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Reifenberg P, Zimmer A. Branched-chain amino acids: physico-chemical properties, industrial synthesis and role in signaling, metabolism and energy production. Amino Acids 2024; 56:51. [PMID: 39198298 PMCID: PMC11358235 DOI: 10.1007/s00726-024-03417-2] [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: 06/13/2024] [Accepted: 08/20/2024] [Indexed: 09/01/2024]
Abstract
Branched-chain amino acids (BCAAs)-leucine (Leu), isoleucine (Ile), and valine (Val)-are essential nutrients with significant roles in protein synthesis, metabolic regulation, and energy production. This review paper offers a detailed examination of the physico-chemical properties of BCAAs, their industrial synthesis, and their critical functions in various biological processes. The unique isomerism of BCAAs is presented, focusing on analytical challenges in their separation and quantification as well as their solubility characteristics, which are crucial for formulation and purification applications. The industrial synthesis of BCAAs, particularly using bacterial strains like Corynebacterium glutamicum, is explored, alongside methods such as genetic engineering aimed at enhancing production, detailing the enzymatic processes and specific precursors. The dietary uptake, distribution, and catabolism of BCAAs are reviewed as fundamental components of their physiological functions. Ultimately, their multifaceted impact on signaling pathways, immune function, and disease progression is discussed, providing insights into their profound influence on muscle protein synthesis and metabolic health. This comprehensive analysis serves as a resource for understanding both the basic and complex roles of BCAAs in biological systems and their industrial application.
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Affiliation(s)
- Philipp Reifenberg
- Merck Life Science KGaA, Upstream R&D, Frankfurter Strasse 250, 64293, Darmstadt, Germany
- Institute for Organic Chemistry and Biochemistry, Technische Universität Darmstadt, Alarich‑Weiss‑Strasse 4, 64287, Darmstadt, Germany
| | - Aline Zimmer
- Merck Life Science KGaA, Upstream R&D, Frankfurter Strasse 250, 64293, Darmstadt, Germany.
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Bröer A, Hu Z, Kukułowicz J, Yadav A, Zhang T, Dai L, Bajda M, Yan R, Bröer S. Cryo-EM structure of ACE2-SIT1 in complex with tiagabine. J Biol Chem 2024; 300:107687. [PMID: 39159813 DOI: 10.1016/j.jbc.2024.107687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 08/03/2024] [Accepted: 08/07/2024] [Indexed: 08/21/2024] Open
Abstract
The pharmacology of amino acid transporters in the SLC6 family is poorly developed compared to that of the neurotransmitter transporters. To identify new inhibitors of the proline transporter SIT1 (SLC6A20), its expression in Xenopus laevis oocytes was optimized. Trafficking of SIT1 was augmented by co-expression of angiotensin-converting enzyme 2 (ACE2) in oocytes but there was no strict requirement for co-expression of ACE2. A pharmacophore-guided screen identified tiagabine as a potent non-competitive inhibitor of SIT1. To understand its binding mode, we determined the cryo-electron microscopy (cryo-EM) structure of ACE2-SIT1 bound with tiagabine. The inhibitor binds close to the orthosteric proline binding site, but due to its size extends into the cytosolic vestibule. This causes the transporter to adopt an inward-open conformation, in which the intracellular gate is blocked. This study provides the first structural insight into inhibition of SIT1 and generates tools for a better understanding of the ACE2-SIT1 complex. These findings may have significance for SARS-CoV-2 binding to its receptor ACE2 in human lung alveolar cells where SIT1 and ACE2 are functionally expressed.
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Affiliation(s)
- Angelika Bröer
- Research School of Biology, Australian National University, Canberra, Australia
| | - Ziwei Hu
- Department of Biochemistry, Key University Laboratory of Metabolism and Health of Guangdong, School of Medicine, Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Jędrzej Kukułowicz
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Cracow, Poland
| | - Aditya Yadav
- Research School of Biology, Australian National University, Canberra, Australia
| | - Ting Zhang
- Department of Biochemistry, Key University Laboratory of Metabolism and Health of Guangdong, School of Medicine, Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Lu Dai
- Department of Biochemistry, Key University Laboratory of Metabolism and Health of Guangdong, School of Medicine, Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Marek Bajda
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Cracow, Poland
| | - Renhong Yan
- Department of Biochemistry, Key University Laboratory of Metabolism and Health of Guangdong, School of Medicine, Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, Guangdong, China.
| | - Stefan Bröer
- Research School of Biology, Australian National University, Canberra, Australia.
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Kano Y, Yamaguchi S, Mise K, Kawakita C, Onishi Y, Kurooka N, Sugawara R, Albuayjan HHH, Nakatsuka A, Eguchi J, Wada J. Inhibition of Amino Acids Influx into Proximal Tubular Cells Improves Lysosome Function in Diabetes. KIDNEY360 2024; 5:182-194. [PMID: 38062578 PMCID: PMC10914197 DOI: 10.34067/kid.0000000000000333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 11/29/2023] [Indexed: 03/01/2024]
Abstract
Key Points Collectrin serves as a chaperone for the trafficking of neutral amino acid (AA) transporters in the apical membranes of proximal tubular cells (PTCs). Cltrn knockout reduced AAs influx into PTCs, inactivated mTOR, activated transcription factor EB, improved lysosome function, and ameliorated vacuolar formation of PTCs in diabetic mice treated with streptozotocin and high-fat diet. The inhibition of neutral AA transporter, such as B0AT1 (SLC6A19), and transcription factor EB activator is a new therapeutic strategy against diabetic kidney disease. Background Inhibition of glucose influx into proximal tubular cells (PTCs) by sodium–glucose cotransporter 2 inhibitors revealed prominent therapeutic effects on diabetic kidney disease. Collectrin (CLTRN) serves as a chaperone for the trafficking of neutral amino acid (AA) transporters in the apical membranes of PTCs. We investigated the beneficial effects of reduced influx of AAs into PTCs in diabetes and obesity model of Cltrn−/y mice. Methods Cltrn+/y and Cltrn−/y mice at age 5 weeks were assigned to standard diet and streptozotocin and high-fat diet (STZ-HFD)–treated groups. Results At age 22–23 weeks, body weight and HbA1c levels significantly increased in STZ-HFD-Cltrn+/y compared with standard diet-Cltrn+/y; however, they were not altered in STZ-HFD-Cltrn−/y compared with STZ-HFD-Cltrn+/y. At age 20 weeks, urinary albumin creatinine ratio was significantly reduced in STZ-HFD-Cltrn−/y compared with STZ-HFD-Cltrn+/y. Under the treatments with STZ and HFD, the Cltrn gene deficiency caused significant increase in urinary concentration of AAs such as Gln, His, Gly, Thr, Tyr, Val, Trp, Phe, Ile, Leu, and Pro. In PTCs in STZ-HFD-Cltrn+/y, the enlarged lysosomes with diameter of 10 μ m or more were associated with reduced autolysosomes, and the formation of giant lysosomes was prominently suppressed in STZ-HFD-Cltrn−/y. Phospho-mTOR and inactive form of phospho-transcription factor EB were reduced in STZ-HFD-Cltrn−/y compared with STZ-HFD-Cltrn+/y. Conclusions The reduction of AAs influx into PTCs inactivated mTOR, activated transcription factor EB, improved lysosome function, and ameliorated vacuolar formation of PTCs in STZ-HFD-Cltrn−/y mice.
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Affiliation(s)
- Yuzuki Kano
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
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Wu S, Li C, Li Y, Liu J, Rong C, Pei H, Li X, Zeng X, Mao W. SLC2A9 rs16890979 reduces uric acid absorption by kidney organoids. Front Cell Dev Biol 2024; 11:1268226. [PMID: 38269090 PMCID: PMC10806012 DOI: 10.3389/fcell.2023.1268226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 12/14/2023] [Indexed: 01/26/2024] Open
Abstract
Introduction: The excretion and absorption of uric acid (UA) by the kidneys helps regulate serum UA levels. GLUT9, encoded by SLC2A9, is mainly expressed in the renal tubules responsible for UA absorption. SLC2A9 polymorphisms are associated with different serum UA levels. However, the lack of proper in vitro models has stalled research on the mechanisms of single nucleotide polymorphisms (SNPs) that affect UA metabolism in human urate transporters. Methods: In this study, we constructed a gene-edited human embryonic stem cells-9 (ESC-H9) derived kidney organoid bearing rs16890979, an SLC2A9 missense mutation with undetermined associations with hyperuricemia or hypouricemia. Kidney organoids derived from ESC-H9 with genetical overexpression (OE) and low expression (shRNA) of SLC2A9 to serve as controls to study the function of SLC2A9. The function of rs16890979 on UA metabolism was evaluated after placing the organoids to urate-containing medium and following histopathological analysis. Results: The kidney organoids with heterozygous or homozygous rs16890979 mutations showed normal SLC2A9 expression levels and histological distribution, phenotypically similar to the wild-type controls. However, reduced absorption of UA by the kidney organoids with rs16890979 mutants was observed. This finding together with the observation that UA absorption is increased in organoids with SLC2A9 overexpression and decreased in those with SLC2A9 knockdown, suggest that GLUT9 is responsible for UA absorption, and the rs16890979 SNP may compromise this functionality. Moreover, epithelial-mesenchymal transition (EMT) was detected in organoids after UA treatment, especially in the kidney organoid carrying GLUT9OE, suggesting the cytobiological mechanism explaining the pathological features in hyperuricosuria-related renal injury. Discussion: This study showing the transitional value of kidney organoid modeling the function of SNPs on UA metabolism. With a defined genetic background and a confirmed UA absorption function should be useful for studies on renal histological, cellular, and molecular mechanisms with this organoid model.
