2-Arachidonoylglycerol as an Endogenous Cue Negatively Regulates Attachment of the Mussel Perna viridis

Endocannabinoids play important roles in the functioning of various physiological systems in humans and non-mammalian animals, including invertebrates. However, information concerning their roles in physiological functions in members of the phylum Mollusca is scarce. Here the hypothesis that the endocannabinoids are involved in mediating settlement of marine invertebrates was tested. Two endocannabinoids [N-arachidonoyl ethanolamide (AEA) and 2-arachidonoyl glycerol (2-AG)], and two endocannabinoid-like lipids [N-Oleoylethanolamide (OEA) and N-Palmitoylethanolamide (PEA)] were detected in the green mussel Perna viridis. In particular, 2-AG was present at significantly higher levels in unattached P. viridis compared with attached mussels. The in vivo level of 2-AG was inversely correlated with the attachment activity of P. viridis. Furthermore, exposure to synthetic 2-AG inhibited attachment of P. viridis in a reversible manner. Transcriptomic analysis suggested that up-regulation of 2-AG synthase (Phospholipase C-β, PLC-β) and down-regulation of its degrading enzyme (Monoacylglycerol lipase, MAGL) resulted in higher levels of 2-AG in unattached mussels. A putative mechanism for the negative regulation of mussel attachment by 2-AG is proposed that involves a Ca2+- Nitric oxide (NO)- cyclic guanosine monophosphate (cGMP) pathway. This study broadens our understanding of the evolution and roles of the endocannabinoid system in animals, and reveals an endogenous regulatory cue for mussel attachment.

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Antinociceptive Activity of Methanol Extract ofMuntingia calaburaLeaves and the Mechanisms of Action Involved

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2012/890361 ◽

2012 ◽

Vol 2012 ◽

pp. 1-10 ◽

Cited By ~ 18

Author(s):

M. H. Mohd. Sani ◽

Z. A. Zakaria ◽

T. Balan ◽

L. K. Teh ◽

M. Z. Salleh

Keyword(s):

Methanol Extract ◽

Methyl Esters ◽

Cyclic Guanosine Monophosphate ◽

Guanosine Monophosphate ◽

Antinociceptive Activity ◽

Opioid Antagonist ◽

Hot Plate Test ◽

No Donor ◽

Cgmp Pathway

Muntingia calaburaL. (family Elaeocarpaceae) has been traditionally used to relieve various pain-related ailments. The present study aimed to determine the antinociceptive activity of methanol extract ofM. calaburaleaves (MEMC) and to elucidate the possible mechanism of antinociception involved. Thein vivochemicals (acetic acid-induced abdominal constriction and formalin-, capsaicin-, glutamate-, serotonin-induced paw licking test) and thermal (hot plate test) models of nociception were used to evaluate the extract antinociceptive activity. The extract (100, 250, and 500 mg/kg) was administered orally 60 min prior to subjection to the respective test. The results obtained demonstrated that MEMC produced significant (P<0.05) antinociceptive response in all the chemical- and thermal-induced nociception models, which was reversed after pretreatment with 5 mg/kg naloxone, a non-selective opioid antagonist. Furthermore, pretreatment with L-arginine (a nitric oxide (NO) donor), NG-nitro-L-arginine methyl esters (L-NAME; an inhibitor of NO synthase (NOS)), methylene blue (MB; an inhibitor of cyclic-guanosine monophosphate (cGMP) pathway), or their combination also caused significant (P<0.05) change in the intensity of the MEMC antinociception. In conclusion, the MEMC antinociceptive activity involves activation of the peripheral and central mechanisms, and modulation via, partly, the opioid receptors and NO/cGMP pathway.

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Soluble Guanylate Cyclase Stimulators and Activators: Where are We and Where to Go?

Mini-Reviews in Medicinal Chemistry ◽

10.2174/1389557519666190730110600 ◽

2019 ◽

Vol 19 (18) ◽

pp. 1544-1557 ◽

Cited By ~ 6

Author(s):

Sijia Xiao ◽

Qianbin Li ◽

Liqing Hu ◽

Zutao Yu ◽

Jie Yang ◽

...

