Forced expression of the homeodomain protein Gax inhibits cardiomyocyte proliferation and perturbs heart morphogenesis

Development ◽  
1997 ◽  
Vol 124 (21) ◽  
pp. 4405-4413 ◽  
Author(s):  
S.A. Fisher ◽  
E. Siwik ◽  
D. Branellec ◽  
K. Walsh ◽  
M. Watanabe
Keyword(s):  
Cell Cycle ◽  
Heart Development ◽  
Negative Regulator ◽  
Homeodomain Protein ◽  
Cardiomyocyte Proliferation ◽  
Heart Morphogenesis ◽  
Chicken Heart ◽  
Nuclear Expression ◽  
Compact Zone ◽  
Myocyte Proliferation

The development of the tubular heart into a complex four-chambered organ requires precise temporal and region-specific regulation of cell proliferation, migration, death and differentiation. While the regulatory mechanisms in heart morphogenesis are not well understood, increasing attention has focused on the homeodomain proteins, which are generally linked to morphogenetic processes. The homeodomain containing gene Gax has been shown to be expressed in heart and smooth muscle tissues. In this study, the Gax protein was detected in the nuclei of myocardial cells relatively late in chicken heart development, at a time when myocyte proliferation is declining. To test the hypothesis that the Gax protein functions as a negative regulator of cardiomyocyte proliferation, a replication-defective adenovirus was used to force its precocious nuclear expression during chicken heart morphogenesis. In experiments in which Gax- and beta-galactosidase-expressing adenoviruses were co-injected, clonal expansion of myocytes was reduced, consistent with inhibition of myocyte proliferation. This effect on proliferation was corroborated by the finding that the percentage of exogenous Gax-expressing myocytes that were positive for the cell cycle marker PCNA decreased over time and was lower than in control myocytes. The precocious nuclear expression of Gax in tubular hearts resulted in abnormal heart morphology, including small ventricles with rounded apices, a thinned compact zone and coarse trabeculae. These results suggest a role for the Gax protein in heart morphogenesis causing proliferating cardiomyocytes to withdraw from the cell cycle, thus influencing the size and shape that the heart ultimately attains.

Abstract 8: Reprogramming of Adult Mammalian Cardiomyocytes Towards Proliferation and Regeneration Through Comparative Analyses of Epicardial and Myocardial Cells

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Guo Huang ◽  
Justin Judd ◽  
Jonathan Lovas
Keyword(s):  
Cell Cycle ◽  
Candidate Genes ◽  
Heart Development ◽  
Comparative Approach ◽  
Myocardial Cells ◽  
Cardiomyocyte Proliferation ◽  
Developmental Gene ◽  
Cardiac Muscle Cells ◽  
Comparative Analyses ◽  
Epicardial Cells

Heart development and regeneration require an elegant balance of cell proliferation and differentiation. In both adult zebrafish and neonatal mouse cardiac regeneration, new cardiomyocytes are shown to originate from pre-existing cardiomyocytes through de-differentiation of mature cells to the immature progenitor cell state, with developmental gene program reactivation and cell cycle reentry. Interestingly, after adult mammalian cardiac injury, both cardiac muscle cells and the epicardial cells that envelope the heart reinitiate developmental gene programs. However, adult epicardial cells are able to proliferate following injury but adult cardiomyocytes are not capable. We investigated the genetic circuitry of mouse epicardial cells and myocardial cells in different developmental stages and in response to injury. Such comparative analyses revealed a group of ~50 candidate genes that may be responsible for the permanent cell cycle arrest of cardiomyocytes. We generated adenoviruses that express these candidate genes individually, and demonstrated that the mixed viral pool possessed a robust activity to promote proliferation of adult mouse cardiomyocytes. Our comparative approach and functional screens may lead to identification of the dormant genetic circuitry in adult mammalian heart that can be reactivated to drive robust cardiomyocyte proliferation and regeneration.

