Astrocyte-derived Interleukin-31 causes poor prognosis in elderly patients with intracerebral hemorrhage.

The incidence of intracerebral hemorrhage (ICH) is increasing every year, with very high rates of mortality and disability. The prognosis of elderly ICH patients is extremely unfavorable. Interleukin, as an important participant in building the inflammatory microenvironment of the central nervous system after ICH, has long been the focus of neuroimmunology research. However, there are no studies on the role IL31 play in the pathologic process of ICH. We collected para-lesion tissue for immunofluorescence and flow cytometry from the elderly and young ICH patients who underwent surgery. Here, we found that IL31 expression in the lesion of elderly ICH patients was significantly higher than that of young patients. The activation of astrocytes after ICH releases a large amount of IL31, which binds to microglia through IL31R, causing a large number of microglia to converge to the hematoma area, leading to the spread of neuroinflammation, apoptosis of neurons, and ultimately resulting in poorer recovery of nerve function. Interfering with IL31 expression suppresses neuroinflammation and promotes the recovery of neurological function. Our study demonstrated that elderly patients release more IL31 after ICH than young patients. IL31 promotes the progression of neuroinflammation, leading to neuronal apoptosis as well as neurological decline. Suppression of high IL31 concentrations in the brain after ICH may be a promising therapeutic strategy for ICH.

Involvement of Plasma Melatonin in Medication-Overuse Headache: A Cross-Sectional Study.

OBJECTIVES: Patients with medication-overuse headache (MOH) are often complicated with anxiety, depression, and sleep disorders and are associated with dependence behavior and substance abuse. Melatonin has physiological properties including analgesia, regulation of circadian rhythms, soporific, and antidepressant and affects drug preference and addiction. This study aimed to investigate the role of melatonin in MOH compared with episodic migraine (EM) and healthy controls and to verify the relationship between plasma melatonin levels and psychiatric symptoms. METHODS: Thirty patients affected by MOH, 30 patients with EM, and 30 matched healthy controls were enrolled. All subjects completed a detailed headache questionnaire and scales including the Hospital Anxiety and Depression Scale (HADS), the Pittsburgh Sleep Quality Index, the Leeds Dependence Questionnaire. Melatonin levels in plasma samples were measured by enzyme immunoassay method. RESULTS: The levels of plasma melatonin were significantly different among 3 groups of subjects (MOH, 7.74 [5.40-9.89]; EM, 9.79 [8.23-10.62]; Control, 10.16 [8.60-17.57]; H = 13.433; P = 0.001). Significantly lower levels of melatonin were found in MOH patients compared with healthy controls ( P = 0.001). The level of plasma melatonin inversely correlated with the scores of HADS-Anxiety ( r = -0.318, P = 0.002), HADS-Depression ( r = -0.368, P < 0.001), Pittsburgh Sleep Quality Index ( r = -0.303, P = 0.004), and Leeds Dependence Questionnaire ( r = -0.312, P = 0.003). CONCLUSIONS: This study innovatively detects the plasma melatonin levels in MOH patients and explores the association between melatonin levels and psychiatric symptoms. Melatonin may be potential complementary therapy in the treatment of MOH considering its comprehensive role in multiple aspects of MOH.

Deubiquitylating Enzyme OTUB1 Facilitates Neuronal Survival After Intracerebral Hemorrhage Via Inhibiting NF-κB-triggered Apoptotic Cascades.

The deubiquitylase OTU domain-containing ubiquitin aldehyde-binding protein 1 (OTUB1) has been implicated in the pathogenesis of various human diseases. However, the molecular mechanism by which OTUB1 participates in the pathogenesis of intracerebral hemorrhage (ICH) remains elusive. In the present study, we established an autologous whole blood fusion-induced ICH model in C57BL/6 J mice. We showed that the upregulation of OTUB1 contributes to the attenuation of Nuclear factor kappa B (NF-κB) and its downstream apoptotic signaling after ICH. OTUB1 directly associates with NF-κB precursors p105 and p100 after ICH, leading to attenuated polyubiquitylation of p105 and p100. Moreover, we revealed that NF-κB signaling was modestly activated both in ICH tissues and hemin-exposed HT-22 neuronal cells, accompanied with the activation of NF-κB downstream pro-apoptotic signaling. Notably, overexpression of OTUB1 strongly inhibited hemin-induced NF-κB activation, whereas interference of OTUB1 led to the opposite effect. Finally, we revealed that lentiviral transduction of OTUB1 markedly ameliorated hemin-induced apoptotic signaling and HT-22 neuronal death. Collectively, these findings suggest that the upregulation of OTUB1 serves as a neuroprotective mechanism in antagonizing neuroinflammation-induced NF-κB signaling and neuronal death, shed new light on manipulating intracellular deubiquitylating pathways as novel interventive approaches against ICH-induced secondary neuronal damage and death.

