Induction of autophagy by a novel small molecule improves aβ pathology and ameliorates cognitive deficits

Rescue of ApoE4-related lysosomal autophagic failure in Alzheimer's disease by targeted small molecules

Homozygosity for the ε4 allele of APOE increases the odds of developing Alzheimer's by 12 to 15 times relative to the most common ε3;ε3 genotype, and its association with higher plaque loads comports with evidence that APOEε4 compromises autophagy. The ApoE4 protein specifically binds a cis element ("CLEAR") in the promoters of several autophagy genes to block their transcription. We used a multifaceted approach to identify a druggable site in ApoE4, and virtual screening of lead-like compounds identified small molecules that specifically bind to this site to impede ApoE4::DNA binding. We validated these molecules both in vitro and in vivo with models expressing ApoE4, including ApoE4 targeted-replacement mice. One compound was able to significantly restore transcription of several autophagy genes and protected against amyloid-like aggregation in a C. elegans AD model. Together, these findings provide proof-of-principle evidence for pharmacological remediation of lysosomal autophagy by ApoE4 via ApoE4-targeted lead molecules that represent a novel tack on neurodegenerative disorders.

Discovery of a Small-Molecule Modulator of the Autophagy-Lysosome Pathway That Targets Lamin A/C and LAMP1, Induces Autophagic Flux, and Affects Lysosome Positioning in Neurons

Autophagy is a major catabolic degradation and recycling process that maintains homeostasis in cells and is especially important in postmitotic neurons. We implemented a high-content phenotypic assay to discover small molecules that promote autophagic flux and completed target identification and validation studies to identify protein targets that modulate the autophagy pathway and promote neuronal health and survival. Efficient syntheses of the prioritized compounds were developed to readily access analogues of the initial hits, enabling initial structure-activity relationship studies to improve potency and preparation of a biotin-tagged pulldown probe that retains activity. This probe facilitated target identification and validation studies through pulldown and competition experiments using both an unbiased proteomics approach and western blotting to reveal Lamin A/C and LAMP1 as the protein targets of compound RH1115. Evaluation of RH1115 in neurons revealed that this compound induces changes to LAMP1 vesicle properties and alters lysosome positioning. Dysfunction of the autophagy-lysosome pathway has been implicated in a variety of neurodegenerative diseases, including Alzheimer's disease, highlighting the value of new strategies for therapeutic modulation and the importance of small-molecule probes to facilitate the study of autophagy regulation in cultured neurons and in vivo.

A long-term high-fat diet influences brain damage and is linked to the activation of HIF-1α/AMPK/mTOR/p70S6K signalling

High-fat diets (HFDs) are related to the incidence of obesity and diabetes, but the effect of high-fat diet-induced brain damage remains to be clarified. In our study, we found that 24 weeks of a HFD effectively induced obesity and a change in fur color in mice. In addition, the mice also exhibited deficits in learning and memory. We further found that autophagic flux was impaired in mice after HFD feeding. Hypoxia-inducible factor 1α (HIF-1α) expression was significantly increased in HFD-fed mice, and HFD feeding inhibited adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and induced mechanistic target of rapamycin (mTOR) phosphorylation and p70S6K expression. Treatment of HFD-induced BV2 cell model with palmitic acid (PA) was used to further verify a similar result. We concluded that improving tissue hypoxia or enhancing autophagy through the AMPK/mTOR/p70S6K pathway may be a relevant strategy for improving obesity- and ageing-related disorders.

Pharmacological modulation of autophagy for Alzheimer’s disease therapy: Opportunities and obstacles

Alzheimer's disease (AD) is a prevalent and deleterious neurodegenerative disorder characterized by an irreversible and progressive impairment of cognitive abilities as well as the formation of amyloid β (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain. By far, the precise mechanisms of AD are not fully understood and no interventions are available to effectively slow down progression of the disease. Autophagy is a conserved degradation pathway that is crucial to maintain cellular homeostasis by targeting damaged organelles, pathogens, and disease-prone protein aggregates to lysosome for degradation. Emerging evidence suggests dysfunctional autophagy clearance pathway as a potential cellular mechanism underlying the pathogenesis of AD in affected neurons. Here we summarize the current evidence for autophagy dysfunction in the pathophysiology of AD and discuss the role of autophagy in the regulation of AD-related protein degradation and neuroinflammation in neurons and glial cells. Finally, we review the autophagy modulators reported in the treatment of AD models and discuss the obstacles and opportunities for potential clinical application of the novel autophagy activators for AD therapy.

