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Hruby Weston A, Teixeira IAMA, Yoder PS, Pilonero T, Hanigan MD. Valine and nonessential amino acids affect bidirectional transport rates of leucine and isoleucine in bovine mammary epithelial cells. J Dairy Sci 2024; 107:2026-2046. [PMID: 37863296 DOI: 10.3168/jds.2023-23447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 09/27/2023] [Indexed: 10/22/2023]
Abstract
A more complete understanding of the mechanisms controlling AA transport in mammary glands of dairy cattle will help identify solutions to increase nitrogen feeding efficiency on farms. It was hypothesized that Ala, Gln, and Gly (NEAAG), which are actively transported into cells and exchanged for all branched-chain AA (BCAA), may stimulate transport of BCAA, and that Val may antagonize transport of the other BCAA due to transporter competition. Thus, we evaluated the effects of varying concentrations of NEAAG and Val on transport and metabolism of the BCAA Ala, Met, Phe, and Thr by bovine mammary epithelial cells. Primary cultures of bovine mammary epithelial cells were assigned to treatments of low (70% of mean in vivo plasma concentrations of lactating dairy cows) and high (200%) concentrations of Val and NEAAG (LVal and LNEAAG, HVal and HNEAAG, respectively) in a 2 × 2 factorial design. Cells were preloaded with treatment media containing [15N]-labeled AA for 24 h. The [15N]-labeled media were replaced with treatment media containing [13C]-labeled AA. Media and cells were harvested from plates at 0, 0.5, 1, 5, 15, 30, 60, and 240 min after application of the [13C]-labeled AA and assessed for [15N]- and [13C]-AA label concentrations. The data were used to derive transport, transamination, irreversible loss, and protein-synthesis fluxes. All Val fluxes, except synthesis of rapidly exchanging tissue protein, increased with the HVal treatment. Interestingly, the rapidly exchanging tissue protein, transamination, and irreversible-loss rate constants decreased with HVal, indicating that the significant flux increases were primarily driven by mass action with the cells resisting the flux increases by downregulating activity. However, the decreases could also reflect saturation of processes that would drive down the mass-action rate constants. This is supported by decreases in the same rate constants for Ile and Leu with HVal. This could be due to either competition for shared transamination and oxidation reactions or a reduction in enzymatic activity. Also, NEAAG did not affect Val fluxes, but influx and efflux rate constants increased for both Val and Leu with HNEAAG, indicating an activating substrate effect. Overall, AA transport rates generally responded concordantly with extracellular concentrations, indicating the transporters are not substrate-saturated within the in vivo range. However, BCAA transamination and oxidation enzymes may be approaching saturation within in vivo ranges. In addition, System L transport activity appeared to be stimulated by as much as 75% with high intracellular concentrations of Ala, Gln, and Gly. High concentrations of Val antagonized transport activity of Ile and Leu by 68% and 15%, respectively, indicating competitive inhibition, but this was only observable at HNEAAG concentrations. The exchange transporters of System L transport 8 of the essential AA that make up approximately 40% of milk protein, so better understanding this transporter is an important step for increased efficiency.
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Affiliation(s)
- A Hruby Weston
- School of Animal Sciences, Virginia Tech, Blacksburg, VA 24060.
| | - I A M A Teixeira
- School of Animal Sciences, Virginia Tech, Blacksburg, VA 24060; Department of Animal, Veterinary, and Food Sciences, University of Idaho, Twin Falls, ID 83303-1827
| | - P S Yoder
- School of Animal Sciences, Virginia Tech, Blacksburg, VA 24060; Perdue AgriBusiness LLC, Salisbury, MD 21804
| | - T Pilonero
- School of Animal Sciences, Virginia Tech, Blacksburg, VA 24060
| | - M D Hanigan
- School of Animal Sciences, Virginia Tech, Blacksburg, VA 24060
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Duarte ME, Parnsen W, Zhang S, Abreu MLT, Kim SW. Low crude protein formulation with supplemental amino acids for its impacts on intestinal health and growth performance of growing-finishing pigs. J Anim Sci Biotechnol 2024; 15:55. [PMID: 38528636 DOI: 10.1186/s40104-024-01015-6] [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: 11/07/2023] [Accepted: 02/14/2024] [Indexed: 03/27/2024] Open
Abstract
BACKGROUND Low crude protein (CP) formulations with supplemental amino acids (AA) are used to enhance intestinal health, reduce costs, minimize environmental impact, and maintain growth performance of pigs. However, extensive reduction of dietary CP can compromise growth performance due to limited synthesis of non-essential AA and limited availability of bioactive compounds from protein supplements even when AA requirements are met. Moreover, implementing a low CP formulation can increase the net energy (NE) content in feeds causing excessive fat deposition. Additional supplementation of functional AA, coupled with low CP formulation could further enhance intestinal health and glucose metabolism, improving nitrogen utilization, and growth performance. Three experiments were conducted to evaluate the effects of low CP formulations with supplemental AA on the intestinal health and growth performance of growing-finishing pigs. METHODS In Exp. 1, 90 pigs (19.7 ± 1.1 kg, 45 barrows and 45 gilts) were assigned to 3 treatments: CON (18.0% CP, supplementing Lys, Met, and Thr), LCP (16.0% CP, supplementing Lys, Met, Thr, Trp, and Val), and LCPT (16.1% CP, LCP + 0.05% SID Trp). In Exp. 2, 72 pigs (34.2 ± 4.2 kg BW) were assigned to 3 treatments: CON (17.7% CP, meeting the requirements of Lys, Met, Thr, and Trp); LCP (15.0% CP, meeting Lys, Thr, Trp, Met, Val, Ile, and Phe); and VLCP (12.8% CP, meeting Lys, Thr, Trp, Met, Val, Ile, Phe, His, and Leu). In Exp. 3, 72 pigs (54.1 ± 5.9 kg BW) were assigned to 3 treatments and fed experimental diets for 3 phases (grower 2, finishing 1, and finishing 2). Treatments were CON (18.0%, 13.8%, 12.7% CP for 3 phases; meeting Lys, Met, Thr, and Trp); LCP (13.5%, 11.4%, 10.4% CP for 3 phases; meeting Lys, Thr, Trp, Met, Val, Ile, and Phe); and LCPG (14.1%, 12.8%, 11.1% CP for 3 phases; LCP + Glu to match SID Glu with CON). All diets had 2.6 Mcal/kg NE. RESULTS In Exp. 1, overall, the growth performance did not differ among treatments. The LCPT increased (P < 0.05) Claudin-1 expression in the duodenum and jejunum. The LCP and LCPT increased (P < 0.05) CAT-1, 4F2hc, and B0AT expressions in the jejunum. In Exp. 2, overall, the VLCP reduced (P < 0.05) G:F and BUN. The LCP and VLCP increased (P < 0.05) the backfat thickness (BFT). In Exp. 3, overall, growth performance and BFT did not differ among treatments. The LCPG reduced (P < 0.05) BUN, whereas increased the insulin in plasma. The LCP and LCPG reduced (P < 0.05) the abundance of Streptococcaceae, whereas the LCP reduced (P < 0.05) Erysipelotrichaceae, and the alpha diversity. CONCLUSIONS When implementing low CP formulation, CP can be reduced by supplementation of Lys, Thr, Met, Trp, Val, and Ile without affecting the growth performance of growing-finishing pigs when NE is adjusted to avoid increased fat deposition. Supplementation of Trp above the requirement or supplementation of Glu in low CP formulation seems to benefit intestinal health as well as improved nitrogen utilization and glucose metabolism.
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Affiliation(s)
- Marcos Elias Duarte
- Department of Animal Science, North Carolina State University, Raleigh, NC, 27695, USA
| | - Wanpuech Parnsen
- Department of Animal Science, North Carolina State University, Raleigh, NC, 27695, USA
| | - Shihai Zhang
- Department of Animal Science, North Carolina State University, Raleigh, NC, 27695, USA
| | - Márvio L T Abreu
- Department of Animal Science, North Carolina State University, Raleigh, NC, 27695, USA
| | - Sung Woo Kim
- Department of Animal Science, North Carolina State University, Raleigh, NC, 27695, USA.
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Kahlhofer J, Teis D. The human LAT1-4F2hc (SLC7A5-SLC3A2) transporter complex: Physiological and pathophysiological implications. Basic Clin Pharmacol Toxicol 2023; 133:459-472. [PMID: 36460306 DOI: 10.1111/bcpt.13821] [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: 09/19/2022] [Revised: 11/24/2022] [Accepted: 11/28/2022] [Indexed: 12/04/2022]
Abstract
LAT1 and 4F2hc form a heterodimeric membrane protein complex, which functions as one of the best characterized amino acid transporters. Since LAT1-4F2hc is required for the efficient uptake of essential amino acids and hormones, it promotes cellular growth, in part, by stimulating mTORC1 (mechanistic target of rapamycin complex 1) signalling and by repressing the integrated stress response (ISR). Gain or loss of LAT1-4F2hc function is associated with cancer, diabetes, and immunological and neurological diseases. Hence, LAT1-4F2hc represents an attractive drug target for disease treatment. Specific targeting of LAT1-4F2hc will be facilitated by the increasingly detailed understanding of its molecular architecture, which provides important concepts for its function and regulation. Here, we summarize (i) structural insights that help to explain how LAT1 and 4F2hc assemble to transport amino acids across membranes, (ii) the role of LAT1-4F2hc in key metabolic signalling pathways, and (iii) how derailing these processes could contribute to diseases.
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Affiliation(s)
- Jennifer Kahlhofer
- Institute for Cell Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - David Teis
- Institute for Cell Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
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Piwarski SA, Salisbury TB. The effects of environmental aryl hydrocarbon receptor ligands on signaling and cell metabolism in cancer. Biochem Pharmacol 2023; 216:115771. [PMID: 37652105 DOI: 10.1016/j.bcp.2023.115771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/18/2023] [Accepted: 08/28/2023] [Indexed: 09/02/2023]
Abstract
Dioxin and dioxin-like compounds are chlorinated organic pollutants formed during the manufacturing of other chemicals. Dioxins are ligands of the aryl hydrocarbon receptor (AHR), that induce AHR-mediated biochemical and toxic responses and are persistent in the environment. 2,3,7,8- tetrachlorodibenzo para dioxin (TCDD) is the prototypical AHR ligand and its effects represent dioxins. TCDD induces toxicity, immunosuppression and is a suspected tumor promoter. The role of TCDD in cancer however is debated and context-dependent. Environmental particulate matter, polycyclic aromatic hydrocarbons, perfluorooctane sulfonamide, endogenous AHR ligands, and cAMP signaling activate AHR through TCDD-independent pathways. The effect of activated AHR in cancer is context-dependent. The ability of FDA-approved drugs to modulate AHR activity has sparked interest in their repurposing for cancer therapy. TCDD by interfering with endogenous pathways, and overstimulating other endogenous pathways influences all stages of cancer. Herein we review signaling mechanisms that activate AHR and mechanisms by which activated AHR modulates signaling in cancer including affected metabolic pathways.
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Affiliation(s)
- Sean A Piwarski
- Duke Cancer Institute, Department of GU Oncology, Duke University Medical Center, 905 South Lasalle Street, Durham, NC 27710, USA.
| | - Travis B Salisbury
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA.
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Abstract
Amino acids derived from protein digestion are important nutrients for the growth and maintenance of organisms. Approximately half of the 20 proteinogenic amino acids can be synthesized by mammalian organisms, while the other half are essential and must be acquired from the nutrition. Absorption of amino acids is mediated by a set of amino acid transporters together with transport of di- and tripeptides. They provide amino acids for systemic needs and for enterocyte metabolism. Absorption is largely complete at the end of the small intestine. The large intestine mediates the uptake of amino acids derived from bacterial metabolism and endogenous sources. Lack of amino acid transporters and peptide transporter delays the absorption of amino acids and changes sensing and usage of amino acids by the intestine. This can affect metabolic health through amino acid restriction, sensing of amino acids, and production of antimicrobial peptides.
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Affiliation(s)
- Stefan Bröer
- Research School of Biology, Australian National University, Canberra, Australia;
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Harris AN, Skankar M, Melanmed M, Batlle D. An Update on Kidney Ammonium Transport Along the Nephron. ADVANCES IN KIDNEY DISEASE AND HEALTH 2023; 30:189-196. [PMID: 36868733 DOI: 10.1053/j.akdh.2022.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 12/14/2022] [Indexed: 03/05/2023]
Abstract
Acid-base homeostasis is critical to the maintenance of normal health. The kidneys have a central role in bicarbonate generation, which occurs through the process of net acid excretion. Renal ammonia excretion is the predominant component of renal net acid excretion under basal conditions and in response to acid-base disturbances. Ammonia produced in the kidney is selectively transported into the urine or the renal vein. The amount of ammonia produced by the kidney that is excreted in the urine varies dramatically in response to physiological stimuli. Recent studies have advanced our understanding of ammonia metabolism's molecular mechanisms and regulation. Ammonia transport has been advanced by recognizing that the specific transport of NH3 and NH4+ by specific membrane proteins is critical to ammonia transport. Other studies show that proximal tubule protein, NBCe1, specifically the A variant, significantly regulates renal ammonia metabolism. This review discusses these critical aspects of the emerging features of ammonia metabolism and transport.
