Publications by authors named "Elizabeth J Cartwright"

70 Publications

Plasma membrane calcium ATPase 1 regulates human umbilical vein endothelial cell angiogenesis and viability.

J Mol Cell Cardiol 2021 Mar 27;156:79-81. Epub 2021 Mar 27.

Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, Faculty Biology, Medicine and Health, University of Manchester, AV Hill Building, Oxford Road, Manchester M13 9PT, UK. Electronic address:

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http://dx.doi.org/10.1016/j.yjmcc.2021.03.011DOI Listing
March 2021

PMCA4 inhibition does not affect cardiac remodelling following myocardial infarction, but may reduce susceptibility to arrhythmia.

Sci Rep 2021 Jan 15;11(1):1518. Epub 2021 Jan 15.

Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK.

Ischaemic heart disease is the world's leading cause of mortality. Survival rates from acute myocardial infarction (MI) have improved in recent years; however, this has led to an increase in the prevalence of heart failure (HF) due to chronic remodelling of the infarcted myocardium, for which treatment options remain poor. We have previously shown that inhibition of isoform 4 of the plasma membrane calcium ATPase (PMCA4) prevents chronic remodelling and HF development during pressure overload, through fibroblast mediated Wnt signalling modulation. Given that Wnt signalling also plays a prominent role during remodelling of the infarcted heart, this study investigated the effect of genetic and functional loss of PMCA4 on cardiac outcomes following MI. Neither genetic deletion nor pharmacological inhibition of PMCA4 affected chronic remodelling of the post-MI myocardium. This was the case when PMCA4 was deleted globally, or specifically from cardiomyocytes or fibroblasts. PMCA4-ablated hearts were however less prone to acute arrhythmic events, which may offer a slight survival benefit. Overall, this study demonstrates that PMCA4 inhibition does not affect chronic outcomes following MI.
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http://dx.doi.org/10.1038/s41598-021-81170-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7810749PMC
January 2021

A circadian clock in the sinus node mediates day-night rhythms in Hcn4 and heart rate.

Heart Rhythm 2020 Dec 3. Epub 2020 Dec 3.

Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom; Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.

Background: Heart rate follows a diurnal variation, and slow heart rhythms occur primarily at night.

Objective: The lower heart rate during sleep is assumed to be neural in origin, but here we tested whether a day-night difference in intrinsic pacemaking is involved.

Methods: In vivo and in vitro electrocardiographic recordings, vagotomy, transgenics, quantitative polymerase chain reaction, Western blotting, immunohistochemistry, patch clamp, reporter bioluminescence recordings, and chromatin immunoprecipitation were used.

Results: The day-night difference in the average heart rate of mice was independent of fluctuations in average locomotor activity and persisted under pharmacological, surgical, and transgenic interruption of autonomic input to the heart. Spontaneous beating rate of isolated (ie, denervated) sinus node (SN) preparations exhibited a day-night rhythm concomitant with rhythmic messenger RNA expression of ion channels including hyperpolarization activated cyclic nucleotide gated potassium channel 4 (HCN4). In vitro studies demonstrated 24-hour rhythms in the human HCN4 promoter and the corresponding funny current. The day-night heart rate difference in mice was abolished by HCN block, both in vivo and in the isolated SN. Rhythmic expression of canonical circadian clock transcription factors, for example, Brain and muscle ARNT-Like 1 (BMAL1) and Cryptochrome (CRY) was identified in the SN and disruption of the local clock (by cardiac-specific knockout of Bmal1) abolished the day-night difference in Hcn4 and intrinsic heart rate. Chromatin immunoprecipitation revealed specific BMAL1 binding sites on Hcn4, linking the local clock with intrinsic rate control.

Conclusion: The circadian variation in heart rate involves SN local clock-dependent Hcn4 rhythmicity. Data reveal a novel regulator of heart rate and mechanistic insight into bradycardia during sleep.
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http://dx.doi.org/10.1016/j.hrthm.2020.11.026DOI Listing
December 2020

Signaling via the Interleukin-10 Receptor Attenuates Cardiac Hypertrophy in Mice During Pressure Overload, but not Isoproterenol Infusion.

Front Pharmacol 2020 30;11:559220. Epub 2020 Oct 30.

Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom.

Inflammation plays a key role during cardiac hypertrophy and the development of heart failure. Interleukin-10 (IL-10) is a major anti-inflammatory cytokine that is expressed in the heart and may play a crucial role in cardiac remodeling. Based on the evidence that IL-10 potentially reduces pathological hypertrophy, it was hypothesized that signaling via the IL-10 receptor (IL10R) in the heart produces a protective role in reducing cardiac hypertrophy. The aim of this study was to investigate the effects of the ablation of gene during pathological cardiac hypertrophy in mice. We found that IL-10R1 gene silencing in cultured cardiomyocytes diminished the anti-hypertrophic effect of Il-10 in TNF-α induced hypertrophy model. We then analyzed mice deficient in the gene (IL-10R1 mice) and subjected them to transverse aortic constriction or isoproterenol infusion to induce pathological hypertrophy. In response to transverse aortic constriction for 2 weeks, IL-10R1 mice displayed a significant increase in the hypertrophic response as indicated by heart weight/body weight ratio, which was accompanied by significant increases in cardiomyocyte surface area and interstitial fibrosis. In contrast, there was no difference in hypertrophic response to isoproterenol infusion (10 days) between the knockout and control groups. Analysis of cardiac function using echocardiography and invasive hemodynamic studies did not show any difference between the WT and IL-10R1 groups, most likely due to the short term nature of the models. In conclusion, our data shows that signaling via the IL-10 receptor may produce protective effects against pressure overload-induced hypertrophy but not against β-adrenergic stimuli in the heart. Our data supports previous evidence that signaling modulated by IL-10 and its receptor may become a potential target to control pathological cardiac hypertrophy.
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http://dx.doi.org/10.3389/fphar.2020.559220DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7662881PMC
October 2020

Targeting Ca Handling Proteins for the Treatment of Heart Failure and Arrhythmias.

Front Physiol 2020 4;11:1068. Epub 2020 Sep 4.

Division of Cardiovascular Sciences, The University of Manchester, Manchester, United Kingdom.

