Benavente R, Reimer G, Rose K M, Hügle-Dörr B, Scheer U
Institute of Zoology I, University of Würzburg, Federal Republic of Germany.
Chromosoma. 1988;97(2):115-23. doi: 10.1007/BF00327368.
After microinjection of antibodies against RNA polymerase I into the nuclei of cultured rat kangaroo (PtK2) and rat (RVF-SMC) cells alterations in nucleolar structure and composition were observed. These were detected by electron microscopy and double-label immunofluorescence microscopy using antibodies to proteins representative of the three major components of the nucleolus. The microinjected antibodies produced a progressive loss of the material of the dense fibrillar component (DFC) from the nucleoli which, at 4 h after injection, were transformed into bodies with purely granular component (GC) structure with attached fibrillar centers (FCs). Concomitantly, numerous extranucleolar aggregates appeared in the nucleoplasm which morphologically resembled fragments of the DFC and contained a protein (fibrillarin) diagnostic for this nucleolar structure. These observations indicate that the topological distribution of the material constituting the DFC can be experimentally influenced in interphase cells, apparently by modulating the transcriptional activity of the rRNA genes. These effects are different from nucleolar lesions induced by inhibitory drugs such as actinomycin D-dependent "nucleolar segregation". The structural alterations induced by antibodies to RNA polymerase I resemble, however, the initial events of nucleolar disintegration during mitotic prophase.
将抗RNA聚合酶I的抗体显微注射到培养的大鼠袋鼠（PtK2）和大鼠（RVF-SMC）细胞核中后，观察到核仁结构和组成的改变。通过电子显微镜以及使用针对代表核仁三大主要成分的蛋白质的抗体进行双标记免疫荧光显微镜检测到了这些改变。显微注射的抗体导致核仁中致密纤维成分（DFC）的物质逐渐丧失，在注射后4小时，核仁转变为具有附着纤维中心（FC）的纯颗粒成分（GC）结构的小体。与此同时，核质中出现了许多核仁外聚集体，其形态类似于DFC的片段，并含有一种对这种核仁结构具有诊断意义的蛋白质（纤维蛋白）。这些观察结果表明，构成DFC的物质的拓扑分布在间期细胞中可通过实验进行影响，显然是通过调节rRNA基因的转录活性。这些效应不同于放线菌素D等抑制药物诱导的核仁损伤，如依赖放线菌素D的“核仁分离”。然而，抗RNA聚合酶I抗体诱导的结构改变类似于有丝分裂前期核仁解体的初始事件。
