Completion of mitosis requires neither fzr/rap nor fzr2, a male germ line-specific Drosophila Cdh1 homolog
Completion of mitosis requires neither fzr/rap nor fzr2, a male germ line-specific Drosophila Cdh1 homolog
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DOI：
10.1016/s0960-9822(02)01074-6
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发表时间：
2002-08-20
期刊：
影响因子：
9.2
通讯作者：
Lehner, CF
中科院分区：
文献类型：
--
作者：
Jacobs, HW;Richter, DO;Lehner, CF
有丝分裂调节因子如securin和cyclins的蛋白水解需要Fizzy（FZY）/Cdc 20和Fizzy相关（FZR）/Hct 1/Cdh 1蛋白[1-5]。芽殖酵母Cdh 1不仅在G1期起作用，而且当Cdh 1是控制晚期有丝分裂和胞质分裂进展的有丝分裂退出网络的靶标时，在退出有丝分裂期间B型细胞周期蛋白降解也是必需的[6，7]。相比之下，在青蛙和果蝇胚胎中的观察表明，在退出有丝分裂过程中不涉及orthopathic FZR [3，8]。然而，在这些研究中未排除少量母体来源的FZR的潜在参与。类似地，鸡Cdh 1（-/-）细胞[9]中报告的严重有丝分裂缺陷的缺失可能由最近鉴定的多个Cdh 1基因[10]来解释。在这里，我们仔细分析了FZR的要求在退出有丝分裂在果蝇，其中，除了FZR，只有一个额外的同源物。我们发现，这个fzr 2基因，虽然在男性生殖细胞系中表达，在有丝分裂期间不表达。此外，通过表征FZR等位基因，我们证明了包括细胞周期蛋白B降解在内的有丝分裂的完成不需要FZR。然而，fzr是一个必需的基因对应的rap位点，和FZR，主要积累在细胞质中，显然是需要在G1期。
Proteolysis of mitotic regulators like securins and cyclins requires Fizzy(FZY)/Cdc20 and Fizzy-related(FZR)/Hct1/Cdh1 proteins [1-5]. Budding yeast Cdh1 acts not only during G1, but is also required for B-type cyclin degradation during exit from mitosis when Cdh1 is a target of the mitotic exit network controlling progression through late mitosis and cytokinesis [6, 7]. In contrast, observations in frog and Drosophila embryos have suggested that the orthologous FZR is not involved during exit from mitosis [3, 8]. However, the potential involvement of minor amounts of maternally derived FZR was not excluded in these studies. Similarly, the reported absence of severe mitotic defects in chicken Cdh1(-/-) cells [9] might be explained by the recent identification of multiple Cdh1 genes [10]. Here, we have carefully analyzed the FZR requirement during exit from mitosis in Drosophila, which, apart from fzr, has only one additional homolog. We find that this fzr2 gene, although expressed in the male germline, is not expressed during mitotic divisions. Moreover, by characterizing fzr alleles, we demonstrate that completion of mitosis including Cyclin B degradation does not require FZR. However, fzr is an essential gene corresponding to the rap locus, and FZR, which accumulates predominantly in the cytoplasm, is clearly required during G1.