Expression and tissue localization of collectin placenta 1 (CL-P1, SRCL) in human tissues.
Collectin placenta-1 (CL-P1), also known as scavenger receptor with C-type lectin (SRCL), is a type II membrane glycoprotein that shares structural features with both collectins and type A scavenger receptors. CL-P1 was originally cloned from the placenta and found to be associated with endothelial cells. It binds via its lectin domain to desialyated Lewis X containing glycoproteins and it is able to facilitate internalization of bound ligands. Via positively charged residues in the collagen-like region it binds to negatively charged components of microbial membranes. It has previously been proposed that CL-P1 plays a role in the host defense system and in the clearance of glycoproteins from the blood. With the aims of determining the detailed tissue expression of human CL-P1 we expressed CL-P1 recombinantly in both E. coli and CHO cells, and raised monoclonal antibodies against human CL-P1. Three monoclonal antibodies were characterized and used in immunohistochemical analyses of a panel of cryo- and formalin-fixed sections. We find that CL-P1 mainly associates with cytotrophoblasts and syncytiotrophoblasts of the placenta, alveolar macrophages and to a less degree with macrophage-like and stromal cells of the tonsils. By real-time RT-PCR we verified that the placenta is also the main organ of CL-P1 synthesis. The only source of endothelial cells whereto CL-P1 associates are umbilical cord vein endothelial cells (human umbilical vein endothelial cells, HUVEC). In vitro cultured HUVECs express both the CL-P1 mRNA and show anti-CL-P1 immunoreactivity but CL-P1 locates mainly to the cytosol and not to the membrane of these cells. We conclude that CL-P1 is not a common membrane protein on endothelial cells found in normal tissues under steady state conditions.
Selman
Lana
L
Department of Immunology & Microbiology, University of Southern Denmark, Winsloewparken 21-1, DK-5000 Odense C, Denmark.
Skjodt
Karsten
K
Nielsen
Ole
O
Floridon
Charlotte
C
Holmskov
Uffe
U
Hansen
Soren
S
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D016466:CHO Cells; D002460:Cell Line; D037222:Collectins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D016612:Paraffin Embedding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051116:Receptors, Scavenger / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
D000911:Antibodies, Monoclonal; C422442:COLEC12 protein, human; D037222:Collectins; D012333:RNA, Messenger; D051116:Receptors, Scavenger; D011994:Recombinant Proteins