Sheikh S, Gratzer W B, Pinder J C, Nash G B
Department of Physiology, The Medical School, The University of Birmingham, United Kingdom.
Biochem Biophys Res Commun. 1997 Sep 29;238(3):910-5. doi: 10.1006/bbrc.1997.7407.
Activation of adherent neutrophils causes them to convert from selectin-mediated rolling to integrin-mediated immobilisation and migration. Migration is known to depend on formation and redistribution of filamentous (F) actin, but although immobilisation in seconds parallels early cortical actin polymerisation, no link has been proven. We tested the effect of the actin-polymerising agent jasplakinolide (10 microM) on adhesive and mechanical properties of neutrophils. Pretreated cells were able to adhere and roll on immobilised platelets in a flow-based adhesion assay, but whereas untreated rolling cells became immobilised in seconds when chemotactic formyl peptide (fMLP, 0.1 microM) was superfused over them, the cells treated with jasplakinolide continued rolling. Pretreatment with jasplakinolide also blocked de novo expression of integrin CD11b and shape change which otherwise occurred in minutes after treatment with fMLP. Jasplakinolide directly caused actin polymerisation within neutrophils, evidenced by a marked increase in rigidity (resistance to aspiration into a 5 microm micropipette) and increase in association of actin with the Triton-insoluble cytoskeleton. These results indicate that rearrangement of the actin cytoskeleton regulates integrin-mediated adhesion of activated neutrophils, as well as their migration and mechanical properties.
黏附性中性粒细胞的激活会使其从选择素介导的滚动转变为整合素介导的固定和迁移。已知迁移依赖于丝状（F）肌动蛋白的形成和重新分布，尽管数秒内的固定与早期皮质肌动蛋白聚合同时发生，但尚未证实两者之间存在联系。我们测试了肌动蛋白聚合剂茉莉酮酸甲酯（10微摩尔）对中性粒细胞黏附及力学特性的影响。在基于流动的黏附试验中，预处理的细胞能够在固定的血小板上黏附并滚动，但是当趋化性甲酰肽（fMLP，0.1微摩尔）灌注到未处理的滚动细胞上时，它们会在数秒内固定下来，而用茉莉酮酸甲酯处理的细胞则继续滚动。用茉莉酮酸甲酯预处理还会阻断整合素CD11b的从头表达以及形态变化，而这些变化在fMLP处理后几分钟内通常会发生。茉莉酮酸甲酯直接导致中性粒细胞内的肌动蛋白聚合，这可通过硬度（对吸入5微米微量移液器的阻力）显著增加以及肌动蛋白与不溶于曲拉通的细胞骨架的结合增加得到证明。这些结果表明，肌动蛋白细胞骨架的重排调节了活化中性粒细胞整合素介导的黏附及其迁移和力学特性。
