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Shi M, McCracken KW, Patel AB, Zhang W, Ester L, Valerius MT, Bonventre JV. Human ureteric bud organoids recapitulate branching morphogenesis and differentiate into functional collecting duct cell types. Nat Biotechnol 2023; 41:252-261. [PMID: 36038632 PMCID: PMC9957856 DOI: 10.1038/s41587-022-01429-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 07/13/2022] [Indexed: 12/29/2022]
Abstract
Directed differentiation of human pluripotent stem cells (hPSCs) into functional ureteric and collecting duct (CD) epithelia is essential to kidney regenerative medicine. Here we describe highly efficient, serum-free differentiation of hPSCs into ureteric bud (UB) organoids and functional CD cells. The hPSCs are first induced into pronephric progenitor cells at 90% efficiency and then aggregated into spheres with a molecular signature similar to the nephric duct. In a three-dimensional matrix, the spheres form UB organoids that exhibit branching morphogenesis similar to the fetal UB and correct distal tip localization of RET expression. Organoid-derived cells incorporate into the UB tips of the progenitor niche in chimeric fetal kidney explant culture. At later stages, the UB organoids differentiate into CD organoids, which contain >95% CD cell types as estimated by single-cell RNA sequencing. The CD epithelia demonstrate renal electrophysiologic functions, with ENaC-mediated vectorial sodium transport by principal cells and V-type ATPase proton pump activity by FOXI1-induced intercalated cells.
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Affiliation(s)
- Min Shi
- Division of Renal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Division of Nephrology, Kidney Research Institute, West China Hospital of Sichuan University, Chengdu, China
| | - Kyle W McCracken
- Division of Renal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
- Division of Nephrology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
- Division of Nephrology, Center for Stem Cell and Organoid Medicine (CuSTOM), Cincinnati Children's Hospital Medical Center, Cincinnati, USA.
| | - Ankit B Patel
- Division of Renal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Weitao Zhang
- Division of Renal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Department of Urology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Lioba Ester
- Division of Renal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Department II of Internal Medicine, University of Cologne, Faculty of Medicine, and University Hospital Cologne, Cologne, Germany
| | - M Todd Valerius
- Division of Renal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
- Harvard Stem Cell Institute, Cambridge and Boston, Boston, MA, USA
| | - Joseph V Bonventre
- Division of Renal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
- Harvard Stem Cell Institute, Cambridge and Boston, Boston, MA, USA.
- Division of Engineering in Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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Klemens CA, Staruschenko A, Palygin O. The Mechanisms of Cellular Plasticity in Collecting Duct Cells: Intermediate Cell Type and Notch-mediated Transdifferentiation. FUNCTION (OXFORD, ENGLAND) 2021; 2:zqab032. [PMID: 34223174 PMCID: PMC8244659 DOI: 10.1093/function/zqab032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 01/06/2023]
Affiliation(s)
- Christine A Klemens
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA,Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI 53295, USA
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3
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Bird JD, Leacy JK, Foster GE, Rickards CA, Wilson RJA, O'Halloran KD, Jendzjowsky NG, Pentz BA, Byman BRM, Thrall SF, Skalk AL, Hewitt SA, Steinback CD, Burns D, Ondrus P, Day TA. Time course and magnitude of ventilatory and renal acid-base acclimatization following rapid ascent to and residence at 3,800 m over nine days. J Appl Physiol (1985) 2021; 130:1705-1715. [PMID: 33703943 PMCID: PMC11025293 DOI: 10.1152/japplphysiol.00973.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/05/2021] [Indexed: 11/22/2022] Open
Abstract
Rapid ascent to high altitude imposes an acute hypoxic and acid-base challenge, with ventilatory and renal acclimatization countering these perturbations. Specifically, ventilatory acclimatization improves oxygenation, but with concomitant hypocapnia and respiratory alkalosis. A compensatory, renally mediated relative metabolic acidosis follows via bicarbonate elimination, normalizing arterial pH(a). The time course and magnitude of these integrated acclimatization processes are highly variable between individuals. Using a previously developed metric of renal reactivity (RR), indexing the change in arterial bicarbonate concentration (Δ[HCO3-]a; renal response) over the change in arterial pressure of CO2 (Δ[Formula: see text]; renal stimulus), we aimed to characterize changes in RR magnitude following rapid ascent and residence at altitude. Resident lowlanders (n = 16) were tested at 1,045 m (day [D]0) prior to ascent, on D2 within 24 h of arrival, and D9 during residence at 3,800 m. Radial artery blood draws were obtained to measure acid-base variables: [Formula: see text], [HCO3-]a, and pHa. Compared with D0, [Formula: see text] and [HCO3-]a were lower on D2 (P < 0.01) and D9 (P < 0.01), whereas significant changes in pHa (P = 0.072) and RR (P = 0.056) were not detected. As pHa appeared fully compensated on D2 and RR did not increase significantly from D2 to D9, these data demonstrate renal acid-base compensation within 24 h at moderate steady-state altitude. Moreover, RR was strongly and inversely correlated with ΔpHa on D2 and D9 (r≤ -0.95; P < 0.0001), suggesting that a high-gain renal response better protects pHa. Our study highlights the differential time course, magnitude, and variability of integrated ventilatory and renal acid-base acclimatization following rapid ascent and residence at high altitude.NEW & NOTEWORTHY We assessed the time course, magnitude, and variability of integrated ventilatory and renal acid-base acclimatization with rapid ascent and residence at 3,800 m. Despite reductions in [Formula: see text] upon ascent, pHa was normalized within 24 h of arrival at 3,800 m through renal compensation (i.e., bicarbonate elimination). Renal reactivity (RR) was unchanged between days 2 and 9, suggesting a lack of plasticity at moderate steady-state altitude. RR was strongly correlated with ΔpHa, suggesting that a high-gain renal response better protects pHa.
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Affiliation(s)
- Jordan D Bird
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Jack K Leacy
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Sciences Centre, Fort Worth, Texas
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Nicholas G Jendzjowsky
- Division of Respiratory and Critical Care Physiology and Medicine, The Lundquist Institute for Biomedical Innovation, Harbor-UCLA Medical Center, Torrance, California
| | - Brandon A Pentz
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Britta R M Byman
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Scott F Thrall
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Alexandra L Skalk
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Sarah A Hewitt
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Craig D Steinback
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - David Burns
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Peter Ondrus
- Department of Family Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
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Assmus A, Mullins L, Ward M, Dobie R, Hunter R, Henderson NC, Mullins JJ. Loss of Adam10 Disrupts Ion Transport in Immortalized Kidney Collecting Duct Cells. FUNCTION 2021; 2:zqab024. [PMID: 34131651 PMCID: PMC8187228 DOI: 10.1093/function/zqab024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/23/2021] [Accepted: 04/27/2021] [Indexed: 01/06/2023] Open
Abstract
The kidney cortical collecting duct (CCD) comprises principal cells (PCs), intercalated cells (IC), and the recently discovered intermediate cell type. Kidney pathology in a mouse model of the syndrome of apparent aldosterone excess revealed plasticity of the CCD, with altered PC:intermediate cell:IC ratio. The self-immortalized mouse CCD cell line, mCCDcl1, shows functional characteristics of PCs, but displays a range of cell types, including intermediate cells, making it ideal to study plasticity. We knocked out Adam10, a key component of the Notch pathway, in mCCDcl1 cells, using CRISPR-Cas9 technology, and isolated independent clones, which exhibited severely affected sodium transport capacity and loss of aldosterone response. Single-cell RNA sequencing revealed significantly reduced expression of major PC-specific markers, such as Scnn1g (γ-ENaC) and Hsd11b2 (11βHSD2), but no significant changes in transcription of components of the Notch pathway were observed. Immunostaining in the knockout clone confirmed the decrease in expression of γ-ENaC and importantly, showed an altered, diffuse distribution of PC and IC markers, suggesting altered trafficking in the Adam10 knockout clone as an explanation for the loss of polarization.
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Affiliation(s)
- Adrienne Assmus
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Linda Mullins
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Mairi Ward
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Ross Dobie
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Robert Hunter
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Neil C Henderson
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - John J Mullins
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh, Edinburgh EH16 4TJ, UK
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Saxena V, Gao H, Arregui S, Zollman A, Kamocka MM, Xuei X, McGuire P, Hutchens M, Hato T, Hains DS, Schwaderer AL. Kidney intercalated cells are phagocytic and acidify internalized uropathogenic Escherichia coli. Nat Commun 2021; 12:2405. [PMID: 33893305 PMCID: PMC8065053 DOI: 10.1038/s41467-021-22672-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 03/18/2021] [Indexed: 02/02/2023] Open
Abstract
Kidney intercalated cells are involved in acid-base homeostasis via vacuolar ATPase expression. Here we report six human intercalated cell subtypes, including hybrid principal-intercalated cells identified from single cell transcriptomics. Phagosome maturation is a biological process that increases in biological pathway analysis rank following exposure to uropathogenic Escherichia coli in two of the intercalated cell subtypes. Real time confocal microscopy visualization of murine renal tubules perfused with green fluorescent protein expressing Escherichia coli or pHrodo Green E. coli BioParticles demonstrates that intercalated cells actively phagocytose bacteria then acidify phagolysosomes. Additionally, intercalated cells have increased vacuolar ATPase expression following in vivo experimental UTI. Taken together, intercalated cells exhibit a transcriptional response conducive to the kidney's defense, engulf bacteria and acidify the internalized bacteria. Intercalated cells represent an epithelial cell with characteristics of professional phagocytes like macrophages.