Diseases of the heart, such as heart failure and cardiac arrhythmias, are a growing socio-economic burden. Calcium (Ca) dysregulation is key hallmark of the failing myocardium and has long been touted as a potential therapeutic target in the treatment of a variety of cardiovascular diseases (CVD). In the heart, Ca is essential for maintaining normal cardiac function through the generation of the cardiac action potential and its involvement in excitation contraction coupling. As such, the proteins which regulate Ca cycling and signaling play a vital role in maintaining Ca homeostasis. Changes to the expression levels and function of Ca-channels, pumps and associated intracellular handling proteins contribute to altered Ca homeostasis in CVD. The remodeling of Ca-handling proteins therefore results in impaired Ca cycling, Ca leak from the sarcoplasmic reticulum and reduced Ca clearance, all of which contributes to increased intracellular Ca. Currently, approved treatments for targeting Ca handling dysfunction in CVD are focused on Ca channel blockers. However, whilst Ca channel blockers have been successful in the treatment of some arrhythmic disorders, they are not universally prescribed to heart failure patients owing to their ability to depress cardiac function. Despite the progress in CVD treatments, there remains a clear need for novel therapeutic approaches which are able to reverse pathophysiology associated with heart failure and arrhythmias. Given that heart failure and cardiac arrhythmias are closely associated with altered Ca homeostasis, this review will address the molecular changes to proteins associated with both Ca-handling and -signaling; their potential as novel therapeutic targets will be discussed in the context of pre-clinical and, where available, clinical data.
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http://dx.doi.org/10.3389/fphys.2020.01068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7498719PMC
September 2020

Cardiac hypertrophy or failure? - A systematic evaluation of the transverse aortic constriction model in C57BL/6NTac and C57BL/6J substrains.

Curr Res Physiol 2019 Dec;1:1-10

Division of Cardiovascular Sciences, University of Manchester and Manchester Academic Health Science Centre, Manchester, United Kingdom.

Background: The mouse model of transverse aortic constriction (TAC) has been widely used as a cardiac stress in the investigation of the molecular mechanisms of cardiac hypertrophy. Recently, the International Knockout Mouse Consortium has selected the C57BL/6NTac (BL/6N) mouse strain to generate null alleles for all mouse genes; however, a range of genetic and cardiac phenotypic differences have been reported between this substrain and the commonly used C57BL/6J (BL/6J) substrain. It has been reported by Garcia-Menendez and colleagues that 12-week C57BL/6NTac mice are susceptible to heart failure but little is known about the cardiac remodeling in this substrain as cardiac function progresses from compensation to decompensation.

Methods: BL/6J and BL/6N mice were subjected to pressure overload via TAC. The impact of both age and duration of cardiac pressure overload induced by TAC on cardiac remodelling were systematically assessed.

Results: Our data showed that BL/6N mice developed eccentric hypertrophy with age- and time-dependent deterioration in cardiac function, accompanied by considerable interstitial fibrosis. In contrast, BL/6J mice were more resilient to TAC-induced cardiac stress and developed variable cardiac phenotypes independent of age and the duration of pressure overload. This was likely due to the greater variability in pre-TAC aortic arch dimension as measured by echocardiography. In addition to increased expression of brain natriuretic peptide and collagen gene type 1 and 3, BL/6N mice also had greater angiotensin II type 2 receptor (AT2R) gene expression than BL/6J counterparts at baseline and after 2-weeks TAC, which may contribute to the exacerbated interstitial fibrosis.

Conclusions: BL/6N and BL/6J mice have very different responses to TAC stimulation and these differences should be taken into consideration when using the substrains to investigate the mechanisms of hypertrophy and heart failure.
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http://dx.doi.org/10.1016/j.crphys.2019.10.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7357793PMC
December 2019

Silencing miR-370-3p rescues funny current and sinus node function in heart failure.

Sci Rep 2020 07 9;10(1):11279. Epub 2020 Jul 9.

Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 2200N, Copenhagen, Denmark.

Bradyarrhythmias are an important cause of mortality in heart failure and previous studies indicate a mechanistic role for electrical remodelling of the key pacemaking ion channel HCN4 in this process. Here we show that, in a mouse model of heart failure in which there is sinus bradycardia, there is upregulation of a microRNA (miR-370-3p), downregulation of the pacemaker ion channel, HCN4, and downregulation of the corresponding ionic current, I, in the sinus node. In vitro, exogenous miR-370-3p inhibits HCN4 mRNA and causes downregulation of HCN4 protein, downregulation of I, and bradycardia in the isolated sinus node. In vivo, intraperitoneal injection of an antimiR to miR-370-3p into heart failure mice silences miR-370-3p and restores HCN4 mRNA and protein and I in the sinus node and blunts the sinus bradycardia. In addition, it partially restores ventricular function and reduces mortality. This represents a novel approach to heart failure treatment.
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http://dx.doi.org/10.1038/s41598-020-67790-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7347645PMC
July 2020

Substrate for the Myocardial Inflammation-Heart Failure Hypothesis Identified Using Novel USPIO Methodology.

JACC Cardiovasc Imaging 2021 Feb 15;14(2):365-376. Epub 2020 Apr 15.

Manchester University NHS Foundation Trust, Wythenshawe Hospital, Manchester, United Kingdom; Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom; Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester, United Kingdom. Electronic address:

Objectives: The purpose of this study was to identify where ultrasmall superparamagnetic particles of iron oxide (USPIO) locate to in myocardium, develop a methodology that differentiates active macrophage uptake of USPIO from passive tissue distribution; and investigate myocardial inflammation in cardiovascular diseases.

Background: Myocardial inflammation is hypothesized to be a key pathophysiological mechanism of heart failure (HF), but human evidence is limited, partly because evaluation is challenging. USPIO-magnetic resonance imaging (MRI) potentially allows specific identification of myocardial inflammation but it remains unclear what the USPIO-MRI signal represents.

Methods: Histological validation was performed using a murine acute myocardial infarction (MI) model. A multiparametric, multi-time-point MRI methodology was developed, which was applied in patients with acute MI (n = 12), chronic ischemic cardiomyopathy (n = 7), myocarditis (n = 6), dilated cardiomyopathy (n = 5), and chronic sarcoidosis (n = 5).

Results: USPIO were identified in myocardial macrophages and myocardial interstitium. R1 time-course reflected passive interstitial distribution whereas multi-time-point R2* was also sensitive to active macrophage uptake. R2*/R1 ratio provided a quantitative measurement of myocardial macrophage infiltration. R2* behavior and R2*/R1 ratio were higher in infarcted (p = 0.001) and remote (p = 0.033) myocardium in acute MI and in chronic ischemic cardiomyopathy (infarct: p = 0.008; remote p = 0.010), and were borderline higher in DCM (p = 0.096), in comparison to healthy controls, but were no different in myocarditis or sarcoidosis. An R2*/R1 threshold of 25 had a sensitivity and specificity of 90% and 83%, respectively, for detecting active USPIO uptake.

