Targeted Delivery of Intranasally Administered Cyclovirobuxine D Liposomes to Brain for Treatment Cerebral Ischemia-Reperfusion Injury via Anti-oxidative Stress and Activating Autophagy

The lack of effective therapy mandates development of treatment for cerebral ischemia-reperfusion injury (CIRI. The previous study suggested that Cyclovirobuxine D (CVBD) encapsulated in Angiopep-conjugated Polysorbate 80-Coated Liposomes showed a better brain targeting by intranasal administration. Therefore, this study focused on the protection and mechanism of CVBD brain-targeted liposomes in treating CIRI. In order to evaluate these, the CIRI rat model was induced by middle cerebral artery occlusion (MCAO)-reperfusion. Pharmacological evaluation was assessed in vivo by general indexs, neurobehavioral scores, triphenyl tetrazolium chloride (TTC) staining, histopathological staining (HE staining and Nissl staining), small animal magnetic resonance imaging, biochemical assay and Western blot. The results show that CVBD liposomes alleviated pathological damage of brain. Futhermore, the protective effect of CVBD liposomes on OGD/R-injured HT22 cell was investigated by cell fusion degree, cell proliferation curve and cell viability. OGD/R-injured HT22 cell was infected by mRFP-GFP-LC3 adenovirus. The autophagosome and autophagy flow were observed by laser confocal microscopy, and autophagy-related protein expressions (LC3, p62 and Beclin 1) were analyzed by Western blot. Meanwhile, the classic autophagy inhibitor, chloroquine, was used to explore the autophagy-regulated mechanism of CVBD brain-targeted liposomes in treating CIRI. In cell model of oxygen and glucose deprivation/re-oxygenation, CVBD liposomes increased cell viability and decreased ROS level. CVBD liposomes improved oxidative stress protein expressions and activated autophagy in vitro. Furthermore, CVBD liposomes reversed the decrease of cell viability, increase of ROS level, and reduction of protein expressions associated to anti-oxidative stress and autophagy induced by chloroquine. Collectively, CVBD liposomes inhibited CIRI via regulating oxidative stress and enhancing autophagy level in vivo and in vitro, showing a great potential in treating CIRI in clinic.

MicroRNA-21-5p Reduces Hypoxia/Reoxygenation-Induced Neuronal Cell Damage through Negative Regulation of CPEB3

Objectives. To explore the role of microRNA-21-5p (miR-21-5p) in hypoxia/reoxygenation- (H/R-) induced HT22 cell damage. Methods. The hypoxia/reoxygenation (H/R) model was established in mouse neuronal cells HT22. Cell Counting Kit-8 (CCK-8) and qRT-PCR were used to determine the effects of H/R treatment on cell viability and miR-21-5p expression. HT22 cells were transfected with miR-21-5p mimic or negative control (NC) followed by the induction of H/R; cell viability, apoptosis, and SOD, MDA, and LDH activities were detected. Besides, the apoptosis-related proteins including BAX, BCL2, cleaved caspase-3, and caspase-3 as well as proteins of EGFR/PI3K/AKT signaling pathways were measured by Western blot. To verify the target relation between cytoplasmic polyadenylation element binding protein 3 (CPEB3) and miR-21-5p, luciferase reporter gene experiment was performed. After cotransfection with miR-21-5p mimic and CPEB3 plasmids, the reversal effects of CPEB3 on miR-21-5p in H/R damage were studied. Results. H/R treatment could significantly reduce the cell viability ( P < 0.05 ) and miR-21-5p levels ( P < 0.05 ) in HT22 cells. After overexpressing miR-21-5p, cell viability was increased ( P < 0.05 ) under H/R treatment, and the apoptosis rate and the levels of apoptosis-related proteins were suppressed (all P < 0.05 ). Furthermore, SOD activity was increased ( P < 0.05 ), while MDA and LDH activity was decreased (both P < 0.05 ). Besides, miR-21-5p could restore the activation of the EGFR/PI3K/AKT signaling pathway inhibited by H/R treatment (all P < 0.05 ). The luciferase reporter gene experiment verified that CPEB3 is the target of miR-21-5p ( P < 0.05 ). When coexpressing miR-21-5p mimic and CPEB3 in the cells, the protective effects of miR-21-5p under H/R were reversed (all P < 0.05 ), and the activation of the EGFR/PI3K/AKT pathway was also inhibited (all P < 0.05 ). Conclusion. This study showed that miR-21-5p may regulate the EGFR/PI3K/AKT signaling pathway by targeting CPEB3 to reduce H/R-induced cell damage and apoptosis.

