scholarly journals AA amyloid fibrils from diseased tissue are structurally different from in vitro formed SAA fibrils

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Akanksha Bansal ◽  
Matthias Schmidt ◽  
Matthies Rennegarbe ◽  
Christian Haupt ◽  
Falk Liberta ◽  
...  
Keyword(s):  
Protein Misfolding ◽  
Serum Amyloid A ◽  
Amyloid Fibrils ◽  
Ex Vivo ◽  
Surrounding Tissue ◽  
Amyloid A ◽  
Cryo Electron Microscopy ◽  
Β Sheet ◽  
Misfolding Disease

AbstractSystemic AA amyloidosis is a world-wide occurring protein misfolding disease of humans and animals. It arises from the formation of amyloid fibrils from serum amyloid A (SAA) protein. Using cryo electron microscopy we here show that amyloid fibrils which were purified from AA amyloidotic mice are structurally different from fibrils formed from recombinant SAA protein in vitro. Ex vivo amyloid fibrils consist of fibril proteins that contain more residues within their ordered parts and possess a higher β-sheet content than in vitro fibril proteins. They are also more resistant to proteolysis than their in vitro formed counterparts. These data suggest that pathogenic amyloid fibrils may originate from proteolytic selection, allowing specific fibril morphologies to proliferate and to cause damage to the surrounding tissue.

Methods to study the structure of misfolded protein states in systemic amyloidosis

2021 ◽  
Vol 49 (2) ◽  
pp. 977-985
Author(s):  
Marcus Fändrich ◽  
Matthias Schmidt
Keyword(s):  
Protein Misfolding ◽  
Amyloid Fibrils ◽  
Ex Vivo ◽  
Systemic Amyloidosis ◽  
Structural Basis ◽  
Amyloid A ◽  
Serum Amyloid A Protein ◽  
Proteolytic Stability

Systemic amyloidosis is defined as a protein misfolding disease in which the amyloid is not necessarily deposited within the same organ that produces the fibril precursor protein. There are different types of systemic amyloidosis, depending on the protein constructing the fibrils. This review will focus on recent advances made in the understanding of the structural basis of three major forms of systemic amyloidosis: systemic AA, AL and ATTR amyloidosis. The three diseases arise from the misfolding of serum amyloid A protein, immunoglobulin light chains or transthyretin. The presented advances in understanding were enabled by recent progress in the methodology available to study amyloid structures and protein misfolding, in particular concerning cryo-electron microscopy (cryo-EM) and nuclear magnetic resonance (NMR) spectroscopy. An important observation made with these techniques is that the structures of previously described in vitro formed amyloid fibrils did not correlate with the structures of amyloid fibrils extracted from diseased tissue, and that in vitro fibrils were typically more protease sensitive. It is thus possible that ex vivo fibrils were selected in vivo by their proteolytic stability.

scholarly journals Cryo-EM demonstrates the in vitro proliferation of an ex vivo amyloid fibril morphology by seeding

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Thomas Heerde ◽  
Matthies Rennegarbe ◽  
Alexander Biedermann ◽  
Dilan Savran ◽  
Peter B. Pfeiffer ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Ex Vivo ◽  
Proteinase K ◽  
Seed Structure ◽  
In Vitro Proliferation ◽  
Amyloid A ◽  
Fibril Structure ◽  
Proteolytic Stability ◽  
Fibril Morphology

AbstractSeveral studies showed that seeding of solutions of monomeric fibril proteins with ex vivo amyloid fibrils accelerated the kinetics of fibril formation in vitro but did not necessarily replicate the seed structure. In this research we use cryo-electron microscopy and other methods to analyze the ability of serum amyloid A (SAA)1.1-derived amyloid fibrils, purified from systemic AA amyloidosis tissue, to seed solutions of recombinant SAA1.1 protein. We show that 98% of the seeded fibrils remodel the full fibril structure of the main ex vivo fibril morphology, which we used for seeding, while they are notably different from unseeded in vitro fibrils. The seeded fibrils show a similar proteinase K resistance as ex vivo fibrils and are substantially more stable to proteolytic digestion than unseeded in vitro fibrils. Our data support the view that the fibril morphology contributes to determining proteolytic stability and that pathogenic amyloid fibrils arise from proteolytic selection.

scholarly journals Ex Vivo and In Vitro Effect of Serum Amyloid A in the Induction of Macrophage M2 Markers and Efferocytosis of Apoptotic Neutrophils

