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Takeuchi F, Liang YQ, Isono M, Tajima M, Cui ZH, Iizuka Y, Gotoda T, Nabika T, Kato N. Integrative genomic analysis of blood pressure and related phenotypes in rats. Dis Model Mech 2021; 14:dmm048090. [PMID: 34010951 PMCID: PMC8188887 DOI: 10.1242/dmm.048090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 03/23/2021] [Indexed: 12/12/2022] Open
Abstract
Despite remarkable progress made in human genome-wide association studies, there remains a substantial gap between statistical evidence for genetic associations and functional comprehension of the underlying mechanisms governing these associations. As a means of bridging this gap, we performed genomic analysis of blood pressure (BP) and related phenotypes in spontaneously hypertensive rats (SHR) and their substrain, stroke-prone SHR (SHRSP), both of which are unique genetic models of severe hypertension and cardiovascular complications. By integrating whole-genome sequencing, transcriptome profiling, genome-wide linkage scans (maximum n=1415), fine congenic mapping (maximum n=8704), pharmacological intervention and comparative analysis with transcriptome-wide association study (TWAS) datasets, we searched causal genes and causal pathways for the tested traits. The overall results validated the polygenic architecture of elevated BP compared with a non-hypertensive control strain, Wistar Kyoto rats (WKY); e.g. inter-strain BP differences between SHRSP and WKY could be largely explained by an aggregate of BP changes in seven SHRSP-derived consomic strains. We identified 26 potential target genes, including rat homologs of human TWAS loci, for the tested traits. In this study, we re-discovered 18 genes that had previously been determined to contribute to hypertension or cardiovascular phenotypes. Notably, five of these genes belong to the kallikrein-kinin/renin-angiotensin systems (KKS/RAS), in which the most prominent differential expression between hypertensive and non-hypertensive alleles could be detected in rat Klk1 paralogs. In combination with a pharmacological intervention, we provide in vivo experimental evidence supporting the presence of key disease pathways, such as KKS/RAS, in a rat polygenic hypertension model.
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Affiliation(s)
- Fumihiko Takeuchi
- Department of Gene Diagnostics and Therapeutics, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, Japan
| | - Yi-Qiang Liang
- Department of Gene Diagnostics and Therapeutics, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, Japan
| | - Masato Isono
- Department of Gene Diagnostics and Therapeutics, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, Japan
| | - Michiko Tajima
- Department of Gene Diagnostics and Therapeutics, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, Japan
| | - Zong Hu Cui
- Department of Functional Pathology, Shimane University Faculty of Medicine, Izumo 693-0021, Japan
| | - Yoko Iizuka
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Takanari Gotoda
- Department of Metabolism and Biochemistry, Kyorin University Faculty of Medicine, Tokyo 181-8611, Japan
| | - Toru Nabika
- Department of Functional Pathology, Shimane University Faculty of Medicine, Izumo 693-0021, Japan
| | - Norihiro Kato
- Department of Gene Diagnostics and Therapeutics, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, Japan
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Berillo O, Ouerd S, Idris-Khodja N, Rehman A, Richer C, Sinnett D, Kwitek AE, Paradis P, Schiffrin EL. Chromosome 2 Fragment Substitutions in Dahl Salt-Sensitive Rats and RNA Sequencing Identified Enpep and Hs2st1 as Vascular Inflammatory Modulators. Hypertension 2020; 77:178-189. [PMID: 33161775 DOI: 10.1161/hypertensionaha.120.15690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Chromosome 2 introgression from normotensive Brown Norway (BN) rats into hypertensive Dahl salt-sensitive (SS) background (SS-chromosome 2BN/Mcwi; consomic S2B) reduced blood pressure and vascular inflammation under a normal-salt diet (NSD). We hypothesized that BN chromosome 2 contains anti-inflammatory genes that could reduce blood pressure and vascular inflammation in rats fed NSD or high-salt diet (HSD). Four- to 6-week old male SS and congenic rats containing the BN chromosome 2 distal portion (SS.BN-[rs13453786-rs66377062]/Aek; S2Ba) and middle segment (SS.BN-[rs106982173-rs65057186]/Aek; S2Bb) were fed NSD or HSD (4% NaCl) up to age 12 to 13 weeks. Systolic blood pressure determined by telemetry was higher in SS rats fed HSD versus NSD. Systolic blood pressure was lower in both congenic rats than in SS under NSD, but similar under HSD versus SS. Reactive oxygen species generation using dihydroethidium staining, expression of vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1, and immune cell infiltration by immunofluorescence demonstrated that S2Ba rats present less inflammation under NSD and more under HSD versus SS rats. RNA sequencing and reverse transcription-quantitative PCR identified 2 differentially expressed genes encoded within BN chromosome 2 distal portion that could act as regulators of vascular inflammation. These were downregulated glutamyl aminopeptidase (Enpep) that was anti-inflammatory under NSD and upregulated heparan sulfate 2-O-sulfotransferase 1 (Hs2st1) that was proinflammatory under HSD. In conclusion, 2 differentially expressed genes encoded within introgressed BN chromosome 2 distal fragment were identified: Enpep associated with reduced vascular inflammation under NSD, and Hs2st1, associated with increased vascular inflammation under HSD.
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Affiliation(s)
- Olga Berillo
- From the Vascular and Hypertension Research Unit, Lady Davis Institute for Medical Research (O.B., S.O., N.I.-K., A.R., P.P., E.L.S.)
| | - Sofiane Ouerd
- From the Vascular and Hypertension Research Unit, Lady Davis Institute for Medical Research (O.B., S.O., N.I.-K., A.R., P.P., E.L.S.)
| | - Noureddine Idris-Khodja
- From the Vascular and Hypertension Research Unit, Lady Davis Institute for Medical Research (O.B., S.O., N.I.-K., A.R., P.P., E.L.S.)
| | - Asia Rehman
- From the Vascular and Hypertension Research Unit, Lady Davis Institute for Medical Research (O.B., S.O., N.I.-K., A.R., P.P., E.L.S.)
| | - Chantal Richer
- Sainte-Justine University Hospital, Montreal, QC, Canada (C.R., D.S.)
| | - Daniel Sinnett
- Sainte-Justine University Hospital, Montreal, QC, Canada (C.R., D.S.)
| | - Anne E Kwitek
- Department of Physiology, Medical College of Wisconsin, Milwaukee (A.E.K.)
| | - Pierre Paradis
- From the Vascular and Hypertension Research Unit, Lady Davis Institute for Medical Research (O.B., S.O., N.I.-K., A.R., P.P., E.L.S.)
