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Alarcón S, Garrido W, Vega G, Cappelli C, Suárez R, Oyarzún C, Quezada C, San Martín R. Deficient Insulin-mediated Upregulation of the Equilibrative Nucleoside Transporter 2 Contributes to Chronically Increased Adenosine in Diabetic Glomerulopathy. Sci Rep 2017; 7:9439. [PMID: 28842605 PMCID: PMC5572683 DOI: 10.1038/s41598-017-09783-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/28/2017] [Indexed: 12/21/2022] Open
Abstract
Deficient insulin signaling is a key event mediating diabetic glomerulopathy. Additionally, diabetic kidney disease has been related to increased levels of adenosine. Therefore, we tested a link between insulin deficiency and dysregulated activity of the equilibrative nucleoside transporters (ENTs) responsible for controlling extracellular levels of adenosine. In ex vivo glomeruli, high D-glucose decreased nucleoside uptake mediated by ENT1 and ENT2 transporters, resulting in augmented extracellular levels of adenosine. This condition was reversed by exposure to insulin. Particularly, insulin through insulin receptor/PI3K pathway markedly upregulated ENT2 uptake activity to restores the extracellular basal level of adenosine. Using primary cultured rat podocytes as a cellular model, we found insulin was able to increase ENT2 maximal velocity of transport. Also, PI3K activity was necessary to maintain ENT2 protein levels in the long term. In glomeruli of streptozotocin-induced diabetic rats, insulin deficiency leads to decreased activity of ENT2 and chronically increased extracellular levels of adenosine. Treatment of diabetic rats with adenosine deaminase attenuated both the glomerular loss of nephrin and proteinuria. In conclusion, we evidenced ENT2 as a target of insulin signaling and sensitive to dysregulation in diabetes, leading to chronically increased extracellular adenosine levels and thereby setting conditions conducive to kidney injury.
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Affiliation(s)
- Sebastián Alarcón
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Wallys Garrido
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Génesis Vega
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Claudio Cappelli
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Raibel Suárez
- 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
| | - Claudia Quezada
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Rody San Martín
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile.
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Oyarzún C, Garrido W, Alarcón S, Yáñez A, Sobrevia L, Quezada C, San Martín R. Adenosine contribution to normal renal physiology and chronic kidney disease. Mol Aspects Med 2017; 55:75-89. [PMID: 28109856 DOI: 10.1016/j.mam.2017.01.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 01/11/2017] [Accepted: 01/13/2017] [Indexed: 12/12/2022]
Abstract
Adenosine is a nucleoside that is particularly interesting to many scientific and clinical communities as it has important physiological and pathophysiological roles in the kidney. The distribution of adenosine receptors has only recently been elucidated; therefore it is likely that more biological roles of this nucleoside will be unveiled in the near future. Since the discovery of the involvement of adenosine in renal vasoconstriction and regulation of local renin production, further evidence has shown that adenosine signaling is also involved in the tubuloglomerular feedback mechanism, sodium reabsorption and the adaptive response to acute insults, such as ischemia. However, the most interesting finding was the increased adenosine levels in chronic kidney diseases such as diabetic nephropathy and also in non-diabetic animal models of renal fibrosis. When adenosine is chronically increased its signaling via the adenosine receptors may change, switching to a state that induces renal damage and produces phenotypic changes in resident cells. This review discusses the physiological and pathophysiological roles of adenosine and pays special attention to the mechanisms associated with switching homeostatic nucleoside levels to increased adenosine production in kidneys affected by CKD.
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Affiliation(s)
- Carlos Oyarzún
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Wallys Garrido
- 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
| | - Alejandro Yáñez
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Luis Sobrevia
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile; Department of Physiology, Faculty of Pharmacy, Universidad de Sevilla, Seville E-41012, Spain; University of Queensland Centre for Clinical Research (UQCCR), Faculty of Medicine and Biomedical Sciences, University of Queensland, Herston QLD 4029, Queensland, Australia
| | - Claudia Quezada
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Rody San Martín
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile.
