dorsomorphin and acadesine

The 5'-AMP-activated protein kinase (AMPK) functions as a cellular energy sensor. 5-Aminoimidazole-4-carboxyamide-1-β-D-ribofranoside (AICAR) is a chemical activator of AMPK. In the liver, AICAR suppresses expression of thephosphoenolpyruvate carboxykinase(PEPCK) gene. The rat enhancer of split- and hairy-related protein-2 (SHARP-2) is an insulin-inducible transcriptional repressor and its target is thePEPCKgene. In this study, we examined an issue of whether theSHARP-2gene expression is regulated by AICAR via the AMPK. AICAR increased the level of SHARP-2 mRNA in H4IIE cells. Whereas an AMPK inhibitor, compound-C, had no effects on the AICAR-induction, inhibitors for both phosphoinositide 3-kinase (PI 3-K) and protein kinase C (PKC) completely diminished the effects of AICAR. Western blot analyses showed that AICAR rapidly activated atypical PKC lambda (aPKCλ). In addition, when a dominant negative form of aPKCλ was expressed, the induction of SHARP-2 mRNA level by AICAR was inhibited. Calcium ion is not required for the activation of aPKCλ. A calcium ion-chelating reagent had no effects on the AICAR-induction. Furthermore, the AICAR-induction was inhibited by treatment with an RNA polymerase inhibitor or a protein synthesis inhibitor. Thus, we conclude that the AICAR-induction of theSHARP-2gene is mediated at transcription level by a PI 3-K/aPKCλ pathway.

Topics: Aminoimidazole Carboxamide; AMP-Activated Protein Kinases; Animals; Basic Helix-Loop-Helix Transcription Factors; Calcium; Cycloheximide; Dactinomycin; Enzyme Activation; Gene Expression; HEK293 Cells; Homeodomain Proteins; Humans; Intracellular Signaling Peptides and Proteins; Isoenzymes; Liver; Phosphatidylinositol 3-Kinases; Phosphoenolpyruvate Carboxykinase (GTP); Phosphoinositide-3 Kinase Inhibitors; Protein Kinase C; Protein Synthesis Inhibitors; Pyrazoles; Pyrimidines; Rats; Ribonucleosides; RNA Polymerase II; RNA, Messenger; Signal Transduction; Transcription, Genetic

As a master metabolic sensor, AMP-activated protein kinase (AMPK) is involved in different fundamental cellular processes. Regulation of AMPK activity either by agonists (e.g., AICAR) or by antagonists (e.g., Compound C) has been widely employed to study the physiological functions of AMPK. However, mounting evidence indicates AMPK-independent effects for these chemicals and how they regulate immune cell functions remains largely unknown. Herein, using T cells from AMPK conditional knockout mice and their wild type littermates, we demonstrate that AICAR and Compound C can, indeed, activate or inhibit AMPK activity in T cells, respectively. Specifically, AICAR inhibits, but Compound C promotes, Ca2+-induced T cell death in an AMPK-dependent manner. In contrast, our data also demonstrate that AICAR and Compound C inhibit T cell activation and cytokine production in an AMPK-independent manner. Moreover, we find that the AMPK-independent activity of AICAR and Compound Cis mediated via the mTOR signaling pathway in activated T cells. Our results not only reveal the critical role of AMPK in regulating T cell survival and function, but also demonstrate AMPK-dependent and independent rolesof AICAR/Compound C in regulating T cell responses, thus suggesting a context-dependent effect of these "AMPK regulators".

Topics: Aminoimidazole Carboxamide; AMP-Activated Protein Kinases; Animals; Calcium Signaling; Cell Death; Cells, Cultured; Cytokines; Dose-Response Relationship, Drug; Enzyme Activation; Enzyme Activators; Genotype; Immunologic Factors; Lymphocyte Activation; Mice, Knockout; Phenotype; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines; Ribonucleosides; T-Lymphocytes; TOR Serine-Threonine Kinases

The epithelial-mesenchymal transition (EMT) is a novel mechanism that promotes renal fibrosis. Transforming growth factor-β (TGF-β), angiotensin II, aldosterone, high glucose, and urinary albumin are well-known causes of EMT and renal fibrosis. We examined whether and how activation of AMP-activated protein kinase (AMPK) suppressed EMT induced by the above agents in tubular epithelial cells. All experiments were performed using HK-2 cells. Protein expression was measured by Western blot analysis. Intracellular reactive oxygen species (ROS) were analyzed by flow cytometry. Exposure of tubular cells to TGF-β (10 ng/ml), angiotensin II (1 μM), aldosterone (100 nM), high glucose (30 mM), and albumin (5 mg/ml) for 5 days induced EMT, as shown by upregulation of α-smooth muscle actin and downregulation of E-cadherin. ROS and NADPH oxidase 4 (Nox4) expression were increased, and antioxidants such as tiron and N-acetylcysteine inhibited EMT induction. Metformin (the best known clinical activator of AMPK) suppressed EMT induction through inhibition of ROS via induction of heme oxygenase-1 and endogenous antioxidant thioredoxin. An AMPK inhibitor (compound C) and AMPK small interfering RNA blocked the effect of metformin, and another AMPK activator [5-aminoimidazole-4-carboxamide-1β riboside (AICAR)] exerted the same effects as metformin. In conclusion, AMPK activation might be beneficial in attenuating the tubulointerstitial fibrosis induced by TGF-β, angiotensin II, aldosterone, high glucose, and urinary albumin.

