The Ubiquitin-Proteasome System: Potential Therapeutic Targets for Alzheimer's Disease and Spinal Cord Injury

Role of BAG5 in Protein Quality Control: Double-Edged Sword?

Cardiovascular disorder is the major health burden and cause of death among individuals worldwide. As the cardiomyocytes lack the ability for self-renewal, it is utmost necessary to surveil the protein quality in the cells. The Bcl-2 associated anthanogene protein (BAG) family and molecular chaperones (HSP70, HSP90) actively participate in maintaining cellular protein quality control (PQC) to limit cellular dysfunction in the cells. The BAG family contains a unique BAG domain which facilitates their interaction with the ATPase domain of the heat shock protein 70 (HSP70) to assist in protein folding. Among the BAG family members (BAG1-6), BAG5 protein is unique since it has five domains in tandem, and the binding of BD5 induces certain conformational changes in the nucleotide-binding domain (NBD) of HSP70 such that it loses its affinity for binding to ADP and results in enhanced protein refolding activity of HSP70. In this review, we shall describe the role of BAG5 in modulating mitophagy, endoplasmic stress, and cellular viability. Also, we have highlighted the interaction of BAG5 with other proteins, including PINK, DJ-1, CHIP, and their role in cellular PQC. Apart from this, we have described the role of BAG5 in cellular metabolism and aging.

Evaluation of Styrylbenzene analog- FSB and its affinity to bind parenchymal plaques and tangles in patients of Alzheimer's disease

Although several histochemical markers for senile plaques (SP) and neurofibrillary tangles (NFTs) have been synthesized since the discovery of plaques in Alzheimer's disease (AD), only a handful of these markers stain both lesions in the human brain. Despite discovery of its ability to stain both SP and NFT over 13 years ago, the styrylbenzene derivative, (E,E)-1-fluoro-2,5-bis-(3-hydroxycarbonyl-4-hydroxy)styrylbenzene (FSB), has only recently gained attention, primarily due to its ability to function as a contrasting agent for MRI imaging of AD pathology in vivo. The structure of the compound is a nuclide with quantized angular momentum, which explains its value as a contrast agent. In the current study, modification of the established staining procedure produced meaningful improvement in the labeling of plaques and tangles in the human brain. We utilized two rodent models of AD to show FSB's value in labeling both Aβ and tau lesions. Furthermore, our current modification allows us to detect SP in rodent brains in 15 min and both SP and NFT in human brains within 20 min. The study presents new evidence regarding potential binding targets for FSB as well as optimization protocols in which various parameters have been manipulated to show how section thickness, use of frozen versus paraffin-embedded sections, and selection of staining media can affect the intensity of the plaque and tangle staining in the brain. To determine the target FSB potentially binds, we performed double immunolabeling of FSB with mOC64 (a conformational antibody that label Aβ_1-42). Results indicated that all plaques in the brain colocalized with mOC64, suggesting that FSB has the potential to bind all Aβ containing plaques, making it a very sensitive detector of multiple forms of SP... All antibodies were assessed for the degree of colocalization with FSB in order to better understand potential binding targets. We found more than 90% hyperphosphorylated Tau against AT8, AT180 and S214 colocalized with FSB labeled tangles. On the other hand, more than 90% of the mOC64 containing plaques colocalized with FSB stained plaques. Our results indicate that FSB is a valuable marker that can be used to detect AD pathologies in human and rodent brains with greater fluorescence intensity relative to other conventional fluorescence markers.

UCHL1 and Proteasome in Blood Serum in Relation to Dietary Habits, Concentration of Selected Antioxidant Minerals and Total Antioxidant Status among Patients with Alzheimer's Disease

Alzheimer's disease (AD) is an incurable neurodegenerative disease. It is the most common form of dementia among the elderly population. So far, no effective methods of its treatment have been found. Research to better understand the mechanism of pathology may provide new methods for early diagnosis. This, in turn, could enable early intervention that could slow or halt disease progression and improve patients' quality of life. Therefore, minimally invasive markers, including serum-based markers, are being sought to improve the diagnosis of AD. One of the important markers may be the concentration of UCHL1 and the proteasome in the blood serum. Their concentration can be affected by many factors, including eating habits. This study was conducted in 110 patients with early or moderate AD, with a mean age of 78.0 ± 8.1 years. The patients were under the care of the Podlasie Center of Psychogeriatrics and the Department of Neurology (Medical University of Białystok, Poland). The control group consisted of 60 healthy volunteers, matched for gender and age. The concentration of UCHL1 and the 20S proteasome subunit were measured by surface plasmon resonance imaging (SPRI). In addition, a nutritional interview was conducted with patients with AD, which assessed the frequency of consumption of 36 groups of products. In the group of patients with AD, compared to the control group, we showed a significantly higher concentration of UCHL1 (56.05 vs. 7.98 ng/mL) and the proteasome (13.02 vs. 5.72 µg/mL). Moreover, we found a low negative correlation between UCHL1 and the proteasome in the control group, and positive in the AD group. The analysis of eating habits showed that the consumption of selected groups of products may affect the concentration of the tested components, and therefore may have a protective effect on AD.

USP14: Structure, Function, and Target Inhibition

Ubiquitin-specific protease 14 (USP14), a deubiquitinating enzyme (DUB), is associated with proteasomes and exerts a dual function in regulating protein degradation. USP14 protects protein substrates from degradation by removing ubiquitin chains from proteasome-bound substrates, whereas promotes protein degradation by activating the proteasome. Increasing evidence have shown that USP14 is involved in several canonical signaling pathways, correlating with cancer, neurodegenerative diseases, autophagy, immune responses, and viral infections. The activity of USP14 is tightly regulated to ensure its function in various cellular processes. Structural studies have demonstrated that free USP14 exists in an autoinhibited state with two surface loops, BL1 and BL2, partially hovering above and blocking the active site cleft binding to the C-terminus of ubiquitin. Hence, both proteasome-bound and phosphorylated forms of USP14 require the induction of conformational changes in the BL2 loop to activate its deubiquitinating function. Due to its intriguing roles in the stabilization of disease-causing proteins and oncology targets, USP14 has garnered widespread interest as a therapeutic target. In recent years, significant progress has been made on identifying inhibitors targeting USP14, despite the complexity and challenges in improving their selectivity and affinity for USP14. In particular, the crystal structures of USP14 complexed with IU1-series inhibitors revealed the underlying allosteric regulatory mechanism and enabled the further design of potent inhibitors. In this review, we summarize the current knowledge regarding the structure, regulation, pathophysiological function, and selective inhibition of USP14, including disease associations and inhibitor development.

UCH-L3 structure and function: Insights about a promising drug target

In the past few years, researchers have shed light on the immense importance of ubiquitin in numerous regulatory pathways. The post-translational addition of mono or poly-ubiquitin molecules namely "ubiquitinoylation" is therefore pivotal to maintain the cell's vitality, maturation, differentiation, and division. Part of conserving homeostasis stems from maintaining the ubiquitin pool in the vicinity of the cell's intracellular environment; this crucial role is played by deubiquitylating enzymes (DUBs) that cleave ubiquitin molecules from target molecules. To date, they are categorized into 7 families with ubiquitin carboxyl c-terminal de-hydrolase family (UCH) as the most common and well-studied. Ubiquitin C-terminal hydrolase L (UCH-L3) is a significant protein in this family as it has been implicated in many molecular and cellular processes with its mRNA identified in a range of body tissues including the brain. It goes without saying that it manifests in maintaining health and when abnormally regulated in disease. As it is an attractive small molecule drug target, scientists have used high throughput screening (HTS) and other drug discovery methods to discover inhibitors for this enzyme for the treatment of cancer and neurodegenerative diseases. In this review we present an overview of UCH-L3 catalytic mechanism, structure, its role in DNA repair and cancer along with the inhibitors discovered so far to halt its activity.

