DOCSLIB.ORG

Truncated Β-Amyloid Peptide Channels Provide an Alternative Mechanism for Alzheimer’S Disease and Down Syndrome

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Truncated Β-Amyloid Peptide Channels Provide an Alternative Mechanism for Alzheimer’S Disease and Down Syndrome Truncated β-amyloid peptide channels provide an alternative mechanism for Alzheimer’s Disease and Down syndrome Hyunbum Janga,1, Fernando Teran Arceb,1,2, Srinivasan Ramachandranb,1,2, Ricardo Caponeb,2, Rushana Azimovac, Bruce L. Kaganc, Ruth Nussinova,d,3, and Ratnesh Lalb,2,3 aCenter for Cancer Research Nanobiology Program, SAIC-Frederick, Inc., National Cancer Institute, Frederick, MD 21702; bCenter for Nanomedicine and Department of Medicine, University of Chicago, Chicago, IL 60637; cSemel Neuropsychiatric Institute, The David Geffen School of Medicine, University of California at Los Angeles and Greater Los Angeles Veterans Administration Health System, Los Angeles, CA 90024; and dDepartment of Human Molecular Genetics and Biochemistry, The Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel Edited* by Francisco Bezanilla, University of Chicago, Chicago, IL, and approved February 16, 2010 (received for review December 10, 2009) Full-length amyloid beta peptides (Aβ1–40/42) form neuritic amyloid nonamyloidogenic nature, these peptides are assumed to be plaques in Alzheimer’s disease (AD) patients and are implicated in nonpathogenic and these pathways are even being targeted for AD pathology. However, recent transgenic animal models cast doubt AD therapeutics. Significantly, p3 peptides are present in AD on their direct role in AD pathology. Nonamyloidogenic truncated amyloid plaques (17–20), are the main constituent of cerebellar amyloid-beta fragments (Aβ11–42 and Aβ17–42) are also found in amy- preamyloid lesions in Down syndrome (21) and induce neuronal loid plaques of AD and in the preamyloid lesions of Down syndrome, toxicity (22–24). However, their biophysical properties, mecha- a model system for early-onset AD study. Very little is known about nism of toxicity, and pathological significance in AD and Down the structure and activity of these smaller peptides, although they syndrome remain unclear. Similarly, very little is known about could be the primary AD and Down syndrome pathological agents. Aβ11–40/42 (16). Using complementary techniques of molecular dynamics simula- In this study, we have used molecular dynamics (MD) simu- tions, atomic force microscopy, channel conductance measurements, lations, AFM, channel-conductance measurements, cell calcium PHYSIOLOGY calcium imaging, neuritic degeneration, and cell death assays, we imaging, neurite degeneration, and cell death assays to examine show that nonamyloidogenic Aβ9–42 and Aβ17–42 peptides form ion the biophysical properties and cellular effects of these truncated channels with loosely attached subunits and elicit single-channel smaller Aβ peptides. In the present study, we restricted our conductances. The subunits appear mobile, suggesting insertion investigations to Aβ17–42 (hereafter referred as p3) and Aβ9–42 of small oligomers, followed by dynamic channel assembly and dis- (hereafter referred as N9 to indicate that they are N-terminally sociation. These channels allow calcium uptake in amyloid precursor truncated at position 9) (SI Materials and Methods). Although fi protein-de cient cells. The channel mediated calcium uptake induces Aβ11–42 is the physiological unit, its experiment-based coordinates neurite degeneration in human cortical neurons. Channel conduc- are not available. ssNMR coordinates are available for Aβ9–42 tance, calcium uptake, and neurite degeneration are selectively only. This fragment contains two more residues and is expected to inhibited by zinc, a blocker of amyloid ion channel activity. Thus, have a similar structure to that of Aβ11–42. Our results strongly truncated Aβ fragments could account for undefined roles played suggest that nonamyloidogenic peptides N9 and p3 form ion by full length