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Rodrigues MC, Oliveira LBF, Vieira MAR, Caruso-Neves C, Peruchetti DB. Receptor-mediated endocytosis in kidney cells during physiological and pathological conditions. CURRENT TOPICS IN MEMBRANES 2024; 93:1-25. [PMID: 39181576 DOI: 10.1016/bs.ctm.2024.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Mammalian cell membranes are very dynamic where they respond to several environmental stimuli by rearranging the membrane composition by basic biological processes, including endocytosis. In this context, receptor-mediated endocytosis, either clathrin-dependent or caveolae-dependent, is involved in different physiological and pathological conditions. In the last years, an important amount of evidence has been reported that kidney function involves the modulation of different types of endocytosis, including renal protein handling. In addition, the dysfunction of the endocytic machinery is involved with the development of proteinuria as well as glomerular and tubular injuries observed in kidney diseases associated with hypertension, diabetes, and others. In this present review, we will discuss the mechanisms underlying the receptor-mediated endocytosis in different glomerular cells and proximal tubule epithelial cells as well as their modulation by different factors during physiological and pathological conditions. These findings could help to expand the current understanding regarding renal protein handling as well as identify possible new therapeutic targets to halt the progression of kidney disease.
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Affiliation(s)
- Mariana C Rodrigues
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Laura B F Oliveira
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Maria Aparecida R Vieira
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Celso Caruso-Neves
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil; Rio de Janeiro Innovation Network in Nanosystems for Health-NanoSAUDE/FAPERJ, Rio de Janeiro, RJ, Brazil; Instituto Nacional de Ciência e Tecnologia em Medicina Regenerativa, INCT-Regenera, Conselho Nacional de Desenvolvimento Científico e Tecnológico/MCTI, Rio de Janeiro, RJ, Brazil
| | - Diogo B Peruchetti
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil; Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica, INCT-NANOBiofar, Conselho Nacional de Desenvolvimento Científico e Tecnológico/MCTI, Belo Horizonte, MG, Brazil.
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2
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Wang Y, Xu L, Zhang Y, Fu H, Gao L, Guan Y, Gu W, Sun J, Chen X, Yang F, Lai E, Wang J, Jin Y, Kou Z, Qiu X, Mao J, Hu L. Dent disease 1-linked novel CLCN5 mutations result in aberrant location and reduced ion currents. Int J Biol Macromol 2024; 257:128564. [PMID: 38061527 DOI: 10.1016/j.ijbiomac.2023.128564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 11/12/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023]
Abstract
Dent disease is a rare renal tubular disease with X-linked recessive inheritance characterized by low molecular weight proteinuria (LMWP), hypercalciuria, and nephrocalcinosis. Mutations disrupting the 2Cl-/1H+ exchange activity of chloride voltage-gated channel 5 (CLCN5) have been causally linked to the most common form, Dent disease 1 (DD1), although the pathophysiological mechanisms remain unclear. Here, we conducted the whole exome capture sequencing and bioinformatics analysis within our DD1 cohort to identify two novel causal mutations in CLCN5 (c.749 G > A, p. G250D, c.829 A > C, p. T277P). Molecular dynamics simulations of ClC-5 homology model suggested that these mutations potentially may induce structural changes, destabilizing ClC-5. Overexpression of variants in vitro revealed aberrant subcellular localization in the endoplasmic reticulum (ER), significant accumulation of insoluble aggregates, and disrupted ion transport function in voltage clamp recordings. Moreover, human kidney-2 (HK-2) cells overexpressing either G250D or T277P displayed higher cell-substrate adhesion, migration capability but reduced endocytic function, as well as substantially altered transcriptomic profiles with G250D resulting in stronger deleterious effects. These cumulative findings supported pathogenic role of these ClC-5 mutations in DD1 and suggested a cellular mechanism for disrupted renal function in Dent disease patients, as well as a potential target for diagnostic biomarker or therapeutic strategy development.
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Affiliation(s)
- Yan Wang
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Lizhen Xu
- Department of Biophysics, and Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Ying Zhang
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China
| | - Haidong Fu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Langping Gao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Yuelin Guan
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Weizhong Gu
- Department of Pathology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Jingmiao Sun
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Xiangjun Chen
- Eye Center of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou 310020, China
| | - Fan Yang
- Department of Biophysics, and Kidney Disease Center of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - EnYin Lai
- Department of Physiology School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China
| | - Jingjing Wang
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Yanyan Jin
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Ziqi Kou
- Institute for Brain Research and Rehabilitation, and Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou 510631, China
| | - Xingyu Qiu
- Department of Physiology School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China.
| | - Lidan Hu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China.
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3
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Ran L, Yan T, Zhang Y, Niu Z, Kan Z, Song Z. The recycling regulation of sodium-hydrogen exchanger isoform 3(NHE3) in epithelial cells. Cell Cycle 2021; 20:2565-2582. [PMID: 34822321 DOI: 10.1080/15384101.2021.2005274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
As the main exchanger of electroneutral NaCl absorption, sodium-hydrogen exchanger isoform 3 (NHE3) circulates in the epithelial brush border (BB) and intracellular compartments in a multi-protein complex. The size of the NHE3 complex changes during rapid regulation events. Recycling regulation of NHE3 in epithelial cells can be roughly divided into three stages. First, when stimulated by Ca2+, cGMP, and cAMP-dependent signaling pathways, NHE3 is converted from an immobile complex found at the apical microvilli (MV) into an easily internalized and mobile form that relocates to a compartment near the base of the MV. Second, NHE3 is internalized by clathrin and albumin-dependent pathways into cytoplasmic endosomal compartments, where the complex is reprocessed and reassembled. Finally, NHE3 is translocated from the recycling endosomes (REs) to the apex of epithelial cells, a process that can be stimulated by an increase in sodium-glucose cotransporter 1 (SGLT1) activity, epidermal growth factor receptor (EGFR) signaling, Ca2+ signaling, and binding to βPix and SH3 and multiple ankyrin repeat domains 2 (Shank2) proteins. This review describes the molecular steps and protein interactions involved in the recycling movement of NHE3 from the apex of epithelial cells, into vesicles, where it is reprocessed and reassembled, and returned to its original location on the plasma membrane, where it exerts its physiological function.
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Affiliation(s)
- Ling Ran
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Tao Yan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, China
| | - Yiling Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zheng Niu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zifei Kan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
| | - Zhenhui Song
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Southwest University, Rongchang, China
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4
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Durán M, Burballa C, Cantero-Recasens G, Butnaru CM, Malhotra V, Ariceta G, Sarró E, Meseguer A. Novel Dent disease 1 cellular models reveal biological processes underlying ClC-5 loss-of-function. Hum Mol Genet 2021; 30:1413-1428. [PMID: 33987651 PMCID: PMC8283206 DOI: 10.1093/hmg/ddab131] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/23/2021] [Accepted: 04/26/2021] [Indexed: 01/04/2023] Open
Abstract
Dent disease 1 (DD1) is a rare X-linked renal proximal tubulopathy characterized by low molecular weight proteinuria and variable degree of hypercalciuria, nephrocalcinosis and/or nephrolithiasis, progressing to chronic kidney disease. Although mutations in the electrogenic Cl-/H+ antiporter ClC-5, which impair endocytic uptake in proximal tubule cells, cause the disease, there is poor genotype-phenotype correlation and their contribution to proximal tubule dysfunction remains unclear. To further discover the mechanisms linking ClC-5 loss-of-function to proximal tubule dysfunction, we have generated novel DD1 cellular models depleted of ClC-5 and carrying ClC-5 mutants p.(Val523del), p.(Glu527Asp) and p.(Ile524Lys) using the human proximal tubule-derived RPTEC/TERT1 cell line. Our DD1 cellular models exhibit impaired albumin endocytosis, increased substrate adhesion and decreased collective migration, correlating with a less differentiated epithelial phenotype. Despite sharing functional features, these DD1 cell models exhibit different gene expression profiles, being p.(Val523del) ClC-5 the mutation showing the largest differences. Gene set enrichment analysis pointed to kidney development, anion homeostasis, organic acid transport, extracellular matrix organization and cell-migration biological processes as the most likely involved in DD1 pathophysiology. In conclusion, our results revealed the pathways linking ClC-5 mutations with tubular dysfunction and, importantly, provide new cellular models to further study DD1 pathophysiology.
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Affiliation(s)
- Mónica Durán
- Renal Physiopathology Group, Vall d'Hebron Research Institute (VHIR)-CIBBIM Nanomedicine, Barcelona, Spain
| | - Carla Burballa
- Renal Physiopathology Group, Vall d'Hebron Research Institute (VHIR)-CIBBIM Nanomedicine, Barcelona, Spain
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Gerard Cantero-Recasens
- Renal Physiopathology Group, Vall d'Hebron Research Institute (VHIR)-CIBBIM Nanomedicine, Barcelona, Spain
| | - Cristian M Butnaru
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Vivek Malhotra
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
| | - Gema Ariceta
- Renal Physiopathology Group, Vall d'Hebron Research Institute (VHIR)-CIBBIM Nanomedicine, Barcelona, Spain
- Pediatric Nephrology Department, Vall d'Hebron University Hospital, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Eduard Sarró
- Renal Physiopathology Group, Vall d'Hebron Research Institute (VHIR)-CIBBIM Nanomedicine, Barcelona, Spain
| | - Anna Meseguer
- Renal Physiopathology Group, Vall d'Hebron Research Institute (VHIR)-CIBBIM Nanomedicine, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica de Medicina, Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain
- Red de Investigación Renal (REDINREN), Instituto de Salud Carlos III-FEDER, Madrid, Spain
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Gianesello L, Del Prete D, Ceol M, Priante G, Calò LA, Anglani F. From protein uptake to Dent disease: An overview of the CLCN5 gene. Gene 2020; 747:144662. [PMID: 32289351 DOI: 10.1016/j.gene.2020.144662] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/07/2020] [Indexed: 12/12/2022]
Abstract
Proteinuria is a well-known risk factor, not only for renal disorders, but also for several other problems such as cardiovascular diseases and overall mortality. In the kidney, the chloride channel Cl-/H+ exchanger ClC-5 encoded by the CLCN5 gene is actively involved in preventing protein loss. This action becomes evident in patients suffering from the rare proximal tubulopathy Dent disease because they carry a defective ClC-5 due to CLCN5 mutations. In fact, proteinuria is the distinctive clinical sign of Dent disease, and mainly involves the loss of low-molecular-weight proteins. The identification of CLCN5 disease-causing mutations has greatly improved our understanding of ClC-5 function and of the ClC-5-related physiological processes in the kidney. This review outlines current knowledge regarding the CLCN5 gene and its protein product, providing an update on ClC-5 function in tubular and glomerular cells, and focusing on its relationship with proteinuria and Dent disease.
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Affiliation(s)
- Lisa Gianesello
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Dorella Del Prete
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Monica Ceol
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Giovanna Priante
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Lorenzo Arcangelo Calò
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Franca Anglani
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
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6
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Ye Q, Shen Q, Rao J, Zhang A, Zheng B, Liu X, Shen Y, Chen Z, Wu Y, Hou L, Jian S, Wei M, Ma M, Sun S, Li Q, Dang X, Wang Y, Xu H, Mao J. Multicenter study of the clinical features and mutation gene spectrum of Chinese children with Dent disease. Clin Genet 2020; 97:407-417. [PMID: 31674016 DOI: 10.1111/cge.13663] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 10/07/2019] [Accepted: 10/12/2019] [Indexed: 01/21/2023]
Abstract
Dent disease is a rare X-linked recessive inherited tubular disease. In this multicenter study, the clinical presentation and genetic background of Chinese children with Dent disease are studied to improve the cognition and diagnostic ability of pediatricians. In this prospective cohort, we described the genotype and phenotype of a national cohort composed of 45 pediatric probands with Dent disease belonging to 45 families from 12 different regions of China recruited from 2014 to 2018 by building up the multicenter registration system. The CLCN5 gene from 32 affected families revealed 28 different mutations. The OCRL gene from 13 affected families revealed 13 different mutations. The incidence of low-molecular-weight proteinuria (LMWP) in both Dent disease type 1 populations and Dent disease type 2 populations was 100.0%; however, the incidence of other manifestations was not high, which was similar to previously reported data. Therefore, LMWP is a key clinical feature that should alert clinicians to the possibility of Dent disease. A high amount of LMWP combined with positive gene test results can be used as the diagnostic criteria for this disease. The diagnostic criteria are helpful in reducing the missed diagnosis of this disease and are beneficial for protecting the renal function of these patients through early diagnosis and early intervention.