Conclusions: USPIO are phagocytized by cardiac macrophages but are also passively present in myocardial interstitium. A multiparametric multi-time-point MRI methodology specifically identifies active myocardial macrophage infiltration. Persistent active macrophage infiltration is present in infarcted and remote myocardium in chronic ischemic cardiomyopathy, providing a substrate for HF.
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http://dx.doi.org/10.1016/j.jcmg.2020.02.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7854561PMC
February 2021

Targeting alleviates myocardial insulin resistance and prevents ischemia-induced heart failure.

Elife 2020 03 30;9. Epub 2020 Mar 30.

Faculty of Biology, Medicine, and Health, the University of Manchester, Manchester, United Kingdom.

Myocardial insulin resistance contributes to heart failure in response to pathological stresses, therefore, a therapeutic strategy to maintain cardiac insulin pathways requires further investigation. We demonstrated that insulin receptor substrate 1 (IRS1) was reduced in failing mouse hearts post-myocardial infarction (MI) and failing human hearts. The mice manifesting severe cardiac dysfunction post-MI displayed elevated in the myocardium. Ischemia-upregulated promoted degradation. Using rat cardiomyocytes and human-induced pluripotent stem cell-derived cardiomyocytes, we elucidated that mitogen-activated protein kinase 7 (MAPK7, also known as ERK5)-mediated CCAAT/enhancer-binding protein beta (CEBPβ) transcriptionally represses under hypoxia. Therapeutically, functional studies demonstrated gene therapy-delivered cardiac-specific MAPK7 restoration or overexpression of CEBPβ impeded cardiac injury after MI, at least partly due to normalization of . Furthermore, inhibition of preserved and ameliorated cardiac dysfunction post-MI. In conclusion, we reveal that targeting mitigates myocardial insulin resistance, thereafter slowing down the progression of heart failure post-ischemia.
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http://dx.doi.org/10.7554/eLife.54298DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7124275PMC
March 2020

Cardiac mitochondrial function depends on BUD23 mediated ribosome programming.

Elife 2020 01 15;9. Epub 2020 Jan 15.

Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom.

Efficient mitochondrial function is required in tissues with high energy demand such as the heart, and mitochondrial dysfunction is associated with cardiovascular disease. Expression of mitochondrial proteins is tightly regulated in response to internal and external stimuli. Here we identify a novel mechanism regulating mitochondrial content and function, through BUD23-dependent ribosome generation. BUD23 was required for ribosome maturation, normal 18S/28S stoichiometry and modulated the translation of mitochondrial transcripts in human A549 cells. Deletion of in murine cardiomyocytes reduced mitochondrial content and function, leading to severe cardiomyopathy and death. We discovered that BUD23 selectively promotes ribosomal interaction with low GC-content 5'UTRs. Taken together we identify a critical role for BUD23 in bioenergetics gene expression, by promoting efficient translation of mRNA transcripts with low 5'UTR GC content. BUD23 emerges as essential to mouse development, and to postnatal cardiac function.
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http://dx.doi.org/10.7554/eLife.50705DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7002040PMC
January 2020

Cardiomyocyte damage control in heart failure and the role of the sarcolemma.

J Muscle Res Cell Motil 2019 12 13;40(3-4):319-333. Epub 2019 Sep 13.

Division of Cardiovascular Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, AV Hill, Dover Street, Manchester, M13 9PL, UK.

The cardiomyocyte plasma membrane, termed the sarcolemma, is fundamental for regulating a myriad of cellular processes. For example, the structural integrity of the cardiomyocyte sarcolemma is essential for mediating cardiac contraction by forming microdomains such as the t-tubular network, caveolae and the intercalated disc. Significantly, remodelling of these sarcolemma microdomains is a key feature in the development and progression of heart failure (HF). However, despite extensive characterisation of the associated molecular and ultrastructural events there is a lack of clarity surrounding the mechanisms driving adverse morphological rearrangements. The sarcolemma also provides protection, and is the cell's first line of defence, against external stresses such as oxygen and nutrient deprivation, inflammation and oxidative stress with a loss of sarcolemma viability shown to be a key step in cell death via necrosis. Significantly, cumulative cell death is also a feature of HF, and is linked to disease progression and loss of cardiac function. Herein, we will review the link between structural and molecular remodelling of the sarcolemma associated with the progression of HF, specifically considering the evidence for: (i) Whether intrinsic, evolutionary conserved, plasma membrane injury-repair mechanisms are in operation in the heart, and (ii) if deficits in key 'wound-healing' proteins (annexins, dysferlin, EHD2 and MG53) may play a yet to be fully appreciated role in triggering sarcolemma microdomain remodelling and/or necrosis. Cardiomyocytes are terminally differentiated with very limited regenerative capability and therefore preserving cell viability and cardiac function is crucially important. This review presents a novel perspective on sarcolemma remodelling by considering whether targeting proteins that regulate sarcolemma injury-repair may hold promise for developing new strategies to attenuate HF progression.
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http://dx.doi.org/10.1007/s10974-019-09539-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6831538PMC
December 2019

Pharmacological inhibition of Hippo pathway, with the novel kinase inhibitor XMU-MP-1, protects the heart against adverse effects during pressure overload.

Br J Pharmacol 2019 10 8;176(20):3956-3971. Epub 2019 Oct 8.

Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.

Background And Purpose: The Hippo pathway has emerged as a potential therapeutic target to control pathological cardiac remodelling. The core components of the Hippo pathway, mammalian Ste-20 like kinase 1 (Mst1) and mammalian Ste-20 like kinase 2 (Mst2), modulate cardiac hypertrophy, apoptosis, and fibrosis. Here, we study the effects of pharmacological inhibition of Mst1/2 using a novel inhibitor XMU-MP-1 in controlling the adverse effects of pressure overload-induced hypertrophy.

Experimental Approach: We used cultured neonatal rat cardiomyocytes (NRCM) and C57Bl/6 mice with transverse aortic constriction (TAC) as in vitro and in vivo models, respectively, to test the effects of XMU-MP-1 treatment. We used luciferase reporter assays, western blots and immunofluorescence assays in vitro, with echocardiography, qRT-PCR and immunohistochemical methods in vivo.

Key Results: XMU-MP-1 treatment significantly increased activity of the Hippo pathway effector yes-associated protein and inhibited phenylephrine-induced hypertrophy in NRCM. XMU-MP-1 improved cardiomyocyte survival and reduced apoptosis following oxidative stress. In vivo, mice 3 weeks after TAC, were treated with XMU-MP-1 (1 mg·kg ) every alternate day for 10 further days. XMU-MP-1-treated mice showed better cardiac contractility than vehicle-treated mice. Cardiomyocyte cross-sectional size and expression of the hypertrophic marker, brain natriuretic peptide, were reduced in XMU-MP-1-treated mice. Improved heart function in XMU-MP-1-treated mice with TAC, was accompanied by fewer TUNEL positive cardiomyocytes and lower levels of fibrosis, suggesting inhibition of cardiomyocyte apoptosis and decreased fibrosis.