Aβs and provide a unique mechanism of AD and Down channels and induce neuronal toxicity in dose-dependent fashion syndrome pathologies. The toxicity of nonamyloidogenic peptides by altering cell calcium homeostasis and could provide additional via an ion channel mechanism necessitates a reevaluation of the cur- mechanisms of AD and Down syndrome pathologies. rent therapeutic approaches targeting the nonamyloidogenic path- way as avenue for AD treatment. Results Modeling N9 and p3 Channels in the Bilayer. Early MD simulations of atomic force microscopy | molecular dynamics | cell calcium imaging | amyloidogenic peptides (5, 25) consisting of U-shaped β-strand- neurite degeneration and cell death assays | single-channel conductance turn-β-strand peptides in the bilayer predicted ion-permeable channels formed by loosely attached mobile subunits with mor- myloid-beta peptides (Aβ1–40/42) produced by β- and γ-sec- phologies and dimensions similar to the AFM-images of amyloid retase processing of amyloid precursor protein (APP) in the channels (7, 8). U-shaped motifs, first predicted by modeling of A β amyloidogenic pathway are involved in Alzheimer’s disease (AD) A 16–35 (26), appear as a general feature of amyloid organization, suggesting that other U-shaped amyloid organizations may also pathology. Aβ1–40/42 peptides form β-sheet-rich ordered aggre- gates and soluble oligomers. Small oligomers are emerging as the predominant toxic species (1–3); the toxicity is believed to be a result of the loss of ionic homeostasis, presumably via ion channels Author contributions: B.L.K., R.N., and R.L. designed research; H.J., F.T.A., S.R., R.C., and R. β A. performed research; H.J., F.T.A., S.R., R.C., B.L.K., R.N., and R.L. contributed new re- formed in cellular membranes (4, 5). EM images of A oligomers agents/analytic tools; H.J., F.T.A., S.R., R.C., R.A., B.L.K., R.N., and R.L. analyzed data; and show doughnut-like morphologies (6). Atomic force microscopic H.J., F.T.A., S.R., R.C., R.A., B.L.K., R.N., and R.L. wrote the paper. (AFM) images of Aβ peptides reconstituted in lipid bilayers show The authors declare no conflict of interest. heteromeric (rectangular to hexagonal) ion channel-like struc- *This Direct Submission article had a prearranged editor. ∼ tures with a 2.0-nm central pore and 8- to 12-nm outer diameters Freely available online through the PNAS open access option. (7, 8). Electrophysiological studies show heterodisperse cation- – Data deposition: The p3 coordinates were taken from the public database (ID: 2BEG). selective single-channel conductances (7 14) that are consistent 1 – H.J., F.T.A., and S.R. contributed equally to this work. with features of other amyloid ion channels (6 8). 2 On the other hand, when APP is cleaved by γ- and α-secretases, Present address: Department of Bioengineering and Department of Mechanical and ∼ Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093-0412. it forms the nonamyloidogenic pathway generating 2.6-kDa 3 To whom correspondence may be addressed. E-mail: [email protected] or ruthnu@helix. fragments (Aβ17–40/42) known as the p3 peptides (15). Cleavage by nih.gov. γ and BACE between Tyr10 and Glu11 generates another non- This article contains supporting information online at www.pnas.org/cgi/content/full/ amyloidogenic Aβ peptide (Aβ11–40/42) (16). Because of their 0914251107/DCSupplemental. www.pnas.org/cgi/doi/10.1073/pnas.0914251107 PNAS Early Edition | 1of6 Downloaded by guest on September 23, 2021 form dynamic ion channels in the fluidic membrane (8). Because A N9 (Aβ9-42) N9 and p3 have membrane-spanning segments, we modeled their 3D structures in the bilayer using the previous successful protocol 2 1 (5, 25). Using the two available Aβ oligomer coordinate sets (27, 3 ~1.7 nm 28), we constructed annular channels based on the U-shaped β-strand-turn-β-strand motif. Previously, U-shaped motifs were also observed in the ssNMR structure of a β2-microglobulin frag- ment (29) and in the CA150 WW domain (30), and they could also 45 ~7.3 nm form ion channels similar to prion and to β2-microglobulin (31, 32). We constructed perfectly annular channels as the starting points for the atomistic simulations with 12 to 36 monomers per channel p3 (Aβ17-42) and lipid-favorable topology (5, 25) (SI Materials and Methods). B For clarity, all modeling images presented in this article are made 2 with 16 peptides. In the modeled channels, both N9 and p3 are 1 ~1.7 nm U-shaped, although with different turn conformations. The p3 channel is embedded in the bilayer. In the pore, Glu22 side chains circularly cluster forming a negatively charged ring. The N9 chan- nel protrudes from the bilayer surface, especially at the bottom 3 4 ~6.8 nm leaflet, because the turn residues locate at the same height as the phosphate atoms at the top bilayer leaflet. In addition to the Glu22 cationic binding sites, positively charged His14 and Lys16 create p3-F19P anionic binding sites. C At t > 5 ns, these channels gradually relax through association 2 1 or dissociation of the intermolecular backbone hydrogen bonds ~0.9 nm (H-bonds) between the β-strands. Consistent with earlier obser- vations (5, 25), the channel outer β-sheet, absent in the initial structure because of the larger curvature at the channel periphery, 3 is recovered at certain regions and the channel organizes into ~6.4 nm several small subunits with or without disordered monomers in 4 between (Fig. 1 A and B). Transient inner β-sheet H-bonds barely prevent subunit dissociation and the discontinuous β-sheet net- Fig. 1. Aβ channel conformations by MD simulations. The simulated channel work can determine the boundary between the channel’s ordered structures (Left) with highlighted subunits for the N9 (A), p3 (B), and p3-F19P subunits (Fig. S1 A and B). mutant (C) channels are shown in the view along the membrane normal. The N9 channels obtain four or five ordered subunits (Fig. 1A (Center and Right) Averaged pore structures calculated by the HOLE program (50) embedded in the averaged channel conformations during the simulations.
Load more

Recommended publications
  • Amyloidogenic Processing of the Human Amyloid Precursor Protein in Primary Cultures of Rat Hippocampal Neurons
    The Journal of Neuroscience, February 1, 1996. 16(3):699-908 Amyloidogenic Processing of the Human Amyloid Precursor Protein in Primary Cultures of Rat Hippocampal Neurons Mikael Simons,1s2 Bart De Strooper, 2,s Gerd Multhaup,’ Pentti J. Tienari,l** Carlos G. Dot@* and Konrad Beyreutherl 1Center for Molecular Biology Heidelberg, University of Heidelberg, D-69 120 Heidelberg, Germany, 2Cell Biology Program, European Molecular Biology Laboratory, D-690 12 Heidelberg, Germany, and 3Center for Human Genetics, 3000 Leuven, Belgium The aim of this study was to investigate the proteolytic pro- containing C-terminal fragments (1 O-l 2 kDa) intracellularly. cessing of the amyloid precursor protein (APP) in polarized Radiosequencing showed that these fragments were created at primary cultures of hippocampal neurons. We have used the a previously described p-secretase cleavage site and at a Semliki Forest virus (SFV) vector to express human APP695 in cleavage site 12 residues from the N terminus of the pA4 hippocampal neurons, sympathetic ganglia, and glial cells. The domain (ThFa4 of APP695), which we named S-cleavage. latter two cells secrete little or no APP, whereas hippocampal Based on the observation that mature hippocampal neurons neurons secrete two forms of APP695, which differ in sialic acid produce two potentially amyloidogenic fragments and secrete content and in their kinetic appearance in the culture medium. substantial amounts of pA4 when expressing human APP, our In addition, rat hippocampal neurons expressing human APP results strengthen the hypothesis that neurons play a central produced significant amounts of the 4 kDa peptide pA4. After 3 role in the process of PA4 deposition in cases of Alzheimer’s hr of metabolic labeling, the relative amount of PA4 peptide to disease and in aged primates.
