Simchowitz L, Cragoe E J
Department of Medicine, Veterans Administration Medical Center, St. Louis, Missouri.
J Biol Chem. 1990 Aug 15;265(23):13457-63.
The effect of a series of di- and trivalent cations on the locomotor response of human neutrophils to the chemotactic tripeptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) was investigated. Migration was assessed by the leading front method. The cations inhibited FMLP-stimulated chemotaxis in the rank order: Ni2+ approximately Co2+ greater than Sr2+ greater than Zn2+ greater than Mn2+ approximately La3+ greater than Cd2+ approximately Ba2+ much greater than Mg2+. Benzamil, which blocks Na+/Ca2+ exchange, did not alter chemotaxis by itself but prevented the suppressive effects of each of the polyvalent cations on motility. The ion selectivity sequence and the lack of activity of benzamil are strikingly different than for O(-2) generation, thereby implying different modes of action in the two functional expressions. The F-actin content of the cells was monitored by the fluorescence of rhodamine-phalloidin. Each of the cations displayed comparable efficacy in blocking the polymerization of actin in FMLP-activated cells. Likewise, benzamil exhibited a protective effect, completely overcoming the inhibitory action of the polyvalent cations. The results indicate that these foreign ions gain access to the cell interior via a benzamil-sensitive pathway, namely Na+/Ca2+ exchange. Upon entry into the cytosol, they then interfere with the formation of filaments from actin monomers. These studies help to shed light on the interaction of divalent cations with cytoskeletal and contractile elements in cell motility.
研究了一系列二价和三价阳离子对人中性粒细胞向趋化三肽N-甲酰-甲硫氨酰-亮氨酰-苯丙氨酸（FMLP）的运动反应的影响。通过前沿法评估迁移情况。这些阳离子对FMLP刺激的趋化作用的抑制顺序为：Ni2+≈Co2+＞Sr2+＞Zn2+＞Mn2+≈La3+＞Cd2+≈Ba2+＞＞Mg2+。阻断Na+/Ca2+交换的苄amil本身并不改变趋化作用，但可防止每种多价阳离子对运动性的抑制作用。离子选择性序列和苄amil的无活性与O(-2)生成的情况显著不同，这意味着在这两种功能表达中存在不同的作用模式。通过罗丹明-鬼笔环肽的荧光监测细胞的F-肌动蛋白含量。每种阳离子在阻断FMLP激活的细胞中肌动蛋白的聚合方面表现出相当的效力。同样，苄amil也表现出保护作用，完全克服了多价阳离子的抑制作用。结果表明，这些外来离子通过苄amil敏感途径，即Na+/Ca2+交换进入细胞内部。进入胞质溶胶后，它们随后干扰肌动蛋白单体形成细丝。这些研究有助于阐明二价阳离子在细胞运动中与细胞骨架和收缩元件的相互作用。