Exploring the Role of Autophagy Dysfunction in Neurodegenerative Disorders

Autophagy is a catabolic pathway by which misfolded proteins or damaged organelles are engulfed by autophagosomes and then transported to lysosomes for degradation. Recently, a great improvement has been done to explain the molecular mechanisms and roles of autophagy in several important cellular metabolic processes. Besides being a vital clearance pathway or a cell survival pathway in response to different stresses, autophagy dysfunction, either upregulated or down-regulated, has been suggested to be linked with numerous neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, Huntington's disease, and Amyotrophic lateral sclerosis. Impairment at different stages of autophagy results in the formation of large protein aggregates and damaged organelles, which leads to the onset and progression of different neurodegenerative disorders. This article elucidates the recent progress about the role of autophagy in neurodegenerative disorders and explains how autophagy dysfunction is linked with the pathogenesis of such disorders as well as the novel potential autophagy-associated therapies for treating them.

Is Alzheimer's disease an inflammasomopathy?

Alzheimer's disease (AD) is the most common form of dementia in the elderly and, despite the tremendous efforts researchers have put into AD research, there are no effective options for prevention and treatment of the disease. The best way to reach this goal is to clarify the mechanisms involved in the onset and progression of AD. In the last few years the views about the drivers of AD have been changing and nowadays it is believed that neuroinflammation takes center stage in disease pathogenesis. Herein, we provide an overview about the role of neuroinflammation in AD describing the role of microglia and astroglia is this process. Then, we will debate the NLRP3 inflammasome putting the focus on its activation through the canonical, non-canonical and alternative pathways and the triggers involved herein namely endoplasmic reticulum stress, mitochondrial dysfunction, reactive oxygen species and amyloid β peptide. Data supporting the hypothesis that inflammasome-mediated peripheral inflammation may contribute to AD pathology will be presented. Finally, a brief discussion about the therapeutic potential of NLRP3 inflammasome modulation is also provided.

Autophagy Modulation as a Treatment of Amyloid Diseases

Amyloids are fibrous proteins aggregated into toxic forms that are implicated in several chronic disorders. More than 30 diseases show deposition of fibrous amyloid proteins associated with cell loss and degeneration in the affected tissues. Evidence demonstrates that amyloid diseases result from protein aggregation or impaired amyloid clearance, but the connection between amyloid accumulation and tissue degeneration is not clear. Common examples of amyloid diseases are Alzheimer's disease (AD), Parkinson's disease (PD) and tauopathies, which are the most common forms of neurodegenerative diseases, as well as polyglutamine disorders and certain peripheral metabolic diseases. In these diseases, increased accumulation of toxic amyloid proteins is suspected to be one of the main causative factors in the disease pathogenesis. It is therefore important to more clearly understand how these toxic amyloid proteins accumulate as this will aide in the development of more effective preventive and therapeutic strategies. Protein homeostasis, or proteostasis, is maintained by multiple cellular pathways-including protein synthesis, quality control, and clearance-which are collectively responsible for preventing protein misfolding or aggregation. Modulating protein degradation is a very complex but attractive treatment strategy used to remove amyloid and improve cell survival. This review will focus on autophagy, an important clearance pathway of amyloid proteins, and strategies for using it as a potential therapeutic target for amyloid diseases. The physiological role of autophagy in cells, pathways for its modulation, its connection with apoptosis, cell models and caveats in developing autophagy as a treatment and as a biomarker is discussed.