Roles and Mechanisms of the Protein Quality Control System in Alzheimer's Disease

Alzheimer's disease (AD) is characterized by the deposition of senile plaques (SPs) and the formation of neurofibrillary tangles (NTFs), as well as neuronal dysfunctions in the brain, but in fact, patients have shown a sustained disease progression for at least 10 to 15 years before these pathologic biomarkers can be detected. Consequently, as the most common chronic neurological disease in the elderly, the challenge of AD treatment is that it is short of effective biomarkers for early diagnosis. The protein quality control system is a collection of cellular pathways that can recognize damaged proteins and thereby modulate their turnover. Abundant evidence indicates that the accumulation of abnormal proteins in AD is closely related to the dysfunction of the protein quality control system. In particular, it is the synthesis, degradation, and removal of essential biological components that have already changed in the early stage of AD, which further encourages us to pay more attention to the protein quality control system. The review mainly focuses on the endoplasmic reticulum system (ERS), autophagy-lysosome system (ALS) and the ubiquitin-proteasome system (UPS), and deeply discusses the relationship between the protein quality control system and the abnormal proteins of AD, which can not only help us to understand how and why the complex regulatory system becomes malfunctional during AD progression, but also provide more novel therapeutic strategies to prevent the development of AD.

Exploration of Aberrant E3 Ligases Implicated in Alzheimer's Disease and Development of Chemical Tools to Modulate Their Function

The Ubiquitin Proteasome System (UPS) is responsible for the degradation of misfolded or aggregated proteins via a multistep ATP-dependent proteolytic mechanism. This process involves a cascade of ubiquitin (Ub) transfer steps from E1 to E2 to E3 ligase. The E3 ligase transfers Ub to a targeted protein that is brought to the proteasome for degradation. The inability of the UPS to remove misfolded or aggregated proteins due to UPS dysfunction is commonly observed in neurodegenerative diseases, such as Alzheimer's disease (AD). UPS dysfunction in AD drives disease pathology and is associated with the common hallmarks such as amyloid-β (Aβ) accumulation and tau hyperphosphorylation, among others. E3 ligases are key members of the UPS machinery and dysfunction or changes in their expression can propagate other aberrant processes that accelerate AD pathology. The upregulation or downregulation of expression or activity of E3 ligases responsible for these processes results in changes in protein levels of E3 ligase substrates, many of which represent key proteins that propagate AD. A powerful way to better characterize UPS dysfunction in AD and the role of individual E3 ligases is via the use of high-quality chemical tools that bind and modulate specific E3 ligases. Furthermore, through combining gene editing with recent advances in 3D cell culture, in vitro modeling of AD in a dish has become more relevant and possible. These cell-based models of AD allow for study of specific pathways and mechanisms as well as characterization of the role E3 ligases play in driving AD. In this review, we outline the key mechanisms of UPS dysregulation linked to E3 ligases in AD and highlight the currently available chemical modulators. We present several key approaches for E3 ligase ligand discovery being employed with respect to distinct classes of E3 ligases. Where possible, specific examples of the use of cultured neurons to delineate E3 ligase biology have been captured. Finally, utilizing the available ligands for E3 ligases in the design of proteolysis targeting chimeras (PROTACs) to degrade aberrant proteins is a novel strategy for AD, and we explore the prospects of PROTACs as AD therapeutics.

Mutation of a Ubiquitin Carboxy Terminal Hydrolase L1 Lipid Binding Site Alleviates Cell Death, Axonal Injury, and Behavioral Deficits After Traumatic Brain Injury in Mice

Ubiquitin carboxy terminal hydrolase L1 (UCHL1) is a protein highly expressed in neurons that may play important roles in the ubiquitin proteasome pathway (UPP) in neurons, axonal integrity, and motor function after traumatic brain injury (TBI). Binding of reactive lipid species to cysteine 152 of UCHL1 results in unfolding, aggregation, and inactivation of the enzyme. To test the role of this mechanism in TBI, mice bearing a cysteine to alanine mutation at site 152 (C152A mice) that renders UCHL1 resistant to inactivation by reactive lipids were subjected to the controlled cortical impact model (CCI) of TBI and compared to wild type (WT) controls. Alterations in protein ubiquitination and activation of autophagy pathway markers in traumatized brain were detected by immunoblotting. Cell death and axonal injury were determined by histological assessment and anti-amyloid precursor protein (APP) immunohistochemistry. Behavioral outcomes were determined using the beam balance and Morris water maze tests. C152A mice had reduced accumulation of ubiquitinated proteins, decreased activation of the autophagy markers Beclin-1 and LC3B, a decreased number of abnormal axons, decreased CA1 cell death, and improved motor and cognitive function compared to WT controls after CCI; no significant change in spared tissue volume was observed. These results suggest that binding of lipid substrates to cysteine 152 of UCHL1 is important in the pathogenesis of injury and recovery after TBI and may be a novel target for future therapeutic approaches.

Diet and redox state in maintaining skeletal muscle health and performance at high altitude

High altitude exposure leads to compromised physical performance with considerable weight loss. The major stressor at high altitude is hypobaric hypoxia which leads to disturbance in redox homeostasis. Oxidative stress is a well-known trigger for many high altitude illnesses and regulates several key signaling pathways under stressful conditions. Altered redox homeostasis is considered the prime culprit of high altitude linked skeletal muscle atrophy. Hypobaric hypoxia disturbs redox homeostasis through increased RONS production and compromised antioxidant system. Increased RONS disturbs the cellular homeostasis via multiple ways such as inflammation generation, altered protein anabolic pathways, redox remodeling of RyR1 that contributed to dysregulated calcium homeostasis, enhanced protein degradation pathways via activation calcium-regulated protein, calpain, and apoptosis. Ultimately, all the cellular signaling pathways aggregately result in skeletal muscle atrophy. Dietary supplementation of phytochemicals could become a safe and effective intervention to ameliorate skeletal muscle atrophy and enhance the physical performance of the personnel who are staying at high altitude regions. The present evidence-based review explores few dietary supplementations which regulate several signaling mechanisms and ameliorate hypobaric hypoxia induced muscle atrophy and enhances physical performance. However, a clinical research trial is required to establish proof-of-concept.

