Circular RNA TLK1 Aggravates Neuronal Injury and Neurological Deficits after Ischemic Stroke via miR-335-3p/TIPARP

Non-coding RNAs in acute ischemic stroke: from brain to periphery

Acute ischemic stroke is a clinical emergency and a condition with high morbidity, mortality, and disability. Accurate predictive, diagnostic, and prognostic biomarkers and effective therapeutic targets for acute ischemic stroke remain undetermined. With innovations in high-throughput gene sequencing analysis, many aberrantly expressed non-coding RNAs (ncRNAs) in the brain and peripheral blood after acute ischemic stroke have been found in clinical samples and experimental models. Differentially expressed ncRNAs in the post-stroke brain were demonstrated to play vital roles in pathological processes, leading to neuroprotection or deterioration, thus ncRNAs can serve as therapeutic targets in acute ischemic stroke. Moreover, distinctly expressed ncRNAs in the peripheral blood can be used as biomarkers for acute ischemic stroke prediction, diagnosis, and prognosis. In particular, ncRNAs in peripheral immune cells were recently shown to be involved in the peripheral and brain immune response after acute ischemic stroke. In this review, we consolidate the latest progress of research into the roles of ncRNAs (microRNAs, long ncRNAs, and circular RNAs) in the pathological processes of acute ischemic stroke-induced brain damage, as well as the potential of these ncRNAs to act as biomarkers for acute ischemic stroke prediction, diagnosis, and prognosis. Findings from this review will provide novel ideas for the clinical application of ncRNAs in acute ischemic stroke.

Circulating miRNAs modulating systemic low-grade inflammation and affecting neurodegeneration

OBJECTIVE AND DESIGN

Inflammatory processes are an important part of the etiology of many chronic diseases across various medical domains, including neurodegeneration. Understanding their regulation on the molecular level represents a major challenge. Regulatory microRNAs (miRNAs), have been recognized for their role in post-transcriptionally modulating immune-related pathways serving as biomarkers for numerous diseases.

SUBJECTS AND METHODS

This study aims to investigate the association between 176 plasma-circulating miRNAs and the blood-based immune markers C-reactive protein and fibrinogen within the general population-based SHIP-TREND-0 cohort (N = 801) and assess their impact on neurodegeneration in linear regression and moderation analyses.

RESULTS

We provide strong evidence for miRNA-mediated regulation, particularly in relation to fibrinogen, identifying 48 significant miRNAs with a pronounced over-representation in chronic inflammatory and neurological diseases. Additional moderation analyses explored the influence of the APOE ε4 genotype and brain white matter neurodegeneration on the association between miRNAs and inflammation. Again, significant associations were observed for fibrinogen with special emphasize on hsa-miR-148a-3p, known to impact on neuroinflammation.

CONCLUSIONS

Our study suggests the involvement of several plasma-circulating miRNAs in regulating immunological markers while also being linked to neurodegeneration. The strong interplay between miRNAs and inflammation holds promising potential for clinical application in many immune-related neurodegenerative diseases.

White matter hyperintensity genetic risk factor TRIM47 regulates autophagy in brain endothelial cells

White matter hyperintensity (WMH) is strongly correlated with age-related dementia and hypertension, but its pathogenesis remains obscure. Genome-wide association studies identified TRIM47 at the 17q25 locus as a top genetic risk factor for WMH formation. TRIM family is a class of E3 ubiquitin ligase with pivotal functions in autophagy, which is critical for brain endothelial cell (ECs) remodeling during hypertension. We hypothesize that TRIM47 regulates autophagy and its loss-of-function disturbs cerebrovasculature. Based on transcriptomics and immunohistochemistry, TRIM47 is found highly expressed by brain ECs in human and mouse, and its transcription is upregulated by artificially induced autophagy while downregulated in hypertension-like conditions. Using in silico simulation, immunocytochemistry and super-resolution microscopy, we predicted a highly conserved binding site between TRIM47 and the LIR (LC3-interacting region) motif of LC3B. Importantly, pharmacological autophagy induction increased Trim47 expression on mouse ECs (b.End3) culture, while silencing Trim47 significantly increased autophagy with ULK1 phosphorylation induction, transcription, and vacuole formation. Together, we demonstrate that TRIM47 is an endogenous inhibitor of autophagy in brain ECs, and such TRIM47-mediated regulation connects genetic and physiological risk factors for WMH formation but warrants further investigation.

Blockage of p38MAPK in astrocytes alleviates brain damage in a mouse model of embolic stroke through the CX43/AQP4 axis

BACKGROUND

Cerebral edema, a significant complication arising from acute ischemic stroke (IS), has a critical influence on morbidity and mortality. p38MAPK has been shown to promote neuronal apoptosis and brain damage. However, the role of the p38MAPK inhibitor SKF-86002 in protecting against ischemic injury and cerebral edema remains unclear.

METHODS

Infarct area was examined by TTC staining in middle cerebral artery occlusion (MCAO) mice. Neurological score and brain water content were evaluated. TUNEL and NeuN staining were used to assess neuronal apoptosis and the survival of neurons. Blood-brain barrier (BBB) permeability was determined by Evans blue. Double immunofluorescence staining detected the colocalization of AQP4 and CX43 in astrocytes. IHC staining revealed CX43 and AQP4 expression. EDU staining detected the proliferation of Oxygen and glucose deprivation/reoxygenation (OGD/R)-treated astrocytes. Levels of oxidative stress markers were determined using commercial kits. ELISA was used to assess the secretion of pro-inflammatory factors. RT-qPCR measured the expression of CX43, AQP4 and pro-inflammatory factors. Western blot analyzed the levels of p-p38/p38, AQP4 and CX43. Co-immunoprecipitation (Co-IP) determined the interaction between CX43 and AQP4.

RESULTS

SKF-86002 attenuated brain damage, edema, and neuronal apoptosis in MCAO mice. Astrocyte proliferation was suppressed, and oxidative stress and inflammation were alleviated by SKF-86002 treatment. SKF-86002 negatively regulated p38 signaling and the expression of AQP4 and CX43. Additionally, the expression of CX43/AQP4 within astrocytes was modulated by SKF-86002.

CONCLUSION

In summary, SKF-86002 alleviated IS injury and cerebral edema by inhibiting astrocyte proliferation, oxidative stress and inflammation. This effect was associated with the suppression of CX43/AQP4, suggesting that SKF-86002 shows promise as a novel therapeutic approach for preventing IS.

Hsa_circ_0005548 knockdown repairs OGD/R-induced damage in human brain microvascular endothelial cells via miR-362-3p/ETS1 axis

BACKGROUND

Ischemic stroke (IS) is a highly prevalent type of stroke with very high rates of disability and death. As the regulatory role of circular RNAs (circRNAs) in various diseases has been revealed, we constructed a stroke cell model to analyze the action mechanism of hsa_circ_0005548 in IS.

METHODS

The abundance of hsa_circ_0005548, microRNA-362-3p (miR-362-3p) and E26 transformation specific-1 (ETS-1) were measured by real-time quantitative polymerase chain reaction (RT-qPCR) or western blot. We constructed an IS cell model in vitro by oxygen-glucose deprivation/reperfusion (OGD/R) treatment and analyzed cell proliferation, apoptosis and inflammatory response through the use of Cell Counting Kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry and Enzyme-linked immunosorbent assay (ELISA), respectively. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were employed for the analysis of the relationship between miR-362-3p and hsa_circ_0005548 or ETS1.

RESULTS

The higher abundance of hsa_circ_0005548 and ETS-1 and lower level of miR-362-3p were observed in human brain microvascular endothelial immortalized (HBMEC-IM) cells under OGD/R. Hsa_circ_0005548 downregulation mitigated OGD/R-induced HBMEC-IM cell injury. Mechanistically, hsa_circ_0005548 targeted miR-362-3p. MiR-362-3p knockdown reversed the effect of hsa_circ_0005548 silencing on OGD/R-induced HBMEC-IM cell injury. ETS1 was validated as a direct target of miR-362-3p, and miR-362-3p attenuated OGD/R-induced HBMEC-IM cell injury by ETS1. Moreover, hsa_circ_0005548 modulated ETS1 via miR-362-3p.

CONCLUSION

Hsa_circ_0005548 knockdown repairs OGD/R-induced HBMEC-IM cell damage via miR-362-3p/ETS1 axis.

CircRNA_0003307 promoted brain microvascular endothelial cell angiogenesis, invasion, and migration in cerebral ischemia-reperfusion injury: Potential involvement of miRNA-191-5p/CDK6 pathway

BACKGROUNDS

The role of miR-191-5p in cerebral ischemia-reperfusion (I/R) injury has been established, with its expression in endothelial cells demonstrating anti-angiogenic effects. A potential circular RNA, circRNA_0003307, has been identified through bioinformatics analysis as a candidate for interaction with miR-191-5p, yet its functional significance in brain I/R injury remains unexplored. We aimed to investigate whether circRNA_0003307 regulates brain microvascular endothelial cell (BMEC) vascular tube formation, invasion, and migration by regulating the miR-191-5p cascade.

METHODS

Mouse BMECs (bEnd.3) were culturedand exposed to oxygen-glucose deprivation (OGD). The effects of circRNA_0003307 on vessel-like tube formation and cellular migration were examined. In addition, we investigated the protective effects of circRNA_0003307 on I/R injury in mice.

RESULTS

The results showed the level of circRNA_0003307 was concentration-dependently increased in OGD-induced bEnd.3 cells. ODG-induction enhanced angiogenesis, migration, and invasion of bEnd.3 cells, which were further promoted by the transfection of pcDNA-0003307. Silencing circRNA_0003307 expression showed the opposite results. The dual luciferase assay demonstrated miRNA-191-5p interacted with circRNA_00033073' UTR, and miRNA-191-5p could bind with CDK6. Meanwhile, circRNA_0003307 promoted the expression of CDK6 by sponging miRNA-191-5p. The overexpression of circRNA_0003307 activated the angiogenesis, migration, and invasion of OGD-induced bEnd.3 cells, which were hindered by miRNA-191-5p mimic or siRNA-CDK6. Thus, circRNA_0003307 promoted ODG-induced angiogenesis, migration, and invasion of bEnd.3 cells by targeting miR-191-5p/CDK6 axis. In vivo, circRNA_0003307 had protective effects on brain I/R injury, including neuroprotection, anti-apoptosis and angiogenesis.

