Wang Jianfeng, Liu Jinling, Shao Jingjing, Chen Hongyu, Cui Luyun, Zhang Pei, Yao Yinan, Zhou Jianying, Bao Zhang
Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
Department of Pulmonology, the Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310058 China.
Curr Res Toxicol. 2024 Mar 2;6:100161. doi: 10.1016/j.crtox.2024.100161. eCollection 2024.
Cigarette smoking (CS) causes skeletal muscle dysfunction, leading to sarcopenia and worse prognosis of patients with diverse systemic diseases. Here, we found that CS exposure prevented C2C12 myoblasts proliferation in a dose-dependent manner. Immunoblotting assays verified that CS exposure promoted the expression of cell cycle suppressor protein p21. Furthermore, CS exposure significantly inhibited replication-dependent (RD) histone transcription and caused S phase arrest in the cell cycle during C2C12 proliferation. Mechanistically, CS deregulated the expression levels of Nuclear Protein Ataxia-Telangiectasia Locus (NPAT/p220). Notably, the proteasome inhibitor MG132 was able to reverse the expression of NPAT in myoblasts, implying that the degradation of CS-mediated NPAT is proteasome-dependent. Overexpression of NPAT also rescued the defective proliferation phenotype induced by CS in C2C12 myoblasts. Taken together, we suggest that CS exposure induces NPAT degradation in C2C12 myoblasts and impairs myogenic proliferation through NPAT associated proteasomal-dependent mechanisms. As an application of the proteasome inhibitor MG132 or overexpression of NPAT could reverse the impaired proliferation of myoblasts induced by CS, the recovery of myoblast proliferation may be potential strategies to treat CS-related skeletal muscle dysfunction.
吸烟（CS）会导致骨骼肌功能障碍，进而引发肌肉减少症，并使患有多种全身性疾病的患者预后更差。在此，我们发现暴露于CS会以剂量依赖的方式阻止C2C12成肌细胞增殖。免疫印迹分析证实，暴露于CS会促进细胞周期抑制蛋白p21的表达。此外，暴露于CS会显著抑制复制依赖性（RD）组蛋白转录，并在C2C12增殖过程中导致细胞周期的S期停滞。从机制上讲，CS会使核蛋白共济失调-毛细血管扩张位点（NPAT/p220）的表达水平失调。值得注意的是，蛋白酶体抑制剂MG132能够逆转成肌细胞中NPAT的表达，这意味着CS介导的NPAT降解是蛋白酶体依赖性的。NPAT的过表达也挽救了CS在C2C12成肌细胞中诱导的有缺陷的增殖表型。综上所述，我们认为暴露于CS会诱导C2C12成肌细胞中NPAT降解，并通过NPAT相关的蛋白酶体依赖性机制损害肌源性增殖。由于蛋白酶体抑制剂MG132的应用或NPAT的过表达可以逆转CS诱导的成肌细胞增殖受损，成肌细胞增殖的恢复可能是治疗CS相关骨骼肌功能障碍的潜在策略。
