Publications by authors named "Elena Chepurko"

23 Publications

  • Page 1 of 1

Direct Reprogramming Induces Vascular Regeneration Post Muscle Ischemic Injury.

Mol Ther 2021 Jul 28. Epub 2021 Jul 28.

Cardiovascular Research Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA, 10029; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA, 10029; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA, 10029. Electronic address:

Reprogramming non-cardiomyocytes (non-CMs) into cardiomyocyte (CM)-like cells is a promising strategy for cardiac regeneration in conditions such as ischemic heart disease. Here, we used a modified mRNA (modRNA) gene delivery platform to deliver a cocktail of four cardiac-reprogramming genes (Gata4 (G), Mef2c (M), Tbx5 (T) and Hand2 (H)) together with three reprogramming-helper genes (Dominant Negative (DN)-TGFβ, DN-Wnt8a and Acid ceramidase (AC)), termed 7G-modRNA, to induce CM-like cells. We showed that 7G-modRNA reprogrammed 57% of CM-like cells in vitro. Through a lineage-tracing model, we determined that delivering the 7G-modRNA cocktail at the time of myocardial infarction reprogrammed ∼25% of CM-like cells in the scar area and significantly improved cardiac function, scar size, long-term survival and capillary density. Mechanistically, we determined that while 7G-modRNA cannot create de-novo beating CMs in vitro or in vivo, it can significantly upregulate pro-angiogenic mesenchymal stromal cells markers and transcription factors. We also demonstrated that our 7G-modRNA cocktail leads to neovascularization in ischemic-limb injury, indicating CM-like cells importance in other organs besides the heart. modRNA is currently being used around the globe for vaccination against COVID-19, and this study proves this is a safe, highly efficient gene delivery approach with therapeutic potential to treat ischemic diseases.
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http://dx.doi.org/10.1016/j.ymthe.2021.07.014DOI Listing
July 2021

Therapeutic Delivery of Pip4k2c-Modified mRNA Attenuates Cardiac Hypertrophy and Fibrosis in the Failing Heart.

Adv Sci (Weinh) 2021 05 12;8(10):2004661. Epub 2021 Mar 12.

Cardiovascular Research Center Icahn School of Medicine at Mount Sinai New York NY 10029 USA.

Heart failure (HF) remains a major cause of morbidity and mortality worldwide. One of the risk factors for HF is cardiac hypertrophy (CH), which is frequently accompanied by cardiac fibrosis (CF). CH and CF are controlled by master regulators mTORC1 and TGF-, respectively. Type-2-phosphatidylinositol-5-phosphate-4-kinase-gamma (Pip4k2c) is a known mTORC1 regulator. It is shown that Pip4k2c is significantly downregulated in the hearts of CH and HF patients as compared to non-injured hearts. The role of Pip4k2c in the heart during development and disease is unknown. It is shown that deleting Pip4k2c does not affect normal embryonic cardiac development; however, three weeks after TAC, adult Pip4k2c mice has higher rates of CH, CF, and sudden death than wild-type mice. In a gain-of-function study using a TAC mouse model, Pip4k2c is transiently upregulated using a modified mRNA (modRNA) gene delivery platform, which significantly improve heart function, reverse CH and CF, and lead to increased survival. Mechanistically, it is shown that Pip4k2c inhibits TGF1 via its N-terminal motif, Pip5k1, phospho-AKT 1/2/3, and phospho-Smad3. In sum, loss-and-gain-of-function studies in a TAC mouse model are used to identify Pip4k2c as a potential therapeutic target for CF, CH, and HF, for which modRNA is a highly translatable gene therapy approach.
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http://dx.doi.org/10.1002/advs.202004661DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8132051PMC
May 2021

Specific Modified mRNA Translation System.

Circulation 2020 Dec 21;142(25):2485-2488. Epub 2020 Dec 21.

Cardiovascular Research Center (A.M., A.A.K., E.C., Y.S., L.Z.), Icahn School of Medicine at Mount Sinai, New York.

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http://dx.doi.org/10.1161/CIRCULATIONAHA.120.047211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7768930PMC
December 2020

In Vitro Synthesis of Modified RNA for Cardiac Gene Therapy.

Methods Mol Biol 2021 ;2158:281-294

Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Modified mRNA (modRNA) is a promising new gene therapy approach that has safely and effectively delivered genes into different tissues, including the heart. Current efforts to use DNA-based or viral gene therapy to induce cardiac regeneration postmyocardial infarction (MI) or in heart failure (HF) have encountered key challenges, e.g., genome integration and delayed and noncontrolled expression. By contrast, modRNA is a transient, safe, non-immunogenic, and controlled gene delivery method that is not integrated into the genome. For most therapeutic applications, especially in regenerative medicine, the ability to deliver genes to the heart transiently and with control is vital for achieving therapeutic effect. Additionally, modRNA synthesis is comparatively simple and inexpensive compared to other gene delivery methods (e.g., protein), though a simple, clear in vitro transcription (IVT) protocol for synthesizing modRNA is needed for it to be more widely used. Here, we describe a simple and improved step-by-step IVT protocol to synthesize modRNA for in vitro or in vivo applications.
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http://dx.doi.org/10.1007/978-1-0716-0668-1_21DOI Listing
March 2021

Delivery of Modified mRNA in a Myocardial Infarction Mouse Model.