CONCLUSION

CircRNA_0003307 may be a promisingtherapeutictarget forthe treatment of cerebral I/R injury.

CircRNA: A new target for ischemic stroke

Ischemic stroke, a clinical emergency and disease with a poor prognosis, has a negative impact on the survival index of patients. It is frequently precipitated by a multitude of risk factors, including trauma. Currently, there is a paucity of predictive indicators for early intervention. As stable and abundant RNA in the body, circRNAs play a regulatory role in miRNAs and proteins, which affect the occurrence and development of diseases. Moreover, circRNAs can serve as predictors of clinical diseases. Several studies have demonstrated that circRNAs play pivotal roles in numerous aspects of ischemic stroke. Consequently, circRNAs have emerged as key areas of investigation in the field of ischemic stroke.

Lipidomic analysis identifies long-chain acylcarnitine as a target for ischemic stroke

INTRODUCTION

Lipid metabolism dysfunction is widely involved in the pathological process of acute ischemic stroke (AIS). The coordination of lipid metabolism between neurons and astrocytes is of great significance. However, the full scope of lipid dynamic changes and the function of key lipids during AIS remain unknown. Hence, identifying lipid alterations and characterizing their key roles in AIS is of great importance.

METHODS

Untargeted and targeted lipidomic analyses were applied to profile lipid changes in the ischemic penumbra and peripheral blood of transient middle cerebral artery occlusion (tMCAO) mice as well as the peripheral blood of AIS patients. Infarct volume and neurological deficits were assessed after tMCAO. The cell viability and dendritic complexity of primary neurons were evaluated by CCK8 assay and Sholl analysis. Seahorse, MitoTracker Green, tetramethyl rhodamine methyl ester (TMRM), 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and MitoSOX were used as markers of mitochondrial health. Fluorescent and isotopic free fatty acid (FFA) pulse-chase assays were used to track FFA flux in astrocytes.

RESULTS

Long-chain acylcarnitines (LCACs) were the lipids with the most dramatic changes in the ischemic penumbra and peripheral blood of tMCAO mice. LCACs were significantly elevated on admission in AIS patients and associated with poor outcomes in AIS patients. Increasing LCACs through a bolus administration of palmitoylcarnitine amplified stroke injury, while decreasing LCACs by overexpressing carnitine palmitoyltransferase 2 (CPT2) ameliorated stroke injury. Palmitoylcarnitine aggravated astrocytic mitochondrial damage after OGD/R, while CPT2 overexpression in astrocytes ameliorated cocultured neuron viability. Further study revealed that astrocytes stimulated by OGD/R liberated FFAs from lipid droplets into mitochondria to form LCACs, resulting in mitochondrial damage and lowered astrocytic metabolic support and thereby aggravated neuronal damage.

CONCLUSION

LCACs could accumulate and damage neurons by inducing astrocytic mitochondrial dysfunction in AIS. LCACs play a crucial role in the pathology of AIS and are novel promising diagnostic and prognostic biomarkers for AIS.

Circular RNA circEfnb2 promotes cell injury after cerebral infarction by sponging miR-202-5p and regulating TRAF3 expression

BACKGROUND

Exogenous neural cell transplantation may be therapeutic for stroke, cerebral ischemic injury. Among other mechanisms, increasing findings indicated circular RNAs (circRNAs) regulate the pathogenesis progression of cerebral ischemia. Mmu_circ_0015034 (circEfnb2) was upregulated in focal cortical infarction established by middle cerebral artery occlusion (MCAO) in mice. Our study was designed to probe the molecular mechanism of circEfnb2 in the oxygen-glucose deprivation/reperfusion (OGD/R)-induced neuronal damage in cerebral ischemia.

METHODS

We established an in vitro OGD/R cell model. CircEfnb2 and microRNA-202-5p (miR-202-5p) levels were detected using real-time quantitative polymerase chain reaction (RT-qPCR). Lactate dehydrogenase (LDH), malondialdehyde (MDA), and reactive oxygen species (ROS) levels were assessed using specific kits. Tumor necrosis factor-α (TNF-α) and Interleukin-1β (IL-1β) levels were examined using an Enzyme-linked immunosorbent assay (ELISA). Flow cytometry analysis evaluated cell apoptosis. Protein levels of B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), cleaved caspase 3, and Tumor necrosis factor receptor-associated factor 3 (TRAF3) were determined using Western blot assay.

RESULTS

Overall, circEfnb2 was highly expressed whereas miR-202-5p was decreased in OGD/R-treated mouse hippocampal neuronal HT22 cells compared to normal controls (both p > 0.05). From an in vitro functional perspective, circEfnb2 knockdown attenuated an OGD/R-triggered neuronal injury compared to controls (p > 0.05). Mechanically, circEfnb2 acted as a sponge of miR-202-5p; downregulation of miR-202-5p annulled the inhibitory roles of circEfnb2 silencing in an OGD/R-caused neuronal injury model. Our analysis showed that miR-202-5p directly targeted TRAF3 as enhanced TRAF3 abolished the effects of miR-202-5p in the OGD/R-induced neuronal injury. In vivo, lentivirus with a short hairpin (sh)-circEfnb2 inhibited cerebral injury, when injected into cerebral cortex in MCAO mice (p > 0.05).

CONCLUSION

Our results suggest that circEfnb2 deficiency may decrease OGD/R-induced HT22 cell damage by modulating the miR-202-5p/TRAF3 axis. This explanation may provide a new direction for cerebral infarction potential therapeutic targets.

Inhibition of circ_0073932 attenuates myocardial ischemia‒reperfusion injury via miR-493-3p/FAF1/JNK

Oxidative stress and apoptosis play crucial roles in myocardial ischemia‒reperfusion injury (MIRI). In this study, we investigated the role of circ_0073932 in MIRI as well as its molecular mechanism. A hypoxia/reoxygenation (H/R) cardiomyocyte model was established with H9C2 cardiomyocytes, and RT-qPCR was used to measure gene expression. We observed that circ_0073932 expression was abnormally increased in the H/R cardiomyocyte model and in blood samples from MIRI patients. Inhibition of circ_0073932 suppressed H/R-induced cell apoptosis, oxidative stress (ROS, LDH and MDA), and p-JNK expression. Dual luciferase reporter assays showed that circ_0073932 targeted the downregulation of miR-493-3p, and miR-493-3p targeted the downregulation of FAF1. Furthermore, si-circ_0073932, an miR-493-3p inhibitor, oe-FAF1, or si-FAF1 were transfected into H9C2 cardiomyocytes to investigate the roles of these factors in MIRI. Our results showed that compared with the H/R group, si-circ_0073932 inhibited H/R-induced cell apoptosis, oxidative stress (ROS, LDH and MDA), and p-JNK expression. These results were reversed by the miR-493-3p inhibitor or oe-FAF1. Finally, a rat model of MIRI was established, and si-circ_0073932 was administered. Inhibition of circ_0073932 reduced the area of myocardial infarction and decreased the levels of apoptosis and oxidative stress by inhibiting the JNK signaling pathway. Our study indicated that circ_0073932 mediates MIRI via miR-493-3p/FAF1/JNK in vivo and in vitro, revealing novel insights into the pathogenesis of MIRI and providing a new target for the clinical treatment of MIRI.

Discovery of highly potent PARP7 inhibitors for cancer immunotherapy

PARP7 has been proven to play an important role in immunity. Substantial upregulation of PARP7 is observed in numerous cancerous cell types, consequently resulting in the inhibition of type Ⅰ interferon signaling pathways. Therefore, inhibiting the activity of PARP7 can enhance type Ⅰ interferon signaling to exert an anti-tumor immune response. In this study, we reported the identification of a newly found PARP7 inhibitor (XLY-1) with higher inhibitory activity (IC50 = 0.6 nM) than that of RBN-2397 (IC50 = 6.0 nM). Additionally, XYL-1 displayed weak inhibitory activity on PARP1 (IC50 > 1.0 μM). Mechanism studies showed that XYL-1 could enhance the type Ⅰ interferon signaling in vitro. Pharmacodynamic experiments showed that 50 mg/kg XYL-1 could significantly inhibit tumor growth (TGI: 76.5 %) and related experiments showed that XYL-1 could restore type Ⅰ interferon signaling and promote T cell infiltration in tumor tissues. Taken together, XYL-1 shows promise as a potential candidate for developing cancer immunotherapy agents.

Circ_0000115 Protects Against Cerebral Ischemia Injury by Suppressing Neuronal Apoptosis, Oxidative Stress and Inflammation by miR-1224-5p/Nos3 Axis In Vitro

Cerebral ischemia is a severe neurological disability related to neuronal apoptosis and cellular stress response. Circular RNAs (circRNAs) are emerging regulators of cerebral ischemia. Herein, this study proposed to probe the action of circ_0000115 in cerebral ischemia injury. The mouse neuroblastoma cells N2a and HT22 underwent oxygen-glucose deprivation (OGD) were used as a model of in vitro cerebral ischemia. Levels of genes and proteins were detected by qRT-PCR and western blotting. Cell proliferation and apoptosis were determined by EdU assay and flow cytometry. Western blotting was used to detect the protein level of pro-inflammatory factors. The oxidative stress injury was evaluated by detecting reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) generation. Dual-luciferase reporter and RIP assays were used to confirm the target relationship between miR-1224-5p and circ_0000115 or nitric oxide synthase 3 (NOS3). OGD exposure decreased circ_0000115 and NOS3 expression, and increased miR-1224-5p in N2a and HT22 cells in a time-dependent manner. Circ_0000115 silencing attenuated OGD-induced apoptosis, oxidative stress and inflammation in N2a and HT22 cells. Mechanistically, circ_0000115 directly sponged miR-1224-5p, which targeted NOS3. Furthermore, rescue experiments showed that miR-1224-5p overexpression abolished the neuroprotective effect of circ_0000115 in N2a and HT22 cells under OGD treatment. Besides that, silencing of miR-1224-5p protected N2a and HT22 cells against OGD-evoked injury, which was counteracted by NOS3 knockdown. Circ_0000115 protects N2a and HT22 cells against OGD-evoked neuronal apoptosis, inflammation, and oxidative stress via the miR-1224-5p/NOS3 axis, providing an exciting view of the pathogenesis of cerebral ischemia.

