Wielckens K, George E, Pless T, Hilz H
J Biol Chem. 1983 Apr 10;258(7):4098-104.
Incubation of Ehrlich ascites tumor cells in their own ascites fluid induced a reversible metabolic adaptation to these "starvation" conditions which was associated with a fragmentation of DNA. Endogenous poly(ADP-ribose) residues also increased, reaching within 1-3 h values 6-10 times higher than in cells taken directly from the mouse peritoneum. The NAD content changed only slightly while dimethyl sulfate-induced accumulation of poly(ADP-ribose) (10-fold within 30 min) was associated with a rapid depletion of NAD (85% lost at 30 min). Nevertheless, turnover of poly(ADP-ribose) as measured by the decay rate of the polymer upon addition of benzamide was dramatically stimulated in both situations, reaching apparently identical half-lives (t 1/2 approximately equal to 1 min) in "starved" and in alkylated cells. However, since penetration of benzamide into the nucleus may be the rate-limiting factor in these studies, turnover of poly(ADP-ribose) in dimethyl sulfate-treated cells may still be much higher than that in "starved" cells. In cells treated with dimethyl sulfate, suppression of poly(ADP-ribose) synthesis by benzamide did not interfere with DNA fragmentation or with DNA resealing as determined by the nucleoid procedure. By contrast, starvation induced a type of DNA incision that was prevented by benzamide. It is proposed that starvation-induced scission of DNA occurs at specific ("regulatory?") sites requiring poly(ADP-ribose) formation to take place, while fragmentation of DNA at random as seen with alkylating agents is associated with, but not dependent on, increased poly(ADP-ribosyl)ation.
艾氏腹水瘤细胞在其自身腹水中孵育会诱导出对这些“饥饿”条件的可逆代谢适应，这与DNA片段化有关。内源性聚（ADP - 核糖）残基也会增加，在1 - 3小时内达到的值比直接从小鼠腹膜中取出的细胞高出6 - 10倍。NAD含量仅略有变化，而硫酸二甲酯诱导的聚（ADP - 核糖）积累（30分钟内增加10倍）与NAD的快速消耗有关（30分钟时损失85%）。然而，在这两种情况下，通过添加苯甲酰胺后聚合物的衰减率测量的聚（ADP - 核糖）周转率都受到显著刺激，在“饥饿”细胞和烷基化细胞中达到明显相同的半衰期（t1/2约等于1分钟）。然而，由于苯甲酰胺进入细胞核可能是这些研究中的限速因素，硫酸二甲酯处理细胞中的聚（ADP - 核糖）周转率可能仍然比“饥饿”细胞中的高得多。在用硫酸二甲酯处理的细胞中，苯甲酰胺对聚（ADP - 核糖）合成的抑制并不干扰通过核小体程序测定的DNA片段化或DNA重新封闭。相比之下，饥饿诱导了一种可被苯甲酰胺阻止的DNA切口类型。有人提出，饥饿诱导的DNA断裂发生在特定的（“调节性的？”）位点，这些位点需要聚（ADP - 核糖）形成才能发生，而烷基化剂导致的随机DNA片段化与聚（ADP - 核糖）化增加有关，但不依赖于它。
