sto-609 and dorsomorphin

We reported recently that activators of AMP-activated protein kinase (AMPK) slow the rundown of current evoked by the D2 autoreceptor agonist quinpirole in rat substantia nigra compacta (SNC) dopamine neurons. The present study examined the effect of AMPK on current generated by dopamine, which unlike quinpirole, is a substrate for the dopamine transporter (DAT). Using whole-cell patch-clamp, we constructed current-voltage (I-V) plots while superfusing brain slices with dopamine (100 μM) for 25 min. Two minutes after starting superfusion, dopamine evoked a peak current with an average slope conductance of 0.97 nS and an estimated reversal potential (E

Topics: AMP-Activated Protein Kinases; Animals; Benzamides; Benzazepines; Benzimidazoles; Biphenyl Compounds; Dopamine; Dopamine D2 Receptor Antagonists; Dopamine Plasma Membrane Transport Proteins; Dopaminergic Neurons; Naphthalimides; Pars Compacta; Patch-Clamp Techniques; Piperazines; Pyrazoles; Pyrimidines; Pyrones; Pyrrolidines; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Sulpiride; Thiophenes

Triptolide, a triterpene extracted from the Chinese herb Tripterygium wilfordii, has been reported to exert multiple bioactivities, including immunosuppressive, anti‑inflammatory and anticancer effects. Although the anticancer effect of triptolide has attracted significant attention, the specific anticancer mechanism in non‑small‑cell lung cancer (NSCLC) remains unclear. The present study aimed to investigate the anticancer effect of triptolide in the H1395 NSCLC cell line and to determine its mechanism of action. The results revealed that triptolide significantly inhibited the cell viability of NSCLC cells in a dose‑dependent manner, which was suggested to be through inducing apoptosis. In addition, triptolide was revealed to activate the calcium (Ca2+)/calmodulin‑dependent protein kinase kinase β (CaMKKβ)/AMP‑activated protein kinase (AMPK) signaling pathway by regulating the intracellular Ca2+ concentration levels, which increased the phosphorylation levels of AMPK and reduced the phosphorylation levels of AKT, ultimately leading to apoptosis. The CaMKKβ blocker STO‑609 and the AMPK blocker Compound C significantly inhibited the apoptosis‑promoting effect of triptolide. In conclusion, the results of the present study suggested that triptolide may induce apoptosis through the CaMKKβ‑AMPK signaling pathway and may be a promising drug for the treatment of NSCLC.

Topics: AMP-Activated Protein Kinases; Apoptosis; Benzimidazoles; Calcium; Calcium-Calmodulin-Dependent Protein Kinase Kinase; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Diterpenes; Epoxy Compounds; Humans; Lung Neoplasms; Naphthalimides; Phenanthrenes; Phosphorylation; Pyrazoles; Pyrimidines; Signal Transduction

This study aims to investigate the effects of ramipril (RPL) on endothelial dysfunction associated with diabetes mellitus using cultured human aortic endothelial cells (HAECs) and a type 2 diabetic animal model. The effect of RPL on vasodilatory function in fat-fed, streptozotocin-treated rats was assessed. RPL treatment of 8 weeks alleviated insulin resistance and inhibited the decrease in endothelium-dependent vasodilation in diabetic rats. RPL treatment also reduced serum advanced glycation end products (AGE) concentration and rat aorta reactive oxygen species formation and increased aorta endothelium heme oxygenase-1 (HO-1) expression. Exposure of HAECs to high concentrations of glucose induced prolonged oxidative stress, apoptosis, and accumulation of AGEs. These effects were abolished by incubation of ramiprilat (RPT), the active metabolite of RPL. However, treatment of HAECs with STO-609, a CaMKKβ (Ca(2+)/calmodulin-dependent protein kinase kinase-β) inhibitor; compound C, an AMPK (AMP-activated protein kinase) inhibitor; and Zn(II)PPIX, a selective HO-1 inhibitor, blocked these beneficial effects of RPT. In addition, RPT increased nuclear factor erythroid 2-related factor-2 (Nrf-2) nuclear translocation and activation in a CaMKKβ/AMPK pathway-dependent manner, leading to increased expression of the Nrf-2-regulated antioxidant enzyme, HO-1. The inhibition of CaMKKβ or AMPK by pharmaceutical approach ablated RPT-induced HO-1 expression. Taken together, RPL ameliorates insulin resistance and endothelial dysfunction in diabetes via reducing oxidative stress. These effects are mediated by RPL activation of CaMKK-β, which in turn activates the AMPK-Nrf-2-HO-1 pathway for enhanced endothelial function.

Topics: AMP-Activated Protein Kinases; Animals; Aorta; Apoptosis; Benzimidazoles; Calcium-Calmodulin-Dependent Protein Kinase Kinase; Cells, Cultured; Diabetes Mellitus, Experimental; Endothelial Cells; Enzyme Activation; Glucose; Glycation End Products, Advanced; Heme Oxygenase (Decyclizing); Humans; Insulin Resistance; Male; Naphthalimides; NF-E2-Related Factor 2; Oxidative Stress; Phosphorylation; Protein Kinase Inhibitors; Protoporphyrins; Pyrazoles; Pyrimidines; Ramipril; Rats; Reactive Oxygen Species; Signal Transduction; Vasodilation

AMP-activated protein kinase (AMPK) serves as an energy sensor and is considered a promising drug target for treatment of type II diabetes and obesity. A previous report has shown that mammalian AMPK alpha1 catalytic subunit including autoinhibitory domain was inactive. To test the hypothesis that small molecules can activate AMPK through antagonizing the autoinhibition in alpha subunits, we screened a chemical library with inactive human alpha1(394) (alpha1, residues 1-394) and found a novel small-molecule activator, PT1, which dose-dependently activated AMPK alpha1(394), alpha1(335), alpha2(398), and even heterotrimer alpha1beta1gamma1. Based on PT1-docked AMPK alpha1 subunit structure model and different mutations, we found PT1 might interact with Glu-96 and Lys-156 residues near the autoinhibitory domain and directly relieve autoinhibition. Further studies using L6 myotubes showed that the phosphorylation of AMPK and its downstream substrate, acetyl-CoA carboxylase, were dose-dependently and time-dependently increased by PT1 with-out an increase in cellular AMP:ATP ratio. Moreover, in HeLa cells deficient in LKB1, PT1 enhanced AMPK phosphorylation, which can be inhibited by the calcium/calmodulin-dependent protein kinase kinases inhibitor STO-609 and AMPK inhibitor compound C. PT1 also lowered hepatic lipid content in a dose-dependent manner through AMPK activation in HepG2 cells, and this effect was diminished by compound C. Taken together, these data indicate that this small-molecule activator may directly activate AMPK via antagonizing the autoinhibition in vitro and in cells. This compound highlights the effort to discover novel AMPK activators and can be a useful tool for elucidating the mechanism responsible for conformational change and autoinhibitory regulation of AMPK.

Topics: Acetyl-CoA Carboxylase; Adenosine Monophosphate; Adenosine Triphosphate; AMP-Activated Protein Kinase Kinases; AMP-Activated Protein Kinases; Benzimidazoles; Diabetes Mellitus, Type 2; Energy Metabolism; Enzyme Activation; Enzyme Activators; HeLa Cells; Humans; Multienzyme Complexes; Myoblasts; Naphthalimides; Obesity; Phosphorylation; Protein Serine-Threonine Kinases; Protein Structure, Quaternary; Pyrazoles; Pyrimidines; Time Factors