Differential Cysteine Labeling and Global Label-Free Proteomics Reveals an Altered Metabolic State in Skeletal Muscle Aging

The
molecular mechanisms underlying skeletal muscle aging and associated
sarcopenia have been linked to an altered oxidative status of redox-sensitive
proteins. Reactive oxygen and reactive nitrogen species (ROS/RNS)
generated by contracting skeletal muscle are necessary for optimal
protein function, signaling, and adaptation. To investigate the redox
proteome of aging gastrocnemius muscles from adult and old male mice,
we developed a label-free quantitative proteomic approach that includes
a differential cysteine labeling step. The approach allows simultaneous
identification of up- and downregulated proteins between samples in
addition to the identification and relative quantification of the
reversible oxidation state of susceptible redox cysteine residues.
Results from muscles of adult and old mice indicate significant changes
in the content of chaperone, glucose metabolism, and cytoskeletal
regulatory proteins, including Protein DJ-1, cAMP-dependent protein
kinase type II, 78 kDa glucose regulated protein, and a reduction
in the number of redox-responsive proteins identified in muscle of
old mice. Results demonstrate skeletal muscle aging causes a reduction
in redox-sensitive proteins involved in the generation of precursor
metabolites and energy metabolism, indicating a loss in the flexibility
of the redox energy response. Data is available via ProteomeXchange
with identifier PXD001054.

骨骼肌衰老及其相关肌少症的分子机制，与氧化还原敏感蛋白的氧化状态改变密切相关。由收缩状态的骨骼肌产生的活性氧与活性氮物种（ROS/RNS），对于维持最佳蛋白质功能、信号转导及适应性反应是必需的。为探究成年与老年雄性小鼠腓肠肌的氧化还原蛋白质组，我们开发了一种包含差异化半胱氨酸标记步骤的无标记定量蛋白质组学方法。该方法可同时鉴定不同样本间表达上调与下调的蛋白质，还能对易受氧化还原调控的半胱氨酸残基的可逆氧化状态进行鉴定与相对定量。对成年与老年小鼠肌肉的分析结果显示，伴侣蛋白、糖代谢及细胞骨架调控蛋白的含量发生了显著变化，其中包括DJ-1蛋白、cAMP依赖型蛋白激酶II型、78 kDa葡萄糖调节蛋白；且老年小鼠肌肉中可被氧化还原调控的蛋白质数量有所减少。研究结果表明，骨骼肌衰老会导致参与前体代谢物生成与能量代谢的氧化还原敏感蛋白水平降低，提示氧化还原能量应答的灵活性出现丧失。相关数据集可通过ProteomeXchange获取，标识符为PXD001054。