PITX2C Transcriptionally Regulates Metabolic Gene Expression

Atrial fibrillation affects approximately 1-2% of the Canadian population and has been strongly associated with SNPs near the PITX2 locus on chromosome 4q25.1,2 PITX2C encodes a transcription factor known for regulating left-right asymmetry within neonatal heart development.3 During the first week of postnatal development, a metabolic switch from glycolysis to fatty acid oxidation occurs leading to changes in cardiomyocyte proliferation and binucleation. 4 We hypothesize that the loss of PITX2C impairs neonatal rat atrial cardiomyocyte (NRAM) maturation by disrupting the expression of metabolic genes during the neonatal period. To test this, we transfected NRAMs with 100 nm of a control siRNA or a siRNA targeted to knockdown Pitx2c (548 siRNA). 48-hours later, these cells where either stained for immunofluorescence or sent for RNA sequencing. NRAM maturation was assessed using a phospho-histone H3 (pH3) antibody, DAPI and cTnT, then analyzed for proliferation and binucleation in knockdowns compared to controls. Metabolic gene expression was assessed through RNA sequencing and analyzed using Ingenuity Pathway Analysis. Our results demonstrate that the loss of PITX2C does not significantly alter proliferation or binucleation in NRAMs at postnatal day 2, however does impact regulation of metabolic and biosynthetic pathway genes.