| | - Ernesto L Schiffrin
- Department of Medicine (E.L.S.), Sir Mortimer B. Davis-Jewish General Hospital, McGill University
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Padmanabhan S, Joe B. Towards Precision Medicine for Hypertension: A Review of Genomic, Epigenomic, and Microbiomic Effects on Blood Pressure in Experimental Rat Models and Humans. Physiol Rev 2017; 97:1469-1528. [PMID: 28931564 PMCID: PMC6347103 DOI: 10.1152/physrev.00035.2016] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 04/28/2017] [Accepted: 04/29/2017] [Indexed: 12/11/2022] Open
Abstract
Compelling evidence for the inherited nature of essential hypertension has led to extensive research in rats and humans. Rats have served as the primary model for research on the genetics of hypertension resulting in identification of genomic regions that are causally associated with hypertension. In more recent times, genome-wide studies in humans have also begun to improve our understanding of the inheritance of polygenic forms of hypertension. Based on the chronological progression of research into the genetics of hypertension as the "structural backbone," this review catalogs and discusses the rat and human genetic elements mapped and implicated in blood pressure regulation. Furthermore, the knowledge gained from these genetic studies that provide evidence to suggest that much of the genetic influence on hypertension residing within noncoding elements of our DNA and operating through pervasive epistasis or gene-gene interactions is highlighted. Lastly, perspectives on current thinking that the more complex "triad" of the genome, epigenome, and the microbiome operating to influence the inheritance of hypertension, is documented. Overall, the collective knowledge gained from rats and humans is disappointing in the sense that major hypertension-causing genes as targets for clinical management of essential hypertension may not be a clinical reality. On the other hand, the realization that the polygenic nature of hypertension prevents any single locus from being a relevant clinical target for all humans directs future studies on the genetics of hypertension towards an individualized genomic approach.
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Affiliation(s)
- Sandosh Padmanabhan
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; and Center for Hypertension and Personalized Medicine; Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
| | - Bina Joe
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; and Center for Hypertension and Personalized Medicine; Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
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Keum S, Lee HK, Chu PL, Kan MJ, Huang MN, Gallione CJ, Gunn MD, Lo DC, Marchuk DA. Natural genetic variation of integrin alpha L (Itgal) modulates ischemic brain injury in stroke. PLoS Genet 2013; 9:e1003807. [PMID: 24130503 PMCID: PMC3794904 DOI: 10.1371/journal.pgen.1003807] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 08/05/2013] [Indexed: 11/18/2022] Open
Abstract
During ischemic stroke, occlusion of the cerebrovasculature causes neuronal cell death (infarction), but naturally occurring genetic factors modulating infarction have been difficult to identify in human populations. In a surgically induced mouse model of ischemic stroke, we have previously mapped Civq1 to distal chromosome 7 as a quantitative trait locus determining infarct volume. In this study, genome-wide association mapping using 32 inbred mouse strains and an additional linkage scan for infarct volume confirmed that the size of the infarct is determined by ancestral alleles of the causative gene(s). The genetically isolated Civq1 locus in reciprocal recombinant congenic mice refined the critical interval and demonstrated that infarct size is determined by both vascular (collateral vessel anatomy) and non-vascular (neuroprotection) effects. Through the use of interval-specific SNP haplotype analysis, we further refined the Civq1 locus and identified integrin alpha L (Itgal) as one of the causative genes for Civq1. Itgal is the only gene that exhibits both strain-specific amino acid substitutions and expression differences. Coding SNPs, a 5-bp insertion in exon 30b, and increased mRNA and protein expression of a splice variant of the gene (Itgal-003, ENSMUST00000120857), all segregate with infarct volume. Mice lacking Itgal show increased neuronal cell death in both ex vivo brain slice and in vivo focal cerebral ischemia. Our data demonstrate that sequence variation in Itgal modulates ischemic brain injury, and that infarct volume is determined by both vascular and non-vascular mechanisms.
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Affiliation(s)
- Sehoon Keum
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Han Kyu Lee
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Pei-Lun Chu
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Matthew J. Kan
- Department of Immunology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Min-Nung Huang
- Department of Immunology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Carol J. Gallione
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Michael D. Gunn
- Department of Immunology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Donald C. Lo
- Center for Drug Discovery and Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Douglas A. Marchuk
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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5
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Abstract
Progress in complex trait mapping in mice has been accelerated by the development of new populations suited to high-resolution mapping and by statistical methodologies that control for population structure. When combined with newly acquired catalogs of sequence variation in inbred strains, the genetic architecture of these new populations makes it possible to dissect complex traits down to the level of single variants. These analyses have shown not only that complex traits are caused by multiple contributing loci but also that each locus is likely due to the combined effects of multiple causal DNA variants. In combination with new rapid methods for producing transgenic mice that make it efficient to test candidate genes and variants, these advances significantly enhance the mouse genetics toolbox for dissecting quantitative traits.
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Affiliation(s)
- Richard Mott
- Wellcome Trust Center for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom; ,
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6
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Gonik M, Frank E, Keßler MS, Czamara D, Bunck M, Yen YC, Pütz B, Holsboer F, Bettecken T, Landgraf R, Müller-Myhsok B, Touma C, Czibere L. The endocrine stress response is linked to one specific locus on chromosome 3 in a mouse model based on extremes in trait anxiety. BMC Genomics 2012; 13:579. [PMID: 23114097 PMCID: PMC3557225 DOI: 10.1186/1471-2164-13-579] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Accepted: 10/29/2012] [Indexed: 12/17/2022] Open
Abstract
Background The hypothalamic-pituitary-adrenal (HPA) axis is essential to control physiological stress responses in mammals. Its dysfunction is related to several mental disorders, including anxiety and depression. The aim of this study was to identify genetic loci underlying the endocrine regulation of the HPA axis. Method High (HAB) and low (LAB) anxiety-related behaviour mice were established by selective inbreeding of outbred CD-1 mice to model extremes in trait anxiety. Additionally, HAB vs. LAB mice exhibit comorbid characteristics including a differential corticosterone response upon stress exposure. We crossbred HAB and LAB lines to create F1 and F2 offspring. To identify the contribution of the endocrine phenotypes to the total phenotypic variance, we examined multiple behavioural paradigms together with corticosterone secretion-based phenotypes in F2 mice by principal component analysis. Further, to pinpoint the genomic loci of the quantitative trait of the HPA axis stress response, we conducted genome-wide multipoint oligogenic linkage analyses based on Bayesian Markov chain Monte Carlo approach as well as parametric linkage in three-generation pedigrees, followed by a two-dimensional scan for epistasis and association analysis in freely segregating F2 mice using 267 single-nucleotide polymorphisms (SNPs), which were identified to consistently differ between HAB and LAB mice as genetic markers. Results HPA axis reactivity measurements and behavioural phenotypes were represented by independent principal components and demonstrated no correlation. Based on this finding, we identified one single quantitative trait locus (QTL) on chromosome 3 showing a very strong evidence for linkage (2ln (L-score) > 10, LOD > 23) and significant association (lowest Bonferroni adjusted p < 10-28) to the neuroendocrine stress response. The location of the linkage peak was estimated at 42.3 cM (95% confidence interval: 41.3 - 43.3 cM) and was shown to be in epistasis (p-adjusted < 0.004) with the locus at 35.3 cM on the same chromosome. The QTL harbours genes involved in steroid synthesis and cardiovascular effects. Conclusion The very prominent effect on stress-induced corticosterone secretion of the genomic locus on chromosome 3 and its involvement in epistasis highlights the critical role of this specific locus in the regulation of the HPA axis.
