Mechanisms Of Alzheimer's Disease Research Articles

Longitudinal changes in the control mechanisms for blood pressure and cerebral blood flow in Alzheimer's disease: Secondary results of a randomized controlled trial.

Dynamic cerebral autoregulation (dCA) and baroreflex sensitivity (BRS) are key mechanisms involved in the homeostasis of blood pressure (BP) and cerebral blood flow. We assessed changes in these mechanisms in Alzheimer's disease (AD) during a 1.5 year follow-up. In this secondary analysis of a randomized controlled trial we measured beat-to-beat BP, heart rate, and cerebral blood flow velocity at baseline, 0.5 and 1.5 years, during: rest (spontaneous oscillations), repeated sit-stand maneuvers (induced oscillations), an orthostatic challenge, and hypo- and hypercapnia. dCA was estimated using transfer function analysis and the autoregulatory index on spontaneous and induced oscillations. BRS was estimated by calculating the heart rate response to BP changes during induced oscillations. Linear mixed models were used to assess changes over time. 56 patients were included (mean age:73±6 years, 57% female). BRS did not change over time. dCA parameters showed small changes after 0.5 years, suggestive of a reduction in efficiency (e.g. higher gain [linear mixed effect model: B=0.09, SE=0.03, P= 0.008] and lower phase [B=-9.7, SE= 3.2, P= 0.004] in the very low frequency domain, and lower autoregulatory index during induced oscillations [B=-0.69, SE=0.26, P= 0.010]). These changes did not show further progression after 1.5 years of follow-up. In this sample of patients with dementia due to AD we found no evidence that dCA or BRS become impaired during AD progression. This paves the way for further studies that investigate the safety and benefits of antihypertensive treatment in patients with AD.

An Insight in Pathophysiological Mechanism of Alzheimer's Disease and its Management Using Plant Natural Products

An Insight in Pathophysiological Mechanism of Alzheimer's Disease and its Management Using Plant Natural Products

Effect of Combined Electroacupuncture and Selegiline Treatment in Alzheimer's Disease: An Animal Model.

The complexity of pathological mechanisms in Alzheimer’s disease (AD) poses significant challenges to the development of corresponding drugs. Symptom-specific pharmacological interventions and alternative treatments provide promising treatment possibilities. Therefore, we considered a combination of selegiline (SEL) and electroacupuncture (EA). We used an animal model with AD to investigate the effect of a combination of these treatments on cognitive function. 5XFAD mice received a week of SEL treatment and 2 weeks of EA. Novel object recognition and Y-maze tests were subsequently performed to assess their cognitive functions. To determine the molecular action of the combination treatment, Western blots, Aβ1-42 enzyme-linked immunosorbent assays (ELISA), and micro-positron-emission tomography were also performed to assess pathological markers and processes. The results were assessed based on the difference between untreated transgenic, SEL-treated, and SEL- and EA-treated groups of mice. Mice in the combined treatment group demonstrated significantly better cognitive functions, and lesser neuroinflammation than the comparative groups. In addition, mice treated with a combination of SEL and EA did not demonstrate a direct modulation of insoluble Aβ but demonstrated greater glucose metabolism. Our findings demonstrated that SEL combined with EA treatment was associated with better cognitive functioning due to inhibition of neuroinflammation and increased glucose metabolism relative to the comparative groups in a mouse model with AD.

Gene‐neuroimaging brain model decodes neuropathological mechanisms in Alzheimer’s disease

