Neuroprotective and regenerative roles of intranasal Wnt-3a administration after focal ischemic stroke in mice

Post-stroke cognitive impairment and brain hemorrhage are augmented in hypertensive mice

Hypertension is a major risk factor for both stroke and cognitive impairment, but it is unclear whether it may specifically affect post-stroke cognitive impairment. We assessed the effect of hypertension and/or stroke on brain injury, cognitive outcome, and the brain transcriptomic profile. C57BL/6J mice (n = 117; 3-5 mo.) received s.c. infusion of either saline or angiotensin II followed by sham surgery or photothrombotic stroke targeting the prefrontal cortex seven days later. Cognitive function was assessed with the Barnes maze and RNA sequencing was used to quantify transcriptomic changes in the brain. Angiotensin II treatment produced spontaneous hemorrhaging after stroke. In the Barnes maze, hypertensive mice that received stroke surgery had an increased escape latency compared to other groups (day 3: hypertensive + stroke = 166.6 ± 6.0 s vs. hypertensive + sham = 122.8 ± 13.8 s vs. normotensive + stroke = 139.9 ± 10.1 s vs. normotensive + sham = 101.9 ± 16.7 s), consistent with impaired cognition. RNA sequencing revealed >1500 differentially expressed genes related to neuroinflammation in hypertensive + stroke vs. normotensive + stroke, which included genes associated with apoptosis, microRNAs, autophagy, anti-cognitive biomarkers and Wnt signaling. Overall, we show that the combination of hypertension and stroke resulted in greater learning impairment and brain injury.

Intranasal Delivery of Anti-Apoptotic siRNA Complexed with Fas-Signaling Blocking Peptides Attenuates Cellular Apoptosis in Brain Ischemia

Ischemic stroke-induced neuronal cell death leads to the permanent impairment of brain function. The Fas-mediating extrinsic apoptosis pathway and the cytochrome c-mediating intrinsic apoptosis pathway are two major molecular mechanisms contributing to neuronal injury in ischemic stroke. In this study, we employed a Fas-blocking peptide (FBP) coupled with a positively charged nona-arginine peptide (9R) to form a complex with negatively charged siRNA targeting Bax (FBP9R/siBax). This complex is specifically designed to deliver siRNA to Fas-expressing ischemic brain cells. This complex enables the targeted inhibition of Fas-mediating extrinsic apoptosis pathways and cytochrome c-mediating intrinsic apoptosis pathways. Specifically, the FBP targets the Fas/Fas ligand signaling, while siBax targets Bax involved in mitochondria disruption in the intrinsic pathway. The FBP9R carrier system enables the delivery of functional siRNA to hypoxic cells expressing the Fas receptor on their surface-a finding validated through qPCR and confocal microscopy analyses. Through intranasal (IN) administration of FBP9R/siCy5 to middle cerebral artery occlusion (MCAO) ischemic rat models, brain imaging revealed the complex specifically localized to the Fas-expressing infarcted region but did not localize in the non-infarcted region of the brain. A single IN administration of FBP9R/siBax demonstrated a significant reduction in neuronal cell death by effectively inhibiting Fas signaling and preventing the release of cytochrome c. The targeted delivery of FBP9R/siBax represents a promising alternative strategy for the treatment of brain ischemia.

Effects of treadmill training on myelin proteomic markers and cerebellum morphology in a rat model of cuprizone-induced toxic demyelination

BACKGROUND

Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system (CNS). If demyelination is persistent, it will result in irreversible axonal injury and loss. The purpose of the current study was to investigate the effects of treadmill training on myelin proteomic markers and cerebellum morphology in a rat model of cuprizone-induced toxic demyelination.

METHODS

Thirty male rats were randomly assigned to five groups (n = 6 per group), consisting of a healthy control group (Control), a cuprizone (CPZ) group, and three exercise training groups: exercise training before and during the CPZ administration (EX-CPZ-EX), exercise training before the CPZ administration (EX-CPZ), and exercise training during the CPZ administration (CPZ-EX). A rat model of CPZ-induced toxic demyelination consisted of feeding the rats cuprizone pellets (0.2%) for 6 weeks. All exercise groups performed a treadmill training protocol 5 days/week for 6 weeks. Levels of Myelin proteolipid protein (PLP), Myelin oligodendrocyte glycoprotein (MOG), axonal injury in the cerebellar tissue, and volume, weight, and length of the cerebellum were determined.

RESULTS

Results indicated a significant decrease in PLP and MOG in the CPZ groups compared to the Control group (****p < 0.0001). There was a significant increase in PLP and MOG and a significant decrease in axonal injury in the EX-CPZ-EX group as compared to other CPZ groups (****p < 0.0001), and CPZ-MS and CPZ-EX were not significantly different from one another. However, there were no significant differences between the groups for the volume, weight, or length of the cerebellum.

CONCLUSION

Treadmill training improved myelin sheath structural proteins and axonal injury in cerebellar tissue in a rat model of CPZ-induced toxic demyelination.

Therapeutic Potential of Natural Compounds from Herbs and Nutraceuticals in Alleviating Neurological Disorders: Targeting the Wnt Signaling Pathway

As an important signaling pathway in multicellular eukaryotes, the Wnt signaling pathway participates in a variety of physiological processes. Recent studies have confirmed that the Wnt signaling pathway plays an important role in neurological disorders such as stroke, Alzheimer's disease, and Parkinson's disease. The regulation of Wnt signaling by natural compounds in herbal medicines and nutraceuticals has emerged as a potential strategy for the development of new drugs for neurological disorders. Purpose: The aim of this review is to evaluate the latest research results on the efficacy of natural compounds derived from herbs and nutraceuticals in the prevention and treatment of neurological disorders by regulating the Wnt pathway in vivo and in vitro. A manual and electronic search was performed for English articles available from PubMed, Web of Science, and ScienceDirect from the January 2010 to February 2023. Keywords used for the search engines were "natural products,″ "plant derived products,″ "Wnt+ clinical trials,″ and "Wnt+,″ and/or paired with "natural products″/″plant derived products", and "neurological disorders." A total of 22 articles were enrolled in this review, and a variety of natural compounds from herbal medicine and nutritional foods have been shown to exert therapeutic effects on neurological disorders through the Wnt pathway, including curcumin, resveratrol, and querctrin, etc. These natural products possess antioxidant, anti-inflammatory, and angiogenic properties, confer neurovascular unit and blood-brain barrier integrity protection, and affect neural stem cell differentiation, synaptic formation, and neurogenesis, to play a therapeutic role in neurological disorders. In various in vivo and in vitro studies and clinical trials, these natural compounds have been shown to be safe and tolerable with few adverse effects. Natural compounds may serve a therapeutic role in neurological disorders by regulating the Wnt pathway. This summary of the research progress of natural compounds targeting the Wnt pathway may provide new insights for the treatment of neurological disorders and potential targets for the development of new drugs.

Ischemia-reperfusion injury: molecular mechanisms and therapeutic targets

Ischemia-reperfusion (I/R) injury paradoxically occurs during reperfusion following ischemia, exacerbating the initial tissue damage. The limited understanding of the intricate mechanisms underlying I/R injury hinders the development of effective therapeutic interventions. The Wnt signaling pathway exhibits extensive crosstalk with various other pathways, forming a network system of signaling pathways involved in I/R injury. This review article elucidates the underlying mechanisms involved in Wnt signaling, as well as the complex interplay between Wnt and other pathways, including Notch, phosphatidylinositol 3-kinase/protein kinase B, transforming growth factor-β, nuclear factor kappa, bone morphogenetic protein, N-methyl-D-aspartic acid receptor-Ca2+-Activin A, Hippo-Yes-associated protein, toll-like receptor 4/toll-interleukine-1 receptor domain-containing adapter-inducing interferon-β, and hepatocyte growth factor/mesenchymal-epithelial transition factor. In particular, we delve into their respective contributions to key pathological processes, including apoptosis, the inflammatory response, oxidative stress, extracellular matrix remodeling, angiogenesis, cell hypertrophy, fibrosis, ferroptosis, neurogenesis, and blood-brain barrier damage during I/R injury. Our comprehensive analysis of the mechanisms involved in Wnt signaling during I/R reveals that activation of the canonical Wnt pathway promotes organ recovery, while activation of the non-canonical Wnt pathways exacerbates injury. Moreover, we explore novel therapeutic approaches based on these mechanistic findings, incorporating evidence from animal experiments, current standards, and clinical trials. The objective of this review is to provide deeper insights into the roles of Wnt and its crosstalk signaling pathways in I/R-mediated processes and organ dysfunction, to facilitate the development of innovative therapeutic agents for I/R injury.

Olfactory bulb neurogenesis depending on signaling in the subventricular zone

Olfaction is a crucial sense that is essential for the well-being and survival of individuals. Olfactory bulb (OB) is the first olfactory relay station, and its function depends on newly generated neurons from the subventricular zone (SVZ). These newly born neurons constantly migrate through the rostral migratory stream to integrate into existing neural networks within the OB, thereby contributing to olfactory information processing. However, the mechanisms underlying the contribution of SVZ adult neurogenesis to OB neurogenesis remain largely elusive. Adult neurogenesis is a finely regulated multistep process involving the proliferation of adult neural stem cells (aNSCs) and neural precursor cells, as well as the migration and differentiation of neuroblasts, and integration of newly generated neurons into preexisting neuronal circuitries. Recently, extensive studies have explored the mechanism of SVZ and OB neurogenesis. This review focused on elucidating various molecules and signaling pathways associated with OB neurogenesis dependent on the SVZ function. A better understanding of the mechanisms underlying the OB neurogenesis on the adult brain is an attractive prospect to induce aNSCs in SVZ to generate new neurons to ameliorate olfactory dysfunction that is involved in various diseases. It will also contribute to developing new strategies for the human aNSCs-based therapies.

