Amyloid Beta Precursor Protein

Background: The pathogenesis of Alzheimer's disease (AD) is characterized by neuronal injury, activation of microglia and astrocytes, deposition of amyloid-β and secondary vessel degeneration. In the polycystic kidney disease (PKD) rat model, we observed neuronal injury, microglial activation and vasoregression. We speculated that this neuroretinal degeneration shares important pathogenetic steps with AD. Therefore, we determined the activation of astrocytes and the accumulation of amyloid-β in PKD retinae. Methods: Immunohistochemistry of PKD retinae for vimentin, carboxymethyllysin, beta-Amyloid 1-42, High-Mobility-Group-Protein B1 and amyloid protein precursor was performed. Results: Adjunct to astrocyte activation, accumulation of beta-Amyloid 1-42 and High-Mobility-Group-Protein B1 in astrocytes and around vessels of the superficial network was found in PKD retinae prior to the onset of vasoregression. Amyloid precursor protein was localized adjacent to the outer segment of photoreceptors in PKD and control rats. The parallel appearance of AD-related peptides indicates an alarmine based response to photoreceptor degeneration and secondary vasoregression. Conclusion: The model has broad overlap with AD and may be suitable to study beneficial pharmacological concepts.

Gastrodia elata (Tianma) is a traditional Chinese medicine often used for the treatment of headache, convulsions, hypertension, and cardiovascular diseases. The vasodilatory actions of Tianma led us to investigate its specific effects on memory and learning as well as on Alzheimer's disease (AD)-related signaling. We conducted a radial arm water maze analysis and the novel object recognition test to assess the cognitive functions of Tianma-treated mice. Our data show that Tianma enhances cognitive functions in mice. Further investigations revealed that Tianma enhances the α-secretase-mediated proteolytic processing of the amyloid precursor protein (App) that precludes the amyloid-β peptide production and supports the non-amyloidogenic processing of App which is favorable in AD treatment. We hypothesize that Tianma promotes cognitive functions and neuronal survival by inhibiting β-site App-cleaving enzyme 1 activity and promoting the neuroprotective α-secretase activity.

Objective One of the potent innate immune system stimulators is endotoxin or lipopolysaccharide (LPS). This stimulator can lead to systemic inflammatory response syndrome (SIRS). It may also ultimately lead to septic shock. Estrogen is a steroid hormone that plays an important role in female reproduction. This hormone also has multiple roles in other body systems, including the immune system. The aim of this study was to investigate the expression of TNF-α, IL-6, CCL2 and CCL3 genes in response to LPS. Other aims of this study were to evaluate histological and functional changes in the kidney and liver, measure serum levels of inflammatory cytokines such as TNF-α, IL-6 and MCP-1, and investigate the effects of ovariectomy (removal of the ovaries and consequently estrogen deficiency) on the extent of organ damage and inflammatory response induced by LPS in three-month-old adult female Wistar rats. Materials and methods Several groups would typically be included in an experiment to examine the effects of estrogen, endotoxins, and their combination. All laboratory tests for assessing inflammatory cytokines, kidney and liver function, and gene expression were carried out in the laboratories of the College

Synaptic transmission and long-term potentiation (LTP) in the CA1 region of hippocampal slices have been studied during ageing of a double transgenic mouse strain relevant to early-onset familial Alzheimer's disease (AD). This strain, which over-expresses both the 695 amino acid isoform of human amyloid precursor protein (APP) with K670N and M671L mutations and presenilin 1 with the A246E mutation, has accelerated amyloidosis and plaque formation. There was a decrease in synaptic transmission in both wildtype and transgenic mice between 2 and 9 months of age. However, preparing slices from 14 month old animals in kynurenic acid (1 mM) counteracted this age-related deficit. Basal transmission and paired-pulse facilitation was similar between the two groups at all ages (2, 6, 9 and 14 months) tested. Similarly, at all ages LTP, induced either by theta burst stimulation or by multiple tetani, was normal. These data show that a prolonged, substantially elevated level of Aβ are not sufficient to cause deficits in the induction or expression of LTP in the CA1 hippocampal region.

The metabolism of the amyloid precursor protein (APP) and tau are central to the pathobiology of Alzheimer's disease (AD). We have examined the in vivo turnover of APP, secreted APP (sAPP), Ab and tau in the wild-type and Tg2576 mouse brain using cycloheximide to block protein synthesis. In spite of overexpression of APP in the Tg2576 mouse, APP is rapidly degraded, similar to the rapid turnover of the endogenous protein in the wild-type mouse. sAPP is cleared from the brain more slowly, particularly in the Tg2576 model where the half-life of both the endogenous murine and transgene-derived human sAPP is nearly doubled compared to wild-type mice. The important Ab degrading enzymes neprilysin and IDE were found to be highly stable in the brain, and soluble Ab40 and Ab42 levels in both wild-type and Tg2576 mice rapidly declined following the depletion of APP. The cytoskeletal-associated protein tau was found to be highly stable in both wild-type and Tg2576 mice. Our findings unexpectedly show that of these various AD-relevant protein metabolites, sAPP turnover in the brain is the most different when comparing a wild-type mouse and a b-amyloid depositing, APP overexpressing transgenic model. Given the neurotrophic roles attributed to sAPP, the enhanced stability of sAPP in the b-amyloid depositing Tg2576 mice may represent a neuroprotective response.

Alzheimer's disease is a neurodegenerative disorder characterized by protein depositions in intracellular and extracellular spaces in the brain. The intraneuronal deposits are formed by neurofibrillary tangles composed mainly of abnormally phosphorylated tau, a microtubule-associated protein, whereas the major constituent of the amyloid deposited extracellularly in the brain parenchyma and vessel walls is amyloid beta-protein (A beta). The proteolytic processing of the beta-amyloid precursor protein (beta PP) results in the generation of a complex set of carboxyl-terminal peptides that contain A beta. In this study, we have used fusion proteins containing carboxyl-terminal fragments of beta PP to investigate the association of beta PP with cellular components. We demonstrate that specific domains within the carboxyl end of beta PP contain binding sites for cytoskeletal components; one, within residues 1 to 28 of A beta, binds directly to tubulin, and the second one, within sequences carboxyl-terminal to A beta, binds tau and tubulin. We propose that the two neuropathological hallmarks of Alzheimer's disease, A beta deposition and neurofibrillary tangles, represent the residual of a disrupted beta PP-tubulin-tau complex.

