Knockdown of microRNA-17-5p Enhances the Neuroprotective Effect of Act A/Smads Signal Loop After Ischemic Injury

Neuroprotective Effects of Activin A against Cerebral Ischemia/Reperfusion Injury in Mice by Enhancing Nrf2 Expression to Attenuate Neuronal Ferroptosis

Activin A (Act A) is a member of the transforming growth factor-β (TGF-β) superfamily and can protect against ischemic cerebral injury. Ferroptosis, a newly discovered type of programmed cell death, contributes to the pathogenesis of cerebral ischemia-reperfusion injury (CIRI). However, little is known on whether Act A can modulate neuronal ferroptosis to protect against CIRI in a mouse model of middle cerebral artery occlusion (MCAO) and an HT22 cell model of oxygen-glucose deprivation/reoxygenation (OGD/R). The results indicated that Act A treatment relieved CIRI by improving neurological deficits and reducing the infarct volume in mice. MCAO stimulated iron accumulation and malondialdehyde formation and upregulated ACSL4 expression but downregulated GPX4 expression, a hallmark of ferroptosis in the brain of mice. Treatment with Act A significantly mitigated MCAO-triggered ferroptosis in the brain of mice. Furthermore, Act A treatment enhanced the MCAO-upregulated nuclear factor erythroid-2-related factor 2 (Nrf2) expression in the brains of mice. Similar results were observed in HT22 cells following OGD/R and pretreatment with Act A. The neuronal protective effect of Act A in HT22 cells was attenuated by treatment with ML385, an Nrf2 inhibitor. To conclude, Act A attenuated CIRI by enhancing Nrf2 expression and inhibiting neuronal ferroptosis.

Dexmedetomidine attenuates oxygen-glucose deprivation/ reperfusion-induced inflammation through the miR-17-5p/ TLR4/ NF-κB axis

Background

Dexmedetomidine (DEX) is a selective agonist of α2-adrenergic receptors with anesthetic activity and neuroprotective benefits. However, its mechanism of action at the molecular level remains poorly defined. In this study, we investigated the protective effects of DEX on oxygen-glucose deprivation/ reperfusion (OGD/R)-induced neuronal apoptosis in PC12 cells, and evaluated its underlying mechanism(s) of neuroprotection and anti-inflammation.

Methods

An OGD/R model in PC12 cells was established. PC12 cells were cultured and divided into control, OGD/R, and OGD/R + DEX (1 μM, 10 μM, 50 μM) groups. Cell apoptosis was analyzed by flow cytometry and expression profiles were determined by qRT-PCR, western blot analysis, and enzyme linked immunosorbent assays (ELISA). The interaction between miRNA and its downstream targets was evaluated through luciferase reporter assays.

Results

DEX significantly decreased apoptosis rates and inhibited interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6) release (P < 0.05). While expression of the pro-apoptotic proteins Bax and Caspase-3 was down-regulated, expression of Bcl-2 was upregulated in a dose-dependent manner (P < 0.05). Interestingly, miR-17-5p expression was down-regulated in the OGD/R group (compared to controls). Toll-like receptor 4 (TLR4), a key regulator of nuclear factor kappa-B (NF-κB) signaling, was identified as a novel target of miR-17-5p in PC12 cells. miR-17-5p expression was upregulated in the OGD/R + DEX group, suppressing TLR4 expression and reducing the secretion of proinflammatory cytokines.

Conclusion

DEX inhibits OGD/R-induced inflammation and apoptosis in PC12 cells by increasing miR-17-5p expression, downregulating TLR4, and inhibiting NF-κB signaling.

Direct moxibustion exerts an analgesic effect on cervical spondylotic radiculopathy by increasing autophagy via the Act A/Smads signaling pathway

BACKGROUND

Direct moxibustion (DM) is reported to be useful for cervical spondylotic radiculopathy (CSR), but the analgesic mechanism remains unknown. Autophagy plays a protective role in neuronal apoptosis, Act A/Smads signaling pathway has been confirmed to be associated with the activation of autophagy. The study aimed to explore the effect of DM on autophagy in rats with CSR and the involvement of Act A/Smads signaling pathway.

METHODS

Rats were randomly divided into Sham, CSR, CSR + DM, CSR + DM + 3-MA (PI3K inhibitor), and CSR + DM + SB (Act A inhibitor) group. Three days after establishment of CSR model with a fish line inserted under the axilla of the nerve roots, DM at Dazhui (GV14) was performed six times once for seven consecutive days. Western blot and immunofluorescence staining were used to observe the expression of the neuronal autophagy molecule LC3II/I, Atg7, and Act A/Smads signaling molecule Act A, p-Smad2, and p-Smad3. Bcl-2/Bax mRNA expression was measured by real time PCR.

RESULTS

DM improved the pain threshold and motor function of CSR rats and promoted the expression of Act A, p-Smad2, p-Smad3, LC3II/I, and Atg7 in the entrapped-nerve root spinal dorsal horn. DM reduced the expression of Bax mRNA and decreased the number of apoptotic neurons. 3-MA and Act A inhibitor SB suppressed the expression of above-mentioned proteins and reduced the protective effect of DM on apoptotic neurons.

