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Suarez R, Villarreal C, Nahuelpán Y, Jara C, Oyarzún C, Alarcón S, Díaz-Encarnación MM, Guillén-Gómez E, Quezada C, San Martín R. Defective insulin-stimulated equilibrative nucleoside transporter-2 activity and altered subcellular transporter distribution drive the loss of adenosine homeostasis in diabetic kidney disease progression. Biochim Biophys Acta Mol Basis Dis 2024; 1870:166890. [PMID: 37734469 DOI: 10.1016/j.bbadis.2023.166890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 08/23/2023] [Accepted: 09/16/2023] [Indexed: 09/23/2023]
Abstract
AIM Progression of diabetic nephropathy (DN) is linked to the dysregulated increase of adenosine and altered signaling properties. A major contribution to the maintenance of physiological extracellular adenosine levels relies on cellular uptake activity through plasma membrane nucleoside transporters. Because kidney cells are responsive to insulin, this study aims to determine how DN affects insulin regulation of the equilibrative nucleoside transporter-2 (ENT2). METHODS Human Podocytes and rat glomeruli were used to study ENT2 regulation. The effects of diabetes and insulin on ENT2 mediated transport activity were determined measuring the fraction of total adenosine uptake in sodium-free medium which is inhibitable by hypoxanthine. Alterations in ENT2 subcellular distribution were assessed in the kidney of people affected with DN and diabetic rats. The consequences of impaired ENT2 activity on the kidney were evaluated using dipyridamole in an animal model. RESULTS Insulin upregulates ENT2 uptake activity by increasing the Vmax, thus counteracting decreased adenosine uptake due to high d-glucose and achieving extracellular adenosine homeostasis. Insulin promoted ENT2 translocation to the plasma membrane dependent on PI3-kinase/Akt signaling and actin cytoskeleton integrity. However, in diabetic rats, the insulin-mediated induction of ENT2 activity was lost. Additionally, reduced Akt activation in response to insulin correlated with decreased ENT2 distribution at the plasma membrane. Kidney tissues from diabetic rats and human DN biopsies showed ENT2 redistribution to an intracellular pattern, evidencing dysfunctional adenosine uptake. Through ENT inhibition, we evidenced increased proteinuria and induced alpha-smooth muscle actin as a result of profibrotic activation of cells in the kidney. CONCLUSION Deficient insulin regulation of ENT2 activity contributes to chronically high adenosine levels and glomerular alterations that underline diabetic kidney disease progression.
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Affiliation(s)
- Raibel Suarez
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Carolina Villarreal
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Yessica Nahuelpán
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Claudia Jara
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Carlos Oyarzún
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Sebastián Alarcón
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Montserrat M Díaz-Encarnación
- Nephrology Service Fundació Puigvert, Biomedical Research Institute Sant Pau (IIB Sant Pau), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - Elena Guillén-Gómez
- Nephrology Service Fundació Puigvert, Biomedical Research Institute Sant Pau (IIB Sant Pau), Universitat Autònoma de Barcelona (UAB), Barcelona, Spain
| | - Claudia Quezada
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile; Millennium Institute on Immunology and Immunotherapy, Valdivia, Chile
| | - Rody San Martín
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile.
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Xiao C, Gavrilova O, Liu N, Lewicki SA, Reitman ML, Jacobson KA. In vivo phenotypic validation of adenosine receptor-dependent activity of non-adenosine drugs. Purinergic Signal 2023; 19:551-564. [PMID: 36781825 PMCID: PMC10539256 DOI: 10.1007/s11302-023-09924-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 01/31/2023] [Indexed: 02/15/2023] Open
Abstract
Some non-adenosinergic drugs are reported to also act through adenosine receptors (ARs). We used mouse hypothermia, which can be induced by agonism at any of the four ARs, as an in vivo screen for adenosinergic effects. An AR contribution was identified when a drug caused hypothermia in wild type mice that was diminished in mice lacking all four ARs (quadruple knockout, QKO). Alternatively, an adenosinergic effect was identified if a drug potentiated adenosine-induced hypothermia. Four drugs (dipyridamole, nimodipine, cilostazol, cyclosporin A) increased the hypothermia caused by adenosine. Dipyridamole and nimodipine probably achieved this by inhibition of adenosine clearance via ENT1. Two drugs (cannabidiol, canrenoate) did not cause hypothermia in wild type mice. Four other drugs (nifedipine, ranolazine, ketamine, ethanol) caused hypothermia, but the hypothermia was unchanged in QKO mice indicating non-adenosinergic mechanisms. Zinc chloride caused hypothermia and hypoactivity; the hypoactivity was blunted in the QKO mice. Interestingly, the antidepressant amitriptyline caused hypothermia in wild type mice that was amplified in the QKO mice. Thus, we have identified adenosine-related effects for some drugs, while other candidates do not affect adenosine signaling by this in vivo assay. The adenosine-modulating drugs could be considered for repurposing based on predicted effects on AR activation.