    [Show full text]
  • Reciprocal Modulation Between Amyloid Precursor Protein and Synaptic Membrane Cholesterol Revealed by Live Cell Imaging T
    Neurobiology of Disease 127 (2019) 449–461 Contents lists available at ScienceDirect Neurobiology of Disease journal homepage: www.elsevier.com/locate/ynbdi Reciprocal modulation between amyloid precursor protein and synaptic membrane cholesterol revealed by live cell imaging T Claire E. DelBovea, Claire E. Strothmanb, Roman M. Lazarenkoa, Hui Huangc, ⁎ Charles R. Sandersc,d, Qi Zhanga,e, a Department of Pharmacology, Vanderbilt University, United States of America b Department of Cell and Developmental Biology, Vanderbilt University, United States of America c Department of Biochemistry, Vanderbilt University, United States of America d Department of Medicine, Vanderbilt University Medical Center, United States of America e Brain Institute, Florida Atlantic University, United States of America ARTICLE INFO ABSTRACT Keywords: The amyloid precursor protein (APP) has been extensively studied because of its association with Alzheimer's Amyloid precursor protein disease (AD). However, APP distribution across different subcellular membrane compartments and its function Trafficking in neurons remains unclear. We generated an APP fusion protein with a pH-sensitive green fluorescent protein at Proteolysis its ectodomain and a pH-insensitive blue fluorescent protein at its cytosolic domain and used it to measure APP's Membrane distribution, subcellular trafficking, and cleavage in live neurons. This reporter, closely resembling endogenous Cholesterol APP, revealed only a limited correlation between synaptic activities and APP trafficking. However, the synaptic Synapse surface fraction of APP was increased by a reduction in membrane cholesterol levels, a phenomenon that in- volves APP's cholesterol-binding motif. Mutations at or near binding sites not only reduced both the surface fraction of APP and membrane cholesterol levels in a dominant negative manner, but also increased synaptic vulnerability to moderate membrane cholesterol reduction.
    [Show full text]
  • BACE1 Function and Inhibition: Implications of Intervention in the Amyloid Pathway of Alzheimer’S Disease Pathology
    Review BACE1 Function and Inhibition: Implications of Intervention in the Amyloid Pathway of Alzheimer’s Disease Pathology Gerald Koelsch CoMentis, Inc., South San Francisco, CA 94080, USA; [email protected] Received: 15 September 2017; Accepted: 10 October 2017; Published: 13 October 2017 Abstract: Alzheimer’s disease (AD) is a fatal progressive neurodegenerative disorder characterized by increasing loss in memory, cognition, and function of daily living. Among the many pathologic events observed in the progression of AD, changes in amyloid β peptide (Aβ) metabolism proceed fastest, and precede clinical symptoms. BACE1 (β-secretase 1) catalyzes the initial cleavage of the amyloid precursor protein to generate Aβ. Therefore inhibition of BACE1 activity could block one of the earliest pathologic events in AD. However, therapeutic BACE1 inhibition to block Aβ production may need to be balanced with possible effects that might result from diminished physiologic functions BACE1, in particular processing of substrates involved in neuronal function of the brain and periphery. Potentials for beneficial or consequential effects resulting from pharmacologic inhibition of BACE1 are reviewed in context of ongoing clinical trials testing the effect of BACE1 candidate inhibitor drugs in AD populations. Keywords: Alzheimer’s disease; amyloid hypothesis; BACE1; beta secretase; pharmacology 1. Introduction Alzheimer’s disease (AD) is a fatal progressive neurodegenerative disorder, slowly eroding memory, cognition, and functions of daily living, inevitably culminating in death from pneumonia and infectious diseases resulting from failure to thrive, loss of fine motor skills, and incapacitation. Treatment is limited to therapeutics that alleviate symptoms of memory loss, but are effective for a relatively short duration during and after which disease progression continues.