AbstractBackgroundAlzheimer’s disease (AD) is characterized by aberrations of several biological processes/factors (e.g., genes, misfolded proteins, atrophy). Investigating the interplay between these factors at multiple scales can advance our understanding of AD and facilitate the development of cost‐effective treatments while unifying biomarkers for early AD diagnosis and prevention. We propose a mathematical framework that models how gene expression (GE) modulates the interaction between six macroscopic imaging modalities in AD progression. The identified genes and pathways provide novel insight into AD pathology.Method1) We pre‐processed 6 longitudinal neuroimaging data (beta‐amyloid and tau proteins, cerebral blood flow, glucose metabolism, R‐fMRI, and grey matter volume) of 157 healthy and 317 diseased subjects from ADNI. 2) Using GE data of 6 neurotypical brains from Allen Human Brain Atlas, we derived brain‐wide GE of 990 genes with leading roles in central biological functions. 3) We built a mathematical model that incorporates: (i) disease‐related longitudinal changes in neuroimaging data, (ii) GE‐modulated interactions between the different neuroimaging modalities, (iii) propagation of alterations resulting from (ii) across brain networks. 4) By evaluating the latent relationship between GE modulating effects and cognitive measures (MMSE, ADAS, executive function, memory score) of 127 subjects (converters) who advanced to subsequent stages in the AD continuum, causal genes and altered pathways in AD progression were identified.ResultThe model explains 64% of the common variance between GE‐dependent brain alterations and cognitive scores of the converters. We identified 89 disease‐driving genes, including some notable previously identified AD genetic determinants: APPB2, TOP2A, CLU, BACE1 and CD44. The biological factors causally modulated by each gene, and factor alterations resulting from the modulation were also reported; e.g., our model reveals that APPB2 gene modulates beta‐amyloid to cause longitudinal alteration of beta‐amyloid, while CLU could interact with vascular flow to alter tau protein (Fig. 1). We also identified 54 likely altered pathways in AD evolution.ConclusionWe developed a mathematical model to investigate the influence of gene expression on multifactorial alterations of biological processes in AD progression. Our results are strongly consistent with previously reported studies and provided further insight into the molecular mechanism underlying AD progression.

Genome‐wide profiling of the noncoding regulatory mechanisms in Alzheimer’s disease

AbstractBackgroundGenome‐wide association studies (GWAS) have identified genetic variants associated with Alzheimer’s Disease (AD), but the majority are noncoding and may affect transcriptional regulatory elements such as enhancers. While prior post‐GWAS analyses focused on analyzing only top GWAS signals, this study focuses on a systematic genome‐wide analysis of all significant GWAS signals aimed at identifying a more complete set of causal variants given a complex linkage disequilibrium (LD) genome structures and the regulatory mechanisms, and tissues/cell types.MethodTo perform genome‐wide analysis of GWAS summary statistics (NIAGADS NG00036) from the IGAP study [Lambert et al., 2013], we adopted INFERNO (http://inferno.lisanwanglab.org), a recent method for post‐GWAS analysis of non‐coding variants. INFERNO integrates GWAS data with hundreds of publicly available functional genomics datasets (e.g., ENCODE, FANTOM5, GTEx, HOMER) across 485 tissues and cell types to facilitate identification of the regulatory mechanisms and tissue/cell types affected by noncoding genetic variants.ResultsGenome‐wide INFERNO analysis identified 168 distinct loci by pruning all genome‐wide significant (p‐value < 5e‐8) GWAS variants using LD structure, a significant increase compared to original top‐SNP analysis (19 loci). Across these 168 distinct loci, INFERNO identified 1,358 candidate potentially causal variants in LD. Around 6% of these variants were localized in coding exons, 67% overlapped enhancers in at least one tissue and 57% overlapped transcription factor binding sites. Co‐localization analysis of GWAS and eQTL data (GTEx_v6p) identified tissue‐specific effects of 53 variants on 43 genes across 16 INFERNO tissue categories, with 12 variants affecting expression of 16 genes in the blood (RP11‐1036E20.9, ZNF223, ZNF285B, RP11‐286H15.1, FAM115D, EPHA1‐AS1, TAS2R60, TAS2R62P, PTK2B) and brain (CR1, ABCA7, POLR2E, EML2, PPM1N, RP11‐385F7.1, FAM115C). These INFERNO‐identified genes include both novel and genes previously implicated in AD. E.g. EPHA1‐AS1 activity was confirmed by luciferase reporter assay [Amlie‐Wolf et al., 2019]. Additionally, our analysis found that PTK2B gene, an early marker of Tau pathology [Dourlen et al., 2016], is regulated by rs28834970 that also disrupts binding motif of HLF(bZIP) in blood.ConclusionGenome‐wide INFERNO analysis confirmed experimentally validated and discovered additional plausible biological mechanisms related to AD. These can help to inform the development of better AD therapeutic targets.

