Secreted Amyloid Precursor Protein-Alpha Promotes Arc Protein Synthesis in Hippocampal Neurons

Prenatal Exposure To Valproic Acid Induces Increased Autism-Like Behaviors and Impairment of Learning and Memory Functions in Rat Offspring by Upregulating ADAM10 Expression

Autism spectrum disorder (ASD) involves a complex neurodevelopmental pathogenesis. A disintegrin and metalloproteinase 10 (ADAM10) plays a crucial role in embryonic brain development and neural network stability. This study aimed to investigate the influence of ADAM10 on excitation/inhibition (E/I) balance, autism-like behaviors, and learning and memory dysfunction in rats prenatally exposed to valproic acid (VPA) and determine potential intervention strategies. The VPA-exposed group exhibited increased levels of ADAM10 and secreted amyloid precursor protein-α (sAPPα). Moreover, overexpression of glutamate decarboxylase 1 and N-methyl-D-aspartate receptors was observed. High-performance liquid chromatography-mass spectrometry revealed elevated levels of glutamate, glutamine, and γ-aminobutyric acid, as well as an E/I imbalance in the VPA group. Additionally, narrower synaptic clefts as well as increased postsynaptic density and synaptic vesicles were observed. Remarkably, intraperitoneal administration of ADAM10 inhibitor during the critical period of synaptic development significantly improved ASD-like behavior and learning and memory function in VPA-exposed rats. This intervention effectively reduced abnormally high sAPPα levels in the prefrontal cortex and corrected abnormal E/I balance. Thus, inhibiting ADAM10 overexpression may improve the E/I imbalance, alleviate core symptoms of ASD, and improve learning and memory dysfunction. The use of ADAM10 inhibitor represents a potential therapeutic strategy for treating ASD patients with intellectual disabilities.

Restoring Brain Pathways Involved in Diabetes-Associated Neurocognitive Disorders: The Potential of Dipeptidyl Peptidase 4 Inhibitors as a Therapeutic Strategy

BACKGROUND

Diabetes, a widespread chronic metabolic disease, is projected to affect 783 million people globally by 2045. Recent studies emphasize the neuroprotective potential of dipeptidyl peptidase 4 (DPP4i) inhibitors, pointing toward a promising avenue for intervention in addressing cognitive challenges associated with diabetes. Due to limited data on the effect of DPP4i on brain pathways involvedin diabetes-related neurocognitive disorders, the decision was made to conduct this study to fill existing knowledge gaps on this topic.

METHODS

The primary aim of our study was to evaluate the potential of DPP4 inhibitors (DPP4i) in preventing cognitive decline in mice with type 2 diabetes (T2D), placing special emphasis on gaining insight into the complex molecular mechanisms underlying this action.

RESULTS

We examined drug efficacy in modulating neurotrophic factors, calcium levels, and the expression of key genes (HIF1α, APP, Arc) crucial for neural plasticity. Conducting cognitive assessments with the hole board and passive avoidance tests, we discerned a remarkable influence of shortterm gliptin usage on the limiting progress of cognitive dysfunction in diabetic mice. The administration of DPP4 inhibitors ledto heightened neurotrophin levels, increased HIF1α in the prefrontal cortex, and a significant elevation in Arc mRNA levels.

CONCLUSION

Our findings reveal that DPP4 inhibitors effectively limit the progression of diabetesrelated cognitive disorders. This breakthrough discovery not only opens new research avenues but also constitutes a potential starting point for creating innovative strategies for the treatment of central nervous system disorders focused on improving cognitive abilities.