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Affiliation(s)
- Shouhai Wu
- State Key Laboratory of Dampness Syndrome of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
- Department of Nephrology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Chuang Li
- State Key Laboratory of Dampness Syndrome of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
- Department of Nephrology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
- Guangdong Provincial Key Laboratory of Chinese Medicine for Prevention and Treatment of Refractory Chronic Diseases, Guangzhou, China
| | - Yizhen Li
- State Key Laboratory of Dampness Syndrome of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
- The Second Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Junyi Liu
- State Key Laboratory of Dampness Syndrome of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
- The Second Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Cuiping Rong
- The Second Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Hongfei Pei
- State Key Laboratory of Dampness Syndrome of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
- Department of Nephrology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Xiong Li
- State Key Laboratory of Dampness Syndrome of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Xiang Zeng
- State Key Laboratory of Dampness Syndrome of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
- Lab of Stem Cell Biology and Innovative Research of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine/Guangdong Academy of Chinese Medicine, Guangzhou, China
- National Institute for Stem Cell Clinical Research, Guangdong Provincial Hospital of Chinese Medicine/The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wei Mao
- State Key Laboratory of Dampness Syndrome of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
- Department of Nephrology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
- Guangdong Provincial Key Laboratory of Chinese Medicine for Prevention and Treatment of Refractory Chronic Diseases, Guangzhou, China
- The Second Clinical Medical College, Guangzhou University of Chinese Medicine, Guangzhou, China
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Kukułowicz J, Pietrzak-Lichwa K, Klimończyk K, Idlin N, Bajda M. The SLC6A15-SLC6A20 Neutral Amino Acid Transporter Subfamily: Functions, Diseases, and Their Therapeutic Relevance. Pharmacol Rev 2023; 76:142-193. [PMID: 37940347 DOI: 10.1124/pharmrev.123.000886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 09/07/2023] [Accepted: 11/02/2023] [Indexed: 11/10/2023] Open
Abstract
The neutral amino acid transporter subfamily that consists of six members, consecutively SLC6A15-SLC620, also called orphan transporters, represents membrane, sodium-dependent symporter proteins that belong to the family of solute carrier 6 (SLC6). Primarily, they mediate the transport of neutral amino acids from the extracellular milieu toward cell or storage vesicles utilizing an electric membrane potential as the driving force. Orphan transporters are widely distributed throughout the body, covering many systems; for instance, the central nervous, renal, or intestinal system, supplying cells into molecules used in biochemical, signaling, and building pathways afterward. They are responsible for intestinal absorption and renal reabsorption of amino acids. In the central nervous system, orphan transporters constitute a significant medium for the provision of neurotransmitter precursors. Diseases related with aforementioned transporters highlight their significance; SLC6A19 mutations are associated with metabolic Hartnup disorder, whereas altered expression of SLC6A15 has been associated with a depression/stress-related disorders. Mutations of SLC6A18-SLCA20 cause iminoglycinuria and/or hyperglycinuria. SLC6A18-SLC6A20 to reach the cellular membrane require an ancillary unit ACE2 that is a molecular target for the spike protein of the SARS-CoV-2 virus. SLC6A19 has been proposed as a molecular target for the treatment of metabolic disorders resembling gastric surgery bypass. Inhibition of SLC6A15 appears to have a promising outcome in the treatment of psychiatric disorders. SLC6A19 and SLC6A20 have been suggested as potential targets in the treatment of COVID-19. In this review, we gathered recent advances on orphan transporters, their structure, functions, related disorders, and diseases, and in particular their relevance as therapeutic targets. SIGNIFICANCE STATEMENT: The following review systematizes current knowledge about the SLC6A15-SLCA20 neutral amino acid transporter subfamily and their therapeutic relevance in the treatment of different diseases.
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Affiliation(s)
- Jędrzej Kukułowicz
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Krzysztof Pietrzak-Lichwa
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Klaudia Klimończyk
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Nathalie Idlin
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Marek Bajda
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
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Bhatt M, Di Iacovo A, Romanazzi T, Roseti C, Cinquetti R, Bossi E. The "www" of Xenopus laevis Oocytes: The Why, When, What of Xenopus laevis Oocytes in Membrane Transporters Research. MEMBRANES 2022; 12:membranes12100927. [PMID: 36295686 PMCID: PMC9610376 DOI: 10.3390/membranes12100927] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 05/16/2023]
Abstract
After 50 years, the heterologous expression of proteins in Xenopus laevis oocytes is still essential in many research fields. New approaches and revised protocols, but also classical methods, such as the two-electrode voltage clamp, are applied in studying membrane transporters. New and old methods for investigating the activity and the expression of Solute Carriers (SLC) are reviewed, and the kinds of experiment that are still useful to perform with this kind of cell are reported. Xenopus laevis oocytes at the full-grown stage have a highly efficient biosynthetic apparatus that correctly targets functional proteins at the defined compartment. This small protein factory can produce, fold, and localize almost any kind of wild-type or recombinant protein; some tricks are required to obtain high expression and to verify the functionality. The methodologies examined here are mainly related to research in the field of membrane transporters. This work is certainly not exhaustive; it has been carried out to be helpful to researchers who want to quickly find suggestions and detailed indications when investigating the functionality and expression of the different members of the solute carrier families.
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Affiliation(s)
- Manan Bhatt
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Experimental and Translational Medicine, University of Insubria, Via Ottorino Rossi 9, 21100 Varese, Italy
| | - Angela Di Iacovo
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Experimental and Translational Medicine, University of Insubria, Via Ottorino Rossi 9, 21100 Varese, Italy
| | - Tiziana Romanazzi
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Experimental and Translational Medicine, University of Insubria, Via Ottorino Rossi 9, 21100 Varese, Italy
| | - Cristina Roseti
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Centre for Neuroscience—Via Manara 7, University of Insubria, 21052 Busto Arsizio, Italy
| | - Raffaella Cinquetti
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
| | - Elena Bossi
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, Via Dunant 3, 21100 Varese, Italy
- Centre for Neuroscience—Via Manara 7, University of Insubria, 21052 Busto Arsizio, Italy
- Correspondence:
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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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Xu B, Li G, Guo J, Ikezoe T, Kasirajan K, Zhao S, Dalman RL. Angiotensin-converting enzyme 2, coronavirus disease 2019, and abdominal aortic aneurysms. J Vasc Surg 2021; 74:1740-1751. [PMID: 33600934 PMCID: PMC7944865 DOI: 10.1016/j.jvs.2021.01.051] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 01/08/2021] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the etiologic agent of the current, world-wide coronavirus disease 2019 (COVID-19) pandemic. Angiotensin-converting enzyme 2 (ACE2) is the SARS-CoV-2 host entry receptor for cellular inoculation and target organ injury. We reviewed ACE2 expression and the role of ACE2-angiotensin 1-7-Mas receptor axis activity in abdominal aortic aneurysm (AAA) pathogenesis to identify potential COVID-19 influences on AAA disease pathogenesis. METHODS A comprehensive literature search was performed on PubMed, National Library of Medicine. Key words included COVID-19, SARS-CoV-2, AAA, ACE2, ACE or angiotensin II type 1 (AT1) receptor inhibitor, angiotensin 1-7, Mas receptor, age, gender, respiratory diseases, diabetes, and autoimmune diseases. Key publications on the epidemiology and pathogenesis of COVID-19 and AAAs were identified and reviewed. RESULTS All vascular structural cells, including endothelial and smooth muscle cells, fibroblasts, and pericytes express ACE2. Cigarette smoking, diabetes, chronic obstructive pulmonary disease, lupus, certain types of malignancies, and viral infection promote ACE2 expression and activity, with the magnitude of response varying by sex and age. Genetic deficiency of AT1 receptor, or pharmacologic ACE or AT1 inhibition also increases ACE2 and its catalytic product angiotensin 1-7. Genetic ablation or pharmacologic inhibition of ACE2 or Mas receptor augments, whereas ACE2 activation or angiotensin 1-7 treatment attenuates, progression of experimental AAAs. The potential influences of SARS-CoV-2 on AAA pathogenesis include augmented ACE-angiotensin II-AT1 receptor activity resulting from decreased reciprocal ACE2-angiotensin 1-7-Mas activation; increased production of proaneurysmal mediators stimulated by viral spike proteins in ACE2-negative myeloid cells or by ACE2-expressing vascular structural cells; augmented local or systemic cross-talk between viral targeted nonvascular, nonleukocytic ACE2-expressing cells via ligand recognition of their cognate leukocyte receptors; and hypoxemia and increased systemic inflammatory tone experienced during severe COVID-19 illness. CONCLUSIONS COVID-19 may theoretically influence AAA disease through multiple SARS-CoV-2-induced mechanisms. Further investigation and clinical follow-up will be necessary to determine whether and to what extent the COVID-19 pandemic will influence the prevalence, progression, and lethality of AAA disease in the coming decade.
