Enterotoxigenic Escherichia coli infection induces tight junction proteins expression in mice

Enterotoxigenic Escherichia coli (ETEC) causes diarrhea in travelers, young children and piglets, but the precise pathogenesis of ETEC induced diarrhea is not fully known. Recent investigations have shown that tight junction (TJ) proteins and aquaporin 3 (AQP 3) are contributing factors in bacterial diarrhea. In this study, using immunoblotting and immunohistochemistry analyses, we found that ETEC increases the protein abundance of TJ proteins (occludin, claudin-1, zonula occludens-1) in mice. Enterotoxigenic Escherichia coli induced the expression of TJ proteins in mice through pathways by involving myosin light chain kinase (MLCK)-myosin II regulatory light chain (MLC20) pathways; however, ETEC has little effect on the activation of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway. Enterotoxigenic Escherichia coli infection has little effect on the protein abundance of AQP 3. Collectively, ETEC infection affects the abundance of intestinal TJ protein, which suggests the importance of TJ proteins in ETEC induced diarrhea.