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Shimada S, Hoffmann BR, Yang C, Kurth T, Greene AS, Liang M, Dash RK, Cowley AW. Metabolic Responses of Normal Rat Kidneys to a High Salt Intake. FUNCTION 2023; 4:zqad031. [PMID: 37575482 PMCID: PMC10413938 DOI: 10.1093/function/zqad031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 06/06/2023] [Accepted: 06/12/2023] [Indexed: 08/15/2023] Open
Abstract
In this study, novel methods were developed, which allowed continuous (24/7) measurement of arterial blood pressure and renal blood flow in freely moving rats and the intermittent collection of arterial and renal venous blood to estimate kidney metabolic fluxes of O2 and metabolites. Specifically, the study determined the effects of a high salt (HS; 4.0% NaCl) diet upon whole kidney O2 consumption and arterial and renal venous plasma metabolomic profiles of normal Sprague-Dawley rats. A separate group of rats was studied to determine changes in the cortex and outer medulla tissue metabolomic and mRNAseq profiles before and following the switch from a 0.4% to 4.0% NaCl diet. In addition, targeted mRNA expression analysis of cortical segments was performed. Significant changes in the metabolomic and transcriptomic profiles occurred with feeding of the HS diet. A progressive increase of kidney O2 consumption was found despite a reduction in expression of most of the mRNA encoding enzymes of TCA cycle. A novel finding was the increased expression of glycolysis-related genes in Cx and isolated proximal tubular segments in response to an HS diet, consistent with increased release of pyruvate and lactate from the kidney to the renal venous blood. Data suggests that aerobic glycolysis (eg, Warburg effect) may contribute to energy production under these circumstances. The study provides evidence that kidney metabolism responds to an HS diet enabling enhanced energy production while protecting from oxidative stress and injury. Metabolomic and transcriptomic analysis of kidneys of Sprague-Dawley rats fed a high salt diet.
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Affiliation(s)
- Satoshi Shimada
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Brian R Hoffmann
- Mass Spectrometry and Protein Chemistry, Protein Sciences, The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Chun Yang
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Theresa Kurth
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Andrew S Greene
- Mass Spectrometry and Protein Chemistry, Protein Sciences, The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Mingyu Liang
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ranjan K Dash
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Biomedical Engineering, Medical College of Wisconsin and Marquette University, Milwaukee, WI 53226, USA
| | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Tahsin MR, Tithi TI, Mim SR, Haque E, Sultana A, Bahar NB, Ahmed R, Chowdhury JA, Chowdhury AA, Kabir S, Aktar F, Uddin MS, Amran MS. In Vivo and In Silico Assessment of Diabetes Ameliorating Potentiality and Safety Profile of Gynura procumbens Leaves. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2022; 2022:9095504. [PMID: 35096119 PMCID: PMC8791719 DOI: 10.1155/2022/9095504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 11/29/2021] [Accepted: 12/08/2021] [Indexed: 11/18/2022]
Abstract
BACKGROUND Diabetes mellitus is one of the most notable health dilemmas. Analyzing plants for new antidiabetic remedies has become an impressive territory for life science researchers. Gynura procumbens has long been used to treat diabetes. Thus, we strived to ascertain the hypoglycemic potentiality of extract of leaves of G. procumbens by in vivo and in silico approaches. METHODS Fresh leaves of G. procumbens were collected and shade-dried to prepare ethanolic extracts to evaluate pharmacological parameters. Diabetes was induced in rats via injecting alloxan through the intraperitoneal route at a dose of 150 mg/kg body weight. Humalyzer 3000 was used to perform a biochemical assay of collected samples from rats. Anti-hyperglycemic activity study along with overdose toxicity test was performed. The pharmacological activity of this plant was also evaluated through a molecular docking study. This in silico study investigated the binding affinity of natural ligands from G. procumbens against glycoside hydrolase enzymes. RESULTS We detected a peak plasma concentration of G. procumbens at 3 hours 45 minutes that is roughly similar to the peak plasma concentration of metformin. Again, in OGTT and anti-hyperglycemic tests, it has been ascertained that both plant extract and metformin can exert significant (P < 0.05) and highly significant (P < 0.01) hypoglycemic activity in a dose-dependent manner. Metformin exhibited better therapeutic efficacy than that of plant extract, but it possessed null statistical significance. Also, our safety profile expressed that, similar to metformin, the plant extract can restore the disturbed pathological state in a dose-oriented approach with a wide safety margin. In silico study also validated the potentialities of natural constituents of G. procumbens. Conclusion. This study suggested that G. procumbens can be considered as potential antidiabetic plant. Robust and meticulous investigation regarding plant chemistry and pharmacology in the future may bring about a new dimension that will aid in discovering antidiabetic drugs from this plant in the diabetes management system.
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Affiliation(s)
- Md. Rafat Tahsin
- Department of Pharmaceutical Sciences, North South University, Dhaka 1229, Bangladesh
| | - Tanzia Islam Tithi
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
| | - Sabiha Rahman Mim
- Department of Pharmaceutical Science, Uppsala University, Uppsala, Sweden
| | - Ehfazul Haque
- Molecular Pharmacology and Herbal Drug Research Laboratory, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
| | - Arifa Sultana
- Department of Pharmacy, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
| | - Nasiba Binte Bahar
- Department of Pharmacy, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
| | - Raju Ahmed
- Molecular Pharmacology and Herbal Drug Research Laboratory, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
| | - Jakir Ahmed Chowdhury
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
| | - Abu Asad Chowdhury
- Molecular Pharmacology and Herbal Drug Research Laboratory, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
| | - Shaila Kabir
- Molecular Pharmacology and Herbal Drug Research Laboratory, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
| | - Fahima Aktar
- Molecular Pharmacology and Herbal Drug Research Laboratory, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
| | - Md. Sahab Uddin
- Department of Pharmacy, Southeast University, Dhaka, Bangladesh
- Pharmakon Neuroscience Research Network, Dhaka, Bangladesh
| | - Md. Shah Amran
- Molecular Pharmacology and Herbal Drug Research Laboratory, Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka 1000, Bangladesh
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Sharma R, Tiwari S. Renal gluconeogenesis in insulin resistance: A culprit for hyperglycemia in diabetes. World J Diabetes 2021; 12:556-568. [PMID: 33995844 PMCID: PMC8107972 DOI: 10.4239/wjd.v12.i5.556] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/27/2021] [Accepted: 04/23/2021] [Indexed: 02/06/2023] Open
Abstract
Renal gluconeogenesis is one of the major pathways for endogenous glucose production. Impairment in this process may contribute to hyperglycemia in cases with insulin resistance and diabetes. We reviewed pertinent studies to elucidate the role of renal gluconeogenesis regulation in insulin resistance and diabetes. A consensus on the suppressive effect of insulin on kidney gluconeogenesis has started to build up. Insulin-resistant models exhibit reduced insulin receptor (IR) expression and/or post-receptor signaling in their kidney tissue. Reduced IR expression or post-receptor signaling can cause impairment in insulin’s action on kidneys, which may increase renal gluconeogenesis in the state of insulin resistance. It is now established that the kidney contributes up to 20% of all glucose production via gluconeogenesis in the post-absorptive phase. However, the rate of renal glucose release excessively increases in diabetes. The rise in renal glucose release in diabetes may contribute to fasting hyperglycemia and increased postprandial glucose levels. Enhanced glucose release by the kidneys and renal expression of the gluconeogenic-enzyme in diabetic rodents and humans further point towards the significance of renal gluconeogenesis. Overall, the available literature suggests that impairment in renal gluconeogenesis in an insulin-resistant state may contribute to hyperglycemia in type 2 diabetes.
