Where Does Beta Amyloid Protein Come From

Staving Off Alzheimer’s Disease With The Right Diet Prescriptions

Alzheimer’s Disease: How Does Beta Amyloid Affect the Synapse?
Date:
Society for Neuroscience
Summary:
New studies reveal the effects of environmental substances on the promotion or slowing of symptoms associated with Alzheimer’s disease. Drug screening has identified three antihypertension drugs capable of preventing Alzheimer’s-like degeneration of nerve cells in the brain. Fish oil elevated the level of a protein that prevents the formation of amyloid, the tell-tale protein found in Alzheimer’s. Caffeine reversed memory impairment in animal models of the disease. In addition, environmental copper reduced the clearance of amyloid, from the brain to blood.

New studies reveal the effects of environmental substances on the promotion or slowing of symptoms associated with Alzheimer’s disease. Drug screening has identified three antihypertension drugs capable of preventing Alzheimer’s-like degeneration of nerve cells in the brain. Fish oil elevated the level of a protein that prevents the formation of amyloid, the tell-tale protein found in Alzheimer’s. Caffeine reversed memory impairment in animal models of the disease. In addition, environmental copper reduced the clearance of amyloid, from the brain to blood.

“If we can deliver certain antihypertensive drugs at doses that do not affect blood pressure, these drugs could be made available for all members of the geriatric population identified as being at high risk for developing Alzheimer’s disease,” Pasinetti says.

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Cellular Regulation Of App Exposure To

We then investigated the ability of apoE to mediate the delivery of cholesterol to cell membranes and regulate A production in N2a cells. We applied 4 µg/mL human apoE isoform 3 , purified from E. coli with and without cholesterol, and measured APP localization to lipid clusters with dSTORM. We found that when ApoE loaded cholesterol into cells , APP association with GM1 domains was almost twofold higher than when apoE effluxed cholesterol . In a control experiment, FBS alone did not increase APP trafficking to lipid clusters , confirming that apoE is a specific and necessary mediator of cholesterol transport to the neuron. This result also confirms previous mass spectrometry results that there is no appreciable apoE in FBSif apoE were already present, then adding more would not have had such a dramatic effect. Moreover, apoE alone decreased APP clustering , confirming that exogenously added apoE can unload cholesterol in neuronal membranes. ApoE efflux was similar to MCD treatment .

Key Biological Processes In The Brain

Most neurons have three basic parts: a cell body, multiple dendrites, and an axon.

  • The cell body contains the nucleus, which houses the genetic blueprint that directs and regulates the cells activities.
  • Dendrites are branch-like structures that extend from the cell body and collect information from other neurons.
  • The axon is a cable-like structure at the end of the cell body opposite the dendrites and transmits messages to other neurons.

The function and survival of neurons depend on several key biological processes:

Neurons are a major player in the central nervous system, but other cell types are also key to healthy brain function. In fact, glial cells are by far the most numerous cells in the brain, outnumbering neurons by about 10 to 1. These cells, which come in various formssuch as microglia, astrocytes, and oligodendrocytessurround and support the function and healthy of neurons. For example, microglia protect neurons from physical and chemical damage and are responsible for clearing foreign substances and cellular debris from the brain. To carry out these functions, glial cells often collaborate with blood vessels in the brain. Together, glial and blood vessel cells regulate the delicate balance within the brain to ensure that it functions at its best.

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Scientists Reveal How Beta

Carla Shatz led a study that suggests Alzheimer’s disease may begin to manifest long before the development of placques that lead to nerve cell death.

    Stanford Medicine integrates research, medical education and health care at its three institutions – Stanford University School of Medicine, Stanford Health Care , and Lucile Packard Children’s Hospital Stanford. For more information, please visit the Office of Communication & Public Affairs site at .

    Can You Live A Normal Life With Amyloidosis

    Does Abnormal Amyloid Cause Alzheimers

    There is no cure for patients with AL amyloidosis but more frequently patients can go into remission with drug therapy. In our experience, the majority of patients surviving the first six months can often start recovering thereafter and can typically live normal or near normal lives for years to come.

