A network map of BDNF/TRKB and BDNF/p75NTR signaling system

p75 neurotrophin receptor modulation in mild to moderate Alzheimer disease: a randomized, placebo-controlled phase 2a trial

p75 neurotrophin receptor (p75NTR) signaling pathways substantially overlap with degenerative networks active in Alzheimer disease (AD). Modulation of p75NTR with the first-in-class small molecule LM11A-31 mitigates amyloid-induced and pathological tau-induced synaptic loss in preclinical models. Here we conducted a 26-week randomized, placebo-controlled, double-blinded phase 2a safety and exploratory endpoint trial of LM11A-31 in 242 participants with mild to moderate AD with three arms: placebo, 200 mg LM11A-31 and 400 mg LM11A-31, administered twice daily by oral capsules. This trial met its primary endpoint of safety and tolerability. Within the prespecified secondary and exploratory outcome domains (structural magnetic resonance imaging, fluorodeoxyglucose positron-emission tomography and cerebrospinal fluid biomarkers), significant drug-placebo differences were found, consistent with the hypothesis that LM11A-31 slows progression of pathophysiological features of AD; no significant effect of active treatment was observed on cognitive tests. Together, these results suggest that targeting p75NTR with LM11A-31 warrants further investigation in larger-scale clinical trials of longer duration. EU Clinical Trials registration: 2015-005263-16 ; ClinicalTrials.gov registration: NCT03069014 .

PI3K/AKT pathway as a pivotal regulator of epithelial-mesenchymal transition in lung tumor cells

Lung cancer, as the leading cause of cancer related deaths, is one of the main global health challenges. Despite various progresses in diagnostic and therapeutic methods, there is still a high rate of mortality among lung cancer patients, which can be related to the lack of clinical symptoms to differentiate lung cancer from the other chronic respiratory disorders in the early tumor stages. Most lung cancer patients are identified in advanced and metastatic tumor stages, which is associated with a poor prognosis. Therefore, it is necessary to investigate the molecular mechanisms involved in lung tumor progression and metastasis in order to introduce early diagnostic markers as well as therapeutic targets. Epithelial-mesenchymal transition (EMT) is considered as one of the main cellular mechanisms involved in lung tumor metastasis, during which tumor cells gain the metastatic ability by acquiring mesenchymal characteristics. Since, majority of the oncogenic signaling pathways exert their role in tumor cell invasion by inducing the EMT process, in the present review we discussed the role of PI3K/AKT signaling pathway in regulation of EMT process during lung tumor metastasis. It has been reported that the PI3K/AKT acts as an inducer of EMT process through the activation of EMT-specific transcription factors in lung tumor cells. MicroRNAs also exerted their inhibitory effects during EMT process by inhibition of PI3K/AKT pathway. This review can be an effective step towards introducing the PI3K/AKT pathway as a suitable therapeutic target to inhibit the EMT process and tumor metastasis in lung cancer patients.

The role of sphingosine-1-phosphate in the development and progression of Parkinson's disease

Parkinson's disease (PD) could be viewed as a proteinopathy caused by changes in lipids, whereby modifications in lipid metabolism may lead to protein alterations, such as the accumulation of alpha-synuclein (α-syn), ultimately resulting in neurodegeneration. Although the loss of dopaminergic neurons in the substantia nigra is the major clinical manifestation of PD, the etiology of it is largely unknown. Increasing evidence has highlighted the important role of lipids in the pathophysiology of PD. Sphingosine-1-phosphate (S1P), a signaling lipid, has been suggested to have a potential association with the advancement and worsening of PD. Therefore, better understanding the mechanisms and regulatory proteins is of high interest. Most interestingly, S1P appears to be an important target to offers a new strategy for the diagnosis and treatment of PD. In this review, we first introduce the basic situation of S1P structure, function and regulation, with a special focus on the several pathways. We then briefly describe the regulation of S1P signaling pathway on cells and make a special focused on the cell growth, proliferation and apoptosis, etc. Finally, we discuss the function of S1P as potential therapeutic target to improve the clinical symptoms of PD, and even prevent the progression of the PD. In the context of PD, the functions of S1P modulators have been extensively elucidated. In conclusion, S1P modulators represent a novel and promising therapeutic principle and therapeutic method for PD. However, more research is required before these drugs can be considered as a standard treatment option for PD.

A network map of GDNF/RET signaling pathway in physiological and pathological conditions

Glial cell line-derived neurotrophic factor (GDNF) signals through a multi-component receptor system predominantly consisting of glycosyl-phosphatidylinositol-anchored GDNF family receptor alpha-1 (GFRα1) and the Rearranged during transfection (RET) receptor tyrosine kinase. GDNF/RET signaling is vital to the central and peripheral nervous system, kidney morphogenesis, and spermatogenesis. In addition, the dysregulation of the GDNF/RET signaling has been implicated in the pathogenesis of cancers. Despite the extensive research on GDNF/RET signaling, a molecular network of reactions induced by GDNF reported across the published literature. However, a comprehensive GDNF/RET pathway resource is currently unavailable. We describe an integrated signaling pathway reaction map of GDNF/RET consisting of 1151 molecular reactions. These include information pertaining to 52 molecular association events, 70 enzyme catalysis events, 36 activation/inhibition events, 22 translocation events, 856 gene regulation events, and 115 protein-level expression events induced by GDNF in diverse cell types. We developed a comprehensive GDNF/RET signaling network map based on these molecular reactions. The pathway map was made accessible through WikiPathways database ( https://www.wikipathways.org/index.php/Pathway:WP5143 ). Biocuration and development of gene regulatory network map of GDNF/RET signaling pathway.

Effect of β-hydroxybutyrate on behavioral alterations, molecular and morphological changes in CNS of multiple sclerosis mouse model

Multiple sclerosis (MS) is a chronic inflammatory and degenerative disease of central nervous system (CNS). Aging is the most significant risk factor for the progression of MS. Dietary modulation (such as ketogenic diet) and caloric restriction, can increase ketone bodies, especially β-hydroxybutyrate (BHB). Increased BHB has been reported to prevent or improve age-related disease. The present studies were performed to understand the therapeutic effect and potential mechanisms of exogenous BHB in cuprizone (CPZ)-induced demyelinating model. In this study, a continuous 35 days CPZ mouse model with or without BHB was established. The changes of behavior function, pathological hallmarks of CPZ, and intracellular signal pathways in mice were detected by Open feld test, Morris water maze, RT-PCR, immuno-histochemistry, and western blot. The results showed that BHB treatment improved behavioral performance, prevented myelin loss, decreased the activation of astrocyte as well as microglia, and up-regulated the neurotrophin brain-derived neurotrophic factor in both the corpus callosum and hippocampus. Meanwhile, BHB treatment increased the number of MCT1+ cells and APC+ oligodendrocytes. Furthermore, the treatment decreased the expression of HDAC3, PARP1, AIF and TRPA1 which is related to oligodendrocyte (OL) apoptosis in the corpus callosum, accompanied by increased expression of TrkB. This leads to an increased density of doublecortin (DCX)+ neuronal precursor cells and mature NeuN+ neuronal cells in the hippocampus. As a result, BHB treatment effectively promotes the generation of PDGF-Ra+ (oligodendrocyte precursor cells, OPCs), Sox2+ cells and GFAP+ (astrocytes), and decreased the production of GFAP+ TRAP1+ cells, and Oligo2+ TRAP1+ cells in the corpus callosum of mouse brain. Thus, our results demonstrate that BHB treatment efficiently supports OPC differentiation and decreases the OLs apoptosis in CPZ-intoxicated mice, partly by down-regulating the expression of TRPA1 and PARP, which is associated with the inhibition of the p38-MAPK/JNK/JUN pathway and the activation of ERK1/2, PI3K/AKT/mTOR signaling, supporting BHB treatment adjunctive nutritional therapy for the treatment of chronic demyelinating diseases, such as multiple sclerosis (MS).

The combination of chronic stress and smoke exacerbated depression-like changes and lung cancer factor expression in A/J mice: Involve inflammation and BDNF dysfunction

OBJECTIVE

Depression is positively correlated with the high incidence and low survival rate of cancers, while more cancer patients suffer depression. However, the interaction between depression and cancer, and possible underline mechanisms are unclear.

