Apoptosis signal-regulating kinase 1 (ASK1) is linked to neural stem cell differentiation after ischemic brain injury

Small-molecule inhibitors targeting apoptosis signal-regulated kinase 1

Apoptosis signal regulated kinase 1 (ASK1, also known as MAP3K5) is a member of the mitogen activated protein kinase kinase kinase (MAP3K) family. Since its first isolation from a human macrophage library in 1996, its research has been ongoing for over 25 years. A large number of reports have revealed that ASK1, as a key activator of the p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK) signaling cascade, responds to various stressors, and its inhibitors have important potential value in the treatment of diseases such as inflammation, cancer, and the nervous system and so on. This review summarizes the recent development in this field, including the structure and signaling pathways of ASK1, with a particular focus on the structure-activity relationships, and the hit-to-lead optimization strategies.

Triazole fungicides exert neural differentiation alteration through H3K27me3 modifications: In vitro and in silico study

Considering that humans are unavoidably exposed to triazole fungicides through the esophagus, respiratory tract, and skin contact, revealing the developmental toxicity of triazole fungicides is vital for health risk assessment. This study aimed to screen and discriminate neural developmental disorder chemicals in commonly used triazole fungicides, and explore the underlying harmful impacts on neurogenesis associated with histone modification abnormality in mouse embryonic stem cells (mESCs). The triploblastic and neural differentiation models were constructed based on mESCs to expose six typical triazole fungicides (myclobutanil, tebuconazole, hexaconazole, propiconazole, difenoconazole, and flusilazole). The result demonstrated that although no cytotoxicity was observed, different triazole fungicides exhibited varying degrees of alterations in neural differentiation, including increased ectodermal differentiation, promoted neurogenesis, increased intracellular calcium ion levels, and disturbance of neurotransmitters. Molecular docking, cluster analysis, and multiple linear regressions demonstrated that the binding affinities between triazole fungicides and the Kdm6b-ligand binding domain were the dominant determinants of the neurodevelopmental response. This partially resulted in the reduced enrichment of H3K27me3 at the promoter region of the serotonin receptor 2 C gene, finally leading to disturbed neural differentiation. The data suggested potential adverse outcomes of triazole fungicides on embryonic neurogenesis even under sublethal doses through interfering histone modification, providing substantial evidence on the safety control of fungicides.

Neural stem cell-derived exosome as a nano-sized carrier for BDNF delivery to a rat model of ischemic stroke

Our previous study demonstrated the potential therapeutic role of human neural stem cell-derived exosomes (hNSC-Exo) in ischemic stroke. Here, we loaded brain-derived neurotrophic factor (BDNF) into exosomes derived from NSCs to construct engineered exosomes (BDNF-hNSC-Exo) and compared their effects with those of hNSC-Exo on ischemic stroke both in vitro and in vivo. In a model of H₂O₂-induced oxidative stress in NSCs, BDNF-hNSC-Exo markedly enhanced cell survival. In a rat middle cerebral artery occlusion model, BDNF-hNSC-Exo not only inhibited the activation of microglia, but also promoted the differentiation of endogenous NSCs into neurons. These results suggest that BDNF can improve the function of NSC-derived exosomes in the treatment of ischemic stroke. Our research may support the clinical use of other neurotrophic factors for central nervous system diseases.

Oxidative Stress in Ischemia/Reperfusion Injuries following Acute Ischemic Stroke

Recanalization therapy is increasingly used in the treatment of acute ischemic stroke. However, in about one third of these patients, recanalization is followed by ischemia/reperfusion injuries, and clinically to worsening of the neurological status. Much research has focused on unraveling the involved mechanisms in order to prevent or efficiently treat these injuries. What we know so far is that oxidative stress and mitochondrial dysfunction are significantly involved in the pathogenesis of ischemia/reperfusion injury. However, despite promising results obtained in experimental research, clinical studies trying to interfere with the oxidative pathways have mostly failed. The current article discusses the main mechanisms leading to ischemia/reperfusion injuries, such as mitochondrial dysfunction, excitotoxicity, and oxidative stress, and reviews the clinical trials with antioxidant molecules highlighting recent developments and future strategies.

Angelica sinensis extract promotes neuronal survival by enhancing p38 MAPK-mediated hippocampal neurogenesis and dendritic growth in the chronic phase of transient global cerebral ischemia in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Angelica sinensis (Oliv.) Diels (ASD), commonly known as Dang Gui, is a popular Chinese herb that has long been used to treat ischemic stroke. However, the effects of ASD in chronic cerebral ischemia and its underlying mechanisms still remain unclear.

