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Zhang J, Yuan H, Yao X, Chen S. Endogenous ion channels expressed in human embryonic kidney (HEK-293) cells. Pflugers Arch 2022; 474:665-680. [PMID: 35567642 DOI: 10.1007/s00424-022-02700-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/25/2022] [Accepted: 04/30/2022] [Indexed: 12/21/2022]
Abstract
Mammalian expression systems, particularly the human embryonic kidney (HEK-293) cells, combined with electrophysiological studies, have greatly benefited our understanding of the function, characteristic, and regulation of various ion channels. It was previously assumed that the existence of endogenous ion channels in native HEK-293 cells could be negligible. Still, more and more ion channels are gradually reported in native HEK-293 cells, which should draw our attention. In this regard, we summarize the different ion channels that are endogenously expressed in HEK-293 cells, including voltage-gated Na+ channels, Ca2+ channels, K+ channels, Cl- channels, nonselective cation channels, TRP channels, acid-sensitive ion channels, and Piezo channels, which may complicate the recording of the heterogeneously expressed ion channels to a certain degree. We noted that the expression patterns and channel profiles varied with different studies, which may be due to the distinct originality of the cells, cell culture conditions, passage numbers, and different recording protocols. Therefore, a better knowledge of endogenous ion channels may help minimize potential problems in characterizing heterologously expressed ion channels. Based on this, it is recommended that HEK-293 cells from unknown sources should be examined before transfection for the characterization of their functional profile, especially when the expression level of exogenous ion channels does not overwhelm the endogenous ion channels largely, or the current amplitude is not significantly higher than the native currents.
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Affiliation(s)
- Jun Zhang
- School of Biomedical Sciences and Li Ka Shing Institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China
| | - Huikai Yuan
- Department of General Surgery, The First Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Xiaoqiang Yao
- School of Biomedical Sciences and Li Ka Shing Institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China
| | - Shuo Chen
- Department of Biopharmaceutical Sciences, School of Pharmacy, Harbin Medical University at Daqing, No. 39 Xinyang Rd, High-tech District, Daqing, 163319, Heilongjiang Province, China.
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2
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Thompson CL, McFie M, Chapple JP, Beales P, Knight MM. Polycystin-2 Is Required for Chondrocyte Mechanotransduction and Traffics to the Primary Cilium in Response to Mechanical Stimulation. Int J Mol Sci 2021; 22:4313. [PMID: 33919210 PMCID: PMC8122406 DOI: 10.3390/ijms22094313] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/10/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022] Open
Abstract
Primary cilia and associated intraflagellar transport are essential for skeletal development, joint homeostasis, and the response to mechanical stimuli, although the mechanisms remain unclear. Polycystin-2 (PC2) is a member of the transient receptor potential polycystic (TRPP) family of cation channels, and together with Polycystin-1 (PC1), it has been implicated in cilia-mediated mechanotransduction in epithelial cells. The current study investigates the effect of mechanical stimulation on the localization of ciliary polycystins in chondrocytes and tests the hypothesis that they are required in chondrocyte mechanosignaling. Isolated chondrocytes were subjected to mechanical stimulation in the form of uniaxial cyclic tensile strain (CTS) in order to examine the effects on PC2 ciliary localization and matrix gene expression. In the absence of strain, PC2 localizes to the chondrocyte ciliary membrane and neither PC1 nor PC2 are required for ciliogenesis. Cartilage matrix gene expression (Acan, Col2a) is increased in response to 10% CTS. This response is inhibited by siRNA-mediated loss of PC1 or PC2 expression. PC2 ciliary localization requires PC1 and is increased in response to CTS. Increased PC2 cilia trafficking is dependent on the activation of transient receptor potential cation channel subfamily V member 4 (TRPV4) activation. Together, these findings demonstrate for the first time that polycystins are required for chondrocyte mechanotransduction and highlight the mechanosensitive cilia trafficking of PC2 as an important component of cilia-mediated mechanotransduction.
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Affiliation(s)
- Clare L. Thompson
- Centre for Predictive In Vitro Models, School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (M.M.); (M.M.K.)
| | - Megan McFie
- Centre for Predictive In Vitro Models, School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (M.M.); (M.M.K.)
| | - J. Paul Chapple
- Centre for Endocrinology, William Harvey Research Institute, School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK;
| | - Philip Beales
- Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK;
| | - Martin M. Knight
- Centre for Predictive In Vitro Models, School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (M.M.); (M.M.K.)
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Belmonte JM, Clendenon SG, Oliveira GM, Swat MH, Greene EV, Jeyaraman S, Glazier JA, Bacallao RL. Virtual-tissue computer simulations define the roles of cell adhesion and proliferation in the onset of kidney cystic disease. Mol Biol Cell 2016; 27:3673-3685. [PMID: 27193300 PMCID: PMC5221598 DOI: 10.1091/mbc.e16-01-0059] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/10/2016] [Indexed: 12/15/2022] Open
Abstract
Virtual-tissue modeling is used to model emergent cyst growth in polycystic kidney disease. Model predictions, confirmed experimentally, show that decreased cell adhesion is necessary to produce stalk cysts, and loss of contact inhibition causes saccular cysts. Virtual-tissue modeling can be used to fully explore cell- and tissue-based behaviors. In autosomal dominant polycystic kidney disease (ADPKD), cysts accumulate and progressively impair renal function. Mutations in PKD1 and PKD2 genes are causally linked to ADPKD, but how these mutations drive cell behaviors that underlie ADPKD pathogenesis is unknown. Human ADPKD cysts frequently express cadherin-8 (cad8), and expression of cad8 ectopically in vitro suffices to initiate cystogenesis. To explore cell behavioral mechanisms of cad8-driven cyst initiation, we developed a virtual-tissue computer model. Our simulations predicted that either reduced cell–cell adhesion or reduced contact inhibition of proliferation triggers cyst induction. To reproduce the full range of cyst morphologies observed in vivo, changes in both cell adhesion and proliferation are required. However, only loss-of-adhesion simulations produced morphologies matching in vitro cad8-induced cysts. Conversely, the saccular cysts described by others arise predominantly by decreased contact inhibition, that is, increased proliferation. In vitro experiments confirmed that cell–cell adhesion was reduced and proliferation was increased by ectopic cad8 expression. We conclude that adhesion loss due to cadherin type switching in ADPKD suffices to drive cystogenesis. Thus, control of cadherin type switching provides a new target for therapeutic intervention.
