni
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Oduori S Okechi
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tomohide Hayami
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
- Kansai Electric Power Medical Research Institute, Kobe, Japan
- Division of Diabetes, Department of Internal Medicine, Aichi Medical University, Nagakute, Japan
| | - Naoya Murao
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Shihomi Hidaka
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kohtaro Minami
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Akira Mizoguchi
- Department of Neural Regeneration and Cell Communication, Mie University Graduate School of Medicine, Tsu, Japan
| | - Susumu Seino
- Division of Molecular and Metabolic Medicine, Kobe University Graduate School of Medicine, Kobe, Japan
- Kansai Electric Power Medical Research Institute, Kobe, Japan
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18
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Jensen VF, Mølck AM, Lykkesfeldt J, Bøgh IB. Effect of maternal hypoglycaemia during gestation on materno-foetal nutrient transfer and embryo-foetal development: Evidence from experimental studies focused primarily on the rat. Reprod Toxicol 2018; 77:1-24. [DOI: 10.1016/j.reprotox.2018.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 12/07/2017] [Accepted: 01/30/2018] [Indexed: 01/14/2023]
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19
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Werner A, Koschke M, Leuchtner N, Luckner-Minden C, Habermeier A, Rupp J, Heinrich C, Conradi R, Closs EI, Munder M. Reconstitution of T Cell Proliferation under Arginine Limitation: Activated Human T Cells Take Up Citrulline via L-Type Amino Acid Transporter 1 and Use It to Regenerate Arginine after Induction of Argininosuccinate Synthase Expression. Front Immunol 2017; 8:864. [PMID: 28791021 PMCID: PMC5523021 DOI: 10.3389/fimmu.2017.00864] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 07/07/2017] [Indexed: 11/13/2022] Open
Abstract
In the tumor microenvironment, arginine is metabolized by arginase-expressing myeloid cells. This arginine depletion profoundly inhibits T cell functions and is crucially involved in tumor-induced immunosuppression. Reconstitution of adaptive immune functions in the context of arginase-mediated tumor immune escape is a promising therapeutic strategy to boost the immunological antitumor response. Arginine can be recycled in certain mammalian tissues from citrulline via argininosuccinate (ASA) in a two-step enzymatic process involving the enzymes argininosuccinate synthase (ASS) and argininosuccinate lyase (ASL). Here, we demonstrate that anti-CD3/anti-CD28-activated human primary CD4+ and CD8+ T cells upregulate ASS expression in response to low extracellular arginine concentrations, while ASL is expressed constitutively. ASS expression peaked under moderate arginine restriction (20 µM), but no relevant induction was detectable in the complete absence of extracellular arginine. The upregulated ASS correlated with a reconstitution of T cell proliferation upon supplementation of citrulline, while the suppressed production of IFN-γ was refractory to citrulline substitution. In contrast, ASA reconstituted proliferation and cytokine synthesis even in the complete absence of arginine. By direct quantification of intracellular metabolites we show that activated primary human T cells import citrulline but only metabolize it further to ASA and arginine when ASS is expressed in the context of low amounts of extracellular arginine. We then clarify that citrulline transport is largely mediated by the L-type amino acid transporter 1 (LAT1), induced upon human T cell activation. Upon siRNA-mediated knockdown of LAT1, activated T cells lost the ability to import citrulline. These data underline the potential of citrulline substitution as a promising pharmacological way to treat immunosuppression in settings of arginine deprivation.
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Affiliation(s)
- Anke Werner
- Third Department of Medicine (Hematology, Oncology, and Pneumology), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.,Department of Pharmacology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Miriam Koschke
- Third Department of Medicine (Hematology, Oncology, and Pneumology), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Nadine Leuchtner
- Third Department of Medicine (Hematology, Oncology, and Pneumology), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Claudia Luckner-Minden
- Third Department of Medicine (Hematology, Oncology, and Pneumology), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Alice Habermeier
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Johanna Rupp
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Christin Heinrich
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Roland Conradi
- Transfusion Center, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Ellen I Closs
- Department of Pharmacology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Markus Munder
- Third Department of Medicine (Hematology, Oncology, and Pneumology), University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.,Research Center for Immunotherapy, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
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20
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Kim J, Okamoto H, Huang Z, Anguiano G, Chen S, Liu Q, Cavino K, Xin Y, Na E, Hamid R, Lee J, Zambrowicz B, Unger R, Murphy AJ, Xu Y, Yancopoulos GD, Li WH, Gromada J. Amino Acid Transporter Slc38a5 Controls Glucagon Receptor Inhibition-Induced Pancreatic α Cell Hyperplasia in Mice. Cell Metab 2017; 25:1348-1361.e8. [PMID: 28591637 PMCID: PMC8206958 DOI: 10.1016/j.cmet.2017.05.006] [Citation(s) in RCA: 132] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 03/09/2017] [Accepted: 05/21/2017] [Indexed: 12/22/2022]
Abstract
Glucagon supports glucose homeostasis by stimulating hepatic gluconeogenesis, in part by promoting the uptake and conversion of amino acids into gluconeogenic precursors. Genetic disruption or pharmacologic inhibition of glucagon signaling results in elevated plasma amino acids and compensatory glucagon hypersecretion involving expansion of pancreatic α cell mass. Recent findings indicate that hyperaminoacidemia triggers pancreatic α cell proliferation via an mTOR-dependent pathway. We confirm and extend these findings by demonstrating that glucagon pathway blockade selectively increases expression of the sodium-coupled neutral amino acid transporter Slc38a5 in a subset of highly proliferative α cells and that Slc38a5 controls the pancreatic response to glucagon pathway blockade; most notably, mice deficient in Slc38a5 exhibit markedly decreased α cell hyperplasia to glucagon pathway blockade-induced hyperaminoacidemia. These results show that Slc38a5 is a key component of the feedback circuit between glucagon receptor signaling in the liver and amino-acid-dependent regulation of pancreatic α cell mass in mice.