Alpha-secretase inhibition impairs Group I metabotropic glutamate receptor-mediated protein synthesis, long-term potentiation and long-term depression

Group I metabotropic glutamate receptors (Gp1-mGluRs) exert a host of effects on cellular functions, including enhancement of protein synthesis and the associated facilitation of long-term potentiation (LTP) and induction of long-term depression (LTD). However, the complete cascades of events mediating these events are not fully understood. Gp1-mGluRs trigger α-secretase cleavage of amyloid precursor protein, producing soluble amyloid precursor protein-α (sAPPα), a known regulator of LTP. However, the α-cleavage of APP has not previously been linked to Gp1-mGluR's actions. Using rat hippocampal slices, we found that the α-secretase inhibitor tumour necrosis factor-alpha protease inhibitor-1, which inhibits both disintegrin and metalloprotease 10 (ADAM10) and 17 (ADAM17) activity, blocked or reduced the ability of the Gp1-mGluR agonist (R,S)-3,5-dihydroxyphenylglycine (DHPG) to stimulate protein synthesis, metaplastically prime future LTP and elicit sub-maximal LTD. In contrast, the specific ADAM10 antagonist GI254023X did not affect the regulation of plasticity, suggesting that ADAM17 but not ADAM10 is involved in mediating these effects of DHPG. However, neither drug affected LTD that was strongly induced by either high-concentration DHPG or paired-pulse synaptic stimulation. Our data suggest that moderate Gp1-mGluR activation triggers α-secretase sheddase activity targeting APP or other membrane-bound proteins as part of a more complex signalling cascade than previously envisioned. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.

Network pharmacology-based analysis of Jin-Si-Wei on the treatment of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Jin-Si-Wei (JSW), a traditional Chinese medicine (TCM) formula, have cognitive enhancing effect and delay the memory decline in an animal model of AD， which has been reported. However, the therapeutic mechanism of JSW in the treatment of AD remains unclear.

AIM OF THE STUDY

This study aimed to verify the pharmacodynamics of JSW in the treatment of AD, and to explore its potential mechanism based on network pharmacology, molecular docking and experimental validation both in vitro and in vivo.

MATERIALS AND METHODS

In this study, the underlying mechanism of JSW against AD was investigated by the integration of network pharmacology. Then, the core pathways and biological process of JSW were verified by experiment, including behavioral test and pathological and biochemical assays with 6-month-old APPswe/PS1ΔE9 transgenic (APP/PS1) mice in vivo and verified with Aβ1-42-stimulated SH-SY5Y cells in vitro. At last, molecular docking was used to show the binding activity of each active ingredient to the core genes of JSW treatment in AD.

RESULTS

A Drug-Ingredient-Target network was established, which included 363 ingredients and 116 targets related to the JSW treatment of AD. The main metabolic pathway of JSW treatment for AD is neuroactive ligand-receptor interaction pathway, and biological processes are mainly involved in Aβ metabolic process. In vivo experiments, compared with APP/PS1 mice, the cognitive and memory ability of mice was significantly improved after JSW administration. In brain tissue of APP/PS1 mice, JSW could increase the contents of low-density lipoprotein receptor-related protein 1 (LRP-1), enkephalinase (NEP) and Acetyl choline (ACh), and decrease the contents of Aβ1-42, amyloid precursor protein (APP) and receptor for advanced glycation end products (RAGE), decrease the vitality of cholinesterase (AChE) and choline acetyltransferase (ChAT). Besides, JSW could increase α-secretase expression and decrease β/γ-secretase expression, and improve the number and morphology of synapses in CA1 region of the hippocampus of APP/PS1 mice. In vitro experiments, Drug-Containing Serum (JSW-serum) has a neuroprotective effect by reducing the apoptosis on Aβ1-42-stimulated SH-SY5Y cells. Molecular docking results showed that 2-Isopropyl-8-methylphenanthrene-3,4-dione had strong binding activity with PTGS2, which maybe a potential ingredient for the treatment of AD.

CONCLUSIONS

JSW improves AD in APP/PS1 mice, and this therapeutic effect may be achieved in part by altering the neuroactive ligand-receptor interaction pathway.

Advances and Challenges in Gene Therapy for Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and behavioral impairments. Despite extensive research efforts, effective treatment options for AD remain limited. Recently, gene therapy has emerged as a promising avenue for targeted intervention in the pathogenesis of AD. This review will provide an overview of clinical and preclinical studies where gene therapy techniques have been utilized in the context of AD, highlighting their potential as novel therapeutic strategies. While challenges remain, ongoing research and technological advancement continue to enhance the potential of gene therapy as a targeted and personalized therapeutic approach for AD.