Conclusions And Implications: The Hippo pathway inhibitor, XMU-MP-1, reduced cellular hypertrophy and improved survival in cultured cardiomyocytes and, in vivo, preserved cardiac function following pressure overload.
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http://dx.doi.org/10.1111/bph.14795DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6811740PMC
October 2019

TNAP limits TGF-β-dependent cardiac and skeletal muscle fibrosis by inactivating the SMAD2/3 transcription factors.

J Cell Sci 2019 08 8;132(15). Epub 2019 Aug 8.

Division of Cell Matrix Biology & Regenerative Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK

Fibrosis is associated with almost all forms of chronic cardiac and skeletal muscle diseases. The accumulation of extracellular matrix impairs the contractility of muscle cells contributing to organ failure. Transforming growth factor β (TGF-β) plays a pivotal role in fibrosis, activating pro-fibrotic gene programmes via phosphorylation of SMAD2/3 transcription factors. However, the mechanisms that control de-phosphorylation of SMAD2 and SMAD3 (SMAD2/3) have remained poorly characterized. Here, we show that tissue non-specific alkaline phosphatase (TNAP, also known as ALPL) is highly upregulated in hypertrophic hearts and in dystrophic skeletal muscles, and that the abrogation of TGF-β signalling in TNAP-positive cells reduces vascular and interstitial fibrosis. We show that TNAP colocalizes and interacts with SMAD2. The TNAP inhibitor MLS-0038949 increases SMAD2/3 phosphorylation, while TNAP overexpression reduces SMAD2/3 phosphorylation and the expression of downstream fibrotic genes. Overall our data demonstrate that TNAP negatively regulates TGF-β signalling and likely represents a mechanism to limit fibrosis.
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http://dx.doi.org/10.1242/jcs.234948DOI Listing
August 2019

Pak2 as a Novel Therapeutic Target for Cardioprotective Endoplasmic Reticulum Stress Response.

Circ Res 2019 03;124(5):696-711

From the Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom (P.B., S.W., M.Z., L.C., S.K., Y.L., N.H., E.S., A.R., D.O., E.J.C., X.W., W.L.).

Rationale: Secreted and membrane-bound proteins, which account for 1/3 of all proteins, play critical roles in heart health and disease. The endoplasmic reticulum (ER) is the site for synthesis, folding, and quality control of these proteins. Loss of ER homeostasis and function underlies the pathogenesis of many forms of heart disease.

Objective: To investigate mechanisms responsible for regulating cardiac ER function, and to explore therapeutic potentials of strengthening ER function to treat heart disease.

Methods And Results: Screening a range of signaling molecules led to the discovery that Pak (p21-activated kinase)2 is a stress-responsive kinase localized in close proximity to the ER membrane in cardiomyocytes. We found that Pak2 cardiac deleted mice (Pak2-CKO) under tunicamycin stress or pressure overload manifested a defective ER response, cardiac dysfunction, and profound cell death. Small chemical chaperone tauroursodeoxycholic acid treatment of Pak2-CKO mice substantiated that Pak2 loss-induced cardiac damage is an ER-dependent pathology. Gene array analysis prompted a detailed mechanistic study, which revealed that Pak2 regulation of protective ER function was via the IRE (inositol-requiring enzyme)-1/XBP (X-box-binding protein)-1-dependent pathway. We further discovered that this regulation was conferred by Pak2 inhibition of PP2A (protein phosphatase 2A) activity. Moreover, IRE-1 activator, Quercetin, and adeno-associated virus serotype-9-delivered XBP-1s were able to relieve ER dysfunction in Pak2-CKO hearts. This provides functional evidence, which supports the mechanism underlying Pak2 regulation of IRE-1/XBP-1s signaling. Therapeutically, inducing Pak2 activation by genetic overexpression or adeno-associated virus serotype-9-based gene delivery was capable of strengthening ER function, improving cardiac performance, and diminishing apoptosis, thus protecting the heart from failure.

Conclusions: Our findings uncover a new cardioprotective mechanism, which promotes a protective ER stress response via the modulation of Pak2. This novel therapeutic strategy may present as a promising option for treating cardiac disease and heart failure.
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http://dx.doi.org/10.1161/CIRCRESAHA.118.312829DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6407830PMC
March 2019

Acute inhibition of PMCA4, but not global ablation, reduces blood pressure and arterial contractility via a nNOS-dependent mechanism.

J Cell Mol Med 2018 02 30;22(2):861-872. Epub 2017 Nov 30.

Faculty of Biology, Medicine and Health, Division of Cardiovascular Sciences, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.

Cardiovascular disease is the world's leading cause of morbidity and mortality, with high blood pressure (BP) contributing to increased severity and number of adverse outcomes. Plasma membrane calcium ATPase 4 (PMCA4) has been previously shown to modulate systemic BP. However, published data are conflicting, with both overexpression and inhibition of PMCA4 in vivo shown to increase arterial contractility. Hence, our objective was to determine the role of PMCA4 in the regulation of BP and to further understand how PMCA4 functionally regulates BP using a novel specific inhibitor to PMCA4, aurintricarboxylic acid (ATA). Our approach assessed conscious BP and contractility of resistance arteries from PMCA4 global knockout (PMCA4KO) mice compared to wild-type animals. Global ablation of PMCA4 had no significant effect on BP, arterial structure or isolated arterial contractility. ATA treatment significantly reduced BP and arterial contractility in wild-type mice but had no significant effect in PMCA4KO mice. The effect of ATAin vivo and ex vivo was abolished by the neuronal nitric oxide synthase (nNOS) inhibitor Vinyl-l-NIO. Thus, this highlights differences in the effects of PMCA4 ablation and acute inhibition on the vasculature. Importantly, for doses here used, we show the vascular effects of ATA to be specific for PMCA4 and that ATA may be a further experimental tool for elucidating the role of PMCA4.
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http://dx.doi.org/10.1111/jcmm.13371DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5783868PMC
February 2018

Advanced glycation end products reduce the calcium transient in cardiomyocytes by increasing production of reactive oxygen species and nitric oxide.

FEBS Open Bio 2017 11 26;7(11):1672-1685. Epub 2017 Sep 26.

Division of Cardiovascular Sciences The University of Manchester, Manchester Academic Health Science Centre UK.