EFhd2 brain interactome reveals its association with different cellular and molecular processes

EFhd2 is a conserved calcium-binding protein that is highly expressed in the central nervous system. We have shown that EFhd2 interacts with tau protein, a key pathological hallmark in Alzheimer's disease and related dementias. However, EFhd2's physiological and pathological functions in the brain are still poorly understood. To gain insights into its physiological function, we identified proteins that co-immunoprecipitated with EFhd2 from mouse forebrain and hindbrain, using tandem mass spectrometry (MS). In addition, quantitative mass spectrometry was used to detect protein abundance changes due to the deletion of the Efhd2 gene in mouse forebrain and hindbrain regions. Our data show that mouse EFhd2 is associated with cytoskeleton components, vesicle trafficking modulators, cellular stress response-regulating proteins, and metabolic proteins. Moreover, proteins associated with the cytoskeleton, vesicular transport, calcium signaling, stress response, and metabolic pathways showed differential abundance in Efhd2^(-/-) mice. This study presents, for the first time, an EFhd2 brain interactome that it is associated with different cellular and molecular processes. These findings will help prioritize further studies to investigate the mechanisms by which EFhd2 modulates these processes in physiological and pathological conditions of the nervous system.

Regulation of topoisomerase II stability and activity by ubiquitination and SUMOylation: clinical implications for cancer chemotherapy

DNA topoisomerases II (TOP2) are peculiar enzymes (TOP2α and TOP2β) that modulate the conformation of DNA by momentarily breaking double-stranded DNA to allow another strand to pass through, and then rejoins the DNA phosphodiester backbone. TOP2α and TOP2β play vital roles in nearly all events involving DNA metabolism, including DNA transcription, replication, repair, and chromatin remodeling. Beyond these vital functions, TOP2 enzymes are therapeutic targets for various anticancer drugs, termed TOP2 poisons, such as teniposide, etoposide, and doxorubicin. These drugs exert their antitumor activity by inhibiting the activity of TOP2-DNA cleavage complexes (TOP2ccs) containing DNA double-strand breaks (DSBs), subsequently leading to the degradation of TOP2 by the 26S proteasome, thereby exposing the DSBs and eliciting a DNA damage response. Failure of the DSBs to be appropriately repaired leads to genomic instability. Due to this mechanism, patients treated with TOP2-based drugs have a high incidence of secondary malignancies and cardiotoxicity. While the cytotoxicity associated with TOP2 poisons appears to be TOP2α-dependent, the DNA sequence rearrangements and formation of DSBs appear to be mediated primarily through TOP2β inhibition, likely due to the differential degradation patterns of TOP2α and TOP2β. Research over the past few decades has shown that under various conditions, the ubiquitin-proteasome system (UPS) and the SUMOylation pathway are primarily responsible for regulating the stability and activity of TOP2 and are therefore critical regulators of the therapeutic effect of TOP2-targeting drugs. In this review, we summarize the current progress on the regulation of TOP2α and TOP2β by ubiquitination and SUMOylation. By fully elucidating the basic biology of these essential and complex molecular mechanisms, better strategies may be developed to improve the therapeutic efficacy of TOP2 poisons and minimize the risks of therapy-related secondary malignancy.

Immunotherapeutics for AD: A Work in Progress

Alzheimer's Disease (AD), often called the 'Plague of the 21st Century,' is a progressive, irreversible neurodegenerative disorder that leads to the degeneration and death of neurons. Multiple factors, such as genetic defects, epigenetic regulations, environmental factors, or cerebrovascular damage, are a manifestation of the neurodegenerative process that begins to occur decades before the onset of disease. To date, no treatment or therapeutic strategy has proven to be potent in inhibiting its progress or reversing the effects of the disease. The ever-increasing numbers and lack of sufficient therapies that can control or reverse the effects of the disease have propelled research in the direction of devising efficient therapeutic strategies for AD. This review comprehensively discusses the active and passive immunotherapies against Amyloid-β and Tau protein, which remain the popular choice of targets for AD therapeutics. Some of the prospective immunotherapies against Aβ plaques have failed due to various reasons. Much of the research is focused on targeting Tau, specifically, targeting the mid-region of extracellular Tau due to their potential to prevent seeding and hence the spread of neurofibrillary tangles (NFTs). Thus, there is a need to thoroughly understand the disease onset mechanisms and discover effective therapeutic strategies.

Overview of piperlongumine analogues and their therapeutic potential

Natural products have long been an important source for discovery of new drugs to treat human diseases. Piperlongumine (PL) is an amide alkaloid isolated from Piper longum L. (long piper) and other piper plants and has received widespread attention because of its diverse biological activities. A large number of PL derivatives have been designed, synthesized and assessed in many pharmacological functions, including antiplatelet aggregation, neuroprotective activities, anti-diabetic activities, anti-inflammatory activities, anti-senolytic activities, immune activities, and antitumor activities. Among them, the anti-tumor effects and application of PL and its derivatives are most extensively studied. We herein summarize the development of PL derivatives, the structure and activity relationships (SARs), and their therapeutic potential on the treatments of various diseases, especially against cancer. We also discussed the challenges and future directions associated with PL and its derivatives in these indications.

Effects of deubiquitylases on the biological behaviors of neural stem cells

New neurons are generated throughout life in distinct regions of the mammalian brain due to the proliferation and differentiation of neural stem cells (NSCs). Ubiquitin, a post-translational modification of cellular proteins, is an important factor in regulating neurogenesis. Deubiquitination is a biochemical process that mediates the removal of ubiquitin moieties from ubiquitin-conjugated substrates. Recent studies have provided growing evidence that deubiquitylases (DUBs) which reverse ubiquitylation process play critical roles in NSCs maintenance, differentiation and maturation. This review mainly focused on the relationship of DUBs and NSCs, and further summarized recent advances in our understanding of DUBs on regulating NSCs biological behaviors.

Synaptopathy Mechanisms in ALS Caused by C9orf72 Repeat Expansion

Amyotrophic Lateral Sclerosis (ALS) is a complex neurodegenerative disease caused by degeneration of motor neurons (MNs). ALS pathogenic features include accumulation of misfolded proteins, glutamate excitotoxicity, mitochondrial dysfunction at distal axon terminals, and neuronal cytoskeleton changes. Synergies between loss of C9orf72 functions and gain of function by toxic effects of repeat expansions also contribute to C9orf72-mediated pathogenesis. However, the impact of haploinsufficiency of C9orf72 on neurons and in synaptic functions requires further examination. As the motor neurons degenerate, the disease symptoms will lead to neurotransmission deficiencies in the brain, spinal cord, and neuromuscular junction. Altered neuronal excitability, synaptic morphological changes, and C9orf72 protein and DPR localization at the synapses, suggest a potential involvement of C9orf72 at synapses. In this review article, we provide a conceptual framework for assessing the putative involvement of C9orf72 as a synaptopathy, and we explore the underlying and common disease mechanisms with other neurodegenerative diseases. Finally, we reflect on the major challenges of understanding C9orf72-ALS as a synaptopathy focusing on integrating mitochondrial and neuronal cytoskeleton degeneration as biomarkers and potential targets to treat ALS neurodegeneration.

The role of tumor necrosis factor-α and interferon-γ in the hyperglycemia-induced ubiquitination and loss of platelet endothelial cell adhesion molecule-1 in rat retinal endothelial cells

OBJECTIVE

This study aimed to investigate the role of the hyperglycemia-induced increase in tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in the ubiquitination and degradation of platelet endothelial cell adhesion molecule-1 (PECAM-1) in the diabetic retina.

