Limited functional redundancy and oscillation of cyclins in multinucleated Ashbya gossypii fungal cells
Limited functional redundancy and oscillation of cyclins in multinucleated Ashbya gossypii fungal cells
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DOI：
10.1128/ec.00273-06
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发表时间：
2007-03-01
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影响因子：
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通讯作者：
Gladfelter, Amy S.
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文献类型：
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作者：
Hungerbuehler, A. Katrin;Philippsen, Peter;Gladfelter, Amy S.
细胞周期蛋白的行为还没有系统地研究在多核细胞与异步有丝分裂。细胞周期蛋白是典型的振荡细胞周期蛋白，但目前还不清楚如何波动的蛋白梯度可以建立在多核细胞中，其中细胞核在分裂周期的不同阶段共享细胞质。以前的工作在A。gossypii，一种丝状真菌，细胞核在一个共同的细胞质中异步分裂，证明了一个G1和一个B型细胞周期蛋白在整个分裂周期中的丰度不波动。我们对A. gossypii中的细胞周期蛋白，以确定是否有任何细胞周期蛋白在整个细胞周期中显示出周期性丰度，并检查细胞周期蛋白在这种细胞环境中是否表现出功能冗余。我们本地化的所有G1和B型细胞周期蛋白，并特别发现，只有AgClb 5/6p在分裂周期中的亚细胞定位的变化。AgClb 5/6p在中期-后期转换时以D-box依赖的方式从核中丢失。这些数据表明，有效的核自主蛋白质降解可以发生在驻留在共同的细胞质中的多核细胞内。我们已经证明A. gossypii是必需基因，表明在这个多核系统中有最小的功能冗余。此外，我们已经确定了一个周期蛋白，AgClb 3/4p，这是必不可少的孢子形成。我们提出，不同的细胞周期蛋白在细胞核中的同居导致了增强的底物特异性和有限的功能冗余类细胞周期蛋白在多核细胞。
Cyclin protein behavior has not been systematically investigated in multinucleated cells with asynchronous mitoses. Cyclins are canonical oscillating cell cycle proteins, but it is unclear how fluctuating protein gradients can be established in multinucleated cells where nuclei in different stages of the division cycle share the cytoplasm. Previous work in A. gossypii, a filamentous fungus in which nuclei divide asynchronously in a common cytoplasm, demonstrated that one G1 and one B-type cyclin do not fluctuate in abundance across the division cycle. We have undertaken a comprehensive analysis of all G1 and B-type cyclins in A. gossypii to determine whether any of the cyclins show periodic abundance across the cell cycle and to examine whether cyclins exhibit functional redundancy in such a cellular environment. We localized all G1 and B-type cyclins and notably found that only AgClb5/6p varies in subcellular localization during the division cycle. AgClb5/6p is lost from nuclei at the meta-anaphase transition in a D-box-dependent manner. These data demonstrate that efficient nuclear autonomous protein degradation can occur within multinucleated cells residing in a common cytoplasm. We have shown that three of the five cyclins in A. gossypii are essential genes, indicating that there is minimal functional redundancy in this multinucleated system. In addition, we have identified a cyclin, AgClb3/4p, that is essential only for sporulation. We propose that the cohabitation of different cyclins in nuclei has led to enhanced substrate specificity and limited functional redundancy within classes of cyclins in multinucleated cells.