Hippocampal circAnk3 Deficiency Causes Anxiety-like Behaviors and Social Deficits by Regulating the miR-7080-3p/IQGAP1 Pathway in Mice

BACKGROUND

Circular RNAs are highly enriched in the synapses of the mammalian brain and play important roles in neurological function by acting as molecular sponges of microRNAs. circAnk3 is derived from the 11th intron of the ankyrin-3 gene, Ank3, a strong genetic risk factor for neuropsychiatric disorders; however, the function of circAnk3 remains elusive. In this study, we investigated the function of circAnk3 and its downstream regulatory network for target genes in the hippocampus of mice.

METHODS

The DNA sequence from which circAnk3 is generated was modified using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/Cas9) technology, and neurobehavioral tests (anxiety and depression-like behaviors, social behaviors) were performed in circAnk3+/- mice. A series of molecular and biochemical assays were used to investigate the function of circAnk3 as a microRNA sponge and its downstream regulatory network for target genes.

RESULTS

circAnk3+/- mice exhibited both anxiety-like behaviors and social deficits. circAnk3 was predominantly located in the cytoplasm of neuronal cells and functioned as a miR-7080-3p sponge to regulate the expression of Iqgap1. Inhibition of miR-7080-3p or restoration of Iqgap1 in the hippocampus ameliorated the behavioral deficits of circAnk3+/- mice. Furthermore, circAnk3 deficiency decreased the expression of the NMDA receptor subunit GluN2a and impaired the structural plasticity of dendritic synapses in the hippocampus.

CONCLUSIONS

Our results reveal an important role of the circAnk3/miR-7080-3p/IQGAP1 axis in maintaining the structural plasticity of hippocampal synapses. circAnk3 might offer new insights into the involvement of circular RNAs in neuropsychiatric disorders.

The Mechanisms of Long Non-coding RNA-XIST in Ischemic Stroke: Insights into Functional Roles and Therapeutic Potential

Ischemic stroke, which occurs due to the occlusion of cerebral arteries, is a common type of stroke. Recent research has highlighted the important role of long non-coding RNAs (lncRNAs) in the development of cerebrovascular diseases, specifically ischemic stroke. Understanding the functional roles of lncRNAs in ischemic stroke is crucial, given their potential contribution to the disease pathology. One noteworthy lncRNA is X-inactive specific transcript (XIST), which exhibits downregulation during the early stages of ischemic stroke and subsequent upregulation in later stages. XIST exert its influence on the development of ischemic stroke through interactions with multiple miRNAs and transcription factors. These interactions play a significant role in the pathogenesis of the condition. In this review, we have provided a comprehensive summary of the functional roles of XIST in ischemic stroke. By investigating the involvement of XIST in the disease process, we aim to enhance our understanding of the mechanisms underlying ischemic stroke and potentially identify novel therapeutic targets.

Penumbra-targeted CircOGDH siRNA-loaded nanoparticles alleviate neuronal apoptosis in focal brain ischaemia

BACKGROUND

Nanoparticles (NPs) are a class of substances that can be loaded with therapeutic agents delivered to specific areas. In our earlier research, we identified a neuron-derived circular RNA (circRNA), circular oxoglutarate dehydrogenase (CircOGDH), as a promising therapeutic target for acute ischaemic stroke. This study dedicated to explore a prospective preliminary strategy of CircOGDH-based NP delivered to the ischaemic penumbra region in middle cerebral artery occlusion/reperfusion (MCAO/R) mice.

METHODS

Immunofluorescence in primary cortex neurons and in vivo fluorescence imaging revealed endocytosis of Poly(lactide-co-glycolide) (PLGA) poly amidoamine(PAMAM)@CircOGDH small interfering RNA (siRNA) NPs. Western blotting analysis and CCK8 assay were performed to evaluate the apoptotic level in ischaemic neurons treated with PLGA-PAMAM@CircOGDH siRNA NPs. Quantitative reverse transcription PCR experiments, mice behaviour test, T2 MRI analysis, Nissl and TdT-mediated dUTP nick end labeling (TUNEL) co-staining were performed to evaluate the apoptosis level of ischaemic penumbra neurons in MCAO/R mice. Biosafety evaluation of NPs in MCAO/R mice was detected by blood routine examination, liver and kidney function examination and HE staining.

RESULTS

PLGA-PAMAM@CircOGDH siRNA NPs were successfully assembled. Endocytosis of PLGA-PAMAM@CircOGDH siRNA NPs in ischaemic neurons alleviated neuronal apoptotic level in vitro and in vivo. Furthermore, mice behaviour test showed that the neurological defects of MCAO/R mice were significantly alleviated after the tail injection of PLGA-PAMAM@CircOGDH siRNA NPs, and no toxic effects were observed.

CONCLUSION

In conclusion, our results suggest that PLGA-PAMAM@CircOGDH siRNA NPs can be delivered to the ischaemic penumbra region and alleviate neuron apoptosis in MCAO/R mice and in ischaemic neurons; therefore, our study provides a desirable approach for using circRNA-based NPs for the treatment of ischaemic stroke.

CircRNA_102046 Affects the Occurrence and Development of Ischemic Stroke by Regulating the miR-493-5p/ROCK1 Signaling

In our previous studies, the results have revealed that circRNA_102046 is significantly upregulated in plasma of patients with ischemic stroke, which closely related to NIHSS score. Human neural stem cells (hNSCs) were used for characterization and subcellular localization of circRNA_102046, and hNSCs OGD/R model was generated. The proliferation of cells was examined by CCK-8 assay. The expression levels of associated molecules were evaluated using RT-qPCR, immunofluorescence staining or western blotting. The binding and co-localization of associated molecules were also evaluated by RIP and FISH assay. Furthermore, MCAO mouse model was established to examine the effects of circRNA_102046 on the progression of ischemic stroke. Expression of circRNA_102046 was detected in the cytoplasma of hNSCs. Then OGD/R cell model was established, where the levels of circRNA_102046 was significantly up-regulated. Furthermore, knockdown of circRNA_102046 was able to enhance the proliferation and differentiation of OGD/R hNSCs. In further downstream molecular studies, the results indicated that circRNA_102046 could participate in the occurrence and development of ischemic stroke through targeting miR-493-5p. In addition, ROCK1 was identified as the putative target of miR-493-5p, and circRNA_102046 regulates the proliferation and differentiation of hNSCs via the miR-493-5p/ROCK1 signaling. More importantly, the infarct volumes of MCAO mice were remarkably reduced after the treatment with sh-circRNA_102046, which also up- and down-regulate the expression of miR-493-5p and ROCK1, respectively. Elucidating this novel pathway provides a theoretical basis for the development of new diagnostic approach and targeted treatment for ischemic stroke.

LMGATCDA: Graph Neural Network With Labeling Trick for Predicting circRNA-Disease Associations

Previous studies have proven that circular RNAs (circRNAs) are inextricably connected to the etiology and pathophysiology of complicated diseases. Since conventional biological research are frequently small-scale, expensive, and time-consuming, it is essential to establish an efficient and reasonable computation-based method to identify disease-related circRNAs. In this article, we proposed a novel ensemble model for predicting probable circRNA-disease associations based on multi-source similarity information(LMGATCDA). In particular, LMGATCDA first incorporates information on circRNA functional similarity, disease semantic similarity, and the Gaussian interaction profile (GIP) kernel similarity as explicit features, along with node-labeling of the three-hop subgraphs extracted from each linked target node as graph structural features. After that, the fused features are used as input, and further implied features are extracted by graph sampling aggregation (GraphSAGE) and multi-hop attention graph neural network (MAGNA). Finally, the prediction scores are obtained through a fully connected layer. With five-fold cross-validation, LMGATCDA demonstrated excellent competitiveness against gold standard data, reaching 95.37% accuracy and 91.31% recall with an AUC of 94.25% on the circR2Disease benchmark dataset. Collectively, the noteworthy findings from these case studies support our conclusion that the LMGATCDA model can provide reliable circRNA-disease associations for clinical research while helping to mitigate experimental uncertainties in wet-lab investigations.

CircRNA and Stroke: New Insight of Potential Biomarkers and Therapeutic Targets

Stroke, the second-largest cause of death and the leading cause of disability globally, presents significant challenges in terms of prognosis and treatment. Identifying reliable prognosis biomarkers and treatment targets is crucial to address these challenges. Circular RNA (circRNA) has emerged as a promising research biomarkers and therapeutic targets because of its tissue specificity and conservation. However, the potential role of circRNA in stroke prognosis and treatment remains largely unexplored. This review briefly elucidate the mechanism underlying circRNA's involvement in stroke pathophysiology. Additionally, this review summarizes the impact of circRNA on different forms of strokes, including ischemic stroke and hemorrhagic stroke. And, this article discusses the positive effects of circRNA on promoting cerebrovascular repair and regeneration, maintaining the integrity of the blood-brain barrier (BBB), and reducing neuronal injury and immune inflammatory response. In conclusion, the significance of circRNA as a potential prognostic biomarker and a viable therapeutic target was underscored.