Background: Exosomes isolated in vitro contain full-length amyloid precursor protein (flAPP) and APP metabolites. Results: Exosomes secreted in vivo in brains of wild type and APP overexpressing mice contain higher levels of APP-CTFs relative to flAPP compared to brain-tissue. Conclusion: Brain exosomes are enriched with APP-CTFs. Significance: The exosome secretory pathway clears cellular APP-CTFs, releasing the toxic fragments into the neuropil.

Background Neurological outcomes of preterm infants with post-hemorrhagic hydrocephalus (PHH) remain among the worst in infancy, yet there remain few instruments to inform the treatment of PHH. We previously observed PHH-associated elevations in cerebrospinal fluid (CSF) amyloid precursor protein (APP), neural cell adhesion molecule-L1 (L1CAM), neural cell adhesion molecule-1 (NCAM-1), and other protein mediators of neurodevelopment. Objective The objective of this study was to examine the association of CSF APP, L1CAM, and NCAM-1 with ventricular size as an early step toward developing CSF markers of PHH. Methods CSF levels of APP, L1CAM, NCAM-1, and total protein (TP) were measured in 12 preterm infants undergoing PHH treatment. Ventricular size was determined using cranial ultrasounds. The relationships between CSF APP, L1CAM, and NCAM-1, occipitofrontal circumference (OFC), volume of CSF removed, and ventricular size were examined using correlation and regression analyses. Resul...

Leucine rich repeat transmembrane protein 3 (LRRTM3) is member of a synaptic protein family. LRRTM3 is a nested gene within a-T catenin (CTNNA3) and resides at the linkage peak for late-onset Alzheimer's disease (LOAD) risk and plasma amyloid b (Ab) levels. In-vitro knock-down of LRRTM3 was previously shown to decrease secreted Ab, although the mechanism of this is unclear. In SH-SY5Y cells overexpressing APP and transiently transfected with LRRTM3 alone or with BACE1, we showed that LRRTM3 co-localizes with both APP and BACE1 in early endosomes, where BACE1 processing of APP occurs. Additionally, LRRTM3 co-localizes with APP in primary neuronal cultures from Tg2576 mice transduced with LRRTM3expressing adeno-associated virus. Moreover, LRRTM3 co-immunoprecipitates with both endogenous APP and overexpressed BACE1, in HEK293T cells transfected with LRRTM3. SH-SY5Y cells with knock-down of LRRTM3 had lower BACE1 and higher CTNNA3 mRNA levels, but no change in APP. Brain mRNA levels of LRRTM3 showed significant correlations with BACE1, CTNNA3 and APP in ,400 humans, but not in LRRTM3 knock-out mice. Finally, we assessed 69 single nucleotide polymorphisms (SNPs) within and flanking LRRTM3 in 1,567 LOADs and 2,082 controls and identified 8 SNPs within a linkage disequilibrium block encompassing 59UTR-Intron 1 of LRRTM3 that formed multilocus genotypes (MLG) with suggestive global association with LOAD risk (p = 0.06), and significant individual MLGs. These 8 SNPs were genotyped in an independent series (1,258 LOADs and 718 controls) and had significant global and individual MLG associations in the combined dataset (p = 0.02-0.05). Collectively, these results suggest that protein interactions between LRRTM3, APP and BACE1, as well as complex associations between mRNA levels of LRRTM3, CTNNA3, APP and BACE1 in humans might influence APP metabolism and ultimately risk of AD.

Astrocytes play crucial roles in brain homeostasis and are emerging as regulatory elements of neuronal and synaptic physiology by responding to neurotransmitters with Ca 2+ elevations and releasing gliotransmitters that activate neuronal receptors. Ageing involves neuronal and astrocytic alterations, being considered risk factor for neurodegenerative diseases. Most evidence of the astrocyte-neuron signaling is derived from studies with young animals; however, the features of astrocyte-neuron signaling in adult and aging brain remain largely unknown. We have investigated the existence and properties of astrocyte-neuron signaling in physiologically and pathologically ageing mouse hippocampal and cortical slices at different lifetime points (0.5 to 20 month-old animals). We found that astrocytes preserved their ability to express spontaneous and neurotransmitter-dependent intracellular Ca 2+ signals from juvenile to ageing brains. Likewise, resting levels of gliotransmission, assessed by neuronal NMDAR activation by glutamate released from astrocytes, were largely preserved with similar properties in all tested age-groups, but DHPG-induced gliotransmission was reduced in aged mice. In contrast, gliotransmission was enhanced in the APP/PS1 mouse model of Alzheimer's disease, indicating a dysregulation of astrocyte-neuron signaling in pathological conditions. Disruption of the astrocytic IP 3 R2 mediated-signaling, which is required for neurotransmitter-induced astrocyte Ca 2+ signals and gliotransmission, boosted the progression of amyloid plaque deposits and synaptic plasticity impairments in APP/PS1 mice at early stages of the disease. Therefore, astrocyte-neuron interaction is a fundamental signaling, largely conserved in the adult and ageing brain of healthy †

The amyloid-␤ protein precursor/presenilin 1 (A␤PP/PS1) mouse model of Alzheimer's disease (AD) has provided robust neuropathological hallmarks of familial AD-like pattern. AD is a neurodegenerative process that causes severe cognitive impairment; it is characterized by the accumulation of amyloid-␤ (A␤) and hyperphosphorylated tau forms and by oxidative and inflammatory processes in brain. Currently, efforts are made to understand biochemical pathways because there is no effective therapy for AD. Resveratrol is a polyphenol that induces expression and activation of several neuroprotective pathways involving Sirtuin1 and AMPK. The objective of this work was to assess the effect of oral resveratrol administration on A␤PP/PS1 mice. Long-term resveratrol treatment significantly prevented memory loss as measured by the object recognition test. Moreover, resveratrol reduced the amyloid burden and increased mitochondrial complex IV protein levels in mouse brain. These protective effects of resveratrol were mainly mediated by increased activation of Sirtuin 1 and AMPK pathways in mice. However, an increase has been observed in IL1␤ and TNF gene expression, indicating that resveratrol promoted changes in inflammatory processes, although no changes were detected in other key actors of the oxidative stress pathway. Taken together, our findings suggest that resveratrol is able to reduce the harmful process that occurs in A␤PP/PS1 mouse hippocampus, preventing memory loss.

