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Circulating microRNAs and hypertension - From new insights into blood pressure regulation to biomarkers of cardiovascular risk

- Romaine, Simon, Charchar, Fadi, Samani, Nilesh, Tomaszewski, Maciej

  • Authors: Romaine, Simon , Charchar, Fadi , Samani, Nilesh , Tomaszewski, Maciej
  • Date: 2016
  • Type: Text , Journal article
  • Relation: Current Opinion in Pharmacology Vol. 27, no. (2016), p. 1-7
  • Relation: http://purl.org/au-research/grants/nhmrc/1009490
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  • Description: Hypertension is a leading cause of cardiovascular morbidity and mortality worldwide, yet the molecular mechanisms underpinning the development of high blood pressure remain incompletely understood. MicroRNAs are small, non-coding RNA molecules approximately 22 nucleotides in length that act as post-transcriptional regulators of gene expression. We highlight, through a review of recent literature, that studies on circulating microRNAs have provided novel insights into blood pressure regulation. They have also complemented tissue-based and animal-based experiments in shedding new light on our understanding of established pathways in hypertension, such as the renin-angiotensin system. Despite a number of challenges, we believe microRNAs herald particular potential in becoming effective biomarkers of target-organ damage in hypertension. © 2016 Elsevier Ltd. All rights reserved.

Coronary artery disease : Why we should consider the Y chromosome

- Molina, Elsa, Clarence, Elyse, Ahmady, Farah, Chew, Guatsiew, Charchar, Fadi

  • Authors: Molina, Elsa , Clarence, Elyse , Ahmady, Farah , Chew, Guatsiew , Charchar, Fadi
  • Date: 2016
  • Type: Text , Journal article , Review
  • Relation: Heart Lung and Circulation Vol. 25, no. 8 (Aug 2016), p. 791-801
  • Relation: http://purl.org/au-research/grants/nhmrc/1009490
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  • Description: Coronary artery disease (CAD) is one of the leading causes of morbidity and mortality globally. In the last few years our understanding of the genetic and molecular mechanisms that promote CAD in individuals has increased with the advent of the genome era. This complex inflammatory disease has well-defined environmental risk factors. However, in the last 10 years, studies including genome-wide association studies (GWAS) have clearly demonstrated a genetic influence on CAD. Recently, studies on the human Y chromosome have also demonstrated that genetic variation within the male-specific region of the Y chromosome (MSY) could play a part in determining cardiovascular risk in men, confirming the notion that the increased risk for CAD in men cannot be fully explained through common CAD risk factors. Here, we review the literature about the pathophysiology of CAD, its potential causes and environmental risk factors known so far. Furthermore, we review the genetics of CAD, especially the latest discoveries regarding the implication of the Y chromosome, the most underexplored portion of the human genome to date, highlighting methods and difficulties arising in this research field, and discussing the importance of considering the Y chromosome in CAD research.

Epigenetic changes in leukocytes after 8 weeks of resistance exercise training

- Denham, Joshua, Marques, Francine, Bruns, Emma, O'Brien, Brendan, Charchar, Fadi

  • Authors: Denham, Joshua , Marques, Francine , Bruns, Emma , O'Brien, Brendan , Charchar, Fadi
  • Date: 2016
  • Type: Text , Journal article
  • Relation: European Journal of Applied Physiology Vol. 116, no. 6 (2016), p. 1245-1253
  • Relation: http://purl.org/au-research/grants/nhmrc/1009490
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  • Description: PURPOSE: Regular engagement in resistance exercise training elicits many health benefits including improvement to muscular strength, hypertrophy and insulin sensitivity, though the underpinning molecular mechanisms are poorly understood. The purpose of this study was to determine the influence 8 weeks of resistance exercise training has on leukocyte genome-wide DNA methylation and gene expression in healthy young men. METHODS: Eight young (21.1 +/- 2.2 years) men completed one repetition maximum (1RM) testing before completing 8 weeks of supervised, thrice-weekly resistance exercise training comprising three sets of 8-12 repetitions with a load equivalent to 80 % of 1RM. Blood samples were collected at rest before and after the 8-week training intervention. Genome-wide DNA methylation and gene expression were assessed on isolated leukocyte DNA and RNA using the 450K BeadChip and HumanHT-12 v4 Expression BeadChip (Illumina), respectively. RESULTS: Resistance exercise training significantly improved upper and lower body strength concurrently with diverse genome-wide DNA methylation and gene expression changes (p

