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Bankir L, Crambert G, Vargas-Poussou R. The SLC6A18 Transporter Is Most Likely a Na-Dependent Glycine/Urea Antiporter Responsible for Urea Secretion in the Proximal Straight Tubule: Influence of This Urea Secretion on Glomerular Filtration Rate. Nephron Clin Pract 2024:1-27. [PMID: 38824912 DOI: 10.1159/000539602] [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: 02/13/2024] [Accepted: 05/25/2024] [Indexed: 06/04/2024] Open
Abstract
BACKGROUND Urea is the major end-product of protein metabolism in mammals. In carnivores and omnivores, a large load of urea is excreted daily in urine, with a concentration that is 30-100 times above that in plasma. This is important for the sake of water economy. Too little attention has been given to the existence of energy-dependent urea transport that plays an important role in this concentrating activity. SUMMARY This review first presents functional evidence for an energy-dependent urea secretion that occurs exclusively in the straight part of the proximal tubule (PST). Second, it proposes a candidate transmembrane transporter responsible for this urea secretion in the PST. SLC6A18 is expressed exclusively in the PST and has been identified as a glycine transporter, based on findings in SLC6A18 knockout mice. We propose that it is actually a glycine/urea antiport, secreting urea into the lumen in exchange for glycine and Na. Glycine is most likely recycled back into the cell via a transporter located in the brush border. Urea secretion in the PST modifies the composition of the tubular fluid in the thick ascending limb and, thus, contributes, indirectly, to influence the "signal" at the macula densa that plays a crucial role in the regulation of the glomerular filtration rate (GFR) by the tubulo-glomerular feedback. KEY MESSAGES Taking into account this secondary active secretion of urea in the mammalian kidney provides a new understanding of the influence of protein intake on GFR, of the regulation of urea excretion, and of the urine-concentrating mechanism.
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Affiliation(s)
- Lise Bankir
- Laboratoire de Physiologie Rénale et Tubulopathies, Centre de Recherche des Cordeliers, INSERM UMRS 1138, Sorbonne Université, Université Paris Cité, Paris, France
- CNRS EMR 8228, Unité Métabolisme et Physiologie Rénale, Centre de Recherche des Cordeliers, Paris, France
| | - Gilles Crambert
- Laboratoire de Physiologie Rénale et Tubulopathies, Centre de Recherche des Cordeliers, INSERM UMRS 1138, Sorbonne Université, Université Paris Cité, Paris, France
- CNRS EMR 8228, Unité Métabolisme et Physiologie Rénale, Centre de Recherche des Cordeliers, Paris, France
| | - Rosa Vargas-Poussou
- CNRS EMR 8228, Unité Métabolisme et Physiologie Rénale, Centre de Recherche des Cordeliers, Paris, France
- Service de Médecine Génomique des Maladies Rares, Assistance Publique-Hôpitaux de Paris, Université Paris Cité, Paris, France
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte, MARHEA, Hôpital Européen Georges Pompidou, Paris, France
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2
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Chambers BE, Weaver NE, Lara CM, Nguyen TK, Wingert RA. (Zebra)fishing for nephrogenesis genes. Tissue Barriers 2024; 12:2219605. [PMID: 37254823 PMCID: PMC11042071 DOI: 10.1080/21688370.2023.2219605] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 05/14/2023] [Indexed: 06/01/2023] Open
Abstract
Kidney disease is a devastating condition affecting millions of people worldwide, where over 100,000 patients in the United States alone remain waiting for a lifesaving organ transplant. Concomitant with a surge in personalized medicine, single-gene mutations, and polygenic risk alleles have been brought to the forefront as core causes of a spectrum of renal disorders. With the increasing prevalence of kidney disease, it is imperative to make substantial strides in the field of kidney genetics. Nephrons, the core functional units of the kidney, are epithelial tubules that act as gatekeepers of body homeostasis by absorbing and secreting ions, water, and small molecules to filter the blood. Each nephron contains a series of proximal and distal segments with explicit metabolic functions. The embryonic zebrafish provides an ideal platform to systematically dissect the genetic cues governing kidney development. Here, we review the use of zebrafish to discover nephrogenesis genes.
