Hamster chromosomes containing amplified human α-satellite DNA show delayed sister chromatid separation in the absence of de novo kinetochore formation

Abstract.

The centromeres of human chromosomes contain large amounts of the tandemly repeated α-satellite DNA family. Previous studies have shown that integration of α-satellite DNA into ectopic locations in mammalian chromosomes can result in the de novo formation of several features of centromeric function. Here we further examine the possible centromeric properties of α-satellite DNA by introducing it into hamster chromosomes. A large amplified region of ectopic α-satellite DNA was shown to direct binding of anticentromere antibodies (ACAs) and centromere protein B (CENP-B). The chromosome containing these ectopic arrays showed a high frequency of formation of anaphase bridges. Owing to the favourable morphology of these chromosomes, we were able to determine that this bridging was due to delayed sister chromatid disjunction at the location of the ectopic α-satellite, and not due to de novo formation of a fully functional kinetochore. A separate hamster cell line containing large tandemly repeated amplicons including the DHFR gene also displayed similar behaviour during anaphase. These results may support a role for α-satellite DNA in sister chromatid cohesion at centromeres. However, other repetitive DNA in favourable configurations appears to be capable of mimicking this behaviour during anaphase.