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Affiliation(s)
- Jinrang Kim
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA
| | - Haruka Okamoto
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA
| | - ZhiJiang Huang
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA
| | - Guillermo Anguiano
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA
| | - Shiuhwei Chen
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA
| | - Qing Liu
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA
| | - Katie Cavino
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA
| | - Yurong Xin
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA
| | - Erqian Na
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA
| | - Rachid Hamid
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA
| | - Joseph Lee
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA
| | | | - Roger Unger
- Touchstone Center for Diabetes Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA
| | | | - Yan Xu
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA
| | | | - Wen-Hong Li
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
| | - Jesper Gromada
- Regeneron Pharmaceuticals, Inc., Tarrytown, NY 10591, USA.
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21
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Hellsten SV, Hägglund MG, Eriksson MM, Fredriksson R. The neuronal and astrocytic protein SLC38A10 transports glutamine, glutamate, and aspartate, suggesting a role in neurotransmission. FEBS Open Bio 2017; 7:730-746. [PMID: 28593130 PMCID: PMC5458457 DOI: 10.1002/2211-5463.12219] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 03/03/2017] [Accepted: 03/08/2017] [Indexed: 12/21/2022] Open
Abstract
In brain cells, glutamine transporters are vital to monitor and control the levels of glutamate and GABA. There are 11 members of the SLC38 family of amino acid transporters of which eight have been functionally characterized. Here, we report the first histological and functional characterization of the previously orphan member, SLC38A10. We used pairwise global sequence alignments to determine the sequence identity between the SLC38 family members. SLC38A10 was found to share 20–25% transmembrane sequence identity with several family members, and was predicted to have 11 transmembrane helices. SLC38A10 immunostaining was abundant in mouse brain using a custom‐made anti‐SLC38A10 antibody and colocalization of SLC38A10 immunoreactivity with markers for neurons and astrocytes was detected. Using Xenopus laevis oocytes overexpressing SLC38A10, we show that SLC38A10 mediates bidirectional transport of l‐glutamine, l‐alanine, l‐glutamate, and d‐aspartate, and efflux of l‐serine. This profile mostly resembles system A members of the SLC38 family. In conclusion, the bidirectional transport of glutamine, glutamate, and aspartate by SLC38A10, and the immunostaining detected in neurons and astrocytes, suggest that SLC38A10 plays a role in pathways involved in neurotransmission.
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Affiliation(s)
- Sofie V Hellsten
- Department of Pharmaceutical Bioscience, Molecular Neuropharmacology Uppsala University Sweden
| | - Maria G Hägglund
- Department of Neuroscience, Functional Pharmacology Uppsala University Sweden
| | - Mikaela M Eriksson
- Department of Pharmaceutical Bioscience, Molecular Neuropharmacology Uppsala University Sweden
| | - Robert Fredriksson
- Department of Pharmaceutical Bioscience, Molecular Neuropharmacology Uppsala University Sweden
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22
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Todd AC, Marx MC, Hulme SR, Bröer S, Billups B. SNAT3-mediated glutamine transport in perisynaptic astrocytesin situis regulated by intracellular sodium. Glia 2017; 65:900-916. [DOI: 10.1002/glia.23133] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/12/2017] [Accepted: 02/08/2017] [Indexed: 01/16/2023]
Affiliation(s)
- Alison C. Todd
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research; The Australian National University; 131 Garran Road Canberra ACT 2601 Australia
- Centre for Integrative Physiology, School of Biomedical Sciences; University of Edinburgh; Edinburgh EH8 9XD United Kingdom
| | - Mari-Carmen Marx
- Department of Pharmacology; University of Cambridge; Tennis Court Road Cambridge CB2 1BT United Kingdom
| | - Sarah R. Hulme
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research; The Australian National University; 131 Garran Road Canberra ACT 2601 Australia
| | - Stefan Bröer
- Research School of Biology; The Australian National University; Linnaeus Way 134 Canberra ACT 2601 Australia
| | - Brian Billups
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research; The Australian National University; 131 Garran Road Canberra ACT 2601 Australia
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23
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Hakvoort TBM, He Y, Kulik W, Vermeulen JLM, Duijst S, Ruijter JM, Runge JH, Deutz NEP, Koehler SE, Lamers WH. Pivotal role of glutamine synthetase in ammonia detoxification. Hepatology 2017; 65:281-293. [PMID: 27641632 DOI: 10.1002/hep.28852] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 08/18/2016] [Accepted: 09/01/2016] [Indexed: 02/06/2023]
