Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.11.12 (PKG)
 2,515 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

U73122, a phospholipase C inhibitor, dose dependently blocks the cGMP-induced Ca2+ release in sea urchin eggs and homogenates. U73122 inhibition was prevented by cotreatment with dithiothreitol (DTT), but DTT is ineffective when eggs or homogenates were pretreated with U73122. U73122 action is different from the other sulfhydryl reagents, thimerosal and N-ethylmaleimide, which cause Ca2+ release in egg homogenates at high concentration, but at lower concentration have no significant effect on cGMP-induced Ca2+ release. Histone, a reported NAD glycohydrolase (NADase) activator, was found to induce Ca2+ release in egg homogenates via the same pathway as the cGMP response, since histone-induced Ca2+ release is blocked by Rp-8-pCPT-cGMPS, a cGMP-dependent protein kinase (PKG) inhibitor, and nicotinamide, a NADase inhibitor. Histone-induced Ca2+ release is similarly blocked by U73122. The aminosteroid U73122 does not inhibit cADPR-induced Ca2+ release, which is significantly reduced by PKG inhibitors. Furthermore, U73122 has no significant effect on phorbol 12-myristate 13-acetate induced-cytoplasmic alkalinization in intact eggs, which depends on protein kinase C activity. These results suggest that U73122 does not act as a general serine-threonine protein kinase inhibitor, and the aminosteroid inhibition of the cGMP-induced Ca2+ release may interfere with ADP ribosyl cyclase activity.
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PMID:U73122 blocked the cGMP-induced calcium release in sea urchin eggs. 966 30

Long-term potentiation (LTP) is a potential cellular mechanism for learning and memory. The retrograde messenger nitric oxide (NO) is thought to induce LTP in the CA1 region of the hippocampus via activation of soluble guanylyl cyclase (sGC) and, ultimately, cGMP-dependent protein kinase (cGK). Two genes code for the isozymes cGKI and cGKII in vertebrates. The functional role of cGKs in LTP was analyzed using mice lacking the gene(s) for cGKI, cGKII, or both. LTP was not altered in the mutant mice lineages. However, LTP was reduced by inhibition of NO synthase and NMDA receptor antagonists, respectively. The reduced LTP was not recovered by the cGK-activator 8-(4 chlorophenylthio)-cGMP. Moreover, LTP was not affected by the sGC inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]-quiloxalin-1-one. In contrast, it was effectively suppressed by nicotinamide, a blocker of the ADP-ribosyltransferase. These results show that cGKs are not involved in LTP in mice and that NO induces LTP through an alternative cGMP-independent pathway, possibly ADP-ribosylation.
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PMID:Long-term potentiation in the hippocampal CA1 region of mice lacking cGMP-dependent kinases is normal and susceptible to inhibition of nitric oxide synthase. 987 Sep 37

Long-term depression (LTD) of synaptic transmission can be induced by several mechanisms, one thought to involve Ca2+-dependent activation of postsynaptic nitric oxide (NO) synthase and subsequent diffusion of NO to the presynaptic terminal. We used the stable NO donor S-nitroso-N-acetylpenicillamine (SNAP) to study the NO-dependent form of LTD at Schaffer collateral-CA1 synapses in vitro. SNAP (100 microM) enhanced the induction of LTD via a cascade that was blocked by the N-methyl-D-aspartate receptor antagonist D-2-amino-5-phosphonopentanoic acid (50 microM), NO guanylyl cyclase inhibitor 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (10 microM), and the PKG inhibitor KT5823 (1 microM). We further show that LTD induced by low-frequency stimulation in the absence of SNAP also is blocked by KT5823 or Rp-8-(4-chlorophenylthio)-guanosine 3',5'-cyclic monophosphorothioate (10 microM), cyclic guanosine 3',5' monophosphate-dependent protein kinase (PKG) inhibitors with different mechanisms of action. Furthermore SNAP-facilitated LTD was blocked when release from intracellular calcium stores was inhibited by ryanodine (10 microM). Finally, two cell-permeant antagonists of the cyclic ADP-ribose binding site on ryanodine receptors also were able to block the induction of LTD. These results support a cascade for induction of homosynaptic, NO-dependent LTD involving activation of guanylyl cyclase, production of guanosine 3',5' cyclic monophosphate and subsequent PKG activation. This process has an additional requirement for release of Ca2+ from ryanodine-sensitive stores, perhaps dependent on the second-messenger cyclic ADP ribose.
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PMID:Induction of hippocampal LTD requires nitric-oxide-stimulated PKG activity and Ca2+ release from cyclic ADP-ribose-sensitive stores. 1048 70

