Carboxypeptidase E/NFα1: a new neurotrophic factor against oxidative stress-induced apoptotic cell death mediated by ERK and PI3-K/AKT pathways

Single-cell transcriptomic and neuropathologic analysis reveals dysregulation of the integrated stress response in progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is a sporadic neurodegenerative tauopathy variably affecting brainstem and cortical structures and characterized by tau inclusions in neurons and glia. The precise mechanism whereby these protein aggregates lead to cell death remains unclear. To investigate the contribution of these different cellular abnormalities to PSP pathogenesis, we performed single-nucleus RNA sequencing and analyzed 45,559 high quality nuclei targeting the subthalamic nucleus and adjacent structures from human post-mortem PSP brains with varying degrees of pathology compared to controls. Cell-type specific differential expression and pathway analysis identified both common and discrete changes in numerous pathways previously implicated in PSP and other neurodegenerative disorders. This included EIF2 signaling, an adaptive pathway activated in response to diverse stressors, which was the top activated pathway in vulnerable cell types. Using immunohistochemistry, we found that activated eIF2α was positively correlated with tau pathology burden in vulnerable brain regions. Multiplex immunofluorescence localized activated eIF2α positivity to hyperphosphorylated tau (p-tau) positive neurons and ALDH1L1-positive astrocytes, supporting the increased transcriptomic EIF2 activation observed in these vulnerable cell types. In conclusion, these data provide insights into cell-type-specific pathological changes in PSP and support the hypothesis that failure of adaptive stress pathways play a mechanistic role in the pathogenesis and progression of PSP.

Hippocampal delivery of neurotrophic factor-α1/carboxypeptidase E gene prevents neurodegeneration, amyloidosis, memory loss in Alzheimer's Disease male mice

Alzheimer's Disease (AD) is a prevalent neurodegenerative disease characterized by tau hyperphosphorylation, Aβ1-42 aggregation and cognitive dysfunction. Therapeutic agents directed at mitigating tau aggregation and clearing Aβ1-42, and delivery of growth factor genes (BDNF, FGF2), have ameliorated cognitive deficits, but these approaches did not prevent or stop AD progression. Here we report that viral-(AAV) delivery of Neurotrophic Factor-α1/Carboxypeptidase E (NF-α1/CPE) gene in hippocampus at an early age prevented later development of cognitive deficits as assessed by Morris water maze and novel object recognition assays, neurodegeneration, and tau hyperphosphorylation in male 3xTg-AD mice. Additionally, amyloid precursor protein (APP) expression was reduced to near non-AD levels, and insoluble Aβ1-42 was reduced significantly. Pro-survival proteins: mitochondrial Bcl2 and Serpina3g were increased; and mitophagy inhibitor Plin4 and pro-inflammatory protein Card14 were decreased in AAV-NF-α1/CPE treated versus untreated AD mice. Thus NF-α1/CPE gene therapy targets many regulatory components to prevent cognitive deficits in 3xTg-AD mice and has implications as a new therapy to prevent AD progression by promoting cell survival, inhibiting APP overexpression and tau hyperphosphorylation.

The Role of Autophagy and Apoptosis in Affected Skin and Lungs in Patients with Systemic Sclerosis

Systemic sclerosis (SSc) is a complex autoimmune inflammatory disorder with multiple organ involvement. Skin changes present the hallmark of SSc and coincide with poor prognosis. Interstitial lung diseases (ILD) are the most widely reported complications in SSc patients and the primary cause of death. It has been proposed that the processes of autophagy and apoptosis could play a significant role in the pathogenesis and clinical course of different autoimmune diseases, and accordingly in SSc. In this manuscript, we review the current knowledge of autophagy and apoptosis processes in the skin and lungs of patients with SSc. Profiling of markers involved in these processes in skin cells can be useful to recognize the stage of fibrosis and can be used in the clinical stratification of patients. Furthermore, the knowledge of the molecular mechanisms underlying these processes enables the repurposing of already known drugs and the development of new biological therapeutics that aim to reverse fibrosis by promoting apoptosis and regulate autophagy in personalized treatment approach. In SSc-ILD patients, the molecular signature of the lung tissues of each patient could be a distinctive criterion in order to establish the correct lung pattern, which directly impacts the course and prognosis of the disease. In this case, resolving the role of tissue-specific markers, which could be detected in the circulation using sensitive molecular methods, would be an important step toward development of non-invasive diagnostic procedures that enable early and precise diagnosis and preventing the high mortality of this rare disease.

Current GMP standards for the production of vaccines and antibodies: An overview

The manufacture of pharmaceutical products made under good manufacturing practices (GMP) must comply with the guidelines of national regulatory bodies based on international or regional compendia. The existence of this type of regulation allows pharmaceutical laboratories to count on the standardization of high-quality production processes, obtaining a safe product for human use, with a positive impact on public health. In addition, the COVID-19 pandemic highlights the importance of having more and better-distributed manufacturing plants, emphasizing regions such as Latin America. This review shows the most important GMP standards in the world and, in particular, their relevance in the production of vaccines and antibodies.

Neurotrophic Factor-α1/Carboxypeptidase E Functions in Neuroprotection and Alleviates Depression

Depression is a major psychiatric disease affecting all ages and is often co-morbid with neurodegeneration in the elderly. Depression and neurodegeneration are associated with decreased neurotrophic factors. In this mini-review the functions and potential therapeutic use of a newly discovered trophic factor, Neurotrophic factor-α1 (NF-α1), also known as Carboxypeptidase E (CPE), in depression and neuroprotection are discussed. NF-α1/CPE expression is enriched in CA3 neurons of the hippocampus. Families carrying null and homozygous non-sense mutations of the NF-α1/CPE gene share common clinical features including childhood onset obesity, type 2 diabetes, impaired intellectual abilities and hypogonadotrophic hypogonadism. Studies in animal models such as CPE knockout (KO) mice and CPEfat/fat mutant mice exhibit similar phenotypes. Analysis of CPE-KO mouse brain revealed that hippocampal CA3 was completely degenerated after weaning stress, along with deficits in hippocampal long-term potentiation. Carbamazepine effectively blocked weaning stress-induced hippocampal CA3 degeneration, suggesting the stress induced epileptic-like neuronal firing led to the degeneration. Analysis of possible mechanisms underlying NF-α1/CPE -mediated neuroprotection revealed that it interacts with the serotonin receptor, 5-HTR1E, and via β arrestin activation, subsequently upregulates ERK1/2 signaling and pro-survival protein, BCL2, levels. Furthermore, the NF-α1/CPE promoter contains a peroxisome proliferator-activated receptor (PPARγ) binding site which can be activated by rosiglitazone, a PPARγ agonist, to up-regulate expression of NF-α1/CPE and neurogenesis, resulting in anti-depression in animal models. Rosiglitazone, an anti-diabetic drug administered to diabetic patients resulted in decline of depression. Thus, NF-α1/CPE is a potential therapeutic agent or drug target for treating depression and neurodegenerative disorders.

Paeoniflorin Rescued MK-801-Induced Schizophrenia-Like Behaviors in Mice via Oxidative Stress Pathway

Schizophrenia (SCZ) affects approximately 1% population worldwide, and the first-line antipsychotics have partial reactivity or non-reactivity with side effects. Therefore, there is an urgent need to find more effective drugs. Paeoniflorin (PF) is the main effective component of traditional Chinese medicine from white peony, red peony and peony bark, which acts as a neuroprotective agent. The purpose of this study was to investigate whether PF can rescue MK-801 induced schizophrenia-like behavior in mice. Our results demonstrated that intragastric administration of PF ameliorated MK-801 induced schizophrenia–like behaviors in mice as demonstrated by prepulse inhibition of acoustic startle response, fear conditioning test for memory and open field test for activity. In contrast, the first-line antipsychotics-olanzapine reversed the prepulse inhibition deficits and hyperactivities, but not memory deficits, in the model mice. Further analysis showed that PF reduced oxidative stress in the MK-801-treated mice, as evidenced by the increased superoxide dismutase levels and decreased malondialdehyde levels in the blood of the model mice. In addition, PF treatment inhibited the expression of the apoptotic protein Bax and restored the expression of tyrosine hydroxylase in the brains of the model mice. in vitro data indicated that PF protected against oxidative stress induced neurotoxicity in the primary cultured hippocampal neurons. In conclusion, our results were the first to provide evidence that PF rescued schizophrenia-like behaviors (both positive symptoms and cognitive impairments) in rodents through oxidative stress pathway, and therefore provide a novel strategy for treatment of SCZ. However, more pre-clinical and clinical research are needed to translate the present findings into clinics for a treatment of schizophrenia.

