Fusheng Yang - Academia.edu (original) (raw)

Papers by Fusheng Yang

Research paper thumbnail of TAMI-42. H3K27M Mutant Gliomas Hijack a Conserved and Critical Metabolic Pathway Used by IDH1 Mutant Gliomas to Maintain Their Preferred Epigenetic State

Neuro-oncology, 2020

H3K27M-midline gliomas are fatal tumors that mainly harbor H3.3K27M mutations resulting in global... more H3K27M-midline gliomas are fatal tumors that mainly harbor H3.3K27M mutations resulting in global H3K27me3 reduction that impacts neuroglial-differentiation. However, the exact mechanisms by which H3.3K27M mutations promote cancer are poorly understood. Metabolic reprogramming is a hallmark of cancer and we hypothesized that H3.3K27M mutations can reprogram metabolism to support uncontrolled growth. We demonstrate that H3.3K27M-mutant cells show elevated levels of critical enzymes related to glycolysis and TCA cycle metabolism including hexokinase-2, isocitrate dehydrogenase (IDH)-1 and glutamate dehydrogenase. H3.3K27M cells also demonstrated enhanced glycolysis, glutamine and TCA-cycle metabolism accompanied by increased alpha-ketoglutarate (α-KG) production. Mutant IDH (mIDH)1/2 converts α-KG to D-2-hydroxyglutarate (D-2HG). D-2HG increases H3K27me3 by inhibiting α-KG’s function to drive H3K27-demethylases. We discovered that H3.3K27M cells use α-KG in an opposing manner to maint...

Research paper thumbnail of Diffuse intrinsic pontine glioma-like tumor with EZHIP expression and molecular features of PFA ependymoma

Acta Neuropathologica Communications, 2020

Research paper thumbnail of Protease Inhibitor Coinfusion with Amyloid β-Protein Results in Enhanced Deposition and Toxicity in Rat Brain

The Journal of Neuroscience, 1998

Amyloid β-protein, Aβ, is normally produced in brain and is cleared by unknown mechanisms. In Alz... more Amyloid β-protein, Aβ, is normally produced in brain and is cleared by unknown mechanisms. In Alzheimer’s disease (AD), Aβ accumulates in plaque-like deposits and is implicated genetically in neurodegeneration. Here we investigate mechanisms for Aβ degradation and Aβ toxicityin vivo, focusing on the effects of Aβ40, which is the peptide that accumulates in apolipoprotein E4-associated AD. Chronic intraventricular infusion of Aβ40 into rat brain resulted in limited deposition and toxicity. Coinfusion of Aβ40 with the cysteine protease inhibitor leupeptin resulted in increased extracellular and intracellular Aβ immunoreactivity. Analysis of gliosis and TUNEL in neuron layers of the frontal and entorhinal cortex suggested that leupeptin exacerbated Aβ40 toxicity. This was supported further by the neuronal staining of cathepsin B in endosomes or lysosomes, colocalizing with intracellular Aβ immunoreactivity in pyknotic cells. Leupeptin plus Aβ40 caused limited but significant neuronal p...

Research paper thumbnail of Dietary DHA supplementation in an APP/PS1 transgenic rat model of AD reduces behavioral and Aβ pathology and modulates Aβ oligomerization

Neurobiology of Disease, 2015

Increased dietary consumption of docosahexaenoic acid (DHA) is associated with decreased risk for... more Increased dietary consumption of docosahexaenoic acid (DHA) is associated with decreased risk for Alzheimer's disease (AD). These effects have been postulated to arise from DHA's pleiotropic effects on AD pathophysiology, including its effects on β-amyloid (Aβ) production, aggregation, and toxicity. While in vitro studies suggest DHA may inhibit and reverse the formation of toxic Aβ oligomers, it remains uncertain whether these mechanisms operate in vivo at the physiological concentrations of DHA attainable through dietary supplementation. We sought to clarify the effects of dietary DHA supplementation on Aβ indices in a transgenic APP/PS1 rat model of AD. Animals maintained on a DHA-supplemented diet exhibited reductions in hippocampal Aβ plaque density and modest improvements on behavioral testing relative to those maintained on a DHAdepleted diet. However, DHA supplementation also increased overall soluble Aβ oligomer levels in the hippocampus. Further quantification of specific conformational populations of Aβ oligomers indicated that DHA supplementation increased fibrillar (i.e. putatively less toxic) Aβ oligomers and decreased prefibrillar (i.e. putatively more toxic) Aβ oligomers. These results provide in vivo

Research paper thumbnail of Antibody to caspase-cleaved actin detects apoptosis in differentiated neuroblastoma and plaque-associated neurons and microglia in Alzheimer's disease

The American journal of pathology, 1998

During apoptosis, activation of a family of cysteine proteases related to interleukin-1beta-conve... more During apoptosis, activation of a family of cysteine proteases related to interleukin-1beta-converting enzyme (ICE)-related proteases or "caspases" results in endoproteolytic cleavage of multiple substrates at specific aspartate residues. We have sought to develop new antibody probes for the neoepitopes in protein fragments produced by ICE-related proteolytic cleavage as specific markers of events tightly linked to apoptotic mechanisms. Here, we demonstrate that an antibody probe specific for the C terminus of a 32-kd actin fragment produced by ICE-like activity specifically labels apoptotic but not necrotic, differentiated human neuroblastoma cells in culture. Unlike probes for nonspecific DNA strand breaks confined to the nucleus or cell body, this method allows the detection of cytoskeletal fragments in cell processes as well as the perikaryon long before DNA fragmentation and cell death and therefore serves as a novel marker of apoptosis-related events in distal parts ...

Research paper thumbnail of Microglial response to amyloid plaques in APPsw transgenic mice

The American journal of pathology, 1998

Microglial activation is central to the inflammatory response in Alzheimer's Disease (AD). A ... more Microglial activation is central to the inflammatory response in Alzheimer's Disease (AD). A recently described mouse line, Tg(HuAPP695.K670N/M671L)2576, expressing human amyloid precursor protein with a familial AD gene mutation, age-related amyloid deposits, and memory deficits, was found to develop a significant microglial response using Griffonia simplicifolia lectin or phosphotyrosine probe to identify microglia Both Griffonia simplicifolia lectin and phosphotyrosine staining showed increased numbers of intensely labeled, often enlarged microglia clustered in and around plaques, consistent with microglial activation related to beta-amyloid formation. Using quantitative image analysis of coronal phosphotyrosine-immunostained sections, transgene-positive 10- to 16-month-old, hemizygous, hybrid Tg2576 (APPsw) animals showed significantly increased microglial density and size in plaque-forming areas of hippocampus and frontal, entorhinal, and occipital cortex. Quantitative anal...

