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Moore SC, Vaz de Castro PAS, Yaqub D, Jose PA, Armando I. Anti-Inflammatory Effects of Peripheral Dopamine. Int J Mol Sci 2023; 24:13816. [PMID: 37762126 PMCID: PMC10530375 DOI: 10.3390/ijms241813816] [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: 05/04/2023] [Revised: 08/18/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023] Open
Abstract
Dopamine is synthesized in the nervous system where it acts as a neurotransmitter. Dopamine is also synthesized in a number of peripheral organs as well as in several types of cells and has organ-specific functions and, as demonstrated more recently, is involved in the regulation of the immune response and inflammatory reaction. In particular, the renal dopaminergic system is very important in the regulation of sodium transport and blood pressure and is particularly sensitive to stimuli that cause oxidative stress and inflammation. This review is focused on how dopamine is synthesized in organs and tissues and the mechanisms by which dopamine and its receptors exert their effects on the inflammatory response.
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Affiliation(s)
| | | | | | | | - Ines Armando
- Division of Kidney Diseases and Hypertension, Department of Medicine, The George Washington School of Medicine and Health Sciences, Washington, DC 20037, USA; (S.C.M.); (P.A.S.V.d.C.); (D.Y.); (P.A.J.)
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2
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Garrett MR, Korstanje R. Using Genetic and Species Diversity to Tackle Kidney Disease. Trends Genet 2020; 36:499-509. [PMID: 32362446 DOI: 10.1016/j.tig.2020.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/26/2020] [Accepted: 04/03/2020] [Indexed: 12/18/2022]
Abstract
Progress in the identification of causal genes and understanding of the mechanism underlying kidney disease is hindered by the almost exclusive use of a few animal models with restrictive monogenic backgrounds that may be more resistant to kidney disease compared with humans and, therefore, poor models. Exploring the large genetic diversity in classical animal models, such as mice and rats, and leveraging species diversity will allow us to use the genetic advantages of zebrafish, Drosophila, and other species, to develop both new animal models that are more relevant to the study of human kidney disease and potential therapies.
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Affiliation(s)
- Michael R Garrett
- Department of Pharmacology, University of Mississippi Medical Center, Jackson, MS, USA; Department of Medicine (Nephrology), University of Mississippi Medical Center, Jackson, MS, USA; Department of Pediatrics (Genetics), University of Mississippi Medical Center, Jackson, MS, USA
| | - Ron Korstanje
- The Jackson Laboratory for Mammalian Genetics, Bar Harbor, Maine, ME, USA; Mount Desert Island Biological Laboratory, Bar Harbor, Maine, ME, USA.
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3
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Qiu C, Huang S, Park J, Park Y, Ko YA, Seasock MJ, Bryer JS, Xu XX, Song WC, Palmer M, Hill J, Guarnieri P, Hawkins J, Boustany-Kari CM, Pullen SS, Brown CD, Susztak K. Renal compartment-specific genetic variation analyses identify new pathways in chronic kidney disease. Nat Med 2018; 24:1721-1731. [PMID: 30275566 PMCID: PMC6301011 DOI: 10.1038/s41591-018-0194-4] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 08/08/2018] [Indexed: 12/11/2022]
Abstract
Chronic kidney disease (CKD), a condition in which the kidneys are unable to clear waste products, affects 700 million people globally. Genome-wide association studies (GWASs) have identified sequence variants for CKD; however, the biological basis of these GWAS results remains poorly understood. To address this issue, we created an expression quantitative trait loci (eQTL) atlas for the glomerular and tubular compartments of the human kidney. Through integrating the CKD GWAS with eQTL, single-cell RNA sequencing and regulatory region maps, we identified novel genes for CKD. Putative causal genes were enriched for proximal tubule expression and endolysosomal function, where DAB2, an adaptor protein in the TGF-β pathway, formed a central node. Functional experiments confirmed that reducing Dab2 expression in renal tubules protected mice from CKD. In conclusion, compartment-specific eQTL analysis is an important avenue for the identification of novel genes and cellular pathways involved in CKD development and thus potential new opportunities for its treatment.
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Affiliation(s)
- Chengxiang Qiu
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, PA, USA
| | - Shizheng Huang
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, PA, USA
| | - Jihwan Park
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, PA, USA
| | - YoSon Park
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Yi-An Ko
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, PA, USA
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Matthew J Seasock
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, PA, USA
| | - Joshua S Bryer
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, PA, USA
| | - Xiang-Xi Xu
- Department of Cell Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Wen-Chao Song
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine at University of Pennsylvania, Pennsylvania, PA, USA
| | - Matthew Palmer
- Pathology and Laboratory Medicine at the Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Jon Hill
- Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, USA
| | - Paolo Guarnieri
- Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, USA
| | - Julie Hawkins
- Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, USA
| | | | - Steven S Pullen
- Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, USA
| | - Christopher D Brown
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Katalin Susztak
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, PA, USA.
- Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA.
