Modification of beta 2-microglobulin with D-glucose or 3-deoxyglucosone inhibits A beta 2M amyloid fibril extension in vitro.
beta 2-microglobulin (beta 2M) is a major constituent of amyloid fibrils (fA beta 2M) deposited in patients with A beta 2M amyloidosis. Recently, advanced glycation end products (AGE) of beta 2M and fA beta 2M have been suggested to play an important role in the pathogenesis of A beta 2M amyloidosis. We first characterized the states of AGE modification of fA beta 2M. Western blot analysis with a monoclonal anti-AGE antibody showed that purified fA beta 2M was naturally modified with AGE. Immunohistochemical studies of amyloid-deposited tissue have revealed a patchy distribution of the AGE-modified area in the amyloid deposits. Then we modified beta 2-m either with D-glucose or with 3-deoxyglucosone (3-DG) and investigated the effect of these modification on fA beta 2M extension in vitro, using the recently established first-order kinetic model of fA beta 2M extension in vitro. Western blot analysis and enzyme linked immunosorbent assay with a monoclonal anti-AGE antibody showed that these sugar-modified beta 2M contained AGE. During the incubation of fA beta 2M with native beta 2-m at 37 degrees C, the fluorescence of thioflavin T increased without a lag phase and proceeded to equilibrium. On the contrary, only a slight increase in fluorescence was observed during the incubation of fA beta 2M with sugar-modified beta 2M. Moreover, sugar-modified beta 2M exhibited a dose-dependent inhibitory effect on the extension reaction of fA beta 2M with native beta 2M. These results may suggest that in some in vivo situations, the modification of beta 2-m with AGE could play an inhibitory role for the formation of fA beta 2M.
Hashimoto
N
N
Department of Clinical and Laboratory Medicine, Fukui Medical University, Japan.
Naiki
H
H
Gejyo
F
F
D000682:Amyloid / Q000737:chemistry*; D000686:Amyloidosis / Q000378:metabolism; D052160:Benzothiazoles; D015153:Blotting, Western; D003847:Deoxyglucose / Q000031:analogs & derivatives* / Q000737:chemistry; D005947:Glucose / Q000737:chemistry*; D017127:Glycation End Products, Advanced / Q000737:chemistry; D006801:Humans; D007150:Immunohistochemistry; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011151:Popliteal Cyst / Q000378:metabolism / Q000473:pathology; D013050:Spectrometry, Fluorescence; D013844:Thiazoles / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
D000682:Amyloid; D052160:Benzothiazoles; D017127:Glycation End Products, Advanced; D013844:Thiazoles; D001613:beta 2-Microglobulin; C009462:thioflavin T; D003847:Deoxyglucose; C016350:3-deoxyglucosone; D005947:Glucose