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Affiliation(s)
- Vijay Saxena
- Indiana University School of Medicine, Department of Pediatrics, Division of Nephrology, Indianapolis, IN, USA.
| | - Hongyu Gao
- Indiana University School of Medicine, Department of Medical & Molecular Genetics, Indianapolis, IN, USA
| | - Samuel Arregui
- Indiana University School of Medicine, Department of Pediatrics, Division of Nephrology, Indianapolis, IN, USA
| | - Amy Zollman
- Indiana University School of Medicine, Department of Medicine, Division of Nephrology, Indianapolis, IN, USA
| | - Malgorzata Maria Kamocka
- Indiana University School of Medicine, Department of Medicine, Division of Nephrology, Indianapolis, IN, USA
| | - Xiaoling Xuei
- Indiana University School of Medicine, Department of Medical & Molecular Genetics, Indianapolis, IN, USA
| | - Patrick McGuire
- Indiana University School of Medicine, Department of Medical & Molecular Genetics, Indianapolis, IN, USA
| | - Michael Hutchens
- Oregon Health and Science University, Department of Anesthesiology & Perioperative Medicine, Portland, OR, USA
| | - Takashi Hato
- Indiana University School of Medicine, Department of Medicine, Division of Nephrology, Indianapolis, IN, USA
| | - David S Hains
- Indiana University School of Medicine, Department of Pediatrics, Division of Nephrology, Indianapolis, IN, USA
| | - Andrew L Schwaderer
- Indiana University School of Medicine, Department of Pediatrics, Division of Nephrology, Indianapolis, IN, USA.
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6
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Lipopolysaccharide directly inhibits bicarbonate absorption by the renal outer medullary collecting duct. Sci Rep 2020; 10:20548. [PMID: 33239624 PMCID: PMC7689453 DOI: 10.1038/s41598-020-77363-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/03/2020] [Indexed: 11/10/2022] Open
Abstract
Acidosis is associated with E. coli induced pyelonephritis but whether bacterial cell wall constituents inhibit HCO3 transport in the outer medullary collecting duct from the inner stripe (OMCDi) is not known. We examined the effect of lipopolysaccharide (LPS), on HCO3 absorption in isolated perfused rabbit OMCDi. LPS caused a ~ 40% decrease in HCO3 absorption, providing a mechanism for E. coli pyelonephritis-induced acidosis. Monophosphoryl lipid A (MPLA), a detoxified TLR4 agonist, and Wortmannin, a phosphoinositide 3-kinase inhibitor, prevented the LPS-mediated decrease, demonstrating the role of TLR4-PI3-kinase signaling and providing proof-of-concept for therapeutic interventions aimed at ameliorating OMCDi dysfunction and pyelonephritis-induced acidosis.
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7
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Zaidman NA, Tomilin VN, Hassanzadeh Khayyat N, Damarla M, Tidmore J, Capen DE, Brown D, Pochynyuk OM, Pluznick JL. Adhesion-GPCR Gpr116 (ADGRF5) expression inhibits renal acid secretion. Proc Natl Acad Sci U S A 2020; 117:26470-26481. [PMID: 33004624 PMCID: PMC7584995 DOI: 10.1073/pnas.2007620117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The diversity and near universal expression of G protein-coupled receptors (GPCR) reflects their involvement in most physiological processes. The GPCR superfamily is the largest in the human genome, and GPCRs are common pharmaceutical targets. Therefore, uncovering the function of understudied GPCRs provides a wealth of untapped therapeutic potential. We previously identified an adhesion-class GPCR, Gpr116, as one of the most abundant GPCRs in the kidney. Here, we show that Gpr116 is highly expressed in specialized acid-secreting A-intercalated cells (A-ICs) in the kidney using both imaging and functional studies, and we demonstrate in situ receptor activation using a synthetic agonist peptide unique to Gpr116. Kidney-specific knockout (KO) of Gpr116 caused a significant reduction in urine pH (i.e., acidification) accompanied by an increase in blood pH and a decrease in pCO2 compared to WT littermates. Additionally, immunogold electron microscopy shows a greater accumulation of V-ATPase proton pumps at the apical surface of A-ICs in KO mice compared to controls. Furthermore, pretreatment of split-open collecting ducts with the synthetic agonist peptide significantly inhibits proton flux in ICs. These data suggest a tonic inhibitory role for Gpr116 in the regulation of V-ATPase trafficking and urinary acidification. Thus, the absence of Gpr116 results in a primary excretion of acid in KO mouse urine, leading to mild metabolic alkalosis ("renal tubular alkalosis"). In conclusion, we have uncovered a significant role for Gpr116 in kidney physiology, which may further inform studies in other organ systems that express this GPCR, such as the lung, testes, and small intestine.
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Affiliation(s)
- Nathan A Zaidman
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Viktor N Tomilin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Naghmeh Hassanzadeh Khayyat
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Mahendra Damarla
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Josephine Tidmore
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Diane E Capen
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114
| | - Dennis Brown
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114
| | - Oleh M Pochynyuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Jennifer L Pluznick
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205;
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Li D, Snipes JA, Murea M, Molina AJA, Divers J, Freedman BI, Ma L, Petrovic S. An Acidic Environment Induces APOL1-Associated Mitochondrial Fragmentation. Am J Nephrol 2020; 51:695-704. [PMID: 32866949 DOI: 10.1159/000509989] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 07/03/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND Apolipoprotein L1 gene (APOL1) G1 and G2 kidney-risk variants (KRVs) cause CKD in African Americans, inducing mitochondrial dysfunction. Modifying factors are required, because a minority of individuals with APOL1 high-risk genotypes develop nephropathy. Given that APOL1 function is pH-sensitive and the pH of the kidney interstitium is <7, we hypothesized the acidic kidney interstitium may facilitate APOL1 KRV-induced mitochondrial dysfunction. METHODS Human embryonic kidney (HEK293) cells conditionally expressing empty vector (EV), APOL1-reference G0, and G1 or G2 KRVs were incubated in media pH 6.8 or 7.4 for 4, 6, or 8 h. Genotype-specific pH effects on mitochondrial length (µm) were assessed using confocal microscopy in live cells and Fiji derivative of ImageJ software with MiNA plug-in. Lower mitochondrial length indicated fragmentation and early dysfunction. RESULTS After 6 h doxycycline (Dox) induction in pH 6.8 media, G2-expressing cells had shorter mitochondria (6.54 ± 0.40) than cells expressing EV (7.65 ± 0.72, p = 0.02) or G0 (7.46 ± 0.31, p = 0.003). After 8 h Dox induction in pH 6.8 media, both G1- (6.21 ± 0.26) and G2-expressing cells had shorter mitochondria (6.46 ± 0.34) than cells expressing EV (7.13 ± 0.32, p = 0.002 and p = 0.008, respectively) or G0 (7.22 ± 0.45, p = 0.003 and p = 0.01, respectively). Mitochondrial length in cells incubated in pH 7.4 media were comparable after 8 h Dox induction regardless of genotype. APOL1 mRNA expression and cell viability were comparable regardless of pH or genotype after 8 h Dox induction. CONCLUSION Acidic pH facilitates early mitochondrial dysfunction induced by APOL1 G1 and G2 KRVs in HEK293 cells. We propose that the acidic kidney interstitium may play a role in APOL1-mediated mitochondrial pathophysiology and nephropathy.
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Affiliation(s)
- DengFeng Li
- Department of Biology, University of North Carolina at Greensboro, Greensboro, North Carolina, USA
- Department of Internal Medicine, Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - James A Snipes
- Department of Internal Medicine, Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Mariana Murea
- Department of Internal Medicine, Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Anthony J A Molina
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Jasmin Divers
- Division of Public Health Sciences, Department of Biostatistical Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Barry I Freedman
- Department of Internal Medicine, Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Lijun Ma
- Department of Internal Medicine, Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA,
| | - Snezana Petrovic
- Department of Internal Medicine, Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
- Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
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9
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Tong K, Hu Z. FOXI1 expression in chromophobe renal cell carcinoma and renal oncocytoma: a study of The Cancer Genome Atlas transcriptome-based outlier mining and immunohistochemistry. Virchows Arch 2020; 478:647-658. [PMID: 32812119 DOI: 10.1007/s00428-020-02900-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 07/19/2020] [Accepted: 08/06/2020] [Indexed: 01/09/2023]
Abstract
FOXI1 is a forkhead family transcription factor that plays a key role in differentiation and functional maintenance for the renal intercalated cell (IC). The diagnostic utility of FOXI1 is rarely studied thus far. Comparative analyses of FOXI1 mRNA expression in normal kidney tissue and different renal neoplasms including chromophobe renal cell carcinoma (chRCC), renal oncocytoma (RO), and other renal cell carcinomas were conducted using transcriptomic data from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus, and single-cell RNA-seq datasets, in combination with integrative analyses using mutant data, karyotype data, and digital slides for cases with anomalous FOXI1 expression in TCGA. Formalin-fixed, paraffin-embedded whole-tissue slides of varied primary renal neoplasms (n = 367) were subjected to FOXI1 staining for validating FOXI1 transcription levels. We confirmed that FOXI1 was significantly upregulated at mRNA levels in ICs, chRCCs, and ROs compared with other renal tubule cell and renal cell carcinoma subtypes. Furthermore, most of the cases with FOXI1 expression outliers were misclassified in the TCGA kidney cancer project. An underlying novel entity with frequent mutations involved in the mTOR pathway was also found. FOXI1 immunoreactivity was consistently noted in ICs of the distal nephron. FOXI1 staining was positive in 85 of 93 chRCCs and 13 of 18 ROs, respectively. FOXI1 staining was not seen in renal neoplasms (n = 254) derived from non-ICs. In conclusion, FOXI1 expression in normal kidney tissue is restricted to ICs. This cell type-specific expression is retained during neoplastic transformation from ICs to chRCCs or ROs. FOXI1 is thereby a potential biomarker of IC-related tumors.