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4
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Hao XQ, Huang CF, Liang F, Deng W, Ou YH, Zhang X, Ding L, Wang D, Wang ST. Dopamine Pretreatment Protects Offspring Rats from LPS-Induced Hypertension and Kidney Damage by Inhibiting NLRP3 Activation in Kidney. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2018. [DOI: 10.1134/s1068162018010077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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Konkalmatt PR, Asico LD, Zhang Y, Yang Y, Drachenberg C, Zheng X, Han F, Jose PA, Armando I. Renal rescue of dopamine D2 receptor function reverses renal injury and high blood pressure. JCI Insight 2016; 1. [PMID: 27358912 DOI: 10.1172/jci.insight.85888] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Dopamine D2 receptor (DRD2) deficiency increases renal inflammation and blood pressure in mice. We show here that long-term renal-selective silencing of Drd2 using siRNA increases renal expression of proinflammatory and profibrotic factors and blood pressure in mice. To determine the effects of renal-selective rescue of Drd2 expression in mice, the renal expression of DRD2 was first silenced using siRNA and 14 days later rescued by retrograde renal infusion of adeno-associated virus (AAV) vector with DRD2. Renal Drd2 siRNA treatment decreased the renal expression of DRD2 protein by 55%, and DRD2 AAV treatment increased the renal expression of DRD2 protein by 7.5- to 10-fold. Renal-selective DRD2 rescue reduced the expression of proinflammatory factors and kidney injury, preserved renal function, and normalized systolic and diastolic blood pressure. These results demonstrate that the deleterious effects of renal-selective Drd2 silencing on renal function and blood pressure were rescued by renal-selective overexpression of DRD2. Moreover, the deleterious effects of 45-minute bilateral ischemia/reperfusion on renal function and blood pressure in mice were ameliorated by a renal-selective increase in DRD2 expression by the retrograde ureteral infusion of DRD2 AAV immediately after the induction of ischemia/reperfusion injury. Thus, 14 days after ischemia/reperfusion injury, the renal expression of profibrotic factors, serum creatinine, and blood pressure were lower in mice infused with DRD2 AAV than in those infused with control AAV. These results indicate an important role of renal DRD2 in limiting renal injury and preserving normal renal function and blood pressure.
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Affiliation(s)
- Prasad R Konkalmatt
- Department of Medicine, The George Washington University, Washington, DC, USA, and Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Laureano D Asico
- Department of Medicine, The George Washington University, Washington, DC, USA, and Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Yanrong Zhang
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Yu Yang
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Cinthia Drachenberg
- Department of Pathology, University of Maryland Medical Center, Baltimore, Maryland, USA
| | - Xiaoxu Zheng
- Department of Medicine, The George Washington University, Washington, DC, USA, and Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Fei Han
- Kidney Disease Center, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Pedro A Jose
- Department of Medicine, The George Washington University, Washington, DC, USA, and Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA; Department of Physiology, The George Washington University, Washington, DC, USA, and University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Ines Armando
- Department of Medicine, The George Washington University, Washington, DC, USA, and Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
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6
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Abstract
Several studies show evidence for the genetic basis of renal disease, which renders some individuals more prone than others to accelerated renal aging. Studying the genetics of renal aging can help us to identify genes involved in this process and to unravel the underlying pathways. First, this opinion article will give an overview of the phenotypes that can be observed in age-related kidney disease. Accurate phenotyping is essential in performing genetic analysis. For kidney aging, this could include both functional and structural changes. Subsequently, this article reviews the studies that report on candidate genes associated with renal aging in humans and mice. Several loci or candidate genes have been found associated with kidney disease, but identification of the specific genetic variants involved has proven to be difficult. CUBN, UMOD, and SHROOM3 were identified by human GWAS as being associated with albuminuria, kidney function, and chronic kidney disease (CKD). These are promising examples of genes that could be involved in renal aging, and were further mechanistically evaluated in animal models. Eventually, we will provide approaches for performing genetic analysis. We should leverage the power of mouse models, as testing in humans is limited. Mouse and other animal models can be used to explain the underlying biological mechanisms of genes and loci identified by human GWAS. Furthermore, mouse models can be used to identify genetic variants associated with age-associated histological changes, of which Far2, Wisp2, and Esrrg are examples. A new outbred mouse population with high genetic diversity will facilitate the identification of genes associated with renal aging by enabling high-resolution genetic mapping while also allowing the control of environmental factors, and by enabling access to renal tissues at specific time points for histology, proteomics, and gene expression.
