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Martina Klevstig,
Dmitry Manakov,
Dita Kasparova,
Iveta Brabcova,
Frantisek Papousek,
Jitka Zurmanova,
Vaclav Zidek,
Jan Silhavy,
Jan Neckar, Michal Pravenec,
Frantisek Kolar,
Olga Novakova,
Jiri Novotny
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ABSTRACT: Dysfunction or abnormalities in the regulation of fatty acid translocase Cd36, a multifunctional membrane protein participating in uptake of long-chain fatty acids, has been linked to the development of heart diseases both in animals and humans. We have previously shown that the Cd36 transgenic spontaneously hypertensive rat (SHR-Cd36), with a wild type Cd36, has higher susceptibility to ischemic ventricular arrhythmias when compared to spontaneously hypertensive rat (SHR) carrying a mutant Cd36 gene, which may have been related to increased β-adrenergic responsiveness of these animals (Neckar et al., 2012 Physiol. Genomics 44:173-182). The present study aimed to determine whether the insertion of the wild type Cd36 into SHR would affect the function of myocardial G protein-regulated adenylyl cyclase (AC) signaling. β-Adrenergic receptors (β-ARs) were characterized by radioligand-binding experiments and the expression of selected G protein subunits, AC, and protein kinase A (PKA) was determined by RT-PCR and Western blot analyses. There was no significant difference in the amount of trimeric G proteins, but the number of β-ARs was higher (by about 35 %) in myocardial preparations from SHR-Cd36 as compared to SHR. Besides that, transgenic rats expressed increased amount (by about 20 %) of the dominant myocardial isoforms AC5/6 and contained higher levels of both nonphosphorylated (by 11 %) and phosphorylated (by 45 %) PKA. Differently stimulated AC activity in SHR-Cd36 significantly exceeded (by about 18-30 %) the enzyme activity in SHR. Changes at the molecular level were reflected by higher contractile responses to stimulation by the adrenergic agonist dobutamine. In summary, it can be concluded that the increased susceptibility to ischemic arrhythmias of SHR-Cd36 is attributable to upregulation of some components of the β-AR signaling pathway, which leads to enhanced sensitization of AC and increased cardiac adrenergic responsiveness.
Pflügers Archiv - European Journal of Physiology 05/2013; · 4.46 Impact Factor
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ABSTRACT: Background
The angiotensin receptor blocker telmisartan has unique chemical properties that enable it to partially activate the peroxisome proliferator activated receptor gamma (PPARG) as well as block angiotensin II type 1 receptors.Methods
To directly test whether some of the metabolic effects of telmisartan require the presence of PPARG, we studied mice in which the gene (Pparg) for PPARG had been deleted in fat or in muscle.ResultsWe found that knockout of Pparg in fat tissue greatly impaired the ability of telmisartan to increase adiponectin levels and to enhance sensitivity to insulin-stimulated glucose incorporation into adipose tissue lipids. In contrast, muscle-specific Pparg knockout had relatively little or no impact on the ability of telmisartan to increase adiponectin levels or affect glucose metabolism either in fat or muscle. These findings provide compelling evidence that the ability of telmisartan to increase adiponectin levels and stimulate glucose use in adipose tissue may depend on the presence of PPARG in fat.Conclusions
We conclude that PPARG in adipose tissue is required for at least several of the metabolic actions of telmisartan.
American Journal of Hypertension 02/2013; · 3.18 Impact Factor
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Michal Pravenec,
Viktor Kozich,
Jakub Krijt,
Jitka Sokolová,
Václav Zídek,
Vladimír Landa,
Miroslava Simáková,
Petr Mlejnek,
Jan Silhavy,
Olena Oliyarnyk,
Ludmila Kazdová,
Theodore W Kurtz
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ABSTRACT: BACKGROUND The role of folate deficiency and associated hyperhomocysteinemia in the pathogenesis of metabolic syndrome is not fully established. In the current study, we analyzed the role of folate deficiency in pathogenesis of the metabolic syndrome in the spontaneously hypertensive rat (SHR). METHODS Metabolic and hemodynamic traits were assessed in SHR/Ola rats fed either folate-deficient or control diet for 4 weeks starting at the age of 3 months. RESULTS Compared to SHRs fed a folate-replete diet, SHRs fed a folate-deficient diet showed significantly reduced serum folate (104±5 vs. 11±1 nmol/L, P < 0.0005) and urinary folate excretion (4.3±0.6 vs. 1.2±0.1 nmol/16h, P < 0.0005) together with a near 3-fold increase in plasma total homocysteine concentration (4.5±0.1 vs 13.1±0.7 μmol/L, P < 0.0005), ectopic fat accumulation in liver, and impaired glucose tolerance. Folate deficiency also increased systolic blood pressure by approximately 15mm Hg (P < 0.01). In addition, the low-folate diet was accompanied by significantly reduced activity of antioxidant enzymes and increased concentrations of lipoperoxidation products in liver, renal cortex, and heart. CONCLUSIONS These findings demonstrate that the SHR model is susceptible to the adverse metabolic and hemodynamic effects of low dietary intake of folate. The results are consistent with the hypothesis that folate deficiency can promote oxidative stress and multiple features of the metabolic syndrome that are associated with increased risk for diabetes and cardiovascular disease.
