Mapping the ciliary interactome, an extensive protein interaction network underlying human ciliopathies

SUMMARY Cilia are essential organelles, with functions ranging from cell-cell signaling to the generation of homeostatic fluid flow in tubular organs. Consequently, an array of human congenital diseases has been characterized as “ciliopathies,” because they share an etiology of defective cilia structure or function. Despite clear roles in the development of the central nervous system, limbs, axial skeleton, kidneys, airway, brain, and reproductive tracts, our understanding of the mechanisms that govern ciliogenesis and cilia-mediated developmental patterning remain incomplete, not least because hundreds of different proteins are required for proper cilia biogenesis and function, acting via an extensive interaction network containing diverse proteins of unknown function. We propose here to study several large multi-protein assemblies that are essential for proper cilia formation in order to determine the roles of these complexes in key steps in ciliogenesis, including recruitment of proteins to the basal body, intraflagellar transport and recruitment of specific intraflagellar cargoes. This grant combines directed mechanistic experiments, proteomics, 3D modeling, in vivo cell biology, and testing of human disease alleles in model organisms to understand mechanisms by which key ciliary proteins and their interaction partners effect proper cilia formation, and how specific mutations in these genes lead to birth defects. By focusing on proteins with demonstrated importance in development and disease, but for which no mechanism of action is yet known, experiments proposed here will provide important new breadth and depth to our understanding cilia-mediated developmental patterning and novel cell processes in ciliary biology. In turn, these findings should provide greater insight to a range of congenital diseases ranging from the relatively mild Oral-Facial-Digital syndrome to the wholly lethal Short Rib Polydactyly.