The X-linked Deubiquitinase USP9X Is an Integral Component of Centrosome

Abstract The X-linked deubiquitinase USP9X has been implicated in multiple pathological disorders including malignancies and X-linked intellectual disability. However, its biological function and substrate repertoire remain to be investigated. In this study, we utilized the TMT (tandem mass tags) labeling assay to identify USP9X regulated proteins, and revealed that the expression of multiple genes is altered in USP9X deficient cells. Interestingly, we showed that USP9X promotes stabilization of centrosome protein PCM1 and CEP55 through its catalytic activity. Remarkably, we demonstrated that USP9X is physically associated and spatially co-localized with PCM1 and CEP55 in centrosome, and we revealed that either PCM1 or CEP55 loss resulted in impairment of USP9X centrosome localization. Moreover, we showed that USP9X is required for centrosome duplication and this effect is dependent on its catalytic activity and its N-terminal module, which is responsible for physical association of USP9X with PCM1 and CEP55. Collectively, our experiments identified USP9X as an integral component of centrosome, where it functions to stabilize PCM1 and CEP55 and promotes centrosome biogenesis.