SNHG12 inhibits oxygen‑glucose deprivation‑induced neuronal apoptosis via the miR‑181a‑5p/NEGR1 axis

Neuronal Responses to Ischemia: Scoping Review of Insights from Human-Derived In Vitro Models

Translation of neuroprotective treatment effects from experimental animal models to patients with cerebral ischemia has been challenging. Since pathophysiological processes may vary across species, an experimental model to clarify human-specific neuronal pathomechanisms may help. We conducted a scoping review of the literature on human neuronal in vitro models that have been used to study neuronal responses to ischemia or hypoxia, the parts of the pathophysiological cascade that have been investigated in those models, and evidence on effects of interventions. We included 147 studies on four different human neuronal models. The majority of the studies (132/147) was conducted in SH-SY5Y cells, which is a cancerous cell line derived from a single neuroblastoma patient. Of these, 119/132 used undifferentiated SH-SY5Y cells, that lack many neuronal characteristics. Two studies used healthy human induced pluripotent stem cell derived neuronal networks. Most studies used microscopic measures and established hypoxia induced cell death, oxidative stress, or inflammation. Only one study investigated the effect of hypoxia on neuronal network functionality using micro-electrode arrays. Treatment targets included oxidative stress, inflammation, cell death, and neuronal network stimulation. We discuss (dis)advantages of the various model systems and propose future perspectives for research into human neuronal responses to ischemia or hypoxia.

Role of non-coding RNAs in neuroblastoma

Neuroblastoma is known as the most prevalent extracranial malignancy in childhood with a neural crest origin. It has been widely accepted that non-coding RNAs (ncRNAs) play important roles in many types of cancer, including glioma and gastrointestinal cancers. They may regulate the cancer gene network. According to recent sequencing and profiling studies, ncRNAs genes are deregulated in human cancers via deletion, amplification, abnormal epigenetic, or transcriptional regulation. Disturbances in the expression of ncRNAs may act either as oncogenes or as anti-tumor suppressor genes, and can lead to the induction of cancer hallmarks. ncRNAs can be secreted from tumor cells inside exosomes, where they can be transferred to other cells to affect their function. However, these topics still need more study to clarify their exact roles, so the present review addresses different roles and functions of ncRNAs in neuroblastoma.

Identification of programmed cell death-related gene signature and associated regulatory axis in cerebral ischemia/reperfusion injury

Background: Numerous studies have suggested that programmed cell death (PCD) pathways play vital roles in cerebral ischemia/reperfusion (I/R) injury. However, the specific mechanisms underlying cell death during cerebral I/R injury have yet to be completely clarified. There is thus a need to identify the PCD-related gene signatures and the associated regulatory axes in cerebral I/R injury, which should provide novel therapeutic targets against cerebral I/R injury.

Methods: We analyzed transcriptome signatures of brain tissue samples from mice subjected to middle cerebral artery occlusion/reperfusion (MCAO/R) and matched controls, and identified differentially expressed genes related to the three types of PCD(apoptosis, pyroptosis, and necroptosis). We next performed functional enrichment analysis and constructed PCD-related competing endogenous RNA (ceRNA) regulatory networks. We also conducted hub gene analysis to identify hub nodes and key regulatory axes.

Results: Fifteen PCD-related genes were identified. Functional enrichment analysis showed that they were particularly associated with corresponding PCD-related biological processes, inflammatory response, and reactive oxygen species metabolic processes. The apoptosis-related ceRNA regulatory network was constructed, which included 24 long noncoding RNAs (lncRNAs), 41 microRNAs (miRNAs), and 4 messenger RNAs (mRNAs); the necroptosis-related ceRNA regulatory network included 16 lncRNAs, 20 miRNAs, and 6 mRNAs; and the pyroptosis-related ceRNA regulatory network included 15 lncRNAs, 18 miRNAs, and 6 mRNAs. Hub gene analysis identified hub nodes in each PCD-related ceRNA regulatory network and seven key regulatory axes in total, namely, lncRNA Malat1/miR-181a-5p/Mapt, lncRNA Malat1/miR-181b-5p/Mapt, lncRNA Neat1/miR-181a-5p/Mapt, and lncRNA Neat1/miR-181b-5p/Mapt for the apoptosis-related ceRNA regulatory network; lncRNA Neat1/miR-181a-5p/Tnf for the necroptosis-related ceRNA regulatory network; lncRNA Malat1/miR-181c-5p/Tnf for the pyroptosis-related ceRNA regulatory network; and lncRNAMalat1/miR-181a-5p for both necroptosis-related and pyroptosis-related ceRNA regulatory networks.