Neuroprotective effects of insulin-like growth factor-2 in 6-hydroxydopamine-induced cellular and mouse models of Parkinson's disease.

Skin-derived precursor Schwann cells have been reported to play a protective role in the central nervous system. The neuroprotective effects of skin-derived precursor Schwann cells may be attributable to the release of growth factors that nourish host cells. In this study, we first established a cellular model of Parkinson's disease using 6-hydroxydopamine. When SH-SY5Y cells were pretreated with conditioned medium from skin-derived precursor Schwann cells, their activity was greatly increased. The addition of insulin-like growth factor-2 neutralizing antibody markedly attenuated the neuroprotective effects of skin-derived precursor Schwann cells. We also found that insulin-like growth factor-2 levels in the peripheral blood were greatly increased in patients with Parkinson's disease and in a mouse model of Parkinson's disease. Next, we pretreated cell models of Parkinson's disease with insulin-like growth factor-2 and administered insulin-like growth factor-2 intranasally to a mouse model of Parkinson's disease induced by 6-hydroxydopamine and found that the level of tyrosine hydroxylase, a marker of dopamine neurons, was markedly restored, α-synuclein aggregation decreased, and insulin-like growth factor-2 receptor down-regulation was alleviated. Finally, in vitro experiments showed that insulin-like growth factor-2 activated the phosphatidylinositol 3 kinase (PI3K)/AKT pathway. These findings suggest that the neuroprotective effects of skin-derived precursor Schwann cells on the central nervous system were achieved through insulin-like growth factor-2, and that insulin-like growth factor-2 may play a neuroprotective role through the insulin-like growth factor-2 receptor/PI3K/AKT pathway. Therefore, insulin-like growth factor-2 may be an useful target for Parkinson's disease treatment.

CDK5 Mediates Proinflammatory Effects of Microglia through Activated DRP1 Phosphorylation in Rat Model of Intracerebral Hemorrhage.

Introduction: Cyclin-dependent kinase-5 (CDK5) is a key kinase involved in brain development and function and recently found to be involved in neuronal and astroglial apoptosis, neural stem/progenitor cell stemness, mitochondrial fission, and synaptic transmission. But the specific mechanism of CDK5-mediated anti-inflammatory remains unclear in ICH. The aim of the present study was to explore the role of CDK5 in mediating microglia activity through activated DRP1 phosphorylation in a rat ICH model. Methods: We measured behavioral change after ICH; detected the expression of CDK5 in the rat brain using immunohistochemistry; and measured the protein levels of CDK5, p35, p25, p-histone H1, and p-DRP1 using Western blot analysis. Coimmunoprecipitation analysis indicated interaction of CDK5 and DRP1. Tumor necrosis factor-α, interleukin- (IL-) 1ß, and IL-6 levels were measured using enzyme-linked immunosorbent assay (ELISA). Results: After ICH, CDK5 protein level and kinase activity increased. Western blot data showed that CDK5 expression increased from 6 h and peaked at 2 d after ICH (p < 0.05), and the expression of p35 was lowest at 12 h, while the expression of p25 peaked at 2 d after ICH. Besides, p-DRP1 expression change follows with CDK5 kinase activity change. Coimmunoprecipitation showed that interaction between CDK5 and DRP1 certainly exists in microglia. Then, knockdown CDK5 or p35 expression by siRNA reduced the expression level of p-DRP1. ELISA data showed that the protein levels of proinflammatory mediators, such as TNF-α, IL-1ß, and IL-6, were decreased by knockdown of CDK5. Conclusion: CDK5 may regulate DRP1 by direct phosphorylation in microglia and further induce microglia secreting proinflammation factor.

