Wang J Y, McCormack S A, Johnson L R
Department of Surgery, University of Maryland Medical School, Baltimore, USA.
Am J Physiol. 1996 Feb;270(2 Pt 1):G355-62. doi: 10.1152/ajpgi.1996.270.2.G355.
The current study determines whether nonmuscle myosin II is involved in the process requiring polyamines for the stimulation of cell migration in an in vitro model that mimics the early stages of epithelial restitution. Treatment with alpha-difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase (ODC), for 4 days totally inhibited ODC activity and depleted intracellular polyamines in the IEC-6 cells. Nonmuscle myosin II concentrations in DFMO-treated cells were decreased by 75%, and stress fibers were sparse or absent. The most striking feature of DFMO-treated cells was the appearance of many small punctate foci of myosin II in the cell interior. Migration of DFMO-treated cells was reduced by 80%. In the presence of DFMO, exogenous putrescine not only returned nonmuscle myosin II levels and distribution toward normal but also restored cell migration to control levels. The administration of wortmannin, an inhibitor of myosin light chain kinase, significantly inhibited cell migration over the denuded area in control cells and in those treated with DFMO + polyamines. These results indicate that 1) polyamine depletion by DFMO is associated with decreased concentration and reorganization of nonmuscle myosin II in IEC-6 cells and 2) exogenous spermidine reverses the inhibitory effects of DFMO.
本研究在一个模拟上皮修复早期阶段的体外模型中，确定非肌肉肌球蛋白II是否参与了细胞迁移过程中多胺刺激所需的过程。用鸟氨酸脱羧酶（ODC）的特异性抑制剂α-二氟甲基鸟氨酸（DFMO）处理4天，完全抑制了IEC-6细胞中的ODC活性并耗尽了细胞内的多胺。DFMO处理的细胞中非肌肉肌球蛋白II的浓度降低了75%，应力纤维稀疏或缺失。DFMO处理的细胞最显著的特征是细胞内部出现许多小的点状肌球蛋白II病灶。DFMO处理的细胞迁移减少了80%。在DFMO存在的情况下，外源性腐胺不仅使非肌肉肌球蛋白II的水平和分布恢复正常，还将细胞迁移恢复到对照水平。肌球蛋白轻链激酶抑制剂渥曼青霉素的施用显著抑制了对照细胞以及用DFMO + 多胺处理的细胞在裸露区域的细胞迁移。这些结果表明：1）DFMO导致的多胺耗竭与IEC-6细胞中非肌肉肌球蛋白II的浓度降低和重组有关；2）外源性亚精胺可逆转DFMO的抑制作用。
