Disease-Associated Mutations in CEP120 Destabilize the Protein and Impair Ciliogenesis

Publication date: 29 May 2018 Source:Cell Reports, Volume 23, Issue 9 Author(s): Nimesh Joseph, Caezar Al-Jassar, Christopher M. Johnson, Antonina Andreeva, Deepak D. Barnabas, Stefan M.V. Freund, Fanni Gergely, Mark van Breugel Ciliopathies are a group of genetic disorders caused by a failure to form functional cilia. Due to a lack of structural information, it is currently poorly understood how ciliopathic mutations affect protein functionality to give rise to the underlying disease. Using X-ray crystallography, we show that the ciliopathy-associated centriolar protein CEP120 contains three C2 domains. The point mutations V194A and A199P, which cause Joubert syndrome (JS) and Jeune asphyxiating thoracic dystrophy (JATD), respectively, both reduce the thermostability of the second C2 domain by targeting residues that point toward its hydrophobic core. Genome-engineered cells homozygous for these mutations have largely normal centriole numbers but show reduced CEP120 levels, compromised recruitment of distal centriole markers, and deficient cilia formation. Our results provide insight into the disease mechanism of two ciliopathic mutations in CEP120, identify putative binding partners of CEP120 C2B, and suggest a complex genotype-phenotype relation of the CEP120 ciliopathy alleles. Graphical abstract Teaser Joseph et al. structurally and functionally characterize a conserved C2 domain of the centriolar protein CEP120, which harbors two distinct ciliopathy-associat...

Source: Cell Reports - May 30, 2018 Category: Cytology Source Type: research