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Chen PL, Chen CF, Lin HYH, Riley DJ, Chen Y. The Link between Autosomal Dominant Polycystic Kidney Disease and Chromosomal Instability: Exploring the Relationship. Int J Mol Sci 2024; 25:2936. [PMID: 38474184 PMCID: PMC10932443 DOI: 10.3390/ijms25052936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/27/2024] [Accepted: 03/01/2024] [Indexed: 03/14/2024] Open
Abstract
In autosomal dominant polycystic kidney disease (ADPKD) with germline mutations in a PKD1 or PKD2 gene, innumerable cysts develop from tubules, and renal function deteriorates. Second-hit somatic mutations and renal tubular epithelial (RTE) cell death are crucial features of cyst initiation and disease progression. Here, we use established RTE lines and primary ADPKD cells with disease-associated PKD1 mutations to investigate genomic instability and DNA damage responses. We found that ADPKD cells suffer severe chromosome breakage, aneuploidy, heightened susceptibility to DNA damage, and delayed checkpoint activation. Immunohistochemical analyses of human kidneys corroborated observations in cultured cells. DNA damage sensors (ATM/ATR) were activated but did not localize at nuclear sites of damaged DNA and did not properly activate downstream transducers (CHK1/CHK2). ADPKD cells also had the ability to transform, as they achieved high saturation density and formed colonies in soft agar. Our studies indicate that defective DNA damage repair pathways and the somatic mutagenesis they cause contribute fundamentally to the pathogenesis of ADPKD. Acquired mutations may alternatively confer proliferative advantages to the clonally expanded cell populations or lead to apoptosis. Further understanding of the molecular details of aberrant DNA damage responses in ADPKD is ongoing and holds promise for targeted therapies.
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Affiliation(s)
- Phang-Lang Chen
- Department of Biological Chemistry, University of California, Irvine, CA 92697, USA; (P.-L.C.); (C.-F.C.)
| | - Chi-Fen Chen
- Department of Biological Chemistry, University of California, Irvine, CA 92697, USA; (P.-L.C.); (C.-F.C.)
| | - Hugo Y.-H. Lin
- Division of Nephrology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan;
- Internal Medicine, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University, Kaohsiung 807, Taiwan
- Department of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Daniel J. Riley
- Department of Medicine, Division of Nephrology, University of Texas Health, San Antonio, TX 78245, USA;
| | - Yumay Chen
- Department of Medicine, Division of Endocrinology, University of California, Irvine, CA 92697, USA
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2
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Yasinoglu SA, Kuipers TB, Suidgeest E, van der Weerd L, Mei H, Baelde HJ, Peters DJM. Transcriptomic profiling of Polycystic Kidney Disease identifies paracrine factors in the early cyst microenvironment. Biochim Biophys Acta Mol Basis Dis 2024; 1870:166987. [PMID: 38070582 DOI: 10.1016/j.bbadis.2023.166987] [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: 08/23/2023] [Revised: 11/30/2023] [Accepted: 12/04/2023] [Indexed: 12/21/2023]
Abstract
Initial cysts that are formed upon Pkd1 loss in mice impose persistent stress on surrounding tissue and trigger a cystic snowball effect, in which local aberrant PKD-related signaling increases the likelihood of new cyst formation, ultimately leading to accelerated disease progression. Although many pathways have been associated with PKD progression, the knowledge of early changes near initial cysts is limited. To perform an unbiased analysis of transcriptomic alterations in the cyst microenvironment, microdomains were collected from kidney sections of iKsp-Pkd1del mice with scattered Pkd1-deletion using Laser Capture Microdissection. These microdomains were defined as F4/80-low cystic, representing early alterations in the cyst microenvironment, F4/80-high cystic, with more advanced alterations, or non-cystic. RNA sequencing and differential gene expression analysis revealed 953 and 8088 dysregulated genes in the F4/80-low and F4/80-high cyst microenvironment, respectively, when compared to non-cystic microdomains. In the early cyst microenvironment, several injury-repair, growth, and tissue remodeling-related pathways were activated, accompanied by mild metabolic changes. In the more advanced F4/80-high microdomains, these pathways were potentiated and the metabolism was highly dysregulated. Upstream regulator analysis revealed a series of paracrine factors with increased activity in the early cyst microenvironment, including TNFSF12 and OSM. In line with the upstream regulator analysis, TWEAK and Oncostatin-M promoted cell proliferation and inflammatory gene expression in renal epithelial cells and fibroblasts in vitro. Collectively, our data provide an overview of molecular alterations that specifically occur in the cyst microenvironment and identify paracrine factors that may mediate early and advanced alterations in the cyst microenvironment.
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Affiliation(s)
- Sevtap A Yasinoglu
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Thomas B Kuipers
- Sequencing Analysis Support Core, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, the Netherlands
| | - Ernst Suidgeest
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Louise van der Weerd
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Hailiang Mei
- Sequencing Analysis Support Core, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, the Netherlands
| | - Hans J Baelde
- Department of Pathology, Leiden University Medical Center, Leiden, the Netherlands
| | - Dorien J M Peters
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands.
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3
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Kumar P, Zadjali F, Yao Y, Köttgen M, Hofherr A, Gross KW, Mehta D, Bissler JJ. Single Gene Mutations in Pkd1 or Tsc2 Alter Extracellular Vesicle Production and Trafficking. BIOLOGY 2022; 11:biology11050709. [PMID: 35625437 PMCID: PMC9139108 DOI: 10.3390/biology11050709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/20/2022] [Accepted: 04/30/2022] [Indexed: 12/17/2022]
Abstract
Simple Summary Extracellular vesicles shed from primary cilia may be involved in renal cystogenesis. The disruption of the Pkd1 gene in our cell culture system increased the production of EVs in a similar way that occurs when the Tsc2 gene is disrupted. Disruption of the primary cilia depresses EV production, and this may be the reason that the combined Kif3A/Pkd1 mutant mouse has a less severe phenotype than the Pkd1 mutant alone. We initiated studies aimed at understanding the renal trafficking of renally-derived EVs and found that single gene disruptions can alter the EV kinetics based on dye tracking studies. These results raise the possibility that EV features, such as cargo, dose, tissue half-life, and targeting, may be involved in the disease process, and these features may also be fertile targets for diagnostic, prognostic, and therapeutic investigation. Abstract Patients with autosomal dominant polycystic kidney disease (ADPKD) and tuberous sclerosis complex (TSC) are born with normal or near-normal kidneys that later develop cysts and prematurely lose function. Both renal cystic diseases appear to be mediated, at least in part, by disease-promoting extracellular vesicles (EVs) that induce genetically intact cells to participate in the renal disease process. We used centrifugation and size exclusion chromatography to isolate the EVs for study. We characterized the EVs using tunable resistive pulse sensing, dynamic light scattering, transmission electron microscopy, and Western blot analysis. We performed EV trafficking studies using a dye approach in both tissue culture and in vivo studies. We have previously reported that loss of the Tsc2 gene significantly increased EV production and here demonstrate that the loss of the Pkd1 gene also significantly increases EV production. Using a cell culture system, we also show that loss of either the Tsc2 or Pkd1 gene results in EVs that exhibit an enhanced uptake by renal epithelial cells and a prolonged half-life. Loss of the primary cilia significantly reduces EV production in renal collecting duct cells. Cells that have a disrupted Pkd1 gene produce EVs that have altered kinetics and a prolonged half-life, possibly impacting the duration of the EV cargo effect on the recipient cell. These results demonstrate the interplay between primary cilia and EVs and support a role for EVs in polycystic kidney disease pathogenesis.
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Affiliation(s)
- Prashant Kumar
- Department of Pediatrics, Le Bonheur Children’s Hospital, University of Tennessee Health Science Center, Memphis, TN 38103, USA; (P.K.); (F.Z.); (Y.Y.)
- Children’s Foundation Research Institute (CFRI), Le Bonheur Children’s Hospital, Memphis, TN 38103, USA
- US FDA National Center for Toxicological Research, Jefferson, AR 72079, USA;
| | - Fahad Zadjali
- Department of Pediatrics, Le Bonheur Children’s Hospital, University of Tennessee Health Science Center, Memphis, TN 38103, USA; (P.K.); (F.Z.); (Y.Y.)
- Children’s Foundation Research Institute (CFRI), Le Bonheur Children’s Hospital, Memphis, TN 38103, USA
- Department of Clinical Biochemistry, College of Medicine & Health Sciences, Sultan Qaboos University, Muscat 123, Oman
| | - Ying Yao
- Department of Pediatrics, Le Bonheur Children’s Hospital, University of Tennessee Health Science Center, Memphis, TN 38103, USA; (P.K.); (F.Z.); (Y.Y.)
- Children’s Foundation Research Institute (CFRI), Le Bonheur Children’s Hospital, Memphis, TN 38103, USA
| | - Michael Köttgen
- Renal Division, Department of Medicine, Medical Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany; (M.K.); (A.H.)
- CIBSS—Centre for Integrative Biological Signaling Studies, 79104 Freiburg, Germany
| | - Alexis Hofherr
- Renal Division, Department of Medicine, Medical Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany; (M.K.); (A.H.)
| | - Kenneth W. Gross
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA;
| | - Darshan Mehta
- US FDA National Center for Toxicological Research, Jefferson, AR 72079, USA;
| | - John J. Bissler
- Department of Pediatrics, Le Bonheur Children’s Hospital, University of Tennessee Health Science Center, Memphis, TN 38103, USA; (P.K.); (F.Z.); (Y.Y.)
- Children’s Foundation Research Institute (CFRI), Le Bonheur Children’s Hospital, Memphis, TN 38103, USA
- Pediatric Medicine Department, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
- Correspondence:
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4
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Bowden SA, Rodger EJ, Chatterjee A, Eccles MR, Stayner C. Recent Discoveries in Epigenetic Modifications of Polycystic Kidney Disease. Int J Mol Sci 2021; 22:ijms222413327. [PMID: 34948126 PMCID: PMC8708269 DOI: 10.3390/ijms222413327] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 12/01/2021] [Accepted: 12/07/2021] [Indexed: 01/01/2023] Open
Abstract
Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a heritable renal disease that results in end-stage kidney disease, due to the uncontrolled bilateral growth of cysts throughout the kidneys. While it is known that a mutation within a PKD-causing gene is required for the development of ADPKD, the underlying mechanism(s) causing cystogenesis and progression of the disease are not well understood. Limited therapeutic options are currently available to slow the rate of cystic growth. Epigenetic modifications, including DNA methylation, are known to be altered in neoplasia, and several FDA-approved therapeutics target these disease-specific changes. As there are many similarities between ADPKD and neoplasia, we (and others) have postulated that ADPKD kidneys contain alterations to their epigenetic landscape that could be exploited for future therapeutic discovery. Here we summarise the current understanding of epigenetic changes that are associated with ADPKD, with a particular focus on the burgeoning field of ADPKD-specific alterations in DNA methylation.
