MicroRNA-494 improves functional recovery and inhibits apoptosis by modulating PTEN/AKT/mTOR pathway in rats after spinal cord injury

PTEN inhibition promotes robust growth of bulbospinal respiratory axons and partial recovery of diaphragm function in a chronic model of cervical contusion spinal cord injury

High spinal cord injury (SCI) leads to persistent and debilitating compromise in respiratory function. Cervical SCI not only causes the death of phrenic motor neurons (PhMNs) that innervate the diaphragm, but also damages descending respiratory pathways originating in the rostral ventral respiratory group (rVRG) located in the brainstem, resulting in denervation and consequent silencing of spared PhMNs located caudal to injury. It is imperative to determine whether interventions targeting rVRG axon growth and respiratory neural circuit reconnection are efficacious in chronic cervical contusion SCI, given that the vast majority of individuals are chronically-injured and most cases of SCI involve contusion-type damage to the cervical region. We therefore employed a rat model of chronic cervical hemicontusion to test therapeutic manipulations aimed at reconstructing damaged rVRG-PhMN-diaphragm circuitry to achieve recovery of respiratory function. At a chronic time point post-injury, we systemically administered: an antagonist peptide directed against phosphatase and tensin homolog (PTEN), a central inhibitor of neuron-intrinsic axon growth potential; an antagonist peptide directed against receptor-type protein tyrosine phosphatase sigma (PTPσ), another important negative regulator of axon growth capacity; or a combination of these two peptides. PTEN antagonist peptide (PAP4) promoted partial recovery of diaphragm motor activity out to nine months post-injury (though this effect depended on the anesthetic regimen used during recording), while PTPσ peptide did not impact diaphragm function after cervical SCI. Furthermore, PAP4 promoted robust growth of descending bulbospinal rVRG axons caudal to the injury within the denervated portion of the PhMN pool, while PTPσ peptide did not affect rVRG axon growth at this location that is critical to control of diaphragmatic respiratory function. In conclusion, we find that, when PTEN inhibition is targeted at a chronic time point following cervical contusion, our non-invasive PAP4 strategy can successfully promote significant regrowth of damaged respiratory neural circuitry and also partial recovery of diaphragm motor function.

Recent advances on signaling pathways and their inhibitors in spinal cord injury

Spinal cord injury (SCI) is a serious and disabling central nervous system injury. Its complex pathological mechanism can lead to sensory and motor dysfunction. It has been reported that signaling pathway plays a key role in the pathological process and neuronal recovery mechanism of SCI. Such as PI3K/Akt, MAPK, NF-κB, and Wnt/β-catenin signaling pathways. According to reports, various stimuli and cytokines activate these signaling pathways related to SCI pathology, thereby participating in the regulation of pathological processes such as inflammation response, cell apoptosis, oxidative stress, and glial scar formation after injury. Activation or inhibition of relevant pathways can delay inflammatory response, reduce neuronal apoptosis, prevent glial scar formation, improve the microenvironment after SCI, and promote neural function recovery. Based on the role of signaling pathways in SCI, they may be potential targets for the treatment of SCI. Therefore, understanding the signaling pathway and its inhibitors may be beneficial to the development of SCI therapeutic targets and new drugs. This paper mainly summarizes the pathophysiological process of SCI, the signaling pathways involved in SCI pathogenesis, and the potential role of specific inhibitors/activators in its treatment. In addition, this review also discusses the deficiencies and defects of signaling pathways in SCI research. It is hoped that this study can provide reference for future research on signaling pathways in the pathogenesis of SCI and provide theoretical basis for SCI biotherapy.

Targeted Therapy of Spinal Cord Injury: Inhibition of Apoptosis Is a Promising Therapeutic Strategy

Spinal cord injury (SCI) is a serious disabling central nervous system injury that can lead to motor, sensory, and autonomic dysfunction below the injury level. SCI can be divided into primary injury and secondary injury according to pathological process. Primary injury is mostly irreversible, while secondary injury is a dynamic regulatory process. Apoptosis is an important pathological event of secondary injury and has a significant effect on the recovery of nerve function after SCI. Nerve cell death can further aggravate the microenvironment of the injured site, leading to neurological dysfunction and thus affect the clinical outcome of patients. Therefore, apoptosis plays a crucial role in the pathological progression of secondary SCI, while inhibiting apoptosis may be a promising therapeutic strategy for SCI. This review will summarize and explore the factors that lead to cell death after SCI, the influence of cross talk between signaling pathways and pathways involved in apoptosis and discuss the influence of apoptosis on SCI, and the therapeutic significance of targeting apoptosis on SCI. This review helps us to understand the role of apoptosis in secondary SCI and provides a theoretical basis for the treatment of SCI based on apoptosis.

Mesenchymal stem cell-derived exosomes as a new drug carrier for the treatment of spinal cord injury: A review

Spinal cord injury (SCI) is a devastating traumatic disease seriously impairing the quality of life in patients. Expectations to allow the hopeless central nervous system to repair itself after injury are unfeasible. Developing new approaches to regenerate the central nervous system is still the priority. Exosomes derived from mesenchymal stem cells (MSC-Exo) have been proven to robustly quench the inflammatory response or oxidative stress and curb neuronal apoptosis and autophagy following SCI, which are the key processes to rescue damaged spinal cord neurons and restore their functions. Nonetheless, MSC-Exo in SCI received scant attention. In this review, we reviewed our previous work and other studies to summarize the roles of MSC-Exo in SCI and its underlying mechanisms. Furthermore, we also focus on the application of exosomes as drug carrier in SCI. In particular, it combs the advantages of exosomes as a drug carrier for SCI, imaging advantages, drug types, loading methods, etc., which provides the latest progress for exosomes in the treatment of SCI, especially drug carrier.

Renoprotective Effect of Pitavastatin against TAA-Induced Renal Injury: Involvement of the miR-93/PTEN/AKT/mTOR Pathway

This research investigated if pitavastatin (Pita) might protect rats' kidneys against thioacetamide (TAA). By altering the PTEN/AKT/mTOR pathway, pitavastatin may boost kidney antioxidant capacity and minimize oxidative damage. Statins have several benefits, including antioxidant and anti-inflammatory characteristics. The principal hypothesis of this study was that Pita can regulate the miR-93/PTEN/AKT/mTOR pathways, which is thought to be responsible for its renoprotective effects. The experiment divided male rats into four groups. Group 1 included untreated rats as the control. Group 2 included rats which received TAA (100 mg/kg intraperitoneally thrice a week for two weeks) to destroy their kidneys. Groups 3 and 4 included rats which received Pita orally at 0.4 and 0.8 mg/kg for 14 days after TAA injections. Renal injury increased BUN, creatinine, and MDA levels and decreased glutathione (GSH) levels. Pitavastatin prevented these alterations. TAA decreased PTEN and increased miR-93, Akt, p-Akt, mTOR, and Stat3 in the kidneys. Pitavastatin also regulated the associated culprit pathway, miR-93/PTEN/Akt/mTOR. In addition, TAA induced adverse effects on the kidney tissue, which were significantly ameliorated by pitavastatin treatment. The findings suggest that pitavastatin can attenuate renal injury, likely by regulating the miR-93/PTEN/Akt/mTOR pathway. This modulation of the pathway appears to contribute to the protective effects of pitavastatin against TAA-induced renal injury, adding to the growing evidence of the pleiotropic benefits of statins in renal health.

PTEN inhibition promotes robust growth of bulbospinal respiratory axons and partial recovery of diaphragm function in a chronic model of cervical contusion spinal cord injury

High spinal cord injury (SCI) leads to persistent and debilitating compromise in respiratory function. Cervical SCI not only causes the death of phrenic motor neurons (PhMNs) that innervate the diaphragm, but also damages descending respiratory pathways originating in the rostral ventral respiratory group (rVRG) located in the brainstem, resulting in denervation and consequent silencing of spared PhMNs located caudal to injury. It is imperative to determine whether interventions targeting rVRG axon growth and respiratory neural circuit reconnection are efficacious in chronic cervical contusion SCI, given that the vast majority of individuals are chronically-injured and most cases of SCI involve contusion-type damage to the cervical region. We therefore employed a clinically-relevant rat model of chronic cervical hemicontusion to test therapeutic manipulations aimed at reconstructing damaged rVRG-PhMN-diaphragm circuitry to achieve recovery of respiratory function. At a chronic time point post-injury, we systemically administered: an antagonist peptide directed against phosphatase and tensin homolog (PTEN), a central inhibitor of neuron-intrinsic axon growth potential; an antagonist peptide directed against receptor-type protein tyrosine phosphatase sigma (PTPσ), another important negative regulator of axon growth capacity; or a combination of these two peptides. PTEN antagonist peptide (PAP4) promoted partial recovery of diaphragm motor activity out to nine months post-injury, while PTPσ peptide did not impact diaphragm function after cervical SCI. Furthermore, PAP4 promoted robust growth of descending bulbospinal rVRG axons caudal to the injury within the denervated portion of the PhMN pool, while PTPσ peptide did not affect rVRG axon growth at this location that is critical to control of diaphragmatic respiratory function. In conclusion, we find that, when PTEN inhibition is targeted at a chronic time point following cervical contusion that is most relevant to the SCI clinical population, our non-invasive PAP4 strategy can successfully promote significant regrowth of damaged respiratory neural circuitry and also partial recovery of diaphragm motor function.

