title: Epigenetic modification at Notch responsive promoters blunts efficacy of inducing notch pathway reactivation after myocardial infarction.
abstract: BACKGROUND
  The Notch pathway plays a key role in stimulating mammalian cardiomyocyte proliferation during development and in the early postnatal life; in adult zebrafish, reactivation of this pathway is also essential to drive cardiac regeneration after injury.
  
  
  OBJECTIVE
  We wanted to assess efficacy of Notch pathway stimulation in neonatal and adult hearts as a means to induce cardiac regeneration after myocardial infarction in mice.
  
  
  RESULTS
  In early postnatal life, cardiomyocyte exit from the cell cycle was paralleled by decreased Notch signaling and the establishment of a repressive chromatin environment at Notch-responsive genes, characterized by recruitment of the polycomb group enhancer of zeste homolog 2 methyltransferase and the acquisition of the histone 3 Lysine 27 trimethylation histone mark, as detected by chromatin immunoprecipitation. Forced Notch pathway activation by adenoassociated virus gene transfer of activated Notch1 or its ligand Jagged1 expanded the proliferative capacity of neonatal cardiomyocytes; this correlated with increased transcription of Notch target genes and maintenance of an open chromatin conformation at their promoters. The same adenoassociated virus vectors, however, were largely ineffective in stimulating cardiac repair after myocardial infarction in adult mice, despite optimal and long-lasting transgene expression. Analysis of Notch-responsive promoters in adult cardiomyocytes showed marks of repressed chromatin and irreversible CpG DNA methylation. Induction of adult cardiomyocyte re-entry into the cell cycle with microRNAs was independent from Notch pathway reactivation.
  
  
  CONCLUSIONS
  Notch pathway activation is crucial in regulating cardiomyocyte proliferation during the early postnatal life, but it is largely ineffective in driving cardiac regeneration in adults, because of permanent epigenetic modification at Notch-responsive promoters.
authors.affiliation: From the Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy (G.F., C.C., M.L., V.M., M.D.F., L.Z., S.Z., M.G.); and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy (C.C., M.D.F., M.G.); and Center for Translational Cardiology, Azienda Ospedaliero-Universitaria "Ospedali Riuniti di Trieste", Trieste, Italy (C.C., M.D.F., M.G.).
authors.forename: Giulia
authors.initials: G
authors.lastname: Felician
authors.affiliation: From the Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy (G.F., C.C., M.L., V.M., M.D.F., L.Z., S.Z., M.G.); and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy (C.C., M.D.F., M.G.); and Center for Translational Cardiology, Azienda Ospedaliero-Universitaria "Ospedali Riuniti di Trieste", Trieste, Italy (C.C., M.D.F., M.G.). giacca@icgeb.org collesi@icgeb.org.
authors.forename: Chiara
authors.initials: C
authors.lastname: Collesi
authors.affiliation: From the Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy (G.F., C.C., M.L., V.M., M.D.F., L.Z., S.Z., M.G.); and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy (C.C., M.D.F., M.G.); and Center for Translational Cardiology, Azienda Ospedaliero-Universitaria "Ospedali Riuniti di Trieste", Trieste, Italy (C.C., M.D.F., M.G.).
authors.forename: Marina
authors.initials: M
authors.lastname: Lusic
authors.affiliation: From the Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy (G.F., C.C., M.L., V.M., M.D.F., L.Z., S.Z., M.G.); and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy (C.C., M.D.F., M.G.); and Center for Translational Cardiology, Azienda Ospedaliero-Universitaria "Ospedali Riuniti di Trieste", Trieste, Italy (C.C., M.D.F., M.G.).
authors.forename: Valentina
authors.initials: V
authors.lastname: Martinelli
authors.affiliation: From the Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy (G.F., C.C., M.L., V.M., M.D.F., L.Z., S.Z., M.G.); and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy (C.C., M.D.F., M.G.); and Center for Translational Cardiology, Azienda Ospedaliero-Universitaria "Ospedali Riuniti di Trieste", Trieste, Italy (C.C., M.D.F., M.G.).
authors.forename: Matteo Dal
authors.initials: MD
authors.lastname: Ferro
authors.affiliation: From the Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy (G.F., C.C., M.L., V.M., M.D.F., L.Z., S.Z., M.G.); and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy (C.C., M.D.F., M.G.); and Center for Translational Cardiology, Azienda Ospedaliero-Universitaria "Ospedali Riuniti di Trieste", Trieste, Italy (C.C., M.D.F., M.G.).
authors.forename: Lorena
authors.initials: L
authors.lastname: Zentilin
authors.affiliation: From the Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy (G.F., C.C., M.L., V.M., M.D.F., L.Z., S.Z., M.G.); and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy (C.C., M.D.F., M.G.); and Center for Translational Cardiology, Azienda Ospedaliero-Universitaria "Ospedali Riuniti di Trieste", Trieste, Italy (C.C., M.D.F., M.G.).
authors.forename: Serena
authors.initials: S
authors.lastname: Zacchigna
authors.affiliation: From the Molecular Medicine Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy (G.F., C.C., M.L., V.M., M.D.F., L.Z., S.Z., M.G.); and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy (C.C., M.D.F., M.G.); and Center for Translational Cardiology, Azienda Ospedaliero-Universitaria "Ospedali Riuniti di Trieste", Trieste, Italy (C.C., M.D.F., M.G.). giacca@icgeb.org collesi@icgeb.org.
authors.forename: Mauro
authors.initials: M
authors.lastname: Giacca
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D000071221:Enhancer of Zeste Homolog 2 Protein; D044127:Epigenesis, Genetic; D006657:Histones / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D000072100:Jagged-1 Protein; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009203:Myocardial Infarction / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000502:physiology; D063151:Polycomb Repressive Complex 2 / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D051381:Rats; D017208:Rats, Wistar; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D012038:Regeneration; D000072099:Serrate-Jagged Proteins; D014158:Transcription, Genetic; D029961:Zebrafish Proteins
chemical_list: D002135:Calcium-Binding Proteins; D002843:Chromatin; D006657:Histones; D036341:Intercellular Signaling Peptides and Proteins; C000606274:Jag1 protein, mouse; C000606275:Jag1 protein, rat; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; C497763:Notch1 protein, rat; D051881:Receptor, Notch1; D000072099:Serrate-Jagged Proteins; D029961:Zebrafish Proteins; C000606276:jag1a protein, zebrafish; C578253:EZH2 protein, rat; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2
keywords: DNA methylation; chromatin; dependovirus; developmental biology; myocardial infarction