Epigenetic modifications in essential hypertension

- Wise, Ingrid, Charchar, Fadi

  • Authors: Wise, Ingrid , Charchar, Fadi
  • Date: 2016
  • Type: Text , Journal article , Review
  • Relation: International Journal of Molecular Sciences Vol. 17, no. 4 (2016), p. 1-14
  • Relation: http://purl.org/au-research/grants/nhmrc/1009490
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  • Description: Essential hypertension (EH) is a complex, polygenic condition with no single causative agent. Despite advances in our understanding of the pathophysiology of EH, hypertension remains one of the world’s leading public health problems. Furthermore, there is increasing evidence that epigenetic modifications are as important as genetic predisposition in the development of EH. Indeed, a complex and interactive genetic and environmental system exists to determine an individual’s risk of EH. Epigenetics refers to all heritable changes to the regulation of gene expression as well as chromatin remodelling, without involvement of nucleotide sequence changes. Epigenetic modification is recognized as an essential process in biology, but is now being investigated for its role in the development of specific pathologic conditions, including EH. Epigenetic research will provide insights into the pathogenesis of blood pressure regulation that cannot be explained by classic Mendelian inheritance. This review concentrates on epigenetic modifications to DNA structure, including the influence of non-coding RNAs on hypertension development. © 2016 by the authors; licensee MDPI, Basel, Switzerland.

Genetic associations at 53 loci highlight cell types and biological pathways relevant for kidney function

- Pattaro, C, Teumer, A, Gorski, M, Chu, A.Y., Li, M, Mijatovic, V, Garnaas, M, Tin, A, Charchar, Fadi

  • Authors: Pattaro, C , Teumer, A , Gorski, M , Chu, A.Y. , Li, M , Mijatovic, V , Garnaas, M , Tin, A , Charchar, Fadi
  • Date: 2016
  • Type: Text , Journal article
  • Relation: Nature Communications Vol. 7, no. (2016), p. 1-19
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  • Description: Reduced glomerular filtration rate defines chronic kidney disease and is associated with cardiovascular and all-cause mortality. We conducted a meta-analysis of genome-wide association studies for estimated glomerular filtration rate (eGFR), combining data across 133,413 individuals with replication in up to 42,166 individuals. We identify 24 new and confirm 29 previously identified loci. Of these 53 loci, 19 associate with eGFR among individuals with diabetes. Using bioinformatics, we show that identified genes at eGFR loci are enriched for expression in kidney tissues and in pathways relevant for kidney development and transmembrane transporter activity, kidney structure, and regulation of glucose metabolism. Chromatin state mapping and DNase I hypersensitivity analyses across adult tissues demonstrate preferential mapping of associated variants to regulatory regions in kidney but not extra-renal tissues. These findings suggest that genetic determinants of eGFR are mediated largely through direct effects within the kidney and highlight important cell types and biological pathways. © 2016, Nature Publishing Group. All rights reserved. Please note that there are two hundred and six authors for this article and we have included only the Federation University Australia affiliate.

Telomere dynamics during aging in polygenic left ventricular hypertrophy

- Marques, Francine, Booth, Scott, Prestes, Priscilla, Curl, Claire, Delbridge, Lea, Lewandowski, Paul, Harrap, Stephen, Charchar, Fadi

