Regional epigenetic differentiation of the Z Chromosome between sexes in a female heterogametic system
Regional epigenetic differentiation of the Z Chromosome between sexes in a female heterogametic system
复制标题
DOI：
10.1101/gr.248641.119
复制
发表时间：
2019-10-01
期刊：
影响因子：
7
通讯作者：
Yi, Soojin, V
中科院分区：
文献类型：
--
作者：
Sun, Dan;Maney, Donna L.;Yi, Soojin, V
在雄性异配子系统中，X染色体在雄性和雌性之间进行表观遗传分化，以促进剂量补偿。例如，雌性哺乳动物的X染色体大部分是失活的。相对于研究充分的雄性异配子系统，在雌性异配子物种中，雄性和雌性Z染色体之间的表观遗传分化程度往往缺乏完整的剂量补偿，目前还知之甚少。在这里，我们研究了两个远亲鸟类物种，即鸡和白喉麻雀的雄性和雌性Z染色体的染色体DNA甲基化景观。我们发现，在哺乳动物的模式，男性和女性的Z染色体在这些物种中表现出高度相似的模式的DNA甲基化，这是一致的弱或缺乏剂量补偿。我们进一步证明了雄性和雌性鸡Z染色体之间的表观遗传差异定位于几个区域，包括先前确定的雄性高甲基化区域1（MHM 1; CGNC：80601）。我们在鸡Z染色体上发现了一个雄性与雌性甲基化比率升高的新区域（雄性高甲基化区域2 [MHM 2]; CGNC：80602）。MHMI和MHM 2，尽管它们之间几乎没有序列相似性，但具有可能与它们的功能相关的相似分子特征。我们提出的证据与女性低甲基化的MHM和附近的基因上调一致。因此，尽管性别之间的甲基化差异很小，但雄性和雌性鸡Z染色体之间的极度局部化的DNA甲基化差异已经进化并影响附近区域的表达。我们的研究结果提供了新的见解，在女性异配子系统性别之间的基因表达的表观遗传调控。
In male heterogametic systems, the X Chromosome is epigenetically differentiated between males and females, to facilitate dosage compensation. For example, the X Chromosome in female mammals is largely inactivated. Relative to well-studied male heterogametic systems, the extent of epigenetic differentiation between male and female Z Chromosomes in female heterogametic species, which often lack complete dosage compensation, is poorly understood. Here, we examined the chromosomal DNA methylation landscapes of male and female Z Chromosomes in two distantly related avian species, namely chicken and white-throated sparrow. We show that, in contrast to the pattern in mammals, male and female Z Chromosomes in these species exhibit highly similar patterns of DNA methylation, which is consistent with weak or absent dosage compensation. We further demonstrate that the epigenetic differences between male and female chicken Z Chromosomes are localized to a few regions, including a previously identified male hypermethylated region 1 (MHM1; CGNC: 80601). We discovered a novel region with elevated male-to-female methylation ratios on the chicken Z Chromosome (male hypermethylated region 2 [MHM2]; CGNC: 80602). The MHMI and MHM2, despite little sequence similarity between them, bear similar molecular features that are likely associated with their functions. We present evidence consistent with female hypomethylation of MHMs and up-regulation of nearby genes. Therefore, despite little methylation differentiation between sexes, extremely localized DNA methylation differences between male and female chicken Z Chromosomes have evolved and affect expression of nearby regions. Our findings offer new insights into epigenetic regulation of gene expression between sexes in female heterogametic systems.