Endothelial localization of receptor tyrosine phosphatase, ECRTP/DEP-1, indeveloping and mature renal vasculature

Developmental assembly of the renal microvasculature requires spatially and temporally coordinated migration, assembly, differentiation, and maturatio n of endothelial cells in the context of adjacent epithelial and mesangial cells. Tn this study, endothelial expression and distribution of the recept or tyrosine phosphatase ECRTP/DEP-1 were evaluated during and after develop mental assembly of the renal microvasculature. Monoclonal antibodies agains t ECRTP/DEP-1 ectodomain epitopes localize its expression to membrane surfa ces of endothelial cells in glomerular, peritubular capillary, and arterial renal sites of mature human and murine kidney. During kidney development, ECRTP/DEP-1 immunostaining is evident on a subpopulation of metanephric mes enchymal cells and on putative progenitors of glomerular capillary endothel ial cells early in their recruitment to developing glomeruli. ECRTP/DEP-1 i s prominently displayed on luminal membrane surfaces with punctate accumula tions at inter-endothelial contacts that overlap with Vascular endothelial- cadherin staining. ECRTP/DEP-1 is recruited to inter-endothelial contacts i n con fluent cultured human renal and dermal microvascular endothelial cell s, yet experimental dissociation of vascular endothelial-cadherin from endo thelial junctional complexes fails to redistribute ECRTP/DEP-1. These findi ngs indicate that ECRTP/DEP-1 is expressed in anticipation of glomerular ca pillary endothelial recruitment during development, and suggest that ECRTP/ DEP-1 ectodomain interacts with endothelial surface ligands that are engage d by cell-cell contact.