Conclusion: The results of this study supported the hypothesis that these PCD pathways (apoptosis, necroptosis, pyroptosis, and PANoptosis) and crosstalk among them might be involved in ischemic stroke and that the key nodes and regulatory axes identified in this study might play vital roles in regulating the above processes. This may offer new insights into the potential mechanisms underlying cell death during cerebral I/R injury and provide new therapeutic targets for neuroprotection.

Long Non-Coding RNA-Mediated Competing Endogenous RNA Networks in Ischemic Stroke: Molecular Mechanisms, Therapeutic Implications, and Challenges

Ischemic stroke (IS) is a disease that is characterized by high mortality and disability. Recent studies have shown that LncRNA-mediated competing endogenous RNA (ceRNA) networks play roles in the occurrence and development of cerebral I/R injury by regulating different signaling pathways. However, no systematic analysis of ceRNA mechanisms in IS has been reported. In this review, we discuss molecular mechanisms of LncRNA-mediated ceRNA networks under I/R injury. The expression levels of LncRNAs, microRNAs (miRNAs), and messenger RNAs (mRNAs) and their effects in four major cell types of the neurovascular unit (NVU) are also involved. We further summarize studies of LncRNAs as biomarkers and therapeutic targets. Finally, we analyze the advantages and limitations of using LncRNAs as therapeutics for IS.

Long noncoding RNA small nucleolar RNA host gene 12/microRNA-138-5p/nuclear factor I/B regulates neuronal apoptosis, inflammatory response, and oxidative stress in Parkinson's disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder that causes tremors, gait rigidity, and hypokinesia. We determined the effects of long noncoding RNA small nucleolar RNA host gene 12 (lncRNA SNHG12) on the development of PD. StarBase analysis and dual-luciferase reporter assay verified the interaction between lncRNA SNHG12 and microRNA-138-5p (miR-138-5p). The effects of suppressed lncRNA SNHG12 and increased miR-138-5p levels on mRNA were determined using quantitative real-time-PCR (qRT-PCR) in 1-methyl-4-phenylpyridinium (MPP⁺) treated SH-SY5Y cells. Increased lactate dehydrogenase (LDH) activity, apoptosis, cleaved-Caspase3/Caspase3 ratio, inflammatory response, reactive oxygen species (ROS) level, decreased cell viability, and superoxide dismutase (SOD) activity were observed in MPP⁺-stimulated SH-SY5Y cells. Transfection of the lncRNA SNHG12-plasmid reduced neuronal apoptosis, inflammation, and oxidative stress in MPP⁺-stimulated SH-SY5Y cells that were rescued by adding the miR-138-5p mimic. These results showed that lncRNA SNHG12 could affect neuronal apoptosis, inflammation, and oxidative stress in a PD cell model by regulating miR-138-5p expression. TargetScan and dual-luciferase reporter analysis suggested that miR-138-5p targeted nuclear factor I/B (NFIB). Furthermore, the expression level of NFIB was downregulated after MPP⁺ stimulation in SH-SY5Y cells. After transfecting with the miR-138-5p inhibitor, NFIB-siRNA, and co-transfecting and detecting NFIB mRNA and protein, we found that miR-138-5p negatively regulated NFIB expression. In conclusion, lncRNA SNHG12 could alleviate neuronal apoptosis, inflammation, and oxidative stress in a PD cell model by regulating the miR-138-5p/NFIB axis, providing new therapeutic targets for patients with PD.

