Pathways from glutamine to apoptosis.

It is fascinating that a relatively simple amino acid like glutamine is involved in such large variety of cellular reactions. Glutamine is required for nitrogen-stimulated proliferation in many cells, but glutamine stimulates not only the growth of cells but also the expression of surface antigens, the formation of cytokines, the synthesis of heat shock proteins and many more vital events. Among all of them, apoptosis is a recent but outstanding incorporation to the whole of phenomena regulated by this peculiar amino acid. Apoptosis is an important process in a wide number of biologic systems. Apoptotic signalling mechanisms implicated in response to glutamine deprivation are cell type-specific. In any case, new findings indicate that glutamine availability is strongly related to the induction of apoptosis, working both as a nutrient and as a signalling molecule, acting directly or indirectly on the pathways leading to programmed cell death. Following, we will describe as glutamine and the related species glutamate, glutathione and glucosamine can play important roles in the pathways leading to apoptosis.