C. elegans: An elegant experimental system for the study of cilia biology

Caenorhabditis elegans is a genetically tractable organism that has become one of the leading in vivo models for cilia research. Cilia are not required for viability in C. elegans, as only a subset of sensory neurons is ciliated in this organism. Yet, C. elegans cilia exhibit remarkable structural and functional diversity akin to their mammalian counterparts. Since the core mechanisms of cilia assembly are evolutionarily conserved, research in C. elegans has informed studies in other organisms on cilia biogenesis, trafficking, and functions and has provided key insights into mechanisms of cilia dysfunction in human disorders. Here, we provide a general overview of the C. elegans model for cilia research. Specifically, we review different cilia types and their underlying ultrastructural organization, discuss trafficking mechanisms for ciliary proteins, describe emerging functions of ciliary extracellular vesicles, and highlight a broad swathe of sophisticated tools available in C. elegans for studying multiple aspects of cilia biology.