J Vis Exp 2020 06 11(160). Epub 2020 Jun 11.

Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai;

Myocardial infarction (MI) is a leading cause of morbidity and mortality in the Western world. In the past decade, gene therapy has become a promising treatment option for heart disease, owing to its efficiency and exceptional therapeutic effects. In an effort to repair the damaged tissue post-MI, various studies have employed DNA-based or viral gene therapy but have faced considerable hurdles due to the poor and uncontrolled expression of the delivered genes, edema, arrhythmia, and cardiac hypertrophy. Synthetic modified mRNA (modRNA) presents a novel gene therapy approach that offers high, transient, safe, nonimmunogenic, and controlled mRNA delivery to the heart tissue without any risk of genomic integration. Due to these remarkable characteristics combined with its bell-shaped pharmacokinetics in the heart, modRNA has become an attractive approach for the treatment of heart disease. However, to increase its effectiveness in vivo, a consistent and reliable delivery method needs to be followed. Hence, to maximize modRNA delivery efficiency and yield consistency in modRNA use for in vivo applications, an optimized method of preparation and delivery of modRNA intracardiac injection in a mouse MI model is presented. This protocol will make modRNA delivery more accessible for basic and translational research.
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http://dx.doi.org/10.3791/60832DOI Listing
June 2020

Probing myeloid cell dynamics in ischaemic heart disease by nanotracer hot-spot imaging.

Nat Nanotechnol 2020 05 20;15(5):398-405. Epub 2020 Apr 20.

BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Ischaemic heart disease evokes a complex immune response. However, tools to track the systemic behaviour and dynamics of leukocytes non-invasively in vivo are lacking. Here, we present a multimodal hot-spot imaging approach using an innovative high-density lipoprotein-derived nanotracer with a perfluoro-crown ether payload (F-HDL) to allow myeloid cell tracking by F magnetic resonance imaging. The F-HDL nanotracer can additionally be labelled with zirconium-89 and fluorophores to detect myeloid cells by in vivo positron emission tomography imaging and optical modalities, respectively. Using our nanotracer in atherosclerotic mice with myocardial infarction, we observed rapid myeloid cell egress from the spleen and bone marrow by in vivo F-HDL magnetic resonance imaging. Concurrently, using ex vivo techniques, we showed that circulating pro-inflammatory myeloid cells accumulated in atherosclerotic plaques and at the myocardial infarct site. Our multimodality imaging approach is a valuable addition to the immunology toolbox, enabling the study of complex myeloid cell behaviour dynamically.
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http://dx.doi.org/10.1038/s41565-020-0642-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7416336PMC
May 2020

Optimization of 5' Untranslated Region of Modified mRNA for Use in Cardiac or Hepatic Ischemic Injury.

Mol Ther Methods Clin Dev 2020 Jun 31;17:622-633. Epub 2020 Mar 31.

Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.

Modified mRNA (modRNA) is a gene-delivery platform for transiently introducing a single gene or several genes of interest to different cell types and tissues. modRNA is considered to be a safe vector for gene transfer, as it negligibly activates the innate immune system and does not compromise the genome integrity. The use of modRNA in basic and translational science is rising, due to the clinical potential of modRNA. We are currently using modRNA to induce cardiac regeneration post-ischemic injury. Major obstacles in using modRNA for cardiac ischemic disease include the need for the direct and single administration of modRNA to the heart and the inefficient translation of modRNA due to its short half-life. Modulation of the 5' untranslated region (5' UTR) to enhance translation efficiency in ischemic cardiac disease has great value, as it can reduce the amount of modRNA needed per delivery and will achieve higher and longer protein production post-single delivery. Here, we identified that 5' UTR, from the fatty acid metabolism gene carboxylesterase 1D (Ces1d), enhanced the translation of firefly luciferase (Luc) modRNA by 2-fold in the heart post-myocardial infarction (MI). Moreover, we identified, in the Ces1d, a specific RNA element (element D) that is responsible for the improvement of modRNA translation and leads to a 2.5-fold translation increment over Luc modRNA carrying artificial 5' UTR, post-MI. Importantly, we were able to show that 5' UTR Ces1d also enhances modRNA translation in the liver, but not in the kidney, post-ischemic injury, indicating that Ces1d 5' UTR and element D may play a wider role in translation of protein under an ischemic condition.
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http://dx.doi.org/10.1016/j.omtm.2020.03.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7150433PMC
June 2020

Pkm2 Regulates Cardiomyocyte Cell Cycle and Promotes Cardiac Regeneration.

Circulation 2020 04 11;141(15):1249-1265. Epub 2020 Feb 11.

Cardiovascular Research Center (A.M, N.S., A.A.K., I.M., T.M. K.B., M.T.K.S., E.C., Y.S., J.G.O., P.L, A.G.-S., C.K., M.M., L.Z.), Icahn School of Medicine at Mount Sinai, New York.

Background: The adult mammalian heart has limited regenerative capacity, mostly attributable to postnatal cardiomyocyte cell cycle arrest. In the last 2 decades, numerous studies have explored cardiomyocyte cell cycle regulatory mechanisms to enhance myocardial regeneration after myocardial infarction. Pkm2 (Pyruvate kinase muscle isoenzyme 2) is an isoenzyme of the glycolytic enzyme pyruvate kinase. The role of Pkm2 in cardiomyocyte proliferation, heart development, and cardiac regeneration is unknown.