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Affiliation(s)
- Rajni Sharma
- Department of Molecular Medicine and Biotechnology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India
| | - Swasti Tiwari
- Department of Molecular Medicine and Biotechnology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India
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Yamamoto S, Yamamoto M, Nakamura J, Mii A, Yamamoto S, Takahashi M, Kaneko K, Uchino E, Sato Y, Fukuma S, Imamura H, Matsuda M, Yanagita M. Spatiotemporal ATP Dynamics during AKI Predict Renal Prognosis. J Am Soc Nephrol 2020; 31:2855-2869. [PMID: 33046532 DOI: 10.1681/asn.2020050580] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/10/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Depletion of ATP in renal tubular cells plays the central role in the pathogenesis of kidney diseases. Nevertheless, inability to visualize spatiotemporal in vivo ATP distribution and dynamics has hindered further analysis. METHODS A novel mouse line systemically expressing an ATP biosensor (an ATP synthase subunit and two fluorophores) revealed spatiotemporal ATP dynamics at single-cell resolution during warm and cold ischemic reperfusion (IR) with two-photon microscopy. This experimental system enabled quantification of fibrosis 2 weeks after IR and assessment of the relationship between the ATP recovery in acute phase and fibrosis in chronic phase. RESULTS Upon ischemia induction, the ATP levels of proximal tubule (PT) cells decreased to the nadir within a few minutes, whereas those of distal tubule (DT) cells decreased gradually up to 1 hour. Upon reperfusion, the recovery rate of ATP in PTs was slower with longer ischemia. In stark contrast, ATP in DTs was quickly rebounded irrespective of ischemia duration. Morphologic changes of mitochondria in the acute phase support the observation of different ATP dynamics in the two segments. Furthermore, slow and incomplete ATP recovery of PTs in the acute phase inversely correlated with fibrosis in the chronic phase. Ischemia under conditions of hypothermia resulted in more rapid and complete ATP recovery with less fibrosis, providing a proof of concept for use of hypothermia to protect kidney tissues. CONCLUSIONS Visualizing spatiotemporal ATP dynamics during IR injury revealed higher sensitivity of PT cells to ischemia compared with DT cells in terms of energy metabolism. The ATP dynamics of PTs in AKI might provide prognostic information.
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Affiliation(s)
- Shinya Yamamoto
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masamichi Yamamoto
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Advanced Scientific Research Leaders Development Unit, Gunma University Graduate School of Medicine, Maebashi, Japan.,Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama, Japan
| | - Jin Nakamura
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Akiko Mii
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Shigenori Yamamoto
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masahiro Takahashi
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Keiichi Kaneko
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Eiichiro Uchino
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuki Sato
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Medical Innovation Center TMK Project, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Shingo Fukuma
- Department of Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiromi Imamura
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Michiyuki Matsuda
- Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Motoko Yanagita
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan .,Institute for the Advanced Study of Human Biology, Kyoto University, Kyoto, Japan
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Limbutara K, Chou CL, Knepper MA. Quantitative Proteomics of All 14 Renal Tubule Segments in Rat. J Am Soc Nephrol 2020; 31:1255-1266. [PMID: 32358040 DOI: 10.1681/asn.2020010071] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 03/09/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Previous research has used RNA sequencing in microdissected kidney tubules or single cells isolated from the kidney to profile gene expression in each type of kidney tubule epithelial cell. However, because proteins, not mRNA molecules, mediate most cellular functions, it is desirable to know the identity and amounts of each protein species to understand function. Recent improvements in the sensitivity of mass spectrometers offered us the ability to quantify the proteins expressed in each of 14 different renal tubule segments from rat. METHODS We manually dissected kidney tubules from rat kidneys and subjected samples to protein mass spectrometry. We used the "proteomic ruler" technique to estimate the number of molecules of each protein per cell. RESULTS Over the 44 samples analyzed, the average number of quantified proteins per segment was 4234, accounting for at least 99% of protein molecules in each cell. We have made the data publicly available online at the Kidney Tubule Expression Atlas website (https://esbl.nhlbi.nih.gov/KTEA/). Protein abundance along the renal tubule for many commonly studied water and solute transport proteins and metabolic enzymes matched expectations from prior localization studies, demonstrating the overall reliability of the data. The site features a "correlated protein" function, which we used to identify cell type-specific transcription factors expressed along the renal tubule. CONCLUSIONS We identified and quantified proteins expressed in each of the 14 segments of rat kidney tubules and used the proteomic data that we obtained to create an online information resource, the Kidney Tubule Expression Atlas. This resource will allow users throughout the world to browse segment-specific protein expression data and download them for their own research.
