Fig. 1.

Decoding circR-loop: from transcription regulation to organ development and cancer progression. CircRNAs, transcribed from DNA, can engage with the sequence of their parent genes during RNA:DNA interactions, forming circR-loop when the transcription bubble of the parent gene is formed. Distinguishing circRNAs from linear genes typically involves a combination of enzymatic treatment and sequencing methods. Meanwhile, the characterization of circR-loop is predominantly conducted through DRIP technology and FISH coupled with RIP sequencing. circR-loop plays pivotal roles in inhibiting transcription, regulating alternative splicing, mediating chromatin reorganization, and DNA damage, as verified through corresponding phenotypic experiments. Presently, circR-loop has been predominantly identified in plants, where they mediate organ development. In animals, they are primarily implicated in the regulation of cancer progression. These effects are often validated through gain- and loss-of-function experiments, providing valuable insights into their functional significance. CircRNAs, circularRNAs; DRIP, DNA:RNA hybrid immunoprecipitation; FISH, fluorescence in situ hybridization; RIP, RNA binding protein immunoprecipitation