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Affiliation(s)
- Mariya Gonik
- Max Planck Institute of Psychiatry, Munich, Germany
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7
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Yalcin B, Flint J. Association studies in outbred mice in a new era of full-genome sequencing. Mamm Genome 2012; 23:719-26. [PMID: 22847376 PMCID: PMC3463788 DOI: 10.1007/s00335-012-9409-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 06/28/2012] [Indexed: 12/30/2022]
Abstract
Thousands of loci that contribute to quantitative traits in outbred crosses of mice have been reported over the last two decades. In this review we discuss how outbred mouse populations can be used to map and identify the genes and sequence variants that give rise to quantitative variation. We discuss heterogeneous stocks, the diversity outbred, and commercially available outbred populations of mice. All of these populations are descended from a small number of progenitor strains. The availability of the complete sequence of laboratory strains means that in many cases it will be possible to reconstruct the genomes of the outbred animals so that in a genetic association study we can detect the effect of all variants, a situation that has so far eluded studies in completely outbred populations. These resources constitute a major advance and make it possible to progress from a quantitative trait locus to a gene at an unprecedented speed.
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Affiliation(s)
- Binnaz Yalcin
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
- Institute of Genetics and Molecular and Cellular Biology, 67404 Illkirch, France
| | - Jonathan Flint
- Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford, OX3 7BN UK
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8
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Flint J. Mapping quantitative traits and strategies to find quantitative trait genes. Methods 2010; 53:163-74. [PMID: 20643209 PMCID: PMC3036800 DOI: 10.1016/j.ymeth.2010.07.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 07/12/2010] [Indexed: 12/17/2022] Open
Abstract
In 1999 a meeting took place at the Jackson Laboratory, a large mouse research centre in Bar Harbor, Maine, to consider the value of systematically collecting phenotypes on inbred strains of mice (Paigen and Eppig (2000) [1]). The group concluded that cataloguing the extensive phenotypic diversity present among laboratory mice, and in particular providing the research community with data from cohorts of animals, phenotyped according to standardized protocols, was essential if we were to take advantage of the possibilities of mouse genetics. Beginning with the collection of basic physiological, biochemical and behavioral data on nine commonly used inbred strains, the project has expanded so that by the beginning of 2010 data for 178 strains had been collected, with 105 phenotype projects yielding over 2000 different measurements (Bogue et al. (2007) [2].
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Affiliation(s)
- Jonathan Flint
- Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, UK.
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9
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Abstract
We compare and contrast the genetic architecture of quantitative phenotypes in two genetically well-characterized model organisms, the laboratory mouse, Mus musculus, and the fruit fly, Drosophila melanogaster, with that found in our own species from recent successes in genome-wide association studies. We show that the current model of large numbers of loci, each of small effect, is true for all species examined, and that discrepancies can be largely explained by differences in the experimental designs used. We argue that the distribution of effect size of common variants is the same for all phenotypes regardless of species, and we discuss the importance of epistasis, pleiotropy, and gene by environment interactions. Despite substantial advances in mapping quantitative trait loci, the identification of the quantitative trait genes and ultimately the sequence variants has proved more difficult, so that our information on the molecular basis of quantitative variation remains limited. Nevertheless, available data indicate that many variants lie outside genes, presumably in regulatory regions of the genome, where they act by altering gene expression. As yet there are very few instances where homologous quantitative trait loci, or quantitative trait genes, have been identified in multiple species, but the availability of high-resolution mapping data will soon make it possible to test the degree of overlap between species.
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10
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Packard M, Saad Y, Gunning WT, Gupta S, Shapiro J, Garrett MR. Investigating the effect of genetic background on proteinuria and renal injury using two hypertensive strains. Am J Physiol Renal Physiol 2009; 296:F839-46. [PMID: 19176703 PMCID: PMC3973645 DOI: 10.1152/ajprenal.90370.2008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Accepted: 01/21/2009] [Indexed: 12/21/2022] Open
Abstract
An earlier linkage analysis conducted on a population derived from the Dahl salt-sensitive hypertensive (S) and the spontaneously hypertensive rat (SHR) identified 10 genomic regions linked to several renal and/or cardiovascular traits. In particular, loci on rat chromosomes (RNO) 8 and 13 were linked to proteinuria, albuminuria, and renal damage. At both loci, the S allele was associated with increased proteinuria and renal damage. The current study aimed to confirm the linkage analysis and to evaluate the effect of genetic background on the ability of each locus (either RNO8 or RNO13) to exert a phenotypic difference when placed on a genetic background either susceptible (S rat) or resistant (SHR) to the development of renal disease. Congenic strains developed to transfer genomic segments from either RNO8 or RNO13 from the SHR onto the S genetic background [S.SHR(8) or S.SHR(13)] demonstrated significantly reduced proteinuria and improved renal function. Both congenic strains demonstrated significantly reduced glomerular and tubular injury, with renal interstitial fibrosis as the predominant pathological difference compared with the S. In contrast, transfer of RNO8 or RNO13 genomic regions from the S onto the resistant SHR genetic background [SHR.S(8) or SHR.S(13)] yielded no significant difference in proteinuria or glomerular, tubular, or interstitial injury compared with SHR. These findings demonstrate that genetic context plays a significant and important role in the phenotypic expression of genes influencing proteinuria on RNO8 and RNO13.
