Activation of Krüppel-Like Factor 2 with Ginkgo Biloba Extract Induces eNOS Expression and Increases NO Production in Cultured Human Umbilical Endothelial Cells.

ABSTRACT

BACKGROUND: The mechanisms responsible for the effects of Ginkgo biloba extract (GbE) are not fully understood. Krüppel-like factor 2 (KLF2), a zinc transcription factor, has vasculoprotective effects if activated. The present study attempted to explore whether GbE may activate KLF2 and its consequences. METHODS: To determine the effects of GbE on endothelial cells, human umbilical vein endothelial cells (HUVECs) were incubated with various concentrations of GbE. KLF2 expression levels were determined by quantitative reverse transcription polymerase chain reaction. Cytoskeleton staining and cell migration assays were performed to determine the effects of KLF2 activation. Moreover, endothelial NO synthase (eNOS) expression levels were detected by PCR and Western blot testing. Nitric oxide (NO) production was also measured with 4,5-diaminofluorescein. A knockdown of KLF2 was performed to identify the role of KLF2 in GbE-induced eNOS expression and NO production. RESULTS: HUVECs that were incubated with GbE increased KLF2 expression. These cells demonstrated an altered cell morphology, cytoskeleton rearrangement, and inhibited migration activity. Moreover, eNOS expression and NO production increased in a dose-dependent manner when cells were treated with GbE. Correspondingly, silencing of KLF2 in HUVECs decreased eNOS expression and NO production in GbE-treated cells. CONCLUSIONS: GbE significantly activated KLF2 expression and KLF2-related endothelial function, including cytoskeleton rearrangement, inhibition of migration, eNOS activation, and NO production. These findings suggest that GbE may induce a vasculoprotective effect in endothelial cells. KEY WORDS Endothelial cells; eNOS; Ginkgo biloba extract; KLF2; NO.