Methods: We investigated the effect of Pkm2 in cardiomyocytes through models of loss (cardiomyocyte-specific Pkm2 deletion during cardiac development) or gain using cardiomyocyte-specific Pkm2 modified mRNA to evaluate Pkm2 function and regenerative affects after acute or chronic myocardial infarction in mice.

Results: Here, we identify Pkm2 as an important regulator of the cardiomyocyte cell cycle. We show that Pkm2 is expressed in cardiomyocytes during development and immediately after birth but not during adulthood. Loss of function studies show that cardiomyocyte-specific Pkm2 deletion during cardiac development resulted in significantly reduced cardiomyocyte cell cycle, cardiomyocyte numbers, and myocardial size. In addition, using cardiomyocyte-specific Pkm2 modified RNA, our novel cardiomyocyte-targeted strategy, after acute or chronic myocardial infarction, resulted in increased cardiomyocyte cell division, enhanced cardiac function, and improved long-term survival. We mechanistically show that Pkm2 regulates the cardiomyocyte cell cycle and reduces oxidative stress damage through anabolic pathways and β-catenin.

Conclusions: We demonstrate that Pkm2 is an important intrinsic regulator of the cardiomyocyte cell cycle and oxidative stress, and highlight its therapeutic potential using cardiomyocyte-specific Pkm2 modified RNA as a gene delivery platform.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.119.043067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7241614PMC
April 2020

Altering Sphingolipid Metabolism Attenuates Cell Death and Inflammatory Response After Myocardial Infarction.

Circulation 2020 03 29;141(11):916-930. Epub 2020 Jan 29.

Cardiovascular Research Center (Y.H., E.Y., M.M.Ż., E.C., N.S., M.T.K.S., R.K., A.A.K., K.K., A.M., N.H., L.Z., A.F, M.G.K.), Icahn School of Medicine at Mount Sinai, New York.

Background: Sphingolipids have recently emerged as a biomarker of recurrence and mortality after myocardial infarction (MI). The increased ceramide levels in mammalian heart tissues during acute MI, as demonstrated by several groups, is associated with higher cell death rates in the left ventricle and deteriorated cardiac function. Ceramidase, the only enzyme known to hydrolyze proapoptotic ceramide, generates sphingosine, which is then phosphorylated by sphingosine kinase to produce the prosurvival molecule sphingosine-1-phosphate. We hypothesized that Acid Ceramidase (AC) overexpression would counteract the negative effects of elevated ceramide and promote cell survival, thereby providing cardioprotection after MI.

Methods: We performed transcriptomic, sphingolipid, and protein analyses to evaluate sphingolipid metabolism and signaling post-MI. We investigated the effect of altering ceramide metabolism through a loss (chemical inhibitors) or gain (modified mRNA [modRNA]) of AC function post hypoxia or MI.

Results: We found that several genes involved in de novo ceramide synthesis were upregulated and that ceramide (C16, C20, C20:1, and C24) levels had significantly increased 24 hours after MI. AC inhibition after hypoxia or MI resulted in reduced AC activity and increased cell death. By contrast, enhancing AC activity via AC modRNA treatment increased cell survival after hypoxia or MI. AC modRNA-treated mice had significantly better heart function, longer survival, and smaller scar size than control mice 28 days post-MI. We attributed the improvement in heart function post-MI after AC modRNA delivery to decreased ceramide levels, lower cell death rates, and changes in the composition of the immune cell population in the left ventricle manifested by lowered abundance of proinflammatory detrimental neutrophils.

Conclusions: Our findings suggest that transiently altering sphingolipid metabolism through AC overexpression is sufficient and necessary to induce cardioprotection post-MI, thereby highlighting the therapeutic potential of AC modRNA in ischemic heart disease.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.119.041882DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7135928PMC
March 2020

AAV1.SERCA2a Gene Therapy Reverses Pulmonary Fibrosis by Blocking the STAT3/FOXM1 Pathway and Promoting the SNON/SKI Axis.

Mol Ther 2020 02 6;28(2):394-410. Epub 2019 Dec 6.

Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Electronic address:

Inhibition of pulmonary fibrosis (PF) by restoring sarco/endoplasmic reticulum calcium ATPase 2a isoform (SERCA2a) expression using targeted gene therapy may be a potentially powerful new treatment approach for PF. Here, we found that SERCA2a expression was significantly decreased in lung samples from patients with PF and in the bleomycin (BLM) mouse model of PF. In the BLM-induced PF model, intratracheal aerosolized adeno-associated virus serotype 1 (AAV1) encoding for human SERCA2a (AAV1.hSERCA2a) reduces lung fibrosis and associated vascular remodeling. SERCA2a gene therapy also decreases right ventricular pressure and hypertrophy in both prevention and curative protocols. In vitro, we observed that SERCA2a overexpression inhibits fibroblast proliferation, migration, and fibroblast-to-myofibroblast transition induced by transforming growth factor β (TGF-β1). Thus, pro-fibrotic gene expression is prevented by blocking nuclear factor κB (NF-κB)/interleukin-6 (IL-6)-induced signal transducer and activator of transcription 3 (STAT3) activation. This effect is signaled toward an inhibitory mechanism of small mother against decapentaplegic (SMAD)/TGF-β signaling through the repression of OTU deubiquitinase, ubiquitin aldehyde binding 1 (OTUB1) and Forkhead box M1 (FOXM1). Interestingly, this cross-inhibition leads to an increase of SKI and SnoN expression, an auto-inhibitory feedback loop of TGF-β signaling. Collectively, our results demonstrate that SERCA2a gene transfer attenuates bleomycin (BLM)-induced PF by blocking the STAT3/FOXM1 pathway and promoting the SNON/SKI Axis. Thus, SERCA2a gene therapy may be a potential therapeutic target for PF.
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http://dx.doi.org/10.1016/j.ymthe.2019.11.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7001085PMC
February 2020