Anaesthesia-induced Changes in Genomic Expression Leading to Neurodegeneration

General anaesthetics (GA) have been in continuous clinical use for more than 170 years, with millions of young and elderly populations exposed to GA to relieve perioperative discomfort and carry out invasive examinations. Preclinical studies have shown that neonatal rodents with acute and chronic exposure to GA suffer from memory and learning deficits, likely due to an imbalance between excitatory and inhibitory neurotransmitters, which has been linked to neurodevelopmental disorders. However, the mechanisms behind anaesthesia-induced alterations in late postnatal mice have yet to be established. In this narrative review, we present the current state of knowledge on early life anaesthesia exposure-mediated alterations of genetic expression, focusing on insights gathered on propofol, ketamine, and isoflurane, as well as the relationship between network effects and subsequent biochemical changes that lead to long-term neurocognitive abnormalities. Our review provides strong evidence and a clear picture of anaesthetic agents' pathological events and associated transcriptional changes, which will provide new insights for researchers to elucidate the core ideas and gain an in-depth understanding of molecular and genetic mechanisms. These findings are also helpful in generating more evidence for understanding the exacerbated neuropathology, impaired cognition, and LTP due to acute and chronic exposure to anaesthetics, which will be beneficial for the prevention and treatment of many diseases, such as Alzheimer's disease. Given the many procedures in medical practice that require continuous or multiple exposures to anaesthetics, our review will provide great insight into the possible adverse impact of these substances on the human brain and cognition.

Mechanisms and Functions of Activity-Regulated Cytoskeleton-Associated Protein in Synaptic Plasticity

Activity-regulated cytoskeleton-associated protein (Arc) is one of the most important regulators of cognitive functions in the brain regions. As a hub protein, Arc plays different roles in modulating synaptic plasticity. Arc supports the maintenance of long-term potentiation (LTP) by regulating actin cytoskeletal dynamics, while it guides the endocytosis of AMPAR in long-term depression (LTD). Moreover, Arc can self-assemble into capsids, leading to a new way of communicating among neurons. The transcription and translation of the immediate early gene Arc are rigorous procedures guided by numerous factors, and RNA polymerase II (Pol II) is considered to regulate the precise timing dynamics of gene expression. Since astrocytes can secrete brain-derived neurotrophic factor (BDNF) and L-lactate, their unique roles in Arc expression are emphasized. Here, we review the entire process of Arc expression and summarize the factors that can affect Arc expression and function, including noncoding RNAs, transcription factors, and posttranscriptional regulations. We also attempt to review the functional states and mechanisms of Arc in modulating synaptic plasticity. Furthermore, we discuss the recent progress in understanding the roles of Arc in the occurrence of major neurological disorders and provide new thoughts for future research on Arc.

Physiological Roles of β-amyloid in Regulating Synaptic Function: Implications for AD Pathophysiology

The physiological functions of endogenous amyloid-β (Aβ), which plays important role in the pathology of Alzheimer's disease (AD), have not been paid enough attention. Here, we review the multiple physiological effects of Aβ, particularly in regulating synaptic transmission, and the possible mechanisms, in order to decipher the real characters of Aβ under both physiological and pathological conditions. Some worthy studies have shown that the deprivation of endogenous Aβ gives rise to synaptic dysfunction and cognitive deficiency, while the moderate elevation of this peptide enhances long term potentiation and leads to neuronal hyperexcitability. In this review, we provide a new view for understanding the role of Aβ in AD pathophysiology from the perspective of physiological meaning.