METHODS

Type I diabetes was induced in rats by the injection of streptozotocin, with age-matched non-diabetic rats as controls. Primary rat retinal microvascular endothelial cells were grown in normal or high glucose media for 6 days or in normal glucose media for 24 h with addition of TNF-α and/or IFN-γ. PECAM-1, TNF-α, IFN-γ, and ubiquitin levels were assessed using Western blotting, immunofluorescence, and immunoprecipitation assays. Additionally, proteasome activity was assessed both in vivo and in vitro.

RESULTS

Under hyperglycemic conditions, total ubiquitination levels in the retina and RRMECs, and PECAM-1 ubiquitination levels in RRMECs, were significantly increased. Additionally, TNF-α and IFN-γ levels were significantly increased under hyperglycemic conditions. PECAM-1 levels in RRMECs treated with TNF-α and/or IFN-γ were significantly decreased. Moreover, there was a significant decrease in proteasome activity in the diabetic retina, hyperglycemic RRMECs, and RRMECs treated with TNF-α or IFN-γ.

CONCLUSION

Tumor necrosis factor-α and IFN-γ may contribute to the hyperglycemia-induced loss of PECAM-1 in retinal endothelial cells, possibly by upregulating PECAM-1 ubiquitination.

The autocrine regulation of insulin-like growth factor-1 in human brain of Alzheimer's disease

BACKGROUND

Insulin-like growth factor (IGF) binding protein (IGFBP)-3 and cyclic Glycine-Proline (cGP) regulate circulating IGF-1 function that is associated with cognition. The association between IGF-1 function and Alzheimer's disease (AD) remains inconclusive. This study evaluated the changes of IGFBPs and cGP, and their effects on the bioavailability and function of IGF-1 in human brain of AD cases.

METHODS

Using biological and mathematic analysis we measured the concentrations of total, bound and unbound forms of IGF-1, IGFBPs and cGP in the inferior-frontal gyrus and middle-frontal gyrus of human AD (n = 15) and control cases (n = 15). The association between the changes of total concentration of these peptides and total protein concentration in brain tissues were also analyzed.

RESULTS

The unbound bioavailable IGF-1 was lower whereas the bound cGP and IGFBP-3 were higher in AD than the control cases. Total protein that was lower in AD than control cases, was negatively associated with cGP concentration of control cases and with IGFBP-3 concentration of AD cases.

CONCLUSIONS

The results provide direct evidence for IGF-1 deficiency in AD brain due to lower bioavailable IGF-1. The increase of bound IGFBP-3 impaired autocrine regulation. The increase of bound cGP is an autocrine response to improve the bioavailability and function of IGF-1 in AD brain.

AVAILABILITY OF DATA AND MATERIAL

All data generated or analysed during this study are included in this published article. Additional datasets analysed during the current study available from the corresponding author on reasonable request.

A Biomarker for Concussion: The Good, the Bad, and the Unknown

BACKGROUND

Traumatic brain injury (TBI) is a significant cause of morbidity, mortality, and disability in the US, with >2.8 million patients presenting to the emergency department (ED) annually. However, the diagnosis of TBI is challenging and presents a number of difficulties, particularly at the mildest end of the spectrum: concussion. A number of groups have researched biomarkers to aid in the evaluation of TBI, and most recently in 2018 the Food and Drug Administration approved a new blood-based immunoassay biomarker using ubiquitin carboxyl hydrolase L1 and glial fibrillary acidic protein to aid in head computed tomography (CT) triage.

CONTENT

This review clarifies the practical challenges in assessing and implementing a new blood biomarker. It then examines the clinical context and need, as well as the evidence used to validate this new immunoassay.

SUMMARY

Concussion is a multifaceted diagnosis with a need for biomarkers to assist in diagnostic and prognostic assessment. Recent articles in the lay press have revealed misunderstanding about the function of this new test, expressing hopes that this biomarker serves patients at the mildest end of the spectrum and is useful for athletes and children. None of these assumptions are correct, as this biomarker has been evaluated in patients only at the moderate end of the spectrum and has been validated only in adults presenting to the ED who have already been triaged to receive head CT, not in athletes or children. The next steps for this assay should consider clinical work flow and clarifying its intended use, including integration with existing triage methods, and validating the assay for a broader population.

Molecular Mechanisms Underlying TDP-43 Pathology in Cellular and Animal Models of ALS and FTLD

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are neurodegenerative disorders that exist on a disease spectrum due to pathological, clinical and genetic overlap. In up to 97% of ALS cases and ~50% of FTLD cases, the primary pathological protein observed in affected tissues is TDP-43, which is hyperphosphorylated, ubiquitinated and cleaved. The TDP-43 is observed in aggregates that are abnormally located in the cytoplasm. The pathogenicity of TDP-43 cytoplasmic aggregates may be linked with both a loss of nuclear function and a gain of toxic functions. The cellular processes involved in ALS and FTLD disease pathogenesis include changes to RNA splicing, abnormal stress granules, mitochondrial dysfunction, impairments to axonal transport and autophagy, abnormal neuromuscular junctions, endoplasmic reticulum stress and the subsequent induction of the unfolded protein response. Here, we review and discuss the evidence for alterations to these processes that have been reported in cellular and animal models of TDP-43 proteinopathy.

Is PROTAC technology really a game changer for central nervous system drug discovery?

Introduction: Central nervous system (CNS) diseases affect a large portion of the population, however, few therapeutic options are available. Furthermore, to date, clinical trials have been largely unsuccessful due to difficulty in targeting the undruggable, toxic proteins that underly many CNS disorders. PROteolysis Targeting Chimeras (PROTACs) are a rapidly emerging technology that has been proposed as a potential treatment option for various CNS diseases by hijacking the endogenous protein degradation process.Areas Covered: Herein, the authors discuss how the application of PROTACs may be beneficial in the treatment of major CNS diseases. They further discuss the main advantages and disadvantages of using PROTACs in the CNS, focusing on potential limitations such as their transient nature, localization, blood-brain barrier permeability and proteasome dysfunction.Expert opinion: It is evident that PROTACs have significant potential as a therapeutic tool for the treatment of CNS diseases and there is preliminary evidence suggesting that PROTACs could be successful in a clinical setting. Nevertheless, numerous limitations exist that must be overcome before this technology can be applied as a successful therapeutic for CNS disorders. Importantly, more in vivo studies are needed to determine the feasibility and effectiveness of using PROTACs in the brain.

Anatomical and neurochemical organization of the serotonergic system in the mammalian brain and in particular the involvement of the dorsal raphe nucleus in relation to neurological diseases

The brainstem is a neglected brain area in neurodegenerative diseases, including Alzheimer's and Parkinson's disease, frontotemporal lobar degeneration and autonomic dysfunction. In Depression, several observations have been made in relation to changes in one particular the Dorsal Raphe Nucleus (DRN) which also points toward as key area in various age-related and neurodevelopmental diseases. The DRN is further thought to be related to stress regulated processes and cognitive events. It is involved in neurodegeneration, e.g., amyloid plaques, neurofibrillary tangles, and impaired synaptic transmission in Alzheimer's disease as shown in our autopsy findings. The DRN is a phylogenetically old brain area, with projections that reach out to a large number of regions and nuclei of the central nervous system, particularly in the forebrain. These ascending projections contain multiple neurotransmitters. One of the main reasons for the past and current interest in the DRN is its involvement in depression, and its main transmitter serotonin. The DRN also points toward the increased importance and focus of the brainstem as key area in various age-related and neurodevelopmental diseases. This review describes the morphology, ascending projections and the complex neurotransmitter nature of the DRN, stressing its role as a key research target into the neural bases of depression.

