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:4.6.1.2 (guanylate cyclase)
8,497 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The addition of ANF to Percoll-purified liver plasma membranes produced a slight activation of guanylate cyclase; the ANF-stimulated cyclase activity was further increased upon the addition of ATP to the enzyme assay mixture. The effect of ATP to potentiate the cyclase activation was concentration-dependent, required Mg2+ as a divalent cation, and was seen with membranes from various tissues and cells. ATP increased the maximal velocity of the cyclase without a change in the affinity for GTP or ANF. Phosphorylation by ATP might not be involved since ANF-stimulated guanylate cyclase was enhanced by non-phosphorylating ATP analogues as well. Thus, an allosteric ATP binding site is suggested to participate in ANF-induced regulation of membrane-bound guanylate cyclase.
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PMID:Participation of adenosine 5'-triphosphate in the activation of membrane-bound guanylate cyclase by the atrial natriuretic factor. 288 66

We examined adenosine 5'-triphosphate (ATP), pertussis toxin (PT) and phorbol myristate acetate (PMA), a protein kinase C (PKC) activator, modulation of atrial natriuretic peptide (ANP)-stimulated cell-membrane guanylate cyclase (ANP-s-GC) activity and ANP stimulation of whole-cell cGMP accumulation (ANP-s-cGMP) in an ANP-receptor-transduction cell model, the human renal cell line (SK-NEP-1). Acute and long-term effects of PMA on PKC isotype activity are different: Acute (20-min) PMA activation of PKC inhibits ANP-s-cGMP and ANP-s-GC; whereas, long-term (36-h) PMA treatment inhibits slightly less by only partially down-regulating PKC activity, the type-III PKC isotype being 36-h resistant. Long-term 10(-7)M PMA treatment of cells neither affected membrane basal GC activity nor ANP-s-GC activity but partially inhibited ATP enhancement of ANP-s-GC. This partial inhibition was completely reversed by the PKC inhibitor H7 and a PKC inhibitory antibody but only partially reversed by the antibody to the catalytic domain of PKC type III. The EC50 for ATP and its non-phosphorylating analog ATP gamma S in the presence of acute PMA inhibition of ANP-s-cGMP was similar (approximately 10(-9)). This enhancement of PMA inhibition was two orders of magnitude more sensitive (EC50 10(-7)M) than inhibition of ANP-s-cGMP that we previously reported for acute PMA treatment of whole SK-NEP-1 cells. The three- to four-fold ATP enhancement of cell membrane ANP-s-GC was not blocked by 12-hour preincubation of cells with 150 ng/mL PT but was completely blocked if 2-x-10(-7)M PMA was then added for 20 minutes, indicating that acute activation of PKC by PMA does not require a functional "G-type" protein. Acute PMA inhibition of ANP-s-cGMP was reversed by permeabilizing SK-NEP-1 cells to a specific PKC inhibitory peptide, further confirming that PMA inhibition was mediated through PKC activation. These data demonstrated that ANP-s-GC and ANP-s-cGMP were modified through non-phosphorylating interactions with ATP, by multiple PMA activatable PKC isoforms, and that neither were affected by PT-sensitive guanine-nucleotide-binding (G)-protein(s).
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PMID:Adenosine 5'-triphosphate, phorbol ester, and pertussis toxin effects on atrial natriuretic peptide stimulation of guanylate cyclase in a human renal cell line. 790 11

Recently we reported that Vibrio vulnificus hemolysin, an exotoxin produced by V. vulnificus, dilates rat thoracic aorta via elevated cGMP levels without affecting nitric oxide synthase. We investigated the mechanism further by observing the guanylyl cyclase activities in cytosolic, membrane, unfractionated, or reconstituted preparations. Hemolysin did not activate guanylyl cyclase in the membrane or cytosolic fraction, while it activated guanylyl cyclase in unfractionated or reconstituted preparation. The increased activity was not inhibited by the HS-142-1, a microbial polysaccharide which antagonizes atrial natriuretic peptide receptor, or 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor. However, it was attenuated by 6-(phenylamino)-5,8-quinolinedione (LY 83.583), which inhibits the catalytic domain of both guanylyl cyclases, and by cholesterol, which blocks hemolysin-incorporation into the membrane. Removing ATP, a cofactor of particulate guanylyl cyclase, attenuated the activation and ATPgammaS, a non-phosphorylating analog, restored it. These results suggest that V. vulnificus hemolysin activates particulate guanylyl cyclase via hemolysin incorporation into the vascular smooth muscle cell membrane in cooperation with certain unidentified cytosolic component(s).
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PMID:Activation of particulate guanylyl cyclase by Vibrio vulnificus hemolysin. 998 11

