In vivo and in vitro effect of glucocorticoids on fibroblast growth factor (FGF)-2 and FGF receptor 1 expression.
In order to clarify the physiological function of fibroblast growth factor (FGF-2) in the adrenal medulla the regulation of FGF-2 and FGF receptor 1 (FGFR1) was studied in vitro and in vivo in response to glucocorticoids. To assess the effects of glucocorticoids, in vivo extracts of adrenal medulla and adrenal cortex were analyzed by RNase protection assay and Western blot analysis. PC12 cells were chosen as a model system to study the effects of glucocorticoids in vitro. In PC12 cells, dexamethasone (DEX) was found to stimulate dramatically the expression of both FGF-2 mRNA and protein. Western blot analysis revealed that exclusively the 21-kDa FGF-2 isoform was enhanced. In contrast to the FGF-2 mRNA level FGFR1 was not affected by treatment with glucocorticoids. In vivo FGF-2 mRNA level and 21-kDa FGF-2 isoform level are significantly enhanced in the adrenal medulla 24 h after DEX injection. In vivo application of DEX leads to an increase of the medullary and cortical FGFR1 transcript levels. Glucocorticoid effects on FGF-2 expression were not found in adrenal cortex, heart, skeletal muscle, and kidney, respectively, in vivo and in L6 rat myoblasts in vitro. In addition to adrenal medullary cells glucocorticoids elevated the FGF-2 mRNA and protein level also in vivo in the brain and in vitro in immortalized Schwann cells. The present results suggest that the 21-kDa FGF-2 isoform mediates a physiological function specific for neuronal tissue which is modulated by glucocorticoids.
Meisinger
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Institute of Anatomy, University of Freiburg, D-79104 Freiburg, Federal Republic of Germany.
Zeschnigk
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Grothe
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D000302:Adrenal Cortex / Q000378:metabolism; D000313:Adrenal Medulla / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D005346:Fibroblast Growth Factors / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects*; D007668:Kidney / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D016716:PC12 Cells; D016548:Prosencephalon / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D051496:Receptor, Fibroblast Growth Factor, Type 1; D051497:Receptor, Fibroblast Growth Factor, Type 2; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics* / Q000378:metabolism
D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; D005346:Fibroblast Growth Factors; D003907:Dexamethasone; C496350:Fgfr1 protein, rat; C496356:Fgfr2 protein, rat; D020794:Receptor Protein-Tyrosine Kinases; D051496:Receptor, Fibroblast Growth Factor, Type 1; D051497:Receptor, Fibroblast Growth Factor, Type 2