Characterization of the Rab8-specific membrane traffic route linked to protrusion formation
Characterization of the Rab8-specific membrane traffic route linked to protrusion formation
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DOI：
10.1242/jcs.03275
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发表时间：
2006-12-01
影响因子：
4
通讯作者：
Peranen, Johan
中科院分区：
文献类型：
--
作者：
Hattula, Katarina;Furuhjelm, Johanna;Peranen, Johan
Rab8 对细胞形状具有巨大影响，但其调节的膜运输途径尚不清楚。在这里，我们发现内源性和异位表达的 Rab8 与皱褶膜域产生的巨胞质体相关。这些巨胞质体融合或转变为向细胞中心移动的小管，并从那里再循环回到前缘。这些小管的生物发生取决于肌动蛋白和微管动力学。显性失活 Rab8 突变体的表达或通过 RNA 干扰消除 Rab8 会抑制突起形成，但会促进细胞间粘附和肌动蛋白应力纤维形成，而组成型活性 Rab8-Q67L 的表达则具有相反的作用。 Rab8 定位与 Rab11 和 Arf6 重叠，并且在功能上与 Arf6 相关。我们还证明，Rab8 活性是将转铁蛋白和转铁蛋白受体转运至中心粒周围区域和细胞突起所必需的，并且 Rab8 控制霍乱毒素 B 至高尔基体的转运。最后，Rab8 共定位并特异性结合突触结合蛋白样蛋白 (SIp1/JFC1)，该蛋白参与控制 Rab8 膜动力学。我们认为 Rab8 调节介导突起形成的膜回收途径。
Rab8 has a drastic effect on cell shape, but the membrane trafficking route it regulates is poorly defined. Here, we show that endogenous and ectopically expressed Rab8 is associated with macropinosomes generated at ruffling membrane domains. These macropinosomes fuse or transform into tubules that move toward the cell center, from where they are recycled back to the leading edge. The biogenesis of these tubules is dependent on actin and microtubular dynamics. Expression of dominant-negative Rab8 mutants or depletion of Rab8 by RNA interference inhibit protrusion formation, but promote cell-cell adhesion and actin stress fiber formation, whereas expression of the constitutively active Rab8-Q67L has the opposite effect. Rab8 localization overlaps with both Rab11 and Arf6, and is functionally linked to Arf6. We also demonstrate that Rab8 activity is needed for the transport of transferrin and the transferrin receptor to the pericentriolar region and to cell protrusions, and that Rab8 controls the traffic of cholera toxin B to the Golgi compartment. Finally, Rab8 colocalizes and binds specifically to a synaptotagmin-like protein (SIp1/JFC1), which is involved in controlling Rab8 membrane dynamics. We propose that Rab8 regulates a membrane-recycling pathway that mediates protrusion formation.