Irx3 and Bmp2 regulate mouse mesenchymal cell chondrogenic differentiation in both a Sox9-dependent and -independent manner
Irx3 and Bmp2 regulate mouse mesenchymal cell chondrogenic differentiation in both a Sox9-dependent and -independent manner
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Irx3和Bmp2以Sox9依赖性和非依赖性方式调节小鼠间充质细胞软骨形成分化
DOI：
10.1002/jcp.25776
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Wakitani S
中科院分区：
文献类型：
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作者：
Tamamura Y;Katsube K;Mera H;Itokazu M;Wakitani S
Sox 9是软骨发育的主要调节因子，控制着细胞从间充质细胞分化为软骨细胞的命运决定。此外，Sox 9调节软骨细胞的增殖和分化，以及软骨特异性蛋白聚糖的产生。软骨发育中是否存在Sox9非依赖性机制仍有待确定。在这里，我们试图通过使用小鼠软骨细胞系N1511的微阵列分析来确定参与这种假定机制的基因。我们首先关注Bmp2处理后表达上调的转录因子，随后用Sox9 siRNA处理不会改变这些转录因子。其中，我们选择了软骨形成的正调控因子，并将易洛魁相关同源框3（Irx3）确定为候选基因之一。Irx3表达随着软骨细胞终末分化而逐渐增加，与Sox9表达呈反比，并促进Bmp2处理后间充质细胞的软骨分化。此外，Irx3通过在Sox9表达降低的情况下上调epiphycan和lumican的表达，部分挽救了受损的软骨形成。最后，Irx3被证明与Bmp2信号一起激活p38 MAPK通路，这反过来刺激Sox9表达，以及以Sox9非依赖性方式表达epiphycan和lumican。这些结果表明，Irx3代表了间充质细胞的一种新的软骨形成因子，与Bmp 2介导的信号转导协同作用，并独立于与Sox 9介导的调控相关的转录机制调节软骨形成。
Sox9, a master regulator of cartilage development, controls the cell fate decision to differentiate from mesenchymal to chondrogenic cells. In addition, Sox9 regulates the proliferation and differentiation of chondrocytes, as well as the production of cartilage‐specific proteoglycans. The existence of Sox9‐independent mechanisms in cartilage development remains to be determined. Here, we attempted to identify genes involved in such putative mechanisms via microarray analysis using a mouse chondrogenic cell line, N1511. We first focused on transcription factors that exhibited upregulated expression following Bmp2 treatment, which was not altered by subsequent treatment with Sox9 siRNA. Among these, we selected positive regulators for chondrogenesis and identified Iroquois‐related homeobox 3 (Irx3) as one of the candidate genes. Irx3 expression gradually increased with chondrocyte terminal differentiation in a reciprocal manner to Sox9 expression, and promoted the chondrogenic differentiation of mesenchymal cells upon Bmp2 treatment. Furthermore, Irx3 partially rescued impaired chondrogenesis by upregulating the expression of epiphycan and lumican under reducedSox9expression. Finally, Irx3 was shown to act in concert with Bmp2 signaling to activate the p38 MAPK pathway, which in turn stimulatedSox9expression, as well as the expression of epiphycan and lumican in a Sox9‐independent manner. These results indicate that Irx3 represents a novel chondrogenic factor of mesenchymal cells, acts synergistically with Bmp2‐mediated signaling, and regulates chondrogenesis independent of the transcriptional machinery associated with Sox9‐mediated regulation.