scholarly journals Modification of lipid rafts by extracellular vesicles carrying HIV-1 protein Nef induces redistribution of amyloid precursor protein and Tau, causing neuronal dysfunction

2020 ◽  
Vol 295 (38) ◽  
pp. 13377-13392
Author(s):  
Michael Ditiatkovski ◽  
Nigora Mukhamedova ◽  
Dragana Dragoljevic ◽  
Anh Hoang ◽  
Hann Low ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Amyloid Precursor Protein ◽  
Brain Tissue ◽  
Lipid Rafts ◽  
Extracellular Vesicles ◽  
Plasma Membranes ◽  
Precursor Protein ◽  
Short Term Treatment ◽  
Hiv 1

HIV-associated neurocognitive disorders (HANDs) are a frequent outcome of HIV infection. Effective treatment of HIV infection has reduced the rate of progression and severity but not the overall prevalence of HANDs, suggesting ongoing pathological process even when viral replication is suppressed. In this study, we investigated how HIV-1 protein Nef secreted in extracellular vesicles (exNef) impairs neuronal functionality. ExNef were rapidly taken up by neural cells in vitro, reducing the abundance of ABC transporter A1 (ABCA1) and thus cholesterol efflux and increasing the abundance and modifying lipid rafts in neuronal plasma membranes. ExNef caused a redistribution of amyloid precursor protein (APP) and Tau to lipid rafts and increased the abundance of these proteins, as well as of Aβ42. ExNef further potentiated phosphorylation of Tau and activation of inflammatory pathways. These changes were accompanied by neuronal functional impairment. Disruption of lipid rafts with cyclodextrin reversed the phenotype. Short-term treatment of C57BL/6 mice with either purified recombinant Nef or exNef similarly resulted in reduced abundance of ABCA1 and elevated abundance of APP in brain tissue. The abundance of ABCA1 in brain tissue of HIV-infected human subjects diagnosed with HAND was lower, and the abundance of lipid rafts was higher compared with HIV-negative individuals. Levels of APP and Tau in brain tissue correlated with the abundance of Nef. Thus, modification of neuronal cholesterol trafficking and of lipid rafts by Nef may contribute to early stages of neurodegeneration and pathogenesis in HAND.

scholarly journals Regulation of beta-amyloid production in neurons by astrocyte-derived cholesterol

2020 ◽  
Author(s):  
Hao Wang ◽  
Joshua A. Kulas ◽  
Heather A. Ferris ◽  
Scott B. Hansen
Keyword(s):  
Amyloid Precursor Protein ◽  
Lipid Rafts ◽  
Cholesterol Synthesis ◽  
Protein Localization ◽  
Super Resolution ◽  
Precursor Protein ◽  
Targeted Deletion ◽  
Amyloid Aβ

ABSTRACTAlzheimer’s Disease (AD) is characterized by the presence of β-Amyloid (Aβ) plaques, tau tangles, inflammation, and loss of cognitive function. Genetic variation in a cholesterol transport protein, apolipoprotein E (apoE), is the most common genetic marker for sporadic AD. In vitro evidence suggests apoE links to Aβ production through nanoscale lipid compartments (also called lipid rafts), but its regulation in vivo is unclear. Here we use super-resolution imaging in mouse brain to show apoE utilizes astrocyte-derived cholesterol to specifically traffic neuronal amyloid precursor protein (APP) into lipid rafts where it interacts with β- and γ-secretases to generate Aβ-peptide. We find that targeted deletion of astrocyte cholesterol synthesis robustly reduces amyloid and tau burden in a mouse model of AD. Treatment with cholesterol-free apoE or knockdown of cholesterol synthesis in astrocytes decreases cholesterol levels in cultured neurons and causes APP to traffic out of lipid rafts where it interacts with α-secretase and gives rise to soluble APPα (sAPPα), a neuronal protective product of APP. Changes in cellular cholesterol have no effect on α-, β-, and γ-secretase trafficking, suggesting the ratio of Aβ to sAPPα is regulated by the trafficking of the substrate, not the enzymes. Treatment of astrocytes with inflammatory cytokines IL-1β, IL-6 and TNF-α upregulates the synthesis of cholesterol in the astrocytes. We conclude that cholesterol is kept low in neurons to inhibit Aβ formation and enable astrocyte regulation of Aβ formation by cholesterol regulation.HighlightsApoE regulates amyloid precursor protein localization to rafts and its exposure to α-vs. β-secretase.α-, β-, and γ-Secretases are activated by substrate presentation.ApoE specifically transports astrocyte cholesterol to neurons.Astrocyte cholesterol synthesis disruption prevents Alzheimer’s-associated amyloid pathology in mice.

