Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan.
Department of Cell and Molecular Biology, Karolinska Institute, Stockholm 171 77, Sweden.
Cell. 2015 Nov 19;163(5):1252-1266. doi: 10.1016/j.cell.2015.10.030. Epub 2015 Nov 5.
In meiosis, telomeres attach to the inner nuclear membrane (INM) and drive the chromosome movement required for homolog pairing and recombination. Here, we address the question of how telomeres are structurally adapted for the meiotic task. We identify a multi-subunit meiotic telomere-complex, TERB1/2-MAJIN, which takes over telomeric DNA from the shelterin complex in mouse germ cells. TERB1/2-MAJIN initially assembles on the INM sequestered by its putative transmembrane subunit MAJIN. In early meiosis, telomere attachment is achieved by the formation of a chimeric complex of TERB1/2-MAJIN and shelterin. The chimeric complex matures during prophase into DNA-bound TERB1/2-MAJIN by releasing shelterin, forming a direct link between telomeric DNA and the INM. These hierarchical processes, termed "telomere cap exchange," are regulated by CDK-dependent phosphorylation and the DNA-binding activity of MAJIN. Further, we uncover a positive feedback between telomere attachment and chromosome movement, revealing a comprehensive regulatory network underlying meiosis-specific telomere function in mammals.
在减数分裂中,端粒附着在内核膜(INM)上,并驱动同源配对和重组所需的染色体运动。在这里,我们探讨了端粒如何在结构上适应减数分裂任务的问题。我们鉴定了一个多亚基减数分裂端粒复合物,TERB1/2-MAJIN,它从小鼠生殖细胞中的庇护素复合物中接管端粒 DNA。TERB1/2-MAJIN 最初在其假定的跨膜亚基 MAJIN 隔离的 INM 上组装。在早期减数分裂中,通过形成 TERB1/2-MAJIN 和庇护素的嵌合复合物来实现端粒附着。嵌合复合物在前期通过释放庇护素成熟为 DNA 结合的 TERB1/2-MAJIN,在端粒 DNA 和 INM 之间形成直接联系。这些分层过程被称为“端粒帽交换”,受 CDK 依赖性磷酸化和 MAJIN 的 DNA 结合活性调节。此外,我们揭示了端粒附着和染色体运动之间的正反馈,揭示了哺乳动物中减数分裂特异性端粒功能的综合调控网络。
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