A-769662

A-769662 is a potent activator of AMPK with EC50 value of 0.8 μM in vitro[1].

AMPK(AMP-activated protein kinase) is a serine/threonine protein kinase which is formed by three proteins: α,β and γ subunits. They play important roles in both the activity and stabilities of AMPK. AMPK functions as sensors of cellular energy by detecting and reacting to the change of AMP: ATP ratio. AMPK plays an important role in regulating intracellular energy metabolism. AMPK inhibits ATP-consuming pathways containing cholesterol synthesis, fatty acid synthesisand gluconeogenesis. AMPK stimulates fatty acid oxidation and glycolysis which are ATP-generating processes. AMPK inhibits gluconeogenesis by suppressing the expression of glucose-6-phosphatase and PEPCK wich are two key gluconeogenic enzymes.[1]

A-769662 belongs to the thienopyridone family. It activates the activity of purified AMPK from diffrent tissues with a dose-dependent manner. A-769662 activated the activity of AMPK extracted from human embryonic kidney cells (HEKs), rat muscle, or rat heart with EC50 values of 1.1 mM, 1.9 mM, or 2.2mM, respectively. A-769662 inhibited the synthesis of fatty acid with IC50 value of 3.2mM in primary rat hepatocytes.[1] A769662 also has inhibition effect on the 26S proteasome with an AMPK-independent mechanism. A769662 does not inhibit the proteolytic activities of the 20S core subunit which is a novel mechanism. A769662 can cause the arrest of cell cycle by inhibiting the 26S proteasome[2]. A-769662 activates AMPK in an allosterically manner. It also inhibits Thr-172 dephosphorylation of AMPK.[3]

In mice treated with dose of 30mg/kg, A-769662 decreased the expression of FAS, G6Pase, and PEPCK in liver of. It also lowered plasma glucose by 40% and reduced body weight gain.[1]

References:
[1].  Cool B, Zinker B, Chiou W, Kifle L, Cao N, Perham M, Dickinson R, Adler A, Gagne G, Iyengar R et al: Identification and characterization of a small molecule AMPK activator that treats key components of type 2 diabetes and the metabolic syndrome. Cell Metab 2006, 3(6):403-416.
[2].  Moreno D, Knecht E, Viollet B, Sanz P: A769662, a novel activator of AMP-activated protein kinase, inhibits non-proteolytic components of the 26S proteasome by an AMPK-independent mechanism. FEBS Lett 2008, 582(17):2650-2654.
[3].  Sanders MJ, Ali ZS, Hegarty BD, Heath R, Snowden MA, Carling D: Defining the mechanism of activation of AMP-activated protein kinase by the small molecule A-769662, a member of the thienopyridone family. J Biol Chem 2007, 282(45):32539-32548.

AMP-activated protein kinase (AMPK) activator A-769662 increases intracellular calcium and ATP release from astrocytes in an AMPK-independent manner.[Pubmed:28211632]

Diabetes Obes Metab. 2017 Jul;19(7):997-1005.

AIM: To test the hypothesis that, given the role of AMP-activated protein kinase (AMPK) in regulating intracellular ATP levels, AMPK may alter ATP release from astrocytes, the main sources of extracellular ATP (eATP) within the brain. MATERIALS AND METHODS: Measurements of ATP release were made from human U373 astrocytoma cells, primary mouse hypothalamic (HTAS) and cortical astrocytes (CRTAS) and wild-type and AMPK alpha1/alpha2 null mouse embryonic fibroblasts (MEFs). Cells were treated with drugs known to modulate AMPK activity: A-769662, AICAR and metformin, for up to 3 hours. Intracellular calcium was measured using Fluo4 and Fura-2 calcium-sensitive fluorescent dyes. RESULTS: In U373 cells, A-769662 (100 muM) increased AMPK phosphorylation, whereas AICAR and metformin (1 mM) induced a modest increase or had no effect, respectively. Only A-769662 increased eATP levels, and this was partially blocked by AMPK inhibitor Compound C. A-769662-induced increases in eATP were preserved in AMPK alpha1/alpha2 null MEF cells. A-769662 increased intracellular calcium in U373, HTAS and CRTAS cells and chelation of intracellular calcium using BAPTA-AM reduced A-769662-induced eATP levels. A-769662 also increased ATP release from a number of other central and peripheral endocrine cell types. CONCLUSIONS: AMPK is required to maintain basal eATP levels but is not required for A-769662-induced increases in eATP. A-769662 (>50 muM) enhanced intracellular calcium levels leading to ATP release in an AMPK and purinergic receptor independent pathway.