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Affiliation(s)
- Sarah A. Bowden
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin 9054, New Zealand; (S.A.B.); (E.J.R.); (A.C.); (M.R.E.)
| | - Euan J. Rodger
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin 9054, New Zealand; (S.A.B.); (E.J.R.); (A.C.); (M.R.E.)
- Maurice Wilkins Centre for Molecular Biodiscovery, Level 2, 3A Symonds Street, Auckland 1010, New Zealand
| | - Aniruddha Chatterjee
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin 9054, New Zealand; (S.A.B.); (E.J.R.); (A.C.); (M.R.E.)
- Maurice Wilkins Centre for Molecular Biodiscovery, Level 2, 3A Symonds Street, Auckland 1010, New Zealand
| | - Michael R. Eccles
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin 9054, New Zealand; (S.A.B.); (E.J.R.); (A.C.); (M.R.E.)
- Maurice Wilkins Centre for Molecular Biodiscovery, Level 2, 3A Symonds Street, Auckland 1010, New Zealand
| | - Cherie Stayner
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin 9054, New Zealand; (S.A.B.); (E.J.R.); (A.C.); (M.R.E.)
- Correspondence: ; Tel.: +64-3-479-5060; Fax: +64-3-479-7136
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5
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Groopman EE, Povysil G, Goldstein DB, Gharavi AG. Rare genetic causes of complex kidney and urological diseases. Nat Rev Nephrol 2020; 16:641-656. [PMID: 32807983 PMCID: PMC7772719 DOI: 10.1038/s41581-020-0325-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2020] [Indexed: 02/08/2023]
Abstract
Although often considered a single-entity, chronic kidney disease (CKD) comprises many pathophysiologically distinct disorders that result in persistently abnormal kidney structure and/or function, and encompass both monogenic and polygenic aetiologies. Rare inherited forms of CKD frequently span diverse phenotypes, reflecting genetic phenomena including pleiotropy, incomplete penetrance and variable expressivity. Use of chromosomal microarray and massively parallel sequencing technologies has revealed that genomic disorders and monogenic aetiologies contribute meaningfully to seemingly complex forms of CKD across different clinically defined subgroups and are characterized by high genetic and phenotypic heterogeneity. Investigations of prevalent genomic disorders in CKD have integrated genetic, bioinformatic and functional studies to pinpoint the genetic drivers underlying their renal and extra-renal manifestations, revealing both monogenic and polygenic mechanisms. Similarly, massively parallel sequencing-based analyses have identified gene- and allele-level variation that contribute to the clinically diverse phenotypes observed for many monogenic forms of nephropathy. Genome-wide sequencing studies suggest that dual genetic diagnoses are found in at least 5% of patients in whom a genetic cause of disease is identified, highlighting the fact that complex phenotypes can also arise from multilocus variation. A multifaceted approach that incorporates genetic and phenotypic data from large, diverse cohorts will help to elucidate the complex relationships between genotype and phenotype for different forms of CKD, supporting personalized medicine for individuals with kidney disease.
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Affiliation(s)
- Emily E Groopman
- Division of Nephrology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Gundula Povysil
- Institute for Genomic Medicine, Columbia University, New York, NY, USA
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University, New York, NY, USA
| | - Ali G Gharavi
- Division of Nephrology, Columbia University College of Physicians and Surgeons, New York, NY, USA.
- Institute for Genomic Medicine, Columbia University, New York, NY, USA.
- Center for Precision Medicine and Genomics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY, USA.
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6
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VanNoy GE, Wojcik MH, Genetti CA, Mullen TE, Agrawal PB, Stein DR. Reconsidering Genetic Testing for Neonatal Polycystic Kidney Disease. Kidney Int Rep 2020; 5:1316-1319. [PMID: 32775833 PMCID: PMC7403496 DOI: 10.1016/j.ekir.2020.05.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 01/08/2023] Open
Affiliation(s)
- Grace E VanNoy
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA.,The Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Monica H Wojcik
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA.,The Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,Divisions of Genetics and Genomics and Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Casie A Genetti
- The Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Thomas E Mullen
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Pankaj B Agrawal
- The Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,Divisions of Genetics and Genomics and Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Deborah R Stein
- Division of Nephrology, Boston Children's Hospital, Boston, Massachusetts, USA
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7
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Identification of ADPKD-Related Genes and Pathways in Cells Overexpressing PKD2. Genes (Basel) 2020; 11:genes11020122. [PMID: 31979107 PMCID: PMC7074416 DOI: 10.3390/genes11020122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/20/2020] [Accepted: 01/21/2020] [Indexed: 11/17/2022] Open
Abstract
Consistent with the gene dosage effect hypothesis, renal cysts can arise in transgenic murine models overexpressing either PKD1 or PKD2, which are causal genes for autosomal dominant polycystic kidney disease (ADPKD). To determine whether PKD gene overexpression is a universal mechanism driving cystogenesis or is merely restricted to rodents, other animal models are required. Previously, we failed to observe any renal cysts in a transgenic porcine model of PKD2 overexpression partially due to epigenetic silencing of the transgene. Thus, to explore the feasibility of porcine models and identify potential genes/pathways affected in ADPKD, LLC-PK1 cells with high PKD2 expression were generated. mRNA sequencing (RNA-seq) was performed, and MYC, IER3, and ADM were found to be upregulated genes common to the different PKD2 overexpression cell models. MYC is a well-characterized factor contributing to cystogenesis, and ADM is a biomarker for chronic kidney disease. Thus, these genes might be indicators of disease progression. Additionally, some ADPKD-associated pathways, e.g., the mitogen-activated protein kinase (MAPK) pathway, were enriched in the cells. Moreover, gene ontology (GO) analysis demonstrated that proliferation, apoptosis, and cell cycle regulation, which are hallmarks of ADPKD, were altered. Therefore, our experiment identified some biomarkers or indicators of ADPKD, indicating that high PKD2 expression would likely drive cystogenesis in future porcine models.
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8
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Stayner C, Brooke DG, Bates M, Eccles MR. Targeted Therapies for Autosomal Dominant Polycystic Kidney Disease. Curr Med Chem 2019; 26:3081-3102. [PMID: 29737248 DOI: 10.2174/0929867325666180508095654] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 02/12/2018] [Accepted: 02/12/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND Autosomal dominant polycystic kidney disease (ADPKD) is the most common life-threatening genetic disease in humans, affecting approximately 1 in 500 people. ADPKD is characterized by cyst growth in the kidney leading to progressive parenchymal damage and is the underlying pathology in approximately 10% of patients requiring hemodialysis or transplantation for end-stage kidney disease. The two proteins that are mutated in ADPKD, polycystin-1 and polycystin-2, form a complex located on the primary cilium and the plasma membrane to facilitate calcium ion release in the cell. There is currently no Food and Drug Administration (FDA)-approved therapy to cure or slow the progression of the disease. Rodent ADPKD models do not completely mimic the human disease, and therefore preclinical results have not always successfully translated to the clinic. Moreover, the toxicity of many of these potential therapies has led to patient withdrawals from clinical trials. RESULTS Here, we review compounds in clinical trial for treating ADPKD, and we examine the feasibility of using a kidney-targeted approach, with potential for broadening the therapeutic window, decreasing treatment-associated toxicity and increasing the efficacy of agents that have demonstrated activity in animal models. We make recommendations for integrating kidney- targeted therapies with current treatment regimes, to achieve a combined approach to treating ADPKD. CONCLUSION Many compounds are currently in clinical trial for ADPKD yet, to date, none are FDA-approved for treating this disease. Patients could benefit from efficacious pharmacotherapy, especially if it can be kidney-targeted, and intensive efforts continue to be focused on this goal.
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Affiliation(s)
- Cherie Stayner
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin 9054, New Zealand
| | - Darby G Brooke
- Cawthron Institute, 98 Halifax Street East, Nelson 7010, New Zealand
| | - Michael Bates
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin 9054, New Zealand
| | - Michael R Eccles
- Department of Pathology, Dunedin School of Medicine, University of Otago, 270 Great King Street, Dunedin 9054, New Zealand
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9
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Arora V, Bijarnia-Mahay S, Tiwari V, Bansal S, Gupta P, Setia N, Puri RD, Verma IC. Co-inheritance of pathogenic variants in PKD1 and PKD2 genes presenting as severe antenatal phenotype of autosomal dominant polycystic kidney disease. Eur J Med Genet 2019; 63:103734. [PMID: 31349084 DOI: 10.1016/j.ejmg.2019.103734] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 07/16/2019] [Accepted: 07/22/2019] [Indexed: 11/27/2022]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is caused by pathogenic variants in either PKD1 or PKD2 genes. Disease severity is dependent on various factors including the presence of modifier genes. We describe a family with recurrent foetal presentation of ADPKD due to co-inheritance of pathogenic variants in both PKD1 [c.3860T > C; p.(Leu1287Pro)] and PKD2 [(c.1000C > A; p.(Pro334Thr)] genes. Familial segregation studies revealed the mother and the father to be heterozygous for the same variants in the PKD1 and PKD2 genes, respectively, as found in the foetus. Renal ultrasonography detected evidence of cystic disease in the mother and two of her family members. No cysts were detected in the father, however the paternal grandfather died of renal cystic disease. The absence of disease in the father can be explained by the phenomenon of incomplete penetrance, or Knudson's two-hit hypothesis of cystogenesis in the grandfather. This case underscores the importance of sequencing PKD2 gene even in the presence of a familial PKD1 variant, as well as genetic testing of the cysts for evidence of the second hit.
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Affiliation(s)
- Veronica Arora
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
| | - Sunita Bijarnia-Mahay
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India.
| | - Vaibhav Tiwari
- Department of Nephrology, Sir Ganga Ram Hospital, New Delhi, India
| | - Savita Bansal
- Department of Obstetrics and Gynaecology and Fetal Medicine, Fortis Escorts Hospital, Jaipur, Rajasthan, India
| | - Pallav Gupta
- Department of Pathology, Sir Ganga Ram Hospital, New Delhi, India
| | - Nitika Setia
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
| | - Ratna D Puri
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
| | - Ishwar C Verma
- Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital, New Delhi, India
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10
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Miyoshi T, Hiratsuka K, Saiz EG, Morizane R. Kidney organoids in translational medicine: Disease modeling and regenerative medicine. Dev Dyn 2019; 249:34-45. [PMID: 30843293 DOI: 10.1002/dvdy.22] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 03/04/2019] [Accepted: 03/04/2019] [Indexed: 12/15/2022] Open
Abstract
The kidney is one of the most complex organs composed of multiple cell types, functioning to maintain homeostasis by means of the filtering of metabolic wastes, balancing of blood electrolytes, and adjustment of blood pressure. Recent advances in 3D culture technologies in vitro enabled the generation of "organoids" which mimic the structure and function of in vivo organs. Organoid technology has allowed for new insights into human organ development and human pathophysiology, with great potential for translational research. Increasing evidence shows that kidney organoids are a useful platform for disease modeling of genetic kidney diseases when derived from genetic patient iPSCs and/or CRISPR-mutated stem cells. Although single cell RNA-seq studies highlight the technical difficulties underlying kidney organoid generation reproducibility and variation in differentiation protocols, kidney organoids still hold great potential to understand kidney pathophysiology as applied to kidney injury and fibrosis. In this review, we summarize various studies of kidney organoids, disease modeling, genome-editing, and bioengineering, and additionally discuss the potential of and current challenges to kidney organoid research.
