Microtubule-binding proteins provide an alternative and vital pathway to the functional diversity of microtubules. Considerable work is still required to understand the complexities of microtubule-associated cellular processes and to identify novel microtubule-binding proteins. In this study, we identify Bcl2-associated athanogene cochaperone 6 (BAG6) as a novel microtubule-binding protein and reveal that it is crucial for primary ciliogenesis. By immunofluorescence we show that BAG6 largely colocalizes with intracellular microtubules and by co-immunoprecipitation we demonstated that it can interact with α-tubulin. Additionally, both the UBL and BAG domains of BAG6 are indispensable for its interaction with α-tubulin. Moreover, the assembly of primary cilia in RPE-1 cells is significantly inhibited upon the depletion of BAG6. Notably, BAG6 inhibition leads to an abnormal G0/G1 transition during the cell cycle. In addition, BAG6 colocalizes and interactes with the centrosomal protein γ-tubulin, suggesting that BAG6 might regulate primary ciliogenesis through its action in centrosomal function. Collectively, our findings suggest that BAG6 is a novel microtubule-bindng protein crucial for primary ciliogenesis.

中文翻译：

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BAG6是一种新型的微管结合蛋白，可通过调节细胞周期并与γ-微管蛋白相互作用来调节纤毛形成。

微管结合蛋白为微管的功能多样性提供了另一种重要途径。为了理解与微管相关的细胞过程的复杂性并鉴定新的微管结合蛋白，仍需要大量工作。在这项研究中，我们确定Bcl2相关的硫基因伴侣蛋白6（BAG6）作为一种新型的微管结合蛋白，并揭示了它对原发性纤毛发生至关重要。通过免疫荧光，我们显示BAG6在很大程度上与细胞内微管共定位，并且通过共免疫沉淀，我们证明BAG6可以与α-微管蛋白相互作用。另外，BAG6的UBL和BAG结构域对于与α-微管蛋白的相互作用都是必不可少的。此外，在耗尽BAG6后，RPE-1细胞中的初级纤毛的组装受到显着抑制。尤其，BAG6抑制导致细胞周期中异常的G0 / G1过渡。此外，BAG6与中心体蛋白γ-微管蛋白共定位并相互作用，这表明BAG6可能通过其在中心体功能中的作用来调节原发性纤毛发生。总的来说，我们的发现表明BAG6是一种新型的微管结合蛋白，对原发性纤毛发生至关重要。