METTL3 Mediates Microglial Activation and Blood-Brain Barrier Permeability in Cerebral Ischemic Stroke by Regulating NLRP3 Inflammasomes Through m6A Methylation Modification

Cerebral ischemic stroke (CIS) is the main cause of disability. METTL3 is implicated in CIS, and we explored its specific mechanism. Middle cerebral artery occlusion (MCAO) rat model and oxygen-glucose deprivation/reperfusion (OGD/R) HAPI cell model were established and treated with LV-METTL3 or DAA, oe-METTL3, miR-335-3p mimics, or DAA, to assess their effects on MCAO rat neurological and motor function, cerebral infarction area, brain water content, microglial activation, blood-brain barrier (BBB) permeability, and NLRP3 inflammasome activation. METTL3, pri-miR-335-3p, mature miR-335-3p, and miR-335-3p mRNA levels were assessed by RT-qPCR; M1/M2 microglial phenotype proportion and M1/M2 microglia ratio, inflammatory factor levels, and m6A modification were assessed. MCAO rats manifested cerebral ischemia injury. METTL3 was under-expressed in CIS. METTL3 overexpression inhibited microglial activation and M1 polarization and BBB permeability in MCAO rats and inhibited OGD/R-induced microglial activation and reduced M1 polarization. METTL3 regulated miR-335-3p expression and inhibited NLRP3 inflammasome activation. m6A methylation inhibition averted METTL3's effects on NLRP3 activation, thus promoting microglial activation in OGD/R-induced cells and METTL3's effects on BBB permeability in MCAO rats. Briefly, METTL3 regulated miR-335-3p expression through RNA m6A methylation and inhibited NLRP3 inflammasome activation, thus repressing microglial activation, BBB permeability, and protecting against CIS.

Discovery of Highly Selective PARP7 Inhibitors with a Novel Scaffold for Cancer Immunotherapy

PARP7 plays a crucial role in cancer immunity. The inhibition of PARP7 has shown potential in boosting the immune response against cancer, making it an attractive target for cancer immunotherapy. Herein, we employed a rigid constraint strategy (reduction in molecular flexibility) to design and synthesize a series of novel indazole-7-carboxamide derivatives based on the structure of RBN-2397. Among these derivatives, (S)-XY-05 was identified as the most promising PARP7 inhibitor (IC50: 4.5 nM). Additionally, (S)-XY-05 showed enhanced selectivity toward PARP7 and improved pharmacokinetic properties (oral bioavailability: 94.60%) compared with RBN-2397 (oral bioavailability: 25.67%). In the CT26 syngeneic mouse model, monotherapy with (S)-XY-05 displayed a strong antitumor effect (TGI: 83%) by activating T-cell-mediated immunity within the tumor microenvironment. Collectively, we confirmed that (S)-XY-05 has profound effects on tumor immunity, which paves the way for future studies of PARP7 inhibitors that could be utilized in cancer immunotherapy.

Integrating spatial and single-cell transcriptomics to characterize the molecular and cellular architecture of the ischemic mouse brain

Neuroinflammation is acknowledged as a pivotal pathological event after cerebral ischemia. However, there is limited knowledge of the molecular and spatial characteristics of nonneuronal cells, as well as of the interactions between cell types in the ischemic brain. Here, we used spatial transcriptomics to study the ischemic hemisphere in mice after stroke and sequenced the transcriptomes of 19,777 spots, allowing us to both visualize the transcriptional landscape within the tissue and identify gene expression profiles linked to specific histologic entities. Cell types identified by single-cell RNA sequencing confirmed and enriched the spatial annotation of ischemia-associated gene expression in the peri-infarct area of the ischemic hemisphere. Analysis of ligand-receptor interactions in cell communication revealed galectin-9 to cell-surface glycoprotein CD44 (LGALS9-CD44) as a critical signaling pathway after ischemic injury and identified microglia and macrophages as the main source of galectins after stroke. Extracellular vesicle-mediated Lgals9 delivery improved the long-term functional recovery in photothrombotic stroke mice. Knockdown of Cd44 partially reversed these therapeutic effects, inhibiting oligodendrocyte differentiation and remyelination. In summary, our study provides a detailed molecular and cellular characterization of the peri-infact area in a murine stroke model and revealed Lgals9 as potential treatment target that warrants further investigation.

A therapeutical insight into the correlation between circRNAs and signaling pathways involved in cancer pathogenesis

Pre-messenger RNA molecules are back-spliced to create circular RNAs, which are non-coding RNA molecules. After a thorough investigation, it was discovered that these circRNAs have critical biological roles. CircRNAs have a variety of biological functions, including their ability to operate as microRNA sponges, interact with proteins to alter their stabilities and activities, and provide templates for the translation of proteins. Evidence supports a link between the emergence of numerous diseases, including various cancer types, and dysregulated circRNA expression. It is commonly known that a significant contributing element to cancer development is the disruption of numerous molecular pathways essential for preserving cellular and tissue homeostasis. The dysregulation of multiple biological processes is one of the hallmarks of cancer, and the molecular pathways linked to these processes are thought to be promising targets for therapeutic intervention. The biological and carcinogenic effects of circRNAs in the context of cancer are thoroughly reviewed in this article. Specifically, we highlight circRNAs' involvement in signal transduction pathways and their possible use as novel biomarkers for the early identification and prognosis of human cancer.

Knockdown of Smox protects the integrity of the blood-brain barrier through antioxidant effect and Nrf2 pathway activation in stroke

Once an ischemic stroke occurs, reactive oxygen species (ROS) and oxidative stress degrade the tight connections between cerebral endothelial cells resulting in their damage. The expression of antioxidant genes may be enhanced, and ROS formation may be reduced following Nrf2 activation, which is associated with protection against ischemic stroke. Overexpression of spermine oxidase (Smox) in the neocortex led to increased H2O2 production. However, how Smox impacts the regulation of the blood-brain barrier (BBB) through antioxidants has not been examined yet. We conducted experiments both in the cell level and in the transient middle cerebral artery occlusion (tMCAO) model to evaluate the effect of Smox siRNA lentivirus (si-Smox) knockdown on BBB protection against ischemic stroke. Mice treated with si-Smox showed remarkably decreased BBB breakdown and reduced endothelial inflammation following stroke. The treatment with si-Smox significantly elevated the Bcl-2 to Bax ratio and decreased the production of cleaved caspase-3 in the tMCAO model. Further investigation revealed that the neuroprotective effect was the result of the antioxidant properties of si-Smox, which reduced oxidative stress and enhanced CD31+ cells in the peri-infarct cortical areas. Of significance, si-Smox activated Nrf2 in both bEnd.3 cells and tMCAO animals, and blocking Nrf2 with brusatol diminished the protective effects of si-Smox. The study findings suggest that si-Smox exerts neuroprotective effects and promotes angiogenesis by activating the Nrf2 pathway, thus decreasing oxidative stress and apoptosis caused by tMCAO. As a result, si-Smox may hold potential as a therapeutic candidate for preserving BBB integrity while treating ischemic stroke.

White matter hyperintensity genetic risk factor TRIM47 regulates autophagy in brain endothelial cells

White matter hyperintensity (WMH) is strongly correlated with age-related dementia and hypertension, but its pathogenesis remains obscure. GWAS identified TRIM47 at 17q25 locus as a top genetic risk factor for WMH formation. TRIM family is a class of E3 ubiquitin ligase with pivotal functions in autophagy, which is critical for brain endothelial cell (ECs) remodeling during hypertension. We hypothesize that TRIM47 regulates autophagy and its loss-of-function disturbs cerebrovasculature. Based on transcriptomics and immunohistochemistry, TRIM47 is found selectively expressed by brain ECs in human and mouse, and its transcription is upregulated by artificially-induced autophagy while downregulated in hypertension-like conditions. Using in silico simulation, immunocytochemistry and super-resolution microscopy, we identified the highly conserved binding site between TRIM47 and the LIR (LC3-interacting region) motif of LC3B. Importantly, pharmacological autophagy induction increased Trim47 expression on mouse ECs (b.End3) culture, while silencing Trim47 significantly increased autophagy with ULK1 phosphorylation induction, transcription and vacuole formation. Together, we confirm that TRIM47 is an endogenous inhibitor of autophagy in brain ECs, and such TRIM47-mediated regulation connects genetic and physiological risk factors for WMH formation but warrants further investigation.

SUMMARY STATEMENT

TRIM47, top genetic risk factor for white matter hyperintensity formation, is a negative regulator of autophagy in brain endothelial cells and implicates a novel cellular mechanism for age-related cerebrovascular changes.

Transcriptomic and bioinformatics analysis of the mechanism by which erythropoietin promotes recovery from traumatic brain injury in mice

Recent studies have found that erythropoietin promotes the recovery of neurological function after traumatic brain injury. However, the precise mechanism of action remains unclear. In this study, we induced moderate traumatic brain injury in mice by intraperitoneal injection of erythropoietin for 3 consecutive days. RNA sequencing detected a total of 4065 differentially expressed RNAs, including 1059 mRNAs, 92 microRNAs, 799 long non-coding RNAs, and 2115 circular RNAs. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses revealed that the coding and non-coding RNAs that were differentially expressed after traumatic brain injury and treatment with erythropoietin play roles in the axon guidance pathway, Wnt pathway, and MAPK pathway. Constructing competing endogenous RNA networks showed that regulatory relationship between the differentially expressed non-coding RNAs and mRNAs. Because the axon guidance pathway was repeatedly enriched, the expression of Wnt5a and Ephb6, key factors in the axonal guidance pathway, was assessed. Ephb6 expression decreased and Wnt5a expression increased after traumatic brain injury, and these effects were reversed by treatment with erythropoietin. These findings suggest that erythropoietin can promote recovery of nerve function after traumatic brain injury through the axon guidance pathway.