METHODS

Chronic unpredictable mild stress (CUMS) was used to induce depression, and smoke to induce lung cancer in lung cancer vulnerable AJ mice. After 8 weeks, sucrose preference and forced swimming behaviors were tested. Blood corticosterone concentration, and levels of cytokines, lung cancer-related factors, brain-derived neurotrophic factor (BDNF) and apoptosis-related factors in the lung, amygdala and hippocampus were measured.

RESULTS

Compared to control group, CUMS or smoke decreased sucrose consumption and increased immobility time, which were deteriorated by stress+smoke. CUMS, smoke or both combination decreased mononuclear viability and lung TNF-α concentration, increased serum corticosterone and lung interleukin (IL)-1, IL-2, IL-6, IL-8, IL-10, IL-12 and HSP-90α concentrations. Furthermore, stress+smoke caused more increase in corticosterone and IL-10, but decreased TNF-α. In parallel, in the lung, Bcl-2/Bax and lung cancer-related factors CDK1, CDC20, P38α etc were significantly increased in stress+smoke group. Moreover, CUMS decreased BDNF, while CUMS or smoke increased TrkB and P75 concentrations, which were exacerbated by stress+smoke. In the amygdala, except for CUMS largely increased Bax/Bcl-2 and decreased TrkB, each single factor decreased BDNF and IL-10, but increased P75, IL-1β, IL-12, TNF-α concentrations. Changes in Bax/Bcl-2, IL-10 and TNF-α were further aggravated by the combination. In the hippocampus, except for CUMS largely increased P75 concentration, each single factor significantly increased Bax/Bcl-2 ratio, IL-1β and TNF-α, but decreased BDNF, TrkB and IL-10 concentrations. Changes in Bax, Bax/Bcl-2, IL-10 and TNF-α were further aggravated by the combination.

CONCLUSION

These results suggest that a synergy between CUMS and smoke exposure could promote the development of depression and lung cancer, through CUMS increased the risk of cancer occurrence, and conversely lung cancer inducer smoke exposure deteriorated depressive symptoms.

Recent Advances on the Role of Brain-Derived Neurotrophic Factor (BDNF) in Neurodegenerative Diseases

Neurotrophins, such as brain-derived neurotrophic factor (BDNF), are essential for neuronal survival and growth. The signaling cascades initiated by BDNF and its receptor are the key regulators of synaptic plasticity, which plays important role in learning and memory formation. Changes in BDNF levels and signaling pathways have been identified in several neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease, and have been linked with the symptoms and course of these diseases. This review summarizes the current understanding of the role of BDNF in several neurodegenerative diseases, as well as the underlying molecular mechanism. The therapeutic potential of BDNF treatment is also discussed, in the hope of discovering new avenues for the treatment of neurodegenerative diseases.

MicroRNAs as the critical regulators of cell migration and invasion in thyroid cancer

Thyroid cancer (TC) is one of the most frequent endocrine malignancies that is more common among females. Tumor recurrence is one of the most important clinical manifestations in differentiated TC which is associated with different factors including age, tumor size, and histological features. Various molecular processes such as genetic or epigenetic modifications and non-coding RNAs are also involved in TC progression and metastasis. The epithelial-to-mesenchymal transition (EMT) is an important biological process during tumor invasion and migration that affects the initiation and transformation of early-stage tumors into invasive malignancies. A combination of transcription factors, growth factors, signaling pathways, and epigenetic regulations affect the thyroid cell migration and EMT process. MicroRNAs (miRNAs) are important molecular factors involved in tumor metastasis by regulation of EMT-activating signaling pathways. Various miRNAs are involved in the signaling pathways associated with TC metastasis which can be used as diagnostic and therapeutic biomarkers. Since, the miRNAs are sensitive, specific, and non-invasive, they can be suggested as efficient and optimal biomarkers of tumor invasion and metastasis. In the present review, we have summarized all of the miRNAs which have been significantly involved in thyroid tumor cells migration and invasion. We also categorized all of the reported miRNAs based on their cellular processes to clarify the molecular role of miRNAs during thyroid tumor cell migration and invasion. This review paves the way of introducing a non-invasive diagnostic and prognostic panel of miRNAs in aggressive and metastatic TC patients.

Brain-Derived Neurotrophic Factor: A Connecting Link Between Nutrition, Lifestyle, and Alzheimer’s Disease

Brain-derived neurotrophic factor (BDNF) involving tropomyosin kinase B and low affinity p75 neurotropin receptors is the most abundant and researched neurotropins in mammal’s brain. It is one of the potential targets for therapeutics in Alzheimer’s disease (AD) owing to its key role in synaptic plasticity. Low levels of BDNF are implicated in the pathophysiology of neurological diseases including AD. However, a healthy lifestyle, exercise, and dietary modifications are shown to positively influence insulin regulation in the brain, reduce inflammation, and up-regulate the levels of BDNF, and are thus expected to have roles in AD. In this review, the relationship between BDNF, mental health, and AD is discussed. Insights into the interrelationships between nutrition, lifestyle, and environment with BDNF and possible roles in AD are also provided in the review. The review sheds light on the possible new therapeutic targets in neurodegenerative diseases.

Re-Expression of Poly/Oligo-Sialylated Adhesion Molecules on the Surface of Tumor Cells Disrupts Their Interaction with Immune-Effector Cells and Contributes to Pathophysiological Immune Escape

Glycans linked to surface proteins are the most complex biological macromolecules that play an active role in various cellular mechanisms. This diversity is the basis of cell-cell interaction and communication, cell growth, cell migration, as well as co-stimulatory or inhibitory signaling. Our review describes the importance of neuraminic acid and its derivatives as recognition elements, which are located at the outermost positions of carbohydrate chains linked to specific glycoproteins or glycolipids. Tumor cells, especially from solid tumors, mask themselves by re-expression of hypersialylated neural cell adhesion molecule (NCAM), neuropilin-2 (NRP-2), or synaptic cell adhesion molecule 1 (SynCAM 1) in order to protect themselves against the cytotoxic attack of the also highly sialylated immune effector cells. More particularly, we focus on α-2,8-linked polysialic acid chains, which characterize carrier glycoproteins such as NCAM, NRP-2, or SynCam-1. This characteristic property correlates with an aggressive clinical phenotype and endows them with multiple roles in biological processes that underlie all steps of cancer progression, including regulation of cell-cell and/or cell-extracellular matrix interactions, as well as increased proliferation, migration, reduced apoptosis rate of tumor cells, angiogenesis, and metastasis. Specifically, re-expression of poly/oligo-sialylated adhesion molecules on the surface of tumor cells disrupts their interaction with immune-effector cells and contributes to pathophysiological immune escape. Further, sialylated glycoproteins induce immunoregulatory cytokines and growth factors through interactions with sialic acid-binding immunoglobulin-like lectins. We describe the processes, which modulate the interaction between sialylated carrier glycoproteins and their ligands, and illustrate that sialic acids could be targets of novel therapeutic strategies for treatment of cancer and immune diseases.

Evaluating Neurotrophin Signaling Using MicroRNA Perilymph Profiling in Cochlear Implant Patients With and Without Residual Hearing

HYPOTHESIS

MicroRNAs predicted to regulate neurotrophin signaling can be found in human perilymph.

BACKGROUND

Animal and human temporal bone studies suggest that spiral ganglion health can affect cochlear implant (CI) outcomes. Neurotrophins have been identified as a key factor in the maintenance of spiral ganglion health. Changes in miRNAs may regulate neurotrophin signaling and may reflect neurotrophin expression levels.

METHODS

Perilymph sampling was carried out in 18 patients undergoing cochlear implantation or stapedotomy. Expression of miRNAs in perilymph was evaluated using an Agilent miRNA gene chip. Using ingenuity pathway analysis (IPA) software, miRNAs targeting neurotrophin signaling pathway genes present in a cochlear cDNA library were annotated. Expression levels of miRNAs in perilymph were correlated to the patients' preoperative pure-tone average.

