The Kinetochore Biology Diagrams Faithful chromosome segregation during mitosis depends on the bi-oriented attachment of chromosomes to spindle microtubules through their kinetochores. The precise regulation of kinetochore When the chromosome becomes properly attached to the mitotic spindle, microtubules of the spindle physically compete for binding to the same site on the kinetochore where MPS1 is bound. Thus, once the kinetochore is properly attached, MPS1 dissociates, the inhibitory signal is lost, and cell division is allowed to proceed.
The kinetochore establishes the linkage between chromosomes and the spindle microtubule plus ends during mitosis. In vertebrates, the spindle-kinetochore-associated (Ska1,2,3) complex stabilizes kinetochore attachment with the microtubule plus ends, but how Ska is recruited to and stabilized at the kinetochore-microtubule interface is not understood. In this way, RZZ-mediated inhibition of Ndc80 likely prevents the formation of stable end-on attachments early in mitosis when there is a high frequency of incorrect kinetochore-microtubule interactions (Cheerambathur et al., 2013), such as syntelic attachments - where both sister kinetochores are attached to the same pole or merotelic Merotelic kinetochore attachment represents a serious threat for dividing cells because it frequently occurs in the early stages of mitosis , it does not trigger SAC-dependent arrest in mitosis and uncorrected merotelically attached kinetochores can lead to chromosome mis-segregation and aneuploidy [2,3,20,36,37]. Therefore, mechanisms
Kinetochore Microtubule Dynamics and Attachment Stability Are Regulated ... Biology Diagrams
The impact of kinetochore-microtubule attachments on the composition and activity of Aurora B complexes at inner centromeres has not been established . It would also be important to determine whether Aurora B and INCENP turnover at inner centromeres is dependent on attachment status. Given that the activity of kinetochore-associated mitotic The Ndc80 complex may also have a key role in preventing chromosome missegregation by releasing improperly attached MTs from kinetochores. Merotelic kinetochore attachment (in which a kinetochore is attached to MTs emanating from both spindle poles) is a major cause of anaphase lagging chromosomes and aneuploidy in mammalian tissue cells (Cimini et al., 2001).
The combined effect of this phosphorylation eliminates incorrect kinetochore-microtubule attachments, resetting the kinetochore to an unattached ground state from which new, correct attachments can be formed. Importantly, it is critical that this correction mechanism target improper attachments without affecting bi-oriented kinetochores.