Identification of Key Genes Mediated by N6-Methyladenosine Methyltransferase METTL3 in Ischemic Stroke via Bioinformatics Analysis and Experiments

The N6-methyladenosine (m6A) methyltransferase METTL3 has been demonstrated to function in mediating m6A modification, but its role in ischemic stroke (IS) has not been fully elucidated. This study aimed to explore the downstream mechanism of METTL3-mediated m6A modification in IS. GSE16561 and GSE22255 were downloaded from the Gene Expression Omnibus database for analysis of differentially expressed genes (DEGs), and it was found that METTL3 mRNA was downregulated in IS. Then quantitative real-time polymerase chain reaction was used to verify the downregulation of METTL3 mRNA in the peripheral blood of IS patients and the cortexes of transient middle cerebral artery occlusion mice. By combining DEGs with the m6A-downregulated genes in GSE142386 which performed methylated RNA immunoprecipitation sequencing (MeRIP-seq) on METTL3-deficient and control endothelial cells, a total of 131 genes were identified as the METTL3-mediated m6A-modified genes in IS. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the genes were mainly involved in cytokine-cytokine receptor interaction, MAPK signaling pathway and NF-kappa B signaling pathway. CTSS and SBK1 were further screened as the key METTL3-mediated m6A-modified genes by random forest model and PCR validation. The ROC curve analysis showed that the combination with CTSS and SBK1 was of good diagnostic value for IS, with the AUC of 0.810, sensitivity of 0.780, and specificity of 0.773. Overall, we found that METTL3-mediated m6A modification may influence the occurrence and development of IS by participating in inflammation-related biological processes, and two key m6A-modified genes mediated by METTL3 (CTSS and SBK1) can be used as diagnostic biomarkers for IS.

Circular RNA DLGAP4 alleviates sevoflurane-induced neurotoxicity by regulating miR-9-5p/Sirt1/BDNF pathway

BACKGROUND

Sevoflurane is a widely used anesthetic in infants. However, long and repeated exposure to this drug can cause developmental neurotoxicity. This study aimed to investigate the role and mechanism of circular RNA DLGAP4 (circDLGAP4) in sevoflurane-induced neurotoxicity.

METHODS

Neonatal mice and mouse hippocampal neuronal cell line HT22 were used to construct sevoflurane-induced nerve injury models. The role of circDLGAP4 in sevoflurane-induced neurotoxicity was evaluated by gain-and/or loss-of-function methods. Pathological alterations in hippocampus were analyzed by hematoxylin-eosin and Tunel staining. Cell injury was assessed by cell viability and apoptosis, which was detected by CCK-8 and flow cytometry. The expression of circDLGAP4 and miR-9-5p was determined by real-time PCR. Sirt1 and BDNF levels were measured by Western blot. Productions of TNF-α and IL-6 were examined by ELISA. Dual-luciferase reporter assay and/or RNA pull-down assay were used to confirm the direct binding among circDLGAP4, miR-9-5p, and Sirt1. Rescue experiments were used to further verify the mechanism of circDLGAP4.

RESULTS

CircDLGAP4 expression was decreased by sevoflurane both in vivo and in vitro. Overexpression of circDLGAP4 elevated cell viability, reduced apoptosis and levels of TNF-α and IL-6, while circDLGAP4 knockdown showed the opposite effects in sevoflurane-induced HT22 cells. Mechanically, circDLGAP4 functioned via directly binding to and regulating miR-9-5p, followed by targeting the Sirt1/BDNF pathway. Additionally, circDLGAP4 upregulation relieved sevoflurane-induced nerve injury, reduced levels of TNF-α, IL-6 and miR-9-5p, but increased the expression of Sirt1 and BDNF in hippocampus.

CONCLUSIONS

Our studies found that circDLGAP4 relieved sevoflurane-induced neurotoxicity by sponging miR-9-5p to regulate Sirt1/BDNF pathway.

CircAFF2 Promotes Neuronal Cell Injury in Intracerebral Hemorrhage by Regulating the miR-488/CLSTN3 Axis

BACKGROUND

Intracerebral hemorrhage (ICH), a subtype of devastating stroke, carries high morbidity and mortality worldwide. CircRNA AFF2 (circAFF2) was significantly increased in ICH patients, but the underlying mechanism of circAFF2 is unknown.

METHODS

Hemin was employed to treat neuronal cells to mimic ICH in vitro. Mice were injected with collagenase VII-S to establish in vivo ICH models. Genes and protein expressions were detected using qRT-PCR and Western blotting. The interaction among circAFF2, miR-488, and CLSTN3 was validated by dual-luciferase reporter assay and RNA-RIP. Cell viability, MDA, iron, GSH, and lipid ROS were examined using the MTT, the commercial kits, and flow cytometry, respectively. ICH injury in mice was evaluated using neurological deficit scores and brain water measurements.

RESULTS

CircAFF2 was significantly increased in ICH in vivo and in vitro models. CircAFF2 bound to miR-488 and knockdown of circAFF2 or overexpression of miR-488 inhibited hemin-induced injury of neuronal cells as indicated by increased cell viability and reduced markers of oxidative stress and lipid peroxidation. CLSTN3 was the downstream target of miR-488. Silencing of circAFF2 or miR-488 overexpression reduced CLSTN3 expression and protected against the injury of neuronal cells. In vivo experiments finally confirmed that circAFF2 knockdown attenuated mice ICH injury via the miR-488/CLSTN3 axis.

CONCLUSION

CircAFF2 promotes the injury of neuronal cells and exacerbates ICH via increasing CLSTN3 by sponging miR-488, suggesting that circAFF2 may be a potential therapeutic target for ICH treatment.

circ-Gucy1a2 Protects Mice from Cerebral Ischemia-Reperfusion Injury by Attenuating Neuronal Apoptosis and Mitochondrial Membrane Potential Loss

Cerebral ischemia-reperfusion (I/R) injury (CI/RI) is a severe problem in patients with cerebral ischemia. The current study explored the influences of circular (circ)-Gucy1a2 on neuronal apoptosis and mitochondrial membrane potential (MMP) in the brain tissue of CI/RI mice. Forty-eight mice were randomized into the sham group, transient middle cerebral artery occlusion (tMCAO) group, lentivirus negative control (LV-NC) group, and LV-Gucy1a2 group. Mice were first injected with lentivirus loaded with LV-Gucy1a2 or LV-NC via lateral ventricle, followed by the establishment of CI/RI models 2 weeks later. Twenty-four hours after CI/RI, the neurological impairment of mice was assessed using a 6-point scoring system. The cerebral infarct volume and brain histopathological changes were determined in CI/RI mice through histological staining. In vitro, pcDNA3.1-NC and pcDNA3.1-Gucy1a2 were transfected into mouse primary cortical neurons for 48 hours, followed by the establishment of oxygen-glucose deprivation/reoxygenation (OGD/R) models. The levels of circ-Gucy1a2 in mouse brain tissues and neurons were examined using RT-qPCR. Neuronal proliferation and apoptosis, MMP loss, and oxidative stress (OS)-related indexes in neurons were detected using CCK-8 assay, flow cytometry, JC-1 staining, and H2DFFDA staining. CI/RI mouse models and OGD/R cell models were successfully established. After CI/RI, neurons in mice were impaired and the cerebral infarction volume was increased. circ-Gucy1a2 was poorly expressed in CI/RI mouse brain tissues. Overexpression of circ-Gucy1a2 increased OGD/R-induced neuronal proliferation and mitigated apoptosis, MMP loss, and OS. Overall, circ-Gucy1a2 was down-regulated in brain tissues of CI/RI mice, and overexpression of circ-Gucy1a2 can protect mice from CI/RI.

CircCRIM1/microRNA-141-3p/thioredoxin-binding protein axis mediates neuronal apoptosis after cerebral ischemia-reperfusion

Numerous studies have indicated enrichment of circular RNA (circRNA) in the brain takes on a momentous role in cerebral ischemia-reperfusion (CIR) injury. A recent study discovered a novel circCRIM1, was highly expressed in the middle cerebral artery occlusion-reperfusion (MCAO/R) model. Nevertheless, its specific biological function remained unknown. The study was to explore circCRIM1 in CIR-induced neuronal apoptosis. As measured, circCRIM1 and TXNIP were up-regulated, while miR-141-3p was down-regulated in MCAO/R mouse model and OGD/R SH-SY5Y cells. Depleting circCRIM1 reduced the number of apoptotic neurons in MCAO/R rats, increased the number of Nissl bodies, prevented reactive oxygen species production and oxidative stress imbalance in brain tissues, repressed cleaved caspase-3, Bax, and Cyto C protein levels and increased Bcl-2 levels. Overexpression of circCRIM1 further repressed neuronal activity and accelerated apoptosis in OGD/R model, disrupted redox balance. Depleting circCRIM1 had the opposite effect in OGD/R model. Knocking down miR-141-3p or TXNIP weakened the effects of knocking down circCRIM1 or overexpressing circCRIM1, separately. Mechanistically, circCRIM1 exerted an active role in CIR injury via miR-141-3p to mediate TXNIP. All in all, the circCRIM1/miR-141-3p/TXNIP axis might be a latent therapeutic target for CIR injury.

CircPTP4A2 Promotes Microglia Polarization in Cerebral Ischemic Stroke via miR-20b-5p/YTHDF1/TIMP2 Axis

Activated microglia play dual roles in ischemic stroke (IS) according to its polarization states. Herein, we investigated the function of circPTP4A2 in regulating microglia polarization in IS. IS models were established by MACO/R and OGD/R treatment. TTC staining was employed to detect cerebral infarct size. Cell vitality was measured using CCK-8 assay. CD16 and CD206 levels were examined using flow cytometry. The interactions between circPTP4A2, miR-20b-5p, and YTHDF1 were analyzed by dual-luciferase reporter gene, RIP, or RNA pull-down assays. circPTP4A2 was upregulated in IS patients. circPTP4A2 knockdown alleviated MCAO/R-induced cerebral injury in mice. circPTP4A2 knockdown promoted microglia M2 polarization after OGD/R. circPTP4A2 promoted YTHDF1 expression by sponging miR-20b-5p. The promoting effect of circPTP4A2 knockdown on microglia M2 polarization was abrogated by miR-20b-5p inhibition. YTHDF1 activated the NF-κB pathway by increasing TIMP2 mRNA stability and expression. circPTP4A2 downregulation promoted microglia M2 polarization to inhibit IS development by regulating the miR-20b-5p/YTHDF1/TIMP2/NF-κB axis.