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Affiliation(s)
- Gerda A. Noordmans
- Department of Pathology and Medical Biology University of Groningen University Medical Center Groningen Groningen the Netherlands
| | - Jan‐Luuk Hillebrands
- Department of Pathology and Medical Biology University of Groningen University Medical Center Groningen Groningen the Netherlands
| | - Harry Goor
- Department of Pathology and Medical Biology University of Groningen University Medical Center Groningen Groningen the Netherlands
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7
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Han F, Konkalmatt P, Chen J, Gildea J, Felder RA, Jose PA, Armando I. MiR-217 mediates the protective effects of the dopamine D2 receptor on fibrosis in human renal proximal tubule cells. Hypertension 2015; 65:1118-25. [PMID: 25801876 DOI: 10.1161/hypertensionaha.114.05096] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 03/01/2015] [Indexed: 01/11/2023]
Abstract
Lack or downregulation of the dopamine D2 receptor (D2R) increases the vulnerability to renal inflammation independent of blood pressure in mice. Common single nucleotide polymorphisms (SNPs) rs6276, 6277, and 1800497 in the human D2R gene are associated with decreased receptor expression/function and hypertension. Human renal proximal tubule cells from subjects carrying these SNPs have decreased D2R expression and increased expression of profibrotic factors and production of extracellular matrix proteins. We tested the hypothesis that the D2R mediates these effects by regulating micro-RNA expression. In cells carrying D2R SNPs, micro-RNAs (miRs)-217, miR-224, miR-335, and miR-1265 were downregulated, whereas miR-1290 was upregulated >4-fold compared with those carrying D2R wild-type alleles. However, only miR-217 was directly regulated by D2R expression. In cells carrying D2R wild-type, miR-217 inhibitor increased the expression of transforming growth factor (TGF)-β1, matrix metalloproteinase 3, fibronectin 1, and collagen 1a, whereas miR-217 mimic had the opposite effect. In cells carrying D2R SNPs, miR-217 mimic also decreased the expression of TGFβ1 and its targets. Wnt5a, a miR-217 target, was increased in cells carrying D2R SNPs and decreased by miR-217 mimic but increased by miR-217 inhibitor in both cell types. In cells carrying D2R wild-type, Wnt5a treatment increased TGFβ1 while silencing Ror2, a Wnt5a receptor, decreased TGFβ1 and blunted the Wnt5a-induced increase in cells carrying D2R wild-type. Our results show that renal proximal tubule cells from subjects carrying D2R SNPs resulting in D2R downregulation have increased TGFβ1 that is mediated by decreased regulation of the miR-217-Wnt5a-Ror2 pathway.
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Affiliation(s)
- Fei Han
- From the Kidney Disease Center, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China (F.H., J.C.); Division of Nephrology, Department of Medicine (P.K., P.A.J., I.A.) and Department of Physiology (P.A.J.), University of Maryland School of Medicine, Baltimore; and Department of Pathology, University of Virginia School of Medicine, Charlottesville (J.G., R.A.F.)
| | - Prasad Konkalmatt
- From the Kidney Disease Center, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China (F.H., J.C.); Division of Nephrology, Department of Medicine (P.K., P.A.J., I.A.) and Department of Physiology (P.A.J.), University of Maryland School of Medicine, Baltimore; and Department of Pathology, University of Virginia School of Medicine, Charlottesville (J.G., R.A.F.)
| | - Jianghua Chen
- From the Kidney Disease Center, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China (F.H., J.C.); Division of Nephrology, Department of Medicine (P.K., P.A.J., I.A.) and Department of Physiology (P.A.J.), University of Maryland School of Medicine, Baltimore; and Department of Pathology, University of Virginia School of Medicine, Charlottesville (J.G., R.A.F.)
| | - John Gildea
- From the Kidney Disease Center, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China (F.H., J.C.); Division of Nephrology, Department of Medicine (P.K., P.A.J., I.A.) and Department of Physiology (P.A.J.), University of Maryland School of Medicine, Baltimore; and Department of Pathology, University of Virginia School of Medicine, Charlottesville (J.G., R.A.F.)
| | - Robin A Felder
- From the Kidney Disease Center, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China (F.H., J.C.); Division of Nephrology, Department of Medicine (P.K., P.A.J., I.A.) and Department of Physiology (P.A.J.), University of Maryland School of Medicine, Baltimore; and Department of Pathology, University of Virginia School of Medicine, Charlottesville (J.G., R.A.F.)
| | - Pedro A Jose
- From the Kidney Disease Center, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China (F.H., J.C.); Division of Nephrology, Department of Medicine (P.K., P.A.J., I.A.) and Department of Physiology (P.A.J.), University of Maryland School of Medicine, Baltimore; and Department of Pathology, University of Virginia School of Medicine, Charlottesville (J.G., R.A.F.)
| | - Ines Armando
- From the Kidney Disease Center, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China (F.H., J.C.); Division of Nephrology, Department of Medicine (P.K., P.A.J., I.A.) and Department of Physiology (P.A.J.), University of Maryland School of Medicine, Baltimore; and Department of Pathology, University of Virginia School of Medicine, Charlottesville (J.G., R.A.F.)
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8
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Lazzeri E, Ronconi E, Angelotti ML, Peired A, Mazzinghi B, Becherucci F, Conti S, Sansavini G, Sisti A, Ravaglia F, Lombardi D, Provenzano A, Manonelles A, Cruzado JM, Giglio S, Roperto RM, Materassi M, Lasagni L, Romagnani P. Human Urine-Derived Renal Progenitors for Personalized Modeling of Genetic Kidney Disorders. J Am Soc Nephrol 2015; 26:1961-74. [PMID: 25568173 DOI: 10.1681/asn.2014010057] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 09/30/2014] [Indexed: 12/16/2022] Open
Abstract
The critical role of genetic and epigenetic factors in the pathogenesis of kidney disorders is gradually becoming clear, and the need for disease models that recapitulate human kidney disorders in a personalized manner is paramount. In this study, we describe a method to select and amplify renal progenitor cultures from the urine of patients with kidney disorders. Urine-derived human renal progenitors exhibited phenotype and functional properties identical to those purified from kidney tissue, including the capacity to differentiate into tubular cells and podocytes, as demonstrated by confocal microscopy, Western blot analysis of podocyte-specific proteins, and scanning electron microscopy. Lineage tracing studies performed with conditional transgenic mice, in which podocytes are irreversibly tagged upon tamoxifen treatment (NPHS2.iCreER;mT/mG), that were subjected to doxorubicin nephropathy demonstrated that renal progenitors are the only urinary cell population that can be amplified in long-term culture. To validate the use of these cells for personalized modeling of kidney disorders, renal progenitors were obtained from (1) the urine of children with nephrotic syndrome and carrying potentially pathogenic mutations in genes encoding for podocyte proteins and (2) the urine of children without genetic alterations, as validated by next-generation sequencing. Renal progenitors obtained from patients carrying pathogenic mutations generated podocytes that exhibited an abnormal cytoskeleton structure and functional abnormalities compared with those obtained from patients with proteinuria but without genetic mutations. The results of this study demonstrate that urine-derived patient-specific renal progenitor cultures may be an innovative research tool for modeling of genetic kidney disorders.