Addressing Peroxisome Proliferator-Activated Receptor-gamma in 3-Nitropropionic Acid-Induced Striatal Neurotoxicity in Rats

Telmisartan (TEL) is an angiotensin II type 1 receptor blocker and a partial activator of peroxisome proliferator-activated receptor-gamma (PPARγ), which regulates inflammatory and apoptotic pathways. Increasing evidence has demonstrated the PPARγ agonistic property of TEL in several brain disorders. This study aims to explore the neuroprotective impact of TEL in 3-nitropropionic acid (3-NP)-induced neurotoxicity in rats. The PPARγ effect of TEL was affirmed by using the PPARγ agonist pioglitazone (PIO), and the antagonist GW9662. 3-NP led to a significant reduction in body weight alongside motor and cognitive functioning. The striata of the 3-NP-treated rats showed energy-deficit, microglia-mediated inflammatory reactions, apoptotic damage as well as histopathological lesions. PIO and TEL improved motor and cognitive perturbations induced by 3-NP, as confirmed by striatal histopathological examination, energy restoration, and neuronal preservation. Both drugs improved mitochondrial biogenesis evidenced by elevated mRNA expression of PPARγ, PGC-1α, and TFAM, alongside increased striatal ATP and SDH. The mitochondrial effect of TEL was beyond PPARγ activation. As well, their anti-inflammatory effect was attributed to suppression of microglial activation, and protein expression of pS536 p65 NF-κB with marked attenuation of striatal inflammatory mediator's release. Anti-inflammatory cytokine IL-10 expression was concurrently increased. TEL effectively participated in neuronal survival as it promoted phosphorylation of Akt/GSK-3β, further increased Bcl-2 expression, and inhibited cleavage of caspase-3. Interestingly, co-treatment with GW9662 partially revoked the beneficial effects of TEL. These findings recommend that TEL improves motor and cognitive performance, while reducing neuronal inflammation and apoptosis in 3-NP-induced neurotoxicity via a PPARγ-dependent mechanism.

Exosomal Carboxypeptidase E (CPE) and CPE-shRNA-Loaded Exosomes Regulate Metastatic Phenotype of Tumor Cells

Background: Exosomes promote tumor growth and metastasis through intercellular communication, although the mechanism remains elusive. Carboxypeptidase E (CPE) supports the progression of different cancers, including hepatocellular carcinoma (HCC). Here, we investigated whether CPE is the bioactive cargo within exosomes, and whether it contributes to tumorigenesis, using HCC cell lines as a cancer model. Methods: Exosomes were isolated from supernatant media of cancer cells, or human sera. mRNA and protein expression were analyzed using PCR and Western blot. Low-metastatic HCC97L cells were incubated with exosomes derived from high-metastatic HCC97H cells. In other experiments, HCC97H cells were incubated with CPE-shRNA-loaded exosomes. Cell proliferation and invasion were assessed using MTT, colony formation, and matrigel invasion assays. Results: Exosomes released from cancer cells contain CPE mRNA and protein. CPE mRNA levels are enriched in exosomes secreted from high- versus low-metastastic cells, across various cancer types. In a pilot study, significantly higher CPE copy numbers were found in serum exosomes from cancer patients compared to healthy subjects. HCC97L cells, treated with exosomes derived from HCC97H cells, displayed enhanced proliferation and invasion; however, exosomes from HCC97H cells pre-treated with CPE-shRNA failed to promote proliferation. When HEK293T exosomes loaded with CPE-shRNA were incubated with HCC97H cells, the expression of CPE, Cyclin D1, a cell-cycle regulatory protein and c-myc, a proto-oncogene, were suppressed, resulting in the diminished proliferation of HCC97H cells. Conclusions: We identified CPE as an exosomal bioactive molecule driving the growth and invasion of low-metastatic HCC cells. CPE-shRNA loaded exosomes can inhibit malignant tumor cell proliferation via Cyclin D1 and c-MYC suppression. Thus, CPE is a key player in the exosome transmission of tumorigenesis, and the exosome-based delivery of CPE-shRNA offers a potential treatment for tumor progression. Notably, measuring CPE transcript levels in serum exosomes from cancer patients could have potential liquid biopsy applications.

Quercetin Relieves the Excised Great Saphenous Vein Oxidative Damage and Inflammatory Reaction

Objective

The patency and quality of transplanted great saphenous vein (GSV) can seriously influence the physical state and life quality of patients who accepted the coronary artery bypass grafting (CABG). Quercetin is known for antioxidant, antithrombotic, anti-inflammatory, and antitumor properties. In this study, we examined the protection of quercetin to the great saphenous vein from oxidative and inflammatory damage.

Methods

The GSVs were collected from 15 patients undergoing CABG and cultured. Treated the veins by H₂O₂ and detected the NO, SOD, and MDA content by the relevant kits to explore the quercetin protection against oxidative damage. Then, for another group of GSVs, sheared them and detected the inflammatory cytokines, such as IL-6, TNFα, CCL20, PCNA, and VEGF. Collect the veins for H&E staining and PCNA and VEGF immunofluorescent staining.

Results

Pretreatment by quercetin reduced the production of NO and MDA induced by H₂O₂, and increased SOD activity. Quercetin also supressed the mRNA expressions of IL-6, TNFα after mechanical damage and had no influence on CCL20 and VEGF. Consistent with the lower expression of PCNA treated by quercetin, the vein intima was thinner.

Conclusion

These results demonstrated that quercetin protects GSVs by reducing the oxidative damage and inflammatory response and also suppresses the abnormal thickening of venous endothelium by inhibiting cell proliferation. It reminded that, to some extent, quercetin has the potential to release the great saphenous vein graft damage.

Carboxypeptidase E Independently Changes Microtubule Glutamylation, Dendritic Branching, and Neuronal Migration

Neuronal migration and dendritogenesis are dependent on dynamic changes to the microtubule (MT) network. Among various factors that regulate MT dynamics and stability, post-translational modifications (PTMs) of MTs play a critical role in conferring specificity of regulatory protein binding to MTs. Thus, it is important to understand the regulation of PTMs during brain development as multiple developmental processes are dependent on MTs. In this study, we identified that carboxypeptidase E (CPE) changes tubulin polyglutamylation, a major PTM in the brain, and we examine the impact of CPE-mediated changes to polyglutamylation on cortical neuron migration and dendrite morphology. We show, for the first time, that overexpression of CPE increases the level of polyglutamylated α-tubulin while knockdown decreases the level of polyglutamylation. We also demonstrate that CPE-mediated changes to polyglutamylation are dependent on the CPE zinc-binding motif and that this motif is necessary for CPE action on p150^Glued localization. However, overexpression of a CPE mutant that does not increase MT glutamylation mimics the effects of overexpression of wild type CPE on dendrite branching. Furthermore, although overexpression of wild type CPE does not alter cortical neuron migration, overexpression of the mutant may act in a dominant-negative manner as it decreases the number of neurons that reach the cortical plate (CP), as we previously reported for CPE knockdown. Overall, our data suggest that CPE changes MT glutamylation and redistribution of p150^Glued and that this function of CPE is independent of its role in shaping dendrite development but plays a partial role in regulating cortical neuron migration.

Novel interaction between neurotrophic factor-α1/carboxypeptidase E and serotonin receptor, 5-HTR1E, protects human neurons against oxidative/neuroexcitotoxic stress via β-arrestin/ERK signaling

Protecting neurons from death during oxidative and neuroexcitotoxic stress is key for preventing cognitive dysfunction. We uncovered a novel neuroprotective mechanism involving interaction between neurotrophic factor-α1 (NF-α1/carboxypeptidase E, CPE) and human 5-HTR1E, a G protein-coupled serotonin receptor with no previously known neurological function. Co-immunoprecipitation and pull-down assays confirmed interaction between NFα1/CPE and 5-HTR1E and 125I NF-α1/CPE-binding studies demonstrated saturable, high-affinity binding to 5-HTR1E in stably transfected HEK293 cells (Kd = 13.82 nM). Treatment of 5-HTR1E stable cells with NF-α1/CPE increased pERK 1/2 and pCREB levels which prevented a decrease in pro-survival protein, BCL2, during H2O2-induced oxidative stress. Cell survival assay in β-arrestin Knockout HEK293 cells showed that the NF-α1/CPE-5-HTR1E-mediated protection against oxidative stress was β-arrestin-dependent. Molecular dynamics studies revealed that NF-α1/CPE interacts with 5-HTR1E via 3 salt bridges, stabilized by several hydrogen bonds, independent of the serotonin pocket. Furthermore, after phosphorylating the C-terminal tail and intracellular loop 3 (ICL3) of NF-α1/CPE-5-HTR1E, it recruited β-arrestin1 by forming numerous salt bridges and hydrogen bonds to ICL2 and ICL3, leading to activation of β-arrestin1. Immunofluorescence studies showed 5-HTR1E and NF-α1/CPE are highly expressed and co-localized on cell surface of human hippocampal neurons. Importantly, knock-down of 5-HTR1E in human primary neurons diminished the NF-α1/CPE-mediated protection of these neurons against oxidative stress and glutamate neurotoxicity-induced cell death. Thus, NF-α1/CPE uniquely interacts with serotonin receptor 5-HTR1E to activate the β-arrestin/ERK/CREB/BCL2 pathway to mediate stress-induced neuroprotection.

BDV Syndrome: An Emerging Syndrome With Profound Obesity and Neurodevelopmental Delay Resembling Prader-Willi Syndrome

CONTEXT

CPE encodes carboxypeptidase E, an enzyme that converts proneuropeptides and propeptide hormones to bioactive forms. It is widely expressed in the endocrine and central nervous system. To date, 4 individuals from 2 families with core clinical features including morbid obesity, neurodevelopmental delay, and hypogonadotropic hypogonadism, harboring biallelic loss-of-function (LoF) CPE variants, have been reported.

