SARS coronavirus papain-like protease induces Egr-1-dependent up-regulation of TGF-β1 via ROS/p38 MAPK/STAT3 pathway

Sci Rep. 2016 May 13:6:25754. doi: 10.1038/srep25754.

Abstract

SARS coronavirus (SARS-CoV) papain-like protease (PLpro) has been identified in TGF-β1 up-regulation in human promonocytes (Proteomics 2012, 12: 3193-205). This study investigates the mechanisms of SARS-CoV PLpro-induced TGF-β1 promoter activation in human lung epithelial cells and mouse models. SARS-CoV PLpro dose- and time-dependently up-regulates TGF-β1 and vimentin in A549 cells. Dual luciferase reporter assays with TGF-β1 promoter plasmids indicated that TGF-β1 promoter region between -175 to -60, the Egr-1 binding site, was responsible for TGF-β1 promoter activation induced by SARS-CoV PLpro. Subcellular localization analysis of transcription factors showed PLpro triggering nuclear translocation of Egr-1, but not NF-κB and Sp-1. Meanwhile, Egr-1 silencing by siRNA significantly reduced PLpro-induced up-regulation of TGF-β1, TSP-1 and pro-fibrotic genes. Furthermore, the inhibitors for ROS (YCG063), p38 MAPK (SB203580), and STAT3 (Stattic) revealed ROS/p38 MAPK/STAT3 pathway involving in Egr-1 dependent activation of TGF-β1 promoter induced by PLpro. In a mouse model with a direct pulmonary injection, PLpro stimulated macrophage infiltration into lung, up-regulating Egr-1, TSP-1, TGF-β1 and vimentin expression in lung tissues. The results revealed that SARS-CoV PLpro significantly triggered Egr-1 dependent activation of TGF-β1 promoter via ROS/p38 MAPK/STAT3 pathway, correlating with up-regulation of pro-fibrotic responses in vitro and in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • A549 Cells
  • Animals
  • Disease Models, Animal
  • Early Growth Response Protein 1 / metabolism*
  • Epithelial Cells / metabolism
  • Fibrosis
  • Gene Silencing / drug effects
  • Glial Fibrillary Acidic Protein / metabolism
  • Humans
  • Lung / cytology
  • Mice, Inbred BALB C
  • Models, Biological
  • NF-kappa B / metabolism
  • Papain / pharmacology*
  • Promoter Regions, Genetic / genetics
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / metabolism
  • Reactive Oxygen Species / metabolism*
  • STAT3 Transcription Factor / metabolism*
  • Severe acute respiratory syndrome-related coronavirus / enzymology*
  • Signal Transduction / drug effects
  • Sp1 Transcription Factor / metabolism
  • Thrombospondin 1 / metabolism
  • Transforming Growth Factor beta1 / biosynthesis
  • Transforming Growth Factor beta1 / genetics
  • Transforming Growth Factor beta1 / metabolism*
  • Up-Regulation / drug effects*
  • Vimentin / metabolism
  • p38 Mitogen-Activated Protein Kinases / metabolism*

Substances

  • EGR1 protein, human
  • Early Growth Response Protein 1
  • Glial Fibrillary Acidic Protein
  • NF-kappa B
  • RNA, Messenger
  • RNA, Small Interfering
  • Reactive Oxygen Species
  • STAT3 Transcription Factor
  • Sp1 Transcription Factor
  • Thrombospondin 1
  • Transforming Growth Factor beta1
  • Vimentin
  • p38 Mitogen-Activated Protein Kinases
  • Papain