Neuregulins in Neurodegenerative Diseases

Photobiomodulation therapy mitigates depressive-like behaviors by remodeling synaptic links and mitochondrial function

Depression, a multifactorial mental disorder, characterized by cognitive slowing, anxiety, and impaired cognitive function, imposes a significant burden on public health. Photobiomodulation (PBM), involving exposure to sunlight or artificial light at a specific intensity and wavelength for a determined duration, influences brain activity, functional connectivity, and plasticity. It is recognized for its therapeutic efficacy in treating depression, yet its molecular and cellular underpinnings remain obscure. Here, we investigated the impact of PBM with 468 nm light on depression-like behavior and neuronal damage in the chronic unpredictable mild stress (CUMS) murine model, a commonly employed animal model for studying depression. Our results demonstrate that PBM treatment ameliorated behavioral deficits, inhibited neuroinflammation and apoptosis, and notably rejuvenates the hippocampal synaptic function in depressed mice, which may be mainly attributed to the up-regulation of brain-derived neurotrophic factor signaling pathways. In addition, in vitro experiments with a corticosterone-induced hippocampal neuron injury model demonstrate reduced oxidative stress and improved mitochondrial function, further validating the therapeutic potential of PBM. In summary, these findings suggest PBM as a promising, non-invasive treatment for depression, offering insights into its biological mechanisms and potential for clinical application.

The Notch1/Hes1 pathway regulates Neuregulin 1/ErbB4 and participates in microglial activation in rats with VPA-induced autism

The core clinical characteristics of autism, which is a neurodevelopmental disease, involve repetitive behavior and impaired social interactions. Studies have shown that the Notch and Neuregulin1 (NRG1) signaling pathways are abnormally activated in autism, but the mechanism by which these two signaling pathways interact to contribute to the progression of autism has not been determined. Our results suggest that the levels of Notch1, Hes1, NRG1, and phosphorylated ErbB4 in the cerebellum (CB), hippocampus (HC), and prefrontal cortex (PFC) were increased in rats with valproic acid (VPA)-induced autism compared to those in the Con group. However, 3, 5-difluorophenyl-L-alanyl-L-2-phenylglycine tert-butyl (DAPT), which is a Notch pathway inhibitor, ameliorated autism-like behavioral abnormalities and decreased the protein levels of NRG1 and phosphorylated ErbB4 in rats with VPA-induced autism; these results demonstrated that the Notch1/Hes1 pathway could participate in the pathogenesis of autism by regulating the NRG1/ErbB4 signaling pathway. Studies have shown that the Notch pathway regulates microglial differentiation and activation during the onset of neurological disorders and that microglia affect autism-like behavior via synaptic pruning. Therefore, we hypothesized that the Notch1/Hes1 pathway could regulate the NRG1/ErbB4 pathway and thus participate in the development of autism by regulating microglial functions. The present study showed that AG1478, which is an ErbB4 inhibitor, ameliorated the autism-like behaviors in a VPA-induced autism rat model, reduced abnormal microglial activation, and decreased NRG1 and Iba-1 colocalization; however, AG1478 did not alter Notch1/Hes1 activity. These results demonstrated that Notch1/Hes1 may participate in the microglial activation in autism by regulating NRG1/ErbB4, revealing a new mechanism underlying the pathogenesis of autism.

Neuregulin-1 and ALS19 (ERBB4): at the crossroads of amyotrophic lateral sclerosis and cancer

BACKGROUND

Neuregulin-1 (NRG1) is implicated in both cancer and neurologic diseases such as amyotrophic lateral sclerosis (ALS); however, to date, there has been little cross-field discussion between neurology and oncology in regard to these genes and their functions.

MAIN BODY

Approximately 0.15-0.5% of cancers harbor NRG1 fusions that upregulate NRG1 activity and hence that of the cognate ERBB3/ERBB4 (HER3/HER4) receptors; abrogating this activity with small molecule inhibitors/antibodies shows preliminary tissue-agnostic anti-cancer activity. Notably, ERBB/HER pharmacologic suppression is devoid of neurologic toxicity. Even so, in ALS, attenuated ERBB4/HER4 receptor activity (due to loss-of-function germline mutations or other mechanisms in sporadic disease) is implicated; indeed, ERBB4/HER4 is designated ALS19. Further, secreted-type NRG1 isoforms may be upregulated (perhaps via a feedback loop) and could contribute to ALS pathogenesis through aberrant glial cell stimulation via enhanced activity of other (e.g., ERBB1-3/HER1-3) receptors and downstream pathways. Hence, pan-ERBB inhibitors, already in use for cancer, may be agents worthy of testing in ALS.

CONCLUSION

Common signaling cascades between cancer and ALS may represent novel therapeutic targets for both diseases.

