TGF-β1 signaling regulates mouse hepatic stellate cell differentiation via the Jagged1/Notch pathway

Aims: We tested whether transforming growth factor beta 1 (TGF-beta 1) signaling plays an important role in hepatic stellate cell differentiation fate and investigated the role of Jagged1/Notch in this process. Materials and methods: TGF-beta 1 was overexpressed and transforming growth factor receptor 1 (TGF-beta-R1) was knocked down by a lentiviral vector in mouse hepatic stellate cells (mHSCs). Transfection efficiency was assessed with immunofluorescence, quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and western blotting. The downstream genes alpha-smooth muscle actin (alpha-SMA), Jagged1 and the differentiation markers alpha-fetoprotein (AFP), albumin (ALB), cytokeratin19 (CK19), SRY (sex determining region Y)-box 9 (SOX9), and hairy and enhancer of split-1 (Hes1) were measured with qRT-PCR and western blotting. Key findings: SpHBLV-CMVIE-TGF-beta 1, pHBLV-CMVIE-GFP, pHBLV-U6-TGF-beta-R1 shRNA, and pHBLV-U6-RFP were successfully transfected. Over-expression of the TGF-beta 1 gene caused mHSCs to transform into myofibroblasts (MFs) and expression of Jagged1 and cholangiocyte markers (CK19, SOX9, Hes1) were significantly upregulated (P < 0.01). Importantly, after blocking TGF-beta 1 signaling via gene silencing, expression of Jagged1 was much reduced, but the mature hepatocyte marker (ALB) was obviously increased. In addition, AFP, a hepatic stem cell marker, was expressed at the highest level in the control groups. Significance: Our findings emphasize that the TGF-beta 1 signaling pathway regulates expression of Jagged1 in mHSCs which is associated with transformation of mHSCs into MFs, thus demonstrating a novel mechanism via which TGF-beta 1 signaling controls the differentiation fate of mHSCs through regulation of the Jagged1/Notch pathway.