RESULTS

Expression of mRNAs coding for neurotrophins and their receptors were identified in tissue obtained from normal human cochlea during skull base surgery. We identified miRNAs predicted to regulate these signaling cascades, including miR-1207-5p, miR-4651, miR-103-3p, miR-100-5p, miR-221-3p, miR-200-3p. There was a correlation between poor preoperative hearing and lower expression of miR-1207 (predicted to regulate NTR3) and miR-4651 (predicted to regulate NTR2). Additionally, miR-3960, miR-4481, and miR-675 showed significant differences in expression level when comparing mild and profound hearing loss patients.

CONCLUSIONS

Expression of some miRNAs that are predicted to regulate neurotrophin signaling in the perilymph of cochlear implant patients vary with the patient's level of residual hearing. These miRNAs may serve as biomarkers for changes in neurotrophin signaling.

ID4 predicts poor prognosis and promotes BDNF-mediated oncogenesis of colorectal cancer

Inhibitors of DNA binding and cell differentiation (ID) proteins regulate cellular differentiation and tumor progression. Whether ID family proteins serve as a linkage between pathological differentiation and cancer stemness in colorectal cancer is largely unknown. Here, the expression of ID4, but not other ID family proteins, was enriched in LGR5-high colon cancer stem cells. Its high expression was associated with poor pathological differentiation of colorectal tumors and shorter survival in patients. Knockdown of ID4 inhibited the growth and dissemination of colon cancer cells, while enhancing chemosensitivity. Through gene expression profiling analysis, brain-derived neurotrophic factor (BDNF) was identified as a downstream target of ID4 expression in colorectal cancer. BDNF knockdown decreased the growth and migration of colon cancer cells, and its expression enhanced dissemination, anoikis resistance and chemoresistance. ID4 silencing attenuated the epithelial-to-mesenchymal transition pattern in colon cancer cells. Gene cluster analysis revealed that ID4 and BDNF expression was clustered with mesenchymal markers and distant from epithelial genes. BDNF silencing decreased the expression of mesenchymal markers Vimentin, CDH2 and SNAI1. These findings demonstrated that ID4-BDNF signaling regulates colorectal cancer survival, with the potential to serve as a prognostic marker in colorectal cancer.

Hesperidin Interacts With CREB-BDNF Signaling Pathway to Suppress Pentylenetetrazole-Induced Convulsions in Zebrafish

Hesperidin (3,5,7-trihydroxyflavanone 7-rhamnoglucoside) is a β-7-rutinoside of hesperetin (4'-methoxy-3',5,7-trihydroxyflavanone), abundantly found in citrus fruits and known to interact with various cellular pathways to show a variety of pharmacological effects. The present study was envisaged to understand the anticonvulsant effect of hesperidin in a zebrafish model of pentylenetetrazole (PTZ)-induced convulsions, with the support of in silico docking. Healthy zebrafish larvae were preincubated with hesperidin (1, 5, and 10 µM) for 1 h, before PTZ exposure. Hesperidin treatment significantly increased the seizure latency and minimized PTZ-induced hyperactive responses. A significant reduction in c-fos expression further supported the suppression of neuronal excitation following hesperidin incubation in the larvae exposed to PTZ. The treatment also modulated larval bdnf expression and reduced the expression of il-10. The results of in vivo studies were further supported by in silico docking analysis, which showed the affinity of hesperidin for the N-methyl-d-aspartate receptor, the gamma-aminobutyric acid receptor, Interleukin 10 and the TrkB receptor of brain-derived neurotrophic factor. The results concluded that hesperidin suppresses PTZ-mediated seizure in zebrafish larvae through interaction with the central CREB-BDNF pathway.

Neurogenesis and Neuroplasticity in Major Depression: Its Therapeutic Implication

The neurochemical model of depression, based on monoaminergic theories, does not allow on its own to understand the mechanism of action of antidepressants. This approach does not explain the gap between the immediate biochemical modulations induced by antidepressants and the time required for their clinical action. Several hypotheses have been developed to try to explain more precisely the action of these molecules, each of them involving mechanisms of receptor regulation. At the same time, data on the neuroanatomy of depression converge toward the existence of specific lesions of this pathology. This chapter aims to provide an overview of recent advances in understanding the mechanisms of neural plasticity involved in pathophysiology depression and in its treatment.

An assembly of galanin-galanin receptor signaling network

The galanin receptor family of proteins is present throughout the central nervous system and endocrine system. It comprises of three subtypes-GalR1, GalR2, and GalR3; all of which are G-protein-coupled receptors. Galanin predominantly acts as an inhibitory, hyper-polarizing neuromodulator, which has several physiological as well as pathological functions. Galanin has a role in mediating food intake, memory, sexual behavior, nociception and is also associated with diseases such as Alzheimer's disease, epilepsy, diabetes mellitus, and chronic pain. However, the understanding of signaling mechanisms of the galanin family of neuropeptides is limited and an organized pathway map is not yet available. Therefore, a detailed literature mining of the publicly available articles pertaining to the galanin receptor was followed by manual curation of the reactions and their integration into a map. This resulted in the cataloging of molecular reactions involving 64 molecules into five categories such as molecular association, activation/inhibition, catalysis, transport, and gene regulation. For enabling easy access of biomedical researchers, the galanin-galanin receptor signaling pathway data was uploaded to WikiPathways ( https://www.wikipathways.org/index.php/Pathway:WP4970 ), a freely available database of biological pathways.

Effects of exercise and pharmacological inhibition of histone deacetylases (HDACs) on epigenetic regulations and gene expressions crucial for neuronal plasticity in the motor cortex

The objective of this study was to examine the effect of epigenetic treatment using an histone deacetylases (HDAC) inhibitor in addition to aerobic exercise on the epigenetic markers and neurotrophic gene expressions in the motor cortex, to find a more enriched brain pre-conditioning for motor learning in neurorehabilitation. ICR mice were divided into four groups based on two factors: HDAC inhibition and exercise. Intraperitoneal administration of an HDAC inhibitor (1.2 g/kg sodium butyrate, NaB) and treadmill exercise (approximately at 10 m/min for 60 min) were conducted five days a week for four weeks. NaB administration inhibited total HDAC activity and enhanced acetylation level of histones specifically in histone H4, accompanying the increase of transcription levels of immediate-early genes (IEGs) (c-fos and Arc) and neurotrophins (BDNF and NT-4) crucial for neuroplasticity in the motor cortex. However, exercise enhanced HDAC activity and acetylation level of histone H4 and H3 without the modification of transcription levels. In addition, there were no synergic effects between HDAC inhibition and the exercise regime on the gene expressions. This study showed that HDAC inhibition could present more enriched condition for neuroplasticity to the motor cortex. However, exercise-induced neurotrophic gene expressions could depend on exercise regimen based on the intensity, the term etc. Therefore, this study has a novelty suggesting that pharmacological HDAC inhibition could be an alternative potent approach to present a neuronal platform with enriched neuroplasticity for motor learning and motor recovery, however, an appropriate exercise regimen is expected in this approach.

Rodent Models of Amyloid-Beta Feature of Alzheimer's Disease: Development and Potential Treatment Implications

Alzheimer's disease (AD) is the most common neurodegenerative disorder worldwide and causes severe financial and social burdens. Despite much research on the pathogenesis of AD, the neuropathological mechanisms remain obscure and current treatments have proven ineffective. In the past decades, transgenic rodent models have been used to try to unravel this disease, which is crucial for early diagnosis and the assessment of disease-modifying compounds. In this review, we focus on transgenic rodent models used to study amyloid-beta pathology in AD. We also discuss their possible use as promising tools for AD research. There is still no effective treatment for AD and the development of potent therapeutics are urgently needed. Many molecular pathways are susceptible to AD, ranging from neuroinflammation, immune response, and neuroplasticity to neurotrophic factors. Studying these pathways may shed light on AD pathophysiology as well as provide potential targets for the development of more effective treatments. This review discusses the advantages and limitations of these models and their potential therapeutic implications for AD.

