荷兰乌得勒支大学Anna Akhmanova等研究人员合作发现，CAMSAP和成核促进因子控制微管从γ-TuRC释放。这一研究成果于2024年2月29日在线发表在国际学术期刊《自然—细胞生物学》上。

研究人员表示，γ-微管蛋白环复合体（γ-TuRC）是主要的微管成核因子。成核后，微管可从γ-TuRC中释放出来，并通过其他蛋白质（如CAMSAP）稳定下来，但人们对负端调节途径之间的生化交叉作用知之甚少。

研究人员利用纯化的成分在体外重建了这一过程。研究人员发现，所有CAMSAP都能与γ-TuRC连接的微管负端结合。CAMSAP2和CAMSAP3能装饰和稳定生长中的负端，而负端追踪蛋白CAMSAP1却不能，它们能诱导微管从γ-TuRC中释放。CDK5RAP2（一种γ-TuRC互作因子）和CLASP2（一种微管生长调节因子）强烈刺激了依赖于γ-TuRC的微管成核，但只有CDK5RAP2抑制了CAMSAP与γ-TuRC锚定的负端结合及其释放。

CDK5RAP2还提高了含 γ-微管蛋白复合物在微管加帽试验中对13根而非14根原丝微管的选择性。细胞中的基因敲除和过表达实验表明，CDK5RAP2可抑制脱离微管组织中心的与CAMSAP2结合的微管的形成。研究人员认为，CAMSAP可将新成核的微管从γ-TuRC中释放出来，而成核促进因子可对这一过程进行不同程度的调控。

附：英文原文

Title: CAMSAPs and nucleation-promoting factors control microtubule release from γ-TuRC

Author: Rai, Dipti, Song, Yinlong, Hua, Shasha, Stecker, Kelly, Monster, Jooske L., Yin, Victor, Stucchi, Riccardo, Xu, Yixin, Zhang, Yaqian, Chen, Fangrui, Katrukha, Eugene A., Altelaar, Maarten, Heck, Albert J. R., Wieczorek, Michal, Jiang, Kai, Akhmanova, Anna

Issue&Volume: 2024-02-29

Abstract: γ-Tubulin ring complex (γ-TuRC) is the major microtubule-nucleating factor. After nucleation, microtubules can be released from γ-TuRC and stabilized by other proteins, such as CAMSAPs, but the biochemical cross-talk between minus-end regulation pathways is poorly understood. Here we reconstituted this process in vitro using purified components. We found that all CAMSAPs could bind to the minus ends of γ-TuRC-attached microtubules. CAMSAP2 and CAMSAP3, which decorate and stabilize growing minus ends but not the minus-end tracking protein CAMSAP1, induced microtubule release from γ-TuRC. CDK5RAP2, a γ-TuRC-interactor, and CLASP2, a regulator of microtubule growth, strongly stimulated γ-TuRC-dependent microtubule nucleation, but only CDK5RAP2 suppressed CAMSAP binding to γ-TuRC-anchored minus ends and their release. CDK5RAP2 also improved selectivity of γ-tubulin-containing complexes for 13- rather than 14-protofilament microtubules in microtubule-capping assays. Knockout and overexpression experiments in cells showed that CDK5RAP2 inhibits the formation of CAMSAP2-bound microtubules detached from the microtubule-organizing centre. We conclude that CAMSAPs can release newly nucleated microtubules from γ-TuRC, whereas nucleation-promoting factors can differentially regulate this process.

DOI: 10.1038/s41556-024-01366-2

Source: https://www.nature.com/articles/s41556-024-01366-2