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Affiliation(s)
- Baohui Xu
- Department of Surgery, Stanford University School of Medicine, Stanford, Calif.
| | - Gang Li
- Department of Surgery, Stanford University School of Medicine, Stanford, Calif
| | - Jia Guo
- Department of Surgery, Stanford University School of Medicine, Stanford, Calif
| | - Toru Ikezoe
- Department of Surgery, Stanford University School of Medicine, Stanford, Calif
| | | | - Sihai Zhao
- Department of Surgery, Stanford University School of Medicine, Stanford, Calif
| | - Ronald L Dalman
- Department of Surgery, Stanford University School of Medicine, Stanford, Calif
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9
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Loo DDF, Wright EM. Regulation of Neutral Amino Acid Transport By the SARS-CoV-2 Receptor ACE2. FUNCTION (OXFORD, ENGLAND) 2021; 2:zqab048. [PMID: 34642665 PMCID: PMC8499944 DOI: 10.1093/function/zqab048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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10
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Fairweather SJ, Rajendran E, Blume M, Javed K, Steinhöfel B, McConville MJ, Kirk K, Bröer S, van Dooren GG. Coordinated action of multiple transporters in the acquisition of essential cationic amino acids by the intracellular parasite Toxoplasma gondii. PLoS Pathog 2021; 17:e1009835. [PMID: 34432856 PMCID: PMC8423306 DOI: 10.1371/journal.ppat.1009835] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 09/07/2021] [Accepted: 07/23/2021] [Indexed: 02/07/2023] Open
Abstract
Intracellular parasites of the phylum Apicomplexa are dependent on the scavenging of essential amino acids from their hosts. We previously identified a large family of apicomplexan-specific plasma membrane-localized amino acid transporters, the ApiATs, and showed that the Toxoplasma gondii transporter TgApiAT1 functions in the selective uptake of arginine. TgApiAT1 is essential for parasite virulence, but dispensable for parasite growth in medium containing high concentrations of arginine, indicating the presence of at least one other arginine transporter. Here we identify TgApiAT6-1 as the second arginine transporter. Using a combination of parasite assays and heterologous characterisation of TgApiAT6-1 in Xenopus laevis oocytes, we demonstrate that TgApiAT6-1 is a general cationic amino acid transporter that mediates both the high-affinity uptake of lysine and the low-affinity uptake of arginine. TgApiAT6-1 is the primary lysine transporter in the disease-causing tachyzoite stage of T. gondii and is essential for parasite proliferation. We demonstrate that the uptake of cationic amino acids by TgApiAT6-1 is ‘trans-stimulated’ by cationic and neutral amino acids and is likely promoted by an inwardly negative membrane potential. These findings demonstrate that T. gondii has evolved overlapping transport mechanisms for the uptake of essential cationic amino acids, and we draw together our findings into a comprehensive model that highlights the finely-tuned, regulated processes that mediate cationic amino acid scavenging by these intracellular parasites. The causative agent of toxoplasmosis, Toxoplasma gondii, is a versatile intracellular parasite that can proliferate within nucleated cells of warm-blooded organisms. In order to survive, T. gondii parasites must scavenge the cationic amino acids lysine and arginine from their hosts. In a previous study, we demonstrated that a plasma membrane-localized protein called TgApiAT1 facilitates the uptake of arginine into the parasite. We found that parasites lacking TgApiAT1 could proliferate when cultured in medium containing high concentrations of arginine, suggesting the existence of an additional uptake pathway for arginine. In the present study, we demonstrate that this second uptake pathway is mediated by TgApiAT6-1, a protein belonging to the same solute transporter family as TgApiAT1. We show that TgApiAT6-1 is the major lysine transporter of the parasite, and that it is critical for parasite proliferation. Furthermore, we demonstrate that TgApiAT6-1 can transport arginine into parasites under conditions in which arginine concentrations are high and lysine concentrations are comparatively lower. These data support a model for the finely-tuned acquisition of essential cationic amino acids that involves multiple transporters, and which likely contributes to these parasites being able to survive and proliferate within a wide variety of host cell types.
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Affiliation(s)
- Stephen J. Fairweather
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
- * E-mail: (SJF); (GGvD)
| | - Esther Rajendran
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Martin Blume
- Department of Biochemistry and Molecular Biology and the Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
- Robert Koch Institute, Berlin, Germany
| | - Kiran Javed
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Birte Steinhöfel
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
- Humboldt University Berlin, Berlin, Germany
| | - Malcolm J. McConville
- Department of Biochemistry and Molecular Biology and the Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, Victoria, Australia
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Stefan Bröer
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Giel G. van Dooren
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
- * E-mail: (SJF); (GGvD)
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11
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Castagna M, Cinquetti R, Verri T, Vacca F, Giovanola M, Barca A, Romanazzi T, Roseti C, Galli A, Bossi E. The Lepidopteran KAAT1 and CAATCH1: Orthologs to Understand Structure-Function Relationships in Mammalian SLC6 Transporters. Neurochem Res 2021; 47:111-126. [PMID: 34304372 PMCID: PMC8310414 DOI: 10.1007/s11064-021-03410-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 04/18/2021] [Accepted: 07/20/2021] [Indexed: 11/16/2022]
Abstract
To the SLC6 family belong 20 human transporters that utilize the sodium electrochemical gradient to move biogenic amines, osmolytes, amino acids and related compounds into cells. They are classified into two functional groups, the Neurotransmitter transporters (NTT) and Nutrient amino acid transporters (NAT). Here we summarize how since their first cloning in 1998, the insect (Lepidopteran) Orthologs of the SLC6 family transporters have represented very important tools for investigating functional–structural relationships, mechanism of transport, ion and pH dependence and substate interaction of the mammalian (and human) counterparts.
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Affiliation(s)
- Michela Castagna
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via Trentacoste 2, 20134, Milan, Italy
| | - Raffaella Cinquetti
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, via Dunant 3, 21100, Varese, Italy
| | - Tiziano Verri
- Laboratory of Applied Physiology, Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Provinciale Lecce-Monteroni, 73100, Lecce, Italy
| | - Francesca Vacca
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, via Dunant 3, 21100, Varese, Italy
| | - Matteo Giovanola
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via Trentacoste 2, 20134, Milan, Italy
| | - Amilcare Barca
- Laboratory of Applied Physiology, Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Provinciale Lecce-Monteroni, 73100, Lecce, Italy
| | - Tiziana Romanazzi
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, via Dunant 3, 21100, Varese, Italy
| | - Cristina Roseti
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, via Dunant 3, 21100, Varese, Italy.,Research Centre for Neuroscience, University of Insubria, Varese, Italy
| | - Alessandra Galli
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Via Trentacoste 2, 20134, Milan, Italy
| | - Elena Bossi
- Laboratory of Cellular and Molecular Physiology, Department of Biotechnology and Life Sciences, University of Insubria, via Dunant 3, 21100, Varese, Italy. .,Research Centre for Neuroscience, University of Insubria, Varese, Italy.
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12
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Rey F. Structure-function relations of the SARS-CoV-2 spike protein and impact of mutations in the variants of concern. C R Biol 2021; 344:77-110. [PMID: 34213849 DOI: 10.5802/crbiol.53] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This review covers the main features of the severe acquired respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein, its interaction with the main entry receptor, the human angiotensin converting enzyme 2 (ACE2), and the subsequent membrane fusion step. The focus is on the structural organization of these proteins and mechanistic aspects of their interactions that lead to cytoplasmic release of the viral genome. The most potently neutralizing antibodies against SARS-CoV-2 were shown to interfere with the spike/ACE2 interaction. I thus also review the location and the potential impact of mutations in the spike protein observed in the variants of concern that emerged concomitantly with acquired immunity in the population after one year of virus circulation. Understanding how these interactions affect the spike/ACE2 interactions and the subsequent spike-protein-induced membrane fusion reaction is important to stay one step ahead of the virus evolution and develop efficient countermeasures.
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Affiliation(s)
- Félix Rey
- Unité de Virologie Structurale, CNRS UMR 3569, Institut Pasteur, 28 rue du Dr Roux, 75015 Paris, France
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13
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Stevens BR, Ellory JC, Preston RL. B 0AT1 Amino Acid Transporter Complexed With SARS-CoV-2 Receptor ACE2 Forms a Heterodimer Functional Unit: In Situ Conformation Using Radiation Inactivation Analysis. FUNCTION 2021; 2:zqab027. [PMID: 34847569 PMCID: PMC8194517 DOI: 10.1093/function/zqab027] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/04/2021] [Accepted: 05/11/2021] [Indexed: 01/06/2023] Open
Abstract
The SARS-CoV-2 receptor, angiotensin-converting enzyme-2 (ACE2), is expressed at levels of greatest magnitude in the small intestine as compared with all other human tissues. Enterocyte ACE2 is coexpressed as the apical membrane trafficking partner obligatory for expression and activity of the B0AT1 sodium-dependent neutral amino acid transporter. These components are assembled as an [ACE2:B0AT1]2 dimer-of-heterodimers quaternary complex that putatively steers SARS-CoV-2 tropism in the gastrointestinal (GI) tract. GI clinical symptomology is reported in about half of COVID-19 patients, and can be accompanied by gut shedding of virion particles. We hypothesized that within this 4-mer structural complex, each [ACE2:B0AT1] heterodimer pair constitutes a physiological "functional unit." This was confirmed experimentally by employing purified lyophilized enterocyte brush border membrane vesicles exposed to increasing doses of high-energy electron radiation from a 16 MeV linear accelerator. Based on radiation target theory, the results indicated the presence of Na+-dependent neutral amino acid influx transport activity functional unit with target size molecular weight 183.7 ± 16.8 kDa in situ in intact apical membranes. Each thermodynamically stabilized [ACE2:B0AT1] heterodimer functional unit manifests the transport activity within the whole ∼345 kDa [ACE2:B0AT1]2 dimer-of-heterodimers quaternary structural complex. The results are consistent with our prior molecular docking modeling and gut-lung axis approaches to understanding COVID-19. These findings advance understanding the physiology of B0AT1 interaction with ACE2 in the gut, and thereby contribute to translational developments designed to treat or mitigate COVID-19 variant outbreaks and/or GI symptom persistence in long-haul postacute sequelae of SARS-CoV-2.