Neuroprotective Effect of Hydrogen Sulfide Subchronic Treatment Against TBI-Induced Ferroptosis and Cognitive Deficits Mediated Through Wnt Signaling Pathway

Emerging evidence shows that targeting ferroptosis may be a potential therapeutic strategy for treating traumatic brain injury (TBI). Hydrogen sulfide (H2S) has been proven to play a neuroprotective role in TBI, but little is known about the effects of H2S on TBI-induced ferroptosis. In addition, it is reported that the Wnt signaling pathway can also actively regulate ferroptosis. However, whether H2S inhibits ferroptosis via the Wnt signaling pathway after TBI remains unclear. In this study, we first found that in addition to alleviating neuronal damage and cognitive impairments, H2S remarkably attenuated abnormal iron accumulation, decreased lipid peroxidation, and improved the expression of glutathione peroxidase 4, demonstrating the potent anti-ferroptosis action of H2S after TBI. Moreover, Wnt3a or liproxstatin-1 treatment obtained similar results, suggesting that activation of the Wnt signaling pathway can render the cells less susceptible to ferroptosis post-TBI. More importantly, XAV939, an inhibitor of the Wnt signaling pathway, almost inversed ferroptosis inactivation and reduction of neuronal loss caused by H2S treatment, substantiating the involvement of the Wnt signaling pathway in anti-ferroptosis effects of H2S. In conclusion, the Wnt signaling pathway might be the critical mechanism in realizing the anti-ferroptosis effects of H2S against TBI. TBI induces ferroptosis-related changes characterized by iron overload, impaired antioxidant system, and lipid peroxidation at the chronic phase after TBI. However, NaHS subchronic treatment reduces the susceptibility to TBI-induced ferroptosis, at least partly by activating the Wnt signaling pathway.

Exendin-4 ameliorates tau hyperphosphorylation and cognitive impairment in type 2 diabetes through acting on Wnt/β-catenin/NeuroD1 pathway

BACKGROUND

Type 2 diabetes (T2D) is an independent risk factor for Alzheimer's disease (AD). Exendin-4 (Ex-4), a widely used glucagon-like peptide-1 receptor agonist drug in the treatment of T2D, has been demonstrated the therapeutic effects on diabetic encephalopathy (DE). Especially, the Ex-4 ameliorates the tau hyperphosphorylation and cognitive impairment in DE. And these crucial alterations are also important bridge between T2D and AD. However, its unique mechanism is unclear.

METHODS

The db/db mice, high-fat-diet (HFD) / streptozotocin (STZ)-induced diabetic (HF-diabetic) mice, and high-glucose-damaged (HGD) HT-22 hippocampal cells were enrolled to examine the effects of Ex-4 on AD-like changes in T2D. The Novel object recognition test (NORT) and Morris water maze test (MWMT) were conducted to evaluate the cognitive impairment. The Dickkopf-1 (DKK1) was employed to weaken the activation of the Wnt/β-catenin pathway to explore the mechanism of Ex-4 in protecting the brain functions. The JASPAR was based to predict the interaction between NeuroD1 and the promoter region of Ins2. Moreover, the chromatin immunoprecipitation coupled with quantitative polymerase chain reaction (ChIP-qPCR) and luciferase reporter assays were performed.

RESULTS

Ex-4 alleviated the tau hyperphosphorylation, increased the brain-derived insulin, and improved the PI3K/AKT/GSK3-β signalling in db/db mice, HF-diabetic mice, and HGD HT-22 hippocampal neuronal cells. The NORT and MWMT indicated that Ex-4 alleviated the learning and memory deficits in HF-diabetic mice. The inhibitor Dickkopf-1 (DKK1) of the Wnt/β-catenin pathway significantly blocked the protective effects of Ex-4. Regarding further molecular mechanisms, NeuroD1 was affected by Ex-4 in vivo and in vitro, and the knockdown or overexpression of NeuroD1 suggested its crucial role in promoting the brain insulin by Ex-4. Meanwhile, the ChIP‒qPCR and luciferase reporter assays confirmed the combination between NeuroD1 and the promoter region of the insulin-encoding gene Ins2. And this interaction could be promoted by Ex-4.

CONCLUSIONS

Our study proposes that Ex-4 alleviates tau hyperphosphorylation and cognitive dysfunction by increasing Ins2-derived brain insulin through the Wnt/β-catenin/NeuroD1 signaling in T2D. And its also show new lights on part of the progress and mechanism on treatment targets for the DE in T2D.

Targeting the cochlin/SFRP1/CaMKII axis in the ocular posterior pole prevents the progression of nonpathologic myopia

Myopia is a major public health issue. However, interventional modalities for nonpathologic myopia are limited due to its complicated pathogenesis and the lack of precise targets. Here, we show that in guinea pig form-deprived myopia (FDM) and lens-induced myopia (LIM) models, the early initiation, phenotypic correlation, and stable maintenance of cochlin protein upregulation at the interface between retinal photoreceptors and retinal pigment epithelium (RPE) is identified by a proteomic analysis of ocular posterior pole tissues. Then, a microarray analysis reveals that cochlin upregulates the expression of the secreted frizzled-related protein 1 (SFRP1) gene in human RPE cells. Moreover, SFRP-1 elevates the intracellular Ca2+ concentration and activates Ca2+/calmodulin-dependent protein kinase II (CaMKII) signaling in a simian choroidal vascular endothelial cell line, and elicits vascular endothelial cell dysfunction. Furthermore, genetic knockdown of the cochlin gene and pharmacological blockade of SFRP1 abrogates the reduced choroidal blood perfusion and prevents myopia progression in the FDM model. Collectively, this study identifies a novel signaling axis that may involve cochlin in the retina, SFRP1 in the RPE, and CaMKII in choroidal vascular endothelial cells and contribute to the pathogenesis of nonpathologic myopia, implicating the potential of cochlin and SFRP1 as myopia interventional targets.

Bilateral transcranial direct-current stimulation promotes migration of subventricular zone-derived neuroblasts toward ischemic brain

Ischemic insult stimulates proliferation of neural stem cells (NSCs) in the subventricular zone (SVZ) after stroke. However, only a fraction of NSC-derived neuroblasts from SVZ migrate toward poststroke brain region. We have previously reported that direct-current stimulation guides NSC migration toward the cathode in vitro. Accordingly, we set up a new method of transcranial direct-current stimulation (tDCS), in which the cathodal electrode is placed on the ischemic hemisphere and anodal electrode on the contralateral hemisphere of rats subjected to ischemia-reperfusion injury. We show that the application of this bilateral tDCS (BtDCS) promotes the migration of NSC-derived neuroblasts from SVZ toward the cathode direction into poststroke striatum. Reversing the position of the electrodes blocks the effect of BtDCS on the migration of neuroblasts from SVZ. BtDCS protects against neuronal death and improves the functional recovery of stroke animals. Thus, the migration of NSC-derived neuroblasts from SVZ toward poststroke brain region contributes to the effect of BtDCS against ischemia-induced neuronal death, supporting a potential development of noninvasive BtDCS as an endogenous neurogenesis-based stroke therapy.

Therapeutic Potential of Chinese Medicine for Endogenous Neurogenesis: A Promising Candidate for Stroke Treatment

Strokes are a leading cause of morbidity and mortality in adults worldwide. Extensive preclinical studies have shown that neural-stem-cell-based treatments have great therapeutic potential for stroke. Several studies have confirmed that the effective components of traditional Chinese medicine can protect and maintain the survival, proliferation, and differentiation of endogenous neural stem cells through different targets and mechanisms. Therefore, the use of Chinese medicines to activate and promote endogenous nerve regeneration and repair is a potential treatment option for stroke patients. Here, we summarize the current knowledge regarding neural stem cell strategies for ischemic strokes and the potential effects of these Chinese medicines on neuronal regeneration.

Neuropilin-1 promotes mitochondrial structural repair and functional recovery in rats with cerebral ischemia

OBJECTIVES

Available literature documents that ischemic stroke can disrupt the morphology and function of mitochondria and that the latter in other disease models can be preserved by neuropilin-1 (NRP-1) via oxidative stress suppression. However, whether NRP-1 can repair mitochondrial structure and promote functional recovery after cerebral ischemia is still unknown. This study tackled this very issue and explored the underlying mechanism.

METHODS

Adeno-associated viral (AAV)-NRP-1 was stereotaxically inoculated into the cortex and ipsilateral striatum posterior of adult male Sprague-Dawley (SD) rats before a 90-min transient middle cerebral artery occlusion (tMCAO) and subsequent reperfusion. Lentivirus (LV)-NRP-1 was transfected into rat primary cortical neuronal cultures before a 2-h oxygen-glucose deprivation and reoxygenation (OGD/R) injury to neurons. The expression and function of NRP-1 and its specific protective mechanism were investigated by Western Blot, immunofluorescence staining, flow cytometry, magnetic resonance imaging, transmission electron microscopy, etc. The binding was detected by molecular docking and molecular dynamics simulation.

