Peroxisome proliferator-activated receptor agonists: A new hope towards the management of alcoholic liver disease.

In this editorial, we examine a paper by Koizumi et al, on the role of peroxisome proliferator-activated receptor (PPAR) agonists in alcoholic liver disease (ALD). The study determined whether elafibranor protected the intestinal barrier and reduced liver fibrosis in a mouse model of ALD. The study also underlines the role of PPARs in intestinal barrier function and lipid homeostasis, which are both affected by ALD. Effective therapies are necessary for ALD because it is a critical health issue that affects people worldwide. This editorial analyzes the possibility of PPAR agonists as treatments for ALD. As key factors of inflammation and metabolism, PPARs offer multiple methods for managing the complex etiology of ALD. We assess the abilities of PPARα, PPARγ, and PPARß/δ agonists to prevent steatosis, inflammation, and fibrosis due to liver diseases. Recent research carried out in preclinical and clinical settings has shown that PPAR agonists can reduce the severity of liver disease. This editorial discusses the data analyzed and the obstacles, advantages, and mechanisms of action of PPAR agonists for ALD. Further research is needed to understand the efficacy, safety, and mechanisms of PPAR agonists for treating ALD.

Isolation and Detection of Pathological Tau Species in a Tauopathy Mouse Model.

Tau protein in Alzheimer's disease (AD) and tauopathies becomes insoluble due to hyperphosphorylation, conformational alterations, and aggregation. To analyze insoluble tau and pathological tau species, this study employs a methodology that utilizes wild-type and transgenic tau mice (P310S Tau) tissue extraction using 1% Sarkosyl or N-Lauroylsarcosine sodium salt and the radio immunoprecipitation assay (RIPA) buffer. However, the commonly used methods to study the insoluble tau fraction using detergents like Sarkosyl and RIPA require a large amount of homogenate, which can pose challenges when dealing with small tissue samples. Additionally, the study employs immunohistochemistry to visualize and quantify the pathological tau species in the brain tissue of transgenic mice, aiming to identify and analyze pathological tau species such as hyperphosphorylated tau to further our understanding of tauopathies such as Alzheimer's disease.

Gastrointestinal Manifestations of SARS-CoV-2: Transmission, Pathogenesis, Immunomodulation, Microflora Dysbiosis, and Clinical Implications.

The clinical manifestation of COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in the respiratory system of humans is widely recognized. There is increasing evidence suggesting that SARS-CoV-2 possesses the capability to invade the gastrointestinal (GI) system, leading to the manifestation of symptoms such as vomiting, diarrhea, abdominal pain, and GI lesions. These symptoms subsequently contribute to the development of gastroenteritis and inflammatory bowel disease (IBD). Nevertheless, the pathophysiological mechanisms linking these GI symptoms to SARS-CoV-2 infection remain unelucidated. During infection, SARS-CoV-2 binds to angiotensin-converting enzyme 2 and other host proteases in the GI tract during the infection, possibly causing GI symptoms by damaging the intestinal barrier and stimulating inflammatory factor production, respectively. The symptoms of COVID-19-induced GI infection and IBD include intestinal inflammation, mucosal hyperpermeability, bacterial overgrowth, dysbiosis, and changes in blood and fecal metabolomics. Deciphering the pathogenesis of COVID-19 and understanding its exacerbation may provide insights into disease prognosis and pave the way for the discovery of potential novel targets for disease prevention or treatment. Besides the usual transmission routes, SARS-CoV-2 can also be transmitted via the feces of an infected person. Hence, it is crucial to implement preventive and control measures in order to mitigate the fecal-to-oral transmission of SARS-CoV-2. Within this context, the identification and diagnosis of GI tract symptoms during these infections assume significance as they facilitate early detection of the disease and the development of targeted therapeutics. The present review discusses the receptors, pathogenesis, and transmission of SARS-CoV-2, with a particular focus on the induction of gut immune responses, the influence of gut microbes, and potential therapeutic targets against COVID-19-induced GI infection and IBD.