Blood SSR1: A Possible Biomarker for Early Prediction of Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disease associated with age. Early diagnosis of PD is key to preventing the loss of dopamine neurons. Peripheral-blood biomarkers have shown their value in recent years because of their easy access and long-term monitoring advantages. However, few peripheral-blood biomarkers have proven useful. This study aims to explore potential peripheral-blood biomarkers for the early diagnosis of PD. Three substantia nigra (SN) transcriptome datasets from the Gene Expression Omnibus (GEO) database were divided into a training cohort and a test cohort. We constructed a protein-protein interaction (PPI) network and a weighted gene co-expression network analysis (WGCNA) network, found their overlapping differentially expressed genes and studied them as the key genes. Analysis of the peripheral-blood transcriptome datasets of PD patients from GEO showed that three key genes were upregulated in PD over healthy participants. Analysis of the relationship between their expression and survival and analysis of their brain expression suggested that these key genes could become biomarkers. Then, animal models were studied to validate the expression of the key genes, and only SSR1 (the signal sequence receptor subunit1) was significantly upregulated in both animal models in peripheral blood. Correlation analysis and logistic regression analysis were used to analyze the correlation between brain dopaminergic neurons and SSR1 expression, and it was found that SSR1 expression was negatively correlated with dopaminergic neuron survival. The upregulation of SSR1 expression in peripheral blood was also found to precede the abnormal behavior of animals. In addition, the application of artificial intelligence technology further showed the value of SSR1 in clinical PD prediction. The three classifiers all showed that SSR1 had high predictability for PD. The classifier with the best prediction accuracy was selected through AUC and MCC to construct a prediction model. In short, this research not only provides potential biomarkers for the early diagnosis of PD but also establishes a possible artificial intelligence model for predicting PD.

p75NTR Interacts with the Zinc Finger Protein Glis2 and Participates in Neuronal Apoptosis Following Intracerebral Hemorrhage.

Intracerebral hemorrhage (ICH) is a serious condition with a particularly high mortality rate. Gli-similar 2 (Glis2) has been reported to play an important role in the pathogenesis of ICH; however, its underlying mechanisms and biological significance remains unclear. In the present study, a specific interaction between Glis2 and p75NTR, a member of the tumor necrosis factor receptor superfamily, was identified both in vivo and in vitro. These experiments further indicated that p75NTR may interact with Glis2, and that the complex was transported into the nucleus, initially, inducing neuronal death. Furthermore, the mechanism of neuronal death was explored, and may have been mediated via the activation of the mitochondrial-dependent apoptotic pathway, and this was further investigated in the pathogenesis of ICH in rats in vivo. The study may provide evidences for regulating p75NTR-Glis2 complex as a potential reliable treatment for the secondary damage following ICH.

Schwann cells differentiated from skin-derived precursors provide neuroprotection via autophagy inhibition in a cellular model of Parkinson's disease.

Autophagy has been shown to play an important role in Parkinson's disease. We hypothesized that skin-derived precursor cells exhibit neuroprotective effects in Parkinson's disease through affecting autophagy. In this study, 6-hydroxydopamine-damaged SH-SY5Y cells were pretreated with a culture medium containing skin-derived precursors differentiated into Schwann cells (SKP-SCs). The results showed that the SKP-SC culture medium remarkably enhanced the activity of SH-SY5Y cells damaged by 6-hydroxydopamine, reduced excessive autophagy, increased tyrosine hydroxylase expression, reduced α-synuclein expression, reduced the autophagosome number, and activated the PI3K/AKT/mTOR pathway. Autophagy activator rapamycin inhibited the effects of SKP-SCs, and autophagy inhibitor 3-methyladenine had the opposite effect. These findings confirm that SKP-SCs modulate the PI3K/AKT/mTOR pathway to inhibit autophagy, thereby exhibiting a neuroprotective effect in a cellular model of Parkinson's disease. This study was approved by the Animal Ethics Committee of Laboratory Animal Center of Nantong University (approval No. S20181009-205) on October 9, 2018.

Study of the pathology and the underlying molecular mechanism of tissue injury around hematoma following intracerebral hemorrhage.

