CDK5-cyclin B1 regulates mitotic fidelity.

Zheng, Xiao-Feng; Sarkar, Aniruddha; Lotana, Humphrey; Syed, Aleem; Nguyen, Huy; Ivey, Richard G; Kennedy, Jacob J; Whiteaker, Jeffrey R et al. · Nature · 2024

basic_science · Level V

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Abstract

CDK1 has been known to be the sole cyclin-dependent kinase (CDK) partner of cyclin B1 to drive mitotic progression<sup>1</sup>. Here we demonstrate that CDK5 is active during mitosis and is necessary for maintaining mitotic fidelity. CDK5 is an atypical CDK owing to its high expression in post-mitotic neurons and activation by non-cyclin proteins p35 and p39<sup>2</sup>. Here, using independent chemical genetic approaches, we specifically abrogated CDK5 activity during mitosis, and observed mitotic defects, nuclear atypia and substantial alterations in the mitotic phosphoproteome. Notably, cyclin B1 is a mitotic co-factor of CDK5. Computational modelling, comparison with experimentally derived structures of CDK-cyclin complexes and validation with mutational analysis indicate that CDK5-cyclin B1 can form a functional complex. Disruption of the CDK5-cyclin B1 complex phenocopies CDK5 abrogation in mitosis. Together, our results demonstrate that cyclin B1 partners with both CDK5 and CDK1, and CDK5-cyclin B1 functions as a canonical CDK-cyclin complex to ensure mitotic fidelity.

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