Microtubules methylation LC-MSMS

Microtubules are critical for mitosis, cell motility, and protein and organelle transport, and are a validated target for anticancer drugs. However, tubulin regulation and recruitment in these cellular processes is less understood. Post-translational modifications of tubulin are proposed to regulate microtubule functions and dynamics. Although many such modifications have been investigated, tubulin methylations and enzymes responsible for methylation have only recently begun to be described. Here we report that N-lysine methyl transferase KMT5A (SET8/PR‑Set7), which methylates histone H4K20, also methylates α‑tubulin. Furthermore, the transcription factor LSF binds both tubulin and SET8, and enhances α-tubulin methylation in vitro, countered by FQI1, a specific small molecule inhibitor of LSF. Thus, the three SET8, LSF, and tubulin, all essential for mitotic progression, interact with each other. Overall, these results point to dual functions for both SET8 and LSF not only in chromatin regulation, but also for cytoskeletal modification.微管（Microtubules）在有丝分裂、细胞运动以及蛋白质与细胞器运输过程中发挥关键作用，同时亦是抗癌药物的已验证靶点。然而，学界对微管蛋白在上述细胞过程中的调控与募集机制仍缺乏充分认知。有假说提出，微管蛋白的翻译后修饰可调控微管的功能与动态特性。尽管已有诸多此类修饰被深入研究，但微管蛋白的甲基化及其相关甲基化酶的研究，直至近年才逐步得到阐释。本研究发现，N-赖氨酸甲基转移酶KMT5A（SET8/PR-Set7）——该酶此前被报道可甲基化组蛋白H4K20——同时也能够甲基化α-微管蛋白。此外，转录因子LSF可同时结合微管蛋白与SET8，并在体外增强α-微管蛋白的甲基化水平，该调控作用可被LSF的特异性小分子抑制剂FQI1所拮抗。综上，SET8、LSF与微管蛋白三者均为有丝分裂进程所必需，且彼此间存在相互作用。总体而言，本研究结果表明，SET8与LSF不仅在染色质调控中具备双重功能，同时也参与细胞骨架的修饰过程。