Intracerebral hemorrhage (ICH) refers to hemorrhage caused by spontaneous rupture of blood vessels in the brain. Brain injury due to ICH leads to catastrophic effects resulting from the formation of hematoma and oxidative stress caused by components of lysed erythrocytes. However, not all neurons in the area surrounding the hematoma die immediately: A number of neurons remain in a critical, but reversible, state; however, the genes involved in this critical state remain poorly understood. Gene chip technology was used identify changes in the area surrounding the hematoma associated with the upregulation of 210 and downregulation of 173 genes. Gene Ontology functional annotation revealed changes in the gene expression profile in the peripheral region of hematoma following ICH, which were primarily associated with the external stimulation received by the organism, the transmission of harmful information to the cell through the transport of cell membrane proteins, and the regulation of a series of biological processes. Protein interaction network analysis revealed that 11 up­[secreted phosphoprotein 1, dual specificity phosphatase 9, catechol­O­methyltransferase, BAR/IMD domain­containing adaptor protein 2­like 1, plakophilin 2, homer scaffold protein 3, ret proto­oncogene (RET), KIT proto­oncogene, receptor tyrosine kinase, hepsin, connector enhancer of kinase suppressor of Ras 2 and kalirin RhoGEF kinase] and four downregulated genes (transcription factor AP­2ß, peptidylprolyl isomerase A, SHOC2 leucine rich repeat scaffold protein and synuclein α) may serve a significant role in the area around hematoma following ICH. Reverse transcription­quantitative PCR was used to verify that these genes were differentially expressed in the ICH compared with the control group. Causal network analysis suggested that the Achaete­scute homolog 1­RET signaling axis served a key role in the repair of nerve injury in the peripheral region of hematoma following ICH. Additionally, in vivo experiments revealed that RET expression was upregulated and co­localized with neurons. Taken together, these results suggested that the changes in the gene expression profile in the area around hematoma following ICH were primarily associated with the repair of damage caused to the nervous system.

SKP-SCs transplantation alleviates 6-OHDA-induced dopaminergic neuronal injury by modulating autophagy.

Parkinson's disease is a common neurodegenerative disease. Cell transplantation is a promising therapeutic option for improving the survival and function of dopaminergic neurons, but the mechanisms underlying the interaction between the transplanted cells and the recipient neurons remain to be studied. In this study, we investigated the effects of skin precursor cell-derived Schwann cells (SKP-SCs) directly cocultured with 6-OHDA-injured dopaminergic neurons in vitro and of SKP-SCs transplanted into the brains of 6-OHDA-induced PD mice in vivo. In vitro and in vivo studies revealed that SKP-SCs could reduce the damage to dopaminergic neurons by enhancing self-autophagy and modulating neuronal autophagy. Thus, the present study provides the first evidence that cell transplantation mitigates 6-OHDA-induced damage to dopaminergic neurons by enhancing self-autophagy, suggesting that earlier transplantation of Schwann cells might help alleviate the loss of dopaminergic neurons.

PGE1 triggers Nrf2/HO-1 signal pathway to resist hemin-induced toxicity in mouse cortical neurons.

BACKGROUND: Prostaglandin E1 (PGE1) exerts various pharmacological effects such as membrane stabilization, anti-inflammatory functions, vasodilation, and platelet aggregation inhibition. We have previously demonstrated that PGE1 has a beneficial impact on patients suffering from intracerebral hemorrhage (ICH). The related mechanism underlying PGE1's beneficial effect on ICH treatment needs further exploration. METHODS: The present study elucidates the mechanism of PGE1 on ICH treatment using a neuronal apoptosis model in vitro. The mouse primary cortical neurons were pretreated with different concentrations of PGE1, followed by the treatment with hemin, the main catabolite in whole blood, to mimic the clinical ICH. RESULTS: Comparing with the vehicle-treated group, PGE1 prevented cultured cortical neurons from the accumulation of inhibited intracellular levels of reactive oxygen species (ROS), amelioration of mitochondrial membrane potential, and hemin-induced apoptosis. The reduction of ROS and apoptosis were associated with the up-regulation of Heme oxygenase-1 (HO-1) expression. Knockdown of nuclear transcription factor erythroid 2-related factor (Nrf2) by siRNA attenuated the upregulation of HO-1 as well as the protective effect of PGE1. CONCLUSIONS: Our work suggests that the Nrf2/HO-1 molecular pathway may play a crucial role in treating ICH patients with PGE1 and may represent novel molecular targets, resulting in discovering new drugs for ICH treatment.

