Muscle H3K27ac landscape remodeling with glucocorticoid steroid regimens

Duchenne muscular dystrophy is caused by genetic defects in the gene encoding dystrophin and leads to progressive muscle degeneration. Glucocorticoid steroids are current mainstay pharmacological regimen to decrease muscle inflammation and prolong the ambulatory period in these patients, but daily intake of glucocorticoids like prednisone and deflazacort causes adverse side effects like osteoporosis, adrenal suppression, insulin resistance and obesity. Intermittent steroid dosing has been proposed as alternative to maintain benefits and limit side effects, but a detailed understanding of the mechanisms underpinning the regimen-specific effects in muscle is still missing. Here we explore how once-daily versus once-weekly prednisone (4 week-long treatment) affect the epigenomic landscape in mdx mouse muscle (genetic model of Duchenne muscular dystrophy; DBA/2J background) through H3K27 acetylation profiles. Overall design: 3 vehicle control samples; 3 once-daily prednisone (1mg/kg i.p.) samples; 3 once-weekly prednisone (1mg/kg i.p.) samples. Each sample is ~10ng immunoprecipitated from the myofiber fraction of quadriceps muscles (2 pooled per mouse) using a rabbit anti-H3K27ac polyclonal antibody (ActiveMotif #39133)

杜氏肌营养不良症（Duchenne muscular dystrophy）由编码肌营养不良蛋白（dystrophin）的基因存在遗传缺陷所致，可引发进行性肌肉变性。糖皮质激素类固醇是当前临床主流药理学治疗方案，能够减轻患者肌肉炎症并延长其自主行走时长，但每日服用泼尼松（prednisone）、地夫可特（deflazacort）等糖皮质激素，会引发骨质疏松、肾上腺抑制、胰岛素抵抗及肥胖等不良反应。有研究提出间歇性类固醇给药方案作为替代策略，以期保留治疗获益同时限制不良反应，但目前仍缺乏对该给药方案在肌肉中特异性作用机制的深入阐释。本研究通过检测H3K27乙酰化（H3K27 acetylation）谱，探究每日一次与每周一次泼尼松（为期4周的给药处理）对mdx小鼠肌肉（杜氏肌营养不良症遗传模型，背景品系为DBA/2J）的表观基因组图谱（epigenomic landscape）的影响。实验整体设计如下：3份载体对照组样本；3份每日一次泼尼松给药组样本（1mg/kg 腹腔注射，i.p.）；3份每周一次泼尼松给药组样本（1mg/kg 腹腔注射，i.p.）。所有样本均取自股四头肌的肌纤维组分，每份样本由2只小鼠的该组分混合制备，使用兔抗H3K27ac多克隆抗体（ActiveMotif #39133）完成约10ng的免疫沉淀。