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Affiliation(s)
- Julio M Belmonte
- Biocomplexity Institute, Physics Department, Indiana University, Bloomington, IN 47405
| | - Sherry G Clendenon
- Biocomplexity Institute, Physics Department, Indiana University, Bloomington, IN 47405
| | - Guilherme M Oliveira
- Biocomplexity Institute, Physics Department, Indiana University, Bloomington, IN 47405
| | - Maciej H Swat
- Biocomplexity Institute, Physics Department, Indiana University, Bloomington, IN 47405
| | - Evan V Greene
- Division of Nephrology, Richard L. Roudebush VA Medical Center, and Indiana University School of Medicine, Indianapolis, IN 46202
| | - Srividhya Jeyaraman
- Biocomplexity Institute, Physics Department, Indiana University, Bloomington, IN 47405
| | - James A Glazier
- Biocomplexity Institute, Physics Department, Indiana University, Bloomington, IN 47405
| | - Robert L Bacallao
- Division of Nephrology, Richard L. Roudebush VA Medical Center, and Indiana University School of Medicine, Indianapolis, IN 46202
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4
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Chebib FT, Sussman CR, Wang X, Harris PC, Torres VE. Vasopressin and disruption of calcium signalling in polycystic kidney disease. Nat Rev Nephrol 2015; 11:451-64. [PMID: 25870007 PMCID: PMC4539141 DOI: 10.1038/nrneph.2015.39] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic kidney disease and is responsible for 5-10% of cases of end-stage renal disease worldwide. ADPKD is characterized by the relentless development and growth of cysts, which cause progressive kidney enlargement associated with hypertension, pain, reduced quality of life and eventual kidney failure. Mutations in the PKD1 or PKD2 genes, which encode polycystin-1 (PC1) and polycystin-2 (PC2), respectively, cause ADPKD. However, neither the functions of these proteins nor the molecular mechanisms of ADPKD pathogenesis are well understood. Here, we review the literature that examines how reduced levels of functional PC1 or PC2 at the primary cilia and/or the endoplasmic reticulum directly disrupts intracellular calcium signalling and indirectly disrupts calcium-regulated cAMP and purinergic signalling. We propose a hypothetical model in which dysregulated metabolism of cAMP and purinergic signalling increases the sensitivity of principal cells in collecting ducts and of tubular epithelial cells in the distal nephron to the constant tonic action of vasopressin. The resulting magnified response to vasopressin further enhances the disruption of calcium signalling that is initiated by mutations in PC1 or PC2, and activates downstream signalling pathways that cause impaired tubulogenesis, increased cell proliferation, increased fluid secretion and interstitial inflammation.
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Affiliation(s)
- Fouad T Chebib
- Division of Nephrology and Hypertension, 200 First Street S. W., Mayo Clinic College of Medicine, Rochester, MN 55901, USA
| | - Caroline R Sussman
- Division of Nephrology and Hypertension, 200 First Street S. W., Mayo Clinic College of Medicine, Rochester, MN 55901, USA
| | - Xiaofang Wang
- Division of Nephrology and Hypertension, 200 First Street S. W., Mayo Clinic College of Medicine, Rochester, MN 55901, USA
| | - Peter C Harris
- Division of Nephrology and Hypertension, 200 First Street S. W., Mayo Clinic College of Medicine, Rochester, MN 55901, USA
| | - Vicente E Torres
- Division of Nephrology and Hypertension, 200 First Street S. W., Mayo Clinic College of Medicine, Rochester, MN 55901, USA
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Mangolini A, Bonon A, Volinia S, Lanza G, Gambari R, Pinton P, Russo GR, del Senno L, Dell’Atti L, Aguiari G. Differential expression of microRNA501-5p affects the aggressiveness of clear cell renal carcinoma. FEBS Open Bio 2014; 4:952-65. [PMID: 25426415 PMCID: PMC4241533 DOI: 10.1016/j.fob.2014.10.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/09/2014] [Accepted: 10/28/2014] [Indexed: 12/18/2022] Open
Abstract
Low expression of miR501-5p correlates with good prognosis for patients with ccRCC. miRNA501-5p downregulation stimulates apoptosis by p53 activation. miR501-5p upregulation promotes cell proliferation and survival. Increased cell growth occurs by activation of mTOR kinase and MDM2 expression. This miRNA modulates apoptosis/cell growth, making it a prognostic biomarker for ccRCC.
Renal cell carcinoma is a common neoplasia of the adult kidney that accounts for about 3% of adult malignancies. Clear cell renal carcinoma is the most frequent subtype of kidney cancer and 20–40% of patients develop metastases. The absence of appropriate biomarkers complicates diagnosis and prognosis of this disease. In this regard, small noncoding RNAs (microRNAs), which are mutated in several neoplastic diseases including kidney carcinoma, may be optimal candidates as biomarkers for diagnosis and prognosis of this kind of cancer. Here we show that patients with clear cell kidney carcinoma that express low levels of miR501-5p exhibited a good prognosis compared with patients with unchanged or high levels of this microRNA. Consistently, in kidney carcinoma cells the downregulation of miR501-5p induced an increased caspase-3 activity, p53 expression as well as decreased mTOR activation, leading to stimulation of the apoptotic pathway. Conversely, miR501-5p upregulation enhanced the activity of mTOR and promoted both cell proliferation and survival. These biological processes occurred through p53 inactivation by proteasome degradation in a mechanism involving MDM2-mediated p53 ubiquitination. Our results support a role for miR501-5p in balancing apoptosis and cell survival in clear cell renal carcinoma. In particular, the downregulation of microRNA501-5p promotes a good prognosis, while its upregulation contributes to a poor prognosis, in particular, if associated with p53 and MDM2 overexpression and mTOR activation. Thus, the expression of miR501-5p is a possible biomarker for the prognosis of clear cell renal carcinoma.
