INJECTION OF ANTICENTROMERE ANTIBODIES IN INTERPHASE DISRUPTS EVENTS REQUIRED FOR CHROMOSOME MOVEMENT AT MITOSIS

We have used autoantibodies to probe the function of three human centromere proteins in mitosis. These antibodies recognize three human polypeptides in immunoblots: CENP-A (17 kD), CENP-B (80 kD), and CENP-C (140 kD). Purified anticentromere antibodies (ACA-IgG) disrupts mitosis when introduced into tissue culture cells during interphase. We have identified two execution points for antibody inhibition. Antibodies injected into the nucleus ≥3 h before mitosis prevent the chromosomes from undergoing normal prometaphase movements in the subsequent mitosis. Antibodies injected in the nucleus during late G2 cause cells to arrest in metaphase. Surprisingly, antibodies introduced subsequent to the beginning of prophase do not block mitosis. These results suggest that the CENP antigens are involved in two essential interphase events that are required for centromere action in mitosis. These may include centromere assembly coordinate with the replication of α-satellite DNA at the end of S phase and the structural maturation of the kinetochore that begins at prophase.