Advanced glycation end products (AGE) are central to the development of cardiovascular complications associated with diabetes mellitus. AGE may alter cellular function through cross-linking of cellular proteins or by activating the AGE receptor (RAGE). However, the signalling molecules involved during AGE stimulation in cardiomyocytes remain unclear. Here, we investigated the effects of AGE treatment on intracellular calcium homeostasis of isolated cardiomyocytes and studied the activation of signalling molecules involved in this process. Treatment of cardiomyocytes with AGE for 24 h resulted in a dose-dependent reduction in calcium transient amplitude, reaching a maximum 50% reduction at a dose of 1 mg·mL. This was accompanied with a 32% reduction in sarcoplasmic reticulum calcium content but without any detectable changes in the expression of major calcium channels. Mechanistically, we observed a significant increase in the production of reactive oxygen species (ROS) in AGE-treated cardiomyocytes and enhancement of NADPH oxidase activity. This was accompanied with activation of p38 kinase and nuclear translocation of NF-κB, and subsequently induction of inducible NO synthase (iNOS) expression, leading to excessive nitric oxide production. Overall, our data reveal the molecular signalling that may underlie the alteration of intracellular calcium homeostasis in cardiac myocytes due to AGE stimulation. This may provide new insights into the pathophysiological mechanisms of the development of diabetic cardiomyopathy.
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http://dx.doi.org/10.1002/2211-5463.12284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5666397PMC
November 2017

Plasma membrane Ca -ATPase 1 is required for maintaining atrial Ca homeostasis and electrophysiological stability in the mouse.

J Physiol 2017 12 9;595(24):7383-7398. Epub 2017 Nov 9.

Department of Pharmacology, University of Oxford, Oxford, UK.

Key Points: The role of plasma membrane Ca -ATPase 1 (PMCA1) in Ca homeostasis and electrical stability in atrial tissue has been investigated at both organ and cellular levels in mice with cardiomyocyte-specific deletion of PMCA1 (PMCA1 ) The PMCA1 hearts became more susceptible to atrial arrhythmic stress conditions than PMCA1 hearts. PMCA1 deficiency alters cellular Ca homeostasis under both baseline and stress conditions. PMCA1 is required for maintaining cellular Ca homeostasis and electrical stability in murine atria under stress conditions.

Abstract: To determine the role of plasma membrane Ca -ATPase 1 (PMCA1) in maintaining Ca homeostasis and electrical stability in the atrium under physiological and stress conditions, mice with a cardiomyocyte-specific deletion of PMCA1 (PMCA1 ) and their control littermates (PMCA1 ) were studied at the organ and cellular levels. At the organ level, the PMCA1 hearts became more susceptible to atrial arrhythmias under rapid programmed electrical stimulation compared with the PMCA1 hearts, and such arrhythmic events became more severe under Ca overload conditions. At the cellular level, the occurrence of irregular-type action potentials of PMCA1 atrial myocytes increased significantly under Ca overload conditions and/or at higher frequency of stimulation. The decay of Na /Ca exchanger current that followed a stimulation protocol was significantly prolonged in PMCA1 atrial myocytes under basal conditions, with Ca overload leading to even greater prolongation. In conclusion, PMCA1 is required for maintaining Ca homeostasis and electrical stability in the atrium. This is particularly critical during fast removal of Ca from the cytosol, which is required under stress conditions.
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http://dx.doi.org/10.1113/JP274110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5730856PMC
December 2017

Metabolic stress-induced cardiomyopathy is caused by mitochondrial dysfunction due to attenuated Erk5 signaling.

Nat Commun 2017 09 8;8(1):494. Epub 2017 Sep 8.

Faculty of Biology, Medicine and Health, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK.

The prevalence of cardiomyopathy from metabolic stress has increased dramatically; however, its molecular mechanisms remain elusive. Here, we show that extracellular signal-regulated protein kinase 5 (Erk5) is lost in the hearts of obese/diabetic animal models and that cardiac-specific deletion of Erk5 in mice (Erk5-CKO) leads to dampened cardiac contractility and mitochondrial abnormalities with repressed fuel oxidation and oxidative damage upon high fat diet (HFD). Erk5 regulation of peroxisome proliferator-activated receptor γ co-activator-1α (Pgc-1α) is critical for cardiac mitochondrial functions. More specifically, we show that Gp91phox activation of calpain-1 degrades Erk5 in free fatty acid (FFA)-stressed cardiomyocytes, whereas the prevention of Erk5 loss by blocking Gp91phox or calpain-1 rescues mitochondrial functions. Similarly, adeno-associated virus 9 (AAV9)-mediated restoration of Erk5 expression in Erk5-CKO hearts prevents cardiomyopathy. These findings suggest that maintaining Erk5 integrity has therapeutic potential for treating metabolic stress-induced cardiomyopathy.The mechanistic link between metabolic stress and associated cardiomyopathy is unknown. Here the authors show that high fat diet causes calpain-1-dependent degradation of ERK5 leading to mitochondrial dysfunction, suggesting the maintenance of cardiac ERK5 as a therapeutic approach for cardiomyopathy prevention and/or treatment.
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http://dx.doi.org/10.1038/s41467-017-00664-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5591279PMC
September 2017

Targeting miR-423-5p Reverses Exercise Training-Induced HCN4 Channel Remodeling and Sinus Bradycardia.

Circ Res 2017 Oct 17;121(9):1058-1068. Epub 2017 Aug 17.

From the Division of Cardiovascular Sciences, University of Manchester, United Kingdom (A.D., C.M.P., Y.W., S.N., S.J.R.J.L., C.C., H.B., Y.Z., J.E., A.R., A.K., E.J.C., O.M., H.D., D.O., G.M.M., M.R.B.); K.G. Jebsen Center for Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway (A.B.J., U.W.); Faculty of Health Sciences, NNF Center for Protein Research, University of Copenhagen, Denmark (N.L., P.C.P., A.L.); School of Healthcare Science, Manchester Metropolitan University, United Kingdom (J.C., J.M.); Department of Cardiology, CARIM School for Cardiovascular Diseases, Faculty of Health, Medicine and Life Sciences, Maastricht University, Netherlands (P.A.d.C.M.); and School of Human Movement & Nutrition Sciences, University of Queensland, Australia (U.W.).

Rationale: Downregulation of the pacemaking ion channel, HCN4 (hyperpolarization-activated cyclic nucleotide gated channel 4), and the corresponding ionic current, , underlies exercise training-induced sinus bradycardia in rodents. If this occurs in humans, it could explain the increased incidence of bradyarrhythmias in veteran athletes, and it will be important to understand the underlying processes.

Objective: To test the role of HCN4 in the training-induced bradycardia in human athletes and investigate the role of microRNAs (miRs) in the repression of HCN4.