American Journal of Hypertension 01/2013; 26(1):135-40. · 3.18 Impact Factor
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Massimiliano Mancini,
Enrico Petretto,
Christina Kleinert,
Angela Scavone,
Tisham De,
Stuart Cook,
Jan Silhavy,
Vaclav Zidek, Michal Pravenec,
Giulia d'Amati,
Paolo G Camici
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ABSTRACT: The mechanisms underlying coronary microvascular remodeling and dysfunction, which are critical determinants of abnormal myocardial blood flow regulation in human hypertension, are poorly understood. The spontaneously hypertensive rat (SHR) exhibits many features of human hypertensive cardiomyopathy. We demonstrate that remodeling of intramural coronary arterioles is apparent in the SHR already at 4 weeks of age, i.e. before the onset of systemic hypertension. To uncover possible genetic determinants of coronary microvascular remodeling, we carried out detailed histological and histomorphometric analysis of the heart and coronary vasculature in 30 weeks old SHR, age-matched Brown Norway (BN-Lx) parentals and BXH/HXB recombinant inbred (RI) strains. Using previously mapped expression quantitative trait loci (eQTLs), we carried out a genome-wide association analysis between genetic determinants of cardiac gene expression and histomorphometric traits. This identified 36 robustly mapped eQTLs in the heart which were associated with medial area of intramural coronary arterioles [false discovery rate (FDR) ~5 %]. Transcripts, which were both under cis-acting genetic regulation and significantly correlated with medial area (FDR <5 %), but not with blood pressure indices, were prioritized and four candidate genes were identified (Rtel1, Pla2g5, Dnaja4 and Rcn2) according to their expression levels and biological functions. Our results demonstrate that genetic factors play a role in the development of coronary microvascular remodeling and suggest blood pressure independent candidate genes for further functional experiments.
Archiv für Kreislaufforschung 01/2013; 108(1):316. · 7.35 Impact Factor
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Katharina Katter,
Aron M Geurts,
Orsolya Hoffmann,
Lajos Mátés,
Vladimir Landa,
László Hiripi,
Carol Moreno,
Jozef Lazar,
Sanum Bashir,
Vaclav Zidek, [......],
Molly Corbett,
Artur Rangel Filho,
Matthew R Hodges,
Michael Bader,
Zoltán Ivics,
Howard J Jacob, Michal Pravenec,
Zsuzsanna Bosze,
Thomas Rülicke,
Zsuzsanna Izsvák
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ABSTRACT: Germline transgenesis is an important procedure for functional investigation of biological pathways, as well as for animal biotechnology. We have established a simple, nonviral protocol in three important biomedical model organisms frequently used in physiological studies. The protocol is based on the hyperactive Sleeping Beauty transposon system, SB100X, which reproducibly promoted generation of transgenic founders at frequencies of 50-64, 14-72, and 15% in mice, rats, and rabbits, respectively. The SB100X-mediated transgene integrations are less prone to genetic mosaicism and gene silencing as compared to either the classical pronuclear injection or to lentivirus-mediated transgenesis. The method was successfully applied to a variety of transgenes and animal models, and can be used to generate founders with single-copy integrations. The transposon vector also allows the generation of transgenic lines with tissue-specific expression patterns specified by promoter elements of choice, exemplified by a rat reporter strain useful for tracking serotonergic neurons. As a proof of principle, we rescued an inborn genetic defect in the fawn-hooded hypertensive rat by SB100X transgenesis. A side-by-side comparison of the SB100X- and piggyBac-based protocols revealed that the two systems are complementary, offering new opportunities in genome manipulation.-Katter, K., Geurts, A. M., Hoffmann, O., Mátés, L., Landa,V., Hiripi, L., Moreno, C., Lazar, J., Bashir, S., Zidek, V., Popova, E., Jerchow, B., Becker, K., Devaraj, A., Walter, I., Grzybowksi, M., Corbett, M., Rangel Filho, A., Hodges, M. R., Bader, M., Ivics, Z., Jacob, H. J., Pravenec, M., Bősze, Z., Rülicke, T., Izsvák, Z. Transposon-mediated transgenesis, transgenic rescue, and tissue-specific gene expression in rodents and rabbits.