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Affiliation(s)
- Elena Lazzeri
- Excellence Centre for Research, Transfer and High Education for the Development of DE NOVO Therapies (DENOTHE) and
| | - Elisa Ronconi
- Excellence Centre for Research, Transfer and High Education for the Development of DE NOVO Therapies (DENOTHE) and Department of Clinical and Experimental Biomedical Sciences, University of Florence, Florence, Italy
| | - Maria Lucia Angelotti
- Excellence Centre for Research, Transfer and High Education for the Development of DE NOVO Therapies (DENOTHE) and
| | - Anna Peired
- Excellence Centre for Research, Transfer and High Education for the Development of DE NOVO Therapies (DENOTHE) and Department of Clinical and Experimental Biomedical Sciences, University of Florence, Florence, Italy
| | | | - Francesca Becherucci
- Pediatric Nephrology Unit, Meyer Children's University Hospital, Florence, Italy
| | - Sara Conti
- IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri," Centro Anna Maria Astori, Bergamo, Italy; and
| | - Giulia Sansavini
- Pediatric Nephrology Unit, Meyer Children's University Hospital, Florence, Italy
| | - Alessandro Sisti
- Excellence Centre for Research, Transfer and High Education for the Development of DE NOVO Therapies (DENOTHE) and
| | - Fiammetta Ravaglia
- Pediatric Nephrology Unit, Meyer Children's University Hospital, Florence, Italy
| | - Duccio Lombardi
- Excellence Centre for Research, Transfer and High Education for the Development of DE NOVO Therapies (DENOTHE) and
| | | | - Anna Manonelles
- Department of Nephrology, Bellvitge's University Hospital, Barcelona, Spain
| | - Josep M Cruzado
- Department of Nephrology, Bellvitge's University Hospital, Barcelona, Spain
| | - Sabrina Giglio
- Department of Clinical and Experimental Biomedical Sciences, University of Florence, Florence, Italy; Medical Genetics Unit and
| | - Rosa Maria Roperto
- Pediatric Nephrology Unit, Meyer Children's University Hospital, Florence, Italy
| | - Marco Materassi
- Pediatric Nephrology Unit, Meyer Children's University Hospital, Florence, Italy
| | - Laura Lasagni
- Excellence Centre for Research, Transfer and High Education for the Development of DE NOVO Therapies (DENOTHE) and
| | - Paola Romagnani
- Excellence Centre for Research, Transfer and High Education for the Development of DE NOVO Therapies (DENOTHE) and Department of Clinical and Experimental Biomedical Sciences, University of Florence, Florence, Italy; Pediatric Nephrology Unit, Meyer Children's University Hospital, Florence, Italy;
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9
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Gopalakrishnan K, Kumarasamy S, Mell B, Joe B. Genome-wide identification of long noncoding RNAs in rat models of cardiovascular and renal disease. Hypertension 2014; 65:200-10. [PMID: 25385761 DOI: 10.1161/hypertensionaha.114.04498] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Long noncoding RNAs (lncRNAs) are an emerging class of genomic regulatory molecules reported in various species. In the rat, which is one of the major mammalian model organisms, discovery of lncRNAs on a genome-wide scale is lagging. Renal lncRNA sequencing and lncRNA transcriptome analysis were conducted in 3 rat strains that are widely used in cardiovascular and renal research: the Dahl salt-sensitive rat, the spontaneously hypertensive rat, and the Dahl salt-resistant rat. Through the RNA sequencing approach, 3273 transcripts were identified as rat lncRNAs. A majority of lncRNAs were without predicted target genes. Differential expression of 273 and 749 lncRNAs was detected between Dahl salt-sensitive versus Dahl salt-resistant and Dahl salt-sensitive versus spontaneously hypertensive rat comparisons, respectively. To couple the observed differential expression of lncRNAs with the status of mRNAs, an mRNA transcriptome analysis was conducted. Several cis mRNA genes were coregulated with lncRNAs. Of these, the protein expression status of 4 target genes, Asb3, Chac2, Pex11b, and Sp5, were differentially expressed between the relevant strain comparisons, thereby suggesting that the differentially expressed lncRNAs associated with these genes are candidate genetic determinants of blood pressure. This study serves as a first-generation catalog of rat lncRNAs and illustrates the prioritization of lncRNAs as candidates for complex polygenic traits.