A-769662, a direct AMPK activator, attenuates lipopolysaccharide-induced acute heart and lung inflammation in rats.[Pubmed:26820069]

Mol Med Rep. 2016 Mar;13(3):2843-9.

Activation of AMPactivated protein kinase (AMPK) has been indicated to produce an antiinflammatory effect through the suppression of tolllike receptor (TLR) activity. In the present study, the investigation was designed to identify the effect of A769662, a direct activator of AMPK on lipopolysaccharide (LPS)induced acute lung and heart inflammation in rats. To induce inflammation, an intraperitoneal injection of LPS (0.5 mg/kg) was administered to Wistar rats. The inflammatory parameters and AMPK phosphorylation were then measured 9 h later. For the treatment group, A769662 (10 mg/kg) was administrated intraperitoneally immediately prior to LPS injection. The results demonstrated that A769662 attenuated the LPSinduced acute inflammation in the heart and lung tissue, as indicated by the significant reduction in myeloperoxidase activity (P<0.001) and inhibition of tissue damage. This was associated with a significant reduction in tumor necrosis factoralpha serum levels (P<0.01) and peripheral neutrophils (P<0.001). Furthermore, A769662 enhanced AMPK phosphorylation and downregulated the expression of MyD88, a TLR adaptor protein, in the heart tissue. Despite the antiinflammatory effect of A769662 on LPSinduced inflammation in the lung tissue, the drug produced no effect on the MyD88 expression levels or AMPK phosphorylation in the tissue. The results of the present study suggested that the administration of A769662 results in an antiinflammatory effect in the LPSinduced model of inflammation in rats. The antiinflammatory activity was demonstrated in the heart and lung tissues and the effect on the cardiac tissue was indicated to be a result of AMPK activation, involving the suppression of TLRs.

AMPK Activation by A-769662 Controls IL-6 Expression in Inflammatory Arthritis.[Pubmed:26474486]

PLoS One. 2015 Oct 16;10(10):e0140452.

OBJECTIVE: AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase critically involved in the regulation of cellular energy homeostasis. It is a central regulator of both lipid and glucose metabolism. Many studies have suggested that AMPK activation exert significant anti-inflammatory and immunosuppressive effects. In this study, we assessed whether targeted activation of AMPK inhibits inflammatory arthritis in vivo. METHODS: We tested the effect of A-769662, a specific AMPK agonist (60mg/kg/bid) in mouse models of antigen-induced arthritis (AIA) and passive K/BxN serum-induced arthritis. The passive K/BxN serum-induced arthritis model was also applied to AMPKalpha1-deficient mice. Joints were harvested and subjected to histological analysis. IL-6 expression was measured in both joint tissues and sera by ELISA. The effect of A-769662 on bone marrow derived macrophage (BMDM) response to stimulation with TLR2 and TLR4 agonists was tested in vitro. RESULTS: AMPK activation by A-769662 reduced inflammatory infiltration and joint damage in both mouse models. IL-6 expression in serum and arthritic joints was significantly decreased in A-769662-treated mice. AMPKalpha1 deficient mice mildly elicited an increase of clinical arthritis. IL-6 expression at both mRNA and protein levels, phosphorylation of p65 NF-kappaB and MAPK phosphorylation were inhibited by A-769662 in BMDMs stimulated with either TLR2 or TLR4 agonists. CONCLUSIONS: AMPK activation by specific AMPK agonist A-769662 suppressed inflammatory arthritis in mice as well as IL-6 expression in serum and arthritic joints. These data suggest that targeted activation of AMPK has a potential to be an effective therapeutic strategy for IL-6 dependent inflammatory arthritis.

Effect of A-769662, a direct AMPK activator, on Tlr-4 expression and activity in mice heart tissue.[Pubmed:28096963]

Iran J Basic Med Sci. 2016 Dec;19(12):1308-1317.

