Inhibition of Calcineurin-NFAT Hypertrophy Signaling by cGMP-Dependent Protein Kinase Type I in Cardiac Myocytes

• Published in: Proceedings of the National Academy of Sciences - PNAS 2002-08, Vol.99 (17), p.11363-11368
• Main Authors: Fiedler, Beate, Lohmann, Suzanne M., Smolenski, Albert, Linnemüller, Stephan, Pieske, Burkert, Schröder, Frank, Molkentin, Jeffery D., Drexler, Helmut, Wollert, Kai C.
• Format: Article
• Language: English
• Subjects: Adenoviruses; Animals; Animals, Newborn; Biological Sciences; Calcineurin - physiology; Calcineurin Inhibitors; Calcium Channels, L-Type - physiology; Calcium Signaling - physiology; Cardiomegaly - enzymology; Cardiomegaly - physiopathology; Cardiomegaly - prevention & control; Cardiovascular disease; Cells; Cells, Cultured; Cyclic GMP - analogs & derivatives; Cyclic GMP - pharmacology; Cyclic GMP-Dependent Protein Kinase Type I; Cyclic GMP-Dependent Protein Kinases - antagonists & inhibitors; Cyclic GMP-Dependent Protein Kinases - metabolism; DNA-Binding Proteins - antagonists & inhibitors; DNA-Binding Proteins - physiology; Enzyme Activation; Genes; Heart - physiology; Heart Ventricles; Hypertrophy; Ion Channel Gating - physiology; Luciferases - genetics; Luciferases - metabolism; Messenger RNA; Myocardium - metabolism; Natriuretic Peptide, Brain - genetics; NFATC Transcription Factors; Nitric oxide; Nuclear Proteins; P values; Phosphatases; Plasmids; Probability; Promoter Regions, Genetic; Proteins; Rats; Rats, Sprague-Dawley; Signal Transduction - physiology; Thionucleotides - pharmacology; Transcription factors; Transcription Factors - antagonists & inhibitors; Transcription Factors - physiology; Transcription, Genetic; Transfection; Virions; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.162100799

Recent investigation has focused on identifying signaling pathways that inhibit cardiac hypertrophy, a major risk factor for cardiovascular morbidity and mortality. In this context, nitric oxide (NO), signaling via cGMP and cGMP-dependent protein kinase type I(PKG I), has been recognized as a negative regulator of cardiac myocyte (CM) hypertrophy. However, the underlying mechanisms are poorly understood. Here, we show that PKG I inhibits CM hypertrophy by targeting the calcineurin-NFAT signaling pathway. Calcineurin, a Ca2+-dependent phosphatase, promotes hypertrophy in part by activating NFAT transcription factors which induce expression of hypertrophic genes, including brain natriuretic peptide (BNP). Activation of PKG I by NO/cGMP in CM suppressed NFAT transcriptional activity, BNP induction, and cell enlargement in response to α1-adrenoreceptor stimulation but not in response to adenoviral expression of a Ca2+-independent, constitutively active calcineurin mutant, thus demonstrating NO-cGMP-PKG I inhibition of calcineurin-NFAT signaling upstream of calcineurin. PKG I suppressed single L-type Ca2+-channel open probability, [Ca2+]itransient amplitude, and, most importantly, L-type Ca2+-channel current-induced NFAT activation, indicating that PKG I targets Ca2+-dependent steps upstream of calcineurin. Adenoviral expression of PKG I enhanced NO/cGMP inhibitory effects upstream of calcineurin, confirming that PKG I mediates NO/cGMP inhibition of calcineurin-NFAT signaling. In CM overexpressing PKG I, NO/cGMP also suppressed BNP induction and cell enlargement but not NFAT activation elicited by constitutively active calcineurin, which is consistent with additional, NFAT-independent inhibitory effect(s) of PKG I downstream of calcineurin. Inhibition of calcineurin-NFAT signaling by PKG I provides a framework for understanding how NO inhibits cardiac myocyte hypertrophy.