OBJECTIVE

We describe 4 affected individuals from 3 unrelated consanguineous families, 2 siblings of Syrian, 1 of Egyptian, and 1 of Pakistani descent, all harboring novel homozygous CPE LoF variants.

METHODS

After excluding Prader-Willi syndrome (PWS), exome sequencing was performed in both Syrian siblings. The variants identified in the other 2 individuals were reported as research variants in a large-scale exome study and in the ClinVar database. Computational modeling of all possible missense alterations allowed assessing CPE tolerance to missense variants.

RESULTS

All affected individuals were severely obese with neurodevelopmental delay and other endocrine anomalies. Three individuals from 2 families shared the same CPE homozygous truncating variant c.361C > T, p.(Arg121*), while the fourth carried the c.994del, p.(Ser333Alafs*22) variant. Comparison of clinical features with previously described cases and standardization according to the Human Phenotype Ontology terms indicated a recognizable clinical phenotype, which we termed Blakemore-Durmaz-Vasileiou (BDV) syndrome. Computational analysis indicated high conservation of CPE domains and intolerance to missense changes.

CONCLUSION

Biallelic truncating CPE variants are associated with BDV syndrome, a clinically recognizable monogenic recessive syndrome with childhood-onset obesity, neurodevelopmental delay, hypogonadotropic hypogonadism, and hypothyroidism. BDV syndrome resembles PWS. Our findings suggest missense variants may also be clinically relevant.

A New Cause of Obesity Syndrome Associated with a Mutation in the Carboxypeptidase Gene Detected in Three Siblings with Obesity, Intellectual Disability and Hypogonadotropic Hypogonadism

OBJECTIVE

Carboxypeptidase E (CPE) plays a critical role in the biosynthesis of peptide hormones and neuropeptides in the endocrine system and central nervous system. CPE knockout mice models exhibit disorders such as diabetes, hyperproinsulinaemia, low bone mineral density and neurodevelopmental disorders. Only one patient is described with morbid obesity, intellectual disability, abnormal glucose homeostasis and hypogonadotropic hypogonadism, which was associated with a homozygous frameshift deletion in CPE.

METHODS

Herein are described three siblings with obesity, intellectual disability and hypogonadotropic hypogonadism. Whole exome sequencing (WES) was performed in the index case. Candidate variants were prioritised and segregation of the variant, consistent with the phenotype of the index case, was assessed by Sanger sequencing in affected siblings and parents.

RESULTS

WES analysis revealed a homozygous nonsense c.405C>A (p.Y135*) mutation in CPE. Validation and segregation analysis confirmed the homozygous mutation in the index case and his affected siblings. The parents were phenotypically normal heterozygous mutation carriers.

CONCLUSION

This study provides additional evidence of the association between a homozygous nonsense mutation in CPE and a clinical phenotype consisting of obesity, intellectual disability and hypogonadotropic hypogonadism, which may be considered as a new monogenic obesity syndrome.

Neurotrophic factor-α1, a novel tropin is critical for the prevention of stress-induced hippocampal CA3 cell death and cognitive dysfunction in mice: comparison to BDNF

Stress leads to brain pathology including hippocampal degeneration, cognitive dysfunction, and potential mood disorders. Hippocampal CA3, a most stress-vulnerable region, consists of pyramidal neurons that regulate cognitive functions e.g. learning and memory. These CA3 neurons express high levels of the neuroprotective protein, neurotrophic factor-α1 (NF-α1), also known as carboxypeptidase E (CPE), and receive contacts from granule cell projections that release BDNF which has neuroprotective activity. Whether NF-α1-CPE and/or BDNF are critical in protecting these CA3 neurons against severe stress-induced cell death is unknown. Here we show that social combined with the physical stress of maternal separation, ear tagging, and tail snipping at weaning in 3-week-old mice lacking NF-α1-CPE, led to complete hippocampal CA3 degeneration, despite having BDNF and active phosphorylated TrkB receptor levels similar to WT animals. Mice administered TrkB inhibitor, ANA12 which blocked TrkB phosphorylation showed no degeneration of the CA3 neurons after the weaning stress paradigm. Furthermore, transgenic knock-in mice expressing CPE-E342Q, an enzymatically inactive form, replacing NF-α1-CPE, showed no CA3 degeneration and exhibited normal learning and memory after the weaning stress, unlike NF-α1-CPE-KO mice. Mechanistically, we showed that radio-labeled NF-α1-CPE bound HT22 hippocampal cells in a saturable manner and with high affinity (Kd = 4.37 nM). Subsequently, treatment of the HT22^cpe-/- cells with NF-α1-CPE or CPE-E342Q equivalently activated ERK signaling and increased BCL2 expression to protect these neurons against H₂O₂-or glutamate-induced cytotoxicity. Our findings show that NF-α1-CPE is more critical compared to BDNF in protecting CA3 pyramidal neurons against stress-induced cell death and cognitive dysfunction, independent of its enzymatic activity.

Nonenzymatic and Trophic Activities of Carboxypeptidase E Regulate Bone Mass and Bioenergetics of Skeletal Stem Cells in Mice

Bone and energy metabolism are integrated by common regulatory mechanisms. Carboxypeptidase E (CPE), also known as obesity susceptibility protein or neurotrophic factor‐α1, is recognized for its function in processing prohormones, including proinsulin and pro‐opiomelanocortin polypeptide. Independent of its enzymatic activity, CPE may also act as a secreted factor with divergent roles in neuroprotection and cancer growth; however, its role in the regulation of bone mass and skeletal cell differentiation is unknown. Male mice with global deficiency in CPE are characterized with profound visceral obesity, low bone mass in both appendicular and axial skeleton, and high volume of marrow fat. Interestingly, although metabolic deficit of CPE KO mice develops early in life, bone deficit develops in older age, suggesting that CPE bone‐specific activities differ from its enzymatic activities. Indeed, mutated CPE knockin (mCPE KI) mice ectopically expressing CPE‐E342Q, a mutated protein lacking enzymatic activity, develop the same obese phenotype and accumulate the same volume of marrow fat as CPE KO mice, but their bone mass is normal. In addition, differentiation of marrow hematopoietic cells toward tartrate‐resistant acid phosphatase‐positive multinucleated osteoclasts is highly increased in CPE KO mice, but normal in mCPE KI mice. Moreover, in murine skeletal stem cells, nonenzymatic trophic CPE has activated ERK signaling, increased cell proliferation and increased mitochondrial activity. Treatment of preosteoblastic cells with intact or mutated recombinant CPE led to a transient accumulation of small lipid droplets, increased oxidative phosphorylation, and increased cellular dependence on fatty acids as fuel for energy production. In human marrow aspirates, CPE expression increases up to 30‐fold in osteogenic conditions. These findings suggest that nonenzymatic and trophic activities of CPE regulate bone mass, whereas marrow adiposity is controlled by CPE enzymatic activity. Thus, CPE can be positioned as a factor regulating simultaneously bone and energy metabolism through a combination of shared and distinct mechanisms. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Norcepharadione B attenuates H2O2-induced neuronal injury by upregulating cellular antioxidants and inhibiting volume-sensitive Cl- channel

Oxidative stress acts as an essential culprit factor in the development of stroke and Alzheimer’s disease. Norcepharadione B possesses various pharmacologic features as an extract obtained from Houttuynia cordata. Nevertheless, the anti-apoptotic and neuroprotective characteristics of norcepharadione B remain unclear. In this study, the neuronal protection effect provided by norcepharadione B against injury caused by hydrogen peroxide (H2O2) in HT22 cell as well as the fundamental mechanism was systematically explored. The neurotoxicity assays of hippocampal cells, which were co-cultured with H2O2, showed that norcepharadione B had the ability to insulate the toxicity induced by H2O2 with significant reduced cell apoptosis. Besides, norcepharadione B potentiated the activity of superoxide dismutase (SOD), increased the level of glutathione (GSH), and decreased malondialdehyde content. The H2O2-induced apoptotic protein Bax was suppressed, and the anti-apoptotic protein Bcl-2 was boosted by norcepharadione B. Norcepharadione B promoted Akt phosphorylation and further upregulated heme oxygenase (HO-1) in cells exposed to oxidative stress. However, the inductive effect of HO-1 by norcepharadione B was shut off via the PI3K/Akt inhibitor LY294002. Furthermore, 2-h incubation with H2O2 substantially increased cell volume in HT22 cells, while norcepharadione B effectively alleviated such effect by interrupting the activation of VSOR Cl− channel. Collectively, our data revealed protective properties of norcepharadione B in resisting oxidative stress induced by H2O2 through elevation of HO-1 in the dependence of PI3K/Akt and in inhibiting H2O2-induced cell swelling by VSOR Cl− channel obstruction in HT22 cells.