Estrogen increases secretion of cervical mucus in women, and the effect depends on fragmentation of the cytoskeleton. The objective of the present study was to understand the molecular mechanism of estrogen action. Treatment of human cervical epithelial cells with 17beta-estradiol, sodium nitroprusside (SNP), or 8-bromoguanosine 3', 5'-cyclic monophosphate (8-Br-cGMP) increased cellular monomeric G-actin and decreased polymerized F-actin. The effects of estradiol were blocked by tamoxifen, by the guanylate cyclase inhibitor LY-83583, and by the cGMP-dependent protein kinase inhibitor KT-5823. The effects of SNP were blocked by LY-83583 and KT-5823, while the effects of 8-Br-cGMP were blocked only by KT-5823. Treatment with phalloidin decreased paracellular permeability and G-actin. Treatment with 17beta-estradiol, SNP, or 8-Br-cGMP attenuated SNP-induced phosphorylation of [(32)P]adenylate NAD in vitro: tamoxifen blocked the effect of estrogen; LY-83583 blocked the effect of SNP but not that of 8-Br-cGMP, while KT-5823 blocked effects of both SNP and 8-Br-cGMP. These results indicate that estrogen, nitric oxide (NO), and cGMP stimulate actin depolymerization. A possible mechanism is NO-induced, cGMP-dependent protein kinase augmentation of ADP-ribosylation of monomeric actin.
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PMID:cGMP-dependent ADP depolymerization of actin mediates estrogen increase in cervical epithelial permeability. 1107 20

BAY 41-8543 is a novel, highly specific and so far the most potent NO-independent stimulator of sGC. Here we report the effects of BAY 41-8543 on the isolated enzyme, endothelial cells, platelets, isolated vessels and Langendorff heart preparation. BAY 41-8543 stimulates the recombinant sGC concentration-dependently from 0.0001 microM to 100 microM up to 92-fold. In combination, BAY 41-8543 and NO have synergistic effects over a wide range of concentrations. Similar results are shown in implying that BAY 41-8543 stimulates the sGC directly and furthermore makes the enzyme more sensitive to its endogenous activator NO. In vitro, BAY 41-8543 is a potent relaxing agent of aortas, saphenous arteries, coronary arteries and veins with IC(50)-values in the nM range. In the rat heart Langendorff preparation, BAY 41-8543 potently reduces coronary perfusion pressure from 10(-9) to 10(-6) g ml(-1) without any effect on left ventricular pressure and heart rate. BAY 41-8543 is effective even under nitrate tolerance conditions proved by the same vasorelaxing effect on aortic rings taken either from normal or nitrate-tolerant rats. BAY 41-8543 is a potent inhibitor of collagen-mediated aggregation in washed human platelets (IC(50)=0.09 microM). In plasma, BAY 41-8543 inhibits collagen-mediated aggregation better than ADP-induced aggregation, but has no effect on the thrombin pathway. BAY 41-8543 is also a potent direct stimulator of the cyclic GMP/PKG/VASP pathway in platelets and synergizes with NO over a wide range of concentrations. These results suggest that BAY 41-8543 is on the one hand an invaluable tool for studying sGC signaling in vitro and on the other hand its unique profile may offer a novel approach for treating cardiovascular diseases.
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PMID:Pharmacological actions of a novel NO-independent guanylyl cyclase stimulator, BAY 41-8543: in vitro studies. 1181 68

