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Hemha P, Chomphoo S, Polsan Y, Goto K, Watanabe M, Kondo H, Hipkaeo W. Discrete localization of phospholipase Cβ3 and diacylglycerol kinase ι along the renal proximal tubules of normal rat kidney and gentamicin-induced changes in their expression. Histochem Cell Biol 2023; 159:293-307. [PMID: 36478081 DOI: 10.1007/s00418-022-02166-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2022] [Indexed: 12/12/2022]
Abstract
Many signaling enzymes have multiple isozymes that are localized discretely at varying molecular levels in different compartments of cells where they play specific roles. In this study, among the various isozymes of phospholipase C (PLC) and diacylglycerol kinase (DGK), which work sequentially in the phosphoinositide cycle, both PLCβ3 and DGKι were found in renal brush-border microvilli, but found to replace each other along the proximal tubules: PLCβ3 in the proximal straight tubules (PST) of the outer stripe of the outer medulla (OSOM) and the medullary ray (MR), and DGKι in the proximal convoluted tubules (PCT) in the cortex and partially in the PST of the MR. Following daily injection of gentamicin for 1 week, the expression of PLCβ3 and DGKι was transiently enhanced, as demonstrated by western blot, and the increases were found to most likely occur in their original sites, that is, in the brush borders of the PST for PLCβ3 and in the PCT for DGKι. These findings showing differences in expression along the tubules suggest that the exertion of reabsorption and secretion through various ion channels and transporters in the microvillus membranes and the maintenance of microvillus turnover are regulated by a PLC-mediated signal with the balance shifted toward relative augmentation of the DAG function in the PST, and by a DGK-mediated signal with the balance shifted to relative augmentation of the phosphatidic acid function in the PCT. Our results also suggest the possibility that these isozymes are potential diagnostic signs for the early detection of acute kidney injury caused by gentamicin.
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Affiliation(s)
- Premrudee Hemha
- Electron Microscopy Laboratory, Division of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Surang Chomphoo
- Electron Microscopy Laboratory, Division of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Yada Polsan
- Electron Microscopy Laboratory, Division of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Kaoru Goto
- Department of Anatomy, School of Medicine, Yamagata University, Yamagata, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Hisatake Kondo
- Electron Microscopy Laboratory, Division of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Wiphawi Hipkaeo
- Electron Microscopy Laboratory, Division of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.
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Cleveland KH, Schnellmann RG. The β 2-adrenergic receptor agonist formoterol restores mitochondrial homeostasis in glucose-induced renal proximal tubule injury through separate integrated pathways. Biochem Pharmacol 2023; 209:115436. [PMID: 36720358 DOI: 10.1016/j.bcp.2023.115436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/19/2023] [Accepted: 01/23/2023] [Indexed: 01/31/2023]
Abstract
Mitochondrial dysfunction drives the development and progression of diabetic kidney disease (DKD). Previously, we discovered that the β2-adrenergic receptor (AR) agonist formoterol regulates mitochondrial dynamics in the hyperglycemic renal proximal tubule. The goal of this study was to identify signaling mechanisms through which formoterol restores the mitochondrial fission/fusion proteins Drp1 and Mfn1. Using primary renal proximal tubule cells (RPTC), the effect of chronic high glucose on RhoA/ROCK1/Drp1 and Raf/MEK1/2/ERK1/2/Mfn1 signaling was determined. In glucose-treated RPTC, RhoA became hyperactive, leading to ROCK1-induced activation of Drp1. Treatment with formoterol and/or pharmacological inhibitors targeting RhoA, ROCK1 and Drp1 blocked RhoA and Drp1 hyperactivity. Inhibiting this pathway also restored maximal mitochondrial respiration. By preventing Gβγ signaling with gallein, we determined that formoterol signals through the Gβγ subunit of the β2-AR to restore RhoA and Drp1. Furthermore, formoterol restored this pathway by blocking binding of RhoA with the guanine nucleotide exchange factor p114RhoGEF. Formoterol also restored the mitochondrial fusion protein Mfn1 through a second Gβγ-dependent mechanism composed of Raf/MEK1/2/ERK1/2/Mfn1. Glucose-treated RPTC exhibited decreased Mfn1 activity, which was restored with formoterol. Pharmacological inhibition of Gβγ, Raf and MEK1/2 also restored Mfn1 activity. We demonstrate that glucose promotes the interaction between RhoA and p114RhoGEF, leading to increased RhoA and ROCK1-mediated activation of Drp1, and decreases Mfn1 activity through Raf/MEK1/2/ERK1/2. Formoterol restores these pathways and mitochondrial function in response to elevated glucose by activating separate yet integrative pathways that promote mitochondrial biogenesis, decreased fission and increased fusion in RPTC, further supporting its potential as a therapeutic for DKD.