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Affiliation(s)
- Autumn N Harris
- Department of Small Animal Clinical Science, University of Florida College of Veterinary Medicine, Gainesville, FL; Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL.
| | - Mythri Skankar
- Department of Nephrology, Institute of Nephro-urology, Bengaluru, India
| | - Michal Melanmed
- Albert Einstein College of Medicine/ Montefiore Medical Center, Bronx, NY
| | - Daniel Batlle
- Northwestern University Feinberg School of Medicine, Chicago, IL
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Gauthier-Coles G, Fairweather SJ, Bröer A, Bröer S. Do Amino Acid Antiporters Have Asymmetric Substrate Specificity? Biomolecules 2023; 13:biom13020301. [PMID: 36830670 PMCID: PMC9953452 DOI: 10.3390/biom13020301] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/31/2023] [Accepted: 02/03/2023] [Indexed: 02/10/2023] Open
Abstract
Amino acid antiporters mediate the 1:1 exchange of groups of amino acids. Whether substrate specificity can be different for the inward and outward facing conformation has not been investigated systematically, although examples of asymmetric transport have been reported. Here we used LC-MS to detect the movement of 12C- and 13C-labelled amino acid mixtures across the plasma membrane of Xenopus laevis oocytes expressing a variety of amino acid antiporters. Differences of substrate specificity between transporter paralogs were readily observed using this method. Our results suggest that antiporters are largely symmetric, equalizing the pools of their substrate amino acids. Exceptions are the antiporters y+LAT1 and y+LAT2 where neutral amino acids are co-transported with Na+ ions, favouring their import. For the antiporters ASCT1 and ASCT2 glycine acted as a selective influx substrate, while proline was a selective influx substrate of ASCT1. These data show that antiporters can display non-canonical modes of transport.
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Taslimifar M, Faltys M, Kurtcuoglu V, Verrey F, Makrides V. Analysis of L-leucine amino acid transporter species activity and gene expression by human blood brain barrier hCMEC/D3 model reveal potential LAT1, LAT4, B 0AT2 and y +LAT1 functional cooperation. J Cereb Blood Flow Metab 2022; 42:90-103. [PMID: 34427144 PMCID: PMC8721536 DOI: 10.1177/0271678x211039593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In the CNS, amino acid (AA) neurotransmitters and neurotransmitter precursors are subject to tight homeostatic control mediated by blood-brain barrier (BBB) solute carrier amino acid transporters (AATs). Since the BBB is composed of multiple closely apposed cell types and opportunities for human in vivo studies are limited, we used in vitro and computational approaches to investigate human BBB AAT activity and regulation. Quantitative real-time PCR (qPCR) of the human BBB endothelial cell model hCMEC/D3 (D3) was used to determine expression of selected AAT, tight junction (TJ), and signal transduction (ST) genes under various culture conditions. L-leucine uptake data were interrogated with a computational model developed by our group for calculating AAT activity in complex cell cultures. This approach is potentially applicable to in vitro cell culture drug studies where multiple "receptors" may mediate observed responses. Of 7 Leu AAT genes expressed by D3 only the activity of SLC7A5-SLC3A2/LAT1-4F2HC (LAT1), SLC43A2/LAT4 (LAT4) and sodium-dependent AATs, SLC6A15/B0AT2 (B0AT2), and SLC7A7/y+LAT1 (y+LAT1) were calculated to be required for Leu uptake. Therefore, D3 Leu transport may be mediated by a potentially physiologically relevant functional cooperation between the known BBB AAT, LAT1 and obligatory exchange (y+LAT1), facilitative diffusion (LAT4), and sodium symporter (B0AT2) transporters.
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Affiliation(s)
- Mehdi Taslimifar
- The Interface Group, Institute of Physiology, University of Zürich, Zürich, Switzerland.,Epithelial Transport Group, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Martin Faltys
- Epithelial Transport Group, Institute of Physiology, University of Zürich, Zürich, Switzerland.,Department of Intensive Care Medicine, University Hospital, University of Bern, Bern, Switzerland
| | - Vartan Kurtcuoglu
- The Interface Group, Institute of Physiology, University of Zürich, Zürich, Switzerland.,National Center of Competence in Research, Kidney CH, Switzerland
| | - François Verrey
- Epithelial Transport Group, Institute of Physiology, University of Zürich, Zürich, Switzerland.,National Center of Competence in Research, Kidney CH, Switzerland
| | - Victoria Makrides
- The Interface Group, Institute of Physiology, University of Zürich, Zürich, Switzerland.,Epithelial Transport Group, Institute of Physiology, University of Zürich, Zürich, Switzerland.,EIC BioMedical Labs, Norwood, MA, USA
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Kurz A, Seifert J. Factors Influencing Proteolysis and Protein Utilization in the Intestine of Pigs: A Review. Animals (Basel) 2021; 11:3551. [PMID: 34944326 PMCID: PMC8698117 DOI: 10.3390/ani11123551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/03/2021] [Accepted: 12/11/2021] [Indexed: 11/16/2022] Open
Abstract
Pigs are among the most important farm animals for meat production worldwide. In order to meet the amino acid requirements of the animals, pigs rely on the regular intake of proteins and amino acids with their feed. Unfortunately, pigs excrete about two thirds of the used protein, and production of pork is currently associated with a high emission of nitrogen compounds resulting in negative impacts on the environment. Thus, improving protein efficiency in pigs is a central aim to decrease the usage of protein carriers in feed and to lower nitrogen emissions. This is necessary as the supply of plant protein sources is limited by the yield and the cultivable acreage for protein plants. Strategies to increase protein efficiency that go beyond the known feeding options have to be investigated considering the characteristics of the individual animals. This requires a deep understanding of the intestinal processes including enzymatic activities, capacities of amino acid transporters and the microbiome. This review provides an overview of these physiological factors and the respective analyses methods.
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Affiliation(s)
- Alina Kurz
- HoLMIR—Hohenheim Center for Livestock Microbiome Research, University of Hohenheim, 70599 Stuttgart, Germany;
- Institute of Animal Science, University of Hohenheim, Emil-Wolff-Str. 8, 70599 Stuttgart, Germany
| | - Jana Seifert
- HoLMIR—Hohenheim Center for Livestock Microbiome Research, University of Hohenheim, 70599 Stuttgart, Germany;
- Institute of Animal Science, University of Hohenheim, Emil-Wolff-Str. 8, 70599 Stuttgart, Germany
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Mazzulla M, Hodson N, Lees M, Scaife PJ, Smith K, Atherton PJ, Kumbhare D, Moore DR. LAT1 and SNAT2 Protein Expression and Membrane Localization of LAT1 Are Not Acutely Altered by Dietary Amino Acids or Resistance Exercise Nor Positively Associated with Leucine or Phenylalanine Incorporation in Human Skeletal Muscle. Nutrients 2021; 13:nu13113906. [PMID: 34836160 PMCID: PMC8624011 DOI: 10.3390/nu13113906] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/13/2021] [Accepted: 10/22/2021] [Indexed: 12/26/2022] Open
Abstract
The influx of essential amino acids into skeletal muscle is primarily mediated by the large neutral amino acid transporter 1 (LAT1), which is dependent on the glutamine gradient generated by the sodium-dependent neutral amino acid transporter 2 (SNAT2). The protein expression and membrane localization of LAT1 may be influenced by amino acid ingestion and/or resistance exercise, although its acute influence on dietary amino acid incorporation into skeletal muscle protein has not been investigated. In a group design, healthy males consumed a mixed carbohydrate (0.75 g·kg-1) crystalline amino acid (0.25 g·kg-1) beverage enriched to 25% and 30% with LAT1 substrates L-[1-13C]leucine (LEU) and L-[ring-2H5]phenylalanine (PHE), respectively, at rest (FED: n = 7, 23 ± 5 y, 77 ± 4 kg) or after a bout of resistance exercise (EXFED: n = 7, 22 ± 2 y, 78 ± 11 kg). Postprandial muscle biopsies were collected at 0, 120, and 300 min to measure transporter protein expression (immunoblot), LAT1 membrane localization (immunofluorescence), and dietary amino acid incorporation into myofibrillar protein (ΔLEU and ΔPHE). Basal LAT1 and SNAT2 protein contents were correlated with each other (r = 0.55, p = 0.04) but their expression did not change across time in FED or EXFED (all, p > 0.05). Membrane localization of LAT1 did not change across time in FED or EXFED whether measured as outer 1.5 µm intensity or membrane-to-fiber ratio (all, p > 0.05). Basal SNAT2 protein expression was not correlated with ΔLEU or ΔPHE (all, p ≥ 0.05) whereas basal LAT1 expression was negatively correlated with ΔPHE in FED (r = -0.76, p = 0.04) and EXFED (r = -0.81, p = 0.03) but not ΔLEU (p > 0.05). Basal LAT1 membrane localization was not correlated with ΔLEU or ΔPHE (all, p > 0.05). Our results suggest that LAT1/SNAT2 protein expression and LAT1 membrane localization are not influenced by acute anabolic stimuli and do not positively influence the incorporation of dietary amino acids for de novo myofibrillar protein synthesis in healthy young males.
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Affiliation(s)
- Michael Mazzulla
- Department of Exercise Sciences, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON M5S 2C9, Canada; (M.M.); (N.H.); (M.L.)
| | - Nathan Hodson
- Department of Exercise Sciences, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON M5S 2C9, Canada; (M.M.); (N.H.); (M.L.)
| | - Matthew Lees
- Department of Exercise Sciences, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON M5S 2C9, Canada; (M.M.); (N.H.); (M.L.)
| | - Paula J. Scaife
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Centre of Metabolism, Ageing and Physiology, School of Medicine, University of Nottingham, Derby DE22 3DT, UK; (P.J.S.); (K.S.); (P.J.A.)
| | - Kenneth Smith
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Centre of Metabolism, Ageing and Physiology, School of Medicine, University of Nottingham, Derby DE22 3DT, UK; (P.J.S.); (K.S.); (P.J.A.)
| | - Philip J. Atherton
- MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, Centre of Metabolism, Ageing and Physiology, School of Medicine, University of Nottingham, Derby DE22 3DT, UK; (P.J.S.); (K.S.); (P.J.A.)
| | - Dinesh Kumbhare
- Department of Medicine, University of Toronto, Toronto, ON M5S 2C9, Canada;
| | - Daniel R. Moore
- Department of Exercise Sciences, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON M5S 2C9, Canada; (M.M.); (N.H.); (M.L.)
- Correspondence: ; Tel.: +1-(416)-946-4088
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Bröer S, Gauthier-Coles G. Amino Acid Homeostasis in Mammalian Cells with a Focus on Amino Acid Transport. J Nutr 2021; 152:16-28. [PMID: 34718668 PMCID: PMC8754572 DOI: 10.1093/jn/nxab342] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/02/2021] [Accepted: 09/17/2021] [Indexed: 12/12/2022] Open
Abstract
Amino acid homeostasis is maintained by import, export, oxidation, and synthesis of nonessential amino acids, and by the synthesis and breakdown of protein. These processes work in conjunction with regulatory elements that sense amino acids or their metabolites. During and after nutrient intake, amino acid homeostasis is dominated by autoregulatory processes such as transport and oxidation of excess amino acids. Amino acid deprivation triggers processes such as autophagy and the execution of broader transcriptional programs to maintain plasma amino acid concentrations. Amino acid transport plays a crucial role in the absorption of amino acids in the intestine, the distribution of amino acids across cells and organs, the recycling of amino acids in the kidney, and the recycling of amino acids after protein breakdown.
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Romanet S, Aschenbach JR, Pieper R, Zentek J, Htoo JK, Whelan RA, Mastrototaro L. Expression of proposed methionine transporters along the gastrointestinal tract of pigs and their regulation by dietary methionine sources. GENES AND NUTRITION 2021; 16:14. [PMID: 34488623 PMCID: PMC8422629 DOI: 10.1186/s12263-021-00694-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/25/2021] [Indexed: 11/10/2022]
Abstract
BACKGROUND Given the key role of methionine (Met) in biological processes like protein translation, methylation, and antioxidant defense, inadequate Met supply can limit performance. This study investigated the effect of different dietary Met sources on the expression profile of various Met transporters along the gastrointestinal tract (GIT) of pigs. METHODS A total of 27 pigs received a diet supplemented with 0.21% DL-Met, 0.21% L-Met, or 0.31% DL-2-hydroxy-4-(methylthio)butanoic acid (DL-HMTBA). Changes in mRNA expression of B0AT1, ATB0,+, rBAT, ASCT2, IMINO, LAT4, y+LAT1, LAT2, and SNAT2 were evaluated in the oral mucosa, cardia, fundus, pylorus, duodenum, proximal jejunum, middle jejunum, ileum, cecum, proximal colon, and distal colon, complemented by protein expression analysis of B0AT1, ASCT2, LAT2, and LAT4. RESULTS Expression of all investigated transcripts differed significantly along the GIT. B0AT1, rBAT, y+LAT1, LAT2, and LAT4 showed strongest mRNA expression in small intestinal segments. ASCT2, IMINO, and SNAT2 were similarly expressed along the small and large intestines but expression differed in the oral mucosa and stomach. ATB0,+ showed highest mRNA expression in large intestinal tissues, cardia, and pylorus. In pigs fed DL-Met, mRNA expression of ASCT2 was higher than in pigs fed DL-HMTBA in small intestinal tissues and mRNA expression of IMINO was lower than in pigs fed L-Met in large intestinal tissues. Dietary DL-HMTBA induced a stronger mRNA expression of basolateral uptake systems either in the small (LAT2) or large (y+LAT1) intestine. Protein expression of B0AT1 was higher in the middle jejunum and ileum in pigs fed DL-Met when compared with the other Met supplements. LAT4 expression was higher in pigs fed DL-HMTBA when compared with DL-Met (small intestine) and L-Met (small intestine, oral mucosa, and stomach). CONCLUSION A high expression of several Met transporters in small intestinal segments underlines the primary role of these segments in amino acid absorption; however, some Met transporters show high transcript and protein levels also in large intestine, oral mucosa, and stomach. A diet containing DL-Met has potential to increase apical Met transport in the small intestine, whereas a diet containing DL-HMTBA has potential to increase basolateral Met transport in the small intestine and, partly, other gastrointestinal tissues.
