Mechanisms of Signal Transduction
Protein Kinase D Links Gq-coupled Receptors to cAMP Response Element-binding Protein (CREB)-Ser133 Phosphorylation in the Heart*

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Many growth regulatory stimuli promote cAMP response element-binding protein (CREB) Ser133 phosphorylation, but the physiologically relevant CREB-Ser133 kinase(s) in the heart remains uncertain. This study identifies a novel role for protein kinase D (PKD) as an in vivo cardiac CREB-Ser133 kinase. We show that thrombin activates a PKCδ-PKD pathway leading to CREB-Ser133 phosphorylation in cardiomyocytes and cardiac fibroblasts. α1-Adrenergic receptors also activate a PKCδ-PKD-CREB-Ser133 phosphorylation pathway in cardiomyocytes. Of note, while the epidermal growth factor (EGF) promotes CREB-Ser133 phosphorylation via an ERK-RSK pathway in cardiac fibroblasts, the thrombin-dependent EGFR transactivation pathway leading to ERK-RSK activation does not lead to CREB-Ser133 phosphorylation in this cell type. Adenoviral-mediated overexpression of PKCδ (but not PKCϵ or PKCα) activates PKD; PKCδ and PKD1-S744E/S748E overexpression both promote CREB-Ser133 phosphorylation. Pasteuralla multocida toxin (PMT), a direct Gαq agonist that induces robust cardiomyocyte hypertrophy, also activates the PKD-CREB-Ser133 phosphorylation pathway, leading to the accumulation of active PKD and Ser133-phosphorylated CREB in the nucleus, activation of a CRE-responsive promoter, and increased Bcl-2 (CREB target gene) expression in cardiomyocyte cultures. Cardiac-specific Gαq overexpression also leads to an increase in PKD-Ser744/Ser748 and CREB-Ser133 phosphorylation as well as increased Bcl-2 protein expression in the hearts of transgenic mice. Collectively, these studies identify a novel Gαq-PKCδ-PKD-CREB-Ser133 phosphorylation pathway that is predicted to contribute to cardiac remodeling and could be targeted for therapeutic advantage in the setting of heart failure phenotypes.

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This work was supported, in whole or in part, by National Institutes of Health Grants HL77860, HL-67101, and HL-28958. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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These authors contributed equally to this study.