Anti-inflammatory effects of neuregulin-1 in HaCaT keratinocytes and atopic dermatitis-like mice stimulated with Der p 38

Neuregulin (NRG)-1 plays fundamental roles in several organ systems after binding to its receptors, ErbB2 and ErbB4. This study examines the role of NRG-1 in atopic dermatitis (AD), a chronic skin disease that causes dryness, pruritus, and inflammation. In mice administered Der p 38, the skin presents AD-like symptoms including filaggrin downregulation and infiltration of neutrophils and eosinophils. Noticeably, there is an increased expression of NRG-1, ErbB2, and ErbB4 in the skin. Upregulation of these proteins is significantly correlated to the clinical skin severity score. In human keratinocyte HaCaT cells, exposure to Der p 38 decreased filaggrin expression, and NRG-1 alone had no effect on the expression. However, co-treatment of Der p 38 with NRG-1 enhanced the filaggrin expression decreased by Der p 38. Pre-treatment with AG879 (an ErbB2 inhibitor) or ErbB4 siRNA blocked the recovery of filaggrin expression in the cells after co-treatment with Der p 38 and NRG-1. Der p 38 treatment enhanced the secretion of interleukin-6 (IL-6), IL-8, and monocyte chemoattractant protein-1 (MCP-1). Co-treatment of Der p 38 with NRG-1 lowered the cytokine secretion increased by Der p 38, although NRG-1 alone was not effective on cytokine alteration. Neutrophil apoptosis was not altered by NRG-1 or supernatants of cells treated with NRG-1, but the cell supernatants co-treated with Der p 38 and NRG-1 blocked the anti-apoptotic effects of Der p 38-treated supernatants on neutrophils, which was involved in the activation of caspase 9 and caspase 3. Taken together, we determined that NRG-1 has anti-inflammatory effects in AD triggered by Der p 38. These results will pave the way to understanding the functions of NRG-1 and in the future development of AD treatment.

Unraveling the intercellular communication disruption and key pathways in Alzheimer's disease: an integrative study of single-nucleus transcriptomes and genetic association

BACKGROUND

Recently, single-nucleus RNA-seq (snRNA-seq) analyses have revealed important cellular and functional features of Alzheimer's disease (AD), a prevalent neurodegenerative disease. However, our knowledge regarding intercellular communication mediated by dysregulated ligand-receptor (LR) interactions remains very limited in AD brains.

METHODS

We systematically assessed the intercellular communication networks by using a discovery snRNA-seq dataset comprising 69,499 nuclei from 48 human postmortem prefrontal cortex (PFC) samples. We replicated the findings using an independent snRNA-seq dataset of 56,440 nuclei from 18 PFC samples. By integrating genetic signals from AD genome-wide association studies (GWAS) summary statistics and whole genome sequencing (WGS) data, we prioritized AD-associated Gene Ontology (GO) terms containing dysregulated LR interactions. We further explored drug repurposing for the prioritized LR pairs using the Therapeutic Targets Database.

RESULTS

We identified 190 dysregulated LR interactions across six major cell types in AD PFC, of which 107 pairs were replicated. Among the replicated LR signals, we found globally downregulated communications in the astrocytes-to-neurons signaling axis, characterized, for instance, by the downregulation of APOE-related and Calmodulin (CALM)-related LR interactions and their potential regulatory connections to target genes. Pathway analyses revealed 44 GO terms significantly linked to AD, highlighting Biological Processes such as 'amyloid precursor protein processing' and 'ion transmembrane transport,' among others. We prioritized several drug repurposing candidates, such as cromoglicate, targeting the identified dysregulated LR pairs.

CONCLUSIONS

Our integrative analysis identified key dysregulated LR interactions in a cell type-specific manner and the associated GO terms in AD, offering novel insights into potential therapeutic targets involved in disrupted cell-cell communication in AD.

Deep brain stimulation of thalamic nucleus reuniens promotes neuronal and cognitive resilience in an Alzheimer's disease mouse model

The mechanisms that confer cognitive resilience to Alzheimer's Disease (AD) are not fully understood. Here, we describe a neural circuit mechanism underlying this resilience in a familial AD mouse model. In the prodromal disease stage, interictal epileptiform spikes (IESs) emerge during anesthesia in the CA1 and mPFC regions, leading to working memory disruptions. These IESs are driven by inputs from the thalamic nucleus reuniens (nRE). Indeed, tonic deep brain stimulation of the nRE (tDBS-nRE) effectively suppresses IESs and restores firing rate homeostasis under anesthesia, preventing further impairments in nRE-CA1 synaptic facilitation and working memory. Notably, applying tDBS-nRE during the prodromal phase in young APP/PS1 mice mitigates age-dependent memory decline. The IES rate during anesthesia in young APP/PS1 mice correlates with later working memory impairments. These findings highlight the nRE as a central hub of functional resilience and underscore the clinical promise of DBS in conferring resilience to AD pathology by restoring circuit-level homeostasis.

Prevention of Alzheimer Pathology by Blocking Neuregulin Signaling on Microglia

Plaque formation, microglial activation, and synaptic loss are pathologic hallmarks of Alzheimer's disease; however, removing plaques has had little clinical benefit. Here, we show that neuregulin-1, a glial growth factor, induces inflammatory cytokines and promotes phagocytic activity in vitro and augments microglial activation and plaque formation in 5XFAD Alzheimer's mice. Brain-specific targeting of neuregulin-1 by intraventricular delivery of a novel neuregulin-1 fusion protein antagonist, GlyB4, significantly alters microglial morphology and function to a nonpathogenic morphology in early-stage 5XFAD mice and prevents plaques from forming. Once plaques have already formed, GlyB4 reduces new plaque formation and prevents synaptic loss. Selective, targeted disruption of neuregulin-1 signaling on brain microglia with GlyB4 could be a novel "upstream" approach to slow or stop disease progression in Alzheimer's disease.