RESULTS

Both in vitro and in vivo models of cerebral ischemia/reperfusion (I/R) injury presented a sharp increase in NRP-1 expression. The expression of AAV-NRP-1 markedly ameliorated the cerebral I/R-induced damage to the motor function and restored the mitochondrial morphology. The expression of LV-NRP-1 alleviated mitochondrial oxidative stress and bioenergetic deficits. AAV-NRP-1 and LV-NRP-1 treatments increased the wingless integration (Wnt)-associated signals and β-catenin nuclear localization. The protective effects of NRP-1 were reversed by the administration of XAV-939.

CONCLUSIONS

NRP-1 can produce neuroprotective effects against I/R injury to the brain by activating the Wnt/β-catenin signaling pathway and promoting mitochondrial structural repair and functional recovery, which may serve as a promising candidate target in treating ischemic stroke.

Bradykinin/bradykinin 1 receptor promotes brain microvascular endothelial cell permeability and proinflammatory cytokine release by downregulating Wnt3a

Stroke is a life-threatening disease with limited therapeutic options. Damage to the blood-brain barrier (BBB) is the key pathological feature of ischemic stroke. This study explored the role of the bradykinin (BK)/bradykinin 1 receptor (B1R) and its mechanism of action in the BBB. Human brain microvascular endothelial cells (BMECs) were used to test for cellular responses to BK by using the Cell Counting Kit-8 assay, 5-ethynyl-2'-deoxyuridine staining, enzyme-linked immunosorbent assay, flow cytometry, immunofluorescence, cellular permeability assays, and western blotting to evaluate cell viability, cytokine production, and reactive oxygen species (ROS) levels in vitro. A BBB induced by middle cerebral artery occlusion was used to evaluate BBB injuries, and the role played by BK/B1R in ischemic/reperfusion (I/R) was explored in a rat model. Results showed that BK reduced the viability of BMECs and increased the levels of proinflammatory cytokines (interleukin 6 [IL-6], IL-18, and monocyte chemoattractant protein-1) and ROS. Additionally, cellular permeability was increased by BK treatment, and the expression of tight junction proteins (claudin-5 and occludin) was decreased. Interestingly, Wnt3a expression was inhibited by BK and exogenous Wnt3a restored the effects of BK on BMECs. In an in vivo I/R rat model, knockdown of B1R significantly decreased infarct volume and inflammation in I/R rats. Our results suggest that BK might be a key inducer of BBB injury and B1R knockdown might provide a beneficial effect by upregulating Wnt3a.

Overexpression of Brain- and Glial Cell Line-Derived Neurotrophic Factors Is Neuroprotective in an Animal Model of Acute Hypobaric Hypoxia

Currently, the role of the neurotrophic factors BDNF and GDNF in maintaining the brain’s resistance to the damaging effects of hypoxia and functional recovery of neural networks after exposure to damaging factors are actively studied. The assessment of the effect of an increase in the level of these neurotrophic factors in brain tissues using genetic engineering methods on the resistance of laboratory animals to hypoxia may pave the way for the future clinical use of neurotrophic factors BDNF and GDNF in the treatment of hypoxic damage. This study aimed to evaluate the antihypoxic and neuroprotective properties of BDNF and GDNF expression level increase using adeno-associated viral vectors in modeling hypoxia in vivo. To achieve overexpression of neurotrophic factors in the central nervous system’s cells, viral constructs were injected into the brain ventricles of newborn male C57Bl6 (P0) mice. Acute hypobaric hypoxia was modeled on the 30th day after the injection of viral vectors. Survival, cognitive, and mnestic functions in the late post-hypoxic period were tested. Evaluation of growth and weight characteristics and the neurological status of animals showed that the overexpression of neurotrophic factors does not affect the development of mice. It was found that the use of adeno-associated viral vectors increased the survival rate of male mice under hypoxic conditions. The present study indicates that the neurotrophic factors’ overexpression, induced by the specially developed viral constructs carrying the BDNF and GDNF genes, is a prospective neuroprotection method, increasing the survival rate of animals after hypoxic injury.

Chrysophanol Ameliorates Hemin-Induced Oxidative Stress and Endoplasmic Reticulum Stress by Regulating MicroRNA-320-5p/Wnt3a Pathway in HT22 Cells

Oxidative stress, endoplasmic reticulum (ER) stress, and neuronal cell apoptosis have been considered as the main pathogenesis factors of brain injury after intracerebral hemorrhage (ICH). Chrysophanol (CHR) has been proved to have neuroprotective effects, but the role and underlying mechanisms of CHR in ICH remain unclear. HT22 cells were dealt with hemin to mimic an in vitro ICH model and then subjected to treatment with or without CHR. The cell viability, apoptosis, ER stress, and oxidative stress were evaluated by conducting the cell counting kit-8 (CCK-8), TdT-mediated dUTP nick end labeling (TUNEL) staining assays, western blot, and corresponding kit, respectively. Further, microRNA-sequencing, bioinformatic analysis, dual-luciferase reporter method, and rescue experiments were conducted to explore the molecular mechanisms of CHR alleviating hemin-induced ER in HT22 cell. Our data revealed that CHR increased cells viability, antiapoptosis, anti-ER stress, and antioxidative stress under conditions of hemin-induced HT22 cell injury. Mechanically, it was observed that Wnt3a was competitively sponged by miR-320-5p, and CHR activated β-catenin pathway by regulating miR-320-5p/Wnt3a molecular axis. Finally, results from the rescue experiment suggested that CHR inhibited hemin-induced cells apoptosis, ER stress, and oxidative stress through regulating the miR-320-5p/Wnt3a axis in HT22 cells. In conclusion, CHR prevented hemin-induced apoptosis, ER stress, and oxidative stress via inhibiting the miR-320-5p/Wnt3a/β-catenin pathway in HT22 cells. Our results certified that CHR could be served as a promising treatment for brain damage following ICH.

Differential Expression and Correlation Analysis of Global Transcriptome for Hemorrhagic Transformation After Acute Ischemic Stroke

In order to explore the epigenetic characteristics of hemorrhagic transformation (HT) after acute ischemic stroke, we used transcriptome sequencing technology to analyze the global transcriptome expression profile of patients with and without HT after acute ischemic stroke and to study the differential expression of messenger RNA (mRNA), long noncoding RNA (lncRNA), circular RNA (circRNA) and mircoRNA (miRNA) between the two groups. To further explore the role of differentially expressed genes in HT, we annotated the function of differentially expressed genes by using gene ontology (GO) and pathway analysis on the results and showed that there were 1,051 differential expressions of lncRNAs, 2,575 differential expressions of mRNAs, 447 differential expressions of circRNAs and 47 miRNAs in patients with HT compared with non-HT patients. Pathway analysis showed that ubiquitin-mediated proteolysis, MAPK signal pathway, axon guidance, HIF-1 signal pathway, NOD-like receptor signal pathway, beta-alanine metabolism, Wnt signal pathway, sphingolipid signal pathway, neuroactive ligand-receptor interaction, and intestinal immune network used in IgA production play an important role in HT. Terms such as iron homeostasis, defense response, immune system process, DNA conformational change, production of transforming growth factor beta-2, and oxidoreductase activity were enriched in the gene list, suggesting a potential correlation with HT. A total of 261 lncRNA-miRNA relationship pairs and 21 circRNA-miRNA relationship pairs were obtained; additionally, 5 circRNAs and 13 lncRNAs were screened, which can be used as competing endogenous RNA (ceRNA) to compete with miRNA in the co-expression network. Co-expression network analysis shows that these differentially expressed circRNA and lncRNA may play a vital role in HT and provide valuable information for new biomarkers or therapeutic targets.

Activation of Wnt/Beta-Catenin Signaling Pathway as a Promising Therapeutic Candidate for Cerebral Ischemia/Reperfusion Injury

Stroke is one of the leading causes of mortality, and survivors experience serious neurological and motor behavioral deficiencies. Following a cerebral ischemic event, substantial alterations in both cellular and molecular activities occur because of ischemia/reperfusion injury. Wnt signaling is an evolutionarily conserved signaling pathway that has been manifested to play a key role in embryo development and function maintenance in adults. Overactivation of Wnt signaling has previously been investigated in cancer-based research studies. Recently, abnormal Wnt signaling activity has been observed in ischemic stroke, which is accompanied by massive blood–brain barrier (BBB) disruption, neuronal apoptosis, and neuroinflammation within the central nervous system (CNS). Significant therapeutic effects were observed after reactivating the adynamic signaling activity of canonical Wnt signaling in different cell types. To better understand the therapeutic potential of Wnt as a novel target for stroke, we reviewed the role of Wnt signaling in the pathogenesis of stroke in different cell types, including endothelial cells, neurons, oligodendrocytes, and microglia. A comprehensive understanding of Wnt signaling among different cells may help to evaluate its potential value for the development of novel therapeutic strategies based on Wnt activation that can ameliorate complications and improve functional rehabilitation after ischemic stroke.

LncRNA NEAT1 stabilized Wnt3a via U2AF2 and activated Wnt/β-catenin pathway to alleviate ischemia stroke induced injury

BACKGROUND

Ischaemic stroke is the leading cause of mortality and disability in the world. LncRNA NEAT1 has been shown to play an important role in ischaemic injury, but the molecular mechanism remains unclear.

