The spindle pole body of Schizosaccharomyces pombe enters and leaves the nuclear envelope as the cell cycle proceeds
The spindle pole body of Schizosaccharomyces pombe enters and leaves the nuclear envelope as the cell cycle proceeds
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DOI：
10.1091/mbc.8.8.1461
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发表时间：
1997-08-01
影响因子：
3.3
通讯作者：
McIntosh, JR
中科院分区：
文献类型：
--
作者：
Ding, R;West, RR;McIntosh, JR
粟酒裂殖酵母中纺锤体极体（SPB）复制、分化和分离的周期与其他一些酵母不同。与脊椎动物细胞的中心体一样，粟酒裂殖酵母的 SPB 大部分间期都在细胞质中，紧邻核膜。一些 γ-微管蛋白位于 SPB 上，表明它在间期微管 (MT) 的组织中发挥作用，并且连续切片表明一些间期 MT 终止于 SPB 上或非常靠近 SPB。 γ-微管蛋白也存在于核膜内表面附近、紧邻 SPB 的嗜锇物质上，尽管间期核中没有 MT。显然，粟酒裂殖酵母中γ-微管蛋白的MT启动活性受到调节。 SPB 在 G(2) 期晚期在细胞质中复制，所得的两个结构通过深色染色桥连接，直到有丝分裂纺锤体形成。当细胞进入有丝分裂时，核膜在 SPB 旁边内陷，形成一个细胞质袋，积累黑色无定形物质。然后核膜打开形成一个窗孔，复制的 SPB 就进入其中。 SPB 的每个部分都会启动核内 MT，然后两个结构分开，以双极纺锤体的形式位于不同的窗孔中。通过中期，SPB 仍保留在其窗孔中，与纺锤体 MT 的极端结合；大约在此时，与每个 SPB 相关的一小束细胞质 MT 形成。这些 MT 的一端靠近 SPB，但不在 SPB 上，并且它们以与纺锤体轴倾斜的方向投射到细胞质中。随着后期的进行，核窗关闭，SPB 被挤出回到细胞质中。这些观察结果定义了有关 SPB 复制控制和核膜动力学的新研究领域。
The cycle of spindle pole body (SPB) duplication, differentiation, and segregation in Schizosaccharomyces pombe is different from that in some other yeasts. Like the centrosome of vertebrate cells, the SPB of S. pombe spends most of interphase in the cytoplasm, immediately next to the nuclear envelope. Some gamma-tubulin is localized on the SPB, suggesting that it plays a role in the organization of interphase microtubules (MTs), and serial sections demonstrate that some interphase MTs end on or very near to the SPB. gamma-Tubulin is also found on osmiophilic material that lies near the inner surface of the nuclear envelope, immediately adjacent to the SPB, even though there are no MTs in the interphase nucleus. Apparently, the MT initiation activities of gamma-tubulin in S. pombe are regulated. The SPB duplicates in the cytoplasm during late G(2) phase, and the two resulting structures are connected by a darkly staining bridge until the mitotic spindle forms. As the cell enters mitosis, the nuclear envelope invaginates beside the SPB, forming a pocket of cytoplasm that accumulates dark amorphous material. The nuclear envelope then opens to form a fenestra, and the duplicated SPB settles into it. Each part of the SPB initiates intranuclear MTs, and then the two structures separate to lie in distinct fenestrae as a bipolar spindle forms. Through metaphase, the SPBs remain in their fenestrae, bound to the polar ends of spindle MTs; at about this time, a small bundle of cytoplasmic MTs forms in association with each SPB. These MTs are situated with one end near to, but not on, the SPBs, and they project into the cytoplasm at an orientation that is oblique to the spindle axis. As anaphase proceeds, the nuclear fenestrae close, and the SPBs are extruded back into the cytoplasm. These observations define new fields of enquiry about the control of SPB duplication and the dynamics of the nuclear envelope.