UC Berkeley

Faithful segregation of homologous chromosomes during meiosis requires pairing, synapsis, and crossing-over. In the nematode Caenorhabditis elegans, homolog pairing and synapsis depend on pairing centers, special regions near one end of each chromosome that interact with the nuclear envelope and cytoplasmic microtubules. Pairing centers are required for nuclear reorganization at the onset of meiosis. Here, I show that pairing centers recruit the Polo-like kinase PLK-2 to induce nuclear envelope remodeling, chromosome pairing, and synapsis. Recruitment of PLK-2 is also required to mediate a cell cycle delay and selective apoptosis of nuclei containing unsynapsed chromosomes, establishing a molecular link between these two quality control mechanisms. I also show that the checkpoint kinase CHK-2 is recruited to the interface of pairing centers and nuclear envelope proteins, consistent with its role in promoting homolog interactions and nuclear reorganization. Interestingly, PLK-2 is later recruited to the axes of paired and synapsed chromosomes where it plays a downstream role in synaptonemal complex dynamics. This work reveals new functions for the conserved family of Polo-like kinases, and advances our understanding of how meiotic processes are properly coordinated to ensure transmission of genetic information from parents to progeny.