Secreted Amyloid Precursor Protein Alpha (sAPPα) Regulates the Cellular Proteome and Secretome of Mouse Primary Astrocytes

Secreted amyloid precursor protein alpha (sAPPα), processed from a parent mammalian brain protein, amyloid precursor protein, can modulate learning and memory. Recently it has been shown to modulate the transcriptome and proteome of human neurons, including proteins with neurological functions. Here, we analysed whether the acute administration of sAPPα facilitated changes in the proteome and secretome of mouse primary astrocytes in culture. Astrocytes contribute to the neuronal processes of neurogenesis, synaptogenesis and synaptic plasticity. Cortical mouse astrocytes in culture were exposed to 1 nM sAPPα, and changes in both the whole-cell proteome (2 h) and the secretome (6 h) were identified with Sequential Window Acquisition of All Theoretical Fragment Ion Spectra-Mass Spectrometry (SWATH-MS). Differentially regulated proteins were identified in both the cellular proteome and secretome that are involved with neurologically related functions of the normal physiology of the brain and central nervous system. Groups of proteins have a relationship to APP and have roles in the modulation of cell morphology, vesicle dynamics and the myelin sheath. Some are related to pathways containing proteins whose genes have been previously implicated in Alzheimer's disease (AD). The secretome is also enriched in proteins related to Insulin Growth Factor 2 (IGF2) signaling and the extracellular matrix (ECM). There is the promise that a more specific investigation of these proteins will help to understand the mechanisms of how sAPPα signaling affects memory formation.

Age-Dependent Dysregulation of APP in Neuronal and Skin Cells from Fragile X Individuals

Fragile X syndrome (FXS) is the most common form of monogenic intellectual disability and autism, caused by the absence of the functional fragile X messenger ribonucleoprotein 1 (FMRP). FXS features include increased and dysregulated protein synthesis, observed in both murine and human cells. Altered processing of the amyloid precursor protein (APP), consisting of an excess of soluble APPα (sAPPα), may contribute to this molecular phenotype in mice and human fibroblasts. Here we show an age-dependent dysregulation of APP processing in fibroblasts from FXS individuals, human neural precursor cells derived from induced pluripotent stem cells (iPSCs), and forebrain organoids. Moreover, FXS fibroblasts treated with a cell-permeable peptide that decreases the generation of sAPPα show restored levels of protein synthesis. Our findings suggest the possibility of using cell-based permeable peptides as a future therapeutic approach for FXS during a defined developmental window.

Secreted Amyloid Precursor Protein Alpha, a Neuroprotective Protein in the Brain Has Widespread Effects on the Transcriptome and Proteome of Human Inducible Pluripotent Stem Cell-Derived Glutamatergic Neurons Related to Memory Mechanisms

Secreted amyloid precursor protein alpha (sAPPα) processed from a parent human brain protein, APP, can modulate learning and memory. It has potential for development as a therapy preventing, delaying, or even reversing Alzheimer’s disease. In this study a comprehensive analysis to understand how it affects the transcriptome and proteome of the human neuron was undertaken. Human inducible pluripotent stem cell (iPSC)-derived glutamatergic neurons in culture were exposed to 1 nM sAPPα over a time course and changes in the transcriptome and proteome were identified with RNA sequencing and Sequential Window Acquisition of All THeoretical Fragment Ion Spectra-Mass Spectrometry (SWATH-MS), respectively. A large subset (∼30%) of differentially expressed transcripts and proteins were functionally involved with the molecular biology of learning and memory, consistent with reported links of sAPPα to memory enhancement, as well as neurogenic, neurotrophic, and neuroprotective phenotypes in previous studies. Differentially regulated proteins included those encoded in previously identified Alzheimer’s risk genes, APP processing related proteins, proteins involved in synaptogenesis, neurotransmitters, receptors, synaptic vesicle proteins, cytoskeletal proteins, proteins involved in protein and organelle trafficking, and proteins important for cell signalling, transcriptional splicing, and functions of the proteasome and lysosome. We have identified a complex set of genes affected by sAPPα, which may aid further investigation into the mechanism of how this neuroprotective protein affects memory formation and how it might be used as an Alzheimer’s disease therapy.