METHODS

qRT-PCR was used to determine the expression of lncRNA NEAT1 in OGD/R-induced BV-2 cells. Cell viability was assessed by an MTT assay, and cell apoptosis was assessed by flow cytometry. The expression of related proteins was evaluated by Western blotting and ELISA. The interactions among lncRNA NEAT1, U2AF2 and Wnt3a mRNA was demonstrated by RIP and RNA pulldown assays. XAV-939 was used as an inhibitor of the Wnt/β-catenin pathway.

RESULTS

LncRNA NEAT1 was found to be downregulated in OGD/R-induced BV-2 cells. Overexpression of lncRNA NEAT1 protected BV-2 cells against OGD/R-induced injury. LncRNA NEAT1 enhanced the stability of Wnt3a mRNA via U2AF2. Knockdown of Wnt3a or blockade of the Wnt/β-catenin pathway rescued the effect of lncRNA NEAT1.

CONCLUSIONS

LncRNA NEAT1 protected cells against OGD/R-induced apoptosis and the inflammatory response by activating the Wnt/β-catenin pathway through upregulation of Wnt3a in a U2AF2-dependent manner. LncRNA NEAT1 could be a promising therapeutic candidate for ischaemic stroke treatment in the future.

Primary cilia and ciliary signaling pathways in aging and age-related brain disorders

Brain disorders are characterized by the progressive loss of structure and function of the brain as a consequence of progressive degeneration and/or death of nerve cells. Aging is a major risk factor for brain disorders such as Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and stroke. Various cellular and molecular events have been shown to play a role in the progress of neurodegenerative diseases. Emerging studies suggest that primary cilia could be a key regulator in brain diseases. The primary cilium is a singular cellular organelle expressed on the surface of many cell types, such as astrocytes and neurons in the mature brain. Primary cilia detect extracellular cues, such as Sonic Hedgehog (SHH) protein, and transduce these signals into cells to regulate various signaling pathways. Abnormalities in ciliary length and frequency (ratio of ciliated cells) have been implicated in various human diseases, including brain disorders. This review summarizes current findings and thoughts on the role of primary cilia and ciliary signaling pathways in aging and age-related brain disorders.

rhFGF20 promotes angiogenesis and vascular repair following traumatic brain injury by regulating Wnt/β-catenin pathway

The pathology of cerebrovascular disorders takes an important role in traumatic brain injury (TBI) by increasing intracranial pressure. Fibroblast growth factor 20 (FGF20) is a brain-derived neurotrophic factor, that has been shown to play an important role in the survival of dopaminergic neurons and the treatment of Parkinson's disease (PD). However, little is known about the role of FGF20 in the treatment of TBI and its underlying mechanism. The purpose of this study was to evaluate the protective effect of recombinant human FGF20 (rhFGF20) on protecting cerebral blood vessels after TBI. In this study, we indicated that rhFGF20 could reduce brain edema, Evans blue penetration and upregulated the expression of blood-brain barrier (BBB)-related tight junction (TJ) proteins, exerting a protective effect on the BBB in vivo after TBI. In the TBI repair phase, rhFGF20 promoted angiogenesis, neurological and cognitive function recovery. In tumor necrosis factor-α (TNF-α)-induced human brain microvascular endothelial cells (hCMEC/D3), an in vitro BBB disruption model, rhFGF20 reversed the impairment in cell migration and tube formation induced by TNF-α. Moreover, in both the TBI mouse model and the in vitro model, rhFGF20 increased the expression of β-catenin and GSK3β, which are the two key regulators in the Wnt/β-catenin signaling pathway. In addition, the Wnt/β-catenin inhibitor IWR-1-endo significantly reversed the effects of rhFGF20. These results indicate that rhFGF20 may prevent vascular repair and angiogenesis through the Wnt/β-catenin pathway.

Neuroprotective Effects of GV1001 in Animal Stroke Model and Neural Cells Subject to Oxygen-Glucose Deprivation/Reperfusion Injury

Background and Purpose

Previous studies have revealed the diverse neuroprotective effects of GV1001. In this study, we investigated the effects of GV1001 on focal cerebral ischemia-reperfusion injury (IRI) in rats and oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injury in neural stem cells (NSCs) and cortical neurons.

Methods

Focal cerebral IRI was induced by transient middle cerebral artery occlusion (MCAO). Brain diffusion-weighted imaging (DWI) was performed 2 hours after occlusion, and a total of 37 rats were treated by reperfusion with GV1001 or saline 2 hours after occlusion. Fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging, immunohistochemistry, and neurobehavioral function analyses were performed. Additionally, OGD/R-injured NSCs and cortical neurons were treated with different GV1001 concentrations. Cell viability, proliferation, migration, and oxidative stress were determined by diverse molecular analyses.

Results

In the stroke model, GV1001 protected neural cells against IRI. The most effective dose of GV1001 was 60 μM/kg. The infarct volume on FLAIR 48 hours after MCAO compared to lesion volume on DWI showed a significantly smaller ratio in the GV1001-treated group. GV1001-treated rats exhibited better behavioral functions than the saline-treated rats. Treatment with GV1001 increased the viability, proliferation, and migration of the OGD/R-injured NSCs. Free radicals were significantly restored by treatment with GV1001. These neuroprotective effects of GV1001 have also been demonstrated in OGD/R-injured cortical neurons.

Conclusions

The results suggest that GV1001 has neuroprotective effects against IRI in NSCs, cortical neurons, and the rat brain. These effects are mediated through the induction of cellular proliferation, mitochondrial stabilization, and anti-apoptotic, anti-aging, and antioxidant effects.

Bioinformatic analysis for potential biological processes and key targets of heart failure-related stroke

This study aimed to uncover underlying mechanisms and promising intervention targets of heart failure (HF)-related stroke. HF-related dataset GSE42955 and stroke-related dataset GSE58294 were obtained from the Gene Expression Omnibus (GEO) database. Weighted gene co-expression network analysis (WGCNA) was conducted to identify key modules and hub genes. Gene Ontology (GO) and pathway enrichment analyses were performed on genes in the key modules. Genes in HF- and stroke-related key modules were intersected to obtain common genes for HF-related stroke, which were further intersected with hub genes of stroke-related key modules to obtain key genes in HF-related stroke. Key genes were functionally annotated through GO in the Reactome and Cytoscape databases. Finally, key genes were validated in these two datasets and other datasets. HF- and stroke-related datasets each identified two key modules. Functional enrichment analysis indicated that protein ubiquitination, Wnt signaling, and exosomes were involved in both HF- and stroke-related key modules. Additionally, ten hub genes were identified in stroke-related key modules and 155 genes were identified as common genes in HF-related stroke. OTU deubiquitinase with linear linkage specificity(OTULIN) and nuclear factor interleukin 3-regulated(NFIL3) were determined to be the key genes in HF-related stroke. Through functional annotation, OTULIN was involved in protein ubiquitination and Wnt signaling, and NFIL3 was involved in DNA binding and transcription. Importantly, OTULIN and NFIL3 were also validated to be differentially expressed in all HF and stroke groups. Protein ubiquitination, Wnt signaling, and exosomes were involved in HF-related stroke. OTULIN and NFIL3 may play a key role in HF-related stroke through regulating these processes, and thus serve as promising intervention targets.

GPR37 modulates progenitor cell dynamics in a mouse model of ischemic stroke

The generation of neural stem and progenitor cells following injury is critical for the function of the central nervous system, but the molecular mechanisms modulating this response remain largely unknown. We have previously identified the G protein-coupled receptor 37 (GPR37) as a modulator of ischemic damage in a mouse model of stroke. Here we demonstrate that GPR37 functions as a critical negative regulator of progenitor cell dynamics and gliosis following ischemic injury. In the central nervous system, GPR37 is enriched in mature oligodendrocytes, but following injury we have found that its expression is dramatically increased within a population of Sox2-positive progenitor cells. Moreover, the genetic deletion of GPR37 did not alter the number of mature oligodendrocytes following injury but did markedly increase the number of both progenitor cells and injury-induced Olig2-expressing glia. Alterations in the glial environment were further evidenced by the decreased activation of oligodendrocyte precursor cells. These data reveal that GPR37 regulates the response of progenitor cells to ischemic injury and provides new perspectives into the potential for manipulating endogenous progenitor cells following stroke.

The Role of Astrocytes in the Neurorepair Process

Astrocytes are highly specialized glial cells responsible for trophic and metabolic support of neurons. They are associated to ionic homeostasis, the regulation of cerebral blood flow and metabolism, the modulation of synaptic activity by capturing and recycle of neurotransmitters and maintenance of the blood-brain barrier. During injuries and infections, astrocytes act in cerebral defense through heterogeneous and progressive changes in their gene expression, morphology, proliferative capacity, and function, which is known as reactive astrocytes. Thus, reactive astrocytes release several signaling molecules that modulates and contributes to the defense against injuries and infection in the central nervous system. Therefore, deciphering the complex signaling pathways of reactive astrocytes after brain damage can contribute to the neuroinflammation control and reveal new molecular targets to stimulate neurorepair process. In this review, we present the current knowledge about the role of astrocytes in brain damage and repair, highlighting the cellular and molecular bases involved in synaptogenesis and neurogenesis. In addition, we present new approaches to modulate the astrocytic activity and potentiates the neurorepair process after brain damage.

