The Membrane-type Collectin CL-P1 Is a Scavenger Receptor on Vascular Endothelial Cells

Abstract

Collectins are a family of C-type lectins that have collagen-like sequences and carbohydrate recognition domains (CRD). They are involved in host defense through their ability to bind to carbohydrate antigens of microorganisms. The scavenger receptors type A and MARCO are classical type scavenger receptors that have internal collagen-like domains. Here we describe a new scavenger receptor that is a membrane-type collectin from placenta (collectin placenta 1 (CL-P1)), which has a typical collectin collagen-like domain and a CRD. The cDNA has an insert of about 2.2 kilobases coding for a protein containing 742 amino acid residues. The deduced amino acid sequence shows that CL-P1 is a type II membrane protein, has a coiled-coil region, a collagen-like domain, and a CRD. It resembles type A scavenger receptors because the scavenger receptor cysteine-rich domain is replaced by a CRD. Northern analyses, reverse transcription-polymerase chain reaction, and immunohistochemistry show that CL-P1 is expressed in vascular endothelial cells but not in macrophages. By immunoblotting and flow cytometry CL-P1 appears to be a membrane glycoprotein of about 140 kDa in human umbilical vein or arterial endothelial cells, placental membrane extracts, and CL-P1 transfected Chinese hamster ovary cells. We found that CL-P1 can bind and phagocytose not only bacteria (Escherichia coli and Staphylococcus aureus) but also yeast (Saccharomyces cerevisiae). Furthermore, it reacts with oxidized low density lipoprotein (OxLDL) but not with acetylated LDL (AcLDL). These binding activities are inhibited by polyanionic ligands (polyinosinic acid, polyguanylic acid, dextran sulfate) and OxLDL but not by polycationic ligands (polyadenylic acid or polycytidylic acid), LDL, or AcLDL. These results indicate that CL-P1 might play important roles in host defenses that are different from those of soluble collectins in innate immunity.

Transcriptional expression levels of chicken collectins are affected by avian influenza A virus inoculation

“…However, the chicken genome did not seem to contain a homologue for the second pulmonary collectin SP-D. In addition, chicken collectins 1, 2 and 3 were found which resemble the mammalian collectin liver 1 (CL-L1) (Ohtani et al, 1999), collectin kidney 1 (CL-K1) (Keshi et al, 2006) and collectin placenta 1 (CL-P1) (Ohtani et al, 2001). The biological roles of CL-L1 and CL-K1 have not been determined yet, leaving no indication for a possible role of chicken collectins cCL-1 and cCL-2.…”

Deterioration of atherosclerosis in mice lacking angiotensin II type 1A receptor in bone marrow-derived cells

“…Interestingly, our microarray results revealed a marked increase in class A scavenger receptor, Colec12/SRCL/CL-P1 and MARCO in AT1-KO macrophages (Figure 5a). Colec12 has been reported to react with oxidized LDL 38 and MARCO was recently shown to have profound effects on binding of acetylated LDL. 39 Little is known about the role of Ang II on phagocytosis by macrophages.…”

Scavenger receptor CL-P1 mediates endocytosis by associating with AP-2μ2

“…Monoclonal antibody to clathrin heavy chain, -adaptin, -adaptin, 2 (AP50) and dynamin-2 were purchased from BD Biosciences (San Jose, CA). Monoclonal and polyclonal antibodies to CL-P1 (10,12) were obtained using the recombinant carbohydrate recognition domain (CRD) of human CL-P1 in E. coli. Immunoaffinity purification of antibodies was used to purify antigen-specific antibodies from a preparation of polyclonal antibodies to CL-P1.…”

“…Interestingly, CL-P1 can also bind and endocytose OxLDL but not to AcLDL as other modified-LDLs in endothelial cells (10). LOX-1 is a class E scavenger receptor that was originally considered as the major and only receptor for OxLDL on endothelial cells (7).…”

“…We recently identified collectin placenta 1 (CL-P1) from placental cDNA, which is a C-type lectin containing an inner collagen-like region (10). CL-P1 is a type II transmembrane protein with a coiled-coil domain, a collagen-like domain, and a carbohydrate recognition domain (CRD).…”