The FASEB Journal 11/2012; · 5.71 Impact Factor
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ABSTRACT: AIMS: Human genome-wide association studies (GWAS) of hypertension identified only few susceptibility loci with large-effect that were replicated across populations. The vast majority of genes detected by GWAS have small-effect and the regulatory mechanisms through which these genetic variants cause disease remain mostly unclear. Here, we used comparative genomics between human and an established rat model of hypertension to explore the transcriptional mechanisms mediating the effect of genes identified in 15 hypertension GWAS. METHODS AND RESULTS: Time-series analysis of radiotelemetric blood pressure (BP) was performed to assess eleven parameters of BP-variation in recombinant inbred strains derived from the Spontaneously Hypertensive Rat. BP-data were integrated with ∼27,000 expression QTLs (eQTLs) mapped across seven tissues, detecting >8,000 significant associations between eQTL genes and BP-variation in the rat. We then compiled a large catalogue of human genes from GWAS of hypertension and identified a sub-set of 2,292 rat-human orthologous genes. Expression levels for 795 (34%) of these genes correlated with BP-variation across rat tissues: 51 genes were cis-regulated, whereas 459 were trans-regulated and enriched for 'calcium signalling pathway' (P=9.6x10-6) and 'ion channel' genes (P=3.5x10-7), which are important determinants of hypertension. We identified 158 clusters of trans-eQTLs, annotated the underlying 'master regulator' genes and found significant over-representation in the human hypertension gene-set (enrichment P=5x10-4). CONCLUSION: We showed extensive conservation of trans-regulated genes and their master regulators between rat and human hypertension. These findings reveal that small-effect genes associated with hypertension by human GWAS are likely to exert their action through coordinate regulation of pathogenic pathways.
Cardiovascular research 10/2012; · 5.80 Impact Factor
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Marieke Simonis,
Santosh S Atanur,
Sam Linsen,
Victor Guryev,
Frans-Paul Ruzius,
Laurence Game,
Nico Lansu,
Ewart de Bruijn,
Sebastiaan van Heesch,
Steven Jm Jones, Michal Pravenec,
Tim J Aitman,
Edwin Cuppen
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ABSTRACT: With the advent of next generation sequencing it has become possible to detect genomic variation on a large scale. However, predicting which genomic variants are damaging to gene function remains a challenge, as knowledge of the effects of genomic variation on gene expression is still limited. Recombinant inbred panels are powerful tools to study the cis and trans effects of genetic variation on molecular phenotypes such as gene expression.
We generated a comprehensive inventory of genomic differences between the two founder strains of the rat HXB/BXH recombinant inbred panel: SHR/OlaIpcv and BN-Lx/Cub. We identified 3.2 million single nucleotide variants, 425,924 small insertions and deletions, 907 copy number changes and 1,094 large structural genetic variants. RNA-sequencing analyses on liver tissue of the two strains identified 532 differentially expressed genes and 40 alterations in transcript structure. We identified both coding and non-coding variants that correlate with differential expression and alternative splicing. Furthermore, structural variants, in particular gene duplications, show a strong correlation with transcriptome alterations.
We show that the panel is a good model for assessing the genetic basis of phenotypic heterogeneity and for providing insights into possible underlying molecular mechanisms. Our results reveal a high diversity and complexity underlying quantitative and qualitative transcriptional differences.
Genome biology 04/2012; 13(4):r31. · 6.63 Impact Factor
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ABSTRACT: The temporal relationship of hepatic steatosis and changes in liver oxidative stress and fatty acid (FA) composition to the
development of non-alcoholic steatohepatitis (NASH) remain to be clearly defined. Recently, we developed an experimental model
of hepatic steatosis and NASH, the transgenic spontaneously hypertensive rat (SHR) that overexpresses a dominant positive
form of the human SREBP-1a isoform in the liver. These rats are genetically predisposed to hepatic steatosis at a young age
that ultimately progresses to NASH in older animals. Young transgenic SHR versus SHR controls exhibited simple hepatic steatosis
which was associated with significantly increased hepatic levels of oxidative stress markers, conjugated dienes, and TBARS,
with decreased levels of antioxidative enzymes and glutathione and lower concentrations of plasma α- and γ-tocopherol. Transgenic
rats exhibited increased plasma levels of saturated FA, decreased levels of n−3 and n−6 polyunsaturated FA (PUFA), and increased n−6/n−3 PUFA ratios. These results are consistent with the hypothesis that excess fat accumulation in the liver in association
with increased oxidative stress and disturbances in the metabolism of saturated and unsaturated fatty acids may precede and
contribute to the primary pathogenesis of NASH.
