Abstract P325: The Role Of Runx1 In Cardiomyocyte Cell Cycle And Ploidy

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Samantha K Swift ◽  
Michaela Patterson
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Heart Development ◽  
Cardiac Injury ◽  
Cardiac Regeneration ◽  
Cardiac Conduction ◽  
Calcium Handling ◽  
Mouse Heart ◽  
Disease States ◽  
Eccentric Hypertrophy

Adult mammalian cardiomyocytes (CMs) are thought to be post-mitotic and therefore unable to regenerate the myocardium after injury. In recent years various studies have shown that the adult mammalian CM is capable of a small amount of proliferation, potentially restricted to a subset of CMs. One such study demonstrated that having greater percentages of the rare mononuclear diploid cardiomyocyte (MNDCM) is associated with improved outcomes after myocardial infarction (MI). An accompanying genome-wide association analysis identified genetic loci associated with the frequency of the MNDCM population. One candidate to come out of this screen was Runx1. Concurrently, RUNX1 captured the attention of cardiac regeneration researchers due to its increased presence in disease states, with some suggesting it may be a marker for dedifferentiation (fetal gene induction). One recent study demonstrated improved calcium handling and decreased eccentric hypertrophy following RUNX1 ablation after injury, perhaps corroborating the idea that RUNX1 is involved with CM dedifferentiation. We hypothesize that Runx1 influences dedifferentiation in CMs, impacting ploidy, as well as CM cell cycle activity and post-MI outcomes. We found that CM-specific overexpression (OE) of Runx1 results in a doubling of the MNDCM population, thereby validating its influence on the population. Via multiple contexts including postnatal development and adult injury, knocking out Runx1 decreases DNA synthesis while Runx1 OE increases DNA synthesis. Furthermore, an initial analysis of RNAseq data demonstrates that RUNX1 OE in a neonatal mouse hearts demonstrated differential expression in genes related to cardiac conduction, contraction, heart development, regeneration, and regulation of cell differentiation . After MI in the adult mouse heart, the effects of Runx1 OE resulted in transient benefits which included increased cell cycle activity and preservation of function. These data suggest that Runx1 is not simply a marker of CM dedifferentiation, but also a regulator of the process including cell cycle activation. Ongoing work will tease apart this role in more detail and could establish RUNX1 as a prominent therapeutic target for mitigating effects of cardiac injury.

scholarly journals Molecular atlas of postnatal mouse heart development

2018 ◽  
Author(s):  
Virpi Talman ◽  
Jaakko Teppo ◽  
Päivi Pöhö ◽  
Parisa Movahedi ◽  
Anu Vaikkinen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Heart Development ◽  
Molecular Mechanisms ◽  
Mevalonate Pathway ◽  
Cardiac Regeneration ◽  
Neonatal Rat ◽  
Acid Oxidation ◽  
Mouse Heart ◽  
Tissue Samples ◽  
Combining Data

AbstractRationaleMammals lose the ability to regenerate their hearts within one week after birth. During this regenerative window, cardiac energy metabolism shifts from glycolysis to fatty acid oxidation, and recent evidence suggests that metabolism may participate in controlling cardiomyocyte cell cycle. However, the molecular mechanisms mediating the loss of postnatal cardiac regeneration are not fully understood.ObjectiveThis study aims at providing an integrated resource of mRNA, protein and metabolite changes in the neonatal heart to identify metabolism-related mechanisms associated with the postnatal loss of regenerative capacity.Methods and ResultsMouse ventricular tissue samples taken on postnatal days 1, 4, 9 and 23 (P01, P04, P09 and P23, respectively) were analyzed with RNA sequencing (RNAseq) and global proteomics and metabolomics. Differential expression was observed for 8547 mRNAs and for 1199 of the 2285 quantified proteins. Furthermore, 151 metabolites with significant changes were identified. Gene ontology analysis, KEGG pathway analysis and fuzzy c-means clustering were used to identify biological processes and metabolic pathways either up- or downregulated on all three levels. Among these were branched chain amino acid degradation (upregulated at P23) and production of free saturated and monounsaturated medium- to long-chain fatty acids (upregulated at P04 and P09; downregulated at P23). Moreover, the HMG-CoA synthase (HMGCS)-mediated mevalonate pathway and ketogenesis were transiently activated. Pharmacological inhibition of HMGCS in primary neonatal rat ventricular cardiomyocytes reduced the percentage of BrdU+ cardiomyocytes, providing evidence that the mevalonate and ketogenesis routes may participate in regulating cardiomyocyte cell cycle.ConclusionsThis is the first systems-level resource combining data from genome-wide transcriptomics with global quantitative proteomics and untargeted metabolomics analyses of the mouse heart throughout the early postnatal period. This integrated multi-level data of molecular changes associated with the loss of cardiac regeneration may open up new possibilities for the development of regenerative therapies.