CircTLK1 alleviates oxygen-glucose deprivation/reperfusion induced apoptosis in HK-2 cells through miR-136-5p/Bcl2 signal axis

The biological functions of circTLK1 in acute kidney injury (AKI), which mainly results from renal ischemia-reperfusion (IR), remain largely unknown. HK-2 cell treatment with oxygen and glucose deprivation, reoxygenation, and glucose (OGD/R) was used to simulate an AKI model that was mainly caused by renal IR. Then, the circTLK1 expression level in HK-2 cells treated with OGD/R was assessed by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Functional experiments were performed with circTLK1 knockdown of HK-2 cells via Cell Counting Kit-8 (CCK8), flow cytometry (FCM), RT-qPCR, and western blotting. The circTLK1-miRNAs-mRNAs network was constructed following the ceRNA mechanism and visualized by Cytoscape software to investigate the mechanism of circTLK1 in AKI. RT-qPCR was performed to verify the relationship between circTLK1, miR-136-5p, and Bcl2. The level of miR-136-5p was knocked down to ensure its function in OGD/R-triggered apoptosis through experiments, including CCK8, FCM, RT-qPCR, and western blotting. CircTLK1 was downregulated in HK-2 cells subjected to OGD/R treatment and in mouse kidney tissues after renal IR, but the expression of miR-136-5p was the opposite. Interference with circTLK1 expression accelerated HK-2 cell apoptosis, which was overturned by miR-136-5p inhibitors. CircTLK1 targets miR-136-5p to upregulate Bcl2 expression and attenuate apoptosis in HK-2 cells. These data revealed the possible role of circTLK1 as a new biomarker for diagnosis as well as a target in AKI through the miR-136-5p/Bcl2 signaling axis.

circ_0000018 downregulation peripherally ameliorates neuroprotection against acute ischemic stroke through the miR‑871/BCL2L11 axis

Acute ischemic stroke (AIS) is a common acute cerebrovascular disease. Circular RNAs (circRNAs) have been demonstrated to have critical functions in a wide range of physiological processes and disorders in humans. However, their precise function in ischemic stroke (IS) remains largely unknown. The present study explored the function and potential mechanisms of circ_0000018 in AIS in vivo and in vitro. The cerebral ischemia/reperfusion injury model was established in vivo and in vitro using the oxygen‑glucose deprivation (OGD/R) and transient middle cerebral artery occlusion (tMCAO) methods. Subsequently, the impact of circ_0000018 on cerebral ischemia/reperfusion injury was assessed using various techniques, including TTC staining, quantitative PCR, western blotting, cell counting kit‑8 assay, Annexin V‑FITC Apoptosis Detection Kit, luciferase reporter gene assays, and others. The levels of circ_0000018 were markedly increased in the OGD/R‑treated neuronal cells and in a mouse model of tMCAO. The blocking of microRNA (miR)‑871 by circ_0000018 promoted Bcl‑2‑like protein 11 (BCL2L11) expression to increase neuronal cell damage. Furthermore, circ_0000018 knockdown significantly improved neuronal cell viability and attenuated OGD/R‑treated neuronal cell death. Meanwhile, circ_0000018 knockdown improved brain infarct volume and neuronal apoptosis in tMCAO mice. The present study found that circ_0000018 knockdown relieved cerebral ischemia‑reperfusion injury progression in vitro and in vivo. Mechanistically, circ_0000018 regulated the levels of BCL2L11 by sponging miR‑871.

URB597 exerts neuroprotective effects against transient brain ischemia injury in mice by regulating autophagic flux and necroptosis

Ischemic stroke is a leading cause of death and disability, and medical treatments for ischemic stroke are very limited. URB597 is a potent and selective inhibitor of fatty acid amide hydrolase (FAAH). However, the effect of URB597 on ischemic stroke and the underlying molecular mechanisms remain little known. In this study, focal cerebral ischemia was induced by transient middle cerebral artery occlusion in mice. Our results showed that URB597 dose-dependently improved neurological function and reduced brain infarct volume and brain edema 24 h after brain ischemia. The most effective dose was 1 mg/kg and the therapeutic time window was within 3 h after ischemic stroke. To further investigate the underlying mechanism, necroptosis and autophagy flux were detected by Western blot and/or immunofluorescence staining with or without chloroquine, an autophagic flux inhibitor. Our results showed that URB597 promoted autophagic flux and reduced neuronal necroptosis after brain ischemia and these effects could be abolished by chloroquine. In addition, we found that peroxisome proliferator-activated receptor α (PPARα) antagonist GW6471 partly abolished the effect of URB597 against brain ischemia and URB597 upregulated the expressions of PPARα. In conclusion, URB597 exerts a neuroprotective effect in a dose- and time-dependent manner, and this effect may be related to its restoration of autophagic flux and inhibition of neuronal necroptosis. PPARα is involved in the neuroprotective effect of URB597. This study provides novel evidence that URB597 may be a promising agent for the clinical treatment of ischemic stroke.

Are Ischemic Stroke and Alzheimer's Disease Genetically Consecutive Pathologies?

Complex diseases that affect the functioning of the central nervous system pose a major problem for modern society. Among these, ischemic stroke (IS) holds a special place as one of the most common causes of disability and mortality worldwide. Furthermore, Alzheimer's disease (AD) ranks first among neurodegenerative diseases, drastically reducing brain activity and overall life quality and duration. Recent studies have shown that AD and IS share several common risk and pathogenic factors, such as an overlapping genomic architecture and molecular signature. In this review, we will summarize the genomics and RNA biology studies of IS and AD, discussing the interconnected nature of these pathologies. Additionally, we highlight specific genomic points and RNA molecules that can serve as potential tools in predicting the risks of diseases and developing effective therapies in the future.

Circular RNAs: Diagnostic and Therapeutic Perspectives in CNS Diseases

Circular RNAs (circRNAs) are a class of regulatory non-coding RNAs characterized by the presence of covalently closed ends. A growing body of evidence suggests that circRNAs play important roles in physiology and pathology. In particular, accumulating data on circRNA functions in various central nervous system (CNS) diseases and their correlations indicate that circRNAs are critical contributors to the onset and development of brain disorders. In this review, we focus on the regulatory and functional roles of circRNAs in CNS diseases, highlighting their diagnostic and therapeutic potential, with the aim of providing new insights into CNS diseases.

Depletion of circ_0006459 protects human brain microvascular endothelial cells from oxygen-glucose deprivation-induced damage through the miR-940/FOXJ2 pathway

BACKGROUND

Multiple circular RNAs (circRNAs) play important roles in ischemic stroke. The present study aims to reveal the role and the mechanism of circ_0006459 in ischemic stroke.

METHODS

Human brain microvascular endothelial cells (HBMECs) were treated with oxygen-glucose deprivation (OGD) to mimic an in vitro ischemic stroke model. RNA expression of circ_0006459, microRNA-940 (miR-940), and forkhead box J2 (FOXJ2) was detected by quantitative real-time polymerase chain reaction. Cell proliferation was analyzed by cell counting kit-8 (CCK-8) and 5-Ethynyl-29-deoxyuridine (EdU) assays. Cell apoptotic rate was quantified by flow cytometry analysis. The protein expression of proliferating cell nuclear antigen (PCNA), clusters of differentiation 6 (CDK6), BCL2-associated x protein (Bax), B-cell lymphoma 2 (Bcl2), interleukin-1β (IL-1β), IL-8, IL-18 and tumor necrosis factor-α (TNF-α) was analyzed by Western blotting. The regulatory relationships among circ_0006459, miR-940, and F 《》 OXJ2 were identified by dual-luciferase reporter assay, RNA immunoprecipitation assay, and RNA pull-down assay.

RESULTS

Circ_0006459 and FOXJ2 expression were significantly upregulated, whereas miR-940 expression was downregulated in HBMECs after OGD. Circ_0006459 depletion assuaged OGD-induced inhibition in cell proliferation and promotion in cell apoptosis and inflammation in HBMECs. Circ_0006459 acted as a sponge for miR-940, and miR-940 targeted FOXJ2 in HBMECs. Besides, miR-940 silencing or FOXJ2 overexpression relieved circ_0006459 knockdown-induced promotion in cell proliferation and inhibition in cell apoptosis and inflammation in OGD-induced HBMECs. Further, circ_0006459 depletion decreased FOXJ2 protein expression by interacting with miR-940.

CONCLUSION

Depletion of circ_0006459 protected human brain microvascular endothelial cells from oxygen-glucose deprivation-induced damage through miR-940/FOXJ2 pathway, providing a promising therapeutic target for ischemic stroke.

Importance of microRNAs by mRNA-microRNA integration analysis in acute ischemic stroke patients

OBJECTS

The roles of mRNA and microRNA (miRNA) are well known in many diseases, including ischemic stroke; thus, integration analysis using mRNA and miRNA is important to elucidate pathogenesis. However, their contribution, especially that of miRNA-targeted mRNA, to the severity of acute ischemic stroke remains unclear. Therefore, we examined mRNA and miRNA integration analysis targeted for acute ischemic stroke to clarify the pathway related to acute stroke severity.

MATERIAL AND METHODS

We performed Ingenuity Pathway Analysis (IPA) using RNA extracted from the whole blood of four healthy controls, six minor acute ischemic stroke patients (MS; National Institutes of Health Stroke Scale [NIHSS] < 8), and six severe acute ischemic stroke patients (SS; NIHSS ≥ 8) on admission. mRNA and miRNA were measured using RNA sequencing and RNA expression variation; canonical pathway analysis (CPA) and upstream regulator analyses were performed.

