Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Evidence implicates hyperglycemia-derived oxygen free radicals as mediators of diabetic complications. However, intervention studies with classic antioxidants, such as vitamin E, failed to demonstrate any beneficial effect. Recent studies demonstrate that a single hyperglycemia-induced process of overproduction of superoxide by the mitochondrial electron-transport chain seems to be the first and key event in the activation of all other pathways involved in the pathogenesis of diabetic complications. These include increased polyol pathway flux, increased advanced glycosylation end product formation, activation of protein kinase C, and increased hexosamine pathway flux. Superoxide overproduction is accompanied by increased nitric oxide generation, due to an endothelial NOS and inducible NOS uncoupled state, a phenomenon favoring the formation of the strong oxidant peroxynitrite, which in turn damages DNA. DNA damage is an obligatory stimulus for the activation of the nuclear enzyme poly(ADP-ribose) polymerase. Poly(ADP-ribose) polymerase activation in turn depletes the intracellular concentration of its substrate NAD(+), slowing the rate of glycolysis, electron transport, and ATP formation, and produces an ADP-ribosylation of the GAPDH. These processes result in acute endothelial dysfunction in diabetic blood vessels that, convincingly, also contributes to the development of diabetic complications. These new findings may explain why classic antioxidants, such as vitamin E, which work by scavenging already-formed toxic oxidation products, have failed to show beneficial effects on diabetic complications and may suggest new and attractive "causal" antioxidant therapy. New low-molecular mass compounds that act as SOD or catalase mimetics or L-propionyl-carnitine and lipoic acid, which work as intracellular superoxide scavengers, improving mitochondrial function and reducing DNA damage, may be good candidates for such a strategy, and preliminary studies support this hypothesis. This "causal" therapy would also be associated with other promising tools such as LY 333531, PJ34, and FP15, which block the protein kinase beta isoform, poly(ADP-ribose) polymerase, and peroxynitrite, respectively. While waiting for these focused tools, we may have other options: thiazolinediones, statins, ACE inhibitors, and angiotensin 1 inhibitors can reduce intracellular oxidative stress generation, and it has been suggested that many of their beneficial effects, even in diabetic patients, are due to this property.
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PMID:New insights on oxidative stress and diabetic complications may lead to a "causal" antioxidant therapy. 1271 23

Nitric oxide (NO) synthase (NOS) catalyzes the oxidation of L-arginine to NO. NO plays a crucial role in regulating various physiological functions, possibly including junction dynamics via its effects on cAMP and cGMP, which are known modulators of tight junction (TJ) dynamics. Although inducible NOS (iNOS) and endothelial NOS (eNOS) are found in the testis and have been implicated in the regulation of spermatogenesis, their role(s) in TJ dynamics, if any, is not known. When Sertoli cells were cultured at 0.5-1.2 x 10(6) cells/cm(2) on Matrigel-coated dishes or bicameral units, functional TJ barrier was formed when the barrier function was assessed by quantifying transepithelial electrical resistance across the cell epithelium. The assembly of the TJ barrier was shown to associate with a significant plummeting in the levels of iNOS and eNOS, seemingly suggesting that their presence by producing NO might perturb TJ assembly. To further confirm the role of NOS on the TJ barrier function in vitro, zinc (II) protoporphyrin-IX (ZnPP), an NOS inhibitor and a soluble guanylate cyclase inhibitor, was added to the Sertoli cell cultures during TJ assembly. Indeed, ZnPP was found to facilitate the assembly and maintenance of the Sertoli cell TJ barrier, possibly by inducing the production of TJ-associated proteins, such as occludin. Subsequent studies by immunoprecipitation and immunoblotting have shown that iNOS and eNOS are structurally linked to TJ-integral membrane proteins, such as occludin, and cytoskeletal proteins, such as actin, vimentin, and alpha-tubulin. When the cAMP and cGMP levels in these ZnPP-treated samples were quantified, a ZnPP-induced reduction of intracellular cGMP, but not cAMP, was indeed detected. Furthermore, 8-bromo-cGMP, a cell membrane-permeable analog of cGMP, could also perturb the TJ barrier dose dependently similar to the effects of 8-bromo-cAMP. KT-5823, a specific inhibitor of protein kinase G, was shown to facilitate the Sertoli cell TJ barrier assembly. Cytokines, such as TGF-beta and TNF-alpha, known to perturb the Sertoli cell TJ barrier, were also shown to stimulate Sertoli cell iNOS and eNOS expression dose dependently in vitro. Collectively, these results illustrate NOS is an important physiological regulator of TJ dynamics in the testis, exerting its effects via the NO/soluble guanylate cyclase/cGMP/protein kinase G signaling pathway.
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PMID:Regulation of Sertoli cell tight junction dynamics in the rat testis via the nitric oxide synthase/soluble guanylate cyclase/3',5'-cyclic guanosine monophosphate/protein kinase G signaling pathway: an in vitro study. 1281 May 68