Baicalin promotes hippocampal neurogenesis via the Wnt/β-catenin pathway in a chronic unpredictable mild stress-induced mouse model of depression

Hippocampal neurogenesis is known to be related to depressive symptoms. Increasing evidence indicates that Wnt/β-catenin signaling regulates multiple aspects of adult hippocampal neurogenesis. Baicalin is a major flavonoid compound with multiple pharmacological effects such as anti-inflammatory, anti-apoptotic, and neuroprotective effects. The current study aimed to explore the antidepressant effects of baicalin and its possible molecular mechanisms affecting hippocampal neurogenesis via the regulation of the Wnt/β-catenin signaling pathway. A chronic mild unpredictable stress (CUMS) model of depression was used in the study. The CUMS-induced mice were treated with baicalin (50 and 100 mg/kg) for 21 days, orally, and the fluoxetine was used as positive control drug. The results indicated that baicalin alleviated CUMS-induced depression-like behaviour, and improved the nerve cells' survival of the hippocampal dentate gyrus (DG) in CUMS-induced depression of model mice and increased Ki-67- and doublecortin (DCX)-positive cells to restore CUMS-induced suppression of hippocampal neurogenesis. The related proteins in the Wnt/β-catenin signaling pathway, which declined in the CUMS-induced depression model of mice, were upregulated after baicalin treatment, including Wingless3a (Wnt3a), dishevelled2 (DVL2), and β-catenin. Further study found that the phosphorylation rate of glycogen synthase kinase-3β (GSK3β) and β-catenin nuclear translocation increased, as the levels of the β-catenin target genes cyclinD1, c-myc, NeuroD1, and Ngn2 upregulated after baicalin treatment. In conclusion, these findings suggest that baicalin may promote hippocampal neurogenesis, thereby exerting the antidepressant effect via regulation of the Wnt/β-catenin signaling pathway.

Promoting effects of MiR-135b on human multiple myeloma cells via regulation of the Wnt/β-catenin/Versican signaling pathway

MicroRNA (MiR)-135b and its mediated Wnt/β-catenin signaling pathway are involved in human malignancies. However, their roles in multiple myeloma (MM) remained poorly understood. Our study aimed to uncover their roles in MM. MiR-135b and Versican expressions were measured using quantitative real-time polymerase chain reaction (qRT-PCR). MM cell proliferation, apoptosis, migration and invasion were detected by cell counting kit-8 (CCK-8) assay, flow cytometry, wound healing assay and transwell assay, respectively. Relative expression of Wnt/β-catenin signaling pathway-related protein was quantified by Western blot. MiR-135b was upregulated in the serum of MM patients, and miR-135b upregulation promoted MM cell proliferation, migration and invasion but suppressed apoptosis. Also, miR-135b upregulation promoted activation of Wnt/β-catenin signaling pathway. However, downregulation of miR-135b caused an opposite effect. After incubating cells with miR-135b inhibitor and Wnt/β-catenin signaling pathway agonist Lithium chloride (LiCl), which reversed the effects of downregulating miR-135b. Versican is the downstream effector of the Wnt/β-catenin signaling pathway, and its silencing reversed the effects of LiCl on MM cells. In conclusion, miR-135b and its mediated Wnt/β-catenin signaling pathway promoted proliferation, migration and invasion but suppressed apoptosis of MM cells through regulating Versican, providing a possible treatment for MM.

Phosphofructokinase-1 Inhibition Promotes Neuronal Differentiation of Neural Stem Cells and Functional Recovery After Stroke

Ischemic stroke is a major cause of long-term disability. Neuronal differentiation of neural stem cells (NSCs) is crucial for brain repair after stroke. However, the underlying mechanisms remain unclear. Here, the role and potential mechanisms of phosphofructokinase-1 (PFK-1), the rate-limiting enzyme of glycolysis, was investigated in stroke using middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation models. We found that stroke increased the PFK-1 expression of NSCs. However, PFK-1 inhibition promoted neuronal differentiation of NSCs and facilitated the dendritic maturation of newborn neurons in vitro and in vivo. Moreover, PFK-1 inhibition also improved the spatial memory performance of MCAO rats. Additionally, we proved that the effect of PFK-1 inhibition above might be achieved by promoting β-catenin nuclear translocation and activating its downstream signaling, independent of Wnt signaling. Thus, these observations reveal a critical role of PFK-1 in stroke, which may provide a novel target for regenerative repair after stroke.

Lithium alleviates blood-brain barrier breakdown after cerebral ischemia and reperfusion by upregulating endothelial Wnt/β-catenin signaling in mice

Although upregulation of endothelial Wnt/β-catenin signaling may be used to treat blood-brain barrier (BBB) breakdown caused by cerebral ischemia/reperfusion injury, no agents based on this mechanism are available clinically. Lithium, a medication used for treating bipolar mood disorders, upregulates Wnt/β-catenin signaling, but whether lithium alleviates BBB breakdown after ischemic stroke by upregulating endothelial Wnt/β-catenin signaling is unclear. Here, we evaluated the BBB-protective effect of lithium in adult mice with 1-h middle cerebral artery occlusion and 48-h reperfusion (MCAO/R) by determining neurological outcomes, BBB function and related molecular components. Furthermore, we assessed the effect and dependence of lithium on Wnt/β-catenin signaling in brain microvascular endothelial cells in cell culture and in mice with conditional endothelial knockout of Wnt7 co-receptor Gpr124. Our data show that lithium treatment (3 mmol/kg) significantly decreased infarct volume (34.1 ± 1.8% versus 58.3 ± 2.8% in vehicle controls, P < 0.0001) and improved neurological outcomes of mice following MCAO/R. Importantly, lithium significantly increased BBB integrity shown by reduction of Evans blue leakage (by 45.7%, P = 0.0064) and blood IgG extravasation (by 65.8%, P < 0.0001) into infarcted brain tissue. Mechanistically, lithium upregulated the activity of endothelial Wnt/β-catenin signaling in vivo and in vitro, increased the protein levels of tight junctions (Claudin-5 and ZO-1), and reduced MMP-9 expression. Furthermore, the protective effect of lithium on cerebral damage and BBB integrity was abolished in endothelial Gpr124 knockout mice, indicating the protection of lithium on BBB was mainly dependent on the Gpr124-mediated endothelial Wnt/β-catenin signaling. Taken together, our findings indicate that lithium may serve as a therapeutic candidate for treating the BBB breakdown in the early stage of ischemic stroke following reperfusion therapy.

Curcumin promotes neurogenesis of hippocampal dentate gyrus via Wnt/β-catenin signal pathway following cerebral ischemia in mice

OBJECTIVES

To investigate whether curcumin promotes hippocampal neurogenesis in the cerebral ischemia (CI) mice via Wnt/β-catenin signaling pathway.

METHODS

Male C57BL/6 mice were randomly divided into groups: sham operation group (Sham), cerebral ischemic group (CI), curcumin treatment group (50, 100 mg/kg/d, i.p.) and curcumin (100 mg/kg/d) + DKK1 (a blocker of Wnt receptor, 200 ng/d, icv) group. CI was induced by bilateral common carotid arteries occlusion (BCCAO) for 20 min. The Morris water maze test was conducted to detect spatial learning and memory. Immunofluorescence staining was used to examine the proliferation and differentiation of immature neurons in the hippocampal dentate gyrus. The proteins involved in neurogenesis and Wnt signaling pathway were examined using Western blot assay.

RESULTS

Curcumin significantly alleviated cognitive deficits induced by CI. Curcumin dose-dependently increased the proliferation of neural stem cells and promoted the differentiation and maturation of newly generated neural cells into neurons. Curcumin also increased the expression of proteins involved in neurogenesis (including Ngn2, Pax6 and NeuroD 1) and the Wnt/β-catenin signaling pathway. Moreover, the forenamed effects of curcumin were abolished by pretreatment with DKK1, a blocker of Wnt receptor.

CONCLUSION

Curcumin promotes hippocampal neurogenesis by activating Wnt/β-catenin signaling pathway to ameliorate cognitive deficits after acute CI.

Lipid Emulsion Improves Functional Recovery in an Animal Model of Stroke

Stroke is a life-threatening condition that leads to the death of many people around the world. Reperfusion injury after ischemic stroke is a recurrent problem associated with various surgical procedures that involve the removal of blockages in the brain arteries. Lipid emulsion was recently shown to attenuate ischemic reperfusion injury in the heart and to protect the brain from excitotoxicity. However, investigations on the protective mechanisms of lipid emulsion against ischemia in the brain are still lacking. This study aimed to determine the neuroprotective effects of lipid emulsion in an in vivo rat model of ischemic reperfusion injury through middle cerebral artery occlusion (MCAO). Under sodium pentobarbital anesthesia, rats were subjected to MCAO surgery and were administered with lipid emulsion through intra-arterial injection during reperfusion. The experimental animals were assessed for neurological deficit wherein the brains were extracted at 24 h after reperfusion for triphenyltetrazolium chloride staining, immunoblotting and qPCR. Neuroprotection was found to be dosage-dependent and the rats treated with 20% lipid emulsion had significantly decreased infarction volumes and lower Bederson scores. Phosphorylation of Akt and glycogen synthase kinase 3-β (GSK3-β) were increased in the 20% lipid-emulsion treated group. The Wnt-associated signals showed a marked increase with a concomitant decrease in signals of inflammatory markers in the group treated with 20% lipid emulsion. The protective effects of lipid emulsion and survival-related expression of genes such as Akt, GSK-3β, Wnt1 and β-catenin were reversed by the intra-peritoneal administration of XAV939 through the inhibition of the Wnt/β-catenin signaling pathway. These results suggest that lipid emulsion has neuroprotective effects against ischemic reperfusion injury in the brain through the modulation of the Wnt signaling pathway and may provide potential insights for the development of therapeutic targets.

