Evidence for more than one mechanism of action of the glucocorticoid hormones.
The data presented here provide evidence for at least two major cellular responses to the glucocorticoid hormones that do not seem to involve an interaction between the activated hormone-receptor complex and chromatin. We observed that 5mM pyridoxine in L-cell culture medium both increases the intracellular content of free pyridoxal phosphate by about 30% and decreases the glucocorticoid induction of glutamine synthetase to less than 30% of that at the normal (5 microM) concentration of the vitamin. Two other responses to the hormone-a major decrease in the polysome content of the cells and a decrease in the state of phosphorylation of ribosomal protein S6-are unaffected by the 5mM dose of the vitamin. In light of the findings of DiSorbo and Litwack ((1981) Biochem. Biophys. Res. Commun. 99, 1203-1208), pyridoxal phosphate appears to modulate the enzyme-inducing activity of dexamethasone in L-cells but not the polysome and ribosome related changes. These results are consistent with the hypothesis that certain important glucocorticoid induced responses are independent of nuclear function.
D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology*; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D007700:Kinetics; D007739:L Cells / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D010766:Phosphorylation; D011132:Polyribosomes / Q000187:drug effects / Q000378:metabolism; D011732:Pyridoxal Phosphate / Q000378:metabolism; D011736:Pyridoxine / Q000494:pharmacology; D012269:Ribosomal Proteins / Q000378:metabolism
D012269:Ribosomal Proteins; D011732:Pyridoxal Phosphate; D003907:Dexamethasone; D005974:Glutamate-Ammonia Ligase; D011736:Pyridoxine