Multivariate genome wide association and network analysis of subcortical imaging phenotypes in Alzheimer\u2019s disease

BackgroundGenome-wide association studies (GWAS) have identified many individual genes associated with brain imaging quantitative traits (QTs) in Alzheimer’s disease (AD). However single marker level association discovery may not be able to address the underlying biological interactions with disease mechanism.ResultsIn this paper, we used the MGAS (Multivariate Gene-based Association test by extended Simes procedure) tool to perform multivariate GWAS on eight AD-relevant subcortical imaging measures. We conducted multiple iPINBPA (integrative Protein-Interaction-Network-Based Pathway Analysis) network analyses on MGAS findings using protein-protein interaction (PPI) data, and identified five Consensus Modules (CMs) from the PPI network. Functional annotation and network analysis were performed on the identified CMs. The MGAS yielded significant hits within APOE, TOMM40 and APOC1 genes, which were known AD risk factors, as well as a few new genes such as LAMA1, XYLB, HSD17B7P2, and NPEPL1. The identified five CMs were enriched by biological processes related to disorders such as Alzheimer’s disease, Legionellosis, Pertussis, and Serotonergic synapse.ConclusionsThe statistical power of coupling MGAS with iPINBPA was higher than traditional GWAS method, and yielded new findings that were missed by GWAS. This study provides novel insights into the molecular mechanism of Alzheimer’s Disease and will be of value to novel gene discovery and functional genomic studies.

Module Analysis Using Single-Patient Differential Expression Signatures Improves the Power of Association Studies for Alzheimer's Disease.

The causal mechanism of Alzheimer's disease is extremely complex. Achieving great statistical power in association studies usually requires a large number of samples. In this work, we illustrated a different strategy to identify AD risk genes by clustering AD patients into modules based on their single-patient differential expression signatures. The evaluation suggested that our method could enrich AD patients with similar clinical manifestations. Applying this to a cohort of only 310 AD patients, we identified 174 AD risk loci at a strict threshold of empirical p < 0.05, while only two loci were identified using all the AD patients. As an evaluation, we collected 23 AD risk genes reported in a recent large-scale meta-analysis and found that 18 of them were rediscovered by association studies using clustered AD patients, while only three of them were rediscovered using all AD patients. Functional annotation suggested that AD-associated genetic variants mainly disturbed neuronal/synaptic function. Our results suggested module analysis helped to enrich AD patients affected by the common risk variants.

Emergence of Barrel Motif in Amyloid-β Trimer: A Computational Study.

Amyloid-β (Aβ) peptides form assemblies that are pathological hallmarks of Alzheimer’s disease. Aβ oligomers are soluble, mobile, and toxic forms of the peptide that act in the extracellular space before assembling into protofibrils and fibrils. Therefore, oligomers play an important role in the mechanism of Alzheimer’s disease. Since it is difficult to determine by experiment the atomic structures of oligomers, which accumulate fast and are polymorphic, computer simulation is a useful tool to investigate elusive oligomers’ structures. In this work, we report extended all-atom molecular dynamics simulations, both canonical and replica exchange, of Aβ(1–42) trimer starting from two different initial conformations: (i) the pose produced by the best docking of a monomer aside of a dimer (simulation 1), representing oligomers freshly formed by assembling monomers, and (ii) a configuration extracted from an experimental mature fibril structure (simulation 2), representing settled oligomers in equilibrium with extended fibrils. We showed that in simulation 1, regions with small β-barrels are populated, indicating the chance of spontaneous formation of domains resembling channel-like structures. These structural domains are alternative to those more representative of mature fibrils (simulation 2), the latter showing a stable bundle of C-termini that is not sampled in simulation 1. Moreover, trimer of Aβ(1–42) can form internal pores that are large enough to be accessed by water molecules and Ca2+ ions.

Novel Alzheimer Disease Risk Loci and Pathways in African American Individuals Using the African Genome Resources Panel

