Cep192: An essential protein for centrosomal microtubule nucleation
O'Rourke, Brian Patrick
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Centrosomal protein of 192 kDa (Cep192) is a basal scaffolding protein of the pericentriolar material. Cep 192 has been shown to be an important regulator of microtubule (MT) nucleation during mitosis, responsible for the recruitment of known MT nucleating proteins including gamma-tubulin. While most prominent in mitosis, the centrosome remains present in interphase where it is known to play important roles in cell signaling, shape, and differentiation. Here we show that Cep192 also positively regulates MT nucleation capacity at the centrosome during interphase and is essential for the centrosomal localization of many other proteins. Interestingly, while Cep192 co-recruits Pericentrin in mitosis, during interphase Cep192 limits Pericentrin levels at the centrosome, and vice-versa. Additionally, following the loss of Cep192, MT nucleation increases at sites outside of the centrosome, most notably at the Golgi apparatus. This shift in MT nucleation site alters the organization and characteristics of the MT array (decreasing in MT dynamics and increasing in tubulin acetylation) impacting downstream processes including both 2D and 3D cell migration. Using a novel nanoparticle encapsulation of siRNA, we also show that Cep192 also plays a role in proper angiogenesis of fetal heart explants as Cep192 depleted hearts are unable to form vessels. Based on these data we propose that Cep192 is essential for maintaining the centrosomal subpopulation of MTs required for normal cellular function. Finally, we show that MT end binding drug eribulin disrupts plus-end binding complex formation and has a downstream impact on MT dynamics and cell migration.