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Affiliation(s)
- Kuo Tong
- Department of Pathology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, 410078, Hunan, China.,Department of Pathology, The Bishan Hospital of Chongqing, Bishan District, Chongqing, 402760, China.,Department of Pathology, School of Basic Medical Science, Central South University, 172 Tongzi Road, Changsha, 410013, Hunan, China
| | - Zhongliang Hu
- Department of Pathology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, 410078, Hunan, China. .,Department of Pathology, School of Basic Medical Science, Central South University, 172 Tongzi Road, Changsha, 410013, Hunan, China.
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10
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Wall SM, Verlander JW, Romero CA. The Renal Physiology of Pendrin-Positive Intercalated Cells. Physiol Rev 2020; 100:1119-1147. [PMID: 32347156 PMCID: PMC7474261 DOI: 10.1152/physrev.00011.2019] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 11/06/2019] [Accepted: 11/12/2019] [Indexed: 12/13/2022] Open
Abstract
Intercalated cells (ICs) are found in the connecting tubule and the collecting duct. Of the three IC subtypes identified, type B intercalated cells are one of the best characterized and known to mediate Cl- absorption and HCO3- secretion, largely through the anion exchanger pendrin. This exchanger is thought to act in tandem with the Na+-dependent Cl-/HCO3- exchanger, NDCBE, to mediate net NaCl absorption. Pendrin is stimulated by angiotensin II and aldosterone administration via the angiotensin type 1a and the mineralocorticoid receptors, respectively. It is also stimulated in models of metabolic alkalosis, such as with NaHCO3 administration. In some rodent models, pendrin-mediated HCO3- secretion modulates acid-base balance. However, of probably more physiological or clinical significance is the role of these pendrin-positive ICs in blood pressure regulation, which occurs, at least in part, through pendrin-mediated renal Cl- absorption, as well as their effect on the epithelial Na+ channel, ENaC. Aldosterone stimulates ENaC directly through principal cell mineralocorticoid hormone receptor (ligand) binding and also indirectly through its effect on pendrin expression and function. In so doing, pendrin contributes to the aldosterone pressor response. Pendrin may also modulate blood pressure in part through its action in the adrenal medulla, where it modulates the release of catecholamines, or through an indirect effect on vascular contractile force. In addition to its role in Na+ and Cl- balance, pendrin affects the balance of other ions, such as K+ and I-. This review describes how aldosterone and angiotensin II-induced signaling regulate pendrin and the contribution of pendrin-positive ICs in the kidney to distal nephron function and blood pressure.
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Affiliation(s)
- Susan M Wall
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
| | - Jill W Verlander
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
| | - Cesar A Romero
- Departments of Medicine and Physiology, Emory University School of Medicine, Atlanta, Georgia; and Department of Medicine, University of Florida, Gainesville, Florida
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11
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Zouboules SM, Lafave HC, O'Halloran KD, Brutsaert TD, Nysten HE, Nysten CE, Steinback CD, Sherpa MT, Day TA. Renal reactivity: acid-base compensation during incremental ascent to high altitude. J Physiol 2018; 596:6191-6203. [PMID: 30267579 DOI: 10.1113/jp276973] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 09/19/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Ascent to high altitude imposes an acid-base challenge in which renal compensation is integral for maintaining pH homeostasis, facilitating acclimatization and helping prevent mountain sicknesses. The time-course and extent of plasticity of this important renal response during incremental ascent to altitude is unclear. We created a novel index that accurately quantifies renal acid-base compensation, which may have laboratory, fieldwork and clinical applications. Using this index, we found that renal compensation increased and plateaued after 5 days of incremental altitude exposure, suggesting plasticity in renal acid-base compensation mechanisms. The time-course and extent of plasticity in renal responsiveness may predict severity of altitude illness or acclimatization at higher or more prolonged stays at altitude. ABSTRACT Ascent to high altitude, and the associated hypoxic ventilatory response, imposes an acid-base challenge, namely chronic hypocapnia and respiratory alkalosis. The kidneys impart a relative compensatory metabolic acidosis through the elimination of bicarbonate (HCO3 - ) in urine. The time-course and extent of plasticity of the renal response during incremental ascent is unclear. We developed an index of renal reactivity (RR), indexing the relative change in arterial bicarbonate concentration ([HCO3 - ]a ) (i.e. renal response) against the relative change in arterial pressure of CO2 ( P aC O 2 ) (i.e. renal stimulus) during incremental ascent to altitude ( Δ [ HC O 3 - ] a / Δ P aC O 2 ). We aimed to assess whether: (i) RR magnitude was inversely correlated with relative changes in arterial pH (ΔpHa ) with ascent and (ii) RR increased over time and altitude exposure (i.e. plasticity). During ascent to 5160 m over 10 days in the Nepal Himalaya, arterial blood was drawn from the radial artery for measurement of blood gas/acid-base variables in lowlanders at 1045/1400 m and after 1 night of sleep at 3440 m (day 3), 3820 m (day 5), 4240 m (day 7) and 5160 m (day 10) during ascent. At 3820 m and higher, RR significantly increased and plateaued compared to 3440 m (P < 0.04), suggesting plasticity in renal acid-base compensations. At all altitudes, we observed a strong negative correlation (r ≤ -0.71; P < 0.001) between RR and ΔpHa from baseline. Renal compensation plateaued after 5 days of altitude exposure, despite subsequent exposure to higher altitudes. The time-course, extent of plasticity and plateau in renal responsiveness may predict severity of altitude illness or acclimatization at higher or more prolonged stays at altitude.
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Affiliation(s)
- Shaelynn M Zouboules
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Hailey C Lafave
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | | | | | | | - Cassandra E Nysten
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Craig D Steinback
- Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | | | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
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12
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Adenylyl cyclase 6 is required for maintaining acid-base homeostasis. Clin Sci (Lond) 2018; 132:1779-1796. [PMID: 29941522 DOI: 10.1042/cs20180060] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 06/15/2018] [Accepted: 06/25/2018] [Indexed: 12/14/2022]
Abstract
Adenylyl cyclase (AC) isoform 6 (AC6) is highly expressed throughout the renal tubule and collecting duct (CD), catalyzes the synthesis of cAMP and contributes to various aspects of renal transport. Several proteins involved in acid-base homeostasis are regulated by cAMP. In the present study, we assess the relative contribution of AC6 to overall acid-base regulation using mice with global deletion of AC6 (AC6-/-) or newly generated mice lacking AC6 in the renal tubule and CD (AC6loxloxPax8Cre). Higher energy expenditure in AC6-/- relative to wild-type (WT) mice, was associated with lower urinary pH, mild alkalosis in conjunction with elevated blood HCO3- concentrations, and significantly higher renal abundance of the H+-ATPase B1 subunit. In contrast with WT mice, AC6-/- mice have a less pronounced increase in urinary pH after 8 days of HCO3- challenge, which is associated with increased blood pH and HCO3- concentrations. Immunohistochemistry demonstrated that AC6 was expressed in intercalated cells (IC), but subcellular distribution of the H+-ATPase B1 subunit, pendrin, and the anion exchangers 1 and 2 in AC6-/- mice was normal. In the AC6-/- mice, H+-ATPase B1 subunit levels after HCO3- challenge were greater, which correlated with a higher number of type A IC. In contrast with the AC6-/- mice, AC6loxloxPax8Cre mice had normal urinary pH under baseline conditions but higher blood HCO3- than controls after HCO3- challenge. In conclusion, AC6 is required for maintaining normal acid-base homeostasis and energy expenditure. Under baseline conditions, renal AC6 is redundant for acid-base balance but becomes important under alkaline conditions.
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13
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Himmel NJ, Wang Y, Rodriguez DA, Sun MA, Blount MA. Chronic lithium treatment induces novel patterns of pendrin localization and expression. Am J Physiol Renal Physiol 2018; 315:F313-F322. [PMID: 29667915 PMCID: PMC6139525 DOI: 10.1152/ajprenal.00065.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/04/2018] [Accepted: 04/12/2018] [Indexed: 12/25/2022] Open
Abstract
Prolonged lithium treatment is associated with various renal side effects and is known to induce inner medullary collecting duct (IMCD) remodeling. In animals treated with lithium, the fraction of intercalated cells (ICs), which are responsible for acid-base homeostasis, increases compared with renal principal cells (PCs). To investigate the intricacies of lithium-induced IMCD remodeling, male Sprague-Dawley rats were fed a lithium-enriched diet for 0,1, 2, 3, 6, 9, or 12 wk. Urine osmolality was decreased at 1 wk, and from 2 to 12 wk, animals were severely polyuric. After 6 wk of lithium treatment, approximately one-quarter of the cells in the initial IMCD expressed vacuolar H+-ATPase, an IC marker. These cells were localized in portions of the inner medulla, where ICs are not normally found. Pendrin, a Cl-/[Formula: see text] exchanger, is normally expressed only in two IC subtypes found in the convoluted tubule, the cortical collecting duct, and the connecting tubule. At 6 wk of lithium treatment, we observed various patterns of pendrin localization and expression in the rat IMCD, including a novel phenotype wherein pendrin was coexpressed with aquaporin-4. These observations collectively suggest that renal IMCD cell plasticity may play an important role in lithium-induced IMCD remodeling.
