RBPL-1 Promotes Meiotic Homolog Pairing Through Its Conserved DWNN Domain in Caenorhabditis elegans

Accurate chromosome segregation during meiosis depends on precise homolog pairing. This process is driven by a series of specialized proteins that link chromosomes to cytoskeletal motors and coordinate chromosome movement for homolog recognition and alignment. Here, we identified RBPL-1, the Caenorhabditis elegans homolog of RBBP6, as a germline-expressed regulator essential for proper homolog pairing and associated nuclear reorganization. Depletion of RBPL-1 impaired the formation of clusters of the LINC complex and CHK-2 kinase within the nuclear periphery. Furthermore, we showed that RBPL-1 regulates the protein abundance of ZIM/HIM-8-family proteins and PLK-2 kinase, two critical mediators of homolog pairing. Notably, RBPL-1's role in homolog pairing is independent of the RING finger domain and Zn knuckle motif, which are proposed to mediate ubiquitination and alternative polyadenylation (APA)/mRNA processing respectively. Instead, we reveal that the evolutionarily conserved yet functionally enigmatic DWNN domain is essential for RBPL-1's function in homolog pairing. In summary, our findings demonstrate that RBPL-1 contributes to meiotic homolog pairing through its DWNN domain, by mediating nuclear reorganization and controlling the abundance of essential pairing factors.