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Affiliation(s)
- Matthew Packard
- Dept. of Medicine and Kidney Disease Center, Medical College of Wisconsin, 8701 Watertown Plank Rd., HRC 4150, Milwaukee, WI 53226, USA
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11
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Bilusić M, Moreno C, Barreto NE, Tschannen MR, Harris EL, Porteous WK, Thompson CM, Grigor MR, Weder A, Boerwinkle E, Hunt SC, Curb JD, Jacob HJ, Kwitek AE. Genetically hypertensive Brown Norway congenic rat strains suggest intermediate traits underlying genetic hypertension. Croat Med J 2009; 49:586-99. [PMID: 18925692 DOI: 10.3325/cmj.2008.5.586] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
AIM To determine the independent and combined effects of three quantitative trait loci (QTL) for blood pressure in the Genetically Hypertensive (GH/Omr) rat by generating and characterizing single and combined congenic strains that have QTL on rat chromosomes (RNO) 2, 6, and 18 from the GH rat introduced into a hypertension resistant Brown Norway (BN) background. METHODS Linkage analysis and QTL identification (genome wide QTL scan) were performed with MapMaker/EXP to build the genetic maps and MapMaker/QTL for linking the phenotypes to the genetic map. The congenic strains were derived using marker-assisted selection strategy from a single male F1 offspring of an intercross between the male GH/Omr and female BN/Elh, followed by 10 generations of selective backcrossing to the female BN progenitor strain. Single congenic strains generated were BN.GH-(D2Rat22-D2Mgh11)/Mcwi (BN.GH2); BN.GH-(D6Mit12-D6Rat15)/Mcwi (BN.GH6); and BN.GH-(D18Rat41-D18Mgh4)/Mcwi (BN.GH18). Blood pressure measurements were obtained either via a catheter placed in the femoral artery or by radiotelemetry. Responses to angiotensin II (ANGII), norepinephrine (NE), and baroreceptor sensitivity were measured in the single congenics. RESULTS Transferring one or more QTL from the hypertensive GH into normotensive BN strain was not sufficient to cause hypertension in any of the developed congenic strains. There were no differences between the parental and congenic strains in their response to NE. However, BN.GH18 rats revealed significantly lower baroreceptor sensitivity (beta=-1.25-/+0.17), whereas BN.GH2 (beta=0.66-/+0.09) and BN.GH18 (beta=0.71-/+0.07) had significantly decreased responses to ANGII from those observed in the BN (beta=0.88-/+0.08). CONCLUSION The failure to alter blood pressure levels by introducing the hypertensive QTL from the GH into the hypertension resistant BN background suggests that the QTL effects are genome background-dependent in the GH rat. BN.GH2 and BN.GH18 rats reveal significant differences in response to ANGII and impaired baroreflex sensitivity, suggesting that we may have captured a locus responsible for the genetic control of baroreceptor sensitivity, which would be considered an intermediate phenotype of blood pressure.
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Affiliation(s)
- Marijo Bilusić
- Trinitas Hospital, Department of Internal Medicine, Seton Hall University, Elizabeth, NJ, USA
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12
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Aneas I, Rodrigues MV, Pauletti BA, Silva GJJ, Carmona R, Cardoso L, Kwitek AE, Jacob HJ, Soler JMP, Krieger JE. Congenic strains provide evidence that four mapped loci in chromosomes 2, 4, and 16 influence hypertension in the SHR. Physiol Genomics 2009; 37:52-7. [PMID: 19126752 DOI: 10.1152/physiolgenomics.90299.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To dissect the genetic architecture controlling blood pressure (BP) regulation in the spontaneously hypertensive rat (SHR) we derived congenic rat strains for four previously mapped BP quantitative trait loci (QTLs) in chromosomes 2, 4, and 16. Target chromosomal regions from the Brown Norway rat (BN) averaging 13-29 cM were introgressed by marker-assisted breeding onto the SHR genome in 12 or 13 generations. Under normal salt intake, QTLs on chromosomes 2a, 2c, and 4 were associated with significant changes in systolic BP (13, 20, and 15 mmHg, respectively), whereas the QTL on chromosome 16 had no measurable effect. On high salt intake (1% NaCl in drinking water for 2 wk), the chromosome 16 QTL had a marked impact on SBP, as did the QTLs on chromosome 2a and 2c (18, 17, and 19 mmHg, respectively), but not the QTL on chromosome 4. Thus these four QTLs affected BP phenotypes differently: 1) in the presence of high salt intake (chromosome 16), 2) only associated with normal salt intake (chromosome 4), and 3) regardless of salt intake (chromosome 2c and 2a). Moreover, salt sensitivity was abrogated in congenics SHR.BN2a and SHR.BN16. Finally, we provide evidence for the influence of genetic background on the expression of the mapped QTLs individually or as a group. Collectively, these data reveal previously unsuspected nuances of the physiological roles of each of the four mapped BP QTLs in the SHR under basal and/or salt loading conditions unforeseen by the analysis of the F2 cross.
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Affiliation(s)
- Ivy Aneas
- Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil
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Sedlacek K, Stark K, Cunha SR, Pfeufer A, Weber S, Berger I, Perz S, Kääb S, Wichmann HE, Mohler PJ, Hengstenberg C, Jeron A. Common Genetic Variants in
ANK2
Modulate QT Interval. ACTA ACUST UNITED AC 2008; 1:93-9. [DOI: 10.1161/circgenetics.108.792192] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Spatial and timely variations in QT interval, even within its normal range, may underlie susceptibility to cardiac arrhythmias and sudden cardiac death. Given its important role in cardiac electrophysiology, we hypothesized that common genetic variation in ankyrin-B gene (
ANK2
) might modify QT interval length.
Methods and Results—
The study population consisted of 1188 participants of the World Health Organizational Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (WHO MONICA) general population survey Cooperative Health Research in the Region of Augsburg (KORA S3). Corrected QT interval was calculated using population specific linear regression formulas. A total of 22 single-nucleotide polymorphisms in the genomic region of
ANK2
gene were genotyped using TaqMan technology. In a replication study, 6 single nucleotide polymorphisms were genotyped in 3890 individuals from a second population study (KORA S4). The rare variant of the single-nucleotide polymorphism rs6850768 (allele frequency, 0.28) significantly influenced duration of the QT interval, both in KORA S3 and KORA S4 populations. In homozygotes, the shortening of the QT interval was 3.79 ms (95% CI, 1.48 to 5.58;
P
=0.001 and
P
=0.0008 for log-additive and dominant model, respectively) in KORA S3 and 2.94 ms (95% CI, 1.11 to 4.77;
P
=0.001 and
P
=0.006 for log-additive and dominant genetic model, respectively) in KORA S4. A common 2-locus haplotype (rs11098171-rs6850768; population frequency, 28%) was associated with a QT interval difference of 2.85 ms (permutation;
P
=0.006) in KORA S3 and 1.23 ms (permutation;
P
=0.009) in KORA S4. Reverse transcription–polymerase chain reaction expression analysis of the human
ANK2
5′ genomic region in the human left ventricular tissue revealed 2 previously unidentified
ANK2
5′ exons in the proximity of the identified variants.