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Affiliation(s)
- Alessandra Mangolini
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, University of Ferrara, Via Fossato di Mortara 64/b, 44121 Ferrara, Italy
| | - Anna Bonon
- Department of Biomedical and Specialty Surgical Sciences, Section of Biochemistry, Molecular Biology and Medical Genetics, University of Ferrara, Via Fossato di Mortara 74, 44121 Ferrara, Italy
| | - Stefano Volinia
- Department of Morphology, Surgery and Experimental Medicine, Section of Anatomy and Histology, University of Ferrara, Via Fossato di Mortara 64/b, 44121 Ferrara, Italy
| | - Giovanni Lanza
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathological Anatomy and Biomolecular Diagnostic, Azienda Ospedaliero Universitaria, Via Aldo Moro 8, 44124 Ferrara, Italy
| | - Roberto Gambari
- Department of Life Sciences and Biotechnologies, Section of Molecular Biology, University of Ferrara, Via Fossato di Mortara 74, 44121 Ferrara, Italy
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, University of Ferrara, Via Fossato di Mortara 64/b, 44121 Ferrara, Italy
| | - Gian Rosario Russo
- Unit of Urology, St. Anna Hospital, Via Aldo Moro 8, 44124 Ferrara, Italy
| | - Laura del Senno
- Department of Biomedical and Specialty Surgical Sciences, Section of Biochemistry, Molecular Biology and Medical Genetics, University of Ferrara, Via Fossato di Mortara 74, 44121 Ferrara, Italy
| | - Lucio Dell’Atti
- Unit of Urology, St. Anna Hospital, Via Aldo Moro 8, 44124 Ferrara, Italy
| | - Gianluca Aguiari
- Department of Biomedical and Specialty Surgical Sciences, Section of Biochemistry, Molecular Biology and Medical Genetics, University of Ferrara, Via Fossato di Mortara 74, 44121 Ferrara, Italy
- Corresponding author. Tel.: +39 0532974460; fax: +39 0532974484.
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Berberine slows cell growth in autosomal dominant polycystic kidney disease cells. Biochem Biophys Res Commun 2013; 441:668-74. [PMID: 24184483 DOI: 10.1016/j.bbrc.2013.10.076] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 10/15/2013] [Indexed: 12/12/2022]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary monogenic disorder characterized by development and enlargement of kidney cysts that lead to loss of renal function. It is caused by mutations in two genes (PKD1 and PKD2) encoding for polycystin-1 and polycystin-2 proteins which regulate different signals including cAMP, mTOR and EGFR pathways. Abnormal activation of these signals following PC1 or PC2 loss of function causes an increased cell proliferation which is a typical hallmark of this disease. Despite the promising findings obtained in animal models with targeted inhibitors able to reduce cystic cell growth, currently, no specific approved therapy for ADPKD is available. Therefore, the research of new more effective molecules could be crucial for the treatment of this severe pathology. In this regard, we have studied the effect of berberine, an isoquinoline quaternary alkaloid, on cell proliferation and apoptosis in human and mouse ADPKD cystic cell lines. Berberine treatment slows cell proliferation of ADPKD cystic cells in a dose-dependent manner and at high doses (100 μg/mL) it induces cell death in cystic cells as well as in normal kidney tubule cells. However, at 10 μg/mL, berberine reduces cell growth in ADPKD cystic cells only enhancing G0/G1 phase of cell cycle and inhibiting ERK and p70-S6 kinases. Our results indicate that berberine shows a selected antiproliferative activity in cellular models for ADPKD, suggesting that this molecule and similar natural compounds could open new opportunities for the therapy of ADPKD patients.
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Aguiari G, Bizzarri F, Bonon A, Mangolini A, Magri E, Pedriali M, Querzoli P, Somlo S, Harris PC, Catizone L, Del Senno L. Polycystin-1 regulates amphiregulin expression through CREB and AP1 signalling: implications in ADPKD cell proliferation. J Mol Med (Berl) 2012; 90:1267-82. [PMID: 22570239 DOI: 10.1007/s00109-012-0902-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 03/26/2012] [Accepted: 04/04/2012] [Indexed: 01/08/2023]
Abstract
In autosomal dominant polycystic kidney disease (ADPKD), renal cyst development and enlargement, as well as cell growth, are associated with alterations in several pathways, including cAMP and activator protein 1 (AP1) signalling. However, the precise mechanism by which these molecules stimulate cell proliferation is not yet fully understood. We now show by microarray analysis, luciferase assay, mutagenesis, and chromatin immunoprecipitation that CREB and AP1 contribute to increased expression of the amphiregulin gene, which codifies for an epidermal growth factor-like peptide, in ADPKD cystic cells, thereby promoting their cell growth. Increased amphiregulin (AR) expression was associated with abnormal cell proliferation in both PKD1-depleted and -mutated epithelial cells, as well as primary cystic cell lines isolated from ADPKD kidney tissues. Consistently, normal AR expression and proliferation were re-established in cystic cells by the expression of a mouse full-length PC1. Finally, we show that anti-AR antibodies and inhibitors of AP1 are able to reduce cell proliferation in cystic cells by reducing AR expression and EGFR activity. AR can therefore be considered as one of the key activators of the growth of human ADPKD cystic cells and thus a new potential therapeutic target.
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Affiliation(s)
- Gianluca Aguiari
- Department of Biochemistry and Molecular Biology, University of Ferrara, via Fossato di Mortara, 74, 44121 Ferrara, Italy.
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NF-kappaB activation is required for apoptosis in fibrocystin/polyductin-depleted kidney epithelial cells. Apoptosis 2010; 15:94-104. [PMID: 19943112 DOI: 10.1007/s10495-009-0426-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Autosomal recessive polycystic kidney disease (ARPKD) is caused by mutations in PKHD1, a gene encoding fibrocystin/polyductin (FC1), a membrane-associated receptor-like protein involved in the regulation of tubular cell adhesion, proliferation and apoptosis. Although it is generally accepted that apoptosis is implicated in ARPKD, the question of whether increased apoptosis is a normal response to abnormal cell proliferation or, instead, it is a primary event, is still subject to debate. In support of the latter hypothesis, we hereby provide evidence that apoptosis occurs in the absence of hyper-proliferation of FC1-depleted kidney cells. In fact, a decrease in cell proliferation, with a concomitant increase in apoptotic index and caspase-3 activity was observed in response to FC1-depletion by PKHD1 siRNA silencing in HEK293 and 4/5 tubular cells. FC1-depletion also induced reduction in ERK1/2 kinase activation, upregulation of the pro-apoptotic protein p53 and activation of NF-kappaB, a transcription factor which reduces apoptosis in many organs and tissues. Interestingly, selective inactivation of NF-kappaB using either an NF-kappaB decoy or parthenolide, a blocker of IKK-dependent NF-kappaB activation, reduced, rather then increased, apoptosis and p53 levels in FC1-depleted cells. Therefore, the proapoptotic function of NF-kappaB during cell death by FC1-depletion in kidney cells is evident.
