Role of glutamine depletion in directing tissue-specific nutrient stress responses to L-asparaginase.

Article Details

Citation

Copy to clipboard

Reinert RB, Oberle LM, Wek SA, Bunpo P, Wang XP, Mileva I, Goodwin LO, Aldrich CJ, Durden DL, McNurlan MA, Wek RC, Anthony TG

Role of glutamine depletion in directing tissue-specific nutrient stress responses to L-asparaginase.

J Biol Chem. 2006 Oct 20;281(42):31222-33. Epub 2006 Aug 24.

PubMed ID

16931516 [ View in PubMed

]

Abstract

L-asparaginase is important in the induction regimen for treating acute lymphoblastic leukemia. Cytotoxic complications are clinically significant problems lacking mechanistic insight. To reveal tissue-specific molecular responses to this drug, mice were administered asparaginase from either Escherichia coli (clinically used) or Wolinella succinogenes (novel, glutaminase-free form). Both enzymes abolished serum asparagine, but only the E. coli form reduced circulating glutamine. E. coli asparaginase reduced protein synthesis in liver and spleen but not pancreas via increased phosphorylation of the translation factor eIF2. In contrast, treatment with Wolinella caused no untoward changes in protein synthesis in any tissue examined. Treating mice deleted for the eIF2 kinase, GCN2, with the E. coli enzyme showed eIF2 phosphorylation to be GCN2-dependent, but only initially. Furthermore, although eIF2 phosphorylation was not increased in the pancreas or by Wolinella asparaginase, expression of the amino acid stress response genes, asparagine synthetase and CHOP/GADD153, increased as a result of both enzymes, even in tissues demonstrating no change in eIF2 phosphorylation. Finally, signaling downstream of the mammalian target of rapamycin kinase was repressed in liver and pancreas by E. coli but not Wolinella asparaginase. These data demonstrate that the nutrient stress response to asparaginase is tissue-specific and exacerbated by glutamine depletion. Importantly, increased expression of asparagine synthetase and CHOP does not require eIF2 phosphorylation, signifying alternate or auxiliary means of inducing gene expression under conditions of amino acid depletion in the whole animal.

DrugBank Data that Cites this Article

Drug Enzymes

Drug	Enzyme	Kind	Organism	Pharmacological Action	Actions
L-Glutamine	Asparagine synthetase [glutamine-hydrolyzing]	Protein	Humans	Unknown	Substrate	Details