Vascular protection and regenerative effects of intranasal DL-3-N-butylphthalide treatment after ischaemic stroke in mice

Objective

To investigate the effects of DL-3-N-butylphthalide (NBP) via intranasal delivery after ischaemic stroke in mice.

Methods

C57BL/6 mice were divided into three groups: sham, stroke with vehicle and stroke with NBP treatment. Ischaemic stroke was induced by permanent ligation of right middle cerebral artery with 7 min common carotid artery occlusion. NBP (100 mg/kg) or vehicle was intranasally administered at 1 hour after stroke and repeated once a day until sacrifice. Bromodeoxyuridine (BrdU) (50 mg/kg/day) was given from the third day until sacrifice. Sensorimotor function was tested during 1–21 days after stroke. Local cerebral blood flow in the ischaemic and peri-infarct regions was measured using laser Doppler flowmetry before, during and 3 days after ischaemia. Expressions of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase as well as regenerative marker BrdU in the peri-infarct region were analysed by western blotting and immunohistochemical methods.

Results

Compared with the vehicle group, NBP treatment significantly increased the VEGF expression in the poststroke brain. Stroke mice that received NBP showed significantly less vascular damage after stroke and more new neurons and blood vessels in the peri-infarct region at 21 days after stroke. In the adhesive removal test, the sensorimotor function of stroke mice treated with NBP performed significantly better at 1, 3 and 7 days after stroke compared with vehicle controls.

Conclusion

Daily intranasal NBP treatment provides protective and neurogenic/angiogenic effects in the poststroke brain, accompanied with functional improvements after a focal ischaemic stroke in mice.

Wnt Pathway: An Emerging Player in Vascular and Traumatic Mediated Brain Injuries

The Wnt pathway, which comprises the canonical and non-canonical pathways, is an evolutionarily conserved mechanism that regulates crucial biological aspects throughout the development and adulthood. Emergence and patterning of the nervous and vascular systems are intimately coordinated, a process in which Wnt pathway plays particularly important roles. In the brain, Wnt ligands activate a cell-specific surface receptor complex to induce intracellular signaling cascades regulating neurogenesis, synaptogenesis, neuronal plasticity, synaptic plasticity, angiogenesis, vascular stabilization, and inflammation. The Wnt pathway is tightly regulated in the adult brain to maintain neurovascular functions. Historically, research in neuroscience has emphasized essentially on investigating the pathway in neurodegenerative disorders. Nonetheless, emerging findings have demonstrated that the pathway is deregulated in vascular- and traumatic-mediated brain injuries. These findings are suggesting that the pathway constitutes a promising target for the development of novel therapeutic protective and restorative interventions. Yet, targeting a complex multifunctional signal transduction pathway remains a major challenge. The review aims to summarize the current knowledge regarding the implication of Wnt pathway in the pathobiology of ischemic and hemorrhagic stroke, as well as traumatic brain injury (TBI). Furthermore, the review will present the strategies used so far to manipulate the pathway for therapeutic purposes as to highlight potential future directions.

XQ-1H regulates Wnt/GSK3β/β-catenin pathway and ameliorates the integrity of blood brain barrier in mice with acute ischemic stroke

10-O-(N, N-dimethylaminoethyl) ginkgolide B methanesulfonate (XQ-1H), a novel analog of ginkgolide B, has been preliminarily recognized to show bioactivities against ischemia-induced injury. However, the underlying mechanism still remains to be fully elucidated. The aim of this study was to investigate the effect of XQ-1H against cerebral ischemia/reperfusion injury (CIRI) from the perspective of blood brain barrier (BBB) protection, and explore whether the underlying mechanism is associated with Wnt/GSK3β/β-catenin signaling pathway activation. The therapeutic effects of XQ-1H were evaluated in mice subjected to middle cerebral artery occlusion/reperfusion (MCAO/R) and in immortalized mouse cerebral endothelial cells (bEnd.3) challenged by oxygen and glucose deprivation/reoxygenation (OGD/R). Results showed that treatment with XQ-1H improved neurological behavior, reduced brain infarction volume, diminished edema, and attenuated the disruption of BBB in vivo. In vitro, XQ-1H increased cell viability and maintained the barrier function of bEnd.3 monolayer after OGD/R. Moreover, the protection of XQ-1H was accompanied with activation of Wnt/GSK3β/β-catenin pathway and upregulation of tight junction proteins. Notably, the protection of XQ-1H was abolished by Wnt/GSK3β/β-catenin inhibitor XAV939 or β-catenin siRNA, indicating XQ-1H exerted protection in a Wnt/GSK3β/β-catenin dependent profile. In summary, XQ-1H attenuated brain injury and maintained BBB integrity after CIRI, and the possible underlying mechanism may be related to the activation of Wnt/GSK3β/β-catenin pathway and upregulation of tight junction proteins.

Nrf2/Wnt resilience orchestrates rejuvenation of glia-neuron dialogue in Parkinson's disease

Oxidative stress and inflammation have long been recognized to contribute to Parkinson's disease (PD), a common movement disorder characterized by the selective loss of midbrain dopaminergic neurons (mDAn) of the substantia nigra pars compacta (SNpc). The causes and mechanisms still remain elusive, but a complex interplay between several genes and a number of interconnected environmental factors, are chiefly involved in mDAn demise, as they intersect the key cellular functions affected in PD, such as the inflammatory response, mitochondrial, lysosomal, proteosomal and autophagic functions. Nuclear factor erythroid 2 -like 2 (NFE2L2/Nrf2), the master regulator of cellular defense against oxidative stress and inflammation, and Wingless (Wnt)/β-catenin signaling cascade, a vital pathway for mDAn neurogenesis and neuroprotection, emerge as critical intertwinned actors in mDAn physiopathology, as a decline of an Nrf2/Wnt/β-catenin prosurvival axis with age underlying PD mutations and a variety of noxious environmental exposures drive PD neurodegeneration. Unexpectedly, astrocytes, the so-called "star-shaped" cells, harbouring an arsenal of "beneficial" and "harmful" molecules represent the turning point in the physiopathological and therapeutical scenario of PD. Fascinatingly, "astrocyte's fil rouge" brings back to Nrf2/Wnt resilience, as boosting the Nrf2/Wnt resilience program rejuvenates astrocytes, in turn (i) mitigating nigrostriatal degeneration of aged mice, (ii) reactivating neural stem progenitor cell proliferation and neuron differentiation in the brain and (iii) promoting a beneficial immunomodulation via bidirectional communication with mDAns. Then, through resilience of Nrf2/Wnt/β-catenin anti-ageing, prosurvival and proregenerative molecular programs, it seems possible to boost the inherent endogenous self-repair mechanisms. Here, the cellular and molecular aspects as well as the therapeutical options for rejuvenating glia-neuron dialogue will be discussed together with major glial-derived mechanisms and therapies that will be fundamental to the identification of novel diagnostic tools and treatments for neurodegenerative diseases (NDs), to fight ageing and nigrostriatal DAergic degeneration and promote functional recovery.

XQ-1H attenuates ischemic injury in PC12 cells via Wnt/β-catenin signaling though inhibition of apoptosis and promotion of proliferation

10-O-(N,N-dimethylaminoethyl)-ginkgolide B methanesulfonate (XQ-1H) is a new derivative of ginkgolide B and has previously been proven to exert neuroprotective effects on ischemic injury. However, it is not clear whether XQ-1H affects the cell survival and proliferation in oxygen-glucose deprivation/reoxygenation (OGD/R) damaged PC12 cells. Our results showed that OGD/R improved cell viability after 24 hr of posttreatment with XQ-1H (10 or 5 μM), inhibiting cell injury and apoptosis by upregulating the expression of brain-derived neurotrophic factor, nerve growth factor, and antiapoptotic B-cell lymphoma-extra large, while reducing proapoptotic cleaved caspase-3 protein. By introducing the Wnt/β-catenin signaling inhibitor XAV-939 and 5-bromo-2'-deoxyuridine staining, it was proved that XQ-1H promoted the proliferation of PC12 cells in a Wnt-signal-dependent manner via inhibiting the activation of glycogen synthase kinase-3β after phosphatidylinositol 3-kinase/protein kinase B signal activation, thereby activating Wnt1, β-catenin, and the expression of downstream neurogenic differentiation 1 and cyclin D1, which was comparable to Wnt/β-catenin signaling agonist 4,6-disubstituted pyrrolopyrimidine. We conclude that XQ-1H, after OGD/R damage to PC12 cells, may limit cell apoptosis in a Wnt/β-catenin signal-dependent manner, promoting cell proliferation and survival.