Molecular and Cellular Biochemistry 04/2012; 335(1):119-125. · 2.06 Impact Factor
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Josef Houštek,
Kateřina Hejzlarová,
Marek Vrbacký,
Zdeněk Drahota,
Vladimír Landa,
Václav Zídek,
Petr Mlejnek,
Miroslava Šimáková,
Jan Šilhavy,
Ivan Mikšík,
Ludmila Kazdová,
Olena Oliyarnyk,
Theodore Kurtz, Michal Pravenec
[show abstract]
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ABSTRACT: Common inbred strains of the laboratory rat can be divided into four different mitochondrial DNA haplotype groups represented by the SHR, BN, LEW, and F344 strains. In the current study, we investigated the metabolic and hemodynamic effects of the SHR vs. LEW mitochondrial genomes by comparing the SHR to a new SHR conplastic strain, SHR-mt(LEW); these strains are genetically identical except for their mitochondrial genomes. Complete mitochondrial DNA (mtDNA) sequence analysis comparing the SHR and LEW strains revealed gene variants encoding amino acid substitutions limited to a single mitochondrial enzyme complex, NADH dehydrogenase (complex I), affecting subunits 2, 4, and 5. Two of the variants in the mt-Nd4 subunit gene are located close to variants known to be associated with exercise intolerance and diabetes mellitus in humans. No variants were found in tRNA or rRNA genes. These variants in mt-Nd2, mt-Nd4, and mt-Nd5 in the SHR-mt(LEW) conplastic strain were linked to reductions in oxidative and nonoxidative glucose metabolism in skeletal muscle. In addition, SHR-mt(LEW) conplastic rats showed increased serum nonesterified fatty acid levels and resistance to insulin stimulated incorporation of glucose into adipose tissue lipids. These results provide evidence that inherited variation in mitochondrial genes encoding respiratory chain complex I subunits, in the absence of variation in the nuclear genome and other confounding factors, can influence glucose and lipid metabolism when expressed on the nuclear genetic background of the SHR strain.
Physiological Genomics 03/2012; 44(9):487-94. · 2.73 Impact Factor
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Jan Neckář,
Jan Šilhavy,
Václav Zídek,
Vladimír Landa,
Petr Mlejnek,
Miroslava Šimáková,
J G Seidman,
Christine Seidman,
Ludmila Kazdová,
Martina Klevstig,
František Novák,
Marek Vecka,
František Papoušek,
Josef Houštěk,
Zdeněk Drahota,
Theodore W Kurtz,
František Kolář, Michal Pravenec
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ABSTRACT: CD36 fatty acid translocase plays a key role in supplying heart with its major energy substrate, long-chain fatty acids (FA). Previously, we found that the spontaneously hypertensive rat (SHR) harbors a deletion variant of Cd36 gene that results in reduced transport of long-chain FA into cardiomyocytes and predisposes the SHR to cardiac hypertrophy. In the current study, we analyzed the effects of mutant Cd36 on susceptibility to ischemic ventricular arrhythmias and myocardial infarction in adult SHR-Cd36 transgenic rats with wild-type Cd36 compared with age-matched SHR controls. Using an open-chest model of coronary artery occlusion, we found that SHR-Cd36 transgenic rats showed profound arrhythmogenesis resulting in significantly increased duration of tachyarrhythmias (207 ± 48 s vs. 55 ± 21 s, P < 0.05), total number of premature ventricular complexes (2,623 ± 517 vs. 849 ± 250, P < 0.05) and arrhythmia score (3.86 ± 0.18 vs. 3.13 ± 0.13, P < 0.001). On the other hand, transgenic SHR compared with SHR controls showed significantly reduced infarct size (52.6 ± 4.3% vs. 72.4 ± 2.9% of area at risk, P < 0.001). Similar differences were observed in isolated perfused hearts, and the increased susceptibility of transgenic SHR to arrhythmias was abolished by reserpine, suggesting the involvement of catecholamines. To further search for possible molecular mechanisms of altered ischemic tolerance, we compared gene expression profiles in left ventricles dissected from 6-wk-old transgenic SHR vs. age-matched controls using Illumina-based sequencing. Circadian rhythms and oxidative phosphorylation were identified as the top KEGG pathways, while circadian rhythms, VDR/RXR activation, IGF1 signaling, and HMGB1 signaling were the top IPA canonical pathways potentially important for Cd36-mediated effects on ischemic tolerance. It can be concluded that transgenic expression of Cd36 plays an important role in modulating the incidence and severity of ischemic and reperfusion ventricular arrhythmias and myocardial infarct size induced by coronary artery occlusion. The proarrhythmic effect of Cd36 transgene appears to be dependent on adrenergic stimulation.
