Roles of histone H3K9 methyltransferases during Drosophila spermatogenesis
Roles of histone H3K9 methyltransferases during Drosophila spermatogenesis
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DOI：
10.1007/s10577-012-9276-1
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发表时间：
2012-04
影响因子：
2.6
通讯作者：
Yuta Ushijima;Y. Inoue;Takahiro Konishi;Daishi Kitazawa;H. Yoshida;Kouhei Shimaji;H. Kimura;M. Yamaguchi
中科院分区：
文献类型：
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作者：
Yuta Ushijima;Y. Inoue;Takahiro Konishi;Daishi Kitazawa;H. Yoshida;Kouhei Shimaji;H. Kimura;M. Yamaguchi
通过组蛋白共价修饰对基因表达进行表观遗传调控对于生殖细胞发育非常重要。在哺乳动物中，组蛋白 H3 赖氨酸 9 (H3K9) 特异性组蛋白甲基转移酶 (HMTase)，例如 G9a、SETDB1 和 SUV39H，发挥着关键作用，但 H3K9 特异性 HMTase 在果蝇中的贡献仍有待阐明，尤其是在雄性精子中。在这里，我们使用 dG9a（果蝇 G9a 直向同源物）的特异性抗体进行了免疫细胞化学分析，并证明了从精子发生的生长到伸长阶段在细胞质中的定位。在随后的独木舟早期阶段，仅在细胞核中检测到强 dG9a 信号，表明其具有调节作用。然而，在整个这些阶段，纯合 dG9a 无效突变体中的单甲基化、二甲基化和三甲基化 H3K9 信号并未大幅降低。相比之下，杂合子 DmSetdb1 突变体在精子发生过程中单甲基化和三甲基化 H3K9 信号大幅减少，并且在纯合子 Su(var)3-9 突变体中也观察到单甲基化 H3K9 信号的类似减少。因此，DmSETDB1 可能主要负责 H3K9 的单甲基化和三甲基化，而 SU(VAR)3-9 则主要负责精子发生过程中 H3K9 的单甲基化。然而，减数分裂前精母细胞中 H3K9 甲基化的减少并不影响雄性减数分裂中的 X-Y 染色体分离，这表明它对于果蝇的精子发生可能并不重要。
Epigenetic regulation of gene expression by covalent modification of histones is important for germ line cell development. In mammals, histone H3 lysine 9 (H3K9)-specific histone methyltransferases (HMTases), such as G9a, SETDB1, and SUV39H, play critical roles, but the contribution of H3K9-specific HMTases inDrosophilaremains to be clarified, especially in male sperm. Here, we performed immunocytochemical analyses with a specific antibody to dG9a,DrosophilaG9a ortholog, and demonstrated localization in the cytoplasm from the growth to elongation stages of spermatogenesis. In the subsequent early canoe stage, strong dG9a signals were detected exclusively in nuclei, suggesting a regulatory role. However, mono-, di-, and trimethylated H3K9 signals were not extensively decreased in a homozygous dG9a null mutant throughout these stages. In contrast, mono- and trimethylated H3K9 signals were extensively decreased in a heterozygousDmSetdb1mutant during spermatogenesis, and similar reduction in monomethylated H3K9 signals was observed in a homozygousSu(var)3–9mutant. Therefore, DmSETDB1 is likely to be mainly responsible for mono- and trimethylation of H3K9 and SU(VAR)3–9 for monomethylation of H3K9 during spermatogenesis. However, the reduced methylation of H3K9 in premeiotic spermatocytes did not influence X–Y chromosome disjunction in male meiosis, suggesting that it may not be critical for spermatogenesis inDrosophila.