Bioenergetic and inflammatory systemic phenotypes in Alzheimer’s disease APOE ε4‐carriers

We examined the impact of an APOE ε4 genotype on Alzheimer''s disease (AD) subject platelet and lymphocyte metabolism. Mean platelet mitochondrial cytochrome oxidase Vmax activity was lower in APOE ε4 carriers and lymphocyte Annexin V, a marker of apoptosis, was significantly higher. Proteins that mediate mitophagy and energy sensing were higher in APOE ε4 lymphocytes which could represent compensatory changes and recapitulate phenomena observed in post‐mortem AD brains. Analysis of the lipid synthesis pathway found higher AceCSI, ATP CL, and phosphorylated ACC levels in APOE ε4 lymphocytes. Lymphocyte ACC changes were also observed in post‐mortem brain tissue. Lymphocyte RNAseq showed lower APOE ε4 carrier sphingolipid Transporter 3 (SPNS3) and integrin Subunit Alpha 1 (ITGA1) expression. RNAseq pathway analysis revealed APOE ε4 alleles activated inflammatory pathways and modulated bioenergetic signaling. These findings support a relationship between APOE genotype and bioenergetic pathways and indicate platelets and lymphocytes from APOE ε4 carriers exist in a state of bioenergetic stress. Neither medication use nor brain‐localized AD histopathology can account for these findings, which define an APOE ε4‐determined molecular and systemic phenotype that informs AD etiology.     

基于CRISPR/Cas9系统和增强ssODN重组建立tau-V337M小鼠模型

利用CRISPR/Cas9基因编辑技术建立tau-V337M突变的阿尔茨海默病(Alzheimer’s disease,AD)小鼠模型。通过设计和体外合成单向导RNAs(single guide RNAs,sgRNA)及单链寡核苷酸(single-stranded oligonucleotides,ssODN),将sgRNA、Cas9蛋白、ssODN注射到小鼠受精卵内,利用DNA切割和重组产生突变。为了提高重组效率,又在注射时添加Rad51蛋白。使用自然交配的雌鼠作为受体,将2细胞期的编辑胚胎进行单侧输卵管移植。研究发现通过添加Rad51蛋白可以获得较高的突变效率,在F0小鼠中获得了tau-V337M小鼠并进行扩繁,F0代tau-V337M小鼠可以将突变遗传给F1代。综上所述,本研究利用Cas9、ssODN和Rad51成功建立了首个tau-V337M基因位点突变的小鼠模型,为AD的研究和点突变模型制作提供了模型和方法基础。     

Alzheimer’s disease associated AKAP9 I2558M mutation alters posttranslational modification and interactome of tau and cellular functions in CRISPR‐edited human neuronal cells

Alzheimer''s disease (AD) is a pervasive neurodegeneration disease with high heritability. In this study, we employed CRISPR‐Cas9‐engineered technology to investigate the effects of a rare mutation (rs144662445) in the A kinase anchoring protein 9 (AKAP9) gene, which is associated with AD in African Americans (AA), on tau pathology and the tau interactome in SH‐SY5Y P301L neuron‐like cells. The mutation significantly increased the level of phosphorylated tau, specifically at the site Ser396/Ser404. Moreover, analyses of the tau interactome measured by affinity purification‐mass spectrometry revealed that differentially expressed tau‐interacting proteins in AKAP9 mutant cells were associated with RNA translation, RNA localization and oxidative activity, recapitulating the tau interactome signature previously reported with human AD brain samples. Importantly, these results were further validated by functional studies showing a significant reduction in protein synthesis activity and excessive oxidative stress in AKAP9 mutant compared with wild type cells in a tau‐dependent manner, which are mirrored with pathological phenotype frequently seen in AD. Our results demonstrated specific effects of rs14462445 on mis‐processing of tau and suggest a potential role of AKAP9 in AD pathogenesis.     