Physiological Genomics 11/2011; 44(2):173-82. · 2.73 Impact Factor
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Chris McDermott-Roe,
Junmei Ye,
Rizwan Ahmed,
Xi-Ming Sun,
Anna Serafín,
James Ware,
Leonardo Bottolo,
Phil Muckett,
Xavier Cañas,
Jisheng Zhang, [......],
Marisol Ruiz-Meana,
David García-Dorado,
Joan X Comella,
Leanne E Felkin,
Paul J R Barton,
Zoltan Arany, Michal Pravenec,
Enrico Petretto,
Daniel Sanchis,
Stuart A Cook
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ABSTRACT: Left ventricular mass (LVM) is a highly heritable trait and an independent risk factor for all-cause mortality. So far, genome-wide association studies have not identified the genetic factors that underlie LVM variation, and the regulatory mechanisms for blood-pressure-independent cardiac hypertrophy remain poorly understood. Unbiased systems genetics approaches in the rat now provide a powerful complementary tool to genome-wide association studies, and we applied integrative genomics to dissect a highly replicated, blood-pressure-independent LVM locus on rat chromosome 3p. Here we identified endonuclease G (Endog), which previously was implicated in apoptosis but not hypertrophy, as the gene at the locus, and we found a loss-of-function mutation in Endog that is associated with increased LVM and impaired cardiac function. Inhibition of Endog in cultured cardiomyocytes resulted in an increase in cell size and hypertrophic biomarkers in the absence of pro-hypertrophic stimulation. Genome-wide network analysis unexpectedly implicated ENDOG in fundamental mitochondrial processes that are unrelated to apoptosis. We showed direct regulation of ENDOG by ERR-α and PGC1α (which are master regulators of mitochondrial and cardiac function), interaction of ENDOG with the mitochondrial genome and ENDOG-mediated regulation of mitochondrial mass. At baseline, the Endog-deleted mouse heart had depleted mitochondria, mitochondrial dysfunction and elevated levels of reactive oxygen species, which were associated with enlarged and steatotic cardiomyocytes. Our study has further established the link between mitochondrial dysfunction, reactive oxygen species and heart disease and has uncovered a role for Endog in maladaptive cardiac hypertrophy.
Nature 10/2011; 478(7367):114-8. · 36.28 Impact Factor
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Chris McDermott-Roe,
Junmei Ye,
Rizwan Ahmed,
Xi-Ming Sun,
Anna,
James Ware,
Leonardo Bottolo,
Phil Muckett,
Xavier,
Jisheng Zhang, [......],
Marisol Ruiz-Meana,
David,
Joan X. Comella,
Leanne E. Felkin,
Paul J. R. Barton,
Zoltan Arany, Michal Pravenec,
Enrico Petretto,
Daniel Sanchis,
Stuart A. Cook
Nature 10/2011; 478(7367):114-118. · 36.28 Impact Factor
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[show abstract]
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ABSTRACT: The spontaneously hypertensive rat (SHR) is a widely used rodent model of hypertension and metabolic syndrome. Previously we identified thousands of cis-regulated expression quantitative trait loci (eQTLs) across multiple tissues using a panel of rat recombinant inbred (RI) strains derived from Brown Norway and SHR progenitors. These cis-eQTLs represent potential susceptibility loci underlying physiological and pathophysiological traits manifested in SHR. We have prioritized 60 cis-eQTLs and confirmed differential expression between the parental strains by quantitative PCR in 43 (72%) of the eQTL transcripts. Quantitative trait transcript (QTT) analysis in the RI strains showed highly significant correlation between cis-eQTL transcript abundance and clinically relevant traits such as systolic blood pressure and blood glucose, with the physical location of a subset of the cis-eQTLs colocalizing with "physiological" QTLs (pQTLs) for these same traits. These colocalizing correlated cis-eQTLs (c3-eQTLs) are highly attractive as primary susceptibility loci for the colocalizing pQTLs. Furthermore, sequence analysis of the c3-eQTL genes identified single nucleotide polymorphisms (SNPs) that are predicted to affect transcription factor binding affinity, splicing and protein function. These SNPs, which potentially alter transcript abundance and stability, represent strong candidate factors underlying not just eQTL expression phenotypes, but also the correlated metabolic and physiological traits. In conclusion, by integration of genomic sequence, eQTL and QTT datasets we have identified several genes that are strong positional candidates for pathophysiological traits observed in the SHR strain. These findings provide a basis for the functional testing and ultimate elucidation of the molecular basis of these metabolic and cardiovascular phenotypes.