Optimizing Modified mRNA Synthesis Protocol for Heart Gene Therapy.

Mol Ther Methods Clin Dev 2019 Sep 30;14:300-305. Epub 2019 Jul 30.

Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.

Synthetic modified RNA (modRNA) is a novel vector for gene transfer to the heart and other organs. modRNA can mediate strong, transient protein expression with minimal induction of the innate immune response and risk for genome integration. modRNA is already being used in several human clinical trials, and its use in basic and translational science is growing. Due to the complexity of preparing modRNA and the high cost of its reagents, there is a need for an improved, cost-efficient protocol to make modRNA. Here we show that changing the ratio between anti-reverse cap analog (ARCA) and N1-methyl-pseudouridine (N1mΨ), favoring ARCA over N1mΨ, significantly increases the yield per reaction, improves modRNA translation, and reduces its immunogenicity . This protocol will make modRNA preparation more accessible and financially affordable for basic and translational research.
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http://dx.doi.org/10.1016/j.omtm.2019.07.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6722299PMC
September 2019

Surgical and physiological challenges in the development of left and right heart failure in rat models.

Heart Fail Rev 2019 09;24(5):759-777

Cardiovascular Research Center, Department of Cardiology, Icahn School of Medicine at Mount Sinai, 1470 Madison Ave., Box 1030, New York, NY, 10029-6574, USA.

Rodent surgical animal models of heart failure (HF) are critically important for understanding the proof of principle of the cellular alterations underlying the development of the disease as well as evaluating therapeutics. Robust, reproducible rodent models are a prerequisite to the development of pharmacological and molecular strategies for the treatment of HF in patients. Due to the absence of standardized guidelines regarding surgical technique and clear criteria for HF progression in rats, objectivity is compromised. Scientific publications in rats rarely fully disclose the actual surgical details, and technical and physiological challenges. This lack of reporting is one of the main reasons that the outcomes specified in similar studies are highly variable and associated with unnecessary loss of animals, compromising scientific assessment. This review details rat circulatory and coronary arteries anatomy, the surgical details of rat models that recreate the HF phenotype of myocardial infarction, ischemia/reperfusion, left and right ventricular pressure, and volume overload states, and summarizes the technical and physiological challenges of creating HF. The purpose of this article is to help investigators understand the underlying issues of current HF models in order to reduce variable results and ensure successful, reproducible models of HF.
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http://dx.doi.org/10.1007/s10741-019-09783-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6698228PMC
September 2019

Cardiac Sca-1 Cells Are Not Intrinsic Stem Cells for Myocardial Development, Renewal, and Repair.

Circulation 2018 12;138(25):2919-2930

Riley Heart Research Center and Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis (L. Zhang, F.Y., C.-L.C.).

Background: For more than a decade, Sca-1 cells within the mouse heart have been widely recognized as a stem cell population with multipotency that can give rise to cardiomyocytes, endothelial cells, and smooth muscle cells in vitro and after cardiac grafting. However, the developmental origin and authentic nature of these cells remain elusive.

Methods: Here, we used a series of high-fidelity genetic mouse models to characterize the identity and regenerative potential of cardiac resident Sca-1 cells.

Results: With these novel genetic tools, we found that Sca-1 does not label cardiac precursor cells during early embryonic heart formation. Postnatal cardiac resident Sca-1 cells are in fact a pure endothelial cell population. They retain endothelial properties and exhibit minimal cardiomyogenic potential during development, normal aging and upon ischemic injury.

Conclusions: Our study provides definitive insights into the nature of cardiac resident Sca-1 cells. The observations challenge the current dogma that cardiac resident Sca-1 cells are intrinsic stem cells for myocardial development, renewal, and repair, and suggest that the mechanisms of transplanted Sca-1 cells in heart repair need to be reassessed.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.118.035200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6366943PMC
December 2018

Ablation of a Single N-Glycosylation Site in Human FSTL 1 Induces Cardiomyocyte Proliferation and Cardiac Regeneration.

Mol Ther Nucleic Acids 2018 Dec 1;13:133-143. Epub 2018 Sep 1.

Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Electronic address:

Adult mammalian hearts have a very limited regeneration capacity, due largely to a lack of cardiomyocyte (CM) proliferation. It was recently reported that epicardial, but not myocardial, follistatin-like 1 (Fstl1) activates CM proliferation and cardiac regeneration after myocardial infarction (MI). Furthermore, bacterially synthesized human FSTL 1 (hFSTL1) was found to induce CM proliferation, whereas hFSTL1 synthesized in mammals did not, suggesting that post-translational modifications (e.g., glycosylation) of the hFSTL1 protein affect its regenerative activity. We used modified mRNA (modRNA) technology to investigate the possible role of specific hFSTL1 N-glycosylation sites in the induction, by hFSTL1, of CM proliferation and cardiac regeneration. We found that the mutation of a single site (N180Q) was sufficient and necessary to increase the proliferation of rat neonatal and mouse adult CMs in vitro and after MI in vivo, respectively. A single administration of the modRNA construct encoding the N180Q mutant significantly increased cardiac function, decreased scar size, and increased capillary density 28 days post-MI. Overall, our data suggest that the delivery of N180Q hFSTL1 modRNA to the myocardium can mimic the beneficial effect of epicardial hFSTL1, triggering marked CM proliferation and cardiac regeneration in a mouse MI model.
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http://dx.doi.org/10.1016/j.omtn.2018.08.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6171324PMC
December 2018

FTO-Dependent N-Methyladenosine Regulates Cardiac Function During Remodeling and Repair.

Circulation 2019 01;139(4):518-532

Cardiovascular Research Center, Icahn School of Medicine, Mount Sinai, NY.

Background: Despite its functional importance in various fundamental bioprocesses, studies of N-methyladenosine (m6A) in the heart are lacking. Here, we show that the FTO (fat mass and obesity-associated protein), an m6A demethylase, plays a critical role in cardiac contractile function during homeostasis, remodeling, and regeneration.

Methods: We used clinical human samples, preclinical pig and mouse models, and primary cardiomyocyte cell cultures to study the functional role of m6A and FTO in the heart and in cardiomyocytes. We modulated expression of FTO by using adeno-associated virus serotype 9 (in vivo), adenovirus (both in vivo and in vitro), and small interfering RNAs (in vitro) to study its function in regulating cardiomyocyte m6A, calcium dynamics and contractility, and cardiac function postischemia. We performed methylated (m6A) RNA immunoprecipitation sequencing to map transcriptome-wide m6A, and methylated (m6A) RNA immunoprecipitation quantitative polymerase chain reaction assays to map and validate m6A in individual transcripts, in healthy and failing hearts, and in myocytes.

Results: We discovered that FTO has decreased expression in failing mammalian hearts and hypoxic cardiomyocytes, thereby increasing m6A in RNA and decreasing cardiomyocyte contractile function. Improving expression of FTO in failing mouse hearts attenuated the ischemia-induced increase in m6A and decrease in cardiac contractile function. This is performed by the demethylation activity of FTO, which selectively demethylates cardiac contractile transcripts, thus preventing their degradation and improving their protein expression under ischemia. In addition, we demonstrate that FTO overexpression in mouse models of myocardial infarction decreased fibrosis and enhanced angiogenesis.

Conclusions: Collectively, our study demonstrates the functional importance of the FTO-dependent cardiac m6A methylome in cardiac contraction during heart failure and provides a novel mechanistic insight into the therapeutic mechanisms of FTO.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.118.033794DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6400591PMC
January 2019

Optimizing Cardiac Delivery of Modified mRNA.

Mol Ther 2017 06 4;25(6):1306-1315. Epub 2017 Apr 4.

Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA; Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. Electronic address:

Modified mRNA (modRNA) is a new technology in the field of somatic gene transfer that has been used for the delivery of genes into different tissues, including the heart. Our group and others have shown that modRNAs injected into the heart are robustly translated into the encoded protein and can potentially improve outcome in heart injury models. However, the optimal compositions of the modRNA and the reagents necessary to achieve optimal expression in the heart have not been characterized yet. In this study, our aim was to elucidate those parameters by testing different nucleotide modifications, modRNA doses, and transfection reagents both in vitro and in vivo in cardiac cells and tissue. Our results indicate that optimal cardiac delivery of modRNA is with N1-Methylpseudouridine-5'-Triphosphate nucleotide modification and achieved using 0.013 μg modRNA/mm/500 cardiomyocytes (CMs) transfected with positively charged transfection reagent in vitro and 100 μg/mouse heart (1.6 μg modRNA/μL in 60 μL total) sucrose-citrate buffer in vivo. We have optimized the conditions for cardiac delivery of modRNA in vitro and in vivo. Using the described methods and conditions may allow for successful gene delivery using modRNA in various models of cardiovascular disease.
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http://dx.doi.org/10.1016/j.ymthe.2017.03.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5474881PMC
June 2017

Ablation Is Associated With Increased Nitro-Oxidative Stress During Ischemia-Reperfusion Injury: Implications for Human Ischemic Cardiomyopathy.

Circ Heart Fail 2017 Feb;10(2)

From the Division of Cardiovascular Medicine, Davis Heart and Lung Research Institute (B.Z., D.G.W., Z.X., R.H., H.H., S.V., J.L.Z.), Department of Physiology and Cell Biology (B.Z., J.L.Z., M.J.K., M.T.Z.), The Ohio State University, Columbus; Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, HuBei, China (B.Z.); Department of Biostatistics (Y.S., M.X., F.E.H.), Division of Clinical Pharmacology, Department of Medicine (D.M.R., C.M.S.), Division of Cardiac Surgery, Department of Surgery (T.A.), Division of Cardiovascular Medicine (T. N., E. C., Y.R.S., D.R., C.L.G., Q.S.W, R.J.G.), Department of Pharmacology and Department of Pathology, Immunology, and Microbiology (R.J.G.), Vanderbilt University Medical Center, Nashville, TN.

