title: Protein kinase D isoforms are activated in an agonist-specific manner in cardiomyocytes.
abstract: Protein kinase D (PKD) exists as a family of structurally related enzymes that are activated through similar phosphorylation-dependent mechanisms involving protein kinase C (PKC). While individual PKD isoforms could in theory mediate distinct biological functions, previous studies identify a high level of functional redundancy for PKD1 and PKD2 in various cellular contexts. This study shows that PKD1 and PKD2 are activated in a stimulus-specific manner in neonatal cardiomyocytes. The α(1)-adrenergic receptor agonist norepinephrine selectively activates PKD1, thrombin and PDGF selectively activate PKD2, and endothelin-1 and PMA activate both PKD1 and PKD2. PKC activity is implicated in the α(1)-adrenergic receptor pathway that activates PKD1 and the thrombin- and PDGF-dependent pathways that activate PKD2. Endothelin-1 activates PKD via both rapid PKC-dependent and more sustained PKC-independent mechanisms. The functional consequences of PKD activation were assessed by tracking phosphorylation of CREB and cardiac troponin I (cTnI), two physiologically relevant PKD substrates in cardiomyocytes. We show that overexpression of an activated PKD1-S744E/S748E transgene increases CREB-Ser(133) and cTnI-Ser(23)/Ser(24) phosphorylation, but agonist-dependent pathways that activate native PKD1 or PKD2 selectively increase CREB-Ser(133) phosphorylation; there is no associated increase in cTnI-Ser(23)/Ser(24) phosphorylation. Gene silencing studies provide unanticipated evidence that PKD1 down-regulation leads to a compensatory increase in PKD2 activity and that down-regulation of PKD1 (alone or in combination with PKD2) leads to an increase in CREB-Ser(133) phosphorylation. Collectively, these studies identify distinct roles for native PKD1 and PKD2 enzymes in stress-dependent pathways that influence cardiac remodeling and the progression of heart failure.
authors.affiliation: Department of Pharmacology, Columbia University, New York, New York 10032, USA.
authors.forename: Jianfen
authors.initials: J
authors.lastname: Guo
authors.forename: Zoya
authors.initials: Z
authors.lastname: Gertsberg
authors.forename: Nazira
authors.initials: N
authors.lastname: Ozgen
authors.forename: Abdelkarim
authors.initials: A
authors.lastname: Sabri
authors.forename: Susan F
authors.initials: SF
authors.lastname: Steinberg
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D019943:Amino Acid Substitution; D000818:Animals; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000235:genetics; D006333:Heart Failure / Q000201:enzymology / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D032383:Myocytes, Cardiac / Q000201:enzymology* / Q000473:pathology; D009638:Norepinephrine / Q000494:pharmacology*; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000316:Adrenergic alpha-Agonists; D007527:Isoenzymes; D009124:Muscle Proteins; C089212:protein kinase D; D011493:Protein Kinase C; D009638:Norepinephrine