The disassembly of integrin-containing focal adhesions (FAs) at mitotic entry is essential for cell rounding, mitotic retraction fibre formation, bipolar spindle positioning and chromosome segregation. The mechanism that drives FA disassembly at mitotic entry is unknown. Here, we show that the CDK1–cyclin B1 complex phosphorylates the integrin activator kindlin, which results in the recruitment of the cullin 9–FBXL10 ubiquitin ligase complex that mediates kindlin ubiquitination and degradation. This molecular pathway is essential for FA disassembly and cell rounding, as phospho-inhibitory mutations of the CDK1 motif prevent kindlin degradation, FA disassembly and mitotic cell rounding. Conversely, phospho-mimetic mutations promote kindlin degradation in interphase, accelerate mitotic cell rounding and impair mitotic retraction fibre formation. Despite the opposing effects on kindlin stability, both types of mutations cause severe mitotic spindle defects, apoptosis and aneuploidy. Thus, the exquisite regulation of kindlin levels at mitotic entry is essential for cells to progress accurately through mitosis.

在有丝分裂进入时含有整合素的粘着斑 (FAs) 的拆卸对于细胞圆化、有丝分裂回缩纤维形成、双极纺锤体定位和染色体分离至关重要。在有丝分裂进入时驱动 FA 分解的机制尚不清楚。在这里，我们发现 CDK1-cyclin B1 复合物磷酸化整合素激活剂 kindlin，这导致 cullin 9-FBXL10 泛素连接酶复合物的募集，该复合物介导 kindlin 泛素化和降解。该分子途径对于 FA 分解和细胞变圆至关重要，因为 CDK1 基序的磷酸抑制突变可防止 kindlin 降解、FA 分解和有丝分裂细胞变圆。相反，磷酸模拟突变促进间期的 kindlin 降解，加速有丝分裂细胞变圆并损害有丝分裂回缩纤维的形成。尽管对 kindlin 稳定性有相反的影响，但这两种类型的突变都会导致严重的有丝分裂纺锤体缺陷、细胞凋亡和非整倍性。因此，在有丝分裂进入时对 kindlin 水平的精细调节对于细胞准确地通过有丝分裂至关重要。