scholarly journals Nitrous Oxide Plus Isoflurane Induces Apoptosis and Increases β-Amyloid Protein Levels

2009 ◽  
Vol 111 (4) ◽  
pp. 741-752 ◽  
Author(s):  
Yu Zhen ◽  
Yuanlin Dong ◽  
Xu Wu ◽  
Zhipeng Xu ◽  
Yan Lu ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Amyloid Precursor Protein ◽  
Caspase 3 ◽  
Precursor Protein ◽  
Primary Neurons ◽  
Gamma Secretase ◽  
Protein Levels ◽  
Secretase Inhibitor

Background Some anesthetics have been suggested to induce neurotoxicity, including promotion of Alzheimer's disease neuropathogenesis. Nitrous oxide and isoflurane are common anesthetics. The authors set out to assess the effects of nitrous oxide and/or isoflurane on apoptosis and beta-amyloid (Abeta) levels in H4 human neuroglioma cells and primary neurons from naïve mice. Methods The cells or neurons were exposed to 70% nitrous oxide and/or 1% isoflurane for 6 h. The cells or neurons and conditioned media were harvested at the end of the treatment. Caspase-3 activation, apoptosis, processing of amyloid precursor protein, and Abeta levels were determined. Results Treatment with a combination of 70% nitrous oxide and 1% isoflurane for 6 h induced caspase-3 activation and apoptosis in H4 naïve cells and primary neurons from naïve mice. The 70% nitrous oxide plus 1% isoflurane, but neither alone, for 6 h induced caspase-3 activation and apoptosis, and increased levels of beta-site amyloid precursor protein-cleaving enzyme and Abeta in H4-amyloid precursor protein cells. In addition, the nitrous oxide plus isoflurane-induced Abeta generation was reduced by a broad caspase inhibitor, Z-VAD. Finally, the nitrous oxide plus isoflurane-induced caspase-3 activation was attenuated by gamma-secretase inhibitor L-685,458, but potentiated by exogenously added Abeta. Conclusion These results suggest that the common anesthetics nitrous oxide plus isoflurane may promote neurotoxicity by inducing apoptosis and increasing Abeta levels. The generated Abeta may further potentiate apoptosis to form another round of apoptosis and Abeta generation. More studies, especially the in vivo confirmation of these in vitro findings, are needed.

scholarly journals SPON1 Can Reduce Amyloid Beta and Reverse Cognitive Impairment and Memory Dysfunction in Alzheimer’s Disease Mouse Model

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1275
Author(s):  
Soo Yong Park ◽  
Joo Yeong Kang ◽  
Taehee Lee ◽  
Donggyu Nam ◽  
Chang-Jin Jeon ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Amyloid Precursor Protein ◽  
Amyloid Beta ◽  
Physiological Activity ◽  
Precursor Protein ◽  
Age Related

Alzheimer’s disease (AD) is a complex, age-related neurodegenerative disease that is the most common form of dementia. However, the cure for AD has not yet been founded. The accumulation of amyloid beta (Aβ) is considered to be a hallmark of AD. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), also known as beta secretase is the initiating enzyme in the amyloidogenic pathway. Blocking BACE1 could reduce the amount of Aβ, but this would also prohibit the other functions of BACE1 in brain physiological activity. SPONDIN1 (SPON1) is known to bind to the BACE1 binding site of the amyloid precursor protein (APP) and blocks the initiating amyloidogenesis. Here, we show the effect of SPON1 in Aβ reduction in vitro in neural cells and in an in vivo AD mouse model. We engineered mouse induced neural stem cells (iNSCs) to express Spon1. iNSCs harboring mouse Spon1 secreted SPON1 protein and reduced the quantity of Aβ when co-cultured with Aβ-secreting Neuro 2a cells. The human SPON1 gene itself also reduced Aβ in HEK 293T cells expressing the human APP transgene with AD-linked mutations through lentiviral-mediated delivery. We also demonstrated that injecting SPON1 reduced the amount of Aβ and ameliorated cognitive dysfunction and memory impairment in 5xFAD mice expressing human APP and PSEN1 transgenes with five AD-linked mutations.

scholarly journals Hyperbaric hyperoxia exposure in suppressing human immunodeficiencyvirus replication: An experimental in vitro in peripheral mononuclear blood cells culture