OBJECTIVES: TLR-4 activates a number of inflammatory signaling pathways. Also, AMPK could be involved in anti-inflammatory signaling. The aim of this study was to identify whether stimulation of AMPK could inhibit LPS-induced Tlr-4 gene expression in mice hearts. MATERIALS AND METHODS: Heart AMPK activity and/or Tlr-4 expression was stimulated in different mice groups, using respectively IP injection of A-769662 (10 mg/kg) and LPS (2 mg/kg) or a combination of both agents. Moreover, compound-C (20 mg/kg), as an AMPK antagonist, was intraperitoneally co-administrated with both A-769662 and LPS in another group to investigate the role of AMPK activity on Tlr-4 regulation. After 8 hr, in addition to peripheral neutrophil cell count, myocardial p-AMPK, p-ACC as well as MyD88 protein contents and Tlr-4 expression was assessed by Western blotting and real-time qRT-PCR, respectively. TNF-alpha and IL-6 expression levels were also determined by ELISA. RESULTS: LPS induced heart Tlr-4 expression (P<0.001) associating with an increase in the myocardial MyD88 protein content (P<0.001), elevation of heart TNF-alpha (P<0.01) and IL-6 (P<0.05) concentrations, and rise in the peripheral neutrophil cell count (P<0.001). Administration of A-769662 decreased LPS-induced Tlr-4 expression (P<0.01) and alleviated peripheral neutrophil cell count (P<0.01). The inhibitory effect of A-769662 on LPS-induced Tlr-4 expression was reversed by antagonizing AMPK with compound-C (P<0.001) which reduced p-AMPK (P<0.05) and p-ACC (P<0.01) myocardial protein contents in the LPS+A-769662 group. CONCLUSION: This study demonstrated that activation of AMPK, by A-769662 agent, could inhibit Tlr-4 expression and activity, suggesting a link between AMPK and Tlr-4 in heart tissue.

Metformin activates a duodenal Ampk-dependent pathway to lower hepatic glucose production in rats.[Pubmed:25849133]

Nat Med. 2015 May;21(5):506-11.

Metformin is a first-line therapeutic option for the treatment of type 2 diabetes, even though its underlying mechanisms of action are relatively unclear. Metformin lowers blood glucose levels by inhibiting hepatic glucose production (HGP), an effect originally postulated to be due to a hepatic AMP-activated protein kinase (AMPK)-dependent mechanism. However, studies have questioned the contribution of hepatic AMPK to the effects of metformin on lowering hyperglycemia, and a gut-brain-liver axis that mediates intestinal nutrient- and hormone-induced lowering of HGP has been identified. Thus, it is possible that metformin affects HGP through this inter-organ crosstalk. Here we show that intraduodenal infusion of metformin for 50 min activated duodenal mucosal Ampk and lowered HGP in a rat 3 d high fat diet (HFD)-induced model of insulin resistance. Inhibition of duodenal Ampk negated the HGP-lowering effect of intraduodenal metformin, and both duodenal glucagon-like peptide-1 receptor (Glp-1r)-protein kinase A (Pka) signaling and a neuronal-mediated gut-brain-liver pathway were required for metformin to lower HGP. Preabsorptive metformin also lowered HGP in rat models of 28 d HFD-induced obesity and insulin resistance and nicotinamide (NA)-streptozotocin (STZ)-HFD-induced type 2 diabetes. In an unclamped setting, inhibition of duodenal Ampk reduced the glucose-lowering effects of a bolus metformin treatment in rat models of diabetes. These findings show that, in rat models of both obesity and diabetes, metformin activates a previously unappreciated duodenal Ampk-dependent pathway to lower HGP and plasma glucose levels.

Role of AMP-activated protein kinase in regulating hypoxic survival and proliferation of mesenchymal stem cells.[Pubmed:24104879]

Cardiovasc Res. 2014 Jan 1;101(1):20-9.

