Nucleus Type-Specific DNA Methylomics Reveals Epigenetic “Memory” of Prior Adaptation in Skeletal Muscle. Nucleus Type-Specific DNA Methylomics Reveals Epigenetic “Memory” of Prior Adaptation in Skeletal Muscle

Using a mouse model of conditional and inducible in vivo fluorescent myonuclear labeling (HSA-GFP), sorting purification of nuclei, low-input reduced representation bisulfite sequencing (RRBS), and a translatable and reversible model of exercise (progressive weighted wheel running, PoWeR), we provide the first nucleus type-specific epigenetic information on skeletal muscle adaptation and detraining along with whole muscle transcriptomics. Overall design: Human skeletal actin promoter reverse tetracycline transactivator tetracycline response element driven histone 2B green fluorescent protein mice (termed HSA-GFP) were generated to label resident myonuclei at the onset of experimentation. A 4-month-old cohort of these mice were subjected to PoWeR for 8 weeks (6 months old when euthanized, 6M PoW, or “trained”), and another cohort was trained then detrained for 12 weeks to reverse training adaptations (9 months old when euthanized, 9M PoW+DT, or “detrained”); age-matched untrained mice served as controls (6M UT and 9M UT).

本研究借助条件性诱导型体内荧光肌核标记小鼠模型（HSA-GFP）、细胞核分选与纯化技术、低起始量简化代表性亚硫酸氢盐测序（low-input reduced representation bisulfite sequencing, RRBS），以及可转化且可逆的运动模型——渐进式负重转轮运动（progressive weighted wheel running, PoWeR），首次获取了针对骨骼肌适应与脱训练过程的细胞核类型特异性表观遗传信息，并同步获得全肌肉转录组学数据。总体实验设计：我们构建了由人骨骼肌肌动蛋白启动子、反向四环素反式激活因子、四环素反应元件驱动的组蛋白2B绿色荧光蛋白小鼠（命名为HSA-GFP），用于在实验启动时标记驻留肌核。将4月龄的该小鼠队列进行8周PoWeR训练，安乐处死后为6月龄，记为6M PoW，即"训练组"；另一队列先接受训练，随后进行12周脱训练以逆转训练适应性变化，安乐处死后为9月龄，记为9M PoW+DT，即"脱训练组"；以年龄匹配的未训练小鼠作为对照（6M UT和9M UT）。