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Regulatory mechanisms for thrombomodulin expression in human umbilical vein endothelial cells in vitro
Author(s) -
Hirokawa Kazunori,
Aoki Nobuo
Publication year - 1991
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041470120
Subject(s) - umbilical vein , thrombomodulin , internalization , protein kinase c , protein kinase a , in vitro , human umbilical vein endothelial cell , tumor necrosis factor alpha , phorbol , kinase , microbiology and biotechnology , messenger rna , biology , chemistry , cell , biochemistry , endocrinology , thrombin , immunology , platelet , gene
It has been reported that thrombomodulin (TM) expression in endothelial cells is modulated by various agents. We investigated cellular regulatory mechanisms for TM expression in human umbilical vein endothelial cells (HUVECs), incubated with agents, by measuring the time course changes in surface TM activity, total TM antigen in cell lysates, and TM mRNA levels. While dibutyryl cAMP (3 mM) increased TM mRNA levels in HUVECs and was followed by increased TM activity, dibutyryl cGMP had no effect on TM activity. Phorbol myristate acetate (PMA) induced rapid loss of surface TM activity (∼8 h) and later increased TM mRNA levels between 4 h and 40 h (maximum at 24 h), resulting in biphasic effects on TM activity. Tumor necrosis factor or interleukin‐1β suppressed surface TM activity and TM mRNA levels. Internalization/degradation of TM in HUVECs incubated with PMA or cytokines was suggested by co‐culture with chloroquine. The decrease in surface TM activity observed was not caused by the release of TM molecules from the cells into the conditioned media. These results suggest that TM activity in HUVECs is modulated by independent mechanisms involving cytoplasmic TM mRNA levels and internalization/degradation of TM molecules. These regulatory mechanisms may involve protein kinase A and protein kinase C‐dependent mechanisms but are independent of protein kinase G.