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Affiliation(s)
- Cuiying Xiao
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892-0810, USA
| | - Oksana Gavrilova
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892-0810, USA
| | - Naili Liu
- Mouse Metabolism Core, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892-0810, USA
| | - Sarah A Lewicki
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892-0810, USA
| | - Marc L Reitman
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892-0810, USA
| | - Kenneth A Jacobson
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892-0810, USA.
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O'Brien BJ, Faraoni EY, Strickland LN, Ma Z, Mota V, Mota S, Chen X, Mills T, Eltzschig HK, DelGiorno KE, Bailey‐Lundberg JM. CD73-generated extracellular adenosine promotes resolution of neutrophil-mediated tissue injury and restrains metaplasia in pancreatitis. FASEB J 2023; 37:e22684. [PMID: 36468677 PMCID: PMC9753971 DOI: 10.1096/fj.202201537r] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 11/07/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022]
Abstract
Pancreatitis is currently the leading cause of gastrointestinal hospitalizations in the US. This condition occurs in response to abdominal injury, gallstones, chronic alcohol consumption or, less frequently, the cause remains idiopathic. CD73 is a cell surface ecto-5'-nucleotidase that generates extracellular adenosine, which can contribute to resolution of inflammation by binding adenosine receptors on infiltrating immune cells. We hypothesized genetic deletion of CD73 would result in more severe pancreatitis due to decreased generation of extracellular adenosine. CD73 knockout (CD73-/- ) and C57BL/6 (wild type, WT) mice were used to evaluate the progression and response of caerulein-induced acute and chronic pancreatitis. In response to caerulein-mediated chronic or acute pancreatitis, WT mice display resolution of pancreatitis at earlier timepoints than CD73-/- mice. Using immunohistochemistry and analysis of single-cell RNA-seq (scRNA-seq) data, we determined CD73 localization in chronic pancreatitis is primarily observed in mucin/ductal cell populations and immune cells. In murine pancreata challenged with caerulein to induce acute pancreatitis, we compared CD73-/- to WT mice and observed a significant infiltration of Ly6G+, MPO+, and Granzyme B+ cells in CD73-/- compared to WT pancreata and we quantified a significant increase in acinar-to-ductal metaplasia demonstrating sustained metaplasia and inflammation in CD73-/- mice. Using neutrophil depletion in CD73-/- mice, we show neutrophil depletion significantly reduces metaplasia defined by CK19+ cells per field and significantly reduces acute pancreatitis. These data identify CD73 enhancers as a potential therapeutic strategy for patients with acute and chronic pancreatitis as adenosine generation and activation of adenosine receptors is critical to resolve persistent inflammation in the pancreas.