Impact statement

Norcepharadione B is an aporphine alkaloid compound extracted from Chinese herb Houttuynia cordata. It was well known for its anti-inflammatory, anti-cancer, and anti-platelet aggregation outcomes. Our study demonstrated that Norcepharadione B protected hippocampal neurons against oxidative stress and the resultant cell apoptosis upon H2O2 exposure. Meanwhile, Norcepharadione B also substantially reduced cell swelling induced by H2O2 via inhibiting VSOR Cl− channel in neurons. These findings uncovered the potential mechanisms of Norcepharadione B in protecting neuron apoptosis under oxidative stress and propose that Norcepharadione B may serve as a favorable herb medicine for restoring neuronal injury in the pathogenesis of stroke together with other neurodegenerative diseases.

Downregulation of CPA4 inhibits non small-cell lung cancer growth by suppressing the AKT/c-MYC pathway

Carboxypeptidase A4 (CPA4) is a member of the metallocarboxypeptidase family. A previous study indicated that CPA4 may participate in the modulation of peptide hormone activity and hormone-regulated tissue growth and differentiation. However, the role of CPA4 in lung tumorigenesis remains unclear. Our study revealed that CPA4 expression was higher in both lung cancer cells and tumor tissues. We performed 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assays, colony-formation assays, and Cellomics ArrayScan Infinity analysis to demonstrate that CPA4 knockdown inhibited non small-cell lung cancer (NSCLC) cell proliferation. Conversely, ectopic expression of CPA4 enhanced lung cancer cell proliferation. Consistent with these observations, we generated xenograft tumor models to confirm that CPA4 downregulation suppressed NSCLC cell growth. Mechanistically, we revealed that CPA4 downregulation may induce apoptosis and G1-S arrest by suppressing the protein kinase B/c-MYC pathway. These results suggest that CPA4 has an oncogenic effect on lung cancer growth. Taken together, we identified a novel gene in lung cancer that might provide a basis for new therapeutic targets.

Shengmai injection alleviates H2O2‑induced oxidative stress through activation of AKT and inhibition of ERK pathways in neonatal rat cardiomyocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Shengmai injection (SMI) is a classical traditional Chinese medicine (TCM) officially recorded in Pharmacopoeia of the People's Republic of China (version 2015) and has long been used to treat heart failure in China. However scientific evidence for the anti-oxidative stress potential of SMI used in traditional medicine is lacking.

AIM OF STUDY

The present study aimed to evaluate the efficacy of SMI in alleviating H₂O₂‑induced Oxidative Stress the underlying mechanisms MATERIALS AND METHODS: H₂O₂-induced oxidative stress model of cardiomyocytes was established with primary cultured neonatal rat cardiomyocytes. CCK8 cell viability assay and lacatate dehydrogenase cytotoxicity assay were performed to ensure the safety dose and lowest effective dose for the mode employing CCK-8 cell viability assay kit and lactate dehydrogenase cytotoxicity assay kit. ROS levels were determined using CM-H2DCFDA fluorescent probe in cardiomyocytes with H₂O₂-induced oxidative stress. The change of NAD(P)H level in cardiomyocytes was evaluated during the process of oxidative stress. The content of myocardial cytosolic Ca²⁺ and Ca²⁺ was determined using Fura-2/AM and Rhod 2-AM fluorescent probe in mitochondrial in the process of oxidative stress. Annexin V-FITC/PI double staining was applied to examine the apoptotic cells in cardiomyocytes with oxidative stress. To identify the apoptosis after oxidative stress myocardial cells with the application of Annexin V-FITC/PI double staining apoptosis detection kit. Quantitative polymerase chain reaction (RT-PCR) was applied to measure the expression of antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GSR). Western blot was performed to observe the phosphorylation of AKT and ERK1/2.

RESULTS

SMI was shown to significantly attenuate oxidative stress-induced cell proliferation arrest and apoptosis in neonatal rat cardiomyocytes. In addition, SMI treatment could decrease the production of reactive oxygen species (ROS), nicotinamide adenine dinucleotide (NADH) and malondialdehyde (MDA), and reduce the overloads of cytoplasmic Ca²⁺ and mitochondrial Ca²⁺ induced by H₂O₂. SMI could also restore the mRNA expression and activities of SOD, GSR, and CAT suppressed by H₂O₂. Mechanistically, SMI upregulated intracellular AKT phosphorylation and downregulate ERK1/2 phosphorylation in H₂O₂-treated cardiomyocytes. Pretreatment with LY294002, an AKT phosphorylation inhibitor, suppressed the protective role of SMI in cardiomyocytes, while pretreatment with PD98059, an ERK1/2 phosphorylation inhibitor, enhanced the effect of SMI.

CONCLUSIONS

In conclusion, SMI may attenuate oxidative stress-induced damage in cardiomyocytes potentially through the AKT and ERK1/2 pathway and can function as a promising injectable traditional Chinese medicine to treat oxidative stress-induced injury.

Neurotrophic, Gene Regulation, and Cognitive Functions of Carboxypeptidase E-Neurotrophic Factor-α1 and Its Variants

Carboxypeptidase E, also known as neurotrophic factor-α1 (CPE-NFα1), was first discovered as an exopeptidase and is known to work by cleaving C-terminal basic amino acids from prohormone intermediates to produce mature peptide hormones and neuropeptides in the endocrine and central nervous systems, respectively. CPE-NFα1 also plays a critical role in prohormone sorting and secretory vesicle transportation. Recently, emerging studies have indicated that CPE-NFα1 exerts multiple non-enzymatic physiological roles in maintaining normal central nervous system function and in neurodevelopment. This includes potent neuroprotective and anti-depressant activities, as well as stem cell differentiation functions. In addition, N-terminal truncated variants of CPE-NFα1 have been identified to regulate expression of important neurodevelopmental genes. This mini-review summarizes recent advances in understanding the mechanisms underlying CPE-NFα1’s function in neuroprotection during stress and aspects of neurodevelopment.

Roles of ERK1/2 and PI3K/AKT signaling pathways in mitochondria-mediated apoptosis in testes of hypothyroid rats

The absence of the thyroid hormone (TH) could impair testicular function, but its mechanism is still rudimentary. This study aims to explore the roles of estrogen receptor (ER α, β) and G protein-coupled receptor 30 (GPR30), extracellular signal regulated kinase (ERK1/2) and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathways in apoptosis in testes of hypothyroidism rats. Male Wistar rats were randomly divided into control (C), low-(L) and high-hypothyroidism (H) groups [1 mL per 100 g BW per day normal saline, 0.001% and 0.1% propylthiouracil (PTU), respectively] by intragastrical gavage for 60 days. The levels of triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) in serum were measured. Expressions of ERα, ERβ and GPR30, pathway related protein expressions of ERK1/2 and PI3 K/AKT and apoptosis were detected in testicular homogenates. The results showed that T3 and T4 levels were decreased, and the TSH level was increased significantly in the H group. Protein expressions of ERα, ERβ and GPR30 decreased significantly in the H group. Significantly decreased protein expressions of p-ERK1/2, p-PI3K p85, p-AKT Ser473, Ras, p-Raf-1 Ser259, p-Raf-1 Ser338 and cyclin D1 in L and H groups as well PI3K p85, p-AKT and Thr308 in the H group were observed. Moreover, there was a significant increase in the Bad protein expression in L and H groups. In addition, there was a significant increase in the expression of Bax/Bcl-2, caspase 9 and cleaved caspase 3 and a significant decrease in the total caspase 3 protein expression in the H group. These results suggested that ERK1/2 and PI3K/AKT signaling pathways could be suppressed by hypothyroidism via inhibiting the expressions of ERs and could finally induce apoptosis in testes.

2,3,5,4'-Tetrahydroxystilbene-2-O-beta-D-glucoside Reverses Stress-Induced Depression via Inflammatory and Oxidative Stress Pathways

Major depressive disorder (MDD) is a chronic mental disease that adversely affects human mood and cognition. Many first-line antidepressant drugs have high rates of partial responsiveness or nonresponsiveness with side effects, and finding more effective drugs for the treatment of depression is therefore urgently needed. THSG, a main active compound of the traditional Chinese herb Polygonum multiflorum, reportedly acts as a neuroprotective agent. This study aimed to illustrate whether THSG prevents depressive-like behaviors induced by chronic restraint stress (CRS) in an MDD mouse model. Our results demonstrated that the peripheral administration of different THSG doses (10 mg/kg, 20 mg/kg, and 40 mg/kg) reversed the depressive-like behaviors in CRS mice as measured by the tail suspension test, forced swimming test, and open-field test. Further analyses suggested that THSG treatment reduced oxidative stress in both the central and peripheral nervous systems of CRS mice. In addition, heightened inflammatory responses, demonstrated by the increased expression of proinflammatory factors (TNF-α, IL-1β, and IL-6), in hippocampal and prefrontal cortex tissues of CRS mice were inhibited by THSG administration. THSG also restored the diminished Akt signaling pathway in the brains of CRS mice. Moreover, our data suggest increased astrocyte proliferation and neurogenesis in the hippocampus of CRS mice after THSG treatment. Taken together, our results demonstrated an antidepressant effect of THSG in a mouse model of MDD for the first time, and oxidative stress and inflammatory pathways were determined to play roles in this effect.