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Affiliation(s)
- Kristan H Cleveland
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, United States
| | - Rick G Schnellmann
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, United States; Southern Arizona VA Health Care System, Tucson, AZ, United States; Southwest Environmental Health Science Center, University of Arizona, Tucson, AZ, United States.
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Kobayashi M, Mizutani A, Okamoto T, Muranaka Y, Nishi K, Nishii R, Shikano N, Nakanishi T, Tamai I, Kleinerman ES, Kawai K. Assessment of drug transporters involved in the urinary secretion of [ 99mTc]dimercaptosuccinic acid. Nucl Med Biol 2021; 94-95:92-97. [PMID: 33609918 DOI: 10.1016/j.nucmedbio.2021.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/21/2021] [Accepted: 01/25/2021] [Indexed: 01/16/2023]
Abstract
INTRODUCTION We clarified the renal uptake and urinary secretion mechanism of [99mTc]dimercaptosuccinic acid ([99mTc]DMSA) via drug transporters in renal proximal tubules. METHODS [99mTc]DMSA was added to human embryonic kidney 293 cells expressing human multidrug and toxin extrusion (MATE)1 and MATE2-K, carnitine/organic cation transporter (OCTN)1 and OCTN2, and organic cation transporter (OCT)2; to Flp293 cells expressing human organic anion transporter (OAT)1 and OAT3; and to vesicles expressing P-glycoprotein (P-gp), multidrug resistance associated protein (MRP)2, MRP4, or breast cancer resistance protein with and without probenecid (OAT inhibitor for both OATs and MRPs). Time activity curves of [99mTc]DMSA with and without probenecid were established using LLC-PK1 cells. Biodistribution and single photon emission computed tomography (SPECT) imaging in mice were conducted using [99mTc]DMSA with and without probenecid. RESULTS [99mTc]DMSA uptake was significantly higher in Flp293/OAT3 than in mock cells. Uptake via OAT3 was inhibited by probenecid. [99mTc]DMSA uptake into vesicles that highly expressed MRP2 was significantly higher in adenosine triphosphate (ATP) than in adenosine monophosphate (AMP), and probenecid decreased uptake to similar levels as that in AMP. In the time activity curves for [99mTc]DMSA in LLC-PK1 cells, probenecid loading inhibited accumulation from the basolateral side into LLC-PK1 cells, whereas accumulation from the apical side into cells gradually increased. Transport of [99mTc]DMSA from both sides was low. Biodistribution and SPECT imaging studies showed that [99mTc]DMSA with probenecid loading resulted in significantly higher accumulation in blood, heart, liver, and bladder after [99mTc]DMSA injection compared with control mice. Probenecid induced significantly lower accumulation in the kidney after [99mTc]DMSA injection. CONCLUSIONS [99mTc]DMSA accumulates in renal proximal tubular epithelial cells from blood via OAT3 on the basolateral side, and then a small volume of [99mTc]DMSA will be excreted in urine via MRP2. ADVANCES IN KNOWLEDGE: [99mTc]DMSA accumulates via OAT3 in renal proximal tubular epithelial cells and is slightly excreted from the cells via MRP2. IMPLICATIONS FOR PATIENT CARE: [99mTc]DMSA may be useful for measuring renal transport function with OAT3 in patients.
