The regulatory mechanism of centrosome function is crucial to the accurate transmission of chromosomes to the daughter cells in mitosis. Recent findings on the post-translational modifications of many centrosomal proteins, led us to speculate that these modifications might be involved in centrosome behavior. Poly(ADP-ribose) polymerase-1 (PARP-1) catalyzes poly(ADP-ribosyl)ation to various proteins. Here, we show that PARP-1 localizes to centrosomes [1], and catalyzes poly(ADP-ribosyl)ation of centrosomal proteins [2]. Moreover, centrosome hyperamplification is frequently observed with PARP inhibitor as well as in PARP-1-null cells [2]. Thus, it is possible that chromosomal instability known in PARP-1-null cells is attributed to the centrosomal dysfunction. P53 tumor suppressor protein has been also shown to be localized at centrosomes, and to be involved in the regulation of centrosome duplication and monitoring of the chromosomal stability. We found that centrosomal p53 is poly(ADP-ribosyl)ated in vivo and centrosomal PARP-1 directly catalyzes poly(ADP-ribosyl)ation of p53 in vitro [2]. These results indicate that PARP-1 and PARP-1-mediated poly(ADP-ribosyl)ation of centrosomal proteins are involved in the regulation of centrosome function. References: 1.Kanai M et al: Biochem Biophys Res Commun, 2000; 278: 385-389 2.Kanai M et al: Mol Cell Biol, in press

Keywords: Centrosome, PARP-1, inhibitor, p53