RESULTS

Acute ischemic stroke patients demonstrated different RNA expressions to healthy controls. Compared to MS patients, in the SS patients, 1222 mRNA, 96 miRNA, and 935 miRNA-targeted mRNA expressions were identified among differentially expressed RNA expressions (p<0.05, |log2 fold change| >1.1). CPA by IPA using mRNAs or miRNA-targeted mRNAs showed that macrophage-stimulating protein (MSP)-recepteur d'origine nantais (RON) signaling was mostly activated in SS patients compared to in MS patients. In addition, upstream regulator analysis in IPA showed that most mRNAs located upstream are miRNAs.

CONCLUSIONS

In severe acute stroke, integration of mRNA and microRNA analysis showed activated MSP-RON signaling in macrophages, and multiple miRNAs comprehensively controlled the overall pathophysiology of stroke.

The recent advancements in circRNA research: From biogenesis to therapeutic interventions

Circular RNAs (circRNAs) belong to the genre of long non-coding RNAs that are formed by special back-splicing events and are currently the molecule of interest for studies globally due their involvement in various ailments like diabetes, neurodegenerative disorders, cardio-vascular diseases and cancers. These class of highly stable RNAs participate in diverse cellular functionalities including microRNA (miRNA) sponging, ceRNA (competing endogenous RNA) activity or via exhibiting RNA binding protein (RBP) interactions. They are also known to regulate cancer progression both positively and negatively through various biological pathways such as, modulating the cell cycle and apoptotic pathways, epigenetic regulation, and translational and/or transcriptional regulations etc. Given its significance, a variety of computational tools and dedicated databases have been created for the identification, quantification, and differential expression of such RNAs in combination with sequencing approaches. In this review, we provide a comprehensive analysis of the numerous computational tools, pipelines, and online resources developed in recent years for the detection and annotation of circRNAs. We also summarise the most recent findings regarding the characteristics, functions, biological processes, and involvement of circRNAs in diseases. The review emphasises the significance of circRNAs as potential disease biomarkers and new treatment targets.

Liquid Biopsy in Neurological Diseases

The most recent and non-invasive approach for studying early-stage biomarkers is liquid biopsy. This implies the extraction and analysis of non-solid biological tissues (serum, plasma, saliva, urine, and cerebrospinal fluid) without undergoing invasive procedures to determine disease prognosis. Liquid biopsy can be used for the screening of several components, such as extracellular vesicles, microRNAs, cell-free DNA, cell-free mitochondrial and nuclear DNA, circulating tumour cells, circulating tumour DNA, transfer RNA, and circular DNA or RNA derived from body fluids. Its application includes early disease diagnosis, the surveillance of disease activity, and treatment response monitoring, with growing evidence for validating this methodology in cancer, liver disease, and central nervous system (CNS) disorders. This review will provide an overview of mentioned liquid biopsy components, which could serve as valuable biomarkers for the evaluation of complex neurological conditions, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, epilepsy, stroke, traumatic brain injury, CNS tumours, and neuroinfectious diseases. Furthermore, this review highlights the future directions and potential limitations associated with liquid biopsy.

Overexpression of Circ_0005585 Alleviates Cerebral Ischemia Reperfusion Injury via Targeting MiR-16-5p

Circular RNAs are implicated in the pathogenesis of ischemic stroke. In this work, we explored the modulation and potential mechanisms of action of circ_0005585 in ischemic stroke. Expression of circ_0005585 and miR-16-5p was assessed by quantitative real-time reverse transcription PCR. Ischemic stroke was modeled in mice by middle cerebral artery occlusion (MCAO). The infarct volume was assessed by triphenyl tetrazolium chloride staining. Neurological deficits were evaluated according to Neurological Severity Score. The permeability of the blood-brain barrier was assessed by Evan's blue leakage and brain water content. Apoptosis in brain tissues was measured by the TUNEL test. Relative expression of apoptosis-related proteins was evaluated by Western blotting. The direct interaction between circ_0005585 and miR-16-5p was verified by dual-luciferase reporter assay. The expression of circ_0005585 was lower in mice with MCAO. Lentivirus-mediated overexpression of circ_0005585 ameliorated the neurological deficits and decreased the infarction volume in MCAO mice. The brain water content and Evan's blue leakage through the blood-brain barrier were reduced. In addition, overexpression of circ_0005585 inhibited apoptosis in the cerebral tissues. Our results revealed direct interaction between circ_0005585 and miR-16-5p. Hence, circ_0005585 protects mouse brain during ischemic stroke by targeting miR-16-5p, which uncovers the pathogenesis of this pathology and opens new vitas for its therapy.

Circular RNA regulation and function in drug seeking phenotypes

Drug overdoses have increased dramatically in the United States over the last decade where they are now the leading cause of accidental death. To develop efficient therapeutic options for decreasing drug consumption and overdose risk, it is critical to understand the neurobiological changes induced by drug exposure. Chronic systemic exposure to all drug classes, including opioids, psychostimulants, nicotine, cannabis, and alcohol, induces profound molecular neuroadaptations within the central nervous system that may reveal crucial information about the lasting effects that these substances impart on brain cells. Transcriptome analyses of messenger RNAs (mRNAs) have identified gene patterns in the brain that result from exposure to various classes of drugs. However, mRNAs represent only a small fraction of the RNA within the cell, and drug exposure also impacts other classes of RNA that are largely understudied, especially circular RNAs. Circular RNAs (circRNAs) are a naturally occurring RNA species formed from back-splicing events during mRNA processing and are enriched in the nervous system. circRNAs are a pleiotropic class of RNAs and have a diverse impact on cellular function, with putative functions including regulation of mRNA transcription, protein translation, microRNA sponging, and sequestration of RNA-binding proteins. Recent studies have demonstrated that circRNAs can modulate cognition and are regulated in the brain in response to drug exposure, yet very few studies have explored the contribution of circRNAs to drug seeking phenotypes. In this review, we will provide an overview of the mechanisms of circRNA function in the cell to highlight how drug-induced circRNA dysregulation may impact the molecular substrates that mediate drug seeking behavior and the current studies that have reported drug-induced dysregulation of circRNAs in the brain. Furthermore, we will discuss how principles of circRNA biology can be adapted to study circRNAs in models of drug exposure and seek to provide further insight into the neurobiology of addiction.

CircPDS5B Reduction Improves Angiogenesis Following Ischemic Stroke by Regulating MicroRNA-223-3p/NOTCH2 Axis

Background and Objectives

Ischemic stroke (IS) is responsible for major causes of global death and disability, for which promoting angiogenesis is a promising therapeutic strategy. This study analyzed circular RNA PDS5B (circPDS5B) and its related mechanisms in angiogenesis in IS.

Methods

In the permanent middle cerebral artery occlusion (pMCAO) mouse model, circPDS5B, microRNA (miR)-223-3p, and NOTCH2 levels were checked. By testing neurologic function, neuronal apoptosis, and expression of angiogenesis-related proteins in pMCAO mice, the protective effects of circPDS5B knockdown were probed. In human brain microvascular endothelial cells (HBMECs) under oxygen-glucose deprivation (OGD) conditions, the effects of circPDS5B, miR-223-3p, and NOTCH2 on angiogenesis were studied by measuring cellular activities.

Results

The increase of circPDS5B and NOTCH2 expression and the decrease of miR-223-3p expression were examined in pMCAO mice. Reducing circPDS5B expression indicated protection against neurologic dysfunction, apoptosis, and angiogenesis impairment. For circPDS5B-depleted or miR-223-3p-restored HBMECs under OGD treatment, angiogenesis was promoted. MiR-223-3p inhibition-associated reduction of angiogenesis could be counteracted by knocking down NOTCH2. CircPDS5B depletion-induced angiogenesis in OGD-conditioned HBMECs was repressed after overexpressing NOTCH2.

Discussion

In IS, the expression of circPDS5B was upregulated, and miR-223-3p inhibited HBMECs activity and promoted NOTCH2 expression, thus promoting IS. CircPDS5B reduction improves angiogenesis following ischemic stroke by regulating microRNA-223-3p/NOTCH2 axis.

Astrocytic CXCL5 hinders microglial phagocytosis of myelin debris and aggravates white matter injury in chronic cerebral ischemia

BACKGROUND

Chronic cerebral ischemia induces white matter injury (WMI) contributing to cognitive decline. Both astrocytes and microglia play vital roles in the demyelination and remyelination processes, but the underlying mechanism remains unclear. This study aimed to explore the influence of the chemokine CXCL5 on WMI and cognitive decline in chronic cerebral ischemia and the underlying mechanism.

METHODS

Bilateral carotid artery stenosis (BCAS) model was constructed to mimic chronic cerebral ischemia in 7-10 weeks old male mice. Astrocytic Cxcl5 conditional knockout (cKO) mice were constructed and mice with Cxcl5 overexpressing in astrocytes were generated by stereotactic injection of adeno-associated virus (AAV). WMI was evaluated by magnetic resonance imaging (MRI), electron microscopy, histological staining and western blotting. Cognitive function was examined by a series of neurobehavioral tests. The proliferation and differentiation of oligodendrocyte progenitor cells (OPCs), phagocytosis of microglia were analyzed via immunofluorescence staining, western blotting or flow cytometry.

RESULTS

CXCL5 was significantly elevated in the corpus callosum (CC) and serum in BCAS model, mainly expressed in astrocytes, and Cxcl5 cKO mice displayed improved WMI and cognitive performance. Recombinant CXCL5 (rCXCL5) had no direct effect on the proliferation and differentiation of OPCs in vitro. Astrocytic specific Cxcl5 overexpression aggravated WMI and cognitive decline induced by chronic cerebral ischemia, while microglia depletion counteracted this effect. Recombinant CXCL5 remarkably hindered microglial phagocytosis of myelin debris, which was rescued by inhibition of CXCL5 receptor C-X-C motif chemokine receptor 2 (CXCR2).

CONCLUSION

Our study revealed that astrocyte-derived CXCL5 aggravated WMI and cognitive decline by inhibiting microglial phagocytosis of myelin debris, suggesting a novel astrocyte-microglia circuit mediated by CXCL5-CXCR2 signaling in chronic cerebral ischemia.