Optimization and Anti-Cancer Properties of Fluoromethylketones as Covalent Inhibitors for Ubiquitin C-Terminal Hydrolase L1

The deubiquitinating enzyme (DUB) UCHL1 is implicated in various disease states including neurodegenerative disease and cancer. However, there is a lack of quality probe molecules to gain a better understanding on UCHL1 biology. To this end a study was carried out to fully characterize and optimize the irreversible covalent UCHL1 inhibitor VAEFMK. Structure-activity relationship studies identified modifications to improve activity versus the target and a full cellular characterization was carried out for the first time with this scaffold. The studies produced a new inhibitor, 34, with an IC50 value of 7.7 µM against UCHL1 and no observable activity versus the closest related DUB UCHL3. The molecule was also capable of selectively inhibiting UCHL1 in cells and did not demonstrate any discernible off-target toxicity. Finally, the molecule was used for initial probe studies to assess the role of UCHL1 role in proliferation of myeloma cells and migration behavior in small cell lung cancer cells making 34 a new tool to be used in the biological evaluation of UCHL1.

Neurodegenerative Pathways in Alzheimer's Disease: A Review

Alzheimer's disease (AD) is a complex neurodegenerative disease that leads to insidious deterioration of brain functions and is considered the sixth leading cause of death in the world. Alzheimer's patients suffer from memory loss, cognitive deficit and behavioral changes; thus, they eventually follow a low-quality life. AD is considered as a multifactorial disorder involving different neuropathological mechanisms. Recent research has identified more than 20 pathological factors that are promoting disease progression. Three significant hypotheses are said to be the root cause of disease pathology, which include acetylcholine deficit, the formation of amyloid-beta senile plaques and tau protein hyperphosphorylation. Apart from these crucial factors, pathological factors such as apolipoprotein E (APOE), glycogen synthase kinase 3β, notch signaling pathway, Wnt signaling pathway, etc., are considered to play a role in the advancement of AD and therefore could be used as targets for drug discovery and development. As of today, there is no complete cure or effective disease altering therapies for AD. The current therapy is assuring only symptomatic relief from the disease, and progressive loss of efficacy for these symptomatic treatments warrants the discovery of newer drugs by exploring these novel drug targets. A comprehensive understanding of these therapeutic targets and their neuropathological role in AD is necessary to identify novel molecules for the treatment of AD rationally.

The Effects of Capsaicin on Gastrointestinal Cancers

Gastrointestinal (GI) cancers are a group of diseases with very high positions in the ranking of cancer incidence and mortality. While they show common features regarding the molecular mechanisms involved in cancer development, organ-specific pathophysiological processes may trigger distinct signaling pathways and intricate interactions with inflammatory cells from the tumoral milieu and mediators involved in tumorigenesis. The treatment of GI cancers is a topic of increasing interest due to the severity of these diseases, their impact on the patients' survivability and quality of life, and the burden they set on the healthcare system. As the efficiency of existing drugs is hindered by chemoresistance and adverse reactions when administered in high doses, new therapies are sought, and emerging drugs, formulations, and substance synergies are the focus of a growing number of studies. A class of chemicals with great potential through anti-inflammatory, anti-oxidant, and anti-tumoral effects is phytochemicals, and capsaicin in particular is the subject of intensive research looking to validate its position in complementing cancer treatment. Our paper thoroughly reviews the available scientific evidence concerning the effects of capsaicin on major GI cancers and its interactions with the molecular pathways involved in the course of these diseases.

Escape from X chromosome inactivation and female bias of autoimmune diseases

Generally, autoimmune diseases are more prevalent in females than males. Various predisposing factors, including female sex hormones, X chromosome genes, and the microbiome have been implicated in the female bias of autoimmune diseases. During embryogenesis, one of the X chromosomes in the females is transcriptionally inactivated, in a process called X chromosome inactivation (XCI). This equalizes the impact of two X chromosomes in the females. However, some genes escape from XCI, providing a basis for the dual expression dosage of the given gene in the females. In the present review, the contribution of the escape genes to the female bias of autoimmune diseases will be discussed.

EphA4 regulates Aβ production via BACE1 expression in neurons

Several lines of evidence suggest that the aggregation and deposition of amyloid-β peptide (Aβ) initiate the pathology of Alzheimer's disease (AD). Recently, a genome-wide association study demonstrated that a single-nucleotide polymorphism proximal to the EPHA4 gene, which encodes a receptor tyrosine kinase, is associated with AD risk. However, the molecular mechanism of EphA4 in the pathogenesis of AD, particularly in Aβ production, remains unknown. Here, we performed several pharmacological and biological experiments both in vitro and in vivo and demonstrated that EphA4 is responsible for the regulation of Aβ production. Pharmacological inhibition of EphA4 signaling and knockdown of Epha4 led to increased Aβ levels accompanied by increased expression of β-site APP cleaving enzyme 1 (BACE1), which is an enzyme responsible for Aβ production. Moreover, EPHA4 overexpression and activation of EphA4 signaling via ephrin ligands decreased Aβ levels. In particular, the sterile-alpha motif domain of EphA4 was necessary for the regulation of Aβ production. Finally, EPHA4 mRNA levels were significantly reduced in the brains of AD patients, and negatively correlated with BACE1 mRNA levels. Our results indicate a novel mechanism of Aβ regulation by EphA4, which is involved in AD pathogenesis.

Identifying the Mechanisms and Molecular Targets of Yizhiqingxin Formula on Alzheimer's Disease: Coupling Network Pharmacology with GEO Database

Background

Yizhiqingxin formula (YZQX) is a promising formula for the treatment of Alzheimer’s disease (AD) with significant clinical effects. Here, we coupled a network pharmacology approach with the Gene Expression Omnibus (GEO) database to illustrate comprehensive mechanisms and screen for molecular targets of YZQX for AD treatment.

Methods

First, active ingredients of YZQX were screened for the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database with the absorption, distribution, metabolism, and excretion (ADME) parameters. Subsequently, putative targets of active ingredients were predicted using the DrugBank database. AD-related targets were retrieved by analyzing published microarray data (accession number GSE5281). Protein–protein interaction (PPI) networks of YZQX putative targets and AD-related targets were constructed visually and merged to identify candidate targets for YZQX against AD using Cytoscape 3.7.2 software. We performed gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis to further clarify the biological functions of the candidate targets. The gene-pathway network was established to filter for key target genes.

Results

Forty-three active ingredients were identified, and 193 putative target genes were predicted. Seven hundred and ten targets related to AD were screened with |log2 FC| > 1 and P < 0.05. Based on the PPI network, 110 target genes of YZQX against AD were identified. Moreover, 32 related pathways including the PI3K-Akt signaling pathway, MAPK signaling pathway, ubiquitin-mediated proteolysis, apoptosis and the NF-kappa B signaling pathway were significantly enriched. In the gene-pathway network, MAPK1, AKT1, TP53, MDM2, EGFR, RELA, SRC, GRB2, CUL1, and MYC targets are putative core genes for YZQX in AD treatment.