Abstract
UNLABELLED Glutamine synthetase (GS) catalyzes condensation of ammonia with glutamate to glutamine. Glutamine serves, with alanine, as a major nontoxic interorgan ammonia carrier. Elimination of hepatic GS expression in mice causes only mild hyperammonemia and hypoglutaminemia but a pronounced decrease in the whole-body muscle-to-fat ratio with increased myostatin expression in muscle. Using GS-knockout/liver and control mice and stepwise increments of enterally infused ammonia, we show that ∼35% of this ammonia is detoxified by hepatic GS and ∼35% by urea-cycle enzymes, while ∼30% is not cleared by the liver, independent of portal ammonia concentrations ≤2 mmol/L. Using both genetic (GS-knockout/liver and GS-knockout/muscle) and pharmacological (methionine sulfoximine and dexamethasone) approaches to modulate GS activity, we further show that detoxification of stepwise increments of intravenously (jugular vein) infused ammonia is almost totally dependent on GS activity. Maximal ammonia-detoxifying capacity through either the enteral or the intravenous route is ∼160 μmol/hour in control mice. Using stable isotopes, we show that disposal of glutamine-bound ammonia to urea (through mitochondrial glutaminase and carbamoylphosphate synthetase) depends on the rate of glutamine synthesis and increases from ∼7% in methionine sulfoximine-treated mice to ∼500% in dexamethasone-treated mice (control mice, 100%), without difference in total urea synthesis. CONCLUSIONS Hepatic GS contributes to both enteral and systemic ammonia detoxification. Glutamine synthesis in the periphery (including that in pericentral hepatocytes) and glutamine catabolism in (periportal) hepatocytes represents the high-affinity ammonia-detoxifying system of the body. The dependence of glutamine-bound ammonia disposal to urea on the rate of glutamine synthesis suggests that enhancing peripheral glutamine synthesis is a promising strategy to treat hyperammonemia. Because total urea synthesis does not depend on glutamine synthesis, we hypothesize that glutamate dehydrogenase complements mitochondrial ammonia production. (Hepatology 2017;65:281-293).
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Affiliation(s)
- Theodorus B M Hakvoort
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Youji He
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Wim Kulik
- Department of Genetic Metabolic Disease, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jacqueline L M Vermeulen
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Suzanne Duijst
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jan M Ruijter
- Heart Failure Center, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Jurgen H Runge
- Department of Radiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Nicolaas E P Deutz
- Department of General Surgery, Maastricht University, Maastricht, The Netherlands
| | - S Eleonore Koehler
- Department of Anatomy & Embryology, Maastricht University, Maastricht, The Netherlands
| | - Wouter H Lamers
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Anatomy & Embryology, Maastricht University, Maastricht, The Netherlands
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24
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Dolgodilina E, Imobersteg S, Laczko E, Welt T, Verrey F, Makrides V. Brain interstitial fluid glutamine homeostasis is controlled by blood-brain barrier SLC7A5/LAT1 amino acid transporter. J Cereb Blood Flow Metab 2016; 36:1929-1941. [PMID: 26661195 PMCID: PMC5094305 DOI: 10.1177/0271678x15609331] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 08/20/2015] [Accepted: 08/31/2015] [Indexed: 01/26/2023]
Abstract
L-glutamine (Gln) is the most abundant amino acid in plasma and cerebrospinal fluid and a precursor for the main central nervous system excitatory (L-glutamate) and inhibitory (γ-aminobutyric acid (GABA)) neurotransmitters. Concentrations of Gln and 13 other brain interstitial fluid amino acids were measured in awake, freely moving mice by hippocampal microdialysis using an extrapolation to zero flow rate method. Interstitial fluid levels for all amino acids including Gln were ∼5-10 times lower than in cerebrospinal fluid. Although the large increase in plasma Gln by intraperitoneal (IP) injection of 15N2-labeled Gln (hGln) did not increase total interstitial fluid Gln, low levels of hGln were detected in microdialysis samples. Competitive inhibition of system A (SLC38A1&2; SNAT1&2) or system L (SLC7A5&8; LAT1&2) transporters in brain by perfusion with α-(methylamino)-isobutyric acid (MeAIB) or 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH) respectively, was tested. The data showed a significantly greater increase in interstitial fluid Gln upon BCH than MeAIB treatment. Furthermore, brain BCH perfusion also strongly increased the influx of hGln into interstitial fluid following IP injection consistent with transstimulation of LAT1-mediated transendothelial transport. Taken together, the data support the independent homeostatic regulation of amino acids in interstitial fluid vs. cerebrospinal fluid and the role of the blood-brain barrier expressed SLC7A5/LAT1 as a key interstitial fluid gatekeeper.
