Inserm UMR-S 839, Paris, France; Sorbonne Université, Science and Engineering Faculty, Paris, France; Institut du Fer a Moulin, Paris, France; Departament de Biomedicina, Facultat de Medicina, Institut de Neurociències, Universitat de Barcelona, 08036 Barcelona, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain; Centro de Investigacion Biomedica en Red Sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain.
Inserm UMR-S 839, Paris, France; Sorbonne Université, Science and Engineering Faculty, Paris, France; Institut du Fer a Moulin, Paris, France.
Exp Neurol. 2018 Sep;307:62-73. doi: 10.1016/j.expneurol.2018.05.020. Epub 2018 May 24.
Pyk2 is a Ca-activated non-receptor tyrosine kinase enriched in forebrain neurons and involved in synaptic regulation. Human genetic studies associated PTK2B, the gene coding Pyk2, with risk for Alzheimer's disease (AD). We previously showed that Pyk2 is important for hippocampal function, plasticity, and spine structure. However, its potential role in AD is unknown. To address this question we used human brain samples and 5XFAD mice, an amyloid mouse model of AD expressing mutated human amyloid precursor protein and presenilin1. In the hippocampus of 5XFAD mice and in human AD patients' cortex and hippocampus, Pyk2 total levels were normal. However, Pyk2 Tyr-402 phosphorylation levels, reflecting its autophosphorylation-dependent activity, were reduced in 5XFAD mice at 8 months of age but not 3 months. We crossed these mice with Pyk2 mice to generate 5XFAD animals devoid of Pyk2. At 8 months the phenotype of 5XFAD x Pyk2 double mutant mice was not different from that of 5XFAD. In contrast, overexpression of Pyk2 in the hippocampus of 5XFAD mice, using adeno-associated virus, rescued autophosphorylated Pyk2 levels and improved synaptic markers and performance in several behavioral tasks. Both Pyk2 and 5XFAD mice showed an increase of potentially neurotoxic Src cleavage product, which was rescued by Pyk2 overexpression. Manipulating Pyk2 levels had only minor effects on Aβ plaques, which were slightly decreased in hippocampus CA3 region of double mutant mice and increased following overexpression. Our results show that Pyk2 is not essential for the pathogenic effects of human amyloidogenic mutations in the 5XFAD mouse model. However, the slight decrease in plaque number observed in these mice in the absence of Pyk2 and their increase following Pyk2 overexpression suggest a contribution of this kinase in plaque formation. Importantly, a decreased function of Pyk2 was observed in 5XFAD mice, indicated by its decreased autophosphorylation and associated Src alterations. Overcoming this deficit by Pyk2 overexpression improved the behavioral and molecular phenotype of 5XFAD mice. Thus, our results in a mouse model of AD suggest that Pyk2 impairment may play a role in the symptoms of the disease.
Pyk2 是一种富含于前脑神经元的 Ca 激活非受体酪氨酸激酶，参与突触调节。人类遗传研究将编码 Pyk2 的 PTK2B 基因与阿尔茨海默病（AD）的风险联系起来。我们之前的研究表明，Pyk2 对海马功能、可塑性和棘突结构很重要。然而，它在 AD 中的潜在作用尚不清楚。为了解决这个问题，我们使用了人脑样本和 5XFAD 小鼠，这是一种表达突变人类淀粉样前体蛋白和早老素 1 的 AD 淀粉样蛋白小鼠模型。在 5XFAD 小鼠的海马体以及人类 AD 患者的大脑皮层和海马体中，Pyk2 的总水平正常。然而，反映其自身磷酸化依赖性活性的 Pyk2 Tyr-402 磷酸化水平在 5XFAD 小鼠 8 个月时降低，但在 3 个月时没有降低。我们将这些小鼠与缺乏 Pyk2 的 Pyk2 小鼠杂交，生成 5XFAD 动物的 Pyk2 双突变体。在 8 个月时，5XFAD x Pyk2 双突变体小鼠的表型与 5XFAD 小鼠没有不同。相比之下，使用腺相关病毒在 5XFAD 小鼠的海马体中过表达 Pyk2 可恢复自磷酸化的 Pyk2 水平，并改善多种行为任务中的突触标志物和表现。Pyk2 和 5XFAD 小鼠均显示出潜在神经毒性的 Src 切割产物增加，而过表达 Pyk2 可挽救该产物。操纵 Pyk2 水平对 Aβ 斑块的影响很小，在双突变体小鼠的海马 CA3 区略有减少，而过表达后增加。我们的结果表明，Pyk2 对于 5XFAD 小鼠模型中人类淀粉样蛋白突变的致病作用不是必需的。然而，在缺乏 Pyk2 的情况下，这些小鼠中斑块数量的轻微减少以及过表达后斑块数量的增加表明该激酶在斑块形成中的作用。重要的是，在 5XFAD 小鼠中观察到 Pyk2 的功能降低，这表明其自身磷酸化降低以及相关的 Src 改变。通过 Pyk2 过表达克服这一缺陷可改善 5XFAD 小鼠的行为和分子表型。因此，我们在 AD 小鼠模型中的结果表明，Pyk2 功能障碍可能在疾病症状中起作用。