Impact of nanoparticles on amyloid β-induced Alzheimer’s disease,tuberculosis, leprosy and cancer: a systematic review

Nanotechnology is an interdisciplinary domain of science, technology and engineering that deals with nano-sized materials/particles. Usually, the size of nanoparticles lies between 1 and 100 nm. Due to their small size and large surface area-to-volume ratio, nanoparticles exhibit high reactivity, greater stability and adsorption capacity. These important physicochemical properties attract scientific community to utilize them in biomedical field. Various types of nanoparticles (inorganic and organic) have broad applications in medical field ranging from imaging to gene therapy. These are also effective drug carriers. In recent times, nanoparticles are utilized to circumvent different treatment limitations. For example, the ability of nanoparticles to cross the blood−brain barrier and having a certain degree of specificity towards amyloid deposits makes themselves important candidates for the treatment of Alzheimer’s disease. Furthermore, nanotechnology has been used extensively to overcome several pertinent issues like drug-resistance phenomenon, side effects of conventional drugs and targeted drug delivery issue in leprosy, tuberculosis and cancer. Thus, in this review, the application of different nanoparticles for the treatment of these four important diseases (Alzheimer’s disease, tuberculosis, leprosy and cancer) as well as for the effective delivery of drugs used in these diseases has been presented systematically. Although nanoformulations have many advantages over traditional therapeutics for treating these diseases, nanotoxicity is a major concern that has been discussed subsequently. Lastly, we have presented the promising future prospective of nanoparticles as alternative therapeutics. In that section, we have discussed about the futuristic approach(es) that could provide promising candidate(s) for the treatment of these four diseases.     

GanDouLing promotes proliferation and differentiation of neural stem cells in the mouse model of Wilson’s disease

Wilson’s disease (WD) is an autosomal recessive disease caused by mutation of the ATPase copper transporting β (ATP7B) gene, resulting in abnormal copper metabolism. We aimed to investigate the protective effect of GanDouLing (GDL) on neural stem cell (NSC) function in a mouse model of WD. NSCs were treated with different concentrations of GDL alone or in combination with penicillamine, following which we evaluated cellular growth, apoptosis, and differentiation. Nuclear factor E2-related factor 2 (Nrf2) pathway and NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation were analyzed via Western blotting. Treatment with GDL alone or in combination with penicillamine significantly increased proliferation and inhibited apoptosis of NSCs in a dose-dependent manner. In addition, GDL treatment remarkably promoted differentiation of NSCs. Consistently, levels of class III β-tubulin (Tuj1) and microtubule-associated protein 2 (MAP2) were significantly elevated, whereas glial fibrillary acidic protein (GFAP) levels were obviously suppressed in the presence of GDL or penicillamine. In vivo assays confirmed that GDL increased the ratio of Ki67⁺, Tuj1⁺, and MAP2⁺ cells and suppressed apoptosis in the hippocampal region in WD mice. Behavioral assays revealed that both GDL and penicillamine improved memory ability in WD models. Mechanistically, GDL treatment led to activation of Nrf2 signaling and suppression of the NLRP3 inflammasome in WD mice. Notably, inhibition of Nrf2 signaling reversed the protective effects of GDL on hippocampal NSCs. Collectively, these findings demonstrate that GDL exerts a protective effect on NSCs and promotes neurogenesis by targeting Nrf2 signaling and the NLRP3 inflammasome in WD.     

Olfactory neuropathology in Alzheimer’s disease: a sign of ongoing neurodegeneration

Olfactory neuropathology is a cause of olfactory loss in Alzheimer’s disease (AD). Olfactory dysfunction is also associated with memory and cognitive dysfunction and is an incidental finding of AD dementia. Here we review neuropathological research on the olfactory system in AD, considering both structural and functional evidence. Experimental and clinical findings identify olfactory dysfunction as an early indicator of AD. In keeping with this, amyloid-β production and neuroinflammation are related to underlying causes of impaired olfaction. Notably, physiological features of the spatial map in the olfactory system suggest the evidence of ongoing neurodegeneration. Our aim in this review is to examine olfactory pathology findings essential to identifying mechanisms of olfactory dysfunction in the development of AD in hopes of supporting investigations leading towards revealing potential diagnostic methods and causes of early pathogenesis in the olfactory system.     

