CENP-H, a constitutive centromere component, is required for centromere targeting of CENP-C in vertebrate cells

CENP-H has recently been discovered as a constitutive component of the cent romere that co-localizes with CENP-A and CENP-C throughout the cell cycle. The precise function, however, remains poorly understood. We examined the r ole of CENT-H in centromere function and assembly by generating a condition al loss-of-function mutant in the chicken DT40 cell line. In the absence of CENP-H, cell cycle arrest at metaphase, consistent with loss of centromere function, was observed. Immunocytochemical analysis of the CENP-H-deficien t cells demonstrated that CENP-H is necessary for CENP-C, but not CENP-A, l ocalization to the centromere. These findings indicate that centromere asse mbly in vertebrate cells proceeds in a hierarchical manner in which localiz ation of the centromere-specific histone CENP-A is an early event that occu rs independently of CENP-C and CENP-H.