Type 2 diabetes-induced overactivation of P300 contributes to skeletal muscle atrophy by inhibiting autophagic flux
Type 2 diabetes-induced overactivation of P300 contributes to skeletal muscle atrophy by inhibiting autophagic flux
复制标题
2 型糖尿病引起的 P300 过度激活通过抑制自噬通量导致骨骼肌萎缩
DOI：
10.1016/j.lfs.2020.118243
复制
发表时间：
2020-10-01
期刊：
影响因子：
6.1
通讯作者：
Xiao, Qian
中科院分区：
文献类型：
--
作者：
Fan, Zhen;Wu, Jing;Xiao, Qian
目的：虽然自噬损伤是肌肉萎缩的一个公认的原因，P300最近已被确定为自噬的重要调节因子，但P300对2型糖尿病（T2 D）中自噬和肌肉萎缩的影响仍未被探索。主要方法：采用蛋白质组学方法，检测了棕榈酸（palmitic acid，PA）处理的肌管和db/db小鼠的磷酸化P300、总P300、乙酰化组蛋白H3、LC 3、p62和肌球蛋白重链的蛋白质水平，以及Atrogin-1和MuRF 1的mRNA水平。使用透射电子显微镜、免疫荧光和mRFP-GFP-LC 3慢病毒转染在细胞中评估自噬通量。测量小鼠的肌肉重量、血糖和握力。进行苏木精和伊红（H&E）染色以确定肌纤维尺寸的变化。为了研究P300对自噬和肌纤维重塑的影响，使用P300特异性抑制剂c646。3-甲基腺嘌呤（3-MA）被用来抑制自噬体的形成，氯喹（CQ）被用来阻断自噬flux.Key发现：磷酸化的P300在响应PA增强其活性，随后抑制自噬流量，导致萎缩相关的形态学和分子的变化在肌管。抑制P300可重建自噬流并改善PA诱导的肌管萎缩。然而，这种作用在很大程度上被自噬抑制剂CQ的共同治疗所消除。在体内的结果表明，抑制P300部分挽救肌肉萎缩在db/db小鼠，伴随着自噬reactivation.Significance：研究结果表明，T2 D诱导的过度激活的P300有助于肌肉萎缩，通过阻断自噬流量。
Aims: Although autophagy impairment is a well-established cause of muscle atrophy and P300 has recently been identified as an important regulator of autophagy, the effects of P300 on autophagy and muscle atrophy in type 2 diabetes (T2D) remain unexplored. We aimed at characterizing the role of P300 in diabetic muscle and its underlying mechanism.Main methods: Protein levels of phosphorylated P300, total P300, acetylated histone H3, LC3, p62 and myosin heavy chain, and mRNA levels of Atrogin-1 and MuRF1 were analyzed in palmitic acid (PA)-treated myotubes and db/db mice. Autophagic flux was assessed using transmission electron microscopy, immunofluorescence and mRFP-GFP-LC3 lentivirus transfection in cells. Muscle weight, blood glucose and grip strength were measured in mice. Hematoxylin and eosin (H&E) staining was performed to determine changes in muscle fiber size. To investigate the effects of P300 on autophagy and myofiber remodeling, a P300 specific inhibitor, c646, was utilized. 3-Methyladenine (3-MA) was utilized to inhibit autophagosomes formation, and chloroquine (CQ) was used to block autophagic flux.Key findings: Phosphorylation of P300 in response to PA enhanced its activity and subsequently suppressed autophagic flux, leading to atrophy-related morphological and molecular changes in myotubes. Inhibition of P300 reestablished autophagic flux and ameliorated PA-induced myotubes atrophy. However, this effect was largely abolished by co-treatment with the autophagy inhibitor CQ. In vivo results demonstrated that inhibition of P300 partially rescued muscle wasting in db/db mice, accompanied with autophagy reactivation.Significance: The findings revealed that T2D-induced overactivation of P300 contributes to muscle atrophy by blocking autophagic flux.