铁转运相关蛋白在肌萎缩性侧索硬化症转基因鼠脊髓中的表达变化

目的 探讨肌萎缩性侧索硬化症（ALS）转基因鼠脊髓内铁转运相关蛋白表达变化与铁稳态失衡的关联。 方法 选取hSOD1G93A转基因鼠（ALS鼠）和同窝野生型鼠（WT鼠），分别于生后70、95和122 d分离脊髓，每时间点每组各9只实验动物。Western blotting检测脊髓组织内铁转运蛋白二价金属转运蛋白-1（DMT1）、铁转运蛋白-1（FPN1）及调节蛋白铁调节蛋白-1（IRP1）的表达；免疫荧光双重标记检测脊髓腰段前角内细胞共定位情况。 结果 Western blotting显示，与WT鼠比较，各时间点ALS鼠脊髓内DMT1表达均显著降低（P<0.05，P<0.01）；70 d FPN1表达升高（P<0.05），95 d和122 d表达下降（P<0.01）；95 d、122 d IRP1表达降低（P<0.01）。免疫荧光双重标记显示，在70 d WT鼠和ALS鼠腰段脊髓中DMT1主要与β-微管蛋白Ⅲ（β-tubulin Ⅲ）共表达。与WT组相比，95 d ALS鼠脊髓腰段前角神经元内DMT1免疫反应强，而FPN1荧光强度减弱。随疾病进展，DMT1、FPN1与反应性胶质细胞共定位表达增多。IRP1随疾病进展表达强度降低。 结论 随ALS病程进展，发病早期神经元铁转入增加，转出减少，反应性神经胶质细胞铁转运活性增强，参与局部铁稳态失衡及脊髓前角运动神经元进行性丢失。IRP1表达降低，部分参与局部铁代谢调节。

Expressions of iron transport related proteins in the spinal cord of amyotrophic lateral sclerosis transgenic mice

Objective To investigate the relationship between the expressions of iron transport related proteins and the dysregulation of iron homeostasis in the spinal cord of amyotrophic lateral sclerosis(ALS) transgenic mice. Methods The hSOD1G93A transgenic mice (ALS mice) and littermate wild-type mice (WT mice) were selected to separate the spinal cord at day 70, day 95, and day 122 after birth, 9 mice per time point and per group. Western blotting was used to detect the expressions of iron transporter divalent metal transporter-1 (DMT1), ferroportin 1 (FPN1) and regulatory protein iron regulatory protein 1(IRP1) in the spinal cord. Double immunofluorescence labeling was used to detect the co-localization of cells in the ventral horn of lumbar spinal cord. Results Western blotting results showed that compared with WT mice the expressions of DMT1 protein were down-regulated with the disease progression from day 70 to day 122 (P<0.05, P<0.01); FPN1 protein was transiently up-regulated at day 70 (P<0.05), and decline expressions were observed at day 95 and day 122 (P<0.01); IRP1 was down-regulated at day 95 and day 122 (P<0.01). Double immunofluorescence labeling revealed that at day 70, DMT1 co-expressed mainly with β-tubulin Ⅲ both in WT and ALS mice lumbar spinal cord. Compared with the WT group, the DMT1 immunoreactivity in the neurons of the ventral horn lumbar spinal cord of ALS mice was elevated at day 95, while the FPN1 fluorescence intensity was weak. With the disease progression, the co-localization expression of DMT1, FPN1 with reactive glial cells increased. With the disease progresses, the expression of IRP1 decreased. Conclusion With the progression of ALS, iron influx increases and iron outflux decreases in neurons at the early-symptomatic stage of ALS, the activity of iron transport in reactive glial cells is enhanced, which participates in local iron homeostasis imbalance and progressive loss of motor neurons in ventral horn of spinal cord. Decreased expression of IRP1 partly participates in the regulation of local iron metabolism.