Research Overview

Fig 1: Analysis of CENP gene expression in the cell cycle indicates that a small number of genes are temporally regulated. This suggests that a few key proteins may be driving the temporal organization of centromere replication.

Fig 2: Methods for conditional labeling of protein populations, SNAP tag technology, permits direct analysis of the heritability of proteins across multiple cell cycles.

Successful passage of cellular generation requires the replication of the chromosomes and their segregation into new daughter cells. The centromere directs the segregation process during mitosis by assembling the kinetochore which both powers chromosme movement and regulates the progress of mitosis. Centromeres, however, are not directly specified by DNA sequence but rather through a unique chromatin configuration based on the centromere-specific histone H3 variant CENP-A.

How is a chromatin-based locus replicated with high fidelity in each cell cycle? We are studying the basis of chromatin-directed inheritance in human cells by dissecting the pathway for centromere assembly in human cells. Efforts are focused on understanding the regulation of an ensemble of ~15 genes coding for CENP-A and a number of other constitutive CENPs, identifying which of those proteins are heritable in situ and when they are assembled.

Linking centromere function to the mechanism of assembly is thought to be a key to errorproof epigenetic replication of this locus. Biochemical analysis of centromere replication intermediates and investigation of how mitotic events, particularly checkpoint activities, influence the assembly pathway are key goals of the laboratory.