2020 ◽  
Author(s):  
Retno Budiarti ◽  
Siti Qamariyah Khairunisa ◽  
Nasronudin ◽  
Kuntaman ◽  
Guritno
Keyword(s):  
Hiv Infection ◽  
Healthy Volunteers ◽  
Hyperbaric Oxygen ◽  
Experimental Unit ◽  
Control Group ◽  
P24 Antigen ◽  
Hyperbaric Exposure ◽  
Interferon Α2 ◽  
Hiv 1

Cellular immune has an important role in response HIV infection, which is attack the infected cells to activate signaling molecule. Hyperbaric Oxygen (HBO) worked as complementary treatment for HIV infection. The production of ROS and RNS molecules during hyperbaric exposure can affect gene expression which contributes to cellular adaptative response. This study was conducted to explore the mechanisms of cellular adaptive response to HIV infection during hyperbaric exposure. This study was carried on in vitro using healthy volunteers’ PBMCs (Peripheral Blood Mononuclear Cells) cultures infected with HIV-1. The study was conducted as a post- test only group design. The experimental unit was PBMC from venous blood of healthy volunteers which were cultured in vitro and infected by co-culturing with HIV-1 in MT4 cell line. The experimental unit consist of treatment and control group. Each group examined the expression of transcription factor NFκB, Interferon α, reverse transcriptase inhibitors (p21), and the amount of HIV-1 p24 antigen. There were increasingly significant differences in the expression of the trancription factor of NFκB, p21, and HIV-1 p24 antigen,as well as mRNA transcription of interferon α2 between treatment and controlgroup. By decreasing p24 antigen showed that HBO exposure was able to suppress HIV-1 replication. The exposure to hyperbaric oxygen at the pressure of 2.4 ATAand 98% oxygen wasable to produce ROS and RNS molecules, which play a role in cellular adaptive responses through increasing the expression of nfĸb, p21 and mRNA of interferon α2 plays a role in inhibition mechanism of HIV-1 replication in cells.

scholarly journals Presenilin 1 Controls γ-Secretase Processing of Amyloid Precursor Protein in Pre-Golgi Compartments of Hippocampal Neurons

1999 ◽  
Vol 147 (2) ◽  
pp. 277-294 ◽  
Author(s):  
Wim G. Annaert ◽  
Lyne Levesque ◽  
Kathleen Craessaerts ◽  
Inge Dierinck ◽  
Greet Snellings ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Amyloid Precursor Protein ◽  
Hippocampal Neurons ◽  
Subcellular Fractionation ◽  
Precursor Protein ◽  
Presenilin 1 ◽  
Carboxy Terminal ◽  
Endocytic Pathways

Mutations of presenilin 1 (PS1) causing Alzheimer's disease selectively increase the secretion of the amyloidogenic βA4(1-42), whereas knocking out the gene results in decreased production of both βA4(1-40) and (1-42) amyloid peptides (De Strooper et al. 1998). Therefore, PS1 function is closely linked to the γ-secretase processing of the amyloid precursor protein (APP). Given the ongoing controversy on the subcellular localization of PS1, it remains unclear at what level of the secretory and endocytic pathways PS1 exerts its activity on APP and on the APP carboxy-terminal fragments that are the direct substrates for γ-secretase. Therefore, we have reinvestigated the subcellular localization of endogenously expressed PS1 in neurons in vitro and in vivo using confocal microscopy and fine-tuned subcellular fractionation. We show that uncleaved PS1 holoprotein is recovered in the nuclear envelope fraction, whereas the cleaved PS fragments are found mainly in post-ER membranes including the intermediate compartment (IC). PS1 is concentrated in discrete sec23p- and p58/ERGIC-53–positive patches, suggesting its localization in subdomains involved in ER export. PS1 is not found to significant amounts beyond the cis-Golgi. Surprisingly, we found that APP carboxy-terminal fragments also coenrich in the pre-Golgi membrane fractions, consistent with the idea that these fragments are the real substrates for γ-secretase. Functional evidence that PS1 exerts its effects on γ-secretase processing of APP in the ER/IC was obtained using a series of APP trafficking mutants. These mutants were investigated in hippocampal neurons derived from transgenic mice expressing PS1wt or PS1 containing clinical mutations (PS1M146L and PS1L286V) at physiologically relevant levels. We demonstrate that the APP-London and PS1 mutations have additive effects on the increased secretion of βA4(1-42) relative to βA4(1-40), indicating that both mutations operate independently. Overall, our data clearly establish that PS1 controls γ42-secretase activity in pre-Golgi compartments. We discuss models that reconcile this conclusion with the effects of PS1 deficiency on the generation of βA4(1-40) peptide in the late biosynthetic and endocytic pathways.