Abstract 348: Interleukin 13 is Required for Neonatal Heart Regeneration

2017 ◽  
Vol 121 (suppl_1) ◽  
Author(s):  
Caitlin C O’Meara ◽  
Dana Murphy ◽  
Angela Lemke ◽  
Michael J Flister
Keyword(s):  
Cell Cycle ◽  
Knockout Mice ◽  
Heart Development ◽  
Contradictory Result ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Rat Cardiomyocytes ◽  
Hypertrophic Growth ◽  
Interleukin 13 ◽  
Neonatal Heart

Shortly after birth neonatal mice can fully regenerate their hearts, but this potential is lost in the first week of life. Cell cycle entry of existing cardiomyocytes is thought to be an essential mechanism enabling neonatal mouse heart regeneration. In previous studies we found that the cytokine interleukin 13 (IL13) was a an upstream regulator of differentially expressed gene networks during neonatal heart regeneration and stimulated cell cycle activity of cultured rat cardiomyocytes, suggesting that this factor might be important in neonatal heart regeneration in vivo . In the present study, we subjected wildtype and IL13 knockout mice to ventricular apical resection at one day of age and assessed heart regeneration 21 days post resection (dpr). Compared to wildtype controls, IL13 knockout mice failed to regenerate their hearts as determined by extensive scar formation at the ventricular apex. To gain insight into the mechanism of impaired regeneration, we quantified cardiomyocyte proliferation and expression of macrophage markers at 7 dpr. We found no difference in gene expression of macrophage markers in IL13 knockout mice compared to wildtype. Interestingly, IL13 knockout mice demonstrate a significant increase cardiomyocyte cell cycle activity as determined by phosphorylated Histone H3 (pH3) staining. This seemingly contradictory result appears to be due to an underlying developmental defect in IL13 knockout hearts. Cardiomyocytes in IL13 knockout mice appeared large and disorganized. Cardiomyocytes from IL13 knockout unoperated mice showed decreased pH3 staining and had increased expression marker of hypertrophic growth such as Nppb and Nppa. Histologically, hearts from IL13 knockout mice appeared to have a dilated cardiomyopathy phenotype. Collectively our data suggests that during heart development IL13 influences proliferative versus hypertrophic growth. We surmise that following neonatal apical resection in IL13 knockout mice the significant increase in cardiomyocyte proliferation is a compensatory attempt to repair the injury, but the underlying cardiomyocyte phenotype inhibits complete regeneration. These data are the first to report a role for IL13 in normal heart development and neonatal heart regeneration.

Abstract 23: Overexpression Of Tbx20 In Adult Cardiomyocytes Promotes Cardiomyocyte Proliferation And Improves Cardiac Function Post Myocardial Infarction

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Fu-li Xiang ◽  
Katherine Yutzey
Keyword(s):  
Myocardial Infarction ◽  
Cell Cycle ◽  
Cardiac Function ◽  
Heart Development ◽  
Weight Ratio ◽  
Negative Regulator ◽  
Proliferation Markers ◽  
Post Surgery ◽  
Adult Cardiomyocytes ◽  
Scar Size

Background: Adult mammalian cardiomyocytes (CM) have the potential to proliferate, but this is not sufficient to compensate for the massive loss of functional CMs after myocardial infarction (MI), which remains a leading cause of death in the US. During embryonic heart development, the transcription factor Tbx20 is required for CM proliferation, and Tbx20 overexpression promotes fetal characteristics in adult CMs when initiated before birth in mice. We hypothesize that Tbx20 overexpression (Tbx20OE), when induced in adult CMs after injury, improves cardiac function and repair via dedifferentiation of CMs, thus promoting cell cycle re-entry and repair in mice post-MI. Methods and Results: αMHCMerCreMer (STG) and the inducible cardiomyocyte-specific Tbx20 transgenic (αMHCMerCreMer/CAG-CAT-Tbx20, DTG) mice were subjected to MI or sham surgeries. Tbx20OE was induced 3 days post-surgery via tamoxifen to specifically target cardiac repair post-MI. In sham-operated mice, no difference in cardiac function or morphology was observed between DTG and STG groups. However, more proliferating CMs as labeled by Ki67 were found in DTG sham myocardium compared to STG. Expression of cyclin D1, E1 (cell cycle markers) and IGF1 mRNA was increased, while p21 (cell cycle inhibitor) and Meis1 (negative regulator of proliferation) were decreased, in DTG sham hearts compared to STG controls. In mice subjected to MI, cardiac function, as measured by echocardiography, was significantly improved, and the infarct scar size was smaller (58.1% vs 38.3%) in the DTG group compared to STG controls 2 and 4 weeks post-MI. Myocardial hypertrophy determined by heart to body weight ratio and myocyte diameter was also significantly reduced in DTG heart compared to STG 4 weeks post-MI. Thus, induction of Tbx20OE post-MI injury leads to improved cardiac performance, decreased scar size, and decreased maladaptive cardiac remodeling. Ongoing studies will determine if proliferation indices (Ki67, pHH3, aurora kinase B) and cytokinesis of CM post-MI are increased in myocardium and isolated adult cardiomyocytes with Tbx20OE. Conclusions: Tbx20OE in adult CM activates cell proliferation markers and also improves cardiac function and repair in mice when induced post-MI.