C-type natriuretic peptide (CNP) is secreted by endothelial cells and has vasodilatory and antiproliferative activity against smooth muscle cells. Using defined laminar shear stress exposures of cultured bovine aortic endothelial cells, we investigated the regulation of CNP gene by PhosphorImaging the ratio of CNP mRNA to glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mRNA. A 6 h exposure to arterial shear stress of 25 dyn/cm2 caused a marked elevation (10.5 +/- 6.2-fold: n=10, p<0.001) of CNP/GAPDH mRNA ratio compared to stationary controls. Arterial shear stress was 2.6 times more potent than a venous level of shear stress of 4 dyn/cm2 in elevating the CNP/GAPDH mRNA ratio. After 6 h, CNP secretion by shear stressed BAEC was elevated over stationary controls by 3.1-fold (n=5, p<0.001) to a level of 34 +/- 7.5 pg/cm2 BAEC. Shear stress elevated CNP mRNA in the presence of L-NAME (400 microM) indicating that autocrine signaling through shear-induced NO production or guanylate cyclase activation was not involved. Similarly, the tyrosine kinase inhibitor genistein (10 microM), which can also block shear-induced NO production, had no effect on CNP mRNA induction by shear stress in BAEC. The intracellular calcium chelator BAPTA/AM (5 microM) attenuated the shear stress-induced CNP mRNA expression by 71%. Interestingly, dexamethasone (1 microM) potentiated by 2-fold the shear stress enhancement of CNP mRNA. Shear stress was a more potent inducer of CNP than either phorbol myristrate acetate or lipopolysaccharide. Hemodynamic shear stress may be an important physiological regulator of CNP expression with consequent effects on vasodilation and regulation of intimal hyperplasia.
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PMID:Shear stress induction of C-type natriuretic peptide (CNP) in endothelial cells is independent of NO autocrine signaling. 1046 26

The endocrine function of the heart is to secrete Atrial and Brain natriuretic -peptides (ANP and BNP). These peptides are biologically active via particulate guanylate cyclases which generate cyclic GMP, the second intracellular messenger. A polysaccharide antagonist, HS-142-1 has been recently described by a Japanese Group. Cyclic GMP is partly secreted from the target cells into the extra cellular medium in which its accumulation is proportional to the concentration of the natriuretic peptide. Neutral Endopeptidase (NEP) is a zinc ectoenzyme involved in the catabolism of natriuretic peptides. NEP is absent in plasma but present on the surface of endothelial and smooth muscle cells. NEP is mainly expressed at the apical pole of the epithelial cells of the proximal tubule in the nephron. Chronic increase in volume and pressure within the cardiac cavities is associated with the oversecretion of natriuretic peptides. This chronic phenomenon involves the recruitment of all the cardiac myocytes to express natriuretic peptide genes. The clinical application of this hyperplasic phenomenon is congestive heart failure, in which the plasma levels of natriuretic peptides correlate with the level of the -hemodynamic stress. Therefore the plasma levels of natriuretic peptides are good pronostic markers in both experimental and human heart failure. The degree of congestive heart failure as well as the plasma levels of ANP and BNP are also -correlated with the plasma and urinary levels of cyclic GMP. The plasma level of -cyclic GMP is correlated with the endothelial concentration of cyclic GMP but not with the cyclic GMP concentration in smooth muscle cells. From these experimental data, we can conclude that plasma cyclic GMP originates from endothelial cells and is related to particulate guanylate cyclase activity. In contrast natriuretic peptides do not modulate vascular wall cyclic GMP content. The natriuretic action of ANP is probably due to the interaction of the filtered peptide with the particulate guanylate cyclase at the apical pole of the epithelial cells. The apparition of peptiduria associated with natriuresis during NEP inhibition provides evidence of the action of the peptide in the urinary compartment. It is also by a urinary pathway via the macula densa that ANP, and its potentiation by NEP inhibition, decreases renin secretion. The fact that plasma levels of ANP and plasma and urine levels of cyclic GMP correlate with the degree of salt retention in congestive heart failure, provides evidence for chronic desensitization of the system. An up-regulation of Na(+), K(+), 2Cl(-) expression associated with experimental congestive heart failure has recently been shown. Similarly, a modulation of the different sodium transporter systems along the nephron could be one of the counter-regulations leading to desensitization to natriuretic peptides. In conclusion, natriuretic peptides are true endocrine peptides, secreted by the heart, transported in the plasma, filtered by the glomeruli and active at the nephron level. The molecular effector of ANP and cyclic GMP in the epithelial cells is probably the G-kinase II, isoform phosphorylating the cystic fibrosis transmembrane conductance regulator (CFTR). The exact mechanism of desensitization remains to be elucidated.
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PMID:[Functional compartmentation of the endocrine action of cardiac natriuretic peptides]. 1079 May 90