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Affiliation(s)
- Kavee Limbutara
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Chung-Lin Chou
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Mark A Knepper
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
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Edwards A, Palm F, Layton AT. A model of mitochondrial O 2 consumption and ATP generation in rat proximal tubule cells. Am J Physiol Renal Physiol 2020; 318:F248-F259. [PMID: 31790302 PMCID: PMC6985826 DOI: 10.1152/ajprenal.00330.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/18/2019] [Accepted: 11/25/2019] [Indexed: 11/22/2022] Open
Abstract
Oxygen tension in the kidney is mostly determined by O2 consumption (Qo2), which is, in turn, closely linked to tubular Na+ reabsorption. The objective of the present study was to develop a model of mitochondrial function in the proximal tubule (PT) cells of the rat renal cortex to gain more insight into the coupling between Qo2, ATP formation (GATP), ATP hydrolysis (QATP), and Na+ transport in the PT. The present model correctly predicts in vitro and in vivo measurements of Qo2, GATP, and ATP and Pi concentrations in PT cells. Our simulations suggest that O2 levels are not rate limiting in the proximal convoluted tubule, absent large metabolic perturbations. The model predicts that the rate of ATP hydrolysis and cytoplasmic pH each substantially regulate the GATP-to-Qo2 ratio, a key determinant of the number of Na+ moles actively reabsorbed per mole of O2 consumed. An isolated increase in QATP or in cytoplasmic pH raises the GATP-to-Qo2 ratio. Thus, variations in Na+ reabsorption and pH along the PT may, per se, generate axial heterogeneities in the efficiency of mitochondrial metabolism and Na+ transport. Our results also indicate that the GATP-to-Qo2 ratio is strongly impacted not only by H+ leak permeability, which reflects mitochondrial uncoupling, but also by K+ leak pathways. Simulations suggest that the negative impact of increased uncoupling in the diabetic kidney on mitochondrial metabolic efficiency is partly counterbalanced by increased rates of Na+ transport and ATP consumption. This model provides a framework to investigate the role of mitochondrial dysfunction in acute and chronic renal diseases.
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Affiliation(s)
- Aurélie Edwards
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | - Fredrik Palm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Anita T Layton
- Departments of Mathematics, Biomedical Engineering, and Medicine, Duke University, Durham, North Carolina
- Departments of Applied Mathematics and Biology, School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
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Clark JZ, Chen L, Chou CL, Jung HJ, Lee JW, Knepper MA. Representation and relative abundance of cell-type selective markers in whole-kidney RNA-Seq data. Kidney Int 2019; 95:787-796. [PMID: 30826016 DOI: 10.1016/j.kint.2018.11.028] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 10/22/2018] [Accepted: 11/08/2018] [Indexed: 01/08/2023]
Abstract
Bulk-tissue RNA-Seq is increasingly being used in the study of physiological and pathophysiological processes in the kidney; however, the presence of multiple cell types in kidney tissue complicates data interpretation. We addressed the question of which cell types are represented in whole-kidney RNA-Seq data in order to identify circumstances in which bulk-kidney RNA-Seq can be successfully interpreted. We carried out RNA-Seq in mouse whole kidneys and in microdissected renal tubule segments. To aid in the interpretation of the data, we compiled a database of cell-type selective protein markers for 43 cell types believed to be present in kidney tissue. The whole-kidney RNA-Seq analysis identified transcripts corresponding to 17,742 genes, distributed over 5 orders of magnitude of expression level. Markers for all 43 curated cell types were detectable. Analysis of the cellular makeup of mouse and rat kidney, calculated from published literature, suggests that proximal tubule cells account for more than half of the mRNA in a kidney. Comparison of RNA-Seq data from microdissected proximal tubules with data from whole kidney supports this view. RNA-Seq data for cell-type selective markers in bulk-kidney samples provide a valid means to identify changes in minority-cell abundances in kidney tissue. Because proximal tubules make up a substantial fraction of whole-kidney samples, changes in proximal tubule gene expression can be assessed presumptively by bulk-kidney RNA-Seq, although results could potentially be complicated by the presence of mRNA from other cell types.
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Affiliation(s)
- Jevin Z Clark
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Lihe Chen
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Chung-Lin Chou
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Hyun Jun Jung
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jae Wook Lee
- Nephrology Clinic, National Cancer Center, Goyang, South Korea
| | - Mark A Knepper
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
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Song H, Yoon SP, Kim J. Poly(ADP-ribose) polymerase regulates glycolytic activity in kidney proximal tubule epithelial cells. Anat Cell Biol 2016; 49:79-87. [PMID: 27382509 PMCID: PMC4927434 DOI: 10.5115/acb.2016.49.2.79] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 04/02/2016] [Accepted: 04/25/2016] [Indexed: 12/28/2022] Open
Abstract
After renal injury, selective damage occurs in the proximal tubules as a result of inhibition of glycolysis. The molecular mechanism of damage is not known. Poly(ADP-ribose) polymerase (PARP) activation plays a critical role of proximal tubular cell death in several renal disorders. Here, we studied the role of PARP on glycolytic flux in pig kidney proximal tubule epithelial LLC-PK1 cells using XFp extracellular flux analysis. Poly(ADP-ribosyl)ation by PARP activation was increased approximately 2-fold by incubation of the cells in 10 mM glucose for 30 minutes, but treatment with the PARP inhibitor 3-aminobenzamide (3-AB) does-dependently prevented the glucose-induced PARP activation (approximately 14.4% decrease in 0.1 mM 3-AB–treated group and 36.7% decrease in 1 mM 3-AB–treated group). Treatment with 1 mM 3-AB significantly enhanced the glucose-mediated increase in the extracellular acidification rate (61.1±4.3 mpH/min vs. 126.8±6.2 mpH/min or approximately 2-fold) compared with treatment with vehicle, indicating that PARP inhibition increases only glycolytic activity during glycolytic flux including basal glycolysis, glycolytic activity, and glycolytic capacity in kidney proximal tubule epithelial cells. Glucose increased the activities of glycolytic enzymes including hexokinase, phosphoglucose isomerase, phosphofructokinase-1, glyceraldehyde-3-phosphate dehydrogenase, enolase, and pyruvate kinase in LLC-PK1 cells. Furthermore, PARP inhibition selectively augmented the activities of hexokinase (approximately 1.4-fold over vehicle group), phosphofructokinase-1 (approximately 1.6-fold over vehicle group), and glyceraldehyde-3-phosphate dehydrogenase (approximately 2.2-fold over vehicle group). In conclusion, these data suggest that PARP activation may regulate glycolytic activity via poly(ADP-ribosyl)ation of hexokinase, phosphofructokinase-1, and glyceraldehyde-3-phosphate dehydrogenase in kidney proximal tubule epithelial cells.
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Affiliation(s)
- Hana Song
- Department of Biomedicine and Drug Development, Jeju National University, Jeju, Korea
| | - Sang Pil Yoon
- Department of Anatomy, Jeju National University School of Medicine, Jeju, Korea
| | - Jinu Kim
- Department of Biomedicine and Drug Development, Jeju National University, Jeju, Korea.; Department of Anatomy, Jeju National University School of Medicine, Jeju, Korea
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Abstract
Per milligram of tissue, only the heart exceeds the kidney's abundance of mitochondria. Not surprisingly, renal mitochondria are most densely concentrated in the epithelium of the nephron, at sites where the chemical work of moving solutes against electrochemical gradients places large and constant demands for adenosine triphosphate. Derangements of renal epithelial mitochondria appear to be a hallmark for diverse forms of acute kidney injury (AKI). The pathogenesis of multiple-organ dysfunction syndrome in sepsis is complex, but a substantial body of experimental and observational human data supports the twin concepts that mitochondrial dysfunction contributes to impaired filtration and that recovery of mitochondrial structure and function is essential for recovery from sepsis-associated AKI. These insights have suggested novel methods to diagnose, stratify, prevent, or even treat this common and deadly complication of critical illness. This review will do the following: (1) describe the structure and functions of healthy mitochondria and how renal energy metabolism relates to solute transport; (2) provide an overview of the evidence linking mitochondrial pathology to renal disease; (3) summarize the mitochondrial lesions observed in septic AKI; (4) analyze the role of mitochondrial processes including fission/fusion, mitophagy, and biogenesis in the development of septic AKI and recovery from this disease; and (5) explore the potential for therapeutically targeting mitochondria to prevent or treat septic AKI.
