Disease Etiology and Structural Proteomics of Jbts17

PROJECT SUMMARY Craniofacial differences are caused by a large variety of genetic factors, and represent some of the most common inherited disorders in humans. Cilia are abundant eukaryotic organelles whose proper biogenesis and continued homeostasis are crucial to embryonic development and tissue function in vertebrates, greatly contributing to craniofacial morphology. Mutations that disrupt ciliogenesis prevent proper ciliary construction, beating, and signaling, resulting in a diverse array of birth defects and lifelong diseases. A protein complex called CPLANE is required at multiple steps of ciliogenesis, and disease-causing mutations in its constituent subunits have been identified in clinical settings. However, the disease etiology of Jbts17, the largest and most enigmatic CPLANE subunit, remains unknown. Here, I propose to study the molecular mechanism of action and interactions of Jbts17, which is clinically associated with the diseases Oral-Facial-Digital Syndrome, Joubert Syndrome, and Meckel-Gruber Syndrome. In Aim 1, I will use a vertebrate model organism to directly test the role of seven disease-associated Jbts17 variants in protein stability and localization to the basal body. I will also test their role in basal body migration to and docking at the plasma membrane, along with the recruitment of Intraflagellar Transport proteins. In Aim 2, I will further leverage these disease variants with preliminary computational results to identify the role of Jbts17 during Distal Appendage Vesicle recruitment and Ciliary Vesicle formation, two early steps in the process of ciliogenesis. Aim 3 will explore Jbts17 protein-protein interactions on an amino acid-level resolution using mass spectrometry-based proteomics. By determining the molecular mechanism and interactions of Jbts17, this work will add new depth to our understanding of Jbts17 disease-causing alleles in craniofacial ciliopathies. Furthermore, the proteomics experiments proposed here will potentially implicate new proteins in ciliogenesis and craniofacial morphology. Impact: Experiments proposed here will lead to an improved understanding of the genetics and cell biology of ciliogenesis and ciliary vesicle trafficking. The results will aid in diagnosing craniofacial genetic disease and will help lay the foundational knowledge for future development of therapies to restore tissue function in patients with ciliopathies.