Several lines of biochemical evidence correlate the presence of energy metabolic defects with the functional alterations associated with brain aging and with the pathogenesis of neurodegenerative disorders such as Alzheimer's disease. Within this context we tested the ability of insulin to regulate the amyloid precursor protein (APP) processing in SH-SY5Y neuroblastoma cells. Our findings show that insulin promotes APP metabolism by a glucoseindependent mechanism. We demonstrate a novel intracellular pathway that increases the rate of secretion of soluble APP through the activity of phosphatidyl-inositol 3 kinase (PI3-K). This pathway, downstream of insulin receptor tyrosine kinase activity, does not involve either the activation of protein kinase C or the mitogen-activated protein kinase (MAP-K) pathway. Because of the physiological role of PI3-K in the translocation of glucose transportercontaining vesicles, we speculate that PI3-K involvement in APP metabolism may act at the level of vesicular trafficking.-

The amyloid precursor protein (APP) is a transmembrane protein mostly recognized for its association with Alzheimer's disease. The physiological function of APP is still not completely understood much because of the redundancy between genes in the APP family. In this study we have used zebrafish to study the physiological function of the zebrafish APP homologue, appb, during development. We show that appb is expressed in post-mitotic neurons in the spinal cord. Knockdown of appb by 50-60% results in a behavioral phenotype with increased spontaneous coiling and prolonged touch-induced activity. The spinal cord motor neurons in these embryos show defective formation and axonal outgrowth patterning. Reduction in Appb also results in patterning defects and changed density of pre-and post-synapses in the neuromuscular junctions. Together, our data show that development of functional locomotion in zebrafish depends on a critical role of Appb in the patterning of motor neurons and neuromuscular junctions.

The causes of phenotypic heterogeneity in familial Alzheimer's disease with autosomal dominant inheritance are not well understood. We aimed to characterise clinical phenotypes and genetic associations with APP and PSEN1 mutations in symptomatic autosomal dominant familial Alzheimer's disease (ADAD). We retrospectively analysed genotypic and phenotypic data (age at symptom onset, initial cognitive or behavioural symptoms, and presence of myoclonus, seizures, pyramidal signs, extrapyramidal signs, and cerebellar signs) from all individuals with ADAD due to APP or PSEN1 mutations seen at the Dementia Research Centre in London, UK. We examined the frequency of presenting symptoms and additional neurological features, investigated associations with age at symptom onset, APOE genotype, and mutation position, and explored phenotypic diff erences between APP and PSEN1 mutation carriers. The proportion of individuals presenting with various symptoms was analysed with descriptive statistics, stratifi ed by mutation type.

Numerous cytoplasmic adaptor proteins, including JIP1, FE65, and X11␣, affect amyloid precursor protein (APP) processing and A␤ production. Dab1 is another adaptor protein that interacts with APP as well as with members of the apoE receptor family. We examined the effect of Dab1 on APP and apoEr2 processing in transfected cells and primary neurons. Dab1 interacted with APP and apoEr2 and increased levels of their secreted extracellular domains and their cytoplasmic C-terminal fragments. These effects depended on the NPXY domains of APP and apoEr2 and on the phosphotyrosine binding domain of Dab1 but did not depend on phosphorylation of Dab1. Dab1 decreased the levels of APP ␤-C-terminal fragment and secreted A␤. Full-length Dab1 or its phosphotyrosine binding domain alone increased surface levels of APP, as determined by surface protein biotinylation and live cell staining. A ligand for apoEr2, the extracellular matrix protein Reelin, significantly increased the interaction of apoEr2 with Dab1. Surprisingly, we also found that Reelin treatment significantly increased the interaction of APP and Dab1. Moreover, Reelin treatment increased cleavage of APP and apoEr2 and decreased production of the ␤-C-terminal fragment of APP and A␤. Together, these data suggest that Dab1 alters trafficking and processing of APP and apoEr2, and this effect is influenced by extracellular ligands.

Alzheimer’s disease (AD) causes devastating cognitive impairment and an intense research effort is currently devoted to developing improved treatments for it. A minority of cases occur at a particularly young age and are caused by autosomal dominantly inherited genetic mutations. Although rare, familial AD provides unique opportunities to gain insights into the cascade of pathological events and how they relate to clinical manifestations. The phenotype of familial AD is highly variable and, although it shares many clinical features with sporadic AD, it also possesses important differences. Exploring the genetic and pathological basis of this phenotypic heterogeneity can illuminate aspects of the underlying disease mechanism, and is likely to inform our understanding and treatment of AD in the future.

In this study, we designed, synthesized, and evaluated a series of carbamate derivatives of N-salicyloyl tryptamine as multifunctional therapeutic agents for the treatment of Alzheimer's disease (AD). After screening the acetylcholinesterase (AChE)/butyrylcholinesterase (BChE) inhibitory activities, target compound 1g stood out as a mixed type reversible dual inhibitor of AChE and BChE. In addition, molecular docking studies were conducted to explore the actions on AChE and BChE. The results showed that 1g could decrease the level of pro-inflammatory cytokines NO, iNOS, IL-6, TNF-a, and ROS, increase the level of anti-inflammatory cytokines IL-4, and inhibit the aggregation of Ab 1-42. Moreover, the administration of 1g suppressed the activity of AChE in the brain. In a word, the compound 1g is effective for improving learning and memory behavior, blood-brain barrier permeation, pharmacokinetics, ChE inhibition, and anti-neuroinflammation. It may be considered as a promising multi-functional therapeutic agent for further investigation for the treatment of AD.