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3
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Larijani B, Heshmat R, Ebrahimi-Rad M, Khatami S, Valadbeigi S, Saghiri R. Diagnostic Value of Adenosine Deaminase and Its Isoforms in Type II Diabetes Mellitus. Enzyme Res 2016; 2016:9526593. [PMID: 28050278 PMCID: PMC5165159 DOI: 10.1155/2016/9526593] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/14/2016] [Accepted: 11/01/2016] [Indexed: 11/29/2022] Open
Abstract
Background and Aims. In the present study, we have investigated the activity of adenosine deaminase (ADA) as a diagnostic marker in type 2 (or II) diabetes mellitus (T2DM). Design and Methods. The deaminase activity of ADA1 and ADA2 was determined in serum from 33 patients with type 2 (or II) diabetes mellitus and 35 healthy controls. We also determined the proportion of glycated hemoglobin (HbA1c). Results. Our results showed significant differences between total serum ADA (tADA) and ADA2 activities in the diabetic groups with HbA1c < 8 (%) and HbA1c ≥ 8 (%) with respect to the values in healthy individuals (p < 0.001). ADA2 activity in patients with high HbA1c was found to be much higher than that in patients with low HbA1c (p = 0.0001). In addition, total ADA activity showed a significant correlation with HbA1c (r = 0.6, p < 0.0001). Conclusions. Total serum ADA activity, specially that due to ADA2, could be useful test for the diagnosis of type 2 (or II) diabetes mellitus.
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Affiliation(s)
- Bagher Larijani
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Ramin Heshmat
- Chronic Diseases Research Center, Endocrinology and Metabolism Population Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Shohreh Khatami
- Department of Biochemistry, Pasteur Institute of Iran, Tehran, Iran
| | | | - Reza Saghiri
- Department of Biochemistry, Pasteur Institute of Iran, Tehran, Iran
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4
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Kretschmar C, Oyarzún C, Villablanca C, Jaramillo C, Alarcón S, Perez G, Díaz-Encarnación MM, Pastor-Anglada M, Garrido W, Quezada C, San Martín R. Reduced Adenosine Uptake and Its Contribution to Signaling that Mediates Profibrotic Activation in Renal Tubular Epithelial Cells: Implication in Diabetic Nephropathy. PLoS One 2016; 11:e0147430. [PMID: 26808537 PMCID: PMC4726618 DOI: 10.1371/journal.pone.0147430] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 01/03/2016] [Indexed: 11/18/2022] Open
Abstract
Altered nucleoside levels may be linked to pathogenic signaling through adenosine receptors. We hypothesized that adenosine dysregulation contributes to fibrosis in diabetic kidney disease. Our findings indicate that high glucose levels and experimental diabetes decreased uptake activity through the equilibrative nucleoside transporter 1 (ENT1) in proximal tubule cells. In addition, a correlation between increased plasma content of adenosine and a marker of renal fibrosis in diabetic rats was evidenced. At the cellular level, exposure of HK2 cells to high glucose, TGF-β and the general adenosine receptor agonist NECA, induced the expression of profibrotic cell activation markers α-SMA and fibronectin. These effects can be avoided by using a selective antagonist of the adenosine A3 receptor subtype in vitro. Furthermore, induction of fibrosis marker α-SMA was prevented by the A3 receptor antagonist in diabetic rat kidneys. In conclusion, we evidenced the contribution of purinergic signaling to renal fibrosis in experimental diabetic nephropathy.
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Affiliation(s)
- Catalina Kretschmar
- 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
| | - Cristopher Villablanca
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Catherinne Jaramillo
- 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
| | - Gustavo Perez
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | | | - Marçal Pastor-Anglada
- Institute of Biomedicine and Oncology Programme, National Biomedical Research Institute of Liver and Gastrointestinal Diseases (CIBER EHD), Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain
| | - Wallys Garrido
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Claudia Quezada
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Rody San Martín
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
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Sakowicz-Burkiewicz M, Grden M, Maciejewska I, Szutowicz A, Pawelczyk T. High glucose impairs ATP formation on the surface of human peripheral blood B lymphocytes. Int J Biochem Cell Biol 2013; 45:1246-54. [PMID: 23523697 DOI: 10.1016/j.biocel.2013.03.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/05/2013] [Accepted: 03/11/2013] [Indexed: 12/20/2022]
Abstract
Diabetes-associated lymphocyte dysfunction may be attributed to the direct effect of hyperglycemia, but the impact of glucose concentration on B cell functionality is not fully resolved. Since, adenosine 5'-triphosphate (ATP) and its metabolite adenosine are the core constituents of the purinergic signaling network involved in regulation of immune response we aimed to investigate the impact of high glucose concentration on ATP outflow and metabolism on B cell surface. Purified human peripheral blood B cells cultured at high glucose (25 mM) concentration released significantly less ATP (~60%) comparing to cells cultured in low glucose (5mM) concentration. We observed that high glucose altered ATP hydrolysis on B cell surface due to increased activity of nucleoside triphosphate diphosphohydrolase-1 (NTPDase-1/CD39). In the presence of 10 μM [(3)H]AMP and 100 μM ATP significant quantities of [(3)H]ADP and [(3)H]ATP were generated, although the AMP to ADP phosphorylation potential of B cells cultured in high glucose decreased significantly. The flow cytometry analysis revealed that the level of ecto-adenylate kinase 1β (AK1β) on surface of B cells cultured in high glucose decreased significantly. Inhibition of NTPDase1/CD39 activity with 100 μM ARL67156 resulted in decreased cell viability, although significantly more viable cells retained in the culture media containing low glucose compared to high glucose media. Selective inhibition of P2X7 purinergic receptor irrespective of glucose concentration completely protected B cells against the ARL 67156-induced cell death. We assume that high glucose-induced alteration of ATP handling on B cell surface might contribute to impaired functionality of B cells in diabetes.