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10
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Layton AT, Vallon V, Edwards A. Modeling oxygen consumption in the proximal tubule: effects of NHE and SGLT2 inhibition. Am J Physiol Renal Physiol 2015; 308:F1343-57. [PMID: 25855513 DOI: 10.1152/ajprenal.00007.2015] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 04/03/2015] [Indexed: 01/03/2023] Open
Abstract
The objective of this study was to investigate how physiological, pharmacological, and pathological conditions that alter sodium reabsorption (TNa) in the proximal tubule affect oxygen consumption (QO2 ) and Na(+) transport efficiency (TNa/QO2 ). To do so, we expanded a mathematical model of solute transport in the proximal tubule of the rat kidney. The model represents compliant S1, S2, and S3 segments and accounts for their specific apical and basolateral transporters. Sodium is reabsorbed transcellularly, via apical Na(+)/H(+) exchangers (NHE) and Na(+)-glucose (SGLT) cotransporters, and paracellularly. Our results suggest that TNa/QO2 is 80% higher in S3 than in S1-S2 segments, due to the greater contribution of the passive paracellular pathway to TNa in the former segment. Inhibition of NHE or Na-K-ATPase reduced TNa and QO2 , as well as Na(+) transport efficiency. SGLT2 inhibition also reduced proximal tubular TNa but increased QO2 ; these effects were relatively more pronounced in the S3 vs. the S1-S2 segments. Diabetes increased TNa and QO2 and reduced TNa/QO2 , owing mostly to hyperfiltration. Since SGLT2 inhibition lowers diabetic hyperfiltration, the net effect on TNa, QO2 , and Na(+) transport efficiency in the proximal tubule will largely depend on the individual extent to which glomerular filtration rate is lowered.
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Affiliation(s)
- Anita T Layton
- Department of Mathematics, Duke University, Durham, North Carolina;
| | - Volker Vallon
- Departments of Medicine and Pharmacology, University of California San Diego, La Jolla, California, and San Diego Veterans Affairs Healthcare System, San Diego, California; and
| | - Aurélie Edwards
- Sorbonne Universités, Université Pierre et Marie Curie (UMPC) 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France
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11
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Abstract
The human kidneys produce approximately 160-170 L of ultrafiltrate per day. The proximal tubule contributes to fluid, electrolyte, and nutrient homeostasis by reabsorbing approximately 60%-70% of the water and NaCl, a greater proportion of the NaHCO3, and nearly all of the nutrients in the ultrafiltrate. The proximal tubule is also the site of active solute secretion, hormone production, and many of the metabolic functions of the kidney. This review discusses the transport of NaCl, NaHCO3, glucose, amino acids, and two clinically important anions, citrate and phosphate. NaCl and the accompanying water are reabsorbed in an isotonic fashion. The energy that drives this process is generated largely by the basolateral Na(+)/K(+)-ATPase, which creates an inward negative membrane potential and Na(+)-gradient. Various Na(+)-dependent countertransporters and cotransporters use the energy of this gradient to promote the uptake of HCO3 (-) and various solutes, respectively. A Na(+)-dependent cotransporter mediates the movement of HCO3 (-) across the basolateral membrane, whereas various Na(+)-independent passive transporters accomplish the export of various other solutes. To illustrate its homeostatic feat, the proximal tubule alters its metabolism and transport properties in response to metabolic acidosis. The uptake and catabolism of glutamine and citrate are increased during acidosis, whereas the recovery of phosphate from the ultrafiltrate is decreased. The increased catabolism of glutamine results in increased ammoniagenesis and gluconeogenesis. Excretion of the resulting ammonium ions facilitates the excretion of acid, whereas the combined pathways accomplish the net production of HCO3 (-) ions that are added to the plasma to partially restore acid-base balance.
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Affiliation(s)
- Norman P Curthoys
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado; and
| | - Orson W Moe
- Departments of Internal Medicine and Physiology, University of Texas Southwestern Medical Center, Dallas, Texas
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Gall JM, Wong V, Pimental DR, Havasi A, Wang Z, Pastorino JG, Bonegio RGB, Schwartz JH, Borkan SC. Hexokinase regulates Bax-mediated mitochondrial membrane injury following ischemic stress. Kidney Int 2011; 79:1207-16. [PMID: 21430642 DOI: 10.1038/ki.2010.532] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hexokinase (HK), the rate-limiting enzyme in glycolysis, controls cell survival by promoting metabolism and/or inhibiting apoptosis. Since HK isoforms I and II have mitochondrial targeting sequences, we attempted to separate the protective effects of HK on cell metabolism from those on apoptosis. We exposed renal epithelial cells to metabolic stress causing ATP depletion in the absence of glucose and found that this activated glycogen synthase kinase 3β (GSK3β) and Bax caused mitochondrial membrane injury and apoptosis. ATP depletion led to a progressive HK II dissociation from mitochondria, released mitochondrial apoptosis inducing factor and cytochrome c into the cytosol, activated caspase-3, and reduced cell survival. Compared with control, adenoviral-mediated HK I or II overexpression improved cell survival following stress, but did not prevent GSK3β or Bax activation, improve ATP content, or reduce mitochondrial fragmentation. HK I or HK II overexpression increased mitochondria-associated isoform-specific HK content, and decreased mitochondrial membrane injury and apoptosis after stress. In vivo, HK II localized exclusively to the proximal tubule. Ischemia reduced total renal HK II content and dissociated HK II from proximal tubule mitochondria. In cells overexpressing HK II, Bax and HK II did not interact before or after stress. While the mechanism by which HK antagonizes Bax-mediated apoptosis is unresolved by these studies, one possible scenario is that the two proteins compete for a common binding site on the outer mitochondrial membrane.