AIM OF THE STUDY

This study aimed to determine the effects of the ASD extract on hippocampal neuronal survival at 28 d after transient global cerebral ischemia (GCI) and to investigate the precise mechanisms underlying the p38 mitogen-activated protein kinase (MAPK)-related signaling pathway's involvement in hippocampal neurogenesis.

MATERIALS AND METHODS

Rats underwent 25 min of four-vessel occlusion. The ASD extract was intragastrically administered at doses of 0.25 g/kg (ASD-0.25 g), 0.5 g/kg (ASD-0.5 g), 1 g/kg (ASD-1 g), 1 g/kg after dimethyl sulfoxide administration (D + ASD-1 g), or 1 g/kg after SB203580 (a p38 MAPK inhibitor) administration (SB + ASD-1 g) at 1, 3, 7, 10, 14, 17, 21, and 24 d after transient GCI.

RESULTS

ASD-0.5 g, ASD-1 g, and D + ASD-1 g treatments had the following effects: upregulation of bromodeoxyuridine (BrdU) and Ki67 expression, and BrdU/neuronal nuclei (NeuN) and Ki67/nestin co-expression in the hippocampal dentate gyrus (DG); upregulation of microtubule-associated protein 2/NeuN co-expression, and NeuN and glial fibrillary acidic protein (GFAP) expression, and downregulation of tumor necrosis factor-α/GFAP co-expression in the hippocampal CA1 region; upregulation of phospho-p38 MAPK (p-p38 MAPK), phospho-cAMP response element-binding protein (p-CREB), brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and vascular endothelial growth factor A (VEGF-A) expression in the hippocampus. SB + ASD-1 g treatment abrogated the effects of ASD-1 g on the expression of these proteins.

CONCLUSIONS

ASD-0.5 g and ASD-1 g treatments promotes neuronal survival by enhancing hippocampal neurogenesis. The effects of the ASD extract on astrocyte-associated hippocampal neurogenesis and dendritic growth are caused by the activation of p38 MAPK-mediated CREB/BDNF, GDNF, and VEGF-A signaling pathways in the hippocampus at 28 d after transient GCI.

Selonsertib Inhibits Liver Fibrosis via Downregulation of ASK1/ MAPK Pathway of Hepatic Stellate Cells

Liver fibrosis constitutes a significant health problem worldwide due to its rapidly increasing prevalence and the absence of specific and effective treatments. Growing evidence suggests that apoptosis-signal regulating kinase 1 (ASK1) is activated in oxidative stress, which causes hepatic inflammation and apoptosis, leading to liver fibrogenesis through a mitogen-activated protein kinase (MAPK) downstream signals. In this study, we investigated whether selonsertib, a selective inhibitor of ASK1, shows therapeutic efficacy for liver fibrosis, and elucidated its mechanism of action in vivo and in vitro. As a result, selonsertib strongly suppressed the growth and proliferation of hepatic stellate cells (HSCs) and induced apoptosis by increasing Annexin V and TUNEL-positive cells. We also observed that selonsertib inhibited the ASK1/MAPK pathway, including p38 and c-Jun N-terminal kinase (JNK) in HSCs. Interestingly, dimethylnitrosamine (DMN)-induced liver fibrosis was significantly alleviated by selonsertib treatment in rats. Furthermore, selonsertib reduced collagen deposition and the expression of extracellular components such as α-smooth muscle actin (α-SMA), fibronectin, and collagen type I in vitro and in vivo. Taken together, selonsertib suppressed fibrotic response such as HSC proliferation and extracellular matrix components by blocking the ASK1/MAPK pathway. Therefore, we suggest that selonsertib may be an effective therapeutic drug for ameliorating liver fibrosis.

Regulation of Cellular Stress Signaling in Bladder Ischemia

Introduction

The etiology of lower urinary tract symptoms in patients with non-obstructed non-neurogenic bladder remains largely unknown. Clinical studies divulged a significant correlation between reduced bladder blood flow and low bladder compliance. Animal models of bladder ischemia displayed structural modifications, characterized by loss of smooth muscle cells and accumulation of connective tissue in the bladder wall. The underlying mechanisms contributing to structural damage in bladder ischemia remain largely elusive. We previously reported that structural modifications in bladder ischemia correlate with upregulated stress proteins and cell survival signaling, suggesting the potential role of cellular stress in ischemic damage. However, stress response molecules and downstream pathways eliciting bladder damage in ischemia remain largely undetermined.

Methods

Using a rat model of bladder ischemia along with a cell culture hypoxia model, we investigated stress signaling molecules in the ischemic bladder tissues and hypoxic bladder smooth muscle cells.

