Identification of a chemical probe for lipid kinase phosphatidylinositol-5-phosphate 4-kinase gamma (PI5P4Kγ)

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Phosphatidylinositol-5-phosphate 4-kinase gamma (PI5P4Kγ) is a human lipid kinase implicated in inflammation, immunity, cancer, and heart failure.
• Developing specific chemical tools is crucial for understanding PI5P4Kγ's complex biological functions.

Purpose of the Study:

• To design and validate a potent, selective, and cell-active inhibitor for human PI5P4Kγ.
• To characterize the inhibitor's binding mechanism and cellular effects.

Main Methods:

• Utilized a PI5P4Kγ NanoBRET assay for structure-activity relationship (SAR) studies and inhibitor design.
• Employed orthogonal assay formats and ATP titration to determine binding site.
• Conducted kinome-wide profiling and off-target screening for selectivity assessment.
• Investigated cellular effects in MCF-7 breast cancer cells, including mTORC1 signaling.

Main Results:

• Successfully designed and evaluated a selective PI5P4Kγ inhibitor (compound 2) and a negative control (compound 4).
• Compound 2 demonstrated binding within the ATP active site of PI5P4Kγ.
• Kinome-wide profiling confirmed the high selectivity of compound 2.
• In MCF-7 cells, compound 2 treatment led to increased mTORC1 signaling, indicating activation of a negative feedback loop.

Conclusions:

• Compound 2 serves as a valuable chemical probe for studying PI5P4Kγ.
• The inhibitor's cellular activity validates its role in activating a known PI5P4Kγ-mediated feedback pathway.
• This research provides a critical tool for further investigation into PI5P4Kγ's involvement in disease pathogenesis.