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Late Onset Alzheimer’s Disease is the most common cause of dementia, characterized by extracellular deposition of plaques primarily of amyloid-β (Aβ) peptide and tangles primarily of hyperphosphorylated tau protein. We present data to suggest a noninvasive strategy to decrease potentially toxic Aβ levels, using repeated electromagnetic field stimulation (REMFS) in primary human brain (PHB) cultures. We examined effects of REMFS on Aβ levels (Aβ40 and Aβ42, that are 40 or 42 amino acid residues in length, respectively) in PHB cultures at different frequencies, powers, and specific absorption rates (SAR). PHB cultures at day in vitro 7 (DIV7) treated with 64 MHz, and 1 hour daily for 14 days (DIV 21) had significantly reduced levels of secreted Aβ40 (p = 001) and Aβ42 (p = 0.029) peptides, compared to untreated cultures. PHB cultures (DIV7) treated at 64 MHz, for 1 or 2 hour during 14 days also produced significantly lower Aβ levels. PHB cultures (DIV28) treated with 64 MHz 1 hour/day during 4 or 8 days produced a similar significant reduction in Aβ40 levels. 0.4 W/kg was the minimum SAR required to produce a biological effect. Exposure did not result in cellular toxicity nor significant changes in secreted Aβ precursor protein-α (sAPPα) levels, suggesting the decrease in Aβ did not likely result from redirection toward the α-secretase pathway. EMF frequency and power used in our work is utilized in human magnetic resonance imaging (MRI, thus suggesting REMFS can be further developed in clinical settings to modulate Aβ deposition.

Fragile X mental retardation protein (FMRP) binds to and regulates the translation of amyloid-β protein precursor (App) mRNA, but the detailed mechanism remains to be determined. Differential methylation of App mRNA could underlie FMRP binding, message localization and translation efficiency. We sought to determine the role of FMRP and N6-methyladeonsine (m6A) on nuclear export of App mRNA. We utilized the m6A dataset by Hsu and colleagues to identify m6A sites in App mRNA and to determine if the abundance of message in the cytoplasm relative to the nucleus is altered in Fmr1 knockout mouse brain cortex. Given that processing of APP to Aβ and soluble APP alpha (sAPPα) contributes to disease phenotypes, we also investigated whether Fmr1KO associates with nuclear export of the mRNAs for APP protein processing enzymes, including β-site amyloid cleaving enzyme (Bace1), A disintegrin and metalloproteinases (Adams), and presenilins (Psen). Fmr1KO did not alter the nuclear/cytoplasmic abundance of App mRNA. Of 36 validated FMRP targets, 35 messages contained m6A peaks but only Agap2 mRNA was selectively enriched in Fmr1KO nucleus. The abundance of the APP processing enzymes Adam9 and Psen1 mRNA, which code for a minor alpha-secretase and gamma-secretase, respectively, were selectively enriched in wild type cytoplasm.

Rivastigmine (or Exelon) is a cholinesterase inhibitor, currently used as a symptomatic treatment for mild-to-moderate Alzheimer’s disease (AD). Amyloid-β peptide (Aβ) generated from its precursor protein (APP) by β-secretase (or BACE1) and γ-secretase endoproteolysis. Alternative APP cleavage by α-secretase (a family of membrane-bound metalloproteases– Adamalysins) precludes the generation of toxic Aβ and yields a neuroprotective and neurotrophic secreted sAPPα fragment. Several signal transduction pathways, including protein kinase C and MAP kinase, stimulate α-secretase. We present data to suggest that rivastigmine, in addition to anticholinesterase activity, directs APP processing away from BACE1 and towards α-secretases. We treated rat neuronal PC12 cells and primary human brain (PHB) cultures with rivastigmine and the α-secretase inhibitor TAPI and assayed for levels of APP processing products and α-secretases. We subsequently treated 3×Tg (transgenic) mice with rivastigmine and harvested hippocampi to assay for levels of APP processing products. We also assayed postmortem human control, AD, and AD brains from subjects treated with rivastigmine for levels of APP metabolites. Rivastigmine dose-dependently promoted α-secretase activity by upregulating levels of ADAM-9, -10, and -17 α-secretases in PHB cultures. Co-treatment with TAPI eliminated rivastigmine-induced sAPPα elevation. Rivastigmine treatment elevated levels of sAPPα in 3×Tg mice. Consistent with these results, we also found elevated sAPPα in postmortem brain samples from AD patients treated with rivastigmine. Rivastigmine can modify the levels of several shedding proteins and directs APP processing toward the non-amyloidogenic pathway. This novel property of rivastigmine can be therapeutically exploited for disease-modifying intervention that goes beyond symptomatic treatment for AD.

