Department of Genetics, University of Georgia, Athens, GA, 30602, USA.
Department of Entomology, University of Georgia, Athens, GA, 30602, USA.
Epigenetics Chromatin. 2019 Jan 7;12(1):6. doi: 10.1186/s13072-018-0246-5.
The function of cytosine (DNA) methylation in insects remains inconclusive due to a lack of mutant and/or genetic studies.
Here, we provide evidence for the functional role of the maintenance DNA methyltransferase 1 (Dnmt1) in an insect using experimental manipulation. Through RNA interference (RNAi), we successfully posttranscriptionally knocked down Dnmt1 in ovarian tissue of the hemipteran Oncopeltus fasciatus (the large milkweed bug). Individuals depleted for Dnmt1, and subsequently DNA methylation, failed to reproduce. Eggs were inviable and declined in number, and nuclei structure of follicular epithelium was aberrant. Erasure of DNA methylation from gene or transposon element bodies did not reveal a direct causal link to steady-state mRNA levels in somatic cells. These results reveal an important function of Dnmt1 seemingly not contingent on directly controlling gene expression.
This study provides direct experimental evidence for a functional role of Dnmt1 in egg production and embryo viability and uncovers a trivial role, if any, for DNA methylation in control of gene expression in O. fasciatus.
由于缺乏突变体和/或遗传研究，昆虫中胞嘧啶（DNA）甲基化的功能仍不清楚。
在这里，我们通过实验操作提供了维持 DNA 甲基转移酶 1（Dnmt1）在昆虫中具有功能作用的证据。通过 RNA 干扰（RNAi），我们成功地在后转录水平上敲低了半翅目昆虫（大斑蝽）卵巢组织中的 Dnmt1。Dnmt1 耗尽的个体，随后是 DNA 甲基化，无法繁殖。卵子无法存活且数量减少，滤泡上皮细胞核结构异常。从基因或转座子元件体中去除 DNA 甲基化并没有显示出与体细胞中稳定 mRNA 水平之间的直接因果关系。这些结果揭示了 Dnmt1 的一个重要功能，似乎不依赖于直接控制基因表达。
本研究为 Dnmt1 在卵子产生和胚胎活力中的功能作用提供了直接的实验证据，并揭示了 DNA 甲基化在 O. fasciatus 中控制基因表达的微不足道的作用（如果有的话）。
