In meiosis, telomeres attach to the inner nuclear membrane (INM) and drive the chromosome movement required for homolog pairing and recombination. Researchers address the question of how telomeres are structurally adapted for the meiotic task.
They 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, authors uncover a positive feedback between telomere attachment and chromosome movement, revealing a comprehensive regulatory network underlying meiosis-specific telomere function in mammals.