Investigation of cell cycle-associated structural reorganization in nucleolar FC/DFCs from mouse MFC cells by electron microscopy
Investigation of cell cycle-associated structural reorganization in nucleolar FC/DFCs from mouse MFC cells by electron microscopy
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通过电子显微镜研究小鼠 MFC 细胞核仁 FC/DFC 中细胞周期相关的结构重组
DOI：
10.1093/jmicro/dfy020
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发表时间：
2018
期刊：
影响因子：
1.8
通讯作者：
Jiao Mingda
中科院分区：
文献类型：
--
作者：
Chen Lingling;Jiao Yang;Guan Xin;Li Xiliang;Feng Yunpeng;Jiao Mingda
随着细胞周期的进展，核仁结构发生变化。它在分裂末期形成，在整个分裂间期维持，在分裂中期解体。纤维中心（FC）、致密纤维组分（DFC）和颗粒组分（GC）是rRNA转录、加工和核糖体组装的基本核仁组织。然而，对这些结构的细胞周期依赖性重组知之甚少。在这项研究中，我们跟踪细胞周期中的核仁结构的电子显微镜（EM）。结果表明，在一个细胞周期中，核仁经历了多轮的结构重组：（1）M期晚期向G1期过渡时，核仁形成，形成FC、DFC和GCs，从而形成三重核仁：（2）G1期中期FC/DFC被破坏，三重核仁逐渐变为二重核仁;（3）在G1晚期，FC/DFC的重组导致二分核仁向三分核仁的结构转变：（4）随着细胞进入S期，FC/DFC再次解体，三分核仁变为二分核仁。值得注意的是，FC/DFC直到S期晚期才被观察到;（5）FC/DFC在G2期间经历结构破坏和恢复，以及（6）当细胞处于有丝分裂阶段时，FC/DFC在核仁结构解体之前消失。这些结果还表明，在高等真核生物的细胞周期的某些时期，二分核仁也可能存在。由于结构是多种细胞活动的根本基础，揭示核仁FC和DFC的结构重组可能会带来对相关细胞功能时空区室化的见解。
Nucleolus structure alters as the cell cycle is progressing. It is established in telophase, maintained throughout the entire interphase and disassembled in metaphase. Fibrillar centers (FCs), dense fibrillar components (DFCs) and granular components (GCs) are essential nucleolar organizations where rRNA transcription and processing and ribosome assembly take place. Hitherto, little is known about the cell cycle-dependent reorganization of these structures. In this study, we followed the nucleolus structure during the cell cycle by electron microscopy (EM). We found the nucleolus experienced multiple rounds of structural reorganization within a single cell cycle: (1) when nucleoli are formed during the transition from late M to G1 phase, FCs, DFCs and GCs are constructed, leading to the establishment of tripartite nucleolus; (2) as FC/DFCs are disrupted at mid-G1, tripartite nucleolus is gradually changed into a bipartite organization; (3) at late G1, the reassembly of FC/DFCs results in a structural transition from bipartite nucleolus towards tripartite nucleolus; (4) as cells enter S phase, FC/DFCs are disassembled again and tripartite nucleolus is thus changed into a bipartite organization. Of note, FC/DFCs were not observed until late S phase; (5) FC/DFCs experience structural disruption and restoration during G2 and (6) when cells are at mitotic stage, FC/DFCs disappear before nucleolus structure is disassembled. These results also suggest that bipartite nucleolus can exist in higher eukaryotes at certain period of the cell cycle. As structures are the fundamental basis of diverse cell activities, unveiling the structural reorganization of nucleolar FCs and DFCs may bring insights into the spatial–temporal compartmentalization of relevant cellular functions.