Recent progress in the role of autophagy in neurological diseases

Autophagy (here refers to macroautophagy) is a catabolic pathway by which large protein aggregates and damaged organelles are first sequestered into a double-membraned structure called autophago-some and then delivered to lysosome for destruction. Recently, tremen-dous progress has been made to elucidate the molecular mechanism and functions of this essential cellular metabolic process. In addition to being either a rubbish clearing system or a cellular surviving program in response to different stresses, autophagy plays important roles in a large number of pathophysiological conditions, such as cancer, diabetes, and especially neurodegenerative disorders. Here we review recent progress in the role of autophagy in neurological diseases and discuss how dysregulation of autophagy initiation, autophagosome formation, maturation, and/or au-tophagosome-lysosomal fusion step contributes to the pathogenesis of these disorders in the nervous system.

p62-Keap1-NRF2-ARE Pathway: A Contentious Player for Selective Targeting of Autophagy, Oxidative Stress and Mitochondrial Dysfunction in Prion Diseases

Prion diseases are a group of fatal and debilitating neurodegenerative diseases affecting humans and animal species. The conversion of a non-pathogenic normal cellular protein (PrP^c) into an abnormal infectious, protease-resistant, pathogenic form prion protein scrapie (PrP^Sc), is considered the etiology of these diseases. PrP^Sc accumulates in the affected individual's brain in the form of extracellular plaques. The molecular pathways leading to neuronal cell death in prion diseases are still unclear. The free radical damage, oxidative stress and mitochondrial dysfunction play a key role in the pathogenesis of the various neurodegenerative disorders including prion diseases. The brain is very sensitive to changes in the redox status. It has been demonstrated that PrP^c behaves as an antioxidant, while the neurotoxic prion peptide PrP^Sc increases hydrogen peroxide toxicity in the neuronal cultures leading to mitochondrial dysfunction and cell death. The nuclear factor erythroid 2-related factor 2 (NRF2) is an oxidative responsive pathway and a guardian of lifespan, which protect the cells from free radical stress-mediated cell death. The reduced glutathione, a major small molecule antioxidant present in all mammalian cells, and produced by several downstream target genes of NRF2, counterbalances the mitochondrial reactive oxygen species (ROS) production. In recent years, it has emerged that the ubiquitin-binding protein, p62-mediated induction of autophagy, is crucial for NRF2 activation and elimination of mitochondrial dysfunction and oxidative stress. The current review article, focuses on the role of NRF2 pathway in prion diseases to mitigate the disease progression.

p62-Keap1-NRF2-ARE Pathway: A Contentious Player for Selective Targeting of Autophagy, Oxidative Stress and Mitochondrial Dysfunction in Prion Diseases

Prion diseases are a group of fatal and debilitating neurodegenerative diseases affecting humans and animal species. The conversion of a non-pathogenic normal cellular protein (PrP^c) into an abnormal infectious, protease-resistant, pathogenic form prion protein scrapie (PrP^Sc), is considered the etiology of these diseases. PrP^Sc accumulates in the affected individual’s brain in the form of extracellular plaques. The molecular pathways leading to neuronal cell death in prion diseases are still unclear. The free radical damage, oxidative stress and mitochondrial dysfunction play a key role in the pathogenesis of the various neurodegenerative disorders including prion diseases. The brain is very sensitive to changes in the redox status. It has been demonstrated that PrP^c behaves as an antioxidant, while the neurotoxic prion peptide PrP^Sc increases hydrogen peroxide toxicity in the neuronal cultures leading to mitochondrial dysfunction and cell death. The nuclear factor erythroid 2-related factor 2 (NRF2) is an oxidative responsive pathway and a guardian of lifespan, which protect the cells from free radical stress-mediated cell death. The reduced glutathione, a major small molecule antioxidant present in all mammalian cells, and produced by several downstream target genes of NRF2, counterbalances the mitochondrial reactive oxygen species (ROS) production. In recent years, it has emerged that the ubiquitin-binding protein, p62-mediated induction of autophagy, is crucial for NRF2 activation and elimination of mitochondrial dysfunction and oxidative stress. The current review article, focuses on the role of NRF2 pathway in prion diseases to mitigate the disease progression.

Autophagy in Age-Associated Neurodegeneration

The elimination of abnormal and dysfunctional cellular constituents is an essential prerequisite for nerve cells to maintain their homeostasis and proper function. This is mainly achieved through autophagy, a process that eliminates abnormal and dysfunctional cellular components, including misfolded proteins and damaged organelles. Several studies suggest that age-related decline of autophagy impedes neuronal homeostasis and, subsequently, leads to the progression of neurodegenerative disorders due to the accumulation of toxic protein aggregates in neurons. Here, we discuss the involvement of autophagy perturbation in neurodegeneration and present evidence indicating that upregulation of autophagy holds potential for the development of therapeutic interventions towards confronting neurodegenerative diseases in humans.