According to epidemiological studies, type-2 diabetes increases the risk of Alzheimer's disease. Here, we induced hyperglycaemia in mice overexpressing mutant amyloid precursor protein and presenilin-1 (APdE9) either by cross-breeding them with pancreatic insulinlike growth factor 2 (IGF-2) overexpressing mice or by feeding them with high-fat diet. Glucose and insulin tolerance tests revealed significant hyperglycaemia in mice overexpressing IGF-2, which was exacerbated by high-fat diet. However, sustained hyperinsulinaemia and insulin resistance were observed only in mice co-expressing IGF-2 and APdE9 without correlation to insulin levels in brain. In behavioural tests in aged mice, APdE9 was associated with poor spatial learning and the combination of IGF-2 and high-fat diet further impaired learning. Neither high-fat diet nor IGF-2 increased ␤-amyloid burden in the brain. In male mice, IGF-2 increased ␤-amyloid 42/40 ratio, which correlated with poor spatial learning. In contrast, inhibitory phosphorylation of glycogen synthase kinase 3␤, which correlated with good spatial learning, was increased in APdE9 and IGF-2 female mice on standard diet, but not on high-fat diet. Interestingly, high-fat diet altered isoform expression and increased phosphorylation of at Ser202 site in female mice regardless of genotype. These findings provide evidence for new regulatory mechanisms that link type-2 diabetes and Alzheimer pathology.

Inhibiting β-amyloid aggregation and enhancing its clearance are the key strategies in Alzheimer's disease (AD) treatment. Liver X receptors (LXRs) plays a crucial role in cholesterol homeostasis and inflammation, and their activation can clear Aβ aggregates in AD. Allopregnanolone, a neurosteroid, positively influences AD through LXR regulation, while ganaxolone, its synthetic analog, is known for its neuroprotective properties. This study explores the effect of ganaxolone on LXR activation and regulation of genes involved in mitigating Aβ toxicity and tauopathy in SH-SY5Y cells transfected with APP695 Swe/Ind plasmid and an Aβ1-42 induced AD mouse model. Molecular docking stimulations indicated ganaxolone's binding and interaction with LXRβ. Subsequently, transfected neuronal cells exhibited increased mRNA levels of APP, TNF-α and IL-1β, decreased cell viability, reduced MMP and altered protein expression of Aβ, LXR, BCL-2, APOE, ABCA1, along with increased levels of mROS, Bax, and caspase 3 activity. Ganaxolone treatment significantly abrogated Aβ-induced effect in transfected neuronal cells by enhancing LXRβ expression, inducing LXR:RXR colocalization, thereby increasing APOE and ABCA1 expression. It also decreased tau mRNA levels in transfected cells. Importantly, in AD mice, ganaxolone ameliorated cognitive impairment, reduced Aβ toxicity, tau levels, and neuroinflammatory markers, restored mitochondrial function, and decreased neuronal apoptosis. Taken together, these novel results highlight the central role of LXR in mediating Aβ-induced toxicity and provide preclinical evidence for ganaxolone as a potential agent to reduce toxicity in an LXR-dependent manner. This may serve as a promising treatment strategy to slow or prevent neurodegeneration in AD patients.

Elevated levels of β-site APP cleaving enzyme 1 (BACE1) were found in the brain of some sporadic Alzheimer's disease (AD) patients; however, the underlying mechanism is unknown. BACE1 cleaves β-amyloid precursor protein (APP) to generate amyloid β protein (Aβ), a central component of neuritic plaques in AD brains. Nuclear factor-kappa B (NF-κB) signalling plays an important role in gene regulation and is implicated in inflammation, oxidative stress and apoptosis. In this report we found that both BACE1 and NF-κB p65 levels were significantly increased in the brains of AD patients. Two functional NF-κB-binding elements were identified in the human BACE1 promoter region. We found that NF-κB p65 expression resulted in increased BACE1 promoter activity and BACE1 transcription, while disruption of NF-κB p65 decreased BACE1 gene expression in p65 knockout (RelA-knockout) cells. In addition, NF-κB p65 expression leads to up-regulated β-secretase cleavage and Aβ production, while non-st...

The cognitive impairment in patients with Alzheimer's disease is closely associated with synaptic loss in the neocortex and limbic system. Although the neurotoxic effects of aggregated amyloid-β (Aβ) oligomers in Alzheimer's disease have been widely studied in experimental models, less is known about the characteristics of these aggregates across the spectrum of Alzheimer's disease. Here, postmortem frontal cortex samples from control and Alzheimer's disease patients were fractioned and analyzed for levels of oligomers and synaptic proteins. We found that levels of oligomers correlated with the severity of cognitive impairment (Blessed score and Mini-Mental), and with the loss of synaptic markers. Reduced levels of the synaptic vesicle protein vesicleassociated membrane protein-2 and the postsynaptic protein post-synaptic density-95 (PSD95) correlated with levels of oligomers in the various fractions analyzed. The strongest associations were found with Aβ dimers and pentamers. Co-immunoprecipitation and double-labeling experiments support the possibility that Aβ and PSD95 interact at the synaptic sites. Similarly, in transgenic mice expressing high levels of neuronal amyloid precursor protein (APP), Aβ coimmunoprecipitated with PSD95. This was accompanied by a reduction in the levels of the postsynaptic proteins Shank1 and 3 in Alzheimer's disease patients and in the brains of APP transgenic mice. In conclusion, this study suggests that the presence of a subpopulation of Aβ oligomers in the brains of patients with Alzheimer's disease might be related to alterations in selected synaptic proteins and cognitive impairment.

