Proteome changes in CaMKIIδ_C-overexpressing cardiac myocytes

Abstract 

Recent studies have demonstrated that the expression as well as the activity of Ca/calmodulin-dependent protein kinase IIδ_C (CaMKIIδ_C) is increased in heart failure. Transgenic overexpression of CaMKIIδ_C in mouse hearts results in severe dilated cardiomyopathy. So far, little is known about CaMKIIδ_C-induced changes in gene expression and proteome alteration. We hypothesize that proteome changes similar to those found in advanced heart failure can be assessed even after short term overexpression of CaMKIIδ_C in an in vitro culture model. Thus, we designed a study using a proteomic approach combined with adenovirus-mediated gene transfer of CaMKIIδ_C to identify early CaMKIIδ_C-induced changes in cardiac myocyte phenotype on proteome level. CaMKIIδ_C was overexpressed by adenovirus-mediated gene transfer in isolated cardiac myocytes of adult rabbits for 48 h. Proteome changes were analyzed by two-dimensional gel electrophoresis and mass spectrometry (MS). Overexpression of CaMKIIδ_C resulted in a decreased expression of 21 proteins (at least twofold change of expression, P<.05, n=10). Using in-gel digest and MS, we identified 13 out of these 21 proteins. CaMKIIδ_C overexpression leads to a reduced abundance of NADH dehydrogenase, lactate dehydrogenase, pyruvate kinase, dihydrolipoamide succinyltransferase, creatine kinase M, heat shock protein 70, elongation factor Tu, and superoxide dismutase. The profile of the proteome changes induced by CaMKIIδ_C overexpression after 48 h displayed striking alterations of metabolic proteins, cell-protecting proteins including antioxidants, and proteins involved in protein synthesis. Interestingly, the observed proteome changes are in common with the phenotype of failing cardiac myocytes on the protein level. These altered proteins may act individually as contributors to heart failure, which is observed after overexpression of CaMKIIδ_C in genetically altered mice.

Keywords: Proteomics, Cardiac metabolism, CaMKII, Heart failure