Conclusion

YZQX against AD may exert its neuroprotective effect via the PI3K-Akt signaling pathway, MAPK signaling pathway, and ubiquitin-mediated proteolysis. YZQX may be a promising drug that can be used in the treatment of AD.

Thermal cycling protects SH-SY5Y cells against hydrogen peroxide and β-amyloid-induced cell injury through stress response mechanisms involving Akt pathway

Neurodegenerative diseases (NDDs) are becoming a major threat to public health, according to the World Health Organization (WHO). The most common form of NDDs is Alzheimer’s disease (AD), boasting 60–70% share. Although some debates still exist, excessive aggregation of β-amyloid protein (Aβ) and neurofibrillary tangles has been deemed one of the major causes for the pathogenesis of AD. A growing number of evidences from studies, however, have suggested that reactive oxygen species (ROS) also play a key role in the onset and progression of AD. Although scientists have had some understanding of the pathogenesis of AD, the disease still cannot be cured, with existing treatment only capable of providing a temporary relief at best, partly due to the obstacle of blood-brain barrier (BBB). The study was aimed to ascertain the neuroprotective effect of thermal cycle hyperthermia (TC-HT) against hydrogen peroxide (H₂O₂) and Aβ-induced cytotoxicity in SH-SY5Y cells. Treating cells with this physical stimulation beforehand significantly improved the cell viability and decreased the ROS content. The underlying mechanisms may be due to the activation of Akt pathway and the downstream antioxidant and prosurvival proteins. The findings manifest significant potential of TC-HT in neuroprotection, via inhibition of oxidative stress and cell apoptosis. It is believed that coupled with the use of drugs or natural compounds, this methodology can be even more effective in treating NDDs.

The small molecule PSSM0332 disassociates the CRL4ADCAF8 E3 ligase complex to decrease the ubiquitination of NcoR1 and inhibit the inflammatory response in a mouse sepsis-induced myocardial dysfunction model

Sepsis-induced myocardial dysfunction (SIMD) is a life-threatening complication caused by inflammation, but how it is initiated is still unclear. Several studies have shown that extracellular high mobility group box 1 (HMGB1), an important cytokine triggering inflammation, is overexpressed during the pathogenesis of SIMD, but the underlying mechanism regarding its overexpression is still unknown. Herein, we discovered that CUL4A (cullin 4A) assembled an E3 ligase complex with RBX1 (ring-box 1), DDB1 (DNA damage-binding protein 1), and DCAF8 (DDB1 and CUL4 associated factor 8), termed CRL4A^DCAF8, which ubiquitinated and degraded NcoR1 (nuclear receptor corepressor 1) in an LPS-induced SIMD mouse model. The degradation of NcoR1 failed to form a complex with the SP1 transcription factor, leading to the upregulation of HMGB1. Mature HMGB1 functioned as an effector to induce the expression of proinflammatory cytokines, causing inflammation and resulting in SIMD pathology. Using an in vitro AlphaScreen technology, we identified three small molecules that could inhibit the CUL4A-RBX1 interaction. Of them, PSSM0332 showed the strongest ability to inhibit the ubiquitination of NcoR1, and its administration in SIMD mice exhibited promising effects on decreasing the inflammatory response. Collectively, our results reveal that the CRL4A^DCAF8 E3 ligase is critical for the initiation of SIMD by regulating the expression of HMGB1 and proinflammatory cytokines. Our results suggest that PSSM0332 is a promising candidate to inhibit the inflammatory response in the pathogenesis of SIMD, which will provide a new option for the therapy of SIMD.

Transcriptomic sex differences in sensory neuronal populations of mice

Many chronic pain conditions show sex differences in their epidemiology. This could be attributed to sex-dependent differential expression of genes (DEGs) involved in nociceptive pathways, including sensory neurons. This study aimed to identify sex-dependent DEGs in estrous female versus male sensory neurons, which were prepared by using different approaches and ganglion types. RNA-seq on non-purified sensory neuronal preparations, such as whole dorsal root ganglion (DRG) and hindpaw tissues, revealed only a few sex-dependent DEGs. Sensory neuron purification increased numbers of sex-dependent DEGs. These DEG sets were substantially influenced by preparation approaches and ganglion types [DRG vs trigeminal ganglia (TG)]. Percoll-gradient enriched DRG and TG neuronal fractions produced distinct sex-dependent DEG groups. We next isolated a subset of sensory neurons by sorting DRG neurons back-labeled from paw and thigh muscle. These neurons have a unique sex-dependent DEG set, yet there is similarity in biological processes linked to these different groups of sex-dependent DEGs. Female-predominant DEGs in sensory neurons relate to inflammatory, synaptic transmission and extracellular matrix reorganization processes that could exacerbate neuro-inflammation severity, especially in TG. Male-selective DEGs were linked to oxidative phosphorylation and protein/molecule metabolism and production. Our findings catalog preparation-dependent sex differences in neuronal gene expressions in sensory ganglia.

Alignment of Alzheimer's Disease Amyloid-β Peptide and Herpes Simplex Virus-1 pUL15 C-Terminal Nuclease Domain

Background:

The cause of Alzheimer’s disease (AD) is poorly understood. Neurotropic microbes, particularly herpesviruses, might set off chronic neuroinflammation. Amyloid-β (Aβ) has antimicrobial properties and could represent a brain defense against infection.

Objective:

We searched for protein sequence alignment between herpes simplex virus type I (HSV-1) HSV-2, and Aβ.

Methods:

Protein data bank (pdb) structures for Aβ, HSV-1, and HSV-2 were searched on the RCSB Protein Data Bank. The protein structures were superimposed and aligned on PYMOL v 2.3.4.

Results:

For HSV-1 and Aβ, amino acid residues ser549 – his569 of HSV-1 aligned closely with residues asp7 - asn27 of Aβ. For HSV-2 and Aβ, amino acid residues of HSV-2 aligned less closely than those of HSV-1 with residues of Aβ.

Conclusion:

Conjugating and binding to the same alpha helix in the HSV-1 protease, Aβ could be marking HSV-1 for attack by the immune system, providing a rapid inherited immune response to a destructive neurotropic virus that would otherwise require the more time-consuming involvement of T-cells, B-cells, and the adaptive immune system. But older people do not respond to viral infections as well as younger individuals. When HSV-1 infection advances in an old person, more and more amyloid is produced, forming an adhesive web. As the brain tries to hold the pathologic process in check, neuroinflammation increases and spreads. Progressive neurodegeneration and cognitive decline are the outcome.

Cerebrospinal fluid levels of GFAP and pNF-H are elevated in patients with chronic spinal cord injury and neurological deterioration

BACKGROUND

Years after a traumatic spinal cord injury (SCI), a subset of patients may develop progressive clinical deterioration due to intradural scar formation and spinal cord tethering, with or without an associated syringomyelia. Meningitis, intradural hemorrhages, or intradural tumor surgery may also trigger glial scar formation and spinal cord tethering, leading to neurological worsening. Surgery is the treatment of choice in these chronic SCI patients.

