Fig. 5.

A putative Stat3 binding site regulates apelin promoter activity. Top schematic: a putative Stat3 binding site is identified in the wild-type (WT) apelin promoter sequence of the rat (−198/−195 bp); mutated nucleotides are indicated in bold in the mutated (Mut) sequence. Only partial sequences of WT and Mut promoters are shown. A: transient transfection experiments show that Stat3 overexpression increases apelin promoter activity in apelin promoter deletion-luciferase reporter constructs (−407/−1, −302/−1, −207/−1 bp). Promoter activity of the −106/−1 bp apelin promoter reporter construct was not influenced by Stat3 overexpression. B: mutation of a putative Stat3 binding site (−198/−195 bp) in the rat apelin core promoter abolished the elevation in apelin promoter activity induced by Stat3 overexpression. C: mutation of the putative Stat3 binding site inhibited the elevation in apelin promoter activity induced by LPS treatment. *P < 0.05 vs. control levels.