Cofilin plays a critical role in IL-8-dependent chemotaxis of neutrophilic HL-60 cells through changes in phosphorylation
Cofilin plays a critical role in IL-8-dependent chemotaxis of neutrophilic HL-60 cells through changes in phosphorylation
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DOI：
10.1189/jlb.0506314
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发表时间：
2007-03-01
影响因子：
5.5
通讯作者：
Suzuki, Kazuhiro
中科院分区：
文献类型：
--
作者：
Hirayama, Akiko;Adachi, Reiko;Suzuki, Kazuhiro
Cofilin是一种普遍存在的肌动蛋白结合蛋白。只有未磷酸化的cofilin结合肌动蛋白并切断或解聚丝状肌动蛋白（F-肌动蛋白），并且cofilin的非活性形式在Ser 3处磷酸化。我们最近报道了cofilin在白细胞产生超氧化物和吞噬中起着调节作用，在本研究中，我们研究了cofilin在嗜中性HL-60细胞趋化性中的作用。IL-8是一种有效的生理趋化因子，它触发质膜下的F-肌动蛋白的快速、瞬时增加以及cofilin的快速去磷酸化和随后的再磷酸化。在本研究中，发现Cofilin磷酸化被S3-R肽抑制，S3-R肽由对应于Cofilin磷酸化位点的一部分的肽和膜可渗透的精氨酸聚合物组成。当S3-R肽被引入嗜酸性细胞时，它们的趋化活性增强，而含有cofilin磷酸化位点的反向序列的对照肽没有增强作用。Cofilin小干扰RNA（siRNA）使Cofilin表达降低约一半，并抑制趋化性。在IL-8刺激的细胞中，未磷酸化的cofilin聚集在F-肌动蛋白周围，并且观察到F-肌动蛋白和磷酸化的cofilin的共定位，但是cofilin定位的这些变化在cofilin siRNA处理的细胞中不太突出。PI-3 K抑制剂wortmannin和LY 294002可抑制趋化性，并抑制IL-8诱导的cofilin去磷酸化和再磷酸化。这些结果表明，未磷酸化的cofilin在白细胞趋化性中起着关键作用，PI-3 K参与控制cofilin的磷酸化/去磷酸化循环。
Cofilin is a ubiquitous, actin-binding protein. Only unphosphorylated cofilin binds actin and severs or depolymerizes filamentous actin (F-actin), and the inactive form of cofilin is phosphorylated at Ser 3. We reported recently that cofilin plays a regulatory role in superoxide production and phagocytosis by leukocytes, and in the present study, we investigated the role of cofilin in the chemotaxis of nentrophilic HL-60 cells. IL-8 is a potent, physiological chemokine, and it triggers a rapid, transient increase in F-actin beneath the Plasma membrane and rapid dephosphorylation and subsequent rephosphorylation of cofilin. In this study, cofilin phosphorylation was found to be inhibited by S3-R peptide, which consists of a peptide corresponding to part of the phosphorylation site of cofilin and a membrane-permeable arginine polymer. When S3-R peptide was introduced into the neutrophilic cells, their chemotactic activity was enhanced, whereas a control peptide that contained an inverted sequence of the phosphorylation site of cofilin had no enhancing effect. Cofilin small interfering RNA (siRNA) decreased cofilin expression by about half and inhibited chemotaxis. In IL-8-stimulated cells, unphosphorylated cofilin accumulated around F-actin, and colocalization of F-actin and phosphorylated cofilin was observed, but these changes in cofilin localization were less prominent in cofilin siRNA-treated cells. The inhibitors of PI-3K wortmannin and LY294002 inhibited the chemotaxis and suppressed IL-8-evoked dephosphorylation and rephosphorylation of cofilin. These results suggested that unphosphorylated cofilin plays a critical role in leukocyte chemotaxis and that PI-3K is involved in the control of the phosphorylation/dephosphorylation cycle of cofilin.