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SPIRLI CARLO, OKOLICSANYI STEFANO, FIOROTTO ROMINA, FABRIS LUCA, CADAMURO MASSIMILIANO, LECCHI SILVIA, TIAN XIN, SOMLO STEFAN, STRAZZABOSCO MARIO. ERK1/2-dependent vascular endothelial growth factor signaling sustains cyst growth in polycystin-2 defective mice. Gastroenterology 2010; 138:360-371.e7. [PMID: 19766642 PMCID: PMC3000794 DOI: 10.1053/j.gastro.2009.09.005] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2008] [Revised: 09/04/2009] [Accepted: 09/09/2009] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Severe polycystic liver disease can complicate adult dominant polycystic kidney disease, a genetic disease caused by defects in polycystin-1 (Pkd1) or polycystin-2 (Pkd2). Liver cyst epithelial cells (LCECs) express vascular endothelial growth factor (VEGF) and its receptor, VEGFR-2. We investigated the effects of VEGF on liver cyst growth and autocrine VEGF signaling in mice with Pkd1 and Pkd2 conditional knockouts. METHODS We studied mice in which Pkd1 or Pkd2 were conditionally inactivated following exposure to tamoxifen; these mice were called Pkd1(flox/-):pCxCreER (Pkd1KO) and Pkd2(flox/-):pCxCreER (Pkd2KO). RESULTS Pkd1KO and Pkd2KO mice developed liver defects; their LCECs expressed VEGF, VEGFR-2, hypoxia-inducible factor (HIF)-1alpha, phosphorylated extracellular signal-regulated kinase 1/2 (pERK1/2), and proliferating cell nuclear antigen (PCNA). In Pkd2KO but not Pkd1KO mice, exposure to the VEGFR-2 inhibitor SU5416 significantly reduced liver cyst development, liver/body weight ratio, and expression of pERK and PCNA. VEGF secretion and phosphorylation of ERK1/2 and VEGFR-2 were significantly increased in cultured LCECs from Pkd2KO compared with Pkd1KO mice. Inhibition of protein kinase A (PKA) reduced VEGF secretion and pERK1/2 expression. Addition of VEGF to LCECs from Pkd2KO mice increased phosphorylated VEGFR-2 and phosphorylated mitogen signal-regulated kinase (MEK) expression and induced phosphorylation of ERK1/2; this was inhibited by SU5416. Expression of HIF-1alpha increased in parallel with secretion of VEGF following LCEC stimulation. VEGF-induced cell proliferation was inhibited by the MEK inhibitor U1026 and by ERK1/2 small interfering RNA. CONCLUSIONS The PKA-ERK1/2-VEGF signaling pathway promotes growth of liver cysts in mice. In Pkd2-defective LCECs, PKA-dependent ERK1/2 signaling controls HIF-1alpha-dependent VEGF secretion and VEGFR-2 signaling. Autocrine and paracrine VEGF signaling promotes the growth of liver cysts in Pkd2KO mice. VEGF inhibitors might be used to treat patients with polycystic liver disease.
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Affiliation(s)
- CARLO SPIRLI
- Section of Digestive Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut,Center for Liver Research (CeLiveR), Ospedali Riuniti di Bergamo, Bergamo, Italy
| | - STEFANO OKOLICSANYI
- Section of Digestive Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut,Center for Liver Research (CeLiveR), Ospedali Riuniti di Bergamo, Bergamo, Italy
| | - ROMINA FIOROTTO
- Section of Digestive Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut,Center for Liver Research (CeLiveR), Ospedali Riuniti di Bergamo, Bergamo, Italy
| | - LUCA FABRIS
- Center for Liver Research (CeLiveR), Ospedali Riuniti di Bergamo, Bergamo, Italy
| | | | - SILVIA LECCHI
- Section of Digestive Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut,Center for Liver Research (CeLiveR), Ospedali Riuniti di Bergamo, Bergamo, Italy
| | - XIN TIAN
- Section of Nephrology, Department of Internal Medicine, Yale University, New Haven, Connecticut
| | - STEFAN SOMLO
- Section of Nephrology, Department of Internal Medicine, Yale University, New Haven, Connecticut
| | - MARIO STRAZZABOSCO
- Section of Digestive Diseases, Department of Internal Medicine, Yale University, New Haven, Connecticut,Center for Liver Research (CeLiveR), Ospedali Riuniti di Bergamo, Bergamo, Italy,Department of Clinical Medicine, University of Milano-Bicocca, Milan, Italy
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10
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Turner CM, Elliott JI, Tam FWK. P2 receptors in renal pathophysiology. Purinergic Signal 2009; 5:513-20. [PMID: 19507052 PMCID: PMC2776141 DOI: 10.1007/s11302-009-9153-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2006] [Accepted: 03/23/2008] [Indexed: 12/27/2022] Open
Abstract
Our knowledge and understanding of the P2 receptor signalling system in the kidney have increased significantly in the last ten years. The broad range of physiological roles proposed for this receptor system and the variety of P2 receptor subtypes found in the kidney suggest that any disturbance of function may contribute to several pathological processes. So far, most reports of a possible pathophysiological role for this system in the kidney have focussed on polycystic kidney disease, where abnormal P2 receptor signalling might be involved in cyst expansion and disease progression, and on the P2X(7) receptor, a unique P2X subtype, which when activated enhances inflammatory cytokine release and production, and also cell death. Expression of this particular receptor is upregulated in some forms of chronic renal injury and inflammatory diseases. Further studies of adenosine triphosphate signalling and P2 receptor expression in renal disorders could provide us with novel insights into the role of these receptors in both normal and abnormal kidney function.