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Affiliation(s)
- Baylee J. O'Brien
- Center for Perioperative Medicine, Department of Anesthesiology, McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTexasUSA
| | - Erika Y. Faraoni
- Center for Perioperative Medicine, Department of Anesthesiology, McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTexasUSA
| | - Lincoln N. Strickland
- Center for Perioperative Medicine, Department of Anesthesiology, McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTexasUSA
| | - Zhibo Ma
- Gene Expression LaboratoryThe Salk Institute for Biological SciencesSan DiegoCaliforniaUSA
| | - Victoria Mota
- Center for Perioperative Medicine, Department of Anesthesiology, McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTexasUSA
| | - Samantha Mota
- Center for Perioperative Medicine, Department of Anesthesiology, McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTexasUSA
- The Graduate School of Biomedical SciencesThe University of Texas MD Anderson Cancer Center and The University of Texas Health Science Center at HoustonHoustonTexasUSA
| | - Xuebo Chen
- Center for Perioperative Medicine, Department of Anesthesiology, McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTexasUSA
| | - Tingting Mills
- Department of Biochemistry, McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTexasUSA
| | - Holger K. Eltzschig
- Center for Perioperative Medicine, Department of Anesthesiology, McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTexasUSA
| | - Kathleen E. DelGiorno
- Department of Cell and Developmental BiologyVanderbilt UniversityNashvilleTennesseeUSA
| | - Jennifer M. Bailey‐Lundberg
- Center for Perioperative Medicine, Department of Anesthesiology, McGovern Medical SchoolThe University of Texas Health Science Center at HoustonHoustonTexasUSA
- The Graduate School of Biomedical SciencesThe University of Texas MD Anderson Cancer Center and The University of Texas Health Science Center at HoustonHoustonTexasUSA
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Cladribine as a Potential Object of Nucleoside Transporter-Based Drug Interactions. Clin Pharmacokinet 2021; 61:167-187. [PMID: 34894346 PMCID: PMC8813788 DOI: 10.1007/s40262-021-01089-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2021] [Indexed: 12/15/2022]
Abstract
Cladribine is a nucleoside analog that is phosphorylated in its target cells (B and T-lymphocytes) to its active triphosphate form (2-chlorodeoxyadenosine triphosphate). Cladribine tablets 10 mg (Mavenclad®), administered for up to 10 days per year in 2 consecutive years (3.5-mg/kg cumulative dose over 2 years), are used to treat patients with relapsing multiple sclerosis. Cladribine has been shown to be a substrate of various nucleoside transporters (NTs). Intestinal absorption and distribution of cladribine throughout the body appear to be essentially mediated by equilibrative NTs (ENTs) and concentrative NTs (CNTs), specifically by ENT1, ENT2, ENT4, CNT2 (low affinity), and CNT3. Other efficient transporters of cladribine are the ABC efflux transporters, specifically breast cancer resistance protein, which likely modulates the oral absorption and renal excretion of cladribine. A key transporter for the intracellular uptake of cladribine into B and T-lymphocytes is ENT1 with ancillary contributions of ENT2 and CNT2. Transporter-based drug interactions affecting absorption and target cellular uptake of a prodrug such as cladribine are likely to reduce systemic bioavailability and target cell exposure, thereby possibly hampering clinical efficacy. In order to manage optimized therapy, i.e., to ensure uncompromised target cell uptake to preserve the full therapeutic potential of cladribine, it is important that clinicians are aware of the existence of NT-inhibiting medicinal products, various lifestyle drugs, and food components. This article reviews the existing knowledge on inhibitors of NT, which may alter cladribine absorption, distribution, and uptake into target cells, thereby summarizing the existing knowledge on optimized methods of administration and concomitant drugs that should be avoided during cladribine treatment.
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Maqsood N, Laslett DB, Patil A, Basil A, Gannon MP, Whitman IR. The Longer the Block, the Harder You Fall: Extrinsic Idiopathic Atrioventricular Block Masquerading as Seizures. JACC Case Rep 2021; 3:1086-1090. [PMID: 34317690 PMCID: PMC8311456 DOI: 10.1016/j.jaccas.2021.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 03/24/2021] [Accepted: 04/09/2021] [Indexed: 11/27/2022]
Abstract
History and physical examination are the diagnostic cornerstones of transient loss of consciousness (TLOC). However, details can be scarce and examination unrevealing, thus making the diagnosis elusive. In a case of convulsive TLOC, the initial diagnosis was incorrect, but a fortuitously captured event on telemetry yielded the diagnosis: extrinsic idiopathic atrioventricular block. (Level of Difficulty: Beginner.)