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Affiliation(s)
- Brooke E. Chambers
- Department of Biological Sciences, Center for Stem Cells and Regenerative Medicine, Center for Zebrafish Research, Boler-Parseghian Center for Rare and Neglected Diseases, Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, Indiana (IN), USA
| | - Nicole E. Weaver
- Department of Biological Sciences, Center for Stem Cells and Regenerative Medicine, Center for Zebrafish Research, Boler-Parseghian Center for Rare and Neglected Diseases, Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, Indiana (IN), USA
| | - Caroline M. Lara
- Department of Biological Sciences, Center for Stem Cells and Regenerative Medicine, Center for Zebrafish Research, Boler-Parseghian Center for Rare and Neglected Diseases, Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, Indiana (IN), USA
| | - Thanh Khoa Nguyen
- Department of Biological Sciences, Center for Stem Cells and Regenerative Medicine, Center for Zebrafish Research, Boler-Parseghian Center for Rare and Neglected Diseases, Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, Indiana (IN), USA
| | - Rebecca A. Wingert
- Department of Biological Sciences, Center for Stem Cells and Regenerative Medicine, Center for Zebrafish Research, Boler-Parseghian Center for Rare and Neglected Diseases, Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, Indiana (IN), USA
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3
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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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4
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Hall SM, Raines NH, Ramirez-Rubio O, Amador JJ, López-Pilarte D, O'Callaghan-Gordo C, Gil-Redondo R, Embade N, Millet O, Peng X, Vences S, Keogh SA, Delgado IS, Friedman DJ, Brooks DR, Leibler JH. Urinary Metabolomic Profile of Youth at Risk of Chronic Kidney Disease in Nicaragua. KIDNEY360 2023; 4:899-908. [PMID: 37068179 PMCID: PMC10371259 DOI: 10.34067/kid.0000000000000129] [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: 10/26/2022] [Accepted: 03/22/2023] [Indexed: 04/19/2023]
Abstract
Key Points Urinary concentrations of glycine, a molecule associated with thermoregulation, were elevated among youth from a high-risk region for chronic kidney disease of non-traditional etiology (CKDnt). Urinary concentrations of pyruvate, citric acid, and inosine were lower among youth at higher risk of CKDnt, suggesting renal stress. Metabolomic analyses may shed light on early disease processes or profiles or risk in the context of CKDnt. Background CKD of a nontraditional etiology (CKDnt) is responsible for high mortality in Central America, although its causes remain unclear. Evidence of kidney dysfunction has been observed among youth, suggesting that early kidney damage contributing to CKDnt may initiate in childhood. Methods Urine specimens of young Nicaraguan participants 12–23 years without CKDnt (n =136) were analyzed by proton nuclear magnetic resonance spectroscopy for 50 metabolites associated with kidney dysfunction. Urinary metabolite levels were compared by, regional CKDnt prevalence, sex, age, and family history of CKDnt using supervised statistical methods and pathway analysis in MetaboAnalyst. Magnitude of associations and changes over time were assessed through multivariable linear regression. Results In adjusted analyses, glycine concentrations were higher among youth from high-risk regions (β =0.82, [95% confidence interval, 0.16 to 1.85]; P = 0.01). Pyruvate concentrations were lower among youth with low eGFR (β = −0.36 [95% confidence interval, −0.57 to −0.04]; P = 0.03), and concentrations of other citric acid cycle metabolites differed by key risk factors. Over four years, participants with low eGFR experienced greater declines in 1-methylnicotinamide and 2-oxoglutarate and greater increases in citrate and guanidinoacetate concentrations. Conclusion Urinary concentration of glycine, a molecule associated with thermoregulation and kidney function preservation, was higher among youth in high-risk CKDnt regions, suggestive of greater heat exposure or renal stress. Lower pyruvate concentrations were associated with low eGFR, and citric acid cycle metabolites, such as pyruvate, likely relate to mitochondrial respiration rates in the kidneys. Participants with low eGFR experienced longitudinal declines in concentrations of 1-methylnicotinamide, an anti-inflammatory metabolite associated with anti-fibrosis in tubule cells. These findings merit further consideration in research on the origins of CKDnt.