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Affiliation(s)
- Stella Romanet
- Institute of Veterinary Physiology, Freie Universität Berlin, Oertzenweg 19b, 14163, Berlin, Germany
| | - Jörg R Aschenbach
- Institute of Veterinary Physiology, Freie Universität Berlin, Oertzenweg 19b, 14163, Berlin, Germany.
| | - Robert Pieper
- Institute of Animal Nutrition, Freie Universität Berlin, Berlin, Germany
| | - Jürgen Zentek
- Institute of Animal Nutrition, Freie Universität Berlin, Berlin, Germany
| | - John K Htoo
- Evonik Operations GmbH, Animal Nutrition Services, Hanau-Wolfgang, Germany
| | - Rose A Whelan
- Evonik Operations GmbH, Animal Nutrition Services, Hanau-Wolfgang, Germany
| | - Lucia Mastrototaro
- Institute of Veterinary Physiology, Freie Universität Berlin, Oertzenweg 19b, 14163, Berlin, Germany
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13
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Marszalek-Grabska M, Walczak K, Gawel K, Wicha-Komsta K, Wnorowska S, Wnorowski A, Turski WA. Kynurenine emerges from the shadows – Current knowledge on its fate and function. Pharmacol Ther 2021; 225:107845. [DOI: 10.1016/j.pharmthera.2021.107845] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 03/29/2021] [Indexed: 12/12/2022]
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14
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Thompson C, Rahman MM, Singh S, Arthur S, Sierra-Bakhshi C, Russell R, Denning K, Sundaram U, Salisbury T. The Adipose Tissue-Derived Secretome (ADS) in Obesity Uniquely Induces L-Type Amino Acid Transporter 1 (LAT1) and mTOR Signaling in Estrogen-Receptor-Positive Breast Cancer Cells. Int J Mol Sci 2021; 22:6706. [PMID: 34201429 PMCID: PMC8268498 DOI: 10.3390/ijms22136706] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/15/2021] [Accepted: 06/17/2021] [Indexed: 01/01/2023] Open
Abstract
Obesity increases the risk of postmenopausal breast cancer (BC). This risk is mediated by obesity-induced changes in the adipose-derived secretome (ADS). The pathogenesis of BC in obesity is stimulated by mTOR hyperactivity. In obesity, leucine might support mTOR hyperactivity. Leucine uptake by BC cells is through L-Type Amino Acid Transporter 1 (LAT1). Our objective was to link obesity-ADS induction of LAT1 to the induction of mTOR signaling. Lean- and obese-ADS were obtained from lean and obese mice, respectively. Breast ADS was obtained from BC patients. Estrogen-receptor-positive BC cells were stimulated with ADS. LAT1 activity was determined by uptake of 3H-leucine. The LAT1/CD98 complex, and mTOR signaling were assayed by Western blot. The LAT1 antagonists, BCH and JPH203, were used to inhibit LAT1. Cell migration and invasion were measured by Transwell assays. The results showed obese-ADS-induced LAT1 activity by increasing transporter affinity for leucine. Consistent with this mechanism, LAT1 and CD98 expression were unchanged. Induction of mTOR by obese-ADS was inhibited by LAT1 antagonists. Breast ADS from patients with BMIs > 30 stimulated BC cell migration and invasiveness. Collectively, our findings show that obese-ADS induction of LAT1 supports mTOR hyperactivity in luminal BC cells.
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Affiliation(s)
- Chelsea Thompson
- Department of Biomedical Sciences and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA; (C.T.); (C.S.-B.)
| | - M Motiur Rahman
- Department of Clinical and Translational Sciences and Appalachian Clinical and Translational Science Institute and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, 1600 Medical Center Drive, Huntington, WV 25701, USA; (M.M.R.); (S.S.); (S.A.); (U.S.)
| | - Soudamani Singh
- Department of Clinical and Translational Sciences and Appalachian Clinical and Translational Science Institute and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, 1600 Medical Center Drive, Huntington, WV 25701, USA; (M.M.R.); (S.S.); (S.A.); (U.S.)
| | - Subha Arthur
- Department of Clinical and Translational Sciences and Appalachian Clinical and Translational Science Institute and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, 1600 Medical Center Drive, Huntington, WV 25701, USA; (M.M.R.); (S.S.); (S.A.); (U.S.)
| | - Cecilia Sierra-Bakhshi
- Department of Biomedical Sciences and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA; (C.T.); (C.S.-B.)
| | - Rebecca Russell
- Cabell Huntington Hospital Laboratory, Department of Pathology and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25701, USA; (R.R.); (K.D.)
| | - Krista Denning
- Cabell Huntington Hospital Laboratory, Department of Pathology and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25701, USA; (R.R.); (K.D.)
| | - Uma Sundaram
- Department of Clinical and Translational Sciences and Appalachian Clinical and Translational Science Institute and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, 1600 Medical Center Drive, Huntington, WV 25701, USA; (M.M.R.); (S.S.); (S.A.); (U.S.)
| | - Travis Salisbury
- Department of Biomedical Sciences and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA; (C.T.); (C.S.-B.)
- Department of Clinical and Translational Sciences and Appalachian Clinical and Translational Science Institute and Appalachian Center for Cellular Transport in Obesity Related Disorders, Joan C. Edwards School of Medicine, Marshall University, 1600 Medical Center Drive, Huntington, WV 25701, USA; (M.M.R.); (S.S.); (S.A.); (U.S.)
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15
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Gaowa N, Li W, Gelsinger S, Murphy B, Li S. Analysis of Host Jejunum Transcriptome and Associated Microbial Community Structure Variation in Young Calves with Feed-Induced Acidosis. Metabolites 2021; 11:414. [PMID: 34201826 PMCID: PMC8303401 DOI: 10.3390/metabo11070414] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/15/2021] [Accepted: 06/15/2021] [Indexed: 12/05/2022] Open
Abstract
Diet-induced acidosis imposes a health risk to young calves. In this study, we aimed to investigate the host jejunum transcriptome changes, along with its microbial community variations, using our established model of feed-induced ruminal acidosis in young calves. Eight bull calves were randomly assigned to two diet treatments beginning at birth (a starch-rich diet, Aci; a control diet, Con). Whole-transcriptome RNA sequencing was performed on the jejunum tissues collected at 17 weeks of age. Ribosomal RNA reads were used for studying microbial community structure variations in the jejunum. A total of 853 differentially expressed genes were identified (402 upregulated and 451 downregulated) between the two groups. The cell cycle and the digestion and absorption of protein in jejunal tissue were affected by acidosis. Compared to the control, genera of Campylobacter, Burkholderia, Acidaminococcus, Corynebacterium, and Olsenella significantly increased in abundance in the Aci group, while Lachnoclostridium and Ruminococcus were significantly lower in the Aci group. Expression changes in the AXL gene were associated with the abundance variations of a high number of genera in jejunum. Our study provided a snapshot of the transcriptome changes in the jejunum and its associated meta-transcriptome changes in microbial communities in young calves with feed-induced acidosis.
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Affiliation(s)
- Naren Gaowa
- College of Animal Science and Technology, China Agricultural University, No.2 Yuanmingyuan West Road, Haidian, Beijing 100193, China;
| | - Wenli Li
- Cell Wall Biology and Utilization Research Unit, US Dairy Forage Research Center, Agricultural Research Service, US Department of Agriculture, 1925 Linden Drive, Madison, WI 53706, USA;
| | - Sonia Gelsinger
- Department of Dairy Science, University of Wisconsin-Madison, Madison, WI 53706, USA;
| | - Brianna Murphy
- Cell Wall Biology and Utilization Research Unit, US Dairy Forage Research Center, Agricultural Research Service, US Department of Agriculture, 1925 Linden Drive, Madison, WI 53706, USA;
| | - Shengli Li
- College of Animal Science and Technology, China Agricultural University, No.2 Yuanmingyuan West Road, Haidian, Beijing 100193, China;
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16
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Hayashi N, Yamasaki A, Ueda S, Okazaki S, Ohno Y, Tanaka T, Endo Y, Tomioka Y, Masuko K, Masuko T, Sugiura R. Oncogenic transformation of NIH/3T3 cells by the overexpression of L-type amino acid transporter 1, a promising anti-cancer target. Oncotarget 2021; 12:1256-1270. [PMID: 34194623 PMCID: PMC8238248 DOI: 10.18632/oncotarget.27981] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 05/26/2021] [Indexed: 01/10/2023] Open
Abstract
L-type amino acid transporter 1 (LAT1)/SLC7A5 is the first identified CD98 light chain disulfide linked to the CD98 heavy chain (CD98hc/SLC3A2). LAT1 transports large neutral amino acids, including leucine, which activates mTOR, and is highly expressed in human cancers. We investigated the oncogenicity of human LAT1 introduced to NIH/3T3 cells by retrovirus infection. NIH/3T3 cell lines stably expressing human native (164C) or mutant (164S) LAT1 (naLAT1/3T3 or muLAT1/3T3, respectively) were established. We confirmed that endogenous mouse CD98hc forms a disulfide bond with exogenous human LAT1 in naLAT1/3T3, but not in muLAT1/3T3. Endogenous mouse CD98hc mRNA increased in both naNIH/3T3 and muLAT1/3T3, and a similar amount of exogenous human LAT1 protein was detected in both cell lines. Furthermore, naLAT1/3T3 and muLAT1/3T3 cell lines were evaluated for cell growth-related phenotypes (phosphorylation of ERK, cell-cycle progression) and cell malignancy-related phenotypes (anchorage-independent cell growth, tumor formation in nude mice). naLAT1/3T3 had stronger growth- and malignancy- related phenotypes than NIH/3T3 and muLAT1/3T3, suggesting the oncogenicity of native LAT1 through its interaction with CD98hc. Anti-LAT1 monoclonal antibodies significantly inhibited in vitro cell proliferation and in vivo tumor growth of naLAT1/3T3 cells in nude mice, demonstrating LAT1 to be a promising anti-cancer target.
