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.

Design, synthesis, and characterization of novel system x transport inhibitors: inhibition of microglial glutamate release and neurotoxicity.

Neuroinflammation appears to involve some degree of excitotoxicity promulgated by microglia, which release glutamate via the system x (Sx) cystine-glutamate antiporter. With the aim of mitigating this source of neuronal stress and toxicity, we have developed a panel of inhibitors of the Sx antiporter. The compounds were based on L-tyrosine, as elements of its structure align with those of glutamate, a primary physiological substrate of the Sx antiporter.

Thiadiazolidinone (TDZD) Analogs Inhibit Aggregation-Mediated Pathology in Diverse Neurodegeneration Models, and Extend Life- and Healthspan.

Chronic, low-grade inflammation has been implicated in aging and age-dependent conditions, including Alzheimer's disease, cardiomyopathy, and cancer. One of the age-associated processes underlying chronic inflammation is protein aggregation, which is implicated in neuroinflammation and a broad spectrum of neurodegenerative diseases such as Alzheimer's, Huntington's, and Parkinson's diseases. We screened a panel of bioactive thiadiazolidinones (TDZDs) from our in-house library for rescue of protein aggregation in human-cell and models of neurodegeneration.

Central repeat fragment of reelin leads to active reelin intracellular signaling and rescues cognitive deficits in a mouse model of reelin deficiency.

Reelin and its receptor, ApoER2, play important roles in prenatal brain development and postnatally in synaptic plasticity, learning, and memory. Previous reports suggest that reelin's central fragment binds to ApoER2 and receptor clustering is involved in subsequent intracellular signaling. However, limitations of currently available assays have not established cellular evidence of ApoER2 clustering upon binding of the central reelin fragment.

Amyloid β-Peptide Effects on Glucose Regulation Are Dependent on Apolipoprotein E Genotype.

The apolipoprotein E gene () confers the greatest genetic risk factor for Alzheimer's disease (AD), wherein the ε4 allele confers an elevated risk compared with the ε3 allele. Biological mechanisms that differ across these alleles have been explored in mouse models wherein the murine gene has undergone targeted replacement with sequences encoding human ApoE3 or ApoE4 (ApoE-TR mice). Such models have indicated that the two variants of ApoE produce differential effects on energy metabolism, including metabolic syndrome.

Liraglutide Counteracts Endoplasmic Reticulum Stress in Palmitate-Treated Hypothalamic Neurons without Restoring Mitochondrial Homeostasis.

One feature of high-fat diet-induced neurodegeneration in the hypothalamus is an increased level of palmitate, which is associated with endoplasmic reticulum (ER) stress, loss of CoxIV, mitochondrial fragmentation, and decreased abundance of MC4R. To determine whether antidiabetic drugs protect against ER and/or mitochondrial dysfunction by lipid stress, hypothalamic neurons derived from pre-adult mice and neuronal Neuro2A cells were exposed to elevated palmitate. In the hypothalamic neurons, palmitate exposure increased expression of ER resident proteins, including that of SERCA2, indicating ER stress.

Glucose transport in the regulation of T-cell activation: the journey may be as important as the destination.

A shift in the energy-metabolism balance from oxidative phosphorylation to glycolysis is observed in several phenomena, from oncogenesis to differentiation. And this shift is not merely an indicator of the phenotypic change-an increase in glucose delivery often drives the adaption. At first blush, it seems that any route of entry should be equivalent, as long as sufficient quantities are supplied.

Serine Racemase Expression Differentiates Aging from Alzheimer's Brain.

Aging is an inevitable process characterized by progressive loss of physiological integrity and increased susceptibility to cancer, diabetes, cardiovascular, and neurodegenerative diseases; aging is the primary risk factor for Alzheimer's disease (AD), the most common cause of dementia. AD is characterized by brain pathology, including extracellular deposition of amyloid aggregation and intracellular accumulation of neurofibrillary tangles composed of hyperphosphorylated tau protein. In addition, losses of synapses and a wide range of neurons are pivotal pathologies in the AD brain.

Alzheimer amyloid-β- peptide disrupts membrane localization of glucose transporter 1 in astrocytes: implications for glucose levels in brain and blood.

Alzheimer's disease (AD) is associated with disturbances in blood glucose regulation, and type-2 diabetes elevates the risk for dementia. A role for amyloid-β peptide (Aβ) in linking these age-related conditions has been proposed, tested primarily in transgenic mouse lines that overexpress mutated amyloid precursor protein (APP). Because APP has its own impacts on glucose regulation, we examined the BRI-Aβ42 line ("Aβ-tg"), which produces extracellular Aβ in the CNS without elevation of APP.