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Key Words
- AAI, single-chamber atrial pacing mode
- APL, plasma adenosine level
- AV, atrioventricular
- AVB, atrioventricular block
- DDD, dual-chamber pacing mode
- ECG, electrocardiogram
- EI-AVB, extrinsic idiopathic atrioventricular block
- ENT1, equilibrative nucleoside transporter 1
- EV-AVB, extrinsic vagal atrioventricular block
- I-AVB, intrinsic atrioventricular block
- MVP, Managed Ventricular Pacing
- PNES, psychogenic nonepileptic seizures
- TLOC, transient loss of consciousness
- convulsive syncope
- extrinsic idiopathic atrioventricular block
- paroxysmal atrioventricular block
- plasma adenosine levels
- transient loss of consciousness
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Affiliation(s)
- Naima Maqsood
- Department of Medicine, Lewis Katz School of Medicine at the Temple University Hospital, Philadelphia, Pennsylvania, USA
| | - David B Laslett
- Section of Cardiac Electrophysiology, Lewis Katz School of Medicine at the Temple University Hospital, Philadelphia, Pennsylvania, USA
| | - Aadhar Patil
- Temple Heart and Vascular Institute, Lewis Katz School of Medicine at the Temple University Hospital, Philadelphia, Pennsylvania, USA
| | - Anuj Basil
- Section of Cardiac Electrophysiology, Lewis Katz School of Medicine at the Temple University Hospital, Philadelphia, Pennsylvania, USA
| | - Michael P Gannon
- Temple Heart and Vascular Institute, Lewis Katz School of Medicine at the Temple University Hospital, Philadelphia, Pennsylvania, USA
| | - Isaac R Whitman
- Section of Cardiac Electrophysiology, Lewis Katz School of Medicine at the Temple University Hospital, Philadelphia, Pennsylvania, USA
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Abstract
Nucleosides play central roles in all facets of life, from metabolism to cellular signaling. Because of their physiochemical properties, nucleosides are lipid bilayer impermeable and thus rely on dedicated transport systems to cross biological membranes. In humans, two unrelated protein families mediate nucleoside membrane transport: the concentrative and equilibrative nucleoside transporter families. The objective of this review is to provide a broad outlook on the current status of nucleoside transport research. We will discuss the role played by nucleoside transporters in human health and disease, with emphasis placed on recent structural advancements that have revealed detailed molecular principles of these important cellular transport systems and exploitable pharmacological features.
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Affiliation(s)
- Nicholas J. Wright
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, North Carolina, 27710, USA
| | - Seok-Yong Lee
- Department of Biochemistry, Duke University Medical Center, 303 Research Drive, Durham, North Carolina, 27710, USA
- Correspondence and requests for materials should be addressed to: S.-Y. Lee., , tel: 919-684-1005, fax: 919-684-8885
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7
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Ma R, Fang H, Liu H, Pan L, Wang H, Zhang H. Overexpression of uracil permease and nucleoside transporter from Bacillus amyloliquefaciens improves cytidine production in Escherichia coli. Biotechnol Lett 2021; 43:1211-1219. [PMID: 33646457 DOI: 10.1007/s10529-021-03103-3] [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: 08/08/2020] [Accepted: 02/08/2021] [Indexed: 11/28/2022]
Abstract
Cytidine is an important raw material for nucleic acid health food and genetic engineering research. In recent years, it has shown irreplaceable effects in anti-virus, anti-tumor, and AIDS drugs. Its biosynthetic pathway is complex and highly regulated. In this study, overexpression of uracil permease and a nucleoside transporter from Bacillus amyloliquefaciens related to cell membrane transport in Escherichia coli strain BG-08 was found to increase cytidine production in shake flask cultivation by 1.3-fold (0.91 ± 0.03 g/L) and 1.8-fold (1.26 ± 0.03 g/L) relative to that of the original strain (0.70 ± 0.03 g/L), respectively. Co-overexpression of uracil permease and a nucleoside transporter further increased cytidine yield by 2.7-fold (1.59 ± 0.05 g/L) compared with that of the original strain. These results indicate that the overexpressed uracil permease and nucleoside transporter can promote the accumulation of cytidine, and the two proteins play a synergistic role in the secretion of cytidine in Escherichia coli.
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Affiliation(s)
- Ruoshuang Ma
- Ningxia Key Laboratory for Food Microbial-Applications Technology and Safety Control, School of Agriculture, Ningxia University, Yinchuan, 750021, China
| | - Haitian Fang
- Ningxia Key Laboratory for Food Microbial-Applications Technology and Safety Control, School of Agriculture, Ningxia University, Yinchuan, 750021, China
| | - Huiyan Liu
- Ningxia Key Laboratory for Food Microbial-Applications Technology and Safety Control, School of Agriculture, Ningxia University, Yinchuan, 750021, China.