Results

Our data suggest simultaneous upregulation of two major cellular stress-sensing molecules, namely apoptosis signal-regulating kinase 1 (ASK1) and caspase-3, implying degenerative insult via stress signaling pathway in bladder ischemia. Consistent with bladder ischemia, incubation of cultured human bladder smooth muscle cells at low oxygen tension increased both ASK1 and caspase-3 expression, insinuating hypoxia as an essential factor in ASK1 and caspase-3 upregulation. Gene deletion of ASK1 by ASK1 siRNA in cultured smooth muscle cells prevented caspase-3 upregulation by hypoxia, suggesting caspase-3 regulation by ASK1 under the ischemic/hypoxic conditions. Upregulation of ASK1 and caspase-3 in rat bladder ischemia and human bladder smooth muscle cell hypoxia was associated with subcellular structural modifications consistent with the initial stages of apoptotic insult.

Conclusion

Our data suggest that stress sensing by ASK1 and caspase-3 may contribute to subcellular structural damage and low bladder compliance. The ASK1/caspase-3 pathway may provide therapeutic targets against cellular stress and degenerative responses in bladder ischemia.

Cronobacter sakazakii Infection in Early Postnatal Rats Impaired Contextual-Associated Learning: a Putative Role of C5a-Mediated NF-κβ and ASK1 Pathways

This study was designed to test whether the Cronobacter sakazakii infection-impaired contextual learning and memory are mediated by the activation of the complement system; subsequent activation of inflammatory signals leads to alternations in serotonin transporter (SERT). To test this, rat pups (postnatal day, PND 15) were treated with either C. sakazakii (10⁷ CFU) or Escherichia coli OP50 (10⁷ CFU) or Luria bertani broth (100 μL) through oral gavage and allowed to stay with their mothers until PND 24. Experimental groups' rats were allowed to explore (PNDs 31-35) and then trained in contextual learning task (PNDs 36-43). Five days after training, individuals were tested for memory retention (PNDs 49-56). Observed behavioural data showed that C. sakazakii infection impaired contextual-associative learning and memory. Furthermore, our analysis showed that C. sakazakii infection activates complement system complement anaphylatoxin (C5a) (a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS1)) and mitogen-activated protein kinase kinase1 (MEKK1). Subsequently, MEKK1 induces pro-inflammatory signals possibly through apoptosis signal-regulating kinase-1 (ASK-1), c-Jun N-terminal kinase (JNK1/3) and protein kinase B gamma (AKT-3). In parallel, activated nuclear factor kappa-light-chain-enhancer B cells (NF-κB) induces interleukin-6 (IL-6) and IFNα-1, which may alter the level of serotonin transporter (SERT). Observed results suggest that impaired contextual learning and memory could be correlated with C5a-mediated NF-κβ and ASK1 pathways.

Resveratrol ameliorates brain injury via the TGF-β-mediated ERK signaling pathway in a rat model of cerebral hemorrhage

Brain injury is the most common intracranial injury in human cerebrovascular disease, which may lead to ischemic stroke. Resveratrol induces ameliorative effects in the treatment of certain human diseases by regulating different signaling pathways. The present study assessed the therapeutic effects of resveratrol and its potential mechanism of action in the neurons from rats with ischemia/reperfusion-induced cerebral hemorrhage. The rat model of cerebral hemorrhage was established and reverse transcription-quantitative polymerase chain reaction, western blotting, immunohistochemistry and terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling assays were subsequently performed to assess the therapeutic effects of resveratrol. The results demonstrated that treatment with resveratrol (10 mg/kg/day) decreased cerebral water content, hippocampal cell apoptosis and cerebral infarct volume compared with the PBS-treated group. Resveratrol treatment also increased neuronal cell viability, improved neurological function and blood brain barrier disruption compared with the PBS group following 21 days of treatment. The administration of resveratrol was demonstrated to decrease the levels of certain inflammatory factors, including ionized calcium binding adaptor molecule 1 and myeloperoxidase, in rats with cerebral hemorrhage. The results revealed that treatment with resveratrol regulated neuronal apoptosis by downregulating the transforming growth factor-β (TGF-β)-mediated extracellular signal-regulated kinase (ERK) signaling pathway. In conclusion, these results indicate that resveratrol decreases ischemia/reperfusion-induced neuronal apoptosis by downregulating the TGF-β-mediated ERK pathway in a rat model of cerebral hemorrhage and may serve as a potential agent for the treatment of cerebral hemorrhage.

