Figure 5.

PERK Regulates the Activation of Transcription Factors STAT3 and SRF

SMCs were cultured, starved, and then pre-treated with PERK inhibitor (A) or siRNA (B) and then treated with solvent or PDGF-BB (100 ng/ml) for 24 h as described previously. (A and B) Immunoblots of STAT3 phosphorylation in SMCs. Shown are representative blots from 1 of 2 similar experiments. (C) Coimmunoprecipitation. HA-STAT3 or HA vector control was transfected into MOVAS before pre-treatment with PERK inhibitor and treatment with PDGF-BB. Cell lysates were enriched using HA antibody, and then probed for PERK and MRTFA. (D) Luciferase assay for SRF transcriptional activity. Human aortic SMCs were transfected with a vector containing SRF response elements. Putative SRF activity was compared between 2 conditions: adenoviral overexpression of PERK (Ad-PERK) or GFP control (Ad-GFP), n = 5; mean ± SEM, ***p < 0.001, paired Student’s t-test. HA = hemagglutinin; MRTF-A = myocardin related transcription factor A; STAT3 = signal transducer and activator of transcription 3; other abbreviations as in Figures 1, 3, 4, and 5.