A novel cleavage of β-amyloid precursor protein (APP), referred to as ϵ-cleavage, occurs downstream of the γ-cleavage and generates predominantly a C-terminal fragment (CTFγ) that begins at Val-50, according to amyloid β-protein (Aβ) numbering. Whether this cleavage occurs independently of, or is coordinated with, γ-cleavage is unknown. Using a cell-free system, we show here that, although Aβ40 and CTFγ 50–99 were the predominant species produced by membranes prepared from cells overexpressing wild-type (wt) APP and wt presenilin (PS) 1 or 2, the production of CTFγ 49–99, which begins at Leu-49, was remarkably enhanced in membranes from cells overexpressing mutant (mt) APP or mtPS1/2 that increases the production of Aβ42. Furthermore, a γ-secretase inhibitor, which suppresses Aβ40 production and paradoxically enhances Aβ42 production at low concentrations, caused the proportion of CTFγ 50–99 to decrease and that of CTFγ 49–99 to increase significantly. These results strongly suggest...

Three peptide segments corresponding to the extracellular domain of a human sperm protein designated as YWK-II antigen were synthesized as multiple antigen peptide (MAP). Male and female rats were immunized with the YWK-II-MAPS and fertility determined. In a group of 12 female rats immunized with YAL-198, seven animals were infertile and two animals were subfertile. When immunized with YAL-201 and YAL-212, 4 and 2 animals were infertile, respectively. In a group of 15 males immunized with YAL-1982 animals were infertile and 6 were subfertile. Two animals immunized with YAL-201 were subfertile. All control male and female rats immunized with bovine serum albumin and adjuvant were fertile. Sera obtained from infertile rats immunized with YAL-198 contained higher titers of antibodies compared to those obtained from fertile animals. The present study shows that immunization with synthetic peptide segments of a sperm protein can effectively reduce fertility. a 1992 ?.ca&?mrc pre**, 1°C. Infertility of undetermined etiology is a clinical entity of considerable magnitude that requires resolution (1). "Immunologic infertility" is due to the production of antigamete antibodies, derangement of B and/or T cell activities in the reproductive tract or alteration in the functional components of the immune network (2-6). There is a consensus that antisperm antibodies with sperm agglutinating and/or immobilizing activities may be a probable cause of infertility; however, direct experimental verification of this thesis is lacking. There are studies supporting this contention. For example, immunization of animals with sperm, sperm extracts or purified sperm proteins will result in a marked reduction of fertility, suggesting that production of antispenn antibodies can reduce fertility or induce infertility (7-14). To validate that antisperm antibodies with sperm agglutinating activity is a cause of infertility, we have raised monoclonal antibodies (mAb) against specific human sperm proteins with sperm agglutinating activity (15-17). One of the antisperm mAb designated *To whom correspondence should be addressed.

Alzheimer's disease (AD) poses a serious public health threat to the United States. Disease modifying drugs slowing AD progression are in urgent need, yet are still unavailable. According to the amyloid cascade hypothesis, inhibition of beta or gamma secretase, key enzymes for the production of beta amyloid (Aβ), may be viable mechanisms for the treatment of AD. For discovery of gamma secretase inhibitors (GSIs), the APP overexpressing Tg2576 mouse has been the preclinical model of choice, in part due to the ease of detection of Aβ species in its brain, plasma, and cerebrospinal fluid (CSF). Some biological observations and practical considerations, however, argue against the use of the Tg2576 mouse. We reasoned that an animal model would be suitable for GSI discovery if the PK/PD relationship of a compound for Aβ lowering in this model is predictive of that in human. In this study, we assessed whether the background 129/SVE strain is a suitable preclinical pharmacology model for identifying new GSIs by evaluating the translatability of the intrinsic PK/PD relationships for brain and CSF Aβ across the Tg2576 and 129/SVE mouse and human. Using semi-mechanistically based PK/PD modeling, our analyses indicated that the intrinsic PK/PD relationship for brain Aβx-42 and CSF Aβx-40 in the 129/SVE mouse is indicative of that for human CSF Aβ. This result, in conjunction with practical considerations, strongly suggests that the 129/SVE mouse is a suitable model for GSI discovery. Concurrently, the necessity and utilities of PK/PD modeling for rational interpretation of Aβ data is established.

The accumulation of amyloid-β (Aβ) as amyloid fibrils and toxic oligomers is an important step in the development of Alzheimer's disease (AD). However, there are numerous potentially toxic oligomers and little is known about their neurological effects when generated in the living brain.

We quantified the amount of amyloid β-peptide (Aβ) immunoreactivity as well as amyloid deposits in a large cohort of transgenic mice overexpressing the V717F human amyloid precursor protein ( APP V717F+/− TG mice) with no, one, or two mouse apolipoprotein E ( Apoe ) alleles at various ages. Remarkably, no amyloid deposits were found in any brain region of APP V717F+/− Apoe −/− TG mice as old as 22 mo of age, whereas age-matched APP V717F +/− Apoe +/− and Apoe +/+ TG mice display abundant amyloid deposition. The amount of Aβ immunoreactivity in the hippocampus was also markedly reduced in an Apoe gene dose-dependent manner ( Apoe +/+ > Apoe +/− ≫ Apoe −/− ), and no Aβ immunoreactivity was detected in the cerebral cortex of APP V717F+/− Apoe −/− TG mice at any of the time points examined. The absence of apolipoprotein E protein (apoE) dramatically reduced the amount of both Aβ 1–40 and Aβ 1–42 immunoreactive deposits as well as the resulting astrogliosis and microgliosis normally o...