Low-Level Inhibition of GABAergic Synapses Enhances Gene Expressions Crucial for Neuronal Plasticity in the Hippocampus After Ischemic Stroke

OBJECTIVE

Pharmacological inhibition of GABAergic synapses could represent a potent neuromodulation strategy to activate hippocampal neurons and increase neurotrophic factor gene expression, thus exerting a beneficial effect on post-stroke cognitive impairment (PSCI). The objective of this study was to assess the effects of low-level inhibition of GABAergic synapses on hippocampal gene expressions related to neuroplasticity using the middle cerebral artery occlusion surgery (MCAO) ischemic stroke rat model.

METHODS

The animals were randomly assigned to three experimental groups-(1) a sham operated group (SHAM), (2) a control group (CON), and (3) a bicuculline group (BIC). MCAO was performed in the CON and BIC groups. A non-epileptic dose of bicuculline (0.25 mg/kg) was intraperitoneally administered every day for two weeks, starting three days after surgery, to the rats in the BIC group. The mRNA expression of brain-derived neurotrophic factor (BDNF), tropomyosin-related kinase B (TrkB), in relation to neurotrophic intracellular signal, p75, in relation to apoptosis, and synaptophysin (SYP) and PSD-95, synaptic markers, were assessed in the hippocampus ipsilateral to the ischemic site.

RESULTS

MCAO increased the gene expression of TrkB. Furthermore, MCAO plus bicuculline administration increased the expression ratio of TrkB to p75 and SYP gene expression.

CONCLUSION

Therefore, this study showed that administration of bicuculline after stroke beneficially modulated the expression of crucial genes for neuroplasticity, including BDNF receptors and SYP, in the ipsilateral hippocampus, suggesting that low-level inhibition of GABAergic synapses could lead to beneficial neuromodulation in the hippocampus after stroke.

Brain-derived neurotrophic factor polymorphism Val66Met protects against cancer-related fatigue

Cancer-related fatigue is an extremely common and debilitating psychiatric symptom that affects up to 80% of cancer patients. Despite its negative impact on the patient's quality of life, there is no well-established biomarker or mechanisms associated with this debilitating condition. The functional brain-derived neurotrophic factor (BDNF) Val66Met single nucleotide polymorphism (SNP) has been associated with a variety of psychiatric illnesses. We hypothesized that Val66Met may influence the risk for developing cancer-related fatigue. BDNF Val66Met was analyzed by polymerase chain reaction in 180 patients with confirmed cancer diagnoses. Fatigue was measured using the Functional Assessment of Cancer Therapy-Fatigue (FACIT-Fatigue) questionnaire. Depression was measured using the Hamilton Depression Scale (HAM-D). Data were transformed when necessary and regression models were constructed to access the association between genotype and symptom severity. Participants carrying the Met allele reported significantly less fatigue compared to the Val/Val genotype group. The presence of the Met allele did not influence depression levels. The results suggest that the BDNF Val66Met polymorphism confers protective advantage against cancer-related fatigue; whereas having the Val/Val genotype may be a genetic risk factor. Findings from this study not only provide clues to the neural basis of cancer-related fatigue, but also allow for symptom severity prediction and patient education with the goal to improve symptom management.

New insights on brain-derived neurotrophic factor epigenetics: from depression to memory extinction

Advances in characterizing molecular profiles provide valuable insights and opportunities for deciphering the neuropathology of depression. Although abnormal brain-derived neurotrophic factor (BDNF) expression in depression has gained much support from preclinical and clinical research, how it mediates behavioral alterations in the depressed state remains largely obscure. Environmental factors contribute significantly to the onset of depression and produce robust epigenetic changes. Epigenetic regulation of BDNF, as one of the most characterized gene loci in epigenetics, has recently emerged as a target in research on memory and psychiatric disorders. Specifically, epigenetic alterations of BDNF exons are heavily involved in mediating memory functions and antidepressant effects. In this review, we discuss key research on stress-induced depression from both preclinical and clinical studies, which revealed that differential epigenetic regulation of specific BDNF exons is associated with depression pathophysiology. Considering that BDNF has a central role in depression, we argue that memory extinction, an adaptive response to fear exposure, is dependent on BDNF modulation and holds promise as a prospective target for alleviating or treating depression and anxiety disorders.

Feeding and food availability modulate brain-derived neurotrophic factor, an orexigen with metabolic roles in zebrafish

Emerging findings point to a role for brain-derived neurotrophic factor (BDNF) on feeding in mammals. However, its role on energy balance is unclear. Moreover, whether BDNF regulates energy homeostasis in non-mammals remain unknown. This research aimed to determine whether BDNF is a metabolic peptide in zebrafish. Our results demonstrate that BDNF mRNAs and protein, as well as mRNAs encoding its receptors trkb2, p75ntra and p75ntrb, are detectable in the zebrafish brain, foregut and liver. Intraperitoneal injection of BDNF increased food intake at 1, 2 and 6 h post-administration, and caused an upregulation of brain npy, agrp and orexin, foregut ghrelin, and hepatic leptin mRNAs, and a reduction in brain nucb2. Fasting for 7 days increased bdnf and p75ntrb mRNAs in the foregut, while decreased bdnf, trkb2, p75ntra and p75ntrb mRNAs in the brain and liver. Additionally, the expression of bdnf and its receptors increased preprandially, and decreased after a meal in the foregut and liver. Finally, we observed BDNF-induced changes in the expression and/or activity of enzymes involved in glucose and lipid metabolism in the liver. Overall, present results indicate that BDNF is a novel regulator of appetite and metabolism in fish, which is modulated by energy intake and food availability.

MicroRNA-147 targets BDNF to inhibit cell proliferation, migration and invasion in non-small cell lung cancer

Lung cancer is one of the most common cancers that threaten human life and health. Recently, microRNAs (miRNAs) have been shown to play a unique role in many malignancies. Although the dysregulation of miR-147 has been detected in non-small cell lung cancer (NSCLC), the biological function of miR-147 is still unknown in NSCLC. The expression of miR-147 was observed by real-time quantitative polymerase chain reaction (RT-qPCR). Methyl thiazolyl tetrazolium (MTT) and Transwell assays were used to investigate the function of miR-147 in NSCLC. Target genes of miR-147 were verified using dual luciferase reporter assay. Western blot analysis was used to explore the PI3K/AKT pathway. The expression of miR-147 was decreased in NSCLC tissues, which was associated with poor prognosis in NSCLC patients. Furthermore, overexpression of miR-147 inhibited the viability and metastasis of NSCLC cells. In addition, miR-147 inhibited epithelial-mesenchymal transition (EMT) and inactivated the PI3K/AKT pathway in NSCLC. Furthermore, miR-147 directly targets brain-derived neurotrophic factor (BDNF) and negatively regulates BDNF expression in NSCLC. Upregulation of BDNF attenuated the inhibitory effect of miR-147 in NSCLC. In conclusion, miR-147 inhibits cell proliferation, migration and invasion in NSCLC through suppressing BDNF expression.

MiR-489-3p inhibits cell proliferation, migration, and invasion, and induces apoptosis, by targeting the BDNF-mediated PI3K/AKT pathway in glioblastoma

Among astrocyte tumors, glioblastoma (GBM) is the most malignant glioma, highly aggressive and invasive, with extremely poor prognosis. Previous research has reported that microRNAs (miRNAs) participate in the progression of many cancers. Thus, this study aimed to explore the role and the underlying mechanisms of microRNA (miR)-489-3p in GBM progression. The expression of miR-489-3p and brain-derived neurotrophic factor (BDNF) mRNA was measured by quantitative real-time polymerase chain reaction. Western blot analysis was used to detect BDNF protein and the PI3K/AKT pathway-related protein. Cell proliferation, apoptosis, migration, and invasion were analyzed using CKK-8 assay, flow cytometry, and transwell assay, respectively. The interaction between BDNF and miR-489-3p was explored by luciferase reporter assay and RNA immunoprecipitation (RIP) assay. MiR-489-3p was down-regulated and BDNF was up-regulated in GBM tissues and cells. MiR-489-3p re-expression or BDNF knockdown inhibited GBM cell proliferation, migration, and invasion, and promoted apoptosis. BDNF was a target of miR-489-3p, and BDNF up-regulation reversed the effects of miR-489-3p on GBM cells. The protein levels of p-AKT and p-PI3K were notably reduced in GBM cells by overexpression of miR-489-3p, but were rescued following BDNF up-regulation. Therefore, miR-489-3p inhibited proliferation, migration, and invasion, and induced apoptosis, by targeting the BDNF-mediated PI3K/AKT pathway in GBM, providing new strategies for clinical treatment of GBM.

