Functional enhancement and protection of dopaminergic terminals by RAB3B overexpression
Functional enhancement and protection of dopaminergic terminals by RAB3B overexpression
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DOI：
10.1073/pnas.0912193106
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发表时间：
2009-12-29
影响因子：
11.1
通讯作者：
Isacson, Ole
中科院分区：
文献类型：
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作者：
Chung, Chee Yeun;Koprich, James B.;Isacson, Ole
在帕金森病(PD)中，黑质(SN，A9)中的多巴胺(DA)神经元与腹侧被盖区(VTA，A10)中相邻的DA神经元相比，尤其脆弱。在这里，我们表明在大鼠和人类中，RAB3亚型RAB3B在A10神经元中的表达水平高于A9神经元。RAB3是一种高度富含在突触小泡中的单体GTPase蛋白，参与突触小泡的运输和突触传递，其异常与包括帕金森病在内的多种神经退行性疾病有关。这些发现促使我们进一步研究RAB3B在体外和体内的生物学和神经保护能力。RAB3B在人多巴胺能BE(2)-M17细胞中的过表达增加了神经递质含量、[(3)H]多巴胺摄取和突触前蛋白水平。AAV介导的RAB3B在大鼠黑质A9 DA神经元中的过表达增加了纹状体多巴胺含量、突触小泡的数量和大小以及突触前蛋白的水平，证实了体外的研究结果。注射L多巴后细胞外多巴胺代谢产物DOPAC的测定支持RAB3B在增强突触终末的多巴胺存储能力中的作用。在BE(2)-M17细胞中过表达RAB3B对体外模拟PD方面的毒素具有保护作用，包括氧化应激源6-羟基多巴胺(6-OHDA)和蛋白酶体抑制剂MG-132。此外，RAB3B在大鼠黑质中的过表达既保护了A9 DA神经元，又导致了6-OHDA逆行损毁PD模型的行为改善。这些结果表明，RAB3B改善了突触前终末的多巴胺处理和储存能力，并为脆弱的DA神经元提供了保护。
In Parkinson's disease (PD), dopaminergic (DA) neurons in the substantia nigra (SN, A9) are particularly vulnerable, compared to adjacent DA neurons within the ventral tegmental area (VTA, A10). Here, we show that in rat and human, one RAB3 isoform, RAB3B, has higher expression levels in A10 compared to A9 neurons. RAB3 is a monomeric GTPase protein that is highly enriched in synaptic vesicles and is involved in synaptic vesicle trafficking and synaptic transmission, disturbances of which have been implicated in several neurodegenerative diseases, including PD. These findings prompted us to further investigate the biology and neuroprotective capacity of RAB3B both in vitro and in vivo. RAB3B overexpression in human dopaminergic BE (2)-M17 cells increased neurotransmitter content, [(3)H] dopamine uptake, and levels of presynaptic proteins. AAV-mediated RAB3B overexpression in A9 DA neurons of the rat SN increased striatal dopamine content, number and size of synaptic vesicles, and levels of the presynaptic proteins, confirming in vitro findings. Measurement of extracellular DOPAC, a dopamine metabolite, following L-DOPA injection supported a role for RAB3B in enhancing the dopamine storage capacity of synaptic terminals. RAB3B overexpression in BE (2)-M17 cells was protective against toxins that simulate aspects of PD in vitro, including an oxidative stressor 6-hydroxydopamine (6-OHDA) and a proteasome inhibitor MG-132. Furthermore, RAB3B overexpression in rat SN both protected A9 DA neurons and resulted in behavioral improvement in a 6-OHDA retrograde lesion model of PD. These results suggest that RAB3B improves dopamine handling and storage capacity at presynaptic terminals, and confers protection to vulnerable DA neurons.