TRPV1 activation alleviates cognitive and synaptic plasticity impairments through inhibiting AMPAR endocytosis in APP23/PS45 mouse model of Alzheimer’s disease

Alzheimer's disease (AD) is one of the most common causes of neurodegenerative diseases in the elderly. The accumulation of amyloid‐β (Aβ) peptides is one of the pathological hallmarks of AD and leads to the impairments of synaptic plasticity and cognitive function. The transient receptor potential vanilloid 1 (TRPV1), a nonselective cation channel, is involved in synaptic plasticity and memory. However, the role of TRPV1 in AD pathogenesis remains largely elusive. Here, we reported that the expression of TRPV1 was decreased in the brain of APP23/PS45 double transgenic AD model mice. Genetic upregulation of TRPV1 by adeno‐associated virus (AAV) inhibited the APP processing and Aβ deposition in AD model mice. Meanwhile, upregulation of TRPV1 ameliorated the deficits of hippocampal CA1 long‐term potentiation (LTP) and spatial learning and memory through inhibiting GluA2‐containing α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptor (AMPAR) endocytosis. Furthermore, pharmacological activation of TRPV1 by capsaicin (1 mg/kg, i.p.), an agonist of TRPV1, dramatically reversed the impairments of hippocampal CA1 LTP and spatial learning and memory in AD model mice. Taken together, these results indicate that TRPV1 activation effectively ameliorates cognitive and synaptic functions through inhibiting AMPAR endocytosis in AD model mice and could be a novel molecule for AD treatment.     

α‐synuclein suppresses microglial autophagy and promotes neurodegeneration in a mouse model of Parkinson’s disease

The cell‐to‐cell transfer of α‐synuclein (α‐Syn) greatly contributes to Parkinson''s disease (PD) pathogenesis and underlies the spread of α‐Syn pathology. During this process, extracellular α‐Syn can activate microglia and neuroinflammation, which plays an important role in PD. However, the effect of extracellular α‐Syn on microglia autophagy is poorly understood. In the present study, we reported that extracellular α‐Syn inhibited the autophagy initiation, as indicated by LC3‐II reduction and p62 protein elevation in BV2 and cultured primary microglia. The in vitro findings were verified in microglia‐enriched population isolated from α‐Syn‐overexpressing mice induced by adeno‐associated virus (AAV2/9)‐encoded wildtype human α‐Syn injection into the substantia nigra (SN). Mechanistically, α‐Syn led to microglial autophagic impairment through activating toll‐like receptor 4 (Tlr4) and its downstream p38 and Akt‐mTOR signaling because Tlr4 knockout and inhibition of p38, Akt as well as mTOR prevented α‐Syn‐induced autophagy inhibition. Moreover, inhibition of Akt reversed the mTOR activation but failed to affect p38 phosphorylation triggered by α‐Syn. Functionally, the in vivo evidence showed that lysozyme 2 Cre (Lyz2 ^cre)‐mediated depletion of autophagy‐related gene 5 (Atg5) in microglia aggravated the neuroinflammation and dopaminergic neuron losses in the SN and exacerbated the locomotor deficit in α‐Syn‐overexpressing mice. Taken together, the results suggest that extracellular α‐Syn, via Tlr4‐dependent p38 and Akt‐mTOR signaling cascades, disrupts microglial autophagy activity which synergistically contributes to neuroinflammation and PD development.     

