When wild-type cells were transfected with NF-kB p65 expression plasmid, the mRNA level of BACE1 was elevated by 476.6¡21.68% (p<0.0001 relative to controls) (Fig. 5b).
Compared to controls, TNF-a treatment resulted in significant increase in luciferase activity in the cells transfected with the human BACE1 promoter pB1P- N1 plasmid (p<0.005) and addition of aspirin in- hibited the BACE1 transcriptional activation induced by TNF-a (p<0.005 relative to TNF-a and p>0.05 relative to controls) (Fig. 6a).
Consistent with pB1P-N1 plasmid results, TNF-a significantly induced BACE1-NF-kB promoter activation (p<0.005) and the NSAIDs aspirin, ibuprofen and indomethacin significantly blocked the TNF-a-induced BACE1- NF-kB promoter activation (p<0.005) (Fig. 6b).
Our data clearly demonstrate that NSAIDs inhibit TNF-a-induced BACE1 transcription via its NF-kB cis-acting elements.
Inflammation is one of major pathological changes in AD brains and NF-kB signalling plays an important role in inflammation and oxidative stress (Tong et al. 2005).
These results suggest that the 4NF-kB oligonucleotides con- taining four putative NF-kB-binding elements from the human BACE1 promoter is able to respond to NF-kB signalling to modulate a downstream gene transcription.
Consistent with our Western blot results, a significant elevation of promoter activity was detected in cells co- expressing BACE1 reporter plasmid and NF-kB p65 (Fig. 3d).
The results showed that the protein level of p65 sig- nificantly increased to 155.40¡13.39% in AD patient samples relative to control samples (p<0.05) (Fig. 1a).
Our result showed that p65 overexpression significantly increased BACE1 protein level by 232.54¡12.86% (p<0.01 relative to controls) (Fig. 5g).
p65 expression significantly increased the amount of C99 in 20E2 cells by 152.29¡6.03% in the presence of NF-kB p65 relative to controls (p<0.001) (Fig. 5h, i).
There was no significant difference in APP level between p65 transfected cells and controls (p>0.05).
The results showed that NF-kB p65 expression significantly increased total Ab protein concentration by 134.90¡5.74% in SAS1 cells, a stable SH-SY5Y cell stably expressing Swedish mutant APP695 (Sun et al. 2006a) (p<0.0001) (Fig. 5j).
BACE1 mRNA levels were also markedly increased in the cortex of AD patients (126.40¡9.01% relative to controls, p<0.05) (Fig. 1b).
IkBa expression plasmid was also transfected into SAS1 cells and IkBa transfection reduced Ab protein levels to 92.24¡2.68% (p<0.05).
TNF-a is a strong activator of NF-kB signalling pathways.
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If you find BEL Commons useful in your work, please consider citing: Hoyt, C. T., Domingo-Fernández, D., & Hofmann-Apitius, M. (2018). BEL Commons: an environment for exploration and analysis of networks encoded in Biological Expression Language. Database, 2018(3), 1–11.