Development of BODIPY FL SNS 032 as a Versatile Probe for Constitutive Androstane Receptor and Multiple Kinases

Human
constitutive androstane receptor (hCAR) regulates xenobiotic
metabolism. Its large and flexible ligand binding pocket can accommodate
structurally diverse compounds. An assay for characterizing the binding
of ligands to hCAR is needed but has not been reported. Here, we first
discovered the promiscuous kinase inhibitor SNS-032 and its derivative
THAL-SNS-032 as binders of hCAR, then developed BODIPY FL SNS 032
(14) as a high-affinity hCAR fluorescent probe (Kd: 300 ± 30 nM) in a TR-FRET binding assay
and used it to characterize hCAR ligands for their competitive binding
activities. BODIPY FL SNS 032 also displayed high binding affinities
to multiple kinases, such as hGSK3A (Kd: 4.5 ± 0.2 nM), hCDK9/CycT1 (Kd: 5.1 ± 0.6 nM), hMAPK15 (Kd: 340
± 20 nM), hCASK (Kd: 550 ± 30
nM), and hCAMKK2 (Kd: 530 ± 40 nM).
BODIPY FL SNS 032 is therefore a versatile probe for hCAR and multiple
kinases.