Expression from cellular genes sharing overlapping polyadenylation signals is affected by ADAR editing. (A) In the human genome, ABHD1 and Sec 12 on chromosome 2 are expressed from opposite strands of the chromosome. Their AAUAAA polyadenylation signals overlap by 3 nt, generating potential transcript overlap very similar to that seen in polyomavirus. (B) Using siRNA, ADAR1 levels in HeLa cells were reduced by about threefold, compared with control and mock siRNA (against GFP) transfected samples. (C) Quantitative real-time RT-PCR shows that in the ADAR1 knockdown cells, the mRNA levels of mature ABHD1 and Sec12 both increase, compared to their levels in untreated cells or cells treated with siRNA against GFP. The results shown are representative of several independent experiments, with almost identical results. (D) RT-PCR supports the results from C.