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Affiliation(s)
- Elena Dolgodilina
- Institute of Physiology, Zurich Center for Integrative Human Physiology (ZIHP) and NCCR Kidney. CH, University of Zurich, Zurich, Switzerland
| | - Stefan Imobersteg
- Division of Psychiatry Research, University of Zurich, Schlieren, Switzerland
| | - Endre Laczko
- Functional Genomic Center Zurich (FGCZ), ETH and University of Zurich, Zurich, Switzerland
| | - Tobias Welt
- Division of Psychiatry Research, University of Zurich, Schlieren, Switzerland
| | - Francois Verrey
- Institute of Physiology, Zurich Center for Integrative Human Physiology (ZIHP) and NCCR Kidney. CH, University of Zurich, Zurich, Switzerland
| | - Victoria Makrides
- Institute of Physiology, Zurich Center for Integrative Human Physiology (ZIHP) and NCCR Kidney. CH, University of Zurich, Zurich, Switzerland
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25
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Bröer A, Rahimi F, Bröer S. Deletion of Amino Acid Transporter ASCT2 (SLC1A5) Reveals an Essential Role for Transporters SNAT1 (SLC38A1) and SNAT2 (SLC38A2) to Sustain Glutaminolysis in Cancer Cells. J Biol Chem 2016; 291:13194-205. [PMID: 27129276 DOI: 10.1074/jbc.m115.700534] [Citation(s) in RCA: 165] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Indexed: 11/06/2022] Open
Abstract
Many cancer cells depend on glutamine as they use the glutaminolysis pathway to generate building blocks and energy for anabolic purposes. As a result, glutamine transporters are essential for cancer growth and are potential targets for cancer chemotherapy with ASCT2 (SLC1A5) being investigated most intensively. Here we show that HeLa epithelial cervical cancer cells and 143B osteosarcoma cells express a set of glutamine transporters including SNAT1 (SLC38A1), SNAT2 (SLC38A2), SNAT4 (SLC38A4), LAT1 (SLC7A5), and ASCT2 (SLC1A5). Net glutamine uptake did not depend on ASCT2 but required expression of SNAT1 and SNAT2. Deletion of ASCT2 did not reduce cell growth but caused an amino acid starvation response and up-regulation of SNAT1 to replace ASCT2 functionally. Silencing of GCN2 in the ASCT2(-/-) background reduced cell growth, showing that a combined targeted approach would inhibit growth of glutamine-dependent cancer cells.
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Affiliation(s)
- Angelika Bröer
- From the Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Farid Rahimi
- From the Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Stefan Bröer
- From the Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
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26
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Bilinsky LM, Reed MC, Nijhout HF. The role of skeletal muscle in liver glutathione metabolism during acetaminophen overdose. J Theor Biol 2015; 376:118-33. [PMID: 25890031 DOI: 10.1016/j.jtbi.2015.04.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/29/2015] [Accepted: 04/06/2015] [Indexed: 01/03/2023]
Abstract
Marked alterations in systemic glutamate-glutamine metabolism characterize the catabolic state, in which there is an increased breakdown and decreased synthesis of skeletal muscle protein. Among these alterations are a greatly increased net release of glutamine (Gln) from skeletal muscle into blood plasma and a dramatic depletion of intramuscular Gln. Understanding the catabolic state is important because a number of pathological conditions with very different etiologies are characterized by its presence; these include major surgery, sepsis, trauma, and some cancers. Acetaminophen (APAP) overdose is also accompanied by dramatic changes in systemic glutamate-glutamine metabolism including large drops in liver glutathione (for which glutamate is a precursor) and plasma Gln. We have constructed a mathematical model of glutamate and glutamine metabolism in rat which includes liver, blood plasma and skeletal muscle. We show that for the normal rat, the model solutions fit experimental data including the diurnal variation in liver glutathione (GSH). We show that for the rat chronically dosed with dexamethasone (an artificial glucocorticoid which induces a catabolic state) the model can be used to explain empirically observed facts such as the linear decline in intramuscular Gln and the drop in plasma glutamine. We show that for the Wistar rat undergoing APAP overdose the model reproduces the experimentally observed rebound of liver GSH to normal levels by the 24-h mark. We show that this rebound is achieved in part by the action of the cystine-glutamate antiporter, an amino acid transporter not normally expressed in liver but induced under conditions of oxidative stress. Finally, we explain why supplementation with Gln, a Glu precursor, assists in the preservation of liver GSH during APAP overdose despite the fact that under normal conditions only Cys is rate-limiting for GSH formation.
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Affiliation(s)
- L M Bilinsky
- Department of Mathematics, Duke University, United States.
| | - M C Reed
- Department of Mathematics, Duke University, United States
| | - H F Nijhout
- Department of Biology, Duke University, United States
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27
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Expression of the System N transporter (SNAT5/SN2) during development indicates its plausible role in glutamatergic neurotransmission. Neurochem Int 2014; 73:166-71. [DOI: 10.1016/j.neuint.2013.11.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 11/20/2013] [Accepted: 11/27/2013] [Indexed: 01/09/2023]
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28
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Liu R, Iadevaia V, Averous J, Taylor PM, Zhang Z, Proud CG. Impairing the production of ribosomal RNA activates mammalian target of rapamycin complex 1 signalling and downstream translation factors. Nucleic Acids Res 2014; 42:5083-96. [PMID: 24526220 PMCID: PMC4005692 DOI: 10.1093/nar/gku130] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Ribosome biogenesis is a key process for maintaining protein synthetic capacity in dividing or growing cells, and requires coordinated production of ribosomal proteins and ribosomal RNA (rRNA), including the processing of the latter. Signalling through mammalian target of rapamycin complex 1 (mTORC1) activates all these processes. Here, we show that, in human cells, impaired rRNA processing, caused by expressing an interfering mutant of BOP1 or by knocking down components of the PeBoW complex elicits activation of mTORC1 signalling. This leads to enhanced phosphorylation of its substrates S6K1 and 4E-BP1, and stimulation of proteins involved in translation initiation and elongation. In particular, we observe both inactivation and downregulation of the eukaryotic elongation factor 2 kinase, which normally inhibits translation elongation. The latter effect involves decreased expression of the eEF2K mRNA. The mRNAs for ribosomal proteins, whose translation is positively regulated by mTORC1 signalling, also remain associated with ribosomes. Therefore, our data demonstrate that disrupting rRNA production activates mTORC1 signalling to enhance the efficiency of the translational machinery, likely to help compensate for impaired ribosome production.
