Activation of covalent affinity labeled glucocorticoid receptor-steroid complexes

S. S. Simons, R. E. Schleenbaker, H. J. Eisen

Research output: Contribution to journalArticlepeer-review

71 Scopus citations

Abstract

Dexamethasone 21-mesylate is an irreversible anti-glucocorticoid in rat hepatoma tissue culture (HTC) cells and can affinity label the glucocorticoid receptor in cell-free systems. We now report that dexamethasone 21-mesylate also labels glucocorticoid receptors in intact HTC cells. As a first step toward understanding the whole cell antiglucocorticoid effects of dexamethasone 21-mesylate, we have examined the ability of cell-free covalent rat liver and HTC cell receptor-steroid complexes to undergo activation to forms that bind to DNA-cellulose. After optimization of the covalent labeling conditions, greater than 90% of the available glucocorticoid receptors could be labeled covalently with [3H]dexamethasone 21-mesylate. Under conditions of ~70% labeling efficiency, those covalently labeled receptor complexes that had been subjected to activating conditions were found to bind to DNA-cellulose. Little binding of covalent complexes to DNA-cellulose occurred in the absence of activation. The ability of covalently labeled receptors to be activated to the DNA-binding state has been used to prepare labeled receptors that are almost radiochemically pure. The molecular weights of unactivated or activated rat liver on HTC cell receptors labeled by [3H]dexamethasone 21-mesylate in cell-free systems or in whole cells with or without protease inhibitors were indistinguishable by NaDodSO4-polyacrylamide gel electrophoresis (M(r)=89,000 ± 3,000). As judged by the efficiency of activation and the NaCl elution profile of DNA cellulose-bound complexes, no significant differences could be detected between the cell-free activated forms of covalent dexamethasone 21-mesylate and noncovalent dexamethasone 21-mesylate-labeled receptors in whole HTC cells, as defined by nuclear binding, was much less efficient both than that seen under cell-free conditions and than that seen for dexamethasone-labeled receptors in whole cells.

Original languageEnglish
Pages (from-to)2229-2238
Number of pages10
JournalJournal of Biological Chemistry
Volume258
Issue number4
StatePublished - 1983

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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