O-GlcNAc transferase regulates collagen deposition and fibrosis resolution in idiopathic pulmonary fibrosis

Front Immunol. 2024 Apr 11:15:1387197. doi: 10.3389/fimmu.2024.1387197. eCollection 2024.

Abstract

Background: Idiopathic pulmonary fibrosis (IPF) is a chronic pulmonary disease that is characterized by an excessive accumulation of extracellular matrix (ECM) proteins (e.g. collagens) in the parenchyma, which ultimately leads to respiratory failure and death. While current therapies exist to slow the progression, no therapies are available to resolve fibrosis.

Methods: We characterized the O-linked N-Acetylglucosamine (O-GlcNAc) transferase (OGT)/O-GlcNAc axis in IPF using single-cell RNA-sequencing (scRNA-seq) data and human lung sections and isolated fibroblasts from IPF and non-IPF donors. The underlying mechanism(s) of IPF were further investigated using multiple experimental models to modulate collagen expression and accumulation by genetically and pharmacologically targeting OGT. Furthermore, we hone in on the transforming growth factor-beta (TGF-β) effector molecule, Smad3, by co-expressing it with OGT to determine if it is modified and its subsequent effect on Smad3 activation.

Results: We found that OGT and O-GlcNAc levels are upregulated in patients with IPF compared to non-IPF. We report that the OGT regulates collagen deposition and fibrosis resolution, which is an evolutionarily conserved process demonstrated across multiple species. Co-expression of OGT and Smad3 showed that Smad3 is O-GlcNAc modified. Blocking OGT activity resulted in decreased phosphorylation at Ser-423/425 of Smad3 attenuating the effects of TGF-β1 induced collagen expression/deposition.

Conclusion: OGT inhibition or knockdown successfully blocked and reversed collagen expression and accumulation, respectively. Smad3 is discovered to be a substrate of OGT and its O-GlcNAc modification(s) directly affects its phosphorylation state. These data identify OGT as a potential target in pulmonary fibrosis resolution, as well as other diseases that might have aberrant ECM/collagen accumulation.

Keywords: IPF; O-GlcNAc; OGT; Smad3; collagen; fibrosis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Collagen* / metabolism
  • Fibroblasts / metabolism
  • Humans
  • Idiopathic Pulmonary Fibrosis* / metabolism
  • Idiopathic Pulmonary Fibrosis* / pathology
  • Lung / metabolism
  • Lung / pathology
  • Male
  • Mice
  • N-Acetylglucosaminyltransferases* / genetics
  • N-Acetylglucosaminyltransferases* / metabolism
  • Smad3 Protein / metabolism

Substances

  • N-Acetylglucosaminyltransferases
  • Collagen
  • O-GlcNAc transferase
  • Smad3 Protein
  • SMAD3 protein, human
  • OGT protein, human

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. NIH R01HL152246 to JB; NIH R00HL131866 to JB; NHLBI T32HL134640 to SV; CCTS TL1TR003106 to SV.