The cerebrospinal-fluid soluble form of Alzheimer's amyloid β is complexed to SP-40,40 (apolipoprotein J), an inhibitor of the complement membrane-attack complex

The amyloid fibrils deposited in Alzheimer's neuritic plaque cores and cerebral blood vessels are mainly composed of aggregated forms of a unique peptide, 39-42 amino acids long, named amyloid beta (A beta). A similar, although soluble, A beta (‘sA beta’) has been identified in cerebrospinal fluid, plasma and cell supernatants, indicating that it is normally produced by proteolytic processing of its precursor protein, amyloid precursor protein (APP). Using direct binding experiments we have isolated and characterized an 80 kDa circulating protein that specifically interacts with a synthetic peptide identical with A beta. The protein was unmistakably identified as SP-40,40 or ApoJ, a cytolytic inhibitor and lipid carrier, by means of amino acid sequence and immunoreactivity with specific antibodies. Immunoprecipitation with anti-SP-40,40 retrieved soluble A beta from cerebrospinal fluid, indicating that the interaction occurs in vivo.

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The Amyloid Fibril-Forming β-Sheet Regions of Amyloid β and α-Synuclein Preferentially Interact with the Molecular Chaperone 14-3-3ζ

Molecules ◽

10.3390/molecules26206120 ◽

2021 ◽

Vol 26 (20) ◽

pp. 6120

Author(s):

Danielle M. Williams ◽

David C. Thorn ◽

Christopher M. Dobson ◽

Sarah Meehan ◽

Sophie E. Jackson ◽

...

Keyword(s):

Nmr Spectroscopy ◽

Molecular Chaperones ◽

Protein Unfolding ◽

Amyloid Fibrils ◽

Amyloid Β ◽

Parkinson’S Diseases ◽

Amino Acid Form ◽

Shock Proteins

14-3-3 proteins are abundant, intramolecular proteins that play a pivotal role in cellular signal transduction by interacting with phosphorylated ligands. In addition, they are molecular chaperones that prevent protein unfolding and aggregation under cellular stress conditions in a similar manner to the unrelated small heat-shock proteins. In vivo, amyloid β (Aβ) and α-synuclein (α-syn) form amyloid fibrils in Alzheimer’s and Parkinson’s diseases, respectively, a process that is intimately linked to the diseases’ progression. The 14-3-3ζ isoform potently inhibited in vitro fibril formation of the 40-amino acid form of Aβ (Aβ40) but had little effect on α-syn aggregation. Solution-phase NMR spectroscopy of 15N-labeled Aβ40 and A53T α-syn determined that unlabeled 14-3-3ζ interacted preferentially with hydrophobic regions of Aβ40 (L11-H21 and G29-V40) and α-syn (V3-K10 and V40-K60). In both proteins, these regions adopt β-strands within the core of the amyloid fibrils prepared in vitro as well as those isolated from the inclusions of diseased individuals. The interaction with 14-3-3ζ is transient and occurs at the early stages of the fibrillar aggregation pathway to maintain the native, monomeric, and unfolded structure of Aβ40 and α-syn. The N-terminal regions of α-syn interacting with 14-3-3ζ correspond with those that interact with other molecular chaperones as monitored by in-cell NMR spectroscopy.

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Cerebrospinal fluid biomarkers of β-amyloid metabolism in multiple sclerosis

Multiple Sclerosis Journal ◽

10.1177/1352458512460603 ◽

2012 ◽

Vol 19 (5) ◽

pp. 543-552 ◽

Cited By ~ 32

Author(s):

Kristin Augutis ◽

Markus Axelsson ◽

Erik Portelius ◽

Gunnar Brinkmalm ◽

Ulf Andreasson ◽

...

Keyword(s):

Multiple Sclerosis ◽

Cerebrospinal Fluid ◽

Inflammatory Diseases ◽

Amyloid Β ◽

Csf Biomarkers ◽

Aβ Peptide ◽

Aβ Peptides ◽

App Metabolism ◽

Disease Modifying

Background: Amyloid precursor protein (APP) and amyloid β (Aβ) peptides are intensely studied in neuroscience and their cerebrospinal fluid (CSF) measurements may be used to track the metabolic pathways of APP in vivo. Reduced CSF levels of Aβ and soluble APP (sAPP) fragments are reported in inflammatory diseases, including multiple sclerosis (MS); but in MS, the precise pathway of APP metabolism and whether it can be affected by disease-modifying treatments remains unclear. Objective: To characterize the CSF biomarkers of APP degradation in MS, including the effects of disease-modifying therapy. Methods: CSF samples from 87 MS patients (54 relapsing–remitting (RR) MS; 33 secondary progressive (SP) MS and 28 controls were analyzed for sAPP and Aβ peptides by immunoassays, plus a subset of samples was analyzed by immunoprecipitation and mass spectrometry (IP-MS). Patients treated with natalizumab or mitoxantrone were examined at baseline, and after 1–2 years of treatment. Results: CSF sAPP and Aβ peptide levels were reduced in MS patients; but they increased again towards normal, after natalizumab treatment. A multivariate model of IP-MS-measured Aβ species separated the SPMS patients from controls, with RRMS patients having intermediate levels. Conclusions: We confirmed and extended our previous observations of altered CSF sAPP and Aβ peptide levels in MS patients. We found that natalizumab therapy may be able to counteract the altered APP metabolism in MS. The CSF Aβ isoform distribution was found to be distinct in SPMS patients, as compared to the controls.