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    D The App Intracellular Domain

    The high degree of sequence conservation between the intracellular domains of APP proteins predicts that it is a critical domain mediating APP function. Indeed, this relatively short cytoplasmic domain of 47 amino acid residues contains one well described phosphorylation site as well as multiple functional motifs and multiple binding partners that contribute to trafficking, metabolism, and possibly cell signaling functions of APP.

    a) Phosphorylation and Protein-Protein Interaction

    In addition to Thr668 phosphorylation, the highly conserved APP intracellular domain has been shown to bind to numerous proteins . Of particular interest and relevance to this review, the Y682ENPTY motif is required to interact with various adaptor proteins, including Mint-1/X11a , Fe65 and c-Jun N-terminal kinase -interacting protein , through the phosphotyrosine-binding domain. The Y682 has been shown to modulate APP processing in vivo . Of interest is the finding that Fe65 acts as a functional linker between APP and LRP in modulating endocytic APP trafficking and amyloidogenic processing .

    b) Apoptosis

    c) Cell Signaling

    A Interactions With Receptors

    Ryanodine receptors are expressed in the soma, proximal dendrites, and distal processes and spines of neuronal cells . It has been shown that A increases the expression and activity of ryanodine receptor 3 and subsequently these receptors disrupt intracellular Ca2+ levels. The disruption of intracellular Ca2+ homeostasis may have a role in AD pathology .

    Also, N-methyl-D-aspartate receptor stimulation and intracellular signaling of AMPA receptor trafficking are influenced by the soluble form of A . A interacts with NMDA receptors, which are responsible for maintaining glutamate homeostasis within the neurons. Dysregulation of this hemostasis may lead to excitotoxicity and impacts on the neuronal plasticity .

    LRP1 is a transmembrane protein which acts as a signaling receptor and cargo transporter. It has some essential neural functions, including the process of APP and modulation of the toxicity of the resulting A. Furthermore, LPR1 modulates NMDA receptor function . LRP1 and its ligands, ApoE and 2-macroglobulin, are involved in A deposition through sequestration and removal of its soluble forms .

    CD36 is an innate immunity receptor which is present in endothelial cells and microglia. It binds to A and activates reactive oxygen species production, vasoconstriction, and vascular tone dysregulation. Collectively, these events may provoke neuronal damage in disease progress .

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    Where Does Amyloid Come From

    Amyloid is formed from proteins large, complex molecules that are built from hundreds or thousands of smaller units called amino acids. These amino acids are joined together to form a protein chain, which then folds upon itself to produce a three-dimensional structure. The arrangement of amino acids within the protein determines where and how the protein will fold, and the final shape of the protein determines what its function within the body will be. The video below depicts a protein folding as it is being built from its constituent amino acids by a ribosome.

    Normal, healthy proteins will not aggregate to form amyloid. Unfortunately, with millions upon millions of copies of a given protein being made during our lifetimes, the folding process doesnt always occur correctly. When a protein misfolds and assumes the wrong shape, it may not properly fulfil its function, and may even become harmful. To minimise this occurrence, our cells have evolved a complex quality control system to correct or remove misfolded proteins. However, these systems become less effective as we age, allowing more and more errors to slip through the net. Once-healthy proteins can also misfold or partially unfold at some time after they have been made and released from a cell.

    37 human amyloid proteins have so far been confirmed to be capable of causing disease. Well known examples include amyloid in Alzheimers disease, -synuclein in Parkinsons disease, and huntingtin in Huntingtons disease.

    Ad Risk Factors Apoe4 And Trem2

    What are Beta-Amyloids plaques?

    Apolipoprotein E is one of the major apolipoproteins . The ApoE gene has three alleles, 2, 3, and 4, corresponding to isoforms E2, E3, and E4, respectively. In the central nervous system, ApoE produced and secreted by astrocytes and microglia binds to lipoprotein and is taken up into nerve cells via the ApoE receptor during the developmental stage of the central nervous system and the repair period after neuronal damage.

