Neuroprotection Effect of Astragaloside IV from 2-DG-Induced Endoplasmic Reticulum Stress

Abstract

Objective. Astragaloside IV shows neuroprotective activity, but its mechanism remains unclear. To investigate whether astragaloside IV protects from endoplasmic reticulum stress (ERS), we focus on the regulation of glycogen synthase kinase-3β (GSK-3β) and mitochondrial permeability transition pore (mPTP) by astragaloside IV in neuronal cell PC12. Methods and Results. PC12 cells treated with different concentrations of ERS inductor 2-deoxyglucose (2-DG) (25-500 μM) showed a significant increase of glucose-regulated protein 78 (GRP 78) and GRP 94 expressions and a decrease of tetramethylrhodamine ethyl ester (TMRE) fluorescence intensity and mitochondrial membrane potential (∆Ψm), with the peak effect seen at 50 μM, indicating that 2-DG induces ERS and the mPTP opening. Similarly, 50 μM of astragaloside IV increased the GSK-3β phosphorylation at Ser9 most significantly. Next, we examined the neuroprotection of astragaloside IV by dividing the PC12 cells into control group, 2-DG treatment group, astragaloside IV plus 2-DG treatment group, and astragaloside IV only group. PC12 cells treated with 50 μM 2-DG for different time courses (0-36 hr) showed a significant increase of Cleaved-Caspase-3 with the peak at 6 hr. 2-DG significantly induced cell apoptosis and increased the green fluorescence intensity of Annexin V-FITC, and these effects were reversed by astragaloside IV. Such a result indicates that astragaloside IV protected neural cell survival from ERS. 2-DG treatment significantly increased the expressions of inositol-requiring ER-to-nucleus signal kinase 1 (IRE1), phosphor-protein kinase R-like ER kinase (p-PERK), but not affect the transcription factor 6 (ATF6) expression. 2-DG treatment significantly decreased the phosphorylation of GSK-3β and significantly reduced the TMRE fluorescence intensity and ∆Ψm, following mPTP open. Astragaloside IV significantly inhibited the above effects caused by 2-DG, except the upregulation of ATF6 protein. Taken together, astragaloside IV significantly inhibited the ERS caused by 2-DG. Conclusion. Our data suggested that astragaloside IV protects PC12 cells from ERS by inactivation of GSK-3β and preventing the mPTP opening. The GRP 78, GRP 94, IRE1, and PERK signaling pathways but not ATF6 are responsible for GSK-3β inactivation and neuroprotection by astragaloside IV.

Involvement of endoplasmic reticulum stress in trigeminal ganglion corneal neuron injury in dry eye disease

“…Four ERS-and apoptosis-related genes with increased expression-namely, the GRP78, GRP94, XBP1, and CHOP genes-were further verified by qPCR. GRP78, GRP94 and XBP1 are highly relevant to neuronal ERS (Fu et al, 2020;Zhou et al, 2022), which is also upstream of CHOP mRNA expression in cell apoptosis (Pan et al, 2021). Therefore, ERS plays a vital role in TG corneal neuron injury in eDED.…”

SERP1 reduces inchoate acute hepatic injury through regulation of endoplasmic reticulum stress via the GSK3β/β‑catenin/TCF/LEF signaling pathway

“…In the research of cancer and neuropsychiatric diseases, GSK3β has been selected as a therapeutic target and has attracted increasing attention. Astragaloside IV protects nerve cells from ERS by inactivating GSK3β (41). Additionally, GSK3β regulated by ERS participates in the pathogenesis of Alzheimer's disease (42).…”

Roles and Mechanisms of Astragaloside IV in Combating Neuronal Aging

“…This process is important to the maintenance of cellular homeostasis [ 62 ]. To combat the ER stress, astragaloside IV attenuates the expression of phosphor-protein kinase R-like ER kinase (p-PERK) and inositol-requiring ER-to-nucleus signal kinase 1 (IRE1), while promoting the phosphorylation of GSK-3 β to protect the neurons [ 63 ]. Protein kinase A (PKA) triggers the activation of the cyclic AMP response element-binding protein (CREB) to shield the mitochondria from damage.…”