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Affiliation(s)
- Samantha M. Hall
- Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts
| | - Nathan H. Raines
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Oriana Ramirez-Rubio
- Barcelona Institute for Global Health, ISGlobal, Barcelona, Spain
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts
| | - Juan José Amador
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts
| | - Damaris López-Pilarte
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts
| | - Cristina O'Callaghan-Gordo
- Barcelona Institute for Global Health, ISGlobal, Barcelona, Spain
- Faculty of Health Sciences, Universitat Oberta de Catalunya, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Rubén Gil-Redondo
- Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Bizkaia, Spain
| | - Nieves Embade
- Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Bizkaia, Spain
| | - Oscar Millet
- Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Bizkaia, Spain
- CIBERehd, Instituto de Salud Carlos III, Madrid, Spain
| | - Xiaojing Peng
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts
| | - Selene Vences
- Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts
| | - Sinead A. Keogh
- Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts
| | - Iris S. Delgado
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts
| | - David J. Friedman
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Daniel R. Brooks
- Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts
| | - Jessica H. Leibler
- Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts
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Osman W, Mousa M, Albreiki M, Baalfaqih Z, Daggag H, Hill C, McKnight AJ, Maxwell AP, Al Safar H. A genome-wide association study identifies a possible role for cannabinoid signalling in the pathogenesis of diabetic kidney disease. Sci Rep 2023; 13:4661. [PMID: 36949158 PMCID: PMC10033677 DOI: 10.1038/s41598-023-31701-w] [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: 01/11/2023] [Accepted: 03/16/2023] [Indexed: 03/24/2023] Open
Abstract
Diabetic kidney disease (DKD), also known as diabetic nephropathy, is the leading cause of renal impairment and end-stage renal disease. Patients with diabetes are at risk for DKD because of poor control of their blood glucose, as well as nonmodifiable risk factors including age, ethnicity, and genetics. This genome-wide association study (GWAS) was conducted for the first time in the Emirati population to investigate possible genetic factors associated with the development and progression of DKD. We included data on 7,921,925 single nucleotide polymorphism (SNPs) in 258 cases of type 2 diabetes mellitus (T2DM) who developed DKD and 938 control subjects with T2DM who did not develop DKD. GWAS suggestive results (P < 1 × 10-5) were further replicated using summary statistics from three cohorts with T2DM-induced DKD (Bio Bank Japan data, UK Biobank, and FinnGen Project data) and T1DM-induced DKD (UK-ROI cohort data from Belfast, UK). When conducting a multiple linear regression model for gene-set analyses, the CNR2 gene demonstrated genome-wide significance at 1.46 × 10-6. SNPs in CNR2 gene, encodes cannabinoid receptor 2 or CB2, were replicated in Japanese samples with the leading SNP rs2501391 showing a Pcombined = 9.3 × 10-7, and odds ratio = 0.67 in association with DKD associated with T2DM, but not with T1DM, without any significant association with T2DM itself. The allele frequencies of our cohort and those of the replication cohorts were in most cases markedly different. In addition, we replicated the association between rs1564939 in the GLRA3 gene and DKD in T2DM (P = 0.016, odds ratio = 0.54 per allele C). Our findings suggest evidence that cannabinoid signalling may be involved in the development of DKD through CB2, which is expressed in different kidney regions and known to be involved in insulin resistance, inflammation, and the development of kidney fibrosis.