The ␤-amyloid precursor protein (APP) represents a type I transmembrane glycoprotein that is ubiquitously expressed. In the brain, it is a key player in the molecular pathogenesis of Alzheimer disease. Its physiological function is however less well understood. Previous studies showed that APP is up-regulated in prostate, colon, pancreatic tumor, and oral squamous cell carcinoma. In this study, we show that APP has an essential role in growth control of pancreatic and colon cancer. Abundant APP staining was found in human pancreatic adenocarcinoma and colon cancer tissue. Interestingly, treating pancreatic and colon cancer cells with valproic acid (VPA, 2-propylpentanoic acid), a known histone deacetylase (HDAC) inhibitor, leads to up-regulation of GRP78, an endoplasmic reticulum chaperone immunoglobulin-binding protein. GRP78 is involved in APP maturation and inhibition of tumor cell growth by down-regulation of APP and secreted soluble APP␣. Trichostatin A, a pan-HDAC inhibitor, also lowered APP and increased GRP78 levels. In contrast, treating cells with valpromide, a VPA derivative lacking HDAC inhibitory properties, had no effect on APP levels. VPA did not modify the level of epidermal growth factor receptor, another type I transmembrane protein, and APLP2, a member of the APP family, demonstrating the specificity of the VPA effect on APP. Small interfering RNA-mediated knockdown of APP also resulted in significantly decreased cell growth. Based on these observations, the data suggest that APP downregulation via HDAC inhibition provides a novel mechanism for pancreatic and colon cancer therapy.

The disaccharide trehalose is commonly considered to stimulate autophagy. Cell treatment with trehalose could decrease cytosolic aggregates of potentially pathogenic proteins, including mutant huntingtin, alpha-synuclein and phosphorylated tau that are associated with neurodegenerative diseases. Here, we demonstrate that trehalose also alters the metabolism of the Alzheimer related amyloid precursor protein (APP). Cell treatment with trehalose decreased the degradation of full-length APP and its C-terminal fragments (CTFs). Trehalose also reduced the secretion of the amyloid β-peptide. Biochemical and cell biological experiments revealed that trehalose alters the subcellular distribution and decreases the degradation of APP-CTFs in endolysosomal compartments. Trehalose also led to strong accumulation of the autophagic marker proteins LC3-II and p62, and decreased the proteolytic activation of the lysosomal hydrolase cathepsin D. The combined data indicate that trehalose decreases th...

The ␤-amyloid precursor protein (APP) represents a type I transmembrane glycoprotein that is ubiquitously expressed. In the brain, it is a key player in the molecular pathogenesis of Alzheimer disease. Its physiological function is however less well understood. Previous studies showed that APP is up-regulated in prostate, colon, pancreatic tumor, and oral squamous cell carcinoma. In this study, we show that APP has an essential role in growth control of pancreatic and colon cancer. Abundant APP staining was found in human pancreatic adenocarcinoma and colon cancer tissue. Interestingly, treating pancreatic and colon cancer cells with valproic acid (VPA, 2-propylpentanoic acid), a known histone deacetylase (HDAC) inhibitor, leads to up-regulation of GRP78, an endoplasmic reticulum chaperone immunoglobulin-binding protein. GRP78 is involved in APP maturation and inhibition of tumor cell growth by down-regulation of APP and secreted soluble APP␣. Trichostatin A, a pan-HDAC inhibitor, also lowered APP and increased GRP78 levels. In contrast, treating cells with valpromide, a VPA derivative lacking HDAC inhibitory properties, had no effect on APP levels. VPA did not modify the level of epidermal growth factor receptor, another type I transmembrane protein, and APLP2, a member of the APP family, demonstrating the specificity of the VPA effect on APP. Small interfering RNA-mediated knockdown of APP also resulted in significantly decreased cell growth. Based on these observations, the data suggest that APP downregulation via HDAC inhibition provides a novel mechanism for pancreatic and colon cancer therapy.

The human β-amyloid (Aβ) cleaving enzyme (BACE-1) is a target for Alzheimer's disease (AD) treatments. This study was conducted to determine if acacetin extracted from the whole Agastache rugosa plant had anti-BACE-1 and behavioral activities in Drosophila melanogaster AD models and to determine acacetin's mechanism of action. Acacetin (100, 300, and 500 μM) rescued amyloid precursor protein (APP)/BACE1-expressing flies and kept them from developing both eye morphology (dark deposits, ommatidial collapse and fusion, and the absence of ommatidial bristles) and behavioral (motor abnormalities) defects. The reverse transcription polymerase chain reaction analysis revealed that acacetin reduced both the human APP and BACE-1 mRNA levels in the transgenic flies, suggesting that it plays an important role in the transcriptional regulation of human BACE-1 and APP. Western blot analysis revealed that acacetin reduced Aβ production by interfering with BACE-1 activity and APP synthesis...

Amyloid beta/A4 protein precursor (APP) is secreted into medium by most cultured cells and can function as an autocrine factor. To study the biological function of secreted forms of APP (sAPP) on neurons, we used a clonal CNS neuronal line, B103, which does not synthesize detectable levels of APP. B103 cells transfected with APP construct developed neurites faster than the parent B103 cells when plated in a serum-free defined medium. Neurite outgrowth of B103 cells was promoted by the conditioned medium of APP-695-over-producing cells or by the bacteria- produced sAPP-695 (named KB75). A series of peptides having sequences between Ala-319 and Met-335 of APP-695 also stimulated neurite outgrowth of B103 cells. The sequence of five amino acids, RERMS (APP 328–332), within this stretch of sequence, was the shortest active peptide, although the concentration required for the neuritotropic activity was higher than that of KB75. Binding assay using 125I-labeled APP 17-mer peptide correspo...

Diet is a modifiable risk factor for Alzheimer's disease (AD), but the mechanisms linking alterations in peripheral metabolism and cognition remain unclear. Since it is especially difficult to study long-term effects of high-energy diet in individuals at risk for AD, we addressed this question by using the McGill-R-Thy1-APP transgenic rat model (Tg(+/-)) that mimics presymptomatic AD. Wild-type and Tg(+/-) rats were exposed during 6months to a standard diet or a Western diet (WD), high in saturated fat and sugar. Results from peripheral and hippocampal biochemical analysis and in situ respirometry showed that WD induced a metabolic syndrome and decreased presynaptic bioenergetic parameters without alterations in hippocampal insulin signaling or lipid composition. Cognitive tests, ELISA multiplex, Western blot, immunohistochemistry and RT-qPCR indicated that WD worsened cognition in Tg(+/-) rats, increased hippocampal levels of monomeric Aβ isoforms and oligomeric species, promot...