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Affiliation(s)
- Kathirvel Gopalakrishnan
- From the Program in Physiological Genomics, Center for Hypertension and Personalized Medicine, Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, OH
| | - Sivarajan Kumarasamy
- From the Program in Physiological Genomics, Center for Hypertension and Personalized Medicine, Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, OH
| | - Blair Mell
- From the Program in Physiological Genomics, Center for Hypertension and Personalized Medicine, Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, OH
| | - Bina Joe
- From the Program in Physiological Genomics, Center for Hypertension and Personalized Medicine, Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, OH.
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10
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Jiang X, Konkalmatt P, Yang Y, Gildea J, Jones JE, Cuevas S, Felder RA, Jose PA, Armando I. Single-nucleotide polymorphisms of the dopamine D2 receptor increase inflammation and fibrosis in human renal proximal tubule cells. Hypertension 2013; 63:e74-80. [PMID: 24379187 DOI: 10.1161/hypertensionaha.113.02569] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The dopamine D2 receptor (D2R) negatively regulates inflammation in mouse renal proximal tubule cells (RPTCs), and lack or downregulation of the receptor in mice increases the vulnerability to renal inflammation independent of blood pressure. Some common single-nucleotide polymorphisms (SNPs; rs6276, rs6277, and rs1800497) in the human DRD2 gene are associated with decreased D2R expression and function, as well as high blood pressure. We tested the hypothesis that human RPTCs (hRPTCs) expressing these SNPs have increased expression of inflammatory and injury markers. We studied immortalized hRPTCs carrying D2R SNPs and compared them with cells carrying no D2R SNPs. RPTCs with D2R SNPs had decreased D2R expression and function. The expressions of the proinflammatory tumor necrosis factor-α and the profibrotic transforming growth factor-β1 and its signaling targets Smad3 and Snail1 were increased in hRPTC with D2R SNPs. These cells also showed induction of epithelial mesenchymal transition and production of extracellular matrix proteins, assessed by increased vimentin, fibronectin 1, and collagen I a1. To test the specificity of these D2R SNP effects, hRPTC with D2R SNPs were transfected with a plasmid encoding wild-type DRD2. The expression of D2R was increased and that of transforming growth factor-β1, Smad3, Snail1, vimentin, fibronectin 1, and collagen I a1 was decreased in hRPTC with D2R SNPs transfected with wild-type DRD2 compared with hRPTC-D2R SNP transfected with empty vector. These data support the hypothesis that D2R function has protective effects in hRPTCs and suggest that carriers of these SNPs may be prone to chronic renal disease and high blood pressure.
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Affiliation(s)
- Xiaoliang Jiang
- University of Maryland School of Medicine, Department of Medicine, Division of Nephrology, 20 Penn St- HSFII Suite S003C, Baltimore, MD 21201.
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11
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Gardet A, Zheng TS, Viney JL. Genetic architecture of human fibrotic diseases: disease risk and disease progression. Front Pharmacol 2013; 4:159. [PMID: 24391588 PMCID: PMC3866586 DOI: 10.3389/fphar.2013.00159] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 12/03/2013] [Indexed: 12/12/2022] Open
Abstract
Genetic studies of human diseases have identified multiple genetic risk loci for various fibrotic diseases. This has provided insights into the myriad of biological pathways potentially involved in disease pathogenesis. These discoveries suggest that alterations in immune responses, barrier function, metabolism and telomerase activity may be implicated in the genetic risks for fibrotic diseases. In addition to genetic disease-risks, the identification of genetic disease-modifiers associated with disease complications, severity or prognosis provides crucial insights into the biological processes implicated in disease progression. Understanding the biological processes driving disease progression may be critical to delineate more effective strategies for therapeutic interventions. This review provides an overview of current knowledge and gaps regarding genetic disease-risks and genetic disease-modifiers in human fibrotic diseases.
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12
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Martini S, Nair V, Patel SR, Eichinger F, Nelson RG, Weil EJ, Pezzolesi MG, Krolewski AS, Randolph A, Keller BJ, Werner T, Kretzler M. From single nucleotide polymorphism to transcriptional mechanism: a model for FRMD3 in diabetic nephropathy. Diabetes 2013; 62:2605-12. [PMID: 23434934 PMCID: PMC3712052 DOI: 10.2337/db12-1416] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Genome-wide association studies have proven to be highly effective at defining relationships between single nucleotide polymorphisms (SNPs) and clinical phenotypes in complex diseases. Establishing a mechanistic link between a noncoding SNP and the clinical outcome is a significant hurdle in translating associations into biological insight. We demonstrate an approach to assess the functional context of a diabetic nephropathy (DN)-associated SNP located in the promoter region of the gene FRMD3. The approach integrates pathway analyses with transcriptional regulatory pattern-based promoter modeling and allows the identification of a transcriptional framework affected by the DN-associated SNP in the FRMD3 promoter. This framework provides a testable hypothesis for mechanisms of genomic variation and transcriptional regulation in the context of DN. Our model proposes a possible transcriptional link through which the polymorphism in the FRMD3 promoter could influence transcriptional regulation within the bone morphogenetic protein (BMP)-signaling pathway. These findings provide the rationale to interrogate the biological link between FRMD3 and the BMP pathway and serve as an example of functional genomics-based hypothesis generation.