| | - Lin Pan
- Ningxia Key Laboratory for Food Microbial-Applications Technology and Safety Control, School of Agriculture, Ningxia University, Yinchuan, 750021, China
| | - Hongyan Wang
- Ningxia Key Laboratory for Food Microbial-Applications Technology and Safety Control, School of Agriculture, Ningxia University, Yinchuan, 750021, China
| | - Heng Zhang
- Ningxia Key Laboratory for Food Microbial-Applications Technology and Safety Control, School of Agriculture, Ningxia University, Yinchuan, 750021, China
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Grañe-Boladeras N, Williams D, Tarmakova Z, Stevanovic K, Villani LA, Mehrabi P, Siu KWM, Pastor-Anglada M, Coe IR. Oligomerization of equilibrative nucleoside transporters: a novel regulatory and functional mechanism involving PKC and PP1. FASEB J 2018; 33:3841-3850. [PMID: 30521377 DOI: 10.1096/fj.201800440rr] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Equilibrative nucleoside transporters (ENTs) translocate nucleosides and nucleobases across plasma membranes, as well as a variety of anti-cancer, -viral, and -parasite nucleoside analogs. They are also key members of the purinome complex and regulate the protective and anti-inflammatory effects of adenosine. Despite their important role, little is known about the mechanisms involved in their regulation. We conducted membrane yeast 2-hybrid and coimmunoprecipitation studies and identified, for the first time to our knowledge, the existence of protein-protein interactions between human ENT1 and ENT2 (hENT1 and hENT2) proteins in human cells and the formation of hetero- and homo-oligomers at the plasma membrane and the submembrane region. The use of NanoLuc Binary Technology allowed us to analyze changes in the oligomeric status of hENT1 and hENT2 and how they rapidly modify the uptake profile for nucleosides and nucleobases and allow cells to respond promptly to external signals or changes in the extracellular environment. These changes in hENTs oligomerization are triggered by PKC activation and subsequent action of protein phosphatase 1.-Grañe-Boladeras, N., Williams, D., Tarmakova, Z., Stevanovic, K., Villani, L. A., Mehrabi, P., Siu, K. W. M., Pastor-Anglada, M., Coe, I. R. Oligomerization of equilibrative nucleoside transporters: a novel regulatory and functional mechanism involving PKC and PP1.
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Affiliation(s)
- Natalia Grañe-Boladeras
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine, University of Barcelona, Barcelona, Spain.,National Biomedical Research Institute of Liver and Gastrointestinal Diseases, Barcelona, Spain
| | - Declan Williams
- Department of Chemistry, York University, Toronto, Ontario, Canada; and
| | - Zlatina Tarmakova
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Katarina Stevanovic
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Linda A Villani
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Pedram Mehrabi
- Department of Biology, York University, Toronto, Ontario, Canada
| | - K W Michael Siu
- Department of Chemistry, York University, Toronto, Ontario, Canada; and
| | - Marçal Pastor-Anglada
- Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine, University of Barcelona, Barcelona, Spain.,National Biomedical Research Institute of Liver and Gastrointestinal Diseases, Barcelona, Spain
| | - Imogen R Coe
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
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Pastor-Anglada M, Pérez-Torras S. Emerging Roles of Nucleoside Transporters. Front Pharmacol 2018; 9:606. [PMID: 29928232 PMCID: PMC5997781 DOI: 10.3389/fphar.2018.00606] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/21/2018] [Indexed: 01/02/2023] Open
Abstract
Since human Nucleoside Transporters (hNTs) were identified by their activity as transport systems, extensive work has been done to fully characterize them at the molecular and physiological level. Many efforts have been addressed to the identification of their selectivity for natural substrates and nucleoside analogs used to treat several diseases. hNTs belong to two different gene families, SLC28 and SLC29, encoding human Concentrative Nucleoside Transporters (hCNTs) and human Equilibrative Nucleoside Transporters (hENTs), respectively. hCNTs and hENTs are integral membrane proteins, albeit structurally unrelated. Both families share common features as substrate selectivity and often tissue localization. This apparent biological redundancy may anticipate some different roles for hCNTs and hENTs in cell physiology. Thus, hENTs may have a major role in maintaining nucleoside homeostasis, whereas hCNTs could contribute to nucleoside sensing and signal transduction. In this sense, the ascription of hCNT1 to a transceptor reinforces this hypothesis. Moreover, some evidences could suggest a putative role of hCNT2 and hCNT3 as transceptors. The interacting proteins identified for hCNT2 suggest a link to energy metabolism. Moreover, the ability of hCNT2 and hCNT3 to transport adenosine links both proteins to purinergic signaling. On the other hand, the broad selectivity transporters hENTs have a crucial role in salvage pathways and purinergic signaling by means of nucleoside pools regulation. In particular, the two new hENT2 isoforms recently described together with hENT2 seem to be key elements controlling nucleoside and nucleotide pools for DNA synthesis. This review focuses on all these NTs functions beyond their mere translocation ability.
