Aurora B kinase phosphorylates keratin 8 at the cleavage furrow to drive spatially restricted intermediate filament disassembly during cytokinesis.

Keratins form intermediate filament networks that stabilize epithelial cells and many cancer cells. During cytokinesis, these filaments must be locally disassembled at the cleavage furrow to allow furrow ingression and cell separation. In this issue, Harmanda et al. demonstrate that Aurora B kinase directly phosphorylates Keratin 8 at multiple sites, with pS34-K8 being highly enriched specifically at the contractile ring and the midzone. Using in vitro kinase assays, mass spectrometry, phospho-specific antibodies, CRISPR Keratin 8 knockout, and non-phosphorylatable/phosphomimetic mutants, the authors show that Aurora B-mediated phosphorylation promotes keratin filaments disassembly at the furrow. Noticeably, Keratin 8 scaffolds Aurora B to the midzone, creating a positive feedback loop that is essential for cytokinesis in epithelial cancer cells. These data reveal a novel, spatially regulated mechanism linking Aurora B to intermediate filament dynamics and highlight potential therapeutic opportunities in carcinomas that overexpress Keratin 8.