3-D FINE STRUCTURE OF THE C ELEGANS MEIOTIC SPINDLE POLE

线虫减数分裂纺锤体的 3-D 精细结构

• 批准号: 7354990
• 负责人: THOMAS MULLER-REICHERT
• 金额: $ 1.41万
• 依托单位: UNIVERSITY OF COLORADO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-26 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7354990
• 关键词: Caenorhabditis elegans; cell cycle; centrosome; chromatin; cytoplasm; gene mutation; genes; meiosis; mitotic spindle apparatus; proteins

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Faithful chromosome segregation during meiosis and mitosis depends on assembly of the microtubules (MTs) into a bipolar spindle. The meiotic spindle of the C. elegans ovum is morphologically distinct from the first mitotic spindle of the zygote, yet both structures form in the same cytoplasm approximately 20 minutes apart. Instead of nucleating from centrosomes as in mitosis, meiotic MTs polymerize initially around chromatin. Chromatin-associated plus-end directed motor proteins have been implicated in pushing MT minus ends away from the chromatin, and the MT array is then focused into two opposing poles. Recently the mei-1 and mei-2 genes of C. elegans were found to be required for meiotic spindle formation but not for mitotic spindle function. Genetic analysis has shown that mei-1 and mei-2 genes are the katanin orthologues in C. elegans. Katanin is a heterodimeric MT-severing protein consisting of a catalytic and a regulatory subunit. Loss-of-function mutations result in disorganized meiotic spindles and meiotic failure, but the subsequent mitotic spindles are normal. In contrast, gain-of-function mutations result in normal meiosis followed by mitosis on short spindles. These observations suggest that the MT severing activity of katanin may explain how meiotic spindles maintain their small size in a cytoplasm environment that later supports the assembly of a much larger mitotic spindle. We have produced serial tomograms from two female meiotic spindles and found that the majority (~80%) of the pole-proximal MT ends are open, in contrast to the closed/capped ends that predominate at the centrosome of the mitotic spindle. We are currently preparing strains with gain and loss-of-function mutations in mei-1 to determine how the 3D arrangements and morphology of MTs are affected by the function of katanin-like proteins during meiosis.

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。在减数分裂和有丝分裂过程中，忠实的染色体分离依赖于微管（mt）组装成双极纺锤体。秀丽隐杆线虫卵的减数分裂纺锤体在形态上与合子的第一个有丝分裂纺锤体不同，但两者的结构形成于相同的细胞质中，间隔约20分钟。减数分裂mt最初在染色质周围聚合，而不是像有丝分裂那样从中心体成核。染色质相关的正端定向马达蛋白参与将MT负端推离染色质，然后MT阵列聚焦成两个相反的极点。最近发现秀丽隐杆线虫的mei-1和mei-2基因是减数分裂纺锤体形成所必需的，而不是有丝分裂纺锤体功能所必需的。遗传分析表明，秀丽隐杆线虫的mei-1和mei-2基因是katanin同源基因。Katanin是一种异二聚体mt切断蛋白，由催化亚基和调节亚基组成。功能丧失突变导致减数分裂纺锤体紊乱和减数分裂失败，但随后的有丝分裂纺锤体是正常的。相反，功能获得突变导致正常的减数分裂，随后是短纺锤体的有丝分裂。这些观察结果表明，katanin的MT切断活性可能解释了减数分裂纺锤体如何在细胞质环境中保持其小尺寸，而细胞质环境后来支持更大的有丝分裂纺锤体的组装。我们对两个雌性减数分裂纺锤体进行了连续断层扫描，发现大多数（~80%）的极近端MT端是开放的，而有丝分裂纺锤体的中心体主要是封闭/帽端。我们目前正在制备具有mei-1功能获得和功能丧失突变的菌株，以确定减数分裂期间角质蛋白样蛋白的功能如何影响mt的3D排列和形态。