Lepidi H, Benoliel A M, Mege J L, Bongrand P, Capo C
Laboratoire d'Immunologie, Hôpital de Sainte-Marguerite, Marseille, France.
J Cell Sci. 1992 Sep;103 ( Pt 1):145-56. doi: 10.1242/jcs.103.1.145.
Uniform concentrations of chemoattractants such as formylpeptides induced a morphological polarization of human polymorphonuclear leucocytes (PMNs) and a concentration of F-actin at the cell front. They also induced a transient increase in filamentous actin (F-actin) which preceded the cell shape change. We combined fluorescence microscopy and image analysis to study the localization of F-actin, as revealed by a specific probe (bodipyTM phallacidin) in suspended PMNs stimulated by chemoattractants. F-actin exhibited remarkable concentration in focal points after a 30 s exposure to 10(-8) M formylmethionyl-leucyl-phenylalanine (fMet-Leu-Phe), although no shape change of PMNs was detectable. A 10-min incubation with formylpeptide (10(-6) to 10(-9) M) induced the morphological polarization of PMNs and the appearance of a principal focus of F-actin in the cell head region and a secondary focus in the cell posterior end. The distribution of F-actin-associated fluorescence in 2D images of polarized PMNs might be due to an actual concentration of F-actin in privileged areas, to a local concentration of plasma membrane drawing filamentous actin or to variations in the cell volume. Then, we studied the distribution of a cytoplasmic marker, fluorescein diacetate and a membrane probe, TMA-DPH, in unstimulated rounded PMNs and in spherical and morphologically polarized PMNs stimulated by formylpeptide. The distribution of neither of these probes was correlated with F-actin distribution, especially in rounded PMNs stimulated 30 s with 10(-8) M fMet-Leu-Phe, suggesting that F-actin was concentrated in two foci located in the cell head region and in the cell posterior end. In addition, zymosan-activated serum induced the morphological polarization of PMNs and the appearance of two foci of filamentous actin, demonstrating that binding of formylpeptide to its specific receptor was not required for F-actin reorganization. We conclude that the accumulation of F-actin probably resulted from local filament assembly and put forward the hypothesis that microfilament reorganization in two centres drives the morphological polarization of PMNs.
诸如甲酰肽等趋化因子的均匀浓度可诱导人多形核白细胞（PMN）发生形态极化，并使F-肌动蛋白在细胞前端聚集。它们还会在细胞形状改变之前诱导丝状肌动蛋白（F-肌动蛋白）短暂增加。我们结合荧光显微镜和图像分析技术，研究了趋化因子刺激下悬浮PMN中由特异性探针（bodipyTM鬼笔环肽）显示的F-肌动蛋白的定位。在暴露于10(-8) M甲酰甲硫氨酰-亮氨酰-苯丙氨酸（fMet-Leu-Phe）30秒后，F-肌动蛋白在焦点处显著聚集，尽管此时未检测到PMN的形状变化。用甲酰肽（10(-6)至10(-9) M）孵育10分钟可诱导PMN发生形态极化，并在细胞头部区域出现F-肌动蛋白的主要聚集点，在细胞后端出现次要聚集点。极化PMN的二维图像中F-肌动蛋白相关荧光的分布可能是由于F-肌动蛋白在特定区域的实际聚集、质膜局部聚集吸引丝状肌动蛋白或细胞体积的变化。然后，我们研究了细胞质标记物荧光素二乙酸酯和膜探针TMA-DPH在未刺激的圆形PMN以及由甲酰肽刺激的球形和形态极化PMN中的分布。这些探针的分布均与F-肌动蛋白的分布无关，尤其是在用10(-8) M fMet-Leu-Phe刺激30秒的圆形PMN中，这表明F-肌动蛋白集中在位于细胞头部区域和细胞后端的两个聚集点。此外，酵母聚糖激活的血清可诱导PMN发生形态极化，并出现两个丝状肌动蛋白聚集点，表明F-肌动蛋白重组并不需要甲酰肽与其特异性受体结合。我们得出结论，F-肌动蛋白的积累可能是由于局部细丝组装导致的，并提出了微丝在两个中心重组驱动PMN形态极化的假说。