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Affiliation(s)
- Sebastian Martini
- Departments of Internal Medicine and Nephrology, University of Michigan, Ann Arbor, Michigan
| | - Viji Nair
- Departments of Internal Medicine and Nephrology, University of Michigan, Ann Arbor, Michigan
| | - Sanjeevkumar R. Patel
- Departments of Internal Medicine and Nephrology, University of Michigan, Ann Arbor, Michigan
| | - Felix Eichinger
- Departments of Internal Medicine and Nephrology, University of Michigan, Ann Arbor, Michigan
| | - Robert G. Nelson
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona
| | - E. Jennifer Weil
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona
| | - Marcus G. Pezzolesi
- Research and Clinic Divisions, Joslin Diabetes Center, Boston, Massachusetts
| | | | - Ann Randolph
- Departments of Internal Medicine and Nephrology, University of Michigan, Ann Arbor, Michigan
| | - Benjamin J. Keller
- Department of Computer Science, Eastern Michigan University, Ypsilanti, Michigan
| | - Thomas Werner
- Departments of Internal Medicine and Nephrology, University of Michigan, Ann Arbor, Michigan
- Genomatix Software GmbH, Munich, Germany
| | - Matthias Kretzler
- Departments of Internal Medicine and Nephrology, University of Michigan, Ann Arbor, Michigan
- Corresponding author: Matthias Kretzler,
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13
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Long DA, Kolatsi-Joannou M, Price KL, Dessapt-Baradez C, Huang JL, Papakrivopoulou E, Hubank M, Korstanje R, Gnudi L, Woolf AS. Albuminuria is associated with too few glomeruli and too much testosterone. Kidney Int 2013; 83:1118-29. [PMID: 23447063 PMCID: PMC3674403 DOI: 10.1038/ki.2013.45] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 12/15/2012] [Accepted: 12/21/2012] [Indexed: 12/12/2022]
Abstract
Normally, the glomerular filtration barrier almost completely excludes circulating albumin from entering the urine. Genetic variation and both pre- and postnatal environmental factors may affect albuminuria in humans. Here we determine whether glomerular gene expression in mouse strains with naturally occurring variations in albuminuria would allow identification of proteins deregulated in relatively 'leaky' glomeruli. Albuminuria increased in female B6 to male B6 to female FVB/N to male FVB/N mice, whereas the number of glomeruli/kidney was the exact opposite. Testosterone administration led to increased albuminuria in female B6 but not female FVB/N mice. A common set of 39 genes, many expressed in podocytes, were significantly differentially expressed in each of the four comparisons: male versus female B6 mice, male versus female FVB/N mice, male FVB/N versus male B6 mice, and female FVB/N versus female B6 mice. The transcripts encoded proteins involved in oxidation/reduction reactions, ion transport, and enzymes involved in detoxification. These proteins may represent novel biomarkers and even therapeutic targets for early kidney and cardiovascular disease.
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Affiliation(s)
- David A Long
- Nephro-Urology Unit, UCL Institute of Child Health, London, UK.
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14
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Gopalakrishnan K, Kumarasamy S, Yan Y, Liu J, Kalinoski A, Kothandapani A, Farms P, Joe B. Increased Expression of Rififylin in A < 330 Kb Congenic Strain is Linked to Impaired Endosomal Recycling in Proximal Tubules. Front Genet 2012; 3:138. [PMID: 22891072 PMCID: PMC3413941 DOI: 10.3389/fgene.2012.00138] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Accepted: 07/11/2012] [Indexed: 11/13/2022] Open
Abstract
Cell surface proteins are internalized into the cell through endocytosis and either degraded within lysosomes or recycled back to the plasma membrane. While perturbations in endosomal internalization are known to modulate renal function, it is not known whether similar alterations in recycling affect renal function. Rififylin is a known regulator of endocytic recycling with E3 ubiquitin protein ligase activity. In this study, using two genetically similar strains, the Dahl Salt-sensitive rat and an S.LEW congenic strain, which had allelic variants within a < 330 kb segment containing rififylin, we tested the hypothesis that alterations in endosomal recycling affect renal function. The congenic strain had 1.59-fold higher renal expression of rififylin. Transcriptome analysis indicated that components of both endocytosis and recycling were upregulated in the congenic strain. Transcription of Atp1a1 and cell surface content of the protein product of Atp1a1, the alpha subunit of Na+K+ATPase were increased in the proximal tubules from the congenic strain. Because rififylin does not directly regulate endocytosis and it is also a differentially expressed gene within the congenic segment, we reasoned that the observed alterations in the transcriptome of the congenic strain constitute a feedback response to the primary functional alteration of recycling caused by rififylin. To test this, recycling of transferrin was studied in isolated proximal tubules. Recycling was significantly delayed within isolated proximal tubules of the congenic strain, which also had a higher level of polyubiquitinated proteins and proteinuria compared with S. These data provide evidence to suggest that delayed endosomal recycling caused by excess of rififylin indirectly affects endocytosis, enhances intracellular protein polyubiquitination and contributes to proteinuria.
