Disruption of protein kinase A localization using a trans-activator of transcription (TAT)-conjugated A-kinase-anchoring peptide reduces cardiac function

J Biol Chem. 2010 Sep 3;285(36):27632-40. doi: 10.1074/jbc.M110.146589. Epub 2010 Jun 26.


Localization of protein kinase A (PKA) via A-kinase-anchoring proteins (AKAPs) is important for cAMP responsiveness in many cellular systems, and evidence suggests that AKAPs play an important role in cardiac signaling. To test the importance of AKAP-mediated targeting of PKA on cardiac function, we designed a cell-permeable peptide, which we termed trans-activator of transcription (TAT)-AKAD for TAT-conjugated A-kinase-anchoring disruptor, using the PKA binding region of AKAP10 and tested the effects of this peptide in isolated cardiac myocytes and in Langendorff-perfused mouse hearts. We initially validated TAT-AKAD as a PKA localization inhibitor in cardiac myocytes by the use of confocal microscopy and cellular fractionation to show that treatment with the peptide disrupts type I and type II PKA regulatory subunits. Knockdown of PKA activity was demonstrated by decrease in phosphorylation of phospholamban and troponin I after beta-adrenergic stimulation in isolated myocytes. Treatment with TAT-AKAD reduced myocyte shortening and rates of contraction and relaxation. Injection of TAT-AKAD (1 microM), but not scrambled control peptide, into the coronary circulation of isolated perfused hearts rapidly (<1 min) and reversibly decreased heart rate and peak left ventricular developed pressure. TAT-AKAD also had a pronounced effect on developed pressure (-dP/dt), consistent with a delayed relaxation of the heart. The effects of TAT-AKAD on heart rate and contractility persisted in hearts pretreated with isoproterenol. Disruption of PKA localization with TAT-AKAD thus had negative effects on chronotropy, inotropy, and lusitropy, thereby indicating a key role for AKAP-targeted PKA in control of heart rate and contractile function.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • A Kinase Anchor Proteins / metabolism*
  • Adrenergic beta-Agonists / pharmacology
  • Amino Acid Sequence
  • Animals
  • Binding, Competitive
  • Cattle
  • Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit / metabolism
  • Cyclic AMP-Dependent Protein Kinase RIalpha Subunit / metabolism
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • Heart / drug effects*
  • Heart / physiology*
  • Heart Rate / drug effects
  • Male
  • Mice
  • Molecular Sequence Data
  • Muscle Cells / cytology
  • Muscle Cells / metabolism
  • Myocardial Contraction / drug effects
  • Peptides / chemistry
  • Peptides / metabolism*
  • Peptides / pharmacology*
  • Perfusion
  • Permeability
  • Phosphorylation / drug effects
  • Protein Kinase Inhibitors / pharmacology
  • Protein Transport / drug effects
  • Rats
  • Transcriptional Activation / drug effects*


  • A Kinase Anchor Proteins
  • Adrenergic beta-Agonists
  • Cyclic AMP-Dependent Protein Kinase RIIbeta Subunit
  • Cyclic AMP-Dependent Protein Kinase RIalpha Subunit
  • Peptides
  • Protein Kinase Inhibitors
  • Cyclic AMP-Dependent Protein Kinases