title: Expression of platelet-derived growth factor-beta receptors on human fibroblasts. Regulation by recombinant platelet-derived growth factor-BB, IL-1, and tumor necrosis factor-alpha.
abstract: Stimulation of human fibroblasts by platelet-derived growth factor (PDGF)-BB leads to a down-regulation of PDGF beta-receptors and a concomitant appearance of intracellular granular accumulations of receptors, as determined by stainings with the mAb PDGFR-B2. The granules contained both the ligand and PDGF beta-receptors, as revealed by double-immunofluorescence staining, and were formed in response to PDGF-BB but not in response to other cytokines tested. The formation of intracellular PDGF beta-receptor granules was dependent on PDGF-BB concentration and time of stimulation. The granular PDGF beta-receptor staining on cells treated with PDGF-BB for 1 h at 37 degrees C was used to investigate the effects of macrophage-derived cytokines on PDGF beta-receptor expression. The number of PDGF beta-receptor granules was found to be reduced in fibroblasts grown for 48 h in the presence of PDGF-BB, TNF-alpha, or IL-1; PDGF-AA under the same conditions had no effect. The reduction observed was paralleled by a decrease in cell surface expression of PDGF beta-receptors, measured as binding of 125I-PDGF-BB and of the PDGFR-B2 antibody. Furthermore, both TNF-alpha and IL-1 decreased the detergent-extractable pool of PDGF-beta receptors in the fibroblasts, as revealed by immunoblotting of detergent cell extracts. Finally, the decrease in PDGF beta-receptors after culturing of the cells in the presence of TNF-alpha and IL-1 was accompanied by a decreased incorporation of [3H]thymidine in response to PDGF-BB stimulation. In conclusion, our data suggest that certain macrophage-derived cytokines can modulate the expression of PDGF beta-receptors by cultured fibroblasts, which may contribute in part to their reduced responsiveness to PDGF.
authors.affiliation: Department of Medical and Physiological Chemistry, University of Uppsala, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Tingström
authors.forename: C
authors.initials: C
authors.lastname: Reuterdahl
authors.forename: P
authors.initials: P
authors.lastname: Lindahl
authors.forename: C H
authors.initials: CH
authors.lastname: Heldin
authors.forename: K
authors.initials: K
authors.lastname: Rubin
mesh_terms: D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D015536:Down-Regulation; D005347:Fibroblasts / Q000737:chemistry; D006801:Humans; D007124:Immunoenzyme Techniques; D007375:Interleukin-1 / Q000494:pharmacology*; D017830:Octoxynol; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000032:analysis*; D017479:Receptors, Platelet-Derived Growth Factor; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D007375:Interleukin-1; D010982:Platelet-Derived Growth Factor; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D011092:Polyethylene Glycols; D017830:Octoxynol; D004247:DNA; D017479:Receptors, Platelet-Derived Growth Factor