MicroRNA-30d/JAG1 axis modulates pulmonary fibrosis through Notch signaling pathway

Pulmonary fibrosis (PF) is a fibroproliferative disease which can finally end up fatal lung failure. PF is characterized by abnormal proliferation of fibroblast, dysregulated fibroblast differentiation to myofibroblast and disorganized collagen and extracellular matrix (ECM) production, deposition and degradation. JAG1/Notch signaling has been reported to play a key role in tissue fibrosis including PF. Herein, we confirmed the abnormal upregulation of JAG1 mRNA expression and protein levels in PF tissue specimens; JAG1 knockdown reduced TGF-β1-induced α-SMA and Collagen I protein levels. From the aspect of miRNA regulation, we searched for candidate miRNAs which might target JAG1 to inhibit its expression. Among the selected miRNAs, miR-30d expression was downregulated in PF tissues; miR-30d overexpression attenuated TGF-β1-induced primary normal human lung fibroblast (NHLF) proliferation, as well as α-SMA and Collagen I protein levels. Through directly binding to the 3′-UTR of JAG1, miR-30d significantly inhibited JAG1 mRNA expression and protein level. Furthermore, JAG1 overexpression partially reversed the effect of miR-30d on NHLF proliferation and α-SMA and Collagen I proteins upon TGF-β1 stimulation; miR-30d could suppress TGF-β1 function on NHLFs through blocking JAG1/Notch signaling. Rescuing miR-30d expression to suppress TGF-β1-induced activation of JAG1/Notch signaling may present a promising strategy for PF treatment.