2015 ◽  
Vol 194 (10) ◽  
pp. 4891-4900 ◽  
Author(s):  
Lei Sun ◽  
Huibin Zhou ◽  
Ziyan Zhu ◽  
Qian Yan ◽  
Lili Wang ◽  
...  
Keyword(s):  
Serum Amyloid A ◽  
Ex Vivo ◽  
Serum Amyloid ◽  
Amyloid A ◽  
Vitro Effect

scholarly journals Recent Insights into the Pathogenesis of Type AA Amyloidosis

2011 ◽  
Vol 11 ◽  
pp. 641-650 ◽  
Author(s):  
J. C. H. van der Hilst
Keyword(s):  
Amino Acids ◽  
Amyloid Fibrils ◽  
Rare Event ◽  
Helical Structure ◽  
Amyloid A ◽  
Acid Protein ◽  
Life Threatening ◽  
Shock Proteins ◽  
Β Sheet

The amyloidoses are a group of life-threatening diseases in which fibrils made of misfolded proteins are deposited in organs and tissues. The fibrils are stable, insoluble aggregates of precursor proteins that have adopted an antiparallel β-sheet structure. In type AA, or reactive, amyloidosis, the precursor protein of the fibrils is serum amyloid A (SAA). SAA is a 104-amino-acid protein that is produced in the liver in response to proinflammatory cytokines. Although the protein that is produced by the liver contains 104 amino acids, only the N-terminal 66–76 amino acids are found in amyloid fibrils. Furthermore, SAA has been shown to have an α-helical structure primarily. Thus, for SAA to be incorporated into an amyloid fibril, two processes have to occur: C-terminal cleavage and conversion into a β-sheet. Only a minority of patients with elevated SAA levels develop amyloidosis. Factors that contribute to the risk of amyloidosis include the duration and degree of SAA elevation, polymorphisms in SAA, and the type of autoinflammatory syndrome. In the Hyper-IgD syndrome, amyloidosis is less prevalent than in the other autoinflammatory diseases.In vitrowork has shown that the isoprenoid pathway influences amyloidogenesis by farnesylated proteins. Although many proteins contain domains that have a potential for self-aggregation, amyloidosis is only a very rare event. Heat shock proteins (HSPs) are chaperones that assist other proteins to attain, maintain, and regain a functional conformation. In this review, recent insights into the pathogenesis of amyloidosis are discussed, in addition to a new hypothesis for a role of HSPs in the pathogenesis of type AA.

scholarly journals Protease Resistance of ex vivo Amyloid Fibrils implies the proteolytic Selection of disease-associated Fibril Morphologies

2021 ◽  
Author(s):  
Jonathan Schoenfelder ◽  
Peter Benedikt Pfeiffer ◽  
Tejaswini Pradhan ◽  
Johan Bijzet ◽  
Bouke P.C. Hazenberg ◽  
...  
Keyword(s):  
Amyloid Fibrils ◽  
Ex Vivo ◽  
Amino Acid Sequences ◽  
The Body ◽  
Amyloid A ◽  
Chain Analysis ◽  
Polypeptide Chains ◽  
Amyloid Diseases ◽  
Selection Of

Several studies recently showed that ex vivo fibrils from patient or animal tissue were structurally different from in vitro formed fibrils from the same polypeptide chain. Analysis of serum amyloid A (SAA) and Aβ-derived amyloid fibrils additionally revealed that ex vivo fibrils were more protease stable than in vitro fibrils. These observations gave rise to the proteolytic selection hypothesis that suggested that disease-associated amyloid fibrils were selected inside the body by their ability to resist endogenous clearance mechanisms. We here show, for more than twenty different fibril samples, that ex vivo fibrils are more protease stable than in vitro fibrils. These data support the idea of a proteolytic selection of pathogenic amyloid fibril morphologies and help to explain why only few amino acid sequences lead to amyloid diseases, although many, if not all, polypeptide chains can form amyloid fibrils in vitro.

scholarly journals Bifunctional amyloid-reactive peptide promotes binding of antibody 11-1F4 to diverse amyloid types and enhances therapeutic efficacy

2018 ◽  
Vol 115 (46) ◽  
pp. E10839-E10848 ◽  
Author(s):  
Jonathan S. Wall ◽  
Angela D. Williams ◽  
James S. Foster ◽  
Tina Richey ◽  
Alan Stuckey ◽  
...  
Keyword(s):  
Serum Amyloid A ◽  
Amyloid Fibrils ◽  
Serum Amyloid ◽  
Al Amyloidosis ◽  
Peptide Epitope ◽  
Amyloid A ◽  
Affinity Peptide ◽  
The Many

