Laura Bellutti, Nicolas Macaisne, Layla El Mossadeq, Thadshagine Ganeswaran, Julie C Canman, Julien Dumont
{"title":"Regulation of outer kinetochore assembly during meiosis I and II by CENP-A and KNL-2/M18BP1 in C. elegans oocytes.","authors":"Laura Bellutti, Nicolas Macaisne, Layla El Mossadeq, Thadshagine Ganeswaran, Julie C Canman, Julien Dumont","doi":"10.1016/j.cub.2024.09.004","DOIUrl":null,"url":null,"abstract":"<p><p>During cell division, chromosomes build kinetochores that attach to spindle microtubules. Kinetochores usually form at the centromeres, which contain CENP-A nucleosomes. The outer kinetochore, which is the core attachment site for microtubules, is composed of the KMN network (Knl1c, Mis12c, and Ndc80c complexes) and is recruited downstream of CENP-A and its partner CENP-C. In C. elegans oocytes, kinetochores have been suggested to form independently of CENP-A nucleosomes. Yet kinetochore formation requires CENP-C, which acts in parallel to the nucleoporin MEL-28<sup>ELYS</sup>. Here, we used a combination of RNAi and Degron-based depletion of CENP-A (or downstream CENP-C) to demonstrate that both proteins are in fact responsible for a portion of outer kinetochore assembly during meiosis I and are essential for accurate chromosome segregation. The remaining part requires the coordinated action of KNL-2 (ortholog of human M18BP1) and of the nucleoporin MEL-28<sup>ELYS</sup>. Accordingly, co-depletion of CENP-A (or CENP-C) and KNL-2<sup>M18BP1</sup> (or MEL-28<sup>ELYS</sup>) prevented outer kinetochore assembly in oocytes during meiosis I. We further found that KNL-2<sup>M18BP1</sup> and MEL-28<sup>ELYS</sup> are interdependent for kinetochore localization. Using engineered mutants, we demonstrated that KNL-2<sup>M18BP1</sup> recruits MEL-28<sup>ELYS</sup> at meiotic kinetochores through a specific N-terminal domain, independently of its canonical CENP-A loading factor activity. Finally, we found that meiosis II outer kinetochore assembly was solely dependent on the canonical CENP-A/CENP-C pathway. Thus, like in most cells, outer kinetochore assembly in C. elegans oocytes depends on centromeric chromatin. However, during meiosis I, an additional KNL-2<sup>M18BP1</sup> and MEL-28<sup>ELYS</sup> pathway acts in a non-redundant manner and in parallel to canonical centromeric chromatin.</p>","PeriodicalId":11359,"journal":{"name":"Current Biology","volume":null,"pages":null},"PeriodicalIF":8.1000,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11537844/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Current Biology","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1016/j.cub.2024.09.004","RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/9/30 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
During cell division, chromosomes build kinetochores that attach to spindle microtubules. Kinetochores usually form at the centromeres, which contain CENP-A nucleosomes. The outer kinetochore, which is the core attachment site for microtubules, is composed of the KMN network (Knl1c, Mis12c, and Ndc80c complexes) and is recruited downstream of CENP-A and its partner CENP-C. In C. elegans oocytes, kinetochores have been suggested to form independently of CENP-A nucleosomes. Yet kinetochore formation requires CENP-C, which acts in parallel to the nucleoporin MEL-28ELYS. Here, we used a combination of RNAi and Degron-based depletion of CENP-A (or downstream CENP-C) to demonstrate that both proteins are in fact responsible for a portion of outer kinetochore assembly during meiosis I and are essential for accurate chromosome segregation. The remaining part requires the coordinated action of KNL-2 (ortholog of human M18BP1) and of the nucleoporin MEL-28ELYS. Accordingly, co-depletion of CENP-A (or CENP-C) and KNL-2M18BP1 (or MEL-28ELYS) prevented outer kinetochore assembly in oocytes during meiosis I. We further found that KNL-2M18BP1 and MEL-28ELYS are interdependent for kinetochore localization. Using engineered mutants, we demonstrated that KNL-2M18BP1 recruits MEL-28ELYS at meiotic kinetochores through a specific N-terminal domain, independently of its canonical CENP-A loading factor activity. Finally, we found that meiosis II outer kinetochore assembly was solely dependent on the canonical CENP-A/CENP-C pathway. Thus, like in most cells, outer kinetochore assembly in C. elegans oocytes depends on centromeric chromatin. However, during meiosis I, an additional KNL-2M18BP1 and MEL-28ELYS pathway acts in a non-redundant manner and in parallel to canonical centromeric chromatin.
期刊介绍:
Current Biology is a comprehensive journal that showcases original research in various disciplines of biology. It provides a platform for scientists to disseminate their groundbreaking findings and promotes interdisciplinary communication. The journal publishes articles of general interest, encompassing diverse fields of biology. Moreover, it offers accessible editorial pieces that are specifically designed to enlighten non-specialist readers.