Background. The lead (Pb) exposure crisis in Flint, Michigan has passed from well-publicized event to a footnote, while its biological and social impact will linger for lifetimes. Interest in the “water crisis” has dropped to pre-event levels, which is neither appropriate nor safe. Flint’s exposure was severe, but it was not unique. Problematic Pb levels have also been found in schools and daycares in 42 states in the USA. The enormity of Pb exposure via municipal water systems requires multiple responses. Herein, we focus on addressing a possible answer to long-term sequelae of Pb exposure. We propose “4R’s” (remediation, renovation, reallocation, and research) against the Pb crisis that goes beyond a short-term fix. Remediation for affected individuals must continue to provide clean water and deal with both short and long-term effects of Pb exposure. Renovation of current water delivery systems, at both system-wide and individual site levels, is necessary. Reallocation of resources is needed to ensure these two responses occur and to get communities ready for potential sequelae of Pb exposure. Finally, properly focused research can track exposed individuals and illuminate latent (presumably epigenetic) results of Pb exposure and inform further resource reallocation. Conclusion. Motivation to act by not only the general public but also by scientific and medical leaders must be maintained beyond initial news cycle spikes and an annual follow-up story. Environmental impact of Pb contamination of drinking water goes beyond one exposure incident in an impoverished and forgotten Michigan city. Population effects must be addressed long-term and nationwide.

The multitude of molecular pathways underlying memory impairment in neurological disorders and aging-related disorders has been a major hurdle against therapeutic targeting. Over the years, neuronal growth promoting factors, intracellular kinases, and specific transcription factors, particularly cyclic AMP response element-binding protein (CREB), have emerged as crucial players of memory storage, and their disruption accompanies many cognitive disabilities. However, a molecular link that can influence these major players and can be a potential recovery target has been elusive. Recent reports suggest that extracellular cues at the synapses might evoke an intracellular signaling cascade and regulate memory function. Herein, we report novel function of an extracellular serine protease, kallikrein 8 (KLK8/Neuropsin) in regulating the expression of microtubule associated dendrite growth marker microtubule-associated protein (MAP2)c, dendrite architecture and protein kinase A (PKA)-CREB signaling. Both knockdown of KLK8 via siRNA transfection in mouse primary hippocampal neurons and via intra-hippocampal administration of KLK8 antisense oligonucleotides in vivo reduced expression of MAP2c, dendrite length, dendrite branching and spine density. The KLK8 mediated MAP2c deficiency in turn inactivated PKA and downstream transcription factor phosphorylated CREB (pCREB), leading to downregulation of memory-linked genes and consequent impaired memory consolidation. These findings revealed a protease associated novel pathway of memory impairment in which KLK8 may act as a “regulator of regulators”, suggesting its exploration as an important therapeutic target of memory disorders.

Lithium (Li) is a medication long-used to treat bipolar disorder. It is currently under investigation for multiple nervous system disorders, including Alzheimer’s disease (AD). While perturbation of RNA levels by Li has been previously reported, its effects on the whole transcriptome has been given little attention. We, therefore, sought to determine comprehensive effects of Li treatment on RNA levels. We cultured and differentiated human neuroblastoma (SK-N-SH) cells to neuronal cells with all-trans retinoic acid (ATRA). We exposed cultures for one week to lithium chloride or distilled water, extracted total RNA, depleted ribosomal RNA and performed whole-transcriptome RT-sequencing. We analyzed results by RNA length and type. We further analyzed expression and protein interaction networks between selected Li-altered protein-coding RNAs and common AD-associated gene products. Lithium changed expression of RNAs in both non-specific (inverse to sequence length) and specific (according to RNA type) fashions. The non-coding small nucleolar RNAs (snoRNAs) were subject to the greatest length-adjusted Li influence. When RNA length effects were taken into account, microRNAs as a group were significantly less likely to have had levels altered by Li treatment. Notably, several Li-influenced protein-coding RNAs were co-expressed or produced proteins that interacted with several common AD-associated genes and proteins. Lithium’s modification of RNA levels depends on both RNA length and type. Li activity on snoRNA levels may pertain to bipolar disorders while Li modification of protein coding RNAs may be relevant to AD.