HIGHLIGHTS

PTEN antagonist peptide promotes partial diaphragm function recovery in chronic cervical contusion SCI.PTPσ inhibitory peptide does not impact diaphragm function recovery in chronic cervical contusion SCI.PTEN antagonist peptide promotes growth of bulbospinal rVRG axons in chronic cervical contusion SCI.PTPσ peptide does not affect rVRG axon growth in chronic cervical contusion SCI.

Tenuigenin activates the IRS1/Akt/mTOR signaling by blocking PTPN1 to inhibit autophagy and improve locomotor recovery in spinal cord injury

ETHNOPHARMACOLOGICAL RELEVANCE

Tenuigenin (TEN) is a main pharmacologically active component of Polygala tenuifolia Willd. (Polygalaceae), which has shown neuroprotective functions in Alzheimer's disease. Moreover, TEN also demonstrated an anti-oxidative impact in an in vitro model of Parkinson's disease, reducing damage and loss of dopaminergic neurons.

AIM

This work focuses on the impact of TEN on locomotor recovery following spinal cord injury (SCI) and underpinning molecules involved.

METHODS

A rat model of SCI was generated, and the rats were treated with TEN, oe-PTPN1 (PTP non-receptor type 1), a protein kinase B (Akt)/mammalian target of rapamycin (mTOR) antagonist LY294002, or an autophagy inhibitor 3-methyladenine (3-MA). Subsequently, locomotor function was detected. Pathological changes and neuronal activity in the spinal cord tissues were analyzed by hematoxylin and eosin staining, Nissl staining, and TUNEL assays. Protein expression of Beclin-1 and microtubule associated protein 1 light chain 3 beta (LC3B)-II/LC3B-I, PTPN1, IRS1, mTOR, and phosphorylated Akt (p-Akt) was analyzed by western blot assays. The LC3B expression was further examined by immunofluorescence staining.

RESULTS

Treatment with TEN restored the locomotor function of SCI rats, reduced the cavity area and cell apoptosis, upregulated growth-associated protein 43 and neurofilament 200, and decreased the Beclin-1 and LC3B-II/LC3B-I levels in the spinal cord. TEN suppressed PTPN1 protein level, while PTPN1 suppressed IRS1 protein to reduce the p-Akt and mTOR levels. Either PTPN1 overexpression or LY294002 treatment blocked the promoting effect of TEN on SCI recovery. However, treatment with 3-MA suppressed autophagy, which consequently rescued the locomotor function and reduced neuron loss induced by PTPN1.

CONCLUSION

This study demonstrates that TEN suppresses autophagy to promote function recovery in SCI rats by blocking PTPN1 and rescuing the IRS1/Akt/mTOR signaling.

Recent advance in bioactive hydrogels for repairing spinal cord injury: material design, biofunctional regulation, and applications

Functional hydrogels show potential application in repairing spinal cord injury (SCI) due to their unique chemical, physical, and biological properties and functions. In this comprehensive review, we present recent advance in the material design, functional regulation, and SCI repair applications of bioactive hydrogels. Different from previously released reviews on hydrogels and three-dimensional scaffolds for the SCI repair, this work focuses on the strategies for material design and biologically functional regulation of hydrogels, specifically aiming to show how these significant efforts can promoting the repairing performance of SCI. We demonstrate various methods and techniques for the fabrication of bioactive hydrogels with the biological components such as DNA, proteins, peptides, biomass polysaccharides, and biopolymers to obtain unique biological properties of hydrogels, including the cell biocompatibility, self-healing, anti-bacterial activity, injectability, bio-adhesion, bio-degradation, and other multi-functions for repairing SCI. The functional regulation of bioactive hydrogels with drugs/growth factors, polymers, nanoparticles, one-dimensional materials, and two-dimensional materials for highly effective treating SCI are introduced and discussed in detail. This work shows new viewpoints and ideas on the design and synthesis of bioactive hydrogels with the state-of-the-art knowledges of materials science and nanotechnology, and will bridge the connection of materials science and biomedicine, and further inspire clinical potential of bioactive hydrogels in biomedical fields.

MicroRNA-494 regulates high glucose-induced cardiomyocyte apoptosis and autophagy by PI3K/AKT/mTOR signalling pathway

AIMS

Diabetic cardiomyopathy (DCM) is one of the major cardiovascular complications of diabetes. However, the mechanism of DCM is not fully understood. Studies have confirmed that certain microRNAs (miRNAs/miRs) are key regulators of DCM. The aim of this study was to investigate the role and mechanism of microRNA (miR)-494 in cardiomyocyte apoptosis and autophagy induced by high glucose (HG).

METHODS AND RESULTS

By establishing a rat DCM model and an HG-treated H9c2 cells injury model, cardiac function was detected by echocardiography, myocardial tissue was stained by immunohistochemistry, and Cell Counting Kit-8 assay and lactate dehydrogenase assay were used to detect the cardiomyocyte injury. Cell apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labelling staining, and western blotting was used to detect death and autophagy. The results showed that the expression level of miR-494 was higher in the myocardial tissue of DCM rats and the myocardial cells of H9c2 treated with HG. Compared with the corresponding negative control groups, miR-494 mimics enhanced HG-induced apoptosis and autophagy, whereas miR-494 inhibitors showed the opposite effect, corresponding PI3K, AKT, and mTOR phosphorylation level has changed.

CONCLUSIONS

These findings identify that miR-494 could regulate cell apoptosis and autophagy through PI3K/AKT/mTOR signalling pathway, participating in the regulation of cardiomyocyte cell damage after HG. These findings provide new insights for the further study of the molecular mechanism and treatment of DCM.

MicroRNAs in spinal cord injury: A narrative review

Spinal cord injury (SCI) is a global medical problem with high disability and mortality rates. At present, the diagnosis and treatment of SCI are still lacking. Spinal cord injury has a complex etiology, lack of diagnostic methods, poor treatment effect and other problems, which lead to the difficulty of spinal cord regeneration and repair, and poor functional recovery. Recent studies have shown that gene expression plays an important role in the regulation of SCI repair. MicroRNAs (miRNAs) are non-coding RNA molecules that target mRNA expression in order to silence, translate, or interfere with protein synthesis. Secondary damage, such as oxidative stress, apoptosis, autophagy, and inflammation, occurs after SCI, and differentially expressed miRNAs contribute to these events. This article reviews the pathophysiological mechanism of miRNAs in secondary injury after SCI, focusing on the mechanism of miRNAs in secondary neuroinflammation after SCI, so as to provide new ideas and basis for the clinical diagnosis and treatment of miRNAs in SCI. The mechanisms of miRNAs in neurological diseases may also make them potential biomarkers and therapeutic targets for spinal cord injuries.

Inhibition by rno-circRNA-013017 of the apoptosis of motor neurons in anterior horn and descending axonal degeneration in rats after traumatic spinal cord injury

Introduction

Spinal cord injury (SCI) often causes continuous neurological damage to clinical patients. Circular RNAs (circRNAs) are related to a lot of diseases, including SCI. We previously found five candidate circRNAs which were likely to regulate the secondary pathophysiological changes in rat model after traumatic SCI.

Methods

In this study, we first selected and overexpressed target circRNA in rats. We then explored its functional roles using various functional assays in a rat model after SCI.

Results

We found that rno-circRNA-013017-the selected target circRNA-reduced neuron apoptosis, preserved the survival and activity of motor neurons, and regulated apoptosis-related proteins at 3 days post-SCI using western blot, immunofluorescence and polymerase chain reaction. Additionally, we found that rno-circRNA-013017 inhibited descending axonal degeneration and preserved motor neurons and descending axons at 6 weeks post-SCI using immunofluorescence, biotin dextran amine diffusion tensor imaging. Finally, the overexpression of rno-circRNA-013017 promoted the locomotor function of rats after SCI using open-field test and gait analysis.

Conclusion

Focusing on the functions of rno-circRNA-013017, this study provides new options for future studies exploring therapeutic targets and molecular mechanisms for SCI.

The PI3K/AKT signalling pathway in inflammation, cell death and glial scar formation after traumatic spinal cord injury: Mechanisms and therapeutic opportunities

Objects

Traumatic spinal cord injury (TSCI) causes neurological dysfunction below the injured segment of the spinal cord, which significantly impacts the quality of life in affected patients. The phosphoinositide 3kinase/serine‐threonine kinase (PI3K/AKT) signaling pathway offers a potential therapeutic target for the inhibition of secondary TSCI. This review summarizes updates concerning the role of the PI3K/AKT pathway in TSCI.

