Sycp2 is essential for synaptonemal complex assembly, early meiotic recombination and homologous pairing in zebrafish spermatocytes
Sycp2 is essential for synaptonemal complex assembly, early meiotic recombination and homologous pairing in zebrafish spermatocytes
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DOI：
10.1371/journal.pgen.1008640
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发表时间：
2020-02
期刊：
影响因子：
4.5
通讯作者：
K. Takemoto;Yukiko Imai;Kenji Saito;Toshihiro Kawasaki;P. Carlton;K. Ishiguro;Noriyoshi Sakai
中科院分区：
文献类型：
--
作者：
K. Takemoto;Yukiko Imai;Kenji Saito;Toshihiro Kawasaki;P. Carlton;K. Ishiguro;Noriyoshi Sakai
减数分裂重组对于配子发生过程中同源染色体的忠实分离至关重要。重组的进展与减数分裂染色质结构的动态变化相关。然而，在脊椎动物中，减数分裂染色质的关键结构成分 Sycp2 是否是减数分裂重组启动所必需的尚不清楚。在这里，我们描述了 Sycp2 是斑马鱼精母细胞联会复合体组装和早期减数分裂事件所必需的。我们通过 N-乙基-N-亚硝基脲诱变进行的遗传筛选显示，ietsugu (its) 是一种 sycp2 基因中具有异常剪接位点的突变斑马鱼品系，在减数分裂前期 I 中表现出缺陷。与 TALEN 诱变产生的 sycp2 敲除突变相比，其突变似乎是一种亚等位性突变。利用这些 sycp2 亚型和敲除突变系，我们证明 Sycp2 是在野生型斑马鱼精母细胞端粒附近启动的联会复合体组装所必需的。因此，sycp2 敲除精母细胞中的同源配对、减数分裂重组酶 Dmc1/Rad51 和 RPA 的焦点以及 γH2AX 信号大大减少。综上所述，我们的数据表明 Sycp2 不仅在脊椎动物联会复合体的组装中发挥着关键作用，而且在早期减数分裂重组和同源配对中也发挥着关键作用。
Meiotic recombination is essential for faithful segregation of homologous chromosomes during gametogenesis. The progression of recombination is associated with dynamic changes in meiotic chromatin structures. However, whether Sycp2, a key structural component of meiotic chromatin, is required for the initiation of meiotic recombination is still unclear in vertebrates. Here, we describe that Sycp2 is required for assembly of the synaptonemal complex and early meiotic events in zebrafish spermatocytes. Our genetic screening by N-ethyl-N-nitrosourea mutagenesis revealed that ietsugu (its), a mutant zebrafish line with an aberrant splice site in the sycp2 gene, showed a defect during meiotic prophase I. The its mutation appeared to be a hypomorphic mutation compared to sycp2 knockout mutations generated by TALEN mutagenesis. Taking advantage of these sycp2 hypomorphic and knockout mutant lines, we demonstrated that Sycp2 is required for the assembly of the synaptonemal complex that is initiated in the vicinity of telomeres in wild-type zebrafish spermatocytes. Accordingly, homologous pairing, the foci of the meiotic recombinases Dmc1/Rad51 and RPA, and γH2AX signals were largely diminished in sycp2 knockout spermatocytes. Taken together, our data indicate that Sycp2 plays a critical role in not only the assembly of the synaptonemal complex, but also early meiotic recombination and homologous pairing, in vertebrates.