Autophagy and Alzheimer's Disease: From Molecular Mechanisms to Therapeutic Implications

Alzheimer’s disease (AD) is the most common cause of progressive dementia in the elderly. It is characterized by a progressive and irreversible loss of cognitive abilities and formation of senile plaques, composed mainly of amyloid β (Aβ), and neurofibrillary tangles (NFTs), composed of tau protein, in the hippocampus and cortex of afflicted humans. In brains of AD patients the metabolism of Aβ is dysregulated, which leads to the accumulation and aggregation of Aβ. Metabolism of Aβ and tau proteins is crucially influenced by autophagy. Autophagy is a lysosome-dependent, homeostatic process, in which organelles and proteins are degraded and recycled into energy. Thus, dysfunction of autophagy is suggested to lead to the accretion of noxious proteins in the AD brain. In the present review, we describe the process of autophagy and its importance in AD. Additionally, we discuss mechanisms and genes linking autophagy and AD, i.e., the mTOR pathway, neuroinflammation, endocannabinoid system, ATG7, BCL2, BECN1, CDK5, CLU, CTSD, FOXO1, GFAP, ITPR1, MAPT, PSEN1, SNCA, UBQLN1, and UCHL1. We also present pharmacological agents acting via modulation of autophagy that may show promise in AD therapy. This review updates our knowledge on autophagy mechanisms proposing novel therapeutic targets for the treatment of AD.

Autophagy in neurodegenerative diseases: pathogenesis and therapy

The most prevalent pathological features of many neurodegenerative diseases are the aggregation of misfolded proteins and the loss of certain neuronal populations. Autophagy, as major intracellular machinery for degrading aggregated proteins and damaged organelles, has been reported to be involved in the occurrence of pathological changes in many neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis. In this review, we summarize most recent research progress in this topic and provide a new perspective regarding autophagy regulation on the pathogenesis of neurodegenerative diseases. Finally, we discuss the signaling molecules in autophagy-related pathways as therapeutic targets for the treatment of these diseases.

Assessment of Autophagy in Neurons and Brain Tissue

Autophagy is a complex process that controls the transport of cytoplasmic components into lysosomes for degradation. This highly conserved proteolytic system involves dynamic and complex processes, using similar molecular elements and machinery from yeast to humans. Moreover, autophagic dysfunction may contribute to a broad spectrum of mammalian diseases. Indeed, in adult tissues, where the capacity for regeneration or cell division is low or absent (e.g., in the mammalian brain), the accumulation of proteins/peptides that would otherwise be recycled or destroyed may have pathological implications. Indeed, such changes are hallmarks of pathologies, like Alzheimer’s, Prion or Parkinson’s disease, known as proteinopathies. However, it is still unclear whether such dysfunction is a cause or an effect in these conditions. One advantage when analysing autophagy in the mammalian brain is that almost all the markers described in different cell lineages and systems appear to be present in the brain, and even in neurons. By contrast, the mixture of cell types present in the brain and the differentiation stage of such neurons, when compared with neurons in culture, make translating basic research to the clinic less straightforward. Thus, the purpose of this review is to describe and discuss the methods available to monitor autophagy in neurons and in the mammalian brain, a process that is not yet fully understood, focusing primarily on mammalian macroautophagy. We will describe some general features of neuronal autophagy that point to our focus on neuropathologies in which macroautophagy may be altered. Indeed, we centre this review around the hypothesis that enhanced autophagy may be able to provide therapeutic benefits in some brain pathologies, like Alzheimer’s disease, considering this pathology as one of the most prevalent proteinopathies.

Evaluating the Effectiveness of GTM-1, Rapamycin, and Carbamazepine on Autophagy and Alzheimer Disease

Background

This study was proposed to compare the efficacy and safety of GTM-1, Rapamycin (Rap), and Carbamazepine (CBZ) in managing Alzheimer disease (AD). The impact of the above mentioned therapeutic drugs on autophagy was also investigated in our study.

