Oberley T D, Schultz J L, Li N, Oberley L W
Department of Pathology, University of Wisconsin Medical School, Madison, USA.
Free Radic Biol Med. 1995 Jul;19(1):53-65. doi: 10.1016/0891-5849(95)00012-m.
Manganese superoxide dismutase (MnSOD) levels were monitored as a function of time in culture to determine whether these levels were altered at logarithmic growth versus when the cells exhibited density limitation of growth. For comparison, activities of the antioxidant enzymes copper, zinc superoxide dismutase (CuZnSOD), catalase, and glutathione peroxidase were also evaluated. Four cell lines were studied, two of which exhibited density limitation of growth and two of which did not. Each cell line showed a unique antioxidant enzyme profile. The two cell lines that showed density limitation of growth also demonstrated induction of MnSOD at the time when the cells stopped proliferating in culture, whereas the other two cell lines did not show induction of MnSOD. There was no strict correlation between density limitation of growth and activities of the other antioxidant enzymes. To determine whether SOD varied with various phases of the cell cycle, NIH/3T3 cells were synchronized using serum starvation, and then SOD activities were measured during quiescence (G0) and the phase of DNA synthesis (S-phase). MnSOD was decreased during S-phase compared with G0, whereas CuZnSOD was increased during S-phase compared with G0, demonstrating alteration of SOD activities with varying phases of the cell cycle. This study suggests the possibility that increased MnSOD may correlate with decreased cell proliferation and suggests significant alterations in SOD activities during the cell cycle.
监测培养过程中锰超氧化物歧化酶（MnSOD）水平随时间的变化，以确定这些水平在对数生长期与细胞表现出生长密度限制时是否发生改变。作为比较，还评估了抗氧化酶铜锌超氧化物歧化酶（CuZnSOD）、过氧化氢酶和谷胱甘肽过氧化物酶的活性。研究了四种细胞系，其中两种表现出生长密度限制，另外两种则没有。每种细胞系都显示出独特的抗氧化酶谱。表现出生长密度限制的两种细胞系在细胞在培养中停止增殖时也表现出MnSOD的诱导，而另外两种细胞系未显示出MnSOD的诱导。生长密度限制与其他抗氧化酶的活性之间没有严格的相关性。为了确定超氧化物歧化酶（SOD）是否随细胞周期的不同阶段而变化，使用血清饥饿法使NIH/3T3细胞同步化，然后在静止期（G0）和DNA合成期（S期）测量SOD活性。与G0期相比，S期MnSOD降低，而与G0期相比，S期CuZnSOD升高，表明SOD活性随细胞周期的不同阶段而改变。这项研究表明，MnSOD增加可能与细胞增殖减少相关，并表明细胞周期中SOD活性有显著变化。
