Renal cells activate the platelet receptor CLEC-2 through podoplanin

• Published in: Biochemical journal Vol. 411; no. 1; p. 133
• Main Authors: Christou, Charita M, Pearce, Andrew C, Watson, Aleksandra A, Mistry, Anita R, Pollitt, Alice Y, Fenton-May, Angharad E, Johnson, Louise A, Jackson, David G, Watson, Steve P, O'Callaghan, Chris A
• Format: Journal Article
• Language: English
• Published: England 01.04.2008
• Subjects: Cell Line; Cloning, Molecular; Glycosylation; Humans; Kidney - chemistry; Kidney - cytology; Lectins, C-Type - metabolism; Ligands; Membrane Glycoproteins - analysis; Membrane Glycoproteins - metabolism; Podocytes - chemistry; Protein Binding; Surface Plasmon Resonance; Transfection
• DOI: 10.1042/BJ20071216

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.