Material/Methods

Firstly, 3×Tg AD mice were randomly allocated into 4 groups (each group with 10 mice), in which AD mice were separately treated with dimethylsulfoxide (DMSO, vehicle group), GTM-1 (6 mg/kg), Rap (1 mg/kg), and CBZ (100 mg/kg). Then spatial memory and learning ability of mice was tested using the Morris water maze. Routine blood tests were performed to evaluate the toxicity of these drugs. Amyloid-β42 (Aβ42) concentration was detected by ELISA and immunohistochemistry. Proteins related to autophagy were detected by Western blot.

Results

GTM-1, Rap, and CBZ significantly improved the spatial memory of 3×Tg AD mice compared to that in the vehicle group (all P<0.05). Moreover, this study revealed that CBZ dosage was related to toxicity in mice. All of the above drugs significantly increased the expression of LC3-II and reduced Aβ42 levels in hippocampi of 3×Tg AD mice (all P<0.05). On the other hand, neither GTM-1 nor CBZ had significant influence on the expression of proteins on the mTOR pathway.

Conclusions

GTM-1 can alleviate the AD syndrome by activating autophagy in a manner that is dependent on the mTOR pathway and it therefore can be considered as an alternative to Rap.

Protective effects of GTM-1 on endoplasmic reticulum stress induced by thapsgargin in rat neurons

GTM-1 is a drug that reverses Alzheimer's Disease (AD) development specifically induced by thapsgargin (TG) and endoplasmic reticulum (ER) has been reported to be a pilot process that leads to AD formation. It is speculated that GTM-1 could also prohibit TG-induced ER stress. In this study, we utilized immuno-fluorescence to identify morphological changes in nucleus and transmission electron microscopy was used to observe neuronal ultra-structures. Moreover, expressions of GRP78, CHOP, Bcl-2 and cytochrome c were assessed using immuno-blotting, while calcium concentration was detected by fluorescence spectrometer. As suggested by the above cellular experiments, neuronal ultrastructures were damaged by the treatment of TG, while this damaging trend was reversed when neurons were simultaneously treated with both TG and GTM-1. Besides that, certain marker proteins of ER stress (e.g. GRP78, CHOP, and cytochrome c) and calcium concentrations in neurons were significantly increased when TG was applied, while these levels were reduced to normal conditions when GTM-1 was added in the treatment. In conclusion, GTM-1 restrained the ongoing of ER stress that was induced by TG.

TFEB Participates in the Aβ-Induced Pathogenesis of Alzheimer's Disease by Regulating the Autophagy-Lysosome Pathway

To investigate whether transcriptional factor EB (TFEB) participates in amyloid-β(1-42) (Aβ(1-42))-induced pathogenesis of Alzheimer's disease (AD) and its underlying mechanisms. Three-month-old and 8-month-old transgenic APP/PS1 AD mice and age-matched wild mice were used in this study. We found that the 8-month-old AD animals presented significantly higher deposition of Aβ(1-42) and expression of TFEB and its targeted proteins, such as LAMP-1 and cathepsin D, and autophagy-associated LC3-II and p62 in brain tissues than in others. In an in vitro study, TFEB overexpression rescued autophagic flux that blocked by Aβ(1-42) and the degradation of the absorbed Aβ(1-42), relieved Aβ(1-42)-mediated induction of overloaded autophagy. In addition, TFEB overexpression enhanced cathepsin D expression and activity, restored Aβ(1-42)-disturbed acid environment of lysosome, and promoted the fusion of autophagosomes with lysosomes. Furthermore, TFEB upregulation reduced Aβ(1-42)-induced production of malondialdehyde, oxidative carbonyl proteins, and reactive oxygen species (ROS) and cell apoptosis mainly dependent on the removal of Aβ(1-42) by the autophagy-lysosome pathway. TFEB overexpression alleviated AD progression by reducing Aβ accumulation through regulating the autophagy-lysosome pathway and reducing Aβ-induced ROS production and cell apoptosis.

