Abstract：
Skeletal muscle injury affects the quality of life in many pathologies, including volumetric muscle loss, contusion injury, and aging. We hypothesized that the nicotinamide phosphoribosyltransferase (Nampt) activator P7C3 improves muscle repair following injury. In the present study, we tested the effect of P7C3 (1-anilino-3-(3,6-dibromocarbazol-9-yl) propan-2-ol) on chemically induced muscle injury. Muscle injury was induced by injecting 50 µL 1.2% barium chloride (BaCl2) into the tibialis anterior (TA) muscle in C57Bl/6J wild-type male mice. Mice were then treated with either 10 mg/kg body weight of P7C3 or Vehicle intraperitoneally for 7 days and assessed for histological, biochemical, and molecular changes. In the present study, we show that the acute BaCl2-induced TA muscle injury was robust and the P7C3-treated mice displayed a significant increase in the total number of myonuclei and blood vessels, and decreased serum CK activity compared with vehicle-treated mice. The specificity of P7C3 was evaluated using Nampt+/- mice, which did not display any significant difference in muscle repair capacity among treated groups. RNA-sequencing analysis of the injured TA muscles displayed 368 and 212 genes to be exclusively expressed in P7C3 and Veh-treated mice, respectively. There was an increase in the expression of genes involved in cellular processes, inflammatory response, angiogenesis, and muscle development in P7C3 versus Veh-treated mice. Conversely, there is a decrease in muscle structure and function, myeloid cell differentiation, glutathione, and oxidation-reduction, drug metabolism, and circadian rhythm signaling pathways. Chromatin immunoprecipitation-quantitative polymerase chain reaction (qPCR) and reverse transcription-qPCR analyses identified increased Pax7, Myf5, MyoD, and Myogenin expression in P7C3-treated mice. Increased histone lysine (H3K) methylation and acetylation were observed in P7C3-treated mice, with significant upregulation in inflammatory markers. Moreover, P7C3 treatment significantly increased the myotube fusion index in the BaCl2-injured human skeletal muscle in vitro. P7C3 also inhibited the lipopolysaccharide-induced inflammatory response and mitochondrial membrane potential of RAW 264.7 macrophage cells. Overall, we demonstrate that P7C3 activates muscle stem cells and enhances muscle injury repair with increased angiogenesis.
摘要：
骨骼肌损伤影响许多病理的生活质量，包括体积肌肉损失，挫伤,和衰老。我们假设烟酰胺磷酸核糖基转移酶（Nampt）激活剂P7C3可改善损伤后的肌肉修复。在本研究中,我们测试了P7C3（1-苯胺基-3-（3,6-二溴咔唑-9-基）丙-2-醇）对化学诱导的肌肉损伤的影响。通过在C57Bl/6J野生型雄性小鼠的胫骨前肌（TA）中注射50µL1.2％氯化钡（BaCl2）来诱导肌肉损伤。然后用10mg/kg体重的P7C3或媒介物腹膜内治疗小鼠7天，并评估组织学，生物化学，和分子变化。在本研究中,我们表明，急性BaCl2诱导的TA肌肉损伤是强大的，P7C3处理的小鼠显示出肌核和血管总数的显着增加，与媒介物处理的小鼠相比，血清CK活性降低。使用Nampt+/-小鼠评估P7C3的特异性，治疗组之间的肌肉修复能力没有显着差异。受损TA肌肉的RNA测序分析显示，368和212个基因仅在P7C3和Veh处理的小鼠中表达。分别。参与细胞过程的基因表达增加，炎症反应，血管生成,和P7C3与Veh处理的小鼠的肌肉发育。相反，肌肉结构和功能下降，骨髓细胞分化，谷胱甘肽,和氧化还原，药物代谢，和昼夜节律信号通路。染色质免疫沉淀-定量聚合酶链反应（qPCR）和逆转录-qPCR分析发现Pax7，Myf5，MyoD，和P7C3处理的小鼠中的肌原蛋白表达。在P7C3处理的小鼠中观察到组蛋白赖氨酸（H3K）甲基化和乙酰化增加，炎症标志物显著上调。此外，P7C3处理在体外显著增加BaCl2损伤的人骨骼肌中的肌管融合指数。P7C3还抑制脂多糖诱导的RAW264.7巨噬细胞的炎症反应和线粒体膜电位。总的来说,我们证明了P7C3激活肌肉干细胞并通过增加血管生成来增强肌肉损伤修复。
