RhoGDIα is an inhibitor of RhoGDP dissociation that involves in Aβ metabolism and NFTs production in Alzheimer's disease (AD) by regulating of RhoGTP enzyme activity. Our previous research revealed that RhoGDIα, as the target of Polygala saponin (Sen), might alleviate apoptosis of the nerve cells caused by hypoxia/reoxygenation (H/R). To further clarify the role of RhoGDIα in the generation of NFTs, we explored the relationship between RhoGDIα and Tau. We found out that RhoGDIα and Tau can bind with each other and interact by using coimmunoprecipitation (Co-IP) and GST pulldown methods in vitro. This RhoGDIα-Tau partnership was further verified by using immunofluorescence colocalization and fluorescence resonance energy transfer (FRET) approaches in PC12 cells. Using the RNA interference (RNAi) technique, we found that the RhoGDIα may be involved in an upstream signaling pathway for Tau. Subsequently, in Aβ_25-35- and H/R-induced PC12 cells, forced expression of RhoGDIα via cDNA plasmid transfection was found to reduce the hyperphosphorylation of Tau, augment the expression of bcl-2 protein, and inhibit the expression of Bax protein (reducing the Bax/bcl-2 ratio) and the activity of caspase-3. In mouse AD and VaD models, forced expression of RhoGDIα via injection of a viral vector (pAAV-EGFP-RhoGDIα) into the lateral ventricle of the brain alleviated the pathological symptoms of AD and VaD. Finally, GST pulldown confirmed that the binding sites on RhoGDIα for Tau were located in the range of the ΔC33 fragment (aa 1–33). These results indicate that RhoGDIα is involved in the phosphorylation of Tau and apoptosis in AD and VaD. Overexpression of RhoGDIα can inhibit the generation of NFTs and delay the progress of these two types of dementia.

Graphical abstract

中文翻译：

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RhoGDIα/Tau 之间的直接相互作用可减轻阿尔茨海默病和血管性痴呆中 Tau 的过度磷酸化

RhoGDIα 是一种 RhoGDP 解离抑制剂，通过调节 RhoGTP 酶活性参与阿尔茨海默病 (AD) 中的 Aβ 代谢和 NFT 产生。我们前期的研究表明，RhoGDIα作为远志皂苷（Sen）的靶标，可能会减轻缺氧/复氧（H/R）引起的神经细胞凋亡。为了进一步阐明 RhoGDIα 在 NFT 生成中的作用，我们探讨了 RhoGDIα 和 Tau 之间的关系。我们通过体外共免疫沉淀 (Co-IP) 和 GST Pulldown 方法发现 RhoGDIα 和 Tau 可以相互结合并相互作用。通过在 PC12 细胞中使用免疫荧光共定位和荧光共振能量转移 (FRET) 方法，进一步验证了 RhoGDIα-Tau 伙伴关系。利用RNA干扰（RNAi）技术，我们发现RhoGDIα可能参与Tau的上游信号通路。随后，在 Aβ _25-35和 H/R 诱导的 PC12 细胞中，发现通过 cDNA 质粒转染强制表达 RhoGDIα 可减少 Tau 的过度磷酸化，增加 bcl-2 蛋白的表达，并抑制 Bax 蛋白的表达（降低 Bax/bcl-2 比率）和 caspase-3 的活性。在小鼠 AD 和 VaD 模型中，通过将病毒载体 ( pAAV-EGFP-RhoGDIα ) 注射到大脑侧脑室强制表达 RhoGDIα 可减轻 AD 和 VaD 的病理症状。最后，GST Pulldown 证实 RhoGDIα 上 Tau 的结合位点位于 ΔC33 片段 (aa 1-33) 的范围内。这些结果表明，RhoGDIα 参与 AD 和 VaD 中 Tau 的磷酸化和细胞凋亡。RhoGDIα的过度表达可以抑制NFT的生成并延缓这两类痴呆的进展。

图形概要