The hypoxic conditions induced by reduced blood flow decreases
oxygen availability in target tissues. Cellular hypoxia leads to
mitochondrial dysfunction, decreased energy production, and increased production of
reactive oxygen species. To determine the alteration in expression of mitochondrial genes after
hypoxia in cardiomyocytes, we developed a rodent mitochondrial gene chip (RoMitoChip). The chip had 1088 probe sets including 46 probe sets representing 37 mouse
mitochondrial DNA transcripts and the remaining probe sets representing mouse nuclear genes contributing to the mitochondrial structure and function. Mouse cardiomyocytes isolated from neonatal C57BL/6 mice that were subjected to
hypoxia (1%
oxygen) for different time intervals demonstrated a dichotomy in the expression profile of
tRNA and
mRNA transcripts. We report a total of 483 signature genes that were altered by
hypoxia in the cardiac myocytes and related to mitochondrial structure and function. This includes 23 transcripts on
mitochondrial DNA. Pathway analysis demonstrated predominant changes in the expression of genes involved in oxidative phosphorylation,
glucose and
fatty acid metabolism, and apoptosis. The most upregulated genes after 24 h of
hypoxia included
hypoxia-inducible factor 1, alpha subunit, inducible genes Bnip3, Pdk1, and Aldoc. Whereas Bnip3 is important in the cardiomyocyte death pathway, Pdk1
enzyme is critical in conserving mitochondrial function by diverting metabolic intermediates to glycolysis. This study identifies the participation of two important pathways, cell death and glycolytic, and two key
proteins, Bnip3 and Pdk1, playing critical roles in these pathways in cardiomyocytes after severe
hypoxia.