Amelioration of BPSD-Like Phenotype and Cognitive Decline in SAMP8 Mice Model Accompanied by Molecular Changes after Treatment with I2-Imidazoline Receptor Ligand MCR5

Behavioural and psychological symptoms of dementia (BPSD), including fear-anxiety- and depressive-like behaviour, are present in Alzheimer's disease (AD), together with memory decline. I₂-imidazoline receptors (I₂-IRs) have been associated with neuropsychiatric and neurodegenerative disorders, further, I₂-IR ligands have demonstrated a neuroprotective role in the central nervous system (CNS). In this study, we assessed the effect of the I₂-IR ligand MCR5 on both cognitive and non-cognitive symptoms in the Senescence accelerated mice prone 8 (SAMP8) mouse model. Oral administration of I₂-IR ligand MCR5 (5 mg/kg/day for four weeks) in 10-month SAMP8 mice ameliorated both BPSD-like phenotype and cognitive decline by attenuating depressive-like behaviour, reducing fear-anxiety-like behaviour and improving cognitive performance using different tasks. Interaction of I₂-IR ligand MCR5 with serotoninergic system did not account for behavioural or cognitive improvement, although changes in molecular pathways underlying depression and anxiety phenotype were observed. MCR5 increased levels of p-AKT, phosphorylated glycogen synthase kinase 3 β (GSK3β) at Ser9 and phosphorylated mammalian target of rapamycin complex 1 (mTORC1) levels in SAMP8 treated mice compared to SAMP8 control. Moreover, MCR5 treatment altered N-methyl-d-aspartate receptor (NMDA) 2B phosphorylation, and decreased the protein levels of phosphorylated cyclin-dependent kinase 5 (p-CDK5) and dopamine- and cyclic adenosine monophosphate (cAMP)-regulated phosphoprotein of Mr 32 kDa phosphorylated at Thr75 (p-DARPP32), with a parallel increase in protein kinase A (PKA) and p-cAMP response element-binding (pCREB) levels. Consistent with these changes MCR5 attenuated neuroinflammation by decreasing expression of pro-inflammatory markers such as Tumor necrosis factor-alpha (Tnf-α), Interleukin 1β (Il-1β), Interleukin 6 (Il-6), and promoted synaptic plasticity by increasing levels of postsynaptic density protein 95 (PSD95) as well as ameliorating tropomyosin-related kinase B (TrkB) and nerve growth factor receptor (NGFR) signalling. Collectively, these results increase the potential of highly selective I₂-IR ligands as therapeutic agents in age-related BPSD and cognitive alterations.

Brain-derived neurotrophic factor fused with a collagen-binding domain inhibits neuroinflammation and promotes neurological recovery of traumatic brain injury mice via TrkB signalling

OBJECTIVES

As one of the vital nutrient factors in central nervous system (CNS), brain-derived neurotrophic factor (BDNF) can significantly attenuate neuron damage and promote neurogenesis. Nevertheless, little research has been conducted on regulating the effect of BDNF on the inflammatory response after traumatic brain injury (TBI).

METHODS

In this study, we used BDNF fused with a collagen-binding domain (CBD-BDNF) to maintain a sufficient concentration of BDNF in the TBI hemisphere, and then, the regulatory effects of BDNF and CBD-BDNF on the inflammatory response of microglia were investigated both on a TBI mice model in vivo and LPS-stimulated microglia experiment in vitro.

KEY FINDINGS

The results revealed that BDNF and CBD-BDNF had similar effects on attenuating the pro-inflammatory reactions but promoting anti-inflammatory responses of microglia induced by LPS in vitro. Furthermore, CBD-BDNF significantly improved the neurological behaviours of TBI mice and alleviated the inflammatory reaction after TBI, while BDNF had weaker effects compared with those of CBD-BDNF. Additionally, the TrkB inhibitor K252a significantly inhibited the above effects of CBD-BDNF.

CONCLUSIONS

In conclusion, CBD-BDNF can promote the anti-inflammatory function of microglia and neurological recovery of TBI mice through TrkB signalling.

Prebiotics and probiotics as potential therapy for cognitive impairment

Cognitive functions, such as learning and memory, may be impaired during aging. Age-related cognitive impairment is associated with selective neuronal loss, oxidative changes that lead to microglia activation and neuroinflammation. In addition, it is associated to alteration reduction in trophic factors affecting neurogenesis and synaptic plasticity. In recent years, attention has been paid to the relationship between gut microbiota and brain. In aging, there is an alteration in microbiota, gut microbiota diversity is perturbed with an increase in pathogenic bacteria at the expense of beneficial ones. Dysbiosis may lead to chronic inflammation, and a decrease in bacteria metabolites such as short-chain fatty acids which have been related to an upregulation of neurotrophic factors. Supplementation with prebiotics and probiotics can modulate gut microbiota, returning it to a more physiological state; thus, they may be considered as a possible treatment for age-related cognitive impairment.

miR-496 suppress tumorigenesis via targeting BDNF-mediated PI3K/Akt signaling pathway in non-small cell lung cancer

microRNA-496 (miR-496) was found expressed abnormally in non-small cell lung cancer (NSCLC). But the study about the role of miR-496 on NSCLC was not satisfactory in date. Therefore, here we designed to explore the role of miR-496 and the probable internal mechanism in tumorigenesis of NSCLC. Increasing miR-496 both in NSCLC patients and cell lines could significantly restrained cell proliferation. For farther researching the regulation mechanism of miR-496 on NSCLC, we screen Brain derived neurotrophic factor (BDNF) as a potential target of miR-496 by bioinformatic methods and predicted a possible target of miR-496 in the 3'untranslated region (UTR) of miR-496. In clinical patients and most NSCLC cell lines including H1650, H292, H1944 and A549, increasing expression of miR-496 suppressed tumor growth via inactivating BDNF-mediated PI3K/Akt signaling pathway activation. In a word, our fingdings first represent a mechanism of miR-496 on NSCLC tumor growth via inactivating BDNF-mediated PI3K/Akt signaling pathway.

Therapeutic exercise accompanied by neuronal modulation to enhance neurotrophic factors in the brain with central nervous system disorders

Exercise is a primary therapeutic regimen in physical therapy to rehabilitate the motor function of patients with central nervous system (CNS) disorders such as cerebrovascular accident (CVA). Furthermore, exercise positively contributes to cognitive function related to neuroplasticity and neuroprotection in the hippocampus. Neurotrophins play a crucial role in neuroplasticity, neurogenesis, and neuroprotection in the CNS. Exercise enhances the expression of neurotrophins in the brain. Thus, novel regimens for kinesiotherapy in CNS disorders to further enhance exercise-induced expression are expected. In this review, we described three novel regimens for kinesiotherapy in CNS disorders based on the interaction between exercise and pharmacological treatment with the idea of "inhibition of inhibition" in the CNS.

Detection of BDNF-Related Proteins in Human Perilymph in Patients With Hearing Loss

The outcome of cochlear implantation depends on multiple variables including the underlying health of the cochlea. Brain derived neurotrophic factor (BDNF) has been shown to support spiral ganglion neurons and to improve implant function in animal models. Whether endogenous BDNF or BDNF-regulated proteins can be used as biomarkers to predict cochlear health and implant outcome has not been investigated yet. Gene expression of BDNF and downstream signaling molecules were identified in tissue of human cochleae obtained from normal hearing patients (n = 3) during skull base surgeries. Based on the gene expression data, bioinformatic analysis was utilized to predict the regulation of proteins by BDNF. The presence of proteins corresponding to these genes was investigated in perilymph (n = 41) obtained from hearing-impaired patients (n = 38) during cochlear implantation or skull base surgery for removal of vestibular schwannoma by nanoscale liquid chromatography coupled to tandem mass spectrometry (nano LC-MS/MS). Analyzed by mass spectrometry were 41 perilymph samples despite three patients undergoing bilateral cochlear implantation. These particular BDNF regulated proteins were not detectable in any of the perilymph samples. Subsequently, targeted analysis of the perilymph proteome data with Ingenuity Pathway Analysis (IPA) identified further proteins in human perilymph that could be regulated by BDNF. These BDNF regulated proteins were correlated to the presence of residual hearing (RH) prior to implantation and to the performance data with the cochlear implant after 1 year. There was overall a decreased level of expression of BDNF-regulated proteins in profoundly hearing-impaired patients compared to patients with some RH. Phospholipid transfer protein was positively correlated to the preoperative hearing level of the patients. Our data show that combination of gene expression arrays and bioinformatic analysis can aid in the prediction of downstream signaling proteins related to the BDNF pathway. Proteomic analysis of perilymph may help to identify the presence or absence of these molecules in the diseased organ. The impact of such prediction algorithms on diagnosis and treatment needs to be established in further studies.

