scholarly journals Stimulation of Wnt/β-Catenin Signaling to Improve Bone Development by Naringin via Interacting with AMPK and Akt

2015 ◽  
Vol 36 (4) ◽  
pp. 1563-1576 ◽  
Author(s):  
Dawei Wang ◽  
Wenpu Ma ◽  
Fu Wang ◽  
Jinlei Dong ◽  
Dan Wang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Bone Development ◽  
Akt Inhibitor ◽  
Ampk Signaling ◽  
T Cell Factor ◽  
Protein Expressions ◽  
Amp Activated Protein Kinase ◽  
Umr 106

Background/Aims: Naringin is a naturally existing compound in citrus fruits and has been elucidated to promote bone development and maintenance. Methods: The biological roles of naringin were investigated in vitro using osteoblast-like UMR-106 cells, and in vivo through performing ovariectomy to mimic osteoporosis in female mice. Since Wnt/β-catenin signaling is involved in osteoblastogenesis, the effect of naringin on Wnt/β-catenin signaling was studied. Results: Naringin promoted the mRNA and protein expressions of β-catenin, and improved Ser552 phosphorylation on β-catenin in UMR-106 cells, which leads to the activation of lymphoid enhancer factor (LEF)/ T-cell factor (TCF) transcription factors. The recruitments of protein kinase B (Akt) inhibitor (Akti-1/2) and AMP-activated protein kinase (AMPK) inhibitor (Dorsomorphin) reduced the influence of naringin on β-catenin phosphorylation, suggesting naringin activates β-catenin via regulating Akt and AMPK. In ovariectomized (OVX) mice naringin treatment improved the bone strength while AMPK and Akt inhibitors partly reversed the effect, which further proved the involvements of Akt and AMPK in the action of naringin in vivo. Conclusion: Our study points to a novel finding on the mechanism of naringin in facilitating bone formation via Akt and AMPK signaling.

Hypoxia and AMP independently regulate AMP-activated protein kinase activity in heart

2005 ◽  
Vol 288 (5) ◽  
pp. H2412-H2421 ◽  
Author(s):  
Markus Frederich ◽  
Li Zhang ◽  
James A. Balschi
Keyword(s):  
Protein Kinase ◽  
Metabolic Inhibitors ◽  
Protein Kinase Activity ◽  
Α Subunit ◽  
Rat Hearts ◽  
Upstream Kinase ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

The hypothesis was tested that hypoxia increases AMP-activated protein kinase (AMPK) activity independently of AMP concentration ([AMP]) in heart. In isolated perfused rat hearts, cytosolic [AMP] was changed from 0.2 to 16 μM using metabolic inhibitors during both normal oxygenation (95% O2-5% CO2, normoxia) and limited oxygenation (95% N2-5% CO2, hypoxia). Total AMPK activity measured in vitro ranged from 2 to 40 pmol·min−1·mg protein−1 in normoxic hearts and from 5 to 55 pmol·min−1·mg protein−1 in hypoxic hearts. The dependence of the in vitro total AMPK activity on the in vivo cytosolic [AMP] was determined by fitting the measurements from individual hearts to a hyperbolic equation. The [AMP] resulting in half-maximal total AMPK activity ( A0.5) was 3 ± 1 μM for hypoxic hearts and 28 ± 13 μM for normoxic hearts. The A0.5 for α2-isoform AMPK activity was 2 ± 1 μM for hypoxic hearts and 13 ± 8 μM for normoxic hearts. Total AMPK activity correlated with the phosphorylation of the Thr172 residue of the AMPK α-subunit. In potassium-arrested hearts perfused with variable O2 content, α-subunit Thr172 phosphorylation increased at O2 ≤ 21% even though [AMP] was <0.3 μM. Thus hypoxia or O2 ≤ 21% increased AMPK phosphorylation and activity independently of cytosolic [AMP]. The hypoxic increase in AMPK activity may result from either direct phosphorylation of Thr172 by an upstream kinase or reduction in the A0.5 for [AMP].