Amyloidosis is a malignant pathology associated with the formation of proteinaceous amyloid fibrils that deposit in organs and tissues, leading to dysfunction and severe morbidity. More than 25 proteins have been identified as components of amyloid, but the most common form of systemic amyloidosis is associated with the deposition of amyloid composed of Ig light chains (AL). Clinical management of amyloidosis focuses on reducing synthesis of the amyloid precursor protein. However, recently, passive immunotherapy using amyloid fibril-reactive antibodies, such as 11-1F4, to remove amyloid from organs has been shown to be effective at restoring organ function in patients with AL amyloidosis. However, 11-1F4 does not bind amyloid in all AL patients, as evidenced by PET/CT imaging, nor does it efficiently bind the many other forms of amyloid. To enhance the reactivity and expand the utility of the 11-1F4 mAb as an amyloid immunotherapeutic, we have developed a pretargeting “peptope” comprising a multiamyloid-reactive peptide, p5+14, fused to a high-affinity peptide epitope recognized by 11-1F4. The peptope, known as p66, bound the 11-1F4 mAb in vitro with subnanomolar efficiency, exhibited multiamyloid reactivity in vitro and, using tissue biodistribution and SPECT imaging, colocalized with amyloid deposits in a mouse model of systemic serum amyloid A amyloidosis. Pretreatment with the peptope induced 11-1F4 mAb accumulation in serum amyloid A deposits in vivo and enhanced 11-1F4–mediated dissolution of a human AL amyloid extract implanted in mice.

scholarly journals Pancreatic beta-cell granule peptides form heteromolecular complexes which inhibit islet amyloid polypeptide fibril formation

2004 ◽  
Vol 377 (3) ◽  
pp. 709-716 ◽  
Author(s):  
Emma T. A. S. JAIKARAN ◽  
Melanie R. NILSSON ◽  
Anne CLARK
Keyword(s):  
Type 2 Diabetes ◽  
Amyloid Fibrils ◽  
Secretory Granules ◽  
Pancreatic Beta Cell ◽  
Islet Amyloid Polypeptide ◽  
Fibril Formation ◽  
Islet Amyloid ◽  
Β Sheet

Islet amyloid polypeptide (IAPP), or ‘amylin’, is co-stored with insulin in secretory granules of pancreatic islet β-cells. In Type 2 diabetes, IAPP converts into a β-sheet conformation and oligomerizes to form amyloid fibrils and islet deposits. Granule components, including insulin, inhibit spontaneous IAPP fibril formation in vitro. To determine the mechanism of this inhibition, molecular interactions of insulin with human IAPP (hIAPP), rat IAPP (rIAPP) and other peptides were examined using surface plasmon resonance (BIAcore), CD and transmission electron microscopy (EM). hIAPP and rIAPP complexed with insulin, and this reaction was concentration-dependent. rIAPP and insulin, but not pro-insulin, bound to hIAPP. Insulin with a truncated B-chain, to prevent dimerization, also bound hIAPP. In the presence of insulin, hIAPP did not spontaneously develop β-sheet secondary structure or form fibrils. Insulin interacted with pre-formed IAPP fibrils in a regular repeating pattern, as demonstrated by immunoEM, suggesting that the binding sites for insulin remain exposed in hIAPP fibrils. Since rIAPP and hIAPP form complexes with insulin (and each other), this could explain the lack of amyloid fibrils in transgenic mice expressing hIAPP. It is likely that IAPP fibrillogenesis is inhibited in secretory granules (where the hIAPP concentration is in the millimolar range) by heteromolecular complex formation with insulin. Alterations in the proportions of insulin and IAPP in granules could disrupt the stability of the peptide. The increase in the proportion of unprocessed pro-insulin produced in Type 2 diabetes could be a major factor in destabilization of hIAPP and induction of fibril formation.

Abstract 110: The Separation of Serum Amyloid A from HDL is Mediated by Heparan Sulfate Through Histidine Dependent Interactions: HDL Function is Enhanced but Amyloid-Fibrils may be the “Price to Pay”¼

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
John B Ancsin ◽  
Kim Munro ◽  
Shui-Pang Tam ◽  
Michael H Davidson
Keyword(s):  
Heparan Sulfate ◽  
Serum Amyloid A ◽  
Amyloid Fibrils ◽  
3D Structure ◽  
Serum Amyloid ◽  
Acidic Ph ◽  
Heparin Binding ◽  
Additional Time ◽  
Amyloid A ◽  
Hdl Function