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Affiliation(s)
- Jonathan M Gall
- Renal Section, Department of Medicine, Boston Medical Center, Boston University School of Medicine, Massachusetts, USA
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13
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Wilson-O'Brien AL, Patron N, Rogers S. Evolutionary ancestry and novel functions of the mammalian glucose transporter (GLUT) family. BMC Evol Biol 2010; 10:152. [PMID: 20487568 PMCID: PMC2890515 DOI: 10.1186/1471-2148-10-152] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 05/21/2010] [Indexed: 01/25/2023] Open
Abstract
Background In general, sugar porters function by proton-coupled symport or facilitative transport modes. Symporters, coupled to electrochemical energy, transport nutrients against a substrate gradient. Facilitative carriers transport sugars along a concentration gradient, thus transport is dependent upon extracellular nutrient levels. Across bacteria, fungi, unicellular non-vertebrates and plants, proton-coupled hexose symport is a crucial process supplying energy under conditions of nutrient flux. In mammals it has been assumed that evolution of whole body regulatory mechanisms would eliminate this need. To determine whether any isoforms bearing this function might be conserved in mammals, we investigated the relationship between the transporters of animals and the proton-coupled hexose symporters found in other species. Results We took a comparative genomic approach and have performed the first comprehensive and statistically supported phylogenetic analysis of all mammalian glucose transporter (GLUT) isoforms. Our data reveals the mammalian GLUT proteins segregate into five distinct classes. This evolutionary ancestry gives insight to structure, function and transport mechanisms within the groups. Combined with biological assays, we present novel evidence that, in response to changing nutrient availability and environmental pH, proton-coupled, active glucose symport function is maintained in mammalian cells. Conclusions The analyses show the ancestry, evolutionary conservation and biological importance of the GLUT classes. These findings significantly extend our understanding of the evolution of mammalian glucose transport systems. They also reveal that mammals may have conserved an adaptive response to nutrient demand that would have important physiological implications to cell survival and growth.
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Affiliation(s)
- Amy L Wilson-O'Brien
- Department of Medicine, St, Vincent's, The University of Melbourne, Fitzroy, Victoria 3065, Australia
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Chen J, Layton AT, Edwards A. A mathematical model of O2 transport in the rat outer medulla. I. Model formulation and baseline results. Am J Physiol Renal Physiol 2009; 297:F517-36. [PMID: 19403646 DOI: 10.1152/ajprenal.90496.2008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mammalian kidney is particularly vulnerable to hypoperfusion, because the O(2) supply to the renal medulla barely exceeds its O(2) requirements. In this study, we examined the impact of the complex structural organization of the rat outer medulla (OM) on O(2) distribution. We extended the region-based mathematical model of the rat OM developed by Layton and Layton (Am J Physiol Renal Physiol 289: F1346-F1366, 2005) to incorporate the transport of RBCs, Hb, and O(2). We considered basal cellular O(2) consumption and O(2) consumption for active transport of NaCl across medullary thick ascending limb epithelia. Our model predicts that the structural organization of the OM results in significant Po(2) gradients in the axial and radial directions. The segregation of descending vasa recta, the main supply of O(2), at the center and immediate periphery of the vascular bundles gives rise to large radial differences in Po(2) between regions, limits O(2) reabsorption from long descending vasa recta, and helps preserve O(2) delivery to the inner medulla. Under baseline conditions, significantly more O(2) is transferred radially between regions by capillary flow, i.e., advection, than by diffusion. In agreement with experimental observations, our results suggest that 79% of the O(2) supplied to the medulla is consumed in the OM and that medullary thick ascending limbs operate on the brink of hypoxia.
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Affiliation(s)
- Jing Chen
- Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts 02155, UAS
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15
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Devalaraja-Narashimha K, Padanilam BJ. PARP-1 inhibits glycolysis in ischemic kidneys. J Am Soc Nephrol 2008; 20:95-103. [PMID: 19056868 DOI: 10.1681/asn.2008030325] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
After ischemic renal injury (IRI), selective damage occurs in the S(3) segments of the proximal tubules as a result of inhibition of glycolysis, but the mechanism of this inhibition is unknown. We previously reported that inhibition of poly(ADP-ribose) polymerase-1 (PARP-1) activity protects against ischemia-induced necrosis in proximal tubules by preserving ATP levels. Here, we tested whether PARP-1 activation in proximal tubules after IRI leads to poly(ADP-ribosyl)ation of the key glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a modification that inhibits its activity. Using in vitro and in vivo models, under hypoxic conditions, we detected poly(ADP-ribosyl)ation and reduced activity of GAPDH; inhibition of PARP-1 activity restored GAPDH activity and ATP levels. Inhibition of GAPDH with iodoacetate exacerbated ATP depletion, cytotoxicity, and necrotic cell death of LLCPK(1) cells subjected to hypoxic conditions, whereas inhibition of PARP-1 activity was cytoprotective. In conclusion, these data indicate that poly(ADP-ribosyl)ation of GAPDH and the subsequent inhibition of anaerobic respiration exacerbate ATP depletion selectively in the proximal tubule after IRI.
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Affiliation(s)
- Kishor Devalaraja-Narashimha
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA
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16
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Biju MP, Akai Y, Shrimanker N, Haase VH. Protection of HIF-1-deficient primary renal tubular epithelial cells from hypoxia-induced cell death is glucose dependent. Am J Physiol Renal Physiol 2005; 289:F1217-26. [PMID: 16048903 DOI: 10.1152/ajprenal.00233.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ischemic acute renal failure is a frequent clinical problem in hospitalized patients and is associated with significant mortality. Hypoxia-inducible factor 1 (HIF-1) mediates cellular adaptation to hypoxia by regulating biological processes important for cell survival, which include glycolysis, angiogenesis, erythropoiesis, apoptosis, and proliferation. To investigate the role of HIF-1 in hypoxia-induced renal epithelial cell death, we generated mice that allow inactivation of HIF-1α by tetracycline-inducible Cre-loxP-mediated recombination in primary renal proximal tubule cells (PRPTC), resulting in a suppression of HIF-1-mediated gene transcription during oxygen deprivation. In the absence of glucose, the onset and the degree of hypoxia-induced cell death in HIF-1-deficient PRPTC were comparable to wild-type cells. However, when glucose availability was limited, the onset of cell death was delayed in either PRPTC that were HIF-1 deficient or in wild-type PRPTC when glycolysis or glucose uptake was partially inhibited. Our findings suggest in an in vitro genetic model that 1) the generation of adequate energy levels for the maintenance of PRPTC viability under hypoxia does not require HIF-1 and 2) that HIF-1 regulates the timing of hypoxia-induced cell death and apoptosis onset through its effects on glucose consumption.