In Alzheimer's disease (AD), numerous β-amyloid (Aβ) plaques are associated with butyrylcholinesterase (BChE) activity, the significance of which is unclear. A mouse model, containing five human familial AD genes (5XFAD), also develops Aβ plaques with BChE activity. Knock-out of BChE in this model showed diminished fibrillar Aβ plaque deposition, more so in males than females. This suggests that lack of BChE reduces deposition of fibrillar Aβ in AD and this effect may be influenced by sex.

Brain glucose hypometabolism has been observed in Alzheimer's disease (AD) patients, and is detected with 18 F radiolabelled glucose, using positron emission tomography. A pathological hallmark of AD is deposition of brainamyloid plaques that may influence cerebral glucose metabolism. The five times familial AD (5XFAD) mouse is a model of brain amyloidosis exhibiting AD-like phenotypes. This study examines brain -amyloid plaque deposition and 18 FDG uptake, to search for an early biomarker distinguishing 5XFAD from wild-type mice. Thus, brain 18 FDG uptake and plaque deposition was studied in these mice at age 2, 5 and 13 months. The 5XFAD mice demonstrated significantly reduced brain 18 FDG uptake at 13 months relative to wild-type controls but not in younger mice, despite substantialamyloid plaque deposition. However, by comparing the ratio of uptake values for glucose in different regions in the same brain, 5XFAD mice could be distinguished from controls at age 2 months. This method of measuring altered glucose metabolism may represent an early biomarker for the progression of amyloid deposition in the brain. We conclude that brain 18 FDG uptake can be a sensitive biomarker for early detection of abnormal metabolism in the 5XFAD mouse when alternative relative uptake values are utilized.

Histochemical analysis of Alzheimer disease (AD) brain tissues indicates that butyrylcholinesterase (BuChE) is present in A-amyloid (AA) plaques. The role of BuChE in AD pathology is unknown, but an animal model developing similar BuChE-associated AA plaques could provide insights. The APP SWE /PSEN1dE9 transgenic mouse (ADTg), which develops AA plaques, was examined to determine if BuChE associates with these plaques, as in AD. We found that in mature ADTg mice, BuChE activity associated with AA plaques. The AA-, thioflavin-SY and BuChE-positive plaques mainly accumulated in the olfactory structures, cerebral cortex, hippocampal formation, amygdala, and cerebellum. No plaques were stained for acetylcholinesterase activity. The distribution and abundance of plaque staining in ADTg closely resembled many aspects of plaque staining in AD. Butyrylcholinesterase staining consistently showed fewer plaques than were detected with AA immunostaining but a greater number of plaques than were visualized with thioflavin-S. Double-labeling experiments demonstrated that all BuChE-positive plaques were AA positive, whereas only some BuChE-positive plaques were thioflavin-S positive. These observations suggest that BuChE is associated with a subpopulation of AA plaques and may play a role in AD plaque maturation. A further study of this animal model could clarify the role of BuChE in AD pathology.

We examined the effect of amyloid-β (Aβ) peptide, the main component of the senile plaques playing a critical role in the deregulation of calcium (Ca 2+ ) homeostasis in AD, on the circadian oscillation of cytosolic calcium (Ca 2+ ) levels in vitro. The experiments we carried out in human primary skin fibroblasts. This cell line was previously shown to exhibit circadian rhythms of clock genes. Moreover, the basic clock properties of these peripheral cells closely mimic those measured physiologically and behaviorally in human and do not change during aging. In this study we showed that i) cytosolic Ca 2+ oscillations depend on the activation of purinergic P2X7 receptors; and ii) these oscillations are abolished in the presence of Aβ. In total, our new findings may help to deepen our understanding of the molecular mechanisms involved in AD-related circadian alterations.

Presenilin is the enzymatic component of γ-secretase, a multisubunit intramembrane protease that processes several transmembrane receptors, such as the amyloid precursor protein (APP). Mutations in human Presenilins lead to altered APP cleavage and early-onset Alzheimer's disease. Presenilins also play an essential role in Notch receptor cleavage and signaling. The Notch pathway is a highly conserved signaling pathway that functions during the development of multicellular organisms, including vertebrates, Drosophila, and C. elegans. Recent studies have shown that Notch signaling is sensitive to perturbations in subcellular trafficking, although the specific mechanisms are largely unknown. To identify genes that regulate Notch pathway function, we have performed two genetic screens in Drosophila for modifiers of Presenilin-dependent Notch phenotypes. We describe here the cloning and identification of 19 modifiers, including nicastrin and several genes with previously undescribed ...

This study points out different behaviour between HEK cells overexpressing wild-type or mutant APP when exposed to oxidative insult. Although apparently both APPwt and APPmut overexpression conferred resistance to oxidative insult, some differences in terms of degree of protection was observed in the two clones. We found that the two clones differed, especially, in terms of redox profile. HEK-APPmut cells were characterized by higher levels of oxidative markers in comparison with HEK-APPwt. In addition, SOD activity appeared more efficient in HEK-APPwt than in HEK-APPmut, thus justifying the differences in terms of cell survival in the two clones. We suggest that, according to ''hormesis theory'', in HEK-APPwt cells low amount of oxidative stress can exert a beneficial effect that at a higher intensity results harmful. In contrast, HEK-APPmut cells lost this stress resistance probably because the degree of oxidative stress is too high and the antioxidant enzymes are themselves compromised.

