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Bush E, Fielitz J, Melvin L, Martinez-Arnold M, McKinsey TA, Plichta R, Olson EN: A small molecular activator of cardiac hypertrophy uncovered in a chemical screen for modifiers of the calcineurin signaling pathway. Proc Natl Acad Sci U S A. 2004 Mar 2;101(9):2870-5. Epub 2004 Feb 19. The calcium, calmodulin-dependent phosphatase calcineurin, regulates growth and gene expression of striated muscles. The activity of calcineurin is modulated by a family of cofactors, referred to as modulatory calcineurin-interacting proteins (MCIPs). In the heart, the MCIP1 gene is activated by calcineurin and has been proposed to fulfill a negative feedback loop that restrains potentially pathological calcineurin signaling, which would otherwise lead to abnormal cardiac growth. In a high-throughput screen for small molecules capable of regulating MCIP1 expression in muscle cells, we identified a unique 4-aminopyridine derivative exhibiting an embedded partial structural motif of serotonin (5-hydroxytryptamine, 5-HT). This molecule, referred to as pyridine activator of myocyte hypertrophy, acts as a selective agonist for 5-HT (2A/2B) receptors and induces hypertrophy of cardiac muscle cells through a signaling pathway involving calcineurin and a kinase-dependent mechanism that inactivates class II histone deacetylases, which act as repressors of cardiac growth. These findings identify MCIP1 as a downstream target of 5-HT (2A/2B) receptor signaling in cardiac muscle cells and suggest possible uses for 5-HT (2A/2B) agonists and antagonists as modulators of cardiac growth and gene expression. |
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