Physiological Genomics 08/2011; 43(21):1207-18. · 2.73 Impact Factor
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ABSTRACT: Disruption to the sensitive balance of long-chain fatty acids and glucose in the heart could cause cardiovascular diseases. Searching for a possible role of novel protein kinase C (nPKC) in heart with disrupted energy balance, we compared the insulin-resistant spontaneously hypertensive rats (SHR), which carry a nonfunctional variant of the fatty acid transporter FAT/CD36, with the less insulin-resistant congenic strain SHR-4 that is genetically identical except for a segment on chromosome 4 including a wild-type gene for a functional FAT/CD36. We analyzed expression of the nPKC-δ and -ε isoforms plus triacylglycerols (TAG) content in the myocardium of both FAT/CD36 strains and after a high sucrose diet (HSD). Two weeks before killing, males of both strains were randomly divided into two groups and fed either a standard laboratory chow or an HSD. PKC was determined by Western blotting in particulate and cytosolic fractions from left ventricles. The SHR-4 rats exhibited lower serum levels of insulin and free fatty acids than did SHR rats and higher amounts of PKC-ε in the heart particulate fraction. HSD caused accumulation of heart TAG in SHR but not in SHR-4. HSD increased PKC-δ and decreased PKC-ε expression in particulate fraction from left ventricles of SHR-4 while having no effects in SHR. These results demonstrate that reduced insulin resistance in SHR-4 rats with wild-type FAT/CD36 is associated with the insulin signaling pathway involving nPKCs.
Molecular and Cellular Biochemistry 05/2011; 357(1-2):163-9. · 2.06 Impact Factor
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Michal Pravenec,
Takashi Kajiya,
Václav Zídek,
Vladimír Landa,
Petr Mlejnek,
Miroslava Simáková,
Jan Silhavý,
Hana Malínská,
Olena Oliyarnyk,
Ludmila Kazdová,
Jianglin Fan,
Jiaming Wang,
Theodore W Kurtz
[show abstract]
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ABSTRACT: Major controversy exists as to whether increased C-reactive protein (CRP) contributes to individual components of the metabolic syndrome or is just a secondary response to inflammatory disease processes. We measured blood pressure and metabolic phenotypes in spontaneously hypertensive rats (SHRs) in which we transgenically expressed human CRP in the liver under control of the apolipoprotein E promoter. In transgenic SHRs, serum levels of human CRP approximated the endogenous levels of CRP normally found in the rat. Systolic and diastolic blood pressures measured by telemetry were 10 to 15 mm Hg greater in transgenic SHRs expressing human CRP than in SHR controls (P<0.01). During oral glucose tolerance testing, transgenic SHRs exhibited hyperinsulinemia compared with controls (insulin area under the curve: 36±7 versus 8±2 nmol/L per 2 hours, respectively; P<0.05). Transgenic SHRs also exhibited resistance to insulin stimulated glycogenesis in skeletal muscle (174±18 versus 278±32 nmol of glucose per gram per 2 hours; P<0.05), hypertriglyceridemia (0.84±0.05 versus 0.64±0.03 mmol/L; P<0.05), reduced serum adiponectin (2.4±0.3 versus 4.3±0.6 mmol/L; P<0.05), and microalbuminuria (200±35 versus 26±5 mg of albumin per gram of creatinine, respectively; P<0.001). Transgenic SHRs had evidence of inflammation and oxidative tissue damage with increased serum levels of interleukin 6 (36.4±5.2 versus 18±1.7 pg/mL; P<0.005) and increased hepatic and renal thiobarbituric acid reactive substances (1.2±0.09 versus 0.8±0.07 and 1.5±0.1 versus 1.1±0.05 nmol/L per milligram of protein, respectively; P<0.01), suggesting that oxidative stress may be mediating adverse effects of increased human CRP. These findings are consistent with the hypothesis that increased CRP is more than just a marker of inflammation and can directly promote multiple features of the metabolic syndrome.
