Curcumin by activation of adenosine A2A receptor stimulates protein kinase a and potentiates inhibitory effect of cangrelor on platelets

The purpose of this work was to examine whether the level of cAMP accumulation and protein kinase A (PKA) activity influence atrial natriuretic factor (ANF)-dependent guanosine 3',5'-cyclic monophosphate (cGMP) production in two renal cell types: rabbit cortical vascular smooth muscle cells (RCSMC) and SV-40-transformed human glomerular visceral epithelial cells (HGVEC-SV1). N-[2-(p-bromocinnamylamino)ethyl]- 5-isoquinolinesulfonamide (H-89), a PKA inhibitor, decreased ANF-stimulated cGMP production in RCSMC in a time- and concentration-dependent manner. ANF-stimulated cGMP production was markedly inhibited after prolonged 9- and 18-h incubations with 25 microM H-89 (52 and 65%, respectively) but was not altered after exposure of cells to this agent for 1 h. 1-(5-Isoquinolinylsulfonyl)-2-methylpiperazine and N-(2-[methylamino]ethyl)-5-isoquinolinesulfonamide, protein kinase inhibitors not selective for PKA, did not reproduce the effect of H-89, even at higher concentrations (50 and 100 microM). Cycloheximide (10 microM), a protein synthesis inhibitor, limited the inhibitory effect of H-89, although alone it did not modify the ANF-stimulated cGMP production. H-89 did not affect cGMP production when it was stimulated by SIN-1, a nitric oxide donor. Prolonged incubation (18 h) with 8-bromo cAMP or cholera toxin, an activator of Gs protein resulting in adenylate cyclase stimulation, enhanced ANF-dependent cGMP production by 225 and 176%, respectively. This stimulatory effect was blocked by 25 microM H-89. 125I-ANF binding to RCSMC at 4 degrees C was not affected by preincubation of the cells with H-89. There was a 44% decrease in the expression of ANF C receptors measured as the ANF-(4-23)-displaceable 125I-ANF binding at 37 degrees C, which could not, however, explain the inhibitory effect of H-89 on cGMP production. Modulation of ANF- and C-type natriuretic peptide-dependent cGMP production by H-89 and cholera toxin was also found in HGVEC-SV1 with the same characteristics as in RCSMC. Taken together, these results suggest that PKA activity controls the function of natriuretic peptide guanylate cyclase-coupled receptors in the two cell types studied. PKA-dependent inhibition of a negatively regulatory protein distinct from the receptor itself seems necessary for a full cGMP response.

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Terbutaline, forskolin and cAMP reduce secretion of aqueous humour in the isolated bovine eye

PLoS ONE ◽

10.1371/journal.pone.0244253 ◽

2020 ◽

Vol 15 (12) ◽

pp. e0244253

Author(s):

Mohammad Shahidullah ◽

William Stuart Wilson ◽

Kazi Rafiq ◽

Mahmudul Hasan Sikder ◽

Jannatul Ferdous ◽

...

Keyword(s):

Protein Kinase ◽

Cyclic Amp ◽

Protein Kinase A ◽

Aqueous Humour ◽

Calcium Release ◽

Drug Effects ◽

Inhibitory Effect ◽

Plateau Phase ◽

Intracellular Ca ◽

Kinase A

In order to elucidate involvement of cyclic AMP and intracellular Ca2+,[Ca2+]i, in the modulation of aqueous humour formation (AHF), we studied the effects of terbutaline, forskolin and 8-Br-cAMP in the isolated bovine eye. We also studied the interaction of cAMP on calcium signaling in cultured ciliary epithelial (CE) cells. Drug effects on AHF were measured by fluorescein dilution. Drug effects on [Ca2+]i were studied by the fura-2 fluorescence ratio technique. Terbutaline (100 nmol-100 M), forskolin (30 nM-100 M) or 8-Br-cAMP (100 nM– 10 μM), administered in the arterial perfusate produced significant reductions in AHF. The AH reducing effect of terbutaline was blocked by a selective inhibitor of protein kinase A (KT-5720). ATP (100 M) caused a rapid, transient (peak) increase in [Ca2+]i followed by a sustained plateau phase lasting more than 5 minutes. Preincubation of the cells (6 min) with terbutaline, forskolin or 8-Br-cAMP significantly reduced the peak calcium response to ATP. The sustained plateau phase of the response, on the other hand, was augmented by each of the agents. KT-5720 partially reversed the inhibitory effect of terbutaline on the peak and totally inhibited its effect on the plateau phase. These data indicate: (a) that AHF in the bovine eye can be manipulated through cyclic AMP, operating via protein kinase A, (b) that protein kinase A can affect [Ca2+]i homeostasis, (c) that calcium release from the intracellular store, not the entry, affects AHF, and (d) that interaction of [Ca2+]i with cAMP plays a role in modulating AH secretion.

