CHANGES IN THE CELLULAR-DISTRIBUTION OF LIPOCORTIN-1 (ANNEXIN-1) IN C6 GLIOMA-CELLS AFTER EXPOSURE TO DEXAMETHASONE

Glucocorticoid-induced changes in cellular levels of Lipocortin-l (LC-1) (Annexin 1) in C6 glioma cells were determined by electrotransfer and immunoblotting techniques. Separate cell protein fractions were prepared to study the influence of the glucocorticoid steroid, dexamethasone, on LC-1 localisation. Cells were grown in steroid-depleted medium and exposed to dexamethasone (10(-8) and 10(-7) M) for 2, 6, and 16 hr. The glucocorticoid-dependent changes in cellular content of LC-I were both dose- and time-related. Increases above control levels in intracellular and extracellular LC-I content were detected with the greatest changes occurring at the cell surface. The glucocorticoid-dependent alteration in LC-I distribution in C6 glioma cells was attenuated by the protein synthesis inhibitor, cycloheximide, indicating the involvement of de novo LC-1 synthesis. The significance of these results is discussed in relation to the current concept that some of the anti-inflammatory effect of glucocorticoids occurs through the action of extracellular LC-1.