Memory loss is one of the most tragic symptoms of Alzheimer’s disease. Our laboratory has recently demonstrated that ‘i-Extract’ of Ashwagandha (Withania somnifera) restores memory loss in scopolamine (SC)-induced mice. The prime target of i-Extract is obscure. We hypothesize that i-Extract may primarily target muscarinic subtype acetylcholine receptors that regulate memory processes. The present study elucidates key target(s) of i-Extract via cellular, biochemical, and molecular techniques in a relevant amnesia mouse model and primary hippocampal neuronal cultures. Wild type Swiss albino mice were fed i-Extract, and hippocampal cells from naïve mice were treated with i-Extract, followed by muscarinic antagonist (dicyclomine) and agonist (pilocarpine) treatments. We measured dendritic formation and growth by immunocytochemistry, kallikrein 8 (KLK8) mRNA by reverse transcription polymerase chain reaction (RT-PCR), and levels of KLK8 and microtubule-associated protein 2, c isoform (MAP2c) proteins by western blotting. We performed muscarinic receptor radioligand binding. i-Extract stimulated an increase in dendrite growth markers, KLK8 and MAP2. Scopolamine-mediated reduction was significantly reversed by i-Extract in mouse cerebral cortex and hippocampus. Our study identified muscarinic receptor as a key target of i-Extract, providing mechanistic evidence for its clinical application in neurodegenerative cognitive disorders.

Alzheimer’s disease (AD) is the most common age-related form of dementia, associated with deposition of intracellular neuronal tangles consisting primarily of hyperphosphorylated microtubule-associated protein tau (p-tau) and extracellular plaques primarily comprising amyloid- β (Aβ) peptide. The p-tau tangle unit is a posttranslational modification of normal tau protein. Aβ is a neurotoxic peptide excised from the amyloid-β precursor protein (APP) by β-site APP-cleaving enzyme 1 (BACE1) and the γ-secretase complex. MicroRNAs (miRNAs) are short, single-stranded RNAs that modulate protein expression as part of the RNA-induced silencing complex (RISC). We identified miR-298 as a repressor of APP, BACE1, and the two primary forms of Aβ (Aβ40 and Aβ42) in a primary human cell culture model. Further, we discovered a novel effect of miR-298 on posttranslational levels of two specific tau moieties. Notably, miR-298 significantly reduced levels of ~55 and 50 kDa forms of the tau protein without significant alterations of total tau or other forms. In vivo overexpression of human miR-298 resulted in nonsignificant reduction of APP, BACE1, and tau in mice. Moreover, we identified two miR-298 SNPs associated with higher cerebrospinal fluid (CSF) p-tau and lower CSF Aβ42 levels in a cohort of human AD patients. Finally, levels of miR-298 varied in postmortem human temporal lobe between AD patients and age-matched non-AD controls. Our results suggest that miR-298 may be a suitable target for AD therapy.

In addition to the devastating symptoms of dementia, Alzheimer’s disease (AD) is characterized by accumulation of the processing products of the amyloid-β (Aβ) peptide precursor protein (APP). APP’s non-pathogenic functions include regulating intracellular iron (Fe) homeostasis. MicroRNAs are small (~ 20 nucleotides) RNA species that instill specificity to the RNA-induced silencing complex (RISC). In most cases, RISC inhibits mRNA translation through the 3′-untranslated region (UTR) sequence. By contrast, we report a novel activity of miR-346: specifically, that it targets the APP mRNA 5′-UTR to upregulate APP translation and Aβ production. This upregulation is reduced but not eliminated by knockdown of argonaute 2. The target site for miR-346 overlaps with active sites for an iron-responsive element (IRE) and an interleukin-1 (IL-1) acute box element. IREs interact with iron response protein1 (IRP1), an iron-dependent translational repressor. In primary human brain cultures, miR-346 activity required chelation of Fe. In addition, miR-346 levels are altered in late-Braak stage AD. Thus, miR-346 plays a role in upregulation of APP in the CNS and participates in maintaining APP regulation of Fe, which is disrupted in late stages of AD. Further work will be necessary to integrate other metals, and IL-1 into the Fe-miR-346 activity network. We, thus, propose a “FeAR” (Fe, APP, RNA) nexus in the APP 5′-UTR that includes an overlapping miR-346-binding site and the APP IRE. When a “healthy FeAR” exists, activities of miR-346 and IRP/Fe interact to maintain APP homeostasis. Disruption of an element that targets the FeAR nexus would lead to pathogenic disruption of APP translation and protein production.