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Affiliation(s)
- Marçal Pastor-Anglada
- Biochemistry and Molecular Pharmacology Section, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
| | - Sandra Pérez-Torras
- Biochemistry and Molecular Pharmacology Section, Department of Biochemistry and Molecular Biomedicine, Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain
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10
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Functional Characterization of the Saccharomyces cerevisiae Equilibrative Nucleoside Transporter 1 (ScENT1). Molecules 2018; 23:molecules23040732. [PMID: 29565807 PMCID: PMC6017673 DOI: 10.3390/molecules23040732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 03/07/2018] [Accepted: 03/14/2018] [Indexed: 02/06/2023] Open
Abstract
Equilibrative nucleoside transporters (ENTs) are polytopic membrane transporters responsible for the translocation of nucleosides, nucleobases—to a lesser extent—and nucleoside analog therapeutics across cellular membranes. ENTs function in a diffusion controlled bidirectional manner and are thought to utilize an alternating access transport mechanism. However, a detailed understanding of ENT function at the molecular level has remained elusive. ScENT1 (formerly known as Function Unknown Now 26 or FUN26) is the only known ENT ortholog endogenously expressed in S. cerevisiae, and a proteoliposome assay system was used to study homogenously overexpressed and purified ScENT1 (wildtype relative to L390A and F249I mutants). L390 and F249 are highly conserved residues and were found to alter transporter function. L390A produced a reduction of mean transport activity while F249I increased mean substrate translocation relative to wildtype protein. However, both mutations resulted in transport of UTP—a novel gain of function for any ENT. These residues were then mapped onto an ab initio model of FUN26 which suggests they function in substrate translocation (L390) or cytoplasmic gating (F249). Furthermore, wildtype, L390A, and F249I were found to be sensitive to the presence of alcohols. Ethanol attenuated ScENT1-mediated transport of uridine by ~50%. These findings further demonstrate functional similarities between ScENT1 and human ENT isoforms and support identification of FUN26 as ScENT1, the first ENT isoform in S. cerevisiae.
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11
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Oliveros A, Starski P, Lindberg D, Choi S, Heppelmann CJ, Dasari S, Choi DS. Label-Free Neuroproteomics of the Hippocampal-Accumbal Circuit Reveals Deficits in Neurotransmitter and Neuropeptide Signaling in Mice Lacking Ethanol-Sensitive Adenosine Transporter. J Proteome Res 2017; 16:1445-1459. [PMID: 27998058 DOI: 10.1021/acs.jproteome.6b00830] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The neural circuit of the dorsal hippocampus (dHip) and nucleus accumbens (NAc) contributes to cue-induced learning and addictive behaviors, as demonstrated by the escalation of ethanol-seeking behaviors observed following deletion of the adenosine equilibrative nucleoside transporter 1 (ENT1-/-) in mice. Here we perform quantitative LC-MS/MS neuroproteomics in the dHip and NAc of ENT1-/- mice. Using Ingenuity Pathway Analysis, we identified proteins associated with increased long-term potentiation, ARP2/3-mediated actin cytoskeleton signaling and protein expression patterns suggesting deficits in glutamate degradation, GABAergic signaling, as well as significant changes in bioenergetics and energy homeostasis (oxidative phosphorylation, TCA cycle, and glycolysis). These pathways are consistent with previously reported behavioral and biochemical phenotypes that typify mice lacking ENT1. Moreover, we validated decreased expression of the SNARE complex protein VAMP1 (synaptobrevin-1) in the dHip as well as decreased expression of pro-dynorphin (PDYN), neuroendocrine convertase (PCSK1), and Leu-Enkephalin (dynorphin-A) in the NAc. Taken together, our proteomic approach provides novel pathways indicating that ENT1-regulated signaling is essential for neurotransmitter release and neuropeptide processing, both of which underlie learning and reward-seeking behaviors.
