P215 The effect of cordycepin and its analogues on poly- adenylation and protein synthesis

The polyadenylation inhibitor cordycepin has been shown to have promise as an antiproliferative agent, as it activates AMP activated kinase and inhibits the mTOR pathway. We have shown that some mRNAs are much more sensitive to cordycepin than others. By comparing the sensitivity of mRNAs to cordycepin and to transcription inhibitors using microarray, we found that most mRNAs that are sensitive to cordycepin are also sensitive to a transcription inhibitors. This indicates that the majority of mRNAs targeted by cordycepin are unstable, highly transcribed mRNAs that are highly dependent on nuclear polyadenylation. We are currently investigating other adenosine analogues, which may induce chain termination during polyadenylation or directly inhibit the enzyme. We will study the effect of these analogues on signal transduction and poly(A) tail length. Not all poly(A) polymerases (PAPs) may be affected to the same extent by different adenosine analogues. To determine the spe- cificity of polyadenylation inhibitors for different PAPs, we have designed tethering assay, in which catalytic domain of a PAP is fused to an RNA binding protein, increasing the expression of a reporter in the absence of inhibitor. This work will lead to better understanding of gene regulation by PAPs and assess their potential as drug targets.