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In Vivo Microdialysis in Mice Captures Changes in Alzheimer’s Disease Cerebrospinal Fluid Biomarkers Consistent with Developing Pathology

Journal of Alzheimer s Disease ◽

10.3233/jad-210715 ◽

2021 ◽

pp. 1-14

Author(s):

Christiana Bjorkli ◽

Claire Louet ◽

Trude Helen Flo ◽

Mary Hemler ◽

Axel Sandvig ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Cerebrospinal Fluid ◽

Mouse Model ◽

Amyloid Β ◽

Csf Biomarkers ◽

Intracerebral Microdialysis ◽

Preclinical Models ◽

The Brain

Background: Preclinical models of Alzheimer’s disease (AD) can provide valuable insights into the onset and progression of the disease, such as changes in concentrations of amyloid-β (Aβ) and tau in cerebrospinal fluid (CSF). However, such models are currently underutilized due to limited advancement in techniques that allow for longitudinal CSF monitoring. Objective: An elegant way to understand the biochemical environment in the diseased brain is intracerebral microdialysis, a method that has until now been limited to short-term observations, or snapshots, of the brain microenvironment. Here we draw upon patient-based findings to characterize CSF biomarkers in a commonly used preclinical mouse model for AD. Methods: Our modified push-pull microdialysis method was first validated ex vivo with human CSF samples, and then in vivo in an AD mouse model, permitting assessment of dynamic changes of CSF Aβ and tau and allowing for better translational understanding of CSF biomarkers. Results: We demonstrate that CSF biomarker changes in preclinical models capture what is observed in the brain; with a decrease in CSF Aβ observed when plaques are deposited, and an increase in CSF tau once tau pathology is present in the brain parenchyma. We found that a high molecular weight cut-off membrane allowed for simultaneous sampling of Aβ and tau, comparable to CSF collection by lumbar puncture in patients. Conclusion: Our approach can further advance AD and other neurodegenerative research by following evolving neuropathology along the disease cascade via consecutive sampling from the same animal and can additionally be used to administer pharmaceutical compounds and assess their efficacy (Bjorkli, unpublished data).

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An online nano-LC-ESI-FTICR-MS method for comprehensive characterization of endogenous fragments from amyloid β and amyloid precursor protein in human and cat cerebrospinal fluid

Journal of Mass Spectrometry ◽

10.1002/jms.2987 ◽

2012 ◽

Vol 47 (5) ◽

pp. 591-603 ◽

Cited By ~ 55

Author(s):

Gunnar Brinkmalm ◽

Erik Portelius ◽

Annika Öhrfelt ◽

Niklas Mattsson ◽

Rita Persson ◽

...

Keyword(s):

Cerebrospinal Fluid ◽

Amyloid Precursor Protein ◽

Amyloid Β ◽

Precursor Protein ◽

Fticr Ms ◽

Comprehensive Characterization

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A Conserved Biogenesis Pathway for Nucleoporins: Proteolytic Processing of a 186-Kilodalton Precursor Generates Nup98 and the Novel Nucleoporin, Nup96

The Journal of Cell Biology ◽

10.1083/jcb.144.6.1097 ◽

1999 ◽

Vol 144 (6) ◽

pp. 1097-1112 ◽

Cited By ~ 169

Author(s):

Beatriz M.A. Fontoura ◽

Günter Blobel ◽

Michael J. Matunis

Keyword(s):

Proteolytic Cleavage ◽

Proteolytic Processing ◽

Precursor Protein ◽

Nuclear Pore ◽

Biochemical Fractionation ◽

Alternatively Spliced ◽

Functional Analyses ◽

Related Proteins

The mammalian nuclear pore complex (NPC) is comprised of ∼50 unique proteins, collectively known as nucleoporins. Through fractionation of rat liver nuclei, we have isolated >30 potentially novel nucleoporins and have begun a systematic characterization of these proteins. Here, we present the characterization of Nup96, a novel nucleoporin with a predicted molecular mass of 96 kD. Nup96 is generated through an unusual biogenesis pathway that involves synthesis of a 186-kD precursor protein. Proteolytic cleavage of the precursor yields two nucleoporins: Nup98, a previously characterized GLFG-repeat containing nucleoporin, and Nup96. Mutational and functional analyses demonstrate that both the Nup98-Nup96 precursor and the previously characterized Nup98 (synthesized independently from an alternatively spliced mRNA) are proteolytically cleaved in vivo. This biogenesis pathway for Nup98 and Nup96 is evolutionarily conserved, as the putative Saccharomyces cerevisiae homologues, N-Nup145p and C-Nup145p, are also produced through proteolytic cleavage of a precursor protein. Using immunoelectron microscopy, Nup96 was localized to the nucleoplasmic side of the NPC, at or near the nucleoplasmic basket. The correct targeting of both Nup96 and Nup98 to the nucleoplasmic side of the NPC was found to be dependent on proteolytic cleavage, suggesting that the cleavage process may regulate NPC assembly. Finally, by biochemical fractionation, a complex containing Nup96, Nup107, and at least two Sec13- related proteins was identified, revealing that a major sub-complex of the NPC is conserved between yeast and mammals.