The Role of Circular RNAs in Ischemic Stroke

Ischemic stroke (IS), a devastating condition characterized by intracranial artery stenosis and middle cerebral artery occlusion leading to insufficient oxygen supply to the brain, is a major cause of death and physical disability worldwide. Recent research has demonstrated the critical role of circular RNAs (circRNAs), a class of covalently enclosed noncoding RNAs that are widespread in eukaryotic cells, in regulating various physiological and pathophysiological cellular processes, including cell apoptosis, autophagy, synaptic plasticity, and neuroinflammation. In the past few years, circRNAs have attracted extensive attention in the field of IS research. This review summarizes the current understanding of the mechanisms underlying the involvement of circRNAs in IS development. A better understanding of circRNA-mediated pathogenic mechanisms in IS may pave the way for translating circRNA research into clinical practice, ultimately improving the clinical outcomes of IS patients.

Circular RNA as biomarkers for acute ischemic stroke: A systematic review and meta-analysis

BACKGROUND

Rapid diagnosis of acute ischemic stroke (AIS) patients is still challenging, and reliable biomarkers are needed. Noncoding RNAs are important for many physiological activities, among which circular RNAs (circRNAs) have been proven to be more tissue-specific and conservative. Many recent studies found the potential of circRNAs as biomarkers for many diseases, including cardiovascular diseases, cancers, and ischemic stroke. This systemic review and meta-analysis aimed to identify circRNAs as potential biomarkers for AIS.

METHODS

This study has been prospectively registered in PROSPERO (Registration No. 11 CRD42021288033). Published literature comparing circRNA expression profiles between AIS and non-AIS in human and animal models were retrieved from the articles published by January 2023 in major databases. We descriptively summarized the included studies, conducted meta-analysis under a random effects model, and did bioinformatics analysis including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis.

RESULTS

Totally 23 studies were included, reporting 18 distinctive upregulated and 20 distinctive downregulated circRNAs. Diagnostic meta-analysis indicated discriminative ability of the circRNAs. Furthermore, circRNA HECTD1, circRNA DLGAP4, circRNA CDC14A, circRNA SCMH1, and circRNA TLK1 were reported with the same regulation trend in more than one study (animal studies included). GO and KEGG enrichment analyses indicated that the target genes of these five circRNAs were enriched in regulating cell proliferation, apoptosis, and oxidative stress.

CONCLUSIONS

This study demonstrates that circRNAs (circRNA HECTD1, circRNA DLGAP4, circRNA CDC14A, circRNA SCMH1, and circRNA TLK1) generally are promising as potential biomarkers for AIS. However, due to the limited number of studies, diagnostic value of individual circRNA could not be validated. More in vitro and in vivo functional studies are needed.

CircLPAR1 Promotes Neuroinflammation and Oxidative Stress in APP/PS1 Mice by Inhibiting SIRT1/Nrf-2/HO-1 Axis Through Destabilizing GDF-15 mRNA

Circular RNA LPAR1 (circLPAR1) was revealed to be elevated in Alzheimer's disease (AD); nevertheless, its role and mechanisms in AD remain unknown. Memory performance of APP/PS1 mice was assessed by Morris water maze test. Expression of circLPAR1 and indicated messenger RNA (mRNA) in mouse brain tissues or/and SH-SY5Y cells were tested by quantitative real-time PCR (qRT-PCR). Protein expression of indicated gene was examined by western blot. Production of proinflammatory cytokines (tumor necrosis factor-α, TNF-α; interleukin-6, IL-6; interleukin-1β, IL-1β; and interleukin-8, IL-8) and oxidative stress-related factors (reactive oxygen species, ROS; malondialdehyde, MDA; superoxide dismutase, SOD; and glutathione, GSH) were assessed by commercial kits. RNA pull down and RNA immunoprecipitation were performed to verify the interplay between up-frameshift protein 1 (UPF1) and circLPAR1 or growth differentiation factor 15 (GDF-15). CircLPAR1 was elevated, while GDF-15 was decreased in both APP/PS1 mice and Aβ-treated SH-SY5Y cells. Knockdown of circLPAR1 and overexpression of GDF-15 protected cells against Aβ-caused inflammation, oxidative stress, and neuronal apoptosis. CircLPAR1 knockdown was also proved to improve AD-related pathological traits and ameliorate cognitive dysfunctions in vivo. In mechanism, we found that circLPAR1 repressed GDF-15 expression by decreasing GDF-15 mRNA stability through UPF1 recruitment. Rescue assays suggested that sirtuin 1 (SIRT1) knockdown reversed GDF-15 overexpression-induced inhibition on Aβ-induced neuronal damage and nuclear factor E2-related factor (Nrf-2)/heme oxygenase-1 (HO-1) pathway inhibition. Moreover, the protective effect of circLPAR1 knockdown against Aβ-induced apoptosis was abolished by GDF-15 knockdown, and SIRT1 overexpression could counteract this effect of GDF-15 knockdown. CircLPAR1 knockdown improved AD-related pathological traits in vitro and in vivo by inhibiting SIRT1/Nrf-2/HO-1 axis through GDF-15.

Circular RNA CircPDS5B impairs angiogenesis following ischemic stroke through its interaction with hnRNPL to inactivate VEGF-A

BACKGROUND

Ischemic stroke (IS) is the primary cause of mortality and disability worldwide. Circular RNAs (circRNAs) have been proposed as crucial regulators in IS. This study focused on the role of circPDS5B in IS and its underlying mechanism.

METHOD

Transient middle cerebral artery occlusion (tMCAO) mice and glucose deprivation/reoxygenation (OGD/R)-exposed human brain microvascular endothelial cells (BMECs) were used as IS models. Expression levels of circPDS5B, heterogenous nuclear ribonucleoprotein L (hnRNPL), runt-related transcription factor-1 (Runx1), and Zinc finger protein 24 (ZNF24) were quantified by qRT-PCR. MTT, wound healing, transwell and tube formation assays were employed to evaluate the cell proliferation, migration, and angiogenesis, respectively. Moreover, RNA pull-down, and RIP assay were performed to investigate the interaction among circPDS5B, hnRNPL and vascular endothelial growth factor-A (VEGFA).

RESULTS

circPDS5B was significantly up-regulated in IS patients and tMCAO mice. Deficiency of circPDS5B relieved brain infarction and neuronal injury of tMCAO mice. OGD/R-induced apoptosis, inhibition in viability, migration, and angiogenesis in BMECs were dramatically abrogated by circPDS5B knockdown. Mechanistically, circPDS5B stabilized Runx1 and ZNF24 via recruiting hnRNPL, thereby suppressing the transcription and expression of VEGFA. hnRNPL silencing strengthened circPDS5B knockdown-mediated beneficial effect on IS.

CONCLUSION

Altogether, our study showed that high expression of circPDS5B exacerbated IS through recruitment of hnRNP to stabilize Runx1/ZNF24 and subsequently inactivate VEGF-A. Our findings suggest circPDS5B may be a novel therapeutic target for IS.

Silencing of the circ-Arhgap5 RNA protects neuronal PC12 cells against injury and depends on the miR-29a-3p/Rock1 axis

Circular RNAs (circRNAs) are abundantly expressed in human central nervous system. Here, we explored the role of circ_Arhgap5 in cerebral ischemia/reperfusion (I/R)-induced nerve injury in PC12 cells and its associated mechanism. Cell proliferation ability was assessed by 5-Ethynyl-2'-deoxyuridine (Edu) assay and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry (FCM) was applied to assess cell apoptotic rate. Cell death was analyzed by lactate dehydrogenase (LDH) assay. Oxygen-glucose deprivation and reoxygenation (OGD/R) up-regulates the expression of circRNA Rho GTPase activating protein 5 (circ_Arhgap5; mmu_circ_0000377) in PC12 cells. OGD/R exposure inhibited the proliferation and induced the apoptosis of PC12 cells, and the silence of circ_Arhgap5 attenuated OGD/R-induced injury in PC12 cells. miR-29a-3p was identified as a target of circ_Arhgap5 in PC12 cells. Circ_Arhgap5 knockdown-mediated protective effects in OGD/R-induced PC12 cells were reversed by the interference of miR-29a-3p. miR-29a-3p interacted with the 3' untranslated region (3'UTR) of Rho-associated coiled-coil-containing protein kinase 1 (Rock1), and circ_Arhgap5 can positively regulate Rock1 expression by sponging miR-29a-3p in PC12 cells. miR-29a-3p overexpression protected PC12 cells against OGD/R-induced damage by down-regulating Rock1. In conclusion, circ_Arhgap5 silencing protected PC12 cells from OGD/R-induced injury through mediating miR-29a-3p/Rock1 axis.

CircFOXP1 alleviates brain injury after acute ischemic stroke by regulating STAT3/apoptotic signaling

According to previous studies, circular RNAs (circRNAs) are involved in multiple pathological processes of acute ischemic stroke (AIS). However, the relationship between circFOXP1 and IS has not yet been reported. Here, we found that circFOXP1 expression was significantly decreased in the peripheral blood of AIS patients compared to controls and was associated with the severity and prognosis of AIS. Functionally, knockdown and overexpression of circFOXP1 promoted and inhibited apoptotic signaling, respectively, following oxygen-glucose deprivation/reperfusion (OGD/R) treatment in vitro. Adeno-associated virus (AAV)-mediated circFOXP1 overexpression attenuated neurological deficits and improved functional recovery after transient middle cerebral artery occlusion (tMCAO) treatment in vivo. Mechanistically, decreased QKI expression inhibited circFOXP1 biogenesis under hypoxic conditions. Decreased circFOXP1 expression accelerated signal transducer and activator of transcription 3 (STAT3) protein degradation by binding to and increasing STAT3 protein ubiquitination, ultimately aggravating brain injury after cerebral ischemia by activating apoptotic signaling. In summary, our study is the first to reveal that circFOXP1 alleviates brain injury after cerebral ischemia by regulating STAT3/apoptotic signaling, which provides a potentially novel therapeutic target for AIS.