Background: Despite increased secondary cardiovascular events in patients with ischemic cardiomyopathy (ICM), the expression of innate cardiac protective molecules in the hearts of patients with ICM is incompletely characterized. Therefore, we used a nonbiased RNAseq approach to determine whether differences in cardiac protective molecules occur with ICM.

Methods And Results: RNAseq analysis of human control and ICM left ventricular samples demonstrated a significant decrease in expression with ICM. encodes the Kir6.2 subunit of the cardioprotective K channel. Using wild-type mice and -deficient (-null) mice, we examined the effect of expression on cardiac function during ischemia-reperfusion injury. Reactive oxygen species generation increased in -null hearts above that found in wild-type mice hearts after ischemia-reperfusion injury. Continuous left ventricular pressure measurement during ischemia and reperfusion demonstrated a more compromised diastolic function in -null compared with wild-type mice during reperfusion. Analysis of key calcium-regulating proteins revealed significant differences in -null mice. Despite impaired relaxation, -null hearts increased phospholamban Ser16 phosphorylation, a modification that results in the dissociation of phospholamban from sarcoendoplasmic reticulum Ca, thereby increasing sarcoendoplasmic reticulum Ca-mediated calcium reuptake. However, -null mice also had increased 3-nitrotyrosine modification of the sarcoendoplasmic reticulum Ca-ATPase, a modification that irreversibly impairs sarcoendoplasmic reticulum Ca function, thereby contributing to diastolic dysfunction.

Conclusions: expression is decreased in human ICM. Lack of expression increases peroxynitrite-mediated modification of the key calcium-handling protein sarcoendoplasmic reticulum Ca-ATPase after myocardial ischemia-reperfusion injury, contributing to impaired diastolic function. These data suggest a mechanism for ischemia-induced diastolic dysfunction in patients with ICM.
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http://dx.doi.org/10.1161/CIRCHEARTFAILURE.116.003523DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319711PMC
February 2017

Insulin-Like Growth Factor 1 Receptor-Dependent Pathway Drives Epicardial Adipose Tissue Formation After Myocardial Injury.

Circulation 2017 Jan 1;135(1):59-72. Epub 2016 Nov 1.

From Cardiovascular Research Center, Department of Genetics and Genomic Sciences, and Black Family Stem Cell Institute, Icahn School of Medicine at Mount Sinai, New York (L.Z., N.S., Y.H.); Department of Cardiology, Boston Children's Hospital, MA (L.Z., M.S.O., L.Y.Y., Q.M., W.T.P.); Cardiovascular and Metabolic Diseases Innovative Medicine Biotech Unit, AstraZeneca, Möllndal, Sweden (D.S., Q.-D.W.); The State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences (B.Z.); Department of Genetics (W.L.C.), Harvard Stem Cell Institute (W.E., W.T.P.), Harvard Medical School, and Cardiovascular Research Center, Massachusetts General Hospital (M.A.), Harvard Medical School, Boston, MA; and Department of Cell and Molecular Biology and Medicine, Karolinska Institutet, Stockholm, Sweden (K.R.C.).

Background: Epicardial adipose tissue volume and coronary artery disease are strongly associated, even after accounting for overall body mass. Despite its pathophysiological significance, the origin and paracrine signaling pathways that regulate epicardial adipose tissue's formation and expansion are unclear.

Methods: We used a novel modified mRNA-based screening approach to probe the effect of individual paracrine factors on epicardial progenitors in the adult heart.

Results: Using 2 independent lineage-tracing strategies in murine models, we show that cells originating from the Wt1 mesothelial lineage, which includes epicardial cells, differentiate into epicardial adipose tissue after myocardial infarction. This differentiation process required Wt1 expression in this lineage and was stimulated by insulin-like growth factor 1 receptor (IGF1R) activation. IGF1R inhibition within this lineage significantly reduced its adipogenic differentiation in the context of exogenous, IGF1-modified mRNA stimulation. Moreover, IGF1R inhibition significantly reduced Wt1 lineage cell differentiation into adipocytes after myocardial infarction.

Conclusions: Our results establish IGF1R signaling as a key pathway that governs epicardial adipose tissue formation in the context of myocardial injury by redirecting the fate of Wt1 lineage cells. Our study also demonstrates the power of modified mRNA -based paracrine factor library screening to dissect signaling pathways that govern progenitor cell activity in homeostasis and disease.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.116.022064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5195872PMC
January 2017

Impact of cardiac-specific expression of CD39 on myocardial infarct size in mice.

Life Sci 2017 Jun 15;179:54-59. Epub 2016 Oct 15.

Division of Cardiovascular Medicine, Vanderbilt University, Nashville, TN, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN, USA; Department of Pathology, Immunology and Microbiology, Vanderbilt University, Nashville, TN, USA. Electronic address:

Aims: Prior work suggests that ischemic preconditioning increases the level of CD39 in the heart and contributes to cardiac protection. Therefore, we examined if targeted cardiac expression of CD39 protects against myocardial injury.