Research on ferroptosis as a therapeutic target for the treatment of neurodegenerative diseases

Ferroptosis is an iron- and lipid peroxidation (LPO)-mediated programmed cell death type. Recently, mounting evidence has indicated the involvement of ferroptosis in neurodegenerative diseases, especially in Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and so on. Treating ferroptosis presents opportunities as well as challenges for neurodegenerative diseases. This review provides a comprehensive overview of typical features of ferroptosis and the underlying mechanisms that contribute to its occurrence, as well as their implications in the pathogenesis and advancement of major neurodegenerative disorders. Meanwhile, we summarize the utilization of ferroptosis inhibition in both experimental and clinical approaches for the treatment of major neurodegenerative disorders. In addition, we specifically summarize recent advances in developing therapeutic means targeting ferroptosis in these diseases, which may guide future approaches for the effective management of these devastating medical conditions.

Integrated analysis of proteomics, epigenomics and metabolomics data revealed divergent pathway activation patterns in the recent versus chronic post-traumatic stress disorder

Metabolomics, proteomics and DNA methylome assays, when done in tandem from the same blood sample and analyzed together, offer an opportunity to evaluate the molecular basis of post-traumatic stress disorder (PTSD) course and pathogenesis. We performed separate metabolomics, proteomics, and DNA methylome assays on blood samples from two well-characterized cohorts of 159 active duty male participants with relatively recent onset PTSD (<1.5 years) and 300 male veterans with chronic PTSD (>7 years). Analyses of the multi-omics datasets from these two independent cohorts were used to identify convergent and distinct molecular profiles that might constitute potential signatures of severity and progression of PTSD and its comorbid conditions. Molecular signatures indicative of homeostatic processes such as signaling and metabolic pathways involved in cellular remodeling, neurogenesis, molecular safeguards against oxidative stress, metabolism of polyunsaturated fatty acids, regulation of normal immune response, post-transcriptional regulation, cellular maintenance and markers of longevity were significantly activated in the active duty participants with recent PTSD. In contrast, we observed significantly altered multimodal molecular signatures associated with chronic inflammation, neurodegeneration, cardiovascular and metabolic disorders, and cellular attritions in the veterans with chronic PTSD. Activation status of signaling and metabolic pathways at the early and late timepoints of PTSD demonstrated the differential molecular changes related to homeostatic processes at its recent and multi-system syndromes at its chronic phase. Molecular alterations in the recent PTSD seem to indicate some sort of recalibration or compensatory response, possibly directed in mitigating the pathological trajectory of the disorder.

Tracking cell-type-specific temporal dynamics in human and mouse brains

Progenitor cells are critical in preserving organismal homeostasis, yet their diversity and dynamics in the aged brain remain underexplored. We introduced TrackerSci, a single-cell genomic method that combines newborn cell labeling and combinatorial indexing to characterize the transcriptome and chromatin landscape of proliferating progenitor cells in vivo. Using TrackerSci, we investigated the dynamics of newborn cells in mouse brains across various ages and in a mouse model of Alzheimer's disease. Our dataset revealed diverse progenitor cell types in the brain and their epigenetic signatures. We further quantified aging-associated shifts in cell-type-specific proliferation and differentiation and deciphered the associated molecular programs. Extending our study to the progenitor cells in the aged human brain, we identified conserved genetic signatures across species and pinpointed region-specific cellular dynamics, such as the reduced oligodendrogenesis in the cerebellum. We anticipate that TrackerSci will be broadly applicable to unveil cell-type-specific temporal dynamics in diverse systems.

Unraveling the intercellular communication disruption and key pathways in Alzheimer's disease: An integrative study of single-nucleus transcriptomes and genetic association

Background

Recently, single-nucleus RNA-seq (snRNA-seq) analyses have revealed important cellular and functional features of Alzheimer's disease (AD), a prevalent neurodegenerative disease. However, our knowledge regarding intercellular communication mediated by dysregulated ligand-receptor (LR) interactions remains very limited in AD brains.

Methods

We systematically assessed the intercellular communication networks by using a discovery snRNA-seq dataset comprising 69,499 nuclei from 48 human postmortem prefrontal cortex (PFC) samples. We replicated the findings using an independent snRNA-seq dataset of 56,440 nuclei from 18 PFC samples. By integrating genetic signals from AD genome-wide association studies (GWAS) summary statistics and whole genome sequencing (WGS) data, we prioritized AD-associated Gene Ontology (GO) terms containing dysregulated LR interactions. We further explored drug repurposing for the prioritized LR pairs using the Therapeutic Targets Database.

Results

We identified 316 dysregulated LR interactions across six major cell types in AD PFC, of which 210 pairs were replicated. Among the replicated LR signals, we found globally downregulated communications in astrocytes-to-neurons signaling axis, characterized, for instance, by the downregulation of APOE-related and Calmodulin (CALM)-related LR interactions and their potential regulatory connections to target genes. Pathway analyses revealed 60 GO terms significantly linked to AD, highlighting Biological Processes such as 'amyloid precursor protein processing' and 'ion transmembrane transport', among others. We prioritized several drug repurposing candidates, such as cromoglicate, targeting the identified dysregulated LR pairs.

Conclusions

Our integrative analysis identified key dysregulated LR interactions in a cell type-specific manner and the associated GO terms in AD, offering novel insights into potential therapeutic targets involved in disrupted cell-cell communication in AD.

