Differential expression of functional nucleoside transporters in non-differentiated and differentiated human endothelial progenitor cells
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Date
2010
Journal Title
Journal ISSN
Volume Title
Publisher
W B SAUNDERS CO LTD
Abstract
Extracellular adenosine removal is via human equilibrative nucleoside transporters 1 (hENT1) and 2 (hENT2) in the endothelium, thus regulating adenosine-induced revascularization and angiogenesis. Since human endothelial progenitor cells (hEPCs) promote revascularization, we hypothesize differential expression of nucleoside transporters in hEPCs. hEPCs were cultured 3 (hEPC-3d) or 14 (hEPC-14d) days. RT-PCR for prominin 1, CD34, octamer-4, kinase insert domain receptor, oxidized low-density lipoprotein (lectin-like) receptor 1 and tyrosine endothelial kinase was used to evaluate phenotypic differentiation. Flow cytometry was used to estimate CD34(+)/KDR- (non-differentiated), CD34(-)/KDR+ (differentiated) or CD34(+)/KDR+ (mixed) cell populations. Adenosine transport was measured in absence or presence of sodium, S-(4-nitrobenzyl)-6-thio-inosine (NBTI, 1-10 mu M), inosine, hypoxanthine or guanine (0.1-5 mM), hENTs protein abundance by western blot, and hENTs, hCNT1, hCNT2 and hCNT3 mRNA expression by real time RT-PCR. hEPC-3d cells were CD34(+)/KDR- compared with hEPC-14d cells that were CD34(-)/KDR+ hEPC-3d cells exhibit hENT1-like adenosine transport (NBTI-sensitive, Na+-independent), which is absent in hEPC-14d cells. hEPC-14d cells exhibit two transport components: component 1 (NBTI insensitive, Na+-independent) and component 2 (NBTI insensitive, Na+-dependent, Hill coefficient similar to 1.8), the latter resembling CNT3-like transport. hEPC-3d cells express hENT1 protein and mRNA, which is reduced (similar to 90%) in hEPC-14d cells, but instead only hCNT3 mRNA is expressed in this cell type. hENT2, hCNT1 and hCNT2 were undetectable in hEPCs. Thus, hEPCs exhibit a differential expression of hENT1 and hCNT3 functional nucleoside transporters, which could be related with its differentiation stage. (c) 2010 Elsevier Ltd. All rights reserved.
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Keywords
Endothelial progenitor cells, Adenosine, Transport, Differentiation, SMOOTH-MUSCLE-CELLS, ADENOSINE TRANSPORT, NITRIC-OXIDE, ANGIOGENESIS, PREECLAMPSIA, VASCULOGENESIS, DYSFUNCTION, INHIBITORS, PREGNANCY, LEUKEMIA