Compared with non-Hispanic White individuals, African American individuals from the same community are approximately twice as likely to develop Alzheimer disease. Despite this disparity, the largest Alzheimer disease genome-wide association studies to date have been conducted in non-Hispanic White individuals. In the largest association analyses of Alzheimer disease in African American individuals, ABCA7, TREM2, and an intergenic locus at 5q35 were previously implicated. To identify additional risk loci in African American individuals by increasing the sample size and using the African Genome Resource panel. This genome-wide association meta-analysis used case-control and family-based data sets from the Alzheimer Disease Genetics Consortium. There were multiple recruitment sites throughout the United States that included individuals with Alzheimer disease and controls of African American ancestry. Analysis began October 2018 and ended September 2019. Diagnosis of Alzheimer disease. A total of 2784 individuals with Alzheimer disease (1944 female [69.8%]) and 5222 controls (3743 female [71.7%]) were analyzed (mean [SD] age at last evaluation, 74.2 [13.6] years). Associations with 4 novel common loci centered near the intracellular glycoprotein trafficking gene EDEM1 (3p26; P = 8.9 × 10-7), near the immune response gene ALCAM (3q13; P = 9.3 × 10-7), within GPC6 (13q31; P = 4.1 × 10-7), a gene critical for recruitment of glutamatergic receptors to the neuronal membrane, and within VRK3 (19q13.33; P = 3.5 × 10-7), a gene involved in glutamate neurotoxicity, were identified. In addition, several loci associated with rare variants, including a genome-wide significant intergenic locus near IGF1R at 15q26 (P = 1.7 × 10-9) and 6 additional loci with suggestive significance (P ≤ 5 × 10-7) such as API5 at 11p12 (P = 8.8 × 10-8) and RBFOX1 at 16p13 (P = 5.4 × 10-7) were identified. Gene expression data from brain tissue demonstrate association of ALCAM, ARAP1, GPC6, and RBFOX1 with brain β-amyloid load. Of 25 known loci associated with Alzheimer disease in non-Hispanic White individuals, only APOE, ABCA7, TREM2, BIN1, CD2AP, FERMT2, and WWOX were implicated at a nominal significance level or stronger in African American individuals. Pathway analyses strongly support the notion that immunity, lipid processing, and intracellular trafficking pathways underlying Alzheimer disease in African American individuals overlap with those observed in non-Hispanic White individuals. A new pathway emerging from these analyses is the kidney system, suggesting a novel mechanism for Alzheimer disease that needs further exploration. While the major pathways involved in Alzheimer disease etiology in African American individuals are similar to those in non-Hispanic White individuals, the disease-associated loci within these pathways differ.

Inhibitor Kappa B Kinase β, Modulated by DJ-1/p-VHL, Reduces Phosphorylated Tau (p-Tau) Accumulation via Autophagy in Alzheimer’s Disease Model

It has been demonstrated Inhibitor Kappa B Kinase β (IKKβ) facilitates autophagy, which in turn mediates p-Tau protein clearance. However, the specific regulatory mechanism in Alzheimer’s disease (AD) remains unclear. Firstly, AD model was generated by the intracerebroventricular (ICV) injection of the Β-amyloid 1–42 (Aβ1–42) peptide. Subsequently, mice were injected with shRNA adenoviral transduction particles designed to target DJ-1 or Aβ1–42 or Aβ1–42 + shNC or Aβ1–42 + shRNA against DJ-1. shRNA against DJ-1 were injected into hippocampus of mice (8 × 104 viral particles for each mice) for seven consecutive days. Immunohistochemistry was performed to detect the accumulation of Aβ in the hippocampus of mice, and Hematoxylin-Eosin (HE) staining assay was carried to detect pathological changes in the hippocampus of mice. Further, sh-IKKβ, shDJ-1, pcDNA-IKKβ and pcDNA-DJ-1 plasmids were transfected into HT-22 cells, MTT assay, TUNEL staining and Hoechst staining were performed to detect cell viability and apoptosis, respectively. Western blotting was carried to measure the relative expression of proteins. Findings indicated that Aβ1–42 inhibited autophagy and up-regulated p-Tau protein expression; Overexpression of IKKβ and DJ-1 all rescued the autophagy inhibited by Aβ1–42 and down-regulated p-Tau protein expression induced by Aβ1–42; DJ-1 up-regulated IKKβ via p-VHL, further promoted autophagy and reduced the expression of p-Tau protein; DJ-1 knockdown inhibited autophagy and up-regulated p-Tau protein expression, resulting in delayed behavior in mice. In conclusion, IKKβ, modulated by DJ-1/p-VHL, reduces p-Tau accumulation via autophagy in AD’s disease model. This study may provide theoretical basis for the treatment of AD.