Astragaloside IV ameliorates radiation-induced nerve cell damage by activating the BDNF/TrkB signaling pathway

Radiation can induce nerve cell damage. Synapse connectivity and functionality are thought to be the essential foundation of all cognitive functions. Therefore, treating and preventing damage to synaptic structure and function is an urgent challenge. Astragaloside IV (AS-IV) is a glycoside extracted from Astragalus membranaceus (Fisch.). Bunge is a widely used traditional Chinese medicine in China with various pharmacological properties, including protective effects on the central nervous system (CNS). In this study, the effect of AS-IV on synapse damage and BDNF/TrkB signaling pathway in radiated C57BL/6 mice with X-rays was investigated. PC12 cells and primary cortical neurons were exposed to UVA in vitro. Open field test and rotarod test were used to observe the effects of AS-IV on the motor and explore the abilities of radiated mice. The pathological changes in the brain were observed by hematoxylin and eosin and Nissl staining. Immunofluorescence analysis was used to detect the synapse damage. The expressions of the BDNF/TrkB pathway and neuroprotection-related molecules were detected by Western blotting and Quantitative-RTPCR, respectively. The results showed that AS-IV could improve the motor and explore abilities of radiated mice, reduce pathological damage to the cortex, enhance neuroprotection functions, and activate BDNF/TrkB pathway. In conclusion, AS-IV could relieve radiation-induced synapse damage, at least partly through the BDNF/TrkB pathway.

Neuroprotective Effects of Zerumbone on H2O2-Induced Oxidative Injury in Human Neuroblastoma SH-SY5Y Cells

Oxidative stress is recognized as one of the main reasons for cellular damage and neurodegenerative diseases. Zerumbone is one of the sesquiterpenoid compounds in the essential oil of Zingiber zerumbet Smith. Zerumbone exhibits various physiological activities, such as anticancer, antioxidant, and antibacterial effects. However, studies on the neuroprotective efficacy of zerumbone and the mechanism behind it are lacking. In this study, we explored the neuroprotective efficacy of zerumbone and its mechanism in hydrogen peroxide-treated human neuroblastoma SH-SY5Y cells. H2O2 treatment (400 μM) for 24 h enhanced the generation of intracellular reactive oxygen species (ROS) compared to untreated cells. By contrast, zerumbone treatment significantly suppressed the production of intracellular ROS. Zerumbone significantly inhibited H2O2-induced nitric oxide production and expression of inflammation-related genes. Moreover, zerumbone decreased H2O2-induced mitogen-activated protein kinase (MAPK) protein expression. Various hallmarks of apoptosis in H2O2-treated cells were suppressed in a dose-dependent manner through downregulation of the Bax/Bcl-2 expression ratio by zerumbone. Since activation of AMP-activated kinase (AMPK) is a promising therapeutic target for neurodegenerative diseases, we also investigated the mammalian target of rapamycin (mTOR) as part of the autophagy mechanism in H2O2-treated SH-SY5Y cells. In this study, zerumbone upregulated the expression of Sirtuin 1 (SIRT1) and p-AMPK (which were downregulated by the H2O2 treatment) and downregulated p-mTOR. Altogether, our results propose that inhibition of apoptosis and inflammation by autophagy activation plays an important neuroprotective role in H2O2-treated SH-SY5Y cells. Zerumbone may thus be a potent dietary agent that reduces the onset and progression, as well as prevents neurodegenerative diseases.

BACE1-dependent metabolism of neuregulin 1: Bridging the gap in explaining the occurrence of schizophrenia-like symptoms in Alzheimer's disease with psychosis?

Alzheimer's disease is a neurodegenerative disease mainly characterized by cortico-neuronal atrophy, impaired memory and other cognitive declines. On the other hand, schizophrenia is a neuro-developmental disorder with an overtly active central nervous system pruning system resulting into abrupt connections with common symptoms including disorganised thoughts, hallucination and delusion. Nevertheless, the fronto-temporal anomaly presents itself as a common denominator for the two pathologies. There is even a strong presumption of increased risk of developing co-morbid dementia for schizophrenic individuals and psychosis for Alzheimer's disease patients, overall leading to a further deteriorated quality of life. However, convincing proofs of how these two disorders, although very distant from each other when considering their aetiology, develop coexisting symptoms is yet to be resolved. At the molecular level, the two primarily neuronal proteins β-amyloid precursor protein and neuregulin 1 have been considered in this relevant context, although the conclusions are for the moment only hypotheses. In order to propose a model for explaining the psychotic schizophrenia-like symptoms that sometimes accompany AD-associated dementia, this review projects out on the similar sensitivity shared by these two proteins regarding their metabolism by the β-site APP cleaving enzyme 1.

Molecular and cognitive signatures of ageing partially restored through synthetic delivery of IL2 to the brain

Cognitive decline is a common pathological outcome during aging, with an ill-defined molecular and cellular basis. In recent years, the concept of inflammaging, defined as a low-grade inflammation increasing with age, has emerged. Infiltrating T cells accumulate in the brain with age and may contribute to the amplification of inflammatory cascades and disruptions to the neurogenic niche observed with age. Recently, a small resident population of regulatory T cells has been identified in the brain, and the capacity of IL2-mediated expansion of this population to counter neuroinflammatory disease has been demonstrated. Here, we test a brain-specific IL2 delivery system for the prevention of neurological decline in aging mice. We identify the molecular hallmarks of aging in the brain glial compartments and identify partial restoration of this signature through IL2 treatment. At a behavioral level, brain IL2 delivery prevented the age-induced defect in spatial learning, without improving the general decline in motor skill or arousal. These results identify immune modulation as a potential path to preserving cognitive function for healthy aging.

