Laitinen J, Stenius K, Eloranta T O, Hölttä E
Department of Pathology, Haartman Institute, University of Helsinki, Finland.
J Cell Biochem. 1998 Feb 1;68(2):200-12. doi: 10.1002/(sici)1097-4644(19980201)68:2<200::aid-jcb7>3.0.co;2-z.
Several studies suggest that polyamines may stabilize chromatin and play a role in its structural alterations. In line with this idea, we found here by chromatin precipitation and micrococcal nuclease (MNase) digestion analyses, that spermidine and spermine stabilize or condense the nucleosomal organization of chromatin in vitro. We then investigated the possible physiological role of polyamines in the nucleosomal organization of chromatin during the cell cycle in Chinese hamster ovary (CHO) cells deficient in ornithine decarboxylase (ODC) activity. An extended polyamine deprivation (for 4 days) was found to arrest 70% of the odc- cells in S phase. MNase digestion analyses revealed that these cells have a highly loosened and destabilized nucleosomal organization. However, no marked difference in the chromatin structure was detected between the control and polyamine-depleted cells following the synchronization of the cells at the S-phase. We also show in synchronized cells that polyamine deprivation retards the traverse of the cells through the S phase already in the first cell cycle. Depletion of polyamines had no significant effect on the nucleosomal organization of chromatin in G1-early S. The polyamine-deprived cells were also capable of condensing the nucleosomal organization of chromatin in the S/G2 phase of the cell cycle. These data indicate that polyamines do not regulate the chromatin condensation state during the cell cycle, although they might have some stabilizing effect on the chromatin structure. Polyamines may, however, play an important role in the control of S-phase progression.
多项研究表明，多胺可能使染色质稳定，并在其结构改变中发挥作用。与此观点一致，我们通过染色质沉淀和微球菌核酸酶（MNase）消化分析发现，亚精胺和精胺在体外可稳定或凝聚染色质的核小体结构。然后，我们研究了多胺在中国仓鼠卵巢（CHO）细胞鸟氨酸脱羧酶（ODC）活性缺陷的细胞周期中，对染色质核小体结构可能的生理作用。发现延长多胺剥夺时间（4天）会使70%的odc-细胞停滞在S期。MNase消化分析表明，这些细胞的核小体结构高度松散且不稳定。然而，在将细胞同步于S期后，对照细胞和多胺缺乏细胞之间未检测到染色质结构的显著差异。我们还在同步化细胞中表明，多胺剥夺在第一个细胞周期就已经延缓了细胞通过S期的进程。多胺的缺失对G1期早期至S期染色质的核小体结构没有显著影响。多胺缺乏的细胞在细胞周期的S/G2期也能够凝聚染色质的核小体结构。这些数据表明，多胺在细胞周期中并不调节染色质的凝聚状态，尽管它们可能对染色质结构有一定的稳定作用。然而，多胺可能在S期进程的控制中发挥重要作用。