Enriched environment regulates thymocyte development and alleviates experimental autoimmune encephalomyelitis in mice

Environmental and social factors have profound impacts on immune homeostasis. Our work on environmental enrichment (EE) has revealed a novel anti-obesity and anticancer phenotype associated with enhanced activity of CD8+ cytotoxic T lymphocytes in secondary lymphoid tissues. Here we investigated how an EE modulated thymus and thymocyte development. EE decreased thymus mass and cellularity, decreased the double positive thymocyte population, increased the proportion of CD8+ T cells, reduced the CD4:CD8 ratio, and downregulated CD69 expression in T cells. In a model of multiple sclerosis: experimental autoimmune encephalomyelitis (EAE), EE alleviated symptoms, inhibited spinal cord inflammation through regulation of type 1 T-helper cells mediated by glucocorticoid receptor signaling, and prevented EAE-induced thymic disturbance. Our mechanistic studies demonstrated that hypothalamic BDNF activated a hypothalamic-pituitary-adrenal axis mediating the EE's thymic effects. Our results indicate that a lifestyle intervention links the nervous, endocrine, and adaptive immune system, allowing the body to adapt to internal and external environments.

Loss of Shp2 Rescues BDNF/TrkB Signaling and Contributes to Improved Retinal Ganglion Cell Neuroprotection

Glaucoma is characterized by the loss of retinal ganglion cells (RGC), and accordingly the preservation of RGCs and their axons has recently attracted significant attention to improve therapeutic outcomes in the disease. Here, we report that Src homology region 2-containing protein tyrosine phosphatase 2 (Shp2) undergoes activation in the RGCs, in animal model of glaucoma as well as in the human glaucoma tissues and that Shp2 dephosphorylates tropomyosin receptor kinase B (TrkB) receptor, leading to reduced BDNF/TrkB neuroprotective survival signaling. This was elucidated by specifically modulating Shp2 expression in the RGCs in vivo, using adeno-associated virus serotype 2 (AAV2) constructs. Shp2 upregulation promoted endoplasmic reticulum (ER) stress and apoptosis, along with functional and structural deficits in the inner retina. In contrast, loss of Shp2 decelerated the loss of RGCs, preserved their function, and suppressed ER stress and apoptosis in glaucoma. This report constitutes the first identification of Shp2-mediated TrkB regulatory mechanisms in the RGCs that can become a potential therapeutic target in both glaucoma and other neurodegenerative disorders.

BDNF release and signaling are required for the antidepressant actions of GLYX-13

Conventional antidepressant medications, which act on monoaminergic systems, display significant limitations, including a time lag of weeks to months and low rates of therapeutic efficacy. GLYX-13 is a novel glutamatergic compound that acts as an N-methyl-D-aspartate (NMDA) modulator with glycine-like partial agonist properties; like the NMDA receptor antagonist ketamine GLYX-13 produces rapid antidepressant actions in depressed patients and in preclinical rodent models. However, the mechanisms underlying the antidepressant actions of GLYX-13 have not been characterized. Here we use a combination of neutralizing antibody (nAb), mutant mouse and pharmacological approaches to test the role of brain-derived neurotrophic factor-tropomyosin-related kinase B (BDNF-TrkB) signaling in the actions of GLYX-13. The results demonstrate that the antidepressant effects of GLYX-13 are blocked by intra-medial prefrontal cortex (intra-mPFC) infusion of an anti-BDNF nAb or in mice with a knock-in of the BDNF Val66Met allele, which blocks the processing and activity-dependent release of BDNF. We also demonstrate that pharmacological inhibitors of BDNF-TrkB signaling or of L-type voltage-dependent Ca2+ channels (VDCCs) block the antidepressant behavioral actions of GLYX-13. Finally, we examined the role of the Rho GTPase proteins by injecting a selective inhibitor into the mPFC and found that activation of Rac1 but not RhoA is involved in the antidepressant effects of GLYX-13. Together, these findings indicate that enhanced release of BDNF through exocytosis caused by activation of VDCCs and subsequent TrkB-Rac1 signaling is required for the rapid and sustained antidepressant effects of GLYX-13.

Increasing Brain-Derived Neurotrophic Factor (BDNF) in medial prefrontal cortex selectively reduces excessive drinking in ethanol dependent mice

The neurotrophin Brain-Derived Neurotrophic Factor (BDNF) has been implicated in a number of neuropsychiatric disorders, including alcohol use disorder. Studies have shown that BDNF activity in cortical regions, such as the medial prefrontal cortex (mPFC) mediates various ethanol-related behaviors. We previously reported a significant down-regulation in Bdnf mRNA in mPFC following chronic ethanol exposure compared to control mice. The present study was conducted to extend these findings by examining whether chronic ethanol treatment reduces BDNF protein expression in mPFC and whether reversing this deficit via direct injection of BDNF or viral-mediated overexpression of BDNF in mPFC alters voluntary ethanol consumption in dependent and nondependent mice. Repeated cycles of chronic intermittent ethanol (CIE) exposure was employed to model ethanol dependence, which produces robust escalation of ethanol intake. Results indicated that CIE treatment significantly increased ethanol intake and this was accompanied by a significant decrease in BDNF protein in mPFC that lasted at least 72 h after CIE exposure. In a separate study, once dependence-related increased drinking was established, bilateral infusion of BDNF (0, 0.25, 0.50 μg) into mPFC significantly decreased ethanol intake in a dose-related manner in dependent mice but did not affect moderate drinking in nondependent mice. In a third study, viral-mediated overexpression of BDNF in mPFC prevented escalation of drinking in dependent mice but did not alter intake in nondependent mice. Collectively, these results provide evidence that adaptations in cortical (mPFC) BDNF activity resulting from chronic ethanol exposure play a role in mediating excessive ethanol drinking associated with dependence.

A network map of thrombopoietin signaling

Thrombopoietin (THPO), also known as megakaryocyte growth and development factor (MGDF), is a cytokine involved in the production of platelets. THPO is a glycoprotein produced by liver and kidney. It regulates the production of platelets by stimulating the differentiation and maturation of megakaryocyte progenitors. It acts as a ligand for MPL receptor, a member of the hematopoietic cytokine receptor superfamily and is essential for megakaryocyte maturation. THPO binding induces homodimerization of the receptor which results in activation of JAKSTAT and MAPK signaling cascades that subsequently control cellular proliferation, differentiation and other signaling events. Despite the importance of THPO signaling in various diseases and biological processes, a detailed signaling network of THPO is not available in any publicly available database. Therefore, in this study, we present a resource of signaling events induced by THPO that was manually curated from published literature on THPO. Our manual curation of thrombopoietin pathway resulted in identification of 48 molecular associations, 66 catalytic reactions, 100 gene regulation events, 19 protein translocation events and 43 activation/inhibition reactions that occur upon activation of thrombopoietin receptor by THPO. THPO signaling pathway is made available on NetPath, a freely available human signaling pathway resource developed previously by our group. We believe this resource will provide a platform for scientific community to accelerate further research in this area on potential therapeutic interventions.