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Affiliation(s)
- Tomoya Miyoshi
- Renal Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts
| | - Ken Hiratsuka
- Renal Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Edgar Garcia Saiz
- Renal Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts
| | - Ryuji Morizane
- Renal Division, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.,Department of Medicine, Harvard Medical School, Boston, Massachusetts.,Harvard Stem Cell Institute, Cambridge, Massachusetts.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts
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11
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Raptis V, Loutradis C, Sarafidis PA. Renal injury progression in autosomal dominant polycystic kidney disease: a look beyond the cysts. Nephrol Dial Transplant 2018; 33:1887-1895. [DOI: 10.1093/ndt/gfy023] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
Affiliation(s)
- Vasileios Raptis
- Section of Nephrology and Hypertension, 1st Department of Medicine, AHEPA Hospital, Thessaloniki, Greece
| | - Charalampos Loutradis
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Pantelis A Sarafidis
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
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12
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Busch T, Köttgen M, Hofherr A. TRPP2 ion channels: Critical regulators of organ morphogenesis in health and disease. Cell Calcium 2017; 66:25-32. [PMID: 28807147 DOI: 10.1016/j.ceca.2017.05.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/08/2017] [Accepted: 05/08/2017] [Indexed: 12/31/2022]
Abstract
Ion channels control the membrane potential and mediate transport of ions across membranes. Archetypical physiological functions of ion channels include processes such as regulation of neuronal excitability, muscle contraction, or transepithelial ion transport. In that regard, transient receptor potential ion channel polycystin 2 (TRPP2) is remarkable, because it controls complex morphogenetic processes such as the establishment of properly shaped epithelial tubules and left-right-asymmetry of organs. The fascinating question of how an ion channel regulates morphogenesis has since captivated the attention of scientists in different disciplines. Four loosely connected key insights on different levels of biological complexity ranging from protein to whole organism have framed our understanding of TRPP2 physiology: 1) TRPP2 is a non-selective cation channel; 2) TRPP2 is part of a receptor-ion channel complex; 3) TRPP2 localizes to primary cilia; and 4) TRPP2 is required for organ morphogenesis. In this review, we will discuss the current knowledge in these key areas and highlight some of the challenges ahead.
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Affiliation(s)
- Tilman Busch
- Renal Division, Department of Medicine, Faculty of Medicine, University of Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany
| | - Michael Köttgen
- Renal Division, Department of Medicine, Faculty of Medicine, University of Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany.
| | - Alexis Hofherr
- Renal Division, Department of Medicine, Faculty of Medicine, University of Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany.
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Structure of the polycystic kidney disease TRP channel Polycystin-2 (PC2). Nat Struct Mol Biol 2016; 24:114-122. [PMID: 27991905 DOI: 10.1038/nsmb.3343] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/14/2016] [Indexed: 12/12/2022]
Abstract
Mutations in either polycystin-1 (PC1 or PKD1) or polycystin-2 (PC2, PKD2 or TRPP1) cause autosomal-dominant polycystic kidney disease (ADPKD) through unknown mechanisms. Here we present the structure of human PC2 in a closed conformation, solved by electron cryomicroscopy at 4.2-Å resolution. The structure reveals a novel polycystin-specific 'tetragonal opening for polycystins' (TOP) domain tightly bound to the top of a classic transient receptor potential (TRP) channel structure. The TOP domain is formed from two extensions to the voltage-sensor-like domain (VSLD); it covers the channel's endoplasmic reticulum lumen or extracellular surface and encloses an upper vestibule, above the pore filter, without blocking the ion-conduction pathway. The TOP-domain fold is conserved among the polycystins, including the homologous channel-like region of PC1, and is the site of a cluster of ADPKD-associated missense variants. Extensive contacts among the TOP-domain subunits, the pore and the VSLD provide ample scope for regulation through physical and chemical stimuli.
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14
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Decreased Polycystin 2 Levels Result in Non-Renal Cardiac Dysfunction with Aging. PLoS One 2016; 11:e0153632. [PMID: 27081851 PMCID: PMC4833351 DOI: 10.1371/journal.pone.0153632] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 04/02/2016] [Indexed: 01/25/2023] Open
Abstract
Mutations in the gene for polycystin 2 (Pkd2) lead to polycystic kidney disease, however the main cause of mortality in humans is cardiac related. We previously showed that 5 month old Pkd2+/- mice have altered calcium-contractile activity in cardiomyocytes, but have preserved cardiac function. Here, we examined 1 and 9 month old Pkd2+/- mice to determine if decreased amounts of functional polycystin 2 leads to impaired cardiac function with aging. We observed changes in calcium handling proteins in 1 month old Pkd2+/- mice, and these changes were exacerbated in 9 month old Pkd2+/- mice. Anatomically, the 9 month old Pkd2+/- mice had thinner left ventricular walls, consistent with dilated cardiomyopathy, and the left ventricular ejection fraction was decreased. Intriguingly, in response to acute isoproterenol stimulation to examine β-adrenergic responses, the 9 month old Pkd2+/- mice exhibited a stronger contractile response, which also coincided with preserved localization of the β2 adrenergic receptor. Importantly, the Pkd2+/- mice did not have any renal impairment. We conclude that the cardiac-related impact of decreased polycystin 2 progresses over time towards cardiac dysfunction and altered adrenergic signaling. These results provide further evidence that polycystin 2 provides a critical function in the heart, independent of renal involvement.
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15
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Zheng W, Shen F, Hu R, Roy B, Yang J, Wang Q, Zhang F, King JC, Sergi C, Liu SM, Cordat E, Tang J, Cao Y, Ali D, Chen XZ. Far Upstream Element-Binding Protein 1 Binds the 3' Untranslated Region of PKD2 and Suppresses Its Translation. J Am Soc Nephrol 2016; 27:2645-57. [PMID: 26839368 DOI: 10.1681/asn.2015070836] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 11/24/2015] [Indexed: 01/02/2023] Open
Abstract
Autosomal dominant polycystic kidney disease pathogenesis can be recapitulated in animal models by gene mutations in or dosage alterations of polycystic kidney disease 1 (PKD1) or PKD2, demonstrating that too much and too little PKD1/PKD2 are both pathogenic. Gene dosage manipulation has become an appealing approach by which to compensate for loss or gain of gene function, but the mechanisms controlling PKD2 expression remain incompletely characterized. In this study, using cultured mammalian cells and dual-luciferase assays, we found that the 3' untranslated region (3'UTR) of PKD2 mRNA inhibits luciferase protein expression. We then identified nucleotides 691-1044, which we called 3FI, as the 3'UTR fragment necessary for repressing the expression of luciferase or PKD2 in this system. Using a pull-down assay and mass spectrometry we identified far upstream element-binding protein 1 (FUBP1) as a 3FI-binding protein. In vitro overexpression of FUBP1 inhibited the expression of PKD2 protein but not mRNA. In embryonic zebrafish, FUBP1 knockdown (KD) by morpholino injection increased PKD2 expression and alleviated fish tail curling caused by morpholino-mediated KD of PKD2. Conversely, FUBP1 overexpression by mRNA injection significantly increased pronephric cyst occurrence and tail curling in zebrafish embryos. Furthermore, FUBP1 binds directly to eukaryotic translation initiation factor 4E-binding protein 1, indicating a link to the translation initiation complex. These results show that FUBP1 binds 3FI in the PKD2 3'UTR to inhibit PKD2 translation, regulating zebrafish disease phenotypes associated with PKD2 KD.
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Affiliation(s)
- Wang Zheng
- Membrane Protein Disease and Cancer Research Centre, Provincial Innovation Center, Hubei University of Technology, Wuhan, China; Membrane Protein Disease Research Group, Department of Physiology
| | - Fan Shen
- Membrane Protein Disease Research Group, Department of Physiology, Medical Research Center, Zhongnan Hospital, Wuhan University, Wuhan, China; and
| | - Ruikun Hu
- School of Life Sciences and Technology, Tongji University, Shanghai, China
| | | | - JungWoo Yang
- Membrane Protein Disease Research Group, Department of Physiology
| | - Qian Wang
- Membrane Protein Disease Research Group, Department of Physiology
| | - Fan Zhang
- School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jennifer C King
- Membrane Protein Disease Research Group, Department of Physiology
| | - Consolato Sergi
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Song-Mei Liu
- Medical Research Center, Zhongnan Hospital, Wuhan University, Wuhan, China; and
| | | | - Jingfeng Tang
- Membrane Protein Disease and Cancer Research Centre, Provincial Innovation Center, Hubei University of Technology, Wuhan, China
| | - Ying Cao
- School of Life Sciences and Technology, Tongji University, Shanghai, China
| | | | - Xing-Zhen Chen
- Membrane Protein Disease and Cancer Research Centre, Provincial Innovation Center, Hubei University of Technology, Wuhan, China; Membrane Protein Disease Research Group, Department of Physiology,
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16
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Ta MHT, Liuwantara D, Rangan GK. Effects of pyrrolidine dithiocarbamate on proliferation and nuclear factor-κB activity in autosomal dominant polycystic kidney disease cells. BMC Nephrol 2015; 16:212. [PMID: 26666710 PMCID: PMC4678764 DOI: 10.1186/s12882-015-0193-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 11/24/2015] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Pyrrolidine dithiocarbamate (PDTC) reduces renal cyst growth in a rodent model of polycystic kidney disease (PKD) but the mechanism of action is not clear. Here, we investigated the hypothesis that PDTC reduces the proliferation of cystic epithelial cells in vitro in a nuclear factor (NF)-κB-dependent manner. METHODS Immortalized autosomal dominant PKD (ADPKD) cells that are heterozygous (WT9-7) and homozygous (WT-9-12) for a truncating Pkd1 mutation, and immortalized normal human tubular cells (HK-2), were exposed to NF-κB-inducing agents with or without PDTC. Cell proliferation and apoptosis were assessed by bromodeoxyuridine assay and Annexin V flow cytometry, respectively. NF-κB activity was assessed by luciferase reporter assay and western blotting for nuclear p65, p50, and RelB subunits and cytoplasmic phosphorylated-IκBα. RESULTS Serum-induced proliferation was similar in all cell lines over 72 h. PDTC demonstrated anti-proliferative effects that were delayed in ADPKD cells compared to HK-2. Basal NF-κB-dependent luciferase reporter activity was lower in ADPKD cells compared to normal cells. Classical NF-κB stimulants, lipopolysaccharide (LPS) and tumor necrosis factor (TNF)-α, increased NF-κB luciferase activity in HK-2, whereas in PKD cell lines, NF-κB activity was only induced by TNF-α. However, neither stimulant altered proliferation in any cell line. PDTC reduced TNF-α-stimulated NF-κB activity in HK-2 only. CONCLUSIONS PDTC reduced proliferation in ADPKD cells but did not consistently alter NF-κB activation, suggesting that other signalling pathways are likely to be involved in its ability to attenuate renal cyst growth in vivo.