Role of GSK-3 in Cardiac Health: Focusing on Cardiac Remodeling and Heart Failure

2021 ◽  
Vol 22 ◽  
Author(s):  
Ubaid Tariq ◽  
Shravan Kumar Uppulapu ◽  
Sanjay K Banerjee
Keyword(s):  
Heart Failure ◽  
Cell Cycle ◽  
Cardiac Development ◽  
Glycogen Synthase ◽  
Cardiac Regeneration ◽  
Negative Regulator ◽  
Cell Cycle Regulators ◽  
Cardiomyocyte Proliferation ◽  
Gsk 3Β

: Glycogen synthase kinase 3 (GSK-3) is a ubiquitously expressed serine/threonine kinase and was first identified as a regulator of glycogen synthase enzyme and glucose homeostasis. It regulates cellular processes like cell proliferation, metabolism, apoptosis and development. Recent findings suggest that GSK-3 is required to maintain the normal cardiac homeostasis that regulates cardiac development, proliferation, hypertrophy and fibrosis. GSK-3 is expressed as two isoforms, α and β. Role of GSK-3α and GSK-3β in cardiac biology is well documented. Both isoforms have common as well as isoform-specific functions. Human data also suggests that GSK-3β is downregulated in hypertrophy and heart failure, and acts as a negative regulator. Pharmacological inhibition of GSK-3α and GSK-3β leads to the endogenous cardiomyocyte proliferation and cardiac regeneration by inducing the upregulation of cell cycle regulators, which results in cell cycle re-entry and DNA synthesis. It was found that cardiac specific knockout (KO) of GSK-3α retained cardiac function, inhibited cardiovascular remodelling and restricted scar expansion during ischemia. Further, knockout of GSK-3α decreases cardiomyocyte apoptosis and enhances its proliferation. However, GSK-3β KO also results in hypertrophic myopathy due to cardiomyocyte hyper-proliferation. Thus GSK-3 inhibitors are named as a double-edged sword because of their beneficial and off target effects. This review focuses on the isoform specific functions of GSK-3 that will help in better understanding about the role of GSK-3α and GSK-3β in cardiac biology and pave a way for the development of new isoform specific GSK-3 modulator for the treatment of ischemic heart disease, cardiac regeneration and heart failure.

Targeting the Cardiomyocyte Cell Cycle for Heart Regeneration

2018 ◽  
Vol 20 (2) ◽  
pp. 241-254 ◽  
Author(s):  
Paola Locatelli ◽  
Carlos Sebastián Giménez ◽  
Martín Uranga Vega ◽  
Alberto Crottogini ◽  
Mariano Nicolás Belaich
Keyword(s):  
Cell Cycle ◽  
Heart Development ◽  
Cell Cycle Regulation ◽  
Scientific Progress ◽  
Cardiomyocyte Proliferation ◽  
Daughter Cells ◽  
Regulation Mechanisms ◽  
Diverse Origin ◽  
Cycle Regulation ◽  
Regenerative Therapies

Adult mammalian cardiomyocytes (CMs) exhibit limited proliferative capacity, as cell cycle activity leads to an increase in DNA content, but mitosis and cytokinesis are infrequent. This makes the heart highly inefficient in replacing with neoformed cardiomyocytes lost contractile cells as occurs in diseases such as myocardial infarction and dilated cardiomyopathy. Regenerative therapies based on the implant of stem cells of diverse origin do not warrant engraftment and electromechanical connection of the new cells with the resident ones, a fundamental condition to restore the physiology of the cardiac syncytium. Consequently, there is a growing interest in identifying factors playing relevant roles in the regulation of the CM cell cycle to be targeted in order to induce the resident cardiomyocytes to divide into daughter cells and thus achieve myocardial regeneration with preservation of physiologic syncytial performance. Despite the scientific progress achieved over the last decades, many questions remain unanswered, including how cardiomyocyte proliferation is regulated during heart development in gestation and neonatal life. This can reveal unknown cell cycle regulation mechanisms and molecules that may be manipulated to achieve cardiac self-regeneration. We hereby revise updated data on CM cell cycle regulation, participating molecules and pathways recently linked with the cell cycle, as well as experimental therapies involving them.