Materials and Methods

By searching articles related to the TSCI field and the PI3K/AKT signaling pathway, we summarized the mechanisms of secondary TSCI and the PI3K/AKT signaling pathway; we also discuss current and potential future treatment methods for TSCI based on the PI3K/AKT signaling pathway.

Results

Early apoptosis and autophagy after TSCI protect the body against injury; a prolonged inflammatory response leads to the accumulation of pro‐inflammatory factors and excessive apoptosis, as well as excessive autophagy in the surrounding normal nerve cells, thus aggravating TSCI in the subacute stage of secondary injury. Initial glial scar formation in the subacute phase is a protective mechanism for TSCI, which limits the spread of damage and inflammation. However, mature scar tissue in the chronic phase hinders axon regeneration and prevents the recovery of nerve function. Activation of PI3K/AKT signaling pathway can inhibit the inflammatory response and apoptosis in the subacute phase after secondary TSCI; inhibiting this pathway in the chronic phase can reduce the formation of glial scar.

Conclusion

The PI3K/AKT signaling pathway has an important role in the recovery of spinal cord function after secondary injury. Inducing the activation of PI3K/AKT signaling pathway in the subacute phase of secondary injury and inhibiting this pathway in the chronic phase may be one of the potential strategies for the treatment of TSCI.

Quercetin Can Improve Spinal Cord Injury by Regulating the mTOR Signaling Pathway

The pathogenesis of spinal cord injury (SCI) is complex. At present, there is no effective treatment for SCI, with most current interventions focused on improving the symptoms. Inflammation, apoptosis, autophagy, and oxidative stress caused by secondary SCI may instigate serious consequences in the event of SCI. The mammalian target of rapamycin (mTOR), as a key signaling molecule, participates in the regulation of inflammation, apoptosis, and autophagy in several processes associated with SCI. Quercetin can reduce the loss of myelin sheath, enhance the ability of antioxidant stress, and promote axonal regeneration. Moreover, quercetin is also a significant player in regulating the mTOR signaling pathway that improves pathological alterations following neuronal injury. Herein, we review the therapeutic effects of quercetin in SCI through its modulation of the mTOR signaling pathway and elaborate on how it can be a potential interventional agent for SCI.

MiRNA-494-3p Regulates Bupivacaine-Induced Neurotoxicity by the CDK6-PI3K/AKT Signaling

Bupivacaine (BUP) is a long-acting amide local anesthetic that may induce strong neurotoxicity and neurological complications. In this study, we elucidate the influence of microRNA-494-3p (miR-494-3p) in BUP-induced neurotoxicity in primary mouse hippocampal neuronal cells. In this study, primary hippocampal neurons were isolated from neonatal C57BL/6 mice. The isolated neurons were treated with various doses of BUP. MTT assay was conducted to analyze neuronal viability. Gene expression measurement was done by RT-qPCR. The impact of miR-494-3p in BUP-mediated neural injury was examined using TUNEL, flow cytometry, western blotting, and ROS activity detection. The regulatory relationship between miR-494-3p and cyclin-dependent kinases 4 and 6 (CDK6) was identified using a luciferase reporter assay. BUP treatment led to neurotoxicity and miR-494-3p upregulation in primary cultured hippocampal neurons. Functionally, miR-494-3p depletion alleviated neuronal apoptosis and oxidative damage induced by BUP. We verified that miR-494-3p targeted and negatively modulated CDK6. MiR-494-3p depletion also activated PI3K/AKT signaling by elevating CDK6 expression in BUP-treated neurons. Furthermore, CDK6 knockdown or PI3K/AKT inactivation attenuated the neuroprotective role of miR-494-3p depletion. Silencing miR-494-3p exerts neuroprotective function in hippocampal neuronal cells against BUP-induced injury by the CDK6-PI3K/AKT pathway.

Rat Bone Mesenchymal Stem Cell-Derived Exosomes Loaded with miR-494 Promoting Neurofilament Regeneration and Behavioral Function Recovery after Spinal Cord Injury

Exosomes (Exo) exhibit numerous advantages (e.g., good encapsulation, high targeting efficiency, and easy to penetrate the blood-brain barrier to the central nervous system). Exosomes are recognized as prominent carriers of mRNAs, siRNAs, miRNAs, proteins, and other bioactive molecules. As confirmed by existing studies, miR-494 is important to regulate the occurrence, progression, and repair of spinal cord injury (SCI). We constructed miR-494-modified exosomes (Exo-miR-494). As indicated from related research in vitro and vivo, Exo-miR-494 is capable of effectively inhibiting the inflammatory response and neuronal apoptosis in the injured area, as well as upregulating various anti-inflammatory factors and miR-494 to protect neurons. Moreover, it can promote the regeneration of the neurofilament and improve the recovery of behavioral function of SCI rats.

MicroRNA-182 improves spinal cord injury in mice by modulating apoptosis and the inflammatory response via IKKβ/NF-κB

Spinal cord injury (SCI) is one common neurological condition which involves primary injury and secondary injury. Neuron inflammation and apoptosis after SCI is the most important pathological process of this disease. Here, we tried to explore the influence and mechanism of miRNAs on the neuron inflammatory response and apoptosis after SCI. First, by re-analysis of Gene Expression Omnibus dataset (accession GSE19890), miR-182 was selected for further study because of its suppressive effects on the inflammatory response in the various types of injuries. Functional experiments demonstrated that miR-182 overexpression promoted functional recovery, reduced histopathological changes, and alleviated spinal cord edema in mice. It was also observed that miR-182 overexpression reduced apoptosis and attenuated the inflammatory response in spinal cord tissue, as evidenced by the reduction of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β, and the induction of IL-10. Using a lipopolysaccharide (LPS)-induced SCI model in BV-2 cells, we found that miR-182 was downregulated in the BV-2 cells following LPS stimulation, and upregulation of miR-182 improved LPS-induced cell damage, as reflected by the inhibition of apoptosis and the inflammatory response. IκB kinase β (IKKβ), an upstream target of the NF-κB pathway, was directly targeted by miR-182 and miR-182 suppressed its translation. Further experiments revealed that overexpression of IKKβ reversed the anti-apoptosis and anti-inflammatory effects of miR-182 in LPS stimulated BV-2 cells. Finally, we found that miR-182 overexpression blocked the activation of the NF-κB signaling pathway in vitro and in vivo, as demonstrated by the downregulation of phosphorylated (p‑) IκB-α and nuclear p-p65. Taken together, these data indicate that miR-182 improved SCI-induced secondary injury through inhibiting apoptosis and the inflammatory response by blocking the IKKβ/NF-κB pathway. Our findings suggest that upregulation of miR-182 may be a novel therapeutic target for SCI.

Gypenoside XVII protects against spinal cord injury in mice by regulating the microRNA‑21‑mediated PTEN/AKT/mTOR pathway

Gypenoside XVII (GP‑17), one of the dominant active components of Gynostemma pentaphyllum, has been studied extensively and found to have a variety of pharmacological effects, including neuroprotective properties. However, the neuroprotective effects of GP‑17 against spinal cord injury (SCI), as well as its underlying mechanisms of action remain unknown. The present study aimed to investigate the effects of GP‑17 on motor recovery and histopathological changes following SCI and to elucidate the mechanisms underlying its neuroprotective effects in a mouse model of SCI. Motor recovery was evaluated using the Basso, Beattie and Bresnahan (BBB) locomotor rating scale. Spinal cord edema was detected by the wet/dry weight method. H&E staining was performed to examine the effect of GP‑17 on spinal cord damage. Inflammatory response production was assessed by ELISA. Candidate miRNAs were identified following the integrated analysis of the Gene Expression Omnibus (GEO) dataset GSE67515. Western blot analysis was also performed to detect the expression levels of associated proteins. The results revealed that GP‑17 treatment improved functional recovery, and suppressed neuronal apoptosis and the inflammatory response in the mouse model of SCI. Moreover, it was observed that miR‑21 expression was downregulated following SCI, whereas it was upregulated following the administration of GP‑17. The inhibition of miR‑21 eliminated the protective effects of GP‑17 on SCI‑induced neuronal apoptosis and the inflammatory response. In addition, phosphatase and tensin homologue (PTEN), a key molecule in the activation of the protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway, was identified as a target of miR‑21, and PTEN expression was downregulated by GP‑17 through miR‑21. Furthermore, the PTEN/AKT/mTOR pathway was inactivated by SCI, whereas it was re‑activated by GP‑17 through the regulation of miR‑21 in mice with SCI. On the whole, the findings of the present study suggest that GP‑17 plays a protective role in SCI via regulating the miR‑21/PTEN/AKT/mTOR pathway.

MiR-212-3p improves rat functional recovery and inhibits neurocyte apoptosis in spinal cord injury models via PTEN downregulation-mediated activation of AKT/mTOR pathway

BACKGROUND

Multiple cellular and molecular changes are involved in the etiology of spinal cord injury (SCI) and the recovery from SCI. Accumulating studies showed aberrant expression of microRNAs (miRNAs) after SCI. Here, we established in vivo and in vitro models to analyze the role of miR-212-3p in SCI.