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Affiliation(s)
- Qing Ye
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National clinical research center for child health, Hangzhou, China
| | - Qian Shen
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China.,Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Shanghai, China.,Shanghai Key Lab of Birth Defect, Children's Hospital of Fudan University, Shanghai, China
| | - Jia Rao
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China.,Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Shanghai, China.,Shanghai Key Lab of Birth Defect, Children's Hospital of Fudan University, Shanghai, China
| | - Aihua Zhang
- Department of Nephrology, Nanjing Children's Hospital Affiliated to Nanjing Medical University, Nanjing, China
| | - Bixia Zheng
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University Nanjing, China
| | - Xiaorong Liu
- Department of Nephrology, Bejing Children's Hospital Affiliated to Capital University of Medical Science, Beijing, China.,Beijing Children's Key Laboratory of Chronic Kidney Disease and Blood Purification, Beijing, China
| | - Ying Shen
- Department of Nephrology, Bejing Children's Hospital Affiliated to Capital University of Medical Science, Beijing, China.,Beijing Children's Key Laboratory of Chronic Kidney Disease and Blood Purification, Beijing, China
| | - Zhi Chen
- Department of Nephrology, Bejing Children's Hospital Affiliated to Capital University of Medical Science, Beijing, China.,Beijing Children's Key Laboratory of Chronic Kidney Disease and Blood Purification, Beijing, China
| | - Yubing Wu
- Department of Pediatric Nephrology and Rheumatology, Shengfing Hospital of China Medical University, Shenyang, China
| | - Ling Hou
- Department of Pediatric Nephrology and Rheumatology, Shengfing Hospital of China Medical University, Shenyang, China
| | - Shan Jian
- Department of Pediatrics, Peking Union Medical College Hospital, Beijing, China
| | - Min Wei
- Department of Pediatrics, Peking Union Medical College Hospital, Beijing, China
| | - Mingsheng Ma
- Department of Pediatrics, Peking Union Medical College Hospital, Beijing, China
| | - Shuzhen Sun
- Department of Pediatric, Nephrology, Rheumatism and Immunology, Shandong Provincial Hospital, Jinan, China
| | - Qian Li
- Department of Pediatric, Nephrology, Rheumatism and Immunology, Shandong Provincial Hospital, Jinan, China
| | - Xiqiang Dang
- Department of Pediatric, Xiangya Hospital Central South University, Changsha, China
| | - Ying Wang
- Department of Pediatric, Xiangya Hospital Central South University, Changsha, China
| | - Hong Xu
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China.,Shanghai Kidney Development and Pediatric Kidney Disease Research Center, Shanghai, China.,Shanghai Key Lab of Birth Defect, Children's Hospital of Fudan University, Shanghai, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National clinical research center for child health, Hangzhou, China
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Anglani F, Gianesello L, Beara-Lasic L, Lieske J. Dent disease: A window into calcium and phosphate transport. J Cell Mol Med 2019; 23:7132-7142. [PMID: 31472005 PMCID: PMC6815805 DOI: 10.1111/jcmm.14590] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/22/2019] [Accepted: 07/24/2019] [Indexed: 12/19/2022] Open
Abstract
This review examines calcium and phosphate transport in the kidney through the lens of the rare X-linked genetic disorder Dent disease. Dent disease type 1 (DD1) is caused by mutations in the CLCN5 gene encoding ClC-5, a Cl- /H+ antiporter localized to early endosomes of the proximal tubule (PT). Phenotypic features commonly include low molecular weight proteinuria (LMWP), hypercalciuria, focal global sclerosis and chronic kidney disease; calcium nephrolithiasis, nephrocalcinosis and hypophosphatemic rickets are less commonly observed. Although it is not surprising that abnormal endosomal function and recycling in the PT could result in LMWP, it is less clear how ClC-5 dysfunction disturbs calcium and phosphate metabolism. It is known that the majority of calcium and phosphate transport occurs in PT cells, and PT endocytosis is essential for calcium and phosphorus reabsorption in this nephron segment. Evidence from ClC-5 KO models suggests that ClC-5 mediates parathormone endocytosis from tubular fluid. In addition, ClC-5 dysfunction alters expression of the sodium/proton exchanger NHE3 on the PT apical surface thus altering transcellular sodium movement and hence paracellular calcium reabsorption. A potential role for NHE3 dysfunction in the DD1 phenotype has never been investigated, either in DD models or in patients with DD1, even though patients with DD1 exhibit renal sodium and potassium wasting, especially when exposed to even a low dose of thiazide diuretic. Thus, insights from the rare disease DD1 may inform possible underlying mechanisms for the phenotype of hypercalciuria and idiopathic calcium stones.
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Affiliation(s)
- Franca Anglani
- Division of Nephrology, Department of Medicine, Laboratory of Histomorphology and Molecular Biology of the Kidney, University of Padua, Padua, Italy
| | - Lisa Gianesello
- Division of Nephrology, Department of Medicine, Laboratory of Histomorphology and Molecular Biology of the Kidney, University of Padua, Padua, Italy
| | - Lada Beara-Lasic
- Division of Nephrology, New York University School of Medicine, New York, NY, USA
| | - John Lieske
- Division of Nephrology and Hypertension, Department of Medicine, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
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8
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Jentsch TJ, Pusch M. CLC Chloride Channels and Transporters: Structure, Function, Physiology, and Disease. Physiol Rev 2018; 98:1493-1590. [DOI: 10.1152/physrev.00047.2017] [Citation(s) in RCA: 214] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
CLC anion transporters are found in all phyla and form a gene family of eight members in mammals. Two CLC proteins, each of which completely contains an ion translocation parthway, assemble to homo- or heteromeric dimers that sometimes require accessory β-subunits for function. CLC proteins come in two flavors: anion channels and anion/proton exchangers. Structures of these two CLC protein classes are surprisingly similar. Extensive structure-function analysis identified residues involved in ion permeation, anion-proton coupling and gating and led to attractive biophysical models. In mammals, ClC-1, -2, -Ka/-Kb are plasma membrane Cl−channels, whereas ClC-3 through ClC-7 are 2Cl−/H+-exchangers in endolysosomal membranes. Biological roles of CLCs were mostly studied in mammals, but also in plants and model organisms like yeast and Caenorhabditis elegans. CLC Cl−channels have roles in the control of electrical excitability, extra- and intracellular ion homeostasis, and transepithelial transport, whereas anion/proton exchangers influence vesicular ion composition and impinge on endocytosis and lysosomal function. The surprisingly diverse roles of CLCs are highlighted by human and mouse disorders elicited by mutations in their genes. These pathologies include neurodegeneration, leukodystrophy, mental retardation, deafness, blindness, myotonia, hyperaldosteronism, renal salt loss, proteinuria, kidney stones, male infertility, and osteopetrosis. In this review, emphasis is laid on biophysical structure-function analysis and on the cell biological and organismal roles of mammalian CLCs and their role in disease.
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Affiliation(s)
- Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Michael Pusch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany; and Istituto di Biofisica, Consiglio Nazionale delle Ricerche, Genova, Italy
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9
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Briffa JF, Grinfeld E, Poronnik P, McAinch AJ, Hryciw DH. Uptake of leptin and albumin via separate pathways in proximal tubule cells. Int J Biochem Cell Biol 2016; 79:194-198. [PMID: 27594412 DOI: 10.1016/j.biocel.2016.08.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 08/15/2016] [Accepted: 08/29/2016] [Indexed: 01/06/2023]
Abstract
The adipokine leptin and oncotic protein albumin are endocytosed in the proximal tubule via the scavenger receptor megalin. Leptin reduces megalin expression and activates cell signalling pathways that upregulate fibrotic protein expression. The aim of this study was to investigate if leptin uptake in proximal tubule cells was via the albumin-megalin endocytic complex. In immortalised proximal tubule Opossum kidney cells (OK) fluorescent leptin and albumin co-localised following 5min exposure, however there was no co-localisation at 10, 20 and 30min exposure. In OK cells, acute exposure to leptin for 2h did not alter NHE3, ClC-5, NHERF1 and NHERF2 mRNA. However, acute leptin exposure increased NHERF2 protein expression in proximal tubule cells. In OK cells, immunoprecipitation experimentation indicated leptin did not bind to ClC-5. Leptin uptake in OK cells was enhanced by bafilomycin and ammonium chloride treatment, demonstrating that uptake was not dependent on lysosomal pH. Thus, it is likely that two pools of megalin exist in proximal tubule cells to facilitate separate uptake of leptin and albumin by endocytosis.
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Affiliation(s)
- Jessica F Briffa
- Centre For Chronic Disease, College of Health and Biomedicine, Victoria University, St. Albans, VIC 3021, Australia; Department of Physiology, The University of Melbourne, Parkville, Melbourne, VIC 3010, Australia
| | - Esther Grinfeld
- Centre For Chronic Disease, College of Health and Biomedicine, Victoria University, St. Albans, VIC 3021, Australia
| | - Philip Poronnik
- School of Medical Sciences, The Bosch Institute, The University of Sydney, NSW 2006, Australia
| | - Andrew J McAinch
- Centre For Chronic Disease, College of Health and Biomedicine, Victoria University, St. Albans, VIC 3021, Australia
| | - Deanne H Hryciw
- Centre For Chronic Disease, College of Health and Biomedicine, Victoria University, St. Albans, VIC 3021, Australia; Department of Physiology, The University of Melbourne, Parkville, Melbourne, VIC 3010, Australia.
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10
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He P, Zhao L, No YR, Karvar S, Yun CC. The NHERF1 PDZ1 domain and IRBIT interact and mediate the activation of Na+/H+ exchanger 3 by ANG II. Am J Physiol Renal Physiol 2016; 311:F343-51. [PMID: 27279487 DOI: 10.1152/ajprenal.00247.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 06/01/2016] [Indexed: 11/22/2022] Open
Abstract
Na(+)/H(+) exchanger (NHE)3, a major Na(+) transporter in the luminal membrane of the proximal tubule, is subject to ANG II regulation in renal Na(+)/fluid absorption and blood pressure control. We have previously shown that inositol 1,4,5-trisphosphate receptor-binding protein released with inositol 1,4,5-trisphosphate (IRBIT) mediates ANG II-induced exocytosis of NHE3 in cultured proximal tubule epithelial cells. In searching for scaffold protein(s) that coordinates with IRBIT in NHE3 trafficking, we found that NHE regulatory factor (NHERF)1, NHE3, and IRBIT proteins were coexpressed in the same macrocomplexes and that loss of ANG II type 1 receptors decreased their expression in the renal brush-border membrane. We found that NHERF1 was required for ANG II-mediated forward trafficking and activation of NHE3 in cultured cells. ANG II induced a concomitant increase of NHERF1 interactions with NHE3 and IRBIT, which were abolished when the NHERF1 PDZ1 domain was removed. Overexpression of a yellow fluorescent protein-NHERF1 construct that lacks PDZ1, but not PDZ2, failed to exaggerate the ANG II-dependent increase of NHE3 expression in the apical membrane. Moreover, exogenous expression of PDZ1 exerted a dominant negative effect on NHE3 activation by ANG II. We further demonstrated that IRBIT was indispensable for the ANG II-provoked increase in NHERF1-NHE3 interactions and that phosphorylation of IRBIT at Ser(68) was necessary for the assembly of the NHEF1-IRBIT-NHE3 complex. Taken together, our findings suggest that NHERF1 mediates ANG II-induced activation of renal NHE3, which requires coordination between IRBIT and the NHERF1 PDZ1 domain in binding and transporting NHE3.