Keyword(s):

Guanylate Cyclase ◽

Soluble Guanylate Cyclase ◽

Muscle Relaxation ◽

Cyclic Guanosine Monophosphate ◽

Guanosine Monophosphate ◽

Smooth Muscle Relaxation ◽

Secondary Messenger ◽

Physiological Processes ◽

Cgmp Pathway ◽

Preclinical And Clinical Studies

Soluble Guanylate Cyclase (sGC) is the intracellular receptor of Nitric Oxide (NO). The activation of sGC results in the conversion of Guanosine Triphosphate (GTP) to the secondary messenger cyclic Guanosine Monophosphate (cGMP). cGMP modulates a series of downstream cascades through activating a variety of effectors, such as Phosphodiesterase (PDE), Protein Kinase G (PKG) and Cyclic Nucleotide-Gated Ion Channels (CNG). NO-sGC-cGMP pathway plays significant roles in various physiological processes, including platelet aggregation, smooth muscle relaxation and neurotransmitter delivery. With the approval of an sGC stimulator Riociguat for the treatment of Pulmonary Arterial Hypertension (PAH), the enthusiasm in the discovery of sGC modulators continues for broad clinical applications. Notably, through activating the NO-sGC-cGMP pathway, sGC stimulator and activator potentiate for the treatment of various diseases, such as PAH, Heart Failure (HF), Diabetic Nephropathy (DN), Systemic Sclerosis (SS), fibrosis as well as other diseases including Sickle Cell Disease (SCD) and Central Nervous System (CNS) disease. Here, we review the preclinical and clinical studies of sGC stimulator and activator in recent years and prospect for the development of sGC modulators in the near future.

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The constitutively active PKG II mutant effectively inhibits gastric cancer development via a blockade of EGF/EGFR-associated signalling cascades

Therapeutic Advances in Medical Oncology ◽

10.1177/1758834017751635 ◽

2018 ◽

Vol 10 ◽

pp. 175883401775163 ◽

Cited By ~ 7

Author(s):

Yan Wu ◽

Miaomiao Yuan ◽

Wenbin Su ◽

Miaolin Zhu ◽

Xiaoyuan Yao ◽

...

Keyword(s):

Growth Factor Receptor ◽

Cyclic Guanosine Monophosphate ◽

Inhibitory Effect ◽

Guanosine Monophosphate ◽

Tumour Development ◽

Gastric Tumour ◽

Signalling Cascades ◽

Constitutively Active

Type II cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG II) is a membrane-anchored enzyme expressed mainly in the intestinal mucosa and the brain, and is associated with various physiological or pathological processes. Upregulation of PKG II is known to induce apoptosis and inhibit proliferation and metastasis of cancer cells. The inhibitory effect of PKG II has been shown to be dependent on the inhibition of the activation of epidermal growth factor receptor (EGFR) and blockade of EGFR downstream signal transduction in vitro. However, it remains unclear whether similar phenomena/mechanisms exist in vivo and whether these effects are independent of cGMP or cGMP analogues. In the present work, nude mice with transplanted orthotopic tumours were infected with adenovirus encoding cDNA of constitutively active PKG II mutant (Ad-a-PKG II) and the effect of constitutively active PKG II (a-PKG II) on tumour development was detected. The results showed that a-PKG II effectively ameliorated gastric tumour development through delaying the growth, inducing the apoptosis, and inhibiting the metastasis and angiogenesis. The effect was related to blockade of EGFR activation and abrogation of the downstream signalling cascades. These findings provide novel insight which will benefit the development of new cancer therapies.

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Increased nitric oxide production in platelets from severe chronic renal failure patients

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y10-111 ◽

2011 ◽

Vol 89 (2) ◽

pp. 97-102 ◽

Cited By ~ 3

Author(s):

Mariana Alves de Sá Siqueira ◽

Tatiana M.C. Brunini ◽

Natália Rodrigues Pereira ◽

Marcela Anjos Martins ◽

Monique Bandeira Moss ◽

...