Methods And Results: As in rodents, the intrinsic heart rate was significantly lower in human athletes than in nonathletes, and in all subjects, the rate-lowering effect of the HCN selective blocker, ivabradine, was significantly correlated with the intrinsic heart rate, consistent with HCN repression in athletes. Next-generation sequencing and quantitative real-time reverse transcription polymerase chain reaction showed remodeling of miRs in the sinus node of swim-trained mice. Computational predictions highlighted a prominent role for miR-423-5p. Interaction between miR-423-5p and HCN4 was confirmed by a dose-dependent reduction in HCN4 3'-untranslated region luciferase reporter activity on cotransfection with precursor miR-423-5p (abolished by mutation of predicted recognition elements). Knockdown of miR-423-5p with anti-miR-423-5p reversed training-induced bradycardia via rescue of HCN4 and . Further experiments showed that in the sinus node of swim-trained mice, upregulation of miR-423-5p (intronic miR) and its host gene, NSRP1, is driven by an upregulation of the transcription factor Nkx2.5.

Conclusions: HCN remodeling likely occurs in human athletes, as well as in rodent models. miR-423-5p contributes to training-induced bradycardia by targeting HCN4. This work presents the first evidence of miR control of HCN4 and heart rate. miR-423-5p could be a therapeutic target for pathological sinus node dysfunction in veteran athletes.
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http://dx.doi.org/10.1161/CIRCRESAHA.117.311607DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5636198PMC
October 2017

Reduced expression of PMCA1 is associated with increased blood pressure with age which is preceded by remodelling of resistance arteries.

Aging Cell 2017 10 9;16(5):1104-1113. Epub 2017 Aug 9.

Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, The University of Manchester, AV Hill Building, Manchester, M13 9PT, UK.

Hypertension is a well-established risk factor for adverse cardiovascular events, and older age is a risk factor for the development of hypertension. Genomewide association studies have linked ATP2B1, the gene for the plasma membrane calcium ATPase 1 (PMCA1), to blood pressure (BP) and hypertension. Here, we present the effects of reduction in the expression of PMCA1 on BP and small artery structure and function when combined with advancing age. Heterozygous PMCA1 null mice (PMCA1 ) were generated and conscious BP was measured at 6 to 18 months of age. Passive and active properties of isolated small mesenteric arteries were examined by pressure myography. PMCA1 mice exhibited normal BP at 6 and 9 months of age but developed significantly elevated BP when compared to age-matched wild-type controls at ≥12 months of age. Decreased lumen diameter, increased wall thickness and increased wall:lumen ratio were observed in small mesenteric arteries from animals 9 months of age and older, indicative of eutrophic remodelling. Increases in mesenteric artery intrinsic tone and global intracellular calcium were evident in animals at both 6 and 18 months of age. Thus, decreased expression of PMCA1 is associated with increased BP when combined with advancing age. Changes in arterial structure precede the elevation of BP. Pathways involving PMCA1 may be a novel target for BP regulation in the elderly.
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http://dx.doi.org/10.1111/acel.12637DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5595685PMC
October 2017

Paracrine cyclooxygenase-2 activity by macrophages drives colorectal adenoma progression in the Apc mouse model of intestinal tumorigenesis.

Sci Rep 2017 07 20;7(1):6074. Epub 2017 Jul 20.

Section of Molecular Gastroenterology, Leeds Institute of Biomedical & Clinical Sciences, University of Leeds, St James's University Hospital, Leeds, LS9 7TF, United Kingdom.

Genetic deletion or pharmacological inhibition of cyclooxygenase (COX)-2 abrogates intestinal adenoma development at early stages of colorectal carcinogenesis. COX-2 is localised to stromal cells (predominantly macrophages) in human and mouse intestinal adenomas. Therefore, we tested the hypothesis that paracrine Cox-2-mediated signalling from macrophages drives adenoma growth and progression in vivo in the Apc mouse model of intestinal tumorigenesis. Using a transgenic C57Bl/6 mouse model of Cox-2 over-expression driven by the chicken lysozyme locus (cLys-Cox-2), which directs integration site-independent, copy number-dependent transgene expression restricted to macrophages, we demonstrated that stromal macrophage Cox-2 in colorectal (but not small intestinal) adenomas from cLys-Cox-2 x Apc mice was associated with significantly increased tumour size (P = 0.025) and multiplicity (P = 0.025), compared with control Apc mice. Transgenic macrophage Cox-2 expression was associated with increased dysplasia, epithelial cell Cox-2 expression and submucosal tumour invasion, as well as increased nuclear β-catenin translocation in dysplastic epithelial cells. In vitro studies confirmed that paracrine macrophage Cox-2 signalling drives catenin-related transcription in intestinal epithelial cells. Paracrine macrophage Cox-2 activity drives growth and progression of Apc mouse colonic adenomas, linked to increased epithelial cell β-catenin dysregulation. Stromal cell (macrophage) gene regulation and signalling represent valid targets for chemoprevention of colorectal cancer.
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http://dx.doi.org/10.1038/s41598-017-06253-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5519705PMC
July 2017

Selective inhibition of plasma membrane calcium ATPase 4 improves angiogenesis and vascular reperfusion.

J Mol Cell Cardiol 2017 08 3;109:38-47. Epub 2017 Jul 3.

Cardiovascular Molecular Pharmacology Laboratory, School of Pharmacy, University of Wolverhampton, Wolverhampton, UK; CIBERCV, Spain. Electronic address:

Aims: Ischaemic cardiovascular disease is a major cause of morbidity and mortality worldwide. Despite promising results from pre-clinical animal models, VEGF-based strategies for therapeutic angiogenesis have yet to achieve successful reperfusion of ischaemic tissues in patients. Failure to restore efficient VEGF activity in the ischaemic organ remains a major problem in current pro-angiogenic therapeutic approaches. Plasma membrane calcium ATPase 4 (PMCA4) negatively regulates VEGF-activated angiogenesis via inhibition of the calcineurin/NFAT signalling pathway. PMCA4 activity is inhibited by the small molecule aurintricarboxylic acid (ATA). We hypothesize that inhibition of PMCA4 with ATA might enhance VEGF-induced angiogenesis.

Methods And Results: We show that inhibition of PMCA4 with ATA in endothelial cells triggers a marked increase in VEGF-activated calcineurin/NFAT signalling that translates into a strong increase in endothelial cell motility and blood vessel formation. ATA enhances VEGF-induced calcineurin signalling by disrupting the interaction between PMCA4 and calcineurin at the endothelial-cell membrane. ATA concentrations at the nanomolar range, that efficiently inhibit PMCA4, had no deleterious effect on endothelial-cell viability or zebrafish embryonic development. However, high ATA concentrations at the micromolar level impaired endothelial cell viability and tubular morphogenesis, and were associated with toxicity in zebrafish embryos. In mice undergoing experimentally-induced hindlimb ischaemia, ATA treatment significantly increased the reperfusion of post-ischaemic limbs.

