Dynamic changes in CCAN organization through CENP-C during cell-cycle progression.

The kinetochore is a crucial structure for faithful chromosome segregation during mitosis and is formed in the centromeric region of each chromosome. The 16-subunit protein complex known as the constitutive centromere-associated network (CCAN) forms the foundation for kinetochore assembly on the centromeric chromatin. Although the CCAN can be divided into several subcomplexes, it remains unclear how CCAN proteins are organized to form the functional kinetochore. In particular, this organization may vary as the cell cycle progresses. To address this, we analyzed the relationship of centromeric protein (CENP)-C with the CENP-H complex during progression of the cell cycle. We find that the middle portion of chicken CENP-C (CENP-C(166-324)) is sufficient for centromere localization during interphase, potentially through association with the CENP-L-N complex. The C-terminus of CENP-C (CENP-C(601-864)) is essential for centromere localization during mitosis, through binding to CENP-A nucleosomes, independent of the CENP-H complex. On the basis of these results, we propose that CCAN organization changes dynamically during progression of the cell cycle.