scholarly journals The Evolving Roles of Cardiac Macrophages in Homeostasis, Regeneration, and Repair

2021 ◽  
Vol 22 (15) ◽  
pp. 7923
Author(s):  
Santiago Alvarez-Argote ◽  
Caitlin C. O’Meara
Keyword(s):  
Cardiac Injury ◽  
Cardiac Regeneration ◽  
Normal Function ◽  
Cardiac Conduction ◽  
Cell Detection ◽  
Fate Mapping ◽  
The Novel ◽  
Functional Roles ◽  
Macrophage Populations ◽  
And Function

Macrophages were first described as phagocytic immune cells responsible for maintaining tissue homeostasis by the removal of pathogens that disturb normal function. Historically, macrophages have been viewed as terminally differentiated monocyte-derived cells that originated through hematopoiesis and infiltrated multiple tissues in the presence of inflammation or during turnover in normal homeostasis. However, improved cell detection and fate-mapping strategies have elucidated the various lineages of tissue-resident macrophages, which can derive from embryonic origins independent of hematopoiesis and monocyte infiltration. The role of resident macrophages in organs such as the skin, liver, and the lungs have been well characterized, revealing functions well beyond a pure phagocytic and immunological role. In the heart, recent research has begun to decipher the functional roles of various tissue-resident macrophage populations through fate mapping and genetic depletion studies. Several of these studies have elucidated the novel and unexpected roles of cardiac-resident macrophages in homeostasis, including maintaining mitochondrial function, facilitating cardiac conduction, coronary development, and lymphangiogenesis, among others. Additionally, following cardiac injury, cardiac-resident macrophages adopt diverse functions such as the clearance of necrotic and apoptotic cells and debris, a reduction in the inflammatory monocyte infiltration, promotion of angiogenesis, amelioration of inflammation, and hypertrophy in the remaining myocardium, overall limiting damage extension. The present review discusses the origin, development, characterization, and function of cardiac macrophages in homeostasis, cardiac regeneration, and after cardiac injury or stress.

Abstract 127: Mode of Injury Affects the Course of Regeneration and Repair in Neonatal and Adult Mouse Heart

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Tal Konfino ◽  
Natalie Landa-Rouben ◽  
Jonathan Leor
Keyword(s):  
Granulation Tissue ◽  
Adult Mouse ◽  
Cardiac Injury ◽  
Cardiac Regeneration ◽  
Lv Function ◽  
Mouse Heart ◽  
Coronary Artery Ligation ◽  
Artery Ligation ◽  
Newborn Mice ◽  
Adult Mice