Conclusions—
Common genetic variants juxtaposed with novel exons in the distant 5′ genomic region of
ANK2
influence the QT interval length in the general population. These findings support the role of ankyrin-B in normal cardiac electric activity.
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Affiliation(s)
- Kamil Sedlacek
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Klaus Stark
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Shane R. Cunha
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Arne Pfeufer
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Stefan Weber
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Iris Berger
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Siegfried Perz
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Stefan Kääb
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Hans-Erich Wichmann
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Peter J. Mohler
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Christian Hengstenberg
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
| | - Andreas Jeron
- From the Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Regensburg, Germany (Ka.S., Kl.S., S.W., I.B., C.H., A.J.); Clinic of Cardiology and Center for Cardiovascular Research, IKEM, Prague, Czech Republic (Ka.S.); Departments of Internal Medicine, Molecular Physiology, and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa (S.R.C., P.J.M.); Institut für Humangenetik (A.P.), HelmholtzZentrum München, Neuherberg, Germany; Institute for
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14
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Dysfunction in ankyrin-B-dependent ion channel and transporter targeting causes human sinus node disease. Proc Natl Acad Sci U S A 2008; 105:15617-22. [PMID: 18832177 DOI: 10.1073/pnas.0805500105] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The identification of nearly a dozen ion channel genes involved in the genesis of human atrial and ventricular arrhythmias has been critical for the diagnosis and treatment of fatal cardiovascular diseases. In contrast, very little is known about the genetic and molecular mechanisms underlying human sinus node dysfunction (SND). Here, we report a genetic and molecular mechanism for human SND. We mapped two families with highly penetrant and severe SND to the human ANK2 (ankyrin-B/AnkB) locus. Mice heterozygous for AnkB phenocopy human SND displayed severe bradycardia and rate variability. AnkB is essential for normal membrane organization of sinoatrial node cell channels and transporters, and AnkB is required for physiological cardiac pacing. Finally, dysfunction in AnkB-based trafficking pathways causes abnormal sinoatrial node (SAN) electrical activity and SND. Together, our findings associate abnormal channel targeting with human SND and highlight the critical role of local membrane organization for sinoatrial node excitability.
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15
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Silva GJJ, Pereira AC, Krieger EM, Krieger JE. Genetic mapping of a new heart rate QTL on chromosome 8 of spontaneously hypertensive rats. BMC MEDICAL GENETICS 2007; 8:17. [PMID: 17419875 PMCID: PMC1865373 DOI: 10.1186/1471-2350-8-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Accepted: 04/09/2007] [Indexed: 01/19/2023]
Abstract
Background Tachycardia is commonly observed in hypertensive patients, predominantly mediated by regulatory mechanisms integrated within the autonomic nervous system. The genetic loci and genes associated with increased heart rate in hypertension, however, have not yet been identified. Methods An F2 intercross of Spontaneously Hypertensive Rats (SHR) × Brown Norway (BN) linkage analysis of quantitative trait loci mapping was utilized to identify candidate genes associated with an increased heart rate in arterial hypertension. Results Basal heart rate in SHR was higher compared to that of normotensive BN rats (365 ± 3 vs. 314 ± 6 bpm, p < 0.05 for SHR and BN, respectively). A total genome scan identified one quantitative trait locus in a 6.78 cM interval on rat chromosome 8 (8q22–q24) that was responsible for elevated heart rate. This interval contained 241 genes, of which 65 are known genes. Conclusion Our data suggest that an influential genetic region located on the rat chromosome 8 contributes to the regulation of heart rate. Candidate genes that have previously been associated with tachycardia and/or hypertension were found within this QTL, strengthening our hypothesis that these genes are, potentially, associated with the increase in heart rate in a hypertension rat model.
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Affiliation(s)
- Gustavo JJ Silva
- Department of Medicine-LIM13, Heart Institute (InCor), University of São Paulo Medical School, Av. Dr. Enéas de Carvalho Aguiar, 44, 10o andar, 05403-000, São Paulo, SP, Brazil
| | - Alexandre C Pereira
- Department of Medicine-LIM13, Heart Institute (InCor), University of São Paulo Medical School, Av. Dr. Enéas de Carvalho Aguiar, 44, 10o andar, 05403-000, São Paulo, SP, Brazil
| | - Eduardo M Krieger
- Department of Medicine-LIM13, Heart Institute (InCor), University of São Paulo Medical School, Av. Dr. Enéas de Carvalho Aguiar, 44, 10o andar, 05403-000, São Paulo, SP, Brazil
| | - José E Krieger
- Department of Medicine-LIM13, Heart Institute (InCor), University of São Paulo Medical School, Av. Dr. Enéas de Carvalho Aguiar, 44, 10o andar, 05403-000, São Paulo, SP, Brazil
- Laboratório de Genética e Cardiologia Molecular, Instituto do Coração (InCor) da Faculdade de Medicina da Universidade de São Paulo, Brazil, Av. Dr. Enéas de Carvalho Aguiar, 44 São Paulo, Brazil
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16
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Duong C, Charron S, Xiao C, Hamet P, Ménard A, Roy J, Deng AY. Distinct quantitative trait loci for kidney, cardiac, and aortic mass dissociated from and associated with blood pressure in Dahl congenic rats. Mamm Genome 2006; 17:1147-61. [PMID: 17143582 DOI: 10.1007/s00335-006-0086-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Accepted: 08/30/2006] [Indexed: 01/19/2023]
Abstract
Blood pressure (BP) is largely determined by quantitative trait loci (QTLs) in Dahl salt-sensitive (DSS) rats. Little is known about QTLs controlling kidney (K), cardiac (C), and aortic (A) mass (i.e. Km, Cm, and Am, respectively) of DSS rats independent of BP. Their identification can facilitate our understanding of end organ damage. In this work, 36 congenic strains were employed to define QTLs for Km, Cm, and Am either independent of or associated with BP. Five new QTLs, i.e., KmQTLs, that influence Km independent of Cm, Am, and BP were defined. Four new CakmQTLs were defined for Cm, Am, and Km independent of BP. Among them, the CakmC10QTL1 interval contained 13 genes and undefined loci, and none was known to influence the phenotypes in question, paving the way for a novel gene discovery. Among 17 individual QTLs for BP, 14 also affected Cm, Km, and Am, i.e., they are BpcakmQTLs. In contrast, one BpQTL had no effect on Cm, Am, and Kam. Therefore, BP and Cm, Am, and Km have distinct and shared genetic determinants. The discovery of individual Km and Cakm QTLs will likely facilitate the identification of mechanisms underlying renal, cardiac, and/or aortic hypertrophy independent of hypertension.