  • Authors: Marques, Francine , Booth, Scott , Prestes, Priscilla , Curl, Claire , Delbridge, Lea , Lewandowski, Paul , Harrap, Stephen , Charchar, Fadi
  • Date: 2016
  • Type: Text , Journal article
  • Relation: Physiological Genomics Vol. 48, no. 1 (2016), p. 42-49
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  • Description: Short telomeres are associated with increased risk of cardiovascular disease. Here we studied cardiomyocyte telomere length at key ages during the ontogeny of cardiac hypertrophy and failure in the hypertrophic heart rat (HHR) and compared these with the normal heart rat (NHR) control strain. Key ages corresponded with the pathophysiological sequence beginning with fewer cardiomyocytes (2 days), leading to left ventricular hypertrophy (LVH) (13 wk) and subsequently progression to heart failure (38 wk). We measured telomere length, tissue activity of telomerase, mRNA levels of telomerase reverse transcriptase (Tert) and telomerase RNA component (Terc), and expression of the telomeric regulator microRNA miR-34a. Cardiac telomere length was longer in the HHR compared with the control strain at 2 days and 38 wk, but shorter at 13 wk. Neonatal HHR had higher cardiac telomerase activity and expression of Tert and miR-34a. Telomerase activity was not different at 13 or 38 wk. Tert mRNA and Terc RNA were overexpressed at 38 wk, while miR-34a was overexpressed at 13 wk but downregulated at 38 wk. Circulating leukocytes were strongly correlated with cardiac telomere length in the HHR only. The longer neonatal telomeres in HHR are likely to reflect fewer fetal and early postnatal cardiomyocyte cell divisions and explain the reduced total cardiomyocyte complement that predisposes to later hypertrophy and failure. Although shorter telomeres were a feature of cardiac hypertrophy at 13 wk, they were not present at the progression to heart failure at 38 wk. © 2016 the American Physiological Society.

Telomere length maintenance and cardio-metabolic disease prevention through exercise training

- Denham, Joshua, O'Brien, Brendan, Charchar, Fadi

  • Authors: Denham, Joshua , O'Brien, Brendan , Charchar, Fadi
  • Date: 2016
  • Type: Text , Journal article , Review
  • Relation: Sports Medicine Vol. 46, no. 9 (2016), p. 1213-1237
  • Relation: http://purl.org/au-research/grants/nhmrc/1009490
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  • Description: Telomeres are tandem repeat DNA sequences located at distal ends of chromosomes that protect against genomic DNA degradation and chromosomal instability. Excessive telomere shortening leads to cellular senescence and for this reason telomere length is a marker of biological age. Abnormally short telomeres may culminate in the manifestation of a number of cardio-metabolic diseases. Age-related cardio-metabolic diseases attributable to an inactive lifestyle, such as obesity, type 2 diabetes mellitus and cardiovascular disease, are associated with short leukocyte telomeres. Exercise training prevents and manages the symptoms of many cardio-metabolic diseases whilst concurrently maintaining telomere length. The positive relationship between exercise training, physical fitness and telomere length raises the possibility of a mediating role of telomeres in chronic disease prevention via exercise. Further elucidation of the underpinning molecular mechanisms of how exercise maintains telomere length should provide crucial information on how physical activity can be best structured to combat the chronic disease epidemic and improve the human health span. Here, we synthesise and discuss the current evidence on the impact of physical activity and cardiorespiratory fitness on telomere dynamics. We provide the molecular mechanisms with a known role in exercise-induced telomere length maintenance and highlight unexplored, alternative pathways ripe for future investigations.

Tripartite motif-containing 55 identified as functional candidate for spontaneous cardiac hypertrophy in the rat locus cardiac mass 22

- Prestes, Priscilla, Marques, Francine, Lopez-Campos, Guillermo, Booth, Scott, McGlynn, Maree, Lewandowski, Paul, Delbridge, Lea, Harrap, Stephen, Charchar, Fadi

  • Authors: Prestes, Priscilla , Marques, Francine , Lopez-Campos, Guillermo , Booth, Scott , McGlynn, Maree , Lewandowski, Paul , Delbridge, Lea , Harrap, Stephen , Charchar, Fadi
  • Date: 2016
  • Type: Text , Journal article
  • Relation: Journal of Hypertension Vol. 34, no. 5 (May 2016), p. 950-958
  • Relation: http://purl.org/au-research/grants/nhmrc/1034371
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  • Description: Background:Left ventricular (LV) hypertrophy is a risk factor for cardiovascular death, but the genetic factors determining LV size and predisposition to hypertrophy are not well understood. We have previously linked the quantitative trait locus cardiac mass 22 (Cm22) on chromosome 2 with cardiac hypertrophy independent of blood pressure in the spontaneously hypertensive rat. From an original cross of spontaneously hypertensive rat with F344 rats, we derived a normotensive polygenic model of spontaneous cardiac hypertrophy, the hypertrophic heart rat (HHR) and its control strain, the normal heart rat (NHR).Methods and results:To identify the genes and molecular mechanisms underlying spontaneous LV hypertrophy we sequenced the HHR genome with special focus on quantitative trait locus Cm22. For correlative analyses of function, we measured global RNA transcripts in LV of neonatal HHR and NHR and 198 neonatal rats of an HHRxNHR F2 crossbred population. Only one gene within locus Cm22 was differentially expressed in the parental generation: tripartite motif-containing 55 (Trim55), with mRNA downregulation in HHR (P<0.05) and reduced protein expression. Trim55 mRNA levels were negatively correlated with LV mass in the F2 cross (r=-0.16, P=0.025). In exon nine of Trim55 in HHR, we found one missense mutation that functionally alters protein structure. This mutation was strongly associated with Trim55 mRNA expression in F2 rats (F=10.35, P<0.0001). Similarly, in humans, we found reduced Trim55 expression in hearts of subjects with idiopathic dilated cardiomyopathy.Conclusion:Our study suggests that the Trim55 gene, located in Cm22, is a novel candidate gene for polygenic LV hypertrophy independent of blood pressure.

