Chatterjee B, Nath T S, Roy A K
J Biol Chem. 1981 Jun 25;256(12):5939-41.
Changes in the mRNAs coding for specific hepatic proteins in male rats during aging were examined by in vitro translation of the liver mRNA in the rabbit reticulocyte lysate. Characterization of the [35S]methionine-labeled translation products by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis followed by autoradiography showed major age-dependent changes in the hepatic concentrations of three mRNA species. The translation products of these three mRNAs were found to have Mr = 28,500, 26,300, and 19,500 and are called senescence marker proteins (SMP) 1, 2, 3, respectively. On the basis of its immunochemical reactivity, SMP-3 (Mr = 19,500) is identified as alpha 2u-globulin while the mRNAs for SMP-1 (Mr = 28,500) and SMP-2 (Mr = 26,300) code for two yet uncharacterized proteins. The liver of the prepubertal male rats was found to contain the mRNA for SMP-2 and showed almost complete absence of the mRNAs for SMP-1 and SMP-3. However, the mRNAs for both SMP-1 and SMP-3 were present in the postpubertal young adults while the mRNA for SMP-2 was absent. Finally, when the animals reached senescence, the mRNAs for SMP-1 and SMP-3 disappeared from the liver with the reappearance of the SMP-2 mRNA. Age-dependent regulation of the mRNAs for these three senescence marker proteins can serve as an important model for the study of differential gene expression during aging.
通过兔网织红细胞裂解液中肝脏mRNA的体外翻译，研究了雄性大鼠衰老过程中特定肝脏蛋白编码mRNA的变化。用十二烷基硫酸钠-聚丙烯酰胺平板凝胶电泳对[35S]甲硫氨酸标记的翻译产物进行表征，随后进行放射自显影，结果显示三种mRNA的肝脏浓度存在主要的年龄依赖性变化。发现这三种mRNA的翻译产物的分子量分别为28,500、26,300和19,500，分别称为衰老标记蛋白（SMP）1、2、3。基于其免疫化学反应性，SMP-3（分子量 = 19,500）被鉴定为α2u-球蛋白，而SMP-1（分子量 = 28,500）和SMP-2（分子量 = 26,300）的mRNA编码两种尚未鉴定的蛋白质。发现青春期前雄性大鼠的肝脏含有SMP-2的mRNA，而几乎完全没有SMP-1和SMP-3的mRNA。然而，SMP-1和SMP-3的mRNA在青春期后的年轻成年大鼠中均存在，而SMP-2的mRNA则不存在。最后，当动物进入衰老期时，SMP-1和SMP-3的mRNA从肝脏中消失，而SMP-2的mRNA重新出现。这三种衰老标记蛋白mRNA的年龄依赖性调节可作为研究衰老过程中差异基因表达的重要模型。
