An Investigation of the Expression of Thrombomodulin in Cultured Human Umbilical Vein Endothelial Cells

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We investigated the expression of thrombomodulin in cultured human umbilical vein endothelial cells(HUVEC) and human megakaryoblastic leukemia cell line, MEG-01 and got the following results.1) An incubation of the cell swith 3-5 mM dbcAMP upregulated the expression of cellsurface throbomodulin. The cell-surface TM was increased by aproximately by 250 % in HUVEC and by 600 % in MEG-01.2) The other agents such as IBMX, forskolin, prostacyclin, which increase in intracellular cAMP, also increase in the cell-surface thrombomodulin.3) IL-1 and TNF alpha, however, decreased in the cell-surface thrombomodulin by about 50 %.4) We could not find so called cAMP responsive element in the upstream of thrombomodulin genome.5) Two type of thrombomodulin is expressed in CHO cells which constructed by the transfection of human thrombomodulin cDNA. A thrombomodulin with a molecular weight of 75, 000 dalton has been recognized as thrombomodulin. Another thrombomdulin with the 170, 000 dalton is expressed and designated as type 2 thrombomodulin. CHO cells expressed both type of thrombomodulin by equal amount.6) The expression ratio of two type of thrombomodulin was examined by immunoblotting. HUVEC in normal culture expressed type two thrombomodulin about 5 %.