Inhibition of protein deacetylation by trichostatin A impairs microtubule-kinetochore attachment

Inhibition of protein deacetylation arrests cells in mitosis, but the mechanism is unknown. To understand why inhibiting protein deacetylation causes cell cycle arrest, we treated HeLa cells beyond G1/S transition with trichostatin A (TSA), a potent protein deacetylase inhibitor, and found that the cells arrested at prometaphase with ectopic spindles and unaligned chromosomes. The hyper-acetylated cells encountered a serious microtubule (MT)-kinetochore attachment problem, although the kinetochores are intact at ultrastructural level. By immunofluorescence staining of kinetochore proteins, we found that the pericentromeric H3K9Me3-HP1 pathway was disrupted and that the CENP-A-dependent outer plate protein dynamics of kinetochores was greatly diminished by the drug treatment. The treatment also caused the loss of chromosome passenger complex (CPC), the proposed error checking system, from centromere and impaired the microtubule dynamics of the cells. Overall, we propose that deacetylation inhibition impairs MT-kinetochore attachment through disrupting the centromere function and altering the kinetochore composition and MT dynamics.