Interaction of Tau with Kinesin-1: Effect of Kinesin-1 Heavy Chain Elimination on Autophagy-Mediated Mutant Tau Degradation.

Natively unfolded tau has a low propensity to form aggregates, but in tauopathies, such as Alzheimer's disease (AD), tau aggregates into paired helical filaments (PHFs) and neurofibrillary tangles (NFTs). Multiple intracellular transport pathways utilize kinesin-1, a plus-end-directed microtubule-based motor. Kinesin-1 is crucial in various neurodegenerative diseases as it transports multiple cargoes along the microtubules (MT). Kinesin-1 proteins cannot progress along MTs due to an accumulation of tau on their surfaces. Although kinesin-1-mediated neuronal transport dysfunction is well-documented in other neurodegenerative diseases, its role in AD has received less attention. Very recently, we have shown that knocking down and knocking out of kinesin-1 heavy chain (KIF5B KO) expression significantly reduced the level and stability of tau in cells and tau transgenic mice, respectively. Here, we report that tau interacts with the motor domain of KIF5B in vivo and in vitro, possibly through its microtubule-binding repeat domain. This interaction leads to the inhibition of the ATPase activity of the motor domain. In addition, the KIF5B KO results in autophagy initiation, which subsequently assists in tau degradation. The mechanisms behind KIF5B KO-mediated tau degradation seem to involve its interaction with tau, promoting the trafficking of tau through retrograde transport into autophagosomes for subsequent lysosomal degradation of tau. Our results suggest how KIF5B removal facilitates the movement of autophagosomes toward lysosomes for efficient tau degradation. This mechanism can be enabled through the downregulation of kinesin-1 or the disruption of the association between kinesin-1 and tau, particularly in cases when neurons perceive disturbances in intercellular axonal transport.

Reduction of kinesin I heavy chain decreases tau hyperphosphorylation, aggregation, and memory impairment in Alzheimer's disease and tauopathy models.

Many neurodegenerative diseases, such as Alzheimer's disease (AD) and frontotemporal dementia with Parkinsonism linked to chromosome 17, are characterized by tau pathology. Numerous motor proteins, many of which are involved in synaptic transmission, mediate transport in neurons. Dysfunction in motor protein-mediated neuronal transport mechanisms occurs in several neurodegenerative disorders but remains understudied in AD. Kinesins are the most important molecular motor proteins required for microtubule-dependent transport in neurons, and kinesin-1 is crucial for neuronal transport among all kinesins. Although kinesin-1 is required for normal neuronal functions, the dysfunction of these motor domains leading to neurodegenerative diseases is not fully understood. Here, we reported that the kinesin-I heavy chain (KIF5B), a key molecular motor protein, is involved in tau homeostasis in AD cells and animal models. We found that the levels of KIF5B in P301S tau mice are high. We also found that the knockdown and knockout (KO) of KIFf5B significantly decreased the tau stability, and overexpression of KIF5B in KIF5B-KO cells significantly increased the expression of phosphorylated and total tau levels. This suggested that KIF5B might prevent tau accumulation. By conducting experiments on P301S tau mice, we showed that partially reducing KIF5B levels can reduce hyperphosphorylation of the human tau protein, formation of insoluble aggregates, and memory impairment. Collectively, our results suggested that decreasing KIF5B levels is sufficient to prevent and/or slow down abnormal tau behavior of AD and other tauopathies.

Animal models for SARS-CoV-2 and SARS-CoV-1 pathogenesis, transmission and therapeutic evaluation.

There is a critical need to develop animal models to alleviate vaccine and drug development difficulties against zoonotic viral infections. The coronavirus family, which includes severe acute respiratory syndrome coronavirus 1 and severe acute respiratory syndrome coronavirus 2, crossed the species barrier and infected humans, causing a global outbreak in the 21st century. Because humans do not have pre-existing immunity against these viral infections and with ethics governing clinical trials, animal models are therefore being used in clinical studies to facilitate drug discovery and testing efficacy of vaccines. The ideal animal models should reflect the viral replication, clinical signs, and pathological responses observed in humans. Different animal species should be tested to establish an appropriate animal model to study the disease pathology, transmission and evaluation of novel vaccine and drug candidates to treat coronavirus disease 2019. In this context, the present review summarizes the recent progress in developing animal models for these two pathogenic viruses and highlights the utility of these models in studying SARS-associated coronavirus diseases.