Danger signals activate a putative innate immune system during regeneration in a filamentous fungus

The ability to respond to injury is a biological process shared by organisms of different kingdoms that can even result in complete regeneration of a part or structure that was lost. Due to their immobility, multicellular fungi are prey to various predators and are therefore constantly exposed to mechanical damage. Nevertheless, our current knowledge of how fungi respond to injury is scarce. Here we show that activation of injury responses and hyphal regeneration in the filamentous fungus Trichoderma atroviride relies on the detection of two danger or alarm signals. As an early response to injury, we detected a transient increase in cytosolic free calcium ([Ca²⁺]_c) that was promoted by extracellular ATP, and which is likely regulated by a mechanism of calcium-induced calcium-release. In addition, we demonstrate that the mitogen activated protein kinase Tmk1 plays a key role in hyphal regeneration. Calcium- and Tmk1-mediated signaling cascades activated major transcriptional changes early following injury, including induction of a set of regeneration associated genes related to cell signaling, stress responses, transcription regulation, ribosome biogenesis/translation, replication and DNA repair. Interestingly, we uncovered the activation of a putative fungal innate immune response, including the involvement of HET domain genes, known to participate in programmed cell death. Our work shows that fungi and animals share danger-signals, signaling cascades, and the activation of the expression of genes related to immunity after injury, which are likely the result of convergent evolution.

The idea of regenerating lost body parts has always fascinated humans due to its impact on human health. Recently, the study of the response to damage has gained importance not only in regenerative medicine, but also in organ transplantation. We have established a microbial model that given its relative simplicity and ease to work with, promises to accelerate the advance of our understanding of damage responses and regeneration. We show that activation of injury responses and hyphal regeneration in a filamentous fungus relies on the detection of danger (also called alarm) signals also used by plants and animals. Finally, we discovered a set of genes that become active in response to injury, including those putatively participating in the immune response.

Advances in stroke pharmacology

Stroke occurs when a cerebral blood vessel is blocked or ruptured, and it is the major cause of death and adult disability worldwide. Various pharmacological agents have been developed for the treatment of stroke either through interrupting the molecular pathways leading to neuronal death or enhancing neuronal survival and regeneration. Except for rtPA, few of these agents have succeeded in clinical trials. Recently, with the understanding of the pathophysiological process of stroke, there is a resurrection of research on developing neuroprotective agents for stroke treatment, and novel molecular targets for neuroprotection and neurorestoration have been discovered to predict or offer clinical benefits. Here we review the latest major progress of pharmacological studies in stroke, especially in ischemic stroke; summarize emerging potential therapeutic mechanisms; and highlight recent clinical trials. The aim of this review is to provide a panorama of pharmacological interventions for stroke and bridge basic and translational research to guide the clinical management of stroke therapy.

GRP78 Promotes Neural Stem Cell Antiapoptosis and Survival in Response to Oxygen-Glucose Deprivation (OGD)/Reoxygenation through PI3K/Akt, ERK1/2, and NF-κB/p65 Pathways

When brain injury happens, endogenous neural stem cells (NSCs) located in the adult subventricular zone (SVZ) and subgranular zone (SGZ) are attacked by ischemia/reperfusion to undergo cellular apoptosis and death before being induced to migrate to the lesion point and differentiate into mature neural cells for damaged cell replacement. Although promoting antiapoptosis and NSC survival are critical to neuroregeneration, the mechanism has yet been elucidated clearly. Here in this study, we established an in vitro oxygen-glucose deprivation (OGD)/reoxygenation model on NSCs and detected glucose-regulated protein 78 (GRP78) involved in apoptosis, while in the absence of GRP78 by siRNA transfection, OGD/reoxygenation triggered PI3K/Akt, ERK1/2, and NF-κB/p65 activation, and induced NSC apoptosis was attenuated. Further investigation, respectively, with the inhibitor of PI3K/Akt or ERK1/2 demonstrated a blockage on GRP78 upregulation, while the inhibition of NF-κB rarely affected GRP78 induction by OGD/reoxygenation. The results indicated the bidirectional regulations of GRP78-PI3K/Akt and GRP78-ERK1/2 and the one-way signalling transduction through GRP78 to NF-κB/p65 on NSC survival from OGD/reoxygenation. In conclusion, we found that GRP78 mediated the signalling cross talk through PI3K/Akt, ERK1/2, and NF-κB/p65, which leads to antiapoptosis and NSC survival from ischemic stroke. Our finding gives a new evidence of GRP78 in NSCs as well as a new piece of signalling mechanism elucidation to NSC survival from ischemic stroke.

