Helping Homologues to Find Their Partners DOI: 10.1038/Nrg2154 During Meiotic Prophase, Chromo- Are Sterile

RESEARCH HIGHLIGHTS

CHROMOSOME BIOLOGY Helping homologues to find their partners DOI: 10.1038/nrg2154 During meiotic prophase, chromo- are sterile. SUN1 distribution in proteins of the pairing centre local- somes attach to the nuclear envelope wild-type mice varies during the ize. The authors propose a model URLs through their telomeres, facilitating different stages of spermatogenesis, whereby chromosomes run through Entrez homologue pairing. Although the resembling the nuclear envelope a homology check that takes place UNC84A http://www.ncbi.nlm.nih. first description of this chromosome localization of telomeres in primary at SUN-1–ZYG-12 aggregates: gov/sites/entrez?Db=gene&C organization dates back more than a spermatocytes, and fluorescence if they find their partners, synapsis md=ShowDetailView&TermTo Search=77053 century, the molecular mechanisms in situ hybridization (FISH) analy- occurs; otherwise, they keep are still largely unknown. Two sis confirmed that telomeres searching for their homologues. groups now report that, in mice colocalize with SUN1 during mei- In mtf-1/sun-1(jf18) mutants, the and Caenorhabditis elegans, nuclear otic prophase. Telomere attachment homology check is impaired and non- inner membrane proteins have an to the nuclear envelope is impaired homologous synapsis takes place. important role in this process. in Sun1–/– mice, resulting in Altogether, these studies provide Min Han and colleagues showed defective pairing, synapsis and an important addition to our that mice knockout for the nuclear recombination between homologous understanding of the processes of envelope protein SUN1 (also chromosomes. chromosome dynamics during known as UNC84A) develop nor- In a second study, using forward meiosis, which might ultimately mally, but both males and females genetic screening in C. elegans, provide clues about the origins of Verena Jantsch and colleagues meiotic defects that impair human identified a missense mutation in fertility. the matefin gene, mtf-1/sun-1(jf18), Francesca Pentimalli that causes defects in meiotic ORIGINAL RESEARCH PAPERS Ding, X. & chromosome segregation. Using Xu, R. et al. SUN1 is required for telomere FISH, the authors showed that in attachment to nuclear envelope and mutant gonads chromosomes are gametogenesis in mice. Dev. Cell 12, 863–872 (2007) | Penkner, A. et al. The nuclear envelope unable to find their homologous protein Matefin/SUN-1 is required for partners, and instead engage in non- homologous pairing in C. elegans meiosis. homologous synapsis. Furthermore, Dev. Cell 12, 873–885 (2007) FURTHER READING Gerton, J. L. & Hawley, R. S. these mutants fail to form nuclear Homologous chromosome interactions in envelope aggregates of the ZYG-12 meiosis: diversity amidst conservation. Nature protein, which normally form where Rev. Genet. 6, 477–487 (2005)