Alzheimer's Disease and other Tauopathies: Exploring Efficacy of Medicinal Plant-derived Compounds in Alleviating Tau-mediated Neurodegeneration.

Alzheimer's disease (AD), a major form of dementia, has been reported to affect more than 50 million people worldwide. It is characterized by the presence of amyloid-ß (Aß) plaques and hyperphosphorylated Tau-associated neurofibrillary tangles in the brain. Apart from AD, microtubule (MT)-associated protein Tau is also involved in other neurodegenerative diseases called tauopathies, including Pick's disease, frontotemporal lobar degeneration, progressive supranuclear palsy, and corticobasal degeneration. The recent unsuccessful phase III clinical trials related to Aß- targeted therapeutic drugs have indicated that alternative targets, such as Tau, should be studied to discover more effective and safer drugs. Recent drug discovery approaches to reduce AD-related Tau pathologies are primarily based on blocking Tau aggregation, inhibiting Tau phosphorylation, compensating impaired Tau function with MT-stabilizing agents, and targeting the degradation pathways in neuronal cells to degrade Tau protein aggregates. Owing to several limitations of the currently available Tau-directed drugs, further studies are required to generate further effective and safer Tau-based disease-modifying drugs. Here, we review the studies focused on medicinal plant- derived compounds capable of modulating the Tau protein, which is significantly elevated and hyperphosphorylated in AD and other tauopathies. We have mainly considered the studies focused on Tau protein as a therapeutic target. We have reviewed several pertinent papers retrieved from PubMed and ScienceDirect using relevant keywords, with a primary focus on the Tau-targeting compounds from medicinal plants. These compounds include indolines, phenolics, flavonoids, coumarins, alkaloids, and iridoids, which have been scientifically proven to be Tau-targeting candidates for the treatment of AD.

Protopine promotes the proteasomal degradation of pathological tau in Alzheimer's disease models via HDAC6 inhibition.

BACKGROUND: Collective evidences have indicated that intracellular accumulation of hyperphosphorylated tau forms neurofibrillary tangles in the brain, which impairs memory, cognition and affects social activities in Alzheimer's disease (AD). PURPOSE: To investigate the tau-reducing, and memory-enhancing properties of protopine (PRO), a natural alkaloid isolated from Chinese herbal medicine Corydalis yanhusuo (Yanhusuo in Chinese). STUDY DESIGN: By using Histone deacetylase 6 (HDAC6) profiling and immunoprecipitation assays, we assessed that PRO mediated the heat shock protein 90 (HSP90) chaperonic activities for the degradation of pathological tau in AD cell culture models. To study the efficacy of PRO in vivo, we employed 3xTg-AD and P301S tau mice models. METHODS: Liquid chromatography/quadrupole time-of-flight mass spectrometry was used to analyze the pharmacokinetic profile of PRO. Seven-month-old 3xTg-AD mice and 1.5-month-old P301S mice were administered PRO (1 and 2.5 mg/kg) orally every day. Morris water maze, contextual fear conditioning and rotarod assays were applied for studying memory functions. Sarkosyl differential centrifugation was used to analyze soluble and insoluble tau. Immunohistochemical analysis were performed to determine tau deposits in AD mice's brain sections. Molecular docking, binding affinity studies and primary cell culture studies were performed to demonstrate the mechanism of action of PRO in silico and in vitro. RESULTS: Our pharmacokinetic profiling demonstrated that PRO significantly entered the brain at a concentration of 289.47 ng/g, and specifically attenuated tau pathology, improved learning and memory functions in both 3xTg-AD and P301S mice. Docking, binding affinity studies, and fluorometric assays demonstrated that PRO directly bound to the catalytic domain 1 (CD1) of HDAC6 and down-regulated its activity. In primary cortical neurons, PRO enhanced acetylation of α-tubulin, indicating HDAC6 inhibition. Meanwhile, PRO promoted the ubiquitination of tau and recruited heat shock protein 70 (HSP70) and heat shock cognate complex 71 (HSC70) for the degradation of pathological tau via the ubiquitin-proteasomal system (UPS). CONCLUSION: We identified PRO as a natural HDAC6 inhibitor that attenuated tau pathology and improved memory dysfunctions in AD mice. The findings from this study provides a strong justification for future clinical development of plant-derived protopine as a novel agent for the treatment of tau-related neurodegenerative diseases.