Nitric oxide (NO) induced by bacterial lipopolysaccharide (LPS) plays a critical role in various patho-physiological implications, such as atherosclerosis, vasculitis and septic shock. In addition, cAMP-responsive element binding protein (CREB), an important transcription factor for cell differentiation, has been shown to be involved in atherosclerogenesis in VSMCs. Here we investigated the possibility whether LPS-induced NO signaling led to phosphorylation of cAMP-responsive element binding protein on Serine-133 (CREBSer-133) in cultured vascular smooth muscle cells (VSMCs) from rats. Addition of LPS (1-10 microg/ml) for 48 hours increased not only the production NO, but also the phosphorylation of CREBSer-133. The use of NOS inhibitor (100-500 microM L-NAME) blocked the magnitudes of both LPS-induced NO production and CREBSer-133 phosphorylation. In addition, either a guanylyl cyclase (GC) inhibitor (30 microM ODQ) or a cGMP-dependent protein kinase (PKG) inhibitor (20 microM (Rp)-8-pCPT-cGMPs) significantly attenuated the magnitudes of LPS-induced CREBSer-133 phosphorylation, suggesting the involvement of NO-GC-PKG signaling. Thus, the present study suggests that NO-mediated signaling activated by bacterial LPS, at least in part, enhance CREBSer-133 phosphorylation in cultured VSMCs. The findings here may provide not only signaling pathway involved in VSMC differentiation during inflammatory response, but also new insight into possible therapeutic intervention.
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PMID:Enhancement of CREBSerine-133 phosphorylation through nitric oxide-mediated signaling induced by bacterial lipopolysaccharide in vascular smooth muscle cells from rats. 1281 20

It has been shown that the NO pathway plays a major role in restraint stress-induced fever, and that the neuronal nitric oxide synthase (nNOS) seems to be the NOS isoform that accounts for the pyretic effect of NO in psychological stress-induced fever. However, no information exists as to localization of the nNOS, i.e., in the peripheral or in the central nervous system (CNS). Thus, in the present study, we tested the hypothesis that NO arising from nNOS in the CNS participates in restraint stress-induced fever. Moreover, we also assessed the involvement of cyclic guanosine monophosphate (cGMP) in the mediation of the NO effects. To this end, intracerebroventricular S-methyl-L-thiocitrulline (SMTC; a selective nNOS inhibitor), sodium nitroprusside (an NO donor) or Rp-guanosine 3',5'-cyclic monophosphothioate triethylamine (Rp-cGMPS; a specific membrane-permeable inhibitor of the activation by cGMP of cGMP-dependent protein kinase) were injected, and the colonic temperature (T(c)) of restrained or unrestrained rats was recorded. Both SMTC (0.5 mg/mul) and Rp-cGMPS (10 mug/mul) intracerebroventricular injections enhanced restraint fever, whereas intracerebroventricular injections of sodium nitroprusside (100 mug/mul) reduced this response. These data indicate that NO produced in the CNS, arising from nNOS and acting via cGMP, plays an antipyretic role in the restraint stress-induced fever.
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PMID:Central nNOS is involved in restraint stress-induced fever: evidence for a cGMP pathway. 1456 19

Neuronal nitric-oxide synthase (nNOS) is a constitutively expressed enzyme responsible for the production of nitric oxide (NO*) from l-arginine and O2. Nitric oxide is an intra- and intercellular messenger that mediates a diversity of signaling pathways in target cells. In the absence of l-arginine, nNOS has been shown to generate superoxide (O2*). Superoxide, either directly or through its self-dismutation to H2O2, is likewise believed to be a cell-signaling agent. Because nNOS can generate NO* and O2*, we examined the activation of cellular signal transduction pathways in nNOS-transfected cells grown in the presence or absence of l-arginine. Spin trapping/EPR spectroscopy confirmed that stimulated nNOS-transfected cells grown in an l-arginine environment secreted NO* into the surrounding milieu. Production of NO* blocked Ca2+ ionophore-induced activation of the ERK1/2 through a mechanism involving inhibition of the Ras G-protein and Raf-1 kinase. In contrast, ERK activation was largely unaffected in nNOS-transfected cells grown in l-arginine-free media. Inhibition of nNOS-generated NO* with the competitive NOS inhibitor, NG-nitro-l-arginine methyl ester, in cells grown in l-arginine restored ERK1/2 activation to levels similar to that found when nNOS was activated in l-arginine-free media. These findings indicate that nNOS can differentially regulate the ERK signal transduction pathway in a manner dependent on the presence of l-arginine and the production of NO*.
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PMID:Nitric oxide inhibition of ERK1/2 activity in cells expressing neuronal nitric-oxide synthase. 1460 25

