Abstract
Glutamine plays a key role in the metabolism of rapidly dividing cells, including enterocytes and lymphocytes, which may contribute to its beneficial clinical effects. Gut mucosal homeostasis is achieved through a balance between cell proliferation and apoptosis. In T cells, glutamine up-regulates antiapoptotic proteins and down-regulates proapoptotic proteins. In gut mucosa, glutamine prevents apoptosis in rat epithelial cell lines, whereas glutamine starvation induces apoptosis through caspase activation. Finally glutamine specifically prevents tumor necrosis factor-alpha-related apoptosis in the human intestinal cell line HT-29. Comparative functional proteomics enables the characterization of each differentially expressed protein in intestinal cells in response to modifications of nutritional environment. The influence of glutamine on intestinal proteome expression in apoptotic conditions has not been studied and evaluated. This comparative proteomics study was performed in the human epithelial intestinal cell line HCT-8 under experimental apoptotic conditions to investigate the influence of glutamine on protein expression during apoptosis. The pharmaconutritional effects of glutamine were determined under 2 mm (physiological concentration) and 10 mm (pharmaconutritional concentration) conditions. About 1,800 protein spots were revealed in both conditions. Comparative assessments indicated that 28 proteins were differentially expressed significantly (i.e. at least 2-fold modulated and Student's t test with p </= 0.05) in response to an increase of glutamine concentration in the culture medium. Twenty-four proteins were identified by mass spectrometry and associated databases. From these proteins, 34% are involved in cell cycle and apoptosis mechanisms, 17% are involved in signal transduction, and 13% are involved in cytoskeleton organization. These data were integrated in a proposed schema of the interactome under apoptotic conditions. In conclusion, this study provides the first holistic picture of proteome modulation by glutamine in a human enterocytic cell line under apoptotic conditions and supports further evaluation of nutritional modulation of human intestinal proteome in various pathological conditions where apoptosis may be involved.
Highlights
Glutamine plays a key role in the metabolism of rapidly dividing cells, including enterocytes and lymphocytes, which may contribute to its beneficial clinical effects
Gut mucosal homeostasis is achieved through a balance between cell proliferation, located in the crypt of Lieberkuhn, and cell elimination by apoptosis, predominantly localized in both the crypt and villus compartment [7]
Gln-induced Effects on the Apoptotic HCT-8 Cell Proteome—Approximately 1,800 protein spots per gel were detected within a pI range of 3–10 and a relative molecular mass range of 10 –150 kDa. 2-D gels obtained from cells exposed under apoptotic conditions in medium containing 2 or 10 mM Gln are presented in Fig. 1, A and B
Summary
Glutamine plays a key role in the metabolism of rapidly dividing cells, including enterocytes and lymphocytes, which may contribute to its beneficial clinical effects. This study was designed to provide a holistic picture of protein modulations in Gln-treated (Gln concentration at 2 and 10 mM) human intestinal epithelial HCT-8 cells under CH11-induced apoptotic conditions.
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