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Affiliation(s)
- Peijian He
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia;
| | - Luqing Zhao
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Department of Gastroenterology, Beijing Hospital of Traditional Chinese Medicine affiliated with Capital Medical University, Beijing, China
| | - Yi Ran No
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Serhan Karvar
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - C Chris Yun
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Atlanta Veterans Affairs Medical Center, Decatur, Georgia; and Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia
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11
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Sun L, Zheng J, Wang Q, Song R, Liu H, Meng R, Tao T, Si Y, Jiang W, He J. NHERF1 regulates actin cytoskeleton organization through modulation of α-actinin-4 stability. FASEB J 2015; 30:578-89. [PMID: 26432781 DOI: 10.1096/fj.15-275586] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 09/21/2015] [Indexed: 01/12/2023]
Abstract
The actin cytoskeleton is composed of a highly dynamic network of filamentous proteins, yet the molecular mechanism that regulates its organization and remodeling remains elusive. In this study, Na(+)/H(+) exchanger regulatory factor (NHERF)-1 loss-of-function and gain-of-function experiments reveal that polymerized actin cytoskeleton (F-actin) in HeLa cells is disorganized by NHERF1, whereas actin protein expression levels exhibit no detectable change. To elucidate the molecular mechanism underlying actin cytoskeleton disorganization by NHERF1, a combined 2-dimensional electrophoresis-matrix-assisted laser desorption/ionization-time of flight mass spectrometry approach was used to screen for proteins regulated by NHERF1 in HeLa cells. α-Actinin-4, an actin cross-linking protein, was identified. Glutathione S-transferase pull-down and coimmunoprecipitation studies showed the α-actinin-4 carboxyl-terminal region specifically interacted with the NHERF1 postsynaptic density 95/disc-large/zona occludens-1 domain. The NHERF1/α-actinin-4 interaction increased α-actinin-4 ubiquitination and decreased its expression levels, resulting in actin cytoskeleton disassembly. Our study identified α-actinin-4 as a novel NHERF1 interaction partner and provided new insights into the regulatory mechanism of the actin cytoskeleton by NHERF1.
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Affiliation(s)
- Licui Sun
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Junfang Zheng
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Qiqi Wang
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Ran Song
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Hua Liu
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Ran Meng
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Tao Tao
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Yang Si
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Wenguo Jiang
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Junqi He
- *Department of Biochemistry and Molecular Biology, Capital Medical University, Beijing, China; Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University-Cardiff University Joint Centre for Biomedical Research, Cancer Institute of Capital Medical University, Beijing, China; and Metastasis and Angiogenesis Research Group, Department of Surgery, Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
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12
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Mansour-Hendili L, Blanchard A, Le Pottier N, Roncelin I, Lourdel S, Treard C, González W, Vergara-Jaque A, Morin G, Colin E, Holder-Espinasse M, Bacchetta J, Baudouin V, Benoit S, Bérard E, Bourdat-Michel G, Bouchireb K, Burtey S, Cailliez M, Cardon G, Cartery C, Champion G, Chauveau D, Cochat P, Dahan K, De la Faille R, Debray FG, Dehoux L, Deschenes G, Desport E, Devuyst O, Dieguez S, Emma F, Fischbach M, Fouque D, Fourcade J, François H, Gilbert-Dussardier B, Hannedouche T, Houillier P, Izzedine H, Janner M, Karras A, Knebelmann B, Lavocat MP, Lemoine S, Leroy V, Loirat C, Macher MA, Martin-Coignard D, Morin D, Niaudet P, Nivet H, Nobili F, Novo R, Faivre L, Rigothier C, Roussey-Kesler G, Salomon R, Schleich A, Sellier-Leclerc AL, Soulami K, Tiple A, Ulinski T, Vanhille P, Van Regemorter N, Jeunemaître X, Vargas-Poussou R. Mutation Update of the CLCN5 Gene Responsible for Dent Disease 1. Hum Mutat 2015; 36:743-52. [PMID: 25907713 DOI: 10.1002/humu.22804] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 04/08/2015] [Indexed: 02/06/2023]
Abstract
Dent disease is a rare X-linked tubulopathy characterized by low molecular weight proteinuria, hypercalciuria, nephrocalcinosis and/or nephrolithiasis, progressive renal failure, and variable manifestations of other proximal tubule dysfunctions. It often progresses over a few decades to chronic renal insufficiency, and therefore molecular characterization is important to allow appropriate genetic counseling. Two genetic subtypes have been described to date: Dent disease 1 is caused by mutations of the CLCN5 gene, coding for the chloride/proton exchanger ClC-5; and Dent disease 2 by mutations of the OCRL gene, coding for the inositol polyphosphate 5-phosphatase OCRL-1. Herein, we review previously reported mutations (n = 192) and their associated phenotype in 377 male patients with Dent disease 1 and describe phenotype and novel (n = 42) and recurrent mutations (n = 24) in a large cohort of 117 Dent disease 1 patients belonging to 90 families. The novel missense and in-frame mutations described were mapped onto a three-dimensional homology model of the ClC-5 protein. This analysis suggests that these mutations affect the dimerization process, helix stability, or transport. The phenotype of our cohort patients supports and extends the phenotype that has been reported in smaller studies.
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Affiliation(s)
- Lamisse Mansour-Hendili
- Faculté de Médecine, Université Paris Descartes, Paris, France.,Assistance Publique-Hôpitaux de Paris, Service de Génétique, Hôpital Européen Georges Pompidou, Paris, France
| | - Anne Blanchard
- Faculté de Médecine, Université Paris Descartes, Paris, France.,INSERM, UMR970, Paris-Cardiovascular Research Center, Paris, France.,Assistance Publique-Hôpitaux de Paris, Centre d'investigation clinique, Hôpital Européen Georges Pompidou, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
| | - Nelly Le Pottier
- Assistance Publique-Hôpitaux de Paris, Service de Génétique, Hôpital Européen Georges Pompidou, Paris, France
| | - Isabelle Roncelin
- Assistance Publique-Hôpitaux de Paris, Service de Génétique, Hôpital Européen Georges Pompidou, Paris, France
| | - Stéphane Lourdel
- Sorbonne Universités, UPMC Université, Paris, France.,INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR S1138, Centre de Recherche des Cordeliers, CNRS ERL 8228, Paris, F-75006, France
| | - Cyrielle Treard
- Assistance Publique-Hôpitaux de Paris, Service de Génétique, Hôpital Européen Georges Pompidou, Paris, France.,INSERM, UMR970, Paris-Cardiovascular Research Center, Paris, France
| | - Wendy González
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca, Chile
| | - Ariela Vergara-Jaque
- Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca, Chile
| | - Gilles Morin
- Service de Génétique et Oncogénétique, Centre Hospitalier Universitaire Amiens Picardie, Amiens, France
| | - Estelle Colin
- Département de Biochimie et Génétique, LUNAM Angers, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Muriel Holder-Espinasse
- Département de Génétique, Centre Hospitalier Universitaire de Lille, Lille, France.,Department of Clinical Genetics, Guy's Hospital, London, United Kingdom
| | - Justine Bacchetta
- Centre de Référence des Maladies Rénales Rares. Service de Néphrologie Rhumatologie Dermatologie Pédiatriques, Hospices Civils de Lyon, Lyon, France
| | - Véronique Baudouin
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Service de Néphrologie, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Stéphane Benoit
- Service de Néphrologie, Centre Hospitalier Universitaire de Tours, Tours, France
| | - Etienne Bérard
- Service de Néphrologie pédiatrique, Centre Hospitalier Universitaire de Nice, Nice, France
| | | | - Karim Bouchireb
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Assistance Publique Hôpitaux de Paris, Hôpital Necker-Enfants-malades, Service de Néphrologie Pédiatrique, Paris, France
| | - Stéphane Burtey
- VRCM, centre de néphrologie et transplantation rénale, Aix-Marseille Université, Marseille, France
| | - Mathilde Cailliez
- Assistance Publique Hôpitaux de Marseille, Unité de Néphrologie Pédiatrique, Hôpital La Timone, Marseille, France
| | - Gérard Cardon
- Service de Néphrologie, Centre Hospitalier de Douai, Douai, France
| | - Claire Cartery
- Assistance Publique-Hôpitaux de Paris, Service de Néphrologie et dialyse, Hôpital Tenon, Paris, France
| | - Gerard Champion
- Département de Pédiatrie, LUNAM Angers, Centre Hospitalier Universitaire d'Angers, Angers, France
| | - Dominique Chauveau
- Centre Hospitalier Universitaire de Toulouse, Département de Néphrologie et Transplantation d'organes, Hôpital Rangueil, Toulouse, France
| | - Pierre Cochat
- Centre de Référence des Maladies Rénales Rares. Service de Néphrologie Rhumatologie Dermatologie Pédiatriques, Hospices Civils de Lyon, Lyon, France
| | - Karin Dahan
- Département de Génétique Humaine, Institut de Pathologie et de Génétique, Gosselies, Belgium
| | - Renaud De la Faille
- Service de Néphrologie Transplantation Dialyse, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
| | | | - Laurenne Dehoux
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Service de Néphrologie, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Georges Deschenes
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Service de Néphrologie, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Estelle Desport
- Service de Néphrologie, Centre Hospitalier Universitaire de Poitiers, Poitiers, France
| | - Olivier Devuyst
- Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium.,Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Stella Dieguez
- Nefrologia Infantil, Hospital General de Agudos Dr. Teodoro Álvarez, Buenos Aires, Argentina
| | - Francesco Emma
- Division of Nephrology and Dialysis, Bambino Gesù Children's Hospital - IRCCS, Rome, Italy
| | - Michel Fischbach
- Service de Pédiatrie, Centre Hospitalier Universitaire Hautepierre, Strasbourg, France
| | - Denis Fouque
- Departement de Néphrology, Centre Hospitalier Universitaire Lyon Sud, Lyon, France
| | - Jacques Fourcade
- Service de Néphrology, Centre Hospitalier de Chambery, Chambery, France
| | - Hélène François
- Assistance Publique-Hôpitaux de Paris, Hôpital Kremlin Bicêtre, Service de Néphrologie, Le Kremlin-Bicêtre, France
| | - Brigitte Gilbert-Dussardier
- Centre Hospitalier Universitaire de Poitiers, Service de Génétique, EA 3808, Université de Poitiers, Poitiers, France
| | - Thierry Hannedouche
- Hôpitaux Universitaires de Strasbourg, Service de Néphrologie et Faculté de Médecine, Université de Strasbourg, Strasbourg, France
| | - Pascal Houillier
- Faculté de Médecine, Université Paris Descartes, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,INSERM, Université Paris Descartes, Sorbonne Paris Cité, UMR S1138, Centre de Recherche des Cordeliers, CNRS ERL 8228, Paris, F-75006, France.,Assistance Publique Hôpitaux de Paris, Département de Physiologie, Hôpital Européen Georges Pompidou, Paris, France
| | - Hassan Izzedine
- Assistance Publique-Hôpitaux de Paris, Hôpital Pitié Salpêtrière, Service de Néphrologie, Paris, France
| | - Marco Janner
- Department of Paediatric Endocrinology, Diabetology and Metabolism, University of Berne Children's Hospital, Berne, Switzerland
| | - Alexandre Karras
- Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Néphrologie, Paris, France
| | - Bertrand Knebelmann
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Assistance Publique Hôpitaux de Paris, Hôpital Necker-Enfants-malades, Service de Néphrologie adulte, Paris, France
| | - Marie-Pierre Lavocat
- Département de Pédiatrie, Centre Hospitalier Universitaire de Saint Etienne, Hôpital Nord, Saint Etienne, France
| | - Sandrine Lemoine
- Hospices Civils de Lyon, Service d'Exploration Fonctionnelle Rénale, Hôpital Edouard-Herriot, Lyon, France
| | - Valérie Leroy
- Hôpital Jeanne de Flandre, Service de Néphrologie Pédiatrique, Centre Hospitalier Universitaire de Lille, Lille, France
| | - Chantal Loirat
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Service de Néphrologie, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Marie-Alice Macher
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Service de Néphrologie, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | | | - Denis Morin
- Unité de Néphrologie Pédiatrique, Centre Hospitalier Universitaire de Montpellier, Montpellier, France
| | - Patrick Niaudet
