Dynamic and stable regulation of aggression through DNA methylation

 描述(申请人提供)：攻击性行为在我们的社会中是一种破坏性的影响，因为根据定义，它的目的是造成身体或心理上的伤害。在人类中，在不利的社会环境中长大会强烈地影响攻击性倾向的发展，而基因变异也会使个人容易受到攻击性。DNA甲基化是一种表观遗传修饰，存在于相对稳定的模式中，但可以在特定的位置随环境的变化而改变。这种稳定/动态的二元性潜在地将DNA甲基化置于基因型别和环境对行为的影响之间的调节界面。这项提议将调查DNA甲基化是否介导了基因和环境对蜜蜂攻击性的影响，蜜蜂是一个表现出良好特征的攻击行为的模型，并且与果蝇不同，它具有一个功能齐全的、类似哺乳动物的甲基化系统。不同品系的蜜蜂具有不同的攻击性，我们之前的工作表明，高攻击性的非洲蜜蜂(AHB)在脑基因表达和DNA甲基化方面与攻击性较弱的欧洲蜜蜂(EHB)不同。此外，通过暴露在报警信息素中而引发攻击的EHB显示出一些相同基因的表达变化。我们将测试这一假设，即DNA甲基化作为一个稳定的表观遗传标记来调节攻击性的遗传差异，同时也作为一个动态调节器来响应促进攻击性的环境刺激。在哺乳动物中，DNA甲基化模式可以通过十-十一转位酶(Tet)和胸腺嘧啶DNA糖基酶(TDG)介导的活性DNA去甲基化来调节。为了确定蜜蜂中是否存在依赖Tet/TDG的DNA去甲基化机制并调节攻击性，将使用RNA干扰(RNAi)在蜜蜂的大脑中击倒TDG；初步结果显示，敲除约20%。我们将测量TDG击倒蜜蜂的DNA去甲基化和侵略性，以及氧化的5-甲基胞嘧啶衍生物的积累，这些衍生物是其他生物中活跃的DNA甲基化的已知中间体。为了探索DNA甲基化是否也将攻击性确立为与基因型相关的稳定性状，我们将检查AHB和EHB中攻击性相关基因的DNA甲基化模式的稳定性。最后，我们将比较遗传和环境诱导的攻击环境中攻击相关基因的甲基化模式。我们希望在两者之间观察到类似的甲基化模式，支持我们的假设，即DNA甲基化是一种潜在的基因和环境对攻击性影响的调节因素。

 DESCRIPTION (provided by applicant): Aggressive behavior is a damaging influence in our society, since by definition it is intended to inflict physical or psychological harm. In humans, growing up in a socially adverse environment can strongly influence the development of aggressive tendencies, and genotypic variation can also predispose individuals to aggression. DNA methylation is an epigenetic modification that exists in relatively stable patterns, but can change at specific loci in response to the environment. This stable/dynamic duality potentially places DNA methylation at the regulatory interface between genotypic and environmental influences on behavior. This proposal will investigate whether DNA methylation mediates the influences of genotype and environment on aggression in the honey bee, a model that exhibits well-characterized aggressive behaviors, and unlike the fruit fly, has a fully functional, mammalian-like methylation system. Strains of bees differ in their aggressiveness, and our prior work has shown that the highly aggressive African honey bee (AHB) shows differences in brain gene expression and DNA methylation from the less aggressive European honey bee (EHB). In addition, EHB provoked to aggression by exposure to alarm pheromone show expression changes in some of the same genes. We will test the hypothesis that DNA methylation serves as a stable epigenetic mark regulating inherited differences in aggression, while also acting as a dynamic regulator responding to environmental stimuli that promote aggression. In mammals, DNA methylation patterns can be modulated through active DNA demethylation, which is mediated by ten-eleven translocase (TET) and thymine DNA glycosylase (TDG) enzymes. To determine whether a TET/TDG-dependent DNA demethylation mechanism exists in bees and regulates aggression, TDG will be knocked down in the bee brain using RNA interference (RNAi); preliminary results indicate a ca. 20% knockdown. We will measure DNA demethylation and aggression in the TDG knockdown bees, as well as the accumulation of oxidized 5-methylcytosine derivatives, which are known intermediates of active DNA methylation in other organisms. To explore whether DNA methylation also establishes aggression as a stable trait associated with genotype, we will examine the stability of DNA methylation patterns at aggression-related genes in AHB and EHB. Lastly, we will compare methylation patterns at aggression-related genes between the hereditary and environmentally-induced aggressive contexts. We expect to observe similar methylation patterns between the two, supporting our hypothesis that DNA methylation is a regulator underlying both genotypic and environmental effects on aggression.