Investigation into the signal transduction pathway via which heat stress impairs intestinal epithelial barrier function.
OBJECTIVE
Intact protein absorption is thought to be a causative factor in several intestinal diseases, such as food allergy, celiac disease and inflammatory bowel disease. However, the mechanism remains unclear. The aim of this study was to characterize a novel signal transduction pathway via which heat stress compromises intestinal epithelial barrier function.


METHODS
Heat stress was carried out by exposing confluent human intestinal epithelial cell line T84 cell monolayers to designated temperatures (37-43 degrees C) for 1 h. Transepithelial electric resistance (TER) and permeability to horseradish peroxidase (HRP, molecular weight = 44 000) were used as indicators to assess the intestinal epithelial barrier function. Phosphorylated myosin light chain (MLC), MLC kinase (MLCK) and protein kinase C (PKC) protein of the T84 cells were evaluated in order to identify the signal transduction pathway in the course of heat stress-induced intestinal epithelial barrier dysfunctions.


RESULTS
The results showed that exposure to heat stress significantly increased intact protein transport across the intestinal epithelial monolayer; the amount of phospho-PKC, phospho-MLCK and phospho-MLC proteins in T84 cells decreased significantly at 41 degrees C and 43 degrees C although they increased at 39 degrees C. The heat stress-induced T84 monolayer barrier dysfunction was inhibited by pretreatment with PKC inhibitor, MLCK inhibitor, or HSP70.


CONCLUSIONS
Heat stress can induce intestinal epithelial barrier dysfunction via the PKC and MLC signal transduction pathway.
Yang
Ping-Chang
PC
Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada. yangp@mcmaster.ca
He
Shao-Heng
SH
Zheng
Peng-Yuan
PY
D000222:Adaptation, Physiological; D001381:Azepines / Q000494:pharmacology; D002460:Cell Line; D017097:Electric Impedance; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000503:physiopathology; D018994:Myosin Light Chains / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009281:Naphthalenes / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D010539:Permeability; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000201:enzymology / Q000378:metabolism* / Q000503:physiopathology; D013997:Time Factors
D001381:Azepines; D018840:HSP70 Heat-Shock Proteins; D018994:Myosin Light Chains; D009281:Naphthalenes; D009842:Oligopeptides; D047428:Protein Kinase Inhibitors; D011506:Proteins; C070571:ML 7; D006735:Horseradish Peroxidase; D011493:Protein Kinase C; D009219:Myosin-Light-Chain Kinase