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Affiliation(s)
- Nathaniel J Himmel
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Yirong Wang
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Daniel A Rodriguez
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Michael A Sun
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Mitsi A Blount
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
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14
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Acute regulated expression of pendrin in human urinary exosomes. Pflugers Arch 2017; 470:427-438. [PMID: 28803436 DOI: 10.1007/s00424-017-2049-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/23/2017] [Accepted: 07/26/2017] [Indexed: 10/19/2022]
Abstract
It is well known that pendrin, an apical Cl-/HCO3-exchanger in type B intercalated cells, is modulated by chronic acid-base disturbances and electrolyte intake. To study this adaptation further at the acute level, we analyzed urinary exosomes from individuals subjected to oral acute acid, alkali, and NaCl loading. Acute oral NH4Cl loading (n = 8) elicited systemic acidemia with a drop in urinary pH and an increase in urinary NH4 excretion. Nadir urinary pH was achieved 5 h after NH4Cl loading. Exosomal pendrin abundance was dramatically decreased at 3 h after acid loading. In contrast, after acute equimolar oral NaHCO3 loading (n = 8), urinary and venous blood pH rose rapidly with a significant attenuation of urinary NH4 excretion. Alkali loading caused rapid upregulation of exosomal pendrin abundance at 1 h and normalized within 3 h of treatment. Equimolar NaCl loading (n = 6) did not alter urinary or venous blood pH or urinary NH4 excretion. However, pendrin abundance in urinary exosomes was significantly reduced at 2 h of NaCl ingestion with lowest levels observed at 4 h after treatment. In patients with inherited distal renal tubular acidosis (dRTA), pendrin abundance in urinary exosomes was greatly reduced and did not change upon oral NH4Cl loading. In summary, pendrin can be detected and quantified in human urinary exosomes by immunoblotting. Acid, alkali, and NaCl loadings cause acute changes in pendrin abundance in urinary exosomes within a few hours. Our data suggest that exosomal pendrin is a promising urinary biomarker for acute acid-base and volume status changes in humans.
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15
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Schwartz GJ, Gao X, Tsuruoka S, Purkerson JM, Peng H, D'Agati V, Picard N, Eladari D, Al-Awqati Q. SDF1 induction by acidosis from principal cells regulates intercalated cell subtype distribution. J Clin Invest 2015; 125:4365-74. [PMID: 26517693 DOI: 10.1172/jci80225] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 09/11/2015] [Indexed: 12/13/2022] Open
Abstract
The nephron cortical collecting duct (CCD) is composed of principal cells, which mediate Na, K, and water transport, and intercalated cells (ICs), which are specialized for acid-base transport. There are two canonical IC forms: acid-secreting α-ICs and HCO3-secreting β-ICs. Chronic acidosis increases α-ICs at the expense of β-ICs, thereby increasing net acid secretion by the CCD. We found by growth factor quantitative PCR array that acidosis increases expression of mRNA encoding SDF1 (or CXCL12) in kidney cortex and isolated CCDs from mouse and rabbit kidney cortex. Exogenous SDF1 or pH 6.8 media increased H+ secretion and decreased HCO3 secretion in isolated perfused rabbit CCDs. Acid-dependent changes in H+ and HCO3 secretion were largely blunted by AMD3100, which selectively blocks the SDF1 receptor CXCR4. In mice, diet-induced chronic acidosis increased α-ICs and decreased β-ICs. Additionally, IC-specific Cxcr4 deletion prevented IC subtype alterations and magnified metabolic acidosis. SDF1 was transcriptionally regulated and a target of the hypoxia-sensing transcription factor HIF1α. IC-specific deletion of Hif1a produced no effect on mice fed an acid diet, as α-ICs increased and β-ICs decreased similarly to that observed in WT littermates. However, Hif1a deletion in all CCD cells prevented acidosis-induced IC subtype distribution, resulting in more severe acidosis. Cultured principal cells exhibited an HIF1α-dependent increase of Sdf1 transcription in response to media acidification. Thus, our results indicate that principal cells respond to acid by producing SDF1, which then acts on adjacent ICs.
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MESH Headings
- Animals
- Cells, Cultured
- Chemokine CXCL12/biosynthesis
- Chemokine CXCL12/genetics
- Hydrogen-Ion Concentration
- Hypoxia-Inducible Factor 1, alpha Subunit/genetics
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Ion Transport/physiology
- Kidney Glomerulus/cytology
- Kidney Glomerulus/metabolism
- Kidney Tubules, Collecting/cytology
- Kidney Tubules, Collecting/metabolism
- Mice
- Mice, Transgenic
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Rabbits
- Receptors, CXCR4/genetics
- Receptors, CXCR4/metabolism
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16
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Wen D, Sansom SC. Physiological role of NBCe2 in the regulation of electrolyte transport in the distal nephron. Am J Physiol Renal Physiol 2015; 309:F489-91. [PMID: 26136555 DOI: 10.1152/ajprenal.00192.2015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 06/29/2015] [Indexed: 01/11/2023] Open
Abstract
The electrogenic Na(+)-HCO3 (-) cotransporter 2 (NBCe2) is a newly discovered protein in the distal nephron. Our understanding is minimal regarding its physiological role in renal electrolyte transport. In this mini-review, we summarize the potential function of NBCe2 in the regulation of blood pressure, acid-base, and K(+) and Ca(2+) transport in the distal nephron.
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Affiliation(s)
- Donghai Wen
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Steven C Sansom
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
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17
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Purkerson JM, Schwaderer AL, Nakamori A, Schwartz GJ. Distinct α-intercalated cell morphology and its modification by acidosis define regions of the collecting duct. Am J Physiol Renal Physiol 2015; 309:F464-73. [PMID: 26084929 DOI: 10.1152/ajprenal.00161.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 06/12/2015] [Indexed: 01/27/2023] Open
Abstract
During metabolic acidosis, the cortical collecting duct (CCD) of the rabbit reverses the polarity of bicarbonate flux from net secretion to net absorption, and this is accomplished by increasing the proton secretory rate by α-intercalated cells (ICs) and decreasing bicarbonate secretion by β-ICs. To better characterize dynamic changes in H(+)-secreting α-ICs, we examined their morphology in collecting ducts microdissected from kidneys of normal, acidotic, and recovering rabbits. α-ICs in defined axial regions varied in number and basolateral anion exchanger (AE)1 morphology, which likely reflects their relative activity and function along the collecting duct. Upon transition from CCD to outer medullary collecting duct from the outer stripe to the inner stripe, the number of α-ICs increases from 11.0 ± 1.2 to 15.4 ± 1.11 and to 32.0 ± 1.3 cells/200 μm, respectively. In the CCD, the basolateral structure defined by AE1 typically exhibited a pyramidal or conical shape, whereas in the medulla the morphology was elongated and shallow, resulting in a more rectangular shape. Furthermore, acidosis reversibly induced α-ICs in the CCD to acquire a more rectangular morphology concomitant with a transition from diffusely cytoplasmic to increased basolateral surface distribution of AE1 and apical polarization of B1-V-ATPase. The latter results are consistent with the supposition that morphological adaptation from the pyramidal to rectangular shape reflects a transition toward a more "active" configuration. In addition, α-ICs in the outer medullary collecting duct from the outer stripe exhibited cellular morphology strikingly similar to dendritic cells that may reflect a newly defined ancillary function in immune defense of the kidney.
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Affiliation(s)
- Jeffrey M Purkerson
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York; and
| | - Andrew L Schwaderer
- Department of Pediatrics and Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio
| | - Aya Nakamori
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York; and
| | - George J Schwartz
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York; and
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18
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Renal acid-base regulation: new insights from animal models. Pflugers Arch 2014; 467:1623-41. [PMID: 25515081 DOI: 10.1007/s00424-014-1669-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/16/2022]
Abstract
Because majority of biological processes are dependent on pH, maintaining systemic acid-base balance is critical. The kidney contributes to systemic acid-base regulation, by reabsorbing HCO3 (-) (both filtered by glomeruli and generated within a nephron) and acidifying urine. Abnormalities in those processes will eventually lead to a disruption in systemic acid-base balance and provoke metabolic acid-base disorders. Research over the past 30 years advanced our understanding on cellular and molecular mechanisms responsible for those processes. In particular, a variety of transgenic animal models, where target genes are deleted either globally or conditionally, provided significant insights into how specific transporters are contributing to the renal acid-base regulation. Here, we broadly overview the mechanisms of renal ion transport participating to acid-base regulation, with emphasis on data obtained from transgenic mice models.