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Affiliation(s)
- Clare M Turner
- Imperial College Kidney and Transplant Institute, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK,
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11
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Li Y, Santoso NG, Yu S, Woodward OM, Qian F, Guggino WB. Polycystin-1 interacts with inositol 1,4,5-trisphosphate receptor to modulate intracellular Ca2+ signaling with implications for polycystic kidney disease. J Biol Chem 2009; 284:36431-36441. [PMID: 19854836 DOI: 10.1074/jbc.m109.068916] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The PKD1 or PKD2 genes encode polycystins (PC) 1 and 2, which are associated with polycystic kidney disease. Previously we demonstrated that PC2 interacts with the inositol 1,4,5-trisphosphate receptor (IP(3)R) to modulate Ca(2+) signaling. Here, we investigate whether PC1 also regulates IP(3)R. We generated a fragment encoding the last six transmembrane (TM) domains of PC1 and the C-terminal tail (QIF38), a section with the highest homology to PC2. Using a Xenopus oocyte Ca(2+) imaging system, we observed that expression of QIF38 significantly reduced the initial amplitude of IP(3)-induced Ca(2+) transients, whereas a mutation lacking the C-terminal tail did not. Thus, the C terminus is essential to QIF38 function. Co-immunoprecipitation assays demonstrated that through its C terminus, QIF38 associates with the IP(3)-binding domain of IP(3)R. A shorter PC1 fragment spanning only the last TM and the C-terminal tail also reduced IP(3)-induced Ca(2+) release, whereas another C-terminal fragment lacking any TM domain did not. Thus, only endoplasmic reticulum-localized PC1 can modulate IP(3)R. Finally, we show that in the polarized Madin-Darby canine kidney cells, heterologous expression of full-length PC1 resulted in a smaller IP(3)-induced Ca(2+) response. Overexpression of the IP(3)-binding domain of IP(3)R reversed the inhibitory effect of PC1, suggesting interaction of full-length PC1 (or its cleavage forms) with endogenous IP(3)R in Madin-Darby canine kidney cells. These results indicate that the behavior of full-length PC1 in mammalian cells is congruent with that of PC1 C-terminal fragments in the oocyte system. These data demonstrate that PC1 inhibits Ca(2+) release, perhaps opposing the effect of PC2, which facilitates Ca(2+) release through the IP(3)R.
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Affiliation(s)
- Yun Li
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Netty G Santoso
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Shengqiang Yu
- Division of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Owen M Woodward
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Feng Qian
- Division of Nephrology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - William B Guggino
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
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12
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Aguiari G, Varani K, Bogo M, Mangolini A, Vincenzi F, Durante C, Gessi S, Sacchetto V, Catizone L, Harris P, Rizzuto R, Borea PA, Del Senno L. Deficiency of polycystic kidney disease-1 gene (PKD1) expression increases A(3) adenosine receptors in human renal cells: implications for cAMP-dependent signalling and proliferation of PKD1-mutated cystic cells. Biochim Biophys Acta Mol Basis Dis 2009; 1792:531-40. [PMID: 19285554 DOI: 10.1016/j.bbadis.2009.03.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 02/27/2009] [Accepted: 03/03/2009] [Indexed: 11/28/2022]
Abstract
Cyst growth and expansion in autosomal dominant polycystic kidney disease (ADPKD) has been attributed to numerous factors, including ATP, cAMP and adenosine signalling. Although the role of ATP and cAMP has been widely investigated in PKD1-deficient cells, no information is currently available on adenosine-mediated signalling. Here we investigate for the first time the impact of abnormalities of polycystin-1 (PC1) on the expression and functional activity of adenosine receptors, members of the G-protein-coupled receptor superfamily. Pharmacological, molecular and biochemical findings show that a siRNA-dependent PC1-depletion in HEK293 cells and a PKD1-nonsense mutation in cyst-derived cell lines result in increased expression of the A(3) adenosine receptor via an NFkB-dependent mechanism. Interestingly, A(3) adenosine receptor levels result higher in ADPKD than in normal renal tissues. Furthermore, the stimulation of this receptor subtype with the selective agonist Cl-IB-MECA causes a reduction in both cytosolic cAMP and cell proliferation in both PC1-deficient HEK293 cells and cystic cells. This reduction is associated with increased expression of p21(waf) and reduced activation not only of ERK1/2, but also of S6 kinase, the main target of mTOR signalling. In the light of these findings, the ability of Cl-IB-MECA to reduce disease progression in ADPKD should be further investigated. Moreover, our results suggest that NFkB, which is markedly activated in PC1-deficient and cystic cells, plays an important role in modulating A(3)AR expression in cystic cells.
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Affiliation(s)
- Gianluca Aguiari
- Department of Biochemistry and Molecular Biology, Section of Molecular Biology, University of Ferrara, Italy
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13
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Aguiari G, Trimi V, Bogo M, Mangolini A, Szabadkai G, Pinton P, Witzgall R, Harris PC, Borea PA, Rizzuto R, del Senno L. Novel role for polycystin-1 in modulating cell proliferation through calcium oscillations in kidney cells. Cell Prolif 2008; 41:554-73. [PMID: 18422703 PMCID: PMC2440503 DOI: 10.1111/j.1365-2184.2008.00529.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVES Polycystin-1 (PC1), a signalling receptor regulating Ca(2+)-permeable cation channels, is mutated in autosomal dominant polycystic kidney disease, which is typically characterized by increased cell proliferation. However, the precise mechanisms by which PC1 functions on Ca(2+) homeostasis, signalling and cell proliferation remain unclear. Here, we investigated the possible role of PC1 as a modulator of non-capacitative Ca(2+) entry (NCCE) and Ca(2+) oscillations, with downstream effects on cell proliferation. RESULTS AND DISCUSSION By employing RNA interference, we show that depletion of endogenous PC1 in HEK293 cells leads to an increase in serum-induced Ca(2+) oscillations, triggering nuclear factor of activated T cell activation and leading to cell cycle progression. Consistently, Ca(2+) oscillations and cell proliferation are increased in PC1-mutated kidney cystic cell lines, but both abnormal features are reduced in cells that exogenously express PC1. Notably, blockers of the NCCE pathway, but not of the CCE, blunt abnormal oscillation and cell proliferation. Our study therefore provides the first demonstration that PC1 modulates Ca(2+) oscillations and a molecular mechanism to explain the association between abnormal Ca(2+) homeostasis and cell proliferation in autosomal dominant polycystic kidney disease.
