Cardiac Purkinje cell versus ventricular myocyte gene profile

Affymetrix array gene expression analysis using RNA isolated from Purkinje cells and ventricular myocytes from the Cntn2-EGFP/ a-MHC-Cre/ floxed-tdTomato compound transgenic dual fluorescence reporter mouse Cardiac Purkinje cells are important triggers of ventricular arrhythmias associated with heritable and acquired syndromes. The mechanisms responsible for this pro-arrhythmic behavior are incompletely understood. Here, through transcriptional profiling of genetically labeled cardiomyocytes, we identified expression of Purkinje cell protein-4 (Pcp4), a putative regulator of calmodulin and Ca2+/calmodulin-dependent kinase II (CaMKII) signaling, exclusively within the His-Purkinje network. Using Pcp4-null mice and acquired cardiomyopathy models, we demonstrate that reduced expression of PCP4 is associated with CaMKII activation, abnormal electrophysiology, dysregulated intracellular calcium handling and pro-arrhythmic behavior in isolated Purkinje cells. We also show that Pcp4-null mice display profound autonomic dysregulation and arrhythmic behavior in vivo. Together, these results demonstrate that PCP4 regulates cardiac excitability through both Purkinje cell autonomous and central mechanisms and identify this modulator of CaMKII signaling as a potential arrhythmia-susceptibility candidate. Purkinje cells and ventiruclar myocytes were isolated from 4 separate hearts, yielding 4 replicates of each group.