Research paper thumbnail of Amyloid β-protein length and cerebral amyloid angiopathy-related haemorrhage

NeuroReport, 2000

The relationship between amyloid â-protein (Aâ) length and the apolipoprotein E (APOE) å2 allele,... more The relationship between amyloid â-protein (Aâ) length and the apolipoprotein E (APOE) å2 allele, which is over-represented in cerebral amyloid angiopathy-related haemorrhage (CAAH), has not previously been examined. Of 57 CAA patients studied, 37 had CAAH. All patients, particularly those with CAAH had more blood vessels immunoreactive for Aâ40 than Aâ42 in both the leptomeninges and cerebral cortex. CAAH patients had more Aâ40-immunoreactive blood vessels in the leptomeninges (p , 0.001) and cortex (p 0.027) than had non-haemorrhage patients. Cortical blood vessels, the usual source of haemorrhage in CAAH, were more frequently Aâ42 immunoreactive in APOE å2 carriers than in non-å2 carriers (p 0.022). The APOE å2 allele may predispose to CAAH by increasing the seeding of cortical blood vessels by Aâ42. NeuroReport 11:937±940 &

Research paper thumbnail of Carboxy terminal of β-amyloid deposits in aged human, canine, and polar bear brains

Neurobiology of Aging, 1996

249-257, 1996.-Immunocytochemistry, using antibodies specific for different carboxy termini of [3... more 249-257, 1996.-Immunocytochemistry, using antibodies specific for different carboxy termini of [3-amyloid, AI340 and AI342(43), was used to compare [3-amyloid deposits in aged animal models to nondemented and demented Alzheimer's disease human cases. Aged beagle dogs exhibit diffuse plaques in the absence of neurofibrillary pathology and the aged polar bear brains contain diffuse plaques and PHF-l-positiw~ neurofibrillary tangles. The brains of nondemented human subjects displayed abundant diffuse plaques, whereas the AD cases had both diffuse and mature (cored) neuritic plaques. Diffuse plaques were positively immunostained with an antibody against A[342(43) in all examined species, whereas AI340 immunopositive mature plaques were observed only in the human brain. Anti-Al~40 strongly immunolabeled cerebrovascular [3-amyloid deposits in each of the species examined, although some deposits in the polar bear brain were preferentially labeled with anti-A[342(43). [3-Amyloid deposition was evident in the outer molecular layer of the dentate gyrus in the aged dog, polar bear, and human. Within this layer, A1342 was present as diffuse deposits, although these deposits were morphologically distinct in each of the examined animal models. In dogs, A[342 was cloud-like in nature; the polar bear demonstrated a more aggregated type of deposition, and the nondemented human displayed well-defined deposits. Alzheimer's disease cases were most frequently marked by neuritic plaques in this region. Taken together, the data indicate that 13-amyloid deposition in aged mammals is similar to the earliest stages observed in human brain. In each species, AI342(43) is the initially deposited isoform in diffuse plaques.

Research paper thumbnail of Effect of chloroquine and leupeptin on intracellular accumulation of amyloid-beta (Aβ) 1-42 peptide in a murine N9 microglial cell line

FEBS Letters, 1998

Murine N9 microglia accumulated AL L from media containing 0.67 W WM AL L within 6 h. In N9 and i... more Murine N9 microglia accumulated AL L from media containing 0.67 W WM AL L within 6 h. In N9 and in primary rat microglia, chloroquine, which disrupts lysosomal pH, increased AL L-induced accumulation of AL L, particularly AL L1^42. Leupeptin similarly enhanced AL L accumulation. The scavenger receptor antagonist fucoidan did not affect acute chloroquine-dependent AL L1^42 accumulation, demonstrating uptake of non-aggregated AL L. After prolonged incubations, chloroquine enhanced AL L multimer (8^12 kDa) accumulation, an effect inhibited by fucoidan. Disruptions of the lysosomal system enhance AL L and its multimer formation. Despite negligible effects of fucoidan on initial AL L uptake, chronic exposure inhibits multimer accumulation, demonstrating a role for scavenger receptor in multimer accumulation.

Research paper thumbnail of Multiple-label immunocytochemistry for the evaluation of nature of cell death in experimental models of neurodegeneration

Brain Research Protocols, 2001

A prominent feature of neurodegenerative diseases is a loss of specific neuronal populations. The... more A prominent feature of neurodegenerative diseases is a loss of specific neuronal populations. The pathophysiological mechanisms responsible are, however, poorly understood. Primary cultures of rodent embryonic neurons represent a useful experimental system for investigation of molecular pathways of neurodegeneration and mechanisms of cell death. Here, we report a technique utilizing triple-label immunocytochemistry with confocal immunofluorescence detection designed to simultaneously assess multiple parameters of cell injury in individual hippocampal neurons in primary culture. This method combines detection of DNA damage (TUNEL or Klenow assay) with double-label immunocytochemistry for the activated form of caspase-3 or, alternatively, caspase-cleaved actin (fractin), and microtubuleassociated protein-2 (MAP-2) or b-tubulin. The combined evaluation of the form of nuclear damage (karyorrhexis, pyknosis), the presence or absence of activated caspase-3, and the extent of the damage to cell cytoskeleton, allows for precise assessment of the extent of injury and the mode of cell death (apoptosis, oncosis) for individual neurons.

Research paper thumbnail of Co-Localization of Amyloid Beta and Tau Pathology in Alzheimer's Disease Synaptosomes

The American Journal of Pathology, 2008

The amyloid cascade hypothesis proposes that amyloid ␤ (A␤) pathology precedes and induces tau pa... more The amyloid cascade hypothesis proposes that amyloid ␤ (A␤) pathology precedes and induces tau pathology, but the neuropathological connection between these two lesions has not been demonstrated. We examined the regional distribution and co-localization of A␤ and phosphorylated tau (p-tau) in synaptic terminals of Alzheimer's disease brains. To quantitatively examine large populations of individual synaptic terminals, flow cytometry was used to analyze synaptosomes prepared from cryopreserved Alzheimer's disease tissue. An average 68.4% of synaptic terminals in the Alzheimer's disease cohort (n ‫؍‬ 11) were positive for A␤, and 32.3% were positive for p-tau; A␤ and p-tau fluorescence was lowest in cerebellum. In contrast to synaptic p-tau, which was highest in the entorhinal cortex and hippocampus (P ‫؍‬ 0.004), synaptic A␤ fluorescence was significantly lower in the entorhinal cortex and hippocampus relative to neocortical regions (P ‫؍‬ 0.0003). Synaptic A␤ and p-tau fluorescence was significantly correlated (r ‫؍‬ 0.683, P < 0.004), and dual-labeling experiments demonstrated that 24.1% of A␤-positive terminals were also positive for p-tau, with the highest fraction of dual labeling (39.3%) in the earliest affected region, the entorhinal cortex. Western blotting experiments show a significant correlation between synaptic A␤ levels measured by flow cytometry and oligomeric A␤ species (P < 0.0001). These results showing overlapping A␤ and tau pathology are consistent with a model in which both synaptic loss and dysfunction are linked to a synaptic amyloid cascade within the synaptic compartment.

