Expression of COX-2 in platelet-monocyte interactions occurs via combinatorial regulation involving adhesion and cytokine signaling
J. Clin. Invest. Dan A. Dixon, et al. 116:2727 doi:10.1172/JCI27209 [
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Figure 2Prolonged adherence to activated platelets modulates COX-2 synthesis and mRNA stability in monocytes. (
A) Time courses of COX-2 mRNA (left panel) and protein (right panel) expression in monocytes. Platelets (10
8 cells) were incubated with monocytes (10
6 cells) in the presence of thrombin. At the indicated times, COX-2 mRNA was detected by RNase protection assay. 28S RNA is shown as a control for RNA loading. COX-2 protein was detected by immunoblot of total cell lysates. β-actin was detected on the same blot as a control for protein loading. Data shown represent 3 experiments. (
B) Time courses of COX-2 mRNA (left panel) and protein (right panel) expression in monocytes treated with TNF-α (100 U/ml) were assayed as described in
A, except platelets were omitted. (
C) Assays of COX-2 mRNA
t1/2 were accomplished by adding 5 μg/ml ActD to platelet-monocyte suspensions treated with thrombin for 0.5 hours (top panel) or 18 hours (bottom panel). Total RNA was prepared at the indicated time points and COX-2 mRNA decay was analyzed by Northern blot probing for COX-2. 18S RNA is shown as a control for RNA loading. (
D) Summary of COX-2 mRNA
t1/2 data obtained from platelet-monocyte suspensions treated with thrombin for 0.5 hours (filled circles) and 18 hours (open circles) showing the average and range in duplicate experiments.