Brothers in arms: proBDNF/BDNF and sAPPα/Aβ-signaling and their common interplay with ADAM10, TrkB, p75NTR, sortilin, and sorLA in the progression of Alzheimer's disease

Brain-derived neurotrophic factor (BDNF) is an important modulator for a variety of functions in the central nervous system (CNS). A wealth of evidence, such as reduced mRNA and protein level in the brain, cerebrospinal fluid (CSF), and blood samples of Alzheimer's disease (AD) patients implicates a crucial role of BDNF in the progression of this disease. Especially, processing and subcellular localization of BDNF and its receptors TrkB and p75 are critical determinants for survival and death in neuronal cells. Similarly, the amyloid precursor protein (APP), a key player in Alzheimer's disease, and its cleavage fragments sAPPα and Aβ are known for their respective roles in neuroprotection and neuronal death. Common features of APP- and BDNF-signaling indicate a causal relationship in their mode of action. However, the interconnections of APP- and BDNF-signaling are not well understood. Therefore, we here discuss dimerization properties, localization, processing by α- and γ-secretase, relevance of the common interaction partners TrkB, p75, sorLA, and sortilin as well as shared signaling pathways of BDNF and sAPPα.

Amyloid Beta Dynamics in Biological Fluids-Therapeutic Impact

Despite the significant impact of Alzheimer's disease (AD) at individual and socioeconomic levels and the numerous research studies carried out on this topic over the last decades, the treatments available in daily clinical practice remain less than satisfactory. Among the accepted etiopathogenic hypotheses, the amyloidogenic pathway theory, although intensively studied and even sometimes controversial, is still providing relevant theoretical elements for understanding the etiology of AD and for the further development of possible therapeutic tools. In this sense, this review aims to offer new insights related to beta amyloid (Aβ), an essential biomarker in AD. First the structure and function of Aβ in normal and pathological conditions are presented in detail, followed by a discussion on the dynamics of Aβ at the level of different biological compartments. There is focus on Aβ elimination modalities at central nervous system (CNS) level, and clearance via the blood-brain barrier seems to play a crucial/dominant role. Finally, different theoretical and already-applied therapeutic approaches for CNS Aβ elimination are presented, including the recent "peripheral sink therapeutic strategy" and "cerebrospinal fluid sinks therapeutic strategy". These data outline the need for a multidisciplinary approach designed to deliver a solution to stimulate Aβ clearance in more direct ways, including from the cerebrospinal fluid level.

Past, present and future of therapeutic strategies against amyloid-β peptides in Alzheimer's disease: a systematic review

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in ageing, affecting around 46 million people worldwide but few treatments are currently available. The etiology of AD is still puzzling, and new drugs development and clinical trials have high failure rates. Urgent outline of an integral (multi-target) and effective treatment of AD is needed. Accumulation of amyloid-β (Aβ) peptides is considered one of the fundamental neuropathological pillars of the disease, and its dyshomeostasis has shown a crucial role in AD onset. Therefore, many amyloid-targeted therapies have been investigated. Here, we will systematically review recent (from 2014) investigational, follow-up and review studies focused on anti-amyloid strategies to summarize and analyze their current clinical potential. Combination of anti-Aβ therapies with new developing early detection biomarkers and other therapeutic agents acting on early functional AD changes will be highlighted in this review. Near-term approval seems likely for several drugs acting against Aβ, with recent FDA approval of a monoclonal anti-Aβ oligomers antibody -aducanumab- raising hopes and controversies. We conclude that, development of oligomer-epitope specific Aβ treatment and implementation of multiple improved biomarkers and risk prediction methods allowing early detection, together with therapies acting on other factors such as hyperexcitability in early AD, could be the key to slowing this global pandemic.

Rho-associated kinases contribute to the regulation of tau phosphorylation and amyloid metabolism during neuronal plasticity

BACKGROUND

Neural plasticity under physiological condition develops together with normal tau phosphorylation and amyloid precursor protein (APP) processing. Since restoration of PI3-kinase signaling has therapeutic potential in Alzheimer's disease, we investigated plasticity-related changes in tau and APP metabolism by the selective Rho-kinase inhibitor fasudil.

