SRCL/CL-P1 recognizes GalNAc and a carcinoma-associated antigen, Tn antigen.
SRCL /CL-P1 was recently identified as a scavenger receptor with a C-type lectin domain, which was expressed in vascular endothelial cells and could bind to Gram-positive and Gram-negative bacteria, yeast and oxidized LDL. We found that SRCL was expressed in some but not all nurse-like cells examined. Furthermore, to characterize the C-type lectin domain of SRCL, the secreted form of the C-type lectin domain (LEC-AP) of SRCL, which was fused to the signal sequence of IgG and alkaline phosphatase, was expressed in 293/EBNA-1 cells and the culture medium was used for the in vitro binding assay. LEC-AP specifically bound to GalNAc-conjugated gel in a Ca(2+)-dependent manner, and this binding was inhibited by free GalNAc, L-, D-fucose, D-galactose, lactose, and especially T antigen and Tn antigen. Furthermore, we examined whether or not SRCL could take up saccharide-conjugated particles. 293/EBNA-1 cells stably expressing SRCL were found to take up GalNAc but not mannose-conjugated particles on confocal microscopy. The binding of GalNAc-conjugated particles to these cells was quantitatively measured by comparing the x-means of individual cell populations. An approximately 2.1-fold increase in immunofluorescence intensity was observed for the SRCL transfectants compared to control vector transfectants. Our results provide a basis for understanding the scavenger function of SRCL as to carbohydrate-containing ligands.
Yoshida
Tetsuya
T
Discovery Research Laboratories, Shionogi & Co., Ltd., 2-5-1 Mishima, Settsu, Osaka 566-0022, Japan. tetsuya.yoshida@shionogi.co.jp
Tsuruta
Yuji
Y
Iwasaki
Makoto
M
Yamane
Shoji
S
Ochi
Takahiro
T
Suzuki
Ryuji
R
D000116:Acetylgalactosamine / Q000737:chemistry / Q000378:metabolism*; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D037222:Collectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding / Q000235:genetics; D011971:Receptors, Immunologic / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051116:Receptors, Scavenger; D014162:Transfection
D015295:Antigens, Tumor-Associated, Carbohydrate; C422442:COLEC12 protein, human; D037222:Collectins; D011971:Receptors, Immunologic; D051116:Receptors, Scavenger; C040286:Tn antigen; D000116:Acetylgalactosamine