Circulating natriuretic peptides such as atrial natriuretic peptide (ANP) counterbalance the effects of hypertension and inhibit cardiac hypertrophy by activating cGMP-dependent protein kinase (PKG). Natriuretic peptide binding to type I receptors (NPRA and NPRB) activates their intrinsic guanylyl cyclase activity, resulting in a rapid increase in cytosolic cGMP that subsequently activates PKG. Phosphorylation of the receptor by an unknown serine/threonine kinase is required before ligand binding can activate the cyclase. While searching for downstream PKG partners using a yeast two-hybrid screen of a human heart cDNA library, we unexpectedly found an upstream association with NPRA. PKG is a serine/threonine kinase capable of phosphorylating NPRA in vitro; however, regulation of NPRA by PKG has not been previously reported. Here we show that PKG is recruited to the plasma membrane following ANP treatment, an effect that can be blocked by pharmacological inhibition of PKG activation. Furthermore, PKG participates in a ligand-dependent gain-of-function loop that significantly increases the intrinsic cyclase activity of the receptor. PKG translocation is ANP-dependent but not nitric oxide-dependent. Our results suggest that anchoring of PKG to NPRA is a key event after ligand binding that determines distal effects. As such, the NPRA-PKG association may represent a novel mechanism for compartmentation of cGMP-mediated signaling and regulation of receptor sensitivity.
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PMID:Atrial natriuretic peptide induces natriuretic peptide receptor-cGMP-dependent protein kinase interaction. 1285 9

Guanylin-like peptides regulate electrolyte/water transport through the epithelia. Moreover, these peptides possess antiproliferative activity and regulate the turnover of epithelial cells. In an earlier study we localized guanylin immunoreactivity in secretory ducts of adult rodent salivary glands. In this study we investigated the appearance and distribution pattern of this peptide during the development of rat salivary glands. Guanylin immunoreactivity appeared at the beginning of cell differentiation from solid bud, on embryonic day 17 in the submandibular and sublingual glands and after day 18 in the parotid gland. Guanylin immunoreactivity appeared first in ductal and acinar anlage: its cell distribution pattern and fate differed in these two compartments. In the duct cells guanylin immunoreactivity spread after the duct system developed, whereas in acinar cells it disappeared after cell differentiation. The guanylin immunoreactivity we detected in adult salivary duct cells accords with guanylin's role in regulating electrolyte and water transport through the various epithelia. It does so by activating guanylate cyclase-C receptor, increasing intracellular cGMP concentration, and phosphorylating the cystic fibrosis transmembrane conductance regulator (CFTR) protein by the cGMP-dependent protein kinase II. This signaling cascade couples to the ductal electrolyte/water secretion and modulates finally the electrolyte composition of the saliva. On the other hand, CFTR is also involved in mechanisms of cell growth, by regulating apoptosis, and promoting cell differentiation. The early diffuse guanylin immunoreactivity we observed in ducts and acinar anlage, before the secretory set is operative, suggests guanylin has a role in cell differentiation.
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PMID:Ontogeny of guanylin-immunoreactive cells in rat salivary glands. 1498 29