Qingyangshen mitigates amyloid-ß and Tau aggregate defects involving PPARα-TFEB activation in transgenic mice of Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is the most common neurodegenerative disease. Deposition of amyloid ß plaques (Aß) and neurofibrillary tangles (NFTs) is the key pathological hallmark of AD. Accumulating evidence suggest that impairment of autophagy-lysosomal pathway (ALP) plays key roles in AD pathology. PURPOSE: The present study aims to assess the neuroprotective effects of Qingyangshen (QYS), a Chinese herbal medicine, in AD cellular and animal models and to determine its underlying mechanisms involving ALP regulation. METHODS: QYS extract was prepared and its chemical components were characterized by LC/MS. Then the pharmacokinetics and acute toxicity of QYS extract were evaluated. The neuroprotective effects of QYS extract were determined in 3XTg AD mice, by using a series of behavioral tests and biochemical assays, and the mechanisms were examined in vitro. RESULTS: Oral administration of QYS extract improved learning and spatial memory, reduced carboxy-terminal fragments (CTFs), amyloid precursor protein (APP), Aß and Tau aggregates, and inhibited microgliosis and astrocytosis in the brains of 3XTg mice. Mechanistically, QYS extract increased the expression of PPARα and TFEB, and promoted ALP both in vivo and in vitro. CONCLUSION: QYS attenuates AD pathology, and improves cognitive function in 3XTg mice, which may be mediated by activation of PPARα-TFEB pathway and the subsequent ALP enhancement. Therefore, QYS may be a promising herbal material for further anti-AD drug discovery.

NRBF2 is a RAB7 effector required for autophagosome maturation and mediates the association of APP-CTFs with active form of RAB7 for degradation.

NRBF2 is a component of the class III phosphatidylinositol 3-kinase (PtdIns3K) complex. Our previous study has revealed its role in regulating ATG14-associated PtdIns3K activity for autophagosome initiation. In this study, we revealed an unknown mechanism by which NRBF2 modulates autophagosome maturation and APP-C-terminal fragment (CTF) degradation. Our data showed that NRBF2 localized at autolysosomes, and loss of NRBF2 impaired autophagosome maturation. Mechanistically, NRBF2 colocalizes with RAB7 and is required for generation of GTP-bound RAB7 by interacting with RAB7 GEF CCZ1-MON1A and maintaining the GEF activity. Specifically, NRBF2 regulates CCZ1-MON1A interaction with PI3KC3/VPS34 and CCZ1-associated PI3KC3 kinase activity, which are required for CCZ1-MON1A GEF activity. Finally, we showed that NRBF2 is involved in APP-CTF degradation and amyloid beta peptide production by maintaining the interaction between APP and the CCZ1-MON1A-RAB7 module to facilitate the maturation of APP-containing vesicles. Overall, our study revealed a pivotal role of NRBF2 as a new RAB7 effector in modulating autophagosome maturation, providing insight into the molecular mechanism of NRBF2-PtdIns3K in regulating RAB7 activity for macroautophagy/autophagy maturation and Alzheimer disease-associated protein degradation..Abbreviations: 3xTg AD, triple transgenic mouse for Alzheimer disease; Aß, amyloid beta peptide; Aß1-40, amyloid beta peptide 1-40; Aß1-42, amyloid beta peptide 1-42; AD, Alzheimer disease; APP, amyloid beta precursor protein; APP-CTFs, APP C-terminal fragments; ATG, autophagy related; ATG5, autophagy related 5; ATG7, autophagy related 7; ATG14, autophagy related 14; CCD, coiled-coil domain; CCZ1, CCZ1 homolog, vacuolar protein trafficking and biogenesis associated; CHX, cycloheximide; CQ, chloroquine; DAPI, 4',6-diamidino-2-phenylindole; dCCD, delete CCD; dMIT, delete MIT; FYCO1, FYVE and coiled-coil domain autophagy adaptor 1; FYVE, Fab1, YGL023, Vps27, and EEA1; GAP, GTPase-activating protein; GDP, guanine diphosphate; GEF, guanine nucleotide exchange factor; GTP, guanine triphosphate; GTPase, guanosine triphosphatase; HOPS, homotypic fusion and vacuole protein sorting; ILVs, endosomal intralumenal vesicles; KD, knockdown; KO, knockout; LAMP1, lysosomal associated membrane protein 1; MAP1LC3/LC3, microtubule associated protein 1 light chain 3; MLVs, multilamellar vesicles; MON1A, MON1 homolog A, secretory trafficking associated; NRBF2, nuclear receptor binding factor 2; PtdIns3K, class III phosphatidylinositol 3-kinase; PtdIns3P, phosphatidylinositol-3-phosphate; RILP, Rab interacting lysosomal protein; SNARE, soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SQSTM1/p62, sequestosome 1; UVRAG, UV radiation resistance associated; VPS, vacuolar protein sorting; WT, wild type.

