Effects of other thiol-containing compounds and tunicamycin on ATF3 mRNA and JNK/SAPK and in aortic endothelial cells.

(A) HUVECs were treated with 3 mmol/L each of the indicated compounds or 10 μg/mL tunicamycin for 4 hours, and their total RNA and whole-cell extracts were assayed for ATF3 mRNA and phosphorylated JNK/SAPK (JNK-○P), respectively, as in Figures 1 and 2. For the NAC effect, cells were pretreated with 20 mmol/LN-acetyl-l-cysteine for 1 hour. There was statistically significant activation from the control; *P < .0001, n = 3. (B) Both subconfluent (sub) and confluent HUVECs or HAECs were incubated in the absence (open columns) or presence (solid columns) of 3 mmol/L homocysteine for 4 hours, and their ATF3 expression and phosphorylation of JNK/SAPK (JNK-○P) were measured as in panel A. In both panel A and panel B, the relative expression of ATF3 mRNA is given in arbitrary units and represents the mean of 3 independent experiments with an SE bar. Statistically significant activation was found in the presence of homocysteine; *P < .0001, n = 3.