PAK4 Methylation by SETD6 Promotes the Activation of the Wnt/β-Catenin Pathway

Area of Science:

• Molecular Biology
• Epigenetics
• Cell Signaling

Background:

• Lysine methylation of non-histone proteins is an emerging post-translational modification regulating diverse cellular processes.
• While less characterized than phosphorylation or acetylation, the repertoire of methylated proteins is rapidly expanding.
• p21-activated kinase 4 (PAK4) is implicated in various cellular functions, including signaling pathways.

Purpose of the Study:

• To identify novel substrates of the protein lysine methyltransferase SETD6.
• To elucidate the role of SETD6-mediated methylation in the regulation of the Wnt/β-catenin signaling pathway.
• To investigate the interaction between SETD6, PAK4, and β-catenin.

Main Methods:

• In vitro methylation assays to confirm SETD6 activity on PAK4.
• Chromatin-based methylation analysis in cellular systems.
• Depletion studies (e.g., siRNA or shRNA) to assess the functional impact of SETD6.
• Co-immunoprecipitation assays to evaluate protein-protein interactions.
• Quantitative PCR or reporter assays to measure Wnt/β-catenin target gene transcription.

Main Results:

• SETD6 was identified as a methyltransferase for PAK4, catalyzing methylation both in vitro and on chromatin.
• Depletion of SETD6 led to impaired activation of Wnt/β-catenin target genes.
• SETD6 enhances the physical interaction between PAK4 and β-catenin.
• Increased PAK4-β-catenin interaction resulted in elevated transcription of β-catenin target genes.

Conclusions:

• SETD6 methylates PAK4, establishing a novel regulatory mechanism within the Wnt/β-catenin signaling cascade.
• SETD6 acts as a key mediator, promoting PAK4-β-catenin interaction and subsequent target gene activation.
• This study uncovers a new layer of epigenetic regulation in Wnt/β-catenin signaling, expanding our understanding of SETD6 biology.