Down-Regulation of CXXC5 De-Represses MYCL1 to Promote Hepatic Stellate Cell Activation

Abstract

Liver fibrosis is mediated by myofibroblasts, a specialized cell type involved in wound healing and extracellular matrix production. Hepatic stellate cells (HSC) are the major source of myofibroblasts in the fibrotic livers. In the present study we investigated the involvement of CXXC-type zinc-finger protein 5 (CXXC5) in HSC activation and the underlying mechanism. Down-regulation of CXXC5 was observed in activated HSCs compared to quiescent HSCs both in vivo and in vitro. In accordance, over-expression of CXXC5 suppressed HSC activation. RNA-seq analysis revealed that CXXC5 influenced multiple signaling pathways to regulate HSC activation. The proto-oncogene MYCL1 was identified as a novel target for CXXC5. CXXC5 bound to the proximal MYCL1 promoter to repress MYCL1 transcription in quiescent HSCs. Loss of CXXC5 expression during HSC activation led to the removal of CpG methylation and acquisition of acetylated histone H3K9/H3K27 on the MYCL1 promoter resulting in MYCL1 trans-activation. Finally, MYCL1 knockdown attenuated HSC activation whereas MYCL1 over-expression partially relieved the blockade of HSC activation by CXXC5. In conclusion, our data unveil a novel transcriptional mechanism contributing to HSC activation and liver fibrosis.

Targetable Brg1‐CXCL14 axis contributes to alcoholic liver injury by driving neutrophil trafficking

“…RNA‐seq was performed as previously described (Wu et al, 2021). Total RNA was extracted using the TRIzol reagent according to the manufacturer's protocol.…”

MKL1 fuels ROS-induced proliferation of vascular smooth muscle cells by modulating FOXM1 transcription

“…FOXM1 expression constructs [ 24 ], FOXM1 promoter-luciferase constructs [ 25 , 26 ], FLAG-tagged MKL1 expression constructs [ 27 ], and GFP-tagged E2F1 expression constructs [ 28 ] have been described previously. Mutagenesis was performed a QuikChange kit (Thermo Fisher Scientific, Waltham, MA, United States) as previously described [ 29 ]. All DNA constructs were verified by direct sequencing.…”

SIRT6 mediates MRTF-A deacetylation in vascular endothelial cells to antagonize oxLDL-induced ICAM-1 transcription

“…Whole-cell lysates were obtained by re-suspending cell pellets in the lysis buffer (50 mMTris pH 7.4, 150 mM NaCl, 1% Triton X-100) with freshly added protease inhibitor (Roche) as previously described [ 63 , 64 ]. Nuclear proteins were prepared with the NE-PER Kit (Pierce) following the manufacturer’s recommendation.…”