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Affiliation(s)
- Bruce R Stevens
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, FL, 32610, USA
- Department of Medicine, Division of Gastroenterology, University of Florida College of Medicine, Gainesville, FL, 32610, USA
| | - J Clive Ellory
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Robert L Preston
- School of Biological Sciences, Illinois State University, Normal, IL, 61790, USA
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14
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Gerbeth-Kreul C, Pommereau A, Ruf S, Kane JL, Kuntzweiler T, Hessler G, Engel CK, Shum P, Wei L, Czech J, Licher T. A Solid Supported Membrane-Based Technology for Electrophysical Screening of B 0AT1-Modulating Compounds. SLAS DISCOVERY 2021; 26:783-797. [PMID: 33955247 DOI: 10.1177/24725552211011180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Classical high-throughput screening (HTS) technologies for the analysis of ionic currents across biological membranes can be performed using fluorescence-based, radioactive, and mass spectrometry (MS)-based uptake assays. These assays provide rapid results for pharmacological HTS, but the underlying, indirect analytical character of these assays can be linked to high false-positive hit rates. Thus, orthogonal and secondary assays using more biological target-based technologies are indispensable for further compound validation and optimization. Direct assay technologies for transporter proteins are electrophysiology-based, but are also complex, time-consuming, and not well applicable for automated profiling purposes. In contrast to conventional patch clamp systems, solid supported membrane (SSM)-based electrophysiology is a sensitive, membrane-based method for transporter analysis, and current technical developments target the demand for automated, accelerated, and sensitive assays for transporter-directed compound screening. In this study, the suitability of the SSM-based technique for pharmacological compound identification and optimization was evaluated performing cell-free SSM-based measurements with the electrogenic amino acid transporter B0AT1 (SLC6A19). Electrophysiological characterization of leucine-induced currents demonstrated that the observed signals were specific to B0AT1. Moreover, B0AT1-dependent responses were successfully inhibited using an established in-house tool compound. Evaluation of current stability and data reproducibility verified the robustness and reliability of the applied assay. Active compounds from primary screens of large compound libraries were validated, and false-positive hits were identified. These results clearly demonstrate the suitability of the SSM-based technique as a direct electrophysiological method for rapid and automated identification of small molecules that can inhibit B0AT1 activity.
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Affiliation(s)
- Carolin Gerbeth-Kreul
- In Vitro Biology & High-throughput Chemistry, Integrated Drug Discovery, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
| | - Antje Pommereau
- In Vitro Biology & High-throughput Chemistry, Integrated Drug Discovery, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
| | - Sven Ruf
- Synthetic Molecular Design, Integrated Drug Discovery, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
| | - John L Kane
- Medicinal Chemistry, Integrated Drug Discovery, Sanofi-Genzyme, Waltham, MA, USA
| | - Theresa Kuntzweiler
- In Vitro Biology, Integrated Drug Discovery, Sanofi-Genzyme, Waltham, MA, USA
| | - Gerhard Hessler
- Synthetic Molecular Design, Integrated Drug Discovery, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
| | - Christian K Engel
- Synthetic Molecular Design, Integrated Drug Discovery, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
| | - Patrick Shum
- Medicinal Chemistry, Integrated Drug Discovery, Sanofi-Genzyme, Waltham, MA, USA
| | - LinLi Wei
- Medicinal Chemistry, Integrated Drug Discovery, Sanofi-Genzyme, Waltham, MA, USA
| | - Joerg Czech
- In Vitro Biology & High-throughput Chemistry, Integrated Drug Discovery, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
| | - Thomas Licher
- In Vitro Biology & High-throughput Chemistry, Integrated Drug Discovery, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany
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15
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Fairweather SJ, Okada S, Gauthier-Coles G, Javed K, Bröer A, Bröer S. A GC-MS/Single-Cell Method to Evaluate Membrane Transporter Substrate Specificity and Signaling. Front Mol Biosci 2021; 8:646574. [PMID: 33928121 PMCID: PMC8076599 DOI: 10.3389/fmolb.2021.646574] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 02/17/2021] [Indexed: 12/18/2022] Open
Abstract
Amino acid transporters play a vital role in metabolism and nutrient signaling pathways. Typically, transport activity is investigated using single substrates and competing amounts of other amino acids. We used GC-MS and LC-MS for metabolic screening of Xenopus laevis oocytes expressing various human amino acid transporters incubated in complex media to establish their comprehensive substrate profiles. For most transporters, amino acid selectivity matched reported substrate profiles. However, we could not detect substantial accumulation of cationic amino acids by SNAT4 and ATB0,+ in contrast to previous reports. In addition, comparative substrate profiles of two related sodium neutral amino acid transporters known as SNAT1 and SNAT2, revealed the latter as a significant leucine accumulator. As a consequence, SNAT2, but not SNAT1, was shown to be an effective activator of the eukaryotic cellular growth regulator mTORC1. We propose, that metabolomic profiling of membrane transporters in Xe nopus laevis oocytes can be used to test their substrate specificity and role in intracellular signaling pathways.
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Affiliation(s)
- Stephen J. Fairweather
- Research School of Biology, Australian National University, Canberra, ACT, Australia
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia
| | - Shoko Okada
- Commonwealth Scientific and Industrial Research Institute (CSIRO) Land and Water, Canberra, ACT, Australia
| | | | - Kiran Javed
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Angelika Bröer
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Stefan Bröer
- Research School of Biology, Australian National University, Canberra, ACT, Australia
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16
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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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17
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Bian J, Li Z. Angiotensin-converting enzyme 2 (ACE2): SARS-CoV-2 receptor and RAS modulator. Acta Pharm Sin B 2021; 11:1-12. [PMID: 33072500 PMCID: PMC7553008 DOI: 10.1016/j.apsb.2020.10.006] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 08/29/2020] [Accepted: 09/07/2020] [Indexed: 01/08/2023] Open
Abstract
The coronavirus disease 2019 (COVID-19) outbreak is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Angiotensin-converting enzyme 2 (ACE2) was rapidly identified as the critical functional receptor for SARS-CoV-2. ACE2 is well-known as a counter-regulator of the renin-angiotensin system (RAS) and plays a key role in the cardiovascular system. Given that ACE2 functions as both a SARS-CoV-2 receptor and a RAS modulator, the treatment for COVID-19 presents a dilemma of how to limit virus entry but protect ACE2 physiological functions. Thus, an in-depth summary of the recent progress of ACE2 research and its relationship to the virus is urgently needed to provide possible solution to the dilemma. Here, we summarize the complexity and interplay between the coronavirus, ACE2 and RAS (including anti-RAS drugs). We propose five novel working modes for functional receptor for SARS-CoV-2 infection and the routes of ACE2-mediated virus entering host cells, as well as its regulatory mechanism. For the controversy of anti-RAS drugs application, we also give theoretical analysis and discussed for drug application. These will contribute to a deeper understanding of the complex mechanisms of underlying the relationship between the virus and ACE2, and provide guidance for virus intervention strategies.
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Affiliation(s)
- Jingwei Bian
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital; Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health; Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education; Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China
| | - Zijian Li
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital; Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health; Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education; Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing 100191, China
- Department of Pharmacy, Peking University Third Hospital, Beijing 100191, China
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18
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ACE2, angiotensin 1-7 and skeletal muscle: review in the era of COVID-19. Clin Sci (Lond) 2020; 134:3047-3062. [PMID: 33231620 PMCID: PMC7687025 DOI: 10.1042/cs20200486] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 12/12/2022]
Abstract
Angiotensin converting enzyme-2 (ACE2) is a multifunctional transmembrane protein recently recognised as the entry receptor of the virus causing COVID-19. In the renin–angiotensin system (RAS), ACE2 cleaves angiotensin II (Ang II) into angiotensin 1-7 (Ang 1-7), which is considered to exert cellular responses to counteract the activation of the RAS primarily through a receptor, Mas, in multiple organs including skeletal muscle. Previous studies have provided abundant evidence suggesting that Ang 1-7 modulates multiple signalling pathways leading to protection from pathological muscle remodelling and muscle insulin resistance. In contrast, there is relatively little evidence to support the protective role of ACE2 in skeletal muscle. The potential contribution of endogenous ACE2 to the regulation of Ang 1-7-mediated protection of these muscle pathologies is discussed in this review. Recent studies have suggested that ACE2 protects against ageing-associated muscle wasting (sarcopenia) through its function to modulate molecules outside of the RAS. Thus, the potential association of sarcopenia with ACE2 and the associated molecules outside of RAS is also presented herein. Further, we introduce the transcriptional regulation of muscle ACE2 by drugs or exercise, and briefly discuss the potential role of ACE2 in the development of COVID-19.
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19
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Abstract
Many research teams all over the world focus their research on the SARS-CoV-2, the new coronavirus that causes the so-called COVID-19 disease. Most of the studies identify the main protease or 3C-like protease (Mpro/3CLpro) as a valid target for large-spectrum inhibitors. Also, the interaction of the human receptor angiotensin-converting enzyme 2 (ACE2) with the viral surface glycoprotein (S) is studied in depth. Structural studies tried to identify the residues responsible for enhancement/weaken virus-ACE2 interactions or the cross-reactivity of the neutralizing antibodies. Although the understanding of the immune system and the hyper-inflammatory process in COVID-19 are crucial for managing the immediate and the long-term consequences of the disease, not many X-ray/NMR/cryo-EM crystals are available. In addition to 3CLpro, the crystal structures of other nonstructural proteins offer valuable information for elucidating some aspects of the SARS-CoV-2 infection. Thus, the structural analysis of the SARS-CoV-2 is currently mainly focused on three directions-finding Mpro/3CLpro inhibitors, the virus-host cell invasion, and the virus-neutralizing antibody interaction.