CONCLUSION

DM exerts analgesic effects by regulating the autophagy to reduce cell apoptosis and repair nerve injury, and this feature may be related to the Act A/Smads signaling pathway.

Exploration of the mechanism of luteolin against ischemic stroke based on network pharmacology, molecular docking and experimental verification

Stroke is a leading cause of morbidity and mortality worldwide. As the most common type of stroke cases, treatment effectiveness is still limited despite intensive research. Recently, traditional Chinese medicine has attracted attention because of potential benefits for stroke treatment. Among these, luteolin, a natural plant flavonoid compound, offers neuroprotection following against ischemic stroke, although the specific mechanisms are unknown. Here we used network pharmacology, molecular docking, and experimental verification to explore the mechanisms whereby luteolin can benefit stroke recovery. The pharmacological and molecular properties of luteolin were obtained from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. The potential targets of luteolin and ischemic stroke were collected from interrogating public databases. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed by Funrich and Database for Annotation, Visualization and Integrated Discovery respectively, a luteolin-target-pathway network constructed using Cytoscape, Autodock vina was used for molecular docking simulation with Discovery Studio was used to visualize and analyze the docked conformations. Lastly, we employed an in vitro model of stroke injury to evaluate the effects of luteolin on cell survival and expression of the putative targets. From 95 candidate luteolin target genes, our analysis identified six core targets . KEGG analysis of the candidate targets identified that luteolin provides therapeutic effects on stroke through TNF signaling and other pathways. Our experimental analyses confirmed the conclusions analyzed above. In summary, the molecular and pharmacological mechanisms of luteolin against stroke are indicated in our study from a systematic perspective.

MiR-17-5p-mediated endoplasmic reticulum stress promotes acute myocardial ischemia injury through targeting Tsg101

Cardiovascular diseases are the leading cause of death globally, among which acute myocardial infarction (AMI) frequently occurs in the heart and proceeds from myocardium ischemia and endoplasmic reticulum (ER) stress-induced cell death. Numerous studies on miRNAs indicated their potential as diagnostic biomarkers and treatment targets for heart diseases. Our study investigated the role of miR-17-5p and its regulatory mechanisms during AMI. Echocardiography, MTT, flow cytometry assay, evaluation of caspase-3 and lactate dehydrogenase (LDH) activity were conducted to assess cell viability, apoptosis in an MI/R mice model, and an H2O2-induced H9c2 hypoxia cell model, respectively. The expression levels of ER stress response-related biomarkers were detected using qRT-PCR, IHC, and western blotting assays. The binding site of miR-17-5p on Tsg101 mRNA was determined by bioinformatic prediction and luciferase reporter assay. The expression levels of miR-17-5p were notably elevated in MI/R mice and hypoxia cell models, accompanied by enhanced cell apoptosis. Inhibition of miR-17-5p led to decreased apoptosis related to ER stress response in the hypoxia model, which could be counteracted by knockdown of Tsg101 (tumor susceptibility gene 101). Transfection with miR-17-5p mimics downregulated the expression of Tsg101 in H9c2 cells. Luciferase assay demonstrated the binding between miR-17-5p and Tsg101. Moreover, 4-PBA, the inhibitor of the ER stress response, abolished shTsg101 elevated apoptosis in hypoxic H9c2 cells. Our findings investigated the pro-apoptotic role of miR-17-5p during MI/R, disclosed the specific mechanism of miR-17-5p/Tsg101 regulatory axis in ER stress-induced myocardium injury and cardiomyocytes apoptosis, and presented a promising diagnostic biomarker and potential target for therapy of AMI.

GAS5 knockdown ameliorates apoptosis and inflammatory response by modulating miR-26b-5p/Smad1 axis in cerebral ischaemia/reperfusion injury

Ischemic stroke (IS) caused by cerebral arterial embolism remains the leading cause of disability and death worldwide. Cerebral ischemia / reperfusion (CI / R) injury is one of the common complications of ischemic stroke. Growth arrest specific transcript 5 (GAS5) has been found to be abnormally expressed in various tumors. However, the role and potential molecular mechanisms of GAS5 in CI / R-induced injury remain unknown. This study established a CI / R injury model in vivo and in vitro. The results showed that the expression of GAS5 was increased in CI / R rats, while miR-26b-5p expression was decreased. Besides, knockdown of GAS5 by siRNA (si-GAS5) reversed CI / R-induced apoptosis and inflammatory responses. Notably, bioinformatics analysis indicated that GAS5 competitively adsorbed miR-26b-5p, and the relationship was further confirmed by pull-down assay. In addition, miR-26b-5p overexpression reversed CI / R-induced apoptosis and inflammatory responses, whereas low expression of miR-26b-5p had the opposite effect. Moreover, TargetScan assay predicted that drosophila mothers against decapentaplegic protein 1 (Smad1) was a target of miR-26b-5p, and miR-26b-5p overexpression inhibited Smad1 expression. Conversely, Smad1 overexpression reversed the inhibitory effect of miR-26b-5p on CI / R-induced apoptosis and inflammatory responses in rats. Collectively, these results indicate that GAS5 knockdown can improve apoptosis and inflammatory responses by modulating the miR-26b-5p / Smad1 axis in CI / R rats.