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19
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Purkerson JM, Heintz EV, Nakamori A, Schwartz GJ. Insights into acidosis-induced regulation of SLC26A4 (pendrin) and SLC4A9 (AE4) transporters using three-dimensional morphometric analysis of β-intercalated cells. Am J Physiol Renal Physiol 2014; 307:F601-11. [PMID: 24990900 DOI: 10.1152/ajprenal.00404.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The purpose of this study was to examine the three-dimensional (3-D) expression and distribution of anion transporters pendrin (SLC26A4) and anion exchanger (AE)4 (SLC4A9) in β-intercalated cells (β-ICs) of the rabbit cortical collecting duct (CCD) to better characterize the adaptation to acid-base disturbances. Confocal analysis and 3-D reconstruction of β-ICs, using identifiers of the nucleus and zona occludens, permitted the specific orientation of cells from normal, acidotic, and recovering rabbits, so that adaptive changes could be quantified and compared. The pendrin cap likely mediates apical Cl(-)/HCO3 (-) exchange, but it was also found beneath the zona occludens and in early endosomes, some of which may recycle back to the apical membrane via Rab11a(+) vesicles. Acidosis reduced the size of the pendrin cap, observed as a large decrease in cap volume above and below the zona occludens, and the volume of the Rab11a(+) apical recycling compartment. Correction of the acidosis over 12-18 h reversed these changes. Consistent with its proposed function in the basolateral exit of Na(+) via Na(+)-HCO3 (-) cotransport, AE4 was expressed as a barrel-like structure in the lateral membrane of β-ICs. Acidosis reduced AE4 expression in β-ICs, but this was rapidly reversed during the recovery from acidosis. The coordinate regulation of pendrin and AE4 during acidosis and recovery is likely to affect the magnitude of acid-base and possibly Na(+) transport across the CCD. In conclusion, acidosis induces a downregulation of AE expression in β-ICs and a diminished presence of pendrin in apical recycling endosomes.
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Affiliation(s)
- Jeffrey M Purkerson
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York
| | - Eric V Heintz
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York
| | - Aya Nakamori
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York
| | - George J Schwartz
- Department of Pediatrics, University of Rochester Medical Center, Rochester, New York
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20
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Direct physical contact between intercalated cells in the distal convoluted tubule and the afferent arteriole in mouse kidneys. PLoS One 2013; 8:e70898. [PMID: 24039709 PMCID: PMC3764123 DOI: 10.1371/journal.pone.0070898] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/28/2013] [Indexed: 11/19/2022] Open
Abstract
Recent physiological studies in the kidney proposed the existence of a secondary feedback mechanism termed ‘crosstalk’ localized after the macula densa. This newly discovered crosstalk contact between the nephron tubule and its own afferent arteriole may potentially revolutionize our understanding of renal vascular resistance and electrolyte regulation. However, the nature of such a crosstalk mechanism is still debated due to a lack of direct and comprehensive morphological evidence. Its exact location along the nephron, its prevalence among the different types of nephrons, and the type of cells involved are yet unknown. To address these issues, computer assisted 3-dimensional nephron tracing was applied in combination with direct immunohistochemistry on plastic sections and electron microscopy. ‘Random’ contacts in the cortex were identified by the tracing and excluded. We investigated a total of 168 nephrons from all cortical regions. The results demonstrated that the crosstalk contact existed, and that it was only present in certain nephrons (90% of the short-looped and 75% of the long-looped nephrons). The crosstalk contacts always occurred at a specific position – the last 10% of the distal convoluted tubule. Importantly, we demonstrated, for the first time, that the cells found in the tubule wall at the contact site were always type nonA-nonB intercalated cells. In conclusion, the present work confirmed the existence of a post macula densa physical crosstalk contact.
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21
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Peti-Peterdi J. Mitochondrial TCA cycle intermediates regulate body fluid and acid-base balance. J Clin Invest 2013; 123:2788-90. [PMID: 23926603 DOI: 10.1172/jci68095] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Intrarenal control mechanisms play an important role in the maintenance of body fluid and electrolyte balance and pH homeostasis. Recent discoveries of new ion transport and regulatory pathways in the distal nephron and collecting duct system have helped to better our understanding of these critical kidney functions and identified new potential therapeutic targets and approaches. In this issue of the JCI, Tokonami et al. report on the function of an exciting new paracrine mediator, the mitochondrial the citric acid(TCA) cycle intermediate α-ketoglutarate (αKG), which via its OXGR1 receptor plays an unexpected, nontraditional role in the adaptive regulation of renal HCO(3⁻) secretion and salt reabsorption.
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Affiliation(s)
- János Peti-Peterdi
- Department of Physiology and Biophysics and Department of Medicine, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California, 90033 USA.
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22
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Vijayakumar S, Peng H, Schwartz GJ. Galectin-3 mediates oligomerization of secreted hensin using its carbohydrate-recognition domain. Am J Physiol Renal Physiol 2013; 305:F90-9. [PMID: 23657851 DOI: 10.1152/ajprenal.00498.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A multidomain, multifunctional 230-kDa extracellular matrix (ECM) protein, hensin, regulates the adaptation of rabbit kidney to metabolic acidosis by remodeling collecting duct intercalated cells. Conditional deletion of hensin in intercalated cells of the mouse kidney leads to distal renal tubular acidosis and to a significant reduction in the number of cells expressing the basolateral chloride-bicarbonate exchanger kAE1, a characteristic marker of α-intercalated cells. Although hensin is secreted as a monomer, its polymerization and ECM assembly are essential for its role in the adaptation of the kidney to metabolic acidosis. Galectin-3, a unique lectin with specific affinity for β-galactoside glycoconjugates, directly interacts with hensin. Acidotic rabbits had a significant increase in the number of cells expressing galectin-3 in the collecting duct and exhibited colocalization of galectin-3 with hensin in the ECM of microdissected tubules. In this study, we confirmed the increased expression of galectin-3 in acidotic rabbit kidneys by real-time RT-PCR. Galectin-3 interacted with hensin in vitro via its carbohydrate-binding COOH-terminal domain, and the interaction was competitively inhibited by lactose, removal of the COOH-terminal domain of galectin-3, and deglycosylation of hensin. Galectin-9, a lectin with two carbohydrate-recognition domains, is also present in the rabbit kidney; galectin-9 partially oligomerized hensin in vitro. Our results demonstrate that galectin-3 plays a critical role in hensin ECM assembly by oligomerizing secreted monomeric hensin. Both the NH₂-terminal and COOH-terminal domains are required for this function. We suggest that in the case of galectin-3-null mice galectin-9 may partially substitute for the function of galectin-3.
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Affiliation(s)
- Soundarapandian Vijayakumar
- Department of Pediatrics (Pediatric Nephrology), University of Rochester School of Medicine, Rochester, NY, USA
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23
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Renal intercalated cells are rather energized by a proton than a sodium pump. Proc Natl Acad Sci U S A 2013; 110:7928-33. [PMID: 23610411 DOI: 10.1073/pnas.1221496110] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Na(+) concentration of the intracellular milieu is very low compared with the extracellular medium. Transport of Na(+) along this gradient is used to fuel secondary transport of many solutes, and thus plays a major role for most cell functions including the control of cell volume and resting membrane potential. Because of a continuous leak, Na(+) has to be permanently removed from the intracellular milieu, a process that is thought to be exclusively mediated by the Na(+)/K(+)-ATPase in animal cells. Here, we show that intercalated cells of the mouse kidney are an exception to this general rule. By an approach combining two-photon imaging of isolated renal tubules, physiological studies, and genetically engineered animals, we demonstrate that inhibition of the H(+) vacuolar-type ATPase (V-ATPase) caused drastic cell swelling and depolarization, and also inhibited the NaCl absorption pathway that we recently discovered in intercalated cells. In contrast, pharmacological blockade of the Na(+)/K(+)-ATPase had no effects. Basolateral NaCl exit from β-intercalated cells was independent of the Na(+)/K(+)-ATPase but critically relied on the presence of the basolateral ion transporter anion exchanger 4. We conclude that not all animal cells critically rely on the sodium pump as the unique bioenergizer, but can be replaced by the H(+) V-ATPase in renal intercalated cells. This concept is likely to apply to other animal cell types characterized by plasma membrane expression of the H(+) V-ATPase.
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24
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Sousa JF, Ham AJL, Whitwell C, Nam KT, Lee HJ, Yang HK, Kim WH, Zhang B, Li M, LaFleur B, Liebler DC, Goldenring JR. Proteomic profiling of paraffin-embedded samples identifies metaplasia-specific and early-stage gastric cancer biomarkers. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:1560-72. [PMID: 22944598 PMCID: PMC3483808 DOI: 10.1016/j.ajpath.2012.07.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 06/18/2012] [Accepted: 07/05/2012] [Indexed: 12/17/2022]
Abstract
Early diagnosis and curative resection are the predominant factors associated with increased survival in patients with gastric cancer. However, most gastric cancer cases are still diagnosed at later stages. Since most pathologic specimens are archived as FFPE samples, the ability to use them to generate expression profiles can greatly improve cancer biomarker discovery. We sought to uncover new biomarkers for stomach preneoplastic metaplasias and neoplastic lesions by generating proteome profiles using FFPE samples. We combined peptide isoelectric focusing and liquid chromatography-tandem mass spectrometry analysis to generate proteomic profiles from FFPE samples of intestinal-type gastric cancer, metaplasia, and normal mucosa. The expression patterns of selected proteins were analyzed by immunostaining first in single tissue sections from normal stomach, metaplasia, and gastric cancer and later in larger tissue array cohorts. We detected 60 proteins up-regulated and 87 proteins down-regulated during the progression from normal mucosa to metaplasia to gastric cancer. Two of the up-regulated proteins, LTF and DMBT1, were validated as specific markers for spasmolytic polypeptide-expressing metaplasia and intestinal metaplasia, respectively. In cancers, significantly lower levels of DMBT1 or LTF correlated with more advanced disease and worse prognosis. Thus, proteomic profiling using FFPE samples has led to the identification of two novel markers for stomach metaplasias and gastric cancer prognosis.
