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A SUMO-ubiquitin relay recruits proteasomes to chromosome axes to regulate meiotic recombination

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Science  27 Jan 2017:
Vol. 355, Issue 6323, pp. 403-407
DOI: 10.1126/science.aaf6407

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Proteasomes and SUMO wrestle chromosomes

Meiosis is the double cell division that generates haploid gametes from diploid parental cells. Pairing of homologous chromosomes during the first meiotic division ensures that each gamete receives a complete set of chromosomes. The proteasome, on the other hand, is a molecular machine that degrades proteins tagged for destruction within the cell (see the Perspective by Zetka). Ahuja et al. show that the proteasome is also involved in ensuring that homologous chromosomes pair with each other during meiosis. Rao et al. show that the SUMO (small ubiquitin-like modifier) protein, ubiquitin, and the proteasome localize to the axes between homologous chromosomes. In this location, they help mediate chromosome pairing and recombination between homologs.

Science, this issue p. 349, p. 408; see also p. 403

Abstract

Meiosis produces haploid gametes through a succession of chromosomal events, including pairing, synapsis, and recombination. Mechanisms that orchestrate these events remain poorly understood. We found that the SUMO (small ubiquitin-like modifier)–modification and ubiquitin-proteasome systems regulate the major events of meiotic prophase in mouse. Interdependent localization of SUMO, ubiquitin, and proteasomes along chromosome axes was mediated largely by RNF212 and HEI10, two E3 ligases that are also essential for crossover recombination. RNF212-dependent SUMO conjugation effected a checkpointlike process that stalls recombination by rendering the turnover of a subset of recombination factors dependent on HEI10-mediated ubiquitylation. We propose that SUMO conjugation establishes a precondition for designating crossover sites via selective protein stabilization. Thus, meiotic chromosome axes are hubs for regulated proteolysis via SUMO-dependent control of the ubiquitin-proteasome system.

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