miR-27a promotion resulting from silencing of HDAC3 facilitates the recovery of spinal cord injury by inhibiting PAK6 expression in rats

Identification and Validation of Synapse-related Hub Genes after Spinal Cord Injury by Bioinformatics Analysis

BACKGROUND

Spinal cord injury (SCI) is a neurological disease with high morbidity and mortality. Previous studies have shown that abnormally expressed synapse-related genes are closely related to the occurrence and development of SCI. However, little is known about the interaction of these aberrantly expressed genes and the molecular mechanisms that play a role in the injury response. Therefore, deeply exploring the correlation between synapse-related genes and functional recovery after spinal cord injury and the molecular regulation mechanism is of great significance.

METHODS

First, we selected the function GSE45006 dataset to construct three clinically meaningful gene modules by hierarchical clustering analysis in 4 normal samples and 20 SCI samples. Subsequently, we performed functional and pathway enrichment analyses of key modules.

RESULTS

The results showed that related module genes were significantly enriched in synaptic structures and functions, such as the regulation of synaptic membranes and membrane potential. A protein-protein interaction network (PPI) was constructed to identify 10 hub genes of SCI, and the results showed that Snap25, Cplx1, Stxbp1, Syt1, Rims1, Rab3a, Syn2, Syn1, Cask, Lin7b were most associated with SCI. Finally, these hub genes were further verified by quantitative real-time fluorescence polymerase chain reaction (qRT-PCR) in the spinal cord tissues of the blank group and SCI rats, and it was found that the expression of these hub genes was significantly decreased in the spinal cord injury compared with the blank group (P ≤ 0.05).

CONCLUSION

These results suggest that the structure and function of synapses play an important role after spinal cord injury. Our study helps to understand the underlying pathogenesis of SCI patients further and identify new targets for SCI treatment.

Electroacupuncture-Modulated MiR-106b-5p Expression Enhances Autophagy by Targeting Beclin-1 to Promote Motor Function Recovery After Spinal Cord Injury in Rats

OBJECTIVE

Electroacupuncture (EA) has a definite effect on the treatment of spinal cord injuries (SCIs), but its underlying molecular mechanism remains unclear. Meanwhile, MiR106b-5p is an autophagy- and apoptosis-related microribonucleic acid, but whether it regulates the progression of autophagy and apoptosis in SCIs is yet undetermined. As such, this study aimed to elucidate the involvement of miR-106b-5p in the EA treatment of an SCI.

METHODS

The miR-106b-5p level was detected by quantitative real-time polymerase chain reaction. In vitro, SH-SY5Y cells were transfected with miR-106b-5p mimics or inhibitors to regulate the miR-106b-5p expression, while in vivo, SCI rats were treated with EA for 7 days at the bilateral Zusanli (ST36) and Jiaji (EX-B2) acupoints. The motor function was evaluated using the Basso-Beattie-Bresnahan (BBB) criteria. Further, autophagic vacuoles, pathological damage, and neuronal cell morphology were observed by transmission electron microscopy, as well as by hematoxylin and eosin and Nissl staining, respectively.

RESULTS

The miR-106b-5p level, which can interact directly with Beclin-1 by influencing its expression, as well as the expressions of P62, Caspase-3, and Bax, was upregulated after an SCI, but it decreased after EA. Moreover, the ratio of LC3-II to LC3-I was upregulated after EA. EA can enhance autophagy, reduce neuronal apoptosis, and minimize motor dysfunction and histopathological deficits after an SCI. More importantly, however, all the above effects induced by EA can be reversed after an injection of miR-106-5p agomir to produce an overexpression of miR-106b-5p.

CONCLUSION

EA treatment could downregulate miR-106b-5p to alleviate SCI-mediated injuries by promoting autophagy and inhibiting apoptosis.

