CRISPR/Cas9-mediated Genomic Editing of Cluap1/IFT38 Reveals a New Role in Actin Arrangement.

CRISPR/Cas9-mediated gene editing allows manipulation of a gene of interest in its own chromosomal context. When applied to the analysis of protein interactions and in contrast to exogenous expression of a protein, this can be studied maintaining physiological stoichiometry, topology, and context. We have used CRISPR/Cas9-mediated genomic editing to investigate Cluap1/IFT38, a component of the intraflagellar transport complex B (IFT-B). Cluap1 has been implicated in human development as well as in cancer progression. Cluap1 loss of function results in early developmental defects with neural tube closure, sonic hedgehog signaling and left-right defects. Herein, we generated an endogenously tagged Cluap1 for protein complex analysis, which was then correlated to the corresponding interactome determined by ectopic expression. Besides IFT-B complex components, new interacting proteins like Ephrin-B1 and TRIP6, which are known to be involved in cytoskeletal arrangement and protein transport, were identified. With the identification of platelet-derived growth factor A (PDGFA) and coiled-coil domain-containing protein 6 (CCDC6) two new interactions were discovered, which link Cluap1 to ciliogenesis and cancer development. The CRISPR/Cas9-mediated knockout of Cluap1 revealed a new phenotype affecting the actin cytoskeleton. Together, these data provide first evidence for a role of Cluap1 not only for cilia assembly and maintenance but also for cytoskeletal rearrangement and intracellular transport processes.