Rapid induction of the intrinsic apoptotic pathway by L‐glutamine starvation

Abstract

While the amino acid L‐glutamine is known to play a role in the survival of several cell types, the underlying molecular mechanisms are still poorly defined. We show in this report that L‐glutamine starvation rapidly triggered apoptosis in Sp2/0‐Ag14 hybridoma cells. This process involved the activation of both caspases‐9 and ‐3, suggesting that L‐glutamine deprivation initiated an intrinsic apoptotic pathway in Sp2/0‐Ag14 cells. Supporting this idea, the cytosolic release of the mitochondrial proteins SMAC/DIABLO and cytochrome c (Cyt c) was observed, with an initial limited leakage occurring during the first 30 min of L‐glutamine deprivation, followed by a greater release after 60 min. The latter occurred simultaneously with the translocation of the pro‐apoptotic protein Bax to the mitochondria. Finally, a decline in XIAP levels and the activation of caspases‐3 and ‐9 were observed. Thus, L‐glutamine deprivation of Sp2/0‐Ag14 cells rapidly triggers intracellular events, which target the mitochondria, leading to the cytosolic release of apoptogenic factors, the activation of caspases‐9 and ‐3, and the commitment to the death program. This work introduces the Sp2/0Ag14 hybridoma as a unique model for the study of the molecular events underlying the pro‐survival function of L‐glutamine.