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Affiliation(s)
- Josane F. Sousa
- Nashville Veterans Affairs Medical Center and the Epithelial Biology Center and the Section of Surgical Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Amy-Joan L. Ham
- Department of Biochemistry, Jim Ayers Institute for Precancer Detection and Diagnosis, Vanderbilt University, Nashville, Tennessee
- Department of Pharmaceutical, Social, and Administrative Sciences, Belmont University College of Pharmacy, Nashville, Tennessee
| | - Corbin Whitwell
- Department of Biochemistry, Jim Ayers Institute for Precancer Detection and Diagnosis, Vanderbilt University, Nashville, Tennessee
| | - Ki Taek Nam
- Nashville Veterans Affairs Medical Center and the Epithelial Biology Center and the Section of Surgical Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Hyuk-Joon Lee
- Department of Surgery, Seoul National University College of Medicine, Seoul, Korea
- Cancer Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Han-Kwang Yang
- Department of Surgery, Seoul National University College of Medicine, Seoul, Korea
- Cancer Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Woo Ho Kim
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
- Cancer Research Institute, Seoul National University College of Medicine, Seoul, South Korea
| | - Bing Zhang
- Department of Biomedical Informatics, Vanderbilt University, Nashville, Tennessee
| | - Ming Li
- Division of Cancer Biostatistics, Vanderbilt University, Nashville, Tennessee
| | - Bonnie LaFleur
- Division of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson, Arizona
| | - Daniel C. Liebler
- Department of Biochemistry, Jim Ayers Institute for Precancer Detection and Diagnosis, Vanderbilt University, Nashville, Tennessee
| | - James R. Goldenring
- Nashville Veterans Affairs Medical Center and the Epithelial Biology Center and the Section of Surgical Sciences, Vanderbilt University School of Medicine, Nashville, Tennessee
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25
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Welsh-Bacic D, Nowik M, Kaissling B, Wagner CA. Proliferation of acid-secretory cells in the kidney during adaptive remodelling of the collecting duct. PLoS One 2011; 6:e25240. [PMID: 22039408 PMCID: PMC3200326 DOI: 10.1371/journal.pone.0025240] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 08/29/2011] [Indexed: 01/07/2023] Open
Abstract
The renal collecting duct adapts to changes in acid-base metabolism by remodelling and altering the relative number of acid or alkali secreting cells, a phenomenon termed plasticity. Acid secretory A intercalated cells (A-IC) express apical H(+)-ATPases and basolateral bicarbonate exchanger AE1 whereas bicarbonate secretory B intercalated cells (B-IC) express basolateral (and apical) H(+)-ATPases and the apical bicarbonate exchanger pendrin. Intercalated cells were thought to be terminally differentiated and unable to proliferate. However, a recent report in mouse kidney suggested that intercalated cells may proliferate and that this process is in part dependent on GDF-15. Here we extend these observations to rat kidney and provide a detailed analysis of regional differences and demonstrate that differentiated A-IC proliferate massively during adaptation to systemic acidosis. We used markers of proliferation (PCNA, Ki67, BrdU incorporation) and cell-specific markers for A-IC (AE1) and B-IC (pendrin). Induction of remodelling in rats with metabolic acidosis (with NH(4)Cl for 12 hrs, 4 and 7 days) or treatment with acetazolamide for 10 days resulted in a larger fraction of AE1 positive cells in the cortical collecting duct. A large number of AE1 expressing A-IC was labelled with proliferative markers in the cortical and outer medullary collecting duct whereas no labeling was found in B-IC. In addition, chronic acidosis also increased the rate of proliferation of principal collecting duct cells. The fact that both NH(4)Cl as well as acetazolamide stimulated proliferation suggests that systemic but not urinary pH triggers this response. Thus, during chronic acidosis proliferation of AE1 containing acid-secretory cells occurs and may contribute to the remodelling of the collecting duct or replace A-IC due to a shortened life span under these conditions.
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Affiliation(s)
- Desa Welsh-Bacic
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Marta Nowik
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | | | - Carsten A. Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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26
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Abstract
The distal nephron plays a critical role in the renal control of homeostasis. Until very recently most studies focused on the control of Na(+), K(+), and water balance by principal cells of the collecting duct and the regulation of solute and water by hormones from the renin-angiotensin-aldosterone system and by antidiuretic hormone. However, recent studies have revealed the unexpected importance of renal intercalated cells, a subtype of cells present in the connecting tubule and collecting ducts. Such cells were thought initially to be involved exclusively in acid-base regulation. However, it is clear now that intercalated cells absorb NaCl and K(+) and hence may participate in the regulation of blood pressure and potassium balance. The second paradigm-challenging concept we highlight is the emerging importance of local paracrine factors that play a critical role in the renal control of water and electrolyte balance.
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Affiliation(s)
- Dominique Eladari
- Centre de Recherche des Cordeliers, Université Paris Descartes, INSERM UMRS 872, Equipe 3, F-75006, Paris, France; ,
- Université Pierre et Marie Curie, CNRS ERL7226, F-75006, Paris, France
- Département de Physiologie, Hôpital Européen Georges Pompidou, Assistance Publique-Hôpitaux de Paris, F-75015, Paris, France
| | - Régine Chambrey
- Centre de Recherche des Cordeliers, Université Paris Descartes, INSERM UMRS 872, Equipe 3, F-75006, Paris, France; ,
- Université Pierre et Marie Curie, CNRS ERL7226, F-75006, Paris, France
| | - Janos Peti-Peterdi
- Department of Physiology and Biophysics, Keck School of Medicine, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California 90033;
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27
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Quigley IK, Stubbs JL, Kintner C. Specification of ion transport cells in the Xenopus larval skin. Development 2011; 138:705-14. [PMID: 21266406 DOI: 10.1242/dev.055699] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Specialized epithelial cells in the amphibian skin play important roles in ion transport, but how they arise developmentally is largely unknown. Here we show that proton-secreting cells (PSCs) differentiate in the X. laevis larval skin soon after gastrulation, based on the expression of a `kidney-specific' form of the H(+)v-ATPase that localizes to the plasma membrane, orthologs of the Cl(-)/HCO(-)(3) antiporters ae1 and pendrin, and two isoforms of carbonic anhydrase. Like PSCs in other species, we show that the expression of these genes is likely to be driven by an ortholog of foxi1, which is also sufficient to promote the formation of PSC precursors. Strikingly, the PSCs form in the skin as two distinct subtypes that resemble the alpha- and beta-intercalated cells of the kidney. The alpha-subtype expresses ae1 and localizes H(+)v-ATPases to the apical plasma membrane, whereas the beta-subtype expresses pendrin and localizes the H(+)v-ATPase cytosolically or basolaterally. These two subtypes are specified during early PSC differentiation by a binary switch that can be regulated by Notch signaling and by the expression of ubp1, a transcription factor of the grainyhead family. These results have implications for how PSCs are specified in vertebrates and become functionally heterogeneous.
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Affiliation(s)
- Ian K Quigley
- The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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28
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Deletion of hensin/DMBT1 blocks conversion of beta- to alpha-intercalated cells and induces distal renal tubular acidosis. Proc Natl Acad Sci U S A 2010; 107:21872-7. [PMID: 21098262 DOI: 10.1073/pnas.1010364107] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Acid-base transport in the renal collecting tubule is mediated by two canonical cell types: the β-intercalated cell secretes HCO(3) by an apical Cl:HCO(3) named pendrin and a basolateral vacuolar (V)-ATPase. Acid secretion is mediated by the α-intercalated cell, which has an apical V-ATPase and a basolateral Cl:HCO(3) exchanger (kAE1). We previously suggested that the β-cell converts to the α-cell in response to acid feeding, a process that depended on the secretion and deposition of an extracellular matrix protein termed hensin (DMBT1). Here, we show that deletion of hensin from intercalated cells results in the absence of typical α-intercalated cells and the consequent development of complete distal renal tubular acidosis (dRTA). Essentially all of the intercalated cells in the cortex of the mutant mice are canonical β-type cells, with apical pendrin and basolateral or diffuse/bipolar V-ATPase. In the medulla, however, a previously undescribed cell type has been uncovered, which resembles the cortical β-intercalated cell in ultrastructure, but does not express pendrin. Polymerization and deposition of hensin (in response to acidosis) requires the activation of β1 integrin, and deletion of this gene from the intercalated cell caused a phenotype that was identical to the deletion of hensin itself, supporting its critical role in hensin function. Because previous studies suggested that the conversion of β- to α-intercalated cells is a manifestation of terminal differentiation, the present results demonstrate that this differentiation proceeds from HCO(3) secreting to acid secreting phenotypes, a process that requires deposition of hensin in the ECM.
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29
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Adaptation to metabolic acidosis and its recovery are associated with changes in anion exchanger distribution and expression in the cortical collecting duct. Kidney Int 2010; 78:993-1005. [PMID: 20592712 DOI: 10.1038/ki.2010.195] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
It is well known that acid/base disturbances modulate proton/bicarbonate transport in the cortical collecting duct. To study the adaptation further we measured the effect of three days of acidosis followed by the rapid recovery from this acidosis on the number and type of intercalated cells in the rabbit cortical collecting duct. Immunofluorescence was used to determine the expression of apical pendrin in β-intercalated cells and the basolateral anion exchanger (AE1) in α-intercalated cells. Acidosis resulted in decreased bicarbonate and increased proton secretion, which correlated with reduced pendrin expression and the number of pendrin-positive cells, as well as decreased pendrin mRNA and protein abundance in this nephron segment. There was a concomitant increase of basolateral AE1 and α-cell number. Intercalated cell proliferation did not seem to play a role in the adaptation to acidosis. Alkali loading for 6-20 h after acidosis doubled the bicarbonate secretory flux and reduced proton secretion. Pendrin and AE1 expression patterns returned to control levels, demonstrating that adaptive changes by intercalated cells are rapidly reversible. Thus, regulation of intercalated cell anion exchanger expression and distribution plays a key role in adaptation of the cortical collecting duct to perturbations of acid/base.