5′-AMP-activated protein kinase is inactivated by adrenergic signalling in adult cardiac myocytes

2011 ◽  
Vol 32 (2) ◽  
pp. 197-209 ◽  
Author(s):  
Yugo Tsuchiya ◽  
Fiona C. Denison ◽  
Richard B. Heath ◽  
David Carling ◽  
David Saggerson
Keyword(s):  
Protein Kinase ◽  
Cardiac Myocytes ◽  
Calcium Signalling ◽  
Metabolic Stress ◽  
Protein Kinase Activity ◽  
Adult Rat ◽  
Protein Kinase C Inhibitor ◽  
Amp Activated Protein Kinase

In adult rat cardiac myocytes adrenaline decreased AMPK (AMP-activated protein kinase) activity with a half-time of approximately 4 min, decreased phosphorylation of AMPK (α-Thr172) and decreased phosphorylation of ACC (acetyl-CoA carboxylase). Inactivation of AMPK by adrenaline was through both α1- and β-ARs (adrenergic receptors), but did not involve cAMP or calcium signalling, was not blocked by the PKC (protein kinase C) inhibitor BIM I (bisindoylmaleimide I), by the ERK (extracellular-signal-regulated kinase) cascade inhibitor U0126 or by PTX (pertussis toxin). Adrenaline caused no measurable change in LKB1 activity. Adrenaline decreased AMPK activity through a process that was distinct from AMPK inactivation in response to insulin or PMA. Neither adrenaline nor PMA altered the myocyte AMP:ATP ratio although the adrenaline effect was attenuated by oligomycin and by AICAR (5-amino-4-imidazolecarboxamide-1-β-D-ribofuranoside), agents that mimic ‘metabolic stress’. Inactivation of AMPK by adrenaline was abolished by 1 μM okadaic acid suggesting that activation of PP2A (phosphoprotein phosphatase 2A) might mediate the adrenaline effect. However, no change in PP2A activity was detected in myocyte extracts. Adrenaline increased phosphorylation of the AMPK β-subunit in vitro but there was no detectable change in vivo in phosphorylation of previously identified AMPK sites (β-Ser24, β-Ser108 or β-Ser182) suggesting that another site(s) is targeted.

scholarly journals Statins Activate AMP-Activated Protein Kinase In Vitro and In Vivo

Circulation ◽  
2006 ◽  
Vol 114 (24) ◽  
pp. 2655-2662 ◽  
Author(s):  
Wei Sun ◽  
Tzong-Shyuan Lee ◽  
Minjia Zhu ◽  
Chunang Gu ◽  
Yinsheng Wang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Amp Activated Protein Kinase

Adiponectin promotes VEGF-C-dependent lymphangiogenesis by inhibiting miR-27b through a CaMKII/AMPK/p38 signaling pathway in human chondrosarcoma cells

2016 ◽  
Vol 130 (17) ◽  
pp. 1523-1533 ◽  
Author(s):  
Chun-Yin Huang ◽  
An-Chen Chang ◽  
Hsien-Te Chen ◽  
Shih-Wei Wang ◽  
Yuan-Shun Lo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathway ◽  
Tube Formation ◽  
Human Chondrosarcoma ◽  
Dependent Protein ◽  
And Migration ◽  
Factor C ◽  
Amp Activated Protein Kinase

Chondrosarcoma is the second most frequently occurring type of bone malignancy characterized by distant metastatic propensity. Vascular endothelial growth factor-C (VEGF-C) is the major lymphangiogenic factor, and makes crucial contributions to tumour lymphangiogenesis and lymphatic metastasis. Adiponectin is a protein hormone secreted predominantly by differentiated adipocytes. In recent years, adiponectin has also been indicated as facilitating tumorigenesis, angiogenesis and metastasis. However, the effect of adiponectin on VEGF-C regulation and lymphangiogenesis in chondrosarcoma has remained largely a mystery. In the present study, we have shown a clinical correlation between adiponectin and VEGF-C, as well as tumour stage, in human chondrosarcoma tissues. We further demonstrated that adiponectin promoted VEGF-C expression and secretion in human chondrosarcoma cells. The conditioned medium from adiponectin-treated cells significantly induced tube formation and migration of human lymphatic endothelial cells. In addition, adiponectin knock down inhibited lymphangiogenesis in vitro and in vivo. We also found that adiponectin-induced VEGF-C is mediated by the calmodulin-dependent protein kinase II (CaMKII), AMP-activated protein kinase (AMPK) and p38 signaling pathway. Furthermore, the expression of miR-27b was negatively regulated by adiponectin via the CaMKII, AMPK and p38 cascade. The present study is the first to describe the mechanism of adiponectin-promoted lymphangiogenesis by up-regulating VEGF-C expression in chondrosarcomas. Thus, adiponectin could serve as a therapeutic target in chondrosarcoma metastasis and lymphangiogenesis.