In studies on human platelets, nitroprusside (NP) alone at 1-10 micromol/l increased platelet cyclic AMP (cAMP) by 40-70%, whereas increases in cyclic GMP (cGMP) were much larger in percentage though not in concentration terms. Collagen enhanced these increases in cAMP up to fourfold, without affecting cGMP. This effect was partly prevented by indomethacin or aspirin, indicating that platelet cyclo-oxygenase products acted synergistically with NP to increase cAMP. ADP released from the platelets by collagen tended to restrict this cAMP accumulation. Addition of 2',5'-dideoxyadenosine (DDA), an inhibitor of adenylyl cyclase, decreased both the inhibition of collagen-induced platelet aggregation by NP and the associated accumulation of cAMP without affecting cGMP, indicating that cAMP mediates part of the inhibitory effect of NP. Unlike DDA, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of guanylyl cyclase, blocked all increases in both cGMP and cAMP caused by NP, as well as the inhibition of platelet aggregation, suggesting that cAMP accumulation was secondary to that of cGMP. Human platelet cGMP-dependent protein kinase (PKG) coelectrophoresed with the purified bovine type Ibeta isoenzyme. An inhibitor of this enzyme (Rp)-beta-phenyl-1,N2-etheno-8-bromoguanosine 3',5'-cyclic-monophosphorothioate, diminished the inhibition of collagen-induced platelet aggregation by NP, but had little additional effect when DDA was present. This showed that both PKG and cAMP participate in the inhibition of collagen-induced platelet aggregation by NP. Moreover, selective activators of PKG and cAMP-dependent protein kinases had supra-additive inhibitory effects, suggesting that an optimal inhibitory effect of NP requires simultaneous activation of both enzymes.
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PMID:Roles for both cyclic GMP and cyclic AMP in the inhibition of collagen-induced platelet aggregation by nitroprusside. 1202 40

Platelet secretion (exocytosis) is critical in amplifying platelet activation, in stabilizing thrombi, and in arteriosclerosis and vascular remodeling. The signaling mechanisms leading to secretion have not been well defined. We have shown previously that cGMP-dependent protein kinase (PKG) plays a stimulatory role in platelet activation via the glycoprotein Ib-IX pathway. Here we show that PKG also plays an important stimulatory role in mediating aggregation-dependent platelet secretion and secretion-dependent second wave platelet aggregation, particularly those induced via Gq-coupled agonist receptors, the thromboxane A2 (TXA2) receptor, and protease-activated receptors (PARs). PKG I knock-out mouse platelets and PKG inhibitor-treated human platelets showed diminished aggregation-dependent secretion and also showed a diminished secondary wave of platelet aggregation induced by a TXA2 analog and thrombin receptor-activating peptides that were rescued by the granule content ADP. Low dose collagen-induced platelet secretion and aggregation were also reduced by PKG inhibitors. Furthermore PKG I knockout and PKG inhibitors significantly attenuated activation of the Gi pathway that is mediated by secreted ADP. These data unveil a novel PKG-dependent platelet secretion pathway and a mechanism by which PKG promotes platelet activation.
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PMID:A platelet secretion pathway mediated by cGMP-dependent protein kinase. 1528 Mar 95

The NO/cGMP signalling pathway strongly inhibits agonist-induced platelet aggregation. However, the molecular mechanisms involved are not completely defined. We have studied NO/cGMP effects on the activity of Rap 1, an abundant guanine-nucleotidebinding protein in platelets. Rap 1-GTP levels were reduced by NO-donors and activators of NO-sensitive soluble guanylyl cyclase. Four lines of evidence suggest that NO/cGMP effects are mediated by cGMP-dependent protein kinase (cGKI): (i) Rap 1 inhibition correlated with cGKI activity as measured by the phosphorylation state of VASP, an established substrate of cGKI, (ii) 8-pCPT-cGMP, a membrane permeable cGMP-analog and activator of cGKI, completely blocked Rap1 activation, (iii) Rp-8pCPT-cGMPS, a cGKI inhibitor, reversed NO effects and (iv) expression of cGKI in cGKI-deficient megakaryocytes inhibited Rap1 activation. NO/cGMP/cGKI effects were independent of the type of stimulus used for Rap1 activation. Thrombin-,ADP- and collagen-induced formation of Rap 1-GTP in platelets as well as turbulence-induced Rap 1 activation in megakaryocytes were inhibited. Furthermore, cGKI inhibited ADP-induced Rap 1 activation induced by the Galpha(i)-coupled P2Y12 receptor alone, i.e. independently of effects on Ca2+-signalling. From these studies we conclude that NO/cGMP inhibit Rap 1 activation in human platelets and that this effect is mediated by cGKI. Since Rap1 controls the function of integrin alpha(IIb)beta3, we propose that Rap 1 inhibition might play a central role in the anti-aggregatory actions of NO/cGMP.
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PMID:The NO/cGMP pathway inhibits Rap 1 activation in human platelets via cGMP-dependent protein kinase I. 1571 49

