Intracellular Mechanisms Responsible for Trypsin-induced Increase in Transepithelial Resistance in Intestinal Epithelial Cells
Date
2013-01-25
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Abstract
Apical addition of serine proteases like trypsin to intestinal epithelial cell
monolayers causes an increase in transepithelial resistance (RTE); however, the
underlying mechanism is unknown. One way that proteases regulate cell function is by
cleaving and activating the Protease Activated Receptor (PAR) family of G-proteincoupled
receptors. In addition, trypsin has been shown to transactivate the epidermal
growth factor receptor (EGFR) via activation of PAR2. Others have shown that activation
of EGFR results in increased RTE in epithelial cells. Hence, we hypothesized that trypsin
increases RTE by activating PARs and/or transactivating EGFR. Apical addition of trypsin
caused a 300% increase in RTE. However, desensitization of PARs-1, 2 and 4 did not
significantly affect the trypsin-induced ΔRTE. PD153035 or AG879 caused a significant
dose-dependent decrease in trypsin-induced ΔRTE via inhibition of EGFR or ErBb2
tyrosine kinase respectively. Anti-transforming growth factor-α antibody reduced trypsininduced
ΔRTE. The trypsin-induced ΔRTE was also reduced by the ERK-1/2 kinase
inhibitor or PI3-kinase inhibitor but was not affected by Src-kinase inhibitor. The trypsininduced
reduction in flux of FITC-dextran was prevented when cells were pre-treated
with PD153035 or AG879. Our data suggest that trypsin increases RTE via transactivation
of EGFR and ErbB2 independently of PAR activation. The trypsin induced RTE partially
depends upon the activation of MAPK and PI3 kinase but not Src-kinase.
Serine proteases may strengthen the epithelial barrier to enhance the efficiency of
electrolyte, water and nutrient transport and may represent a method of countering barrier
deficiencies associated with intestinal disorders.
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Keywords
Animal Physiology, Biology--Molecular, Physiology, Biology--Molecular
Citation
Wadhwani, A. (2013). Intracellular Mechanisms Responsible for Trypsin-induced Increase in Transepithelial Resistance in Intestinal Epithelial Cells (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/26622