Table_9_Genome-Wide DNA Methylation and Hydroxymethylation Changes Revealed Epigenetic Regulation of Neuromodulation and Myelination in Yak Hypothalamus.XLSX

Both 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are important epigenetic modifications in neurodevelopment. However, there is little research examining the genome-wide patterns of 5mC and 5hmC in brain regions of animals under natural high-altitude conditions. We used oxidative reduced representation bisulfite sequencing (oxRRBS) to determine the 5mC and 5hmC sites in the brain, brainstem, cerebellum, and hypothalamus of yak and cattle. We reported the first map of genome-wide DNA methylation and hydroxymethylation in the brain, brainstem, cerebellum, and hypothalamus of yak (living at high altitudes) and cattle. Overall, we found striking differences in 5mC and 5hmC between the hypothalamus and other brain regions in both yak and cattle. Genome-wide profiling revealed that 5mC level decreased and 5hmC level increased in the hypothalamus than in other regions. Furthermore, we identified differentially methylated regions (DMRs) and differentially hydroxymethylated regions (DhMRs), most of which overlapped with each other. Interestingly, transcriptome results for these brain regions also showed distinctive gene levels in the hypothalamus. Finally, differentially expressed genes (DEGs) regulated by DMRs and DhMRs may play important roles in neuromodulation and myelination. Overall, our results suggested that mediation of 5mC and 5hmC on epigenetic regulation may broadly impact the development of hypothalamus and its biological functions.

5-甲基胞嘧啶（5mC）与5-羟甲基胞嘧啶（5hmC）均为神经发育过程中的关键表观遗传修饰。然而，针对自然高海拔条件下动物大脑区域中5mC和5hmC的基因组模式的研究却寥寥无几。本研究采用氧化还原代表性亚硫酸氢盐测序（oxRRBS）技术，对牦牛和牛的大脑、脑干、小脑和下丘脑中的5mC和5hmC位点进行了测定。我们首次描绘了牦牛（生活在高海拔地区）和牛的大脑、脑干、小脑和下丘脑的基因组DNA甲基化和羟甲基化图谱。总体而言，我们在牦牛和牛的下丘脑与其他大脑区域之间发现了显著的5mC和5hmC差异。全基因组分析揭示，下丘脑中的5mC水平降低，而5hmC水平升高。此外，我们还鉴定出差异甲基化区域（DMRs）和差异羟甲基化区域（DhMRs），其中大部分区域相互重叠。有趣的是，这些大脑区域的转录组结果也显示出下丘脑中独特的基因表达水平。最终，受DMRs和DhMRs调控的差异表达基因（DEGs）可能在神经调节和髓鞘形成中发挥重要作用。总体而言，我们的研究结果表明，5mC和5hmC在表观遗传调控中的介导作用可能广泛影响下丘脑的发育及其生物学功能。