Conclusions: Our study provides evidence for the therapeutic potential of targeting PMCA4 to improve VEGF-based pro-angiogenic interventions. This goal will require the development of refined, highly selective versions of ATA, or the identification of novel PMCA4 inhibitors.
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http://dx.doi.org/10.1016/j.yjmcc.2017.07.001DOI Listing
August 2017

The Plasma Membrane Calcium ATPases and Their Role as Major New Players in Human Disease.

Physiol Rev 2017 07;97(3):1089-1125

Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom.

The Ca extrusion function of the four mammalian isoforms of the plasma membrane calcium ATPases (PMCAs) is well established. There is also ever-increasing detail known of their roles in global and local Ca homeostasis and intracellular Ca signaling in a wide variety of cell types and tissues. It is becoming clear that the spatiotemporal patterns of expression of the PMCAs and the fact that their abundances and relative expression levels vary from cell type to cell type both reflect and impact on their specific functions in these cells. Over recent years it has become increasingly apparent that these genes have potentially significant roles in human health and disease, with PMCAs1-4 being associated with cardiovascular diseases, deafness, autism, ataxia, adenoma, and malarial resistance. This review will bring together evidence of the variety of tissue-specific functions of PMCAs and will highlight the roles these genes play in regulating normal physiological functions and the considerable impact the genes have on human disease.
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http://dx.doi.org/10.1152/physrev.00028.2016DOI Listing
July 2017

Genetic ablation of the mammalian sterile-20 like kinase 1 (Mst1) improves cell reprogramming efficiency and increases induced pluripotent stem cell proliferation and survival.

Stem Cell Res 2017 04 27;20:42-49. Epub 2017 Feb 27.

Division of Cardiovascular Sciences, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom. Electronic address:

Adult fibroblasts can be reprogrammed into induced pluripotent stem cells (iPSC) for use in various applications. However, there are challenges in iPSC generation including low reprogramming efficiency, yield, cell survival and viability. Since the Hippo signalling pathway is a key pathway involved in regulating cell proliferation and survival, we here test whether modification of the Hippo pathway will enhance the efficiency of iPSC generation and improve their survival. The Hippo pathway was modified by genetic ablation of the mammalian sterile-20 like kinase 1 (Mst1), a major component of the pathway. Using adult skin fibroblasts isolated from Mst1 knockout mice (Mst1) as a source of iPSC we found that genetic ablation of Mst1 leads to significantly increased reprogramming efficiency by 43.8%. Moreover, Mst1 iPSC displayed increase proliferation by 12% as well as an increase in cell viability by 20% when treated with a chemical hypoxic inducer. Mechanistically, we found higher activity of YAP, the main downstream effector of the Hippo pathway, in iPSC lacking Mst1. In conclusion, our data suggests that Mst1 can be targeted to improve the efficiency of adult somatic cell reprogramming as well as to enhance iPSC proliferation and survival.
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http://dx.doi.org/10.1016/j.scr.2017.02.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5376382PMC
April 2017

Stress-Activated Kinase Mitogen-Activated Kinase Kinase-7 Governs Epigenetics of Cardiac Repolarization for Arrhythmia Prevention.

Circulation 2017 02 29;135(7):683-699. Epub 2016 Nov 29.

From Faculty of Biology, Medicine and Health (S.K.C., W.L., M.Z., Y.L., S.W., H.T., S.P., C.B.M., M.R.B., E.J.C., H.A.S., X.W.) and School of Physics and Astronomy (S.C., H.Z.), University of Manchester, United Kingdom; Atherosclerosis Research Centre, Nanjing Medical University, Jiangsu, China (Y.J.); Institute of Molecular Medicine, Peking University, Beijing, China (X.Z., R.X.); Case Cardiovascular Research Institute, Case Western Reserve University, Cleveland, OH (R.Z., X.L., M.K.J.); Department of Pharmacology, University of Oxford, United Kingdom (M.L.); and Department of Cardiology and Pneumology, University Medical Center Göttingen, Germany (L.C., K.G.).

Background: Ventricular arrhythmia is a leading cause of cardiac mortality. Most antiarrhythmics present paradoxical proarrhythmic side effects, culminating in a greater risk of sudden death.

Methods: We describe a new regulatory mechanism linking mitogen-activated kinase kinase-7 deficiency with increased arrhythmia vulnerability in hypertrophied and failing hearts using mouse models harboring mitogen-activated kinase kinase-7 knockout or overexpression. The human relevance of this arrhythmogenic mechanism is evaluated in human-induced pluripotent stem cell-derived cardiomyocytes. Therapeutic potentials by targeting this mechanism are explored in the mouse models and human-induced pluripotent stem cell-derived cardiomyocytes.

Results: Mechanistically, hypertrophic stress dampens expression and phosphorylation of mitogen-activated kinase kinase-7. Such mitogen-activated kinase kinase-7 deficiency leaves histone deacetylase-2 unphosphorylated and filamin-A accumulated in the nucleus to form a complex with Krüppel-like factor-4. This complex leads to Krüppel-like factor-4 disassociation from the promoter regions of multiple key potassium channel genes (Kv4.2, KChIP2, Kv1.5, ERG1, and Kir6.2) and reduction of their transcript levels. Consequent repolarization delays result in ventricular arrhythmias. Therapeutically, targeting the repressive function of the Krüppel-like factor-4/histone deacetylase-2/filamin-A complex with the histone deacetylase-2 inhibitor valproic acid restores K channel expression and alleviates ventricular arrhythmias in pathologically remodeled hearts.

Conclusions: Our findings unveil this new gene regulatory avenue as a new antiarrhythmic target where repurposing of the antiepileptic drug valproic acid as an antiarrhythmic is supported.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.116.022941DOI Listing
February 2017

Calcium Extrusion Pump PMCA4: A New Player in Renal Calcium Handling?

PLoS One 2016 21;11(4):e0153483. Epub 2016 Apr 21.

Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.