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Affiliation(s)
- Wael Osman
- Center for Biotechnology, Khalifa University, PO Box 127788, Abu Dhabi, United Arab Emirates
- Department of Biology, College of Arts and Sciences, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Mira Mousa
- Center for Biotechnology, Khalifa University, PO Box 127788, Abu Dhabi, United Arab Emirates
| | - Mohammed Albreiki
- Center for Biotechnology, Khalifa University, PO Box 127788, Abu Dhabi, United Arab Emirates
| | - Zahrah Baalfaqih
- Center for Biotechnology, Khalifa University, PO Box 127788, Abu Dhabi, United Arab Emirates
| | - Hinda Daggag
- Imperial College of London Diabetes Centre, Abu Dhabi, United Arab Emirates
| | - Claire Hill
- Centre for Public Health, Queen's University of Belfast, Belfast, UK
| | | | | | - Habiba Al Safar
- Center for Biotechnology, Khalifa University, PO Box 127788, Abu Dhabi, United Arab Emirates.
- Department of Biomedical Engineering, College of Engineering, Khalifa University, Abu Dhabi, United Arab Emirates.
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6
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Weaver NE, Healy A, Wingert RA. gldc Is Essential for Renal Progenitor Patterning during Kidney Development. Biomedicines 2022; 10:biomedicines10123220. [PMID: 36551976 PMCID: PMC9776136 DOI: 10.3390/biomedicines10123220] [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: 11/05/2022] [Revised: 12/04/2022] [Accepted: 12/07/2022] [Indexed: 12/14/2022] Open
Abstract
The glycine cleavage system (GCS) is a complex located on the mitochondrial membrane that is responsible for regulating glycine levels and contributing one-carbon units to folate metabolism. Congenital mutations in GCS components, such as glycine decarboxylase (gldc), cause an elevation in glycine levels and the rare disease, nonketotic hyperglycinemia (NKH). NKH patients suffer from pleiotropic symptoms including seizures, lethargy, mental retardation, and early death. Therefore, it is imperative to fully elucidate the pathological effects of gldc dysfunction and glycine accumulation during development. Here, we describe a zebrafish model of gldc deficiency that recapitulates phenotypes seen in humans and mice. gldc deficient embryos displayed impaired fluid homeostasis suggesting renal abnormalities, as well as aberrant craniofacial morphology and neural development defects. Whole mount in situ hybridization (WISH) revealed that gldc transcripts were highly expressed in the embryonic kidney, as seen in mouse and human repository data, and that formation of several nephron segments was disrupted in gldc deficient embryos, including proximal and distal tubule populations. These kidney defects were caused by alterations in renal progenitor populations, revealing that the proper function of Gldc is essential for the patterning of this organ. Additionally, further analysis of the urogenital tract revealed altered collecting duct and cloaca morphology in gldc deficient embryos. Finally, to gain insight into the molecular mechanisms underlying these disruptions, we examined the effects of exogenous glycine treatment and observed analogous renal and cloacal defects. Taken together, these studies indicate for the first time that gldc function serves an essential role in regulating renal progenitor development by modulating glycine levels.
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7
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Sandholm N, Haukka JK, Toppila I, Valo E, Harjutsalo V, Forsblom C, Groop PH. Confirmation of GLRA3 as a susceptibility locus for albuminuria in Finnish patients with type 1 diabetes. Sci Rep 2018; 8:12408. [PMID: 30120300 PMCID: PMC6098108 DOI: 10.1038/s41598-018-29211-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 06/12/2018] [Indexed: 02/06/2023] Open
Abstract
Urinary albumin excretion is an early sign of diabetic kidney disease, affecting every third individual with diabetes. Despite substantial estimated heritability, only variants in the GLRA3 gene have been genome-wide significantly associated (p-value < 5 × 10−8) with diabetic albuminuria, in Finnish individuals with type 1 diabetes; However, replication attempt in non-Finnish Europeans with type 1 diabetes showed nominally significant association in the opposite direction, suggesting a population-specific effect, but simultaneously leaving the finding controversial. In this study, the association between the common rs10011025 variant in the GLRA3 locus, and albuminuria, was confirmed in 1259 independent Finnish individuals with type 1 diabetes (p = 0.0013), and meta-analysis of all Finnish individuals yielded a genome-wide significant association. The association was particularly pronounced in subjects not reaching the treatment target for blood glucose levels (HbA1c > 7%; N = 2560, p = 1.7 × 10−9). Even though further studies are needed to pinpoint the causal variants, dissecting the association at the GLRA3 locus may uncover novel molecular mechanisms for diabetic albuminuria irrespective of population background.