Late-onset Alzheimer's disease (LOAD) is the most common neurodegenerative disorder in older adults, affecting over 50% of those over age 85. Aging is the most important risk factor for the development of LOAD. Aging is associated with the decrease in the ability of cells to cope with cellular stress, especially protein aggregation. Here we describe how the process of aging affects pathways that control the processing and degradation of abnormal proteins including amyloid-β (Aβ). Genetic association studies in LOAD have successfully identified a large number of genetic variants involved in the development of the disease. However, there is a gap in understanding the interconnections between these pathomolecular events that prevent us from discovering therapeutic targets. We propose novel, pertinent links to elucidate how the biology of aging affects the sequence of events in the development of LOAD. Furthermore we analyze and synthesize the molecular-pathologic-clinical correlations of the aging process, involving the HSF1 and FOXO family pathways, Aβ metabolic pathway, and the different clinical stages of LOAD. Our new model postulates that the aging process would precede Aβ accumulation, and attenuation of HSF1 is an "upstream" event in the cascade that results in excess Aβ and synaptic dysfunction, which may lead to cognitive impairment and/or trigger "downstream" neurodegeneration and synaptic loss. Specific host factors, such as the activity of FOXO family pathways, would mediate the response to Aβ toxicity and the pace of progression toward the clinical manifestations of AD.

Autism spectrum disorder (ASD) and Fragile X syndrome (FXS) are developmental disorders. No validated blood-based biomarkers exist for either, which impedes bench-to-bedside approaches. Amyloid-β (Aβ) precursor protein (APP) and metabolites are usually associated with Alzheimer’s disease (AD). APP cleavage by α-secretase produces potentially neurotrophic secreted APPα (sAPPα) and the P3 peptide fragment. β-site APP cleaving enzyme (BACE1) cleavage produces secreted APPβ (sAPPβ) and intact Aβ. Excess Aβ is potentially neurotoxic and can lead to atrophy of brain regions such as amygdala in AD. By contrast, amygdala is enlarged in ASD but not FXS. We previously reported elevated levels of sAPPα in ASD and FXS vs. controls. We now report elevated plasma Aβ and total APP levels in FXS compared to both ASD and typically developing controls, and elevated levels of sAPPα in ASD and FXS vs. controls. By contrast, plasma and brain sAPPβ and Aβ were lower in ASD vs. controls but elevated in FXS plasma vs. controls. We also detected age-dependent increase in an α-secretase in ASD brains. We report a novel mechanistic difference in APP pathways between ASD (processing) and FXS (expression) leading to distinct APP metabolite profiles in these two disorders. These novel, distinctive biochemical differences between ASD and FXS pave the way for blood-based biomarkers for ASD and FXS.

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability and is associated with up to 5% of autism cases. Several promising drugs are in preclinical testing for FXS; however, bench-to-bedside plans for the clinic are severely limited due to lack of validated biomarkers and outcome measures. Published work from our laboratories has demonstrated altered levels of amyloid-beta (Aβ) precursor protein (APP) and its metabolites in FXS and idiopathic autism. Westmark and colleagues have focused on β-secretase (amyloidogenic) processing and the accumulation of Aβ peptides in adult FXS models, whereas Lahiri and Sokol have studied α-secretase (non-amyloidogenic or anabolic) processing and altered levels of sAPPα and Aβ in pediatric autism and FXS. Thus, our groups have hypothesized a pivotal role for these Alzheimer's disease (AD)-related proteins in the neurodevelopmental disorders of FXS and autism. In this review, we discuss the contribution of APP metabolites to FXS and autism pathogenesis as well as the potential use of these metabolites as blood-based biomarkers and therapeutic targets. Our future focus is to identify key underlying mechanisms through which APP metabolites contribute to FXS and autism condition-to-disease pathology. Positive outcomes will support utilizing APP metabolites as blood-based biomarkers in clinical trials as well as testing drugs that modulate APP processing as potential disease therapeutics. Our studies to understand the role of APP metabolites in developmental conditions such as FXS and autism are a quantum leap for the neuroscience field, which has traditionally restricted any role of APP to AD and aging.