scholarly journals EARLY BUD-BREAK 1 and EARLY BUD-BREAK 3 control resumption of poplar growth after winter dormancy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Abdul Azeez ◽  
Yiru Chen Zhao ◽  
Rajesh Kumar Singh ◽  
Yordan S. Yordanov ◽  
Madhumita Dash ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Molecular Mechanisms ◽  
Negative Regulator ◽  
Bud Break ◽  
Positive Regulator ◽  
Regulatory Module ◽  
Trees And Shrubs ◽  
Poplar Growth ◽  
Identification And Characterization

AbstractBud-break is an economically and environmentally important process in trees and shrubs from boreal and temperate latitudes, but its molecular mechanisms are poorly understood. Here, we show that two previously reported transcription factors, EARLY BUD BREAK 1 (EBB1) and SHORT VEGETATIVE PHASE-Like (SVL) directly interact to control bud-break. EBB1 is a positive regulator of bud-break, whereas SVL is a negative regulator of bud-break. EBB1 directly and negatively regulates SVL expression. We further report the identification and characterization of the EBB3 gene. EBB3 is a temperature-responsive, epigenetically-regulated, positive regulator of bud-break that provides a direct link to activation of the cell cycle during bud-break. EBB3 is an AP2/ERF transcription factor that positively and directly regulates CYCLIND3.1 gene. Our results reveal the architecture of a putative regulatory module that links temperature-mediated control of bud-break with activation of cell cycle.

Abstract 124: Function of the Cytoskeletal Proteins Alpha-catenins in Myocardial Growth Control

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Jifen Li ◽  
Sarah Carrante ◽  
Roslyn Yi ◽  
Frans van Roy ◽  
Glenn L. Radice
Keyword(s):  
Heart Development ◽  
Growth Control ◽  
Cytoskeletal Proteins ◽  
Neonatal Rat ◽  
Nuclear Accumulation ◽  
Mouse Heart ◽  
Cardiomyocyte Proliferation ◽  
Rat Cardiomyocytes ◽  
Neonatal Cardiomyocytes

Introduction: Mammalian heart possesses regenerative potential immediately after birth and lost by one week of age. The mechanisms that govern neonatal cardiomyocyte proliferation and regenerative capacity are poorly understood. Recent reports indicate that Yap-Tead transcriptional complex is necessary and sufficient for cardiomyocyte proliferation. During postnatal development, N-cadherin/catenin adhesion complex becomes concentrated at termini of cardiomyocytes facilitating maturation of a specialized intercellular junction structure, the intercalated disc (ICD). This process coincides with the time cardiomyocytes exit cell cycle soon after birth. Hypothesis: We hypothesize that coincident with maturation of ICD α-catenins sequester transcriptional coactivator Yap in cytosol thus preventing activation of genes critical for cardiomyocyte proliferation. Methods: We deleted αE-catenin / αT-catenin genes (α-cat DKO) in perinatal mouse heart and knockdown (KD) α-catenins in neonatal rat cardiomyocytes to study functional impact of α-catenins ablation on ICD maturation. Results: We previously demonstrated that adult α-cat DKO mice exhibited decrease in scar size and improved function post myocardial infarction. In present study, we investigated function of α-catenins during postnatal heart development. We found increase in the number of Yap-positive nuclei (58.7% in DKO vs. 35.8 % in WT, n=13, p<0.001) and PCNA (53.9% in DKO vs. 47.8%, n=8, p<0.05) at postnatal day 1 and day 7 of α-cat DKO heart, respectively. Loss of α-catenins resulted in reduction in N-cadherin at ICD at day 14. We observed an increase number of mononucleated myocytes and decrease number of binucleated myocytes in α-cat DKO compared to controls. Using siRNA KD, we were able to replicate α-cat DKO proliferative phenotype in vitro. The number of BrdU-positive cells was decreased in α-cat KD after interfering with Yap expression (2.91% in α-cat KD vs. 2.02% in α-cat/Yap KD, n>2500 cells, p<0.05), suggesting α-catenins regulate cell proliferation through Yap in neonatal cardiomyocytes. Conclusion: Our results suggest that maturation of ICD regulates α-catenin-Yap interactions in cytosol, thus preventing Yap nuclear accumulation and cardiomyocyte proliferation.

