1
|
Abstract
The functions of the Bloom syndrome helicase (BLM) and its orthologs are well characterized in mitotic DNA damage repair, but their roles within the context of meiotic recombination are less clear. In meiotic recombination, multiple repair pathways are used to repair meiotic DSBs, and current studies suggest that BLM may regulate the use of these pathways. Based on literature from Saccharomyces cerevisiae, Arabidopsis thaliana, Mus musculus, Drosophila melanogaster, and Caenorhabditis elegans, we present a unified model for a critical meiotic role of BLM and its orthologs. In this model, BLM and its orthologs utilize helicase activity to regulate the use of various pathways in meiotic recombination by continuously disassembling recombination intermediates. This unwinding activity provides the meiotic program with a steady pool of early recombination substrates, increasing the probability for a DSB to be processed by the appropriate pathway. As a result of BLM activity, crossovers are properly placed throughout the genome, promoting proper chromosomal disjunction at the end of meiosis. This unified model can be used to further refine the complex role of BLM and its orthologs in meiotic recombination.
Collapse
Affiliation(s)
- Talia Hatkevich
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jeff Sekelsky
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Integrative Program in Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| |
Collapse
|
2
|
Hatkevich T, Kohl KP, McMahan S, Hartmann MA, Williams AM, Sekelsky J. Bloom Syndrome Helicase Promotes Meiotic Crossover Patterning and Homolog Disjunction. Curr Biol 2016; 27:96-102. [PMID: 27989672 DOI: 10.1016/j.cub.2016.10.055] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 10/25/2016] [Accepted: 10/27/2016] [Indexed: 11/28/2022]
Abstract
In most sexually reproducing organisms, crossover formation between homologous chromosomes is necessary for proper chromosome disjunction during meiosis I. During meiotic recombination, a subset of programmed DNA double-strand breaks (DSBs) are repaired as crossovers, with the remainder becoming noncrossovers [1]. Whether a repair intermediate is designated to become a crossover is a highly regulated decision that integrates several crossover patterning processes, both along chromosome arms (interference and the centromere effect) and between chromosomes (crossover assurance) [2]. Because the mechanisms that generate crossover patterning have remained elusive for over a century, it has been difficult to assess the relationship between crossover patterning and meiotic chromosome behavior. We show here that meiotic crossover patterning is lost in Drosophila melanogaster mutants that lack the Bloom syndrome helicase. In the absence of interference and the centromere effect, crossovers are distributed more uniformly along chromosomes. Crossovers even occur on the small chromosome 4, which normally never has meiotic crossovers [3]. Regulated distribution of crossovers between chromosome pairs is also lost, resulting in an elevated frequency of homologs that do not receive a crossover, which in turn leads to elevated nondisjunction.
Collapse
Affiliation(s)
- Talia Hatkevich
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA
| | - Kathryn P Kohl
- Department of Biology, Winthrop University, 701 Oakland Avenue, Rock Hill, SC 29733, USA
| | - Susan McMahan
- Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599-3280, USA; Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599-7100, USA
| | - Michaelyn A Hartmann
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA
| | - Andrew M Williams
- Department of Biology, Winthrop University, 701 Oakland Avenue, Rock Hill, SC 29733, USA
| | - Jeff Sekelsky
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA; Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599-3280, USA; Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599-7100, USA.
| |
Collapse
|