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Assistance Publique Hôpitaux de Paris, Hôpital Necker-Enfants-malades, Service de Néphrologie Pédiatrique, Paris, France
| | - Hubert Nivet
- Service de Néphrologie, Centre Hospitalier Universitaire de Tours, Tours, France
| | - François Nobili
- Unité de Néphrologie Pédiatrie, Besançon, Centre Hospitalier Universitaire de Besançon, Besançon, France
| | - Robert Novo
- Hôpital Jeanne de Flandre, Service de Néphrologie Pédiatrique, Centre Hospitalier Universitaire de Lille, Lille, France
| | - Laurence Faivre
- Centre de Génétique, Centre Hospitalier Universitaire de Dijon, Dijon, France
| | - Claire Rigothier
- Service de Néphrologie Transplantation Dialyse, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
| | | | - Remi Salomon
- Faculté de Médecine, Université Paris Descartes, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Assistance Publique Hôpitaux de Paris, Hôpital Necker-Enfants-malades, Service de Néphrologie Pédiatrique, Paris, France
| | - Andreas Schleich
- Institute of Nephrology Statspital Waid Zuerich, Zuerich, Switzerland
| | - Anne-Laure Sellier-Leclerc
- Centre de Référence des Maladies Rénales Rares. Service de Néphrologie Rhumatologie Dermatologie Pédiatriques, Hospices Civils de Lyon, Lyon, France
| | | | - Aurélien Tiple
- Centre Hospitalier Universitaire Gabriel-Montpied Service de Néphrologie, Clermont-Ferrand, France
| | - Tim Ulinski
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Assistance Publique-Hôpitaux de Paris, Service de Néphrologie et Transplantation Rénale, Hôpital Trousseau, Paris, France
| | - Philippe Vanhille
- Centre Hospitalier de Valenciennes, Service de Néphrologie et Médecine Interne, Valenciennes, France
| | - Nicole Van Regemorter
- Université Libre de Bruxelles, Hôpital Erasme Département de Génétique Médicale, Brussels, Belgium
| | - Xavier Jeunemaître
- Faculté de Médecine, Université Paris Descartes, Paris, France.,Assistance Publique-Hôpitaux de Paris, Service de Génétique, Hôpital Européen Georges Pompidou, Paris, France.,INSERM, UMR970, Paris-Cardiovascular Research Center, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
| | - Rosa Vargas-Poussou
- Assistance Publique-Hôpitaux de Paris, Service de Génétique, Hôpital Européen Georges Pompidou, Paris, France.,INSERM, UMR970, Paris-Cardiovascular Research Center, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France
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13
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Lee A, Slattery C, Nikolic-Paterson DJ, Hryciw DH, Wilk S, Wilk E, Zhang Y, Valova VA, Robinson PJ, Kelly DJ, Poronnik P. Chloride channel ClC-5 binds to aspartyl aminopeptidase to regulate renal albumin endocytosis. Am J Physiol Renal Physiol 2015; 308:F784-92. [DOI: 10.1152/ajprenal.00322.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 01/04/2015] [Indexed: 12/17/2022] Open
Abstract
ClC-5 is a chloride/proton exchanger that plays an obligate role in albumin uptake by the renal proximal tubule. ClC-5 forms an endocytic complex with the albumin receptor megalin/cubilin. We have identified a novel ClC-5 binding partner, cytosolic aspartyl aminopeptidase (DNPEP; EC 3.4.11.21), that catalyzes the release of N-terminal aspartate/glutamate residues. The physiological role of DNPEP remains largely unresolved. Mass spectrometric analysis of proteins binding to the glutathione- S-transferase (GST)-ClC-5 C terminus identified DNPEP as an interacting partner. Coimmunoprecipitation confirmed that DNPEP and ClC-5 also associated in cells. Further experiments using purified GST-ClC-5 and His-DNPEP proteins demonstrated that the two proteins bound directly to each other. In opossum kidney (OK) cells, confocal immunofluorescence studies revealed that DNPEP colocalized with albumin-containing endocytic vesicles. Overexpression of wild-type DNPEP increased cell-surface levels of ClC-5 and albumin uptake. Analysis of DNPEP-immunoprecipitated products from rat kidney lysate identified β-actin and tubulin, suggesting a role for DNPEP in cytoskeletal maintenance. A DNase I inhibition assay showed a significant decrease in the amount of G actin when DNPEP was overexpressed in OK cells, suggesting a role for DNPEP in stabilizing the cytoskeleton. DNPEP was not present in the urine of healthy rats; however, it was readily detected in the urine in rat models of mild and heavy proteinuria (diabetic nephropathy and anti-glomerular basement membrane disease, respectively). Urinary levels of DNPEP were found to correlate with the severity of proteinuria. Therefore, we have identified another key molecular component of the albumin endocytic machinery in the renal proximal tubule and describe a new role for DNPEP in stabilizing the actin cytoskeleton.
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Affiliation(s)
- Aven Lee
- UQ Centre for Clinical Research, The University of Queensland, Herston, Brisbane, Queensland, Australia
| | - Craig Slattery
- School of Biomolecular and Biomedical Sciences, University College Dublin, Belfield, Dublin, Republic. of Ireland
| | - David J. Nikolic-Paterson
- Department of Nephrology, Monash University Department of Medicine, Monash Medical Centre, Clayton, Victoria, Australia
| | - Deanne H. Hryciw
- Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Sherwin Wilk
- Department of Pharmacology, Mount Sinai School of Medicine, New York, New York
| | - Elizabeth Wilk
- Department of Pharmacology, Mount Sinai School of Medicine, New York, New York
| | - Yuan Zhang
- Department of Medicine, Saint Vincent's Hospital, Fitzroy, Victoria, Australia
| | - Valentina A. Valova
- Children's Medical Research Institute, The University of Sydney, Westmead New South Wales, Australia; and
| | - Phillip J. Robinson
- Children's Medical Research Institute, The University of Sydney, Westmead New South Wales, Australia; and
| | - Darren J. Kelly
- Department of Medicine, Saint Vincent's Hospital, Fitzroy, Victoria, Australia
| | - Philip Poronnik
- School of Medical Sciences and the Bosch Institute, The University of Sydney, New South Wales, Australia
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14
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Briffa JF, Grinfeld E, Mathai ML, Poronnik P, McAinch AJ, Hryciw DH. Acute leptin exposure reduces megalin expression and upregulates TGFβ1 in cultured renal proximal tubule cells. Mol Cell Endocrinol 2015; 401:25-34. [PMID: 25478926 DOI: 10.1016/j.mce.2014.11.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 11/26/2014] [Accepted: 11/28/2014] [Indexed: 01/14/2023]
Abstract
Increased leptin concentrations observed in obesity can lead to proteinuria, suggesting that leptin may play a role in obesity-related kidney disease. Obesity reduces activation of AMP-activated protein kinase (AMPK) and increases transforming growth factor-β1 (TGF-β1) expression in the kidney, leading to albuminuria. Thus we investigated if elevated leptin altered AMPK and TGF-β1 signaling in proximal tubule cells (PTCs). In opossum kidney (OK) PTCs Western blot analysis demonstrated that leptin upregulates TGF-β1 secretion (0.50 µg/ml) and phosphorylated AMPKα (at 0.25, and 0.50 µg/ml), and downregulates megalin expression at all concentrations (0.05-0.50 µg/ml). Using the AMPK inhibitor, Compound C, leptin exposure regulated TGF-β1 expression and secretion in PTCs via an AMPK mediated pathway. In addition, elevated leptin exposure (0.50 µg/ml) reduced albumin handling in OK cells independently of megalin expression. This study demonstrates that leptin upregulates TGF-β1, reduces megalin, and reduces albumin handling in PTCs by an AMPK mediated pathway.
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Affiliation(s)
- Jessica F Briffa
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Vic. 3021, Australia; Department of Physiology, The University of Melbourne, Parkville, Vic. 3010, Australia
| | - Esther Grinfeld
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Vic. 3021, Australia
| | - Michael L Mathai
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Vic. 3021, Australia
| | - Phillip Poronnik
- School of Medical Sciences, The Bosch Institute, The University of Sydney, NSW 2006, Australia
| | - Andrew J McAinch
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Vic. 3021, Australia
| | - Deanne H Hryciw
- Centre for Chronic Disease Prevention and Management, College of Health and Biomedicine, Victoria University, St Albans, Vic. 3021, Australia; Department of Physiology, The University of Melbourne, Parkville, Vic. 3010, Australia.
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15
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Briffa JF, Grinfeld E, McAinch AJ, Poronnik P, Hryciw DH. Short term exposure to elevated levels of leptin reduces proximal tubule cell metabolic activity. Mol Cell Endocrinol 2014; 382:38-45. [PMID: 24036423 DOI: 10.1016/j.mce.2013.09.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 08/08/2013] [Accepted: 09/03/2013] [Indexed: 11/29/2022]
Abstract
Leptin plays a pathophysiological role in the kidney, however, its acute effects on the proximal tubule cells (PTCs) are unknown. In opossum kidney (OK) cells in vitro, Western blot analysis identified that exposure to leptin increases the phosphorylation of the mitogen-activated protein kinase (MAPK) p44/42 and the mammalian target of rapamycin (mTOR). Importantly leptin (0.05, 0.10, 0.25 and 0.50 μg/ml) significantly reduced the metabolic activity of PTCs, and significantly decreased protein content per cell. Investigation of the role of p44/42 and mTOR on metabolic activity and protein content per cell, demonstrated that in the presence of MAPK inhibitor U0126 and mTOR inhibitor Ku-63794, that the mTOR pathway is responsible for the reduction in PTC metabolic activity in response to leptin. However, p44/42 and mTOR play no role the reduced protein content per cell in OKs exposed to leptin. Therefore, leptin modulates metabolic activity in PTCs via an mTOR regulated pathway.
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Affiliation(s)
- Jessica F Briffa
- Biomedical and Lifestyle Diseases (BioLED) Unit, College of Health and Biomedicine, Victoria University, St Albans, VIC 3021, Australia; Department of Physiology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Esther Grinfeld
- Biomedical and Lifestyle Diseases (BioLED) Unit, College of Health and Biomedicine, Victoria University, St Albans, VIC 3021, Australia
| | - Andrew J McAinch
- Biomedical and Lifestyle Diseases (BioLED) Unit, College of Health and Biomedicine, Victoria University, St Albans, VIC 3021, Australia
| | - Philip Poronnik
- School of Medical Sciences, The Bosch Institute, The University of Sydney, NSW 2006, Australia
| | - Deanne H Hryciw
- Biomedical and Lifestyle Diseases (BioLED) Unit, College of Health and Biomedicine, Victoria University, St Albans, VIC 3021, Australia; Department of Physiology, The University of Melbourne, Parkville, VIC 3010, Australia.
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16
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Stauber T, Weinert S, Jentsch TJ. Cell biology and physiology of CLC chloride channels and transporters. Compr Physiol 2013; 2:1701-44. [PMID: 23723021 DOI: 10.1002/cphy.c110038] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Proteins of the CLC gene family assemble to homo- or sometimes heterodimers and either function as Cl(-) channels or as Cl(-)/H(+)-exchangers. CLC proteins are present in all phyla. Detailed structural information is available from crystal structures of bacterial and algal CLCs. Mammals express nine CLC genes, four of which encode Cl(-) channels and five 2Cl(-)/H(+)-exchangers. Two accessory β-subunits are known: (1) barttin and (2) Ostm1. ClC-Ka and ClC-Kb Cl(-) channels need barttin, whereas Ostm1 is required for the function of the lysosomal ClC-7 2Cl(-)/H(+)-exchanger. ClC-1, -2, -Ka and -Kb Cl(-) channels reside in the plasma membrane and function in the control of electrical excitability of muscles or neurons, in extra- and intracellular ion homeostasis, and in transepithelial transport. The mainly endosomal/lysosomal Cl(-)/H(+)-exchangers ClC-3 to ClC-7 may facilitate vesicular acidification by shunting currents of proton pumps and increase vesicular Cl(-) concentration. ClC-3 is also present on synaptic vesicles, whereas ClC-4 and -5 can reach the plasma membrane to some extent. ClC-7/Ostm1 is coinserted with the vesicular H(+)-ATPase into the acid-secreting ruffled border membrane of osteoclasts. Mice or humans lacking ClC-7 or Ostm1 display osteopetrosis and lysosomal storage disease. Disruption of the endosomal ClC-5 Cl(-)/H(+)-exchanger leads to proteinuria and Dent's disease. Mouse models in which ClC-5 or ClC-7 is converted to uncoupled Cl(-) conductors suggest an important role of vesicular Cl(-) accumulation in these pathologies. The important functions of CLC Cl(-) channels were also revealed by human diseases and mouse models, with phenotypes including myotonia, renal loss of salt and water, deafness, blindness, leukodystrophy, and male infertility.