Research paper thumbnail of CAA in Transgenic Mouse Models of Alzheimer’s Disease

Cerebral Amyloid Angiopathy in Alzheimer’s Disease and Related Disorders, 2000

The development of mouse lines with high level expression of mutant P-amyloid precursor protein (... more The development of mouse lines with high level expression of mutant P-amyloid precursor protein (APP) trangenes has afforded researchers convenient animal models with CNS Pamyloidosis. Two well-characterized lines bearing neuronally expressed human APP with "Swedish" double mutations with dramatically increased production of Ap 1_40 and AP 1.42, develop significant neuritic plaque and vascular amyloidosis. Other transgenics with the " London" APP mutant transgene, which results in an increased percentage of APP processed to AP 1. 42 but not AP 1.40, show very high levels of primarily plaque amyloid suggesting that the site of deposition depends on the relative levels of the different AP species. The roles of transforming growth factor P 1 and apolipoprotein E in both CAA and plaque amyloid deposition are also being addressed in transgenic mouse models. From a review of the literature on amyloidosis in transgenic mice, we develop several hypotheses about how AP accumulates in CAA and discuss possible applications of APP transgenics to research on the prevention and treatment of CAA.

Research paper thumbnail of Ibuprofen Suppresses Plaque Pathology and Inflammation in a Mouse Model for Alzheimer's Disease

The Journal of Neuroscience, 2000

The brain in Alzheimer's disease (AD) shows a chronic inflammatory response characterized by acti... more The brain in Alzheimer's disease (AD) shows a chronic inflammatory response characterized by activated glial cells and increased expression of cytokines and complement factors surrounding amyloid deposits. Several epidemiological studies have demonstrated a reduced risk for AD in patients using nonsteroidal anti-inflammatory drugs (NSAIDs), prompting further inquiries about how NSAIDs might influence the development of AD pathology and inflammation in the CNS. We tested the impact of chronic orally administered ibuprofen, the most commonly used NSAID, in a transgenic model of AD displaying widespread microglial activation, age-related amyloid deposits, and dystrophic neurites. These mice were created by overexpressing a variant of the amyloid precursor protein found in familial AD. Transgenepositive (Tgϩ) and negative (TgϪ) mice began receiving chow containing 375 ppm ibuprofen at 10 months of age, when amyloid plaques first appear, and were fed continuously for 6 months. This treatment produced significant reductions in final interleukin-1␤ and glial fibrillary acidic protein levels, as well as a significant diminution in the ultimate number and total area of ␤-amyloid deposits. Reductions in amyloid deposition were supported by ELISA measurements showing significantly decreased SDS-insoluble A␤. Ibuprofen also decreased the numbers of ubiquitin-labeled dystrophic neurites and the percentage area per plaque of antiphosphotyrosine-labeled microglia. Thus, the anti-inflammatory drug ibuprofen, which has been associated with reduced AD risk in human epidemiological studies, can significantly delay some forms of AD pathology, including amyloid deposition, when administered early in the disease course of a transgenic mouse model of AD.

Research paper thumbnail of The Curry Spice Curcumin Reduces Oxidative Damage and Amyloid Pathology in an Alzheimer Transgenic Mouse

The Journal of Neuroscience, 2001

Inflammation in Alzheimer's disease (AD) patients is characterized by increased cytokines and act... more Inflammation in Alzheimer's disease (AD) patients is characterized by increased cytokines and activated microglia. Epidemiological studies suggest reduced AD risk associates with longterm use of nonsteroidal anti-inflammatory drugs (NSAIDs). Whereas chronic ibuprofen suppressed inflammation and plaque-related pathology in an Alzheimer transgenic APPSw mouse model (Tg2576), excessive use of NSAIDs targeting cyclooxygenase I can cause gastrointestinal, liver, and renal toxicity. One alternative NSAID is curcumin, derived from the curry spice turmeric. Curcumin has an extensive history as a food additive and herbal medicine in India and is also a potent polyphenolic antioxidant. To evaluate whether it could affect Alzheimer-like pathology in the APPSw mice, we tested a low (160 ppm) and a high dose of dietary curcumin (5000 ppm) on inflammation, oxidative damage, and plaque pathology. Low and high doses of curcumin significantly lowered oxidized proteins and interleukin-1␤, a proinflammatory cytokine elevated in the brains of these mice. With low-dose but not high-dose curcumin treatment, the astrocytic marker GFAP was reduced, and insoluble ␤-amyloid (A␤), soluble A␤, and plaque burden were significantly decreased by 43-50%. However, levels of amyloid precursor (APP) in the membrane fraction were not reduced. Microgliosis was also suppressed in neuronal layers but not adjacent to plaques. In view of its efficacy and apparent low toxicity, this Indian spice component shows promise for the prevention of Alzheimer's disease.

Research paper thumbnail of Use of Copper and Insulin-Resistance to Accelerate Cognitive Deficits and Synaptic Protein Loss in a Rat Aβ-Infusion Alzheimer's Disease Model

Journal of Alzheimer's Disease, 2008

The rat amyloid-β (Aβ) intracerebroventricular infusion can model aspects of Alzheimer's disease ... more The rat amyloid-β (Aβ) intracerebroventricular infusion can model aspects of Alzheimer's disease (AD) and has predicted efficacy of therapies such as ibuprofen and curcumin in transgenic mouse models. High density lipoprotein (HDL), a normal plasma carrier of Aβ, is used to attenuate Aβ aggregation within the pump, causing Aβ-dependent toxicity and cognitive deficits within 3 months. Our goal was to identify factors that might accelerate onset of Aβ-dependent deficits to improve efficiency and cost-effectiveness of model. We focused on: 1) optimizing HDL-Aβ preparation for maximal toxicity; 2) evaluating the role of copper, a factor typically in water that can impact oligomer stability; and 3) determining impact of insulin resistance (type II diabetes), a risk factor for AD. In vitro studies were performed to determine doses of copper and methods of Aβ-HDL preparation that maximized toxicity. These preparations when infused resulted in earlier onset of cognitive deficits within 6 weeks post-infusion. Induction of insulin resistance did not exacerbate Aβ-dependent cognitive deficits, but did exacerbate synaptic protein loss. In summary, the newly described in vivo infusion model may be useful cost-effective method for screening for new therapeutic drugs for AD.

