Fujibuchi Taketsugu, Abe Yasuhito, Takeuchi Takashi, Imai Yoshinori, Kamei Yoshiaki, Murase Ryuichi, Ueda Norifumi, Shigemoto Kazuhiro, Yamamoto Haruyasu, Kito Katsumi
Division of Molecular Pathology, Department of Pathology, National University Corporation, Ehime University School of Medicine, Toh-on, Ehime 791-0295, Japan.
Biochem Biophys Res Commun. 2005 Feb 4;327(1):268-75. doi: 10.1016/j.bbrc.2004.11.156.
The actin cytoskeleton plays a fundamental role in configuring cell shapes and movements. Actin interacting protein 1 (AIP1)/tryptophan-aspartate-repeat protein 1 (WDR1) induces actin severing and disassembly cooperating with ADF/cofilin. We found that mitotic cell flattening but not rounding was manifested by suppression of AIP1/WDR1 in cells. This mitotic cell flattening was not due to any changes in phosphorylation and distribution of cofilin in cells. We carried out a direct observation of actin filament severing/disassembly assay and found that phosphorylated cofilin still somewhat severs/disassembles actin filaments and that AIP1/WDR1 effaces this in vitro. We suggest that the phosphorylation of ADF/cofilin will be insufficient to completely inhibit actin turnover during mitosis, and that AIP1/WDR1 could abort the severing/disassembly activity somewhat still carried out due to phosphorylated ADF/cofilin. This mechanism could be required to induce cell morphologic changes, especially mitotic cell rounding.
肌动蛋白细胞骨架在塑造细胞形状和运动中起着基本作用。肌动蛋白相互作用蛋白1（AIP1）/色氨酸-天冬氨酸重复蛋白1（WDR1）与ADF/丝切蛋白协同作用诱导肌动蛋白切断和去组装。我们发现，细胞中AIP1/WDR1的抑制表现为有丝分裂细胞变平而非变圆。这种有丝分裂细胞变平并非由于细胞中丝切蛋白的磷酸化和分布发生任何变化所致。我们对肌动蛋白丝切断/去组装试验进行了直接观察，发现磷酸化的丝切蛋白仍能在一定程度上切断/去组装肌动蛋白丝，而AIP1/WDR1在体外消除了这种作用。我们认为，ADF/丝切蛋白的磷酸化不足以在有丝分裂期间完全抑制肌动蛋白周转，并且AIP1/WDR1可以中止因磷酸化的ADF/丝切蛋白仍在进行的某种程度的切断/去组装活性。这种机制可能是诱导细胞形态变化，尤其是有丝分裂细胞变圆所必需的。
