12(S)-HETE-induced microvascular endothelial cell retraction results from PKC-dependent rearrangement of cytoskeletal elements and αVβ3 integrins

12(S)-HETE, a lipoxygenase metabolite of arachidonic acid, has been demonstrated to induce a reversible retraction of vascular endothelial cells (EC). 12(S)-HETE-induced microvascular EC retraction was blocked by a selective protein kinase C inhibitor, calphostin C, but not by the protein kinase A inhibitor, H8. EC exposed to 12(S)-HETE demonstrated a gradual dissolution of actin microfilaments and a decrease of vinculin-containing focal adhesions. The intermediate filaments, vimentin, also underwent extensive reorganization (i.e., filament bundling and enrichment to the cell filapodia) following 12(S)-HETE treatment. In vivo phosphorylation studies revealed that 12(S)-HETE induced a hyperphosphorylation of several major cytoskeletal proteins including myosin light chain, actin, and vimentin. The increased phosphorylation of these cytoskeletal proteins following 12(S)-HETE stimulation was abolished by calphostin C but not by H8. Confluent EC express αvβ3 in focal adhesions at both the cell body and the cell-cell borders. 12(S)-HETE induced a sequential rearrangement of the αvβ3-containing focal adhesions, resulting in a general decrease in αvβ3 integrin receptors, especially in those retracted EC. 12(S)-HETE-induced rearrangement of αvβ3 was inhibited by calphostin C but not by H8. In contrast to αvβ3, confluent EC enrich α5β1 integrin receptors primarily at the cell-cell borders, colocalizing with extracellular fibronectin and cell cortical microfilaments. 12(S)-HETE treatment also disrupted the cell-border distribution pattern of α5β1 as EC retracted, but no distinct alterations (such as time-related redistribution and quantitative differences) in α5β1 were observed.