A Novel Microtubule-Binding Drug Attenuates and Reverses Protein Aggregation in Animal Models of Alzheimer's Disease.

Age-progressive neurodegenerative pathologies, including Alzheimer's disease (AD), are distinguished and diagnosed by disease-specific components of intra- or extra-cellular aggregates. Increasing evidence suggests that neuroinflammation promotes protein aggregation, and is involved in the etiology of neurological diseases. We synthesized and tested analogs of the naturally occurring tubulin-binding compound, combretastatin A-4.

Interleukin-1β drives NEDD8 nuclear-to-cytoplasmic translocation, fostering parkin activation via NEDD8 binding to the P-ubiquitin activating site.

Background: Neuroinflammation, typified by elevated levels of interleukin-1 (IL-1) α and β, and deficits in proteostasis, characterized by accumulation of polyubiquitinated proteins and other aggregates, are associated with neurodegenerative disease independently and through interactions of the two phenomena. We investigated the influence of IL-1β on ubiquitination via its impact on activation of the E3 ligase parkin by either phosphorylated ubiquitin (P-Ub) or NEDD8.

Methods: Immunohistochemistry and Proximity Ligation Assay were used to assess colocalization of parkin with P-tau or NEDD8 in hippocampus from Alzheimer patients (AD) and controls.

Ablation of amyloid precursor protein increases insulin-degrading enzyme levels and activity in brain and peripheral tissues.

The amyloid precursor protein (APP) is a type I transmembrane glycoprotein widely studied for its role as the source of β-amyloid peptide, accumulation of which is causal in at least some cases of Alzheimer's disease (AD). APP is expressed ubiquitously and is involved in diverse biological processes. Growing bodies of evidence indicate connections between AD and somatic metabolic disorders related to type 2 diabetes, and App mice show alterations in glycemic regulation.

Functional assessments through novel proteomics approaches: Application to insulin/IGF signaling in neurodegenerative disease'.

Background: Events that instigate disease may involve biochemical events distinct from changes in the steady-state levels of proteins. Even chronic degenerative disorders appear to involve changes such as post-translational modifications.

New Method: We have begun a series of proteomics analyses on proteins that have been fractionated by functional status.

Maternal obesity reprograms offspring's executive brain centers in a sex-specific manner?: An Editorial for 'Perinatal high fat diet and early life methyl donor supplementation alter one carbon metabolism and DNA methylation in the brain' on page 362.

This editorial highlights an article by McKee and colleagues in the current issue of Journal of Neurochemistry, in which the authors report epigenetic changes linked to one-carbon metabolism in prefrontal cortex (PFC) of murine offspring from dams fed high-fat diet to mimic maternal obesity. The group found that high-fat diet feeding in utero increases weight gain in offspring and dynamically alters DNA methylation in the PFC of male but not female brains. These epigenetic marks were associated with a shift in brain one-carbon metabolism (folate and methionine) intermediates and were normalized by early-life methyl-donor supplementation in a sex-specific manner.

Apolipoprotein E4 inhibits autophagy gene products through direct, specific binding to CLEAR motifs.

Introduction: Alzheimer apolipoprotein E (APOE) ɛ4/ɛ4 carriers have earlier disease onset and more protein aggregates than patients with other APOE genotypes. Autophagy opposes aggregation, and important autophagy genes are coordinately regulated by transcription factor EB (TFEB) binding to "coordinated lysosomal expression and regulation" (CLEAR) DNA motifs.

Methods: Autophagic gene expression was assessed in brains of controls and Alzheimer's disease (AD) patients parsed by APOE genotype and in a glioblastoma cell line expressing either apoE3 or apoE4.

Presenilin 1 mutations influence processing and trafficking of the ApoE receptor apoER2.

Presenilin (PS)-1 is an intramembrane protease serving as the catalytic component of γ-secretase. Mutations in the PS1 gene are the most common cause of familial Alzheimer's disease (FAD). The low-density lipoprotein (LDL)-receptor family member apoER2 is a γ-secretase substrate that has been associated with AD in several ways, including acting as a receptor for apolipoprotein E (ApoE).

Gene regulation and genetics in neurochemistry, past to future.

Ask any neuroscientist to name the most profound discoveries in the field in the past 60 years, and at or near the top of the list will be a phenomenon or technique related to genes and their expression. Indeed, our understanding of genetics and gene regulation has ushered in whole new systems of knowledge and new empirical approaches, many of which could not have even been imagined prior to the molecular biology boon of recent decades. Neurochemistry, in the classic sense, intersects with these concepts in the manifestation of neuropeptides, obviously dependent upon the central dogma (the established rules by which DNA sequence is eventually converted into protein primary structure) not only for their conformation but also for their levels and locales of expression.

