Mechanism of glucocorticoid receptor activation regulated expression of thrombospondin-1

Objective: Thrombospondin-1 (TSP-1) plays an important role in platelet activation and aggregation and aggravates thrombosis. Chronic stress can cause a variety of diseases, including coagulation disorders, increased thrombosis, atherosclerosis, and a series of cardiovascular and cerebrovascular diseases. However, it is still unknown how chronic stress regulates the expression of TSP-1 after glucocorticoid receptor activation. Approach and Results: rats chronic unpredictable mild stress model was applied and the changes of TSP-1 and microRNAs in plasma were examined. Effects of glucocorticoid receptor activation on human umbilical vein endothelial cells and platelets were observed. Glucocorticoid receptor (GR) activation upregulated the expression of TSP-1 and downregulated the expression of microRNA-1-3p accompanied with increase of phosphorylation of p38 mitogen-activated protein kinase (MAPK) and argonaute-2 (AGO-2). Blockade of p38 MAPK phosphorylation resulted in decrease of phosphorylation level of AGO-2, increase of microRNA-1-3p expression, and decrease of TSP-1 expression. Transfection of AGO-2 Y393F point mutant plasmid, increased microRNA-1-3p expression and decreased TSP-1 expression, transfection of microRNA-1-3p mimic also decreased TSP-1 expression, while transfection of microRNA-1-3p inhibitor increased TSP-1 expression. Finally, GR activation led to an increase in the phosphorylation level of p38 MAPK in platelets and an increase in the level of TSP-1 in the supernatant. Conclusions: our study demonstrates that GR activation in HUVEC stimulates the phosphorylation of p38 MAPK, which in turn promotes the phosphorylation of AGO-2 and inhibits the maturation of microRNA-1-3p, leading to elevated expression of TSP-1, GR activation in platelets leads to the release of TSP-1. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=147 SRC="FIGDIR/small/536820v1_ufig1.gif" ALT="Figure 1"> View larger version (45K): org.highwire.dtl.DTLVardef@86e8ecorg.highwire.dtl.DTLVardef@126094eorg.highwire.dtl.DTLVardef@2d13c3org.highwire.dtl.DTLVardef@16c79c3_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO HSS: Hydrocortisone sodium succinate C_FIG