Glucocorticoid regulation of glycosaminoglycan synthesis in cultured human skin fibroblasts: evidence for a receptor-mediated mechanism involving effects on specific de novo protein synthesis.
Human skin fibroblast cultures synthesize and accumulate glycosaminoglycan (GAG). This laboratory has reported recently that the synthetic rate of hyaluronate (HA), the most abundant GAG produced by these cells, is inhibited by glucocorticoids. The purpose of these studies was to characterize further that hormonal response. Effects of potent glucocorticoid agonists dexamethasone (Dex) and RU28362 on GAG synthesis were studied. Both steroids inhibited [3H]GAG synthesis when added 24 hours before labeling with [3H]acetate. RU28362 inhibited HA synthesis by 58% and Dex by 60%. The half-maximal effect for each was achieved at a concentration of 0.5 nmol/L and maximal effects at 10 nmol/L. The recently described glucocorticoid antagonist RU38486 failed to alter [3H]GAG synthesis at concentrations up to 1,000 nmol/L. However, this compound did block the inhibition of the agonists. At concentrations of RU28362 and Dex that maximally inhibited [3H]GAG synthesis (10 nmol/L), RU38486 attenuated the glucocorticoid effect in a dose-dependent manner, with half-maximal inhibition at 5 nmol/L and maximal inhibition at 100 nmol/L. The antagonist blocked as much as approximately 80% of the Dex inhibition and approximately 70% of the RU28362 inhibition. Cycloheximide (25 micrograms/mL) inhibited [3H]HA synthesis by 55% within four hours of its addition to the culture. When cultures were pretreated with cycloheximide without or with Dex (100 nmol/L) for three hours and then treated with actinomycin D (2 micrograms/mL) followed by [3H]acetate labeling, Dex pretreated cultures synthesized 33% less [3H]GAG, implying that Dex had decreased the abundance of a translatable mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)
Smith
T J
TJ
Endocrine Sections, Veterans Administration Medical Center, Augusta, GA.
D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D005938:Glucocorticoids / Q000494:pharmacology*; D006025:Glycosaminoglycans / Q000096:biosynthesis*; D006801:Humans; D006820:Hyaluronic Acid / Q000096:biosynthesis; D014176:Protein Biosynthesis; D011965:Receptors, Glucocorticoid / Q000502:physiology*
D005938:Glucocorticoids; D006025:Glycosaminoglycans; D011965:Receptors, Glucocorticoid; D006820:Hyaluronic Acid; D003513:Cycloheximide