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Affiliation(s)
- Chenda Duong
- Research Centre, Centre Hospitalier de l'Université de Montréal (CHUM), Montréal, Québec, Canada
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17
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Mott R. Finding the molecular basis of complex genetic variation in humans and mice. Philos Trans R Soc Lond B Biol Sci 2006; 361:393-401. [PMID: 16524828 PMCID: PMC1609339 DOI: 10.1098/rstb.2005.1798] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
I survey the state of the art in complex trait analysis, including the use of new experimental and computational technologies and resources becoming available, and the challenges facing us. I also discuss how the prospects of rodent model systems compare with association mapping in humans.
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Affiliation(s)
- Richard Mott
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
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18
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Laramie JM, Wilk JB, Hunt SC, Ellison RC, Chakravarti A, Boerwinkle E, Myers RH. Evidence for a gene influencing heart rate on chromosome 5p13-14 in a meta-analysis of genome-wide scans from the NHLBI Family Blood Pressure Program. BMC MEDICAL GENETICS 2006; 7:17. [PMID: 16509988 PMCID: PMC1413518 DOI: 10.1186/1471-2350-7-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Accepted: 03/01/2006] [Indexed: 11/25/2022]
Abstract
BACKGROUND Elevated resting heart rate has been shown in multiple studies to be a strong predictor of cardiovascular disease. Previous family studies have shown a significant heritable component to heart rate with several groups conducting genomic linkage scans to identify quantitative trait loci. METHODS We performed a genome-wide linkage scan to identify quantitative trait loci influencing resting heart rate among 3,282 Caucasians and 3,989 African-Americans in three independent networks comprising the Family Blood Pressure Program (FBPP) using 368 microsatellite markers. Mean heart rate measurements were used in a regression model including covariates for age, body mass index, pack-years, currently drinking alcohol (yes/no), hypertension status and medication usage to create a standardized residual for each gender/ethnic group within each study network. This residual was used in a nonparametric variance component model to generate a LOD score and a corresponding P value for each ethnic group within each study network. P values from each ethnic group and study network were merged using an adjusted Fisher's combining P values method and the resulting P values were converted to LOD scores. The entire analysis was redone after individuals currently taking beta-blocker medication were removed. RESULTS We identified significant evidence of linkage (LOD = 4.62) to chromosome 10 near 142.78 cM in the Caucasian group of HyperGEN. Between race and network groups we identified a LOD score of 1.86 on chromosome 5 (between 39.99 and 45.34 cM) in African-Americans in the GENOA network and the same region produced a LOD score of 1.12 among Caucasians within a different network (HyperGEN). Combining all network and race groups we identified a LOD score of 1.92 (P = 0.0013) on chromosome 5p13-14. We assessed heterogeneity for this locus between networks and ethnic groups and found significant evidence for low heterogeneity (P < or = 0.05). CONCLUSION We found replication (LOD > 1) between ethnic groups and between study networks with low heterogeneity on chromosome 5p13-14 suggesting that a gene in this region influences resting heart rate.
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Affiliation(s)
- Jason M Laramie
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- Department of Bioinformatics, Boston University, MA, USA
| | - Jemma B Wilk
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- Section of Preventive Medicine and Epidemiology, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Steven C Hunt
- Cardiovascular Genetics, University of Utah, Salt Lake City, UT, USA
| | - R Curtis Ellison
- Section of Preventive Medicine and Epidemiology, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Aravinda Chakravarti
- Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Eric Boerwinkle
- Human Genetics Center, University of Texas-Houston Health Science Center, Houston, TX, USA
| | - Richard H Myers
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA
- Section of Preventive Medicine and Epidemiology, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
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19
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Charron S, Lambert R, Eliopoulos V, Duong C, Ménard A, Roy J, Deng AY. A loss of genome buffering capacity of Dahl salt-sensitive model to modulate blood pressure as a cause of hypertension. Hum Mol Genet 2005; 14:3877-84. [PMID: 16278234 DOI: 10.1093/hmg/ddi412] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Essential hypertension is a complex trait influenced by multiple genes known as quantitative trait loci (QTLs) for blood pressure (BP). It is not clear, however, what roles these QTLs play in maintaining normotension. Insights gained toward the maintenance of normotension will shed light on how hypertension can result from a deficiency or malfunctioning of this maintenance. Currently, congenic strains were systematically constructed using Dahl salt-sensitive (DSS) and Lewis (LEW) rats not only to define QTLs (i.e. in DSS background), but also to ascertain effects of the same QTLs in preserving normotension (i.e. in LEW background), a first such study. Results showed that although LEW alleles for two QTLs on Chromosome (Chr) 18 lowered BP on the DSS background, their BP-increasing DSS alleles failed to influence BP in the LEW background. To further prove that the LEW background is resistant and the DSS background is susceptible to the effects of QTLs, BP-increasing alleles of a QTL on Chr 2 were introgressed into the DSS background, and its BP-decreasing alleles into the LEW background. Indeed, there was no BP-decreasing effect on the LEW background while demonstrating a BP-increasing effect on the DSS background. Thus, a genetic regulation of BP QTLs in the LEW genome inhibits BP changes by nullifying the effects of BP-altering QTLs. In comparison, the DSS genome must have lost the buffering capacity for stabilizing BP. The current work presents good evidence that a lack of regulation for functions of BP QTLs is a potential underlying cause of hypertension.
