Laboratory of Cellular Metabolism, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland; Military Institute of Hygiene and Epidemiology, Warsaw, Poland.
Laboratory of Cellular Metabolism, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland.
Biochim Biophys Acta Mol Basis Dis. 2019 Jun 1;1865(6):1138-1151. doi: 10.1016/j.bbadis.2019.01.002. Epub 2019 Jan 24.
Pathophysiology of Duchenne Muscular Dystrophy (DMD) is still elusive. Although progressive wasting of muscle fibres is a cause of muscle deterioration, there is a growing body of evidence that the triggering effects of DMD mutation are present at the earlier stage of muscle development and affect myogenic cells. Among these abnormalities, elevated activity of P2X7 receptors and increased store-operated calcium entry myoblasts have been identified in mdx mouse. Here, the metabotropic extracellular ATP/UTP-evoked response has been investigated. Sensitivity to antagonist, effect of gene silencing and cellular localization studies linked these elevated purinergic responses to the increased expression of P2Y2 but not P2Y4 receptors. These alterations have physiological implications as shown by reduced motility of mdx myoblasts upon treatment with P2Y2 agonist. However, the ultimate increase in intracellular calcium in dystrophic cells reflected complex alterations of calcium homeostasis identified in the RNA seq data and with significant modulation confirmed at the protein level, including a decrease of Gq11 subunit α, plasma membrane calcium ATP-ase, inositol-2,4,5-trisphosphate-receptor proteins and elevation of phospholipase Cβ, sarco-endoplamatic reticulum calcium ATP-ase and sodium‑calcium exchanger. In conclusion, whereas specificity of dystrophic myoblast excitation by extracellular nucleotides is determined by particular receptor overexpression, the intensity of such altered response depends on relative activities of downstream calcium regulators that are also affected by Dmd mutations. Furthermore, these phenotypic effects of DMD emerge as early as in undifferentiated muscle. Therefore, the pathogenesis of DMD and the relevance of current therapeutic approaches may need re-evaluation.
杜氏肌营养不良症（DMD）的病理生理学仍然难以捉摸。尽管肌肉纤维的进行性消耗是肌肉恶化的原因，但越来越多的证据表明，DMD 突变的触发效应早在肌肉发育的早期阶段就存在，并影响肌源性细胞。在这些异常中，在 mdx 小鼠中已经鉴定出 P2X7 受体的活性升高和储存操纵的钙内流成肌细胞。在这里，研究了代谢型细胞外 ATP/UTP 诱发反应。对拮抗剂的敏感性、基因沉默的影响以及细胞定位研究将这些升高的嘌呤能反应与 P2Y2 而不是 P2Y4 受体的表达增加联系起来。这些改变具有生理学意义，如 mdx 成肌细胞用 P2Y2 激动剂处理后运动能力降低所示。然而，在 RNA 测序数据中确定的钙稳态的复杂变化以及在蛋白质水平上得到证实的显著调节反映了在营养不良细胞中的细胞内钙最终增加，包括 Gq11 亚基 α、质膜钙 ATP 酶、肌醇-2,4,5-三磷酸受体蛋白的减少和磷脂酶 Cβ、肌浆内质网钙 ATP 酶和钠钙交换体的升高。总之，尽管细胞外核苷酸对营养不良肌母细胞的激发特异性由特定受体的过度表达决定，但这种改变反应的强度取决于下游钙调节剂的相对活性，而这些调节剂也受到 Dmd 突变的影响。此外，DMD 的这些表型效应早在未分化的肌肉中就出现了。因此，DMD 的发病机制和当前治疗方法的相关性可能需要重新评估。