METHODS

An in vivo model of SCI was established in Sprague-Dawley rats. SCI-induced histopathological changes of the spinal cord were observed by hematoxylin-eosin staining. Functional recovery of rats with SCI was evaluated using the Basso-Beattie-and-Bresnahan scale. PC12 cells were stimulated by lipopolysaccharide (LPS) to establish SCI model of neuronal apoptosis in vitro. Dual-luciferase reporter assay was performed to validate the potential target of miR-212-3p predicted by TargetScan 7.2. MTT assay and flow cytometry were carried out to measure the viability and apoptosis of PC12 cell, respectively. The expressions of miR-212-3p, PTEN, phosphorylated (p)-AKT, AKT, p-mTOR, mTOR, Cleaved caspase-3 and BCl-2 in spinal cord tissues and PC12 cells were analyzed by qRT-PCR or Western blot.

RESULTS

In the spinal cord of rats with SCI, the expressions of miR-212-3p, p-AKT, p-mTOR and BCl-2 were downregulated, whereas those of PTEN and Cleaved caspase-3 were upregulated. BBB scores were low, and there were histopathological changes, which were all reversed after the injection of agomiR-212-3p. MiR-212-3p directly targeted PTEN. Upregulated miR-212-3p in LPS-injured PC12 cells suppressed apoptosis, downregulated the expressions of PTEN and Cleaved caspase-3, promoted viability and upregulated the expressions of p-AKT, p-mTOR and BCl-2, which were all reversed by overexpressed PTEN.

CONCLUSION

MiR-212-3p improved functional recovery of SCI rats and inhibited LPS-induced neurocyte apoptosis by targeting PTEN to activate AKT/mTOR pathway.

Long noncoding RNA ZFAS1 aggravates spinal cord injury by binding with miR-1953 and regulating the PTEN/PI3K/AKT pathway

Multiple evidence has shown that long non-coding RNAs (lncRNAs) are novel modulators in the development of many neurological diseases, including spinal cord injury (SCI). Recently, a novel lncRNA zinc finger antisense 1 (ZFAS1) has been found to facilitate the development of many human diseases. However, the effect of ZFAS1 in SCI has not been explored. In the present study, we used the SCI mouse models and LPS-treated BV-2 cellular models to explore the role of ZFAS1 in SCI. Basso Mouse Scale score was applied to reveal locomotor function. Cresyl violet staining was used to reveal volume of spared myelin around the lesion in the injured cord. RIP and luciferase reporter assay were applied to detect binding capacity among RNAs. Next, ZFAS1 was identified to be upregulated in spinal cord tissues of SCI mice. ZFAS1 knockdown promoted functional recovery and inhibited cell apoptosis and the inflammatory response in SCI mice. ZFAS1 bound with microRNA 1953 (miR-1953), and miR-1953 was downregulated in spinal cord tissues of SCI mice. Furthermore, we confirmed that ZFAS1 promoted SCI progression via binding with miR-1953. In addition, phosphatase and tensin homolog (PTEN) was verified to be a downstream target for miR-1953 in vitro, and PTEN was upregulated in spinal cord tissues of SCI mice. Finally, we illustrated that ZFAS1 inactivated the PI3K/AKT pathway through upregulation of PTEN. In conclusion, our study revealed that ZFAS1 facilitated SCI by binding with miR-1953 and regulating the PTEN/PI3K/AKT pathway, which may provide a potential novel insight for treatment of SCI.

Respiratory axon regeneration in the chronically injured spinal cord

Promoting the combination of robust regeneration of damaged axons and synaptic reconnection of these growing axon populations with appropriate neuronal targets represents a major therapeutic goal following spinal cord injury (SCI). A key impediment to achieving this important aim includes an intrinsic inability of neurons to extend axons in adult CNS, particularly in the context of the chronically-injured spinal cord. We tested whether an inhibitory peptide directed against phosphatase and tensin homolog (PTEN: a central inhibitor of neuron-intrinsic axon growth potential) could restore inspiratory diaphragm function by reconnecting critical respiratory neural circuitry in a rat model of chronic cervical level 2 (C2) hemisection SCI. We found that systemic delivery of PTEN antagonist peptide 4 (PAP4) starting at 8 weeks after C2 hemisection promoted substantial, long-distance regeneration of injured bulbospinal rostral Ventral Respiratory Group (rVRG) axons into and through the lesion and back toward phrenic motor neurons (PhMNs) located in intact caudal C3-C5 spinal cord. Despite this robust rVRG axon regeneration, PAP4 stimulated only minimal recovery of diaphragm function. Furthermore, re-lesion through the hemisection site completely removed PAP4-induced functional improvement, demonstrating that axon regeneration through the lesion was responsible for this partial functional recovery. Interestingly, there was minimal formation of putative excitatory monosynaptic connections between regrowing rVRG axons and PhMN targets, suggesting that (1) limited rVRG-PhMN synaptic reconnectivity was responsible at least in part for the lack of a significant functional effect, (2) chronically-injured spinal cord presents an obstacle to achieving synaptogenesis between regenerating axons and post-synaptic targets, and (3) addressing this challenge is a potentially-powerful strategy to enhance therapeutic efficacy in the chronic SCI setting. In conclusion, our study demonstrates a non-invasive and transient pharmacological approach in chronic SCI to repair the critically-important neural circuitry controlling diaphragmatic respiratory function, but also sheds light on obstacles to circuit plasticity presented by the chronically-injured spinal cord.

Research progress on the regulatory role of microRNAs in spinal cord injury

Spinal cord injury (SCI) is a severe CNS injury that results in abnormalities in, or loss of, motor, sensory and autonomic nervous function. miRNAs belong to a new class of noncoding RNA that regulates the production of proteins and biological function of cells by silencing translation or interfering with the expression of target mRNAs. Following SCI, miRNAs related to oxidative stress, inflammation, autophagy, apoptosis and many other secondary injuries are differentially expressed, and these miRNAs play an important role in the progression of secondary injuries after SCI. The purpose of this review is to elucidate the differential expression and functional roles of miRNAs after SCI, thus providing references for further research on miRNAs in SCI.

MicroRNA-92a-3p enhances functional recovery and suppresses apoptosis after spinal cord injury via targeting phosphatase and tensin homolog

Spinal cord injury (SCI) is a neurological disease commonly caused by traumatic events on spinal cords. MiRNA-92a-3p is reported to be down-regulated after SCI. Our study investigated the effects of up-regulated miR-92a-3p on SCI and the underlying mechanisms. SCI mice model was established to evaluate the functional recovery of hindlimbs of mice through open-field locomotion and scored by Basso, Beattie, and Bresnahan (BBB) locomotion scale. Apoptosis of spinal cord cells was determined by flow cytometry. The effects of miR-92a-3p on SCI were detected by intrathecally injecting miR-92a-3p agomiR (agomiR-92) into the mice prior to the establishment of SCI. Phosphatase and tensin homolog (PTEN) was predicted as a target of miR-29a-3p by TargetScan. We further assessed the effects of agomiR-92 or/and overexpressed PTEN on apoptosis rates and apoptotic protein expressions in SCI mice. Moreover, the activation of protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling was determined by Western blot. The results showed that compared with the sham-operated mice, SCI mice had much lower BBB scores, and theapoptosis rate of spinal cord cells was significantly increased. After SCI, the expression of miR-92a-3p was down-regulated, and increased expression of miR-92a-3p induced by agomiR-92 further significantly increased the BBB score and decreased apoptosis. PTEN was specifically targeted by miR-92a-3p. In addition, the phosphorylation levels of Akt and mTOR were up-regulated under the treatment of agomiR-92. Our data demonstrated that the neuroprotective effects of miR-92a-3p on spinal cord safter SCI were highly associated with the activation of the PTEN/AKT/mTOR pathway.