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Affiliation(s)
- Mihaela Ileana Ionescu
- Department of Microbiology, Iuliu Hațieganu University of Medicine and Pharmacy, 6 Louis Pasteur, 400349, Cluj-Napoca, Romania.
- Department of Microbiology, County Emergency Clinical Hospital, 400006, Cluj-Napoca, Romania.
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20
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Descamps G, Verset L, Trelcat A, Hopkins C, Lechien JR, Journe F, Saussez S. ACE2 Protein Landscape in the Head and Neck Region: The Conundrum of SARS-CoV-2 Infection. BIOLOGY 2020; 9:E235. [PMID: 32824830 PMCID: PMC7465650 DOI: 10.3390/biology9080235] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/04/2020] [Accepted: 08/14/2020] [Indexed: 01/08/2023]
Abstract
The coronavirus pandemic raging worldwide since December 2019 is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which invades human cells via the angiotensin-converting enzyme 2 (ACE2) receptor. Although it has already been identified in many organs, ACE2 expression remains largely unknown in the head and neck (HN) sphere. Thus, this study aims to investigate its protein expression in several sites of the upper aerodigestive tract in order to highlight potential routes of infection. We compared ACE2 immunohistochemical expression between 70 paraffin-embedded specimens with two different antibodies and reported the quantified expression in each histological location. Surprisingly, we obtained different results depending on the antibody, an absence of labeling having been observed with a monoclonal antibody raised against the extracellular domain, whereas the polyclonal, against the cytoplasmic part of the protein, revealed enriched ACE2 expression, particularly in sinuses, vocal cords, salivary glands and oral cavity epithelial cells. The interpretation of these discordant results has brought several exciting lines of reflection. In conclusion, this study provides possible routes of entry for the SARS-CoV-2 in HN region and, above all, has led us to encourage caution when studying the ACE2 expression which is currently at the center of all attention.
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Affiliation(s)
- Géraldine Descamps
- Department of Human Anatomy and Experimental Oncology, Faculty of Medicine and Pharmacy, UMONS Research Institute for Health Sciences and Technology, University of Mons (UMONS), Avenue du Champ de Mars 6, 7000 Mons, Belgium; (G.D.); (A.T.); (J.R.L.); (F.J.)
| | - Laurine Verset
- Department of Pathology, Institute Jules Bordet, Université Libre de Bruxelles, Rue Héger-Bordet 1, 1000 Brussels, Belgium;
| | - Anne Trelcat
- Department of Human Anatomy and Experimental Oncology, Faculty of Medicine and Pharmacy, UMONS Research Institute for Health Sciences and Technology, University of Mons (UMONS), Avenue du Champ de Mars 6, 7000 Mons, Belgium; (G.D.); (A.T.); (J.R.L.); (F.J.)
| | - Claire Hopkins
- Guy’s and St Thomas’ Hospitals, Westminster Bridge Road, London SE1 9RT, UK;
- British Rhinological Society (President), 35-43 Lincoln's Inn Fields, London WC2A 3PE, UK
| | - Jérome R. Lechien
- Department of Human Anatomy and Experimental Oncology, Faculty of Medicine and Pharmacy, UMONS Research Institute for Health Sciences and Technology, University of Mons (UMONS), Avenue du Champ de Mars 6, 7000 Mons, Belgium; (G.D.); (A.T.); (J.R.L.); (F.J.)
- Department of Otolaryngology-Head & Neck Surgery, Foch Hospital, School of Medicine, UFR Simone Veil, Université Versailles Saint-Quentin-en-Yvelines (Paris Saclay University), 40 Rue Worth, Suresnes, 92150 Paris, France
- Department of Otorhinolaryngology and Head and Neck Surgery, CHU de Bruxelles, CHU Saint-Pierre, Université Libre de Bruxelles, Rue aux Laines 105, 1000 Brussels, Belgium
| | - Fabrice Journe
- Department of Human Anatomy and Experimental Oncology, Faculty of Medicine and Pharmacy, UMONS Research Institute for Health Sciences and Technology, University of Mons (UMONS), Avenue du Champ de Mars 6, 7000 Mons, Belgium; (G.D.); (A.T.); (J.R.L.); (F.J.)
- Department of Oncology and Experimental Surgery, Institute Jules Bordet (IJB), Université Libre de Bruxelles (ULB), Rue Heger-Bordet 1, 1000 Brussels, Belgium
| | - Sven Saussez
- Department of Human Anatomy and Experimental Oncology, Faculty of Medicine and Pharmacy, UMONS Research Institute for Health Sciences and Technology, University of Mons (UMONS), Avenue du Champ de Mars 6, 7000 Mons, Belgium; (G.D.); (A.T.); (J.R.L.); (F.J.)
- Department of Otorhinolaryngology and Head and Neck Surgery, CHU de Bruxelles, CHU Saint-Pierre, Université Libre de Bruxelles, Rue aux Laines 105, 1000 Brussels, Belgium
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21
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Pan X, Zeng T, Zhang YH, Chen L, Feng K, Huang T, Cai YD. Investigation and Prediction of Human Interactome Based on Quantitative Features. Front Bioeng Biotechnol 2020; 8:730. [PMID: 32766217 PMCID: PMC7379396 DOI: 10.3389/fbioe.2020.00730] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Accepted: 06/09/2020] [Indexed: 01/27/2023] Open
Abstract
Protein is one of the most significant components of all living creatures. All significant and essential biological structures and functions relies on proteins and their respective biological functions. However, proteins cannot perform their unique biological significance independently. They have to interact with each other to realize the complicated biological processes in all living creatures including human beings. In other words, proteins depend on interactions (protein-protein interactions) to realize their significant effects. Thus, the significance comparison and quantitative contribution of candidate PPI features must be determined urgently. According to previous studies, 258 physical and chemical characteristics of proteins have been reported and confirmed to definitively affect the interaction efficiency of the related proteins. Among such features, essential physiochemical features of proteins like stoichiometric balance, protein abundance, molecular weight and charge distribution have been validated to be quite significant and irreplaceable for protein-protein interactions (PPIs). Therefore, in this study, we, on one hand, presented a novel computational framework to identify the key factors affecting PPIs with Boruta feature selection (BFS), Monte Carlo feature selection (MCFS), incremental feature selection (IFS), and on the other hand, built a quantitative decision-rule system to evaluate the potential PPIs under real conditions with random forest (RF) and RIPPER algorithms, thereby supplying several new insights into the detailed biological mechanisms of complicated PPIs. The main datasets and codes can be downloaded at https://github.com/xypan1232/Mass-PPI.
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Affiliation(s)
- Xiaoyong Pan
- School of Life Sciences, Shanghai University, Shanghai, China.,Key Laboratory of System Control and Information Processing, Ministry of Education of China, Institute of Image Processing and Pattern Recognition, Shanghai Jiao Tong University, Shanghai, China
| | - Tao Zeng
- Key Laboratory of Systems Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
| | - Yu-Hang Zhang
- Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Lei Chen
- College of Information Engineering, Shanghai Maritime University, Shanghai, China
| | - Kaiyan Feng
- Department of Computer Science, Guangdong AIB Polytechnic, Guangzhou, China
| | - Tao Huang
- Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yu-Dong Cai
- School of Life Sciences, Shanghai University, Shanghai, China
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22
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Yadav A, Shah N, Tiwari PK, Javed K, Cheng Q, Aidhen IS, Bröer S. Novel Chemical Scaffolds to Inhibit the Neutral Amino Acid Transporter B 0AT1 (SLC6A19), a Potential Target to Treat Metabolic Diseases. Front Pharmacol 2020; 11:140. [PMID: 32180718 PMCID: PMC7059793 DOI: 10.3389/fphar.2020.00140] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/03/2020] [Indexed: 11/13/2022] Open
Abstract
Lack of B0AT1 (SLC6A19) partially protects mice against the onset of non-alcoholic steatohepatitis (NASH). To achieve a similar outcome through pharmacological treatment, we improved previously identified inhibitors of B0AT1 by medicinal chemistry and identified second generation inhibitors by high through-put screening. Modified diarylmethine compounds inhibited B0AT1 with IC50 values ranging from 8-90 μM. A second generation of inhibitors was derived from high-throughput screening and showed higher affinity (IC50 of 1-15 μM) and strong selectivity against amino acid transporters with similar substrate specificity, such as ASCT2 (SLC1A5) and LAT1 (SLC7A5). All compounds were unrelated to B0AT1 substrates, but were likely to bind in the vicinity of the substrate binding site.