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Abstract
Diabetic nephropathy ranks as the most devastating kidney disease worldwide. It characterizes in the early onset by glomerular hypertrophy, hyperfiltration and mesangial expansion. Experimental models show that overproduction of vascular endothelial growth factor (VEGF) is a pathogenic condition for podocytopathy; however the mechanisms that regulate this growth factor induction are not clearly identified. We determined that the adenosine A(2B) receptor (A(2B)AR) mediates VEGF overproduction in ex vivo glomeruli exposed to high glucose concentration, requiring PKCα and Erk1/2 activation. The glomerular content of A(2B)AR was concomitantly increased with VEGF at early stages of renal disease in streptozotocin-induced diabetic rats. Further, in vivo administration of an antagonist of A(2B)AR in diabetic rats blocked the glomerular overexpression of VEGF, mesangial cells activation and proteinuria. In addition, we also determined that the accumulation of extracellular adenosine occurs in glomeruli of diabetic rats. Correspondingly, raised urinary adenosine levels were found in diabetic rats. In conclusion, we evidenced that adenosine signaling at the onset of diabetic kidney disease is a pathogenic event that promotes VEGF induction.
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Abstract
Adenosine regulates the interaction between lymphocytes and the vasculature, and is important for controlling lymphocyte trafficking in response to tissue injury or infection. Adenosine can blunt the effects of T cell receptor activation primarily by activating adenosine A(2A) receptors and signaling via cyclic AMP and protein kinase A. Protein kinase A reduces proximal T cell receptor signaling by phosphorylation of C-terminal Src kinase, nuclear factor of activated T cells and cyclic AMP response element-binding protein. Protein kinase A activation can either enhance or inhibit the survival of T cells depending on the strength and duration of signaling. Inducible enzymes such as CD73 and CD39 regulate adenosine formation and degradation in vivo. The extravasation of lymphocytes through blood vessels is influenced by A(2A) receptors-mediated suppression of intercellular adhesion molecule 1 expression on lymphocytes and diminished production of interferon γ and interferon γ-inducible chemokines that are chemotactic to activated lymphocytes. Adenosine also decreases the barrier function of vascular endothelium by activating A(2B)Rs. In sum, adenosine signaling is influenced by tissue inflammation and injury through induction of receptors and enzymes and has generally inhibitory effects on lymphocyte migration into inflamed tissues due to protein kinase A-mediated effects on adhesion molecules, interferon γ production, and endothelial barrier function.
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Affiliation(s)
- Joel Linden
- Division of Inflammation Biology, La Jolla Institute of Allergy and Immunology, La Jolla, CA, USA.
