C9ORF78 partially localizes to centromeres and plays a role in chromosome segregation.
C9ORF78 partially localizes to centromeres and plays a role in chromosome segregation.
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DOI：
10.1016/j.yexcr.2022.113063
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发表时间：
2022-02
影响因子：
3.7
通讯作者：
Radhika Koranne;Kayla M. Brown;Hannah Vandenbroek;W. Taylor
中科院分区：
文献类型：
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作者：
Radhika Koranne;Kayla M. Brown;Hannah Vandenbroek;W. Taylor
C9ORF78是一种在多种真核生物中发现的特征较差的蛋白质。先前的研究表明，C9ORF78在恶性组织中过表达，表明可能参与生长调节途径。对裂变酵母和人类的进一步研究揭示了调节剪接体的潜在功能。在对gfp标记的C9ORF78的研究中，我们观察到在融合生长和/或剥夺血清生长因子的细胞中蛋白质丰度显著降低。血清刺激诱导该蛋白在HeLa细胞中同步再表达。内源蛋白也具有这种效应。过表达E2F1或N-Myc导致C9ORF78表达升高，可能解释了该蛋白的血清依赖性上调。免疫荧光分析表明，C9ORF78定位于细胞核间期，而不是像剪接蛋白那样集中在斑点上。令人惊讶的是，在有丝分裂细胞中，C9ORF78亚群与ACA、Mad1和Ndc80共定位，表明该蛋白与着丝点或着丝粒相关。在有丝分裂检查点激活时，着丝粒/着丝点上的C9ORF78水平也增加。此外，敲低C9ORF78会导致有丝分裂缺陷。这些研究揭示了C9ORF78新的有丝分裂功能和亚细胞定位。
C9ORF78 is a poorly characterized protein found in diverse eukaryotes. Previous work indicated overexpression of C9ORF78 in malignant tissues indicating a possible involvement in growth regulatory pathways. Additional studies in fission yeast and humans uncover a potential function in regulating the spliceosome. In studies of GFP-tagged C9ORF78 we observed a dramatic reduction in protein abundance in cells grown to confluence and/or deprived of serum growth factors. Serum stimulation induced synchronous re-expression of the protein in HeLa cells. This effect was also observed with the endogenous protein. Overexpressing either E2F1 or N-Myc resulted in elevated C9ORF78 expression potentially explaining the serum-dependent upregulation of the protein. Immunofluorescence analysis indicates that C9ORF78 localizes to nuclei in interphase but does not appear to concentrate in speckles as would be expected for a splicing protein. Surprisingly, a subpopulation of C9ORF78 co-localizes with ACA, Mad1 and Ndc80 in mitotic cells suggesting that this protein associates with kinetochores or centromeres. Levels of C9ORF78 at the centromere/kinetochore also increased upon activation of the mitotic checkpoint. Furthermore, knocking-down C9ORF78 caused mitotic defects. These studies uncover novel mitotic function and subcellular localization of C9ORF78.