Hypertension 02/2011; 57(4):731-7. · 6.21 Impact Factor
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Michal Pravenec,
Václav Zídek,
Vladimír Landa,
Miroslava Simáková,
Petr Mlejnek,
Jan Silhavy,
Martina Maxová,
Ludmila Kazdová,
Jonathan G Seidman,
Christine E Seidman,
Seda Eminaga,
Joshua Gorham,
Jiaming Wang,
Theodore W Kurtz
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ABSTRACT: Increased circulating levels of resistin have been proposed as a possible link between obesity and insulin resistance; however, many of the potential metabolic effects of resistin remain to be investigated, including systemic versus local resistin action. We investigated potential autocrine effects of resistin on lipid and glucose metabolism in 2- and 16-mo-old transgenic spontaneously hypertensive rats (SHR) expressing a nonsecreted form of mouse resistin under control of the aP2 promoter. To search for possible molecular mechanisms, we compared gene expression profiles in adipose tissue in 6-wk-old transgenic SHR versus control rats, before development of insulin resistance, by digital transcriptional profiling using high-throughput sequencing. Both young and old transgenic rats showed moderate expression of the resistin transgene in adipose tissue but had serum resistin levels similar to control SHR and undetectable levels of transgenic resistin in the circulation. Young transgenic rats exhibited mild glucose intolerance. In contrast, older transgenic rats displayed marked glucose intolerance in association with near total resistance of adipose tissue to insulin-stimulated glucose incorporation into lipids (6 ± 2 vs. 77 ± 19 nmol glucose·g(-1)·2 h(-1), P < 0.00001). Ingenuity Pathway Analysis of differentially expressed genes revealed calcium signaling, Nuclear factor-erythroid 2-related factor-2 (NRF2)-mediated oxidative stress response, and actin cytoskeletal signaling canonical pathways as those most significantly affected. Analysis using DAVID software revealed oxidative phosphorylation, glutathione metabolism, pyruvate metabolism, and peroxisome proliferator-activated receptor (PPAR) signaling as top Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. These results suggest that with increasing age autocrine effects of resistin in fat tissue may predispose to diabetes in part by impairing insulin action in adipose tissue.
Physiological Genomics 02/2011; 43(7):372-9. · 2.73 Impact Factor
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Petr Wohl,
Eva Krusinová,
Martin Hill,
Simona Kratochvílová,
Katerina Zídková,
Jan Kopecký,
Tomás Neskudla, Michal Pravenec,
Marta Klementová,
Jana Vrbíková,
Pavel Wohl,
Petr Mlejnek,
Terezie Pelikánová
[show abstract]
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ABSTRACT: Telmisartan improves glucose and lipid metabolism in rodents. This study evaluated the effect of telmisartan on insulin sensitivity, substrate utilization, selected plasma adipokines and their expressions in subcutaneous adipose tissue (SAT) in metabolic syndrome.
Twelve patients with impaired fasting glucose completed the double-blind, randomized, crossover trial. Patients received telmisartan (160 mg/day) or placebo for 3 weeks and vice versa with a 2-week washout period. At the end of each period, a hyperinsulinemic euglycemic clamp (HEC) combined with indirect calorimetry was performed. During HEC (0, 30, and 120 min), plasma levels of adipokines were measured and a needle biopsy (0 and 30 min) of SAT was performed.
Fasting plasma glucose was lower after telmisartan compared with placebo (P<0.05). There were no differences in insulin sensitivity and substrate utilization. We found no differences in basal plasma adiponectin, resistin and tumour necrosis factor α (TNFα), but an increase was found in basal leptin, after telmisartan treatment. Insulin-stimulated plasma adiponectin (P<0.05), leptin and resistin (P<0.001) were increased, whereas TNFα was decreased (P<0.05) after telmisartan treatment. Expression of resistin, but not adiponectin, TNFα and leptin was increased after telmisartan treatment.
Despite the decrease in fasting plasma glucose, telmisartan does not improve insulin sensitivity and substrate utilization. Telmisartan increases plasma leptin as well as insulin-stimulated plasma adiponectin, leptin and resistin, and decreases plasma TNFα during HEC. Changes in plasma adipokines cannot be explained by their expressions in SAT. The changes in plasma adipokines might be involved in the metabolic effects of telmisartan in metabolic syndrome.
