Endothelin-1-selective binding sites are downregulated by transforming growth factor-beta and upregulated by basic fibroblast growth factor in a vascular smooth muscle-derived cell line.
Endothelins (ETs) elicit in vivo and in vitro a potent vasoconstrictor activity after binding to high-affinity receptors on vascular smooth muscle cells (VSMC). A617 cells, a VSM-derived cell line, were used as an in vitro model system to study selected growth factors and cytokines involved in proliferative and/or inflammatory diseases of the vessel wall as possible regulators of the high-affinity binding capacity of ET-1 to the cells. Radioligand studies characterized the binding of ET-1 to the isopeptide selective ETA receptor subtype on A617 cells as a time- and temperature-dependent saturable process (Kd = 0.13 +/- 0.04 nM, Bmax = 49 +/- 7 fmol/10(6) cells). Pretreatment of A617 cells with basic fibroblast growth factor (bFGF), a mitogenic agent for vascular cells, resulted in a time- and dose-dependent increase in ET-1 binding capacity, whereas preexposure to transforming growth factor-beta (TGF-beta) induced a reduction of the Bmax for ET-1. Platelet-derived growth factor (PDGF), interleukin-6 (IL-6), tumor necrosis factor-alpha, and fetal bovine serum (FBS) pretreatments did not affect consequent ET-1 binding to A617 cells.
Cristiani
C
C
Pharmacia BioScience Center, Nerviano, Italy.
Volpi
D
D
Landonio
A
A
Bertolero
F
F
D001665:Binding Sites; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects*; D016232:Endothelins / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D007457:Iodine Radioisotopes; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D017466:Receptors, Endothelin / Q000187:drug effects* / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects*
D016207:Cytokines; D016232:Endothelins; D006133:Growth Substances; D007457:Iodine Radioisotopes; D017466:Receptors, Endothelin; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2