Figure 1.

Platelets contain TF pre-mRNA and splice it into mature message in response to activation. (A) TF and GAPDH mRNA expression in freshly isolated platelets (0 min), platelets adherent to fibrinogen and coactivated with thrombin (Fib + Thr), or HL60 leukocytes. The negative control lane (Neg con) is a PCR reaction conducted without cDNA template. A is representative of two independent experiments. (B and C) TF and GAPDH mRNA expression in freshly isolated platelets (Control) or platelets that are adherent to fibrinogen in the presence of thrombin (Fib + Thr). The negative control lane (Neg con) in C is a PCR reaction conducted without cDNA template. B and C are representative of >10 independent experiments. (D) Indirect in situ PCR for intronic TF pre-mRNA in megakaryocytes (left) and megakaryocytes with proplatelet extensions (right). In the bottom panels (no RT), the reverse transcriptase (RT) was omitted from the RT reaction. (E) Direct in situ PCR for TF pre-mRNA was conducted in quiescent platelets (top left), whereas PCR for mature TF mRNA was conducted in platelets adherent to fibrinogen in the presence of thrombin for 1 h (top right). In the bottom panels (no RT), the reverse transcriptase was omitted during the RT reaction. D and E are representative of three independent experiments.