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Affiliation(s)
- Michelle H T Ta
- Centre for Transplant and Renal Research, Level 5, The Westmead Institute for Medical Research, University of Sydney, 176 Hawkesbury Rd, Westmead, NSW, 2145, Australia.
| | - David Liuwantara
- Centre for Transplant and Renal Research, Level 5, The Westmead Institute for Medical Research, University of Sydney, 176 Hawkesbury Rd, Westmead, NSW, 2145, Australia.
| | - Gopala K Rangan
- Centre for Transplant and Renal Research, Level 5, The Westmead Institute for Medical Research, University of Sydney, 176 Hawkesbury Rd, Westmead, NSW, 2145, Australia.
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17
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Wu H, Chen J, Xu J, Dong Z, Meyuhas O, Chen JK. Blocking rpS6 Phosphorylation Exacerbates Tsc1 Deletion-Induced Kidney Growth. J Am Soc Nephrol 2015; 27:1145-58. [PMID: 26296742 DOI: 10.1681/asn.2014121264] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 07/16/2015] [Indexed: 11/03/2022] Open
Abstract
The molecular mechanisms underlying renal growth and renal growth-induced nephron damage remain poorly understood. Here, we report that in murine models, deletion of the tuberous sclerosis complex protein 1 (Tsc1) in renal proximal tubules induced strikingly enlarged kidneys, with minimal cystogenesis and occasional microscopic tumorigenesis. Signaling studies revealed hyperphosphorylation of eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) and increased phosphorylation of ribosomal protein S6 (rpS6) in activated renal tubules. Notably, knockin of a nonphosphorylatable rpS6 in these Tsc1-mutant mice exacerbated cystogenesis and caused drastic nephron damage and renal fibrosis, leading to kidney failure and a premature death rate of 67% by 9 weeks of age. In contrast, Tsc1 single-mutant mice were all alive and had far fewer renal cysts at this age. Mechanistic studies revealed persistent activation of mammalian target of rapamycin complex 1 (mTORC1) signaling causing hyperphosphorylation and consequent accumulation of 4E-BP1, along with greater cell proliferation, in the renal tubules of Tsc1 and rpS6 double-mutant mice. Furthermore, pharmacologic treatment of Tsc1 single-mutant mice with rapamycin reduced hyperphosphorylation and accumulation of 4E-BP1 but also inhibited phosphorylation of rpS6. Rapamycin also exacerbated cystic and fibrotic lesions and impaired kidney function in these mice, consequently leading to a premature death rate of 40% within 2 weeks of treatment, despite destroying tumors and decreasing kidney size. These findings indicate that Tsc1 prevents aberrant renal growth and tumorigenesis by inhibiting mTORC1 signaling, whereas phosphorylated rpS6 suppresses cystogenesis and fibrosis in Tsc1-deleted kidneys.
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Affiliation(s)
- Huijuan Wu
- Department of Cellular Biology and Anatomy, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Jianchun Chen
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jinxian Xu
- Department of Cellular Biology and Anatomy, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Zheng Dong
- Department of Cellular Biology and Anatomy, Research Department, Charlie Norwood VA Medical Center, Augusta, Georgia; and
| | - Oded Meyuhas
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Jian-Kang Chen
- Department of Cellular Biology and Anatomy, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia;
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18
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Cornec-Le Gall E, Audrézet MP, Le Meur Y, Chen JM, Férec C. Genetics and pathogenesis of autosomal dominant polycystic kidney disease: 20 years on. Hum Mutat 2015; 35:1393-406. [PMID: 25263802 DOI: 10.1002/humu.22708] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 09/22/2014] [Indexed: 12/27/2022]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD), the most common inherited kidney disorder, is characterized by the progressive development and expansion of bilateral fluid-filled cysts derived from the renal tubule epithelial cells. Although typically leading to end-stage renal disease in late middle age, ADPKD represents a continuum, from neonates with hugely enlarged cystic kidneys to cases with adequate kidney function into old age. Since the identification of the first causative gene (i.e., PKD1, encoding polycystin 1) 20 years ago, genetic studies have uncovered a large part of the key factors that underlie the phenotype variability. Here, we provide a comprehensive review of these significant advances as well as those related to disease pathogenesis models, including mutation analysis of PKD1 and PKD2 (encoding polycystin 2), current mutation detection rate, allelic heterogeneity, genotype and phenotype relationships (in terms of three different inheritance patterns: classical autosomal dominant inheritance, complex inheritance, and somatic and germline mosaicism), modifier genes, the role of second somatic mutation hit in renal cystogenesis, and findings from mouse models of polycystic kidney disease. Based upon a combined consideration of the current knowledge, we attempted to propose a unifying framework for explaining the phenotype variability in ADPKD.
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Affiliation(s)
- Emilie Cornec-Le Gall
- Institut National de la Santé et de la Recherche Médicale (INSERM), Brest, France; Faculté de Médecine et des Sciences de la Santé, Université de Bretagne Occidentale, Brest, France; Service de Néphrologie, Hémodialyse et Transplantation Rénale, Centre Hospitalier Régional Universitaire, Hôpital de la Cavale Blanche, Brest, France
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Schmitt SM, Gull M, Brändli AW. Engineering Xenopus embryos for phenotypic drug discovery screening. Adv Drug Deliv Rev 2014; 69-70:225-46. [PMID: 24576445 DOI: 10.1016/j.addr.2014.02.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 02/13/2014] [Accepted: 02/14/2014] [Indexed: 02/08/2023]
Abstract
Many rare human inherited diseases remain untreatable despite the fact that the disease causing genes are known and adequate mouse disease models have been developed. In vivo phenotypic drug screening relies on isolating drug candidates by their ability to produce a desired therapeutic phenotype in whole organisms. Embryos of zebrafish and Xenopus frogs are abundant, small and free-living. They can be easily arrayed in multi-well dishes and treated with small organic molecules. With the development of novel genome modification tools, such a zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and CRISPR/Cas, it is now possible to efficiently engineer non-mammalian models of inherited human diseases. Here, we will review the rapid progress made in adapting these novel genome editing tools to Xenopus. The advantages of Xenopus embryos as in vivo models to study human inherited diseases will be presented and their utility for drug discovery screening will be discussed. Being a tetrapod, Xenopus complements zebrafish as an indispensable non-mammalian animal model for the study of human disease pathologies and the discovery of novel therapeutics for inherited diseases.
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20
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Eccles MR, Stayner CA. Polycystic kidney disease - where gene dosage counts. F1000PRIME REPORTS 2014; 6:24. [PMID: 24765529 PMCID: PMC3974567 DOI: 10.12703/p6-24] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Gene dosage effects have emerged as playing a central role in the pathogenesis of polycystic kidney disease. Yet, how gene dosage can ultimately have an impact on the formation of kidney cysts remains unknown. In this commentary we review the evidence for the role of gene dosage effects versus the “2-hit” mutation model in polycystic kidney disease (PKD), and also discuss how gene networks may potentially make intertwined contributions to PKD.
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21
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Abstract
It has been exciting times since the identification of polycystic kidney disease 1 (PKD1) and PKD2 as the genes mutated in autosomal dominant polycystic kidney disease (ADPKD). Biological roles of the encoded proteins polycystin-1 and TRPP2 have been deduced from phenotypes in ADPKD patients, but recent insights from vertebrate and invertebrate model organisms have significantly expanded our understanding of the physiological functions of these proteins. The identification of additional TRPP (TRPP3 and TRPP5) and polycystin-1-like proteins (PKD1L1, PKD1L2, PKD1L3, and PKDREJ) has added yet another layer of complexity to these fascinating cellular signalling units. TRPP proteins assemble with polycystin-1 family members to form receptor-channel complexes. These protein modules have important biological roles ranging from tubular morphogenesis to determination of left-right asymmetry. The founding members of the polycystin family, TRPP2 and polycystin-1, are a prime example of how studying human disease genes can provide insights into fundamental biological mechanisms using a so-called "reverse translational" approach (from bedside to bench). Here, we discuss the current literature on TRPP ion channels and polycystin-1 family proteins including expression, structure, physical interactions, physiology, and lessons from animal model systems and human disease.
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Affiliation(s)
- Mariam Semmo
- Renal Division, Department of Medicine, University Medical Centre Freiburg, Hugstetter Straße 55, 79106, Freiburg, Germany,
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22
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Freedman BS, Lam AQ, Sundsbak JL, Iatrino R, Su X, Koon SJ, Wu M, Daheron L, Harris PC, Zhou J, Bonventre JV. Reduced ciliary polycystin-2 in induced pluripotent stem cells from polycystic kidney disease patients with PKD1 mutations. J Am Soc Nephrol 2013; 24:1571-86. [PMID: 24009235 PMCID: PMC3785271 DOI: 10.1681/asn.2012111089] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 04/22/2013] [Indexed: 11/03/2022] Open
Abstract
Heterozygous mutations in PKD1 or PKD2, which encode polycystin-1 (PC1) and polycystin-2 (PC2), respectively, cause autosomal dominant PKD (ADPKD), whereas mutations in PKHD1, which encodes fibrocystin/polyductin (FPC), cause autosomal recessive PKD (ARPKD). However, the relationship between these proteins and the pathogenesis of PKD remains unclear. To model PKD in human cells, we established induced pluripotent stem (iPS) cell lines from fibroblasts of three ADPKD and two ARPKD patients. Genetic sequencing revealed unique heterozygous mutations in PKD1 of the parental ADPKD fibroblasts but no pathogenic mutations in PKD2. Undifferentiated PKD iPS cells, control iPS cells, and embryonic stem cells elaborated primary cilia and expressed PC1, PC2, and FPC at similar levels, and PKD and control iPS cells exhibited comparable rates of proliferation, apoptosis, and ciliogenesis. However, ADPKD iPS cells as well as somatic epithelial cells and hepatoblasts/biliary precursors differentiated from these cells expressed lower levels of PC2 at the cilium. Additional sequencing confirmed the retention of PKD1 heterozygous mutations in iPS cell lines from two patients but identified possible loss of heterozygosity in iPS cell lines from one patient. Furthermore, ectopic expression of wild-type PC1 in ADPKD iPS-derived hepatoblasts rescued ciliary PC2 protein expression levels, and overexpression of PC1 but not a carboxy-terminal truncation mutant increased ciliary PC2 expression levels in mouse kidney cells. Taken together, these results suggest that PC1 regulates ciliary PC2 protein expression levels and support the use of PKD iPS cells for investigating disease pathophysiology.
