LncRNA SYISL promotes fibroblast myofibroblast transition via miR-23a-mediated TRIOBP regulation.

Long non-coding RNAs (lncRNAs) play critical roles in the process of lung tissue injury and repair which abnormal repair leads to disease including fibrosis, yet the physiopathology remains elusive. Here, we identified the lncRNA SYISL as a key regulator that is markedly upregulated in idiopathic pulmonary fibrosis (IPF) patients and bleomycin (BLM)-induced murine fibrotic lungs. Inhibition of SYISL significantly attenuates TGF-β1-driven fibroblast myofibroblast transition (FMT), a process confers to tissue injury repair and regeneration. Which demonstrates SYISL interaction with miR-23a function as a potent suppressor of fibrotic activation. Mechanistically, SYISL acts as a competing endogenous RNA (ceRNA) that directly binds miR-23a, thereby derepressing TRIO and F-actin binding protein (TRIOBP) via targeting its 3' untranslated region (UTR). Knockdown of TRIOBP amplifies the anti-fibrotic effects of miR-23a mimics while abolishing the pro-fibrotic activity of miR-23a inhibitors, establishing TRIOBP as a downstream effector of the SYISL/miR-23a axis. In vivo, intratracheal delivery of SYISL-targeting shRNA via adeno-associated virus (AAV) robustly reduces collagen deposition, hydroxyproline content, and expression of fibrotic markers in BLM-induced mice. Our findings elucidate a lncRNA-driven regulatory circuit in which SYISL promotes pulmonary fibrosis by sequestering miR-23a to elevate TRIOBP expression, nominating this axis as a novel therapeutic target for IPF.