Intracarotid Transplantation of Skin-Derived Precursor Schwann Cells Promotes Functional Recovery After Acute Ischemic Stroke in Rats.

Purpose: Skin-derived Precursor Schwann cells (SKP-SCs) have been reported to provide neuroprotection for the injured and dysmyelinated nervous system. However, little is known about SKP-SCs on acute ischemic stroke (AIS). We aimed to explore the efficacy and the potential mechanism of action of SKP-SCs on AIS in a rat ischemic stroke model. Methods: Adult male Sprague-Dawley rats were subjected to a middle cerebral artery occlusion (MCAO) for 1.5 h on Day 0 and subsequently received an intracarotid injection of 2 × 106 green fluorescent protein (GFP) -labeled SKP-SCs or phosphate buffered saline (PBS) during reperfusion. Neurological function was assessed by behavioral tests on Days 1, 4, 7, 14, and 28. In a satellite cohort, rat brains were harvested and infarct volume was measured with 2,3,5-triphenyltetrazolium chloride (TTC) staining on Days 1 and 7, and migration and survival of SKP-SCs in the brain were traced by monitoring green fluorescence at 6 and12 h on Day 0, and on Days 1, 4, 7, 14, and 28. Histopathology and immunofluorescence staining were used to analyze the morphology, survival and apoptosis of neurons. Additionally, in an in vitro SKP-SC co-culture model using fetal rat primary cortical neurons underwent oxygen glucose deprivation/reoxygenation (OGD/R), Western blot was used to detect the expression of apoptosis indicators including activated caspase-3, Bax, and Bcl-2. TUNEL staining was used to count apoptotic cells. Results: Intracarotid transplantation of SKP-SCs effectively migrated to the periinfarct area and survived for at least 4 weeks. Transplanted SKP-SCs inhibited neuronal apoptosis, reduced infarct volume, and improved neurological recovery in the MCAO rats. Moreover, in vitro data showed that SKP-SCs treatment inhibited OGD/R-induced neuronal apoptosis and promoted survival of the cultured primary cortical neurons. Conclusions: Intracarotid transplantation of SKP-SCs promoted functional recovery in the rat AIS model and possesses the potential to be further developed as a novel therapy to treat ischemic stroke in humans.

Skin-derived precursor Schwann cells protect SH-SY5Y cells against 6-OHDA-induced neurotoxicity by PI3K/AKT/Bcl-2 pathway.

Skin-derived precursors (SKPs) are self-renewing and pluripotent adult stem cell sources that have been successfully obtained and cultured from adult tissues of rodents and humans. Skin-derived precursor Schwann cells (SKP-SCs), derived from SKPs when cultured in a neuro stromal medium supplemented with some appropriate neurotrophic factors, have been reported to play a neuroprotective effect in the peripheral nervous system. This proves our previous studies that SKP-SCs' function to bridge sciatic nerve gap in rats. However, the function of SKP-SCs in Parkinson disease (PD) remains unknown. This study was aimed to investigate the possible neuroprotective effects of SKP-SCs in 6-OHDA-induced Parkinson's disease (PD) model. Our results showed that the treatment with SKP-SCs prevented SH-SY5Y cells from 6-OHDA-induced apoptosis, accompanied by modulation of apoptosis-related proteins (Bcl-2 and Bax) and the decreased expression of active caspase-3. Furthermore, we confirmed that SKP-SCs might exert protective effects and increase the mitochondrial membrane potential (MMP) through PI3K/AKT/Bcl-2 pathway. Taken together, our results demonstrated that SKP-SCs protect against 6-OHDA-induced cytotoxicity through PI3K/AKT/Bcl-2 pathway in PD model in vitro, which provides a new theoretical basis for the treatment of PD.

Clinical potential and current progress of mesenchymal stem cells for Parkinson's disease: a systematic review.