Alzheimer's disease (AD) is the leading cause of dementia in the elderly. Extraneuronal plaque comprising mostly the amyloid β peptide and intraneuronal tangles of hyperphosphorylated microtubule-associated τ protein (τ, gene MAPT) are typical of AD. Misfolded τ is also implicated in Parkinson's disease and frontotemporal dementia. We aim to understand the regulation of the human MAPT promoter by mapping its functional domains. We subcloned a 4868 base pair (bp) fragment from human BAC RPCI-11 100C5. Sequence analysis revealed an H2 haplotype MAPT promoter, 5′-UTR, and intronal fragment. Database analysis of the fragment showed 50%–75% homology with mouse and > 90% with rhesus monkey. Comparison with human H1 sequences revealed differences that crossed predicted transcription factor sites. DNA-protein interaction studies by electrophoretic mobility shift assay suggested hypoxia response and an active specificity protein 1 (SP1) site in the 5′-untranslated region. Transfection of a series of MAPT promoter deletions revealed unique functional domains. The distal-most had different activities in neuronal vs. non-neuronal cells. We have cloned, sequenced, and functionally characterized a 4868 bp fragment of the human MAPT 5′-flanking region, including the core promoter region (− 302/+4), neurospecific domains (− 4364/−1992 and + 293/+504, relative to + 1 TSS), and a hypoxia-inducible element (+ 60/+84). Our work extended functional analysis of the MAPT sequence further upstream, and explores cell-type specificity of MAPT promoter activity. Finally, we provided direct comparison of likely transcription factor binding sites, which are useful to understand differences between H1/H2 pathogenic associations.

Deposition of extracellular plaques, primarily consisting of amyloid β peptide (Aβ), in the brain is the confirmatory diagnostic of Alzheimer's disease (AD); however, the physiological and pathological role of Aβ is not fully understood. Herein, we demonstrate novel Aβ activity as a putative transcription factor upon AD-associated genes. We used oligomers from 5'-flanking regions of the apolipoprotein E (APOE), Aβ-precursor protein (APP) and β-amyloid site cleaving enzyme-1 (BACE1) genes for electrophoretic mobility shift assay (EMSA) with different fragments of the Aβ peptide. Our results suggest that Aβ bound to an Aβ-interacting domain (AβID) with a consensus of "KGGRKTGGGG". This peptide-DNA interaction was sequence specific, and mutation of the first "G" of the decamer's terminal "GGGG" eliminated peptide-DNA interaction. Furthermore, the cytotoxic Aβ25-35 fragment had greatest DNA affinity. Such specificity of binding suggests that the AβID is worth of further investigation as a site wherein the Aβ peptide may act as a transcription factor.

The effects of amyloid-β are extremely complex. Current work in the field of Alzheimer disease is focusing on discerning the impact between the physiological signaling effects of soluble low molecular weight amyloid-β species, and the more global cellular damage that could derive from highly concentrated and/or aggregated amyloid. Being able to dissect the specific signaling events, to understand how soluble amyloid-β induces its own production by upregulating BACE1 expression, could lead to new tools to interrupt the distinctive feedback cycle with potential therapeutic consequences. Here we describe a positive loop that exists between the secretases that are responsible for the generation of the amyloid-β component of Alzheimer disease. According to our hypothesis, in familial Alzheimer disease, the primary overproduction of amyloid-β can induce BACE1 transcription and drive a further increase of amyloid-β precursor protein processing and resultant amyloid-β production. In sporadic Alzheimer disease, many factors, among them oxidative stress and inflammation, with consequent induction of presenilins and BACE1, would activate a loop and proceed with the generation of amyloid-β and its signaling role onto BACE1 transcription. This concept of a signaling effect by and feedback on the amyloid-β precursor protein will likely shed light on how amyloid-β generation, oxidative stress, and secretase functions are intimately related in sporadic Alzheimer disease.

The neurodegenerative disorder Alzheimer's disease (AD) is the 6th leading cause of death in the USA. In addition to neurological and psychiatric symptoms, AD is characterized by deficiencies in S-adenylmethionine (SAM), vitamin B12, and folate. Deficiency in these nutrients has been shown to result in gene promoter methylation with upregulation of AD-associated genes. While some cases of AD are due to specific mutations in genes such as presenilin 1 (PSEN) and the amyloid-beta peptide precursor protein (APP), these familial AD (FAD) cases account for a minority of cases. The majority of genetic contribution consists of risk factors with incomplete penetrance. Several environmental risk factors, such as cholesterol and diet, head trauma, and reduced levels of exercise, have also been determined for AD. Nevertheless, the majority of risk for AD appears to be established early in life. We propose to explain this via the LEARn (Latent Early-life Associated Regulation) model. LEARn-AD (LAD) would be a "two-hit" disorder, wherein the first hit would occur due to environmental stress within the regulatory sequences of AD-associated genes, maintained by epigenetic changes such as in DNA methylation. This hit would most likely come in early childhood. The second hit could consist of further stress, such as head trauma, poor mid-life diet, or even general changes in expression of genes that occur later in life independent of any pathogenesis. Given that the primary risk for LAD would be maintained by DNA (hypo)methylation, we propose that long-term nutritional remediation based on the LEARn model, or LEARn-based nutritional gain (LEARnING), beginning early in life, would significantly reduce risk for AD late in life.