Apoptosis Inducible Factor P53 Decrease Glutamate-Associated Damage via Inhibiting Ferroptosis

BACKGROUND: Ferroptosis, a pattern of programmed cell death decided by iron-associated lipid peroxidation, however, its role of p53-mediated xCT pathway in HT22 cell death remains obscure. Herein, this study is to investigate the potential mechanism of the effect of p53-mediated xCT pathway in HT22 cell lines in an iron-relevant mode. METHODS: The viability of HT22 cells were detected by Cell Counting Kit-8(CCK-8) and PI/Hoechst fluorescence double staining. The protein expression levels of p53 and xCT were determined by western boltting. DHE fluorescence staining technique supervised the intracellular reactive oxygen species (ROS), and intracellular lipid oxidant situation was confirmed by BODIPY 581/591 C11 lipid peroxidation sensor. Intracellular ferrous ions were monitored with FeRhoNox™-1 fluoresceent probe. RESULTS: The protein expression levels of p53 was obviously enhanced by tenovin-1 exposure. Accompanied with the upregulation of p53 protein, cell death was decreased significantly because of glutamate and erastin exposure with 8h, and p53-mediated xCT pathway was activated. Intracelluar ROS levels, lipid oxidant situations and ferrous ions were remarkably restricted from Glutamate-p53 groups in comparison with glutamate groups. CONCLUSIONS: Overall, P53-mediated xCT pathway could decrease the glutamate-associated neurotoxicity, which may be relevant to the inhibition of ferroptosis.

Functional Network of the Long Non-coding RNA Growth Arrest-Specific Transcript 5 and Its Interacting Proteins in Senescence

Increasing studies show that long non-coding RNAs (lncRNAs) play essential roles in various fundamental biological processes. Long non-coding RNA growth arrest-specific transcript 5 (GAS5) showed differential expressions between young and old mouse brains in our previous RNA-Seq data, suggesting its potential role in senescence and brain aging. Examination using quantitative reverse transcription-polymerase chain reaction revealed that GAS5 had a significantly higher expression level in the old mouse brain hippocampus region than the young one. Cellular fractionation using hippocampus-derived HT22 cell line confirmed its nucleoplasm and cytoplasm subcellular localization. Overexpression or knockdown of GAS5 in HT22 cell line revealed that GAS5 inhibits cell cycle progression and promotes cell apoptosis. RNA-Seq analysis of GAS5-knockdown HT22 cells identified differentially expressed genes related to cell proliferation (e.g., DNA replication and nucleosome assembly biological processes). RNA pull-down assay using mouse brain hippocampus tissues showed that potential GAS5 interacting proteins could be enriched into several Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and some of them are involved in senescence-associated diseases such as Parkinson’s and Alzheimer’s diseases. These results contribute to understand better the underlying functional network of GAS5 and its interacting proteins in senescence at brain tissue and brain-derived cell line levels. Our study may also provide a reference for developing diagnostic and clinic biomarkers of GAS5 in senescence and brain aging.

Janus Kinase Inhibition Ameliorates Cerebral Ischemic Injury and Neuroinflammation through Reducing NLRP3 Inflammasome Activation via JAK2/STAT3 Pathway Inhibition

