A novel function of Huntingtin in the cilium and retinal ciliopathy in Huntington's disease mice

Huntington's disease (HD) is a neurodegenerative disorder caused by the toxic expansion of polyglutamine in the Huntingtin (HTT) protein. The pathomechanism is complex and not fully understood. Increasing evidence indicates that the loss of normal protein function also contributes to the pathogenesis, pointing out the importance of understanding the physiological roles of HTT. We provide evidence for a novel function of HTT in the cilium. HTT localizes in diverse types of cilia — including 9 + 0 non-motile sensory cilia of neurons and 9 + 2 motile multicilia of trachea and ependymal cells — which exert various functions during tissue development and homeostasis. In the photoreceptor cilium,…