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    Reconsideration Of Amyloid Hypothesis And Tau Hypothesis In Alzheimer’s Disease

    • Department of Dementia and Higher Brain Function, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan

    The so-called amyloid hypothesis, that the accumulation and deposition of oligomeric or fibrillar amyloid peptide is the primary cause of Alzheimer’s disease , has been the mainstream concept underlying AD research for over 20 years. However, all attempts to develop A-targeting drugs to treat AD have ended in failure. Here, we review recent findings indicating that the main factor underlying the development and progression of AD is tau, not A, and we describe the deficiencies of the amyloid hypothesis that have supported the emergence of this idea.

    Animal Models Related With A For Ad

    Various types of animal models related to A have been created to dissect the mechanisms for the development and progression of AD, the majority are overexpression transgenic lines .

    TABLE 1C.Summary for A related transgenic animal models.

    Despite the existing innate disadvantages. e.g., the transgenic flies that express both human APP and -secretase BACE1 displayed A accumulation, the animal models are useful to screen genes involved in APP processing , making a great contribution to the development of this field. The secreted-A model in Drosophila is a direct approach to investigate the toxicity caused by A . The Caenorhabditis elegans A-expressing models developed in different tissues are also helpful for examining genes involved in A-induced toxicity . Phenotypes were also analyzed in zebrafish through high-throughout screen by treatment with Alzheimers -secretase inhibitors to determine efficient compounds for blocking A generation .

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    Post Mortem Or In Tissue Biopsies

    Amyloid beta can be measured semiquantitatively with immunostaining, which also allows one to determine location. Amyloid beta may be primarily vascular, as in cerebral amyloid angiopathy, or in amyloid plaques in white matter.

    One sensitive method is ELISA which is an immunosorbent assay which utilizes a pair of antibodies that recognize amyloid beta.

    Atomic force microscopy, which can visualize nanoscale molecular surfaces, can be used to determine the aggregation state of amyloid beta in vitro.

    Vibrational microspectroscopy is a label-free method that measures the vibration of molecules in tissue samples. Amyloid proteins like A can be detected with this technique because of their high content of -sheet structures. Recently, the formation of A fibrils was resolved in different plaque-types in Alzheimers disease, indicating that plaques transit different stages in their development.

    Dual polarisation interferometry is an optical technique which can measure early stages of aggregation by measuring the molecular size and densities as the fibrils elongate. These aggregate processes can also be studied on lipid bilayer constructs.

    Synaptic Formation And Repair

    Beta Amyloid Protein, Plaque i Alzheimerov

    The most-substantiated role for APP is in synaptic formation and repair its is during neuronal and after neural injury. Roles in , , and have been proposed and supported by as-yet limited research. In particular, similarities in post-translational processing have invited comparisons to the signaling role of the surface protein .

    APP are viable and have relatively minor effects including impaired long-term potentiation and memory loss without general neuron loss. On the other hand, transgenic mice with upregulated APP expression have also been reported to show impaired long-term potentiation.

    The logical inference is that because A accumulates excessively in Alzheimers disease its precursor, APP, would be elevated as well. However, neuronal cell bodies contain less APP as a function of their proximity to amyloid plaques. The data indicate that this deficit in APP results from a decline in production rather than an increase in catalysis. Loss of a neurons APP may affect physiological deficits that contribute to dementia.

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    Causes Of Alzheimers Disease

    Alzheimers disease is a progressive neurodegenerative disorder that is characterized by declining mental abilities that affect memory, cognitive function, and personality. It is the most common cause of dementia.

    While its exact cause remains unknown, many risk factors contribute to the likelihood of developing the disorder.

    Changes To Make In Your Diet

    Avoid completely foods and drinks that especially encourage the build up of amyloid protein such as refined sugars found in soft drinks, desserts, sodas, many baked goods and candies. Also avoid caffeine, found in coffee and tea and many other drinks. Avoid most refined dairy products. Food additives such as monosodium glutamate, flavorings, colorings and other chemicals are best avoided.