Banhabackchulchunmatang (BCT) is a widely used herbal medicine with vasodilatory actions. In the present study, we investigated the subcellular mechanisms of its vascular actions. Both in the presence and absence of endothelium, BCT relaxed vascular strips precontracted with phenylephrine, but the magnitude of relaxation was greater in the presence of endothelium. The relaxation was inhibited by either L-NAME, an NOS inhibitor, or methylene blue, a cGMP inhibitor, indicating the involvement of nitric oxide (NO). The involvement of NO was supported by the increased formation of nitrite from human umbilical vein endothelial cells in the presence of BCT. In vascular strips, BCT lowered the phosphorylation level of the 20 kDa myosin light chains. BCT also directly inhibited phenylephrine-induced protein kinase Calpha (PKCalpha) translocation in freshly isolated single ferret portal vein smooth muscle cells. Together, these effects are likely to contribute to the vasodilatory actions of BCT.
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PMID:Vasodilation by banhabackchulchunmatang, a Chinese medicine, is associated with negative modulation of PKCalpha activation and NO production. 1465 65

Hydrophobic bile acids such as deoxycholate are known tumor promoters in the gastrointestinal tract. We have previously shown that deoxycholate induces apoptosis in colon epithelial cells and that these cells can be made resistant to deoxycholate-induced apoptosis. We now show that the nitric oxide synthase/nitric oxide/guanylate cyclase/cyclic guanosine monophosphate/cGMP-activated protein kinase (NOS/NO/GC/cGMP/PKG) signaling module contributes, in part, to the observed resistance of the cultured DOC-resistant colon epithelial cells (HCT-116R) using pharmacological inhibitors/antagonists (NS2028, Rp-8pCPT-cGMP, KT5823) of members of this signaling module. A novel finding from this study is the caspase-6 mediated cleavage of guanylate cyclase alpha 1 during deoxycholate-induced apoptosis of deoxycholate-sensitive HCT-116SA cells and the absence of guanylate cyclase alpha 1 cleavage in deoxycholate-treated HCT-116R resistant cells using Western blot analyses. This cleavage was specific to caspases as lysosomal, proteasomal, serine protease, cathepsin and calpain inhibitors failed to prevent the cleavage, whereas a general caspase inhibitor and a specific caspase-6 inhibitor did prevent guanylate cyclase alpha 1 cleavage.
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PMID:Caspase-6 mediated cleavage of guanylate cyclase alpha 1 during deoxycholate-induced apoptosis: protective role of the nitric oxide signaling module. 1501 62

The aim of this study was to analyse the possible influence of cyclic AMP-protein kinase A (cAMP-PKA) activation on neuronal nitric oxide (NO) release induced by electrical field stimulation in mesenteric arteries from Wistar Kyoto (WKY) rats. Western blot experiments demonstrated the expression of neuronal NO synthase (nNOS) in mesenteric artery from WKY rats; however, electrical field stimulation alone did not induce detectable NO release. Preincubation with forskolin allowed NO release induced by electrical field stimulation, which was abolished by: the neuronal toxine tetrodotoxin, the nNOS inhibitors 7-nitroindazole or N(omega)-propil-l-arginine (NPLA), and the PKA inhibitors N-(2-(p-Bromocinnamylamino) ethyl 5-isoquinolinesulfonamide hydrochloride (H-89) or (9R,10S,12S)-2,3,9,10,11, 12-Hexahydro-10-9-methyl-1-oxo-9,12-epoxy-1H-diindolo(1,2,3-fg:3,2,1k)pyrrolo(3,4-l)(1,6) benzodiazocine-10-carboxylic acid hexyl ester (KT-5720). Preincubation with prostacyclin also allowed the NO release induced by electrical field stimulation which was significantly decreased by: the neuronal toxine tetrodotoxin, the nNOS inhibitors 7-nitroindazole or NPLA, and the PKA inhibitors H-89 or KT-5720. The NOS inhibitor N(omega)-nitro-l-arginine methyl ester (l-NAME) did not modify the vasoconstrictor response induced by electrical field stimulation. However, in the presence of forskolin or prostacyclin, l-NAME increased the vasoconstrictor response to electrical field stimulation. These results indicate that forskolin and prostacyclin allow neuronal NO release induced by electrical field stimulation through a mechanism involving cAMP-PKA activation in rat mesenteric arteries.
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PMID:Protein kinase A increases electrical stimulation-induced neuronal nitric oxide release in rat mesenteric artery. 1503 89