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Affiliation(s)
- Tobias Stauber
- Leibniz-Institut für Molekulare Pharmakologie FMP and Max-Delbrück-Centrum für Molekulare Medizin MDC, Berlin, Germany
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17
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Hu Z, Hu J, Zhang Z, Shen WJ, Yun CC, Berlot CH, Kraemer FB, Azhar S. Regulation of expression and function of scavenger receptor class B, type I (SR-BI) by Na+/H+ exchanger regulatory factors (NHERFs). J Biol Chem 2013; 288:11416-35. [PMID: 23482569 DOI: 10.1074/jbc.m112.437368] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Scavenger receptor class B, type I (SR-BI) binds HDL and mediates selective delivery of cholesteryl esters (CEs) to the liver, adrenals, and gonads for product formation (bile acids and steroids). Because relatively little is known about SR-BI posttranslational regulation in steroidogenic cells, we examined the roles of Na(+)/H(+) exchanger regulatory factors (NHERFs) in regulating SR-BI expression, SR-BI-mediated selective CE uptake, and steroidogenesis. NHERF1 and NHERF2 mRNA and protein are expressed at varying levels in model steroidogenic cell lines and the adrenal, with only low expression of PDZK1 (NHERF3) and NHERF4. Dibutyryl cyclic AMP decreased NHERF1 and NHERF2 and increased SR-BI mRNA expression in primary rat granulosa cells and MLTC-1 cells, whereas ACTH had no effect on NHERF1 and NHERF2 mRNA levels but decreased their protein levels in rat adrenals. Co-immunoprecipitation, colocalization, bimolecular fluorescence complementation, and mutational analysis indicated that SR-BI associates with NHERF1 and NHERF2. NHERF1 and NHERF2 down-regulated SR-BI protein expression through inhibition of its de novo synthesis. NHERF1 and NHERF2 also inhibited SR-BI-mediated selective CE transport and steroidogenesis, which were markedly attenuated by partial deletions of the PDZ1 or PDZ2 domain of NHERF1, the PDZ2 domain of NHERF2, or the MERM domains of NHERF1/2 or by gene silencing of NHERF1/2. Moreover, an intact COOH-terminal PDZ recognition motif (EAKL) in SR-BI is needed. Transient transfection of hepatic cell lines with NHERF1 or NHERF2 caused a significant reduction in endogenous protein levels of SR-BI. Collectively, these data establish NHERF1 and NHERF2 as SR-BI protein binding partners that play a negative role in the regulation of SR-BI expression, selective CE transport, and steroidogenesis.
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Affiliation(s)
- Zhigang Hu
- Geriatric Research, Education and Clinical Center, Veterans Affairs Palo Alto Health Care System, Palo Alto, California 94304, USA
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18
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Jenkin KA, Verty AN, McAinch AJ, Hryciw DH. Endocannabinoids and the renal proximal tubule: An emerging role in diabetic nephropathy. Int J Biochem Cell Biol 2012; 44:2028-31. [DOI: 10.1016/j.biocel.2012.07.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 06/21/2012] [Accepted: 07/09/2012] [Indexed: 01/02/2023]
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19
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Hryciw DH, Jenkin KA, Simcocks AC, Grinfeld E, McAinch AJ, Poronnik P. The interaction between megalin and ClC-5 is scaffolded by the Na⁺-H⁺ exchanger regulatory factor 2 (NHERF2) in proximal tubule cells. Int J Biochem Cell Biol 2012; 44:815-23. [PMID: 22349218 DOI: 10.1016/j.biocel.2012.02.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/22/2012] [Accepted: 02/05/2012] [Indexed: 11/25/2022]
Abstract
Albumin endocytosis in the proximal tubule is mediated by a number of proteins, including the scavenger receptor megalin/cubilin and the PSD-95/Dlg/ZO-1 (PDZ) scaffolds NHERF1 and NHERF2. In addition, in a number of in vitro and in vivo models, the loss of ClC-5 results in a decreased cell surface expression and whole cell level of megalin, suggesting an interaction between these two proteins in vivo. We investigated if ClC-5 and megalin interact directly, and as ClC-5 binds to NHERF2, we investigated if this PDZ scaffold was required for a megalin/ClC-5 complex. GST-pulldown and immunoprecipitation experiments using rat kidney lysate demonstrated an interaction between ClC-5 and megalin, which was mediated by their C-termini. As this interaction may be controlled by a scaffold protein, we characterised any interaction between megalin and NHERF2. Immunoprecipitation experiments indicated that megalin interacts with NHERF2 in vivo, and that this interaction was via an internal NHERF binding domain in the C-terminus of megalin and PDZ2 and the C-terminus of NHERF2. Silencing NHERF2 had no effect on megalin protein levels in the whole cell or plasma membrane. Using siRNA against NHERF2, we demonstrated that NHERF2 was required to facilitate the interaction between megalin and ClC-5. Using fusion proteins, we characterised a protein complex containing ClC-5 and megalin, which is scaffolded by NHERF2, in the absence of any other proteins. Importantly, these observations are the first to describe an interaction between megalin and ClC-5, which is scaffolded by NHERF2 in proximal tubule cells.
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Affiliation(s)
- D H Hryciw
- Biomedical and Lifestyle Diseases Unit, School of Biomedical and Health Sciences, Victoria University, St Albans, VIC 3021, Australia.
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20
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Billing AM, Revets D, Hoffmann C, Turner JD, Vernocchi S, Muller CP. Proteomic profiling of rapid non-genomic and concomitant genomic effects of acute restraint stress on rat thymocytes. J Proteomics 2012; 75:2064-79. [PMID: 22270012 DOI: 10.1016/j.jprot.2012.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Revised: 12/16/2011] [Accepted: 01/07/2012] [Indexed: 02/06/2023]
Abstract
In order to investigate rapid non-genomic effects of acute stress, rats were restrained for 15 min which was sufficient to activate the hypothalamus-pituitary-adrenal (HPA) axis but too short to induce massive genomic effects of cortisol. Subcellular fractions of thymocytes (cytosol, nucleus, membrane) were investigated using quantitative 2D DIGE with MALDI-TOF/TOF mass spectrometry. In total, 108 proteins with differential subcellular localizations were identified. The specificity of the changes induced by psychological stress was reflected by the prominent modulation of proteins involved in the HPA and sympathoadrenal medullar (SAM) axis such as HMGB1 and NHERF1. Intracellular trafficking was characterized by a dominant protein exodus from the cytosol. Real translocation was observed for 9 proteins with 6 that shuttled from the cytosol to the nucleus (HYOU1, HNRPF, HNRPC, STRAP, PSA1, PPA1) and 3 from the nucleus to the cytosol (HMGB1, NHERF1, PSMA1). Proteins showing subcellular reshuffling were largely involved in transcription and translation processes (39 of 108) with a significant enrichment of RNA splicing factors. Bioinformatics analysis revealed significant enrichment for protein kinase A and 14-3-3 signaling, probably reflecting real non-genomic effects. This is the first study investigating rapid effects of stress-induced HPA activation in vivo at the proteome level.
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Affiliation(s)
- Anja M Billing
- Institute of Immunology, Centre de Recherche Public de la Santé/National Public Health Laboratory, 20A, rue Auguste Lumière, L-1950 Luxembourg, Luxembourg
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21
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Hryciw DH, Kruger WA, Briffa JF, Slattery C, Bolithon A, Lee A, Poronnik P. Sgk-1 is a Positive Regulator of Constitutive Albumin Uptake in Renal Proximal Tubule Cells. Cell Physiol Biochem 2012; 30:1215-26. [DOI: 10.1159/000343313] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/28/2012] [Indexed: 12/12/2022] Open
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22
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ClC-5 mutations associated with Dent's disease: a major role of the dimer interface. Pflugers Arch 2011; 463:247-56. [PMID: 22083641 DOI: 10.1007/s00424-011-1052-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 10/23/2011] [Accepted: 10/24/2011] [Indexed: 12/30/2022]
Abstract
Dent's disease is an X-linked recessive disorder affecting the proximal tubules. Mutations in the 2Cl(-)/H(+) exchanger ClC-5 gene CLCN5 are frequently associated with Dent's disease. Functional characterization of mutations of CLCN5 have helped to elucidate the physiopathology of Dent's disease and provided evidence that several different mechanisms underlie the ClC-5 dysfunction in Dent's disease. Modeling studies indicate that many CLCN5 mutations are located at the interface between the monomers of ClC-5, demonstrating that this protein region plays an important role in Dent's disease. On the basis of functional data, CLCN5 mutations can be divided into three different classes. Class 1 mutations impair processing and folding, and as a result, the ClC-5 mutants are retained within the endoplasmic reticulum and targeted for degradation by quality control mechanisms. Class 2 mutations induce a delay in protein processing and reduce the stability of ClC-5. As a consequence, the cell surface expression and currents of the ClC-5 mutants are lower. Class 3 mutations do not alter the trafficking of ClC-5 to the cell surface and early endosomes but induce altered electrical activity. Here, we discuss the functional consequences of the three classes of CLCN5 mutations on ClC-5 structure and function.
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23
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Lin Z, Jin S, Duan X, Wang T, Martini S, Hulamm P, Cha B, Hubbard A, Donowitz M, Guggino SE. Chloride channel (Clc)-5 is necessary for exocytic trafficking of Na+/H+ exchanger 3 (NHE3). J Biol Chem 2011; 286:22833-45. [PMID: 21561868 DOI: 10.1074/jbc.m111.224998] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ClC-5, a chloride/proton exchanger, is predominantly expressed and localized in subapical endosomes of the renal proximal tubule. Mutations of the CLCN5 gene cause Dent disease. The symptoms of Dent disease are replicated in Clcn5 knock-out mice. Absence of ClC-5 in mice is associated with reduced surface expression of NHE3 in proximal tubules. The molecular basis for this change is not fully understood. In this study, we investigated the mechanisms by which ClC-5 regulates trafficking of NHE3. Whether ClC-5-dependent endocytosis, exocytosis, or both contributed to the altered distribution of NHE3 was examined. First, NHE3 activity in proximal tubules of wild type (WT) and Clcn5 KO mice was determined by two-photon microscopy. Basal and dexamethasone-stimulated NHE3 activity of Clcn5 KO mice was decreased compared with that seen in WT mice, whereas the degree of inhibition of NHE3 activity by increasing cellular concentration of cAMP (forskolin) or Ca(2+) (A23187) was not different in WT and Clcn5 KO mice. Second, NHE3-dependent absorption of HCO(3)(-), measured by single tubule perfusion, was reduced in proximal tubules of Clcn5 KO mice. Third, by cell surface biotinylation, trafficking of NHE3 was examined in short hairpin RNA (shRNA) plasmid-transfected opossum kidney cells. Surface NHE3 was reduced in opossum kidney cells with reduced expression of ClC-5, whereas the total protein level of NHE3 did not change. Parathyroid hormone decreased NHE3 surface expression, but the extent of decrease and the rate of endocytosis observed in both scrambled and ClC-5 knockdown cells were not significantly different. However, the rates of basal and dexamethasone-stimulated exocytosis of NHE3 were attenuated in ClC-5 knockdown cells. These results show that ClC-5 plays an essential role in exocytosis of NHE3.