    [Show full text]
  • Γ-Secretase Inhibitors for Treating Alzheimer's Disease
    Review: Clinical Trial Outcomes g-secretase inhibitors for treating Alzheimer’s disease: rationale and clinical data Clin. Invest. (2011) 1(8), 1175–1194 There are no drugs available for slowing down the rate of deterioration Francesco Panza†1, Vincenza Frisardi2, of patients with Alzheimer’s disease (AD). With the aim of altering the Bruno P Imbimbo3, Davide Seripa1, natural history of the disease, the pharmaceutical industry has designed Vincenzo Solfrizzi2 & Alberto Pilotto4 and developed several compounds inhibiting g-secretase, the enzymatic 1Geriatric Unit & Gerontology–Geriatric Research Laboratory, IRCCS Casa Sollievo della Sofferenza, complex generating b-amyloid (Ab) peptides (Ab1–40 and Ab1–42), believed to be involved in the pathophysiological cascade of AD, from amyloid precursor Viale Cappuccini 1, 71013 San Giovanni Rotondo, protein (APP). This article briefly reviews the profile of g-secretase inhibitors Foggia, Italy 2Department of Geriatrics, Center for Aging that have reached the clinic. Studies in both transgenic and nontransgenic Brain, Memory Unit, University of Bari, Bari, Italy animal models of AD have indicated that g-secretase inhibitors, administered 3Research & Development Department, by the oral route, are able to lower brain Ab concentrations. However, Chiesi Farmaceutici, Parma, Italy few data are available on the effects of these compounds on brain Ab 4Geriatrics Unit, Azienda, ULSS 16 Padova, Italy † deposition after prolonged administration. g-secretase inhibitors may cause Author for correspondence: Tel.: +39 088 241 6260 abnormalities in the gastrointestinal tract, thymus, spleen, skin, and decrease Fax: +39 088 241 6264 in lymphocytes and alterations in hair color in experimental animals and in E-mail: [email protected] man, effects believed to be associated with the inhibition of the cleavage of Notch, a transmembrane receptor involved in regulating cell-fate decisions.
    [Show full text]
  • Amyloid Protein and Neurofibrillary Tangles Coexist in the Same Neuron
    Proc. Natl. Acad. Sci. USA Vol. 86, pp. 2853-2857, April 1989 Medical Sciences Amyloid protein and neurofibrillary tangles coexist in the same neuron in Alzheimer disease (amyloid 13 peptide/A4 peptide/intraneuronal protein/paired helical rdaments/senile plaques) INGE GRUNDKE-IQBAL*, KHALID IQBAL, LALU GEORGE, YUNN-CHYN TUNG, KWANG Soo KIM, AND HENRY M. WISNIEWSKI New York State Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314 Communicated by Philip Siekevitz, January 3, 1989 (receivedfor review July 27, 1988) ABSTRACT In Alzheimer disease, paired helical filaments tants of mAb to amyloid at dilutions of 1:2-1:20 were used accumulate in the neuron, and amyloid fibers are found in the (IgG subclass in parentheses): 4G5 (IgGi), 2B8 (IgGl), 2F9 extracellular space in the neuropil and brain vessels. Amyloid (IgGl), 4E11 (IgG2a), 4G8 (IgG2b). mAb tau-1 to tau (IgG2a, and paired helical filaments are morphologically distinct. ascites, 1:50,000) was the generous gift of L. I. Binder Although messenger RNA that encodes the amyloid has also (University of Alabama, Birmingham). Mouse ascites fluid been shown in several tissues, including brain, the intracellular from plasmacytoma line MOPC21 was purchased from Litton expression of the protein has not been observed. By using Bionetics. Reagents for the avidin-biotin complex technique monoclonal antibodies to a synthetic amyloid (3 peptide, the were purchased from Vector Laboratories, and reagents for present study demonstrates that amyloid reactivity is present in the peroxidase-anti-peroxidase technique were from Stern- both Alzheimer patients and normal individuals in different bergerMeyer Immunocytochemicals (Jarrettsville, MD).