Neurotherapeutic effects of novel HO‐1 inhibitors in vitro and in a transgenic mouse model of Alzheimer's disease

Heme oxygenase‐1 (HO‐1) encoded by the HMOX1 gene is a 32‐kDa stress protein that catabolizes heme to biliverdin, free iron, and carbon monoxide (CO). Glial HO‐1 is over‐expressed in the CNS of subjects with Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). The HMOX1 gene is exquisitely sensitive to oxidative stress and is induced in brain and other tissues in various models of disease and trauma. Induction of the glial HMOX1 gene may lead to pathological brain iron deposition, intracellular oxidative damage, and bioenergetic failure in AD and other human CNS disorders such as PD and MS. Therefore, targeted suppression of glial HO‐1 hyperactivity may prove to be a rational and effective therapeutic intervention in AD and related neurodegenerative disorders. In this study, we report the effects of QC‐47, QC‐56, and OB‐28, novel azole‐based competitive and reversible inhibitors of HO‐1, on oxidative damage to whole‐cell and mitochondrial compartments in rat astrocytes transfected with the HMOX1 gene. We also report the effect of OB‐28 on the behavior and neuropathology of APP_swe/PS1_?E9 mice. OB‐28 was found to reduce oxidative damage to whole‐cell and mitochondrial compartments in rat astrocytes transfected with the HMOX1 gene. Moreover, OB‐28 was found to significantly counter behavioral deficits and neuropathological alterations in APP_swe/PS1_?E9 mice. Attenuation of AD‐associated behavioral deficits and neuropathological changes suggests that HO‐1 may be a promising target for neuroprotective intervention in AD and other neurodegenerative diseases.

     

Acetylation as a major determinant to microtubule-dependent autophagy: Relevance to Alzheimer's and Parkinson disease pathology

Protein post-translational modifications (PTMs) that potentiate protein aggregation have been implicated in several neurological disorders, including Alzheimer's (AD) and Parkinson's disease (PD). In fact, Tau and alpha-synuclein (ASYN) undergo several PTMs potentiating their aggregation and neurotoxicity.Recent data posits a role for acetylation in Tau and ASYN aggregation. Herein we aimed to clarify the role of Sirtuin-2 (SIRT2) and HDAC6 tubulin deacetylases as well as p300 acetyltransferase in AD and PD neurodegeneration. We used transmitochondrial cybrids that recapitulate pathogenic alterations observed in sporadic PD and AD patient brains and ASYN and Tau cellular models.We confirmed that Tau protein and ASYN are microtubules (MTs)-associated proteins (MAPs). Moreover, our results suggest that α-tubulin acetylation induced by SIRT2 inhibition is functionally associated with the improvement of MT dynamic determined by decreased Tau phosphorylation and by increased Tau/tubulin and ASYN/tubulin binding. Our data provide a strong evidence for a functional role of tubulin and MAPs acetylation on autophagic vesicular traffic and cargo clearance. Additionally, we showed that an accumulation of ASYN oligomers imbalance mitochondrial dynamics, which further compromise autophagy. We also demonstrated that an increase in Tau acetylation is associated with Tau phosphorylation. We found that p300, HDAC6 and SIRT2 influences Tau phosphorylation and autophagic flux in AD. In addition, we demonstrated that p300 and HDAC6 modulate Tau and Tubulin acetylation.Overall, our data disclose the role of Tau and ASYN modifications through acetylation in AD and PD pathology, respectively. Moreover, this study indicates that MTs can be a promising therapeutic target in the field of neurodegenerative disorders in which intracellular transport is altered.     

Short-term exposure to dim light at night disrupts rhythmic behaviors and causes neurodegeneration in fly models of tauopathy and Alzheimer's disease

The accumulation and aggregation of phosphorylated tau proteins in the brain are the hallmarks for the onset of Alzheimer's disease (AD). In addition, disruptions in circadian rhythms (CRs) with altered sleep-wake cycles, dysregulation of locomotion, and increased memory defects have been reported in patients with AD. Drosophila flies that have an overexpression of human tau protein in neurons exhibit most of the symptoms of human patients with AD, including locomotion defects and neurodegeneration. Using the fly model for tauopathy/AD, we investigated the effects of an exposure to dim light at night on AD symptoms. We used a light intensity of 10 lux, which is considered the lower limit of light pollution in many countries. After the tauopathy flies were exposed to the dim light at night for 3 days, the flies showed disrupted CRs, altered sleep-wake cycles due to increased pTau proteins and neurodegeneration, in the brains of the AD flies. The results indicate that the nighttime exposure of tauopathy/AD model Drosophila flies to dim light disrupted CR and sleep-wake behavior and promoted neurodegeneration.     

