School of Life Sciences and Technology, Xinxiang Medical University, 601 Jinsui Road, Xinxiang, 453003, Henan, China.
College of Life Sciences, Henan Normal University, Xinxiang, 453007, China.
Mol Cell Biochem. 2017 Nov;435(1-2):175-183. doi: 10.1007/s11010-017-3066-1. Epub 2017 May 23.
The neural cell adhesion molecule (NCAM), a key member of the immunoglobulin-like CAM family, was reported to regulate the migration of bone marrow-derived mesenchymal stem cells (BMSCs). However, the detailed cellular behaviors including lamellipodia formation in the initial step of directional migration remain largely unknown. In the present study, we reported that NCAM affects the lamellipodia formation of BMSCs. Using BMSCs from Ncam knockout mice we found that Ncam deficiency significantly impaired the migration and the directional lamellipodia formation of BMSCs. Further studies revealed that Ncam knockout decreased the activity of cofilin, an actin-cleaving protein, which was involved in directional protrusions. To explore the molecular mechanisms involved, we examined protein tyrosine phosphorylation levels in Ncam knockout BMSCs by phosphotyrosine peptide array analyses, and found that the tyrosine phosphorylation level of β1 integrin, a protein upstream of cofilin, was greatly upregulated in Ncam-deficient BMSCs. Notably, by blocking the function of β1 integrin with RGD peptide or ROCK inhibitor, the cofilin activity and directional lamellipodia formation of Ncam knockout BMSCs could be rescued. Finally, we found that the effect of NCAM on tyrosine phosphorylation of β1 integrin was independent of the fibroblast growth factor receptor. These results indicated that NCAM regulates directional lamellipodia formation of BMSCs through β1 integrin signal-mediated cofilin activity.
神经细胞黏附分子（NCAM）是免疫球蛋白样 CAM 家族的一个关键成员，据报道其可以调节骨髓间充质干细胞（BMSCs）的迁移。然而，其在定向迁移初始阶段中细胞伪足形成等详细的细胞行为仍知之甚少。在本研究中，我们报道 NCAM 影响 BMSCs 的伪足形成。通过 Ncam 基因敲除小鼠的 BMSCs，我们发现 Ncam 缺失显著抑制 BMSCs 的迁移和定向伪足形成。进一步的研究表明，Ncam 缺失降低了肌动蛋白切割蛋白—胞质分裂蛋白（cofilin）的活性，该蛋白参与定向突起的形成。为了探讨涉及的分子机制，我们通过磷酸酪氨酸肽阵列分析检测 Ncam 基因敲除 BMSCs 中的蛋白酪氨酸磷酸化水平，发现 cofilin 上游蛋白—β1 整合素的酪氨酸磷酸化水平在 Ncam 缺陷的 BMSCs 中显著上调。值得注意的是，通过 RGD 肽或 ROCK 抑制剂阻断 β1 整合素的功能，可恢复 Ncam 基因敲除 BMSCs 中的 cofilin 活性和定向伪足形成。最后，我们发现 NCAM 对 β1 整合素的酪氨酸磷酸化的影响不依赖于成纤维细胞生长因子受体。这些结果表明，NCAM 通过 β1 整合素信号介导的 cofilin 活性调节 BMSCs 的定向伪足形成。