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Adenosine pretreatment attenuates angiotensin II-mediated p38 MAPK activation in a protein kinase A dependent manner

Asian Biomedicine ◽

10.2478/abm-2010-0094 ◽

2010 ◽

Vol 4 (5) ◽

pp. 721-729

Author(s):

Hamid Yaghooti ◽

Mohsen Firoozrai ◽

Soudabeh Fallah ◽

Mohammad Reza Khorramizadeh

Keyword(s):

Angiotensin Ii ◽

Protein Kinase ◽

Protein Kinase A ◽

P38 Mapk ◽

Inflammatory Mediators ◽

Endothelial Permeability ◽

Renin Angiotensin System ◽

Inhibitory Effect ◽

Dependent Manner ◽

Kinase A

Abstract Background: Adenosine is known as a protective and anti-inflammatory nucleoside. Angiotensin II is the main hormone of the renin-angiotensin system. It is associated with endothelial permeability, recruitment, and activation of the immune cells through induction of inflammatory mediators. Matrix metalloproteinase-9 (MMP-9) plays an important role in inflammatory processes mediated by macrophages. Objectives: Investigate whether adenosine pretreatment modulates angiotensin II-induced MMP-9 expression and activation of signaling molecules. Methods: Human monocytic U-937 cells were treated with either adenosine or angiotensin II alone or angiotensin II following a pretreatment with adenosine. Supernatants were analyzed for MMP-9 activity by zymography method. MMP-9 gene expression was analyzed using real-time PCR. Activation of inflammatory mediators IκB-α, NF-κB, JNK, p38 MAPK, and STAT3 were analyzed by a multi-target ELISA kit. Association of Protein kinase A (PKA) in adenosine effects was studied by pre-incubation with H89, a selective PKA inhibitor. Results: Treatment of the cells with angiotensin II significantly increased MMP-9 production (p <0.05). Adenosine pretreatment did not attenuate this angiotensin II effect. Angiotensin II treatment induced NF-κB, JNK and p38 activation. Pretreatment with adenosine prior to angiotensin II stimulation showed a 40% inhibitory effect on p38 induction (p <0.05). This effect was reversed by PKA inhibition. Conclusion: The present data confirmed that monocytic MMP-9 was a target gene for angiotensin II. Adenosine pretreatment did not inhibit MMP-9 increase in response to angiotensin II. However, it showed a potential inhibitory effect on angiotensin II inflammatory signaling.

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Adenosine-A2a Receptor Down-Regulates Cerebral Smooth Muscle L-Type Ca2+ Channel Activity via Protein Tyrosine Phosphatase, Not cAMP-Dependent Protein Kinase

Molecular Pharmacology ◽

10.1124/mol.64.3.640 ◽

2003 ◽

Vol 64 (3) ◽

pp. 640-649 ◽

Cited By ~ 26

Author(s):

Katrina Murphy ◽

Volodymyr Gerzanich ◽

Hui Zhou ◽

Svetlana Ivanova ◽

Yafeng Dong ◽

...

Keyword(s):

Smooth Muscle ◽

Protein Kinase ◽

Protein Tyrosine Phosphatase ◽

Tyrosine Phosphatase ◽

Adenosine A2a Receptor ◽

Channel Activity ◽

Dependent Protein Kinase ◽

A2a Receptor ◽

Dependent Protein ◽

Adenosine A2a

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The cross-regulation of Gi-protein by cholera toxin involves a phosphorylation by protein kinase A

Biochemical Journal ◽

10.1042/bj3060765 ◽

1995 ◽

Vol 306 (3) ◽

pp. 765-769 ◽

Cited By ~ 6

Author(s):

R Levistre ◽

M Berguerand ◽

G Bereziat ◽

J Masliah

Keyword(s):