The role of the miR-4306/PAK6 axis in degenerative nucleus pulposus cells in human intervertebral disc degeneration

Intervertebral disc degeneration (IDD), characterized by degenerative changes that occur in intervertebral discs due to aging or structural injury, is thought to be the most common cause of lower back pain. Recent studies have shown that microRNAs (miRNAs) have a critical role in the etiopathogenesis of IDD. In the current study, we aimed to determine the role of miRNAs in mediating the underlying mechanisms associated with IDD. First, differentially expressed miRNAs (DEmiRNAs) were identified using the GEO database, and subsequently confirmed by RT-qPCR and in situ hybridization. We found that miR-4306 expression was significantly decreased in human nucleus pulposus (NP) tissues compared with healthy controls, and was negatively correlated with the patients' Pfirrmann grade. To determine the mechanism by which miR-4306 was involved in IDD pathogenesis, we examined the effects of overexpressing or silencing miR-4306 on extracellular matrix (ECM) synthesis/degradation, proliferation, autophagy and apoptosis of human degenerated NP cells isolated from IDD patients. Next, we used dual-luciferase reporter assays to demonstrate that miR-4306 interacted with the 3'-untranslated regions of p21-activated kinase 6 (PAK6) mRNA, resulting in significant suppression of PAK6 expression. This effect was abolished by miR-4306 binding site mutations. Using miR-4306/PAK6 gain-of-function and loss-of-function studies in human degenerated NP cells, we demonstrated that miR-4306 promoted NP cell proliferation, ECM synthesis and autophagy, while inhibiting apoptosis and ECM degradation via PAK6. Thus, our findings indicate that miR-4306, acting via PAK6, has an important role in IDD and can be used as a promising therapeutic target for the treatment of patients with IDD.

ISGylation is induced in neurons by demyelination driving ISG15-dependent microglial activation

The causes of grey matter pathology and diffuse neuron injury in MS remain incompletely understood. Axonal stress signals arising from white matter lesions has been suggested to play a role in initiating this diffuse grey matter pathology. Therefore, to identify the most upstream transcriptional responses in neurons arising from demyelinated axons, we analyzed the transcriptome of actively translating neuronal transcripts in mouse models of demyelinating disease. Among the most upregulated genes, we identified transcripts associated with the ISGylation pathway. ISGylation refers to the covalent attachment of the ubiquitin-like molecule interferon stimulated gene (ISG) 15 to lysine residues on substrates targeted by E1 ISG15-activating enzyme, E2 ISG15-conjugating enzymes and E3 ISG15-protein ligases. We further confirmed that ISG15 expression is increased in MS cortical and deep gray matter. Upon investigating the functional impact of neuronal ISG15 upregulation, we noted that ISG15 expression was associated changes in neuronal extracellular vesicle protein and miRNA cargo. Specifically, extracellular vesicle-associated miRNAs were skewed toward increased frequency of proinflammatory and neurotoxic miRNAs and decreased frequency of anti-inflammatory and neuroprotective miRNAs. Furthermore, we found that ISG15 directly activated microglia in a CD11b-dependent manner and that microglial activation was potentiated by treatment with EVs from neurons expressing ISG15. Further study of the role of ISG15 and ISGylation in neurons in MS and neurodegenerative diseases is warranted.

HDAC3 Inhibition Alleviates High-Glucose-Induced Retinal Ganglion Cell Death through Inhibiting Inflammasome Activation

Purpose

The exact effects of histone deacetylase 3 (HDAC3) inhibition in DR related retinal ganglion cells (RGCs) death remained unclear. This study is aimed at detecting the influence of HDAC3 on the high-glucose-induced retinal ganglion cell death.

Methods

The retinal HDAC3 expression in DR of different time points was analyzed by immunohistochemical assay and western blot. Besides, the expression of HDAC3 and both retinal thickness and RGC loss were analyzed. The effects of HDAC3 inhibitor on cell viability, oxidative stress, and apoptosis in high-glucose- (HG-) treated RGCs were analyzed. Both inflammatory and antioxidative factors were detected by ELISA.

Results

Advanced effects of HDAC3 inhibition on the expression of NLRP3 inflammasome were detected using western blots. High HDAC3 expression was detected only in the late DR mice (4 months of diabetes duration) but not early DR mice (2 months of diabetes duration). The immunohistochemical assay showed that HDAC3 expression was correlated with both retinal thickness and RCG contents. HDAC3 inhibitor significantly protected the HG-treated RGCs from damaged cell viability, severe apoptosis, and oxidative stress. Advanced pathway analyses showed that HDAC3 inhibition inactivated NLRP3 inflammasome and thus alleviated retinal inflammation. Conclusion. In conclusion, HDAC3 was involved in RGC loss and thus promoted the progression of neurodegeneration of DR. Besides, HDAC3 inhibitor demonstrated protective effects in neurodegeneration in DR through downregulation of NLRP3 activity. The effects of HDAC3 inhibitor in DR management should be confirmed in clinical trials.

