255 Zac1, jointly down-regulated by preconditioning and postconditioning in a mouse model of myocardial ischemia/reperfusion: a transcriptomic approach

Abstract

Ischemic preconditioning and postconditioning are two effective therapeutic strategies for reducing infarct size in animal models and humans. The aim of our study was to compare the early regulated genes of preconditioning and postconditioning using a transcriptomic approach. C57Bl6, Zac1+/– KO (n=7) and WT littermates (n=4) mice underwent an IR (40 min. ischemia/60 min.reperfusion) protocol. C57Bl6 mice were randomly assigned to different groups: IR (n=22); postconditioning (PostC, n=21): a protocol of 3 cycles of 1-minute reperfusion and 1-minute reocclusion was applied at the onset of reperfusion; preconditioning (PreC, n=15; same algorithm but applied before ischemia. At the end of surgery, left ventricles were assigned to RNA extraction or infarct size assessment. Homemade mouse oligo microarrays were used for gene expression profiling (Montpellier GenomiX Facilities). Determination of area at risk (AR) and infarct size was assessed by TTC staining and planimetry. Our study revealed that despite a similar cardioprotection offered by PreC and PostC on infarct size, PostC regulates a larger number of genes compared to PreC (242 versus 40). Only 8 genes were jointly regulated by PreC and PostC and considered as putative cardioprotective key regulators. Among these candidates, Zac1 was down regulated at the transcriptional levels upon PreC and PostC. Moreover, infarct size/AR was 29%-decreased in Zac1 +/– KO mice subjected to a surgical protocol of myocardial IR. Using pangenomic microarrays, we identified and compared the gene profiles of preconditioning and postconditioning versus IR in the mouse left ventricle in vivo. Among the genes jointly downregulated by preconditioning and postconditioning, Zac1 was identified as a putative cardioprotective key regulator. Indeed downregulation at the transcriptional and protein levels of Zac1 leads to cardioprotection against IR.