Department of Pediatrics, Leiden University Medical Centre, Leiden, the Netherlands.
Exp Cell Res. 2011 Jun 10;317(10):1411-21. doi: 10.1016/j.yexcr.2011.03.007. Epub 2011 Mar 22.
The canonical Wnt signaling pathway influences the differentiation of mesenchymal cell lineages in a quantitative and qualitative fashion depending on the dose of β-catenin signaling. Adenomatous polyposis coli (Apc) is the critical intracellular regulator of β-catenin turnover. To better understand the molecular mechanisms underlying the role of Apc in regulating the differentiation capacity of skeletal progenitor cells, we have knocked down Apc in the murine mesenchymal stem cell-like KS483 cells by stable expression of Apc-specific small interfering RNA. In routine culture, KSFrt-Apc(si) cells displayed a mesenchymal-like spindle shape morphology, exhibited markedly decreased proliferation and increased apoptosis. Apc knockdown resulted in upregulation of the Wnt/β-catenin and the BMP/Smad signaling pathways, but osteogenic differentiation was completely inhibited. This effect could be rescued by adding high concentrations of BMP-7 to the differentiation medium. Furthermore, KSFrt-Apc(si) cells showed no potential to differentiate into chondrocytes or adipocytes. These results demonstrate that Apc is essential for the proliferation, survival and differentiation of KS483 cells. Apc knockdown blocks the osteogenic differentiation of skeletal progenitor cells, a process that can be overruled by high BMP signaling.
经典 Wnt 信号通路根据β-连环蛋白信号的剂量以定量和定性的方式影响间充质细胞谱系的分化。腺瘤性结肠息肉病基因（APC）是β-连环蛋白周转的关键细胞内调节剂。为了更好地理解 APC 在调节成骨前体细胞分化能力中的作用的分子机制，我们通过稳定表达 APC 特异性小干扰 RNA 使鼠间充质干细胞样 KS483 细胞中的 APC 失活。在常规培养中，KSFrt-Apc(si)细胞呈现出间充质样的纺锤形形态，表现出明显的增殖减少和凋亡增加。APC 敲低导致 Wnt/β-连环蛋白和 BMP/Smad 信号通路的上调，但成骨分化完全被抑制。在分化培养基中添加高浓度的 BMP-7 可以挽救这种影响。此外，KSFrt-Apc(si)细胞没有分化为软骨细胞或脂肪细胞的潜力。这些结果表明 APC 对于 KS483 细胞的增殖、存活和分化是必不可少的。APC 敲低阻断了成骨前体细胞的成骨分化，这一过程可以被高 BMP 信号所推翻。