MicroRNAs in central nervous system disorders: current advances in pathogenesis and treatment

MicroRNAs (miRNAs) are a class of short, non-coding, regulatory RNA molecules that function as post transcriptional regulators of gene expression. Altered expression of multiple miRNAs was found to be extensively involved in the pathogenesis of different neurological disorders including Alzheimer’s disease, Parkinson’s disease, stroke, epilepsy, multiple sclerosis, amyotrophic lateral sclerosis, and Huntington’s disease. miRNAs are implicated in the pathogenesis of excitotoxicity, apoptosis, oxidative stress, inflammation, neurogenesis, angiogenesis, and blood–brain barrier protection. Consequently, miRNAs can serve as biomarkers for different neurological disorders. In recent years, advances in the miRNA field led to identification of potentially novel prospects in the development of new therapies for incurable CNS disorders. MiRNA-based therapeutics include miRNA mimics and inhibitors that can decrease or increase the expression of target genes. Better understanding of the mechanisms by which miRNAs are implicated in the pathogenesis of neurological disorders may provide novel targets to researchers for innovative therapeutic strategies.

miR-495 reduces neuronal cell apoptosis and relieves acute spinal cord injury through inhibiting PRDM5

This study aims to investigate the role of miR-495 in neuronal cell apoptosis after acute spinal cord injury (ASCI). The ASCI rat model was established and the Basso, Beattie, and Bresnahan (BBB) score was assessed. miR-495, PR domain containing 5 (PRDM5), and Bcl-2 expressions were measured by qRT-PCR or western blotting. Neuronal cell line PC-12 was subjected to hypoxia condition to simulate the in vitro ASCI model. PC-12 cell apoptosis was measured by flow cytometry, and the interaction between miR-495 and PRDM5 was confirmed by dual luciferase reporter assay. Results showed that BBB score was significantly decreased in ASCI rats compared with sham rats. miR-495 expression was down-regulated in spinal cord tissue of ASCI rats and hypoxia-induced PC-12 cells, and PRDM5 protein level was up-regulated in spinal cord tissue of ASCI rats and hypoxia-induced PC-12 cells. miR-495 overexpression could reduce apoptosis of PC-12 cells, and up-regulated anti-apoptosis protein Bcl-2 protein level. Moreover, PRDM5 was a target of miR-495, and mRNA and protein levels of PRDM5 were negatively regulated by miR-495. miR-495 overexpression could reduce the hypoxia-induced PC-12 cell apoptosis, while PRDM5 overexpression abolished this inhibiting effect. The agomir-495 was injected into ASCI rats, and Bcl-2 protein level and BBB score were increased, but the PRDM5 overexpression reversed these results. Overall, we concluded that miR-495 could inhibit neuronal cell apoptosis and relieve acute spinal cord injury through inhibiting PRDM5.

MiR-132-3p Modulates MEKK3-Dependent NF-κB and p38/JNK Signaling Pathways to Alleviate Spinal Cord Ischemia-Reperfusion Injury by Hindering M1 Polarization of Macrophages

Spinal cord ischemia-reperfusion (SCIR) injury is a serious complication of open surgical and endovascular aortic procedures. MicroRNA-132-3p (miR-132-3p) has been reported to be involved in the progression of various diseases, but its role in SCIR injury is unclear. Thus, we aimed in this study to investigate the mechanism of miR-132-3p in SCIR injury and explore its pathway as a therapeutic target for SCIR injury. We first constructed a SCIR injury rat model and documented motor function in the model. Reverse transcription quantitative polymerase chain reaction (RT-qPC)R and Western blot analysis were used to detect the expression of miR-132-3p and mitogen-activated protein kinase kinase kinase 3 (MEKK3) in SCIR injury rats. The interaction between miR-132-3p and MEKK3 was identified by dual-luciferase reporter gene assay. Then, the effects of miR-132-3p and MEKK3 on macrophage M1 polarization were evaluated in vitro and in vivo by altering their expression in macrophages of SCIR injury rats, with treatments altering the nuclear factor-kappaB (NF-κB) and c-Jun N-terminal kinase (JNK)/p38 signaling pathways using SP600125, SB203580, or PDTC. The SCIR injury rats had a high Tarlov score and low miR-132-3p expression along with high MEKK3 expression. miR-132-3p could directly bind to MEKK3, and that macrophage M1 polarization and inflammation could be inhibited by overexpression of miR-132-3p through downregulating MEKK3 and inactivating the NF-κB and p38/JNK signaling pathways. Besides, increased miR-132-3p expression could decrease the injured rat Tarlov score. Overall, our study demonstrated that miR-132-3p can suppress M1 polarization of macrophages and alleviate SCIR injury by blocking the MEKK3-dependent activation of the NF-κB and p38/JNK signaling pathway. Thus, miR-132-3p and its downstream pathways may be useful targets to alleviate the symptoms of SCIR injury.

Catalpol Protects Against Spinal Cord Injury in Mice Through Regulating MicroRNA-142-Mediated HMGB1/TLR4/NF-κB Signaling Pathway

Background: Spinal cord injury (SCI) is a devastating condition that leads to paralysis, disability and even death in severe cases. Inflammation, apoptosis and oxidative stress in neurons are key pathogenic processes in SCI. Catalpol (CTP), an iridoid glycoside extracted from Rehmannia glutinosa, has many pharmacological activities, such as anti-inflammatory, anti-oxidative and anti-apoptotic properties.

Purpose: Here, we investigated whether CTP could exert neuroprotective effects against SCI, and explored the underlying mechanism involved.

Methods: SCI was induced by a weight-drop device and treated with CTP (10 mg and 60 mg/kg). Then the locomotor function of SCI mice was evaluated by the BBB scores, spinal cord edema was measured by the wet/dry weight method, oxidative stress markers and inflammatory factors were detected by commercial kits and neuronal death was measured by TUNEL staining. Moreover, the microRNA expression profile in spinal cords from mice following SCI was analyzed using miRNA microarray. In addition, reactive oxygen species (ROS) generation, inflammatory response and cell apoptosis were detected in murine microglia BV2 cells under oxygen-glucose deprivation (OGD) and CTPtreatment.

Results: Our data showed that CTP treatment could improve the functional recovery, as well as suppress the apoptosis, alleviate inflammatory and oxidative response in SCI mice. In addition, CTP was found to be up-regulated miR-142 and the protective effects of CTP on apoptosis, inflammatory and oxidative response may relate to its regulation of HMGB1/TLR4/NF-κB pathway through miR-142.

Conclusion: Our findings suggest that CTP may protect the spinal cord from SCI by suppression of apoptosis, oxidative stress and inflammatory response via miR-142/HMGB1/TLR4/NF-κB pathway.

MicroRNA-15a inhibits inflammatory response and apoptosis after spinal cord injury via targeting STAT3

OBJECTIVE

To clarify the function of microRNA-15a in the spinal cord injury (SCI) and its potential mechanism.

PATIENTS AND METHODS

The plasma levels of microRNA-15a and signal transducer and activator of transcription 3 (STAT3) in SCI patients were determined by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The correlation between the expressions of microRNA-15a and STAT3 was analyzed. The in vitro SCI model was established in H2O2-induced C8-D1A and C8B4 cells, and in vivo SCI model was established in mice by hitting T10. The mRNA and protein expressions of tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6) were detected in the SCI model. The apoptosis was examined by flow cytometry or TUNEL staining, respectively. The motor function of mouse hindlimb was evaluated using the Basso Beattie Bresnahan (BBB) standard scale. The target gene of microRNA-15a was predicted by bioinformatics and further verified by dual-luciferase reporter gene assay. The expression changes of target genes in C8-D1A and C8B4 cells with microRNA-15a overexpression or knockdown were examined by qRT-PCR and Western blot. Finally, rescue experiments were performed to evaluate the regulatory effects of microRNA-15a and STAT3 on cell apoptosis.

RESULTS

MicroRNA-15a was lowly expressed in plasma of SCI patients, while STAT3 was highly expressed with a negative correlation to microRNA-15a. Identically, microRNA-15a was lowly expressed in H2O2-induced C8-D1A and C8B4 cells, and STAT3 was highly expressed. MicroRNA-15a overexpression downregulated mRNA and protein levels of TNF-α and IL-6 in C8-D1A and C8B4 cells. BBB score was markedly low in SCI mice relative to controls. SCI mice injected with microRNA-15a mimics had higher BBB score than those injected with negative control. Besides, SCI mice with microRNA-15a overexpression had downregulated expressions of STAT3, TNF-α, and IL-6 in the impaired spinal cord tissues, as well as lower apoptotic rate. Through bioinformatics, we found binding sites between STAT3 and microRNA-15a. Their binding conditions were further verified by dual-luciferase reporter gene assay. Moreover, STAT3 expression was negatively regulated by microRNA-15a. Finally, rescue experiments showed that STAT3 overexpression could reverse the regulatory effects of microRNA-15a on expressions of TNF-α and IL-6, as well as apoptosis.

CONCLUSIONS

MicroRNA-15a expression decreases in the SCI model, which participates in the process of SCI by regulating inflammatory response and cell apoptosis via targeting STAT3.

Protocatechuic aldehyde mitigates hydrogen peroxide-triggered PC12 cell damage by down-regulating MEG3

Background: Protocatechuic aldehyde (PA) extracts from S. miltiorrhiza, which anti-oxidative and anti-inflammatory functions have been certified in diverse diseases. Nonetheless, the influence of PA in spinal cord injury (SCI) is still hazy. The research probed the function of PA in hydrogen peroxide (H₂O₂)-damaged PC12 cells.Methods: The disparate dosages of H₂O₂ (0-400 µM) or PA (0-2 µM) were applied for stimulating PC12 cells, and subsequently cell viability, apoptosis, apoptosis- and autophagy-correlative factors were evaluated. After pc-MEG3 transfection, functions of MEG3 overexpression in H₂O₂ and/or PA-managed PC12 cells were reassessed. Western blot was conducted to determine Wnt/β-catenin and PTEN/PI3K/AKT pathways.Results: H₂O₂ stimulation clearly triggered PC12 cell damage via prohibiting cell viability and accelerating apoptosis and autophagy. But, PA management mitigated H₂O₂-triggered PC12 cells damage. Down-regulated MEG3 triggered by PA was presented in H₂O₂-managed cells. What's more, overexpressed MEG3 dramatically overturned the influences of PA in H₂O₂-damaged PC12 cells. Beyond that, PA activated Wnt/β-catenin and PTEN/PI3K/AKT via repression of MEG3 in H₂O₂-managed PC12 cells.Conclusions: The results disclosed the protective impacts of PA on PC12 cells to resist H₂O₂-provoked damage. MEG3, Wnt/β-catenin and PTEN/PI3K/AKT pathways joined in adjusting the activity of PA in H₂O₂-damaged PC12 cells.