Keyword(s):

Nitric Oxide ◽

Renal Failure ◽

Chronic Renal Failure ◽

Platelet Aggregation ◽

Plasma Levels ◽

Cyclic Guanosine Monophosphate ◽

Guanosine Monophosphate ◽

No Production ◽

Dialysis Treatment ◽

Cgmp Pathway

Nitric oxide (NO) production occurs through oxidation of the amino acid l-arginine by NO synthase (NOS). NO inhibits platelet activation by increasing the levels of cyclic guanosine monophosphate (cGMP), thus maintaining vascular homeostasis. Our group previously demonstrated ( da Silva et al. 2005 ) an enhancement of the l-arginine–NO–cGMP pathway in platelets taken from chronic renal failure (CRF) patients on haemodialysis associated with reduced platelet aggregation. We investigate the platelet l-arginine–NO–cGMP pathway, platelet function, and inflammation from patients in CRF on conservative treatment. A total of 42 CRF patients and 42 controls (creatinine clearance = 27 ± 3 vs. 93 ± 1 mL per min per 1.73 m2, respectively) participated in this study. NOS activity and expression and cGMP concentration were measured in platelets. Platelet aggregation induced by collagen or ADP was evaluated and plasma levels of fibrinogen were determined by the Clauss method. A marked increase in basal NOS activity was seen in undialysed CRF patients compared with controls, accompanied by an elevation of fibrinogen plasma levels. There were no differences in expression of NOS and in cGMP levels. In this context, platelet aggregation was not affected. We provide the first evidence of increased intraplatelet NO biosynthesis in undialysed CRF patients, which can be an early marker of future haemostatic abnormalities during dialysis treatment.

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cGAS-mediated autophagy protects the liver from ischemia-reperfusion injury independently of STING

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00326.2017 ◽

2018 ◽

Vol 314 (6) ◽

pp. G655-G667 ◽

Cited By ~ 20

Author(s):

Zhao Lei ◽

Meihong Deng ◽

Zhongjie Yi ◽

Qian Sun ◽

Richard A. Shapiro ◽

...

Keyword(s):

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Adenosine Monophosphate ◽

Cyclic Guanosine Monophosphate ◽

Protective Role ◽

Guanosine Monophosphate ◽

Independent Manner

Liver ischemia-reperfusion (I/R) injury occurs through induction of oxidative stress and release of damage-associated molecular patterns (DAMPs), including cytosolic DNA released from dysfunctional mitochondria or from the nucleus. Cyclic guanosine monophosphate–adenosine monophosphate (cGAMP) synthase (cGAS) is a cytosolic DNA sensor known to trigger stimulator of interferon genes (STING) and downstream type 1 interferon (IFN-I) pathways, which are pivotal innate immune system responses to pathogen. However, little is known about the role of cGAS/STING in liver I/R injury. We subjected C57BL/6 (WT), cGAS knockout (cGAS−/−), and STING-deficient (STINGgt/gt) mice to warm liver I/R injury and that found cGAS−/− mice had significantly increased liver injury compared with WT or STINGgt/gt mice, suggesting a protective effect of cGAS independent of STING. Liver I/R upregulated cGAS in vivo and also in vitro in hepatocytes subjected to anoxia/reoxygenation (A/R). We confirmed a previously published finding that hepatocytes do not express STING under normoxic conditions or after A/R. Hepatocytes and liver from cGAS−/− mice had increased cell death and reduced induction of autophagy under hypoxic conditions as well as increased apoptosis. Protection could be restored in cGAS−/− hepatocytes by overexpression of cGAS or by pretreatment of mice with autophagy inducer rapamycin. Our findings indicate a novel protective role for cGAS in the regulation of autophagy during liver I/R injury that occurs independently of STING. NEW & NOTEWORTHY Our studies are the first to document the important role of cGAS in the acute setting of sterile injury induced by I/R. Specifically, we provide evidence that cGAS protects liver from I/R injury in a STING-independent manner.