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Affiliation(s)
- Zhihong Lin
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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24
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Claverie-Martín F, Ramos-Trujillo E, García-Nieto V. Dent's disease: clinical features and molecular basis. Pediatr Nephrol 2011; 26:693-704. [PMID: 20936522 DOI: 10.1007/s00467-010-1657-0] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 08/27/2010] [Accepted: 09/06/2010] [Indexed: 02/08/2023]
Abstract
Dent's disease is an X-linked recessive renal tubulopathy characterized by low-molecular-weight proteinuria (LMWP), hypercalciuria, nephrocalcinosis, nephrolithiasis, and progressive renal failure. LMWP is the most constant feature, while the other clinical manifestations show wide variability. Patients also present variable manifestations of proximal tubule dysfunctions, such as aminoaciduria, glucosuria, hyperphosphaturia, kaliuresis, and uricosuria, consistent with renal Fanconi syndrome. Dent's disease affects mainly male children, and female carriers are generally asymptomatic. In two-thirds of patients, the disease is caused by mutations in the CLCN5 gene, which encodes the electrogenic chloride/proton exchanger ClC-5. A few patients have mutations in OCRL1, the gene associated with the oculocerebrorenal syndrome of Lowe, which encodes a phosphatidylinositol-4,5-biphosphate-5-phosphatase (OCRL1). Both ClC-5 and OCRL1 are involved in the endocytic pathway for reabsorption of LMW proteins in the proximal tubule. This review will provide an overview of the important phenotypic characteristics of Dent's disease and summarize the molecular data that have significantly increased our comprehension of the mechanisms causing this disease.
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Affiliation(s)
- Félix Claverie-Martín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
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25
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Donowitz M, Singh S, Singh P, Chakraborty M, Chen Y, Murtazina R, Gucek M, Cole RN, Zachos NC, Salahuddin FF, Kovbasnjuk O, Broere N, Smalley-Freed WG, Reynolds AB, Hubbard AL, Seidler U, Weinman E, de Jonge HR, Hogema BM, Li X. Alterations in the proteome of the NHERF2 knockout mouse jejunal brush border membrane vesicles. Physiol Genomics 2011; 43:674-84. [PMID: 21427361 DOI: 10.1152/physiolgenomics.00258.2010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To identify additional potential functions for the multi-PDZ domain containing protein Na+/H+ exchanger regulatory factor 2 (NHERF2), which is present in the apical domain of intestinal epithelial cells, proteomic studies of mouse jejunal villus epithelial cell brush border membrane vesicles compared wild-type to homozygous NHERF2 knockout FVB mice by a two-dimensional liquid chromatography-tandem mass spectrometry (LC-MS/MS)-iTRAQ approach. Jejunal architecture appeared normal in NHERF2 null in terms of villus length and crypt depth, Paneth cell number, and microvillus structure by electron microscopy. There was also no change in proliferative activity based on BrdU labeling. Four brush border membrane vesicles (BBMV) preparations from wild-type mouse jejunum were compared with four preparations from NHERF2 knockout mice. LC-MS/MS identified 450 proteins in both matched wild-type and NHERF2 null BBMV; 13 proteins were changed in two or more separate BBMV preparations (9 increased and 4 decreased in NHERF2 null mice), while an additional 92 proteins were changed in a single BBMV preparation (68 increased and 24 decreased in NHERF2 null mice). These proteins were categorized as 1) transport proteins (one increased and two decreased in NHERF2 null); 2) signaling molecules (2 increased in NHERF2 null); 3) cytoskeleton/junctional proteins (4 upregulated and 1 downregulated in NHERF2 null); and 4) metabolic proteins/intrinsic BB proteins) (2 upregulated and 1 downregulated in NHERF2 null). Immunoblotting of BBMV was used to validate or extend the findings, demonstrating increase in BBMV of NHERF2 null of MCT1, coronin 3, and ezrin. The proteome of the NHERF2 null mouse small intestinal BB demonstrates up- and downregulation of multiple transport proteins, signaling molecules, cytoskeletal proteins, tight junctional and adherens junction proteins, and proteins involved in metabolism, suggesting involvement of NHERF2 in multiple apical regulatory processes and interactions with luminal contents.
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Affiliation(s)
- M Donowitz
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2195, USA.
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26
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Grand T, L'Hoste S, Mordasini D, Defontaine N, Keck M, Pennaforte T, Genete M, Laghmani K, Teulon J, Lourdel S. Heterogeneity in the processing of
CLCN5
mutants related to Dent disease. Hum Mutat 2011; 32:476-83. [PMID: 21305656 DOI: 10.1002/humu.21467] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Teddy Grand
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
| | - Sébastien L'Hoste
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
| | - David Mordasini
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
| | - Nadia Defontaine
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
| | - Mathilde Keck
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
| | - Thomas Pennaforte
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
| | - Mathieu Genete
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
| | - Kamel Laghmani
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
| | - Jacques Teulon
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
| | - Stéphane Lourdel
- UPMC Univ Paris 06, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- INSERM, UMR_S 872, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
- CNRS, ERL 7226, Laboratoire de génomique, physiologie et physiopathologie rénales, Paris, France
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27
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Jenkin KA, McAinch AJ, Grinfeld E, Hryciw DH. Role for cannabinoid receptors in human proximal tubular hypertrophy. Cell Physiol Biochem 2011; 26:879-86. [PMID: 21220919 DOI: 10.1159/000323997] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2010] [Indexed: 02/04/2023] Open
Abstract
Endogenous endocannabinoids bind to cannabinoid receptors; namely CB1, CB2, TRPV1 and GPR55, to activate intracellular pathways that control many cellular functions. Elevated levels of endocannabinoids have been identified in diseases such as obesity and diabetes, with the onset of diabetic nephropathy associated with proximal tubule hypertrophy. Recent research has identified a role for CB1 in apoptosis in human proximal tubular (HK2) cells, however the role of the other receptors has not been investigated. We investigated if the cannabinoid receptors played a role in hypertrophy in HK2 cells. Characterisation of HK2 cells demonstrated that mRNA and protein for CB1, CB2, TRPV1 and GPR55 occurs in these cells. Importantly, activation of the cannabinoid receptors with anandamide significantly increases hypertrophy in HK2 cells. In general, treatment with CB1 antagonist AM-251, reduces hypertrophy while treatment with CB2 (AM-630) and TRPV1 (SB-366791) antagonists increases hypertrophy. Targeting a cannabinoid receptor sensitive to O-1918 in HK2 cells did not alter proximal tubule cell hypertrophy. Therefore it is likely that in human proximal tubule, these receptors regulate cellular function by activating different cell signalling pathways. Nonetheless, we have identified a role for cannabinoid receptors in proximal tubule cells which may provide novel therapeutic targets for the treatment of diabetes and obesity.
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Affiliation(s)
- Kayte A Jenkin
- School of Biomedical and Health Sciences, Victoria University, St Albans Campus, Melbourne, Australia
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Polyamines are present in mast cell secretory granules and are important for granule homeostasis. PLoS One 2010; 5:e15071. [PMID: 21151498 PMCID: PMC2994821 DOI: 10.1371/journal.pone.0015071] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 10/19/2010] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Mast cell secretory granules accommodate a large number of components, many of which interact with highly sulfated serglycin proteoglycan (PG) present within the granules. Polyamines (putrescine, spermidine and spermine) are absolutely required for the survival of the vast majority of living cells. Given the reported ability of polyamines to interact with PGs, we investigated the possibility that polyamines may be components of mast cell secretory granules. METHODOLOGY/PRINCIPAL FINDINGS Spermidine was released by mouse bone marrow derived mast cells (BMMCs) after degranulation induced by IgE/anti-IgE or calcium ionophore A23187. Additionally, both spermidine and spermine were detected in isolated mouse mast cell granules. Further, depletion of polyamines by culturing BMMCs with α-difluoromethylornithine (DFMO) caused aberrant secretory granule ultrastructure, impaired histamine storage, reduced serotonin levels and increased β-hexosaminidase content. A proteomic approach revealed that DFMO-induced polyamine depletion caused an alteration in the levels of a number of proteins, many of which are connected either with the regulated exocytosis or with the endocytic system. CONCLUSIONS/SIGNIFICANCE Taken together, our results show evidence that polyamines are present in mast cell secretory granules and, furthermore, indicate an essential role of these polycations during the biogenesis and homeostasis of these organelles.
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Smith AJ, Lippiat JD. Direct endosomal acidification by the outwardly rectifying CLC-5 Cl(-)/H(+) exchanger. J Physiol 2010; 588:2033-45. [PMID: 20421284 PMCID: PMC2911210 DOI: 10.1113/jphysiol.2010.188540] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 04/23/2010] [Indexed: 01/27/2023] Open
Abstract
The voltage-gated Cl(-) channel (CLC) family comprises cell surface Cl(-) channels and intracellular Cl(-)/H(+) exchangers. CLCs in organelle membranes are thought to assist acidification by providing a passive chloride conductance that electrically counterbalances H(+) accumulation. Following recent descriptions of Cl(-)/H(+) exchange activity in endosomal CLCs we have re-evaluated their role. We expressed human CLC-5 in HEK293 cells, recorded currents under a range of Cl(-) and H(+) gradients by whole-cell patch clamp, and examined the contribution of CLC-5 to endosomal acidification using a targeted pH-sensitive fluorescent protein. We found that CLC-5 only conducted outward currents, corresponding to Cl(-) flux into the cytoplasm and H(+) from the cytoplasm. Inward currents were never observed, despite the range of intracellular and extracellular Cl(-) concentrations and pH used. Endosomal acidification in HEK293 cells was prevented by 25 microm bafilomycin-A1, an inhibitor of vacuolar-type H(+)-ATPase (v-ATPase), which actively pumps H(+) into the endosomal lumen. Overexpression of CLC-5 in HEK293 cells conferred an additional bafilomycin-insensitive component to endosomal acidification. This effect was abolished by making mutations in CLC-5 that remove H(+) transport, which result in either no current (E268A) or bidirectional Cl(-) flux (E211A). Endosomal acidification in a proximal tubule cell line was partially sensitive to inhibition of v-ATPase by bafilomycin-A1. Furthermore, in the presence of bafilomycin-A1, acidification was significantly reduced and nearly fully ablated by partial and near-complete knockdown of endogenous CLC-5 by siRNA. These data suggest that CLC-5 is directly involved in endosomal acidification by exchanging endosomal Cl(-) for H(+).
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Affiliation(s)
- Andrew J Smith
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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Novarino G, Weinert S, Rickheit G, Jentsch TJ. Endosomal chloride-proton exchange rather than chloride conductance is crucial for renal endocytosis. Science 2010; 328:1398-401. [PMID: 20430975 DOI: 10.1126/science.1188070] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Loss of the endosomal anion transport protein ClC-5 impairs renal endocytosis and underlies human Dent's disease. ClC-5 is thought to promote endocytosis by facilitating endosomal acidification through the neutralization of proton pump currents. However, ClC-5 is a 2 chloride (Cl-)/proton (H+) exchanger rather than a Cl- channel. We generated mice that carry the uncoupling E211A (unc) mutation that converts ClC-5 into a pure Cl- conductor. Adenosine triphosphate (ATP)-dependent acidification of renal endosomes was reduced in mice in which ClC-5 was knocked out, but normal in Clcn5(unc) mice. However, their proximal tubular endocytosis was also impaired. Thus, endosomal chloride concentration, which is raised by ClC-5 in exchange for protons accumulated by the H+-ATPase, may play a role in endocytosis.
