Allen R G, Keogh B P, Gerhard G S, Pignolo R, Horton J, Cristofalo V J
Center for Gerontological Research, Medical College of Pennsylvania, Philadelphia 19129, USA.
J Cell Physiol. 1995 Dec;165(3):576-87. doi: 10.1002/jcp.1041650316.
We have determined the activities, protein, and mRNA abundances as well as the level of transcriptional activation of two intracellular forms of the free radical metabolizing enzyme superoxide dismutase in 29 human skin fibroblast lines established from donors of different ages. SOD-1 (a copper and zinc containing form of SOD) and SOD-2 (a manganese containing form of the enzyme) activities were both observed to be significantly lower in cell lines derived from fetal skin than in lines established from postnatal skin (ages 17-94 years). The percent of total activity contributed by SOD-1 decreased in an age-associated manner from approximately 50% in the fetal lines to less than 20% in lines established from old tissue donors. All of the cell lines were screened to exclude the possibility that they contained a polymorphism known to influence SOD-2 activity. Northern blot analysis revealed three SOD-1 mRNA transcripts that were 0.5, 0.7, and 1.9 kb in length. Although SOD-1 protein abundance was lower in fetal lines than in lines derived from postnatal donors, SOD-1 mRNA abundance did not differ between fetal cells and cell lines derived from young donors. SOD-2 protein abundance and mRNA abundance were both significantly lower in fetal lines than in postnatal lines. No postnatal age-dependent differences were observed in any of the SOD-2 parameters examined. Nuclear run-on analysis revealed that fetal cell lines exhibited a lower level of transcriptional initiation for SOD-1 than postnatal lines. The transcription of SOD-2 was readily detected in postnatal lines, but undetectable in fetal lines. These results are consistent with multiple levels of control for SOD-1 expression and with a strong transcriptional influence on SOD-2 expression.
我们已经测定了29种源自不同年龄供体的人皮肤成纤维细胞系中自由基代谢酶超氧化物歧化酶两种细胞内形式的活性、蛋白质和mRNA丰度，以及转录激活水平。观察到，与源自出生后皮肤（年龄17 - 94岁）的细胞系相比，源自胎儿皮肤的细胞系中，SOD - 1（一种含铜和锌的SOD形式）和SOD - 2（一种含锰的酶形式）的活性均显著降低。SOD - 1对总活性的贡献百分比随年龄增长而降低，从胎儿细胞系中的约50%降至源自老年组织供体的细胞系中的不到20%。对所有细胞系进行了筛选，以排除它们含有已知会影响SOD - 2活性的多态性的可能性。Northern印迹分析显示有三种长度分别为0.5、0.7和1.9 kb的SOD - 1 mRNA转录本。虽然胎儿细胞系中的SOD - 1蛋白质丰度低于出生后供体来源的细胞系，但胎儿细胞与年轻供体来源的细胞系之间的SOD - 1 mRNA丰度并无差异。胎儿细胞系中的SOD - 2蛋白质丰度和mRNA丰度均显著低于出生后细胞系。在所检测的任何SOD - 2参数中，均未观察到出生后年龄依赖性差异。核转录分析显示，胎儿细胞系中SOD - 1的转录起始水平低于出生后细胞系。在出生后细胞系中很容易检测到SOD - 2的转录，但在胎儿细胞系中未检测到。这些结果与SOD - 1表达的多层次调控以及对SOD - 2表达的强烈转录影响相一致。
