[Induction effect of platelet-activating factor on Src-suppressed C kinase substrate gene expression in rat pulmonary microvascular endothelial cells].

Objective: To investigate the effect of platelet-activating factor (PAF) on the production of Src-suppressed C kinase substrate (SSeCKS) mRNA in rat pulmonary microvascular endothelial cell (RPMVEC) and its signal transduction pathways.

Methods: Cellular in situ hybridization was performed to reveal changes in SSeCKS mRNA expression in the cultured RPMVECs after giving PAF stimulation.

Results: Normal RPMVECs expressed SSeCKS mRNA at a low level, which appeared throughout the cytoplasm with specific hybridization signals. 1.5 hours of 10(-10), 10(-9), 10(-8), 10(-7) mol/L PAF incubation induced a progressive increase in SSeCKS mRNA expression. When compared to the normal control group each difference had statistical significance (0.054 9 + or - 0.000 7, 0.059 9 + or - 0.001 8, 0.069 0 + or - 0.001 8, 0.075 4 + or - 0.001 9 vs. 0.036 8 + or - 0.003 7, respectively, all P<0.05). Within 0.5, 1.5, 3, 6, 12, 24 hours of 10(-7) mol/L PAF challenge, the level of SSeCKS mRNA expression raised at 0.5 hour markedly (0.071 0 + or - 0.001 5), peaked at 1.5 hours (0.075 6 + or - 0.001 7), then began to decline gradually, and still persisted at a higher level than the normal control group until 24 hours (0.043 9 + or - 0.001 0 vs. 0.038 2 + or - 0.004 1, all P<0.05). Pre-incubation of 10 micromol/L pyrrolidine dithiocarbamate (PDTC) that inhibits activity of nuclear factor-KappaB (NF-KappaB) in RPMVECs caused a conspicuous attenuation of PAF-induced SSeCKS mRNA expression (0.049 7 + or - 0.003 2 vs. 0.071 9 + or - 0.001 9, P<0.05), whereas no change of PAF-induced effect was found by pretreatment of protein kinase C (PKC) inhibitor bis-indolylmaleimide (BIM, 0.069 7 + or - 0.002 1 vs. 0.071 9 + or - 0.001 9, P>0.05).

Conclusion: PAF can up regulate the expression of SSeCKS mRNA in a dose- and time-dependent manner in RPMVECs. It is NF-KappaB rather than PKC signal pathway that is involved in modulation of the intracellular signaling process.