1. Academic Validation
  2. 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

  • Life Sci. 2020 Oct 1;258:118243. doi: 10.1016/j.lfs.2020.118243.
Zhen Fan 1 Jing Wu 2 Qiu-Nan Chen 2 An-Kang Lyu 2 Jin-Liang Chen 2 Yue Sun 2 Qiong Lyu 2 Yu-Xing Zhao 2 Ai Guo 2 Zhi-Yin Liao 2 Yun-Fei Yang 2 Shi-Yu Zhu 2 Xu-Shun Jiang 3 Bo Chen 4 Qian Xiao 5
Affiliations

Affiliations

  • 1 Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing 400042, China; Department of Geriatrics, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, Sichuan 610072, China.
  • 2 Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing 400042, China.
  • 3 Department of Nephrology, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing 400042, China.
  • 4 Department of Anesthesiology, Chongqing University Cancer Hospital, Hanyu Road 181, Chongqing 400030, China.
  • 5 Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing 400042, China. Electronic address: xiaoqian@hospital.cqmu.edu.cn.
Abstract

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.

Keywords

Autophagy; Muscle atrophy; P300; Type 2 diabetes.

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