The protective effect of MiR-27a on the neonatal hypoxic-ischemic encephalopathy by targeting FOXO1 in rats

BACKGROUND

Neonatal hypoxic-ischemic encephalopathy (HIE), a kind of hypoxic-ischemic brain damage caused by perinatal asphyxia, is the most crucial cause of neonatal death and long-term neurological dysfunction in children. We aimed to investigate the protective effects of micro (mi)R-27a on HIE in neonatal rats.

METHODS

A rat model of neonatal HIE was constructed by modification of the Rice-Vannucci model. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to test the expressions of miR-27a, FOXO1 messenger RNA (mRNA), interleukin-1β (IL-1β) mRNA, and tumor necrosis factor-α (TNF-α) mRNA, and western blot was applied to test the expression of FOXO1. In order to overexpress miR-27a, an intracerebroventricular injection (i.c.v) of miR-27a mimic was administered. We adopted 2,3,5-triphenytetrazolium chloride (TTC) staining and brain water content measurement to test the effects of miR-27a on the infarcted volume and edema in brain after HIE. Flow cytometry (FCM) analysis was applied to test the effects of miR-27a on the infiltrated peripheral immune cells in the rat brains after HIE.

RESULTS

We successfully established a rat model of neonatal HIE. It was revealed that the expressions of miR-27a decreased gradually after HIE, however, the expressions of FOXO1 mRNA increased. After injection of the miR-27a mimic, the expression of miR-27a in the rat HIE model brains was significantly upregulated, however, the expression of FOXO1 was robustly downregulated. Both TTC staining and brain water content showed that the infarcted volume and brain edema was markedly increased after HIE. Interestingly, the overexpression of miR-27a reduced the infarcted volume and edema induced by HIE. Additionally, RT-qPCR and FCM analysis showed that HIE lead to increases of IL-1β, TNF-α, and infiltrated immune cells. Overexpression of miR-27a could reduce the expressions of IL-1β mRNA and TNF-α mRNA, and the cell numbers of infiltrated peripheral macrophages and neutrophils in the brain.

CONCLUSIONS

MiR-27a plays protective roles by reducing infarct volume and brain edema, and inhibiting inflammatory factors and infiltrated peripheral immune cells by targeting FOXO1 in neonatal HIE rats.

Histone deacetylase HDAC2 regulates microRNA-125a expression in neuroblastoma

BACKGROUND

Neuroblastoma (NB) is an infrequent childhood malignancy of the peripheral sympathetic nervous system and is accountable for about 10% of pediatric tumors. microRNA (miR)-125a has been implicated to serve as a tumor suppressor in various cancers. Herein, we set out to ascertain whether miR-125a exerts antitumor effects in NB.

METHODS

Downregulated miRNAs were identified by miRNA microarray analysis of NB tissues and paracancerous tissues. The expression of miR-125a in NB tissues and cells was detected by reverse transcription-quantitative (RT-q) PCR, followed by prognostic analysis. Gene Ontology (GO) enrichment analysis was performed on target genes of differentially expressed miRNAs. Cell proliferation, apoptosis, and differentiation were detected by cell counting kit-8 (CCK-8), Hoechst staining, immunofluorescence, and western blot. NB cells were injected into nude mice to detect tumorigenic, apoptotic, and differentiation activities in vivo. Dual-luciferase assay and chromatin immunoprecipitation (ChIP) were carried out to verify the binding relationship between miR-125a and PHOX2B or histone deacetylases 2 (HDAC2), respectively. Finally, rescue experiments were conducted.

RESULTS

miR-125a was downregulated in NB tissues and cells, which was associated with poor prognosis. miR-125a reduced NB cell proliferation and augmented apoptosis and differentiation. NB cells with miR-125a overexpression decreased cell tumorigenesis and increased apoptosis and differentiation in xenograft tumor tissues. miR-125a targeted PHOX2B, which was highly expressed in NB tissues and cells. HDAC2, highly expressed in NB tissues and cells, repressed miR-125a transcription through histone deacetylation. Overexpression of HDAC2 or PHOX2B rescued the effects of miR-125a on NB cell proliferation, apoptosis, and differentiation.