Cloning, gene regulation, and neuronal proliferation functions of novel N-terminal-truncated carboxypeptidase E/neurotrophic factor-αl variants in embryonic mouse brain

Carboxypeptidase E (CPE), an exopeptidase involved in proneuropeptide processing, is also a neurotrophic factor, named neurotrophic factor-α1 (NF-α1) and has important roles in neuroprotection, stem cell differentiation, and neurite outgrowth, independent of enzymatic activity. Additionally, an N-terminal-truncated CPE/NF-α1 variant, (CPE/NF-α1)-ΔN, proposed from bioinformatic analysis of GenBank (National Center for Biotechnology Information, Bethesda, MD, USA) DNA sequences and encoding a 40-kDa protein, has been found to be exclusively expressed in embryonic neurons. To investigate the function of (CPE/NF-α1)-ΔN in neurodevelopment, we first cloned (CPE/NF-α1)-ΔN transcripts from an embryonic mouse brain. A rapid amplification of cDNA ends assay, DNA sequencing, and Northern blot revealed 1.9- and 1.73-kb transcripts, which encoded 47- and 40-kDa (CPE/NF-α1)-ΔN proteins, respectively. Those proteins were expressed in embryonic mouse brain. Expression of the 2 (CPE/NF-α1)-ΔN mRNAs surged at embryonic d 10.5, correlating with the time of neurogenesis in the developing brain and also at postnatal d 1. HT22 cells, a mouse hippocampal cell line, transduced with 40 kDa (CPE/NF-α1)-ΔN up-regulated expression of genes involved in embryonic neurodevelopment: insulin-like growth factor binding protein 2 ( IGFBP2), death-associated protein 1, and ephrin A1, which regulate proliferation, programmed cell death, and neuronal migration, respectively. HT22 cells and embryonic cortical neurons overexpressing 40 kDa (CPE/NF-α1)-ΔN exhibited enhanced proliferation, which was inhibited by IGFBP2 short interfering RNA treatment. Thus, 40 kDa (CPE/NF-α1)-ΔN has an important, enzymatically independent role in the regulation of genes critical for neurodevelopment.-Xiao, L., Yang, X., Sharma, V. K., Loh, Y. P. Cloning, gene regulation, and neuronal proliferation functions of novel N-terminal-truncated carboxypeptidase E/neurotrophic factor-αl variants in embryonic mouse brain.

Human brain gene expression profiles of the cathepsin V and cathepsin L cysteine proteases, with the PC1/3 and PC2 serine proteases, involved in neuropeptide production

Proteases are required to generate active peptide neurotransmitters, known as neuropeptides, from pro-neuropeptides. Model animal systems have recently illustrated roles for the cathepsin V (CTSV) and cathepsin L (CTSL) cysteine proteases, combined with the serine proteases PC1/3 (PCSK1) and PC2 (PCSK2), and exopeptidases in the production of neuropeptides. There is notable interest in the human-specific cathepsin V gene which is not present in rodent and other animal models used in prior studies of neuropeptide production. A gap in the field is knowledge of the human brain gene expression patterns of these neuropeptide-producing protease systems. Therefore, the goal of this study was to characterize the expression profiles of these pro-neuropeptide processing proteases in human brain. Quantitative gene expression microarray data for 169 human brain regions was obtained from the Allen Institute Human Brain Atlas resource, analyzed as log₂ of gene expression intensity normalized to the mean of human genes (21,245 genes) expressed in human brain. These proteases had log₂ values of 2–12, indicating expression levels above the average of all genes in the human brain, with varying expression levels among the 169 brain regions. CTSV and CTSL displayed moderate to high expression values of 1.9–8.6 and 7.1–10.6, respectively. Interestingly, CTSV and CTSL showed high expression in white matter composed of myelinated axons, consistent with the knowledge that neuropeptide production occurs in axons within transported neuropeptide secretory vesicles to nerve terminals. PCSK1 had a broad range of moderate to very high expression with log₂ of 2–12. PCSK2 had somewhat lower expression levels than PCSK1. The exopeptidase genes RNPEP, CTSH, and CPE each showed fairly even levels of expression throughout the brain, with CPE displaying high expression. The prevalence of these processing proteases throughout human brain regions, including areas rich in neuropeptides such as hypothalamus, is consistent with their roles for neuropeptide production. Further, proenkephalin and NPY precursors, substrates of CTSV and CTSL shown in prior model animal studies, were co-expressed with CTSV and CTSL. These data demonstrate that the human brain expresses the neuropeptide-producing cysteine and serine proteases, with exopeptidases, throughout a multitude of brain regions.

Mitogen- and Stress-Activated Protein Kinase 1 Regulates Status Epilepticus-Evoked Cell Death in the Hippocampus

Mitogen-activated protein kinase (MAPK) signaling has been implicated in a wide range of neuronal processes, including development, plasticity, and viability. One of the principal downstream targets of both the extracellular signal-regulated kinase/MAPK pathway and the p38 MAPK pathway is Mitogen- and Stress-activated protein Kinase 1 (MSK1). Here, we sought to understand the role that MSK1 plays in neuroprotection against excitotoxic stimulation in the hippocampus. To this end, we utilized immunohistochemical labeling, a MSK1 null mouse line, cell viability assays, and array-based profiling approaches. Initially, we show that MSK1 is broadly expressed within the major neuronal cell layers of the hippocampus and that status epilepticus drives acute induction of MSK1 activation. In response to the status epilepticus paradigm, MSK1 KO mice exhibited a striking increase in vulnerability to pilocarpine-evoked cell death within the CA1 and CA3 cell layers. Further, cultured MSK1 null neurons exhibited a heighted level of N-methyl-D-aspartate-evoked excitotoxicity relative to wild-type neurons, as assessed using the lactate dehydrogenase assay. Given these findings, we examined the hippocampal transcriptional profile of MSK1 null mice. Affymetrix array profiling revealed that MSK1 deletion led to the significant (>1.25-fold) downregulation of 130 genes and an upregulation of 145 genes. Notably, functional analysis indicated that a subset of these genes contribute to neuroprotective signaling networks. Together, these data provide important new insights into the mechanism by which the MAPK/MSK1 signaling cassette confers neuroprotection against excitotoxic insults. Approaches designed to upregulate or mimic the functional effects of MSK1 may prove beneficial against an array of degenerative processes resulting from excitotoxic insults.

Loss of scinderin decreased expression of epidermal growth factor receptor and promoted apoptosis of castration-resistant prostate cancer cells

Most patients with prostate cancer will eventually develop the castration-resistant form characterised by metastasis. Cytoskeleton constituents, including F-actin, play important roles in maintaining epithelial integrity and their disruption is a major cause of cancer progression. We previously showed that scinderin (SCIN), an important regulator of F-actin organisation, is highly expressed in poorly differentiated cancer tissues. This study aimed to explore the mechanism of its regulation of cell proliferation. We discovered that SCIN knockdown significantly downregulated epidermal growth factor receptor (EGFR) protein expression, and inhibited epidermal growth factor (EGF)-mediated cell proliferation and activation of the downstream mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signalling pathway. Silencing of SCIN promoted apoptosis in two cell lines (PC-3 and DU145), inhibited B-cell lymphoma-extra-large (Bcl-xl) expression and activated caspase signalling. Furthermore, in vivo studies showed that SCIN deletion slowed tumour growth and decreased EGFR expression. Thus, we conclude that SCIN promotes prostate cancer cell survival by stabilising EGFR and MEK/ERK signalling.

Effects of soluble CPE on glioma cell migration are associated with mTOR activation and enhanced glucose flux

Carboxypeptidase E (CPE) has recently been described as a multifunctional protein that regulates proliferation, migration and survival in several tumor entities. In glioblastoma (GBM), the most malignant primary brain tumor, secreted CPE (sCPE) was shown to modulate tumor cell migration. In our current study, we aimed at clarifying the underlying molecular mechanisms regulating anti-migratory as well as novel metabolic effects of sCPE in GBM. Here we show that sCPE activates mTORC1 signaling in glioma cells detectable by phosphorylation of its downstream target RPS6. Additionally, sCPE diminishes glioma cell migration associated with a negative regulation of Rac1 signaling via RPS6, since both inhibition of mTOR and stimulation of Rac1 results in a reversed effect of sCPE on migration. Knockdown of CPE leads to a decrease of active RPS6 associated with increased GBM cell motility. Apart from this, we show that sCPE enhances glucose flux into the tricarboxylic acid cycle at the expense of lactate production, thereby decreasing aerobic glycolysis, which might as well contribute to a less invasive behavior of tumor cells. Our data contributes to a better understanding of the complexity of GBM cell migration and sheds new light on how tumor cell invasion and metabolic plasticity are interconnected.

