Podocalyxin enhances the adherence of cells to platelets

10 pages.Podocalyxin (PODXL) is a mucin protein of the CD34 family expressed in kidney glomerular podocytes, vascular endothelium, progenitor bone marrow and tumor cells. It is assumed that PODXL plays an anti-adherent role in kidney podocytes. CHO cells stably expressing human PODXL (CHO-PODXL) or human tumor cells (Tera-1) inherently expressing PODXL showed increased adherence to platelets. The adherence of cells was inhibited (70%) by blockers of platelet P-selectin, prevented by the soluble ectodomain of human PODXL (PODXL-Δ) or by the arginine-glycine-aspartate (RGDS) peptide and partially impeded by inhibition of integrin αVβ3/αVβ5, suggesting a coordinated action of P-selectin and integrins. Colocalization of platelet P-selectin and PODXL expressed on CHO cells was demonstrated by confocal immunofluorescence. No adherence to platelets was observed when PODXL was expressed in glycomutant CHO cells deficient in sialic acid.S. Larrucea held a research contract from the Comunidad de Madrid (08.4/0015.1/2001) and a research tenure track of the CSIC. N. Butta and E. G. Arias-Salgado hold a tenure track grant Ramón y Cajal from the Spanish Ministry of Education and Science (MEC). S. Alonso was recipient of a predoctoral fellowship from the Basque Community of Spain (BF101–40). Supported in part by grants from Spanish MEC (SAF 2004–04345, SAF 2005–01261), FIS (FIS-PI021263 and PI050546), Comunidad de Madrid (08.4/ 0029.1/2003) and Fundación Rodríguez Pascual.Peer reviewe