Alpha1-adrenergic receptors activate AKT via a Pyk2/PDK-1 pathway that is tonically inhibited by novel protein kinase C isoforms in cardiomyocytes

Circ Res. 2006 Dec 8;99(12):1367-75. doi: 10.1161/01.RES.0000252830.01581.fd. Epub 2006 Nov 16.

Abstract

AKT is a potent antiapoptotic kinase, but its role in the cardioprotective actions of alpha(1)-adrenergic receptors (ARs) remains uncertain, because alpha(1)-ARs typically induce little-to-no AKT activation in most cardiomyocyte models. This study identifies a prominent alpha(1)-AR-dependent AKT activation pathway that is under tonic inhibitory control by novel protein kinase Cs (nPKCs) in neonatal rat cardiomyocyte cultures. We also implicate Pyk2, Pyk2 complex formation with PDK-1 and paxillin, and increased PDK-1-Y373/376 phosphorylation as the mechanism that links alpha(1)-AR activation to increased AKT phosphorylation. nPKCs (which are prominent alpha(1)-AR effectors) interfere with this alpha(1)-AR-dependent AKT activation by blocking Pyk2/PDK-1/paxillin complex formation and PDK-1-Y373/376 phosphorylation. Additional studies used an adenoviral-mediated overexpression strategy to show that Pyk2 exerts dual controls on antiapoptotic PDK-1/AKT and proapoptotic c-Jun N-terminal kinase (JNK) pathways. Although the high nPKC activity of most cardiomyocyte models favors Pyk2 signaling to JNK (and cardiac apoptosis), the cardioprotective actions of Pyk2 through the PDK-1/AKT pathway are exposed when PKC or JNK activation is prevented. Collectively, these studies identify JNK and AKT as functionally distinct downstream components of the alpha(1)-AR/Pyk2 signaling pathway. We also implicate nPKCs as molecular switches that control the balance of signaling via proapoptotic JNK and antiapoptotic PDK-1/AKT pathways, exposing a novel mechanism for nPKC-dependent regulation of cardiac hypertrophy and failure.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Apoptosis / physiology
  • Cardiomegaly / metabolism
  • Cardiomegaly / pathology
  • Cells, Cultured
  • Enzyme Inhibitors / pharmacology
  • Focal Adhesion Kinase 2 / genetics
  • Focal Adhesion Kinase 2 / metabolism*
  • Gene Expression
  • Heart Failure / metabolism
  • Heart Failure / pathology
  • Heart Ventricles / cytology
  • Indoles / pharmacology
  • Isoenzymes / antagonists & inhibitors
  • Isoenzymes / metabolism
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Maleimides / pharmacology
  • Myocytes, Cardiac / cytology
  • Myocytes, Cardiac / metabolism*
  • Paxillin / metabolism
  • Phosphorylation
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / metabolism
  • Protein Kinases / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Rats
  • Receptors, Adrenergic, alpha-1 / metabolism*
  • Signal Transduction / physiology

Substances

  • Enzyme Inhibitors
  • Indoles
  • Isoenzymes
  • Maleimides
  • Paxillin
  • Pxn protein, rat
  • Receptors, Adrenergic, alpha-1
  • Protein Kinases
  • protein kinase D
  • Focal Adhesion Kinase 2
  • Proto-Oncogene Proteins c-akt
  • Protein Kinase C
  • JNK Mitogen-Activated Protein Kinases
  • bisindolylmaleimide I