Identification of a novel KRIT1 interactor involved in the control of actin cytoskeleton dynamics.

The KRIT1 protein is involved in the Cerebral Cavernous Malformations (CCM) disease, which is mainly characterized by serious alterations of brain capillary architecture. KRIT1 contains multiple interaction domains and motifs, suggesting that it might act as a scaffold for the assembly of functional protein complexes involved in signalling networks. Using the yeast two-hybrid (Y2H) technology, we identified a novel molecular interactor of KRIT1, named C17. The novel interaction was confirmed by pull-down assays as well as by co-immunoprecipitation experiments in human endothelial cells. Furthermore, using distinct KRIT1 mutated constructs, we defined the contribute of the different KRIT1 domains to the C17/KRIT1 interaction. Finally, fluorescence microscopy experiments showed a significant co-localization of C17 and KRIT1 within the cytoplasm, and suggested that C17 may influence the KRIT1 nucleocytoplasmic shuttling. As both C17 and KRIT1 has been involved in actin cytoskeleton dynamics and cellular responses to oxidative stress, the novel identified C17/KRIT1 interaction provides new and useful insights into the understanding of the molecular mechanisms underlying CCM pathogenesis.