OncoPPi-informed discovery of mitogen-activated protein kinase kinase 3 as a novel binding partner of c-Myc

Area of Science:

• Molecular biology
• Cellular signaling
• Cancer research

Background:

• Mitogen-activated protein kinase kinase 3 (MKK3) is known to regulate inflammation, proliferation, and apoptosis via p38 signaling.
• The broader functions of MKK3 beyond p38 activation are not well understood.
• The OncoPPi network identified MKK3 as a key hub protein involved in cancer-associated gene interactions.

Purpose of the Study:

• To investigate the role of MKK3 beyond its known p38 signaling pathway.
• To identify novel protein-protein interactions involving MKK3, particularly in the context of cancer.
• To elucidate the functional consequences of MKK3 interactions with key cellular regulators.

Main Methods:

• Utilized the OncoPPi protein-protein interaction network to identify MKK3 interactors.
• Employed multiple biochemical and biophysical techniques to confirm MKK3-MYC interaction in vitro and in vivo.
• Performed computational modeling to map the interaction interface between MKK3 and MYC.
• Characterized the functional impact of MKK3 on MYC stability, transcriptional activity, and target gene expression.

Main Results:

• MKK3 directly interacts with the major oncogenic driver MYC.
• The interaction interface was mapped to MYC's helix-loop-helix domain and a novel MKK3 binding motif (MBM).
• MKK3 binding stabilizes MYC, enhances its transcriptional activity, and upregulates MYC-regulated genes.
• A synthetic MBM peptide replicated MKK3's effect on MYC activity.

Conclusions:

• MKK3 plays a dual role in cellular regulation: phosphorylating p38 and activating MYC through protein-protein interaction.
• This discovery presents a new model for MKK3 function in cell growth and cancer.
• MKK3 emerges as a potential therapeutic target for cancers driven by MYC.