    Limit your consumption of meats, particularly red meats. Limit or avoid processed food to improve health and build resistance to disease. Processed foods generally contain ingredients and additives that encourage amyloid protein buildup in the body.

    Eat the standard, healthy foods such as fresh fruit, vegetables, cold-water fish and seeds such as sesame, sunflower and flax seed. Include nuts such as walnuts, almonds, pecans and hazelnuts. Add whole grains such as brown rice, buckwheat, millet, quinoa, oats and barley they are all rich in vitamins and minerals and should be included as a staple part of the diet.

    Tips

    Changing to a new diet is best done in stages, not giving up everything all at once and eating completely different foods from one day to the next. Setting yourself realistic, daily, weekly and monthly goals and sticking to them usually guarantees success in a less traumatic way, particularly if you have been used to eating highly processed foods for a long time, in which case, a drastic change may not be the best choice.

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    How Can You Slow The Damage Caused By Copper And Iron

    The easiest way to stop damage caused by copper is to make sure you have enough zinc. And theres a simple test you can take in your home without a prescription to determine whether or not you need more zinc. Its an oral zinc test. All you need is some zinc sulfate, such as Liquid Zinc Assay . To perform the test, put a teaspoon of the zinc sulfate in your mouth for 30 seconds. If theres no taste, or if your mouth has a slight dry, mineral, furry, or sweet feel, you need more zinc. If it has an unpleasant taste, you have enough zinc. The more pleasant the taste, the greater the deficiency.

    If youre low, take 2030 mg of zinc chelate a day and re-test monthly until the zinc tastes bad. Foods high in zinc include meats , nuts, pumpkin seeds, whole grains, and legumes. So a vegetarian diet is more likely to cause high copper and low zinc.

    To assess your copper, iron, and zinc levels, you can have a Tissue Mineral Analysis conducted. This hair analysis measures minerals and toxic metals and discusses environmental and dietary sources of all imbalances. Your health care practitioner may offer this test, which runs around $190. Or you can get it from Unikey .

    Isoform Specificity Of Apoe

    Amyloid Beta Processing

    As mentioned, the apoE4 isoform is a strong genetic risk factor for late onset AD. If this effect is in part through cholesterol loading, we would expect to see a difference in APPs submembrane localization. To study the difference between apoE3 and apoE4 in vivo, we analyzed the brain tissue from APOE knock in mice, in which the human APOE variants replace the endogenous murine Apoe locus . We assessed these mice both alone and after crossing them with mice with amyloid deposition in the brain by crossing the different APOE-KI mice with APP/PS1 transgenic mice. We found that an increased association of APP with GM1 lipids in E4F compared to E3F . Interestingly, overexpression of mutant APP and mutant PS1 with resulting amyloid deposition has an even more dramatic effect than APOE genotype. Brain tissue from APP/PS1 mice has significantly increased APP-GM1 association . We also measured the tissue cholesterol level of the brains and observed a similar trend, as we found in APP-GM1 pair correlation. Though not statistically significant, the E4F brains have a slightly higher cholesterol level than E3F brains . Similarly, the APP/PS1/E4F brains have a slightly higher cholesterol level than APP/PS1/E3F brains . APP/PS1 overexpression robustly increases brain tissue cholesterol level .

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    What Occurs When Beta Amyloid Precursor Protein Goes Awry

    What occurs when beta amyloid precursor protein goes awry?

    How does amyloid precursor protein work? Little is known about the function of amyloid precursor protein. Researchers speculate that it may bind to other proteins on the surface of cells or help cells attach to one another. Studies suggest that in the brain, it helps direct the movement of nerve cells during early development.

    What does over production of the amyloid protein do? Amyloidosis is a condition in which too much of a particular protein collects in the organs, so that they are not able to work normally. Amyloidosis can affect the heart, kidneys, liver, spleen, nervous system, stomach or intestines.

    What is the half life of amyloid precursor protein? Total cellular APP has previously been shown to have a short half-life of approximately 30-60 min.

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