Cyclin B3 activates the Anaphase-Promoting Complex/Cyclosome in meiosis and mitosis

• DOI: 10.1371/journal.pgen.1009184
• Publication Date: 2020-11-02T18:44:48Z
• Authors: Damien Garrido; Mohammed Bourouh; Éric Bonneil; Pierre Thibault; Andrew Swan; Vincent Archambault
• Keywords: Anaphase-promoting complex; Cyclin B; Cyclin B1

In mitosis and meiosis, chromosome segregation is triggered by the Anaphase-Promoting Complex/Cyclosome (APC/C), a multi-subunit ubiquitin ligase that targets proteins for degradation, leading to separation of chromatids. APC/C activation requires phosphorylation its APC3 APC1 subunits, which allows bind co-activator Cdc20. The identity kinase(s) responsible in vivo unclear. Cyclin B3 (CycB3) an activator Cyclin-Dependent Kinase 1 (Cdk1) required meiotic anaphase flies, worms vertebrates. It has been hypothesized CycB3-Cdk1 may be meiosis but this remains determined. Using Drosophila, we found mutations CycB3 genetically enhance tws, encodes B55 regulatory subunit Protein Phosphatase 2A (PP2A) known promote mitotic exit. Females heterozygous tws loss-of-function alleles lay embryos arrest metaphase maternal effect, indicating promotes addition meiosis. This not due Spindle Assembly Checkpoint (SAC) because mutation mad2 inactivates SAC does rescue development from CycB3-/+, tws-/+ females. Moreover, activity cells culture. We show physically associates with APC/C, APC3, association Cdc20 co-activators Fizzy Cortex. Our results strongly suggest directly activates both mitosis.