Nannas explained that when cells divide, chromosomes must be equally split between the two cells. If mistakes occur, she said, some cells could receive too many or too few chromosomes. This condition is called aneuploidy, and it is associated with the development of tumors, accelerated cancer progression, miscarriages, and birth defects.
McVey, Cosby, and Nannas summarized the current state of research investigating how cells ensure equal splitting of chromosomes, specifically through a mechanism called the spindle checkpoint. This internal surveillance mechanism monitors chromosomes and measures the physical tension on them.
Chromosomes that are correctly aligned, Nannas said, and thus will pull apart properly, generate a tension force through a tug of war motion. A specific protein in the spindle checkpoint called Aurora B is the main observer of this tension, and there are currently several models that explain how Aurora B could measure tension on chromosomes.
The authors reviewed these models and analyzed their ability to explain all current data. They proposed new combinations of current models that form a more comprehensive understanding of this surveillance mechanism.