INDUCTION OF C-FOS EXPRESSION IN RAT VASCULAR SMOOTH-MUSCLE REPORTER CELLS BY SELECTIVE ACTIVATION OF THE THROMBIN RECEPTOR

The rat vascular smooth muscle cell (VSMC) line A10 (ATCC CRL 1476) wa s stably transfected with a human c-fos promoter-driven luciferase rep orter gene to monitor thrombin receptor activation and subsequent indu ction of c-fos expression. Selective activation of the endogeneous thr ombin receptor by the thrombin receptor activating peptide (TRAP(1-6)) , SFLLRN, is shown here to result in a significant transient increase of intracellular [Ca2+], dose-dependent induction of c-fos promoter-me diated luciferase activity, and stimulation of DNA synthesis. These da ta demonstrate that A10 cells and reporter line derivatives thereof po ssess a functional thrombin receptor very similar or identical to that previously described. Results obtained with various signal transducti on modulating or inhibiting agents support previous notions showing th at thrombin receptor activation by SFLLRN is coupled to events involvi ng p21(ras) activation, protein tyrosine kinase, and activation of PKC . The A10 reporter line described here proved to be a helpful and reli able tool to study alpha-thrombin and TRAP(1-6)-mediated intracellular events, since it retained most of the spectrum of biological response s found in primary VSMC cultures.