CONCLUSION

HDAC2 inhibited miR-125a transcription through deacetylation, and miR-125a suppressed NB development through binding to PHOX2B.

Entinostat Improves Motor Function and Neuronal Damage Via Downregulating NLRP3 Inflammasome Activation After Spinal Cord Injury

Background: Spinal cord injury (SCI), a major public health problem, has no effective treatment. A large number of studies have confirmed that histone deacetylases (HDACs) are involved in the physiologic processes that occur following SCI. We tried to uncover the potential neuroprotective role of entinostat (a class I HDAC inhibitor) in SCI.

Methods: We conducted a study on a preclinical mouse model of SCI and OGD-induced neuronal damage to present the role of entinostat by the analysis of motor function, histopathologic damage, local NLRP3 inflammasome activation, and neuronal damage.

Results: The results showed that entinostat suppressed HDAC activation (including HDAC1 and HDAC3 expression), improved the grip strength and BMS score, spinal edema, cell death, and local NLRP3 inflammasome activation in the spinal cord following SCI. Furthermore, entinostat significantly increased OGD-inhibited neuronal activity and decreased PI-positive cells, HDAC activation, caspase-1 activation, IL-1β and IL-18 levels, and NLRP3 expression.

Conclusion: In summary, we first documented that entinostat improved the motor function, histopathologic damage, and local inflammatory response and NLRP3 inflammasome activation in the spinal cord following SCI and also presented the neuroprotective role of OGD-induced neuronal damage via the NLRP3 inflammasome. Thus, our study has the potential to reveal the interaction between the HDAC and NLRP3 inflammasome in the pathologic process as well as SCI and further promote the clinical indications of HDACi entinostat and clinical treatment for the inflammatory response after SCI.

The critical roles of histone deacetylase 3 in the pathogenesis of solid organ injury

Histone deacetylase 3 (HDAC3) plays a crucial role in chromatin remodeling, which, in turn, regulates gene transcription. Hence, HDAC3 has been implicated in various diseases, including ischemic injury, fibrosis, neurodegeneration, infections, and inflammatory conditions. In addition, HDAC3 plays vital roles under physiological conditions by regulating circadian rhythms, metabolism, and development. In this review, we summarize the current knowledge of the physiological functions of HDAC3 and its role in organ injury. We also discuss the therapeutic value of HDAC3 in various diseases.

Astragaloside IV Reduces Cerebral Ischemia/Reperfusion-Induced Blood-Brain Barrier Permeability in Rats by Inhibiting ER Stress-Mediated Apoptosis

Background

Previous studies proved that AS-IV could prevent blood-brain barrier (BBB) against an increase in permeability. However, its underlying molecular mechanism has not been enlightened yet. The aim of the study is to reveal the potential protective mechanism of astragaloside IV (AS-IV) on the blood-brain barrier after ischemia-reperfusion.

Methods

In vivo, AS-IV neurological protection was measured by Long's five-point scale and 2,3,5-triphenyltetrazolium chloride staining. AS-IV protection for BBB was observed by Evans blue extravasation technique. Endoplasmic reticulum stress and apoptosis-related protein levels were measured by western blot with AS-IV intervention. In vitro, cell apoptosis was analyzed by western blot and flow cytometry.Endoplasmic reticulum stress-related protein levels were quantified through western blot.

Results

AS-IV treatment could decrease the infarct size in rats' brain and protect the BBB against Evans blue permeating through brain, after ischemia/reperfusion, significantly. Further, ischemia/reperfusion or oxygen-glucose deprivation/reperfusion was found to have an increase in endothelial cell apoptosis proteins, such as Bax, Bcl-2, and caspase-3, and endoplasmic reticulum stress-associated proteins, such as phosphorylated PERK and eIF2α, Bip, and CHOP, which were attenuated by AS-IV treatment.

Conclusions

AS-IV can effectively protect the blood-brain barrier and reduce the area of cerebral infarction via inhibiting endoplasmic reticulum stress-mediated apoptosis in endothelial cells.