Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas - UNICAMP, Campinas, SP, Brazil.
Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas - UNICAMP, Campinas, SP, Brazil; Department of Structural and Functional Biology, Institute of Biology, State University of Campinas - UNICAMP, Campinas, SP, Brazil.
Toxicol Appl Pharmacol. 2020 Sep 1;402:115119. doi: 10.1016/j.taap.2020.115119. Epub 2020 Jul 1.
Bites by viperid snakes belonging to Bothrops genus produce fast and intense local edema, inflammation, bleeding and myonecrosis. In this study, we investigated the role of Myogenic Regulatory Factors (MRFs: MyoD; Myog), negatively regulated by GDF-8 (Myostatin), and ubiquitin-proteasome system pathway (UPS: MuRF-1; Fbx-32) in gastrocnemius muscle regeneration after Bothrops jararacussu snake venom (Bjussu) or its isolated phospholipase A myotoxins, BthTx-I (Lys-49 PLA) and BthTx-II (Asp-49 PLA) injection. Male Swiss mice received a single intra-gastrocnemius injection of crude Bjussu, at a dose/volume of 0.83 mg/kg/20 μl, and BthTx-I or BthTx-II, at a dose/volume of 2.5 mg/kg/20 μl. Control mice (Sham) received an injection of sterile saline solution (NaCl 0.9%; 20 μl). At 24, 48, 72 and 96 h post injection, right gastrocnemius was collected for protein expression analyses. Based on the temporal expressional dynamics of MyoD, Myog and GDF-8/Myostatin, it was possible to propose that the myogenesis pathway was impacted most badly by BthTx-II followed by BthTx-I and lastly by B. jararacussu venom, thus suggesting that catalytic activity has likely inhibitory role on the satellite cells-mediated reparative myogenesis pathway. Inversely, the catalytic activity seems to be not a determinant for the activation of proteins ubiquitination by MuRF-1 and Fbx-32/Atrogin-1 E3 proteasome ligases, given proteolysis pathway through UPS was activated neither after Bjussu, nor after BthTx-II, but just after the catalytically-inactive BthTx-I Lys-49 PLA-homologue exposure. The findings of this study disclose interesting perspective for further mechanistic studies about pathways that take part in the atrophy and repair after permanent damage induced by bothropic snakebites.
属于矛头蝮属的毒蛇咬伤会迅速且剧烈地引起局部水肿、炎症、出血和肌坏死。在这项研究中，我们研究了肌肉生成调节因子（MRFs：MyoD；Myog）的作用，这些因子受 GDF-8（肌肉生长抑制素）和泛素-蛋白酶体系统途径（UPS：MuRF-1；Fbx-32）的负调控，用于研究巴西矛头蝮蛇毒液（Bjussu）或其分离的磷脂酶 A 肌毒素 Bjussu、BthTx-I（Lys-49 PLA）和 BthTx-II（Asp-49 PLA）注射后腓肠肌再生。雄性瑞士小鼠接受单次腓肠肌内注射粗制 Bjussu，剂量/体积为 0.83mg/kg/20μl，以及 BthTx-I 或 BthTx-II，剂量/体积为 2.5mg/kg/20μl。对照小鼠（Sham）接受无菌生理盐水溶液（NaCl 0.9%；20μl）注射。在注射后 24、48、72 和 96 小时，收集右侧腓肠肌进行蛋白质表达分析。基于 MyoD、Myog 和 GDF-8/Myostatin 的时间表达动态，可以提出 Myogenesis 途径受到 BthTx-II 的影响最大，其次是 BthTx-I，最后是 B. jararacussu 毒液，因此表明催化活性可能对卫星细胞介导的修复性肌肉生成途径具有抑制作用。相反，鉴于 UPS 通路的蛋白水解途径既不在 Bjussu 后，也不在 BthTx-II 后被激活，只是在催化失活的 BthTx-I Lys-49 PLA 同源物暴露后被激活，因此催化活性似乎不是 MuRF-1 和 Fbx-32/Atrogin-1 E3 蛋白酶体连接酶激活蛋白泛素化的决定因素。本研究的结果揭示了关于永久性损伤引起的萎缩和修复过程中参与的途径的进一步机制研究的有趣视角。
