FXR DUBTAC IN-1

FXRDUBTAC IN-1 (compound D11) is a deubiquitinase-targeting chimera (DUBTAC) designed to target FXR, with a Ka value of 2.12e-5 M. This compound recruits the deubiquitinase OTUB1 to form a ternary complex with FXR, reducing FXR's polyubiquitination levels. It prevents FXR degradation via the ubiquitin-proteasome pathway, thereby increasing FXR protein levels. FXRDUBTAC IN-1 is used in the study of cholestatic liver injury.

FXR DUBTAC IN-1 (compound D11) significantly increases FXR protein expression in HepG2 cells at concentrations of 1-10 μM over a 24-hour period while maintaining 70.71% cell viability at 50 μM. The compound enhances FXR protein levels in a dose-dependent manner within a concentration range of 0.1-10 μM. When used at 1 μM, it time-dependently upregulates FXR protein, detectable as early as 1 hour with the effect persisting up to 8 hours. FXR DUBTAC IN-1 stabilizes FXR protein in HepG2 cells by promoting its deubiquitination, evidenced by decreased FXR polyubiquitination and increased protein levels. It binds to purified FXR protein with a dissociation constant (K d) of 2.12 × 10^-5 M, as determined by surface plasmon resonance. The stabilization effect of FXR DUBTAC IN-1 on FXR protein in HepG2 cells is dependent on OTUB1, as OTUB1 knockdown negates this stabilization. Additionally, FXR DUBTAC IN-1 shows good metabolic stability in mouse and rat liver microsomes, with a half-life exceeding 120 minutes in both species at a concentration of 2 μM.

FXR DUBTAC IN-1 (compound D11), administered via intraperitoneal injection once daily for 5 consecutive days at a dose of 1-2.5 mg/kg, effectively stabilizes hepatic FXR protein and provides potent, dose-dependent hepatoprotective effects against ANIT-induced cholestasis, demonstrating efficacy comparable to or exceeding that of OCA at equivalent or lower doses. Administered under the same conditions but for 3 days, FXR DUBTAC IN-1 mitigates cholestatic liver damage in an OTUB1-dependent manner, as knocking down OTUB1 completely negates its hepatoprotective effects.