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Affiliation(s)
- Niina Sandholm
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, FI-00290, Helsinki, Finland.,Abdominal Center, Nephrology, University of Helsinki and Helsinki University Hospital, FI-00290, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, FI-00290, Helsinki, Finland
| | - Jani K Haukka
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, FI-00290, Helsinki, Finland.,Abdominal Center, Nephrology, University of Helsinki and Helsinki University Hospital, FI-00290, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, FI-00290, Helsinki, Finland
| | - Iiro Toppila
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, FI-00290, Helsinki, Finland.,Abdominal Center, Nephrology, University of Helsinki and Helsinki University Hospital, FI-00290, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, FI-00290, Helsinki, Finland
| | - Erkka Valo
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, FI-00290, Helsinki, Finland.,Abdominal Center, Nephrology, University of Helsinki and Helsinki University Hospital, FI-00290, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, FI-00290, Helsinki, Finland
| | - Valma Harjutsalo
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, FI-00290, Helsinki, Finland.,Abdominal Center, Nephrology, University of Helsinki and Helsinki University Hospital, FI-00290, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, FI-00290, Helsinki, Finland.,The Chronic Disease Prevention Unit, National Institute for Health and Welfare, FI-00271, Helsinki, Finland
| | - Carol Forsblom
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, FI-00290, Helsinki, Finland.,Abdominal Center, Nephrology, University of Helsinki and Helsinki University Hospital, FI-00290, Helsinki, Finland.,Research Programs Unit, Diabetes and Obesity, University of Helsinki, FI-00290, Helsinki, Finland
| | - Per-Henrik Groop
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, FI-00290, Helsinki, Finland. .,Abdominal Center, Nephrology, University of Helsinki and Helsinki University Hospital, FI-00290, Helsinki, Finland. .,Research Programs Unit, Diabetes and Obesity, University of Helsinki, FI-00290, Helsinki, Finland. .,Department of Diabetes, Central Clinical School, Monash University, Melbourne, Victoria, Australia.
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8
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Coelho I, Pequito DC, Borghetti G, Aikawa J, Yamaguchi AA, de Brito GA, Yamazaki RK, Scorsato AP, Fernandes LC, Coimbra TM, Fernandez R. Chronic fish oil supplementation partially reverses renal alterations in mice fed with a high-fat diet. J Funct Foods 2016. [DOI: 10.1016/j.jff.2016.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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9
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Fish Oil Supplementation Reduces Cachexia and Tumor Growth While Improving Renal Function in Tumor-Bearing Rats. Lipids 2012; 47:1031-41. [DOI: 10.1007/s11745-012-3715-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 08/24/2012] [Indexed: 11/30/2022]
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10
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den Eynden JV, Ali SS, Horwood N, Carmans S, Brône B, Hellings N, Steels P, Harvey RJ, Rigo JM. Glycine and glycine receptor signalling in non-neuronal cells. Front Mol Neurosci 2009; 2:9. [PMID: 19738917 PMCID: PMC2737430 DOI: 10.3389/neuro.02.009.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Accepted: 07/23/2009] [Indexed: 11/13/2022] Open
Abstract
Glycine is an inhibitory neurotransmitter acting mainly in the caudal part of the central nervous system. Besides this neurotransmitter function, glycine has cytoprotective and modulatory effects in different non-neuronal cell types. Modulatory effects were mainly described in immune cells, endothelial cells and macroglial cells, where glycine modulates proliferation, differentiation, migration and cytokine production. Activation of glycine receptors (GlyRs) causes membrane potential changes that in turn modulate calcium flux and downstream effects in these cells. Cytoprotective effects were mainly described in renal cells, hepatocytes and endothelial cells, where glycine protects cells from ischemic cell death. In these cell types, glycine has been suggested to stabilize porous defects that develop in the plasma membranes of ischemic cells, leading to leakage of macromolecules and subsequent cell death. Although there is some evidence linking these effects to the activation of GlyRs, they seem to operate in an entirely different mode from classical neuronal subtypes.
