Daidzein phosphorylates and activates 5-lipoxygenase via the MEK/ERK pathway: a mechanism for inducing the production of 5-lipoxygenase metabolite that inhibit influenza virus intracellular replication.

We previously reported that the soy isoflavone daidzein (Dz) suppresses the intracellular replication of influenza virus and that arachidonic acid-derived oxidation product via lipid oxidase 5-lipoxygenase (5-LOX) is involved in its antiviral effect. The activation of 5-LOX by Dz triggers anti-influenza activity; however, the mechanism of activation of 5-LOX remains unclear. Therefore, in this study, we aimed to clarify the activation mechanism using human monocyte-derived THP-1 cells differentiated using phorbol 12-myristate 13-acetate. THP-1 cells expressed 5-LOX endogenously and Dz did not induce 5-LOX expression. However, 8 h after treatment with Dz, the amount of 5-hydroxyeicosatetraenoic acid (5-HETE), an arachidonic acid oxidation product via 5-LOX, increased significantly suggesting that the enzyme is activated regardless of changes in 5-LOX protein levels. Intracellular Ca2+ content, ATP concentration, 5-LOX protein phosphorylation, and 5-LOX intracellular localization are known 5-LOX activation factors. The intracellular Ca2+ and ATP concentrations were not affected by Dz treatment. The enzymatic activity of 5-LOX is regulated by the phosphorylation of three serine residues and four tyrosine residues. Pretreatment with inhibitors of each kinase revealed that Dz-induced 5-HETE production was suppressed by the MEK/ERK inhibitor. 5-LOX in which the Ser663 residue was phosphorylated was found to be increased in the nuclear fraction of Dz-treated THP-1 cells. Furthermore, immunocytochemistry showed that 5-LOX translocates to the nuclear envelope following Dz treatment. These results indicate that Dz activates 5-LOX by phosphorylating Ser663 via the MEK/ERK pathway. Thus, these results demonstrate that Dz exerts anti-influenza virus activity via the MEK/ERK signal transduction pathway.

The Effects ofβ-Sheet Breaker Peptide H102 on ERK Signal Transduction Pathway in Brain of PAP Double Transgenic Mice / 天津医药

Objective To investigate the activation of β-sheet breaker peptide H102 on ERK signal transduction pathway in brain of PAP double transgenic mice. Methods PAP double transgenic mice were randomly divided into model group and H102 treatment group (n=10 for each group). A group of C57BL/6J mice with the same genetic background was served as controls. H102 (5.8 mg/kg) 5 μL was infused by intranasal administration to mice in H102 treatment group, and equal volume of blank solution of H102 (chitosan, BSA) was given to mice in control group and model group. The ability of spatial reference memory was tested by Morris water maze after 30 days of treatment. Then immunohistochemistry tests and Western blot technique were used to detect the content of RAS, P-MEK and P-ERK proteins in mouse brain. Results (1) The ability of learning and memory was significantly lower in model group than that of control group. The ability of learning and memory was significantly improved in treatment group than that in model group (P<0.05). (2) The contents of RAS, P-MEK and P-ERK in mouse brain were significantly lower in model group than those of control group, and these protein ex-pressions were significantly increased in treatment group than those in model group (P<0.01). Conclusion β-sheet break-er peptide H102 can activate ERK signal transduction pathway in brain of PAP double transgenic mice, increase PAS, P-MEK and P-ERK levels in nerve cells, and improve the ability of learning and memory in PAP mice.