Elucidating the mechanism of action of astragalus polysaccharide on ionizing radiation-induced myocardial damage based on network pharmacology and experimental research.
Due to the unavoidable impact of ionizing radiation on the heart located near the mediastinum, varying degrees of myocardial damage may occur. As a result, the clinical application of radiotherapy in cancer treatment is significantly limited. However, the molecular mechanisms underlying radiation-induced heart disease (RIHD) are not yet fully understood, and there is a lack of disease-specific treatment strategies. Astragalus polysaccharide (APS), is an active compound abundant in the traditional Chinese herb Astragalus membranaceus (Fisch.) Bunge (AS), has been shown to have cardioprotective effects against various cardiovascular diseases. Thus, this study aims to investigate the potential cardioprotective effect of APS on RIHD and its underlying molecular mechanisms. The network pharmacology results indicated that 9 core genes were identified from the biological network of the effective components of AS acting on RIHD. The results of GO enrichment analysis showed that these hub genes were mainly involved in biological processes such as cell apoptosis, cell proliferation, inflammatory response, and response to external stimuli. The results of KEGG enrichment analysis showed that these hub genes mainly regulated the occurrence of RIHD through pathways such as the EGFR signaling pathway, PI3K/Akt signaling pathway, IL-17 signaling pathway, and so on. In molecular docking analysis, we found that AKT1 and mTOR had good and stable binding abilities with the three types of glucosides rich in AS. The results of in vitro and in vivo experiments all showed that APS could not only improve cardiac dysfunction, myocardial injury, inflammatory response, and myocardial fibrosis in RIHD rats, but also alleviated apoptosis and atrophy of H9C2 cells under ionizing radiation stimulation. In addition, we also found that APS improved the accumulation of autophagic flux induced by ionizing radiation, which could be confirmed by the reversal of Beclin1, p62, LC3B proteins and accelerated degradation of accumulated autophagic vesicles. Rapamycin (Rap) was a classic autophagy flux inducer that could attenuate the improvement effect of APS on H9C2 cell apoptosis under ionizing radiation stimulation. Finally, we found that APS could reverse the inhibition of PI3K/Akt/mTOR signaling pathway activity by ionizing radiation in vitro, thereby improving ionizing radiation-induced autophagy flux accumulation, cardiomyocyte apoptosis, and atrophy. All in all, this study provides important evidence for understanding the molecular mechanisms of the cross-talk between autophagy and apoptosis, and provides new directions and insights for APS combined with autophagy regulators as a therapeutic strategy for RIHD.
Jiang B
，Wang Y
，Zhi X
，Liu A
，Wang L
，Wang X
，Wang Z
，Duan Y
，Li Y
，Zhang Z
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Piezo1 Modulates Neuronal Autophagy and Apoptosis in Cerebral Ischemia-Reperfusion Injury Through the AMPK-mTOR Signaling Pathway.
Cerebral ischemia-reperfusion (I/R) injury is a complex pathophysiological process involving multiple mechanisms, including apoptosis and autophagy, which can lead to significant neuronal damage. PIEZO1, a stretch-activated ion channel, has recently emerged as a potential regulator of cellular responses to ischemic conditions. However, its role in neuronal cell survival and death during ischemic events is not well elucidated. This study aimed to ascertain the regulatory function of PIEZO1 in neuronal cell apoptosis and autophagy in an in vitro model of hypoxia-reoxygenation and an in vivo model of brain I/R injury. HT22 hippocampal neuronal cells were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate ischemic conditions, with subsequent reoxygenation. In vitro, PIEZO1 expression was silenced using small interfering RNA (si-RNA) transfection. The effects on cell viability, apoptosis, and autophagy were assessed using CCK-8 assays, PI-Annexin/V staining combined with flow cytometry, and Western blot analysis. Additionally, intracellular Ca2+ levels in HT22 cells were measured using a Ca2+ probe. The involvement of the AMPK-mTOR pathway was investigated using rapamycin. For in vivo validation, middle cerebral artery occlusion/reperfusion (MCAO/R) in rats was employed. To determine the neuroprotective role of PIEZO1 silencing, sh-PIEZO1 adeno-associated virus was stereotaxically injected into the cerebral ventricle, and neurological and histological outcomes were assessed using neurological scoring, TTC staining, H&E staining, Nissl staining, and immunofluorescence. In HT22 cells, OGD/R injury notably upregulated PIEZO1 expression and intracellular Ca2+ levels. Silencing PIEZO1 significantly diminished OGD/R-induced Ca2+ influx, apoptosis, and autophagy, as indicated by lower levels of pro-apoptotic and autophagy-related proteins and improved cell viability. Additionally, PIEZO1 modulated the AMPK-mTOR signaling pathway, an effect that was counteracted by rapamycin treatment, implying its regulatory role. In vivo, PIEZO1 silencing ameliorated brain I/R injury in MCAO/R rats, demonstrated by improved neurological function scores and reduced neuronal apoptosis and autophagy. However, these neuroprotective effects were reversed through rapamycin treatment. Our findings indicate that PIEZO1 is upregulated following ischemic injury and facilitates Ca2+ influx, apoptosis, and autophagy via the AMPK-mTOR pathway. Silencing PIEZO1 confers neuroprotection against I/R injury both in vitro and in vivo, highlighting its potential as a therapeutic target for stroke management.