A Mechanistic Review on Medicinal Mushrooms-Derived Bioactive Compounds: Potential Mycotherapy Candidates for Alleviating Neurological Disorders.

According to the World Health Organization, neurological and neurodegenerative diseases are highly debilitating and pose the greatest threats to public health. Diseases of the nervous system are caused by a particular pathological process that negatively affects the central and peripheral nervous systems. These diseases also lead to the loss of neuronal cell function, which causes alterations in the nervous system structure, resulting in the degeneration or death of nerve cells throughout the body. This causes problems with movement (ataxia) and mental dysfunction (dementia), both of which are commonly observed symptoms in Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. Medicinal mushrooms are higher fungi with nutraceutical properties and are low in calories and fat. They are also a rich source of nutrients and bioactive compounds such as carbohydrates, proteins, fibers, and vitamins that have been used in the treatment of many ailments. Medicinal mushrooms such as Pleurotus giganteus, Ganoderma lucidium, and Hericium erinaceus are commonly produced worldwide for use as health supplements and medicine. Medicinal mushrooms and their extracts have a large number of bioactive compounds, such as polysaccharide ß-glucan, or polysaccharide-protein complexes, like lectins, lactones, terpenoids, alkaloids, antibiotics, and metal-chelating agents. This review will focus on the role of the medicinal properties of different medicinal mushrooms that contain bioactive compounds with a protective effect against neuronal dysfunction. This information will facilitate the development of drugs against neurodegenerative diseases.

A Novel Species of Penicillium With Inhibitory Effects Against Pyricularia oryzae and Fungal Pathogens Inducing Citrus Diseases.

A novel species of Penicillium, proposed as P. linzhiense sp.nov was isolated from soil collected in Linzhi Town, Linzhi County, Tibet Autonomous Region, China. DNA sequence analyses from eight different gene regions indicate that the isolate represents a novel species and most closely related to P. janczewskii. The phylogenetic analysis based on a concatenated dataset of three genes, ITS, CaM, and BenA, also confirmed the placement of the novel species within the Canescentia section of the genus Penicillium. Differences in morphology among similar species are detailed and single gene phylogenies based on ITS, CaM and BenA genes as well as a multi-loci gene phylogeny are presented. Cultural studies were performed to study inhibitory activities on plant pathogens. The results reveal a notable antifungal activity against Pyricularia oryzae causing rice blast with an inhibition rate up to 77%, while for other three citrus pathogens, Diaporthe citri, Phyllosticta citrichinaensis, and Colletotrichum gloeosporioides, inhibition rate was 40, 50, and 55% respectively. No noticeable effects were observed for Fusarium graminearum, Botryosphaeria kuwatsukai, and Rhizoctonia solani. Interestingly, unlike other reported members of Canescentia, P. linzhiense showed no antagonistic effect on root rotting fungi. The new taxon isolated here has the potential to be used as a biocontrol agent especially for economically important phytopathogens or emerging pathogens on diseases occurring on citrus or rice.

