Role of phospholipase Cγ-induced activation of protein kinase C ε (PKCε) and PKCβI in epidermal growth factor-mediated protection of tight junctions from acetaldehyde in caco-2 cell monolayers

Epidermal growth factor (EGF) protects the intestinal epithelial tight junctions from acetaldehyde-induced insult. The role of phospholipase C gamma (PLC gamma) and protein kinase C (PKC) iso-forms in the mechanism of EGF-mediated protection of tight junction from acetaldehyde was evaluated in Caco-2 cell monolayers. EGF-mediated prevention of acetaldehyde-induced decrease in transepithelial electrical resistance and an increase in inulin permeability, and subcellular redistribution of occludin and ZO-1 was attenuated by reduced expression of PLC gamma 1 by short hairpin RNA. EGF induced a rapid activation of PLC gamma 1 and PLC-dependent membrane translocation of PKC epsilon and PKC alpha I. Inhibition of PKC activity or selective interference of membrane translocation of PKC epsilon andPKC beta I by RACK interference peptides attenuated EGF-mediated prevention of acetaldehyde-induced increase in inulin permeability and redistribution of occludin and ZO-1. BAPTA-AM and thapsigargin blocked EGF-induced membrane translocation of PKC beta I and attenuated EGF-mediated prevention of acetaldehyde-induced disruption of tight junctions. EGF-induced translocation of PKC epsilon and PKC beta I was associated with organization of F-actin near the perijunctional region. This study shows that PLC gamma-mediated activation of PKC epsilon and PKC beta I and intracellular calcium is involved in EGF-mediated protection of tight junctions from acetaldehyde-induced insult.