Comparison of the reaction of methylglyoxal (MGO) with murine and human amyloid beta (Aβ): Insights into a mechanism of Alzheimer’s disease (AD)

Reacted with methylglyoxal (MGO), murine Aβ(1-40) (mAβ) produced significantly less superoxide anion (O2•–) compared to human Aβ(1-40) (hAβ). The reactions of MGO with mAβ(R13H), hAβ(H13F), Nα-acetyl-l-lysine, and Nα-acetyl-l-arginine implied that the lack of His13 in mAβ prohibits its Lys16 residue from reacting to produce cross-linked reaction products and O2•–. Our results suggest that murine brains are under less oxidative stress than human brains, which may be one of the reasons why rodents do not develop AD-like symptoms, and which provides further insight into a chemical mechanism for the development of AD in humans.

Overexpression of miR-26a-5p Suppresses Tau Phosphorylation and Aβ Accumulation in the Alzheimer's Disease Mice by Targeting DYRK1A.

It is reported that miR-26a-5p could regulate neuronal development, but its underlying mechanisms in Alzheimer's disease (AD) progression is unclear. APP (swe)/PS1 (ΔE9) transgenic mice served as AD mice. Morris water maze test was used to measure the spatial learning and memory ability of mice. The expressions of miR-26a-5p, DYRK1A, phosphorylated-Tau, Aβ40, and Aβ42 were detected. The relationship between miR- 26a-5p and DYRK1A was explored using dual luciferase reporter assay. The effects of miR-26a- 5p on AD mice was determined. AD mice walked a lot of wrong ways to find the platform area and the latency time to reach the platform was longer. There was low expression of MiR-26a-5p in AD mice. Overexpression of miR-26a-5p inhibited Tau phosphorylation and Aβ accumulation. MiR-26a-5p negatively regulated DYRK1A via targeting its 3'UTR. In vivo, increased miR-26a-5p down-regulated Aβ40, Aβ42, p-APP and p-Tau levels in AD mice through decreasing DYRK1A. Meanwhile, the swimming path and the latency time, to reach the platform, was shorten after enhancing miR-26a-5p expression. Overexpression of miR-26a-5p could repress Tau phosphorylation and Aβ accumulation via down-regulating DYRK1A level in AD mice.

LTP-like plasticity is impaired in amyloid-positive amnestic MCI but independent of PET-amyloid burden

Transcranial magnetic stimulation (TMS) reveals decreased efficacy of long-term potentiation-like (LTP-like) neuroplastic mechanisms in Alzheimer's disease (AD). However, it is not yet known whether LTP-like plasticity is also impaired in prodromal AD, or how abnormal TMS measures are related to established AD biomarkers. Here, we investigated the LTP-like response to intermittent theta-burst stimulation in 17 amyloid-positive participants with amnestic mild cognitive impairment (MCI) and 10 cognitively unimpaired controls. Our results showed a lack of LTP-like neuromodulation in MCI compared with controls that was unrelated to quantitative amyloid-beta burden on positron emission tomography. Surprisingly, greater LTP-like response was related to worse memory function in the MCI group, highlighting the complex role of neuroplasticity in the prodromal stages of AD. Overall, our results demonstrate abnormal LTP-like plasticity using intermittent theta-burst stimulation assessment in amyloid-positive participants with MCI. These findings support the potential for development of TMS measures as prognostic markers or therapeutic targets in early-stage symptomatic AD.

Genomic mechanisms in Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disease and, owing to its increasing prevalence, represents one of the leading public health problems in aging populations. The molecular causes underlying the onset and progression of AD are manifold and hitherto still incompletely understood. Research over nearly four decades has clearly delineated genetics to play a crucial role in AD susceptibility, likely in concert with non-genetic factors. The field has gained considerable momentum and novel insights over the past 10years owing to the advent and application of high-throughput genomics technologies in datasets of increasing size. In this contribution to the Mini-Symposium on the Molecular Etiology of Alzheimer's Disease, we review the current status of genomics research in AD. To this end, we scrutinize and discuss the main findings from the two largest and most current genome-wide association studies (GWAS) in the field, that is, the papers published by Jansen et al (Nat Genet 51:404-413) and Kunkle et al (Nat Genet 51:414-430). Particular focus is laid on genomics findings overlapping across both studies and on the novel insights they provide in terms of improving our understanding of the "genomic mechanisms" underlying this devastating disease.

SAMP8 Mice as a Model of Age-Related Cognition Decline with Underlying Mechanisms in Alzheimer's Disease.