Protein Kinases and Parkinson's Disease.

Currently, the lack of new drug candidates for the treatment of major neurological disorders such as Parkinson's disease has intensified the search for drugs that can be repurposed or repositioned for such treatment. Typically, the search focuses on drugs that have been approved and are used clinically for other indications. Kinase inhibitors represent a family of popular molecules for the treatment and prevention of various cancers, and have emerged as strong candidates for such repurposing because numerous serine/threonine and tyrosine kinases have been implicated in the pathobiology of Parkinson's disease.

Disrupted-in-schizophrenia-1 as a broader link of glutamatergic transmission to schizophrenia impacts cerebral neurochemistry via the production of the 'gliotransmitter' d-serine, a NMDA receptor coagonist.

This Editorial highlights a study by Xia and coworkers in the current issue of the Journal of Neurochemistry, in which the authors reveal a possible mechanistic link between DISC1 (disrupted-in-schizophrenia-1), a genetic risk factor for schizophrenia, and N-methyl-d-aspartate receptor (NMDAR) that is also linked with schizophrenia. The authors show that perturbed communication between DISC1 and NMDARs represents a hidden perpetrator for abnormal dendritic and synaptic maturation. Read the highlighted article 'DISC1, astrocytes and neuronal maturation: a possible mechanistic link with implications for mental disorders' on page 518.

Proteins that mediate protein aggregation and cytotoxicity distinguish Alzheimer's hippocampus from normal controls.

Neurodegenerative diseases are distinguished by characteristic protein aggregates initiated by disease-specific 'seed' proteins; however, roles of other co-aggregated proteins remain largely unexplored. Compact hippocampal aggregates were purified from Alzheimer's and control-subject pools using magnetic-bead immunoaffinity pulldowns. Their components were fractionated by electrophoretic mobility and analyzed by high-resolution proteomics.

A Role for P-Glycoprotein in Clearance of Alzheimer Amyloid β -Peptide from the Brain.

Most data indicates that Alzheimer's disease involves an accumulation of amyloid β - peptide (Aβ) in the CNS and that sporadic cases arise from a deficiency in Aβ clearance. Considerable attention has been given to mechanisms by which Aβ might be transported between the brain and blood, and evidence suggests that p-glycoprotein, also known as the multi-drug resistance (MDR) protein (product of the ABCB1 gene), plays a role in Aβ transport across the blood-brain barrier (BBB). We tested this possibility through two approaches: First, wild-type and MDR1A-knockout mice were compared after intravenous injection of [(125)I]-labeled Aβ; after 60 min, homogenates of brain parenchyma were subjected to γ-counting of TCA-precipitable material, and histological sections of brain were subjected to autoradiography.

Soluble amyloid precursor protein alpha inhibits tau phosphorylation through modulation of GSK3β signaling pathway.

We recently found that sAPPα decreases amyloid-beta generation by directly associating with β-site amyloid precursor protein (APP)-converting enzyme 1 (BACE1), thereby modulating APP processing. Because inhibition of BACE1 decreases glycogen synthase kinase 3 beta (GSK3β)-mediated Alzheimer's disease (AD)-like tau phosphorylation in AD patient-derived neurons, we determined whether sAPPα also reduces GSK3β-mediated tau phosphorylation. We initially found increased levels of inhibitory phosphorylation of GSK3β (Ser9) in primary neurons from sAPPα over-expressing mice.

Cycle on Wheels: Is APP Key to the AppBp1 Pathway?

Alzheimer's disease (AD) is the gradual loss of the cognitive function due to neuronal death. Currently no therapy is available to slow down, reverse or prevent the disease. Here we analyze the existing data in literature and hypothesize that the physiological function of the Amyloid Precursor Protein (APP) is activating the AppBp1 pathway and this function is gradually lost during the progression of AD pathogenesis.

Reductions of the components of the calreticulin/calnexin quality-control system by proteasome inhibitors and their relevance in a rodent model of Parkinson's disease.

Evidence indicates that the ubiquitin-proteasome system and the endoplasmic retculum (ER) quality-control system work in concert to ensure that proteins are correctly folded in the ER and that misfolded proteins are retrotransported to the cytosol for degradation by proteasomes. Dysfunction of either system results in developmental abnormalities and even death in animals. This study investigates whether and how proteasome inhibition impacts the components of the calreticulin (CRT)/calnexin (CNX) glycoprotein folding machinery, a typical ER protein quality-control system, in the context of early neuronal injury.