Respiratory function decline and DNA mutation in mitochondria, oxidative stress and altered gene expression during aging. Chang Gung Med

Aging is a biological process that is characterized by the gradual loss of physiological function and increases in the sus-ceptibility to disease of an individual. During the aging process, a wide spectrum of alterations in mitochondria and mitochondrial DNA (mtDNA) has been observed in somatic tissues of humans and animals. This is associated with the decline in mitochondrial respiratory function; excess produc-tion of the reactive oxygen species (ROS); increase in the oxidative damage to mtDNA, lipids and proteins in mitochon-dria; accumulation of point mutations and large-scale deletions of mtDNA; and altered expression of genes involved in inter-mediary metabolism. It has been demonstrated that the ROS may cause oxidative damage and mutations of mtDNA and alterations of the expression of several clusters of genes in aging tissues and senescent cells. We found that intracellula