The role of the centriolar CEP350 network in centrobin removal from centrioles and distal appendage/CEP19 recruitment

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The centrosome is vital for cellular organization and division, and defects in its structure and function are linked to various human diseases. This proposal focuses on the centrosome protein CEP350 that is critical for controlling centriole length, stability, assembling subdistal (SDA) and distal (DA) appendages and centriole recruitment of CEP19. DA assembly and CEP19 recruitment are essential for ciliogenesis, and defects in their assembly are linked to various diseases such as ciliopathies and morbid obesity (CEP19). CEP350 also regulates the centriolar protein centrobin, which is necessary for proper centrosome function and is specifically removed from maturing centrioles by proteolysis. Dysregulation of centrobin removal is linked to Mulibrey nanism and cancer. Despite the importance of CEP350 for DA assembly, CEP19 recruitment and centrobin removal, its molecular functions are poorly understood. Understanding how CEP350 regulates these processes is critical for elucidating key open questions in centrosome biology and disease mechanisms and therefore stands in the focus of this proposal. Based on our preliminary findings, we propose that CEP350 is a multifunctional protein that cooperates with DISCO network components (several centriolar proteins needed together with CEP350 for DA assembly), DA proteins and CEP19 in order to achieve its functions. Our study, which combines the expertise of the laboratories of Profs. Pereira and Schiebel in centriole biology, CEP350 analysis, DA assembly and ciliogenesis, focuses on two major goals. Firstly, we aim to explore the detailed mechanisms of centrobin removal from centrioles by CEP350, SDAs, the E3 ligase TRIM37 and the by us newly identified kinase CRM5. In addition, we will also investigate whether centrobin removal is essential for DA assembly. Secondly, we will investigate how CEP350 interacting proteins and mother centriole specific modifications regulate DA assembly and CEP19 centriole recruitment at maturing centrioles. To achieve these goals, we will use various techniques, including gene knockouts, signal intensity measurements, super-resolution/expansion microscopy, electron microscopy, Minflux nanoscopy and mass spectrometry analysis of phosphorylation sites in a subset of CEP350 interacting proteins. By uncovering how CEP350 controls centrobin and DA assembly pathways, our study will help answering critical questions in centrosome biology, cilia assembly and how defects lead to disease.