PTBP1-mediated inhibition of circular RNA SCMH1 biogenesis impairs brain recovery after ischemic stroke

RATIONALE: Aberrant circular RNA (circRNA) expression is implicated in various diseases, but the regulatory mechanisms remain poorly understood. Our previous work identified circSCMH1 as a brain repair-associated circRNA, prompting investigation into its biogenesis regulation. METHODS: We combined computational analysis of RNA-binding protein (RBP) binding sites in flanking intronic regions with transcriptomic sequencing to identify potential circSCMH1 regulators. Molecular biology experiments including RNA immunoprecipitation and functional assays were performed to validate the interaction between candidate RBPs and circSCMH1 precursor sequences. RESULTS: Polypyrimidine tract binding protein 1 (PTBP1) was identified as a key regulator binding specifically to the 800-882 segment at the 3' end of circSCMH1's flanking intron. This binding event inhibited back-splicing and reduces circSCMH1 production. Functional studies demonstrated that PTBP1-mediated suppression of circSCMH1 exacerbates post-stroke brain injury. CONCLUSIONS: Our study reveals a novel molecular mechanism whereby PTBP1 regulates circSCMH1 biogenesis through suppression of back-splicing. These findings advance understanding of circRNA regulatory networks and suggest potential therapeutic targets for stroke recovery.