AMP-activated protein kinase (AMPK) regulates in vitro bone formation and bone mass in vivo

Bone ◽  
2010 ◽  
Vol 47 ◽  
pp. S44
Author(s):  
M. Shah⁎ ◽  
A. Bataveljic ◽  
T.R. Arnett ◽  
B. Viollet ◽  
L.K. Saxon ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Bone Formation ◽  
Bone Mass ◽  
Amp Activated Protein Kinase

scholarly journals AMP-activated protein kinase pathway and bone metabolism

2011 ◽  
Vol 212 (3) ◽  
pp. 277-290 ◽  
Author(s):  
J Jeyabalan ◽  
M Shah ◽  
B Viollet ◽  
C Chenu
Keyword(s):  
Protein Kinase ◽  
Energy Homeostasis ◽  
Bone Cells ◽  
Peripheral Tissues ◽  
Ampk Signaling ◽  
Obesity And Diabetes ◽  
Regulate Food Intake ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

There is increasing evidence that osteoporosis, similarly to obesity and diabetes, could be another disorder of energy metabolism. AMP-activated protein kinase (AMPK) has emerged over the last decade as a key sensing mechanism in the regulation of cellular energy homeostasis and is an essential mediator of the central and peripheral effects of many hormones on the metabolism of appetite, fat and glucose. Novel work demonstrates that the AMPK signaling pathway also plays a role in bone physiology. Activation of AMPK promotes bone formationin vitroand the deletion of α or β subunit of AMPK decreases bone mass in mice. Furthermore, AMPK activity in bone cells is regulated by the same hormones that regulate food intake and energy expenditure through AMPK activation in the brain and peripheral tissues. AMPK is also activated by antidiabetic drugs such as metformin and thiazolidinediones (TZDs), which also impact on skeletal metabolism. Interestingly, TZDs have detrimental skeletal side effects, causing bone loss and increasing the risk of fractures, although the role of AMPK mediation is still unclear. These data are presented in this review that also discusses the potential roles of AMPK in bone as well as the possibility for AMPK to be a future therapeutic target for intervention in osteoporosis.

scholarly journals Dissecting the Role of 5′-AMP for Allosteric Stimulation, Activation, and Deactivation of AMP-activated Protein Kinase

2006 ◽  
Vol 281 (43) ◽  
pp. 32207-32216 ◽  
Author(s):  
Marianne Suter ◽  
Uwe Riek ◽  
Roland Tuerk ◽  
Uwe Schlattner ◽  
Theo Wallimann ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Phosphatase ◽  
Energy Homeostasis ◽  
Adenine Nucleotides ◽  
Enzyme Preparations ◽  
Activity Measurements ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) is a heterotrimeric protein kinase that is crucial for cellular energy homeostasis of eukaryotic cells and organisms. Here we report on the activation of AMPK α1β1γ1 and α2β2γ1 by their upstream kinases (Ca2+/calmodulin-dependent protein kinase kinase-β and LKB1-MO25α-STRADα), the deactivation by protein phosphatase 2Cα, and on the extent of stimulation of AMPK by its allosteric activator AMP, using purified recombinant enzyme preparations. An accurate high pressure liquid chromatography-based method for AMPK activity measurements was established, which allowed for direct quantitation of the unphosphorylated and phosphorylated artificial peptide substrate, as well as the adenine nucleotides. Our results show a 1000-fold activation of AMPK by the combined effects of upstream kinase and saturating concentrations of AMP. The two AMPK isoforms exhibit similar specific activities (6 μmol/min/mg) and do not differ significantly by their responsiveness to AMP. Due to the inherent instability of ATP and ADP, it proved impossible to assay AMPK activity in the absolute absence of AMP. However, the half-maximal stimulatory effect of AMP is reached below 2 μm. AMP does not appear to augment phosphorylation by upstream kinases in the purified in vitro system, but deactivation by dephosphorylation of AMPK α-subunits at Thr-172 by protein phosphatase 2Cα is attenuated by AMP. Furthermore, it is shown that neither purified NAD+ nor NADH alters the activity of AMPK in a concentration range of 0–300 μm, respectively. Finally, evidence is provided that ZMP, a compound formed in 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside-treated cells to activate AMPK in vivo, allosterically activates purified AMPK in vitro, but compared with AMP, maximal activity is not reached. These data shed new light on physiologically important aspects of AMPK regulation.