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Affiliation(s)
- Aditya Yadav
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Nishank Shah
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | | | - Kiran Javed
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Qi Cheng
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | | | - Stefan Bröer
- Research School of Biology, Australian National University, Canberra, ACT, Australia
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23
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Pillai NR, Yubero D, Shayota BJ, Oyarzábal A, Ghosh R, Sun Q, Azamian MS, Arjona C, Brandi N, Palau F, Lalani SR, Artuch R, García‐Cazorla A, Scott DA. Loss of CLTRN function produces a neuropsychiatric disorder and a biochemical phenotype that mimics Hartnup disease. Am J Med Genet A 2019; 179:2459-2468. [DOI: 10.1002/ajmg.a.61357] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/22/2019] [Accepted: 08/25/2019] [Indexed: 01/02/2023]
Affiliation(s)
- Nishitha R. Pillai
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
- Texas Children's Hospital Houston Texas
| | - Delia Yubero
- Department of Genetics and Molecular Medicine‐IPER, Institut de Recerca Sant Joan de Déu and CIBERER (ISCIII) Hospital Sant Joan de Déu Barcelona Spain
| | - Brian J. Shayota
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
- Texas Children's Hospital Houston Texas
| | - Alfonso Oyarzábal
- Laboratory of Synaptic Metabolism, Institut de Recerca Sant Joan de Déu and CIBERER (ISCIII) Hospital Sant Joan de Déu Barcelona Spain
| | - Rajarshi Ghosh
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
- Baylor Genetics Laboratory Houston Texas
| | - Qin Sun
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
- Baylor Genetics Laboratory Houston Texas
| | - Mahshid S. Azamian
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
- Texas Children's Hospital Houston Texas
| | - Cesar Arjona
- Department of Genetics and Molecular Medicine‐IPER, Institut de Recerca Sant Joan de Déu and CIBERER (ISCIII) Hospital Sant Joan de Déu Barcelona Spain
| | - Núria Brandi
- Department of Genetics and Molecular Medicine‐IPER, Institut de Recerca Sant Joan de Déu and CIBERER (ISCIII) Hospital Sant Joan de Déu Barcelona Spain
- School of Medicine Universitat de Barcelona Barcelona Spain
| | - Francesc Palau
- Department of Genetics and Molecular Medicine‐IPER, Institut de Recerca Sant Joan de Déu and CIBERER (ISCIII) Hospital Sant Joan de Déu Barcelona Spain
- Division of Pediatrics University of Barcelona School of Medicine and Health Sciences, and Institute of Medicine and Dermatology, Hospital Clínic Barcelona Spain
| | - Seema R. Lalani
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
- Texas Children's Hospital Houston Texas
| | - Rafael Artuch
- Department of Clinical Biochemistry, Institut de Recerca Sant Joan de Déu and CIBERER (ISCIII) Hospital Sant Joan de Déu Barcelona Spain
| | - Angeles García‐Cazorla
- Laboratory of Synaptic Metabolism, Institut de Recerca Sant Joan de Déu and CIBERER (ISCIII) Hospital Sant Joan de Déu Barcelona Spain
- Neurometabolic Unit, Department of Neurology Institut de Recerca, Sant Joan de Déu metabERN and CIBERER (ISCIII), Hospital Sant Joan de Déu Barcelona Spain
| | - Daryl A. Scott
- Department of Molecular and Human Genetics Baylor College of Medicine Houston Texas
- Texas Children's Hospital Houston Texas
- Department of Molecular Physiology and Biophysics Baylor College of Medicine Houston Texas
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24
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Richards EM, Raizada MK. ACE2 and pACE2: A Pair of Aces for Pulmonary Arterial Hypertension Treatment? Am J Respir Crit Care Med 2019; 198:422-423. [PMID: 29634285 DOI: 10.1164/rccm.201803-0569ed] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
- Elaine M Richards
- 1 Department of Physiology and Functional Genomics University of Florida College of Medicine Gainesville, Florida
| | - Mohan K Raizada
- 1 Department of Physiology and Functional Genomics University of Florida College of Medicine Gainesville, Florida
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25
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Bouchard C, Boudko DY, Jiang RHY. A SLC6 transporter cloned from the lion's mane jellyfish (Cnidaria, Scyphozoa) is expressed in neurons. PLoS One 2019; 14:e0218806. [PMID: 31233570 PMCID: PMC6590891 DOI: 10.1371/journal.pone.0218806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 06/10/2019] [Indexed: 11/18/2022] Open
Abstract
In the course of recent comparative genomic studies conducted on nervous systems across the phylogeny, current thinking is leaning in favor of more heterogeneity among nervous systems than what was initially expected. The isolation and characterization of molecular components that constitute the cnidarian neuron is not only of interest to the physiologist but also, on a larger scale, to those who study the evolution of nervous systems. Understanding the function of those ancient neurons involves the identification of neurotransmitters and their precursors, the description of nutrients used by neurons for metabolic purposes and the identification of integral membrane proteins that bind to those compounds. Using a molecular cloning strategy targeting membrane proteins that are known to be present in all forms of life, we isolated a member of the solute carrier family 6 from the scyphozoan jellyfish Cyanea capillata. The phylogenetic analysis suggested that the new transporter sequence belongs to an ancestral group of the nutrient amino acid transporter subfamily and is part of a cluster of cnidarian sequences which may translocate the same substrate. We found that the jellyfish transporter is expressed in neurons of the motor nerve net of the animal. To this end, we established an in situ hybridization protocol for the tissues of C. capillata and developed a specific antibody to the jellyfish transporter. Finally, we showed that the gene that codes for the jellyfish transporter also expresses a long non-coding RNA. We hope that this research will contribute to studies that seek to understand what constitutes a neuron in species that belong to an ancient phylum.
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Affiliation(s)
- Christelle Bouchard
- College of Science and Mathematics, University of South Florida, Sarasota, Florida, United States of America
| | - Dmitri Y. Boudko
- Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, Chicago Medical School, North Chicago, Illinois, United States of America
| | - Rays H. Y. Jiang
- Global and Planetary Health, College of Public Health, University of South Florida USF Genomics Program, Tampa, Florida, United States of America
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26
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Schumann-Gillett A, Blyth MT, O’Mara ML. Is protein structure enough? A review of the role of lipids in SLC6 transporter function. Neurosci Lett 2019; 700:64-69. [DOI: 10.1016/j.neulet.2018.05.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 05/09/2018] [Accepted: 05/11/2018] [Indexed: 12/17/2022]
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27
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Amino acid transporters in the regulation of insulin secretion and signalling. Biochem Soc Trans 2019; 47:571-590. [PMID: 30936244 DOI: 10.1042/bst20180250] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 02/24/2019] [Accepted: 02/25/2019] [Indexed: 01/02/2023]
Abstract
Amino acids are increasingly recognised as modulators of nutrient disposal, including their role in regulating blood glucose through interactions with insulin signalling. More recently, cellular membrane transporters of amino acids have been shown to form a pivotal part of this regulation as they are primarily responsible for controlling cellular and circulating amino acid concentrations. The availability of amino acids regulated by transporters can amplify insulin secretion and modulate insulin signalling in various tissues. In addition, insulin itself can regulate the expression of numerous amino acid transporters. This review focuses on amino acid transporters linked to the regulation of insulin secretion and signalling with a focus on those of the small intestine, pancreatic β-islet cells and insulin-responsive tissues, liver and skeletal muscle. We summarise the role of the amino acid transporter B0AT1 (SLC6A19) and peptide transporter PEPT1 (SLC15A1) in the modulation of global insulin signalling via the liver-secreted hormone fibroblast growth factor 21 (FGF21). The role of vesicular vGLUT (SLC17) and mitochondrial SLC25 transporters in providing glutamate for the potentiation of insulin secretion is covered. We also survey the roles SNAT (SLC38) family and LAT1 (SLC7A5) amino acid transporters play in the regulation of and by insulin in numerous affective tissues. We hypothesise the small intestine amino acid transporter B0AT1 represents a crucial nexus between insulin, FGF21 and incretin hormone signalling pathways. The aim is to give an integrated overview of the important role amino acid transporters have been found to play in insulin-regulated nutrient signalling.
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28
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Parker KER, Fairweather SJ, Rajendran E, Blume M, McConville MJ, Bröer S, Kirk K, van Dooren GG. The tyrosine transporter of Toxoplasma gondii is a member of the newly defined apicomplexan amino acid transporter (ApiAT) family. PLoS Pathog 2019; 15:e1007577. [PMID: 30742695 PMCID: PMC6386423 DOI: 10.1371/journal.ppat.1007577] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 02/22/2019] [Accepted: 01/12/2019] [Indexed: 12/20/2022] Open
Abstract
Apicomplexan parasites are auxotrophic for a range of amino acids which must be salvaged from their host cells, either through direct uptake or degradation of host proteins. Here, we describe a family of plasma membrane-localized amino acid transporters, termed the Apicomplexan Amino acid Transporters (ApiATs), that are ubiquitous in apicomplexan parasites. Functional characterization of the ApiATs of Toxoplasma gondii indicate that several of these transporters are important for intracellular growth of the tachyzoite stage of the parasite, which is responsible for acute infections. We demonstrate that the ApiAT protein TgApiAT5-3 is an exchanger for aromatic and large neutral amino acids, with particular importance for L-tyrosine scavenging and amino acid homeostasis, and that TgApiAT5-3 is critical for parasite virulence. Our data indicate that T. gondii expresses additional proteins involved in the uptake of aromatic amino acids, and we present a model for the uptake and homeostasis of these amino acids. Our findings identify a family of amino acid transporters in apicomplexans, and highlight the importance of amino acid scavenging for the biology of this important phylum of intracellular parasites. The Apicomplexa comprise a large number of parasitic protozoa that have obligate intracellular lifestyles and cause significant human and animal diseases, including malaria, cryptosporidiosis, toxoplasmosis, coccidiosis in poultry, and various cattle fevers. Apicomplexans must scavenge essential nutrients from their hosts in order to proliferate and cause disease, including a range of amino acids. The direct uptake of these nutrients is presumed to be mediated by transporter proteins located in the plasma membrane of intracellular stages, although the identities of these proteins are poorly defined. Using a combination of bioinformatic, genetic, cell biological, and physiological approaches, we have characterized an apicomplexan-specific family of plasma membrane-localized transporter proteins that we have called the Apicomplexan Amino acid Transporters (ApiATs). We show that TgApiAT5-3, a member of the family in the apicomplexan Toxoplasma gondii, is an exchanger for aromatic and large neutral amino acids. In particular, it is critical for uptake of tyrosine, and for parasite virulence in a mouse infection model. We conclude that ApiATs are a family of plasma membrane transporters that play crucial roles in amino acid scavenging by apicomplexan parasites.