NeuroDefend, a novel Chinese medicine, attenuates amyloid-ß and tau pathology in experimental Alzheimer's disease models.

Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder. Amyloid-ß (Aß) and hyper-phosphorylated tau accumulation are accountable for the progressive neuronal loss and cognitive impairments usually observed in AD. Currently, medications for AD offer moderate symptomatic relief but fail to cure the disease; hence development of effective and safe drugs is urgently needed for AD treatment. In this study, we investigated a Chinese medicine (CM) formulation named NeuroDefend (ND), for reducing amyloid ß (Aß) and tau pathology in transgenic AD mice models. Regular oral administration of ND improved cognitive function and memory in 3XTg-AD and 5XFAD mice. In addition, ND reduced beta-amyloid precursor protein (APP), APP C-terminal fragments (CTF-ß/α), Aß and 4G8 positive Aß burden in 3XTg-AD and 5XFAD mice. Furthermore, ND efficiently reduced the levels of insoluble phospho-tau protein aggregates and AT8 positive phospho tau neuron load in 3XTg-AD mice. Hence, ND could be a promising candidate for the treatment of AD in humans.

A small molecule transcription factor EB activator ameliorates beta-amyloid precursor protein and Tau pathology in Alzheimer's disease models.

Accumulating studies have suggested that targeting transcription factor EB (TFEB), an essential regulator of autophagy-lysosomal pathway (ALP), is promising for the treatment of neurodegenerative disorders, including Alzheimer's disease (AD). However, potent and specific small molecule TFEB activators are not available at present. Previously, we identified a novel TFEB activator named curcumin analog C1 which directly binds to and activates TFEB. In this study, we systematically investigated the efficacy of curcumin analog C1 in three AD animal models that represent beta-amyloid precursor protein (APP) pathology (5xFAD mice), tauopathy (P301S mice) and the APP/Tau combined pathology (3xTg-AD mice). We found that C1 efficiently activated TFEB, enhanced autophagy and lysosomal activity, and reduced APP, APP C-terminal fragments (CTF-ß/α), ß-amyloid peptides and Tau aggregates in these models accompanied by improved synaptic and cognitive function. Knockdown of TFEB and inhibition of lysosomal activity significantly inhibited the effects of C1 on APP and Tau degradation in vitro. In summary, curcumin analog C1 is a potent TFEB activator with promise for the prevention or treatment of AD.

Natural Compounds with Anti-BACE1 Activity as Promising Therapeutic Drugs for Treating Alzheimer's Disease.

Alzheimer's disease is a neurodegenerative disease that leads to irreversible neuronal damage. Senile plaques, composed of amyloid beta peptide, is the principal abnormal characteristic of the disease. Among the factors involved, the secretase enzymes, namely, α secretase, beta-site amyloid precursor protein-cleaving enzyme, ß secretase, and γ secretase, hold consequential importance. Beta-site amyloid precursor protein-cleaving enzyme 1 is considered to be the rate-limiting factor in the production of amyloid beta peptide. Research supporting the concept of inhibition of beta-site amyloid precursor protein-cleaving enzyme activity as one of the effective therapeutic targets in the mitigation of Alzheimer's disease is well accepted. The identification of natural compounds, such as ß-amyloid precursor protein-selective beta-site amyloid precursor protein-cleaving enzyme inhibitors, and the idea of compartmentalisation of the beta-site amyloid precursor protein-cleaving enzyme 1 action have caused a dire need to closely examine the natural compounds and their effectiveness in the disease mitigation. Many natural compounds have been reported to effectively modulate beta-site amyloid precursor protein-cleaving enzyme 1. At lower doses, compounds like 2,2',4'-trihydroxychalcone acid, quercetin, and myricetin have been shown to effectively reduce beta-site amyloid precursor protein-cleaving enzyme 1 activity. The currently used five drugs that are marketed and used for the management of Alzheimer's disease have an increased risk of toxicity and restricted therapeutic efficiency, hence, the search for new anti-Alzheimer's disease drugs is of primary concern. A variety of natural compounds having pure pharmacological moieties showing multitargeting activity and others exhibiting specific beta-site amyloid precursor protein-cleaving enzyme 1 inhibition as discussed below have superior biosafety. Many of these compounds, which are isolated from medicinal herbs and marine flora, have been long used for the treatment of various ailments since ancient times in the Chinese and Ayurvedic medical systems. The aim of this article is to review the available data on the selected natural compounds, giving emphasis to the inhibition of beta-site amyloid precursor protein-cleaving enzyme 1 activity as a mode of Alzheimer's disease treatment.

