Graduate School of Health Sciences, Matsumoto University, Matsumoto, Nagano, Japan.
J Physiol. 2022 Jul;600(14):3331-3353. doi: 10.1113/JP282917. Epub 2022 Jun 12.
Histone H3 trimethylation at lysine 27 (H3K27me3) is known to act as a transcriptionally repressive histone modification via heterochromatin formation. In skeletal muscle, it was also reported that H3K27me3 was enriched at the sites transcriptionally activated by exercise, although the role of H3K27me3 in adaptation to exercise is unknown. In this study, using mouse tibialis anterior muscle, we initially determined the genome-wide enrichment of RNA polymerase II and histone H3 trimethylation at lysine 4 (H3K4me3) and H3K27me3 using chromatin immunoprecipitation, followed by sequencing analysis. The loci that were transcriptionally upregulated by a single bout of running exercise were marked by both H3K27me3 and H3K4me3, which were also correlated with the distribution of RNA polymerase II. The genes that were not responsive to exercise exhibited high H3K4me3 occupancy, similar to the upregulated genes but with less H3K27me3. Next, we tested the effects of GSK343, a specific inhibitor of enhancer of zeste homologue 2 (EZH2). Unexpectedly, GSK343 administration enhanced the H3K27me3 occupancy at the target loci, leading to the upregulation of gene responses to acute exercise. Administration of GSK343 also facilitated the phenotypic transformation of type IIb to type IIa fibres and the upregulation of AMPK phosphorylation and levels of heat shock protein 70, pyruvate dehydrogenase kinase 4, peroxisome proliferator-activated receptor γ coactivator-1α and muscle RING finger 1. Furthermore, in contrast to the accelerated adaptation to exercise by GSK343, administration of the EZH1/2 dual inhibitor valemetostat prevented the changes in the aforementioned parameters after exercise training. These results indicate that exercise-induced H3K27me3 plays a key role in inducing exercise-related effects in the skeletal muscle. KEY POINTS: Exercise mediates histone H3 trimethylation at lysine 27 (H3K27me3) at transcriptionally upregulated loci in skeletal muscle, but the role of H3K27me3 in the adaptation of skeletal muscle to exercise training is unclear. Chromatin immunoprecipitation followed by sequencing analysis demonstrated that H3K27me3, in addition to H3K4me3 modifications, is the hallmark of sites showing higher responses to acute exercise. GSK343, a selective inhibitor of the enhancer of zeste homologue 2 (EZH2), enhanced the gene responses to a single bout of exercise and accelerated the adaptive changes during exercise training in association with myonuclear H3K27me3 accumulation. Administration of valemetostat, an EZH1/2 dual inhibitor, repressed myonuclear H3K27me3 accumulation during training and caused a failure of adaptive changes. Exercise-induced H3K27me3 might play a key role in inducing exercise-related effects in skeletal muscle.
组蛋白 H3 赖氨酸 27 三甲基化（H3K27me3）被认为通过异染色质形成作为转录抑制性组蛋白修饰。在骨骼肌中，也有报道称 H3K27me3 在运动激活的转录位点富集，尽管 H3K27me3 在运动适应中的作用尚不清楚。在这项研究中，我们最初使用小鼠胫骨前肌，使用染色质免疫沉淀 followed by sequencing analysis 确定了 RNA 聚合酶 II 和组蛋白 H3 赖氨酸 4 三甲基化（H3K4me3）和 H3K27me3 的全基因组富集。单次跑步运动上调的基因座被 H3K27me3 和 H3K4me3 标记，这与 RNA 聚合酶 II 的分布相关。对运动没有反应的基因表现出高 H3K4me3 占有率，与上调基因相似，但 H3K27me3 较少。接下来，我们测试了 GSK343（EZH2 增强子同源物 2 的特异性抑制剂）的作用。出乎意料的是，GSK343 给药增加了靶基因座处的 H3K27me3 占有率，导致急性运动对基因反应的上调。GSK343 的给药还促进了 IIb 型纤维向 IIa 型纤维的表型转化，并上调了 AMPK 磷酸化和热休克蛋白 70、丙酮酸脱氢酶激酶 4、过氧化物酶体增殖物激活受体 γ 共激活因子 1α 和肌肉 RING 指蛋白 1 的水平。此外，与 GSK343 加速对运动的适应形成对比，EZH1/2 双重抑制剂 valemetostat 的给药阻止了运动训练后上述参数的变化。这些结果表明，运动诱导的 H3K27me3 在诱导骨骼肌中与运动相关的效应中起关键作用。关键点：运动介导了骨骼肌中转录上调基因座的组蛋白 H3 赖氨酸 27 三甲基化（H3K27me3），但 H3K27me3 在骨骼肌对运动训练的适应中的作用尚不清楚。染色质免疫沉淀 followed by sequencing analysis 表明，H3K27me3 除了 H3K4me3 修饰外，还是对急性运动反应更高的基因座的特征。GSK343（EZH2 增强子同源物 2 的选择性抑制剂）增强了单次运动的基因反应，并与肌核 H3K27me3 积累一起加速了运动训练期间的适应性变化。EZH1/2 双重抑制剂 valemetostat 的给药抑制了训练期间肌核 H3K27me3 的积累，并导致适应性变化失败。运动诱导的 H3K27me3 可能在诱导骨骼肌中与运动相关的效应中起关键作用。