Targeting incretin hormones and the ASK-1 pathway as therapeutic options in the treatment of non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is currently one of the leading forms of chronic liver disease, and its rising frequency worldwide has reached epidemic proportions. NAFLD, particularly its progressive variant NASH (non-alcoholic steatohepatitis), can lead to advanced fibrosis, cirrhosis, and HCC. The pathophysiologic mechanisms that contribute to the development and progression of NAFLD and NASH are complex, and as such myriad therapies are under investigation targeting different pathophysiological mechanisms. Incretin-based therapies, including GLP-1RAs and DPP-4 inhibitors and the inhibition of ASK1 pathway have provided two such novel mechanisms in the management of this disease, and will remain focus of this review.

Free Radical Damage in Ischemia-Reperfusion Injury: An Obstacle in Acute Ischemic Stroke after Revascularization Therapy

Acute ischemic stroke is a common cause of morbidity and mortality worldwide. Thrombolysis with recombinant tissue plasminogen activator and endovascular thrombectomy are the main revascularization therapies for acute ischemic stroke. However, ischemia-reperfusion injury after revascularization therapy can result in worsening outcomes. Among all possible pathological mechanisms of ischemia-reperfusion injury, free radical damage (mainly oxidative/nitrosative stress injury) has been found to play a key role in the process. Free radicals lead to protein dysfunction, DNA damage, and lipid peroxidation, resulting in cell death. Additionally, free radical damage has a strong connection with inducing hemorrhagic transformation and cerebral edema, which are the major complications of revascularization therapy, and mainly influencing neurological outcomes due to the disruption of the blood-brain barrier. In order to get a better clinical prognosis, more and more studies focus on the pharmaceutical and nonpharmaceutical neuroprotective therapies against free radical damage. This review discusses the pathological mechanisms of free radicals in ischemia-reperfusion injury and adjunctive neuroprotective therapies combined with revascularization therapy against free radical damage.

Apoptosis signal-regulating kinase 1 mediates the inhibitory effect of hepatocyte nuclear factor-4α on hepatocellular carcinoma

Previous studies provided substantial evidence of a striking suppressive effect of hepatocyte nuclear factor 4α (HNF4α) on hepatocellular carcinoma (HCC). Apoptosis signal-regulating kinase 1 (ASK1) is involved in death receptor-mediated apoptosis and may acts as a tumor suppressor in hepatocarcinogenesis. However, the status and function of ASK1 during HCC progression are unclear. In this study, we found that HNF4α increased ASK1 expression by directly binding to its promoter. ASK1 expression was dramatically suppressed and correlated with HNF4α levels in HCC tissues. Reduced ASK1 expression was associated with aggressive tumors and poor prognosis for human HCC. Moreover, ASK1 inhibited the malignant phenotype of HCC cells in vitro. Intratumoral ASK1 injection significantly suppressed the growth of subcutaneous HCC xenografts in nude mice. More interestingly, systemic ASK1 delivery strikingly inhibited the growth of orthotopic HCC nodules in NOD/SCID mice. In addition, inhibition of endogenous ASK1 partially reversed the suppressive effects of HNF4α on HCC. Collectively, this study highlights the suppressive effect of ASK1 on HCC and its biological significance in HCC development. These outcomes broaden the knowledge of ASK1 function in HCC progression, and provide a novel potential prognostic biomarker and therapeutic target for advanced HCC.

Association Between Serum MicroRNAs and Magnetic Resonance Imaging Measures of Multiple Sclerosis Severity

Importance

MicroRNAs (miRNAs) are promising multiple sclerosis (MS) biomarkers. Establishing the association between miRNAs and magnetic resonance imaging (MRI) measures of disease severity will help define their significance and potential impact.

Objective

To correlate circulating miRNAs in the serum of patients with MS to brain and spinal MRI.

Design, Setting, and Participants

A cross-sectional study comparing serum miRNA samples with MRI metrics was conducted at a tertiary MS referral center. Two independent cohorts (41 and 79 patients) were retrospectively identified from the Comprehensive Longitudinal Investigation of Multiple Sclerosis at the Brigham and Women's Hospital. Expression of miRNA was determined by locked nucleic acid-based quantitative real-time polymerase chain reaction. Spearman correlation coefficients were used to test the association between miRNA and brain lesions (T2 hyperintense lesion volume [T2LV]), the ratio of T1 hypointense lesion volume [T1LV] to T2LV [T1:T2]), brain atrophy (whole brain and gray matter), and cervical spinal cord lesions (T2LV) and atrophy. The study was conducted from December 2013 to April 2016.

Main Outcomes and Measures

miRNA expression.

