Amyloid enhancing factor activity is associated with ubiquitin.
Crude amyloid enhancing factor (AEF) drastically reduces the pre-amyloid phase on passive transfer and induces amyloid deposition in the recipient mice in 48-120 h. We attempted to purify AEF from murine amyloidotic liver and spleen extracts by using gel filtration, preparative sodium dodecyl sulphate-polyacrylamide gel electrophoresis and ion exchange chromatography and isolated a 5.5 kDa peptide. In the mouse bioassay, this peptide induced accelerated splenic AA deposition in a dose-dependent manner. Based on structural, electrophoretic and immunochemical criteria the peptide was identified as ubiquitin. A polyclonal rabbit anti-bovine ubiquitin IgG antibody (RABU) abolished the in vivo AEF activity of crude murine AEF in a dose-dependent manner. Monomeric ubiquitin and its large molecular weight adducts were isolated from crude AEF using cyanogen bromide-activated sepharose conjugated to RABU and size exclusion chromatography methods. These were assayed and were found to possess AEF activity. Furthermore, increased levels of ubiquitin, a phenomenon similar to that of AEF, were detected by immunocytochemistry in mouse peritoneal leucocytes prior to and during amyloid deposition. Since AEF shares a number of biological and functional properties with ubiquitin, we suggest a possible role of ubiquitin as an AEF, and that serum amyloid protein A and ubiquitin, the two reactants generated during inflammatory stress conditions, may converge to induce AA amyloid deposition.
Alizadeh-Khiavi
K
K
Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada.
Normand
J
J
Chronopoulos
S
S
Ali
A
A
Ali-Khan
Z
Z
D000210:Acute-Phase Reaction / Q000378:metabolism; D000595:Amino Acid Sequence; D000686:Amyloidosis / Q000378:metabolism; D000818:Animals; D002364:Caseins / Q000494:pharmacology; D004195:Disease Models, Animal; D006023:Glycoproteins / Q000737:chemistry* / Q000302:isolation & purification; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D014452:Ubiquitins / Q000737:chemistry*
D002364:Caseins; D006023:Glycoproteins; D010446:Peptide Fragments; D014452:Ubiquitins; C046748:amyloid enhancing factor; C018135:proteose-peptone