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Affiliation(s)
- Natsumi Hayashi
- Laboratory of Molecular Pharmacogenomics, Faculty of Pharmacy, Kindai University, Higashiosaka-Shi, Osaka, Japan.,Cell Biology Laboratory, School of Pharmacy, Kindai University, Osaka, Japan.,Co-first authors.,This laboratory (April, 2000~) was closed at the end of March, 2020, after the mandatory retirement of Takashi Masuko
| | - Akitaka Yamasaki
- Cell Biology Laboratory, School of Pharmacy, Kindai University, Osaka, Japan.,Laboratory of Oncology Pharmacy Practice and Science, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai-Shi, Miyagi, Japan.,Co-first authors.,This laboratory (April, 2000~) was closed at the end of March, 2020, after the mandatory retirement of Takashi Masuko
| | - Shiho Ueda
- Cell Biology Laboratory, School of Pharmacy, Kindai University, Osaka, Japan
| | - Shogo Okazaki
- Division of Cell Fate Regulation, Research Institute for Biomedical Sciences, Tokyo University of Science, Noda-shi, Chiba, Japan
| | - Yoshiya Ohno
- Laboratory of Immunobiology, Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe-Shi, Hyogo, Japan
| | - Toshiyuki Tanaka
- Laboratory of Immunobiology, Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Kobe-Shi, Hyogo, Japan
| | - Yuichi Endo
- Natural Drug Resources, Faculty of Pharmacy, Kindai University, Osaka, Japan
| | - Yoshihisa Tomioka
- Laboratory of Oncology Pharmacy Practice and Science, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai-Shi, Miyagi, Japan
| | - Kazue Masuko
- Cell Biology Laboratory, School of Pharmacy, Kindai University, Osaka, Japan
| | - Takashi Masuko
- Cell Biology Laboratory, School of Pharmacy, Kindai University, Osaka, Japan.,Natural Drug Resources, Faculty of Pharmacy, Kindai University, Osaka, Japan
| | - Reiko Sugiura
- Laboratory of Molecular Pharmacogenomics, Faculty of Pharmacy, Kindai University, Higashiosaka-Shi, Osaka, Japan
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17
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Pellizzari G, Martinez O, Crescioli S, Page R, Di Meo A, Mele S, Chiaruttini G, Hoinka J, Batruch I, Prassas I, Grandits M, López-Abente J, Bugallo-Blanco E, Ward M, Bax HJ, French E, Cheung A, Lombardi S, Figini M, Lacy KE, Diamandis EP, Josephs DH, Spicer J, Papa S, Karagiannis SN. Immunotherapy using IgE or CAR T cells for cancers expressing the tumor antigen SLC3A2. J Immunother Cancer 2021; 9:jitc-2020-002140. [PMID: 34112739 PMCID: PMC8194339 DOI: 10.1136/jitc-2020-002140] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2021] [Indexed: 01/21/2023] Open
Abstract
Background Cancer immunotherapy with monoclonal antibodies and chimeric antigen receptor (CAR) T cell therapies can benefit from selection of new targets with high levels of tumor specificity and from early assessments of efficacy and safety to derisk potential therapies. Methods Employing mass spectrometry, bioinformatics, immuno-mass spectrometry and CRISPR/Cas9 we identified the target of the tumor-specific SF-25 antibody. We engineered IgE and CAR T cell immunotherapies derived from the SF-25 clone and evaluated potential for cancer therapy. Results We identified the target of the SF-25 clone as the tumor-associated antigen SLC3A2, a cell surface protein with key roles in cancer metabolism. We generated IgE monoclonal antibody, and CAR T cell immunotherapies each recognizing SLC3A2. In concordance with preclinical and, more recently, clinical findings with the first-in-class IgE antibody MOv18 (recognizing the tumor-associated antigen Folate Receptor alpha), SF-25 IgE potentiated Fc-mediated effector functions against cancer cells in vitro and restricted human tumor xenograft growth in mice engrafted with human effector cells. The antibody did not trigger basophil activation in cancer patient blood ex vivo, suggesting failure to induce type I hypersensitivity, and supporting safe therapeutic administration. SLC3A2-specific CAR T cells demonstrated cytotoxicity against tumor cells, stimulated interferon-γ and interleukin-2 production in vitro. In vivo SLC3A2-specific CAR T cells significantly increased overall survival and reduced growth of subcutaneous PC3-LN3-luciferase xenografts. No weight loss, manifestations of cytokine release syndrome or graft-versus-host disease, were detected. Conclusions These findings identify efficacious and potentially safe tumor-targeting of SLC3A2 with novel immune-activating antibody and genetically modified cell therapies.
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Affiliation(s)
- Giulia Pellizzari
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK
| | - Olivier Martinez
- Immunoengineering Group, King's College London, London, England, UK
| | - Silvia Crescioli
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK
| | - Robert Page
- Immunoengineering Group, King's College London, London, England, UK
| | - Ashley Di Meo
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Silvia Mele
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK
| | - Giulia Chiaruttini
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK
| | - Jan Hoinka
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Ihor Batruch
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Ioannis Prassas
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.,Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Melanie Grandits
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK
| | - Jacobo López-Abente
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK
| | | | | | - Heather J Bax
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK
| | - Elise French
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK
| | - Anthony Cheung
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK.,Breast Cancer Now Research Unit, School of Cancer and Pharmaceutical Sciences, King's College London, London, England, UK
| | - Sara Lombardi
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK.,School of Cancer and Pharmaceutical Sciences, King's College London, London, England, UK
| | - Mariangela Figini
- Biomarker Unit, Dipartimento di Ricerca Applicata e Sviluppo Tecnologico (DRAST), Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Katie E Lacy
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK
| | - Eleftherios P Diamandis
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.,Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Department of Clinical Biochemistry, University Health Network, Toronto, Ontario, Canada
| | - Debra H Josephs
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK.,Department of Medical Oncology, Guy's and St Thomas' NHS Foundation Trust, London, England, UK
| | - James Spicer
- School of Cancer and Pharmaceutical Sciences, King's College London, London, England, UK
| | - Sophie Papa
- Immunoengineering Group, King's College London, London, England, UK .,Department of Medical Oncology, Guy's and St Thomas' NHS Foundation Trust, London, England, UK
| | - Sophia N Karagiannis
- St John's Institute of Dermatology, School of Basic and Medical Biosciences, King's College London, London, England, UK .,Breast Cancer Now Research Unit, School of Cancer and Pharmaceutical Sciences, King's College London, London, England, UK
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18
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Fairweather SJ, Shah N, Brӧer S. Heteromeric Solute Carriers: Function, Structure, Pathology and Pharmacology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 21:13-127. [PMID: 33052588 DOI: 10.1007/5584_2020_584] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Solute carriers form one of three major superfamilies of membrane transporters in humans, and include uniporters, exchangers and symporters. Following several decades of molecular characterisation, multiple solute carriers that form obligatory heteromers with unrelated subunits are emerging as a distinctive principle of membrane transporter assembly. Here we comprehensively review experimentally established heteromeric solute carriers: SLC3-SLC7 amino acid exchangers, SLC16 monocarboxylate/H+ symporters and basigin/embigin, SLC4A1 (AE1) and glycophorin A exchanger, SLC51 heteromer Ost α-Ost β uniporter, and SLC6 heteromeric symporters. The review covers the history of the heteromer discovery, transporter physiology, structure, disease associations and pharmacology - all with a focus on the heteromeric assembly. The cellular locations, requirements for complex formation, and the functional role of dimerization are extensively detailed, including analysis of the first complete heteromer structures, the SLC7-SLC3 family transporters LAT1-4F2hc, b0,+AT-rBAT and the SLC6 family heteromer B0AT1-ACE2. We present a systematic analysis of the structural and functional aspects of heteromeric solute carriers and conclude with common principles of their functional roles and structural architecture.
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Affiliation(s)
- Stephen J Fairweather
- Research School of Biology, Australian National University, Canberra, ACT, Australia. .,Resarch School of Chemistry, Australian National University, Canberra, ACT, Australia.
| | - Nishank Shah
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Stefan Brӧer
- Research School of Biology, Australian National University, Canberra, ACT, Australia.
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19
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Errasti-Murugarren E, Palacín M. Heteromeric Amino Acid Transporters in Brain: from Physiology to Pathology. Neurochem Res 2021; 47:23-36. [PMID: 33606172 DOI: 10.1007/s11064-021-03261-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 01/27/2021] [Accepted: 01/30/2021] [Indexed: 12/12/2022]
Abstract
In humans, more than 50 transporters are responsible for the traffic and balance of amino acids within and between cells and tissues, and half of them have been associated with disease [1]. Covering all common amino acids, Heteromeric Amino acid Transporters (HATs) are one class of such transporters. This review first highlights structural and functional studies that solved the atomic structure of HATs and revealed molecular clues on substrate interaction. Moreover, this review focuses on HATs that have a role in the central nervous system (CNS) and that are related to neurological diseases, including: (i) LAT1/CD98hc and its role in the uptake of branched chain amino acids trough the blood brain barrier and autism. (ii) LAT2/CD98hc and its potential role in the transport of glutamine between plasma and cerebrospinal fluid. (iii) y+LAT2/CD98hc that is emerging as a key player in hepatic encephalopathy. xCT/CD98hc as a potential therapeutic target in glioblastoma, and (iv) Asc-1/CD98hc as a potential therapeutic target in pathologies with alterations in NMDA glutamate receptors.
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Affiliation(s)
- Ekaitz Errasti-Murugarren
- Institute for Research in Biomedicine. Institute of Science and Technology (BIST), 08028, Barcelona, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 08028, Barcelona, Spain.
| | - Manuel Palacín
- Institute for Research in Biomedicine. Institute of Science and Technology (BIST), 08028, Barcelona, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 08028, Barcelona, Spain. .,Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, University of Barcelona, 08028, Barcelona, Spain.
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20
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To VPTH, Masagounder K, Loewen ME. Critical transporters of methionine and methionine hydroxyl analogue supplements across the intestine: What we know so far and what can be learned to advance animal nutrition. Comp Biochem Physiol A Mol Integr Physiol 2021; 255:110908. [PMID: 33482339 DOI: 10.1016/j.cbpa.2021.110908] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/15/2020] [Accepted: 01/11/2021] [Indexed: 11/19/2022]
Abstract
DL-methionine (DL-Met) and its analogue DL-2-hydroxy-4-(methylthio) butanoic acid (DL-methionine hydroxyl analogue or DL-MHA) have been used as nutritional supplements in the diets of farmed raised animals. Knowledge of the intestinal transport mechanisms involved in these products is important for developing dietary strategies. This review provides updated information of the expression, function, and transport kinetics in the intestine of known Met-linked transporters along with putative MHA-linked transporters. As a neutral amino acid (AA), the transport of DL-Met is facilitated by multiple apical sodium-dependent/-independent high-/low-affinity transporters such as ASCT2, B0AT1 and rBAT/b0,+AT. The basolateral transport largely relies on the rate-limiting uniporter LAT4, while the presence of the basolateral antiporter y+LAT1 is probably necessary for exchanging intracellular cationic AAs and Met in the blood. In contrast, the intestinal transport kinetics of DL-MHA have been scarcely studied. DL-MHA transport is generally accepted to be mediated simply by the proton-dependent monocarboxylate transporter MCT1. However, in-depth mechanistic studies have indicated that DL-MHA transport is also achieved through apical sodium monocarboxylate transporters (SMCTs). In any case, reliance on either a proton or sodium gradient would thus require energy input for both Met and MHA transport. This expanding knowledge of the specific transporters involved now allows us to assess the effect of dietary ingredients on the expression and function of these transporters. Potentially, the resulting information could be furthered with selective breeding to reduce overall feed costs.
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Affiliation(s)
- Van Pham Thi Ha To
- Veterinary Biomedical Science, University of Saskatchewan, Saskatoon, SK, Canada
| | | | - Matthew E Loewen
- Veterinary Biomedical Science, University of Saskatchewan, Saskatoon, SK, Canada.
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21
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Shen L, Sharma D, Yu Y, Long F, Karner CM. Biphasic regulation of glutamine consumption by WNT during osteoblast differentiation. J Cell Sci 2021; 134:jcs251645. [PMID: 33262314 PMCID: PMC7823158 DOI: 10.1242/jcs.251645] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 11/19/2020] [Indexed: 01/01/2023] Open
Abstract
Osteoblasts are the principal bone-forming cells. As such, osteoblasts have enhanced demand for amino acids to sustain high rates of matrix synthesis associated with bone formation. The precise systems utilized by osteoblasts to meet these synthetic demands are not well understood. WNT signaling is known to rapidly stimulate glutamine uptake during osteoblast differentiation. Using a cell biology approach, we identified two amino acid transporters, γ(+)-LAT1 and ASCT2 (encoded by Slc7a7 and Slc1a5, respectively), as the primary transporters of glutamine in response to WNT. ASCT2 mediates the majority of glutamine uptake, whereas γ(+)-LAT1 mediates the rapid increase in glutamine uptake in response to WNT. Mechanistically, WNT signals through the canonical β-catenin (CTNNB1)-dependent pathway to rapidly induce Slc7a7 expression. Conversely, Slc1a5 expression is regulated by the transcription factor ATF4 downstream of the mTORC1 pathway. Targeting either Slc1a5 or Slc7a7 using shRNA reduced WNT-induced glutamine uptake and prevented osteoblast differentiation. Collectively, these data highlight the critical nature of glutamine transport for WNT-induced osteoblast differentiation.This article has an associated First Person interview with the joint first authors of the paper.
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Affiliation(s)
- Leyao Shen
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC 27710, USA
| | - Deepika Sharma
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC 27710, USA
| | - Yilin Yu
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC 27710, USA
| | - Fanxin Long
- Translational Research Program in Pediatric Orthopaedics, The Children's Hospital of Philadelphia, Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Courtney M Karner
- Department of Orthopaedic Surgery, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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22
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Transport of L-Arginine Related Cardiovascular Risk Markers. J Clin Med 2020; 9:jcm9123975. [PMID: 33302555 PMCID: PMC7764698 DOI: 10.3390/jcm9123975] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/30/2020] [Accepted: 12/01/2020] [Indexed: 12/15/2022] Open
Abstract
L-arginine and its derivatives, asymmetric and symmetric dimethylarginine (ADMA and SDMA) and L-homoarginine, have emerged as cardiovascular biomarkers linked to cardiovascular outcomes and various metabolic and functional pathways such as NO-mediated endothelial function. Cellular uptake and efflux of L-arginine and its derivatives are facilitated by transport proteins. In this respect the cationic amino acid transporters CAT1 and CAT2 (SLC7A1 and SLC7A2) and the system y+L amino acid transporters (SLC7A6 and SLC7A7) have been most extensively investigated, so far, but the number of transporters shown to mediate the transport of L-arginine and its derivatives is constantly increasing. In the present review we assess the growing body of evidence regarding the function, expression, and clinical relevance of these transporters and their possible relation to cardiovascular diseases.
