Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
Queen Mary University of London, E1 4NS, UK.
Mol Biol Cell. 2023 Sep 1;34(10):ar99. doi: 10.1091/mbc.E23-03-0108. Epub 2023 Jul 12.
Centromere () identity is specified epigenetically by specialized nucleosomes containing evolutionarily conserved -specific histone H3 variant CENP-A (Cse4 in , CENP-A in humans), which is essential for faithful chromosome segregation. However, the epigenetic mechanisms that regulate Cse4 function have not been fully defined. In this study, we show that cell cycle-dependent methylation of Cse4-R37 regulates kinetochore function and high-fidelity chromosome segregation. We generated a custom antibody that specifically recognizes methylated Cse4-R37 and showed that methylation of Cse4 is cell cycle regulated with maximum levels of methylated Cse4-R37 and its enrichment at the chromatin occur in the mitotic cells. Methyl-mimic mutant exhibits synthetic lethality with kinetochore mutants, reduced levels of -associated kinetochore proteins and chromosome instability (CIN), suggesting that mimicking the methylation of Cse4-R37 throughout the cell cycle is detrimental to faithful chromosome segregation. Our results showed that SPOUT methyltransferase Upa1 contributes to methylation of Cse4-R37 and overexpression of leads to CIN phenotype. In summary, our studies have defined a role for cell cycle-regulated methylation of Cse4 in high-fidelity chromosome segregation and highlight an important role of epigenetic modifications such as methylation of kinetochore proteins in preventing CIN, an important hallmark of human cancers.
着丝粒()的身份是通过含有进化上保守的 -特异性组蛋白 H3 变体 CENP-A(在 中为 Cse4，在人类中为 CENP-A)的专门核小体来特异性地表观遗传指定的，这对于忠实的染色体分离是必不可少的。然而，调节 Cse4 功能的表观遗传机制尚未完全定义。在这项研究中，我们表明 Cse4-R37 的细胞周期依赖性甲基化调节着丝粒功能和高保真染色体分离。我们生成了一种定制的抗体，该抗体特异性识别甲基化的 Cse4-R37，并表明 Cse4 的甲基化是细胞周期调节的，具有最大水平的甲基化 Cse4-R37 及其在 染色质中的富集发生在有丝分裂细胞中。甲基模拟 突变体与着丝粒突变体表现出合成致死性， -相关的着丝粒蛋白水平降低和染色体不稳定 (CIN)，这表明在整个细胞周期中模拟 Cse4-R37 的甲基化对忠实的染色体分离是有害的。我们的研究结果表明，SPOUT 甲基转移酶 Upa1 有助于 Cse4-R37 的甲基化，而过表达 导致 CIN 表型。总之，我们的研究定义了 Cse4 细胞周期调节甲基化在高保真染色体分离中的作用，并强调了表观遗传修饰(如着丝粒蛋白的甲基化)在防止 CIN 中的重要作用，CIN 是人类癌症的一个重要标志。
