Abstract：
Muscle development is a multistep process regulated by diverse gene networks, and circRNAs are considered novel regulators mediating myogenesis. Here, we systematically analyzed the role and underlying regulatory mechanisms of circRBBP7 in myoblast proliferation and differentiation. Results showed that circRBBP7 has a typical circular structure and encodes a 13 -kDa protein. By performing circRBBP7 overexpression and RNA interference, we found that the function of circRBBP7 was positively correlated with the proliferation and differentiation of myoblasts. Using RNA sequencing, we identified 1633 and 532 differentially expressed genes (DEGs) during myoblast proliferation or differentiation, respectively. The DEGs were found mainly enriched in cell cycle- and skeletal muscle development-related pathways, such as the MDM2/p53 and PI3K-Akt signaling pathways. Further co-IP and IF co-localization analysis revealed that VEGFR-1 is a target of circRBBP7 in myoblasts. qRT-PCR and WB analysis further confirmed the positive correlation between VEGFR-1 and circRBBP7. Moreover, we found that in vivo transfection of circRBBP7 into injured muscle tissues significantly promoted the regeneration and repair of myofibers in mice. Therefore, we speculate that circRBBP7 may affect the activity of MDM2 by targeting VEGFR-1, altering the expression of muscle development-related genes by mediating p53 degradation, and ultimately promoting myoblast development and muscle regeneration. This study provides essential evidence that circRBBP7 can serve as a potential target for myogenesis regulation and a reference for the application of circRBBP7 in cattle genetic breeding and muscle injury treatment.
摘要：
肌肉发育是由多种基因网络调控的多步骤过程,和circRNAs被认为是介导肌肉发生的新型调节因子。这里,我们系统分析了circRBBP7在成肌细胞增殖和分化中的作用和潜在的调控机制。结果表明，circRBBP7具有典型的环状结构，编码13kDa蛋白。通过进行circRBBP7过表达和RNA干扰，我们发现circRBBP7的功能与成肌细胞的增殖和分化呈正相关。使用RNA测序，我们鉴定了成肌细胞增殖或分化过程中的1633和532个差异表达基因（DEG），分别。发现DEGs主要富集在细胞周期和骨骼肌发育相关途径中，如MDM2/p53和PI3K-Akt信号通路。进一步的co-IP和IF共定位分析显示VEGFR-1是成肌细胞中circRBBP7的靶标。qRT-PCR和WB分析进一步证实了VEGFR-1和circRBBP7之间的正相关。此外，我们发现，体内转染circRBBP7到损伤的肌肉组织显著促进小鼠肌纤维的再生和修复。因此,我们推测circRBBP7可能通过靶向VEGFR-1影响MDM2的活性，通过介导p53降解改变肌肉发育相关基因的表达，并最终促进成肌细胞发育和肌肉再生。这项研究提供了必要的证据，表明circRBBP7可以作为肌肉发生调节的潜在靶标，并为circRBBP7在牛遗传育种和肌肉损伤治疗中的应用提供了参考。