PURPOSE: Recent reports have demonstrated complete cardiac regeneration in newborn mice following resection of the cardiac apex. However, different types of injury could affect the mechanism of regeneration and repair. HYPOTHESIS: We aimed to test the hypothesis that the course of repair and regeneration after MI is different from apical resection in both neonatal and adult mouse heart. Methods and Results: Apical resection or permanent LAD coronary artery ligation was induced in 1-day-old or 12-week-old ICR mice. Echocardiography was used to confirm and monitor cardiac injury and remodeling. Mice were euthanized at different time points after operation, and hearts were harvested, processed, immunostained and compared with sham operated neonatal and adult hearts. Histological and immunohistochemical examination of both resected and infarcted neonatal hearts revealed inflammation and granulation tissue formation within 3 to 5 days. In the resected hearts, early regeneration was identified at the injured sites, and marked dedifferentiation of cardiomyocytes, represented by sarcomeric disassembly and marginalization, was evident around the injured areas. In addition, we noticed intensive proliferation of young cardiomyocytes which infiltrated the granulation tissue and formed a new myocardium within 21 days. In contrast, incomplete regeneration with residual small infract was detected 28 days after coronary occlusion. Echocardiography at 2,7,14 and 28 days after MI confirmed deteriorating LV function and LV remodeling with apical aneurysm formation. Surprisingly, 21 days after cardiac injury in adult mice, MI produced typical, thin, fibrotic scar whereas apical resection produced an apical tumor-like thick scar. Conclusions: The mode of injury, whether resection or infarction, affect regeneration and repair in both neonatal and adult mouse heart. Particularly, after apical resection, the newborn heart almost completely regenerates whereas regeneration is incomplete after MI, suggesting that infarction and subsequent inflammation might inhibit complete regeneration. Understanding these differences could be translated to development of new approaches to induce myocardial regeneration in adult heart.

scholarly journals Cell Cycle–Mediated Cardiac Regeneration in the Mouse Heart

2019 ◽  
Vol 21 (10) ◽  
Author(s):  
Arash Eghbali ◽  
Austin Dukes ◽  
Karl Toischer ◽  
Gerd Hasenfuss ◽  
Loren J. Field
Keyword(s):  
Cell Cycle ◽  
Cardiac Regeneration ◽  
Mouse Heart

scholarly journals Mononuclear diploid cardiomyocytes support neonatal mouse heart regeneration in response to paracrine IGF2 signaling

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Hua Shen ◽  
Peiheng Gan ◽  
Kristy Wang ◽  
Ali Darehzereshki ◽  
Kai Wang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Insulin Receptor ◽  
Heart Development ◽  
Postnatal Period ◽  
Mouse Heart ◽  
Heart Regeneration ◽  
Newborn Mouse ◽  
Cell Cycle Entry ◽  
Additional Cell

Injury to the newborn mouse heart is efficiently regenerated, but this capacity is lost by one week after birth. We found that IGF2, an important mitogen in heart development, is required for neonatal heart regeneration. IGF2 originates from the endocardium/endothelium and is transduced in cardiomyocytes by the insulin receptor. Following injury on postnatal day 1, absence of IGF2 abolished injury-induced cell cycle entry during the early part of the first postnatal week. Consequently, regeneration failed despite the later presence of additional cell cycle-inducing activities 7 days following injury. Most cardiomyocytes transition from mononuclear diploid to polyploid during the first postnatal week. Regeneration was rescued in Igf2-deficient neonates in three different contexts that elevate the percentage of mononuclear diploid cardiomyocytes beyond postnatal day 7. Thus, IGF2 is a paracrine-acting mitogen for heart regeneration during the early postnatal period, and IGF2-deficiency unmasks the dependence of this process on proliferation-competent mononuclear diploid cardiomyocytes.

Abstract 548: Cellular Contributions to Neonatal Cardiac Regeneration

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Adwiteeya Misra ◽  
Pearl J Quijada ◽  
Ryan Burke ◽  
Ronald Dirkx ◽  
Eric M Small
Keyword(s):  
Rna Sequencing ◽  
Troponin T ◽  
Cardiac Injury ◽  
Cardiac Regeneration ◽  
Cardiac Repair ◽  
Mouse Heart ◽  
Sequencing Data ◽  
Injury Response ◽  
Virus Serotype