Results

Of the 120 patients included in the study, cohort 1 included 41 participants (7 [17.1%] men), with mean (SD) age of 47.7 (9.5) years; cohort 2 had 79 participants (26 [32.9%] men) with a mean (SD) age of 43.0 (7.5) years. Associations between miRNAs and MRIs were both protective and pathogenic. Regarding miRNA signatures, a topographic specificity differed for the brain vs the spinal cord, and the signature differed between T2LV and atrophy/destructive measures. Four miRNAs showed similar significant protective correlations with T1:T2 in both cohorts, with the highest for hsa.miR.143.3p (cohort 1: Spearman correlation coefficient rs = -0.452, P = .003; cohort 2: rs = -0.225, P = .046); the others included hsa.miR.142.5p (cohort 1: rs = -0.424, P = .006; cohort 2: rs = -0.226, P = .045), hsa.miR.181c.3p (cohort 1: rs = -0.383, P = .01; cohort 2: rs = -0.222, P = .049), and hsa.miR.181c.5p (cohort 1: rs = -0.433, P = .005; cohort 2: rs = -0.231, P = .04). In the 2 cohorts, hsa.miR.486.5p (cohort 1: rs = 0.348, P = .03; cohort 2: rs = 0.254, P = .02) and hsa.miR.92a.3p (cohort 1: rs = 0.392, P = .01; cohort 2: rs = 0.222, P = .049) showed similar significant pathogenic correlations with T1:T2; hsa.miR.375 (cohort 1: rs = -0.345, P = .03; cohort 2: rs = -0.257, P = .022) and hsa.miR.629.5p (cohort 1: rs = -0.350, P = .03; cohort 2: rs = -0.269, P = .02) showed significant pathogenic correlations with brain atrophy. Although we found several miRNAs associated with MRI outcomes, none of these associations remained significant when correcting for multiple comparisons, suggesting that further validation of our findings is needed.

Conclusions and Relevance

Serum miRNAs may serve as MS biomarkers for monitoring disease progression and act as surrogate markers to identify underlying disease processes.

Differential expression of survival proteins during decreased intracellular oxygen tension in brain endothelial cells of grey mullets

The brain requires constant oxygen supply to perform its biological functions essential for survival. Because of low oxygen capacity and poor oxygen diffusibility of water, many fish species have evolved various adaptive mechanisms to cope with depleted oxygen. Endothelial cells (EC) are the primary components responsible for controlled environment of brain. Brain homeostasis largely depends on integrity of the EC. To elucidate their adaptive strategy, EC were isolated from the fish brain of Kovalam-control site and Ennore estuary-test/field hypoxic site and were subjected to low oxygen tension in laboratory. Cell viability, 4-hydroxynonenal (4HNE) and total antioxidant capacity (TAC) were analyzed to ascertain stress. Hypoxic insult, cytoprotective role of HSPs and apoptotic effect were analyzed by assessing hypoxia-inducible-factor-α (HIF1α), heat-shock-protein-70 (HSP70), heme-oxygenase 1 (HO-1), and apoptosis signal regulating kinase-1 (ASK1). This study evidenced that HSP70 and HO-1 are the key stress proteins, confer high tolerance to decreased oxygen tension mediated stress.

Stem cells and combination therapy for the treatment of traumatic brain injury

TBI is a nondegenerative, noncongenital insult to the brain from an external mechanical force; for instance a violent blow in a car accident. It is a complex injury with a broad spectrum of symptoms and has become a major cause of death and disability in addition to being a burden on public health and societies worldwide. As such, finding a therapy for TBI has become a major health concern for many countries, which has led to the emergence of many monotherapies that have shown promising effects in animal models of TBI, but have not yet proven any significant efficacy in clinical trials. In this paper, we will review existing and novel TBI treatment options. We will first shed light on the complex pathophysiology and molecular mechanisms of this disorder, understanding of which is a necessity for launching any treatment option. We will then review most of the currently available treatments for TBI including the recent approaches in the field of stem cell therapy as an optimal solution to treat TBI. Therapy using endogenous stem cells will be reviewed, followed by therapies utilizing exogenous stem cells from embryonic, induced pluripotent, mesenchymal, and neural origin. Combination therapy is also discussed as an emergent novel approach to treat TBI. Two approaches are highlighted, an approach concerning growth factors and another using ROCK inhibitors. These approaches are highlighted with regard to their benefits in minimizing the outcomes of TBI. Finally, we focus on the consequent improvements in motor and cognitive functions after stem cell therapy. Overall, this review will cover existing treatment options and recent advancements in TBI therapy, with a focus on the potential application of these strategies as a solution to improve the functional outcomes of TBI.

