Chromosomal instability Metaphase spreads were prepared at 72 h 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. 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.
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 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
A quantitative and semiautomated method for determining misaligned and ... Biology Diagrams
Downregulation of ERK2 leads to chromosome alignment defects.A, siRNA knockdown of ERK2. B, Compared with the overexpression of ERK2, overexpression of ERK2-2A led to a significant increase in cells with chromosome alignment defects in metaphase (ERK2 = 28.7 ± 4.4, p = 0.1438; ERK2-2A = 49.7 ± 3.0, p < 0.01;
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 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
Anaphase and Metaphase: Key Steps in Cell Division Biology Diagrams
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. 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
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
