Presenting Author John A. Burns School of Medicine Honolulu, Hawaii
Introduction: Pyruvate kinase (PKM1) directs pyruvate to the Krebs cycle for oxidative metabolism in the healthy heart. Our lab described a hypoxia-mediated switch to the alternatively spliced isoform PKM2, enhancing pyruvate to lactate conversion. Recently, we have also found that Pkm2 knockout (KO) mice had profound depletion of basal glucose in the heart compared to control mice. Pkm2 has also been shown to reduce oxidative damage and promote cardiomyocyte cell proliferation after myocardial infarction (MI). We hypothesize that upregulation of PKM2 can alter metabolic pathways by promoting glycolysis, and that after injury, this can preserve ATP production, protecting the heart from the stresses of hypoxia and injury.
Methods: Global Pkm2 KO mice were subjected to permanent ligation of the left anterior descending coronary artery to mimic an MI. RNA-seq analysis of left ventricles from control (n=8) and Pkm2 KO mice (n=8) before and 3 days after sham or MI surgery was performed. Semi-quantitative real-time PCR was used to confirm changes in selected genes of interest.
Results: Loss of Pkm2 moderately altered gene expression at baseline (qlt;0.05, FDRlt;0.05). Notably, the mitochondrial gene COX3 was downregulated in Pkm2 KO hearts. 68 genes were differentially expressed in Pkm2 KO hearts after MI, not observed in control MI hearts. MI of Pkm2 KO hearts resulted in considerable reduction of transcripts of enzymes in the insulin signaling pathway, mitochondrial oxidative phosphorylation, mitochondrial uncoupling, fatty acid metabolism, and increase in transcripts encoding enzymes in the pentose phosphate pathway, response to oxidative stress, and apoptotic signaling. Semi-quantitative PCR of selected genes involved in glucose metabolism confirmed RNA-seq results.
Conclusions: RNA-seq analysis of Pkm2 KO hearts demonstrated that loss of Pkm2 altered gene expression of metabolic and mitochondrial enzymes. Pkm2 KO hearts also showed increased abundance of pro-apoptotic markers which may be a result of increased oxidative stress.
Support or Funding Information
This work was supported by the NIH [P30 GM103341 to RVS; T32 HL115505 to KCL; P30 CA071789 and 5G12 MD00760 to Microscopy and Imaging Core] and NCI [P30 CA071789 to Genomics and Bioinformatics Shared Resource].
This work was supported by the NIH [P30 GM103341 to RVS; T32 HL115505 to KCL; P30 CA071789 and 5G12 MD00760 to Microscopy and Imaging Core] and NCI [P30 CA071789 to Genomics and Bioinformatics Shared Resource].
