Depletion of tryptophan is not involved in expression of tryptophanyl-tRNA synthetase mediated by interferon

Abstract

Gamma interferon (IFN-γ) affects tryptophan metabolism by mediating the expression of indoleamine 2,3-dioxygenase and tryptophanyl-tRNA synthetase. In the present study, we investigated the role of indoleamine 2,3- dioxygenase-mediated tryptophan depletion in the induction of tryptophanyl- tRNA synthetase by IFN-γ. The addition of excess tryptophan to the culture medium did not affect the induction of tryptophanyl-tRNA synthetase by IFN- γ, indicating that tryptophan degradation is not directly involved in the IFN-γ-mediated expression of tryptophanyl-tRNA synthetase.