Boosting neuregulin 1 type-III expression hastens SMA motor axon maturation

Intercellular communication between axons and Schwann cells is critical for attaining the complex morphological steps necessary for axon maturation. In the early onset motor neuron disease spinal muscular atrophy (SMA), many motor axons are not ensheathed by Schwann cells nor grow sufficiently in radial diameter to become myelinated. These developmentally arrested motor axons are dysfunctional and vulnerable to rapid degeneration, limiting efficacy of current SMA therapeutics. We hypothesized that accelerating SMA motor axon maturation would improve their function and reduce disease features. A principle regulator of peripheral axon development is neuregulin 1 type III (NRG1-III). Expressed on axon surfaces, it interacts with Schwann cell receptors to mediate axon ensheathment and myelination. We examined NRG1 mRNA and protein expression levels in human and mouse SMA tissues and observed reduced expression in SMA spinal cord and in ventral, but not dorsal root axons. To determine the impact of neuronal NRG1-III overexpression on SMA motor axon development, we bred NRG1-III overexpressing mice to SMA∆7 mice. Neonatally, elevated NRG1-III expression increased SMA ventral root size as well as axon segregation, diameter, and myelination resulting in improved motor axon conduction velocities. NRG1-III was not able to prevent distal axonal degeneration nor improve axon electrophysiology, motor behavior, or survival of older mice. Together these findings demonstrate that early SMA motor axon developmental impairments can be ameliorated by a molecular strategy independent of SMN replacement providing hope for future SMA combinatorial therapeutic approaches.

The Exosome-Mediated PI3K/Akt/mTOR Signaling Pathway in Neurological Diseases

As major public health concerns associated with a rapidly growing aging population, neurodegenerative diseases (NDDs) and neurological diseases are important causes of disability and mortality. Neurological diseases affect millions of people worldwide. Recent studies have indicated that apoptosis, inflammation, and oxidative stress are the main players of NDDs and have critical roles in neurodegenerative processes. During the aforementioned inflammatory/apoptotic/oxidative stress procedures, the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway plays a crucial role. Considering the functional and structural aspects of the blood-brain barrier, drug delivery to the central nervous system is relatively challenging. Exosomes are nanoscale membrane-bound carriers that can be secreted by cells and carry several cargoes, including proteins, nucleic acids, lipids, and metabolites. Exosomes significantly take part in the intercellular communications due to their specific features including low immunogenicity, flexibility, and great tissue/cell penetration capabilities. Due to their ability to cross the blood-brain barrier, these nano-sized structures have been introduced as proper vehicles for central nervous system drug delivery by multiple studies. In the present systematic review, we highlight the potential therapeutic effects of exosomes in the context of NDDs and neurological diseases by targeting the PI3K/Akt/mTOR signaling pathway.

Rats, Neuregulins and Radical Prostatectomy: A Conceptual Overview

In the contemporary era of early detection, with mostly curative initial treatment for prostate cancer (PC), mortality rates have significantly diminished. In addition, mean age at initial PC diagnosis has decreased. Despite technical advancements, the probability of erectile function (EF) recovery post radical prostatectomy (RP) has not significantly changed throughout the last decade. Due to virtually unavoidable intraoperative cavernous nerve (CN) lesions and operations with younger patients, post-RP erectile dysfunction (ED) has now begun affecting these younger patients. To address this pervasive limitation, a plethora of CN lesion animal model investigations have analyzed the use of systemic/local treatments for EF recovery post-RP. Most promisingly, neuregulins (NRGs) have demonstrated neurotrophic effects in both neurodegenerative disease and peripheral nerve injury models. Recently, glial growth factor 2 (GGF2) has demonstrated far superior, dose-dependent, neuroprotective/restorative effects in the CN injury rat model, as compared to previous therapeutic counterparts. Although potentially impactful, these initial findings remain limited and under-investigated. In an effort to aid clinicians, our paper reviews post-RP ED pathogenesis and currently available therapeutic tools. To stimulate further experimentation, a standardized preparation protocol and in-depth analysis of applications for the CN injury rat model is provided. Lastly, we report on NRGs, such as GGF2, and their potentially revolutionary clinical applications, in hopes of identifying relevant future research directions.

Whole-genome sequencing reveals an association between small genomic deletions and an increased risk of developing Parkinson's disease

Single-nucleotide variants (SNVs) associated with Parkinson's disease (PD) have been investigated mainly through genome-wide association studies. However, other genomic alterations, including copy number variations, remain less explored. In this study, we conducted whole-genome sequencing of primary (310 PD patients and 100 healthy individuals) and independent (100 PD patients and 100 healthy individuals) cohorts from the Korean population to identify high-resolution small genomic deletions, gains, and SNVs. Global small genomic deletions and gains were found to be associated with an increased and decreased risk of PD development, respectively. Thirty significant locus deletions were identified in PD, with most being associated with an increased PD risk in both cohorts. Small genomic deletions in clustered loci located in the GPR27 region had high enhancer signals and showed the closest association with PD. GPR27 was found to be expressed specifically in brain tissue, and GPR27 copy number loss was associated with upregulated SNCA expression and downregulated dopamine neurotransmitter pathways. Clustering of small genomic deletions on chr20 in exon 1 of the GNAS isoform was detected. In addition, we found several PD-associated SNVs, including one in the enhancer region of the TCF7L2 intron, which exhibited a cis-acting regulatory mode and an association with the beta-catenin signaling pathway. These findings provide a global, whole-genome view of PD and suggest that small genomic deletions in regulatory domains contribute to the risk of PD development.

