Changes in the function of muscle proteins by oxidative and sugar stress with aging

衰老导致细胞功能下降。骨骼肌的功能受衰老的影响，如萎缩。本项目的目的是证实骨骼肌功能的降低是由衰老引起的蛋白质的非酶修饰引起的。使用4周龄、9月龄和17月龄的大鼠获得以下结果。1.通过蛋白质羰基含量和抗DNP抗体的Western blot检测，骨骼肌中氧化修饰蛋白随增龄而增加。氧化修饰使肌球蛋白ATP酶活性降低。培养的肌管细胞不积累修饰蛋白; 2.骨骼肌中超氧化物歧化酶活性随增龄而降低，谷胱甘肽过氧化物酶活性随增龄而升高; 3.骨骼肌蛋白质的比例随增龄而降低，而非溶酶体蛋白水解率则不随增龄而变化。这些结果表明，随着衰老，SOD活性降低，产生活性氧，修饰骨骼肌蛋白质，蛋白质水解减少，导致氧化修饰蛋白质在骨骼肌中积累，从而影响骨骼肌的收缩活动。

Aging induces the reduced cellular function. The function of skeletal muscle is affected by aging, such as atrophy. The aim of this project is to confirm the reduced function of skeletal muscle is induced by non enzymatic modification of proteins by aging. The following results were obtained using rats of 4 weeks, 9 months and 17 months of age..1.Oxidatively modified proteins in skeletal muscle were increased with aging determined by protein carbonyl content and Western blot using anti-DNP antibody. Oxidative modification decreased the activity of myosin ATPase. Cultured myotube cell was not accumulated modified proteins.2.Superoxide dismutase activity in skeletal muscle was decreased with aging, while glutathione peroxidase activity was increased.3.The rate of skeletal muscle proteins was decreased with aging, however the ratio of no-lysosomal proteolysis was not changed with aging.4.Glycation of skeletal muscle proteins determined by Western blot using anti-AGE antibody showed no changes in aging.These results suggest that reactive oxygen species generated by the reduction of SOD activity with aging modify skeletal muscle proteins, and decreased proteolysis induces the accumulation of oxidatively modified proteins in skeletal muscle, which may affect the contractile activity.