EGF-R regulates MMP function in fibroblasts through MAPK and AP-1 pathways

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Epidermal Growth Factor Receptor (EGF-R) regulates key fibroblast functions like proliferation, migration, and invasion.
• The downstream signaling pathways linking EGF-R to these cellular responses remain incompletely understood.

Purpose of the Study:

• To elucidate the role of EGF-R and its downstream signaling in mediating matrix metalloproteinase (MMP) expression and collagen contraction in fibroblasts.
• To identify the specific signaling pathways and transcription factors involved in EGF-R-mediated fibroblast responses.

Main Methods:

• Utilized EGF-R knockout (EGF-R-/-) mouse embryonal fibroblasts and wild-type counterparts.
• Assessed MMP expression (MMP-2, -3, -14) and collagen contraction.
• Investigated the activity of Erk and Jnk pathways, including AP-1 DNA-binding and transactivation.
• Employed specific inhibitors for Jnk and Mek/Erk pathways, and utilized dominant-negative c-Jun and constitutively active Mek1 expression.

Main Results:

• EGF-R deficiency impaired basal and inducible expression of MMPs (-2, -3, -14) and collagen contraction.
• Impaired MMP expression correlated with suppressed EGF-induced Erk/Jnk activities and AP-1 function.
• Inhibition of Erk and Jnk pathways partially prevented MMP-3/-14 expression and collagen contraction.
• Dominant-negative c-Jun downregulated MMP-3 expression, while active Mek1 induced it.

Conclusions:

• The Extracellular signal-Regulated Kinase (ERK) pathway and Activator Protein-1 (AP-1) are crucial downstream effectors of EGF-R signaling in fibroblasts.
• EGF-R signaling mediates MMP expression and collagen contraction through the ERK pathway and AP-1.
• These findings clarify the molecular mechanisms by which EGF-R controls fibroblast behavior and extracellular matrix remodeling.