Dynamic disassembly and reconstruction of the nuclear lamina during entry and exit of mitosis, respectively, are pivotal steps in the proliferation of higher eukaryotic cells. Although numerous post-translational modifications of lamin proteins have been identified, key factors driving the nuclear lamina dynamics remain elusive. Here we identified CDK1-elicited phosphorylation sites on endogenous Lamin A/C and characterized their functions in regulation of the nuclear lamina. Specifically, mass spectrometry revealed CDK1-mediated phosphorylation of Lamin A/C at the N-terminal Thr19/Ser22 and the C-terminal Ser390/Ser392 during mitosis. Importantly, the phospho-mimicking 4D mutant T19D/S22D/S390D/S392D completely disrupted Lamin A filamentous structure in interphase cells. Conversely, the non-phosphorylatable mutant T19A/S22A and especially the 4A mutant T19A/S22A/S390A/S392A protected Lamin A from depolymerization during mitosis. These results suggest that phosphorylation and dephosphorylation of both N- and C-terminal sites regulate the nuclear lamina dynamics. Engineering the non-phosphorylatable mutant T19A/S22A into the endogenous LMNA gene resulted in nuclear abnormalities and micronucleus formation during telophase. Perturbation of the Lamin A phosphorylation is shown to prevent proper nuclear envelope dynamics and impair nuclear integrity. These findings reveal a previously undefined link between the CDK1-elicited Lamin A phosphorylation dynamics, nuclear envelope plasticity, and genomic stability during the cell cycle.

中文翻译：

---

核纤层蛋白 A/C 的磷酸化调节核膜的结构完整性


在有丝分裂进入和退出过程中核层的动态分解和重建分别是高等真核细胞增殖的关键步骤。尽管已经确定了核纤层蛋白的许多翻译后修饰，但驱动核层动力学的关键因素仍然难以捉摸。在这里，我们在内源性 Lamin A/C 上鉴定了 CDK1 诱导的磷酸化位点，并表征了它们在调节核层中的功能。具体而言，质谱分析揭示了有丝分裂期间 CDK1 介导的 Lamin A/C 在 N 端 Thr19/Ser22 和 C 端 Ser390/Ser392 的磷酸化。重要的是，磷酸化模拟 4D 突变体 T19D/S22D/S390D/S392D 完全破坏了间期细胞中的 Lamin A 丝状结构。相反，不可磷酸化突变体 T19A/S22A，尤其是 4A 突变体 T19A/S22A/S390A/S392A 保护 Lamin A 在有丝分裂期间免受解聚。这些结果表明，N 端和 C 端位点的磷酸化和去磷酸化调节核层动力学。将不可磷酸化突变体 T19A/S22A 工程化到内源性 LMNA 基因中导致末期核异常和微核形成。Lamin A 磷酸化的扰动被证明会阻止适当的核膜动力学并损害核完整性。这些发现揭示了 CDK1 诱导的 Lamin A 磷酸化动力学、核膜可塑性和细胞周期期间基因组稳定性之间以前未定义的联系。