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Affiliation(s)
- Benjamin S. Freedman
- Renal Division and Harvard Center for Polycystic Kidney Disease Research, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Albert Q. Lam
- Renal Division and Harvard Center for Polycystic Kidney Disease Research, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
- Harvard Stem Cell Institute, Harvard University, Cambridge and Boston Massachusetts
| | - Jamie L. Sundsbak
- Mayo Translational Polycystic Kidney Disease Center, Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota; and
| | - Rossella Iatrino
- Renal Division and Harvard Center for Polycystic Kidney Disease Research, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
- Nephrology, Dialysis, and Transplant Division, Policlinico Universitario di Modena, Modena, Italy
| | - Xuefeng Su
- Renal Division and Harvard Center for Polycystic Kidney Disease Research, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Sarah J. Koon
- Mayo Translational Polycystic Kidney Disease Center, Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota; and
| | - Maoqing Wu
- Renal Division and Harvard Center for Polycystic Kidney Disease Research, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Laurence Daheron
- Harvard Stem Cell Institute, Harvard University, Cambridge and Boston Massachusetts
| | - Peter C. Harris
- Mayo Translational Polycystic Kidney Disease Center, Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota; and
| | - Jing Zhou
- Renal Division and Harvard Center for Polycystic Kidney Disease Research, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
- Harvard Stem Cell Institute, Harvard University, Cambridge and Boston Massachusetts
| | - Joseph V. Bonventre
- Renal Division and Harvard Center for Polycystic Kidney Disease Research, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
- Harvard Stem Cell Institute, Harvard University, Cambridge and Boston Massachusetts
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Ko JY, Yoo KH, Song SA, Kim DY, Kong HK, Ahn C, Lee HW, Kang DH, Oh GT, Park JH. Inactivation of max-interacting protein 1 induces renal cilia disassembly through reduction in levels of intraflagellar transport 20 in polycystic kidney. J Biol Chem 2013; 288:6488-97. [PMID: 23316056 DOI: 10.1074/jbc.m112.413302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cilia in ciliated cells consist of protruding structures that sense mechanical and chemical signals from the extracellular environment. Cilia are assembled with variety molecules via a process known as intraflagellar transport (IFT). What controls the length of cilia in ciliated cells is critical to understand ciliary disease such as autosomal dominant polycystic kidney disease, which involves abnormally short cilia. But this control mechanism is not well understood. Previously, multiple tubular cysts have been observed in the kidneys of max-interacting protein 1 (Mxi1)-deficient mice aged 6 months or more. Here, we clarified the relationship between Mxi1 inactivation and cilia disassembly. Cilia phenotypes were observed in kidneys of Mxi1-deficient mice using scanning electron microscopy to elucidate the effect of Mxi1 on renal cilia phenotype, and cilia disassembly was observed in Mxi1-deficient kidney. In addition, genes related to cilia were validated in vitro and in vivo using quantitative PCR, and Ift20 was selected as a candidate gene in this study. The length of cilium decreased, and p-ERK level induced by a cilia defect increased in kidneys of Mxi1-deficient mice. Ciliogenesis of Mxi1-deficient mouse embryonic fibroblasts (MEFs) decreased, and this abnormality was restored by Mxi1 transfection in Mxi1-deficient MEFs. We confirmed that ciliogenesis and Ift20 expression were regulated by Mxi1 in vitro. We also determined that Mxi1 regulates Ift20 promoter activity via Ets-1 binding to the Ift20 promoter. These results indicate that inactivating Mxi1 induces ciliary defects in polycystic kidney.
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Affiliation(s)
- Je Yeong Ko
- From the Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Republic of Korea
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24
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Construction of a transgenic pig model overexpressing polycystic kidney disease 2 (PKD2) gene. Transgenic Res 2013; 22:861-7. [PMID: 23315160 DOI: 10.1007/s11248-012-9686-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 12/28/2012] [Indexed: 12/13/2022]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is a common human genetic disease, affecting millions of people worldwide. The progressive growth of cysts in kidneys eventually leads to renal failure in 50 % of patients, and there is currently no effective treatment. Various murine models have been studied to elucidate the disease mechanisms, and much information has been acquired. However, the course of the disease cannot be fully recapitulated using these models. The pig is a suitable model for biomedical research, and pig PKD2 has high similarity to the human ortholog at the molecular level. Here, a mini-pig PKD2 transgenic model was generated, driven by a ubiquitous cytomegalovirus enhancer/promoter. Using somatic cell nuclear transfer, four transgenic pigs with approximately 10 insertion events each were generated. Quantitative real-time PCR and western blotting showed that PKD2 was more highly expressed in transgenic pigs than in wild-type counterparts. Because of the chronic nature of ADPKD, blood urea nitrogen and serum creatinine levels were continuously measured to assess the pig kidney function. The transgenic pigs continue to show no significant alteration in kidney function; it is estimated that 1-2 more years may be required for manifestation of renal cystogenesis in these pigs.
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25
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Hwang JH, Park HC, Jeong JC, Ha Baek S, Han MY, Bang K, Cho JY, Yu SH, Yang J, Oh KH, Hwang YH, Ahn C. Chronic asymptomatic pyuria precedes overt urinary tract infection and deterioration of renal function in autosomal dominant polycystic kidney disease. BMC Nephrol 2013; 14:1. [PMID: 23295127 PMCID: PMC3545884 DOI: 10.1186/1471-2369-14-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 12/19/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Urinary tract infection (UTI) occurs in 30%-50% of individuals with autosomal dominant polycystic kidney disease (ADPKD). However, the clinical relevance of asymptomatic pyuria in ADPKD patients remains unknown. METHODS We retrospectively reviewed medical records of 256 ADPKD patients who registered to the ADPKD clinic at Seoul National University Hospital from Aug 1999 to Aug 2010. We defined the asymptomatic pyuria as more than 5-9 white blood cells in high-power field with no related symptoms or signs of overt UTI. Patients were categorized into 2 groups depending on its duration and frequency: Group A included non-pyuria and transient pyuria patients; Group B included recurrent and persistent pyuria patients. The association between asymptomatic pyuria and both the development of overt UTI and the deterioration of renal function were examined. RESULTS With a mean follow-up duration of 65.3 months, 176 (68.8%) out of 256 patients experienced 681 episodes of asymptomatic pyuria and 50 episodes of UTI. The annual incidence of asymptomatic pyuria was 0.492 episodes/patient/year. The patients in group B showed female predominance (58.5% vs. 42.0%, P=0.01) and experienced an upper UTI more frequently (hazard ratio: 4.612, 95% confidence interval: 1.735-12.258; P=0.002, adjusted for gender and hypertension). The annual change in estimated glomerular filtration rate (ΔeGFR) was significantly larger in magnitude in group B than in group A (-2.7±4.56 vs. -1.17±5.8, respectively; P=0.01). Age and Group B found to be the independent variables for ΔeGFR and developing end-stage renal disease (16.0% vs. 4.3%, respectively; P=0.001). CONCLUSIONS Chronic asymptomatic pyuria may increase the risk of developing overt UTI and may contribute to declining renal function in ADPKD.
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Affiliation(s)
- Jin Ho Hwang
- Department of Internal Medicine, Seoul National University Hospital, 101 Daehak-no, Jongno-gu, Seoul, 110-744, South Korea
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26
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Hwang JH, Park HC, Jeong JC, Ha Baek S, Han MY, Bang K, Cho JY, Yu SH, Yang J, Oh KH, Hwang YH, Ahn C. Chronic asymptomatic pyuria precedes overt urinary tract infection and deterioration of renal function in autosomal dominant polycystic kidney disease. BMC Nephrol 2013. [PMID: 23295127 DOI: 10.1186/1471-2369-14-79/tables/3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023] Open
Abstract
BACKGROUND Urinary tract infection (UTI) occurs in 30%-50% of individuals with autosomal dominant polycystic kidney disease (ADPKD). However, the clinical relevance of asymptomatic pyuria in ADPKD patients remains unknown. METHODS We retrospectively reviewed medical records of 256 ADPKD patients who registered to the ADPKD clinic at Seoul National University Hospital from Aug 1999 to Aug 2010. We defined the asymptomatic pyuria as more than 5-9 white blood cells in high-power field with no related symptoms or signs of overt UTI. Patients were categorized into 2 groups depending on its duration and frequency: Group A included non-pyuria and transient pyuria patients; Group B included recurrent and persistent pyuria patients. The association between asymptomatic pyuria and both the development of overt UTI and the deterioration of renal function were examined. RESULTS With a mean follow-up duration of 65.3 months, 176 (68.8%) out of 256 patients experienced 681 episodes of asymptomatic pyuria and 50 episodes of UTI. The annual incidence of asymptomatic pyuria was 0.492 episodes/patient/year. The patients in group B showed female predominance (58.5% vs. 42.0%, P=0.01) and experienced an upper UTI more frequently (hazard ratio: 4.612, 95% confidence interval: 1.735-12.258; P=0.002, adjusted for gender and hypertension). The annual change in estimated glomerular filtration rate (ΔeGFR) was significantly larger in magnitude in group B than in group A (-2.7±4.56 vs. -1.17±5.8, respectively; P=0.01). Age and Group B found to be the independent variables for ΔeGFR and developing end-stage renal disease (16.0% vs. 4.3%, respectively; P=0.001). CONCLUSIONS Chronic asymptomatic pyuria may increase the risk of developing overt UTI and may contribute to declining renal function in ADPKD.
