UCP2 and dilated cardiomyopathy: Puzzled by our initial observation of decreased mean and maximal lifespan in DM mice, we proceeded to look more closely into changes caused by UCP2 depletion in heart, as this was the tissue with the strongest upregulation of UCP2 levels (Figure 1D) and dilated cardiomyopathy was recognized as one of the most prominent changes in mtDNA mutator mice [2].