FRAX486

FRAX486 is a p21-activated kinase (PAK) inhibitor with IC₅₀s of 14, 33 and 39 nM for PAK1, PAK2 and PAK3, respectively. IC50 & Target: IC50: 14 nM (PAK1), 33 nM (PAK2), 39 nM (PAK3)^[2] In Vitro: In vitro kinase assays using pure enzymes reveal IC₅₀s for FRAX486 between 10-100 nM for PAK1-3, while the IC₅₀ of 779 nM for PAK4 is just below the micromolar range. For FRAX486, an EC₅₀ value of 500 nM has been reported from cells (5-50 fold higher than IC₅₀). FRAX486 (30 μM) inhibits endothelin-1 and -2 induced contractions. In WPMY-1 cells, FRAX486 (24 h) induces concentration-dependent (1-10 μM) degeneration of actin filaments. This is paralleled by attenuation of proliferation rate, being observed from 1 to 10 μM FRAX486. Cytotoxicity of FRAX486 in WPMY-1 cells is time- and concentration-dependent. FRAX486 significantly reduces the relative proliferation rate in the remaining populations of WPMY-1 cells. While 68% of solvent-treated (24 h) cells shows proliferation, proliferation rate after application of FRAX486 (1-10 μM, 24 h) ranges around 45%. FRAX486 (1-10 μM, 24 h) causes concentration-dependent degeneration of actin filaments. Actin filaments in solvent-treated control cells are arranged to bundles, forming long and thin protrusions, with elongations from adjacent cells overlapping each other. FRAX486 in concentrations of 1 μM causes partial loss of actin organization, including regressing degree of actin polymerization and degeneration of protrusions. FRAX486 in concentrations of 5 or 10 μM causes complete breakdown of filament organization, resulting in a rounded cell shape without protrusions^[1]. In Vivo: FRAX486 displays the highest penetrance of blood–brain barrier in DISC1-knockdown C57BL/6 mice. Daily administration of FRAX486, but not that of vehicle, between P35 and P60 blocks the exacerbated spine loss during adolescence. In addition to the significant blockade of spine elimination, a trend of enhanced spine generation is observed by treatment with FRAX486. FRAX486 treatment ameliorates a deficit in prepulse inhibition in adulthood^[2].