Yue Y
，Chen P
，Ren C
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Rg1 improves Alzheimer's disease by regulating mitochondrial dynamics mediated by the AMPK/Drp1 signaling pathway.
Alzheimer's disease (AD) is the most prevalent form of dementia, characterized by a complex pathogenesis that includes Aβ deposition, abnormal phosphorylation of tau protein, chronic neuroinflammation, and mitochondrial dysfunction. In traditional medicine, ginseng is revered as the 'king of herbs'. Ginseng has the effects of greatly tonifying vital energy, strengthening the spleen and benefiting the lungs, generating fluids and nourishing the blood, and calming the mind while enhancing intelligence. Ginsenoside Rg1 (Rg1) is a well-defined major active component found in ginseng, known for its relatively high content. It has been demonstrated to exhibit neuroprotective effects in both in vivo and in vitro models, capable of ameliorating Aβ and tau pathology, regulating synaptic function, and reducing inflammation, oxidative stress, and apoptosis. However, the potential of Rg1 to improve AD pathology through the regulation of mitochondrial dynamics is still uncertain.
Despite the active research efforts on drugs for AD, the currently available anti-AD medications can only slow disease progression and manage symptoms, yet unable to provide a cure for AD. Furthermore, some anti-AD drugs failed phase III and IV clinical trials due to significant side effects. Therefore, there is an urgent need to further investigate the pathogenesis of AD, to identify new therapeutic targets, and to explore more effective therapies. The aim of this study is to evaluate the potential therapeutic effects of Rg1 on APP/PS1 double transgenic mice and Aβ42-induced HT22 cell models, and to investigate the potential mechanisms through which it provides neuroprotective effects.
This study investigates the effects of Rg1 in treating AD on APP/PS1 double transgenic mice and Aβ42-induced HT22 cells. In the in vivo experiments, APP/PS1 mice were divided into a model group, Rg1-L group, Rg1-H group, and donepezil group, with C57BL/6 mice serving as the control group (n = 12 per group). The Rg1-L and Rg1-H groups were administered Rg1 at doses of 5 mg/kg/d and 10 mg/kg/d, respectively, while the donepezil group received donepezil at a dose of 1.3 mg/kg/d. Both the control and model groups received an equal volume of physiological saline daily for 28 days. Learning and spatial memory were assessed by the Morris water maze (MWM) and novel object recognition (NOR) tests, and neuronal damage by Nissl staining. Aβ deposition was analyzed through immunohistochemistry and Western blot, while the expression levels of synaptic proteins PSD95 and SYN were evaluated via immunofluorescence staining and Western blot. The dendritic spines of neurons was observed by Golgi staining.The ultrastructure of neuronal mitochondria and synapses was examined by transmission electron microscopy (TEM). Mitochondrial function was assessed through measurements of Reactive oxygen species (ROS), Superoxide Dismutase (SOD), and Adenosine Triphosphate (ATP), and Western blot analysis was performed to detect the expression levels of AMPK, p-AMPK, Drp1, p-Drp1, OPA1, Mfn1, and Mfn2, thereby investigating the protective effects of Rg1 on mitochondrial dysfunction and cognitive impairment in APP/PS1 double transgenic mice. In vitro experiments, HT22 cells were treated with Aβ42 of 10 μM for 24 h to verify the therapeutic effects of Rg1. Flow cytometry was used to detect ROS and JC-1, biochemical methods were employed to measure SOD and ATP, immunofluorescence staining was used to detect the expression levels of PSD95 and SYN, and Western blot analysis was conducted to elucidate its potential mechanisms of action.
The findings suggest that after 28 days of Rg1 treatment, cognitive dysfunction in APP/PS1 mice was improved. Pathological and immunohistochemical analyses demonstrated that Rg1 treatment significantly reduced Aβ deposition and neuronal loss. Rg1 can improve synaptic dysfunction and mitochondrial function in APP/PS1 mice. Rg1 activated AMPK, enhanced p-AMPK expression, inhibited Drp1, and reduced p-Drp1 levels, which led to increased expression of OPA1, Mfn1, and Mfn2, thereby inhibiting mitochondrial fission and facilitating mitochondrial fusion. Additionally, Rg1 effectively reversed the decrease in mitochondrial membrane potential (MMP) and the increase in ROS production induced by Aβ42 in HT22 cells, restoring SOD and ATP levels. Furthermore, Rg1 regulated mitochondrial fission mediated by the AMPK/Drp1 signaling pathway, promoting mitochondrial fusion and improving synaptic dysfunction.
Our research provides evidence for the neuroprotective mechanisms of Rg1 in AD models. Rg1 modulates mitochondrial dynamics through the AMPK/Drp1 signaling pathway, thereby reducing synaptic and mitochondrial dysfunction in APP/PS1 mice and AD cell models.
Zhang Y
，Liu S
，Cao D
，Zhao M
，Lu H
，Wang P
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