Cilostazol Upregulates Autophagy via SIRT1 Activation: Reducing Amyloid-β Peptide and APP-CTFβ Levels in Neuronal Cells

Autophagy is a vital pathway for the removal of β-amyloid peptide (Aβ) and the aggregated proteins that cause Alzheimer’s disease (AD). We previously found that cilostazol induced SIRT1 expression and its activity in neuronal cells, and thus, we hypothesized that cilostazol might stimulate clearances of Aβ and C-terminal APP fragment β subunit (APP-CTFβ) by up-regulating autophagy.When N2a cells were exposed to soluble Aβ1–42, protein levels of beclin-1, autophagy-related protein5 (Atg5), and SIRT1 decreased significantly. Pretreatment with cilostazol (10–30 μM) or resveratrol (20 μM) prevented these Aβ1–42 evoked suppressions. LC3-II (a marker of mammalian autophagy) levels were significantly increased by cilostazol, and this increase was reduced by 3-methyladenine. To evoke endogenous Aβ overproduction, N2aSwe cells (N2a cells stably expressing human APP containing the Swedish mutation) were cultured in medium with or without tetracycline (Tet⁺ for 48 h and then placed in Tet^- condition). Aβ and APP-CTFβ expressions were increased after 12~24 h in Tet^- condition, and these increased expressions were significantly reduced by pretreating cilostazol. Cilostazol-induced reductions in the expressions of Aβ and APP-CTFβ were blocked by bafilomycin A1 (a blocker of autophagosome to lysosome fusion). After knockdown of the SIRT1 gene (to ~40% in SIRT1 protein), cilostazol failed to elevate the expressions of beclin-1, Atg5, and LC3-II, indicating that cilostazol increases these expressions by up-regulating SIRT1. Further, decreased cell viability induced by Aβ was prevented by cilostazol, and this inhibition was reversed by 3-methyladenine, indicating that the protective effect of cilostazol against Aβ induced neurotoxicity is, in part, ascribable to the induction of autophagy. In conclusion, cilostazol modulates autophagy by increasing the activation of SIRT1, and thereby enhances Aβ clearance and increases cell viability.

Autophagic activity in neuronal cell death

As post-mitotic cells with great energy demands, neurons depend upon the homeostatic and waste-recycling functions provided by autophagy. In addition, autophagy also promotes survival during periods of harsh stress and targets aggregate-prone proteins associated with neurodegeneration for degradation. Despite this, autophagy has also been controversially described as a mechanism of programmed cell death. Instances of autophagic cell death are typically associated with elevated numbers of cytoplasmic autophagosomes, which have been assumed to lead to excessive degradation of cellular components. Due to the high activity and reliance on autophagy in neurons, these cells may be particularly susceptible to autophagic death. In this review, we summarize and assess current evidence in support of autophagic cell death in neurons, as well as how the dysregulation of autophagy commonly seen in neurodegeneration can contribute to neuron loss. From here, we discuss potential treatment strategies relevant to such cell-death pathways.

Loss of endophilin-B1 exacerbates Alzheimer's disease pathology

Endophilin-B1, also known as Bax-interacting factor 1 (Bif-1, and encoded by SH3GLB1), is a multifunctional protein involved in apoptosis, autophagy and mitochondrial function. We recently described a unique neuroprotective role for neuron-specific alternatively spliced isoforms of endophilin-B1. To examine whether endophilin-B1-mediated neuroprotection could be a novel therapeutic target for Alzheimer's disease we used a double mutant amyloid precursor protein and presenilin 1 (APPswe/PSEN1dE9) mouse model of Alzheimer's disease and observed that expression of neuron-specific endophilin-B1 isoforms declined with disease progression. To determine if this reduction in endophilin-B1 has a functional role in Alzheimer's disease pathogenesis, we crossed endophilin-B1(-/-) mice with APPswe/PSEN1dE9 mice. Deletion of endophilin-B1 accelerated disease onset and progression in 6-month-old APPswe/PSEN1dE9/endophilin-B1(-/-) mice, which showed more plaques, astrogliosis, synaptic degeneration, cognitive impairment and mortality than APPswe/PSEN1dE9 mice. In mouse primary cortical neuron cultures, overexpression of neuron-specific endophilin-B1 isoforms protected against amyloid-β-induced apoptosis and mitochondrial dysfunction. Additionally, protein and mRNA levels of neuron-specific endophilin-B1 isoforms were also selectively decreased in the cerebral cortex and in the synaptic compartment of patients with Alzheimer's disease. Flow sorting of synaptosomes from patients with Alzheimer's disease demonstrated a negative correlation between amyloid-β and endophilin-B1 levels. The importance of endophilin-B1 in neuronal function was further underscored by the development of synaptic degeneration and cognitive and motor impairment in endophilin-B1(-/-) mice by 12 months. Our findings suggest that endophilin-B1 is a key mediator of a feed-forward mechanism of Alzheimer's disease pathogenesis where amyloid-β reduces neuron-specific endophilin-B1, which in turn enhances amyloid-β accumulation and neuronal vulnerability to stress.