The 5-Hydroxytryptamine signaling map: an overview of serotonin-serotonin receptor mediated signaling network

The monoamine neurotransmitter, 5-Hydroxytryptamine or serotonin, is derived from tryptophan and synthesized both centrally and systemically. Fourteen structurally and functionally distinct receptor subtypes have been identified for serotonin, each of which mediates the neurotransmitter's effects through a range of downstream signaling molecules and effectors. Although it is most frequently described for its role in the etiology of neuropsychiatric and mood disorders, serotonin has been implicated in a slew of fundamental physiological processes, including apoptosis, mitochondrial biogenesis, cell proliferation and migration. Its roles as the neurotransmitter have also emerged in pathogenic conditions ranging from anorexia nervosa to cancer. This has necessitated the understanding of the signaling mechanisms underlying the serotonergic system, which led us to construct a consolidative pathway map, which will provide as a resource for future biomedical investigation on this pathway. Using a set of stringent NetPath annotation criteria, we manually curated molecular reactions associated with serotonin and its receptors from publicly available literature; the reaction categories included molecular associations, activation/inhibition, post-translation modification, transport, and gene regulation at transcription and translational level. We identified 90 molecules in serotonin-serotonin receptor pathway. We submitted the curated data to NetPath, a publicly available database of human signaling pathways, in order to enable the wider scientific community to readily access data and contribute further to this pathway.

Proliferative role of BDNF/TrkB signaling is associated with anoikis resistance in cervical cancer

Brain-derived neurotrophic factor (BDNF) is known as one of the members of the neurotropin family. BDNF-induced activation of its receptor tyrosine kinase B (TrkB) is associated with anoikis tolerance, tumor progression and poor prognosis in many types of malignancy. However, to the best of our knowledge, there are no reports describing the contribution of the BDNF/TrkB axis to cervical cancer. BDNF and TrKB expression in cervical cancer (CC) tissues and adjacent normal tissues from 87 patients were analyzed by immunohistochemistry, western blot analysis and quantitative PCR assays and the results showed that they were significantly higher in cancer tissues than that in normal adjacent tissues, respectively. Higher expression rates of BDNF and TrKB were observed in stage IIB or higher and BDNF expression was positively associated with lymph node metastasis. Notably, a high expression of TrKB may be contributed to poor survival time, which confirmed by Kaplan-Meier analysis. Compared to the corresponding CC cell lines, HeLa, SiHa, CASKI, C4-1 and C-33a, BDNF and TrKB expression was enhanced in anoikis-like apoptotic tolerance (AAT), a cell model established from cervical cancer cell lines. AAT cells showed a higher proliferation activity compared with CC cell lines, which was confirmed by a shorter G0/G1 phase, elevated cyclin A, cyclin D1 and c-myc, decreased caspase-3 and Bax, and increased Bcl-2. By contrast, the knockdown of TrKB expression reversed these changes in AAT cells, induced G0/G1 arrest and suppressed proliferation activity. The results of the present study show that PI3K/Akt signaling is involved in the BDNF/TrKB-induced proliferation of AAT cells in cervical cancer. These findings indicate that BDNF/TrKB pathway is a potential target for the treatment of cervical cancer.

The Role of Fluoxetine in Activating Wnt/β-Catenin Signaling and Repressing β-Amyloid Production in an Alzheimer Mouse Model

Fluoxetine (FLX) is one of the selective serotonin reuptake inhibitors (SSRIs) antidepressants, which could be used to relieve depression and anxiety among AD patients. This study was designed to search for new mechanisms by which fluoxetine could activate Wnt/β-catenin signaling pathway and reduce amyloidosis in AD brain. Fluoxetine was administered via intragastric injection to APP/tau/PS1 mouse model of Alzheimer’s disease (3×Tg-AD) mice for 4 months. In the hippocampus of AD mouse model, there could be observed neuronal apoptosis, as well as an increase in Aβ (amyloid-β) production. Moreover, there is a strong association between down-regulation of Wnt/β-catenin signaling and the alteration of AD pathology. The activity of protein phosphatases of type 2A (PP2A) could be significantly enhanced by the treatment of fluoxetine. The activation of PP2A, caused by fluoxetine, could then play a positive role in raising the level of active β-catenin, and deliver a negative impact in GSK3β activity in the hippocampal tissue. Both the changes mentioned above would lead to the activation of Wnt/β-catenin signaling. Meanwhile, fluoxetine treatment would reduce APP cleavage and Aβ generation. It could also prevent apoptosis in 3×Tg-AD primary neuronal cell, and have protective effects on neuron synapse. These findings imply that Wnt/β-catenin signaling could be a potential target outcome for AD prevention, and fluoxetine has the potential to be a promising drug in both AD prevention and treatment.

microRNA-107 inhibits gastric cancer cell proliferation and metastasis by targeting PI3K/AKT pathway

The present study was aimed to investigate the effect of miR-107 transfection on gastric cancer cell growth. Results from qRT-PCR revealed that level of miR-107 in SGC-7901 and MKN1 cell lines was down-regulated in comparison to the normal cells, GES-1. CCK-8 assay revealed a significant reduction in the proliferation of SGC-7901 cells on transfection with miR-107. The tumor growth was very slow in the mice implanted with SGC-7901/miR-107 compared to those bearing SGC-7901/miR-NC. In SGC-7901 cells metastasis potential after miR-107 transfection was examined using wound-healing and Transwell invasion assays. The migration as well as invasion potential of SGC-7901 cells was significantly lower on transfection with miR-107. The activity of luciferase was reduced markedly in SGC-7901 cells co-transfected with miR-107 mimic compared to miR-NC. However, miR-107 mimic co-transfection did not affect the luciferase activity in SGC-7901 cells bearing mutant-type BDNF 3'UTR. Western blot assay showed that miR-107 overexpression causes inhibition of BDNF mRNA and protein expression in SGC-7901 cells. The CCK8 assay showed that pBDNF transfection prevented miR-107 mediated inhibition of SGC-7901 cell proliferation. miR-107 mimic transfection inhibited expression of BDNF and activation of PI3K (p-PI3K) and AKT (p-AKT) in SGC-7901 cells. In order to confirm whether activation of PI3K and AKT by miR-107 mimic involves inhibition of BDNF, the cells were co-transfected with si-BDNF. The results revealed that si-BDNF transfection led to inhibition of BDNF expression and PI3K and AKT activation in SGC-7901 cells. In summary, the present study demonstrates that miR-107 expression inhibits proliferation and metastasis in gastric cancer cells. Therefore, miR-107 acts as tumor inhibitor for gastric cancer through targeting BDNF expression. Thus miR-107 can be used for treatment of gastric cancer.

Proteomic Analysis of the Human Olfactory Bulb

The importance of olfaction to human health and disease is often underappreciated. Olfactory dysfunction has been reported in association with a host of common complex diseases, including neurological diseases such as Alzheimer's disease and Parkinson's disease. For health, olfaction or the sense of smell is also important for most mammals, for optimal engagement with their environment. Indeed, animals have developed sophisticated olfactory systems to detect and interpret the rich information presented to them to assist in day-to-day activities such as locating food sources, differentiating food from poisons, identifying mates, promoting reproduction, avoiding predators, and averting death. In this context, the olfactory bulb is a vital component of the olfactory system receiving sensory information from the axons of the olfactory receptor neurons located in the nasal cavity and the first place that processes the olfactory information. We report in this study original observations on the human olfactory bulb proteome in healthy subjects, using a high-resolution mass spectrometry-based proteomic approach. We identified 7750 nonredundant proteins from human olfactory bulbs. Bioinformatics analysis of these proteins showed their involvement in biological processes associated with signal transduction, metabolism, transport, and olfaction. These new observations provide a crucial baseline molecular profile of the human olfactory bulb proteome, and should assist the future discovery of biomarker proteins and novel diagnostics associated with diseases characterized by olfactory dysfunction.

