Alignment of Homologous Chromosomes and Effective Repair of Programmed DNA Double-Strand Breaks during Mouse Meiosis Require the Minichromosome Maintenance Domain Containing 2 (MCMDC2) Protein.
Alignment of Homologous Chromosomes and Effective Repair of Programmed DNA Double-Strand Breaks during Mouse Meiosis Require the Minichromosome Maintenance Domain Containing 2 (MCMDC2) Protein.
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DOI：
10.1371/journal.pgen.1006393
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发表时间：
2016-10
期刊：
影响因子：
4.5
通讯作者：
Tóth A
中科院分区：
文献类型：
--
作者：
Finsterbusch F;Ravindranathan R;Dereli I;Stanzione M;Tränkner D;Tóth A
第一次减数分裂期间的有序染色体分离需要减数分裂重组以在同源染色体（同源体）之间形成交叉。微型染色体维持（MCM）解旋酶家族的成员与减数分裂重组有关。此外，它们还在 DNA 复制起始、DNA 错配修复和有丝分裂 DNA 双链断裂修复中发挥作用。在这里，我们讨论了 MCMDC2 的功能，MCMDC2 是一种非典型但保守的 MCM 蛋白，其在脊椎动物中的功能尚未有报道。虽然我们没有发现 MCMDC2 在有丝分裂细胞中发挥重要作用，但我们的工作表明，由于减数分裂重组中的关键功能，MCMDC2 对于两性的生育能力都是至关重要的。减数分裂重组始于将 DNA 双链断裂引入基因组。断裂位点的 DNA 末端被切除。由此产生的 3-prime 单链 DNA 突出端会招募 RAD51 和 DMC1 重组酶，从而促进被切除的 DNA 末端入侵同源双链 DNA。每条染色体上的多链入侵促进同源染色体的排列，这是减数分裂过程中同源染色体间交叉形成的先决条件。我们发现，虽然断裂位点的DNA末端明显被切除，并且它们招募了RAD51和DMC1重组酶，但在没有MCMDC2的情况下，这些重组酶无法有效促进同源染色体的对齐。因此，被认为标记早期重组中间体的 RAD51 和 DMC1 焦点在 Mcmdc2-/- 性母细胞中异常持久。重要的是，链入侵稳定 MSH4 蛋白（标志着更高级的重组中间体）并没有在 Mcmdc2-/- 性母细胞中有效形成焦点。因此，我们的工作表明，MCMDC2 在 DNA 链入侵事件的形成或稳定中起着重要作用，这些事件促进同源物比对并为减数分裂重组过程中同源物间交叉的形成提供基础。在二倍体生物中，每条染色体都以两个不同但同源的副本存在。为了产生适合受精的单倍体配子，这些同源染色体必须在减数分裂期间分离。为了确保正确的染色体分离，在包括哺乳动物在内的大多数类群的减数分裂早期，同源染色体必须通过同源间交叉排列并连接。这些过程的缺陷会导致不育和配子非整倍性。同源染色体的排列和交叉形成需要产生DNA双链断裂并通过减数分裂重组修复DNA断裂。作为修复过程的一部分，DNA 断裂产生的单链 DNA 末端侵入同源 DNA 序列并将其用作修复模板。 DNA 链入侵事件导致同源染色体对齐，并作为交叉的前体。我们发现减数分裂重组关键取决于解旋酶相关的含有 2 蛋白（MCMDC2）的微型染色体维持结构域。 MCMDC2 可能促进连接同源染色体的 DNA 链入侵事件的形成和/或稳定。因此，MCMDC2是DNA断裂所必需的，以有效促进同源染色体的对齐。这项工作揭示了 MCMDC2 在哺乳动物重组中的关键作用，并为理解减数分裂过程中重组如何在同源染色体之间建立连接迈出了重要的一步。
Orderly chromosome segregation during the first meiotic division requires meiotic recombination to form crossovers between homologous chromosomes (homologues). Members of the minichromosome maintenance (MCM) helicase family have been implicated in meiotic recombination. In addition, they have roles in initiation of DNA replication, DNA mismatch repair and mitotic DNA double-strand break repair. Here, we addressed the function of MCMDC2, an atypical yet conserved MCM protein, whose function in vertebrates has not been reported. While we did not find an important role for MCMDC2 in mitotically dividing cells, our work revealed that MCMDC2 is essential for fertility in both sexes due to a crucial function in meiotic recombination. Meiotic recombination begins with the introduction of DNA double-strand breaks into the genome. DNA ends at break sites are resected. The resultant 3-prime single-stranded DNA overhangs recruit RAD51 and DMC1 recombinases that promote the invasion of homologous duplex DNAs by the resected DNA ends. Multiple strand invasions on each chromosome promote the alignment of homologous chromosomes, which is a prerequisite for inter-homologue crossover formation during meiosis. We found that although DNA ends at break sites were evidently resected, and they recruited RAD51 and DMC1 recombinases, these recombinases were ineffective in promoting alignment of homologous chromosomes in the absence of MCMDC2. Consequently, RAD51 and DMC1 foci, which are thought to mark early recombination intermediates, were abnormally persistent in Mcmdc2-/- meiocytes. Importantly, the strand invasion stabilizing MSH4 protein, which marks more advanced recombination intermediates, did not efficiently form foci in Mcmdc2-/- meiocytes. Thus, our work suggests that MCMDC2 plays an important role in either the formation, or the stabilization, of DNA strand invasion events that promote homologue alignment and provide the basis for inter-homologue crossover formation during meiotic recombination. Each chromosome is present in two distinct but homologous copies in diploid organisms. To generate haploid gametes suitable for fertilization, these homologous chromosomes must segregate during meiosis. To ensure correct chromosome segregation, homologous chromosomes must align and become connected by inter-homologue crossovers during early meiosis in most taxa including mammals. Defects in these processes result in infertility and aneuploidies in gametes. Alignment of homologous chromosomes and crossover formation entail generation of DNA double-strand breaks and repair of DNA breaks by meiotic recombination. As part of the repair process, single-stranded DNA ends resulting from DNA breaks invade homologous DNA sequences and use them as repair templates. DNA strand invasion events lead to the alignment of homologous chromosomes, and serve as precursors for crossovers. We discovered that meiotic recombination critically depends on the helicase-related minichromosome maintenance domain containing 2 protein (MCMDC2). MCMDC2 likely promotes the formation and/or stabilization of DNA strand invasion events that connect homologous chromosomes. Thus, MCMDC2 is required for DNA breaks to effectively promote alignment of homologous chromosomes. This work reveals a crucial role for MCMDC2 in recombination in mammals, and constitutes an important step in understanding how recombination establishes connections between homologous chromosomes during meiosis.
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DOI：
10.1126/science.1219379
发表时间：
2012-09-07
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Cloud V;Chan YL;Grubb J;Budke B;Bishop DK
通讯作者：
Bishop DK
果蝇 MCM8 REC 驱动减数分裂交叉的形成
影响因子：
4.5
作者：
Blanton, HL;Radford, SJ;Sekelsky, J
通讯作者：
Sekelsky, J
影响因子：
64.5
作者：
Blat, Y;Protacio, RU;Kleckner, N
通讯作者：
Kleckner, N
DOI：
10.1073/pnas.1113524108
发表时间：
2011-10-25
影响因子：
11.1
作者：
Hartford, Suzanne A.;Luo, Yunhai;Schimenti, John C.
通讯作者：
Schimenti, John C.
影响因子：
64.8
作者：
Bergerat, A;deMassy, B;Forterre, P
通讯作者：
Forterre, P