Pieri C, Recchioni R, Moroni F, Marcheselli F, Lipponi G
Gerontological Research Department, I.N.R.C.A., Ancona, Italy.
Mech Ageing Dev. 1992 Jun;64(1-2):177-87. doi: 10.1016/0047-6374(92)90105-m.
Three parameters which signal different stages of cell activation were analyzed in lymphocytes from young and old subjects. Merocyanine 540 (MC-540) incorporation into the membrane lipid phase was used as a very early marker of activation and was measured after 1 h of phytohemagglutinin (PHA) stimulation. The proteins coded by c-myc and c-myb protooncogenes were determined by appropriate antibodies and were taken as markers of the G0/G1 and G1/S phase transition, respectively. The number of cells which increased the uptake of MC-540 following PHA stimulation did not differ when comparing young and old individuals. Both the number of the responding cells and the size of the response were decreased during aging when the presence of the c-myc protein was taken into account. A consistent decrease of the percentage of lymphocytes able to express the c-myb protein was observed in the cells from old donors as compared to those from the young ones, but the amount of detectable protein per cell remained unchanged. Our data suggest that the deficiency of responsiveness which accompanies aging is due to impairments at different points of the cell cycle. The very low number of cells expressing the c-myb protein is likely the result of step by step elimination of those cells not able to fulfill the requirements to progress along the cell cycle.
对年轻和老年受试者淋巴细胞中标志细胞激活不同阶段的三个参数进行了分析。将部花青540（MC - 540）掺入膜脂相作为激活的极早期标志物，并在植物血凝素（PHA）刺激1小时后进行测量。通过适当抗体测定由c - myc和c - myb原癌基因编码的蛋白质，并分别将其作为G0/G1和G1/S期转变的标志物。比较年轻和老年个体时，PHA刺激后MC - 540摄取增加的细胞数量没有差异。当考虑c - myc蛋白的存在时，衰老过程中反应细胞的数量和反应大小均下降。与年轻供体的细胞相比，在老年供体的细胞中观察到能够表达c - myb蛋白的淋巴细胞百分比持续下降，但每个细胞中可检测到的蛋白量保持不变。我们的数据表明，衰老伴随的反应性缺陷是由于细胞周期不同点的损伤所致。表达c - myb蛋白的细胞数量极低可能是逐步消除那些无法满足沿细胞周期进展要求的细胞的结果。