Differential regulation of pro- and antiapoptotic proteins in fish adipocytes during hypoxic conditions

Worldwide, the frequencies and magnitudes of hypoxic events in estuarine waters have increased considerably over the past two decades. Fish populations are suitable indicators for the assessment of quality of aquatic ecosystems and often comprise a variety of adaptation systems by triggering oxidants, antioxidants and hypoxia-responsive signaling proteins. Signaling pathway may lead to cell survival or cell death which is fine-tuned by both positive and negative factors, which includes hypoxia-inducible factor-1α (HIF1α), heat-shock protein-70 (HSP70), phospho-c-Jun N-terminal kinase 1/2 (p-JNK1/2) and apoptosis signal-regulating kinase-1 (ASK1). In the present study, we attempt to determine stress-mediated signaling changes and molecular mechanism behind the cell survival by comparing adipocytes of fish from field hypoxic condition and laboratory-induced hypoxic condition (in vitro hypoxia). Comparison of field and laboratory studies in fish adipocytes showed differential expression of HIF1α, HSP70, p-JNK1/2 and ASK1 with altered oxidants and antioxidants. Further, the results also suggest that in vitro hypoxic conditions mimic field hypoxic conditions. Trends of hypoxia response were same in in vitro hypoxia of control adipocytes as in Ennore estuary, and hypoxia response was more pronounced in the test adipocytes under in vitro hypoxic condition. Results of the present work suggest that hypoxia is the major crusade of water pollutants affecting fish by differential regulation of pro- and antiapoptotic proteins probably through HSP70. This may play a vital role by providing cytoprotection in pollutant-induced stressed fish adipocytes substantiated by the in vitro hypoxic studies.

Connexins and pannexins in neuronal development and adult neurogenesis

Connexins and pannexins share very similar structures and functions; they also exhibit overlapping expression in many stages of neuronal development. Here, we review evidence implicating connexin- and pannexin-mediated communication in the regulation of the birth and development of neurons, specifically Cx26, Cx30, Cx32, Cx36, Cx43, Cx45, Panx1, and Panx2. We begin by dissecting the involvement of these proteins in the generation and development of new neurons in the embryonic, postnatal, and adult brain. Next we briefly outline common mechanisms employed by both pannexins and connexins in these roles, including modulation of purinergic receptor signalling and signalling nexus functions. Throughout this review we highlight developing themes as well as important gaps in knowledge to be bridged.

Delayed Treatment with Green Tea Polyphenol EGCG Promotes Neurogenesis After Ischemic Stroke in Adult Mice

(-)-Epigallocatechin-3‑gallate (EGCG), the predominant constituent of green tea, has been demonstrated to be neuroprotective against acute ischemic stroke. However, the long-term actions of EGCG on neurogenesis and functional recovery after ischemic stroke have not been identified. In this study, C57BL/6 mice underwent middle cerebral artery occlusion (60 min) followed by reperfusion for 28 days. Neural progenitor cells (NPCs) were isolated from ipsilateral subventricular zone (SVZ) at 14 days post-ischemia (dpi). The effects of EGCG on the proliferation and differentiation of NPCs were examined in vivo and in vitro. Behavioral assessments were made 3 days before MCAO and at 28 dpi. SVZ NPCs were stimulated with lipopolysaccharide (LPS) in vitro to mimic the inflammatory response after ischemic stroke. We found that 14 days treatment with EGCG significantly increased the proliferation of SVZ NPCs and the migration of SVZ neuroblasts, as well as functional recovery, perhaps through M2 phenotype induction in microglia. LPS stimulation promoted the neuronal differentiation in cultured NPCs from the ischemic SVZ. EGCG treatment (20 or 40 μM) further significantly increased the neuronal differentiation of LPS-stimulated SVZ NPCs. After screening for multiple signaling pathways, the AKT signaling pathway was found to be involved in EGCG-mediated proliferation and neuronal differentiation of NPCs in vitro. Taken together, our results reveal a previously uncharacterized role of EGCG in the augment of proliferation and neuronal differentiation of SVZ NPCs and subsequent spontaneous recovery after ischemic stroke. Thus, the beneficial effects of EGCG on neurogenesis and stroke recovery should be considered in developing therapeutic approaches.