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8
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Nucleoside transporters: biological insights and therapeutic applications. Future Med Chem 2012; 4:1461-78. [DOI: 10.4155/fmc.12.79] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Nucleoside transporters play important physiological roles by regulating intra- and extra-cellular concentrations of purine and pyrimidine (deoxy)nucleosides. This review describes the biological function and activity of the two major families of membrane nucleoside transporters that exist in mammalian cells. These include equilibrative nucleoside transporters that transport nucleosides in a gradient-dependent fashion and concentrative nucleoside transporters that import nucleosides against a gradient by coupling movement with sodium transport. Particular emphasis is placed on describing the roles of nucleoside transport in normal physiological processes, including inflammation, cardiovascular function and nutrient transport across the blood–brain barrier. In addition, the role of nucleoside transport in pathological conditions such as cardiovascular disease and cancer are discussed. The potential therapeutic applications of manipulating nucleoside transport activities are discussed, focusing on nucleoside analogs as anti-neoplastic agents. Finally, we discuss future directions for the development of novel chemical entities to measure nucleoside transport activity at the cellular and organismal level.
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Roa H, Gajardo C, Troncoso E, Fuentealba V, Escudero C, Yáñez A, Sobrevia L, Pastor-Anglada M, Quezada C, San Martin R. Adenosine mediates transforming growth factor-beta 1 release in kidney glomeruli of diabetic rats. FEBS Lett 2009; 583:3192-8. [PMID: 19737558 DOI: 10.1016/j.febslet.2009.09.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 08/18/2009] [Accepted: 09/02/2009] [Indexed: 01/13/2023]
Abstract
Up regulation of the transforming growth factor-beta 1 (TGF-beta1) axis has been recognized as a pathogenic event for progression of glomerulosclerosis in diabetic nephropathy. We demonstrate that glomeruli isolated from diabetic rats accumulate up to sixfold more extracellular adenosine than normal rats. Both decreased nucleoside uptake activity by the equilibrative nucleoside transporter 1 and increased AMP hydrolysis contribute to raise extracellular adenosine. Ex vivo assays indicate that activation of the low affinity adenosine A2B receptor subtype (A2BAR) mediates TGF-beta1 release from glomeruli of diabetic rats, a pathogenic event that could support progression of glomerulopathy when the bioavailability of adenosine is increased.
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Affiliation(s)
- H Roa
- Laboratorio Patología Molecular, Instituto de Bioquímica, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
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10
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Grden M, Podgorska M, Kocbuch K, Rzepko R, Szutowicz A, Pawelczyk T. High glucose suppresses expression of equilibrative nucleoside transporter 1 (ENT1) in rat cardiac fibroblasts through a mechanism dependent on PKC-zeta and MAP kinases. J Cell Physiol 2008; 215:151-60. [PMID: 17941087 DOI: 10.1002/jcp.21296] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Recently it was demonstrated that the elevated concentration of glucose but not lack of insulin is responsible for suppression of equilibrative nucleoside transporter (ENT1) in diabetic rat cardiac fibroblasts (CFs). The present study was undertaken to determine the signaling pathway utilized by glucose to regulate the expression of ENT1 in the primary culture of rat CFs. Pretreatment of CFs with Go 6983, an isozyme non-selective PKC inhibitor, prevented the high glucose (25 mM) effect on ENT1 mRNA level and nitrobenzylthioinosine (NBTI)-sensitive adenosine uptake. Similar effect was observed with a cell-permeable PKC-zeta pseudosubstrate, whereas Go 6976 a selective inhibitor of Ca(2+)-dependent PKC-alpha and PKC-beta isozymes had little effect on high glucose-induced suppression of ENT1 mRNA level. Incubation of CFs with nitric oxide (NO) donors (SNAPE, SNP) or NO synthase inhibitors (L-NAME, L-NMMA) prior to exposition of CFs to high glucose did not change the glucose effect on ENT1 mRNA level. The high glucose-induced suppression of ENT1 expression was blocked by PD9859 (an inhibitor of MEK), whereas neither wortmannin (an inhibitor of PI3K) nor rapamycin (an inhibitor of mTOR) affected the glucose action on ENT1 transcript level. Highly effective in preventing the high glucose effect on ENT1 mRNA level were GW 5074 (an inhibitor of Raf kinase) and SB 203580 (selective p38 MAPK inhibitor). These findings indicate that high glucose suppresses the expression of ENT1 in CFs by NO independent manner involving the signaling through PKC-zeta, Raf-1, MEK, and p38 MAPK pathways.
