Zhizhina G P, Korobko V G, Alesenko A V
Biokhimiia. 1994 Nov;59(11):1756-65.
The tumour necrosis factor alpha (TNF-alpha) initiates DNA degradation in many types of cells, eventually resulting in a programmed cell death (apoptosis). In order to study the mechanism of TNF-alpha action in vivo, the dynamics of mouse liver DNA fragmentation was examined after intraperitoneal administration of recombinant hTNF-alpha (10 and 40 micrograms per animal). The number of single-strand (SSB) and double-strand (DSB) breaks was determined electrophoretically and interruption of hydrogen bonds (secondary structure defects SSD) were studied by the kinetic formaldehyde method. In parallel experiments the accumulation of peroxide products in DNA, the activity of sphingomyelinase and the content of sphingosine in liver cell nuclei were measured. Sphingomyelinase activation and sphingosine accumulation in the nuclei were found to coincide in time with the maximal values of DNA degradation parameters (SSB, DBS and SSD). TNF-alpha caused a dose-dependent accumulation in DNA peroxide products which seem to lead to the DNA damages. The role of sphingomyelin cycle products and peroxidation in DNA fragmentation induced by TNF-alpha in vivo is discussed.
肿瘤坏死因子α（TNF-α）可引发多种类型细胞中的DNA降解，最终导致程序性细胞死亡（凋亡）。为了研究TNF-α在体内的作用机制，在腹腔注射重组人TNF-α（每只动物10微克和40微克）后，检测了小鼠肝脏DNA片段化的动态变化。通过电泳法测定单链（SSB）和双链（DSB）断裂的数量，并采用动力学甲醛法研究氢键的中断（二级结构缺陷SSD）。在平行实验中，测定了DNA中过氧化物产物的积累、鞘磷脂酶的活性以及肝细胞核中鞘氨醇的含量。发现细胞核中鞘磷脂酶的激活和鞘氨醇的积累与DNA降解参数（SSB、DBS和SSD）的最大值在时间上一致。TNF-α导致DNA过氧化物产物呈剂量依赖性积累，这似乎会导致DNA损伤。本文讨论了鞘磷脂循环产物和过氧化作用在TNF-α体内诱导的DNA片段化中的作用。
