Engrailed 1 coordinates cytoskeletal reorganization to induce myofibroblast differentiation

Area of Science:

• Fibrosis research
• Molecular biology
• Dermatology

Background:

• Fibrotic diseases like systemic sclerosis (SSc) involve fibroblast activation.
• Transforming growth factor-β (TGFβ) is a critical mediator of this activation.
• The specific molecular mechanisms amplifying TGFβ signaling in SSc fibroblasts require further elucidation.

Purpose of the Study:

• To investigate the role of Engrailed 1 (EN1) in fibroblast activation and myofibroblast differentiation in SSc.
• To characterize EN1 as a potential molecular amplifier of TGFβ signaling.
• To explore EN1's downstream effects on gene expression and cellular functions relevant to fibrosis.

Main Methods:

• Analysis of EN1 reexpression in SSc patient skin fibroblasts.
• Investigating TGFβ-induced EN1 expression via SMAD3 signaling.
• RNA sequencing to identify EN1-regulated genes.
• Chromatin immunoprecipitation sequencing (ChIP-seq) for EN1 and SP1 transcription factors.
• Functional assays in fibroblast cultures and in vitro skin models.
• Fibroblast-specific En1 knockout mouse models.

Main Results:

• EN1 is reexpressed in SSc fibroblasts and acts as a molecular amplifier of TGFβ signaling.
• TGFβ induces EN1 expression in a SMAD3-dependent manner, and EN1 mediates TGFβ's profibrotic effects.
• EN1 promotes a profibrotic gene expression profile linked to cytoskeleton organization and ROCK activation.
• EN1 modulates SP1 transcription factor activity, influencing gene expression.
• EN1 coordinates ROCK activity and cytoskeleton remodeling during myofibroblast differentiation.
• Fibroblast-specific En1 knockout mice show reduced myofibroblast transition and partial protection from skin fibrosis.

Conclusions:

• EN1 is a key mediator and amplifier of TGFβ signaling in SSc myofibroblast differentiation.
• EN1's regulation of cytoskeleton and ROCK pathways contributes to the profibrotic phenotype.
• Targeting EN1 may offer a novel therapeutic strategy for treating SSc and other fibrotic diseases.