The knowledge domain of cognitive neuroscience of aging: A Scientometric and bibliometric analysis

Cognitive neuroscience of aging (CNA) is a relatively young field compared with other branches of cognitive aging (CA). From the beginning of this century, scholars in CNA have contributed many valuable research to explain the cognitive ability decline in aging brains in terms of functional changes, neuromechanism, and neurodegenerative diseases. However, very few studies have systematically reviewed the research in the domain of CAN, with regard to its primary research topics, theories, findings, and future development. Therefore, this study used CiteSpace to conduct a bibliometric analysis of 1,462 published articles in CNA from Web of Science (WOS) and investigated the highly influential and potential research topics and theories of CNA, as well as important brain areas involved in CAN during 2000-2021. The results revealed that: (1) the research topics of "memory" and "attention" have been the focus of most studies, progressing into a fMRI-oriented stage; (2) the scaffolding theory and hemispheric asymmetry reduction in older adults model hold a key status in CNA, characterizing aging as a dynamic process and presenting compensatory relationships between different brain areas; and (3) age-related changes always occur in temporal (especially the hippocampus), parietal, and frontal lobes and the cognitive declines establish the compensation relationship between the anterior and posterior regions.

PolyAMiner-Bulk: A Machine Learning Based Bioinformatics Algorithm to Infer and Decode Alternative Polyadenylation Dynamics from bulk RNA-seq data

More than half of human genes exercise alternative polyadenylation (APA) and generate mRNA transcripts with varying 3' untranslated regions (UTR). However, current computational approaches for identifying cleavage and polyadenylation sites (C/PASs) and quantifying 3'UTR length changes from bulk RNA-seq data fail to unravel tissue- and disease-specific APA dynamics. Here, we developed a next-generation bioinformatics algorithm and application, PolyAMiner-Bulk, that utilizes an attention-based machine learning architecture and an improved vector projection-based engine to infer differential APA dynamics accurately. When applied to earlier studies, PolyAMiner-Bulk accurately identified more than twice the number of APA changes in an RBM17 knockdown bulk RNA-seq dataset compared to current generation tools. Moreover, on a separate dataset, PolyAMiner-Bulk revealed novel APA dynamics and pathways in scleroderma pathology and identified differential APA in a gene that was identified as being involved in scleroderma pathogenesis in an independent study. Lastly, we used PolyAMiner-Bulk to analyze the RNA-seq data of post-mortem prefrontal cortexes from the ROSMAP data consortium and unraveled novel APA dynamics in Alzheimer's Disease. Our method, PolyAMiner-Bulk, creates a paradigm for future alternative polyadenylation analysis from bulk RNA-seq data.

Promising Molecular Targets in Pharmacological Therapy for Neuronal Damage in Brain Injury

The complex etiopathogenesis of brain injury associated with neurodegeneration has sparked a lot of studies in the last century. These clinical situations are incurable, and the currently available therapies merely act on symptoms or slow down the course of the diseases. Effective methods are being sought with an intent to modify the disease, directly acting on the properly studied targets, as well as to contribute to the development of effective therapeutic strategies, opening the possibility of refocusing on drug development for disease management. In this sense, this review discusses the available evidence for mitochondrial dysfunction induced by Ca2+ miscommunication in neurons, as well as how targeting phosphorylation events may be used to modulate protein phosphatase 2A (PP2A) activity in the treatment of neuronal damage. Ca2+ tends to be the catalyst for mitochondrial dysfunction, contributing to the synaptic deficiency seen in brain injury. Additionally, emerging data have shown that PP2A-activating drugs (PADs) suppress inflammatory responses by inhibiting different signaling pathways, indicating that PADs may be beneficial for the management of neuronal damage. In addition, a few bioactive compounds have also triggered the activation of PP2A-targeted drugs for this treatment, and clinical studies will help in the authentication of these compounds. If the safety profiles of PADs are proven to be satisfactory, there is a case to be made for starting clinical studies in the setting of neurological diseases as quickly as possible.

The neuroprotective effects of oxygen therapy in Alzheimer’s disease: a narrative review

Alzheimer’s disease (AD) is a degenerative neurological disease that primarily affects the elderly. Drug therapy is the main strategy for AD treatment, but current treatments suffer from poor efficacy and a number of side effects. Non-drug therapy is attracting more attention and may be a better strategy for treatment of AD. Hypoxia is one of the important factors that contribute to the pathogenesis of AD. Multiple cellular processes synergistically promote hypoxia, including aging, hypertension, diabetes, hypoxia/obstructive sleep apnea, obesity, and traumatic brain injury. Increasing evidence has shown that hypoxia may affect multiple pathological aspects of AD, such as amyloid-beta metabolism, tau phosphorylation, autophagy, neuroinflammation, oxidative stress, endoplasmic reticulum stress, and mitochondrial and synaptic dysfunction. Treatments targeting hypoxia may delay or mitigate the progression of AD. Numerous studies have shown that oxygen therapy could improve the risk factors and clinical symptoms of AD. Increasing evidence also suggests that oxygen therapy may improve many pathological aspects of AD including amyloid-beta metabolism, tau phosphorylation, neuroinflammation, neuronal apoptosis, oxidative stress, neurotrophic factors, mitochondrial function, cerebral blood volume, and protein synthesis. In this review, we summarized the effects of oxygen therapy on AD pathogenesis and the mechanisms underlying these alterations. We expect that this review can benefit future clinical applications and therapy strategies on oxygen therapy for AD.