Arachidonic Acid ◽

Protein Kinase ◽

Protein Kinase A ◽

Cholera Toxin ◽

Inhibitory Effect ◽

Negative Control ◽

Adp Ribosylation ◽

Gi Proteins ◽

Kinase A

Pretreatment of alveolar macrophages with cholera toxin inhibits the release of arachidonic acid induced by the chemotactic peptide N-formylmethionyl-leucyl-phenylalanine. The results presented here show that cholera toxin might exert its inhibitory effect through the phosphorylation of Gi alpha by protein kinase A (PKA). (1) Gi-proteins from cells pretreated with cholera toxin showed parallel increases in their sensitivity to ADP-ribosylation by toxins in vitro and in Gi alpha phosphorylation. By contrast, the Gi alpha concentration was unchanged. (2) Cholera toxin pretreatment also decreased the functional activity of Gi, as assessed by the inhibition (80%) of agonist-induced binding of guanosine-5′-[gamma-thio]triphosphate (GTP[gamma S]). (3) These effects of cholera toxin were blocked by a specific PKA inhibitor, N-(2-[methyl-amino]ethyl)-3-isoquinolinesulphonamide dihydrochloride (H8) and mimicked by a cyclic AMP (cAMP) analogue and a phosphatase inhibitor. (4) Gi alpha was also phosphorylated in vitro by the catalytic subunit of PKA. In contrast with other cell systems, the stimulation of protein kinase C seems to have no effect on the sensitivity of Gi to ADP-ribosylation or on its phosphorylation. Therefore, the phosphorylation of Gi-proteins by PKA seems to be the actual target of the negative control of arachidonic acid release via the cAMP-mediated pathway.

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Adenosine A2a receptor stimulation prevents hepatocyte lipotoxicity and non-alcoholic steatohepatitis (NASH) in rats

Clinical Science ◽

10.1042/cs20110504 ◽

2012 ◽

Vol 123 (5) ◽

pp. 323-332 ◽

Cited By ~ 23

Author(s):

Chiara Imarisio ◽

Elisa Alchera ◽

Salvatore Sutti ◽

Guido Valente ◽

Francesca Boccafoschi ◽

...

Keyword(s):

Protein Kinase ◽

Critical Role ◽

Intraperitoneal Administration ◽

Adenosine A2a Receptor ◽

Mitogen Activated Protein Kinase ◽

Receptor Stimulation ◽

Deficient Diet ◽

Alcoholic Steatohepatitis ◽

A2a Receptor ◽

Adenosine A2a

NEFA (non-esterified ‘free’ fatty acid)-mediated lipotoxicity plays a critical role in the pathogenesis of NASH (non-alcoholic steatohepatitis). In the light of the growing need for new therapeutic options for NASH, we investigated the action of A2aR (adenosine A2a receptor) stimulation against lipotoxicity. The effects of the A2aR agonist CGS21680 [2-p-(2-carboxyethyl)phenethylamino-5′-N-ethylcarboxyamidoadenosine] were evaluated ‘in vitro’ in liver cells exposed to SA (stearic acid) and ‘in vivo’ in rats with NASH induced by 8 weeks of feeding with an MCD diet (methionine/choline-deficient diet). In cultured hepatocytes, SA promoted apoptosis by inducing MKK4 (mitogen-activated protein kinase kinase 4)/SEK1 (stress-activated protein kinase/extracellular-signal-regulated kinase kinase-1) and JNK-1/2 (c-Jun N-terminal kinase-1/2) activation. CGS21680 addition prevented JNK-1/2 activation and reduced apoptosis without interfering with lipid accumulation. CGS21680 action required PI3K (phosphoinositide 3-kinase)/Akt-mediated block of MKK4/SEK1. Consistently, PI3K inhibition with wortmannin abolished the cytoprotective action of CGS21680 and reverted MKK4 inhibition. SA lipotoxicity was also prevented by transfecting HTC cells with a specific MKK4/SEK1 siRNA (small interfering RNA). In rats receiving the MCD diet, the development of NASH was associated with MKK4/SEK1 and JNK-1/2 activation. CGS21680 (0.5 mg/kg of body weight, intraperitoneal) administration to MCD-fed rats prevented JNK-1/2 activation by acting on MKK4/SEK1. CGS21680 also effectively reduced NASH-associated ALT (alanine aminotransferase) release, hepatocyte apoptosis, liver inflammation and fibrosis without affecting hepatic steatosis. Taken together, these results demonstrate that, by inhibiting JNK-1/2, A2aR stimulation reduces lipotoxicity and ameliorates NASH, giving a rationale to investigate A2aR agonists as possible new therapeutic agents in preventing fatty liver progression to NASH.

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