Phosphorylation of Ser19 on the 20-kDa regulatory light chain of myosin II (MLC20) by Ca2+/calmodulin-dependent myosin light-chain kinase (MLCK) is essential for initiation of smooth muscle contraction. The initial [Ca2+]i transient is rapidly dissipated and MLCK inactivated, whereas MLC20 and muscle contraction are well maintained. Sustained contraction does not reflect Ca2+ sensitization because complete inhibition of MLC phosphatase activity in the absence of Ca2+ induces smooth muscle contraction. This contraction is suppressed by staurosporine, implying participation of a Ca2+-independent MLCK. Thus, sustained contraction, as with agonist-induced contraction at experimentally fixed Ca2+ concentrations, involves (a) G protein activation, (b) regulated inhibition of MLC phosphatase, and (c) MLC20 phosphorylation via a Ca2+-independent MLCK. The pathways that lead to inhibition of MLC phosphatase by G(q/13)-coupled receptors are initiated by sequential activation of Galpha(q)/alpha13, RhoGEF, and RhoA, and involve Rho kinase-mediated phosphorylation of the regulatory subunit of MLC phosphatase (MYPT1) and/or PKC-mediated phosphorylation of CPI-17, an endogenous inhibitor of MLC phosphatase. Sustained MLC20 phosphorylation is probably induced by the Ca2+-independent MLCK, ZIP kinase. The pathways initiated by G(i)-coupled receptors involve sequential activation of Gbetagamma(i), PI 3-kinase, and the Ca2+-independent MLCK, integrin-linked kinase. The last phosphorylates MLC20 directly and inhibits MLC phosphatase by phosphorylating CPI-17. PKA and PKG, which mediate relaxation, act upstream to desensitize the receptors (VPAC2 and NPR-C), inhibit adenylyl and guanylyl cyclase activities, and stimulate cAMP-specific PDE3 and PDE4 and cGMP-specific PDE5 activities. These kinases also act downstream to inhibit (a) initial contraction by inhibiting Ca2+ mobilization and (b) sustained contraction by inhibiting RhoA and targets downstream of RhoA. This increases MLC phosphatase activity and induces MLC20 dephosphorylation and muscle relaxation.
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PMID:Signaling for contraction and relaxation in smooth muscle of the gut. 1646 Feb 76

Ischemic preconditioning renders the heart resistant to infarction from ischemia/reperfusion. Over the past two decades a great deal has been learned about preconditioning's mechanism. Adenosine, bradykinin, and opioids act in parallel to trigger the preconditioned state and do so by activating PKC. While adenosine couples directly to PKC through the phospholipases, bradykinin and opioids do so through a complex pathway that includes in order: phosphatidylinositol 3-kinase (PI3-kinase), Akt, nitric oxide synthase, guanylyl cyclase, PKG, opening of mitochondrial K(ATP) channels, and activation of PKC by redox signaling. There are even differences between the opioid and bradykinin coupling as the former activates PI3-kinase through transactivation of the epidermal growth factor receptor while the latter has an unknown coupling mechanism. Protection stems from inhibition of formation of mitochondrial permeability transition pores early in reperfusion through activation of the survival kinases, Akt and ERK. These kinases are activated as a result of PKC somehow promoting signaling from adenosine A(2) receptors early in reperfusion. The survival kinases are thought to inhibit pore formation by phosphorylating GSK-3beta. The reperfused heart requires the support of the protective signals for only about an hour after which the ischemic injury is repaired and the signals are no longer needed.
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PMID:Signaling pathways in ischemic preconditioning. 1751 69

Cardiac atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) modulate blood pressure and volume by activation of the receptor guanylyl cyclase-A (GC-A) and subsequent intracellular cGMP formation. Here we report what we believe to be a novel function of these peptides as paracrine regulators of vascular regeneration. In mice with systemic deletion of the GC-A gene, vascular regeneration in response to critical hind limb ischemia was severely impaired. Similar attenuation of ischemic angiogenesis was observed in mice with conditional, endothelial cell-restricted GC-A deletion (here termed EC GC-A KO mice). In contrast, smooth muscle cell-restricted GC-A ablation did not affect ischemic neovascularization. Immunohistochemistry and RT-PCR revealed BNP expression in activated satellite cells within the ischemic muscle, suggesting that local BNP elicits protective endothelial effects. Since within the heart, BNP is mainly induced in cardiomyocytes by mechanical load, we investigated whether the natriuretic peptide/GC-A system also regulates angiogenesis accompanying load-induced cardiac hypertrophy. EC GC-A KO hearts showed diminished angiogenesis, mild fibrosis, and diastolic dysfunction. In vitro BNP/GC-A stimulated proliferation and migration of cultured microvascular endothelia by activating cGMP-dependent protein kinase I and phosphorylating vasodilator-stimulated phosphoprotein and p38 MAPK. We therefore conclude that BNP, produced by activated satellite cells within ischemic skeletal muscle or by cardiomyocytes in response to pressure load, regulates the regeneration of neighboring endothelia via GC-A. This paracrine communication might be critically involved in coordinating muscle regeneration/hypertrophy and angiogenesis.
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PMID:The natriuretic peptide/guanylyl cyclase--a system functions as a stress-responsive regulator of angiogenesis in mice. 1948 12


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