Limited heat-shock protein 72 induction in Caco-2 cells by L-glutamine.
OBJECTIVE
L-glutamine (L-gln) is a conditionally essential amino acid which is consumed by certain tissues like the intestine in large amounts as energy source during critical illness. Apart from nutritive action, recent data suggest a link to heat-shock protein (hsp) induction. We investigated 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 chemiluminescence detection and densitometric scanning.


RESULTS
Following heat shock, hsp72 protein expression increased by 72 and 53% at 2 and 4 mmol/l L-gln, respectively, 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 remained unaffected when related amino acids including alanine, glutamate or glycine were supplemented under basal and heat-shock conditions. Similarly, the nonmetabolizable glutamine analogue DON or the toxic metabolite L-pyroglutamate did not induce hsp72.


CONCLUSIONS
We conclude that the glutamine-mediated effect may be specifically attributed to the metabolic action of L-gln.
Lindemann
G
G
Department of Internal Medicine I, Division of Gastroenterology, Medical University of Lübeck, Germany.
Grohs
M
M
Stange
E F
EF
Fellermann
K
K
D000409:Alanine / Q000235:genetics / Q000494:pharmacology; D015153:Blotting, Western; D018938:Caco-2 Cells / Q000187:drug effects* / Q000502:physiology*; D003720:Densitometry; D004591:Electrophoresis, Polyacrylamide Gel; D018698:Glutamic Acid / Q000235:genetics / Q000494:pharmacology; D005973:Glutamine / Q000235:genetics* / Q000494:pharmacology*; D005998:Glycine / Q000235:genetics / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000187:drug effects* / Q000235:genetics*; D006358:Hot Temperature; D006801:Humans; D066298:In Vitro Techniques; D008163:Luminescent Measurements; D011761:Pyrrolidonecarboxylic Acid / Q000494:pharmacology
D006360:Heat-Shock Proteins; D005973:Glutamine; D018698:Glutamic Acid; D000409:Alanine; D011761:Pyrrolidonecarboxylic Acid; D005998:Glycine