Specific interaction of oxidized low-density lipoprotein with thrombospondin-1 inhibits transforming growth factor-beta from its activation.
Oxidized LDL (Ox-LDL) plays atherogenic roles, whereas thrombospondin-1 (TSP-1) is thought to be anti-atherogenic through activation of TGF-beta that contributes to plaque stabilization. Ox-LDL was prepared by incubating of human LDL with CuSO4. Effect of Ox-LDL on TSP-1-induced TGF-beta activation was examined in the present study. Incubation of Ox-LDL with mouse peritoneal macrophages for 3 days resulted in reduction in amounts of active TGF-beta in the culture medium by 70-78% when compared with that of parallel incubation without Ox-LDL. TSP-1 could enhance conversion of latent TGF-beta1 into active TGF-beta1 in a cell-free system. This TSP-1-mediated latent TGF-beta1 activation was inhibited by 30% by Ox-LDL, suggesting the possible interaction of Ox-LDL with TSP-1. Incubation of TSP-1 with [125I]Ox-LDL or [125I]LDL, followed by immunoprecipitation with an anti-TSP-1 antibody demonstrated that a significant amount of [125I]Ox-LDL was co-precipitated with TSP-1 while precipitation of [125I]LDL was negligible. Furthermore, upon TSP-1-conjugated Sepharose 4B affinity chromatography, both [125I]Ox-LDL and [125I]latent TGF-beta1 bound to the affinity gel were eluted by unlabeled Ox-LDL. These findings indicate that Ox-LDL interacts with TSP-1 and suppresses subsequent TSP-1-dependent TGF-beta activation, revealing a novel atherogenic function of Ox-LDL.
Sakamoto
Yu-ichiro
Y
Department of Medical Biochemistry, Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan. yusaka@kaiju.medic.kumamoto-u.ac.jp
Miyazaki
Akira
A
Tamagawa
Harumi
H
Wang
Guo-Ping
GP
Horiuchi
Seikoh
S
D000818:Animals; D050197:Atherosclerosis / Q000209:etiology; D001792:Blood Platelets / Q000737:chemistry; D002474:Cell-Free System; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D002846:Chromatography, Affinity; D003470:Culture Media / Q000737:chemistry; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D053779:Latent TGF-beta Binding Proteins; D008077:Lipoproteins, LDL / Q000378:metabolism / Q000494:pharmacology*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011994:Recombinant Proteins / Q000378:metabolism; D019700:Thrombospondin 1 / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D053773:Transforming Growth Factor beta1
D003470:Culture Media; D047908:Intracellular Signaling Peptides and Proteins; D053779:Latent TGF-beta Binding Proteins; D008077:Lipoproteins, LDL; D011994:Recombinant Proteins; C508960:TGFB1 protein, human; C508961:Tgfb1 protein, mouse; D019700:Thrombospondin 1; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; C099252:oxidized low density lipoprotein