Gliosis is a pathological hallmark of posttraumatic epileptic foci, but little is known about these reactive astrocytes beyond their high glial fibrillary acidic protein (GFAP) expression. Using diolistic labeling, we show that cortical astrocytes lost their nonoverlapping domain organization in three mouse models of epilepsy: posttraumatic injury, genetic susceptibility, and systemic kainate exposure. Neighboring astrocytes in epileptic mice showed a 10-fold increase in overlap of processes. Concurrently, spine density was increased on dendrites of excitatory neurons. Suppression of seizures by the common antiepileptic, valproate, reduced the overlap of astrocytic processes. Astrocytic domain organization was also preserved in APP transgenic mice expressing a mutant variant of human amyloid precursor protein despite a marked upregulation of GFAP. Our data suggest that loss of astrocytic domains was not universally associated with gliosis, but restricted to seizure pathologies. Reor...

Various compounds that affect signal transduction regulate the relative utilization of alternative processing pathways for the beta-amyloid precursor protein (beta APP) in intact cells, increasing the production of nonamyloidogenic soluble beta APP (s beta APP) and decreasing that of amyloidogenic beta-amyloid peptide. In a recent study directed toward elucidating the mechanisms underlying phorbol ester-stimulated s beta APP secretion from cells, it was demonstrated that protein kinase C increases the formation from the trans-Golgi network (TGN) of beta APP-containing secretory vesicles. Here we present evidence that forskolin increases s beta APP production from intact PC12 cells, and protein kinase A stimulates formation from the TGN of beta APP-containing vesicles. Although protein kinase A and protein kinase C converge at the level of formation from the TGN of beta APP-containing vesicles, additional evidence indicates that the regulatory mechanisms involved are distinct.

We identified a novel human homologue of the rat FE65 gene, hFE65L, by screening the cytoplasmic domain of beta-amyloid precursor protein (beta PP) with the "interaction trap." The cytoplasmic domains of the beta PP homologues, APLP1 and APLP2 (amyloid precursor-like proteins), were also tested for interaction with hFE65L. APLP2, but not APLP1, was found to interact with hFE65L. We confirmed these interactions in vivo by successfully coimmunoprecipatating endogenous beta PP and APLP2 from mammalian cells overexpressing a hemagglutinin-tagged fusion of the C-terminal region of hFE65L. We report the existence of a human FE65 gene family and evidence supporting specific interactions between members of the beta PP and FE65 protein families. Sequence analysis of the FE65 human gene family reveals the presence of two phosphotyrosine interaction (PI) domains. Our data show that a single PI domain is sufficient for binding of hFE65L to the cytoplasmic domain of beta PP and APLP2. ...

β‐amyloid (Aβ) is the main constituent of senile plaques seen in Alzheimer's disease. Aβ is derived from the amyloid precursor protein (APP) via proteolytic cleavage by proteases β‐ and β‐secretase. In this study, we examined content and localization of β‐secretase‐cleaved APP (β‐sAPP) in brain tissue sections from the frontal, temporal and occipital lobe. Strong granular β‐sAPP staining was found throughout the gray matter of all three areas, while white matter staining was considerably weaker. β‐sAPP was found to be localized in astrocytes and in axons. We found the β‐sAPP immunostaining to be stronger and more extensive in gray matter in Alzheimer disease (AD) cases than controls. The axonal β‐sAPP staining was patchy and unevenly distributed for the AD cases, indicating impaired axonal transport. β‐sAPP was also found surrounding senile plaques and cerebral blood vessels. The results presented here show altered β‐sAPP staining in the AD brain, suggestive of abnormal processi...

Recent genetic evidence supports a link between microglia and the complement system in Alzheimer’s disease (AD). In this study, we uncovered a novel role for the microglial complement receptor 3 (CR3) in the regulation of soluble &bgr;-amyloid (A&bgr;) clearance independent of phagocytosis. Unexpectedly, ablation of CR3 in human amyloid precursor protein–transgenic mice results in decreased, rather than increased, A&bgr; accumulation. In line with these findings, cultured microglia lacking CR3 are more efficient than wild-type cells at degrading extracellular A&bgr; by secreting enzymatic factors, including tissue plasminogen activator. Furthermore, a small molecule modulator of CR3 reduces soluble A&bgr; levels and A&bgr; half-life in brain interstitial fluid (ISF), as measured by in vivo microdialysis. These results suggest that CR3 limits A&bgr; clearance from the ISF, illustrating a novel role for CR3 and microglia in brain A&bgr; metabolism and defining a potential new therapeu...

BackgroundBiological pathways that significantly contribute to sporadic Alzheimer’s disease are largely unknown and cannot be observed directly. Cognitive symptoms appear only decades after the molecular disease onset, further complicating analyses. As a consequence, molecular research is often restricted to late-stage post-mortem studies of brain tissue. However, the disease process is expected to trigger numerous cellular signaling pathways and modulate the local and systemic environment, and resulting changes in secreted signaling molecules carry information about otherwise inaccessible pathological processes.ResultsTo access this information we probed relative levels of close to 600 secreted signaling proteins from patients’ blood samples using antibody microarrays and mapped disease-specific molecular networks. Using these networks as seeds we then employed independent genome and transcriptome data sets to corroborate potential pathogenic pathways.ConclusionsWe identified Growt...

Cyclin‐dependent kinase 5 (Cdk5) is involved in proper neurodevelopment and brain function and serves as a switch between neuronal survival and death. Overactivation of Cdk5 is associated with many neurodegenerative disorders such as Alzheimer's or Parkinson's diseases. It is believed that in those diseases Cdk5 may be an important link between disease‐initiating factors and cell death effectors. A common hallmark of neurodegenerative disorders is incorrect folding of specific proteins, thus leading to their intra‐ and extracellular accumulation in the nervous system. Abnormal Cdk5 signaling contributes to dysfunction of individual proteins and has a substantial role in either direct or indirect interactions of proteins common to, and critical in, different neurodegenerative diseases. While the roles of Cdk5 in α‐synuclein (ASN) – tau or β‐amyloid peptide (Aβ) – tau interactions are well documented, its contribution to many other pertinent interactions, such as that of ASN w...