Racemic N1-Norphenserine and Its Enantiomers: Unpredicted Inhibition of Human Acetyl- and Butyrylcholinesterase and β-Amyloid Precursor Protein in vitro

Heterocycles ◽  
2003 ◽  
Vol 61 (1) ◽  
pp. 529 ◽  
Author(s):  
Nigel H. Greig ◽  
Qian-sheng Yu ◽  
Weiming Luo ◽  
Harold W. Holloway ◽  
Tada Utsuki ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Precursor Protein ◽  
Β Amyloid

scholarly journals Preferential infection and depletion of Mycobacterium tuberculosis–specific CD4 T cells after HIV-1 infection

2010 ◽  
Vol 207 (13) ◽  
pp. 2869-2881 ◽  
Author(s):  
Christof Geldmacher ◽  
Njabulo Ngwenyama ◽  
Alexandra Schuetz ◽  
Constantinos Petrovas ◽  
Klaus Reither ◽  
...  
Keyword(s):  
T Cells ◽  
Mycobacterium Tuberculosis ◽  
Hiv Infection ◽  
Cd4 T Cells ◽  
Staphylococcal Enterotoxin B ◽  
Opportunistic Pathogens ◽  
Rapid Loss ◽  
Hiv 1

HIV-1 infection results in the progressive loss of CD4 T cells. In this study, we address how different pathogen-specific CD4 T cells are affected by HIV infection and the cellular parameters involved. We found striking differences in the depletion rates between CD4 T cells to two common opportunistic pathogens, cytomegalovirus (CMV) and Mycobacterium tuberculosis (MTB). CMV-specific CD4 T cells persisted after HIV infection, whereas MTB-specific CD4 T cells were depleted rapidly. CMV-specific CD4 T cells expressed a mature phenotype and produced very little IL-2, but large amounts of MIP-1β. In contrast, MTB-specific CD4 T cells were less mature, and most produced IL-2 but not MIP-1β. Staphylococcal enterotoxin B–stimulated IL-2–producing cells were more susceptible to HIV infection in vitro than MIP-1β–producing cells. Moreover, IL-2 production was associated with expression of CD25, and neutralization of IL-2 completely abrogated productive HIV infection in vitro. HIV DNA was found to be most abundant in IL-2–producing cells, and least abundant in MIP-1β–producing MTB-specific CD4 T cells from HIV-infected subjects with active tuberculosis. These data support the hypothesis that differences in function affect the susceptibility of pathogen-specific CD4 T cells to HIV infection and depletion in vivo, providing a potential mechanism to explain the rapid loss of MTB-specific CD4 T cells after HIV infection.

scholarly journals Beta secretase 1-dependent amyloid precursor protein processing promotes excessive vascular sprouting through NOTCH3 signalling

2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Claire S. Durrant ◽  
Karsten Ruscher ◽  
Olivia Sheppard ◽  
Michael P. Coleman ◽  
Ilknur Özen
Keyword(s):  
Amyloid Precursor Protein ◽  
Precursor Protein ◽  
Vascular Pathology ◽  
Amyloid Precursor Protein Processing ◽  
Amyloid Beta Peptides ◽  
App Processing ◽  
Sprouting Angiogenesis ◽  
Organotypic Brain Slice ◽  
Bace1 Inhibition

AbstractAmyloid beta peptides (Aβ) proteins play a key role in vascular pathology in Alzheimer’s Disease (AD) including impairment of the blood–brain barrier and aberrant angiogenesis. Although previous work has demonstrated a pro-angiogenic role of Aβ, the exact mechanisms by which amyloid precursor protein (APP) processing and endothelial angiogenic signalling cascades interact in AD remain a largely unsolved problem. Here, we report that increased endothelial sprouting in human-APP transgenic mouse (TgCRND8) tissue is dependent on β-secretase (BACE1) processing of APP. Higher levels of Aβ processing in TgCRND8 tissue coincides with decreased NOTCH3/JAG1 signalling, overproduction of endothelial filopodia and increased numbers of vascular pericytes. Using a novel in vitro approach to study sprouting angiogenesis in TgCRND8 organotypic brain slice cultures (OBSCs), we find that BACE1 inhibition normalises excessive endothelial filopodia formation and restores NOTCH3 signalling. These data present the first evidence for the potential of BACE1 inhibition as an effective therapeutic target for aberrant angiogenesis in AD.

Neurotrophic effects of amyloid precursor protein peptide 165 in vitro

2016 ◽  
Vol 120 ◽  
pp. 58-62
Author(s):  
Jie Yao ◽  
Lina Ma ◽  
Rong Wang ◽  
Shuli Sheng ◽  
Zhijuan Ji ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Precursor Protein
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