원문정보
초록
영어
Lipid rafts are membrane microdomains enriched in saturated phospholipid, sphingolipid, and cholesterol. Pattern Recognition Receptors (PRRs) such as Toll-like Receptors (TLRs), dectin-1 or DC-SIGN are expressed on lipid rafts. SIGN-R1, a PRR, is a homologue of human DC-SIGN and expressed at high levels on macrophages within the marginal zone of the spleen and lymph node medulla, mediating the uptake of pneumococcal capsular polysaccharides (CPSs). Here we showed that SIGN-R1 was expressed in lipid rafts of SIGN-R1 transfectant cell lines in vitro as well as in lipid rafts of spleen or lymphnodes in vivo. It was identified that SIGN-R1 recruited its ligands such as dextran and pneumococcal capsular polysaccharides in vitro. Additionally, it was found that SIGN-R1 was multimerized in lipid rafts with the intravenous administration of S. pneumoniae type 14 or its capsular polysaccharide (CPS14) in vivo. However, the multimerization of SIGN-R1 was not occurred against CPS-depleted S. pneumoniae type 14 or another gram-positive bacteria, Streptococcus aureus. All of these results suggested that the localization of SIGN-R1 in lipid rafts might be important for protecting host against S. pneumoniae, activation its defense mechanism including the multimerization of SIGN-R1. Currently, further studies are in investigation as follows. 1) Whether SIGN-R1 could mediate complement activation against its ligands in lipid rafts? 2) Whether SIGN-R1 mediates a specific signaling from lipid rafts against its ligand? 3) Whether SIGN-R1 mediates the generation of a specific cytokine from lipid rafts against its ligands?