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Affiliation(s)
- G Aguiari
- Department of Biochemistry and Molecular Biology, University of Ferrara, Ferrara, Italy
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14
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Aguiari G, Trimi V, Bogo M, Mangolini A, Szabadkai G, Pinton P, Witzgall R, Harris PC, Borea PA, Rizzuto R, del Senno L. Novel role for polycystin-1 in modulating cell proliferation through calcium oscillations in kidney cells. Cell Prolif 2008. [PMID: 18422703 DOI: 10.1111/j.1365-2184.2008.00529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVES Polycystin-1 (PC1), a signalling receptor regulating Ca(2+)-permeable cation channels, is mutated in autosomal dominant polycystic kidney disease, which is typically characterized by increased cell proliferation. However, the precise mechanisms by which PC1 functions on Ca(2+) homeostasis, signalling and cell proliferation remain unclear. Here, we investigated the possible role of PC1 as a modulator of non-capacitative Ca(2+) entry (NCCE) and Ca(2+) oscillations, with downstream effects on cell proliferation. RESULTS AND DISCUSSION By employing RNA interference, we show that depletion of endogenous PC1 in HEK293 cells leads to an increase in serum-induced Ca(2+) oscillations, triggering nuclear factor of activated T cell activation and leading to cell cycle progression. Consistently, Ca(2+) oscillations and cell proliferation are increased in PC1-mutated kidney cystic cell lines, but both abnormal features are reduced in cells that exogenously express PC1. Notably, blockers of the NCCE pathway, but not of the CCE, blunt abnormal oscillation and cell proliferation. Our study therefore provides the first demonstration that PC1 modulates Ca(2+) oscillations and a molecular mechanism to explain the association between abnormal Ca(2+) homeostasis and cell proliferation in autosomal dominant polycystic kidney disease.
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Affiliation(s)
- G Aguiari
- Department of Biochemistry and Molecular Biology, University of Ferrara, Ferrara, Italy
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15
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Abstract
Cilia are endowed with membrane receptors, channels, and signaling components whose localization and function must be tightly controlled. In primary cilia of mammalian kidney epithelia and sensory cilia of Caenorhabditis elegans neurons, polycystin-1 (PC1) and transient receptor polycystin-2 channel (TRPP2 or PC2), function together as a mechanosensory receptor-channel complex. Despite the importance of the polycystins in sensory transduction, the mechanisms that regulate polycystin activity and localization, or ciliary membrane receptors in general, remain poorly understood. We demonstrate that signal transduction adaptor molecule STAM-1A interacts with C. elegans LOV-1 (PC1), and that STAM functions with hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) on early endosomes to direct the LOV-1-PKD-2 complex for lysosomal degradation. In a stam-1 mutant, both LOV-1 and PKD-2 improperly accumulate at the ciliary base. Conversely, overexpression of STAM or Hrs promotes the removal of PKD-2 from cilia, culminating in sensory behavioral defects. These data reveal that the STAM-Hrs complex, which down-regulates ligand-activated growth factor receptors from the cell surface of yeast and mammalian cells, also regulates the localization and signaling of a ciliary PC1 receptor-TRPP2 complex.
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Affiliation(s)
- Jinghua Hu
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin, Madison, WI 53705, USA
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16
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Torres VE, Harris PC. Mechanisms of Disease: autosomal dominant and recessive polycystic kidney diseases. ACTA ACUST UNITED AC 2006; 2:40-55; quiz 55. [PMID: 16932388 DOI: 10.1038/ncpneph0070] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Accepted: 09/27/2005] [Indexed: 12/21/2022]
Abstract
Autosomal dominant polycystic kidney disease and autosomal recessive polycystic kidney disease are the best known of a large family of inherited diseases characterized by the development of renal cysts of tubular epithelial cell origin. Autosomal dominant and recessive polycystic kidney diseases have overlapping but distinct pathogeneses. Identification of the causative mutated genes and elucidation of the function of their encoded proteins is shedding new light on the mechanisms that underlie tubular epithelial cell differentiation. This review summarizes recent literature on the role of primary cilia, intracellular calcium homeostasis, and signaling involving Wnt, cyclic AMP and Ras/MAPK, in the pathogenesis of polycystic kidney disease. Improved understanding of pathogenesis and the availability of animal models orthologous to the human diseases provide an excellent opportunity for the development of pathophysiology-based therapies. Some of these have proven effective in preclinical studies, and clinical trials have begun.
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Affiliation(s)
- Vicente E Torres
- Mayo Clinic College of Medicine, Eisenberg S33B, Nephrology, 200 First St SW, Rochester, MN 55905, USA.
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17
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Banzi M, Aguiari G, Trimi V, Mangolini A, Pinton P, Witzgall R, Rizzuto R, del Senno L. Polycystin-1 promotes PKCalpha-mediated NF-kappaB activation in kidney cells. Biochem Biophys Res Commun 2006; 350:257-62. [PMID: 17007817 DOI: 10.1016/j.bbrc.2006.09.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Accepted: 09/06/2006] [Indexed: 01/03/2023]
Abstract
Polycystin-1 (PC1), the PKD1 gene product, is a membrane receptor which regulates many cell functions, including cell proliferation and apoptosis, both typically increased in cyst lining cells in autosomal dominant polycystic kidney disease. Here we show that PC1 upregulates the NF-kappaB signalling pathway in kidney cells to prevent cell death. Human embryonic kidney cell lines (HEK293(CTT)), stably expressing a PC1 cytoplasmic terminal tail (CTT), presented increased NF-kappaB nuclear levels and NF-kappaB-mediated luciferase promoter activity. This, consistently, was reduced in HEK293 cells in which the endogenous PC1 was depleted by RNA interference. CTT-dependent NF-kappaB promoter activation was mediated by PKCalpha because it was blocked by its specific inhibitor Ro-320432. Furthermore, it was observed that apoptosis, which was increased in PC1-depleted cells, was reduced in HEK293(CTT) cells and in porcine kidney LtTA cells expressing a doxycycline-regulated CTT. Staurosporine, a PKC inhibitor, and parthenolide, a NF-kappaB inhibitor, significantly reduced the CTT-dependent antiapoptotic effect. These data reveal, therefore, a novel pathway by which polycystin-1 activates a PKCalpha-mediated NF-kappaB signalling and cell survival.