Dissecting carboxypeptidase E: properties, functions and pathophysiological roles in disease

Since discovery in 1982, carboxypeptidase E (CPE) has been shown to be involved in the biosynthesis of a wide range of neuropeptides and peptide hormones in endocrine tissues, and in the nervous system. This protein is produced from pro-CPE and exists in soluble and membrane forms. Membrane CPE mediates the targeting of prohormones to the regulated secretory pathway, while soluble CPE acts as an exopeptidase and cleaves C-terminal basic residues from peptide intermediates to generate bioactive peptides. CPE also participates in protein internalization, vesicle transport and regulation of signaling pathways. Therefore, in two types of CPE mutant mice, Cpe^fat/Cpe^fat and Cpe knockout, loss of normal CPE leads to a lot of disorders, including diabetes, hyperproinsulinemia, low bone mineral density and deficits in learning and memory. In addition, the potential roles of CPE and ΔN-CPE, an N-terminal truncated form, in tumorigenesis and diagnosis were also addressed. Herein, we focus on dissecting the pathophysiological roles of CPE in the endocrine and nervous systems, and related diseases.

Absence of Carboxypeptidase E/Neurotrophic Factor-Α1 in Knock-Out Mice Leads to Dysfunction of BDNF-TRKB Signaling in Hippocampus

Carboxypeptidase E (CPE), first discovered as a prohormone processing enzyme, has also now been shown to be a secreted neurotrophic factor (neurotrophic factor-α1, NF-α1) that acts extracellularly as a signaling molecule to mediate neuroprotection, cortical stem cell differentiation, and antidepressive-like behavior in mice. Since brain-derived neurotrophic factor (BDNF) has very similar trophic functions, and its processing from pro-BDNF involves intracellular sorting of pro-BDNF to the regulated secretory pathway by CPE acting as a sorting receptor, we investigated whether the lack of CPE/NF-α1 would affect BDNF-TrkB signaling in mice. Previous studies have shown that CPE/NF-α1 knock-out (KO) mice exhibited severe neurodegeneration of the hippocampal CA3 region which raises the question of why other neurotrophic factors such as BDNF could not compensate for the deficiency of CPE. Here, we show that the expressions of pro-BDNF mRNA and protein in hippocampus of CPE-KO mice were similar to WT mice, but mature BDNF was ∼40% less in the CPE-KO mice, suggesting decreased intracellular processing of pro-BDNF. Furthermore, TrkB receptor levels were similar in both genotypes, but there was significantly decreased phosphorylation of TrkB receptor in the CPE-KO mice. Electrophysiological studies showed lack of formation of long-term potentiation in hippocampal slices of CPE-KO mice compared to WT mice, which was not rescued by application of BDNF, indicating dysfunction of the BDNF-TrkB signaling system. The CPE-KO mice showed normal postsynaptic AMPA response to kainate application in hippocampal slices and dissociated neurons. Our findings indicate that CPE/NF-α1 is essential for normal BDNF-TrkB signaling function in mouse hippocampus.

A Novel Single Nucleotide T980C Polymorphism in the Human Carboxypeptidase E Gene Results in Loss of Neuroprotective Function

Report of a human with a homozygous truncating null mutation of the Carboxypeptidase E (CPE) gene with endocrinological and neurological deficits prompted us to search for other mutations in the human CPE gene that might be linked to disease. We searched an EST database and identified from a small population of patients, a novel T to C single nucleotide polymorphism (SNP) in the CPE gene at bp980 of exon 4, herein called TC-CPE. This introduces a tryptophan to arginine (W235R) mutation in the catalytic domain of human CPE protein. Over-expression of TC-CPE in N2A cells, a neuroendocrine cell line, showed that it was synthesized, but was found in lesser amounts compared to over-expressed WT-CPE in these cells. Furthermore, TC-CPE was secreted poorly from these N2A cells. The levels of TC-CPE were significantly increased after the N2A cells were treated with MG132 (a proteasome inhibitor), suggesting that TC-CPE was targeted to proteasomes for degradation in N2A cells. In addition, TC-CPE induced ER stress as demonstrated by the increased expression of CHOP in N2A cells. Double labeling of CPE and calnexin (and ER marker) suggested the accumulation of TC-CPE in the ER, and the accumulation appears to be enhanced by the treatment of MG132 in the cells. Moreover, the secreted levels of TC-CPE were not affected by the treatment of MG132 in the cells. Over-expression studies revealed that while N2A cells transfected with WT-CPE showed reduced cytotoxicity when challenged with H₂O₂ compared to cells expressing an empty vector, cells transfected with TC-CPE had no effect. Furthermore, WT-CPE condition medium showed protective effect against oxidative stress, but not TC-CPE condition medium. Although co-expression of WT-CPE and TC-CPE in N2A cells resulted in the reduction in secretion of WT-CPE, co-expression of WT-CPE and TC-CPE did not significantly affect the protective effect of WT-CPE. Taken together, we have identified a novel SNP in the CPE gene which results in the loss of its neuroprotective function in cells and may confer neurological disorders in humans.

Neuroserpin Attenuates H2O2-Induced Oxidative Stress in Hippocampal Neurons via AKT and BCL-2 Signaling Pathways

Oxidative stress plays a critical role in neuronal injury and is associated with various neurological diseases. Here, we explored the potential protective effect of neuroserpin against oxidative stress in primary cultured hippocampal neurons. Our results show that neuroserpin inhibits H2O2-induced neurotoxicity in hippocampal cultures as measured by WST, LDH release, and TUNEL assays. We found that neuroserpin enhanced the activation of AKT in cultures subjected to oxidative stress and that the AKT inhibitor Ly294002 blocked this neuroprotective effect. Neuroserpin increased the expression of the anti-apoptotic protein BCL-2 and blocked the activation of caspase-3. Neuroserpin did not increase the level of neuroprotection over levels seen in neurons transduced with a BCL-2 expression vector, and an inhibitor of Trk receptors, K252a, did not block neuroserpin's effect. Taken together, our study demonstrates that neuroserpin protects against oxidative stress-induced dysfunction and death of primary cultured hippocampal neurons through the AKT-BCL-2 signaling pathway through a mechanism that does not involve the Trk receptors and leads to inhibition of caspase-3 activation.

Quercetin attenuates high fructose feeding-induced atherosclerosis by suppressing inflammation and apoptosis via ROS-regulated PI3K/AKT signaling pathway

Quercetin is a dietary flavonoid compound extracted from various plants, such as apple and onions. Previous studies have revealed its anti-inflammatory, anti-cancer, antioxidant and anti-apoptotic activities. This study investigated the ability of quercetin to inhibit high fructose feeding- or LPS-induced atherosclerosis through regulating oxidative stress, apoptosis and inflammation response in vivo and in vitro experiments. 50 and 100mg/kg quercetin were used in our study, showing significant inhibitory role in high fructose-induced atherosclerosis via reducing reactive oxygen species (ROS) levels, Caspase-3 activation, inflammatory cytokines releasing, the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive cells and collagen contents as well as modulating apoptosis- and inflammation-related proteins expression. We also explored the protective effects of quercetin on atherosclerosis by phosphatidylinositide 3-kinases (PI3K)/Protein kinase B (AKT)-associated Bcl-2/Caspase-3 and nuclear factor kappa B (NF-κB) signal pathways activation, promoting AKT and Bcl-2 expression and reducing Caspase-3 and NF-κB activation. Quercetin reduced the atherosclerotic plaque size in vivo in high fructose feeding-induced mice assessed by oil red O. Also, in vitro experiments, quercetin displayed inhibitory role in LPS-induced ROS production, inflammatory response and apoptosis, which were linked with PI3K/AKT-regulated Caspase-3 and NF-κB activation. In conclusion, our results showed that quercetin inhibited atherosclerotic plaque development in high fructose feeding mice via PI3K/AKT activation regulated by ROS.

A human carboxypeptidase E/NF-α1 gene mutation in an Alzheimer's disease patient leads to dementia and depression in mice

Patients with Alzheimer's disease (AD), a common dementia among the aging population, often also suffer from depression. This comorbidity is poorly understood. Although most forms of AD are not genetically inherited, we have identified a new human mutation in the carboxypeptidase E (CPE)/neurotrophic factor-α1 (NF-α1) gene from an AD patient that caused memory deficit and depressive-like behavior in transgenic mice. This mutation consists of three adenosine inserts, introducing nine amino acids, including two glutamines into the mutant protein, herein called CPE-QQ. Expression of CPE-QQ in Neuro2a cells demonstrated that it was not secreted, but accumulated in the endoplasmic reticulum and was subsequently degraded by proteasomes. Expression of CPE-QQ in rat hippocampal neurons resulted in cell death, through increased ER stress and decreased expression of pro-survival protein, BCL-2. Transgenic mice expressing CPE-QQ did not show any difference in the processing enzyme activity of CPE compared with wild-type mice. However, the transgenic mice exhibited poor memory, depressive-like behavior, severely decreased dendrites in the hippocampal CA3 region and medial prefrontal cortex indicative of neurodegeneration, hyperphosphorylation of tau at Ser³⁹⁶, and diminished neurogenesis in the dentate gyrus at 50 weeks old. All these pathologies are associated with AD and the latter with depression and were observed in 50-week-old mice. Interestingly, the younger CPE-QQ mice (11 weeks old) did not show deficits in dendrite outgrowth and neurogenesis. This study has uncovered a human CPE/NF-α1 gene mutation that could lead to comorbidity of dementia and depression, emphasizing the importance of this gene in cognitive function.