METHODS

Field potentials composed of a field excitatory post-synaptic potential (fEPSP) and a population spike (PS) were recorded from a granule cell layer of the dentate gyrus. Plasticity of synaptic strength and neuronal function was induced by strong tetanic stimulation (HFS) and low-frequency stimulation (LFS) patterns. Infusions of saline or fasudil were given for 1 h starting from the application of the induction protocols. Total and phosphorylated tau levels and soluble APPα levels were measured in the hippocampus, which was removed after at least 1 h post-induction period.

RESULTS

Fasudil infusion resulted in attenuation of fEPSP slope and PS amplitude in response to both HFS and LFS. Fasudil reduced total tau and phosphorylated tau at residue Thr¹⁸¹ in the HFS-stimulated hippocampus, while Thr²³¹ phosphorylation was reduced by fasudil treatment in the LFS-stimulated hippocampus. Ser⁴¹⁶ phosphorylation was increased by fasudil treatment in both HFS- and LFS-stimulated hippocampus. Fasudil significantly increased soluble APPα in LFS-stimulated hippocampus, but not in HFS-stimulated hippocampus.

CONCLUSION

In light of our findings, we suggest that increased activity of Rho kinase could trigger a mechanism that goes awry during synaptic plasticity which is reversed by a Rho-kinase inhibitor. Thus, Rho-kinase inhibition might be a therapeutic target in cognitive disorders.

Secreted Amyloid Precursor Protein-Alpha Enhances LTP Through the Synthesis and Trafficking of Ca2+-Permeable AMPA Receptors

Regulation of AMPA receptor expression by neuronal activity and neuromodulators is critical to the expression of both long-term potentiation (LTP) and memory. In particular, Ca²⁺-permeable AMPARs (CP-AMPAR) play a unique role in these processes due to their transient, activity-regulated expression at synapses. Secreted amyloid precursor protein-alpha (sAPPα), a metabolite of the parent amyloid precursor protein (APP) has been previously shown to enhance hippocampal LTP as well as memory formation in both normal animals and in Alzheimer’s disease models. In earlier work we showed that sAPPα promotes trafficking of GluA1-containing AMPARs to the cell surface and specifically enhances synthesis of GluA1. To date it is not known whether de novo synthesized GluA1 form CP-AMPARs or how they contribute to sAPPα-mediated plasticity. Here, using fluorescent non-canonical amino acid tagging–proximity ligation assay (FUNCAT-PLA), we show that brief treatment of primary rat hippocampal neurons with sAPPα (1 nM, 30 min) rapidly enhanced the cell-surface expression of de novo GluA1 homomers and reduced levels of de novo GluA2, as well as extant GluA2/3-AMPARs. The de novo GluA1-containing AMPARs were localized to extrasynaptic sites and later internalized by sAPPα-driven expression of the activity-regulated cytoskeletal-associated protein, Arc. Interestingly, longer exposure to sAPPα increased synaptic levels of GluA1/2 AMPARs. Moreover, the sAPPα-mediated enhancement of LTP in area CA1 of acute hippocampal slices was dependent on CP-AMPARs. Together, these findings show that sAPPα engages mechanisms which specifically enhance the synthesis and cell-surface expression of GluA1 homomers, underpinning the sAPPα-driven enhancement of synaptic plasticity in the hippocampus.

TIP60 in aging and neurodegeneration

Epigenetic modification of chromatin, including histone methylation and acetylation, plays critical roles in eukaryotic cells and has a significant impact on chromatin structure/accessibility, gene regulation and, susceptibility to aging, neurodegenerative disease, cancer, and other age-related diseases. This article reviews the current advances on TIP60/KAT5, a major histone acetyltransferase with diverse functions in eukaryotes, with emphasis on its regulation of autophagy, proteasome-dependent protein turnover, RNA transcription, DNA repair, circadian rhythms, learning and memory, and other neurological functions implicated in aging and neurodegeneration. Moreover, the promising therapeutic potential of TIP60 is discussed to target Alzheimer's disease and other neurological diseases.