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Affiliation(s)
- Marzena Grden
- Department of Molecular Medicine, Medical University of Gdansk, Gdansk, Poland
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11
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Podgorska M, Kocbuch K, Grden M, Szulc A, Szutowicz A, Pawelczyk T. Different signaling pathways utilized by insulin to regulate the expression of ENT2, CNT1, CNT2 nucleoside transporters in rat cardiac fibroblasts. Arch Biochem Biophys 2007; 464:344-9. [PMID: 17537394 DOI: 10.1016/j.abb.2007.04.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 04/20/2007] [Accepted: 04/26/2007] [Indexed: 12/19/2022]
Abstract
In cardiac fibroblasts (CFs), insulin was shown to affect the expression of ENT2, CNT1, and CNT2 transporter. In the present study, we determined the signaling pathways utilized by insulin to regulate the expression of these nucleoside transporters. In the primary culture of rat CFs, insulin increased the mRNA level of ENT2 and suppressed the CNT1 and CNT2 mRNA levels. The insulin-induced increase of the ENT2 mRNA level was blocked by rapamycin (an inhibitor of mTOR) and by cycloheximide (an inhibitor of protein synthesis), whereas neither wortmannin (an inhibitor of PI3K) nor PD98059 (an inhibitor of MEK) affected the insulin action on the ENT2 transcript level. PD98059 completely blocked the insulin-induced decrease of the CNT1 and CNT2 mRNAs levels. Wortmannin prevented the insulin-induced change of the CNT1 mRNA level, but had no effect on the CNT2 mRNA. Rapamycin abolished the insulin effect on the CNT1 mRNA level, but not on the CNT2 mRNA. Cycloheximide prevented the insulin-induced decrease of CNT2 mRNA, but had no effect on the CNT1 mRNA level. Overall, our results demonstrate that the expression level of ENT2, CNT1, and CNT2 transporters in CFs is differentially regulated by insulin. Moreover, in this cell type insulin employs a distinct signaling pathway to regulate the expression of each transporter.
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Affiliation(s)
- Marzena Podgorska
- Department of Molecular Medicine, Medical University of Gdansk, ul. Debinki 7, paw. 29, 80-211 Gdansk, Poland
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12
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Muñoz G, San Martín R, Farías M, Cea L, Vecchiola A, Casanello P, Sobrevia L. Insulin restores glucose inhibition of adenosine transport by increasing the expression and activity of the equilibrative nucleoside transporter 2 in human umbilical vein endothelium. J Cell Physiol 2007; 209:826-35. [PMID: 16924660 DOI: 10.1002/jcp.20769] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
L-Arginine transport and nitric oxide (NO) synthesis (L-arginine/NO pathway) are stimulated by insulin, adenosine or elevated extracellular D-glucose in human umbilical vein endothelial cells (HUVEC). Adenosine uptake via the human equilibrative nucleoside transporters 1 (hENT1) and 2 (hENT2) has been proposed as a mechanism regulating adenosine plasma concentration, and therefore its vascular effects in human umbilical veins. Thus, altered expression and/or activity of hENT1 or hENT2 could lead to abnormal physiological plasma adenosine level. We have characterized insulin effect on adenosine transport in HUVEC cultured in normal (5 mM) or high (25 mM) D-glucose. Insulin (1 nM) increased overall adenosine transport associated with higher hENT2-, but lower hENT1-mediated transport in normal D-glucose. Insulin increased hENT2 protein abundance in normal or high D-glucose, but reduced hENT1 protein abundance in normal D-glucose. Insulin did not alter the reduced hENT1 protein abundance, but blocked the reduced hENT1 and hENT2 mRNA expression induced by high D-glucose. Insulin effect on hENT1 mRNA expression in normal D-glucose was blocked by N(G)-nitro-L-arginine methyl ester (L-NAME, NO synthase inhibitor) and mimicked by S-nitroso-N-acetyl-L,D-penicillamine (SNAP, NO donor). L-NAME did not block insulin effect on hENT2 expression. In conclusion, insulin stimulation of overall adenosine transport results from increased hENT2 expression and activity via a NO-independent mechanism. These findings could be important in hyperglycemia-associated pathological pregnancies, such as gestational diabetes, where plasma adenosine removal by the endothelium is reduced, a condition that could alter the blood flow from the placenta to the fetus affecting fetus growth and development.