Research paper thumbnail of PAK in Alzheimer disease, Huntington disease and X-linked mental retardation

Research paper thumbnail of Rodent models of Alzheimer's disease: Rat aβ infusion approaches to amyloid deposits

Neurobiology of Aging, 1996

Research paper thumbnail of Enrichment of presynaptic and postsynaptic markers by size-based gating analysis of synaptosome preparations from rat and human cortex

Cytometry, 2004

Background: Synapse regions in the brain are difficult to isolate and study; resealed nerve termi... more Background: Synapse regions in the brain are difficult to isolate and study; resealed nerve terminals (synaptosomes) are a widely used in vitro system for the study of neurotransmission, but nonsynaptosomal elements in the homogenate complicate data interpretation. With the goal of quantitative analysis of pathways leading to synapse loss in neurodegenerative disease, we have developed a method that allows focus on the intact synaptosomes within a crude synaptosomal preparation by gating the largest particles based on forward angle light scatter (FSC). Methods: Crude synaptosomal fractions (P-2) were prepared and labeled with a viability dye (calcein AM), a presynaptic marker (SNAP-25), and a postsynaptic marker (PSD-95). Forward scatter gates based on size standards were drawn to identify the large population (1.4-4.5 m), and the enrichment of each marker was quantified in preparations from fresh rat homogenates and from cryopreserved human cortex. Results: Gating on forward scatter resulted in an increase that was highly significant (P Ͻ 0.001) for all three markers examined. The calcein-AM-positive fraction in the large synaptosomes was 98% Ϯ 0.8, and 75% Ϯ 9.8 for rat and human, respectively. Of large particles, 90% Ϯ 2.7 in rat and 82% Ϯ 2.6 in human were positive for SNAP-25, indicating a relatively pure population of intact synaptosomes. A total of 76% Ϯ 2.9 of the large particles were positive for PSD-95 in rat. This compared to 36% Ϯ 3.0 in human tissue, and indicates that both presynaptic and postsynaptic elements may be analyzed with this methodology. Conclusions: Most nonsynaptosomal elements can be excluded and the intact subpopulation of interest within the P-2 can be identified based on size. Size-based gating analysis provides a simple and cost-effective method to monitor fluorescence changes in synapse regions.

Research paper thumbnail of Loss of MAP Function Leads to Hippocampal Synapse Loss and Deficits in the Morris Water Maze with Aging

Journal of Neuroscience, 2014

Hyperphosphorylation and accumulation of tau aggregates are prominent features in tauopathies, in... more Hyperphosphorylation and accumulation of tau aggregates are prominent features in tauopathies, including Alzheimer's disease, but the impact of loss of tau function on synaptic and cognitive deficits remains poorly understood. We report that old (19-20 months; OKO) but not middle-aged (8-9 months; MKO) tau knockout mice develop Morris Water Maze (MWM) deficits and loss of hippocampal acetylated ␣-tubulin and excitatory synaptic proteins. Mild motor deficits and reduction in tyrosine hydroxylase (TH) in the substantia nigra were present by middle age, but did not affect MWM performance, whereas OKO mice showed MWM deficits paralleling hippocampal deficits. Deletion of tau, a microtubule-associated protein (MAP), resulted in increased levels of MAP1A, MAP1B, and MAP2 in MKO, followed by loss of MAP2 and MAP1B in OKO. Hippocampal synaptic deficits in OKO mice were partially corrected with dietary supplementation with docosahexaenoic acid (DHA) and both MWM and synaptic deficits were fully corrected by combining DHA with ␣-lipoic acid (ALA), which also prevented TH loss. DHA or DHA/ALA restored phosphorylated and total GSK3␤ and attenuated hyperactivation of the tau C-Jun N-terminal kinases (JNKs) while increasing MAP1B, dephosphorylated (active) MAP2, and acetylated ␣-tubulin, suggesting improved microtubule stability and maintenance of active compensatory MAPs. Our results implicate the loss of MAP function in ageassociated hippocampal deficits and identify a safe dietary intervention, rescuing both MAP function and TH in OKO mice. Therefore, in addition to microtubule-stabilizing therapeutic drugs, preserving or restoring compensatory MAP function may be a useful new prevention strategy.

Research paper thumbnail of A Diet Enriched with the Omega-3 Fatty Acid Docosahexaenoic Acid Reduces Amyloid Burden in an Aged Alzheimer Mouse Model

Journal of Neuroscience, 2005

Epidemiological studies suggest that increased intake of the omega-3 (n-3) polyunsaturated fatty ... more Epidemiological studies suggest that increased intake of the omega-3 (n-3) polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) is associated with reduced risk of Alzheimer's disease (AD). DHA levels are lower in serum and brains of AD patients, which could result from low dietary intake and/or PUFA oxidation. Because effects of DHA on Alzheimer pathogenesis, particularly on amyloidosis, are unknown, we used the APPsw (Tg2576) transgenic mouse model to evaluate the impact of dietary DHA on amyloid precursor protein (APP) processing and amyloid burden. Aged animals (17-19 months old) were placed in one of three groups until 22.5 months of age: control (0.09% DHA), low-DHA (0%), or high-DHA (0.6%) chow. ␤-Amyloid (A␤) ELISA of the detergent-insoluble extract of cortical homogenates showed that DHA-enriched diets significantly reduced total A␤ by Ͼ70% when compared with low-DHA or control chow diets. Dietary DHA also decreased A␤42 levels below those seen with control chow. Image analysis of brain sections with an antibody against A␤ (amino acids 1-13) revealed that overall plaque burden was significantly reduced by 40.3%, with the largest reductions (40-50%) in the hippocampus and parietal cortex. DHA modulated APP processing by decreasing both ␣and ␤-APP C-terminal fragment products and full-length APP. BACE1 (␤-secretase activity of the ␤-site APP-cleaving enzyme), ApoE (apolipoprotein E), and transthyretin gene expression were unchanged with the high-DHA diet. Together, these results suggest that dietary DHA could be protective against ␤-amyloid production, accumulation, and potential downstream toxicity.

