Over-expression of Senescence Marker Protein-30 decreases reactive oxygen species in human hepatic carcinoma Hep G2 cells.
Senescence Marker Protein-30 (SMP30) is an androgen-independent factor that decreases with aging. We recently characterized SMP30 as a gluconolactonase (GNL) involved in the biosynthetic pathway of vitamin C and established that SMP30 knockout mice could not synthesize vitamin C in vivo. Although mice normally synthesize vitamin C, humans are prevented from doing so by mutations that have altered the gluconolactone oxidase gene during evolution. Even the SMP30/GNL present abundantly in the human liver does not synthesize vitamin C in vivo. To clarify the functions of this SMP30/GNL, we transfected the human SMP30/GNL gene into the human liver carcinoma cell line, Hep G2. The resulting Hep G2/SMP30 cells expressed approximately 10.9-fold more SMP30/GNL than Hep G2/pcDNA3 mock-transfected control cells. Examination of SMP30/GNL's impact on the state of oxidative stress in these cells revealed that formation of the reactive oxygen species (ROS) of mitochondrial and post-mitochondrial fractions from Hep G2/SMP30 cells decreased by a significant 24.0% and 18.1%, respectively, compared to those from Hep G2/pcDNA3 cells. Lipid peroxidation levels in Hep G2/SMP30 cells similarly decreased. Moreover, levels of the antioxidants superoxide dismutase (SOD) and glutathione (GSH) in Hep G2/SMP30 cells were a significant 42.6% and 62.4% lower than those in Hep G2/pcDNA3 cells, respectively. Thus, over-expression of SMP30/GNL in Hep G2 cells contributed to a decrease of ROS formation accompanied by decreases of lipid peroxidation, SOD activity and GSH levels.
Handa
Setsuko
S
Aging Regulation, Tokyo Metropolitan Institute of Gerontology, Japan.
Maruyama
Naoki
N
Ishigami
Akihito
A
D000375:Aging / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000096:biosynthesis; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D015870:Gene Expression; D005978:Glutathione / Q000378:metabolism; D056945:Hep G2 Cells / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D015227:Lipid Peroxidation; D008099:Liver / Q000201:enzymology*; D008113:Liver Neoplasms / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D014162:Transfection
D000975:Antioxidants; D002135:Calcium-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D017382:Reactive Oxygen Species; C513324:Rgn protein, mouse; D013482:Superoxide Dismutase; D002265:Carboxylic Ester Hydrolases; C020579:gluconolactonase; D005978:Glutathione; D001205:Ascorbic Acid