DNase II 缺陷诱导的神经元双链 DNA 积累促使 tau 磷酸化和神经退行性变。

Neuronal double-stranded DNA accumulation induced by DNase II deficiency drives tau phosphorylation and neurodegeneration.

机构信息

State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China.

University of Chinese Academy of Sciences, Beijing, 100049, China.

出版信息

Transl Neurodegener. 2024 Aug 2;13(1):39. doi: 10.1186/s40035-024-00427-8.

DOI:10.1186/s40035-024-00427-8

PMID:39095921

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC11295666/

Abstract

BACKGROUND

Deoxyribonuclease 2 (DNase II) plays a key role in clearing cytoplasmic double-stranded DNA (dsDNA). Deficiency of DNase II leads to DNA accumulation in the cytoplasm. Persistent dsDNA in neurons is an early pathological hallmark of senescence and neurodegenerative diseases including Alzheimer's disease (AD). However, it is not clear how DNase II and neuronal cytoplasmic dsDNA influence neuropathogenesis. Tau hyperphosphorylation is a key factor for the pathogenesis of AD. The effect of DNase II and neuronal cytoplasmic dsDNA on neuronal tau hyperphosphorylation remains unclarified.

METHODS

The levels of neuronal DNase II and dsDNA in WT and Tau-P301S mice of different ages were measured by immunohistochemistry and immunolabeling, and the levels of DNase II in the plasma of AD patients were measured by ELISA. To investigate the impact of DNase II on tauopathy, the levels of phosphorylated tau, phosphokinase, phosphatase, synaptic proteins, gliosis and proinflammatory cytokines in the brains of neuronal DNase II-deficient WT mice, neuronal DNase II-deficient Tau-P301S mice and neuronal DNase II-overexpressing Tau-P301S mice were evaluated by immunolabeling, immunoblotting or ELISA. Cognitive performance was determined using the Morris water maze test, Y-maze test, novel object recognition test and open field test.

RESULTS

The levels of DNase II were significantly decreased in the brains and the plasma of AD patients. DNase II also decreased age-dependently in the neurons of WT and Tau-P301S mice, along with increased dsDNA accumulation in the cytoplasm. The DNA accumulation induced by neuronal DNase II deficiency drove tau phosphorylation by upregulating cyclin-dependent-like kinase-5 (CDK5) and calcium/calmodulin activated protein kinase II (CaMKII) and downregulating phosphatase protein phosphatase 2A (PP2A). Moreover, DNase II knockdown induced and significantly exacerbated neuron loss, neuroinflammation and cognitive deficits in WT and Tau-P301S mice, respectively, while overexpression of neuronal DNase II exhibited therapeutic benefits.

CONCLUSIONS

DNase II deficiency and cytoplasmic dsDNA accumulation can initiate tau phosphorylation, suggesting DNase II as a potential therapeutic target for tau-associated disorders.

摘要

背景

脱氧核糖核酸酶 2（DNase II）在清除细胞质中的双链 DNA（dsDNA）方面发挥着关键作用。DNase II 的缺乏会导致细胞质中 DNA 的积累。神经元中的持续 dsDNA 是衰老和神经退行性疾病（包括阿尔茨海默病（AD））的早期病理标志之一。然而，目前尚不清楚 DNase II 和神经元细胞质中的 dsDNA 如何影响神经发病机制。tau 过度磷酸化是 AD 发病机制的关键因素。DNase II 和神经元细胞质中的 dsDNA 对神经元 tau 过度磷酸化的影响仍不清楚。

方法

通过免疫组织化学和免疫标记法测量 WT 和不同年龄的 Tau-P301S 小鼠的神经元 DNase II 和 dsDNA 水平，并通过 ELISA 测量 AD 患者的血浆中 DNase II 的水平。为了研究 DNase II 对 tau 病变的影响，通过免疫标记法、免疫印迹法或 ELISA 评估神经元 DNase II 缺陷型 WT 小鼠、神经元 DNase II 缺陷型 Tau-P301S 小鼠和神经元 DNase II 过表达型 Tau-P301S 小鼠大脑中的磷酸化 tau、磷酸激酶、磷酸酶、突触蛋白、神经胶质增生和促炎细胞因子的水平。使用 Morris 水迷宫测试、Y 迷宫测试、新物体识别测试和旷场测试来确定认知表现。

结果

AD 患者的大脑和血浆中 DNase II 的水平明显降低。DNase II 也随 WT 和 Tau-P301S 小鼠神经元中年龄的增长而呈依赖性降低，同时细胞质中 dsDNA 的积累增加。神经元 DNase II 缺乏引起的 DNA 积累通过上调周期蛋白依赖性激酶 5（CDK5）和钙/钙调蛋白激活蛋白激酶 II（CaMKII）和下调磷酸酶蛋白磷酸酶 2A（PP2A）来驱动 tau 磷酸化。此外，DNase II 敲低分别诱导并显著加重 WT 和 Tau-P301S 小鼠的神经元丢失、神经炎症和认知缺陷，而神经元 DNase II 的过表达则表现出治疗益处。