Role of the Low-Density Lipoprotein Receptor-Related Protein-1 in Regulation of Chondrocyte Differentiation
Role of the Low-Density Lipoprotein Receptor-Related Protein-1 in Regulation of Chondrocyte Differentiation
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DOI：
10.1002/jcp.21930
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发表时间：
2010-01-01
影响因子：
5.6
通讯作者：
Takigawa, Masaharu
中科院分区：
文献类型：
--
作者：
Kawata, Kazumi;Kubota, Satoshi;Takigawa, Masaharu
低密度脂蛋白受体相关蛋白 1 (LRP1) 被称为内吞和信号传输受体。我们之前报道了LRP1在软骨组织和软骨细胞中的基因表达和定位，但其在软骨细胞分化中的作用仍有待研究。在这里，为了解决这个问题，我们采用RNAi策略来敲低软骨细胞中的Irpl，并获得了表明其中关键作用的发现。 IrpI 敲低的结果是，聚集蛋白聚糖和 col2a1 mRNA 水平降低。然而，col10a1或mmp13 mRNA的含量却相当增加。在此条件下，我们对 Axing 进行了启动子测定，已知 Axing 是由 WNT/β-连环蛋白 (β cat) 信号通路的激活诱导的。因此，我们发现Axing启动子活性在Irpl敲低细胞中增强。此外，当 WNT3a 或 SB216763 激活软骨细胞中的 WNT/β-连环蛋白途径（抑制 GSK3 β 磷酸化）时，聚集蛋白聚糖和 col2a1 的 mRNA 水平降低，而 mmp13 的 mRNA 水平升高。此外，Irp1 敲低细胞中磷酸化蛋白激酶 C (PKC) zeta 的水平也有所降低。当选择性抑制 PKC zeta 的磷酸化时，聚集蛋白聚糖和 col2a1 mRNA 水平下降，而 mmp13 mRNA 水平增加。这些数据表明，LRP1 作为细胞信号传导的关键介质，在保留软骨细胞的成熟表型方面发挥着显着的作用。我们的研究结果还表明，软骨内骨化过程中肥大的发生似乎特别依赖于 LRP1 启动的 WNT 和 PKC 信号传导。 J.细胞。生理学。 222: 138-148, 2010。(C) 2009 Wiley-Liss, Inc.
The low-density lipoprotein receptor-related protein 1 (LRP1) is known as an endocytic and signal transmission receptor. We formerly reported the gene expression and the localization of LRP1 in cartilage tissue and chondrocytes, but its roles in the differentiation of chondrocytes remained to be investigated. Here, in order to address this issue, we employed RNAi strategy to knockdown Irpl in chondrocytic cells and obtained findings indicating a critical role therein. As a result of IrpI knockdown, aggrecan and col2a1 mRNA levels were decreased. However, that of col10a1 or mmp13 mRNA was rather increased. Under this condition, we performed a promoter assay for Axing, which is known to be induced by activation of the WNT/beta-catenin (beta cat) signaling pathway. Thereby, we found that Axing promoter activity was enhanced in the Irpl knockdown cells. Furthermore, when the WNT/beta-catenin pathway was activated in chondrocytic cells by WNT3a or SB216763, which inhibits the phosphorylation of GSK3 beta, the mRNA levels of aggrecan and col2a1 were decreased, whereas that of mmp13 was increased. Additionally, the level of phosphorylated protein kinase C (PKC) zeta was also decreased in the Irp1 knockdown cells. When the phosphorylation of PKC zeta was selectively inhibited, aggrecan and col2a1 mRNA levels decreased, whereas the mmp13 mRNA level increased. These data demonstrate that LRP1 exerts remarkable effects to retain the mature phenotype of chondrocytes as a critical mediator of cell signaling. Our findings also indicate that the onset of hypertrophy during endochondral ossification appears to be particularly dependent on the WNT and PKC signaling initiated by LRP1. J. Cell. Physiol. 222: 138-148, 2010. (C) 2009 Wiley-Liss, Inc.