G2 histone methylation is required for the proper segregation of chromosomes
G2 histone methylation is required for the proper segregation of chromosomes
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DOI：
10.1242/jcs.045351
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发表时间：
2009-08-15
影响因子：
4
通讯作者：
Hendzel, Michael J.
中科院分区：
文献类型：
--
作者：
Heit, Ryan;Rattner, Jerome B.;Hendzel, Michael J.
已知组蛋白H3（H3 K9 me 3）上赖氨酸9的三甲基化对于正确的染色体分离和在G2晚期增加都是必要的。我们研究了晚期G2甲基化的作用，特别是在有丝分裂进程中，通过使用通用甲基化抑制剂腺苷二醛（AdOx）在有丝分裂前抑制甲基化2小时。AdOx抑制细胞内的所有甲基化事件，但通过将处理时间缩短至2小时并研究有丝分裂细胞，唯一受影响的甲基化事件是发生在G2晚期的甲基化事件。我们发现，在这段时间内的甲基化事件对于正确的有丝分裂至关重要。用AdOx处理观察到染色体的错误分离。通过对组蛋白修饰的研究，我们发现抑制晚期G2甲基化会影响H3 K9和H4 K20的三甲基化。有丝分裂检查点是活跃的，许多动粒蛋白正确定位，然而，这些细胞中的臂间染色质被发现不那么紧凑（致密）。臂间异染色质的完整性降低可能是AdOx处理细胞中着丝粒张力明显降低和纺锤体组装检查点激活的原因。我们推测晚期G2甲基化是正确的臂间异染色质形成所必需的。结果表明，异染色质完整性的降低可能会干扰微管与染色体的连接，并干扰正确的微管-动粒连接对张力的正确感知，这两种情况都将导致有丝分裂检查点的激活。
Trimethylation of lysine 9 on histone H3 (H3K9me3) is known both to be necessary for proper chromosome segregation and to increase in late G2. We investigated the role of late G2 methylation, specifically in mitotic progression, by inhibiting methylation for 2 hours prior to mitosis using the general methylation inhibitor adenosine dialdehyde (AdOx). AdOx inhibits all methylation events within the cell but, by shortening the treatment length to 2 hours and studying mitotic cells, the only methylation events that are affected are those that occur in late G2. We discovered that methylation events in this time period are crucial for proper mitosis. Mis-segregation of chromosomes is observed with AdOx treatment. Through studies of histone modifications, we have found that inhibiting late G2 methylation affects trimethylation of H3K9 and H4K20. The mitotic checkpoint is active and many kinetochore proteins localize properly, however, pericentric chromatin in these cells is found to be less compact (dense). The reduced integrity of pericentric heterochromatin might be responsible for a noted loss of tension at the centromere in AdOx-treated cells and activation of the spindle assembly checkpoint. We postulate that late G2 methylation is necessary for proper pericentric heterochromatin formation. The results suggest that a reduction in heterochromatin integrity might interfere both with microtubule attachment to chromosomes and with the proper sensing of tension from correct microtubule-kinetochore connections, either of which will result in activation of the mitotic checkpoint.