MiR-34a Inhibits Spinal Cord Injury and Blocks Spinal Cord Neuron Apoptosis by Activating Phatidylinositol 3-kinase (PI3K)/AKT Pathway Through Targeting CD47

OBJECTIVE

Dysregulation of miR-34a has been reported for its implication in neuronal development. This study aims to explore the effect and possible mechanism of miR-34a on neuron apoptosis induced by Spinal Cord Injury (SCI).

MATERIALS AND METHODS

SCI model was established using Allen's weight-drop method and rats in the sham group were performed with laminectomy without weight-drop injury. Basso Bcattie Bresnahan (BBB) rating scale was applied to evaluate the locomotor function of rats. Pathological changes of spinal cord tissues in SCI rats were observed after hematoxylin and eosin (HE) staining. Rats were separately injected with miR-34a agomir, miR-34a agomir NC, si-CD47 and si- CD47 NC before their spinal cord tissues were collected for terminal-deoxynucleoitidyl Transferase Mediated nick end labeling (TUNEL) staining. Expressions of miR-34a, si-CD47, apoptosis related proteins and AKT pathway related proteins were measured by quantitative reverse transcription- polymerase chain reaction (qRT-PCR) and western blot.

RESULTS

SCI rat models were successfully established evidenced by decreased BBB scores and HE staining. Injection of miR-34a agomir and/or si-CD47 could suppress neuron cell apoptosis, with deceased apoptotic index (AI) and pro-apoptotic protein (cleaved caspase-3 and Bax) levels, and increased expressions of anti-apoptotic proteins (Bcl-2 and Mcl-1). Phosphorylated levels of phatidylinositol 3-kinase (PI3K) and AKT were further increased in rats injected with miR-34a agomir and si-CD47, compared with miR-34a agomir or si-CD47 injection alone.

CONCLUSION

MiR-34a can downregulate CD47 expression to activate PI3K/AKT signal pathway, and thus inhibit SCI induced spinal neuron apoptosis.

Serum exosomal microRNA transcriptome profiling in subacute spinal cord injured rats

MicroRNAs (miRNAs) are involved in a series of pathology of spinal cord injury (SCI). Although, locally expressed miRNAs have advantages in studying the pathological mechanism, they cannot be used as biomarkers. The "free circulation" miRNAs can be used as biomarkers, but they have low concentration and poor stability in body fluids. Exosomal miRNAs in body fluids have many advantages comparing with free miRNAs. Therefore, we hypothesized that the specific miRNAs in the central nervous system might be transported to the peripheral circulation and concentrated in exosomes after injury. Using next-generation sequencing, miRNA profiles in serum exosomes of sham and subactue SCI rats were analyzed. The results showed that SCI can lead to changes of serum exosomal miRNAs. These changed miRNAs and their associated signaling pathways may explain the pathological mechanism of suacute SCI. More importantly, we found some valuable serum exosomal miRNAs for diagnosis and prognosis of SCI.

MicroRNA‑15a‑5p‑targeting oncogene YAP1 inhibits cell viability and induces cell apoptosis in cervical cancer cells

MicroRNAs (miRNAs) have been reported to have important regulatory roles in the progression of several types of cancer, including cervical cancer (CC). However, the biological roles and regulatory mechanisms of miRNAs in CC remain to be fully elucidated. The aim of the present study was to examine the functions of miRNAs in CC and the possible mechanisms. Using a microarray, it was identified that miRNA-15a-5p (miR-15a-5p) was one of the most down-regulated miRNAs in CC tissues compared with adjacent noncancerous tissues. The low expression of miR-15a-5p was observed in CC tumor tissues with distant metastasis and in CC cell lines. In addition, the effects of miR-15a-5p upregulation on cell viability, apoptosis, invasion and migration of CC cells were investigated using CCK-8, flow cytometry, Transwell and wound healing assays, respectively. It was demonstrated that upregulation of miR-15a-5p significantly suppressed the viability, migration and invasion, and promoted the apoptosis of SiHa and C-33A cells. Furthermore, yes-associated protein 1 (YAP1), a well-known oncogene, was confirmed to be directly targeted by miR-15a-5p and was found to be negatively regulated by miR-15a-5p. Further correlation analysis indicated that miR-15a-5p expression was negatively correlated with YAP1 expression in CC tissues. Notably, overexpression of YAP1 abrogated the tumor suppressive effects of miR-15a-5p in CC cells. Taken together, these present findings indicated that the miR-15a-5p/YAP1 axis may provide a novel strategy for the clinical treatment of CC.

Silencing of microRNA-494 inhibits the neurotoxic Th1 shift via regulating HDAC2-STAT4 cascade in ischaemic stroke

BACKGROUND AND PURPOSE

T helper cell 1 (Th1)-skewed neurotoxicity contributes to the poor outcome of stroke in rodents. Here, we have elucidated the mechanism of the Th1/Th2 shift in acute ischaemic stroke (AIS) patients at hyperacute phase and have looked for a miRNA-based therapeutic target.

EXPERIMENTAL APPROACH

MiR-494 levels in blood from AIS patients and controls were measured by real-time PCR. C57BL/6J mice were subjected to transient middle cerebral artery occlusion, and cortical neurons were subjected to oxygen-glucose deprivation. Luciferase reporter system, chromatin immunoprecipitation sequencing (ChIP-Seq), and ChIP-PCR were used to uncover possible mechanisms.

KEY RESULTS

In lymphocytes from AIS patients, there was a Th1/Th2 shift and histone deacetylase 2 (HDAC2) was markedly down-regulated. ChIP-seq showed that HDAC2 binding sites were enriched in regulation of Th1 cytokine production, and ChIP-PCR confirmed that HDAC2 binding was changed at the intron of STAT4 and the promoter of T-box transcription factor 21 (T-bet) in lymphocytes from AIS patients. MiR-494 was the most significantly increased miRNA in lymphocytes from AIS patients, and miR-494-3p directly targeted HDAC2. A strong association existed between miR-494 and Th1 cytokines, and neurological deficit as measured by the National Institute of Health Stroke Scale (NIHSS) in AIS patients. In vitro and in vivo experiments showed that antagomir-494 reduced Th1 shift-mediated neuronal and sensorimotor functional damage in the mouse model of ischaemic stroke, via the HDAC2-STAT4 pathway.

CONCLUSION AND IMPLICATIONS

We demonstrated that miR-494 inhibition prevented Th1-skewed neurotoxicity through regulation of the HDAC2-STAT4 cascade.

Targeting CARD6 attenuates spinal cord injury (SCI) in mice through inhibiting apoptosis, inflammation and oxidative stress associated ROS production

Spinal cord injury (SCI) causes long-term and severe disability, influencing the quality of life and triggering serious socioeconomic consequences. Lack of effective pharmacotherapies for SCI is largely attributable to an incomplete understanding of its pathogenesis. Caspase recruitment domain family member 6 (CARD6) was initially suggested to be a protein playing significant role in NF-κB activation. However, the effects of CARD6 on SCI progression remain unknown. In this study, the wild type (CARD6+/+), CARD6 knockout (CARD6-/-) and CARD6 transgenic (TG) mice were subjected to a SCI model in vivo, and in vitro experiments were conducted by treating microglia cells with lipopolysaccharide (LPS). Here, we identified CARD6 as a suppressor of SCI in mice. CARD6 knockout significantly accelerated functional deficits, neuron death and glia activation, whereas CARD6 overexpression resulted in the opposite effects. Both in vivo and in vitro SCI models suggested that CARD6 knockout markedly promoted apoptosis by increasing Cyto-c release to cytosol from mitochondria and activating Caspase-3 signaling. In addition, CARD6 knockout mice exhibited stronger inflammatory response after SCI, as evidenced by the significantly elevated expression of pro-inflammatory cytokines TNF-α, IL-1β and IL-6, which was largely through enhancing the activation of NF-κB signaling.