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Affiliation(s)
- Kathryn E. R. Parker
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | | | - Esther Rajendran
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Martin Blume
- Department of Biochemistry and Molecular Biology and the Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, VIC, Australia
- Robert Koch Institute, Berlin, Germany
| | - Malcolm J. McConville
- Department of Biochemistry and Molecular Biology and the Bio21 Institute of Molecular Science and Biotechnology, University of Melbourne, Parkville, VIC, Australia
| | - Stefan Bröer
- Research School of Biology, Australian National University, Canberra, ACT, Australia
- * E-mail: (GGVD); (KK); (SB)
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, ACT, Australia
- * E-mail: (GGVD); (KK); (SB)
| | - Giel G. van Dooren
- Research School of Biology, Australian National University, Canberra, ACT, Australia
- * E-mail: (GGVD); (KK); (SB)
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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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Belanger AM, Przybylska M, Gefteas E, Furgerson M, Geller S, Kloss A, Cheng SH, Zhu Y, Yew NS. Inhibiting neutral amino acid transport for the treatment of phenylketonuria. JCI Insight 2018; 3:121762. [PMID: 30046012 DOI: 10.1172/jci.insight.121762] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 06/19/2018] [Indexed: 12/21/2022] Open
Abstract
The neuropathological effects of phenylketonuria (PKU) stem from the inability of the body to metabolize excess phenylalanine (Phe), resulting in accumulation of Phe in the blood and brain. Since the kidney normally reabsorbs circulating amino acids with high efficiency, we hypothesized that preventing the renal uptake of Phe might provide a disposal pathway that could lower systemic Phe levels. SLC6A19 is a neutral amino acid transporter responsible for absorption of the majority of free Phe in the small intestine and reuptake of Phe by renal proximal tubule cells. Transgenic KO mice lacking SLC6A19 have elevated levels of Phe and other amino acids in their urine but are otherwise healthy. Here, we crossed the Pahenu2 mouse model of PKU with the Slc6a19-KO mouse. These mutant/KO mice exhibited abundant excretion of Phe in the urine and an approximately 70% decrease in plasma Phe levels. Importantly, brain Phe levels were decreased by 50%, and the levels of key neurotransmitters were increased in the mutant/KO mice. In addition, a deficit in spatial working memory and markers of neuropathology were corrected. Finally, treatment of Pahenu2 mice with Slc6a19 antisense oligonucleotides lowered Phe levels. The results suggest that inhibition of SLC6A19 may represent a novel approach for the treatment of PKU and related aminoacidopathies.
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MESH Headings
- Amines
- Amino Acid Transport Systems, Neutral/analysis
- Amino Acid Transport Systems, Neutral/genetics
- Amino Acid Transport Systems, Neutral/metabolism
- Amino Acids, Neutral/blood
- Amino Acids, Neutral/metabolism
- Animals
- Astrocytes/metabolism
- Astrocytes/pathology
- Biological Transport/drug effects
- Brain/metabolism
- Disease Models, Animal
- Female
- Gene Expression Regulation
- Genetic Diseases, Inborn/therapy
- Kidney Tubules, Proximal/drug effects
- Kidney Tubules, Proximal/metabolism
- Male
- Memory, Short-Term
- Mice
- Mice, Knockout
- Morpholinos/pharmacology
- Oligonucleotides/pharmacology
- Phenylalanine/blood
- Phenylalanine/metabolism
- Phenylketonurias/pathology
- Phenylketonurias/therapy
- Renal Reabsorption/drug effects
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31
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Orozco ZGA, Soma S, Kaneko T, Watanabe S. Spatial mRNA Expression and Response to Fasting and Refeeding of Neutral Amino Acid Transporters slc6a18 and slc6a19a in the Intestinal Epithelium of Mozambique tilapia. Front Physiol 2018; 9:212. [PMID: 29593569 PMCID: PMC5859172 DOI: 10.3389/fphys.2018.00212] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 02/26/2018] [Indexed: 12/17/2022] Open
Abstract
The mRNA expressions of the epithelial neutral amino acid transporters slc6a18 and slc6a19a in the five segments (HL, PMC, GL, DMC, and TS) of the intestine of Mozambique tilapia, and their responses to fasting and refeeding were investigated for a better understanding of the functional and nutritional characteristics of slc6a18 and slc6a19a. Although both slc6a18 and slc6a19a were expressed mainly in the intestine, these genes showed opposing spatial distributions along the intestine. The slc6a18 was mainly expressed in the middle (GL) and posterior (DMC and TS) intestines, while slc6a19a was specifically expressed in the anterior intestine (HL and PMC). Large decreases of amino acid concentrations from the HL to GL imply that amino acids are mainly absorbed before reaching the GL, suggesting an important role of slc6a19a in the absorption. Moreover, substantial amounts of some neutral amino acids with the isoelectric point close to 6 remain in the GL. These are most likely the remaining unabsorbed amino acids or those from of amino acid antiporters which release neutral amino acids in exchange for uptake of its substrates. These amino acids were diminished in the TS, suggesting active absorption in the posterior intestine. This suggests that slc6a18 is essential to complete the absorption of neutral amino acids. At fasting, significant downregulation of slc6a19a expression was observed from the initial up to day 2 and became stable from day 4 to day 14 in the HL and PMC suggesting that slc6a19a expression reflects nutritional condition in the intestinal lumen. Refeeding stimulates slc6a19a expression, although expressions did not exceed the initial level within 3 days after refeeding. The slc6a18 expression was decreased during fasting in the GL but no significant change was observed in the DMC. Only a transient decrease was observed at day 2 in the TS. Refeeding did not stimulate slc6a18 expression. Results in this study suggest that Slc6a18 and Slc6a19 have different roles in the intestine, and that both of these contribute to establish the efficient neutral amino acid absorption system in the tilapia.
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Affiliation(s)
- Zenith Gaye A Orozco
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Satoshi Soma
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Toyoji Kaneko
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Soichi Watanabe
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
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32
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Yang G, Chu PL, Rump LC, Le TH, Stegbauer J. ACE2 and the Homolog Collectrin in the Modulation of Nitric Oxide and Oxidative Stress in Blood Pressure Homeostasis and Vascular Injury. Antioxid Redox Signal 2017; 26:645-659. [PMID: 27889958 DOI: 10.1089/ars.2016.6950] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
SIGNIFICANCE Hypertension is the leading risk factor causing mortality and morbidity worldwide. Angiotensin (Ang) II, the most active metabolite of the renin-angiotensin system, plays an outstanding role in the pathogenesis of hypertension and vascular injury. Activation of angiotensin converting enzyme 2 (ACE2) has shown to attenuate devastating effects of Ang II in the cardiovascular system by reducing Ang II degradation and increasing Ang-(1-7) generation leading to Mas receptor activation. Recent Advances: Activation of the ACE2/Ang-(1-7)/Mas receptor axis reduces hypertension and improves vascular injury mainly through an increased nitric oxide (NO) bioavailability and decreased reactive oxygen species production. Recent studies reported that shedding of the enzymatically active ectodomain of ACE2 from the cell surface seems to regulate its activity and serves as an interorgan communicator in cardiovascular disease. In addition, collectrin, an ACE2 homolog with no catalytic activity, regulates blood pressure through an NO-dependent mechanism. CRITICAL ISSUES Large body of experimental data confirmed sustained beneficial effects of ACE2/Ang-(1-7)/Mas receptor axis activation on hypertension and vascular injury. Experimental studies also suggest that activation of collectrin might be beneficial in hypertension and endothelial dysfunction. Their role in clinical hypertension is unclear as selective and reliable activators of both axes are not yet available. FUTURE DIRECTIONS This review will highlight the results of recent research progress that illustrate the role of both ACE and collectrin in the modulation of NO and oxidative stress in blood pressure homeostasis and vascular injury, providing evidence for the potential therapeutic application of ACE2 and collectrin in hypertension and vascular disease. Antioxid. Redox Signal. 26, 645-659.
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Affiliation(s)
- Guang Yang
- 1 Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf , Düsseldorf, Germany
| | - Pei-Lun Chu
- 2 Division of Nephrology, Department of Medicine, University of Virginia , Charlottesville, Virginia.,3 Department of Internal Medicine, Graduate Institute of Biomedical and Pharmaceutical Science, College of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Lars C Rump
- 1 Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf , Düsseldorf, Germany
| | - Thu H Le
- 2 Division of Nephrology, Department of Medicine, University of Virginia , Charlottesville, Virginia
| | - Johannes Stegbauer
- 1 Department of Nephrology, Medical Faculty, Heinrich-Heine University Düsseldorf , Düsseldorf, Germany
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33
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Cheng Q, Shah N, Bröer A, Fairweather S, Jiang Y, Schmoll D, Corry B, Bröer S. Identification of novel inhibitors of the amino acid transporter B 0 AT1 (SLC6A19), a potential target to induce protein restriction and to treat type 2 diabetes. Br J Pharmacol 2017; 174:468-482. [PMID: 28176326 DOI: 10.1111/bph.13711] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 12/28/2016] [Accepted: 01/04/2017] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND AND PURPOSE The neutral amino acid transporter B0 AT1 (SLC6A19) has recently been identified as a possible target to treat type 2 diabetes and related disorders. B0 AT1 mediates the Na+ -dependent uptake of all neutral amino acids. For surface expression and catalytic activity, B0 AT1 requires coexpression of collectrin (TMEM27). In this study, we established tools to identify and evaluate novel inhibitors of B0 AT1. EXPERIMENTAL APPROACH A CHO-based cell line was generated, stably expressing collectrin and B0 AT1. Using this cell line, a high-throughput screening assay was developed, which uses a fluorescent dye to detect depolarisation of the cell membrane during amino acid uptake via B0 AT1. In parallel to these functional assays, we ran a computational compound screen using AutoDock4 and a homology model of B0 AT1 based on the high-resolution structure of the highly homologous Drosophila dopamine transporter. KEY RESULTS We characterized a series of novel inhibitors of the B0 AT1 transporter. Benztropine was identified as a competitive inhibitor of the transporter showing an IC50 of 44 ± 9 μM. The compound was selective with regard to related transporters and blocked neutral amino acid uptake in inverted sections of mouse intestine. CONCLUSION AND IMPLICATIONS The tools established in this study can be widely used to identify new transport inhibitors. Using these tools, we were able to identify compounds that can be used to study epithelial transport, to induce protein restriction, or be developed further through medicinal chemistry.