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23
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ACE2 and gut amino acid transport. Clin Sci (Lond) 2020; 134:2823-2833. [PMID: 33140827 DOI: 10.1042/cs20200477] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 12/22/2022]
Abstract
ACE2 is a type I membrane protein with extracellular carboxypeptidase activity displaying a broad tissue distribution with highest expression levels at the brush border membrane (BBM) of small intestine enterocytes and a lower expression in stomach and colon. In small intestinal mucosa, ACE2 mRNA expression appears to increase with age and to display higher levels in patients taking ACE-inhibitors (ACE-I). There, ACE2 protein heterodimerizes with the neutral amino acid transporter Broad neutral Amino acid Transporter 1 (B0AT1) (SLC6A19) or the imino acid transporter Sodium-dependent Imino Transporter 1 (SIT1) (SLC6A20), associations that are required for the surface expression of these transport proteins. These heterodimers can form quaternary structures able to function as binding sites for SARS-CoV-2 spike glycoproteins. The heterodimerization of the carboxypeptidase ACE2 with B0AT1 is suggested to favor the direct supply of substrate amino acids to the transporter, but whether this association impacts the ability of ACE2 to mediate viral infection is not known. B0AT1 mutations cause Hartnup disorder, a condition characterized by neutral aminoaciduria and, in some cases, pellagra-like symptoms, such as photosensitive rash, diarrhea, and cerebellar ataxia. Correspondingly, the lack of ACE2 and the concurrent absence of B0AT1 expression in small intestine causes a decrease in l-tryptophan absorption, niacin deficiency, decreased intestinal antimicrobial peptide production, and increased susceptibility to inflammatory bowel disease (IBD) in mice. Thus, the abundant expression of ACE2 in small intestine and its association with amino acid transporters appears to play a crucial role for the digestion of peptides and the absorption of amino acids and, thereby, for the maintenance of structural and functional gut integrity.
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24
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The Arabidopsis L-Type Amino Acid Transporter 5 (LAT5/PUT5) Is Expressed in the Phloem and Alters Seed Nitrogen Content When Knocked Out. PLANTS 2020; 9:plants9111519. [PMID: 33182302 PMCID: PMC7695346 DOI: 10.3390/plants9111519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/28/2020] [Accepted: 11/03/2020] [Indexed: 11/25/2022]
Abstract
The Arabidopsis L-type Amino Acid Transporter-5 (LAT5; At3g19553) was recently studied for its role in developmental responses such as flowering and senescence, under an assumption that it is a polyamine uptake transporter (PUT5). The LATs in Arabidopsis have a wide range of substrates, including amino acids and polyamines. This report extensively studied the organ and tissue-specific expression of the LAT5/PUT5 and investigated its role in mediating amino acid transport. Organ-specific quantitative RT-PCR detected LAT5/PUT5 transcripts in all organs with a relatively higher abundance in the leaves. Tissue-specific expression analysis identified GUS activity in the phloem under the LAT5/PUT5 promoter. In silico analysis identified both amino acid transporter and antiporter domains conserved in the LAT5/PUT5 protein. The physiological role of the LAT5/PUT5 was studied through analyzing a mutant line, lat5-1, under various growth conditions. The mutant lat5-1 seedlings showed increased sensitivity to exogenous leucine in Murashige and Skoog growth medium. In soil, the lat5-1 showed reduced leaf growth and altered nitrogen content in the seeds. In planta radio-labelled leucine uptake studies showed increased accumulation of leucine in the lat5-1 plants compared to the wild type when treated in the dark prior to the isotopic feeding. These studies suggest that LAT5/PUT5 plays a role in mediating amino acid transport.
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25
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To VPTH, Masagounder K, Loewen ME. SLC transporters ASCT2, B 0 AT1-like, y + LAT1, and LAT4-like associate with methionine electrogenic and radio-isotope flux kinetics in rainbow trout intestine. Physiol Rep 2020; 7:e14274. [PMID: 31705630 PMCID: PMC6841986 DOI: 10.14814/phy2.14274] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 09/21/2019] [Indexed: 01/08/2023] Open
Abstract
Methionine (Met) is an important building block and metabolite for protein biosynthesis. However, the mechanism behind its absorption in the fish gut has not been elucidated. Here, we describe the fundamental properties of Met transport along trout gut at µmol/L and mmol/L concentration. Both electrogenic and unidirectional DL‐[14C]Met flux were employed to characterize Met transporters in Ussing chambers. Exploiting the differences in gene expression between diploid (2N) and triploid (3N) and intestinal segment as tools, allowed the association between gene and methionine transport. Specifically, three intestinal segments including pyloric caeca (PC), midgut (MG), and hindgut (HG) were assessed. Results at 0–150 µmol/L concentration demonstrated that the DL‐Met was most likely transported by apical transporter ASCT2 (SLC1A5) and recycled by basolateral transporter y+LAT1 (SLC7A7) due to five lines of observation: (1) lack of Na+‐independent kinetics, (2) low expression of B0AT2‐like gene, (3) Na+‐dependent, high‐affinity (Km, µmol/L ranges) kinetics in DL‐[14C]Met flux, (4) association mRNA expression with the high‐affinity kinetics and (5) electrogenic currents induced by Met. Results at 0.2–20 mmol/L concentration suggested that the DL‐Met transport is likely transported by B0AT1‐like (SLC6A19‐like) based on gene expression, Na+‐dependence and low‐affinity kinetics (Km, mmol/L ranges). Similarly, genomic and gene expression analysis suggest that the basolateral exit of methionine was primarily through LAT4‐like transporter (SLC43A2‐like). Conclusively, DL‐Met uptake in trout gut was most likely governed by Na+‐dependent apical transporters ASCT2 and B0AT1‐like and released through basolateral LAT4‐like, with some recycling through y+LAT1. A comparatively simpler model than that previously described in mammals.
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Affiliation(s)
- Van P T H To
- Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | - Matthew E Loewen
- Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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26
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Gamble LD, Purgato S, Murray J, Xiao L, Yu DMT, Hanssen KM, Giorgi FM, Carter DR, Gifford AJ, Valli E, Milazzo G, Kamili A, Mayoh C, Liu B, Eden G, Sarraf S, Allan S, Di Giacomo S, Flemming CL, Russell AJ, Cheung BB, Oberthuer A, London WB, Fischer M, Trahair TN, Fletcher JI, Marshall GM, Ziegler DS, Hogarty MD, Burns MR, Perini G, Norris MD, Haber M. Inhibition of polyamine synthesis and uptake reduces tumor progression and prolongs survival in mouse models of neuroblastoma. Sci Transl Med 2020; 11:11/477/eaau1099. [PMID: 30700572 DOI: 10.1126/scitranslmed.aau1099] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 01/08/2019] [Indexed: 12/18/2022]
Abstract
Amplification of the MYCN oncogene is associated with an aggressive phenotype and poor outcome in childhood neuroblastoma. Polyamines are highly regulated essential cations that are frequently elevated in cancer cells, and the rate-limiting enzyme in polyamine synthesis, ornithine decarboxylase 1 (ODC1), is a direct transcriptional target of MYCN. Treatment of neuroblastoma cells with the ODC1 inhibitor difluoromethylornithine (DFMO), although a promising therapeutic strategy, is only partially effective at impeding neuroblastoma cell growth due to activation of compensatory mechanisms resulting in increased polyamine uptake from the surrounding microenvironment. In this study, we identified solute carrier family 3 member 2 (SLC3A2) as the key transporter involved in polyamine uptake in neuroblastoma. Knockdown of SLC3A2 in neuroblastoma cells reduced the uptake of the radiolabeled polyamine spermidine, and DFMO treatment increased SLC3A2 protein. In addition, MYCN directly increased polyamine synthesis and promoted neuroblastoma cell proliferation by regulating SLC3A2 and other regulatory components of the polyamine pathway. Inhibiting polyamine uptake with the small-molecule drug AMXT 1501, in combination with DFMO, prevented or delayed tumor development in neuroblastoma-prone mice and extended survival in rodent models of established tumors. Our findings suggest that combining AMXT 1501 and DFMO with standard chemotherapy might be an effective strategy for treating neuroblastoma.
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Affiliation(s)
- Laura D Gamble
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia
| | - Stefania Purgato
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, 40126, Italy
| | - Jayne Murray
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia
| | - Lin Xiao
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia
| | - Denise M T Yu
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia
| | - Kimberley M Hanssen
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia
| | - Federico M Giorgi
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, 40126, Italy
| | - Daniel R Carter
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia.,School of Biomedical Engineering, University of Technology, Sydney, NSW 2007, Australia
| | - Andrew J Gifford
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia.,Department of Anatomical Pathology (SEALS), Prince of Wales Hospital, Randwick, NSW 2031, Australia
| | - Emanuele Valli
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia
| | - Giorgio Milazzo
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, 40126, Italy
| | - Alvin Kamili
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia
| | - Chelsea Mayoh
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia
| | - Bing Liu
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia
| | - Georgina Eden
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia
| | - Sara Sarraf
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia
| | - Sophie Allan
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia
| | - Simone Di Giacomo
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, 40126, Italy
| | - Claudia L Flemming
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia
| | - Amanda J Russell
- Cancer Research Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Belamy B Cheung
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia
| | - Andre Oberthuer
- Children's Hospital, Department of Pediatric Oncology and Hematology, University of Cologne, Kerpener Strasse 62, D-50924 Cologne, Germany
| | - Wendy B London
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA 02215, USA
| | - Matthias Fischer
- Children's Hospital, Department of Pediatric Oncology and Hematology, University of Cologne, Kerpener Strasse 62, D-50924 Cologne, Germany
| | - Toby N Trahair
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia.,Kids Cancer Centre, Sydney Children's Hospital, High Street, Randwick, NSW 2031, Australia
| | - Jamie I Fletcher
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia
| | - Glenn M Marshall
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia.,Kids Cancer Centre, Sydney Children's Hospital, High Street, Randwick, NSW 2031, Australia
| | - David S Ziegler
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia.,Kids Cancer Centre, Sydney Children's Hospital, High Street, Randwick, NSW 2031, Australia
| | - Michael D Hogarty
- Division of Oncology, Children's Hospital of Philadelphia, Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104-4318, USA
| | - Mark R Burns
- Aminex Therapeutics, Aminex Therapeutics Inc., Kirkland, WA 98034, USA
| | - Giovanni Perini
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, 40126, Italy
| | - Murray D Norris
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia.,University of New South Wales Centre for Childhood Cancer Research, Sydney, NSW 2052, Australia
| | - Michelle Haber
- Children's Cancer Institute, Lowy Cancer Research Centre, UNSW Australia, PO Box 81, Randwick, NSW 2031, Australia. .,School of Women's & Children's Health, UNSW Australia, Randwick, NSW 2052, Australia
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27
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Exchange-mode glutamine transport across CNS cell membranes. Neuropharmacology 2019; 161:107560. [PMID: 30853601 DOI: 10.1016/j.neuropharm.2019.03.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 02/28/2019] [Accepted: 03/02/2019] [Indexed: 12/18/2022]
Abstract
CNS cell membranes possess four transporters capable of exchanging Lglutamine (Gln) for other amino acids: the large neutral amino acid (LNAA) transporters LAT1 and LAT2, the hybrid basic amino acid (L-arginine (Arg), L-leucine (Leu)/LNAA transporter y+LAT2, and the L-alanine/L-serine/L-cysteine transporter 2 (ASCT2). LAT1/LAT2 and y+LAT2 are present in astrocytes, neurons and the blood brain barrier (BBB) - forming cerebral vascular endothelial cells (CVEC), while the location of ASCT2 in the individual cell types is a matter of debate. In the healthy brain, contribution of the exchangers to Gln shuttling from astrocytes to neurons and thus their role in controlling the conversion of Gln to the amino acid neurotransmitters l-glutamate (Glu) and γ-aminobutyric acid (GABA) and Gln flux across the BBB appears negligible as compared to the system A and system N uniporters. Insofar, except for the contribution of LAT1 to the maintenance of Gln homeostasis in the interstitial fluid (ISF), no well-defined CNS-specific function has been established for either of the three transporters in the healthy brain. The Gln-accepting amino acid exchangers appear to gain significance under conditions of excessive brain Gln load (glutaminosis). Excess Gln efflux across the BBB enhances influx into the brain of L-tryptophan (Trp). Excess of Trp is responsible for overloading the brain with neuroactive compounds: serotonin, kynurenic acid, quinolinic acid and/or oxindole, which contribute to neurotransmission imbalance accompanying hyperammonemia. In turn, alterations of y+LAT2-mediated Gln/Arg exchange and Arg uptake in astrocyte, modulate astrocytic nitric oxide synthesis and oxidative/nitrosative stress in ammonia-overexposed brain. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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28
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Ueda S, Hayashi H, Miyamoto T, Abe S, Hirai K, Matsukura K, Yagi H, Hara Y, Yoshida K, Okazaki S, Tamura M, Abe Y, Agatsuma T, Niwa S, Masuko K, Masuko T. Anti-tumor effects of mAb against L-type amino acid transporter 1 (LAT1) bound to human and monkey LAT1 with dual avidity modes. Cancer Sci 2019; 110:674-685. [PMID: 30548114 PMCID: PMC6361610 DOI: 10.1111/cas.13908] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/30/2018] [Accepted: 12/05/2018] [Indexed: 02/06/2023] Open
Abstract
l‐Type amino acid transporter 1 (LAT1) disulfide linked to CD98 heavy chain (hc) is highly expressed in most cancer cells, but weakly expressed in normal cells. In the present study, we developed novel anti‐LAT1 mAbs and showed internalization activity, inhibitory effects of amino acid uptake and cell growth and antibody‐dependent cellular cytotoxicity, as well as in vivo antitumor effects in athymic mice. Furthermore, we examined the reactivity of mAbs with LAT1 of Macaca fascicularis to evaluate possible side‐effects of antihuman LAT1 mAbs in clinical trials. Antihuman LAT1 mAbs reacted with ACHN human and MK.P3 macaca kidney‐derived cells, and this reactivity was significantly decreased by siRNAs against LAT1. Macaca LAT1 cDNA was cloned from MK.P3, and only two amino acid differences between human and macaca LAT1 were seen. RH7777 rat hepatoma and HEK293 human embryonic kidney cells expressing macaca LAT1 were established as stable transfectants, and antihuman LAT1 mAbs were equivalently reactive against transfectants expressing human or macaca LAT1. Dual (high and low) avidity modes were detected in transfectants expressing macaca LAT1, MK.P3, ACHN and HCT116 human colon cancer cells, and KA values were increased by anti‐CD98hc mAb, suggesting anti‐LAT1 mAbs detect an epitope on LAT1‐CD98hc complexes on the cell surface. Based on these results, LAT1 may be a promising anticancer target and Macaca fascicularis can be used in preclinical studies with antihuman LAT1 mAbs.