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Affiliation(s)
- Mangatt P Biju
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, 19104-6144, USA
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17
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Han HJ, Sigurdson WJ, Nickerson PA, Taub M. Both mitogen activated protein kinase and the mammalian target of rapamycin modulate the development of functional renal proximal tubules in matrigel. J Cell Sci 2004; 117:1821-33. [PMID: 15075242 DOI: 10.1242/jcs.01020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Tubules may arise during branching morphogenesis through several mechanisms including wrapping, budding, cavitation and cord hollowing. In this report we present evidence that is consistent with renal proximal tubule formation through a process of cord hollowing (a process that requires the concomitant establishment of apicobasal polarity and lumen formation). Pockets of lumen filled with Lucifer Yellow were observed within developing cords of rabbit renal proximal tubule cells in matrigel. The observation of Lucifer Yellow accumulation suggests functional polarization. In the renal proximal tubule Lucifer Yellow is initially transported intracellularly by means of a basolaterally oriented p-aminohippurate transport system, followed by apical secretion into the lumen of the nephron. Consistent with such polarization in developing tubules, Triticum vulgare was observed to bind to the lumenal membranes within pockets of Lucifer Yellow-filled lumens. As this lectin binds apically in the rabbit renal proximal tubule, T. vulgare binding is indicative of the emergence of an apical domain before the formation of a contiguous lumen. Both epidermal growth factor and hepatocyte growth factor stimulated the formation of transporting tubules. The stimulatory effect of both epidermal growth factor and hepatocyte growth factor on tubulogenesis was inhibited by PD98059, a mitogen activated protein kinase kinase inhibitor, rather than by wortmannin, an inhibitor of phosphoinositide 3-kinase. Nevertheless, Lucifer Yellow-filled lumens were observed in tubules that formed in the presence of PD98059 as well as with wortmannin, indicating that these drugs did not prevent the process of cavitation. By contrast, rapamycin, an inhibitor of the mammalian target of rapamycin, prevented the process of cavitation without affecting the frequency of formation of developing cords. Multicellular cysts were observed to form in 8-bromocyclic AMP-treated cultures. As these cysts did not similarly accumulate Lucifer Yellow lumenally, it is very likely that processes other than organic anion accumulation are involved in the process of cystogenesis, including the Na,K-ATPase.
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Affiliation(s)
- Ho Jae Han
- Department of Veterinary Physiology, College of Veterinary Medicine, Hormone Research Center, Chonnam National University, Gwangju 500-757, Korea
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18
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Kieferle S, Fong P, Bens M, Vandewalle A, Jentsch TJ. Two highly homologous members of the ClC chloride channel family in both rat and human kidney. Proc Natl Acad Sci U S A 1994; 91:6943-7. [PMID: 8041726 PMCID: PMC44314 DOI: 10.1073/pnas.91.15.6943] [Citation(s) in RCA: 207] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
We have cloned two closely related putative Cl- channels from both rat kidney (designated rClC-K1 and rClC-K2) and human kidney (hClC-Ka and hClC-Kb) by sequence homology to the ClC family of voltage-gated Cl- channels. While rClC-K1 is nearly identical to ClC-K1, a channel recently isolated by a similar strategy, rClC-K2 is 80% identical to rClC-K1 and is encoded by a different gene. hClC-Ka and hClC-Kb show approximately 90% identity, while being approximately 80% identical to the rat proteins. All ClC-K gene products are expressed predominantly in the kidney. While rClC-K1 is expressed strongly in the cortical thick ascending limb and the distal convoluted tubule, with minor expression in the S3 segment of the proximal tubule and the cortical collecting tubule, rClC-K2 is expressed in all segments of the nephron examined, including the glomerulus. Since they are related more closely to each other than to the rat proteins, hClC-Ka and hClC-Kb cannot be regarded as strict homologs of rClC-K1 or rClC-K2. After injection of ClC-K cRNAs into oocytes, corresponding proteins were made and glycosylated, though no additional Cl- currents were detectable. Glycosylation occurs between domains D8 and D9, leading to a revision of the transmembrane topology model for ClC channels.
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Affiliation(s)
- S Kieferle
- Centre for Molecular Neurobiology (ZMNH), Hamburg University, Germany
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19
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Lacave R, Bens M, Cartier N, Vallet V, Robine S, Pringault E, Kahn A, Vandewalle A. Functional properties of proximal tubule cell lines derived from transgenic mice harboring L-pyruvate kinase-SV40 (T) antigen hybrid gene. J Cell Sci 1993; 104 ( Pt 3):705-12. [PMID: 8391010 DOI: 10.1242/jcs.104.3.705] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study describes the functional characterization of two cell lines derived from the proximal convoluted (PKSV-PCT cells) and proximal straight (PKSV-PR) tubules microdissected out from kidneys of transgenic mice harboring the simian virus 40 (SV40) large T and small t antigens placed under the control of the rat L-type pyruvate kinase (L-PK) 5′ regulatory sequence. Both cell lines exhibited cellular cyclic AMP stimulated by parathormone (PTH) and calcitonin (CT) and a sodium-dependent glucose transporter. Uptake of the fluid-phase marker [3H]inulin showed that both cell lines grown on filters exhibited biphasic apical and basolateral endocytic rates. Results from Northern blot analysis indicate that the expression of the T antigen gene (Tag) is dependent on the concentration of D-glucose in the medium and show that the L-PK construct has maintained its capacity for up- or down-regulation by carbohydrates. Replacement of D-glucose by neoglucogenic substrates (lactate, oxaloacetate) blunted the expression of Tag transcripts and induced arrest of cell growth. Compared to cell grown in D-glucose-enriched medium, the hormonal sensitivities to PTH and CT and the sodium-dependent glucose uptake were unchanged whereas quiescent cells exhibited increased hydrolase content. Thus the proximal function has been preserved in these cultured cells derived from tissue-specific targeted oncogenesis in transgenic mice. As the expression of Tag transcripts is controlled by D-glucose, the structural and physiological characteristics of these cell lines can be studied in either quiescent or active growth conditions.