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Affiliation(s)
- Masato Kobayashi
- School of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.
| | - Asuka Mizutani
- School of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Takaki Okamoto
- Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Yuka Muranaka
- Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Kodai Nishi
- Department of Radioisotope Medicine, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan
| | - Ryuichi Nishii
- Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Naoto Shikano
- Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ibaraki, Japan
| | - Takeo Nakanishi
- Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Ikumi Tamai
- School of Pharmaceutical Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Eugenie S Kleinerman
- Division of Pediatrics, University of Texas M.D. Anderson Cancer Center, Houston, USA
| | - Keiichi Kawai
- School of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan; Biomedical Imaging Research Center, University of Fukui, Fukui, Japan
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Zhang G, Zhang J, DeHoog RJ, Pennathur S, Anderton CR, Venkatachalam MA, Alexandrov T, Eberlin LS, Sharma K. DESI-MSI and METASPACE indicates lipid abnormalities and altered mitochondrial membrane components in diabetic renal proximal tubules. Metabolomics 2020; 16:11. [PMID: 31925564 PMCID: PMC7301343 DOI: 10.1007/s11306-020-1637-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 01/04/2020] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Diabetic kidney disease (DKD) is the most prevalent complication in diabetic patients, which contributes to high morbidity and mortality. Urine and plasma metabolomics studies have been demonstrated to provide valuable insights for DKD. However, limited information on spatial distributions of metabolites in kidney tissues have been reported. OBJECTIVES In this work, we employed an ambient desorption electrospray ionization-mass spectrometry imaging (DESI-MSI) coupled to a novel bioinformatics platform (METASPACE) to characterize the metabolome in a mouse model of DKD. METHODS DESI-MSI was performed for spatial untargeted metabolomics analysis in kidneys of mouse models (F1 C57BL/6J-Ins2Akita male mice at 17 weeks of age) of type 1 diabetes (T1D, n = 5) and heathy controls (n = 6). RESULTS Multivariate analyses (i.e., PCA and PLS-DA (a 2000 permutation test: P < 0.001)) showed clearly separated clusters for the two groups of mice on the basis of 878 measured m/z's in kidney cortical tissues. Specifically, mice with T1D had increased relative abundances of pseudouridine, accumulation of free polyunsaturated fatty acids (PUFAs), and decreased relative abundances of cardiolipins in cortical proximal tubules when compared with healthy controls. CONCLUSION Results from the current study support potential key roles of pseudouridine and cardiolipins for maintaining normal RNA structure and normal mitochondrial function, respectively, in cortical proximal tubules with DKD. DESI-MSI technology coupled with METASPACE could serve as powerful new tools to provide insight on fundamental pathways in DKD.
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Affiliation(s)
- Guanshi Zhang
- Center for Renal Precision Medicine, Division of Nephrology, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Audie L. Murphy Memorial VA Hospital, South Texas Veterans Health Care System, San Antonio, TX, USA
| | - Jialing Zhang
- Department of Chemistry, The University of Texas at Austin, Austin, TX, USA
| | - Rachel J DeHoog
- Department of Chemistry, The University of Texas at Austin, Austin, TX, USA
| | - Subramaniam Pennathur
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Christopher R Anderton
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA
| | | | - Theodore Alexandrov
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA
| | - Livia S Eberlin
- Department of Chemistry, The University of Texas at Austin, Austin, TX, USA
| | - Kumar Sharma
- Center for Renal Precision Medicine, Division of Nephrology, Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
- Audie L. Murphy Memorial VA Hospital, South Texas Veterans Health Care System, San Antonio, TX, USA.
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Abstract
Calcium kidney stones are common worldwide. Most are idiopathic and composed of calcium oxalate. Calcium phosphate is present in around 80% and may initiate stone formation. Stone production is multifactorial with a polygenic genetic contribution. Phosphaturia is found frequently among stone formers but until recently received scant attention. This review examines possible mechanisms for the phosphaturia and its relevance to stone formation from a wide angle. There is a striking lack of clinical data. Phosphaturia is associated, but not correlated, with hypercalciuria, increased 1,25 dihydroxy-vitamin D [1,25 (OH)2D], and sometimes evidence of disturbances in proximal renal tubular function. Phosphate reabsorption in the proximal renal tubules requires tightly regulated interaction of many proteins. Paracellular flow through intercellular tight junctions is the major route of phosphate absorption from the intestine and can be reduced therapeutically in hyperphosphatemic patients. In monogenic defects stones develop when phosphaturia is associated with hypercalciuria, generally explained by increased 1,25 (OH)2D production in response to hypophosphatemia. Calcification does not occur in disorders with increased FGF23 when phosphaturia occurs in isolation and 1,25 (OH)2D is suppressed. Candidate gene studies have identified mutations in the phosphate transporters, but in few individuals. One genome-wide study identified a polymorphism of the phosphate transporter gene SLC34A4 associated with stones. Others did not find mutations obviously linked to phosphate reabsorption. Future genetic studies should have a wide trawl and should focus initially on groups of patients with clearly defined phenotypes. The global data should be pooled.
