p38gamma MAPK cooperates with c-Jun in trans-activating matrix metalloproteinase 9

Area of Science:

• Molecular Biology
• Cell Signaling
• Cancer Biology

Background:

• Mitogen-activated protein kinases (MAPKs) are crucial regulators of gene expression via transcription factors.
• The precise molecular mechanisms linking MAPKs to transcription factor activity remain largely undefined.
• Understanding these pathways is critical for deciphering cellular responses and disease mechanisms.

Purpose of the Study:

• To elucidate the mechanism by which p38gamma MAPK regulates transcription factor activity.
• To investigate the role of p38gamma MAPK and c-Jun in the regulation of matrix metalloproteinase 9 (MMP9) gene expression.
• To determine the involvement of this pathway in cancer cell invasion.

Main Methods:

• Investigated the interaction between p38gamma MAPK and c-Jun using biochemical assays.
• Analyzed the effect of p38gamma MAPK on c-Jun synthesis and activity.
• Examined the recruitment of p38gamma to the MMP9 promoter and its role in trans-activation.
• Assessed MMP9 expression and cell invasion in response to p38gamma manipulation.
• Correlated p38gamma and MMP9 expression in human colon cancer tissues.

Main Results:

• p38gamma MAPK phosphorylates and activates the transcription factor c-Jun.
• Activated c-Jun recruits p38gamma MAPK to the MMP9 promoter, enhancing MMP9 transcription.
• This signaling cascade leads to increased matrix metalloproteinase 9 (MMP9)-dependent cell invasion.
• The p38gamma/c-Jun/MMP9 pathway is active in human colon cancer, with coupled expression of p38gamma and MMP9.

Conclusions:

• MAPKs can function as both activators and cofactors for transcription factors, revealing a novel regulatory paradigm.
• The p38gamma MAPK-c-Jun-MMP9 axis is a key pathway driving gene expression and cell invasion.
• This pathway represents a potential therapeutic target for invasive cancers like colon cancer.