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Affiliation(s)
- R Lacave
- Laboratoire Hospitalo-Universitaire d'Histologie et de Biologie Tumorale, Hôpital Tenon, Paris, France
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20
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Tsuchiya K, Wang W, Giebisch G, Welling PA. ATP is a coupling modulator of parallel Na,K-ATPase-K-channel activity in the renal proximal tubule. Proc Natl Acad Sci U S A 1992; 89:6418-22. [PMID: 1321439 PMCID: PMC49512 DOI: 10.1073/pnas.89.14.6418] [Citation(s) in RCA: 121] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A fundamental and essential property of nearly all salt-transporting epithelia is the tight parallel coupling between the magnitude of the K-conductive pathway at the basolateral membrane and the activity of the Na,K-dependent ATPase (Na,K-ATPase). In the present study, we demonstrate that the coupling response in the renal proximal tubule is governed, at least in part, through the interaction between ATP-sensitive K channels and Na,K-ATPase-mediated changes in intracellular ATP levels. First, we identified a K-selective channel at the basolateral membrane, which is inhibited by the cytosolic addition of ATP. Second, conventional microelectrode analysis in the isolated perfused proximal straight tubule revealed that these channels are the major determinant of the macroscopic K conductance so that ATP-mediated changes in the open probability of the K channel could alter the extent of K recycling. Indeed, the increase in the macroscopic K conductance upon stimulation of transcellular Na transport and pump activity was found to be paralleled by a decrease in intracellular ATP. Finally, a causal link between parallel Na,K-ATPase-K-channel activity and ATP was established by the finding that intracellular ATP loading uncoupled the response. With our recent observations that similar ATP-sensitive K channels are expressed abundantly in other epithelia, we postulate that ATP may act as a universal coupling modulator of parallel Na,K-ATPase-K-channel activity.
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Affiliation(s)
- K Tsuchiya
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510
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21
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Vandewalle A, Lelongt B, Geniteau-Legendre M, Baudouin B, Antoine M, Estrade S, Chatelet F, Verroust P, Cassingena R, Ronco P. Maintenance of proximal and distal cell functions in SV40-transformed tubular cell lines derived from rabbit kidney cortex. J Cell Physiol 1989; 141:203-21. [PMID: 2550481 DOI: 10.1002/jcp.1041410128] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This paper reports the preparation and describes the properties of three renal tubular cell lines derived using SV40 infection of primary cultures of rabbit kidney cortical cells, enriched in proximal cells. RC.SV1 was initially derived from cultures grown in the presence of fetal calf serum exhibiting a low degree of proximal differentiation. The cells were subsequently adapted to grow in serum-free hormonally defined medium and display basic properties of proximal tubule cells including well-developed apical microvilli, strong expression of brush-border hydrolases, Na+-coupled glucose uptake, and increased cyclic AMP production when exposed to PTH. The other two cell lines were derived from cultures in serum-free hormonally defined medium and propagated in the same medium. They are characterized by some common properties including rare and short microvilli, low expression of apical hydrolases, and low or undetectable Na+-dependent glucose uptake, but differ by their abilities to respond by an increase in cAMP to various hormonal stimuli. RC.SV2 cells are sensitive to calcitonin and to a lesser extent to isoproterenol and PTH, suggesting that they may originate from the thick ascending limb of Henle's loop and the bright portion of the distal tubule. RC.SV3 responds essentially to isoproterenol and arginine vasopressin, suggesting a more distal origin (late distal and initial collecting tubule). Emergence of distal cell lines from cultures exhibiting proximal characteristics may be related to distal cell overgrowth as suggested by analysis of growth kinetics and increased Na+/H+ exchanger activity in RC.SV2 compared with RC.SV1.
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22
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Trinh-Trang-Tan MM, Bouby N, Coutaud C, Bankir L. Quick isolation of rat medullary thick ascending limbs. Enzymatic and metabolic characterization. Pflugers Arch 1986; 407:228-34. [PMID: 3018664 DOI: 10.1007/bf00580681] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
This paper describes a rapid and simple method for isolation of medullary thick ascending limbs (MTAL) from rat kidney. The technique takes advantage of the fact that MTAL represents a high fraction of the inner stripe (IS) tissue in the outer medulla, and that this nephron segment is more resistant than others to mechanical and enzymatic disruption. Special attention was given in the design of each step of the isolation procedure in order to improve purity and yield of the preparation. Major steps are the following: careful dissection of the IS; cutting IS tissue into small pieces of regular size (approximately equal to 1 mm3); mild and brief enzymatic hydrolysis in a 65 U/ml collagenase solution; separation of long MTAL segments from other tubule fragments and cells, and washing of the collagenase solution, on a nylon sieve (100 microns opening). This technique does not require lengthy centrifugations and provides about 6 mg fresh tissue (= 1 mg protein) from two rat kidneys in 2 h. Light microscopy and transmission electron microscopy show a good purity (at least 95%) and good preservation of TAL ultrastructural morphology. Adenylate cyclase responsiveness to arginine-vasopressin (AVP), glucagon (GLU) and salmon calcitonin (SCT) of the MTAL suspension is similar to that reported for single microdissected rat MTAL. Viability of the MTALs was demonstrated by the ability to accumulate cyclic AMP in presence of AVP, GLU, SCT and forskolin. Normal oxygen consumption was 45.1 +/- 2.4 (SEM) microliter . mg protein-1 . h-1 (n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)
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Wirthensohn G, Guder WG. Stimulation of phospholipid turnover by angiotensin II and phenylephrine in proximal convoluted tubules microdissected from mouse nephron. Pflugers Arch 1985; 404:94-6. [PMID: 4011403 DOI: 10.1007/bf00581500] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Angiotensin II and phenylephrine significantly increased phospholipid turnover in cortical tubule suspensions. To further localize this effect we studied the 32P incorporation into phosphatidylcholine (PC) and phosphatidylinositol (PI) in single dissected proximal convoluted tubules of mouse nephron. Both hormones significantly stimulated 32P labeling of PC and PI indicating that the proximal tubule is a target site of angiotensin II and phenylephrine action.
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24
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Lawrence GM, Trayer IP, Walker DG. Histochemical and immunohistochemical localization of hexokinase isoenzymes in normal rat liver. THE HISTOCHEMICAL JOURNAL 1984; 16:1099-111. [PMID: 6094398 DOI: 10.1007/bf01002897] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Histochemical and immunohistochemical procedures have been used to examine the localization of three of the four hexokinase isoenzymes present in the liver of fed female Wistar rats. Distinctive distribution patterns were found for hexokinase type I and glucokinase but hexokinase type II was not detectable. Hexokinase type I was identified in sinusoidal cells and in bile duct epithelia, nerves and arteries in the portal triad. Glucokinase, the major isoenzyme, was confined to parenchymal cells where it was present in much higher amounts in perivenous compared with periportal hepatocytes. Staining within these two zones was not homogeneous and each had a mosaic appearance caused by the presence of a few hepatocytes containing little or no glucokinase amongst the majority of darkly stained cells in perivenous areas and a few darkly stained cells amongst the majority of unstained cells in periportal areas. Hence, hepatocytes in situ are a strikingly heterogeneous population of cells. Their metabolic status cannot be controlled simply by the differential supply of oxygen, substrates and hormones to different regions of the liver acini as proposed in the metabolic zonation model. Phenotypic differences may exist between cells within a given metabolic zone which influence their ability to respond to different environmental conditions.