Serum exosomal microRNA transcriptome profiling in subacute spinal cord injured rats

MicroRNAs (miRNAs) are involved in a series of pathology of spinal cord injury (SCI). Although, locally expressed miRNAs have advantages in studying the pathological mechanism, they cannot be used as biomarkers. The "free circulation" miRNAs can be used as biomarkers, but they have low concentration and poor stability in body fluids. Exosomal miRNAs in body fluids have many advantages comparing with free miRNAs. Therefore, we hypothesized that the specific miRNAs in the central nervous system might be transported to the peripheral circulation and concentrated in exosomes after injury. Using next-generation sequencing, miRNA profiles in serum exosomes of sham and subactue SCI rats were analyzed. The results showed that SCI can lead to changes of serum exosomal miRNAs. These changed miRNAs and their associated signaling pathways may explain the pathological mechanism of suacute SCI. More importantly, we found some valuable serum exosomal miRNAs for diagnosis and prognosis of SCI.

MicroRNA-494 Inhibits the LRG1 Expression to Induce Proliferation and Migration of VECs in Rats following Myocardial Infarction

Myocardial infarction (MI) is a life-threatening cardiac event that results in extreme damage to the heart muscle. The Wnt signaling pathway has been implicated in the development of heart diseases. Hence, the current study aimed to investigate the role of microRNA (miRNA) in association with the Wnt signaling pathway to identify potential candidates for MI therapy. Differentially expressed miRNAs associated with MI occurrence were screened, and miR-494 was selected for subsequent experiments. Sprague-Dawley rats were included to establish a MI model via intraperitoneal injection of 0.1 mg/kg atropine sulfate and 40 mg/kg pentobarbital sodium. Then, the interaction between miR-494 and LRG1 was identified. The effect of miR-494 on expression of the Wnt signaling pathway-related genes, proliferation, migration, and invasion ability of fibroblasts and vascular endothelial cells (VECs) was subsequently evaluated through a series of gain- and loss-of-function experiments. The results revealed that miR-494 was poorly expressed and LRG1 was highly expressed in MI rats. miR-494 targets and downregulates LRG1, which resulted in the inactivation of the Wnt signaling pathway and promoted proliferation, migration, and invasion ability of fibroblasts and VECs. In conclusion, this study provided evidence suggesting that overexpressed miR-494 could potentially promote the proliferation, migration, and invasion of fibroblasts and VECs in MI through the inactivation of the Wnt signaling pathway by binding to LRG1.

Inhibition of histone deacetylase 3 by MiR-494 alleviates neuronal loss and improves neurological recovery in experimental stroke

HDAC3 is an essential negative regulator of neuronal plasticity and memory formation. Although a chemical inhibitor has been invented, little is known about its endogenous modulators. We explored whether miR-494 affects HDAC3-mediated neuronal injury following acute ischemic stroke. A substantial increase in plasma miR-494 was detected in AIS patients and was positively associated with the mRS at one year after symptom onset. The miR-494 levels were transiently increased in the infarcted brain tissue of mice. In contrast, miR-494 levels were reduced in neurons but increased in the medium after OGD. Intracerebroventricular injection of miR-494 agomir reduced neuronal apoptosis and infarct volume at the acute stage of MCAO, promoted axonal plasticity and long-term outcomes at the recovery stage, suppressed neuronal ataxin-3 and HDAC3 expression and increased acetyl-H3K9 levels in the ipsilateral hemisphere. In vitro studies confirmed that miR-494 posttranslationally inhibited HDAC3 in neurons and prevented OGD-induced neuronal axonal injury. The HDAC3 inhibitor increased acetyl-H3K9 levels and reversed miR-494 antagomir-aggravated acute cerebral ischemic injury, as well as brain atrophy and long-term functional recovery. These results suggest that miR-494 may serve as a predictive biomarker of functional outcomes in AIS patients and a potential therapeutic target for the treatment of ischemic stroke.

Silica nanoparticles induce spermatocyte cell autophagy through microRNA-494 targeting AKT in GC-2spd cells

Researches had shown that silica nanoparticles (SiNPs) could reduce the quantity and quality of sperms. However, chronic effects of SiNPs have not been well addressed. In this study, mice spermatocyte cells (GC-2spd cells) were continuously exposed to SiNPs (5 μg/mL) for 30 passages and then the changes of microRNA (miRNA) profile and mRNA profile were detected. The function of miRNAs was verified by inhibitors to explore the regulation role of miRNAs in reproductive toxicity induced by SiNPs. The results showed that SiNPs induced cytotoxicity, and activated autophagy in GC-2spd cells. SiNPs led to a total of 1604 mRNAs (697 up-regulated and 907 down-regulated) and 15 miRNAs (6 up-regulated such as miRNA-138 and miRNA-494 and 9 down-regulated) with different expression in GC-2spd cells. The combined miRNA profile and mRNA profile showed that 415 mRNAs with different expression in 5 μg/mL SiNPs group were regulated by miRNA. Furthermore, our study demonstrated that SiNPs decreased the expressions of AKT mRNAs. Moreover, SiNPs had an activation effect on the AMPK/TSC/mTOR pathway. However, inhibitor of miRNA-494 could attenuate the expression levels of AMPK, TSC, LC3Ⅱ and alleviate the decreased of AKT, mTOR, p-mTOR induced by SiNPs. The above results suggested that the low-dose SiNPs exposure could promote autophagy by miRNA-494 targeting AKT, thereby activating AMPK/TSC/mTOR pathway in GC-2spd cells. MiRNA-494 is an important regulator of autophagy by targeting AKT, which provides new evidence for the male reproductive toxicity mechanism of SiNPs.

MicroRNA-26b inhibits oligodendrocyte precursor cell differentiation by targeting adrenomedullin in spinal cord injury

Oligodendrocyte precursor cells (OPCs) serve as a reservoir of newborn oligodendrocytes (OLs) in pathological and homeostatic conditions. After spinal cord injury (SCI), OPCs are activated to generate myelinating OLs, contributing to remyelination and functional recovery; however, the underlying molecular mechanisms remain unclear. Here, microRNA-26b (miR-26b) expression in the spinal cord tissues of SCI rats was examined by real-time polymerase chain reaction analysis. The influences of miR-26b on locomotor recovery following SCI were assessed utilizing Basso, Beattie, and Bresnahan (BBB) scores. The effects of miR-26b on OPC differentiation were explored using immunofluorescence and western blot analyses in vitro and in vivo. The potential targets that are modulated by miR-26b were identified by bioinformatics, luciferase reporter assays, and western blot analyses. The effects of adrenomedullin (ADM) on OPC differentiation were explored in vitro using immunofluorescence and western blot analyses. We demonstrated that miR-26b was significantly downregulated after SCI. BBB scores showed that miR-26b exacerbated the locomotor function deficits induced by SCI. In vitro, miR-26b inhibited the differentiation of primary rat OPCs. In vivo, miR-26b suppressed OPC differentiation in SCI rats. Bioinformatics analyses and experimental detection revealed that miR-26b directly targeted ADM in OPCs. In addition, knockdown of ADM suppressed the differentiation of primary rat OPCs. Our study provides evidence that ADM may mediate miR-26b-inhibited OPC differentiation in SCI.

Effect of M2 macrophage adoptive transfer on transcriptome profile of injured spinal cords in rats

The previous studies showed that alternatively activated anti-inflammatory macrophage (M2) adoptive immunity can improve the proportion of local M2 cells and play the neuroprotective effect after spinal cord injury (SCI). Its molecular mechanism is not yet very clear. Therefore, this study aims to analyze the effect of the M2 adoptive transfer on the local expression of gene transcription. Sprague-Dawley (SD) rats were used for culture of macrophages and establishment of SCI models. After SCI, the polarized M2 macrophages were transferred to the injured rats by tail vein injection. Seven days after operation, the differentially expressed genes (DEGs) in the spinal cords were analyzed by RNA-sequencing (RNA-Seq). Then, the functional enrichment analysis and pathways were performed by using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), respectively. RNA-Seq showed that M2 adoptive immunity can down-regulate many well-studied gene expressions associated with signaling pathways of inflammatory, such as antigen processing and presentation, phagosome, cell adhesion molecules, natural killer cell-mediated cytotoxicity, endocytosis, proteasome, and Toll-like receptor signaling pathway. These may explain the mechanism of our previous adoptive immunization of M2 cells to provide neuroprotection for SCI. In addition, a novel pathway, retinoic acid-inducible gene-1 (RIG-I)-like receptor signaling pathway was found to be involved in the pathological process of SCI and the response to M2 adoptive immunity as well. This will provide a new explanation for the pathological mechanism of SCI and a new theoretical and experimental basis for its clinical treatment. The raw Illumina data are available at http://www.ncbi.nlm.nih.gov/sra (accession number PRJNA517238).

Impact statement

This research aimed to analyze the effect of M2 macrophage adoptive transfer on the local expression of gene transcription after SCI by RNA-Seq. The results showed that M2 adoptive immunity can down-regulate many well-studied gene expressions associated with signaling pathways of inflammatory. These may explain the mechanism of our previous adoptive immunization of M2 cells to provide neuroprotection for SCI. In addition, a novel pathway, RIG-I-like receptor signaling pathway was also found to involve in the pathological process of SCI and the response to M2 adoptive immunity. This will provide a new explanation for the pathological mechanism of SCI and a new theoretical and experimental basis for its clinical treatment.