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Affiliation(s)
- Shiho Ueda
- Cell Biology LaboratorySchool of PharmacyKindai UniversityOsakaJapan
| | | | - Takako Miyamoto
- Cell Biology LaboratorySchool of PharmacyKindai UniversityOsakaJapan
| | - Shinya Abe
- Laboratory of Biological ProtectionInstitute for Viral Research, Kyoto UniversityKyotoJapan
| | - Kana Hirai
- Cell Biology LaboratorySchool of PharmacyKindai UniversityOsakaJapan
| | - Kanji Matsukura
- Cell Biology LaboratorySchool of PharmacyKindai UniversityOsakaJapan
| | - Hideki Yagi
- School of PharmacyInternational University of Health and WelfareOtawaraJapan
| | - Yuta Hara
- Cell Biology LaboratorySchool of PharmacyKindai UniversityOsakaJapan
| | - Kinji Yoshida
- Cell Biology LaboratorySchool of PharmacyKindai UniversityOsakaJapan
| | - Shogo Okazaki
- Division of Development and Aging, Research Institute for Biomedical SciencesTokyo University of ScienceChibaJapan
| | - Masakazu Tamura
- Modality Research Laboratories, Biologics DivisionDaiichi Sankyo Co., LtdTokyoJapan
| | - Yuki Abe
- Biologics & Immuno‐Oncology Laboratories, R&D DivisionDaiichi Sankyo Co., LtdTokyoJapan
| | - Toshinori Agatsuma
- Biologics & Immuno‐Oncology Laboratories, R&D DivisionDaiichi Sankyo Co., LtdTokyoJapan
| | | | - Kazue Masuko
- Cell Biology LaboratorySchool of PharmacyKindai UniversityOsakaJapan
| | - Takashi Masuko
- Cell Biology LaboratorySchool of PharmacyKindai UniversityOsakaJapan
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29
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Abstract
The small intestine mediates the absorption of amino acids after ingestion of protein and sustains the supply of amino acids to all tissues. The small intestine is an important contributor to plasma amino acid homeostasis, while amino acid transport in the large intestine is more relevant for bacterial metabolites and fluid secretion. A number of rare inherited disorders have contributed to the identification of amino acid transporters in epithelial cells of the small intestine, in particular cystinuria, lysinuric protein intolerance, Hartnup disorder, iminoglycinuria, and dicarboxylic aminoaciduria. These are most readily detected by analysis of urine amino acids, but typically also affect intestinal transport. The genes underlying these disorders have all been identified. The remaining transporters were identified through molecular cloning techniques to the extent that a comprehensive portrait of functional cooperation among transporters of intestinal epithelial cells is now available for both the basolateral and apical membranes. Mouse models of most intestinal transporters illustrate their contribution to amino acid homeostasis and systemic physiology. Intestinal amino acid transport activities can vary between species, but these can now be explained as differences of amino acid transporter distribution along the intestine. © 2019 American Physiological Society. Compr Physiol 9:343-373, 2019.
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Affiliation(s)
- Stefan Bröer
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Stephen J Fairweather
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
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30
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Pei J, Kinch LN, Grishin NV. FlyXCDB—A Resource for Drosophila Cell Surface and Secreted Proteins and Their Extracellular Domains. J Mol Biol 2018; 430:3353-3411. [DOI: 10.1016/j.jmb.2018.06.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 05/31/2018] [Accepted: 06/02/2018] [Indexed: 02/06/2023]
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31
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Vilches C, Boiadjieva-Knöpfel E, Bodoy S, Camargo S, López de Heredia M, Prat E, Ormazabal A, Artuch R, Zorzano A, Verrey F, Nunes V, Palacín M. Cooperation of Antiporter LAT2/CD98hc with Uniporter TAT1 for Renal Reabsorption of Neutral Amino Acids. J Am Soc Nephrol 2018; 29:1624-1635. [PMID: 29610403 DOI: 10.1681/asn.2017111205] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 02/24/2018] [Indexed: 01/01/2023] Open
Abstract
Background Reabsorption of amino acids (AAs) across the renal proximal tubule is crucial for intracellular and whole organism AA homeostasis. Although the luminal transport step is well understood, with several diseases caused by dysregulation of this process, the basolateral transport step is not understood. In humans, only cationic aminoaciduria due to malfunction of the basolateral transporter y+LAT1/CD98hc (SLC7A7/SLC3A2), which mediates the export of cationic AAs, has been described. Thus, the physiologic roles of basolateral transporters of neutral AAs, such as the antiporter LAT2/CD98hc (SLC7A8/SLC3A2), a heterodimer that exports most neutral AAs, and the uniporter TAT1 (SLC16A10), which exports only aromatic AAs, remain unclear. Functional cooperation between TAT1 and LAT2/CD98hc has been suggested by in vitro studies but has not been evaluated in vivoMethods To study the functional relationship of TAT1 and LAT2/CD98hc in vivo, we generated a double-knockout mouse model lacking TAT1 and LAT2, the catalytic subunit of LAT2/CD98hc (dKO LAT2-TAT1 mice).Results Compared with mice lacking only TAT1 or LAT2, dKO LAT2-TAT1 mice lost larger amounts of aromatic and other neutral AAs in their urine due to a tubular reabsorption defect. Notably, dKO mice also displayed decreased tubular reabsorption of cationic AAs and increased expression of y+LAT1/CD98hc.Conclusions The LAT2/CD98hc and TAT1 transporters functionally cooperate in vivo, and y+LAT1/CD98hc may compensate for the loss of LAT2/CD98hc and TAT1, functioning as a neutral AA exporter at the expense of some urinary loss of cationic AAs. Cooperative and compensatory mechanisms of AA transporters may explain the lack of basolateral neutral aminoacidurias in humans.
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Affiliation(s)
- Clara Vilches
- Molecular Genetics Laboratory, Genes Disease and Therapy Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain
| | - Emilia Boiadjieva-Knöpfel
- Department of Physiology.,Zurich Center for Integrative Human Physiology (ZIHP), and.,Swiss National Centre of Competence in Research (NCCR), Kidney Control of Homeostasis (Kidney.CH), University of Zurich, Zurich, Switzerland
| | - Susanna Bodoy
- Department of Biochemistry and Molecular Medicine, Biology Faculty, University of Barcelona, Barcelona, Spain.,Molecular Medicine Unit, Amino acid transporters and disease group, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Simone Camargo
- Department of Physiology.,Zurich Center for Integrative Human Physiology (ZIHP), and.,Swiss National Centre of Competence in Research (NCCR), Kidney Control of Homeostasis (Kidney.CH), University of Zurich, Zurich, Switzerland
| | - Miguel López de Heredia
- Molecular Genetics Laboratory, Genes Disease and Therapy Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and
| | - Esther Prat
- Molecular Genetics Laboratory, Genes Disease and Therapy Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and.,Genetics Section, Physiological Sciences Department, Health Sciences and Medicine Faculty, University of Barcelona, Barcelona, Spain; and
| | - Aida Ormazabal
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and.,Clinical Biochemistry Department, Institut de Recerca Sant Joan de Déu, Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Rafael Artuch
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and.,Clinical Biochemistry Department, Institut de Recerca Sant Joan de Déu, Hospital Sant Joan de Déu, Esplugues de Llobregat, Spain
| | - Antonio Zorzano
- Department of Biochemistry and Molecular Medicine, Biology Faculty, University of Barcelona, Barcelona, Spain.,Molecular Medicine Unit, Amino acid transporters and disease group, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) - CB07/08/0017, Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - François Verrey
- Department of Physiology.,Zurich Center for Integrative Human Physiology (ZIHP), and.,Swiss National Centre of Competence in Research (NCCR), Kidney Control of Homeostasis (Kidney.CH), University of Zurich, Zurich, Switzerland
| | - Virginia Nunes
- Molecular Genetics Laboratory, Genes Disease and Therapy Program, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Spain; .,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and.,Genetics Section, Physiological Sciences Department, Health Sciences and Medicine Faculty, University of Barcelona, Barcelona, Spain; and
| | - Manuel Palacín
- Department of Biochemistry and Molecular Medicine, Biology Faculty, University of Barcelona, Barcelona, Spain; .,Molecular Medicine Unit, Amino acid transporters and disease group, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER) - U730, U731, U703, and
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Jungnickel KEJ, Parker JL, Newstead S. Structural basis for amino acid transport by the CAT family of SLC7 transporters. Nat Commun 2018; 9:550. [PMID: 29416041 PMCID: PMC5803215 DOI: 10.1038/s41467-018-03066-6] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/17/2018] [Indexed: 12/12/2022] Open
Abstract
Amino acids play essential roles in cell biology as regulators of metabolic pathways. Arginine in particular is a major signalling molecule inside the cell, being a precursor for both l-ornithine and nitric oxide (NO) synthesis and a key regulator of the mTORC1 pathway. In mammals, cellular arginine availability is determined by members of the solute carrier (SLC) 7 family of cationic amino acid transporters. Whereas CAT-1 functions to supply cationic amino acids for cellular metabolism, CAT-2A and -2B are required for macrophage activation and play important roles in regulating inflammation. Here, we present the crystal structure of a close homologue of the mammalian CAT transporters that reveals how these proteins specifically recognise arginine. Our structural and functional data provide a model for cationic amino acid transport in mammalian cells and reveals mechanistic insights into proton-coupled, sodium-independent amino acid transport in the wider APC superfamily. Cationic amino acid transporters (CATs) belong to the physiologically important solute carrier (SLC) 7 family. Here, the authors present the structure of the mammalian CAT transporter homologue Geobacillus kaustophilus GkApcT, which reveals how arginine is recognized, and propose a model for proton-coupled amino acid transport.
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Affiliation(s)
| | - Joanne L Parker
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Simon Newstead
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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Characterisation of L-Type Amino Acid Transporter 1 (LAT1) Expression in Human Skeletal Muscle by Immunofluorescent Microscopy. Nutrients 2017; 10:nu10010023. [PMID: 29278358 PMCID: PMC5793251 DOI: 10.3390/nu10010023] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 11/16/2017] [Accepted: 12/13/2017] [Indexed: 12/21/2022] Open
Abstract
The branch chain amino acid leucine is a potent stimulator of protein synthesis in skeletal muscle. Leucine rapidly enters the cell via the L-Type Amino Acid Transporter 1 (LAT1); however, little is known regarding the localisation and distribution of this transporter in human skeletal muscle. Therefore, we applied immunofluorescence staining approaches to visualise LAT1 in wild type (WT) and LAT1 muscle-specific knockout (mKO) mice, in addition to basal human skeletal muscle samples. LAT1 positive staining was visually greater in WT muscles compared to mKO muscle. In human skeletal muscle, positive LAT1 staining was noted close to the sarcolemmal membrane (dystrophin positive staining), with a greater staining intensity for LAT1 observed in the sarcoplasmic regions of type II fibres (those not stained positively for myosin heavy-chain 1, Type II—25.07 ± 5.93, Type I—13.71 ± 1.98, p < 0.01), suggesting a greater abundance of this protein in these fibres. Finally, we observed association with LAT1 and endothelial nitric oxide synthase (eNOS), suggesting LAT1 association close to the microvasculature. This is the first study to visualise the distribution and localisation of LAT1 in human skeletal muscle. As such, this approach provides a validated experimental platform to study the role and regulation of LAT1 in human skeletal muscle in response to various physiological and pathophysiological models.