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Nakamura R, Emmanouel DS, Katz AI. Insulin binding sites in various segments of the rabbit nephron. J Clin Invest 1983; 72:388-92. [PMID: 6348088 PMCID: PMC1129194 DOI: 10.1172/jci110979] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Insulin binds specifically to basolateral renal cortical membranes and modifies tubular electrolyte transport, but the target sites of this hormone in the nephron have not been identified. Using a microassay that permits measurement of hormone binding in discrete tubule segments we have determined the binding sites of 125I-insulin along the rabbit nephron. Assays were performed under conditions that minimize insulin degradation, and specific binding was measured as the difference between 125I-insulin bound in the presence or absence of excess (10(-5) M) unlabeled hormone. Insulin monoiodinated in position A14 was used in all assays. Specific insulin binding (attomol . cm-1 +/- SE) was highest in the distal convoluted tubule (180.5 +/- 15.0) and medullary thick ascending limb of Henle's loop (132.9 +/- 14.6), followed by the proximal convoluted and straight tubule. When expressed per milligram protein, insulin binding capacity was highest along the entire thick ascending limb (medullary and cortical portions) and the distal convoluted tubule, i.e., the "diluting segment" (congruent to 10(-13) mol . mg protein-1), and was lower (congruent to 4 X 10(-14) mol . mg protein-1), and remarkably similar, in all other nephron segments. Binding specificity was verified in competition studies with unlabeled insulin, insulin analogues (proinsulin and desoctapeptide insulin), and unrelated hormones (glucagon, 1-34 parathyroid hormone, prolactin, follicle-stimulating hormone). In addition, serum containing antiinsulin receptor antibody from two patients with type B insulin resistance syndrome markedly inhibited insulin binding to isolated tubules. Whether calculated per unit tubule length or protein content, insulin binding is highest in the thick ascending limb and the distal convoluted tubule, the same nephron sites where a regulatory role in sodium transport has been postulated for this hormone.
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26
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Brazy PC, Gullans SR, Mandel LJ, Dennis VW. Metabolic requirement for inorganic phosphate by the rabbit proximal tubule. J Clin Invest 1982; 70:53-62. [PMID: 7085888 PMCID: PMC370226 DOI: 10.1172/jci110603] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
These studies examine the effects of acute changes in the availability of inorganic phosphate on the function of isolated proximal renal tubules from rabbit kidney. We removed phosphate from the extracellular fluids and measured fluid absorption rates in isolated perfused tubules and oxygen consumption rates in suspensions of cortical tubules. In proximal convoluted tubules, the selective removal of phosphate from the luminal fluid reduced fluid absorption rates from 1.11+/-0.12 to -0.01+/-0.08 nl/mm . min. This effect on fluid absorption was dependent on the presence of glucose transport and metabolism. The addition of phlorizin to the phosphate-free luminal fluid preserved fluid absorption rates (1.12+/-0.12 nl/mm . min) as did the substitution of nonmetabolized alpha-methyl d-glucopyranoside for glucose (1.05+/-0.21 nl/mm . min) or the addition of 2-deoxyglucose, an inhibitor of glycolysis, to the bathing medium (1.01+/-0.15 nl/mm . min). There was no effect on fluid absorption if phosphate was removed from the bath only. Additionally, removal of phosphate from the luminal fluid of proximal straight rather than convoluted tubules had no effect on fluid absorption rates. Oxygen consumption rates in suspensions of cortical tubules were reduced from 18.9+/-0.6 to 10.6+/-0.6 nmol O(2)/mg tubular protein . min by the removal of phosphate from the medium. This inhibition was prevented by the substitution of alpha-methyl d-glucopyranoside for glucose in the phosphate-free medium. The data indicate that under certain conditions, proximal convoluted tubules require the presence of phosphate in the luminal fluid to preserve tubular function. In the absence of intraluminal phosphate, glucose metabolism causes a reduction in both oxidative metabolism and fluid absorption. This response is analogous to the Crabtree effect and suggests limitations on the intracellular availability of inorganic phosphate.
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27
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Vandewalle A, Köpfer-Hobelsberger B, Heidrich HG. Cortical cell populations from rabbit kidney isolated by free-flow electrophoresis: characterization by measurement of hormone-sensitive adenylate cyclase. J Cell Biol 1982; 92:505-13. [PMID: 6277964 PMCID: PMC2112067 DOI: 10.1083/jcb.92.2.505] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Free-flow electrophoresis allows the separation of different cell populations from a cell suspension isolated from rabbit kidney cortex after perfusion of the kidneys with a calcium-binder, followed by gentle mechanical treatment. After electrophoretic separation, analysis of the adenylate cyclase activities after stimulation by various hormones allows the precise determination of the origin of the cell populations with different electrophoretic mobilities. Adenylate cyclase from the slow-moving main cell population was only sensitive to parathyroid hormone. These cells had also high alkaline phosphatase content, further demonstrating their proximal origin. The various fast-moving cell populations had adenylate cyclase sensitive to isoproterenol and arginine vasopressin but were less sensitive to parathyroid hormone than the slow-moving cells. Their alkaline phosphatase content was also much lower. This indicates that these fast-moving cell populations originate from both the granulous segment of the distal tubule and from the collecting ducts. The adenylate cyclase activity and the cyclic AMP contents of isolated proximal cells maintained in culture medium were also investigated.
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Wirthensohn G, Vandewalle A, Guder WG. Renal glycerol metabolism and the distribution of glycerol kinase in rabbit nephron. Biochem J 1981; 198:543-9. [PMID: 6275852 PMCID: PMC1163300 DOI: 10.1042/bj1980543] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Glycerol and dihydroxyacetone are metabolized by rabbit kidney-cortex tubules, isolated by collagenase treatment. Half-maximal concentrations of both substrates were determined with regard to uptake rates and product formations. Maximal uptake rates were 643 and 329 mumol/h per g of protein for dihydroxyacetone and glycerol respectively. Glucose and lactate were found as major metabolic products. Glycerol kinase, the enzyme catalysing the first step in renal glycerol and dihydroxyacetone metabolism, was measured radiochemically as described by Newsholme, Robinson & Taylor [(1967) Biochim, Biophys. Acta 132, 338-346] and adapted for studies of the localization of this enzyme along the different structures of rabbit nephron. The results show that glycerol kinase is located exclusively in the proximal segments, i.e. the proximal convoluted tubules and the pars recta, but is negligible in the other structures studied. The activities were close to the maximal dihydroxyacetone uptake rates measured in tubule suspensions.
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