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30
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Brown D, Paunescu TG, Breton S, Marshansky V. Regulation of the V-ATPase in kidney epithelial cells: dual role in acid-base homeostasis and vesicle trafficking. ACTA ACUST UNITED AC 2009; 212:1762-72. [PMID: 19448085 DOI: 10.1242/jeb.028803] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The proton-pumping V-ATPase is a complex, multi-subunit enzyme that is highly expressed in the plasma membranes of some epithelial cells in the kidney, including collecting duct intercalated cells. It is also located on the limiting membranes of intracellular organelles in the degradative and secretory pathways of all cells. Different isoforms of some V-ATPase subunits are involved in the targeting of the proton pump to its various intracellular locations, where it functions in transporting protons out of the cell across the plasma membrane or acidifying intracellular compartments. The former process plays a critical role in proton secretion by the kidney and regulates systemic acid-base status whereas the latter process is central to intracellular vesicle trafficking, membrane recycling and the degradative pathway in cells. We will focus our discussion on two cell types in the kidney: (1) intercalated cells, in which proton secretion is controlled by shuttling V-ATPase complexes back and forth between the plasma membrane and highly-specialized intracellular vesicles, and (2) proximal tubule cells, in which the endocytotic pathway that retrieves proteins from the glomerular ultrafiltrate requires V-ATPase-dependent acidification of post-endocytotic vesicles. The regulation of both of these activities depends upon the ability of cells to monitor the pH and/or bicarbonate content of their extracellular environment and intracellular compartments. Recent information about these pH-sensing mechanisms, which include the role of the V-ATPase itself as a pH sensor and the soluble adenylyl cyclase as a bicarbonate sensor, will be addressed in this review.
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Affiliation(s)
- Dennis Brown
- Center for Systems Biology, Program in Membrane Biology/Nephrology Division, Massachusetts General Hospital, Boston, MA 02114, USA.
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31
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Peng H, Vijayakumar S, Schiene-Fischer C, Li H, Purkerson JM, Malesevic M, Liebscher J, Al-Awqati Q, Schwartz GJ. Secreted cyclophilin A, a peptidylprolyl cis-trans isomerase, mediates matrix assembly of hensin, a protein implicated in epithelial differentiation. J Biol Chem 2008; 284:6465-75. [PMID: 19112104 DOI: 10.1074/jbc.m808964200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Hensin is a rabbit ortholog of DMBT1, a multifunctional, multidomain protein implicated in the regulation of epithelial differentiation, innate immunity, and tumorigenesis. Hensin in the extracellular matrix (ECM) induced morphological changes characteristic of terminal differentiation in a clonal cell line (clone C) of rabbit kidney intercalated cells. Although hensin is secreted in monomeric and various oligomeric forms, only the polymerized ECM form is able to induce these phenotypic changes. Here we report that hensin secretion and matrix assembly were inhibited by the peptidylprolyl cis-trans isomerase (PPIase) inhibitors cyclosporin A (CsA) and a derivative of cyclosporin A with modifications in the d-Ser side chain (Cs9) but not by the calcineurin pathway inhibitor FK506. PPIase inhibition led to failure of hensin polymerization in the medium and ECM, plus the loss of apical cytoskeleton, apical microvilli, and the columnar epithelial shape of clone C cells. Cyclophilin A was produced and secreted into the media to a much greater extent than cyclophilins B and C. Our results also identified the direct CsA-sensitive interaction of cyclophilin A with hensin, suggesting that cyclophilin A is the PPIase that mediates the polymerization and matrix assembly of hensin. These results are significant because this is the first time a direct role of peptidylprolyl cis-trans isomerase activity has been implicated in the process of epithelial differentiation.
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Affiliation(s)
- Hu Peng
- Department of Pediatrics, University of Rochester School of Medicine, Rochester, New York 14642, USA
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32
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Duong Van Huyen JP, Cheval L, Bloch-Faure M, Belair MF, Heudes D, Bruneval P, Doucet A. GDF15 triggers homeostatic proliferation of acid-secreting collecting duct cells. J Am Soc Nephrol 2008; 19:1965-74. [PMID: 18650486 DOI: 10.1681/asn.2007070781] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Although adult kidney cells are quiescent, enlargement of specific populations of epithelial cells occurs during repair and adaptive processes. A prerequisite to the development of regenerative therapeutics is to identify the mechanisms and factors that control the size of specific populations of renal cells. Unfortunately, in most cases, it is unknown whether the growth of cell populations results from transdifferentiation or proliferation and whether proliferating cells derive from epithelial cells or from circulating or resident progenitors. In this study, the mechanisms underlying the enlargement of the acid-secreting cell population in the mouse kidney collecting duct in response to metabolic acidosis was investigated. Acidosis led to two phases of proliferation that preferentially affected the acid-secreting cells of the outer medullary collecting duct. All proliferating cells displayed polarized expression of functional markers. The first phase of proliferation, which started within 24 h and peaked at day 3, was dependent on the overexpression of growth differentiation factor 15 (GDF15) and cyclin D1 and was abolished when phosphatidylinositol-3 kinase and mammalian target of rapamycin were inhibited. During this phase, cells mostly divided along the tubular axis, contributing to tubule lengthening. The second phase of proliferation was independent of GDF15 but was associated with induction of cyclin D3. During this phase, cells divided transversely. In summary, acid-secreting cells proliferate as the collecting duct adapts to metabolic acidosis, and GDF15 seems to be an important determinant of collecting duct lengthening.
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Affiliation(s)
- Jean Paul Duong Van Huyen
- UPMC University of Paris 06, Unité Mixte de Recherche Scientifique UMRS 872, and INSERM, UMRS 872, Paris France
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33
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Vijayakumar S, Erdjument-Bromage H, Tempst P, Al-Awqati Q. Role of integrins in the assembly and function of hensin in intercalated cells. J Am Soc Nephrol 2008; 19:1079-91. [PMID: 18337486 DOI: 10.1681/asn.2007070737] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epithelial differentiation proceeds in at least two steps: Conversion of a nonepithelial cell into an epithelial sheet followed by terminal differentiation into the mature epithelial phenotype. It was recently discovered that the extracellular matrix (ECM) protein hensin is able to convert a renal intercalated cell line from a flat, squamous shape into a cuboidal or columnar epithelium. Global knockout of hensin in mice results in embryonic lethality at the time that the first columnar cells appear. Here, antibodies that either activate or block integrin beta1 were used to demonstrate that activation of integrin alpha v beta 1 causes deposition of hensin in the ECM. Once hensin polymerizes and deposits into the ECM, it binds to integrin alpha 6 and mediates the conversion of epithelial cells to a cuboidal phenotype capable of apical endocytosis; therefore, multiple integrins play a role in the terminal differentiation of the intercalated cell: alpha v beta 1 generates polymerized hensin, and another set of integrins (containing alpha 6) mediates signals between hensin and the interior of the cells.
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Affiliation(s)
- Soundarapandian Vijayakumar
- Pediatric Nephrology, University of Rochester Medical Center, 601 Elmwood Avenue, Box 777, Rochester, NY 14642, USA.
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34
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Wehrli P, Loffing-Cueni D, Kaissling B, Loffing J. Replication of segment-specific and intercalated cells in the mouse renal collecting system. Histochem Cell Biol 2006; 127:389-98. [PMID: 17186265 DOI: 10.1007/s00418-006-0261-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2006] [Indexed: 01/28/2023]
Abstract
The renal collecting system (CS) is composed of segment-specific (SS) and intercalated (IC) cells. The latter comprise at least two subtypes (type A and non-type A IC). The origin and maintenance of cellular heterogeneity in the CS is unclear. Among other hypotheses, it was proposed that one subtype of IC cells represents a stem cell population from which all cell types in the CS may arise. In the present study, we tested this stem cell hypothesis for the adult kidney by assessing DNA synthesis as a marker for cell replication. SS and IC cells were identified by their characteristic expressions of sodium- (epithelial sodium channel, Na-K-ATPase), water- (aquaporin-2) and acid/base- (H+ -ATPase, anion exchanger AE1) transporting proteins. Immunostaining for bromodeoxyuridine (BrdU) and for the proliferating cell nuclear antigen (PCNA) was used to reveal DNA synthesis in CS epithelium. BrdU- and PCNA-immunostaining as well as mitotic figures were seen in all subtypes of CS cells. Dividing cells retained the cell-type specific expression of marker molecules. Treatment of mice with bumetanide combined with a high oral salt intake, which increases the tubular salt load in the CS, profoundly increased the DNA-synthesis rate in SS and non-type A IC cells, but reduced it in type A IC cells. Thus, our data show that DNA synthesis and cell replication occur in each cell lineage of the CS and in differentiated cells. The replication rate in each cell type can be differently modulated by functional stimulation. Independent proliferation of each cell lineage might contribute to maintain the cellular heterogeneity of the CS of the adult kidney and may also add to the adaptation of the CS to altered functional requirements.