    [Show full text]
  • The Author's Perspective
    NEWS AND VIEWS out, this concept may help explain the intrigu- Perhaps most important for current and 2. Kamenetz, F. et al. Neuron 37, 925–937 (2003). 3. Lazarov, O., Lee, M., Peterson, D.A. & Sisodia, S.S. ing observation that those brain sites prone to future patients with Alzheimer disease is the J. Neurosci. 22, 9785–9793 (2002). accumulating extracellular Aβ deposits with age concept that exploiting in vivo brain micro- 4. Sheng, J.G., Price, D.L. & Koliatsos, V.E. J. Neurosci. and in Alzheimer disease overlap with regions of dialysis to measure interstitial levels of Aβ 22, 9794–9749 (2002). so-called ‘default activity,’ that is, cortical areas peptides in APP mouse models could provide 5. Buckner, R.L. et al. J. Neurosci. 25, 7709–7717 (2005). that have high basal rates of metabolic activity (as powerful preclinical discrimination among 6. Kim, D.Y., Ingano, L.A., Carey, B.W., Pettingell, W.H. determined by functional magnetic resonance various different agents intended to decrease & Kovacs, D.M. J. Biol. Chem. 280, 23251–23261 imaging and positron emission tomography) the production or enhance the clearance of (2005). β8. 7. Nitsch, R.M., Farber, S.A., Growdon, J.H. & when an individual is not performing a specific A The use of alternative in vivo methods in Wurtman, R.J. Proc. Natl. Acad. Sci. USA 90, mental task (for example, ‘daydreaming’)5. humans9 could bring quantitative brain moni- 5191–5193 (1993). The innovative approach of Cirrito et al. toring of Aβ-lowering therapeutics to clinical 8. Selkoe, D.J. & Schenk, D.
    [Show full text]
  • RNA/Peptide Editing in Small Soluble Binding Proteins, a New Theory for the Origin of Life on Earth’S Crust
    Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 30 January 2020 RNA/peptide editing in small soluble binding proteins, a new theory for the origin of life on Earth’s crust Jean-François Picimbon QILU University of Technology, School of Bioengineering, Jinan 250353, Shandong, China Corresponding Author: Picimbon JF QILU University of Technology, School of Bioengineering Jinan 250353, Shandong, China Email: [email protected]/[email protected] Running Title: Evolutionary path from protocell to brain © 2020 by the author(s). Distributed under a Creative Commons CC BY license. Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 30 January 2020 Abstract We remind about the dogma initially established with the nucleic acid double helix, i.e. the DNA structure as the primary source of life. However, we bring into the discussion those additional processes that were crucial to enable life and cell evolution. Studying chemosensory proteins (CSPs) and odor binding proteins (OBPs) of insects, we have found a high level of pinpoint mutations on the RNA and peptide sequences. Many of these mutations are found to be tissue-specific and induce subtle changes in the protein structure, leading to a new theory of cell multifunction and life evolution. Here, attention is given to RNA and peptide mutations in small soluble protein families known for carrying lipids and fatty acids as fuel for moth cells. A new phylogenetic analysis of mutations is presented and provides even more support to the pioneer work, i.e. the finding that mutations in binding proteins have spread through moths and various groups of insects. Then, focus is given to specific mechanisms of mutations that are not random, change -helical profilings and bring new functions at the protein level.
