H2O2 AND GENISTEIN DIFFERENTIALLY MODULATE PROTEIN-TYROSINE PHOSPHORYLATION, ENDOTHELIAL MORPHOLOGY, AND MONOLAYER BARRIER FUNCTION

The effects of hydrogen peroxide (H2O2) and the protein tyrosine kinas e (PTK) inhibitor, genistein, to modulate protein tyrosine phosphoryla tion (PTP) and endothelial barrier function were examined in bovine pu lmonary artery endothelial cell (EC) monolayers. H2O2 stimulated a con centration (100-800 mu M) and time-dependent increase in the phosphoty rosine (PY) content elf multiple (56-72, 93-97, 113-142, and 161-183 k Da) EC proteins. A size-selected solute permeability assay of EC monol ayer barrier function showed that (200 mu M) H2O2 elevated EC monolaye r permeability to large solutes. This effect was associated with parac ellular hole formation and a loss of beta-catenin immunostaining at th ese sites. In contrast, genistein (100 mu M, 1 h) reduced basal PY pro tein content and reorganized F-actin to beta-catenin containing cell-c ell junctions, enhancing endothelial monolayer barrier function. In ad dition, genistein prevented the H2O2-induced increases in tyrosine pho sphorylation, monolayer permeability, and paracellular hole formation. These data suggest that H2O2 and genistein differentially regulate PT P, endothelial morphology, and monolayer barrier function. (C) 1998 Ac ademic Press.