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Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom.
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Abstract
The sorting and stabilization of proteins at specific subcellular domains depend upon the formation of networks build up by specific protein-protein interactions. In addition, protein networks also ensure the specificity of many regulatory processes by bringing together regulatory molecules with their targets. Whereas the success on the identification of protein-protein interactions is (up to a point) technology-driven, the assignment of functional roles to specific partners remains a major challenge. This review summarizes the work that led to the identification of partners of the Na+/phosphate cotransporter NaPi-IIa as well as the effects of the interactions in the expression and/or regulation of the cotransporter.
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Affiliation(s)
- Nati Hernando
- Institute of Physiology, University Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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Saidani C, Hammoudi-Triki D, Laraba-Djebari F, Taub M. In vitro studies with renal proximal tubule cells show direct cytotoxicity of Androctonus australis hector scorpion venom triggered by oxidative stress, caspase activation and apoptosis. Toxicon 2016; 120:29-37. [PMID: 27470530 DOI: 10.1016/j.toxicon.2016.07.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 07/13/2016] [Accepted: 07/20/2016] [Indexed: 01/20/2023]
Abstract
Scorpion envenomation injures a number of organs, including the kidney. Mechanisms proposed to explain the renal tubule injury include direct effects of venom on tubule epithelial cells, as well as indirect effects of the autonomic nervous system, and inflammation. Here, we report direct effects of Androctonus australis hector (Aah) scorpion venom on the viability of Renal Proximal Tubule (RPT) cells in vitro, unlike distal tubule and collecting duct cells. Extensive NucGreen nuclear staining was observed in immortalized rabbit RPT cells following treatment with Aah venom, consistent with cytotoxicity. The involvement of oxidative stress is supported by the observations that 1) anti-oxidants mitigated the Aah venom-induced decrease in the number of viable RPT cells, and 2) Aah venom-treated RPT cells were intensively stained with the CellROX(®) Deep Red reagent, an indicator of Reactive Oxygen Species (ROS). Relevance to normal RPT cells is supported by the red fluorescence observed in Aah venom treated primary rabbit RPT cell cultures following their incubation with the Flica reagent (indicative of caspase activation and apoptosis), and the green fluorescence of Sytox Green (indicative of dead cells).
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Affiliation(s)
- Chanez Saidani
- Université des Sciences et de la Technologie Hourari Boumediene (USTHB), Faculty of Biological Sciences, Laboratory of Cellular and Molecular Biology, Department of Cellular and Molecular Biology, BP32, El Alia, Bab Ezzouar 16111, Algiers, Algeria
| | - Djelila Hammoudi-Triki
- Université des Sciences et de la Technologie Hourari Boumediene (USTHB), Faculty of Biological Sciences, Laboratory of Cellular and Molecular Biology, Department of Cellular and Molecular Biology, BP32, El Alia, Bab Ezzouar 16111, Algiers, Algeria
| | - Fatima Laraba-Djebari
- Université des Sciences et de la Technologie Hourari Boumediene (USTHB), Faculty of Biological Sciences, Laboratory of Cellular and Molecular Biology, Department of Cellular and Molecular Biology, BP32, El Alia, Bab Ezzouar 16111, Algiers, Algeria
| | - Mary Taub
- Biochemistry Department, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
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Taub M, Garimella S, Kim D, Rajkhowa T, Cutuli F. Renal proximal tubule Na,K-ATPase is controlled by CREB-regulated transcriptional coactivators as well as salt-inducible kinase 1. Cell Signal 2015; 27:2568-78. [PMID: 26432356 PMCID: PMC4696386 DOI: 10.1016/j.cellsig.2015.09.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 09/17/2015] [Accepted: 09/28/2015] [Indexed: 01/11/2023]
Abstract