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Affiliation(s)
- Gonzalo Muñoz
- Cellular and Molecular Physiology Laboratory (CMPL), Medical Research Centre (CIM), Department of Obstetrics and Gynaecology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
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13
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Sakowicz-Burkiewicz M, Kocbuch K, Grden M, Szutowicz A, Pawelczyk T. Diabetes-induced decrease of adenosine kinase expression impairs the proliferation potential of diabetic rat T lymphocytes. Immunology 2006; 118:402-12. [PMID: 16827901 PMCID: PMC1782307 DOI: 10.1111/j.1365-2567.2006.02380.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The proliferative response of T lymphocytes is a crucial step in cell-mediated immunity. This study was undertaken to investigate the mechanisms leading to the impaired proliferative response of diabetic T lymphocytes. T cells that had been isolated from the spleen of normal rats and cultured in medium containing 20 mm glucose and no insulin displayed the same degree of proliferative impairment as cells isolated from diabetic rats. The rate of T-cell proliferation, when induced with concanavalin A or anti-CD3 and anti-CD28 antibodies, was not affected by the inhibition of nucleoside transporters. T cells cultured at high glucose concentrations in the absence of insulin displayed decreased expression of adenosine kinase, and released measurable extracellular quantities of adenosine. Under resting conditions, the level of cAMP was 5.9-fold higher in these cells compared to cells grown in low glucose and in the presence of insulin. Experiments with specific adenosine receptor agonists and antagonists showed that adenosine-induced suppression of diabetic T cell proliferation was mediated by the A2A adenosine receptor, but not by the A2B receptor. Treatment of diabetic T cells with 10 microm H-89, a specific protein kinase A inhibitor, restored T-cell proliferation. These results show that suppressed proliferation of diabetic T lymphocytes is evoked by the decreased expression of adenosine kinase, leading to the outflow of adenosine from the cell. Extracellular adenosine then stimulates the A2A receptor and induces cAMP production, leading to the activation of protein kinase A, and suppression of T-cell proliferation.
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Affiliation(s)
| | - Katarzyna Kocbuch
- Department of Molecular Medicine, University of GdanskGdansk, Poland
| | - Marzena Grden
- Department of Molecular Medicine, University of GdanskGdansk, Poland
| | - Andrzej Szutowicz
- Department of Laboratory Medicine, University of GdanskGdansk, Poland
| | - Tadeusz Pawelczyk
- Department of Molecular Medicine, University of GdanskGdansk, Poland
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Pawelczyk T, Sakowicz-Burkiewicz M, Kocbuch K, Szutowicz A. Differential effect of insulin and elevated glucose level on adenosine handling in rat T lymphocytes. J Cell Biochem 2006; 96:1296-310. [PMID: 16173046 DOI: 10.1002/jcb.20642] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Reduced proliferation potential is among other T cell functional defects long known feature of diabetes. However, the mechanism responsible for this impairment is still unknown. Our study was undertaken to investigate the effect of changes in glucose and insulin concentrations on adenosine metabolism, transport and receptor-mediated action in rat T lymphocytes. Presented results indicate that vulnerability of T cells to metabolic stress is determined by insulin but not by glucose concentration. However, glucose and insulin differentially affected the activities of adenosine metabolizing enzymes in resting and proliferating T cells. The Con A-induced proliferation of cultured T lymphocytes did not depended on expression level and functional state of nucleoside transporters. Inhibition of adenosine kinase (AK) with 5-iodotubercidin lowers the proliferation potential of T cells to the level observed for insulin-deprived cells. Moreover, insulin-deprived T lymphocytes but not cells cultured in the presence of insulin released significant quantities of adenosine. Under resting conditions, the cAMP level was fivefold higher in cells deprived of insulin comparing to cells cultured in the presence of insulin. Exposition of insulin-deprived T lymphocytes to specific antagonist (ZM241385) of A2a receptor but not to specific antagonist (Alloxazine) of A2b receptor suppressed cAMP elevation and completely restored the proliferation potential of T cells. Concluding, adenosine released by insulin-deprived T cells due to suppressed AK activity by acting on A2a receptors leads to increases in cAMP level and suppression of T cell proliferation. We assume that this mechanism may significantly contribute to immune impairment observed in diabetes.
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Affiliation(s)
- Tadeusz Pawelczyk
- Department of Molecular Medicine, Medical University of Gdansk, 80-211 Gdansk, Poland.
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15
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Invited Lectures : Overviews Purinergic signalling: past, present and future. Purinergic Signal 2006; 2:1-324. [PMID: 18404494 PMCID: PMC2096525 DOI: 10.1007/s11302-006-9006-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/02/2006] [Indexed: 12/11/2022] Open
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