C3G (also known as RAPGEF1) plays a role in cell differentiation and is essential for early embryonic development in mice. In this study, we identify C3G as a centrosomal protein that colocalizes with cenexin (also known as ODF2) at the mother centriole in interphase cells. C3G interacts with cenexin through its catalytic domain, and the two proteins show interdependence for localization to the centrosome. C3G depletion causes a decrease in cellular cenexin levels. Centrosomal localization of C3G is lost as myocytes differentiate to form myotubes. Depletion of C3G by CRISPR/Cas9 results in the formation of supernumerary centrioles, whereas overexpression of C3G, or expression of a catalytically active C3G deletion construct, inhibits centrosome duplication. Cilium length is increased in C3G knockout cells, and this phenotype is reverted upon reintroduction of C3G or its catalytic domain alone. Association of C3G with the basal body is dynamic, decreasing upon serum starvation and increasing upon re-entry into the cell cycle. C3G inhibits cilium formation and length, and this inhibition is dependent on C3G catalytic activity. We conclude that C3G regulates centrosome duplication and maintains ciliary homeostasis, properties that could be important for its role in embryonic development.

C3G（也称为 RAPGEF1）在细胞分化中发挥作用，对小鼠早期胚胎发育至关重要。在这项研究中，我们将 C3G 鉴定为一种中心体蛋白，它与间期细胞中母体中心粒的 cenexin（也称为 ODF2）共定位。C3G 通过其催化结构域与 cenexin 相互作用，这两种蛋白质在定位到中心体时表现出相互依赖性。C3G 耗竭导致细胞 cenexin 水平降低。随着肌细胞分化形成肌管，C3G 的中心体定位丢失。CRISPR/Cas9 对 C3G 的消耗导致形成多余的中心粒，而 C3G 的过表达或催化活性 C3G 缺失构建体的表达抑制中心体复制。C3G敲除细胞的纤毛长度增加，并且仅在重新引入 C3G 或其催化结构域后，这种表型就会恢复。C3G 与基底体的结合是动态的，血清饥饿时减少，重新进入细胞周期时增加。C3G 抑制纤毛的形成和长度，这种抑制取决于 C3G 的催化活性。我们得出结论，C3G 调节中心体复制并维持纤毛稳态，这些特性可能对其在胚胎发育中的作用很重要。