Involvement of cholesterol-enriched microdomains in class A scavenger receptor-mediated responses in human macrophages

作者：Kiyanagi Takashi; Iwabuchi Kazuhisa^*; Shimada Kazunori; Hirose Kuniaki; Miyazaki Tetsuro; Sumiyoshi Katsuhiko; Iwahara Chihiro; Nakayama Hitoshi; Masuda Hiromi; Mokuno Hiroshi; Sato Satoshi; Daida Hiroyuki

来源：Atherosclerosis, 2011, 215(1): 60-69.

DOI：10.1016/j.atherosclerosis.2010.10.019

• Lipid raft
• Cholesterol-enriched microdomain
• Scavenger receptor
• Macrophages
• Atherosclerosis
• Modified LDL

Objective: Lipid rafts are cholesterol-enriched microdomains on cell membranes. We hypothesized that these microdomains could involve modified low-density lipoprotein (LDL) uptake.
Methods and results: Co-localizations of cholesterol-enriched microdomains and CD204 during the uptake of acetyl LDL (AcLDL) and oxidized LDL were observed using Alexa488-labeled polyethylene glycol cholesteryl ester, which is a sensitive probe used to analyze the dynamics of cholesterol-rich lipid microdomains in living cells. The lipid raft disruptors, methyl-beta cyclodextrin and filipin, inhibited the uptake of AcLDL. CD204 siRNA treatments significantly reduced AcLDL uptake by 80%. We also demonstrated the presence of CD204 in the detergent-resistant membrane fraction (DRM) by immunoblotting analysis. The ratio of CD204/flotillin-1 in DRM was increased 11.5-fold by modified LDL administration. The PI3 kinase inhibitor LY294002, but not the Src kinase inhibitor PP1 or the G alpha i/o inhibitor pertussis toxin, inhibited modified LDL uptake. The production of interleukin (IL)-8, but not CCL2, CXCL2, CXCL3, IL-6 or tumor necrosis factor-alpha was increased by AcLDL administration. The AcLDL-induced IL-8 production was inhibited by LY294002 and filipin.
Conclusions: These data firstly demonstrated that PI3 kinase-associated cholesterol-enriched microdomains are involved in CD204-mediated modified LDL uptake in human macrophages. Cholesterol-enriched microdomains may play a critical role in inflammatory processes.

• 出版日期2011-3