title: A novel protein kinase C target site in protein kinase D is phosphorylated in response to signals for cardiac hypertrophy.
abstract: Protein kinase D (PKD) regulates cardiac myocyte growth and contractility through phosphorylation of proteins such as class IIa histone deacetylases (HDACs) and troponin I (TnI). In response to agonists that activate G-protein-coupled receptors (GPCRs), PKD is phosphorylated by protein kinase C (PKC) on two serine residues (Ser-738 and Ser-742 in human PKD1) within an activation loop of the catalytic domain, resulting in stimulation of PKD activity. Here, we identify a novel PKC target site located adjacent to the auto-inhibitory pleckstrin homology (PH) domain in PKD. This site (Ser-412 in human PKD1) is conserved in each of the three PKD family members and is efficiently phosphorylated by multiple PKC isozymes in vitro. Employing a novel anti-phospho-Ser-412-specific antibody, we demonstrate that this site in PKD is rapidly phosphorylated in primary cardiac myocytes exposed to hypertrophic agonists, including norepinephrine (NE) and endothelin-1 (ET-1). Differential sensitivity of this event to pharmacological inhibitors of PKC, and data from in vitro enzymatic assays, suggest a predominant role for PKCδ in the control of PKD Ser-412 phosphorylation. Together, these data suggest a novel, signal-dependent mechanism for controlling PKD function in cardiac myocytes.
authors: Department of Biology, Gilead Sciences, Palo Alto, CA 94304, USA. dillon.phan@gilead.com
authors: Dillon
authors: D
authors: Phan
authors: Matthew S
authors: MS
authors: Stratton
authors: Q Khai
authors: QK
authors: Huynh
authors: Timothy A
authors: TA
authors: McKinsey
mesh_terms: D000595:Amino Acid Sequence; D006332:Cardiomegaly / Q000201:enzymology*; D019332:Endothelin-1 / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D008969:Molecular Sequence Data; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology; D009638:Norepinephrine / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*
chemical_list: D019332:Endothelin-1; C089212:protein kinase D; D011493:Protein Kinase C; D009638:Norepinephrine