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease characterized by severe dyskinesia due to a progressive loss of dopaminergic neurons along the nigro-striatal pathway. The current focus of treatment is to relieve symptoms through administration of levodopa, such as L-3,4-dihydroxy phenylalanine replacement therapy, dopaminergic agonist administration, functional neurosurgery, and gene therapy, rather than preventing dopaminergic neuronal damage. Hence, the application and development of neuroprotective/disease modification strategies is absolutely necessary. Currently, stem cell therapy has been considered for PD treatment. As for the stem cells, mesenchymal stem cells (MSCs) seem to be the most promising. In this review, we analyze the mechanisms of action of MSCs in Parkinson's disease, including growth factor secretion, exocytosis, and attenuation of neuroinflammation. To determine efficacy and protect patients from possible adverse effects, ongoing rigorous and controlled studies of MSC treatment will be critical.

Increased expression of Triad1 is associated with neuronal apoptosis after intracerebral hemorrhage in adult rats.

Objective: It has been demonstrated that Triad1 (2 RING fingers and double RING finger linked 1) negatively regulates myeloid cell growth and induces cell apoptosis. However, its functions in intracerebral hemorrhage (ICH) disease have not been conducted. In this study, the role of Triad1 in rat model of ICH was explored.Methods: We observe an increasing expression of Triad1 in areas adjacent to hematoma after ICH. Immunofluorescence shows that Triad1 is colocalized with neurons, while not microglia or astrocyte, indicates its correlation with neuronal activities following ICH.Results: As neuronal apoptosis is the most crucial event in ICH disease, the expression of active caspase-3 and p53 is also enhanced around the hematoma, which is consistent with Triad1 in expression tendency. In turn, Triad1 depletion in primary cortical neurons decreased the apoptosis of neurons after using Triad1 shRNA.Conclusion: We conclude that inhibition of Triad1 expression might protect the brain from secondary damage following ICH.

The p35/CDK5 signaling is regulated by p75NTR in neuronal apoptosis after intracerebral hemorrhage.

The p75 neurotrophin receptor (p75NTR), a member of tumor necrosis factor receptor superfamily, involves in neuronal apoptosis after intracerebral hemorrhage (ICH). It has been previously demonstrated that phosphorylation of p35 is a crucial factor for fighting against the proapoptotic p25/CDK5 signaling in neuronal apoptosis. Then, in ICH models of rats and primary cortical neurons, we found that the expressions of p75NTR, p-histone H1 (the kinase activity of CDK5), p25, Fas-associated phosphatase-1 (FAP-1), and phosphorylated myocyte enhancer factor 2D (p-MEF2D) were enhanced after ICH, whereas the expression of p35-Thr(138) was attenuated. Coimmunoprecipitation analysis indicated several interactions as follows: p35/p25 and CKD5, p75NTR and p35, as well as p75NTR and FAP-1. After p75NTR or FAP-1 depletion with double-stranded RNA interference in PC12 cells, the levels of p25 and p-histone H1 were attenuated, whereas p35-Thr(138) was elevated. Considering p75NTR has no effect of dephosphorylation, our results suggested that p75NTR might promote the dephosphorylation of p35-Thr(138) via interaction with FAP-1, and the p75NTR/p35 complex upregulated p25/CDK5 signaling to facilitate the neuronal apoptosis following ICH. So, in the study, we aimed to provide a theoretical and experimental basis that p75NTR could be regulated to reduce neuronal apoptosis following ICH for potential clinical treatment.

Cab45s inhibits neuronal apoptosis following intracerebral hemorrhage in adult rats.

Recent studies have shown that Cab45s, belonging to the CREC family, can fight against apoptosis in the cancer cell lines. Here, we report that Cab45s may involve in neuronal apoptosis at the early stage of intracerebral hemorrhage (ICH) in pathophysiology. We found that expression of Cab45s was enhanced in areas contiguous to hematoma following ICH in adult rats, and that so were the expressions of Glucose-regulated protein 78 (GRP78), pro-apoptotic Bcl-2-associated X protein (Bax) and active caspase-3. In vitro, coimmunoprecipitation analysis indicated the interaction between Cab45s and GRP78. Depletion of Cab45s attenuated the expression of GRP78, but increased the expressions of Bax and caspase-3 in PC12 cells treated with hemin, which finally promoted apoptosis. Together, these results reveal that Cab45s might exert its anti-apoptotic function against neuronal apoptosis. Thus, the study may provide evidences for regulating Cab45s as a potentially reliable treatment for the secondary damage following ICH.