Recent Updates on Mouse Models for Human Immunodeficiency, Influenza, and Dengue Viral Infections.

Well-developed mouse models are important for understanding the pathogenesis and progression of immunological response to viral infections in humans. Moreover, to test vaccines, anti-viral drugs and therapeutic agents, mouse models are fundamental for preclinical investigations. Human viruses, however, seldom infect mice due to differences in the cellular receptors used by the viruses for entry, as well as in the innate immune responses in mice and humans. In other words, a species barrier exists when using mouse models for investigating human viral infections. Developing transgenic (Tg) mice models expressing the human genes coding for viral entry receptors and knock-out (KO) mice models devoid of components involved in the innate immune response have, to some extent, overcome this barrier. Humanized mouse models are a third approach, developed by engrafting functional human cells and tissues into immunodeficient mice. They are becoming indispensable for analyzing human viral diseases since they nearly recapitulate the human disease. These mouse models also serve to test the efficacy of vaccines and antiviral agents. This review provides an update on the Tg, KO, and humanized mouse models that are used in studies investigating the pathogenesis of three important human-specific viruses, namely human immunodeficiency (HIV) virus 1, influenza, and dengue.

NRBF2 is involved in the autophagic degradation process of APP-CTFs in Alzheimer disease models.

Alzheimer disease (AD) is the most common neurodegenerative disease characterized by the deposition of amyloid plaque in the brain. The autophagy-associated PIK3C3-containing phosphatidylinositol 3-kinase (PtdIns3K) complex has been shown to interfere with APP metabolism and amyloid beta peptide (Aß) homeostasis via poorly understood mechanisms. Here we report that NRBF2 (nuclear receptor binding factor 2), a key component and regulator of the PtdIns3K, is involved in APP-CTFs homeostasis in AD cell models. We found that NRBF2 interacts with APP in vivo and its expression levels are reduced in hippocampus of 5XFAD AD mice; we further demonstrated that NRBF2 overexpression promotes degradation of APP C-terminal fragments (APP-CTFs), and reduces Aß1-40 and Aß1-42 levels in human mutant APP-overexpressing cells. Conversely, APP-CTFs, Aß1-40 and Aß1-42 levels were increased in Nrbf2 knockdown or nrbf2 knockout cells. Furthermore, NRBF2 positively regulates autophagy in neuronal cells and NRBF2-mediated reduction of APP-CTFs levels is autophagy dependent. Importantly, nrbf2 knockout attenuates the recruitment of APP and APP-CTFs into phagophores and the sorting of APP and APP-CTFs into endosomal intralumenal vesicles, which is accompanied by the accumulation of the APP and APP-CTFs into RAB5-positive early endosomes. Collectively, our results reveal the potential connection between NRBF2 and the AD-associated protein APP by showing that NRBF2 plays an important role in regulating degradation of APP-CTFs through modulating autophagy.