    [Show full text]
  • Amyloid Protein and Neurofibrillary Tangles Coexist in the Same Neuron in Alzheimer Disease
    Proc. Natl. Acad. Sci. USA Vol. 86, pp. 2853-2857, April 1989 Medical Sciences Amyloid protein and neurofibrillary tangles coexist in the same neuron in Alzheimer disease (amyloid 13 peptide/A4 peptide/intraneuronal protein/paired helical rdaments/senile plaques) INGE GRUNDKE-IQBAL*, KHALID IQBAL, LALU GEORGE, YUNN-CHYN TUNG, KWANG Soo KIM, AND HENRY M. WISNIEWSKI New York State Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, NY 10314 Communicated by Philip Siekevitz, January 3, 1989 (receivedfor review July 27, 1988) ABSTRACT In Alzheimer disease, paired helical filaments tants of mAb to amyloid at dilutions of 1:2-1:20 were used accumulate in the neuron, and amyloid fibers are found in the (IgG subclass in parentheses): 4G5 (IgGi), 2B8 (IgGl), 2F9 extracellular space in the neuropil and brain vessels. Amyloid (IgGl), 4E11 (IgG2a), 4G8 (IgG2b). mAb tau-1 to tau (IgG2a, and paired helical filaments are morphologically distinct. ascites, 1:50,000) was the generous gift of L. I. Binder Although messenger RNA that encodes the amyloid has also (University of Alabama, Birmingham). Mouse ascites fluid been shown in several tissues, including brain, the intracellular from plasmacytoma line MOPC21 was purchased from Litton expression of the protein has not been observed. By using Bionetics. Reagents for the avidin-biotin complex technique monoclonal antibodies to a synthetic amyloid (3 peptide, the were purchased from Vector Laboratories, and reagents for present study demonstrates that amyloid reactivity is present in the peroxidase-anti-peroxidase technique were from Stern- both Alzheimer patients and normal individuals in different bergerMeyer Immunocytochemicals (Jarrettsville, MD).
    [Show full text]
  • Do Anti-Amyloid Beta Protein Antibody Cross Reactivities Confound Alzheimer Disease Research? Sally Hunter* and Carol Brayne
    Hunter and Brayne Journal of Negative Results in BioMedicine (2017) 16:1 DOI 10.1186/s12952-017-0066-3 MINI-REVIEW Open Access Do anti-amyloid beta protein antibody cross reactivities confound Alzheimer disease research? Sally Hunter* and Carol Brayne Abstract Background: Alzheimer disease (AD) research has focussed mainly on the amyloid beta protein (Aβ). However, many Aβ-and P3-type peptides derived from the amyloid precursor protein (APP) and peptides thought to derive from Aβ catabolism share sequence homology. Additionally, conformations can change dependent on aggregation state and solubility leading to significant uncertainty relating to interpretations of immunoreactivity with antibodies raised against Aβ. We review evidence relating to the reactivities of commonly used antibodies including 6F3D, 6E10 and 4G8 and evaluate their reactivity profiles with respect to AD diagnosis and research. Results: Antibody cross-reactivities between Aβ-type, P3-type and Aβ-catabolic peptides confound interpretations of immunoreactivity. More than one antibody is required to adequately characterise Aβ. The relationships between anti-Aβ immunoreactivity, neuropathology and proposed APP cleavages are unclear. Conclusions: We find that the concept of Aβ lacks clarity as a specific entity. Anti-Aβ antibody cross-reactivities lead to significant uncertainty in our understanding of the APP proteolytic system and its role in AD with profound implications for current research and therapeutic strategies. Keywords: Alzheimer disease, Amyloid beta protein,
    [Show full text]
  • Loss of CDC50A Function Drives Aβ/P3 Production Via Increased Β/Α-Secretase Processing Of
    bioRxiv preprint doi: https://doi.org/10.1101/2020.11.12.379636; this version posted November 12, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license. Loss of CDC50A function drives Aβ/p3 production via increased β/α-secretase processing of APP Marc D. Tambini & Luciano D’Adamio Department of Pharmacology, Physiology & Neuroscience New Jersey Medical School, Brain Health Institute, Jacqueline Krieger Klein Center in Alzheimer's Disease and Neurodegeneration Research, Rutgers, The State University of New Jersey, 185 South Orange Ave, Newark, NJ, 07103, USA. Correspondence to: [email protected], [email protected] 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.11.12.379636; this version posted November 12, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license. Abstract The Amyloid Precursor Protein (APP) undergoes extensive proteolytic processing to produce several biologically active metabolites which affect Alzheimer’s disease (AD) pathogenesis. Sequential cleavage of APP by β- and γ-secretases results in Aβ, while cleavage by α- and γ-secretases produces the smaller p3 peptide. Here we report that in cells in which the P4-ATPase flippase subunit CDC50A has been knocked out, large increases in the products of β- and α-secretase cleavage of APP (sAPPβ/βCTF and sAPPα/αCTF, respectively) and the downstream metabolites Aβ and p3 are seen.