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Ishida A, Ashihara A, Nakashima K, Katsumata M. Expression of cationic amino acid transporters in pig skeletal muscles during postnatal development. Amino Acids 2017; 49:1805-1814. [PMID: 28803359 DOI: 10.1007/s00726-017-2478-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 08/01/2017] [Indexed: 11/24/2022]
Abstract
The cationic amino acid transporter (CAT) protein family transports lysine and arginine in cellular amino acid pools. We hypothesized that CAT expression changes in pig skeletal muscles during rapid pig postnatal development. We aimed to investigate the tissue distribution and changes in the ontogenic expression of CATs in pig skeletal muscles during postnatal development. Six piglets at 1, 12, 26, 45, and 75 days old were selected from six litters, and their longissimus dorsi (LD), biceps femoris (BF), and rhomboideus (RH) muscles, and their stomach, duodenum, jejunum, ileum, colon, liver, kidney, heart, and cerebrum were collected. CAT-1 was expressed in all the 12 tissues investigated. CAT-2 (CAT-2A isoform) expression was highest in the skeletal muscle and liver and lowest in the jejunum, ileum, kidney, and heart. CAT-3 was expressed mainly in the colon and detected in the jejunum, ileum, and cerebrum. The CAT-1 expression was higher in the skeletal muscle of day 1 pigs than in that of older pigs (P < 0.05). The CAT-2 mRNA level was lowest at day 1, but increased with postnatal development (P < 0.05). There was no significant change in CAT-1 expression among the LD, BF, and RH during postnatal development (P > 0.05); however, there was a change in CAT-2 expression. The CAT-2 expression was highest in the LD of 12-, 26-, 45-, and 75-day-old pigs, followed by the BF and RH (P < 0.05). These results suggest that CAT-1 and CAT-2 play different roles in pig skeletal muscles during postnatal development.
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Affiliation(s)
- Aiko Ishida
- Institute of Livestock and Grassland Science, NARO, Tsukuba, Ibaraki, 305-0901, Japan.
| | - Akane Ashihara
- Institute of Livestock and Grassland Science, NARO, Tsukuba, Ibaraki, 305-0901, Japan
| | - Kazuki Nakashima
- Institute of Livestock and Grassland Science, NARO, Tsukuba, Ibaraki, 305-0901, Japan
| | - Masaya Katsumata
- Institute of Livestock and Grassland Science, NARO, Tsukuba, Ibaraki, 305-0901, Japan.,School of Veterinary Science, Azabu University, Sagamihara, Kanagawa, 252-5201, Japan
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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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Abstract
Acid-base homeostasis is critical to maintenance of normal health. Renal ammonia excretion is the quantitatively predominant component of renal net acid excretion, both under basal conditions and in response to acid-base disturbances. Although titratable acid excretion also contributes to renal net acid excretion, the quantitative contribution of titratable acid excretion is less than that of ammonia under basal conditions and is only a minor component of the adaptive response to acid-base disturbances. In contrast to other urinary solutes, ammonia is produced in the kidney and then is selectively transported either into the urine or the renal vein. The proportion of ammonia that the kidney produces that is excreted in the urine varies dramatically in response to physiological stimuli, and only urinary ammonia excretion contributes to acid-base homeostasis. As a result, selective and regulated renal ammonia transport by renal epithelial cells is central to acid-base homeostasis. Both molecular forms of ammonia, NH3 and NH4+, are transported by specific proteins, and regulation of these transport processes determines the eventual fate of the ammonia produced. In this review, we discuss these issues, and then discuss in detail the specific proteins involved in renal epithelial cell ammonia transport.
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Affiliation(s)
- I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida; and Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida; and Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida
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Weiler A, Volkenhoff A, Hertenstein H, Schirmeier S. Metabolite transport across the mammalian and insect brain diffusion barriers. Neurobiol Dis 2017; 107:15-31. [PMID: 28237316 DOI: 10.1016/j.nbd.2017.02.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 01/02/2017] [Accepted: 02/20/2017] [Indexed: 12/31/2022] Open
Abstract
The nervous system in higher vertebrates is separated from the circulation by a layer of specialized endothelial cells. It protects the sensitive neurons from harmful blood-derived substances, high and fluctuating ion concentrations, xenobiotics or even pathogens. To this end, the brain endothelial cells and their interlinking tight junctions build an efficient diffusion barrier. A structurally analogous diffusion barrier exists in insects, where glial cell layers separate the hemolymph from the neural cells. Both types of diffusion barriers, of course, also prevent influx of metabolites from the circulation. Because neuronal function consumes vast amounts of energy and necessitates influx of diverse substrates and metabolites, tightly regulated transport systems must ensure a constant metabolite supply. Here, we review the current knowledge about transport systems that carry key metabolites, amino acids, lipids and carbohydrates into the vertebrate and Drosophila brain and how this transport is regulated. Blood-brain and hemolymph-brain transport functions are conserved and we can thus use a simple, genetically accessible model system to learn more about features and dynamics of metabolite transport into the brain.
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Affiliation(s)
- Astrid Weiler
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | - Anne Volkenhoff
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | - Helen Hertenstein
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | - Stefanie Schirmeier
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany.
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Taslimifar M, Oparija L, Verrey F, Kurtcuoglu V, Olgac U, Makrides V. Quantifying the relative contributions of different solute carriers to aggregate substrate transport. Sci Rep 2017; 7:40628. [PMID: 28091567 PMCID: PMC5238446 DOI: 10.1038/srep40628] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 12/07/2016] [Indexed: 02/07/2023] Open
Abstract
Determining the contributions of different transporter species to overall cellular transport is fundamental for understanding the physiological regulation of solutes. We calculated the relative activities of Solute Carrier (SLC) transporters using the Michaelis-Menten equation and global fitting to estimate the normalized maximum transport rate for each transporter (Vmax). Data input were the normalized measured uptake of the essential neutral amino acid (AA) L-leucine (Leu) from concentration-dependence assays performed using Xenopus laevis oocytes. Our methodology was verified by calculating Leu and L-phenylalanine (Phe) data in the presence of competitive substrates and/or inhibitors. Among 9 potentially expressed endogenous X. laevis oocyte Leu transporter species, activities of only the uniporters SLC43A2/LAT4 (and/or SLC43A1/LAT3) and the sodium symporter SLC6A19/B0AT1 were required to account for total uptake. Furthermore, Leu and Phe uptake by heterologously expressed human SLC6A14/ATB0,+ and SLC43A2/LAT4 was accurately calculated. This versatile systems biology approach is useful for analyses where the kinetics of each active protein species can be represented by the Hill equation. Furthermore, its applicable even in the absence of protein expression data. It could potentially be applied, for example, to quantify drug transporter activities in target cells to improve specificity.
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Affiliation(s)
- Mehdi Taslimifar
- The Interface Group, Institute of Physiology, University of Zurich, Switzerland.,Epithelial Transport Group, Institute of Physiology, University of Zurich, Switzerland
| | - Lalita Oparija
- Epithelial Transport Group, Institute of Physiology, University of Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
| | - Francois Verrey
- Epithelial Transport Group, Institute of Physiology, University of Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland.,National Center of Competence in Research, Kidney CH, Switzerland
| | - Vartan Kurtcuoglu
- The Interface Group, Institute of Physiology, University of Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland.,National Center of Competence in Research, Kidney CH, Switzerland
| | - Ufuk Olgac
- The Interface Group, Institute of Physiology, University of Zurich, Switzerland.,National Center of Competence in Research, Kidney CH, Switzerland
| | - Victoria Makrides
- Epithelial Transport Group, Institute of Physiology, University of Zurich, Switzerland
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Mastrototaro L, Sponder G, Saremi B, Aschenbach JR. Gastrointestinal methionine shuttle: Priority handling of precious goods. IUBMB Life 2016; 68:924-934. [DOI: 10.1002/iub.1571] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 09/22/2016] [Indexed: 01/05/2023]
Affiliation(s)
- Lucia Mastrototaro
- Institute of Veterinary Physiology, Department of Veterinary Medicine, Free University of Berlin; Berlin Germany
| | - Gerhard Sponder
- Institute of Veterinary Physiology, Department of Veterinary Medicine, Free University of Berlin; Berlin Germany
| | - Behnam Saremi
- Evonik Nutrition & Care GmbH; Animal Nutrition-Animal Nutrition Services; Hanau Germany
| | - Jörg R. Aschenbach
- Institute of Veterinary Physiology, Department of Veterinary Medicine, Free University of Berlin; Berlin Germany
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40
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Ghilain V, Wiame E, Fomekong E, Vincent MF, Dumitriu D, Nassogne MC. Unusual association between lysinuric protein intolerance and moyamoya vasculopathy. Eur J Paediatr Neurol 2016; 20:777-81. [PMID: 27321952 DOI: 10.1016/j.ejpn.2016.05.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 03/22/2016] [Accepted: 05/25/2016] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Lysinuric protein intolerance (LPI) is a form of inherited aminoaciduria caused by a deficiency in the cationic amino acid transport process on the basolateral membrane of enterocytes and renal tubular cells. Clinical signs include gastrointestinal symptoms, failure to thrive, hepatosplenomegaly, osteoporosis, episodes of coma, intellectual deficiency, lung and renal involvement, bone marrow abnormalities, as well as altered immune response. Moyamoya disease is a cerebrovascular disorder predisposing sufferers to stroke through progressive stenosis of the intracranial internal carotid arteries and their proximal branches. Patients with characteristic moyamoya vasculopathy who also exhibit well-recognized associated conditions, such as Down syndrome or sickle-cell disease, are diagnosed with moyamoya syndrome, whereas those with no known associated risk factors are said to suffer from moyamoya disease. CASE STUDY A 5-year-old girl exhibiting aversion to protein-rich food and splenomegaly presented with a history of recurrent ischemic strokes. Cerebral angiography confirmed moyamoya vasculopathy. Metabolic investigation revealed abnormalities characteristic of LPI. This diagnosis was confirmed by the detection of a mutation within the SLC7A7 gene upon molecular investigation. CONCLUSION To the best of our knowledge, this is the first reported case of an association between moyamoya vasculopathy and LPI. While the question of association or coincidence cannot yet be answered, several pathophysiological consequences of LPI can be defined as separate, such as links between the impact of low arginine levels on the function of vascular endothelium and brain nitric oxide metabolism, as well as hemophagocytic syndrome associated with the risk of vasculitis, thus accounting for the development of moyamoya vasculopathy.
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Affiliation(s)
- Valérie Ghilain
- Université Catholique de Louvain and Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Elsa Wiame
- Université Catholique de Louvain and Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Edward Fomekong
- Université Catholique de Louvain and Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | | | - Dana Dumitriu
- Université Catholique de Louvain and Cliniques Universitaires Saint-Luc, Brussels, Belgium
| | - Marie-Cécile Nassogne
- Université Catholique de Louvain and Cliniques Universitaires Saint-Luc, Brussels, Belgium.
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41
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Heteromeric amino acid transporters. In search of the molecular bases of transport cycle mechanisms1. Biochem Soc Trans 2016; 44:745-52. [DOI: 10.1042/bst20150294] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Indexed: 01/18/2023]
Abstract
Heteromeric amino acid transporters (HATs) are relevant targets for structural studies. On the one hand, HATs are involved in inherited and acquired human pathologies. On the other hand, these molecules are the only known examples of solute transporters composed of two subunits (heavy and light) linked by a disulfide bridge. Unfortunately, structural knowledge of HATs is scarce and limited to the atomic structure of the ectodomain of a heavy subunit (human 4F2hc-ED) and distant prokaryotic homologues of the light subunits that share a LeuT-fold. Recent data on human 4F2hc/LAT2 at nanometer resolution revealed 4F2hc-ED positioned on top of the external loops of the light subunit LAT2. Improved resolution of the structure of HATs, combined with conformational studies, is essential to establish the structural bases for light subunit recognition and to evaluate the functional relevance of heavy and light subunit interactions for the amino acid transport cycle.
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42
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Morales A, Buenabad L, Castillo G, Vázquez L, Espinoza S, Htoo JK, Cervantes M. Dietary levels of protein and free amino acids affect pancreatic proteases activities, amino acids transporters expression and serum amino acid concentrations in starter pigs. J Anim Physiol Anim Nutr (Berl) 2016; 101:723-732. [PMID: 27121753 DOI: 10.1111/jpn.12515] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 03/12/2016] [Indexed: 12/17/2022]
Abstract
The dietary contents of crude protein and free amino acids (AA) may affect the protein digestion and AA absorption in pigs. Trypsin and chymotrypsin activities, AA serum concentrations and expression of AA transporters in the small intestine of pigs fed a low protein, AA-supplemented (19.2%, LPAA) or a high protein (28.1%, HP), wheat-soybean meal diet were measured in two 14-d trials. The LPAA diet contained free L-Lys, L-Thr, DL-Met, L-Leu, L-Ile, L-Val, L-His, L-Trp and L-Phe. All pigs were fed the same amount of feed (890 and 800 g/d for trial 1 and 2 respectively). In trial 1, samples of mucosa (duodenum, jejunum and ileum) and digesta (duodenum and jejunum) were collected from 14 pigs (17.2 ± 0.4 kg); in trial 2, blood samples were collected from 12 pigs (12.7 ± 0.3 kg). The trypsin and chymotrypsin activities in both intestinal segments were higher in pigs fed the HP diet (p < 0.01). Trypsin activity was higher in jejunum than in duodenum regardless the dietary treatment (p < 0.05). Pigs fed the LPAA diet expressed more b0,+ AT in duodenum, B0 AT1 in ileum (p < 0.05), and tended to express more y+ LAT1 in duodenum (p = 0.10). In pigs fed the LPAA diet, the expression of b0,+ AT was higher in duodenum than in jejunum and ileum (p < 0.01), but no difference was observed in pigs fed the HP diet. Ileum had the lowest b0,+ AT expression regardless the diet. The serum concentrations of Lys, Thr and Met were higher in LPAA pigs while serum Arg was higher in HP pigs (p < 0.05). Serum concentrations of AA appear to reflect the AA absorption. In conclusion, these data indicate that the dietary protein contents affect the extent of protein digestion and that supplemental free AA may influence the intestinal site of AA release and absorption, which may impact their availability for growth of young pigs.