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Affiliation(s)
- Manuela Banzi
- Department of Biochemistry and Molecular Biology, University of Ferrara, Ferrara, Italy
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18
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Pelucchi B, Aguiari G, Pignatelli A, Manzati E, Witzgall R, Del Senno L, Belluzzi O. Nonspecific cation current associated with native polycystin-2 in HEK-293 cells. J Am Soc Nephrol 2006; 17:388-97. [PMID: 16396967 DOI: 10.1681/asn.2004121146] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mutations in either PKD1 or PKD2 gene are associated with autosomal dominant polycystic kidney disease, the most common inherited kidney disorder. Polycystin-2 (PC2), the PKD2 gene product, and the related protein polycystin-L, function as Ca(2+)-permeable, nonselective cation channels in different expression systems. This work describes a nonspecific cation current (I(CC)) that is present in native HEK-293 cells and highly associated with a PC2-channel activity. The current is voltage dependent, activating for potentials that are positive to -50 mV and inactivating in a few milliseconds. It is sensitive to Cd(2+), Gd(3+), La(3+), SKF96365, and amiloride. After silencing of PC2 by RNA interfering, cells show a reduced current that is restored by transfection with normal but not truncated PC2. Consistently, I(CC) is abolished by perfusion with an anti-PC2 antibody. Furthermore, heterologous expression of the PC1 cytoplasmic tail significantly increases I(CC) peak amplitude compared with native cells. This is the first characterization of such a current in HEK-293 cells, a widely used expression system for ion channels. These cells, therefore, could be regarded as a suitable and readily accessible tool to study interactions between native PC2/PC1 complex and other membrane proteins, thus contributing to the understanding of autosomal dominant polycystic kidney disease pathogenesis.
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Affiliation(s)
- Bruna Pelucchi
- Department of Biology, University of Ferrara, Via L. Borsari 46, Ferrara I-44100, Italy.
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19
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Chernova MN, Vandorpe DH, Clark JS, Alper SL. Expression of the polycystin-1 C-terminal cytoplasmic tail increases Cl channel activity in Xenopus oocytes. Kidney Int 2005; 68:632-41. [PMID: 16014040 DOI: 10.1111/j.1523-1755.2005.00441.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Expression of the polycystin-1 C-terminal cytoplasmic tail increases Cl(-) channel activity in Xenopus oocytes. Background. Cyst expansion in autosomal-dominant polycystic kidney disease (ADPKD) is characterized by active Cl(-) secretion in excess of solute reabsorption. However, the connections between elevated epithelial Cl(-) secretion and loss-of-function or dysregulation of either ADPKD gene polycystin-1 (PC1) or polycystin-2 (PC2) remain little understood. Methods. Cl(-) transport in Xenopus oocytes expressing the CD16.7-PKD1 (115-226) fusion protein containing the final 112 amino acid (aa) of the PC1 C-terminal cytoplasmic tail, or in oocytes expressing related PC1 fusion protein mutants, was studied by isotopic flux, two-electrode voltage clamp, and outside-out patch clamp recording. Results. Expression in oocytes of CD16.7-PKD1 (115-226) increased rates of both influx and efflux of (36)Cl(-), whereas CD16.7-PKD1 (1-92) containing the initial 92 aa of the PC1 C-terminal cytoplasmic tail was inactive. The increased Cl(-) transport resembled CD16.7-PKD1 (115-226)-stimulated cation current in its sensitivity to ADPKD-associated missense mutations, to mutations in phosphorylation sites, and to mutations within or encroaching upon the PC1 coiled-coil domain, as well as in its partial suppression by coexpressed PC2. The NS3623- and 4, 4'-diisothiocyanatostilbene-2, 2'-disulfonic acid (DIDS)-sensitive (36)Cl(-) flux was not blocked by injected ethyleneglycol tetraacetate (EGTA) or by the cation channel inhibitor SKF96365, and was stimulated by the cation channel inhibitor La(3+), suggesting that CD16.7-PKD1 (115-226)-associated cation conductance was not required for (36)CI(-) flux activation. Outside-out patches from oocytes expressing CD16.7-PKD1 (115-226) also exhibited increased NS3623-sensitive Cl(-) current. Conclusion. These data show that CD16.7-PKD1 (115-226) activates Cl(-) channels in the Xenopus oocyte plasma membrane in parallel with, but not secondary to, activation of Ca(2+)-permeable cation channels.
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Affiliation(s)
- Marina N Chernova
- Molecular and Vascular Medicine Unit and Renal Division, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
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20
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Hooper KM, Boletta A, Germino GG, Hu Q, Ziegelstein RC, Sutters M. Expression of polycystin-1 enhances endoplasmic reticulum calcium uptake and decreases capacitative calcium entry in ATP-stimulated MDCK cells. Am J Physiol Renal Physiol 2005; 289:F521-30. [PMID: 15870383 DOI: 10.1152/ajprenal.00355.2004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) types 1 and 2 arise as a consequence of mutations in the PKD1 or PKD2 genes, encoding polycystins-1 and -2. Because loss of function of either of the polycystins leads to a very similar phenotype and the two proteins are known to interact, polycystins-1 and -2 are probably active in the same pathway. The way in which loss of either polycystin leads to the development of ADPKD remains to be established, but disturbances of cell calcium regulation are likely to play an important role. Here, we demonstrate that polycystin-1, heterologously expressed in Madin-Darby canine kidney cells, had a pronounced effect on intracellular calcium homeostasis. ATP-induced calcium responses in transfection control cells exhibited a double peak and relatively gradual return to baseline. By contrast, cells expressing heterologous polycystin-1 showed a brief, uniphasic peak and an accelerated rate of decay. Heterologously expressed polycystin-1 accelerated endoplasmic reticulum (ER) calcium reuptake and inhibited capacitative calcium entry; we found no effect of the protein on mitochondrial calcium buffering or plasma membrane calcium extrusion. We therefore propose that polycystin-1 accelerated the decay of the cell calcium response to ATP by upregulation of ER calcium reuptake and consequent minimization of the stimulus for capacitative calcium entry. It is possible that cellular dedifferentiation, fluid secretion, and proliferation might therefore arise in ADPKD as a consequence of disturbances in cytoplasmic and ER calcium homeostasis and aberrant capacitative calcium entry.