Research paper thumbnail of TAMI-42. H3K27M Mutant Gliomas Hijack a Conserved and Critical Metabolic Pathway Used by IDH1 Mutant Gliomas to Maintain Their Preferred Epigenetic State

Neuro-oncology, 2020

H3K27M-midline gliomas are fatal tumors that mainly harbor H3.3K27M mutations resulting in global... more H3K27M-midline gliomas are fatal tumors that mainly harbor H3.3K27M mutations resulting in global H3K27me3 reduction that impacts neuroglial-differentiation. However, the exact mechanisms by which H3.3K27M mutations promote cancer are poorly understood. Metabolic reprogramming is a hallmark of cancer and we hypothesized that H3.3K27M mutations can reprogram metabolism to support uncontrolled growth. We demonstrate that H3.3K27M-mutant cells show elevated levels of critical enzymes related to glycolysis and TCA cycle metabolism including hexokinase-2, isocitrate dehydrogenase (IDH)-1 and glutamate dehydrogenase. H3.3K27M cells also demonstrated enhanced glycolysis, glutamine and TCA-cycle metabolism accompanied by increased alpha-ketoglutarate (α-KG) production. Mutant IDH (mIDH)1/2 converts α-KG to D-2-hydroxyglutarate (D-2HG). D-2HG increases H3K27me3 by inhibiting α-KG’s function to drive H3K27-demethylases. We discovered that H3.3K27M cells use α-KG in an opposing manner to maint...

Research paper thumbnail of Diffuse intrinsic pontine glioma-like tumor with EZHIP expression and molecular features of PFA ependymoma

Acta Neuropathologica Communications, 2020

Research paper thumbnail of Protease Inhibitor Coinfusion with Amyloid β-Protein Results in Enhanced Deposition and Toxicity in Rat Brain

The Journal of Neuroscience, 1998

Amyloid β-protein, Aβ, is normally produced in brain and is cleared by unknown mechanisms. In Alz... more Amyloid β-protein, Aβ, is normally produced in brain and is cleared by unknown mechanisms. In Alzheimer’s disease (AD), Aβ accumulates in plaque-like deposits and is implicated genetically in neurodegeneration. Here we investigate mechanisms for Aβ degradation and Aβ toxicityin vivo, focusing on the effects of Aβ40, which is the peptide that accumulates in apolipoprotein E4-associated AD. Chronic intraventricular infusion of Aβ40 into rat brain resulted in limited deposition and toxicity. Coinfusion of Aβ40 with the cysteine protease inhibitor leupeptin resulted in increased extracellular and intracellular Aβ immunoreactivity. Analysis of gliosis and TUNEL in neuron layers of the frontal and entorhinal cortex suggested that leupeptin exacerbated Aβ40 toxicity. This was supported further by the neuronal staining of cathepsin B in endosomes or lysosomes, colocalizing with intracellular Aβ immunoreactivity in pyknotic cells. Leupeptin plus Aβ40 caused limited but significant neuronal p...

Research paper thumbnail of Dietary DHA supplementation in an APP/PS1 transgenic rat model of AD reduces behavioral and Aβ pathology and modulates Aβ oligomerization

Neurobiology of Disease, 2015

Increased dietary consumption of docosahexaenoic acid (DHA) is associated with decreased risk for... more Increased dietary consumption of docosahexaenoic acid (DHA) is associated with decreased risk for Alzheimer's disease (AD). These effects have been postulated to arise from DHA's pleiotropic effects on AD pathophysiology, including its effects on β-amyloid (Aβ) production, aggregation, and toxicity. While in vitro studies suggest DHA may inhibit and reverse the formation of toxic Aβ oligomers, it remains uncertain whether these mechanisms operate in vivo at the physiological concentrations of DHA attainable through dietary supplementation. We sought to clarify the effects of dietary DHA supplementation on Aβ indices in a transgenic APP/PS1 rat model of AD. Animals maintained on a DHA-supplemented diet exhibited reductions in hippocampal Aβ plaque density and modest improvements on behavioral testing relative to those maintained on a DHAdepleted diet. However, DHA supplementation also increased overall soluble Aβ oligomer levels in the hippocampus. Further quantification of specific conformational populations of Aβ oligomers indicated that DHA supplementation increased fibrillar (i.e. putatively less toxic) Aβ oligomers and decreased prefibrillar (i.e. putatively more toxic) Aβ oligomers. These results provide in vivo

Research paper thumbnail of Antibody to caspase-cleaved actin detects apoptosis in differentiated neuroblastoma and plaque-associated neurons and microglia in Alzheimer's disease

The American journal of pathology, 1998

During apoptosis, activation of a family of cysteine proteases related to interleukin-1beta-conve... more During apoptosis, activation of a family of cysteine proteases related to interleukin-1beta-converting enzyme (ICE)-related proteases or "caspases" results in endoproteolytic cleavage of multiple substrates at specific aspartate residues. We have sought to develop new antibody probes for the neoepitopes in protein fragments produced by ICE-related proteolytic cleavage as specific markers of events tightly linked to apoptotic mechanisms. Here, we demonstrate that an antibody probe specific for the C terminus of a 32-kd actin fragment produced by ICE-like activity specifically labels apoptotic but not necrotic, differentiated human neuroblastoma cells in culture. Unlike probes for nonspecific DNA strand breaks confined to the nucleus or cell body, this method allows the detection of cytoskeletal fragments in cell processes as well as the perikaryon long before DNA fragmentation and cell death and therefore serves as a novel marker of apoptosis-related events in distal parts ...

Research paper thumbnail of Microglial response to amyloid plaques in APPsw transgenic mice

The American journal of pathology, 1998

Microglial activation is central to the inflammatory response in Alzheimer's Disease (AD). A ... more Microglial activation is central to the inflammatory response in Alzheimer's Disease (AD). A recently described mouse line, Tg(HuAPP695.K670N/M671L)2576, expressing human amyloid precursor protein with a familial AD gene mutation, age-related amyloid deposits, and memory deficits, was found to develop a significant microglial response using Griffonia simplicifolia lectin or phosphotyrosine probe to identify microglia Both Griffonia simplicifolia lectin and phosphotyrosine staining showed increased numbers of intensely labeled, often enlarged microglia clustered in and around plaques, consistent with microglial activation related to beta-amyloid formation. Using quantitative image analysis of coronal phosphotyrosine-immunostained sections, transgene-positive 10- to 16-month-old, hemizygous, hybrid Tg2576 (APPsw) animals showed significantly increased microglial density and size in plaque-forming areas of hippocampus and frontal, entorhinal, and occipital cortex. Quantitative anal...