BackgroundEvidence shows that inflammatory responses play multiphasic roles in stroke pathogenesis. Ruxolitinib (Rux), a selective oral JAK 1/2 inhibitor, is efficacious in COVID-19 by reducing inflammation via the JAK2/STAT3 pathway. MethodsHere, we investigated whether JAK2 inhibition has neuroprotective effects against ischemic stroke (IS) in MCAO mice in vivo and in vitro oxygen-glucose deprivation/reoxygenation (OGD/R) model, and explored the potential molecular mechanisms. Rux was applied to MCAO mice. Immunofluorescence staining, RT-qPCR, and western blots were used to measure the expression of NLRP3 inflammation components and proinflammatory cytokines as well as JAK2/STAT3 pathway. Local STAT3 deficiency in brain tissue was established to investigate the interplay between NLRP3 and STAT3 signaling.ResultsRux treatment obviously improved neurological scores, decreased the infarct size and ameliorated cerebral edema 3 days after stroke. In addition, immunofluorescence staining and western blots showed that Rux application inhibited the expression of NLRP3 inflammasome components, proteins related to the NLRP3 inflammasome and phosphorylated STAT3 (p-STAT3) in neurons. Furthermore, Rux administration inhibited the expression of proinflammatory cytokines, including TNF-α, IFN-γ, HMBG1, IL-1β, IL-2, and IL-6 in middle cerebral artery occlusion (MCAO) model mice, suggesting that Rux may alleviate IS injury by inhibiting proinflammatory reactions via JAK2/STAT3 signaling pathway regulation. Local STAT3 deficiency decreased histone H3 and H4 acetylation on the NLRP3 promoter and the NLRP3 inflammasome component expression, indicating that the NLRP3 inflammasome may be directly regulated by STAT3 signaling. Finally, the effect of Rux on the NLRP3 inflammasome was further assessed in a HT22 cell OGD/R model in vitro. Rux application markedly suppressed lipopolysaccharide (LPS)-induced NLRP3 inflammasome secretion and JAK2/STAT3 pathway activation in vitro the in OGD/R HT22 cell model.ConclusionJAK2 inhibition by Rux in MCAO mice decreased STAT3 phosphorylation, thus inhibiting downstream proinflammatory cytokines and H3 and H4 acetylation on the NLRP3 promoter, resulting in downregulation of NLRP3 inflammasome component expression.

Comprehensive epigenetic analysis of m6A modification in the hippocampal injury of diabetic rats

Aim: To study RNA N6-methyladenosine (m6A) modification in the diabetic hippocampus. Methods: Behavioral tests and staining were performed to evaluate the damage to the diabetic hippocampus in model rats. Western blotting was performed to investigate the expression of methylation-related enzymes, and flow cytometry was used to demonstrate HT22 cell apoptosis. M6A and RNA sequencing analyses were conducted to profile m6A-tagged transcripts in the diabetic hippocampus. Results: The rat models of diabetes mellitus suffered from cognitive disorders and hippocampal neuron damage. High glucose levels altered the expression of methylation-related enzymes. A total of 4890 differentially methylated m6A peaks and 63 differentially expressed genes and differentially methylated m6A sites were identified. Conclusion: The findings suggest that m6A modification is altered in the diabetic hippocampus and provide new insight into diabetic hippocampal injury.

Sodium valproate protects against neuronal ferroptosis in epilepsy via suppressing lysyl oxidase