Anoikis is an essential process in which a loss of adhesion to the substratum alters intracellular signaling pathways that lead to apoptosis. Using phosphorylation of vasodilator stimulated phosphoprotein (VASP) as an indicator of cGMP-dependent protein kinase (PKG) activity in vivo, it was found that suspension of the colon epithelial cell line (CCD841) leads to rapid and transient activation of PKG that lasted several hours. The colon carcinoma lines SW480 and SW620 do not express endogenous PKG, but exogenously expressed PKG was similarly activated upon cell suspension. To determine whether PKG has a role in apoptosis following cell suspension, poly-ADP ribose polymerase (PARP) cleavage and propidium iodide staining were measured. After 24 h in suspension it was found that approximately 50% of CCD841 cells exhibited apoptosis, whereas apoptosis was not detected in either of the colon carcinoma cell lines. Inhibition of type 1 PKG by expression of a dominant negative PKG construct (G1alphaR-GFP), or by incubation with the PKG inhibitor peptide DT-2, blocked apoptosis in suspended CCD841 cells by approximately 50%. Furthermore, expression of exogenous PKG in SW620 and SW480 cells conferred partial sensitivity anoikis. Taken together these findings indicate that PKG has an important role in the induction of apoptosis following suspension of normal colon epithelial cells, and loss of PKG expression in colon tumor cells may contribute to resistance to anoikis.
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PMID:A role for cyclic-GMP dependent protein kinase in anoikis. 1613 77

The cyclic nucleotide monophosphates cAMP and cGMP play an essential role in many signaling pathways. To analyze which proteins do interact with these second messenger molecules, we developed a chemical proteomics approach using cAMP and cGMP immobilized onto agarose beads, via flexible linkers in the 2- and 8-position of the nucleotide. Optimization of the affinity pull-down procedures in lysates of HEK293 cells revealed that a large variety of proteins could be pulled down specifically. Identification of these proteins by mass spectrometry showed that many of these proteins were indeed genuine cAMP or cGMP binding proteins. However, additionally many of the pulled-down proteins were more abundant AMP/ADP/ATP, GMP/GDP/GTP, or general DNA/RNA binding proteins. Therefore, a sequential elution protocol was developed, eluting proteins from the beads using solutions containing ADP, GDP, cGMP, and/or cAMP, respectively. Using this protocol, we were able to sequentially and selectively elute ADP, GDP, and DNA binding proteins. The fraction left on the beads was further enriched, for cAMP/cGMP binding proteins. Transferring this protocol to the analysis of the cGMP/cAMP "interactome" in rat heart ventricular tissue enabled the specific pull-down of known cAMP/cGMP binding proteins such as cAMP and cGMP dependent protein kinases PKA and PKG, several phosphodiesterases and 6 AKAPs, that interact with PKA. Among the latter class of proteins was the highly abundant sphingosine kinase type1-interating protein (SKIP), recently proposed to be a potential AKAP. Further bioinformatics analysis endorses that SKIP is indeed a genuine PKA interacting protein, which is highly abundant in heart ventricular tissue.
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PMID:Analysis of the cGMP/cAMP interactome using a chemical proteomics approach in mammalian heart tissue validates sphingosine kinase type 1-interacting protein as a genuine and highly abundant AKAP. 1673 95


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