Serbest Gulyeter, Burkhardt Matthew F, Siman Robert, Raghupathi Ramesh, Saatman Kathryn E
Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA.
Neurochem Res. 2007 Dec;32(12):2006-14. doi: 10.1007/s11064-007-9318-9. Epub 2007 Mar 31.
To examine the time course and relative extent of proteolysis of neurofilament and tubulin proteins after traumatic axonal injury (TAI), anesthetized mice were subjected to optic nerve stretch injury. Immunohistochemistry confirmed neurofilament accumulation within axonal swellings at 4, 24, and 72 h postinjury (n = 4 injured and 2 sham per time point). Immunoblotting of optic nerve homogenates (n = 5 injured and 1 sham at 0.5, 4, 24 or 72 h) revealed calpain-mediated spectrin proteolytic fragments after injury. Protein levels for NF68 progressively decreased from 0.5 h to 24 h postinjury, while NF200 and alpha-tubulin levels decreased acutely (0.5-4 h), with a secondary decline at 72 h postinjury. These data demonstrate that diffusely distributed TAI is associated not only with a localized accumulation of neurofilament proteins, but also significant decreases in total cytoskeletal protein levels which may be mediated, in part, by calpains. Protection of the axonal cytoskeleton represents a potential therapeutic target for axonal damage associated with injury or neurodegenerative diseases.
为了研究创伤性轴突损伤（TAI）后神经丝和微管蛋白的蛋白水解的时间进程和相对程度，对麻醉的小鼠进行视神经拉伸损伤。免疫组织化学证实，在损伤后4小时、24小时和72小时，轴突肿胀内有神经丝积聚（每个时间点n = 4只损伤小鼠和2只假手术小鼠）。对视神经匀浆进行免疫印迹分析（在0.5小时、4小时、24小时或72小时时，n = 5只损伤小鼠和1只假手术小鼠），结果显示损伤后有钙蛋白酶介导的血影蛋白蛋白水解片段。NF68的蛋白水平在损伤后0.5小时至24小时逐渐下降，而NF200和α-微管蛋白水平在急性损伤期（0.5 - 4小时）下降，在损伤后72小时出现二次下降。这些数据表明，弥漫性分布的TAI不仅与神经丝蛋白的局部积聚有关，还与总细胞骨架蛋白水平的显著降低有关，这可能部分由钙蛋白酶介导。保护轴突细胞骨架是与损伤或神经退行性疾病相关的轴突损伤的潜在治疗靶点。