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Affiliation(s)
- Jin Ho Hwang
- Department of Internal Medicine, Seoul National University Hospital, 101 Daehak-no, Jongno-gu, Seoul, 110-744, South Korea
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The TRPP Signaling Module: TRPP2/Polycystin-1 and TRPP2/PKD1L1. METHODS IN PHARMACOLOGY AND TOXICOLOGY 2012. [DOI: 10.1007/978-1-62703-077-9_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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28
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Janssen MJ, Waanders E, Te Morsche RHM, Xing R, Dijkman HBPM, Woudenberg J, Drenth JPH. Secondary, somatic mutations might promote cyst formation in patients with autosomal dominant polycystic liver disease. Gastroenterology 2011; 141:2056-2063.e2. [PMID: 21856269 DOI: 10.1053/j.gastro.2011.08.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 07/22/2011] [Accepted: 08/08/2011] [Indexed: 01/02/2023]
Abstract
BACKGROUND & AIMS Heterozygous germline mutations in PRKCSH cause autosomal dominant polycystic liver disease (PCLD), but it is not clear how they lead to cyst formation. We investigated whether mutations in cyst epithelial cells and corresponding loss of the PRKCSH gene product (hepatocystin) contributed to cyst development. METHODS Liver cyst material was collected through laparoscopic cyst fenestration from 8 patients with PCLD who had a heterozygous germline mutation in PRKCSH. Tissue sections from 71 cysts (2-14 per patient) were obtained for hepatocystin staining and mutation analysis. Cyst epithelium was acquired using laser microdissection; DNA was isolated and analyzed for loss of heterozygosity (LOH) and somatic mutations using restriction analysis and sequencing. Common single nucleotide polymorphisms (SNPs) in a 70-kilobase region surrounding the germline mutation were used to determine variations in the genomic region with LOH. RESULTS The wild-type allele of PRKCSH was lost (LOH) in 76% of cysts (54/71). Hepatocystin was not detected in cyst epithelia with LOH, whereas heterozygous cysts still expressed hepatocystin. The variation observed in the LOH region analysis indicates that cysts develop independently. We also detected somatic mutations in PRKCSH in 17% (2/12) of the cysts without LOH. Trans-heterozygous mutations in SEC63 were not observed. CONCLUSIONS Among patients with PCLD who have a heterozygous germline mutation in PRKCSH, we found secondary, somatic mutations (second hits) in more than 76% of the liver cyst epithelia. PCLD is recessive at the cellular level, and loss of functional PRKCSH is an important step in cystogenesis.
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Affiliation(s)
- Manoe J Janssen
- Department of Gastroenterology and Hepatology, Institute for Genetic and Metabolic Disease, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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Abstract
The founding member of the TRPP family, TRPP2, was identified as one of the disease genes causing autosomal dominant polycystic kidney disease (ADPKD). ADPKD is the most prevalent, potentially lethal, monogenic disorder in humans, with an average incidence of one in 400 to one in 1,000 individuals worldwide. Here we give an overview of TRPP ion channels and Polycystin-1 receptor proteins focusing on more recent studies. We include the Polycystin-1 family since these proteins are functionally linked to TRPP channels.
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30
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Lancaster MA, Gleeson JG. Cystic kidney disease: the role of Wnt signaling. Trends Mol Med 2010; 16:349-60. [PMID: 20576469 PMCID: PMC2919646 DOI: 10.1016/j.molmed.2010.05.004] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 05/19/2010] [Accepted: 05/19/2010] [Indexed: 02/07/2023]
Abstract
Wnt signaling encompasses a variety of signaling cascades that can be activated by secreted Wnt ligands. Two such pathways, the canonical or beta-catenin pathway and the planar cell polarity (PCP) pathway, have recently received attention for their roles in multiple cellular processes within the kidney. Both of these pathways are important for kidney development as well as homeostasis and injury repair. The disruption of either pathway can lead to cystic kidney disease, a class of genetic diseases that includes the most common hereditary life-threatening syndrome polycystic kidney disease (PKD). Recent evidence implicates canonical and noncanonical Wnt pathways in cyst formation and points to a remarkable role for developmental processes in the adult kidney.
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Affiliation(s)
- Madeline A Lancaster
- Biomedical Sciences Program, Howard Hughes Medical Institutes, Department of Neurosciences, University of California, San Diego, USA.
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31
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Takakura A, Contrino L, Zhou X, Bonventre JV, Sun Y, Humphreys BD, Zhou J. Renal injury is a third hit promoting rapid development of adult polycystic kidney disease. Hum Mol Genet 2009; 18:2523-31. [PMID: 19342421 DOI: 10.1093/hmg/ddp147] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The 'two-hit' model is a widely accepted genetic mechanism for progressive cyst formation in autosomal dominant polycystic kidney disease. We have previously shown that adult inactivation of Pkd1 using the Mx1Cre(+) allele causes a late onset of focal cystic disease. An explanation for the delayed appearance of cysts is the requirement for an additional independent factor, or 'third hit'. Here we show that renal injury leads to massive cystic disease in the same mouse line. Cysts are labeled with a collecting duct/tubule marker, Lectin Dolichos biflorus Agglutinin, which correlates with the site of Cre-mediated recombination in the collecting system. 5-Bromo-2'-deoxyuridine labeling reveals that cyst-lining epithelial cells are comprised of regenerated cells in response to renal injury. These data demonstrate, for the first time, a role for polycystin-1 in kidney injury and repair and indicate that renal injury constitutes a 'third hit' resulting in rapid cyst formation in adulthood.
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Affiliation(s)
- Ayumi Takakura
- Renal Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 4 Blackfan Circle, Boston, MA 02115, USA
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32
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Affiliation(s)
- Jing Zhou
- Renal Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115;
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33
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Takakura A, Contrino L, Beck AW, Zhou J. Pkd1 inactivation induced in adulthood produces focal cystic disease. J Am Soc Nephrol 2008; 19:2351-63. [PMID: 18776127 DOI: 10.1681/asn.2007101139] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Autosomal dominant polycystic kidney disease, the most common monogenetic disorder, is characterized by gradual replacement of normal renal parenchyma by fluid-filled cysts. Mutations in either PKD1 or PKD2 cause autosomal dominant polycystic kidney disease. Pkd1(-/-) or Pkd2(-/-) mice develop rapid renal cystic disease and exhibit embryonic lethality; this supports the "two-hit" hypothesis, which proposes that a germline mutation in PKD1 (or PKD2) followed by a second somatic mutation later in life is responsible for the phenotype. Here, for investigation of the loss of Pkd1 at specific times of development, an inducible Pkd1-knockout mouse model was generated. Inactivation of Pkd1 in 5-wk-old mice resulted in formation of only focal renal cysts 6 to 9 wk later but in a severe polycystic phenotype nearly 1 yr later. Cysts derived from either collecting tubules or distal tubules but not from proximal tubules, which correlated with sites of Cre-mediated recombination. Inactivation of Pkd1 in 1-wk-old mice, however, resulted in massive cyst disease 6 wk later, despite a similar pattern of Cre-mediated recombination between 1- and 5-wk-old kidneys. Moreover, a germline heterozygous Pkd1 mutation facilitated cyst formation when a somatic Pkd1 mutation was induced. A marked increase in proliferating cell nuclear antigen expression was observed in cyst-lining epithelia and in normal-looking tubules adjacent to but not in those distant from cysts. These data suggest that Pkd1 inactivation is not sufficient to initiate the cell proliferation necessary for cyst formation; a paracrine mechanism may account for focal cell proliferation and regional disease progression. We propose that an additional genetic or nongenetic "third hit" may be required for rapid development of cysts in polycystic kidney disease.
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Affiliation(s)
- Ayumi Takakura
- Renal Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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34
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Wei F, Karihaloo A, Yu Z, Marlier A, Seth P, Shibazaki S, Wang T, Sukhatme VP, Somlo S, Cantley LG. Neutrophil gelatinase-associated lipocalin suppresses cyst growth by Pkd1 null cells in vitro and in vivo. Kidney Int 2008; 74:1310-1318. [PMID: 18974761 DOI: 10.1038/ki.2008.395] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cyst growth in patients with autosomal dominant polycystic kidney disease is thought to be due to increased tubular cell proliferation. One model to explain this altered proliferation suggests that the polycystin proteins PC1 and PC2 localize to apical cilia and serve as an integral part of the flow-sensing pathway thus modulating the proliferative response. We measured proliferation and apoptosis in proximal tubule derived cell lines lacking PC1. These cells showed increased rates of proliferation, a decreased rate of apoptosis, compared to control heterozygous cell lines, and spontaneously formed cysts rather than tubules in an in vitro tubulogenesis assay. Addition of neutrophil gelatinase associated lipocalin (NGAL), a small secreted protein that binds diverse ligands, to the cells lacking PC1 inhibited proliferation and increased apoptosis leading to slower cyst growth in vitro. Sustained over-expression at low level of NGAL by an adenoviral delivery system suppressed cyst enlargement without improving renal function in the Pkd1 mutant mice. Our studies show that renal epithelial cells lacking PC1 have an inherent tendency to hyper-proliferate forming cysts in vitro independent of a flow stimulus. The potential benefit of attenuating cyst growth with NGAL remains to be determined.
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Affiliation(s)
- Feng Wei
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Anil Karihaloo
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Zhiheng Yu
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Arnaud Marlier
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Pankaj Seth
- Section of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Sekiya Shibazaki
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Tong Wang
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Vikas P Sukhatme
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Stefan Somlo
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Lloyd G Cantley
- Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut, USA
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35
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Starremans PG, Li X, Finnerty PE, Guo L, Takakura A, Neilson EG, Zhou J. A mouse model for polycystic kidney disease through a somatic in-frame deletion in the 5' end of Pkd1. Kidney Int 2008; 73:1394-405. [PMID: 18385665 DOI: 10.1038/ki.2008.111] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Autosomal dominant polycystic kidney disease, a leading cause of end-stage renal disease in adults, is characterized by progressive focal cyst formation in the kidney. Embryonic lethality of Pkd1-targeted mice limits the use of these mice. Here we developed a floxed allele of Pkd1 exons 2-6. Global deletion mutants developed polyhydramnios, hydrops fetalis, polycystic kidney and pancreatic disease. Somatic Pkd1 inactivation in the kidney was achieved by crossing Pkd1(flox) mice with transgenic mice expressing Cre controlled by a gamma-glutamyltranspeptidase promoter. These mutants developed cysts in both proximal and distal nephron segments and survived for about 4 weeks. Somatic loss of heterozygosity was shown in a reporter mouse strain to cause cystogenesis. Some cysts in young mice are positive for multiple tubular markers and a mesenchymal marker, suggesting a delay in tubular epithelial differentiation. A higher cell proliferation rate was observed in distal nephron segments probably accounting for the faster growth rate of distal cysts. Although we observed an overall increase in apoptosis in cystic kidneys, there was no difference between proximal or distal nephron segments. We also found increased cyclic AMP, aquaporin 2 and vasopressin type 2 receptor mRNA levels, and apical membrane translocation of aquaporin 2 in cystic kidneys, all of which may contribute to the differential cyst growth rate observed. The accelerated polycystic kidney phenotype of these mice provides an excellent model for studying molecular pathways of cystogenesis and to test therapeutic strategies.
