Kinetochore–microtubule interactions during cell division

Proper segregation of chromosomes during cell division is essential for the maintenance of genetic stability. During this process chromosomes must establish stable functional interactions with microtubules through the kinetochore, a specialized protein structure located on the surface of the centromeric heterochromatin. Stable attachment of kinetochores to a number of microtubules results in the formation of a kinetochore fibre that mediates chromosome movement. How the kinetochore fibre is formed and how chromosome motion is produced and regulated remain major questions in cell biology. Here we look at some of the history of research devoted to the study of kinetochore–microtubule interaction and attempt to identify significant advances in the knowledge of the basic processes. Ultrastructural work has provided substantial insights into the structure of the kinetochore and associated microtubules during different stages of mitosis. Also, recent in-vivo studies have probed deep into the dynamics of kinetochore-attached microtubules suggesting possible models for the way in which kinetochores harness the capacity of microtubules to do work and turn it into chromosome motion. Much of the research in recent years suggests that indeed multiple mechanisms are involved in both formation of the k-fibre and chromosome motion. Thus, rather than moving to a unified theory, it has become apparent that most cell types have the capacity to build the spindle using multiple and probably redundant mechanisms.