title: Requirement of nuclear factor of activated T-cells in calcineurin-mediated cardiomyocyte hypertrophy.
abstract: The calcium-activated phosphatase calcineurin has been implicated as a critical intracellular signal transducer of cardiomyocyte hypertrophy. Although previous data suggested the nuclear factor of activated T-cells (NFAT) as its sole transcriptional effector, the absolute requirement of NFAT as a mediator of calcineurin signaling has not been examined in the heart. We therefore investigated the expression and activation profile of NFAT genes in the heart. Four members (NFATc1-c4) are expressed in cardiomyocytes, elicit nuclear translocation upon calcineurin activation, and are able to drive transactivation of cardiac promoter luciferase constructs. To define the necessary function of NFAT factors as hypertrophic transducers, a dominant negative NFAT construct was created, encompassing part of the N-terminal region of NFATc4 containing a conserved calcineurin-binding motif. Cotransfection of this construct dose-dependently abrogated promoter activation, irrespective of the NFAT isoform used, whereas a control construct with the calcineurin-binding motif mutated displayed no such effects. Adenoviral gene transfer of dominant negative NFAT rendered cardiomyocytes resistant toward all aspects of calcineurin or agonist-induced cardiomyocyte hypertrophy, whereas adenoviral gene transfer of the control construct had no discernable effect on these parameters. These results indicate that multiple NFAT isoforms are expressed in cardiomyocytes where they function as necessary transducers of calcineurin in facilitating cardiomyocyte hypertrophy.
authors.affiliation: Department of Cardiology, Cardiovascular Research Institute Maastricht, University Hospital, P. Debyelaan 25, the Netherlands.
authors.forename: Eva
authors.initials: E
authors.lastname: van Rooij
authors.forename: Pieter A
authors.initials: PA
authors.lastname: Doevendans
authors.forename: Chiel C
authors.initials: CC
authors.lastname: de Theije
authors.forename: Fawzi A
authors.initials: FA
authors.lastname: Babiker
authors.forename: Jeffery D
authors.initials: JD
authors.lastname: Molkentin
authors.forename: Leon J
authors.initials: LJ
authors.lastname: de Windt
mesh_terms: D000818:Animals; D001483:Base Sequence; D019703:Calcineurin / Q000502:physiology*; D006332:Cardiomegaly / Q000503:physiopathology*; D002467:Cell Nucleus / Q000378:metabolism; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D050991:GATA4 Transcription Factor; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology; D051379:Mice; D050778:NFATC Transcription Factors; D020097:Natriuretic Peptide, Brain / Q000235:genetics; D009687:Nuclear Proteins; D020033:Protein Isoforms / Q000502:physiology; D021381:Protein Transport; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; D050778:NFATC Transcription Factors; C494005:Nfatc1 protein, mouse; C494009:Nfatc3 protein, mouse; D009687:Nuclear Proteins; D020033:Protein Isoforms; D014157:Transcription Factors; D020097:Natriuretic Peptide, Brain; D019703:Calcineurin