Neurotrophic Factors and Dendritic Spines

Dendritic spines are highly dynamic structures that play important roles in neuronal plasticity. The morphologies and the numbers of dendritic spines are highly variable, and this diversity is correlated with the different morphological and physiological features of this neuronal compartment. Dendritic spines can change their morphology and number rapidly, allowing them to adapt to plastic changes. Neurotrophic factors play important roles in the brain during development. However, these factors are also necessary for a variety of processes in the postnatal brain. Neurotrophic factors, especially members of the neurotrophin family and the ephrin family, are involved in the modulation of long-lasting effects induced by neuronal plasticity by acting on dendritic spines, either directly or indirectly. Thereby, the neurotrophic factors play important roles in processes attributed, for example, to learning and memory.

Neurodegenerative disease and antioxidant biomarkers: A bidirectional Mendelian randomization study

Objective

Previous observational studies have suggested that antioxidant imbalance is correlated with neurodegenerative diseases, while its cause-effect remains unclear. Thus, the goal of the present study is to explore the causal relationship between 11 antioxidant biomarkers and 3 most common neurodegenerative diseases [Alzheimer's disease (AD), Amyotrophic Lateral Sclerosis (ALS) and Parkinson's disease (PD)].

Methods

A bidirectional Mendelian randomization (MR) study was performed to investigate the causal effects by using 3 main methods (Variance Weighted (IVW), Weighted Median (WM), and MR-Egger regression) in the European population. The data of 11 antioxidant biomarkers were obtained from the open database by the most up-to-date Genome-Wide Association Studies (GWAS), the summary statistics of PD and ALS were obtained from the International Parkinson's Disease Genomics Consortium (IPDGC) (33,674 cases, and 449,056 controls), and the International Amyotrophic Lateral Sclerosis Genomics Consortium (IALSC) (20,806 cases and 59,804 controls), respectively. For AD, we specifically used two recently published GWAS data, one from the International Genomics of Alzheimer's Project (IGAP) (21,982 cases and 41,944 controls), and the other from a large meta-analysis (71,880 cases and 383,378 controls) as validation data.

Results

Based on the Bonferroni correction p < 0.0015, there was no significant causal evidence for the antioxidant biomarkers on neurodegenerative diseases, however, the reverse analysis found that AD was significantly related to the decrease in retinol (IVW: beta = -0.023, p = 0.0007; WM: beta = -0.025, p = 0.0121), while the same analysis was carried out between the AD validation database and retinol, the results were consistent (IVW: beta = -0.064, p = 0.025). Moreover, AD on Glutathione S-transferase (GST), PD on Glutathione Peroxidase (GPX) as well as PD on uric acid (UA) also indicated potential causal-and-effect associations (IVW: p = 0.025; p = 0.027; p = 0.021, respectively).

Conclusions

There was no sufficient evidence that antioxidant imbalance has a significant causal effect on neurodegenerative diseases. However, this study revealed that genetically predicted AD was significantly related to the decrease in retinol, which provides a new insight into previous research and indicates the possibility to regard retinol as potential biomarker for the diagnosis and progress of AD.

Implicative role of epidermal growth factor receptor and its associated signaling partners in the pathogenesis of Alzheimer's disease

Epidermal growth factor receptor (EGFR) plays a pivotal role in early brain development, although its expression pattern declines in accordance with the maturation of the active nervous system. However, recurrence of EGFR expression in brain cells takes place during neural functioning decline and brain atrophy in order to maintain the homeostatic neuronal pool. As a consequence, neurotoxic lesions such as amyloid beta fragment (Aβ_1-42) formed during the alternative splicing of amyloid precursor protein in Alzheimer's disease (AD) elevate the expression of EGFR. This inappropriate peptide deposition on EGFR results in the sustained phosphorylation of the downstream signaling axis, leading to extensive Aβ_1-42 production and tau phosphorylation as subsequent pathogenesis. Recent reports convey that the pathophysiology of AD is correlated with EGFR and its associated membrane receptor complex molecules. One such family of molecules is the annexin superfamily, which has synergistic relationships with EGFR and is known for membrane-bound signaling that contributes to a variety of inflammatory responses. Besides, Galectin-3, tissue-type activated plasminogen activator, and many more, which lineate the secretion of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-18) result in severe neuronal loss. Altogether, we emphasized the perspectives of cellular senescence up-regulated by EGFR and its associated membrane receptor molecules in the pathogenesis of AD as a target for a therapeutical alternative to intervene in AD.

