Illumina bead array -/+ UV ASCC3 short isoform knockout cells

The transcription-related DNA damage response was analyzed on a genome-wide scale with great spatial and temporal resolution. Upon UV irradiation, a slowdown of transcript elongation and restriction of gene activity to the promoter-proximal ~25 kilobases is observed. This is associated with a shift from expression of long mRNAs to shorter isoforms, incorporating alternative last exons (ALEs) that are more proximal to the transcription start site. Notably, this includes a shift from a protein-coding ASCC3 mRNA to a shorter transcript isoform of which the RNA, rather than an encoded protein, is critical for the eventual recovery of transcription. The protein-coding ASCC3 isoform counteracts the function of the non-coding isoform, indicating crosstalk between them. Thus, the ASCC3 gene expresses both coding and noncoding transcript isoforms with opposite effects on transcription recovery after UV-induced DNA damage MRC5VA parental cells and MRC5VA ASCC3 short isoform (NM_022091.4) knockout cells were left untreated or UV irradiated 15 J/m2, followed by 20 hours recovery. RNA extracted from 3 biological replicates per sample were analyzed on Illumina Human HT-12 bead expression array.