Effects of aerobic training, resistance training, or both on brain-derived neurotrophic factor in adolescents with obesity: The hearty randomized controlled trial

Brain derived neurotrophic factor (BDNF) is a protein that plays a critical role in modulating cognition in animals and humans. Aerobic exercise often increases BDNF in adults, but effects of this exercise modality and others among adolescents remain uncertain. This study examined the effects of aerobic training, resistance training, and combined training on resting serum BDNF levels in adolescents with overweight and obesity. After a 4-week pre-randomization treatment, 304 post-pubertal, adolescents with overweight or obesity (70% females) aged 14-18 years were randomized to one of four groups for 22 weeks: aerobic training (N = 75), resistance training (N = 78), combined aerobic and resistance training (N = 75), or non-exercising control (N = 76). All participants received dietary counseling targeting a daily energy deficit of 250 kcal. The exercise prescription was 4 times per week, progressing to 45 min/session for the aerobic and resistance groups and 90 min/session for the combined group. Resting serum BDNF levels were measured at baseline and 6-months. Results showed that in both intention-to-treat (ITT) and per protocol (≥70% adherence to prescribed sessions) analyses, there were no significant within- or between-group changes in BDNF. Findings indicate that aerobic training, resistance training or their combination did change serum BDNF levels in adolescents with overweight and obesity.

TRIAL REGISTRATION

ClinicalTrials.Gov NCT00195858 http://clinicaltrials.gov/show/NCT00195858, September 12, 2005 (Funded by the Canadian Institutes of Health Research).

MicroRNA-497 inhibits thyroid cancer tumor growth and invasion by suppressing BDNF

miR-497 reportedly plays critical roles in tumor development and progression in many types of cancers. We therefore investigated the function and underlying mechanism of miR-497 in thyroid cancer. We found that miR-497 is downregulated in thyroid cancer tissues, and that miR-497 levels are negatively correlated with advanced clinical stage and lymph node metastasis. Overexpressed miR-497 suppressed thyroid cancer cell proliferation, colony formation, migration, and invasion in vitro, and inhibited tumorigenesis in vivo. Moreover, brain-derived neurotrophic factor (BDNF), a known oncogene, was confirmed as a direct target of miR-497 in thyroid cancer cells. miR-497 overexpression suppressed BDNF expression and its downstream pathway(PI3K/AKT)in vitro and in vivo. BDNF levels were upregulated and inversely correlated with miR-497 levels in human thyroid cancer specimens. Rescue experiments showed that forced overexpression of BDNF effectively reversed the tumor suppressive functions of miR-497. These results show that miR-497 is a thyroid cancer tumor suppressor that acts by repressing BDNF.

Palmitoylethanolamide Dampens Reactive Astrogliosis and Improves Neuronal Trophic Support in a Triple Transgenic Model of Alzheimer's Disease: In Vitro and In Vivo Evidence

Alzheimer's disease (AD) is a neurodegenerative disorder responsible for the majority of dementia cases in elderly people. It is widely accepted that the main hallmarks of AD are not only senile plaques and neurofibrillary tangles but also reactive astrogliosis, which often precedes detrimental deposits and neuronal atrophy. Such phenomenon facilitates the regeneration of neural networks; however, under some circumstances, like in AD, reactive astrogliosis is detrimental, depriving neurons of the homeostatic support, thus contributing to neuronal loss. We investigated the presence of reactive astrogliosis in 3×Tg-AD mice and the effects of palmitoylethanolamide (PEA), a well-documented anti-inflammatory molecule, by in vitro and in vivo studies. In vitro results revealed a basal reactive state in primary cortical 3×Tg-AD-derived astrocytes and the ability of PEA to counteract such phenomenon and improve viability of 3×Tg-AD-derived neurons. In vivo observations, performed using ultramicronized- (um-) PEA, a formulation endowed with best bioavailability, confirmed the efficacy of this compound. Moreover, the schedule of treatment, mimicking the clinic use (chronic daily administration), revealed its beneficial pharmacological properties in dampening reactive astrogliosis and promoting the glial neurosupportive function. Collectively, our results encourage further investigation on PEA effects, suggesting it as an alternative or adjunct treatment approach for innovative AD therapy.

Brain-derived neurotrophic factor: a mediator of inflammation-associated neurogenesis in Alzheimer's disease

In early- or late-onset Alzheimer's disease (AD), inflammation, which is triggered by pathologic conditions, influences the progression of neurodegeneration. Brain-derived neurotrophic factor (BDNF) has emerged as a crucial mediator of neurogenesis, because it exhibits a remarkable activity-dependent regulation of expression, which suggests that it may link inflammation to neurogenesis. Emerging evidence suggests that acute and chronic inflammation in AD differentially modulates neurotrophin functions, which are related to the roles of inflammation in neuroprotection and neurodegeneration. Recent studies also indicate novel mechanisms of BDNF-mediated neuroprotection, including the modulation of autophagy. Numerous research studies have demonstrated reverse parallel alterations between proinflammatory cytokines and BDNF during neurodegeneration; thus, we hypothesize that one mechanism that underlies the negative impact of chronic inflammation on neurogenesis is the reduction of BDNF production and function by proinflammatory cytokines.

Exercise enhances cognitive function and neurotrophin expression in the hippocampus accompanied by changes in epigenetic programming in senescence-accelerated mice

Aerobic exercise is known to increase expression of neurotrophins, particularly brain-derived neurotrophic factor (BDNF), in the hippocampus and to improve cognitive function. Exercise exerts neuroprotective effects in the hippocampus by inducing epigenetic changes, which play crucial roles in aging and neurodegenerative diseases. Specifically, the activity levels of histone acetyltransferases (HATs) and histone deacetylases (HDACs) regulate histone acetylation and modulate gene transcription. The objective of the present study was to assess the interactive effects of exercise and aging on cognitive function, expression of neurotrophins (BDNF and neurotrophin-4) and their receptors (tyrosine receptor kinase B and p75), and epigenetic regulations, including the activity of HATs and HADCs in the hippocampus. We used the senescence-accelerated mouse (SAM) model, specifically 13-month-old SAM resistant 1(SAMR1) and SAM prone 1 (SAMP1) lines. Mice were distributed into four groups based on accelerated senescence and exercise status. Mice in the exercise groups exercised on a treadmill for approximately 60min a day, 5days a week. Aerobic exercise for 4 weeks improved cognitive function, accompanied by an increase in BDNF expression and a decrease in p75 transcription in both SAMR1 and SAMP1. In addition, the exercise regimen activated both HAT and HDAC in the hippocampus. Therefore, the present study reveals that despite accelerated senescence, long-term exercise improved cognitive function, upregulated the expression of BDNF, and downregulated p75, a receptor involved in apoptotic signaling. Furthermore, long-term exercise enhanced activity of both HAT and HDAC, which may contribute to the transcriptional regulation underlying the improvement of cognitive function.

Neuronal activity-dependent local activation of dendritic unfolded protein response promotes expression of brain-derived neurotrophic factor in cell soma

Unfolded protein response (UPR) has roles not only in resolving the accumulation of unfolded proteins owing to endoplasmic reticulum (ER) stress, but also in regulation of cellular physiological functions. ER stress transducers providing the branches of UPR signaling are known to localize in distal dendritic ER of neurons. These reports suggest that local activation of UPR branches may produce integrated outputs for distant communication, and allow regulation of local events in highly polarized neurons. Here, we demonstrated that synaptic activity‐ and brain‐derived neurotrophic factor (BDNF)‐dependent local activation of UPR signaling could be associated with dendritic functions through retrograde signal propagation by using murine neuroblastoma cell line, Neuro‐2A and primary cultured hippocampal neurons derived from postnatal day 0 litter C57BL/6 mice. ER stress transducer, inositol‐requiring kinase 1 (IRE1), was activated at postsynapses in response to excitatory synaptic activation. Activated dendritic IRE1 accelerated accumulation of the downstream transcription factor, x‐box‐binding protein 1 (XBP1), in the nucleus. Interestingly, excitatory synaptic activation‐dependent up‐regulation of XBP1 directly facilitated transcriptional activation of BDNF. BDNF in turn drove its own expression via IRE1‐XBP1 pathway in a protein kinase A‐dependent manner. Exogenous treatment with BDNF promoted extension and branching of dendrites through the protein kinase A‐IRE1‐XBP1 cascade. Taken together, our findings indicate novel mechanisms for communication between soma and distal sites of polarized neurons that are coordinated by local activation of IRE1‐XBP1 signaling. Synaptic activity‐ and BDNF‐dependent distinct activation of dendritic IRE1‐XBP1 cascade drives BDNF expression in cell soma and may be involved in dendritic extension.

Cover Image for this issue: doi. 10.1111/jnc.14159.