MJL-1 is a nuclear envelope protein required for homologous chromosome pairing and regulation of synapsis during meiosis in C. elegans

Interactions between chromosomes and LINC (linker of nucleoskeleton and cytoskeleton) complexes in the nuclear envelope (NE) promote homolog pairing and synapsis during meiosis. By tethering chromosomes to cytoskeletal motors, these connections lead to processive chromosome movements along the NE. This activity is usually mediated by telomeres, but in the nematode Caenorhabditis elegans, special chromosome regions called pairing centers (PCs) have acquired this meiotic function. Here, we identify a previously uncharacter-ized meiosis-specific NE protein, MJL-1 (MAJIN-Like-1), that is essential for interactions between PCs and LINC complexes in C. elegans. Mutations in MJL-1 eliminate active chromosome movements during meiosis, resulting in nonhomologous synapsis and impaired homolog pairing. Fission yeast and mice also require NE proteins to connect chromosomes to LINC complexes. Extensive similarities in the molecular architecture of meiotic chro-mosome-NE attachments across eukaryotes suggest a common origin and/or functions of this architecture during meiosis.

Automated summary

Interactions between chromosomes and LINC complexes in the nuclear envelope play a critical role in promoting homolog pairing and synapsis during meiosis. MJL-1, a meiosis-specific NE protein, is essential for these interactions in C. elegans. Disruption of MJL-1 results in impaired chromosome movements, nonhomologous synapsis, and defective homolog pairing during meiosis. The similarities in the molecular architecture of meiotic chromosome-NE attachments across different organisms suggest a common origin and/or function of this structure.