A modified formulation of Huanglian-Jie-Du-Tang reduces memory impairments and ß-amyloid plaques in a triple transgenic mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a degenerative disorder typified by progressive deterioration of memory and the appearance of ß-amyloid peptide (Aß)-rich senile plaques. Recently we have identified a novel function of a patented formulation of modified Huanglian-Jie-Tu-Tang (HLJDT-M), a Chinese herbal medicine, in treating AD in in vitro studies (US patent No. 9,375,457). HLJDT-M is a formulation composed of Rhizoma Coptitis, Cortex Phellodendri and Fructus Gardeniae without Radix Scutellariae. Here, we assessed the efficacy of HLJDT-M on a triple transgenic mouse model of AD (3XTg-AD). Oral administration of HLJDT-M ameliorated the cognitive dysfunction of 3XTg-AD mice and lessened the plaque burden. In addition, biochemical assays revealed a significant decrease in levels of detergent-soluble and acid-soluble Aß via decreasing the levels of full length amyloid-ß precursor protein (FL-APP) and C-terminal fragments of APP (CTFs) in brain lysates of HLJDT-M-treated mice. HLJDT-M treatment also significantly reduced the levels of FL-APP and CTFs in N2a/SweAPP cells. In contrast, treatment using the classical formula HLJDT did not reduce the memory impairment of 3XTg-AD mice and, rather, increased the Aß/Fl-APP/CTFs in both animal and cell culture studies. Altogether, our study indicates that HLJDT-M is a promising herbal formulation to prevent and/or cure AD.

Decrease in the Generation of Amyloid-ß Due to Salvianolic Acid B by Modulating BACE1 Activity.

OBJECTIVE: Generation and accumulation of the amyloid-ß (Aß) peptide after proteolytic processing of the full length amyloid precursor protein (FL-APP) by ß-secretase (ß-site APP cleaving enzyme or BACE1) and γ-secretase are the main causal factors of Alzheimer's disease (AD). Thus, inhibition of BACE1, a rate-limiting enzyme in the production of Aß, is an attractive therapeutic approach for the treatment of AD. Recent studies suggest that salvianolic acid B (Sal B) is isolated from the radix of Salvia miltiorrhiza Bunge, a Chinese herbal medicine commonly used for the treatment of cardiovascular, cerebrovascular and liver diseases in China. METHOD: In this study, we discovered that Sal B acted as a BACE1 modulator and reduced the level of secreted Aß in two different Swedish APP (SwedAPP) mutant cell lines. Using N2a-mouse and H4- human neuroglioma cell lines expressing SwedAPP, it was demonstrated that Sal B significantly and dose-dependently decreased the generation of extracellular Aß, soluble APPß (by-product of APP cleaved by BACE1), and intracellular C-terminal fragment ß from APP without influencing α-secretase and γ-secretase activity and the levels of FL-APP. In addition, using protein-docking, we determined the potential conformation of Sal B on BACE1 docking and revealed the interactions of Sal B with the BACE1 catalytic center. RESULTS: The docking provides a feasible explanation for the experimental results, especially in terms of the molecular basis of Sal B's action. Our results indicate that Sal B is a BACE1 inhibitor and, as such, is a promising candidate for the treatment of AD.

A novel curcumin analog binds to and activates TFEB in vitro and in vivo independent of MTOR inhibition.

Autophagy dysfunction is a common feature in neurodegenerative disorders characterized by accumulation of toxic protein aggregates. Increasing evidence has demonstrated that activation of TFEB (transcription factor EB), a master regulator of autophagy and lysosomal biogenesis, can ameliorate neurotoxicity and rescue neurodegeneration in animal models. Currently known TFEB activators are mainly inhibitors of MTOR (mechanistic target of rapamycin [serine/threonine kinase]), which, as a master regulator of cell growth and metabolism, is involved in a wide range of biological functions. Thus, the identification of TFEB modulators acting without inhibiting the MTOR pathway would be preferred and probably less deleterious to cells. In this study, a synthesized curcumin derivative termed C1 is identified as a novel MTOR-independent activator of TFEB. Compound C1 specifically binds to TFEB at the N terminus and promotes TFEB nuclear translocation without inhibiting MTOR activity. By activating TFEB, C1 enhances autophagy and lysosome biogenesis in vitro and in vivo. Collectively, compound C1 is an orally effective activator of TFEB and is a potential therapeutic agent for the treatment of neurodegenerative diseases.