Membrane-lipid homeostasis in a prodromal rat model of Alzheimer's disease: Characteristic profiles in ganglioside distributions during aging detected using MALDI imaging mass spectrometry

Background

Accumulation of simple gangliosides GM2 and GM3, and gangliosides with longer long-chain bases (d20:1) have been linked to toxicity and the pathogenesis of Alzheimer's disease (AD). Conversely, complex gangliosides, such as GM1, have been shown to be neuroprotective. Recent evidence using matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) has demonstrated that a-series gangliosides are differentially altered during normal aging, yet it remains unclear how simple species are shifting relative to complex gangliosides in the prodromal stages of AD.

From structure to clinic: Design of a muscarinic M1 receptor agonist with the potential to treat Alzheimer’s disease

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Proteome characterization of splenocytes from an Aβpp/ps‐1 Alzheimer's disease model

Alzheimer's disease (AD) is the sixth leading cause of US deaths. In addition to neurodegenerative deficits in AD, changes in the immune system have also been observed. Proteomic analysis of specific immune cell populations may help gain insights into mechanisms of peripheral immunity in AD. Herein, we report proteome characterization for two subsets of splenocytes (i.e. CD90+ cells and a heterogeneous pool of CD90? cells) from a double transgenic mutant amyloid precursor protein/presenilin‐1 (Aβpp/ps‐ 1) AD mouse model. Overall, 906 proteins were identified from both cell types with 275 and 334 proteins uniquely identified as CD90+ and CD90? cells, respectively. Proteins identified in CD90+ and CD90? cells were significantly involved in 18 and 19 KEGG pathways, respectively. Amongst these, pathways associated with AD and antigen processing and presentation were identified in CD90+ and CD90? subsets, respectively. This is the first study to provide a reference proteome map for splenocyte populations in A βpp/ps‐ 1 double transgenic mice which will be helpful for future studies focused on understanding peripheral changes in this model. All MS data have been deposited in the ProteomeXchange with identifier PXD000203 ( http://proteomecentral.proteomexchange.org/dataset/PXD000203 ).     

DNA polymerase β decrement triggers death of olfactory bulb cells and impairs olfaction in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) involves the progressive degeneration of neurons critical for learning and memory. In addition, patients with AD typically exhibit impaired olfaction associated with neuronal degeneration in the olfactory bulb (OB). Because DNA base excision repair (BER) is reduced in brain cells during normal aging and AD, we determined whether inefficient BER due to reduced DNA polymerase‐β (Polβ) levels renders OB neurons vulnerable to degeneration in the 3xTgAD mouse model of AD. We interrogated OB histopathology and olfactory function in wild‐type and 3xTgAD mice with normal or reduced Polβ levels. Compared to wild‐type control mice, Polβ heterozygous (Polβ^+/?), and 3xTgAD mice, 3xTgAD/Polβ^+/? mice exhibited impaired performance in a buried food test of olfaction. Polβ deficiency did not affect the proliferation of OB neural progenitor cells in the subventricular zone. However, numbers of newly generated neurons were reduced by approximately 25% in Polβ^+/? and 3xTgAD mice, and by over 60% in the 3xTgAD/Polβ^+/? mice compared to wild‐type control mice. Analyses of DNA damage and apoptosis revealed significantly greater degeneration of OB neurons in 3xTgAD/Polβ^+/? mice compared to 3xTgAD mice. Levels of amyloid β‐peptide (Aβ) accumulation in the OB were similar in 3xTgAD and 3xTgAD/Polβ^+/? mice, and cultured Polβ‐deficient neurons exhibited increased vulnerability to Aβ‐induced death. Olfactory deficit is an early sign in human AD, but the mechanism is not yet understood. Our findings in a new AD mouse model demonstrate that diminution of BER can endanger OB neurons, and suggest a mechanism underlying early olfactory impairment in AD.     