CircDLGAP4 overexpression relieves oxygen-glucose deprivation-induced neuronal injury by elevating NEGR1 through sponging miR-503-3p

Circular RNAs (circRNAs) have been reported to play vital regulatory roles in human diseases. However, the functions of circRNAs in ischemic stroke (IS) are limited. In this study, we aimed to explore the functions and mechanisms of circRNA DLG associated protein 4 (circDLGAP4) in IS development. Oxygen-glucose deprivation (OGD)-treated HCN-2 cells were used to mimic IS environment in vitro. Quantitative real-time polymerase chain reaction (qRT-PCR) assay was used to detect the levels of circDLGAP4, microRNA-503-3p (miR-503-3p) and neuronal growth regulator 1 (NEGR1) mRNA. RNase R assay was conducted to analyze the stability of circDLGAP4. Cell Counting Kit-8 (CCK-8) assay and flow cytometry analysis were adopted for cell viability and death, respectively. Western blot assay was performed for protein levels. Enzyme-linked immunosorbent assay (ELISA) kits were used to examine the concentrations of inflammatory cytokines. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull-down assay were employed to analyze the relationships among circDLGAP4, miR-503-3p and NEGR1. CircDLGAP4 level was declined in HCN-2 cells after OGD treatment. CircDLGAP4 overexpression promoted cell viability and suppressed cell death and inflammatory cytokine concentrations in OGD-treated HCN-2 cells. CircDLGAP4 acted as the sponge for miR-503-3p and the impacts of circDLGAP4 overexpression on cell viability, death and inflammation in OGD-treated HCN-2 cells were reversed by miR-503-3p elevation. Furthermore, NEGR1 was the target gene of miR-503-3p. MiR-503-3p inhibition ameliorated OGD-induced HCN-2 cell impairments, but NEGR1 knockdown abolished the effects. CircDLGAP4 alleviated OGD-induced HCN-2 cell damage by regulating miR-503-3p/NEGR1 axis.

Long non-coding RNA Gm11974 aggravates oxygen-glucose deprivation-induced injury via miR-122-5p/SEMA3A axis in ischaemic stroke

Long non-coding RNAs (lncRNAs) play important roles in ischaemic stroke. This study aimed to investigate the role and potential mechanism of lncRNA Gm11974 in ischaemic stroke. Mouse neuroblastoma N2a cells were treated with oxygen-glucose deprivation (OGD). The levels of Gm11974, microRNA-122-5p (miR-122-5p) and semaphorin 3A (SEMA3A) were detected by quantitative real-time PCR (qRT-PCR) or western blot. Cell viability and apoptosis were determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, Caspase-3 Assay Kit and flow Cytometry. The levels of oxidative stress indicators were measured by using commercial kits. The relationship between miR-122-5p and Gm11974 or SEMA3A was verified by dual-luciferase reporter, RNA immunoprecipitation and RNA pull-down assays. Middle cerebral artery occlusion (MCAO) in mice was used to mimic ischaemic stroke. Gm11974 and SEMA3A were up-regulated, while miR-122-5p was down-regulated in OGD-treated N2a cells and MCAO mice. Down-regulation of Gm11974 ameliorated OGD-mediated N2a cell damage by increasing cell viability and reducing cell apoptosis and oxidative stress. Gm11974 promoted OGD-induced injury in N2a cells via negatively regulating miR-122-5p. Also, miR-122-5p alleviated OGD-resulted N2a cell injury by targeting SEMA3A. Moreover, silencing of Gm11974 decreased infarct volume and neurological score in MCAO mice. Knockdown of Gm11974 attenuated neuronal injury in ischaemic stroke by regulating miR-122-5p/SEMA3A signaling pathway.

The Regulatory Functions of lncRNAs on Angiogenesis Following Ischemic Stroke

Ischemic stroke is one of the leading causes of global mortality and disability. It is a multi-factorial disease involving multiple factors, and gene dysregulation is considered as the major molecular mechanisms underlying disease progression. Angiogenesis can promote collateral circulation, which helps the restoration of blood supply in the ischemic area and reduces ischemic necrosis following ischemic injury. Aberrant expression of long non-coding RNAs (lncRNAs) in ischemic stroke is associated with various biological functions of endothelial cells and serves essential roles on the angiogenesis of ischemic stroke. The key roles of lncRNAs on angiogenesis suggest their potential as novel therapeutic targets for future diagnosis and treatment. This review elucidates the detailed regulatory functions of lncRNAs on angiogenesis following ischemic stroke through numerous mechanisms, such as interaction with target microRNAs, downstream signaling pathways and target molecules.