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Affiliation(s)
- Qi Cheng
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Nishank Shah
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Angelika Bröer
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Stephen Fairweather
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Yang Jiang
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Dieter Schmoll
- Industriepark Hoechst, Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | - Ben Corry
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Stefan Bröer
- Research School of Biology, The Australian National University, Canberra, Australia
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34
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Pei J, Grishin NV. Expansion of divergent SEA domains in cell surface proteins and nucleoporin 54. Protein Sci 2017; 26:617-630. [PMID: 27977898 DOI: 10.1002/pro.3096] [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: 10/08/2016] [Revised: 11/28/2016] [Accepted: 11/29/2016] [Indexed: 12/13/2022]
Abstract
SEA (sea urchin sperm protein, enterokinase, agrin) domains, many of which possess autoproteolysis activity, have been found in a number of cell surface and secreted proteins. Despite high sequence divergence, SEA domains were also proposed to be present in dystroglycan based on a conserved autoproteolysis motif and receptor-type protein phosphatase IA-2 based on structural similarity. The presence of a SEA domain adjacent to the transmembrane segment appears to be a recurring theme in quite a number of type I transmembrane proteins on the cell surface, such as MUC1, dystroglycan, IA-2, and Notch receptors. By comparative sequence and structural analyses, we identified dystroglycan-like proteins with SEA domains in Capsaspora owczarzaki of the Filasterea group, one of the closest single-cell relatives of metazoans. We also detected novel and divergent SEA domains in a variety of cell surface proteins such as EpCAM, α/ε-sarcoglycan, PTPRR, collectrin/Tmem27, amnionless, CD34, KIAA0319, fibrocystin-like protein, and a number of cadherins. While these proteins are mostly from metazoans or their single cell relatives such as choanoflagellates and Filasterea, fibrocystin-like proteins with SEA domains were found in several other eukaryotic lineages including green algae, Alveolata, Euglenozoa, and Haptophyta, suggesting an ancient evolutionary origin. In addition, the intracellular protein Nucleoporin 54 (Nup54) acquired a divergent SEA domain in choanoflagellates and metazoans.
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Affiliation(s)
| | - Nick V Grishin
- Howard Hughes Medical Institute.,Department of Biophysics and Department of Biochemistry, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, 75390, USA
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35
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Chu PL, Gigliotti JC, Cechova S, Bodonyi-Kovacs G, Chan F, Ralph DL, Howell N, Kalantari K, Klibanov AL, Carey RM, McDonough AA, Le TH. Renal Collectrin Protects against Salt-Sensitive Hypertension and Is Downregulated by Angiotensin II. J Am Soc Nephrol 2017; 28:1826-1837. [PMID: 28062568 DOI: 10.1681/asn.2016060675] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 11/28/2016] [Indexed: 12/13/2022] Open
Abstract
Collectrin, encoded by the Tmem27 gene, is a transmembrane glycoprotein with approximately 50% homology with angiotensin converting enzyme 2, but without a catalytic domain. Collectrin is most abundantly expressed in the kidney proximal tubule and collecting duct epithelia, where it has an important role in amino acid transport. Collectrin is also expressed in endothelial cells throughout the vasculature, where it regulates L-arginine uptake. We previously reported that global deletion of collectrin leads to endothelial dysfunction, augmented salt sensitivity, and hypertension. Here, we performed kidney crosstransplants between wild-type (WT) and collectrin knockout (Tmem27Y/- ) mice to delineate the specific contribution of renal versus extrarenal collectrin on BP regulation and salt sensitivity. On a high-salt diet, WT mice with Tmem27Y/- kidneys had the highest systolic BP and were the only group to exhibit glomerular mesangial hypercellularity. Additional studies showed that, on a high-salt diet, Tmem27Y/- mice had lower renal blood flow, higher abundance of renal sodium-hydrogen antiporter 3, and lower lithium clearance than WT mice. In WT mice, administration of angiotensin II for 2 weeks downregulated collectrin expression in a type 1 angiotensin II receptor-dependent manner. This downregulation coincided with the onset of hypertension, such that WT and Tmem27Y/- mice had similar levels of hypertension after 2 weeks of angiotensin II administration. Altogether, these data suggest that salt sensitivity is determined by intrarenal collectrin, and increasing the abundance or activity of collectrin may have therapeutic benefits in the treatment of hypertension and salt sensitivity.
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Affiliation(s)
| | - Joseph C Gigliotti
- Division of Nephrology.,Department of Integrated Physiology and Pharmacology, Liberty University College of Osteopathic Medicine, Lynchburg, Virginia; and
| | | | | | | | - Donna Lee Ralph
- Department of Cell and Neurobiology, University of Southern California, Keck School of Medicine, Los Angeles, California
| | - Nancy Howell
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, Virginia
| | | | | | - Robert M Carey
- Division of Endocrinology, Department of Medicine, University of Virginia Health System, Charlottesville, Virginia
| | - Alicia A McDonough
- Department of Cell and Neurobiology, University of Southern California, Keck School of Medicine, Los Angeles, California
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Freissmuth M, Stockner T, Sucic S. SLC6 Transporter Folding Diseases and Pharmacochaperoning. Handb Exp Pharmacol 2017; 245:249-270. [PMID: 29086036 DOI: 10.1007/164_2017_71] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The human genome encodes 19 genes of the solute carrier 6 (SLC6) family; non-synonymous changes in the coding sequence give rise to mutated transporters, which are misfolded and thus cause diseases in the affected individuals. Prominent examples include mutations in the transporters for dopamine (DAT, SLC6A3), for creatine (CT1, SLC6A8), and for glycine (GlyT2, SLC6A5), which result in infantile dystonia, mental retardation, and hyperekplexia, respectively. Thus, there is an obvious unmet medical need to identify compounds, which can remedy the folding deficit. The pharmacological correction of folding defects was originally explored in mutants of the serotonin transporter (SERT, SLC6A4), which were created to study the COPII-dependent export from the endoplasmic reticulum. This led to the serendipitous discovery of the pharmacochaperoning action of ibogaine. Ibogaine and its metabolite noribogaine also rescue several disease-relevant mutants of DAT. Because the pharmacology of DAT and SERT is exceptionally rich, it is not surprising that additional compounds have been identified, which rescue folding-deficient mutants. These compounds are not only of interest for restoring DAT function in the affected children. They are also likely to serve as useful tools to interrogate the folding trajectory of the transporter. This is likely to initiate a virtuous cycle: if the principles underlying folding of SLC6 transporters are understood, the design of pharmacochaperones ought to be facilitated.
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Affiliation(s)
- Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.
| | - Thomas Stockner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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Margheritis E, Imperiali FG, Cinquetti R, Vollero A, Terova G, Rimoldi S, Girardello R, Bossi E. Amino acid transporter B(0)AT1 (slc6a19) and ancillary protein: impact on function. Pflugers Arch 2016; 468:1363-74. [PMID: 27255547 DOI: 10.1007/s00424-016-1842-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/04/2016] [Accepted: 05/29/2016] [Indexed: 12/16/2022]
Abstract
Amino acids play an important role in the metabolism of all organisms. Their epithelial re-absorption is due to specific transport proteins, such as B(0)AT1, a Na(+)-coupled neutral amino acid symporter belonging to the solute carrier 6 family. Here, a recently cloned fish orthologue, from the intestine of Salmo salar, was electrophysiologically characterized with the two-electrode voltage clamp technique, in Xenopus laevis oocytes heterologously expressing the transporter. Substrate specificity, apparent affinities and the ionic dependence of the transport mechanism were determined in the presence of specific collectrin. Results demonstrated that like the human, but differently from sea bass (Dicentrarchus labrax) orthologue, salmon B(0)AT1 needs to be associated with partner proteins to be correctly expressed at the oocyte plasma membrane. Cloning of sea bass collectrin and comparison of membrane expression and functionality of the B(0)AT1 orthologue transporters allowed a deeper investigation on the role of their interactions. The parameters acquired by electrophysiological and immunolocalization experiments in the mammalian and fish transporters contributed to highlight the dynamic of relations and impacts on transport function of the ancillary proteins. The comparative characterization of the physiological parameters of amino acid transporters with auxiliary proteins can help the comprehension of the regulatory mechanism of essential nutrient absorption.
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Affiliation(s)
- Eleonora Margheritis
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Francesca Guia Imperiali
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Raffaella Cinquetti
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Alessandra Vollero
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Genciana Terova
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
- Interuniversity Center "The Protein Factory", Politecnico di Milano, ICRM-CNR Milano and Università dell'Insubria, Via Mancinelli 7, I-20131, Milan, Italy
| | - Simona Rimoldi
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Rossana Girardello
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy
| | - Elena Bossi
- Department of Biotechnology and Life Science, University of Insubria, Via J.H. Dunant 3, 21100, Varese, Italy.
- Interuniversity Center "The Protein Factory", Politecnico di Milano, ICRM-CNR Milano and Università dell'Insubria, Via Mancinelli 7, I-20131, Milan, Italy.
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