A meta-analysis of gene expression signatures of blood pressure and hypertension

- Charchar, Fadi

  • Authors: Charchar, Fadi
  • Date: 2015
  • Type: Text , Journal article
  • Relation: PLoS Genetics Vol. 11, no. 3 (2015), p. 1-29
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  • Description: Genome-wide association studies (GWAS) have uncovered numerous genetic variants (SNPs) that are associated with blood pressure (BP). Genetic variants may lead to BP changes by acting on intermediate molecular phenotypes such as coded protein sequence or gene expression, which in turn affect BP variability. Therefore, characterizing genes whose expression is associated with BP may reveal cellular processes involved in BP regulation and uncover how transcripts mediate genetic and environmental effects on BP variability. A meta-analysis of results from six studies of global gene expression profiles of BP and hypertension in whole blood was performed in 7017 individuals who were not receiving antihypertensive drug treatment. We identified 34 genes that were differentially expressed in relation to BP (Bonferroni-corrected p<0.05). Among these genes, FOS and PTGS2 have been previously reported to be involved in BP-related processes; the others are novel. The top BP signature genes in aggregate explain 5%–9% of inter-individual variance in BP. Of note, rs3184504 in SH2B3, which was also reported in GWAS to be associated with BP, was found to be a trans regulator of the expression of 6 of the transcripts we found to be associated with BP (FOS, MYADM, PP1R15A, TAGAP, S100A10, and FGBP2). Gene set enrichment analysis suggested that the BP-related global gene expression changes include genes involved in inflammatory response and apoptosis pathways. Our study provides new insights into molecular mechanisms underlying BP regulation, and suggests novel transcriptomic markers for the treatment and prevention of hypertension. **Please note that there are multiple authors for this article therefore only the name of the Federation University Australia affiliate is provided in this record**

A multi-omics glimpse into the biology of arterial stiffness

- Eales, James, Romaine, Simon, Charchar, Fadi, Tomaszewski, Maciej

  • Authors: Eales, James , Romaine, Simon , Charchar, Fadi , Tomaszewski, Maciej
  • Date: 2015
  • Type: Text , Journal article
  • Relation: Journal of Hypertension Vol. 34, no. 1 (2015), p. 32-35
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  • Description: It has long been recognized that the structure of arteries throughout the vascular tree is not uniform. Notably, the media of large proximal (central) vessels contains relatively much greater amounts of elastin and elastic lamellae than smaller, more distal (peripheral) arteries; the converse is true of vascular smooth muscle cells. Under physiological conditions, the greater elasticity of central arteries compared with more muscular peripheral arteries allows conversion of the pulsatile nature of ventricular ejection into a relatively steady flow of blood at the distal end of the arterial system, conferring protection from pulsatile energy [1,2]. Furthermore, these differences in impedance can generate partial wave reflections, which arrive in the aorta during diastole, boosting diastolic blood pressure and augmenting coronary perfusion pressure [3].