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Affiliation(s)
- Rui Liu
- Centre for Biological Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK, Centre de Recherche en Nutrition Humaine, INRA Clermont-Theix, Unité de Nutrition Humaine, 63122 Ceyrat, France and Division of Molecular Physiology, James Black Centre, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
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29
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The SLC38 family of sodium-amino acid co-transporters. Pflugers Arch 2013; 466:155-72. [PMID: 24193407 DOI: 10.1007/s00424-013-1393-y] [Citation(s) in RCA: 153] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 10/16/2013] [Accepted: 10/20/2013] [Indexed: 12/13/2022]
Abstract
Transporters of the SLC38 family are found in all cell types of the body. They mediate Na(+)-dependent net uptake and efflux of small neutral amino acids. As a result they are particularly expressed in cells that grow actively, or in cells that carry out significant amino acid metabolism, such as liver, kidney and brain. SLC38 transporters occur in membranes that face intercellular space or blood vessels, but do not occur in the apical membrane of absorptive epithelia. In the placenta, they play a significant role in the transfer of amino acids to the foetus. Members of the SLC38 family are highly regulated in response to amino acid depletion, hypertonicity and hormonal stimuli. SLC38 transporters play an important role in amino acid signalling and have been proposed to act as transceptors independent of their transport function. The structure of SLC38 transporters is characterised by the 5 + 5 inverted repeat fold, which is observed in a wide variety of transport proteins.
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30
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Schweikhard ES, Ziegler CM. Amino acid secondary transporters: toward a common transport mechanism. CURRENT TOPICS IN MEMBRANES 2013. [PMID: 23177982 DOI: 10.1016/b978-0-12-394316-3.00001-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Solute carriers (SLC) that transport amino acids are key players in health and diseases in humans. Their prokaryotic relatives are often involved in essential physiological processes in microorganisms, e.g. in homeostasis and acidic/osmotic stress response. High-resolution X-ray structures of the sequence-unrelated amino acid transporters unraveled a striking structural similarity between carriers, which were formerly assigned to different families. The highly conserved fold is characterized by two inverted structural repeats of five transmembrane helices each and indicates common mechanistic transport concepts if not an evolutionary link among a large number of amino acid transporters. Therefore, these transporters are classified now into the structural amino acid-polyamine-organocation superfamily (APCS). The APCS includes among others the mammalian SLC6 transporters and the heterodimeric SLC7/SLC3 transporters. However, it has to be noted that the APCS is not limited entirely to amino acid transporters but contains also transporters for, e.g. amino acid derivatives and sugars. For instance, the betaine-choline-carnitine transporter family of bacterial activity-regulated Na(+)- and H(+)-coupled symporters for glycine betaine and choline is also part of this second largest structural superfamily. The APCS fold provides different possibilities to transport the same amino acid. Arginine can be transported by an H(+)-coupled symport or by antiport mechanism in exchange against agmatine for example. The convergence of the mechanistic concept of transport under comparable physiological conditions allows speculating if structurally unexplored amino acid transporters, e.g. the members of the SLC36 and SLC38 family, belong to the APCS, too. In the kidney, which is an organ that depends critically on the regulated amino acid transport, these different SLC transporters have to work together to account for proper function. Here, we will summarize the basic concepts of Na(+)- and H(+)-coupled amino acid symport and amino acid-product antiport in the light of the respective physiological requirements.
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Affiliation(s)
- Eva S Schweikhard
- Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt, Germany
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31
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Abstract
PURPOSE OF REVIEW We consider recent advances in epithelial amino acid transport physiology and our understanding of the functioning of amino acid transporters as sensors, as well as carriers, of tissue nutrient supplies. RECENT FINDINGS Gut hormones (e.g. leptin) may regulate intestinal amino acid transporter activity by a variety of mechanisms, although the overall functional significance of such regulation is not yet fully understood. Important functional interactions between amino acid transporters and nutrient-signalling pathways which regulate metabolism [e.g. the mammalian target of rapamycin (mTOR)C1 pathway which promotes cell growth] have been revealed in recent studies. Amino acid transporters on endosomal (e.g. lysosomal) membranes may be of unexpected significance as intracellular nutrient sensors. It is also now evident that certain amino acid transporters may have dual receptor-transporter functions and act as 'transceptors' to sense amino acid availability upstream of signal pathways. SUMMARY Increased knowledge on the timescale of the amino acid sensor-signal-effector process(es) should help in the optimization of protein-feeding regimes to gain maximum anabolic effect. New opportunities for nutritional therapy include targeting of amino acid transceptors to promote protein-anabolic signals and mechanisms up-regulating amino acid transporter expression to improve absorptive capacity for nutrients.
