Calcineurin-NFAT signaling regulates the cardiac hypertrophic response in coordination with the MAPKs.
Prolonged cardiac hypertrophy of pathologic etiology is associated with arrhythmia, sudden death, decompensation, and dilated cardiomyopathy. In an attempt to understand the mechanisms that underlie the hypertrophic response, extensive investigation has centered on a characterization of the molecular pathways that initiate or maintain the pathologic growth of individual cardiac myocytes. While a large number of signal transduction cascades have been identified as critical regulators of cardiac hypertrophy, here the scientific evidence implicating the protein phosphatase calcineurin (PP2B) and the mitogen-activated protein kinases (MAPK) as co-regulators of reactive hypertrophy will be discussed. Gain- and loss-of-function studies in genetically altered mice and in cultured cardiomyocytes have demonstrated the necessity and sufficiency of calcineurin to regulate pathologic cardiac hypertrophy. However, using similar approaches, the hypertrophic regulatory role attributed to various branches of the MAPK signaling pathway has been less conclusive, although a loose consensus suggests that the c-Jun N-terminal kinases (JNK) and p38 kinases function as mediators of dilated cardiomyopathy, while extracellular signal-regulated kinases (ERKs) function as regulators of hypertrophy. More recently, the actions of calcineurin and MAPK signaling pathways have been shown to be co-dependent such that unitary activation of calcineurin in myocytes leads to up-regulation in ERK and JNK signaling, but down-regulation in p38 signaling. Conversely, unitary activation of JNK or p38 in cardiac myocytes leads to down-regulation of calcineurin effectiveness by directly antagonizing nuclear factor of activated T cells (NFAT) nuclear occupancy. Thus, an emerging paradigm suggests that calcineurin-NFAT and MAPK signaling pathways are inter-dependent and together orchestrate the cardiac hypertrophic response.
Molkentin
Jeffery D
JD
Division of Molecular Cardiovascular Biology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA. jeff.molkentin@cchmc.org
D000818:Animals; D019703:Calcineurin / Q000378:metabolism*; D002311:Cardiomyopathy, Dilated / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
D004268:DNA-Binding Proteins; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D014157:Transcription Factors; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D019703:Calcineurin