Tackling Aging by Using miRNA as a Target and a Tool

miRNA is a class of short noncoding RNA that regulates gene expression at the post-transcriptional level. Evidence of age-associated changes in miRNA expression has been collected in models ranging from nematodes to humans; however, there has been little discussion of how to turn our knowledge of miRNA biology into antiaging therapy. This opinion article provides a snapshot of our current understanding of the roles of miRNA in modulating the aging process. We discuss major chemical techniques for modifying the miRNA structure as well as developing delivery systems for intervention. Finally, technical needs to be met for bench-to-clinic translation of miRNA-based interventions are highlighted for future research.

Progesterone Effects in the Nervous System

The sex hormone progesterone is mainly known as a key factor in establishing and maintaining pregnancy. In addition, progesterone has been shown to induce morphological changes in the central and peripheral nervous system by increasing dendrito-, spino-, and synaptogenesis in Purkinje cells (Wessel et al.: Cell Mol Life Sci (2014a) 1723-1740) and increasing axonal outgrowth in dorsal root ganglia (Olbrich et al.: Endocrinology (2013) 3784-3795). These effects mediated mainly by the classical progesterone receptors (PRs) A and B seem to be limited to young neurons. It may be assumed that microRNAs (miRNAs), which are potent regulators of nervous system maturation and degeneration, are also involved in the regulation of progesterone-mediated neuronal plasticity by altering the expression patterns of the corresponding PR A/B receptors (Theis and Theiss: Neural Regen Res (2015) 547-549, Pieczora et al.: Cerebellum (2017) 376-387). This review critically discusses current data on the neuroprotective effect of progesterone and its corresponding receptors in the nervous system, with possible regulatory processes by miRNAs. Preclinical studies on stroke and traumatic brain injury revealed neuroprotective and neuroregenerative effects of progesterone in the treatment of severe neurological diseases in animal models, but have so far failed in humans. In this context, the identification of specific miRNAs that regulate the expression of progesterone and PR could help to exploit the neuroprotective potential of progesterone for the treatment of various neurological disorders. Anat Rec, 302:1276-1286, 2019. © 2019 Wiley Periodicals, Inc.

MicroRNA‑494 inhibits apoptosis of murine vascular smooth muscle cells in vitro

Apoptosis of vascular smooth muscle cells (VSMCs) is a process that regulates vessel remodeling in various cardiovascular diseases. The specific mechanisms that control VSMC apoptosis remain unclear. The present study aimed to investigate whether microRNA‑494 (miR‑494) is involved in regulating VSMC apoptosis and its underlying mechanisms. Cell death ELISA and terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labeling assays were used to detect apoptosis of murine VSMCs following stimulation with tumor necrosis factor‑α (TNF‑α). The results indicated that TNF‑α upregulated VSMC apoptosis in a dose‑dependent manner. Microarray analysis was used to evaluate the expression profile of microRNAs following TNF‑α stimulation in murine VSMCs. The expression of miR‑494 was downregulated, whereas B‑cell lymphoma-2‑like 11 (BCL2L11) protein expression levels were upregulated in VSMCs following treatment with TNF‑α. Luciferase reporter assays confirmed that BCL2L11 was a direct target of miR‑494. Transfection with miR‑494 mimics decreased VSMC apoptosis and downregulated BCL2L11 protein levels. Conversely, transfection with miR‑494 inhibitors increased cell apoptosis and upregulated BCL2L11 protein levels, suggesting that miR‑494 may function as an essential regulator of BCL2L11. The increase in apoptosis caused by miR‑494 inhibitors was abolished in cells co‑transfected with BCL2L11‑targeting small interfering RNA. The findings of the present study revealed that miR‑494 inhibited TNF‑α‑induced VSMC apoptosis by downregulating the expression of BCL2L11.

MicroRNAs in contusion spinal cord injury: pathophysiology and clinical utility

Spinal cord injury (SCI) in humans is a common central nervous system trauma. Pathophysiologically, SCI involves both primary and secondary damages. Therapeutically, targeting secondary damage including inflammation, neuropathic pain, apoptosis, demyelination, and glial reaction to promote functional benefits for SCI patients has long been considered a potential treatment strategy by neuroscientists and clinicians. As a type of small non-coding RNA, microRNAs (miRNAs) have been shown to play essential roles in the regulation of pathophysiologic processes of SCI and are considered to be an effective treatment method for SCI. Dysregulated expression of miRNAs is observed in SCI patients and animal models of SCI. Furthermore, miRNAs might also be used as biomarkers for diagnostic and prognostic purposes in SCI. Given contusion injury is the most clinically relevant type of SCI, this review mainly focuses on the role of miRNAs in the pathophysiology of contusion SCI and the putative utilization of miRNAs as diagnostic biomarkers and therapeutic targets for contusion SCI.

Circular RNA Expression Alteration and Bioinformatics Analysis in Rats After Traumatic Spinal Cord Injury

Spinal cord injury (SCI) is mostly caused by trauma. As primary mechanical injury is unavoidable in SCI, a focus on the pathophysiology and underlying molecular mechanisms of SCI-induced secondary injury is necessary to develop promising treatments for SCI patients. Circular RNAs (circRNAs) are associated with various diseases. Nevertheless, studies to date have not yet determined the functional roles of circRNAs in traumatic SCI. We examined circRNA expression profiles in the contused spinal cords of rats using microarray and quantitative reverse transcription-PCR (qRT-PCR) then predict their potential roles in post-SCI pathophysiology with bioinformatics. We found a total of 1676 differentially expressed circRNAs (fold change ≥ 2.0; P < 0.05) in spinal cord 3 days after contusion using circRNA microarray; 1261 circRNAs were significantly downregulated, whereas the remaining 415 were significantly upregulated. Then, five selected circRNAs, namely, rno_circRNA_005342, rno_circRNA_015513, rno_circRNA_002948, rno_circRNA_006096, and rno_circRNA_013017 were all significantly downregulated in the SCI group after verification by qRT-PCR, demonstrating a similar expression pattern in both microarray and PCR data. The next section of the study was concerned with the prediction of circRNA/miRNA/mRNA interactions using bioinformatics analysis. In the final part of the study, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses indicated carbohydrate metabolic process was one of the most significant enrichments and meaningful terms after GO analysis, and the top two signaling pathways affected by the circRNAs-miRNAs axes were the AMP-activated protein kinase signaling pathway and the peroxisome related pathway. In summary, this study showed an altered circRNA expression pattern that may be involved in physiological and pathological processes in rats after traumatic SCI, providing deep insights into numerous possibilities for SCI treatment targets by regulating circRNAs.

MicroRNA-494-3p protects rat cardiomyocytes against septic shock via PTEN

The aim of the present study was to investigate the role of microRNA (miR)-494-3p in myocardial injury in patients with septic shock and the underlying mechanism. A total of 22 patients with sepsis and 17 patients with septic shock were included in the present study. In addition, 20 healthy subjects were recruited as the control group. Peripheral blood was collected from all subjects and a rat cardiomyocyte model of myocardial injury was constructed. Reverse transcription-quantitative polymerase chain reaction was used to measure miR-494-3p expression, while cell counting kit-8 assays were performed to assess cell proliferation. Flow cytometry was performed to investigate cell cycle distribution and apoptosis. Lactate dehydrogenase (LDH) assays were performed to measure LDH levels. ELISA was also performed to measure LDH, tumor necrosis factor (TNF)-α and interleukin (IL)-6 levels in cell culture supernatants. Western blotting was employed to detect phosphatase and tensin homolog (PTEN) protein expression and dual luciferase reporter assays were performed to identify the interaction between miR-494-3p and PTEN mRNA. Reduced miR-494-3p expression was correlated with myocardial damage in patients with septic shock. Sera from patients with septic shock downregulated miR-494-3p expression in rat cardiomyocytes. miR-494-3p overexpression inhibited rat cardiomyocyte injury induced by treatment with sera from patients with septic shock. Furthermore, miR-494-3p overexpression reduced the synthesis and release of TNF-α and IL-6 from rat cardiomyocytes. PTEN knockdown alleviated rat cardiomyocyte injury following treatment with serum from patients with septic shock. PTEN was demonstrated to induce the release of TNF-α and IL-6 from rat cardiomyocytes treated with septic shock serum, while miR-494-3p was demonstrated to bind to the 3′-untranslated seed region of PTEN mRNA to regulate its expression. The results of the present study suggest that miR-494-3p is downregulated in the peripheral blood of patients with septic shock and is negatively correlated with myocardial injury. The present study also indicates that miR-494-3p regulates PTEN expression, inhibits sepsis-induced myocardial injury and protects the function of cardiomyocytes. The protective effect and mechanism of action of miR-494-3p indicate that it has potential for use in the clinical diagnosis and therapy of myocardial damage.