NQDI-1, an inhibitor of ASK1 attenuates acute perinatal hypoxic-ischemic cerebral injury by modulating cell death

Apoptosis signal-regulating kinase 1 (ASK1) is a ubiquitously expressed protein kinase, which regulates cell fate in numerous injury conditions. Therefore, ASK1 may be a promising novel therapeutic target for injury. However, the expression and distribution of ASK1 in the perinatal brain following hypoxia-ischemia (HI) remains to be elucidated. In the present study, western blotting and immunofluorescence were used to determine the expression and distribution of ASK1 and any associated downstream targets in the perinatal rat brain following HI. NQDI‑1, a specific inhibitor of ASK1 was intracerebroventricularly injected following neonatal rats brain insult for neuroprotection. The results revealed an increased expression of ASK1 and this expression was localized to the neurons and astrocytes, compared with the sham controls. Additionally, it was demonstrated that the ASK1/ c‑Jun N‑terminal kinases (JNK) pathway was involved in the brain damage following HI in neonatal rats. Notably, NQDI‑1 significantly inhibited the in vivo expression levels of ASK1, phosphorylated (p‑)JNK, p‑c‑Jun, p53 and caspase 3. Reduced acute hypoxic‑ischemic cerebral injury and cell apoptosis was observed following the injection of NQDI‑1. Collectively, NQDI-1 attenuated acute perinatal hypoxic‑ischemic cerebral injury by inhibiting the expression of ASK1 and cell apoptosis. This may be a promising novel neuroprotective inhibitor for perinatal cerebra injury.

Optimal concentration and time window for proliferation and differentiation of neural stem cells from embryonic cerebral cortex: 5% oxygen preconditioning for 72 hours

Hypoxia promotes proliferation and differentiation of neural stem cells from embryonic day 12 rat brain tissue, but the concentration and time of hypoxic preconditioning are controversial. To address this, we cultured neural stem cells isolated from embryonic day 14 rat cerebral cortex in 5% and 10% oxygen in vitro. MTT assay, neurosphere number, and immunofluorescent staining found that 5% or 10% oxygen preconditioning for 72 hours improved neural stem cell viability and proliferation. With prolonged hypoxic duration (120 hours), the proportion of apoptotic cells increased. Thus, 5% oxygen preconditioning for 72 hours promotes neural stem cell proliferation and neuronal differentiation. Our findings indicate that the optimal concentration and duration of hypoxic preconditioning for promoting proliferation and differentiation of neural stem cells from the cerebral cortex are 5% oxygen for 72 hours.

Combination cell therapy with mesenchymal stem cells and neural stem cells for brain stroke in rats

Objectives

Brain stroke is the second most important events that lead to disability and morbidity these days. Although, stroke is important, there is no treatment for curing this problem. Nowadays, cell therapy has opened a new window for treating central nervous system disease. In some previous studies the Mesenchymal stem cells and neural stem cells. In this study, we have designed an experiment to assess the combination cell therapy (Mesenchymal and Neural stem cells) effects on brain stroke.

Method and Materials

The Mesenchymal stem cells were isolated from adult rat bone marrow and the neural stem cells were isolated from ganglion eminence of rat embryo 14 days. The Mesenchymal stem cells were injected 1 day after middle cerebral artery occlusion (MCAO) and the neural stem cells transplanted 7 day after MCAO. After 28 days, the neurological outcomes and brain lesion volumes were evaluated. Also, the activity of Caspase 3 was assessed in different groups.

Result

The group which received combination cell therapy had better neurological examination and less brain lesion. Also the combination cell therapy group had the least Caspase 3 activity among the groups.

Conclusions

The combination cell therapy is more effective than Mesenchymal stem cell therapy and neural stem cell therapy separately in treating the brain stroke in rats.

Cortical neurogenesis in adult rats after ischemic brain injury: most new neurons fail to mature

The present study examines the hypothesis that endogenous neural progenitor cells isolated from the neocortex of ischemic brain can differentiate into neurons or glial cells and contribute to neural regeneration. We performed middle cerebral artery occlusion to establish a model of cerebral ischemia/reperfusion injury in adult rats. Immunohistochemical staining of the cortex 1, 3, 7, 14 or 28 days after injury revealed that neural progenitor cells double-positive for nestin and sox-2 appeared in the injured cortex 1 and 3 days post-injury, and were also positive for glial fibrillary acidic protein. New neurons were labeled using bromodeoxyuridine and different stages of maturity were identified using doublecortin, microtubule-associated protein 2 and neuronal nuclei antigen immunohistochemistry. Immature new neurons coexpressing doublecortin and bromodeoxyuridine were observed in the cortex at 3 and 7 days post-injury, and semi-mature and mature new neurons double-positive for microtubule-associated protein 2 and bromodeoxyuridine were found at 14 days post-injury. A few mature new neurons coexpressing neuronal nuclei antigen and bromodeoxyuridine were observed in the injured cortex 28 days post-injury. Glial fibrillary acidic protein/bromodeoxyuridine double-positive astrocytes were also found in the injured cortex. Our findings suggest that neural progenitor cells are present in the damaged cortex of adult rats with cerebral ischemic brain injury, and that they differentiate into astrocytes and immature neurons, but most neurons fail to reach the mature stage.