Neurotrophic Factor-α1: A Key Wnt-β-Catenin Dependent Anti-Proliferation Factor and ERK-Sox9 Activated Inducer of Embryonic Neural Stem Cell Differentiation to Astrocytes in Neurodevelopment

Embryonic neurodevelopment involves inhibition of proliferation of multipotent neural stem cells (NSCs) followed by differentiation into neurons, astrocytes and oligodendrocytes to form the brain. We have identified a new neurotrophic factor, NF-α1, which inhibits proliferation and promotes differentiation of NSC/progenitors derived from E13.5 mouse cortex. Inhibition of proliferation of these cells was mediated through negatively regulating the Wnt pathway and decreasing β-catenin. NF-α1 induced differentiation of NSCs to astrocytes by enhancing Glial Fibrillary Acidic Protein (GFAP) expression through activating the ERK1/2-Sox9 signaling pathway. Cultured E13.5 cortical stem cells from NF-α1-knockout mice showed decreased astrocyte numbers compared to wild-type mice, which was rescued by treatment with NF-α1. In vivo, immunocytochemistry of brain sections and Western blot analysis of neocortex of mice showed a gradual increase of NF-α1 expression from E14.5 to P1 and a surge of GFAP expression at P1, the time of increase in astrogenesis. Importantly, NF-α1-Knockout mice showed ∼49% fewer GFAP positive astrocytes in the neocortex compared to WT mice at P1. Thus, NF-α1 is critical for regulating antiproliferation and cell fate determination, through differentiating embryonic stem cells to GFAP-positive astrocytes for normal neurodevelopment. Stem Cells 2017;35:557-571.

Neuroprotective effects of LMW and HMW FGF2 against amyloid beta toxicity in primary cultured hippocampal neurons

Basic Fibroblast growth factor (FGF2) is important in development and maintenance of central nervous system function. Studies have demonstrated that low molecular weight (LMW) FGF2 is a neuroprotective factor against various insults in vivo and in vitro. In the present study we investigated the neuroprotective effects of high molecular weight (HMW) and LMW FGF2 against amyloid beta-induced neurotoxicity. The results showed that both LMW and HMW FGF2 attenuated the amyloid beta toxicity in the primary cultured hippocampal neurons as measured by WST and LDH release assay. Moreover, the analysis suggested that HMW FGF2 had stronger neuroprotective effect than LMW FGF2. We then demonstrated that LMW and HMW FGF2 activated the ERK and AKT signaling pathways in a similar way. Furthermore, using the ERK inhibitor and AKT inhibitor, we found that the AKT signaling but not ERK signaling pathway was required for the neuroprotective effects of FGF2. Taken together, these results showed the neuroprotective effects of different forms of FGF2 in an AD model and the mechanism underlying the neuroprotection.

Carboxypeptidase E is a prediction marker for tumor recurrence in early-stage hepatocellular carcinoma

Tumor recurrence and metastasis are the major causes of death for hepatocellular carcinoma (HCC) patients who are able to receive curative resection. Identifying the predicting biomarkers for tumor recurrence would improve their survival. RNA extracted from fresh frozen tumors and adjacent non-tumor liver tissues of 120 HCC patients were obtained from Taiwan Liver Cancer Network (TLCN) in year 2010 for determination of the carboxypeptidase E (CPE) expression level (including its splicing mutant CPE-ΔN) in the tumor tissue (T) and paired non-tumor liver tissue (N) by real-time quantitative polymerase chain reaction. All patients were male, had chronic hepatitis B virus infection, were in the early pathology stage, and received curative resection. The T/N ratio of the CPE expression level was correlated with the updated survival data from TLCN in 2015. The CPE expression level in the 120 HCC patients was divided into three groups according to the T/N ratio: <1, ≥1 and ≤2, and >2, respectively. By multivariate analyses, the recurrence-free survival (RFS) was only significantly associated with the pathology stage and the CPE expression level. For overall survival (OS), only the CPE expression level was the significant prognostic factor. The CPE expression level was also significantly correlated with the tumor recurrence for both stage I (p = 0.0106) and stage II patients (p = 0.0006). The CPE mRNA expression level in HCC can be a useful biomarker for predicting tumor recurrence in HCC patients who are in the early pathology stage and able to receive curative resection.

Green Tea Polyphenols Attenuated Glutamate Excitotoxicity via Antioxidative and Antiapoptotic Pathway in the Primary Cultured Cortical Neurons

Green tea polyphenols are a natural product which has antioxidative and antiapoptotic effects. It has been shown that glutamate excitotoxicity induced oxidative stress is linked to neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. In this study we explored the neuroprotective effect of green teen polyphenols against glutamate excitotoxicity in the primary cultured cortical neurons. We found that green tea polyphenols protected against glutamate induced neurotoxicity in the cortical neurons as measured by MTT and TUNEL assays. Green tea polyphenols were then showed to inhibit the glutamate induced ROS release and SOD activity reduction in the neurons. Furthermore, our results demonstrated that green tea polyphenols restored the dysfunction of mitochondrial pro- or antiapoptotic proteins Bax, Bcl-2, and caspase-3 caused by glutamate. Interestingly, the neuroprotective effect of green tea polyphenols was abrogated when the neurons were incubated with siBcl-2. Taken together, these results demonstrated that green tea polyphenols protected against glutamate excitotoxicity through antioxidative and antiapoptotic pathways.

Effects of exogenous neurotrophin-3 on myocyte apoptosis and Ca(2+)-ATP enzyme levels following nerve injury in rats

This study aims to determine the influence of neurotrophin-3 (NT-3) plasmids on neuronal apoptosis and Ca(2+)-ATP enzyme levels in injured muscles. We also investigated the mechanism underlying the role of NT-3 in delaying muscle atrophy following a peripheral nerve injury. Sixty adult Wistar rats were used to generate the peripheral nerve injury models. The rats were randomly assigned to the saline and NT-3 groups. Related indicators, such as caspase-3 protein expression, skeletal muscle cell apoptosis, and Ca(2+)-ATP enzyme expression were quantified. The expression levels of caspase-3 and the histone-muscle cell apoptosis rate in the NT-3 group decreased at different post-operative times following peripheral nerve injury, whereas NT-3 expression and the sarcoplasmic reticulum Ca(2+)-ATP enzyme levels increased. Statistically significant differences were observed in the NT-3 group as compared to the saline group (P < 0.05). NT-3 mitigated muscle atrophy following peripheral nerve damage by inhibiting caspase-3 gene expression and increasing Ca(2+)-ATP enzymatic activity, ultimately reducing muscle apoptosis.

Gardenamide A Protects RGC-5 Cells from H₂O₂-Induced Oxidative Stress Insults by Activating PI3K/Akt/eNOS Signaling Pathway

Gardenamide A (GA) protects the rat retinal ganglion (RGC-5) cells against cell apoptosis induced by H₂O₂. The protective effect of GA was completely abrogated by the specific phosphoinositide 3-kinase (PI3K) inhibitor LY294002, and the specific protein kinase B (Akt) inhibitor Akt VIII respectively, indicating that the protective mechanism of GA is mediated by the PI3K/Akt signaling pathway. The specific extracellular signal-regulated kinase (ERK1/2) inhibitor PD98059 could not block the neuroprotection of GA. GA attenuated the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) induced by H₂O₂. Western blotting showed that GA promoted the phosphorylation of ERK1/2, Akt and endothelial nitric oxide synthase (eNOS), respectively, and effectively reversed the H₂O₂-inhibited phosphorylation of these three proteins. LY294002 completely inhibited the GA-activated phosphorylation of Akt, while only partially inhibiting eNOS. This evidence implies that eNOS may be activated directly by GA. PD98059 attenuated only partially the GA-induced phosphorylation of ERK1/2 with/without the presence of H₂O₂, indicating that GA may activate ERK1/2 directly. All these results put together confirm that GA protects RGC-5 cells from H₂O₂ insults via the activation of PI3K/Akt/eNOS signaling pathway. Whether the ERK1/2 signaling pathway is involved requires further investigations.

Rosiglitazone-activated PPARγ induces neurotrophic factor-α1 transcription contributing to neuroprotection

Brain peroxisome proliferator-activated receptor gamma (PPARγ), a member of the nuclear receptor superfamily of ligand-dependent transcription factors, is involved in neuroprotection. It is activated by the drug rosiglitazone, which then can increase the pro-survival protein B-cell lymphoma 2 (BCL-2), to mediate neuroprotection. However, the mechanism underlying this molecular cascade remains unknown. Here, we show that the neuroprotective protein neurotrophic factor-α1 (NF-α1), which also induces the expression of BCL-2, has a promoter that contains PPARγ-binding sites that are activated by rosiglitazone. Treatment of Neuro2a cells and primary hippocampal neurons with rosiglitazone increased endogenous NF-α1 expression and prevented H2 O2 -induced cytotoxicity. Concomitant with the increase in NF-α1, BCL-2 was also increased in these cells. When siRNA against NF-α1 was used, the induction of BCL-2 by rosiglitazone was prevented, and the neuroprotective effect of rosiglitazone was reduced. These results demonstrate that rosiglitazone-activated PPARγ directly induces the transcription of NF-α1, contributing to neuroprotection in neurons. We proposed the following cascade for neuroprotection against oxidative stress by rosiglitazone: Rosiglitazone enters the neuron and binds to peroxisome proliferator-activated receptor gamma (PPARγ) in the nucleus. The PPARγ-rosiglitazone complex binds to the neurotrophic factor-α1 (NF-α1) promoter and activates the transcription of NF-α1 mRNA which is then translated to the protein. NF-α1 is the secreted, binds to a cognate receptor and activates the extracellular signal-regulated kinases (ERK) pathway. This in turn enhances the expression of the pro-survival protein, B-cell lymphoma 2 (BCL-2) and inhibition of caspase 3 (Csp-3) to mediate neuroprotection under oxidative stress. Akt, protein kinase B (PKB).