    [Show full text]
  • Amyloid Peptide Has a Unique and Potentially Pathogenic Immunohistochemical Profile in Alzheimer's Disease Brain
    American Journal ofPathology, Vol. 149, No. 2, August 1996 Copyright t Amenican Societyfor Investigative Pathology p3 -Amyloid Peptide Has a Unique and Potentially Pathogenic Immunohistochemical Profile in Alzheimer's Disease Brain Linda S. Higgins,* Greer M. Murphy Jr.,t lism.13'14 The enzymology of 1-amyloid formation re- Lysia S. Forno,* Rosanne Catalano,* and mains unclear except that two proteolytic processing Barbara Cordell* steps are required to liberate 13-amyloid from the From Scios Nova Inc.,* Mountain View, California, and the backbone of 1-APP. The proteinase(s) that gener- Departments ofPsychiatry and Behavioral Sciencest and ates the amino terminus of the peptide is referred to Pathology,t Stanford University School ofMedicine, as 1-secretase and that producing the carboxy ter- Stanford, and the Veterans Administration Medical Center,f minus is referred to as y-secretase. Palo Alto, California Another 13-APP processing activity exists, a-secre- tase. This single processing event releases the bulk of the precursor from its membrane-bound state The presence of f-amyloid in brain tissue is such that it can be secreted into extracellular com- characteristic ofAlzbeimer's disease (AD). A nat- partments.1-17 The a-secretase cleavage occurs uraly occurring derivative ofthe -amyloidpep- near the transmembrane domain of 13-APP within the tide, p3, possesses aU of the structural determi- 13-amyloid domain. The primary a-secretase site of nants required for fibril assembly and proteolysis has been mapped between residues 16 neurotoxicity. p3-specific antibodies were used and 17 of the amyloid domain,18 although minor to examine the distribution of this peptide in cleavages have also been observed adjacent to this brain.
    [Show full text]
  • ELISA Analysis of Β-Secretase Cleavage of the Swedish Amyloid
    Journal of Neurochemistry, 2002, 80, 1019–1028 ELISA analysis of b-secretase cleavage of the Swedish amyloid precursor protein in the secretory and endocytic pathways Michelle L. Steinhilb,* R. Scott Turner and James R. Gautà *Institute of Gerontology and Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA Department of Neurology, University of Michigan Medical Center, Ann Arbor, Michigan, USA àVeterans Affairs Medical Center Geriatric Research, Education, and Clinical Center, Ann Arbor, Michigan, USA Abstract endocytic pathways. Using a dilysine retrieval motif to retain Limiting beta amyloid (Ab) production could become an APPsw in the ER, we discovered that less than 15% of the important therapeutic target in Alzheimer’s disease (AD). Ab is b-secretase cleavage was still detected. Experiments utilizing derived by the sequential cleavage of amyloid precursor pro- endocytosis-impaired mutants of APPsw revealed that little or tein (APP) by b- and c-secretases. A double missense no b-secretase cleavage of APPsw appears to take place mutation in APP found in a Swedish pedigree (APPsw) ele- through endocytosis. Surprisingly, deletion of the entire cyto- vates Ab40 and Ab42 production. Ab production and, there- plasmic tail increased both APPswb and Ab secretion, sug- fore, b-secretase cleavage of APPsw reportedly occur in the gesting that protein interactions with this region normally endoplasmic reticulum (ER), Golgi and endocytic compart- impede b-secretase cleavage. These results suggest that ments. However, the relative contribution of b-secretase APPsw is cleaved by b-secretase late in the secretory path- cleavage occurring in each compartment has not been way. determined.
    [Show full text]