ACS DIVISION OF BIOLOGICAL CHEMISTRY

April 3rd, 2014 by Gudi, R., Zou, C., Dhar, J., Gao, Q., Vasu, C.

Centriole duplication is the process by which two new daughter centrioles are generated from the proximal end of pre-existing mother centrioles. Accurate centriole duplication is important for many cellular and physiological events including cell division and ciliogenesis. Centrosomal protein 4.1-associated protein (CPAP), centrosomal protein of 152 kDa (CEP152) and centrobin are known to be essential for centriole duplication. However, the precise mechanism by which they contribute to centriole duplication is not known. In this study, we show that centrobin interacts with CEP152 and CPAP and the centrobin-CPAP interaction is critical for centriole duplication. While depletion of centrobin from cells did not have an effect on the centriolar levels of CEP152, it caused the disappearance of CPAP from both the pre-existing and newly formed centrioles. Moreover, exogenous expression of the CPAP-binding fragment of centrobin also caused disappearance of CPAP from both the pre-existing and newly synthesized centrioles, possibly in a dominant negative manner, thereby inhibiting centriole duplication and the PLK4-overexpression mediated centrosome amplification. Interestingly, exogenous overexpression of CPAP in the centrobin-depleted cells did not restore CPAP localization to the centrioles. However, restoration of centrobin expression in the centrobin-depleted cells led to reappearance of centriolar CPAP. Hence, we conclude that centrobin-CPAP interaction is critical for the recruitment of CPAP to pro-centrioles to promote the elongation of daughter centrioles, and for the persistence of CPAP on pre-existing mother centrioles. Our study indicates that regulation of CPAP levels on the centrioles by centrobin is critical for preserving the normal size, shape, and number of centrioles in the cell.