The discovery and the structural basis of an imidazo[4,5-b]pyridine-based p21-activated kinase 4 inhibitor

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• p21-Activated kinases (PAKs) are serine/threonine protein kinases regulating critical cellular functions including cytoskeletal dynamics, motility, proliferation, and oncogenic transformation.
• PAK dysregulation is implicated in cancer induction and metastasis, establishing PAKs as significant therapeutic targets.

Purpose of the Study:

• To discover and validate a novel imidazo[4,5-b]pyridine-based inhibitor targeting PAK4.
• To characterize the binding interaction of the identified inhibitor with PAK4.

Main Methods:

• Virtual site-directed fragment-based drug design was employed to identify potential PAK4 inhibitors.
• An inhibition assay was used to validate the inhibitory activity of the discovered compound.
• Co-crystallization of PAK4 with the inhibitor was performed to determine the binding mode.

Main Results:

• KY-04045, an imidazo[4,5-b]pyridine derivative, was identified as a PAK4 inhibitor.
• Structural analysis revealed that the pyrazole and imidazopyridine moieties of KY-04045 are crucial for interacting with the PAK4 hinge region.
• While KY-04045 exhibits weaker affinity compared to existing inhibitors, its defined binding mode provides valuable structural insights.

Conclusions:

• KY-04045 serves as a promising scaffold for the development of novel and potent imidazo[4,5-b]pyridine-based PAK4 inhibitors.
• The structural information obtained can guide further optimization efforts for enhanced therapeutic efficacy against cancers involving PAK signaling.