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Affiliation(s)
- P G Starremans
- Department of Medicine, Renal Division, Harvard Institutes of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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36
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Tian Y, Kolb R, Hong JH, Carroll J, Li D, You J, Bronson R, Yaffe MB, Zhou J, Benjamin T. TAZ promotes PC2 degradation through a SCFbeta-Trcp E3 ligase complex. Mol Cell Biol 2007; 27:6383-95. [PMID: 17636028 PMCID: PMC2099608 DOI: 10.1128/mcb.00254-07] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Studies of a TAZ knockout mouse reveal a novel function of the transcriptional regulator TAZ, that is, as a binding partner of the F-box protein beta-Trcp. TAZ-/- mice develop polycystic kidney disease (PKD) and emphysema. The calcium-permeable cation channel protein polycystin 2 (PC2) is overexpressed in kidneys of TAZ-/- mice as a result of decreased degradation via an SCF(beta-Trcp) E3 ubiquitin ligase pathway. Replacements of serines in a phosphodegron motif in TAZ prevent beta-Trcp binding and PC2 degradation. Coexpression of a cytoplasmic fragment of polycystin 1 blocks the PC2-TAZ interaction and prevents TAZ-mediated degradation of PC2. Depletion of TAZ in zebrafish also results in a cystic kidney accompanied by overexpression of PC2. These results establish a common role of TAZ across vertebrate species in a protein degradation pathway regulated by phosphorylation and implicate deficiencies in this pathway in the development of PKD.
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Affiliation(s)
- Yu Tian
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
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37
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Nauli SM, Rossetti S, Kolb RJ, Alenghat FJ, Consugar MB, Harris PC, Ingber DE, Loghman-Adham M, Zhou J. Loss of polycystin-1 in human cyst-lining epithelia leads to ciliary dysfunction. J Am Soc Nephrol 2006; 17:1015-25. [PMID: 16565258 DOI: 10.1681/asn.2005080830] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
A "two-hit" hypothesis predicts a second somatic hit, in addition to the germline mutation, as a prerequisite to cystogenesis and has been proposed to explain the focal nature for renal cyst formation in autosomal dominant polycystic kidney disease (ADPKD). It was reported previously that Pkd1(null/null) mouse kidney epithelial cells are unresponsive to flow stimulation. This report shows that Pkd1(+/null) cells are capable of responding to mechanical flow stimulation by changing their intracellular calcium concentration in a manner similar to that of wild-type cells. This paper reports that human renal epithelia require a higher level of shear stress to evoke a cytosolic calcium increase than do mouse renal epithelia. Both immortalized and primary cultured renal epithelial cells that originate from normal and nondilated ADPKD human kidney tubules display normal ciliary expression of the polycystins and respond to fluid-flow shear stress with the typical change in cytosolic calcium. In contrast, immortalized and primary cultured cyst-lining epithelial cells from ADPKD patients with mutations in PKD1 or with abnormal ciliary expression of polycystin-1 or -2 were not responsive to fluid shear stress. These data support a two-hit hypothesis as a mechanism of cystogenesis. This report proposes that calcium response to fluid-flow shear stress can be used as a readout of polycystin function and that loss of mechanosensation in the renal tubular epithelia is a feature of PKD cysts.
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Affiliation(s)
- Surya M Nauli
- Harvard Institutes of Medicine, Suite 520, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
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38
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Yamaguchi T, Hempson SJ, Reif GA, Hedge AM, Wallace DP. Calcium Restores a Normal Proliferation Phenotype in Human Polycystic Kidney Disease Epithelial Cells. J Am Soc Nephrol 2005; 17:178-87. [PMID: 16319189 DOI: 10.1681/asn.2005060645] [Citation(s) in RCA: 216] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Polycystic kidney disease (PKD) is a lethal disorder characterized by progressive expansion of renal cysts. Genetic mutations associated with PKD are thought to disrupt intracellular Ca2+ regulation, leading to abnormal proliferation of tubule epithelial cells. cAMP stimulates the B-Raf/MEK/extracellular signal-regulated kinase (B-Raf/MEK/ERK) pathway and accelerates the proliferation of cells that are cultured from PKD cysts. By contrast, cAMP inhibits the proliferation of cells from normal human kidneys (NHK) and M-1 mouse collecting duct cells. Previously, it was found that a sustained reduction of intracellular Ca2+ levels in NHK and M-1 cells that were treated with Ca2+ entry blockers allowed cAMP activation of the B-Raf/MEK/ERK pathway, switching the cells to a cAMP-growth stimulated phenotype. In this study, primary cultures of cyst epithelial cells from autosomal dominant (ADPKD) and recessive (ARPKD) PKD kidneys were used to determine whether controlled addition of Ca2+ could reverse the aberrant mitogenic response to cAMP. Steady-state intracellular Ca2+ levels were found to be 20 nM lower in cyst-derived ADPKD cells (57 +/- 2 nM) compared with NHK cells (77 +/- 2 nM). Treatment of ADPKD cells or ARPKD cells with either Bay K8644, a Ca2+ channel activator, or A23187, a Ca2+ ionophore, caused sustained increases in intracellular Ca2+ levels and completely reversed the mitogenic response to cAMP. Elevation of intracellular Ca2+ levels in ADPKD cells increased Akt activity and blocked cAMP-dependent B-Raf and ERK activation. Thus, increases in [Ca2+]i are able to restore the normal anti-mitogenic response to cAMP in cells that are derived from two genetically distinct forms of PKD.
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Affiliation(s)
- Tamio Yamaguchi
- Kidney Institute, Department of Medicine, University of Kansas Medical Center, 3901 Rainbow Boulevard, MSN 3018, Kansas City, KS 66160, USA
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Li X, Luo Y, Starremans PG, McNamara CA, Pei Y, Zhou J. Polycystin-1 and polycystin-2 regulate the cell cycle through the helix-loop-helix inhibitor Id2. Nat Cell Biol 2005; 7:1202-12. [PMID: 16311606 DOI: 10.1038/ncb1326] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Accepted: 11/14/2005] [Indexed: 01/14/2023]
Abstract
Autosomal-dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease and is characterized by progressive cyst formation and ultimate loss of renal function. Increased cell proliferation is a key feature of the disease. Here, we show that the ADPKD protein polycystin-2 (PC2) regulates the cell cycle through direct interaction with Id2, a member of the helix-loop-helix (HLH) protein family that is known to regulate cell proliferation and differentiation. Id2 expression suppresses the induction of a cyclin-dependent kinase inhibitor, p21, by either polycystin-1 (PC1) or PC2. The PC2-Id2 interaction is regulated by PC1-dependent phosphorylation of PC2. Enhanced Id2 nuclear localization is seen in human and mouse cystic kidneys. Inhibition of Id2 expression by RNA interference corrects the hyperproliferative phenotype of PC1 mutant cells. We propose that Id2 has a crucial role in cell-cycle regulation that is mediated by PC1 and PC2.
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Affiliation(s)
- Xiaogang Li
- Renal Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
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40
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Zoja C, Morigi M, Benigni A, Remuzzi G. Genetics of rare diseases of the kidney: learning from mouse models. Cytogenet Genome Res 2005; 105:479-84. [PMID: 15237237 DOI: 10.1159/000078222] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Accepted: 11/03/2003] [Indexed: 11/19/2022] Open
Affiliation(s)
- C Zoja
- Mario Negri Institute for Pharmacological Research, Bergamo, Italy
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41
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Lantinga-van Leeuwen IS, Dauwerse JG, Baelde HJ, Leonhard WN, van de Wal A, Ward CJ, Verbeek S, Deruiter MC, Breuning MH, de Heer E, Peters DJM. Lowering of Pkd1 expression is sufficient to cause polycystic kidney disease. Hum Mol Genet 2004; 13:3069-77. [PMID: 15496422 DOI: 10.1093/hmg/ddh336] [Citation(s) in RCA: 238] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is a major cause of renal failure and is characterized by the formation of many fluid-filled cysts in the kidneys. It is a systemic disorder that is caused by mutations in PKD1 or PKD2. Homozygous inactivation of these genes at the cellular level, by a 'two-hit' mechanism, has been implicated in cyst formation but does not seem to be the sole mechanism for cystogenesis. We have generated a novel mouse model with a hypomorphic Pkd1 allele, Pkd1(nl), harbouring an intronic neomycin-selectable marker. This selection cassette causes aberrant splicing of intron 1, yielding only 13-20% normally spliced Pkd1 transcripts in the majority of homozygous Pkd1(nl) mice. Homozygous Pkd1(nl) mice are viable, showing bilaterally enlarged polycystic kidneys. This is in contrast to homozygous knock-out mice, which are embryonic lethal, and heterozygous knock-out mice that show only a very mild cystic phenotype. In addition, homozygous Pkd1(nl) mice showed dilatations of pancreatic and liver bile ducts, and the mice had cardiovascular abnormalities, pathogenic features similar to the human ADPKD phenotype. Removal of the neomycin selection-cassette restored the phenotype of wild-type mice. These results show that a reduced dosage of Pkd1 is sufficient to initiate cystogenesis and vascular defects and indicate that low Pkd1 gene expression levels can overcome the embryonic lethality seen in Pkd1 knock-out mice. We propose that in patients reduced PKD1 expression of the normal allele below a critical level, due to genetic, environmental or stochastic factors, may lead to cyst formation in the kidneys and other clinical features of ADPKD.
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Abstract
The external surfaces of the human body, as well as its internal organs, constantly experience different kinds of mechanical stimulations. For example, tubular epithelial cells of the kidney are continuously exposed to a variety of mechanical forces, such as fluid flow shear stress within the lumen of th nephron. The majority of epithelial cells along the nephron, except intercalated cells, possess a primary cilium, an organelle projecting from the cell's apical surface into the luminal space. Despite its discovery over 100 years ago, the primary cilium's function continued to elude researchers for many decades. However, recent studies indicate that renal cilia have a sensory function. Studies on polycystic kidney disease (PKD) have identified many of the molecular players, which should help solve the mystery of how the renal cilium senses fluid flow. In this review, we will summarize the recent breakthroughs in PKD research and discuss the role(s) of the polycystin signaling complex in mediating mechanosensory function by the primary cilium of renal epithelium as well as of the embryonic node.