Effect of Wnt signaling pathway on neurogenesis after cerebral ischemia and its therapeutic potential

Neurogenesis process in the chronic phase of ischemic stroke has become the focus of research on stroke treatment recently, mainly through the activation of related pathways to increase the differentiation of neural stem cells (NSCs) in the brain sub-ventricular zone (SVZ) and subgranular zone (SGZ) of hippocampal dentate gyrus (DG) areas into neurons, promoting neurogenesis. While there is still debate about the longevity of active adult neurogenesis in humans, the SVZ and SGZ have the capacity to upregulate neurogenesis in response to cerebral ischemia, which opens discussion about potential treatment strategies to harness this neuronal regenerative response. Wnt signaling pathway is one of the most important approaches potentially targeting on neurogenesis after cerebral ischemia, appropriate activation of which in NSCs may help to improve the sequelae of cerebral ischemia. Various therapeutic approaches are explored on preclinical stage to target endogenous neurogenesis induced by Wnt signaling after stroke onset. This article describes the composition of Wnt signaling pathway and the process of neurogenesis after cerebral ischemia, and emphatically introduces the recent studies on the mechanisms of this pathway for post-stroke neurogenesis and the therapeutic possibility of activating the pathway to improve neurogenesis after stroke.

Glia and Neural Stem and Progenitor Cells of the Healthy and Ischemic Brain: The Workplace for the Wnt Signaling Pathway

Wnt signaling plays an important role in the self-renewal, fate-commitment and survival of the neural stem/progenitor cells (NS/PCs) of the adult central nervous system (CNS). Ischemic stroke impairs the proper functioning of the CNS and, therefore, active Wnt signaling may prevent, ameliorate, or even reverse the negative effects of ischemic brain injury. In this review, we provide the current knowledge of Wnt signaling in the adult CNS, its status in diverse cell types, and the Wnt pathway’s impact on the properties of NS/PCs and glial cells in the context of ischemic injury. Finally, we summarize promising strategies that might be considered for stroke therapy, and we outline possible future directions of the field.

Modulation of Stem Cells as Therapeutics for Severe Mental Disorders and Cognitive Impairments

Severe mental illnesses (SMI) such as schizophrenia and bipolar disorder affect 2-4% of the world population. Current medications and diagnostic methods for mental illnesses are not satisfying. In animal studies, stem cell therapy is promising for some neuropsychiatric disorders and cognitive/social deficits, not only treating during development (targeting modulation and balancing) but also following neurodegeneration (cell replacement and regenerating support). We believe that novel interventions such as modulation of particular cell populations to develop cell-based treatment can improve cognitive and social functions in SMI. With pathological synaptic/myelin damage, oligodendrocytes seem to play a role. In this review, we have summarized oligodendrogenesis mechanisms and some related calcium signals in neural cells and stem/progenitor cells. The related benefits from endogenous stem/progenitor cells within the brain and exogenous stem cells, including multipotent mesenchymal-derived stromal cells (MSC), fetal neural stem cells (NSC), pluripotent stem cells (PSC), and differentiated progenitors, are discussed. These also include stimulating mechanisms of oligodendrocyte proliferation, maturation, and myelination, responsive to the regenerative effects by both endogenous stem cells and transplanted cells. Among the mechanisms, calcium signaling regulates the neuronal/glial progenitor cell (NPC/GPC)/oligodendrocyte precursor cell (OPC) proliferation, migration, and differentiation, dendrite development, and synaptic plasticity, which are involved in many neuropsychiatric diseases in human. On the basis of numerous protein annotation and protein-protein interaction databases, a total of 119 calcium-dependent/activated proteins that are related to neuropsychiatry in human are summarized in this investigation. One of the advanced methods, the calcium/cation-channel-optogenetics-based stimulation of stem cells and transplanted cells, can take advantage of calcium signaling regulations. Intranasal-to-brain delivery of drugs and stem cells or local delivery with the guidance of brain imaging techniques may provide a unique new approach for treating psychiatric disorders. It is also expected that preconditioning stem cell therapy following precise brain imaging as pathological confirmation has high potential if translated to cell clinic use. Generally, modulable cell transplantation followed by stimulations should provide paracrine protection, synaptic modulation, and myelin repair for the brain in SMI.

Propofol Attenuates α-Synuclein Aggregation and Neuronal Damage in a Mouse Model of Ischemic Stroke

α-Synuclein is a soluble monomer abundant in the central nervous system. Aggregates of α-synuclein, consisting of higher-level oligomers and insoluble fibrils, have been observed in many chronic neurological diseases and are implicated in neurotoxicity and neurodegeneration. α-Synuclein has recently been shown to aggregate following acute ischemic stroke, exacerbating neuronal damage. Propofol is an intravenous anesthetic that is commonly used during intravascular embolectomy following acute ischemic stroke. While propofol has demonstrated neuroprotective properties following brain injury, the mechanism of protection in the setting of ischemic stroke is unclear. In this study, propofol administration significantly reduced the neurotoxic aggregation of α-synuclein, decreased the infarct area, and attenuated the neurological deficits after ischemic stroke in a mouse model. We then demonstrated that the propofol-induced reduction of α-synuclein aggregation was associated with increased mammalian target of rapamycin/ribosomal protein S6 kinase beta-1 signaling pathway activity and reduction of the excessive autophagy occurring after acute ischemic stroke.

Treadmill exercise promotes neurogenesis and myelin repair via upregulating Wnt/β‑catenin signaling pathways in the juvenile brain following focal cerebral ischemia/reperfusion

Physical exercise has a neuroprotective effect and is an important treatment after ischemic stroke. Promoting neurogenesis and myelin repair in the penumbra is an important method for the treatment of ischemic stroke. However, the role and potential mechanism of exercise in neurogenesis and myelin repair still needs to be clarified. The goal of the present study was to ascertain the possible effect of treadmill training on the neuroprotective signaling pathway in juvenile rats after ischemic stroke. The model of middle cerebral artery occlusion (MCAO) in juvenile rats was established and then the rats were randomly divided into 9 groups. XAV939 (an inhibitor of the Wnt/β‑catenin pathway) was used to confirm the effects of the Wnt/β‑catenin signaling pathway on exercise‑mediated neurogenesis and myelin repair. Neurological deficits were detected by modified neurological severity score, the injury of brain tissue and the morphology of neurons was detected by hematoxylin‑eosin staining and Nissl staining, and the infarct volume was detected by 2,3,5‑triphenyl tetrazolium chloride staining. The changes in myelin were observed by Luxol fast blue staining. The neuron ultrastructure was observed by transmission electron microscopy. Immunofluorescence and western blots analyzed the molecular mechanisms. The results showed that treadmill exercise improved neurogenesis, enhanced myelin repair, promoted neurological function recovery and reduced infarct volume. These were the results of the upregulation of Wnt3a and nucleus β‑catenin, brain‑derived neurotrophic factor (BDNF) and myelin basic protein (MBP). In addition, XAV939 inhibited treadmill exercise‑induced neurogenesis and myelin repair, which was consistent with the downregulation of Wnt3a, nucleus β‑catenin, BDNF and MBP expression, and the deterioration of neurological function. In summary, treadmill exercise promotes neurogenesis and myelin repair by upregulating the Wnt/β‑catenin signaling pathway, to improve the neurological deficit caused by focal cerebral ischemia/reperfusion.

WNT3A Promotes Neuronal Regeneration upon Traumatic Brain Injury

The treatment of traumatic brain injury (TBI) remains a challenge due to limited knowledge about the mechanisms underlying neuronal regeneration. This current study compared the expression of WNT genes during regeneration of injured cortical neurons. Recombinant WNT3A showed positive effect in promoting neuronal regeneration via in vitro, ex vivo, and in vivo TBI models. Intranasal administration of WNT3A protein to TBI mice increased the number of NeuN⁺ neurons without affecting GFAP⁺ glial cells, compared to control mice, as well as retained motor function based on functional behavior analysis. Our findings demonstrated that WNT3A, 8A, 9B, and 10A promote regeneration of injured cortical neurons. Among these WNTs, WNT3A showed the most promising regenerative potential in vivo, ex vivo, and in vitro.

Zinc promotes cell apoptosis via activating the Wnt-3a/β-catenin signaling pathway in osteosarcoma

BACKGROUND

The zinc content in the blood and tumor tissues of patients with osteosarcoma and the underlying regulation and molecular mechanism of zinc have not been reported.

METHODS AND RESULTS

This study showed that the zinc content in the blood and tumor tissues of patients with osteosarcoma significantly reduced. CCK-8 and Transwell chamber assays revealed that zinc treatment significantly inhibited the proliferation and invasion abilities of osteosarcoma cells. Western blot analysis indicated that the expression levels of caspase-3 and caspase-9 were significantly increased, suggesting that zinc inhibited the growth and promoted the apoptosis of osteosarcoma cells. In addition, the expression levels of Wnt-3a and β-catenin, the marker proteins of the Wnt/β-catenin signaling pathways, were significantly increased in osteosarcoma cells after zinc intervention, which demonstrated that the pathway was clearly activated. However, the effect of zinc on the apoptosis, proliferation, and invasion abilities of osteosarcoma cells was reversed when the Wnt/β-catenin signaling pathways was inhibited by XAV939 (Wnt antagonist) treatment.

CONCLUSIONS

This study is the first to report the changes in zinc levels in the blood and tumor tissues of patients with osteosarcoma and to preliminarily verify that zinc inhibits the proliferation and invasion and promote the apoptosis of osteosarcoma cells by inducing the Wnt/β-catenin signaling pathway, which ultimately inhibit cancer growth.

