Yu Jia, Sgobio Carmelo, Yang Xuan, Peng Yu, Chen Xi, Sun Lixin, Shim Hoon, Cai Huaibin
Basic Research Center, Institute for Geriatrics and Rehabilitation, Beijing Geriatric Hospital, Beijing 100095, China.
Transgenic Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA.
Ageing Neurodegener Dis. 2022;2(2). doi: 10.20517/and.2022.07. Epub 2022 Apr 27.
Missense mutations of dynactin subunit p150 have been associated with multiple neurodegenerative diseases, including Perry syndrome, characterized by inherited parkinsonism, depression, weight loss, and hypoventilation. The current study investigated how the pathogenic mutant p150 affects the integrity and function of the nigrostriatal dopaminergic (DA) pathway .
Using a tetracycline-controlled transcriptional regulation system, transgenic mouse models were generated with selective overexpression of wild-type, motor neuron disease-related G59S mutant, or Perry syndrome-related G71R mutant human p150 in midbrain DA neurons. A series of behavioral, neuropathological, neurochemical, electrochemical, and biochemical studies were performed on the mice to examine and compare the pathogenic impact of the two mutant p150 on the survival and function of midbrain DA neurons.
Compared with non-transgenic control mice, transgenic mice overexpressing wild-type human p150 showed neither motor phenotypes nor pathological, functional, or biochemical abnormalities of the nigrostriatal DA pathway. Transgenic mice overexpressing G59S mutant p150 displayed weight loss, motor deficits, early-onset defects in dopamine transmission, and early-onset loss of DA neurons and axons. Transgenic mice overexpressing G71R p150 mutant exhibited hyperactivities, impaired motor coordination, early-onset dysfunction of dopamine uptake, and late-onset loss of DA neurons and axons. In addition, overexpression of either G59S or G71R mutant p150 in midbrain DA neurons preferentially downregulated the expression of dopamine transporter at dopaminergic axon terminals. Furthermore, G59S mutant p150 rather than G71R mutant p150 formed aggregates in midbrain DA neurons , and the aggregates trapped dynein/dynactin, co-localized with lysosomes, and upregulated ubiquitination.
These findings demonstrate that selective expression of either G59S or G71R mutant p150 in mouse midbrain DA neurons leads to progressive degeneration of the nigrostriatal DA pathway and indicate that G59S and G71R mutant p150 exhibit differential pathogenic impact on the survival and function of midbrain DA neurons .
动力蛋白激活蛋白亚基p150的错义突变与多种神经退行性疾病相关，包括佩里综合征，其特征为遗传性帕金森症、抑郁、体重减轻和通气不足。本研究调查了致病性突变体p150如何影响黑质纹状体多巴胺能（DA）通路的完整性和功能。
使用四环素调控的转录调节系统，构建转基因小鼠模型，使其在中脑DA神经元中选择性过表达野生型、与运动神经元疾病相关的G59S突变体或与佩里综合征相关的G71R突变体人p150。对这些小鼠进行了一系列行为学、神经病理学、神经化学、电化学和生物化学研究，以检查和比较两种突变体p150对中脑DA神经元存活和功能的致病影响。
与非转基因对照小鼠相比，过表达野生型人p150的转基因小鼠既没有运动表型，也没有黑质纹状体DA通路的病理、功能或生化异常。过表达G59S突变体p150的转基因小鼠出现体重减轻、运动缺陷、多巴胺传递的早期缺陷以及DA神经元和轴突的早期丢失。过表达G71R p150突变体的转基因小鼠表现出活动亢进、运动协调受损、多巴胺摄取的早期功能障碍以及DA神经元和轴突的晚期丢失。此外，在中脑DA神经元中过表达G59S或G71R突变体p150均优先下调多巴胺能轴突终末处多巴胺转运体的表达。此外，G59S突变体p150而非G71R突变体p150在中脑DA神经元中形成聚集体，这些聚集体捕获动力蛋白/动力蛋白激活蛋白，与溶酶体共定位，并上调泛素化。
这些发现表明，在小鼠中脑DA神经元中选择性表达G59S或G71R突变体p150会导致黑质纹状体DA通路的进行性退化，并表明G59S和G71R突变体p150对中脑DA神经元的存活和功能表现出不同的致病影响。