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Platelet NAD(P)H-oxidase–generated ROS production regulates αIIbβ3-integrin activation independent of the NO/cGMP pathway

Blood ◽

10.1182/blood-2005-03-1047 ◽

2005 ◽

Vol 106 (8) ◽

pp. 2757-2760 ◽

Cited By ~ 149

Author(s):

Antonija Jurak Begonja ◽

Stepan Gambaryan ◽

Jörg Geiger ◽

Barsom Aktas ◽

Miroslava Pozgajova ◽

...

Keyword(s):

Thrombus Formation ◽

Shape Change ◽

Nicotinamide Adenine Dinucleotide Phosphate ◽

Cyclic Guanosine Monophosphate ◽

Dense Granule ◽

Guanosine Monophosphate ◽

Integrin Activation ◽

Diphenylene Iodonium ◽

Cgmp Pathway ◽

Αiibβ3 Integrin

AbstractPlatelets play a crucial role in the physiology of primary hemostasis and pathophysiologic processes such as arterial thrombosis. Accumulating evidence suggests a role of reactive oxygen species (ROSs) in platelet activation. Here we show that platelets activated with different agonists produced intracellular ROSs, which were reduced by reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) oxidase inhibitors and superoxide scavengers. In addition, we demonstrate that ROSs produced in platelets significantly affected αIIbβ3 integrin activation but not alpha and dense granule secretion and platelet shape change. Thrombin-induced integrin αIIbβ3 activation was significantly decreased after pretreatment of platelets with NAD(P)H oxidase inhibitors (diphenylene iodonium [DPI] [45% ± 9%] and apocynin [43% ± 11%]) and superoxide scavengers (tiron [60% ± 9%] and Mn(III)tetrakis (1-methyl-4-pyridyl)porphyrin [MnTMPyP] [70% ± 6%]). These inhibitors also reduced platelet aggregation and thrombus formation on collagen under high shear and achieved their effects independent of the nitric oxide/cyclic guanosine monophosphate (NO/cGMP) pathway.

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Abstract 923: Dissociation Between Superoxide Accumulation And Nitroglycerin Induced Tolerance

Circulation ◽

10.1161/circ.116.suppl_16.ii_181-c ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Vamsi K Addanki ◽

Pei-Suen Tsou ◽

Ho-Leung Fung

Keyword(s):

Nadph Oxidase ◽

Ex Vivo ◽

Dry Weight ◽

Causative Factor ◽

Cyclic Guanosine Monophosphate ◽

Guanosine Monophosphate ◽

Protein Accumulation ◽

Induced Tolerance

We hypothesize that superoxide (SO) accumulation is not a critical causative factor in inducing nitroglycerin (NTG) tolerance. Using p47phox−/− and gp91−/− mice vs. their respective wild-type (WT) controls, we showed that aorta from mice null of these critical NADPH oxidase subunits exhibited similar vascular tolerance after NTG dosing (20 mg/kg sc, tid for 3 days), as indicated by their ex vivo pEC 50 and cyclic guanosine monophosphate (cGMP, pmol/mg protein) accumulation upon NTG challenge. In vitro aorta SO production (cpm/mg dry weight) was enhanced by NTG incubation both in p47phox null and WT mice (Table 1 ). Pre-exposure of isolated mice aorta to 100 microM NTG for 1 hr resulted in vascular tolerance toward NTG and increased SO accumulation. Oxypurinol (Oxy, 1mM) reduced SO but failed to attenuate vascular tolerance (Table 2 ). In LLC-PK1 cells, pre-exposure to NTG (1 microM for 4 hours) resulted in increased SO accumulation and reduced cGMP response to 3.16 microM NTG vs. vehicle control. Exposure to 1 microM angiotensin II increased SO but did not reduce cGMP response. Taken together, these results indicate that in vivo vascular NTG tolerance in mice does not require the presence of the p47phox and gp91phox subunits of NADPH oxidase, and that increased SO accumulation may be a consequence, rather than a cause, of NTG tolerance. Table 1 Table 2

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Protein kinases G are essential downstream mediators of the antifibrotic effects of sGC stimulators

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2017-212489 ◽

2018 ◽

Vol 77 (3) ◽

pp. 459-459 ◽

Cited By ~ 21

Author(s):

Alexandru-Emil Matei ◽

Christian Beyer ◽

Andrea-Hermina Györfi ◽

Alina Soare ◽

Chih-Wei Chen ◽

...