Brain organoid-on-a-chip: A next-generation human brain avatar for recapitulating human brain physiology and pathology

Neurodegenerative diseases and neurodevelopmental disorders have become increasingly prevalent; however, the development of new pharmaceuticals to treat these diseases has lagged. Animal models have been extensively utilized to identify underlying mechanisms and to validate drug efficacies, but they possess inherent limitations including genetic heterogeneity with humans. To overcome these limitations, human cell-based in vitro brain models including brain-on-a-chip and brain organoids have been developed. Each technique has distinct advantages and disadvantages in terms of the mimicry of structure and microenvironment, but each technique could not fully mimic the structure and functional aspects of the brain tissue. Recently, a brain organoid-on-a-chip (BOoC) platform has emerged, which merges brain-on-a-chip and brain organoids. BOoC can potentially reflect the detailed structure of the brain tissue, vascular structure, and circulation of fluid. Hence, we summarize recent advances in BOoC as a human brain avatar and discuss future perspectives. BOoC platform can pave the way for mechanistic studies and the development of pharmaceuticals to treat brain diseases in future.

The Crosstalk between HepG2 and HMC-III Cells: In Vitro Modulation of Gene Expression with Conditioned Media

Epidemiological studies have postulated an inverse correlation between developing cancer and neurodegeneration. It is known that the secretome plays a vital role in cell-cell communication in health and disease; the microglia is the resident macrophage of the central nervous system which maintains neuronal integrity by adapting as the microenvironment changes. The present study aimed to identify, in a cell model, biomarkers that link neurodegenerative diseases to cancer or vice versa. Real-time PCR and western blot analysis were used to characterize the effects on gene and protein expression of human hepatoblastoma (HepG2) and human microglia (HMC-III) cells after exchanging part of their conditioned medium. Biomarkers of the endoplasmic reticulum, and mitophagy and inflammatory processes were evaluated. In both cell types, we observed the activation of cytoprotective mechanisms against any potential pro-oxidant or pro-inflammatory signals present in secretomes. In contrast, HepG2 but not HMC-III cells seem to trigger autophagic processes following treatment with conditioned medium of microglia, thus suggesting a cell-specific adaptive response.

Expression and Biological Functions of miRNAs in Chronic Pain: A Review on Human Studies

Chronic pain is a major public health problem and an economic burden worldwide. However, its underlying pathological mechanisms remain unclear. MicroRNAs (miRNAs) are a class of small noncoding RNAs that post-transcriptionally regulate gene expression and serve key roles in physiological and pathological processes. This review aims to synthesize the human studies examining miRNA expression in the pathogenesis of chronic primary pain and chronic secondary pain. Additionally, to understand the potential pathophysiological impact of miRNAs in these conditions, an in silico analysis was performed to reveal the target genes and pathways involved in primary and secondary pain and their differential regulation in the different types of chronic pain. The findings, methodological issues and challenges of miRNA research in the pathophysiology of chronic pain are discussed. The available evidence suggests the potential role of miRNA in disease pathogenesis and possibly the pain process, eventually enabling this role to be exploited for pain monitoring and management.

Mechanisms Underlying the Interaction Between Chronic Neurological Disorders and Microbial Metabolites via Tea Polyphenols Therapeutics

The number of hydroxyl groups and existence of characteristic structural groups in tea polyphenols (TP) make them have antioxidant activity, which gives TP anti-inflammatory effects, toward protecting the intestinal flora and brain neurons. Host-associated microbial metabolites are emerging as dominant modifiers of the central nervous system. As yet, the investigations on host-microbiota crosstalking remain challenging, studies focusing on metabolites such as serotonin, short-chain fatty acids, and others have pinpointed multiple actionable signaling pathways relevant to host health. However, there are still complexities and apparent limitations inherent in transforming complex human diseases to corresponding animal models. Here, we choose to discuss several intestinal metabolites with research value, as crucial areas for assessing TP-mediated chronic brain diseases interactions with microbial.

The Role of EREG/EGFR Pathway in Tumor Progression

Aberrant activation of the epidermal growth factor receptor (EGFR/ERBB1) by erythroblastic leukemia viral oncogene homolog (ERBB) ligands contributes to various tumor malignancies, including lung cancer and colorectal cancer (CRC). Epiregulin (EREG) is one of the EGFR ligands and is low expressed in most normal tissues. Elevated EREG in various cancers mainly activates EGFR signaling pathways and promotes cancer progression. Notably, a higher EREG expression level in CRC with wild-type Kirsten rat sarcoma viral oncogene homolog (KRAS) is related to better efficacy of therapeutic treatment. By contrast, the resistance of anti-EGFR therapy in CRC was driven by low EREG expression, aberrant genetic mutation and signal pathway alterations. Additionally, EREG overexpression in non-small cell lung cancer (NSCLC) is anticipated to be a therapeutic target for EGFR-tyrosine kinase inhibitor (EGFR-TKI). However, recent findings indicate that EREG derived from macrophages promotes NSCLC cell resistance to EGFR-TKI treatment. The emerging events of EREG-mediated tumor promotion signals are generated by autocrine and paracrine loops that arise from tumor epithelial cells, fibroblasts, and macrophages in the tumor microenvironment (TME). The TME is a crucial element for the development of various cancer types and drug resistance. The regulation of EREG/EGFR pathways depends on distinct oncogenic driver mutations and cell contexts that allows specific pharmacological targeting alone or combinational treatment for tailored therapy. Novel strategies targeting EREG/EGFR, tumor-associated macrophages, and alternative activation oncoproteins are under development or undergoing clinical trials. In this review, we summarize the clinical outcomes of EREG expression and the interaction of this ligand in the TME. The EREG/EGFR pathway may be a potential target and may be combined with other driver mutation targets to combat specific cancers.