Isolation of mitochondria from liver and extraction of total RNA and protein: analyses of microRNA and protein expressions.

Several studies have indicated the presence of microRNAs (miRNAs) within mitochondria, although the origin, as well as the biological function of these mitochondrially located miRNAs is largely unknown. The identification and significance of this subcellular localization is gaining increasing relevance to the pathogenesis of certain disease states. Here we describe the isolation of highly purified mitochondria from rat liver by differential centrifugation, followed by RNAse A treatment to eliminate contaminating RNA. The coupled extraction of total RNA and protein is a more efficient design for allowing the downstream evaluation of miRNA and protein expression in mitochondria.