Fig. 7: Metrnl regulates PDGFB release via EGR1 from hepatocytes to activate PDGFRβ signaling pathway.

ELISA-quantified PDGFB levels in culture medium (CM) (A) and mRNA expression level (B) of primary hepatocytes transfected with adenovirus-mediated Metrnl overexpression (OE-Met) and primary hepatocytes from Alb-Metrnl−/− mice (n = 3 per group). The mRNA expression (C) and Western blot images (D) and its quantification analysis (down panel) of α-SMA and Col4 in LX-2 cells after incubating CM from LO2 cells transfected with OE-Metrnl virus, and treated with or without PDGFB neutralization antibody (PDGFB-Nabs) or control IgG, which was used to block PDGFB in the CM (n = 3 per group). E A Venn diagram created by the jvenn tool to display potential transcription factors of PDGFB predicted by TF-Target Finder. F A Venn diagram showing the intersection of seven potential transcription factors (CTCF, EGR1, et.al) with RNA-Seq data from Metrnl-overexpressing LX-2 cells. G The mRNA expression of EGR1 in primary hepatocytes from C57BL/6 mice transfected with adenovirus-mediated OE-Metrnl constructs (n = 5 per group). H The mRNA expression of EGR1 in the liver from CCl4-induced mice injected with AAV-vector or AAV-Metrnl virus (n = 6 per group). Representative Western blot images (I) and quantification analysis of EGR1, also the relative mRNA expression (J) in the liver from WT and Metrnl−/− mice induced by CCl4 for 8 weeks (n = 4 per group). ELISA-quantified PDGFB levels in CM (K) and the mRNA expression levels (L) of primary hepatocytes transfected with OE-Metrnl or OE-EGR1 overexpression virus, or both viruses combined (n = 3–4 per group). M RT-qPCR analysis of PDGFB mRNA levels with EGR1 antibody or IgG antibody respectively by ChIP assay in Metrnl-knockdown or control LO2 cells (n = 3 per group). All data are mean ± SD. *P < 0.05, **P < 0.01, and ***P < 0.001.