TransCirc 2.0: a multi-species resource for translatable circular RNAs and cognate translation products

TransCirc is an evidence-integrated database for evaluating the translation potential of circular RNAs (circRNAs) and their putative products. Here, we present TransCirc 2.0, a major update that expands this resource from a primarily human-focused database to 10 vertebrate species, comprising more than 2.8 million circRNAs and increasing coverage by approximately 10-fold through the integration of standardized full-length circRNA sequences. Within the original multi-evidence framework, we incorporate additional evidence, including translation initiation sites, internal ribosome entry sites, N6-methyladenosine, ribosome/polysome association, and mass spectrometry (MS), together with circRNA-specific open reading frame and sequence-composition annotations. In light of recent advances in AI-based RNA modeling, we further incorporate multiple regulatory features predicted by TranslationAI and LAMAR. The circRNA-encoded proteins are further annotated for degron-associated stability and degradation properties, while MS-supported peptides are evaluated for potential MHC-I presentation. Collectively, these updates establish a cross-species framework linking full-length circRNA sequences with multi-level translation evidence and downstream product annotations, supporting systematic evaluation of circRNA translation potential and putative translation products. TransCirc 2.0 is freely available at https://www.biosino.org/transcirc/.