Research paper thumbnail of Amyloid β-protein length and cerebral amyloid angiopathy-related haemorrhage

NeuroReport, 2000

The relationship between amyloid â-protein (Aâ) length and the apolipoprotein E (APOE) å2 allele,... more The relationship between amyloid â-protein (Aâ) length and the apolipoprotein E (APOE) å2 allele, which is over-represented in cerebral amyloid angiopathy-related haemorrhage (CAAH), has not previously been examined. Of 57 CAA patients studied, 37 had CAAH. All patients, particularly those with CAAH had more blood vessels immunoreactive for Aâ40 than Aâ42 in both the leptomeninges and cerebral cortex. CAAH patients had more Aâ40-immunoreactive blood vessels in the leptomeninges (p , 0.001) and cortex (p 0.027) than had non-haemorrhage patients. Cortical blood vessels, the usual source of haemorrhage in CAAH, were more frequently Aâ42 immunoreactive in APOE å2 carriers than in non-å2 carriers (p 0.022). The APOE å2 allele may predispose to CAAH by increasing the seeding of cortical blood vessels by Aâ42. NeuroReport 11:937±940 &

Research paper thumbnail of Carboxy terminal of β-amyloid deposits in aged human, canine, and polar bear brains

Neurobiology of Aging, 1996

249-257, 1996.-Immunocytochemistry, using antibodies specific for different carboxy termini of [3... more 249-257, 1996.-Immunocytochemistry, using antibodies specific for different carboxy termini of [3-amyloid, AI340 and AI342(43), was used to compare [3-amyloid deposits in aged animal models to nondemented and demented Alzheimer's disease human cases. Aged beagle dogs exhibit diffuse plaques in the absence of neurofibrillary pathology and the aged polar bear brains contain diffuse plaques and PHF-l-positiw~ neurofibrillary tangles. The brains of nondemented human subjects displayed abundant diffuse plaques, whereas the AD cases had both diffuse and mature (cored) neuritic plaques. Diffuse plaques were positively immunostained with an antibody against A[342(43) in all examined species, whereas AI340 immunopositive mature plaques were observed only in the human brain. Anti-Al~40 strongly immunolabeled cerebrovascular [3-amyloid deposits in each of the species examined, although some deposits in the polar bear brain were preferentially labeled with anti-A[342(43). [3-Amyloid deposition was evident in the outer molecular layer of the dentate gyrus in the aged dog, polar bear, and human. Within this layer, A1342 was present as diffuse deposits, although these deposits were morphologically distinct in each of the examined animal models. In dogs, A[342 was cloud-like in nature; the polar bear demonstrated a more aggregated type of deposition, and the nondemented human displayed well-defined deposits. Alzheimer's disease cases were most frequently marked by neuritic plaques in this region. Taken together, the data indicate that 13-amyloid deposition in aged mammals is similar to the earliest stages observed in human brain. In each species, AI342(43) is the initially deposited isoform in diffuse plaques.

Research paper thumbnail of Effect of chloroquine and leupeptin on intracellular accumulation of amyloid-beta (Aβ) 1-42 peptide in a murine N9 microglial cell line

FEBS Letters, 1998

Murine N9 microglia accumulated AL L from media containing 0.67 W WM AL L within 6 h. In N9 and i... more Murine N9 microglia accumulated AL L from media containing 0.67 W WM AL L within 6 h. In N9 and in primary rat microglia, chloroquine, which disrupts lysosomal pH, increased AL L-induced accumulation of AL L, particularly AL L1^42. Leupeptin similarly enhanced AL L accumulation. The scavenger receptor antagonist fucoidan did not affect acute chloroquine-dependent AL L1^42 accumulation, demonstrating uptake of non-aggregated AL L. After prolonged incubations, chloroquine enhanced AL L multimer (8^12 kDa) accumulation, an effect inhibited by fucoidan. Disruptions of the lysosomal system enhance AL L and its multimer formation. Despite negligible effects of fucoidan on initial AL L uptake, chronic exposure inhibits multimer accumulation, demonstrating a role for scavenger receptor in multimer accumulation.

Research paper thumbnail of Multiple-label immunocytochemistry for the evaluation of nature of cell death in experimental models of neurodegeneration

Brain Research Protocols, 2001

A prominent feature of neurodegenerative diseases is a loss of specific neuronal populations. The... more A prominent feature of neurodegenerative diseases is a loss of specific neuronal populations. The pathophysiological mechanisms responsible are, however, poorly understood. Primary cultures of rodent embryonic neurons represent a useful experimental system for investigation of molecular pathways of neurodegeneration and mechanisms of cell death. Here, we report a technique utilizing triple-label immunocytochemistry with confocal immunofluorescence detection designed to simultaneously assess multiple parameters of cell injury in individual hippocampal neurons in primary culture. This method combines detection of DNA damage (TUNEL or Klenow assay) with double-label immunocytochemistry for the activated form of caspase-3 or, alternatively, caspase-cleaved actin (fractin), and microtubuleassociated protein-2 (MAP-2) or b-tubulin. The combined evaluation of the form of nuclear damage (karyorrhexis, pyknosis), the presence or absence of activated caspase-3, and the extent of the damage to cell cytoskeleton, allows for precise assessment of the extent of injury and the mode of cell death (apoptosis, oncosis) for individual neurons.

Research paper thumbnail of Co-Localization of Amyloid Beta and Tau Pathology in Alzheimer's Disease Synaptosomes

The American Journal of Pathology, 2008

The amyloid cascade hypothesis proposes that amyloid ␤ (A␤) pathology precedes and induces tau pa... more The amyloid cascade hypothesis proposes that amyloid ␤ (A␤) pathology precedes and induces tau pathology, but the neuropathological connection between these two lesions has not been demonstrated. We examined the regional distribution and co-localization of A␤ and phosphorylated tau (p-tau) in synaptic terminals of Alzheimer's disease brains. To quantitatively examine large populations of individual synaptic terminals, flow cytometry was used to analyze synaptosomes prepared from cryopreserved Alzheimer's disease tissue. An average 68.4% of synaptic terminals in the Alzheimer's disease cohort (n ‫؍‬ 11) were positive for A␤, and 32.3% were positive for p-tau; A␤ and p-tau fluorescence was lowest in cerebellum. In contrast to synaptic p-tau, which was highest in the entorhinal cortex and hippocampus (P ‫؍‬ 0.004), synaptic A␤ fluorescence was significantly lower in the entorhinal cortex and hippocampus relative to neocortical regions (P ‫؍‬ 0.0003). Synaptic A␤ and p-tau fluorescence was significantly correlated (r ‫؍‬ 0.683, P < 0.004), and dual-labeling experiments demonstrated that 24.1% of A␤-positive terminals were also positive for p-tau, with the highest fraction of dual labeling (39.3%) in the earliest affected region, the entorhinal cortex. Western blotting experiments show a significant correlation between synaptic A␤ levels measured by flow cytometry and oligomeric A␤ species (P < 0.0001). These results showing overlapping A␤ and tau pathology are consistent with a model in which both synaptic loss and dysfunction are linked to a synaptic amyloid cascade within the synaptic compartment.

