Identification of potential target genes of cardioprotection against ischemia-reperfusion injury by express sequence tags analysis in rat hearts.

Background: Ischemic preconditioning (IPC) is a powerful mechanism for limiting myocardial infarction during or after ischemia-reperfusion (IR) injury. However, effective target genes and proteins for IPC are unknown. We characterized global changes in gene expression in the heart during IR, and identified effective target genes for IPC.

Methods: Hearts were isolated from Sprague-Dawley rats under control, IR, and IPC conditions. We generated expressed-sequence-tags (ESTs) for each group and investigated their functions and the major biological processes in which they are involved using the eukaryotic clusters of orthologous groups (KOG) database and bioinformatics analysis tools.

Results: IR modified the expression of 126 genes. Of these, 62 were upregulated, 64 were downregulated, and 77 were found to be effective target genes for IPC. In KOG analysis, most of the genes whose expression was modified were involved in energy production and conversion and the cytoskeleton. A gene-to-gene interaction map revealed that IR modified the expression of genes in four major functional modules: electron transport chain/oxidative phosphorylation; tricarboxylic acid cycle/glucose metabolism/amino acid metabolism; cellular structure and contraction; and gene transcription, translation, and protein folding. At the individual gene level, the genes encoding mitochondrial cytochrome c oxidase subunits 2 and 3 were downregulated, and those encoding the major cytoskeleton components tropomyosin, myosin light chain, myomesin 2, and myosin regulatory light chain 2, as well as the gene encoding the iron-storage protein ferritin, were upregulated, and thus were identified as potential target genes. Real time PCR evaluated expression patterns of three mitochondrial IPC effective genes. Two-dimensional electrophoresis proteomic analyses revealed altered expression of 14 target proteins. The expression patterns of six proteins matched the corresponding EST expression patterns.

Conclusion: The global profiling of cardiac ischemia-related genes provides the possible mechanisms of IR and IPC and ways of treating IR injury.