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Deposition of amyloid fibrils promotes cell-surface accumulation of amyloid β precursor protein

Neurobiology of Disease ◽

10.1016/j.nbd.2004.04.015 ◽

2004 ◽

Vol 16 (3) ◽

pp. 617-629 ◽

Cited By ~ 20

Author(s):

Lorena Heredia ◽

Rong Lin ◽

Francisco Solá Vigo ◽

Gabriela Kedikian ◽

Jorge Busciglio ◽

...

Keyword(s):

Cell Surface ◽

Amyloid Fibrils ◽

Amyloid Β ◽

Precursor Protein

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Contribution of GABAergic interneurons to amyloid-β plaque pathology in an APP knock-in mouse model

Molecular Neurodegeneration ◽

10.1186/s13024-019-0356-y ◽

2020 ◽

Vol 15 (1) ◽

Cited By ~ 5

Author(s):

Heather C. Rice ◽

Gabriele Marcassa ◽

Iordana Chrysidou ◽

Katrien Horré ◽

Tracy L. Young-Pearse ◽

...

Keyword(s):

Mouse Model ◽

Integration Site ◽

Amyloid Β ◽

Cell Types ◽

Proteolytic Processing ◽

Gabaergic Interneurons ◽

Amyloid Burden ◽

Plaque Pathology ◽

Plaque Load

AbstractThe amyloid-β (Aβ) peptide, the primary constituent of amyloid plaques found in Alzheimer’s disease (AD) brains, is derived from sequential proteolytic processing of the Amyloid Precursor Protein (APP). However, the contribution of different cell types to Aβ deposition has not yet been examined in an in vivo, non-overexpression system. Here, we show that endogenous APP is highly expressed in a heterogeneous subset of GABAergic interneurons throughout various laminae of the hippocampus, suggesting that these cells may have a profound contribution to AD plaque pathology. We then characterized the laminar distribution of amyloid burden in the hippocampus of an APP knock-in mouse model of AD. To examine the contribution of GABAergic interneurons to plaque pathology, we blocked Aβ production specifically in these cells using a cell type-specific knock-out of BACE1. We found that during early stages of plaque deposition, interneurons contribute to approximately 30% of the total plaque load in the hippocampus. The greatest contribution to plaque load (75%) occurs in the stratum pyramidale of CA1, where plaques in human AD cases are most prevalent and where pyramidal cell bodies and synaptic boutons from perisomatic-targeting interneurons are located. These findings reveal a crucial role of GABAergic interneurons in the pathology of AD. Our study also highlights the necessity of using APP knock-in models to correctly evaluate the cellular contribution to amyloid burden since APP overexpressing transgenic models drive expression in cell types according to the promoter and integration site and not according to physiologically relevant expression mechanisms.

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Kinetic Transition in Amyloid Assembly as a Screening Assay for Oligomer-Selective Dyes

Biomolecules ◽

10.3390/biom9100539 ◽

2019 ◽

Vol 9 (10) ◽

pp. 539 ◽

Cited By ~ 1

Author(s):

Jeremy Barton ◽

D. Sebastian Arias ◽

Chamani Niyangoda ◽

Gustavo Borjas ◽

Nathan Le ◽

...

Keyword(s):

Crystal Violet ◽

Amyloid Fibrils ◽

Amyloid Β ◽

Fibril Formation ◽

Thioflavin T ◽

Screening Assay ◽

Kinetic Transition ◽

Amyloid Assembly

Assembly of amyloid fibrils and small globular oligomers is associated with a significant number of human disorders that include Alzheimer’s disease, senile systemic amyloidosis, and type II diabetes. Recent findings implicate small amyloid oligomers as the dominant aggregate species mediating the toxic effects in these disorders. However, validation of this hypothesis has been hampered by the dearth of experimental techniques to detect, quantify, and discriminate oligomeric intermediates from late-stage fibrils, in vitro and in vivo. We have shown that the onset of significant oligomer formation is associated with a transition in thioflavin T kinetics from sigmoidal to biphasic kinetics. Here we showed that this transition can be exploited for screening fluorophores for preferential responses to oligomer over fibril formation. This assay identified crystal violet as a strongly selective oligomer-indicator dye for lysozyme. Simultaneous recordings of amyloid kinetics with thioflavin T and crystal violet enabled us to separate the combined signals into their underlying oligomeric and fibrillar components. We provided further evidence that this screening assay could be extended to amyloid-β peptides under physiological conditions. Identification of oligomer-selective dyes not only holds the promise of biomedical applications but provides new approaches for unraveling the mechanisms underlying oligomer versus fibril formation in amyloid assembly.

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