Effect Of Fluoxetine Along Mek/erk 5 Pathway Inhibited By Novel Mek 5 Inhibitor In Embryonic Rat Neuronal Stem Cells

Background Fluoxetine has been studied to activate extracellular signal-regulated kinase 1/2 (ERK 1/2) but not extracellular signal-regulated kinase 5 (ERK 5) in specific which sequences has been found to resemble with ERK 1/2.Objective To investigate the effect of fluoxetine to extracellular signal-regulated kinase 5 (ERK5) on mouse embryonic hippocampus neural stem cell (NSCs) inhibited by BIX02188, as novel mitogen-activated protein kinase kinase 5 (M EK 5) selective inhibitor.Methods In this study we examined the affectivity of BIX02188 as novel selective MEK 5 inhibitor in NSCs with nerve growth factor (NGF) as stimulated agent. Later, we used MEK 5 selective inhibitor BIX02188 and mitogen-activated protein kinase kinase 1/2 (MEK 1/2) selective inhibitor PD98059 to inhibit NSCs at MEK 1/2 and MEK 5 respectively and stimulated phosphorylation of both ERK 1/2 and ERK 5 by fluoxetine. All detection was done by western blot method and analyzed by Student t-test and ANOVA. Result It was observed that MEK 5 specific inhibitor BIX02188 inhibited the formation of neurospheres and specifically blocked ERK 5 phosphorylation but not ERK 1/2 phosphorylation. Nerve growth factor (NGF) significantly increased the phosphorylation of ERK 5 and acted as activator following inhibition by BIX02188. NGF activated phosphorylation of both ERK 1/2 and ERK. After be treated with 20μM PD98059 and 15μM BIX20188, and then activated by fluoxetine, there was significance increase phosphorylation of both ERK 1/2 and ERK 5.Conclusion Fluoxetine activates ERK 5 is essential for the proliferation of NSCs derived from mouse embryonic hippocampus. Taking these results together, fluoxetine not only played important role along MEK/ERK 1/2 but also MEK/ERK 5 pathway aside from MEK/ERK 1/2 interference.