Alzheimer's disease (AD) is a highly age-related cognitive decline frequently attacking the elderly. Senescence-accelerated mouse-prone 8 (SAMP8) is an ideal model to study AD, displaying age-related learning and memory disorders. SAMP8 mice exhibit most features of pathogenesis of AD, including an abnormal expression of anti-aging factors, oxidative stress, inflammation, amyloid-β (Aβ) deposits, tau hyperphosphorylation, endoplasmic reticulum stress, abnormal autophagy activity, and disruption of intestinal flora. SAMP8 mice, therefore, have visualized the understanding of AD, and also provided effective ways to find new therapeutic targets. This review focused on the age-related pathogenesis in SAMP8 mice, to advance the understanding of age-related learning and memory decline and clarify the mechanisms. Furthermore, this review will provide extensive foundations for SAMP8 mice used in therapeutics for AD.

A Striking Bone Phenotype in the Familial Danish Dementia (FDD) Tg+ Mouse

Familial Danish Dementia (FDD) is an autosomal dominant neurodegenerative disease caused by a 10‐nucleotide insertion mutation in the BRI(2) gene (aka ITM2B) resulting in a frame‐shift. The resulting Danish amyloid precursor protein (ADanPP) is then cleaved an amyloidogenic peptide that deposits in the brain and cerebral vessels. FDD in patients results in a range of clinical defects, including cataracts, hearing defects, cerebellar ataxia, slurred speech, gait disturbances, psychosis, and dementia. With emerging evidence that human bone defects are associated with neurodegenerative disease, we phenotyped bone in 12‐month FDD Tg+ mice. FDD Tg+ mice exhibit abnormal grooming by 9 months and have Ab plaques and behavior deficits by 12 months, paralleling mechanisms in Alzheimer disease. At 12 months of age, femurs from FDD Tg+ mice were assessed by mCT (SkyScan 1172, 9 mm resolution) in the distal metaphysis (1 mm) and mid‐diaphysis regions for trabecular and cortical areas, respectively. Both male and female femurs exhibited significantly reduced bone volumes (44%) vs. age‐, strain‐matched wildtype mice; male FDD Tg+ femurs showed a 24% reduction in bone mineral density.Trabecular boneFemales FDD Tg+ femurs had a 24% reduction in the trabecular thickness (vs. controls), whereas male FDD Tg+ femurs exhibited a 24% increase in the trabecular separation and 40% reduction in the trabecular number (vs. controls).Cortical boneFemale FDD Tg+ femurs had a 15% reduction in bone marrow area and 8.6% endocortical thickness compared to controls. Male FDD Tg+ femurs had reduced total cross‐sectional area and endocortical thickness by about 8%, a 15% reduction in the marrow area, along with a reduced periosteal thickness and increased cortical thickness vs. controls. These results indicate that FDD Tg+ mice have significant bone phenotypes in parallel with previously observed brain defects, suggesting therapeutic interventions may want to consider how neurodegeneration might impact other critical organs in the body such as bone.Support or Funding InformationLilly Foundation/Indiana Center for Musculoskeletal Health/ IU School of Medicine, Physician Scientist Initiative, Scientific Research Initiative

Reader response: INTREPAD: A randomized trial of naproxen to slow progress of presymptomatic Alzheimer disease.

I read with interest the Null Hypothesis article by Meyer et al.1 In 2001, Weggen et al.2 suggested that flurbiprofen and ibuprofen had an effect on gamma secretase not shared by other cyclooxygenase inhibitors. This finding, along with several other failed studies of anti-inflammatory mechanisms in Alzheimer disease (AD), suggests that the widely replicated epidemiologic findings of nonsteroidal anti-inflammatory drug (NSAID) benefit for decreasing AD risk could be related to the effect on gamma-secretase, not inflammation. A flurbiprofen study failed to show a benefit for patients with AD,3 but a considerable number of studies suggest that the NSAID-related benefit requires years of treatment before dementia develops, which the study by Meyer et al.1 was appropriately targeting. However, the question remains as to whether ibuprofen is the drug to test, not naproxen.

MiR-16-5p and miR-19b-3p prevent amyloid β-induced injury by targeting BACE1 in SH-SY5Y cells.

