Differential requirement for centriolar satellites in cilium formation among different vertebrate cells

Centriolar satellites are ubiquitous in vertebrate cells. They have recently emerged as key regulators of centrosome/cilium biogenesis, and their mutations are linked to ciliopathies. However, their precise functions and mechanisms of action, which potentially differ between cell types, remain poorly understood. Here, we generated retinal pigmental and kidney epithelial cells lacking satellites by genetically ablating PCM1 to investigate their functions. While satellites were essential for cilium assembly in retinal epithelial cells, kidney epithelial cells lacking satellites still formed full-length cilia but at significantly lower levels, with reduced centrosomal levels of key ciliogenesis factors. Using these cells, we identified the first satellite-specific functions at cilia, specifically in regulating ciliary content, Hedgehog signalling, and epithelial cell organization. However, other satellite-linked functions, namely proliferation, cell cycle progression and centriole duplication, were unaffected in these cells. Quantitative transcriptomic and proteomic profiling revealed that loss of satellites scarcely affects transcription, but significantly alters the proteome, particularly actin cytoskeleton pathways and neuronal functions. Together, our findings identify cell type-specific roles for satellites and provide insight into the phenotypic heterogeneity of ciliopathies.