HEK293 cells were seeded onto 12-well plates and transfected with 0.5 μg of the Klotho promoter construct using Lipofectamine™
2000 (Invitrogen) according to the manufacturer's instructions. To
monitor transfection efficiency, 50 ng of the pRL-null plasmidencoding Renilla luciferase was included in all samples. Whereindicated, 0.2 μg mammalian expression vectors were also included. EGF induces Klotho mRNA expression. HEK293 cells were stimulated with 100 ng/mL EGF for different time periods. Total RNA was isolated and assessed for Klotho mRNA expression by Northern blot analysis (A) and relative expression levels of
Klotho mRNA were measured by quantitative real-time PCR (B). Relative levels were normalized to the level of gapdh mRNA. The data shown represent the mean±S.D. of three independent experiments performed in triplicate.