title: The novel endocytic and phagocytic C-Type lectin receptor DCL-1/CD302 on macrophages is colocalized with F-actin, suggesting a role in cell adhesion and migration.
abstract: C-type lectin receptors play important roles in mononuclear phagocytes, which link innate and adaptive immunity. In this study we describe characterization of the novel type I transmembrane C-type lectin DCL-1/CD302 at the molecular and cellular levels. DCL-1 protein was highly conserved among the human, mouse, and rat orthologs. The human DCL-1 (hDCl-1) gene, composed of six exons, was located in a cluster of type I transmembrane C-type lectin genes on chromosomal band 2q24. Multiple tissue expression array, RT-PCR, and FACS analysis using new anti-hDCL-1 mAbs established that DCL-1 expression in leukocytes was restricted to monocytes, macrophages, granulocytes, and dendritic cells, although DCL-1 mRNA was present in many tissues. Stable hDCL-1 Chinese hamster ovary cell transfectants endocytosed FITC-conjugated anti-hDCL-1 mAb rapidly (t(1/2) = 20 min) and phagocytosed anti-hDCL-1 mAb-coated microbeads, indicating that DCL-1 may act as an Ag uptake receptor. However, anti-DCL-1 mAb-coated microbead binding and subsequent phagocytic uptake by macrophages was approximately 8-fold less efficient than that of anti-macrophage mannose receptor (MMR/CD206) or anti-DEC-205/CD205 mAb-coated microbeads. Confocal studies showed that DCL-1 colocalized with F-actin in filopodia, lamellipodia, and podosomes in macrophages and that this was unaffected by cytochalasin D, whereas the MMR/CD206 and DEC-205/CD205 did not colocalize with F-actin. Furthermore, when transiently expressed in COS-1 cells, DCL-1-EGFP colocalized with F-actin at the cellular cortex and microvilli. These data suggest that hDCL-1 is an unconventional lectin receptor that plays roles not only in endocytosis/phagocytosis but also in cell adhesion and migration and thus may become a target for therapeutic manipulation.
authors.affiliation: Dendritic Cell Program, Mater Medical Research Institute, South Brisbane, Queensland, Australia.
authors.forename: Masato
authors.initials: M
authors.lastname: Kato
authors.forename: Seema
authors.initials: S
authors.lastname: Khan
authors.forename: Elisabetta
authors.initials: E
authors.lastname: d'Aniello
authors.forename: Kylie J
authors.initials: KJ
authors.lastname: McDonald
authors.forename: Derek N J
authors.initials: DN
authors.lastname: Hart
mesh_terms: D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement; D017124:Conserved Sequence; D006224:Cricetinae; D003713:Dendritic Cells / Q000378:metabolism; D004705:Endocytosis; D006801:Humans; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010587:Phagocytosis; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D000199:Actins; D000911:Antibodies, Monoclonal; C477741:CD302 protein, human; C524565:Cd302 protein, rat; C470572:Dcl1 protein, mouse; D037181:Lectins, C-Type; D008565:Membrane Proteins; D011956:Receptors, Cell Surface