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Affiliation(s)
- Kathirvel Gopalakrishnan
- Center for Hypertension and Personalized Medicine, University of Toledo College of Medicine and Life Sciences Toledo, OH, USA
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15
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Thaisz J, Tsaih SW, Feng M, Philip VM, Zhang Y, Yanas L, Sheehan S, Xu L, Miller DR, Paigen B, Chesler EJ, Churchill GA, Dipetrillo K. Genetic analysis of albuminuria in collaborative cross and multiple mouse intercross populations. Am J Physiol Renal Physiol 2012; 303:F972-81. [PMID: 22859403 DOI: 10.1152/ajprenal.00690.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Albuminuria is an important marker of nephropathy that increases the risk of progressive renal and chronic cardiovascular diseases. The genetic basis of kidney disease is well-established in humans and rodent models, but the causal genes remain to be identified. We applied several genetic strategies to map and refine genetic loci affecting albuminuria in mice and translated the findings to human kidney disease. First, we measured albuminuria in mice from 33 inbred strains, used the data for haplotype association mapping (HAM), and detected 10 genomic regions associated with albuminuria. Second, we performed eight F(2) intercrosses between genetically diverse strains to identify six loci underlying albuminuria, each of which was concordant to kidney disease loci in humans. Third, we used the Oak Ridge National Laboratory incipient Collaborative Cross subpopulation to detect an additional novel quantitative trait loci (QTL) underlying albuminuria. We also performed a ninth intercross, between genetically similar strains, that substantially narrowed an albuminuria QTL on Chromosome 17 to a region containing four known genes. Finally, we measured renal gene expression in inbred mice to detect pathways highly correlated with albuminuria. Expression analysis also identified Glcci1, a gene known to affect podocyte structure and function in zebrafish, as a strong candidate gene for the albuminuria QTL on Chromosome 6. Overall, these findings greatly enhance our understanding of the genetic basis of albuminuria in mice and may guide future studies into the genetic basis of kidney disease in humans.
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Affiliation(s)
- Jill Thaisz
- Novartis Institute for BioMedical Research, 1 Health Plaza, Bldg. 437, Rm. 4331, East Hanover, NJ 07936, USA
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16
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Yuan R, Flurkey K, Meng Q, Astle MC, Harrison DE. Genetic regulation of life span, metabolism, and body weight in Pohn, a new wild-derived mouse strain. J Gerontol A Biol Sci Med Sci 2012; 68:27-35. [PMID: 22570136 DOI: 10.1093/gerona/gls104] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Quantitative trait loci (QTL) of longevity identified in human and mouse are significantly colocalized, suggesting that common mechanisms are involved. However, the limited number of strains that have been used in mouse longevity studies undermines the ability to identify longevity genes. We crossed C57BL/6J mice with a new wild-derived strain, Pohn, and identified two life span QTL-Ls1 and Ls2. Interestingly, homologous human longevity QTL colocalize with Ls1. We also defined new QTL for metabolic heat production and body weight. Both phenotypes are significantly correlated with life span. We found that large clone ratio, an in vitro indicator for cellular senescence, is not correlated with life span, suggesting that cell senescence and intrinsic aging are not always associated. Overall, by using Pohn mice, we identified new QTL for longevity-related traits, thus facilitating the exploration of the genetic regulation of aging.
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Affiliation(s)
- Rong Yuan
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
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17
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Yuan R, Peters LL, Paigen B. Mice as a mammalian model for research on the genetics of aging. ILAR J 2011; 52:4-15. [PMID: 21411853 DOI: 10.1093/ilar.52.1.4] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mice are an ideal mammalian model for studying the genetics of aging: considerable resources are available, the generation time is short, and the environment can be easily controlled, an important consideration when performing mapping studies to identify genes that influence lifespan and age-related diseases. In this review we highlight some salient contributions of the mouse in aging research: lifespan intervention studies in the Interventions Testing Program of the National Institute on Aging; identification of the genetic underpinnings of the effects of calorie restriction on lifespan; the Aging Phenome Project at the Jackson Laboratory, which has submitted multiple large, freely available phenotyping datasets to the Mouse Phenome Database; insights from spontaneous and engineered mouse mutants; and complex traits analyses identifying quantitative trait loci that affect lifespan. We also show that genomewide association peaks for lifespan in humans and lifespan quantitative loci for mice map to homologous locations in the genome. Thus, the vast bioinformatic and genetic resources of the mouse can be used to screen candidate genes identified in both mouse and human mapping studies, followed by functional testing, often not possible in humans, to determine their influence on aging.
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Affiliation(s)
- Rong Yuan
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA
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18
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Harris RC. Identification of a Major Chronic Renal Failure Susceptibility Locus in Mice: Perhaps EGFR Determines What Happens to eGFR. J Am Soc Nephrol 2011; 22:201-3. [DOI: 10.1681/asn.2010121290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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19
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Laouari D, Burtin M, Phelep A, Martino C, Pillebout E, Montagutelli X, Friedlander G, Terzi F. TGF-alpha mediates genetic susceptibility to chronic kidney disease. J Am Soc Nephrol 2010; 22:327-35. [PMID: 21183591 DOI: 10.1681/asn.2010040356] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The mechanisms of progression of chronic kidney disease (CKD) are poorly understood. Epidemiologic studies suggest a strong genetic component, but the genes that contribute to the onset and progression of CKD are largely unknown. Here, we applied an experimental model of CKD (75% excision of total renal mass) to six different strains of mice and found that only the FVB/N strain developed renal lesions. We performed a genome-scan analysis in mice generated by back-crossing resistant and sensitive strains; we identified a major susceptibility locus (Ckdp1) on chromosome 6, which corresponds to regions on human chromosome 2 and 3 that link with CKD progression. In silico analysis revealed that the locus includes the gene encoding the EGF receptor (EGFR) ligand TGF-α. TGF-α protein levels markedly increased after nephron reduction exclusively in FVB/N mice, and this increase preceded the development of renal lesions. Furthermore, pharmacologic inhibition of EGFR prevented the development of renal lesions in the sensitive FVB/N strain. These data suggest that variable TGF-α expression may explain, in part, the genetic susceptibility to CKD progression. EGFR inhibition may be a therapeutic strategy to counteract the genetic predisposition to CKD.