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Affiliation(s)
- Gaia Novarino
- Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), 13125 Berlin, Germany
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Rickheit G, Wartosch L, Schaffer S, Stobrawa SM, Novarino G, Weinert S, Jentsch TJ. Role of ClC-5 in renal endocytosis is unique among ClC exchangers and does not require PY-motif-dependent ubiquitylation. J Biol Chem 2010; 285:17595-603. [PMID: 20351103 DOI: 10.1074/jbc.m110.115600] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Inactivation of the mainly endosomal 2Cl(-)/H(+)-exchanger ClC-5 severely impairs endocytosis in renal proximal tubules and underlies the human kidney stone disorder Dent's disease. In heterologous expression systems, interaction of the E3 ubiquitin ligases WWP2 and Nedd4-2 with a "PY-motif" in the cytoplasmic C terminus of ClC-5 stimulates its internalization from the plasma membrane and may influence receptor-mediated endocytosis. We asked whether this interaction is relevant in vivo and generated mice in which the PY-motif was destroyed by a point mutation. Unlike ClC-5 knock-out mice, these knock-in mice displayed neither low molecular weight proteinuria nor hyperphosphaturia, and both receptor-mediated and fluid-phase endocytosis were normal. The abundances and localizations of the endocytic receptor megalin and of the Na(+)-coupled phosphate transporter NaPi-2a (Npt2) were not changed, either. To explore whether the discrepancy in results from heterologous expression studies might be due to heteromerization of ClC-5 with ClC-3 or ClC-4 in vivo, we studied knock-in mice additionally deleted for those related transporters. Disruption of neither ClC-3 nor ClC-4 led to proteinuria or impaired proximal tubular endocytosis by itself, nor in combination with the PY-mutant of ClC-5. Endocytosis of cells lacking ClC-5 was not impaired further when ClC-3 or ClC-4 was additionally deleted. We conclude that ClC-5 is unique among CLC proteins in being crucial for proximal tubular endocytosis and that PY-motif-dependent ubiquitylation of ClC-5 is dispensable for this role.
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Affiliation(s)
- Gesa Rickheit
- Leibniz-Institut für Molekulare Pharmakologie and Max-Delbrück-Centrum für Molekulare Medizin, Robert-Rössle-Strasse 10, D-13125 Berlin, Germany
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ClC transporters: discoveries and challenges in defining the mechanisms underlying function and regulation of ClC-5. Pflugers Arch 2010; 460:543-57. [PMID: 20049483 DOI: 10.1007/s00424-009-0769-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 11/27/2009] [Accepted: 11/30/2009] [Indexed: 02/03/2023]
Abstract
The involvement of several members of the chloride channel (ClC) family of membrane proteins in human disease highlights the need to define the mechanisms underlying their function and the consequences of disease-causing mutations. Despite the utility of high-resolution structural models, our understanding of the molecular basis for function of the chloride channels and transporters in the family remains incomplete. In this review, we focus on recent discoveries regarding molecular mechanisms underlying the regulated chloride:proton antiporter activity of ClC-5, the protein mutated in the Dent's disease-a kidney disease presenting with proteinuria and renal failure in severe cases. We discuss the putative role of ClC-5 in receptor-mediated endocytosis and protein uptake by the proximal renal tubule and the possible molecular and cellular consequences of disease-causing mutations. However, validation of these models will require future study of the intrinsic function of this transporter, in situ, in the membranes of recycling endosomes in proximal tubule epithelial cells.
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Reed AAC, Loh NY, Terryn S, Lippiat JD, Partridge C, Galvanovskis J, Williams SE, Jouret F, Wu FTF, Courtoy PJ, Nesbit MA, Rorsman P, Devuyst O, Ashcroft FM, Thakker RV. CLC-5 and KIF3B interact to facilitate CLC-5 plasma membrane expression, endocytosis, and microtubular transport: relevance to pathophysiology of Dent's disease. Am J Physiol Renal Physiol 2009; 298:F365-80. [PMID: 19940036 PMCID: PMC2822520 DOI: 10.1152/ajprenal.00038.2009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Renal tubular reabsorption is important for extracellular fluid homeostasis and much of this occurs via the receptor-mediated endocytic pathway. This pathway is disrupted in Dent’s disease, an X-linked renal tubular disorder that is characterized by low-molecular-weight proteinuria, hypercalciuria, nephrolithiasis, and renal failure. Dent's disease is due to mutations of CLC-5, a chloride/proton antiporter, expressed in endosomes and apical membranes of renal tubules. Loss of CLC-5 function alters receptor-mediated endocytosis and trafficking of megalin and cubilin, although the underlying mechanisms remain to be elucidated. Here, we report that CLC-5 interacts with kinesin family member 3B (KIF3B), a heterotrimeric motor protein that facilitates fast anterograde translocation of membranous organelles. Using yeast two-hybrid, glutathione-S-transferase pull-down and coimmunoprecipitation assays, the COOH terminus of CLC-5 and the coiled-coil and globular domains of KIF3B were shown to interact. This was confirmed in vivo by endogenous coimmunoprecipitation of CLC-5 and KIF3B and codistribution with endosomal markers in mouse kidney fractions. Confocal live cell imaging in kidney cells further demonstrated association of CLC-5 and KIF3B, and transport of CLC-5-containing vesicles along KIF3B microtubules. KIF3B overexpression and underexpression, using siRNA, had reciprocal effects on whole cell chloride current amplitudes, CLC-5 cell surface expression, and endocytosis of albumin and transferrin. Clcn5Y/− mouse kidneys and isolated proximal tubular polarized cells showed increased KIF3B expression, whose effects on albumin endocytosis were dependent on CLC-5 expression. Thus, the CLC-5 and KIF3B interaction is important for CLC-5 plasma membrane expression and for facilitating endocytosis and microtubular transport in the kidney.
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Affiliation(s)
- Anita A C Reed
- Academic Endocrine Unit, Nuffield Department of Medicine, University of Oxford, Oxford Centre for Diabetes, Endocrinology, and Metabolism, Churchill Hospital, Oxford, United Kingdom
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Novel CLCN5 mutations in patients with Dent’s disease result in altered ion currents or impaired exchanger processing. Kidney Int 2009; 76:999-1005. [DOI: 10.1038/ki.2009.305] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kruger WA, Yun CC, Monteith GR, Poronnik P. Muscarinic-induced recruitment of plasma membrane Ca2+-ATPase involves PSD-95/Dlg/Zo-1-mediated interactions. J Biol Chem 2008; 284:1820-30. [PMID: 19017653 DOI: 10.1074/jbc.m804590200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Efflux of cytosolic Ca2+ mediated by plasma membrane Ca2+-ATPases (PMCA) plays a key role in fine tuning the magnitude and duration of Ca2+ signaling following activation of G-protein-coupled receptors. However, the molecular mechanisms that underpin the trafficking of PMCA to the membrane during Ca2+ signaling remain largely unexplored in native cell models. One potential mechanism for the recruitment of proteins to the plasma membrane involves PDZ interactions. In this context, we investigated the role of PMCA interactions with the Na+/H+ exchanger regulatory factor 2 (NHERF-2) during muscarinic-induced Ca2+ mobilization in the HT-29 epithelial cell line. GST pull-downs in HT-29 cell lysates showed that the PDZ2 module of NHERF-2 bound to the PDZ binding motif on the C terminus of PMCA. Co-immunoprecipitations confirmed that PMCA1b and NHERF-2 associated under normal conditions in HT-29 cells. Cell surface biotinylations revealed significant increases in membrane-associated NHERF-2 and PMCA within 60 s following muscarinic activation, accompanied by increased association of the two proteins as seen by confocal microscopy. The recruitment of NHERF-2 to the membrane preceded that of PMCA, suggesting that NHERF-2 was involved in nucleating an efflux complex at the membrane. The muscarinic-mediated translocation of PMCA was abolished when NHERF-2 was silenced, and the rate of relative Ca2+ efflux was also reduced. These experiments also uncovered a NHERF-2-independent PMCA retrieval mechanism. Our findings describe rapid agonist-induced translocation of PMCA in a native cell model and suggest that NHERF-2 plays a key role in scaffolding and maintaining PMCA at the cell membrane.
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Affiliation(s)
- Wade A Kruger
- School of Biomedical Sciences and School of Pharmacy, The University of Queensland, Brisbane QLD 4072, Australia
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Physiological roles of CLC Cl−/H+ exchangers in renal proximal tubules. Pflugers Arch 2008; 458:23-37. [DOI: 10.1007/s00424-008-0597-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 09/22/2008] [Accepted: 09/26/2008] [Indexed: 12/19/2022]
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Garmann D, Warnecke A, Kalayda GV, Kratz F, Jaehde U. Cellular accumulation and cytotoxicity of macromolecular platinum complexes in cisplatin-resistant tumor cells. J Control Release 2008; 131:100-6. [DOI: 10.1016/j.jconrel.2008.07.017] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2008] [Revised: 06/25/2008] [Accepted: 07/11/2008] [Indexed: 10/21/2022]
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Baugher PJ, Richmond A. The carboxyl-terminal PDZ ligand motif of chemokine receptor CXCR2 modulates post-endocytic sorting and cellular chemotaxis. J Biol Chem 2008; 283:30868-78. [PMID: 18755694 DOI: 10.1074/jbc.m804054200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Adaptor protein interaction with specific peptide motifs found within the intracellular, carboxyl terminus of chemokine receptor CXCR2 has been shown to modulate intracellular trafficking and receptor function. Efficient ligand-induced internalization of this receptor is dependent on the binding of adaptor protein 2 to the specific LLKIL motif found within the carboxyl terminus (1). In this study we show that the carboxyl-terminal type 1 PDZ ligand motif (-STTL) of CXCR2 plays an essential role in both proper intracellular receptor trafficking and efficient cellular chemotaxis. First, we show that CXCR2 is sorted to and degraded in the lysosome upon long-term ligand stimulation. We also show that receptor degradation is not dependent upon receptor ubiquitination, but is instead modulated by the carboxyl-terminal type I PDZ ligand of CXCR2. Deletion of this ligand results in increased degradation, earlier co-localization with the lysosome, and enhanced sorting to the Rab7-positive late endosome. We also show that deletion of this ligand effects neither receptor internalization nor receptor recycling. Furthermore, we demonstrate that deletion of the PDZ ligand motif results in impaired chemotactic response. The data presented here demonstrate that the type I PDZ ligand of CXCR2 acts to both delay lysosomal sorting and facilitate proper chemotactic response.
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Affiliation(s)
- Paige J Baugher
- Department of Veterans Affairs, Veterans Affairs Medical Center, Nashville, Tennessee 37212-2637, USA
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Jentsch TJ. CLC chloride channels and transporters: from genes to protein structure, pathology and physiology. Crit Rev Biochem Mol Biol 2008; 43:3-36. [PMID: 18307107 DOI: 10.1080/10409230701829110] [Citation(s) in RCA: 277] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
CLC genes are expressed in species from bacteria to human and encode Cl(-)-channels or Cl(-)/H(+)-exchangers. CLC proteins assemble to dimers, with each monomer containing an ion translocation pathway. Some mammalian isoforms need essential beta -subunits (barttin and Ostm1). Crystal structures of bacterial CLC Cl(-)/H(+)-exchangers, combined with transport analysis of mammalian and bacterial CLCs, yielded surprising insights into their structure and function. The large cytosolic carboxy-termini of eukaryotic CLCs contain CBS domains, which may modulate transport activity. Some of these have been crystallized. Mammals express nine CLC isoforms that differ in tissue distribution and subcellular localization. Some of these are plasma membrane Cl(-) channels, which play important roles in transepithelial transport and in dampening muscle excitability. Other CLC proteins localize mainly to the endosomal-lysosomal system where they may facilitate luminal acidification or regulate luminal chloride concentration. All vesicular CLCs may be Cl(-)/H(+)-exchangers, as shown for the endosomal ClC-4 and -5 proteins. Human diseases and knockout mouse models have yielded important insights into their physiology and pathology. Phenotypes and diseases include myotonia, renal salt wasting, kidney stones, deafness, blindness, male infertility, leukodystrophy, osteopetrosis, lysosomal storage disease and defective endocytosis, demonstrating the broad physiological role of CLC-mediated anion transport.
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Affiliation(s)
- Thomas J Jentsch
- Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany.