Changes in the leukocyte methylome and its effect on cardiovascular-related genes after exercise

- Denham, Joshua, O'Brien, Brendan, Marques, Francine, Charchar, Fadi

  • Authors: Denham, Joshua , O'Brien, Brendan , Marques, Francine , Charchar, Fadi
  • Date: 2015
  • Type: Text , Journal article
  • Relation: Journal of Applied Physiology Vol. 118, no. 4 (2015), p. 475-488
  • Relation: http://purl.org/au-research/grants/nhmrc/1009490
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  • Description: Physical exercise has proven cardiovascular benefits, yet there is no clear understanding of the related molecular mechanisms leading to this. Here we determined the beneficial epigenetic effects of exercise after sprint interval training, a form of exercise known to improve cardiometabolic health. We quantified genome-wide leukocyte DNA methylation of 12 healthy young (18-24 yr) men before and after 4 wk (thrice weekly) of sprint interval training using the 450K BeadChip (Illumina) and validated gene expression changes in an extra seven subjects. Exercise increased subjects' cardiorespiratory fitness and maximal running performance, and decreased low-density lipoprotein cholesterol concentration in conjunction with genome-wide DNA methylation changes. Notably, many CpG island and gene promoter regions were demethylated after exercise, indicating increased genome-wide transcriptional changes. Among genes with DNA methylation changes, epidermal growth factor (EGF), a ligand of the epidermal growth factor receptor known to be involved in cardiovascular disease, was demethylated and showed decreased mRNA expression. Additionally, we found that in microRNAs miR-21 and miR-210, gene DNA methylation was altered by exercise causing a cascade effect on the expression of the mature microRNA involved in cardiovascular function. Our findings demonstrate that exercise alters DNA methylation in circulating blood cells in microRNA and protein-coding genes associated with cardiovascular physiology. Copyright © 2015 the American Physiological Society

Contribution of microRNA to pathological fibrosis in cardiorenal syndrome : Impact of uremic toxins

- Rana, Indrajeetsinh, Kompa, Andrew, Skommer, Joanna, Wang, Bing, Lekawanvijit, Suree, Kelly, Darren, Krum, Henry, Charchar, Fadi

  • Authors: Rana, Indrajeetsinh , Kompa, Andrew , Skommer, Joanna , Wang, Bing , Lekawanvijit, Suree , Kelly, Darren , Krum, Henry , Charchar, Fadi
  • Date: 2015
  • Type: Text , Journal article
  • Relation: Physiological Reports Vol. 3, no. 4 (2015), p. 1-15
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  • Description: Progressive reduction in kidney function in patients following myocardial infarction (MI) is associated with an increase in circulating uremic toxins levels leading to increased extracellular matrix deposition. We have recently reported that treatment with uremic toxin adsorbent AST-120 in rats with MI inhibits serum levels of uremic toxin indoxyl sulfate (IS) and downregulates expression of cardiac profibrotic cytokine transforming growth factor beta (TGF-β1). In this study, we examined the effect of uremic toxins post-MI on cardiac microRNA-21 and microRNA-29b expression, and also the regulation of target genes and matrix remodeling proteins involved in TGFβ1 and angiotensin II signaling pathways. Sixteen weeks after MI, cardiac tissues were assessed for pathological and molecular changes. The percentage area of cardiac fibrosis was 4.67 ± 0.17 in vehicle-treated MI, 2.9 ± 0.26 in sham, and 3.32 ± 0.38 in AST-120-treated MI, group of rats. Compared to sham group, we found a twofold increase in the cardiac expression of microRNA-21 and 0.5-fold decrease in microRNA-29b in heart tissue from vehicle-treated MI. Treatment with AST-120 lowered serum IS levels and attenuated both, cardiac fibrosis and changes in expression of these microRNAs observed after MI. We also found increased mRNA expression of angiotensin-converting enzyme (ACE) and angiotensin receptor 1a (Agtr1a) in cardiac tissue collected from MI rats. Treatment with AST-120 attenuated both, expression of ACE and Agtr1a mRNA. Exposure of rat cardiac fibroblasts to IS upregulated angiotensin II signaling and altered the expression of both microRNA-21 and micro- RNA-29b. These results collectively suggest a clear role of IS in altering microRNA-21 and microRNA-29b in MI heart, via a mechanism involving angiotensin signaling pathway, which leads to cardiac fibrosis. © 2015 The Authors.

