Regulation of PGE2and PGI2release from human umbilical vein endothelial cells by actin cytoskeleton

Abstract

Disruption of microfilaments in human umbilical vein endothelial cells (HUVEC) with cytochalasin D (cytD) or latrunculin A (latA) resulted in a 3.3- to 5.7-fold increase in total synthesis of prostaglandin E2(PGE2) and a 3.4- to 6.5-fold increase in prostacyclin (PGI2) compared with control cells. Disruption of the microtubule network with nocodazole or colchicine increased synthesis of PGE21.7- to 1.9-fold and PGI21.9- to 2.0-fold compared with control cells. Interestingly, however, increased release of PGE2and PGI2from HUVEC into the media occurred only when microfilaments were disrupted. CytD treatment resulted in 6.7-fold more PGE2and 3.8-fold more PGI2released from HUVEC compared with control cells; latA treatment resulted in 17.7-fold more PGE2and 11.2-fold more PGI2released compared with control cells. Both increased synthesis and release of prostaglandins in response to all drug treatments were completely inhibited by NS-398, a specific inhibitor of cyclooxygenase-2 (COX-2). Disruption of either microfilaments using cytD or latA or of microtubules using nocodazole or colchicine resulted in a significant increase in COX-2 protein levels, suggesting that the increased synthesis of prostaglandins in response to drug treatments may result from increased activity of COX-2. These results, together with studies demonstrating a vasoprotective role for prostaglandins, suggest that the cytoskeleton plays an important role in maintenance of endothelial barrier function by regulating prostaglandin synthesis and release from HUVEC.