“Amyloid‐beta accumulation cycle” as a prevention and/or therapy target for Alzheimer's disease

The cell cycle and its regulators are validated targets for cancer drugs. Reagents that target cells in a specific cell cycle phase (e.g., antimitotics or DNA synthesis inhibitors/replication stress inducers) have demonstrated success as broad‐spectrum anticancer drugs. Cyclin‐dependent kinases (CDKs) are drivers of cell cycle transitions. A CDK inhibitor, flavopiridol/alvocidib, is an FDA‐approved drug for acute myeloid leukemia. Alzheimer's disease (AD) is another serious issue in contemporary medicine. The cause of AD remains elusive, although a critical role of latent amyloid‐beta accumulation has emerged. Existing AD drug research and development targets include amyloid, amyloid metabolism/catabolism, tau, inflammation, cholesterol, the cholinergic system, and other neurotransmitters. However, none have been validated as therapeutically effective targets. Recent reports from AD‐omics and preclinical animal models provided data supporting the long‐standing notion that cell cycle progression and/or mitosis may be a valid target for AD prevention and/or therapy. This review will summarize the recent developments in AD research: (a) Mitotic re‐entry, leading to the “amyloid‐beta accumulation cycle,” may be a prerequisite for amyloid‐beta accumulation and AD pathology development; (b) AD‐associated pathogens can cause cell cycle errors; (c) thirteen among 37 human AD genetic risk genes may be functionally involved in the cell cycle and/or mitosis; and (d) preclinical AD mouse models treated with CDK inhibitor showed improvements in cognitive/behavioral symptoms. If the “amyloid‐beta accumulation cycle is an AD drug target” concept is proven, repurposing of cancer drugs may emerge as a new, fast‐track approach for AD management in the clinic setting.     

The tumor-associated antigen 90K/Mac-2-binding protein secreted by human colon carcinoma cells enhances extracellular levels of promatrilysin and is a novel substrate of matrix metalloproteinases-2, -7 (matrilysin) and -9: Implications of proteolytic cleavage

Background

The tumor-associated antigen 90K (TAA90K)/Mac-2-binding protein is expressed at elevated level in cancerous tissues and associated with poor prognosis. Since TAA90K has been implicated in the restructuring of the extracellular matrix, we examined the functional relationship between colon cancer cell-derived TAA90K and the matrix metalloproteinase (MMP) promatrilysin (proMMP-7), and also tested whether TAA90K is a novel substrate for MMPs-2, -7 and -9.

Methods

The effect of TAA90K on proMMP-7 levels in HT-29 conditioned media was quantified by enzyme-linked immunosorbent assays. Binding of TAA90K to MMPs, extracellular matrix proteins and galectin-3 was measured by solid-phase binding assays. Proteolytic cleavage of TAA90K by MMPs was documented by SDS-PAGE and protein sequencing analysis.

Results

TAA90K enhanced extracellular levels of proMMP-7 in HT-29 cells. In addition, TAA90K was cleaved by MMPs-2, -7 and -9. MMP-7-mediated cleavage of TAA90K did not affect its binding to MMP-7, laminin-1, collagen IV and galectin-3 but reduced its interaction with fibronectin and laminin-10, and lowered the levels of proMMP-7 in the HT-29 medium.

Conclusion

TAA90K is a novel substrate for MMPs-2, -7 and -9 and modulates proMMP-7 levels in colon cancer cells.

General significance

Proteolytic cleavage of TAA90K may have functional implications in colon cancer.