Representative metaphases and common structural chromosome aberrations Biology Diagrams To determine chromosome alignment defects, cells were arrested in metaphase using approaches previously described in the literature (Kapoor et al., 2006; Fonseca and Stumpff, 2016). Briefly, cells were synchronized in mitosis using drugs that interfere with microtubule dynamics or formation of a bipolar spindle (such as nocodazole, or the Eg5 Intriguingly, FISH with chromosome-specific probes showed that, despite the defects resulting from KIF18A inactivation, there were no detectable alterations in chromosome copy number . Overall, these data suggest that although chromosome alignment prevents the formation of lagging chromosomes and micronuclei in anaphase, mechanisms exist that
Chromosome misalignments cause spindle misorientation. To study the role of Spindly in spindle positioning, we filmed cells grown on rectangular‐shaped micropatterns and measured the angle of the metaphase plate relative to the short cell axis (Fig (Fig1A). 1 A). Since Spindly depletion leads to chromosome alignment defects associated with a profound delay in mitosis (20 and Fig EV1 A), we
PAK2 is essential for chromosome alignment in metaphase I oocytes Biology Diagrams
(We defined misaligned chromosomes in metaphase as chromosomes that failed to align with the majority of chromosomes at metaphase plates.) (SD) from at least three independent experiments. For chromosome segregation defects, 100 mitotic cells were analyzed for each RNAi experiment. Scale bars in (C) and (D), 20 μm. Similar metaphase chromosome alignment defects were observed in cycled egg extracts (Figures S1A and S1C), in which sperm chromatin had undergone DNA replication and were arrested at the subsequent M phase. To strengthen these results in cycled egg extracts, we sought to inhibit the MRN activity through independent means by addition of a Understanding these phases highlights the mechanisms ensuring accurate chromosome segregation. Errors in these steps can lead to genetic abnormalities, making their regulation crucial for maintaining cellular integrity. Metaphase: Central Alignment. Metaphase is a pivotal stage where chromosomes align in preparation for segregation.
Defects in chromosome alignment are normally avoided by increased Aurora B activity at centromeres of misaligned chromosomes. 27 However, the correction of erroneous attachments underlying some chromosome alignment defects (e.g., syntelic attachments) appears to be less robust in cancer cells that also show overly stabilized kinetochore PAK2 is essential for chromosome alignment in metaphase I oocytes. The specific localization of PAK2 during oocyte maturation prompted us to ask whether Pak2 functions in the chromosome alignment The kinetochore, the protein complex assembled at the centromere of each mitotic chromosome, serves as the attachment site for the spindle MTs. A combination of forces generated by kinetochores and microtubule dynamics is thought to contribute to kinetochore-MT attachment and chromosome movement in achieving metaphase chromosome alignment.
