PTK6 Contributes to TNFα‐induced Intestinal Epithelial Barrier Dysfunction

Abstract

Intestinal epithelial barrier dysfunction plays an important role in the development of multiple organ failure during systemic inflammation. The opening of the epithelial barrier leads to increased leukocyte infiltration into the lamina propria, the event therefore promotes microbial translocation and augments intestinal inflammation that contribute to the severity of trauma-associated complications. The aim of the study was to explore the roles of protein kinase 6 (PTK6) and focal adhesion kinase (FAK) in the intestinal epithelial barrier dysfunction following the treatment of TNFα/IFNγ. Epithelial barrier function was analyzed by measuring transcellular electrical resistance (TER) in cultured mouse intestinal epithelial cells. Our data revealed that stimulation of the epithelial cells with TNFα/IFNγ caused a decrease in transcellular electric resistance coupled with decrease expression of cell junctional proteins. The responses were prevented by the inhibitions of either PTK6 or FAK. Western blot analysis showed that elevated levels of active PTK6 and decreased detection of the tight junction protein claudin-3 upon TNFα stimulation. In addition, the downregulation of PTK6 in cells with siRNA attenuates TNFα/IFNγ induced FAK activation via diminished detection of FAK phosphorylation at Y397. Transfection of PTK6-deficient cells with active PTK6 rescued the FAK activation resulting in epithelial barrier dysfunction in response to TNFα/IFNγ. The results suggest that PTK6 mediated FAK activation plays a critical role in gut epithelial barrier dysfunction during inflammatory injury.