Main Methods: Mice with cardiac-specific expression of human CD39 (αMHC/hCD39-Tg) were generated, characterized and subjected to left coronary artery ischemia-reperfusion injury and infarct size at 24h following injury quantified.

Key Findings: αMHC/hCD39-Tg mice have increased in cardiac ATPase and ADPase activity compared to WT littermates. The increased activity in αMHC/hCD39-mice was inhibited by the CD39 antagonist sodium polyoxotungstate (POM-1). Measurement of basal cardiac function by echocardiography revealed that αMHC/hCD39-Tg mice have a lower resting heart rate and increased stroke volume. In response to myocardial ischemia, systolic and diastolic function was better preserved in αMHC/hCD39-Tg compared to WT mice. Comparison of Tau also revealed preserved cardiac relaxation during ischemia in αMHC/hCD39-Tg hearts. Assessment of myocardial infarct size in response to 60min of ischemia and 24h of reperfusion demonstrated a significant reduction in infarct size in αMHC/hCD39-Tg hearts. Analysis of isolated cardiomyocytes revealed no basal difference in calcium transients between WT and αMHC/hCD39-Tg cardiomyocytes. However, in response to isoproterenol stimulation, there was a trend toward lower calcium transients in αMHC/hCD39 cardiomyocytes suggesting less calcium accumulation in response to metabolic stress.

Significance: Cardiac-specific expression of CD39 reduces myocardial dysfunction and infarct size following ischemia-reperfusion injury. Increasing nucleotidase expression in the heart may be a novel approach to protect the heart from ischemic injury.
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http://dx.doi.org/10.1016/j.lfs.2016.10.016DOI Listing
June 2017

Role of the CD39/CD73 Purinergic Pathway in Modulating Arterial Thrombosis in Mice.

Arterioscler Thromb Vasc Biol 2016 09 14;36(9):1809-20. Epub 2016 Jul 14.

From the Division of Cardiovascular Medicine, Department of Medicine (R.C., E.C., T.N., R.J.G.), Department of Pharmacology (R.J.G.), and Department of Pathology Microbiology and Immunology (R.J.G.), Vanderbilt University, Nashville, TN; Division of Cardiovascular Medicine, Davis Heart and Lung Research Institute, The Ohio State University, Columbus (A.R., Z.M.H., R.H., K.S., D.G.W.); Transplant Institute, Department of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA (S.C.R.); School of Medicine, Deakin University (K.M.D., P.J.C.); Immunology Research Centre, St. Vincent's Hospital (K.M.D.); and Department of Medicine, University of Melbourne, Victoria, Australia (K.M.D., P.J.C.).

Objective: Circulating blood cells and endothelial cells express ectonucleoside triphosphate diphosphohydrolase-1 (CD39) and ecto-5'-nucleotidase (CD73). CD39 hydrolyzes extracellular ATP or ADP to AMP. CD73 hydrolyzes AMP to adenosine. The goal of this study was to examine the interplay between CD39 and CD73 cascade in arterial thrombosis.

Approach And Results: To determine how CD73 activity influences in vivo thrombosis, the time to ferric chloride-induced arterial thrombosis was measured in CD73-null mice. In response to 5% FeCl3, but not to 10% FeCl3, there was a significant decrease in the time to thrombosis in CD73-null mice compared with wild-type mice. In mice overexpressing CD39, ablation of CD73 did not inhibit the prolongation in the time to thrombosis conveyed by CD39 overexpression. However, the CD73 inhibitor α-β-methylene-ADP nullified the prolongation in the time to thrombosis in human CD39 transgenic (hC39-Tg)/CD73-null mice. To determine whether hematopoietic-derived cells or endothelial cell CD39 activity regulates in vivo arterial thrombus, bone marrow transplant studies were conducted. FeCl3-induced arterial thrombosis in chimeric mice revealed a significant prolongation in the time to thrombosis in hCD39-Tg reconstituted wild-type mice, but not on wild-type reconstituted hCD39-Tg mice. Monocyte depletion with clodronate-loaded liposomes normalized the time to thrombosis in hCD39-Tg mice compared with hCD39-Tg mice treated with control liposomes, demonstrating that increased CD39 expression on monocytes protects against thrombosis.

Conclusions: These data demonstrate that ablation of CD73 minimally effects in vivo thrombosis, but increased CD39 expression on hematopoietic-derived cells, especially monocytes, attenuates in vivo arterial thrombosis.
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http://dx.doi.org/10.1161/ATVBAHA.116.307374DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5206760PMC
September 2016

Extracellular nucleotide regulation and signaling in cardiac fibrosis.

J Mol Cell Cardiol 2016 04 16;93:47-56. Epub 2016 Feb 16.

