Jaewoong Jang

Aim: In this study, we report the anti-inflammatory activity of XAV939, a modulator of the Wnt/β-catenin pathway. Methods: WNT/β-catenin pathway and NF-κB signaling pathway were examined in LPS-stimulated human bronchial epithelial cells and effects of XAV939 on these pathways were analyzed. The effect of XAV939 was confirmed in human umbilical vein endothelial cells. Results: LPS-induced expressions of pro-inflammatory genes IL-6, IL-8, TNF-α, IL-1β, MCP-1, MMP-9, iNOS and COX-2 were significantly and dose-dependently suppressed by XAV939. LPS-induced NF-κB signaling, such as IκB phosphorylation and degradation as well as nuclear translocation of NF-κB, was also suppressed by XAV939. Target DNA binding of NF-κB was significantly and dose-dependently suppressed by XAV939 during LPS-induced inflammatory response. The suppressive effects of XAV939 on NF-κB signaling, target DNA binding of NF-κB and pro-inflammatory gene expression were all rescued by over expression of β-catenin, which shows that the anti-inflammatory effect of XAV939 is mediated by the modulation of β-catenin, a central component of the WNT/β-catenin pathway. Conclusion: The findings of this study showed that XAV939 exerts anti-inflammatory effects through the modulation of the Wnt/β-catenin pathway.

Jaewoong Jang, Yoosik Yoon, Dong-Jin Oh. Kidney Res Clin Pract 2017;36:224-31. https://doi.org/10.23876/j.krcp.2017.36.3.224

AMP-activated protein kinase (AMPK) and sterol regulatory element binding protein (SREBP)‑1c are major therapeutic targets in the treatment of metabolic diseases. In the present study, the fat‑reducing mechanisms of berberine (BBR), a natural isoquinoline, was investigated by examining the AMPK‑mediated modulation of SREBP‑1c in 3T3‑L1 adipocytes. BBR activated AMPK in a dose‑ and time‑dependent manner, and increased the phosphorylation of the 125‑kDa precursor form of SREBP‑1c, which suppressed its proteolytic processing into the mature 68‑kDa form and its subsequent nuclear translocation. The binding of nuclear SREBP‑1c to its E‑box motif‑containing target DNA sequence was decreased following treatment with BBR, which led to a decrease in the expression of lipogenic genes and subsequently reduced intracellular fat accumulation. Transfection with AMPKα1 siRNA, and not control siRNA, inhibited BBR‑induced phosphorylation of the 125‑kDa SREBP‑1c, which confirmed that AMPK was responsible for phosphorylating SREBP‑1c. AMPKα1 siRNA transfection rescued the proteolytic processing, nuclear translocation and target DNA binding of SREBP‑1c that had been suppressed by BBR. In addition, BBR‑induced suppression of lipogenic gene expression and intracellular fat accumulation were rescued by AMPKα1 siRNA transfection. In conclusion, the results of the present study demonstrate that BBR activates AMPK to induce phosphorylation of SREBP‑1c, thereby suppressing proteolytic processing, nuclear translocation and target DNA binding of SREBP‑1c, which leads to a reduction in lipogenic gene expression and intracellular fat accumulation. The results of the present study indicate that BBR may be a potential candidate for the development of drugs to treat obesity.

In this study, LPS-induced inflammatory responses in BEAS-2B human bronchial epithelial cells and human umbilical vein endothelial cell (HUVEC)s were found to be prevented by Dickkopf-1 (DKK-1), a secreted Wnt antagonist, and LGK974, a small molecular inhibitor of the Wnt secretion. LPS-induced IκB degradation and NF-κB nuclear translocation as well as the expressions of pro-inflammatory genes including IL-6, IL-8, TNF- α, IL-1β, MCP-1, MMP-9, COX-2 and iNOS, were all suppressed by DKK-1 and LGK974 in a dose-dependent manner. The suppressive effects of LGK974 on NF-κB, IκB, and pro-inflammatory gene expression were rescued by ectopic expression of β-catenin, suggesting that the anti-inflammatory activity of LGK974 is mediated by modulation of the Wnt/β-catenin pathway and not by unrelated side effects. When Wnt recombinant proteins were treated to cells, Wnt3a and Wnt5a significantly induced pro-inflammatory gene expressions, while Wnt7a and Wnt10b showed little effects. It was also found that Wnt3a and Wnt5a expressions were significantly induced by LPS treatment. Consistently, knockdown of Wnt3a and Wnt5a blocked LPS-induced inflammatory responses, while treatment of recombinant Wnt3a and Wnt5a proteins rescued the inhibition of inflammatory responses by LGK974. Findings of this study showed that DKK-1 and LGK974 suppress LPS-induced inflammatory response by modulating Wnt/β-catenin pathway.

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Lipoteichoic acid (LTA) is a major cell wall component and virulence factor of gram-positive bacteria. The present study investigated the LTA‑induced inflammatory response of BEAS‑2B human bronchial epithelial cells, and detected the expression levels of proinflammatory cytokines interleukin (IL)‑6, IL‑8, IL‑1β, tumour necrosis factor‑α and monocyte chemotactic protein‑1, the upregulation of NF‑κB, and the phosphorylation and degradation of I‑κB. During the LTA‑induced inflammatory response of the BEAS‑2B human bronchial epithelial cells, the activity levels of the β‑catenin‑dependent promoter, and the protein expression levels of β‑catenin were significantly upregulated, whereas β‑catenin phosphorylation and the expression levels of AXIN were significantly downregulated. Following knockdown of β‑catenin by small interfering (si)RNA transfection, both the LTA-induced protein expression levels of NF‑κB and the LTA-induced activity levels of the NF‑κB‑dependent promoter were significantly reduced. Similarly, a marked reduction in I‑κB phosphorylation and degradation was observed following β‑catenin knockdown. The expression levels of the LTA‑induced proinflammatory cytokines were also significantly reduced following β‑catenin siRNA. These results suggest that β‑catenin has a significant role in the regulation of NF‑κB activity and proinflammatory cytokine expression during the LTA-induced inflammatory response of bronchial epithelial cells.

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The modulations of β-catenin were analyzed during the inflammatory response induced by the Der p 1 house dust mite allergen. Der p 1 induced the dose-dependent expression of inflammatory cytokines, including interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) in THP-1 human monocytic cells. The mRNA expression levels of β-catenin were not altered, however protein levels increased following Der p 1 treatment, demonstrating that β-catenin was modulated by post-transcriptional processes. It was also revealed that nuclear β-catenin levels were significantly increased while cytoplasmic β-catenin levels were reduced, which demonstrated the nuclear translocation of β-catenin by the Der p 1 allergen. Glycogen synthase kinase 3β (GSK3β), a regulator of β-catenin stability, was demonstrated to be phosphorylated following Der p 1 treatment. When β-catenin was knocked down by the transfection of its small interfering RNA (siRNA), inflammatory cytokine expression as well as nuclear factor-κB (NF-κB) activity, which were induced by Der p 1 treatment, were all significantly reduced. The results demonstrated that Der p 1-induced inflammatory responses were mediated by β-catenin.