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Enteropathogenic Escherichia coli-induced myosin light chain phosphorylation alters intestinal epithelial
R Yuhan1, A Koutsouris, S D Savkovic
1Department of Medicine, University of Illinois, Chicago, USA.
Background & Aims:
Infection of epithelial cells with enteropathogenic Escherichia coli (EPEC) induces phosphorylation of the 20-kilodalton myosin light chain (MLC20). The physiological consequence of this biochemical observation, however, has not been discerned. The aim of this study was to determine if EPEC-induced phosphorylation of MLC20 was involved in the associated perturbation of intestinal epithelial barrier function.
Methods:
Cultured intestinal epithelial cells, T84, were infected with EPEC. The effects of protein kinase inhibitors on EPEC-induced perturbation of barrier function were assessed using electrophysiological techniques. Alterations in MLC20 phosphorylation were correlated with functional responses.
Results:
Inhibition of myosin light chain kinase, but not protein kinase C or tyrosine kinase, prevented the decrease in resistance caused by EPEC infection and significantly diminished EPEC-induced MLC20 phosphorylation. Epithelial cell monolayers genetically manipulated to constitutively increase MLC20 phosphorylation were relatively resistant to the effects of EPEC on barrier function.
Conclusions:
For the first time, these data show that a physiological consequence of the long-recognized increase in MLC20 phosphorylation by EPEC is perturbation of intestinal epithelial barrier function, which probably contributes to the diarrhea associated with this infection.
Insights
Enteropathogenic Escherichia coli (EPEC) infection disrupts intestinal barrier function by increasing myosin light chain 20 (MLC20) phosphorylation. This study confirms MLC20 phosphorylation is key to EPEC-induced barrier dysfunction, contributing to diarrhea.
Area of Science:
- Microbiology
- Cell Biology
- Gastroenterology
Background:
- Enteropathogenic Escherichia coli (EPEC) infection is known to induce phosphorylation of myosin light chain 20 (MLC20) in epithelial cells.
- The physiological impact of EPEC-induced MLC20 phosphorylation on intestinal epithelial barrier function remained unclear.
Purpose of the Study:
- To investigate the role of EPEC-induced MLC20 phosphorylation in the disruption of intestinal epithelial barrier function.
Main Methods:
- T84 intestinal epithelial cells were infected with EPEC.
- Electrophysiological techniques assessed the effects of protein kinase inhibitors on barrier function.
- MLC20 phosphorylation levels were correlated with functional barrier responses.
Main Results:
- Inhibition of myosin light chain kinase, but not other kinases, prevented EPEC-induced barrier dysfunction and reduced MLC20 phosphorylation.
- Cells with constitutively high MLC20 phosphorylation showed resistance to EPEC's effects on barrier function.
Conclusions:
- EPEC-induced MLC20 phosphorylation directly contributes to the perturbation of intestinal epithelial barrier function.
- This mechanism likely plays a significant role in the diarrhea associated with EPEC infections.