a-769662 and Insulin-Resistance

As a central regulator of metabolism, the AMP-activated protein kinase (AMPK) is an established therapeutic target for metabolic diseases. Beyond the metabolic area, the number of medical fields that involve AMPK grows continuously, expanding the potential applications for AMPK modulators. Even though indirect AMPK activators are used in the clinics for their beneficial metabolic outcome, the few described direct agonists all failed to reach the market to date, which leaves options open for novel targeting methods. As AMPK is not actually a single molecule and has different roles depending on its isoform composition, the opportunity for isoform-specific targeting has notably come forward, but the currently available modulators fall short of expectations. In this review, we argue that with the amount of available structural and ligand data, computer-based drug design offers a number of opportunities to undertake novel and isoform-specific targeting of AMPK.

Topics: AMP-Activated Protein Kinases; Animals; Brain; Computer-Aided Design; Drug Design; Enzyme Activation; Humans; Insulin Resistance; Ligands; Molecular Targeted Therapy; Neoplasms; Protein Kinase Inhibitors; Signal Transduction; Structure-Activity Relationship

This study investigated the molecular mechanism of saponarin, a flavone glucoside, in the regulation of insulin sensitivity. Saponarin suppressed the rate of gluconeogenesis and increased cellular glucose uptake in HepG2 and TE671 cells by regulating AMPK. Using an in vitro kinase assay, we showed that saponarin did not directly interact with the AMPK protein. Instead, saponarin increased intracellular calcium levels and induced AMPK phosphorylation, which was diminished by co-stimulation with STO-609, an inhibitor of CAMKKβ. Transcription of hepatic gluconeogenesis genes was upregulated by nuclear translocation of CRTC2 and HDAC5, coactivators of CREB and FoxO1 transcription factors, respectively. This nuclear translocation was inhibited by increased phosphorylation of CRTC2 and HDAC5 by saponarin-induced AMPK in HepG2 cells and suppression of CREB and FoxO1 transactivation activities in cells stimulated by saponarin. The results from a chromatin immunoprecipitation assay confirmed the reduced binding of CRTC2 on the PEPCK and G6Pase promoters. In TE671 cells, AMPK phosphorylated HDAC5, which suppressed nuclear penetration and upregulated GLUT4 transcription, leading to enhanced glucose uptake. Collectively, these results suggest that saponarin activates AMPK in a calcium-dependent manner, thus regulating gluconeogenesis and glucose uptake.

Topics: AMP-Activated Protein Kinases; Apigenin; Benzimidazoles; Biphenyl Compounds; Calcium; Calcium-Calmodulin-Dependent Protein Kinase Kinase; Cyclic AMP Response Element-Binding Protein; Enzyme Activators; Forkhead Box Protein O1; Forkhead Transcription Factors; Gluconeogenesis; Glucose; Glucose Transporter Type 4; Glucosides; Hep G2 Cells; Histone Deacetylases; Humans; Insulin Resistance; Metformin; Naphthalimides; Phosphorylation; Pyrones; Thiophenes; Transcription Factors