Bex1 attenuates neuronal apoptosis in rat intracerebral hemorrhage model.

Brain expressed x-linked gene 1 (Bex1) which is at high levels in several populations of central nervous system (CNS) neurons, belongs to a family of small proteins of unknown function, playing roles as adaptors or modulators of intracellular signaling pathways. But its distribution and function in CNS remains unclear. Neuronal apoptosis is the major pathogenesis in secondary brain injury of intracerebral hemorrhage (ICH). In this study, the roles of Bex1 were explored in the pathophysiology of ICH. Western blot, immunohistochemistry, and immunofluorescence showed that obvious up-regulation of Bex1 in neurons adjacent to the hematoma after ICH. Furthermore, the increase of Bex1 expression was accompanied by the enhanced expression of Bax and active caspase-3, and decreased expression of B-cell lymphoma 2 (Bcl-2) following ICH. The in vitro study using Bex1 siRNA transfection in hemin-exposed PC12 cells suggested that Bex1 exerted anti-apoptotic function. Therefore, Bex1 may play the neuronal anti-apoptosis role following ICH, implying a novel molecular target for the therapy of ICH.

SSTR2 associated with neuronal apoptosis after intracerebral hemorrhage in adult rats.

Objective SSTR2 is a member of superfamily of SST receptor (SSTR), and widely expressed in the brain; however, the knowledge of its functions in area adjacent to hematoma after intracerebral hemorrhage (ICH) is still limited. Method The role of SSTR2 in the processes of ICH was explored by conducting an ICH rat model. Western blot and immunohistochemistry were employed to examine the level of SSTR2 in area adjacent to hematoma after ICH. Immunofluorescent staining was used to observe the spatial correlation of SSTR2 with cellular types adjacent to hematoma after ICH. RNA interference specific to SSTR2 was adopted in PC12 cells to clarify the causal correlation between SSTR2 and neuronal activities. Results Increased expression of SSTR2 was observed and restricted to the neurons adjacent to hematoma following ICH. Immunofluorescent staining showed that SSTR2 was significant increased in neurons, but not astrocytes or microglia. Increasing SSTR2 level was found to be accompanied by the up-regulation of activated caspase-3 and the down-expression of p-Akt in a time-dependent manner. What's more, using SSTR2 RNA interference (SSTR2-RNAi) in PC12 cells, we indicated that SSTR2 might have a pro-apoptotic role in neurons. Conclusion We speculated that SSTR2 might exert its pro-apoptotic function in neurons through inhibiting Akt activity following ICH.

p75 neurotrophin receptor and its novel interaction partner, NIX, are involved in neuronal apoptosis after intracerebral hemorrhage.

Recently, NIX, a pro-apoptotic BH3-only protein, was found to be a novel p75 neurotrophin receptor (p75NTR) binding protein by screening a human fetal brain two-hybrid library in our laboratory. We further study the interaction of these two proteins and the possible roles of p75NTR and NIX in intracerebral hemorrhage (ICH)-induced neuronal death. Using the split-ubiquitin yeast two-hybrid system, we found that the "Copper" domain in p75NTR and the TM region in NIX were sufficient for the interaction of these two proteins. Co-immunoprecipitation and in vitro binding assays demonstrated the direct interaction between p75NTR and NIX. NIX protein was stabilized by p75NTR at post-translational levels. Moreover, p75NTR was able to work together with NIX to promote apoptosis and affected the NIX-induced JNK-p53-Bax pathway in neuronal PC12 cells. Previous work has indicated that p75NTR and NIX are induced in neurons in human ICH and the rat ICH model, respectively. We confirm that both p75NTR and NIX levels were up-regulated in glutamate-treated primary cortical neurons (a cellular in vitro model for ICH) and in the rat ICH model. Glutamate exposure increased the association between p75NTR and NIX and elevated the activation of the JNK-p53-Bax pathway and neuronal apoptosis; all of these observations were similar in the rat ICH model. Importantly, p75NTR and NIX appeared to be involved in cortical neuronal apoptosis, because knockdown of p75NTR or NIX not only inhibited the JNK pathway but also impaired neuronal apoptosis. Thus, p75NTR and NIX may play critical roles in ICH-induced neuronal apoptosis in vitro and in vivo.