Howard T H, Oresajo C O
J Cell Biol. 1985 Sep;101(3):1078-85. doi: 10.1083/jcb.101.3.1078.
Formyl-met-leu-phe (fMLP) induces actin assembly in neutrophils; the resultant increase in F-actin content correlates with an increase in the rate of cellular locomotion at fMLP concentrations less than or equal to 10(-8) M (Howard, T.H., and W.H. Meyer, 1984, J. Cell Biol., 98:1265-1271). We studied the time course of change in F-actin content, F-actin distribution, and cell shape after fMLP stimulation. F-actin content was quantified by fluorescence activated cell sorter analysis of nitrobenzoxadiazole-phallacidin-stained cells (Howard, T.H., 1982, J. Cell Biol., 95(2, Pt. 2:327a). F-actin distribution and cell shape were determined by analysis of fluorescence photomicrographs of nitrobenzoxadiazole-phallacidin-stained cells. After fMLP stimulation at 25 degrees C, there is a rapid actin polymerization that is maximal (up to 2.0 times the control level) at 45 s; subsequently, the F-actin depolymerizes to an intermediate F-actin content 5-10 min after stimulation. The depolymerization of F-actin reflects a true decrease in F-actin content since the quantity of probe extractable from cells also decreases between 45 s and 10 min. The rate of actin polymerization (3.8 +/- 0.3-4.4 +/- 0.6% increase in F-actin/s) is the same for 10(-10) - 10(-6) M fMLP and the polymerization is inhibited by cytochalasin D. The initial rate of F-actin depolymerization (6.0 +/- 1.0-30 +/- 5% decrease in F-actin/min) is inversely proportional to fMLP dose. The F-actin content of stimulated cells at 45 s and 10 min is greater than control levels and varies directly with fMLP dose. F-actin distribution and cell shape also vary as a function of time after stimulation. 45 s after stimulation the cells are rounded and F-actin is diffusely distributed; 10 min after stimulation the cell is polarized and F-actin is focally distributed. These results indicate that actin polymerization and depolymerization follow fMLP stimulation in sequence, the rate of depolymerization and the maximum and steady state F-actin content but not the rate of polymerization are fMLP dose dependent, and concurrent with F-actin depolymerization, F-actin is redistributed and the cell changes shape.
甲酰甲硫氨酸-亮氨酸-苯丙氨酸（fMLP）可诱导中性粒细胞中的肌动蛋白组装；在fMLP浓度小于或等于10^(-8) M时，F-肌动蛋白含量的增加与细胞运动速率的增加相关（霍华德，T.H.，和W.H.迈耶，1984年，《细胞生物学杂志》，98:1265 - 1271）。我们研究了fMLP刺激后F-肌动蛋白含量、F-肌动蛋白分布和细胞形状的变化时间进程。通过对硝基苯并恶二唑-鬼笔环肽染色细胞进行荧光激活细胞分选分析来定量F-肌动蛋白含量（霍华德，T.H.，1982年，《细胞生物学杂志》，95(2, Pt. 2:327a）。通过分析硝基苯并恶二唑-鬼笔环肽染色细胞的荧光显微照片来确定F-肌动蛋白分布和细胞形状。在25℃下用fMLP刺激后，肌动蛋白迅速聚合，在45秒时达到最大值（高达对照水平的2.0倍）；随后，F-肌动蛋白在刺激后5 - 10分钟解聚至中间F-肌动蛋白含量。F-肌动蛋白的解聚反映了F-肌动蛋白含量的真正减少，因为在45秒至10分钟之间从细胞中可提取的探针量也减少了。对于10^(-10) - 10^(-6) M的fMLP，肌动蛋白聚合速率（F-肌动蛋白每秒增加3.8 +/- 0.3 - 4.4 +/- 0.6%）相同，并且聚合受到细胞松弛素D的抑制。F-肌动蛋白解聚的初始速率（F-肌动蛋白每分钟减少6.0 +/- 1.0 - 30 +/- 5%）与fMLP剂量成反比。刺激后45秒和10分钟时受刺激细胞的F-肌动蛋白含量高于对照水平，并且与fMLP剂量直接相关。F-肌动蛋白分布和细胞形状也随刺激后的时间而变化。刺激后45秒细胞变圆，F-肌动蛋白呈弥散分布；刺激后10分钟细胞极化，F-肌动蛋白呈局部分布。这些结果表明，fMLP刺激后肌动蛋白聚合和解聚按顺序发生，解聚速率、最大和稳态F-肌动蛋白含量而非聚合速率是fMLP剂量依赖性的，并且与F-肌动蛋白解聚同时发生的是，F-肌动蛋白重新分布且细胞形状改变。