Neurobiological disorders have diverse manifestations and symptomology. Neurodegenerative disorders, such as Alzheimer’s disease, manifest late in life and are characterized by, among other symptoms, progressive loss of synaptic markers. Developmental disorders, such as autism spectrum, appear in childhood. Neuropsychiatric and affective disorders, such as schizophrenia and major depressive disorder, respectively, have broad ranges of age of onset and symptoms. However, all share uncertain etiologies, with opaque relationships between genes and environment. We propose a ‘Latent Early-life Associated Regulation’ (LEARn) model, positing latent changes in expression of specific genes initially primed at the developmental stage of life. In this model, environmental agents epigenetically disturb gene regulation in a long-term manner, beginning at early developmental stages, but these perturbations might not have pathological results until significantly later in life. The LEARn model operates through the regulatory region (promoter) of the gene, specifically through changes in methylation and oxidation status within the promoter of specific genes. The LEARn model combines genetic and environmental risk factors in an epigenetic pathway to explain the etiology of the most common, that is, sporadic, forms of neurobiological disorders. Molecular Psychiatry (2009) 14, 992–1003; doi:10.1038/mp.2009.82

SummaryCyclin-dependent kinase 5 (cdk5) has been implicated in Alzheimer's disease (AD) pathogenesis. Here, we demonstrate that overexpression of p25, an activator of cdk5, led to increased levels of BACE1 mRNA and protein in vitro and in vivo. A p25/cdk5 responsive region containing multiple sites for signal transducer and activator of transcription (STAT1/3) was identified in the BACE1 promoter. STAT3 interacts with the BACE1 promoter, and p25-overexpressing mice had elevated levels of pSTAT3 and BACE1, whereas cdk5-deficient mice had reduced levels. Furthermore, mice with a targeted mutation in the STAT3 cdk5 responsive site had lower levels of BACE1. Increased BACE levels in p25 overexpressing mice correlated with enhanced amyloidogenic processing that could be reversed by a cdk5 inhibitor. These data demonstrate a pathway by which p25/cdk5 increases the amyloidogenic processing of APP through STAT3-mediated transcriptional control of BACE1 that could have implications for AD pathogenesis.

Alzheimer's disease is characterized by amyloid-beta peptide (Abeta)-loaded plaques in the brain. Abeta is a cleavage fragment of amyloid-beta protein precursor (APP) and over production of APP may lead to amyloidogenesis. The regulatory region of the APP gene contains consensus sites recognized by the transcription factor, specificity protein 1 (SP1), which has been shown to be required for the regulation of APP and Abeta. To understand the role of SP1 in APP biogenesis, herein we have characterized the relative distribution and localization of SP1, APP, and Abeta in various brain regions of rodent and primate models using immunohistochemistry. We observed that overall distribution and cellular localization of SP1, APP, and Abeta are similar and neuronal in origin. Their distribution is abundant in various layers of neocortex, but restricted to the Purkinje cell layer of the cerebellum, and the pyramidal cell layer of hippocampus. These findings suggest that overproduction of Abeta in vivo may be associated with transcriptional pathways involving SP1 and the APP gene.

Understanding of the pathophysiology of autism spectrum disorder (ASD) remains limited. Brain overgrowth has been hypothesized to be associated with the development of ASD. A derivative of amyloid-β precursor protein (APP), secreted APPα (sAPPα), has neuroproliferative effects and has been shown to be elevated in the plasma of persons with ASD compared to control subjects. Reduction in sAPPα holds promise as a novel molecular target of treatment in ASD. Research into the neurochemistry of ASD has repeatedly implicated excessive glutamatergic and deficient GABAergic neurotransmission in the disorder. With this in mind, acamprosate, a novel modulator of glutamate and GABA function, has been studied in ASD. No data is available on the impact of glutamate or GABA modulation on sAPPα function.Plasma APP derivative levels pre- and post-treatment with acamprosate were determined in two pilot studies involving youth with idiopathic and fragile X syndrome (FXS)-associated ASD. We additionally compared baseline APP derivative levels between youth with FXS-associated or idiopathic ASD.Acamprosate use was associated with a significant reduction in plasma sAPP(total) and sAPPα levels but no change occurred in Aβ40 or Aβ42 levels in 15 youth with ASD (mean age: 11.1 years). Youth with FXS-associated ASD (n = 12) showed increased sAPPα processing compared to age-, gender- and IQ-match youth with idiopathic ASD (n = 11).Plasma APP derivative analysis holds promise as a potential biomarker for use in ASD targeted treatment. Reduction in sAPP (total) and sAPPα may be a novel pharmacodynamic property of acamprosate. Future study is required to address limitations of the current study to determine if baseline APP derivative analysis may predict subgroups of persons with idiopathic or FXS-associated ASD who may respond best to acamprosate or to potentially other modulators of glutamate and/or GABA neurotransmission.

