AZD1080

AZD1080 is a selective, orally active, brain permeable GSK3 inhibitor, inhibits human GSK3α and GSK3β with a K_i of 6.9 nM and 31 nM, respectively, shows >14-fold selectivity against cdk2, cdk5, cdk1 and Erk2. AZD1080 inhibits tau phosphorylation in cells expressing human tau, with IC50 of 324 nM. ^[1]

AZD1080 inhibits tau phosphorylation in rat brain after oral dministration, with brain/plasma exposure ratio of 0.5 – 0.8 at peak concentrations. AZD1080 reverses cognitive deficits and rescues dysfunctional synapses in mice. Acute oral treatment with AZD1080 inhibits peripheral GSK3 activity, produces a dose-dependent reduction of the phosphorylated to total glycogen synthase (GS) ratio, with a mean maximal inhibitory effect of 49% at the highest dose (10 μmol/kg) at 2 h after dosing. ^[1]

• Kinase Assay

  GSK3 scintillation proximity assay is done. The competition experiments are carried out in duplicate with 10 concentrations of the inhibitor in clear-bottomed microtiter plates. The biotinylated peptide substrate biotin-AAEELDSRAGS(PO3H2)PQL, is added at a final concentration of 2 μM in an assay buffer containing 6 milliunits of recombinant human GSK3 (equal mix of both α and β), 12 mM MOPS, pH 7.0, 0.3 mM EDTA, 0.01% β-mercaptoethanol, 0.004% Brij 35, 0.5% glycerol, and 0.5 μg of bovine serum albumin/25 μl and preincubated for 10–15 min. The reaction is initiated by the addition of 0.04 μCi of [γ-³³P]ATP and unlabeled ATP in 50 mM Mg(Ac)₂ to a final concentration of 1 μM ATP and assay volume of 25 μl. Blank controls without peptide substrate are used. After incubation for 20 min at room temperature, each reaction is terminated by the addition of 25 μl of stop solution containing 5 mM EDTA, 50 μM ATP, 0.1% Triton X-100, and 0.25 mg of streptavidin-coated SPA beads corresponding to 35 pmol of binding capacity. After 6 h the radioactivity is determined in a liquid scintillation counter.

• Cell lines

  3T3 fibroblasts stably expressing 4-repeat human tau

• Concentrations

  ~20mM

• Incubation Time

  0-8 h

• Method

  3T3 fibroblasts are engineered to stably express four-repeat tau protein. These cells have high endogenous levels of GSK3 that is able to phosphorylate tau protein constitutively. This phosphorylation is inhibited by LiCl. After treatment with different compounds, cultures are washed twice with 5 mM MgCl₂-PBS.  The samples are homogenized at 4 °C, and protein content is determined by Bradford method. Total protein (25 μg) is electrophoresed on 10% SDS-PAGE gel and transferred to a nitrocellulose membrane. The experiments are performed using the following primary antibodies: tau Ser(P)-396, 1:1000; Tau5, 1:1000; and anti-GSK3β, 1:1000. The filters are incubated with the antibody at 4 °C overnight in 5% nonfat dried milk. A secondary antibody (1:5000), followed by ECL detection reagents are used for immunodetection. Quantitation of immunoreactivity is performed by densitometric scanning.

• Animal Models

  C57BL/6 mice

• Dosages

  3 or 10 μmol/kg, 6 mL/kg

• Administration

  oral gavage