Neurotrophic factor-α1 prevents stress-induced depression through enhancement of neurogenesis and is activated by rosiglitazone

Major depressive disorder is often linked to stress. Although short-term stress is without effect in mice, prolonged stress leads to depressive-like behavior, indicating that an allostatic mechanism exists in this difference. Here we demonstrate that mice after short-term (1 h per day for 7 days) chronic restraint stress (CRS), do not display depressive-like behavior. Analysis of the hippocampus of these mice showed increased levels of neurotrophic factor-α1 (NF-α1; also known as carboxypeptidase E, CPE), concomitant with enhanced fibroblast growth factor 2 (FGF2) expression, and an increase in neurogenesis in the dentate gyrus. In contrast, after prolonged (6 h per day for 21 days) CRS, mice show decreased hippocampal NF-α1 and FGF2 levels and depressive-like responses. In NF-α1-knockout mice, hippocampal FGF2 levels and neurogenesis are reduced. These mice exhibit depressive-like behavior that is reversed by FGF2 administration. Indeed, studies in cultured hippocampal neurons reveal that NF-α1 treatment directly upregulates FGF2 expression through extracellular signal-regulated kinase-Sp1 signaling. Thus, during short-term CRS, hippocampal NF-α1 expression is upregulated and has a key role in preventing the onset of depressive-like behavior through enhanced FGF2-mediated neurogenesis. To evaluate the therapeutic potential of this pathway, we examined, rosiglitazone (Rosi), a PPARγ agonist, which has been shown to have antidepressant activity in rodents and humans. Rosi upregulates FGF2 expression in a NF-α1-dependent manner in hippocampal neurons. Mice fed Rosi show increased hippocampal NF-α1 levels and neurogenesis compared with controls, thereby indicating the antidepressant action of this drug. Development of drugs that activate the NF-α1/FGF2/neurogenesis pathway can offer a new approach to depression therapy.

carboxypeptidase E-ΔN, a neuroprotein transiently expressed during development protects embryonic neurons against glutamate neurotoxicity

Neuroprotective proteins expressed in the fetus play a critical role during early embryonic neurodevelopment, especially during maternal exposure to alcohol and drugs that cause stress, glutamate neuroexcitotoxicity, and damage to the fetal brain, if prolonged. We have identified a novel protein, carboxypeptidase E-ΔN (CPE-ΔN), which is a splice variant of CPE that has neuroprotective effects on embryonic neurons. CPE-ΔN is transiently expressed in mouse embryos from embryonic day 5.5 to postnatal day 1. It is expressed in embryonic neurons, but not in 3 week or older mouse brains, suggesting a function primarily in utero. CPE-ΔN expression was up-regulated in embryonic hippocampal neurons in response to dexamethasone treatment. CPE-ΔN transduced into rat embryonic cortical and hippocampal neurons protected them from glutamate- and H₂O₂-induced cell death. When transduced into embryonic cortical neurons, CPE-ΔN was found in the nucleus and enhanced the transcription of FGF2 mRNA. Embryonic cortical neurons challenged with glutamate resulted in attenuated FGF2 levels and cell death, but CPE-ΔN transduced neurons treated in the same manner showed increased FGF2 expression and normal viability. This neuroprotective effect of CPE-ΔN was mediated by secreted FGF2. Through receptor signaling, FGF2 activated the AKT and ERK signaling pathways, which in turn increased BCL-2 expression. This led to inhibition of caspase-3 activity and cell survival.

Potential protection of 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside against staurosporine-induced toxicity on cultured rat hippocampus neurons

The present study explored the effect of 2,3,5,4'-tetrahydroxystilbene-2-O-β-d-glucoside (THSG) on the staurosporine (STS)-induced toxicity in cultured rat hippocampal neurons. The results showed that administration of 200μM of THSG significantly protected against 0.3μM of STS-induced apoptosis in cultured rat hippocampal neurons tested by methyl thiazolyl tetrazolium (MTT) and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assays. Furthermore, when the Akt signaling pathway was blocked by LY294002, an inhibitor of Phosphatidyl Inositol 3-kinase (PI3K), the protective effects of THSG against STS-induced neurotoxicity were abrogated. We further examined the involvement of PI3K/Akt signaling pathway in THSG protection against STS-induced cytotoxicity on cultured neurons and found that administration of THSG significantly inhibited the STS-induced decreases in the content of phosphorylated AKt (p-Akt). Moreover, we found that THSG rescued the down-regulation of B cell lymphoma/lewkmia-2 (Bcl2) and pro-caspase-3 (pro-Csp3) caused by STS in the neurons. These results indicate that THSG protect the cultured rat hippocampal neurons against STS-induced cytotoxicity and the PI3K/Akt signaling and mitochondrial apoptotic pathways are involved in the THSG-induced protective effects.

Carboxypeptidase E (NF-α1): a new trophic factor in neuroprotection

Carboxypeptidase E (CPE) is a prohormone-processing enzyme and sorting receptor that functions intracellularly. However, recent studies have demonstrated that CPE acts as a trophic factor extracellularly to up-regulate the expression of a pro-survival gene. This mini-review summarizes the roles of CPE in neuroprotection and the implications for neurodegenerative diseases.

Potential Protection of Coeloglossum viride var. Bracteatum Extract against Oxidative Stress in Rat Cortical Neurons

The present study explored the neuroprotective effect of Coeloglossum viride var. bracteatum extract (CE) against oxidative stress in rat cortical neurons. The results demonstrated that administration of CE inhibited hydrogen peroxide-induced neurotoxicity tested by MTT, LDH release, and TUNEL assays. We further found that CE inhibited the activation of caspase-3 (Csp3) induced by hydrogen peroxide. Moreover, CE was found to reverse the hydrogen peroxide-induced downregulation of active AKT and Bcl-2. We then showed that the neuroprotective effect of CE was blocked by adding the AKT inhibitor, Ly294002. Thus, our data strongly indicated that CE played a neuroprotective role against oxidative stress-induced neurotoxicity.

Carboxypeptidase E protects hippocampal neurons during stress in male mice by up-regulating prosurvival BCL2 protein expression

Prolonged chronic stress causing elevated plasma glucocorticoids leads to neurodegeneration. Adaptation to stress (allostasis) through neuroprotective mechanisms can delay this process. Studies on hippocampal neurons have identified carboxypeptidase E (CPE) as a novel neuroprotective protein that acts extracellularly, independent of its enzymatic activity, although the mechanism of action is unclear. Here, we aim to determine if CPE plays a neuroprotective role in allostasis in mouse hippocampus during chronic restraint stress (CRS), and the molecular mechanisms involved. Quantitative RT-PCR/in situ hybridization and Western blots were used to assay for mRNA and protein. After mild CRS (1 h/d for 7 d), CPE protein and mRNA were significantly elevated in the hippocampal CA3 region, compared to naïve littermates. In addition, luciferase reporter assays identified a functional glucocorticoid regulatory element within the cpe promoter that mediated the up-regulation of CPE expression in primary hippocampal neurons following dexamethasone treatment, suggesting that circulating plasma glucocorticoids could evoke a similar effect on CPE in the hippocampus in vivo. Overexpression of CPE in hippocampal neurons, or CRS in mice, resulted in elevated prosurvival BCL2 protein/mRNA and p-AKT levels in the hippocampus; however, CPE(-/-) mice showed a decrease. Thus, during mild CRS, CPE expression is up-regulated, possibly contributed by glucocorticoids, to mediate neuroprotection of the hippocampus by enhancing BCL2 expression through AKT signaling, and thereby maintaining allostasis.

Carboxypeptidase E promotes cancer cell survival, but inhibits migration and invasion

Carboxypeptidase E (CPE), a prohormone processing enzyme is highly expressed and secreted from (neuro)endocrine tumors and gliomas, and has been implicated in cancer progression by promoting tumor growth. Our study demonstrates that secreted or exogenously applied CPE promotes survival of pheochromocytoma (PC12) and hepatocellular carcinoma (MHCC97H) cells under nutrient starvation and hypoxic conditions, but had no effect on their proliferation. CPE also reduced migration and invasion of fibrosarcoma (HT1080) cells. We show that CPE treatment mediates survival of MHCC97H cells during metabolic stress by up-regulating the expression of anti-apoptotic protein BCL-2, and other pro-survival genes, via activation of the ERK1/2 pathway.