The retromer complex regulates C. elegans development and mammalian ciliogenesis

The mammalian retromer is comprised of subunits VPS26, VPS29 and VPS35, and a more loosely-associated sorting nexin (SNX) heterodimer. Despite known roles for the retromer in multiple trafficking events in yeast and mammalian cells, its role in development is poorly understood, and its potential function in primary ciliogenesis remains unknown. Using CRISPR-Cas9 editing, we demonstrated that vps-26 homozygous knockout C. elegans have reduced brood sizes and impaired vulval development, as well as decreased body length which has been linked to defects in primary ciliogenesis. Since many endocytic proteins are implicated in the generation of primary cilia, we addressed whether the retromer regulates ciliogenesis in mammalian cells. We observed VPS35 localized to the primary cilium, and depletion of VPS26, VPS35 or SNX1/SNX5 led to decreased ciliogenesis. Retromer also coimmunoprecipitated with the capping protein, CP110, and was required for its removal from the mother centriole. Herein, we characterize new roles for the retromer in C. elegans development and in the regulation of ciliogenesis in mammalian cells, and suggest a novel role for the retromer in CP110 removal from the mother centriole.