Dysregulation of c-kit expression parallels the development of spontaneous genetic cardiac hypertrophy

- Marques, Francine, Prestes, Priscilla, Lewandowski, Paul, Harrap, Stephen, Charchar, Fadi

  • Authors: Marques, Francine , Prestes, Priscilla , Lewandowski, Paul , Harrap, Stephen , Charchar, Fadi
  • Date: 2015
  • Type: Text , Conference paper
  • Relation: Cardiac Society of Australia and New Zealand Annual Scientific Meeting and the International Society for Heart Research Australasian Section Annual Scientific Meeting; Melbourne, Victoria, Australia; 13th-16th August 2016; published in Heart, Lung and Circulation. Vol. 24, p. S401-S401
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  • Description: Objective: The molecular processes associated with cardiac hypertrophy independent of blood pressure are still largely unknown. The hypertrophic heart rate (HHR) is normotensive and born with a reduced complement of cardiomyocytes that predisposes to cardiac hypertrophy and failure in later life. We investigated the expression of c-kit gene, a marker of cardiac stem cells and myocardial regeneration that could contribute to hypertrophy. Methods: Left ventricular c-kit mRNA expression was measured by real-time PCR in HHR and control strain in neonatal and 38-week old rats (n=7-12/group). We tested for linkage of c-kit expression with neonatal cardiac size in 197 second generation crosses (F2) of HHR and control strain. Results: c-kit mRNA was slightly up-regulated in neonatal (fold change +1.3, P=0.02) and markedly so in 38-week old HHR (+35.5, P=0.0003). Cardiac weight index was positively correlated with neonatal myocardial c-kit mRNA in the F2 population (r=0.19, P=0.007). Conclusions: In HHR hearts c-kit expression appears increased throughout life, but more so in the adult where cardiac hypertrophy is established and leading to failure. In aged hypertrophic hearts, over-expression of c-kit is likely a compensatory mechanism of the failing heart. Previous studies showed an activation of cardiac stem cells in the hypertrophic myocardium. Our study suggests that c-kit might be involved from an early age in mechanisms that lead to cardiac hypertrophy in adulthood.

Genome-wide sperm DNA methylation changes after 3 months of exercise training in humans

- Denham, Joshua, O'Brien, Brendan, Harvey, Jack, Charchar, Fadi

  • Authors: Denham, Joshua , O'Brien, Brendan , Harvey, Jack , Charchar, Fadi
  • Date: 2015
  • Type: Text , Journal article
  • Relation: Epigenomics Vol. 7, no. 5 (2015), p. 717-731
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  • Description: Aim: DNA methylation programs gene expression and is involved in numerous biological processes. Accumulating evidence supports transgenerational inheritance of DNA methylation changes in mammals via germ cells. Our aim was to determine the effect of exercise on sperm DNA methylation. Materials & methods: Twenty-four men were recruited and assigned to an exercise intervention or control group. Clinical parameters were measured and sperm samples were donated by subjects before and after the 3-month time-period. Mature sperm global and genome-wide DNA methylation was assessed using an ELISA assay and the 450K BeadChip (Illumina). Results: Global and genome-wide sperm DNA methylation was altered after 3 months of exercise training. DNA methylation changes occurred in genes related to numerous diseases such as schizophrenia and Parkinson's disease. Conclusions: Our study provides the first evidence showing exercise training reprograms the sperm methylome. Whether these DNA methylation changes are inherited to future generations warrants attention.

Increased expression of telomere-regulating genes in endurance athletes with long leukocyte telomeres

- Denham, Joshua, O'Brien, Brendan, Prestes, Priscilla, Brown, Nicholas, Charchar, Fadi

