Glutamine Regulates the Human Epithelial Intestinal HCT-8 Cell Proteome under Apoptotic Conditions

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-␣-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 mod-

Glutamine metabolism in advanced age

“…Cytosolic glutamine synthetase, which is a longevityrelated gene, is responsible for this synthesis Small intestine and kidneys are the major sites of glutamine utilization under normal or acidotic conditions Intracellular glutamine concentration generally decreases in catabolic states. In humans, this change can be prevented or attenuated by glutamine supplementation (enteral or parenteral) The liver can synthesize or degrade glutamine, depending on the nutritional conditions (2)Regulatory roles of glutamine in cell-specific processes Boukhettala et al (2012), 25 Brasse-Lagnel et al (2009), 26 Yi et al (2015) 27 , BrasseLagnel (2010), 28 Curi et al (2005) 29 (2007), 30 Deniel et al (2007), 31 Larson 34 Matés et al (2006), 37 Nakajo et al (2005), 38 Naomoto et al (2005), 39 Nishikawa et al (2007), 40 Papaconstantinou (2000), 41 Rhoads & Wu (2009), 42 Roth et al (2002), 45 Roth (2007), 43 (2008), 44 Rutten et al Abbreviations: ATP, adenosine triphosphate; EAAs, essential amino acids; NEAAs, nonessential amino acids; NF-jB, nuclear factor jB.…”

“…Whereas glutamine upregulates anti-apoptotic proteins and downregulates pro-apoptotic proteins in T cells, it prevents apoptosis in rat epithelial cell lines derived from gut mucosa; moreover, glutamine starvation induces apoptosis through caspase activation. 31,35 In brief, glutamine may play a role in the gut-protective effect by inhibiting apoptosis via downregulation of the transcription factor Sp3, by contributing to cell survival during physiological stress by induction of autophagy, by modulating intestinal barrier function under basal and inflammatory conditions, or by its anti-inflammatory effect via induction of nuclear degradation of the NF-jB p65 subunit. 59,60 Glutamine is a key regulator of amino acidcontrolled cell growth through the mammalian target of rapamycin (mTOR) signaling pathway in rat intestinal epithelial cells.…”

“…59,60 Glutamine is a key regulator of amino acidcontrolled cell growth through the mammalian target of rapamycin (mTOR) signaling pathway in rat intestinal epithelial cells. 27,28,31,39,42,61,62 Amino acids are important signaling regulators, especially for p70 S6 kinase and eIF-4E binding protein 1 via mTOR, which have 2 structurally and functionally distinct complexes termed mTORC1 and mTORC2. mTORC1 is activated by nutrients (amino acids), growth factors, and cellular energy, while mTORC2 is activated by growth factors alone.…”

Glutamine protects against apoptosis via downregulation of Sp3 in intestinal epithelial cells

“…Glutamine in commercially available enteral formulas is ϳ60 mM and, when used as an isolated nutrient, can be as high as 500 mM. However, in the present study, the effects of 2 mM (basal concentration, as control) and 10 mM glutamine on IEC-6 cells were compared on the basis of previous studies that suggested that 2 mM and 10 mM glutamine cover the range of physiological and pharmacological concentrations in intestinal cells (12,35,36).…”

Protective effect of <i>N</i>-acetylcysteine against nicardipine hydrochloride-induced autophagic cell death of human vascular endothelial cells

“…Asn selectively inhibited autophagic lysosomal delivery (Høyvik et al, 1991). Gln ameliorated autophagic cell death via modulation of ATG5 protein (Deniel et al, 2007). Thus, inhibition of autophagic lysosomal delivery with Asn and modulation of ATG5 protein with Asn could not ameliorate NIC-induced cell injury.…”