A huntingtin-HAP1-PCM1 pathway in ciliogenesis.

Huntington's disease (HD) is caused by expansion of a polyglutamine repeat in the N-terminal region of huntingtin (htt), a large protein that has been found to interact with a variety of proteins. It remains to be determined how the interactions of htt with other proteins are involved in the pathogenesis of HD. A recent publication by Keryer et al. demonstrates that htt regulates ciliogenesis by interacting with PCM1 through HAP1. This recent study shows that htt and HAP1 are essential for protein trafficking to the centrosome, as well as normal ciliogenesis, and that mutant htt causes abnormal ciliogenesis, providing a novel insight into the pathogenesis of HD.