Background and purposeEpilepsy is a chronic neurological disease that is characterized by repetitive seizures. Seizures-related complications such as cognitive deficits, anxiety and sleep disorders seriously impact the life quality of patients. Antiepileptic drugs are widely used for the treatment of epilepsy. Sodium valproate is served as the first-line antiepileptic drugs and possesses various pharmacological effects on the brain. Sodium valproate exerts neuroprotective effects in acute nervous system diseases such as ischemic brain damage by inhibiting oxidative stress. However, the mechanism of neuroprotection of sodium valproate in epilepsy is unclear. Lysyl oxidase (Lox) is a monoamine oxidase that acts on extracellular matrix collagen and elastin and it can promote accumulation of oxidative stress. Our previous studies have confirmed that Lox is involved in ferroptosis, a novel iron-dependent and lipid peroxidation-mediated cell death pathway, during epilepsy. In this study, we would like to investigate whether sodium valproate can exert neuroprotective effects on kainic acid-induced epileptic seizures by inhibiting Lox-mediated ferroptosis.MethodsEpileptic mouse models were established by intracranial injection of 250 ng/μl kainic acid on right hippocampus. Sodium valproate and ferroptosis inhibitors were administrated by intraperitoneal injecting. The epileptic behavior of the mice within 4 hours was recorded after intracranial injection of kainic acid. Mouse hippocampus was acquired to analyze the mRNA expression of prostaglandin-endoperoxide synthase 2 (PTGS2) and the production of 4-hydroxynonenal (4-HNE). In vitro, the protective effects of sodium valproate on glutamate-induced HT22 cell damage model was assessed by PI/Hoechst staining; The levels of PTGS2, 4-HNE and lipid ROS were analyzed by RT-qPCR, western blot and flow cytometry, respectively. RT-qPCR and Western blot analysis the mRNA and protein expression of Lox in the glutamate-induced HT22 cell damage model. The Lox overexpression model was established by intracranial injection of AAV on right hippocampus.ResultsPretreatment with sodium valproate and ferroptosis inhibitors could significantly alleviate the epileptic seizures in the kainic acid induced epilepsy mouse model. Western blot and RT-qPCR results showed that sodium valproate and ferroptosis inhibitors significantly inhibited the levels of 4-HNE and PTGS2. PI/Hoechst staining showed that 1 mM sodium valproate exerted protective effect on glutamate-induced HT22 cell injury model. There was no significant difference observed between sodium valproate and ferroptosis inhibitors co-intervention group and sodium valproate intervention group on glutamate-induced cell injury model. And sodium valproate could significantly inhibit the production of lipid reactive oxygen species and 4-HNE. The expression of Lox was significantly increased in the glutamate-induced HT22 cell injury model, which could be reversed by pretreatment of sodium valproate. And β-aminopropionitrile (a specific inhibitor of Lox) could inhibit ferroptosis induced by glutamate, as well as ameliorate the epileptic seizures in the kainic acid induced epilepsy mouse model. Pretreatment with sodium valproate could not ameliorate the epileptic behavior in the Lox-overexpression mice. Western blot analysis showed that sodium valproate could not suppress the production of 4-HNE in kainic acid induced epileptic mice model.ConclusionsThe neuroprotective effect of sodium valproate in epileptic seizures is closely related to the inhibition of ferroptosis. The inhibition of ferroptosis is involved in the neuroprotective effect of sodium valproate on glutamate-induced HT22 cell damage model. Sodium valproate may exert neuroprotective effects in kainic acid-induced epileptic seizures by abrogating Lox-mediated ferroptosis.

OR01-04 Kruppel-Like Factors 9 and 13 Cooperate to Maintain Mammalian Neuronal Differentiation

During development of the central nervous system, neural cells respond to several external cues that influence cell proliferation, differentiation, axonal growth and synaptogenesis. Thyroid hormone plays a critical role in each of these processes. Previously, we showed that Krüppel-like factor 9 (KLF9), a zinc finger transcription factor, is strongly and directly induced by liganded thyroid hormone receptors, and it mediates the actions of thyroid hormone on neuronal differentiation during late fetal development. Here we analyzed the molecular mechanisms by which KLF9 maintains neuronal structure, and inhibits regeneration in juvenile and adult neuronal cells. We also investigated the actions of the closely related transcription factor KLF13, which is paralogous to KLF9. We engineered the adult mouse hippocampus-derived cell line HT22 to control Klf9 or Klf13 expression by addition of doxycycline. We also used CRISPR/Cas9 genome editing to generate Klf9 or Klf13 knock out (KO), and Klf9+Klf13 double KO HT22 cell lines. To induce neurite outgrowth, we treated cells with forskolin (FK)+IBMX, which increases intracellular cAMP; elevated cAMP is a hallmark of regenerative responses of neurons to injury. Our results show that FK+IBMX increased neurite length in the parent HT22 cell line, and this action was enhanced in Klf9 and Klf13 single KO cells, and was even greater in double KO cells. By contrast, the stimulatory effect of FK+IBMX on neurite outgrowth was blocked by simultaneous forced expression of Klf9 or Klf13 in parent HT22 cells. This effect on neurite outgrowth was confirmed in primary mouse hippocampal neurons, where electroporation of expression plasmids for Klf9 or Klf13 suppressed FK+IBMX-induced neurite extension compared with empty vector-transfected cells. Analysis of RNA-seq data obtained from HT22 cells following 8 hr of induced Klf9 or Klf13 expression showed that both proteins impact the cAMP signaling pathway. Using transfection-reporter assays and chromatin immunoprecipitation, we confirmed that several genes in this pathway are direct targets of both KLFs. Our findings suggest that KLF9 and KLF13 may cooperate to maintain the differentiated state of mammalian neurons and thereby block regeneration, in part, by repressing the cAMP signaling pathway.