European Journal of Endocrinology 10/2010; 163(4):573-83. · 3.42 Impact Factor
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Matthias Heinig,
Enrico Petretto,
Chris Wallace,
Leonardo Bottolo,
Maxime Rotival,
Han Lu,
Yoyo Li,
Rizwan Sarwar,
Sarah R Langley,
Anja Bauerfeind, [......],
Andreas Ziegler,
Laurence Tiret,
Deborah J Smyth, Michal Pravenec,
Timothy J Aitman,
Francois Cambien,
David Clayton,
John A Todd,
Norbert Hubner,
Stuart A Cook
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ABSTRACT: Combined analyses of gene networks and DNA sequence variation can provide new insights into the aetiology of common diseases that may not be apparent from genome-wide association studies alone. Recent advances in rat genomics are facilitating systems-genetics approaches. Here we report the use of integrated genome-wide approaches across seven rat tissues to identify gene networks and the loci underlying their regulation. We defined an interferon regulatory factor 7 (IRF7)-driven inflammatory network (IDIN) enriched for viral response genes, which represents a molecular biomarker for macrophages and which was regulated in multiple tissues by a locus on rat chromosome 15q25. We show that Epstein-Barr virus induced gene 2 (Ebi2, also known as Gpr183), which lies at this locus and controls B lymphocyte migration, is expressed in macrophages and regulates the IDIN. The human orthologous locus on chromosome 13q32 controlled the human equivalent of the IDIN, which was conserved in monocytes. IDIN genes were more likely to associate with susceptibility to type 1 diabetes (T1D)-a macrophage-associated autoimmune disease-than randomly selected immune response genes (P = 8.85 × 10(-6)). The human locus controlling the IDIN was associated with the risk of T1D at single nucleotide polymorphism rs9585056 (P = 7.0 × 10(-10); odds ratio, 1.15), which was one of five single nucleotide polymorphisms in this region associated with EBI2 (GPR183) expression. These data implicate IRF7 network genes and their regulatory locus in the pathogenesis of T1D.
Nature 09/2010; 467(7314):460-4. · 36.28 Impact Factor
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Santosh S Atanur,
Inanç Birol,
Victor Guryev,
Martin Hirst,
Oliver Hummel,
Catherine Morrissey,
Jacques Behmoaras,
Xose M Fernandez-Suarez,
Michelle D Johnson,
William M McLaren, [......],
Yongjun Zhao,
Piero Carninci,
Paul Flicek,
Ted Kurtz,
Edwin Cuppen, Michal Pravenec,
Norbert Hubner,
Steven J M Jones,
Ewan Birney,
Timothy J Aitman
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ABSTRACT: The spontaneously hypertensive rat (SHR) is the most widely studied animal model of hypertension. Scores of SHR quantitative loci (QTLs) have been mapped for hypertension and other phenotypes. We have sequenced the SHR/OlaIpcv genome at 10.7-fold coverage by paired-end sequencing on the Illumina platform. We identified 3.6 million high-quality single nucleotide polymorphisms (SNPs) between the SHR/OlaIpcv and Brown Norway (BN) reference genome, with a high rate of validation (sensitivity 96.3%-98.0% and specificity 99%-100%). We also identified 343,243 short indels between the SHR/OlaIpcv and reference genomes. These SNPs and indels resulted in 161 gain or loss of stop codons and 629 frameshifts compared with the BN reference sequence. We also identified 13,438 larger deletions that result in complete or partial absence of 107 genes in the SHR/OlaIpcv genome compared with the BN reference and 588 copy number variants (CNVs) that overlap with the gene regions of 688 genes. Genomic regions containing genes whose expression had been previously mapped as cis-regulated expression quantitative trait loci (eQTLs) were significantly enriched with SNPs, short indels, and larger deletions, suggesting that some of these variants have functional effects on gene expression. Genes that were affected by major alterations in their coding sequence were highly enriched for genes related to ion transport, transport, and plasma membrane localization, providing insights into the likely molecular and cellular basis of hypertension and other phenotypes specific to the SHR strain. This near complete catalog of genomic differences between two extensively studied rat strains provides the starting point for complete elucidation, at the molecular level, of the physiological and pathophysiological phenotypic differences between individuals from these strains.
Genome Research 06/2010; 20(6):791-803. · 13.61 Impact Factor
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ABSTRACT: The spontaneously hypertensive rat (SHR) is the most widely used animal model of essential hypertension and associated metabolic disturbances. Multiple quantitative trait loci associated with hemodynamic and metabolic parameters have been mapped in the SHR. Recently, it has become possible to identify some of the specific quantitative trait gene (QTG) variants that underlie quantitative trait loci linked to complex cardiovascular and metabolic traits in SHR related strains. Recombinant inbred strains derived from SHR and Brown Norway progenitors, together with SHR congenic and transgenic strains, have proven useful for establishing the identity of several QTGs in SHR models. It is anticipated that the combined use of linkage analyses and gene expression profiles, together with the recently available genome sequences of both the SHR and Brown Norway strains and new methods for manipulating the rat genome, will soon accelerate progress in identifying QTGs for complex traits in SHR-related strains.
Current Hypertension Reports 02/2010; 12(1):5-9. · 2.50 Impact Factor
