G. Pages et al., Stress-activated protein kinases (JNK and p38/HOG) are essential for vascular endothelial growth factor mRNA stability, J BIOL CHEM, 275(34), 2000, pp. 26484-26491
Stability of the vascular endothelial growth factor (VEGF) mRNA is tightly
regulated through its 3'-untranslated region (3'-UTR). Here, we demonstrate
that VEGF mRNA levels are increased by anisomycin, a strong activator of s
tress-activated protein kinases. Hence, VEGF mRNA induction is inhibited by
SB202190, an inhibitor of JNK and p38/HOG kinase, Furthermore, VEGF mRNA e
xpression is increased in cells that overexpress JNK and p38/HOG; by an inc
rease in its stability. We show by two different approaches that anisomycin
exerts its effect on the VEGF mRNA 3'-UTR. First, by using an in vitro mRN
A degradation assay, the half-life of the VEGF mRNA 3'-UTR region transcrip
t was found to be increased when incubated with extracts from anisomycin-tr
eated cells; and second, the 3'-UTR was also sufficient to confer mRNA inst
ability to the Nhe3 (Na+/H+ exchanger 3) heterologous reporter gene, and an
isomycin treatment stabilized the chimeric mRNA (Nhe3 fused to the VEGF mRN
A 3'-UTR). This chimeric mRNA is also more stable in cells overexpressing p
38/HOG and JNK that have been stimulated by anisomycin. We show that such r
egulation is mediated through an AU-rich region of the 3'-UTR contained wit
hin a stable hairpin structure. By RNA electrophoretic mobility shift assay
s, we show that this region binds proteins specifically induced by anisomyc
in treatment. These findings clearly demonstrate a major role of stress-act
ivated protein kinases in the post-transcriptional regulation of VEGF.