title: Renal cells activate the platelet receptor CLEC-2 through podoplanin.
abstract: We have recently shown that the C-type lectin-like receptor, CLEC-2, is expressed on platelets and that it mediates powerful platelet aggregation by the snake venom toxin rhodocytin. In addition, we have provided indirect evidence for an endogenous ligand for CLEC-2 in renal cells expressing HIV-1. This putative ligand facilitates transmission of HIV through its incorporation into the viral envelope and binding to CLEC-2 on platelets. The aim of the present study was to identify the ligand on these cells which binds to CLEC-2 on platelets. Recombinant CLEC-2 exhibits specific binding to HEK-293T (human embryonic kidney) cells in which the HIV can be grown. Furthermore, HEK-293T cells activate both platelets and CLEC-2-transfected DT-40 B-cells. The transmembrane protein podoplanin was identified on HEK-293T cells and was demonstrated to mediate both binding of HEK-293T cells to CLEC-2 and HEK-293T cell activation of CLEC-2-transfected DT-40 B-cells. Podoplanin is expressed on renal cells (podocytes). Furthermore, a direct interaction between CLEC-2 and podoplanin was confirmed using surface plasmon resonance and was shown to be independent of glycosylation of CLEC-2. The interaction has an affinity of 24.5+/-3.7 microM. The present study identifies podoplanin as a ligand for CLEC-2 on renal cells.
authors.affiliation: Henry Wellcome Building for Molecular Physiology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
authors.forename: Charita M
authors.initials: CM
authors.lastname: Christou
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Pearce
authors.forename: Aleksandra A
authors.initials: AA
authors.lastname: Watson
authors.forename: Anita R
authors.initials: AR
authors.lastname: Mistry
authors.forename: Alice Y
authors.initials: AY
authors.lastname: Pollitt
authors.forename: Angharad E
authors.initials: AE
authors.lastname: Fenton-May
authors.forename: Louise A
authors.initials: LA
authors.lastname: Johnson
authors.forename: David G
authors.initials: DG
authors.lastname: Jackson
authors.forename: Steve P
authors.initials: SP
authors.lastname: Watson
authors.forename: Chris A
authors.initials: CA
authors.lastname: O'Callaghan
mesh_terms: D002460:Cell Line; D003001:Cloning, Molecular; D006031:Glycosylation; D006801:Humans; D007668:Kidney / Q000737:chemistry / Q000166:cytology*; D037181:Lectins, C-Type / Q000378:metabolism*; D008024:Ligands; D008562:Membrane Glycoproteins / Q000032:analysis / Q000378:metabolism*; D050199:Podocytes / Q000737:chemistry; D011485:Protein Binding; D020349:Surface Plasmon Resonance; D014162:Transfection; D000098853:Podoplanin
chemical_list: D037181:Lectins, C-Type; D008024:Ligands; D008562:Membrane Glycoproteins; C104778:CLEC2B protein, human; C117468:PDPN protein, human; D000098853:Podoplanin