Ammonia induces calpain-dependent cleavage of CRMP-2 during neurite degeneration in primary cultured neurons
Ammonia induces calpain-dependent cleavage of CRMP-2 during neurite degeneration in primary cultured neurons
复制标题
原代培养神经元神经突变性过程中氨诱导 CRMP-2 的钙蛋白酶依赖性裂解
DOI：
10.18632/aging.102053
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发表时间：
2019-07-15
期刊：
影响因子：
5.2
通讯作者：
Tan, Minghui
中科院分区：
文献类型：
--
作者：
Cai, Zhenbin;Zhu, Xiaonan;Tan, Minghui
中枢神经系统中的高氨血症会导致终末性细胞丢失，从而导致神经元不可逆转的损伤。轴突变性是导致神经细胞死亡的主要事件，尤其是在高氨血症的情况下，其机制尚不清楚。在这里，我们发现，氨诱导培养的小脑颗粒神经元轴突变性。由此产生的神经元形态改变、突起破裂和细胞骨架解体导致细胞死亡。Calcein和Fluo-4染色显示氨引起细胞内钙离子紊乱。随后激活的Calain裂解了CRMP-2，这是一种微管组装蛋白。在氨水处理下，抑制caspase或GSK-3，而不是抑制caspase或GSK-3，抑制CRMP-2的裂解并逆转轴突变性。暴露于氨可使小的兴奋性突触后电流的幅度和频率降低，而抑制钙激活酶则可使其恢复。这些数据表明，氨水平升高可能通过异常的钙内流和钙蛋白酶依赖的CRMP-2裂解导致神经元功能障碍，导致突触传递异常、细胞骨架崩溃和轴突变性。
Hyperammonemia in the CNS induces irreversible damages to neurons due to ultimate cell loss. Neurite degeneration, a primary event that leads to neuronal cell death, remains less elucidated especially in hyperammonemia circumstances. Here, we found that the administration of ammonia induced neurite degeneration in cultured cerebellar granule neurons. The resulting altered neuronal morphology, rupture of neurites, and disassembly of the cytoskeleton led to cell death. Calcein and Fluo-4 staining revealed that ammonia induced intracellular calcium dysregulation. Subsequently activated calpain cleaved CRMP-2, a microtubule assembly protein. Pharmacologically inhibition of calpain, but not caspases or GSK-3, suppressed the cleavage of CRMP-2 and reversed neurite degeneration under ammonia treatment. Exposure to ammonia decreased whereas inhibition of calpain restored the amplitude and frequency of miniature excitatory postsynaptic currents. These data suggest a mechanism by which elevated ammonia level may induce neuronal dysfunction via abnormal calcium influx and calpain-dependent CRMP-2 cleavage, leading to abnormal synaptic transmission, cytoskeletal collapse, and neurite degeneration.