Amyloid-enhancing factor mediates amyloid formation on fibroblasts via a nidus/template mechanism

Nadine Magy, Juris J. Liepnieks, Merrill Benson, Barbara Kluve-Beckerman

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Objective. To determine the mechanism by which amyloid-enhancing factor (AEF) promotes amyloid deposition, and to test whether AEF seeds deposition of serum amyloid A (SAA) and facilitates conversion to beta-sheet structure. Methods. Fibroblasts were cultured with mouse recombinant SAA1.1 and AEF, SAA1.1, or AEF. AEF was prepared as a glycerol extract of spleen from amyloidotic mice. Amyloid was identified by staining with Congo red and examining for green birefringence under polarized light. SAA was localized immunohisto-chemically. Texas Red-labeled SAA was visualized in living cultures by fluorescence confocal microscopy. AEF was characterized by Western blot analysis using anti-SAA antiserum and N-terminal sequence analysis. Subunits comprising amyloid in fibroblast cultures were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results. Amyloid was produced in fibroblast cultures by an AEF-dependent mechanism. AEF, added to culture medium as insoluble protein precipitates, adhered to fibroblast monolayers. SAA bound preferentially to the adherent precipitates. Coincident with SAA binding, precipitates developed an affinity for Congo red. Over time, as more SAA was added, networks of Congo red-positive material producing bright green birefringence also developed outward from AEF precipitates. Amyloid built upon AEF in this manner was composed of full-length SAA. No amyloid was produced in cultures treated with either SAA or AEF alone. SAA and SAA peptides processed in the C-terminal region were the most prominent proteins in the glycerol-extracted AEF preparation. Conclusion. AEF binds to fibroblast monolayers and acts as a sink for SAA. SAA that collects on AEF assembles into an amyloid structure. Thus, it is concluded that AEF serves as both a nidus and a template for amyloid formation.

Original languageEnglish
Pages (from-to)1430-1437
Number of pages8
JournalArthritis and Rheumatism
Volume48
Issue number5
DOIs
StatePublished - May 1 2003

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Serum Amyloid A Protein
Amyloid
Fibroblasts
Congo Red
Birefringence
amyloid enhancing factor
Glycerol
Fluorescence Microscopy
Confocal Microscopy
Sodium Dodecyl Sulfate
Sequence Analysis
Culture Media
Immune Sera
Polyacrylamide Gel Electrophoresis

ASJC Scopus subject areas

  • Immunology
  • Rheumatology

Cite this

Amyloid-enhancing factor mediates amyloid formation on fibroblasts via a nidus/template mechanism. / Magy, Nadine; Liepnieks, Juris J.; Benson, Merrill; Kluve-Beckerman, Barbara.

In: Arthritis and Rheumatism, Vol. 48, No. 5, 01.05.2003, p. 1430-1437.

Research output: Contribution to journalArticle

Magy, Nadine ; Liepnieks, Juris J. ; Benson, Merrill ; Kluve-Beckerman, Barbara. / Amyloid-enhancing factor mediates amyloid formation on fibroblasts via a nidus/template mechanism. In: Arthritis and Rheumatism. 2003 ; Vol. 48, No. 5. pp. 1430-1437.
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abstract = "Objective. To determine the mechanism by which amyloid-enhancing factor (AEF) promotes amyloid deposition, and to test whether AEF seeds deposition of serum amyloid A (SAA) and facilitates conversion to beta-sheet structure. Methods. Fibroblasts were cultured with mouse recombinant SAA1.1 and AEF, SAA1.1, or AEF. AEF was prepared as a glycerol extract of spleen from amyloidotic mice. Amyloid was identified by staining with Congo red and examining for green birefringence under polarized light. SAA was localized immunohisto-chemically. Texas Red-labeled SAA was visualized in living cultures by fluorescence confocal microscopy. AEF was characterized by Western blot analysis using anti-SAA antiserum and N-terminal sequence analysis. Subunits comprising amyloid in fibroblast cultures were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results. Amyloid was produced in fibroblast cultures by an AEF-dependent mechanism. AEF, added to culture medium as insoluble protein precipitates, adhered to fibroblast monolayers. SAA bound preferentially to the adherent precipitates. Coincident with SAA binding, precipitates developed an affinity for Congo red. Over time, as more SAA was added, networks of Congo red-positive material producing bright green birefringence also developed outward from AEF precipitates. Amyloid built upon AEF in this manner was composed of full-length SAA. No amyloid was produced in cultures treated with either SAA or AEF alone. SAA and SAA peptides processed in the C-terminal region were the most prominent proteins in the glycerol-extracted AEF preparation. Conclusion. AEF binds to fibroblast monolayers and acts as a sink for SAA. SAA that collects on AEF assembles into an amyloid structure. Thus, it is concluded that AEF serves as both a nidus and a template for amyloid formation.",
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