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Affiliation(s)
- Jimmy Van den Eynden
- Institute of Biomedical Research, Hasselt University and transnationale Universiteit LimburgDiepenbeek, Belgium
| | - Sheen Saheb Ali
- Institute of Biomedical Research, Hasselt University and transnationale Universiteit LimburgDiepenbeek, Belgium
| | - Nikki Horwood
- Kennedy Institute of Rheumatology Division, Faculty of Medicine, Imperial College London, Charing Cross CampusLondon, UK
| | - Sofie Carmans
- Institute of Biomedical Research, Hasselt University and transnationale Universiteit LimburgDiepenbeek, Belgium
| | - Bert Brône
- Institute of Biomedical Research, Hasselt University and transnationale Universiteit LimburgDiepenbeek, Belgium
| | - Niels Hellings
- Institute of Biomedical Research, Hasselt University and transnationale Universiteit LimburgDiepenbeek, Belgium
| | - Paul Steels
- Institute of Biomedical Research, Hasselt University and transnationale Universiteit LimburgDiepenbeek, Belgium
| | - Robert J. Harvey
- Department of Pharmacology, School of Pharmacy, University of LondonLondon, UK
| | - Jean-Michel Rigo
- Institute of Biomedical Research, Hasselt University and transnationale Universiteit LimburgDiepenbeek, Belgium
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11
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Thomsen K, Shirley DG. Servo-control of water and sodium homeostasis during renal clearance measurements in conscious rats. Kidney Blood Press Res 2007; 30:323-31. [PMID: 17693706 DOI: 10.1159/000107074] [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: 03/06/2007] [Accepted: 06/11/2007] [Indexed: 11/19/2022] Open
Abstract
Servo-controlled fluid and sodium replacement during clearance studies is used in order to prevent loss of body fluid and sodium following diuretic/natriuretic procedures. However, even under control conditions, the use of this technique is sometimes associated with increases in proximal tubular fluid output (assessed by lithium clearance) and excretion rates. The present study examined the reason for these increases. The first series of experiments showed that one cause is volume overloading. This can occur if the servo system is activated from the start, i.e., during the establishment of a suitably high urine flow rate by constant infusion of hypotonic glucose solution. The second series of experiments showed that replacement of blood samples with donor blood can also lead to increases in fractional lithium excretion and accompanying increases in water and sodium excretion, a problem not seen when blood samples are replaced with the animal's own red blood cells resuspended in isotonic saline. When these pitfalls are avoided, servo-controlled sodium and fluid replacement is a reliable technique that makes it possible to study the effects of natriuretic and/or diuretic stimuli without interference from unwanted changes in extracellular volume.
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Affiliation(s)
- Klaus Thomsen
- Centre for Basic Psychiatric Research, Aarhus University Hospital, Risskov, Denmark.
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12
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Podoprigora GI, Nartsissov YR, Aleksandrov PN. Effect of glycine on microcirculation in pial vessels of rat brain. Bull Exp Biol Med 2006; 139:675-7. [PMID: 16224578 DOI: 10.1007/s10517-005-0375-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Single application of glycine in a final dose of 40 mg/kg to the surface of the parietal area of rat brain produced a potent vasodilatory effect. The diameter of arterioles increased to 250% from the baseline level 1-3 min after treatment. These changes persisted for 5-10 min. In the follow-up period the diameter of vessels progressively decreased to the baseline level. Repeated application of glycine in the same dose also induced dilation of arterioles. Application of physiological saline under similar conditions did not produce these changes.
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Affiliation(s)
- G I Podoprigora
- Institute of Cytochemistry and Molecular Pharmacology; Institute of General Pathology and Pathophysiology, Russian Academy of Medical Sciences, Moscow.