Alzheimer's disease is the most common neurodegenerative disease, characterized by accumulation of amyloid β peptides. MicroRNAs have been identified as significant regulators and therapeutic targets of Alzheimer's disease. However, the roles of miR-16-5p and miR-19b-3p and their mechanisms in Alzheimer's disease progression remain largely unknown. Amyloid β-treated SH-SY5Y cells were used to study Alzheimer's disease progression in vitro. Transfection was conducted into SH-SY5Y cells using Lipofectamine 2000. The expression levels of miR-16-5p, miR-19b-3p and beta-site amyloid precursor protein cleaving enzyme 1 (BACE1) were measured by quantitative real-time PCR or western blot, respectively. Cell viability and apoptosis were detected in amyloid β-treated SH-SY5Y cells by MTT or flow cytometry, respectively. The interaction between BACE1 and miR-16-5p or miR-19b-3p was explored by luciferase reporter and RNA immunoprecipitation analyses. The expression levels of miR-16-5p and miR-19b-3p were reduced but BACE1 protein expression was enhanced in SH-SY5Y cells after treatment of amyloid β. Overexpression of miR-16-5p or miR-19b-3p attenuated amyloid β-induced viability inhibition and apoptosis promotion in SH-SY5Y cells, while their knockdown exacerbated amyloid β-induced injury. BACE1 was confirmed as a target of miR-16-5p and miR-19b-3p and its overexpression aggravated amyloid β-induced loss of viability and production of apoptosis, while its depletion caused an opposite effect. Moreover, upregulation of BACE1 alleviated the regulatory effects of miR-16-5p and miR-19b-3p on amyloid β-induced injury. MiR-16-5p and miR-19b-3p relieved amyloid β-induced injury by targeting BACE1 in SH-SY5Y cells, indicating miR-16-5p and miR-19b-3p as protective agents for treatment of Alzheimer's disease.

Computational modeling of convergent mechanisms in Alzheimer’s and Parkinson’s disease with insulin signaling using biochemical systems theory

Abstract Computational modeling has significantly impacted clinical assessment and treatment of diseases by improving diagnosis, prognosis, discovery of novel biomarkers and developing new drugs that assures treatment for incurable diseases. In this study, a biochemical systems theory model was developed to explore crucial pathways involved in shared mechanisms between Alzheimer’s and Parkinson’s diseases and insulin signaling involved in Parkinson’s disease (PD). Mass kinetic concentration values and rate constants were retrieved from experiments cited in literature and simulations were developed using systems of ordinary differential equations. Calcium changes were reconstructed accounting reduced levels in diseased conditions. Simulations suggest that AD and PD share some of the important cellular pathways such as α-synuclein, tau phosphorylation, calcium homeostasis, ROS and TNF-α in spite of the differences in mechanisms and symptoms. Here, modeling relates the critical role insulin signaling may have in maintaining dopamine levels in PD patients.

Pharmacological inhibition of G9a/GLP restores cognition and reduces oxidative stress, neuroinflammation and β-Amyloid plaques in an early-onset Alzheimer's disease mouse model.

The implication of epigenetic mechanisms in Alzheimer’s disease (AD) has been demonstrated in several studies. UNC0642, a specific and potent inhibitor of methyltransferase activity G9a/GLP (G9a-like) complex, was evaluated in the 5XFAD mouse model. UNC0642 treatment rescued 5XFAD cognition impairment, reduced DNA-methylation (5-mC), increased hydroxymethylation (5-hmC), and decreased the di-methylation of lysine 9 of histone H3 (H3K9me2) levels in the hippocampus. Increases in the Nuclear Factor erythroid-2-Related Factor 2 (NRF2), Heme oxygenase decycling 1 (Hmox1) gene expression, and diminution in Reactive Oxygen Species (ROS) were also reported. Moreover, neuroinflammatory markers, such as Interleukin 6 (Il-6), Tumor necrosis factor-alpha (Tnf-α) gene expression, and Glial fibrillary acidic protein (GFAP) immunofluorescence were reduced by UNC0642 treatment. An increase in Nerve growth factor (Ngf), Nerve growth factor inducible (Vgf) gene expression, Brain-derived neurotrophic factor (BDNF), and Synaptophysin (SYN) were found after UNC0642 treatment. Importantly, a reduction in β-amyloid plaques was also observed. In conclusion, our work demonstrates that the inhibition of the G9a/GLP complex by UNC0642 delivered significant neuroprotective effects in 5XFAD mice, point out G9a/GLP as a new target for AD.