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Cunningham R, Esmaili A, Brown E, Biswas RS, Murtazina R, Donowitz M, Dijkman HB, van der Vlag J, Hogema BM, De Jonge HR, Shenolikar S, Wade JB, Weinman EJ. Urine electrolyte, mineral, and protein excretion in NHERF-2 and NHERF-1 null mice. Am J Physiol Renal Physiol 2008; 294:F1001-7. [PMID: 18256311 DOI: 10.1152/ajprenal.00504.2007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The adaptor proteins sodium/hydrogen exchanger regulatory factor (NHERF)-1 and NHERF-2 have overlapping tissue distribution in renal cells and overlapping specificity in their binding to renal transporters and other proteins. To compare the kidney-specific differences in the function of these adaptor proteins, NHERF-1 and NHERF-2 null mice were compared with wild-type control mice. In NHERF-2 null mice, the renal proximal tubule abundance and distribution of NHERF-1 and NHERF-3 were not different from those in wild-type animals. The glomerular expression of podocalyxin and ZO-1 also did not differ. NHERF-1 null mice had increased urinary excretion of phosphate, calcium, and uric acid compared with wild-type control and NHERF-2 null mice. Because of the association between NHERF-2 and podocalyxin in glomeruli and ClC-5 in the renal proximal tubule, the urinary excretion of protein was determined. There were no differences in the urinary excretion of protein or low-molecular-weight proteins between wild-type control, NHERF-1(-/-), and NHERF-2(-/-) mice. These studies indicate that the increased urinary excretion of phosphate and uric acid are specific to NHERF-1 null mice and highlight the fact that predictions about the role of adaptor proteins such as the NHERF proteins obtained from studies of model cell systems must be confirmed in whole animals.
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Affiliation(s)
- Rochelle Cunningham
- Univ. of Maryland School of Medicine, 22 S. Greene St., N3W143, Baltimore, MD 21201, USA.
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Khundmiri SJ, Ahmad A, Bennett RE, Weinman EJ, Steplock D, Cole J, Baumann PD, Lewis J, Singh S, Clark BJ, Lederer ED. Novel regulatory function for NHERF-1 in Npt2a transcription. Am J Physiol Renal Physiol 2008; 294:F840-9. [PMID: 18216150 DOI: 10.1152/ajprenal.00180.2007] [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
Several lines of evidence show that sodium/hydrogen exchanger regulatory factor 1 (NHERF-1) regulates the expression and activity of the type IIa sodium-dependent phosphate transporter (Npt2a) in renal proximal tubules. We have previously demonstrated that expression of a COOH-terminal ezrin binding domain-deficient NHERF-1 in opossum kidney (OK) cells decreased expression of Npt2a in apical membranes but did not affect responses to parathyroid hormone. We hypothesized that NHERF-1 regulates apical membrane expression of Npt2a in renal proximal tubule cells. To address this hypothesis, we compared regulation of Npt2a expression and function in NHERF-deficient OK cells (OK-H) and wild-type cells (OK-WT). In OK-H cells, phosphate uptake and expression of Npt2a protein in apical membranes were significantly lower than in OK-WT cells. Transient transfection of green fluorescent protein-tagged Npt2a cDNA into OK-H cells resulted in aberrant localization of an Npt2a fragment to the cytosol but not to the apical membrane. OK-H cells also exhibited a marked decrease in Npt2a mRNA expression. As demonstrated by luciferase assay, Npt2a promoter activity was significantly decreased in OK-H cells compared with that shown in OK-WT cells. Transfection of OK-H cells with human NHERF-1 restored Npt2a expression at both the protein and mRNA levels and regulation by parathyroid hormone. Expression of NHERF-1 constructs with mutations in the PDZ domains or the ezrin binding domain in OK-H cells suggested that the PDZ2 domain is critical for apical translocation of Npt2a and for expression at the mRNA level. Our data demonstrate for the first time that NHERF-1 regulates Npt2a transcription and membrane insertion.
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Affiliation(s)
- Syed Jalal Khundmiri
- Department of Medicine, Univ. of Louisville, Kidney Disease Program, 570 S. Preston St, Suite 102, Louisville, KY 40202, USA
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Current World Literature. Curr Opin Nephrol Hypertens 2007; 16:388-93. [PMID: 17565283 DOI: 10.1097/mnh.0b013e3282472fd5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Pollock CA, Poronnik P. Albumin transport and processing by the proximal tubule: physiology and pathophysiology. Curr Opin Nephrol Hypertens 2007; 16:359-64. [PMID: 17565279 DOI: 10.1097/mnh.0b013e3281eb9059] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE OF REVIEW Significant epidemiological and clinical trial evidence supports the association between increased urinary albumin excretion, cardiovascular events and renal failure. An increase in albumin excretion has traditionally been considered to reflect a 'glomerular' leak of protein; however, it is now recognized that significant tubular reabsorption of albumin occurs under physiological conditions that may be modified by genetic determinants, systemic disease and drug therapies. RECENT FINDINGS The endocytosis of albumin by the proximal tubule is a highly regulated process depending on protein-protein interactions between several membrane proteins and scaffolding and regulatory molecules. The elucidation of these interactions is an ongoing research focus. There is also mounting evidence for a transcytotic pathway for retrieval of albumin from the tubular filtrate. The molecular basis for the role of albuminuria in both interstitial renal disease and cardiovascular pathology continues to be defined. The clinical implications of albuminuria due to a glomerular leak vs. reduced tubular reabsorption of albumin are, however, now under consideration. In particular, the prognostic implication of microalbuminuria induced by the more potent 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors is under study. SUMMARY The currently defined mechanisms underpinning the tubular reabsorption of albumin, how these are modified by pathology and pharmacology, and the clinical implications are the subject of this review.
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Affiliation(s)
- Carol A Pollock
- Department of Medicine, University of Sydney, Kolling Institute, Royal North Shore Hospital, New South Wales, Australia.
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Abstract
NHE3 is the brush-border (BB) Na+/H+exchanger of small intestine, colon, and renal proximal tubule which is involved in large amounts of neutral Na+absorption. NHE3 is a highly regulated transporter, being both stimulated and inhibited by signaling that mimics the postprandial state. It also undergoes downregulation in diarrheal diseases as well as changes in renal disorders. For this regulation, NHE3 exists in large, multiprotein complexes in which it associates with at least nine other proteins. This review deals with short-term regulation of NHE3 and the identity and function of its recognized interacting partners and the multiprotein complexes in which NHE3 functions.
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Affiliation(s)
- Mark Donowitz
- Department of Medicine, GI Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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Schmieder S, Bogliolo S, Ehrenfeld J. N-glycosylation of the Xenopus laevis ClC-5 protein plays a role in cell surface expression, affecting transport activity at the plasma membrane. J Cell Physiol 2007; 210:479-88. [PMID: 17111367 DOI: 10.1002/jcp.20882] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Mutations in the gene encoding ClC-5 lead to X-linked hypercalciuric nephrolithiasis (XLHN), characterized by proteinuria, hypercalciuria, and phosphaturia. In renal proximal tubule cells, ClC-5 was identified as an important player in endocytosis, which ensures reabsorption of filtered protein. However, the recent finding that ClC-5 is a Cl(-)/H(+) antiporter and not a Cl(-) channel as long thought points to the lack of understanding of its functional role. Also, little biochemical data are available about ClC-5 and its post-translational modifications have not been investigated. Here, we examined the role of N-glycosylation of xClC-5 in the Xenopus oocyte expression system by comparing wild-type (WT) xClC-5 and N-glycosylation site mutants. We found that xClC-5 is N-glycosylated on asparagines 169 and 470, which are the only N-glycosylated sites. xClC-5 mutants have an increased susceptibility to polyubiquitination and proteasomal degradation; however, without a notable impact on the expression level. Using a cross-linking reagent, we showed that xClC-5 assembles into protein complexes, independent of its N-glycosylation. Voltage-clamp measurements showed a reduced conductance in the presence of tunicamycin and with xClC-5 N-glycosylation site mutants. Using immunocytochemistry, we localized xClC-5 mainly in intracellular compartments, and found that its cell surface pool is reduced in the absence of N-glycans. We further examined the plasma membrane retrieval of WT and mutant xClC-5 in the presence of Brefeldin A (BFA), and found that the non-glycosylated mutant was retrieved more than five times faster than the WT protein. We conclude that N-glycosylation enhances cell surface expression of xClC-5, increasing its plasma membrane transport activity.
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Affiliation(s)
- Sandra Schmieder
- Laboratoire de Physiologie Cellulaire et Moléculaire Des Systèmes Intégrés, Université de Nice-Sophia Antipolis/CNRS, UMR 6548, Nice, France
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Ramos-Trujillo E, González-Acosta H, Flores C, García-Nieto V, Guillén E, Gracia S, Vicente C, Espinosa L, Maseda MAF, Santos F, Camacho JA, Claverie-Martín F. A missense mutation in the chloride/proton ClC-5 antiporter gene results in increased expression of an alternative mRNA form that lacks exons 10 and 11. Identification of seven new CLCN5 mutations in patients with Dent’s disease. J Hum Genet 2007; 52:255-261. [PMID: 17262170 DOI: 10.1007/s10038-007-0112-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Accepted: 12/20/2006] [Indexed: 10/23/2022]
Abstract
Mutations in the voltage-gated chloride/proton antiporter ClC-5 gene, CLCN5, are associated with Dent's disease, an X-linked renal tubulopathy. Our interest is to identify and characterize disease-causing CLCN5 mutations, especially those that alter the splicing of the pre-mRNA. We analyzed the CLCN5 gene from nine unrelated Spanish Dent's disease patients and their relatives by DNA sequencing. Pre-mRNA splicing analysis was performed by RT-PCR. Seven new mutations were identified, consisting of three missense mutations (C219R, F273L, and W547G), one splice-site mutation (IVS-2A > G), one deletion (976delG), and two non-sense mutations (Y140X and W314X). We found that missense mutation W547G also led to increased expression of a new alternative isoform lacking exons 10 and 11 that was expressed in several human tissues. In addition, we describe another novel CLCN5 splicing variant lacking exon 11 alone, which was expressed only in human skeletal muscle. We conclude that missense mutation W547G can also alter the expression levels of a CLCN5 mRNA splicing variant. This type of mutation has not been previously described in the CLCN5 gene. Our results support the importance of a routine analysis at the pre-mRNA level of mutations that are commonly assumed to cause single amino acids alterations.
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Affiliation(s)
- Elena Ramos-Trujillo
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Hilaria González-Acosta
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Carlos Flores
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Víctor García-Nieto
- Unidad de Nefrología Pediátrica, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Encarna Guillén
- Servicio de Pediatría, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Salvador Gracia
- Servicio de Pediatría, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Carmen Vicente
- Servicio de Pediatría, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain
| | - Laura Espinosa
- Servicio de Nefrología Infantil, Hospital Universitario La Paz, Madrid, Spain
| | | | - Fernando Santos
- Servicio de Nefrología Pediátrica, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Juan A Camacho
- Sección de Nefrología, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Félix Claverie-Martín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
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Zifarelli G, Pusch M. CLC chloride channels and transporters: a biophysical and physiological perspective. Rev Physiol Biochem Pharmacol 2007; 158:23-76. [PMID: 17729441 DOI: 10.1007/112_2006_0605] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Chloride-transporting proteins play fundamental roles in many tissues in the plasma membrane as well as in intracellular membranes. They have received increasing attention in the last years because crucial, and often unexpected and novel, physiological functions have been disclosed with gene-targeting approaches, X-ray crystallography, and biophysical analysis. CLC proteins form a gene family that comprises nine members in mammals, at least four of which are involved in human genetic diseases. The X-ray structure of the bacterial CLC homolog, ClC-ec1, revealed a complex fold and confirmed the anticipated homodimeric double-barreled architecture of CLC-proteins with two separate Cl-ion transport pathways, one in each subunit. Four of the mammalian CLC proteins, ClC-1, ClC-2, ClC-Ka, and ClC-Kb, are chloride ion channels that fulfill their functional roles-stabilization of the membrane potential, transepithelial salt transport, and ion homeostasisin the plasma membrane. The other five CLC proteins are predominantly expressed in intracellular organelles like endosomes and lysosomes, where they are probably important for a proper luminal acidification, in concert with the V-type H+-ATPase. Surprisingly, ClC-4, ClC-5, and probably also ClC-3, are not Cl- ion channels but exhibit significant Cl-/H+ antiporter activity, as does the bacterial homolog ClC-ec1 and the plant homolog AtCLCa. The physiological significance of the Cl-/H+ antiport activity remains to be established.
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Affiliation(s)
- G Zifarelli
- CNR, Istituto di Biofisica, Via De Marini 6, 16149 Genova, Italy
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