  • Authors: Denham, Joshua , O'Brien, Brendan , Prestes, Priscilla , Brown, Nicholas , Charchar, Fadi
  • Date: 2015
  • Type: Text , Journal article
  • Relation: Journal of Applied Physiology Vol. 120, no. 2 (2015), p. 148-158
  • Relation: http://purl.org/au-research/grants/nhmrc/1009490
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  • Description: Leukocyte telomeres shorten with age, and excessive shortening is associated with age-related cardiometabolic diseases. Exercise training may prevent disease through telomere length maintenance although the optimal amount of exercise that attenuates telomere attrition is unknown. Furthermore, the underlying molecular mechanisms responsible for the enhanced telomere maintenance observed in endurance athletes is poorly understood. We quantified the leukocyte telomere length and analyzed the expression of telomere-regulating genes in endurance athletes and healthy controls (both n = 61), using quantitative PCR. We found endurance athletes have significantly longer (7.1%, 208-416 nt) leukocyte telomeres and upregulated TERT (2.0-fold) and TPP1 (1.3-fold) mRNA expression compared with controls in age-adjusted analysis. The telomere length and telomere-regulating gene expression differences were no longer statistically significant after adjustment for resting heart rate and relative (V) over dotO(2 max) (all P > 0.05). Resting heart rate emerged as an independent predictor of leukocyte telomere length and TERT and TPP1 mRNA expression in stepwise regression models. To gauge whether volume of exercise was associated with leukocyte telomere length, we divided subjects into running and cycling tertiles (distance covered per week) and found individuals in the middle and highest tertiles had longer telomeres than individuals in the lowest tertile. These data emphasize the importance of cardiorespiratory fitness and exercise training in the prevention of biological aging. They also support the concept that moderate amounts of exercise training protects against biological aging, while higher amounts may not elicit additional benefits.

MicroRNA-34a and tert act as epi-drivers of cardiac telomere length and polygenic cardiac hypertrophy

- Booth, Scott, Marques, Francine, Prestes, Priscilla, Curl, Claire, Delbridge, Lea, Lewandowski, Paul, Harrap, Stephen, Charchar, Fadi

  • Authors: Booth, Scott , Marques, Francine , Prestes, Priscilla , Curl, Claire , Delbridge, Lea , Lewandowski, Paul , Harrap, Stephen , Charchar, Fadi
  • Date: 2015
  • Type: Text , Journal article
  • Relation: Heart, Lung and Circulation Vol. 24, no. S3 (2015), p. S180-S181
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  • Description: Cardiac hypertrophy is one of the main risk factors forheart failure. Here we aimed to investigate whether cardiactelomere length contributes to polygenic cardiac hypertro-phy independent of blood pressure. We also investigatedwhether changes in telomere length were due to the telomereregulators microRNA-34a,Ppp1r10(also known asPnuts)and telomerase. We used the hypertrophic heart rat (HHR),a normotensive model of polygenetic cardiac hypertrophy,and compared it to age-matched controls. Telomere length, microRNA levels, gene expression and telomerase activitywere measured in isolated cardiomyocytes and left ventricletissue using real-time PCR. Telomere length was significantlylonger in 2-day and 38-week-old HHR, but shorter at 4-and 13-week HHR. In the HHR, telomere length becameshorter early in development, while in the control straintelomere shortening was only observed in late adulthood.Telomere length was the main determinant of cardiac mass.

MicroRNAs in essential hypertension and blood pressure regulation

- Marques, Francine, Charchar, Fadi

  • Authors: Marques, Francine , Charchar, Fadi
  • Date: 2015
  • Type: Text , Book chapter
  • Relation: Advances in Experimental Medicine and Biology p. 215-235
  • Relation: http://purl.org/au-research/grants/nhmrc/1009490
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  • Description: Unravelling the complete genetic predisposition to high blood pressure (BP) has proven to be challenging. This puzzle and the fact that coding regions of the genome account for less than 2 % of the entire human DNA support the hypothesis that mechanisms besides coding genes are likely to contribute to BP regulation. Non-coding RNAs, especially microRNAs, are emerging as key players of transcription regulation in both health and disease states. They control basic functions in virtually all cell types relevant to the cardiovascular system and, thus, a direct involvement with BP regulation is highly probable. Here we review the literature about microRNAs associated with regulation of BP and hypertension, highlighting investigations, methodology and difficulties arising in the field. These molecules are being studied for exploitation in diagnostics, prognostics and therapeutics in many diseases. There have been some studies that examined biological fl uid microRNAs as biomarkers for hypertension, but most remain inconclusive due to the small sample sizes and differences in methodological standardisation. Fewer studies have analysed tissue microRNA levels in vascular smooth muscle cells and the kidney. Others focused on the interaction between single nucleotide polymorphisms and microRNA binding sites. Studies in animals have shown that angiotensin II, high- salt diet and exercise change microRNA levels in hypertension. Treatment of spontaneously hypertensive rats with a miR-22 inhibitor and treatment of hypertensive Schlager BPH/2J mice with a miR-181a mimic decreased their BP. This supports the use of microRNAs as therapeutic targets in hypertension, and future studies should test the use of other microRNAs found in human association studies. In conclusion, there is a clear need of increased pace of human, animal and functional studies to help us understand the multifaceted roles of microRNAs as critical regulators of the development and physiology of BP. © Springer International Publishing Switzerland 2015. Funding Details: APP1052659, NHMRC, National Heart Foundation of Australia Funding Details: PF12M6785, National Heart Foundation of Australia