scholarly journals Effects of AMP-Activated Protein Kinase in Cerebral Ischemia

2009 ◽  
Vol 30 (3) ◽  
pp. 480-492 ◽  
Author(s):  
Jun Li ◽  
Louise D McCullough
Keyword(s):  
Protein Kinase ◽  
In Vivo Studies ◽  
Ampk Activation ◽  
Vigorous Exercise ◽  
Nitric Oxide Signaling ◽  
Reductase Inhibitors ◽  
Amp Activated Protein Kinase ◽  
The Brain

AMP-activated protein kinase (AMPK) is a serine threonine kinase that is highly conserved through evolution. AMPK is found in most mammalian tissues including the brain. As a key metabolic and stress sensor/effector, AMPK is activated under conditions of nutrient deprivation, vigorous exercise, or heat shock. However, it is becoming increasingly recognized that changes in AMPK activation not only signal unmet metabolic needs, but also are involved in sensing and responding to ‘cell stress’, including ischemia. The downstream effect of AMPK activation is dependent on many factors, including the severity of the stressor as well as the tissue examined. This review discusses recent in vitro and in vivo studies performed in the brain/neuronal cells and vasculature that have contributed to our understanding of AMPK in stroke. Recent data on the potential role of AMPK in angiogenesis and neurogenesis and the interaction of AMPK with 3-hydroxy-3-methy-glutaryl-CoA reductase inhibitors (statins) agents are highlighted. The interaction between AMPK and nitric oxide signaling is also discussed.

scholarly journals Targeting redox regulatory site of protein kinase B impedes neutrophilic inflammation in lung injury

2018 ◽  
Author(s):  
Po-Jen Chen ◽  
I-Ling Ko ◽  
Chia-Lin Lee ◽  
Hao-Chun Hu ◽  
Fang-Rong Chang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Lung Injury ◽  
Inflammatory Responses ◽  
Protein Kinase B ◽  
Reduced Form ◽  
Human Neutrophils ◽  
Akt Inhibitor ◽  
Neutrophilic Inflammation

AbstractNeutrophil activation has a pathogenic effect in inflammatory diseases. Protein kinase B (PKB)/AKT regulates diverse cellular responses. However, the significance of AKT in neutrophilic inflammation is still not well understood. Here, we identified CLLV-1 as a novel AKT inhibitor. CLLV-1 inhibited respiratory burst, degranulation, chemotaxis, and AKT phosphorylation in activated human neutrophils and dHL-60 cells. Significantly, CLLV-1 blocked AKT activity and covalently reacted with AKT Cys310 in vitro. The AKT309-313 peptide-CLLV-1 adducts were determined by NMR or mass spectrometry assay. The alkylation agent-conjugated AKT (reduced form) level was also inhibited by CLLV-1. Additionally, CLLV-1 ameliorated lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. CLLV-1 acts as a covalent allosteric AKT inhibitor by targeting AKT Cys310 to restrain inflammatory responses in human neutrophils and LPS-induced ALI in vivo. Our findings provide a mechanistic framework for redox modification of AKT that may serve as a novel pharmacological target to alleviate neutrophilic inflammation.

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