Dynamic SUMO remodeling drives a series of critical events during the meiotic divisions in Caenorhabditis elegans

Abstract

Chromosome congression and segregation in C. elegans oocytes depend on a complex of conserved proteins that forms a ring around the center of each bivalent during prometaphase; these complexes are then removed from chromosomes at anaphase onset and disassemble as anaphase proceeds. Here, we uncover mechanisms underlying the dynamic regulation of these ring complexes (RCs), revealing a strategy by which protein complexes can be progressively remodeled during cellular processes. We find that the assembly, maintenance, and stability of RCs is regulated by a balance between SUMO conjugating and deconjugating activity. During prometaphase, the SUMO protease ULP-1 is targeted to the RCs but is counteracted by SUMO E2/E3 enzymes; then in early anaphase the E2/E3 enzymes are removed, enabling ULP-1 to trigger RC disassembly and completion of the meiotic divisions. Moreover, we found that SUMO regulation is essential to properly connect the RCs to the chromosomes and then also to fully release them in anaphase. Altogether, our work demonstrates that dynamic remodeling of SUMO modifications facilitates key meiotic events and highlights how competition between conjugation and deconjugation activity can modulate SUMO homeostasis, protein complex stability, and ultimately, progressive processes such as cell division.

Sumoylation regulates central spindle protein dynamics during chromosome segregation in oocytes

“…However, depletion of ULP-1 does not have a discernible effect on meiotic chromosome segregation ( Figure 5F). It should be noted that a recent report found ULP-1 in the midbivalent and also attributed a more important role for ULP-1 during meiosis I (Davis-Roca et al, 2018). These results show that ULP-1 is an essential protein but the lethality is unlikely to arise due to meiotic defects.…”

“…The SUMO protease ULP-1. A recent paper has found that ULP-1 depletion does have a more dramatic impact on chromosome segregation (Davis-Roca et al, 2018). A possible explanation for this discrepancy is the long RNAi incubations used in the mentioned study.…”

“…Acute depletion of BUB-1 and CLS-2 during oocyte meiosis. The role of BUB-1 and CLS-2, as well as other proteins, has been mainly addressed using protein depletion by means of RNAi, either on its own or in depletion/rescue experiments (Davis-Roca et al, 2018;Dumont et al, 2010;Laband et al, 2017;Muscat et al, 2015;Wignall and Villeneuve, 2009). These experiments use RNAi mostly for between 12 and 48 hours, but in some cases RNAi incubation have reached up to 72 hours.…”

“…Additionally, BUB-1 and CPC components are also present within the central spindle. The limited evidence on the dynamics of these proteins during meiosis I suggests that they do not necessarily occupy the same domains throughout anaphase (Dumont et al, 2010;Davis-Roca et al, 2017;Mullen and Wignall, 2017;Davis-Roca et al, 2018). Considering that i) the CPC and CLS-2 are essential for chromosome segregation and ii) BUB-1 also plays a role during chromosome segregation, we sought to focus our attention on these proteins and characterise their dynamics during anaphase I.…”

Excess crossovers impede faithful meiotic chromosome segregation inC. elegans

“…Slides were washed a final time and mounted in 0.5% p-phenylenediamine in 90% glycerol, 20mM Tris, pH 8.8, sealed with nail polish, and stored at 4°C prior to imaging.The following antibodies were used: rat anti-AIR-2 (1:500,Davis-Roca et al 2017), rabbit anti-SEP-1 (1:200, gift from Andy Golden), rabbit anti-BIR-1 (1:800, this study), mouse anti-SUMO (1:500, gift from Federico Pelisch), rabbit anti-BUB-1 (1:1000, Davis-Roca et al26 2018), rabbit anti-ASPM-1 (1:5000, gift from Arshad Desai), Mouse anti-a-tubulin-FITC (1:500, DM1a, Sigma) and rabbit anti-KLP-19 (1:2500, this study). KLP-19 and BIR-1 polyclonal antibodies were generated by Covance using recombinant GST-BIR-1 (Full length protein) andGST-KLP-19 (amino acids 371-1084) as antigens (purification performed as inDavis-Roca et al 2018). Antibody sera was then affinity purified and used at indicated concentrations.…”