Quantitation of mitochondrial DNA, RNA, and protein in starved and starved‐refed rat liver

Abstract

The purpose of this study was to investigate the problem of mitochondrial biogenesis in rat liver. The approach consisted of isolating mitochondria from control, 6 day starved and 6 day starved-5 day refed rats and comparing their DNA, RNA and protein content. This was performed by isolating the mitochondria by reorienting rate zonal centrifugation in sucrose gradients. It was found that six days of starvation resulted in a loss of 30% of the body weight, 55% of the liver weight, 40% of the mitochondrial protein, 60% of the mitochondrial RNA, but only 20% of the mitrochondrial DNA. It was also shown that refeeding of the rats for five days resulted in a restoration to normal or near normal levels in all the parameters measured. Further experiments employing the incorporation of 3H-TTP into into isolated mitochondria indicated that the maintenance of mitochondrial DNA was not the result of continuous DNA sythesis.

The role of mitochondria in aging

“…Additionally, RC capacity is reduced up to 40% in rat liver mitochondria of old animals (24 months) in comparison with juvenile animals (3-4 months) (19). A similar decline of RC function has been reported in the spleen, whereas mitochondrial function in the brain was not reported to change with age in rats (19). The RC capacity has also been reported to decline with age in human liver, heart, and skeletal muscle (20,21).…”

“…The number of mitochondria decreases with age in liver cells of mice (15), rats (16), and humans (17,18), concurrent with a decrease in mtDNA copy number and mitochondrial protein levels (19). Additionally, RC capacity is reduced up to 40% in rat liver mitochondria of old animals (24 months) in comparison with juvenile animals (3-4 months) (19). A similar decline of RC function has been reported in the spleen, whereas mitochondrial function in the brain was not reported to change with age in rats (19).…”

C11orf83, a Mitochondrial Cardiolipin-Binding Protein Involved in bc1 Complex Assembly and Supercomplex Stabilization

“…Since the remodelling of the cristae seems to be a prerequisite to apoptosis (71), we suspect that this may also be a consequence of the IM destabilization. Finally, since crista alteration and reduced RC activity were reported to occur in aged cells (42)(43)(44)(45)(46)72), we suspect that mitochondrial dysfunctions observed in C11orf83-depleted cells could explain their growth deficit after several passages.…”

“…Since C11orf83 was shown to be mitochondrial and several studies proposed a connection between aging and mitochondria dysfunctions (42)(43)(44)(45)(46), a deeper analysis of the impact of C11orf83 depletion on mitochondrial physiology was performed. To comply with the instructions of the American Type Culture Collection (ATCC) (47), which recommend the use of cell lines within five passages to ensure reliable and reproducible results, all the following experiments were performed with freshly thawed cells.…”

Blue Journal Conference. Aging and Susceptibility to Lung Disease

“…Changes in mitochondrial function have been implicated in regulating the life span of model organisms (14). Aging is associated with a decline in the number of mitochondria, mitochondrial DNA copy number, and mitochondrial protein levels in rodents and humans (67)(68)(69)(70)(71). This may lead to a loss of mitochondrial capacity and place a metabolic limit on cellular function, resulting in increased susceptibility to catastrophic metabolic failure in response to genomic and proteomic stress, thereby contributing to lung frailty during aging.…”