Sodium reabsorption by the kidney is regulated by locally produced natriuretic and anti-natriuretic factors, including dopamine and norepinephrine, respectively. Previous studies indicated that signaling events initiated by these natriuretic and anti-natriuretic factors achieve their effects by altering the phosphorylation of Na,K-ATPase in the renal proximal tubule, and that protein kinase A (PKA) and calcium-mediated signaling pathways are involved. The same signaling pathways also control the transcription of the Na,K-ATPase β subunit gene atp1b1 in renal proximal tubule cells. In this report, evidence is presented that (1) both the recently discovered cAMP-regulated transcriptional coactivators (CRTCs) and salt-inducible kinase 1 (SIK1) contribute to the transcriptional regulation of atp1b1 in renal proximal tubule (RPT) cells and (2) renal effectors, including norepinephrine, dopamine, prostaglandins, and sodium, play a role. Exogenously expressed CRTCs stimulate atp1b1 transcription. Evidence for a role of endogenous CRTCs includes the loss of transcriptional regulation of atp1b1 by a dominant-negative CRTC, as well as by a CREB mutant, with an altered CRTC binding site. In a number of experimental systems, SIK phosphorylates CRTCs, which are then sequestered in the cytoplasm, preventing their nuclear effects. Consistent with such a role of SIK in primary RPT cells, atp1b1 transcription increased in the presence of a dominant-negative SIK1, and in addition, regulation by dopamine, norepinephrine, and monensin was disrupted by a dominant-negative SIK1. These latter observations can be explained if SIK1 is phosphorylated and inactivated in the presence of these renal effectors. Our results support the hypothesis that Na,K-ATPase in the renal proximal tubule is regulated at the transcriptional level via SIK1 and CRTCs by renal effectors, in addition to the previously reported control of the phosphorylation of Na,K-ATPase.
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Affiliation(s)
- Mary Taub
- Biochemistry Department,School of Medicine and Biomedical SciencesUniversity at Buffalo,140 Farber Hall, 3435 Main Street,Buffalo, NY 14214, USA.
| | - Sudha Garimella
- Biochemistry Department,School of Medicine and Biomedical SciencesUniversity at Buffalo,140 Farber Hall, 3435 Main Street,Buffalo, NY 14214, USA
| | - Dongwook Kim
- Biochemistry Department,School of Medicine and Biomedical SciencesUniversity at Buffalo,140 Farber Hall, 3435 Main Street,Buffalo, NY 14214, USA
| | - Trivikram Rajkhowa
- Biochemistry Department,School of Medicine and Biomedical SciencesUniversity at Buffalo,140 Farber Hall, 3435 Main Street,Buffalo, NY 14214, USA
| | - Facundo Cutuli
- Biochemistry Department,School of Medicine and Biomedical SciencesUniversity at Buffalo,140 Farber Hall, 3435 Main Street,Buffalo, NY 14214, USA
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Seki G, Nakamura M, Suzuki M, Satoh N, Horita S. Species differences in regulation of renal proximal tubule transport by certain molecules. World J Nephrol 2015; 4:307-312. [PMID: 25949945 PMCID: PMC4419141 DOI: 10.5527/wjn.v4.i2.307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 12/24/2014] [Accepted: 01/20/2015] [Indexed: 02/06/2023] Open
Abstract
Renal proximal tubules (PTs) play important roles in the regulation of acid/base, plasma volume and blood pressure. Recent studies suggest that there are substantial species differences in the regulation of PT transport. For example, thiazolidinediones (TZDs) are widely used for the treatment of type 2 diabetes mellitus, but the use of TZDs is associated with fluid overload. In addition to the transcriptional enhancement of sodium transport in distal nephrons, TZDs rapidly stimulate PT sodium transport via a non-genomic mechanism depending on peroxisome proliferator activated receptor γ/Src/epidermal growth factor receptor (EGFR)/MEK/ERK. In mouse PTs, however, TZDs fail to stimulate PT transport probably due to constitutive activation of Src/EGFR/ERK pathway. This unique activation of Src/ERK may also affect the effect of high concentrations of insulin on mouse PT transport. On the other hand, the effect of angiotensin II (Ang II) on PT transport is known to be biphasic in rabbits, rats, and mice. However, Ang II induces a concentration-dependent, monophasic transport stimulation in human PTs. The contrasting responses to nitric oxide/guanosine 3’,5’-cyclic monophosphate pathway may largely explain these different effects of Ang II on PT transport. In this review, we focus on the recent findings on the species differences in the regulation of PT transport, which may help understand the species-specific mechanisms underlying edema formation and/or hypertension occurrence.
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