Research paper thumbnail of CAA in Transgenic Mouse Models of Alzheimer’s Disease

Cerebral Amyloid Angiopathy in Alzheimer’s Disease and Related Disorders, 2000

The development of mouse lines with high level expression of mutant P-amyloid precursor protein (... more The development of mouse lines with high level expression of mutant P-amyloid precursor protein (APP) trangenes has afforded researchers convenient animal models with CNS Pamyloidosis. Two well-characterized lines bearing neuronally expressed human APP with "Swedish" double mutations with dramatically increased production of Ap 1_40 and AP 1.42, develop significant neuritic plaque and vascular amyloidosis. Other transgenics with the " London" APP mutant transgene, which results in an increased percentage of APP processed to AP 1. 42 but not AP 1.40, show very high levels of primarily plaque amyloid suggesting that the site of deposition depends on the relative levels of the different AP species. The roles of transforming growth factor P 1 and apolipoprotein E in both CAA and plaque amyloid deposition are also being addressed in transgenic mouse models. From a review of the literature on amyloidosis in transgenic mice, we develop several hypotheses about how AP accumulates in CAA and discuss possible applications of APP transgenics to research on the prevention and treatment of CAA.

Research paper thumbnail of Ibuprofen Suppresses Plaque Pathology and Inflammation in a Mouse Model for Alzheimer's Disease

The Journal of Neuroscience, 2000

The brain in Alzheimer's disease (AD) shows a chronic inflammatory response characterized by acti... more The brain in Alzheimer's disease (AD) shows a chronic inflammatory response characterized by activated glial cells and increased expression of cytokines and complement factors surrounding amyloid deposits. Several epidemiological studies have demonstrated a reduced risk for AD in patients using nonsteroidal anti-inflammatory drugs (NSAIDs), prompting further inquiries about how NSAIDs might influence the development of AD pathology and inflammation in the CNS. We tested the impact of chronic orally administered ibuprofen, the most commonly used NSAID, in a transgenic model of AD displaying widespread microglial activation, age-related amyloid deposits, and dystrophic neurites. These mice were created by overexpressing a variant of the amyloid precursor protein found in familial AD. Transgenepositive (Tgϩ) and negative (TgϪ) mice began receiving chow containing 375 ppm ibuprofen at 10 months of age, when amyloid plaques first appear, and were fed continuously for 6 months. This treatment produced significant reductions in final interleukin-1␤ and glial fibrillary acidic protein levels, as well as a significant diminution in the ultimate number and total area of ␤-amyloid deposits. Reductions in amyloid deposition were supported by ELISA measurements showing significantly decreased SDS-insoluble A␤. Ibuprofen also decreased the numbers of ubiquitin-labeled dystrophic neurites and the percentage area per plaque of antiphosphotyrosine-labeled microglia. Thus, the anti-inflammatory drug ibuprofen, which has been associated with reduced AD risk in human epidemiological studies, can significantly delay some forms of AD pathology, including amyloid deposition, when administered early in the disease course of a transgenic mouse model of AD.

Research paper thumbnail of The Curry Spice Curcumin Reduces Oxidative Damage and Amyloid Pathology in an Alzheimer Transgenic Mouse

The Journal of Neuroscience, 2001

Inflammation in Alzheimer's disease (AD) patients is characterized by increased cytokines and act... more Inflammation in Alzheimer's disease (AD) patients is characterized by increased cytokines and activated microglia. Epidemiological studies suggest reduced AD risk associates with longterm use of nonsteroidal anti-inflammatory drugs (NSAIDs). Whereas chronic ibuprofen suppressed inflammation and plaque-related pathology in an Alzheimer transgenic APPSw mouse model (Tg2576), excessive use of NSAIDs targeting cyclooxygenase I can cause gastrointestinal, liver, and renal toxicity. One alternative NSAID is curcumin, derived from the curry spice turmeric. Curcumin has an extensive history as a food additive and herbal medicine in India and is also a potent polyphenolic antioxidant. To evaluate whether it could affect Alzheimer-like pathology in the APPSw mice, we tested a low (160 ppm) and a high dose of dietary curcumin (5000 ppm) on inflammation, oxidative damage, and plaque pathology. Low and high doses of curcumin significantly lowered oxidized proteins and interleukin-1␤, a proinflammatory cytokine elevated in the brains of these mice. With low-dose but not high-dose curcumin treatment, the astrocytic marker GFAP was reduced, and insoluble ␤-amyloid (A␤), soluble A␤, and plaque burden were significantly decreased by 43-50%. However, levels of amyloid precursor (APP) in the membrane fraction were not reduced. Microgliosis was also suppressed in neuronal layers but not adjacent to plaques. In view of its efficacy and apparent low toxicity, this Indian spice component shows promise for the prevention of Alzheimer's disease.

Research paper thumbnail of Use of Copper and Insulin-Resistance to Accelerate Cognitive Deficits and Synaptic Protein Loss in a Rat Aβ-Infusion Alzheimer's Disease Model

Journal of Alzheimer's Disease, 2008

The rat amyloid-β (Aβ) intracerebroventricular infusion can model aspects of Alzheimer's disease ... more The rat amyloid-β (Aβ) intracerebroventricular infusion can model aspects of Alzheimer's disease (AD) and has predicted efficacy of therapies such as ibuprofen and curcumin in transgenic mouse models. High density lipoprotein (HDL), a normal plasma carrier of Aβ, is used to attenuate Aβ aggregation within the pump, causing Aβ-dependent toxicity and cognitive deficits within 3 months. Our goal was to identify factors that might accelerate onset of Aβ-dependent deficits to improve efficiency and cost-effectiveness of model. We focused on: 1) optimizing HDL-Aβ preparation for maximal toxicity; 2) evaluating the role of copper, a factor typically in water that can impact oligomer stability; and 3) determining impact of insulin resistance (type II diabetes), a risk factor for AD. In vitro studies were performed to determine doses of copper and methods of Aβ-HDL preparation that maximized toxicity. These preparations when infused resulted in earlier onset of cognitive deficits within 6 weeks post-infusion. Induction of insulin resistance did not exacerbate Aβ-dependent cognitive deficits, but did exacerbate synaptic protein loss. In summary, the newly described in vivo infusion model may be useful cost-effective method for screening for new therapeutic drugs for AD.

