title: Differential regulation of telomerase in endothelial cells by fibroblast growth factor-2 and vascular endothelial growth factor-a: association with replicative life span.
abstract: In cultured human umbilical vein endothelial cells (HUVECs), fibroblast growth factor-2 (FGF-2), but not vascular endothelial growth factor-A (VEGF-A), upregulates telomerase activity. Here, we examined the functional significance of this differential regulation on the replicative life span of HUVECs. HUVECs were serially passaged until senescence under four different conditions: (1) EGM-2, a medium containing both VEGF-A and FGF-2; (2) basal medium (BM), consisting of EGM-2 devoid of FGF-2 and VEGF-A; (3) BM supplemented with FGF-2; and (4) BM supplemented with VEGF-A. Cells cultured in BM demonstrated decreased growth rate and ceased to proliferate at approximately 15 population doublings (PDs), whereas those cultured with VEGF-A alone initially proliferated vigorously but arrested growth abruptly at a PD level comparable with cultures grown in BM. In contrast, cells maintained in EGM-2 or in BM/FGF-2 attained a normal replicative life span (approximately 40 PDs). These differences in replicative behavior were reflected by the early appearance of a senescent phenotype in cultures grown in BM or BM/VEGF-A. HUVECs grown in the presence of VEGF-A alone have a decreased life span compared with cultures maintained with FGF-2. This suggests that the upregulation of telomerase activity by FGF-2, an effect not achieved with VEGF-A, plays a functional role in preventing the early onset of senescence.
authors.affiliation: Department of Medicine, University College London, United Kingdom.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Trivier
authors.forename: David J
authors.initials: DJ
authors.lastname: Kurz
authors.forename: Ying
authors.initials: Y
authors.lastname: Hong
authors.forename: Hsiu-Lin
authors.initials: HL
authors.lastname: Huang
authors.forename: Jorge D
authors.initials: JD
authors.lastname: Erusalimsky
mesh_terms: D002455:Cell Division; D002478:Cells, Cultured; D016922:Cellular Senescence; D003470:Culture Media / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D010641:Phenotype; D019098:Telomerase / Q000096:biosynthesis* / Q000235:genetics; D013997:Time Factors; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D003470:Culture Media; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D019098:Telomerase; D001616:beta-Galactosidase