Limited heat-shock protein 72 induction in Caco-2 cells by L-glutamine

Background/Aims: L-Glutamine (L-gin) is a conditionally essential amino aci d which is consumed by certain tissues like the intestine in large amounts as energy source during critical illness. Apart from nutritive action, rece nt data suggest a link to heat-shock protein (hsp) induction. We investigat ed the effect of L-gln on hsp72 expression in the intestinal cell line Caco -2 under basal and heat-shock conditions and compared it with related amino acids. Methods: Total cellular protein was extracted and separated by SDS- PAGE. Immunoblots were performed with anti-hsp72 followed by chemiluminesce nce detection and densitometric scanning. Results: Following heat shock, hs p72 protein expression increased by 72 and 53% at 2 and 4 mmol/l L-gln, res pectively, compared to heat shock alone (p < 0.05). Under basal conditions a limited increase occurred only at 8 mmol/l L-gln (p < 0.01), Levels remai ned unaffected when related amino acids including alanine, glutamate or gly cine were supplemented under basal and heat-shock conditions. Similarly,the nonmetabolizable glutamine analogue DON or the toxic metabolite L-pyroglut amate did not induce hsp72. Conclusion: We conclude that the glutamine-medi ated effect may be specifically attributed to the metabolic action of L-gln . Copyright (C) 2001 S. Karger AG, Basel.