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Affiliation(s)
- K M Hooper
- Div. of Renal Medicine, Johns Hopkins Bayview Medical Ctr., 4940 Eastern Ave., Baltimore, MD 21224, USA
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21
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Wang Y, Shibasaki F, Mizuno K. Calcium signal-induced cofilin dephosphorylation is mediated by Slingshot via calcineurin. J Biol Chem 2005; 280:12683-9. [PMID: 15671020 DOI: 10.1074/jbc.m411494200] [Citation(s) in RCA: 180] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cofilin, an essential regulator of actin filament dynamics, is inactivated by phosphorylation at Ser-3 and reactivated by dephosphorylation. Although cofilin undergoes dephosphorylation in response to extracellular stimuli that elevate intracellular Ca2+ concentrations, signaling mechanisms mediating Ca2+-induced cofilin dephosphorylation have remained unknown. We investigated the role of Slingshot (SSH) 1L, a member of a SSH family of protein phosphatases, in mediating Ca2+-induced cofilin dephosphorylation. The Ca2+ ionophore A23187 and Ca2+-mobilizing agonists, ATP and histamine, induced SSH1L activation and cofilin dephosphorylation in cultured cells. A23187- or histamine-induced SSH1L activation and cofilin dephosphorylation were blocked by calcineurin inhibitors or a dominant-negative form of calcineurin, indicating that calcineurin mediates Ca2+-induced SSH1L activation and cofilin dephosphorylation. Importantly, knockdown of SSH1L expression by RNA interference abolished A23187- or calcineurin-induced cofilin dephosphorylation. Furthermore, calcineurin dephosphorylated SSH1L and increased the cofilin-phosphatase activity of SSH1L in cell-free assays. Based on these findings, we suggest that Ca2+-induced cofilin dephosphorylation is mediated by calcineurin-dependent activation of SSH1L.
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Affiliation(s)
- Yan Wang
- Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
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22
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Abstract
Autosomal dominant PKD (ADPKD) is a common lethal genetic disorder characterized by progressive development of fluid-filled cysts in the kidney and other target organs. ADPKD is caused by mutations in the PKD1 and PKD2 genes, encoding the transmembrane proteins polycystin-1 (PC1) and polycystin-2 (PC2), respectively. Although the function and putative interacting ligands of PC1 are largely unknown, recent evidence indicates that PC2 behaves as a TRP-type Ca2+-permeable nonselective cation channel. The PC2 channel is implicated in the transient increase in cytosolic Ca2+in renal epithelial cells and may be linked to the activation of subsequent signaling pathways. Recent studies also indicate that PC1 functionally interacts with PC2 such that the PC1-PC2 channel complex is an obligatory novel signaling pathway implicated in the transduction of environmental signals into cellular events. The present review purposely avoids issues of regulation of PC2 expression and trafficking and focuses instead on the evidence for the TRP-type cation channel function of PC2. How its role as a cation channel may unmask mechanisms that trigger Ca2+transport and regulation is the focus of attention. PC2 channel function may be essential in renal cell function and kidney development. Nonrenal-targeted expression of PC2 and related proteins, including the cardiovascular system, also suggests previously unforeseeable roles in signal transduction.
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Affiliation(s)
- Horacio F Cantiello
- Renal Unit, Massachusetts General Hospital East, 149 13th St., Charlestown, MA 02129, USA.
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23
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Aguiari G, Banzi M, Gessi S, Cai Y, Zeggio E, Manzati E, Piva R, Lambertini E, Ferrari L, Peters DJ, Lanza F, Harris PC, Borea PA, Somlo S, Del Senno L. Deficiency of polycystin‐2 reduces Ca2+channel activity and cell proliferation in ADPKD lymphoblastoid cells. FASEB J 2004; 18:884-6. [PMID: 15001556 DOI: 10.1096/fj.03-0687fje] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Polycystin-2 (PC2), encoded by the PKD2 gene, mutated in 10-15% of autosomal-dominant polycystic kidney disease (ADPKD) patients, is a Ca2+-permeable cation channel present in kidney epithelia and other tissues. As PC2 was found expressed in B-lymphoblastoid cells (LCLs) and Ca2+ signaling pathways are important regulators of B cell function activities, we investigated whether PC2 plays some role in B-LCLs. In LCLs, PC2 was found mainly in ER membranes but ~8 times less than in kidney HEK293 cells. The same reductions were found in PKD2 and PKD1 RNA; thus, PKD genes maintained, in LCLs, the same reciprocal proportion as they do in kidney cells. In LCLs obtained from subjects carrying PKD2 mutations (PKD2-LCLs) and showing reduced PC2 levels, intracellular Ca2+ concentrations evoked by platelet-activating factor (PAF), were significantly lower than in non-PKD-LCLs. This reduction was also found in PKD1-LCLs but without PC2 reductions. Likewise, cell proliferation, which is controlled by Ca2+, was reduced in PKD2- and PKD1-LCLs. Moreover, in LCLs with PKD2 nonsense mutations, aminoglycoside antibiotics reduced the PC2 defect by promoting readthrough of stop codons. Therefore, PC2 and PC1 are functionally expressed in LCLs, which provide a model, easily obtainable from ADPKD patients, to study PKD gene expression and function.
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Affiliation(s)
- Gianluca Aguiari
- Department of Biochemistry and Molecular Biology, University of Ferrara, Ferrara, Italy
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24
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Wildman SS, Hooper KM, Turner CM, Sham JSK, Lakatta EG, King BF, Unwin RJ, Sutters M. The isolated polycystin-1 cytoplasmic COOH terminus prolongs ATP-stimulated Cl- conductance through increased Ca2+ entry. Am J Physiol Renal Physiol 2003; 285:F1168-78. [PMID: 12888616 DOI: 10.1152/ajprenal.00171.2003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The precise steps leading from mutation of the polycystic kidney disease (PKD1) gene to the autosomal dominant polycystic kidney disease (ADPKD) phenotype remain to be established. Fluid accumulation is a requirement for cyst expansion in ADPKD, suggesting that abnormal fluid secretion into the cyst lumen might play a role in disease. In this study, we sought to establish a link between polycystin-1 (the PKD1 gene product) and ATP-stimulated Cl- secretion in renal tubule cells. To do this, we performed a whole cell patch-clamp analysis of the effects of expression of the isolated cytoplasmic COOH-terminus of polycystin-1 in stably transfected mouse cortical collecting duct cells. The truncated polycystin-1 fusion protein prolonged the duration of ATP-stimulated Cl- conductance and intracellular Ca2+ responses. Both effects were dependent on extracellular Ca2+. It was determined that expression of the truncated polycystin-1 fusion protein introduced, or activated, an ATP-induced Ca2+ entry pathway that was undetectable in transfection control cell lines. Our findings are concordant with increasing evidence for a role of polycystin-1 in cell Ca2+ homeostasis and indicate that dysregulated Ca2+ entry might promote Cl- secretion and cyst expansion in ADPKD.
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Affiliation(s)
- Scott S Wildman
- Laboratory of Cardiological Sciences, Gerontology Research Center, Division of Renal Medicine, Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, Baltimore, MD 21224, USA
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