Division of Cardiovascular Medicine, Vanderbilt University, Nashville, TN, USA; Department of Pharmacology, Vanderbilt University, Nashville, TN, USA; Department of Pathology, Immunology and Microbiology, Vanderbilt University, Nashville, TN, USA. Electronic address:

Following myocardial infarction, purinergic nucleotides and nucleosides are released via non-specific and specific mechanisms in response to cellular activation, stress, or injury. These extracellular nucleotides are potent mediators of physiologic and pathologic responses, contributing to the inflammatory and fibrotic milieu within the injured myocardium. Via autocrine or paracrine signaling, cell-specific effects occur through differentially expressed purinergic receptors of the P2X, P2Y, and P1 families. Nucleotide activation of the ionotropic (ligand-gated) purine receptors (P2X) and several of the metabotropic (G-protein-coupled) purine receptors (P2Y) or adenosine activation of the P1 receptors can have profound effects on inflammatory cell function, fibroblast function, and cardiomyocyte function. Extracellular nucleotidases that hydrolyze released nucleotides regulate the magnitude and duration of purinergic signaling. While there are numerous studies on the role of the purinergic signaling pathway in cardiovascular disease, the extent to which the purinergic signaling pathway modulates cardiac fibrosis is incompletely understood. Here we provide an overview of the current understanding of how the purinergic signaling pathway modulates cardiac fibroblast function and myocardial fibrosis.
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http://dx.doi.org/10.1016/j.yjmcc.2016.02.010DOI Listing
April 2016

The association between let-7, RAS and HIF-1α in Ewing Sarcoma tumor growth.

Oncotarget 2015 Oct;6(32):33834-48

Molecular Oncology, Felsenstein Medical Research Center, Rabin Medical Center, Petah Tikva, Israel.

Ewing Sarcoma (ES) is the second most common primary malignant bone tumor in children and adolescents. microRNAs (miRNAs) are involved in cancer as tumor suppressors or oncogenes. We studied the involvement of miRNAs located on chromosomes 11q and 22q that participate in the most common translocation in ES. Of these, we focused on 3 that belong to the let-7 family.We studied the expression levels of let-7a, and let-7b and detected a significant correlation between low expression of let-7b and increased risk of relapse. let-7 is known to be a negative regulator of the RAS oncogene. Indeed, we detected an inverse association between the expression of let-7 and RAS protein levels and its downstream target p-ERK, following transfection of let-7 mimics and inhibitors. Furthermore, we identified let-7 as a negative regulator of HIF-1α and EWS-FLI-1. Moreover, we were able to show that HIF-1α directly binds to the EWS-FLI-1 promoter. Salirasib treatment in-vitro resulted in the reduction of cell viability, migration ability, and in the decrease of cells in S-phase. A significant reduction in tumor burden and in the expression levels of both HIF-1α and EWS-FLI-1 proteins were observed in mice after treatment.Our results support the hypothesis that let-7 is a tumor suppressor that negatively regulates RAS, also in ES, and that HIF-1α may contribute to the aggressive metastatic behavior of ES. Moreover, the reduction in the tumor burden in a mouse model of ES following Salirasib treatment, suggests therapeutic potential for this RAS inhibitor in ES.
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http://dx.doi.org/10.18632/oncotarget.5616DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4741806PMC
October 2015

Glucagon-like peptide-1 reduces hepatic lipogenesis via activation of AMP-activated protein kinase.

J Hepatol 2011 Jun 26;54(6):1214-23. Epub 2010 Oct 26.

Department of Gastroenterology and Hepatology, Tel Aviv Sourasky Medical Center, and Sackler School of Medicine, Tel Aviv, Israel.

Background & Aims: Glucagon-like peptide-1 (GLP-1), a gut-derived peptide degraded by dipeptidyl peptidase-4 (DPP4), stimulates insulin secretion in response to nutrients, yet its direct effect on the liver is controversial. We investigated the effects of GLP-1 on hepatic fat and glucose metabolism and elucidated its mechanism of action.

Methods: Hepatic fat metabolism, including lipogenic enzymes and signal transduction regulators, was assessed in livers of DPP4-deficient rats (DPP4-) with chronically elevated GLP-1 and in GLP-1-treated primary hepatocytes. The effect of chronic elevated GLP-1 on insulin sensitivity was measured using the hyperinsulinemic-euglycemic clamp.

Results: Normal and high fat diet fed DPP4-rats displayed reduced hepatic triglycerides, accompanied by down-regulation of lipogenesis enzymes and parallel up-regulation of carnitine palmitoyltransferase-1, a key enzyme in fatty acid β-oxidation. In vitro studies demonstrated that these effects were directly induced by GLP-1. Mechanistically, GLP-1 increased cAMP in hepatocytes, resulting in the phosphorylation of cAMP-activated protein kinase (AMPK), a suppressor of lipogenesis. Indeed, hepatocytes expressing a dominant negative Ad-DN-AMPK displayed attenuated GLP-1 effects on AMPK phosphorylation and its downstream lipogenic targets. Importantly, normoglycemic DPP4-rats did not display improved hepatic insulin sensitivity in vivo, suggesting a direct effect of GLP-1 on fat metabolism. Finally, DPP4-rats expressed lower levels of hepatic proinflammatory and profibrotic cytokines in response to nutrient stimuli.

Conclusions: GLP-1 suppresses hepatic lipogenesis via activation of the AMPK pathway. GLP-1 inhibitory effects on hepatic fat accumulation and nutrient-induced hepatic proinflammatory response suggest GLP-1 analogs as novel therapies for non-alcoholic fatty liver diseases.
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http://dx.doi.org/10.1016/j.jhep.2010.09.032DOI Listing
June 2011
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