Uniting homeostatic plasticity and exosome biology: A revision of the conceptual framework for drug discovery in neurodegenerative diseases?

Neurodegenerative diseases (NDDs) are in need of new drug discovery approaches. Our previous systematic analyses of Huntington's Disease (HD) literature for protein-protein interactors (PPIs) and modifiers of mutant Huntingtin-driven phenotypes revealed enrichment for PPIs of genes required for homeostatic synaptic plasticity (HSP) and exosome (EV) function and exosomal proteins, which in turn highly overlapped each other and with PPIs of genes associated with other NDDs. We proposed that HSP and EVs are linked to each other and are also involved in NDD pathophysiology. Recent studies showed that HSP is indeed altered in HD and AD, and that presynaptic homeostatic plasticity in motoneurons compensates for ALS pathology. Eliminating it causes earlier degeneration and death. If this holds true in other NDDs, drug discovery in animal models should then include elucidation of homeostatic compensation that either masks phenotypes of physiologically expressed mutant genes or are overridden by their overexpression. In this new conceptual framework, enhancing such underlying homeostatic compensation forms the basis for novel therapeutic strategies to slow progression of NDDs. Moreover, if EVs are linked to HSP, then their ability to penetrate the brain, target cell types, deliver miRNA and other molecules can be leveraged to develop attractive drug modalities. Testing this new framework is posed as four questions on model development and mechanistic studies progressing from higher throughput platforms to mouse models. Similar approaches may apply to other CNS disorders including schizophrenia, autism, Rett and Fragile X syndromes due to potential links of their susceptibility genes to HSP and EVs.

The novel DYRK1A inhibitor KVN93 regulates cognitive function, amyloid-beta pathology, and neuroinflammation

Regulating amyloid beta (Aβ) pathology and neuroinflammatory responses holds promise for the treatment of Alzheimer's disease (AD) and other neurodegenerative and/or neuroinflammation-related diseases. In this study, the effects of KVN93, an inhibitor of dual-specificity tyrosine phosphorylation-regulated kinase-1A (DYRK1A), on cognitive function and Aβ plaque levels and the underlying mechanism of action were evaluated in 5x FAD mice (a mouse model of AD). KVN93 treatment significantly improved long-term memory by enhancing dendritic synaptic function. In addition, KVN93 significantly reduced Aβ plaque levels in 5x FAD mice by regulating levels of the Aβ degradation enzymes neprilysin (NEP) and insulin-degrading enzyme (IDE). Moreover, Aβ-induced microglial and astrocyte activation were significantly suppressed in the KVN-treated 5xFAD mice. KVN93 altered neuroinflammation induced by LPS in microglial cells but not primary astrocytes by regulating TLR4/AKT/STAT3 signaling, and in wild-type mice injected with LPS, KVN93 treatment reduced microglial and astrocyte activation. Overall, these results suggest that the novel DYRK1A inhibitor KVN93 is a potential therapeutic drug for regulating cognitive/synaptic function, Aβ plaque load, and neuroinflammatory responses in the brain.

Galantamine-Memantine combination in the treatment of Alzheimer's disease and beyond

Alzheimer's disease (AD) is the most prevalent form of dementia in the elderly population worldwide. Despite the major unmet clinical need, no new medications for the treatment of AD have been approved since 2003. Galantamine is an acetylcholinesterase inhibitor that is also a positive allosteric modulator at the α4β2 and α7nACh receptors. Memantine is an N-methyl-d-aspartate receptor modulator/agonist. Both galantamine and memantine are FDA-approved medications for the treatment of AD. The objective of this review is to highlight the potential of the galantamine-memantine combination to conduct randomized controlled trials (RCTs) in AD. Several studies have shown the combination to be effective. Neurodegenerative diseases involve multiple pathologies; therefore, combination treatment appears to be a rational approach. Although underutilized, the galantamine-memantine combination is the standard of care in the treatment of AD. Positive RCTs with the combination with concurrent improvement in symptoms and biomarkers may lead to FDA approval, which may lead to greater utilization of this combination in clinical practice.