A-769662

A-769662 stimulates partially purified rat liver AMPK with EC50 with 0.8 μM. A-769662 activates AMPK purified from multiple tissues and species in a dose-responsive manner with modest variations in observed EC50s. EC50s determined for A-769662 using partially purified AMPK extracts from rat heart, rat muscle, or human embryonic kidney cells (HEKs) are 2.2 mM, 1.9 mM, or 1.1 mM, respectively. A 4 hours treatment of primary rat hepatocytes with A-769662 dose-dependently increases ACC phosphorylation, which correlated inhibition of fatty acid synthesis with IC50 of 3.2 μM. A-769662 also inhibits fatty acid sythesis in mouse hepatocytes with IC50 with 3.6 μM ^[1] A-769662 activates AMPK both allosterically and by inhibiting dephosphorylation of AMPK on Thr-172, similar to the effects of AMP. ^[2] A-769662 inhibits proteasomal function by an AMPK-independent mechanism. A-769662 affects the in vitro activity of purified 26S proteasomes but not the in vitro activity of purified 20S proteasomes. A-769662 has toxic effects on MEF cells. ^[3] A recent research shows A-769662 inhibited cell proliferation and DNA synthesis. ^[4]

Short-term treatment of normal Sprague Dawley rats with A-769662 decreases liver malonyl CoA levels and the respiratory exchange ratio, VCO2/VO2, indicating an increased rate of whole-body fatty acid oxidation. Treatment of ob/ob mice with 30 mg/kg b.i.d. A-769662 decreases hepatic expression of PEPCK, G6Pase, and FAS, lowers plasma glucose by 40%, reduced body weight gain and significantly decreases both plasma and liver triglyceride levels. ^[1]

• 96-well AMPK assay

  AMPK activity is measured by monitoring phosphorylation of the SAMS peptide substrate (20 μM in standard assays and 100 μM in additivity assays) following a previously described protocol (Anderson et al., 2004). To determine whether A-769662-induced AMPK activation occurs in a reversible manner, AMP or A-769662 are preincubated with rat liver AMPK for 10 minutes at 20 times standard assay concentrations prior to dilution and measurement of AMPK activity.

  ^[1]

• Cell lines

  MEF cells

• Concentrations

  300 μM

• Incubation Time

  24 hours

• Method

  Cell viability of MEF cells treated or not with A-769662 is performed as follows: cells are harvested by trypsinization and incubated with 0.5 mg/mL RNase and 50 μg/mL propidium iodine at room temperature in the dark; cell viability is analyzed by flow cytometry using a FACScanto flow cytometer, using an excitation laser at 488 nm and a propidium iodine fluorescence detection at 600 nm. To determine the proportion of cells in each phase of the cell cycle, cells are harvested by trypsinization, collected by centrifugation, washed in PBS and fixed overnight in 80% ethanol at -20 °C. Subsequently, these fixed cells are centrifuged to remove the fixative and incubated for 20 minutes in the dark at room temperature in PBS containing 0.5 mg/mL RNase and 50 μg/mL propidium iodine. Flow cytometry analysis is performed as above. The proportion of cells in G1, S, and G2 is determined using the MODFIT program. Cell culture pictures are taken at the indicated times using a camera coupled to an inverted microscope with a 20 × objective.

• Animal Models

  Sprague Dawley rats

• Dosages

  30 mg/kg

• Administration

  Administered via i.p.