Calcium (Ca2+) is vital for multiple processes in the body, and maintenance of the electrolyte concentration is required for everyday physiological function. In the kidney, and more specifically, in the late distal convoluted tubule and connecting tubule, the fine-tuning of Ca2+ reabsorption from the pro-urine takes place. Here, Ca2+ enters the epithelial cell via the transient receptor potential vanilloid receptor type 5 (TRPV5) channel, diffuses to the basolateral side bound to calbindin-D28k and is extruded to the blood compartment via the Na+/Ca2+ exchanger 1 (NCX1) and the plasma membrane Ca2+ ATPase (PMCA). Traditionally, PMCA1 was considered to be the primary Ca2+ pump in this process. However, in recent studies TRPV5-expressing tubules were shown to highly express PMCA4. Therefore, PMCA4 may have a predominant role in renal Ca2+ handling. This study aimed to elucidate the role of PMCA4 in Ca2+ homeostasis by characterizing the Ca2+ balance, and renal and duodenal Ca2+-related gene expression in PMCA4 knockout mice. The daily water intake of PMCA4 knockout mice was significantly lower compared to wild type littermates. There was no significant difference in serum Ca2+ level or urinary Ca2+ excretion between groups. In addition, renal and duodenal mRNA expression levels of Ca2+-related genes, including TRPV5, TRPV6, calbindin-D28k, calbindin-D9k, NCX1 and PMCA1 were similar in wild type and knockout mice. Serum FGF23 levels were significantly increased in PMCA4 knockout mice. In conclusion, PMCA4 has no discernible role in normal renal Ca2+ handling as no urinary Ca2+ wasting was observed. Further investigation of the exact role of PMCA4 in the distal convoluted tubule and connecting tubule is required.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153483PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4839660PMC
February 2017

The plasma membrane calcium ATPase 4 signalling in cardiac fibroblasts mediates cardiomyocyte hypertrophy.

Nat Commun 2016 Mar 29;7:11074. Epub 2016 Mar 29.

Institute of Cardiovascular Sciences, University of Manchester, AV Hill Building, Manchester M13 9PT, UK.

The heart responds to pathological overload through myocyte hypertrophy. Here we show that this response is regulated by cardiac fibroblasts via a paracrine mechanism involving plasma membrane calcium ATPase 4 (PMCA4). Pmca4 deletion in mice, both systemically and specifically in fibroblasts, reduces the hypertrophic response to pressure overload; however, knocking out Pmca4 specifically in cardiomyocytes does not produce this effect. Mechanistically, cardiac fibroblasts lacking PMCA4 produce higher levels of secreted frizzled related protein 2 (sFRP2), which inhibits the hypertrophic response in neighbouring cardiomyocytes. Furthermore, we show that treatment with the PMCA4 inhibitor aurintricarboxylic acid (ATA) inhibits and reverses cardiac hypertrophy induced by pressure overload in mice. Our results reveal that PMCA4 regulates the development of cardiac hypertrophy and provide proof of principle for a therapeutic approach to treat this condition.
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http://dx.doi.org/10.1038/ncomms11074DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4820544PMC
March 2016

Plasma membrane calcium ATPases (PMCAs) as potential targets for the treatment of essential hypertension.

Pharmacol Ther 2016 Mar 25;159:23-34. Epub 2016 Jan 25.

Faculty of Health and Social Care, Edge Hill University, UK. Electronic address:

The incidence of hypertension, the major modifiable risk factor for cardiovascular disease, is increasing. Thus, there is a pressing need for the development of new and more effective strategies to prevent and treat hypertension. Development of these relies on a continued evolution of our understanding of the mechanisms which control blood pressure (BP). Resistance arteries are important in the regulation of total peripheral resistance and BP; changes in their structure and function are strongly associated with hypertension. Anti-hypertensives which both reduce BP and reverse changes in resistance arterial structure reduce cardiovascular risk more than therapies which reduce BP alone. Hence, identification of novel potential vascular targets which modify BP is important. Hypertension is a multifactorial disorder which may include a genetic component. Genome wide association studies have identified ATP2B1, encoding the calcium pump plasma membrane calcium ATPase 1 (PMCA1), as having a strong association with BP and hypertension. Knockdown or reduced PMCA1 expression in mice has confirmed a physiological role for PMCA1 in BP and resistance arterial regulation. Altered expression or inhibition of PMCA4 has also been shown to modulate these parameters. The mechanisms whereby PMCA1 and 4 can modulate vascular function remain to be fully elucidated but may involve regulation of intracellular calcium homeostasis and/or comprise a structural role. However, clear physiological links between PMCA and BP, coupled with experimental studies directly linking PMCA1 and 4 to changes in BP and arterial function, suggest that they may be important targets for the development of new pharmacological modulators of BP.
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http://dx.doi.org/10.1016/j.pharmthera.2016.01.013DOI Listing
March 2016

Circulating Histone Concentrations Differentially Affect the Predominance of Left or Right Ventricular Dysfunction in Critical Illness.

Crit Care Med 2016 May;44(5):e278-88

1Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom. 2Institute of Cardiovascular Sciences, Centre for Cardiac Research, University of Manchester, Manchester, United Kingdom. 3Department of Musculoskeletal Biology II, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom. 4Intensive Care Unit, Royal Liverpool University Hospital, Liverpool, United Kingdom. 5Roald Dahl Haemostasis and Thrombosis Centre, Royal Liverpool University Hospital, Liverpool, United Kingdom.

Objectives: Cardiac complications are common in critical illness and associated with grave consequences. In this setting, elevated circulating histone levels have been linked to cardiac injury and dysfunction in experimental models and patients with sepsis. The mechanisms underlying histone-induced cardiotoxicity and the functional consequences on left ventricle and right ventricle remain unclear. This study aims to examine dose-dependent effects of circulating histones on left ventricle and right ventricle function at clinically relevant concentrations.

Design: Prospective laboratory study with in vitro and in vivo investigations.

Setting: University research laboratory.

Subjects: Twelve-week old male C57BL/6N mice.

Interventions: Cultured cardiomyocytes were incubated with clinically relevant histone concentrations, and a histone infusion mouse model was also used with hemodynamic changes characterized by echocardiography and left ventricle/right ventricle catheter-derived variables. Circulating histones and cardiac troponin levels were obtained from serial blood samples.

Measurements And Main Results: IV histone infusion caused time-dependent cardiac troponin elevation to indicate cardiac injury. At moderate sublethal histone doses (30 mg/kg), left ventricular contractile dysfunction was the prominent abnormality with reduced ejection fraction and prolonged relaxation time. At high doses (≥ 60 mg/kg), pulmonary vascular obstruction induced right ventricular pressure increase and dilatation, but left ventricular end-diastolic volume improved because of reduced blood return from the lungs. Mechanistically, histones induced profound calcium influx and overload in cultured cardiomyocytes with dose-dependent detrimental effects on intracellular calcium transient amplitude, contractility, and rhythm, suggesting that histones directly affect cardiomyocyte function adversely. However, increasing histone-induced neutrophil congestion, neutrophil extracellular trap formation, and thrombosis in the pulmonary microvasculature culminated in right ventricular dysfunction. Antihistone antibody treatment abrogated histone cardiotoxicity.

Conclusions: Circulating histones significantly compromise left ventricular and right ventricular function through different mechanisms that are dependent on histone concentrations. This provides a translational basis to explain and target the spectral manifestations of cardiac dysfunction in critical illness.
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http://dx.doi.org/10.1097/CCM.0000000000001413DOI Listing
May 2016