Immunocytochemical Localization of Amyloid Protein AA in the “Dense Fibrillar Inclusions” of the Reticuloendothelical Cells

A1thought the mechanisms of amyloidogenesis have not been entirely clarified, proteolysis of the parent proteins may be one of the important steps in the amyloid fibril formation. Recently, we reported that "dense fibrillar inclusions" (DFI), which had the characteristics of lysosomes and contained organized fibrillar profiles as well, were observed in the reticuloendothelial cells in close association with the foci of new amyloid deposits. We considered the findings as evidence for the involvement of lysosomal system in amyloid fibril formation (l). In the present study, we attempted to determine the identity of the contents of the DFI by the use of antisera against the amyloid protein (AA) and an immuno-electron microscopic technique.Amyloidosis was induced in CBA/J mice by daily injections of casein (l). AA was isolated from amyloid-laden spleens by gel filtration and antibody to it was produced in rabbits (2). For immunocytochemistry, the unlabeled antibody enzyme method (3) was employed.

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Gold nanocolloid–protein interactions and their impact on β-sheet amyloid fibril formation

RSC Advances ◽

10.1039/c7ra11219j ◽

2018 ◽

Vol 8 (2) ◽

pp. 980-986 ◽

Cited By ~ 6

Author(s):

Heloise R. Barros ◽

Maria Kokkinopoulou ◽

Izabel C. Riegel-Vidotti ◽

Katharina Landfester ◽

Héloïse Thérien-Aubin

Keyword(s):

Protein Interactions ◽

Amyloid Fibril ◽

Interaction Mechanism ◽

Fibril Formation ◽

Amyloid Protein ◽

Degenerative Diseases ◽

Amyloid Fibril Formation ◽

Protein Fibrils ◽

Β Sheet

Formation of amyloid protein fibrils is associated with degenerative diseases. Here, the interaction mechanism between globular and fibrillar proteins with AuNPs were investigated in order to potentially control and reverse the fibrillation process.

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Sulfated polysaccharide ascophyllan prevents amyloid fibril formation of human insulin and inhibits amyloid-induced hemolysis and cytotoxicity in PC12 cells

Bioscience Biotechnology and Biochemistry ◽

10.1093/bbb/zbab163 ◽

2021 ◽

Author(s):

Yan Liang ◽

Mikinori Ueno ◽

Shijiao Zha ◽

Takasi Okimura ◽

Zedong Jiang ◽

...

Keyword(s):

Pc12 Cells ◽

Human Insulin ◽

Amyloid Fibril ◽

Gel Filtration ◽

Sulfated Polysaccharide ◽

Fibril Formation ◽

Sulfated Polysaccharides ◽

Structure Transition ◽

Amyloid Fibril Formation ◽

Α Helix

Abstract We found that ascophyllan significantly inhibited the fibrillation of human insulin, and was the most effective among the sulfated polysaccharides tested. Gel-filtration analysis suggested that ascophyllan was capable of forming a complex with insulin through a weak interaction. Secondary structure transition from native α-helix to β-sheet predominant structure of insulin under the fibrillation conditions was suppressed in the presence of ascophyllan. Interestingly, ascophyllan attenuated insulin fibrils-induced hemolysis of human erythrocytes. Moreover ascophyllan attenuated insulin amyloid induced cytotoxicity on rat pheochromocytoma PC12 cells and reduced the level of intracellular reactive oxygen species (ROS). This is the first report indicating that a sulfated polysaccharide, ascophyllan can suppress the insulin amyloid fibril formation and inhibit the fibril-induced detrimental bioactivities.

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Abstract 312: Amyloids of Oxidized Apolipoprotein A-I Induce Amyloid Fibril Formation in Intact Apolipoprotein A-I

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.35.suppl_1.312 ◽

2015 ◽

Vol 35 (suppl_1) ◽

Author(s):

Gary K Chan ◽

Andrzej Witkowski ◽

Giorgio Cavigiolio

Keyword(s):

Amyloid Fibrils ◽

Amyloid Fibril ◽

Fibril Formation ◽

Atherosclerotic Plaques ◽

Amyloid Formation ◽

Atherosclerotic Lesions ◽

Apolipoprotein A ◽

Amyloid Deposits ◽

Amyloid Fibril Formation ◽

Tht Fluorescence

Background: Amyloid deposition in atherosclerotic plaques increases with aging. Although a correlation between arterial amyloid deposits and cardiovascular events is yet to be established, the high incidence of amyloids associated with aortic intima and with atherosclerotic lesions indicates that amyloid deposits may contribute to atherosclerosis progression. Remarkably, apolipoprotein A-I (apoA-I) is the main component of these amyloids. We previously demonstrated that oxidation of apoA-I methionines by myeloperoxidase, at a concentration similar to that produced by activated macrophages in atherosclerotic lesions, promotes apoA-I amyloid fibril formation. Furthermore, recent studies revealed a hundred-fold increase in the amount of lipid-free apoA-I in atherosclerotic arteries compared to normal arteries. Notably, this apoA-I is heavily oxidized. Thus in the atherosclerotic plaques, high concentration of lipid-free apoA-I and an oxidative milieu are favorable conditions for apoA-I amyloid formation. Hypothesis: We tested the hypothesis that amyloid fibrils constituted of oxidized apoA-I can transfer the dysfunctional phenotype to intact apoA-I. Methods: Pre-formed amyloid fibrils constituted of oxidized apoA-I were incubated with a 10-fold excess of intact apoA-I at 37 °C, pH 6.0, with continuous vortexing. Kinetics of amyloid fibril formation by the pool of intact apoA-I were derived by measuring Thioflavin-T (ThT) fluorescence over a 6-day period. Results: After a lag-phase of 24-48 h, fibril formation proceeded with typical sigmoidal kinetics and reached plateau levels after about 6 days. In control samples, in which intact apoA-I was incubated in the absence of pre-formed fibrils, no significant changes in ThT fluorescence were detected for the same time course. Conclusions: Oxidized apoA-I amyloid fibrils can catalyze the aggregation of a large excess of intact protein. This observation bears important pathophysiological implications. In vivo , a small amount of amyloid fibrils could be produced by oxidized apoA-I in specific microenvironments of the atheroma; when transferred to the surrounding tissues, these amyloid seeds could induce extended amyloid formation in the large available pool of lipid-free apoA-I.

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