While the neonatal mouse heart possesses a remarkable ability to regenerate up to a week after birth, the adult mammalian heart is susceptible to irreversible scar formation that impedes cardiac function. Such a scar is formed by the precocious deposition of extracellular matrix (ECM) by resident cardiac fibroblasts (CFs). Unlike their adult counterparts, neonatal CFs in the regenerative widow may have a unique phenotype that contributes to cardiac regeneration and scar resolution. Indeed, the neonatal cardiac ECM secreted by CFs is reported to stimulate regeneration, yet the underlying mechanisms of CF-mediated cardiac repair in the neonate has not been examined. Here, we present a strategy to establish the role of tissue resident CFs in mouse neonatal cardiac regeneration through selective cell depletion and RNA sequencing. Through the initial analysis of published RNA sequencing data, we identified an enrichment of pro-regenerative molecules such as amphiregulin (Areg) during the neonatal regenerative window. Areg, an epidermal growth factor ligand, has been shown to paradoxically stimulate both cardiac repair and pathological fibrosis after adult cardiac injury. To assess its impact on the neonatal cardiac injury response, we developed an adeno-associated virus serotype 9 with the complete coding sequence of mouse Areg (AAV9:Areg) controlled by the cardiomyocyte-specific cardiac troponin T promoter. In vivo , AAV9:Areg treated mice accumulate BrdU+ (proliferative) non-myocytes adjacent to Areg-expressing cardiomyocytes. Ongoing studies are aimed at evaluating the contribution of CFs to neonatal cardiac repair, including whether Areg-dependent cellular changes impact CFs in the neonatal regenerative window in a manner distinct from that in the adult injury response.

scholarly journals Re-enforcing hypoxia-induced polyploid cardiomyocytes enter cytokinesis through activation of β-catenin

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yun-Han Jiang ◽  
Yu Zhu ◽  
Sai Chen ◽  
Hai-Long Wang ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Heart Disease ◽  
Epithelial Cell ◽  
Potential Field ◽  
Heart Development ◽  
Heart Diseases ◽  
Cardiac Regeneration ◽  
Related Factor ◽  
Promising Strategy ◽  
Cell Transforming

AbstractCardiomyocyte (CM) loss is a characteristic of various heart diseases, including ischaemic heart disease. Cardiac regeneration has been suggested as a promising strategy to address CM loss. Although many studies of regeneration have focused mainly on mononucleated or diploid CM, the limitations associated with the cytokinesis of polyploid and multinucleated CMs remain less well known. Here, we show that β-catenin, a key regulator in heart development, can increase cytokinesis in polyploid multinucleated CMs. The activation of β-catenin increases the expression of the cytokinesis-related factor epithelial cell transforming 2 (ECT2), which regulates the actomyosin ring and thus leads to the completion of cytokinesis in polyploid CMs. In addition, hypoxia can induce polyploid and multinucleated CMs by increasing factors related to the G1-S-anaphase of the cell cycle, but not those related to cytokinesis. Our study therefore reveals that the β-catenin can promote the cytokinesis of polyploid multinucleated CMs via upregulation of ECT2. These findings suggest a potential field of polyploid CM research that may be exploitable for cardiac regeneration therapy.

scholarly journals Pkm2 Regulates Cardiomyocyte Cell Cycle and Promotes Cardiac Regeneration

Circulation ◽  
2020 ◽  
Vol 141 (15) ◽  
pp. 1249-1265 ◽  
Author(s):  
Ajit Magadum ◽  
Neha Singh ◽  
Ann Anu Kurian ◽  
Irsa Munir ◽  
Talha Mehmood ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Myocardial Infarction ◽  
Cell Cycle ◽  
Pyruvate Kinase ◽  
Heart Development ◽  
Cardiac Development ◽  
Therapeutic Potential ◽  
Cardiac Regeneration ◽  
Chronic Myocardial Infarction ◽  
Term Survival

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.

scholarly journals Role of Podoplanin-Positive Cells in Cardiac Fibrosis and Angiogenesis After Ischemia

2021 ◽  
Vol 12 ◽  
Author(s):  
Maria Cimini ◽  
Raj Kishore
Keyword(s):  
Heart Development ◽  
Neutralizing Antibodies ◽  
Wound Repair ◽  
Cardiac Fibrosis ◽  
Inflammatory Responses ◽  
Heart Function ◽  
Cardiac Injury ◽  
Mouse Heart ◽  
Alternative Mechanism