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Affiliation(s)
- Nadège Poncet
- Division of Cell Signalling & Immunology, College of Life Sciences, University of Dundee, Sir James Black Centre, Dundee, UK
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32
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Hamdani EH, Gudbrandsen M, Bjørkmo M, Chaudhry FA. The system N transporter SN2 doubles as a transmitter precursor furnisher and a potential regulator of NMDA receptors. Glia 2012; 60:1671-83. [PMID: 22821889 DOI: 10.1002/glia.22386] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 06/14/2012] [Accepted: 06/15/2012] [Indexed: 12/28/2022]
Abstract
Activation of NMDA receptor requires two co-agonists, glutamate and glycine. Despite its intrinsic role in brain functions molecular mechanisms involved in glutamate replenishment and identification of the origin of glycine have eluded characterization. We have performed direct measurements of glycine flux by SN2 (Slc38a5; also known as SNAT5), executed extensive electrophysiological characterization as well as implemented ratiometric analyses to show that SN2 transport resembles SN1 in mechanism but differ in functional implications. We report that rat SN2 mediates electroneutral and bidirectional transport of glutamine and glycine at perisynaptic astroglial membranes. Sophisticated coupled and uncoupled movements of H(+) differentially associate with glutamine and glycine transport by SN2 and regulate pH(i) and the release mode of the transporter. Consequently, SN2 doubles as a transmitter precursor furnisher and a potential regulator of NMDA receptors.
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Affiliation(s)
- El Hassan Hamdani
- The Biotechnology Center and Center for Molecular Biology and Neuroscience, University of Oslo, Blindern, Oslo, Norway
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33
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Wang W, Li Y, Zhang W, Zhang F, Li J. Changes of plasma glutamine concentration and hepatocyte membrane system N transporters expression in early endotoxemia. J Surg Res 2009; 166:290-7. [PMID: 20036385 DOI: 10.1016/j.jss.2009.08.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 08/05/2009] [Accepted: 08/28/2009] [Indexed: 11/18/2022]
Abstract
BACKGROUND Glutamine plays important roles in health and critical illness. During endotoxemia, glutamine metabolism, including its plasma level and transport, changes markedly. Previous studies have demonstrated that system N transporters in hepatocytes play a major role in hepatic glutamine transport. However, little is known about the changes of mRNA and protein expression of system N transporters in hepatocyte plasma membrane. Furthermore, the alteration of plasma glutamine concentration during endotoxemia is still controversial. In this study, we investigated the changes in early endotoxemic rats by intraperitoneal injection of lipopolysaccharide (LPS). MATERIALS AND METHODS Three, 6, 12 mg/kg body weight doses of LPS were injected intraperitoneally to establish the endotoxemic rat model; equal volume of 0.9% saline was used as the control. Before and 2, 4, 6, 12, 24h after injections, plasma glutamine concentration, mRNA, and protein expression of SNAT3 and SNAT5 transporters in hepatocyte plasma membrane were detected by high performance liquid chromatography, real-time PCR, and Western blot, respectively. RESULTS LPS injection resulted in a marked increase of the plasma glutamine concentration from 4 to 12h (3mg/kg) and 2 to 6h (6 mg/kg, 12 mg/kg) after the injection compared with its physiologic level, and a significant decrease in 6, 12 mg/kg groups at 24h. Both the mRNA and protein expression of SNAT3 and SNAT5 were enhanced by LPS in a time- and dose-dependent manner. CONCLUSIONS The plasma glutamine concentration in endotoxemic rat increased transiently during early endotoxemia but subsequently decreased over time. The effect of LPS on system N expression occurs not only at the protein level, but also at the mRNA level. It is reasonable to supplement glutamine for patients with sepsis or endotoxemia begin at 6 to 12h after the development of disease.
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Affiliation(s)
- Weiya Wang
- Department of General Surgery, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu Province, PR China
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34
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Baird FE, Bett KJ, MacLean C, Tee AR, Hundal HS, Taylor PM. Tertiary active transport of amino acids reconstituted by coexpression of System A and L transporters in Xenopus oocytes. Am J Physiol Endocrinol Metab 2009; 297:E822-9. [PMID: 19622785 DOI: 10.1152/ajpendo.00330.2009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The System L transporter facilitates cellular import of large neutral amino acids (AAs) such as Leu, a potent activator of the intracellular target of rapamycin (TOR) pathway, which signals for cell growth. System L is an AA exchanger, proposed to accumulate certain AAs by coupling to dissipation of concentration gradient(s) of exchange substrates generated by secondary active AA transporters such as System A (SNAT2). We addressed the hypothesis that this type of coupling (termed tertiary active transport) acts as an indirect mechanism to extend the range of AA stimulating TOR to those transported by both Systems A and L (e.g., Gln) through downstream enhancement of Leu accumulation. System A overexpression enabled Xenopus oocytes to accumulate substrate AAs (notably Ser, Gln, Ala, Pro, Met; totaling 2.6 nmol/oocyte) from medium containing a physiological AA mixture at plasma concentrations. Net accumulation of System L (4F2hc-xLAT1) substrates from this medium by System L-overexpressing oocytes was increased by 90% (from 0.7 to 1.35 nmol/oocyte; mainly Leu, Ile) when Systems A and L were coexpressed, coincident with a decline in accumulation of specific System A substrates (Gln, Ser, Met), as expected if the latter were also System L substrates and functional coupling of the transport Systems occurred. AA flux coupling was confirmed as trans-stimulation of Leu influx in System L-expressing oocytes by Gln injection (0.5 nmol/oocyte). The observed changes in Leu accumulation are sufficient to activate the TOR pathway in oocytes, although intracellular AA metabolism limits the potential for AA accumulation by tertiary active transport in this system.
