Department of Molecular Toxicology, German Institute of Human Nutrition Potsdam-Rehbrücke, 14558 Nuthetal, Germany.
Department of Molecular Toxicology, German Institute of Human Nutrition Potsdam-Rehbrücke, 14558 Nuthetal, Germany; German Center for Cardiovascular Research (DZHK), 10117 Berlin, Germany.
Exp Gerontol. 2019 Mar;117:45-52. doi: 10.1016/j.exger.2018.10.018. Epub 2018 Oct 24.
The skeletal muscle is a crucial tissue for maintaining whole body homeostasis. Aging seems to have a disruptive effect on skeletal muscle homeostasis including proteostasis. However, how aging specifically impacts slow and fast twitch fiber types remains elusive. Muscle proteostasis is largely maintained by the proteasomal system. Here we characterized the proteasomal system in two different fiber types, using a non-sarcopenic aging model. By analyzing the proteasomal activity and amount, as well as the polyubiquitinated proteins and the level of protein oxidation in Musculus soleus (Sol) and Musculus extensor digitorum longus (EDL), we found that the slow twitch Sol muscle shows an overall higher respiratory and proteasomal activity in young and old animals. However, especially during aging the fast twitch EDL muscle reduces protein oxidation by an increase of antioxidant capacity. Thus, under adaptive non-sarcopenic conditions, the two fibers types seem to have different strategies to avoid age-related changes.
骨骼肌是维持全身内稳态的关键组织。衰老似乎对骨骼肌内稳态产生了破坏性影响，包括蛋白质稳态。然而，衰老如何具体影响慢肌和快肌纤维类型仍不清楚。肌肉蛋白质稳态在很大程度上是由蛋白酶体系统维持的。在这里，我们使用非衰老性衰老模型，对两种不同的纤维类型的蛋白酶体系统进行了表征。通过分析蛋白酶体的活性和数量，以及多聚泛素化蛋白和蛋白质氧化水平，我们发现，在年轻和年老动物中，慢肌比目鱼肌（Sol）表现出整体更高的呼吸和蛋白酶体活性。然而，特别是在衰老过程中，快肌伸趾长肌通过增加抗氧化能力来减少蛋白质氧化。因此，在适应性非衰老条件下，这两种纤维类型似乎有不同的策略来避免与年龄相关的变化。