Alzheimer's disease (AD) is characterized by neuritic plaque formation, which is primarily composed of a small filamentous protein called amyloid-β peptide (Aβ). The rate-limiting step in the production of Aβ is the processing of Aβ precursor protein (APP) by a β-site APP-cleaving enzyme (BACE1). Hence, BACE1 activity plausibly plays a significant role in the generation of potentially toxic Aβ within brain and the development of AD, thereby making it an interesting drug target. A phase 2 trial of the promising LY2886721 inhibitor of BACE1 was suspended in June of 2013 by Eli Lilly and Company due to apparent liver toxicity. This outcome was apparently a surprise to the study's team, particularly since BACE1 knockout mice and mice treated with the drug did not show such liver toxicity. Lilly proposed that the problem was not due to LY2886721 anti-BACE1 activity. We offer an alternative hypothesis, whereby anti-BACE1 activity may induce apparent hepatotoxicity through inhibiting BACE1's processing of β-galactoside α-2,6-sialyltransferase I (STGal6 I). In knockout mice, paralogues, such as BACE2 or cathepsin D, could partially compensate. Furthermore, the short duration of animal studies and short lifespans of study animals could mask effects that would require several decades to accumulate in humans. Inhibition of hepatic BACE1 activity in middle-aged humans would produce effects not detectable in mice. In summary, we present a testable model to explain the off-target effects of LY2886721 and highlight more broadly that so called off-target drug effects might actually represent off-site effects that are not necessarily off-target. Consideration of this concept in forthcoming drug design, screening and testing programs might prevent such failures in the future.

The goal of genome-wide association studies is to identify SNPs unique to disease. It usually involves a single sampling from subjects’ lifetimes. While primary DNA sequence variation influences gene-expression levels, expression is also influenced by epigenetics, including the ‘somatic epitype’ (GSE), an epigenotype acquired postnatally. While genes are inherited, and novel polymorphisms do not routinely appear, GSE is fluid. Furthermore, GSE could respond to environmental factors (such as heavy metals) and to differences in exercise, maternal care and dietary supplements – all of which postnatally modify oxidation or methylation of DNA, leading to altered gene expression. Change in epigenetic status may be critical for the development of many diseases. We propose a ‘longitudinal epigenome-wide association study’, wherein GSE are measured at multiple time points along with subjects’ histories. This Longitudinal epigenome-wide association study, based on the ‘dynamic’ somatic epitype over the ‘static’ genotype, merits further investigation.

Amyloid-β peptide (Aβ) plaque in the brain is the primary (post mortem) diagnostic criterion of Alzheimer's disease (AD). The physiological role(s) of Aβ are poorly understood. We have previously determined an Aβ interacting domain (AβID) in the promoters of AD-associated genes (Maloney and Lahiri, 2011. Gene. 15,doi:10.1016/j.gene.2011.06.004. epub ahead of print.). This AβID interacts in a DNA sequence-specific manner with Aβ. We now demonstrate novel Aβ activity as a possible transcription factor. Herein, we detected Aβ–chromatin interaction in cell culture by ChIP assay. We observed that human neuroblastoma (SK–N–SH) cells treated with FITC conjugated Aβ1–40 localized Aβ to the nucleus in the presence of H2O2-mediated oxidative stress. Furthermore, primary rat fetal cerebrocortical cultures were transfected with APP and BACE1 promoter–luciferase fusions, and rat PC12 cultures were transfected with polymorphic APP promoter–CAT fusion clones. Transfected cells were treated with different Aβ peptides and/or H2O2. Aβ treatment of cell cultures produced a DNA sequence-specific response in cells transfected with polymorphic APP clones. Our results suggest the Aβ peptide may regulate its own production through feedback on its precursor protein and BACE1, leading to amyloidogenesis in AD.