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13
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Guarnieri G, Biolo G, Zanetti M, Barazzoni R. Chronic systemic inflammation in uremia: Potential therapeutic approaches. Semin Nephrol 2004; 24:441-5. [PMID: 15490407 DOI: 10.1016/j.semnephrol.2004.06.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Systemic inflammation characterizes several chronic diseases including uremia. Inflammation may contribute to morbidity and mortality by enhancing protein-calorie malnutrition, infectious complications, and atherosclerosis and cardiovascular disease. Although inflammation in renal disease can be caused, at least in part, by reduced renal clearance of proinflammatory mediators (tumor necrosis factor [TNF]-alpha, interleukin [IL]-6), several pathogenetic mechanisms are likely to contribute to direct activation of the inflammatory process under these conditions. These mechanisms include accumulation of advance glycoxidation end products, production of reactive oxygen species and oxidative damage, and chronic infection. Support for direct activation of systemic inflammation provides a strong rationale for use of anti-inflammatory treatments in uremia. The current article describes the association between uremia and inflammation, provides evidence for activation of inflammatory process, and provides potential therapeutic approaches.
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Affiliation(s)
- Gianfranco Guarnieri
- Clinica Medica, Department of Clinical, Morphological and Technological Services, University of Trieste, Trieste, Italy.
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14
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Nielsen CB, Flyvbjerg A, Bruun JM, Forman A, Wogensen L, Thomsen K. Decreases in renal functional reserve and proximal tubular fluid output in conscious oophorectomized rats: normalization with sex hormone substitution. J Am Soc Nephrol 2004; 14:3102-10. [PMID: 14638909 DOI: 10.1097/01.asn.0000096262.18679.25] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Age-dependent glomerulosclerosis with reduced GFR develops earlier among men than among women. Therefore, whether female sex hormones could prevent the age-dependent decrease in GFR was investigated. The kidney function in oophorectomized rats treated with placebo (OOX group), estrogen (OOX+E(2) group), or estrogen plus progesterone (OOX+E(2)+P group) for 5 mo and in sham-operated rats (sham group) was examined. The rats were 13 mo of age at the time of the investigation. They were conscious and chronically instrumented. The results demonstrated that estrogen, alone or in combination with progesterone, was without effect on the baseline GFR and effective renal plasma flow but prevented severe decreases in the renal functional reserve and fractional proximal tubular fluid output (lithium clearance technique, fractional lithium excretion), which were observed in the OOX group. The renal functional reserve (estimated by stimulation with glycine) was -223 +/- 151, 483 +/- 129, 675 +/- 76, and 208 +/- 140 micro l/min in the OOX, OOX+E(2), OOX+E(2)+P, and sham groups, respectively. Fractional lithium excretion was 12.4 +/- 3.1, 26.8 +/- 2.0, 31.8 +/- 2.5, and 23.6 +/- 3.3% in the OOX, OOX+E(2), OOX+E(2)+P, and sham groups, respectively. In conclusion, oophorectomy at the age of 8 mo did not produce a decrease in baseline GFR in female rats within a period of 5 mo. However, oophorectomy led to severe decreases in the renal functional reserve and fractional proximal tubular fluid output. Both effects were prevented with administration of estrogen. Sham-operated rats demonstrated values for renal functional reserve and fractional lithium excretion that were between those observed for the OOX group and the groups treated with sex hormones.