OBJECTIVE

We hypothesized that cerebrospinal fluid (CSF) and plasma biomarkers could track ongoing neuronal loss and scar formation in patients with spinal cord tethering and are associated with clinical symptoms.

METHODS

We prospectively enrolled 12 patients with spinal cord tethering and measured glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase L1 (UCH-L1), and phosphorylated Neurofilament-heavy (pNF-H) in CSF and blood. Seven patients with benign lumbar intradural tumors and 7 patients with cervical radiculopathy without spinal cord involvement served as controls.

RESULTS

All evaluated biomarker levels were markedly higher in CSF than in plasma, without any correlation between the two compartments. When compared with radiculopathy controls, CSF GFAP and pNF-H levels were higher in patients with spinal cord tethering (p ≤ 0.05). In contrast, CSF UCH-L1 levels were not altered in chronic SCI patients when compared with either control groups.

CONCLUSIONS

The present findings suggest that in patients with spinal cord tethering, CSF GFAP and pNF-H levels might reflect ongoing scar formation and neuronal injury potentially responsible for progressive neurological deterioration.

Regulation of organic anion transporters: Role in physiology, pathophysiology, and drug elimination

The members of the organic anion transporter (OAT) family are mainly expressed in kidney, liver, placenta, intestine, and brain. These transporters play important roles in the disposition of clinical drugs, pesticides, signaling molecules, heavy metal conjugates, components of phytomedicines, and toxins, and therefore critical for maintaining systemic homeostasis. Alterations in the expression and function of OATs contribute to the intra- and inter-individual variability of the therapeutic efficacy and the toxicity of many drugs, and to many pathophysiological conditions. Consequently, the activity of these transporters must be highly regulated to carry out their normal functions. This review will present an update on the recent advance in understanding the cellular and molecular mechanisms underlying the regulation of renal OATs, emphasizing on the post-translational modification (PTM), the crosstalk among these PTMs, and the remote sensing and signaling network of OATs. Such knowledge will provide significant insights into the roles of these transporters in health and disease.

The essential role of osteoclast-derived exosomes in magnetic nanoparticle-infiltrated hydroxyapatite scaffold modulated osteoblast proliferation in an osteoporosis model

Magnetic hydroxyapatite (MHA) scaffolds promoted osteoblast proliferation in a model of osteoporosis through altering the osteoclast-derived exosomal cargo and decreasing the efficiency of exosome uptake by osteoblasts. Noticeably, certain proteins including ubiquitin, ATP and reactive oxygen species decreased in the osteoclast-derived exosomal cargo with MHA stimulation, while Rho kinase increased.

Selection and Validation of Reference Genes for the qRT-PCR Assays of Populus ussuriensis Gene Expression under Abiotic Stresses and Related ABA Treatment

Populus ussuriensis Kom. is one of the most important tree species for forest renewal in the eastern mountainous areas of Northeast China due to its fast growth, high yield, and significant commercial and ecological value. The selection of optimal reference genes for the normalization of qRT-PCR data is essential for the analysis of relative gene expression. In this study, fourteen genes were selected and assessed for their expression stability during abiotic stress (drought, high salinity, and cold stress) and after the treatment with the drought-related hormone ABA. Three algorithms were used, geNorm, NormFinder, and BestKeeper, and a comprehensive ranking of candidate reference genes was produced based on their output. The most appropriate reference genes were UBQ10 and RPL24 for drought and ABA treatment, UBQ10 and TUB3 for cold stress, and UBQ10 and 60S rRNA for high salinity. Overall, UBQ10 was the most stable reference gene for use as an internal control, whereas PP2A was the least stable. The expression of two target genes (P5CS2 and GI) was used to further verify that the selected reference genes were suitable for gene expression normalization. This work comprehensively assesses the stability of reference genes in Populus ussuriensis and identifies suitable reference genes for normalization during qRT-PCR analysis.

Protein Degradome of Spinal Cord Injury: Biomarkers and Potential Therapeutic Targets

Degradomics is a proteomics sub-discipline whose goal is to identify and characterize protease-substrate repertoires. With the aim of deciphering and characterizing key signature breakdown products, degradomics emerged to define encryptic biomarker neoproteins specific to certain disease processes. Remarkable improvements in structural and analytical experimental methodologies as evident in research investigating cellular behavior in neuroscience and cancer have allowed the identification of specific degradomes, increasing our knowledge about proteases and their regulators and substrates along with their implications in health and disease. A physiologic balance between protein synthesis and degradation is sought with the activation of proteolytic enzymes such as calpains, caspases, cathepsins, and matrix metalloproteinases. Proteolysis is essential for development, growth, and regeneration; however, inappropriate and uncontrolled activation of the proteolytic system renders the diseased tissue susceptible to further neurotoxic processes. In this article, we aim to review the protease-substrate repertoires as well as emerging therapeutic interventions in spinal cord injury at the degradomic level. Several protease substrates and their breakdown products, essential for the neuronal structural integrity and functional capacity, have been characterized in neurotrauma including cytoskeletal proteins, neuronal extracellular matrix glycoproteins, cell junction proteins, and ion channels. Therefore, targeting exaggerated protease activity provides a potentially effective therapeutic approach in the management of protease-mediated neurotoxicity in reducing the extent of damage secondary to spinal cord injury.

Ubiquitin carboxy-terminal hydrolase L1 - physiology and pathology

Ubiquitin C-terminal hydrolase 1 (UCHL1) is an enzyme unique for its multiple activity - both ligase and hydrolase. UCHL1 was first identified as an abundant protein found in the brain and testes, however its expression is not limited to the neuronal compartment. UCHL1 is also highly expressed in carcinomas of various tissue origins, including those from brain, lung, breast, kidney, colon, prostate, pancreas and mesenchymal tissues. Loss-of-function studies and an inhibitor for UCHL1 confirmed the importance of UCHL1 for cancer therapy. So far biological significance of UCHL1 was described in the following processes: spermatogenesis, oncogenesis, angiogenesis, cell proliferation and differentiation in skeletal muscle, inflammation, tissue injury, neuronal injury and neurodegeneration.

A Systematic Bioinformatics Workflow With Meta-Analytics Identified Potential Pathogenic Factors of Alzheimer's Disease

Potential pathogenic factors, other than well-known APP, APOE4, and PSEN, can be further identified from transcriptomics studies of differentially expressed genes (DEGs) that are specific for Alzheimer’s disease (AD), but findings are often inconsistent or even contradictory. Evidence corroboration by combining meta-analysis and bioinformatics methods may help to resolve existing inconsistencies and contradictions. This study aimed to demonstrate a systematic workflow for evidence synthesis of transcriptomic studies using both meta-analysis and bioinformatics methods to identify potential pathogenic factors. Transcriptomic data were assessed from GEO and ArrayExpress after systematic searches. The DEGs and their dysregulation states from both DNA microarray and RNA sequencing datasets were analyzed and corroborated by meta-analysis. Statistically significant DEGs were used for enrichment analysis based on KEGG and protein–protein interaction network (PPIN) analysis based on STRING. AD-specific modules were further determined by the DIAMOnD algorithm, which identifies significant connectivity patterns between specific disease-associated proteins and non-specific proteins. Within AD-specific modules, the nodes of highest degrees (>95th percentile) were considered as potential pathogenic factors. After systematic searches of 225 datasets, extensive meta-analyses among 25 datasets (21 DNA microarray datasets and 4 RNA sequencing datasets) identified 9,298 DEGs. The dysregulated genes and pathways in AD were associated with impaired amyloid-β (Aβ) clearance. From the AD-specific module, Fyn, and EGFR were the most statistically significant and biologically relevant. This meta-analytical study suggested that the reduced Aβ clearance in AD pathogenesis was associated with the genes encoding Fyn and EGFR, which were key receptors in Aβ downstream signaling.

