Spatial regulation of actin dynamics: a tropomyosin-free, actin-rich compartment at the leading edge
Spatial regulation of actin dynamics: a tropomyosin-free, actin-rich compartment at the leading edge
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DOI：
10.1242/jcs.00147
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发表时间：
2002-12-01
影响因子：
4
通讯作者：
Hitchcock-DeGregori, SE
中科院分区：
文献类型：
--
作者：
DesMarais, V;Ichetovkin, I;Hitchcock-DeGregori, SE
短的、分支的肌动蛋白丝的网络的快速聚合发生在迁移细胞的前缘，这是一个富含肌动蛋白聚合的激活剂如Arp 2/3复合物和cofilin的隔室。细胞内其他部位的肌动蛋白丝长而不分枝。这里报道的结果表明，在这些不同的actincontaining区域的原肌球蛋白的存在或不存在，有助于建立功能不同的肌动蛋白含隔间在cell.Tropomyosin，Arp 2/3复合物和cofilin功能的抑制剂，是本地化的肌动蛋白丝，Arp 2/3复合物，并在MTLn 3细胞，迅速扩展后EGF刺激的扁平板状伪足的肌动蛋白丝的自由倒刺端。所有肌球蛋白亚型检查使用间接免疫荧光相对缺席的动态前缘室，但共定位与肌动蛋白结构更深的板状伪足和应力纤维。体外光学显微镜分析显示，原肌球蛋白保护肌动蛋白丝从cofilin切断。结果表明，原肌球蛋白膜下的无肌动蛋白丝可以参与快速，动态的过程，依赖于Arp 2/3复合物和ADF/cofilin的活性之间的相互作用，原肌球蛋白抑制在细胞的其他地方。
Rapid polymerization of a network of short, branched actin filaments takes place at the leading edge of migrating cells, a compartment enriched in activators of actin polymerization such as the Arp2/3 complex and cofilin. Actin filaments elsewhere in the cell are long and unbranched. Results reported here show that the presence or absence of tropomyosin in these different actincontaining regions helps establish functionally distinct actin-containing compartments in the cell.Tropomyosin, an inhibitor of the Arp2/3 complex and cofilin function, was localized in relation to actin filaments, the Arp2/3 complex, and free barbed ends of actin filaments in MTLn3 cells, which rapidly extend flat lamellipodia following EGF stimulation. All tropornyosin isoforms examined using indirect immunolluorescence were relatively absent from the dynamic leading edge compartment, but did colocalize with actin structures deeper in the lamellipodium and in stress fibers. An in vitro light microscopy assay revealed that tropomyosin protects actin filaments from cofilin severing. The results suggest that tropomyosin-free actin filaments under the membrane can participate in rapid, dynamic processes that depend on interactions between the activities of the Arp2/3 complex and ADF/cofilin that tropomyosin inhibits elsewhere in the cell.