Abstract 396: Regulation of Cardiomyocyte Proliferation by the Hippo Pathway and Dystrophin Complex

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Yuka Morikawa ◽  
John Leach ◽  
Todd Heallen ◽  
Ge Tao ◽  
James F Martin
Keyword(s):  
Cell Cycle ◽  
Muscular Dystrophy ◽  
Dna Synthesis ◽  
De Novo ◽  
Hippo Pathway ◽  
Myocardial Damage ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Heart Repair ◽  
The Hippo Pathway

Regeneration in mammalian hearts is limited due to the extremely low renewal rate of cardiomyocytes and their inability to reenter the cell cycle. In rodent hearts, endogenous regenerative capacity exists during development but is rapidly repressed after birth, at which time growth is by hypertrophy. During the developmental and neonatal periods, heart regeneration occurs through proliferation of pre-existing cardiomyocytes. Our approach of activating heart regeneration is to uncover the mechanisms responsible for repression of cardiomyocyte proliferation. The Hippo pathway controls heart size by repressing cardiomyocyte proliferation during development. By deleting Salv , a modulator of the Hippo pathway, we found that myocardial damage in postnatal and adult hearts was repaired both anatomically and functionally. This heart repair occurred primary through proliferation of preexisting cardiomyocytes. During repair, cardiomyocytes reenter the cell cycle; de novo DNA synthesis, karyokinesis, and cytokinesis all take place. The dystrophin glycoprotein complex (DGC) is essential for muscle maintenance by anchoring the cytoskeleton and extracellular matrix. Disruption of the DGC results in muscular dystrophies, including Duchenne muscular dystrophy, resulting in both skeletal and cardiac myopathies. Recently the DGC was shown to regulate cardiomyocyte proliferation and we found that the DGC and the Hippo pathway components directly interact. To address if the DGC and the Hippo pathway coordinately regulate cardiomyocyte proliferation, we conditionally deleted Salv in the mouse model of muscular dystrophy, the mdx line. We found that simultaneous disruption of both the DGC and Hippo pathway leads an increased de novo DNA synthesis and cytokinesis in cardiomyocytes after heart damage. Our findings provide new insights into the mechanisms leading to heart repair through proliferation of endogenous cardiomyocytes.

Abstract 14391: Transient Cell Cycle Induction in Cardiomyocytes is a Promising Approach to Treat Ischemia Induced Heart Failure

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Riham Abouleisa ◽  
Qinghui Ou ◽  
Xian-liang Tang ◽  
Mitesh Solanki ◽  
Yiru Guo ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cardiac Function ◽  
Single Cell ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Cardiomyocyte Proliferation ◽  
Specific Expression ◽  
Control Virus

Rationale: The regenerative capacity of the heart to repair itself after myocardial infarction (MI)is limited. Our previous study showed that ectopic introduction of Cdk1/CyclinB1 andCdk4/CyclinD1 complexes (4F) promotes cardiomyocyte proliferation in vitro and in vivo andimproves cardiac function after MI. However, its clinical application is limited due to the concernsfor tumorigenic potential in other organs. Objectives: To first, identify on a single cell transcriptomic basis the necessary reprogrammingsteps that cardiomyocytes need to undertake to progress through the proliferation processfollowing 4F overexpression, and then, to determine the pre-clinical efficacy of transient andcardiomyocyte specific expression of 4F in improving cardiac function after MI in small and largeanimals. Methods and Results: Temporal bulk and single cell RNAseq of mature hiPS-CMs treated with4F or LacZ control for 24, 48, or 72 h revealed full cell cycle reprogramming in 15% of thecardiomyocyte population which was associated with sarcomere disassembly and metabolicreprogramming. Transient overexpression of 4F specifically in cardiomyocytes was achievedusing non-integrating lentivirus (NIL) driven by TNNT2 (TNNT2-4F-NIL). One week after inductionof ischemia-reperfusion injury in rats or pigs, TNNT2-4F-NIL or control virus was injectedintramyocardially. Compared with controls, rats or pigs treated with TNNT2-4F-NIL showed a 20-30% significant improvement in ejection fraction and scar size four weeks after treatment, asassessed by echocardiography and histological analysis. Quantification of cardiomyocyteproliferation in pigs using a novel cytokinesis reporter showed that ~10% of the cardiomyocyteswithin the injection site were labelled as daughter cells following injection with TNNT2-4F-NILcompared with ~0.5% background labelling in control groups. Conclusions: We provide the first understanding of the process of forced cardiomyocyteproliferation and advanced the clinical applicability of this approach through minimization ofoncogenic potential of the cell cycle factors using a novel transient and cardiomyocyte-specificviral construct.

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