Cyclophilin D Contributes to Anesthesia Neurotoxicity in the Developing Brain

Anesthetic sevoflurane induces mitochondrial dysfunction, impairment of neurogenesis, and cognitive impairment in young mice, but the underlying mechanism remains to be determined. Cyclophilin D (CypD) is a modulatory factor for the mitochondrial permeability transition pore (mPTP). We, therefore, set out to evaluate the role of CypD in these sevoflurane-induced changes in vitro and in young mice. Wild-type (WT) and CypD knockout (KO) young (postnatal day 6, 7, and 8) mice received 3% sevoflurane 2 h daily and the neural progenitor cells (NPCs) harvested from the WT or CypD KO mice received 4.1% sevoflurane. We used immunohistochemistry and immunocytochemistry imaging, flow cytometry, Western blot, RT-PCR, co-immunoprecipitation, and Morris Water Maze to assess the interaction of sevoflurane and CypD on mitochondria function, neurogenesis, and cognition in vitro and in WT or CypD KO mice. We demonstrated that the sevoflurane anesthesia induced accumulation of CypD, mitochondrial dysfunction, impairment of neurogenesis, and cognitive impairment in WT mice or NPCs harvested from WT mice, but not in CypD KO mice or NPCs harvested from CypD KO mice. Furthermore, the sevoflurane anesthesia reduced the binding of CypD with Adenine nucleotide translocator, the other component of mPTP. These data suggest that the sevoflurane anesthesia might induce a CypD-dependent mitochondria dysfunction, impairment of neurogenesis, and cognitive impairment in young mice and NPCs.

Rosiglitazone ameliorates tissue plasminogen activator-induced brain hemorrhage after stroke

Objective

Delayed thrombolytic therapy with recombinant tissue plasminogen activator (tPA) may exacerbate blood‐brain barrier (BBB) breakdown after ischemic stroke and lead to catastrophic hemorrhagic transformation (HT). Rosiglitazone(RSG), a widely used antidiabetic drug that activates peroxisome proliferator‐activated receptor‐γ (PPAR‐γ), has been shown to protect against cerebral ischemia through promoting poststroke microglial polarization toward the beneficial anti‐inflammatory phenotype. However, whether RSG can alleviate HT after delayed tPA treatment remains unknown. In this study, we sort to examine the role of RSG on tPA‐induced HT after stroke.

Methods and results

We used the murine suture middle cerebral artery occlusion (MCAO) models of stroke followed by delayed administration of tPA (10 mg/kg, 2 hours after suture occlusion) to investigate the therapeutic potential of RSG against tPA‐induced HT. When RSG(6 mg/kg) was intraperitoneally administered 1 hour before MCAO in tPA‐treated MCAO mice, HT in the ischemic territory was significantly attenuated 1 day after stroke. In the tPA‐treated MCAO mice, we found RSG significantly mitigated BBB disruption and hemorrhage development compared to tPA‐alone‐treated stroke mice. Using flow cytometry and immunostaining, we confirmed that the expression of CD206 was significantly upregulated while the expression of iNOS was down‐regulated in microglia of the RSG‐treated mice. We further found that the expression of Arg‐1 was also upregulated in those tPA and RSG‐treated stroke mice and the protection against tPA‐induced HT and BBB disruption in these mice were abolished in the presence of PPAR‐γ antagonist GW9662 (4 mg/kg, 1 hour before dMCAO through intraperitoneal injection).

Conclusions

RSG treatment protects against BBB damage and ameliorates HT in delayed tPA‐treated stroke mice by activating PPAR‐γ and favoring microglial polarization toward anti‐inflammatory phenotype.

XQ-1H alleviates cerebral ischemia in mice through inhibition of apoptosis and promotion of neurogenesis in a Wnt/β-catenin signaling dependent way

AIMS

10-O-(N,N-dimethylaminoethyl)-ginkgolide B methanesulfonate (XQ-1H), a new derivative of ginkgolide B, has drawn great attention for its potent bioactivities against ischemia-induced injury. The purpose of this study was to further investigate the effect of XQ-1H against acute ischemic stroke by inducing middle cerebral artery occlusion/reperfusion (MCAO/R) injuries in mice.

MAIN METHODS

Treatment of XQ-1H (78 or 39 mg/kg, i.g., bid) 2 h after MCAO improved motor skills and ameliorated the severity of brain infarction and apoptosis seen in the mice by diminishing pathological changes and the activation of a pro-apoptotic protein Cleaved-Caspase-3, which in turn induced anti-apoptotic Bcl-xL. Through introducing Wnt/β-catenin signaling inhibitor XAV-939, XQ-1H was proven to intensively promoted neurogenesis in the peri-infarct cortex, subventricular area (SVZ) and the dentate gyrus (DG) subgranular area (SGZ) in a Wnt signal dependent way by compromising the activation of GSK3β, which in turn upregulated Wnt1, β-catenin, Neuro D1 and Cyclin D1, most possibly through the activation of PI3K/Akt signaling via the upregulation of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF).

KEY FINDINGS

We conclude that XQ-1H preserved the motor functions, limited apoptosis, and concomitantly promoted neurogenesis-related protein expression by Wnt signaling-dependently compromising GSK3β/Caspase-3 activity and enhancing the expression of Wnt1/β-catenin/Neuro D1/Cyclin D1 and Bcl-xL.

SIGNIFICANCE

This research may benefit the development of stroke therapeutics targeting neurogenesis through Wnt upregulation by XQ-1H.

Enhanced Neurogenesis and Collaterogenesis by Sodium Danshensu Treatment After Focal Cerebral Ischemia in Mice

Ischemic stroke remains a serious threat to human life. There are limited effective therapies for the treatment of stroke. We have previously demonstrated that angiogenesis and neurogenesis in the brain play an important role in functional recovery following ischemic stroke. Recent studies indicate that increased arteriogenesis and collateral circulation are determining factors for restoring reperfusion and outcomes of stroke patients. Danshensu, the Salvia miltiorrhiza root extract, is used in treatments of various human ischemic events in traditional Chinese medicine. Its therapeutic mechanism, however, is not well clarified. Due to its proposed effect on angiogenesis and arteriogenesis, we hypothesized that danshensu could benefit stroke recovery through stimulating neurogenesis and collaterogenesis in the post-ischemia brain. Focal ischemic stroke targeting the right sensorimotor cortex was induced in wild-type C57BL6 mice and transgenic mice expressing green fluorescent protein (GFP) to label smooth muscle cells of brain arteries. Sodium danshensu (SDS, 700 mg/kg) was administered intraperitoneally (i.p.) 10 min after stroke and once daily until animals were sacrificed. To label proliferating cells, 5-bromo-2′-deoxyuridine (BrdU; 50 mg/kg, i.p.) was administered, starting on day 3 after ischemia and continued once daily until sacrifice. At 14 days after stroke, SDS significantly increased the expression of vascular endothelial growth factor (VEGF), stromal-derived factor-1 (SDF-1), brain-derived neurotrophic factor (BDNF), and endothelial nitric oxide synthase (eNOS) in the peri-infarct region. SDS-treated animals showed increased number of doublecortin (DCX)-positive cells. Greater numbers of proliferating endothelial cells and smooth muscle cells were detected in SDS-treated mice 21 days after stroke in comparison with vehicle controls. The number of newly formed neurons labeled by NeuN and BrdU antibodies increased in SDS-treated mice 28 days after stroke. SDS significantly increased the newly formed arteries and the diameter of collateral arteries, leading to enhanced local cerebral blood flow recovery after stroke. These results suggest that systemic sodium danshensu treatment shows significant regenerative effects in the post-ischemic brain, which may benefit long-term functional recovery from ischemic stroke.

Priming of the Cells: Hypoxic Preconditioning for Stem Cell Therapy

Objective:

Stem cell-based therapies are promising in regenerative medicine for protecting and repairing damaged brain tissues after injury or in the context of chronic diseases. Hypoxia can induce physiological and pathological responses. A hypoxic insult might act as a double-edged sword, it induces cell death and brain damage, but on the other hand, sublethal hypoxia can trigger an adaptation response called hypoxic preconditioning or hypoxic tolerance that is of immense importance for the survival of cells and tissues.

Data Sources:

This review was based on articles published in PubMed databases up to August 16, 2017, with the following keywords: “stem cells,” “hypoxic preconditioning,” “ischemic preconditioning,” and “cell transplantation.”

Study Selection:

Original articles and critical reviews on the topics were selected.

Results:

Hypoxic preconditioning has been investigated as a primary endogenous protective mechanism and possible treatment against ischemic injuries. Many cellular and molecular mechanisms underlying the protective effects of hypoxic preconditioning have been identified.

Conclusions:

In cell transplantation therapy, hypoxic pretreatment of stem cells and neural progenitors markedly increases the survival and regenerative capabilities of these cells in the host environment, leading to enhanced therapeutic effects in various disease models. Regenerative treatments can mobilize endogenous stem cells for neurogenesis and angiogenesis in the adult brain. Furthermore, transplantation of stem cells/neural progenitors achieves therapeutic benefits via cell replacement and/or increased trophic support. Combinatorial approaches of cell-based therapy with additional strategies such as neuroprotective protocols, anti-inflammatory treatment, and rehabilitation therapy can significantly improve therapeutic benefits. In this review, we will discuss the recent progress regarding cell types and applications in regenerative medicine as well as future applications.