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Affiliation(s)
- Surya M Nauli
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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43
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Loghman-Adham M, Soto CE, Inagami T, Cassis L. The intrarenal renin-angiotensin system in autosomal dominant polycystic kidney disease. Am J Physiol Renal Physiol 2004; 287:F775-88. [PMID: 15187005 DOI: 10.1152/ajprenal.00370.2003] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Hypertension is a common complication of autosomal dominant polycystic kidney disease (ADPKD), often present before the onset of renal failure. A role for the renin-angiotensin system (RAS) has been proposed, but studies of systemic RAS have failed to show a correlation between plasma renin activity and blood pressure in ADPKD. Ectopic renin expression by cyst epithelium was first reported in 1992 (Torres VE, Donovan KA, Sicli G, Holley KE, Thibodeau ST, Carretero OA, Inagami T, McAteer JA, and Johnson CM. Kidney Int 42: 364-373, 1992). It is not known, however, whether other RAS components are also expressed by cysts in ADPKD. We show that, in addition to renin, angiotensinogen (AGT) is produced by some cysts and dilated tubules. Angiotensin-converting enzyme, ANG II type 1 receptor, and ANG II peptide are also present within cysts and in many tubules; and some cyst fluids contain high ANG II concentrations. Additionally, cyst-derived cells in culture continue to express the components of the RAS at both the protein and mRNA levels. We further show that renin is expressed primarily in cysts of distal tubule origin and in cyst-derived cells with distal tubule characteristics, whereas AGT is expressed primarily in cysts of proximal tubule origin and in cyst-derived cells with proximal tubule characteristics. Renin production by cyst-derived cells appears to be regulated by extracellular Na+ concentration. Based on these observations, we propose a model of an autocrine/paracrine RAS in polycystic kidney disease, whereby overactivity of the intrarenal system results in sustained increases in intratubular ANG II concentrations.
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MESH Headings
- Angiotensin II/genetics
- Angiotensin II/immunology
- Angiotensin II/metabolism
- Angiotensinogen/genetics
- Angiotensinogen/immunology
- Angiotensinogen/metabolism
- Animals
- Antibodies
- Blotting, Western
- Cells, Cultured
- Humans
- Hypertension, Renal/metabolism
- Hypertension, Renal/physiopathology
- Kidney/metabolism
- Peptidyl-Dipeptidase A/genetics
- Peptidyl-Dipeptidase A/immunology
- Peptidyl-Dipeptidase A/metabolism
- Polycystic Kidney, Autosomal Dominant/metabolism
- Polycystic Kidney, Autosomal Dominant/physiopathology
- RNA, Messenger/analysis
- Rabbits
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/immunology
- Receptor, Angiotensin, Type 1/metabolism
- Renin/genetics
- Renin/immunology
- Renin/metabolism
- Renin-Angiotensin System/physiology
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Affiliation(s)
- Mahmoud Loghman-Adham
- Department of Pediatrics and Pediatric Research Institute, Saint Louis University, St. Louis, Missouri 07920, USA.
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Zhang B, Fugleholm K, Day LB, Ye S, Weller RO, Day INM. Molecular pathogenesis of subarachnoid haemorrhage. Int J Biochem Cell Biol 2003; 35:1341-60. [PMID: 12798348 DOI: 10.1016/s1357-2725(03)00043-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Subarachnoid haemorrhage (SAH) results from leakage of blood into the subarachnoid space and carries high morbidity and mortality. However, there is limited understanding to date, of the risk factors, cellular, intermediate biochemical and genetic traits predisposing to SAH. Nevertheless, in conjunction with improved methods of diagnostic imaging and less invasive approaches to preventing aneurysmal rupture, there may be utility in gaining a better understanding of the pathogenesis and in identifying pre-disease markers. Additionally, it is not impossible that drugs of value (e.g. matrix or endothelial modifiers) could become available. Several different clinical subtypes can be recognised, distinguished by arterial or venous involvement, presence of unruptured arterial aneurysms, and apparently "sporadic" and "familial" occurrences. Epidemiological risk factors include alcohol consumption and smoking: hypertension is a risk factor for rupture. About 10% seem to reflect strong family history and this subset may be particularly illuminating with respect to the molecular pathogenesis. Haemodynamic stress and poor vascular structure may be the main mechanisms of pathogenesis. The epidemiological and statistical evidence for familial megaphenic genes and modifier genes is reviewed. This review focuses on the pathogenesis, as opposed to inflammatory response to SAH. It sets in context the roles of specific genes and their protein products, such as polycystin (PKD1), fibrillin (FBN1), collagen III (COL3A1), elastin (ELN), collagen IV, protease inhibitor or alpha1-antitrypsin (PI) and proteases. These considerations illustrate the shortfalls in current knowledge, the needs of future biochemical and cellular research and their potential implications for future prevention of this often fatal condition.
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Affiliation(s)
- Baiping Zhang
- Human Genetics Division, School of Medicine, Southampton University Hospital NHS Trust, Duthie Building (Mailpoint 808), Tremona Road, Southampton SO16 6YD, UK
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45
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Smyth BJ, Snyder RW, Balkovetz DF, Lipschutz JH. Recent advances in the cell biology of polycystic kidney disease. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 231:51-89. [PMID: 14713003 DOI: 10.1016/s0074-7696(03)31002-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is a significant familial disorder, crossing multiple ethnicities as well as organ systems. The goal of understanding and, ultimately, curing ADPKD has fostered collaborative efforts among many laboratories, mustered on by the opportunity to probe fundamental cellular biology. Here we review what is known about ADPKD including well-accepted data such as the identification of the causative genes and the fact that PKD1 and PKD2 act in the same pathway, fairly well-accepted concepts such as the "two-hit hypothesis," and somewhat confusing information regarding polycystin-1 and -2 localization and protein interactions. Special attention is paid to the recently discovered role of the cilium in polycystic kidney disease and the model it suggests. Studying ADPKD is important, not only as an evaluation of a multisystem disorder that spans a lifetime, but as a testament to the achievements of modern biology and medicine.
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Affiliation(s)
- Brendan J Smyth
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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46
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Bersani E, De Fonzo V, Aluffi-Pentini F, Parisi V. On new hypotheses about autosomal dominant polycystic kidney disease type 1. Med Hypotheses 2001; 57:754-8. [PMID: 11918441 DOI: 10.1054/mehy.2001.1482] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The purpose of this paper is to suggest a partial explanation of the aetiology of autosomal dominant polycystic kidney disease type 1, one of the most common genetic diseases in humans. To this aim we put forward a number of interconnected ideas, based on a number of experimental evidences and plausibility arguments. We stress the major role played by the instability of some genomic tandem repeats, together with the DNA structures known as quadruplexes, the pseudogenes and the gene conversion. The model we propose can be considered a multi-hit generalization of the well-known two-hit model, a generalization that could well have a validity also outside the specific context. We finally provide an indication of the likely guilty DNA segment for the above disease, and we propose a possible simple experimental line of action aimed to confirm or disproof our suggestion.
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Affiliation(s)
- E Bersani
- EuroBioPark c/o Parco Scientifico, Università di Roma Tor Vergata, Italy
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48
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Abstract
Autosomal dominant polycystic kidney disease is a common inherited disorder, which is characterised by the formation of fluid-filled cysts in both kidneys that leads to progressive renal failure. Mutations in two genes, PKD1 and PKD2, are associated with the disorder. We describe the various factors that cause variation in disease progression between patients. These include whether the patient has a germline mutation in the PKD1 or in the PKD2 gene, and the nature of the mutation. Detection of mutations in PKD1 is complicated, but the total number identified is rising and will enable genotype-to-phenotype studies. Another factor affecting disease progression is the occurrence of somatic mutations in PKD genes. Furthermore, modifying genes might directly affect the function of polycystins by affecting the rate of somatic mutations or the rate of protein interactions, or they might affect cystogenesis itself or clinical factors associated with disease progression. Finally, environmental factors that speed up or slow down progress towards chronic renal failure have been identified in rodents.
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Affiliation(s)
- D J Peters
- Department of Human and Clinical Genetics, Leiden University Medical Centre, 2333AL, Leiden, Netherlands.
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49
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Abstract
An intriguing feature of autosomal dominant polycystic kidney disease (ADPKD) is the focal and sporadic nature of individual cyst formation. Typically, only a few renal cysts are detectable in an affected individual during the first two decades of life. By the fifth decade, however, hundreds to thousands of renal cysts can be found in most patients. Additionally, significant intra-familial variability of ADPKD has been well documented. Taken together, these findings suggest that factor(s) in addition to the germline mutation of a polycystic kidney disease gene might be required for individual cyst formation. Indeed, recent studies have provided compelling evidence in support of a "two-hit" model of cystogenesis in ADPKD. In this model, inactivation of both copies of a polycystic kidney disease gene by germline and somatic mutations within an epithelial cell provides growth advantages for it to proliferate clonally into a cyst. This article highlights key findings of these recent studies and discusses the controversies and implications of the "two-hit" model in ADPKD.
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Affiliation(s)
- Y Pei
- Divisions of Nephrology and Genomic Medicine Dept of Medicine, University Health Network, Toronto, Ontario, Canada M5G 2C4.
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50
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Pei Y, Paterson AD, Wang KR, He N, Hefferton D, Watnick T, Germino GG, Parfrey P, Somlo S, St George-Hyslop P. Bilineal disease and trans-heterozygotes in autosomal dominant polycystic kidney disease. Am J Hum Genet 2001; 68:355-63. [PMID: 11156533 PMCID: PMC1235269 DOI: 10.1086/318188] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2000] [Accepted: 12/04/2000] [Indexed: 11/04/2022] Open
Abstract
In searching for a putative third gene for autosomal dominant polycystic kidney disease (ADPKD), we studied the genetic inheritance of a large family (NFL10) previously excluded from linkage to both the PKD1 locus and the PKD2 locus. We screened 48 members of the NFL10 pedigree, by ultrasonography, and genotyped them, with informative markers, at both the PKD1 locus and the PKD2 locus. Twenty-eight of 48 individuals assessed were affected with ADPKD. Inspection of the haplotypes of these individuals suggested the possibility of bilineal disease from independently segregating PKD1 and PKD2 mutations. Using single-stranded conformational analysis, we screened for and found a PKD2 mutation (i.e., 2152delA; L736X) in 12 affected pedigree members. Additionally, when the disease status of these individuals was coded as "unknown" in linkage analysis, we also found, with markers at the PKD1 locus, significant LOD scores (i.e., >3.0). These findings strongly support the presence of a PKD1 mutation in 15 other affected pedigree members, who lack the PKD2 mutation. Two additional affected individuals had trans-heterozygous mutations involving both genes, and they had renal disease that was more severe than that in affected individuals who had either mutation alone. This is the first documentation of bilineal disease in ADPKD. In humans, trans-heterozygous mutations involving both PKD1 and PKD2 are not necessarily embryonically lethal. However, the disease associated with the presence of both mutations appears to be more severe than the disease associated with either mutation alone. The presence of bilineal disease as a confounder needs to be considered seriously in the search for the elusive PKD3 locus.
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Affiliation(s)
- Y Pei
- Division of Genomic Medicine, Department of Medicine, University Health Network, Toronto, Ontario, Canada.
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