Title: Triamcinolone Acetonide Destabilizes VEGF mRNA in Müller Cells under Continuous Cobalt Stimulation
Abstract: To identify the molecular mechanism of steroid-induced downregulation of vascular endothelial growth factor (VEGF) synthesis in Müller cells.Confluent cultures of human Müller cells (MIO-M1) were treated with 100 microM CoCl(2), 1 microg/mL triamcinolone acetonide (TA), or both. VEGF secretion was measured with respect to time by ELISA. VEGF mRNA quantity and stability were analyzed by reverse transcriptase-polymerase chain reaction. The activity of hypoxia-inducible factor (HIF)-1 was measured by the relative binding of HIF-1 protein to the hypoxia response element (HRE), by gel shift and ELISA. The HIF-1alpha protein level was determined with Western blot.TA decreased VEGF secretion by at least 50% in the presence of continuous cobalt stimulus. VEGF mRNA decreased 50- to 100-fold 6 hours after treatment with TA and cobalt compared with cobalt alone. VEGF mRNA stability was decreased in cobalt-stimulated, TA-treated cells compared with cobalt alone in cells synchronized by exposure to actinomycin D. HIF-1alpha protein level was sustained for the entire 24-hour treatment period and partitioned into nuclear, not cytosolic, fractions. HIF-1 activity was decreased by 20% to 30% in the presence of TA and cobalt compared with cobalt alone.TA may decrease VEGF synthesis by nongenomic destabilization of VEGF mRNA in cobalt-stimulated Müller cells. There was little effect on the total HIF-1alpha protein level, HIF-1 partitioning, and HIF-1 activity.
Publication Year: 2005
Publication Date: 2005-11-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 55
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