Scavenger Receptor Collectin Placenta 1 (CL-P1) Predominantly Mediates Zymosan Phagocytosis by Human Vascular Endothelial Cells

Abstract

Collectin placenta 1 (CL-P1), a recently discovered scavenger receptor, mediates the uptake of oxidized low density lipoprotein and microbes. In this study, we investigated CL-P1-mediated binding and ingestion of yeast-derived zymosan bioparticles using Chinese hamster ovary (CHO) cells stably expressing human CL-P1 (CHO/CL-P1) and human vascular endothelial cells constitutively expressed CL-P1. The uptake of zymosan by CHO/CL-P1 was dependent upon the level of CL-P1 expressed on the membrane and was inhibited by cytochalasin D and wortmannin. The binding of zymosan was also inhibited by ligands of other scavenger receptors such as poly(I) and dextran sulfate. Real time reverse transcription-PCR analyses showed that other scavenger receptors, namely LOX-1, Stabilin-2, or macrophage receptor with collagenous structure (MARCO), were not expressed in human umbilical vein endothelial cells isolated from different individuals. Nonopsonic zymosan ingestion was inhibited in three primary cultured vascular endothelial cells, including different human umbilical vein endothelial cells from nine individuals treated with CL-P1 small interfering RNAs, although small interfering RNAs of other scavenger receptors had no effect on zymosan uptake in these cells. Furthermore, we confirmed that CL-P1 is expressed in human and murine vascular endothelial layers. Our results demonstrated that CL-P1 predominantly mediated phagocytosis for fungi in vascular endothelia.Scavenger receptors are integral membrane proteins consisting at least eight different subclasses (Class A to Class H), with little amino acid sequence homology, that bind to a wide variety of ligands, including modified or oxidized low density lipoproteins (oxLDLs), 2 apoptotic cells, and microbial pathogens (1). Among these ligands, oxLDLs are considered to have an important role in interactions with endothelial cells, macrophages, and smooth muscle cells in the development of atherosclerosis according to Ross's response-to-injury hypothesis (2, 3). Vascular endothelial cells express several distinct scavenger receptors, such as SR-BI (4 -6), LOX-1 (7), SREC (8), FEEL-1/stabilin-1, and FEEL-2/stabilin-2 (9).Using placental cDNA, we recently identified CL-P1 (10), a type II transmembrane protein with a coiled-coil, a collagenlike domain, and a carbohydrate recognition domain (CRD) and showed it to be a scavenger receptor, in addition to its role as a collectin (Colec12). This molecule resembles a Class A scavenger receptor (SR-A) in its structure except for the replacement of the cysteine-rich domain by a CRD (11). CL-P1 can bind to oxLDL without interacting with other modified LDLs such as acetyl-LDL. Interestingly, we found that CL-P1 expression in HUVECs was up-regulated after the induction of oxidative stress in vitro and was increased in aortic endothelia in a rat ischemia-reperfusion model (12). Another reported finding on the ability of CL-P1 to mediate the binding of yeast, as well as Gram-negative and -positive bacteria in CL-P1-transfected CHO cells, strongly ...

PtLGBP, a pattern recognition receptor inPortunus trituberculatusinvolved in the immune response against different challenges

“…this multifunction in pathogen recognition has been suspected to be abolished because of protein functional differentiation in arthropods. through pathogen recognition, Prrs further mediate in opsonic effect, benefiting pathogen cleaning, such as agglutination mediated by c-type lectins [2,26,27], antibacterial activity mediated by PGrP-sB1 [16] and sr-enhanced phagocytosis [8]. PtLGBP exhibited obvious agglutination activity against Gram-negative bacteria V. parahaemolyticus, V. alginolyticus, and e. coli; Gram-positive bacteria B. megaterium; and fungi s. cerevisiae.…”

Phagocytosis-dependent and independent mechanisms underlie the microglial cell damage caused by carbon nanotube agglomerates

“…Phagocytosis and macropinocytosis are closely related processes (Swanson, 2008(Swanson, , 2014, however, the regulatory architecture of these processes are not fully understood (Bloomfield et al, 2015). These processes are triggered by the interaction between the particles and various kinds of receptors (Jang et al, 2009;Ramirez-Ortiz et al, 2013) As for CNTs, phagocytosis of SWCNTs by macrophages (Dong et al, 2013) and macropinocytosis of MWCNTs through macrophage receptor with collagenous structure (MARCO) (Hirano et al, 2012) have been reported, while the interaction of CNTs with scavenger receptors (ScRs), which are important for both phagocytosis and micropinocytosis, has also been reported (Wang et al, 2012). The surface modification, size, and shape of the CNTs or their agglomerates may affect their internalization pathways.…”

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

“…Wortmannin, a phagocytosis inhibitor (12) or Genistein, an inhibitor of caveolae-dependent uptake (18,19), had no effect on the endocytosis of ligands for CL-P1 (Fig. 6A, B).…”

“…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.…”

“…The ability of CL-P1 to bind and phagocytose Gram-negative and Gram-positive bacteria, as well as to yeast, strongly suggests a role for CL-P1 in host defense. Recently, we demonstrated an important role of scavenger receptor CL-P1 in zymosan phagocytosis by several vascular endothelial cells (12).…”