Serum amyloid A (SAA) is an acute-phase protein that circulates bound to high density lipoprotein (HDL) and can influence HDL function as part of a poorly understood defense re-sponse to tissue trauma or infection. We have previously demonstrated that under mildly acidic pH the glycosaminoglycans, heparan sulfate (HS) and heparin can interact with HDL-SAA and cause SAA to dissociate from HDL. This remodeling improves HDL functionality but also predisposes SAA to form AA-amyloid fibrils. In this study we explore some potential pathophysiological conditions in vitro that could influence this HS/HDL-SAA remodeling process and the fate of SAA in vivo. SAA’s binding affinity for heparin was found to be enhanced by acidic pH and low concentrations of urea. The heparin dependent remodeling of HDL-SAA was promoted by the partial denaturation of HDL-SAA. Moreover, HDL-SAA remodeling was observed to follow a strict SAA:heparin stoichiometry and could be partially inhibited with a short heparin oligosaccharide of 8-sugar units. Evidence is also presented that once dissociated from HDL, SAA requires additional time to organize into Triton x-100 resistant amyloid-like structures. Circular dichroism spectroscopic analysis and in silico modeling of SAA’s ionizable residues highlights the importance of the histidine-36 within a highly conserved, pH-sensitive HS-binding site (HSBS-pH). A peptide containing the HSBS-pH sequence was demonstrated to have AA-amyloid seeding activity in a cell culture system. The recent determination of the 3D structure for human SAA1.1 has allowed the opportunity to re-assess and validate the HS/heparin binding sequences that had previously been identified biochemically with short synthetic peptides. We postulate that the dissociation of SAA from HDL takes place during the retro-endocytosis of HDL-SAA and is an important aspect of SAA function not previously appreciated.

Abstract 226: Serum Amyloid A Isoforms and the Capacity to Mediate Cholesterol Efflux

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Hussein Yassine ◽  
Olgica Trenchevska ◽  
Chad Borges ◽  
Dobrin Nedelkov ◽  
Randall W Nelson ◽  
...  
Keyword(s):  
Cholesterol Efflux ◽  
Serum Amyloid A ◽  
Hdl Cholesterol ◽  
Acute Phase Reactant ◽  
Serum Amyloid ◽  
Amyloid A ◽  
Cholesterol Levels ◽  
Acute Phase Reactant Protein

Serum Amyloid A (SAA) is an acute phase reactant protein that exists in multiple isoforms, can form HDL, and participates in cholesterol efflux. In vitro studies suggest that the SAA 2.1 isoform has an increased capacity to mediate cholesterol efflux compared to the other isoforms. We examined SAA isoforms using a novel mass spectrometric immunoassay (MSIA) and HDL’s cholesterol efflux capacity (via ABCA-1 and SR-BI) in samples from 59 subjects with (n=33) and without type 2 diabetes (n=26). SAA 1.1 levels were detectable in 58, SAA 2.1 in 14 and SAA 2.2 in 36 of the 59 subjects. SAA 2.1 levels significantly correlated with SR-BI cholesterol efflux (r=0.71, p=0.01, n=14), but not ABCA-1 mediated efflux (r=0.1, P=0.1). This correlation was not explained by changes in HDL phospholipids, Apo A-I or HDL cholesterol levels. In contrast, SAA 2.2 or 1.1 levels did not correlate with changes in SR-BI or ABCA-1 mediated efflux. Although the SAA 2.1 isoform is less frequently detected in plasma, our data confirm that it is closely linked with HDL mediated cholesterol efflux, particularly that is SR-BI mediated.

A case report of biochemistry and serum amyloid A in a moribund free-ranging Baltic herring gull (Larus argentatus) with necrotic wing fracture

2021 ◽  
Vol 1 (2) ◽  
pp. 56-60
Author(s):  
Svend-Erik Garbus ◽  
Pelle Garbus ◽  
Thomas B. Jessen ◽  
Astrid B. Kjaergaard ◽  
Christian Sonne
Keyword(s):  
Serum Amyloid A ◽  
Secondary Infection ◽  
Serum Amyloid ◽  
Surrounding Tissue ◽  
Larus Argentatus ◽  
Herring Gull ◽  
Amyloid A ◽  
Elevated Creatinine ◽  
The Right ◽  
Free Ranging

An adult herring gull (Larus argentatus) found lethargic and moribund showed an open fracture of the right radius and ulna with necrosis of the surrounding tissue. Hematologic testing and plasma biochemical analysis revealed elevated creatinine kinase consistent with traumatic muscle damage in addition to hyperuricemia, hyperkalaemia, and hyperphosphatemia consistent with renal insufficiency. Increase in the acute phase protein Serum Amyloid A indicate a high degree of inflammation supported by leucocytosis, heterophilia, and hypoglycaemia pointing towards septicaemia. This case provides knowledge about Serum Amyloid A in gulls, and how bone fracture and secondary infection may affect gull blood haematology and biochemistry.

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