Variations in levels of apolipoprotein E (ApoE) have been tied to the risk and progression of Alzheimer’s disease (AD). Our group has previously compared and contrasted the promoters of the mouse and human ApoE gene (APOE) promoter sequences and found notable similarities and significant differences that suggest the importance of the APOE promoter’s role in the human disease. We examine here three specific single–nucleotide polymorphisms within the human APOE promoter region, specifically at −219 (G/T), −427 (T/C), and at −491 (A/T) upstream from the +1 transcription start site. The −219 and −491 polymorphic variations have significant association with instance of AD, and −491AA has significant risk even when stratified for the APOEε4 allele. We also show significant effects on reporter gene expression in neuronal cell cultures, and, notably, these effects are modified by species origin of the cells. The −491 and −219 polymorphisms may have an interactive effect in addition to any independent activity. DNA–protein interactions differ between each polymorphic state. We propose SP1 and GATA as candidates for regulatory control of the −491 and −219 polymorphic sites. This work’s significance lies in drawing connection among APOE promoter polymorphisms’ associations with AD to functional promoter activity differences and specific changes in DNA–protein interactions with cell culture-based assays. Taken together, these results suggest that APOE expression levels are a risk factor for AD irrespective of APOEε4 allele status., This work was supported by the Alzheimer’s Association [to DKL]; National Institutes of Health [grant numbers AG18379, AG18884 to DKL]; and the Ministerio de Educación y Ciencia [grant number SAF2006-00724 to JP–T].

Alzheimer’s disease (AD), the most common form of dementia among the elderly, manifests mostly late in adult life. However, it is presently unclear when the disease process starts and how long the pathobiochemical processes take to develop. Our goal is to address the timing and nature of triggers that lead to AD. To explain the etiology of AD, we have recently proposed a “Latent Early-life Associated Regulation” (LEARn) model, which postulates a latent expression of specific genes triggered at the developmental stage. This model integrates both the neuropathological features (e.g., amyloid-loaded plaques and tau-laden tangles) and environmental factors (e.g., diet, metal exposure, and hormones) associated with the disease. Environmental agents perturb gene regulation in a long-term fashion, beginning at early developmental stages, but these perturbations do not have pathological results until significantly later in life. The LEARn model operates through the regulatory region (promoter) of the gene and by affecting the methylation status within the promoter of specific genes.

The sporadic nature of Alzheimer's disease (AD) argues for an environmental link that may drive AD pathogenesis; however, the triggering factors and the period of their action are unknown. Recent studies in rodents have shown that exposure to lead (Pb) during brain development predetermined the expression and regulation of the amyloid precursor protein (APP) and its amyloidogenic β-amyloid (Aβ) product in old age. Here, we report that the expression of AD-related genes [APP, BACE1 (β-site APP cleaving enzyme 1)] as well as their transcriptional regulator (Sp1) were elevated in aged (23-year-old) monkeys exposed to Pb as infants. Furthermore, developmental exposure to Pb altered the levels, characteristics, and intracellular distribution of Aβ staining and amyloid plaques in the frontal association cortex. These latent effects were accompanied by a decrease in DNA methyltransferase activity and higher levels of oxidative damage to DNA, indicating that epigenetic imprinting in early life influenced the expression of AD-related genes and promoted DNA damage and pathogenesis. These data suggest that AD pathogenesis is influenced by early life exposures and argue for both an environmental trigger and a developmental origin of AD.

Serotonin transporter promoter (5-HTTLPR) genotype appears to increase risk for depression in the context of stressful life events. However, the effects of this genotype on measures of stress sensitivity are poorly understood. Therefore, this study examined whether 5-HTTLPR genotype was associated with negative information processing biases in early childhood.Thirty-nine unselected seven-year-old children completed a negative mood induction procedure and a Self-Referent Encoding Task designed to measure positive and negative schematic processing. Children were also genotyped for the 5-HTTLPR gene.Children who were homozygous for the short allele of the 5-HTTLPR gene showed greater negative schematic processing following a negative mood prime than those with other genotypes. 5-HTTLPR genotype was not significantly associated with positive schematic processing.The sample size for this study was small. We did not analyze more recently reported variants of the 5-HTTLPR long alleles.5-HTTLPR genotype is associated with negative information processing styles following a negative mood prime in a non-clinical sample of young children. Such cognitive styles are thought to be activated in response to stressful life events, leading to depressive symptoms; thus, cognitive styles may index the "stress-sensitivity" conferred by this genotype.