During in vivo maturation of eukaryotic nuclear mRNA, splicing yields excised exon circles.
Circular splicing has already been described on nuclear pre-mRNA for certain splice sites far apart in the multi exonic ETS-1 gene and in the single 1.2 kb exon of the Sry locus. To date, it is unclear how splice site juxtaposition occurs in normal and circular splicing. The splice site selection of an internal exon is likely to involve pairing between splice sites across that exon. Based on this, we predict that, albeit at low frequency, internal exons yield circular RNA by splicing as an error-prone mechanism of exon juxtaposition or, perhaps more interestingly, as a regulated mechanism on alternative exons. To address this question, the circular exon formation was analyzed at three ETS-1 internal exons (one alternative spliced exon and two constitutive), in human cell line and blood cell samples. Here, we show by RT-PCR and sequencing that exon circular splicing occurs at the three individual exons that we examined. RNase protection experiments suggest that there is no correlation between exon circle expression and exon skipping.
Bailleul
B
B
Unite 124 INSERM, Institut de Recherches sur le Cancer de Lille, France.
D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D005091:Exons; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000235:genetics; D050783:Proto-Oncogene Proteins c-ets; D011519:Proto-Oncogenes; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing; D000079962:RNA, Circular; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics
D017931:DNA Primers; C494041:ETS1 protein, human; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D000079962:RNA, Circular; D012333:RNA, Messenger; D014157:Transcription Factors; D012313:RNA