AIMS: Mesenchymal stem cells (MSCs) are widely used for cell therapy, particularly for the treatment of ischaemic heart disease. Mechanisms underlying control of their metabolism and proliferation capacity, critical elements for their survival and differentiation, have not been fully characterized. AMP-activated protein kinase (AMPK) is a key regulator known to metabolically protect cardiomyocytes against ischaemic injuries and, more generally, to inhibit cell proliferation. We hypothesized that AMPK plays a role in control of MSC metabolism and proliferation. METHODS AND RESULTS: MSCs isolated from murine bone marrow exclusively expressed the AMPKalpha1 catalytic subunit. In contrast to cardiomyocytes, a chronic exposure of MSCs to hypoxia failed to induce cell death despite the absence of AMPK activation. This hypoxic tolerance was the consequence of a preference of MSC towards glycolytic metabolism independently of oxygen availability and AMPK signalling. On the other hand, A-769662, a well-characterized AMPK activator, was able to induce a robust and sustained AMPK activation. We showed that A-769662-induced AMPK activation inhibited MSC proliferation. Proliferation was not arrested in MSCs derived from AMPKalpha1-knockout mice, providing genetic evidence that AMPK is essential for this process. Among AMPK downstream targets proposed to regulate cell proliferation, we showed that neither the p70 ribosomal S6 protein kinase/eukaryotic elongation factor 2-dependent protein synthesis pathway nor p21 was involved, whereas p27 expression was increased by A-769662. Silencing p27 expression partially prevented the A-769662-dependent inhibition of MSC proliferation. CONCLUSION: MSCs resist hypoxia independently of AMPK whereas chronic AMPK activation inhibits MSC proliferation, p27 being involved in this regulation.

Effects of nonmineral tissues on measurement of bone mineral content by dual-photon absorptiometry.[Pubmed:2233578]

Med Phys. 1990 Sep-Oct;17(5):905-12.

Computer simulations were performed to investigate the effects of nonmineral tissue (overlying soft tissue and nonmineral components of bone) on the measurement of bone mineral content by dual-photon absorptiometry (DPA). Selected experimental studies were performed to test the predictions of the simulations. The results indicate that variations in the composition of nonmineral tissue can significantly affect measurement precision and accuracy at the levels achievable with modern x-ray based absorptiometry systems (0.5%). Thus biological variables may limit further improvements in measurement precision and accuracy. Biological variables also can affect intercalibration of systems that use different radiation sources and/or calibration techniques.

Thienopyridone drugs are selective activators of AMP-activated protein kinase beta1-containing complexes.[Pubmed:19022182]

Chem Biol. 2008 Nov 24;15(11):1220-30.

The AMP-activated protein kinase (AMPK) is an alphabetagamma heterotrimer that plays a pivotal role in regulating cellular and whole-body metabolism. Activation of AMPK reverses many of the metabolic defects associated with obesity and type 2 diabetes, and therefore AMPK is considered a promising target for drugs to treat these diseases. Recently, the thienopyridone A769662 has been reported to directly activate AMPK by an unexpected mechanism. Here we show that A769662 activates AMPK by a mechanism involving the beta subunit carbohydrate-binding module and residues from the gamma subunit but not the AMP-binding sites. Furthermore, A769662 exclusively activates AMPK heterotrimers containing the beta1 subunit. Our findings highlight the regulatory role played by the beta subunit in modulating AMPK activity and the possibility of developing isoform specific therapeutic activators of this important metabolic regulator.

Defining the mechanism of activation of AMP-activated protein kinase by the small molecule A-769662, a member of the thienopyridone family.[Pubmed:17728241]

J Biol Chem. 2007 Nov 9;282(45):32539-48.

AMP-activated protein kinase (AMPK) plays a key role in maintaining energy homeostasis. Activation of AMPK in peripheral tissues has been shown to alleviate the symptoms of metabolic diseases, such as type 2 diabetes, and consequently AMPK is a target for treatment of these diseases. Recently, a small molecule activator (A-769662) of AMPK was identified that had beneficial effects on metabolism in ob/ob mice. Here we show that A-769662 activates AMPK both allosterically and by inhibiting dephosphorylation of AMPK on Thr-172, similar to the effects of AMP. A-769662 activates AMPK harboring a mutation in the gamma subunit that abolishes activation by AMP. An AMPK complex lacking the glycogen binding domain of the beta subunit abolishes the allosteric effect of A-769662 but not the allosteric activation by AMP. Moreover, mutation of serine 108 to alanine, an autophosphorylation site within the glycogen binding domain of the beta1 subunit, almost completely abolishes activation of AMPK by A-769662 in cells and in vitro, while only partially reducing activation by AMP. Based on our results we propose a model for activation of AMPK by A-769662. Importantly, this model may provide clues for understanding the mechanism by which AMP leads to activation of AMPK, which in turn may help in the identification of other AMPK activators.