The differentiation of myoblasts plays a key role in the growth of biological individuals and the reconstruction of muscle tissue. Several microRNAs are significantly upregulated during the differentiation of myoblasts and their target genes have been explored. However, the molecular mechanisms underlying the transcriptional regulation of microRNAs remain elusive. In the present study, we found that the expression of miR-133a is increased during the differentiation of C2C12 myoblasts. miR-133a mimic is sufficient to induce the biogenesis of mitochondria and differentiation of C2C12 myoblasts whereas miR-133a inhibitor abolishes cell differentiation. Using CRISPR affinity purification in situ of regulatory elements (CAPTURE) technique, we further dissected the regulatory mechanisms of miR-133a expression and found that KAP1-associated transcription complex accounts for the suppression of miR-133a in C2C12 myoblasts. Knockdown of KAP1 increased the expression of miR-133a, which contributed to the biogenesis of mitochondria and differentiation of C2C12 myoblasts. To our knowledge, this is the first study using the CAPTURE technology to identify the regulatory factors of miR-133a during cell differentiation, which may provide new ideas for understanding the precision regulatory machinery of microRNAs during different biological processes.

成肌细胞的分化在生物个体的生长和肌肉组织的重建中起着关键作用。几种微RNA在成肌细胞分化过程中显着上调，并且已经探索了它们的靶基因。然而，microRNA 转录调控的分子机制仍然难以捉摸。在本研究中，我们发现 miR-133a 的表达在 C2C12 成肌细胞分化过程中增加。miR-133a 模拟物足以诱导线粒体的生物发生和 C2C12 成肌细胞的分化，而 miR-133a 抑制剂会消除细胞分化。使用 CRISPR 亲和纯化原位调节元件 (CAPTURE) 技术，我们进一步剖析了 miR-133a 表达的调控机制，发现 KAP1 相关转录复合物是 C2C12 成肌细胞中 miR-133a 抑制的原因。KAP1 的敲低增加了 miR-133a 的表达，这有助于线粒体的生物发生和 C2C12 成肌细胞的分化。据我们所知，这是首个利用CAPTURE技术识别细胞分化过程中miR-133a调控因子的研究，可能为理解microRNA在不同生物过程中的精准调控机制提供新思路。