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Affiliation(s)
- Camilla Birch Nielsen
- Department of Biological Psychiatry, Institute for Basic Psychiatric Research, Aarhus University Hospital, Aarhus, Denmark
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15
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Quan H, Athirakul K, Wetsel WC, Torres GE, Stevens R, Chen YT, Coffman TM, Caron MG. Hypertension and impaired glycine handling in mice lacking the orphan transporter XT2. Mol Cell Biol 2004; 24:4166-73. [PMID: 15121838 PMCID: PMC400459 DOI: 10.1128/mcb.24.10.4166-4173.2004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A family of orphan transporters has been discovered that are structurally related to the Na(+)-Cl(-)-dependent neurotransmitter transporters, including the dopamine transporter. One member of this family, the mouse XT2 gene, is predominantly expressed in the kidney and has 95% homology to rat ROSIT (renal osmotic stress-induced Na(+)-Cl(-) organic solute cotransporter). To study the physiological functions of this transporter, we generated XT2-knockout mice by gene targeting. XT2(-/-) mice develop and survive normally with no apparent abnormalities. To attempt to identify potential substrates for XT2, we screened urine from XT2-knockout mice by high-pressure liquid chromatography and mass spectrometry and found significantly elevated concentrations of glycine. To study glycine handling, XT2(+/+) and XT2(-/-) mice were injected with radiolabeled glycine, and urine samples were collected to monitor glycine excretion. After 2 h, XT2(-/-) mice were found to excrete almost twice as much glycine as the XT2(+/+) controls (P = 0.03). To determine whether the absence of the XT2 transporter affected sodium and fluid homeostasis, we measured systolic blood pressure by computerized tail-cuff manometry. Systolic blood pressure was significantly higher in XT2(-/-) mice (127 +/- 3 mmHg) than in wild-type controls (114 +/- 2 mmHg; P < 0.001). This difference in systolic blood pressure was maintained on high and low salt feeding. To examine whether the alteration in blood pressure and the defect in glycine handling were related, we measured systolic blood pressure in the XT2(-/-) mice during dietary glycine supplementation. Glycine loading caused systolic blood pressure to fall in the XT2(-/-) mice from 127 +/- 3 to 115 +/- 3 mmHg (P < 0.001), a level virtually identical to that of the wild-type controls. These data suggest that the XT2 orphan transporter is involved in glycine reabsorption and that the absence of this transporter is sufficient to cause hypertension.
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Affiliation(s)
- Hui Quan
- Department of Cell Biology, Howard Hughes Medical Institute Laboratories, Duke University Medical Center, Durham, North Carolina 27710, USA
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16
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Zhong Z, Wheeler MD, Li X, Froh M, Schemmer P, Yin M, Bunzendaul H, Bradford B, Lemasters JJ. L-Glycine: a novel antiinflammatory, immunomodulatory, and cytoprotective agent. Curr Opin Clin Nutr Metab Care 2003; 6:229-40. [PMID: 12589194 DOI: 10.1097/00075197-200303000-00013] [Citation(s) in RCA: 258] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW In recent years, evidence has mounted in favor of the antiinflammatory, immunomodulatory and cytoprotective effects of the simplest amino acid L-glycine. This article will focus on the recent findings about the responsible mechanisms of protection and review the beneficial effects of glycine in different disease states. RECENT FINDINGS Glycine protects against shock caused by hemorrhage, endotoxin and sepsis, prevents ischemia/reperfusion and cold storage/reperfusion injury to a variety of tissues and organs including liver, kidney, heart, intestine and skeletal muscle, and diminishes liver and renal injury caused by hepatic and renal toxicants and drugs. Glycine also protects against peptidoglycan polysaccharide-induced arthritis and inhibits gastric secretion and protects the gastric mucosa against chemically and stress-induced ulcers. Glycine appears to exert several protective effects, including antiinflammatory, immunomodulatory and direct cytoprotective actions. Glycine acts on inflammatory cells such as macrophages to suppress activation of transcription factors and the formation of free radicals and inflammatory cytokines. In the plasma membrane, glycine appears to activate a chloride channel that stabilizes or hyperpolarizes the plasma membrane potential. As a consequence, agonist-induced opening of L-type voltage-dependent calcium channels and the resulting increases in intracellular calcium ions are suppressed, which may account for the immunomodulatory and antiinflammatory effects of glycine. Lastly, glycine blocks the opening of relatively non-specific pores in the plasma membrane that occurs as the penultimate event leading to necrotic cell death. SUMMARY Multiple protective effects make glycine a promising treatment strategy for inflammatory diseases.
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Affiliation(s)
- Zhi Zhong
- Departments of Cell and Developmental Biology, Pharmacology, Surgery and Environmental Health, University of North Carolina at Chapel Hill, North Carolina 27599-7090, USA.
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