New insights into the cellular and extra-cellular composition of scar tissue after myocardial infarction (MI) have been identified. Recently, a heterogeneous podoplanin-expressing cell population has been associated with fibrogenic and inflammatory responses and lymphatic vessel growth during scar formation. Podoplanin is a mucin-like transmembrane glycoprotein that plays an important role in heart development, cell motility, tumorigenesis, and metastasis. In the adult mouse heart, podoplanin is expressed only by cardiac lymphatic endothelial cells; after MI, it is acquired with an unexpected heterogeneity by PDGFRα-, PDGFRβ-, and CD34-positive cells. Podoplanin may therefore represent a sign of activation of a cohort of progenitor cells during different phases of post-ischemic myocardial wound repair. Podoplanin binds to C-type lectin-like receptor 2 (CLEC-2) which is exclusively expressed by platelets and a variety of immune cells. CLEC-2 is upregulated in CD11bhigh cells, including monocytes and macrophages, following inflammatory stimuli. We recently published that inhibition of the interaction between podoplanin-expressing cells and podoplanin-binding cells using podoplanin-neutralizing antibodies reduces but does not fully suppress inflammation post-MI while improving heart function and scar composition after ischemic injury. These data support an emerging and alternative mechanism of interactome in the heart that, when neutralized, leads to altered inflammatory response and preservation of cardiac function and structure. The overarching objective of this review is to assimilate and discuss the available evidence on the functional role of podoplanin-positive cells on cardiac fibrosis and remodeling. A detailed characterization of cell-to-cell interactions and paracrine signals between podoplanin-expressing cells and the other type of cells that compose the heart tissue is needed to open a new line of investigation extending beyond the known function of these cells. This review attempts to discuss the role and biology of podoplanin-positive cells in the context of cardiac injury, repair, and remodeling.

Abstract 550: FOG2 Modulates a TBX5-Dependent Gene Regulatory Network for Cardiac Rhythm Homeostasis

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Sonja Lazarevic ◽  
Michael Broman ◽  
Rangarajan Nadadur ◽  
Jeff Steimle ◽  
Brigitte Laforest ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Gene Regulatory Network ◽  
Regulatory Network ◽  
Cardiac Rhythm ◽  
Regulatory Elements ◽  
Cardiac Conduction ◽  
Calcium Handling ◽  
Mouse Heart ◽  
Gene Regulatory ◽  
Atrial Rhythm

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Recent work has implicated numerous transcription factors in AF risk, including ZFPM2 (FOG2), GATA4, and TBX5. FOG2 is overexpressed in human heart failure, a major AF risk factor. We found that genetic inducible physiologic overexpression of FOG2 in the adult mouse heart caused spontaneous atrial fibrillation. Single cell electrophysiology revealed action potential prolongation and inappropriate depolarizations in FOG2-OE atrial cardiomyocytes. RNA-seq of the FOG2-OE left atrium prior to AF onset demonstrated that FOG2 suppresses a network of calcium cycling genes, providing a possible mechanism for disrupted cardiomyocyte electrophysiology. FOG2 ChIP-seq demonstrated genomic localization only at locations co-occupied by GATA4. Unexpectedly, we observed little overlap between genes activated by GATA4 and repressed by FOG2. Instead, we observed highly significant overlap between genes repressed by FOG2 and activated by TBX5. To identify the FOG2-dependent atrial gene regulatory network, we performed differential deep sequencing of ncRNAs. Comparison of atrial FOG2-dependent non-coding transcripts with previously performed TBX5-dependent ncRNA profiling indicated that TBX5 activated and FOG2 repressed a shared atrial rhythm gene regulatory network. Integration of FOG2, GATA4, and TBX5 ChIP-seq revealed that FOG2 only affected ncRNA transcription, indicative of enhancer activity changes, at locations co-occupied by TBX5. TBX5-dependent activation of specific regulatory elements for calcium handling genes was abolished by FOG2 in vitro . The genomic TBX5/FOG2 interaction predicted a genetic interaction in-vivo , in which cardiac conduction and arrhythmia abnormalities caused by Tbx5 haploinsufficiency were rescued by FOG2 haploinsufficiency. Non-coding RNA profiling thereby predicted a novel functional TF interaction between FOG2 and TBX5. This work reveals a specific genomic model of atrial rhythm control in which FOG2 is recruited to GATA4 and TBX5 bound locations to modulate a TBX5-dependent atrial gene regulatory network for calcium handling and cardiac rhythm homeostasis.

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