The present study tests the hypothesis that cerebral tissue hypoxia results in increased Ca(2+)/calmodulin (CaM) kinase kinase activity and that the administration of nitric oxide synthase inhibitors (N-nitro-l-arginine [NNLA], or 7-nitroindazole sodium [7-NINA]) prior to the onset of hypoxia will prevent the hypoxia-induced increase in the enzyme activity. To test this hypothesis, CaM kinase kinase and CaM kinase IV activities were determined in normoxic, hypoxic, NNLA-treated hypoxic, and 7-NINA-treated hypoxic piglets. Hypoxia was induced (FiO(2)=0.05-0.08x1 h) and confirmed biochemically by tissue levels of ATP and phosphocreatine. CaM kinase kinase activity was determined in a medium containing protein kinase and phosphatase inhibitors, calmodulin, and a specifically designed CaM kinase kinase target peptide. CaM kinase IV activity was determined by (33)P-incorporation into syntide-2 in a buffer containing protein kinase and phosphatase inhibitors. Compared with normoxic animals, ATP and phosphocreatine levels were significantly lower in all hypoxic piglets whether or not pretreated with nitric oxide synthase inhibitors. There was a significant difference among CaM kinase kinase activity (pmol/mg protein/min) in normoxic (76.84+/-14.1), hypoxic (138.86+/-18.2, P<0.05 vs normoxia), NNLA-pretreated hypoxic (91.34+/-19.3; P=NS vs normoxia, P<0.05 vs hypoxia) and 7-NINA-pretreated hypoxic animals (100.12+/-23.3; P=NS vs normoxia, P<0.05 vs hypoxia). There was a significant difference among CaM kinase IV activity (pmol/mg protein/min) in normoxia (1270.80+/-126.1), hypoxia (2680.80+/-136.7; P<0.05 vs normoxia), NNLA-pretreated hypoxia (1666.00+/-154.8; P<0.05 vs normoxia, P<0.05 vs hypoxia), and 7-NINA-pretreated hypoxic (1712.9+/-231.5; P=NS vs normoxia, P<0.05 vs hypoxia). We conclude that the hypoxia-induced increase in CaM kinase kinase and CaM kinase IV activity is mediated by neuronal NOS-derived NO.
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PMID:Effect of neuronal nitric oxide synthase inhibition on CA2+/calmodulin kinase kinase and CA2+/calmodulin kinase IV activity during hypoxia in cortical nuclei of newborn piglets. 1512 Aug 53

The cardiac effects of adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) as well as the possible signaling pathways were investigated. In the isolated perfused rat heart, infusion of AM (10(-11) to 10(-8) M) and PAMP(10(-11) to 10(-8) M) for 10 min, alone or in combination, induced concentration-dependent decreases in the left ventricular pressure (LVP), LVP +/- dp/dtmax of the hearts. The effects were attenuated by Nomega-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) synthase. ADM and PAMP alone or in combinations increased the coronary fluid (CF), which could be antagonized by L-NAME. Pretreatment of H89, an inhibitor of protein kinase A (PKA), failed to alter the AM- or PAMP-induced decreases in LVP and LVP +/- dp/dtmax, but further promoted the AM or PAMP increased CF. The cAMP content in left cardiac ventricle was increased significantly by ADM infusions but not by PAMP. There was no statistical difference in cAMP contents with ADM administrated alone from those combined with ADM and PAMP. In conclusion, this study reveals that ADM and PAMP infused alone or in combinations inhibited the function of rat hearts in vitro, which may be partly involved with the NOS/NO pathway, rather than cAMP/PKA.
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PMID:Impact of nitric oxide on adrenomedullin- and proadrenomedullin N-terminal 20 peptide-induced cardiac responses: action by alone and combined administration. 1512 49


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