Topics: Albumins; Aldosterone; Aminoimidazole Carboxamide; AMP-Activated Protein Kinases; Angiotensin II; Cell Line; Epithelial-Mesenchymal Transition; Glucose; Heme Oxygenase-1; Humans; Metformin; NADPH Oxidase 4; NADPH Oxidases; Nephrosclerosis; Pyrazoles; Pyrimidines; Reactive Oxygen Species; Ribonucleosides; Thioredoxins; Transforming Growth Factor beta

Acadesine, an adenosine-regulating agent and activator of AMP-activated protein kinase, has been shown to possess antiinflammatory activity. This study investigated whether and how acadesine inhibits tissue factor (TF) expression and thrombus formation.. Human umbilical vein endothelial cells and human peripheral blood monocytes were stimulated with lipopolysaccharide to induce TF expression. Pretreatment with acadesine dramatically suppressed the clotting activity and expression of TF (protein and mRNA). These inhibitory effects of acadesine were unchanged for endothelial cells treated with ZM241385 (a specific adenosine A(2A) receptor antagonist) or AMP-activated protein kinase inhibitor compound C, and in macrophages lacking adenosine A(2A) receptor or alpha1-AMP-activated protein kinase. In endothelial cells and macrophages, acadesine activated the phosphoinositide 3-kinase/Akt signaling pathway, reduced the activity of mitogen-activated protein kinases, and consequently suppressed TF expression by inhibiting the activator protein-1 and NF-kappaB pathways. In mice, acadesine suppressed lipopolysaccharide-mediated increases in blood coagulation, decreased TF expression in atherosclerotic lesions, and reduced deep vein thrombus formation.. Acadesine inhibits TF expression and thrombus formation by activating the phosphoinositide 3-kinase/Akt pathway. This novel finding implicates acadesine as a potentially useful treatment for many disorders associated with thrombotic pathology, such as angina pain, deep vein thrombosis, and sepsis.

Topics: Adenosine A2 Receptor Antagonists; Aminoimidazole Carboxamide; AMP-Activated Protein Kinases; Animals; Apolipoproteins E; Atherosclerosis; Blood Coagulation; Cells, Cultured; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelial Cells; Enzyme Activation; Fibrinolytic Agents; Humans; Lipopolysaccharides; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Monocytes; NF-kappa B; Phosphatidylinositol 3-Kinases; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Pyrazoles; Pyrimidines; Receptor, Adenosine A2A; Ribonucleosides; RNA, Messenger; Sepsis; Signal Transduction; Thromboplastin; Transcription Factor AP-1; Triazines; Triazoles; Up-Regulation; Venous Thrombosis

Macrophages (MPhis) utilize macropinocytosis to integrate immune and metabolic signals in order to initiate an effective immune response. Diabetes is characterized by metabolic abnormalities and altered immune function. Here we examine the influence of diabetes on macropinocytosis in primary mouse macrophages and in an in vitro diabetes model.. The data demonstrate that peritoneal MPhis from diabetic (db/db) mice had reduced macropinocytosis when compared to MPhis from non-diabetic (db/+) mice. Additionally, MPhis cultured in hyperglycemic conditions were less adept at macropinocytosis than those cultured in low glucose. Notably, AMP-activated protein kinase (AMPK) activity was decreased in MPhis cultured in hyperglycemic conditions. Activation of AMPK with leptin or 5-aminoimidazole-4-carboxamide-1-beta-riboside (AICAR) increased macropinocytosis and inhibition of AMPK with compound C decreased macropinocytosis.. Taken together, these findings indicate that MPhis from diabetic mice have decreased macropinocytosis. This decrease appears dependent on reduced AMPK activity. These results demonstrate a previously unrealized role for AMPK in MPhis and suggest that increasing AMPK activity in diabetic MPhis could improve innate immunity and decrease susceptibility to infection.

Topics: Aminoimidazole Carboxamide; AMP-Activated Protein Kinases; Animals; Cell Culture Techniques; Cell Line, Tumor; Diabetes Mellitus, Type 2; Disease Models, Animal; Energy Metabolism; Glucose; Hyperglycemia; Immunity; Leptin; Macrophage Activation; Macrophages, Peritoneal; Mice; Pinocytosis; Pyrazoles; Pyrimidines; Ribonucleosides