Effect of notch1,2,3 genes silicing on NF-κB signaling pathway of macrophages in patients with atherosclerosis

Abstract

Background: Notch and NF-κB signaling pathways both play important roles in the regulation of atherosclerosis (AS). However, the mechanisms of notch and NF-κB signaling pathways on AS are still unclear. In this study, we aimed to investigate the effects of notch1,2,3 genes silicing by siRNA on notch and NF-κB signaling pathways of macrophages in patients with atherosclerosis (AS), so as to seek the treatment of AS from genetic perspective.

Methods: Peripheral blood mononuclears of 31 patients with AS were isolated by density gradient centrifugation and transformed by PMA to macrophages. Then macrophages were transfected with notch1-siRNA (notch1-siRNA group), notch2-siRNA (notch2-siRNA group), notch3-siRNA (notch3-siRNA group), negative control siRNA (NC group) and none (control group). RT-PCR and Western blot analysis were applied to assess the expression level of Delta-like-4 (DLL4), Jagged-1 (JAG1), IκBα and P52. Electrophoretic mobility shift assay (EMSA) was used to observe the NF-κB DNA binding activity. Subcellular distributions of NF-κB/P52 were detected through immunofluorescence. mRNA expression levels of TNF-α, IL-6 and IL-6 in macrophages were also determined with RT- PCR. The expression of 20S proteasome was detected by Western blot.

Results: After transfected with siRNA, there was no difference in the expression of DLL4, JAG1, IκBα and P52 between NC group and control group (p>0.05). Compared with NC group and control group, the expression of DLL4, P52 and JAG1 in notch1-siRNA group, notch2-siRNA group and notch3-siRNA group was significantly downregulated (p<0.05 or p<0.01, respectively), whereas the expression of IκBα was significantly increased (P<0.05 or p<0.01, respectively), especially in notch1-siRNA group. The binding activity of NF-κB DNA was lower in notch1- siRNA group, notch2-siRNA group and notch3-siRNA group compared with NC group and control group (p<0.05), especially in notch1-siRNA group. The fluorescence intensity of p52 was decreased significantly both in the nucleus and cytoplasm in notch1-siRNA group, notch2-siRNA group and notch3-siRNA group compared with NC group and control group (p<0.05), which decreased more obviously in the nucleus, especially in notch1-siRNA group. The TNF-α, IL-1 and IL-6 expression of notch1-siRNA group, notch2-siRNA group and notch3-siRNA group was lower compared to NC group and control group (p<0.05 or p<0.01, respectively), also especially in notch1-siRNA group. 20S proteasome level was significantly lower in notch1-siRNA group, notch2-siRNA group and notch3-siRNA group than in NC group and control group (p<0.05 or p<0.01, respectively), especially in notch1-siRNA group.

Conclusions: There was a positive regulation between Notch and NF-κB signaling pathway in patients with AS. Notch1 may play a more important role than notch2 and notch 3 in the regulation of NF-κB signaling pathway in AS.

Keywords: Atherosclerosis; Macrophages; NF-κB signaling pathway; Notch signaling pathway; RNA interference.