DNA methylation, as an essential epigenetic modification found in mammals and plants, has been implicated to play an important role in insect reproduction. However, the functional role and the regulatory mechanism of DNA methylation during insect organ or tissue development are far from being clear. Here, we found that DNA methylation inhibitor (5-aza-dC) treatment in newly molted pupae decreased the chitin content of pupal wing discs and adult wings and resulted in wing deformity of Bombyx mori. Transcriptome analysis revealed that the up-regulation of chitinase 10 (BmCHT10) gene might be related to the decrease of chitin content induced by 5-aza-dC treatment. Further, the luciferase activity assays demonstrated that DNA methylation suppressed the promoter activity of BmCHT10 by down-regulating the transcription factor, homeobox protein araucan (Bmara). Electrophoretic mobility shift assay, DNA pull-down and chromatin immunoprecipitation demonstrated that Bmara directly bound to the BmCHT10 promoter. Therefore, DNA methylation is involved in keeping the structural integrity of the silkworm wings from unwanted chitin degradation, as a consequence, it promotes the wing development of B. mori. This study reveals that DNA methylation plays an important role in the wing development of B. mori. Our results support that the indirect transcriptional repression of a chitin degradation-related gene BmCHT10 by DNA methylation is necessary to keep the proper wing development in B. mori.

中文翻译：

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DNA甲基化可通过抑制家蚕Bombyx mori中Bmara介导的几丁质酶表达来抑制甲壳质降解并促进机翼发育。

DNA甲基化是在哺乳动物和植物中发现的一种重要的表观遗传修饰，被认为在昆虫繁殖中起着重要作用。但是，在昆虫器官或组织发育过程中DNA甲基化的功能作用和调控机制尚不清楚。在这里，我们发现在新蜕化的up中进行DNA甲基化抑制剂（5-aza-dC）处理可降低p翅片和成年翅的几丁质含量，并导致家蚕的翅畸形。转录组分析显示几丁质酶10（BmCHT10）基因的上调可能与5-氮杂-dC处理诱导的几丁质含量降低有关。此外，萤光素酶活性测定表明，DNA甲基化可通过下调转录因子来抑制BmCHT10的启动子活性，同源盒蛋白araucan（Bmara）。电泳迁移率变动分析，DNA下拉和染色质免疫沉淀表明Bmara直接与BmCHT10启动子结合。因此，DNA甲基化参与了蚕翅膀的结构完整性，以防止不需要的甲壳质降解，因此，它促进了桑蚕的翅膀发育。这项研究表明，DNA甲基化在桑蚕的翅膀发育中起着重要作用。我们的结果支持通过甲基化对甲壳质降解相关基因BmCHT10的间接转录抑制，对于保持桑蚕中适当的翅膀发育是必要的。DNA甲基化涉及保持蚕翅膀结构的完整性，以防止不希望的甲壳质降解，因此，它促进了桑蚕的翅膀发育。这项研究表明，DNA甲基化在桑蚕的翅膀发育中起着重要作用。我们的结果支持通过甲基化对甲壳质降解相关基因BmCHT10的间接转录抑制，对于保持桑蚕中适当的翅膀发育是必要的。DNA甲基化涉及保持蚕翅膀结构的完整性，以防止不希望的甲壳质降解，因此，它促进了桑蚕的翅膀发育。这项研究表明，DNA甲基化在桑蚕的翅膀发育中起着重要作用。我们的结果支持通过甲基化对甲壳质降解相关基因BmCHT10的间接转录抑制，对于保持桑蚕中适当的翅膀发育是必要的。