Research paper thumbnail of PAK in Alzheimer disease, Huntington disease and X-linked mental retardation

Research paper thumbnail of Rodent models of Alzheimer's disease: Rat aβ infusion approaches to amyloid deposits

Neurobiology of Aging, 1996

Research paper thumbnail of Enrichment of presynaptic and postsynaptic markers by size-based gating analysis of synaptosome preparations from rat and human cortex

Cytometry, 2004

Background: Synapse regions in the brain are difficult to isolate and study; resealed nerve termi... more Background: Synapse regions in the brain are difficult to isolate and study; resealed nerve terminals (synaptosomes) are a widely used in vitro system for the study of neurotransmission, but nonsynaptosomal elements in the homogenate complicate data interpretation. With the goal of quantitative analysis of pathways leading to synapse loss in neurodegenerative disease, we have developed a method that allows focus on the intact synaptosomes within a crude synaptosomal preparation by gating the largest particles based on forward angle light scatter (FSC). Methods: Crude synaptosomal fractions (P-2) were prepared and labeled with a viability dye (calcein AM), a presynaptic marker (SNAP-25), and a postsynaptic marker (PSD-95). Forward scatter gates based on size standards were drawn to identify the large population (1.4-4.5 m), and the enrichment of each marker was quantified in preparations from fresh rat homogenates and from cryopreserved human cortex. Results: Gating on forward scatter resulted in an increase that was highly significant (P Ͻ 0.001) for all three markers examined. The calcein-AM-positive fraction in the large synaptosomes was 98% Ϯ 0.8, and 75% Ϯ 9.8 for rat and human, respectively. Of large particles, 90% Ϯ 2.7 in rat and 82% Ϯ 2.6 in human were positive for SNAP-25, indicating a relatively pure population of intact synaptosomes. A total of 76% Ϯ 2.9 of the large particles were positive for PSD-95 in rat. This compared to 36% Ϯ 3.0 in human tissue, and indicates that both presynaptic and postsynaptic elements may be analyzed with this methodology. Conclusions: Most nonsynaptosomal elements can be excluded and the intact subpopulation of interest within the P-2 can be identified based on size. Size-based gating analysis provides a simple and cost-effective method to monitor fluorescence changes in synapse regions.

Research paper thumbnail of Loss of MAP Function Leads to Hippocampal Synapse Loss and Deficits in the Morris Water Maze with Aging

Journal of Neuroscience, 2014

Hyperphosphorylation and accumulation of tau aggregates are prominent features in tauopathies, in... more Hyperphosphorylation and accumulation of tau aggregates are prominent features in tauopathies, including Alzheimer's disease, but the impact of loss of tau function on synaptic and cognitive deficits remains poorly understood. We report that old (19-20 months; OKO) but not middle-aged (8-9 months; MKO) tau knockout mice develop Morris Water Maze (MWM) deficits and loss of hippocampal acetylated ␣-tubulin and excitatory synaptic proteins. Mild motor deficits and reduction in tyrosine hydroxylase (TH) in the substantia nigra were present by middle age, but did not affect MWM performance, whereas OKO mice showed MWM deficits paralleling hippocampal deficits. Deletion of tau, a microtubule-associated protein (MAP), resulted in increased levels of MAP1A, MAP1B, and MAP2 in MKO, followed by loss of MAP2 and MAP1B in OKO. Hippocampal synaptic deficits in OKO mice were partially corrected with dietary supplementation with docosahexaenoic acid (DHA) and both MWM and synaptic deficits were fully corrected by combining DHA with ␣-lipoic acid (ALA), which also prevented TH loss. DHA or DHA/ALA restored phosphorylated and total GSK3␤ and attenuated hyperactivation of the tau C-Jun N-terminal kinases (JNKs) while increasing MAP1B, dephosphorylated (active) MAP2, and acetylated ␣-tubulin, suggesting improved microtubule stability and maintenance of active compensatory MAPs. Our results implicate the loss of MAP function in ageassociated hippocampal deficits and identify a safe dietary intervention, rescuing both MAP function and TH in OKO mice. Therefore, in addition to microtubule-stabilizing therapeutic drugs, preserving or restoring compensatory MAP function may be a useful new prevention strategy.

Research paper thumbnail of A Diet Enriched with the Omega-3 Fatty Acid Docosahexaenoic Acid Reduces Amyloid Burden in an Aged Alzheimer Mouse Model

Journal of Neuroscience, 2005

Epidemiological studies suggest that increased intake of the omega-3 (n-3) polyunsaturated fatty ... more Epidemiological studies suggest that increased intake of the omega-3 (n-3) polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) is associated with reduced risk of Alzheimer's disease (AD). DHA levels are lower in serum and brains of AD patients, which could result from low dietary intake and/or PUFA oxidation. Because effects of DHA on Alzheimer pathogenesis, particularly on amyloidosis, are unknown, we used the APPsw (Tg2576) transgenic mouse model to evaluate the impact of dietary DHA on amyloid precursor protein (APP) processing and amyloid burden. Aged animals (17-19 months old) were placed in one of three groups until 22.5 months of age: control (0.09% DHA), low-DHA (0%), or high-DHA (0.6%) chow. ␤-Amyloid (A␤) ELISA of the detergent-insoluble extract of cortical homogenates showed that DHA-enriched diets significantly reduced total A␤ by Ͼ70% when compared with low-DHA or control chow diets. Dietary DHA also decreased A␤42 levels below those seen with control chow. Image analysis of brain sections with an antibody against A␤ (amino acids 1-13) revealed that overall plaque burden was significantly reduced by 40.3%, with the largest reductions (40-50%) in the hippocampus and parietal cortex. DHA modulated APP processing by decreasing both ␣and ␤-APP C-terminal fragment products and full-length APP. BACE1 (␤-secretase activity of the ␤-site APP-cleaving enzyme), ApoE (apolipoprotein E), and transthyretin gene expression were unchanged with the high-DHA diet. Together, these results suggest that dietary DHA could be protective against ␤-amyloid production, accumulation, and potential downstream toxicity.