Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.
Mol Biol Cell. 2011 Sep;22(18):3355-65. doi: 10.1091/mbc.E11-02-0165. Epub 2011 Jul 27.
Caldesmon (CaD) is an important actin modulator that associates with actin filaments to regulate cell morphology and motility. Although extensively studied in cultured cells, there is little functional information regarding the role of CaD in migrating cells in vivo. Here we show that nonmuscle CaD is highly expressed in both premigratory and migrating cranial neural crest cells of Xenopus embryos. Depletion of CaD with antisense morpholino oligonucleotides causes cranial neural crest cells to migrate a significantly shorter distance, prevents their segregation into distinct migratory streams, and later results in severe defects in cartilage formation. Demonstrating specificity, these effects are rescued by adding back exogenous CaD. Interestingly, CaD proteins with mutations in the Ca(2+)-calmodulin-binding sites or ErK/Cdk1 phosphorylation sites fail to rescue the knockdown phenotypes, whereas mutation of the PAK phosphorylation site is able to rescue them. Analysis of neural crest explants reveals that CaD is required for the dynamic arrangements of actin and, thus, for cell shape changes and process formation. Taken together, these results suggest that the actin-modulating activity of CaD may underlie its critical function and is regulated by distinct signaling pathways during normal neural crest migration.
钙调蛋白（CaD）是一种重要的肌动蛋白调节剂，它与肌动蛋白丝结合，调节细胞形态和运动。尽管在培养细胞中进行了广泛的研究，但关于 CaD 在体内迁移细胞中的作用的功能信息很少。在这里，我们表明非肌肉 CaD 在 Xenopus 胚胎的前迁移和迁移颅神经嵴细胞中高度表达。用反义吗啉代寡核苷酸耗尽 CaD 会导致颅神经嵴细胞迁移的距离明显缩短，阻止它们分离成不同的迁移流，并导致软骨形成的严重缺陷。证明特异性，通过添加外源性 CaD 可以挽救这些影响。有趣的是，在 Ca（2+）-钙调蛋白结合位点或 Erk/Cdk1 磷酸化位点发生突变的 CaD 蛋白不能挽救敲低表型，而 PAK 磷酸化位点的突变能够挽救它们。神经嵴外植体的分析表明，CaD 是肌动蛋白动态排列所必需的，因此，对于细胞形状变化和突起形成是必需的。总之，这些结果表明，CaD 的肌动蛋白调节活性可能是其关键功能的基础，并在正常神经嵴迁移过程中受到不同信号通路的调节。
