Microtubules have been identified as a powerful target for augmenting regeneration of injured adult axons in the central nervous system. Drugs that stabilize microtubules have shown some promise, but there are concern...Microtubules have been identified as a powerful target for augmenting regeneration of injured adult axons in the central nervous system. Drugs that stabilize microtubules have shown some promise, but there are concerns that abnormally stabilizing microtubules may have only limited benefits for regeneration, while at the same time may be detrimental to the normal work that microtubules perform for the axon. Kinesin-5 （also called kifl I or EgS）, a molecular motor protein best known for its crucial role in mitosis, acts as a brake on microtubule movements by other motor proteins in the axon. Drugs that inhibit kinesin-5, originally developed to treat cancer, result in greater mobility of microtubules in the axon and an overall shift in the forces on the microtubule array. As a result, the axon grows faster, retracts less, and more readily enters environments that are inhibitory to axonal regeneration. Thus, drugs that inhibit kinesin-5 offer a novel microtubule-based means to boost axonal regeneration without the concerns that accompany abnormal stabilization of the microtubule array. Even so, inhibiting kinesin-5 is not without its own caveats, such as potential problems with navigation of the regenerating axon to its target, as well as morphological effects on dendrites that could affect learning and memory if the drugs reach the brain.展开更多
目的探讨驱动蛋白家族成员5A(kinesin family member 5A,KIF5A)介导的溶酶体功能损伤在镉神经毒性中的作用。方法以原代培养的SPF级C57BL/6J小鼠皮层神经元为模型,分为对照组和镉暴露组。检测氯化镉暴露24 h后皮层神经元的半数抑制浓度(...目的探讨驱动蛋白家族成员5A(kinesin family member 5A,KIF5A)介导的溶酶体功能损伤在镉神经毒性中的作用。方法以原代培养的SPF级C57BL/6J小鼠皮层神经元为模型,分为对照组和镉暴露组。检测氯化镉暴露24 h后皮层神经元的半数抑制浓度(IC_(50))。进一步用1、2、3μmol/L氯化镉处理神经元24 h,检测细胞存活率、神经元分化和溶酶体功能。RT-qPCR和Western blot检测KIF5A mRNA和蛋白的表达。腺病毒过表达KIF5A检测镉暴露后神经元的溶酶体功能、分化及细胞存活率。结果神经元暴露氯化镉24 h的半数抑制浓度IC_(50)为2.9μmol/L。与对照组相比,2、3μmol/L镉暴露24 h后神经元细胞活力受到抑制(P<0.01),突起生长的总长度和分枝点数目显著减少(P<0.01)。此外,与对照组相比,2、3μmol/L氯化镉处理后显著抑制神经元溶酶体组织蛋白酶B(cathepsin B,CTSB)的活性和改变其酸性环境(P<0.01),但是对组织蛋白酶D(cathepsin D,CTSD)活性没有影响。镉暴露后KIF5A的mRNA及蛋白表达显著降低(P<0.01)。过表达KIF5A可以显著改善镉暴露对神经元组织蛋白酶活性CTSB的抑制、稳定镉暴露造成的溶酶体pH值改变,拮抗镉暴露对神经元细胞活力及突起生长的抑制作用(P<0.01)。结论镉暴露显著减少神经元中KIF5A蛋白的表达,从而损伤溶酶体功能,抑制神经元细胞活力及突起生长。展开更多
基金discussed here on kinesin-5 inhibition as a means for augmenting nerve regeneration after injury was supported mainly by grants from the Craig H.Neilsen Foundation
文摘Microtubules have been identified as a powerful target for augmenting regeneration of injured adult axons in the central nervous system. Drugs that stabilize microtubules have shown some promise, but there are concerns that abnormally stabilizing microtubules may have only limited benefits for regeneration, while at the same time may be detrimental to the normal work that microtubules perform for the axon. Kinesin-5 （also called kifl I or EgS）, a molecular motor protein best known for its crucial role in mitosis, acts as a brake on microtubule movements by other motor proteins in the axon. Drugs that inhibit kinesin-5, originally developed to treat cancer, result in greater mobility of microtubules in the axon and an overall shift in the forces on the microtubule array. As a result, the axon grows faster, retracts less, and more readily enters environments that are inhibitory to axonal regeneration. Thus, drugs that inhibit kinesin-5 offer a novel microtubule-based means to boost axonal regeneration without the concerns that accompany abnormal stabilization of the microtubule array. Even so, inhibiting kinesin-5 is not without its own caveats, such as potential problems with navigation of the regenerating axon to its target, as well as morphological effects on dendrites that could affect learning and memory if the drugs reach the brain.
