HGF/MET信号通路减弱可能导致阿尔茨海默病小鼠模型中的突触病理学改变。

Reduced HGF/MET Signaling May Contribute to the Synaptic Pathology in an Alzheimer's Disease Mouse Model.

作者信息

Wei Jing, Ma Xiaokuang, Nehme Antoine, Cui Yuehua, Zhang Le, Qiu Shenfeng

机构信息

Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States.

出版信息

Front Aging Neurosci. 2022 Jul 12;14:954266. doi: 10.3389/fnagi.2022.954266. eCollection 2022.

Abstract

Alzheimer's disease (AD) is a neurodegenerative disorder strongly associates with aging. While amyloid plagues and neurofibrillary tangles are pathological hallmarks of AD, recent evidence suggests synaptic dysfunction and physical loss may be the key mechanisms that determine the clinical syndrome and dementia onset. Currently, no effective therapy prevents neuropathological changes and cognitive decline. Neurotrophic factors and their receptors represent novel therapeutic targets to treat AD and dementia. Recent clinical literature revealed that MET receptor tyrosine kinase protein is reduced in AD patient's brain. Activation of MET by its ligand hepatocyte growth factor (HGF) initiates pleiotropic signaling in the developing brain that promotes neurogenesis, survival, synaptogenesis, and plasticity. We hypothesize that if reduced MET signaling plays a role in AD pathogenesis, this might be reflected in the AD mouse models and as such provides opportunities for mechanistic studies on the role of HGF/MET in AD. Examining the 5XFAD mouse model revealed that MET protein exhibits age-dependent progressive reduction prior to overt neuronal pathology, which cannot be explained by indiscriminate loss of total synaptic proteins. In addition, genetic ablation of MET protein in cortical excitatory neurons exacerbates amyloid-related neuropathology in 5XFAD mice. We further found that HGF enhances prefrontal layer 5 neuron synaptic plasticity measured by long-term potentiation (LTP). However, the degree of LTP enhancement is significantly reduced in 5XFAD mice brain slices. Taken together, our study revealed that early reduction of HGF/MET signaling may contribute to the synaptic pathology observed in AD.

摘要

阿尔茨海默病(AD)是一种与衰老密切相关的神经退行性疾病。虽然淀粉样斑块和神经原纤维缠结是AD的病理标志,但最近的证据表明,突触功能障碍和突触丧失可能是决定临床综合征和痴呆症发病的关键机制。目前,尚无有效的疗法可预防神经病理变化和认知能力下降。神经营养因子及其受体是治疗AD和痴呆症的新型治疗靶点。最近的临床文献显示,AD患者大脑中的MET受体酪氨酸激酶蛋白减少。其配体肝细胞生长因子(HGF)激活MET会在发育中的大脑中引发多效性信号传导,促进神经发生、存活、突触形成和可塑性。我们假设,如果MET信号减少在AD发病机制中起作用,这可能会在AD小鼠模型中得到体现,从而为研究HGF/MET在AD中的作用机制提供机会。对5XFAD小鼠模型的研究表明,在明显的神经元病理变化出现之前,MET蛋白呈现出随年龄增长的渐进性减少,这不能用总突触蛋白的无差别丧失来解释。此外,皮质兴奋性神经元中MET蛋白的基因敲除会加剧5XFAD小鼠的淀粉样相关神经病理变化。我们进一步发现,HGF可增强通过长时程增强(LTP)测量的前额叶第5层神经元的突触可塑性。然而,在5XFAD小鼠脑片中,LTP增强的程度显著降低。综上所述,我们的研究表明,HGF/MET信号的早期减少可能导致AD中观察到的突触病理变化。

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