We report the antiapoptotic effect of RNA-binding protein HuR, a critical 
regulator of the post-transcriptional fate of target transcripts. Among the most 
prominent mRNAs complexing with HuR is that encoding prothymosin alpha 
(ProTalpha), an inhibitor of the apoptosome. In HeLa cells, treatment with the 
apoptotic stimulus ultraviolet light (UVC) triggered the mobilization of 
ProTalpha mRNA to the cytoplasm and onto heavier polysomes, where its 
association with HuR increased dramatically. Analysis of a chimeric ProTalpha 
mRNA directly implicated HuR in regulating ProTalpha production: ProTalpha 
translation and cytoplasmic concentration increased in HuR-overexpressing cells 
and declined in cells in which HuR levels were lowered by RNA interference. 
Importantly, the antiapoptotic influence engendered by HuR was vitally dependent 
on ProTalpha expression, since use of oligomers that blocked ProTalpha 
translation abrogated the protective effect of HuR. Together, our data support a 
regulatory scheme whereby HuR binds the ProTalpha mRNA, elevates its cytoplasmic 
abundance and translation, and thereby elicits an antiapoptotic program.