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Affiliation(s)
- Fiona E Baird
- Div. of Molecular Physiology, College of Life Sciences, Univ. of Dundee, Dundee, Scotland, UK
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35
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Bröer S. Amino acid transport across mammalian intestinal and renal epithelia. Physiol Rev 2008; 88:249-86. [PMID: 18195088 DOI: 10.1152/physrev.00018.2006] [Citation(s) in RCA: 614] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The transport of amino acids in kidney and intestine is critical for the supply of amino acids to all tissues and the homeostasis of plasma amino acid levels. This is illustrated by a number of inherited disorders affecting amino acid transport in epithelial cells, such as cystinuria, lysinuric protein intolerance, Hartnup disorder, iminoglycinuria, dicarboxylic aminoaciduria, and some other less well-described disturbances of amino acid transport. The identification of most epithelial amino acid transporters over the past 15 years allows the definition of these disorders at the molecular level and provides a clear picture of the functional cooperation between transporters in the apical and basolateral membranes of mammalian epithelial cells. Transport of amino acids across the apical membrane not only makes use of sodium-dependent symporters, but also uses the proton-motive force and the gradient of other amino acids to efficiently absorb amino acids from the lumen. In the basolateral membrane, antiporters cooperate with facilitators to release amino acids without depleting cells of valuable nutrients. With very few exceptions, individual amino acids are transported by more than one transporter, providing backup capacity for absorption in the case of mutational inactivation of a transport system.
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Affiliation(s)
- Stefan Bröer
- School of Biochemistry and Molecular Biology, Australian National University, Canberra, Australian Capital Territory, Australia.
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36
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Evans K, Nasim Z, Brown J, Butler H, Kauser S, Varoqui H, Erickson JD, Herbert TP, Bevington A. Acidosis-sensing glutamine pump SNAT2 determines amino acid levels and mammalian target of rapamycin signalling to protein synthesis in L6 muscle cells. J Am Soc Nephrol 2007; 18:1426-36. [PMID: 17429052 DOI: 10.1681/asn.2006091014] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Wasting of lean tissue as a consequence of metabolic acidosis is a serious problem in patients with chronic renal failure. A possible contributor is inhibition by low pH of the System A (SNAT2) transporter, which carries the amino acid L-glutamine (L-Gln) into muscle cells. The aim of this study was to determine the effect of selective SNAT2 inhibition on intracellular amino acid profiles and amino acid-dependent signaling through mammalian target of rapamycin in L6 skeletal muscle cells. Inhibition of SNAT2 with the selective competitive substrate methylaminoisobutyrate, metabolic acidosis (pH 7.1), or silencing SNAT2 expression with small interfering RNA all depleted intracellular L-Gln. SNAT2 inhibition also indirectly depleted other amino acids whose intracellular concentrations are maintained by the L-Gln gradient across the plasma membrane, notably the anabolic amino acid L-leucine. Consequently, SNAT2 inhibition strongly impaired signaling through mammalian target of rapamycin to ribosomal protein S6 kinase, ribosomal protein S6, and 4E-BP1, leading to impairment of protein synthesis comparable with that induced by rapamycin. It is concluded that even though SNAT2 is only one of several L-Gln transporters in muscle, it may determine intracellular anabolic amino acid levels, regulating the amino acid signaling that affects protein mass, nucleotide/nucleic acid metabolism, and cell growth.
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Affiliation(s)
- Kate Evans
- Department of Infection, Immunity and Inflammation, University of Leicester, John Walls Renal Unit, Leicester General Hospital, Leicester, United Kingdom
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37
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Gebhardt R, Baldysiak-Figiel A, Krügel V, Ueberham E, Gaunitz F. Hepatocellular expression of glutamine synthetase: an indicator of morphogen actions as master regulators of zonation in adult liver. ACTA ACUST UNITED AC 2007; 41:201-66. [PMID: 17368308 DOI: 10.1016/j.proghi.2006.12.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Glutamine synthetase (GS) has long been known to be expressed exclusively in pericentral hepatocytes most proximal to the central veins of liver lobuli. This enzyme as well as its peculiar distribution complementary to the periportal compartment for ureogenesis plays an important role in nitrogen metabolism, particularly in homeostasis of blood levels of ammonium ions and glutamine. Despite this fact and intensive studies in vivo and in vitro, many aspects of the regulation of its activity on the protein and on the genetic level remained enigmatic. Recent experimental advances using transgenic mice and new analytic tools have revealed the fundamental role of morphogens such as wingless-type MMTV integration site family member signals (Wnt), beta-catenin, and adenomatous polyposis coli in the regulation of this particular enzyme. In addition, novel information concerning the structure of transcription factor binding sites within regulatory regions of the GS gene and their interactions with signalling pathways could be collected. In this review we focus on all aspects of the regulation of GS in the liver and demonstrate how the new findings have changed our view of the determinants of liver zonation. What appeared as a simple response of hepatocytes to blood-derived factors and local cellular interactions must now be perceived as a fundamental mechanism of adult tissue patterning by morphogens that were considered mainly as regulators of developmental processes. Though GS may be the most obvious indicator of morphogen action among many other targets, elucidation of the complex regulation of the expression of the GS gene could pave the road for a better understanding of the mechanisms involved in patterning of liver parenchyma. Based on current knowledge we propose a new concept of how morphogens, hormones and other factors may act in concert, in order to restrict gene expression to small subpopulations of one differentiated cell type, the hepatocyte, in different anatomical locations. Although many details of this regulatory network are still missing, and an era of exciting new discoveries is still about to come, it can already be envisioned that similar mechanisms may well be active in other organs contributing to the fine-tuning of organ-specific functions.