MicroRNAs mediate the cardioprotective effect of angiotensin-converting enzyme inhibition in acute kidney injury

- Rana, Indrajeetsinh, Velkoska, Elena, Patel, Sheila, Burrell, Louise, Charchar, Fadi

  • Authors: Rana, Indrajeetsinh , Velkoska, Elena , Patel, Sheila , Burrell, Louise , Charchar, Fadi
  • Date: 2015
  • Type: Text , Journal article
  • Relation: American Journal of Physiology - Renal Physiology Vol. 309, no. 11 (2015), p. F943-F954
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  • Description: Cardiovascular disease, including cardiac hypertrophy, is common in patients with kidney disease and can be partially attenuated using blockers of the renin-angiotensin system (RAS). It is unknown whether cardiac microRNAs contribute to the pathogenesis of cardiac hypertrophy or to the protective effect of RAS blockade in kidney disease. Using a subtotal nephrectomy rat model of kidney injury, we investigated changes in cardiac microRNAs that are known to have direct target genes involved in the regulation of apoptosis, fibrosis, and hypertrophy. The effect of treatment with the angiotensin-converting enzyme (ACE) inhibitor ramipril on cardiac microRNAs was also investigated. Kidney injury led to a significant increase in cardiac microRNA-212 and mi- croRNA-132 expression. Ramipril reduced cardiac hypertrophy, attenuated the increase in microRNA-212 and microRNA-132, and significantly increased microRNA-133 and microRNA-1 expression. There was altered expression of caspase-9, B cell lymphoma-2, transforming growth factor-β, fibronectin 1, collagen type 1A1, and forkhead box protein O3, which are all known to be involved in the regulation of apoptosis, fibrosis, and hypertrophy in cardiac cells while being targets for the above microRNAs. ACE inhibitor treatment increased expression of microRNA-133 and microRNA-1. The inhibitory action of ACE inhibitor treatment on increased cardiac NADPH oxidase isoform 1 expression after subtotal nephrectomy surgery suggests that inhibition of oxidative stress is also one of mechanism of ACE inhibitor-mediated cardioprotection. These finding suggests the involvement of microRNAs in the cardioprotective action of ACE inhibition in acute renal injury, which is mediated through an inhibitory action on profibrotic and proapoptotic target genes and stimulatory action on antihypertrophic and antiapoptotic target genes. © 2015 the American Physiological Society. Funding: APP1048285; NHMRC; National Health and Medical Research Council

Renal Mechanisms of Association between Fibroblast Growth Factor 1 and Blood Pressure

- Tomaszewski, Maciej, Eales, James, Denniff, Matthew, Myers, Stephen, Chew, Guatsiew, Nelson, Christopher, Christofidou, Paraskevi, Desai, Aishwarya, Büsst, Cara, Wojnar, Lukasz, Musialik, Katarzyna, Jozwiak, Jacek, Debiec, Radoslaw, Dominiczak, Anna, Navis, Gerjan, van Gilst, Wiek, van der Harst, Pim, Samani, Nilesh, Harrap, Stephen, Bogdanski, Pawel, Zukowska-Szczechowska, Ewa, Charchar, Fadi

Runs of Homozygosity : Association with Coronary Artery Disease and Gene Expression in Monocytes and Macrophages

- Christofidou, Paraskevi, Nelson, Christopher, Nikpay, Majid, Qu, Liming, Li, Mingyao, Loley, Christina, Debiec, Radoslaw, Braund, Peter, Denniff, Matthew, Charchar, Fadi, Arjo, Ares Rocanin, Trégouët, David-Alexandre, Goodall, Alison, Cambien, Francois, Ouwehand, Willem, Roberts, Robert, Schunkert, Heribert, Hengstenberg, Christian, Reilly, Muredach, Erdmann, Jeanette, McPherson, Ruth, König, Inke, Thompson, John, Samani, Nilesh, Tomaszewski, Maciej