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20
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Nemoto K, Sekimoto M, Fukamachi K, Kageyama H, Degawa M, Hamadai M, Hendley ED, Macrae IM, Clark JS, Dominiczak AF, Ueyama T. No involvement of the nerve growth factor gene locus in hypertension in spontaneously hypertensive rats. Hypertens Res 2005; 28:155-63. [PMID: 16025743 DOI: 10.1291/hypres.28.155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Sympathetic hyper-innervation and increased levels of nerve growth factor (NGF), an essential neurotrophic factor for sympathetic neurons, have been observed in the vascular tissues of spontaneously hypertensive rats (SHRs). Such observations have suggested that the pathogenesis of hypertension might involve a qualitative or quantitative abnormality in the NGF protein, resulting from a significant mutation in the gene's promoter or coding region. In the present study, we analyzed the nucleotide sequences of the cis-element of the NGF gene in SHRs, stroke-prone SHRs (SHRSPs), and normotensive Wistar-Kyoto (WKY) rats. The present analyses revealed some differences in the 3-kb promoter region, coding exon, and 3' untranslated region (3'UTR) for the NGF gene among those strains. However, the observed differences did not lead to changes in promoter activity or to amino acid substitution; nor did they represent a link between the 3'UTR mutation of SHRSPs and elevated blood pressure in an F2 generation produced by crossbreeding SHRSPs with WKY rats. These results suggest that the NGF gene locus is not involved in hypertension in SHR/ SHRSP strains. The present study also revealed two differences between SHRs and WKY rats, as found in cultured vascular smooth muscle cells and in mRNA prepared from each strain. First, SHRs had higher expression levels of c-fos and c-jun genes, which encode the component of the AP-1 transcription factor that activates NGF gene transcription. Second, NGF mRNAs prepared from SHRs had a longer 3'UTR than those prepared from WKY rats. Although it remains to be determined whether these events play a role in the hypertension of SHR/SHRSP strains, the present results emphasize the importance of actively searching for aberrant trans-acting factor(s) leading to the enhanced expression of the NGF gene and NGF protein in SHR/SHRSP strains.
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Affiliation(s)
- Kiyomitsu Nemoto
- Department of Molecular Toxicology and COE Program in the 21 st Century, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
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21
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Eliopoulos V, Dutil J, Deng Y, Grondin M, Deng AY. Severe hypertension caused by alleles from normotensive Lewis for a quantitative trait locus on chromosome 2. Physiol Genomics 2005; 22:70-5. [PMID: 15827238 DOI: 10.1152/physiolgenomics.00019.2005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pursuing fully a suggestion from linkage analysis that there might be a quantitative trait locus (QTL) for blood pressure (BP) in a chromosome (Chr) 2 region of the Dahl salt-sensitive rat (DSS), four congenic strains were made by replacing various fragments of DSS Chr 2 with those of Lewis (LEW). Consequently, a BP QTL was localized to a segment of around 3 cM or near 3 Mb on Chr 2 by comparative congenics. The BP-augmenting alleles of this QTL originated from the LEW rat, a normotensive strain compared with DSS. The dissection of a QTL with such a paradoxical effect illustrated the power of congenics in unearthing a gene hidden in the context of the whole animal system, presumably by interactions with other genes. The locus for the angiotensin II receptor AT-1B ( Agtr1b) is not supported as a candidate gene for the QTL because a congenic strain harboring it did not have an effect on BP. There are ∼19 known and unknown genes present in the QTL interval. Among them, no standout candidate genes are reputed to affect BP. Thus the QTL will likely represent a novel gene for BP regulation.
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Affiliation(s)
- Vasiliki Eliopoulos
- Research Centre-Centre Hospitalier de l'Université de Montréal (CHUM), Hôtel Dieu, Montreal, Quebec, Canada
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22
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Flint J, Valdar W, Shifman S, Mott R. Strategies for mapping and cloning quantitative trait genes in rodents. Nat Rev Genet 2005; 6:271-86. [PMID: 15803197 DOI: 10.1038/nrg1576] [Citation(s) in RCA: 382] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Over the past 15 years, more than 2,000 quantitative trait loci (QTLs) have been identified in crosses between inbred strains of mice and rats, but less than 1% have been characterized at a molecular level. However, new resources, such as chromosome substitution strains and the proposed Collaborative Cross, together with new analytical tools, including probabilistic ancestral haplotype reconstruction in outbred mice, Yin-Yang crosses and in silico analysis of sequence variants in many inbred strains, could make QTL cloning tractable. We review the potential of these strategies to identify genes that underlie QTLs in rodents.
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Affiliation(s)
- Jonathan Flint
- Wellcome Trust Centre for Human Genetics, Oxford University, Roosevelt Drive, Oxford OX3 7BN, United Kingdom.
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23
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Dutil J, Eliopoulos V, Tremblay J, Hamet P, Charron S, Deng AY. Multiple Quantitative Trait Loci for Blood Pressure Interacting Epistatically and Additively on Dahl Rat Chromosome 2. Hypertension 2005; 45:557-64. [PMID: 15738349 DOI: 10.1161/01.hyp.0000158841.71658.5e] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Our previous work demonstrated 2 quantitative trait loci (QTLs), C2QTL1 and C2QTL2, for blood pressure (BP) located on chromosome (Chr) 2 of Dahl salt-sensitive (DSS) rats. However, for a lack of markers, the 2 congenic strains delineating C2QTL1 and C2QTL2 could not be separated. The position of the C2QTL1 was only inferred by comparing 2 congenic strains, one having and another lacking a BP effect. Furthermore, it was not known how adjacent QTLs would interact with one another on Chr 2. In the current investigation, first, a critical chromosome marker was developed to separate 2 C2QTLs. Second, a congenic substrain was created to cover a chromosome fragment thought to harbor C2QTL1. Finally, a series of congenic strains was produced to systematically and comprehensively cover the entire Chr 2 segment containing C2QTL2 and other regions previously untested. Consequently, a total of 3 QTLs were discovered, with C2QTL3 located between C2QTL1 and C2QTL2. C2QTL1, C2QTL2, and C2QTL3 reside in chromosome segments of 5.7 centiMorgan (cM), 3.5 cM, and 1.5 cM, respectively. C2QTL1 interacted epistatically with either C2QTL2 or C2QTL3, whereas C2QTL2 and C2QTL3 showed additive effects to each other. These results suggest that BP QTLs closely linked in a segment interact epistatically and additively to one another on Chr 2.
