Mitotic spindle disassembly in human cells relies on CRIPT-bearing hierarchical redox signals

Swift and complete spindle disassembly is essential for cell survival, yet how it happens is largely unknown. Here we used real-time live-cell microscopy and biochemical assays to show that a cysteine-rich protein CRIPT dictates the spindle disassembly in a redox-dependent manner in human cells. This previously reported cytoplasmic protein was found to have a confined nuclear localization during interphase but was distributed to spindles and underwent redox modifications to form disulfides within CXXC pairs during mitosis. Then, it interacts with and transfers redox response to tubulin subunits to induce microtubule depolymerization. The mutants with any of cysteine substitution completely block the spindle disassembly generating two cell populations with long-lasting metaphase spindles or spindle remnants. The live cell recordings of a disease-relevant mutant (CRIPT C3Y ) revealed that microtubule depolymerization at spindle ends during anaphase and the entire spindle dissolution during telophase may share a common CRIPT-bearing redox-controlled mechanism.