Partial replacement of cardiac troponin I with a non-phosphorylatable mutant at serines 43/45 attenuates the contractile dysfunction associated with PKCepsilon phosphorylation

J Mol Cell Cardiol. 2006 Apr;40(4):465-73. doi: 10.1016/j.yjmcc.2005.12.009. Epub 2006 Jan 30.


We have previously reported a transgenic mouse that over-expresses constitutively active PKCepsilon in the myocardium and exhibits a steady progression to heart failure. Associated with the decline in function was an increased phosphorylation of sarcomeric proteins including cardiac troponin I (cTnI). To determine whether PKCepsilon phosphorylation of cTnI is sufficient to induce cardiac maladaptation, we have generated a double transgenic mouse (DbTG) that expresses constitutively active PKCepsilon and cTnI harboring non-phosphorylatable mutations in the putative PKC phosphorylation sites (S43A, S45A). We compared the hemodynamic and biochemical properties of the hearts from the DbTG mice to the non-transgenic and single transgenic lines at both 3 and 12 months of age. While no significant differences in LV function were noted in 3-month groups, the depression of function in the PKCepsilon mice was attenuated in the double transgenic mice at 12 months. The improvement in cardiac function was correlated with decreased beta-myosin heavy chain and ANF mRNA expression in the 12m DbTG mice. The extent of cTnI phosphorylation was determined using a novel one-dimensional, non-equilibrium isoelectric focusing technique. At 3 months the migration of cTnI phospho-species was different in the PKCepsilon mice and to a lesser degree in the DbTG compared to all other groups. At 12 months additional phospho-species were observed in both the PKCepsilon and DbTG samples, along with an overall shift in the distribution of phospho-species in all groups due to age. These results suggest that phosphorylation of cTnI by PKCepsilon is associated with contractile dysfunction and partial replacement of serines 43/45 improves cardiac performance. Therefore, we conclude that phosphorylation of cTnI at Ser 43 and 45 may contribute to the progression of failure.

Publication types

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

MeSH terms

  • Aging / genetics
  • Aging / metabolism
  • Amino Acid Substitution*
  • Animals
  • Cell Line
  • Heart Failure / genetics
  • Heart Failure / metabolism
  • Mice
  • Mice, Transgenic
  • Myocardial Contraction* / genetics
  • Myocardium / metabolism*
  • Myocardium / pathology
  • Phosphorylation
  • Protein Kinase C-epsilon / metabolism*
  • Protein Processing, Post-Translational* / genetics
  • Troponin I / genetics
  • Troponin I / metabolism*
  • Ventricular Function, Left / genetics


  • Troponin I
  • Protein Kinase C-epsilon