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Affiliation(s)
- Rolf Gebhardt
- Institut für Biochemie, Medizinische Fakultät, Universität Leipzig, Johannisallee 30, 04103 Leipzig, Germany.
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Baird F, Pinilla-Tenas J, Ogilvie W, Ganapathy V, Hundal H, Taylor P. Evidence for allosteric regulation of pH-sensitive System A (SNAT2) and System N (SNAT5) amino acid transporter activity involving a conserved histidine residue. Biochem J 2006; 397:369-75. [PMID: 16629640 PMCID: PMC1513278 DOI: 10.1042/bj20060026] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Revised: 04/03/2006] [Accepted: 04/21/2006] [Indexed: 11/17/2022]
Abstract
System A and N amino acid transporters are key effectors of movement of amino acids across the plasma membrane of mammalian cells. These Na+-dependent transporters of the SLC38 gene family are highly sensitive to changes in pH within the physiological range, with transport markedly depressed at pH 7.0. We have investigated the possible role of histidine residues in the transporter proteins in determining this pH-sensitivity. The histidine-modifying agent DEPC (diethyl pyrocarbonate) markedly reduces the pH-sensitivity of SNAT2 and SNAT5 transporters (representative isoforms of System A and N respectively, overexpressed in Xenopus oocytes) in a concentration-dependent manner but does not completely inactivate transport activity. These effects of DEPC were reversed by hydroxylamine and partially blocked in the presence of excess amino acid substrate. DEPC treatment also blocked a reduction in apparent affinity for Na+ (K0.5Na+) of the SNAT2 transporter at low external pH. Mutation of the highly conserved C-terminal histidine residue to alanine in either SNAT2 (H504A) or SNAT5 (H471A) produced a transport phenotype exhibiting reduced, DEPC-resistant pH-sensitivity with no change in K0.5Na+ at low external pH. We suggest that the pH-sensitivity of these structurally related transporters results at least partly from a common allosteric mechanism influencing Na+ binding, which involves an H+-modifier site associated with C-terminal histidine residues.
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Affiliation(s)
- Fiona E. Baird
- *Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Jorge J. Pinilla-Tenas
- *Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - William L. J. Ogilvie
- *Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Vadival Ganapathy
- †Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta, GA 30912, U.S.A
| | - Harinder S. Hundal
- *Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Peter M. Taylor
- *Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
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Onan MC, Fisher JS, Ju JS, Fuchs BC, Bode BP. Type I diabetes affects skeletal muscle glutamine uptake in a fiber-specific manner. Exp Biol Med (Maywood) 2005; 230:606-11. [PMID: 16179728 DOI: 10.1177/153537020523000902] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Skeletal muscle serves as the body's major glutamine repository, and releases glutamine at enhanced rates during diabetes, but whether all muscles are equally affected is unknown. System N(m) activity mediates most trans-sarcolemmal glutamine movement, and although two System N (SN) isoforms have been identified (SN1/sodium-coupled neutral amino acid transporter or System N and A transporters [SNAT]-3; and SN2/SNAT5), their expression in skeletal muscle remains controversial. Here, the impact of Type I diabetes on glutamine uptake and System N transporter expression were examined in fast- and slow-twitch skeletal muscle from spontaneously diabetic (BB/Wor-DP) rats. Net glutamine uptake in fast-twitch fibers was decreased 75%-95%, but enhanced more than 2-fold in slow-twitch muscle from diabetic animals relative to nondiabetic controls. Both SNAT3 and SNAT5 mRNA were expressed in both muscle fiber types and their abundance was unaffected by diabetes. This represents the first report of differential fiber-specific effects of diabetes on skeletal muscle glutamine transport and the co-expression of distinct System N transporters in skeletal muscle.
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Affiliation(s)
- Marie C Onan
- Department of Biology, Saint Louis University, St. Louis, MO 63103-2010, USA
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Abstract
Relative to other neutral amino acid transporters, the expression levels of ASCT2 and LAT1, are coordinately elevated in a wide spectrum of primary human cancers, suggesting that they are frequently co-opted to support the "tumor metabolome". Each has recently been shown to play important roles in the growth and survival of cancer cell lines, making them potential targets for cancer therapy. The properties and putative relationship of these two amino acid exchangers are discussed in the context of their demonstrated utility in cancer biology, including cellular growth and survival signaling and integrated links to the mammalian target-of-rapamycin (mTOR) kinase.
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Affiliation(s)
- Bryan C Fuchs
- Department of Biology, Saint Louis University, MW128, 3507 Laclede Avenue, St. Louis, MO 63103-2010, USA
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