State Key Laboratory of Genetic Engineering and Collaborative Innovation Center of Genetics and Development, School of Life Sciences and Zhongshan Hospital, Fudan University, Shanghai, 200438, PR China.
Zhengzhou Revogene Inc, Zhengzhou, 450000, PR China.
Biochimie. 2019 Jul;162:55-65. doi: 10.1016/j.biochi.2019.04.003. Epub 2019 Apr 6.
The homeoprotein Msx1 plays a critical role in embryonic patterning, particularly to maintain myogenic progenitor cell fate. However, the mechanisms underlying Msx1-mediated inhibition of myogenesis remain largely unknown. Here, we show that Msx1 cooperates with the protein kinase C-related kinase 1 (Pkn1), a member of the protein kinase C-related kinase family, to prevent the terminal differentiation of myogenic precursor cells. In mouse C2C12 cells, Pkn1 knockout partly impaired Msx1-mediated inhibition of myogenic differentiation, indicating a role for Pkn1 in this process. Furthermore, we found that Pkn1 was required for Msx1 enrichment at the promoter of Myf5, a myogenic regulatory gene. In Pkn1 knockout cells, this reduced Msx1 enrichment at the Myf5 promoter coincided with attenuated repression of Myf5 transcription. Together with our observation that Msx1 and Pkn1 were associated in a protein complex, these findings strongly suggest that Msx1 cooperates with Pkn1 to down-regulate Myf5 and, therefore, prevent the differentiation of myogenic precursor cells. Collectively, our data provide key insights into the mechanisms underlying Msx1 function in the prevention of myogenic differentiation.
同源盒蛋白 Msx1 在胚胎模式形成中发挥着关键作用，特别是维持成肌祖细胞的命运。然而，Msx1 介导的成肌抑制的机制在很大程度上仍然未知。在这里，我们表明 Msx1 与蛋白激酶 C 相关激酶 1（Pkn1）合作，阻止成肌前体细胞的终末分化。在小鼠 C2C12 细胞中，Pkn1 缺失部分损害了 Msx1 介导的成肌分化抑制，表明 Pkn1 在这个过程中起作用。此外，我们发现 Pkn1 是 Msx1 在肌调节基因 Myf5 启动子处富集所必需的。在 Pkn1 缺失的细胞中，这种减少的 Msx1 在 Myf5 启动子处的富集与 Myf5 转录的抑制减弱相吻合。结合我们观察到 Msx1 和 Pkn1 在蛋白复合物中相互关联，这些发现强烈表明 Msx1 与 Pkn1 合作下调 Myf5，从而阻止成肌前体细胞的分化。总的来说，我们的数据为 Msx1 在防止成肌分化中的作用的机制提供了重要的见解。