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Affiliation(s)
- Denise Laouari
- INSERM U845, Université Paris Descartes, Team: Mechanisms and therapeutic strategies in chronic nephropathies, Hôpital Necker Enfants Malades, Tour Lavoisier, 6ème étage, 149 Rue de Sèvres, 75015 Paris, France
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20
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Hageman RS, Leduc MS, Caputo CR, Tsaih SW, Churchill GA, Korstanje R. Uncovering genes and regulatory pathways related to urinary albumin excretion. J Am Soc Nephrol 2010; 22:73-81. [PMID: 21030601 DOI: 10.1681/asn.2010050561] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Identifying the genes underlying quantitative trait loci (QTL) for disease is difficult, mainly because of the low resolution of the approach and the complex genetics involved. However, recent advances in bioinformatics and the availability of genetic resources now make it possible to narrow the genetic intervals, test candidate genes, and define pathways affected by these QTL. In this study, we mapped three significant QTL and one suggestive QTL for an increased albumin-to-creatinine ratio on chromosomes (Chrs) 1, 4, 15, and 17, respectively, in a cross between the inbred MRL/MpJ and SM/J strains of mice. By combining data from several sources and by utilizing gene expression data, we identified Tlr12 as a likely candidate for the Chr 4 QTL. Through the mapping of 33,881 transcripts measured by microarray on kidney RNA from each of the 173 male F2 animals, we identified several downstream pathways associated with these QTL, including the glycan degradation, leukocyte migration, and antigen-presenting pathways. We demonstrate that by combining data from multiple sources, we can identify not only genes that are likely to be causal candidates for QTL but also the pathways through which these genes act to alter phenotypes. This combined approach provides valuable insights into the causes and consequences of renal disease.
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21
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Abstract
A substantial genetic contribution underlies variation in baseline peripheral blood counts. We performed quantitative trait locus/loci analyses to identify chromosome regions harboring genes influencing red cell hemoglobin concentration using the cell hemoglobin concentration mean (CHCM), a directly measured parameter analogous to the mean cell hemoglobin concentration. Fourteen significant loci (gene symbols Chcmq1-Chcmq14) were detected. Seven of these influenced CHCM in a sex-specific fashion, and 2 showed significant interactive effects (epistasis). For quantitative trait locus/loci detected in multiple crosses, confidence intervals were narrowed using statistical and bioinformatic approaches. Two strong candidate genes emerged and were further analyzed: adult β-globin (Hbb) for Chcmq3 on Chr 7, and transferrin (Trf) for Chcmq2 on Chr 9. High and low allele parental strains in crosses detecting Chcmq3 segregate 100% with the known ancestral haplotype blocks, hemoglobin (Hb) diffuse (Hbb(d)) and Hb single (Hbb(s)), respectively. Hbb(d) consists of nonidentical major and minor polypeptides and exhibits an increased positive charge relative to Hbb(s) due to the net loss of 2 negative residues in the Hbb(dminor) polypeptide, resulting in a pI of 7.85 versus 7.13. Thus, as shown in human erythrocytes, positively charged Hbs are associated with cell dehydration and increased CHCM in mouse erythrocytes.
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22
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Combining QTL data for HDL cholesterol levels from two different species leads to smaller confidence intervals. Heredity (Edinb) 2010; 105:426-32. [PMID: 20551980 PMCID: PMC2958246 DOI: 10.1038/hdy.2010.75] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Quantitative trait locus (QTL) analysis detects regions of a genome that are linked to a complex trait. Once a QTL is detected, the region is narrowed by positional cloning in the hope of determining the underlying candidate gene-methods used include creating congenic strains, comparative genomics and gene expression analysis. Combined cross analysis may also be used for species such as the mouse, if the QTL is detected in multiple crosses. This process involves the recoding of QTL data on a per-chromosome basis, with the genotype recoded on the basis of high- and low-allele status. The data are then combined and analyzed; a successful analysis results in a narrowed and more significant QTL. Using parallel methods, we show that it is possible to narrow a QTL by combining data from two different species, the rat and the mouse. We combined standardized high-density lipoprotein phenotype values and genotype data for the rat and mouse using information from one rat cross and two mouse crosses. We successfully combined data within homologous regions from rat Chr 6 onto mouse Chr 12, and from rat Chr 10 onto mouse Chr 11. The combinations and analyses resulted in QTL with smaller confidence intervals and increased logarithm of the odds ratio scores. The numbers of candidate genes encompassed by the QTL on mouse Chr 11 and 12 were reduced from 1343 to 761 genes and from 613 to 304 genes, respectively. This is the first time that QTL data from different species were successfully combined; this method promises to be a useful tool for narrowing QTL intervals.
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