The Toll-like receptor 2 (TLR2) ligand FSL-1 is internalized via the clathrin-dependent endocytic pathway triggered by CD14 and CD36 but not by TLR2
The Toll-like receptor 2 (TLR2) ligand FSL-1 is internalized via the clathrin-dependent endocytic pathway triggered by CD14 and CD36 but not by TLR2
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DOI：
10.1111/j.1365-2567.2009.03232.x
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发表时间：
2010-06-01
期刊：
影响因子：
6.4
通讯作者：
Shibata, Ken-ichiro
中科院分区：
文献类型：
--
作者：
Shamsul, Haque M.;Hasebe, Akira;Shibata, Ken-ichiro
P>人们对 Toll 样受体 (TLR) 配体在被 TLR 识别后如何进行加工知之甚少。因此，本研究旨在研究 TLR2 配体 FSL-1 在被 TLR2 识别后如何在巨噬细胞中进行加工。 FSL-1 被内化到小鼠巨噬细胞系 RAW264.7 中。抑制网格蛋白依赖性内吞作用的氯丙嗪和甲基-β-环糊精均以剂量依赖性方式减少RAW264.7细胞对FSL-1的摄取，但抑制小凹和脂筏依赖性内吞作用的制霉菌素却没有。在 RAW264.7 细胞的胞浆中，FSL-1 与网格蛋白共定位，但不与 TLR2 共定位。这些结果表明 FSL-1 的内化是网格蛋白依赖性的。此外，FSL-1 被 TLR2 缺陷小鼠的腹膜巨噬细胞内化。 FSL-1被转染CD14或CD36的人胚胎肾293细胞内化，但未被未转染的细胞内化。此外，转染子中 CD14 或 CD36 的敲除也会减少 FSL-1 的摄取。在这项研究中，我们认为（i）FSL-1通过网格蛋白依赖性内吞途径内化到巨噬细胞中，（ii）无论TLR2是否存在，巨噬细胞都会摄取FSL-1，（iii）CD14和CD36负责FSL-1的内化。
P>Little is known of how Toll-like receptor (TLR) ligands are processed after recognition by TLRs. This study was therefore designed to investigate how the TLR2 ligand FSL-1 is processed in macrophages after recognition by TLR2. FSL-1 was internalized into the murine macrophage cell line, RAW264.7. Both chlorpromazine and methyl-beta-cyclodextrin, which inhibit clathrin-dependent endocytosis, reduced FSL-1 uptake by RAW264.7 cells in a dose-dependent manner but nystatin, which inhibits caveolae- and lipid raft-dependent endocytosis, did not. FSL-1 was co-localized with clathrin but not with TLR2 in the cytosol of RAW264.7 cells. These results suggest that internalization of FSL-1 is clathrin dependent. In addition, FSL-1 was internalized by peritoneal macrophages from TLR2-deficient mice. FSL-1 was internalized by human embryonic kidney 293 cells transfected with CD14 or CD36 but not by the non-transfected cells. Also, knockdown of CD14 or CD36 in the transfectants reduced FSL-1 uptake. In this study, we suggest that (i) FSL-1 is internalized into macrophages via a clathrin-dependent endocytic pathway, (ii) the FSL-1 uptake by macrophages occurs irrespective of the presence of TLR2, and (iii) CD14 and CD36 are responsible for the internalization of FSL-1.