Autophagy and neurodegeneration

Most neurodegenerative diseases that afflict humans are associated with the intracytoplasmic deposition of aggregate-prone proteins in neurons. Autophagy is a powerful process for removing such proteins. In this Review, we consider how certain neurodegenerative diseases may be associated with impaired autophagy and how this may affect pathology. We also discuss how autophagy induction may be a plausible therapeutic strategy for some conditions and review studies in various models that support this hypothesis. Finally, we briefly describe some of the signaling pathways that may be amenable to therapeutic targeting for these goals.

Epigallocatechin-3-gallate attenuates impairment of learning and memory in chronic unpredictable mild stress-treated rats by restoring hippocampal autophagic flux

Epigallocatechin gallate (EGCG) is a major polyphenol in green tea with beneficial effects on the impairment in learning and memory. Autophagy is a cellular process that protects neurons from stressful conditions. The present study was designed to investigate whether EGCG can rescue chronic unpredictable mild stress (CUMS)-induced cognitive impairment in rats and whether its protective effect involves improvement of autophagic flux. As expected, our results showed that CUMS significantly impaired memory performance and inhibited autophagic flux as indicated by elevated LC3-II and p62 protein levels. At the same time, we observed an increased neuronal loss and activated mammalian target of rapamycin (mTOR)/p70 ribosomal protein S6 kinase (p70S6k) signaling in the CA1 regions. Interestingly, chronic treatment with EGCG (25 mg/kg, i.p.) significantly improved those behavioral alterations, attenuated histopathological abnormalities in hippocampal CA1 regions, reduced amyloid beta1-42 (Aβ1-42) levels, and restored autophagic flux. However, blocking autophagic flux with chloroquine, an inhibitor of autophagic flux, reversed these effects of EGCG. Taken together, these findings suggest that the impaired autophagy in CA1 regions of CUMS rats may contribute to learning and memory impairment. Therefore, we conclude that EGCG attenuation of CUMS-induced learning and memory impairment may be through rescuing autophagic flux.

Pharmacogenomics of Alzheimer's disease: novel therapeutic strategies for drug development

Alzheimer's disease (AD) is a major problem of health and disability, with a relevant economic impact on our society. Despite important advances in pathogenesis, diagnosis, and treatment, its primary causes still remain elusive, accurate biomarkers are not well characterized, and the available pharmacological treatments are not cost-effective. As a complex disorder, AD is a polygenic and multifactorial clinical entity in which hundreds of defective genes distributed across the human genome may contribute to its pathogenesis. Diverse environmental factors, cerebrovascular dysfunction, and epigenetic phenomena, together with structural and functional genomic dysfunctions, lead to amyloid deposition, neurofibrillary tangle formation, and premature neuronal death, the major neuropathological hallmarks of AD. Future perspectives for the global management of AD predict that genomics and proteomics may help in the search for reliable biomarkers. In practical terms, the therapeutic response to conventional drugs (cholinesterase inhibitors, multifactorial strategies) is genotype-specific. Genomic factors potentially involved in AD pharmacogenomics include at least five categories of gene clusters: (1) genes associated with disease pathogenesis; (2) genes associated with the mechanism of action of drugs; (3) genes associated with drug metabolism (phase I and II reactions); (4) genes associated with drug transporters; and (5) pleiotropic genes involved in multifaceted cascades and metabolic reactions. The implementation of pharmacogenomic strategies will contribute to optimize drug development and therapeutics in AD and related disorders.