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Affiliation(s)
- A Morales
- Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Mexicali, México
| | - L Buenabad
- Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Mexicali, México
| | - G Castillo
- Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Mexicali, México
| | - L Vázquez
- Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Mexicali, México
| | - S Espinoza
- Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Mexicali, México
| | - J K Htoo
- Evonik Industries AG, Nutrition Research, Hanau-Wolfgang, Germany
| | - M Cervantes
- Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Mexicali, México
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Novel cystine transporter in renal proximal tubule identified as a missing partner of cystinuria-related plasma membrane protein rBAT/SLC3A1. Proc Natl Acad Sci U S A 2016; 113:775-80. [PMID: 26739563 DOI: 10.1073/pnas.1519959113] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heterodimeric amino acid transporters play crucial roles in epithelial transport, as well as in cellular nutrition. Among them, the heterodimer of a membrane protein b(0,+)AT/SLC7A9 and its auxiliary subunit rBAT/SLC3A1 is responsible for cystine reabsorption in renal proximal tubules. The mutations in either subunit cause cystinuria, an inherited amino aciduria with impaired renal reabsorption of cystine and dibasic amino acids. However, an unsolved paradox is that rBAT is highly expressed in the S3 segment, the late proximal tubules, whereas b(0,+)AT expression is highest in the S1 segment, the early proximal tubules, so that the presence of an unknown partner of rBAT in the S3 segment has been proposed. In this study, by means of coimmunoprecipitation followed by mass spectrometry, we have found that a membrane protein AGT1/SLC7A13 is the second partner of rBAT. AGT1 is localized in the apical membrane of the S3 segment, where it forms a heterodimer with rBAT. Depletion of rBAT in mice eliminates the expression of AGT1 in the renal apical membrane. We have reconstituted the purified AGT1-rBAT heterodimer into proteoliposomes and showed that AGT1 transports cystine, aspartate, and glutamate. In the apical membrane of the S3 segment, AGT1 is suggested to locate itself in close proximity to sodium-dependent acidic amino acid transporter EAAC1 for efficient functional coupling. EAAC1 is proposed to take up aspartate and glutamate released into luminal fluid by AGT1 due to its countertransport so that preventing the urinary loss of aspartate and glutamate. Taken all together, AGT1 is the long-postulated second cystine transporter in the S3 segment of proximal tubules and a possible candidate to be involved in isolated cystinuria.
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Cobbold SA, Llinás M, Kirk K. Sequestration and metabolism of host cell arginine by the intraerythrocytic malaria parasite Plasmodium falciparum. Cell Microbiol 2016; 18:820-30. [PMID: 26633083 DOI: 10.1111/cmi.12552] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/14/2015] [Accepted: 11/26/2015] [Indexed: 11/26/2022]
Abstract
Human erythrocytes have an active nitric oxide synthase, which converts arginine into citrulline and nitric oxide (NO). NO serves several important functions, including the maintenance of normal erythrocyte deformability, thereby ensuring efficient passage of the red blood cell through narrow microcapillaries. Here, we show that following invasion by the malaria parasite Plasmodium falciparum the arginine pool in the host erythrocyte compartment is sequestered and metabolized by the parasite. Arginine from the extracellular medium enters the infected cell via endogenous host cell transporters and is taken up by the intracellular parasite by a high-affinity cationic amino acid transporter at the parasite surface. Within the parasite arginine is metabolized into citrulline and ornithine. The uptake and metabolism of arginine by the parasite deprive the erythrocyte of the substrate required for NO production and may contribute to the decreased deformability of infected erythrocytes.
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Affiliation(s)
- Simon A Cobbold
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, 08544, USA.,Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Manuel Llinás
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, 08544, USA.,Department of Molecular Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Kiaran Kirk
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
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The Glutamine Transporters and Their Role in the Glutamate/GABA-Glutamine Cycle. ADVANCES IN NEUROBIOLOGY 2016; 13:223-257. [PMID: 27885631 DOI: 10.1007/978-3-319-45096-4_8] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Glutamine is a key amino acid in the CNS, playing an important role in the glutamate/GABA-glutamine cycle (GGC). In the GGC, glutamine is transferred from astrocytes to neurons, where it will replenish the inhibitory and excitatory neurotransmitter pools. Different transporters participate in this neural communication, i.e., the transporters responsible for glutamine efflux from astrocytes and influx into the neurons, such as the members of the SNAT, LAT, y+LAT, and ASC families of transporters. The SNAT family consists of the transporter isoforms SNAT3 and SNAT5 that are related to efflux from the astrocytic compartment, and SNAT1 and SNAT2 that are associated with glutamine uptake into the neuronal compartment. The isoforms SNAT7 and SNAT8 do not have their role completely understood, but they likely also participate in the GGC. The isoforms LAT2 and y+LAT2 facilitate the exchange of neutral amino acids and cationic amino acids (y+LAT2 isoform) and have been associated with glutamine efflux from astrocytes. ASCT2 is a Na+-dependent antiporter, the participation of which in the GGC also remains to be better characterized. All these isoforms are tightly regulated by transcriptional and translational mechanisms, which are induced by several determinants such as amino acid deprivation, hormones, pH, and the activity of different signaling pathways. Dysfunctional glutamine transporter activity has been associated with the pathophysiological mechanisms of certain neurologic diseases, such as Hepatic Encephalopathy and Manganism. However, there might also be other neuropathological conditions associated with an altered GGC, in which glutamine transporters are dysfunctional. Hence, it appears to be of critical importance that the physiological and pathological aspects of glutamine transporters are thoroughly investigated.
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Morales A, Buenabad L, Castillo G, Arce N, Araiza BA, Htoo JK, Cervantes M. Low-protein amino acid-supplemented diets for growing pigs: effect on expression of amino acid transporters, serum concentration, performance, and carcass composition. J Anim Sci 2015; 93:2154-64. [PMID: 26020311 DOI: 10.2527/jas.2014-8834] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Pigs fed protein-bound AA appear to have a higher abundance of AA transporters for their absorption in the jejunum compared with the duodenum. However, there is limited data about the effect of dietary free AA, readily available in the duodenum, on the duodenal abundance of AA transporters and its impact on pig performance. Forty-eight pigs (24.3 kg initial BW) distributed in 4 treatments were used to evaluate the effect of the CP level and form (free vs. protein bound) in which AA are added to diets on the expression of AA transporters in the 3 small intestine segments, serum concentration of AA, and performance. Dietary treatments based on wheat and soybean meal (SBM) were 1) low-CP (14%) diet supplemented with L-Lys, L-Thr, DL-Met, L-Leu, L-Ile, L-Val, L-His, L-Trp, and L-Phe (LPAA); 2) as in the LPAA but with added L-Gly as a N source (LPAA+N); 3) intermediate CP content (16%) supplemented with L-Lys HCl, L-Thr, and DL-Met (MPAA); and 4) high-CP (22%) diet (HP) without free AA. At the end of the experiment, 8 pigs from LPAA and HP were sacrificed to collect intestinal mucosa and blood samples and to dissect the carcasses. There were no differences in ADG, ADFI, G:F, and weights of carcass components and some visceral organs between treatments. Weights of the large intestine and kidney were higher in HP pigs (P < 0.01). Expression of b(0,+) in the duodenum was higher in pigs fed the LPAA compared with the HP diet (P= 0.036) but there was no difference in the jejunum and ileum. In the ileum, y+ L expression tended to be higher in pigs fed the LPAA diet (P = 0.098). Expression of b(0,+) in LPAA pigs did not differ between the duodenum and the jejunum, but in HP pigs, the expression of all AA transporters was higher in the jejunum than in the duodenum or ileum (P < 0.05). The serum concentration of Arg, His, Ile, Leu, Phe, and Val was higher but serum Lys and Met were lower in pigs fed the HP diet (P < 0.05). These results indicate that LPAA can substitute up to 8 percentage units of protein in HP wheat-SBM diets without affecting pig performance; nonessential N does not seem to be limiting in very low-protein wheat-SBM diets for growing pigs. Also, the inclusion of free AA in the diet appears to affect their serum concentration and the expression of the AA transporter b0,+ in the duodenum of pigs.
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Pochini L, Scalise M, Galluccio M, Indiveri C. Membrane transporters for the special amino acid glutamine: structure/function relationships and relevance to human health. Front Chem 2014; 2:61. [PMID: 25157349 PMCID: PMC4127817 DOI: 10.3389/fchem.2014.00061] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 07/16/2014] [Indexed: 12/26/2022] Open
Abstract
Glutamine together with glucose is essential for body's homeostasis. It is the most abundant amino acid and is involved in many biosynthetic, regulatory and energy production processes. Several membrane transporters which differ in transport modes, ensure glutamine homeostasis by coordinating its absorption, reabsorption and delivery to tissues. These transporters belong to different protein families, are redundant and ubiquitous. Their classification, originally based on functional properties, has recently been associated with the SLC nomenclature. Function of glutamine transporters is studied in cells over-expressing the transporters or, more recently in proteoliposomes harboring the proteins extracted from animal tissues or over-expressed in microorganisms. The role of the glutamine transporters is linked to their transport modes and coupling with Na+ and H+. Most transporters share specificity for other neutral or cationic amino acids. Na+-dependent co-transporters efficiently accumulate glutamine while antiporters regulate the pools of glutamine and other amino acids. The most acknowledged glutamine transporters belong to the SLC1, 6, 7, and 38 families. The members involved in the homeostasis are the co-transporters B0AT1 and the SNAT members 1, 2, 3, 5, and 7; the antiporters ASCT2, LAT1 and 2. The last two are associated to the ancillary CD98 protein. Some information on regulation of the glutamine transporters exist, which, however, need to be deepened. No information at all is available on structures, besides some homology models obtained using similar bacterial transporters as templates. Some models of rat and human glutamine transporters highlight very similar structures between the orthologs. Moreover the presence of glycosylation and/or phosphorylation sites located at the extracellular or intracellular faces has been predicted. ASCT2 and LAT1 are over-expressed in several cancers, thus representing potential targets for pharmacological intervention.
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Affiliation(s)
- Lorena Pochini
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
| | - Mariafrancesca Scalise
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
| | - Michele Galluccio
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
| | - Cesare Indiveri
- Department DiBEST (Biologia, Ecologia, Scienze della Terra) Unit of Biochemistry and Molecular Biotechnology, University of Calabria Arcavacata di Rende, Italy
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Corbett HE, Dubé CD, Slow S, Lever M, Trasler JM, Baltz JM. Uptake of Betaine into Mouse Cumulus-Oocyte Complexes via the SLC7A6 Isoform of y+L Transporter1. Biol Reprod 2014; 90:81. [DOI: 10.1095/biolreprod.113.116939] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Yang J, Tan Q, Zhu W, Chen C, Liang X, Pan L. Cloning and molecular characterization of cationic amino acid transporter y⁺LAT1 in grass carp (Ctenopharyngodon idellus). FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:93-104. [PMID: 23817987 DOI: 10.1007/s10695-013-9827-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 06/18/2013] [Indexed: 06/02/2023]
Abstract
The solute carrier family 7A, member 7 gene encodes the light chain- y⁺L amino acid transporter-1 (y⁺LAT1) of the heterodimeric carrier responsible for cationic amino acid (CAA) transport across the basolateral membranes of epithelial cells in intestine and kidney. Rising attention has been given to y⁺LAT1 involved in CAA metabolic pathways and growth control. The molecular characterization and function analysis of y⁺LAT1 in grass carp (Ctenopharyngodon idellus) is currently unknown. In the present study, full-length cDNA (2,688 bp), which encodes y⁺LAT1 and contains a 5'-untranslated region (319 bp), an open reading frame (1,506 bp) and a 3'-untranslated region (863 bp), has been cloned from grass carp. Amino acid sequence of grass carp y⁺LAT1 contains 11 transmembrane domains and shows 95 %, 80 % and 75 % sequence similarity to zebra fish, amphibian and mammalian y⁺LAT1, respectively. The tissue distribution and expression regulation by fasting of y⁺LAT1 mRNA were analyzed using real-time PCR. Our results showed that y⁺LAT1 mRNA was highly expressed in midgut, foregut and spleen while weakly expressed in hindgut, kidney, gill, brain, heart, liver and muscle. Nutritional status significantly influenced y⁺LAT1 mRNA expression in fish tissues, such as down-regulation of y⁺LAT1 mRNA expression after fasting (14 days).
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Affiliation(s)
- Jixuan Yang
- Fisheries College, Huazhong Agricultural University, Wuhan, 430070, China
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