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Affiliation(s)
- Philipp Wehrli
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
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35
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Ring T, Frische S, Nielsen S. Clinical review: Renal tubular acidosis--a physicochemical approach. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2005; 9:573-80. [PMID: 16356241 PMCID: PMC1414010 DOI: 10.1186/cc3802] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The Canadian physiologist PA Stewart advanced the theory that the proton concentration, and hence pH, in any compartment is dependent on the charges of fully ionized and partly ionized species, and on the prevailing CO2 tension, all of which he dubbed independent variables. Because the kidneys regulate the concentrations of the most important fully ionized species ([K+], [Na+], and [Cl-]) but neither CO2 nor weak acids, the implication is that it should be possible to ascertain the renal contribution to acid–base homeostasis based on the excretion of these ions. One further corollary of Stewart's theory is that, because pH is solely dependent on the named independent variables, transport of protons to and from a compartment by itself will not influence pH. This is apparently in great contrast to models of proton pumps and bicarbonate transporters currently being examined in great molecular detail. Failure of these pumps and cotransporters is at the root of disorders called renal tubular acidoses. The unquestionable relation between malfunction of proton transporters and renal tubular acidosis represents a problem for Stewart theory. This review shows that the dilemma for Stewart theory is only apparent because transport of acid–base equivalents is accompanied by electrolytes. We suggest that Stewart theory may lead to new questions that must be investigated experimentally. Also, recent evidence from physiology that pH may not regulate acid–base transport is in accordance with the concepts presented by Stewart.
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Affiliation(s)
- Troels Ring
- Department of Nephrology, Aalborg Hospital, Aalborg, Denmark.
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36
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Friedlander G. [Dark cells: the endless story]. Med Sci (Paris) 2005; 21:655-7. [PMID: 15985211 DOI: 10.1051/medsci/2005216-7655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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37
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Takito J, Al-Awqati Q. Conversion of ES cells to columnar epithelia by hensin and to squamous epithelia by laminin. ACTA ACUST UNITED AC 2004; 166:1093-102. [PMID: 15452149 PMCID: PMC2172027 DOI: 10.1083/jcb.200405159] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Single-layered epithelia are the first differentiated cell types to develop in the embryo, with columnar and squamous types appearing immediately after blastocyst implantation. Here, we show that mouse embryonic stem cells seeded on hensin or laminin, but not fibronectin or collagen type IV, formed hemispheric epithelial structures whose outermost layer terminally differentiated to an epithelium that resembled the visceral endoderm. Hensin induced columnar epithelia, whereas laminin formed squamous epithelia. At the egg cylinder stage, the distal visceral endoderm is columnar, and these cells begin to migrate anteriorly to create the anterior visceral endoderm, which assumes a squamous shape. Hensin expression coincided with the dynamic appearance and disappearance of columnar cells at the egg cylinder stage of the embryo. These expression patterns, and the fact that hensin null embryos (and those already reported for laminin) die at the onset of egg cylinder formation, support the view that hensin and laminin are required for terminal differentiation of columnar and squamous epithelial phenotypes during early embryogenesis.
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Affiliation(s)
- Jiro Takito
- Dept. of Medicine, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, USA
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38
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Al-Awqati Q, Schwartz GJ. A fork in the road of cell differentiation in the kidney tubule. J Clin Invest 2004; 113:1528-30. [PMID: 15173877 PMCID: PMC419498 DOI: 10.1172/jci22029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The collecting ducts of the kidney are composed of intercalated cells (responsible for acid/base transport), principal cells (mediating salt and water absorption), and inner medullary cells, which mediate all three types of transport. Forkhead box (Fox) genes are a large family of transcription factors that are important in cell-type specification during organogenesis. In this issue, Blomqvist et al. find that mice lacking Foxi1 have no intercalated cells in the kidney. The collecting ducts of the null mice contained primitive cells that expressed both intercalated cell and principal cell proteins, yet the acid/base transport function of the kidney was disrupted and the mice exhibited distal renal tubular acidosis. These findings suggest that Foxi1 plays a critical role in determining cell identity during collecting duct development.
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Affiliation(s)
- Qais Al-Awqati
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
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39
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Leniger T, Thöne J, Wiemann M. Topiramate modulates pH of hippocampal CA3 neurons by combined effects on carbonic anhydrase and Cl-/HCO3- exchange. Br J Pharmacol 2004; 142:831-42. [PMID: 15197104 PMCID: PMC1575064 DOI: 10.1038/sj.bjp.0705850] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Topiramate (TPM) is an anticonvulsant whose impact on firing activity and intracellular pH (pHi) regulation of CA3 neurons was investigated. Using the 4-aminopyridine-treated hippocampal slice model bathed in bicarbonate-buffered solution, TPM (25-50 microm) reduced the frequency of epileptiform bursts and action potentials without affecting membrane potential or input resistance. Inhibitory effects of TPM were reversed by trimethylamine-induced alkalinization. TPM also lowered the steady-state pHi of BCECF-AM-loaded neuronal somata by 0.18+/-0.07 pH units in CO(2)/HCO(3)(-)-buffered solution. Subsequent to an ammonium prepulse, TPM reduced the acidotic peak but clearly slowed pHi recovery. These complex changes were mimicked by the protein phosphatase inhibitor okadaic acid. Alkalosis upon withdrawal of extracellular Cl(-) was augmented by TPM. Furthermore, at decreased pHi due to the absence of extracellular Na(+), TPM reversibly increased pHi. These findings demonstrate that TPM modulates Na(+)-independent Cl(-)/HCO(3)(-) exchange. In the nominal absence of extracellular CO(2)/HCO(3)(-) buffer, both steady-state pHi and firing of epileptiform bursts remained unchanged upon adding TPM. However, pHi recovery subsequent to an ammonium prepulse was slightly increased, as was the case in the presence of the carbonic anhydrase (CA) inhibitor acetazolamide. Thus, a slight reduction of intracellular buffer capacity by TPM may be due to an inhibitory effect on intracellular CA. Together, these findings show that TPM lowers neuronal pHi most likely due to a combined effect on Na(+)-independent Cl(-)/HCO(3)(-) exchange and CA. The apparent decrease of steady-state pHi may contribute to the anticonvulsive property of TPM.
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Affiliation(s)
- Tobias Leniger
- Department of Neurology, University of Essen, Hufelandstr. 55, 45122 Essen, Germany.
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40
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Jeong J, Suh S, Guan C, Tsay YF, Moran N, Oh CJ, An CS, Demchenko KN, Pawlowski K, Lee Y. A nodule-specific dicarboxylate transporter from alder is a member of the peptide transporter family. PLANT PHYSIOLOGY 2004; 134:969-78. [PMID: 15001700 PMCID: PMC389920 DOI: 10.1104/pp.103.032102] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Revised: 10/12/2003] [Accepted: 12/23/2003] [Indexed: 05/17/2023]
Abstract
Alder (Alnus glutinosa) and more than 200 angiosperms that encompass 24 genera are collectively called actinorhizal plants. These plants form a symbiotic relationship with the nitrogen-fixing actinomycete Frankia strain HFPArI3. The plants provide the bacteria with carbon sources in exchange for fixed nitrogen, but this metabolite exchange in actinorhizal nodules has not been well defined. We isolated an alder cDNA from a nodule cDNA library by differential screening with nodule versus root cDNA and found that it encoded a transporter of the PTR (peptide transporter) family, AgDCAT1. AgDCAT1 mRNA was detected only in the nodules and not in other plant organs. Immunolocalization analysis showed that AgDCAT1 protein is localized at the symbiotic interface. The AgDCAT1 substrate was determined by its heterologous expression in two systems. Xenopus laevis oocytes injected with AgDCAT1 cRNA showed an outward current when perfused with malate or succinate, and AgDCAT1 was able to complement a dicarboxylate uptake-deficient Escherichia coli mutant. Using the E. coli system, AgDCAT1 was shown to be a dicarboxylate transporter with a K(m) of 70 microm for malate. It also transported succinate, fumarate, and oxaloacetate. To our knowledge, AgDCAT1 is the first dicarboxylate transporter to be isolated from the nodules of symbiotic plants, and we suggest that it may supply the intracellular bacteria with dicarboxylates as carbon sources.
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Affiliation(s)
- Jeeyon Jeong
- Department of Life Science, Pohang University of Science and Technology, Hyoja-dong, san 31, Pohang 790-784, Korea
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Lelongt B, Ronco P. Role of extracellular matrix in kidney development and repair. Pediatr Nephrol 2003; 18:731-42. [PMID: 12811645 DOI: 10.1007/s00467-003-1153-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2002] [Revised: 02/13/2003] [Accepted: 02/14/2003] [Indexed: 12/11/2022]
Abstract
Extracellular matrix (ECM) molecules and their receptors exert a dynamic role in cell-matrix interactions during kidney development and repair processes. They provide a physical substratum for the spatial organization of the cells, but also regulate cell growth and proliferation by interacting with growth factors. In addition, they can regulate signal transduction pathways by binding to integrins or by modulating the activity of signaling molecules such as Wnts. ECM and ECM-related molecules control multiple (if not all) steps of kidney development, including ureteric bud branching morphogenesis, mesenchymal condensation, nephron formation, terminal differentiation of renal tubules, and glomerular basement membrane assembly. Their role still needs to be better documented in renal repair. The emergence of conditionally mutated mice for basement membrane components will provide a useful tool to demonstrate further the involvement of ECM and ECM-related proteins in development and repair.
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Affiliation(s)
- Brigitte Lelongt
- Institut National de la Santé et de la Recherche Médicale, Unité 489, Hôpital Tenon (AP-HP), 4 rue de la Chine, 75020 Paris, France.
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