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Affiliation(s)
- Alfredo Oliveros
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Phillip Starski
- Neurobiology of Disease Program, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Daniel Lindberg
- Neurobiology of Disease Program, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Sun Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Carrie J Heppelmann
- Proteomics Research Center, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Surendra Dasari
- Division of Biomedical Statistics and Informatics, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Rochester, Minnesota 55905, United States.,Neurobiology of Disease Program, Mayo Clinic , Rochester, Minnesota 55905, United States.,Department of Psychiatry and Psychology, Mayo Clinic , Rochester, Minnesota 55905, United States
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Boswell-Casteel RC, Hays FA. Equilibrative nucleoside transporters-A review. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2016; 36:7-30. [PMID: 27759477 DOI: 10.1080/15257770.2016.1210805] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Equilibrative nucleoside transporters (ENTs) are polytopic integral membrane proteins that mediate the transport of nucleosides, nucleobases, and therapeutic analogs. The best-characterized ENTs are the human transporters hENT1 and hENT2. However, non-mammalian eukaryotic ENTs have also been studied (e.g., yeast, parasitic protozoa). ENTs are major pharmaceutical targets responsible for modulating the efficacy of more than 30 approved drugs. However, the molecular mechanisms and chemical determinants of ENT-mediated substrate recognition, binding, inhibition, and transport are poorly understood. This review highlights findings on the characterization of ENTs by surveying studies on genetics, permeant and inhibitor interactions, mutagenesis, and structural models of ENT function.
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Affiliation(s)
- Rebba C Boswell-Casteel
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Franklin A Hays
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA.,b Stephenson Cancer Center , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA.,c Harold Hamm Diabetes Center , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
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Bicket A, Mehrabi P, Naydenova Z, Wong V, Donaldson L, Stagljar I, Coe IR. Novel regulation of equlibrative nucleoside transporter 1 (ENT1) by receptor-stimulated Ca2+-dependent calmodulin binding. Am J Physiol Cell Physiol 2016; 310:C808-20. [PMID: 27009875 DOI: 10.1152/ajpcell.00243.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 03/09/2016] [Indexed: 01/25/2023]
Abstract
Equilibrative nucleoside transporters (ENTs) facilitate the flux of nucleosides, such as adenosine, and nucleoside analog (NA) drugs across cell membranes. A correlation between adenosine flux and calcium-dependent signaling has been previously reported; however, the mechanistic basis of these observations is not known. Here we report the identification of the calcium signaling transducer calmodulin (CaM) as an ENT1-interacting protein, via a conserved classic 1-5-10 motif in ENT1. Calcium-dependent human ENT1-CaM protein interactions were confirmed in human cell lines (HEK293, RT4, U-87 MG) using biochemical assays (HEK293) and the functional assays (HEK293, RT4), which confirmed modified nucleoside uptake that occurred in the presence of pharmacological manipulations of calcium levels and CaM function. Nucleoside and NA drug uptake was significantly decreased (∼12% and ∼39%, respectively) by chelating calcium (EGTA, 50 μM; BAPTA-AM, 25 μM), whereas increasing intracellular calcium (thapsigargin, 1.5 μM) led to increased nucleoside uptake (∼26%). Activation of N-methyl-d-aspartate (NMDA) receptors (in U-87 MG) by glutamate (1 mM) and glycine (100 μM) significantly increased nucleoside uptake (∼38%) except in the presence of the NMDA receptor antagonist, MK-801 (50 μM), or CaM antagonist, W7 (50 μM). These data support the existence of a previously unidentified novel receptor-dependent regulatory mechanism, whereby intracellular calcium modulates nucleoside and NA drug uptake via CaM-dependent interaction of ENT1. These findings suggest that ENT1 is regulated via receptor-dependent calcium-linked pathways resulting in an alteration of purine flux, which may modulate purinergic signaling and influence NA drug efficacy.
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Affiliation(s)
- Alex Bicket
- Department of Biology, York University, Toronto, Canada
| | - Pedram Mehrabi
- Department of Biology, York University, Toronto, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Zlatina Naydenova
- Department of Chemistry and Biology, Ryerson University, Toronto, Canada
| | - Victoria Wong
- Donnelly Centre, Department of Biochemistry and Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | | | - Igor Stagljar
- Donnelly Centre, Department of Biochemistry and Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Imogen R Coe
- Department of Biology, York University, Toronto, Canada; Department of Chemistry and Biology, Ryerson University, Toronto, Canada;
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