Dependence of Proximal GC Boxes and Binding Transcription Factors in the Regulation of Basal and Valproic Acid-Induced Expression of t-PA

Figure 4

t-PA mRNA expression after siRNA mediated knock-down of Sp factors. HUVECs were treated with siRNA targeting Sp1, Sp2, Sp3, or Sp4 for 72 h and then stimulated with 3 mM VPA for 24 h. Statistical comparisons are made relative to untreated control cells. The marks indicate the statistical comparisons of the VPA-induction in nontransfected cells versus the VPA-induction in transfected cells ( = change in t-PA mRNA expression after VPA stimulation). , , and . The results are presented as mean values ± SEM of four independent experiments. The statistical evaluation was performed using paired Student’s -test together with Bonferroni correction for multiple analysis. Not shown in the illustrations are transfection controls with transfection reagent only (mock) and transfection with “All Star Negative” control siRNA (ASN) that were included in each experiment. These negative controls showed no significant effect on either t-PA or target mRNA.