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Affiliation(s)
- Julie Dutil
- Research Centre-CHUM, 3840 rue St. Urbain, Montréal, Québec, Canada
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Dutil J, Eliopoulos V, Marchand EL, Devlin AM, Tremblay J, Prithiviraj K, Hamet P, Migneault A, deBlois D, Deng AY. A quantitative trait locus for aortic smooth muscle cell number acting independently of blood pressure: implicating the angiotensin receptor AT1B gene as a candidate. Physiol Genomics 2005; 21:362-9. [PMID: 15741507 DOI: 10.1152/physiolgenomics.00063.2004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vascular hyperplasia may be involved in the remodeling of vasculature. It was unknown whether there were genetic determinants for aortic smooth muscle cell number (SMCN) and, if so, whether they acted independently of those for blood pressure (BP). To unravel this issue, we utilized congenic strains previously constructed for BP studies. These strains were made by replacing various chromosome 2 segments of the Dahl salt-sensitive (S) rat with those of the Milan normotensive rat (MNS). We measured and compared SMCN in aortic cross-sectional areas and BPs of these strains. Consequently, a quantitative trait locus (QTL) for SMCN was localized to a chromosome region not containing a BP QTL, but harboring the locus for the angiotensin II receptor AT1B (Agtr1b). Agtr1b became a candidate for the SMCN QTL because 1) two significant mutations were found in the coding region between S and all congenic strains possessing the MNS alleles, and 2) contractile responses to angiotensin II were significantly and selectively reduced in congenic rats harboring the MNS alleles of the SMCN QTL compared with S rats. The current investigation presents the first line of evidence that a QTL for aortic SMCN exists, and it acts independently of QTLs for BP. The relevant congenic strains developed therein potentially provide novel mammalian models for the studies of vascular remodeling disorders.
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Affiliation(s)
- Julie Dutil
- Research Centre-Centre Hospitalier de l'Université de Montréal (CHUM), Montreal, Quebec, Canada
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Grondin M, Eliopoulos V, Lambert R, Deng Y, Ariyarajah A, Moujahidine M, Dutil J, Charron S, Deng AY. Complete and overlapping congenics proving the existence of a quantitative trait locus for blood pressure on Dahl rat chromosome 17. Physiol Genomics 2005; 21:112-6. [PMID: 15632271 DOI: 10.1152/physiolgenomics.00275.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Linkage studies suggested that a quantitative trait locus (QTL) for blood pressure (BP) was present in a region on chromosome 17 (Chr 17) of Dahl salt-sensitive (DSS) rats. A subsequent congenic strain targeting this QTL, however, could not confirm it. These conflicting results called into question the validity of localization of a QTL by linkage followed by the use of a congenic strain made with an incomplete chromosome coverage. To resolve this issue, we constructed five new congenic strains, designated C17S.L1 to C17S.L5, that completely spanned the +/-2 LOD confidence interval supposedly containing the QTL. Each congenic strain was made by replacing a segment of the DSS rat by that of the normotensive Lewis (LEW) rat. The only section to be LL homozygous is the region on Chr 17 specified in a congenic strain, as evidenced by a total genome scan. The results showed that BPs of C17S.L1 and C17S.L2 were lower (P < 0.04) than that of DSS rats. In contrast, BPs of C17S.L3, C17S.L4, and C17S.L5 were not different (P > 0.6) from that of DSS rats. Consequently, a BP QTL must be located in an interval of approximately 15 cM shared between C17S.L1 and C17S.L2 and unique to them both, as opposed to C17S.L3, C17S.L4, and C17S.L5. The present study illustrates the importance of thorough chromosome coverage, the necessity for a genome-wide screening, and the use of "negative" controls in physically mapping a QTL by congenic strains.
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Affiliation(s)
- Myrian Grondin
- Research Centre, Centre Hospitalier de l'Universite de Montréal (CHUM), Montréal, Québec, Canada
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Martin LJ, Comuzzie AG, Sonnenberg GE, Myklebust J, James R, Marks J, Blangero J, Kissebah AH. Major quantitative trait locus for resting heart rate maps to a region on chromosome 4. Hypertension 2004; 43:1146-51. [PMID: 14993199 DOI: 10.1161/01.hyp.0000122873.42047.17] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Multiple studies have identified resting heart rate as a risk factor for cardiovascular disease independent of other cardiovascular disease risk factors (such as dyslipidemia and hypertension). Previous studies have examined heart rate in hypertensive individuals, but little is known about the genetic determination of resting heart rate in a normal population. Therefore, our objective was to perform a genome screen on a population containing normotensive and hypertensive individuals. We performed variance decomposition linkage analysis using maximum likelihood methods at approximately 10 cM intervals in 2209 individuals of predominantly North European ancestry. We estimated the heritability of resting heart rate to be 26% and obtained significant evidence of linkage (logarithm of the odds [LOD]=3.9) for resting heart rate on chromosome 4q. This signal is in the same region as a quantitative trait locus (QTL) for long QT syndrome 4 and a QTL for heart rate in rats. Within the 1-LOD unit support interval, there are 2 strong candidates: ankyrin-B and myozenin 2.
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Affiliation(s)
- Lisa J Martin
- Department of Pediatrics, Center for Epidemiology and Biostatistics, Cincinnati Children's Hospital Medical Center, Mail Code 5041, 3333 Burnet Avenue, Cincinnati, Ohio 45229, USA.
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Printz MP, Jirout M, Jaworski R, Alemayehu A, Kren V. Genetic Models in Applied Physiology. HXB/BXH rat recombinant inbred strain platform: a newly enhanced tool for cardiovascular, behavioral, and developmental genetics and genomics. J Appl Physiol (1985) 2003; 94:2510-22. [PMID: 12736193 DOI: 10.1152/japplphysiol.00064.2003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review deals with the largest set of rat recombinant inbred (RI) strains and summarizes past and recent accomplishments with this platform for genetic mapping and analyses of divergent and complex traits. This strain, derived by crossing the spontaneously hypertensive rat, SHR/Ola, with a Brown Norway congenic, BN-Lx, carrying polydactyly-luxate syndrome, is referred to as HXB/BXH. The RI strain set has been used for linkage and association studies to identify quantitative trait loci for numerous cardiovascular phenotypes, including arterial pressure, stress-elicited heart rate, and pressor response, and metabolic traits, including insulin resistance, dyslipidemia and glucose handling, and left ventricular hypertrophy. The strain's utility has been enhanced with development of a new framework marker-based map and strain distribution patterns of polymorphic markers. Quantitative trait loci for behavioral traits mapped include loci for startle motor response and habituation, anxiety and locomotion traits associated with elevated plus maze, and conditioned taste aversion. The polydactyly-luxate syndrome Lx mutation has allowed the study of alleles important to limb development and malformation phenotypes as well as teratogens. The RI strains have guided development of numerous congenic strains to test locus assignments and to study the effect of genetic background. Although these strains were originally developed to aid in studies of rat genetic hypertension and morphogenetic abnormalities, this rodent platform has been shown to be equally powerful for a wide spectrum of traits and endophenotypes. These strains provide a ready and available vehicle for many physiological and pharmacological studies.
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Affiliation(s)
- Morton P Printz
- Department of Pharmacology, University of California San Diego, La Jolla, California 92093-0636, USA.
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