Keyword(s):

Protein Kinases ◽

Transforming Growth Factor ◽

Soluble Guanylate Cyclase ◽

Cyclic Guanosine Monophosphate ◽

Transforming Growth Factor Β1 ◽

Guanosine Monophosphate ◽

Dependent Manner ◽

Erk Phosphorylation ◽

Sgc Stimulators

ObjectivesStimulators of soluble guanylate cyclase (sGC) are currently investigated in clinical trials for the treatment of fibrosis in systemic sclerosis (SSc). In this study, we aim to investigate the role of protein kinases G (PKG) as downstream mediators of sGC–cyclic guanosine monophosphate (cGMP) in SSc.MethodsMice with combined knockout of PKG1 and 2 were challenged with bleomycin and treated with the sGC stimulator BAY 41-2272. Fibroblasts were treated with BAY 41-2272 and with the PKG inhibitor KT 5823.ResultsPKG1 and 2 are upregulated in SSc in a transforming growth factor-β1 (TGFβ1)-dependent manner, as an attempt to compensate for the decreased signalling through the sGC–cGMP–PKG pathway. Inhibition or knockout of PKG1 and 2 abrogates the inhibitory effects of sGC stimulation on fibroblast activation in a SMAD-independent, but extracellular signal-regulated kinase (ERK)-dependent manner. In vivo, sGC stimulation fails to prevent bleomycin-induced fibrosis in PKG1 and 2 knockout mice.ConclusionsOur data provide evidence that PKGs are essential mediators of the antifibrotic effects of sGC stimulators through interfering with non-canonical TGFβ signalling. TGFβ1 promotes its profibrotic effects through inhibition of sGC–cGMP–PKG signalling, sGC stimulation exerts its antifibrotic effects by inhibition of TGFβ1-induced ERK phosphorylation.

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Riociguat for treatment of pulmonary hypertension in COPD: a translational study

European Respiratory Journal ◽

10.1183/13993003.02445-2018 ◽

2019 ◽

Vol 53 (6) ◽

pp. 1802445 ◽

Cited By ~ 8

Author(s):

Alexandra Pichl ◽

Natascha Sommer ◽

Mariola Bednorz ◽

Michael Seimetz ◽

Stefan Hadzic ◽

...

Keyword(s):

Pulmonary Hypertension ◽

Cyclic Guanosine Monophosphate ◽

Guanosine Monophosphate ◽

Cigarette Smoke Exposure ◽

Chronic Obstructive ◽

Obstructive Pulmonary Disease ◽

Translational Study ◽

Copd Patients

Chronic obstructive pulmonary disease (COPD), which comprises the phenotypes of chronic bronchitis and emphysema, is often associated with pulmonary hypertension (PH). However, currently, no approved therapy exists for PH-COPD. Signalling of the nitric oxide (NO)–cyclic guanosine monophosphate (cGMP) axis plays an important role in PH and COPD.We investigated the treatment effect of riociguat, which promotes the NO–cGMP pathway, in the mouse model of smoke-induced PH and emphysema in a curative approach, and retrospectively analysed the effect of riociguat treatment on PH in single patients with PH-COPD.In mice with established PH and emphysema (after 8 months of cigarette smoke exposure), riociguat treatment for another 3 months fully reversed PH. Moreover, histological hallmarks of emphysema were decreased. Microarray analysis revealed involvement of different signalling pathways, e.g. related to matrix metalloproteinases (MMPs). MMP activity was decreased in vivo by riociguat. In PH-COPD patients treated with riociguat (n=7), the pulmonary vascular resistance, airway resistance and circulating MMP levels decreased, while oxygenation at rest was not significantly changed.Riociguat may be beneficial for treatment of PH-COPD. Further long-term prospective studies are necessary to investigate the tolerability, efficacy on functional parameters and effect specifically on pulmonary emphysema in COPD patients.

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