Ubiquitin C-Terminal Hydrolase L1: Biochemical and Cellular Characterization of a Covalent Cyanopyrrolidine-Based Inhibitor

The deubiquitinase (DUB) ubiquitin C-terminal hydrolase L1 (UCHL1) is expressed primarily in the central nervous system under normal physiological conditions. However, UCHL1 is overexpressed in various aggressive forms of cancer with strong evidence supporting UCHL1 as an oncogene in lung, glioma, and blood cancers. In particular, the level of UCHL1 expression in these cancers correlates with increased invasiveness and metastatic behavior, as well as poor patient prognosis. Although UCHL1 is considered an oncogene with potential as a therapeutic target, there remains a significant lack of useful small-molecule probes to pharmacologically validate in vivo targeting of the enzyme. Herein, we describe the characterization of a new covalent cyanopyrrolidine-based UCHL1 inhibitory scaffold in biochemical and cellular studies to better understand the utility of this inhibitor in elucidating the role of UCHL1 in cancer biology.

Perturbations of Ubiquitin-Proteasome-Mediated Proteolysis in Aging and Alzheimer's Disease

The ubiquitin-proteasome pathway (UPP) has multiple roles in the normal nervous system, including the development of synaptic connections and synaptic plasticity. Research over the past several years has indicated a role for the UPP in aging without any overt pathology in the brain. In addition, malfunction of the UPP is implicated in Alzheimer’s disease (AD) and dementia associated with it. In this mini review article, we assess the literature on the role of protein degradation by the UPP in aging and in AD with special emphasis on dysregulation of the UPP and its contribution to cognitive decline and impairment.

Current and emerging therapeutic targets of alzheimer's disease for the design of multi-target directed ligands

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease, and a major cause of death worldwide. The number of people suffering from this debilitating disorder is rising at an unprecedented rate, with a subsequent surge in healthcare costs. Only four drugs are clinically available for the treatment of AD symptoms, but they are not disease-modifying. Consequently, there is an urgent need for a cure. Although the cause of this debilitating condition remains poorly understood, it is believed that several factors may be involved in combination - including, health and lifestyle, environmental, and genetic factors. In recent years, a number of hallmarks of the disease have also been discovered, and it is believed that these factors may play an important role in the development of AD. Amyloid aggregation is one such factor which has been highly investigated, in addition to cholinesterase enzymes and tau aggregation. In the last decade, multi-target drugs have been increasingly investigated for their application to AD treatment. By combining two or more pharmacophores in a single compound, it is possible to synthesise a drug which can target several factors that are involved in AD development. This is a particularly attractive approach as it would avoid the use of combination therapies. As a result, it could reduce the burden on carers and families, and decrease healthcare and social care costs. Many active pharmacophores have been employed for the development of hybrid drugs, due to their abilities to inhibit the factors currently widely recognised to be involved in AD. These compounds have demonstrated promising results; however, research is still required to optimise the pharmacological profiles of the drugs, in addition to their potencies. Meanwhile, extensive research is continuously being performed into other potential targets for the treatment of AD. Based on the results obtained thus far, it is likely that multi-target compounds will continue to be increasingly studied in the future as potential treatments for AD.

Endo-lysosomal pathway and ubiquitin-proteasome system dysfunction in Alzheimer's disease pathogenesis

Several lines of evidence have shown that defects in the endo-lysosomal autophagy degradation pathway and the ubiquitin-proteasome system play a role in Alzheimer's Disease (AD) pathogenesis and pathophysiology. Early pathological changes, such as marked enlargement of endosomal compartments, gradual accumulation of autophagic vacuoles (AVs) and lysosome dyshomeostasis, are well-recognized in AD. In addition to these pathological indicators, many genetic variants of key regulators in the endo-lysosomal autophagy networks and the ubiquitin-proteasome system have been found to be associated with AD. Furthermore, altered expression levels of key proteins in these pathways have been found in AD human brain tissues, primary cells and AD mouse models. In this review, we discuss potential disease mechanisms underlying the dysregulation of protein homeostasis governing systems. While the importance of two major protein degradation pathways in AD pathogenesis has been highlighted, targeted therapy at key components of these pathways has great potential in developing novel therapeutic interventions for AD. Future investigations are needed to define molecular mechanisms by which these complex regulatory systems become malfunctional at specific stages of AD development and progression, which will facilitate future development of novel therapeutic interventions. It is also critical to investigate all key components of the protein degradation pathways, both upstream and downstream, to improve our abilities to manipulate transport pathways with higher efficacy and less side effects.

Effect of M2 macrophage adoptive transfer on transcriptome profile of injured spinal cords in rats

The previous studies showed that alternatively activated anti-inflammatory macrophage (M2) adoptive immunity can improve the proportion of local M2 cells and play the neuroprotective effect after spinal cord injury (SCI). Its molecular mechanism is not yet very clear. Therefore, this study aims to analyze the effect of the M2 adoptive transfer on the local expression of gene transcription. Sprague-Dawley (SD) rats were used for culture of macrophages and establishment of SCI models. After SCI, the polarized M2 macrophages were transferred to the injured rats by tail vein injection. Seven days after operation, the differentially expressed genes (DEGs) in the spinal cords were analyzed by RNA-sequencing (RNA-Seq). Then, the functional enrichment analysis and pathways were performed by using gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), respectively. RNA-Seq showed that M2 adoptive immunity can down-regulate many well-studied gene expressions associated with signaling pathways of inflammatory, such as antigen processing and presentation, phagosome, cell adhesion molecules, natural killer cell-mediated cytotoxicity, endocytosis, proteasome, and Toll-like receptor signaling pathway. These may explain the mechanism of our previous adoptive immunization of M2 cells to provide neuroprotection for SCI. In addition, a novel pathway, retinoic acid-inducible gene-1 (RIG-I)-like receptor signaling pathway was found to be involved in the pathological process of SCI and the response to M2 adoptive immunity as well. This will provide a new explanation for the pathological mechanism of SCI and a new theoretical and experimental basis for its clinical treatment. The raw Illumina data are available at http://www.ncbi.nlm.nih.gov/sra (accession number PRJNA517238).

Impact statement

This research aimed to analyze the effect of M2 macrophage adoptive transfer on the local expression of gene transcription after SCI by RNA-Seq. The results showed that M2 adoptive immunity can down-regulate many well-studied gene expressions associated with signaling pathways of inflammatory. These may explain the mechanism of our previous adoptive immunization of M2 cells to provide neuroprotection for SCI. In addition, a novel pathway, RIG-I-like receptor signaling pathway was also found to involve in the pathological process of SCI and the response to M2 adoptive immunity. This will provide a new explanation for the pathological mechanism of SCI and a new theoretical and experimental basis for its clinical treatment.